WorldWideScience

Sample records for strike slip separation

  1. Oblique strike-slip motion off the Southeastern Continental Margin of India: Implication for the separation of Sri Lanka from India

    Science.gov (United States)

    Desa, Maria Ana; Ismaiel, Mohammad; Suresh, Yenne; Krishna, Kolluru Sree

    2018-05-01

    The ocean floor in the Bay of Bengal has evolved after the breakup of India from Antarctica since the Early Cretaceous. Recent geophysical investigations including updated satellite derived gravity map postulated two phases for the tectonic evolution of the Bay of Bengal, the first phase of spreading occurred in the NW-SE direction forming its Western Basin, while the second phase occurred in the N-S direction resulting in its Eastern Basin. Lack of magnetic data along the spreading direction in the Western Basin prompted us to acquire new magnetic data along four tracks (totaling ∼3000 km) to validate the previously identified magnetic anomaly picks. Comparison of the synthetic seafloor spreading model with the observed magnetic anomalies confirmed the presence of Mesozoic anomalies M12n to M0 in the Western Basin. Further, the model suggests that this spreading between India and Antarctica took place with half-spreading rates of 2.7-4.5 cm/yr. The trend of the fracture zones in the Western Basin with respect to that of the Southeastern Continental Margin of India (SCMI) suggests that SCMI is an oblique transform margin with 37° obliquity. Further, the SCMI consists of two oblique transform segments separated by a small rift segment. The strike-slip motion along the SCMI is bounded by the rift segments of the Northeastern Continental Margin of India and the southern margin of Sri Lanka. The margin configuration and fracture zones inferred in its conjugate Western Enderby Basin, East Antarctica helped in inferring three spreading corridors off the SCMI in the Western Basin of the Bay of Bengal. Detailed grid reconstruction models traced the oblique strike-slip motion off the SCMI since M12n time. The strike-slip motion along the short northern transform segment ended by M11n time. The longer transform segment, found east of Sri Lanka lost its obliquity and became a pure oceanic transform fault by M0 time. The eastward propagation of the Africa

  2. Origin and structure of major orogen-scale exhumed strike-slip

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    Cao, Shuyun; Neubauer, Franz

    2016-04-01

    The formation of major exhumed strike-slip faults represents one of the most important dynamic processes affecting the evolution of the Earth's lithosphere and surface. Detailed models of the potential initiation and properties and architecture of orogen-scale exhumed strike-slip faults and how these relate to exhumation are rare. In this study, we deal with key properties controlling the development of major exhumed strike-slip fault systems, which are equivalent to the deep crustal sections of active across fault zones. We also propose two dominant processes for the initiation of orogen-scale exhumed strike-slip faults: (1) pluton-controlled and (2) metamorphic core complex-controlled strike-slip faults. In these tectonic settings, the initiation of faults occurs by rheological weakening along hot-to-cool contacts and guides the overall displacement and ultimate exhumation. These processes result in a specific thermal and structural architecture of such faults. These types of strike-slip dominated fault zones are often subparallel to mountain ranges and expose a wide variety of mylonitic, cataclastic and non-cohesive fault rocks, which were formed at different structural levels of the crust during various stages of faulting. The high variety of distinctive fault rocks is a potential evidence for recognition of these types of strike-slip faults. Exhumation of mylonitic rocks is, therefore, a common feature of such reverse oblique-slip strike-slip faults, implying major transtensive and/or transpressive processes accompanying pure strike-slip motion during exhumation. Some orogen-scale strike-slip faults nucleate and initiate along rheologically weak zones, e.g. at granite intrusions, zones of low-strength minerals, thermally weakened crust due to ascending fluids, and lateral borders of hot metamorphic core complexes. A further mechanism is the juxtaposition of mechanically strong mantle lithosphere to hot asthenosphere in continental transform faults (e.g., San

  3. Strike-slip faults offshore southern Taiwan: implications for the oblique arc-continent collision processes

    Science.gov (United States)

    Fuh, Shi-Chie; Liu, Char-Shine; Lundberg, Neil; Reed, Donald L.

    1997-06-01

    Taiwan is the site of present-day oblique arc-continent collision between the Luzon arc of the Philippine Sea plate and the Chinese continental margin. The major structural pattern revealed from marine geophysical studies in the area offshore southern Taiwan is that of a doubly-vergent orogenic belt, bounded by significant zones of thrusting on the west and east of the submarine accretionary wedge. Due to the oblique collision process, strike-slip faults could play an important role in this convergent domain. Topographic lineaments revealed from new digital bathymetry data and seismic reflection profiles confirm the existence of three sets of strike-slip faults in the collision-subduction zone offshore southern Taiwan: the N-S-trending left-lateral strike-slip faults within the Luzon volcanic arc, the NE-SW-trending right-lateral strike-slip faults across the accretionary wedge, and the NNE-SSW-trending left-lateral strike-slip faults lie in the frontal portion of the accretionary wedge. These strike-slip faults overprint pre-existing folds and thrusts and may convert into oblique thrusts or thrusts as the forearc blocks accrete to the mountain belt. A bookshelf rotation model is used to explain the observed geometrical relationships of these strike-slip fault systems. Based on this model, the counter-clockwise rotation of the forearc blocks in the area offshore southern Taiwan could have caused extrusion of the accretionary wedge material into the forearc basin. The originally continuous forearc basin is thus deformed into several closed and separate proto-collisional basins such as the Southern Longitudinal Trough and Taitung Trough. A tectonic evolution model which emphasizes on the development of various structures at different stages of the oblique arc-continent collision for the Taiwan mountain belt is proposed.

  4. What causes an icy fault to slip? Investigating strike-slip failure conditions on Ganymede at Dardanus and Tiamat Sulcus.

    Science.gov (United States)

    Cameron, M. E.; Smith-Konter, B. R.; Burkhard, L. M.; Collins, G. C.; Seifert, F.; Pappalardo, R. T.

    2015-12-01

    Ganymede exhibits two geologically distinct terrains known as dark and light (grooved) terrain. The mechanism for a transition from dark to light terrain remains unclear; however, inferences of strike-slip faulting and distributed shear zones suggest that strike-slip tectonism may be important to the structural development of Ganymede's surface and in this transition. Here we investigate the role of tidal stresses on Ganymede in the formation and evolution of strike-slip structures in both dark and grooved terrains. Using numerical code SatStress, we calculate both diurnal and non-synchronous rotation (NSR) tidal stresses at Ganymede's surface. Specifically, we investigate the role of fault friction and orbital eccentricity in the development of ~45 km of right-lateral offset at Dardanus Sulcus and a possible case of study with a detailed morphological mapping of strike-slip morphologies (en echelon structures, strike-slip duplexes, laterally offset pre-existing features, and possible strained craters) at Nun Sulcus and several other locations. These structures serve as example regions to provide improved constraints for global stress mechanisms responsible for strike-slip fault evolution on Ganymede.

  5. Active strike-slip faulting in El Salvador, Central America

    Science.gov (United States)

    Corti, Giacomo; Carminati, Eugenio; Mazzarini, Francesco; Oziel Garcia, Marvyn

    2005-12-01

    Several major earthquakes have affected El Salvador, Central America, during the Past 100 yr as a consequence of oblique subduction of the Cocos plate under the Caribbean plate, which is partitioned between trench-orthogonal compression and strike-slip deformation parallel to the volcanic arc. Focal mechanisms and the distribution of the most destructive earthquakes, together with geomorphologic evidence, suggest that this transcurrent component of motion may be accommodated by a major strike-slip fault (El Salvador fault zone). We present field geological, structural, and geomorphological data collected in central El Salvador that allow the constraint of the kinematics and the Quaternary activity of this major seismogenic strike-slip fault system. Data suggest that the El Salvador fault zone consists of at least two main ˜E-W fault segments (San Vicente and Berlin segments), with associated secondary synthetic (WNW-ESE) and antithetic (NNW-SSE) Riedel shears and NW-SE tensional structures. The two main fault segments overlap in a dextral en echelon style with the formation of an intervening pull-apart basin. Our original geological and geomorphologic data suggest a late Pleistocene Holocene slip rate of ˜11 mm/yr along the Berlin segment, in contrast with low historical seismicity. The kinematics and rates of deformation suggested by our new data are consistent with models involving slip partitioning during oblique subduction, and support the notion that a trench-parallel component of motion between the Caribbean and Cocos plates is concentrated along E-W dextral strike-slip faults parallel to the volcanic arc.

  6. Shell Tectonics: A Mechanical Model for Strike-slip Displacement on Europa

    Science.gov (United States)

    Rhoden, Alyssa Rose; Wurman, Gilead; Huff, Eric M.; Manga, Michael; Hurford, Terry A.

    2012-01-01

    We introduce a new mechanical model for producing tidally-driven strike-slip displacement along preexisting faults on Europa, which we call shell tectonics. This model differs from previous models of strike-slip on icy satellites by incorporating a Coulomb failure criterion, approximating a viscoelastic rheology, determining the slip direction based on the gradient of the tidal shear stress rather than its sign, and quantitatively determining the net offset over many orbits. This model allows us to predict the direction of net displacement along faults and determine relative accumulation rate of displacement. To test the shell tectonics model, we generate global predictions of slip direction and compare them with the observed global pattern of strike-slip displacement on Europa in which left-lateral faults dominate far north of the equator, right-lateral faults dominate in the far south, and near-equatorial regions display a mixture of both types of faults. The shell tectonics model reproduces this global pattern. Incorporating a small obliquity into calculations of tidal stresses, which are used as inputs to the shell tectonics model, can also explain regional differences in strike-slip fault populations. We also discuss implications for fault azimuths, fault depth, and Europa's tectonic history.

  7. Strike-slip tectonics during rift linkage

    Science.gov (United States)

    Pagli, C.; Yun, S. H.; Ebinger, C.; Keir, D.; Wang, H.

    2017-12-01

    The kinematics of triple junction linkage and the initiation of transforms in magmatic rifts remain debated. Strain patterns from the Afar triple junction provide tests of current models of how rifts grow to link in area of incipient oceanic spreading. Here we present a combined analysis of seismicity, InSAR and GPS derived strain rate maps to reveal that the plate boundary deformation in Afar is accommodated primarily by extensional tectonics in the Red Sea and Gulf of Aden rifts, and does not require large rotations about vertical axes (bookshelf faulting). Additionally, models of stress changes and seismicity induced by recent dykes in one sector of the Afar triple junction provide poor fit to the observed strike-slip earthquakes. Instead we explain these patterns as rift-perpendicular shearing at the tips of spreading rifts where extensional strains terminate against less stretched lithosphere. Our results demonstrate that rift-perpendicular strike-slip faulting between rift segments achieves plate boundary linkage during incipient seafloor spreading.

  8. Magmatic control along a strike-slip volcanic arc: The central Aeolian arc (Italy)

    Science.gov (United States)

    Ruch, J.; Vezzoli, L.; De Rosa, R.; Di Lorenzo, R.; Acocella, V.

    2016-02-01

    The regional stress field in volcanic areas may be overprinted by that produced by magmatic activity, promoting volcanism and faulting. In particular, in strike-slip settings, the definition of the relationships between the regional stress field and magmatic activity remains elusive. To better understand these relationships, we collected stratigraphic, volcanic, and structural field data along the strike-slip central Aeolian arc (Italy): here the islands of Lipari and Vulcano separate the extensional portion of the arc (to the east) from the contractional one (to the west). We collected >500 measurements of faults, extension fractures, and dikes at 40 sites. Most structures are NNE-SSW to NNW-SSE oriented, eastward dipping, and show almost pure dip-slip motion, consistent with an E-W extension direction, with minor dextral and sinistral shear. Our data highlight six eruptive periods during the last 55 ka, which allow considering both islands as a single magmatic system, in which tectonic and magmatic activities steadily migrated eastward and currently focus on a 10 km long × 2 km wide active segment. Faulting appears to mostly occur in temporal and spatial relation with magmatic events, supporting that most of the observable deformation derives from transient magmatic activity (shorter term, days to months), rather than from steady longer-term regional tectonics (102-104 years). More in general, the central Aeolian case shows how magmatic activity may affect the structure and evolution of volcanic arcs, overprinting any strike-slip motion with magma-induced extension at the surface.

  9. Magmatic control along a strike-slip volcanic arc: The central Aeolian arc (Italy)

    KAUST Repository

    Ruch, Joel

    2016-01-23

    The regional stress field in volcanic areas may be overprinted by that produced by magmatic activity, promoting volcanism and faulting. In particular, in strike-slip settings, the definition of the relationships between the regional stress field and magmatic activity remains elusive. To better understand these relationships, we collected stratigraphic, volcanic and structural field data along the strike-slip Central Aeolian arc (Italy): here the islands of Lipari and Vulcano separate the extensional portion of the arc (to the east) from the contractional one (to the west). We collected >500 measurements of faults, extension fractures and dikes at 40 sites. Most structures are NNE-SSW to NNW-SSE oriented, eastward dipping, and show almost pure dip-slip motion; consistent with an E-W extension direction, with minor dextral and sinistral shear. Our data highlight six eruptive periods during the last 55 ka, which allow considering both islands as a single magmatic system, in which tectonic and magmatic activity steadily migrated eastward and currently focus on a 10 km long x 2 km wide active segment. Faulting appears to mostly occur in temporal and spatial relation with magmatic events, supporting that most of the observable deformation derives from transient magmatic activity (shorter-term, days to months), rather than from steady longer-term regional tectonics (102-104 years). More in general, the Central Aeolian case shows how magmatic activity may affect the structure and evolution of volcanic arcs, overprinting any strike-slip motion with magma-induced extension at the surface.

  10. Crimea-Kopet Dagh zone of concentrated orogenic deformations as a transregional late collisional right-lateral strike-slip fault

    Science.gov (United States)

    Patina, I. S.; Leonov, Yu. G.; Volozh, Yu. A.; Kopp, M. L.; Antipov, M. P.

    2017-07-01

    It is shown that the Crimea, Caucasus, and Kopet Dagh fold systems make up a single whole unified by a lithospheric strike-slip fault zone of concentrated dislocations. The strike-slip fault that dissects the sedimentary cover and consolidated crust is rooted in subcrustal layers of the mantle. The notions about strike-slip dislocations in the structure of the Crimea-Kopet Dagh System are considered. Comparative analysis of structure, age, and amplitude of strike-slip fault segments is carried out. The effect of strike-slip faulting on the deep-seated and near-surface structure of the Earth's crust is considered. Based on estimation of strike-slip offsets, the paleogeography of Paleogene basins is refined; their initial contours, which have been disturbed and fragmented by slipping motion strike-slip displacement, have been reconstructed.

  11. A Study of Interactions Between Thrust and Strike-slip Faults

    Directory of Open Access Journals (Sweden)

    Jeng-Cheng Wang

    2013-01-01

    Full Text Available A 3-D finite difference method is applied in this study to investigate a spontaneous rupture within a fault system which includes a primary thrust fault and two strike-slip sub-faults. With the occurrence of a rupture on a fault, the rupture condition follows Coulomb¡¦s friction law wherein the stress-slip obeys the slip-weakening fracture criteria. To overcome the geometrical complexity of such a system, a finite difference method is encoded in two different coordinate systems; then, the calculated displacements are connected between the two systems using a 2-D interpolation technique. The rupture is initiated at the center of the main fault under the compression of regional tectonic stresses and then propagates to the boundaries whereby the main fault rupture triggers two strike-slip sub-faults. Simulation results suggest that the triggering of two sub-faults is attributed to two primary factors, regional tectonic stresses and the relative distances between the two sub-faults and the main fault.

  12. The Role of Near-Fault Relief in Creating and Maintaining Strike-Slip Landscape Features

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    Harbert, S.; Duvall, A. R.; Tucker, G. E.

    2016-12-01

    Geomorphic landforms, such as shutter ridges, offset river terraces, and deflected stream channels, are often used to assess the activity and slip rates of strike-slip faults. However, in some systems, such as parts of the Marlborough Fault System (South Island, NZ), an active strike-slip fault does not leave a strong landscape signature. Here we explore the factors that dampen or enhance the landscape signature of strike-slip faulting using the Channel-Hillslope Integrated Landscape Development model (CHILD). We focus on variables affecting the length of channel offsets, which enhance the signature of strike-slip motion, and the frequency of stream captures, which eliminate offsets and reduce this signature. We model a strike-slip fault that passes through a mountain ridge, offsetting streams that drain across this fault. We use this setup to test the response of channel offset length and capture frequency to fault characteristics, such as slip rate and ratio of lateral to vertical motion, and to landscape characteristics, such as relief contrasts controlled by erodibility. Our experiments show that relief downhill of the fault, whether generated by differential uplift across the fault or by an erodibility contrast, has the strongest effect on offset length and capture frequency. This relief creates shutter ridges, which block and divert streams while being advected along a fault. Shutter ridges and the streams they divert have long been recognized as markers of strike-slip motion. Our results show specifically that the height of shutter ridges is most responsible for the degree to which they create long channel offsets by preventing stream captures. We compare these results to landscape metrics in the Marlborough Fault System, where shutter ridges are common and often lithologically controlled. We compare shutter ridge length and height to channel offset length in order to assess the influence of relief on offset channel features in a real landscape. Based on our

  13. The significance of strike-slip faulting in the basement of the Zagros fold and thrust belt

    Energy Technology Data Exchange (ETDEWEB)

    Hessami, K.; Koyi, H.A.; Talbot, C.J. [Uppsala University (Sweden). Institute of Earth Sciences

    2000-01-01

    Lateral offsets in the pattern of seismicity along the Zagros fold and thrust belt indicate that transverse faults segmenting the Arabian basement are active deep-seated strike-slip faults. The dominant NW-SE trending features of the belt have undergone repeated horizontal displacements along these transverse faults. These reactivated basement faults, which are inherited from the Pan-African construction phase, controlled both deposition of the Phanerozoic cover before Tertiary-Recent deformation of the Zagros and probably the entrapment of hydrocarbons on the NE margin of Arabia and in the Zagros area. We have used observations of faulting recognized on Landsat satellite images, in conjunction with the spatial distribution of earthquakes and their focal mechanism solutions, to infer a tectonic model for the Zagros basement. Deformation in the NW Zagros appears to be concentrated on basement thrusts and a few widely-spaced north-south trending strike-slip faults which separate major structural segments. In the SE Zagros, two main structural domains can be distinguished. A domain of NNW-trending right-lateral faults in the northern part of the SE Zagros implies that fault-bounded blocks are likely to have rotated anticlockwise about vertical axes relative to both Arabia and Central Iran. In contrast, the predominance of NNE-trending left-lateral faults in the southern part of the SE Zagros implies that fault-bounded blocks may have rotated clockwise about vertical axes. We propose a tectonic model in which crustal blocks bounded by strike-slip faults in a zone of simple shear rotate about vertical axes relative to both Arabia and Central Iran. The presence of domains of strike-slip and thrust faulting in the Zagros basement suggest that some of the convergence between Arabia and Central Iran is accommodated by rotation and possible lateral movement of crust along the belt by strike-slip faults, as well as by obvious crustal shortening and thickening along thrust

  14. Geologic Inheritance and Earthquake Rupture Processes: The 1905 M ≥ 8 Tsetserleg-Bulnay Strike-Slip Earthquake Sequence, Mongolia

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    Choi, Jin-Hyuck; Klinger, Yann; Ferry, Matthieu; Ritz, Jean-François; Kurtz, Robin; Rizza, Magali; Bollinger, Laurent; Davaasambuu, Battogtokh; Tsend-Ayush, Nyambayar; Demberel, Sodnomsambuu

    2018-02-01

    In 1905, 14 days apart, two M 8 continental strike-slip earthquakes, the Tsetserleg and Bulnay earthquakes, occurred on the Bulnay fault system, in Mongolia. Together, they ruptured four individual faults, with a total length of 676 km. Using submetric optical satellite images "Pleiades" with ground resolution of 0.5 m, complemented by field observation, we mapped in detail the entire surface rupture associated with this earthquake sequence. Surface rupture along the main Bulnay fault is 388 km in length, striking nearly E-W. The rupture is formed by a series of fault segments that are 29 km long on average, separated by geometric discontinuities. Although there is a difference of about 2 m in the average slip between the western and eastern parts of the Bulnay rupture, along-fault slip variations are overall limited, resulting in a smooth slip distribution, except for local slip deficit at segment boundaries. We show that damage, including short branches and secondary faulting, associated with the rupture propagation, occurred significantly more often along the western part of the Bulnay rupture, while the eastern part of the rupture appears more localized and thus possibly structurally simpler. Eventually, the difference of slip between the western and eastern parts of the rupture is attributed to this difference of rupture localization, associated at first order with a lateral change in the local geology. Damage associated to rupture branching appears to be located asymmetrically along the extensional side of the strike-slip rupture and shows a strong dependence on structural geologic inheritance.

  15. Onset of aseismic creep on major strike-slip faults

    KAUST Repository

    Çakir, Ziyadin

    2012-10-02

    Time series analysis of spaceborne synthetic aperture radar (SAR) data, GPS measurements, and fi eld observations reveal that the central section of the Izmit (Turkey) fault that slipped with a supershear rupture velocity in the A.D. 1999, Mw7.4, Izmit earthquake began creeping aseismically following the earthquake. Rapid initial postseismic afterslip decayed logarithmically with time and appears to have reached a steady rate comparable to the preearthquake full fault-crossing rate, suggesting that it may continue for decades and possibly until late in the earthquake cycle. If confi rmed by future monitoring, these observations identify postseismic afterslip as a mechanism for initiating creep behavior along strike-slip faults. Long-term afterslip and/or creep has signifi cant implications for earthquake cycle models, recurrence intervals of large earthquakes, and accordingly, seismic hazard estimation along mature strike-slip faults, in particular for Istanbul which is believed to lie adjacent to a seismic gap along the North Anatolian fault in the Sea of Marmara. © 2012 Geological Society of America.

  16. Onset of aseismic creep on major strike-slip faults

    KAUST Repository

    Ç akir, Ziyadin; Ergintav, Semih; Ö zener, Haluk; Doǧan, Uǧur; Akoglu, Ahmet; Meghraoui, Mustapha; Reilinger, Robert E.

    2012-01-01

    Time series analysis of spaceborne synthetic aperture radar (SAR) data, GPS measurements, and fi eld observations reveal that the central section of the Izmit (Turkey) fault that slipped with a supershear rupture velocity in the A.D. 1999, Mw7.4, Izmit earthquake began creeping aseismically following the earthquake. Rapid initial postseismic afterslip decayed logarithmically with time and appears to have reached a steady rate comparable to the preearthquake full fault-crossing rate, suggesting that it may continue for decades and possibly until late in the earthquake cycle. If confi rmed by future monitoring, these observations identify postseismic afterslip as a mechanism for initiating creep behavior along strike-slip faults. Long-term afterslip and/or creep has signifi cant implications for earthquake cycle models, recurrence intervals of large earthquakes, and accordingly, seismic hazard estimation along mature strike-slip faults, in particular for Istanbul which is believed to lie adjacent to a seismic gap along the North Anatolian fault in the Sea of Marmara. © 2012 Geological Society of America.

  17. Rheological structure of the lithosphere in plate boundary strike-slip fault zones

    Science.gov (United States)

    Chatzaras, Vasileios; Tikoff, Basil; Kruckenberg, Seth C.; Newman, Julie; Titus, Sarah J.; Withers, Anthony C.; Drury, Martyn R.

    2016-04-01

    How well constrained is the rheological structure of the lithosphere in plate boundary strike-slip fault systems? Further, how do lithospheric layers, with rheologically distinct behaviors, interact within the strike-slip fault zones? To address these questions, we present rheological observations from the mantle sections of two lithospheric-scale, strike-slip fault zones. Xenoliths from ˜40 km depth (970-1100 ° C) beneath the San Andreas fault system (SAF) provide critical constraints on the mechanical stratification of the lithosphere in this continental transform fault. Samples from the Bogota Peninsula shear zone (BPSZ, New Caledonia), which is an exhumed oceanic transform fault, provide insights on lateral variations in mantle strength and viscosity across the fault zone at a depth corresponding to deformation temperatures of ˜900 ° C. Olivine recrystallized grain size piezometry suggests that the shear stress in the SAF upper mantle is 5-9 MPa and in the BPSZ is 4-10 MPa. Thus, the mantle strength in both fault zones is comparable to the crustal strength (˜10 MPa) of seismogenic strike-slip faults in the SAF system. Across the BPSZ, shear stress increases from 4 MPa in the surrounding rocks to 10 MPa in the mylonites, which comprise the core of the shear zone. Further, the BPSZ is characterized by at least one order of magnitude difference in the viscosity between the mylonites (1018 Paṡs) and the surrounding rocks (1019 Paṡs). Mantle viscosity in both the BPSZ mylonites and the SAF (7.0ṡ1018-3.1ṡ1020 Paṡs) is relatively low. To explain our observations from these two strike-slip fault zones, we propose the "lithospheric feedback" model in which the upper crust and lithospheric mantle act together as an integrated system. Mantle flow controls displacement and the upper crust controls the stress magnitude in the system. Our stress data combined with data that are now available for the middle and lower crustal sections of other transcurrent fault

  18. Assemblage of strike-slip faults and tectonic extension and ...

    Indian Academy of Sciences (India)

    12

    the formation, evolution and distribution of these strike-slip faults have important. 80 ...... function of coal-derived gas study for natural gas industry development in China; .... Bohai-Zhangjiakou seismotectonic zone based on 3D visco-elastic ...

  19. High tsunami frequency as a result of combined strike-slip faulting and coastal landslides

    Science.gov (United States)

    Hornbach, Matthew J.; Braudy, Nicole; Briggs, Richard W.; Cormier, Marie-Helene; Davis, Marcy B.; Diebold, John B.; Dieudonne, Nicole; Douilly, Roby; Frohlich, Cliff; Gulick, Sean P.S.; Johnson, Harold E.; Mann, Paul; McHugh, Cecilia; Ryan-Mishkin, Katherine; Prentice, Carol S.; Seeber, Leonardo; Sorlien, Christopher C.; Steckler, Michael S.; Symithe, Steeve Julien; Taylor, Frederick W.; Templeton, John

    2010-01-01

    Earthquakes on strike-slip faults can produce devastating natural hazards. However, because they consist predominantly of lateral motion, these faults are rarely associated with significant uplift or tsunami generation. And although submarine slides can generate tsunami, only a few per cent of all tsunami are believed to be triggered in this way. The 12 January Mw 7.0 Haiti earthquake exhibited primarily strike-slip motion but nevertheless generated a tsunami. Here we present data from a comprehensive field survey that covered the onshore and offshore area around the epicentre to document that modest uplift together with slope failure caused tsunamigenesis. Submarine landslides caused the most severe tsunami locally. Our analysis suggests that slide-generated tsunami occur an order-of-magnitude more frequently along the Gonave microplate than global estimates predict. Uplift was generated because of the earthquake's location, where the Caribbean and Gonave microplates collide obliquely. The earthquake also caused liquefaction at several river deltas that prograde rapidly and are prone to failure. We conclude that coastal strike-slip fault systems such as the Enriquillo-Plantain Garden fault produce relief conducive to rapid sedimentation, erosion and slope failure, so that even modest predominantly strike-slip earthquakes can cause potentially catastrophic slide-generated tsunami - a risk that is underestimated at present.

  20. THE ILICA BRANCH OF THE SOUTHEASTERN ESKIŞEHIR FAULT ZONE: AN ACTIVE RIGHT LATERAL STRIKE-SLIP STRUCTURE IN CENTRAL ANATOLIA, TURKEY

    Directory of Open Access Journals (Sweden)

    Korhan ESAT

    2016-12-01

    Full Text Available The Eskişehir Fault Zone is one of the prominent neotectonic structures of Turkey. It separates the west  Anatolian extensional province and the strike-slip induced northwest central Anatolian contractional area in the Anatolian Block. Its southeastern part is generally divided into three branches, namely the Ilıca, Yeniceoba, and Cihanbeyli from north to south, respectively. The right lateral strike-slip Ilıca branch (IB is an approximately 100-km-long fault and it is composed of several segments in a northwest-southeast direction. The slickensides, subsidiary fractures, cataclastic zone, fracture-controlled drainage pattern, right lateral stream deflections, deformation in the Quaternary unit observing in the seismic reflection sections, and seismicity of the region all indicate that the IB is an active right lateral strike-slip fault. The IB has also a regional tectonic importance as a boundary fault between the contractional and the extensional regions in central Anatolia considering that it is the southern limit of the contraction-related structures in the west-southwest of Ankara.

  1. Strike-slip linked core complexes: A new kinematic model of basement rock exhumation in a crustal-scale fault system

    Science.gov (United States)

    Meyer, Sven Erik; Passchier, Cees; Abu-Alam, Tamer; Stüwe, Kurt

    2014-05-01

    Metamorphic core complexes usually develop as extensional features during continental crustal thinning, such as the Basin and Range and the Aegean Terrane. The Najd fault system in Saudi Arabia is a 2000 km-long and 400 km-wide complex network of crustal-scale strike-slip shear zones in a Neoproterozoic collision zone. Locally, the anastomosing shear zones lead to exhumation of lower crustal segments and represent a new kinematic model for the development of core complexes. We report on two such structures: the Qazaz complex in Saudi Arabia and the Hafafit complex in Egypt. The 15 km-wide Qazaz complex is a triangular dome of gently dipping mylonitic foliations within the 140 km-long sinistral strike-slip Qazaz mylonite zone. The gneissic dome consists of high-grade rocks, surrounded by low-grade metasediments and metavolcanics. The main SE-trending strike-slip Qazaz shear zone splits southwards into two branches around the gneiss dome: the western branch is continuous with the shallow dipping mylonites of the dome core, without overprinting, and changes by more than 90 degrees from a NS-trending strike-slip zone to an EW-trending 40 degree south-dipping detachment that bounds the gneiss dome to the south. The eastern SE-trending sinistral strike-slip shear zone branch is slightly younger and transects the central dome fabrics. The gneiss dome appears to have formed along a jog in the strike-slip shear zone during 40 km of horizontal strike-slip motion, which caused local exhumation of lower crustal rocks by 25 km along the detachment. The eastern shear zone branch formed later during exhumation, transacted the gneiss dome and offset the two parts by another 70 km. The Hafafit core complex in Egypt is of similar shape and size to the Qazaz structure, but forms the northern termination of a sinistral strike-slip zone that is at least 100 km in length. This zone may continue into Saudi Arabia as the Ajjaj shear zone for another 100 km. The NW trending strike slip

  2. Transition from strike-slip faulting to oblique subduction: active tectonics at the Puysegur Margin, South New Zealand

    Science.gov (United States)

    Lamarche, Geoffroy; Lebrun, Jean-Frédéric

    2000-01-01

    South of New Zealand the Pacific-Australia (PAC-AUS) plate boundary runs along the intracontinental Alpine Fault, the Puysegur subduction front and the intraoceanic Puysegur Fault. The Puysegur Fault is located along Puysegur Ridge, which terminates at ca. 47°S against the continental Puysegur Bank in a complex zone of deformation called the Snares Zone. At Puysegur Trench, the Australian Plate subducts beneath Puysegur Bank and the Fiordland Massif. East of Fiordland and Puysegur Bank, the Moonlight Fault System (MFS) represents the Eocene strike-slip plate boundary. Interpretation of seafloor morphology and seismic reflection profiles acquired over Puysegur Bank and the Snares Zone allows study of the transition from intraoceanic strike-slip faulting along the Puysegur Ridge to oblique subduction at the Puysegur Trench and to better understand the genetic link between the Puysegur Fault and the MFS. Seafloor morphology is interpreted from a bathymetric dataset compiled from swath bathymetry data acquired during the 1993 Geodynz survey, and single beam echo soundings acquired by the NZ Royal Navy. The Snares Zone is the key transition zone from strike-slip faulting to subduction. It divides into three sectors, namely East, NW and SW sectors. A conspicuous 3600 m-deep trough (the Snares Trough) separates the NW and East sectors. The East sector is characterised by the NE termination of Puysegur Ridge into right-stepping en echelon ridges that accommodate a change of strike from the Puysegur Fault to the MFS. Between 48°S and 47°S, in the NW sector and the Snares Trough, a series of transpressional faults splay northwards from the Puysegur Fault. Between 49°50'S and 48°S, thrusts develop progressively at Puysegur Trench into a decollement. North of 48°S the Snares Trough develops between two splays of the Puysegur Fault, indicating superficial extension associated with the subsidence of Puysegur Ridge. Seismic reflection profiles and bathymetric maps show a

  3. Characterization of Aftershock Sequences from Large Strike-Slip Earthquakes Along Geometrically Complex Faults

    Science.gov (United States)

    Sexton, E.; Thomas, A.; Delbridge, B. G.

    2017-12-01

    Large earthquakes often exhibit complex slip distributions and occur along non-planar fault geometries, resulting in variable stress changes throughout the region of the fault hosting aftershocks. To better discern the role of geometric discontinuities on aftershock sequences, we compare areas of enhanced and reduced Coulomb failure stress and mean stress for systematic differences in the time dependence and productivity of these aftershock sequences. In strike-slip faults, releasing structures, including stepovers and bends, experience an increase in both Coulomb failure stress and mean stress during an earthquake, promoting fluid diffusion into the region and further failure. Conversely, Coulomb failure stress and mean stress decrease in restraining bends and stepovers in strike-slip faults, and fluids diffuse away from these areas, discouraging failure. We examine spatial differences in seismicity patterns along structurally complex strike-slip faults which have hosted large earthquakes, such as the 1992 Mw 7.3 Landers, the 2010 Mw 7.2 El-Mayor Cucapah, the 2014 Mw 6.0 South Napa, and the 2016 Mw 7.0 Kumamoto events. We characterize the behavior of these aftershock sequences with the Epidemic Type Aftershock-Sequence Model (ETAS). In this statistical model, the total occurrence rate of aftershocks induced by an earthquake is λ(t) = λ_0 + \\sum_{i:t_i

  4. Strike-slip deformation reflects complex partitioning of strain in the Nankai Accretionary Prism (SE Japan)

    Science.gov (United States)

    Azevedo, Marco C.; Alves, Tiago M.; Fonseca, Paulo E.; Moore, Gregory F.

    2018-01-01

    Previous studies have suggested predominant extensional tectonics acting, at present, on the Nankai Accretionary Prism (NAP), and following a parallel direction to the convergence vector between the Philippine Sea and Amur Plates. However, a complex set of thrusts, pop-up structures, thrust anticlines and strike-slip faults is observed on seismic data in the outer wedge of the NAP, hinting at a complex strain distribution across SE Japan. Three-dimensional (3D) seismic data reveal three main families of faults: (1) NE-trending thrusts and back-thrusts; (2) NNW- to N-trending left-lateral strike-slip faults; and (3) WNW-trending to E-W right-lateral strike-slip faults. Such a fault pattern suggests that lateral slip, together with thrusting, are the two major styles of deformation operating in the outer wedge of the NAP. Both styles of deformation reflect a transpressional tectonic regime in which the maximum horizontal stress is geometrically close to the convergence vector. This work is relevant because it shows a progressive change from faults trending perpendicularly to the convergence vector, to a broader partitioning of strain in the form of thrusts and conjugate strike-slip faults. We suggest that similar families of faults exist within the inner wedge of the NAP, below the Kumano Basin, and control stress accumulation and strain accommodation in this latter region.

  5. The cenozoic strike-slip faults and TTHE regional crust stability of Beishan area

    International Nuclear Information System (INIS)

    Guo Zhaojie; Zhang Zhicheng; Zhang Chen; Liu Chang; Zhang Yu; Wang Ju; Chen Weiming

    2008-01-01

    The remote sensing images and geological features of Beishan area indicate that the Altyn Tagh fault, Sanweishan-Shuangta fault, Daquan fault and Hongliuhe fault are distributed in Beishan area from south to north. The faults are all left-lateral strike-slip faults with trending of NE40-50°, displaying similar distribution pattern. The secondary branch faults are developed at the end of each main strike-slip fault with nearly east to west trending form dendritic oblique crossings at the angle of 30-50°. Because of the left-lateral slip of the branch faults, the granites or the blocks exposed within the branch faults rotate clockwisely, forming 'Domino' structures. So the structural style of Beishan area consists of the Altyn Tagh fault, Sanweishan-Shuangta fault, Daquan fault, Hongliuhe fault and their branch faults and rotational structures between different faults. Sedimentary analysis on the fault valleys in the study area and ESR chronological test of fault clay exhibit that the Sanweishan-Shuangta fault form in the late Pliocene (N2), while the Daquan fault displays formation age of l.5-1.2 Ma, and the activity age of the relevant branch faults is Late Pleistocene (400 ka). The ages become younger from the Altyn Tagh fault to the Daquan fault and strike-slip faults display NW trending extension, further revealing the lateral growth process of the strike-slip boundary at the northern margin during the Cenozoic uplift of Tibetan Plateau. The displacement amounts on several secondary faults caused by the activities of the faults are slight due to the above-mentioned structural distribution characteristics of Beishan area, which means that this area is the most stable active area with few seismic activities. We propose the main granitic bodies in Beishan area could be favorable preselected locations for China's high level radioactive waste repository. (authors)

  6. Non-Andersonian conjugate strike-slip faults: Observations, theory, and tectonic implications

    International Nuclear Information System (INIS)

    Yin, A; Taylor, M H

    2008-01-01

    Formation of conjugate strike-slip faults is commonly explained by the Anderson fault theory, which predicts a X-shaped conjugate fault pattern with an intersection angle of ∼30 degrees between the maximum compressive stress and the faults. However, major conjugate faults in Cenozoic collisional orogens, such as the eastern Alps, western Mongolia, eastern Turkey, northern Iran, northeastern Afghanistan, and central Tibet, contradict the theory in that the conjugate faults exhibit a V-shaped geometry with intersection angles of 60-75 degrees, which is 30-45 degrees greater than that predicted by the Anderson fault theory. In Tibet and Mongolia, geologic observations can rule out bookshelf faulting, distributed deformation, and temporal changes in stress state as explanations for the abnormal fault patterns. Instead, the GPS-determined velocity field across the conjugate fault zones indicate that the fault formation may have been related to Hagen-Poiseuille flow in map view involving the upper crust and possibly the whole lithosphere based on upper mantle seismicity in southern Tibet and basaltic volcanism in Mongolia. Such flow is associated with two coeval and parallel shear zones having opposite shear sense; each shear zone produce a set of Riedel shears, respectively, and together the Riedel shears exhibit the observed non-Andersonian conjugate strike-slip fault pattern. We speculate that the Hagen-Poiseuille flow across the lithosphere that hosts the conjugate strike-slip zones was produced by basal shear traction related to asthenospheric flow, which moves parallel and away from the indented segment of the collisional fronts. The inferred asthenospheric flow pattern below the conjugate strike-slip fault zones is consistent with the magnitude and orientations of seismic anisotropy observed across the Tibetan and Mongolian conjugate fault zones, suggesting a strong coupling between lithospheric deformation and asthenospheric flow. The laterally moving

  7. Non-Andersonian conjugate strike-slip faults: Observations, theory, and tectonic implications

    Energy Technology Data Exchange (ETDEWEB)

    Yin, A [Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90025-1567 (United States); Taylor, M H [Department of Geology, University of Kansas, 1475 Jayhawk Blvd., Lawrence, KS 66044 (United States)], E-mail: yin@ess.ucla.edu

    2008-07-01

    Formation of conjugate strike-slip faults is commonly explained by the Anderson fault theory, which predicts a X-shaped conjugate fault pattern with an intersection angle of {approx}30 degrees between the maximum compressive stress and the faults. However, major conjugate faults in Cenozoic collisional orogens, such as the eastern Alps, western Mongolia, eastern Turkey, northern Iran, northeastern Afghanistan, and central Tibet, contradict the theory in that the conjugate faults exhibit a V-shaped geometry with intersection angles of 60-75 degrees, which is 30-45 degrees greater than that predicted by the Anderson fault theory. In Tibet and Mongolia, geologic observations can rule out bookshelf faulting, distributed deformation, and temporal changes in stress state as explanations for the abnormal fault patterns. Instead, the GPS-determined velocity field across the conjugate fault zones indicate that the fault formation may have been related to Hagen-Poiseuille flow in map view involving the upper crust and possibly the whole lithosphere based on upper mantle seismicity in southern Tibet and basaltic volcanism in Mongolia. Such flow is associated with two coeval and parallel shear zones having opposite shear sense; each shear zone produce a set of Riedel shears, respectively, and together the Riedel shears exhibit the observed non-Andersonian conjugate strike-slip fault pattern. We speculate that the Hagen-Poiseuille flow across the lithosphere that hosts the conjugate strike-slip zones was produced by basal shear traction related to asthenospheric flow, which moves parallel and away from the indented segment of the collisional fronts. The inferred asthenospheric flow pattern below the conjugate strike-slip fault zones is consistent with the magnitude and orientations of seismic anisotropy observed across the Tibetan and Mongolian conjugate fault zones, suggesting a strong coupling between lithospheric deformation and asthenospheric flow. The laterally moving

  8. Structural setting and kinematics of Nubian fault system, SE Western Desert, Egypt: An example of multi-reactivated intraplate strike-slip faults

    Science.gov (United States)

    Sakran, Shawky; Said, Said Mohamed

    2018-02-01

    Detailed surface geological mapping and subsurface seismic interpretation have been integrated to unravel the structural style and kinematic history of the Nubian Fault System (NFS). The NFS consists of several E-W Principal Deformation Zones (PDZs) (e.g. Kalabsha fault). Each PDZ is defined by spectacular E-W, WNW and ENE dextral strike-slip faults, NNE sinistral strike-slip faults, NE to ENE folds, and NNW normal faults. Each fault zone has typical self-similar strike-slip architecture comprising multi-scale fault segments. Several multi-scale uplifts and basins were developed at the step-over zones between parallel strike-slip fault segments as a result of local extension or contraction. The NNE faults consist of right-stepping sinistral strike-slip fault segments (e.g. Sin El Kiddab fault). The NNE sinistral faults extend for long distances ranging from 30 to 100 kms and cut one or two E-W PDZs. Two nearly perpendicular strike-slip tectonic regimes are recognized in the NFS; an inactive E-W Late Cretaceous - Early Cenozoic dextral transpression and an active NNE sinistral shear.

  9. Strike-slip tectonics and Quaternary basin formation along the Vienna Basin fault system inferred from Bouguer gravity derivatives

    NARCIS (Netherlands)

    Salcher, B. C.; Meurers, B.; Smit, J.; Decker, K.; HöLzel, M.; Wagreich, M.

    2012-01-01

    The Vienna Basin at the transition between the Alpine and Carpathian belt hosts a number of large Pleistocene sub-basins forming along an active continental scale strike-slip fault (Vienna Basin strike-slip fault). We utilize first-order derivatives from industrial Bouguer gravity data to unravel

  10. Right-lateral shear and rotation as the explanation for strike-slip faulting in eastern Tibet

    Science.gov (United States)

    England, Philip; Molnar, Peter

    1990-01-01

    Bounds are placed here on the rate of rotation proposed by Cobbold and Davy (1988) for the major strike-slip faults in the eastern Tibetan Plateau. It is also concluded here that the image of lateral transport on such faults, known also as continental escape, extrusion, or expulsion, is an illusion, and that instead the left-lateral slip on east-striking plates in eastern Tibet is a manifestation of north-striking right-lateral simple shear. If this conclusion is correct, the east-striking left-lateral faults and the crustal blocks between them are rotating clockwise at 1-2 deg/Myr, the east-west dimension of eastern Tibet is shortening at 10-20 mm/yr, and little material is moving eastward out of India's path into Eursasia by left-lateral simple shear.

  11. Evolution of strike-slip fault systems and associated geomorphic structures. Model test

    International Nuclear Information System (INIS)

    Ueta, Keichi

    2003-01-01

    Sandbox experiments were performed to investigate evolution of fault systems and its associated geomorphic structures caused by strike-slip motion on basement faults. A 200 cm long, 40 cm wide, 25 cm high sandbox was used in a strike-slip fault model test. Computerized X-ray tomography applied to the sandbox experiments made it possible to analyze the kinematic evaluation, as well as the three-dimensional geometry, of the faults. The deformation of the sand pack surface was analyzed by use of a laser method 3D scanner, which is a three-dimensional noncontact surface profiling instrument. A comparison of the experimental results with natural cases of active faults reveals the following: In the left-lateral strike-slip fault experiments, the deformation of the sand pack with increasing basement displacement is observed as follows. 1) In three dimensions, the right-stepping shears that have a cirque'/'shell'/'shipbody' shape develop on both sides of the basement fault. The shears on one side of the basement fault join those on the other side, resulting in helicoidal shaped shear surfaces. Shears reach the surface of the sand near or above the basement fault and en echelon Riedel shears are observed at the surface of the sand. The region between two Riedels is always an up-squeezed block. 2) lower-angle shears generally branch off from the first Riedel shears. 3) Pressure ridges develop within the zone defined by the right-stepping helicoidal shaped lower-angle shears. 4) Grabens develop between the pressure ridges. 5) Y-shears offset the pressure ridges. 6) With displacement concentrated on the central throughgoing fault zone, a liner trough developed directly above the basement fault. R1 shear and P foliation are observed in the liner trough. Such evolution of the shears and its associated structures in the fault model tests agrees well with that of strike-slip fault systems and its associated geomorphic structures. (author)

  12. States of stress and slip partitioning in a continental scale strike-slip duplex: Tectonic and magmatic implications by means of finite element modeling

    Science.gov (United States)

    Iturrieta, Pablo Cristián; Hurtado, Daniel E.; Cembrano, José; Stanton-Yonge, Ashley

    2017-09-01

    Orogenic belts at oblique convergent subduction margins accommodate deformation in several trench-parallel domains, one of which is the magmatic arc, commonly regarded as taking up the margin-parallel, strike-slip component. However, the stress state and kinematics of volcanic arcs is more complex than usually recognized, involving first- and second-order faults with distinctive slip senses and mutual interaction. These are usually organized into regional scale strike-slip duplexes, associated with both long-term and short-term heterogeneous deformation and magmatic activity. This is the case of the 1100 km-long Liquiñe-Ofqui Fault System in the Southern Andes, made up of two overlapping margin-parallel master faults joined by several NE-striking second-order faults. We present a finite element model addressing the nature and spatial distribution of stress across and along the volcanic arc in the Southern Andes to understand slip partitioning and the connection between tectonics and magmatism, particularly during the interseismic phase of the subduction earthquake cycle. We correlate the dynamics of the strike-slip duplex with geological, seismic and magma transport evidence documented by previous work, showing consistency between the model and the inferred fault system behavior. Our results show that maximum principal stress orientations are heterogeneously distributed within the continental margin, ranging from 15° to 25° counter-clockwise (with respect to the convergence vector) in the master faults and 10-19° clockwise in the forearc and backarc domains. We calculate the stress tensor ellipticity, indicating simple shearing in the eastern master fault and transpressional stress in the western master fault. Subsidiary faults undergo transtensional-to-extensional stress states. The eastern master fault displays slip rates of 5 to 10 mm/yr, whereas the western and subsidiary faults show slips rates of 1 to 5 mm/yr. Our results endorse that favorably oriented

  13. Strike-slip pull-apart process and emplacement of Xiangshan uranium-producing volcanic basin

    International Nuclear Information System (INIS)

    Qiu Aijin; Guo Lingzhi; Shu Liangshu

    2001-01-01

    Xiangshan volcanic basin is one of the famous uranium-producing volcanic basins in China. Emplacement mechanism of Xiangshan uranium-producing volcanic basin is discussed on the basis of the latest research achievements of deep geology in Xiangshan area and the theory of continental dynamics. The study shows that volcanic activity in Xiangshan volcanic basin may be divided into two cycles, and its emplacement is controlled by strike-ship pull-apart process originated from the deep regional faults. Volcanic apparatus in the first cycle was emplaced in EW-trending structure activated by clockwise strike-slipping of NE-trending deep fault, forming the EW-trending fissure-type volcanic effusion belt. Volcanic apparatus in the second cycle was emplaced at junction points of SN-trending pull-apart structure activated by sinistral strike-slipping of NE-trending deep faults and EW-trending basement faults causing the center-type volcanic magma effusion and extrusion. Moreover, the formation mechanism of large-rich uranium deposits is discussed as well

  14. Effect of inherited structures on strike-slip plate boundaries: insight from analogue modelling of the central Levant Fracture System, Lebanon

    Science.gov (United States)

    Ghalayini, Ramadan; Daniel, Jean-Marc; Homberg, Catherine; Nader, Fadi

    2015-04-01

    Analogue sandbox modeling is a tool to simulate deformation style and structural evolution of sedimentary basins. The initial goal is to test what is the effect of inherited and crustal structures on the propagation, evolution, and final geometry of major strike-slip faults at the boundary between two tectonic plates. For this purpose, we have undertaken a series of analogue models to validate and reproduce the structures of the Levant Fracture System, a major NNE-SSW sinistral strike-slip fault forming the boundary between the Arabian and African plates. Onshore observations and recent high quality 3D seismic data in the Levant Basin offshore Lebanon demonstrated that Mesozoic ENE striking normal faults were reactivated into dextral strike-slip faults during the Late Miocene till present day activity of the plate boundary which shows a major restraining bend in Lebanon with a ~ 30°clockwise rotation in its trend. Experimental parameters consisted of a silicone layer at the base simulating the ductile crust, overlain by intercalated quartz sand and glass sand layers. Pre-existing structures were simulated by creating a graben in the silicone below the sand at an oblique (>60°) angle to the main throughgoing strike-slip fault. The latter contains a small stepover at depth to create transpression during sinistral strike-slip movement and consequently result in mountain building similarly to modern day Lebanon. Strike-slip movement and compression were regulated by steady-speed computer-controlled engines and the model was scanned using a CT-scanner continuously while deforming to have a final 4D model of the system. Results showed that existing normal faults were reactivated into dextral strike-slip faults as the sinistral movement between the two plates accumulated. Notably, the resulting restraining bend is asymmetric and segmented into two different compartments with differing geometries. One compartment shows a box fold anticline, while the second shows an

  15. Strike-Slip Fault Deformation and Its Control in Hydrocarbon Trapping in Ketaling Area, Jambi Subbasin, Indonesia

    Science.gov (United States)

    Ramadhan, Aldis; Badai Samudra, Alexis; Jaenudin; Puji Lestari, Enik; Saputro, Julian; Sugiono; Hirosiadi, Yosi; Amrullah, Indi

    2018-03-01

    Geologically, Ketaling area consists of a local high considered as flexure margin of Tempino-Kenali Asam Deep in west part and graben in east part also known as East Ketaling Deep. Numerous proven plays were established in Ketaling area with reservoir in early Miocene carbonate and middle Miocene sand. This area underwent several major deformations. Faults are developed widely, yet their geometrical features and mechanisms of formation remained so far indistinct, which limited exploration activities. With new three-dimensional seismic data acquired in 2014, this area evidently interpreted as having strike-slip mechanism. The objective of this study is to examine characteristic of strike slip fault and its affect to hydrocarbon trapping in Ketaling Area. Structural pattern and characteristic of strike slip fault deformation was examined with integration of normal seismic with variance seismic attribute analysis and the mapping of Syn-rift to Post-rift horizon. Seismic flattening on 2D seismic cross section with NW-SE direction is done to see the structural pattern related to horst (paleohigh) and graben. Typical flower structure, branching strike-slip fault system and normal fault in synrift sediment clearly showed in section. An echelon pattern identified from map view as the result of strike slip mechanism. Detail structural geology analysis show the normal fault development which has main border fault in the southern of Ketaling area dipping to the Southeast-East with NE-SW lineament. These faults related to rift system in Ketaling area. NW-SE folds with reactive NE-SW fault which act as hydrocarbon trapping in the shallow zone. This polyphase tectonic formed local graben, horst and inverted structure developed a good kitchen area (graben) and traps (horst, inverted structure). Subsequently, hydrocarbon accumulation potentials such as basement fractures, inverted syn-rift deposit and shallow zone are very interesting to explore in this area.

  16. Late Pleistocene-Holocene Activity of the Strike-slip Xianshuihe Fault Zone, Tibetan Plateau, Inferred from Tectonic Landforms

    Science.gov (United States)

    Lin, A.; Yan, B.

    2017-12-01

    Knowledges on the activity of the strike-slip fault zones on the Tibetan Plateau have been promoted greatly by the interpretation of remote sensing images (Molnar and Tapponnier, 1975; Tapponnier and Molnar, 1977). The active strike-slip Xianshuihe-Xiaojiang Fault System (XXFS), with the geometry of an arc projecting northeastwards, plays an important role in the crustal deformation of the Tibetan Plateau caused by the continental collision between the Indian and Eurasian plates. The Xianshuihe Fault Zone (XFZ) is located in the central segment of the XXFS and extends for 370 km, with a maximum sinistral offset of 60 km since 13‒5 Ma. In this study, we investigated the tectonic landforms and slip rate along the central segment of the left-lateral strike-slip XFZ. Field investigations and analysis of ttectonic landforms show that horizontal offset has been accumulated on the topographical markers of different scales that developed since the Last Glacial Maximum (LGM). The central segment of the XFZ is composed of three major faults: Yalahe, Selaha, and Zheduotang faults showing a right-stepping echelon pattern, that is characterized by systematical offset of drainages, alluvial fans and terrace risers with typical scissoring structures, indicating a structural feature of left-lateral strike-slip fault. Based on the offset glacial morphology and radiocarbon dating ages, we estimate the Late Pleistocene-Holocene slip rate to be 10 mm/yr for the central segment of the XFZ, which is consistent with that estimated from the GPS observations and geological evidence as reported previously. Across the central segment of the XFZ, the major Selaha and Zheduotang faults participate a slip rate of 5.8 mm/yr and 3.4 mm/yr, respectively. Detailed investigations of tectonic landforms are essential for the understanding the activity of active faults. Our findings suggest that the left-lateral slipping of the XFZ partitions the deformation of eastward extrusion and northeastward

  17. Geometry and kinematics of adhesive wear in brittle strike-slip fault zones

    Science.gov (United States)

    Swanson, Mark T.

    2005-05-01

    Detailed outcrop surface mapping in Late Paleozoic cataclastic strike-slip faults of coastal Maine shows that asymmetric sidewall ripouts, 0.1-200 m in length, are a significant component of many mapped faults and an important wall rock deformation mechanism during faulting. The geometry of these structures ranges from simple lenses to elongate slabs cut out of the sidewalls of strike-slip faults by a lateral jump of the active zone of slip during adhesion along a section of the main fault. The new irregular trace of the active fault after this jump creates an indenting asperity that is forced to plow through the adjoining wall rock during continued adhesion or be cut off by renewed motion along the main section of the fault. Ripout translation during adhesion sets up the structural asymmetry with trailing extensional and leading contractional ends to the ripout block. The inactive section of the main fault trace at the trailing end can develop a 'sag' or 'half-graben' type geometry due to block movement along the scallop-shaped connecting ramp to the flanking ripout fault. Leading contractional ramps can develop 'thrust' type imbrication and forces the 'humpback' geometry to the ripout slab due to distortion of the inactive main fault surface by ripout translation. Similar asymmetric ripout geometries are recognized in many other major crustal scale strike-slip fault zones worldwide. Ripout structures in the 5-500 km length range can be found on the Atacama fault system of northern Chile, the Qujiang and Xiaojiang fault zones in western China, the Yalakom-Hozameen fault zone in British Columbia and the San Andreas fault system in southern California. For active crustal-scale faults the surface expression of ripout translation includes a coupled system of extensional trailing ramps as normal oblique-slip faults with pull-apart basin sedimentation and contractional leading ramps as oblique thrust or high angle reverse faults with associated uplift and erosion. The

  18. Effects of Strike-Slip Fault Segmentation on Earthquake Energy and Seismic Hazard

    Science.gov (United States)

    Madden, E. H.; Cooke, M. L.; Savage, H. M.; McBeck, J.

    2014-12-01

    Many major strike-slip faults are segmented along strike, including those along plate boundaries in California and Turkey. Failure of distinct fault segments at depth may be the source of multiple pulses of seismic radiation observed for single earthquakes. However, how and when segmentation affects fault behavior and energy release is the basis of many outstanding questions related to the physics of faulting and seismic hazard. These include the probability for a single earthquake to rupture multiple fault segments and the effects of segmentation on earthquake magnitude, radiated seismic energy, and ground motions. Using numerical models, we quantify components of the earthquake energy budget, including the tectonic work acting externally on the system, the energy of internal rock strain, the energy required to overcome fault strength and initiate slip, the energy required to overcome frictional resistance during slip, and the radiated seismic energy. We compare the energy budgets of systems of two en echelon fault segments with various spacing that include both releasing and restraining steps. First, we allow the fault segments to fail simultaneously and capture the effects of segmentation geometry on the earthquake energy budget and on the efficiency with which applied displacement is accommodated. Assuming that higher efficiency correlates with higher probability for a single, larger earthquake, this approach has utility for assessing the seismic hazard of segmented faults. Second, we nucleate slip along a weak portion of one fault segment and let the quasi-static rupture propagate across the system. Allowing fractures to form near faults in these models shows that damage develops within releasing steps and promotes slip along the second fault, while damage develops outside of restraining steps and can prohibit slip along the second fault. Work is consumed in both the propagation of and frictional slip along these new fractures, impacting the energy available

  19. Finite element models of earthquake cycles in mature strike-slip fault zones

    Science.gov (United States)

    Lynch, John Charles

    The research presented in this dissertation is on the subject of strike-slip earthquakes and the stresses that build and release in the Earth's crust during earthquake cycles. Numerical models of these cycles in a layered elastic/viscoelastic crust are produced using the finite element method. A fault that alternately sticks and slips poses a particularly challenging problem for numerical implementation, and a new contact element dubbed the "Velcro" element was developed to address this problem (Appendix A). Additionally, the finite element code used in this study was bench-marked against analytical solutions for some simplified problems (Chapter 2), and the resolving power was tested for the fault region of the models (Appendix B). With the modeling method thus developed, there are two main questions posed. First, in Chapter 3, the effect of a finite-width shear zone is considered. By defining a viscoelastic shear zone beneath a periodically slipping fault, it is found that shear stress concentrates at the edges of the shear zone and thus causes the stress tensor to rotate into non-Andersonian orientations. Several methods are used to examine the stress patterns, including the plunge angles of the principal stresses and a new method that plots the stress tensor in a manner analogous to seismic focal mechanism diagrams. In Chapter 4, a simple San Andreas-like model is constructed, consisting of two great earthquake producing faults separated by a freely-slipping shorter fault. The model inputs of lower crustal viscosity, fault separation distance, and relative breaking strengths are examined for their effect on fault communication. It is found that with a lower crustal viscosity of 1018 Pa s (in the lower range of estimates for California), the two faults tend to synchronize their earthquake cycles, even in the cases where the faults have asymmetric breaking strengths. These models imply that postseismic stress transfer over hundreds of kilometers may play a

  20. The morphology of strike-slip faults - Examples from the San Andreas Fault, California

    Science.gov (United States)

    Bilham, Roger; King, Geoffrey

    1989-01-01

    The dilatational strains associated with vertical faults embedded in a horizontal plate are examined in the framework of fault kinematics and simple displacement boundary conditions. Using boundary element methods, a sequence of examples of dilatational strain fields associated with commonly occurring strike-slip fault zone features (bends, offsets, finite rupture lengths, and nonuniform slip distributions) is derived. The combinations of these strain fields are then used to examine the Parkfield region of the San Andreas fault system in central California.

  1. Using an Earthquake Simulator to Model Tremor Along a Strike Slip Fault

    Science.gov (United States)

    Cochran, E. S.; Richards-Dinger, K. B.; Kroll, K.; Harrington, R. M.; Dieterich, J. H.

    2013-12-01

    We employ the earthquake simulator, RSQSim, to investigate the conditions under which tremor occurs in the transition zone of the San Andreas fault. RSQSim is a computationally efficient method that uses rate- and state- dependent friction to simulate a wide range of event sizes for long time histories of slip [Dieterich and Richards-Dinger, 2010; Richards-Dinger and Dieterich, 2012]. RSQSim has been previously used to investigate slow slip events in Cascadia [Colella et al., 2011; 2012]. Earthquakes, tremor, slow slip, and creep occurrence are primarily controlled by the rate and state constants a and b and slip speed. We will report the preliminary results of using RSQSim to vary fault frictional properties in order to better understand rupture dynamics in the transition zone using observed characteristics of tremor along the San Andreas fault. Recent studies of tremor along the San Andreas fault provide information on tremor characteristics including precise locations, peak amplitudes, duration of tremor episodes, and tremor migration. We use these observations to constrain numerical simulations that examine the slip conditions in the transition zone of the San Andreas Fault. Here, we use the earthquake simulator, RSQSim, to conduct multi-event simulations of tremor for a strike slip fault modeled on Cholame section of the San Andreas fault. Tremor was first observed on the San Andreas fault near Cholame, California near the southern edge of the 2004 Parkfield rupture [Nadeau and Dolenc, 2005]. Since then, tremor has been observed across a 150 km section of the San Andreas with depths between 16-28 km and peak amplitudes that vary by a factor of 7 [Shelly and Hardebeck, 2010]. Tremor episodes, comprised of multiple low frequency earthquakes (LFEs), tend to be relatively short, lasting tens of seconds to as long as 1-2 hours [Horstmann et al., in review, 2013]; tremor occurs regularly with some tremor observed almost daily [Shelly and Hardebeck, 2010; Horstmann

  2. Role of N-S strike-slip faulting in structuring of north-eastern Tunisia; geodynamic implications

    Science.gov (United States)

    Arfaoui, Aymen; Soumaya, Abdelkader; Ben Ayed, Noureddine; Delvaux, Damien; Ghanmi, Mohamed; Kadri, Ali; Zargouni, Fouad

    2017-05-01

    Three major compressional events characterized by folding, thrusting and strike-slip faulting occurred in the Eocene, Late Miocene and Quaternary along the NE Tunisian domain between Bou Kornine-Ressas-Msella and Cap Bon Peninsula. During the Plio-Quaternary, the Grombalia and Mornag grabens show a maximum of collapse in parallelism with the NNW-SSE SHmax direction and developed as 3rd order distensives zones within a global compressional regime. Using existing tectonic and geophysical data supplemented by new fault-kinematic observations, we show that Cenozoic deformation of the Mesozoic sedimentary sequences is dominated by first order N-S faults reactivation, this sinistral wrench system is responsible for the formation of strike-slip duplexes, thrusts, folds and grabens. Following our new structural interpretation, the major faults of N-S Axis, Bou Kornine-Ressas-Messella (MRB) and Hammamet-Korbous (HK) form an N-S first order compressive relay within a left lateral strike-slip duplex. The N-S master MRB fault is dominated by contractional imbricate fans, while the parallel HK fault is characterized by a trailing of extensional imbricate fans. The Eocene and Miocene compression phases in the study area caused sinistral strike-slip reactivation of pre-existing N-S faults, reverse reactivation of NE-SW trending faults and normal-oblique reactivation of NW-SE faults, creating a NE-SW to N-S trending system of east-verging folds and overlaps. Existing seismic tomography images suggest a key role for the lithospheric subvertical tear or STEP fault (Slab Transfer Edge Propagator) evidenced below this region on the development of the MRB and the HK relay zone. The presence of extensive syntectonic Pliocene on top of this crustal scale fault may be the result of a recent lithospheric vertical kinematic of this STEP fault, due to the rollback and lateral migration of the Calabrian slab eastward.

  3. A Possible Differentially Shortened Strike-slip Plate Boundary: the Okhotsk Plate Example.

    Science.gov (United States)

    Hindle, D.; Egorov, V.; Mackey, K. G.; Fujita, K.

    2004-12-01

    The Okhotsk plate has been postulated based on a combination of GPS geodetic inversions (REVEL1), seimsicity, geologic and lineament data. Lying between the North American and Eurasian plates, its northwestern corner would appear to be undergoing compression in a scissors motion between the two bounding plates. Extrusion tectonics along multiple, large strike-slip faults within the Okhotsk plate itself have been suggested to allow the escape of material away from the apex of Eurasia-North America. The plate boundary between Okhotsk and North America has been suggested to be diffuse, based on widely scattered minor seismicity. However, the large, left lateral, Ulakhan fault has also been suggested as a candidate plate boundary. We present field geological and geomorphological evidence of the partitioning of deformation between the Ulakhan fault, and several parallel and oblique, linked faults. The Ulakhan fault strand appears to have a maximum displacement of 24 km based on river valley offsets and closing large pull apart basins. Some of the displacement from the Ulakhan fault appears relayed into the plate margin along oblique trending, thrust/oblique slip faults. Estimated shortening over these faults is equivalent to the amount of shortening relayed into the plate margin from the plate boundary. There may be several thrust/oblique slip faults along the Ulakhan fault, which leads to the interesting situation of a segmented, strike-slip plate boundary being actively shortened in a margin parallel direction. This may be the result of postulated extrusion of the Okhotsk plate due to North America/Eurasia convergence. Such a situation would have important consequences for the interpretation of GPS data in a plate tectonic context.

  4. San Andreas-sized Strike-slip Fault on Europa

    Science.gov (United States)

    1998-01-01

    This mosaic of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, about the size of the California portion of the San Andreas fault, which runs from the California-Mexico border north to the San Francisco Bay. In a strike-slip fault, two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. Overall motion along the fault seems to have followed a continuous narrow crack along the feature's entire length, with a path resembling steps on a staircase crossing zones that have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. The fault's opposite sides can be reconstructed like a puzzle, matching the shape of the sides and older, individual cracks and ridges broken by its movements. [figure removed for brevity, see original site] The red line marks the once active central crack of the fault. The black line outlines the fault zone, including material accumulated in the regions which have been pulled apart. Bends in the fault have allowed the surface to be pulled apart. This process created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling-apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, in Death Valley and the Dead Sea. In those cases, the pulled-apart regions can include upwelled materials, but may be filled mostly by sedimentary and eroded material from above. One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. Tidal tension opens the fault and

  5. Carpathian Shear Corridor – A strike-slip boundary of an extruded crustal segment

    Czech Academy of Sciences Publication Activity Database

    Marko, F.; Andriessen, P.A.M.; Tomek, Č.; Bezák, V.; Fojtíková, Lucia; Bošanský, M.; Piovarči, M.; Reichenwalder, P.

    703-704, APR 22 (2017), s. 119-134 ISSN 0040-1951 Grant - others:Slovak Foundation Grant(SK) VEGA 2/0188/15 Institutional support: RVO:67985891 Keywords : extrusion * Neo-alpine evolution * strike-slip faulting * uplift history * Western Carpathians Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Geology Impact factor: 2.693, year: 2016

  6. Evidence for slip partitioning and bimodal slip behavior on a single fault: Surface slip characteristics of the 2013 Mw7.7 Balochistan, Pakistan earthquake

    Science.gov (United States)

    Barnhart, William; Briggs, Richard; Reitman, Nadine G.; Gold, Ryan D.; Hayes, Gavin

    2015-01-01

    Deformation is commonly accommodated by strain partitioning on multiple, independent strike-slip and dip-slip faults in continental settings of oblique plate convergence. As a corollary, individual faults tend to exhibit one sense of slip – normal, reverse, or strike-slip – until whole-scale changes in boundary conditions reactivate preexisting faults in a new deformation regime. In this study, we show that a single continental fault may instead partition oblique strain by alternatively slipping in a strike-slip or a dip-slip sense during independent fault slip events. We use 0.5 m resolution optical imagery and sub-pixel correlation analysis of the 200+ km 200+km"> 2013 Mw7.7 Balochistan, Pakistan earthquake to document co-seismic surface slip characteristics and Quaternary tectonic geomorphology along the causative Hoshab fault. We find that the 2013 earthquake, which involved a ∼6:1 strike-slip to dip-slip ratio, ruptured a structurally segmented fault. Quaternary geomorphic indicators of gross fault-zone morphology reveal both reverse-slip and strike-slip deformation in the rupture area of the 2013 earthquake that varies systematically along fault strike despite nearly pure strike-slip motion in 2013. Observations of along-strike variations in range front relief and geomorphic offsets suggest that the Hoshab fault accommodates a substantial reverse component of fault slip in the Quaternary, especially along the southern section of the 2013 rupture. We surmise that Quaternary bimodal slip along the Hoshab fault is promoted by a combination of the arcuate geometry of the Hoshab fault, the frictional weakness of the Makran accretionary prism, and time variable loading conditions from adjacent earthquakes and plate interactions.

  7. Structural characteristics and implication on tectonic evolution of the Daerbute strike-slip fault in West Junggar area, NW China

    Science.gov (United States)

    Wu, Kongyou; Pei, Yangwen; Li, Tianran; Wang, Xulong; Liu, Yin; Liu, Bo; Ma, Chao; Hong, Mei

    2018-03-01

    The Daerbute fault zone, located in the northwestern margin of the Junggar basin, in the Central Asian Orogenic Belt, is a regional strike-slip fault with a length of 400 km. The NE-SW trending Daerbute fault zone presents a distinct linear trend in plain view, cutting through both the Zair Mountain and the Hala'alate Mountain. Because of the intense contraction and shearing, the rocks within the fault zone experienced high degree of cataclasis, schistosity, and mylonization, resulting in rocks that are easily eroded to form a valley with a width of 300-500 m and a depth of 50-100 m after weathering and erosion. The well-exposed outcrops along the Daerbute fault zone present sub-horizontal striations and sub-vertical fault steps, indicating sub-horizontal shearing along the observed fault planes. Flower structures and horizontal drag folds are also observed in both the well-exposed outcrops and high-resolution satellite images. The distribution of accommodating strike-slip splay faults, e.g., the 973-pluton fault and the Great Jurassic Trough fault, are in accordance with the Riedel model of simple shear. The seismic and time-frequency electromagnetic (TFEM) sections also demonstrate the typical strike-slip characteristics of the Daerbute fault zone. Based on detailed field observations of well-exposed outcrops and seismic sections, the Daerbute fault can be subdivided into two segments: the western segment presents multiple fault cores and damage zones, whereas the eastern segment only presents a single fault core, in which the rocks experienced a higher degree of rock cataclasis, schistosity, and mylonization. In the central overlapping portion between the two segments, the sediments within the fault zone are primarily reddish sandstones, conglomerates, and some mudstones, of which the palynological tests suggest middle Permian as the timing of deposition. The deformation timing of the Daerbute fault was estimated by integrating the depocenters' basinward

  8. Magma storage in a strike-slip caldera.

    Science.gov (United States)

    Saxby, J; Gottsmann, J; Cashman, K; Gutiérrez, E

    2016-07-22

    Silicic calderas form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in caldera-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango caldera, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the caldera is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions.

  9. A note on 2-D lithospheric deformation due to a blind strike-slip fault

    Indian Academy of Sciences (India)

    mic deformation. Several researchers have devel- oped models of coseismic lithospheric deformation. Rybicki (1971) found a closed-form analytical solu- tion for the problem of a long vertical strike-slip fault in a two-layer model of the earth. Chinnery and Jovanovich (1972) extended the solution to a three-layer model.

  10. Source study of the Jan Mayen transform fault strike-slip earthquakes

    Science.gov (United States)

    Rodríguez-Pérez, Q.; Ottemöller, L.

    2014-07-01

    Seismic source parameters of oceanic transform zone earthquakes have been relatively poorly studied. Previous studies showed that this type of earthquakes has unique characteristics such as not only the relatively common occurrence of slow events with weak seismic radiation at high frequencies but also the occurrence of some events that have high apparent stress indicating strong high frequency radiation. We studied 5 strike-slip earthquakes in the Jan Mayen fracture zone with magnitudes in the range of 5.9 centroid time delay compared to other oceanic transform fault earthquakes.

  11. Holocene paleoearthquakes on the strike-slip Porters Pass Fault, Canterbury, New Zealand

    International Nuclear Information System (INIS)

    Howard, M.; Nicol, A.; Campbell, J.; Pettinga, J.R.

    2005-01-01

    The Porters Pass Fault comprises a series of discontinuous Holocene active traces which extend for c. 40 km between the Rakaia and Waimakariri Rivers in the foothills of the Southern Alps. There have been no historical earthquakes on the Porters Pass Fault (i.e., within the last 150 yr), and the purpose of this paper is to establish the timing and magnitudes of displacements on the fault at the ground surface during Holocene paleoearthquakes. Displaced geomorphic features (e.g., relict streams, stream channels, and ridge crests), measured using either tape measure (n = 20) or surveying equipment (n = 5), range from 5.5 to 33 m right lateral strike slip and are consistent with six earthquakes characterised by slip per event of c. 5-7 m. The timing of these earthquakes is constrained by radiocarbon dates from four trenches excavated across the fault and two auger sites from within swamps produced by ponding of drainage along the fault scarp. These data indicate markedly different Holocene earthquake histories along the fault length separated by a behavioural segment boundary near Lake Coleridge. On the eastern segment at least six Holocene earthquakes were identified at 8400-9000, 5700-6700, 4500-6000, 2300-2500, 800-1100, and 500-600 yr BP, producing an average recurrence interval of c. 1500 yr. On the western segment of the fault in the Rakaia River valley, a single surface-rupturing earthquake displaced Acheron Advance glacial deposits (c.10,000-14,000 yr in age) and may represent the southward continuation of the 2300-2500 yr event identified on the eastern segment. These data suggest Holocene slip rates of 3.2-4.1 mm/yr and 0.3-0.9 mm/yr on the eastern and western sections of the fault, respectively. Displacement and timing data suggest that earthquakes ruptured the western segment of the fault in no more than one-sixth of cases and that for a sample period of 10,000 yr the recurrence intervals were not characteristic. (auth). 45 refs., 10 figs., 3 tabs

  12. A note on 2-D lithospheric deformation due to a blind strike-slip fault

    Indian Academy of Sciences (India)

    Analytical solution for the problem of a surface-breaking long strike-slip fault in an elastic layer overlying an elastic half-space is well known. The purpose of this note is to obtain the corresponding solution for a blind fault. Since the solution is valid for arbitrary values of the fault-depth and the dip angle, the effects of these ...

  13. Stress near geometrically complex strike-slip faults - Application to the San Andreas fault at Cajon Pass, southern California

    Science.gov (United States)

    Saucier, Francois; Humphreys, Eugene; Weldon, Ray, II

    1992-01-01

    A model is presented to rationalize the state of stress near a geometrically complex major strike-slip fault. Slip on such a fault creates residual stresses that, with the occurrence of several slip events, can dominate the stress field near the fault. The model is applied to the San Andreas fault near Cajon Pass. The results are consistent with the geological features, seismicity, the existence of left-lateral stress on the Cleghorn fault, and the in situ stress orientation in the scientific well, found to be sinistral when resolved on a plane parallel to the San Andreas fault. It is suggested that the creation of residual stresses caused by slip on a wiggle San Andreas fault is the dominating process there.

  14. Rupture model of the 2015 M7.2 Sarez, Central Pamir, earthquake and the importance of strike-slip faulting in the Pamir interior

    Science.gov (United States)

    Metzger, S.; Schurr, B.; Schoene, T.; Zhang, Y.; Sudhaus, H.

    2016-12-01

    The Pamir mountain range, located in the Northwest of the India-Asia collision zone, accommodates approximately one third of the northward advance of the Indian continent at this longitude (i.e. 34 mm/yr) mostly by shortening at its northern thrust system. Geodetic and seismic data sets reveal here a narrow zone of high deformation and M7+ earthquakes of mostly thrust type with some dextral strike-slip faulting observed, too. The Pamir interior shows sinistral strike-slip and normal faulting indicating north-south compression and east-west extension. In this tectonic setting the two largest instrumentally recorded earthquakes, the M7+ 1911 and 2015 earthquake events in the central Pamir occurred with left-lateral shear along a NE-SW rupture plane. We present the co-seismic deformation field of the 2015 earthquake observed by Radar satellite interferometry (InSAR), SAR amplitude offsets and high-rate Global Positioning System (GPS). The InSAR and offset results reveal that the earthquake created a 50 km long surface rupture with maximum left-lateral offsets of more than two meters on a yet unmapped fault trace of the Sarez Karakul Fault System (SKFS). We further derive a distributed slip-model including a thorough model parameter uncertainty study. Using a two-step approach to first find the optimal rupture geometry and then invert for slip on discrete patches, we show that a data-driven patch resolution produces yields a better representation of the near-surface slip and an increased slip precision than a uniform patch approach without increasing the number of parameters and thus calculation time. Our best-fit model yields a sub-vertical fault plane with a strike of N39.5 degrees and a rupture area of 80 x 40 km2 with a maximum slip of 2 meters in the upper 10 km of the crust near the surface rupture. The 1911 and 2015 earthquakes demonstrate the importance of sinistral strike-slip faulting on the SKFS, contributing both to shear between the western and eastern

  15. Tsunamis from strike-slip earthquakes in the Wharton Basin, northeast Indian Ocean: March 2016 Mw7.8 event and its relationship with the April 2012 Mw 8.6 event

    Science.gov (United States)

    Heidarzadeh, Mohammad; Harada, Tomoya; Satake, Kenji; Ishibe, Takeo; Takagawa, Tomohiro

    2017-12-01

    The Wharton Basin, off southwest Sumatra, ruptured to a large intraplate left-lateral strike-slip Mw 7.8 earthquake on 2016 March 2. The epicentre was located ∼800 km to the south of another similar-mechanism intraplate Mw 8.6 earthquake in the same basin on 2012 April 11. Small tsunamis from these strike-slip earthquakes were registered with maximum amplitudes of 0.5-1.5 cm on DARTs and 1-19 cm on tide gauges for the 2016 event, and the respective values of 0.5-6 and 6-40 cm for the 2012 event. By using both teleseismic body waves and tsunami observations of the 2016 event, we obtained optimum slip models with rupture velocity (Vr) in the range of 2.8-3.6 km s-1 belonging to both EW and NS faults. While the EW fault plane cannot be fully ruled out, we chose the best model as the NS fault plane with a Vr of 3.6 km s-1, a maximum slip of 7.7 m and source duration of 33 s. The tsunami energy period bands were 4-15 and 7-24 min for the 2016 and 2012 tsunamis, respectively, reflecting the difference in source sizes. Seismicity in the Wharton Basin is dominated by large strike-slip events including the 2012 (Mw 8.6 and 8.2) and 2016 (Mw 7.8) events, indicating that these events are possible tsunami sources in the Wharton Basin. Cumulative number and cumulative seismic-moment curves revealed that most earthquakes are of strike-slip mechanisms and the largest seismic-moment is provided by the strike-slip earthquakes in this basin.

  16. The role of the East Asian active margin in widespread extensional and strike-slip deformation in East Asia

    NARCIS (Netherlands)

    Schellart, Wouter P.; Lister, G. S.

    2005-01-01

    East Asia is a region of widespread deformation, dominated by normal and strike-slip faults. Deformation has been interpreted to result from extrusion tectonics related to the India-Eurasia collision, which started in the Early Eocene. In East and SE China, however, deformation started earlier than

  17. The rupture process of the Manjil, Iran earthquake of 20 june 1990 and implications for intraplate strike-slip earthquakes

    Science.gov (United States)

    Choy, G.L.; Zednik, J.

    1997-01-01

    In terms of seismically radiated energy or moment release, the earthquake of 20 January 1990 in the Manjil Basin-Alborz Mountain region of Iran is the second largest strike-slip earthquake to have occurred in an intracontinental setting in the past decade. It caused enormous loss of life and the virtual destruction of several cities. Despite a very large meizoseismal area, the identification of the causative faults has been hampered by the lack of reliable earthquake locations and conflicting field reports of surface displacement. Using broadband data from global networks of digitally recording seismographs, we analyse broadband seismic waveforms to derive characteristics of the rupture process. Complexities in waveforms generated by the earthquake indicate that the main shock consisted of a tiny precursory subevent followed in the next 20 seconds by a series of four major subevents with depths ranging from 10 to 15 km. The focal mechanisms of the major subevents, which are predominantly strike-slip, have a common nodal plane striking about 285??-295??. Based on the coincidence of this strike with the dominant tectonic fabric of the region we presume that the EW striking planes are the fault planes. The first major subevent nucleated slightly south of the initial precursor. The second subevent occurred northwest of the initial precursor. The last two subevents moved progressively southeastward of the first subevent in a direction collinear with the predominant strike of the fault planes. The offsets in the relative locations and the temporal delays of the rupture subevents indicate heterogeneous distribution of fracture strength and the involvement of multiple faults. The spatial distribution of teleseismic aftershocks, which at first appears uncorrelated with meizoseismal contours, can be decomposed into stages. The initial activity, being within and on the periphery of the rupture zone, correlates in shape and length with meizoseismal lines. In the second stage

  18. Structural analysis of S-wave seismics around an urban sinkhole: evidence of enhanced dissolution in a strike-slip fault zone

    Science.gov (United States)

    Wadas, Sonja H.; Tanner, David C.; Polom, Ulrich; Krawczyk, Charlotte M.

    2017-12-01

    In November 2010, a large sinkhole opened up in the urban area of Schmalkalden, Germany. To determine the key factors which benefited the development of this collapse structure and therefore the dissolution, we carried out several shear-wave reflection-seismic profiles around the sinkhole. In the seismic sections we see evidence of the Mesozoic tectonic movement in the form of a NW-SE striking, dextral strike-slip fault, known as the Heßleser Fault, which faulted and fractured the subsurface below the town. The strike-slip faulting created a zone of small blocks ( sinkholes and dissolution-induced depressions. Since the processes are still ongoing, the occurrence of a new sinkhole cannot be ruled out. This case study demonstrates how S-wave seismics can characterize a sinkhole and, together with geological information, can be used to study the processes that result in sinkhole formation, such as a near-surface fault zone located in soluble rocks. The more complex the fault geometry and interaction between faults, the more prone an area is to sinkhole occurrence.

  19. Late Quaternary strike-slip along the Taohuala Shan-Ayouqi fault zone and its tectonic implications in the Hexi Corridor and the southern Gobi Alashan, China

    Science.gov (United States)

    Yu, Jing-xing; Zheng, Wen-jun; Zhang, Pei-zhen; Lei, Qi-yun; Wang, Xu-long; Wang, Wei-tao; Li, Xin-nan; Zhang, Ning

    2017-11-01

    The Hexi Corridor and the southern Gobi Alashan are composed of discontinuous a set of active faults with various strikes and slip motions that are located to the north of the northern Tibetan Plateau. Despite growing understanding of the geometry and kinematics of these active faults, the late Quaternary deformation pattern in the Hexi Corridor and the southern Gobi Alashan remains controversial. The active E-W trending Taohuala Shan-Ayouqi fault zone is located in the southern Gobi Alashan. Study of the geometry and nature of slip along this fault zone holds crucial value for better understanding the regional deformation pattern. Field investigations combined with high-resolution imagery show that the Taohuala Shan fault and the E-W trending faults within the Ayouqi fault zone (F2 and F5) are left-lateral strike-slip faults, whereas the NW or WNW-trending faults within the Ayouqi fault zone (F1 and F3) are reverse faults. We collected Optically Stimulated Luminescence (OSL) and cosmogenic exposure age dating samples from offset alluvial fan surfaces, and estimated a vertical slip rate of 0.1-0.3 mm/yr, and a strike-slip rate of 0.14-0.93 mm/yr for the Taohuala Shan fault. Strata revealed in a trench excavated across the major fault (F5) in the Ayouqi fault zone and OSL dating results indicate that the most recent earthquake occurred between ca. 11.05 ± 0.52 ka and ca. 4.06 ± 0.29 ka. The geometry and kinematics of the Taohuala Shan-Ayouqi fault zone enable us to build a deformation pattern for the entire Hexi Corridor and the southern Gobi Alashan, which suggest that this region experiences northeastward oblique extrusion of the northern Tibetan Plateau. These left-lateral strike-slip faults in the region are driven by oblique compression but not associated with the northeastward extension of the Altyn Tagh fault.

  20. The Damage and Geochemical Signature of a Crustal Scale Strike-Slip Fault Zone

    Science.gov (United States)

    Gomila, R.; Mitchell, T. M.; Arancibia, G.; Jensen Siles, E.; Rempe, M.; Cembrano, J. M.; Faulkner, D. R.

    2013-12-01

    Fluid-flow migration in the upper crust is strongly controlled by fracture network permeability and connectivity within fault zones, which can lead to fluid-rock chemical interaction represented as mineral precipitation in mesh veins and/or mineralogical changes (alteration) of the host rock. While the dimensions of fault damage zones defined by fracture intensity is beginning to be better understood, how such dimensions compare to the size of alteration zones is less well known. Here, we show quantitative structural and chemical analyses as a function of distance from a crustal-scale strike-slip fault in the Atacama Fault System, Northern Chile, to compare fault damage zone characteristics with its geochemical signature. The Jorgillo Fault (JF) is a ca. 18 km long NNW striking strike-slip fault cutting Mesozoic rocks with sinistral displacement of ca. 4 km. In the study area, the JF cuts through orthogranulitic and gabbroic rocks at the west (JFW) and the east side (JFE), respectively. A 200 m fault perpendicular transect was mapped and sampled for structural and XRF analyses of the core, damage zone and protolith. The core zone consists of a ca. 1 m wide cataclasite zone bounded by two fault gouge zones ca. 40 cm. The damage zone width defined by fracture density is ca. 50 m wide each side of the core. The damage zone in JFW is characterized by NW-striking subvertical 2 cm wide cataclastic rocks and NE-striking milimetric open fractures. In JFE, 1-20 mm wide chlorite, quartz-epidote and quartz-calcite veins, cut the gabbro. Microfracture analysis in JFW reveal mm-wide cataclasitic/ultracataclasitic bands with clasts of protolith and chlorite orientated subparallel to the JF in the matrix, calcite veins in a T-fractures orientation, and minor polidirectional chlorite veins. In JFE, chlorite filled conjugate fractures with syntaxial growth textures and evidence for dilational fracturing processes are seen. Closest to the core, calcite veins crosscut chlorite veins

  1. The 2015 M7.2 Sarez, Central Pamir, Earthquake And The Importance Of Strike-Slip Faulting In The Pamir Interior: Insights From Geodesy And Field Observations

    Science.gov (United States)

    Metzger, Sabrina; Schurr, Bernd; Ratschbacher, Lothar; Schöne, Tilo; Kufner, Sofia-Katerina; Zhang, Yong; Sudhaus, Henriette

    2017-04-01

    The Pamir mountain range, located in the Northwest of the India-Asia collision zone, accommodates approximately one third of the northward advance of the Indian continent at this longitude (i. e. ˜34 mm/yr) mostly by shortening at its northern thrust system. Geodetic and seismic data sets reveal here a narrow zone of high deformation and M7+ earthquakes of mostly thrust type with some dextral strike-slip faulting observed, too. The Pamir interior shows sinistral strike-slip and normal faulting indicating north-south compression and east-west extension. In this tectonic setting the two largest instrumentally recorded earthquakes, the M7+ 1911 and 2015 earthquake events in the central Pamir occurred with left-lateral shear along a NE-SW rupture plane. We present the co-seismic deformation field of the 2015 earthquake observed by radar satellite interferometry (InSAR), SAR amplitude pixel offsets and high-rate Global Positioning System (GPS). The InSAR and pixel offset results suggest a 50+ km long rupture with sinistral fault offsets at the surface of more than 2 m on a yet unmapped fault trace of the Sarez Karakul Fault System (SKFS). A distributed slip model with a data-driven slip patch resolution yields a sub-vertical fault plane with a strike of N39.5 degrees and a rupture area of ˜80 x 40 km with a maximum slip of 2 m in the upper 10 km of the crust near the surface rupture. Field observations collected some nine months after the earthquake confirm the rupture mechanism, surface trace location and fault offset measurements as constrained by geodetic data. Diffuse deformation was observed across a 1-2 km wide zone, hosting primary fractures sub-parallel to the rupture strike with offsets of 2 m and secondary, en echelon fractures including Riedel shears and hybrid fractures often related to gravitational mass movements. The 1911 and 2015 earthquakes demonstrate the importance of sinistral strike-slip faulting on the SKFS, contributing both to shear between the

  2. The 2015 Mw7.2 Sarez Strike-Slip Earthquake in the Pamir Interior: Response to the Underthrusting of India's Western Promontory

    Science.gov (United States)

    Metzger, Sabrina; Schurr, Bernd; Ratschbacher, Lothar; Sudhaus, Henriette; Kufner, Sofia-Katerina; Schöne, Tilo; Zhang, Yong; Perry, Mason; Bendick, Rebecca

    2017-11-01

    The Pamir orogen, Central Asia, is the result of the ongoing northward advance of the Indian continent causing shortening inside Asia. Geodetic and seismic data place the most intense deformation along the northern rim of the Pamir, but the recent 7 December 2015, Mw7.2 Sarez earthquake occurred in the Pamir's interior. We present a distributed slip model of this earthquake using coseismic geodetic data and postseismic field observations. The earthquake ruptured an ˜80 km long, subvertical, sinistral fault consisting of three right-stepping segments from the surface to ˜30 km depth with a maximum slip of three meters in the upper 10 km of the crust. The coseismic slip model agrees well with en échelon secondary surface breaks that are partly influenced by liquefaction-induced mass movements. These structures reveal up to 2 m of sinistral offset along the northern, low-offset segment of modeled rupture. The 2015 event initiated close to the presumed epicenter of the 1911 Mw˜7.3 Lake Sarez earthquake, which had a similar strike-slip mechanism. These earthquakes highlight the importance of NE trending sinistral faults in the active tectonics of the Pamir. Strike-slip deformation accommodates shear between the rapidly northward moving eastern Pamir and the Tajik basin in the west and is part of the westward (lateral) extrusion of thickened Pamir plateau crust into the Tajik basin. The Sarez-Karakul fault system and the two large Sarez earthquakes likely are crustal expressions of the underthrusting of the northwestern leading edge of the Indian mantle lithosphere beneath the Pamir.

  3. Three-dimensional shuffling of horses in a strike-slip duplex: an example from the Lambertville sill, New Jersey

    Science.gov (United States)

    Laney, Stephen E.; Gates, Alexander E.

    1996-06-01

    Detailed analysis of a dextral strike-slip duplex within the relatively isotropic rocks of the Lambertville sill, New Jersey indicates that horses have experienced vertical, horizontal and oblique movements resulting from extrusional shuffling within a restraining bend. This is the first documentation of the three-dimensional movement of horses within a strike-slip duplex. Deformation within the duplex shows a complex system of early synthetic fractures and reverse faults followed by antithetic fractures which dissect previously continuous slab-shaped horses into diamond-shaped lenses. Most faults are oblique slip. Antithetic fault movements and clockwise rigid rotation of horses dominate the south half of the duplex and synthetic movements and counterclockwise rotations dominate the north half. Slickenline plunges on curved horse-bounding fault surfaces within the duplex range from nearly horizontal to 40° resulting in both lateral movements (middle) to normal movements (tails) on a single horse. Curved slickensides commonly have opposite senses of movement on either side of individual horses indicating relative emergence or submergence. Such a geometry could also result from a group of horses moving in the same oblique direction but at different rates. These complex extrusional-type movements were observed in both cross-sectional and plan views. The net result of the movements is a contraction or flattening of the duplex normal to the bounding faults. The horses shifted to accommodate this flattening as overall displacement was transferred between the bounding faults along curved internal faults.

  4. The geometry of the active strike-slip El Tigre Fault, Precordillera of San Juan, Central-Western Argentina: integrating resistivity surveys with structural and geomorphological data

    Science.gov (United States)

    Fazzito, Sabrina Y.; Cortés, José M.; Rapalini, Augusto E.; Terrizzano, Carla M.

    2013-07-01

    The geometry and related geomorphological features of the right-lateral strike-slip El Tigre Fault, one of the main morphostructural discontinuities in the Central-Western Precordillera of Argentina, were investigated. Achievements of this survey include: recognition of structural and geometrical discontinuities along the fault trace, identification and classification of landforms associated with local transpressional and transtensional sectors, observation of significant changes in the fault strike and detection of right and left bends of different wavelength. In the Central Segment of the El Tigre Fault, 2D electrical resistivity tomography surveys were carried out across the fault zone. The resistivity imaging permitted to infer the orientation of the main fault surface, the presence of blind fault branches along the fault zone, tectonic tilting of the Quaternary sedimentary cover, subsurface structure of pressure ridges and depth to the water table. Based on this information, it is possible to characterize the El Tigre Fault also as an important hydro-geological barrier. Our survey shows that the main fault surface changes along different segments from a high-angle to a subvertical setting whilst the vertical-slip component is either reverse or normal, depending on the local transpressive or transtensive regime induced by major bends along the trace. These local variations are expressed as sections of a few kilometres in length with relatively homogeneous behaviour and frequently separated by oblique or transversal structures.

  5. Long term fault system reorganization of convergent and strike-slip systems

    Science.gov (United States)

    Cooke, M. L.; McBeck, J.; Hatem, A. E.; Toeneboehn, K.; Beyer, J. L.

    2017-12-01

    Laboratory and numerical experiments representing deformation over many earthquake cycles demonstrate that fault evolution includes episodes of fault reorganization that optimize work on the fault system. Consequently, the mechanical and kinematic efficiencies of fault systems do not increase monotonically through their evolution. New fault configurations can optimize the external work required to accommodate deformation, suggesting that changes in system efficiency can drive fault reorganization. Laboratory evidence and numerical results show that fault reorganization within accretion, strike-slip and oblique convergent systems is associated with increasing efficiency due to increased fault slip (frictional work and seismic energy) and commensurate decreased off-fault deformation (internal work and work against gravity). Between episodes of fault reorganization, fault systems may become less efficient as they produce increasing off fault deformation. For example, laboratory and numerical experiments show that the interference and interaction between different fault segments may increase local internal work or that increasing convergence can increase work against gravity produced by a fault system. This accumulation of work triggers fault reorganization as stored work provides the energy required to grow new faults that reorganize the system to a more efficient configuration. The results of laboratory and numerical experiments reveal that we should expect crustal fault systems to reorganize following periods of increasing inefficiency, even in the absence of changes to the tectonic regime. In other words, fault reorganization doesn't require a change in tectonic loading. The time frame of fault reorganization depends on fault system configuration, strain rate and processes that relax stresses within the crust. For example, stress relaxation may keep pace with stress accumulation, which would limit the increase in the internal work and gravitational work so that

  6. Seafloor observations indicate spatial separation of coseismic and postseismic slips in the 2011 Tohoku earthquake

    Science.gov (United States)

    Iinuma, Takeshi; Hino, Ryota; Uchida, Naoki; Nakamura, Wataru; Kido, Motoyuki; Osada, Yukihito; Miura, Satoshi

    2016-01-01

    Large interplate earthquakes are often followed by postseismic slip that is considered to occur in areas surrounding the coseismic ruptures. Such spatial separation is expected from the difference in frictional and material properties in and around the faults. However, even though the 2011 Tohoku Earthquake ruptured a vast area on the plate interface, the estimation of high-resolution slip is usually difficult because of the lack of seafloor geodetic data. Here using the seafloor and terrestrial geodetic data, we investigated the postseismic slip to examine whether it was spatially separated with the coseismic slip by applying a comprehensive finite-element method model to subtract the viscoelastic components from the observed postseismic displacements. The high-resolution co- and postseismic slip distributions clarified the spatial separation, which also agreed with the activities of interplate and repeating earthquakes. These findings suggest that the conventional frictional property model is valid for the source region of gigantic earthquakes. PMID:27853138

  7. The Trans-Rocky Mountain Fault System - A Fundamental Precambrian Strike-Slip System

    Science.gov (United States)

    Sims, P.K.

    2009-01-01

    Recognition of a major Precambrian continental-scale, two-stage conjugate strike-slip fault system - here designated as the Trans-Rocky Mountain fault system - provides new insights into the architecture of the North American continent. The fault system consists chiefly of steep linear to curvilinear, en echelon, braided and branching ductile-brittle shears and faults, and local coeval en echelon folds of northwest strike, that cut indiscriminately across both Proterozoic and Archean cratonic elements. The fault system formed during late stages of two distinct tectonic episodes: Neoarchean and Paleoproterozoic orogenies at about 2.70 and 1.70 billion years (Ga). In the Archean Superior province, the fault system formed (about 2.70-2.65 Ga) during a late stage of the main deformation that involved oblique shortening (dextral transpression) across the region and progressed from crystal-plastic to ductile-brittle deformation. In Paleoproterozoic terranes, the fault system formed about 1.70 Ga, shortly following amalgamation of Paleoproterozoic and Archean terranes and the main Paleoproterozoic plastic-fabric-producing events in the protocontinent, chiefly during sinistral transpression. The postulated driving force for the fault system is subcontinental mantle deformation, the bottom-driven deformation of previous investigators. This model, based on seismic anisotropy, invokes mechanical coupling and subsequent shear between the lithosphere and the asthenosphere such that a major driving force for plate motion is deep-mantle flow.

  8. Evidence of extensional and strike-slip deformation in the offshore Gökova-Kos area affected by the July 2017 Mw6.6 Bodrum-Kos earthquake, eastern Aegean Sea

    Science.gov (United States)

    Ocakoğlu, Neslihan; Nomikou, Paraskevi; İşcan, Yeliz; Loreto, Maria Filomena; Lampridou, Danai

    2018-01-01

    The interpretation of new multichannel seismic profiles and previously published high-resolution swath and seismic reflection data from the Gökova Gulf and southeast of Kos Island in the eastern Aegean Sea revealed new morphotectonic features related to the July 20, 2017 Mw6.6 Bodrum-Kos earthquake offshore between Kos Island and the Bodrum Peninsula. The seafloor morphology in the northern part of the gulf is characterized by south-dipping E-W-oriented listric normal faults. These faults bend to a ENE-WSW direction towards Kos Island, and then extend parallel to the southern coastline. A left-lateral SW-NE strike-slip fault zone is mapped with segments crossing the Gökova Gulf from its northern part to south of Kos Island. This fault zone intersects and displaces the deep basins in the gulf. The basins are thus interpreted as the youngest deformed features in the study area. The strike-slip faults also produce E-W-oriented ridges between the basin segments, and the ridge-related vertical faults are interpreted as reverse faults. This offshore study reveals that the normal and strike-slip faults are well correlated with the focal mechanism solutions of the recent earthquake and general seismicity of the Gökova Gulf. Although the complex morphotectonic features could suggest that the area is under a transtensional regime, kinematic elements normally associated with a transtensional system are missing. At present, the Gökova Gulf is experiencing strike-slip motion with dominant extensional deformation, rather than transtensional deformation.

  9. Evidence of extensional and strike-slip deformation in the offshore Gökova-Kos area affected by the July 2017 Mw6.6 Bodrum-Kos earthquake, eastern Aegean Sea

    Science.gov (United States)

    Ocakoğlu, Neslihan; Nomikou, Paraskevi; İşcan, Yeliz; Loreto, Maria Filomena; Lampridou, Danai

    2018-06-01

    The interpretation of new multichannel seismic profiles and previously published high-resolution swath and seismic reflection data from the Gökova Gulf and southeast of Kos Island in the eastern Aegean Sea revealed new morphotectonic features related to the July 20, 2017 Mw6.6 Bodrum-Kos earthquake offshore between Kos Island and the Bodrum Peninsula. The seafloor morphology in the northern part of the gulf is characterized by south-dipping E-W-oriented listric normal faults. These faults bend to a ENE-WSW direction towards Kos Island, and then extend parallel to the southern coastline. A left-lateral SW-NE strike-slip fault zone is mapped with segments crossing the Gökova Gulf from its northern part to south of Kos Island. This fault zone intersects and displaces the deep basins in the gulf. The basins are thus interpreted as the youngest deformed features in the study area. The strike-slip faults also produce E-W-oriented ridges between the basin segments, and the ridge-related vertical faults are interpreted as reverse faults. This offshore study reveals that the normal and strike-slip faults are well correlated with the focal mechanism solutions of the recent earthquake and general seismicity of the Gökova Gulf. Although the complex morphotectonic features could suggest that the area is under a transtensional regime, kinematic elements normally associated with a transtensional system are missing. At present, the Gökova Gulf is experiencing strike-slip motion with dominant extensional deformation, rather than transtensional deformation.

  10. Analysis of the growth of strike-slip faults using effective medium theory

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, A.; Berryman, J.G.

    2009-10-15

    Increases in the dimensions of strike-slip faults including fault length, thickness of fault rock and the surrounding damage zone collectively provide quantitative definition of fault growth and are commonly measured in terms of the maximum fault slip. The field observations indicate that a common mechanism for fault growth in the brittle upper crust is fault lengthening by linkage and coalescence of neighboring fault segments or strands, and fault rock-zone widening into highly fractured inner damage zone via cataclastic deformation. The most important underlying mechanical reason in both cases is prior weakening of the rocks surrounding a fault's core and between neighboring fault segments by faulting-related fractures. In this paper, using field observations together with effective medium models, we analyze the reduction in the effective elastic properties of rock in terms of density of the fault-related brittle fractures and fracture intersection angles controlled primarily by the splay angles. Fracture densities or equivalent fracture spacing values corresponding to the vanishing Young's, shear, and quasi-pure shear moduli were obtained by extrapolation from the calculated range of these parameters. The fracture densities or the equivalent spacing values obtained using this method compare well with the field data measured along scan lines across the faults in the study area. These findings should be helpful for a better understanding of the fracture density/spacing distribution around faults and the transition from discrete fracturing to cataclastic deformation associated with fault growth and the related instabilities.

  11. The 2012 Strike-slip Earthquake Sequence in Black Sea and its Link to the Caucasus Collision Zone

    Science.gov (United States)

    Tseng, T. L.; Hsu, C. H.; Legendre, C. P.; Jian, P. R.; Huang, B. S.; Karakhanian, A.; Chen, C. W.

    2016-12-01

    The Black Sea formed as a back-arc basin in Late Cretaceous to Paleogene with lots of extensional features. However, the Black Sea is now tectonically stable and absent of notable earthquakes except for the coastal region. In this study we invert regional waveforms of a new seismic array to constrain the focal mechanisms and depths of the 2012/12/23 earthquake sequence occurred in northeastern Black Sea basin that can provide unique estimates on the stress field in the region. The results show that the focal mechanisms for the main shock and 5 larger aftershocks are all strike-slip faulting and resembling with each other. The main rupture fall along the vertical dipping, NW-SE trending sinistral fault indicated by the lineation of most aftershocks. The fault strike and aftershock distribution are both consistent with the Shatsky Ridge, which is continental in nature but large normal faults was created by previous subsidence. The occurrence of 2012 earthquakes can be re-activated, as strike-slip, on one of the pre-existing normal fault cutting at depth nearly 20-30 km in the extended crust. Some of the aftershocks, including a larger one occurred 5 days later, are distributed toward NE direction 20 km away from main fault zone. Those events might be triggered by the main shock along a conjugate fault, which is surprisingly at the extension of proposed transform fault perpendicular to the rift axis of eastern Black Sea Basin. The focal mechanisms also indicate that the maximum compression in northeast Black Sea is at E-W direction, completely different from the N-S compression in the Caucasus and East Turkey controlled by Arabia-Eurasia collision. The origin of E-W maximum compression is probably the same as the secondary stress inferred from earthquakes in Racha region of the Greater Caucasus.

  12. The 2014 Mw6.9 Gokceada and 2017 Mw6.3 Lesvos Earthquakes in the Northern Aegean Sea: The Transition from Right-Lateral Strike-Slip Faulting on the North Anatolian Fault to Extension in the Central Aegean

    Science.gov (United States)

    Cetin, S.; Konca, A. O.; Dogan, U.; Floyd, M.; Karabulut, H.; Ergintav, S.; Ganas, A.; Paradisis, D.; King, R. W.; Reilinger, R. E.

    2017-12-01

    The 2014 Mw6.9 Gokceada (strike-slip) and 2017 Mw6.3 Lesvos (normal) earthquakes represent two of the set of faults that accommodate the transition from right-lateral strike-slip faulting on the North Anatolian Fault (NAF) to normal faulting along the Gulf of Corinth. The Gokceada earthquake was a purely strike-slip event on the western extension of the NAF where it enters the northern Aegean Sea. The Lesvos earthquake, located roughly 200 km south of Gokceada, occurred on a WNW-ESE-striking normal fault. Both earthquakes respond to the same regional stress field, as indicated by their sub-parallel seismic tension axis and far-field coseismic GPS displacements. Interpretation of GPS-derived velocities, active faults, crustal seismicity, and earthquake focal mechanisms in the northern Aegean indicates that this pattern of complementary faulting, involving WNW-ESE-striking normal faults (e.g. Lesvos earthquake) and SW-NE-striking strike-slip faults (e.g. Gokceada earthquake), persists across the full extent of the northern Aegean Sea. The combination of these two "families" of faults, combined with some systems of conjugate left-lateral strike-slip faults, complement one another and culminate in the purely extensional rift structures that form the large Gulfs of Evvia and Corinth. In addition to being consistent with seismic and geodetic observations, these fault geometries explain the increasing velocity of the southern Aegean and Peloponnese regions towards the Hellenic subduction zone. Alignment of geodetic extension and seismic tension axes with motion of the southern Aegean towards the Hellenic subduction zone suggests a direct association of Aegean extension with subduction, possibly by trench retreat, as has been suggested by prior investigators.

  13. Paleomagnetic and structural evidence for oblique slip in a fault-related fold, Grayback monocline, Colorado

    Science.gov (United States)

    Tetreault, J.; Jones, C.H.; Erslev, E.; Larson, S.; Hudson, M.; Holdaway, S.

    2008-01-01

    Significant fold-axis-parallel slip is accommodated in the folded strata of the Grayback monocline, northeastern Front Range, Colorado, without visible large strike-slip displacement on the fold surface. In many cases, oblique-slip deformation is partitioned; fold-axis-normal slip is accommodated within folds, and fold-axis-parallel slip is resolved onto adjacent strike-slip faults. Unlike partitioning strike-parallel slip onto adjacent strike-slip faults, fold-axis-parallel slip has deformed the forelimb of the Grayback monocline. Mean compressive paleostress orientations in the forelimb are deflected 15??-37?? clockwise from the regional paleostress orientation of the northeastern Front Range. Paleomagnetic directions from the Permian Ingleside Formation in the forelimb are rotated 16??-42?? clockwise about a bedding-normal axis relative to the North American Permian reference direction. The paleostress and paleomagnetic rotations increase with the bedding dip angle and decrease along strike toward the fold tip. These measurements allow for 50-120 m of fold-axis-parallel slip within the forelimb, depending on the kinematics of strike-slip shear. This resolved horizontal slip is nearly equal in magnitude to the ???180 m vertical throw across the fold. For 200 m of oblique-slip displacement (120 m of strike slip and 180 m of reverse slip), the true shortening direction across the fold is N90??E, indistinguishable from the regionally inferred direction of N90??E and quite different from the S53??E fold-normal direction. Recognition of this deformational style means that significant amounts of strike slip can be accommodated within folds without axis-parallel surficial faulting. ?? 2008 Geological Society of America.

  14. Analogue Modeling of Oblique Convergent Strike-Slip Faulting and Application to The Seram Island, Eastern Indonesia

    Directory of Open Access Journals (Sweden)

    Benyamin Sapiie

    2014-12-01

    Full Text Available DOI:10.17014/ijog.v1i3.189Sandbox experiment is one of the types of analogue modeling in geological sciences in which the main purpose is simulating deformation style and structural evolution of the sedimentary basin.  Sandbox modeling is one of the effective ways in conducting physically modeling and evaluates complex deformation of sedimentary rocks. The main purpose of this paper is to evaluate structural geometry and deformation history of oblique convergent deformation using of integrated technique of analogue sandbox modeling applying to deformation of Seram Fold-Thrust-Belt (SFTB in the Seram Island, Eastern Indonesia. Oblique convergent strike-slip deformation has notoriously generated area with structural complex geometry and pattern resulted from role of various local parameters that control stress distributions. Therefore, a special technique is needed for understanding and solving such problem in particular to relate 3D fault geometry and its evolution. The result of four case (Case 1 to 4 modeling setting indicated that two of modeling variables clearly affected in our sandbox modeling results; these are lithological variation (mainly stratigraphy of Seram Island and pre-existing basement fault geometry (basement configuration. Lithological variation was mainly affected in the total number of faults development.  On the other hand, pre-existing basement fault geometry was highly influenced in the end results particularly fault style and pattern as demonstrated in Case 4 modeling.  In addition, this study concluded that deformation in the Seram Island is clearly best described using oblique convergent strike-slip (transpression stress system.

  15. The role of post-collisional strike-slip tectonics in the geological evolution of the late Neoproterozoic volcano-sedimentary Guaratubinha Basin, southern Brazil

    Science.gov (United States)

    Barão, Leonardo M.; Trzaskos, Barbara; Vesely, Fernando F.; de Castro, Luís Gustavo; Ferreira, Francisco J. F.; Vasconcellos, Eleonora M. G.; Barbosa, Tiago C.

    2017-12-01

    The Guaratubinha Basin is a late Neoproterozoic volcano-sedimentary basin included in the transitional-stage basins of the South American Platform. The aim of this study is to investigate its tectonic evolution through a detailed structural analysis based on remote sensing and field data. The structural and aerogeophysics data indicate that at least three major deformational events affected the basin. Event E1 caused the activation of the two main basin-bounding fault zones, the Guaratubinha Master Fault and the Guaricana Shear Zone. These structures, oriented N20-45E, are associated with well-defined right-lateral to oblique vertical faults, conjugate normal faults and vertical flow structures. Progressive transtensional deformation along the two main fault systems was the main mechanism for basin formation and the deposition of thick coarse-grained deposits close to basin-borders. The continuous opening of the basin provided intense intermediate and acid magmatism as well as deposition of volcaniclastic sediments. Event E2 characterizes generalized compression, recorded as minor thrust faults with tectonic transport toward the northwest and left-lateral activation of the NNE-SSW Palmital Shear Zone. Event E3 is related to the Mesozoic tectonism associated with the South Atlantic opening, which generated diabase dykes and predominantly right-lateral strike-slip faults oriented N10-50W. Its rhomboidal geometry with long axis parallel to major Precambrian shear zones, the main presence of high-angle, strike-slip or oblique faults, the asymmetric distribution of geological units and field evidence for concomitant Neoproterozoic magmatism and strike-slip movements are consistent with pull-apart basins reported in the literature.

  16. The 2005 - 2007 Bala (Ankara, central Turkey) earthquakes: a case study for strike-slip fault terminations

    OpenAIRE

    Esat, K.; Çivgin, B.; Kaypak, B.; Isik, V.; Ecevitoglu, B.; Seyitoglu, G.

    2014-01-01

    An intense seismic activity has been observed after the Bala (Ankara, NW central Turkey) earthquakes (30 July 2005: Mw=5.3, 20 December 2007: Mw=5.4, and 26 December 2007: Mw=5.3), continuing up to the present. The epicenters and the focal mechanism solutions of the earthquakes indicate that the right lateral strike-slip Afşar fault, trending N55-60°W, is responsible for the main shocks. The Afşar fault is thought to be the NW continuation of the Tuzgölü fault zone, which is one of the main n...

  17. Analogue modelling of a reactivated, basement controlled strike-slip zone, Sierra de Albarracín, Spain: application of sandbox modelling to polyphase deformation

    NARCIS (Netherlands)

    Merten, S.; Smit, W.G.; Nieuwland, D.A.; Rondeel, H.E.

    2006-01-01

    This paper presents the results of an analogue modelling study on the reactivation of Riedel shears generated by basement-induced sinistral strike-slip faulting. It is based on a natural example in the Sierra de Albarracín, Iberian Range (Spain). The area has a polyphase deformation history, defined

  18. The Evolution from Late Miocene West Salton Detachment Faulting to Cross-Cutting Pleistocene Oblique Strike-Slip Faults in the SW Salton Trough, Southern California

    OpenAIRE

    Steely, Alexander N.

    2006-01-01

    Field studies in the southwest Salton Trough between Yaqui Ridge and Borrego Mountain show that the West Salton detachment fault was active during the Pliocene and may have initiated during the latest Miocene. At Yaqui Ridge dominantly east-directed extension is recorded by slickenlines on the NW-striking detachment fault, and shows that the fault is actually a low-angle dextral oblique strike-slip fault. Crustal inheritance is responsible for the position of the fault at Yaqui Ridge, which r...

  19. Structural analysis of S-wave seismics around an urban sinkhole: evidence of enhanced dissolution in a strike-slip fault zone

    Directory of Open Access Journals (Sweden)

    S. H. Wadas

    2017-12-01

    Full Text Available In November 2010, a large sinkhole opened up in the urban area of Schmalkalden, Germany. To determine the key factors which benefited the development of this collapse structure and therefore the dissolution, we carried out several shear-wave reflection-seismic profiles around the sinkhole. In the seismic sections we see evidence of the Mesozoic tectonic movement in the form of a NW–SE striking, dextral strike-slip fault, known as the Heßleser Fault, which faulted and fractured the subsurface below the town. The strike-slip faulting created a zone of small blocks ( < 100 m in size, around which steep-dipping normal faults, reverse faults and a dense fracture network serve as fluid pathways for the artesian-confined groundwater. The faults also acted as barriers for horizontal groundwater flow perpendicular to the fault planes. Instead groundwater flows along the faults which serve as conduits and forms cavities in the Permian deposits below ca. 60 m depth. Mass movements and the resulting cavities lead to the formation of sinkholes and dissolution-induced depressions. Since the processes are still ongoing, the occurrence of a new sinkhole cannot be ruled out. This case study demonstrates how S-wave seismics can characterize a sinkhole and, together with geological information, can be used to study the processes that result in sinkhole formation, such as a near-surface fault zone located in soluble rocks. The more complex the fault geometry and interaction between faults, the more prone an area is to sinkhole occurrence.

  20. (Plio-)Pleistocene alluvial-lacustrine basin infill evolution in a strike-slip active zone (Northern Andes, Western-Central Cordilleras, Colombia)

    OpenAIRE

    SUTER, F.; NEUWERTH, R.; GORIN, G.; GUZMÁN, C.

    2009-01-01

    The (Plio)-Pleistocene Zarzal Formation was deposited in the Cauca Depression and Quindío-Risaralda Basin between the Western and Central Cordilleras (Northern Andes). This area is structurally located on the transcurrent Romeral Fault System (RFS). Because of the interaction between the Nazca plate and the Chocó-Panamá block (an active indenter), the RFS strike-slip component changes direction around the study zone (dextral in the south, senestral in the north). Zarzal sediments are the olde...

  1. The San Andreas Fault and a Strike-slip Fault on Europa

    Science.gov (United States)

    1998-01-01

    The mosaic on the right of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, the size of the California portion of the San Andreas fault on Earth which runs from the California-Mexico border north to the San Francisco Bay. The left mosaic shows the portion of the San Andreas fault near California's san Francisco Bay that has been scaled to the same size and resolution as the Europa image. Each covers an area approximately 170 by 193 kilometers(105 by 120 miles). The red line marks the once active central crack of the Europan fault (right) and the line of the San Andreas fault (left). A strike-slip fault is one in which two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. The overall motion along the Europan fault seems to have followed a continuous narrow crack along the entire length of the feature, with a path resembling stepson a staircase crossing zones which have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. Opposite sides of the fault can be reconstructed like a puzzle, matching the shape of the sides as well as older individual cracks and ridges that had been broken by its movements. Bends in the Europan fault have allowed the surface to be pulled apart. This pulling-apart along the fault's bends created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, and in Death Valley and the Dead Sea. In those cases, the pulled apart regions can include upwelled materials, but may

  2. Effects of embedment including slip and separation on seismic SSI response of a nuclear reactor building

    International Nuclear Information System (INIS)

    Saxena, Navjeev; Paul, D.K.

    2012-01-01

    Highlights: ► Both the slip and separation of reactor base reduce with increase in embedment. ► The slip and separation become insignificant beyond 1/4 and 1/2 embedment respectively. ► The stresses in reactor reduce significantly upto 1/4 embedment. ► The stress reduction with embedment is more pronounced in case of tensile stresses. ► The modeling of interface is important beyond 1/8 embedment as stresses are underestimated otherwise. - Abstract: The seismic response of nuclear reactor containment building considering the effects of embedment, slip and separation at soil–structure interface requires modeling of the soil, structure and interface altogether. Slip and separation at the interface causes stress redistribution in the soil and the structure around the interface. The embedment changes the dynamic characteristics of the soil–structure system. Consideration of these aspects allows capturing the realistic response of the structure, which has been a research gap and presented here individually as well as taken together. Finite element analysis has been carried out in time domain to attempt the highly nonlinear problem. The study draws important conclusions useful for design of nuclear reactor containment building.

  3. 'Extra-regional' strike-slip fault systems in Chile and Alaska: the North Pacific Rim orogenic Stream vs. Beck's Buttress

    Science.gov (United States)

    Redfield, T. F.; Scholl, D. W.; Fitzgerald, P. G.

    2010-12-01

    The ~2000 km long Denali Fault System (DFS) of Alaska is an example of an extra-regional strike-slip fault system that terminates in a zone of widely-distributed deformation. The ~1200 km long Liquiñe-Ofqui Fault Zone (LOFZ) of Patagonia (southern Chile) is another. Both systems are active, having undergone large-magnitude seismic rupture is 2002 (DFS) and 2007 (LOFZ). Both systems appear to be long-lived: the DFS juxtaposes terranes that docked in at least early Tertiary time, whilst the central LOFZ appears to also record early Tertiary or Mesozoic deformation. Both fault systems comprise a relatively well-defined central zone where individual fault traces can be identified from topographic features or zones of deformed rock. In both cases the proximal and distal traces are much more diffuse tributary and distributary systems of individual, branching fault traces. However, since their inception the DFS and LOFZ have followed very different evolutionary paths. Copious Alaskan paleomagnetic data are consistent with vertical axis small block rotation, long-distance latitudinal translation, and a recently-postulated tectonic extrusion towards a distributary of subordinate faults that branch outward towards the Aleution subduction zone (the North Pacific Rim orogenic Stream; see Redfield et al., 2007). Paleomagnetic data from the LOFZ region are consistent with small block rotation but preclude statistically-significant latitudinal transport. Limited field data from the southernmost LOFZ suggest that high-angle normal and reverse faults dominate over oblique to strike-slip structures. Rather than the high-angle oblique 'slivering regime' of the southeasternmost DFS, the initiation of the LOFZ appears to occur across a 50 to 100 km wide zone of brittly-deformed granitic and gneissic rock characterized by bulk compression and vertical pathways of exhumation. In both cases, relative plate motions are consistent with the hypothetical style, and degree, of offset, leading

  4. Timing of metamorphism of the Lansang gneiss and implications for left-lateral motion along the Mae Ping (Wang Chao) strike-slip fault, Thailand

    Science.gov (United States)

    Palin, R. M.; Searle, M. P.; Morley, C. K.; Charusiri, P.; Horstwood, M. S. A.; Roberts, N. M. W.

    2013-10-01

    The Mae Ping fault (MPF), western Thailand, exhibits dominantly left-lateral strike-slip motion and stretches for >600 km, reportedly branching off the right-lateral Sagaing fault in Myanmar and extending southeast towards Cambodia. Previous studies have suggested that the fault assisted the large-scale extrusion of Sundaland that occurred during the Late Eocene-Early Oligocene, with a geological offset of ˜120-150 km estimated from displaced high-grade gneisses and granites of the Chiang Mai-Lincang belt. Exposures of high-grade orthogneiss in the Lansang National Park, part of this belt, locally contain strong mylonitic textures and are bounded by strike-slip ductile shear zones and brittle faults. Geochronological analysis of monazite from a sample of sheared biotite-K-feldspar orthogneiss suggests two episodes of crystallization, with core regions documenting Th-Pb ages between c. 123 and c. 114 Ma and rim regions documenting a significantly younger age range between c. 45-37 Ma. These data are interpreted to represent possible magmatic protolith emplacement for the Lansang orthogneiss during the Early Cretaceous, with a later episode of metamorphism occurring during the Eocene. Textural relationships provided by in situ analysis suggest that ductile shearing along the MPF occurred during the latter stages of, or after, this metamorphic event. In addition, monazite analyzed from an undeformed garnet-two-mica granite dyke intruding metamorphic units at Bhumipol Lake outside of the Mae Ping shear zone produced a Th-Pb age of 66.2 ± 1.6 Ma. This age is interpreted to date the timing of dyke emplacement, implying that the MPF cuts through earlier formed magmatic and high-grade metamorphic rocks. These new data, when combined with regional mapping and earlier geochronological work, show that neither metamorphism, nor regional cooling, was directly related to strike-slip motion.

  5. 3D deformation in strike-slip systems: Analogue modelling and numerical restoration Deformación 3D en sistemas de rumbo: modelación analógica y restauración numérica

    Directory of Open Access Journals (Sweden)

    Daniel González

    2012-05-01

    Full Text Available Regional and local strike-slip systems in Chile are complex and pose interesting questions, such as the interaction between strike-slip and reverse faults, how they evolve, and the relationship between shortening, rotation and uplift. Within this context, we developed a new analytical method based on analogue and numerical modelling applied to 3D, pure and transtensional-transpressional strike-slip systems. Analogue modelling results indicate that in restraining stepovers of strike-slip fault systems, where antiformal pop-up structures are usually formed, pre-existent basement structures with a high angle to the main strike-slip fault will generate a higher rotation of blocks. However, when these structures are oriented at a high angle with respect to the main stress convergence vector, the rotation will be less and therefore a higher tendency to uplift will be produced. These results were applied to NW- and SE-striking basement faults oblique to N-S mega-thrust faults in central Chile (32°-35°S, for which we propose a simultaneous development based on the analogue model results. Moreover, we propose that strike-slip movement occurred on thrust faults in central Chile. Furthermore, we performed a numerical restoration of an analogue experiment which modeled a pure strike-slip system, and concluded that the restoration is very sensitive to shortening data as well as to rotational data. These results are extremely important for future numerical and regional analysis of strike-slip systems.Los sistemas de rumbo regionales y locales en Chile son complejos y plantean interesantes preguntas, tales como la interacción entre fallas de rumbo y fallas inversas, cómo evolucionan ellas, y la relación entre acortamiento, rotación y alzamiento. En este contexto, desarrollamos un nuevo método analítico basado en modelamiento analógico y numérico de sistemas de rumbo de cizalle puro y sistemas transpresionales-trantensionales en 3D. Los resultados del

  6. A Physical Analog Model of Strike-Slip Faulting for Model-Based Inquiry in the Classroom

    Science.gov (United States)

    Curren, I. S.; Glesener, G.

    2013-12-01

    Geoscience educators often use qualitative physical analog models to demonstrate natural processes; while these are effective teaching tools, they often neglect the fundamental scientific practices that make up the core of scientific work. Physical analog models with dynamic properties that can be manipulated and measured quantitatively in real-time, on the other hand, can give students the opportunity to explore, observe and empirically test their own ideas and hypotheses about the relevant target concepts within a classroom setting. Providing classroom content for inquiry, such as a hands-on physical analog model, which fosters students' production and refinement of their mental models in participatory and discursive activities have been argued by many education researchers to help students build a deeper understanding of science and scientific reasoning. We present a physical analog model that was originally developed by UCLA's Modeling and Educational Demonstrations Laboratory (MEDL) for the purpose of engaging students in the study of elastic rebound on a strike-slip fault; it was later modified to accommodate research of complex tectonic processes associated with strike-slip faulting, which are currently debated by scientists in both the geology and geophysics disciplines. During experimentation, it became clear that this new design could be used as a relevant resource for inquiry from which students would be able to make and discuss real-time empirical measurements and observations to help them infer causal accounts of theoretical and/or unobservable dynamic processes within the Earth's crust. In our poster session, we will: 1) demonstrate the physical analog model; 2) describe various real-time data collection tools, as well as quantitative methods students can use to process their data; and 3) describe the surficial, structural and relational similarities between the physical analog model and the target concepts intended for students to explore in the

  7. Earthquake scaling laws for rupture geometry and slip heterogeneity

    Science.gov (United States)

    Thingbaijam, Kiran K. S.; Mai, P. Martin; Goda, Katsuichiro

    2016-04-01

    We analyze an extensive compilation of finite-fault rupture models to investigate earthquake scaling of source geometry and slip heterogeneity to derive new relationships for seismic and tsunami hazard assessment. Our dataset comprises 158 earthquakes with a total of 316 rupture models selected from the SRCMOD database (http://equake-rc.info/srcmod). We find that fault-length does not saturate with earthquake magnitude, while fault-width reveals inhibited growth due to the finite seismogenic thickness. For strike-slip earthquakes, fault-length grows more rapidly with increasing magnitude compared to events of other faulting types. Interestingly, our derived relationship falls between the L-model and W-model end-members. In contrast, both reverse and normal dip-slip events are more consistent with self-similar scaling of fault-length. However, fault-width scaling relationships for large strike-slip and normal dip-slip events, occurring on steeply dipping faults (δ~90° for strike-slip faults, and δ~60° for normal faults), deviate from self-similarity. Although reverse dip-slip events in general show self-similar scaling, the restricted growth of down-dip fault extent (with upper limit of ~200 km) can be seen for mega-thrust subduction events (M~9.0). Despite this fact, for a given earthquake magnitude, subduction reverse dip-slip events occupy relatively larger rupture area, compared to shallow crustal events. In addition, we characterize slip heterogeneity in terms of its probability distribution and spatial correlation structure to develop a complete stochastic random-field characterization of earthquake slip. We find that truncated exponential law best describes the probability distribution of slip, with observable scale parameters determined by the average and maximum slip. Applying Box-Cox transformation to slip distributions (to create quasi-normal distributed data) supports cube-root transformation, which also implies distinctive non-Gaussian slip

  8. The initiation and linkage of surface fractures above a buried strike ...

    Indian Academy of Sciences (India)

    a buried strike-slip fault: An experimental approach. N Ghosh and A ... conditions viz., (i) heterogeneous simple shear of the cover rocks above a buried strike slip fault. (wrench .... (iii) study of fracture types in the damage zones from Gozo .... was dominant, the results may vary from a true ... For example, as shown in figure 5 ...

  9. Influence of fault steps on rupture termination of strike-slip earthquake faults

    Science.gov (United States)

    Li, Zhengfang; Zhou, Bengang

    2018-03-01

    A statistical analysis was completed on the rupture data of 29 historical strike-slip earthquakes across the world. The purpose of this study is to examine the effects of fault steps on the rupture termination of these events. The results show good correlations between the type and length of steps with the seismic rupture and a poor correlation between the step number and seismic rupture. For different magnitude intervals, the smallest widths of the fault steps (Lt) that can terminate the rupture propagation are variable: Lt = 3 km for Ms 6.5 6.9, Lt = 4 km for Ms 7.0 7.5, Lt = 6 km for Ms 7.5 8.0, and Lt = 8 km for Ms 8.0 8.5. The dilational fault step is easier to rupture through than the compression fault step. The smallest widths of the fault step for the rupture arrest can be used as an indicator to judge the scale of the rupture termination of seismic faults. This is helpful for research on fault segmentation, as well as estimating the magnitude of potential earthquakes, and is thus of significance for the assessment of seismic risks.

  10. Constraining slip rates and spacings for active normal faults

    Science.gov (United States)

    Cowie, Patience A.; Roberts, Gerald P.

    2001-12-01

    Numerous observations of extensional provinces indicate that neighbouring faults commonly slip at different rates and, moreover, may be active over different time intervals. These published observations include variations in slip rate measured along-strike of a fault array or fault zone, as well as significant across-strike differences in the timing and rates of movement on faults that have a similar orientation with respect to the regional stress field. Here we review published examples from the western USA, the North Sea, and central Greece, and present new data from the Italian Apennines that support the idea that such variations are systematic and thus to some extent predictable. The basis for the prediction is that: (1) the way in which a fault grows is fundamentally controlled by the ratio of maximum displacement to length, and (2) the regional strain rate must remain approximately constant through time. We show how data on fault lengths and displacements can be used to model the observed patterns of long-term slip rate where measured values are sparse. Specifically, we estimate the magnitude of spatial variation in slip rate along-strike and relate it to the across-strike spacing between active faults.

  11. Silurian to Devonian magmatism, molybdenite mineralization, regional exhumation and brittle strike-slip deformation along the Loch Shin Line, NW Scotland

    OpenAIRE

    Holdsworth, R.; Dempsey, E.; Selby, D.; Darling, James Richard; Feely, M.; Costanzo, A.; Strachan, Robin A; Waters, P.; Finlay, A.J.

    2015-01-01

    The Loch Shin Line is a geological–geophysical lineament associated with a zone of mantle-derived appinites, granites and strike-slip faulting that runs NW–SE across the Moine Nappe, northern Scotland. U–Pb zircon and Re–Os molybdenite dating of the Loch Shin and Grudie plutons, which lie immediately SW of the NW–SE Loch Shin–Strath Fleet fault system, yield c. 427–430 Ma ages that overlap within error. They also coincide with previously obtained U–Pb zircon ages for the Rogart pluton, which ...

  12. A nonlinear least-squares inverse analysis of strike-slip faulting with application to the San Andreas fault

    Science.gov (United States)

    Williams, Charles A.; Richardson, Randall M.

    1988-01-01

    A nonlinear weighted least-squares analysis was performed for a synthetic elastic layer over a viscoelastic half-space model of strike-slip faulting. Also, an inversion of strain rate data was attempted for the locked portions of the San Andreas fault in California. Based on an eigenvector analysis of synthetic data, it is found that the only parameter which can be resolved is the average shear modulus of the elastic layer and viscoelastic half-space. The other parameters were obtained by performing a suite of inversions for the fault. The inversions on data from the northern San Andreas resulted in predicted parameter ranges similar to those produced by inversions on data from the whole fault.

  13. Near N-S paleo-extension in the western Deccan region, India: Does it link strike-slip tectonics with India-Seychelles rifting?

    Science.gov (United States)

    Misra, Achyuta Ayan; Bhattacharya, Gourab; Mukherjee, Soumyajit; Bose, Narayan

    2014-09-01

    This is the first detailed report and analyses of deformation from the W part of the Deccan large igneous province (DLIP), Maharashtra, India. This deformation, related to the India-Seychelles rifting during Late Cretaceous-Early Paleocene, was studied, and the paleostress tensors were deduced. Near N-S trending shear zones, lineaments, and faults were already reported without significant detail. An E-W extension was envisaged by the previous workers to explain the India-Seychelles rift at ~64 Ma. The direction of extension, however, does not match with their N-S brittle shear zones and also those faults (sub-vertical, ~NE-SW/~NW-SE, and few ~N-S) we report and emphasize in this work. Slickenside-bearing fault planes, brittle shear zones, and extension fractures in meso-scale enabled us to estimate the paleostress tensors (directions and relative magnitudes). The field study was complemented by remote sensing lineament analyses to map dykes and shear zones. Dykes emplaced along pre-existing ~N-S to ~NE-SW/~NW-SE shears/fractures. This information was used to derive regional paleostress trends. A ~NW-SE/NE-SW minimum compressive stress in the oldest Kalsubai Subgroup and a ~N-S direction for the younger Lonavala, Wai, and Salsette Subgroups were deciphered. Thus, a ~NW/NE to ~N-S extension is put forward that refutes the popular view of E-W India-Seychelles extension. Paleostress analyses indicate that this is an oblique rifted margin. Field criteria suggest only ~NE-SW and ~NW-SE, with some ~N-S strike-slip faults/brittle shear zones. We refer this deformation zone as the "Western Deccan Strike-slip Zone" (WDSZ). The observed deformation was matched with offshore tectonics deciphered mainly from faults interpreted on seismic profiles and from magnetic seafloor spreading anomalies. These geophysical findings too indicate oblique rifting in this part of the W Indian passive margin. We argue that the Seychelles microcontinent separated from India only after much of

  14. Fault Slip Partitioning in the Eastern California Shear Zone-Walker Lane Belt: Pliocene to Late Pleistocene Contraction Across the Mina Deflection

    Science.gov (United States)

    Lee, J.; Stockli, D.; Gosse, J.

    2007-12-01

    Two different mechanisms have been proposed for fault slip transfer between the subparallel NW-striking dextral- slip faults that dominant the Eastern California Shear Zone (ECSZ)-Walker Lane Belt (WLB). In the northern WLB, domains of sinistral-slip along NE-striking faults and clockwise block rotation within a zone of distributed deformation accommodated NW-dextral shear. A somewhat modified version of this mechanism was also proposed for the Mina deflection, southern WLB, whereby NE-striking sinistral faults formed as conjugate faults to the primary zone of NW-dextral shear; clockwise rotation of the blocks bounding the sinistral faults accommodated dextral slip. In contrast, in the northern ECSZ and Mina deflection, domains of NE-striking pure dip-slip normal faults, bounded by NW-striking dextral-slip faults, exhibited no rotation; the proposed mechanism of slip transfer was one of right-stepping, high angle normal faults in which the magnitude of extension was proportional to the amount of strike-slip motion transferred. New geologic mapping, tectonic geomorphologic, and geochronologic data from the Queen Valley area, southern Mina deflection constrain Pliocene to late Quaternary fault geometries, slip orientations, slip magnitudes, and slip rates that bear on the mechanism of fault slip transfer from the relatively narrow northern ECSZ to the broad deformation zone that defines the Mina deflection. Four different fault types and orientations cut across the Queen Valley area: (1) The NE-striking normal-slip Queen Valley fault; (2) NE-striking sinistral faults; (3) the NW-striking dextral Coyote Springs fault, which merges into (4) a set of EW-striking thrust faults. (U-Th)/He apatite and cosmogenic radionuclide data, combined with magnitude of fault offset measurements, indicate a Pliocene to late Pleistocene horizontal extension rate of 0.2-0.3 mm/yr across the Queen Valley fault. Our results, combined with published slip rates for the dextral White Mountain

  15. A recent Mw 4.3 earthquake proving activity of a shallow strike-slip fault in the northern part of the Western Desert, Egypt

    Science.gov (United States)

    Ezzelarab, Mohamed; Ebraheem, Mohamed O.; Zahradník, Jiří

    2018-03-01

    The Mw 4.3 earthquake of September 2015 is the first felt earthquake since 1900 A.D in the northern part of the Western Desert, Egypt, south of the El-Alamein City. The available waveform data observed at epicentral distances 52-391 km was collected and carefully evaluated. Nine broad-band stations were selected to invert full waveforms for the centroid position (horizontal and vertical) and for the focal mechanism solution. The first-arrival travel times, polarities and low-frequency full waveforms (0.03-0.08 Hz) are consistently explained in this paper as caused by a shallow source of the strike-slip mechanism. This finding indicates causal relation of this earthquake to the W-E trending South El-Alamein fault, which developed in Late Cretaceous as dextral strike slip fault. Recent activity of this fault, proven by the studied rare earthquake, is of fundamental importance for future seismic hazard evaluations, underlined by proximity (∼65 km) of the source zone to the first nuclear power plant planned site in Egypt. Safe exploration and possible future exploitation of hydrocarbon reserves, reported around El-Alamein fault in the last decade, cannot be made without considering the seismic potential of this fault.

  16. Fault slip and earthquake recurrence along strike-slip faults — Contributions of high-resolution geomorphic data

    KAUST Repository

    Zielke, Olaf

    2015-01-01

    Understanding earthquake (EQ) recurrence relies on information about the timing and size of past EQ ruptures along a given fault. Knowledge of a fault\\'s rupture history provides valuable information on its potential future behavior, enabling seismic hazard estimates and loss mitigation. Stratigraphic and geomorphic evidence of faulting is used to constrain the recurrence of surface rupturing EQs. Analysis of the latter data sets culminated during the mid-1980s in the formulation of now classical EQ recurrence models, now routinely used to assess seismic hazard. Within the last decade, Light Detection and Ranging (lidar) surveying technology and other high-resolution data sets became increasingly available to tectono-geomorphic studies, promising to contribute to better-informed models of EQ recurrence and slip-accumulation patterns. After reviewing motivation and background, we outline requirements to successfully reconstruct a fault\\'s offset accumulation pattern from geomorphic evidence. We address sources of uncertainty affecting offset measurement and advocate approaches to minimize them. A number of recent studies focus on single-EQ slip distributions and along-fault slip accumulation patterns. We put them in context with paleoseismic studies along the respective faults by comparing coefficients of variation CV for EQ inter-event time and slip-per-event and find that a) single-event offsets vary over a wide range of length-scales and the sources for offset variability differ with length-scale, b) at fault-segment length-scales, single-event offsets are essentially constant, c) along-fault offset accumulation as resolved in the geomorphic record is dominated by essentially same-size, large offset increments, and d) there is generally no one-to-one correlation between the offset accumulation pattern constrained in the geomorphic record and EQ occurrence as identified in the stratigraphic record, revealing the higher resolution and preservation potential of

  17. Insights on the seismotectonics of the western part of northern Calabria (southern Italy) by integrated geological and geophysical data: Coexistence of shallow extensional and deep strike-slip kinematics

    Science.gov (United States)

    Ferranti, L.; Milano, G.; Pierro, M.

    2017-11-01

    We assess the seismotectonics of the western part of the border area between the Southern Apennines and Calabrian Arc, centered on the Mercure extensional basin, by integrating recent seismicity with a reconstruction of the structural frame from surface to deep crust. The analysis of low-magnitude (ML ≤ 3.5) events occurred in the area during 2013-2017, when evaluated in the context of the structural model, has revealed an unexpected complexity of seismotectonics processes. Hypocentral distribution and kinematics allow separating these events into three groups. Focal mechanisms of the shallower (kinematics. These results are consistent with the last kinematic event recorded on outcropping faults, and with the typical depth and kinematics of normal faulting earthquakes in the axial part of southern Italy. By contrast, intermediate ( 9-17 km) and deep ( 17-23 km) events have fault plane solutions characterized by strike- to reverse-oblique slip, but they differ from each other in the orientation of the principal axes. The intermediate events have P axes with a NE-SW trend, which is at odds with the NW-SE trend recorded by strike-slip earthquakes affecting the Apulia foreland plate in the eastern part of southern Italy. The intermediate events are interpreted to reflect reactivation of faults in the Apulia unit involved in thrust uplift, and appears aligned along an WNW-ESE trending deep crustal, possibly lithospheric boundary. Instead, deep events beneath the basin, which have P-axis with a NW-SE trend, hint to the activity of a deep overthrust of the Tyrrhenian back-arc basin crust over the continental crust of the Apulia margin, or alternatively, to a tear fault in the underthrust Apulia plate. Results of this work suggest that extensional faulting, as believed so far, does not solely characterizes the seismotectonics of the axial part of the Southern Apennines.

  18. Palaeopermeability anisotropies of a strike-slip fault damage zone: 3D Insights of quantitative fluid flow from µCT analysis.

    Science.gov (United States)

    Gomila, R.; Arancibia, G.; Nehler, M.; Bracke, R.; Morata, D.

    2017-12-01

    Fault zones and their related structural permeability are a key aspect in the migration of fluids through the continental crust. Therefore, the estimation of the hydraulic properties (palaeopermeability conditions; k) and the spatial distribution of the fracture mesh within the damage zone (DZ) are critical in the assessment of fault zones behavior for fluids. The study of the real spatial distribution of the veinlets of the fracture mesh (3D), feasible with the use of µCT analyses, is a first order factor to unravel both, the real structural permeability conditions of a fault-zone, and the validation of previous (and classical) estimations made in 2D analyses in thin-sections. This work shows the results of a fault-related fracture mesh and its 3D spatial distribution in the damage-zone of the Jorgillo Fault (JF), an ancient subvertical left-lateral strike-slip fault exposed in the Atacama Fault System in northern Chile. The JF is a ca. 20 km long NNW-striking strike-slip fault with sinistral displacement of ca. 4 km. The methodology consisted of drilling 5 mm vertically oriented plugs at several locations within the JF damage zone. Each specimen was scanned with an X-Ray µCT scanner, to assess the fracture mesh, with a voxel resolution of ca. 4.5 µm in the 3D reconstructed data. Tensor permeability modeling, using Lattice-Boltzmann Method, through the segmented microfracture mesh show GMkmin (geometric mean values) of 2.1x10-12 and 9.8x10-13 m2, and GMkmax of 6.4x10-12 and 2.1x10-12 m2. A high degree of anisotropy of the DZ permeability tensor both sides of the JF (eastern and western side, respectively) is observed, where the k values in the kmax plane are 2.4 and 1.9 times higher than the kmin direction at the time of fracture sealing. This style of anisotropy is consistent with the obtained for bedded sandstones supporting the idea that damage zones have an analogous effect - but vertically orientated - on bulk permeability (in low porosity rocks) as

  19. Spatial and Temporal Variations in Slip Partitioning During Oblique Convergence Experiments

    Science.gov (United States)

    Beyer, J. L.; Cooke, M. L.; Toeneboehn, K.

    2017-12-01

    Physical experiments of oblique convergence in wet kaolin demonstrate the development of slip partitioning, where two faults accommodate strain via different slip vectors. In these experiments, the second fault forms after the development of the first fault. As one strain component is relieved by one fault, the local stress field then favors the development of a second fault with different slip sense. A suite of physical experiments reveals three styles of slip partitioning development controlled by the convergence angle and presence of a pre-existing fault. In experiments with low convergence angles, strike-slip faults grow prior to reverse faults (Type 1) regardless of whether the fault is precut or not. In experiments with moderate convergence angles, slip partitioning is dominantly controlled by the presence of a pre-existing fault. In all experiments, the primarily reverse fault forms first. Slip partitioning then develops with the initiation of strike-slip along the precut fault (Type 2) or growth of a secondary reverse fault where the first fault is steepest. Subsequently, the slip on the first fault transitions to primarily strike-slip (Type 3). Slip rates and rakes along the slip partitioned faults for both precut and uncut experiments vary temporally, suggesting that faults in these slip-partitioned systems are constantly adapting to the conditions produced by slip along nearby faults in the system. While physical experiments show the evolution of slip partitioning, numerical simulations of the experiments provide information about both the stress and strain fields, which can be used to compute the full work budget, providing insight into the mechanisms that drive slip partitioning. Preliminary simulations of precut experiments show that strain energy density (internal work) can be used to predict fault growth, highlighting where fault growth can reduce off-fault deformation in the physical experiments. In numerical simulations of uncut experiments with a

  20. Documentation of programs that compute 1) static tilts for a spatially variable slip distribution, and 2) quasi-static tilts produced by an expanding dislocation loop with a spatially variable slip distribution

    Science.gov (United States)

    McHugh, Stuart

    1976-01-01

    The material in this report is concerned with the effects of a vertically oriented rectangular dislocation loop on the tilts observed at the free surface of an elastic half-space. Part I examines the effect of a spatially variable static strike-slip distribution across the slip surface. The tilt components as a function of distance parallel, or perpendicular, to the strike of the slip surface are displayed for different slip-versus-distance profiles. Part II examines the effect of spatially and temporally variable slip distributions across the dislocation loop on the quasi-static tilts at the free surface of an elastic half space. The model discussed in part II may be used to generate theoretical tilt versus time curves produced by creep events.

  1. Seismic and geodetic signatures of fault slip at the Slumgullion Landslide Natural Laboratory

    Science.gov (United States)

    Gomberg, J.; Schulz, W.; Bodin, P.; Kean, J.

    2011-01-01

    We tested the hypothesis that the Slumgullion landslide is a useful natural laboratory for observing fault slip, specifically that slip along its basal surface and side-bounding strike-slip faults occurs with comparable richness of aseismic and seismic modes as along crustal- and plate-scale boundaries. Our study provides new constraints on models governing landslide motion. We monitored landslide deformation with temporary deployments of a 29-element prism array surveyed by a robotic theodolite and an 88-station seismic network that complemented permanent extensometers and environmental instrumentation. Aseismic deformation observations show that large blocks of the landslide move steadily at approximately centimeters per day, possibly punctuated by variations of a few millimeters, while localized transient slip episodes of blocks less than a few tens of meters across occur frequently. We recorded a rich variety of seismic signals, nearly all of which originated outside the monitoring network boundaries or from the side-bounding strike-slip faults. The landslide basal surface beneath our seismic network likely slipped almost completely aseismically. Our results provide independent corroboration of previous inferences that dilatant strengthening along sections of the side-bounding strike-slip faults controls the overall landslide motion, acting as seismically radiating brakes that limit acceleration of the aseismically slipping basal surface. Dilatant strengthening has also been invoked in recent models of transient slip and tremor sources along crustal- and plate-scale faults suggesting that the landslide may indeed be a useful natural laboratory for testing predictions of specific mechanisms that control fault slip at all scales.

  2. Fault Branching and Long-Term Earthquake Rupture Scenario for Strike-Slip Earthquake

    Science.gov (United States)

    Klinger, Y.; CHOI, J. H.; Vallage, A.

    2017-12-01

    Careful examination of surface rupture for large continental strike-slip earthquakes reveals that for the majority of earthquakes, at least one major branch is involved in the rupture pattern. Often, branching might be either related to the location of the epicenter or located toward the end of the rupture, and possibly related to the stopping of the rupture. In this work, we examine large continental earthquakes that show significant branches at different scales and for which ground surface rupture has been mapped in great details. In each case, rupture conditions are described, including dynamic parameters, past earthquakes history, and regional stress orientation, to see if the dynamic stress field would a priori favor branching. In one case we show that rupture propagation and branching are directly impacted by preexisting geological structures. These structures serve as pathways for the rupture attempting to propagate out of its shear plane. At larger scale, we show that in some cases, rupturing a branch might be systematic, hampering possibilities for the development of a larger seismic rupture. Long-term geomorphology hints at the existence of a strong asperity in the zone where the rupture branched off the main fault. There, no evidence of throughgoing rupture could be seen along the main fault, while the branch is well connected to the main fault. This set of observations suggests that for specific configurations, some rupture scenarios involving systematic branching are more likely than others.

  3. Fault slip and earthquake recurrence along strike-slip faults — Contributions of high-resolution geomorphic data

    KAUST Repository

    Zielke, Olaf; Klinger, Yann; Arrowsmith, J. Ramon

    2015-01-01

    to contribute to better-informed models of EQ recurrence and slip-accumulation patterns. After reviewing motivation and background, we outline requirements to successfully reconstruct a fault's offset accumulation pattern from geomorphic evidence. We address

  4. Inefficient postural responses to unexpected slips during walking in older adults.

    Science.gov (United States)

    Tang, P F; Woollacott, M H

    1998-11-01

    Slips account for a high percentage of falls and subsequent injuries in community-dwelling older adults but not in young adults. This phenomenon suggests that although active and healthy older adults preserve a mobility level comparable to that of young adults, these older adults may have difficulty generating efficient reactive postural responses when they slip. This study tested the hypothesis that active and healthy older adults use a less effective reactive balance strategy than young adults when experiencing an unexpected forward slip occurring at heel strike during walking. This less effective balance strategy would be manifested by slower and smaller postural responses, altered temporal and spatial organization of the postural responses, and greater upper trunk instability after the slip. Thirty-three young adults (age range=19-34 yrs, mean=25+/-4 yrs) and 32 community-dwelling older adults (age range=70-87 yrs, mean=74+/-14 yrs) participated. Subjects walked across a movable forceplate which simulated a forward slip at heel strike. Surface electromyography was recorded from bilateral leg, thigh, hip, and trunk muscles. Kinematic data were collected from the right (perturbed) side of the body. Although the predominant postural muscles and the activation sequence of these muscles were similar between the two age groups, the postural responses of older adults were of longer onset latencies, smaller magnitudes, and longer burst durations compared to young adults. Older adults also showed a longer coactivation duration for the ankle, knee, and trunk agonist/antagonist pairs on the perturbed side and for the knee agonist/antagonist pair on the nonperturbed side. Behaviorally, older adults became less stable after the slips. This was manifested by a higher incidence of being tripped (21 trials in older vs 5 trials in young adults) and a greater trunk hyperextension with respect to young adults. Large arm elevation was frequently used by older adults to assist in

  5. The Implications of Strike-Slip Earthquake Source Properties on the Transform Boundary Development Process

    Science.gov (United States)

    Neely, J. S.; Huang, Y.; Furlong, K.

    2017-12-01

    Subduction-Transform Edge Propagator (STEP) faults, produced by the tearing of a subducting plate, allow us to study the development of a transform plate boundary and improve our understanding of both long-term geologic processes and short-term seismic hazards. The 280 km long San Cristobal Trough (SCT), formed by the tearing of the Australia plate as it subducts under the Pacific plate near the Solomon and Vanuatu subduction zones, shows along-strike variations in earthquake behaviors. The segment of the SCT closest to the tear rarely hosts earthquakes > Mw 6, whereas the SCT sections more than 80 - 100 km from the tear experience Mw7 earthquakes with repeated rupture along the same segments. To understand the effect of cumulative displacement on SCT seismicity, we analyze b-values, centroid-time delays and corner frequencies of the SCT earthquakes. We use the spectral ratio method based on Empirical Green's Functions (eGfs) to isolate source effects from propagation and site effects. We find high b-values along the SCT closest to the tear with values decreasing with distance before finally increasing again towards the far end of the SCT. Centroid time-delays for the Mw 7 strike-slip earthquakes increase with distance from the tear, but corner frequency estimates for a recent sequence of Mw 7 earthquakes are approximately equal, indicating a growing complexity in earthquake behavior with distance from the tear due to a displacement-driven transform boundary development process (see figure). The increasing complexity possibly stems from the earthquakes along the eastern SCT rupturing through multiple asperities resulting in multiple moment pulses. If not for the bounding Vanuatu subduction zone at the far end of the SCT, the eastern SCT section, which has experienced the most displacement, might be capable of hosting larger earthquakes. When assessing the seismic hazard of other STEP faults, cumulative fault displacement should be considered a key input in

  6. COMPARISON OF COSEISMIC IONOSPHERIC DISTURBANCE WAVEFORMS REVISITED: STRIKE-SLIP, NORMAL, AND REVERSE FAULT EARTHQUAKE

    Directory of Open Access Journals (Sweden)

    Mokhamad Nur Cahyadi

    2015-02-01

    Full Text Available Using Total Electron Content (TEC measurements with Global Positioning System we studied ionospheric responses to three large earthquakes with difference focal mechanism that occurred in the Sumatra Andaman 26 December 2004, North off Sumatra 11 April 2012, and North Japan 7 December 2012. These earthquakes have different focal mechanisms, i.e. high-angle reverse, strike-slip, and normal faulting, respectively. TEC responses to the Sumatra Andaman 2004 and north Japan 2012 events initiated with positive changes. On the other hand, the initial TEC changes in the Sumatra 2012 earthquake showed both positive and negative polarities depending on the azimuth around the focal area. Such a variety may reflect differences in coseismic vertical crustal displacements, which are dominated by uplift and subsidence in the Sumatra 2012 event. This phenomena has same characteristic with 1994 Kuril Arch earthquake. There are three different propagation velocity in the Sumatra 2012 earthquake, within the first 300 km until 430 km, the CID propagation velocity was ~3 km/s, which is equal to the secod sound speed at the height of the ionospheric F-layer. Starting from 380 km until 750 km out from the epicenter, the disturbance seems to divide into two separate perturbations, with each propagating at a different velocity, about 1 km/s for the one and about 0.4 m/s for the other. The apparent velocity in the Sumatra Andaman 2004 and Japan 2012 propagated ~ 1 km/s and ~ 0.3 km/s, consistent with the sound speed at the ionospheric F layer height and internal gravity wave respectively. Resonant oscillation of TEC with a frequency of ~ 3.7 mHZ and ~4.4 mHz have been found in the Sumatra 2012 and Sumatra Andaman 2004 events. Those earthquakes, which occurred during a period of quiet geomagnetic activity, also showed clear preseismic TEC anomalies similar to those before the 2011 Tohoku-Oki and 2007 Bengkulu earthquake.   The positive anomalies started 30-60 minutes

  7. Preliminary slip history of the 2002 Denali earthquake

    Science.gov (United States)

    Ji, C.; Helmberger, D.; Wald, D.

    2002-12-01

    Rapid slip histories for the 2002 Denali earthquake were derived from the IRIS global data before geologists arrived in the field. We were able to predict many of the features they observed. Three models were produced indicating a step-wise improvement in matching the waveform data applying a formalism discussed in Ji et al. (2002). The first model referred to as Phase I is essentially an automated solution where a simple fault plane (300 km long) is fixed agreeing with CMT (Harvard) solution (strike 298 dip =86) assuming the PDE epicenter. The fit to the initial P waves does not work since they do not display a strike-slip polarity pattern. Thus, to continue we added a thrusting event (Phase II) following roughly the fault geometry of the Denali fault based on DEM topography map. While this produced some improvements, major misfits still remained. Before proceeding with Phase III, we did some homework on a foreshock, the Mw=6.7 Nenana event. After modeling this strike-slip event as a distributed fault, we used this relatively simple event to calibrate paths where shifts in P-waves and SH-waves ranged up to 4 and 8 sec respectively. Applying these corrections revealed some discrepancies in the rupture initiation. To produce a consistent picture requires 4 fault segments A, B, C and D. A weak rupture may initiate on a strike-slip Denali fault branch A at a depth of 10 km where a low angle thrust fault plane B intersects A. After about 2 sec, a major event occurred on plane B (strike=221, dip=35) and dominated the rupture of next 8 sec. When rupture B reaches the surface at about 10 sec after initiation, the major portion of the Denali fault (segment C) ruptured eastward with a relatively fast velocity (3 km/sec) producing a large slip concentration (up to 9 m at a depth of 10 km). The surface slip is about 7 km at a 20 km long segment. This feature is near the intersection of the Denali fault and the Totichunda fault (branch D). The rupture on D is relatively

  8. Earthquake Activities Along the Strike-Slip Fault System on the Thailand-Myanmar Border

    Directory of Open Access Journals (Sweden)

    Santi Pailoplee

    2014-01-01

    Full Text Available This study investigates the present-day seismicity along the strike-slip fault system on the Thailand-Myanmar border. Using the earthquake catalogue the earthquake parameters representing seismic activities were evaluated in terms of the possible maximum magnitude, return period and earthquake occurrence probabilities. Three different hazardous areas could be distinguished from the obtained results. The most seismic-prone area was located along the northern segment of the fault system and can generate earthquakes of magnitude 5.0, 5.8, and 6.8 mb in the next 5, 10, and 50 years, respectively. The second most-prone area was the southern segment where earthquakes of magnitude 5.0, 6.0, and 7.0 mb might be generated every 18, 60, and 300 years, respectively. For the central segment, there was less than 30 and 10% probability that 6.0- and 7.0-mb earthquakes will be generated in the next 50 years. With regards to the significant infrastructures (dams in the vicinity, the operational Wachiralongkorn dam is situated in a low seismic hazard area with a return period of around 30 - 3000 years for a 5.0 - 7.0 mb earthquake. In contrast, the Hut Gyi, Srinakarin and Tha Thung Na dams are seismically at risk for earthquakes of mb 6.4 - 6.5 being generated in the next 50 years. Plans for a seismic-retrofit should therefore be completed and implemented while seismic monitoring in this region is indispensable.

  9. Kinematic Analysis of Fault-Slip Data in the Central Range of Papua, Indonesia

    Directory of Open Access Journals (Sweden)

    Benyamin Sapiie

    2016-01-01

    Full Text Available DOI:10.17014/ijog.3.1.1-16Most of the Cenozoic tectonic evolution in New Guinea is a result of obliquely convergent motion that ledto an arc-continent collision between the Australian and Pacific Plates. The Gunung Bijih (Ertsberg Mining District(GBMD is located in the Central Range of Papua, in the western half of the island of New Guinea. This study presentsthe results of detailed structural mapping concentrated on analyzing fault-slip data along a 15-km traverse of theHeavy Equipment Access Trail (HEAT and the Grasberg mine access road, providing new information concerning thedeformation in the GBMD and the Cenozoic structural evolution of the Central Range. Structural analysis indicatesthat two distinct stages of deformation have occurred since ~12 Ma. The first stage generated a series of en-echelonNW-trending (π-fold axis = 300° folds and a few reverse faults. The second stage resulted in a significant left-lateralstrike-slip faulting sub-parallel to the regional strike of upturned bedding. Kinematic analysis reveals that the areasbetween the major strike-slip faults form structural domains that are remarkably uniform in character. The changein deformation styles from contractional to a strike-slip offset is explained as a result from a change in the relativeplate motion between the Pacific and Australian Plates at ~4 Ma. From ~4 - 2 Ma, transform motion along an ~ 270°trend caused a left-lateral strike-slip offset, and reactivated portions of pre-existing reverse faults. This action had aprofound effect on magma emplacement and hydrothermal activity.

  10. The last interglacial period at Guantanamo Bay, Cuba and an estimate of late Quaternary tectonic uplift rate in a strike-slip regime

    Science.gov (United States)

    Schweig, E. S.; Muhs, D. R.; Simmons, K. R.; Halley, R. B.

    2015-12-01

    Guantanamo Bay, Cuba is an area dominated by a strike-slip tectonic regime and is therefore expected to have very low Quaternary uplift rates. We tested this hypothesis by study of an unusually well preserved emergent reef terrace around the bay. Up to 12 m of unaltered, growth-position reef corals are exposed at about 40 sections examined around ˜40 km of coastline. Maximum reef elevations in the protected, inner part of the bay are ˜11-12 m, whereas outer-coast shoreline angles of wave-cut benches are as high as ˜14 m. Fifty uranium-series analyses of unrecrystallized corals from six localities yield ages ranging from ˜134 ka to ˜115 ka, when adjusted for small biases due to slightly elevated initial 234U/238U values. Thus, ages of corals correlate this reef to the peak of the last interglacial period, marine isotope stage (MIS) 5.5. Previously, we dated the Key Largo Limestone to the same high-sea stand in the tectonically stable Florida Keys. Estimates of paleo-sea level during MIS 5.5 in the Florida Keys are ~6.6 to 8.3 m above present. Assuming a similar paleo-sea level in Cuba, this yields a long-term tectonic uplift rate of 0.04-0.06 m/ka over the past ~120 ka. This estimate supports the hypothesis that the tectonic uplift rate should be low in this strike-slip regime. Nevertheless, on the southeast coast of Cuba, east of our study area, we have observed flights of multiple marine terraces, suggesting either (1) a higher uplift rate or (2) an unusually well-preserved record of pre-MIS 5.5 terraces not observed at Guantanamo Bay.

  11. Fault-Slip Data Analysis and Cover Versus Basement Fracture Patterns - Implications for Subsurface Technical Processes in Thuringia, Germany

    Science.gov (United States)

    Kasch, N.; Kley, J.; Navabpour, P.; Siegburg, M.; Malz, A.

    2014-12-01

    Recent investigations in Thuringia, Central Germany, focus on the potential for carbon sequestration, groundwater supply and geothermal energy. We report on the results of an integrated fault-slip data analysis to characterize the geometries and kinematics of systematic fractures in contrasting basement and cover rock lithologies. The lithostratigraphy of the area comprises locally exposed crystalline rocks and intermittently overlying Permian volcanic and clastic sedimentary rocks, together referred to as basement. A Late Permian sequence of evaporites, carbonates and shale constitutes the transition to the continuous sedimentary cover of Triassic age. Major NW-SE-striking fault zones and minor NNE-SSW-striking faults affect this stratigraphic succession. These characteristic narrow deforming areas ( 15 km) non-deforming areas suggesting localized zones of mechanical weakness, which can be confirmed by the frequent reactivation of single fault strands. Along the major fault zones, the basement and cover contain dominant inclined to sub-vertical NW-SE-striking fractures. These fractures indicate successive normal, dextral strike-slip and reverse senses of slip, evidencing events of NNE-SSW extension and contraction. Another system of mostly sub-vertical NNW-SSE- and NE-SW-striking conjugate strike-slip faults mainly developed within the cover implies NNE-SSW contraction and WNW-ESE extension. Earthquake focal mechanisms and in-situ stress measurements reveal a NW-SE trend for the modern SHmax. Nevertheless, fractures and fault-slip indicators are rare in the non-deforming areas, which characterizes Thuringia as a dual domain of (1) large unfractured areas and (2) narrow zones of high potential for technical applications. Our data therefore provide a basis for estimation of slip and dilation tendency of the contrasting fractures in the basement and cover under the present-day stress field, which must be taken into account for different subsurface technical

  12. Influence of slip-surface geometry on earth-flow deformation, Montaguto earth flow, southern Italy

    Science.gov (United States)

    Guerriero, L.; Coe, Jeffrey A.; Revellio, P.; Grelle, G.; Pinto, F.; Guadagno, F.

    2016-01-01

    We investigated relations between slip-surface geometry and deformational structures and hydrologic features at the Montaguto earth flow in southern Italy between 1954 and 2010. We used 25 boreholes, 15 static cone-penetration tests, and 22 shallow-seismic profiles to define the geometry of basal- and lateral-slip surfaces; and 9 multitemporal maps to quantify the spatial and temporal distribution of normal faults, thrust faults, back-tilted surfaces, strike-slip faults, flank ridges, folds, ponds, and springs. We infer that the slip surface is a repeating series of steeply sloping surfaces (risers) and gently sloping surfaces (treads). Stretching of earth-flow material created normal faults at risers, and shortening of earth-flow material created thrust faults, back-tilted surfaces, and ponds at treads. Individual pairs of risers and treads formed quasi-discrete kinematic zones within the earth flow that operated in unison to transmit pulses of sediment along the length of the flow. The locations of strike-slip faults, flank ridges, and folds were not controlled by basal-slip surface topography but were instead dependent on earth-flow volume and lateral changes in the direction of the earth-flow travel path. The earth-flow travel path was strongly influenced by inactive earth-flow deposits and pre-earth-flow drainages whose positions were determined by tectonic structures. The implications of our results that may be applicable to other earth flows are that structures with strikes normal to the direction of earth-flow motion (e.g., normal faults and thrust faults) can be used as a guide to the geometry of basal-slip surfaces, but that depths to the slip surface (i.e., the thickness of an earth flow) will vary as sediment pulses are transmitted through a flow.

  13. Simulation of engine auxiliary drive V-belt slip motion. Part 1. Development of belt slip model; Engine hoki V belt slip kyodo no simulation. 1. Belt slip model no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kurisu, T [Mazda Motor Corp., Hiroshima (Japan)

    1997-10-01

    V-belts are widely used for driving auxiliary components of an engine. Inadequet design of such belt system sometimes results in troubles such as belt squeak, side rubber separation and/or bottom rubber crack. However, there has been no design tools which can predict belt slip quantitatively. The author developed a motion simulation program of Auxiliary Drive V-Belt System considering belt slip. The program showed good prediction accuracy for belt slip motion. This paper describes the simulation model. 1 ref., 12 figs.

  14. Structure of the Melajo clay near Arima, Trinidad and strike-slip motion in the El Pilar fault zone

    Science.gov (United States)

    Robertson, P.; Burke, K.; Wadge, G.

    1985-01-01

    No consensus has yet emerged on the sense, timing and amount of motion in the El Pilar fault zone. As a contribution to the study of this problem, a critical area within the zone in North Central Trinidad has been mapped. On the basis of the mapping, it is concluded that the El Pilar zone has been active in right-lateral strike-slip motion during the Pleistocene. Recognition of structural styles akin to those of the mapped area leads to the suggestion that the El Pilar zone is part of a 300 km wide plate boundary zone extending from the Orinoco delta northward to Grenada. Lateral motion of the Caribbean plate with respect to South America has been suggested to amount to 1900 km in the last 38 Ma. Part of this displacement since the Miocene can be readily accommodated within the broad zone identified here. No one fault system need account for more than a fraction of the total motion and all faults need not be active simultaneously.

  15. The geometry of pull-apart basins in the southern part of Sumatran strike-slip fault zone

    Science.gov (United States)

    Aribowo, Sonny

    2018-02-01

    Models of pull-apart basin geometry have been described by many previous studies in a variety tectonic setting. 2D geometry of Ranau Lake represents a pull-apart basin in the Sumatran Fault Zone. However, there are unclear geomorphic traces of two sub-parallel overlapping strike-slip faults in the boundary of the lake. Nonetheless, clear geomorphic traces that parallel to Kumering Segment of the Sumatran Fault are considered as inactive faults in the southern side of the lake. I demonstrate the angular characteristics of the Ranau Lake and Suoh complex pull-apart basins and compare with pull-apart basin examples from published studies. I use digital elevation model (DEM) image to sketch the shape of the depression of Ranau Lake and Suoh Valley and measure 2D geometry of pull-apart basins. This study shows that Ranau Lake is not a pull-apart basin, and the pull-apart basin is actually located in the eastern side of the lake. Since there is a clear connection between pull-apart basin and volcanic activity in Sumatra, I also predict that the unclear trace of the pull-apart basin near Ranau Lake may be covered by Ranau Caldera and Seminung volcanic products.

  16. Variations in strength and slip rate along the san andreas fault system.

    Science.gov (United States)

    Jones, C H; Wesnousky, S G

    1992-04-03

    Convergence across the San Andreas fault (SAF) system is partitioned between strike-slip motion on the vertical SAF and oblique-slip motion on parallel dip-slip faults, as illustrated by the recent magnitude M(s) = 6.0 Palm Springs, M(s) = 6.7 Coalinga, and M(s) = 7.1 Loma Prieta earthquakes. If the partitioning of slip minimizes the work done against friction, the direction of slip during these recent earthquakes depends primarily on fault dip and indicates that the normal stress coefficient and frictional coefficient (micro) vary among the faults. Additionally, accounting for the active dip-slip faults reduces estimates of fault slip rates along the vertical trace of the SAF by about 50 percent in the Loma Prieta and 100 percent in the North Palm Springs segments.

  17. Analogue modelling on the interaction between shallow magma intrusion and a strike-slip fault: Application on the Middle Triassic Monzoni Intrusive Complex (Dolomites, Italy)

    Science.gov (United States)

    Michail, Maria; Coltorti, Massimo; Gianolla, Piero; Riva, Alberto; Rosenau, Matthias; Bonadiman, Costanza; Galland, Olivier; Guldstrand, Frank; Thordén Haug, Øystein; Rudolf, Michael; Schmiedel, Tobias

    2017-04-01

    The southwestern part of the Dolomites in Northern Italy has undergone a short-lived Ladinian (Middle Triassic) tectono-magmatic event, forming a series of significant magmatic features. These intrusive bodies deformed and metamorphosed the Permo-Triassic carbonate sedimentary framework. In this study we focus on the tectono-magmatic evolution of the shallow shoshonitic Monzoni Intrusive Complex of this Ladinian event (ca 237 Ma), covering an area of 20 km^2. This NW-SE elongated intrusive structure (5 km length) shows an orogenic magmatic affinity which is in contrast to the tectonic regime at the time of intrusion. Strain analysis shows anorogenic transtensional displacement in accordance with the ENE-WSW extensional pattern in the central Dolomites during the Ladinian. Field interpretations led to a detailed description of the regional stratigraphic sequence and the structural features of the study area. However, the geodynamic context of this magmatism and the influence of the inherited strike-slip fault on the intrusion, are still in question. To better understand the specific natural prototype and the general mechanisms of magma emplacement in tectonically active areas, we performed analogue experiments defined by, but not limited to, first order field observations. We have conducted a systematic series of experiments in different tectonic regimes (static conditions, strike-slip, transtension). We varied the ratio of viscous to brittle stresses between magma and country rock, by injecting Newtonian fluids both of high and low viscosity (i.e. silicone oil/vegetable oil) into granular materials of varying cohesion (sand, silica flour, glass beads). The evolving surface and side view of the experiments were monitored by photogrammetric techniques for strain analyses and topographic evolution. In our case, the combination of the results from field and analogue experiments brings new insights regarding the tectonic regime, the geometry of the intrusive body, and

  18. Segmentation of Slow Slip Events in South Central Alaska Possibly Controlled by a Subducted Oceanic Plateau

    Science.gov (United States)

    Li, Haotian; Wei, Meng; Li, Duo; Liu, Yajing; Kim, YoungHee; Zhou, Shiyong

    2018-01-01

    Recent GPS observations show that slow slip events in south central Alaska are segmented along strike. Here we review several mechanisms that might contribute to this segmentation and focus on two: along-strike variation of slab geometry and effective normal stress. We then test them by running numerical simulations in the framework of rate-and-state friction with a nonplanar fault geometry. Results show that the segmentation is most likely related to the along-strike variation of the effective normal stress on the fault plane caused by the Yakutat Plateau. The Yakutat Plateau could affect the effective normal stress by either lowering the pore pressure in Upper Cook Inlet due to less fluids release or increasing the normal stress due to the extra buoyancy caused by the subducted Yakutat Plateau. We prefer the latter explanation because it is consistent with the relative amplitudes of the effective normal stress in Upper and Lower Cook Inlet and there is very little along-strike variation in Vp/Vs ratio in the fault zone from receiver function analysis. However, we cannot exclude the possibility that the difference in effective normal stress results from along-strike variation of pore pressure due to the uncertainties in the Vp/Vs estimates. Our work implies that a structural anomaly can have a long-lived effect on the subduction zone slip behavior and might be a driving factor on along-strike segmentation of slow slip events.

  19. Buried shallow fault slip from the South Napa earthquake revealed by near-field geodesy.

    Science.gov (United States)

    Brooks, Benjamin A; Minson, Sarah E; Glennie, Craig L; Nevitt, Johanna M; Dawson, Tim; Rubin, Ron; Ericksen, Todd L; Lockner, David; Hudnut, Kenneth; Langenheim, Victoria; Lutz, Andrew; Mareschal, Maxime; Murray, Jessica; Schwartz, David; Zaccone, Dana

    2017-07-01

    Earthquake-related fault slip in the upper hundreds of meters of Earth's surface has remained largely unstudied because of challenges measuring deformation in the near field of a fault rupture. We analyze centimeter-scale accuracy mobile laser scanning (MLS) data of deformed vine rows within ±300 m of the principal surface expression of the M (magnitude) 6.0 2014 South Napa earthquake. Rather than assuming surface displacement equivalence to fault slip, we invert the near-field data with a model that allows for, but does not require, the fault to be buried below the surface. The inversion maps the position on a preexisting fault plane of a slip front that terminates ~3 to 25 m below the surface coseismically and within a few hours postseismically. The lack of surface-breaching fault slip is verified by two trenches. We estimate near-surface slip ranging from ~0.5 to 1.25 m. Surface displacement can underestimate fault slip by as much as 30%. This implies that similar biases could be present in short-term geologic slip rates used in seismic hazard analyses. Along strike and downdip, we find deficits in slip: The along-strike deficit is erased after ~1 month by afterslip. We find no evidence of off-fault deformation and conclude that the downdip shallow slip deficit for this event is likely an artifact. As near-field geodetic data rapidly proliferate and will become commonplace, we suggest that analyses of near-surface fault rupture should also use more sophisticated mechanical models and subsurface geomechanical tests.

  20. Buried shallow fault slip from the South Napa earthquake revealed by near-field geodesy

    Science.gov (United States)

    Brooks, Benjamin A.; Minson, Sarah E.; Glennie, Craig L.; Nevitt, Johanna M.; Dawson, Tim; Rubin, Ron; Ericksen, Todd L.; Lockner, David; Hudnut, Kenneth; Langenheim, Victoria; Lutz, Andrew; Mareschal, Maxime; Murray, Jessica; Schwartz, David; Zaccone, Dana

    2017-01-01

    Earthquake-related fault slip in the upper hundreds of meters of Earth’s surface has remained largely unstudied because of challenges measuring deformation in the near field of a fault rupture. We analyze centimeter-scale accuracy mobile laser scanning (MLS) data of deformed vine rows within ±300 m of the principal surface expression of the M (magnitude) 6.0 2014 South Napa earthquake. Rather than assuming surface displacement equivalence to fault slip, we invert the near-field data with a model that allows for, but does not require, the fault to be buried below the surface. The inversion maps the position on a preexisting fault plane of a slip front that terminates ~3 to 25 m below the surface coseismically and within a few hours postseismically. The lack of surface-breaching fault slip is verified by two trenches. We estimate near-surface slip ranging from ~0.5 to 1.25 m. Surface displacement can underestimate fault slip by as much as 30%. This implies that similar biases could be present in short-term geologic slip rates used in seismic hazard analyses. Along strike and downdip, we find deficits in slip: The along-strike deficit is erased after ~1 month by afterslip. We find no evidence of off-fault deformation and conclude that the downdip shallow slip deficit for this event is likely an artifact. As near-field geodetic data rapidly proliferate and will become commonplace, we suggest that analyses of near-surface fault rupture should also use more sophisticated mechanical models and subsurface geomechanical tests. PMID:28782026

  1. Striking Clepsydras

    Science.gov (United States)

    Nam, Moon-Hyon

    The term "Striking Clepsydra" is a shortened translation of the Korean name Jagyeongnu (自擊漏, tzu-chi lou in Chinese, literally "automatic-striking water-clock"). It was given to the two monumental time-keeping installations built by chief court engineer Yeong-sil Jang in AD 1432-38 under King Sejong (r. AD 1418-50) of the Joseon dynasty (1392-1910) in Seoul. These were housed separately in the Gyeongbok palace complex as major installations of the Royal Observatory Ganuidae equipped during 1432-38. One was the Striking Palace Clepsydra Borugangnu that was employed as the standard time-keeper from 1434, and the other was the Striking Heavenly Clepsydra Heumgyeonggangnu that was put into use not only as the symbol of Neo-Confucian ideology from 1438, but also as a demonstrational orrery and time-keeper. These were restored several times through the dynasty after loss by fires and warfare, and clepsydra-making technologies were succeeded by the development of armillary clocks in 1669. The National Palace Museum of Korea recreated the 1434 Striking Palace Clepsydra of King Sejong, and the replica was installed for permanent exhibition from November 2007.

  2. Misbheaving Faults: The Expanding Role of Geodetic Imaging in Unraveling Unexpected Fault Slip Behavior

    Science.gov (United States)

    Barnhart, W. D.; Briggs, R.

    2015-12-01

    Geodetic imaging techniques enable researchers to "see" details of fault rupture that cannot be captured by complementary tools such as seismology and field studies, thus providing increasingly detailed information about surface strain, slip kinematics, and how an earthquake may be transcribed into the geological record. For example, the recent Haiti, Sierra El Mayor, and Nepal earthquakes illustrate the fundamental role of geodetic observations in recording blind ruptures where purely geological and seismological studies provided incomplete views of rupture kinematics. Traditional earthquake hazard analyses typically rely on sparse paleoseismic observations and incomplete mapping, simple assumptions of slip kinematics from Andersonian faulting, and earthquake analogs to characterize the probabilities of forthcoming ruptures and the severity of ground accelerations. Spatially dense geodetic observations in turn help to identify where these prevailing assumptions regarding fault behavior break down and highlight new and unexpected kinematic slip behavior. Here, we focus on three key contributions of space geodetic observations to the analysis of co-seismic deformation: identifying near-surface co-seismic slip where no easily recognized fault rupture exists; discerning non-Andersonian faulting styles; and quantifying distributed, off-fault deformation. The 2013 Balochistan strike slip earthquake in Pakistan illuminates how space geodesy precisely images non-Andersonian behavior and off-fault deformation. Through analysis of high-resolution optical imagery and DEMs, evidence emerges that a single fault map slip as both a strike slip and dip slip fault across multiple seismic cycles. These observations likewise enable us to quantify on-fault deformation, which account for ~72% of the displacements in this earthquake. Nonetheless, the spatial distribution of on- and off-fault deformation in this event is highly spatially variable- a complicating factor for comparisons

  3. 2-D Deformation analysis of a half-space due to a long dip-slip fault ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    tic deformation in a uniform half-space due to long faults has been attempted by a number of researchers. Singh and Rani (1996) presented step- by-step progress made in the direction of crustal deformation modeling associated with strike-slip and dip-slip faulting in the earth. Cohen (1996) gave convenient formulas for ...

  4. Magmatic control along a strike-slip volcanic arc: The central Aeolian arc (Italy)

    KAUST Repository

    Ruch, Joel; Vezzoli, L.; De Rosa, R.; Di Lorenzo, R.; Acocella, V

    2016-01-01

    -slip motion; consistent with an E-W extension direction, with minor dextral and sinistral shear. Our data highlight six eruptive periods during the last 55 ka, which allow considering both islands as a single magmatic system, in which tectonic and magmatic

  5. Hematite (U-Th)/He thermochronometry constrains intraplate strike-slip faulting on the Kuh-e-Faghan Fault, central Iran

    Science.gov (United States)

    Calzolari, Gabriele; Rossetti, Federico; Ault, Alexis K.; Lucci, Federico; Olivetti, Valerio; Nozaem, Reza

    2018-03-01

    The Kuh-e-Faghan strike-slip fault system (KFF), located to the northern edge of the Lut Block in central Iran, developed through a Neogene-Quaternary pulsed history of eastward fault propagation and fault-related exhumation. This system is a consequence of the residual stresses transmitted from the Arabia-Eurasia convergent plate boundary. Here we integrate structural and textural analysis with new and previously published apatite fission-track (AFT) and apatite (U-Th)/He (apatite He) results, chlorite thermomentry, and hematite (U-Th)/He data from hematite-coated brittle fault surfaces to constrain the timing of tectonic activity and refine patterns of late Miocene-Pliocene burial and exhumation associated with the propagation of the KFF. Twenty-nine hematite (U-Th)/He (hematite He) dates from three striated hematite coated slip surfaces from the KFF fault core and damage zone yield individual dates from 12-2 Ma. Petrographic analysis and chlorite thermometry of a polyphase, fossil fluid system in the KFF fault core document that fluid circulation and mineralization transitioned from a closed system characterized by pressure solution and calcite growth to an open system characterized by hot hydrothermal (T = 239 ± 10 °C) fluids and hematite formation. Hematite microtextures and grain size analysis reveal primary and secondary syntectonic hematite fabrics, no evidence of hematite comminution and similar hematite He closure temperatures ( 60-85 °C) in each sample. Integration of these results with thermal history modeling of AFT and apatite He data shows that KFF activity in the late Miocene is characterized by an early stage of fault nucleation, fluid circulation, hematite mineralization, and eastward propagation not associated with vertical movement that lasted from 12 to 7 Ma. Hematite He, AFT, and apatite He data track a second phase of fault system activity involving fault-related exhumation initiating at 7 Ma and continuing until present time. Our new data

  6. The use of Stress Tensor Discriminator Faults in separating heterogeneous fault-slip data with best-fit stress inversion methods. II. Compressional stress regimes

    Science.gov (United States)

    Tranos, Markos D.

    2018-02-01

    Synthetic heterogeneous fault-slip data as driven by Andersonian compressional stress tensors were used to examine the efficiency of best-fit stress inversion methods in separating them. Heterogeneous fault-slip data are separated only if (a) they have been driven by stress tensors defining 'hybrid' compression (R constitute a necessary discriminatory tool for the establishment and comparison of two compressional stress tensors determined by a best-fit stress inversion method. The best-fit stress inversion methods are not able to determine more than one 'real' compressional stress tensor, as far as the thrust stacking in an orogeny is concerned. They can only possibly discern stress differences in the late-orogenic faulting processes, but not between the main- and late-orogenic stages.

  7. Pseudodynamic Source Characterization for Strike-Slip Faulting Including Stress Heterogeneity and Super-Shear Ruptures

    KAUST Repository

    Mena, B.; Dalguer, L. A.; Mai, Paul Martin

    2012-01-01

    . (2004), we propose new relationships for PD models for moderate‐to‐large strike‐slip earthquakes that include local supershear rupture speed due to stress heterogeneities. We conduct dynamic rupture simulations using stochastic initial stress

  8. Development of a slip sensor using separable bilayer with Ecoflex-NBR film

    Science.gov (United States)

    Kim, Sung Joon; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, Ja Choon

    2017-04-01

    Polymer film-type slip sensor is presented by using novel working principle rather than measuring micro-vibration. The sensor is comprised of bilayer with Ecoflex and NBR(acrylonitrile butadiene rubber) films divided by di-electric. When slip occur on surface, bilayer have relative displacement from each other because friction-induced vibration make a clearance between two layers. This displacement can be obtained by capacitance difference. CNT(carbon nanotube) was employed for electrode because of flexible and stretchable characteristics. Also normal and shear force can be decoupled by the working principle. To verify developed sensor, slip test apparatus was designed and experiments were conducted.

  9. Nonlinear dynamical triggering of slow slip

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Paul A [Los Alamos National Laboratory; Knuth, Matthew W [WISCONSIN; Kaproth, Bryan M [PENN STATE; Carpenter, Brett [PENN STATE; Guyer, Robert A [Los Alamos National Laboratory; Le Bas, Pierre - Yves [Los Alamos National Laboratory; Daub, Eric G [Los Alamos National Laboratory; Marone, Chris [PENN STATE

    2010-12-10

    Among the most fascinating, recent discoveries in seismology have been the phenomena of triggered slip, including triggered earthquakes and triggered-tremor, as well as triggered slow, silent-slip during which no seismic energy is radiated. Because fault nucleation depths cannot be probed directly, the physical regimes in which these phenomena occur are poorly understood. Thus determining physical properties that control diverse types of triggered fault sliding and what frictional constitutive laws govern triggered faulting variability is challenging. We are characterizing the physical controls of triggered faulting with the goal of developing constitutive relations by conducting laboratory and numerical modeling experiments in sheared granular media at varying load conditions. In order to simulate granular fault zone gouge in the laboratory, glass beads are sheared in a double-direct configuration under constant normal stress, while subject to transient perturbation by acoustic waves. We find that triggered, slow, silent-slip occurs at very small confining loads ({approx}1-3 MPa) that are smaller than those where dynamic earthquake triggering takes place (4-7 MPa), and that triggered slow-slip is associated with bursts of LFE-like acoustic emission. Experimental evidence suggests that the nonlinear dynamical response of the gouge material induced by dynamic waves may be responsible for the triggered slip behavior: the slip-duration, stress-drop and along-strike slip displacement are proportional to the triggering wave amplitude. Further, we observe a shear-modulus decrease corresponding to dynamic-wave triggering relative to the shear modulus of stick-slips. Modulus decrease in response to dynamical wave amplitudes of roughly a microstrain and above is a hallmark of elastic nonlinear behavior. We believe that the dynamical waves increase the material non-affine elastic deformation during shearing, simultaneously leading to instability and slow-slip. The inferred

  10. Combining Earthquake Focal Mechanism Inversion and Coulomb Friction Law to Yield Tectonic Stress Magnitudes in Strike-slip Faulting Regime

    Science.gov (United States)

    Soh, I.; Chang, C.

    2017-12-01

    The techniques for estimating present-day stress states by inverting multiple earthquake focal mechanism solutions (FMS) provide orientations of the three principal stresses and their relative magnitudes. In order to estimate absolute magnitudes of the stresses that are generally required to analyze faulting mechanics, we combine the relative stress magnitude parameter (R-value) derived from the inversion process and the concept of frictional equilibrium of stress state defined by Coulomb friction law. The stress inversion in Korean Peninsula using 152 FMS data (magnitude≥2.5) conducted at regularly spaced grid points yields a consistent strike-slip faulting regime in which the maximum (S1) and the minimum (S3) principal stresses act in horizontal planes (with an S1 azimuth in ENE-WSW) and the intermediate principal stress (S2) close to vertical. However, R-value varies from 0.28 to 0.75 depending on locations, systematically increasing eastward. Based on the assumptions that the vertical stress is lithostatic, pore pressure is hydrostatic, and the maximum differential stress (S1-S3) is limited by Byerlee's friction of optimally oriented faults for slip, we estimate absolute magnitudes of the two horizontal principal stresses using R-value. As R-value increases, so do the magnitudes of the horizontal stresses. Our estimation of the stress magnitudes shows that the maximum horizontal principal stress (S1) normalized by vertical stress tends to increase from 1.3 in the west to 1.8 in the east. The estimated variation of stress magnitudes is compatible with distinct clustering of faulting types in different regions. Normal faulting events are densely populated in the west region where the horizontal stress is relatively low, whereas numerous reverse faulting events prevail in the east offshore where the horizontal stress is relatively high. Such a characteristic distribution of distinct faulting types in different regions can only be explained in terms of stress

  11. Foreshocks during the nucleation of stick-slip instability

    Science.gov (United States)

    McLaskey, Gregory C.; Kilgore, Brian D.

    2013-01-01

    We report on laboratory experiments which investigate interactions between aseismic slip, stress changes, and seismicity on a critically stressed fault during the nucleation of stick-slip instability. We monitor quasi-static and dynamic changes in local shear stress and fault slip with arrays of gages deployed along a simulated strike-slip fault (2 m long and 0.4 m deep) in a saw cut sample of Sierra White granite. With 14 piezoelectric sensors, we simultaneously monitor seismic signals produced during the nucleation phase and subsequent dynamic rupture. We observe localized aseismic fault slip in an approximately meter-sized zone in the center of the fault, while the ends of the fault remain locked. Clusters of high-frequency foreshocks (Mw ~ −6.5 to −5.0) can occur in this slowly slipping zone 5–50 ms prior to the initiation of dynamic rupture; their occurrence appears to be dependent on the rate at which local shear stress is applied to the fault. The meter-sized nucleation zone is generally consistent with theoretical estimates, but source radii of the foreshocks (2 to 70 mm) are 1 to 2 orders of magnitude smaller than the theoretical minimum length scale over which earthquake nucleation can occur. We propose that frictional stability and the transition between seismic and aseismic slip are modulated by local stressing rate and that fault sections, which would typically slip aseismically, may radiate seismic waves if they are rapidly stressed. Fault behavior of this type may provide physical insight into the mechanics of foreshocks, tremor, repeating earthquake sequences, and a minimum earthquake source dimension.

  12. Combined effects of magnetic field and partial slip on obliquely striking rheological fluid over a stretching surface

    International Nuclear Information System (INIS)

    Nadeem, S.; Mehmood, Rashid; Akbar, Noreen Sher

    2015-01-01

    This study explores the collective effects of partial slip and transverse magnetic field on an oblique stagnation point flow of a rheological fluid. The prevailing momentum equations are designed by manipulating Casson fluid model. By applying the suitable similarity transformations, the governing system of equations is being transformed into coupled nonlinear ordinary differential equations. The resulting system is handled numerically through midpoint integration scheme together with Richardson's extrapolation. It is found that both normal and tangential velocity profiles decreases with an increase in magnetic field as well as slip parameter. Streamlines pattern are presented to study the actual impact of slip mechanism and magnetic field on the oblique flow. A suitable comparison with the previous literature is also provided to confirm the accuracy of present results for the limiting case. - Highlights: • The MHD 2-Dimensional flow of Casson fluid is present. • Streamlines pattern are presented to study the actual impact of slip mechanism and magnetic field on the oblique flow. • The prevailing momentum equations are designed by manipulating Casson fluid model. • Obtained coupled ordinary differential equations are investigated numerically. • Graphical results are obtained for each physical parameter

  13. Seismic Evidence for Conjugate Slip and Block Rotation Within the San Andreas Fault System, Southern California

    Science.gov (United States)

    Nicholson, Craig; Seeber, Leonardo; Williams, Patrick; Sykes, Lynn R.

    1986-08-01

    The pattern of seismicity in southern California indicates that much of the activity is presently occurring on secondary structures, several of which are oriented nearly orthogonal to the strikes of the major through-going faults. Slip along these secondary transverse features is predominantly left-lateral and is consistent with the reactivation of conjugate faults by the current regional stress field. Near the intersection of the San Jacinto and San Andreas faults, however, these active left-lateral faults appear to define a set of small crustal blocks, which in conjunction with both normal and reverse faulting earthquakes, suggests contemporary clockwise rotation as a result of regional right-lateral shear. Other left-lateral faults representing additional rotating block systems are identified in adjacent areas from geologic and seismologic data. Many of these structures predate the modern San Andreas system and may control the pattern of strain accumulation in southern California. Geodetic and paleomagnetic evidence confirm that block rotation by strike-slip faulting is nearly ubiquitous, particularly in areas where shear is distributed, and that it accommodates both short-term elastic and long-term nonelastic strain. A rotating block model accounts for a number of structural styles characteristic of strike-slip deformation in California, including: variable slip rates and alternating transtensional and transpressional features observed along strike of major wrench faults; domains of evenly-spaced antithetic faults that terminate against major fault boundaries; continued development of bends in faults with large lateral displacements; anomalous focal mechanisms; and differential uplift in areas otherwise expected to experience extension and subsidence. Since block rotation requires a detachment surface at depth to permit rotational movement, low-angle structures like detachments, of either local or regional extent, may be involved in the contemporary strike-slip

  14. Large-magnitude Dextral Slip on the Wairarapa Fault, New Zealand

    Science.gov (United States)

    Rodgers, D. W.; Little, T.

    2004-12-01

    Dextral slip associated with an 1855 Ms 8.0+ event on the Wairarapa fault near Wellington, New Zealand was reported to be 12+/-1 m along a rupture length of at least 148km (Grapes, 1999), one of the largest single-event strike-slip offsets documented worldwide. Initial results from a new study involving detailed neotectonic mapping and microtopographic surveys of offset landforms (including many beheaded, inactive streams) strongly suggest that dextral slip was as much as 50% greater than previously measured. 1855 surface ruptures were mapped with certainty where a linear scarp characterized by steep slopes (30-90°) and exposed alluvium cuts across active or inactive stream channels. The fifteen individual strands comprising the Wairarapa fault zone that we have mapped to date are 1200+/-700 m long and typically left-stepping. Slip in the stepover zones between these strands is distributed amongst two or more ruptures and intervening anticlines, a situation that causes along-strike variations in slip and which locally complicates the interpretation of 1855 displacement. We focused on seven of the best-preserved sites where low-discharge streams are disrupted by the fault zone, including five that had been previously attributed by Grapes (1999) to coseismic slip during the 1855 earthquake. One of these (Pigeon Bush) includes two sequentially displaced, now beheaded linear stream channels, oriented perpendicular to the fault scarp, that preserve distinct offsets with respect to a single deeply incised, originally contiguous gorge on the opposite side of the fault. To quantify the minimum fault displacements at each site, we made 1:500 scale topographic maps employing n = 2,000-10,000 points collected with GPS and laser instrumentation. Measured dextral slip values, here attributed to the 1855 earthquake, include 16.4+/-1.0m (Hinaburn), 12.9+/-2.0m (Cross Creek), 17.2+/-2.5m (Lake Meadows), 18.7+/-1.0m (Pigeon Bush), 13.0+/-1.5m (Pigeon Bush 2), 15.1+/-1.0m (Pigeon

  15. Velocity slip and translational nonequilibrium of ternary gas mixtures in free jet expansions

    International Nuclear Information System (INIS)

    Cattolica, R.J.; Gallagher, R.J.; Anderson, J.B.; Talbot, L.

    1977-05-01

    An aerodynamic isotope separation technique based on the velocity slip between gases in a rarefied flow has been proposed. To evaluate the efficiency of this separation technique, the velocity and translational temperature of the individual species in binary and ternary gas mixtures of argon and neon in helium have been studied in a low density hypersonic free jet. The velocity and temperature of the gas were determined from the Doppler shift and broadening of the fluorescence excited by an electron beam. Velocity slip and translational nonequilibrium were observed over a range of source pressures. A separation factor based on the velocity slip and temperatures was also determined. A comparison of the velocity slip, temperatures, and separation factor with the results of a Monte Carlo simulation of the flow field is presented

  16. Fault zone architecture of a major oblique-slip fault in the Rawil depression, Western Helvetic nappes, Switzerland

    Science.gov (United States)

    Gasser, D.; Mancktelow, N. S.

    2009-04-01

    The Helvetic nappes in the Swiss Alps form a classic fold-and-thrust belt related to overall NNW-directed transport. In western Switzerland, the plunge of nappe fold axes and the regional distribution of units define a broad depression, the Rawil depression, between the culminations of Aiguilles Rouge massif to the SW and Aar massif to the NE. A compilation of data from the literature establishes that, in addition to thrusts related to nappe stacking, the Rawil depression is cross-cut by four sets of brittle faults: (1) SW-NE striking normal faults that strike parallel to the regional fold axis trend, (2) NW-SE striking normal faults and joints that strike perpendicular to the regional fold axis trend, and (3) WNW-ESE striking normal plus dextral oblique-slip faults as well as (4) WSW-ENE striking normal plus dextral oblique-slip faults that both strike oblique to the regional fold axis trend. We studied in detail a beautifully exposed fault from set 3, the Rezli fault zone (RFZ) in the central Wildhorn nappe. The RFZ is a shallow to moderately-dipping (ca. 30-60˚) fault zone with an oblique-slip displacement vector, combining both dextral and normal components. It must have formed in approximately this orientation, because the local orientation of fold axes corresponds to the regional one, as does the generally vertical orientation of extensional joints and veins associated with the regional fault set 2. The fault zone crosscuts four different lithologies: limestone, intercalated marl and limestone, marl and sandstone, and it has a maximum horizontal dextral offset component of ~300 m and a maximum vertical normal offset component of ~200 m. Its internal architecture strongly depends on the lithology in which it developed. In the limestone, it consists of veins, stylolites, cataclasites and cemented gouge, in the intercalated marls and limestones of anastomosing shear zones, brittle fractures, veins and folds, in the marls of anastomosing shear zones, pressure

  17. Spatial Comparisons of Tremor and Slow Slip as a Constraint on Fault Strength in the Northern Cascadia Subduction Zone

    Science.gov (United States)

    Hall, K.; Schmidt, D. A.; Houston, H.

    2017-12-01

    We measure displacement vectors from about 50 or more PANGA 3-component GPS stations to analyze six large ETS events from 2007 - 2016 in northern Cascadia, and invert for slip on a realistic plate interface. Our previous results indicated that significant slip of up to 2 cm occurs 10 to 15 km up-dip of the western edge of tremor beneath the Olympic Peninsula. This far up-dip aseismic slip persists in several of the ETS events. We also find that this offset appears to vary along-strike with a greater offset beneath the Olympic Peninsula and up into the Strait of Juan de Fuca in comparison to lower Puget Sound. To explain this, we explore how properties (temperature and permeability) of the overlying structure may influence fault strength. In our conceptual model, the observation that slip inferred from GPS can extend updip of tremor suggests that updip of the observed edge of tremor, seismogenic patches that could produce tremor and low frequency earthquakes (LFEs) are too strong to fail from the relatively minor amount of far up-dip slow slip. This is consistent with the observation that, within the ETS zone, down-dip LFEs occur frequently, whereas up-dip LFEs occur only during the largest ETS events and are unaffected by tidal stresses until the later stages of an ETS event. This suggests that the up-dip seismogenic patches have a larger discrepancy between their strength and stress states, and therefore require larger stress perturbations (such as those from a propagating ETS slip pulse) to trigger seismic failure. We consider whether lateral variations in overlying structure may explain the along-strike variations in far up-dip aseismic slip. There is an abrupt change in lithology from the meta-sediments of the Olympic accretionary complex to the mafic basalts of the Crescent terrane. The juxtaposition of these different lithologies could potentially explain the along-strike variations in far up-dip aseismic slip. We propose to explore whether relative changes

  18. Stress and slip partitioning during oblique rifting: comparison between data from the Main Ethiopian Rift and laboratory experiments

    Science.gov (United States)

    Corti, G.; Philippon, M.; Sani, F.; Keir, D.

    2012-04-01

    Oblique rifting in the central and northern Main Ethiopian Rift (MER) has resulted in a complex structural pattern characterized by two differently oriented fault systems: a set of NE-SW-trending boundary faults and a system of roughly NNE-SSW-oriented fault swarms affecting the rift floor (Wonji faults). Boundary faults formed oblique to the regional extension vector, likely as a result of the oblique reactivation of a pre-existing deep-seated rheological anisotropy, whereas internal Wonji faults developed sub-orthogonal to the stretching direction. Previous works have successfully reconciled this rift architecture and fault distribution with the long-term plate kinematics; however, at a more local scale, fault-slip and earthquake data reveal significant variations in the orientation the minimum principal stress and related fault-slip direction across the rift valley. Whereas fault measurements indicate a roughly N95°E extension on the axial Wonji faults, a N105°E to N110°E directed minimum principal stress is observed along boundary faults. Both fault-slip data and analysis of seismicity indicate a roughly pure dip-slip motion on the boundary faults, despite their orientation (oblique to the regional extension vector) should result in an oblique displacement. To shed light on the process driving the variability of data derived from fault-slip (and seismicity) analysis we present crustal-scale analogue models of oblique rifting, deformed in a large-capacity centrifuge by using materials and boundary conditions described in several previous modeling works. As in these previous works, the experiments show the diachronous activation of two fault systems, boundary and internal, whose pattern strikingly resemble that observed in previous lithospheric-scale modeling, as well as that described in the MER. Internal faults arrange in two different, en-echelon segments connected by a transfer zone where strike-slip displacement dominates. Whereas internal faults develop

  19. Slicing up the San Francisco Bay Area: Block kinematics and fault slip rates from GPS-derived surface velocities

    Science.gov (United States)

    d'Alessio, M. A.; Johanson, I.A.; Burgmann, R.; Schmidt, D.A.; Murray, M.H.

    2005-01-01

    Observations of surface deformation allow us to determine the kinematics of faults in the San Francisco Bay Area. We present the Bay Area velocity unification (BA??VU??, "bay view"), a compilation of over 200 horizontal surface velocities computed from campaign-style and continuous Global Positioning System (GPS) observations from 1993 to 2003. We interpret this interseismic velocity field using a three-dimensional block model to determine the relative contributions of block motion, elastic strain accumulation, and shallow aseismic creep. The total relative motion between the Pacific plate and the rigid Sierra Nevada/Great Valley (SNGV) microplate is 37.9 ?? 0.6 mm yr-1 directed toward N30.4??W ?? 0.8?? at San Francisco (??2??). Fault slip rates from our preferred model are typically within the error bounds of geologic estimates but provide a better fit to geodetic data (notable right-lateral slip rates in mm yr-1: San Gregorio fault, 2.4 ?? 1.0; West Napa fault, 4.0 ?? 3.0; zone of faulting along the eastern margin of the Coast Range, 5.4 ?? 1.0; and Mount Diablo thrust, 3.9 ?? 1.0 of reverse slip and 4.0 ?? 0.2 of right-lateral strike slip). Slip on the northern Calaveras is partitioned between both the West Napa and Concord/ Green Valley fault systems. The total convergence across the Bay Area is negligible. Poles of rotation for Bay Area blocks progress systematically from the North America-Pacific to North America-SNGV poles. The resulting present-day relative motion cannot explain the strike of most Bay Area faults, but fault strike does loosely correlate with inferred plate motions at the time each fault initiated. Copyright 2005 by the American Geophysical Union.

  20. Spatial Variation of Slip Behavior Beneath the Alaska Peninsula Along Alaska-Aleutian Subduction Zone

    Science.gov (United States)

    Li, Shanshan; Freymueller, Jeffrey T.

    2018-04-01

    We resurveyed preexisting campaign Global Positioning System (GPS) sites and estimated a highly precise GPS velocity field for the Alaska Peninsula. We use the TDEFNODE software to model the slip deficit distribution using the new GPS velocities. We find systematic misfits to the vertical velocities from the optimal model that fits the horizontal velocities well, which cannot be explained by altering the slip distribution, so we use only the horizontal velocities in the study. Locations of three boundaries that mark significant along-strike change in the locking distribution are identified. The Kodiak segment is strongly locked, the Semidi segment is intermediate, the Shumagin segment is weakly locked, and the Sanak segment is dominantly creeping. We suggest that a change in preexisting plate fabric orientation on the downgoing plate has an important control on the along-strike variation in the megathrust locking distribution and subduction seismicity.

  1. Leakage flow-induced vibration of an eccentric tube-in-tube slip joint

    International Nuclear Information System (INIS)

    Mulcahy, T.M.

    1985-08-01

    Eccentricity of a specific slip-joint design separating two cantilevered, telescoping tubes did not create any self-excited lateral vibrations that had not been observed previously for a concentric slip joint. In fact, the eccentricity made instabilities less likely to occur, but only marginally. Most important, design rules previously established to avoid instabilities for the concentric slip joint remain valid for the eccentric slip joint. 6 refs., 9 figs., 2 tabs

  2. A Comparison of Geodetic and Geologic Rates Prior to Large Strike-Slip Earthquakes: A Diversity of Earthquake-Cycle Behaviors?

    Science.gov (United States)

    Dolan, James F.; Meade, Brendan J.

    2017-12-01

    Comparison of preevent geodetic and geologic rates in three large-magnitude (Mw = 7.6-7.9) strike-slip earthquakes reveals a wide range of behaviors. Specifically, geodetic rates of 26-28 mm/yr for the North Anatolian fault along the 1999 MW = 7.6 Izmit rupture are ˜40% faster than Holocene geologic rates. In contrast, geodetic rates of ˜6-8 mm/yr along the Denali fault prior to the 2002 MW = 7.9 Denali earthquake are only approximately half as fast as the latest Pleistocene-Holocene geologic rate of ˜12 mm/yr. In the third example where a sufficiently long pre-earthquake geodetic time series exists, the geodetic and geologic rates along the 2001 MW = 7.8 Kokoxili rupture on the Kunlun fault are approximately equal at ˜11 mm/yr. These results are not readily explicable with extant earthquake-cycle modeling, suggesting that they may instead be due to some combination of regional kinematic fault interactions, temporal variations in the strength of lithospheric-scale shear zones, and/or variations in local relative plate motion rate. Whatever the exact causes of these variable behaviors, these observations indicate that either the ratio of geodetic to geologic rates before an earthquake may not be diagnostic of the time to the next earthquake, as predicted by many rheologically based geodynamic models of earthquake-cycle behavior, or different behaviors characterize different fault systems in a manner that is not yet understood or predictable.

  3. Non-slipping domains of a pulled spool

    International Nuclear Information System (INIS)

    Wagner, Clemens; Vaterlaus, Andreas

    2014-01-01

    We have investigated the pulled spool by considering pulling angles up to 360 ∘ . Our focus was on downward pulling forces with pulling angles in the range of 180 ∘ to 360 ∘ . In this range we have found a domain of pulling angles where the spool never starts to slip independent of the strength of the pulling force. The size of the domain depends on the static friction coefficient and on the moment of inertia of the spool. The non-slipping domain is mainly formed around the critical angle where the static friction force becomes zero. For low static friction the non-slipping domain decays into two different domains. We have determined the limiting angles of the non-slipping domains and explored the transitions from a single domain to two separated domains in parameter space. (paper)

  4. Sensitivity of tsunami wave profiles and inundation simulations to earthquake slip and fault geometry for the 2011 Tohoku earthquake

    KAUST Repository

    Goda, Katsuichiro; Mai, Paul Martin; Yasuda, Tomohiro; Mori, Nobuhito

    2014-01-01

    In this study, we develop stochastic random-field slip models for the 2011 Tohoku earthquake and conduct a rigorous sensitivity analysis of tsunami hazards with respect to the uncertainty of earthquake slip and fault geometry. Synthetic earthquake slip distributions generated from the modified Mai-Beroza method captured key features of inversion-based source representations of the mega-thrust event, which were calibrated against rich geophysical observations of this event. Using original and synthesised earthquake source models (varied for strike, dip, and slip distributions), tsunami simulations were carried out and the resulting variability in tsunami hazard estimates was investigated. The results highlight significant sensitivity of the tsunami wave profiles and inundation heights to the coastal location and the slip characteristics, and indicate that earthquake slip characteristics are a major source of uncertainty in predicting tsunami risks due to future mega-thrust events.

  5. Sensitivity of tsunami wave profiles and inundation simulations to earthquake slip and fault geometry for the 2011 Tohoku earthquake

    KAUST Repository

    Goda, Katsuichiro

    2014-09-01

    In this study, we develop stochastic random-field slip models for the 2011 Tohoku earthquake and conduct a rigorous sensitivity analysis of tsunami hazards with respect to the uncertainty of earthquake slip and fault geometry. Synthetic earthquake slip distributions generated from the modified Mai-Beroza method captured key features of inversion-based source representations of the mega-thrust event, which were calibrated against rich geophysical observations of this event. Using original and synthesised earthquake source models (varied for strike, dip, and slip distributions), tsunami simulations were carried out and the resulting variability in tsunami hazard estimates was investigated. The results highlight significant sensitivity of the tsunami wave profiles and inundation heights to the coastal location and the slip characteristics, and indicate that earthquake slip characteristics are a major source of uncertainty in predicting tsunami risks due to future mega-thrust events.

  6. Structure of the la VELA Offshore Basin, Western Venezuela: AN Obliquely-Opening Rift Basin Within the South America-Caribbean Strike-Slip Plate Boundary

    Science.gov (United States)

    Blanco, J. M.; Mann, P.

    2015-12-01

    Bathymetric, gravity and magnetic maps show that the east-west trend of the Cretaceous Great Arc of the Caribbean in the Leeward Antilles islands is transected by an en echelon series of obliquely-sheared rift basins that show right-lateral offsets ranging from 20 to 40 km. The basins are 75-100 km in length and 20-30 km in width and are composed of sub-parallel, oblique slip normal faults that define deep, bathymetric channels that bound the larger islands of the Leeward Antilles including Aruba, Curacao and Bonaire. A single basin of similar orientation and structure, the Urumaco basin, is present to the southwest in the Gulf of Venezuela. We mapped structures and sedimentation in the La Vela rift basin using a 3D seismic data volume recorded down to 6 seconds TWT. The basin can be mapped from the Falcon coast where it is correlative with the right-lateral Adicora fault mapped onshore, and its submarine extension. To the southeast of the 3D survey area, previous workers have mapped a 70-km-wide zone of northeast-striking, oblique, right-lateral faults, some with apparent right-lateral offsets of the coastline. On seismic data, the faults vary in dip from 45 to 60 degrees and exhibit maximum vertical offsets of 600 m. The La Vela and other obliquely-opening rifts accommodate right-lateral shear with linkages to intervening, east-west-striking right-lateral faults like the Adicora. The zone of oblique rifts is restricted to the trend of the Great Arc of the Caribbean and may reflect the susceptiblity of this granitic basement to active shearing. The age of onset for the basins known from previous studies on the Leeward Antilles is early Miocene. As most of these faults occur offshore their potential to generate damaging earthquakes in the densely populated Leeward Antilles is not known.

  7. SAR-revealed slip partitioning on a bending fault plane for the 2014 Northern Nagano earthquake at the northern Itoigawa-Shizuoka tectonic line

    Science.gov (United States)

    Kobayashi, Tomokazu; Morishita, Yu; Yarai, Hiroshi

    2018-05-01

    By applying conventional cross-track synthetic aperture radar interferometry (InSAR) and multiple aperture InSAR techniques to ALOS-2 data acquired before and after the 2014 Northern Nagano, central Japan, earthquake, a three-dimensional ground displacement field has been successfully mapped. Crustal deformation is concentrated in and around the northern part of the Kamishiro Fault, which is the northernmost section of the Itoigawa-Shizuoka tectonic line. The full picture of the displacement field shows contraction in the northwest-southeast direction, but northeastward movement along the fault strike direction is prevalent in the northeast portion of the fault, which suggests that a strike-slip component is a significant part of the activity of this fault, in addition to a reverse faulting. Clear displacement discontinuities are recognized in the southern part of the source region, which falls just on the previously known Kamishiro Fault trace. We inverted the SAR and GNSS data to construct a slip distribution model; the preferred model of distributed slip on a two-plane fault surface shows a combination of reverse and left-lateral fault motions on a bending east-dipping fault surface with a dip of 30° in the shallow part and 50° in the deeper part. The hypocenter falls just on the estimated deeper fault plane where a left-lateral slip is inferred, whereas in the shallow part, a reverse slip is predominant, which causes surface ruptures on the ground. The slip partitioning may be accounted for by shear stress resulting from a reverse fault slip with left-lateral component at depth, for which a left-lateral slip is suppressed in the shallow part where the reverse slip is inferred. The slip distribution model with a bending fault surface, instead of a single fault plane, produces moment tensor solution with a non-double couple component, which is consistent with the seismically estimated mechanism.

  8. Complex evolution of transient slip derived from precise tremor locations in western Shikoku, Japan

    Science.gov (United States)

    Shelly, David R.; Beroza, Gregory C.; Ide, Satoshi

    2007-10-01

    Transient slip events, which occur more slowly than traditional earthquakes, are increasingly being recognized as important components of strain release on faults and may substantially impact the earthquake cycle. Surface-based geodetic instruments provide estimates of the overall slip distribution in larger transients but are unable to capture the detailed evolution of such slip, either in time or in space. Accompanying some of these slip transients is a relatively weak, extended duration seismic signal, known as nonvolcanic tremor, which has recently been shown to be generated by a sequence of shear failures occurring as part of the slip event. By precisely locating the tremor, we can track some features of slip evolution with unprecedented resolution. Here, we analyze two weeklong episodes of tremor and slow slip in western Shikoku, Japan. We find that these slip transients do not evolve in a smooth and steady fashion but contain numerous subevents of smaller size and shorter duration. In addition to along-strike migration rates of ˜10 km/d observed previously, much faster migration also occurs, usually in the slab dip direction, at rates of 25-150 km/h over distances of up to ˜20 km. We observe such migration episodes in both the updip and downdip directions. These episodes may be most common on certain portions of the plate boundary that generate strong tremor in intermittent bursts. The surrounding regions of the fault may slip more continuously, driving these stronger patches to repeated failures. Tremor activity has a strong tidal periodicity, possibly reflecting the modulation of slow slip velocity by tidal stresses.

  9. Experimental investigation of flow and slip transition in nanochannels

    Science.gov (United States)

    Li, Zhigang; Li, Long; Mo, Jingwen

    2014-11-01

    Flow slip in nanochannels is sought in many applications, such as sea water desalination and molecular separation, because it can enhance fluid transport, which is essential in nanofluidic systems. Previous findings about the slip length for simple fluids at the nanoscale appear to be controversial. Some experiments and simulations showed that the slip length is independent of shear rate, which agrees with the prediction of classic slip theories. However, there is increasing work showing that slip length is shear rate dependent. In this work, we experimentally investigate the Poiseuille flows in nanochannels. It is found that the flow rate undergoes a transition between two linear regimes as the shear rate is varied. The transition indicates that the non-slip boundary condition is valid at low shear rate. When the shear rate is larger than a critical value, slip takes place and the slip length increases linearly with increasing shear rate before approaching a constant value. The results reported in this work can help advance the understanding of flow slip in nanochannels. This work was supported by the Research Grants Council of the Hong Kong Special Administrative Region under Grant Nos. 615710 and 615312. J. Mo was partially supported by the Postgraduate Scholarship through the Energy Program at HKUST.

  10. Universal slip dynamics in metallic glasses and granular matter - linking frictional weakening with inertial effects

    Science.gov (United States)

    Denisov, Dmitry V.; Lőrincz, Kinga A.; Wright, Wendelin J.; Hufnagel, Todd C.; Nawano, Aya; Gu, Xiaojun; Uhl, Jonathan T.; Dahmen, Karin A.; Schall, Peter

    2017-03-01

    Slowly strained solids deform via intermittent slips that exhibit a material-independent critical size distribution. Here, by comparing two disparate systems - granular materials and bulk metallic glasses - we show evidence that not only the statistics of slips but also their dynamics are remarkably similar, i.e. independent of the microscopic details of the material. By resolving and comparing the full time evolution of avalanches in bulk metallic glasses and granular materials, we uncover a regime of universal deformation dynamics. We experimentally verify the predicted universal scaling functions for the dynamics of individual avalanches in both systems, and show that both the slip statistics and dynamics are independent of the scale and details of the material structure and interactions, thus settling a long-standing debate as to whether or not the claim of universality includes only the slip statistics or also the slip dynamics. The results imply that the frictional weakening in granular materials and the interplay of damping, weakening and inertial effects in bulk metallic glasses have strikingly similar effects on the slip dynamics. These results are important for transferring experimental results across scales and material structures in a single theory of deformation dynamics.

  11. Dynamic response to strike-slip tectonic control on the deposition and evolution of the Baranof Fan, Gulf of Alaska

    Science.gov (United States)

    Walton, Maureen A. L.; Gulick, Sean P. S.; Reece, Robert S.; Barth, Ginger A.; Christeson, Gail L.; VanAvendonk, Harm J.

    2014-01-01

    The Baranof Fan is one of three large deep-sea fans in the Gulf of Alaska, and is a key component in understanding large-scale erosion and sedimentation patterns for southeast Alaska and western Canada. We integrate new and existing seismic reflection profiles to provide new constraints on the Baranof Fan area, geometry, volume, and channel development. We estimate the fan’s area and total sediment volume to be ∼323,000 km2 and ∼301,000 km3, respectively, making it among the largest deep-sea fans in the world. We show that the Baranof Fan consists of channel-levee deposits from at least three distinct aggradational channel systems: the currently active Horizon and Mukluk channels, and the waning system we call the Baranof channel. The oldest sedimentary deposits are in the northern fan, and the youngest deposits at the fan’s southern extent; in addition, the channels seem to avulse southward consistently through time. We suggest that Baranof Fan sediment is sourced from the Coast Mountains in southeastern Alaska, transported offshore most recently via fjord to glacial sea valley conduits. Because of the translation of the Pacific plate northwest past sediment sources on the North American plate along the Queen Charlotte strike-slip fault, we suggest that new channel formation, channel beheadings, and southward-migrating channel avulsions have been influenced by regional tectonics. Using a simplified tectonic reconstruction assuming a constant Pacific plate motion of 4.4 cm/yr, we estimate that Baranof Fan deposition initiated ca. 7 Ma.

  12. Three-Dimensional Growth of Flexural Slip Fault-Bend and Fault-Propagation Folds and Their Geomorphic Expression

    Directory of Open Access Journals (Sweden)

    Asdrúbal Bernal

    2018-03-01

    Full Text Available The three-dimensional growth of fault-related folds is known to be an important process during the development of compressive mountain belts. However, comparatively little is known concerning the manner in which fold growth is expressed in topographic relief and local drainage networks. Here we report results from a coupled kinematic and surface process model of fault-related folding. We consider flexural slip fault-bend and fault-propagation folds that grow in both the transport and strike directions, linked to a surface process model that includes bedrock channel development and hillslope diffusion. We investigate various modes of fold growth under identical surface process conditions and critically analyse their geomorphic expression. Fold growth results in the development of steep forelimbs and gentler, wider backlimbs resulting in asymmetric drainage basin development (smaller basins on forelimbs, larger basins on backlimbs. However, topographies developed above fault-propagation folds are more symmetric than those developed above fault-bend folds as a result of their different forelimb kinematics. In addition, the surface expression of fault-bend and fault-propagation folds depends both on the slip distribution along the fault and on the style of fold growth. When along-strike plunge is a result of slip events with gently decreasing slip towards the fault tips (with or without lateral propagation, large plunge-panel drainage networks are developed at the expense of backpanel (transport-opposing and forepanel (transport-facing drainage basins. In contrast, if the fold grows as a result of slip events with similar displacements along strike, plunge-panel drainage networks are poorly developed (or are transient features of early fold growth and restricted to lateral fold terminations, particularly when the number of propagation events is small. The absence of large-scale plunge-panel drainage networks in natural examples suggests that the

  13. A flexible slip sensor using triboelectric nanogenerator approach

    Science.gov (United States)

    Wang, Xudong; Liang, Jiaming; Xiao, Yuxiang; Wu, Yichuan; Deng, Yang; Wang, Xiaohao; Zhang, Min

    2018-03-01

    With the rapid development of robotic technology, tactile sensors for robots have gained great attention from academic and industry researchers. Tactile sensors for slip detection are essential for human-like steady control in dexterous robot hand. In this paper, we propose and demonstrate a flexible slip sensor based on triboelectric nanogenerator with a seesaw structure. The sensor is composed of two porous PDMS layers separated by an inverted trapezoid structure with a height of 500 μm. In order to customize the sensitivity of the sensor, porous PDMS was fabricated by mixing PDMS with deionized water thoroughly and then removing water with heat. Laser-induced porous graphene and aluminium are served as the pair of contact materials. To detect slip from different directions, two sets of the electrode pair were used. Experimental results show a distinct difference between static state and the moment when a slip happens was detected. In addition, the output voltage of the sensors increased as the increase of slip velocity from 0.25 mm/s to 2.5 mm/s. The flexible slip sensor proposed here shows the potential applications in smart robotics and prosthesis.

  14. Influencia de un bloque rígido en un sistema de fallas de rumbo: modelamiento análogo Influence of a rigid block in a strike-slip fault system: analogue modelling

    Directory of Open Access Journals (Sweden)

    Thierry Nalpas

    2011-01-01

    Full Text Available En este trabajo se presenta un estudio de modelamiento análogo sobre la naturaleza, geometría y cinemática de la deformación a lo largo de fallas de rumbo dada la presencia de un bloque rígido en su trayectoria de deformación. Los modelos análogos están apropiadamente escalados considerando las características reológicas de los materiales que se desean contrastar en la deformación. Dos grandes parámetros fueron probados: la configuración del bloque rígido, variando su forma y tamaño, y el monto del desplazamiento. Los resultados experimentales muestran el desarrollo de rotaciones, fallas y pliegues como producto de la presencia de un bloque rígido en la trayectoria de falla. Los diversos casos geométricos probados pueden ser empleados para su comparación con sistemas de fallas de rumbo en los cuales existen diferencias litológicas de comportamiento reológico diferencial, como por ejemplo el caso del 'Núcleo rígido de Limón Verde' al sur de Chuquicamata, ubicado en la trayectoria del sistema de fallas de Domeyko.This work addresses the kinematic effects of a rigid block in strike-slip systems by using analogue models. The experiments (size, behaviour of materials were scaled down in order to represent deformation of the tested rheologic contrast conditions in deformation. Two main parameters were tested: the configuration of the rigid block, changing its form and size, and the amount of displacement. The experiments evidenced the development of rotations, faults and folds along the fault trajectory, as resulting from the presence of the rigid block during the deformation. Testing of diverse geometric situations may be used for comparison to strike-slip fault systems in which different lithologies and rheologic behaviour exist, for example, presence of the 'Limón Verde rigid core' along the Domeyko fault system, just south of Chuquicamata.

  15. Stagnation point flow and heat transfer over a nonlinear shrinking sheet with slip effects

    Directory of Open Access Journals (Sweden)

    N.F. Fauzi

    2015-12-01

    Full Text Available In this paper, an investigation is performed to analyze the effects of the slip parameters A and B on the steady stagnation-point flow and heat transfer due to a shrinking sheet in a viscous and incompressible fluid. Using similarity transformations, the governing boundary layer equations are transformed into the nonlinear ordinary (similar differential equations. The transformed equations are solved numerically using the shooting method. The dual solutions for velocity and temperature distribution exist for certain values of the positive constant velocity and temperature slip parameters. Likewise, a stability analysis has been performed to find the nature of the dual solutions. The velocity slip will delay the boundary layer separation whereas the temperature slip does not affect the boundary layer separation.

  16. Short-and-long-term Slip Rates Along the Carboneras Fault in the Betic Cordillera, Spain

    Science.gov (United States)

    Khazaradze, G.; López, R.; Pallàs, R.; Ortuño, M.; Bordonau, J.; Masana, E.

    2017-12-01

    We present the new results from our long-standing studies to understand the geodynamic behavior of the Carboneras fault, located in the SE Betic Cordilleras of Spain. Specifically, we quantify the geodetic and geologic slip rates for the onland section of the fault. As a result of our previous GPS observations, we have been able to confirm the continuing tectonic activity of the Carboneras fault: we were able to quantify that the geodetic slip rate of the fault equals 1.3±0.2 mm/yr, expressed mainly as a left-lateral strike slip motion (Echeverria et al., 2015). In autumn 2017, with the purpose of revealing a detailed nature of the crustal deformation and its partitioning between different structures, 3 new continuous GPS stations will be established along the fault-perpendicular profile. In addition, since summer 2016, we have conducted surveys of the nearby CuaTeNeo and IGN Regente campaign points. We have also established and measured several new geodetic points in the vicinity of the fault, with the aim of increasing the spatial coverage around it. The GPS measured, short-term slip rates are in surprising agreement with the estimates of the long-term, geologic slip rates based on paleoseismic studies, which indicate a minimum strike-slip rate of 1.31 mm/yr and dip-slip rate of 0.05 mm/yr since 110.3 ka (Moreno et al. 2015). In order to increase the paleoseismic event database, several new sites have been identified along the fault, where further paleoseismic trenching surveys will be performed within the coming year or two. At the site of Tostana, located at the central part of the fault, in winter 2017 seven trenches have been opened and clear evidence of past earthquakes has been encountered. These new data, combined with the findings of the recent geomorphological study of river offsets (Ferrater, 2016) and new GPS observations, should improve the reliability of the existent deformation data and therefore, will help to better understand the seismic hazard

  17. The complex evolution of transient slip revealed by precise tremor locations in western Shikoku, Japan

    Science.gov (United States)

    Shelly, D. R.; Beroza, G. C.; Ide, S.

    2007-12-01

    Transient slow slip events are increasingly being recognized as important components of strain release on faults and may substantially impact the earthquake cycle. Surface-based geodetic instruments provide estimates of the overall slip distribution in larger transients but are unable to capture the detailed evolution of such slip, either in time or space. Accompanying some of these slip transients is a relatively weak, extended duration seismic signal, known as non-volcanic tremor, which has recently been shown to be generated by a sequence of shear failures occurring as part of the slip event. By precisely locating the tremor, we can track some features of slip evolution with unprecedented resolution. Here, we analyze two weeklong episodes of tremor and slow slip in western Shikoku, Japan. We find that these slip transients do not evolve in a smooth and steady fashion but contain numerous sub-events of smaller size and shorter duration. In addition to along-strike migration rates of about 10 km/day observed previously, much faster migration also occurs, usually in the slab dip direction, at rates of 25-150 km/hour over distances of up to 20 km. We observe such migration episodes in both the up-dip and down-dip directions. These episodes may be most common on certain portions of the plate boundary that generate strong tremor in intermittent bursts. The surrounding regions of the fault may slip more continuously, driving these stronger patches to repeated failures. Tremor activity has a strong tidal periodicity, possibly reflecting the modulation of slow slip velocity by tidal stresses.

  18. Slipping slender bodies and enhanced flagellar locomotion

    Science.gov (United States)

    Man, Yi; Lauga, Eric

    2017-11-01

    In the biological world, many cells exploit slender appendages to swim, include numerous species of bacteria, algae and spermatozoa. A classical method to describe the flow field around such appendages is slender-body theory (SBT), which is often used to study flagellar motility in Newtonian fluids. However, biology environments are often rheologically complex due to the presence of polymers. These polymers generically phase-separate near rigid boundaries where low-viscosity fluid layers lead to effective slip on the surface. In this talk, we present an analytical derivation of SBT in the case where the no-slip boundary condition on the appendage is replaced by a Navier slip boundary condition. Our results demonstrate in particular a systematic reduction of the resistance coefficient of the slender filaments in their tangential direction, which leads to enhanced flagellar locomotion.

  19. Slip initiation in alternative and slip-resistant footwear.

    Science.gov (United States)

    Chander, Harish; Wade, Chip; Garner, John C; Knight, Adam C

    2017-12-01

    Slips occur as a result of failure of normal locomotion. The purpose of this study is to analyze the impact of alternative footwear (Crocs™, flip-flops) and an industry standard low-top slip-resistant shoe (SRS) under multiple gait trials (normal dry, unexpected slip, alert slip and expected slip) on lower extremity joint kinematics, kinetics and muscle activity. Eighteen healthy male participants (age: 22.28 ± 2.2 years; height: 177.66 ± 6.9 cm; mass: 79.27 ± 7.6 kg) completed the study. Kinematic, kinetic and muscle activity variables were analyzed using a 3(footwear) × 4(gait trials) repeated-measures analysis of variance at p = 0.05. Greater plantar flexion angles, lower ground reaction forces and greater muscle activity were seen on slip trials with the alternative footwear. During slip events, SRS closely resembled normal dry biomechanics, suggesting it to be a safer footwear choice compared with alternative footwear.

  20. Slip length measurement of confined air flow on three smooth surfaces.

    Science.gov (United States)

    Pan, Yunlu; Bhushan, Bharat; Maali, Abdelhamid

    2013-04-02

    An experimental measurement of the slip length of air flow close to three different solid surfaces is presented. The substrate was driven by a nanopositioner moving toward an oscillating glass sphere glued to an atomic force microscopy (AFM) cantilever. A large separation distance was used to get more effective data. The slip length value was obtained by analyzing the amplitude and phase data of the cantilever. The measurements show that the slip length does not depend on the oscillation amplitude of the cantilever. Because of the small difference among the slip lengths of the three surfaces, a simplified analysis method was used. The results show that on glass, graphite, and mica surfaces the slip lengths are 98, 234, and 110 nm, respectively.

  1. Stick-slip friction and wear of articular joints

    Science.gov (United States)

    Lee, Dong Woog; Banquy, Xavier; Israelachvili, Jacob N.

    2013-01-01

    Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps—separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints. PMID:23359687

  2. Older adults who have previously fallen due to a trip walk differently than those who have fallen due to a slip.

    Science.gov (United States)

    Wright, Rachel L; Peters, Derek M; Robinson, Paul D; Watt, Thomas N; Hollands, Mark A

    2015-01-01

    Studying the relationships between centre of mass (COM) and centre of pressure (COP) during walking has been shown to be useful in determining movement stability. The aim of the current study was to compare COM-COP separation measures during walking between groups of older adults with no history of falling, and a history of falling due to tripping or slipping. Any differences between individuals who have fallen due to a slip and those who have fallen due to a trip in measures of dynamic balance could potentially indicate differences in the mechanisms responsible for falls. Forty older adults were allocated into groups based on their self-reported fall history during walking. The non-faller group had not experienced a fall in at least the previous year. Participants who had experienced a fall were split into two groups based on whether a trip or slip resulted in the fall(s). A Vicon system was used to collect full body kinematic trajectories. Two force platforms were used to measure ground reaction forces. The COM was significantly further ahead of the COP at heel strike for the trip (14.3 ± 2.7 cm) and slip (15.3 ± 1.1 cm) groups compared to the non-fallers (12.0 ± 2.7 cm). COM was significantly further behind the COP at foot flat for the slip group (-14.9 ± 3.6 cm) compared to the non-fallers (-10.3 ± 3.9 cm). At mid-swing, the COM of the trip group was ahead of the COP (0.9 ± 1.6 cm), whereas for the slip group the COM was behind the COP (-1.2 ± 2.2 cm). These results show identifiable differences in dynamic balance control of walking between older adults with a history of tripping or slipping and non-fallers. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Analysing earthquake slip models with the spatial prediction comparison test

    KAUST Repository

    Zhang, L.; Mai, Paul Martin; Thingbaijam, Kiran Kumar; Razafindrakoto, H. N. T.; Genton, Marc G.

    2014-01-01

    Earthquake rupture models inferred from inversions of geophysical and/or geodetic data exhibit remarkable variability due to uncertainties in modelling assumptions, the use of different inversion algorithms, or variations in data selection and data processing. A robust statistical comparison of different rupture models obtained for a single earthquake is needed to quantify the intra-event variability, both for benchmark exercises and for real earthquakes. The same approach may be useful to characterize (dis-)similarities in events that are typically grouped into a common class of events (e.g. moderate-size crustal strike-slip earthquakes or tsunamigenic large subduction earthquakes). For this purpose, we examine the performance of the spatial prediction comparison test (SPCT), a statistical test developed to compare spatial (random) fields by means of a chosen loss function that describes an error relation between a 2-D field (‘model’) and a reference model. We implement and calibrate the SPCT approach for a suite of synthetic 2-D slip distributions, generated as spatial random fields with various characteristics, and then apply the method to results of a benchmark inversion exercise with known solution. We find the SPCT to be sensitive to different spatial correlations lengths, and different heterogeneity levels of the slip distributions. The SPCT approach proves to be a simple and effective tool for ranking the slip models with respect to a reference model.

  4. Analysing earthquake slip models with the spatial prediction comparison test

    KAUST Repository

    Zhang, L.

    2014-11-10

    Earthquake rupture models inferred from inversions of geophysical and/or geodetic data exhibit remarkable variability due to uncertainties in modelling assumptions, the use of different inversion algorithms, or variations in data selection and data processing. A robust statistical comparison of different rupture models obtained for a single earthquake is needed to quantify the intra-event variability, both for benchmark exercises and for real earthquakes. The same approach may be useful to characterize (dis-)similarities in events that are typically grouped into a common class of events (e.g. moderate-size crustal strike-slip earthquakes or tsunamigenic large subduction earthquakes). For this purpose, we examine the performance of the spatial prediction comparison test (SPCT), a statistical test developed to compare spatial (random) fields by means of a chosen loss function that describes an error relation between a 2-D field (‘model’) and a reference model. We implement and calibrate the SPCT approach for a suite of synthetic 2-D slip distributions, generated as spatial random fields with various characteristics, and then apply the method to results of a benchmark inversion exercise with known solution. We find the SPCT to be sensitive to different spatial correlations lengths, and different heterogeneity levels of the slip distributions. The SPCT approach proves to be a simple and effective tool for ranking the slip models with respect to a reference model.

  5. Aseismic Transform Fault Slip at the Mendocino Triple Junction From Characteristically Repeating Earthquakes

    Science.gov (United States)

    Materna, Kathryn; Taira, Taka'aki; Bürgmann, Roland

    2018-01-01

    The Mendocino Triple Junction (MTJ), at the northern terminus of the San Andreas Fault system, is an actively deforming plate boundary region with poorly constrained estimates of seismic coupling on most offshore fault surfaces. Characteristically repeating earthquakes provide spatial and temporal descriptions of aseismic creep at the MTJ, including on the oceanic transform Mendocino Fault Zone (MFZ) as it subducts beneath North America. Using a dataset of earthquakes from 2008 to 2017, we find that the easternmost segment of the MFZ displays creep during this period at about 65% of the long-term slip rate. We also find creep at slower rates on the shallower strike-slip interface between the Pacific plate and the North American accretionary wedge, as well as on a fault that accommodates Gorda subplate internal deformation. After a nearby M5.7 earthquake in 2015, we observe a possible decrease in aseismic slip on the near-shore MFZ that lasts from 2015 to at least early 2017.

  6. March separate, strike together--role of phosphorylated TAU in mitochondrial dysfunction in Alzheimer's disease.

    Science.gov (United States)

    Eckert, Anne; Nisbet, Rebecca; Grimm, Amandine; Götz, Jürgen

    2014-08-01

    The energy demand and calcium buffering requirements of the brain are met by the high number of mitochondria in neurons and in these, especially at the synapses. Mitochondria are the major producer of reactive oxygen species (ROS); at the same time, they are damaged by ROS that are induced by abnormal protein aggregates that characterize human neurodegenerative diseases such as Alzheimer's disease (AD). Because synaptic mitochondria are long-lived, any damage exerted by these aggregates impacts severely on neuronal function. Here we review how increased TAU, a defining feature of AD and related tauopathies, impairs mitochondrial function by following the principle: 'March separate, strike together!' In the presence of amyloid-β, TAU's toxicity is augmented suggesting synergistic pathomechanisms. In order to restore mitochondrial functions in neurodegeneration as a means of therapeutic intervention it will be important to integrate the various aspects of dysfunction and get a handle on targeting distinct cell types and subcellular compartments. © 2013.

  7. Heterogeneous slip and rupture models of the San Andreas fault zone based upon three-dimensional earthquake tomography

    Energy Technology Data Exchange (ETDEWEB)

    Foxall, William [Univ. of California, Berkeley, CA (United States)

    1992-11-01

    Crystal fault zones exhibit spatially heterogeneous slip behavior at all scales, slip being partitioned between stable frictional sliding, or fault creep, and unstable earthquake rupture. An understanding the mechanisms underlying slip segmentation is fundamental to research into fault dynamics and the physics of earthquake generation. This thesis investigates the influence that large-scale along-strike heterogeneity in fault zone lithology has on slip segmentation. Large-scale transitions from the stable block sliding of the Central 4D Creeping Section of the San Andreas, fault to the locked 1906 and 1857 earthquake segments takes place along the Loma Prieta and Parkfield sections of the fault, respectively, the transitions being accomplished in part by the generation of earthquakes in the magnitude range 6 (Parkfield) to 7 (Loma Prieta). Information on sub-surface lithology interpreted from the Loma Prieta and Parkfield three-dimensional crustal velocity models computed by Michelini (1991) is integrated with information on slip behavior provided by the distributions of earthquakes located using, the three-dimensional models and by surface creep data to study the relationships between large-scale lithological heterogeneity and slip segmentation along these two sections of the fault zone.

  8. Surface slip during large Owens Valley earthquakes

    KAUST Repository

    Haddon, E. K.; Amos, C. B.; Zielke, Olaf; Jayko, A. S.; Burgmann, R.

    2016-01-01

    The 1872 Owens Valley earthquake is the third largest known historical earthquake in California. Relatively sparse field data and a complex rupture trace, however, inhibited attempts to fully resolve the slip distribution and reconcile the total moment release. We present a new, comprehensive record of surface slip based on lidar and field investigation, documenting 162 new measurements of laterally and vertically displaced landforms for 1872 and prehistoric Owens Valley earthquakes. Our lidar analysis uses a newly developed analytical tool to measure fault slip based on cross-correlation of sublinear topographic features and to produce a uniquely shaped probability density function (PDF) for each measurement. Stacking PDFs along strike to form cumulative offset probability distribution plots (COPDs) highlights common values corresponding to single and multiple-event displacements. Lateral offsets for 1872 vary systematically from approximate to 1.0 to 6.0 m and average 3.31.1 m (2 sigma). Vertical offsets are predominantly east-down between approximate to 0.1 and 2.4 m, with a mean of 0.80.5 m. The average lateral-to-vertical ratio compiled at specific sites is approximate to 6:1. Summing displacements across subparallel, overlapping rupture traces implies a maximum of 7-11 m and net average of 4.41.5 m, corresponding to a geologic M-w approximate to 7.5 for the 1872 event. We attribute progressively higher-offset lateral COPD peaks at 7.12.0 m, 12.8 +/- 1.5 m, and 16.6 +/- 1.4 m to three earlier large surface ruptures. Evaluating cumulative displacements in context with previously dated landforms in Owens Valley suggests relatively modest rates of fault slip, averaging between approximate to 0.6 and 1.6 mm/yr (1 sigma) over the late Quaternary.

  9. Surface slip during large Owens Valley earthquakes

    Science.gov (United States)

    Haddon, E.K.; Amos, C.B.; Zielke, O.; Jayko, Angela S.; Burgmann, R.

    2016-01-01

    The 1872 Owens Valley earthquake is the third largest known historical earthquake in California. Relatively sparse field data and a complex rupture trace, however, inhibited attempts to fully resolve the slip distribution and reconcile the total moment release. We present a new, comprehensive record of surface slip based on lidar and field investigation, documenting 162 new measurements of laterally and vertically displaced landforms for 1872 and prehistoric Owens Valley earthquakes. Our lidar analysis uses a newly developed analytical tool to measure fault slip based on cross-correlation of sublinear topographic features and to produce a uniquely shaped probability density function (PDF) for each measurement. Stacking PDFs along strike to form cumulative offset probability distribution plots (COPDs) highlights common values corresponding to single and multiple-event displacements. Lateral offsets for 1872 vary systematically from ∼1.0 to 6.0 m and average 3.3 ± 1.1 m (2σ). Vertical offsets are predominantly east-down between ∼0.1 and 2.4 m, with a mean of 0.8 ± 0.5 m. The average lateral-to-vertical ratio compiled at specific sites is ∼6:1. Summing displacements across subparallel, overlapping rupture traces implies a maximum of 7–11 m and net average of 4.4 ± 1.5 m, corresponding to a geologic Mw ∼7.5 for the 1872 event. We attribute progressively higher-offset lateral COPD peaks at 7.1 ± 2.0 m, 12.8 ± 1.5 m, and 16.6 ± 1.4 m to three earlier large surface ruptures. Evaluating cumulative displacements in context with previously dated landforms in Owens Valley suggests relatively modest rates of fault slip, averaging between ∼0.6 and 1.6 mm/yr (1σ) over the late Quaternary.

  10. Surface slip during large Owens Valley earthquakes

    KAUST Repository

    Haddon, E. K.

    2016-01-10

    The 1872 Owens Valley earthquake is the third largest known historical earthquake in California. Relatively sparse field data and a complex rupture trace, however, inhibited attempts to fully resolve the slip distribution and reconcile the total moment release. We present a new, comprehensive record of surface slip based on lidar and field investigation, documenting 162 new measurements of laterally and vertically displaced landforms for 1872 and prehistoric Owens Valley earthquakes. Our lidar analysis uses a newly developed analytical tool to measure fault slip based on cross-correlation of sublinear topographic features and to produce a uniquely shaped probability density function (PDF) for each measurement. Stacking PDFs along strike to form cumulative offset probability distribution plots (COPDs) highlights common values corresponding to single and multiple-event displacements. Lateral offsets for 1872 vary systematically from approximate to 1.0 to 6.0 m and average 3.31.1 m (2 sigma). Vertical offsets are predominantly east-down between approximate to 0.1 and 2.4 m, with a mean of 0.80.5 m. The average lateral-to-vertical ratio compiled at specific sites is approximate to 6:1. Summing displacements across subparallel, overlapping rupture traces implies a maximum of 7-11 m and net average of 4.41.5 m, corresponding to a geologic M-w approximate to 7.5 for the 1872 event. We attribute progressively higher-offset lateral COPD peaks at 7.12.0 m, 12.8 +/- 1.5 m, and 16.6 +/- 1.4 m to three earlier large surface ruptures. Evaluating cumulative displacements in context with previously dated landforms in Owens Valley suggests relatively modest rates of fault slip, averaging between approximate to 0.6 and 1.6 mm/yr (1 sigma) over the late Quaternary.

  11. Rupture geometry and slip distribution of the 2016 January 21st Ms6.4 Menyuan, China earthquake

    Science.gov (United States)

    Zhou, Y.

    2017-12-01

    On 21 January 2016, an Ms6.4 earthquake stroke Menyuan country, Qinghai Province, China. The epicenter of the main shock and locations of its aftershocks indicate that the Menyuan earthquake occurred near the left-lateral Lenglongling fault. However, the focal mechanism suggests that the earthquake should take place on a thrust fault. In addition, field investigation indicates that the earthquake did not rupture the ground surface. Therefore, the rupture geometry is unclear as well as coseismic slip distribution. We processed two pairs of InSAR images acquired by the ESA Sentinel-1A satellite with the ISCE software, and both ascending and descending orbits were included. After subsampling the coseismic InSAR images into about 800 pixels, coseismic displacement data along LOS direction are inverted for earthquake source parameters. We employ an improved mixed linear-nonlinear Bayesian inversion method to infer fault geometric parameters, slip distribution, and the Laplacian smoothing factor simultaneously. This method incorporates a hybrid differential evolution algorithm, which is an efficient global optimization algorithm. The inversion results show that the Menyuan earthquake ruptured a blind thrust fault with a strike of 124°and a dip angle of 41°. This blind fault was never investigated before and intersects with the left-lateral Lenglongling fault, but the strikes of them are nearly parallel. The slip sense is almost pure thrusting, and there is no significant slip within 4km depth. The max slip value is up to 0.3m, and the estimated moment magnitude is Mw5.93, in agreement with the seismic inversion result. The standard error of residuals between InSAR data and model prediction is as small as 0.5cm, verifying the correctness of the inversion results.

  12. Style and rate of quaternary deformation of the Hosgri Fault Zone, offshore south-central coastal California

    Science.gov (United States)

    Hanson, Kathryn L.; Lettis, William R.; McLaren, Marcia; Savage, William U.; Hall, N. Timothy; Keller, Mararget A.

    2004-01-01

    The Hosgri Fault Zone is the southernmost component of a complex system of right-slip faults in south-central coastal California that includes the San Gregorio, Sur, and San Simeon Faults. We have characterized the contemporary style of faulting along the zone on the basis of an integrated analysis of a broad spectrum of data, including shallow high-resolution and deep penetration seismic reflection data; geologic and geomorphic data along the Hosgri and San Simeon Fault Zones and the intervening San Simeon/Hosgri pull-apart basin; the distribution and nature of near-coast seismicity; regional tectonic kinematics; and comparison of the Hosgri Fault Zone with worldwide strike-slip, oblique-slip, and reverse-slip fault zones. These data show that the modern Hosgri Fault Zone is a convergent right-slip (transpressional) fault having a late Quaternary slip rate of 1 to 3 mm/yr. Evidence supporting predominantly strike-slip deformation includes (1) a long, narrow, linear zone of faulting and associated deformation; (2) the presence of asymmetric flower structures; (3) kinematically consistent localized extensional and compressional deformation at releasing and restraining bends or steps, respectively, in the fault zone; (4) changes in the sense and magnitude of vertical separation both along trend of the fault zone and vertically within the fault zone; (5) strike-slip focal mechanisms along the fault trace; (6) a distribution of seismicity that delineates a high-angle fault extending through the seismogenic crust; (7) high ratios of lateral to vertical slip along the fault zone; and (8) the separation by the fault of two tectonic domains (offshore Santa Maria Basin, onshore Los Osos domain) that are undergoing contrasting styles of deformation and orientations of crustal shortening. The convergent component of slip is evidenced by the deformation of the early-late Pliocene unconformity. In characterizing the style of faulting along the Hosgri Fault Zone, we assessed

  13. Slip Potential of Faults in the Fort Worth Basin

    Science.gov (United States)

    Hennings, P.; Osmond, J.; Lund Snee, J. E.; Zoback, M. D.

    2017-12-01

    Similar to other areas of the southcentral United States, the Fort Worth Basin of NE Texas has experienced an increase in the rate of seismicity which has been attributed to injection of waste water in deep saline aquifers. To assess the hazard of induced seismicity in the basin we have integrated new data on location and character of previously known and unknown faults, stress state, and pore pressure to produce an assessment of fault slip potential which can be used to investigate prior and ongoing earthquake sequences and for development of mitigation strategies. We have assembled data on faults in the basin from published sources, 2D and 3D seismic data, and interpretations provided from petroleum operators to yield a 3D fault model with 292 faults ranging in strike-length from 116 to 0.4 km. The faults have mostly normal geometries, all cut the disposal intervals, and most are presumed to cut into the underlying crystalline and metamorphic basement. Analysis of outcrops along the SW flank of the basin assist with geometric characterization of the fault systems. The interpretation of stress state comes from integration of wellbore image and sonic data, reservoir stimulation data, and earthquake focal mechanisms. The orientation of SHmax is generally uniform across the basin but stress style changes from being more strike-slip in the NE part of the basin to normal faulting in the SW part. Estimates of pore pressure come from a basin-scale hydrogeologic model as history-matched to injection test data. With these deterministic inputs and appropriate ranges of uncertainty we assess the conditional probability that faults in our 3D model might slip via Mohr-Coulomb reactivation in response to increases in injected-related pore pressure. A key component of the analysis is constraining the uncertainties associated with each of the principal parameters. Many of the faults in the model are interpreted to be critically-stressed within reasonable ranges of uncertainty.

  14. Slip-stacking Dynamics for High-Power Proton Beams at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, Jeffrey Scott [Indiana Univ., Bloomington, IN (United States)

    2015-12-01

    Slip-stacking is a particle accelerator configuration used to store two particle beams with different momenta in the same ring. The two beams are longitudinally focused by two radiofrequency (RF) cavities with a small frequency difference between them. Each beam is synchronized to one RF cavity and perturbed by the other RF cavity. Fermilab uses slip-stacking in the Recycler so as to double the power of the 120 GeV proton beam in the Main Injector. This dissertation investigates the dynamics of slip-stacking beams analytically, numerically and experimentally. In the analytic analysis, I find the general trajectory of stable slip-stacking particles and identify the slip-stacking parametric resonances. In the numerical analysis, I characterize the stable phase-space area and model the particle losses. In particular, I evaluate the impact of upgrading the Fermilab Booster cycle-rate from 15 Hz to 20 Hz as part of the Proton Improvement Plan II (PIP-II). The experimental analysis is used to verify my approach to simulating slip-stacking loss. I design a study for measuring losses from the longitudinal single-particle dynamics of slip-stacking as a function of RF cavity voltage and RF frequency separation. I further propose the installation of a harmonic RF cavity and study the dynamics of this novel slip-stacking configuration. I show the harmonic RF cavity cancels out parametric resonances in slip-stacking, reduces emittance growth during slip-stacking, and dramatically enhances the stable phase-space area. The harmonic cavity is expected to reduce slip-stacking losses to far exceed PIP-II requirements. These results raise the possibility of extending slip-stacking beyond the PIP-II era.

  15. Mixed linear-nonlinear fault slip inversion: Bayesian inference of model, weighting, and smoothing parameters

    Science.gov (United States)

    Fukuda, J.; Johnson, K. M.

    2009-12-01

    Studies utilizing inversions of geodetic data for the spatial distribution of coseismic slip on faults typically present the result as a single fault plane and slip distribution. Commonly the geometry of the fault plane is assumed to be known a priori and the data are inverted for slip. However, sometimes there is not strong a priori information on the geometry of the fault that produced the earthquake and the data is not always strong enough to completely resolve the fault geometry. We develop a method to solve for the full posterior probability distribution of fault slip and fault geometry parameters in a Bayesian framework using Monte Carlo methods. The slip inversion problem is particularly challenging because it often involves multiple data sets with unknown relative weights (e.g. InSAR, GPS), model parameters that are related linearly (slip) and nonlinearly (fault geometry) through the theoretical model to surface observations, prior information on model parameters, and a regularization prior to stabilize the inversion. We present the theoretical framework and solution method for a Bayesian inversion that can handle all of these aspects of the problem. The method handles the mixed linear/nonlinear nature of the problem through combination of both analytical least-squares solutions and Monte Carlo methods. We first illustrate and validate the inversion scheme using synthetic data sets. We then apply the method to inversion of geodetic data from the 2003 M6.6 San Simeon, California earthquake. We show that the uncertainty in strike and dip of the fault plane is over 20 degrees. We characterize the uncertainty in the slip estimate with a volume around the mean fault solution in which the slip most likely occurred. Slip likely occurred somewhere in a volume that extends 5-10 km in either direction normal to the fault plane. We implement slip inversions with both traditional, kinematic smoothing constraints on slip and a simple physical condition of uniform stress

  16. Refining fault slip rates using multiple displaced terrace risers-An example from the Honey Lake fault, NE California, USA

    Science.gov (United States)

    Gold, Ryan D.; Briggs, Richard W.; Crone, Anthony J.; DuRoss, Christopher B.

    2017-11-01

    Faulted terrace risers are semi-planar features commonly used to constrain Quaternary slip rates along strike-slip faults. These landforms are difficult to date directly and therefore their ages are commonly bracketed by age estimates of the adjacent upper and lower terrace surfaces. However, substantial differences in the ages of the upper and lower terrace surfaces (a factor of 2.4 difference observed globally) produce large uncertainties in the slip-rate estimate. In this investigation, we explore how the full range of displacements and bounding ages from multiple faulted terrace risers can be combined to yield a more accurate fault slip rate. We use 0.25-m cell size digital terrain models derived from airborne lidar data to analyze three sites where terrace risers are offset right-laterally by the Honey Lake fault in NE California, USA. We use ages for locally extensive subhorizontal surfaces to bracket the time of riser formation: an upper surface is the bed of abandoned Lake Lahontan having an age of 15.8 ± 0.6 ka and a lower surface is a fluvial terrace abandoned at 4.7 ± 0.1 ka. We estimate lateral offsets of the risers ranging between 6.6 and 28.3 m (median values), a greater than fourfold difference in values. The amount of offset corresponds to the riser's position relative to modern stream meanders: the smallest offset is in a meander cutbank position, whereas the larger offsets are in straight channel or meander point-bar positions. Taken in isolation, the individual terrace-riser offsets yield slip rates ranging from 0.3 to 7.1 mm/a. However, when the offset values are collectively assessed in a probabilistic framework, we find that a uniform (linear) slip rate of 1.6 mm/a (1.4-1.9 mm/a at 95% confidence) can satisfy the data, within their respective uncertainties. This investigation demonstrates that integrating observations of multiple offset elements (crest, midpoint, and base) from numerous faulted and dated terrace risers at closely spaced

  17. Refining fault slip rates using multiple displaced terrace risers—An example from the Honey Lake fault, NE California, USA

    Science.gov (United States)

    Gold, Ryan D.; Briggs, Richard; Crone, Anthony J.; Duross, Christopher

    2017-01-01

    Faulted terrace risers are semi-planar features commonly used to constrain Quaternary slip rates along strike-slip faults. These landforms are difficult to date directly and therefore their ages are commonly bracketed by age estimates of the adjacent upper and lower terrace surfaces. However, substantial differences in the ages of the upper and lower terrace surfaces (a factor of 2.4 difference observed globally) produce large uncertainties in the slip-rate estimate. In this investigation, we explore how the full range of displacements and bounding ages from multiple faulted terrace risers can be combined to yield a more accurate fault slip rate. We use 0.25-m cell size digital terrain models derived from airborne lidar data to analyze three sites where terrace risers are offset right-laterally by the Honey Lake fault in NE California, USA. We use ages for locally extensive subhorizontal surfaces to bracket the time of riser formation: an upper surface is the bed of abandoned Lake Lahontan having an age of 15.8 ± 0.6 ka and a lower surface is a fluvial terrace abandoned at 4.7 ± 0.1 ka. We estimate lateral offsets of the risers ranging between 6.6 and 28.3 m (median values), a greater than fourfold difference in values. The amount of offset corresponds to the riser's position relative to modern stream meanders: the smallest offset is in a meander cutbank position, whereas the larger offsets are in straight channel or meander point-bar positions. Taken in isolation, the individual terrace-riser offsets yield slip rates ranging from 0.3 to 7.1 mm/a. However, when the offset values are collectively assessed in a probabilistic framework, we find that a uniform (linear) slip rate of 1.6 mm/a (1.4–1.9 mm/a at 95% confidence) can satisfy the data, within their respective uncertainties. This investigation demonstrates that integrating observations of multiple offset elements (crest, midpoint, and base) from numerous faulted and dated terrace risers at closely spaced

  18. Along-strike variations in fault frictional properties along the San Andreas Fault near Cholame, California from joint earthquake and low-frequency earthquake relocations

    Science.gov (United States)

    Harrington, Rebecca M.; Cochran, Elizabeth S.; Griffiths, Emily M.; Zeng, Xiangfang; Thurber, Clifford H.

    2016-01-01

    Recent observations of low‐frequency earthquakes (LFEs) and tectonic tremor along the Parkfield–Cholame segment of the San Andreas fault suggest slow‐slip earthquakes occur in a transition zone between the shallow fault, which accommodates slip by a combination of aseismic creep and earthquakes (fault, which accommodates slip by stable sliding (>35  km depth). However, the spatial relationship between shallow earthquakes and LFEs remains unclear. Here, we present precise relocations of 34 earthquakes and 34 LFEs recorded during a temporary deployment of 13 broadband seismic stations from May 2010 to July 2011. We use the temporary array waveform data, along with data from permanent seismic stations and a new high‐resolution 3D velocity model, to illuminate the fine‐scale details of the seismicity distribution near Cholame and the relation to the distribution of LFEs. The depth of the boundary between earthquakes and LFE hypocenters changes along strike and roughly follows the 350°C isotherm, suggesting frictional behavior may be, in part, thermally controlled. We observe no overlap in the depth of earthquakes and LFEs, with an ∼5  km separation between the deepest earthquakes and shallowest LFEs. In addition, clustering in the relocated seismicity near the 2004 Mw 6.0 Parkfield earthquake hypocenter and near the northern boundary of the 1857 Mw 7.8 Fort Tejon rupture may highlight areas of frictional heterogeneities on the fault where earthquakes tend to nucleate.

  19. Seismically-triggered soft-sediment deformation structures close to a major strike-slip fault system in the Eastern Alps (Hirlatz cave, Austria)

    Science.gov (United States)

    Salomon, Martina Lan; Grasemann, Bernhard; Plan, Lukas; Gier, Susanne; Schöpfer, Martin P. J.

    2018-05-01

    We investigate episodic soft-sediment deformation structures cross-cut by normal faults preserved in unlithified finely laminated calcite rich sediments in the Hirlatz cave in the Northern Calcareous Alps (Austria). These sediments comprise varve-like alternations of brighter carbonate/quartz rich layers, and darker clay mineral rich layers. The deformed sediments contain abundant millimeter to centimeter-scale soft-sediment structures (load casts, ball-and-pillow structures), sheet slumps (thrust faults and folds), erosive channels filled with slides and chaotic slumps. After deposition and soft-sediment deformation normal faults developed within the entire sedimentary succession, an event that probably correlates with an offset of c. 10 cm of the passage wall above the outcrop. Our major conclusions are: (i) The sediments have a glacial origin and were deposited in the Hirlatz cave under phreatic fluvio-lacustrine conditions. The deposition and the soft-sediment deformation occurred most likely during the last glaciation (i.e. around 25 ka ago); (ii) The liquefaction and formation of the soft-sediment structures in water-saturated stratified layers was triggered by episodic seismic events; (iii) The internally deformed sediments were later displaced by normal faults; (iv) A possible source for the seismic events is the active sinistral Salzach-Ennstal-Mariazeller-Puchberger (SEMP) strike-slip fault which is located about 10 km south of the outcrop and plays a major role in accommodating the extrusion of the Eastern Alps towards the Pannonian Basin. To our knowledge, the described structures are the first report of liquefaction and seismically induced soft-sediment deformations in Quaternary sediments in the Eastern Alps.

  20. Slip cast coating of alumina crucibles

    International Nuclear Information System (INIS)

    Haroun, N.A.; El-Masry, M.A.A.

    1980-01-01

    The development of a process for coating alumina crucibles with MgO protective coat in a two-step slip casting operation is described. The best milling conditions for the alumina used were wet ball milling for 24 hr. MgO had to be calcined at 1200 0 C to minimize hydration. Optimum slip casting conditions for alumina and magnesia were found to be L/S I and pH 3-6 or 9-II for the former, and L/S 3 (alcohol) and pH 8.5-10 for the latter. Sintering of Al 2 O 3 and MgO in the temperature range 1150-500 0 C was investigated. Additions of NiO and MgO lowered the sintered densities at lower temperatures but improved the densification at 1500 0 C. Near theoretical density Al 2 O 3 and MgO crucibles were obtained. A two-step slip casting technique was developed to coat Al 2 O 3 with MgO. Certain slow firing schedules could eliminate the otherwise observed coat-crucible separation and cracks. (author)

  1. Areas prone to slow slip events impede earthquake rupture propagation and promote afterslip

    Science.gov (United States)

    Rolandone, Frederique; Nocquet, Jean-Mathieu; Mothes, Patricia A.; Jarrin, Paul; Vallée, Martin; Cubas, Nadaya; Hernandez, Stephen; Plain, Morgan; Vaca, Sandro; Font, Yvonne

    2018-01-01

    At subduction zones, transient aseismic slip occurs either as afterslip following a large earthquake or as episodic slow slip events during the interseismic period. Afterslip and slow slip events are usually considered as distinct processes occurring on separate fault areas governed by different frictional properties. Continuous GPS (Global Positioning System) measurements following the 2016 Mw (moment magnitude) 7.8 Ecuador earthquake reveal that large and rapid afterslip developed at discrete areas of the megathrust that had previously hosted slow slip events. Regardless of whether they were locked or not before the earthquake, these areas appear to persistently release stress by aseismic slip throughout the earthquake cycle and outline the seismic rupture, an observation potentially leading to a better anticipation of future large earthquakes. PMID:29404404

  2. Effect of basement structure and salt tectonics on deformation styles along strike: An example from the Kuqa fold-thrust belt, West China

    Science.gov (United States)

    Neng, Yuan; Xie, Huiwen; Yin, Hongwei; Li, Yong; Wang, Wei

    2018-04-01

    The Kuqa fold-thrust belt (KFTB) has a complex thrust-system geometry and comprises basement-involved thrusts, décollement thrusts, triangle zones, strike-slip faults, transpressional faults, and pop-up structures. These structures, combined with the effects of Paleogene salt tectonics and Paleozoic basement uplift form a complex structural zone trending E-W. Interpretation and comprehensive analysis of recent high-quality seismic data, field observations, boreholes, and gravity data covering the KFTB has been performed to understand the characteristics and mechanisms of the deformation styles along strike. Regional sections, fold-thrust system maps of the surface and the sub-salt layer, salt and basement structure distribution maps have been created, and a comprehensive analysis of thrust systems performed. The results indicate that the thrust-fold system in Paleogene salt range can be divided into five segments from east to west: the Kela-3, Keshen, Dabei, Bozi, and Awate segments. In the easternmost and westernmost parts of the Paleogene salt range, strike-slip faulting and basement-involved thrusting are the dominant deformation styles, as basement uplift and the limits of the Cenozoic evaporite deposit are the main controls on deformation. Salt-core detachment fold-thrust systems coincide with areas of salt tectonics, and pop-up, imbricate, and duplex structures are associated with the main thrust faults in the sub-salt layer. Distribution maps of thrust systems, basement structures, and salt tectonics show that Paleozoic basement uplift controlled the Paleozoic foreland basin morphology and the distribution of Cenozoic salt in the KFTB, and thus had a strong influence on the segmented structural deformation and evolution of the fold-thrust belt. Three types of transfer zone are identified, based on the characteristics of the salt layer and basement uplift, and the effects of these zones on the fault systems are evaluated. Basement uplift and the boundary of

  3. Southeastward increase of the late Quaternary slip-rate of the Xianshuihe fault, eastern Tibet. Geodynamic and seismic hazard implications

    Science.gov (United States)

    Bai, Mingkun; Chevalier, Marie-Luce; Pan, Jiawei; Replumaz, Anne; Leloup, Philippe Hervé; Métois, Marianne; Li, Haibing

    2018-03-01

    The left-lateral strike-slip Xianshuihe fault system located in the eastern Tibetan Plateau is considered as one of the most tectonically active intra-continental fault system in China, along which more than 20 M > 6.5 and more than 10 M > 7 earthquakes occurred since 1700. Therefore, studying its activity, especially its slip rate at different time scales, is essential to evaluate the regional earthquake hazard. Here, we focus on the central segment of the Xianshuihe fault system, where the Xianshuihe fault near Kangding city splays into three branches: the Selaha, Yalahe and Zheduotang faults. In this paper we use precise dating together with precise field measurements of offsets to re-estimate the slip rate of the fault that was suggested without precise age constraints. We studied three sites where the active Selaha fault cuts and left-laterally offsets moraine crests and levees. We measured horizontal offsets of 96 ± 20 m at Tagong levees (TG), 240 ± 15 m at Selaha moraine (SLH) and 80 ± 5 m at Yangjiagou moraine (YJG). Using 10Be cosmogenic dating, we determined abandonment ages at Tagong, Selaha and Yangjiagou of 12.5 (+ 2.5 / - 2.2) ka, 22 ± 2 ka, and 18 ± 2 ka, respectively. By matching the emplacement age of the moraines or levees with their offsets, we obtain late Quaternary horizontal average slip-rates of 7.6 (+ 2.3 / - 1.9) mm/yr at TG and 10.7 (+ 1.3 / - 1.1) mm/yr at SLH, i.e., 5.7-12 mm/yr or between 9.6 and 9.9 mm/yr assuming that the slip rate should be constant between the nearby TG and SLH sites. At YJG, we obtain a lower slip rate of 4.4 ± 0.5 mm/yr, most likely because the parallel Zheduotang fault shares the slip rate at this longitude, therefore suggesting a ∼5 mm/yr slip rate along the Zheduotang fault. The ∼10 mm/yr late Quaternary rate along the Xianshuihe fault is higher than that along the Ganzi fault to the NW (6-8 mm/yr). This appears to be linked to the existence of the Longriba fault system that separates the Longmenshan

  4. A new estimate for present-day Cocos-Caribbean Plate motion: Implications for slip along the Central American Volcanic Arc

    Science.gov (United States)

    DeMets, Charles

    Velocities from 153 continuously-operating GPS sites on the Caribbean, North American, and Pacific plates are combined with 61 newly estimated Pacific-Cocos seafloor spreading rates and additional marine geophysical data to derive a new estimate of present-day Cocos-Caribbean plate motion. A comparison of the predicted Cocos-Caribbean direction to slip directions of numerous shallow-thrust subduction earthquakes from the Middle America trench between Costa Rica and Guatemala shows the slip directions to be deflected 10° clockwise from the plate convergence direction, supporting the hypothesis that frequent dextral strike-slip earthquakes along the Central American volcanic arc result from partitioning of oblique Cocos-Caribbean plate convergence. Linear velocity analysis for forearc locations in Nicaragua and Guatemala predicts 14±2 mm yr-1 of northwestward trench-parallel slip of the forearc relative to the Caribbean plate, possibly decreasing in magnitude in El Salvador and Guatemala, where extension east of the volcanic arc complicates the tectonic setting.

  5. Slow Earthquake Hunters: A New Citizen Science Project to Identify and Catalog Slow Slip Events in Geodetic Data

    Science.gov (United States)

    Bartlow, N. M.

    2017-12-01

    Slow Earthquake Hunters is a new citizen science project to detect, catalog, and monitor slow slip events. Slow slip events, also called "slow earthquakes", occur when faults slip too slowly to generate significant seismic radiation. They typically take between a few days and over a year to occur, and are most often found on subduction zone plate interfaces. While not dangerous in and of themselves, recent evidence suggests that monitoring slow slip events is important for earthquake hazards, as slow slip events have been known to trigger damaging "regular" earthquakes. Slow slip events, because they do not radiate seismically, are detected with a variety of methods, most commonly continuous geodetic Global Positioning System (GPS) stations. There is now a wealth of GPS data in some regions that experience slow slip events, but a reliable automated method to detect them in GPS data remains elusive. This project aims to recruit human users to view GPS time series data, with some post-processing to highlight slow slip signals, and flag slow slip events for further analysis by the scientific team. Slow Earthquake Hunters will begin with data from the Cascadia subduction zone, where geodetically detectable slow slip events with a duration of at least a few days recur at regular intervals. The project will then expand to other areas with slow slip events or other transient geodetic signals, including other subduction zones, and areas with strike-slip faults. This project has not yet rolled out to the public, and is in a beta testing phase. This presentation will show results from an initial pilot group of student participants at the University of Missouri, and solicit feedback for the future of Slow Earthquake Hunters.

  6. Pore Pressure Evolution in Shallow Subduction Earthquake Sequences and Effects on Aseismic Slip Transients -- Numerical Modeling With Rate and State Friction

    Science.gov (United States)

    Liu, Y.; Rice, J. R.

    2005-12-01

    In 3D modeling of long tectonic loading and earthquake sequences on a shallow subduction fault [Liu and Rice, 2005], with depth-variable rate and state friction properties, we found that aseismic transient slip episodes emerge spontaneously with only a simplified representation of effects of metamorphic fluid release. That involved assumption of a constant in time but uniformly low effective normal stress in the downdip region. As suggested by observations in several major subduction zones [Obara, 2002; Rogers and Dragert, 2003; Kodaira et al, 2004], the presence of fluids, possibly released from dehydration reactions beneath the seismogenic zone, and their pressurization within the fault zone may play an important role in causing aseismic transients and associated non-volcanic tremors. To investigate the effects of fluids in the subduction zone, particularly on the generation of aseismic transients and their various features, we develop a more complete physical description of the pore pressure evolution (specifically, pore pressure increase due to supply from dehydration reactions and shear heating, decrease due to transport and dilatancy during slip), and incorporate that into the rate and state based 3D modeling. We first incorporated two important factors, dilatancy and shear heating, following Segall and Rice [1995, 2004] and Taylor [1998]. In the 2D simulations (slip varies with depth only), a dilatancy-stabilizing effect is seen which slows down the seismic rupture front and can prevent rapid slip from extending all the way to the trench, similarly to Taylor [1998]. Shear heating increases the pore pressure, and results in faster coseismic rupture propagation and larger final slips. In the 3D simulations, dilatancy also stabilizes the along-strike rupture propagation of both seismic and aseismic slips. That is, aseismic slip transients migrate along the strike faster with a shorter Tp (the characteristic time for pore pressure in the fault core to re

  7. Constant Fault Slip-Rates Over Hundreds of Millenia Constrained By Deformed Quaternary Palaeoshorelines: the Vibo and Capo D'Orlando Faults, Southern Italy.

    Science.gov (United States)

    Meschis, M.; Roberts, G.; Robertson, J.; Houghton, S.; Briant, R. M.

    2017-12-01

    Whether slip-rates on active faults accumulated over multiple seismic events is constant or varying over tens to hundreds of millenia timescales is an open question that can be addressed through study of deformed Quaternary palaeoshorelines. It is important to know the answer so that one can judge whether shorter timescale measurements (e.g. Holocene palaeoseismology or decadal geodesy) are suitable for determining earthquake recurrence intervals for Probabilistic Seismic Hazard Assessment or more suitable for studying temporal earthquake clustering. We present results from the Vibo Fault and the Capo D'Orlando Fault, that lie within the deforming Calabrian Arc, which has experienced damaging seismic events such as the 1908 Messina Strait earthquake ( Mw 7) and the 1905 Capo Vaticano earthquake ( Mw 7). These normal faults deform uplifted Late Quaternary palaeoshorelines, which outcrop mainly within their hangingwalls, but also partially in their footwalls, showing that a regional subduction and mantle-related uplift outpaces local fault-related subsidence. Through (1) field and DEM-based mapping of palaeoshorelines, both up flights of successively higher, older inner edges, and along the strike of the faults, and (2) utilisation of synchronous correlation of non-uniformly-spaced inner edge elevations with non-uniformly spaced sea-level highstand ages, we show that slip-rates decrease towards fault tips and that slip-rates have remained constant since 340 ka (given the time resolution we obtain). The slip-rates for the Capo D'Orlando Fault and Vibo Fault are 0.61mm/yr and 1mm/yr respectively. We show that the along-strike gradients in slip-rate towards fault tips differ for the two faults hinting at fault interaction and also discuss this in terms of other regions of extension like the Gulf of Corinth, Greece, where slip-rate has been shown to change through time through the Quaternary. We make the point that slip-rates may change through time as fault systems grow

  8. SLOW SLIP EVENTS: PARAMETERS, CONDITIONS OF OCCURRENCE, AND FUTURE RESEARCH PROSPECTS

    Directory of Open Access Journals (Sweden)

    G. G. Kocharyan

    2014-01-01

    propagation along the fault strike are variable from a few hundred metres to 20–30 km/day. Slip velocities tend to decrease with scale (Fig. 7.Various slip modes were realized in laboratory experiments with slider model. Main specific features of slow slip along faults were simulated in the laboratory conditions. Possibilities for implementation of different deformation regimes were mainly determined by structure of simulated fault gouge. At equal Coulombic strength, small variations of structural characteristics, such as granulometric composition, grain shape, presence of fluid and its viscosity, may critically impact the deformation mode (Fig. 12.As evidenced by the data consolidated and analysed in this article, conditionally stable regimes of deformation of crustal discontinuities are a common phenomenon. Studies of such transitional deformation regimes seem promising for establishment of regularities in generation and evolution of dynamic events, such earthquakes, tectonic rock bursts, and slope events.

  9. ["Bell-striking" Saying of Acupuncture Therapy].

    Science.gov (United States)

    Zhao, Jing-Sheng

    2017-04-25

    As an analogy, a prototype of "bell-striking" is proposed in the present paper for exploring the basic properties, major elements, and potential mechanisms of acupuncture stimulation. On the strength of analysis on the physiological basis of acupuncture effect, several fundamental aspects of acupuncture are summarized as a) the body-surface stimulating characters, b) general and local effects, and c) triggering the auto-regulative function of the organism, which mimics the "bell-striking" response. Namely, when stroke, bell will chime, otherwise, chiming will not be heard. During analyzing special contents of acupuncture theory, its formative background should not be separated, and it is improper to take, modern medical theory of the human body as the guiding thinking way for researching the ancient Chinese medical literature.

  10. Excitation of tsunami by a pure strike-slip earthquake. ; Izu Oshima kinkai earthquake tsunami on Feb. 20, 1990. Yokozure danso jishin ni yoru tsunami no reiki. ; 1990 nen 2 gatsu 20 nichi Izu Oshima kinkai jishin tsunami

    Energy Technology Data Exchange (ETDEWEB)

    Abe, K. (Nippon Dental University, Tokyo (Japan). Niigata Junior College); Okada, M. (Meteorological Research Institute, Tsukuba (Japan))

    1993-06-24

    A numerical experiment was performed to reproduce the tsunami from the Izu-Oshima Kinkai Earthquake which occurred on February 20, 1990, using a tsunami excited by a pure strike-slip fault. An existence of a vertical fault with a length of 15 km and a width of 12 km was hypothesized in the south-north direction on the ocean bottom around the focal region. Then, a tsunami was assumed to have been excited when the fault was given a side-slip movement to create discrepancies of 1 m in the fault. Water level change for one hour after onset of the tsunami was calculated in one-second interval in each unit square with a side length of 1 km over an ocean area of 200 km from east to west and 150 km from north to south centering on the wave source. The results obtained from the calculation were harmonious with tsunami waveforms observed at five stations in the subject region and their spectral analytic results. Reproduced were the two predominant frequencies commonly observed at more than two stations, and difference in predominant cycles that appear according to azimuths of the observation points to the epicenter. These facts endorse the reasonability of the above hypothesis. 9 refs., 11 figs.

  11. Slip in the 2010-2011 Canterbury Earthquakes, New Zealand and implications for future seismic hazard in Christchurch

    Science.gov (United States)

    Elliott, J. R.; Nissen, E.; England, P. C.; Jackson, J. A.; Lamb, S.; Li, Z.; Oehlers, M.; Parsons, B. E.

    2011-12-01

    The September 2010 Mw 7.1 Darfield and February 2011 Mw 6.3 Christchurch (New Zealand) earthquakes occurred on previously unknown faults. We use InSAR, field mapping, aerial photographs, high-resolution satellite imagery, a LiDAR DEM, SAR amplitude offsets and teleseismic body-wave modelling to constrain the pattern of faulting in these earthquakes. The InSAR phase measurement revealed a complex pattern of ground deformation, and the fault source geometry and slip model was difficult to constrain with this data set alone. By combining the fault rupture from field observations and measured offset roads and hedges in the satellite/aerial imagery, we were able to reduce the number of free parameters in our fault model. The fault model obtained using these constraints revealed slip on multiple strike-slip segments and secondary thrust faults associated with the Darfield mainshock. The main fault rupture is about 45 km long, and is confined largely to the upper 10 km of the crust. Slip on the individual fault segments of up to 8 m at 4 km depth indicates large stress drops of about 10 MPa, which may imply an immature fault rather than rupture on an established fault. We find good agreement between horizontal offsets and slip vectors determined in the field with those derived from the remote aerial and satellite imagery. We also find good agreement between the predicted surface slip from the InSAR-derived fault model and these offsets. LiDAR determined vertical offsets of 0.1-1.4 m are consistent with the small dip-slip values predicted in the InSAR model. The orientations of the P-axes for the reverse and strike-slip segments are consistent with those expected from the GPS-derived strain field which shows a principal contraction direction ENE-WSW (Wallace et al., 2007). However, the absence of any geomorphic indicators for previous large earthquakes, obscured by the gravels of the Canterbury Plain, led to the notion that the Christchurch area was in the interior of a

  12. Effective slip lengths for flows over surfaces with nanobubbles: the effects of finite slip

    International Nuclear Information System (INIS)

    Hendy, S C; Lund, N J

    2009-01-01

    We consider effective slip lengths for flows of simple liquids over surfaces contaminated by gaseous nanobubbles. In particular, we examine whether the effects of finite slip over the liquid-bubble interface are important in limiting effective slip lengths over such surfaces. Using an expression that interpolates between the perfect slip and finite slip regimes for flow over bubbles, we conclude that for the bubble dimensions and coverages typically reported in the literature the effects of finite slip are secondary, reducing effective slip lengths by only 10%. Further, we find that nanobubbles do not significantly increase slip lengths beyond those reported for bare hydrophobic surfaces.

  13. New geologic slip rates for the Agua Blanca Fault, northern Baja California, Mexico

    Science.gov (United States)

    Gold, P. O.; Behr, W. M.; Fletcher, J. M.; Hinojosa-Corona, A.; Rockwell, T. K.

    2015-12-01

    Within the southern San Andreas transform plate boundary system, relatively little is known regarding active faulting in northern Baja California, Mexico, or offshore along the Inner Continental Borderland. The inner offshore system appears to be fed from the south by the Agua Blanca Fault (ABF), which strikes northwest across the Peninsular Ranges of northern Baja California. Therefore, the geologic slip rate for the ABF also provides a minimum slip rate estimate for the offshore system, which is connected to the north to faults in the Los Angeles region. Previous studies along the ABF determined slip rates of ~4-6 mm/yr (~10% of relative plate motion). However, these rates relied on imprecise age estimates and offset geomorphic features of a type that require these rates to be interpreted as minima, allowing for the possibility that the slip rate for the ABF may be greater. Although seismically quiescent, the surface trace of the ABF clearly reflects Holocene activity, and given its connectivity with the offshore fault system, more quantitative slip rates for the ABF are needed to better understand earthquake hazard for both US and Mexican coastal populations. Using newly acquired airborne LiDAR, we have mapped primary and secondary fault strands along the segmented western 70 km of the ABF. Minimal development has left the geomorphic record of surface slip remarkably well preserved, and we have identified abundant evidence meter to km scale right-lateral displacement, including new Late Quaternary slip rate sites. We verified potential reconstructions at each site during summer 2015 fieldwork, and selected an initial group of three high potential slip rate sites for detailed mapping and geochronologic analyses. Offset landforms, including fluvial terrace risers, alluvial fans, and incised channel fill deposits, record displacements of ~5-80 m, and based on minimal soil development, none appear older than early Holocene. To quantitatively constrain landform ages

  14. Coseismic slip in the 2010 Yushu earthquake (China, constrained by wide-swath and strip-map InSAR

    Directory of Open Access Journals (Sweden)

    Y. Wen

    2013-01-01

    Full Text Available On 14 April 2010, an Mw = 6.9 earthquake occurred in the Yushu county of China, which caused ~3000 people to lose their lives. Integrated with the information from the observed surface ruptures and aftershock locations, the faulting pattern of this earthquake is derived from the descending wide-swath and ascending strip mode PALSAR data collected by ALOS satellite. We used a layered crustal model and stress drop smoothing constraint to infer the coseismic slip distribution. Our model suggests that the earthquake fault can be divided into four segments and the slip mainly occurs within the upper 12 km with a maximum slip of 2.0 m at depth of 3 km on the Jiegu segment. The rupture of the upper 12 km is dominated by left-lateral strike-slip motion. The relatively small slip along the SE region of Yushu segment suggests a slip deficit there. The inverted geodetic moment is approximately Mw = 6.9, consistent with the seismological results. The average stress drop caused by the earthquake is about 2 MPa with a maximum stress drop of 8.3 MPa. Furthermore, the calculated static Coulomb stress changes in surrounding regions show increased Coulomb stress occurred in the SE region along the Yushu segment but with less aftershock, indicating an increased seismic hazard in this region after the earthquake.

  15. Analytical solutions for squeeze flow with partial wall slip

    DEFF Research Database (Denmark)

    Laun, HM; Rady, M; Hassager, Ole

    1999-01-01

    , respectively. The slip velocity at the plate increases linearly with the radius up to the rim slip velocity upsilon(s). For small Saps H, the resulting apparent Newtonian rim shear rate-measured for a constant rim shear stress, i.e. an imposed force increasing proportional to 1/H-yields a straight line...... if plotted versus 1/H. The slope of the straight line is equal to 6 upsilon(s) whereas the intersect with the ordinate yields the effective Newtonian rim shear rate to be converted into the true rim shear rate by means of the power law exponent. The advantage of the new technique is the separation of bulk...

  16. A Wideband Magnetoresistive Sensor for Monitoring Dynamic Fault Slip in Laboratory Fault Friction Experiments.

    Science.gov (United States)

    Kilgore, Brian D

    2017-12-02

    A non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments employs an inexpensive magnetoresistive sensor, a small neodymium rare earth magnet, and user built application-specific wideband signal conditioning. The magnetoresistive sensor generates a voltage proportional to the changing angles of magnetic flux lines, generated by differential motion or rotation of the near-by magnet, through the sensor. The performance of an array of these sensors compares favorably to other conventional position sensing methods employed at multiple locations along a 2 m long × 0.4 m deep laboratory strike-slip fault. For these magnetoresistive sensors, the lack of resonance signals commonly encountered with cantilever-type position sensor mounting, the wide band response (DC to ≈ 100 kHz) that exceeds the capabilities of many traditional position sensors, and the small space required on the sample, make them attractive options for capturing high speed fault slip measurements in these laboratory experiments. An unanticipated observation of this study is the apparent sensitivity of this sensor to high frequency electomagnetic signals associated with fault rupture and (or) rupture propagation, which may offer new insights into the physics of earthquake faulting.

  17. A Kinematic Model of Slow Slip Constrained by Tremor-Derived Slip Histories in Cascadia

    Science.gov (United States)

    Schmidt, D. A.; Houston, H.

    2016-12-01

    We explore new ways to constrain the kinematic slip distributions for large slow slip events using constraints from tremor. Our goal is to prescribe one or more slip pulses that propagate across the fault and scale appropriately to satisfy the observations. Recent work (Houston, 2015) inferred a crude representative stress time history at an average point using the tidal stress history, the static stress drop, and the timing of the evolution of tidal sensitivity of tremor over several days of slip. To convert a stress time history into a slip time history, we use simulations to explore the stressing history of a small locked patch due to an approaching rupture front. We assume that the locked patch releases strain through a series of tremor bursts whose activity rate is related to the stressing history. To test whether the functional form of a slip pulse is reasonable, we assume a hypothetical slip time history (Ohnaka pulse) timed with the occurrence of tremor to create a rupture front that propagates along the fault. The duration of the rupture front for a fault patch is constrained by the observed tremor catalog for the 2010 ETS event. The slip amplitude is scaled appropriately to match the observed surface displacements from GPS. Through a forward simulation, we evaluate the ability of the tremor-derived slip history to accurately predict the pattern of surface displacements observed by GPS. We find that the temporal progression of surface displacements are well modeled by a 2-4 day slip pulse, suggesting that some of the longer duration of slip typically found in time-dependent GPS inversions is biased by the temporal smoothing. However, at some locations on the fault, the tremor lingers beyond the passage of the slip pulse. A small percentage (5-10%) of the tremor appears to be activated ahead of the approaching slip pulse, and tremor asperities experience a driving stress on the order of 10 kPa/day. Tremor amplitude, rather than just tremor counts, is needed

  18. Limits of recovery against slip-induced falls while walking.

    Science.gov (United States)

    Yang, Feng; Bhatt, Tanvi; Pai, Yi-Chung

    2011-10-13

    Slip-induced falls in gait often have devastating consequences. The purposes of this study were 1) to select the determinants that can best discriminate the outcomes (recoveries or falls) of an unannounced slip induced in gait (and to find their corresponding threshold, i.e., the limits of recovery, which can clearly separate these two outcomes), and 2) to verify these results in a subset of repeated-slip trials. Based on the data collected from 69 young subjects during a slip induced in gait, nine different ways of combining the center of mass (COM) stability, the hip height, and its vertical velocity were investigated with the aid of logistic regression. The results revealed that the COM stability (s) and limb support (represented by the quotient of hip vertical velocity to hip height, S(hip)) recorded at the instant immediately prior to the recovery step touchdown were sufficiently sensitive to account for all (100%) variance in falls, and specific enough to account for nearly all (98.3%) variability in recoveries. This boundary (S(hip)=-0.22s-0.25), which quantifies the risk of falls in the stability-limb support quotient (s-S(hip)) domain, was fully verified using second-slip and third-slip trials (n=76) with classification of falls at 100% and recoveries at 98.6%. The severity of an actual fall is likely to be greater further below the boundary, while the likelihood of a fall diminishes above it. Finally, the slope of the boundary also indicates the tradeoff between the stability and limb support, whereby high stability can compensate for the insufficiency in limb support, or vice versa. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Stokes drag on a disc with a Navier slip condition near a plane wall

    International Nuclear Information System (INIS)

    Sherwood, J D

    2013-01-01

    The Stokes drag and couple acting on a disc moving through incompressible Newtonian fluid are investigated for the case when the fluid obeys a Navier slip condition, with slip length b, on the surface of the disc. The fluid is bounded by an infinite plane wall on which there is no slip. The disc, of zero thickness and radius a, is parallel to the wall and distance h from it. Analyses are presented for the limits h ≫ a and h ≪ a; results for intermediate values of the separation h are obtained numerically by means of Tranter's method. The resistance coefficients for translation normal to the disc surface, and for rotation about a diameter, are unaffected by slip when the disc lies in unbounded fluid, but all resistance coefficients depend upon the slip length b when the disc is close to the wall. Their dependence on h becomes weak when b ≫ a. (paper)

  20. Improved ceramic slip casting technique. [application to aircraft model fabrication

    Science.gov (United States)

    Buck, Gregory M. (Inventor); Vasquez, Peter (Inventor)

    1993-01-01

    A primary concern in modern fluid dynamics research is the experimental verification of computational aerothermodynamic codes. This research requires high precision and detail in the test model employed. Ceramic materials are used for these models because of their low heat conductivity and their survivability at high temperatures. To fabricate such models, slip casting techniques were developed to provide net-form, precision casting capability for high-purity ceramic materials in aqueous solutions. In previous slip casting techniques, block, or flask molds made of plaster-of-paris were used to draw liquid from the slip material. Upon setting, parts were removed from the flask mold and cured in a kiln at high temperatures. Casting detail was usually limited with this technique -- detailed parts were frequently damaged upon separation from the flask mold, as the molded parts are extremely delicate in the uncured state, and the flask mold is inflexible. Ceramic surfaces were also marred by 'parting lines' caused by mold separation. This adversely affected the aerodynamic surface quality of the model as well. (Parting lines are invariably necessary on or near the leading edges of wings, nosetips, and fins for mold separation. These areas are also critical for flow boundary layer control.) Parting agents used in the casting process also affected surface quality. These agents eventually soaked into the mold, the model, or flaked off when releasing the case model. Different materials were tried, such as oils, paraffin, and even an algae. The algae released best, but some of it remained on the model and imparted an uneven texture and discoloration on the model surface when cured. According to the present invention, a wax pattern for a shell mold is provided, and an aqueous mixture of a calcium sulfate-bonded investment material is applied as a coating to the wax pattern. The coated wax pattern is then dried, followed by curing to vaporize the wax pattern and leave a shell

  1. Slipping on pedestrian surfaces: methods for measuring and evaluating the slip resistance.

    Science.gov (United States)

    Wetzel, Christoph; Windhövel, Ulrich; Mewes, Detlef; Ceylan, Orhan

    2015-01-01

    Tripping, slipping and falling accidents are among the types of accident with a high incidence. This article describes the requirements concerning slip resistance, as well as the state of the art of slip resistance measurement standards in the European Community and the USA. The article also describes how risk assessment can be performed in the field.

  2. Determination of the Navier slip coefficient of microchannels exploiting the streaming potential.

    Science.gov (United States)

    Park, Hung Mok

    2012-03-01

    For most microchannels made of hydrophobic materials such as polymers, velocity slip occurs at the wall, affecting volumetric flow rate of electroosmotic flow Q(eof) and streaming potential (∂ϕ(str)/∂z). Since most techniques exploit Q(eof) or (∂ϕ(str)/∂z) to determine the zeta potential, ζ, it is very difficult to measure ζ of hydrophobic walls, if the slip coefficient b is not found a priori. Until now, Q(eof) and (∂ϕ(str)/∂z) are known to depend on ζ and b in a same functional form, which makes it impossible to estimate ζ or b separately using measurements of Q(eof) and (∂ϕ(str)/∂z). However, exploiting the analytic formula for Q(eof) and (∂ϕ(str)/∂z) derived in the present work, it is found that the effect of ζ and that of b on Q(eof) and (∂ϕ(str)/∂z) can be separated from each other by varying the bulk ionic concentration. Thus, the slip coefficient as well as the zeta potential of hydrophobic microchannels can be found with reasonable accuracy by means of a nonlinear curve fitting method using measured data of Q(eof) and (∂ϕ(str)/∂z) at various bulk ionic concentrations. The present method allows an accurate estimation of slip coefficient of hydrophobic microchannels, which is quite simple and cheap compared with methods employing microparticle velocimetry. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Oscillatory Stokes Flow Past a Slip Cylinder

    Science.gov (United States)

    Palaniappan, D.

    2013-11-01

    Two-dimensional transient slow viscous flow past a circular cylinder with Navier slip boundary conditions is considered in the limit of low-Reynolds number. The oscillatory Stokes flow problem around a cylinder is solved using the stream function method leading to an analytic solution in terms of modified Bessel functions of the second kind. The corresponding steady-state behavior yields the familiar paradoxical result first detected by Stokes. It is noted that the two key parameters, viz., the frequency λ, and the slip coefficient ξ have a significant impact on the flow field in the vicinity of the cylinder contour. In the limit of very low frequency, the flow is dominated by a term containing a well-known biharmonic function found by Stokes that has a singular behavior at infinity. Local streamlines for small times show interesting flow patterns. Attached eddies due to flow separation - observed in the no-slip case - either get detached or pushed away from the cylinder surface as ξ is varied. Computed asymptotic results predict that the flow exhibits inviscid behavior far away from the cylinder in the frequency range 0 < λ << 1 . Although the frequency of oscillations is finite, our exact solutions reveal fairly rapid transitions in the flow domain. Research Enhancement grant, TAMUCC.

  4. Quantifying slip balance in the earthquake cycle: Coseismic slip model constrained by interseismic coupling

    KAUST Repository

    Wang, Lifeng; Hainzl, Sebastian; Mai, Paul Martin

    2015-01-01

    The long-term slip on faults has to follow, on average, the plate motion, while slip deficit is accumulated over shorter time scales (e.g., between the large earthquakes). Accumulated slip deficits eventually have to be released by earthquakes and aseismic processes. In this study, we propose a new inversion approach for coseismic slip, taking interseismic slip deficit as prior information. We assume a linear correlation between coseismic slip and interseismic slip deficit, and invert for the coefficients that link the coseismic displacements to the required strain accumulation time and seismic release level of the earthquake. We apply our approach to the 2011 M9 Tohoku-Oki earthquake and the 2004 M6 Parkfield earthquake. Under the assumption that the largest slip almost fully releases the local strain (as indicated by borehole measurements, Lin et al., 2013), our results suggest that the strain accumulated along the Tohoku-Oki earthquake segment has been almost fully released during the 2011 M9 rupture. The remaining slip deficit can be attributed to the postseismic processes. Similar conclusions can be drawn for the 2004 M6 Parkfield earthquake. We also estimate the required time of strain accumulation for the 2004 M6 Parkfield earthquake to be ~25 years (confidence interval of [17, 43] years), consistent with the observed average recurrence time of ~22 years for M6 earthquakes in Parkfield. For the Tohoku-Oki earthquake, we estimate the recurrence time of~500-700 years. This new inversion approach for evaluating slip balance can be generally applied to any earthquake for which dense geodetic measurements are available.

  5. Quantifying slip balance in the earthquake cycle: Coseismic slip model constrained by interseismic coupling

    KAUST Repository

    Wang, Lifeng

    2015-11-11

    The long-term slip on faults has to follow, on average, the plate motion, while slip deficit is accumulated over shorter time scales (e.g., between the large earthquakes). Accumulated slip deficits eventually have to be released by earthquakes and aseismic processes. In this study, we propose a new inversion approach for coseismic slip, taking interseismic slip deficit as prior information. We assume a linear correlation between coseismic slip and interseismic slip deficit, and invert for the coefficients that link the coseismic displacements to the required strain accumulation time and seismic release level of the earthquake. We apply our approach to the 2011 M9 Tohoku-Oki earthquake and the 2004 M6 Parkfield earthquake. Under the assumption that the largest slip almost fully releases the local strain (as indicated by borehole measurements, Lin et al., 2013), our results suggest that the strain accumulated along the Tohoku-Oki earthquake segment has been almost fully released during the 2011 M9 rupture. The remaining slip deficit can be attributed to the postseismic processes. Similar conclusions can be drawn for the 2004 M6 Parkfield earthquake. We also estimate the required time of strain accumulation for the 2004 M6 Parkfield earthquake to be ~25 years (confidence interval of [17, 43] years), consistent with the observed average recurrence time of ~22 years for M6 earthquakes in Parkfield. For the Tohoku-Oki earthquake, we estimate the recurrence time of~500-700 years. This new inversion approach for evaluating slip balance can be generally applied to any earthquake for which dense geodetic measurements are available.

  6. Seismogeodesy of the 2014 Mw6.1 Napa earthquake, California: Rapid response and modeling of fast rupture on a dipping strike-slip fault

    Science.gov (United States)

    Melgar, Diego; Geng, Jianghui; Crowell, Brendan W.; Haase, Jennifer S.; Bock, Yehuda; Hammond, William C.; Allen, Richard M.

    2015-07-01

    Real-time high-rate geodetic data have been shown to be useful for rapid earthquake response systems during medium to large events. The 2014 Mw6.1 Napa, California earthquake is important because it provides an opportunity to study an event at the lower threshold of what can be detected with GPS. We show the results of GPS-only earthquake source products such as peak ground displacement magnitude scaling, centroid moment tensor (CMT) solution, and static slip inversion. We also highlight the retrospective real-time combination of GPS and strong motion data to produce seismogeodetic waveforms that have higher precision and longer period information than GPS-only or seismic-only measurements of ground motion. We show their utility for rapid kinematic slip inversion and conclude that it would have been possible, with current real-time infrastructure, to determine the basic features of the earthquake source. We supplement the analysis with strong motion data collected close to the source to obtain an improved postevent image of the source process. The model reveals unilateral fast propagation of slip to the north of the hypocenter with a delayed onset of shallow slip. The source model suggests that the multiple strands of observed surface rupture are controlled by the shallow soft sediments of Napa Valley and do not necessarily represent the intersection of the main faulting surface and the free surface. We conclude that the main dislocation plane is westward dipping and should intersect the surface to the east, either where the easternmost strand of surface rupture is observed or at the location where the West Napa fault has been mapped in the past.

  7. Imbricated slip rate processes during slow slip transients imaged by low-frequency earthquakes

    Science.gov (United States)

    Lengliné, O.; Frank, W.; Marsan, D.; Ampuero, J. P.

    2017-12-01

    Low Frequency Earthquakes (LFEs) often occur in conjunction with transient strain episodes, or Slow Slip Events (SSEs), in subduction zones. Their focal mechanism and location consistent with shear failure on the plate interface argue for a model where LFEs are discrete dynamic ruptures in an otherwise slowly slipping interface. SSEs are mostly observed by surface geodetic instruments with limited resolution and it is likely that only the largest ones are detected. The time synchronization of LFEs and SSEs suggests that we could use the recorded LFEs to constrain the evolution of SSEs, and notably of the geodetically-undetected small ones. However, inferring slow slip rate from the temporal evolution of LFE activity is complicated by the strong temporal clustering of LFEs. Here we apply dedicated statistical tools to retrieve the temporal evolution of SSE slip rates from the time history of LFE occurrences in two subduction zones, Mexico and Cascadia, and in the deep portion of the San Andreas fault at Parkfield. We find temporal characteristics of LFEs that are similar across these three different regions. The longer term episodic slip transients present in these datasets show a slip rate decay with time after the passage of the SSE front possibly as t-1/4. They are composed of multiple short term transients with steeper slip rate decay as t-α with α between 1.4 and 2. We also find that the maximum slip rate of SSEs has a continuous distribution. Our results indicate that creeping faults host intermittent deformation at various scales resulting from the imbricated occurrence of numerous slow slip events of various amplitudes.

  8. Lightning Often Strikes Twice

    Science.gov (United States)

    2005-01-01

    Contrary to popular misconception, lightning often strikes the same place twice. Certain conditions are just ripe for a bolt of electricity to come zapping down; and a lightning strike is powerful enough to do a lot of damage wherever it hits. NASA created the Accurate Location of Lightning Strikes technology to determine the ground strike point of lightning and prevent electrical damage in the immediate vicinity of the Space Shuttle launch pads at Kennedy Space Center. The area surrounding the launch pads is enmeshed in a network of electrical wires and components, and electronic equipment is highly susceptible to lightning strike damage. The accurate knowledge of the striking point is important so that crews can determine which equipment or system needs to be retested following a strike. Accurate to within a few yards, this technology can locate a lightning strike in the perimeter of the launch pad. As an added bonus, the engineers, then knowing where the lightning struck, can adjust the variables that may be attracting the lightning, to create a zone that will be less susceptible to future strikes.

  9. High Frequency Near-Field Ground Motion Excited by Strike-Slip Step Overs

    Science.gov (United States)

    Hu, Feng; Wen, Jian; Chen, Xiaofei

    2018-03-01

    We performed dynamic rupture simulations on step overs with 1-2 km step widths and present their corresponding horizontal peak ground velocity distributions in the near field within different frequency ranges. The rupture speeds on fault segments are determinant in controlling the near-field ground motion. A Mach wave impact area at the free surface, which can be inferred from the distribution of the ratio of the maximum fault-strike particle velocity to the maximum fault-normal particle velocity, is generated in the near field with sustained supershear ruptures on fault segments, and the Mach wave impact area cannot be detected with unsustained supershear ruptures alone. Sub-Rayleigh ruptures produce stronger ground motions beyond the end of fault segments. The existence of a low-velocity layer close to the free surface generates large amounts of high-frequency seismic radiation at step over discontinuities. For near-vertical step overs, normal stress perturbations on the primary fault caused by dipping structures affect the rupture speed transition, which further determines the distribution of the near-field ground motion. The presence of an extensional linking fault enhances the near-field ground motion in the extensional regime. This work helps us understand the characteristics of high-frequency seismic radiation in the vicinities of step overs and provides useful insights for interpreting the rupture speed distributions derived from the characteristics of near-field ground motion.

  10. Precise Relative Location of San Andreas Fault Tremors Near Cholame, CA, Using Seismometer Clusters: Slip on the Deep Extension of the Fault?

    Science.gov (United States)

    Shelly, D. R.; Ellsworth, W. L.; Ryberg, T.; Haberland, C.; Fuis, G.; Murphy, J.; Nadeau, R.; Bürgmann, R.

    2008-12-01

    Non-volcanic tremor, similar in character to that generated at some subduction zones, was recently identified beneath the strike-slip San Andreas Fault (SAF) in central California (Nadeau and Dolenc, 2005). Using a matched filter method, we closely examine a 24-hour period of active SAF tremor and show that, like tremor in the Nankai Trough subduction zone, this tremor is composed of repeated similar events. We take advantage of this similarity to locate detected similar events relative to several chosen events. While low signal-to-noise makes location challenging, we compensate for this by estimating event-pair differential times at 'clusters' of nearby temporary and permanent stations rather than at single stations. We find that the relative locations consistently form a near-linear structure in map view, striking parallel to the surface trace of the SAF. Therefore, we suggest that at least a portion of the tremor occurs on the deep extension of the fault, similar to the situation for subduction zone tremor. Also notable is the small depth range (a few hundred meters or less) of many of the located tremors, a feature possibly analogous to earthquake streaks observed on the shallower portion of the fault. The close alignment of the tremor with the SAF slip orientation suggests a shear slip mechanism, as has been argued for subduction tremor. At times, we observe a clear migration of the tremor source along the fault, at rates of 15-40 km/hr.

  11. Co-seismic slip, post-seismic slip, and largest aftershock associated with the 1994 Sanriku-haruka-oki, Japan, earthquake

    Science.gov (United States)

    Yagi, Yuji; Kikuchi, Masayuki; Nishimura, Takuya

    2003-11-01

    We analyzed continuous GPS data to investigate the spatio-temporal distribution of co-seismic slip, post-seismic slip, and largest aftershock associated with the 1994 Sanriku-haruka-oki, Japan, earthquake (Mw = 7.7). To get better resolution for co-seismic and post-seismic slip distribution, we imposed a weak constraint as a priori information of the co-seismic slip determined by seismic wave analyses. We found that the post-seismic slip during 100 days following the main-shock amount to as much moment release as the main-shock, and that the sites of co-seismic slip and post-seismic slip are partitioning on a plate boundary region in complimentary fashion. The major post-seismic slip was triggered by the mainshock in western side of the co-seismic slip, and the extent of the post-seismic slip is almost unchanged with time. It rapidly developed a shear stress concentration ahead of the slip area, and triggered the largest aftershock.

  12. Controls of earthquake faulting style on near field landslide triggering : the role of coseismic slip

    OpenAIRE

    Tatard, Lucile; Grasso, J. R.

    2013-01-01

    We compare the spatial distributions of seven databases of landslides triggered by M-w=5.6-7.9 earthquakes, using distances normalized by the earthquake fault length. We show that the normalized landslide distance distributions collapse, i.e., the normalized distance distributions overlap whatever the size of the earthquake, separately for the events associated with dip-slip, buried-faulting earthquakes, and surface-faulting earthquakes. The dip-slip earthquakes triggered landslides at larger...

  13. Leakage flow-induced vibrations for variations of a tube-in-tube slip joint

    International Nuclear Information System (INIS)

    Mulcahy, T.M.

    1986-01-01

    Variations in the design of a specific slip joint separating two cantilevered, telescoping tubes conveying water were studied to determine their effect upon the leakage flow-induced vibration self-excitation mechanism known to exist for the original slip joint geometry. The important parameters controlling the self-excitation mechanism were identified, which, along with previous results, allowed the determination of a comprehensive set of design rules to avoid unstable vibrations. This was possible even though a new self-excitation mechanism was found when the engagement of the two tubes was small. 9 refs

  14. Slip effects on MHD flow and heat transfer of ferrofluids over a moving flat plate

    Science.gov (United States)

    Ramli, Norshafira; Ahmad, Syakila; Pop, Ioan

    2017-08-01

    In this study, the problem of MHD flow and heat transfer of ferrofluids over a moving flat plate with slip effect and uniform heat flux is considered. The governing ordinary differential equations are solved via shooting method. The effect of slip parameter on the dimensionless velocity, temperature, skin friction and Nusselt numbers are numerically studied for the three selected ferroparticles; magnetite (Fe3O4), cobalt ferrite (CoFe2O4) and Mn-Zn ferrite (Mn-ZnFe2O4) with water-based fluid. The results indicate that dual solutions exist for a plate moving towards the origin. It is found that the slip process delays the boundary layer separation. Moreover, the velocity and thermal boundary-layer thicknesses decrease in the first solution while increase with the increase of the value of slip parameters in second solution.

  15. Three-dimensional flow analysis and improvement of slip factor model for forward-curved blades centrifugal fan

    International Nuclear Information System (INIS)

    Guo, En Min; Kim, Kwang Yong

    2004-01-01

    This work developed improved slip factor model and correction method to predict flow through impeller in forward-curved centrifugal fan. Both steady and unsteady three-dimensional CFD analyses were performed to validate the slip factor model and the correction method. The results show that the improved slip factor model presented in this paper could provide more accurate predictions for forward-curved centrifugal impeller than the other slip factor models since the present model takes into account the effect of blade curvature. The correction method is provided to predict mass-averaged absolute circumferential velocity at the exit of impeller by taking account of blockage effects induced by the large-scale backflow near the front plate and flow separation within blade passage. The comparison with CFD results also shows that the improved slip factor model coupled with the present correction method provides accurate predictions for mass-averaged absolute circumferential velocity at the exit of impeller near and above the flow rate of peak total pressure coefficient

  16. Fluid Pressures at the Shoe-Floor-Contaminant Interface During Slips: Effects of Tread & Implications on Slip Severity

    Science.gov (United States)

    Beschorner, Kurt E.; Albert, Devon L.; Chambers, April J.; Redfern, Mark S.

    2018-01-01

    Previous research on slip and fall accidents has suggested that pressurized fluid between the shoe and floor is responsible for initiating slips yet this effect has not been verified experimentally. This study aimed to 1) measure hydrodynamic pressures during slipping for treaded and untreaded conditions; 2) determine the effects of fluid pressure on slip severity; and 3) quantify how fluid pressures vary with instantaneous resultant slipping speed, position on the shoe surface, and throughout the progression of the slip. Eighteen subjects walked on known dry and unexpected slippery floors, while wearing treaded and untreaded shoes. Fluid pressure sensors, embedded in the floor, recorded hydrodynamic pressures during slipping. The maximum fluid pressures (mean+/−standard deviation) were significantly higher for the untreaded conditions (124 +/−75 kPa) than the treaded conditions (1.1 +/−0.29 kPa). Maximum fluid pressures were positively correlated with peak slipping speed (r = 0.87), suggesting that higher fluid pressures, which are associated with untreaded conditions, resulted in more severe slips. Instantaneous resultant slipping speed and position of sensor relative to the shoe sole and walking direction explained 41% of the fluid pressure variability. Fluid pressures were primarily observed for untreaded conditions. This study confirms that fluid pressures are relevant to slipping events, consistent with fluid dynamics theory (i.e. the Reynolds equation), and can be modified with shoe tread design. The results suggest that the occurrence and severity of unexpected slips can be reduced by designing shoes/floors that reduce underfoot fluid pressures. PMID:24267270

  17. Coseismic Slip Deficit of the 2017 Mw 6.5 Ormoc Earthquake That Occurred Along a Creeping Segment and Geothermal Field of the Philippine Fault

    Science.gov (United States)

    Yang, Ying-Hui; Tsai, Min-Chien; Hu, Jyr-Ching; Aurelio, Mario A.; Hashimoto, Manabu; Escudero, John Agustin P.; Su, Zhe; Chen, Qiang

    2018-03-01

    Coseismic surface deformation imaged through interferometric synthetic aperture radar (InSAR) measurements was used to estimate the fault geometry and slip distribution of the 2017 Mw 6.5 Ormoc earthquake along a creeping segment of the Philippine Fault on Leyte Island. Our best fitting faulting model suggests that the coseismic rupture occurred on a fault plane with high dip angle of 78.5° and strike angle of 325.8°, and the estimated maximum fault slip of 2.3 m is located at 6.5 km east-northeast of the town of Kananga. The recognized insignificant slip in the Tongonan geothermal field zone implies that the plastic behavior caused by high geothermal gradient underneath the Tongonan geothermal field could prevent the coseismic failure in heated rock mass in this zone. The predicted Coulomb failure stress change shows that a significant positive Coulomb failure stress change occurred along the SE segment of central Philippine Fault with insignificant coseismic slip and infrequent aftershocks, which suggests an increasing risk for future seismic hazard.

  18. Uranium isotopic separation by aerodynamic methods. Final report

    International Nuclear Information System (INIS)

    Davidovitz, P.; Anderson, J.B.; Brook, J.W.; Calia, V.S.; Greene, G.T.

    1979-06-01

    Two aerodynamic separation techniques for uranium enrichment were investigated for technical feasibility and economic viability. These techniques are known as the Jet Membrane and Velocity Slip Processes. Both analytical and laboratory studies were conducted to explore the technical feasibility of the subject processes. The Jet Membrane Process Studies demonstrated that the process was feasible and that a condensable gas carrier is available. The Velocity Slip Studies demonstrated the predicted effects and did not identify a suitable condensable gas carrier. Hence the Velocity Slip Process exhibited a larger power consumption than did the Jet Membrane Process. An independent contractor prepared detailed cost estimates of the process. The independent results indicated that, based on the same costing ground rules, the Velocity Slip process would require 16 times the fixed capital costs and 12 times the cost per separative work unit as compared to the Jet Membrane Process. The same cost structure indicated that the cost per separative work unit for the Jet Membrane process would be two to three times that for the Gas Centrifuge process. There are a number of uncertainties associated with these cost estimates, such that, in the extreme, the costs might be the same. Further, more detailed cost analysis would be required to resolve the uncertainties associated with the initial cost estimates. The conduct of new studies was not considered to be appropriate for EPRI because of the changes in enrichment program management and security philosophy discussed in the text

  19. Testing Pixel Translation Digital Elevation Models to Reconstruct Slip Histories: An Example from the Agua Blanca Fault, Baja California, Mexico

    Science.gov (United States)

    Wilson, J.; Wetmore, P. H.; Malservisi, R.; Ferwerda, B. P.; Teran, O.

    2012-12-01

    We use recently collected slip vector and total offset data from the Agua Blanca fault (ABF) to constrain a pixel translation digital elevation model (DEM) to reconstruct the slip history of this fault. This model was constructed using a Perl script that reads a DEM file (Easting, Northing, Elevation) and a configuration file with coordinates that define the boundary of each fault segment. A pixel translation vector is defined as a magnitude of lateral offset in an azimuthal direction. The program translates pixels north of the fault and prints their pre-faulting position to a new DEM file that can be gridded and displayed. This analysis, where multiple DEMs are created with different translation vectors, allows us to identify areas of transtension or transpression while seeing the topographic expression in these areas. The benefit of this technique, in contrast to a simple block model, is that the DEM gives us a valuable graphic which can be used to pose new research questions. We have found that many topographic features correlate across the fault, i.e. valleys and ridges, which likely have implications for the age of the ABF, long term landscape evolution rates, and potentially provide conformation for total slip assessments The ABF of northern Baja California, Mexico is an active, dextral strike slip fault that transfers Pacific-North American plate boundary strain out of the Gulf of California and around the "Big Bend" of the San Andreas Fault. Total displacement on the ABF in the central and eastern parts of the fault is 10 +/- 2 km based on offset Early-Cretaceous features such as terrane boundaries and intrusive bodies (plutons and dike swarms). Where the fault bifurcates to the west, the northern strand (northern Agua Blanca fault or NABF) is constrained to 7 +/- 1 km. We have not yet identified piercing points on the southern strand, the Santo Tomas fault (STF), but displacement is inferred to be ~4 km assuming that the sum of slip on the NABF and STF is

  20. Seismic slip on clay nano-foliation

    Science.gov (United States)

    Aretusini, S.; Pluemper, O.; Passelègue, F. X.; Spagnuolo, E.; Di Toro, G.

    2017-12-01

    Deformation processes active at seismic slip rates (ca. 1 m/s) on smectite-rich slipping zones are not well understood, although they likely control the mechanical behaviour of: i) subduction zone faults affected by tsunamigenic earthquakes (e.g. Japan Trench affected by Tohoku-Oki 2011 earthquake), ii) plate-boundary faults (e.g. San Andreas Fault), and iii) landslide decollements (e.g. 1963 Vajont landslide). Here we present a set of rotary experiments performed on water-dampened 2 mm thick clay-rich (70% wt. smectite and 30% wt. opal) gouge layers sheared at slip rates V ranging from 0.01 to 1.3 m/s, for 3 m of displacement under 5 MPa normal stress. Microstructural analyses were conducted on pre- and post-sheared gouges using focused ion beam scanning electron and transmission electron microscopy. All sheared gouges were slip weakening in the first 0.1 m of displacement, with friction coefficient decreasing from 0.3-0.45 to 0.5-0.15. Then, with progressive slip, gouges evolved to slip-strengthening (final friction coefficient of 0.35-0.48) at V ≤0.1 m/s and slip-neutral (final friction of 0.05) at V=1.3 m/s. Despite the large difference in the imposed slip rate and frictional behaviour, the slipping zone always consisted of a nano-foliation defined by sub-micrometric smectite crystals wrapping opal grains. The nano-foliated layer thickness decreased from 1.5 mm at V≤0.1 m/s to 0.15 mm at V=1.3 m/s. The presence of a similar nano-foliation in all the smectite-rich wet gouges suggests the activation of similar deformation processes, dominated by frictional slip on grain boundary and basal planes. The variation of deformed thickness with slip rate shows that dynamic weakening, occurring only at seismic slip rates, is controlled by strain localization.

  1. Evidence for fluid-triggered slip in the 2009 Mount Rainier, Washington earthquake swarm

    Science.gov (United States)

    Shelly, David R.; Moran, Seth C.; Thelen, Weston A.

    2013-01-01

    A vigorous swarm of over 1000 small, shallow earthquakes occurred 20–22 September 2009 beneath Mount Rainier, Washington, including the largest number of events ever recorded in a single day at Rainier since seismic stations were installed on the edifice in 1989. Many events were only clearly recorded on one or two stations on the edifice, or they overlapped in time with other events, and thus only ~200 were locatable by manual phase picking. To partially overcome this limitation, we applied waveform-based event detection integrated with precise double-difference relative relocation. With this procedure, detection and location goals are accomplished in tandem, using cross-correlation with continuous seismic data and waveform templates constructed from cataloged events. As a result, we obtained precise locations for 726 events, an improvement of almost a factor of 4. These event locations define a ~850 m long nearly vertical structure striking NNE, with episodic migration outward from the initial hypocenters. The activity front propagates in a manner consistent with a diffusional process. Double-couple-constrained focal mechanisms suggest dominantly near-vertical strike-slip motion on either NNW or ENE striking faults, more than 30° different than the strike of the event locations. This suggests the possibility of en echelon faulting, perhaps with a component of fault opening in a fracture-mesh-type geometry. We hypothesize that the swarm was initiated by a sudden release of high-pressure fluid into preexisting fractures, with subsequent activity triggered by diffusing fluid pressure in combination with stress transfer from the preceding events.

  2. Implementing a C++ Version of the Joint Seismic-Geodetic Algorithm for Finite-Fault Detection and Slip Inversion for Earthquake Early Warning

    Science.gov (United States)

    Smith, D. E.; Felizardo, C.; Minson, S. E.; Boese, M.; Langbein, J. O.; Guillemot, C.; Murray, J. R.

    2015-12-01

    The earthquake early warning (EEW) systems in California and elsewhere can greatly benefit from algorithms that generate estimates of finite-fault parameters. These estimates could significantly improve real-time shaking calculations and yield important information for immediate disaster response. Minson et al. (2015) determined that combining FinDer's seismic-based algorithm (Böse et al., 2012) with BEFORES' geodetic-based algorithm (Minson et al., 2014) yields a more robust and informative joint solution than using either algorithm alone. FinDer examines the distribution of peak ground accelerations from seismic stations and determines the best finite-fault extent and strike from template matching. BEFORES employs a Bayesian framework to search for the best slip inversion over all possible fault geometries in terms of strike and dip. Using FinDer and BEFORES together generates estimates of finite-fault extent, strike, dip, preferred slip, and magnitude. To yield the quickest, most flexible, and open-source version of the joint algorithm, we translated BEFORES and FinDer from Matlab into C++. We are now developing a C++ Application Protocol Interface for these two algorithms to be connected to the seismic and geodetic data flowing from the EEW system. The interface that is being developed will also enable communication between the two algorithms to generate the joint solution of finite-fault parameters. Once this interface is developed and implemented, the next step will be to run test seismic and geodetic data through the system via the Earthworm module, Tank Player. This will allow us to examine algorithm performance on simulated data and past real events.

  3. Slip of the capital femoral epiphysis: Revival of a method of assessment

    International Nuclear Information System (INIS)

    Billing, L.; Ekloef, O.

    1984-01-01

    A simple and exact method for evaluation of suspected or overt slip of the femoral capital epiphysis is revived. This procedure gives an estimate of all degrees of abnormality from the early stages to those with gross deformity. In our experience slip of the femoral capital epiphysis is always posterior and in approximately 80% of cases bilateral. Therefore, bot hips should be examined whenever this condition is suspected. The method provides for examination of each hip separately. Strict adherence to the procedure also provides a precise way of assessing the femoral anteversion angle, significant in many orthopedic disorders. For the latter purpose access to a particular nomogram is mandatory. (orig.)

  4. Electro-optical hybrid slip ring

    Science.gov (United States)

    Hong, En

    2005-11-01

    The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility

  5. Automated identification and modeling aseismic slip events on Kilauea Volcano, Hawaii

    Science.gov (United States)

    Desmarais, E. K.; Segall, P.; Miklius, A.

    2006-12-01

    Several aseismic slip events have been observed on the south flank of Kilauea volcano, Hawaii (Cervelli et al., Nature, 2002; Brooks et al., EPSL, 2006; Segall et al., Nature, 2006). These events are identified as spatially coherent offsets in GPS time series. We have interpreted the events as slip on a sub-horizontal surface at depths consistent with a decollement under Kilauea's south flank. In order to determine whether smaller slow slip events are present in the time series, we developed an algorithm that searches for coherent displacement patterns similar to the known slow slip events. We compute candidate displacements by taking a running difference of the mean position 6 days before and after a window of 6 days centered on the candidate time step. The candidate displacements are placed in a 3N dimensional data vector, where N is the number of stations. We then compute the angle, in the 3N dimensional data space, between the candidate displacement and a reference vector at each time step. The reference vector is a stack of displacements due to the four largest known slow slip events. Small angles indicate similar displacement patterns, regardless of amplitude. The algorithm strongly identifies four events (September 20, 1998, November 9, 2000, December 16, 2002, and January 26, 2005), each separated by approximately 2.11 years. The algorithm also identified one smaller event (March 3, 1998) that preceeded the September 1998 event by ~ 200 days, and another event (July 4, 2003) that followed the December 2002 event by ~ 200 days. These smaller, 'paired' events appear to alternate rupturing of the eastern and western parts of the south flank. Each of the slow slip events is correlated with an increase, sometimes slight, in microseismicity on the south flank of Kilauea. The temporal evolution of the microseismicity for the 2005 event is well explained by increased stress due to the slow slip (Segall et al., Nature, 2006). The microearthquakes, at depths of 6

  6. Strain rate effect on fault slip and rupture evolution: Insight from meter-scale rock friction experiments

    Science.gov (United States)

    Xu, Shiqing; Fukuyama, Eiichi; Yamashita, Futoshi; Mizoguchi, Kazuo; Takizawa, Shigeru; Kawakata, Hironori

    2018-05-01

    We conduct meter-scale rock friction experiments to study strain rate effect on fault slip and rupture evolution. Two rock samples made of Indian metagabbro, with a nominal contact dimension of 1.5 m long and 0.1 m wide, are juxtaposed and loaded in a direct shear configuration to simulate the fault motion. A series of experimental tests, under constant loading rates ranging from 0.01 mm/s to 1 mm/s and under a fixed normal stress of 6.7 MPa, are performed to simulate conditions with changing strain rates. Load cells and displacement transducers are utilized to examine the macroscopic fault behavior, while high-density arrays of strain gauges close to the fault are used to investigate the local fault behavior. The observations show that the macroscopic peak strength, strength drop, and the rate of strength drop can increase with increasing loading rate. At the local scale, the observations reveal that slow loading rates favor generation of characteristic ruptures that always nucleate in the form of slow slip at about the same location. In contrast, fast loading rates can promote very abrupt rupture nucleation and along-strike scatter of hypocenter locations. At a given propagation distance, rupture speed tends to increase with increasing loading rate. We propose that a strain-rate-dependent fault fragmentation process can enhance the efficiency of fault healing during the stick period, which together with healing time controls the recovery of fault strength. In addition, a strain-rate-dependent weakening mechanism can be activated during the slip period, which together with strain energy selects the modes of fault slip and rupture propagation. The results help to understand the spectrum of fault slip and rock deformation modes in nature, and emphasize the role of heterogeneity in tuning fault behavior under different strain rates.

  7. Numerical analysis for the stick-slip vibration of a transversely moving beam in contact with a frictional wall

    Science.gov (United States)

    Won, Hong-In; Chung, Jintai

    2018-04-01

    This paper presents a numerical analysis for the stick-slip vibration of a transversely moving beam, considering both stick-slip transition and friction force discontinuity. The dynamic state of the beam was separated into the stick state and the slip state, and boundary conditions were defined for both. By applying the finite element method, two matrix-vector equations were derived: one for stick state and the other for slip state. However, the equations have different degrees of freedom depending on whether the end of a beam sticks or slips, so we encountered difficulties in time integration. To overcome the difficulties, we proposed a new numerical technique to alternatively use the matrix-vector equations with different matrix sizes. In addition, to eliminate spurious high-frequency responses, we applied the generalized-α time integration method with appropriate value of high-frequency numerical dissipation. Finally, the dynamic responses of stick-slip vibration were analyzed in time and frequency domains: the dynamic behavior of the beam was explained to facilitate understanding of the stick-slip motion, and frequency characteristics of the stick-slip vibration were investigated in relation to the natural frequencies of the beam. The effects of the axial load and the moving speed upon the dynamic response were also examined.

  8. Identification of slip surface location by TLS-GPS datafor landslide mitigation case study: Ciloto-Puncak, West Java

    Energy Technology Data Exchange (ETDEWEB)

    Sadarviana, Vera, E-mail: vsadarviana@gmail.com; Hasanuddin, A. Z.; Joenil, G. K.; Irwan; Wijaya, Dudy; Ilman, H.; Agung, N.; Achmad, R. T.; Pangeran, C.; Martin, S.; Gamal, M. [Geodesy Research Group, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40132, West Java (Indonesia); Santoso, Djoko [Geophysics Engineering Research Group, Faculty of Geoscience and Mineral Engineering, Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40132, West Java (Indonesia)

    2015-04-24

    Landslide can prevented by understanding the direction of movement to the safety evacuation track or slip surface location to hold avalanches. Slip surface is separating between stable soil and unstable soil in the slope. The slip surface location gives information about stable material depth. The information can be utilize to mitigate technical step, such as pile installation to keep construction or settlement safe from avalanches.There are two kinds landslide indicators which are visualization and calculation. By visualization, landslide identified from soil crack or scarp. Scarp is a scar of exposed soil on the landslide. That identification can be done by Terrestrial Laser Scanner (TLS) Image. Shape of scarp shows type of slip surface, translation or rotational. By calculation, kinematic and dynamic mathematic model will give vector, velocity and acceleration of material movement. In this calculation need velocity trend line at GPS point from five GPS data campaign. From intersection of trend lines it will create curves or lines of slip surface location. The number of slip surface can be known from material movement direction in landslide zone.Ciloto landslide zone have complicated phenomenon because that zone have influence from many direction of ground water level pressure. The pressure is causes generating several slip surface in Ciloto zone. Types of Ciloto slip surface have mix between translational and rotational type.

  9. Identification of slip surface location by TLS-GPS datafor landslide mitigation case study: Ciloto-Puncak, West Java

    International Nuclear Information System (INIS)

    Sadarviana, Vera; Hasanuddin, A. Z.; Joenil, G. K.; Irwan; Wijaya, Dudy; Ilman, H.; Agung, N.; Achmad, R. T.; Pangeran, C.; Martin, S.; Gamal, M.; Santoso, Djoko

    2015-01-01

    Landslide can prevented by understanding the direction of movement to the safety evacuation track or slip surface location to hold avalanches. Slip surface is separating between stable soil and unstable soil in the slope. The slip surface location gives information about stable material depth. The information can be utilize to mitigate technical step, such as pile installation to keep construction or settlement safe from avalanches.There are two kinds landslide indicators which are visualization and calculation. By visualization, landslide identified from soil crack or scarp. Scarp is a scar of exposed soil on the landslide. That identification can be done by Terrestrial Laser Scanner (TLS) Image. Shape of scarp shows type of slip surface, translation or rotational. By calculation, kinematic and dynamic mathematic model will give vector, velocity and acceleration of material movement. In this calculation need velocity trend line at GPS point from five GPS data campaign. From intersection of trend lines it will create curves or lines of slip surface location. The number of slip surface can be known from material movement direction in landslide zone.Ciloto landslide zone have complicated phenomenon because that zone have influence from many direction of ground water level pressure. The pressure is causes generating several slip surface in Ciloto zone. Types of Ciloto slip surface have mix between translational and rotational type

  10. The Palos Verdes Fault offshore southern California: late Pleistocene to present tectonic geomorphology, seascape evolution and slip rate estimate based on AUV and ROV surveys

    Science.gov (United States)

    Brothers, Daniel S.; Conrad, James E.; Maier, Katherine L.; Paull, Charles K.; McGann, Mary L.; Caress, David W.

    2015-01-01

    The Palos Verdes Fault (PVF) is one of few active faults in Southern California that crosses the shoreline and can be studied using both terrestrial and subaqueous methodologies. To characterize the near-seafloor fault morphology, tectonic influences on continental slope sedimentary processes and late Pleistocene to present slip rate, a grid of high-resolution multibeam bathymetric data, and chirp subbottom profiles were acquired with an autonomous underwater vehicle (AUV) along the main trace of PVF in water depths between 250 and 600 m. Radiocarbon dates were obtained from vibracores collected using a remotely operated vehicle (ROV) and ship-based gravity cores. The PVF is expressed as a well-defined seafloor lineation marked by subtle along-strike bends. Right-stepping transtensional bends exert first-order control on sediment flow dynamics and the spatial distribution of Holocene depocenters; deformed strata within a small pull-apart basin record punctuated growth faulting associated with at least three Holocene surface ruptures. An upper (shallower) landslide scarp, a buried sedimentary mound, and a deeper scarp have been right-laterally offset across the PVF by 55 ± 5, 52 ± 4 , and 39 ± 8 m, respectively. The ages of the upper scarp and buried mound are approximately 31 ka; the age of the deeper scarp is bracketed to 17–24 ka. These three piercing points bracket the late Pleistocene to present slip rate to 1.3–2.8 mm/yr and provide a best estimate of 1.6–1.9 mm/yr. The deformation observed along the PVF is characteristic of strike-slip faulting and accounts for 20–30% of the total right-lateral slip budget accommodated offshore Southern California.

  11. Geomorphic Evidence of a Complex late-Cenozoic Uplift and Lateral Displacement History Along the 2013 M7.7 Baluchistan, Pakistan Strike-slip Rupture

    Science.gov (United States)

    Harbor, D. J.; Barnhart, W. D.

    2017-12-01

    The 2013 M7.7 Baluchistan earthquake in southern Pakistan ruptured 200 km of the north-dipping Hoshab reverse fault with dominantly lateral motion, clearly at odds with the regional topography created by previous reverse fault offsets. The kinematics of this earthquake led to the hypotheses that the Hoshab fault may alternatively slip in a reverse and lateral sense (bi-modal slip), and that the southeast Makran rotates as a uniform block around the fault (ball-and-socket rotation). Here, we use river profiles, regional relief, fault locations, and detailed geomorphic maps derived from optical imagery and DEMs to evaluate the recent uplift history of this region. We find that late Cenozoic fault zone geomorphology supports a spatially complex transition from lateral-dominated offsets in the NE to reverse-dominated offsets in the SW. Additionally, fault zone geomorphology suggests that the location of the Hoshab fault itself may change through time, leading to active incision of footwall alluvial fans and pediments. Stream profiles likewise record incision patterns that vary along the Hoshab fault. Incision and deposition in the SW are illustrative of relative footwall subsidence, consistent with recent uplift on the Hoshab fault; whereas incision and deposition in the NE are illustrative of relative footwall uplift consistent with ongoing regional uplift due to ball-and-socket rotations and dominantly lateral offsets along the northern Hoshab fault. The largest streams also record multiple, discrete, base-level drops, including the presence of convex-up river profiles in the hanging wall of the Hoshab fault. These profiles along hanging wall streams highlight a complex spatial and temporal history of reverse offset, lateral channel offset, and base-level resetting in regional streams that are altogether inconsistent with the kinematics of the 2013 earthquake alone, but that are consistent with the bi-modal slip model. Additionally, the evidence of footwall uplift in

  12. Morphology and slip rate of the Hurunui section of the Hope Fault, South Island, New Zealand

    International Nuclear Information System (INIS)

    Langridge, R.M.; Berryman, K.R.

    2005-01-01

    The Hurunui section of the Hope Fault is a newly defined, 42 km long geomorphic fault section which extends from Harper Pass to the Hope-Boyle River confluence. Reconnaissance mapping along the Hurunui section from Hope Shelter to Harper Pass provided new data on its location, geomorphology, displacement, and slip rate. More than 200 previously published field observations of dextrally and vertically displaced landforms along the fault provide data on the distribution of displacement along the fault trace. Five radiocarbon dates found in association with offset geomorphic features are presented and two new measures of dextral slip rate are calculated. At McKenzie Stream, a late Holocene fan complex is cut by the Hope Fault. Young abandoned and active channels on this surface show dextral offsets of up to 22 ± 2 m along a south-facing scarp with a height of up to 5 m. Woody litter from a unit in this complex has yielded a radiocarbon age of 2331 ± 55 yr BP and a corresponding minimum horizontal slip rate of 8.1-11.0 mm/yr. At Macs Knob, large dextral deflections of stream catchments are linked to episodes of glacial resetting of the landscape. Correlation of the offset of 'Macs stream' (166 ± 17 m) with a post-Aranuian age peat (10,782 ± 60 yr BP) yields a maximum horizontal slip rate of 13.0 ± 1.5 mm/yr. The single-event dextral displacement, based on offset stream channels at McKenzie fan, is 3.2-3.8 m (av. c. 3.4 m). The ratio of dextral to vertical slip is c. 7 ± 2:1, indicating that the Hope Fault has a dominantly strike-slip sense of motion. The average recurrence interval for the last 5-7 events (i.e., to produce 19-24 m slip at McKenzie fan) is 310-490 yr. The age of the most recent surface-rupturing earthquake at this site is not known, though felt effects, fault scaling, and landscape arguments indicate it was not the AD 1888 North Canterbury earthquake. (author). 48 refs., 10 figs., 2 tabs

  13. Unravelling the Mysteries of Slip Histories, Validating Cosmogenic 36Cl Derived Slip Rates on Normal Faults

    Science.gov (United States)

    Goodall, H.; Gregory, L. C.; Wedmore, L.; Roberts, G.; Shanks, R. P.; McCaffrey, K. J. W.; Amey, R.; Hooper, A. J.

    2017-12-01

    The cosmogenic isotope chlorine-36 (36Cl) is increasingly used as a tool to investigate normal fault slip rates over the last 10-20 thousand years. These slip histories are being used to address complex questions, including investigating slip clustering and understanding local and large scale fault interaction. Measurements are time consuming and expensive, and as a result there has been little work done validating these 36Cl derived slip histories. This study aims to investigate if the results are repeatable and therefore reliable estimates of how normal faults have been moving in the past. Our approach is to test if slip histories derived from 36Cl are the same when measured at different points along the same fault. As normal fault planes are progressively exhumed from the surface they accumulate 36Cl. Modelling these 36Cl concentrations allows estimation of a slip history. In a previous study, samples were collected from four sites on the Magnola fault in the Italian Apennines. Remodelling of the 36Cl data using a Bayesian approach shows that the sites produced disparate slip histories, which we interpret as being due to variable site geomorphology. In this study, multiple sites have been sampled along the Campo Felice fault in the central Italian Apennines. Initial results show strong agreement between the sites we have processed so far and a previous study. This indicates that if sample sites are selected taking the geomorphology into account, then 36Cl derived slip histories will be highly similar when sampled at any point along the fault. Therefore our study suggests that 36Cl derived slip histories are a consistent record of fault activity in the past.

  14. Fixed recurrence and slip models better predict earthquake behavior than the time- and slip-predictable models 1: repeating earthquakes

    Science.gov (United States)

    Rubinstein, Justin L.; Ellsworth, William L.; Chen, Kate Huihsuan; Uchida, Naoki

    2012-01-01

    The behavior of individual events in repeating earthquake sequences in California, Taiwan and Japan is better predicted by a model with fixed inter-event time or fixed slip than it is by the time- and slip-predictable models for earthquake occurrence. Given that repeating earthquakes are highly regular in both inter-event time and seismic moment, the time- and slip-predictable models seem ideally suited to explain their behavior. Taken together with evidence from the companion manuscript that shows similar results for laboratory experiments we conclude that the short-term predictions of the time- and slip-predictable models should be rejected in favor of earthquake models that assume either fixed slip or fixed recurrence interval. This implies that the elastic rebound model underlying the time- and slip-predictable models offers no additional value in describing earthquake behavior in an event-to-event sense, but its value in a long-term sense cannot be determined. These models likely fail because they rely on assumptions that oversimplify the earthquake cycle. We note that the time and slip of these events is predicted quite well by fixed slip and fixed recurrence models, so in some sense they are time- and slip-predictable. While fixed recurrence and slip models better predict repeating earthquake behavior than the time- and slip-predictable models, we observe a correlation between slip and the preceding recurrence time for many repeating earthquake sequences in Parkfield, California. This correlation is not found in other regions, and the sequences with the correlative slip-predictable behavior are not distinguishable from nearby earthquake sequences that do not exhibit this behavior.

  15. Velocity- and slip-dependent weakening on the Tohoku plate boundary fault: shallow coseismic slip facilitated by foreshock afterslip

    Science.gov (United States)

    Ito, Y.; Ikari, M.; Ujiie, K.; Kopf, A.

    2016-12-01

    Understanding of role of slow earthquakes as they relate to the occurrence of both megathrust earthquakes and tsunami earthquakes is necessary to mitigate these disasters in the near future. Laboratory shearing experiments is one of important approach to evaluate these relationships. Here, we use powdered gouge samples from JFAST (IODP Expedition 343) Hole C0019E, core sample 17R-1, which is the plate boundary fault zone in the Japan Trench subduction zone. In this region, both large coseismic slip during the 2011 Tohoku-Oki earthquake as well as discrete slow slip events (SSE) have occurred. Experiments were conducted in a single-direct shear apparatus under normal stress of 16 MPa, with total shear displacements of up to 16 mm. We evaluate both the velocity- and slip-dependence of friction by extracting the velocity-dependent friction parameters a, b, and Dc, and measuring the rate of change in friction coefficient with shear displacement as the slip-dependence of friction. We report that in friction experiments using the Tohoku fault zone samples, an increase in sliding velocity exceeding that of earthquake afterslip can induce a change from steady-state frictional strength or slip hardening friction to slip-weakening frictional behavior. Our results show that the slip weakening is observed when the slip velocity exceeds 1 x 10-6 m/s during our experiments, while steady-state frictional strength or slip hardening is observed below 1x10-6 m/s. In the Japan Trench region, two slow events were observed at the downdip edge of the mainshock coseismic slip zone (< 30 m) were observed. These are an episodic SSE with a slip velocity of 0.1 x 10-6, and afterslip after the largest foreshock with a slip velocity of 2 x 10-6 m/s. This suggests that the afterslip may have facilitated the large coseismic slip during the mainshock on the plate boundary fault of the Tohoku-Oki earthquake.

  16. Spatiotemporal evolution of premonitory fault slip prior to stick-slip instability: New insight into the earthquake preparation

    Science.gov (United States)

    Zhuo, Y. Q.; Liu, P.; Guo, Y.; Ji, Y.; Ma, J.

    2017-12-01

    Premonitory fault slip, which begins with quasistatic propagation followed by quasidynamic propagation, may be a key clue bridging the "stick" state and "slip" state of a fault. More attentions have been paid for a long time to the temporal resolution of measurement than the spatial resolution, leading to the incomplete interpretation for the spatial evolution of premonitory slip, particularly during the quasistatic phase. In the present study, measurement of the quasistatic propagation of premonitory slip is achieved at an ultrahigh spatial resolution via a digital image correlation method. Multiple premonitory slip zones are observed and found to be controlled spatially by the fault contact heterogeneity, particularly the strong contact patches that prevent the propagation of premonitory slip and accumulate strain. As a result, premonitory slip is accelerated within constrained week contact spaces and consequently triggers the breakout of quasidynamic propagation. The results provide new insights into the quasistatic propagation of premonitory slip and may offer new interpretations for the earthquake nucleation process. This work is fund by the National Natural Science Foundation of China (Grant No. 41572181), the Basic Scientific Funding of Chinese National Nonprofit Institutes (Grant No. IGCEA1415, IGCEA1525), and the Early-Stage Work of Key Breakthrough Plan in Seismology from China Earthquake Administration.

  17. Stabilizing Stick-Slip Friction

    International Nuclear Information System (INIS)

    Capozza, Rosario; Barel, Itay; Urbakh, Michael; Rubinstein, Shmuel M.; Fineberg, Jay

    2011-01-01

    Even the most regular stick-slip frictional sliding is always stochastic, with irregularity in both the intervals between slip events and the sizes of the associated stress drops. Applying small-amplitude oscillations to the shear force, we show, experimentally and theoretically, that the stick-slip periods synchronize. We further show that this phase locking is related to the inhibition of slow rupture modes which forces a transition to fast rupture, providing a possible mechanism for observed remote triggering of earthquakes. Such manipulation of collective modes may be generally relevant to extended nonlinear systems driven near to criticality.

  18. Stick-slip Cycles and Tidal Modulation of Ice Stream Flow

    Science.gov (United States)

    Lipovsky, B.; Dunham, E. M.

    2016-12-01

    The reactivation of a single dormant Antarctic ice stream would double the continent's mass imbalance. Despite importance of understanding the likelihood of such an event, direct observation of the basal processes that lead to the activation and stagnation of streaming ice are minimal. As the only ice stream undergoing stagnation, the Whillans Ice Plain (WIP) occupies a central role in our understanding of these subglacial processes. Complicating matters is the observation, from GPS records, that the WIP experiences most of its motion during episodes of rapid sliding. These sliding events are tidally modulated and separated by 12 hour periods of quiescence. We conduct numerical simulations of ice stream stick-slip cycles. Our simulations include rate- and state-dependent frictional sliding, tidal forcing, inertia, upstream loading in a cross-stream, thickness-averaged formulation. Our principal finding is that ice stream motion may respond to ocean tidal forcing with one of two end member behaviors. In one limit, tidally modulated slip events have rupture velocities that approach the shear wave speed and slip events have a duration that scales with the ice stream width divided by the shear wave speed. In the other limit, tidal modulation results in ice stream sliding velocities with lower amplitude variation but at much longer timescales, i.e. semi-diurnal and longer. This latter behavior more closely mimics the behavior of several active ice streams (Bindschadler, Rutford). We find that WIP slip events exist between these two end member behaviors: rupture velocities are far below the inertial limit yet sliding occurs only episodically. The continuum of sliding behaviors is governed by a critical ice stream width over which slip event nucleate. When the critical width is much longer than the ice stream width, slip events are unable to nucleate. The critical width depends on the subglacial effective pressure, ice thickness, and frictional and elastic constitutive

  19. Slip rate and tremor genesis in Cascadia

    Science.gov (United States)

    Wech, Aaron G.; Bartlow, Noel M.

    2014-01-01

    At many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

  20. Calculations of intersection cross-slip activation energies in fcc metals using nudged elastic band method

    International Nuclear Information System (INIS)

    Rao, S.I.; Dimiduk, D.M.; Parthasarathy, T.A.; El-Awady, J.; Woodward, C.; Uchic, M.D.

    2011-01-01

    The nudged elastic band (NEB) method is used to evaluate activation energies for dislocation intersection cross-slip in face-centered cubic (fcc) nickel and copper, to extend our prior work which used an approximate method. In this work we also extend the study by including Hirth locks (HL) in addition to Lomer-Cottrell locks and glide locks (GL). Using atomistic (molecular statics) simulations with embedded atom potentials we evaluated the activation barrier for a dislocation to transform from fully residing on the glide plane to fully residing on the cross-slip plane when intersecting a 120 o forest dislocation in both Ni and Cu. The initial separation between the screw and the intersecting dislocation on the (1 1 1) glide plane is varied to find a minimum in the activation energy. The NEB method gives energies that are ∼10% lower than those reported in our prior work. It is estimated that the activation energies for cross-slip from the fully glide plane state to the partially cross-slipped state at the 120 o intersection forming GL in Ni and Cu are ∼0.47 and ∼0.65 eV, respectively, and from the fully cross-slip plane state to the partially cross-slipped state forming LC are ∼0.68 and ∼0.67 eV. The activation energies for cross-slip from the fully glide plane state to the partially cross-slipped state at the 120 o intersection forming HL in Ni and Cu are estimated to be ∼0.09 and ∼0.31 eV, respectively. These values are a factor of 3-20 lower than the activation energy for bulk cross-slip in Ni and, a factor of 2-6 lower than the activation energy for cross-slip in Cu estimated by Friedel-Escaig analysis. These results suggest that cross-slip should nucleate preferentially at selected screw dislocation intersections in fcc materials and the activation energies for such mechanisms are also a function of stacking fault energy.

  1. Analytical approximations for stick-slip vibration amplitudes

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Fidlin, A.

    2003-01-01

    , the amplitudes, and the base frequencies of friction-induced stick¿slip and pure-slip oscillations. For stick¿slip oscillations, this is accomplished by using perturbation analysis for the finite time interval of the stick phase, which is linked to the subsequent slip phase through conditions of continuity...

  2. The 2014, MW6.9 North Aegean earthquake: seismic and geodetic evidence for coseismic slip on persistent asperities

    Science.gov (United States)

    Konca, Ali Ozgun; Cetin, Seda; Karabulut, Hayrullah; Reilinger, Robert; Dogan, Ugur; Ergintav, Semih; Cakir, Ziyadin; Tari, Ergin

    2018-05-01

    We report that asperities with the highest coseismic slip in the 2014 MW6.9 North Aegean earthquake persisted through the interseismic, coseismic and immediate post-seismic periods. We use GPS and seismic data to obtain the source model of the 2014 earthquake, which is located on the western extension of the North Anatolian Fault (NAF). The earthquake ruptured a bilateral, 90 km strike-slip fault with three slip patches: one asperity located west of the hypocentre and two to the east with a rupture duration of 40 s. Relocated pre-earthquake seismicity and aftershocks show that zones with significant coseismic slip were relatively quiet during both the 7 yr of interseismic and the 3-month aftershock periods, while the surrounding regions generated significant seismicity during both the interseismic and post-seismic periods. We interpret the unusually long fault length and source duration, and distribution of pre- and post-main-shock seismicity as evidence for a rupture of asperities that persisted through strain accumulation and coseismic strain release in a partially coupled fault zone. We further suggest that the association of seismicity with fault creep may characterize the adjacent Izmit, Marmara Sea and Saros segments of the NAF. Similar behaviour has been reported for sections of the San Andreas Fault, and some large subduction zones, suggesting that the association of seismicity with creeping fault segments and rapid relocking of asperities may characterize many large earthquake faults.

  3. Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

    Science.gov (United States)

    Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.

    2016-09-01

    The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.

  4. The prevention of slipping accidents: a review and discussion of work related to the methodology of measuring slip resistance

    OpenAIRE

    Leclercq , Sylvie

    1999-01-01

    International audience; The recommendations made after the analysis of accidents following an incident of slipping often include the use of anti-slip footwear and/or the installation of an anti-slip floor covering. Such recommendations make it necessary to study biomechanical and tribologic phenomena that occur during slipping, in particular in order to develop criteria for the evaluation of the slip resistance of footwear and floor surfaces. Consequently, research which deals with the preven...

  5. Gait Retraining From Rearfoot Strike to Forefoot Strike does not change Running Economy.

    Science.gov (United States)

    Roper, Jenevieve Lynn; Doerfler, Deborah; Kravitz, Len; Dufek, Janet S; Mermier, Christine

    2017-12-01

    Gait retraining is a method for management of patellofemoral pain, which is a common ailment among recreational runners. The present study investigated the effects of gait retraining from rearfoot strike to forefoot strike on running economy, heart rate, and respiratory exchange ratio immediately post-retraining and one-month post-retraining in recreational runners with patellofemoral pain. Knee pain was also measured. Sixteen participants (n=16) were randomly placed in the control (n=8) or experimental (n=8) group. A 10-minute treadmill RE test was performed by all subjects. The experimental group performed eight gait retraining running sessions where foot strike pattern was switched from rearfoot strike to forefoot strike, while the control group received no intervention. There were no significant differences for running economy (p=0.26), respiratory exchange ratio (p=0.258), or heart rate (p=0.248) between the groups. Knee pain reported on a visual analog scale was also significantly reduced (pstrike to forefoot strike did not affect running economy up to one-month post-retraining while reducing running-related patellofemoral pain. © Georg Thieme Verlag KG Stuttgart · New York.

  6. The 12th June 2017 Mw = 6.3 Lesvos earthquake from detailed seismological observations

    Science.gov (United States)

    Papadimitriou, P.; Kassaras, I.; Kaviris, G.; Tselentis, G.-A.; Voulgaris, N.; Lekkas, E.; Chouliaras, G.; Evangelidis, C.; Pavlou, K.; Kapetanidis, V.; Karakonstantis, A.; Kazantzidou-Firtinidou, D.; Fountoulakis, I.; Millas, C.; Spingos, I.; Aspiotis, T.; Moumoulidou, A.; Skourtsos, E.; Antoniou, V.; Andreadakis, E.; Mavroulis, S.; Kleanthi, M.

    2018-04-01

    A major earthquake (Mwö=ö6.3) occurred on the 12th of June 2017 (12:28 GMT) offshore, south of the SE coast of Lesvos Island, at a depth of 13ökm, in an area characterized by normal faulting with an important strike-slip component in certain cases. Over 900 events of the sequence between 12 and 30 June 2017 were manually analyzed and located, employing an optimized local velocity model. Double-difference relocation revealed seven spatially separated groups of events, forming two linear branches, roughly aligned N130°E, compatible with the strike of known mapped faults along the southern coast of Lesvos Island. Spatiotemporal analysis indicated gradual migration of seismicity towards NW and SE from the margins of the main rupture, while a strong secondary sequence at a separate fault patch SE of the mainshock, oriented NW-SE, was triggered by the largest aftershock (Mwö=ö5.2) that occurred on 17 June. The focal mechanisms of the mainshock (φö=ö122°, δö=ö40° and λö=ö-83°) and of the major aftershocks were determined using regional moment tensor inversion. In most cases normal faulting was revealed with the fault plane oriented in a NW-SE direction, dipping SW, with the exception of the largest aftershock that was characterized by strike-slip faulting. Stress inversion revealed a complex stress field south of Lesvos, related both to normal, in an approximate E-W direction, and strike-slip faulting. All aftershocks outside the main rupture, where gradual seismicity migration was observed, are located within the positive lobes of static stress transfer determined by applying the Coulomb criterion for the mainshock. Stress loading on optimal faults under a strike-slip regime explains the occurrence of the largest aftershock and the seismicity that was triggered at the eastern patch of the rupture zone.

  7. Magnetic resonance imaging at primary diagnosis cannot predict subsequent contralateral slip in slipped capital femoral epiphysis

    Energy Technology Data Exchange (ETDEWEB)

    Wensaas, Anders [Akershus University Hospital, Department of Orthopaedic Surgery, Loerenskog (Norway); Wiig, Ola; Terjesen, Terje [Oslo University Hospital, Department of Orthopaedic Surgery, Rikshospitalet (Norway); Castberg Hellund, Johan; Khoshnewiszadeh, Behzad [Oslo University Hospital, Department of Radiology and Nuclear Medicine, Ullevaal (Norway)

    2017-12-15

    Prophylactic fixation of the contralateral hip in slipped capital femoral epiphysis (SCFE) is controversial, and no reliable method has been established to predict subsequent contralateral slip. The main purpose of this study was to evaluate if magnetic resonance imaging (MRI) performed at primary diagnosis could predict future contralateral slip. Twenty-two patients with unilateral SCFE were included, all had MRI of both hips taken before operative fixation. Six different parameters were measured on the MRI: the MRI slip angle, the greatest focal widening of the physis, the global widening of the physis measured at three locations (the midpoint of the physis and 1 cm lateral and medial to the midpoint), periphyseal (epiphyseal and metaphyseal) bone marrow edema, the presence of pathological joint effusion, and the amount of joint effusion measured from the lateral edge of the greater trochanter. Mean follow-up was 33 months (range, 16-63 months). Six patients were treated for contralateral slip during the follow-up time and a comparison of the MRI parameters of the contralateral hip in these six patients and in the 16 patients that remained unilateral was done to see if subsequent contralateral slip was possible to predict at primary diagnosis. All MRI parameters were significantly altered in hips with established SCFE compared with the contralateral hips. However, none of the MRI parameters showed any significant difference between patients who had a subsequent contralateral slip and those that remained unilateral. MRI taken at primary diagnosis could not predict future contralateral slip. (orig.)

  8. Modeling and Analyzing the Slipping of the Ball Screw

    Directory of Open Access Journals (Sweden)

    Nannan Xu

    Full Text Available AbstractThis paper aims to set up the ball systematic slipping model and analyze the slipping characteristics caused by different factors for a ball screw operating at high speeds. To investigate the ball screw slipping mechanism, transformed coordinate system should be established firstly. Then it is used to set up mathematical modeling for the ball slipping caused by the three main reasons and the speed of slipping can be calculated. Later, the influence of the contact angle, helix angle and screw diameter for ball screw slipping will be analyzed according to the ball slipping model and slipping speeds equation and the slipping analysis will be obtained. Finally, curve of slipping analysis and that of mechanical efficiency of the ball screw analysis by Lin are compared, which will indirectly verify the correctness of the slipping model. The slipping model and the curve of slipping analysis established in this paper will provide theory basis for reducing slipping and improving the mechanical efficiency of a ball screw operating at high speeds.

  9. Slip of Spreading Viscoplastic Droplets.

    Science.gov (United States)

    Jalaal, Maziyar; Balmforth, Neil J; Stoeber, Boris

    2015-11-10

    The spreading of axisymmetric viscoplastic droplets extruded slowly on glass surfaces is studied experimentally using shadowgraphy and swept-field confocal microscopy. The microscopy furnishes vertical profiles of the radial velocity using particle image velocimetry (PIV) with neutrally buoyant tracers seeded in the fluid. Experiments were conducted for two complex fluids: aqueous solutions of Carbopol and xanthan gum. On untreated glass surfaces, PIV demonstrates that both fluids experience a significant amount of effective slip. The experiments were repeated on glass that had been treated to feature positive surface charges, thereby promoting adhesion between the negatively charged polymeric constituents of the fluids and the glass surface. The Carbopol and xanthan gum droplets spread more slowly on the treated surface and to a smaller radial distance. PIV demonstrated that this reduced spreading was associated with a substantial reduction in slip. For Carbopol, the effective slip could be eliminated entirely to within the precision of the PIV measurements; the reduction in slip was less effective for xanthan gum, with a weak slip velocity remaining noticeable.

  10. SLIP CASTING METHOD

    Science.gov (United States)

    Allison, A.G.

    1959-09-01

    S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

  11. A Model for Low-Frequency Earthquake Slip

    Science.gov (United States)

    Chestler, S. R.; Creager, K. C.

    2017-12-01

    Using high-resolution relative low-frequency earthquake (LFE) locations, we calculate the patch areas (Ap) of LFE families. During episodic tremor and slip (ETS) events, we define AT as the area that slips during LFEs and ST as the total amount of summed LFE slip. Using observed and calculated values for AP, AT, and ST, we evaluate two end-member models for LFE slip within an LFE family patch. In the ductile matrix model, LFEs produce 100% of the observed ETS slip (SETS) in distinct subpatches (i.e., AT ≪ AP). In the connected patch model, AT = AP, but ST ≪ SETS. LFEs cluster into 45 LFE families. Spatial gaps (˜10 to 20 km) between LFE family clusters and smaller gaps within LFE family clusters serve as evidence that LFE slip is heterogeneous on multiple spatial scales. We find that LFE slip only accounts for ˜0.2% of the slip within the slow slip zone. There are depth-dependent trends in the characteristic (mean) moment and in the number of LFEs during both ETS events (only) and the entire ETS cycle (Mcets and NTets and Mcall and NTall, respectively). During ETS, Mc decreases with downdip distance but NT does not change. Over the entire ETS cycle, Mc decreases with downdip distance, but NT increases. These observations indicate that deeper LFE slip occurs through a larger number (800-1,200) of small LFEs, while updip LFE slip occurs primarily during ETS events through a smaller number (200-600) of larger LFEs. This could indicate that the plate interface is stronger and has a higher stress threshold updip.

  12. Middle Pleistocene infill of Hinkley Valley by Mojave River sediment and associated lake sediment: Depositional architecture and deformation by strike-slip faults

    Science.gov (United States)

    Miller, David; Haddon, Elizabeth; Langenheim, Victoria; Cyr, Andrew J.; Wan, Elmira; Walkup, Laura; Starratt, Scott W.

    2018-01-01

    avulsed through the valley, rather than continuing toward Lake Manix, during the late Pleistocene. Two dextral strike-slip fault zones, the Lockhart and the Mt. General, fold and displace the distinctive stratigraphic units, as well as surficial late Pleistocene and Holocene deposits. The sedimentary architecture and the two fault zones provide a framework for evaluating groundwater flow in Hinkley Valley.

  13. Direct measurement of wall slip and slip layer thickness of non-Brownian hard-sphere suspensions in rectangular channel flows

    Science.gov (United States)

    Jesinghausen, Steffen; Weiffen, Rene; Schmid, Hans-Joachim

    2016-09-01

    Wall slip is a long-known phenomenon in the field of rheology. Nevertheless, the origin and the evolution are not completely clear yet. Regarding suspensions, the effect becomes even more complicated, because different mechanisms like pure slip or slip due to particle migration have to be taken into account. Furthermore, suspensions themselves show many flow anomalies and the isolation of slip is complicated. In order to develop working physical models, further insight is necessary. In this work, we measured experimentally the wall slip velocities of different highly filled suspensions in a rectangular slit die directly with respect to the particle concentration and the particle size. The slip velocities were obtained using a particle image velocimetry (PIV) system. The suspensions consisting of a castor oil-cinnamon oil blend and PMMA particles were matched in terms of refractive indexes to appear transparent. Hereby, possible optical path lengths larger than 15 mm were achieved. The slip velocities were found to be in a quadratic relation to the wall shear stress. Furthermore, the overall flow rate as well as the particle concentration has a direct influence on the slip. Concerning the shear stress, there seem to be two regions of slip with different physical characteristics. Furthermore, we estimated the slip layer thickness directly from the velocity profiles and propose a new interpretation. The PIV technique is used to investigate the viscosity and implicit the concentration profile in the slit die. It is shown that the particle migration process is quite fast.

  14. Pseudodynamic Source Characterization for Strike-Slip Faulting Including Stress Heterogeneity and Super-Shear Ruptures

    KAUST Repository

    Mena, B.

    2012-08-08

    Reliable ground‐motion prediction for future earthquakes depends on the ability to simulate realistic earthquake source models. Though dynamic rupture calculations have recently become more popular, they are still computationally demanding. An alternative is to invoke the framework of pseudodynamic (PD) source characterizations that use simple relationships between kinematic and dynamic source parameters to build physically self‐consistent kinematic models. Based on the PD approach of Guatteri et al. (2004), we propose new relationships for PD models for moderate‐to‐large strike‐slip earthquakes that include local supershear rupture speed due to stress heterogeneities. We conduct dynamic rupture simulations using stochastic initial stress distributions to generate a suite of source models in the magnitude Mw 6–8. This set of models shows that local supershear rupture speed prevails for all earthquake sizes, and that the local rise‐time distribution is not controlled by the overall fault geometry, but rather by local stress changes on the faults. Based on these findings, we derive a new set of relations for the proposed PD source characterization that accounts for earthquake size, buried and surface ruptures, and includes local rise‐time variations and supershear rupture speed. By applying the proposed PD source characterization to several well‐recorded past earthquakes, we verify that significant improvements in fitting synthetic ground motion to observed ones is achieved when comparing our new approach with the model of Guatteri et al. (2004). The proposed PD methodology can be implemented into ground‐motion simulation tools for more physically reliable prediction of shaking in future earthquakes.

  15. Slip-dependent weakening on shallow plate boundary fault in the Japan subduction zone: shallow coseismic slip facilitated by foreshock afterslip

    Science.gov (United States)

    Ito, Yoshi; Ikari, Matt; Ujiie, Kohtaro; Kopf, Achim

    2017-04-01

    Understanding of role of slow earthquakes as they relate to the occurrence of both megathrust earthquakes and tsunami earthquakes is necessary to mitigate these disasters in the near future. Laboratory shearing experiments is one of important approach to evaluate these relationships. Here, we use powdered gouge samples from JFAST (IODP Expedition 343) Hole C0019E, core sample 17R-1, which is the plate boundary fault zone in the Japan Trench subduction zone. In this region, both large coseismic slip during the 2011 Tohoku-Oki earthquake as well as discrete slow slip events (SSE) have occurred. Experiments were conducted in a single-direct shear apparatus under normal stress of 16 MPa, with total shear displacements of up to 16 mm. We evaluate the slip-dependence of friction by extracting the velocity-dependent friction parameters a, b, and Dc , and also measure the rate of change in friction coefficient with shear displacement as the slip-dependence of friction. We report that in friction experiments using the Tohoku fault zone samples, an increase in sliding velocity exceeding that of earthquake afterslip can induce a change from steady-state frictional strength or slip hardening friction to slip-weakening frictional behavior. Our results show that the slip weakening is observed when the slip velocity exceeds 3.7 × 10-6 m/s during our experiments, while steady-state frictional strength or slip hardening is observed below 1 × 10-6 m/s. In the Japan Trench region, two slow events prior to the mainshock were observed in the mainshock area with a coseismic slip exceeding 30 m . One event is an episodic SSE with a slip velocity of 0.1 × 10-6 , and the other is afterslip after the largest Tohoku earthquake foreshock with a slip velocity exceeding 2 × 10-6 m/s. Our experiments show that slip-weakening friction should be expected at the afterslip rate, suggesting that the afterslip may have facilitated the large coseismic slip during the mainshock on the plate boundary

  16. Paleoseismic evidence of characteristic slip on the Western segment of the North Anatolian fault, Turkey

    Science.gov (United States)

    Klinger, Yann; Sieh, K.; Altunel, E.; Akoglu, A.; Barka, A.; Dawson, Tim; Gonzalez, Tania; Meltzner, A.; Rockwell, Thomas

    2003-01-01

    We have conducted a paleoseismic investigation of serial fault rupture at one site along the 110-km rupture of the North Anatolian fault that produced the Mw 7.4 earthquake of 17 August 1999. The benefit of using a recent rupture to compare serial ruptures lies in the fact that the location, magnitude, and slip vector of the most recent event are all very well documented. We wished to determine whether or not the previous few ruptures of the fault were similar to the recent one. We chose a site at a step-over between two major strike-slip traces, where the principal fault is a normal fault. Our two excavations across the 1999 rupture reveal fluvial sands and gravels with two colluvial wedges related to previous earthquakes. Each wedge is about 0.8 m thick. Considering the processes of collapse and subsequent diffusion that are responsible for the formation of a colluvial wedge, we suggest that the two paleoscarps were similar in height to the 1999 scarp. This similarity supports the concept of characteristic slip, at least for this location along the fault. Accelerator mass spectrometry (AMS) radiocarbon dates of 16 charcoal samples are consistent with the interpretation that these two paleoscarps formed during large historical events in 1509 and 1719. If this is correct, the most recent three ruptures at the site have occurred at 210- and 280-year intervals.

  17. PROCESSING OF CONCENTRATED AQUEOUS ZIRCONIA-BIOGLASS SLIPS BY SLIP CASTING

    Directory of Open Access Journals (Sweden)

    Beltina Leon

    2017-03-01

    Full Text Available 3 mol% yttria-partially stabilized zirconia (Y-TZP powder and a sol-gel derived CaO- P₂O₅- SiO₂ (64S bioglass, were used to produce Y-TZP- bioglass slip cast compacts. The rheological properties of concentrated aqueous Y-TZP- 64S suspensions prepared with two different glass contents: 10.5 vol% and 19.9 vol%, and ammonium polyacrylate (NH₄PA as dispersant, were investigated and compared with those of Y-TZP. The density of green cast samples was related to the degree of slip dispersion. The substitution of Y-TZP by 64S glass in the mixtures resulted in greater adsorption of NH₄PA; however, the viscosity and yield stress values of Y-TZP-64S slips were higher than those of Y-TZP ones for the solid loadings studied. The increase in the glass content from 10.5 to 19.9 vol% increased the viscosity and yield stress values. The presence of 64S glass in the mixtures resulted in a less dense packing of cast samples.

  18. Effects of three-dimensional crustal structure and smoothing constraint on earthquake slip inversions: Case study of the Mw6.3 2009 L'Aquila earthquake

    KAUST Repository

    Gallovič, František; Imperatori, Walter; Mai, Paul Martin

    2015-01-01

    Earthquake slip inversions aiming to retrieve kinematic rupture characteristics typically assume 1-D velocity models and a flat Earth surface. However, heterogeneous nature of the crust and presence of rough topography lead to seismic scattering and other wave propagation phenomena, introducing complex 3-D effects on ground motions. Here we investigate how the use of imprecise Green's functions - achieved by including 3-D velocity perturbations and topography - affect slip-inversion results. We create sets of synthetic seismograms, including 3-D heterogeneous Earth structure and topography, and then invert these synthetics using Green's functions computed for a horizontally layered 1-D Earth model. We apply a linear inversion, regularized by smoothing and positivity constraint, and examine in detail how smoothing effects perturb the solution. Among others, our tests and resolution analyses demonstrate how imprecise Green's functions introduce artificial slip rate multiples especially at shallow depths and that the timing of the peak slip rate is hardly affected by the chosen smoothing. The investigation is extended to recordings of the 2009 Mw6.3 L'Aquila earthquake, considering both strong motion and high-rate GPS stations. We interpret the inversion results taking into account the lessons learned from the synthetic tests. The retrieved slip model resembles previously published solutions using geodetic data, showing a large-slip asperity southeast of the hypocenter. In agreement with other studies, we find evidence for fast but subshear rupture propagation in updip direction, followed by a delayed propagation along strike. We conjecture that rupture was partially inhibited by a deep localized velocity-strengthening patch that subsequently experienced afterslip.

  19. Inorganic glass ceramic slip rings

    Science.gov (United States)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  20. Tectonic inversion in the Wandel Sea Basin

    DEFF Research Database (Denmark)

    Svennevig, Kristian; Guarnieri, Pierpaolo; Stemmerik, Lars

    2016-01-01

    Sheet and an upper Hondal Elv Thrust Sheet separated by a subhorizontal fault: the Central Detachment. The style of deformation and the structures described are interpreted as the result of Paleocene-Eocene N-S directed compression resulting in basin inversion with strike-slip faults only having minor...

  1. The role of water in slip casting

    Science.gov (United States)

    Mccauley, R. A.; Phelps, G. W.

    1984-01-01

    Slips and casting are considered in terms of physical and colloidal chemistry. Casting slips are polydisperse suspensions of lyophobic particles in water, whose degree of coagulation is controlled by interaction of flocculating and deflocculating agents. Slip casting rate and viscosity are functions of temperature. Slip rheology and response to deflocculating agents varies significantly as the kinds and amounts of colloid modifiers change. Water is considered as a raw material. Various concepts of water/clay interactions and structures are discussed. Casting is a de-watering operation in which water moves from slip to cast to mold in response to a potential energy termed moisture stress. Drying is an evaporative process from a free water surface.

  2. Evidence for Truncated Exponential Probability Distribution of Earthquake Slip

    KAUST Repository

    Thingbaijam, Kiran Kumar; Mai, Paul Martin

    2016-01-01

    Earthquake ruptures comprise spatially varying slip on the fault surface, where slip represents the displacement discontinuity between the two sides of the rupture plane. In this study, we analyze the probability distribution of coseismic slip, which provides important information to better understand earthquake source physics. Although the probability distribution of slip is crucial for generating realistic rupture scenarios for simulation-based seismic and tsunami-hazard analysis, the statistical properties of earthquake slip have received limited attention so far. Here, we use the online database of earthquake source models (SRCMOD) to show that the probability distribution of slip follows the truncated exponential law. This law agrees with rupture-specific physical constraints limiting the maximum possible slip on the fault, similar to physical constraints on maximum earthquake magnitudes.We show the parameters of the best-fitting truncated exponential distribution scale with average coseismic slip. This scaling property reflects the control of the underlying stress distribution and fault strength on the rupture dimensions, which determines the average slip. Thus, the scale-dependent behavior of slip heterogeneity is captured by the probability distribution of slip. We conclude that the truncated exponential law accurately quantifies coseismic slip distribution and therefore allows for more realistic modeling of rupture scenarios. © 2016, Seismological Society of America. All rights reserverd.

  3. Evidence for Truncated Exponential Probability Distribution of Earthquake Slip

    KAUST Repository

    Thingbaijam, Kiran K. S.

    2016-07-13

    Earthquake ruptures comprise spatially varying slip on the fault surface, where slip represents the displacement discontinuity between the two sides of the rupture plane. In this study, we analyze the probability distribution of coseismic slip, which provides important information to better understand earthquake source physics. Although the probability distribution of slip is crucial for generating realistic rupture scenarios for simulation-based seismic and tsunami-hazard analysis, the statistical properties of earthquake slip have received limited attention so far. Here, we use the online database of earthquake source models (SRCMOD) to show that the probability distribution of slip follows the truncated exponential law. This law agrees with rupture-specific physical constraints limiting the maximum possible slip on the fault, similar to physical constraints on maximum earthquake magnitudes.We show the parameters of the best-fitting truncated exponential distribution scale with average coseismic slip. This scaling property reflects the control of the underlying stress distribution and fault strength on the rupture dimensions, which determines the average slip. Thus, the scale-dependent behavior of slip heterogeneity is captured by the probability distribution of slip. We conclude that the truncated exponential law accurately quantifies coseismic slip distribution and therefore allows for more realistic modeling of rupture scenarios. © 2016, Seismological Society of America. All rights reserverd.

  4. EMG and Kinematic Responses to Unexpected Slips After Slip Training in Virtual Reality

    Science.gov (United States)

    Parijat, Prakriti; Lockhart, Thurmon E.

    2015-01-01

    The objective of the study was to design a virtual reality (VR) training to induce perturbation in older adults similar to a slip and examine the effect of the training on kinematic and muscular responses in older adults. Twenty-four older adults were involved in a laboratory study and randomly assigned to two groups (virtual reality training and control). Both groups went through three sessions including baseline slip, training, and transfer of training on slippery surface. The training group experienced twelve simulated slips using a visual perturbation induced by tilting a virtual reality scene while walking on the treadmill and the control group completed normal walking during the training session. Kinematic, kinetic, and EMG data were collected during all the sessions. Results demonstrated the proactive adjustments such as increased trunk flexion at heel contact after training. Reactive adjustments included reduced time to peak activations of knee flexors, reduced knee coactivation, reduced time to trunk flexion, and reduced trunk angular velocity after training. In conclusion, the study findings indicate that the VR training was able to generate a perturbation in older adults that evoked recovery reactions and such motor skill can be transferred to the actual slip trials. PMID:25296401

  5. A Model for Low-Frequency Earthquake Slip in Cascadia

    Science.gov (United States)

    Chestler, S.; Creager, K.

    2017-12-01

    Low-Frequency Earthquakes (LFEs) are commonly used to identify when and where slow slip occurred, especially for slow slip events that are too small to be observed geodetically. Yet, an understanding of how slip occurs within an LFE family patch, or patch on the plate interface where LFEs repeat, is limited. How much slip occurs per LFE and over what area? Do all LFEs within an LFE family rupture the exact same spot? To answer these questions, we implement a catalog of 39,966 LFEs, sorted into 45 LFE families, beneath the Olympic Peninsula, WA. LFEs were detected and located using data from approximately 100 3-component stations from the Array of Arrays experiment. We compare the LFE family patch area to the area within the LFE family patch that slips through LFEs during Cascadia Episodic Tremor and Slip (ETS) events. Patch area is calculated from relative LFE locations, solved for using the double difference method. Slip area is calculated from the characteristic moment (mean of the exponential moment-frequency distribution) and number LFEs for each family and geodetically measured ETS slip. We find that 0.5-5% of the area within an LFE family patch slips through LFEs. The rest must deform in some other manner (e.g., ductile deformation). We also explore LFE slip patterns throughout the entire slow slip zone. Is LFE slip uniform? Does LFE slip account for all geodetically observed slow slip? Double difference relocations reveal that LFE families are 2 km patches where LFE are clustered close together. Additionally, there are clusters of LFE families with diameters of 4-15 km. There are gaps with no observable, repeating LFEs between LFE families in clusters and between clusters of LFE families. Based on this observation, we present a model where LFE slip is heterogeneous on multiple spatial scales. Clusters of LFE families may represent patches with higher strength than the surrounding areas. Finally, we find that LFE slip only accounts for a small fraction ( 0

  6. Pedestrians in wintertime-effects of using anti-slip devices.

    Science.gov (United States)

    Berggård, Glenn; Johansson, Charlotta

    2010-07-01

    Pedestrians slipping and falling is a major safety problem around the world, not least in countries with long winters such as Sweden. About 25000-30000 people need medical care every year for treatment of fall injuries in Sweden. Use of appropriate shoes and anti-slip devices are examples of individual measures that have been suggested to prevent slipping and falling. An intervention study was performed during the period February to April 2008. The study, which focused on healthy adults in northern Sweden, examined the effect of using anti-slip devices on daily walking journeys and prevention of slip and falls. The respondents were divided into three groups: an Intervention Group, a Control Group, with similar distribution of gender and age, and a Comparison Group. Four questionnaires were distributed: (1) background, (2) daily diary of distance walked and occurrence of incidents or accidents reported weekly, (3) detailed incident or fall report and (4) experiences of using anti-slip devices for those who used these devices during the trial period. Half of the respondents stated that they had previous experience of using anti-slip devices. In this study, 52% of the respondents used anti-slip devices. Anti-slip devices improve the walking capability during wintertime. Among those using appropriate anti-slip devices, the average daily walking distance was found to be statistically significantly longer compared to people not using anti-slip devices. This study indicates that an increase in daily walking distance can be made without increasing the risk of slips/falls when using anti-slip devices. The study also indicates that by using appropriate anti-slip devices and having information about when and where to use them, based on their design, people avoid having slips and falls. The respondents experienced in using anti-slip devices in this study will continue to use them and will also recommend others to use anti-slip devises. Copyright 2010 Elsevier Ltd. All rights

  7. Duration of slip-resistant shoe usage and the rate of slipping in limited-service restaurants: results from a prospective and crossover study.

    Science.gov (United States)

    Verma, Santosh K; Zhao, Zhe; Courtney, Theodore K; Chang, Wen-Ruey; Lombardi, David A; Huang, Yueng-Hsiang; Brennan, Melanye J; Perry, Melissa J

    2014-01-01

    Several studies have indicated that slip-resistant shoes may have a positive effect on reducing the risk of slips and falls, a leading cause of injury at work. Few studies, however, have examined how duration of shoe usage affects their slip-resistance properties. This study examined the association between the duration of slip-resistant shoes usage and the self-reported rate of slipping in limited-service restaurant workers. A total of 475 workers from 36 limited-service restaurants in the USA were recruited to participate in a 12-week prospective study of workplace slipping. Of the 475 participants, 83 reported changing to a new pair of shoes at least once during the 12-week follow-up. The results show that slip-resistant shoes worn for less than six months were moderately more effective than those worn for more than six months. Changing to a new pair of shoes among those wearing slip-resistant shoes at baseline was associated with a 55% reduction in the rate of slipping (RR = 0.45, 95% CI = 0.23-0.89). Further research is needed to develop criteria for the replacement of slip-resistant shoes.

  8. Closed central slip injuries--a missed diagnosis?

    LENUS (Irish Health Repository)

    Nugent, N

    2011-09-01

    The extensor apparatus of the finger is a complex structure and injury can lead to significant digital dysfunction. Closed central slip injuries may be missed or diagnosis delayed because of lack of an open wound and often no radiographic abnormality, and can result in boutonniere deformities if untreated. This study aimed to quantify the number of patients attending with closed central slip injuries and to ascertain if the initial diagnosis was correct. The number of patients presenting to us over a 6 month period was recorded. The original diagnosis, time to diagnosis of central slip injury and the presence\\/absence of a boutonniere deformity were recorded. Ten patients were included in the study. Seven (70%) injuries were due to sport. Eight (80%) had a delayed diagnosis of central slip injury. Six (60%) had previously presented to general practitioners or emergency departments. Seven (70%) had boutonniere deformities. Closed central slip injuries can be missed. Simple clinical tests can diagnose central slip disruption.

  9. Variable slip-rate and slip-per-event on a plate boundary fault: The Dead Sea fault in northern Israel

    Science.gov (United States)

    Wechsler, Neta; Rockwell, Thomas K.; Klinger, Yann

    2018-01-01

    We resolved displacement on buried stream channels that record the past 3400 years of slip history for the Jordan Gorge (JGF) section of the Dead Sea fault in Israel. Based on three-dimensional (3D) trenching, slip in the past millennium amounts to only 2.7 m, similar to that determined in previous studies, whereas the previous millennium experienced two to three times this amount of displacement with nearly 8 m of cumulative slip, indicating substantial short term variations in slip rate. The slip rate averaged over the past 3400 years, as determined from 3D trenching, is 4.1 mm/yr, which agrees well with geodetic estimates of strain accumulation, as well as with longer-term geologic slip rate estimates. Our results indicate that: 1) the past 1200 years appear to significantly lack slip, which may portend a significant increase in future seismic activity; 2) short-term slip rates for the past two millennia have varied by more than a factor of two and suggest that past behavior is best characterized by clustering of earthquakes. From these observations, the earthquake behavior of the Jordan Gorge fault best fits is a "weak segment model" where the relatively short fault section (20 km), bounded by releasing steps, fails on its own in moderate earthquakes, or ruptures with adjacent segments.

  10. High-Precision Locations and the Stress Field from Instrumental Seismicity, Moment Tensors, and Short-Period Mechanisms through the Mina Deflection, Central Walker Lane

    Science.gov (United States)

    Ruhl, C. J.; Smith, K. D.

    2012-12-01

    The Mina Deflection (MD) region of the central Walker Lane of eastern California and western Nevada, is a complex zone of northeast-trending normal, and primarily left-lateral strike-slip to oblique-slip faulting that separates the Southern Walker Lane (SWL) from a series of east-tilted normal fault blocks in the Central Walker Lane (CWL) (Faulds and Henry, 2008; Surpless, 2008). The MD accommodates the transfer of right-lateral strike-slip motion from northwest-striking faults in the SWL to a series of left-stepping northwest-striking right-lateral strike-slip faults in the CWL, east of the Wassuk Range near Hawthorne, NV. The ~50 km wide ~80 km long right-step is a distinct transition in regional physiography that has been attributed to strain accommodation through pre-Cenozoic lithospheric structures. Several slip transfer mechanisms have been proposed within the MD, from clockwise rotation of high-angle fault blocks (Wesnousky, 2005), to low-angle displacement within the Silver Peak-Lone Mountain complex (Oldow et al., 2001), and curved fault arrays associated with localized basins and tectonic depressions (Ferranti et al., 2009). The region has been a regular source of M4+ events, the most recent being an extended sequence that included twenty-seven M 3.5+ earthquakes (largest event M 4.6) south of Hawthorne in 2011. These earthquakes (Mina, NV, and the 1932 M 7.1 Cedar Mountains earthquake east of the Pilot Mountains. Another persistent feature in the seismicity is an ~40 km long arcuate distribution of activity extending from approximately Queen Valley, north of the White Mountains, to Mono Lake that appears to reflect a southwestern boundary to northeast-striking structures in the MD. Here we develop high-precision relocations of instrumental seismicity in the MD from 1984 through 2012, including relocations of the 2004 sequence, and account for the historical seismic record. MT solutions from published reports and computed from recent M 3.5+ earthquakes as

  11. Slipped capital femoral epiphysis: A modern treatment protocol

    Directory of Open Access Journals (Sweden)

    Slavković Nemanja

    2009-01-01

    Full Text Available The treatment of a patient with slipped capital femoral epiphysis begins with an early diagnosis and accurate classification. On the basis of symptom duration, clinical findings and radiographs, slipped capital femoral epiphysis is classified as pre-slip, acute, acute-on-chronic and chronic. The long-term outcome of slipped capital femoral epiphysis is directly related to severity and the presence or absence of avascular necrosis and/or chondrolysis. Therefore, the first priority in the treatment of slipped capital femoral epiphysis is to avoid complications while securing the epiphysis from further slippage. Medical treatment of patients with acute and acute-on-chronic slipped capital femoral epiphysis, as well as those presented in pre-slip stage, is the safest, although time-consuming. Manipulations, especially forced and repeated, are not recommended due to higher avascular necrosis risk. The use of intraoperative fluoroscopy to assist in the placement of internal fixation devices has markedly increased the success of surgical treatment. Controversy remains as to whether the proximal femoral epiphysis in severe, chronic slipped capital femoral epiphysis should be realigned by extracapsular osteotomies or just fixed in situ. The management protocol for slipped capital femoral epiphysis depends on the experience of the surgeon, motivation of the patient and technical facilities.

  12. Re-investigation of slip rate along the southern part of the Sumatran Fault Zone using SuMo GPS network

    Science.gov (United States)

    Hermawan, I.; Lubis, A. M.; Sahputra, R.; Hill, E.; Sieh, K.; Feng, L.; Salman, R.; Hananto, N.

    2015-12-01

    The Sumatran Fault Zone (SFZ) accommodates a significant component of the strike-slip motion of oblique convergence along the Sumatra subduction zone. Previous studies have suggested that the slip rates of the SFZ increase from south to north. However, recent work shows that the slip rates may not vary along the SFZ [Bradley et al., 2015]. New data are needed to help confirm these results, and to assess slip-rate variability and fault segmentation in more detail. This information is vital for seismic hazard assessment for the region. We have therefore installed and operated the SuMo (Sumatran Fault Monitoring) network, a dense GPS campaign network focused around the SFZ. From 2013-2015 we selected and installed 32 GPS monuments over the southern part of the SFZ. The network comprises of three transects. The first transect is around the location of the great 1900 earthquake, at the Musi segment. Two transects cover the Manna segment, which saw its last great earthquake in 1893, and the Kumering segment, which saw two great earthquakes in 1933 (M 7.5) and 1994 (M 7.0). We have now conducted three GPS campaign surveys for these stations (3-4 days of measurement for each occupation site), and established 5 semi-permanent cGPS stations in the area. The processed data show that the campaigns sites are still too premature to be used for estimating slip rates, but from the preliminary results for the semi-permanent stations we may see our first signal of deformation. More data from future survey campaigns will help us to estimated revised slip rates. In addition to the science goals for our project, we are this year starting a project called "SuMo Goes to School," which will aim to disseminate information on our science to the schools that house the SuMo GPS stations. The SuMo project also achieves capacity building by training students from Bengkulu University in geodesy and campaign GPS survey techniques.

  13. KINEMATICS AND DYNAMICS OF BALLS WHILE BEING POLISHED BETWEEN MISALIGNED DISKS IN DRIVEN SEPARATOR

    Directory of Open Access Journals (Sweden)

    K. G. Schetnikovich

    2007-01-01

    Full Text Available The paper contains description of tool design which is used for rough polishing of balls made of brittle materials. This tool consists of top disk, which is fi-eely set on pouring bearing of the separator shaft, and a bottom disk with elastic coating. Theoretical investigations of ball kinematics have permitted to determine an angular velocity of the balls in the machining zone, value and direction oi slipping speed with respect to the tool.it has been determined that even change of the position of bail rotation instantaneous axis relative to the separator is reached at equality of angular velocities of the bottom disk and the separator. When the top disk is freely set slipping speed is equal for all the balls of the machined lot. When the top disk is stationary slipping speed is significantly increasing however its value becomes variable and depends on ball distance to separator rotation axis.The presented equations of ball dynamics in the machining zone have made it possible to detennine a cohesive force with the bottom disk, frictional forces against the top disk and separator. Recommendations on selection of machining modes at initial and final stages of ball polishing are given in the paper.

  14. Three Types of Flower Structures in a Divergent-Wrench Fault Zone

    Science.gov (United States)

    Huang, Lei; Liu, Chi-yang

    2017-12-01

    Flower structures are typical features of wrench fault zones. In conventional studies, two distinct kinds of flower structures have been identified based on differences in their internal structural architecture: (1) negative flower structures characterized by synforms and normal separations and (2) positive flower structures characterized by antiforms and reverse separations. In addition to negative and positive flower structures, in this study, a third kind of flower structure was identified in a divergent-wrench fault zone, a hybrid characterized by both antiforms and normal separations. Negative flower structures widely occur in divergent-wrench fault zones, and their presence indicates the combined effects of extensional and strike-slip motion. In contrast, positive and hybrid flower structures occur only in fault restraining bends and step overs. A hybrid flower structure can be considered as product of a kind of structural deformation typical of divergent-wrench zones; it is the result of the combined effects of extensional, compressional, and strike-slip strains under a locally appropriate compressional environment. The strain situation in it represents the transition stage that in between positive and negative flower structures. Kinematic and dynamic characteristics of the hybrid flower structures indicate the salient features of structural deformation in restraining bends and step overs along divergent-wrench faults, including the coexistence of three kinds of strains (i.e., compression, extension, and strike-slip) and synchronous presence of compressional (i.e., typical fault-bend fold) and extensional (normal faults) deformation in the same place. Hybrid flower structures are also favorable for the accumulation of hydrocarbons because of their special structural configuration in divergent-wrench fault zones.

  15. Effects of three-dimensional crustal structure and smoothing constraint on earthquake slip inversions: Case study of the Mw6.3 2009 L'Aquila earthquake

    KAUST Repository

    Gallovič, František

    2015-01-01

    Earthquake slip inversions aiming to retrieve kinematic rupture characteristics typically assume 1-D velocity models and a flat Earth surface. However, heterogeneous nature of the crust and presence of rough topography lead to seismic scattering and other wave propagation phenomena, introducing complex 3-D effects on ground motions. Here we investigate how the use of imprecise Green\\'s functions - achieved by including 3-D velocity perturbations and topography - affect slip-inversion results. We create sets of synthetic seismograms, including 3-D heterogeneous Earth structure and topography, and then invert these synthetics using Green\\'s functions computed for a horizontally layered 1-D Earth model. We apply a linear inversion, regularized by smoothing and positivity constraint, and examine in detail how smoothing effects perturb the solution. Among others, our tests and resolution analyses demonstrate how imprecise Green\\'s functions introduce artificial slip rate multiples especially at shallow depths and that the timing of the peak slip rate is hardly affected by the chosen smoothing. The investigation is extended to recordings of the 2009 Mw6.3 L\\'Aquila earthquake, considering both strong motion and high-rate GPS stations. We interpret the inversion results taking into account the lessons learned from the synthetic tests. The retrieved slip model resembles previously published solutions using geodetic data, showing a large-slip asperity southeast of the hypocenter. In agreement with other studies, we find evidence for fast but subshear rupture propagation in updip direction, followed by a delayed propagation along strike. We conjecture that rupture was partially inhibited by a deep localized velocity-strengthening patch that subsequently experienced afterslip.

  16. Stick-slip substructure in rapid tape peeling

    KAUST Repository

    Thoroddsen, Sigurdur T.

    2010-10-15

    The peeling of adhesive tape is known to proceed with a stick-slip mechanism and produces a characteristic ripping sound. The peeling also produces light and when peeled in a vacuum, even X-rays have been observed, whose emissions are correlated with the slip events. Here we present direct imaging of the detachment zone when Scotch tape is peeled off at high speed from a solid surface, revealing a highly regular substructure, during the slip phase. The typical 4-mm-long slip region has a regular substructure of transverse 220 μm wide slip bands, which fracture sideways at speeds over 300 m/s. The fracture tip emits waves into the detached section of the tape at ∼100 m/s, which promotes the sound, so characteristic of this phenomenon.

  17. Stick-slip substructure in rapid tape peeling

    KAUST Repository

    Thoroddsen, Sigurdur T; Nguyen, H. D.; Takehara, K.; Etoh, T. G.

    2010-01-01

    The peeling of adhesive tape is known to proceed with a stick-slip mechanism and produces a characteristic ripping sound. The peeling also produces light and when peeled in a vacuum, even X-rays have been observed, whose emissions are correlated with the slip events. Here we present direct imaging of the detachment zone when Scotch tape is peeled off at high speed from a solid surface, revealing a highly regular substructure, during the slip phase. The typical 4-mm-long slip region has a regular substructure of transverse 220 μm wide slip bands, which fracture sideways at speeds over 300 m/s. The fracture tip emits waves into the detached section of the tape at ∼100 m/s, which promotes the sound, so characteristic of this phenomenon.

  18. Transcurrencia a lo largo de la Falla Sierra de Varas (Sistema de fallas de la Cordillera de Domeyko, norte de Chile Strike-slip along the Sierra de Varas Fault (Cordillera de Domeyko Fault-System, northern Chile

    Directory of Open Access Journals (Sweden)

    Hans Niemeyer

    2009-01-01

    Aguada del Hornito-Aguada del Cerro Alto de Varas segment. Upper Paleozoic granitoids of the same composition, internal structure and age were cut and displaced by the fault. A sinistral horizontal separation of 15.6±1 kmwitha vertical componentof 4.9±0.1 km, suggests a sinistral-reverse net displacement of 16.4±1 km. Thisis consistent with the local stratigraphic section that was eroded from the eastern block. A kinematic and dynamic analysis of mesofaults spatially related to the SVF displacements was conducted to identify the different fault populations and to obtain the stress tensor. Two structural systems were identified: an early reverse-strike-slip system and a late dextral superposed system. The first one ocurred during late middle Eocene, and the second is post-Miocene with an horizontal displacement of 0.6 km. The presence of coeval strike-slip displacements along the Sierra de Varas Fault and reverse displacements in a 'reverse flower' in the studied segment show that the structural evolution of the Sierra de Varas was dominated by a bulk transpression during the late middle Eocene. The left-lateral displacement here demonstrated for the Sierra de Varas Fault and its inflection to the SE, south of the Aguada del Cerro Alto de Varas are compatible with the westward vergence of the folds and reverse faults in the El Profeta fault-and-thrust belt, which should be also the result of the transpression.

  19. Modeling of rock friction 2. Simulation of preseismic slip

    International Nuclear Information System (INIS)

    Dieterich, J.H.

    1979-01-01

    The constitutive relations developed in the companion paper are used to model detailed observations of preseismic slip and the onset of unstable slip in biaxial laboratory experiments. The simulations employ a deterministic plane strain finite element model to represent the interactions both within the sliding blocks and between the blocks and the loading apparatus. Both experiments and simulations show that preseismic slip controlled by initial inhomogeneity of shear stress along the sliding surface relative to the frictional strength. As a consequence of the inhomogeneity, stable slip begins at a point on the surface and the area of slip slowly expands as the external loading increases. A previously proposed correlation between accelerating rates of stable slip and growth of the area of slip is supported by the simulations. In the simulations and in the experiments, unstable slip occurs, shortly after a propagating slip event traverses the sliding surface and breaks out at the ends of the sample. In the model the breakout of stable slip causes a sudden acceleration of slip rates. Because of velocity dependency of the constitutive relationship for friction, the rapid acceleration of slip causes a decrease in frictional strength. Instability occurs when the frictional strength decreases with displacement at a rate that exceeds the intrinsic unloading characteristics of the sample and test machine. A simple slider-spring model that does not consider preseismic slip appears to approximate the transition adequately from stable sliding to unstable slip as a function of normal stress machine stiffness, and surface roughness for small samples. However, for large samples and for natural faults the simulations suggest that the simple model may be inaccurate because it does not take into account potentially large preseismic displacements that will alter the friction parameters prior to instability

  20. Fluvial-Deltaic Strata as a High-Resolution Recorder of Fold Growth and Fault Slip

    Science.gov (United States)

    Anastasio, D. J.; Kodama, K. P.; Pazzaglia, F. P.

    2008-12-01

    Fluvial-deltaic systems characterize the depositional record of most wedge-top and foreland basins, where the synorogenic stratigraphy responds to interactions between sediment supply driven by tectonic uplift, climate modulated sea level change and erosion rate variability, and fold growth patterns driven by unsteady fault slip. We integrate kinematic models of fault-related folds with growth strata and fluvial terrace records to determine incremental rates of shortening, rock uplift, limb tilting, and fault slip with 104-105 year temporal resolution in the Pyrenees and Apennines. At Pico del Aguila anticline, a transverse dècollement fold along the south Pyrenean mountain front, formation-scale synorogenic deposition and clastic facies patterns in prodeltaic and slope facies reflect tectonic forcing of sediment supply, sea level variability controlling delta front position, and climate modulated changes in terrestrial runoff. Growth geometries record a pinned anticline and migrating syncline hinges during folding above the emerging Guarga thrust sheet. Lithologic and anhysteretic remanent magnetization (ARM) data series from the Eocene Arguis Fm. show cyclicity at Milankovitch frequencies allowing detailed reconstruction of unsteady fold growth. Multiple variations in limb tilting rates from roof ramp and basal dècollement. Along the northern Apennine mountain front, the age and geometry of strath terraces preserved across the Salsomaggiore anticline records the Pleistocene-Recent kinematics of the underlying fault-propagation fold as occurring with a fixed anticline hinge, a rolling syncline hinge, and along-strike variations in uplift and forelimb tilting. The uplifted intersection of terrace deposits documents syncline axial surface migration and underlying fault-tip propagation at a rate of ~1.4 cm/yr since the Middle Pleistocene. Because this record of fault slip coincides with the well-known large amplitude oscillations in global climate that contribute

  1. Slip reactivation during the 2011 Tohoku earthquake: Dynamic rupture and ground motion simulations

    Science.gov (United States)

    Galvez, P.; Dalguer, L. A.

    2013-12-01

    The 2011 Mw9 Tohoku earthquake generated such as vast geophysical data that allows studying with an unprecedented resolution the spatial-temporal evolution of the rupture process of a mega thrust event. Joint source inversion of teleseismic, near-source strong motion and coseismic geodetic data , e.g [Lee et. al, 2011], reveal an evidence of slip reactivation process at areas of very large slip. The slip of snapshots of this source model shows that after about 40 seconds the big patch above to the hypocenter experienced an additional push of the slip (reactivation) towards the trench. These two possible repeating slip exhibited by source inversions can create two waveform envelops well distinguished in the ground motion pattern. In fact seismograms of the KiK-Net Japanese network contained this pattern. For instance a seismic station around Miyagi (MYGH10) has two main wavefronts separated between them by 40 seconds. A possible physical mechanism to explain the slip reactivation could be a thermal pressurization process occurring in the fault zone. In fact, Kanamori & Heaton, (2000) proposed that for large earthquakes frictional melting and fluid pressurization can play a key role of the rupture dynamics of giant earthquakes. If fluid exists in a fault zone, an increase of temperature can rise up the pore pressure enough to significantly reduce the frictional strength. Therefore, during a large earthquake the areas of big slip persuading strong thermal pressurization may result in a second drop of the frictional strength after reaching a certain value of slip. Following this principle, we adopt for slip weakening friction law and prescribe a certain maximum slip after which the friction coefficient linearly drops down again. The implementation of this friction law has been done in the latest unstructured spectral element code SPECFEM3D, Peter et. al. (2012). The non-planar subduction interface has been taken into account and place on it a big asperity patch inside

  2. Slip activity of persistent slip bands in polycrystalline nickel

    International Nuclear Information System (INIS)

    Weidner, A.; Beyer, R.; Blochwitz, C.; Holste, C.; Schwab, A.; Tirschler, W.

    2006-01-01

    The appearance of glide localizations after cyclic deformation in the saturation stage was investigated for polycrystalline nickel. It was shown that persistent slip bands (PSBs) are formed in a wide range of grain orientations. Concerning the grain size it was found, that the probability for the appearance of PSBs is higher for larger grains. The local slip activity of the formed PSBs was studied after half-cycle deformation using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The fraction of grains with glide-active PSBs and the glide-active PSB volume itself is very small after the half-cycle loading. The obtained local shear strain amplitudes are quite high and vary in the range of 0.2-5%. They are comparable with those found in nickel single crystals at the same loading procedure

  3. Recent state of stress change in the Walker Lane zone, western Basin and Range province, United States

    Science.gov (United States)

    Bellier, Olivier; Zoback, Mary Lou

    1995-06-01

    The NW to north-trending Walker Lane zone (WLZ) is located along the western boundary of the northern Basin and Range province with the Sierra Nevada. This zone is distinguished from the surrounding Basin and Range province on the basis of irregular topography and evidence for both normal and strike-slip Holocene faulting. Inversion of slip vectors from active faults, historic fault offsets, and earthquake focal mechanisms indicate two distinct Quaternary stress regimes within the WLZ, both of which are characterized by a consistent WNW σ3 axis; these are a normal faulting regime with a mean σ3 axis of N85°±9°W and a mean stress ratio (R value) (R=(σ2-σ1)/(σ3-σ1)) of 0.63-0.74 and a younger strike-slip faulting regime with a similar mean σ3 axis (N65° - 70°W) and R values ranging between ˜ 0.1 and 0.2. This younger regime is compatible with historic fault offsets and earthquake focal mechanisms. Both the extensional and strike-slip stress regimes reactivated inherited Mesozoic and Cenozoic structures and also produced new faults. The present-day strike-slip stress regime has produced strike-slip, normal oblique-slip, and normal dip-slip historic faulting. Previous workers have explained the complex interaction of active strike-slip, oblique, and normal faulting in the WLZ as a simple consequence of a single stress state with a consistent WNW σ3 axis and transitional between strike-slip and normal faulting (maximum horizontal stress approximately equal to vertical stress, or R ≈ 0 in both regimes) with minor local fluctuations. The slip data reported here support previous results from Owens Valley that suggest deformation within temporally distinct normal and strike-slip faulting stress regimes with a roughly constant WNW trending σ3 axis (Zoback, 1989). A recent change from a normal faulting to a strike-slip faulting stress regime is indicated by the crosscutting striae on faults in basalts the dominantly strike-slip earthquake focal mechanisms and

  4. Women, transition and strikes in Serbia

    OpenAIRE

    Novaković, Nada G.

    2014-01-01

    The author, in a sociological way, describes and analyzes the concepts of transition, privatization and strikes in Serbia, particularly the place of women in it. It examines the most important economic and social causes and consequences of these phenomena. The main hypothesis is: women's strikes in the Serbian transition are less efficient than strikes and public protests of women in the developed world and the second Yugoslavia. A strike is a class conflict, in which the workers are fighting...

  5. Development of compact slip detection sensor using dielectric elastomer

    Science.gov (United States)

    Choi, Jae-young; Hwang, Do-Yeon; Kim, Baek-chul; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, Ja Choon

    2015-04-01

    In this paper, we developed a resistance tactile sensor that can detect a slip on the surface of sensor structure. The presented sensor device has fingerprint-like structures that are similar with the role of the humans finger print. The resistance slip sensor that the novel developed uses acrylo-nitrile butadiene rubber (NBR) as a dielectric substrate and graphene as an electrode material. We can measure the slip as the structure of sensor makes a deformation and it changes the resistance through forming a new conductive route. To manufacture our sensor, we developed a new imprint process. By using this process, we can produce sensor with micro unit structure. To verify effectiveness of the proposed slip detection, experiment using prototype of resistance slip sensor is conducted with an algorithm to detect slip and slip is successfully detected. We will discuss the slip detection properties.

  6. Electrical Potentials Observed During Frictional Stick-Slip - A Semiconductor Mechanism

    Science.gov (United States)

    Leeman, J.; Scuderi, M.; Marone, C.; Saffer, D. M.

    2013-12-01

    Electromagnetic phenomena are commonly reported during and after large earthquakes. Various lines of evidence including charring of plant roots, magnetic remnant signatures in pseudotachylite, and visible earthquake lights indicate a strong electrical potential separation during co-seismic rupture. Suggested explanations have included triboelectricity, piezoelectricity, and streaming potentials. The 'semiconductor effect', or migration of electron holes, has been proposed as an alternative explanation and studied extensively in solids. We present evidence of a similar migration effect in a granular material that exhibits repeated frictional stick-slip events under a variety of conditions. Soda-lime glass beads were sheared in a double-direct shear configuration in a biaxial loading frame. Glass beads exhibit consistent, repetitive stick-slip and rate/state friction effects that are similar to rock. Layers of 5 mm thickness were sheared under a constant normal load of 4MPa, at load point velocities of 1, 30, and 100 μm/s. This was done for mono-disperse particle size distributions of 100-150 μm and 420-500 μm. Tests were conducted at room humidity, at 100% humidity, and under submerged conditions. During shearing, the electrical potential of the surface was monitored relative to the system ground with a non-contact electrostatic volt meter (ESVM) manufactured by Trek Incorporated. During stick-slip events, we observe electrical potential anomalies that appear to be related to failure of force chains supporting the shear load. Two distinct types of behavior are delineated by the attainment of steady state frictional sliding. In the pre-steady state phase, as shear stress is increasing, layers are observed to charge during stick-slip and the potential of the entire system rises. When shear stress rises to the level of steady state frictional sliding, the system begins to discharge, with superimposed anomalies characterized by potential drops of several volts that

  7. The influence of slip velocity and temperature on permeability during and after high-velocity fault slip

    Science.gov (United States)

    Tanikawa, W.; Mukoyoshi, H.; Tadai, O.; Hirose, T.; Lin, W.

    2011-12-01

    Fluid transport properties in fault zones play an important role in dynamic processes during large earthquakes. If the permeability in a fault zone is low, high pore-fluid pressures caused by thermal pressurization (Sibson, 1973) or shear-induced compaction (Blanpied et al., 1992) can lead to an apparent reduction of fault strength. Changes in porosity and permeability of fault rocks within a fault zone during earthquakes and the subsequent progressive recovery of these properties may have a large influence on earthquake recurrence (Sleep and Blanpied, 1992). A rotary shear apparatus was used to investigate changes of fluid transport properties in a fault zone by real-time measurement of gas flow rates during and after shearing of hollow sandstone and granite cylinders at various slip rates. Our apparatus measures permeability parallel to the slip plane in both the slip zone and wall rocks. In all cases, permeability decreased rapidly with an increase of friction, but recovered soon after slip, reaching a steady state within several tens of minutes. The rate of reduction of permeability increased with increasing slip velocity. Permeability did not recover to pre-slip levels after low-velocity tests but recovered to exceed them after high-velocity tests. Frictional heating of gases at the slip surface increased gas viscosity, which increased gas flow rate to produce an apparent permeability increase. The irreversible permeability changes of the low-velocity tests were caused by gouge formation due to wearing and smoothing of the slip surface. The increase of permeability after high-velocity tests was caused by mesoscale fracturing in response to rapid temperature rise. Changes of pore fluid viscosity contributed more to changes of flow rate than did permeability changes caused by shear deformation, although test results from different rocks and pore fluids might be different. References Blanpied, M.L., Lockner, D.A., Byerlee, J.D., 1992. An earthquake mechanism

  8. Stress distribution of metatarsals during forefoot strike versus rearfoot strike: A finite element study.

    Science.gov (United States)

    Li, Shudong; Zhang, Yan; Gu, Yaodong; Ren, James

    2017-12-01

    Due to the limitations of experimental approaches, comparison of the internal deformation and stresses of the human man foot between forefoot and rearfoot landing is not fully established. The objective of this work is to develop an effective FE modelling approach to comparatively study the stresses and energy in the foot during forefoot strike (FS) and rearfoot strike (RS). The stress level and rate of stress increase in the Metatarsals are established and the injury risk between these two landing styles is evaluated and discussed. A detailed subject specific FE foot model is developed and validated. A hexahedral dominated meshing scheme was applied on the surface of the foot bones and skin. An explicit solver (Abaqus/Explicit) was used to stimulate the transient landing process. The deformation and internal energy of the foot and stresses in the metatarsals are comparatively investigated. The results for forefoot strike tests showed an overall higher average stress level in the metatarsals during the entire landing cycle than that for rearfoot strike. The increase rate of the metatarsal stress from the 0.5 body weight (BW) to 2 BW load point is 30.76% for forefoot strike and 21.39% for rearfoot strike. The maximum rate of stress increase among the five metatarsals is observed on the 1st metatarsal in both landing modes. The results indicate that high stress level during forefoot landing phase may increase potential of metatarsal injuries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A multilevel simulation approach to derive the slip boundary condition of the solid phase in two-fluid models

    Science.gov (United States)

    Feng, Zhi-Gang; Michaelides, Efstathios; Mao, Shaolin

    2011-11-01

    The simulation of particulate flows for industrial applications often requires the use of a two-fluid model (TFM), where the solid particles are considered as a separate continuous phase. One of the underlining uncertainties in the use of aTFM in multiphase computations comes from the boundary condition of the solid phase. The no-slip condition at a solid boundary is not a valid assumption for the solid phase. Instead, several researchers advocate a slip condition as a more appropriate boundary condition. However, the question on the selection of an exact slip length or a slip velocity coefficient is still unanswered. In the present work we propose a multilevel simulation approach to compute the slip length that is applicable to a TFM. We investigate the motion of a number of particles near a vertical solid wall, while the particles are in fluidization using a direct numerical simulation (DNS); the positions and velocities of the particles are being tracked and analyzed at each time step. It is found that the time- and vertical-space averaged values of the particle velocities converge, yielding velocity profiles that can be used to deduce the particle slip length close to a solid wall. This work was supported by a grant from the DOE-NETL (DE-NT0008064) and by a grant from NSF (HRD-0932339).

  10. Dynamical stability of slip-stacking particles

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, Jeffrey; Zwaska, Robert

    2014-09-01

    We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

  11. Foot-strike pattern and performance in a marathon.

    Science.gov (United States)

    Kasmer, Mark E; Liu, Xue-Cheng; Roberts, Kyle G; Valadao, Jason M

    2013-05-01

    To determine prevalence of heel strike in a midsize city marathon, if there is an association between foot-strike classification and race performance, and if there is an association between foot-strike classification and gender. Foot-strike classification (forefoot, midfoot, heel, or split strike), gender, and rank (position in race) were recorded at the 8.1-km mark for 2112 runners at the 2011 Milwaukee Lakefront Marathon. 1991 runners were classified by foot-strike pattern, revealing a heel-strike prevalence of 93.67% (n = 1865). A significant difference between foot-strike classification and performance was found using a Kruskal-Wallis test (P strike. No significant difference between foot-strike classification and gender was found using a Fisher exact test. In addition, subgroup analysis of the 126 non-heel strikers found no significant difference between shoe wear and performance using a Kruskal-Wallis test. The high prevalence of heel striking observed in this study reflects the foot-strike pattern of most mid-distance to long-distance runners and, more important, may predict their injury profile based on the biomechanics of a heel-strike running pattern. This knowledge can help clinicians appropriately diagnose, manage, and train modifications of injured runners.

  12. Motion of two spheres translating and rotating through a viscous fluid with slip surfaces

    International Nuclear Information System (INIS)

    Saad, E I

    2012-01-01

    The axisymmetrical motion of two spherical particles translating along and rotating about a common line that joins their centers in viscous fluid with slip flow boundary conditions on their surfaces has been studied numerically. The particles may differ in radius and in translational and angular velocities. Under the Stokesian approximation, a general solution is constructed from the superposition of the basic functions in the two spherical coordinate systems based on the centers of the particles. The boundary conditions at their surfaces are satisfied by the collocation technique. Numerical results for the normalized drag force and couple acting on each sphere are obtained for various values of the slip coefficients, size ratio, separation parameter, and velocity ratio of the particles. The normalized force and couple on each particle reach the single particle limit as the distance between the centers grows large enough and each particle may then be translated and rotated independently of each other. The accuracy of the numerical technique has been tested against the known analytical solution for two spheres with no-slip surfaces. (paper)

  13. Stochastic Wheel-Slip Compensation Based Robot Localization and Mapping

    Directory of Open Access Journals (Sweden)

    SIDHARTHAN, R. K.

    2016-05-01

    Full Text Available Wheel slip compensation is vital for building accurate and reliable dead reckoning based robot localization and mapping algorithms. This investigation presents stochastic slip compensation scheme for robot localization and mapping. Main idea of the slip compensation technique is to use wheel-slip data obtained from experiments to model the variations in slip velocity as Gaussian distributions. This leads to a family of models that are switched depending on the input command. To obtain the wheel-slip measurements, experiments are conducted on a wheeled mobile robot and the measurements thus obtained are used to build the Gaussian models. Then the localization and mapping algorithm is tested on an experimental terrain and a new metric called the map spread factor is used to evaluate the ability of the slip compensation technique. Our results clearly indicate that the proposed methodology improves the accuracy by 72.55% for rotation and 66.67% for translation motion as against an uncompensated mapping system. The proposed compensation technique eliminates the need for extro receptive sensors for slip compensation, complex feature extraction and association algorithms. As a result, we obtain a simple slip compensation scheme for localization and mapping.

  14. Sentinel-1 observation of the 2017 Sangsefid earthquake, northeastern Iran: Rupture of a blind reserve-slip fault near the Eastern Kopeh Dagh

    Science.gov (United States)

    Xu, Guangyu; Xu, Caijun; Wen, Yangmao

    2018-04-01

    New satellites are now revealing InSAR-based surface deformation within a week after natural hazard events. Quick hazard responses will be more publically accessible and provide information to responding agencies. Here we used Sentinel-1 interferometric synthetic aperture radar (InSAR) data to investigate coseismic deformation associated with the 2017 Sangsefid earthquake, which occurred in the southeast margin of the Kopeh Dagh fault system. The ascending and descending interferograms indicate thrust-dominated slip, with the maximum line-of-sight displacement of 10.5 and 13.7 cm, respectively. The detailed slip-distribution of the 2017 Sangsefid Mw6.1 earthquake inferred from geodetic data is presented here for the first time. Although the InSAR interferograms themselves do not uniquely constrain what the primary slip surface is, we infer that the source fault dips to southwest by analyzing the 2.5 D displacement field decomposed from the InSAR observations. The determined uniform slip fault model shows that the dip angle of the seimogenic fault is approximately 40°, with a strike of 120° except for a narrower fault width than that predicted by the empirical scaling law. We suggest that geometric complexities near the Kopeh Dagh fault system obstruct the rupture propagation, resulting in high slip occurred within a small area and much higher stress drop than global estimates. The InSAR-determined moment is 1.71 × 1018 Nm with a shear modulus of 3.32 × 1010 N/m2, equivalent to Mw 6.12, which is consistent with seismological results. The finite fault model (the west-dipping fault plane) reveals that the peak slip of 0.90 m occurred at a depth of 6.3 km, with substantial slip at a depth of 4-10 km and a near-uniform slip of 0.1 m at a depth of 0-2.5 km. We suggest that the Sangsefid earthquake occurred on an unknown blind reverse fault dipping southwest, which can also be recognised through observing the long-term surface effects due to the existence of the blind

  15. Deformed Fluvial Terraces of Little Rock Creek Capture Off-Fault Strain Adjacent to the Mojave Section of the San Andreas Fault

    Science.gov (United States)

    Moulin, A.; Scharer, K. M.; Cowgill, E.

    2017-12-01

    Examining discrepancies between geodetic and geomorphic slip-rates along major strike-slip faults is essential for understanding both fault behavior and seismic hazard. Recent work on major strike-slip faults has highlighted off-fault deformation and its potential impact on fault slip rates. However, the extent of off-fault deformation along the San Andreas Fault (SAF) remains largely uncharacterized. Along the Mojave section of the SAF, Little Rock Creek drains from south to north across the fault and has cut into alluvial terraces abandoned between 15 and 30 ka1. The surfaces offer a rare opportunity to both characterize how right-lateral slip has accumulated along the SAF over hundreds of seismic cycles, and investigate potential off-fault deformation along secondary structures, where strain accumulates at slower rates. Here we use both field observations and DEM analysis of B4 lidar data to map alluvial and tectonic features, including 9 terrace treads that stand up to 80 m above the modern channel. We interpret the abandonment and preservation of the fluvial terraces to result from episodic capture of Little Rock Creek through gaps in a shutter ridge north of the fault, followed by progressive right deflection of the river course during dextral slip along the SAF. Piercing lines defined by fluvial terrace risers suggest that the amount of right slip since riser formation ranges from 400m for the 15-ka-riser to 1200m for the 30-ka-riser. Where they are best-preserved NE of the SAF, terraces are also cut by NE-facing scarps that trend parallel to the SAF in a zone extending up to 2km from the main fault. Exposures indicate these are fault scarps, with both reverse and normal stratigraphic separation. Geomorphic mapping reveals deflections of both channel and terrace risers (up to 20m) along some of those faults suggesting they could have accommodated a component of right-lateral slip. We estimated the maximum total amount of strike-slip motion recorded by the

  16. 14 CFR 35.38 - Lightning strike.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning strike. 35.38 Section 35.38... STANDARDS: PROPELLERS Tests and Inspections § 35.38 Lightning strike. The applicant must demonstrate, by... lightning strike without causing a major or hazardous propeller effect. The limit to which the propeller has...

  17. How informative are slip models for aftershock forecasting?

    Science.gov (United States)

    Bach, Christoph; Hainzl, Sebastian

    2013-04-01

    Coulomb stress changes (ΔCFS) have been recognized as a major trigger mechanism for earthquakes, in particular aftershock distributions and the spatial patterns of ΔCFS are often found to be correlated. However, the Coulomb stress calculations are based on slip inversions and the receiver fault mechanisms which both contain large uncertainties. In particular, slip inversions are usually non-unique and often differ strongly for the same earthquakes. Here we want to address the information content of those inversions with respect to aftershock forecasting. Therefore we compare the slip models to randomized fractal slip models which are only constrained by fault information and moment magnitude. The uncertainty of the aftershock mechanisms is considered by using many receiver fault orientations, and by calculating ΔCFS at several depth layers. The stress change is then converted into an aftershock probability map utilizing a clock advance model. To estimate the information content of the slip models, we use an Epidemic Type Aftershock Sequence (ETAS) model approach introduced by Bach and Hainzl (2012), where the spatial probability density of direct aftershocks is related to the ΔCFS calculations. Besides the directly triggered aftershocks, this approach also takes secondary aftershock triggering into account. We quantify our results by calculating the information gain of the randomized slip models relative to the corresponding published slip model. As case studies, we investigate the aftershock sequences of several well-known main shocks such as 1992 Landers, 1999 Hector Mine, 2004 Parkfield, 2002 Denali. First results show a huge difference in the information content of slip models. For some of the cases up to 90% of the random slip models are found to perform better than the originally published model, for some other cases only few random models are found performing better than the published slip model.

  18. Strikes in Serbia since 2000 to 2005

    OpenAIRE

    Novaković Nada

    2005-01-01

    In this article author deals with main characteristics of strikes in Serbia within the period 2000–2005. Analysis starts with thesis that strike is open class conflict within class divided society. Therefore strike is radical form of trade union struggle for workers rights. Main questions in the analysis were: on social structure as a background of strikes, on organizations and trade unions included in it, on effects of strikes in Serbia in the given period. Main thesis of the article is that...

  19. Options with Extreme Strikes

    Directory of Open Access Journals (Sweden)

    Lingjiong Zhu

    2015-07-01

    Full Text Available In this short paper, we study the asymptotics for the price of call options for very large strikes and put options for very small strikes. The stock price is assumed to follow the Black–Scholes models. We analyze European, Asian, American, Parisian and perpetual options and conclude that the tail asymptotics for these option types fall into four scenarios.

  20. Axisymmetric Tornado Simulations with a Semi-Slip Boundary

    Directory of Open Access Journals (Sweden)

    Brian H. Fiedler

    2017-12-01

    Full Text Available The structure of natural tornadoes and simulated analogs are sensitive to the lower boundary condition for friction. Three-dimensional numerical simulations of storms require a choice for turbulence parameterizations and resolution of wind near the lower boundary. This article explores some of the consequences of choices of a surface drag coefficient on the structure of a mature simulated tornado, using a conventional axisymmetric model. The surface drag parameterization is explored over the range of the semi-slip condition, including the extremes of no-slip and free-slip. A moderate semi-slip condition allows for an extreme pressure deficit, but without the unrealistic vortex breakdown of the no-slip condition.

  1. Dynamic slip of polydisperse linear polymers using partitioned plate

    Science.gov (United States)

    Ebrahimi, Marzieh; Konaganti, Vinod Kumar; Hatzikiriakos, Savvas G.

    2018-03-01

    The slip velocity of an industrial grade high molecular weight high-density polyethylene (HDPE) is studied in steady and dynamic shear experiments using a stress/strain controlled rotational rheometer equipped with a parallel partitioned plate geometry. Moreover, fluoroalkyl silane-based coating is used to understand the effect of surface energy on slip in steady and dynamic conditions. The multimode integral Kaye-Bernstein-Kearsley-Zapas constitutive model is applied to predict the transient shear response of the HDPE melt obtained from rotational rheometer. It is found that a dynamic slip model with a slip relaxation time is needed to adequately predict the experimental data at large shear deformations. Comparison of the results before and after coating shows that the slip velocity is largely affected by surface energy. Decreasing surface energy by coating increases slip velocity and decreases the slip relaxation time.

  2. Earthquake source properties from instrumented laboratory stick-slip

    Science.gov (United States)

    Kilgore, Brian D.; McGarr, Arthur F.; Beeler, Nicholas M.; Lockner, David A.; Thomas, Marion Y.; Mitchell, Thomas M.; Bhat, Harsha S.

    2017-01-01

    Stick-slip experiments were performed to determine the influence of the testing apparatus on source properties, develop methods to relate stick-slip to natural earthquakes and examine the hypothesis of McGarr [2012] that the product of stiffness, k, and slip duration, Δt, is scale-independent and the same order as for earthquakes. The experiments use the double-direct shear geometry, Sierra White granite at 2 MPa normal stress and a remote slip rate of 0.2 µm/sec. To determine apparatus effects, disc springs were added to the loading column to vary k. Duration, slip, slip rate, and stress drop decrease with increasing k, consistent with a spring-block slider model. However, neither for the data nor model is kΔt constant; this results from varying stiffness at fixed scale.In contrast, additional analysis of laboratory stick-slip studies from a range of standard testing apparatuses is consistent with McGarr's hypothesis. kΔt is scale-independent, similar to that of earthquakes, equivalent to the ratio of static stress drop to average slip velocity, and similar to the ratio of shear modulus to wavespeed of rock. These properties result from conducting experiments over a range of sample sizes, using rock samples with the same elastic properties as the Earth, and scale-independent design practices.

  3. Pleistocene slip rates on the Boconó fault along the North Andean Block plate boundary, Venezuela

    Science.gov (United States)

    Pousse-Beltran, Lea; Vassallo, Riccardo; Audemard, Franck; Jouanne, François; Carcaillet, Julien; Pathier, Erwan; Volat, Matthieu

    2017-07-01

    The Boconó fault is a strike-slip fault lying between the North Andean Block and the South American plate which has triggered at least five Mw > 7 historical earthquakes in Venezuela. The North Andean Block is currently moving toward NNE with respect to a stable South American plate. This relative displacement at 12 mm yr-1 in Venezuela (within the Maracaibo Block) was measured by geodesy, but until now the distribution and rates of Quaternary deformation have remained partially unclear. We used two alluvial fans offset by the Boconó fault (Yaracuy Valley) to quantify slip rates, by combining 10Be cosmogenic dating with measurements of tectonic displacements on high-resolution satellite images (Pleiades). Based upon a fan dated at >79 ka and offset by 1350-1580 m and a second fan dated at 120-273 ka and offset by 1236-1500 m, we obtained two Pleistocene rates of 5.0-11.2 and <20.0 mm yr-1, consistent with the regional geodesy. This indicates that the Boconó fault in the Yaracuy Valley accommodates 40 to 100% of the deformation between the South American plate and the Maracaibo Block. As no aseismic deformation was shown by interferometric synthetic aperture radar analysis, we assume that the fault is locked since the 1812 event. This implies that there is a slip deficit in the Yaracuy Valley since the last earthquake ranging from 1 to 4 m, corresponding to a Mw 7-7.6 earthquake. This magnitude is comparable to the 1812 earthquake and to other historical events along the Boconó fault.

  4. Estimation of slip scenarios of mega-thrust earthquakes and strong motion simulations for Central Andes, Peru

    Science.gov (United States)

    Pulido, N.; Tavera, H.; Aguilar, Z.; Chlieh, M.; Calderon, D.; Sekiguchi, T.; Nakai, S.; Yamazaki, F.

    2012-12-01

    We have developed a methodology for the estimation of slip scenarios for megathrust earthquakes based on a model of interseismic coupling (ISC) distribution in subduction margins obtained from geodetic data, as well as information of recurrence of historical earthquakes. This geodetic slip model (GSM) delineates the long wavelength asperities within the megathrust. For the simulation of strong ground motion it becomes necessary to introduce short wavelength heterogeneities to the source slip to be able to efficiently simulate high frequency ground motions. To achieve this purpose we elaborate "broadband" source models constructed by combining the GSM with several short wavelength slip distributions obtained from a Von Karman PSD function with random phases. Our application of the method to Central Andes in Peru, show that this region has presently the potential of generating an earthquake with moment magnitude of 8.9, with a peak slip of 17 m and a source area of approximately 500 km along strike and 165 km along dip. For the strong motion simulations we constructed 12 broadband slip models, and consider 9 possible hypocenter locations for each model. We performed strong motion simulations for the whole central Andes region (Peru), spanning an area from the Nazca ridge (16^o S) to the Mendana fracture (9^o S). For this purpose we use the hybrid strong motion simulation method of Pulido et al. (2004), improved to handle a general slip distribution. Our simulated PGA and PGV distributions indicate that a region of at least 500 km along the coast of central Andes is subjected to a MMI intensity of approximately 8, for the slip model that yielded the largest ground motions among the 12 slip models considered, averaged for all assumed hypocenter locations. This result is in agreement with the macroseismic intensity distribution estimated for the great 1746 earthquake (M~9) in central Andes (Dorbath et al. 1990). Our results indicate that the simulated PGA and PGV for

  5. Women, transition and strikes in Serbia

    Directory of Open Access Journals (Sweden)

    Novaković Nada G.

    2014-01-01

    Full Text Available The author, in a sociological way, describes and analyzes the concepts of transition, privatization and strikes in Serbia, particularly the place of women in it. It examines the most important economic and social causes and consequences of these phenomena. The main hypothesis is: women's strikes in the Serbian transition are less efficient than strikes and public protests of women in the developed world and the second Yugoslavia. A strike is a class conflict, in which the workers are fighting for their social and economic rights, threatened by the capitalist class. Elites in government and state authorities protect the interests of big capital at the detriment of the interests of the majority of workers. Exploring women's strikes in transition reveals the nature of the social and political system. Their strikes in enterprises, the blocking of public spaces and public protests are systemic, ie. class determined. As the transition was very fast, the resistance of the strikers was inefficient, and the protests of women became an expression of desperation against the loss of jobs and basic resources for lifehood. In short, this research is about the main causes, the organizational forms and the consequences of strikes in which the majority were women. For this purpose, the author chose to describe an array of strikes in the industries and the companies where women are most employed. The choice of strikes in the economic sector is not accidental, but a consequence of the fact that the women there were the most vulnerable. Women in public institutions and companies had much higher financial and social position. They are less likely to strike and publicly protested. After 2000, these strikes were more successful than worker's strikes in textile, food processing, manufacturing and trade. Relationship between the government and the public towards them was tainted by self-interest and selective. The main criterion for the selection of companies and

  6. RETRAN dynamic slip model

    International Nuclear Information System (INIS)

    McFadden, J.H.; Paulsen, M.P.; Gose, G.C.

    1981-01-01

    A time dependent equation for the slip velocity in a two-phase flow condition has been incorporated into a developmental version of the RETRAN computer code. This model addition has been undertaken to remove a limitation in RETRAN-01 associated with the homogeneous equilibrium mixture model. In this paper, the development of the slip model is summarized and the corresponding constitutive equations are discussed. Comparisons of RETRAN analyses with steady-state void fraction data and data from the Semiscale S-02-6 small break test are also presented

  7. RETRAN dynamic slip model

    International Nuclear Information System (INIS)

    McFadden, J.H.; Paulsen, M.P.; Gose, G.C.

    1981-01-01

    Thermal-hydraulic codes in general use for system calculations are based on extensive analyses of loss-of-coolant accidents following the postulated rupture of a large coolant pipe. In this study, time-dependent equation for the slip velocity in a two-phase flow condition has been incorporated into the RETRAN-02 computer code. This model addition was undertaken to remove a limitation in RETRAN-01 associated with the homogeneous equilibrium mixture model. The dynamic slip equation was derived from a set of two-fluid conservation equations. 18 refs

  8. [Physicians' strikes--ethical considerations].

    Science.gov (United States)

    Glick, Shimon; Schwarzfuchs, Dan

    2012-01-01

    Strikes in general represent a solution based on a form of coercion. Historically, the striker caused direct damage to his employer, who was responsible for the perceived unfair treatment of the employee. In the case of strikes in the public sector, the employer is generally not harmed, but innocent citizens suffer in order to pressure the government agencies, a questionable practice from an ethical viewpoint. Physicians' strikes have more serious ethical problems. They cause suffering and death to innocent citizens. They violate the ethical codes to which physicians have committed themselves as professionals, and they seriously impair the trust of the public in physicians. Better and more ethical ways to provide fair compensation for physicians must be employed, perhaps like those used for judges and members of the IDF.

  9. Preemptive strikes: Fear, hope, and defensive aggression.

    Science.gov (United States)

    Halevy, Nir

    2017-02-01

    Preemptive strikes are costly and harmful. Existing models of defensive aggression focus narrowly on the role fear plays in motivating preemptive strikes. Theoretically integrating the literatures on conflict, decision making, and emotion, the current research investigated how specific emotions associated with certainty or uncertainty, including fear, anger, disgust, hope, and happiness, influence preemptive strikes. Study 1 demonstrated that hope negatively predicts defensive exits from relationships in choice dilemmas. Studies 2 and 3 experimentally manipulated risk of being attacked in an incentivized, interactive decision making task-the Preemptive Strike Game. Risk of being attacked fueled preemptive strikes; reduced feelings of hope partially mediated this effect in Study 3. Studies 4 and 5 investigated preemptive strikes under uncertainty (rather than risk). In Study 4, reasoning about the factors that make one trustful of others curbed preemptive strikes; cogitating about the factors that underlie discrete emotions, however, did not influence defensive aggression. Study 5 demonstrated that the valence and uncertainty appraisals of incidental emotions interact in shaping preemptive strikes. Specifically, recalling an autobiographical emotional experience that produced hope significantly decreased attack rates relative to fear, happiness, and a control condition. Fear, anger, disgust, and happiness were either unrelated to preemptive strikes or showed inconsistent relationships with preemptive strikes across the 5 studies. These findings shed light on how emotions shape defensive aggression, advance knowledge on strategic choice under risk and uncertainty, and demonstrate hope's positive effects on social interactions and relationships. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  10. Heterogeneous rupture in the great Cascadia earthquake of 1700 inferred from coastal subsidence estimates

    Science.gov (United States)

    Wang, Pei-Ling; Engelhart, Simon E.; Wang, Kelin; Hawkes, Andrea D.; Horton, Benjamin P.; Nelson, Alan R.; Witter, Robert C.

    2013-01-01

    Past earthquake rupture models used to explain paleoseismic estimates of coastal subsidence during the great A.D. 1700 Cascadia earthquake have assumed a uniform slip distribution along the megathrust. Here we infer heterogeneous slip for the Cascadia margin in A.D. 1700 that is analogous to slip distributions during instrumentally recorded great subduction earthquakes worldwide. The assumption of uniform distribution in previous rupture models was due partly to the large uncertainties of then available paleoseismic data used to constrain the models. In this work, we use more precise estimates of subsidence in 1700 from detailed tidal microfossil studies. We develop a 3-D elastic dislocation model that allows the slip to vary both along strike and in the dip direction. Despite uncertainties in the updip and downdip slip extensions, the more precise subsidence estimates are best explained by a model with along-strike slip heterogeneity, with multiple patches of high-moment release separated by areas of low-moment release. For example, in A.D. 1700, there was very little slip near Alsea Bay, Oregon (~44.4°N), an area that coincides with a segment boundary previously suggested on the basis of gravity anomalies. A probable subducting seamount in this area may be responsible for impeding rupture during great earthquakes. Our results highlight the need for more precise, high-quality estimates of subsidence or uplift during prehistoric earthquakes from the coasts of southern British Columbia, northern Washington (north of 47°N), southernmost Oregon, and northern California (south of 43°N), where slip distributions of prehistoric earthquakes are poorly constrained.

  11. Slip-mediated dewetting of polymer microdroplets

    Science.gov (United States)

    McGraw, Joshua D.; Chan, Tak Shing; Maurer, Simon; Salez, Thomas; Benzaquen, Michael; Raphaël, Elie; Brinkmann, Martin; Jacobs, Karin

    2016-01-01

    Classical hydrodynamic models predict that infinite work is required to move a three-phase contact line, defined here as the line where a liquid/vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap-shaped polystyrene microdroplets, with nonequilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using in situ atomic force microscopy. We find that slip has a strong influence on the droplet evolutions, both on the transient nonspherical shapes and contact line dynamics. The observations are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition. PMID:26787903

  12. Multiparameter Monitoring and Prevention of Fault-Slip Rock Burst

    Directory of Open Access Journals (Sweden)

    Shan-chao Hu

    2017-01-01

    Full Text Available Fault-slip rock burst is one type of the tectonic rock burst during mining. A detailed understanding of the precursory information of fault-slip rock burst and implementation of monitoring and early warning systems, as well as pressure relief measures, are essential to safety production in deep mines. This paper first establishes a mechanical model of stick-slip instability in fault-slip rock bursts and then reveals the failure characteristics of the instability. Then, change rule of mining-induced stress and microseismic signals before the occurrence of fault-slip rock burst are proposed, and multiparameter integrated early warning methods including mining-induced stress and energy are established. Finally, pressure relief methods targeting large-diameter boreholes and coal seam infusion are presented in accordance with the occurrence mechanism of fault-slip rock burst. The research results have been successfully applied in working faces 2310 of the Suncun Coal Mine, and the safety of the mine has been enhanced. These research results improve the theory of fault-slip rock burst mechanisms and provide the basis for prediction and forecasting, as well as pressure relief, of fault-slip rock bursts.

  13. Slip reactivation model for the 2011 Mw9 Tohoku earthquake: Dynamic rupture, sea floor displacements and tsunami simulations.

    Science.gov (United States)

    Galvez, P.; Dalguer, L. A.; Rahnema, K.; Bader, M.

    2014-12-01

    The 2011 Mw9 Tohoku earthquake has been recorded with a vast GPS and seismic network given unprecedented chance to seismologists to unveil complex rupture processes in a mega-thrust event. In fact more than one thousand near field strong-motion stations across Japan (K-Net and Kik-Net) revealed complex ground motion patterns attributed to the source effects, allowing to capture detailed information of the rupture process. The seismic stations surrounding the Miyagi regions (MYGH013) show two clear distinct waveforms separated by 40 seconds. This observation is consistent with the kinematic source model obtained from the inversion of strong motion data performed by Lee's et al (2011). In this model two rupture fronts separated by 40 seconds emanate close to the hypocenter and propagate towards the trench. This feature is clearly observed by stacking the slip-rate snapshots on fault points aligned in the EW direction passing through the hypocenter (Gabriel et al, 2012), suggesting slip reactivation during the main event. A repeating slip on large earthquakes may occur due to frictional melting and thermal fluid pressurization effects. Kanamori & Heaton (2002) argued that during faulting of large earthquakes the temperature rises high enough creating melting and further reduction of friction coefficient. We created a 3D dynamic rupture model to reproduce this slip reactivation pattern using SPECFEM3D (Galvez et al, 2014) based on a slip-weakening friction with sudden two sequential stress drops . Our model starts like a M7-8 earthquake breaking dimly the trench, then after 40 seconds a second rupture emerges close to the trench producing additional slip capable to fully break the trench and transforming the earthquake into a megathrust event. The resulting sea floor displacements are in agreement with 1Hz GPS displacements (GEONET). The seismograms agree roughly with seismic records along the coast of Japan.The simulated sea floor displacement reaches 8-10 meters of

  14. Frictional melting and stick-slip behavior in volcanic conduits

    Science.gov (United States)

    Kendrick, Jackie Evan; Lavallee, Yan; Hirose, Takehiro; di Toro, Giulio; Hornby, Adrian Jakob; Hess, Kai-Uwe; Dingwell, Donald Bruce

    2013-04-01

    Dome-building eruptions have catastrophic potential, with dome collapse leading to devastating pyroclastic flows with almost no precursory warning. During dome growth, the driving forces of the buoyant magma may be superseded by controls along conduit margins; where brittle fracture and sliding can lead to formation of lubricating cataclasite and gouge. Under extreme friction, pseudotachylyte may form at the conduit margin. Understanding the conduit margin processes is vital to understanding the continuation of an eruption and we postulate that pseudotachylyte generation could be the underlying cause of stick-slip motion and associated seismic "drumbeats", which are so commonly observed at dome-building volcanoes. This view is supported by field evidence in the form of pseudotachylytes identified in lava dome products at Soufrière Hills (Montserrat) and Mount St. Helens (USA). Both eruptions were characterised by repetitive, periodic seismicity and lava spine extrusion of highly viscous magma. High velocity rotary shear (HVR) experiments demonstrate the propensity for melting of the andesitic and dacitic material (from Soufrière Hills and Mount St. Helens respectively) at upper conduit stress conditions (HVR experiments which mimic rapid velocity fluctuations in stick-slip behavior demonstrate velocity-weakening behavior of melt, with a tendency for unstable slip. During ascent, magma may slip and undergo melting along the conduit margin. In the process the shear resistance of the slip zone is increased, acting as a viscous brake halting slip (the "stick" of stick-slip motion). Sufficient buoyancy-driven pressures from ascending magma below eventually overcome resistance to produce a rapid slip event (the "slip") along the melt-bearing slip zone, which is temporarily lubricated due to velocity-weakening. New magma below experiences the same slip event more slowly (as the magma decompresses) to produce a viscous brake and the process is repeated. This allows a

  15. No slip gravity

    Science.gov (United States)

    Linder, Eric V.

    2018-03-01

    A subclass of the Horndeski modified gravity theory we call No Slip Gravity has particularly interesting properties: 1) a speed of gravitational wave propagation equal to the speed of light, 2) equality between the effective gravitational coupling strengths to matter and light, Gmatter and Glight, hence no slip between the metric potentials, yet difference from Newton's constant, and 3) suppressed growth to give better agreement with galaxy clustering observations. We explore the characteristics and implications of this theory, and project observational constraints. We also give a simple expression for the ratio of the gravitational wave standard siren distance to the photon standard candle distance, in this theory and others, and enable a direct comparison of modified gravity in structure growth and in gravitational waves, an important crosscheck.

  16. Slip patterns and preferred dislocation boundary planes

    DEFF Research Database (Denmark)

    Winther, G.

    2003-01-01

    The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single and polycryst......The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single...... and polycrystals of fcc metals in three deformation modes (rolling, tension and torsion). In the macroscopic system, boundaries lie close to the macroscopically most stressed planes. In the crystallographic system, the boundary plane depends on the grain/crystal orientation. The boundary planes in both co......-ordinate systems are rationalised based on the slip. The more the slip is concentrated on a slip plane, the closer the boundaries lie to this. The macroscopic preference arises from the macroscopic directionality of the slip. The established relations are applied to (a) prediction of boundary planes from slip...

  17. Slip-accumulation patterns and earthquake recurrences along the Talas-Fergana Fault - Contributions of high-resolution geomorphic offsets.

    Science.gov (United States)

    Rizza, M.; Dubois, C.; Fleury, J.; Abdrakhmatov, K.; Pousse, L.; Baikulov, S.; Vezinet, A.

    2017-12-01

    In the western Tien-Shan Range, the largest intracontinental strike-slip fault is the Karatau-Talas Fergana Fault system. This dextral fault system is subdivided into two main segments: the Karatau fault to the north and the Talas-Fergana fault (TFF) to the south. Kinematics and rates of deformation for the TFF during the Quaternary period are still debated and are poorly constrained. Only a few paleoseismological investigations are availabe along the TFF (Burtman et al., 1996; Korjenkov et al., 2010) and no systematic quantifications of the dextral displacements along the TFF has been undertaken. As such, the appraisal of the TFF behavior demands new tectonic information. In this study, we present the first detailed analysis of the morphology and the segmentation of the TFF and an offset inventory of morphological markers along the TFF. To discuss temporal and spatial recurrence patterns of slip accumulated over multiple seismic events, our study focused on a 60 km-long section of the TFF (Chatkal segment). Using tri-stereo Pleiades satellite images, high-resolution DEMs (1*1 m pixel size) have been generated in order to (i) analyze the fine-scale fault geometry and (ii) thoroughly measure geomorphic offsets. Photogrammetry data obtained from our drone survey on high interest sites, provide higher-resolution DEMs of 0.5 * 0.5 m pixel size.Our remote sensing mapping allows an unprecedented subdivision - into five distinct segments - of the study area. About 215 geomorphic markers have been measured and offsets range from 4.5m to 180 m. More than 80% of these offsets are smaller than 60 m, suggesting landscape reset during glacial maximum. Calculations of Cumulative Offset Probability Density (COPD) for the whole 60 km-long section as well as for each segments support distinct behavior from a segment to another and thus variability in slip-accumulation patterns. Our data argue for uniform slip model behavior along this section of the TFF. Moreover, we excavated a

  18. Slip transmission in bcc FeCr polycrystal

    Energy Technology Data Exchange (ETDEWEB)

    Patriarca, Luca, E-mail: luca.patriarca@polimi.it [Politecnico di Milano, Department of Mechanical Engineering, Via La Masa 34, I-20156 Milano (Italy); Abuzaid, Wael; Sehitoglu, Huseyin [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206W. Green St., Urbana, IL 61801 (United States); Maier, Hans J. [Institut für Werkstoffkunde, Leibniz Universität Hannover, An der Universität 2, D-30823 Garbsen (Germany)

    2013-12-20

    Grain boundaries induce heterogeneities in the deformation response of polycrystals. Studying these local variations in response, measured through high resolution strain measurement techniques, is important and can improve our understanding of fatigue damage initiation in the vicinity of grain boundaries and material hardening. In this work, strain fields across grain boundaries were measured using advanced digital image correlation techniques. In conjunction with strain measurements, grain orientations from electron back-scattered diffraction were used to establish the dislocation reactions at each boundary, providing the corresponding residual Burgers vectors due to slip transmission across the interfaces. A close correlation was found between the magnitude of the residual Burgers vector and the local strain change across the boundary. When the residual Burgers vector magnitude (with respect to the lattice spacing) exceeds 1.0, the high strains on one side of the boundary are paired with low strains across the boundary, indicating the difficulties for slip dislocations to penetrate the grain interfaces. When the residual Burgers vector approaches zero, the strain fields vary smoothly across the boundary due to limited resistance to slip transmission. The results suggest that the residual Burgers vector magnitude, which relates to the GB (Grain Boundary) resistance to slip transmission, enables a quantitative analysis of the accumulation of strain at the microstructural level and the development of strain heterogeneities across grain boundaries. The results are presented for FeCr bcc alloy which exhibits single slip per grain making the measurements and dislocation reactions rather straightforward. The work points to the need to incorporate details of slip dislocation–grain boundary interaction (slip transmission) in modeling research.

  19. Nonequilibrium Chromosome Looping via Molecular Slip Links

    Science.gov (United States)

    Brackley, C. A.; Johnson, J.; Michieletto, D.; Morozov, A. N.; Nicodemi, M.; Cook, P. R.; Marenduzzo, D.

    2017-09-01

    We propose a model for the formation of chromatin loops based on the diffusive sliding of molecular slip links. These mimic the behavior of molecules like cohesin, which, along with the CTCF protein, stabilize loops which contribute to organizing the genome. By combining 3D Brownian dynamics simulations and 1D exactly solvable nonequilibrium models, we show that diffusive sliding is sufficient to account for the strong bias in favor of convergent CTCF-mediated chromosome loops observed experimentally. We also find that the diffusive motion of multiple slip links along chromatin is rectified by an intriguing ratchet effect that arises if slip links bind to the chromatin at a preferred "loading site." This emergent collective behavior favors the extrusion of loops which are much larger than the ones formed by single slip links.

  20. Preliminary soil-slip susceptibility maps, southwestern California

    Science.gov (United States)

    Morton, Douglas M.; Alvarez, Rachel M.; Campbell, Russell H.; Digital preparation by Bovard, Kelly R.; Brown, D.T.; Corriea, K.M.; Lesser, J.N.

    2003-01-01

    This group of maps shows relative susceptibility of hill slopes to the initiation sites of rainfall-triggered soil slip-debris flows in southwestern California. As such, the maps offer a partial answer to one part of the three parts necessary to predict the soil-slip/debris-flow process. A complete prediction of the process would include assessments of “where”, “when”, and “how big”. These maps empirically show part of the “where” of prediction (i.e., relative susceptibility to sites of initiation of the soil slips) but do not attempt to show the extent of run out of the resultant debris flows. Some information pertinent to “when” the process might begin is developed. “When” is determined mostly by dynamic factors such as rainfall rate and duration, for which local variations are not amenable to long-term prediction. “When” information is not provided on the maps but is described later in this narrative. The prediction of “how big” is addressed indirectly by restricting the maps to a single type of landslide process—soil slip-debris flows. The susceptibility maps were created through an iterative process from two kinds of information. First, locations of sites of past soil slips were obtained from inventory maps of past events. Aerial photographs, taken during six rainy seasons that produced abundant soil slips, were used as the basis for soil slip-debris flow inventory. Second, digital elevation models (DEM) of the areas that were inventoried were used to analyze the spatial characteristics of soil slip locations. These data were supplemented by observations made on the ground. Certain physical attributes of the locations of the soil-slip debris flows were found to be important and others were not. The most important attribute was the mapped bedrock formation at the site of initiation of the soil slip. However, because the soil slips occur in surficial materials overlying the bedrocks units, the bedrock formation can only serve as

  1. Using Low-Frequency Earthquakes to Investigate Slow Slip Processes and Plate Interface Structure Beneath the Olympic Peninsula, WA

    Science.gov (United States)

    Chestler, Shelley

    . Using observed and calculated values for AP, AT and ST we evaluate two end- member models for LFE slip within an LFE family patch (models 2 and 3 from chapter 1). In the ductile matrix model (model 3), LFEs produce 100% of the observed ETS slip (SETS) in distinct sub-patches (i.e., AT AP). In the connected patch model (model 2), AT =AP, but STfamilies. Spatial gaps (˜10-20 km) between LFE family clusters and smaller gaps within LFE family clusters serve as evidence that LFE slip is heterogeneous on multiple spatial scales. We find that LFE slip only accounts for ˜0.2% of the slip within the slow slip zone. There are downdip trends in the characteristic (mean) moment and in the number of LFEs during both ETS events (only) and the entire ETS cycle (Mc,ETS and NT,ETS and Mc,all and NT,all respectively). During ETS, Mc decreases with downdip distance but NT does not change. Over the entire ETS cycle, Mc decreases with downdip distance, but NT increases. These observations indicate that downdip LFE slip occurs through a larger number (800-1200) of small LFEs, while updip LFE slip occurs primarily during ETS events through a smaller number (200-600) of larger LFEs. This could indicate that the plate interface is stronger and has a higher stress threshold updip. In the third chapter, we use high-precision, relative low-frequency earthquake (LFE) locations for LFEs beneath the Olympic Peninsula, WA to constrain the depth, geometry, and thickness of the plate interface. LFE depths correspond most closely with the McCrory et al. (2012) plate model, but vary from that smooth model along strike. The latter observation indicates that the actual plate interface is notably rougher and more complex than smooth plate models. Our LFEs lie directly above low-velocity zone (LVZ) and approximately 5 km above intraslab earthquakes. This supports the proposal of Bostock (2013), that the LVZ comprises the upper oceanic crust and that fluids are responsible for the velocity contrast across

  2. Relation between boundary slip mechanisms and waterlike fluid behavior

    Science.gov (United States)

    Ternes, Patricia; Salcedo, Evy; Barbosa, Marcia C.

    2018-03-01

    The slip of a fluid layer in contact with a solid confining surface is investigated for different temperatures and densities using molecular dynamic simulations. We show that for an anomalous waterlike fluid the slip goes as follows: for low levels of shear, defect slip appears and is related to the particle exchange between the fluid layers; at high levels of shear, global slip occurs and is related to the homogeneous distribution of the fluid in the confining surfaces. The oscillations in the transition velocity from defect to global slip are shown to be associated with changes in the layering distribution in the anomalous fluid.

  3. Slip parameters on major thrusts at a convergent plate boundary: regional heterogeneity of potential slip distance at the shallow portion of the subducting plate

    Science.gov (United States)

    Mukoyoshi, Hideki; Kaneki, Shunya; Hirono, Tetsuro

    2018-03-01

    Understanding variations of slip distance along major thrust systems at convergent margins is an important issue for evaluation of near-trench slip and the potential generation of large tsunamis. We derived quantitative estimates of slip along ancient subduction fault systems by using the maturity of carbonaceous material (CM) of discrete slip zones as a proxy for temperature. We first obtained the Raman spectra of CM in ultracataclasite and pseudotachylyte layers in discrete slip zones at depths below the seafloor of 1-4 km and 2.5-5.5 km, respectively. By comparing the area-under-the-peak ratios of graphitic and disordered bands in those Raman spectra with spectra of experimentally heated CM from surrounding rocks, we determined that the ultracataclasite and pseudotachylyte layers had been heated to temperatures of up to 700 and 1300 °C, respectively. Numerical simulation of the thermal history of CM extracted from rocks near the two slip zones, taking into consideration these temperature constraints, indicated that slip distances in the ultracataclasite and pseudotachylyte layers were more than 3 and 7 m, respectively. Thus, potential distance of coseismic slip along the subduction-zone fault system could have regional variations even at shallow depth (≤ 5.5 km). The slip distances we determined probably represent minimum slips for subduction-zone thrusts and thus provide an important contribution to earthquake preparedness plans in coastal areas facing the Nankai and Sagami Troughs.

  4. Spatiotemporal patterns of fault slip rates across the Central Sierra Nevada frontal fault zone

    Science.gov (United States)

    Rood, Dylan H.; Burbank, Douglas W.; Finkel, Robert C.

    2011-01-01

    Patterns in fault slip rates through time and space are examined across the transition from the Sierra Nevada to the Eastern California Shear Zone-Walker Lane belt. At each of four sites along the eastern Sierra Nevada frontal fault zone between 38 and 39° N latitude, geomorphic markers, such as glacial moraines and outwash terraces, are displaced by a suite of range-front normal faults. Using geomorphic mapping, surveying, and 10Be surface exposure dating, mean fault slip rates are defined, and by utilizing markers of different ages (generally, ~ 20 ka and ~ 150 ka), rates through time and interactions among multiple faults are examined over 10 4-10 5 year timescales. At each site for which data are available for the last ~ 150 ky, mean slip rates across the Sierra Nevada frontal fault zone have probably not varied by more than a factor of two over time spans equal to half of the total time interval (~ 20 ky and ~ 150 ky timescales): 0.3 ± 0.1 mm year - 1 (mode and 95% CI) at both Buckeye Creek in the Bridgeport basin and Sonora Junction; and 0.4 + 0.3/-0.1 mm year - 1 along the West Fork of the Carson River at Woodfords. Data permit rates that are relatively constant over the time scales examined. In contrast, slip rates are highly variable in space over the last ~ 20 ky. Slip rates decrease by a factor of 3-5 northward over a distance of ~ 20 km between the northern Mono Basin (1.3 + 0.6/-0.3 mm year - 1 at Lundy Canyon site) to the Bridgeport Basin (0.3 ± 0.1 mm year - 1 ). The 3-fold decrease in the slip rate on the Sierra Nevada frontal fault zone northward from Mono Basin is indicative of a change in the character of faulting north of the Mina Deflection as extension is transferred eastward onto normal faults between the Sierra Nevada and Walker Lane belt. A compilation of regional deformation rates reveals that the spatial pattern of extension rates changes along strike of the Eastern California Shear Zone-Walker Lane belt. South of the Mina Deflection

  5. Lateral Offset Quality Rating along Low Slip Rate Faults: Application to the Alhama de Murcia Fault (SE Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    Marta Ferrater

    2015-11-01

    Full Text Available Seismic hazard assessment of strike-slip faults is based partly on the identification and mapping of landforms laterally offset due to fault activity. The characterization of these features affected by slow-moving faults is challenging relative to studies emphasizing rapidly slipping faults. We propose a methodology for scoring fault offsets based on subjective and objective qualities. We apply this methodology to the Alhama de Murcia fault (SE Iberian Peninsula where we identify 138 offset features that we mapped on a high-resolution (0.5 × 0.5 m pixel size Digital Elevation Model (DEM. The amount of offset, the uncertainty of the measurement, the subjective and objective qualities, and the parameters that affect objective quality are independent variables, suggesting that our methodological scoring approach is good. Based on the offset measurements and qualifications we calculate the Cumulative Offset Probability Density (COPD for the entire fault and for each fault segment. The COPD for the segments differ from each other. Tentative interpretation of the COPDs implies that the slip rate varies from one segment to the other (we assume that channels with the same amount of offset were incised synchronously. We compare the COPD with climate proxy curves (aligning using the very limited age control to test if entrenchment events are coincident with climatic changes. Channel incision along one of the traces in Lorca-Totana segment may be related to transitions from glacial to interglacial periods.

  6. Recent Progress on Modeling Slip Deformation in Shape Memory Alloys

    Science.gov (United States)

    Sehitoglu, H.; Alkan, S.

    2018-03-01

    This paper presents an overview of slip deformation in shape memory alloys. The performance of shape memory alloys depends on their slip resistance often quantified through the Critical Resolved Shear Stress (CRSS) or the flow stress. We highlight previous studies that identify the active slip systems and then proceed to show how non- Schmid effects can be dominant in shape memory slip behavior. The work is mostly derived from our recent studies while we highlight key earlier works on slip deformation. We finally discuss the implications of understanding the role of slip on curtailing the transformation strains and also the temperature range over which superelasticity prevails.

  7. Recent Progress on Modeling Slip Deformation in Shape Memory Alloys

    Science.gov (United States)

    Sehitoglu, H.; Alkan, S.

    2018-03-01

    This paper presents an overview of slip deformation in shape memory alloys. The performance of shape memory alloys depends on their slip resistance often quantified through the Critical Resolved Shear Stress (CRSS) or the flow stress. We highlight previous studies that identify the active slip systems and then proceed to show how non-Schmid effects can be dominant in shape memory slip behavior. The work is mostly derived from our recent studies while we highlight key earlier works on slip deformation. We finally discuss the implications of understanding the role of slip on curtailing the transformation strains and also the temperature range over which superelasticity prevails.

  8. Multiparameter Monitoring and Prevention of Fault-Slip Rock Burst

    OpenAIRE

    Hu, Shan-chao; Tan, Yun-liang; Ning, Jian-guo; Guo, Wei-Yao; Liu, Xue-sheng

    2017-01-01

    Fault-slip rock burst is one type of the tectonic rock burst during mining. A detailed understanding of the precursory information of fault-slip rock burst and implementation of monitoring and early warning systems, as well as pressure relief measures, are essential to safety production in deep mines. This paper first establishes a mechanical model of stick-slip instability in fault-slip rock bursts and then reveals the failure characteristics of the instability. Then, change rule of mining-i...

  9. Boundary Slip and Surface Interaction: A Lattice Boltzmann Simulation

    International Nuclear Information System (INIS)

    Yan-Yan, Chen; Hua-Bing, Li; Hou-Hui, Yi

    2008-01-01

    The factors affecting slip length in Couette geometry flows are analysed by means of a two-phase mesoscopic lattice Boltzmann model including non-ideal fluid-fluid and fluid-wall interactions. The main factors influencing the boundary slip are the strength of interactions between fluid-fluid and fluid-wall particles. Other factors, such as fluid viscosity, bulk pressure may also change the slip length. We find that boundary slip only occurs under a certain density (bulk pressure). If the density is large enough, the slip length will tend to zero. In our simulations, a low density layer near the wall does not need to be postulated a priori but emerges naturally from the underlying non-ideal mesoscopic dynamics. It is the low density layer that induces the boundary slip. The results may be helpful to understand recent experimental observations on the slippage of micro flows

  10. Analysis of P and Pdiff Coda Arrivals for Water Reverberations to Evaluate Shallow Slip Extent in Large Megathrust Earthquakes

    Science.gov (United States)

    Rhode, A.; Lay, T.

    2017-12-01

    Determining the up-dip rupture extent of large megathrust ruptures is important for understanding their tsunami excitation, frictional properties of the shallow megathrust, and potential for separate tsunami earthquake occurrence. On land geodetic data have almost no resolution of the up-dip extent of faulting and teleseismic observations have limited resolution that is strongly influenced by typically poorly known shallow seismic velocity structure near the toe of the accretionary prism. The increase in ocean depth as slip on the megathrust approaches the trench has significant influence on the strength and azimuthal distribution of water reverberations in the far-field P wave coda. For broadband P waves from large earthquakes with dominant signal periods of about 10 s, water reverberations generated by shallow fault slip under deep water may persist for over a minute after the direct P phases have passed, giving a clear signal of slip near the trench. As the coda waves can be quickly evaluated following the P signal, recognition of slip extending to the trench and associated enhanced tsunamigenic potential could be achieved within a few minutes after the P arrival, potentially contributing to rapid tsunami hazard assessment. We examine the broadband P wave coda at distances from 80 to 120° for a large number of recent major and great earthquakes with independently determined slip distributions and known tsunami excitation to evaluate the prospect for rapidly constraining up-dip rupture extent of large megathrust earthquakes. Events known to have significant shallow slip, at least locally extending to the trench (e.g., 2016 Illapel, Chile; 2010 Maule, 2010 Mentawai) do have relatively enhanced coda levels at all azimuths, whereas events that do not rupture the shallow megathrust (e.g., 2007 Sumatra, 2014 Iquique, 2003 Hokkaido) do not. Some events with slip models lacking shallow slip show strong coda generation, raising questions about the up-dip resolution of

  11. Asymmetrical slip propensity: required coefficient of friction.

    Science.gov (United States)

    Seo, Jung-suk; Kim, Sukwon

    2013-07-31

    Most studies in performing slips and falls research reported their results after the ipsilateral leg of subjects (either right foot or left foot) was guided to contact the contaminated floor surface although many studies indicated concerns for asymmetries of legs in kinematic or kinetic variables. Thus, the present study evaluated if dominant leg's slip tendency would be different from non-dominant leg's slip tendency by comparing the Required Coefficient of Friction (RCOF) of the two lower limbs. Forty seven health adults participated in the present study. RCOF was measured when left or right foot of subjects contacted the force platforms respectively. Paired t-test was performed to test if RCOF and heel velocity (HCV) of dominant legs was different from that of non-dominant legs. It was suggested that the asymmetry in RCOFs and HCV between the two lower limbs existed. The RCOFs of non-dominant legs were higher than that of dominant legs. The results indicated that asymmetry in slip propensity, RCOF, was existed in lower extremity. The results from the study suggested that it would be benefit to include a variable, such as asymmetry, in slips and falls research.

  12. The Slip Behavior and Source Parameters for Spontaneous Slip Events on Rough Faults Subjected to Slow Tectonic Loading

    Science.gov (United States)

    Tal, Yuval; Hager, Bradford H.

    2018-02-01

    We study the response to slow tectonic loading of rough faults governed by velocity weakening rate and state friction, using a 2-D plane strain model. Our numerical approach accounts for all stages in the seismic cycle, and in each simulation we model a sequence of two earthquakes or more. We focus on the global behavior of the faults and find that as the roughness amplitude, br, increases and the minimum wavelength of roughness decreases, there is a transition from seismic slip to aseismic slip, in which the load on the fault is released by more slip events but with lower slip rate, lower seismic moment per unit length, M0,1d, and lower average static stress drop on the fault, Δτt. Even larger decreases with roughness are observed when these source parameters are estimated only for the dynamic stage of the rupture. For br ≤ 0.002, the source parameters M0,1d and Δτt decrease mutually and the relationship between Δτt and the average fault strain is similar to that of a smooth fault. For faults with larger values of br that are completely ruptured during the slip events, the average fault strain generally decreases more rapidly with roughness than Δτt.

  13. Observing and modeling the spectrum of a slow slip event: Constraints on the scaling of slow slip and tremor

    Science.gov (United States)

    Hawthorne, J. C.; Bartlow, N. M.; Ghosh, A.

    2017-12-01

    We estimate the normalized moment rate spectrum of a slow slip event in Cascadia and then attempt to reproduce it. Our goal is to further assess whether a single physical mechanism could govern slow slip and tremor events, with durations that span 6 orders of magnitude, so we construct the spectrum by parameterizing a large slow slip event as the sum of a number of subevents with various durations. The spectrum estimate uses data from three sources: the GPS-based slip inversion of Bartlow et al (2011), PBO borehole strain measurements, and beamforming-based tremor moment estimates of Ghosh et al (2009). We find that at periods shorter than 1 day, the moment rate power spectrum decays as frequencyn, where n is between 0.7 and 1.4 when measured from strain and between 1.2 and 1.4 when inferred from tremor. The spectrum appears roughly flat at periods of 1 to 10 days, as both the 1-day-period strain and tremor data and the 6-day-period slip inversion data imply a moment rate power of 0.02 times the the total moment squared. We demonstrate one way to reproduce this spectrum: by constructing the large-scale slow slip event as the sum of a series of subevents. The shortest of these subevents could be interpreted as VLFEs or even LFEs, while longer subevents might represent the aseismic slip that drives rapid tremor reverals, streaks, or rapid tremor migrations. We pick the subevent magnitudes from a Gutenberg-Richter distribution and place the events randomly throughout a 30-day interval. Then we assign each subevent a duration that scales with its moment to a specified power. Finally, we create a moment rate function for each subevent and sum all of the moment rates. We compute the summed slow slip moment rate spectra with two approaches: a time-domain numerical computation and a frequency-domain analytical summation. Several sets of subevent parameters can allow the constructed slow slip event to match the observed spectrum. One allowable set of parameters is of

  14. New insights into Late Quaternary slip rate of the thrust fault zone, northern margin of the Qilian Shan, NE Tibet

    Science.gov (United States)

    Hai-bo, Y.; Yang, X., Sr.; LI, A.; Huang, X.; Huang, W.

    2017-12-01

    mainly controlled by the eastward extrusion of material along the left-lateral Haiyuan strike-slip Fault.

  15. Learning and Prediction of Slip from Visual Information

    Science.gov (United States)

    Angelova, Anelia; Matthies, Larry; Helmick, Daniel; Perona, Pietro

    2007-01-01

    This paper presents an approach for slip prediction from a distance for wheeled ground robots using visual information as input. Large amounts of slippage which can occur on certain surfaces, such as sandy slopes, will negatively affect rover mobility. Therefore, obtaining information about slip before entering such terrain can be very useful for better planning and avoiding these areas. To address this problem, terrain appearance and geometry information about map cells are correlated to the slip measured by the rover while traversing each cell. This relationship is learned from previous experience, so slip can be predicted remotely from visual information only. The proposed method consists of terrain type recognition and nonlinear regression modeling. The method has been implemented and tested offline on several off-road terrains including: soil, sand, gravel, and woodchips. The final slip prediction error is about 20%. The system is intended for improved navigation on steep slopes and rough terrain for Mars rovers.

  16. Seismic and Aseismic Slip on the Cascadia Megathrust

    Science.gov (United States)

    Michel, S. G. R. M.; Gualandi, A.; Avouac, J. P.

    2017-12-01

    Our understanding of the dynamics governing aseismic and seismic slip hinges on our ability to image the time evolution of fault slip during and in between earthquakes and transients. Such kinematic descriptions are also pivotal to assess seismic hazard as, on the long term, elastic strain accumulating around a fault should be balanced by elastic strain released by seismic slip and aseismic transients. In this presentation, we will discuss how such kinematic descriptions can be obtained from the analysis and modelling of geodetic time series. We will use inversion methods based on Independent Component Analysis (ICA) decomposition of the time series to extract and model the aseismic slip (afterslip and slow slip events). We will show that this approach is very effective to identify, and filter out, non-tectonic sources of geodetic strain such as the strain due to surface loads, which can be estimated using gravimetric measurements from GRACE, and thermal strain. We will discuss in particular the application to the Cascadia subduction zone.

  17. Transformation of fault slip modes in laboratory experiments

    Science.gov (United States)

    Martynov, Vasilii; Alexey, Ostapchuk; Markov, Vadim

    2017-04-01

    Slip mode of crust fault can vary because of many reasons. It's well known that fault structure, material of fault gouge, pore fluid et al. in many ways determines slip modes from creep and slow slip events to mega-earthquakes [1-3]. Therefore, the possibility of fault slip transformation due to external action is urgent question. There is popular and developing approach of fluid injection into central part of fault. The phenomenon of earthquakes induced due to pumping of water was investigated on small and large scales [4, 5]. In this work the laboratory experiments were conducted to study the evolution of the experimental fault slip when changing the properties of the interstitial fluid. The scheme of experiments is the classical slider-model set-up, in which the block under the shear force slips along the interface. In our experiments the plexiglas block 8x8x3 cm3 in size was put on the plexiglas base. The contact of the blocks was filled with a thin layer (about 3 mm thick) of a granular material. The normal load varied from 31 to 156 kPa. The shear load was applied through a spring with stiffness 60 kN/m, and the rate of spring deformation was 20 or 5 mcm/s. Two parameters were recorded during experiments: the shear force acting on the upper block (with an accuracy of 1 N) and its displacement relatively the base (with an accuracy of 0.1 μm). The gouge was composed of quartz sand (97.5%) and clay (2.5%). As a moisturizer were used different fluids with viscosity varying from 1 to 103 mPa x s. Different slip modes were simulated during slider-experiments. In our experiments slip mode is the act of instability manifested in an increase of slip velocity and a drop of shear stress acting on a movable block. The amplitude of a shear stress drop and the peak velocity of the upper block were chosen as the characteristics of the slip mode. In the laboratory experiments, slip events of one type can be achieved either as regularly recurring (regular mode) or as random

  18. Development of microsized slip sensors using dielectric elastomer for incipient slippage

    Science.gov (United States)

    Hwang, Do-Yeon; Kim, Baek-chul; Cho, Han-Jeong; Li, Zhengyuan; Lee, Youngkwan; Nam, Jae-Do; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, J. C.

    2014-04-01

    A humanoid robot hand has received significant attention in various fields of study. In terms of dexterous robot hand, slip detecting tactile sensor is essential to grasping objects safely. Moreover, slip sensor is useful in robotics and prosthetics to improve precise control during manipulation tasks. In this paper, sensor based-human biomimetic structure is fabricated. We reported a resistance tactile sensor that enables to detect a slip on the surface of sensor structure. The resistance slip sensor that the novel developed uses acrylonitrile-butadiene rubber (NBR) as a dielectric substrate and carbon particle as an electrode material. The presented sensor device in this paper has fingerprint-like structures that are similar with the role of the human's finger print. It is possible to measure the slip as the structure of sensor makes a deformation and it changes the resistance through forming a new conductive route. To verify effectiveness of the proposed slip detection, experiment using prototype of resistance slip sensor is conducted with an algorithm to detect slip and slip was successfully detected. In this paper, we will discuss the slip detection properties so four sensor and detection principle.

  19. Factors associated with worker slipping in limited-service restaurants.

    Science.gov (United States)

    Courtney, Theodore K; Verma, Santosh K; Huang, Yueng-Hsiang; Chang, Wen-Ruey; Li, Kai Way; Filiaggi, Alfred J

    2010-02-01

    Slips, trips and falls (STF) are responsible for a substantial injury burden in the global workplace. Restaurant environments are challenged by STF. This study assessed individual and work environment factors related to slipping in US limited-service restaurant workers. Workers in 10 limited-service restaurants in Massachusetts were recruited to participate. Workers' occupational slip and/or fall history within the past 4 weeks was collected by multilingual written questionnaires. Age, gender, job tenure, work hours per week and work shift were also collected. Shoe type, condition and gross shoe contamination were visually assessed. Floor friction was measured and each restaurant's overall mean coefficient of friction (COF) was calculated. The logistic generalised estimating equations model was used to compute adjusted odds ratios (OR). Of 125 workers, 42 reported one or more slips in the past 4 weeks with two reporting a resultant fall. Results from multivariable regression showed that higher restaurant mean COF was significantly associated with a decreased risk of self-reported slipping (OR 0.59, 95% CI 0.42 to 0.82). From the highest to the lowest COF restaurant, the odds of a positive slip history increased by a factor of more than seven. Younger age, male gender, lower weekly work hours and the presence of gross contamination on worker's shoe sole were also associated with increased odds of slip history. Published findings of an association between friction and slipping and falling in actual work environments are rare. The findings suggest that effective intervention strategies to reduce the risk of slips and falls in restaurant workers could include increasing COF and improving housekeeping practices.

  20. Nanomechanics of slip avalanches in amorphous plasticity

    Science.gov (United States)

    Cao, Penghui; Dahmen, Karin A.; Kushima, Akihiro; Wright, Wendelin J.; Park, Harold S.; Short, Michael P.; Yip, Sidney

    2018-05-01

    Discrete stress relaxations (slip avalanches) in a model metallic glass under uniaxial compression are studied using a metadynamics algorithm for molecular simulation at experimental strain rates. The onset of yielding is observed at the first major stress drop, accompanied, upon analysis, by the formation of a single localized shear band region spanning the entire system. During the elastic response prior to yielding, low concentrations of shear transformation deformation events appear intermittently and spatially uncorrelated. During serrated flow following yielding, small stress drops occur interspersed between large drops. The simulation results point to a threshold value of stress dissipation as a characteristic feature separating major and minor avalanches consistent with mean-field modeling analysis and mechanical testing experiments. We further interpret this behavior to be a consequence of a nonlinear interplay of two prevailing mechanisms of amorphous plasticity, thermally activated atomic diffusion and stress-induced shear transformations, originally proposed by Spaepen and Argon, respectively. Probing the atomistic processes at widely separate strain rates gives insight to different modes of shear band formation: percolation of shear transformations versus crack-like propagation. Additionally a focus on crossover avalanche size has implications for nanomechanical modeling of spatially and temporally heterogeneous dynamics.

  1. A bird strike handbook for base-level managers

    Science.gov (United States)

    Payson, R. P.; Vance, J. D.

    1984-09-01

    To help develop more awareness about bird strikes and bird strike reduction techniques, this thesis compiled all relevant information through an extensive literature search, review of base-level documents, and personal interviews. The final product--A Bird Strike Handbook for Base-Level Managers--provides information on bird strike statistics, methods to reduce the strike hazards, and means to obtain additional assistance. The handbook is organized for use by six major base agencies: Maintenance, Civil Engineering, Operations, Air Field Management, Safety, and Air Traffic Control. An appendix follows at the end.

  2. Performance analysis of a microcontroller based slip power recovery ...

    African Journals Online (AJOL)

    Slip power recovery wound rotor induction motor drives are used in high power, limited speed range applications where control of slip power provides the variable speed drive system. In this paper, the steady state performance analysis of conventional slip power recovery scheme using static line commutated inverter in the ...

  3. Vaporization of fault water during seismic slip

    Science.gov (United States)

    Chen, Jianye; Niemeijer, André R.; Fokker, Peter A.

    2017-06-01

    Laboratory and numerical studies, as well as field observations, indicate that phase transitions of pore water might be an important process in large earthquakes. We present a model of the thermo-hydro-chemo-mechanical processes, including a two-phase mixture model to incorporate the phase transitions of pore water, occurring during fast slip (i.e., a natural earthquake) in order to investigate the effects of vaporization on the coseismic slip. Using parameters from typical natural faults, our modeling shows that vaporization can indeed occur at the shallow depths of an earthquake, irrespective of the wide variability of the parameters involved (sliding velocity, friction coefficient, gouge permeability and porosity, and shear-induced dilatancy). Due to the fast kinetics, water vaporization can cause a rapid slip weakening even when the hydrological conditions of the fault zone are not favorable for thermal pressurization, e.g., when permeability is high. At the same time, the latent heat associated with the phase transition causes the temperature rise in the slip zone to be buffered. Our parametric analyses reveal that the amount of frictional work is the principal factor controlling the onset and activity of vaporization and that it can easily be achieved in earthquakes. Our study shows that coseismic pore fluid vaporization might have played important roles at shallow depths of large earthquakes by enhancing slip weakening and buffering the temperature rise. The combined effects may provide an alternative explanation for the fact that low-temperature anomalies were measured in the slip zones at shallow depths of large earthquakes.

  4. Half-cycle slip activity of persistent slip bands at different stages of fatigue life of polycrystalline nickel

    Czech Academy of Sciences Publication Activity Database

    Weidner, A.; Man, Jiří; Tirschler, W.; Klapetek, P.; Blochwitz, C.; Polák, Jaroslav; Skrotzki, W.

    2008-01-01

    Roč. 492, č. 1-2 (2008), s. 118-127 ISSN 0921-5093 R&D Projects: GA ČR GA106/06/1096 Institutional research plan: CEZ:AV0Z20410507 Keywords : persistent slip band * slip activity * half-cycle deformation * atomic force microscopy * scanning electron microscopy * nickel Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.806, year: 2008

  5. Decreasing Slip Rates From 12.8 Ma to Present on the Solitario Canyon Fault at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    D. Buesch

    2006-01-01

    The Solitario Canyon fault, which bounds the west side of Yucca Mountain, Nevada, is the closest fault with Quaternary offset adjacent to the proposed spent nuclear fuel and high-level radioactive waste repository. Dip-slip offset between 12.8 and 10.7 Ma is determined from lithostratigraphic displacement in boreholes USW H-3 and USW WT-7, drilled in the footwall and hanging wall, respectively. The base of the 12.8-Ma Topopah Spring Tuff is interpreted to have 463.3 m of separation across the fault, an average dip slip rate of 0.036 mm/yr. Previous researchers identified a geothermal system active from 11.5 to 10.0 Ma with peak activity at 10.7 Ma that resulted in pervasive alteration of vitric rock to zeolitic minerals where the rocks were in the ground-water saturated zone. The contact between vitric (V) and pervasively zeolitic (Z) rocks cuts across the lithostratigraphic section and offset of this V-Z boundary can be used to measure slip rates between 12.8 and 10.7 Ma. In H-3, the V-Z boundary is 138.4 m below the base of the vitric, densely welded subzone of the Topopah Spring Tuff (Tptpv3). In WT-7, although the V-Z boundary is identified at the base of the Tptpv3, borehole video, cuttings, and geophysical log data indicate the Tptpv3 has well-developed zeolitic alteration along fractures, and this implies 19.5 m of the total thickness of Tptpv3 (and probably additional overlying crystallized rocks) also were in the saturated zone by 10.7 Ma. The V-Z relations across the Solitario Canyon fault in H-3 and WT-7 indicate a minimum of 157.9 m of separation before 10.7 Ma, which is 34.1 percent of the total slip of the Topopah Spring Tuff, and a minimum dip slip rate of 0.075 mm/yr from 12.8 to 10.7 Ma. These data are consistent with the broader structural history of the area near Yucca Mountain. Previous workers used angular unconformities, tilting of structural blocks, and paleomagnetic data to constrain the main period of extensional faulting between 12.7 and 8

  6. Constraining the roughness degree of slip heterogeneity

    KAUST Repository

    Causse, Mathieu

    2010-05-07

    This article investigates different approaches for assessing the degree of roughness of the slip distribution of future earthquakes. First, we analyze a database of slip images extracted from a suite of 152 finite-source rupture models from 80 events (Mw = 4.1–8.9). This results in an empirical model defining the distribution of the slip spectrum corner wave numbers (kc) as a function of moment magnitude. To reduce the “epistemic” uncertainty, we select a single slip model per event and screen out poorly resolved models. The number of remaining models (30) is thus rather small. In addition, the robustness of the empirical model rests on a reliable estimation of kc by kinematic inversion methods. We address this issue by performing tests on synthetic data with a frequency domain inversion method. These tests reveal that due to smoothing constraints used to stabilize the inversion process, kc tends to be underestimated. We then develop an alternative approach: (1) we establish a proportionality relationship between kc and the peak ground acceleration (PGA), using a k−2 kinematic source model, and (2) we analyze the PGA distribution, which is believed to be better constrained than slip images. These two methods reveal that kc follows a lognormal distribution, with similar standard deviations for both methods.

  7. Inferences about the local stress field from focal mechanisms: Applications to earthquakes in the southern Great Basin of Nevada

    International Nuclear Information System (INIS)

    Harmsen, S.C.; Rogers, A.M.

    1986-01-01

    Focal mechanisms determined from regional-network earthquake data or aftershock field investigation often contain members ranging from strike slip to normal slip in extensional tectonic environments or from strike slip to thrust slip in compressional environments. Although the coexistence of normal and strike-slip faulting has suggested to some investigators that the maximum and intermediate principal stresses are of approximately equal magnitude, several have asserted that the directions of principle stresses can or must interchange to accommodate both types of mechanisms (Zoback and Zoback 1980b; Vetter and Ryall, 1983). A Coulomb-Navier criterion of slip is invoked to demonstrate that both types of mechanisms, as well as oblique members having preferred nodal-plane dips intermediate between those of the strike-slip and normal mechanisms, may be observed in a region where the stress field, resolved into principal components, is axially symmetric. The proximate coexistence of earthquakes having diverse focal mechanisms could be interpreted as evidence for an approximately axially symmetric stress field in a region where optimally oriented planes of weakness are known to exist in the host rock. 10 refs., 6 figs

  8. Simulating spontaneous aseismic and seismic slip events on evolving faults

    Science.gov (United States)

    Herrendörfer, Robert; van Dinther, Ylona; Pranger, Casper; Gerya, Taras

    2017-04-01

    Plate motion along tectonic boundaries is accommodated by different slip modes: steady creep, seismic slip and slow slip transients. Due to mainly indirect observations and difficulties to scale results from laboratory experiments to nature, it remains enigmatic which fault conditions favour certain slip modes. Therefore, we are developing a numerical modelling approach that is capable of simulating different slip modes together with the long-term fault evolution in a large-scale tectonic setting. We extend the 2D, continuum mechanics-based, visco-elasto-plastic thermo-mechanical model that was designed to simulate slip transients in large-scale geodynamic simulations (van Dinther et al., JGR, 2013). We improve the numerical approach to accurately treat the non-linear problem of plasticity (see also EGU 2017 abstract by Pranger et al.). To resolve a wide slip rate spectrum on evolving faults, we develop an invariant reformulation of the conventional rate-and-state dependent friction (RSF) and adapt the time step (Lapusta et al., JGR, 2000). A crucial part of this development is a conceptual ductile fault zone model that relates slip rates along discrete planes to the effective macroscopic plastic strain rates in the continuum. We test our implementation first in a simple 2D setup with a single fault zone that has a predefined initial thickness. Results show that deformation localizes in case of steady creep and for very slow slip transients to a bell-shaped strain rate profile across the fault zone, which suggests that a length scale across the fault zone may exist. This continuum length scale would overcome the common mesh-dependency in plasticity simulations and question the conventional treatment of aseismic slip on infinitely thin fault zones. We test the introduction of a diffusion term (similar to the damage description in Lyakhovsky et al., JMPS, 2011) into the state evolution equation and its effect on (de-)localization during faster slip events. We compare

  9. Tremor-genic slow slip regions may be deeper and warmer and may slip slower than non-tremor-genic regions

    Science.gov (United States)

    Montgomery-Brown, Emily; Syracuse, Ellen M.

    2015-01-01

    Slow slip events (SSEs) are observed worldwide and often coincide with tectonic tremor. Notable examples of SSEs lacking observed tectonic tremor, however, occur beneath Kīlauea Volcano, Hawaii, the Boso Peninsula, Japan, near San Juan Bautista on the San Andreas Fault, California, and recently in Central Ecuador. These SSEs are similar to other worldwide SSEs in many ways (e.g., size or duration), but lack the concurrent tectonic tremor observed elsewhere; instead, they trigger swarms of regular earthquakes. We investigate the physical conditions that may distinguish these non-tremor-genic SSEs from those associated with tectonic tremor, including slip velocity, pressure, temperature, fluids, and fault asperities, although we cannot eliminate the possibility that tectonic tremor may be obscured in highly attenuating regions. Slip velocities of SSEs at Kīlauea Volcano (∼10−6 m/s) and Boso Peninsula (∼10−7 m/s) are among the fastest SSEs worldwide. Kīlauea Volcano, the Boso Peninsula, and Central Ecuador are also among the shallowest SSEs worldwide, and thus have lower confining pressures and cooler temperatures in their respective slow slip zones. Fluids also likely contribute to tremor generation, and no corresponding zone of high vp/vs has been noted at Kīlauea or Boso. We suggest that the relatively faster slip velocities at Kīlauea Volcano and the Boso Peninsula result from specific physical conditions that may also be responsible for triggering swarms of regular earthquakes adjacent to the slow slip, while different conditions produce slower SSE velocities elsewhere and trigger tectonic tremor.

  10. Characterizing the potential for fault reactivation related to CO2 injection through subsurface structural mapping and stress field analysis, Wellington Field, Sumner County, KS

    Science.gov (United States)

    Schwab, D.; Bidgoli, T.; Taylor, M. H.

    2015-12-01

    South-central Kansas has experienced an unprecedented increase in seismic activity since 2013. The spatial and temporal relationship of the seismicity with brine disposal operations has renewed interest in the role of fluids in fault reactivation. This study focuses on determining the suitability of CO2 injection into a Cambro-Ordovician reservoir for long-term storage and a Mississippian reservoir for enhanced oil recovery in Wellington Field, Sumner County, Kansas. Our approach for determining the potential for induced seismicity has been to (1) map subsurface faults and estimate in-situ stresses, (2) perform slip and dilation tendency analysis to identify optimally-oriented faults relative to the estimated stress field, and (3) monitor surface deformation through cGPS data and InSAR imaging. Through the use of 3D seismic reflection data, 60 near vertical, NNE-striking faults have been identified. The faults range in length from 140-410 m and have vertical separations of 3-32m. A number of faults appear to be restricted to shallow intervals, while others clearly cut the top basement reflector. Drilling-induced tensile fractures (N=78) identified from image logs and inversion of earthquake focal mechanism solutions (N=54) are consistent with the maximum horizontal stress (SHmax) oriented ~E-W. Both strike-slip and normal-slip fault plane solutions for earthquakes near the study area suggest that SHmax and Sv may be similar in magnitude. Estimates of stress magnitudes using step rate tests (Shmin = 2666 psi), density logs (Sv = 5308 psi), and calculations from wells with drilling induced tensile fractures (SHmax = 4547-6655 psi) are determined at the gauge depth of 4869ft. Preliminary slip and dilation tendency analysis indicates that faults striking 0°-20° are stable, whereas faults striking 26°-44° may have a moderate risk for reactivation with increasing pore-fluid pressure.

  11. Geometry and Kinematics of the Lopukangri Fault System: Implications for Internal Deformation of the Tibetan Plateau

    Science.gov (United States)

    Murphy, M. A.; Taylor, M. H.

    2006-12-01

    We present geologic mapping and structural data from the Lopukangri fault system in south-central Tibet that sheds light on the geometry, kinematics and spatial characteristics of deformation in western Tibet and the western Himalaya. The Lopukangri fault system strikes N09E and extends 150 km from the Lhasa terrane into the Tethyan fold-thrust belt at 84.5° N. Geologic mapping shows that the deformation is accommodated by a northwest dipping oblique fault system, which accommodates both right-lateral and normal dip-slip movement, consistent with right-lateral separations of Quaternary surficial deposits. The fault system juxtaposes amphibolite-grade rocks in its footwall against greenschist-grade rocks in its hanging wall. Deformation is distributed over a 4 km wide zone that predominately records right-lateral normal slip in ductile and brittle shear fabrics. The fault system right-laterally separates the Gangdese batholith, Kailas conglomerate, Great Counter thrust, and the Tethyan fold-thrust belt for 15 km. Age estimates of the Kailas conglomerate in the Kailas region implies that the Lopukangri fault system initiated after the Early Miocene( 23Ma). The observation that the Lopukangri fault system cuts the Indus-Yaly suture zone, rules out active strike-slip faulting along it at this locality. To assess the role of the Lopukangri fault system in accommodating strain within western Tibet, we compare our results with fault-slip data and structural geometries from the Karakoram and Dangardzong (Thakkhola graben) fault systems. The Dangardzong fault shares similar kinematics with the Lopukangri fault system, both display a significant component of right-slip. Although the two faults do not strike into one another, they may be linked via a transfer zone. The Karakoram fault accommodates right-lateral slip in which a portion of the total slip extends from the Tibetan plateau into the Himalayan thrust belt via right-stepover structures. Fault slip data from the

  12. Slip flow in graphene nanochannels

    DEFF Research Database (Denmark)

    . Kannam, Sridhar; Billy, Todd; Hansen, Jesper Schmidt

    2011-01-01

    We investigate the hydrodynamic boundary condition for simple nanofluidic systems such as argon and methane flowing in graphene nanochannels using equilibrium molecular dynamics simulations (EMD) in conjunction with our recently proposed method [J. S. Hansen, B. D. Todd, and P. J. Daivis, Phys. Rev....... E 84, 016313 (2011)10.1103/PhysRevE.84.016313]. We first calculate the fluid-graphene interfacial friction coefficient, from which we can predict the slip length and the average velocity of the first fluid layer close to the wall (referred to as the slip velocity). Using direct nonequilibrium...

  13. Predicting timing of foot strike during running, independent of striking technique, using principal component analysis of joint angles.

    Science.gov (United States)

    Osis, Sean T; Hettinga, Blayne A; Leitch, Jessica; Ferber, Reed

    2014-08-22

    As 3-dimensional (3D) motion-capture for clinical gait analysis continues to evolve, new methods must be developed to improve the detection of gait cycle events based on kinematic data. Recently, the application of principal component analysis (PCA) to gait data has shown promise in detecting important biomechanical features. Therefore, the purpose of this study was to define a new foot strike detection method for a continuum of striking techniques, by applying PCA to joint angle waveforms. In accordance with Newtonian mechanics, it was hypothesized that transient features in the sagittal-plane accelerations of the lower extremity would be linked with the impulsive application of force to the foot at foot strike. Kinematic and kinetic data from treadmill running were selected for 154 subjects, from a database of gait biomechanics. Ankle, knee and hip sagittal plane angular acceleration kinematic curves were chained together to form a row input to a PCA matrix. A linear polynomial was calculated based on PCA scores, and a 10-fold cross-validation was performed to evaluate prediction accuracy against gold-standard foot strike as determined by a 10 N rise in the vertical ground reaction force. Results show 89-94% of all predicted foot strikes were within 4 frames (20 ms) of the gold standard with the largest error being 28 ms. It is concluded that this new foot strike detection is an improvement on existing methods and can be applied regardless of whether the runner exhibits a rearfoot, midfoot, or forefoot strike pattern. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Molecular Dynamics Simulations of Slip on Curved Surfaces

    Directory of Open Access Journals (Sweden)

    Ross D.A.

    2016-07-01

    Full Text Available We present Molecular Dynamics (MD simulations of liquid water confined within nanoscale geometries, including slit-like and cylindrical graphitic pores. These equilibrium results are used for calculating friction coefficients, which in turn can be used to calculate slip lengths. The slip length is a material property independent of the fluid flow rate. It is therefore a better quantity for study than the fluid velocity at the wall, also known as the slip velocity. Once the slip length has been found as a function of surface curvature, it can be used to parameterise Lattice Boltzmann (LB simulations. These larger scale simulations are able to tell us about how fluid transport is affected by slip in complex geometries; not just limited to single pores. Applications include flow and transport in nano-porous engine valve deposits and gas shales. The friction coefficient is found to be a function of curvature and is higher for fluid on convex surfaces and lower for concave surfaces. Both concave and convex surfaces approach the same value of the friction coefficient, which is constant above some critical radius of curvature, here found to be 7.4 ± 2.9 nm. The constant value of the friction coefficient is 10,000 ± 600 kg m−2 s−1, which is equivalent to a slip length of approximately 67 ± 4 nm.

  15. Tiechanshan-Tunghsiao anticline earthquake analysis: Implications for northwestern Taiwan potential carbon dioxide storage site seismic hazard

    Directory of Open Access Journals (Sweden)

    Ruey-Juin Rau

    2017-01-01

    Full Text Available We analyze the seismicity and earthquake focal mechanisms beneath the Tiechanshan-Tunghsiao (TCS-TH anticline over the last two decades for seismic hazard evaluation of a potential carbon dioxide storage site in northwestern Taiwan. Seismicity in the TCS-TH anticline indicates both spatial and temporal clustering at a depth range of 7 - 12 km. Thirteen 3.0 ≤ ML ≤ 5.2 earthquake focal mechanisms show a combination of thrust, strike-slip, and normal faulting mechanisms under the TCS-TH anticline. A 1992 ML 5.2 earthquake with a focal depth of ~10 km, the largest event ever recorded beneath the TCS-TH anticline during the last two decades, has a normal fault mechanism with the T-axis trending NNE-SSW and nodal planes oriented NNW-SSE, dipping either gently to the NNE or steeply to the SSW. Thrust fault mechanisms that occurred with mostly E-W or NWW-SEE striking P-axes and strike-slip faulting events indicate NWW-SEE striking P-axes and NNE-SSW trending T-axes, which are consistent with the regional plate convergence direction. For the strike-slip faulting events, if we take the N-S or NNW-SSE striking nodal planes as the fault planes, the strike-slip faults are sinistral motions and correspond to the Tapingting fault, which is a strike-slip fault reactivated from the inherited normal fault and intersects the Tiechanshan and Tunghsiao anticlines.

  16. Shape fabric development in rigid clast populations under pure shear: The influence of no-slip versus slip boundary conditions

    Science.gov (United States)

    Mulchrone, Kieran F.; Meere, Patrick A.

    2015-09-01

    Shape fabrics of elliptical objects in rocks are usually assumed to develop by passive behavior of inclusions with respect to the surrounding material leading to shape-based strain analysis methods belonging to the Rf/ϕ family. A probability density function is derived for the orientational characteristics of populations of rigid ellipses deforming in a pure shear 2D deformation with both no-slip and slip boundary conditions. Using maximum likelihood a numerical method is developed for estimating finite strain in natural populations deforming for both mechanisms. Application to a natural example indicates the importance of the slip mechanism in explaining clast shape fabrics in deformed sediments.

  17. A Transformational Approach to Slip-Slide Factoring

    Science.gov (United States)

    Steckroth, Jeffrey

    2015-01-01

    In this "Delving Deeper" article, the author introduces the slip-slide method for solving Algebra 1 mathematics problems. This article compares the traditional method approach of trial and error to the slip-slide method of factoring. Tools that used to be taken for granted now make it possible to investigate relationships visually,…

  18. Complex rupture process of the Mw 7.8, 2016, Kaikoura earthquake, New Zealand, and its aftershock sequence

    Science.gov (United States)

    Cesca, S.; Zhang, Y.; Mouslopoulou, V.; Wang, R.; Saul, J.; Savage, M.; Heimann, S.; Kufner, S.-K.; Oncken, O.; Dahm, T.

    2017-11-01

    faults at the northern end of the rupture. The northern and southern strike-slip fault domains have the same orientation but are spatially separated by >15 km. In our model, the low angle splay thrust fault is located above the slab and connects the strike-slip faults kinematically. During the aftershock phase, the entire fault system remained active.

  19. Next generation GNSS single receiver cycle slip reliability

    NARCIS (Netherlands)

    Teunissen, P.J.G.; De Bakker, P.F.

    2009-01-01

    In this contribution we study the multi-frequency, carrier-phase slip detection capabilities of a single receiver. Our analysis is based on an analytical expression that we present for themulti-frequencyminimal detectable carrier phase cycle slip.

  20. Foot strike patterns after obstacle clearance during running.

    Science.gov (United States)

    Scholten, Shane D; Stergiou, Nicholas; Hreljac, Alan; Houser, Jeremy; Blanke, Daniel; Alberts, L Russell

    2002-01-01

    Running over obstacles of sufficient height requires heel strike (HS) runners to make a transition in landing strategy to a forefoot (FF) strike, resulting in similar ground reaction force patterns to those observed while landing from a jump. Identification of the biomechanical variables that distinguish between the landing strategies may offer some insight into the reasons that the transition occurs. The purpose of this study was to investigate the difference in foot strike patterns and kinetic parameters of heel strike runners between level running and running over obstacles of various heights. Ten heel strike subjects ran at their self-selected pace under seven different conditions: unperturbed running (no obstacle) and over obstacles of six different heights (10%, 12.5%, 15%, 17.5%, 20%, and 22.5% of their standing height). The obstacle was placed directly before a Kistler force platform. Repeated measures ANOVAs were performed on the subject means of selected kinetic parameters. The statistical analysis revealed significant differences (P strike patterns were affected by the increased obstacle height. Between the 12.5% and 15% obstacle conditions, the group response changed from a heel strike to a forefoot strike pattern. At height > 15%, the pattern was more closely related to the foot strike patterns found in jumping activities. This strategy change may represent a gait transition effected as a mechanism to protect against increased impact forces. Greater involvement of the ankle and the calf muscles could have assisted in attenuating the increased impact forces while maintaining speed after clearing the obstacle.

  1. Strikes and solidarity: coalfield conflict in Britain, 1889-1966

    Energy Technology Data Exchange (ETDEWEB)

    Roy Church; Quentin Outram [University of East Anglia, Norwich (United Kingdom)

    2002-05-01

    This book investigates the history of strike activity in the British coal mining industry, a byword for industrial militancy since the late nineteenth century. Contents: 1. Interpreting coalfield conflict: focus and formulations; 2. Tradition and modernity: the mining industry 1889-1940; 3. Employers and workers: organizations and strategies; 4. Employers and workers: ideologies, attitudes and political orientations; 5. Configurations of strike activity; 6. Strike participation and solidarity before 1912; 7. Strikes, organization and consciousness in 1912 and after; 8. Conflictual context? The 'isolated mass' revisited; 9. Mining and modernity: size, sectionalism and solidarity; 10. The foundations of strike propensity; 11. Miners and management: agency and action; 12. Industrial relations and strikes after nationalization; 13. International perspectives; 14. Myths and realities: strikes, solidarity and 'militant miners'.

  2. Ultra-thin clay layers facilitate seismic slip in carbonate faults.

    Science.gov (United States)

    Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Di Toro, Giulio; Spagnuolo, Elena; Zorzi, Federico

    2017-04-06

    Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms -1 ) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms -1 ), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.

  3. Stress sensitivity of fault seismicity: A comparison between limited-offset oblique and major strike-slip faults

    Science.gov (United States)

    Parsons, T.; Stein, R.S.; Simpson, R.W.; Reasenberg, P.A.

    1999-01-01

    We present a new three-dimensional inventory of the southern San Francisco Bay area faults and use it to calculate stress applied principally by the 1989 M = 7.1 Loma Prieta earthquake and to compare fault seismicity rates before and after 1989. The major high-angle right-lateral faults exhibit a different response to the stress change than do minor oblique (right-lateral/thrust) faults. Seismicity on oblique-slip faults in the southern Santa Clara Valley thrust belt increased where the faults were unclamped. The strong dependence of seismicity change on normal stress change implies a high coefficient of static friction. In contrast, we observe that faults with significant offset (>50-100 km) behave differently; microseismicity on the Hayward fault diminished where right-lateral shear stress was reduced and where it was unclamped by the Loma Prieta earthquake. We observe a similar response on the San Andreas fault zone in southern California after the Landers earthquake sequence. Additionally, the offshore San Gregorio fault shows a seismicity rate increase where right-lateral/oblique shear stress was increased by the Loma Prieta earthquake despite also being clamped by it. These responses are consistent with either a low coefficient of static friction or high pore fluid pressures within the fault zones. We can explain the different behavior of the two styles of faults if those with large cumulative offset become impermeable through gouge buildup; coseismically pressurized pore fluids could be trapped and negate imposed normal stress changes, whereas in more limited offset faults, fluids could rapidly escape. The difference in behavior between minor and major faults may explain why frictional failure criteria that apply intermediate coefficients of static friction can be effective in describing the broad distributions of aftershocks that follow large earthquakes, since many of these events occur both inside and outside major fault zones.

  4. Continental deformation accommodated by non-rigid passive bookshelf faulting: An example from the Cenozoic tectonic development of northern Tibet

    Science.gov (United States)

    Zuza, Andrew V.; Yin, An

    2016-05-01

    Collision-induced continental deformation commonly involves complex interactions between strike-slip faulting and off-fault deformation, yet this relationship has rarely been quantified. In northern Tibet, Cenozoic deformation is expressed by the development of the > 1000-km-long east-striking left-slip Kunlun, Qinling, and Haiyuan faults. Each have a maximum slip in the central fault segment exceeding 10s to ~ 100 km but a much smaller slip magnitude (~bookshelf-fault model for the Cenozoic tectonic development of northern Tibet. Our model, quantitatively relating discrete left-slip faulting to distributed off-fault deformation during regional clockwise rotation, explains several puzzling features, including the: (1) clockwise rotation of east-striking left-slip faults against the northeast-striking left-slip Altyn Tagh fault along the northwestern margin of the Tibetan Plateau, (2) alternating fault-parallel extension and shortening in the off-fault regions, and (3) eastward-tapering map-view geometries of the Qimen Tagh, Qaidam, and Qilian Shan thrust belts that link with the three major left-slip faults in northern Tibet. We refer to this specific non-rigid bookshelf-fault system as a passive bookshelf-fault system because the rotating bookshelf panels are detached from the rigid bounding domains. As a consequence, the wallrock of the strike-slip faults deforms to accommodate both the clockwise rotation of the left-slip faults and off-fault strain that arises at the fault ends. An important implication of our model is that the style and magnitude of Cenozoic deformation in northern Tibet vary considerably in the east-west direction. Thus, any single north-south cross section and its kinematic reconstruction through the region do not properly quantify the complex deformational processes of plateau formation.

  5. Fore-arc Deformation in the Paola Basin Segment (Offshore Western Calabria) of the Tyrrhenian-Ionian Subduction System

    Science.gov (United States)

    Pepe, F.; Corradino, M.; Nicolich, R.; Barreca, G.; Bertotti, G.; Ferranti, L.; Monaco, C.

    2017-12-01

    The 3D stratigraphic architecture and Late Neogene to Recent tectonic evolution of the Paola Basin (offshore western Calabria), a segment in the fore-arc of the Tyrrhenian-Ionian subduction system, is reconstructed by using a grid of high-penetration reflection seismics. Oligocene to Messinian deposits are interpreted all along the profile. They tend to fossilize preexisting topography and reach the largest thicknesses between (fault controlled) basement highs. Plio-Quaternary deposits are found over the entire area and display variations in thickness and tectonic style. They are thicken up to 4.5 km in the depocenter of the basin, and decrease both in the east and west termination of the lines. The Paola Basin can be partitioned into two sectors with different tectonic deformation, separated by a NNW-SSE elongated area that coincides with the basin depocenter. Tectonic features associated with strike-slip restraining and releasing bends are widely spread over the western sector of the basin. Overall, they form an approximately NS-trending and geomorphically prominent ridge separating the Paola Basin from the Marsili abyssal plain. A high-angle, NNE-trending, normal fault system develops on the south-west tip of the basin, where the faults offset the Messinian horizon of ca. 500 m. Data suggest that limited vertical slip occurs along reverse faults detected at the border and inside the sedimentary infilling of the Paola Basin, reaching thickness of more than 3.8s two way travel time. The reflection sequence pattern can be interpreted as a result of the infilling of the thrust-top basin related to a prograding system, located between a growth ramp-anticline to the west and a culmination of basement-thrust sheets to the East. We propose that the Paola Basin developed near the northern edge of the Ionian slab where tearing of the lithosphere is expected. Also, the strike-slip fault system is a kinematic consequence of obliquely convergent subduction settings, where

  6. Estimating the Impact of Bird Strikes

    NARCIS (Netherlands)

    Metz, I.C.; Muhlhausen, Thorsten; Ellerbroek, J.; Hoekstra, J.M.

    2018-01-01

    Bird strikes have the potential to cause severe damage to aircraft. Therefore, measures to reduce the risk of bird strikes are performed at airports. However, this risk is not limited to the airport but is increased in the arrival and departure corridors as well. Consequently, a significant amount

  7. Improved analysis and visualization of friction loop data: unraveling the energy dissipation of meso-scale stick-slip motion

    Science.gov (United States)

    Kokorian, Jaap; Merlijn van Spengen, W.

    2017-11-01

    In this paper we demonstrate a new method for analyzing and visualizing friction force measurements of meso-scale stick-slip motion, and introduce a method for extracting two separate dissipative energy components. Using a microelectromechanical system tribometer, we execute 2 million reciprocating sliding cycles, during which we measure the static friction force with a resolution of \

  8. Automatic recognition of falls in gait-slip training: Harness load cell based criteria.

    Science.gov (United States)

    Yang, Feng; Pai, Yi-Chung

    2011-08-11

    Over-head-harness systems, equipped with load cell sensors, are essential to the participants' safety and to the outcome assessment in perturbation training. The purpose of this study was to first develop an automatic outcome recognition criterion among young adults for gait-slip training and then verify such criterion among older adults. Each of 39 young and 71 older subjects, all protected by safety harness, experienced 8 unannounced, repeated slips, while walking on a 7m walkway. Each trial was monitored with a motion capture system, bilateral ground reaction force (GRF), harness force, and video recording. The fall trials were first unambiguously indentified with careful visual inspection of all video records. The recoveries without balance loss (in which subjects' trailing foot landed anteriorly to the slipping foot) were also first fully recognized from motion and GRF analyses. These analyses then set the gold standard for the outcome recognition with load cell measurements. Logistic regression analyses based on young subjects' data revealed that the peak load cell force was the best predictor of falls (with 100% accuracy) at the threshold of 30% body weight. On the other hand, the peak moving average force of load cell across 1s period, was the best predictor (with 100% accuracy) separating recoveries with backward balance loss (in which the recovery step landed posterior to slipping foot) from harness assistance at the threshold of 4.5% body weight. These threshold values were fully verified using the data from older adults (100% accuracy in recognizing falls). Because of the increasing popularity in the perturbation training coupling with the protective over-head-harness system, this new criterion could have far reaching implications in automatic outcome recognition during the movement therapy. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. AUTOMATIC RECOGNITION OF FALLS IN GAIT-SLIP: A HARNESS LOAD CELL BASED CRITERION

    Science.gov (United States)

    Yang, Feng; Pai, Yi-Chung

    2012-01-01

    Over-head-harness systems, equipped with load cell sensors, are essential to the participants’ safety and to the outcome assessment in perturbation training. The purpose of this study was to first develop an automatic outcome recognition criterion among young adults for gait-slip training and then verify such criterion among older adults. Each of 39 young and 71 older subjects, all protected by safety harness, experienced 8 unannounced, repeated slips, while walking on a 7-m walkway. Each trial was monitored with a motion capture system, bilateral ground reaction force (GRF), harness force and video recording. The fall trials were first unambiguously indentified with careful visual inspection of all video records. The recoveries without balance loss (in which subjects’ trailing foot landed anteriorly to the slipping foot) were also first fully recognized from motion and GRF analyses. These analyses then set the gold standard for the outcome recognition with load cell measurements. Logistic regression analyses based on young subjects’ data revealed that peak load cell force was the best predictor of falls (with 100% accuracy) at the threshold of 30% body weight. On the other hand, the peak moving average force of load cell across 1-s period, was the best predictor (with 100% accuracy) separating recoveries with backward balance loss (in which the recovery step landed posterior to slipping foot) from harness assistance at the threshold of 4.5% body weight. These threshold values were fully verified using the data from older adults (100% accuracy in recognizing falls). Because of the increasing popularity in the perturbation training coupling with the protective over-head-harness system, this new criterion could have far reaching implications in automatic outcome recognition during the movement therapy. PMID:21696744

  10. Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

    Science.gov (United States)

    van der Werf, Thomas; Chatzaras, Vasileios; Marcel Kriegsman, Leo; Kronenberg, Andreas; Tikoff, Basil; Drury, Martyn R.

    2017-12-01

    The rheology of lower crust and its transient behavior in active strike-slip plate boundaries remain poorly understood. To address this issue, we analyzed a suite of granulite and lherzolite xenoliths from the upper Pleistocene-Holocene San Quintín volcanic field of northern Baja California, Mexico. The San Quintín volcanic field is located 20 km east of the Baja California shear zone, which accommodates the relative movement between the Pacific plate and Baja California microplate. The development of a strong foliation in both the mafic granulites and lherzolites, suggests that a lithospheric-scale shear zone exists beneath the San Quintín volcanic field. Combining microstructural observations, geothermometry, and phase equilibria modeling, we estimated that crystal-plastic deformation took place at temperatures of 750-890 °C and pressures of 400-560 MPa, corresponding to 15-22 km depth. A hot crustal geotherm of 40 ° C km-1 is required to explain the estimated deformation conditions. Infrared spectroscopy shows that plagioclase in the mafic granulites is relatively dry. Microstructures are interpreted to show that deformation in both the uppermost lower crust and upper mantle was accommodated by a combination of dislocation creep and grain-size-sensitive creep. Recrystallized grain size paleopiezometry yields low differential stresses of 12-33 and 17 MPa for plagioclase and olivine, respectively. The lower range of stresses (12-17 MPa) in the mafic granulite and lherzolite xenoliths is interpreted to be associated with transient deformation under decreasing stress conditions, following an event of stress increase. Using flow laws for dry plagioclase, we estimated a low viscosity of 1.1-1.3×1020 Pa ṡ s for the high temperature conditions (890 °C) in the lower crust. Significantly lower viscosities in the range of 1016-1019 Pa ṡ s, were estimated using flow laws for wet plagioclase. The shallow upper mantle has a low viscosity of 5.7×1019 Pa ṡ s

  11. The effect of hand dominance on martial arts strikes.

    Science.gov (United States)

    Neto, Osmar Pinto; Silva, Jansen Henrique; Marzullo, Ana Carolina de Miranda; Bolander, Richard P; Bir, Cynthia A

    2012-08-01

    The main goal of this study was to compare dominant and non-dominant martial arts palm strikes under different circumstances that usually happen during martial arts and combative sports applications. Seven highly experienced (10±5 years) right hand dominant Kung Fu practitioners performed strikes with both hands, stances with left or right lead legs, and with the possibility or not of stepping towards the target (moving stance). Peak force was greater for the dominant hand strikes (1593.76±703.45 N vs. 1042.28±374.16 N; p<.001), whereas no difference was found in accuracy between the hands (p=.141). Additionally, peak force was greater for the strikes with moving stance (1448.75±686.01 N vs. 1201.80±547.98 N; p=.002) and left lead leg stance (1378.06±705.48 N vs. 1269.96±547.08 N). Furthermore, the difference in peak force between strikes with moving and stationary stances was statistically significant only for the strikes performed with a left lead leg stance (p=.007). Hand speed was higher for the dominant hand strikes (5.82±1.08 m/s vs. 5.24±0.78 m/s; p=.001) and for the strikes with moving stance (5.79±1.01 m/s vs. 5.29±0.90 m/s; p<.001). The difference in hand speed between right and left hand strikes was only significant for strikes with moving stance. In summary, our results suggest that the stronger palm strike for a right-handed practitioner is a right hand strike on a left lead leg stance moving towards the target. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Predicting the probability of slip in gait: methodology and distribution study.

    Science.gov (United States)

    Gragg, Jared; Yang, James

    2016-01-01

    The likelihood of a slip is related to the available and required friction for a certain activity, here gait. Classical slip and fall analysis presumed that a walking surface was safe if the difference between the mean available and required friction coefficients exceeded a certain threshold. Previous research was dedicated to reformulating the classical slip and fall theory to include the stochastic variation of the available and required friction when predicting the probability of slip in gait. However, when predicting the probability of a slip, previous researchers have either ignored the variation in the required friction or assumed the available and required friction to be normally distributed. Also, there are no published results that actually give the probability of slip for various combinations of required and available frictions. This study proposes a modification to the equation for predicting the probability of slip, reducing the previous equation from a double-integral to a more convenient single-integral form. Also, a simple numerical integration technique is provided to predict the probability of slip in gait: the trapezoidal method. The effect of the random variable distributions on the probability of slip is also studied. It is shown that both the required and available friction distributions cannot automatically be assumed as being normally distributed. The proposed methods allow for any combination of distributions for the available and required friction, and numerical results are compared to analytical solutions for an error analysis. The trapezoidal method is shown to be highly accurate and efficient. The probability of slip is also shown to be sensitive to the input distributions of the required and available friction. Lastly, a critical value for the probability of slip is proposed based on the number of steps taken by an average person in a single day.

  13. BIRD/WILDLIFE STRIKE CONTROL FOR SAFER AIR ...

    African Journals Online (AJOL)

    Osondu

    2012-06-05

    Jun 5, 2012 ... Keywords: bird/wildlife, strike, aviation, hazard, control. Introduction ... Ethiopian Journal of Environmental Studies and Management EJESM Vol. 5 No. 3 2012 .... Aircraft Bird. Strike Avoidance Rader System (ABARS) and.

  14. Determine the Foot Strike Pattern Using Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Tzyy-Yuang Shiang

    2016-01-01

    Full Text Available From biomechanical point of view, strike pattern plays an important role in preventing potential injury risk in running. Traditionally, strike pattern determination was conducted by using 3D motion analysis system with cameras. However, the procedure is costly and not convenient. With the rapid development of technology, sensors have been applied in sport science field lately. Therefore, this study was designed to determine the algorithm that can identify landing strategies with a wearable sensor. Six healthy male participants were recruited to perform heel and forefoot strike strategies at 7, 10, and 13 km/h speeds. The kinematic data were collected by Vicon 3D motion analysis system and 2 inertial measurement units (IMU attached on the dorsal side of both shoes. The data of each foot strike were gathered for pitch angle and strike index analysis. Comparing the strike index from IMU with the pitch angle from Vicon system, our results showed that both signals exhibited highly correlated changes between different strike patterns in the sagittal plane (r=0.98. Based on the findings, the IMU sensors showed potential capabilities and could be extended beyond the context of sport science to other fields, including clinical applications.

  15. A decade of U.S. Air Force bat strikes

    Science.gov (United States)

    Peurach, Suzanne C.; Dove, Carla J.; Stepko, Laura

    2009-01-01

    From 1997 through 2007, 821 bat strikes were reported to the U.S. Air Force (USAF) Safety Center by aircraft personnel or ground crew and sent to the National Museum of Natural History, Smithsonian Institution, for identification. Many samples were identified by macroscopic and or microscopic comparisons with bat specimens housed in the museum and augmented during the last 2 years by DNA analysis. Bat remains from USAF strikes during this period were received at the museum from 40 states in the United States and from 20 countries. We confirmed that 46% of the strikes were caused by bats, but we did not identify them further; we identified 5% only to the family or genus level, and 49% to the species level. Fifty-five of the 101 bat-strike samples submitted for DNA analysis have been identified to the species level. Twenty-five bat species have been recorded striking USAF planes worldwide. The Brazilian free-tailed bat (Tadarida brasiliensis; n = 173) is the species most commonly identified in USAF strike impacts, followed by the red bat (Lasiurus borealis; n = 83). Bat strikes peak during the spring and fall, with >57% occurring from August through October; 82% of the reports that included time of strike were recorded between 2100 and 0900 hours. More than 12% of the bat strikes were reported at >300 m above ground level (AGL). Although $825,000 and >50% of this sum was attributable to 5 bat-strike incidents. Only 5 bats from the 10 most damaging bat strikes were identified to the species level, either because we did not receive remains with the reports or the sample was insufficient for identification.

  16. Incipient Evolution of the Eastern California Shear Zone through a Transpressional Zone along the San Andreas Fault in the San Bernardino Mountains, California

    Science.gov (United States)

    Cochran, W. J.; Spotila, J. A.

    2017-12-01

    Measuring long-term accumulation of strike-slip displacements and transpressional uplift is difficult where strain is accommodated across wide shear zones, as opposed to a single major fault. The Eastern California Shear Zone (ECSZ) in southern California accommodates dextral shear across several strike-slip faults, and is potentially migrating and cutting through a formerly convergent zone of the San Bernardino Mountains (SBM). The advection of crust along the San Andreas fault to the SE has forced these two tectonic regimes into creating a nexus of interacting strike-slip faults north of San Gorgonio Pass. These elements make this region ideal for studying complex fault interactions, evolving fault geometries, and deformational overprinting within a wide shear zone. Using high-resolution topography and field mapping, this study aims to test whether diffuse, poorly formed strike-slip faults within the uplifted SBM block are nascent elements of the ECSZ. Topographic resolution of ≤ 1m was achieved using both lidar and UAV surveys along two Quaternary strike-slip faults, namely the Lake Peak fault and Lone Valley faults. Although the Lone Valley fault cuts across Quaternary alluvium, the geomorphic expression is obscured, and may be the result of slow slip rates. In contrast, the Lake Peak fault is located high elevations north of San Gorgonio Peak in the SBM, and displaces Quaternary glacial deposits. The deposition of large boulders along the escarpment also obscures the apparent magnitude of slip along the fault. Although determining fault offset is difficult, the Lake Peak fault does display evidence for minor right-lateral displacement, where the magnitude of slip would be consistent with individual faults within the ECSZ (i.e. ≤ 1 mm/yr). Compared to the preservation of displacement along strike-slip faults located within the Mojave Desert, the upland region of the SBM adds complexity for measuring fault offset. The distribution of strain across the entire

  17. Kinematics of Post-obduction Deformation of the Tertiary Ridge at Al-Khod Village (Muscat, Oman

    Directory of Open Access Journals (Sweden)

    Andreas Scharf

    2016-11-01

    Full Text Available Structural investigations in post-obductional Paleocene to Eocene limestones of the Tertiary Ridge reveal a ~1 km long WNW-ESE striking strike-slip fault system within the ridge, consisting of two main sub-parallel, strike-slip faults. Considering the geometry of the Harding Strain Ellipse, the orientation of structures between the two strike-slip faults (e.g., Riedel shears, folds, reverse faults point to left-lateral motion. The abundance of large-scale folds (up to 100 m in wave length and amplitude between the two strike-slip faults led us to the interpretation of transpressive conditions in a first approximation. Moreover, the Tertiary Ridge of the study area consists of three distinct structural domains. The faults of Domain A and C are oriented WNW-ESE, but the trend of the faults in the central Domain B differs by ~10°. The left-lateral strike-slip fault system exists only in Domain B. We propose that the direction of greatest stress during Miocene plate convergence (sigma 1 was oriented 032°/212°. Considering the trend of the strike-slip zone and the orientation of sigma 1, the left-lateral motion must have been transpressive. Sigma 1 is perpendicularly oriented to the domains A and C. Prior to the Miocene D2 compressional event the study area was affected by a D1 extensional event, related to the opening of the Red Sea and the Gulf of Aden or to gravity-driven normal faulting. The D2 compressional/transpressional structures of the Miocene are reactivating the D1 structures of the Oligocene.

  18. 2002 Bird Strike Committee USA/Canada Conference

    National Research Council Canada - National Science Library

    Dolbeer, Richard

    2002-01-01

    Over 380 people from 20 countries and 17 exhibitors attended the 4th annual joint meeting of Bird Strike Committee-USA and Bird Strike Committee Canada in Sacramento, California on October 21-24, 2002...

  19. Slow Slip and Earthquake Nucleation in Meter-Scale Laboratory Experiments

    Science.gov (United States)

    Mclaskey, G.

    2017-12-01

    The initiation of dynamic rupture is thought to be preceded by a quasistatic nucleation phase. Observations of recent earthquakes sometimes support this by illuminating slow slip and foreshocks in the vicinity of the eventual hypocenter. I describe laboratory earthquake experiments conducted on two large-scale loading machines at Cornell University that provide insight into the way earthquake nucleation varies with normal stress, healing time, and loading rate. The larger of the two machines accommodates a 3 m long granite sample, and when loaded to 7 MPa stress levels, we observe dynamic rupture events that are preceded by a measureable nucleation zone with dimensions on the order of 1 m. The smaller machine accommodates a 0.76 m sample that is roughly the same size as the nucleation zone. On this machine, small variations in nucleation properties result in measurable differences in slip events, and we generate both dynamic rupture events (> 0.1 m/s slip rates) and slow slip events ( 0.001 to 30 mm/s slip rates). Slow events occur when instability cannot fully nucleate before reaching the sample ends. Dynamic events occur after long healing times or abrupt increases in loading rate which suggests that these factors shrink the spatial and temporal extents of the nucleation zone. Arrays of slip, strain, and ground motion sensors installed on the sample allow us to quantify seismic coupling and study details of premonitory slip and afterslip. The slow slip events we observe are primarily aseismic (less than 1% of the seismic coupling of faster events) and produce swarms of very small M -6 to M -8 events. These mechanical and seismic interactions suggest that faults with transitional behavior—where creep, small earthquakes, and tremor are often observed—could become seismically coupled if loaded rapidly, either by a slow slip front or dynamic rupture of an earthquake that nucleated elsewhere.

  20. Perception of slipperiness and prospective risk of slipping at work

    Science.gov (United States)

    Courtney, Theodore K; Verma, Santosh K; Chang, Wen-Ruey; Huang, Yueng-Hsiang; Lombardi, David A; Brennan, Melanye J; Perry, Melissa J

    2013-01-01

    Objectives Falls are a leading cause of injury at work, and slipping is the predominant cause of falling. Prior research has suggested a modest correlation between objective measures (such as coefficient of friction, COF) and subjective measures of slipperiness (such as worker perceptions) in the workplace. However, the degree of association between subjective measures and the actual risk of slipping at the workplace is unknown. This study examined the association between perception of slipperiness and the risk of slipping. Methods 475 workers from 36 limited-service restaurants participated in a 12-week prospective cohort study. At baseline, demographic information was collected, participants rated floor slipperiness in eight areas of the restaurant, and work environment factors, such as COF, were measured. Restaurant-level and area-level mean perceptions of slipperiness were calculated. Participants then reported their slip experience at work on a weekly basis for the next 12 weeks. The associations between perception of slipperiness and the rate of slipping were assessed. Results Adjusting for age, gender, body mass index, education, primary language, mean COF, use of slip-resistant shoes, and restaurant chain, each 1-point increase in mean restaurant-level perception of slipperiness (4-point scale) was associated with a 2.71 times increase in the rate of slipping (95% CI 1.25 to 5.87). Results were similar for area-level perception within the restaurant (rate ratios (RR) 2.92, 95% CI 2.41 to 3.54). Conclusions Perceptions of slipperiness and the subsequent rate of slipping were strongly associated. These findings suggest that safety professionals, risk managers and employers could use aggregated worker perceptions of slipperiness to identify slipping hazards and, potentially, to assess intervention effectiveness. PMID:22935953

  1. New constraints on slip rates of the Fodongmiao-Hongyazi fault in the Northern Qilian Shan, NE Tibet, from the 10Be exposure dating of offset terraces

    Science.gov (United States)

    Yang, Haibo; Yang, Xiaoping; Huang, Xiongnan; Li, An; Huang, Weiliang; Zhang, Ling

    2018-01-01

    The Fodongmo-Hongyazi fault (FHF) is a major thrust of Northeastern Tibet, bounding the Qilian Shan. It accommodates crustal shortening across this region and has produced a strong historical earthquake. Until now the slip rate has been poorly constrained, limiting our understanding of its role in the accommodation of deformation across this region. In this paper, faulted terraces at two sites on the western and middle segments of the FHF were mapped with satellite imagery and field observations. Chronological constraints are placed on the ages of displaced river terraces at these sites using terrestrial cosmogenic nuclide (TCN) exposure dating. These ages combined with offsets measured from SPOT 6 DEM's yield average vertical slip rates of 1.3 ± 0.1 mm/yr for the western segment since ∼207 ka and 0.9 ± 0.1 mm/yr since ∼46 ka for the middle segment. These data suggest that the FHF accommodates ∼15-20% of the total shortening across the Qilian Shan (5.5-7 mm/yr). In addition, comparisons of our data with published slip rates along the Northern Qilian Thrust Fault Zone show that the fastest tectonic uplift occurs along the western portion of the Northern Qilian Shan. This is consistent with estimates deduced from geomorphology. The western portion of the Qilian Shan is mainly controlled by compressional deformation produced by the northward movement of the Northeastern Tibetan Plateau, while the eastern Qilian Shan is mainly controlled by the eastward extrusion of material along the left-lateral Haiyuan strike-slip Fault.

  2. Soil slips and debris flows on terraced slopes

    Science.gov (United States)

    Crosta, G. B.; Dal Negro, P.; Frattini, P.

    Terraces cover large areas along the flanks of many alpine and prealpine valleys. Soil slips and soil slips-debris flows are recurrent phenomena along terraced slopes. These landslides cause damages to people, settlements and cultivations. This study investigates the processes related to the triggering of soil slip-debris flows in these settings, analysing those occurred in Valtellina (Central Alps, Italy) on November 2000 after heavy prolonged rainfalls. 260 landslides have been recognised, mostly along the northern valley flank. About 200 soil slips and slumps occurred in terraced areas and a third of them evolved into debris flows. Field work allowed to recognise the settings at soil slip-debris flow source areas. Landslides affected up to 2.5 m of glacial, fluvioglacial and anthropically reworked deposits overlying metamorphic basement. Laboratory and in situ tests allowed to characterise the geotechnical and hydraulic properties of the terrains involved in the initial failure. Several stratigraphic and hydrogeologic factors have been individuated as significant in determining instabilities on terraced slopes. They are the vertical changes of physical soil properties, the presence of buried hollows where groundwater convergence occurs, the rising up of perched groundwater tables, the overflow and lateral infiltration from superficial drainage network, the runoff concentration by means of pathways and the insufficient drainage of retaining walls.

  3. Experiments on vibration-driven stick-slip locomotion: A sliding bifurcation perspective

    Science.gov (United States)

    Du, Zhouwei; Fang, Hongbin; Zhan, Xiong; Xu, Jian

    2018-05-01

    Dry friction appears at the contact interface between two surfaces and is the source of stick-slip vibrations. Instead of being a negative factor, dry friction is essential for vibration-driven locomotion system to take effect. However, the dry-friction-induced stick-slip locomotion has not been fully understood in previous research, especially in terms of experiments. In this paper, we experimentally study the stick-slip dynamics of a vibration-driven locomotion system from a sliding bifurcation perspective. To this end, we first design and build a vibration-driven locomotion prototype based on an internal piezoelectric cantilever. By utilizing the mechanical resonance, the small piezoelectric deformation is significantly amplified to drive the prototype to achieve effective locomotion. Through identifying the stick-slip characteristics in velocity histories, we could categorize the system's locomotion into four types and obtain a stick-slip categorization diagram. In each zone of the diagram the locomotion exhibits qualitatively different stick-slip dynamics. Such categorization diagram is actually a sliding bifurcation diagram; crossing from one stick-slip zone to another corresponds to the triggering of a sliding bifurcation. In addition, a simplified single degree-of-freedom model is established, with the rationality of simplification been explained theoretically and numerically. Based on the equivalent model, a numerical stick-slip categorization is also obtained, which shows good agreement with the experiments both qualitatively and quantitatively. To the best of our knowledge, this is the first work that experimentally generates a sliding bifurcation diagram. The obtained stick-slip categorizations deepen our understanding of stick-slip dynamics in vibration-driven systems and could serve as a base for system design and optimization.

  4. Overview of the Kinematics of the Salton Trough and Northern Gulf of California

    Science.gov (United States)

    Stock, J. M.

    2016-12-01

    In the Salton Trough and Northern Gulf of California, transtensional rifting is leading to full continental plate breakup, as a major continental block is being transferred to an oceanic plate. Since at least 6 Ma this region has taken up most of the plate boundary slip between the Pacific and North America plates at this latitude. We review the structural history of plate separation, as constrained by many recent studies of present and past fault configurations, seismicity, and basin development as seen from geology and geophysics. Modern activity in the USA is dominated by NW-striking strike-slip faults (San Andreas, San Jacinto, Elsinore), and subsidiary NE-striking faults. There is an equally broad zone in Mexico (faults from the Mexicali Valley to the Colorado River Delta and bounding the Laguna Salada basin), including active low-angle detachment faults. In both areas, shifts in fault activity are indicated by buried faults and exhumed or buried earlier basin strata. Seismicity defines 3 basin segments in the N Gulf: Consag-Wagner, Upper Delfin, and Lower Delfin, but localization is incomplete. These basins occupy a broad zone of modern deformation, lacking single transform faults, although major strike-slip faults formed in the surrounding continental area. The off-boundary deformation on the western side of the plate boundary has changed with time, as seen by Holocene and Quaternary faults controlling modern basins in the Gulf Extensional Province of NE Baja California, and stranded Pliocene continental and marine basin strata in subaerial fault blocks. The eastern side of the plate boundary, in the shallow northeastern Gulf, contains major NW-striking faults that may have dominated the earlier (latest Miocene-early Pliocene) kinematics. The Sonoran coastal plain likely buries additional older faults and basin sequences; further studies here are needed to refine models of the earlier structural development of this sector. Despite > 250 km of plate

  5. An Improved Optimal Slip Ratio Prediction considering Tyre Inflation Pressure Changes

    Directory of Open Access Journals (Sweden)

    Guoxing Li

    2015-01-01

    Full Text Available The prediction of optimal slip ratio is crucial to vehicle control systems. Many studies have verified there is a definitive impact of tyre pressure change on the optimal slip ratio. However, the existing method of optimal slip ratio prediction has not taken into account the influence of tyre pressure changes. By introducing a second-order factor, an improved optimal slip ratio prediction considering tyre inflation pressure is proposed in this paper. In order to verify and evaluate the performance of the improved prediction, a cosimulation platform is developed by using MATLAB/Simulink and CarSim software packages, achieving a comprehensive simulation study of vehicle braking performance cooperated with an ABS controller. The simulation results show that the braking distances and braking time under different tyre pressures and initial braking speeds are effectively shortened with the improved prediction of optimal slip ratio. When the tyre pressure is slightly lower than the nominal pressure, the difference of braking performances between original optimal slip ratio and improved optimal slip ratio is the most obvious.

  6. Significado tectónico y migración de fluidos hidrotermales en una red de fallas y vetas de un Dúplex de rumbo: un ejemplo del Sistema de Falla de Atacama Tectonic significance and hydrothermal fluid migration within a strike-slip duplex fault-vein network: an example from the Atacama Fault System

    Directory of Open Access Journals (Sweden)

    Viviana Olivares

    2010-07-01

    Full Text Available El Dúplex Caleta Coloso es una estructura de rumbo desarrollada durante la deformación frágil del Sistema de Falla de Atacama (SFA en el Cretácico Temprano. En su interior hay un sistema de vetas hidrotermales que documentan la naturaleza de la relación entre el transporte de fluidos y el desarrollo del dúplex. El sistema de vetas de orientación dominante NW se localiza en la roca de caja, adyacentes a las zonas de falla. Según su mineralogía dominante hay vetas de clorita, epidota-cuarzo y calcita-limonita, y según las relaciones de corte o su estructura interna, se definieron vetas tempranas (clorita, intermedias (epidota-cuarzo y tardías (calcita-limonitas. Algunas vetas muestran cristales perpendiculares u oblicuos a sus paredes (vetas de extensión y de extensión oblicua o fibras minerales orientadas paralelas a las estrías de las fallas (vetas-fallas. Estas últimas tienen indicadores cinemáticos compatibles con las fallas, evidenciando que fueron sincinemáticas con el desarrollo del dúplex. Según su microestructura, ellas se habrían formado en fracturas abiertas llenas de fluidos, bajo condiciones de presión inferior a la hidrostática, lo cual indicaría que la precipitación mineral ocurrió por caídas abruptas de la presión en una corteza somera (The Caleta Coloso Duplex is a brittle strike-slip structure developed along the Atacama Fault System during the Early Cretaceous. A hydrothermal vein system existing within the duplex documents the nature of the link between fluid transport and progressive structural development. The dominantly NW-striking vein system occurs near or at the damage zone of the duplex fault zones. Veins can be classified according to their composition and crosscutting relationships into early chlorite veins, intermediate epidotic-quartz veins and late calcite-limonite veins. Some of them exhibit minerals with their long axes oriented orthogonally or obliquely with respect to the vein walls

  7. Hydrodynamic slip length as a surface property

    Science.gov (United States)

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.

    2016-02-01

    Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems.

  8. Mesozoic strike-slip movement of the Dunhua-Mishan Fault Zone in NE China: A response to oceanic plate subduction

    Science.gov (United States)

    Liu, Cheng; Zhu, Guang; Zhang, Shuai; Gu, Chengchuan; Li, Yunjian; Su, Nan; Xiao, Shiye

    2018-01-01

    The NE-striking Dunhua-Mishan Fault Zone (DMFZ) is one of two branches of the continental-scale sinistral Tan-Lu Fault Zone in NE China. The field data presented here indicate that the ca. 1000 km long DMFZ records two phases of sinistral faulting. The structures produced by these two phases of faulting include NE-SW-striking ductile shear belts and brittle faults, respectively. Mylonite-hosted microstructures and quartz c-axis fabrics suggest deformation temperatures of 450 °C-500 °C for the ductile shear belts. Combining new zircon U-Pb dates for 14 igneous rock samples analyzed during this study with the geology of this region indicates these shear belts formed during the earliest Early Cretaceous. This phase of sinistral displacement represents the initial formation of the DMFZ in response to the northward propagation of the Tan-Lu Fault Zone into NE China. A phase of Early Cretaceous rifting was followed by a second phase of sinistral faulting at 102-96 Ma, as evidenced by our new U-Pb ages for associated igneous rocks. Combining our new data with the results of previous research indicates that the DFMZ records a four-stage Cretaceous evolutionary history, where initial sinistral faulting at the beginning of the Early Cretaceous gave way to rifting during the rest of the Early Cretaceous. This was followed by a second phase of sinistral faulting at the beginning of the Late Cretaceous and a second phase of local rifting during the rest of the Late Cretaceous. The Cretaceous evolution of the DMFZ records the synchronous tectonic evolution of the NE China continent bordering the Pacific Ocean. Two phases of regional N-S compression generated the two phases of sinistral faulting within the DMFZ, whereas two-stage regional extension generated the two phases of rifting. The two compressive events were the result of the rapid low-angle subduction of the Izanagi and Pacific plates, whereas the two-stage extension was caused by the roll-back of these respective

  9. Wavelet transform analysis of electromyography kung fu strikes data.

    Science.gov (United States)

    Neto, Osmar Pinto; Marzullo, Ana Carolina de Miranda

    2009-11-01

    In martial arts and contact sports strikes are performed at near maximum speeds. For that reason, electromyography (EMG) analysis of such movements is non-trivial. This paper has three main goals: firstly, to investigate the differences in the EMG activity of muscles during strikes performed with and without impacts; secondly, to assess the advantages of using Sum of Significant Power (SSP) values instead of root mean square (rms) values when analyzing EMG data; and lastly to introduce a new method of calculating median frequency values using wavelet transforms (WMDF). EMG data of the deltoid anterior (DA), triceps brachii (TB) and brachioradialis (BR) muscles were collected from eight Kung Fu practitioners during strikes performed with and without impacts. SSP results indicated significant higher muscle activity (p = 0.023) for the strikes with impact. WMDF results, on the other hand, indicated significant lower values (p = 0. 007) for the strikes with impact. SSP results presented higher sensitivity than rms to quantify important signal differences and, at the same time, presented lower inter-subject coefficient of variations. The result of increase in SSP values and decrease in WMDF may suggest better synchronization of motor units for the strikes with impact performed by the experienced Kung Fu practitioners. Key PointsThe results show higher muscle activity and lower electromyography median frequencies for strikes with impact compared to strikes without.SSP results presented higher sensitivity and lower inter-subject coefficient of variations than rms results.Kung Fu palm strikes with impact may present better motor units' synchronization than strikes without.

  10. Perceived risks for slipping and falling at work during wintertime and criteria for a slip-resistant winter shoe among Swedish outdoor workers

    OpenAIRE

    Norlander, Anna; Miller, Michael; Gard, Gunvor

    2015-01-01

    The leading cause of work related accidents in Sweden is falls. Many slips and falls occur on icy and snowy surfaces, but there is limited knowledge about how to prevent accidents during outdoor work in winter conditions. The purpose of this study was to describe risk factors of slips and falls and criteria for slip-resistant winter shoes from a user perspective. The result is based on focus group interviews with 20 men and women working in mail delivery, construction and home care in Sweden....

  11. Prediction of fluid velocity slip at solid surfaces

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Todd, Billy; Daivis, Peter

    2011-01-01

    methods, it allows us to directly compute the intrinsic wall-fluid friction coefficient rather than an empirical friction coefficient that includes all sources of friction for planar shear flow. The slip length predicted by our method is in excellent agreement with the slip length obtained from direct...

  12. Wheel slip dump valve for railway braking system

    Science.gov (United States)

    Zhang, Xuan; Zhang, LiHao; Li, QingXuan; Shi, YanTao

    2017-09-01

    As we all know, pneumatic braking system plays an important role in the safety of the whole vehicle. In the anti slip braking system, the pressure of braking cylinder can be adjusted by the quick power response of wheel slip dump valve, so that the lock situation won’t occur during vehicle service. During the braking of railway vehicles, the braking force provided by braking disc reduces vehicle’s speed. But the locking slip will happen due to the oversize of braking force or the reduction of sticking coefficient between wheel and rail. It will cause not only the decline of braking performance but also the increase of braking distance. In the meanwhile, it will scratch the wheel and influence the stable running of vehicles. Now, the speed of passenger vehicle has been increased. In order to shorten the braking distance as far as possible, sticking stickiness must be fully applied. So the occurrence probability of wheel slip is increased.

  13. When Push Comes to Shove: Strikes in Higher Education.

    Science.gov (United States)

    Magney, John

    2002-01-01

    To provide a better sense of how academic unions handle a strike situation, examines six unions who, between 1996 and 2000, went through strikes. Discusses the key issues and outcomes of the strikes. (EV)

  14. Velocity-dependent quantum phase slips in 1D atomic superfluids.

    Science.gov (United States)

    Tanzi, Luca; Scaffidi Abbate, Simona; Cataldini, Federica; Gori, Lorenzo; Lucioni, Eleonora; Inguscio, Massimo; Modugno, Giovanni; D'Errico, Chiara

    2016-05-18

    Quantum phase slips are the primary excitations in one-dimensional superfluids and superconductors at low temperatures but their existence in ultracold quantum gases has not been demonstrated yet. We now study experimentally the nucleation rate of phase slips in one-dimensional superfluids realized with ultracold quantum gases, flowing along a periodic potential. We observe a crossover between a regime of temperature-dependent dissipation at small velocity and interaction and a second regime of velocity-dependent dissipation at larger velocity and interaction. This behavior is consistent with the predicted crossover from thermally-assisted quantum phase slips to purely quantum phase slips.

  15. Lower limb joint angles and ground reaction forces in forefoot strike and rearfoot strike runners during overground downhill and uphill running.

    Science.gov (United States)

    Kowalski, Erik; Li, Jing Xian

    2016-11-01

    This study investigated the normal and parallel ground reaction forces during downhill and uphill running in habitual forefoot strike and habitual rearfoot strike (RFS) runners. Fifteen habitual forefoot strike and 15 habitual RFS recreational male runners ran at 3 m/s ± 5% during level, uphill and downhill overground running on a ramp mounted at 6° and 9°. Results showed that forefoot strike runners had no visible impact peak in all running conditions, while the impact peaks only decreased during the uphill conditions in RFS runners. Active peaks decreased during the downhill conditions in forefoot strike runners while active loading rates increased during downhill conditions in RFS runners. Compared to the level condition, parallel braking peaks were larger during downhill conditions and parallel propulsive peaks were larger during uphill conditions. Combined with previous biomechanics studies, our findings suggest that forefoot strike running may be an effective strategy to reduce impacts, especially during downhill running. These findings may have further implications towards injury management and prevention.

  16. Relating stick-slip friction experiments to earthquake source parameters

    Science.gov (United States)

    McGarr, Arthur F.

    2012-01-01

    Analytical results for parameters, such as static stress drop, for stick-slip friction experiments, with arbitrary input parameters, can be determined by solving an energy-balance equation. These results can then be related to a given earthquake based on its seismic moment and the maximum slip within its rupture zone, assuming that the rupture process entails the same physics as stick-slip friction. This analysis yields overshoots and ratios of apparent stress to static stress drop of about 0.25. The inferred earthquake source parameters static stress drop, apparent stress, slip rate, and radiated energy are robust inasmuch as they are largely independent of the experimental parameters used in their estimation. Instead, these earthquake parameters depend on C, the ratio of maximum slip to the cube root of the seismic moment. C is controlled by the normal stress applied to the rupture plane and the difference between the static and dynamic coefficients of friction. Estimating yield stress and seismic efficiency using the same procedure is only possible when the actual static and dynamic coefficients of friction are known within the earthquake rupture zone.

  17. Factors associated with use of slip-resistant shoes in US limited-service restaurant workers.

    Science.gov (United States)

    Verma, Santosh K; Courtney, Theodore K; Corns, Helen L; Huang, Yueng-Hsiang; Lombardi, David A; Chang, Wen-Ruey; Brennan, Melanye J; Perry, Melissa J

    2012-06-01

    Slips and falls are a leading cause of injury at work. Several studies have indicated that slip-resistant shoes can reduce the risk of occupational slips and falls. Few studies, however, have examined the determinants of slip-resistant shoe use. This study examined the individual and workplace factors associated with slip-resistant shoe use. 475 workers from 36 limited-service restaurants in the USA participated in a study of workplace slipping. Demographic and job characteristic information about each participant was collected. Restaurant managers provided information on whether slip-resistant shoes were provided and paid for by the employer and whether any guidance was given regarding slip-resistant shoe use when they were not provided. Kitchen floor coefficient of friction was measured. Slip-resistant status of the shoes was determined by noting the presence of a 'slip-resistant' marking on the sole. Poisson regression with robust SE was used to calculate prevalence ratios. 320 participants wore slip-resistant shoes (67%). In the multivariate analysis, the prevalence of slip-resistant shoe use was lowest in 15-19-year age group. Women were more likely to wear slip-resistant shoes (prevalence ratio 1.18, 95% CI 1.07 to 1.31). The prevalence of slip-resistant shoe use was lower when no guidance regarding slip-resistant shoes was given as compared to when they were provided by the employer (prevalence ratio 0.66, 95% CI 0.55 to 0.79). Education level, job tenure and the mean coefficient of friction had no significant effects on the use of slip-resistant shoes. Provision of slip-resistant shoes was the strongest predictor of their use. Given their effectiveness and low cost, employers should consider providing slip-resistant shoes at work.

  18. Geology of the continental margin beneath Santa Monica Bay, Southern California, from seismic-reflection data

    Science.gov (United States)

    Fisher, M.A.; Normark, W.R.; Bohannon, R.G.; Sliter, R.W.; Calvert, A.J.

    2003-01-01

    We interpret seismic-reflection data, which were collected in Santa Monica Bay using a 70-in3 generator-injector air gun, to show the geologic structure of the continental shelf and slope and of the deep-water, Santa Monica and San Pedro Basins. The goal of this research is to investigate the earthquake hazard posed to urban areas by offshore faults. These data reveal that northwest of the Palos Verdes Peninsula, the Palos Verdes Fault neither offsets the seafloor nor cuts through an undeformed sediment apron that postdates the last sea level rise. Other evidence indicates that this fault extends northwest beneath the shelf in the deep subsurface. However, other major faults in the study area, such as the Dume and San Pedro Basin Faults, were active recently, as indicated by an arched seafloor and offset shallow sediment. Rocks under the lower continental slope are deformed to differing degrees on opposite sides of Santa Monica Canyon. Northwest of this canyon, the continental slope is underlain by a little-deformed sediment apron; the main structures that deform this apron are two lower-slope anticlines that extend toward Point Dume and are cored by faults showing reverse or thrust separation. Southeast of Santa Monica Canyon, lower-slope rocks are deformed by a complex arrangement of strike-slip, normal, and reverse faults. The San Pedro Escarpment rises abruptly along the southeast side of Santa Monica Canyon. Reverse faults and folds underpinning this escarpment steepen progressively southeastward. Locally they form flower structures and cut downward into basement rocks. These faults merge downward with the San Pedro Basin fault zone, which is nearly vertical and strike slip. The escarpment and its attendant structures diverge from this strike-slip fault zone and extend for 60 km along the margin, separating the continental shelf from the deep-water basins. The deep-water Santa Monica Basin has large extent but is filled with only a thin (less than 1.5-km

  19. Patellofemoral joint stress during running with alterations in foot strike pattern.

    Science.gov (United States)

    Vannatta, Charles Nathan; Kernozek, Thomas W

    2015-05-01

    This study aimed to quantify differences in patellofemoral joint stress that may occur when healthy runners alter their foot strike pattern from their habitual rearfoot strike to a forefoot strike to gain insight on the potential etiology and treatment methods of patellofemoral pain. Sixteen healthy female runners completed 20 running trials in a controlled laboratory setting under rearfoot strike and forefoot strike conditions. Kinetic and kinematic data were used to drive a static optimization technique to estimate individual muscle forces to input into a model of the patellofemoral joint to estimate joint stress during running. Peak patellofemoral joint stress and the stress-time integral over stance phase decreased by 27% and 12%, respectively, in the forefoot strike condition (P forefoot strike condition (P forefoot strike (P forefoot strike condition (P strike pattern to a forefoot strike results in consistent reductions in patellofemoral joint stress independent of changes in step length. Thus, implementation of forefoot strike training programs may be warranted in the treatment of runners with patellofemoral pain. However, it is suggested that the transition to a forefoot strike pattern should be completed in a graduated manner.

  20. Martial arts striking hand peak acceleration, accuracy and consistency.

    Science.gov (United States)

    Neto, Osmar Pinto; Marzullo, Ana Carolina De Miranda; Bolander, Richard P; Bir, Cynthia A

    2013-01-01

    The goal of this paper was to investigate the possible trade-off between peak hand acceleration and accuracy and consistency of hand strikes performed by martial artists of different training experiences. Ten male martial artists with training experience ranging from one to nine years volunteered to participate in the experiment. Each participant performed 12 maximum effort goal-directed strikes. Hand acceleration during the strikes was obtained using a tri-axial accelerometer block. A pressure sensor matrix was used to determine the accuracy and consistency of the strikes. Accuracy was estimated by the radial distance between the centroid of each subject's 12 strikes and the target, whereas consistency was estimated by the square root of the 12 strikes mean squared distance from their centroid. We found that training experience was significantly correlated to hand peak acceleration prior to impact (r(2)=0.456, p =0.032) and accuracy (r(2)=0. 621, p=0.012). These correlations suggest that more experienced participants exhibited higher hand peak accelerations and at the same time were more accurate. Training experience, however, was not correlated to consistency (r(2)=0.085, p=0.413). Overall, our results suggest that martial arts training may lead practitioners to achieve higher striking hand accelerations with better accuracy and no change in striking consistency.

  1. Orthotic intervention in forefoot and rearfoot strike running patterns.

    Science.gov (United States)

    Stackhouse, Carrie Laughton; Davis, Irene McClay; Hamill, Joseph

    2004-01-01

    To compare the differential effect of custom orthoses on the lower extremity mechanics of a forefoot and rearfoot strike pattern. Fifteen subjects ran with both a forefoot and a rearfoot strike pattern with and without orthoses. Lower extremity kinematic and kinetic variables were compared between strike pattern and orthotic conditions. Foot orthoses have been shown to be effective in controlling excessive rearfoot motion in rearfoot strikers. The effect of orthotic intervention on rearfoot motion in forefoot strikers has not been previously reported. Five trials were collected for each condition. Peak rearfoot eversion, eversion excursion, eversion velocity, peak inversion moment, and inversion work were compared between conditions. Kinematic variables in the sagittal plane of the rearfoot and in the frontal and sagittal plane of the knee were also determined. Increased rearfoot excursions and velocities and decreased peak eversion were noted in the forefoot strike pattern compared to the rearfoot strike pattern. Orthotic intervention, however,did not significantly change rearfoot motion in either strike pattern. Reductions in internal rotation and abduction of the knee were noted with orthotic intervention. Foot orthoses do not differentially effect rearfoot motion of a rearfoot strike and a forefoot strike running pattern. Orthotic intervention has a larger and more systematic effect on rearfoot kinetics compared to rearfoot kinematics.

  2. Source model for the 1997 Zirkuh earthquake (MW= 7.2) in Iran derived from JERS and ERS InSAR observations

    KAUST Repository

    Sudhaus, Henriette

    2011-05-01

    We present the first detailed source model of the 1997 M7.2 Zirkuh earthquake that ruptured the entire Abiz fault in East Iran producing a 125 km long, bended and segmented fault trace. Using SAR data from the ERS and JERS-1 satellites we first determined a multisegment fault model for this predominately strike-slip earthquake by estimating fault-segment dip, slip, and rake values using an evolutionary optimization algorithm. We then inverted the InSAR data for variable slip and rake in more detail along the multisegment fault plane. We complement our optimization with importance sampling of the model parameter space to ensure that the derived optimum model has a high likelihood, to detect correlations or trade-offs between model parameters, and to image the model resolution. Our results are in an agreement with field observations showing that this predominantly strike-slip earthquake had a clear change in style of faulting along its rupture. In the north we find that thrust faulting on a westerly dipping fault is accompanied with the strike-slip that changes to thrust faulting on an eastward dipping fault plane in the south. The centre part of the fault is vertical and has almost pure dextral strike-slip. The heterogeneous fault slip distribution shows two regions of low slip near significant fault step-overs of the Abiz fault and therefore these fault complexities appear to reduce the fault slip. Furthermore, shallow fault slip is generally reduced with respect to slip at depth. This shallow slip deficit varies along the Zirkuh fault from a small deficit in the North to a much larger deficit along the central part of the fault, a variation that is possibly related to different interseismic repose times.

  3. Assessment of slip factor models at off-design condition

    International Nuclear Information System (INIS)

    Yoon, Sung Ho; Baek, Je Hyun

    2000-01-01

    Slip factor is defined as an empirical factor being multiplied to theoretical energy transfer for the estimation of real work input of a centrifugal compressor. Researchers have tried to develop a simple empirical model, for a century, to predict a slip factor. However most these models were developed on the condition of design point assuming inviscid flow. So these models often fail to predict a correct slip factor at off-design condition. In this study, we summarized various slip factor models and compared these models with experimental and numerical data at off-design condition. As a result of this study, Wiesner's and Paeng and Chung's models are applicable for radial impeller, but all the models are not suitable for backswept impeller. Finally, the essential avenues for future study is discussed

  4. VARIATION OF STRIKE INCENTIVES IN DEEP REDUCTIONS; FINAL

    International Nuclear Information System (INIS)

    G.H. CANAVAN

    2001-01-01

    This note studies the sensitivity of strike incentives to deep offensive force reductions using exchange, cost, and game theoretic decision models derived and discussed in companion reports. As forces fall, weapon allocations shift from military to high value targets, with the shift being half complete at about 1,000 weapons. By 500 weapons, the first and second strikes are almost totally on high value. The dominant cost for striking first is that of damage to one's high value, which is near total absent other constraints, and hence proportional to preferences for survival of high value. Changes in military costs are largely offsetting, so total first strike costs change little. The resulting costs at decision nodes are well above the costs of inaction, so the preferred course is inaction for all offensive reductions studied. As the dominant cost for striking first is proportional to the preference for survival of high value. There is a wide gap between the first strike cost and that of inaction for the parameters studied here. These conclusions should be insensitive to significant reductions in the preference for survival of high value, which is the most sensitive parameter

  5. Listening in on Friction: Stick-Slip Acoustical Signatures in Velcro

    Science.gov (United States)

    Hurtado Parra, Sebastian; Morrow, Leslie; Radziwanowski, Miles; Angiolillo, Paul

    2013-03-01

    The onset of kinetic friction and the possible resulting stick-slip motion remain mysterious phenomena. Moreover, stick-slip dynamics are typically accompanied by acoustic bursts that occur temporally with the slip event. The dry sliding dynamics of the hook-and-loop system, as exemplified by Velcro, manifest stick-slip behavior along with audible bursts that are easily micrphonically collected. Synchronized measurements of the friction force and acoustic emissions were collected as hooked Velcro was driven at constant velocity over a bed of looped Velcro in an anechoic chamber. Not surprising, the envelope of the acoustic bursts maps well onto the slip events of the friction force time series and the intensity of the bursts trends with the magnitude of the difference of the friction force during a stick-slip event. However, the analysis of the acoustic emission can serve as a sensitive tool for revealing some of the hidden details of the evolution of the transition from static to kinetic friction. For instance, small acoustic bursts are seen prior to the Amontons-Coulomb threshold, signaling precursor events prior to the onset of macroscopically observed motion. Preliminary spectral analysis of the acoustic emissions including intensity-frequency data will be presented.

  6. Dislocation cross-slip in fcc solid solution alloys

    International Nuclear Information System (INIS)

    Nöhring, Wolfram Georg; Curtin, W.A.

    2017-01-01

    Cross-slip is a fundamental process of screw dislocation motion and plays an important role in the evolution of work hardening and dislocation structuring in metals. Cross-slip has been widely studied in pure FCC metals but rarely in FCC solid solutions. Here, the cross-slip transition path in solid solutions is calculated using atomistic methods for three representative systems of Ni-Al, Cu-Ni and Al-Mg over a range of solute concentrations. Studies using both true random alloys and their corresponding average-alloy counterparts allow for the independent assessment of the roles of (i) fluctuations in the spatial solute distribution in the true random alloy randomness and (ii) average alloy properties such as stacking fault energy. The results show that the solute fluctuations dominate the activation energy barrier, i.e. there are large sample-to-sample variations around the average activation barrier. The variations in activation barrier correlate linearly with the energy difference between the initial and final states. The distribution of this energy difference can be computed analytically in terms of the solute/dislocation interaction energies. Thus, the distribution of cross-slip activation energies can be accurately determined from a parameter-free analytic model. The implications of the statistical distribution of activation energies on the rate of cross-slip in real alloys are then identified.

  7. Existence of Stick-Slip Periodic Solutions in a Dry Friction Oscillator

    International Nuclear Information System (INIS)

    Li Qun-Hong; Chen Yu-Ming; Qin Zhi-Ying

    2011-01-01

    The stick-slip behavior in friction oscillators is very complicated due to the non-smoothness of the dry friction, which is the basic form of motion of dynamical systems with friction. In this paper, the stick-slip periodic solution in a single-degree-of-freedom oscillator with dry friction is investigated in detail. Under the assumption of kinetic friction being the Coulomb friction, the existence of the stick-slip periodic solution is considered to give out an analytic criterion in a class of friction systems. A two-parameter unfolding diagram is also described. Moreover, the time and states of motion on the boundary of the stick and slip motions are semi-analytically obtained in a single stick-slip period. (general)

  8. Estimation of vertical slip rate in an active fault-propagation fold from the analysis of a progressive unconformity at the NE segment of the Carrascoy Fault (SE Iberia)

    Science.gov (United States)

    Martin-Banda, Raquel; Insua-Arevalo, Juan Miguel; Garcia-Mayordomo, Julian

    2017-04-01

    Many studies have dealt with the calculation of fault-propagation fold growth rates considering a variety of kinematics models, from limb rotation to hinge migration models. In most cases, the different geometrical and numeric growth models are based on horizontal pre-growth strata architecture and a constant known slip rate. Here, we present the estimation of the vertical slip rate of the NE Segment of the Carrascoy Fault (SE Iberian Peninsula) from the geometrical modeling of a progressive unconformity developed on alluvial fan sediments with a high depositional slope. The NE Segment of the Carrascoy Fault is a left-lateral strike slip fault with reverse component belonging to the Eastern Betic Shear Zone, a major structure that accommodates most of the convergence between Iberian and Nubian tectonics plates in Southern Spain. The proximity of this major fault to the city of Murcia encourages the importance of carrying out paleosismological studies in order to determinate the Quaternary slip rate of the fault, a key geological parameter for seismic hazard calculations. This segment is formed by a narrow fault zone that articulates abruptly the northern edge of the Carrascoy Range with the Guadalentin Depression through high slope, short alluvial fans Upper-Middle Pleistocene in age. An outcrop in a quarry at the foot of this front reveals a progressive unconformity developed on these alluvial fan deposits, showing the important reverse component of the fault. The architecture of this unconformity is marked by well-developed calcretes on the top some of the alluvial deposits. We have determined the age of several of these calcretes by the Uranium-series disequilibrium dating method. The results obtained are consistent with recent published studies on the SW segment of the Carrascoy Fault that together with offset canals observed at a few locations suggest a net slip rate close to 1 m/ka.

  9. Dynamic Behavior of Fault Slip Induced by Stress Waves

    Directory of Open Access Journals (Sweden)

    Guang-an Zhu

    2016-01-01

    Full Text Available Fault slip burst is a serious dynamic hazard in coal mining. A static and dynamic analysis for fault slip was performed to assess the risk of rock burst. A numerical model FLAC3D was established to understand the stress state and mechanical responses of fault rock system. The results obtained from the analysis show that the dynamic behavior of fault slip induced by stress waves is significantly affected by mining depth, as well as dynamic disturbance intensity and the distance between the stope and the fault. The isolation effect of the fault is also discussed based on the numerical results with the fault angle appearing to have the strongest influence on peak vertical stress and velocity induced by dynamic disturbance. By taking these risks into account, a stress-relief technology using break-tip blast was used for fault slip burst control. This technique is able to reduce the stress concentration and increase the attenuation of dynamic load by fracturing the structure of coal and rock. The adoption of this stress-relief method leads to an effective reduction of fault slip induced rock burst (FSIRB occurrence.

  10. Using regional moment tensors to constrain the kinematics and stress evolution of the 2010–2013 Canterbury earthquake sequence, South Island, New Zealand

    Science.gov (United States)

    Herman, Matthew W.; Herrmann, Robert B.; Benz, Harley M.; Furlong, Kevin P.

    2014-01-01

    On September 3, 2010, a MW 7.0 (U.S. Geological Survey moment magnitude) earthquake ruptured across the Canterbury Plains in South Island, New Zealand. Since then, New Zealand GNS Science has recorded over 10,000 aftershocks ML 2.0 and larger, including three destructive ~ MW 6.0 earthquakes near Christchurch. We treat the Canterbury earthquake sequence as an intraplate earthquake sequence, and compare its kinematics to an Andersonian model for fault slip in a uniform stress field. We determined moment magnitudes and double couple solutions for 150 earthquakes having MW 3.7 and larger through the use of a waveform inversion technique using data from broadband seismic stations on South Island, New Zealand. The majority (126) of these double couple solutions have strike-slip focal mechanisms, with right-lateral slip on ENE fault planes or equivalently left-lateral slip on SSE fault planes. The remaining focal mechanisms indicate reverse faulting, except for two normal faulting events. The strike-slip segments have compatible orientations for slip in a stress field with a horizontal σ1 oriented ~ N115°E, and horizontal σ3. The preference for right lateral strike-slip earthquakes suggests that these structures are inherited from previous stages of deformation. Reverse slip is interpreted to have occurred on previously existing structures in regions with an absence of existing structures optimally oriented for strike-slip deformation. Despite the variations in slip direction and faulting style, most aftershocks had nearly the same P-axis orientation, consistent with the regional σ1. There is no evidence for significant changes in these stress orientations throughout the Canterbury earthquake sequence.

  11. Pan-African deformations in the basement of the Negele area, southern Ethiopia

    Science.gov (United States)

    Yihunie, Tadesse

    2002-03-01

    Polydeformed and metamorphosed Neoproterozoic rocks of the East African Orogen in the Negele area constituted three lithostructurally distinct and thrust-bounded terranes. These are, from west to east, the Kenticha, Alghe and Bulbul terranes. The Kenticha and Bulbul terranes are metavolcano-sedimentary and ultramafic sequences, representing parts of the Arabian-Nubian Shield (ANS), which are welded to the central Alghe gneissic terrane of the Mozambique Belt affinity along N-S-trending sheared thrust contacts. Structural data suggest that the Negele basement had evolved through three phases of deformation. During D1 (folding) deformation, north-south upright and inclined folds with north-trending axes were developed. East and west-verging thrusts, right-lateral shearing along the north-oriented Kenticha and Bulbul thrust contacts and related structural elements were developed during D2 (thrusting) deformation. The pervasive D1 event is interpreted to have occurred at 620-610 Ma and the D2 event ended prior to 554 Ma. Right-lateral strike-slips along thrust contacts are interpreted to have been initiated during late D2. During D3, left-lateral strike-slip along the Wadera Shear Zone and respective strike-slip movements along conjugate set of shear zones were developed in the Alghe terrane, and are interpreted to have occurred later than 557 Ma. The structural data suggest that eastward thrusting of the Kenticha and westward tectonic transport of the Bulbul sequences over the Alghe gneissic terrane of the Mozambique Belt, during D2, were accompanied by right-lateral strike-slip displacements along thrust contacts. Right-lateral strike-slip movements along the Kenticha thrust contact, further suggest northward movement of the Kenticha sequence during the Pan-African orogeny in the Neoproterozoic. Left-lateral strike-slip along the orogen-parallel NNE-SSW Wadera Shear Zone and strike-slip movements along a conjugate set of shear zones completed final terrane

  12. Drag on a slip spherical particle moving in a couple stress fluid

    Directory of Open Access Journals (Sweden)

    E.A. Ashmawy

    2016-06-01

    Full Text Available The creeping motion of a rigid slip sphere in an unbounded couple stress fluid is investigated. The linear slip boundary condition and the vanishing couple stress condition are applied on the surface of the sphere. A simple formula for the drag force acting on a slip sphere translating in an unbounded couple stress fluid is obtained. Special cases of the deduced drag formula are concluded and compared with analogous results in the literature. The normalized drag force experienced by the fluid on the slip sphere is represented graphically and the effects of slip parameter and viscosity coefficients are discussed.

  13. The phase slip factor of the electrostatic cryogenic storage ring CSR

    Science.gov (United States)

    Grieser, Manfred; von Hahn, Robert; Vogel, Stephen; Wolf, Andreas

    2017-07-01

    To determine the momentum spread of an ion beam from the measured revolution frequency distribution, the knowledge of the phase slip factor of the storage ring is necessary. The slip factor was measured for various working points of the cryogenic storage ring CSR at MPI for Nuclear Physics, Heidelberg and was compared with simulations. The predicted functional relationship of the slip factor and the horizontal tune depends on the different islands of stability, which has been experimentally verified. This behavior of the slip factor is in clear contrast to that of magnetic storage rings.

  14. Joint stiffness and running economy during imposed forefoot strike before and after a long run in rearfoot strike runners.

    Science.gov (United States)

    Melcher, Daniel A; Paquette, Max R; Schilling, Brian K; Bloomer, Richard J

    2017-12-01

    Research has focused on the effects of acute strike pattern modifications on lower extremity joint stiffness and running economy (RE). Strike pattern modifications on running biomechanics have mostly been studied while runners complete short running bouts. This study examined the effects of an imposed forefoot strike (FFS) on RE and ankle and knee joint stiffness before and after a long run in habitual rearfoot strike (RFS) runners. Joint kinetics and RE were collected before and after a long run. Sagittal joint kinetics were computed from kinematic and ground reaction force data that were collected during over-ground running trials in 13 male runners. RE was measured during treadmill running. Knee flexion range of motion, knee extensor moment and ankle joint stiffness were lower while plantarflexor moment and knee joint stiffness were greater during imposed FFS compared with RFS. The long run did not influence the difference in ankle and knee joint stiffness between strike patterns. Runners were more economical during RFS than imposed FFS and RE was not influenced by the long run. These findings suggest that using a FFS pattern towards the end of a long run may not be mechanically or metabolically beneficial for well-trained male RFS runners.

  15. Constraining the kinematics of metropolitan Los Angeles faults with a slip-partitioning model.

    Science.gov (United States)

    Daout, S; Barbot, S; Peltzer, G; Doin, M-P; Liu, Z; Jolivet, R

    2016-11-16

    Due to the limited resolution at depth of geodetic and other geophysical data, the geometry and the loading rate of the ramp-décollement faults below the metropolitan Los Angeles are poorly understood. Here we complement these data by assuming conservation of motion across the Big Bend of the San Andreas Fault. Using a Bayesian approach, we constrain the geometry of the ramp-décollement system from the Mojave block to Los Angeles and propose a partitioning of the convergence with 25.5 ± 0.5 mm/yr and 3.1 ± 0.6 mm/yr of strike-slip motion along the San Andreas Fault and the Whittier Fault, with 2.7 ± 0.9 mm/yr and 2.5 ± 1.0 mm/yr of updip movement along the Sierra Madre and the Puente Hills thrusts. Incorporating conservation of motion in geodetic models of strain accumulation reduces the number of free parameters and constitutes a useful methodology to estimate the tectonic loading and seismic potential of buried fault networks.

  16. Evaluating the Effects of a Bird Strike Advisory System

    NARCIS (Netherlands)

    Metz, I.C.; Mühlhausen, T; Ellerbroek, J.; Hoekstra, J.M.

    2016-01-01

    Bird strikes have operational impacts and cause economic loss to the aviation industry. In the worst case, the damages resulting from bird strikes lead to crashes. The highest risk for bird strikes lies in the area below 3000 ft and thus mainly in airport environments. Despite intense efforts from

  17. Debunking the viper's strike: harmless snakes kill a common assumption.

    Science.gov (United States)

    Penning, David A; Sawvel, Baxter; Moon, Brad R

    2016-03-01

    To survive, organisms must avoid predation and acquire nutrients and energy. Sensory systems must correctly differentiate between potential predators and prey, and elicit behaviours that adjust distances accordingly. For snakes, strikes can serve both purposes. Vipers are thought to have the fastest strikes among snakes. However, strike performance has been measured in very few species, especially non-vipers. We measured defensive strike performance in harmless Texas ratsnakes and two species of vipers, western cottonmouths and western diamond-backed rattlesnakes, using high-speed video recordings. We show that ratsnake strike performance matches or exceeds that of vipers. In contrast with the literature over the past century, vipers do not represent the pinnacle of strike performance in snakes. Both harmless and venomous snakes can strike with very high accelerations that have two key consequences: the accelerations exceed values that can cause loss of consciousness in other animals, such as the accelerations experienced by jet pilots during extreme manoeuvres, and they make the strikes faster than the sensory and motor responses of mammalian prey and predators. Both harmless and venomous snakes can strike faster than the blink of an eye and often reach a target before it can move. © 2016 The Author(s).

  18. Mechanism and energetics of dislocation cross-slip in hcp metals

    Science.gov (United States)

    Wu, Zhaoxuan; Curtin, W. A.

    2016-10-01

    Hexagonal close-packed (hcp) metals such as Mg, Ti, and Zr are lightweight and/or durable metals with critical structural applications in the automotive (Mg), aerospace (Ti), and nuclear (Zr) industries. The hcp structure, however, brings significant complications in the mechanisms of plastic deformation, strengthening, and ductility, and these complications pose significant challenges in advancing the science and engineering of these metals. In hcp metals, generalized plasticity requires the activation of slip on pyramidal planes, but the structure, motion, and cross-slip of the associated dislocations are not well established even though they determine ductility and influence strengthening. Here, atomistic simulations in Mg reveal the unusual mechanism of dislocation cross-slip between pyramidal I and II planes, which occurs by cross-slip of the individual partial dislocations. The energy barrier is controlled by a fundamental step/jog energy and the near-core energy difference between pyramidal dislocations. The near-core energy difference can be changed by nonglide stresses, leading to tension-compression asymmetry and even a switch in absolute stability from one glide plane to the other, both features observed experimentally in Mg, Ti, and their alloys. The unique cross-slip mechanism is governed by common features of the generalized stacking fault energy surfaces of hcp pyramidal planes and is thus expected to be generic to all hcp metals. An analytical model is developed to predict the cross-slip barrier as a function of the near-core energy difference and applied stresses and quantifies the controlling features of cross-slip and pyramidal I/II stability across the family of hcp metals.

  19. Stick-slip and Torsional Friction Factors in Inclined Wellbores

    Directory of Open Access Journals (Sweden)

    Aarsnes Ulf Jakob F.

    2018-01-01

    The model is shown to have a good match with the surface and downhole behavior of two deviated wellbores for depths ranging from 1500 to 3000 meters. In particular, the model replicates the amplitude and period of the oscillations, in both the topside torque and the downhole RPM, as caused by the along-string stick slip. It is further shown that by using the surface behavior of the drill-string during rotational startup, an estimate of the static and dynamic friction factors along the wellbore can be obtained, even during stick-slip oscillations, if axial tension in the drillstring is considered. This presents a possible method to estimate friction factors in the field when off-bottom stick slip is encountered, and points in the direction of avoiding stick slip through the design of an appropriate torsional start-up procedure without the need of an explicit friction test.

  20. Foot strike and injury rates in endurance runners: a retrospective study.

    Science.gov (United States)

    Daoud, Adam I; Geissler, Gary J; Wang, Frank; Saretsky, Jason; Daoud, Yahya A; Lieberman, Daniel E

    2012-07-01

    This retrospective study tests if runners who habitually forefoot strike have different rates of injury than runners who habitually rearfoot strike. We measured the strike characteristics of middle- and long-distance runners from a collegiate cross-country team and quantified their history of injury, including the incidence and rate of specific injuries, the severity of each injury, and the rate of mild, moderate, and severe injuries per mile run. Of the 52 runners studied, 36 (69%) primarily used a rearfoot strike and 16 (31%) primarily used a forefoot strike. Approximately 74% of runners experienced a moderate or severe injury each year, but those who habitually rearfoot strike had approximately twice the rate of repetitive stress injuries than individuals who habitually forefoot strike. Traumatic injury rates were not significantly different between the two groups. A generalized linear model showed that strike type, sex, race distance, and average miles per week each correlate significantly (P strike have significantly higher rates of repetitive stress injury than those who mostly forefoot strike. This study does not test the causal bases for this general difference. One hypothesis, which requires further research, is that the absence of a marked impact peak in the ground reaction force during a forefoot strike compared with a rearfoot strike may contribute to lower rates of injuries in habitual forefoot strikers.

  1. Shoe-Floor Interactions in Human Walking With Slips: Modeling and Experiments.

    Science.gov (United States)

    Trkov, Mitja; Yi, Jingang; Liu, Tao; Li, Kang

    2018-03-01

    Shoe-floor interactions play a crucial role in determining the possibility of potential slip and fall during human walking. Biomechanical and tribological parameters influence the friction characteristics between the shoe sole and the floor and the existing work mainly focus on experimental studies. In this paper, we present modeling, analysis, and experiments to understand slip and force distributions between the shoe sole and floor surface during human walking. We present results for both soft and hard sole material. The computational approaches for slip and friction force distributions are presented using a spring-beam networks model. The model predictions match the experimentally observed sole deformations with large soft sole deformation at the beginning and the end stages of the stance, which indicates the increased risk for slip. The experiments confirm that both the previously reported required coefficient of friction (RCOF) and the deformation measurements in this study can be used to predict slip occurrence. Moreover, the deformation and force distribution results reported in this study provide further understanding and knowledge of slip initiation and termination under various biomechanical conditions.

  2. Lightning Strike in Pregnancy With Fetal Injury.

    Science.gov (United States)

    Galster, Kellen; Hodnick, Ryan; Berkeley, Ross P

    2016-06-01

    Injuries from lightning strikes are an infrequent occurrence, and are only rarely noted to involve pregnant victims. Only 13 cases of lightning strike in pregnancy have been previously described in the medical literature, along with 7 additional cases discovered within news media reports. This case report presents a novel case of lightning-associated injury in a patient in the third trimester of pregnancy, resulting in fetal ischemic brain injury and long-term morbidity, and reviews the mechanics of lightning strikes along with common injury patterns of which emergency providers should be aware. Copyright © 2016 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  3. Tectonic Implication of the 5th March 2005, Doublet Earthquake in Ilan, Taiwan

    Directory of Open Access Journals (Sweden)

    En-Chao Yeh

    2016-01-01

    Full Text Available The 5th March 2005 earthquake doublet focal mechanism was determined as strike-slip faulting from Harvard and BATS moment tensor inversion. However, based on first motion polarities, the first shock has a normal focal mechanism (Wu et al. 2008a. This discrepancy has caused a debate over the focal mechanism solution because different focal mechanisms have different tectonic implications. Based on the dislocation determination from Global Position System (GPS measurements, we find this event includes both tensile and strike-slip components. This finding illustrates the reason for the differences in the determined focal mechanisms using two different types of seismic data and analyzing methods. Field mapping and microstructure examination results indicate that the ductile deformation around the study area was characterized by the evolution from transpression to transtension with a predominant strike-slip component, but present-day active structures may be dominated by normal faulting. Thus, the active tensile slip result determined from dislocation modeling strongly suggests that the back arc extension of the Okinawa trough influences the stress state in this region, and changes the major transtension from strike-slip faulting to normal faulting.

  4. Wall-slip of highly filled powder injection molding compounds: Effect of flow channel geometry and roughness

    Science.gov (United States)

    Hausnerova, Berenika; Sanetrnik, Daniel; Paravanova, Gordana

    2014-05-01

    The paper deals with the rheological behavior of highly filled compounds proceeded via powder injection molding (PIM) and applied in many sectors of industry (automotive, medicine, electronic or military). Online rheometer equipped with slit dies varying in surface roughness and dimensions was applied to investigate the wall-slip as a rheological phenomenon, which can be considered as a parameter indicating the separation of compound components (polymer binder and metallic powder) during high shear rates when injection molded.

  5. effects of strike cost on economic development in nigeria

    African Journals Online (AJOL)

    USER

    same firm, in other firms even in other industries (Kempner, 1980). For example ... The main purpose of this paper is to examine the strike cost and productivity in. Nigeria. ... Obnoxious Policies: Workers do go on strike when management makes obnoxious ... ASUU had to go on strike; the FGN had rescinded the decision.

  6. Rate-Dependent Slip of Newtonian Liquid at Smooth Surfaces

    International Nuclear Information System (INIS)

    Zhu, Yingxi; Granick, Steve

    2001-01-01

    Newtonian fluids were placed between molecularly smooth surfaces whose spacing was vibrated at spacings where the fluid responded as a continuum. Hydrodynamic forces agreed with predictions from the no-slip boundary condition only provided that flow rate (peak velocity normalized by spacing) was low, but implied partial slip when it exceeded a critical level, different in different systems, correlated with contact angle (surface wettability). With increasing flow rate and partially wetted surfaces, hydrodynamic forces became up to 2--4 orders of magnitude less than expected by assuming the no-slip boundary condition that is commonly stated in textbooks

  7. Influence of movement regime of stick-slip process on the size distribution of accompanying acoustic emission characteristics

    Science.gov (United States)

    Matcharashvili, Teimuraz; Chelidze, Tamaz; Zhukova, Natalia; Mepharidze, Ekaterine; Sborshchikov, Alexander

    2010-05-01

    of stick slip movement has been maintained. The AE accompanying the elementary slip events of stick-slip process were recorded on a PC sound card. The sensor for the AE was a lead circonate-titanate with a natural frequency of 100 KHz. In order to ensure standard conditions in each experiment, sliding surfaces were sanded up by sandpaper and cleaned of a dust. AE data analysis consisted of signal conditioning, filtering, and correct wave trains separation. Onset time of AE was determined at a minimun of Akaike Information Criterion. Afterwards time series of AE characteristics such as: recurrence times between consecutive AE bursts as well as time intervals between their maximums, duration of AE bursts, energy and power of AE, max by modulus of AE wave train amplitudes, etc. have been compiled. Cumulative probability distributions for all these data sets have been constructed and tested on the subject of GR type power law relation. It was found that characteristics of AE of stick slip process are strongly depending on the movement regime. Number of registered AE essentially increased for stiffer spring. At the same time recurrence times and emitted AE energy decreases. Power law type relation have not been observed for all AE characteristics and not for all considered regimes of movement. Power law relation, close to observed for real seismicity, was found for power of AE time series at stiffer springs. It is interesting that recurrence times between maximums of consecutive AE bursts and duration of AE bursts, reveal b in the range of 0.6-1.65. These results point that experimental conditions of stick slip process including movement regimes should be selected with care to ensure similarity between model and natural seismicity distributional characteristics.

  8. Forward to the Past: Strikes and Striking as Dialogue by other ...

    African Journals Online (AJOL)

    In Nigeria, from the colonial period to the present, the employment of strikes and protests by nationalists, Nigerian workers and civil society groups has been established as one of the potent means of conveying viewpoints, positions as well as the demand for equality, fairness, social justice and reforms. It has been used as ...

  9. Technological control of slip casting by the method of PMR

    International Nuclear Information System (INIS)

    Rozental', O.M.; Toropov, Yu.S.; Sobolev, A.S.; Pliner, S.Yu.; Demina, T.E.; Permikina, I.M.

    1980-01-01

    The method of proton magnetic resonance (PMR) is suggested for operational chemico-technological control of slip casting made of oxides of metals in the technology of technical ceramics. PMR spectra of finely dispersed slip casting made of aluminium and zirconium oxides (0.9 mol. of the ZrO 2 shake + 0.1 V 2 O 3 ) are analysed. It is shown that the quality of slip casting out of aqueous suspensions of aluminium and zirconium oxides is abruptly reduced if dP/dW (P - parameter of the PMR line shape, W - humidity) decrease. It is established that slip casting made of zirconium oxide should not be kept in the air more than 5 days, and that of aluminium oxide, more than 3 days at room temperature and should not be exposed to high (> 105 deg C) temperatures. The quality of slip casting is reduced in the regime of too energetic electrosedimentation the optimum regime of electrosedimentation is approximately 5/3 under the conditions of the above experiment

  10. Systematic deficiency of aftershocks in areas of high coseismic slip for large subduction zone earthquakes

    Science.gov (United States)

    Wetzler, Nadav; Lay, Thorne; Brodsky, Emily E.; Kanamori, Hiroo

    2018-01-01

    Fault slip during plate boundary earthquakes releases a portion of the shear stress accumulated due to frictional resistance to relative plate motions. Investigation of 101 large [moment magnitude (Mw) ≥ 7] subduction zone plate boundary mainshocks with consistently determined coseismic slip distributions establishes that 15 to 55% of all master event–relocated aftershocks with Mw ≥ 5.2 are located within the slip regions of the mainshock ruptures and few are located in peak slip regions, allowing for uncertainty in the slip models. For the preferred models, cumulative deficiency of aftershocks within the central three-quarters of the scaled slip regions ranges from 15 to 45%, increasing with the total number of observed aftershocks. The spatial gradients of the mainshock coseismic slip concentrate residual shear stress near the slip zone margins and increase stress outside the slip zone, driving both interplate and intraplate aftershock occurrence near the periphery of the mainshock slip. The shear stress reduction in large-slip regions during the mainshock is generally sufficient to preclude further significant rupture during the aftershock sequence, consistent with large-slip areas relocking and not rupturing again for a substantial time. PMID:29487902

  11. Slip resistance of casual footwear: implications for falls in older adults.

    Science.gov (United States)

    Menz, H B; Lord, S T; McIntosh, A S

    2001-01-01

    A large proportion of falls in older people are caused by slipping. Previous occupational safety research suggests that inadequate footwear may contribute to slipping accidents; however, no studies have assessed the slip resistance of casual footwear. To evaluate the slip resistance of different types of casual footwear over a range of common household surfaces. The slip resistance of men's Oxford shoes and women's fashion shoes with different heel configurations was determined by measuring the dynamic coefficient of friction (DCoF) at heel contact (in both dry and wet conditions) on a bathroom tile, concrete, vinyl flooring and a terra cotta tile using a specially-designed piezoelectric force plate apparatus. Analysis of variance revealed significant shoe, surface, and shoe-surface interaction effects. Men's Oxford shoes exhibited higher average DCoF values than the women's fashion shoes, however, none of the shoes could be considered safe on wet surfaces. Application of a textured sole material did not improve slip resistance of any of the shoes on wet surfaces. Heel geometry influences the slip resistance of casual footwear on common household surfaces. The suboptimal performance of all of the test shoes on wet surfaces suggests that a safety standard for casual footwear is required to assist in the development of safe footwear for older people. Copyright 2001 S. Karger AG, Basel

  12. Source parameters of the Bay of Bengal earthquake of 21 May 2014 and related seismotectonics of 85°E and 90°E ridges

    Science.gov (United States)

    Prakash, Rajesh; Prajapati, Sanjay Kumar; Srivastava, Hari Narain

    2018-01-01

    Source parameters of the Bay of Bengal earthquake of 21 May 2014 have been studied using full waveform inversion. Its source mechanism thus determined the orientation of the strike slip faulting as NW-SE/NE-SW. The occurrence of past earthquakes along the NE-SW nodal plane suggested its preference as the main fault which could result from the transmission of stresses from the Indian plate boundary. High stress drop of this earthquake (216 bar) is attributed to its location in the intraplate region, strike slip faulting and focus in the colder upper mantle. Comparison of the stress drop of deeper focus Hindukush earthquakes with that of the Bay of Bengal earthquake showed a smaller felt radius due to fractured lithosphere in the Himalayas vis-a-vis more efficient propagation of seismic waves in the peninsular region from the source region of this recent earthquake. The seismological evidence presented for the 85°E and 90°E ridges shows the predominance of strike slip faulting with thrusting on both the ridges. Integrating their source mechanism with that of the May 2014 earthquake, it could be inferred that the Bay of Bengal region (excluding Andaman Sumatra subduction zone) is characterised predominantly by strike slip faulting in the region north of latitude 20°N and strike slip with thrusting in the remaining portion.

  13. Turbulent flows over superhydrophobic surfaces with shear-dependent slip length

    Science.gov (United States)

    Khosh Aghdam, Sohrab; Seddighi, Mehdi; Ricco, Pierre

    2015-11-01

    Motivated by recent experimental evidence, shear-dependent slip length superhydrophobic surfaces are studied. Lyapunov stability analysis is applied in a 3D turbulent channel flow and extended to the shear-dependent slip-length case. The feedback law extracted is recognized for the first time to coincide with the constant-slip-length model widely used in simulations of hydrophobic surfaces. The condition for the slip parameters is found to be consistent with the experimental data and with values from DNS. The theoretical approach by Fukagata (PoF 18.5: 051703) is employed to model the drag-reduction effect engendered by the shear-dependent slip-length surfaces. The estimated drag-reduction values are in very good agreement with our DNS data. For slip parameters and flow conditions which are potentially realizable in the lab, the maximum computed drag reduction reaches 50%. The power spent by the turbulent flow on the walls is computed, thereby recognizing the hydrophobic surfaces as a passive-absorbing drag-reduction method, as opposed to geometrically-modifying techniques that do not consume energy, e.g. riblets, hence named passive-neutral. The flow is investigated by visualizations, statistical analysis of vorticity and strain rates, and quadrants of the Reynolds stresses. Part of this work was funded by Airbus Group. Simulations were performed on the ARCHER Supercomputer (UKTC Grant).

  14. Shear Stress-Relative Slip Relationship at Concrete Interfaces

    Directory of Open Access Journals (Sweden)

    Keun-Hyeok Yang

    2016-01-01

    Full Text Available This study develops a simple and rational shear stress-relative slip model of concrete interfaces with monolithic castings or smooth construction joints. In developing the model, the initial shear cracking stress and relative slip amount at peak stress were formulated from a nonlinear regression analysis using test data for push-off specimens. The shear friction strength was determined from the generalized equations on the basis of the upper-bound theorem of concrete plasticity. Then, a parametric fitting analysis was performed to derive equations for the key parameters determining the shapes of the ascending and descending branches of the shear stress-relative slip curve. The comparisons of predictions and measurements obtained from push-off tests confirmed that the proposed model provides superior accuracy in predicting the shear stress-relative slip relationship of interfacial shear planes. This was evidenced by the lower normalized root mean square error than those in Xu et al.’s model and the CEB-FIB model, which have many limitations in terms of the roughness of the substrate surface along an interface and the magnitude of equivalent normal stress.

  15. Dynamic growth of slip surfaces in catastrophic landslides.

    Science.gov (United States)

    Germanovich, Leonid N; Kim, Sihyun; Puzrin, Alexander M

    2016-01-01

    This work considers a landslide caused by the shear band that emerges along the potential slip (rupture) surface. The material above the band slides downwards, causing the band to grow along the slope. This growth may first be stable (progressive), but eventually becomes dynamic (catastrophic). The landslide body acquires a finite velocity before it separates from the substrata. The corresponding initial-boundary value problem for a dynamic shear band is formulated within the framework of Palmer & Rice's ( Proc. R. Soc. Lond. A 332 , 527-548. (doi:10.1098/rspa.1973.0040)) approach, which is generalized to the dynamic case. We obtain the exact, closed-form solution for the band velocity and slip rate. This solution assesses when the slope fails owing to a limiting condition near the propagating tip of the shear band. Our results are applicable to both submarine and subaerial landslides of this type. It appears that neglecting dynamic (inertia) effects can lead to a significant underestimation of the slide size, and that the volumes of catastrophic slides can exceed the volumes of progressive slides by nearly a factor of 2. As examples, we consider the Gaviota and Humboldt slides offshore of California, and discuss landslides in normally consolidated sediments and sensitive clays. In particular, it is conceivable that Humboldt slide is unfinished and may still displace a large volume of sediments, which could generate a considerable tsunami. We show that in the case of submarine slides, the effect of water resistance on the shear band dynamics may frequently be limited during the slope failure stage. For a varying slope angle, we formulate a condition of slide cessation.

  16. Slip and fall risk on ice and snow:identification, evaluation and prevention

    OpenAIRE

    Gao, Chuansi

    2004-01-01

    Slip and fall accidents and associated injuries on ice and snow are prevalent among outdoor workers and the general public in winter in many regions of the world. To understand and tackle this multi-factorial problem, a multidisciplinary approach was used to identify and evaluate slip and fall risks, and to propose recommendations for prevention of slips and falls on icy and snowy surfaces. Objectives were to present a systems perspective of slip and fall accidents and related risk factors; t...

  17. "Thunderstruck": penetrating thoracic injury from lightning strike.

    Science.gov (United States)

    van Waes, Oscar J F; van de Woestijne, Pieter C; Halm, Jens A

    2014-04-01

    Lightning strike victims are rarely presented at an emergency department. Burns are often the primary focus. This case report describes the improvised explosive device like-injury to the thorax due to lightning strike and its treatment, which has not been described prior in (kerauno)medicine. Penetrating injury due to blast from lightning strike is extremely rare. These "shrapnel" injuries should however be ruled out in all patients struck by lightning. Copyright © 2013 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

  18. Triggered surface slips in the Salton Trough associated with the 1999 Hector Mine, California, earthquake

    Science.gov (United States)

    Rymer, M.J.; Boatwright, J.; Seekins, L.C.; Yule, J.D.; Liu, J.

    2002-01-01

    Surface fracturing occurred along the southern San Andreas, Superstition Hills, and Imperial faults in association with the 16 October 1999 (Mw 7.1) Hector Mine earthquake, making this at least the eighth time in the past 31 years that a regional earthquake has triggered slip along faults in the Salton Trough. Fractures associated with the event formed discontinuous breaks over a 39-km-long stretch of the San Andreas fault, from the Mecca Hills southeastward to Salt Creek and Durmid Hill, a distance from the epicenter of 107 to 139 km. Sense of slip was right lateral; only locally was there a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 13 mm. Maximum slip values in 1999 and earlier triggered slips are most common in the central Mecca Hills. Field evidence indicates a transient opening as the Hector Mine seismic waves passed the southern San Andreas fault. Comparison of nearby strong-motion records indicates several periods of relative opening with passage of the Hector Mine seismic wave-a similar process may have contributed to the field evidence of a transient opening. Slip on the Superstition Hills fault extended at least 9 km, at a distance from the Hector Mine epicenter of about 188 to 196 km. This length of slip is a minimum value, because we saw fresh surface breakage extending farther northwest than our measurement sites. Sense of slip was right lateral; locally there was a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 18 mm, with the largest amounts found distributed (or skewed) away from the Hector Mine earthquake source. Slip triggered on the Superstition Hills fault commonly is skewed away from the earthquake source, most notably in 1968, 1979, and 1999. Surface slip on the Imperial fault and within the Imperial Valley extended about 22 km, representing a distance from the Hector Mine epicenter of about 204 to 226 km. Sense of slip dominantly was right lateral; the right-lateral component of slip

  19. Option Strike Price and Managerial Investment Decisions

    Institute of Scientific and Technical Information of China (English)

    刘鸿雁; 张维

    2003-01-01

    The manager′s investment decisions is modeled when the manager is risk-averse and has stock options as compensation. It is found that the strike price of options is crucial to the investment incentives of managers, and that the correct value, or interval of values, of managerial stock option strike price can bring stockholder and manager interests in agreement.

  20. Asymmetric Barrier Lyapunov Function-Based Wheel Slip Control for Antilock Braking System

    Directory of Open Access Journals (Sweden)

    Xiaolei Chen

    2015-01-01

    Full Text Available As an important device of the aircraft landing system, the antilock braking system (ABS has a function to avoid aircraft wheels self-locking. To deal with the strong nonlinear characteristics, complex nonlinear control schemes are applied in ABS. However, none of existing control schemes focus on the braking operating status, which directly reflects wheels self-locking degree. In this paper, the braking operating status region is divided into three regions: the healthy region, the light slip region, and the deep slip region. An ABLF-based wheel slip controller is proposed for ABS to constrain the braking system operating status in the healthy region and the light slip region. Therefore the ABS will be prevented from operating in the deep slip region. Under the proposed control scheme, self-locking is avoided completely and zero steady state error tracking of the wheel optimal slip ratio is implemented. The Hardware-In-Loop (HIL experiments have validated the effectiveness of the proposed controller.

  1. The Sierra de Cabral range: a restraining bend related to the Sierra Ballena shear zone in Dom Feliciano belt

    International Nuclear Information System (INIS)

    Masquelin, H.

    2010-01-01

    Restraining and releasing bends occurring in all crustal environments are common but enigmatic features of strike-slip fault systems. They can be reported in all scales of observation. Regional-scale restraining bends are sites of mountain building, transpressional deformation and basement exhumation. Releasing bends are sites of subsidence, transtensional deformation and pull-apart basins. The Dom Feliciano Belt of Southern Uruguay has two main structures observed from the outer space: (i) the Sierra Ballena Shear Zone and (ii) the Sierra de Cabral flexure located to the SW of the former. Although a transpressional regime is commonly accepted for the Dom Feliciano Belt, the available tectonic models do not provide satisfactory explanations for its building mechanism. A restraining bend is proposed at the SW termination of Sierra Ballena strike-slip ductile shear zone. In a key-area (Alvariza Range) the relationship between the Zanja del Tigre volcanic-detritic and the calcareous succession shows three en-échelon upright bends of the same quartzite hanging-wall between two sub-vertical strike-slip faults, suggesting the existence of a shortened strike-slip duplex operating in viscous-elastic rheology. The deformation partitioning includes strike-slip and dip-slip simple-shear components as well as one contractional pure-shear component. Because restraining bends were scarcely described in Neoproterozoic low-grade regional exhumation conditions, this structural framework would be a natural laboratory to study fault kinematics, fault dynamics, their associated deformation and the tectonic and erosion constraints related to the exhumation of many crystalline terrains

  2. Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

    Directory of Open Access Journals (Sweden)

    T. van der Werf

    2017-12-01

    Full Text Available The rheology of lower crust and its transient behavior in active strike-slip plate boundaries remain poorly understood. To address this issue, we analyzed a suite of granulite and lherzolite xenoliths from the upper Pleistocene–Holocene San Quintín volcanic field of northern Baja California, Mexico. The San Quintín volcanic field is located 20 km east of the Baja California shear zone, which accommodates the relative movement between the Pacific plate and Baja California microplate. The development of a strong foliation in both the mafic granulites and lherzolites, suggests that a lithospheric-scale shear zone exists beneath the San Quintín volcanic field. Combining microstructural observations, geothermometry, and phase equilibria modeling, we estimated that crystal-plastic deformation took place at temperatures of 750–890 °C and pressures of 400–560 MPa, corresponding to 15–22 km depth. A hot crustal geotherm of 40 ° C km−1 is required to explain the estimated deformation conditions. Infrared spectroscopy shows that plagioclase in the mafic granulites is relatively dry. Microstructures are interpreted to show that deformation in both the uppermost lower crust and upper mantle was accommodated by a combination of dislocation creep and grain-size-sensitive creep. Recrystallized grain size paleopiezometry yields low differential stresses of 12–33 and 17 MPa for plagioclase and olivine, respectively. The lower range of stresses (12–17 MPa in the mafic granulite and lherzolite xenoliths is interpreted to be associated with transient deformation under decreasing stress conditions, following an event of stress increase. Using flow laws for dry plagioclase, we estimated a low viscosity of 1.1–1.3×1020 Pa ⋅ s for the high temperature conditions (890 °C in the lower crust. Significantly lower viscosities in the range of 1016–1019 Pa ⋅ s, were estimated using flow laws for wet plagioclase. The

  3. Localization in the brittle field: the role of frictional properties and implications for earthquake slip

    Science.gov (United States)

    Tullis, T.

    2003-04-01

    Rotary shear friction experiments on layers of simulated gouge and on bare surfaces of rock that generate gouge, with displacements up to several meters, show that in some situations slip becomes localized. The two constitutive parameters that control whether slip localizes are the displacement and the velocity dependence of the shear strength. When slip-weakening and velocity-weakening both occur, slip localizes, since the overall resistance is reduced and less energy is dissipated. Similarly, when slip- and velocity-strengthening both occur, slip delocalizes, again because less energy is dissipated. If the variation of shear resistance with slip and velocity are of opposite sign, then the magnitude of the slip and rate dependencies and the amount and rate of slip determine whether localization or delocalization occur. In most laboratory experiments, the displacement dependence of the strength is minimal and the velocity dependence controls the tendency for localization. However, some experiments illustrate the situation in which the displacement dependence dominates. Regardless of their underlying causes, slip- and velocity-weakening result in unstable slip in compliant systems. Consequently unstable slip and localization are linked through these constitutive properties. This connection between unstable slip, displacement/velocity-weakening, and localization suggests that slip on faults that occurs primarily via earthquakes will be localized. However, localization is more complicated on natural faults because laboratory faults are geometrically simpler than natural ones. Laboratory faults are smooth at long wavelengths, whereas natural faults have approximately a self-similar surface roughness, the amplitude of irregularities being proportional to their wavelength. Thus, slip on a localized surface in a laboratory fault can continue indefinitely, whereas slip on natural faults is likely to require fracture of new wall rock as sufficient slip brings higher

  4. Stability Analysis of Static Slip-Energy Recovery Drive via ...

    African Journals Online (AJOL)

    The stability of the sub synchronous static slip energy recovery scheme for the speed control of slip-ring induction motor is presented. A set of nonlinear differential equations which describe the system dynamics are derived and linearized about an operating point using perturbation technique. The Eigenvalue analysis of the ...

  5. Surgical results of the slipped medial rectus muscle after hang back recession surgery

    Directory of Open Access Journals (Sweden)

    Yasar Duranoglu

    2014-12-01

    Full Text Available AIM:To analyze the surgical results of a slipped medial rectus muscle (MRM after hang back recession surgery for esotropia.METHODS:Twenty-one patients who underwent re-exploration for diagnosed slipped muscle after hang back recession surgery were included in this retrospective study. Dynamic magnetic resonance imaging was performed to identify the location of the slipped muscle. Ocular motility was evaluated with assessment with prism and cover test in gaze at cardinal positions. The operations were performed by the same consultant. Intraoperative forced duction test was performed under general anesthesia. The empty sheath of the slipped MRM was resected and the muscle was advanced to the original insertion site in all patients.RESULTS:The average age of 21 patients who hadconsecutive exotropia with a slipped MRM at the time of presentation was 17.4±5.4y (5-50y. The average duration between the first operation and the diagnosis of the slipped muscle was 25mo (12 to 36mo. The mean follow up after the corrective surgery was 28mo. The mean preoperative adduction limitation in the field of action of the slipped muscle was -2.26 (ranging from -1 to -4. All patients had full adduction postoperatively.CONCLUSION:The diagnosis of the slipped muscle should be confirmed during the strabismus surgery. The slipped muscle may be caused due to insufficient suture and excessive rubbing of the eye. When divergent strabismus is observed after the recession of the MRM, a slipped muscle should be considered in the differential diagnosis.

  6. Effects of footwear and strike type on running economy.

    Science.gov (United States)

    Perl, Daniel P; Daoud, Adam I; Lieberman, Daniel E

    2012-07-01

    This study tests if running economy differs in minimal shoes versus standard running shoes with cushioned elevated heels and arch supports and in forefoot versus rearfoot strike gaits. We measured the cost of transport (mL O(2)·kg(-1)·m(-1)) in subjects who habitually run in minimal shoes or barefoot while they were running at 3.0 m·s(-1) on a treadmill during forefoot and rearfoot striking while wearing minimal and standard shoes, controlling for shoe mass and stride frequency. Force and kinematic data were collected when subjects were shod and barefoot to quantify differences in knee flexion, arch strain, plantar flexor force production, and Achilles tendon-triceps surae strain. After controlling for stride frequency and shoe mass, runners were 2.41% more economical in the minimal-shoe condition when forefoot striking and 3.32% more economical in the minimal-shoe condition when rearfoot striking (P forefoot and rearfoot striking did not differ significantly in cost for either minimal- or standard-shoe running. Arch strain was not measured in the shod condition but was significantly greater during forefoot than rearfoot striking when barefoot. Plantar flexor force output was significantly higher in forefoot than in rearfoot striking and in barefoot than in shod running. Achilles tendon-triceps surae strain and knee flexion were also lower in barefoot than in standard-shoe running. Minimally shod runners are modestly but significantly more economical than traditionally shod runners regardless of strike type, after controlling for shoe mass and stride frequency. The likely cause of this difference is more elastic energy storage and release in the lower extremity during minimal-shoe running.

  7. New active faults on Eurasian-Arabian collision zone: Tectonic activity of Özyurt and Gülsünler faults (Eastern Anatolian Plateau, Van-Turkey)

    Energy Technology Data Exchange (ETDEWEB)

    Dicle, S.; Üner, S.

    2017-11-01

    The Eastern Anatolian Plateau emerges from the continental collision between Arabian and Eurasian plates where intense seismicity related to the ongoing convergence characterizes the southern part of the plateau. Active deformation in this zone is shared by mainly thrust and strike-slip faults. The Özyurt thrust fault and the Gülsünler sinistral strike-slip fault are newly determined fault zones, located to the north of Van city centre. Different types of faults such as thrust, normal and strike-slip faults are observed on the quarry wall excavated in Quaternary lacustrine deposits at the intersection zone of these two faults. Kinematic analysis of fault-slip data has revealed coeval activities of transtensional and compressional structures for the Lake Van Basin. Seismological and geomorphological characteristics of these faults demonstrate the capability of devastating earthquakes for the area.

  8. New active faults on Eurasian-Arabian collision zone: Tectonic activity of Özyurt and Gülsünler faults (Eastern Anatolian Plateau, Van-Turkey)

    International Nuclear Information System (INIS)

    Dicle, S.; Üner, S.

    2017-01-01

    The Eastern Anatolian Plateau emerges from the continental collision between Arabian and Eurasian plates where intense seismicity related to the ongoing convergence characterizes the southern part of the plateau. Active deformation in this zone is shared by mainly thrust and strike-slip faults. The Özyurt thrust fault and the Gülsünler sinistral strike-slip fault are newly determined fault zones, located to the north of Van city centre. Different types of faults such as thrust, normal and strike-slip faults are observed on the quarry wall excavated in Quaternary lacustrine deposits at the intersection zone of these two faults. Kinematic analysis of fault-slip data has revealed coeval activities of transtensional and compressional structures for the Lake Van Basin. Seismological and geomorphological characteristics of these faults demonstrate the capability of devastating earthquakes for the area.

  9. New insights into the distribution and evolution of the Cenozoic Tan-Lu Fault Zone in the Liaohe sub-basin of the Bohai Bay Basin, eastern China

    Science.gov (United States)

    Huang, Lei; Liu, Chi-yang; Xu, Chang-gui; Wu, Kui; Wang, Guang-yuan; Jia, Nan

    2018-01-01

    As the largest strike-slip fault system in eastern China, the northeast-trending Tan-Lu Fault Zone (TLFZ) is a significant tectonic element contributing to the Mesozoic-Cenozoic regional geologic evolution of eastern Asia, as well as to the formation of ore deposits and oilfields. Because of the paucity of data, its distribution and evolutionary history in the offshore Liaohe sub-basin of the northern Bohai Bay Basin (BBB) are still poorly understood. Investigations of the strike-slip fault system in the western portion of the offshore Liaohe sub-basin via new seismic data provide us with new insights into the characteristics of the Cenozoic TLFZ. Results of this study show that Cenozoic dextral strike-slip faults occurred near the center of the Liaoxi graben in the offshore Liaohe sub-basin; these strike-slip faults connect with their counterparts to the north, the western part of the onshore Liaohe sub-basin, and have similar characteristics to those in other areas of the BBB in terms of kinematics, evolutionary history, and distribution; consequently, these faults are considered as the western branch of the TLFZ. All strike-slip faults within the Liaoxi graben merge at depth with a central subvertical basement fault induced by the reactivation of a pre-existing strike-slip basement fault, the pre-Cenozoic TLFZ. Data suggest that the TLFZ across the whole Liaohe sub-basin comprises two branches and that the Cenozoic distribution of this system was inherited from the pre-Cenozoic TLFZ. This characteristic distribution might be possessed by the whole TLFZ, thus the new understandings about the distribution and evolutionary model of the TLFZ in this study can be inferred in many research fields along the whole fault zone, such as regional geology, ore deposits, petroleum exploration and earthquake hazard.

  10. Analogue modelling of strike-slip fault propagation across a rheological/morphological crustal anisotropy: implications for the morphotectonic evolution of the Gloria Fault - Tore Madeira Rise area in NE Atlantic.

    Science.gov (United States)

    Tomás, Ricardo; Rosas, Filipe M.; Duarte, João C.; Terrinha, Pedro; Kullberg, Maria C.; Almeida, Jaime; Barata, Frederico; Carvalho, Bruno; Almeida, Pedro

    2015-04-01

    The Gloria Fault (GF) marks the E-W dextral transcurrent plate boundary between Eurasia and Africa in NE Atlantic, displaying complying high magnitude (historical and instrumental) seismic activity (e.g. M=7.1 in 1939 and M=8.4 in 1941, Bufforn et al., 1988), and cutting across a NNE-SSW 1000 km long bathymetric ridge: the so called Tore-Madeira Rise - TMR (rising in average 3km above the abyssal plain). The precise origin and tectono-magmatic evolution of the TMR is still not fully understood, although reported wide-angle refraction data points to a rheological configuration comprising an isostatically compensated thickened oceanic crust, possibly formed during a period of high accretion in the Mid-Atlantic Ridge (Pierce and Barton, 1991). Widespread evidence for volcanic activity has also been recognized, spanning from late Cretaceous to Present (Geldmacher et al. 2006, Merle et al. 2009), noticeably with the most recent volcanism (~500 Ky) occurring as tectonically aligned volcanic plugs, distributed along the E-W tectonic trend of the GF-related structures. To better understand the complex interference at play in this key area between the tectonic structures (essentially determined by the Gloria Fault system), the present and past magmatic activity and the resulting seafloor morphology, a series of dynamically scaled analogue modelling experiments have been conceived and carried out. The main focus of this experimental work was to decipher the potential influence of a rheological vs. morphological anisotropy (accounting for the TMR) on the lateral propagation of a major right-lateral strike-slip fault (representing the GF). The preliminary comparison of the obtained experimental results with the natural morphotectonic pattern in the study area reveals, not only a strong tectonic control of the ongoing volcanism, manifested by the observed preferred directions of aligned volcanic plugs, but also a so far unsuspected deflection/distributed pattern of several

  11. Slip Zone versus Damage Zone Micromechanics, Arima-Takasuki Tectonic Line, Japan

    Science.gov (United States)

    White, J. C.; Lin, A.

    2017-12-01

    The Arima-Takasuki Tectonic Line (ATTL) of southern Honshu, Japan is defined by historically active faults and multiple splays producing M7 earthquakes. The damage zone of the ATTL comprises a broad zone of crushed, comminuted and pulverized granite/rhyolite1,2containing cm-scale slip zones and highly comminuted injection veins. In this presentation, prior work on the ATTL fault rocks is extending to include microstructural characterization by transmission electron microscopy (TEM) from recent trenching of the primary slip zone, as well as secondary slip zones. This is necessary to adequately characterize the extremely fine-grained material (typically less than 1mm) in both damage and core zones. Damage zone material exhibits generally random textures3 whereas slip zones are macroscopically foliated, and compositionally layered, notwithstanding a fairly homogeneous protolith. The latter reflects fluid-rock interaction during both coseismic and interseismic periods. The slip zones are microstructurally heterogeneous at all scales, comprising not only cataclasites and phyllosilicate (clay)-rich gouge zones, but Fe/Mn pellets or clasts that are contained within gouge. These structures appear to have rolled and would suggest rapid recrystallization and/or growth. A central question related to earthquake recurrence along existing faults is the nature of the gouge. In both near-surface exposures and ongoing drilling at depth, "plastic" or "viscous" gouge zones comprise ultra-fine-grained clay-siliciclastic particles that would not necessarily respond in a simple frictional manner. Depending on whether the plastic nature of these slip zones develops during or after slip, subsequent focusing of slip within them could be complicated. 1 Mitchell, T.A., Ben-Zion, Y., Shimamoto, T., 2011. Ear. Planet. Sci. Lett. 308, 284-297. 2 Lin, A., Yamashita, K, Tanaka, M. J., 2013. Struc. Geol. 48, 3-13. 3 White, J.C., Lin, A. 2016. Proc. AGU Fall Mtg., T42-02 San Francisco.

  12. On flows of viscoelastic fluids under threshold-slip boundary conditions

    Science.gov (United States)

    Baranovskii, E. S.

    2018-03-01

    We investigate a boundary-value problem for the steady isothermal flow of an incompressible viscoelastic fluid of Oldroyd type in a 3D bounded domain with impermeable walls. We use the Fujita threshold-slip boundary condition. This condition states that the fluid can slip along a solid surface when the shear stresses reach a certain critical value; otherwise the slipping velocity is zero. Assuming that the flow domain is not rotationally symmetric, we prove an existence theorem for the corresponding slip problem in the framework of weak solutions. The proof uses methods for solving variational inequalities with pseudo-monotone operators and convex functionals, the method of introduction of auxiliary viscosity, as well as a passage-to-limit procedure based on energy estimates of approximate solutions, Korn’s inequality, and compactness arguments. Also, some properties and estimates of weak solutions are established.

  13. Strike Point Control on EAST Using an Isoflux Control Method

    International Nuclear Information System (INIS)

    Xing Zhe; Xiao Bingjia; Luo Zhengping; Walker, M. L.; Humphreys, D. A.

    2015-01-01

    For the advanced tokamak, the particle deposition and thermal load on the divertor is a big challenge. By moving the strike points on divertor target plates, the position of particle deposition and thermal load can be shifted. We could adjust the Poloidal Field (PF) coil current to achieve the strike point position feedback control. Using isoflux control method, the strike point position can be controlled by controlling the X point position. On the basis of experimental data, we establish relational expressions between X point position and strike point position. Benchmark experiments are carried out to validate the correctness and robustness of the control methods. The strike point position is successfully controlled following our command in the EAST operation. (paper)

  14. Lattice Boltzmann study of slip flow over structured surface with transverse slots

    Science.gov (United States)

    Chen, Wei; Wang, Kai; Wang, Lei; Hou, Guoxiang; Leng, Wenjun

    2018-04-01

    Slip flow over structured superhydrophobic surface with transverse slots is investigated by the lattice Boltzmann method. The Shan-Chen multiphase model is employed to simulate the flow over gas bubbles in the slots. The Carnahan-Starling equation of state is applied to obtain large density ratio. The interface thickness of the multiphase model is discussed. We find that the Cahn number Cn should be smaller than 0.02 when the temperature T = 0.5T c to restrict the influence of interface thickness on slip length. Influences of slot fraction on slip length is then studied, and the result is compared with single LB simulation of which the interface is treated as free-slip boundary. The slip length obtained by the multiphase model is a little smaller. After that, the shape of the liquid-gas interface is considered, and simulations with different initial protrusion angles and capillary numbers are performed. Effective slip length as a function of initial protrusion angle is obtained. The result is in qualitative agreement with a previous study and main features are reproduced. Furthermore, the influence of Capillary number Ca is studied. Larger Ca causes larger interface deformation and smaller slip length. But when the interface is concaving into the slot, this influence is less obvious.

  15. Numerical Simulation of Methane Slip in Dual Fuel Marine Engines

    OpenAIRE

    Han, Jaehyun; Jensen, Michael Vincent; Pang, Kar Mun; Walther, Jens Honore; Schramm, Jesper; Bae, Choongsik

    2017-01-01

    The methane slip is the problematic issue for the engines using natural gas(NG). Because methane is more powerful greenhouse gas (GHG) than CO2, understanding of the methane slip during gas exchange process of the engines is essential. In this study, the influence of the gas pipe geometry and the valve timings on the methane slip was investigated. MAN L28/32DF engine was modeled to simulate the gas exchange process of the four stroke NG-diesel dual fuel engines. The mesh size of the model was...

  16. Detection of slip from multiple sites in an artificial finger

    Energy Technology Data Exchange (ETDEWEB)

    Muridan, N; Chappell, P H; Cranny, A; White, N M [Electronic Systems and Devices Group, School of Electronics and Computer Science, University of Southampton, SO17 1BJ (United Kingdom); Cotton, D P J, E-mail: nm07r@ecs.soton.ac.u [Nanoscience Centre, University of Cambridge, Cambridge (United Kingdom)

    2009-07-01

    A Piezoelectric thick-film sensor is a good candidate for the extraction of information from object slip in hand prosthesis. Five slip sensors were fabricated on different linkages of an artificial hand. The signals from each sensor were compared to the output from the sensor mounted on the fingertip. An analysis of the output signals from all the sensors indicates that the linkage sensors also produce similar output signals to the fingertip sensor. In the next phase of the research, velocity and acceleration of the slipped object will be considered in the analysis.

  17. Back analysis of fault-slip in burst prone environment

    Science.gov (United States)

    Sainoki, Atsushi; Mitri, Hani S.

    2016-11-01

    In deep underground mines, stress re-distribution induced by mining activities could cause fault-slip. Seismic waves arising from fault-slip occasionally induce rock ejection when hitting the boundary of mine openings, and as a result, severe damage could be inflicted. In general, it is difficult to estimate fault-slip-induced ground motion in the vicinity of mine openings because of the complexity of the dynamic response of faults and the presence of geological structures. In this paper, a case study is conducted for a Canadian underground mine, herein called "Mine-A", which is known for its seismic activities. Using a microseismic database collected from the mine, a back analysis of fault-slip is carried out with mine-wide 3-dimensional numerical modeling. A back analysis is conducted to estimate the physical and mechanical properties of the causative fracture or shear zones. One large seismic event has been selected for the back analysis to detect a fault-slip related seismic event. In the back analysis, the shear zone properties are estimated with respect to moment magnitude of the seismic event and peak particle velocity (PPV) recorded by a strong ground motion sensor. The estimated properties are then validated through comparison with peak ground acceleration recorded by accelerometers. Lastly, ground motion in active mining areas is estimated by conducting dynamic analysis with the estimated values. The present study implies that it would be possible to estimate the magnitude of seismic events that might occur in the near future by applying the estimated properties to the numerical model. Although the case study is conducted for a specific mine, the developed methodology can be equally applied to other mines suffering from fault-slip related seismic events.

  18. Comparison of force, power, and striking efficiency for a Kung Fu strike performed by novice and experienced practitioners: preliminary analysis.

    Science.gov (United States)

    Neto, Osmar Pinto; Magini, Marcio; Saba, Marcelo M F; Pacheco, Marcos Tadeu Tavares

    2008-02-01

    This paper presents a comparison of force, power, and efficiency values calculated from Kung Fu Yau-Man palm strikes, when performed by 7 experienced and 6 novice men. They performed 5 palm strikes to a freestanding basketball, recorded by high-speed camera at 1000 Hz. Nonparametric comparisons and correlations showed experienced practitioners presented larger values of mean muscle force, mean impact force, mean muscle power, mean impact power, and mean striking efficiency, as is noted in evidence obtained for other martial arts. Also, an interesting result was that for experienced Kung Fu practitioners, muscle power was linearly correlated with impact power (p = .98) but not for the novice practitioners (p = .46).

  19. Episodic tremor and slip explained by fluid-enhanced microfracturing and sealing

    Science.gov (United States)

    Bernaudin, M.; Gueydan, F.

    2017-12-01

    A combination of non-volcanic tremor and transient slow slip events behaviors is commonly observed at plate interface, between locked/seismogenic zone at low depths and stable/ductile creep zone at larger depths. This association defines Episodic Tremor and Slip, systematically highlighted by over-pressurized fluids and near failure shear stress conditions. Here we propose a new mechanical approach that provides for the first time a mechanical and field-based explanation of the observed association between non-volcanic tremor and slow slip events. In contrast with more classical rate-and-state models, this physical model uses a ductile rheology with grain size sensitivity, fluid-driven microfracturing and sealing (e.g. grain size reduction and grain growth) and related pore fluid pressure fluctuations. We reproduce slow slip events by transient ductile strain localization as a result of fluid-enhanced microfracturing and sealing. Moreover, occurrence of macrofracturing during transient strain localization and local increase in pore fluid pressure well simulate non-volcanic tremor. Our model provides therefore a field-based explanation of episodic tremor and slip and moreover predicts the depth and temperature ranges of their occurrence in subduction zones. It implies furthermore that non-volcanic tremor and slow slip events are physically related.

  20. SLIP VELOCITY IN PULSED DISC AND DOUGHNUT EXTRACTION COLUMN

    Directory of Open Access Journals (Sweden)

    Mohammad Outokesh

    2011-09-01

    Full Text Available In the present work, slip velocity has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for four different liquid-liquid systems. The effects of operating variables including pulsation intensity and dispersed and continuous phase flow rates on slip velocity have been investigated. The existence of three different operational regimes, namely mixersettler, transition, and emulsion regimes, was observed when the energy input was changed. Empirical correlations are derived for prediction of the slip velocity in terms of operating variables, physical properties of the liquid systems, and column geometry for different regimes. Good agreement between prediction and experiments was found for all operating conditions that were investigated.

  1. Numerical study of the effect of Navier slip on the driven cavity flow

    KAUST Repository

    He, Qiaolin

    2009-10-01

    We study the driven cavity flow using the Navier slip boundary condition. Our results have shown that the Navier slip boundary condition removes the corner singularity induced by the no-slip boundary condition. In the low Reynolds number case, the behavior of the tangential stress is examined and the results are compared with the analytic results obtained in [14]. For the high Reynolds number, we study the effect of the slip on the critical Reynolds number for Hopf bifurcation. Our results show that the first Hopf bifurcation critical Reynolds number is increasing with slip length. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Preventive strike vs. false targets and protection in defense strategy

    International Nuclear Information System (INIS)

    Levitin, Gregory; Hausken, Kjell

    2011-01-01

    A defender allocates its resource between defending an object passively and striking preventively against an attacker seeking to destroy the object. With no preventive strike the defender distributes its entire resource between deploying false targets, which the attacker cannot distinguish from the genuine object, and protecting the object. If the defender strikes preventively, the attacker's vulnerability depends on its protection and on the defender's resource allocated to the strike. If the attacker survives, the object's vulnerability depends on the attacker's revenge attack resource allocated to the attacked object. The optimal defense resource distribution between striking preventively, deploying the false targets and protecting the object is analyzed. Two cases of the attacker strategy are considered: when the attacker attacks all of the targets and when it chooses a number of targets to attack. An optimization model is presented for making a decision about the efficiency of the preventive strike based on the estimated attack probability, dependent on a variety of model parameters.

  3. Fracture energy of stick-slip events in a large scale biaxial experiment

    International Nuclear Information System (INIS)

    Okubo, P.G.; Dieterich, J.H.

    1981-01-01

    The concept of apparent fracture energy for the shear failure process is employed by many authors in modeling earthquake sources as dynamically extending shear cracks. Using records of shear strain and relative displacement from stick-slip events generated along a simulated, prepared fault surface in a large (1.5m x 1.5m x 0.4m) granite block and a slip-weakening model for the fault, direct estimates of the apparent shear fracture energy of the stick-slip events have been obtained. For events generated on a finely ground fault surface, apparent fracture energy ranges from 0.06 J/m 2 at a normal stress of 1.1 MPa to 0.8 J/m 2 at a normal stress of 4.6 MPa. In contrast to estimates for tensile crack formation, we find that the apparent fracture energy of stick-slip events increases linearly with normal stress. The results for the slip-weakening model for the stick-slip events are generally consistent with constitutive fault models suggested by observations of stable sliding in smaller scale experiments

  4. Three-dimensional Upper Crustal Velocity and Attenuation Structures of the Central Tibetan Plateau from Local Earthquake Tomography

    Science.gov (United States)

    Zhou, B.; Liang, X.; Lin, G.; Tian, X.; Zhu, G.; Mechie, J.; Teng, J.

    2017-12-01

    A series of V-shaped conjugate strike-slip faults are the most spectacular geologic features in the central Tibetan plateau. A previous study suggested that this conjugate strike-slip fault system accommodates the east-west extension and coeval north-south contraction. Another previous study suggested that the continuous convergence between the Indian and Eurasian continents and the eastward asthenospheric flow generated lithospheric paired general-shear (PGS) deformation, which then caused the development of conjugate strike-slip faults in central Tibet. Local seismic tomography can image three dimensional upper-crustal velocity and attenuation structures in central Tibet, which will provide us with more information about the spatial distribution of physical properties and compositional variations around the conjugate strike-slip fault zone. Ultimately, this information could improve our understanding of the development mechanism of the conjugate strike-slip fault system. In this study, we collected 6,809 Pg and 2,929 Sg arrival times from 414 earthquakes recorded by the temporary SANDWICH and permanent CNSN networks from November 2013 to November 2015. We also included 300 P and 17 S arrival times from 12 shots recorded by the INDEPTH III project during the summer of 1998 in the velocity tomography. We inverted for preliminary Vp and Vp/Vs models using the SIMUL2000 tomography algorithm, and then relocated the earthquakes with these preliminary velocity models. After that, we inverted for the final velocity models with these improved source locations and origin times. After the velocity inversion, we performed local attenuation tomography using t* measurements from the same dataset with an already existing approach. There are correlated features in the velocity and attenuation structures. From the surface to 10 km depth, the study area is dominated by high Vp and Qp anomalies. However, from 10 km to 20 km depth, there is a low Vp and Qp zone distributed along the

  5. Late Neoproterozoic to Carboniferous genesis of A-type magmas in Avalonia of northern Nova Scotia: repeated partial melting of anhydrous lower crust in contrasting tectonic environments

    Science.gov (United States)

    Murphy, J. Brendan; Shellnutt, J. Gregory; Collins, William J.

    2018-03-01

    Avalonian rocks in northern mainland Nova Scotia are characterized by voluminous 640-600 Ma calc-alkalic to tholeiitic mafic to felsic magmas produced in a volcanic arc. However, after the cessation of arc activity, repeated episodes of felsic magmatism between ca. 580 Ma and 350 Ma are dominated by A-type geochemical characteristics. Sm-Nd isotopic data, combined with zircon saturation temperature estimates, indicate that these magmas were formed by high temperature (800-1050 °C) melting of the same anhydrous crustal source. Regional tectonic considerations indicate that A-type felsic magmatism was produced (1) at 580 Ma in a San Andreas-type strike slip setting, (2) at 495 Ma as Avalonia rifted off Gondwana, (3) at 465 and 455 in an ensialic island arc environment and (4) at 360-350 Ma during post-collisional, intra-continental strike-slip activity as Avalonia was translated dextrally along the Laurentian margin. These results attest to the importance of crustal source, rather than tectonic setting, in the generation of these A-type magmas and are an example of how additional insights are provided by comparing the geochemical and isotopic characteristics of igneous suites of different ages within the same terrane. They also suggest that the shallow crustal rocks in northern mainland Nova Scotia were not significantly detached from their lower crustal source between ca. 620 Ma and 350 Ma, a time interval that includes the separation of Avalonia from Gondwana, its drift and accretion to Laurentia as well as post-accretionary strike-slip displacement.

  6. WAVELET TRANSFORM ANALYSIS OF ELECTROMYOGRAPHY KUNG FU STRIKES DATA

    Directory of Open Access Journals (Sweden)

    Ana Carolina de Miranda Marzullo

    2009-11-01

    Full Text Available In martial arts and contact sports strikes are performed at near maximum speeds. For that reason, electromyography (EMG analysis of such movements is non-trivial. This paper has three main goals: firstly, to investigate the differences in the EMG activity of muscles during strikes performed with and without impacts; secondly, to assess the advantages of using Sum of Significant Power (SSP values instead of root mean square (rms values when analyzing EMG data; and lastly to introduce a new method of calculating median frequency values using wavelet transforms (WMDF. EMG data of the deltoid anterior (DA, triceps brachii (TB and brachioradialis (BR muscles were collected from eight Kung Fu practitioners during strikes performed with and without impacts. SSP results indicated significant higher muscle activity (p = 0.023 for the strikes with impact. WMDF results, on the other hand, indicated significant lower values (p = 0. 007 for the strikes with impact. SSP results presented higher sensitivity than rms to quantify important signal differences and, at the same time, presented lower inter-subject coefficient of variations. The result of increase in SSP values and decrease in WMDF may suggest better synchronization of motor units for the strikes with impact performed by the experienced Kung Fu practitioners

  7. Review of the Lightning Strike Incident at Launch Complex 37 on July 27, 1967, and Comparison to a Gemini Lightning Strike

    Science.gov (United States)

    Llewellyn, J. A.

    1967-01-01

    The Launch Complex 37 lightning strike of July 27, 1967, was reviewed and compared to a similar incident on the Gemini Program. Available data indicate little likelihood of damaging currents having been present in SA-204 Launch Vehicle or the ground equipment during the July 27th incident. Based on the results of subsystem and system testing after the strike, anticipated results of future testing, the six months elapsed time between the strike-and launch, and the fact that much of the critical airborne electrical/electronic equipment has been removed since the strike for other reasons, no new actions are considered necessary at this time in the Gemini case, significant failures occurred in both airborne and ground circuits. Due to the resultant semi, condlictor uncertainty, and the relatively' short time prior to planned launch, all critical airborne components containing semiconduetors were replaced, and a sophisticated data comparison task was implemented.

  8. InSAR observations of low slip rates on the major faults of western Tibet.

    Science.gov (United States)

    Wright, Tim J; Parsons, Barry; England, Philip C; Fielding, Eric J

    2004-07-09

    Two contrasting views of the active deformation of Asia dominate the debate about how continents deform: (i) The deformation is primarily localized on major faults separating crustal blocks or (ii) deformation is distributed throughout the continental lithosphere. In the first model, western Tibet is being extruded eastward between the major faults bounding the region. Surface displacement measurements across the western Tibetan plateau using satellite radar interferometry (InSAR) indicate that slip rates on the Karakoram and Altyn Tagh faults are lower than would be expected for the extrusion model and suggest a significant amount of internal deformation in Tibet.

  9. Slip length crossover on a graphene surface

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Zhi, E-mail: liangz3@rpi.edu [Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Keblinski, Pawel, E-mail: keplip@rpi.edu [Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-04-07

    Using equilibrium and non-equilibrium molecular dynamics simulations, we study the flow of argon fluid above the critical temperature in a planar nanochannel delimited by graphene walls. We observe that, as a function of pressure, the slip length first decreases due to the decreasing mean free path of gas molecules, reaches the minimum value when the pressure is close to the critical pressure, and then increases with further increase in pressure. We demonstrate that the slip length increase at high pressures is due to the fact that the viscosity of fluid increases much faster with pressure than the friction coefficient between the fluid and the graphene. This behavior is clearly exhibited in the case of graphene due to a very smooth potential landscape originating from a very high atomic density of graphene planes. By contrast, on surfaces with lower atomic density, such as an (100) Au surface, the slip length for high fluid pressures is essentially zero, regardless of the nature of interaction between fluid and the solid wall.

  10. Strike action by nurses in South Africa: A value clarification

    Directory of Open Access Journals (Sweden)

    Marie Muller

    2001-09-01

    Full Text Available The Labour Relations Act (South Africa, 1991 made provision for protected strike action by employees, subject to certain conditions, procedures and negotiated agreements. This led to the removal of the strike clause in the Nursing Act (South Africa, 1992. The labour rights of all citizens are entrenched in the Constitution of the country (South Africa, 1996. Participation in strike action by the nurse/ midwife, regardless of the legal requirements and specifications, does, however, pose an ethical question. It is therefore necessary to conduct a value clarification on strike action by nurses in South Africa. The purpose of this research is to explore and describe the perceived values of participants from an accessible population on this phenomenon. A qualitative, exploratory and descriptive research design was deployed. The perceived values of nurses on strike action were collected by means of an openended questionnaire/sketch. Over a period of three years a purposive and convenient sampling method was used, involving all the enrolled post basic nursing/midwifery students/ learners at a particular Nursing Education Institution. The justification of the sample was further enhanced by also collecting data on the participants’ age and provincial distribution location. Although a 63% sample realisation (of the accessible population was achieved, this represents only 1,5% of the registered nursing/midwifery population in the country. A descriptive analysis of the participants’ age and provincial distribution was undertaken, as well as a content analysis of their perceived values on strike action. The mean age of the participants was 48 years, which could be attributed to the fact that most of them were enrolled for a post-basic Diploma in Community Nursing Science. Most of the responses (52,7% were against strike action and 32,5% supported strike action by nurses as a constitutional and legal right. A fairly substantial number of participants (14

  11. Gait adaptations to awareness and experience of a slip when walking on a cross-slope.

    Science.gov (United States)

    Lawrence, Daniel; Domone, Sarah; Heller, Ben; Hendra, Timothy; Mawson, Susan; Wheat, Jon

    2015-10-01

    Falls that occur as a result of a slip are one of the leading causes of injuries, particularly in the elderly population. Previous studies have focused on slips that occur on a flat surface. Slips on a laterally sloping surface are important and may be related to different mechanisms of balance recovery. This type of slip might result in different gait adaptations to those previously described on a flat surface, but these adaptations have not been investigated. The aim of this study was to assess whether, when walking on a cross-slope, young adults adapted their gait when made aware of a potential slip, and having experienced a slip. Gait parameters were compared for three conditions--(1) Normal walking; (2) Walking after being made aware of a potential slip (participants were told that a slip may occur); (3) Walking after experiencing a slip (Participants had already experienced at least one slip induced using a soapy contaminant). Gait parameters were only analysed for trials in which there was no slippery contaminant present on the walkway. Stride length and walking velocity were significantly reduced, and stance duration was significantly greater in the awareness and experience conditions compared to normal walking, with no significant differences in any gait parameters between the awareness and experience conditions. In addition, 46.7% of the slip trials resulted in a fall. This is higher than reported for slips induced on a flat surface, suggesting slips on a cross-slope are more hazardous. This would help explain the more cautious gait patterns observed in both the awareness and experience conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Slow slip phenomena in Cascadia from 2007 and beyond: a review

    Science.gov (United States)

    Gomberg, Joan; ,

    2010-01-01

    Recent technological advances combined with more detailed analyses of seismologic and geodetic observations have fundamentally changed our understanding of the ways in which tectonic stresses arising from plate motions are accommodated by slip on faults. The traditional view that relative plate motions are accommodated by a simple cycle of stress accumulation and release on “locked” plate-boundary faults has been revolutionized by the serendipitous discovery and recognition of the significance of slow-slip phenomena, mostly in the deeper reaches of subduction zones. The Cascadia subduction zone, located in the Pacific Northwest of the conterminous United States and adjacent Canada, is an archetype of exploration and learning about slow-slip phenomena. These phenomena are manifest as geodetically observed aseismic transient deformations accompanied by a previously unrecognized class of seismic signals. Although secondary failure processes may be involved in generating the seismic signals, the primary origins of both aseismic and seismic phenomena appear to be episodic fault slip, probably facilitated by fluids, on a plate interface that is critically stressed or weakened. In Cascadia, this transient slip evolves more slowly and over more prolonged durations relative to the slip in earthquakes, and it occurs between the 30- and 40-km-depth contours of the plate interface where information was previously elusive. Although there is some underlying organization that relaxes nearly all the accrued plate-motion stresses along the entirety of Cascadia, we now infer that slow slip evolves in complex patterns indicative of propagating stress fronts. Our new understanding provides key constraints not only on the region where the slow slip originates, but also on the probable characteristics of future megathrust earthquakes in Cascadia. Herein, we review the most significant scientific issues and progress related to understanding slow-slip phenomena in Cascadia and

  13. A novel wireless piezoelectric tire sensor for the estimation of slip angle

    International Nuclear Information System (INIS)

    Erdogan, G; Alexander, L; Rajamani, R

    2010-01-01

    This paper introduces a simple approach for the analysis of tire deformation and proposes a new piezoelectric tire sensor for physically meaningful measurements of tire deformations. Tire deformation measurements in the contact patch can be used for the estimation of slip angle, tire forces, slip ratio and tire–road friction coefficient. The specific case of a wireless tire deformation sensor for the estimation of slip angle is taken up in this paper. A sensor in which lateral sidewall deformation can be decoupled from radial deformation is designed. The slope of the lateral deflection curve in the contact patch is used to calculate slip angle. A specially constructed tire test rig is used to experimentally evaluate the performance of the developed sensor. Results show that the developed sensor can accurately estimate slip angles up to values of 5°

  14. The Teacher Strike: School District Protection Procedures. A Manual for School District Officials on How to Handle a Teachers' Strike.

    Science.gov (United States)

    Igoe, Joseph A.; DiRocco, Anthony P.

    This booklet is designed to give practical and realistic advice to school district officials faced with the possibility of a teachers' strike. It is intended for use both by school district administrators and school board members. The booklet is organized into four sections that focus in turn on signs of a pending teachers' strike, union…

  15. A Theory of Material Spike Formation in Flow Separation

    Science.gov (United States)

    Serra, Mattia; Haller, George

    2017-11-01

    We develop a frame-invariant theory of material spike formation during flow separation over a no-slip boundary in two-dimensional flows with arbitrary time dependence. This theory identifies both fixed and moving separation, is effective also over short-time intervals, and admits a rigorous instantaneous limit. Our theory is based on topological properties of material lines, combining objectively stretching- and rotation-based kinematic quantities. The separation profile identified here serves as the theoretical backbone for the material spike from its birth to its fully developed shape, and remains hidden to existing approaches. Finally, our theory can be used to rigorously explain the perception of off-wall separation in unsteady flows, and more importantly, provide the conditions under which such a perception is justified. We illustrate our results in several examples including steady, time-periodic and unsteady analytic velocity fields with flat and curved boundaries, and an experimental dataset.

  16. ‘The Nairobi General Strike [1950]: from protest to insurgency’

    OpenAIRE

    Hyde, David

    2002-01-01

    The Nairobi General Strike [1950] was the culmination of Kenya’s post war strike wave and urban upheaval. An unprecedented upsurge occurred with the general strikes in Mombasa [1947] led by the African Workers Federation [A.W.F.] and in Nairobi by the East African Trades Union Congress [E.A.T.U.C.]. While this has been termed and treated as a city wide strike, there is enough evidence to suggest a movement that went some way beyond Nairobi. The extent of the cohesion and reciprocal impacts am...

  17. Dependence of dislocation structure on orientation and slip systems in highly oriented nanotwinned Cu

    DEFF Research Database (Denmark)

    Lu, Qiuhong; You, Zesheng; Huang, Xiaoxu

    2017-01-01

    slip Mode I and II are active with dominance of Mode II. In structures deformed at 45° dislocations from slip Modes I, II and III are identified, where Mode III dislocations consist of partial dislocations moving along the TBs and full dislocations inside the twin lamellae gliding on the slip planes...... parallel to the twin plane. The analysis of the dislocation structures illustrate the strong correlation between active slip systems and the dislocation structure and the strong effect of slip mode anisotropy on both the flow stress and strain hardening rate of nanotwinned Cu....

  18. Similar and Contrasting Response of Rifting and Transtension in the Gulf of California and Walker Lane to Preceding Arc Magmatism

    Science.gov (United States)

    Henry, C. D.; Faulds, J. E.

    2006-12-01

    The Gulf of California (GC) and Walker Lane (WL) have undergone strikingly similar development with strike- slip faulting following initial extension. They differ significantly in the amount of Pacific-North American plate motion taken up by each: essentially all relative motion in the GC and ~25% in the WL. In both areas, ancestral arc magmatism preceded and probably focused deformation, perhaps because heating and/or hydration weakened the lithosphere. However, differences in migration of the Rivera (RTJ) and Mendocino triple junctions (MTJ) related to differences in the orientation of plate boundaries determined how strike-slip faulting developed. Abrupt southward jumps in the RTJ led to abrupt cessation of magmatism over arc lengths of as much as 1000 km and initiation of east-northeast extension within the future GC. The best known jump was at ~13 Ma, but an earlier jump occurred at ~18 Ma. Arc magmatism has been best documented in Baja California, Sonora, and Nayarit, although Baja constituted the most-trenchward fringe of the ancestral arc. New and published data indicate that Sinaloa underwent a similar history of arc magmatism. The greatest volume of the arc immediately preceding RTJ jumps was probably in mainland Mexico. Arc magmatism shut off following these jumps, extension began in the future GC, and strike-slip faulting either followed or accompanied extension in the GC. In contrast, the MTJ migrated progressively northward. New and published data indicate magmatism generally shut off coincident with this retreat, but distinct nodes or zones of magmatism, presumably unrelated to subduction, persisted or initiated after arc activity ceased. We have suggested that the WL has grown progressively northward, following the retreating arc, and that the northern WL is its youngest part. However, the timing of initiation of strike-slip faulting in most of the WL is poorly known and controversial. Testing our hypothesis requires determining initiation and

  19. Local void and slip model used in BODYFIT-2PE

    International Nuclear Information System (INIS)

    Chen, B.C.J.; Chien, T.H.; Kim, J.H.; Lellouche, G.S.

    1983-01-01

    A local void and slip model has been proposed for a two-phase flow without the need of fitting any empirical parameters. This model is based on the assumption that all bubbles have reached their terminal rise velocities in the two-phase region. This simple model seems to provide reasonable calculational results when compared with the experimental data and other void and slip models. It provides a means to account for the void and slip of a two-phase flow on a local basis. This is particularly suitable for a fine mesh thermal-hydraulic computer program such as BODYFIT-2PE

  20. Numerical study of effects of accommodation coefficients on slip phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Jae; Kwon, Oh Joon [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    An unstructured mesh Navier-Stokes solver employing a Maxwell slip boundary condition was developed. The present flow solver was applied to the simulation of flows around an axisymmetric hollow cylinder in a Mach 10.4 free stream, known as Calspan-UB Research Center (CUBRC) Run 14 case, and the velocity slip and the temperature jump on the cylinder surface were investigated. The effect of tangential momentum and thermal accommodation coefficients used in the Maxwell condition was also investigated by adjusting their values. The results show that the reverse flow region is developed on the body surface due to the interaction between the shock and the boundary layer. Also, the shock impingement makes pressure high. The flow properties on the surface agree well with the experimental data, and the velocity slip and the temperature jump vary consistently with the local Knudsen number change. The accommodation coefficients affect the slip phenomena and the size of the flow region. The slip phenomena become larger when both tangential momentum and thermal accommodation coefficients are decreased. However, the range of the reverse flow region decreases when the momentum accommodation coefficient is decreased. The characteristics of the momentum and thermal accommodation coefficients also are overlapped when they are altered together.

  1. Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria

    Directory of Open Access Journals (Sweden)

    Briestenský Miloš

    2015-10-01

    Full Text Available The EU-TecNet monitoring network uses customized three-dimensional extensometers to record transient deformations across individual faults. This paper presents the first results from two newly established monitoring points in the Balkan Mountains in Bulgaria. The data from Saeva Dupka, recorded across an EEN-WWS striking fault, show sinistral strike-slip along the fault and subsidence of the southern block. Much of the subsidence occurred around the time of the distal MW = 5.6 Pernik Earthquake. An important transient deformation event, which began in autumn 2012, was reflected by significant compression and following extension, across the monitored fault. The data from Bacho Kiro, recorded across a NE–SW striking fault, show sinistral strike-slip along the fault and subsidence of the north-western block. The same important deformation event was reflected by changes in the strike-slip, dip-slip, and horizontal opening/closing trends. These results have been compared to data from other monitoring points in the Western Carpathians, External Dinarides, and Tian Shan. Many of the sites show evidence of simultaneous displacement anomalies and this observation is interpreted as a reflection of the plate-wide propagation of a tectonic pressure pulse towards the end of 2012.

  2. Solute softening and defect generation during prismatic slip in magnesium alloys

    Science.gov (United States)

    Yi, Peng; Cammarata, Robert C.; Falk, Michael L.

    2017-12-01

    Temperature and solute effects on prismatic slip of 〈a〉 dislocations in Mg are studied using molecular dynamics simulation. Prismatic slip is controlled by the low mobility screw dislocation. The screw dislocation glides on the prismatic plane through alternating cross-slip between the basal plane and the prismatic plane. In doing so, it exhibits a locking-unlocking mechanism at low temperatures and a more continuous wavy propagation at high temperatures. The dislocation dissociates into partials on the basal plane and the constriction formation of the partials is identified to be the rate-limiting process for unlocking. In addition, the diffusion of partials on the basal plane enables the formation of jogs and superjogs for prismatic slip, which lead to the generation of vacancies and dislocation loops. Solute softening in Mg alloys was observed in the presence of both Al and Y solute. The softening in prismatic slip is found to be due to solute pinning on the basal plane, instead of the relative energy change of the screw dislocation on the basal and prismatic planes, as has been hypothesized.

  3. Children on hunger strike: child abuse or legitimate protest?

    OpenAIRE

    Mok, A.; Nelson, E. A.; Murphy, J.; Hampson, A.; Hendriks, J. H.

    1996-01-01

    The issue of children on hunger strike (voluntary total fasting) has not been reported before. The World Medical Association Declaration of Tokyo 1975 and the Declaration of Malta 1991 (revised 1992) provide clinicians with guidelines for the management of adult patients on hunger strike but do not mention children. We report the management of 14 Vietnamese children, aged 1 to 12 years, who took part in a hunger strike at a refugee detention centre in Hong Kong.

  4. Expertise of using striking techniques for power stroke in badminton.

    Science.gov (United States)

    Zhu, Qin

    2013-10-01

    Two striking techniques (fast swing and angled striking) were examined to see if they allowed effective use of string tension for the power stroke in badminton. 12 participants (4 novices, 4 recreational, and 4 expert badminton players) were recorded by a fast-speed camera while striking a shuttlecock with racquets of 8 different string tensions. The peak speed of the shuttlecock, the racquet angle and the shuttlecock angle were analyzed. The results showed that expert players succeeded in using both striking techniques to overcome the constraint of string tension and produce a consistently superior stroke. Failure to use either striking technique resulted in inferior performance that was constrained by string tension. Expertise in badminton allows the necessary motor adjustments based on the affordance perception of the string tension.

  5. Geodetic evidence for en echelon dike emplacement and concurrent slow slip during the June 2007 intrusion and eruption at Kīlauea volcano, Hawaii

    Science.gov (United States)

    Montgomery-Brown, E. K.; Sinnett, D.K.; Poland, M.; Segall, P.; Orr, T.; Zebker, H.; Miklius, Asta

    2010-01-01

    A series of complex events at Kīlauea Volcano, Hawaii, 17 June to 19 June 2007, began with an intrusion in the upper east rift zone (ERZ) and culminated with a small eruption (1500 m3). Surface deformation due to the intrusion was recorded in unprecedented detail by Global Positioning System (GPS) and tilt networks as well as interferometric synthetic aperture radar (InSAR) data acquired by the ENVISAT and ALOS satellites. A joint nonlinear inversion of GPS, tilt, and InSAR data yields a deflationary source beneath the summit caldera and an ENE-striking uniform-opening dislocation with ~2 m opening, a dip of ∼80° to the south, and extending from the surface to ~2 km depth. This simple model reasonably fits the overall pattern of deformation but significantly misfits data near the western end of an inferred dike-like source. Three more complex dike models are tested that allow for distributed opening including (1) a dike that follows the surface trace of the active rift zone, (2) a dike that follows the symmetry axis of InSAR deformation, and (3) two en echelon dike segments beneath mapped surface cracks and newly formed steaming areas. The en echelon dike model best fits near-field GPS and tilt data. Maximum opening of 2.4 m occurred on the eastern segment beneath the eruptive vent. Although this model represents the best fit to the ERZ data, it still fails to explain data from a coastal tiltmeter and GPS sites on Kīlauea's southwestern flank. The southwest flank GPS sites and the coastal tiltmeter exhibit deformation consistent with observations of previous slow slip events beneath Kīlauea's south flank, but inconsistent with observations of previous intrusions. Slow slip events at Kīlauea and elsewhere are thought to occur in a transition zone between locked and stably sliding zones of a fault. An inversion including slip on a basal decollement improves fit to these data and suggests a maximum of ~15 cm of seaward fault motion, comparable to previous slow-slip

  6. Developing personal values: trainees' attitudes toward strikes by health care providers.

    Science.gov (United States)

    Li, Su-Ting T; Srinivasan, Malathi; Der-Martirosian, Claudia; Kravitz, Richard L; Wilkes, Michael S

    2011-05-01

    Worldwide, health care providers use strikes and job actions to influence policy. For health care providers, especially physicians, strikes create an ethical tension between an obligation to care for current patients (e.g., to provide care and avoid abandonment) and an obligation to better care for future patients by seeking system improvements (e.g., improvements in safety, to access, and in the composition and strength of the health care workforce). This tension is further intensified when the potential benefit of a strike involves professional self-interest and the potential risk involves patient harm or death. By definition, trainees are still forming their professional identities and values, including their opinions on fair wages, health policy, employee benefits, professionalism, and strikes. In this article, the authors explore these ethical tensions, beginning with a discussion of reactions to a potential 2005 nursing strike at the University of California, Davis, Medical Center. The authors then propose a conceptual model describing factors that may influence health care providers' decisions to strike (including personal ethics, personal agency, and strike-related context). In particular, the authors explore the relationship between training level and attitudes toward taking a job action, such as going on strike. Because trainees' attitudes toward strikes continue to evolve during training, the authors maintain that open discussion around the ethics of health care professionals' strikes and other methods of conflict resolution should be included in medical education to enhance professionalism and systems-based practice training. The authors include sample case vignettes to help initiate these important discussions. Copyright © by the Association of American medical Colleges.

  7. Ductility improvement by twinning and twin–slip interaction in a Mg-Y alloy

    International Nuclear Information System (INIS)

    Zhou, Na; Zhang, Zhenyan; Jin, Li; Dong, Jie; Chen, Bin; Ding, Wenjiang

    2014-01-01

    Highlights: • A high elongation of ∼33% was achieved for magnesium alloy through common extrusion. • Basal slip and extension twinning are the dominant deformation modes for the high ductility. • Non-basal slip, contraction twinning and twin-slip interaction also contribute to the ductility. - Abstract: An extruded Mg-3.0Y alloy with non-basal texture of 〈42 ¯ 2 ¯ 3〉 component was fabricated by common extrusion and exhibited a high elongation of ∼33%. The deformation modes and microstructure evolution of the extruded Mg-3.0Y alloy during the tensile test at room temperature were investigated to explore the reasons for the high ductility by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The results suggested that texture changed from 〈42 ¯ 2 ¯ 3〉 to 〈101 ¯ 0〉 component during the tensile deformation, which is attributed the slip and twinning activity. Basal slip and extension twinning are the dominant deformation modes for the high ductility. Meanwhile, the activation of non-basal slip, contraction twinning and twin–slip interaction also contributes to the good ductility of Mg-3.0Y alloy

  8. Friction, slip and structural inhomogeneity of the buried interface

    International Nuclear Information System (INIS)

    Dong, Y; Wu, J; Martini, A; Li, Q

    2011-01-01

    An atomistic model of metallic contacts using realistic interatomic potentials is used to study the connection between friction, slip and the structure of the buried interface. Incommensurability induced by misalignment and lattice mismatch is modeled with contact sizes that are large enough to observe superstructures formed by the relative orientations of the surfaces. The periodicity of the superstructures is quantitatively related to inhomogeneous shear stress distributions in the contact area, and a reduced order model is used to clarify the connection between friction and structural inhomogeneity. Finally, the movement of atoms is evaluated before, during and after slip in both aligned and misaligned contacts to understand how the interfacial structure affects the mechanisms of slip and the corresponding frictional behavior

  9. Effect of public transport strikes on air pollution levels in Barcelona (Spain).

    Science.gov (United States)

    Basagaña, Xavier; Triguero-Mas, Margarita; Agis, David; Pérez, Noemí; Reche, Cristina; Alastuey, Andrés; Querol, Xavier

    2018-01-01

    Public transport strikes can lead to an increase of the number of private vehicle trips, which in turn can increase air pollution levels. We aimed to estimate the change in air pollution concentrations during public transport strikes in the city of Barcelona (Spain). Data on strikes of the metro, train or bus systems were collected from government records (2005-2016). We collected daily concentrations of NOx; particulate matter with an aerodynamic diameter smaller than 10μm (PM10), 2.5μm (PM2.5), and 1μm (PM1); particle number concentration (N); black carbon (BC) and CO from research and official monitoring stations. We fitted linear regression models for each pollutant with the strike indicator as an independent variable, and models were adjusted for day of the week, month, year, and holiday periods. During the study period, there were 208days affected by a strike of the metro (28), train (106) or bus (91) systems. Half of the strikes were partial, most of them were single-day strikes, there was little overlap between strikes of the different transport systems, and all strikes had to comply with mandatory minimal services. When pooling all types of strikes, NOx and BC showed higher levels during strike days in comparison with non-strike days (increase between 4.1% and 7.7%, with higher increases for NO). The increases in these concentrations were more evident during full day and multiday metro strikes. In conclusion, alterations in public transport have consequences on air quality. This highlights the importance of public transport in reducing air pollution concentrations in cities. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Impact of lightning strikes on hospital functions.

    Science.gov (United States)

    Mortelmans, Luc J M; Van Springel, Gert L J; Van Boxstael, Sam; Herrijgers, Jan; Hoflacks, Stefaan

    2009-01-01

    Two regional hospitals were struck by lightning during a one-month period. The first hospital, which had 236 beds, suffered a direct strike to the building. This resulted in a direct spread of the power peak and temporary failure of the standard power supply. The principle problems, after restoring standard power supply, were with the fire alarm system and peripheral network connections in the digital radiology systems. No direct impact on the hardware could be found. Restarting the servers resolved all problems. The second hospital, which had 436 beds, had a lightning strike on the premises and mainly experienced problems due to induction. All affected installations had a cable connection from outside in one way or another. The power supplies never were endangered. The main problem was the failure of different communication systems (telephone, radio, intercom, fire alarm system). Also, the electronic entrance control went out. During the days after the lightening strike, multiple software problems became apparent, as well as failures of the network connections controlling the technical support systems. There are very few ways to prepare for induction problems. The use of fiber-optic networks can limit damage. To the knowledge of the authors, these are the first cases of lightning striking hospitals in medical literature.

  11. Seismic attribute detection of faults and fluid pathways within an active strike-slip shear zone: New insights from high-resolution 3D P-Cable™ seismic data along the Hosgri Fault, offshore California

    Science.gov (United States)

    Kluesner, Jared W.; Brothers, Daniel

    2016-01-01

    Poststack data conditioning and neural-network seismic attribute workflows are used to detect and visualize faulting and fluid migration pathways within a 13.7 km2 13.7 km2 3D P-Cable™ seismic volume located along the Hosgri Fault Zone offshore central California. The high-resolution 3D volume used in this study was collected in 2012 as part of Pacific Gas and Electric’s Central California Seismic Imaging Project. Three-dimensional seismic reflection data were acquired using a triple-plate boomer source (1.75 kJ) and a short-offset, 14-streamer, P-Cable system. The high-resolution seismic data were processed into a prestack time-migrated 3D volume and publically released in 2014. Postprocessing, we employed dip-steering (dip and azimuth) and structural filtering to enhance laterally continuous events and remove random noise and acquisition artifacts. In addition, the structural filtering was used to enhance laterally continuous edges, such as faults. Following data conditioning, neural-network based meta-attribute workflows were used to detect and visualize faults and probable fluid-migration pathways within the 3D seismic volume. The workflow used in this study clearly illustrates the utility of advanced attribute analysis applied to high-resolution 3D P-Cable data. For example, results from the fault attribute workflow reveal a network of splayed and convergent fault strands within an approximately 1.3 km wide shear zone that is characterized by distinctive sections of transpressional and transtensional dominance. Neural-network chimney attribute calculations indicate that fluids are concentrated along discrete faults in the transtensional zones, but appear to be more broadly distributed amongst fault bounded anticlines and structurally controlled traps in the transpressional zones. These results provide high-resolution, 3D constraints on the relationships between strike-slip fault mechanics, substrate deformation, and fluid migration along an active

  12. Stress transfer by the 1988-1989 M=5.3 and 5.4 Lake Elsman foreshocks to the Loma Prieta fault: Unclamping at the site of peak mainshock slip

    Science.gov (United States)

    Perfettini, H.; Stein, R.S.; Simpson, R.; Cocco, M.

    1999-01-01

    We study the stress transferred by the June 27, 1988, M=5.3 and August 8, 1989, M=5.4 Lake Elsman earthquakes, the largest events to strike within 15 km of the future Loma Prieta rupture zone during 74 years before the 1989 M=6.9 Loma Prieta earthquake. We find that the first Lake Elsman event brought the rupture plane of the second event 0.3-1.6 bars (0.03-0.16 MPa) closer to Coulomb failure but that the Lake Elsman events did not bring the future Loma Prieta hypocentral zone closer to failure. Instead, the Lake Elsman earthquakes are calculated to have reduced the normal stress on (or "undamped") the Loma Prieta rupture surface by 0.5-1.0 bar (0.05-0.10 MPa) at the site where the greatest slip subsequently occurred in the Loma Prieta earthquake. This association between the sites of peak unclamping and slip suggests that the Lake Elsman events did indeed influence the Loma Prieta rupture process. Unclamping the fault would have locally lowered the resistance to sliding. Such an effect could have been enhanced if the lowered normal stress permitted fluid infusion into the undamped part of the fault. Although less well recorded, the ML=5.0 1964 and ML=5.3 1967 Corralitos events struck within 10 km of the southwest end of the future Loma Prieta rupture. No similar relationship between the normal stress change and subsequent Loma Prieta slip is observed, although the high-slip patch southwest of the Loma Prieta epicenter corresponds roughly to the site of calculated Coulomb stress increase for a low coefficient of friction. The Lake Elsman-Loma Prieta result is similar to that for the 1987 M=6.2 Elmore Ranch and M=6.7 Superstition Hills earthquakes, suggesting that foreshocks might influence the distribution of mainshock slip rather than the site of mainshock nucleation. Copyright 1999 by the American Geophysical Union.

  13. Unscented Kalman Filter-Trained Neural Networks for Slip Model Prediction

    Science.gov (United States)

    Li, Zhencai; Wang, Yang; Liu, Zhen

    2016-01-01

    The purpose of this work is to investigate the accurate trajectory tracking control of a wheeled mobile robot (WMR) based on the slip model prediction. Generally, a nonholonomic WMR may increase the slippage risk, when traveling on outdoor unstructured terrain (such as longitudinal and lateral slippage of wheels). In order to control a WMR stably and accurately under the effect of slippage, an unscented Kalman filter and neural networks (NNs) are applied to estimate the slip model in real time. This method exploits the model approximating capabilities of nonlinear state–space NN, and the unscented Kalman filter is used to train NN’s weights online. The slip parameters can be estimated and used to predict the time series of deviation velocity, which can be used to compensate control inputs of a WMR. The results of numerical simulation show that the desired trajectory tracking control can be performed by predicting the nonlinear slip model. PMID:27467703

  14. SlipStream: automated provisioning and continuous deployment in the cloud

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Cloud technology is now everywhere. Beyond the hype, it provides a real opportunity to improve the engineering of software systems. Lately the DevOps movement has also gain momentum, which take an agile approach at bringing developers and system administrators closer together to better engineer software systems. In this context, this presentation focuses on new tools for exploiting cloud services (private and public) in order to create a continuous flow between software commits and fully deployed and configured software systems, automatically and on-demand. To illustrate this, we present SlipStream and StratusLab. SlipStream is a new product developed by SixSq, able to create virtual machines and orchestrate multi-machine deployments.  SlipStream started from an idea developed in the context of the ETICS project, led by CERN. StratusLab is an open-source IaaS distribution, able to create public and private clouds. This presentation will also describe a case study where SlipStream dep...

  15. The Effects of Obesity and Age on Balance Recovery After Slipping

    OpenAIRE

    Allin, Leigh Jouett

    2014-01-01

    Falls due to slipping are a serious occupational concern. Slipping is estimated to cause 40-50% of all fall-related injuries. In 2011, falls resulted in 22% of injuries requiring days away from work. Epidemiological data indicates that older and obese adults experience more falls than young, non-obese individuals. An increasingly heavier and older workforce may be exacerbating the problem of slip-induced falls in the workplace. The purpose of this study was to examine the effects of obesity a...

  16. On the micromechanics of slip events in sheared, fluid-saturated fault gouge

    Science.gov (United States)

    Dorostkar, Omid; Guyer, Robert A.; Johnson, Paul A.; Marone, Chris; Carmeliet, Jan

    2017-06-01

    We used a three-dimensional discrete element method coupled with computational fluid dynamics to study the poromechanical properties of dry and fluid-saturated granular fault gouge. The granular layer was sheared under dry conditions to establish a steady state condition of stick-slip dynamic failure, and then fluid was introduced to study its effect on subsequent failure events. The fluid-saturated case showed increased stick-slip recurrence time and larger slip events compared to the dry case. Particle motion induces fluid flow with local pressure variation, which in turn leads to high particle kinetic energy during slip due to increased drag forces from fluid on particles. The presence of fluid during the stick phase of loading promotes a more stable configuration evidenced by higher particle coordination number. Our coupled fluid-particle simulations provide grain-scale information that improves understanding of slip instabilities and illuminates details of phenomenological, macroscale observations.

  17. [Force-feeding of hunger-striking prisoners].

    Science.gov (United States)

    Glick, Shimon

    2014-09-01

    In contrast to the position of the World Medical Association and the Ethics Council of the Israel Medical Association, the author argues for forced-feeding of hunger-striking prisoners when their condition reaches a stage of danger of death or permanent injury. This position is based on the priority of human life over autonomy, and of a communitarian ethic. This position is supported by a District Court decision ordering the feeding of a hunger-striking prisoner, by a Supreme Court decision imposing surgery on a non-consenting prisoner, and in line with Israel's Patient's Right Law.

  18. Influence of plastic slip localization on grain boundary stress fields and microcrack nucleation

    International Nuclear Information System (INIS)

    Sauzay, Maxime; Vor, Kokleang

    2013-01-01

    Slip localization is widely observed in metallic polycrystals after tensile deformation, cyclic deformation (persistent slip bands) or pre-irradiation followed by tensile deformation (channels). Such strong deformation localized in thin slip bands induces local stress concentrations in the quasi-elastic matrix around, at the intersections between slip bands and grain boundaries where microcracks are often observed. Since the work of Stroh, such stress fields have been modeled using the dislocation pile-up theory which leads to stress singularities similar to the LEFM ones. The Griffith criterion has then been widely applied, leading usually to strong underestimations of the macroscopic stress for microcrack nucleation. In fact, slip band thickness is finite: 50-1000 nm depending on material, temperature and loading conditions. Then, many slip planes are plastically activated through the thickness. Stress fields have probably been overestimated using the pile-up theory which assumes that all dislocations are located on the same atomic plane. To evaluate more realistic stress fields, crystalline finite element (FE) computations are carried out using microstructure inputs (slip band aspect ratio and spacing). Slip bands (low critical resolved shear stress) are embedded in an elastic matrix. The following results are obtained concerning grain boundary normal stress fields: - strong influence of slip band thickness close to the slip band corner, which is not accounted for by the pile-up theory. But far away, the thickness has a negligible effect and the predicted stress fields are close to the one predicted by the pile-up theory, - analytical formulae are deduced from the numerous FE computation results which allows the prediction of surface/bulk slips as well as grain boundary stress fields. Slip band plasticity parameters, slip band length and thickness, Schmid factor and remote stress are taken into account. The dependence with respect to the various parameters can

  19. Slip experiment on a flat bottom cylindrical shell tank model; Hirazoko ento choso mokei no katsudo jikken

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, T.; Mentani, Y.; Komori, H.; Yoshihara, T. [Kawasaki Heavy Industries, Ltd., Kobe (Japan)

    1998-12-20

    Although large tank slip, as observed in Alaska in 1964, was not reported in the Hyogo Nanbu Earthquake, tank slip becomes a major concern in seismic engineering. In the case of a non-uplifting tank, ifs slip behavior can be accurately described by the simple analytical model which consists of a single degree of freedom on a potential sliding mass (SDOF slip model). Employing friction force during slip, the governing equations of the SDOF slip model are formulated as a discontinuous linear vibration system. From the analogies between the SDOF slip model and the tank, the physical quantities which correspond to the SDOF slip model are determined in accordance with the values which are specified by the seismic design code for the tank. Comparison of the experimental results of the model tank slip with the analytical results based on the SDOF slip model corroborates ifs applicability to the tank slip with sufficient accuracy. (author)

  20. Strike kinematics and performance in juvenile ball pythons (Python regius).

    Science.gov (United States)

    Ryerson, William G; Tan, Weimin

    2017-08-01

    The rapid strike of snakes has interested researchers for decades. Although most work has focused on the strike performance of vipers, recent work has shown that other snakes outside of the Viperidae can strike with the same velocities and accelerations. However, to date all of these examples focus on performance in adult snakes. Here, we use high-speed video to measure the strike kinematics and performance of 10 juvenile (pythons, Python regius. We find that juvenile P. regius strike at levels comparable to larger snakes, but with shorter durations and over shorter distances. We conclude that the juvenile P. regius maintain performance likely through manipulation of the axial musculature and accompanying elastic tissues, and that this is a first step to understanding ontogenetic changes in behavior and a potential avenue for understanding how captivity may also impact behavior. © 2017 Wiley Periodicals, Inc.