WorldWideScience

Sample records for striking faults numerous

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

    Indian Academy of Sciences (India)

    12

    Assemblage of strike-slip faults and tectonic. 1 extension and compression analysis: A case. 2 study of a Lower Permian commercial coal. 3 reservoir in China. 4. 5. Shuai Yina,*, Dawei Lvb, Zhonghu Wu c .... high-quality reservoirs, and tectonic action is a leading factor for oil and gas. 70 enrichment. Therefore, it is of great ...

  2. 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.

  3. 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.

  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. 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. 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.

  7. Continental strike slip fault zones in geologically complex lithosphere: the North Anatolian Fault, Turkey.

    Science.gov (United States)

    Cornwell, David; Thompson, David; Papaleo, Elvira; Rost, Sebastian; Houseman, Gregory; Kahraman, Metin; Turkelli, Niyazi; Teoman, Ugur; Altuncu Poyraz, Selda; Gulen, Levent; Utkucu, Murat

    2016-04-01

    As part of the multi-disciplinary Faultlab project, we present new detailed images in a geologically complex region where the crust and upper mantle is bisected by a major continental strike-slip fault system. Our study region samples the north Anatolian fault zone (NAFZ) near the epicentres of two large earthquakes that occurred in 1999 at Izmit (M7.5) and Düzce (M7.2) and where estimates of present day slip rate are 20-25 mm/yr. Using recordings of teleseismic earthquakes from a rectangular seismometer array spanning the NAFZ with 66 stations at a nominal inter-station spacing of 7 km and 7 additional stations further afield, we build a detailed 3-D image of structure and anisotropy using receiver functions, tomography and shear wave splitting and illuminate major changes in the architecture and properties of the upper crust, lower crust and upper mantle, both across and along the two branches of the NAFZ, at length scales of less than 20 km. We show that the northern NAFZ branch depth extent varies from the mid-crust to the upper mantle and it is likely to be less than 10 km wide. A high velocity lower crust and a region of crustal underthrusting appear to add strength to a heterogeneous crust and play a role in dictating the variation in faulting style and postseismic deformation. Sharp changes in lithospheric mantle velocity and anisotropy are constrained as the NAFZ is crossed, whereas crustal structure and anisotropy vary considerably both parallel and perpendicular to the faulting. We use our observations to test current models of the localisation of strike-slip deformation and develop new ideas to explain how narrow fault zones develop in extremely heterogeneous lithosphere.

  8. 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

  9. 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

  10. How seismicity impacts the evolution and branching of strike-slip faults

    Science.gov (United States)

    Preuss, S.; van Dinther, Y.; Ampuero, J. P.; Herrendoerfer, R.; Gerya, T.

    2017-12-01

    Strike-slip fault systems are capable of producing large earthquakes on both their main fault and on secondary and potentially unknown faults. A recent example is the 2016 Mw 7.8 Kaikōura earthquake that resulted in surface ruptures along at least 12 major crustal faults. Strike-slip faults are surrounded by inelastic off-fault deformation zones whose displacement accounts for up to 60% of the total displacement. Secondary faults in California accommodate up to 43% of the total fault slip rate of mapped faults taken from the SCEC catalog, while unknown faults arguably accommodate up to 30% of the long-term strain. To better understand these complexities and the long-term evolution of branching fault structures, we quantify the parameters influencing branching structure with a particular focus on the role of seismicity. We incorporate the relevant dynamics of both long-term fault evolution and short-term seismogenesis using the continuum visco-elasto-plastic tools of Seismo-Thermo-Mechanical (STM) modeling approach (van Dinther et al., 2013, Herrendörfer et al., in prep). Long-term fault evolution is governed by Drucker-Prager plasticity and plastic strain weakening of cohesion, while frictional weakening and rapid slip is governed by either strongly rate-dependent (RDF) or rate-and-state friction (RSF). We use a 2D, plane view, natural scale model setup (1200 km x 1000 km), which contains the end of a dextral mature strike-slip fault on one side. Episodic slip events on this pre-existing fault patch propagate into the undamaged host rock. As faults grow they develop a fan-like plastic strain envelope, whose width keeps growing with fault length and accumulated on-fault slip. We interpret this zone as a splay-fault network, which is typically seen ahead of propagating fault tips. We analyze the evolving faults in terms of dissipated strain energy GC, accumulated slip D and fault length L. Results show that a single event is capable of producing a several hundreds

  11. Strike slip faulting inferred from offsetting of drainages: Lower ...

    Indian Academy of Sciences (India)

    (a) Geological map of a part of lower Narmada valley showing disposition of active faults and structures (Agarwal. 1986). Red dotted box represents the area of figure 1(b). (b) Digital Elevation Model (DEM) of the part of Narmada valley showing various tectonic geomorphic features like fault scarp, palaeobank, linear valley ...

  12. Strike slip faulting inferred from offsetting of drainages: Lower ...

    Indian Academy of Sciences (India)

    The evolution of fault scarps, deformed rivers, marine terraces and the morphology of the moun- tain fronts have been studied for understanding neotectonic evolution of an area (Morisawa and. Hack 1985; Merritts and Hesterberg 1994; Keller and Printer 1996). Tricart (1974) discussed long- term effects of faulting and ...

  13. 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.

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

    Indian Academy of Sciences (India)

    Chinnery and Jovanovich (1972) extended the solution to a three-layer model. Savage and Prescott (1978) constructed a simple two-dimensional model of an earthquake cycle that takes place on a transform fault. Singh and Rani (1994) obtained an analytical solution for the problem of a long inclined strike- slip fault in an ...

  15. 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.

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

    Science.gov (United States)

    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

  17. 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 ...

  18. Dynamics of a strike-slip fault analog model : Effects of the tectonic loading rate

    Science.gov (United States)

    Caniven, Y.; Dominguez, S.; Soliva, R.; Cattin, R.; Peyret, M.; Chéry, J.; Romano, C.

    2013-12-01

    The average seismic cycle duration extends from hundred to a few thousands years but geodetic measurements and seismological data extend over less than one century. This short time observation scale renders difficult to constrain the role of key parameters such as fault friction and geometry, crust rheology, stress and strain rate that control the kinematics and mechanics of active faults. To solve this time scale issue, we have developed a new experimental set-up that reproduces scaled micro-earthquakes and several hundreds of seismic cycles along a strike-slip fault. The model is constituted by two polyurethane foam plates laterally in contact, lying on a basal silicone layer, which simulate the mechanical behaviour of an elastoplastic upper crust over a ductile lower crust, respectively. To simulate the boundary conditions of a strike-slip fault, a computerized motoreductor system moves the two compartments on an opposite sens at a constant low velocity (a few μm/s). The model scaling, deduces from analog material physical parameters, implies that 1 cm in the model represents 2-3 km in the nature and 1 s is equivalent to 5-15 years. Surface-horizontal strain field is quantified by sub-pixel correlation of digital camera pictures recorded every 16 μm of displacement. We record about 2000 horizontal-velocity field measurements for each experiment. The analysis of model-interseismic and coseismic surface displacements and their comparison to seismogenic natural faults demonstrate that our analog model reproduces correctly both near and far-field surface strains. To compare the experiments, we have developed several algorithms that allow studying the main spatial and temporal evolution of the physical parameters and surface deformation processes that characterise the seismic cycle (magnitudes, stress, strain, friction coefficients, interseismic locking depth, recurrence time, ...). We also performed surface-velocity field inversions to assess the spatial

  19. Influence of fault trend, fault bends, and fault convergence on shallow structure, geomorphology, and hazards, Hosgri strike-slip fault, offshore central California

    Science.gov (United States)

    Johnson, S. Y.; Watt, J. T.; Hartwell, S. R.

    2012-12-01

    We mapped a ~94-km-long portion of the right-lateral Hosgri Fault Zone from Point Sal to Piedras Blancas in offshore central California using high-resolution seismic reflection profiles, marine magnetic data, and multibeam bathymetry. The database includes 121 seismic profiles across the fault zone and is perhaps the most comprehensive reported survey of the shallow structure of an active strike-slip fault. These data document the location, length, and near-surface continuity of multiple fault strands, highlight fault-zone heterogeneity, and demonstrate the importance of fault trend, fault bends, and fault convergences in the development of shallow structure and tectonic geomorphology. The Hosgri Fault Zone is continuous through the study area passing through a broad arc in which fault trend changes from about 338° to 328° from south to north. The southern ~40 km of the fault zone in this area is more extensional, resulting in accommodation space that is filled by deltaic sediments of the Santa Maria River. The central ~24 km of the fault zone is characterized by oblique convergence of the Hosgri Fault Zone with the more northwest-trending Los Osos and Shoreline Faults. Convergence between these faults has resulted in the formation of local restraining and releasing fault bends, transpressive uplifts, and transtensional basins of varying size and morphology. We present a hypothesis that links development of a paired fault bend to indenting and bulging of the Hosgri Fault by a strong crustal block translated to the northwest along the Shoreline Fault. Two diverging Hosgri Fault strands bounding a central uplifted block characterize the northern ~30 km of the Hosgri Fault in this area. The eastern Hosgri strand passes through releasing and restraining bends; the releasing bend is the primary control on development of an elongate, asymmetric, "Lazy Z" sedimentary basin. The western strand of the Hosgri Fault Zone passes through a significant restraining bend and

  20. Multiple strike slip faults sets: A case study from the Dead Sea transform

    Science.gov (United States)

    Ron, Hagai; Nur, Amos; Eyal, Y.

    1990-01-01

    In many strike slip tectonic settings, large rotations of crust blocks about vertical axes have been inferred from paleomagnetic data. These blocks are bounded by sets of parallel faults which presumably accommodate the relative motion between the blocks as regional deformation progress. A mechanical model by Nur et al., (1986) suggests that rotations greater than phi sub c equals 25 to 45 degrees must be accommodated by more than one set of faults, with angle phi sub c between their direction; consequently the sum of the angles between sets must be roughly equal to the total tectonic material rotation. To test this model, the authors investigated the fault geometry and field relation of fault sets in the Mt. Hermon area in northern Israel, where paleomagnetic declination implies data 69 degrees plus or minus 13 degrees counter-clockwise block rotation. The statistical and field relation analysis of over 315 faults shows that the faulting is predominantly right lateral strike slip consisting of three distinct sets. The oldest set strikes 253 degrees, the second oldest set strikes 293 degrees and the youngest strikes 339 degrees. This last direction is consistent also with the current north-south direction of the maximum principle stress axis. The angle phi sub c between the first and second sets is 39 degrees and between the second and third sets 46 degrees, in good agreement with the phi sub c angle predicted from mechanical considerations. The sum of the two angles is 85 degrees, in good agreement with the 69 degrees plus or minus 13 degrees CCW paleomagnetically derived rotation. The results suggest specifically that the sequential development of multiple intersecting fault sets is responsible for the faulting in the Mt. Hermon area; and generally that the model of block rotation with multiple faults provides very good simple rules for analyzing very complex fault patterns.

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

    Indian Academy of Sciences (India)

    12

    and its effect on the productivity of the tight reservoirs. The study will not only guide. 95 the oil-gas ..... 5 Effect of tectonic extension and compression on coal reservoir productivity. 288. 5.1 Strike-slip compression and ..... staff of all the authors that cooperated in performing the analyses. We are also. 425 grateful to the ...

  2. Strike slip faulting inferred from offsetting of drainages: Lower ...

    Indian Academy of Sciences (India)

    The detailed analysis of landforms,drainages and geology of the area between the rivers Amaravati and Karjan was carried out in order to understand the tectonic history of the lower Narmada basin. Movement along the various faults in the area was studied on the basis of the drainage offsetting. Horizontal offsetting of ...

  3. Modeling the evolution of the lower crust with laboratory derived rheological laws under an intraplate strike slip fault

    Science.gov (United States)

    Zhang, X.; Sagiya, T.

    2015-12-01

    The earth's crust can be divided into the brittle upper crust and the ductile lower crust based on the deformation mechanism. Observations shows heterogeneities in the lower crust are associated with fault zones. One of the candidate mechanisms of strain concentration is shear heating in the lower crust, which is considered by theoretical studies for interplate faults [e.g. Thatcher & England 1998, Takeuchi & Fialko 2012]. On the other hand, almost no studies has been done for intraplate faults, which are generally much immature than interplate faults and characterized by their finite lengths and slow displacement rates. To understand the structural characteristics in the lower crust and its temporal evolution in a geological time scale, we conduct a 2-D numerical experiment on the intraplate strike slip fault. The lower crust is modeled as a 20km thick viscous layer overlain by rigid upper crust that has a steady relative motion across a vertical strike slip fault. Strain rate in the lower crust is assumed to be a sum of dislocation creep and diffusion creep components, each of which flows the experimental flow laws. The geothermal gradient is assumed to be 25K/km. We have tested different total velocity on the model. For intraplate fault, the total velocity is less than 1mm/yr, and for comparison, we use 30mm/yr for interplate faults. Results show that at a low slip rate condition, dislocation creep dominates in the shear zone near the intraplate fault's deeper extension while diffusion creep dominates outside the shear zone. This result is different from the case of interplate faults, where dislocation creep dominates the whole region. Because of the power law effect of dislocation creep, the effective viscosity in the shear zone under intraplate faults is much higher than that under the interplate fault, therefore, shear zone under intraplate faults will have a much higher viscosity and lower shear stress than the intraplate fault. Viscosity contract between

  4. Propagation of strike-slip faults across Holocene volcano-sedimentary deposits, Pasto, Colombia

    Science.gov (United States)

    Rovida, Andrea; Tibaldi, Alessandro

    2005-10-01

    This study contributes to the understanding of shear failure development on the basis of macroscopic field data collected in latest Pleistocene-Holocene pyroclastic and fluvio-lacustrine deposits in the Pasto Valley, SW Colombia. Here there is a pervasive system of microfaults and joints. Right-lateral strike-slip microfaults strike N065°, whereas left-lateral strike-slip microfaults strike N120°. Three main joint sets strike N, N065° and N020° in decreasing order of frequency. Stress computation gives a horizontal σ1 trending ˜N060° and a horizontal σ3 trending ˜N150°, consistent with earthquake focal mechanisms and stress inversion of main faults. Synthetic shears dominate resulting from nucleation of older cracks. In the basement cropping out northeast of Pasto, the NE- to ENE-striking Buesaco, Aranda and Pasto Faults show evidence of latest Pleistocene-Holocene right-lateral strike-slip motions. The structures in the Pasto Valley can be interpreted as a Mode III damage zone representing the up-dip propagation of the main faults across the young volcano-sedimentary deposits.

  5. Growth and linkage of the quaternary Ubrique Normal Fault Zone, Western Gibraltar Arc: role on the along-strike relief segmentation

    Science.gov (United States)

    Jiménez-Bonilla, Alejandro; Balanya, Juan Carlos; Exposito, Inmaculada; Diaz-Azpiroz, Manuel; Barcos, Leticia

    2015-04-01

    pattern seems to be related to other strike-slip fault systems developed to the E of the UNFZ. The structural revision together with updated kinematic data suggest that the Colmenar Fault is cut and downthrown by a younger normal fault zone, the UNFZ, which would have contributed to accommodate arc-parallel stretching until the Quaternary. This stretching provokes along-strike relief segmentation, being the UNFZ the main fault zone causing the final drop of the Subbetic ranges towards the SW within the Western Gibraltar Arc. Our results show displacement variations in each fault segment of the UNFZ, diminishing to their tips. This suggests fault segment linkage finally evolved to build the nearly continuous current fault zone. The development of current large through-going faults linked inside the UNFZ is similar to those ones simulated in some numerical modelling of rift systems [2]. Acknowledgements: RNM-415 and CGL-2013-46368-P [1]Peacock, D.C.P., Knipe, R.J., Sanderson, D.J., 2000. Glossary of normal faults. Journal Structural Geology, 22, 291-305. [2]Cowie, P.A., Gupta, S., Dawers, N.H., 2000. Implications of fault array evolution for synrift depocentre development: insights from a numerical fault growth model. Basin Research, 12, 241-261.

  6. Ductile shear zones beneath strike-slip faults: Implications for the thermomechanics of the San Andreas fault zone

    Science.gov (United States)

    Thatcher, W.; England, P.C.

    1998-01-01

    We have carried out two-dimensional (2-D) numerical experiments on the bulk flow of a layer of fluid that is driven in a strike-slip sense by constant velocities applied at its boundaries. The fluid has the (linearized) conventional rheology assumed to apply to lower crust/upper mantle rocks. The temperature dependence of the effective viscosity of the fluid and the shear heating that accompanies deformation have been incorporated into the calculations, as has thermal conduction in an overlying crustal layer. Two end-member boundary conditions have been considered, corresponding to a strong upper crust driving a weaker ductile substrate and a strong ductile layer driving a passive, weak crust. In many cases of practical interest, shear heating is concentrated close to the axial plane of the shear zone for either boundary condition. For these cases, the resulting steady state temperature field is well approximated by a cylindrical heat source embedded in a conductive half-space at a depth corresponding to the top of the fluid layer. This approximation, along with the application of a theoretical result for one-dimensional shear zones, permits us to obtain simple analytical approximations to the thermal effects of 2-D ductile shear zones for a range of assumed rheologies and crustal geotherms, making complex numerical calculations unnecessary. Results are compared with observable effects on heat flux near the San Andreas fault using constraints on the slip distribution across the entire fault system. Ductile shearing in the lower crust or upper mantle can explain the observed increase in surface heat flux southeast of the Mendocino triple junction and match the amplitude of the regional heat flux anomaly in the California Coast Ranges. Because ductile dissipation depends only weakly on slip rate, faults moving only a few millimeters per year can be important heat sources, and the superposition of effects of localized ductile shearing on both currently active and now

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Left-Lateral Strike-Slip Faulting in the East Alborz, NE Iran

    Science.gov (United States)

    Hollingsworth, J.; Walker, R.; Jackson, J.; Bolourchi, M. J.; Eshraghi, S. A.

    2006-12-01

    The East Alborz mountains of NE Iran are actively deforming as a result of Arabia-Eurasia collision. We combine observations of the geomorphology made using high resolution satellite, topographic and field data, with historical and recent seismicity to map major active faults in this poorly studied region. Deformation on the north side of the range occurs by range-normal shortening on the Khazar thrust fault, which separates Central Iran from the South Caspian. South of the range, deformation involves both left-lateral slip on the previously undocumented Shahrud fault system, which comprises several range-bounding fault segments, and shortening on (probably minor) thrust faults. Faulting south of the range is responsible for major historical earthquakes at Damghan (856AD) and Shahrud (1890). Deformation accommodated across the East Alborz is estimated from the difference in GPS velocities north and south of the range. South of the Alborz, northward GPS velocities across Central Iran decrease eastwards and the strike of the deforming belt changes to become more sub-parallel to the direction of South Caspian- Iran relative motion. This reduces the shortening component across the East Alborz, resulting in lower elevations between 54--57°E. West of 55.5°E, the more arc-normal shortening is achieved by partitioning of deformation onto the Khazar thrust (~1 mm/yr) and the Astaneh and Firuzkuh strike-slip faults (~3 mm/yr). East of 55.5°E, the Khazar fault ends and East Alborz deformation is accommodated primarily on the left-lateral Shahrud fault system, which may slip up to 3~mm/yr. Due to the long gap in seismicity along the eastern Shahrud fault system, the city of Jajarm (15,000 pop.) is considered at high risk from future earthquakes.

  12. Strike-slip faulting in the Inner California Borderlands, offshore Southern California.

    Science.gov (United States)

    Bormann, J. M.; Kent, G. M.; Driscoll, N. W.; Harding, A. J.; Sahakian, V. J.; Holmes, J. J.; Klotsko, S.; Kell, A. M.; Wesnousky, S. G.

    2015-12-01

    In the Inner California Borderlands (ICB), offshore of Southern California, modern dextral strike-slip faulting overprints a prominent system of basins and ridges formed during plate boundary reorganization 30-15 Ma. Geodetic data indicate faults in the ICB accommodate 6-8 mm/yr of Pacific-North American plate boundary deformation; however, the hazard posed by the ICB faults is poorly understood due to unknown fault geometry and loosely constrained slip rates. We present observations from high-resolution and reprocessed legacy 2D multichannel seismic (MCS) reflection datasets and multibeam bathymetry to constrain the modern fault architecture and tectonic evolution of the ICB. We use a sequence stratigraphy approach to identify discrete episodes of deformation in the MCS data and present the results of our mapping in a regional fault model that distinguishes active faults from relict structures. Significant differences exist between our model of modern ICB deformation and existing models. From east to west, the major active faults are the Newport-Inglewood/Rose Canyon, Palos Verdes, San Diego Trough, and San Clemente fault zones. Localized deformation on the continental slope along the San Mateo, San Onofre, and Carlsbad trends results from geometrical complexities in the dextral fault system. Undeformed early to mid-Pleistocene age sediments onlap and overlie deformation associated with the northern Coronado Bank fault (CBF) and the breakaway zone of the purported Oceanside Blind Thrust. Therefore, we interpret the northern CBF to be inactive, and slip rate estimates based on linkage with the Holocene active Palos Verdes fault are unwarranted. In the western ICB, the San Diego Trough fault (SDTF) and San Clemente fault have robust linear geomorphic expression, which suggests that these faults may accommodate a significant portion of modern ICB slip in a westward temporal migration of slip. The SDTF offsets young sediments between the US/Mexico border and the

  13. Relationships between along-fault heterogeneous normal stress and fault slip patterns during the seismic cycle: Insights from a strike-slip fault laboratory model

    Science.gov (United States)

    Caniven, Yannick; Dominguez, Stéphane; Soliva, Roger; Peyret, Michel; Cattin, Rodolphe; Maerten, Frantz

    2017-12-01

    We use a strike-slip fault analog model to study experimentally the role played by along-fault non-uniform and asymmetric applied normal stress on both coseismic slip and long-term fault behavior. Our model is based on a visco-elasto-plastic multi-layered rheology that allows to produce several hundreds of scaled analog microquakes and associated seismic cycles. Uniform or heterogeneous applied normal stress along the fault plane is imposed and maintained constant during the whole experiment durations. Our results suggest that coseismic slip patterns are strongly controlled by spatial normal stress variations and subsequent accumulated shear stress along fault strike. Major microquakes occur preferentially in zones of major shear stress asperities. Coseismic slip distributions exhibit a pattern similar to the along-fault applied normal stress distribution. The occurrence of isolated low to moderate microquakes where residual stresses persist around secondary stress asperities, indicates that stress conditions along the fault also control the whole variability of fault slip events. Moreover, when fault slip stability conditions are modulated by normal stress distribution, our experiments suggest that the along-fault stress heterogeneity influences the seismic cycle regularity and, consequently, long-term fault slip behavior. Uniform applied normal stress favors irregular seismic cycles and the occurrence of earthquakes clustering, whereas non-uniform normal stress with a single high amplitude stress asperity generates strong characteristic microquake events with stable return periods. Together our results strengthen the assumption that coseismic slip distribution and earthquake variability along an active fault may provide relevant information on long term tectonic stress and could thus improve seismic hazard assessment.

  14. Fault and fracture patterns around a strike-slip influenced salt wall

    Science.gov (United States)

    Alsop, G. I.; Weinberger, R.; Marco, S.; Levi, T.

    2018-01-01

    The trends of faults and fractures in overburden next to a salt diapir are generally considered to be either parallel to the salt margin to form concentric patterns, or at right angles to the salt contact to create an overall radial distribution around the diapir. However, these simple diapir-related patterns may become more complex if regional tectonics influences the siting and growth of a diapir. Using the Sedom salt wall in the Dead Sea Fault system as our case study, we examine the influence of regional strike-slip faulting on fracture patterns around a salt diapir. This type of influence is important in general as the distribution and orientation of fractures on all scales may influence permeability and hence control fluid and hydrocarbon flow. Fractures adjacent to the N-S trending salt wall contain fibrous gypsum veins and injected clastic dykes, attesting to high fluid pressures adjacent to the diapir. Next to the western flank of the salt wall, broad (∼1000 m) zones of upturn or 'drape folds' are associated with NW-SE striking conjugate extensional fractures within the overburden. Within 300 m of the salt contact, fracture patterns in map view display a progressive ∼30°-35° clockwise rotation with more NNW-SSE strikes immediately adjacent to the salt wall. While some extensional faults display growth geometries, indicating that they were syn-depositional and initiated prior to tilting of beds associated with drape folding, other fractures display increasing dips towards the salt, suggesting that they have formed during upturn of bedding near the diapir. These observations collectively suggest that many fractures developed to accommodate rotation of beds during drape folding. Extensional fractures in the overburden define a mean strike that is ∼45° anticlockwise (counter-clockwise) of the N-S trending salt wall, and are therefore consistent with sinistral transtension along the N-S trending Sedom Fault that underlies the salt wall. Our outcrop

  15. A preliminary study on surface ground deformation near shallow foundation induced by strike-slip faulting

    Science.gov (United States)

    Wong, Pei-Syuan; Lin, Ming-Lang

    2016-04-01

    According to investigation of recent earthquakes, ground deformation and surface rupture are used to map the influenced range of the active fault. The zones of horizontal and vertical surface displacements and different features of surface rupture are investigated in the field, for example, the Greendale Fault 2010, MW 7.1 Canterbury earthquake. The buildings near the fault rotated and displaced vertically and horizontally due to the ground deformation. Besides, the propagation of fault trace detoured them because of the higher rigidity. Consequently, it's necessary to explore the ground deformation and mechanism of the foundation induced by strike-slip faulting for the safety issue. Based on previous study from scaled analogue model of strike-slip faulting, the ground deformation is controlled by material properties, depth of soil, and boundary condition. On the condition controlled, the model shows the features of ground deformation in the field. This study presents results from shear box experiment on small-scale soft clay models subjected to strike-slip faulting and placed shallow foundations on it in a 1-g environment. The quantifiable data including sequence of surface rupture, topography and the position of foundation are recorded with increasing faulting. From the result of the experiment, first en echelon R shears appeared. The R shears rotated to a more parallel angle to the trace and cracks pulled apart along them with increasing displacements. Then the P shears crossed the basement fault in the opposite direction appears and linked R shears. Lastly the central shear was Y shears. On the other hand, the development of wider zones of rupture, higher rising surface and larger the crack area on surface developed, with deeper depth of soil. With the depth of 1 cm and half-box displacement 1.2 cm, en echelon R shears appeared and the surface above the fault trace elevated to 1.15 mm (Dv), causing a 1.16 cm-wide zone of ground-surface rupture and deformation

  16. Strike-Slip Fault Patterns on Europa: Obliquity or Polar Wander?

    Science.gov (United States)

    Rhoden, Alyssa Rose; Hurford, Terry A.; Manga, Michael

    2011-01-01

    Variations in diurnal tidal stress due to Europa's eccentric orbit have been considered as the driver of strike-slip motion along pre-existing faults, but obliquity and physical libration have not been taken into account. The first objective of this work is to examine the effects of obliquity on the predicted global pattern of fault slip directions based on a tidal-tectonic formation model. Our second objective is to test the hypothesis that incorporating obliquity can reconcile theory and observations without requiring polar wander, which was previously invoked to explain the mismatch found between the slip directions of 192 faults on Europa and the global pattern predicted using the eccentricity-only model. We compute predictions for individual, observed faults at their current latitude, longitude, and azimuth with four different tidal models: eccentricity only, eccentricity plus obliquity, eccentricity plus physical libration, and a combination of all three effects. We then determine whether longitude migration, presumably due to non-synchronous rotation, is indicated in observed faults by repeating the comparisons with and without obliquity, this time also allowing longitude translation. We find that a tidal model including an obliquity of 1.2?, along with longitude migration, can predict the slip directions of all observed features in the survey. However, all but four faults can be fit with only 1? of obliquity so the value we find may represent the maximum departure from a lower time-averaged obliquity value. Adding physical libration to the obliquity model improves the accuracy of predictions at the current locations of the faults, but fails to predict the slip directions of six faults and requires additional degrees of freedom. The obliquity model with longitude migration is therefore our preferred model. Although the polar wander interpretation cannot be ruled out from these results alone, the obliquity model accounts for all observations with a value

  17. A Three-Dimensional Numerical Investigation of San Andreas Fault Configuration Through the San Gorgonio Pass

    Science.gov (United States)

    Dair, L.; Cooke, M.

    2007-12-01

    The partitioning of deformation among strands of the San Andreas Fault through the San Gorgonio pass depends on fault geometry. We investigate three alternative three-dimensional configurations of the San Andreas Fault to explore the influence of fault geometry on uplift patterns and slip rates. One model has the commonly used vertical geometry for the system. Another uses the Southern California Earthquake Center Community Fault Model to include two north-dipping, discontinuous, alternative stands. We developed a third model that smoothly connects the north-dipping faults to adjacent segments. Regional transform loading is applied as slip at the distal edges of a deep detachment as well as along the distal portions of the primary fault segments. The model with vertical faults fails to produce uplift in the San Bernardino Mountains. Both of the north-dipping models produce significant uplift that may correspond to observations of recent uplift in the San Bernardino Mountains (Spotila et al, 1998). The vertical model has faster strike-slip rates while the north-dipping, discontinuous system has the slowest strike-slip rates. While the vertical model has the greatest net slip and more efficiently transmits deformation through the pass, the north-dipping fault configurations better match uplift patterns. We altered the continuous and north-dipping model to explore the effects of slip partitioning among the San Andreas and San Jacinto faults and secondary faults to the model. Debate continues about the slip partitioning between the Coachella Valley segment of the SAF and the San Jacinto fault. Our study suggests that slip portioning between the two faults has less of an effect on the slip rates and off fault deformation than fault geometry. The addition of secondary faults to the model significantly increases uplift in the northern San Bernardino Mountains. The senses of slip along secondary faults in the model are consistent with geologic observations. Continuing

  18. Inelastic off-fault response and three-dimensional dynamics of earthquake rupture on a strike-slip fault

    Science.gov (United States)

    Andrews, D.J.; Ma, Shuo

    2010-01-01

    Large dynamic stress off the fault incurs an inelastic response and energy loss, which contributes to the fracture energy, limiting the rupture and slip velocity. Using an explicit finite element method, we model three-dimensional dynamic ruptures on a vertical strike-slip fault in a homogeneous half-space. The material is subjected to a pressure-dependent Drucker-Prager yield criterion. Initial stresses in the medium increase linearly with depth. Our simulations show that the inelastic response is confined narrowly to the fault at depth. There the inelastic strain is induced by large dynamic stresses associated with the rupture front that overcome the effect of the high confining pressure. The inelastic zone increases in size as it nears the surface. For material with low cohesion (~5 MPa) the inelastic zone broadens dramatically near the surface, forming a "flowerlike" structure. The near-surface inelastic strain occurs in both the extensional and the compressional regimes of the fault, induced by seismic waves ahead of the rupture front under a low confining pressure. When cohesion is large (~10 MPa), the inelastic strain is significantly reduced near the surface and confined mostly to depth. Cohesion, however, affects the inelastic zone at depth less significantly. The induced shear microcracks show diverse orientations near the surface, owing to the low confining pressure, but exhibit mostly horizontal slip at depth. The inferred rupture-induced anisotropy at depth has the fast wave direction along the direction of the maximum compressive stress.

  19. Transpressional segment boundaries in strike-slip fault systems offshore southern California: Implications for fluid expulsion and cold seep habitats

    Science.gov (United States)

    Maloney, Jillian M.; Grupe, Benjamin M.; Pasulka, Alexis L.; Dawson, Katherine S.; Case, David H.; Frieder, Christina A.; Levin, Lisa A.; Driscoll, Neal W.

    2015-05-01

    The importance of tectonics and fluid flow in controlling cold seep habitats has long been appreciated at convergent margins but remains poorly understood in strike-slip systems. Here we present geophysical, geochemical, and biological data from an active methane seep offshore from Del Mar, California, in the inner California borderlands (ICB). The location of this seep appears controlled by localized transpression associated with a step in the San Diego Trough fault zone and provides an opportunity to examine the interplay between fluid expulsion and restraining step overs along strike-slip fault systems. These segment boundaries may have important controls on seep locations in the ICB and other margins characterized by strike-slip faulting (e.g., Greece, Sea of Marmara, and Caribbean). The strike-slip fault systems offshore southern California appear to have a limited distribution of seep sites compared to a wider distribution at convergent plate boundaries, which may influence seep habitat diversity and connectivity.

  20. 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.

  1. Lower Miocene coeval thrusting and strike-slip faulting in the Western Betics

    Science.gov (United States)

    Frasca, Gianluca; Gueydan, Frédéric; Brun, Jean-Pierre

    2015-04-01

    In the framework of the Africa-Europe convergence, the Mediterranean system presents a complex interaction between subduction rollback and upper subduction plate deformation since 30 Ma. The western end of the system shows an arcuate geometry across the Gibraltar arc, the Betico-Rifean belt, in which the relationship between slab dynamics and onshore tectonics is poorly constrained. The present study focuses on the Western Betics, which is characterized by two major thrusts: 1/ the Alboran Front limits the metamorphic domain (Alboran Domain) from the fold-and-thrust belts involving the Mesozoic cover of the Iberian margin (Subbetics Domain); 2/ the Alboran Internal Thrust allows the juxtaposition of a strongly attenuated lithosphere section, containing the large Ronda subcontinental mantle bodies, on top of crustal rocks. New structural data show that two major E-W strike-slip corridors controlled the deformation pattern of the Alboran Domain, in which E-W dextral strike-slip faults, N60° thrusts and N140° normal faults developed simultaneously during dextral strike-slip simple shear. The Alozaina piggy-back Basin, mainly formed by olistotromic deposits of Lower Miocene age, provides an age estimate for the continuous westward translation of the Alboran Domain, with reference to Iberia, that is accommodated mainly by an E-W lateral strike-slip ramp and a N60° frontal thrust ramp. In this context, a thrust sequence led to the piling up of thrust units in the Western Betics and to the crustal emplacement of the Ronda Peridotites bodies.

  2. 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

  3. 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.

  4. Analog modeling of strike-slip surface ruptures: Implications for Greendale Fault (New Zealand) mechanics and paleoseismology

    Science.gov (United States)

    Sasnett, P.; Quigley, M.; Cruden, A. R.; Boutelier, D. A.; Villamor, P.

    2013-12-01

    Analog modeling of strike-slip faulting provides insight into the development and behavior of surface ruptures with progressive slip, with relevance for understanding how coseismic displacements from fault ruptures are recorded in paleoseismic trenches. Patterns of surface deformation were investigated in analogue experiments using cohesive and non-cohesive granular materials above a vertical, planar, strike-slip basement fault. Surface deformation during the experiments was monitored by 3D PIV (Particle Imaging Velocimetry) and 2D time-lapse photography. Analysis of the experiments focused on fault zone morphology and development, as well as comparisons between the models and surface deformation observed along the Greendale Fault that resulted from the 2010 Darfield earthquake, New Zealand. Complex surface rupture patterns with similar characteristics to the Greendale Fault (en echelon fractures, Riedel shears, pop-up structures, etc.) were generated by a simple fault plane of uniform dip, slip, and frictional properties. The main controls on surface rupture morphology were found to be the properties and thickness of the overburden, the nature of the material surface, and the overall displacement of the underlying fault. Mapping the evolution of fracture patterns with progressive shear strain reveals that Riedel shears, striking 0-30° from the underlying basement fault, are more frequently reactivated during multiple displacement (earthquake) cycles, and are thus most likely to provide reliable paleoseismic records. This information will assist in the identification of suitable locations for paleoseismic trenches and in the interpretation of trench records from the Greendale Fault and other active, strike-slip faults in analogous geologic settings. The results also highlight the tendency of trenching studies of faults of this type to underestimate the number of and displacements on previous ruptures, which potentially leads to an underestimate of the magnitude

  5. Cenozoic structural inversion from transtension to transpression in Yingxiong Range, western Qaidam Basin: New insights into strike-slip superimposition controlled by Altyn Tagh and Eastern Kunlun Faults

    Science.gov (United States)

    Cheng, Xiang; Zhang, Daowei; Jolivet, Marc; Yu, Xiangjiang; Du, Wei; Liu, Runchao; Guo, Zhaojie

    2018-01-01

    A Cenozoic structural inversion event from transtension to transpression involving salt tectonics has been uncovered in the Yingxiong Range, the western Qaidam Basin. Seismic reflection data show that there are two common structural styles in the Yingxiong Range: (1) the positive flower structure; (2) the thrust-controlled fold at shallow depth and the positive inverted flower structure at deep levels, which are separated by a salt layer in the upper Xiaganchaigou Formation. The Yingxiong Range experienced a first stage of transtension in the Eocene, induced by the Altyn Tagh Fault, and a second stage of transpression from the early Miocene to present, jointly controlled by the Altyn Tagh and Eastern Kunlun Faults. The Eocene transtension produced numerous NW-striking right-stepping en-échelon transtensional normal faults or fractures in the Yingxiong Range. At the same time, evaporites and mudstone were deposited in the vicinity of these faults. In the early Miocene, the Eocene transtensional normal faults were reactivated in a reverse sense, and the thrust-controlled folds at shallow depth started to form simultaneously. With transpression enhanced in the late Cenozoic, positive flower structures directly formed in places without evaporites. The Cenozoic transtension to transpression inversion of the Yingxiong Range is the result of strike-slip superimposition controlled by the Altyn Tagh and Eastern Kunlun Faults in time and space.

  6. Strike-slip fault Kinematics and mechanics at the seismic cycle time-scale : Results from new analogue model experiments.

    Science.gov (United States)

    Caniven, Yannick; Dominguez, Stéphane; Soliva, Roger; Cattin, Rodolphe; Peyret, Michel; Chéry, Jean; Romano, Christian

    2013-04-01

    The average seismic cycle duration extends from hundred to a few thousands years but geodetic measurements, including trilateration, GPS, Insar and seismological data extend over less than one century. This short time observation scale renders difficult, then, to constrain the role of key parameters such as fault friction and geometry, crust rheology, stress and strain rate that control the kinematics and mechanics of active faults. To solve this time scale issue, we have developed a new experimental set-up that reproduces scaled micro-earthquakes and several hundreds of seismic cycles along a strike-slip fault. The model is constituted by two polyurethane foam plates laterally in contact, lying on a basal silicone layer, which simulate the mechanical behaviour of an elastoplastic upper crust over a ductile lower crust, respectively. To simulate the boundary conditions of a strike-slip fault, a computerized motoreductor system moves the two compartments on an opposite sens and at a constant very low velocity (a few µm/s). The model spatial and temporal scaling, deduces from analog material physical and mechanical parameters, implies that 1 cm in the model represents 2-3 km in the nature and 1 s is equivalent to 5-15 years. Surface-horizontal strain field is quantified by sub-pixel correlation of digital camera pictures recorded every 16 µm of displacement. For each experience about 2000 horizontal-velocity field measurements are recorded. The analysis of model-interseismic and coseismic surface displacements and their comparison to seismogenic natural faults demonstrate that our analog model reproduces correctly both near and far-field surface strains. To compare the experiences, we have developed several algorithms that allow studying the main spatial and temporal evolution of the physical parameters and surface deformation processes that characterise the seismic cycle (magnitudes, stress, strain, friction coefficients, interseismic locking depth, recurrence

  7. 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.

  8. A numerical model for bird strike on sidewall structure of an aircraft nose

    OpenAIRE

    Liu, Jun; Li, Yulong; Gao, Xiaosheng; Yu, Xiancheng

    2014-01-01

    In order to examine the potential of using the coupled smooth particles hydrodynamic (SPH) and finite element (FE) method to predict the dynamic responses of aircraft structures in bird strike events, bird-strike tests on the sidewall structure of an aircraft nose are carried out and numerically simulated. The bird is modeled with SPH and described by the Murnaghan equation of state, while the structure is modeled with finite elements. A coupled SPH–FE method is developed to simulate the bird...

  9. The impact of the Tsukiyoshi fault on the hydrogeological conditions in the Tono Area,Japan: A numerical modeling approach

    Science.gov (United States)

    Ndiweni, C.; Karasaki, K.; Doughty, C.; Botha, J. F.; Saegusa, H.

    2011-12-01

    Faults are commonly believed to act as either barriers to horizontal ground-water flow normal to the fault, conduits to horizontal flow parallel to the fault, or a combination of both. In addition, enhanced vertical permeability has also been observed as a common feature. We use numerical modeling to investigate the effects of vertical anisotropy of a dipping fault zone on the distribution of hydraulic head within and around the fault. The Tsukiyoshi Fault in the Tono region of Japan extends through the center of the assessment area and has an E-W strike. According to the results of borehole investigations, the fault has N80W strike, 70 degree dip, 10-30 m width and approximately 30 m vertical off-set. Model results show that for anisotropy ratios (A = kz/kx) of greater than 100, hydrostatic conditions are achieved within the fault zone, despite the existence of significant vertical flow rates. A hydraulic head difference of about 40 m across the fault is observed and confirmed by our model, suggesting that the fault acts as barrier to flow normal to it. We consider the pressure response to two shafts pumping in the upper parts of the fractured granitic formation near the fault. The response to pumping is monitored at two boreholes (DH-15 and DH-2) on the same side of the fault as the pumping shafts. The responses at the two boreholes are vertically invariant and highlight the effects of enhanced vertical permeability around the fault. This suggests that the fault controls the hydrology in this area. Particle tracking is used to investigate and demonstrate the effects of the fault on pathlines.

  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. Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

    Science.gov (United States)

    Prentice, Carol S.; Rizza, M.; Ritz, J.F.; Baucher, R.; Vassallo, R.; Mahan, S.

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans—particularly well preserved in the arid environment of the Gobi region—allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is∼1 mm yr–1 along the WIB and EIB segments and∼0.5 mm yr–1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at Mw 7.78–7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of∼2500

  12. Paleoearthquakes on the Anninghe and Zemuhe fault along the southeastern margin of the Tibetan Plateau and implications for fault rupture behavior at fault bends on strike-slip faults

    Science.gov (United States)

    Wang, Hu; Ran, Yongkang; Chen, Lichun; Li, Yanbao

    2017-11-01

    Fault bends can serve as fault segment boundaries and are used in seismic hazard assessment. Recent studies addressing whether rupture propagation would be arrested at such structural complexities have commonly focused on computational modeling. However, multi-cycle paleoseismic rupture observations through fault bends have seldom been reported. In this study, we used trenching and radiocarbon dating to reveal paleoseismic rupture histories on the southern segment of the Anninghe fault (ANHF) along the southeastern margin of the Tibetan Plateau to explore multi-cycle surface rupture behavior at an extensional fault bend (with an angle of about 30°) at Xichang between the ANHF and Zemuhe fault (ZMHF). Specifically, nine trenches were opened in a fault depression at Maoheshan site and five paleoseismic events were identified. These have been named E1 through E5 respectively corresponding to events at 1400-935 BCE, 420-875 CE, 830-1360 CE, 1295-1715 CE, and 1790 CE-Present. After comparison with the historical records of earthquakes around Xichang and previous paleoseismic results, we suggest that the five seismic events are constrained at: 1365 BCE-935 BCE, 814 CE, 950 CE- 1145 CE, 1536 CE and 1850 CE, respectively. The average recurrence interval of earthquakes along the southern segment of the ANHF is about 700-800 yr. Furthermore, the evidence indicates that surface-faulting events along the southern segment of the ANHF appear to be unevenly spaced in time. Moreover, based on comparisons of seismic events along the ANHF and ZMHF, we find that two fault segments simultaneous ruptured during the 814 CE and 1850 CE earthquakes, event E3 and the 1536 CE earthquake ruptured the ANHF but not rupture the ZMHF. We suggest that the Xichang fault bend is not a persistent fault boundary, indicating that extensional fault bends with an angle of about 30° may not effectively terminate seismic ruptures on strike-slip faults.

  13. 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.

  14. Structural evolution of the La Trocha fault zone: Oblique collision and strike-slip basins in the Cuban Orogen

    Science.gov (United States)

    Cruz-Orosa, Israel; Sã Bat, Francesc; Ramos, Emilio; Rivero, LluíS.; VáZquez-Taset, Yaniel M.

    2012-10-01

    The La Trocha fault zone acted as a major left-lateral transfer zone and is bounded by the La Trocha (LTF), Zaza-Tuinicú (ZTF), Cristales (CTF) and Taguasco (TGF) faults. These faults were consistent with the clockwise rotation of convergence and shortening in central Cuba. From the Paleocene to the Early Eocene (65-48 Ma), a SSW-NNE shortening produced transtension in the LTF and transpression in the ZTF. Subsequently, during the Middle Eocene (48-37 Ma), shortening shifted to a SW-NE direction, resulting in the normal component of the LTF and transpression in the ZTF and CTF. Since the Late Eocene (37 Ma), central Cuba has been welded to the North American Plate. The post-welding deformation gave rise to transtension of the LTF and TGF. This deformation is consistent with a WSW-ENE shortening and reflects activity in the transform boundary of the Cayman Trough. Both the normal and thrust displacements of these previous faults are corroborated by structural data whereas left-lateral displacement is deduced from the concordance between oblique collision and structural features. Plate-kinematics and the structural evolution of the La Trocha fault zone indicate that the related Central Basin is a strike-slip polygenetic basin and that the formation of this system (i.e., fault zone - strike-slip basin) was a consequence of the Paleogene oblique collision between the Caribbean Volcanic Arc and the Bahamas Borderland (North American plate).

  15. FD-TD numerical simulation of an entire lightning strike on the C160 aircraft

    Science.gov (United States)

    Alliot, J. C.; Grando, J.; Muller, J. D.; Ferrieres, X.

    1991-01-01

    Experimental transient electromagnetic field measurements were performed on a Transall C160 aircraft during in-flight lightning strikes. The data allow a test of the predictive capabilities of a three dimensional time domain finite difference code (ALICE) developed at ONERA in order to investigate lightning-aircraft interactions. Using a transfer function technique in the 3D code, it is shown that a bi-leader attached to an aircraft can be simulated by a linear model, and so the electromagnetic fields can be calculated anywhere on the vehicle. Comparison of experimental and numerical results were made for several lightning strikes. Skin current density and electromagnetic field distributions are discussed in detail.

  16. The Mechanics, Geometry and Distribution of Strike Slip Faults in a Fold and Thrust Belt, County Clare, Ireland

    Science.gov (United States)

    Nenna, F. A.; Aydin, A.

    2010-12-01

    Fundamental structures such as opening mode joints and veins, and closing mode pressure solution seams (PSSs) can form dense orthogonal arrays in collisional deformation belts and play important roles in the initiation and development of larger scale faults. We describe the deformation processes and the evolution of fault architecture using systematic documentation of field observations from arrays of strike-slip faults in the Carboniferous Ross Sandstone. This unit is exposed on the Loop Head Peninsula, County Clare, Ireland and was subject to compressive stresses associated with the Variscan orogeny at the end of the Carboniferous producing broad regional east-west trending folds and also tight low-amplitude folds cored by thrust faults. Near these faults, orthogonal sets of PSSs and joints/veins form contemporaneous arrays with pressure solution seams that are sub-parallel to the thrust fault traces and fold axes. A stress or material rotation during the Variscan Orogeny (or perhaps a major second stage of deformation either in late phase of the orogeny or post-orogeny) has lead to left-lateral shear of the PSSs evidenced by pressure solution splays and pull-aparts between their sheared segments, and right-lateral shear on the joints/veins evidenced by splay fractures. The splays of the sheared joints are in the same orientation of the joints in the pull-aparts of the sheared PSSs with which they merge. This indicates that the shearing of the joints/veins and the PSSs was likely to have occurred simultaneously under the same remote loading conditions. With increased shear, extensive splay fractures and pull-apart networks form weak damage zones through which strike-slip faults systems develop with slip of up to 2km. As a higher proportion of the shear is resolved on the joint system than that of the PSS system, the more prominent strike-slip faults are sub-parallel to or slightly inclined to the pre-existing joint/vein set and have a right-lateral sense of slip

  17. A numerical model for bird strike on sidewall structure of an aircraft nose

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2014-06-01

    Full Text Available In order to examine the potential of using the coupled smooth particles hydrodynamic (SPH and finite element (FE method to predict the dynamic responses of aircraft structures in bird strike events, bird-strike tests on the sidewall structure of an aircraft nose are carried out and numerically simulated. The bird is modeled with SPH and described by the Murnaghan equation of state, while the structure is modeled with finite elements. A coupled SPH–FE method is developed to simulate the bird-strike tests and a numerical model is established using a commercial software PAM-CRASH. The bird model shows no signs of instability and correctly modeled the break-up of the bird into particles. Finally the dynamic response such as strains in the skin is simulated and compared with test results, and the simulated deformation and fracture process of the sidewall structure is compared with images recorded by a high speed camera. Good agreement between the simulation results and test data indicates that the coupled SPH–FE method can provide a very powerful tool in predicting the dynamic responses of aircraft structures in events of bird strike.

  18. 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

  19. 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

  20. Along strike variation of active fault arrays and their effect on landscape morphology of the northwestern Himalaya

    Science.gov (United States)

    Nennewitz, Markus; Thiede, Rasmus; Bookhagen, Bodo

    2017-04-01

    The location and magnitude of the active deformation of the Himalaya has been debated for decades, but several aspects remain unknown. For instance, the spatial distribution of the deformation and the shortening that ultimately sustains Himalayan topography and the activity of major fault zones are not well constrained neither for the present day and nor for Holocene and Quarternary timescales. Because of these weakly constrained factors, many previous studies have assumed that the structural setting and the fault geometry of the Himalaya is continuous along strike and similar to fault geometries of central Nepal. Thus, the sub-surface structural information from central Nepal have been projected along strike, but have not been verified at other locations. In this study we use digital topographic analysis of the NW Himalaya. We obtained catchment-averaged, normalized steepness indexes of longitudinal river profiles with drainage basins ranging between 5 and 250km2 and analyzed the relative change in their spatial distribution both along and across strike. More specific, we analyzed the relative changes of basins located in the footwall and in the hanging wall of major fault zones. Under the assumption that along strike changes in the normalized steepness index are primarily controlled by the activity of thrust segments, we revealed new insights in the tectonic deformation and uplift pattern. Our results show three different segments along the northwest Himalaya, which are located, from east to west, in Garwhal, Chamba and Kashmir Himalaya. These have formed independent orogenic segments characterized by significant changes in their structural architecture and fault geometry. Moreover, their topographic changes indicate strong variations on fault displacement rates across first-order fault zones. With the help of along- and across-strike profiles, we were able to identify fault segments of pronounced fault activity across MFT, MBT, and the PT2 and identify the

  1. 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

  2. Along strike behavior of the Tizi n' Firest fault during the Lower Jurassic rifting (Central High Atlas Carbonate basin, Morocco)

    Science.gov (United States)

    Sarih, S.; Quiquerez, A.; Allemand, P.; Garcia, J. P.; El Hariri, K.

    2018-03-01

    The purpose of this study is to document the along-strike early syn-rift history of the Lower Jurassic Carbonate basin of the Central High Atlas (Morocco) by combining sedimentological observations and high-resolution biostratigraphy. Six sections, each from the Sinemurian to the Upper Pliensbachian, were investigated along a 75 km-long transect at the hanging wall of a major fault of the Lower Jurassic Basin (i.e. the Tizi n' Firest fault). Depositional geometries of the early syn-rift deposits were reconstructed from the correlation between eight main timelines dated by biochronological markers for a time span covering about 6 Ma. Depocentre migration was examined and accommodation rates were calculated at the sub-zone timescale to discuss the along-strike-fault behavior of the Lower Jurassic basin formation. The early stages of extension are marked by contrasted along-strike variations in depositional geometry thickness, depocentre migration and accommodation rates, leading to the growth of three independent sub-basins (i.e. western, central, and eastern), ranging in size from 30 to 50 km, and displaying three contrasted tectono-sedimentary histories. Our results suggest that, during the early rifting phase, tectonic activity was not a continuous and progressive process evolving towards a rift climax stage, but rather a series of acceleration periods that alternated with periods of much reduced activity. The length of active fault segments is estimated at about 15-20 km, with a lifespan of a few ammonite sub-zones (> 2-3 Ma).

  3. 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.

  4. Characteristics of the Late Quaternary right-lateral strike-slip movement of Bolokenu-Aqikekuduk fault in northern Tianshan Mountains, NW China

    Directory of Open Access Journals (Sweden)

    Jun Shen

    2011-10-01

    A typical strain partitioning style in the compression area has developed between the intermontane Bo-A fault and the piedmont thrust structures of Northern Tianshan Mountains, under the effect of oblique compression, as indicated by the piedmont thrust structure and the strike-slip fault in the mountains.

  5. The Iceland Plate Boundary Zone: Propagating Rifts, Migrating Transforms, and Rift-Parallel Strike-Slip Faults

    Science.gov (United States)

    Karson, J. A.

    2017-11-01

    Unlike most of the Mid-Atlantic Ridge, the North America/Eurasia plate boundary in Iceland lies above sea level where magmatic and tectonic processes can be directly investigated in subaerial exposures. Accordingly, geologic processes in Iceland have long been recognized as possible analogs for seafloor spreading in the submerged parts of the mid-ocean ridge system. Combining existing and new data from across Iceland provides an integrated view of this active, mostly subaerial plate boundary. The broad Iceland plate boundary zone includes segmented rift zones linked by transform fault zones. Rift propagation and transform fault migration away from the Iceland hotspot rearrange the plate boundary configuration resulting in widespread deformation of older crust and reactivation of spreading-related structures. Rift propagation results in block rotations that are accommodated by widespread, rift-parallel, strike-slip faulting. The geometry and kinematics of faulting in Iceland may have implications for spreading processes elsewhere on the mid-ocean ridge system where rift propagation and transform migration occur.

  6. 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.

  7. 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

  8. Laboratory and Numerical Observations of the Spectrum of Fault Slip Behaviors: Implications for Fault Zone Properties

    Science.gov (United States)

    Marone, C.

    2015-12-01

    Slow earthquakes, tectonic fault tremor and other modes of quasi-dynamic slip represent an important enigma. In the standard earthquake model, elastic energy is released catastrophically as the fault weakens and dynamic rupture expands at speeds measured in km/s. The spectral content of the resulting seismic waves is understood in terms of a source model based on elastodynamic rupture propagation. However, faults also fail in slow earthquakes and there is no such understanding of rupture dynamics, seismic spectra, or source scaling relations in these cases. The mechanics of slow earthquakes are poorly understood in part because there are few systematic laboratory observations that can be used to identify the underlying mechanics. Here, I summarize and discuss results from numerical models of slow slip using rate/state friction laws and recent lab studies showing slow slip and the full spectrum of stick-slip behaviors. Early lab studies saw slow slip during frictional sliding or in association with dehydration or ductile flow; however, they did not include systematic measurements that could be used to isolate the underlying mechanics. Numerical studies based on rate/state friction also document slow slip and chaotic forms of stick-slip, however they require special conditions including two state variable frictional behavior. Recent lab work sheds new light on slow earthquakes by showing: 1) that repetitive, slow stick-slip can occur if the fault friction-velocity relation becomes positive during slip acceleration, and 2) that slow slip and the full spectrum of fault slip modes can occur if loading stiffness k matches the fault zone critical rheologic stiffness kc given by the frictional weakening rate and the critical frictional distance. These data show that the key control parameter for stress drop, slip speed, and slip duration is the non dimensional stiffness k' = k/kc, with the spectrum of fast to slow slip mode occurring in a narrow range around k'=1. I

  9. Three-dimensional numerical modeling of the influence of faults on groundwater flow at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Cohen, Andrew J.B.

    1999-01-01

    Numerical simulations of groundwater flow at Yucca Mountain, Nevada are used to investigate how the faulted hydrogeologic structure influences groundwater flow from a proposed high-level nuclear waste repository. Simulations are performed using a 3-D model that has a unique grid block discretization to accurately represent the faulted geologic units, which have variable thicknesses and orientations. Irregular grid blocks enable explicit representation of these features. Each hydrogeologic layer is discretized into a single layer of irregular and dipping grid blocks, and faults are discretized such that they are laterally continuous and displacement varies along strike. In addition, the presence of altered fault zones is explicitly modeled, as appropriate. The model has 23 layers and 11 faults, and approximately 57,000 grid blocks and 200,000 grid block connections. In the past, field measurement of upward vertical head gradients and high water table temperatures near faults were interpreted as indicators of upwelling from a deep carbonate aquifer. Simulations show, however, that these features can be readily explained by the geometry of hydrogeologic layers, the variability of layer permeabilities and thermal conductivities, and by the presence of permeable fault zones or faults with displacement only. In addition, a moderate water table gradient can result from fault displacement or a laterally continuous low permeability fault zone, but not from a high permeability fault zone, as others postulated earlier. Large-scale macrodispersion results from the vertical and lateral diversion of flow near the contact of high and low permeability layers at faults, and from upward flow within high permeability fault zones. Conversely, large-scale channeling can occur due to groundwater flow into areas with minimal fault displacement. Contaminants originating at the water table can flow in a direction significantly different than that of the water table gradient, and isolated

  10. 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.

  11. The late Quaternary slip history of the North Anatolian Fault, Turkey: Implications for the spatial and temporal behaviour of large strike-slip fault belts

    Science.gov (United States)

    Zabcı, Cengiz; Akyüz, H. Serdar; Sançar, Taylan; Güneç Kıyak, Nafiye

    2015-04-01

    The study of the spatial and temporal behaviour of active faults by estimating the geologic and geodetic slip rates is critical not only for assessing the seismic potential of these tectonic structures, but also for understanding their geodynamics. Geodetic data can provide detailed spatial coverage but represent a short time interval of a single earthquake cycle, while geologic rates are derived as average values for multiple events at spatially limited sites. In the complex tectonic setting of the eastern Mediterranean, the westward extrusion of the Anatolian scholle is mainly accommodated by two major tectonic structures, the North Anatolian (NASZ) and the East Anatolian (EASZ) shear zones, respectively forming the northern and eastern boundaries. The rate of deformation all along the North Anatolian Fault (NAF) is spatially well documented mainly by GPS and InSAR based geodetic studies during the last two decades. Furthermore, the number of the morphochronology-based geologic slip rate studies significantly increased, covering the different sections of this large strike slip fault for various time intervals. In this study, we do not only compile all previous geologic slip rate estimates, but we also present data for three new and two revised sites from central to the most eastern parts of the NAF in order to understand the spatial and temporal behaviour of this important fault system. The integrated dataset of geologic studies were classified into two groups to represent the central to eastern sections (Model I) and the western part (Model II). The geographical diversion between two models is about at the 31° E longitude, where the NAF bifurcates into two branches from this point toward west into the Marmara Region. To test any secular variation in fault's slip history, we used the Monte Carlo approach of Gold and Cowgill (2011). After the removal of rates, which do not account the near fault deformation or the existing parallel/sub-parallel faults, the Model

  12. Turkish earthquakes reveal dynamics of fracturing along a major strike-slip fault zone

    Science.gov (United States)

    Çemen, Ibrahim; Gökten, Ergun; Varol, Baki; Kiliç, Recep; Özaksoy, Volkan; Erkmen, Cenk; Pinar, Ali

    During the last 5 months of 1999, northwestern Turkey experienced two major earthquakes along the North Anatolian Fault Zone (NAFZ). The first earthquake struck the country at 3:01 A.M. local time on August 17, and caused extensive damage in the towns of Yalova, Gölcük, Izmit, Adapazari, and Düzce (Figure 1). The second earthquake occurred at 6:57 P.M. local time on November 12 and caused damage mostly in Düzce and Kaynasli.The 7.4-Mw main shock of the August 17 Izmit earthquake was centered at 40.702°N, 29.987°E and originated at a depth of 17 km. The center was about 11 km southeast of Izmit, a major industrial town (Figure 1). The earthquake was a devastating natural disaster that claimed close to 20,000 lives and left more than 100,000 people homeless.

  13. 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.

  14. Role of the offshore Pedro Banks left-lateral strike-slip fault zone in the plate tectonic evolution of the northern Caribbean

    Science.gov (United States)

    Ott, B.; Mann, P.; Saunders, M.

    2013-12-01

    Previous workers, mainly mapping onland active faults on Caribbean islands, defined the northern Caribbean plate boundary zone as a 200-km-wide bounded by two active and parallel strike-slip faults: the Oriente fault along the northern edge of the Cayman trough with a GPS rate of 14 mm/yr, and and the Enriquillo-Plaintain Garden fault zone (EPGFZ) with a rate of 5-7 mm/yr. In this study we use 5,000 km of industry and academic data from the Nicaraguan Rise south and southwest of the EPGFZ in the maritime areas of Jamaica, Honduras, and Colombia to define an offshore, 700-km-long, active, left-lateral strike-slip fault in what has previously been considered the stable interior of the Caribbean plate as determined from plate-wide GPS studies. The fault was named by previous workers as the Pedro Banks fault zone because a 100-km-long segment of the fault forms an escarpment along the Pedro carbonate bank of the Nicaraguan Rise. Two fault segments of the PBFZ are defined: the 400-km-long eastern segment that exhibits large negative flower structures 10-50 km in width, with faults segments rupturing the sea floor as defined by high resolution 2D seismic data, and a 300-km-long western segment that is defined by a narrow zone of anomalous seismicity first observed by previous workers. The western end of the PBFZ terminates on a Quaternary rift structure, the San Andres rift, associated with Plio-Pleistocene volcanism and thickening trends indicating initial rifting in the Late Miocene. The southern end of the San Andreas rift terminates on the western Hess fault which also exhibits active strands consistent with left-lateral, strike-slip faults. The total length of the PBFZ-San Andres rift-Southern Hess escarpment fault is 1,200 km and traverses the entire western end of the Caribbean plate. Our interpretation is similar to previous models that have proposed the "stable" western Caribbean plate is broken by this fault whose rate of displacement is less than the threshold

  15. 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

  16. Dynamics of fault slip near the stability transition combining laboratory and numerical experiments

    Science.gov (United States)

    Mele Veedu, D.; Giorgetti, C.; Scuderi, M. M.; Barbot, S.; Marone, C.; Collettini, C.

    2017-12-01

    Frictional stability controls the seismogenic potential of faults. Laboratory (1) and theoretical (2) studies document and predict the conditions under which fault slip is seismic or aseismic. However, the full gamut of fault slip behavior near the stable/unstable boundary is still poorly known. Here, we combine insight from laboratory and numerical experiments to identify the wide spectrum of frictional instabilities around that transition, including slow-slip events, period-multiplying events, and chaos. We present a synoptic picture of the dynamics of fault slip in a bifurcation diagram obtained from a series of laboratory and numerical experiments. We compare the laboratory observations with spring-slider and finite-fault numerical models. In the laboratory, we vary the stiffness of the system by modulating the stress field around the experimental fault. In the numerical experiments, we vary the characteristic weakening distance to explore a range of critical nucleation sizes. Contrarily to previously found (3), complex fault dynamics can be obtained with a rate-and-state constitutive law with a single state variable. While the dynamics of fault slip is complicated on large faults by the presence of morphological and rheological heterogeneities, the range of instabilities identified in the laboratory is reminiscent of the variety of slow and fast earthquakes found along subduction zones (4). The accord between laboratory data and theoretical models affords more realistic predictions of fault behavior at slow slip speeds. (1) Scuderi et al., (2016), (2) Ruina (1983), (3) Gu & Wong (1994), (4) Obara & Kato (2016)

  17. 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

  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. 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.

  20. 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.

  1. 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

  2. Which Fault Orientations Occur during Oblique Rifting? Combining Analog and Numerical 3d Models with Observations from the Gulf of Aden

    Science.gov (United States)

    Autin, J.; Brune, S.

    2013-12-01

    Oblique rift systems like the Gulf of Aden are intrinsically three-dimensional. In order to understand the evolution of these systems, one has to decode the fundamental mechanical similarities of oblique rifts. One way to accomplish this, is to strip away the complexity that is generated by inherited fault structures. In doing so, we assume a laterally homogeneous segment of Earth's lithosphere and ask how many different fault populations are generated during oblique extension inbetween initial deformation and final break-up. We combine results of an analog and a numerical model that feature a 3D segment of a layered lithosphere. In both cases, rift evolution is recorded quantitatively in terms of crustal fault geometries. For the numerical model, we adopt a novel post-processing method that allows to infer small-scale crustal fault orientation from the surface stress tensor. Both models involve an angle of 40 degrees between the rift normal and the extensional direction which allows comparison to the Gulf of Aden rift system. The resulting spatio-temporal fault pattern of our models shows three normal fault orientations: rift-parallel, extension-orthogonal, and intermediate, i.e. with a direction inbetween the two previous orientations. The rift evolution involves three distinct phases: (i) During the initial rift phase, wide-spread faulting with intermediate orientation occurs. (ii) Advanced lithospheric necking enables rift-parallel normal faulting at the rift flanks, while strike-slip faulting in the central part of the rift system indicates strain partitioning. (iii) During continental break-up, displacement-orthogonal as well as intermediate faults occur. We compare our results to the structural evolution of the Eastern Gulf of Aden. External parts of the rift exhibit intermediate and displacement-orthogonal faults while rift-parallel faults are present at the rift borders. The ocean-continent transition mainly features intermediate and displacement

  3. 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

  4. Vertical-axis rotations and deformation along the active strike-slip El Tigre Fault (Precordillera of San Juan, Argentina) assessed through palaeomagnetism and anisotropy of magnetic susceptibility

    Science.gov (United States)

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

    2017-03-01

    Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault (Central-Western Precordillera of the San Juan Province, Argentina) demonstrate broad cumulative deformation up to 450 m from the fault trace and reveal clockwise and anticlockwise vertical-axis rotations of variable magnitude. This deformation has affected in different amounts Miocene to late Pleistocene samples and indicates a complex kinematic pattern. Several inherited linear structures in the shear zone that are oblique to the El Tigre Fault may have acted as block boundary faults. Displacement along these faults may have resulted in a complex pattern of rotations. The maximum magnitude of rotation is a function of the age of the sediments sampled, with largest values corresponding to middle Miocene-lower Pliocene deposits and minimum values obtained from late Pleistocene deposits. The kinematic study is complemented by low-field anisotropy of magnetic susceptibility data to show that the local strain regime suggests a N-S stretching direction, subparallel to the strike of the main fault.

  5. Mechanics of evenly spaced strike-slip faults and its implications for the formation of tiger-stripe fractures on Saturn's moon Enceladus

    Science.gov (United States)

    Yin, An; Zuza, Andrew V.; Pappalardo, Robert T.

    2016-03-01

    We present the first mechanical analysis based on realistic rheology and boundary conditions on the formation of evenly spaced strike-slip faults. Two quantitative models employing the stress-shadow concept, widely used for explaining extensional-joint spacing, are proposed in this study: (1) an empirically based stress-rise-function model that simulates the brittle-deformation process during the formation of evenly spaced parallel strike-slip faults, and (2) an elastic plate model that relates fault spacing to the thickness of the fault-hosting elastic medium. When applying the models for the initiation and development of the tiger-stripe fractures (TSF) in the South Polar Terrain (SPT) of Enceladus, the mutually consistent solutions of the two models, as constrained by the mean spacing of the TSF at ∼35 km, requires that the brittle ice-shell thickness be ∼30 km, the elastic thickness be ∼0.7 km, and the cohesive strength of the SPT ice shell be ∼30 kPa. However, if the brittle and elastic models are decoupled and if the ice-shell cohesive strength is on the order of ∼1 MPa, the brittle ice shell would be on the order of ∼10 km.

  6. Work Optimization Predicts Accretionary Faulting: An Integration of Physical and Numerical Experiments

    Science.gov (United States)

    McBeck, Jessica A.; Cooke, Michele L.; Herbert, Justin W.; Maillot, Bertrand; Souloumiac, Pauline

    2017-09-01

    We employ work optimization to predict the geometry of frontal thrusts at two stages of an evolving physical accretion experiment. Faults that produce the largest gains in efficiency, or change in external work per new fault area, ΔWext/ΔA, are considered most likely to develop. The predicted thrust geometry matches within 1 mm of the observed position and within a few degrees of the observed fault dip, for both the first forethrust and backthrust when the observed forethrust is active. The positions of the second backthrust and forethrust that produce >90% of the maximum ΔWext/ΔA also overlap the observed thrusts. The work optimal fault dips are within a few degrees of the fault dips that maximize the average Coulomb stress. Slip gradients along the detachment produce local elevated shear stresses and high strain energy density regions that promote thrust initiation near the detachment. The mechanical efficiency (Wext) of the system decreases at each of the two simulated stages of faulting and resembles the evolution of experimental force. The higher ΔWext/ΔA due to the development of the first pair relative to the second pair indicates that the development of new thrusts may lead to diminishing efficiency gains as the wedge evolves. The numerical estimates of work consumed by fault propagation overlap the range calculated from experimental force data and crustal faults. The integration of numerical and physical experiments provides a powerful approach that demonstrates the utility of work optimization to predict the development of faults.

  7. 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

  8. Offset of latest pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore central California

    Science.gov (United States)

    Johnson, Samuel Y.; Hartwell, Stephen R.; Dartnell, Peter

    2014-01-01

    The Hosgri fault is the southern part of the regional Hosgri–San Gregorio dextral strike‐slip fault system, which extends primarily in the offshore for about 400 km in central California. Between Morro Bay and San Simeon, high‐resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by an ∼265  m wide slope interpreted as the shoreface of a latest Pleistocene sand spit. This sand spit crossed an embayment and connected a western fault‐bounded bedrock peninsula and an eastern bedrock highland, a paleogeography resembling modern coastal geomorphology along the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6±0.9  mm/yr, considered a minimum rate for the Hosgri given the presence of an active western strand. This slip rate indicates that the Hosgri system takes up the largest share of the strike‐slip fault budget and is the most active strike‐slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high‐resolution bathymetry in characterization of active offshore faults.

  9. 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.

  10. A novel Lagrangian approach for the stable numerical simulation of fault and fracture mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Andrea; Ferronato, Massimiliano, E-mail: massimiliano.ferronato@unipd.it; Janna, Carlo; Teatini, Pietro

    2016-06-01

    The simulation of the mechanics of geological faults and fractures is of paramount importance in several applications, such as ensuring the safety of the underground storage of wastes and hydrocarbons or predicting the possible seismicity triggered by the production and injection of subsurface fluids. However, the stable numerical modeling of ground ruptures is still an open issue. The present work introduces a novel formulation based on the use of the Lagrange multipliers to prescribe the constraints on the contact surfaces. The variational formulation is modified in order to take into account the frictional work along the activated fault portion according to the principle of maximum plastic dissipation. The numerical model, developed in the framework of the Finite Element method, provides stable solutions with a fast convergence of the non-linear problem. The stabilizing properties of the proposed model are emphasized with the aid of a realistic numerical example dealing with the generation of ground fractures due to groundwater withdrawal in arid regions. - Highlights: • A numerical model is developed for the simulation of fault and fracture mechanics. • The model is implemented in the framework of the Finite Element method and with the aid of Lagrange multipliers. • The proposed formulation introduces a new contribution due to the frictional work on the portion of activated fault. • The resulting algorithm is highly non-linear as the portion of activated fault is itself unknown. • The numerical solution is validated against analytical results and proves to be stable also in realistic applications.

  11. From 2012 HAITI-SIS Survey: thick-skin versus thin-skin tectonics partitioned along offshore strike-slip Faults-Haïti

    Science.gov (United States)

    Ellouz, N.; Leroy, S. D.; Momplaisir, R.; Mercier de Lepinay, B.

    2013-12-01

    The characterization of the deformation along large strike-slip fault-systems like transpressive boundaries between N. Caribbean/N America is a challenging topic, which requires a multi-scale approach. Thanks to Haiti-sis new data, the precise description of the fault segmentation pattern, the sedimentogical distribution, the uplift/subsidence rates, the along-fault and intra-basin fluids circulations, allows to actualize the evolution of the deformation history up to present-day . All the co-seismic surface to near-surface events, have to be also identified in order to integrate geophysical solutions for the earthquake, within the present-day geological and structural pattern. These two approaches, ranging from geological to instantaneous time-scales have been used during multi-tools Haiti-Sis oceanographic survey, allowing to document and image these different aspects at a large scale. The complex strike-slip North Caribbean boundary registered significative stress partitioning. Oblique convergence is expressed by along-strike evolution; from rifted segments (Cayman Through) to transpressive ones (Haiti, Dominican Rep.), to subduction (Porto Rico). In the Haiti-Sis survey, we acquired new offshore data surrounding the active fault areas, in the Gonâve Bay, the Jamaica Channel and along Southern Peninsula. Mapping the sea-floor, and HR seismic acquisition were our main objectives, in order to characterize the fault and fold architecture, with a new delineation of active segments. Offshore piston cores, have been used as representative of the modern basin sedimentation, and to document the catastrophic events (earthquakes, massive flood or sudden destabilization of the platform ) represented by turbiditic or mass-flow sequences, with the objective to track the time recurrence of seismic events by dating some of these catastrophic sediment deposition. At surface, the other markers of the fault activity are linked with along-fault permeability and fluid circulation

  12. Numerical modelling of the mechanical and fluid flow properties of fault zones - Implications for fault seal analysis

    NARCIS (Netherlands)

    Heege, J.H. ter; Wassing, B.B.T.; Giger, S.B.; Clennell, M.B.

    2009-01-01

    Existing fault seal algorithms are based on fault zone composition and fault slip (e.g., shale gouge ratio), or on fault orientations within the contemporary stress field (e.g., slip tendency). In this study, we aim to develop improved fault seal algorithms that account for differences in fault zone

  13. 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.

  14. 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

  15. A new multilayered visco-elasto-plastic experimental model to study strike-slip fault seismic cycle

    NARCIS (Netherlands)

    Caniven, Y.; Dominguez, S.; Soliva, R.; Cattin, R.; Peyret, M.; Marchandon, M.; Romano, C.; Strak, V.

    2015-01-01

    Nowadays, technological advances in satellite imagery measurements as well as the development of dense geodetic and seismologic networks allow for a detailed analysis of surface deformation associated with active fault seismic cycle. However, the study of earthquake dynamics faces several limiting

  16. POTENTIAL EFFECTS OF FAULTS ON GROUNDWATER FLOW FOR THE YUCCA FLAT BASIN, NEVADA TEST SITE, NEVADA

    Science.gov (United States)

    Dickerson, R. P.; Fryer, W.

    2009-12-01

    The permeability changes resulting from finely comminuted material in fault cores and the fractured and brecciated rock in fault damage zones allows faults to channelize groundwater flow along the plane of the fault. The efficiency of faults as permeability structures depends on fault zone width, fault offset, depth at which the fault developed, type of faulted rock, extent of secondary mineralization, and fault orientation within current stress field. Studies of faulted volcanic rocks at Yucca Mountain, Nevada, indicate that fault zone width and brecciation increase with fault offset, that faulted welded tuff is more permeable than nonwelded or bedded tuff, and that non-hydrothermal secondary mineralization commonly diminishes fracture permeability. These results are applied to the groundwater conceptual flow model for Yucca Flat (YF) on the Nevada Test Site (NTS). Yucca Flat contains Tertiary volcanic rocks similar to thoise at Yucca Mountain deposited on Paleozoic carbonate rocks whose thickness is increased by local thrust-faults. The YF basin contains north-striking normal faults and is bordered by southwest-striking strike-slip faults to the south and east. Fault permeability values derived from faulted volcanic rocks at Yucca Mountain suggests that major normal faults in Yucca Flat potentially manifest permeability values along the fault plane equal to the highest values determined for volcanic aquifers. Numerous minor faults not assigned specific permeability values are assumed to imbue the basin with a hydraulic anisotropy favoring fault-parallel flow. In this scenario groundwater flows generally from north to south in the Yucca Flat basin, even as the head gradient is primarily towards the centrally located Yucca Fault, which acts as the main subsurface drainage feature within the basin. Studies show that the regional stress field has rotated clockwise such that southwest-striking strike-slip faults are currently under tension. In this scenario these

  17. Reconstructing the magnitude and timing of late Pleistocene and Holocene strike-slip events within the Marlborough Fault Zone, New Zealand

    Science.gov (United States)

    Rhodes, Ed; Dolan, James; Van Dissen, Russ; Langridge, Rob; Zinke, Rob; Hatem, Alex; McGuire, Chris; Brown, Nathan

    2017-04-01

    In most instances, information about the timing of pre-historic earthquake events comes from palaeoseismic trenches located within sediments that were deposited gradually and are close to the fault. Earthquake events are recognised by disturbed stratigraphy, and the timing provided by radiocarbon dating of organic materials that constrain the youngest disturbances for each event. In contrast, fault slip rates are typically derived from the dating of geomorphic features that are offset by one or more slip events. In this latter case, it is often hard to locate suitable organic material for dating these features which often comprise fluvial terraces or channels, and a variety of alternative chronological approaches has been taken including the use of terrestrial cosmogenic nuclides (TCNs; 10Be, 36Cl), U-series dating of carbonate overgrowths on pebbles, and/or luminescence dating of sediments. Using luminescence dating based on single grains of K-feldspar and a post-IR IRSL (Infra-Red Stimulated Luminescence) measurement protocol, we have been able to control the age of several offset terrace units from a number of major strike slip faults of the Marlborough Fault Zone, New Zealand. In the past, arguments concerning the selection of which geomorphic terrace feature to date have been presented, and typically a single age estimate, or small number of dates were used to constrain the derived slip rate. In the Marlborough region, we have sampled several locations characterised by multiple fluvial terraces dating from the late Glacial period (c. 16,000 years ago) through the Holocene. By using a high sampling density involving multiple age estimates within each terrace, dating each one of the terraces, and applying a Bayesian statistical approach to constrain the age of deposition and incision events, we are able to approach a situation where we can derive slip-per-event data and event timing from the same dataset. This can overcome problems of relating observed slip

  18. A Numerical Hydro-Chemo-Mechanical Model for Fault Activation under Reactive Fluid Flow

    Science.gov (United States)

    Pouya, A.; Tounsi, H.; Rohmer, J.

    2015-12-01

    The migration of CO2-rich fluid in fractured rock masses can cause processes such as mineral dissolution and precipitation, chemically induced weakening, which can affect the long-term mechanical and transport properties of the rock mass as well as the stability of fault systems. Some numerical approaches are already available in the literature for modelling the dissolution/precipitation phenomena in fractures (e.g. Yasuhara & Elsworth 2007) as well as subcritical crack propagation (e.g. Park et al. 2007). Generally, the dissolution is supposed to increase the rock porosity and, in this way, decrease the rock strength. Some experimental data are available for the variation of rock strength and stiffness parameters with the porosity and so as a consequence of dissolution process (Bemer et al. 2004). Also the effect of chemical processes on the mechanical stability has been studied and modelled numerically in the framework of continuum materials and the context, in particular, of weathering in underground galleries (Ghabezloo & Pouya 2006). In the context of fault systems, a complete numerical modelling of the stability evolution with the flow of a reactive fluid has not yet been done. In this paper we present a simplified, but complete, set of equations for a whole system of coupled hydro-chemo-mechanical process of reactive fluid flow inside a fault. These equations have been implemented in Porofis, a FEM numerical code specially conceived for HCM processes in porous fractured media. We show how this numerical method allows to model the coupled HCM processes in the fault and the evolution of the mechanical stability in presence of in situ stresses and reactive fluid flow.

  19. Numerical model of the glacially-induced intraplate earthquakes and faults formation

    Science.gov (United States)

    Petrunin, Alexey; Schmeling, Harro

    2016-04-01

    According to the plate tectonics, main earthquakes are caused by moving lithospheric plates and are located mainly at plate boundaries. However, some of significant seismic events may be located far away from these active areas. The nature of the intraplate earthquakes remains unclear. It is assumed, that the triggering of seismicity in the eastern Canada and northern Europe might be a result of the glacier retreat during a glacial-interglacial cycle (GIC). Previous numerical models show that the impact of the glacial loading and following isostatic adjustment is able to trigger seismicity in pre-existing faults, especially during deglaciation stage. However this models do not explain strong glaciation-induced historical earthquakes (M5-M7). Moreover, numerous studies report connection of the location and age of major faults in the regions undergone by glaciation during last glacial maximum with the glacier dynamics. This probably imply that the GIC might be a reason for the fault system formation. Our numerical model provides analysis of the strain-stress evolution during the GIC using the finite volume approach realised in the numerical code Lapex 2.5D which is able to operate with large strains and visco-elasto-plastic rheology. To simulate self-organizing faults, the damage rheology model is implemented within the code that makes possible not only visualize faulting but also estimate energy release during the seismic cycle. The modeling domain includes two-layered crust, lithospheric mantle and the asthenosphere that makes possible simulating elasto-plastic response of the lithosphere to the glaciation-induced loading (unloading) and viscous isostatic adjustment. We have considered three scenarios for the model: horizontal extension, compression and fixed boundary conditions. Modeling results generally confirm suppressing seismic activity during glaciation phases whereas retreat of a glacier triggers earthquakes for several thousand years. Tip of the glacier

  20. Investigating the possible effects of salt in the fault zones on rates of seismicity - insights from analogue and numerical modeling

    Science.gov (United States)

    Urai, Janos; Kettermann, Michael; Abe, Steffen

    2017-04-01

    The presence of salt in dilatant normal faults may have a strong influence on fault mechanics and related seismicity. However, we lack a detailed understanding of these processes. This study is based on the geological setting of the Groningen area. During tectonic faulting in the Groningen area, rock salt may have flown downwards into dilatant faults, which thus may contain lenses of rock salt at present. Because of its viscous properties, the presence of salt lenses in a fault may introduce a strain-rate dependency to the faulting and affect the distribution of magnitudes of seismic events. We present a "proof of concept" showing that the above processes can be investigated using a combination of analogue and numerical modeling. Full scaling and discussion of the importance of these processes to induced seismicity in Groningen require further, more detailed study. The analogue experiments are based on a simplified stratigraphy of the Groningen area, where it is generally thought that most of the Rotliegend faulting has taken place in the Jurassic, after deposition of the Zechstein. This is interpreted to mean that at the time of faulting the sulphates were brittle anhydrite. If these layers were sufficiently brittle to fault in a dilatant fashion, rock salt could flow downwards into the dilatant fractures. To test this hypothesis, we use sandbox experiments where we combine cohesive powder as analog for brittle anhydrites and carbonates with viscous salt analogs to explore the developing fault geometry and the resulting distribution of salt in the faults. In the numerical models we investigate the stick-slip behavior of fault zones containing ductile material using the Discrete Element Method (DEM). Results show that the DEM approach is in principle suitable for the modeling of the seismicity of faults containing salt: the stick-slip motion of the fault becomes dependent on shear loading rate with a modification of the frequency magnitude distribution of the

  1. Analysis of Fault Spacing in Thrust-Belt Wedges Using Numerical Modeling

    Science.gov (United States)

    Regensburger, P. V.; Ito, G.

    2017-12-01

    Numerical modeling is invaluable in studying the mechanical processes governing the evolution of geologic features such as thrust-belt wedges. The mechanisms controlling thrust fault spacing in wedges is not well understood. Our numerical model treats the thrust belt as a visco-elastic-plastic continuum and uses a finite-difference, marker-in-cell method to solve for conservation of mass and momentum. From these conservation laws, stress is calculated and Byerlee's law is used to determine the shear stress required for a fault to form. Each model consists of a layer of crust, initially 3-km-thick, carried on top of a basal décollement, which moves at a constant speed towards a rigid backstop. A series of models were run with varied material properties, focusing on the angle of basal friction at the décollement, the angle of friction within the crust, and the cohesion of the crust. We investigate how these properties affected the spacing between thrusts that have the most time-integrated history of slip and therefore have the greatest effect on the large-scale undulations in surface topography. The surface position of these faults, which extend through most of the crustal layer, are identifiable as local maxima in positive curvature of surface topography. Tracking the temporal evolution of faults, we find that thrust blocks are widest when they first form at the front of the wedge and then they tend to contract over time as more crustal material is carried to the wedge. Within each model, thrust blocks form with similar initial widths, but individual thrust blocks develop differently and may approach an asymptotic width over time. The median of thrust block widths across the whole wedge tends to decrease with time. Median fault spacing shows a positive correlation with both wedge cohesion and internal friction. In contrast, median fault spacing exhibits a negative correlation at small angles of basal friction (laws that can be used to predict fault spacing in

  2. Ring-fault activity at subsiding calderas studied from analogue experiments and numerical modeling

    Science.gov (United States)

    Liu, Y. K.; Ruch, J.; Vasyura-Bathke, H.; Jonsson, S.

    2017-12-01

    Several subsiding calderas, such as the ones in the Galápagos archipelago and the Axial seamount in the Pacific Ocean have shown a complex but similar ground deformation pattern, composed of a broad deflation signal affecting the entire volcanic edifice and of a localized subsidence signal focused within the caldera. However, it is still debated how deep processes at subsiding calderas, including magmatic pressure changes, source locations and ring-faulting, relate to this observed surface deformation pattern. We combine analogue sandbox experiments with numerical modeling to study processes involved from initial subsidence to later collapse of calderas. The sandbox apparatus is composed of a motor driven subsiding half-piston connected to the bottom of a glass box. During the experiments the observation is done by five digital cameras photographing from various perspectives. We use Photoscan, a photogrammetry software and PIVLab, a time-resolved digital image correlation tool, to retrieve time-series of digital elevation models and velocity fields from acquired photographs. This setup allows tracking the processes acting both at depth and at the surface, and to assess their relative importance as the subsidence evolves to a collapse. We also use the Boundary Element Method to build a numerical model of the experiment setup, which comprises contracting sill-like source in interaction with a ring-fault in elastic half-space. We then compare our results from these two approaches with the examples observed in nature. Our preliminary experimental and numerical results show that at the initial stage of magmatic withdrawal, when the ring-fault is not yet well formed, broad and smooth deflation dominates at the surface. As the withdrawal increases, narrower subsidence bowl develops accompanied by the upward propagation of the ring-faulting. This indicates that the broad deflation, affecting the entire volcano edifice, is primarily driven by the contraction of the

  3. GEM Plate Boundary Simulations for the Plate Boundary Observatory: A Program for Understanding the Physics of Earthquakes on Complex Fault Networks via Observations, Theory and Numerical Simulation

    Science.gov (United States)

    Rundle, J. B.; Rundle, P. B.; Klein, W.; de sa Martins, J.; Tiampo, K. F.; Donnellan, A.; Kellogg, L. H.

    The last five years have seen unprecedented growth in the amount and quality of geodetic data collected to characterize crustal deformation in earthquake-prone areas such as California and Japan. The installation of the Southern California Integrated Geodetic Network (SCIGN) and the Bay Area Regional Deformation (BARD) network are two examples. As part of the recently proposed Earthscope NSF/GEO/EAR/MRE initiative, the Plate Boundary Observatory (PBO) plans to place more than a thousand GPS, strainmeters, and deformation sensors along the active plate boundary of the western coast of the United States, Mexico and Canada (http://www.earthscope.org/pbo.com.html). The scientific goals of PBO include understanding how tectonic plates interact, together with an emphasis on understanding the physics of earthquakes. However, the problem of understanding the physics of earthquakes on complex fault networks through observations alone is complicated by our inability to study the problem in a manner familiar to laboratory scientists, by means of controlled, fully reproducible experiments. We have therefore been motivated to construct a numerical simulation technology that will allow us to study earthquake physics via numerical experiments. To be considered successful, the simulations must not only produce observables that are maximally similar to those seen by the PBO and other observing programs, but in addition the simulations must provide dynamical predictions that can be falsified by means of observations on the real fault networks. In general, the dynamical behavior of earthquakes on complex fault networks is a result of the interplay between the geometric structure of the fault network and the physics of the frictional sliding process. In constructing numerical simulations of a complex fault network, we will need to solve a variety of problems, including the development of analysis techniques (also called data mining), data assimilation, space-time pattern definition

  4. Numerical modeling of fracking fluid and methane migration through fault zones in shale gas reservoirs

    Science.gov (United States)

    Taherdangkoo, Reza; Tatomir, Alexandru; Sauter, Martin

    2017-04-01

    Hydraulic fracturing operation in shale gas reservoir has gained growing interest over the last few years. Groundwater contamination is one of the most important environmental concerns that have emerged surrounding shale gas development (Reagan et al., 2015). The potential impacts of hydraulic fracturing could be studied through the possible pathways for subsurface migration of contaminants towards overlying aquifers (Kissinger et al., 2013; Myers, 2012). The intent of this study is to investigate, by means of numerical simulation, two failure scenarios which are based on the presence of a fault zone that penetrates the full thickness of overburden and connect shale gas reservoir to aquifer. Scenario 1 addresses the potential transport of fracturing fluid from the shale into the subsurface. This scenario was modeled with COMSOL Multiphysics software. Scenario 2 deals with the leakage of methane from the reservoir into the overburden. The numerical modeling of this scenario was implemented in DuMux (free and open-source software), discrete fracture model (DFM) simulator (Tatomir, 2012). The modeling results are used to evaluate the influence of several important parameters (reservoir pressure, aquifer-reservoir separation thickness, fault zone inclination, porosity, permeability, etc.) that could affect the fluid transport through the fault zone. Furthermore, we determined the main transport mechanisms and circumstances in which would allow frack fluid or methane migrate through the fault zone into geological layers. The results show that presence of a conductive fault could reduce the contaminant travel time and a significant contaminant leakage, under certain hydraulic conditions, is most likely to occur. Bibliography Kissinger, A., Helmig, R., Ebigbo, A., Class, H., Lange, T., Sauter, M., Heitfeld, M., Klünker, J., Jahnke, W., 2013. Hydraulic fracturing in unconventional gas reservoirs: risks in the geological system, part 2. Environ Earth Sci 70, 3855

  5. Permeability evolution of normal faults with clay smear: insights from structural observations in water saturated sandbox models and numerical simulations

    Science.gov (United States)

    Kettermann, Michael; Urai, Janos L.; Vrolijk, Peter J.

    2017-04-01

    Fault processes are complex phenomena that defy reliable prediction. Clay smear in particular is difficult to predict for sub-surface flow applications and would benefit from an improved understanding of controlling processes. In this study, we present a series of water-saturated sandbox experiments producing large clay smear surfaces up to 500 cm2. In these experiments, we couple across-fault flow measurements with structural analysis of post-mortem excavated clay smear surfaces. To develop a tool for evaluating the evolving fault structure during formation, we compare measured flow data to simplified numerical flow simulations. Results show diagnostic relationships between the observed fault structures and measured cross-fault flow. In experiments with one or two clay layers and a cumulative thickness of 10 mm and 100 mm displacement, we observe that normally consolidated clay, in a structural domain of graben faulting, initially yields in hybrid brittle/ductile failure. Characteristic for this type of failure is an early breaching of the clay layer by brittle fracturing causing increased cross-fault flow. However, the type of failure varies laterally and shear failure occurs as well. We observed that holes preferably form beneath extensional parts of the footwall cutoff. These can be identified in map-view as the fault curves towards the hanging wall. During the evolution of the fault, this is typically followed by fault back-stepping, formation of clay smears and reworking of clay fragments in the fault. These processes lead to slower increases of cross-fault flux. Holes that formed during the early breaching of the clay layer mostly remain open during the evolution of a fault, although there is some evidence for occasional resealing of holes. Fault zones are segmented by fault lenses, breached relays and clay smears in which sand and clay mix by deformation. Experiments with two clay layers show that holes rarely form at the same position on the fault planes

  6. 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

  7. Numerical reconstruction of Late-Cenosoic evolution of normal-fault scarps in Baikal Rift Zone

    Science.gov (United States)

    Byzov, Leonid; San'kov, Vladimir

    2014-05-01

    Numerical landscape development modeling has recently become a popular tool in geo-logic and geomorphic investigations. We employed this technique to reconstruct Late-Cenosoic evolution of Baikal Rift Zone mountains. The objects of research were Barguzin Range and Svyatoy Nos Upland. These structures are formed under conditions of crustal extension and bounded by active normal faults. In our experiments we used instruments, engineered by Greg Tucker (University of Colo-rado) - CHILD (Channel-Hillslope Integrated Landscape Development) and 'Bedrock Fault Scarp'. First program allowed constructing the complex landscape model considering tectonic uplift, fluvial and hillslope processes; second program is used for more accurate simulating of triangular facet evolution. In general, our experiments consisted in testing of tectonic parameters, and climatic char-acteristic, erosion and diffusion properties, hydraulic geometry were practically constant except for some special runs. Numerous experiments, with various scenarios of development, showed that Barguzin range and Svyatoy Nos Upland has many common features. These structures characterized by internal differentiation, which appear in height and shape of slopes. At the same time, individual segments of these objects are very similar - this conclusion refers to most developing parts, with pronounced facets and V-shaped valleys. Accordingly modelling, these landscapes are in a steady state and are undergoing a uplift with rate 0,4 mm/yr since Early Pliocene (this solution accords with AFT-dating). Lower segments of Barguzin Range and Svyatoy Nos Upland also have some general fea-tures, but the reasons of such similarity probably are different. In particular, southern segment of Svyatoy Nos Upland, which characterized by relative high slope with very weak incision, may be formed as result very rapid fault movement or catastrophic landslide. On the other hand, a lower segment of Barguzin Range (Ulun segment, for example

  8. A numerical model for modeling microstructure and THM couplings in fault gouges

    Science.gov (United States)

    Veveakis, M.; Rattez, H.; Stefanou, I.; Sulem, J.; Poulet, T.

    2017-12-01

    When materials are subjected to large deformations, most of them experience inelastic deformations, accompanied by a localization of these deformations into a narrow zone leading to failure. Localization is seen as an instability from the homogeneous state of deformation. Therefore a first approach to study it consists at looking at the possible critical conditions for which the constitutive equations of the material allow a bifurcation point (Rudnicki & Rice 1975). But in some cases, we would like to know the evolution of the material after the onset of localization. For example, a fault in the crustal part of the lithosphere is a shear band and the study of this localized zone enables to extract information about seismic slip. For that, we need to approximate the solution of a nonlinear boundary value problem numerically. It is a challenging task due to the complications that arise while dealing with a softening behavior. Indeed, the classical continuum theory cannot be used because the governing system of equations is ill-posed (Vardoulakis 1985). This ill-posedness can be tracked back to the fact that constitutive models don't contain material parameters with the dimension of a length. It leads to what is called "mesh dependency" for numerical simulations, as the deformations localize in only one element of the mesh and the behavior of the system depends thus on the mesh size. A way to regularize the problem is to resort to continuum models with microstructure, such as Cosserat continua (Sulem et al. 2011). Cosserat theory is particularly interesting as it can explicitly take into account the size of the microstructure in a fault gouge. Basically, it introduces 3 degrees of freedom of rotation on top of the 3 translations (Godio et al. 2016). The original work of (Mühlhaus & Vardoulakis 1987) is extended in 3D and thermo-hydro mechanical couplings are added to the model to study fault system in the crustal part of the lithosphere. The system of equations is

  9. Reconciling experimental and static-dynamic numerical estimations of seismic anisotropy in Alpine Fault mylonites

    Science.gov (United States)

    Adam, L.; Frehner, M.; Sauer, K. M.; Toy, V.; Guerin-Marthe, S.; Boulton, C. J.

    2017-12-01

    Reconciling experimental and static-dynamic numerical estimations of seismic anisotropy in Alpine Fault mylonitesLudmila Adam1, Marcel Frehner2, Katrina Sauer3, Virginia Toy3, Simon Guerin-Marthe4, Carolyn Boulton5(1) University of Auckland, New Zealand, (2) ETH Zurich, Switzerland, (3) University of Otago, New Zealand (4) Durham University, Earth Sciences, United Kingdom (5) Victoria University of Wellington, New Zealand Quartzo-feldspathic mylonites and schists are the main contributors to seismic wave anisotropy in the vicinity of the Alpine Fault (New Zealand). We must determine how the physical properties of rocks like these influence elastic wave anisotropy if we want to unravel both the reasons for heterogeneous seismic wave propagation, and interpret deformation processes in fault zones. To study such controls on velocity anisotropy we can: 1) experimentally measure elastic wave anisotropy on cores at in-situ conditions or 2) estimate wave velocities by static (effective medium averaging) or dynamic (finite element) modelling based on EBSD data or photomicrographs. Here we compare all three approaches in study of schist and mylonite samples from the Alpine Fault. Volumetric proportions of intrinsically anisotropic micas in cleavage domains and comparatively isotropic quartz+feldspar in microlithons commonly vary significantly within one sample. Our analysis examines the effects of these phases and their arrangement, and further addresses how heterogeneity influences elastic wave anisotropy. We compare P-wave seismic anisotropy estimates based on millimetres-scale ultrasonic waves under in situ conditions, with simulations that account for micrometre-scale variations in elastic properties of constitutent minerals with the MTEX toolbox and finite-element wave propagation on EBSD images. We observe that the sorts of variations in the distribution of micas and quartz+feldspar within any one of our real core samples can change the elastic wave anisotropy by 10

  10. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults

    Science.gov (United States)

    Yan, Chenguang; Hao, Zhiguo; Zhang, Song; Zhang, Baohui; Zheng, Tao

    2015-01-01

    Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3MJ and a 6.3MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers. PMID:26230392

  11. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults.

    Directory of Open Access Journals (Sweden)

    Chenguang Yan

    Full Text Available Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3 MJ and a 6.3 MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers.

  12. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults.

    Science.gov (United States)

    Yan, Chenguang; Hao, Zhiguo; Zhang, Song; Zhang, Baohui; Zheng, Tao

    2015-01-01

    Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3 MJ and a 6.3 MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers.

  13. Experimental and Numerical Simulation Analysis of Typical Carbon Woven Fabric/Epoxy Laminates Subjected to Lightning Strike

    Science.gov (United States)

    Yin, J. J.; Chang, F.; Li, S. L.; Yao, X. L.; Sun, J. R.; Xiao, Y.

    2017-12-01

    To clarify the evolution of damage for typical carbon woven fabric/epoxy laminates exposed to lightning strike, artificial lightning testing on carbon woven fabric/epoxy laminates were conducted, damage was assessed using visual inspection and damage peeling approaches. Relationships between damage size and action integral were also elucidated. Results showed that damage appearance of carbon woven fabric/epoxy laminate presents circular distribution, and center of the circle located at the lightning attachment point approximately, there exist no damage projected area dislocations for different layers, visual damage territory represents maximum damage scope; visible damage can be categorized into five modes: resin ablation, fiber fracture and sublimation, delamination, ablation scallops and block-shaped ply-lift; delamination damage due to resin pyrolysis and internal pressure exist obvious distinguish; project area of total damage is linear with action integral for the same type specimens, that of resin ablation damage is linear with action integral, but no correlation with specimen type, for all specimens, damage depth is linear with logarithm of action integral. The coupled thermal-electrical model constructed is capable to simulate the ablation damage for carbon woven fabric/epoxy laminates exposed to simulated lightning current through experimental verification.

  14. Numerical modeling of fluid flow in a fault zone: a case of study from Majella Mountain (Italy).

    Science.gov (United States)

    Romano, Valentina; Battaglia, Maurizio; Bigi, Sabina; De'Haven Hyman, Jeffrey; Valocchi, Albert J.

    2017-04-01

    The study of fluid flow in fractured rocks plays a key role in reservoir management, including CO2 sequestration and waste isolation. We present a numerical model of fluid flow in a fault zone, based on field data acquired in Majella Mountain, in the Central Apennines (Italy). This fault zone is considered a good analogue for the massive presence of fluid migration in the form of tar. Faults are mechanical features and cause permeability heterogeneities in the upper crust, so they strongly influence fluid flow. The distribution of the main components (core, damage zone) can lead the fault zone to act as a conduit, a barrier, or a combined conduit-barrier system. We integrated existing information and our own structural surveys of the area to better identify the major fault features (e.g., type of fractures, statistical properties, geometrical and petro-physical characteristics). In our model the damage zones of the fault are described as discretely fractured medium, while the core of the fault as a porous one. Our model utilizes the dfnWorks code, a parallelized computational suite, developed at Los Alamos National Laboratory (LANL), that generates three dimensional Discrete Fracture Network (DFN) of the damage zones of the fault and characterizes its hydraulic parameters. The challenge of the study is the coupling between the discrete domain of the damage zones and the continuum one of the core. The field investigations and the basic computational workflow will be described, along with preliminary results of fluid flow simulation at the scale of the fault.

  15. Salt movements and faulting of the overburden - can numerical modeling predict the fault patterns above salt structures?

    DEFF Research Database (Denmark)

    Clausen, O.R.; Egholm, D.L.; Wesenberg, Rasmus

    among other things the productivity due to the segmentation of the reservoir (Stewart 2006). 3D seismic data above salt structures can map such fault patterns in great detail and studies have shown that a variety of fault patterns exists. Yet, most patterns fall between two end members: concentric....... radiating) can thus be linked to two different styles of salt movement: i) the vertical rising of a salt indenter and ii) the inflation of a ‘salt-balloon’ beneath the deformed strata. The results are in accordance with published analogue and theoretical models, as well as natural systems, and the model may...... the hydrocarbon production from reservoirs located above salt structures is optimized....

  16. Neotectonics of a subduction/strike-slip transition: the northeastern Dominican Republic

    Energy Technology Data Exchange (ETDEWEB)

    Winslow, M.A.; McCann, W.R.

    1985-01-01

    The Septentrional fault system in the northeastern Dominican Republic marks the zone where the North American-Carribean plate boundary is evolving from subduction to strike-slip motion, and where terranes appear to be forming and migrating laterally in a subduction complex/forearc region. On the Island of Hispaniola, slip vectors are oblique to the strike of the Puerto Rico trench, and oblique subduction thrusts the upper plate over normal seafloor. The offshore geology and seismicity of the northern Caribbean suggest that uplift, broad crustal warping, thrusting, and strike-slip faulting (ie. collisional tectonics) should be present in the northern part of the Dominican Republic. The high topography (>1000m), high levels of seismicity, and large earthquakes support the hypothesis of contemporary deformation in Hispaniola. In this region, the subduction regime dies out toward the west, and deformation is transferred to onshore, oblique-slip faults. As this change in tectonic style has occurred in Neogene to Recent times, we are investigating the modern evolution of a plate boundary. We have already documented: (1) the presence of a strike-slip faulting in the northeastern Dominican Republic; (2) an anomalous push-up structure; and (3) a region of numerous splay faults. In conclusion, recent seismicity suggest a wide zone of deformation and variations in interplate motions near Hispaniola. This island lies at the western limit of active underthrusting and at the eastern limit of onshore faulting, i.e., at an important transition from a subduction to strike-slip regime.

  17. Influence of fault asymmetric dislocation on the gravity changes

    Directory of Open Access Journals (Sweden)

    Duan Hurong

    2014-08-01

    Full Text Available A fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth’s crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, energy release associated with rapid movement on active faults is the cause of most earthquakes. The relationship between unevenness dislocation and gravity changes was studied on the theoretical thought of differential fault. Simulated observation values were adopted to deduce the gravity changes with the model of asymmetric fault and the model of Okada, respectively. The characteristic of unevennes fault momentum distribution is from two end points to middle by 0 according to a certain continuous functional increase. However, the fault momentum distribution in the fault length range is a constant when the Okada model is adopted. Numerical simulation experiments for the activities of the strike-slip fault, dip-slip fault and extension fault were carried out, respectively, to find that both the gravity contours and the gravity variation values are consistent when either of the two models is adopted. The apparent difference lies in that the values at the end points are 17. 97% for the strike-slip fault, 25. 58% for the dip-slip fault, and 24. 73% for the extension fault.

  18. Potassic late orogenic Stephanian volcanism in the South West french Massif Central (Decazeville, Figeac, Lacapelle-Marival basins): an example for mantle metasomatism along strike-slip faults?

    OpenAIRE

    Lapierre, Henriette; Basile, Christophe; Berly, Thomas; Canard, Emmanuel

    2008-01-01

    International audience; In the Southwestern part of the French Massif central (Decazeville basin, at the Sillon Houiller fault termination; Figeac and Lacapelle-Marival basins along the Argentat fault), Stephanian volcanism exhibits shoshonitic affinities. Their chondrite-normalized Rare Earth Element (REE) patterns are enriched in light REE, but almost flat for heavy REE, with marked negative Eu anomalies. Primitive mantle-normalized element spectra show negative Nb, Ta, P, Sm, Ti, and posit...

  19. A Framework For Evaluating Comprehensive Fault Resilience Mechanisms In Numerical Programs

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Peng, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bronevetsky, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-01-09

    As HPC systems approach Exascale, their circuit feature will shrink, while their overall size will grow, all at a fixed power limit. These trends imply that soft faults in electronic circuits will become an increasingly significant problem for applications that run on these systems, causing them to occasionally crash or worse, silently return incorrect results. This is motivating extensive work on application resilience to such faults, ranging from generic techniques such as replication or checkpoint/restart to algorithm-specific error detection and resilience techniques. Effective use of such techniques requires a detailed understanding of (1) which vulnerable parts of the application are most worth protecting (2) the performance and resilience impact of fault resilience mechanisms on the application. This paper presents FaultTelescope, a tool that combines these two and generates actionable insights by presenting in an intuitive way application vulnerabilities and impact of fault resilience mechanisms on applications.

  20. Structural evolution of Cenozoic basins in northeastern Tunisia, in response to sinistral strike-slip movement on the El Alia-Teboursouk Fault

    Science.gov (United States)

    Bejaoui, Hamida; Aïfa, Tahar; Melki, Fetheddine; Zargouni, Fouad

    2017-10-01

    This paper resolves the structural complexity of Cenozoic sedimentary basins in northeastern Tunisia. These basins trend NE-SW to ∼ E-W, and are bordered by old fracture networks. Detailed descriptions of the structural features in outcrop and in subsurface data suggest that the El Alia-Teboursouk Fault zone in the Bizerte area evolved through a series of tectonic events. Cross sections, lithostratigraphic correlations, and interpretation of seismic profiles through the basins show evidence for: (i) a Triassic until Jurassic-Early Cretaceous rifting phase that induced lateral variations of facies and strata thicknesses; (ii) a set of faults oriented NE-SW, NW-SE, N-S, and E-W that guided sediment accumulation in pull-apart basins, which were subject to compressive and transpressive deformation during Eocene (Lutetian-Priabonian), Miocene (Tortonian), and Pliocene-Quaternary; and (iii) NNW-SSE to NS contractional events that occurred during the Late Pliocene. Part of the latest phase has been the formation of different synsedimentary folded structures with significant subsidence inversion. Such events have been responsible for the reactivation of inherited faults, and the intrusion of Triassic evaporites, ensuring the role of a slip layer. The combined effects of the different paleoconstraints and halokinetic movements are at the origin of the evolution of these pull-apart basins. The subsurface data suggest that an important fault displacement occurred during the Mesozoic-Cenozoic. The patterns of sediment accumulation in the different basins reflect a high activity of deep ancient faults.

  1. Faults architecture and growth in clay-limestone alternation. Examples in the S-E Basin alternations (France) and numerical modeling

    International Nuclear Information System (INIS)

    Roche, Vincent

    2011-01-01

    The following work has been carried out in the framework of the studies conducted by IRSN in support of its safety evaluation of the geological disposal programme of high and intermediate level, long-lived radioactive waste. Such a disposal is planned to be hosted by the Callovian-Oxfordian indurate clay formation between two limestone formations in eastern Paris basin, France. Hypothetical faults may cross-cut this layered section, decreasing the clay containment ability by creating preferential pathways for radioactive solute towards limestones. This study aims at characterising the fault architecture and the normal fault growth in clay/limestone layered sections. Structural analysis and displacement profiles have been carried out in normal faults crossing several decimetres to metre thick sedimentary alternations in the South-Eastern Basin (France) and petrophysical properties have been determined for each layer. The studied faults are simple fault planes or complex fault zones showing are significantly controlled by the layering. The analysis of the fault characteristics and the results obtained on numerical models enlighten several processes such as fault nucleation, fault restriction, and fault growth through layered section. Some studied faults nucleated in the limestone layers, without using pre-existing fractures such as joints, and according to our numerical analysis, a strong stiffness, a low strength contrast between the limestone and the clay layer, and/or s a greater thickness of the clay layer are conditions which favour nucleation of faults in limestone. The range of mechanical properties leading to the fault nucleation in one layer type or another was investigated using a 3D modelling approach. After its nucleation, the fault propagates within a homogeneous medium with a constant displacement gradient until its vertical propagation is stopped by a restrictor. The evidenced restrictors are limestone-clay interfaces or faults in clays, sub

  2. Study on conditional probability of surface rupture: effect of fault dip and width of seismogenic layer

    Science.gov (United States)

    Inoue, N.

    2017-12-01

    The conditional probability of surface ruptures is affected by various factors, such as shallow material properties, process of earthquakes, ground motions and so on. Toda (2013) pointed out difference of the conditional probability of strike and reverse fault by considering the fault dip and width of seismogenic layer. This study evaluated conditional probability of surface rupture based on following procedures. Fault geometry was determined from the randomly generated magnitude based on The Headquarters for Earthquake Research Promotion (2017) method. If the defined fault plane was not saturated in the assumed width of the seismogenic layer, the fault plane depth was randomly provided within the seismogenic layer. The logistic analysis was performed to two data sets: surface displacement calculated by dislocation methods (Wang et al., 2003) from the defined source fault, the depth of top of the defined source fault. The estimated conditional probability from surface displacement indicated higher probability of reverse faults than that of strike faults, and this result coincides to previous similar studies (i.e. Kagawa et al., 2004; Kataoka and Kusakabe, 2005). On the contrary, the probability estimated from the depth of the source fault indicated higher probability of thrust faults than that of strike and reverse faults, and this trend is similar to the conditional probability of PFDHA results (Youngs et al., 2003; Moss and Ross, 2011). The probability of combined simulated results of thrust and reverse also shows low probability. The worldwide compiled reverse fault data include low fault dip angle earthquake. On the other hand, in the case of Japanese reverse fault, there is possibility that the conditional probability of reverse faults with less low dip angle earthquake shows low probability and indicates similar probability of strike fault (i.e. Takao et al., 2013). In the future, numerical simulation by considering failure condition of surface by the source

  3. Faulting and off-axis submarine massive sulfide accumulation at slow spreading mid-ocean ridges: A numerical modeling perspective

    Science.gov (United States)

    Andersen, C.; Theissen-Krah, S.; Hannington, M.; Rüpke, L.; Petersen, S.

    2017-06-01

    The potential of mining seafloor massive sulfide deposits for metals such as Cu, Zn, and Au is currently debated. One key challenge is to predict where the largest deposits worth mining might form, which in turn requires understanding the pattern of subseafloor hydrothermal mass and energy transport. Numerical models of heat and fluid flow are applied to illustrate the important role of fault zone properties (permeability and width) in controlling mass accumulation at hydrothermal vents at slow spreading ridges. We combine modeled mass-flow rates, vent temperatures, and vent field dimensions with the known fluid chemistry at the fault-controlled Logatchev 1 hydrothermal field of the Mid-Atlantic Ridge. We predict that the 135 kilotons of SMS at this site (estimated by other studies) can have accumulated with a minimum depositional efficiency of 5% in the known duration of hydrothermal venting (58,200 year age of the deposit). In general, the most productive faults must provide an efficient fluid pathway while at the same time limit cooling due to mixing with entrained cold seawater. This balance is best met by faults that are just wide and permeable enough to control a hydrothermal plume rising through the oceanic crust. Model runs with increased basal heat input, mimicking a heat flow contribution from along-axis, lead to higher mass fluxes and vent temperatures, capable of significantly higher SMS accumulation rates. Nonsteady state conditions, such as the influence of a cooling magmatic intrusion beneath the fault zone, also can temporarily increase the mass flux while sustaining high vent temperatures.

  4. Active and recent strike-slip tectonics

    Science.gov (United States)

    Nur, Amos; Boccaletti, Mario

    An international workshop cosponsored by the Department of Geology, University of Florence, Italy and the Department of Geophysics, Stanford University, Stanford, Calif., was held in Florence, Italy, April 18-20, 1989,on the topic of active and recent strike-slip tectonics in the continental crust. Workshop participants from Turkey, Ethiopia, Israel, Greece, and various universities in Italy, Spain, West Germany, France, the United Kingdom, Brazil, and the United States reported on a broad range of studies involving strike-slip faulting in continental crustal setting. As it turned out, much of the work reported on involved aspects of strike-slip faulting that are only poorly understood, especially crustal deformation, which is distributed over a multiplicity of faults, or even fault domains.One of the rewarding aspects of this workshop was the diversity of geographic areas and geological settings covered by the reporters. The north and east Anatolian faults, the Dead Sea transform zone, western Turkey, north and central Greece, Malta, Sicily, southern Italy, the bethic Cordillera in southern Spain, Tunisia, Tibet and southwest China, offshore Brazil, Alaska, Nevada, and California. A recurring observation reported for all those areas was mixed mode faulting, i.e., the coterminous or sequential occurrence of strike-slip and normal faulting, or strike-slip and thrust, and in many instances also strikeslip, normal and thrust faulting in a single tectonic setting.

  5. How Faults Shape the Earth.

    Science.gov (United States)

    Bykerk-Kauffman, Ann

    1992-01-01

    Presents fault activity with an emphasis on earthquakes and changes in continent shapes. Identifies three types of fault movement: normal, reverse, and strike faults. Discusses the seismic gap theory, plate tectonics, and the principle of superposition. Vignettes portray fault movement, and the locations of the San Andreas fault and epicenters of…

  6. Numerical modeling of fracking fluid migration through fault zones and fractures in the North German Basin

    Science.gov (United States)

    Pfunt, Helena; Houben, Georg; Himmelsbach, Thomas

    2016-09-01

    Gas production from shale formations by hydraulic fracturing has raised concerns about the effects on the quality of fresh groundwater. The migration of injected fracking fluids towards the surface was investigated in the North German Basin, based on the known standard lithology. This included cases with natural preferential pathways such as permeable fault zones and fracture networks. Conservative assumptions were applied in the simulation of flow and mass transport triggered by a high pressure boundary of up to 50 MPa excess pressure. The results show no significant fluid migration for a case with undisturbed cap rocks and a maximum of 41 m vertical transport within a permeable fault zone during the pressurization. Open fractures, if present, strongly control the flow field and migration; here vertical transport of fracking fluids reaches up to 200 m during hydraulic fracturing simulation. Long-term transport of the injected water was simulated for 300 years. The fracking fluid rises vertically within the fault zone up to 485 m due to buoyancy. Progressively, it is transported horizontally into sandstone layers, following the natural groundwater flow direction. In the long-term, the injected fluids are diluted to minor concentrations. Despite the presence of permeable pathways, the injected fracking fluids in the reported model did not reach near-surface aquifers, either during the hydraulic fracturing or in the long term. Therefore, the probability of impacts on shallow groundwater by the rise of fracking fluids from a deep shale-gas formation through the geological underground to the surface is small.

  7. Dynamical instability produces transform faults at mid-ocean ridges.

    Science.gov (United States)

    Gerya, Taras

    2010-08-27

    Transform faults at mid-ocean ridges--one of the most striking, yet enigmatic features of terrestrial plate tectonics--are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps.

  8. Basement Fault Reactivation by Fluid Injection into Sedimentary Reservoirs

    Science.gov (United States)

    Peter, Eichhubl; Fan, Zhiqiang; Zhu, Cheng

    2017-04-01

    Many suspected injection-induced earthquakes occur in crystalline basement rather than in the overlying sedimentary injection reservoir. To address why earthquakes nucleate in the basement rather than the injection layer we investigate the relationship between pore pressure diffusion, rock matrix deformation, and induced fault reactivation through 3D fully coupled poroelastic finite element models. These models simulate the temporal and spatial perturbation of pore pressure and solid stresses within a basement fault that extends into overlying sedimentary layers and that is conductive for flow along the fault but a barrier for flow across. We compare the effects of direct pore pressure communication and indirect poroelastic stress transfer from the injection reservoir to the fault on increasing the Coulomb failure stress that could reactivate the basement fault for normal, reverse, and strike-slip faulting stress regimes. Our numerical results demonstrate that volumetric expansion of the reservoir causes a bending of the fault near the injector and induces shear tractions along the downdip direction of the fault in the basement. These induced shear tractions act to increase the Coulomb failure stress for a normal faulting stress regime, and decrease the Coulomb failure stress for a reverse faulting regime. For a strike-slip faulting stress regime, the induced shear tractions increase the Coulomb failure stress both in the reservoir and basement. The induced normal traction on the fault reduces the Coulomb failure stress in all three tectonic regimes, but is larger in the reservoir than in the basement due to the more pronounced poroelastic effect in the reservoir. As a result, strike-slip stress regimes favor fault reactivation in the basement. Whereas the magnitude of the direct pore pressure increase exceeds the magnitude of induced poroelastic stress change, the poroelastic stress change increases the Coulomb failure stress in the basement fault for the normal

  9. Active faults and related Late Quaternary deformation along the Northwestern Himalayan Frontal Zone, India

    Directory of Open Access Journals (Sweden)

    T. Nakata

    2003-06-01

    Full Text Available Numerous newly-identified traces of active faults in the Himalayan foothill zone along the HFF around Chandigarh, in Pinjore Dun, along the piedmont zone of the Lower Siwalik hill front and within the Lower Tertiary hill range reveal the pattern of thrust and strike-slip faulting, striking parallel to the principal structural trend (NNW-SSE of the orogenic belt. The active Chandigarh Fault, Pinjore Garden Fault and Barsar thrust have vertically dislocated, warped and backtilted fluvial and alluvial-fan surfaces made up of Late Pleistocene-Holocene sediments. West- and southwest-facing fault scarplets with heights ranging from 12 to 50 m along these faults suggest continued tectonic movement through Late Pleistocene to recent times. Gentle warping and backtilting of the terraces on the hanging wall sides of the faults indicate fault-bend folding. These active faults are the manifestation of north-dipping imbricated thrust faults branching out from the major fault systems like the Main Boundary Fault (MBF and Himalayan Frontal Fault (HFF, probably merging down northward into a décollement. The Taksal Fault, striking NNW-SSE, shows prominent right-lateral movement marked by lateral offset of streams and younger Quaternary terraces and occupies a narrow deep linear valley along the fault trace. Right stepping along this fault has resulted in formation of a small pull-apart basin. Fault scarplets facing ENE and WSW are the manifestation of dip-slip movement. This fault is an example of slip-partitioning between the strike-slip and thrust faults, suggesting ongoing oblique convergence of the Indian plate and northward migration of a tectonic sliver. Slip rate along the Taksal Fault has been calculated as 2.8 mm/yr. Preliminary trench investigation at the base of the Chandigarh Fault Scarp has revealed total displacement of 3.5 m along a low angle thrust fault with variable dip of 20° to 46° due northeast, possibly the result of one

  10. Large-scale thermal convection of viscous fluids in a faulted system: 3D test case for numerical codes

    Science.gov (United States)

    Magri, Fabien; Cacace, Mauro; Fischer, Thomas; Kolditz, Olaf; Wang, Wenqing; Watanabe, Norihiro

    2017-04-01

    In contrast to simple homogeneous 1D and 2D systems, no appropriate analytical solutions exist to test onset of thermal convection against numerical models of complex 3D systems that account for variable fluid density and viscosity as well as permeability heterogeneity (e.g. presence of faults). Owing to the importance of thermal convection for the transport of energy and minerals, the development of a benchmark test for density/viscosity driven flow is crucial to ensure that the applied numerical models accurately simulate the physical processes at hands. The presented study proposes a 3D test case for the simulation of thermal convection in a faulted system that accounts for temperature dependent fluid density and viscosity. The linear stability analysis recently developed by Malkovsky and Magri (2016) is used to estimate the critical Rayleigh number above which thermal convection of viscous fluids is triggered. The numerical simulations are carried out using the finite element technique. OpenGeoSys (Kolditz et al., 2012) and Moose (Gaston et al., 2009) results are compared to those obtained using the commercial software FEFLOW (Diersch, 2014) to test the ability of widely applied codes in matching both the critical Rayleigh number and the dynamical features of convective processes. The methodology and Rayleigh expressions given in this study can be applied to any numerical model that deals with 3D geothermal processes in faulted basins as by example the Tiberas Basin (Magri et al., 2016). References Kolditz, O., Bauer, S., Bilke, L., Böttcher, N., Delfs, J. O., Fischer, T., U. J. Görke, T. Kalbacher, G. Kosakowski, McDermott, C. I., Park, C. H., Radu, F., Rink, K., Shao, H., Shao, H.B., Sun, F., Sun, Y., Sun, A., Singh, K., Taron, J., Walther, M., Wang,W., Watanabe, N., Wu, Y., Xie, M., Xu, W., Zehner, B., 2012. OpenGeoSys: an open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media. Environmental

  11. New evidence on the state of stress of the san andreas fault system.

    Science.gov (United States)

    Zoback, M D; Zoback, M L; Mount, V S; Suppe, J; Eaton, J P; Healy, J H; Oppenheimer, D; Reasenberg, P; Jones, L; Raleigh, C B; Wong, I G; Scotti, O; Wentworth, C

    1987-11-20

    Contemporary in situ tectonic stress indicators along the San Andreas fault system in central California show northeast-directed horizontal compression that is nearly perpendicular to the strike of the fault. Such compression explains recent uplift of the Coast Ranges and the numerous active reverse faults and folds that trend nearly parallel to the San Andreas and that are otherwise unexplainable in terms of strike-slip deformation. Fault-normal crustal compression in central California is proposed to result from the extremely low shear strength of the San Andreas and the slightly convergent relative motion between the Pacific and North American plates. Preliminary in situ stress data from the Cajon Pass scientific drill hole (located 3.6 kilometers northeast of the San Andreas in southern California near San Bernardino, California) are also consistent with a weak fault, as they show no right-lateral shear stress at approximately 2-kilometer depth on planes parallel to the San Andreas fault.

  12. 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

  13. The northwest trending north Boquerón Bay-Punta Montalva Fault Zone; A through going active fault system in southwestern Puerto Rico

    Science.gov (United States)

    Roig‐Silva, Coral Marie; Asencio, Eugenio; Joyce, James

    2013-01-01

    The North Boquerón Bay–Punta Montalva fault zone has been mapped crossing the Lajas Valley in southwest Puerto Rico. Identification of the fault was based upon detailed analysis of geophysical data, satellite images, and field mapping. The fault zone consists of a series of Cretaceous bedrock faults that reactivated and deformed Miocene limestone and Quaternary alluvial fan sediments. The fault zone is seismically active (local magnitude greater than 5.0) with numerous locally felt earthquakes. Focal mechanism solutions suggest strain partitioning with predominantly east–west left-lateral displacements with small normal faults striking mostly toward the northeast. Northeast-trending fractures and normal faults can be found in intermittent streams that cut through the Quaternary alluvial fan deposits along the southern margin of the Lajas Valley, an east–west-trending 30-km-long fault-controlled depression. Areas of preferred erosion within the alluvial fan trend toward the west-northwest parallel to the onland projection of the North Boquerón Bay fault. The North Boquerón Bay fault aligns with the Punta Montalva fault southeast of the Lajas Valley. Both faults show strong southward tilting of Miocene strata. On the western end, the Northern Boquerón Bay fault is covered with flat-lying Holocene sediments, whereas at the southern end the Punta Montalva fault shows left-lateral displacement of stream drainage on the order of a few hundred meters.

  14. The Geomorphological Developments Along the East Anatolian Fault Zone, Turkey

    Science.gov (United States)

    Saber, R.; Caglayan, A.; Isik, V.; Seyitoglu, G.

    2014-12-01

    The collision of Eurasia with Arabia has given rise to intracontinental shortening in SE Turkey and development of large scale fault zones. The East Anatolian Fault Zone (EAFZ), a major active fault zone over 700 km in length with NE-striking, defines the boundary zone between Eurasia plate and Anatolian micro-plate. Although the northeastern continuation of the zone merges into the North Anatolian Fault Zone at Karliova region, the southwestern continuation has been the subject of some debate. The zone is characterized by numerous, complex faults and segmented surface ruptures. It cuts and offsets several distinctive units in east and southeast Turkey. The portion of the EAFZ examined in this study extends from Celikhan to Turkoglu. Active fault strands in this portion of the EAFZ is termed the Erkenek and Golbasi segments. The zone is made of several NE-SW closely spaced strands cut across Mesozoic-to-Tertiary variable rock units and structures, indicating inception of strike-slip motion in Quaternary and characterized by a series of basins. Fault-related several morphological features have been mapped are within the study area, suggesting the left-lateral motion of fault strands along this part of the EAFZ. Offset streams, beheaded channels, pressure and shutter ridges, linear valleys and ridges and sag ponds are prominent morpho-tectonic features. Offset streams have been measured as few meters to hundreds of meters and show sinistral displacement along the fault zone. Fault scarps, several tens of metres high, are developed in fan deposits along the length of the fault strands. Forming the set of linear sag ponds in Golbasi reveals extentional activity of the EAFZ in this area. Motion of fault strands formed linear valleys and ridges parallel to the faults which is most remarkable features. Our geomorphic studies demonstrated the ongoing activity of the the EAFZ between Celikhan to Turkoglu regions.

  15. Release fault: A variety of cross fault in linked extensional fault systems, in the Sergipe-Alagoas Basin, NE Brazil

    Science.gov (United States)

    Destro, Nivaldo

    1995-05-01

    Two types of cross faults are herein recognized: transfer faults and the newly termed release faults. Transfer faults form where cross faults connect distinct normal faults and horizontal displacements predominate over vertical ones. In contrast, release faults form where cross faults associated with individual normal faults die out within the hangingwall before connecting to other normal faults, and have predominantly vertical displacements. Release faults are geometrically required to accommodate variable displacements along the strike of a normal fault. Thus, they form to release the bending stresses in the hangingwall, and do not cut normal fault planes nor detachment surfaces at depth. Release faults have maximum throws adjacent to normal faults, and may be nearly perpendicular or obliquely oriented to the strike of the latter. Such geometry appears not to depend upon pre-existing weaknesses, but such variable orientation to normal faults is an inherent property of release faults. Release faults commonly appear as simple normal faults in seismic sections, without implying extension along the strike of rift and basins. Three-dimensional strain deformation occurs in the hangingwall only between the terminations of an individual normal fault, but regionally, release faulting is associated with plane strain deformation in linked extensional fault systems.

  16. Constraining recent fault offsets with statistical and geometrical methods: Example from the Jasneuf Fault (Western Alps, France)

    Science.gov (United States)

    Billant, Jérémy; Bellier, Olivier; Godard, Vincent; Hippolyte, Jean-Claude

    2016-12-01

    We propose two new approaches regarding recent fault offset measurements by studying the seismogenic potential of the Jasneuf Fault. The NE trending right-lateral strike-slip Jasneuf Fault is the southwestern extension of the Belledonne fault system in the Vercors Massif. This fault, which is located in an intraplate domain, does not show strongly associated seismicity but displays morphological anomalies that are related to recent faulting (right-lateral offset of Late Cenozoic cliffs, recent talwegs, and post Günz scarps). The two methods that we use to quantify fault slip are as follows. 1 - Recursive measurements of stream offsets are conducted. This analysis reveals that a stream network can display characteristic distances between streams that can be mistakenly interpreted as long-term cumulative fault offsets. A comparison of the apparent stream offset values and stream spacing values is necessary to identify the true offsets. 2 - We propose a new method that enables us to determine the fault offset and kinematics by using recursive measurements of topographic apparent offsets to counter the lack of morphologic features that are used to determine piercing points or lines. This method enables us to define each possible slip vector for numerous artificial piercing points along a fault. The slip vector that is shared by these piercing points is the true slip vector. By applying these methodologies, we determine that the Jasneuf Fault has accumulated slip since the Messinian, which corresponds to an average slip rate of 0.13 ± 0.03 mm year-1. The extension of the fault is poorly constrained. Nevertheless, if we do not consider the potential aseismic (creep slip) component of the faulting, we calculate that this fault could generate Mw 5.7 earthquakes every 500 years according to Wells and Coppersmith's scaling laws and by assuming that the faulting is limited to the sedimentary cover and the Vercors Plateau.

  17. Use of integrated analogue and numerical modelling to predict tridimensional fracture intensity in fault-related-folds.

    Science.gov (United States)

    Pizzati, Mattia; Cavozzi, Cristian; Magistroni, Corrado; Storti, Fabrizio

    2016-04-01

    Fracture density pattern predictions with low uncertainty is a fundamental issue for constraining fluid flow pathways in thrust-related anticlines in the frontal parts of thrust-and-fold belts and accretionary prisms, which can also provide plays for hydrocarbon exploration and development. Among the drivers that concur to determine the distribution of fractures in fold-and-thrust-belts, the complex kinematic pathways of folded structures play a key role. In areas with scarce and not reliable underground information, analogue modelling can provide effective support for developing and validating reliable hypotheses on structural architectures and their evolution. In this contribution, we propose a working method that combines analogue and numerical modelling. We deformed a sand-silicone multilayer to eventually produce a non-cylindrical thrust-related anticline at the wedge toe, which was our test geological structure at the reservoir scale. We cut 60 serial cross-sections through the central part of the deformed model to analyze faults and folds geometry using dedicated software (3D Move). The cross-sections were also used to reconstruct the 3D geometry of reference surfaces that compose the mechanical stratigraphy thanks to the use of the software GoCad. From the 3D model of the experimental anticline, by using 3D Move it was possible to calculate the cumulative stress and strain underwent by the deformed reference layers at the end of the deformation and also in incremental steps of fold growth. Based on these model outputs it was also possible to predict the orientation of three main fractures sets (joints and conjugate shear fractures) and their occurrence and density on model surfaces. The next step was the upscaling of the fracture network to the entire digital model volume, to create DFNs.

  18. Correlation of data on strain accumulation adjacent to the San Andreas Fault with available models

    Science.gov (United States)

    Turcotte, Donald L.

    1986-01-01

    Theoretical and numerical studies of deformation on strike slip faults were performed and the results applied to geodetic observations performed in the vicinity of the San Andreas Fault in California. The initial efforts were devoted to an extensive series of finite element calculations of the deformation associated with cyclic displacements on a strike-slip fault. Measurements of strain accumulation adjacent to the San Andreas Fault indicate that the zone of strain accumulation extends only a few tens of kilometers away from the fault. There is a concern about the tendency to make geodetic observations along the line to the source. This technique has serious problems for strike slip faults since the vector velocity is also along the fault. Use of a series of stations lying perpendicular to the fault whose positions are measured relative to a reference station are suggested to correct the problem. The complexity of faulting adjacent to the San Andreas Fault indicated that the homogeneous elastic and viscoelastic approach to deformation had serious limitations. These limitation led to the proposal of an approach that assumes a fault is composed of a distribution of asperities and barriers on all scales. Thus, an earthquake on a fault is treated as a failure of a fractal tree. Work continued on the development of a fractal based model for deformation in the western United States. In order to better understand the distribution of seismicity on the San Andreas Fault system a fractal analog was developed. The fractal concept also provides a means of testing whether clustering in time or space is a scale-invariant process.

  19. A bottom-driven mechanism for distributed faulting in the Gulf of California rift

    Science.gov (United States)

    Persaud, Patricia; Tan, Eh; Contreras, Juan; Lavier, Luc

    2017-11-01

    Observations of active faulting in the continent-ocean transition of the Northern Gulf of California show multiple oblique-slip faults distributed in a 200 × 70 km2 area developed some time after a westward relocation of the plate boundary at 2 Ma. In contrast, north and south of this broad pull-apart structure, major transform faults accommodate Pacific-North America plate motion. Here we propose that the mechanism for distributed brittle deformation results from the boundary conditions present in the Northern Gulf, where basal shear is distributed between the Cerro Prieto strike-slip fault (southernmost fault of the San Andreas fault system) and the Ballenas Transform Fault. We hypothesize that in oblique-extensional settings whether deformation is partitioned in a few dip-slip and strike-slip faults, or in numerous oblique-slip faults may depend on (1) bottom-driven, distributed extension and shear deformation of the lower crust or upper mantle, and (2) the rift obliquity. To test this idea, we explore the effects of bottom-driven shear on the deformation of a brittle elastic-plastic layer with the help of pseudo-three dimensional numerical models that include side forces. Strain localization results when the basal shear abruptly increases in a step-function manner while oblique-slip on numerous faults dominates when basal shear is distributed. We further explore how the style of faulting varies with obliquity and demonstrate that the style of delocalized faulting observed in the Northern Gulf of California is reproduced in models with an obliquity of 0.7 and distributed basal shear boundary conditions, consistent with the interpreted obliquity and boundary conditions of the study area.

  20. Source model of the 1703 Genroku Kanto earthquake tsunami based on historical documents and numerical simulations: modeling of an offshore fault along the Sagami Trough

    Science.gov (United States)

    Yanagisawa, Hideaki; Goto, Kazuhisa

    2017-10-01

    The 1703 Genroku Kanto earthquake and the resulting tsunami caused catastrophic damage in the Kanto region of Japan. Previous modeling of the 1703 earthquake applied inversion analyses of the observed terrestrial crustal deformations along the coast of the southern Boso Peninsula and revealed that the tsunami was generated along the Sagami Trough. Although these models readily explained the observed crustal deformation, they were unable to model an offshore fault along the Sagami Trough because of difficulties related to the distance of the offshore fault from the shoreline. In addition, information regarding the terrestrial crustal deformation is insufficient to constrain such inverted models. To model an offshore fault and investigate the triggering of large tsunamis off the Pacific coast of the Boso Peninsula, we studied historical documents related to the 1703 tsunami from Choshi City. Based on these historical documents, we estimated tsunami heights of ≥5.9, 11.4-11.7, ≥7.7, 10.8 and ≥4.8 m for the Choshi City regions of Isejiga- ura, Kobatake- ike, Nagasaki, Tokawa and Na'arai, respectively. Although previous studies assumed that the tsunami heights ranged from 3.0 to 4.0 m in Choshi City, we revealed that the tsunami reached heights exceeded 11 m in the city. We further studied the fault model of the 1703 Genroku Kanto earthquake numerically using the newly obtained tsunami height data. Consequently, we determined that the source of the 1703 earthquake was a 120-km-long offshore fault along the Sagami Trough, which is in close proximity to the Japan Trench. Our results suggest that earthquake energies resulting in magnitudes greater than Mw 8.32 along the entire length of the Sagami Trough could have been released during the 1703 Genroku Kanto earthquake.[Figure not available: see fulltext.

  1. 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.

  2. Deeper penetration of large earthquakes on seismically quiescent faults.

    Science.gov (United States)

    Jiang, Junle; Lapusta, Nadia

    2016-06-10

    Why many major strike-slip faults known to have had large earthquakes are silent in the interseismic period is a long-standing enigma. One would expect small earthquakes to occur at least at the bottom of the seismogenic zone, where deeper aseismic deformation concentrates loading. We suggest that the absence of such concentrated microseismicity indicates deep rupture past the seismogenic zone in previous large earthquakes. We support this conclusion with numerical simulations of fault behavior and observations of recent major events. Our modeling implies that the 1857 Fort Tejon earthquake on the San Andreas Fault in Southern California penetrated below the seismogenic zone by at least 3 to 5 kilometers. Our findings suggest that such deeper ruptures may occur on other major fault segments, potentially increasing the associated seismic hazard. Copyright © 2016, American Association for the Advancement of Science.

  3. Numerical Control Machine Tool Fault Diagnosis Using Hybrid Stationary Subspace Analysis and Least Squares Support Vector Machine with a Single Sensor

    Directory of Open Access Journals (Sweden)

    Chen Gao

    2017-03-01

    Full Text Available Tool fault diagnosis in numerical control (NC machines plays a significant role in ensuring manufacturing quality. However, current methods of tool fault diagnosis lack accuracy. Therefore, in the present paper, a fault diagnosis method was proposed based on stationary subspace analysis (SSA and least squares support vector machine (LS-SVM using only a single sensor. First, SSA was used to extract stationary and non-stationary sources from multi-dimensional signals without the need for independency and without prior information of the source signals, after the dimensionality of the vibration signal observed by a single sensor was expanded by phase space reconstruction technique. Subsequently, 10 dimensionless parameters in the time-frequency domain for non-stationary sources were calculated to generate samples to train the LS-SVM. Finally, the measured vibration signals from tools of an unknown state and their non-stationary sources were separated by SSA to serve as test samples for the trained SVM. The experimental validation demonstrated that the proposed method has better diagnosis accuracy than three previous methods based on LS-SVM alone, Principal component analysis and LS-SVM or on SSA and Linear discriminant analysis.

  4. 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.

  5. Should doctors strike?

    Science.gov (United States)

    Park, John J; Murray, Scott A

    2014-05-01

    Last year in June, British doctors went on strike for the first time since 1975. Amidst a global economic downturn and with many health systems struggling with reduced finances, around the world the issue of public health workers going on strike is a very real one. Almost all doctors will agree that we should always follow the law, but often the law is unclear or does not cover a particular case. Here we must appeal to ethical discussion. The General Medical Council, in its key guidance document for practising doctors, Good Medical Practice, claims that 'Good doctors make the care of their patients their first concern'. Is this true? And if so, how is this relevant to the issue of striking? One year on since the events, we carefully reflect and argue whether it was right for doctors to pursue strike action, and call for greater discussion of ethical issues such as the recent strikes, particularly among younger members of the profession.

  6. Earthquake fault superhighways

    Science.gov (United States)

    Robinson, D. P.; Das, S.; Searle, M. P.

    2010-10-01

    Motivated by the observation that the rare earthquakes which propagated for significant distances at supershear speeds occurred on very long straight segments of faults, we examine every known major active strike-slip fault system on land worldwide and identify those with long (> 100 km) straight portions capable not only of sustained supershear rupture speeds but having the potential to reach compressional wave speeds over significant distances, and call them "fault superhighways". The criteria used for identifying these are discussed. These superhighways include portions of the 1000 km long Red River fault in China and Vietnam passing through Hanoi, the 1050 km long San Andreas fault in California passing close to Los Angeles, Santa Barbara and San Francisco, the 1100 km long Chaman fault system in Pakistan north of Karachi, the 700 km long Sagaing fault connecting the first and second cities of Burma, Rangoon and Mandalay, the 1600 km Great Sumatra fault, and the 1000 km Dead Sea fault. Of the 11 faults so classified, nine are in Asia and two in North America, with seven located near areas of very dense populations. Based on the current population distribution within 50 km of each fault superhighway, we find that more than 60 million people today have increased seismic hazards due to them.

  7. Development of Hydrologic Characterization Technology of Fault Zones

    Energy Technology Data Exchange (ETDEWEB)

    Karasaki, Kenzi; Onishi, Tiemi; Wu, Yu-Shu

    2008-03-31

    Through an extensive literature survey we find that there is very limited amount of work on fault zone hydrology, particularly in the field using borehole testing. The common elements of a fault include a core, and damage zones. The core usually acts as a barrier to the flow across it, whereas the damage zone controls the flow either parallel to the strike or dip of a fault. In most of cases the damage zone isthe one that is controlling the flow in the fault zone and the surroundings. The permeability of damage zone is in the range of two to three orders of magnitude higher than the protolith. The fault core can have permeability up to seven orders of magnitude lower than the damage zone. The fault types (normal, reverse, and strike-slip) by themselves do not appear to be a clear classifier of the hydrology of fault zones. However, there still remains a possibility that other additional geologic attributes and scaling relationships can be used to predict or bracket the range of hydrologic behavior of fault zones. AMT (Audio frequency Magneto Telluric) and seismic reflection techniques are often used to locate faults. Geochemical signatures and temperature distributions are often used to identify flow domains and/or directions. ALSM (Airborne Laser Swath Mapping) or LIDAR (Light Detection and Ranging) method may prove to be a powerful tool for identifying lineaments in place of the traditional photogrammetry. Nonetheless not much work has been done to characterize the hydrologic properties of faults by directly testing them using pump tests. There are some uncertainties involved in analyzing pressure transients of pump tests: both low permeability and high permeability faults exhibit similar pressure responses. A physically based conceptual and numerical model is presented for simulating fluid and heat flow and solute transport through fractured fault zones using a multiple-continuum medium approach. Data from the Horonobe URL site are analyzed to demonstrate the

  8. Development of Hydrologic Characterization Technology of Fault Zones

    International Nuclear Information System (INIS)

    Karasaki, Kenzi; Onishi, Tiemi; Wu, Yu-Shu

    2008-01-01

    Through an extensive literature survey we find that there is very limited amount of work on fault zone hydrology, particularly in the field using borehole testing. The common elements of a fault include a core, and damage zones. The core usually acts as a barrier to the flow across it, whereas the damage zone controls the flow either parallel to the strike or dip of a fault. In most of cases the damage zone is the one that is controlling the flow in the fault zone and the surroundings. The permeability of damage zone is in the range of two to three orders of magnitude higher than the protolith. The fault core can have permeability up to seven orders of magnitude lower than the damage zone. The fault types (normal, reverse, and strike-slip) by themselves do not appear to be a clear classifier of the hydrology of fault zones. However, there still remains a possibility that other additional geologic attributes and scaling relationships can be used to predict or bracket the range of hydrologic behavior of fault zones. AMT (Audio frequency Magneto Telluric) and seismic reflection techniques are often used to locate faults. Geochemical signatures and temperature distributions are often used to identify flow domains and/or directions. ALSM (Airborne Laser Swath Mapping) or LIDAR (Light Detection and Ranging) method may prove to be a powerful tool for identifying lineaments in place of the traditional photogrammetry. Nonetheless not much work has been done to characterize the hydrologic properties of faults by directly testing them using pump tests. There are some uncertainties involved in analyzing pressure transients of pump tests: both low permeability and high permeability faults exhibit similar pressure responses. A physically based conceptual and numerical model is presented for simulating fluid and heat flow and solute transport through fractured fault zones using a multiple-continuum medium approach. Data from the Horonobe URL site are analyzed to demonstrate the

  9. Models of recurrent strike-slip earthquake cycles and the state of crustal stress

    Science.gov (United States)

    Lyzenga, Gregory A.; Raefsky, Arthur; Mulligan, Stephanie G.

    1991-01-01

    Numerical models of the strike-slip earthquake cycle, assuming a viscoelastic asthenosphere coupling model, are examined. The time-dependent simulations incorporate a stress-driven fault, which leads to tectonic stress fields and earthquake recurrence histories that are mutually consistent. Single-fault simulations with constant far-field plate motion lead to a nearly periodic earthquake cycle and a distinctive spatial distribution of crustal shear stress. The predicted stress distribution includes a local minimum in stress at depths less than typical seismogenic depths. The width of this stress 'trough' depends on the magnitude of crustal stress relative to asthenospheric drag stresses. The models further predict a local near-fault stress maximum at greater depths, sustained by the cyclic transfer of strain from the elastic crust to the ductile asthenosphere. Models incorporating both low-stress and high-stress fault strength assumptions are examined, under Newtonian and non-Newtonian rheology assumptions. Model results suggest a preference for low-stress (a shear stress level of about 10 MPa) fault models, in agreement with previous estimates based on heat flow measurements and other stress indicators.

  10. Spatio-temporal evolution of fault networks: implications for deep radioactive waste disposal sites

    International Nuclear Information System (INIS)

    Hardacre, K.; Scotti, O.

    2001-01-01

    The objective of this work is to provide estimates of both vertical and lateral propagation rates, on time scales of 100 000 years, for the faults systems known to be present today in the region of Bure, the site of an underground rock laboratory. The project is divided into three parts: 1) literature review (fault growth processes and data), 2) benchmarking against data a numerical code that allows for spontaneous development and growth of faults and 3) application to the Bure site. A brief overview of fault growth processes and observed fault propagation rates shows that non-negligible values (20-50 mm/yrs or roughly 5 km in 100 000 years) can be reached. Preliminary results obtained from two numerical simulations 1) fault growth of a pre-existing weaknesses and 2) fault growth of a spontaneously generated fault system, provide encouraging results with values that are comparable with those observed in nature for the growth of normal fault systems. The application to strike-slip system that characterizes the Bure site is still underway. (authors)

  11. Causative Fault of 2016 ML 5.8 Gyeongju Earthquake (SE Korea): Structural and Seismic characteristics

    Science.gov (United States)

    Ha, S.; Cheon, Y.; Lee, Y.; Kim, J.; Kim, K. H.; Son, M.

    2017-12-01

    A ML 5.8 earthquake, the largest instrumental earthquake in the Korean peninsula, occurred on 12 September 2016 in the Gyeongju-city, SE Korea, where is regarded as a stable intraplate region. The earthquake was widely felt in the southern peninsula and had a maximum MMI VIII in the epicentral region. Most of the intraplate earthquakes occur along preexisting weaknesses, but the potentially seismogenic structures are mostly not exposed at the surface. This study focuses on (1) the structural features in the neighboring area of the epicenter, (2) the distribution of earthquake hypocenter locations during the first 10 days of the aftershock sequence of the Gyeongju earthquake, and (3) the focal mechanism solution of select events to reveal the geometry and kinematics of its causative fault. The earthquake hypocenters in plan view clearly show a linear distribution of N 28°E, which extends about 7 km southwestward from the Yangsan Fault to the Deokcheon Fault. In cross-sectional views along N28°E and perpendicularly, the hypocenters at depths between 11 and 16 km clearly delineate a subsurface fault which has a rupturing size of about 3 ´ 3 km2 and a dip of 78°SE. Based on focal mechanism solutions, the fault acted as dextral strike-slip fault under ENE-WSW compressional stress that has been widely known as the major component of current stress field in and around Korean peninsula. The general trend, N 28°E, of the seismogenic fault slightly differs from the strike of the adjacent NNE-striking Yangsan Fault with an angular difference of 15°. The Yangsan fault is the most prominent dextral strike-slip fault in SE Korea, which can be traced for 170 km with a right-lateral offset of 30 km. The strike-slip movement is well-reported to have occurred during the Paleogene. At that time, probably numerous subsidiary fractures, such as Y-, R-, R'-, and T fractures, in various directions were produced along the Yangsan master fault. It is thus interpreted that a large R

  12. A Tensile Origin for Pulverized Fault Zone Rock

    Science.gov (United States)

    St Julien, R. C.; Griffith, W. A.; Ghaffari, H. O.

    2017-12-01

    The origin of highly fragmented, but lightly strained rocks distributed asymmetrically across major strike slip faults has been enigmatic since their first recognition, yet the explanation has major implications for earthquake physics. These so called "pulverized" rocks are found up to 100m away from the principal slip zone of the San Andreas fault and other strike slip faults around the world. Experiments suggest that rock pulverization occurs at strain rates on the order of 102 s-1, pointing to a coseismic origin; however, strain rates during sub-Rayleigh earthquake rupture propagation 100m from faults is expected to be at least two orders of magnitude smaller than this, leading some to suggest that pulverization occurs during supershear earthquake rupture. Numerical solutions suggest that states of isotropic tension occur in more compliant sides of the fault, and at distances as great as 100m from the fault, as a sub-Rayleigh rupture propagates. We develop a novel modification to the Split-Hopkinson Pressure Bar apparatus wherein an axial compressive pulse produces isotropic radial tension in a disk-shaped rock specimen. We show that under isotropic tension, fragmentation of Westerly Granite occurs at strain rates on the order of 100 s-1, and fragment size scales inversely with strain rate in close agreement with energy-based fragmentation models. Similar experiments on thermally pre-treated Westerly granite specimens demonstrate how pre-existing damage can further reduce strain rates and tensile stresses required for intense fragmentation. Our results solve the strain rate-distance scaling problem between laboratory and field observations of pulverized rocks and also explains the asymmetric distribution of fault rocks. Furthermore, this implies long-term preferred earthquake rupture directivity along major faults where pulverized rocks are found.

  13. 3D Defect Localization on Exothermic Faults within Multi-Layered Structures Using Lock-In Thermography: An Experimental and Numerical Approach.

    Science.gov (United States)

    Bae, Ji Yong; Lee, Kye-Sung; Hur, Hwan; Nam, Ki-Hwan; Hong, Suk-Ju; Lee, Ah-Yeong; Chang, Ki Soo; Kim, Geon-Hee; Kim, Ghiseok

    2017-10-13

    Micro-electronic devices are increasingly incorporating miniature multi-layered integrated architectures. However, the localization of faults in three-dimensional structure remains challenging. This study involved the experimental and numerical estimation of the depth of a thermally active heating source buried in multi-layered silicon wafer architecture by using both phase information from an infrared microscopy and finite element simulation. Infrared images were acquired and real-time processed by a lock-in method. It is well known that the lock-in method can increasingly improve detection performance by enhancing the spatial and thermal resolution of measurements. Operational principle of the lock-in method is discussed, and it is represented that phase shift of the thermal emission from a silicon wafer stacked heat source chip (SSHSC) specimen can provide good metrics for the depth of the heat source buried in SSHSCs. Depth was also estimated by analyzing the transient thermal responses using the coupled electro-thermal simulations. Furthermore, the effects of the volumetric heat source configuration mimicking the 3D through silicon via integration package were investigated. Both the infrared microscopic imaging with the lock-in method and FE simulation were potentially useful for 3D isolation of exothermic faults and their depth estimation for multi-layered structures, especially in packaged semiconductors.

  14. Fluid Flow and Fault Zone Damage in Crystalline Basement Rocks (Ore Mountains Saxony)

    Science.gov (United States)

    Achtziger-Zupančič, P.; Loew, S.; Hiller, A.; Mariethoz, G.

    2015-12-01

    Groundwater flow in fractured basement rocks on aquifer scale and processes involved in the creation of fracture network permeability are poorly understood even though they have been studied for decades. A unique hydrogeological dataset consisting of 1030 discrete inflows (corresponding to preferential groundwater pathways) to the Poehla Ore Mine (Ore Mountains) of the SDAG Wismut has been compiled and quantitatively interpreted. Transmissivities and permeabilities were calculated from discrete and cumulative inflows using analytical equations and numerical groundwater flow models. The Variscan basement at Poehla Mine was modelled in 3-D, covering a volume of 14x4x1 km3 with 14 metamorphosed litho-stratigraphic units and 131 faults separated in 6 main strike directions. Mesoscale fractures mapped at inflows points, i.e. locally conductive fractures, show a weak correlation with fault orientation, and a large orientation scattering, which could be related to small scale stress heterogeneities. Inflow points were spatially correlated with major faults considering two distance criteria. This correlation suggests that mainly NW-SE and NE-SW striking faults are transmissive, which should be critically stressed considering all available data about the regional stress field. The trace length (extent) and width of the core and damage zones of the modelled faults were compiled in order to investigate the flow distribution and permeability profiles in directions perpendicular to fault strike. It can be shown that 90% of all inflows are located in damage zones. The inflows are usually situated within multiple fault zones which overlap each other. Cumulative flow distribution functions within damage zones are non-linear and vary between faults with different orientation. 75-95% of the flow occurs in the inner 50% of the damage zone. Significantly lower flow rates were recognized within most fault cores.

  15. A right to strike?

    Science.gov (United States)

    Jennings, K; Western, G

    1997-07-01

    During 1995, there was a major shift in the United Kingdom in the debate of whether it is right for nurses to strike. The Royal College of Nursing, the former advocate of a non-industrial action policy, moved towards the UNISON position that industrial action is ethical in some circumstances, as well as the necessary thing to do. The authors, both nurses and UNISON officials, look at the reasons for this change and why UNISON's historical position sees industrial action as an effective weapon in defending services, as well as wages and jobs. It can be right to strike.

  16. A bottom-driven mechanism for distributed faulting: Insights from the Gulf of California Rift

    Science.gov (United States)

    Persaud, P.; Tan, E.; Choi, E.; Contreras, J.; Lavier, L. L.

    2017-12-01

    The Gulf of California is a young oblique rift that displays a variation in rifting style along strike. Despite the rapid localization of strain in the Gulf at 6 Ma, the northern rift segment has the characteristics of a wide rift, with broadly distributed extensional strain and small gradients in topography and crustal thinning. Observations of active faulting in the continent-ocean transition of the Northern Gulf show multiple oblique-slip faults distributed in a 200 x 70 km2area developed some time after a westward relocation of the plate boundary at 2 Ma. In contrast, north and south of this broad pull-apart structure, major transform faults accommodate Pacific-North America plate motion. Here we propose that the mechanism for distributed brittle deformation results from the boundary conditions present in the Northern Gulf, where basal shear is distributed between the Cerro Prieto strike-slip fault (southernmost fault of the San Andreas fault system) and the Ballenas Transform fault. We hypothesize that in oblique-extensional settings whether deformation is partitioned in a few dip-slip and strike-slip faults, or in numerous oblique-slip faults may depend on (1) bottom-driven, distributed extension and shear deformation of the lower crust or upper mantle, and (2) the rift obliquity. To test this idea, we explore the effects of bottom-driven shear on the deformation of a brittle elastic-plastic layer with pseudo-three dimensional numerical models that include side forces. Strain localization results when the basal shear is a step-function while oblique-slip on numerous faults dominates when basal shear is distributed. We further investigate how the style of faulting varies with obliquity and demonstrate that the style of faulting observed in the Northern Gulf of California is reproduced in models with an obliquity of 0.7 and distributed basal shear boundary conditions, consistent with the interpreted obliquity and boundary conditions of the study area. Our

  17. Geophysical Characterization of the Hilton Creek Fault System

    Science.gov (United States)

    Lacy, A. K.; Macy, K. P.; De Cristofaro, J. L.; Polet, J.

    2016-12-01

    The Long Valley Caldera straddles the eastern edge of the Sierra Nevada Batholith and the western edge of the Basin and Range Province, and represents one of the largest caldera complexes on Earth. The caldera is intersected by numerous fault systems, including the Hartley Springs Fault System, the Round Valley Fault System, the Long Valley Ring Fault System, and the Hilton Creek Fault System, which is our main region of interest. The Hilton Creek Fault System appears as a single NW-striking fault, dipping to the NE, from Davis Lake in the south to the southern rim of the Long Valley Caldera. Inside the caldera, it splays into numerous parallel faults that extend toward the resurgent dome. Seismicity in the area increased significantly in May 1980, following a series of large earthquakes in the vicinity of the caldera and a subsequent large earthquake swarm which has been suggested to be the result of magma migration. A large portion of the earthquake swarms in the Long Valley Caldera occurs on or around the Hilton Creek Fault splays. We are conducting an interdisciplinary geophysical study of the Hilton Creek Fault System from just south of the onset of splay faulting, to its extension into the dome of the caldera. Our investigation includes ground-based magnetic field measurements, high-resolution total station elevation profiles, Structure-From-Motion derived topography and an analysis of earthquake focal mechanisms and statistics. Preliminary analysis of topographic profiles, of approximately 1 km in length, reveals the presence of at least three distinct fault splays within the caldera with vertical offsets of 0.5 to 1.0 meters. More detailed topographic mapping is expected to highlight smaller structures. We are also generating maps of the variation in b-value along different portions of the Hilton Creek system to determine whether we can detect any transition to more swarm-like behavior towards the North. We will show maps of magnetic anomalies, topography

  18. Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults.

    Science.gov (United States)

    Cowie, P A; Phillips, R J; Roberts, G P; McCaffrey, K; Zijerveld, L J J; Gregory, L C; Faure Walker, J; Wedmore, L N J; Dunai, T J; Binnie, S A; Freeman, S P H T; Wilcken, K; Shanks, R P; Huismans, R S; Papanikolaou, I; Michetti, A M; Wilkinson, M

    2017-03-21

    Many areas of the Earth's crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic 36 Cl measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The 36 Cl data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (10 4  yr; 10 2  km) but over shorter timescales most of the deformation may be accommodated by fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting.

  19. Algab õppus "Saber Strike"

    Index Scriptorium Estoniae

    2014-01-01

    Täna algab Eestis, Lätis ja Leedus Ameerika Ühendriikide Euroopa väekoondise õppus "Saber Strike", mille eesmärk on maaväeüksuste koostöö harjutamine. Õppusest võtab osa üle 2000 kaitseväelase Baltimaadest, USAst, Ühendkuningriigist, Taanist, Norrast, Soomest ja Saksamaalt. Eestist osaleb õppusel ligi 400 kaitseväelast

  20. Hydromechanical heterogeneities of a mature fault zone: impacts on fluid flow.

    Science.gov (United States)

    Jeanne, Pierre; Guglielmi, Yves; Cappa, Frédéric

    2013-01-01

    In this paper, fluid flow is examined for a mature strike-slip fault zone with anisotropic permeability and internal heterogeneity. The hydraulic properties of the fault zone were first characterized in situ by microgeophysical (VP and σc ) and rock-quality measurements (Q-value) performed along a 50-m long profile perpendicular to the fault zone. Then, the local hydrogeological context of the fault was modified to conduct a water-injection test. The resulting fluid pressures and flow rates through the different fault-zone compartments were then analyzed with a two-phase fluid-flow numerical simulation. Fault hydraulic properties estimated from the injection test signals were compared to the properties estimated from the multiscale geological approach. We found that (1) the microgeophysical measurements that we made yield valuable information on the porosity and the specific storage coefficient within the fault zone and (2) the Q-value method highlights significant contrasts in permeability. Fault hydrodynamic behavior can be modeled by a permeability tensor rotation across the fault zone and by a storativity increase. The permeability tensor rotation is linked to the modification of the preexisting fracture properties and to the development of new fractures during the faulting process, whereas the storativity increase results from the development of micro- and macrofractures that lower the fault-zone stiffness and allows an increased extension of the pore space within the fault damage zone. Finally, heterogeneities internal to the fault zones create complex patterns of fluid flow that reflect the connections of paths with contrasting properties. © 2013, The Author(s). Ground Water © 2013, National Ground Water Association.

  1. Origins of oblique-slip faulting during caldera subsidence

    Science.gov (United States)

    Holohan, Eoghan P.; Walter, Thomas R.; Schöpfer, Martin P. J.; Walsh, John J.; van Wyk de Vries, Benjamin; Troll, Valentin R.

    2013-04-01

    Although conventionally described as purely dip-slip, faults at caldera volcanoes may have a strike-slip displacement component. Examples occur in the calderas of Olympus Mons (Mars), Miyakejima (Japan), and Dolomieu (La Reunion). To investigate this phenomenon, we use numerical and analog simulations of caldera subsidence caused by magma reservoir deflation. The numerical models constrain mechanical causes of oblique-slip faulting from the three-dimensional stress field in the initial elastic phase of subsidence. The analog experiments directly characterize the development of oblique-slip faulting, especially in the later, non-elastic phases of subsidence. The combined results of both approaches can account for the orientation, mode, and location of oblique-slip faulting at natural calderas. Kinematically, oblique-slip faulting originates to resolve the following: (1) horizontal components of displacement that are directed radially toward the caldera center and (2) horizontal translation arising from off-centered or "asymmetric" subsidence. We informally call these two origins the "camera iris" and "sliding trapdoor" effects, respectively. Our findings emphasize the fundamentally three-dimensional nature of deformation during caldera subsidence. They hence provide an improved basis for analyzing structural, geodetic, and geophysical data from calderas, as well as analogous systems, such as mines and producing hydrocarbon reservoirs.

  2. Electrical resistivity variations associated with earthquakes on the san andreas fault.

    Science.gov (United States)

    Mazzella, A; Morrison, H F

    1974-09-06

    A 24 percent precursory change in apparent electrical resistivity was observed before a magnitude 3.9 earthquake of strike-slip nature on the San Andreas fault in central California. The experimental configuration and numerical calculations suggest that the change is associated with a volume at depth rather than some near-surface phenomenon. The character and duration of the precursor period agree well with those of other earthquake studies and support a dilatant earthquake mechanism model.

  3. Synthesis of Near-fault Ground Motion Using a Hybrid Method of Stochastic and Theoretical Green’s Functions

    Directory of Open Access Journals (Sweden)

    Wu Shuanglan

    2016-10-01

    Full Text Available The effect of near-fault ground displacement is a significant factor when structures straddle a fault, because the fault produces both static step-like deformations and dynamic pulse-like ground motions. It has been observed that the static displacements measured up to 10 m and strong ground motion velocity pulses exceed 100 cm/s. As there is no concrete method for the seismic design of near-fault structures based on earthquake-induced fault displacement, the numerical simulation of near-fault ground motions is of great significance. In this paper, we describe a hybrid method combining stochastic and theoretical Green’s functions for synthesizing near-fault ground motions. Our approach considers the complete waveforms (far-, intermediate-, and near-field terms of both the dynamic and static terms. To demonstrate the hybrid method, two simple examples of strike-slip and dip-slip fault models are simulated. The results exhibited dynamic displacement with the fling-step of near-fault movement. Furthermore, the 1999 Chi-Chi earthquake in Taiwan is also simulated, and the results showed good agreement with the observed recordings. Thus, the proposed method is a useful tool for evaluating near-fault ground motions for designing bridges and other structures.

  4. Research on Line Patrol Strategy of 110kV Transmission Line after Lightning Strike

    Directory of Open Access Journals (Sweden)

    Li Mingjun

    2016-01-01

    Full Text Available Lightning faults occupy in the majority of instantaneous fault and reclosing can usually be successful, so power supply can be restored without immediate patrol in many cases. Firstly, this paper introduces the lightning fault positioning and identifying method. Then test electrical performance of insulators after lightning strike from 110kV lines. Data shows that lightning strike has little effect on the electric performance of insulator. Finally, illustrating disposal process of the 110 kV transmission line after lightning fault, certifying that the power supply reliability be ensured without line patrol.

  5. The Sorong Fault Zone, Indonesia: Mapping a Fault Zone Offshore

    Science.gov (United States)

    Melia, S.; Hall, R.

    2017-12-01

    The Sorong Fault Zone is a left-lateral strike-slip fault zone in eastern Indonesia, extending westwards from the Bird's Head peninsula of West Papua towards Sulawesi. It is the result of interactions between the Pacific, Caroline, Philippine Sea, and Australian Plates and much of it is offshore. Previous research on the fault zone has been limited by the low resolution of available data offshore, leading to debates over the extent, location, and timing of movements, and the tectonic evolution of eastern Indonesia. Different studies have shown it north of the Sula Islands, truncated south of Halmahera, continuing to Sulawesi, or splaying into a horsetail fan of smaller faults. Recently acquired high resolution multibeam bathymetry of the seafloor (with a resolution of 15-25 meters), and 2D seismic lines, provide the opportunity to trace the fault offshore. The position of different strands can be identified. On land, SRTM topography shows that in the northern Bird's Head the fault zone is characterised by closely spaced E-W trending faults. NW of the Bird's Head offshore there is a fold and thrust belt which terminates some strands. To the west of the Bird's Head offshore the fault zone diverges into multiple strands trending ENE-WSW. Regions of Riedel shearing are evident west of the Bird's Head, indicating sinistral strike-slip motion. Further west, the ENE-WSW trending faults turn to an E-W trend and there are at least three fault zones situated immediately south of Halmahera, north of the Sula Islands, and between the islands of Sanana and Mangole where the fault system terminates in horsetail strands. South of the Sula islands some former normal faults at the continent-ocean boundary with the North Banda Sea are being reactivated as strike-slip faults. The fault zone does not currently reach Sulawesi. The new fault map differs from previous interpretations concerning the location, age and significance of different parts of the Sorong Fault Zone. Kinematic

  6. Global strike hypersonic weapons

    Science.gov (United States)

    Lewis, Mark J.

    2017-11-01

    Beginning in the 1940's, the United States has pursued the development of hypersonic technologies, enabling atmospheric flight in excess of five times the speed of sound. Hypersonic flight has application to a range of military and civilian applications, including commercial transport, space access, and various weapons and sensing platforms. A number of flight tests of hypersonic vehicles have been conducted by countries around the world, including the United States, Russia, and China, that could lead the way to future hypersonic global strike weapon systems. These weapons would be especially effective at penetrating conventional defenses, and could pose a significant risk to national security.

  7. Current Microearthquake Activity on the Large Pärvie Endglacial Fault System, Northern Sweden

    Science.gov (United States)

    Lindblom, E.; Lund, B.; Tryggvason, A.; Uski, M.; Juhlin, C.; Bodvarsson, R.; Kvaerna, T.

    2011-12-01

    The Pärvie fault is one of the largest known endglacial faults in the world. It is situated in northernmost Sweden and extends for over 160 km in a northeastward direction. The fault exhibits reverse faulting throw of more than 10 m and based on studies of Quaternary deposits, landslides and liquefaction structures it is inferred to have ruptured as a one-step event at the time of deglaciation in the area, approximately 10,000 years ago. An earthquake of this size would have had a magnitude of approximately 8. The mechanisms driving the endglacial faults are still not well understood. However, knowledge of the fault geometry at depth would significantly contribute to the understanding. In a seismological study of the Pärvie fault we have acquired both a 23 km long seismic reflection profile across the center of the fault, and deployed eight temporary seismic stations in the vicinity of the fault. The results of the reflection seismic processing images the fault system from the near surface down to about 2-3 km depth. The profile crosses three surface mapped faults where the westernmost, main fault strand, is dipping about 50 degrees to the east, the middle fault dipping 75 degrees east and the easternmost fault dipping 60 degrees to the west. The eight temporary seismic stations have recorded microearthquakes together with the six northernmost permanent stations of the Swedish National Seismic Network and a collaborating Finnish station. The seismic stations have recorded numerous small events, most of which are mining induced microearthquakes from the nearby Kiruna and Malmberget iron ore mines. About 800 microearthquakes are detected from the vicinity of the Pärvie fault system. Based on velocity structures estimated using 3D local earthquake tomography we will present locations, magnitudes and focal mechanisms of the events. The events are concentrated to the east side of the surface trace of the main Pärvie fault and spread along its whole north

  8. Signature of dislocations and stacking faults of face-centred cubic nanocrystals in coherent X-ray diffraction patterns: a numerical study.

    Science.gov (United States)

    Dupraz, Maxime; Beutier, Guillaume; Rodney, David; Mordehai, Dan; Verdier, Marc

    2015-06-01

    Crystal defects induce strong distortions in diffraction patterns. A single defect alone can yield strong and fine features that are observed in high-resolution diffraction experiments such as coherent X-ray diffraction. The case of face-centred cubic nanocrystals is studied numerically and the signatures of typical defects close to Bragg positions are identified. Crystals of a few tens of nanometres are modelled with realistic atomic potentials and 'relaxed' after introduction of well defined defects such as pure screw or edge dislocations, or Frank or prismatic loops. Diffraction patterns calculated in the kinematic approximation reveal various signatures of the defects depending on the Miller indices. They are strongly modified by the dissociation of the dislocations. Selection rules on the Miller indices are provided, to observe the maximum effect of given crystal defects in the initial and relaxed configurations. The effect of several physical and geometrical parameters such as stacking fault energy, crystal shape and defect position are discussed. The method is illustrated on a complex structure resulting from the simulated nanoindentation of a gold nanocrystal.

  9. Influence of faults on groundwater flow and transport at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Cohen, Andrew J.B.; Sitar, Nicholas

    1999-01-01

    Numerical simulations of groundwater flow at Yucca Mountain, Nevada are used to investigate how faults influence groundwater flow pathways and regional-scale macrodispersion. The 3-D model has a unique grid block discretization that facilitates the accurate representation of the complex geologic structure present in faulted formations. Each hydrogeologic layer is discretized into a single layer of irregular and dipping grid blocks, and faults are discretized such that they are laterally continuous and varied in displacement varies along strike. In addition, the presence of altered fault zones is explicitly modeled, as appropriate. Simulations show that upward head gradients can be readily explained by the geometry of hydrogeologic layers, the variability of layer permeabilities, and the presence of permeable fault zones or faults with displacement only, not necessarily by upwelling from a deep aquifer. Large-scale macrodispersion results from the vertical and lateral diversion of flow near the contact of high- and low-permeability layers at faults, and from upward flow within high-permeability fault zones. Conversely, large-scale channeling can occur as a result of groundwater flow into areas with minimal fault displacement. Contaminants originating at the water table can flow in a direction significantly different from that of the water table gradient, and isolated zones of contaminants can occur at the water table downgradient. By conducting both 2-D and 3-D simulations, we show that the 2-D cross-sectional models traditionally used to examine flow in faulted formations may not be appropriate. In addition, the influence of a particular type of fault cannot be generalized; depending on the location where contaminants enter the saturated zone, faults may either enhance or inhibit vertical dispersion

  10. Impulse of a Kendo Strike

    Directory of Open Access Journals (Sweden)

    Masahiro Abe

    2012-06-01

    Full Text Available An expert swordsman struck a target with a kendo sword. The velocity and force of the strike were measured. The relationship between the strike velocity, impact force and effective mass of the sword was investigated. It was shown that the effective mass of the sword remains constant for typical strike velocities.

  11. The public's attitude towards strike action by healthcare workers and ...

    African Journals Online (AJOL)

    The strength of the associations was determined by Cramer's V. Results. Results revealed strong opinions among the population regarding strikes, numerous misapprehensions when it comes to striking and rights, a poor awareness of other healthcare-related rights and the perception of poor treatment at public hospitals.

  12. 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.

  13. Neotectonic history and geometric segmentation of the Campo Grande fault: A major structure bounding in the Hueco basin, trans-Pecos Texas

    International Nuclear Information System (INIS)

    Collins, E.W.; Raney, J.A.

    1991-01-01

    The northwest-striking Campo Grande fault of trans-Pecos Texas has a surface trace of about 45 km. It divides the downthrown, central part of the Hueco basin, which contains as much as 2,850 m of Cenozoic fill, from the shallower northeastern flank that has 150-300 m of fill. This normal fault is composed of three main en echelon segments, which are composed of numerous en echelon fault strands that are 1.5-10 km long at the surface. These strands strike N25 degree-75 degree W and dip 60 degree-90 degree southwestward. Erosion-resistant calcrete (stage 4-5) at the surface aids in preserving scarp heights of between 1.5 and 11.5 m and scarp slopes of between 4 degree and 17 degree. Surface analysis of faulted upper Tertiary and Quaternary units along the southeastern Campo Grande fault segment indicates that successively younger units have less displacement. The last surface rupture was late Pleistocene. On the hanging wall of one fault strand, faulted calcic soil horizons (stage 3) as much as 1 m thick with vertical separations of 1-2 m indicate at least five episodes of fault movement, sediment deposition, and surface stabilization since middle Pleistocene time. The maximum vertical offset during the latest surface rupture was about 1-1.5 m

  14. Neotectonic history and geometric segmentation of the Campo Grande fault: A major structure bounding the Hueco basin, trans-Pecos Texas

    Science.gov (United States)

    Collins, Edward W.; Raney, Jay A.

    1991-05-01

    The northwest-striking Campo Grande fault of trans-Pecos Texas has a surface trace of about 45km. It divides the downthrown, central part of the Hueco basin, which contains as much as 2850m of Cenozoic fill, from the shallower northeastern flank that has 150-300m of fill. This normal fault is composed of three main en echelon segments, which are composed of numerous en echelon fault strands that are 1.5-10 km long at the surface. These strands strike N25°-75°W and dip 60°-90° southwestward. Erosion-resistant calcrete (stage IV-V) at the surface aids in preserving scarp heights of between 1.5 and 11.5m and scarp slopes of between 4° and 17°. Surface analysis of faulted upper Tertiary and Quaternary units along the southeastern Campo Grande fault segment indicates that successively younger units have less displacement. The last surface rupture was late Pleistocene. On the hanging wall of one fault strand, faulted calcic soil horizons (stage III) as much as 1m thick with vertical separations of 1-2 m indicate at least five episodes of fault movement, sediment deposition, and surface stabilization since middle Pleistocene time. The maximum vertical offset during the latest surface rupture was about 1-1.5m.

  15. Three dimensional modelling of earthquake rupture cycles on frictional faults

    Science.gov (United States)

    Simpson, Guy; May, Dave

    2017-04-01

    We are developing an efficient MPI-parallel numerical method to simulate earthquake sequences on preexisting faults embedding within a three dimensional viscoelastic half-space. We solve the velocity form of the elasto(visco)dynamic equations using a continuous Galerkin Finite Element Method on an unstructured pentahedral mesh, which thus permits local spatial refinement in the vicinity of the fault. Friction sliding is coupled to the viscoelastic solid via rate- and state-dependent friction laws using the split-node technique. Our coupled formulation employs a picard-type non-linear solver with a fully implicit, first order accurate time integrator that utilises an adaptive time step that efficiently evolves the system through multiple seismic cycles. The implementation leverages advanced parallel solvers, preconditioners and linear algebra from the Portable Extensible Toolkit for Scientific Computing (PETSc) library. The model can treat heterogeneous frictional properties and stress states on the fault and surrounding solid as well as non-planar fault geometries. Preliminary tests show that the model successfully reproduces dynamic rupture on a vertical strike-slip fault in a half-space governed by rate-state friction with the ageing law.

  16. The role of E–W basement faults in the Mesozoic geodynamic ...

    Indian Academy of Sciences (India)

    Dorra Tanfous Amri

    2017-10-10

    Oct 10, 2017 ... and occurred only along main strike-slip faults. In addition, seismic lines show that Triassic rocks are .... ated anticlines are due to an E–W strike-slip fault, whereas Zargouni (1985), Boukadi (1994), Zouari ...... right–lateral oblique–slip features such as the Gafsa fault (Boukadi and Bédir 1996; Hlaiem 1999; ...

  17. 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.

  18. 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.

  19. Faults architecture and growth in clay-limestone alternation. Examples in the S-E Basin alternations (France) and numerical modeling; Architecture et croissance des failles dans les alternances argilo-calcaires. Exemples dans les alternances du Bassin du Sud-Est (France) et modelisation numerique

    Energy Technology Data Exchange (ETDEWEB)

    Roche, Vincent

    2011-10-28

    The following work has been carried out in the framework of the studies conducted by IRSN in support of its safety evaluation of the geological disposal programme of high and intermediate level, long-lived radioactive waste. Such a disposal is planned to be hosted by the Callovian-Oxfordian indurate clay formation between two limestone formations in eastern Paris basin, France. Hypothetical faults may cross-cut this layered section, decreasing the clay containment ability by creating preferential pathways for radioactive solute towards limestones. This study aims at characterising the fault architecture and the normal fault growth in clay/limestone layered sections. Structural analysis and displacement profiles have been carried out in normal faults crossing several decimetres to metre thick sedimentary alternations in the South-Eastern Basin (France) and petrophysical properties have been determined for each layer. The studied faults are simple fault planes or complex fault zones showing are significantly controlled by the layering. The analysis of the fault characteristics and the results obtained on numerical models enlighten several processes such as fault nucleation, fault restriction, and fault growth through layered section. Some studied faults nucleated in the limestone layers, without using pre-existing fractures such as joints, and according to our numerical analysis, a strong stiffness, a low strength contrast between the limestone and the clay layer, and/or s a greater thickness of the clay layer are conditions which favour nucleation of faults in limestone. The range of mechanical properties leading to the fault nucleation in one layer type or another was investigated using a 3D modelling approach. After its nucleation, the fault propagates within a homogeneous medium with a constant displacement gradient until its vertical propagation is stopped by a restrictor. The evidenced restrictors are limestone-clay interfaces or faults in clays, sub

  20. Precision Strike Annual Programs Review

    Science.gov (United States)

    2009-03-11

    Damage Area*• GPS / INS Navigation + SAL Terminal • Precise əm CEP • Low Probability of Collateral Damage • GPS Extends Glide Range to 10+km • Agile...Page 311 Mar 09 Unclassified Unclassified Viper Strike Lineage Viper Strike SAL Seeker Proof of Principle Demos I & II Hunter-Viper Strike Quick...Information Management • CCA - Clinger Cohen Act • RIT- Rapid Improvement Team • BMMP – Business Management Modernization Program • BTA/ERAM – Business

  1. A PHYSICAL MODEL OF THE EFFECT OF A SHALLOW WEAK LAYER ON STRONG GROUND MOTION FOR STRIKE-SLIP RUPTURES

    Energy Technology Data Exchange (ETDEWEB)

    JAMES N. BRUNE AND ABDOLRASOOL ANOOSHEHPOOR

    1998-02-23

    We report results of foam-rubber modeling of the effect of a shallow weak layer on ground motion from strike-slip ruptures. Computer modeling of strong ground motion from strike-slip earthquakes has involved somewhat arbitrary assumptions about the nature of slip along the shallow part of the fault (e.g., fixing the slip to be zero along the upper 2 kilometers of the fault plane) in order to match certain strong motion accelerograms. Most modeling studies of earthquake strong ground motion have used what is termed kinematic dislocation modeling. In kinematic modeling the time function for slip on the fault is prescribed, and the response of the layered medium is calculated. Unfortunately, there is no guarantee that the model and the prescribed slip are physically reasonable unless the true nature of the medium and its motions are known ahead of time. There is good reason to believe that in many cases faults are weak along the upper few kilometers of the fault zone and may not be able to maintain high levels of shear strain required for high dynamic energy release during earthquakes. Physical models of faulting, as distinct from numerical or mathematical models, are guaranteed to obey static and dynamic mechanical laws. Foam-rubber modeling studies have been reported in a number of publications. The object of this paper is to present results of physical modeling using a shallow weak layer, in order to verify the physical basis for assuming a long rise time and a reduced high frequency pulse for the slip on the shallow part of faults. It appears a 2-kilometer deep, weak zone along strike-slip faults could indeed reduce the high frequency energy radiated from shallow slip, and that this effect can best be represented by superimposing a small amplitude, short rise-time pulse at the onset of a much longer rise-time slip. A weak zone was modeled by inserting weak plastic layers of a few inches in thickness into the foam rubber model. For the 15 cm weak zone the average

  2. Fault on–off versus coseismic fluids reaction

    Directory of Open Access Journals (Sweden)

    C. Doglioni

    2014-11-01

    Full Text Available The fault activation (fault on interrupts the enduring fault locking (fault off and marks the end of a seismic cycle in which the brittle-ductile transition (BDT acts as a sort of switch. We suggest that the fluid flow rates differ during the different periods of the seismic cycle (interseismic, pre-seismic, coseismic and post-seismic and in particular as a function of the tectonic style. Regional examples indicate that tectonic-related fluids anomalies depend on the stage of the tectonic cycle and the tectonic style. Although it is difficult to model an increasing permeability with depth and several BDT transitions plus independent acquicludes may occur in the crust, we devised the simplest numerical model of a fault constantly shearing in the ductile deeper crust while being locked in the brittle shallow layer, with variable homogeneous permeabilities. The results indicate different behaviors in the three main tectonic settings. In tensional tectonics, a stretched band antithetic to the normal fault forms above the BDT during the interseismic period. Fractures close and fluids are expelled during the coseismic stage. The mechanism reverses in compressional tectonics. During the interseismic stage, an over-compressed band forms above the BDT. The band dilates while rebounding in the coseismic stage and attracts fluids locally. At the tip lines along strike-slip faults, two couples of subvertical bands show different behavior, one in dilation/compression and one in compression/dilation. This deformation pattern inverts during the coseismic stage. Sometimes a pre-seismic stage in which fluids start moving may be observed and could potentially become a precursor.

  3. Anisotropy of permeability in faulted porous sandstones

    Science.gov (United States)

    Farrell, N. J. C.; Healy, D.; Taylor, C. W.

    2014-06-01

    Studies of fault rock permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of porous sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host rock porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (σ1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted porous sandstone by compaction and reorganisation of grains through shearing and cataclasis.

  4. Fault linkage and continental breakup

    Science.gov (United States)

    Cresswell, Derren; Lymer, Gaël; Reston, Tim; Stevenson, Carl; Bull, Jonathan; Sawyer, Dale; Morgan, Julia

    2017-04-01

    The magma-poor rifted margin off the west coast of Galicia (NW Spain) has provided some of the key observations in the development of models describing the final stages of rifting and continental breakup. In 2013, we collected a 68 x 20 km 3D seismic survey across the Galicia margin, NE Atlantic. Processing through to 3D Pre-stack Time Migration (12.5 m bin-size) and 3D depth conversion reveals the key structures, including an underlying detachment fault (the S detachment), and the intra-block and inter-block faults. These data reveal multiple phases of faulting, which overlap spatially and temporally, have thinned the crust to between zero and a few km thickness, producing 'basement windows' where crustal basement has been completely pulled apart and sediments lie directly on the mantle. Two approximately N-S trending fault systems are observed: 1) a margin proximal system of two linked faults that are the upward extension (breakaway faults) of the S; in the south they form one surface that splays northward to form two faults with an intervening fault block. These faults were thus demonstrably active at one time rather than sequentially. 2) An oceanward relay structure that shows clear along strike linkage. Faults within the relay trend NE-SW and heavily dissect the basement. The main block bounding faults can be traced from the S detachment through the basement into, and heavily deforming, the syn-rift sediments where they die out, suggesting that the faults propagated up from the S detachment surface. Analysis of the fault heaves and associated maps at different structural levels show complementary fault systems. The pattern of faulting suggests a variation in main tectonic transport direction moving oceanward. This might be interpreted as a temporal change during sequential faulting, however the transfer of extension between faults and the lateral variability of fault blocks suggests that many of the faults across the 3D volume were active at least in part

  5. Hydrothermal Upflow, Serpentinization and Talc Alteration Associated with a High Angle Normal Fault Cutting an Oceanic Detachment, Northern Apennines, Italy

    Science.gov (United States)

    Alt, J.; Crispini, L.; Gaggero, L.; Shanks, W. C., III; Gulbransen, C.; Lavagnino, G.

    2017-12-01

    Normal faults cutting oceanic core complexes are observed at the seafloor and through geophysics, and may act as flow pathways for hydrothermal fluids, but we know little about such faults in the subsurface. We present bulk rock geochemistry and stable isotope data for a fault that acted as a hydrothermal upflow zone in a seafloor ultramafic-hosted hydrothermal system in the northern Apennines, Italy. Peridotites were exposed on the seafloor by detachment faulting, intruded by MORB gabbros, and are overlain by MORB lavas and pelagic sediments. North of the village of Reppia are fault shear zones in serpentinite, oriented at a high angle to the detachment surface and extending 300 m below the paleo-seafloor. The paleo-seafloor strikes roughly east-west, dipping 30˚ to the north. At depth the fault zone occurs as an anticlinal form plunging 40˚ to the west. A second fault strikes approximately north-south, with a near vertical dip. The fault rock outcrops as reddish weathered talc + sulfide in 0.1-2 m wide anastomosing bands, with numerous splays. Talc replaces serpentinite in the fault rocks, and the talc rocks are enriched in Si, metals (Fe, Cu, Pb), Light Rare Earth Elements (LREE), have variable Eu anomalies, and have low Mg, Cr and Ni contents. In some cases gabbro dikes are associated with talc-alteration and may have enhanced fluid flow. Sulfide from a fault rock has d34S=5.7‰. The mineralogy and chemistry of the fault rocks indicate that the fault acted as the upflow pathway for high-T black-smoker type fluids. Traverses away from the fault (up to 1 km) and with depth below the seafloor (up to 500 m) reveal variable influences of hydrothermal fluids, but there are no consistent trends with distance. Background serpentinites 500 m beneath the paleoseafloor have LREE depleted trends. Other serpentinites exhibit correlations of LREE with HFSE as the result of melt percolation, but there is significant scatter, and hydrothermal effects include LREE enrichment

  6. Seismological Studies for Tensile Faults

    Directory of Open Access Journals (Sweden)

    Gwo-Bin Ou

    2008-01-01

    Full Text Available A shear slip fault, an equivalence of a double couple source, has often been assumed to be a kinematic source model in ground motion simulation. Estimation of seismic moment based on the shear slip model indicates the size of an earthquake. However, if the dislocation of the hanging wall relative to the footwall includes not only a shear slip tangent to the fault plane but also expansion and compression normal to the fault plane, the radiating seismic waves will feature differences from those out of the shear slip fault. Taking account of the effects resulting from expansion and compression to a fault plane, we can resolve the tension and pressure axes as well as the fault plane solution more exactly from ground motions than previously, and can evaluate how far a fault zone opens or contracts during a developing rupture. In addition to a tensile angle and Poisson¡¦s ratio for the medium, a tensile fault with five degrees of freedom has been extended from the shear slip fault with only three degrees of freedom, strike, dip, and slip.

  7. Numerical models of pore pressure and stress changes along basement faults due to wastewater injection: Applications to the 2014 Milan, Kansas Earthquake

    Science.gov (United States)

    Hearn, Elizabeth H.; Koltermann, Christine; Rubinstein, Justin R.

    2018-01-01

    We have developed groundwater flow models to explore the possible relationship between wastewater injection and the 12 November 2014 Mw 4.8 Milan, Kansas earthquake. We calculate pore pressure increases in the uppermost crust using a suite of models in which hydraulic properties of the Arbuckle Formation and the Milan earthquake fault zone, the Milan earthquake hypocenter depth, and fault zone geometry are varied. Given pre‐earthquake injection volumes and reasonable hydrogeologic properties, significantly increasing pore pressure at the Milan hypocenter requires that most flow occur through a conductive channel (i.e., the lower Arbuckle and the fault zone) rather than a conductive 3‐D volume. For a range of reasonable lower Arbuckle and fault zone hydraulic parameters, the modeled pore pressure increase at the Milan hypocenter exceeds a minimum triggering threshold of 0.01 MPa at the time of the earthquake. Critical factors include injection into the base of the Arbuckle Formation and proximity of the injection point to a narrow fault damage zone or conductive fracture in the pre‐Cambrian basement with a hydraulic diffusivity of about 3–30 m2/s. The maximum pore pressure increase we obtain at the Milan hypocenter before the earthquake is 0.06 MPa. This suggests that the Milan earthquake occurred on a fault segment that was critically stressed prior to significant wastewater injection in the area. Given continued wastewater injection into the upper Arbuckle in the Milan region, assessment of the middle Arbuckle as a hydraulic barrier remains an important research priority.

  8. 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.

  9. 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.

  10. Paleoseismological investigations on a slow-moving active fault in central Anatolia, Tecer Fault, Sivas

    Directory of Open Access Journals (Sweden)

    Husnu Serdar Akyuz

    2013-01-01

    Full Text Available Tecer Fault is a N60˚-70˚E-trending, left-lateral, strike-slip fault to the south of the town of Sivas, Turkey. This fault is considered as the eastward continuation of Deliler Fault, which was classified as a probably active, left-lateral fault on the Active Fault Map of Turkey. We investigated the field characteristics and paleoseismic history of Tecer Fault in detail. After analyzing aerial photographs and satellite images, we mapped the exact fault trace on a 1/25,000 scale topographic map, between the towns of Deliilyas in southwest and Bogazdere in northeast. Tecer Fault is characterized by morphological features such as offset streams and gullies, linear depressions and scarps, and elongated hills. Four paleoseismological trenches were excavated on the northeastern extent of the fault. Two past earthquakes were identified in these trenches, and the dates of the collected charcoal samples suggested that the first of these earthquakes occurred about 8000 B.C. while the more recent event took place around 3500 B.C. Field observations and paleoseismic data indicate that Tecer Fault is an active, pure sinistral, strike-slip fault, and that there is about a 4500 years time span between the two earthquakes. It is also clear that there has not been any surface-ruptured faulting over the last 800 years. Compared with the earthquake characteristics of other strike-slip fault zones in Turkey in terms of time-slip relations, the slip rate can be estimated as about 1 mm/yr on Tecer Fault.

  11. Active faults pattern and interplay in the Azerbaijan region (NW Iran)

    Science.gov (United States)

    Faridi, M.; Burg, J.-P.; Nazari, H.; Talebian, M.; Ghorashi, M.

    2017-07-01

    Northwest Iran is dominated by two main sets of active strike slip faults that accommodate oblique convergence between the Arabian and Iranian Plates. The best known are the right-lateral North-Tabriz, Qoshadagh, Maragheh and Zagros (Main Recent) strike slip Faults. This work reports that these dominant NW-SE to E-W striking faults are conjugate to smaller, NNE-SSW striking, left-lateral faults with minor dip slip component. All of these active faults displace Precambrian rock units, which suggests that they root in the crystalline basement of the NW Iranian microcontinent. Coulomb stress variance during co-seismic rupture along one of these faults may cause reactivation of the other faults. The minor set of left-lateral fault is therefore important to introduce in seismic risk assessment.

  12. Seismic evidence of conjugate normal faulting: The 1994 Devil Canyon earthquake sequence near Challis, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Suzette M. [Boise State Univ., ID (United States)

    1994-08-01

    Aftershock hypocenters of the 1984 Devil Canyon, Idaho earthquake indicate the sequence was associated with conjugate normal faulting on two northwest-striking normal faults that bound the Warm Spring Creek graben.

  13. Faults Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Through the study of faults and their effects, much can be learned about the size and recurrence intervals of earthquakes. Faults also teach us about crustal...

  14. Geological Effects on Lightning Strike Distributions

    KAUST Repository

    Berdahl, J. Scott

    2016-05-16

    Recent advances in lightning detection networks allow for detailed mapping of lightning flash locations. Longstanding rumors of geological influence on cloud-to-ground (CG) lightning distribution and recent commercial claims based on such influence can now be tested empirically. If present, such influence could represent a new, cheap and efficient geophysical tool with applications in mineral, hydrothermal and oil exploration, regional geological mapping, and infrastructure planning. This project applies statistical analysis to lightning data collected by the United States National Lightning Detection Network from 2006 through 2015 in order to assess whether the huge range in electrical conductivities of geological materials plays a role in the spatial distribution of CG lightning. CG flash densities are mapped for twelve areas in the contiguous United States and compared to elevation and geology, as well as to the locations of faults, railroads and tall towers including wind turbines. Overall spatial randomness is assessed, along with spatial correlation of attributes. Negative and positive polarity lightning are considered separately and together. Topography and tower locations show a strong influence on CG distribution patterns. Geology, faults and railroads do not. This suggests that ground conductivity is not an important factor in determining lightning strike location on scales larger than current flash location accuracies, which are generally several hundred meters. Once a lightning channel is established, however, ground properties at the contact point may play a role in determining properties of the subsequent stroke.

  15. Secondary Fault Activity of the North Anatolian Fault near Avcilar, Southwest of Istanbul: Evidence from SAR Interferometry Observations

    Directory of Open Access Journals (Sweden)

    Faqi Diao

    2016-10-01

    Full Text Available Strike-slip faults may be traced along thousands of kilometers, e.g., the San Andreas Fault (USA or the North Anatolian Fault (Turkey. A closer look at such continental-scale strike faults reveals localized complexities in fault geometry, associated with fault segmentation, secondary faults and a change of related hazards. The North Anatolian Fault displays such complexities nearby the mega city Istanbul, which is a place where earthquake risks are high, but secondary processes are not well understood. In this paper, long-term persistent scatterer interferometry (PSI analysis of synthetic aperture radar (SAR data time series was used to precisely identify the surface deformation pattern associated with the faulting complexity at the prominent bend of the North Anatolian Fault near Istanbul city. We elaborate the relevance of local faulting activity and estimate the fault status (slip rate and locking depth for the first time using satellite SAR interferometry (InSAR technology. The studied NW-SE-oriented fault on land is subject to strike-slip movement at a mean slip rate of ~5.0 mm/year and a shallow locking depth of <1.0 km and thought to be directly interacting with the main fault branch, with important implications for tectonic coupling. Our results provide the first geodetic evidence on the segmentation of a major crustal fault with a structural complexity and associated multi-hazards near the inhabited regions of Istanbul, with similarities also to other major strike-slip faults that display changes in fault traces and mechanisms.

  16. Differentiating simple and composite tectonic landscapes using numerical fault slip modeling with an example from the south central Alborz Mountains, Iran

    KAUST Repository

    Landgraf, A.

    2013-09-01

    The tectonically driven growth of mountains reflects the characteristics of the underlying fault systems and the applied tectonic forces. Over time, fault networks might be relatively static, but stress conditions could change and result in variations in fault slip orientation. Such a tectonic landscape would transition from a “simple” to a “composite” state: the topography of simple landscapes is correlated with a single set of tectonic boundary conditions, while composite landscapes contain inherited topography due to earlier deformation under different boundary conditions. We use fault interaction modeling to compare vertical displacement fields with topographic metrics to differentiate the two types of landscapes. By successively rotating the axis of maximum horizontal stress, we produce a suite of vertical displacement fields for comparison with real landscapes. We apply this model to a transpressional duplex in the south central Alborz Mountains of Iran, where NW oriented compression was superseded by neotectonic NE compression. The consistency between the modeled displacement field and real landforms indicates that the duplex topography is mostly compatible with the modern boundary conditions, but might include a small remnant from the earlier deformation phase. Our approach is applicable for various tectonic settings and represents an approach to identify the changing boundary conditions that produce composite landscapes. It may be particularly useful for identifying changes that occurred in regions where river profiles may no longer record a signal of the change or where the spatial pattern of uplift is complex.

  17. Tsunami simulations of the 1867 Virgin Island earthquake: Constraints on epicenter location and fault parameters

    Science.gov (United States)

    Barkan, Roy; ten Brink, Uri S.

    2010-01-01

    The 18 November 1867 Virgin Island earthquake and the tsunami that closely followed caused considerable loss of life and damage in several places in the northeast Caribbean region. The earthquake was likely a manifestation of the complex tectonic deformation of the Anegada Passage, which cuts across the Antilles island arc between the Virgin Islands and the Lesser Antilles. In this article, we attempt to characterize the 1867 earthquake with respect to fault orientation, rake, dip, fault dimensions, and first tsunami wave propagating phase, using tsunami simulations that employ high-resolution multibeam bathymetry. In addition, we present new geophysical and geological observations from the region of the suggested earthquake source. Results of our tsunami simulations based on relative amplitude comparison limit the earthquake source to be along the northern wall of the Virgin Islands basin, as suggested by Reid and Taber (1920), or on the carbonate platform north of the basin, and not in the Virgin Islands basin, as commonly assumed. The numerical simulations suggest the 1867 fault was striking 120°–135° and had a mixed normal and left-lateral motion. First propagating wave phase analysis suggests a fault striking 300°–315° is also possible. The best-fitting rupture length was found to be relatively small (50 km), probably indicating the earthquake had a moment magnitude of ∼7.2. Detailed multibeam echo sounder surveys of the Anegada Passage bathymetry between St. Croix and St. Thomas reveal a scarp, which cuts the northern wall of the Virgin Islands basin. High-resolution seismic profiles further indicate it to be a reasonable fault candidate. However, the fault orientation and the orientation of other subparallel faults in the area are more compatible with right-lateral motion. For the other possible source region, no clear disruption in the bathymetry or seismic profiles was found on the carbonate platform north of the basin.

  18. Continental United States Hurricane Strikes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Continental U.S. Hurricane Strikes Poster is our most popular poster which is updated annually. The poster includes all hurricanes that affected the U.S. since...

  19. Fault-tolerant design

    CERN Document Server

    Dubrova, Elena

    2013-01-01

    This textbook serves as an introduction to fault-tolerance, intended for upper-division undergraduate students, graduate-level students and practicing engineers in need of an overview of the field.  Readers will develop skills in modeling and evaluating fault-tolerant architectures in terms of reliability, availability and safety.  They will gain a thorough understanding of fault tolerant computers, including both the theory of how to design and evaluate them and the practical knowledge of achieving fault-tolerance in electronic, communication and software systems.  Coverage includes fault-tolerance techniques through hardware, software, information and time redundancy.  The content is designed to be highly accessible, including numerous examples and exercises.  Solutions and powerpoint slides are available for instructors.   ·         Provides textbook coverage of the fundamental concepts of fault-tolerance; ·         Describes a variety of basic techniques for achieving fault-toleran...

  20. Fault finder

    Science.gov (United States)

    Bunch, Richard H.

    1986-01-01

    A fault finder for locating faults along a high voltage electrical transmission line. Real time monitoring of background noise and improved filtering of input signals is used to identify the occurrence of a fault. A fault is detected at both a master and remote unit spaced along the line. A master clock synchronizes operation of a similar clock at the remote unit. Both units include modulator and demodulator circuits for transmission of clock signals and data. All data is received at the master unit for processing to determine an accurate fault distance calculation.

  1. Strong paleoearthquakes along the Talas-Fergana Fault, Kyrgyzstan

    Directory of Open Access Journals (Sweden)

    A.M. Korzhenkov

    2014-02-01

    Full Text Available The Talas-Fergana Fault, the largest strike-slip structure in Centred. Asia, forms an obliquely oriented boundary between the northeastern and southwestern parts of the Tianshan mountain belt. The fault underwent active right-lateral strike-slip during the Paleozoic, with right-lateral movements being rejuvenated in the Late Cenozoic. Tectonic movements along the intracontinental strike-slip faults contribute to absorb part of the regional crustal shortening linked to the India-Eurasia collision; knowledge of strike-slip motions along the Talas-Fergana Fault are necessary for a complete assessment of the active deformation of the Tianshan orogen. To improve our understanding of the intracontinental deformation of the Tianshan mountain belt and the occurrence of strong earthquakes along the whole length of the Talas-Fergana Fault, we identify features of relief arising during strong paleoearthquakes along the Talas-Fergana Fault, fault segmentation, the length of seismogenic ruptures, and the energy and age of ancient catastrophes. We show that during neotectonic time the fault developed as a dextral strike-slip fault, with possible dextral displacements spreading to secondary fault planes north of the main fault trace. We determine rates of Holocene and Late Pleistocene dextral movements, and our radiocarbon dating indicates tens of strong earthquakes occurring along the fault zone during arid interval of 15800 years. The reoccurrence of strong earthquakes along the Talas-Fergana Fault zone during the second half of the Holocene is about 300 years. The next strong earthquake along the fault will most probably occur along its southeastern chain during the next several decades. Seismotectonic deformation parameters indicate that M > 7 earthquakes with oscillation intensity I > IX have occurred.

  2. Robust Fault Diagnosis Design for Linear Multiagent Systems with Incipient Faults

    Directory of Open Access Journals (Sweden)

    Jingping Xia

    2015-01-01

    Full Text Available The design of a robust fault estimation observer is studied for linear multiagent systems subject to incipient faults. By considering the fact that incipient faults are in low-frequency domain, the fault estimation of such faults is proposed for discrete-time multiagent systems based on finite-frequency technique. Moreover, using the decomposition design, an equivalent conclusion is given. Simulation results of a numerical example are presented to demonstrate the effectiveness of the proposed techniques.

  3. Numerical experiments to investigate the accuracy of broad-band moment magnitude, Mwp

    Science.gov (United States)

    Hara, Tatsuhiko; Nishimura, Naoki

    2011-12-01

    We perform numerical experiments to investigate the accuracy of broad-band moment magnitude, Mwp. We conduct these experiments by measuring Mwp from synthetic seismograms and comparing the resulting values to the moment magnitudes used in the calculation of synthetic seismograms. In the numerical experiments using point sources, we have found that there is a significant dependence of Mwp on focal mechanisms, and that depths phases have a large impact on Mwp estimates, especially for large shallow earthquakes. Numerical experiments using line sources suggest that the effects of source finiteness and rupture propagation on Mwp estimates are on the order of 0.2 magnitude units for vertical fault planes with pure dip-slip mechanisms and 45° dipping fault planes with pure dip-slip (thrust) mechanisms, but that the dependence is small for strike-slip events on a vertical fault plane. Numerical experiments for huge thrust faulting earthquakes on a fault plane with a shallow dip angle suggest that the Mwp estimates do not saturate in the moment magnitude range between 8 and 9, although they are underestimates. Our results are consistent with previous studies that compared Mwp estimates to moment magnitudes calculated from seismic moment tensors obtained by analyses of observed data.

  4. Central Asia Active Fault Database

    Science.gov (United States)

    Mohadjer, Solmaz; Ehlers, Todd A.; Kakar, Najibullah

    2014-05-01

    The ongoing collision of the Indian subcontinent with Asia controls active tectonics and seismicity in Central Asia. This motion is accommodated by faults that have historically caused devastating earthquakes and continue to pose serious threats to the population at risk. Despite international and regional efforts to assess seismic hazards in Central Asia, little attention has been given to development of a comprehensive database for active faults in the region. To address this issue and to better understand the distribution and level of seismic hazard in Central Asia, we are developing a publically available database for active faults of Central Asia (including but not limited to Afghanistan, Tajikistan, Kyrgyzstan, northern Pakistan and western China) using ArcGIS. The database is designed to allow users to store, map and query important fault parameters such as fault location, displacement history, rate of movement, and other data relevant to seismic hazard studies including fault trench locations, geochronology constraints, and seismic studies. Data sources integrated into the database include previously published maps and scientific investigations as well as strain rate measurements and historic and recent seismicity. In addition, high resolution Quickbird, Spot, and Aster imagery are used for selected features to locate and measure offset of landforms associated with Quaternary faulting. These features are individually digitized and linked to attribute tables that provide a description for each feature. Preliminary observations include inconsistent and sometimes inaccurate information for faults documented in different studies. For example, the Darvaz-Karakul fault which roughly defines the western margin of the Pamir, has been mapped with differences in location of up to 12 kilometers. The sense of motion for this fault ranges from unknown to thrust and strike-slip in three different studies despite documented left-lateral displacements of Holocene and late

  5. 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

  6. 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

  7. [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.

  8. Fluid involvement in normal faulting

    Science.gov (United States)

    Sibson, Richard H.

    2000-04-01

    fluid overpressures are localised within the fault zone and the surrounding rock retains significant tensile strength. Migrating pore fluids interact both statically and dynamically with normal faults. Static effects include consideration of the relative permeability of the faults with respect to the country rock, and juxtaposition effects which determine whether a fault is transmissive to flow or acts as an impermeable barrier. Strong directional permeability is expected in the subhorizontal σ2 direction parallel to intersections between minor faults, extension fractures, and stylolites. Three dynamic mechanisms tied to the seismic stress cycle may contribute to fluid redistribution: (i) cycling of mean stress coupled to shear stress, sometimes leading to postfailure expulsion of fluid from vertical fractures; (ii) suction pump action at dilational fault jogs; and, (iii) fault-valve action when a normal fault transects a seal capping either uniformly overpressured crust or overpressures localised to the immediate vicinity of the fault zone at depth. The combination of σ2 directional permeability with fluid redistribution from mean stress cycling may lead to hydraulic communication along strike, contributing to the protracted earthquake sequences that characterise normal fault systems.

  9. Sawtooth segmentation and deformation processes on the southern San Andreas fault, California

    Science.gov (United States)

    Bilham, R.; Williams, P.

    1985-01-01

    Five contiguous 12-13 km fault segments form a sawtooth geometry on the southernmost San Andreas fault. The kinematic and morphologic properties of each segment depend on fault strike, despite differences of strike between segments of as little as 3 degrees. Oblique slip (transpression) of fault segments within the Indio Hills, Mecca Hills and Durmid Hill results from an inferred 8:1 ratio of dextral slip to convergence across the fault zone. Triggered slip and creep are confined almost entirely to transpressive segments of the fault. Durmid Hill has been formed in the last 28 + or - 6 ka by uplift at an average rate of 3 + or - 1 mm/a.

  10. Major earthquakes occur regularly on an isolated plate boundary fault.

    Science.gov (United States)

    Berryman, Kelvin R; Cochran, Ursula A; Clark, Kate J; Biasi, Glenn P; Langridge, Robert M; Villamor, Pilar

    2012-06-29

    The scarcity of long geological records of major earthquakes, on different types of faults, makes testing hypotheses of regular versus random or clustered earthquake recurrence behavior difficult. We provide a fault-proximal major earthquake record spanning 8000 years on the strike-slip Alpine Fault in New Zealand. Cyclic stratigraphy at Hokuri Creek suggests that the fault ruptured to the surface 24 times, and event ages yield a 0.33 coefficient of variation in recurrence interval. We associate this near-regular earthquake recurrence with a geometrically simple strike-slip fault, with high slip rate, accommodating a high proportion of plate boundary motion that works in isolation from other faults. We propose that it is valid to apply time-dependent earthquake recurrence models for seismic hazard estimation to similar faults worldwide.

  11. Scissoring Fault Rupture Properties along the Median Tectonic Line Fault Zone, Southwest Japan

    Science.gov (United States)

    Ikeda, M.; Nishizaka, N.; Onishi, K.; Sakamoto, J.; Takahashi, K.

    2017-12-01

    The Median Tectonic Line fault zone (hereinafter MTLFZ) is the longest and most active fault zone in Japan. The MTLFZ is a 400-km-long trench parallel right-lateral strike-slip fault accommodating lateral slip components of the Philippine Sea plate oblique subduction beneath the Eurasian plate [Fitch, 1972; Yeats, 1996]. Complex fault geometry evolves along the MTLFZ. The geomorphic and geological characteristics show a remarkable change through the MTLFZ. Extensional step-overs and pull-apart basins and a pop-up structure develop in western and eastern parts of the MTLFZ, respectively. It is like a "scissoring fault properties". We can point out two main factors to form scissoring fault properties along the MTLFZ. One is a regional stress condition, and another is a preexisting fault. The direction of σ1 anticlockwise rotate from N170°E [Famin et al., 2014] in the eastern Shikoku to Kinki areas and N100°E [Research Group for Crustral Stress in Western Japan, 1980] in central Shikoku to N85°E [Onishi et al., 2016] in western Shikoku. According to the rotation of principal stress directions, the western and eastern parts of the MTLFZ are to be a transtension and compression regime, respectively. The MTLFZ formed as a terrain boundary at Cretaceous, and has evolved with a long active history. The fault style has changed variously, such as left-lateral, thrust, normal and right-lateral. Under the structural condition of a preexisting fault being, the rupture does not completely conform to Anderson's theory for a newly formed fault, as the theory would require either purely dip-slip motion on the 45° dipping fault or strike-slip motion on a vertical fault. The fault rupture of the 2013 Barochistan earthquake in Pakistan is a rare example of large strike-slip reactivation on a relatively low angle dipping fault (thrust fault), though many strike-slip faults have vertical plane generally [Avouac et al., 2014]. In this presentation, we, firstly, show deep subsurface

  12. Active transpressional tectonics in the Andean forearc of southern Peru quantified by 10Be surface exposure dating of an active fault scarp

    Science.gov (United States)

    Benavente, Carlos; Zerathe, Swann; Audin, Laurence; Hall, Sarah R.; Robert, Xavier; Delgado, Fabrizio; Carcaillet, Julien; Team, Aster

    2017-09-01

    Our understanding of the style and rate of Quaternary tectonic deformation in the forearc of the Central Andes is hampered by a lack of field observations and constraints on neotectonic structures. Here we present a detailed analysis of the Purgatorio fault, a recently recognized active fault located in the forearc of southern Peru. Based on field and remote sensing analysis (Pléiades DEM), we define the Purgatorio fault as a subvertical structure trending NW-SE to W-E along its 60 km length, connecting, on its eastern end, to the crustal Incapuquio Fault System. The Purgatorio fault accommodates right-lateral transpressional deformation, as shown by the numerous lateral and vertical plurimetric offsets recorded along strike. In particular, scarp with a 5 m cumulative throw is preserved and displays cobbles that are cut and covered by slickensides. Cosmogenic radionuclide exposure dating (10Be) of quartzite cobbles along the vertical fault scarp yields young exposure ages that can be bracketed between 0 to 6 ka, depending on the inheritance model that is applied. Our preferred scenario, which takes in account our geomorphic observations, implies at least two distinct rupture events, each associated with 3 and 2 m of vertical offset. These two events plausibly occurred during the last thousand years. Nevertheless, an interpretation invoking more tectonic events along the fault cannot be ruled out. This work affirms crustal deformation along active faults in the Andean forearc of southern Peru during the last thousand years.

  13. Slip partitioning on the Enriquillo and Lamentin faults during the 2010 Haiti earthquake

    Science.gov (United States)

    Saint Fleur, Newdeskarl; Feuillet, Nathalie; Grandin, Raphaël; Jacques, Éric; Weil-Accardo, Jennifer; Klinger, Yann

    2014-05-01

    A general consensus has emerged from the study of the 12 January 2010, Mw 7.0 Haiti earthquake: the coseismic rupture was complex, portraying both reverse and strike-slip motion, but lacking unambiguous surface break. Based on seismological, geodetic and geologic data, numerous slip models have been proposed for that event. However, using an incomplete fault map, the latter models were preliminary, proposing a rupture on unmapped buried faults. Here, using bathymetric data offshore Port-au-Prince along with a digital elevation model derived from LiDAR on-land, we identified the south-dipping Lamentin thrust in the Bay of Port-au-Prince. The fault prolongs on-land where it deforms active alluvial fans in the city of Carrefour. The geometry and distribution of the aftershocks of the 2010 earthquake and the analysis of the regional geology allow us to place constraints on the connection at depth between the Lamentin thrust and the sinistral strike-slip Enriquillo -Plantain Garden Fault (EPGF). Inversion of geodetic data suggests that both faults may have broken in 2010, consistently with the regional geodynamical setting. The rupture initiated along the Lamentin thrust and further propagated along the EPGF due to instantaneous unclamping at depth. The corals uplifted around the Léogâne Delta Fan, contributing to the build-up of long-term topography between the Lamentin thrust and the EPGF. The 2010 earthquake increased the stress toward failure on unruptured EPGF segments as well as on the thrust fault sitting in the middle of the city of Carrefour, in the direct vicinity of Port-au-Prince, thereby increasing the seismic hazard in these areas.

  14. Complex fragmentation and silicification structures in fault zones: quartz mineralization and repeated fragmentation along the Fountain Range Fault (Mt. Isa Inlier, Australia)

    Science.gov (United States)

    Seybold, Lina; Blenkinsop, Tom; Heuss, Soraya; Ord, Alison; Kruhl, Jörn H.

    2015-04-01

    In large-scale fault zones fracture networks are commonly generated by high volumes of pressurized fluids, followed by quartz precipitation. In this way large amounts of quartz are formed as microcrystalline masses and as complex vein systems, with partly highly different textures, as a result of different formation processes. Based on field and microstructural data and the quantification of vein patterns, the spatial and temporal connection between fragmentation, quartz crystallization and fluid and material flow along the Fountain Range Fault at Fountain Springs was investigated. Dextral strike-slip led to up to 25 km horizontal displacement along the fault. Due to various fragmentation and quartz formation processes, a ca. 100 m high, 80 - 100 m wide and km-long quartz ridge with numerous vein systems and variable microfabrics was formed. Locally, lenses of highly altered metamorphic wall-rocks occur in the quartz zone. Where exposed, the contact to wall rocks is sharp. Millimetre- to decimetre-thick quartz veins penetrate the wall-rocks only within metre distance from the contact. Several clearly distinguishable fine-grained reddish, brownish to dark and pigment-rich quartz masses form up to 50 m wide and up to several 100 m long steep lenses that build the major part of the silicified fault zone. A chronology can be established. Some of these lenses are oriented slightly oblique to the general trend of the quartz zone, in agreement with the supposed dextral strike slip along the fault. Numerous generations of typically µm-cm thick quartz veins transect the microcrystalline quartz masses and, locally, form anisotropic networks. In the quartz masses, angular fragments often composed of quartz with, again, internal fragmentation structures, indicate earlier fracturing and silicification events. Within the veins, quartz forms geodes, locally filled with fine-grained reddish quartz and palisade structures with feathery textures and fluid-inclusion zoning

  15. Numerical Modeling of CO2 and Brine Leakage through Open Fracture in a Fault Zone: Open Channel Flow or Darcy Flow

    Directory of Open Access Journals (Sweden)

    Ning Liu

    2017-01-01

    Full Text Available Understanding fluids migration and leakage risk along the fault zone is necessary to guarantee the safety of CO2 geological storage. The validity of Darcy’s law gets challenged in dealing with the flow in open fractures since the occurring of turbulence flow. In this study, we develop a 2D model with usage of T2Well, an integrated wellbore-reservoir simulator, to investigate the leakage problem along open fractures which are embedded in a fault zone from the deep injection reservoir to shallow aquifers. The results record a positive feedback of gas expansion and pressure response in fracture, which causes a quick downward propagation of highly gas saturated zone from the top of fracture and an easy gas breakthrough in the shallower aquifers. The decreasing of aperture size of fracture significantly enhances the leakage rates in fracture, but with less influences as aperture increases. In comparison, the Equivalent Porous Media models show a good approximation with the momentum model of large apertures but poor for the small one. Nevertheless, the differences are small in terms of final CO2 distribution among various aquifers, suggesting that Darcy’s law may be still “effective” in solving flow problem along fractures in a constant injection system at a large time scale.

  16. Fault detection by Turam TEM survey. Numerical model studies and a case history; TEM ho Turam sokutei haichi ni yoru danso kenshutsu no kokoromi. Model keisan to jisshirei

    Energy Technology Data Exchange (ETDEWEB)

    Wada, K.; Tsutsui, T. [Mitsui Mineral Development Engineering Co. Ltd., Tokyo (Japan); Ito, T. [Chiba Univ., Chiba (Japan). Faculty of Science; Takeuchi, A. [Toyama University, Toyama (Japan). Faculty of Science; He, P. [Power Reactor and Nuclear fuel Development Corp., Tokyo (Japan)

    1997-05-27

    With an objective to detect faults estimated to exist along the Shigesumi valley in the Kamioka mine, discussions were given by using electromagnetic survey, which uses the Turam measurement arrangement based on the TEM method, and three-dimensional model calculations. The Turam measurement arrangement, which installs transmission loop fixedly, is used to identify nature and distribution of electrically conductive objects upon noticing abnormal portions in magnetic fields in the measurement data. In the model calculation, the plate model calculation method and the FDTD method were used, and so was the calculation code TEM3DL. The result revealed that strong topographical influence is seen from steep V-shaped valley existing along the traverse line in the measurement data, but an abnormal resistivity band accompanying remarkable distortion in the curve was detected. According to the result of the model calculation, anomaly detection may be found difficult in locations where a low resistivity band has not grown enough locally. It was possible from these facts to assume a model in which the low resistivity band exists directly below the Shigesumi valley, suggesting existence of faults. 2 refs., 8 figs.

  17. Comparison of fault-related folding algorithms to restore a fold-and-thrust-belt

    Science.gov (United States)

    Brandes, Christian; Tanner, David

    2017-04-01

    Fault-related folding means the contemporaneous evolution of folds as a consequence of fault movement. It is a common deformation process in the upper crust that occurs worldwide in accretionary wedges, fold-and-thrust belts, and intra-plate settings, in either strike-slip, compressional, or extensional regimes. Over the last 30 years different algorithms have been developed to simulate the kinematic evolution of fault-related folds. All these models of fault-related folding include similar simplifications and limitations and use the same kinematic behaviour throughout the model (Brandes & Tanner, 2014). We used a natural example of fault-related folding from the Limón fold-and-thrust belt in eastern Costa Rica to test two different algorithms and to compare the resulting geometries. A thrust fault and its hanging-wall anticline were restored using both the trishear method (Allmendinger, 1998; Zehnder & Allmendinger, 2000) and the fault-parallel flow approach (Ziesch et al. 2014); both methods are widely used in academia and industry. The resulting hanging-wall folds above the thrust fault are restored in substantially different fashions. This is largely a function of the propagation-to-slip ratio of the thrust, which controls the geometry of the related anticline. Understanding the controlling factors for anticline evolution is important for the evaluation of potential hydrocarbon reservoirs and the characterization of fault processes. References: Allmendinger, R.W., 1998. Inverse and forward numerical modeling of trishear fault propagation folds. Tectonics, 17, 640-656. Brandes, C., Tanner, D.C. 2014. Fault-related folding: a review of kinematic models and their application. Earth Science Reviews, 138, 352-370. Zehnder, A.T., Allmendinger, R.W., 2000. Velocity field for the trishear model. Journal of Structural Geology, 22, 1009-1014. Ziesch, J., Tanner, D.C., Krawczyk, C.M. 2014. Strain associated with the fault-parallel flow algorithm during kinematic fault

  18. Integrated seismic interpretation of the Carlsberg Fault zone, Copenhagen, Denmark

    DEFF Research Database (Denmark)

    Nielsen, Lars; Thybo, Hans; Jørgensen, Mette Iwanouw

    2005-01-01

    the fault zone. The fault zone is a shadow zone to shots detonated outside the fault zone. Finite-difference wavefield modelling supports the interpretations of the fan recordings. Our fan recording approach facilitates cost-efficient mapping of fault zones in densely urbanized areas where seismic normal......We locate the concealed Carlsberg Fault zone along a 12-km-long trace in the Copenhagen city centre by seismic refraction, reflection and fan profiling. The Carlsberg Fault is located in a NNW-SSE striking fault system in the border zone between the Danish Basin and the Baltic Shield. Recent...... earthquakes indicate that this area is tectonically active. A seismic refraction study across the Carlsberg Fault shows that the fault zone is a low-velocity zone and marks a change in seismic velocity structure. A normal incidence reflection seismic section shows a coincident flower-like structure. We have...

  19. Fault Orientations at Obliquely Rifted Margins: Where? When? Why?

    Science.gov (United States)

    Brune, Sascha

    2015-04-01

    Present-day knowledge of rifted margin formation is largely based on 2D seismic lines, 2D conceptual models, and corroborated by 2D numerical experiments. However, the 2D assumption that the extension direction is perpendicular to the rift trend is often invalid. In fact, worldwide more than 75% of all rifted margin segments have been formed under significant obliquity exceeding 20° (angle measured between extension direction and rift trend normal): During formation of the Atlantic Ocean, oblique rifting dominated at the sheared margins of South Africa and Patagonia, the Equatorial Atlantic margins, separation of Greenland and North America, and it played a major role in the protracted rift history of the North East Atlantic. Outside the Atlantic Ocean, oblique rifting occurred during the split between East and West Gondwana, the separation of India and Australia, India and Madagascar, Australia and Antarctica, as well as Arabia and Africa. It is presently observed in the Gulf of California, the Aegean and in the East African Rift. Despite its significance, the degree to which oblique lithospheric extension affects first-order rift and passive margin properties like surface stress pattern, fault azimuths, and basin geometry, is still not entirely clear. This contribution provides insight in crustal stress patterns and fault orientations by applying a 3D numerical rift model to oblique extensional settings. The presented forward experiments cover the whole spectrum of oblique extension (i.e. rift-orthogonal extension, low obliquity, high obliquity, strike-slip deformation) from initial deformation to breakup. They are conducted using an elasto-visco-plastic finite element model and involve crustal and mantle layers accounting for self-consistent necking of the lithosphere. Results are thoroughly compared to previous analogue experiments, which yields many similarities but also distinct differences for late rift stages and for high obliquity. Even though the model

  20. Imaging of Subsurface Faults using Refraction Migration with Fault Flooding

    KAUST Repository

    Metwally, Ahmed Mohsen Hassan

    2017-05-31

    We propose a novel method for imaging shallow faults by migration of transmitted refraction arrivals. The assumption is that there is a significant velocity contrast across the fault boundary that is underlain by a refracting interface. This procedure, denoted as refraction migration with fault flooding, largely overcomes the difficulty in imaging shallow faults with seismic surveys. Numerical results successfully validate this method on three synthetic examples and two field-data sets. The first field-data set is next to the Gulf of Aqaba and the second example is from a seismic profile recorded in Arizona. The faults detected by refraction migration in the Gulf of Aqaba data were in agreement with those indicated in a P-velocity tomogram. However, a new fault is detected at the end of the migration image that is not clearly seen in the traveltime tomogram. This result is similar to that for the Arizona data where the refraction image showed faults consistent with those seen in the P-velocity tomogram, except it also detected an antithetic fault at the end of the line. This fault cannot be clearly seen in the traveltime tomogram due to the limited ray coverage.

  1. Influence of fault heterogeneity on the frequency-magnitude statistics of earthquake cycle simulations

    Science.gov (United States)

    Norbeck, Jack; Horne, Roland

    2017-04-01

    Numerical models are useful tools for investigating natural geologic conditions can affect seismicity, but it can often be difficult to generate realistic earthquake sequences using physics-based earthquake rupture models. Rate-and-state earthquake cycle simulations on planar faults with homogeneous frictional properties and stress conditions typically yield single event sequences with a single earthquake magnitude characteristic of the size of the fault. In reality, earthquake sequences have been observed to follow a Gutenberg-Richter-type frequency-magnitude distribution that can be characterized by a power law scaling relationship. The purpose of this study was to determine how fault heterogeneity can affect the frequency-magnitude distribution of simulated earthquake events. We considered the effects fault heterogeneity at two different length-scales by performing numerical earthquake rupture simulations within a rate-and-state friction framework. In our first study, we investigated how heterogeneous, fractal distributions of shear and normal stress resolved along a two-dimensional fault surface influenced the earthquake nucleation, rupture, and arrest processes. We generated a catalog of earthquake events by performing earthquake cycle simulations for 90 random realizations of fractal stress distributions. Typical realizations produced between 4 to 6 individual earthquakes ranging in event magnitudes between those characteristic of the minimum patch size for nucleation and the size of the model fault. The resulting aggregate frequency-magnitude distributions were characterized well by a power-law scaling behavior. In our second study, we performed simulations of injection-induced seismicity using a coupled fluid flow and rate-and-state earthquake model. Fluid flow in a two-dimensional reservoir was modeled, and the fault mechanics was modeled under a plane strain assumption (i.e., one-dimensional faults). We generated a set of faults with an average strike of

  2. Methods for recognition and segmentation of active fault

    International Nuclear Information System (INIS)

    Hyun, Chang Hun; Noh, Myung Hyun; Lee, Kieh Hwa; Chang, Tae Woo; Kyung, Jai Bok; Kim, Ki Young

    2000-03-01

    In order to identify and segment the active faults, the literatures of structural geology, paleoseismology, and geophysical explorations were investigated. The existing structural geological criteria for segmenting active faults were examined. These are mostly based on normal fault systems, thus, the additional criteria are demanded for application to different types of fault systems. Definition of the seismogenic fault, characteristics of fault activity, criteria and study results of fault segmentation, relationship between segmented fault length and maximum displacement, and estimation of seismic risk of segmented faults were examined in paleoseismic study. The history of earthquake such as dynamic pattern of faults, return period, and magnitude of the maximum earthquake originated by fault activity can be revealed by the study. It is confirmed through various case studies that numerous geophysical explorations including electrical resistivity, land seismic, marine seismic, ground-penetrating radar, magnetic, and gravity surveys have been efficiently applied to the recognition and segmentation of active faults

  3. Respecting the right to strike

    CERN Multimedia

    Staff Association

    2015-01-01

    Since two years the representatives of the employers in the ILO, a tripartite multilateral body responsible for guaranteeing the correct application of an international labour code, try to weaken the global work regulations. On the occasion of the Global Day of Action for the right to strike at the invitation of the Geneva community of Union action (Communauté genevoise d’action syndicale) and the Swiss Trade Union Association (Union syndicale suisse) around noon on Wednesday 18th February some fifty staff representatives of international organizations gathered on the place des Nations in Geneva to reaffirm the importance of this fundamental right, too often flouted. A delegation of the CERN Staff Association was also present. In a short speech, the Staff Association said that, while being one of the fundamental human rights, to be efficient the right to strike must be used intelligently. It must be implemented taking into account the sensitivities of the professional environment and r...

  4. Stress evolution and fault stability during the Weichselian glacial cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lund, Bjoern; Schmidt, Peter; Hieronymus, Christoph (Dept. of Earth Sciences, Uppsala Univ., Uppsala (Sweden))

    2009-10-15

    In this report we examine how the waxing and waning of an ice sheet during a glacial cycle affects the state of stress in the Earth, and how those changes in stress influence the stability of faults. We focus on the stresses at repository depth in Forsmark and Oskarshamn, and on the stability field at seismogenic depth at the proposed repository sites and at the Paervie endglacial fault in northern Sweden. This study is a modelling study, where we use 3-dimensional ice and earth models to calculate the glacial isostatic adjustment (GIA), i.e. the response of the Earth to an ice load, examining both displacements and stresses. We use a flat-earth finite element approach, based on Wu with some modifications. The result presented here is a continuation of previous studies in 2 dimensions and complement those studies in assessing how the 3-dimensionality of the problem affects the conclusions. We use the Fennoscandian ice model of Naeslund, which is a dynamic ice sheet model based on climate reconstructions with constraints from geological observations. The ice model spans the entire Weichselian glaciation but we only use the last 68 kyr, which includes the 2 major periods of ice cover as depicted in this ice sheet reconstruction. For the GIA calculation we use a number of different earth models, both with flat horizontal layers and with various 3D structures of lithosphere thickness. We don't include lateral variations in the viscosity of the mantle. Comparing the current day rebound velocities predicted by our models with GPS observations from the BIFROST project, we note that in general, we can obtain a reasonable fit to the observations with our models, and that the results are rather sensitive to the assumed viscosity of the mantle. We find that the differences between data and model results, for all earth models, have common features which we interpret as due to the ice model. These observations are in agreement with numerous other GIA studies. Our flat

  5. Stress evolution and fault stability during the Weichselian glacial cycle

    International Nuclear Information System (INIS)

    Lund, Bjoern; Schmidt, Peter; Hieronymus, Christoph

    2009-01-01

    In this report we examine how the waxing and waning of an ice sheet during a glacial cycle affects the state of stress in the Earth, and how those changes in stress influence the stability of faults. We focus on the stresses at repository depth in Forsmark and Oskarshamn, and on the stability field at seismogenic depth at the proposed repository sites and at the Paervie endglacial fault in northern Sweden. This study is a modelling study, where we use three-dimensional ice and earth models to calculate the glacial isostatic adjustment (GIA), i.e. the response of the Earth to an ice load, examining both displacements and stresses. We use a flat-earth finite element approach, based on Wu with some modifications. The result presented here is a continuation of previous studies in two dimensions and complement those studies in assessing how the three-dimensionality of the problem affects the conclusions. We use the Fennoscandian ice model of Naeslund, which is a dynamic ice sheet model based on climate reconstructions with constraints from geological observations. The ice model spans the entire Weichselian glaciation but we only use the last 68 kyr, which includes the two major periods of ice cover as depicted in this ice sheet reconstruction. For the GIA calculation we use a number of different earth models, both with flat horizontal layers and with various 3D structures of lithosphere thickness. We do not include lateral variations in the viscosity of the mantle. Comparing the current day rebound velocities predicted by our models with GPS observations from the BIFROST project, we note that in general, we can obtain a reasonable fit to the observations with our models, and that the results are rather sensitive to the assumed viscosity of the mantle. We also find that the differences between data and model results, for all earth models, have common features which we interpret as due to the ice model. These observations are in agreement with numerous other GIA studies

  6. Fault diagnosis

    Science.gov (United States)

    Abbott, Kathy

    1990-01-01

    The objective of the research in this area of fault management is to develop and implement a decision aiding concept for diagnosing faults, especially faults which are difficult for pilots to identify, and to develop methods for presenting the diagnosis information to the flight crew in a timely and comprehensible manner. The requirements for the diagnosis concept were identified by interviewing pilots, analyzing actual incident and accident cases, and examining psychology literature on how humans perform diagnosis. The diagnosis decision aiding concept developed based on those requirements takes abnormal sensor readings as input, as identified by a fault monitor. Based on these abnormal sensor readings, the diagnosis concept identifies the cause or source of the fault and all components affected by the fault. This concept was implemented for diagnosis of aircraft propulsion and hydraulic subsystems in a computer program called Draphys (Diagnostic Reasoning About Physical Systems). Draphys is unique in two important ways. First, it uses models of both functional and physical relationships in the subsystems. Using both models enables the diagnostic reasoning to identify the fault propagation as the faulted system continues to operate, and to diagnose physical damage. Draphys also reasons about behavior of the faulted system over time, to eliminate possibilities as more information becomes available, and to update the system status as more components are affected by the fault. The crew interface research is examining display issues associated with presenting diagnosis information to the flight crew. One study examined issues for presenting system status information. One lesson learned from that study was that pilots found fault situations to be more complex if they involved multiple subsystems. Another was pilots could identify the faulted systems more quickly if the system status was presented in pictorial or text format. Another study is currently under way to

  7. Spatial and temporal variability in faulting along a Quaternary fault transect across the Northern Walker Lane, California-Nevada

    Science.gov (United States)

    Gold, R. D.; Briggs, R. W.; Crone, A. J.

    2013-12-01

    What are the temporal and spatial patterns of faulting across shear zones with overlapping parallel faults that are preferentially oriented to accommodate regional shear? How should earthquake hazard be modeled if these systems have variable earthquake recurrence? We explore these questions in the Northern Walker Lane, a 100-km-wide zone of dextral shear along the eastern side of the Sierra Nevada, which accommodates ~15% of the 50 mm/yr of relative motion between the Pacific and North American plates. We used high-resolution airborne Light Distance and Ranging (LiDAR) data to create surficial geologic maps, conducted paleoseismic trenching, applied Quaternary geochronology, and collected high-resolution seismic-reflection profiles along a fault-perpendicular transect across the principal, subparallel, northwest-striking Mohawk Valley, Grizzly Valley, Honey Lake, and Warm Springs Valley dextral-slip faults. Key results along this transect from southwest-to-northeast are: (1) trenching at the Sulphur Creek Sidehill Bench site on the Mohawk Valley fault system indicates four surface-rupturing earthquakes since ~14 ka, which is fewer events than inferred from the slip rate of 2.9 mm/yr from geodetic block-models. To reconcile these results, we suggest that strain is widely distributed on numerous uncharacterized fault strands or that the contemporary (geodetic block model) rate is a young phenomena and hasn't been sustained since 14 ka. (2) High-resolution shallow seismic-reflection imaging and topographic analysis using the LiDAR data provide the first conclusive evidence that the Grizzly Valley fault system is an active Quaternary structure, with probable motion in the latest Quaternary. This result is significant because this fault system is not presently included in the USGS Quaternary fault-and-fold database, is not specified as a seismic source in most regional hazard models, and is also not defined as a boundary in regional geodetic block models. (3) New

  8. Are "uncharacteristic" earthquakes spatially linked to strike-slip restraining bends?

    Science.gov (United States)

    Mann, P.

    2011-12-01

    On the basis of a compilation of paleoseismological data from the Wasatch and San Andreas faults, Schwartz and Coppersmith (1984) proposed that both plate boundary and intraplate faults tend to generate essentially same size earthquakes having a relatively narrow range of magnitudes near the maximum. They referred to these earthquakes as "characteristic earthquakes". Their hypothesis suggests that the historical record of earthquakes documented for periods of time ranging from centuries to millennia in different parts of the world that could allow predictions of future ruptures. The characteristic earthquake model works surprisingly well for major strike-slip faults like the North Anatolian fault of Turkey and the North Tabriz strike-slip fault in Iran which both show a progressive, uni-direction pattern of rupture starting at one point and "unzippering" over a distance of hundreds of kilometers in a series of earthquakes. This regular periodicity has been attributed to systematic changes in Coulomb failure stress on individual faults or interconnected fault networks defined by distinctive changes in fault strike, or stepover faults, or by the intersection of a neighboring fault. However, studies of the San Andreas, Wasatch, and Dead Sea faults show that earthquake ruptures are not periodic and instead form clusters of events with no obvious "recurrence interval" as predicted by the characteristic earthquake model. Some of these hard-to-forecast "uncharacteristic" earthquakes initiate as blind thrust faults formed at deeper levels in the crust near the brittle-plastic transition zone as illustrated by the 1989 M 6.9 Loma Prieta earthquake of California. Such events would produce little or no surface rupture of the main fault plane so the effects of this type of earthquake would remain impossible for future paleoseismologists to discern (other than from shaking effects and the broad vertical uplift related to vertical motions on deeply buried faults). More recently

  9. The mechanics of a magma chamber-fault system in trans-tension with application to Coso

    Science.gov (United States)

    Simakin, Alexander G.; Ghassemi, Ahmad

    2007-12-01

    The mechanical interaction between an elliptically shaped magma chamber and a fault subject to transtension is investigated with particular reference to the Coso geothermal field. The geologic setting of the Coso field is interpreted as a releasing bend step-over structure formed by the Airport Lake and Owens Valley dextral strike-slip fault system. The role of the Coso volcano-magmatic center in the development of the "over-step" structure is examined by treating the magma chamber as a liquid inclusion in a viscoelastic crust containing a fault (Airport Lake). The problem is numerically solved using a 2D viscoelastic finite element model with thermally activated viscosity to account for thermal weakening of the rock. The temperature distribution around the magma body is calculated based on a 3D steady-state approach and using the mesh-less numerical method. The fault is modeled as a frictionless contact. The simulated distributions of stress and strain around the inclusion display a rotation caused by the shearing component of the applied transtension. The results indicate that the fault tends to overstep the chamber in a geometric pattern similar to a step-over. There is good correspondence between the computed distributions of the maximum shear stress in the vicinity of the magma chamber and the map of earthquake epicenters at a depth of 7-10 km in Coso.

  10. Slip distribution of the 2015 Lefkada earthquake and its implications for fault segmentation

    Science.gov (United States)

    Bie, Lidong; González, Pablo J.; Rietbrock, Andreas

    2017-07-01

    It is widely accepted that fault segmentation limits earthquake rupture propagations and therefore earthquake size. While along-strike segmentation of continental strike-slip faults is well observed, direct evidence for segmentation of off-shore strike-slip faults is rare. A comparison of rupture behaviours in multiple earthquakes might help reveal the characteristics of fault segmentation. In this work, we study the 2015 Lefkada earthquake, which ruptured a major active strike slip fault offshore Lefkada Island, Greece. We report ground deformation mainly on the Lefkada Island measured by interferometric synthetic radar (InSAR), and infer a coseismic distributed slip model. To investigate how the fault location affects the inferred displacement based on our InSAR observations, we conduct a suite of inversions by taking various fault location from different studies as a prior. The result of these test inversions suggests that the Lefkada fault trace is located just offshore Lefkada Island. Our preferred model shows that the 2015 earthquake main slip patches are confined to shallow depth (Lefkada fault, we suggest that the 2015 earthquake closed the seismic gap, at least partially, left by the 2003 earthquake by rupturing the shallow part of the Lefkada fault. The spatial variation in slip distributions for the two earthquakes reveals segmentation along strike, and possibly downdip of the Lefkada fault. A comparison of aftershock locations and coseismic slip distribution shows that most aftershocks appear near the edge of main coseismic slip patches.

  11. Fault Recoverability Analysis via Cross-Gramian

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza

    2016-01-01

    Engineering systems are vulnerable to different kinds of faults. Faults may compromise safety, cause sub-optimal operation and decline in performance if not preventing the whole system from functioning. Fault tolerant control (FTC) methods ensure that the system performance maintains within...... an acceptable level at the occurrence of the faults. These techniques cannot be successful if the necessary redundancy does not exist in the system. Fault recoverability which is also known as control reconfigurability is a mathematical measure which quantifies the level of redundancy in connection...... with feedback control. Fault recoverability provides important and useful information which could be used in analysis and design. However, computing fault recoverability is numerically expensive. In this paper, a new approach for computation of fault recoverability for bilinear systems is proposed...

  12. Testing the influence of vertical, pre-existing joints on normal faulting using analogue and 3D discrete element models (DEM)

    Science.gov (United States)

    Kettermann, Michael; von Hagke, Christoph; Virgo, Simon; Urai, Janos L.

    2015-04-01

    Brittle rocks are often affected by different generations of fractures that influence each other. We study pre-existing vertical joints followed by a faulting event. Understanding the effect of these interactions on fracture/fault geometries as well as the development of dilatancy and the formation of cavities as potential fluid pathways is crucial for reservoir quality prediction and production. Our approach combines scaled analogue and numerical modeling. Using cohesive hemihydrate powder allows us to create open fractures prior to faulting. The physical models are reproduced using the ESyS-Particle discrete element Modeling Software (DEM), and different parameters are investigated. Analogue models were carried out in a manually driven deformation box (30x28x20 cm) with a 60° dipping pre-defined basement fault and 4.5 cm of displacement. To produce open joints prior to faulting, sheets of paper were mounted in the box to a depth of 5 cm at a spacing of 2.5 cm. Powder was then sieved into the box, embedding the paper almost entirely (column height of 19 cm), and the paper was removed. We tested the influence of different angles between the strike of the basement fault and the joint set (0°, 4°, 8°, 12°, 16°, 20°, and 25°). During deformation we captured structural information by time-lapse photography that allows particle imaging velocimetry analyses (PIV) to detect localized deformation at every increment of displacement. Post-mortem photogrammetry preserves the final 3-dimensional structure of the fault zone. We observe that no faults or fractures occur parallel to basement-fault strike. Secondary fractures are mostly oriented normal to primary joints. At the final stage of the experiments we analyzed semi-quantitatively the number of connected joints, number of secondary fractures, degree of segmentation (i.e. number of joints accommodating strain), damage zone width, and the map-view area fraction of open gaps. Whereas the area fraction does not change

  13. Weixi-Qiaohou Fault in Southwest China: Recent Active Features and Relationship with Red River Fault

    Science.gov (United States)

    Zufeng, C.; JianLin, L.

    2017-12-01

    The Sichuan-Yunnan block in the eastern margin of the Tibetan plateau is a very active block characterized by lateral extrusion and frequent seismicity. Based on geologic and geomorphic field observations, we present late-Quaternary active features of the Weixi-Qiaohou Fault located in the western margin of the Sichuan-Yunnan block, and discuss the relationship between the Weixi-Qiaohou Fault and the Red River Fault in southwest China. The Weixi-Qiaohou Fault has apparently dominated the development of many late Cenozoic basins, showing dextral strike-slip motion features as expressed by synchronous right-lateral dislocation of mountain ridges and rivers. The Weixi-Qiaohou Fault has displaced late Pleistocene to Holocene accumulations revealed by exploratory trenches at Yushichang, Desheng, and Changyi. There is a fault scarp of 3km long and 2.5m high on the river terraces and the alluvial fans near Yanqu and Shiyan. The fault is estimated to have an average movement rate of 1.8-2.4mm/ /yr. horizontally and 0.3 0.35mm/yr. vertically since late Pleistocene, based on displacement magnitude of the alluvial fans, gullies and river terraces. The Weixi-Qiaohou Fault appears to have significant links with the Red River Fault in the south and the Jinsha River Fault in the north. Since late Cenozoic, the Weixi-Qiaohou Fault has developed kinematics similar to the Red River Fault and the Jinsha River Fault, indicating that the Weixi-Qiaohou Fault could be the northern segment of the Red River Fault, and that the Weixi-Qiaohou, Red River and Jinsha River faults constitute the western boundary of the Sichuan-Yunnan active block.

  14. Identification of Lembang fault, West-Java Indonesia by using controlled source audio-magnetotelluric (CSAMT)

    Science.gov (United States)

    Sanny, Teuku A.

    2017-07-01

    The objective of this study is to determine boundary and how to know surrounding area between Lembang Fault and Cimandiri fault. For the detailed study we used three methodologies: (1). Surface deformation modeling by using Boundary Element method and (2) Controlled Source Audiomagneto Telluric (CSAMT). Based on the study by using surface deformation by using Boundary Element Methods (BEM), the direction Lembang fault has a dominant displacement in east direction. The eastward displacement at the nothern fault block is smaller than the eastward displacement at the southern fault block which indicates that each fault block move in left direction relative to each other. From this study we know that Lembang fault in this area has left lateral strike slip component. The western part of the Lembang fault move in west direction different from the eastern part that moves in east direction. Stress distribution map of Lembang fault shows difference between the eastern and western segments of Lembang fault. Displacement distribution map along x-direction and y-direction of Lembang fault shows a linement oriented in northeast-southwest direction right on Tangkuban Perahu Mountain. Displacement pattern of Cimandiri fault indicates that the Cimandiri fault is devided into two segment. Eastern segment has left lateral strike slip component while the western segment has right lateral strike slip component. Based on the displacement distribution map along y-direction, a linement oriented in northwest-southeast direction is observed at the western segment of the Cimandiri fault. The displacement along x-direction and y-direction between the Lembang and Cimandiri fault is nearly equal to zero indicating that the Lembang fault and Cimandiri Fault are not connected to each others. Based on refraction seismic tomography that we know the characteristic of Cimandiri fault as normal fault. Based on CSAMT method th e lembang fault is normal fault that different of dip which formed as

  15. 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

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

    Indian Academy of Sciences (India)

    In nature, these set ups roughly simulate a major strike slip basement fault system with a package of sedimentary rocks deforming by basement-induced wrenching and/or transpression. Models were made up of clay mixed with water in the ratio 3:1. Approximate undrained shear strength of the clay paste was around 2 KPa ...

  17. Macular damage following lightning strikes.

    Science.gov (United States)

    Augustin, A J; Koch, F; Böker, T

    1995-07-01

    Two men with recent history of lightining strike were referred to our hospital. Both patients complained of metamorphosia in one eye and reduced visual acuity. Funduscopy revealed target-like alterations at the fovea. Fluorescein angiography showed window defects of the central retinal pigment epithelium in both patients. One patient developed an anterior subcapsular cataract. If the eye is part of the current-circuit, the melanin granules of the iris, pigment epithelium, and choroid might act as a resistor. The resulting accumulation of heat may lead to damage of the surrounding tissues.

  18. Tectonic and gravity-induced deformation along the active Talas-Fergana Fault, Tien Shan, Kyrgyzstan

    Science.gov (United States)

    Tibaldi, A.; Corazzato, C.; Rust, D.; Bonali, F. L.; Pasquarè Mariotto, F. A.; Korzhenkov, A. M.; Oppizzi, P.; Bonzanigo, L.

    2015-08-01

    This paper shows, by field palaeoseismological data, the Holocene activity of the central segment of the intracontinental Talas-Fergana Fault (TFF), and the relevance of possible future seismic shaking on slope stability around a large water reservoir. The fault, striking NW-SE, is marked by a continuous series of scarps, deflected streams and water divides, and prehistoric earthquakes that offset substrate and Holocene deposits. Fault movements are characterised by right-lateral strike-slip kinematics with a subordinate component of uplift of the NE block. Structural, geological and geomorphological field data indicate that shallow and deep landslides are aligned along the TFF, and some of them are active. Where the TFF runs close to the reservoir, the fault trace is obscured by a series of landslides, affecting rock and soil materials and ranging in size from small slope instabilities to deep-seated gravity-induced slope deformations (DGSDs). The largest of these, which does not show clear evidence of present-day activity, involves a volume of about 1 km3 and is associated with smaller but active landslides in its lower part, with volumes in the order of 2.5 × 104 m3 to 1 × 106 m3. Based on the spatial and temporal relations between landslides and faults, we argue that at least some of these slope failures may have a coseismic character. Stability analyses by means of limit equilibrium methods (LEMs), and stress-strain analysis by finite difference numerical modelling (FDM), were carried out to evaluate different hazard scenarios linked to these slope instabilities. The results indicate concern for the different threats posed, ranging from the possible disruption of the M-41 highway, the main transportation route in central Asia, to the possible collapse of huge rock masses into the reservoir, possibly generating a tsunami.

  19. Fethiye-Burdur Fault Zone (SW Turkey): a myth?

    Science.gov (United States)

    Kaymakci, Nuretdin; Langereis, Cornelis; Özkaptan, Murat; Özacar, Arda A.; Gülyüz, Erhan; Uzel, Bora; Sözbilir, Hasan

    2017-04-01

    Fethiye Burdur Fault Zone (FBFZ) is first proposed by Dumont et al. (1979) as a sinistral strike-slip fault zone as the NE continuation of Pliny-Strabo trench in to the Anatolian Block. The fault zone supposed to accommodate at least 100 km sinistral displacement between the Menderes Massif and the Beydaǧları platform during the exhumation of the Menderes Massif, mainly during the late Miocene. Based on GPS velocities Barka and Reilinger (1997) proposed that the fault zone is still active and accommodates sinistral displacement. In order to test the presence and to unravel its kinematics we have conducted a rigorous paleomagnetic study containing more than 3000 paleomagnetic samples collected from 88 locations and 11700 fault slip data collected from 198 locations distributed evenly all over SW Anatolia spanning from Middle Miocene to Late Pliocene. The obtained rotation senses and amounts indicate slight (around 20°) counter-clockwise rotations distributed uniformly almost whole SW Anatolia and there is no change in the rotation senses and amounts on either side of the FBFZ implying no differential rotation within the zone. Additionally, the slickenside pitches and constructed paleostress configurations, along the so called FBFZ and also within the 300 km diameter of the proposed fault zone, indicated that almost all the faults, oriented parallel to subparallel to the zone, are normal in character. The fault slip measurements are also consistent with earthquake focal mechanisms suggesting active extension in the region. We have not encountered any significant strike-slip motion in the region to support presence and transcurrent nature of the FBFZ. On the contrary, the region is dominated by extensional deformation and strike-slip components are observed only on the NW-SE striking faults which are transfer faults that accommodated extension and normal motion. Therefore, we claim that the sinistral Fethiye Burdur Fault (Zone) is a myth and there is no tangible

  20. Mantle strength of the San Andreas fault system and the role of mantle-crust feedbacks

    NARCIS (Netherlands)

    Chatzaras, V.; Tikoff, B.; Newman, J.; Withers, A.C.; Drury, M.R.

    2015-01-01

    In lithospheric-scale strike-slip fault zones, upper crustal strength is well constrained from borehole observations and fault rock deformation experiments, but mantle strength is less well known. Using peridotite xenoliths, we show that the upper mantle below the San Andreas fault system

  1. Insights into the 3D architecture of an active caldera ring-fault at Tendürek volcano through modeling of geodetic data

    KAUST Repository

    Vasyura-Bathke, Hannes

    2015-04-28

    The three-dimensional assessment of ring-fault geometries and kinematics at active caldera volcanoes is typically limited by sparse field, geodetic or seismological data, or by only partial ring-fault rupture or slip. Here we use a novel combination of spatially dense InSAR time-series data, numerical models and sand-box experiments to determine the three-dimensional geometry and kinematics of a sub-surface ring-fault at Tendürek volcano in Turkey. The InSAR data reveal that the area within the ring-fault not only subsides, but also shows substantial westward-directed lateral movement. The models and experiments explain this as a consequence of a ‘sliding-trapdoor’ ring-fault architecture that is mostly composed of outward-inclined reverse segments, most markedly so on the volcano\\'s western flanks but includes inward-inclined normal segments on its eastern flanks. Furthermore, the model ring-fault exhibits dextral and sinistral strike-slip components that are roughly bilaterally distributed onto its northern and southern segments, respectively. Our more complex numerical model describes the deformation at Tendürek better than an analytical solution for a single rectangular dislocation in a half-space. Comparison to ring-faults defined at Glen Coe, Fernandina and Bárðarbunga calderas suggests that ‘sliding-trapdoor’ ring-fault geometries may be common in nature and should therefore be considered in geological and geophysical interpretations of ring-faults at different scales worldwide.

  2. 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.

  3. Origin and model of transform faults in the Okinawa Trough

    Science.gov (United States)

    Liu, Bo; Li, Sanzhong; Jiang, Suhua; Suo, Yanhui; Guo, Lingli; Wang, Yongming; Zhang, Huixuan

    2017-06-01

    Transform faults in back-arc basins are the key to revealing the opening and development of marginal seas. The Okinawa Trough (OT) represents an incipient and active back-arc or marginal sea basin oriented in a general NE-SW direction. To determine the strikes and spatial distribution of transform faults in the OT, this paper dissects the NW- and NNE-SN-trending fault patterns on the basis of seismic profiles, gravity anomalies and region geological data. There are three main NW-trending transpressional faults in the OT, which are the seaward propagation of NW-trending faults in the East China Continent. The NNE-SN-trending faults with right-stepping distribution behave as right-lateral shearing. The strike-slip pull-apart process or transtensional faulting triggered the back-arc rifting or extension, and these faults evolved into transform faults with the emergence of oceanic crust. Thus, the transform fault patterns are inherited from pre-existing oblique transtensional faults at the offsets between rifting segments. Therefore, the OT performs the oblique spreading mechanism similar to nascent oceans such as the Red Sea and Gulf of Aden.

  4. Geometry of the Gerede Segment, North Anatolian Fault Zone, Turkey

    Science.gov (United States)

    Caglayan, A.; ISIK, V.

    2012-12-01

    The North Anatolian Fault Zone (NAFZ) is an active dextral strike-slip fault zone in northern Turkey. The NAFZ is approximately 1200 km in length which extends from Karliova in the east and to reach as far as the Gulf of Saros in the west. The NAFZ becomes wider geometry from east to west which are characterized by 9 destructive earthquake of Ms>7 in the 20th century. An earthquake on 1944 February 1 (Ms 7,3) caused 180 km long surface rupture associated with 2-6.5 m of right-lateral slip between Bayramören in the east and Abant Lake in the west along the NAFZ, which is called the Gerede Segment. This study describes internal geometrical characteristics and deformation mechanism of faults with fault surfaces in the Gerede Segment. The faults along the segment variously cut across Mesozoic-Cenozoic basement rocks and Quaternary alluvium deposits. They juxtapose not only different units of basement but also basement rocks and alluvium. We select typical fault surface that have been formed the best exposures in limestone in different locality, which define exhumed main faults along the segment. These faults strike N70°-80°E and dip 50°-85°NW. Slickenlines on these fault surface plunge shallowly to the NE and/or SW. Fault surface include brittle kinematic indicators indicating right-lateral strike-slip displacements. Some typical Riedel shear fractures (R- and P-fractures) around the main faults also show dextral displacements. Along the main faults two main architectural elements including fault core and fault damage zone is typical. The fault damage zones of these faults are characterized by both fault-related fracturing and fluid-assisted deformation processes. Although breccia is common fault rock in fault zones, gouge and cataclasite are seen in variable exposures. We have defined crackle, mosaic and chaotic type breccias using clast-size and clast proportion. Rock fragments within breccias have occurred mm-cm scale from angular to rounded clast. Sub

  5. Study on seismic hazard assessment of large active fault systems. Evolution of fault systems and associated geomorphic structures: fault model test and field survey

    International Nuclear Information System (INIS)

    Ueta, Keichi; Inoue, Daiei; Miyakoshi, Katsuyoshi; Miyagawa, Kimio; Miura, Daisuke

    2003-01-01

    Sandbox experiments and field surveys were performed to investigate fault system evolution and fault-related deformation of ground surface, the Quaternary deposits and rocks. The summary of the results is shown below. 1) In the case of strike-slip faulting, the basic fault sequence runs from early en echelon faults and pressure ridges through linear trough. The fault systems associated with the 2000 western Tottori earthquake are shown as en echelon pattern that characterize the early stage of wrench tectonics, therefore no thoroughgoing surface faulting was found above the rupture as defined by the main shock and aftershocks. 2) Low-angle and high-angle reverse faults commonly migrate basinward with time, respectively. With increasing normal fault displacement in bedrock, normal fault develops within range after reverse fault has formed along range front. 3) Horizontal distance of surface rupture from the bedrock fault normalized by the height of the Quaternary deposits agrees well with those of model tests. 4) Upward-widening damage zone, where secondary fractures develop, forms in the handing wall side of high-angle reverse fault at the Kamioka mine. (author)

  6. 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...

  7. 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...

  8. Development, Interaction and Linkage of Normal Fault Segments along the 100-km Bilila-Mtakataka Fault, Malawi

    Science.gov (United States)

    Fagereng, A.; Hodge, M.; Biggs, J.; Mdala, H. S.; Goda, K.

    2016-12-01

    Faults grow through the interaction and linkage of isolated fault segments. Continuous fault systems are those where segments interact, link and may slip synchronously, whereas non-continuous fault systems comprise isolated faults. As seismic moment is related to fault length (Wells and Coppersmith, 1994), understanding whether a fault system is continuous or not is critical in evaluating seismic hazard. Maturity may be a control on fault continuity: immature, low displacement faults are typically assumed to be non-continuous. Here, we study two overlapping, 20 km long, normal fault segments of the N-S striking Bilila-Mtakataka fault, Malawi, in the southern section of the East African Rift System. Despite its relative immaturity, previous studies concluded the Bilila-Mtakataka fault is continuous for its entire 100 km length, with the most recent event equating to an Mw8.0 earthquake (Jackson and Blenkinsop, 1997). We explore whether segment geometry and relationship to pre-existing high-grade metamorphic foliation has influenced segment interaction and fault development. Fault geometry and scarp height is constrained by DEMs derived from SRTM, Pleiades and `Structure from Motion' photogrammetry using a UAV, alongside direct field observations. The segment strikes differ on average by 10°, but up to 55° at their adjacent tips. The southern segment is sub-parallel to the foliation, whereas the northern segment is highly oblique to the foliation. Geometrical surface discontinuities suggest two isolated faults; however, displacement-length profiles and Coulomb stress change models suggest segment interaction, with potential for linkage at depth. Further work must be undertaken on other segments to assess the continuity of the entire fault, concluding whether an earthquake greater than that of the maximum instrumentally recorded (1910 M7.4 Rukwa) is possible.

  9. Influence of host lithofacies on fault rock variation in carbonate fault zones: A case study from the Island of Malta

    Science.gov (United States)

    Michie, E. A. H.

    2015-07-01

    Relatively few studies have examined fault rock microstructures in carbonates. Understanding fault core production helps predict the hydraulic behaviour of faults and the potential for reservoir compartmentalisation. Normal faults on Malta, ranging from fracture networks that develop into breccias. Alternatively, this lithofacies is commonly recrystallised. In contrast, in the coarse-grained, heterogeneous grain-dominated carbonates the development of faulting is characterised by localised deformation, creating protocataclasite and cataclasite fault rocks. Cementation also occurs within some grain-dominated carbonates close to and on slip surfaces. Fault rock variation is a function of displacement as well as juxtaposed lithofacies. An increase in fault rock variability is observed at higher displacements, potentially creating a more transmissible fault, which opposes what may be expected in siliciclastic and crystalline faults. Significant heterogeneity in the fault rock types formed is likely to create variable permeability along fault-strike, potentially allowing across-fault fluid flow. However, areas with homogeneous fault rocks may generate barriers to fluid flow.

  10. Strong Algerian Earthquake Strikes Near Capital City

    Science.gov (United States)

    Ayadi, A.; Maouche, S.; Harbi, A.; Meghraoui, M.; Beldjoudi, H.; Oussadou, F.; Mahsas, A.; Benouar, D.; Heddar, A.; Rouchiche, Y.; Kherroubi, A.; Frogneux, M.; Lammali, K.; Benhamouda, F.; Sebaï, A.; Bourouis, S.; Alasset, P. J.; Aoudia, A.; Cakir, Z.; Merahi, M.; Nouar, O.; Yelles, A.; Bellik, A.; Briole, P.; Charade, O.; Thouvenot, F.; Semane, F.; Ferkoul, A.; Deramchi, A.; Haned, S. A.

    On 21 May 2003, a damaging earthquake of Mw 6.8 struck the region of Boumerdes 40 km east of Algiers in northern Algeria (Figure 1). The mainshock, which lasted ~ 36-40 s, had devastating effects and claimed about 2300 victims, caused more than 11,450 injuries, and left about 200,000 people homeless. It destroyed and seriously damaged around 180,000 housing units and 6000 public buildings with losses estimated at $5 billion. The mainshock was widely felt within a radius of ~ 400 km in Algeria. To the north, the earthquake was felt in southeastern Spain, including the Balearic Islands, and also in Sardinia and in southern France. The mainshock location, which was calculated at 36.91°N, 3.58°E (15 km offshore of Zemmouri; Figure 1), and the local magnitude (Md 6.4) are from seismic records of local stations. International seismological centers obtained Mw 6.8 (NEIC) with a thrust focal mechanism solution and 1.83 × 1026 dyne.cm for the seismic moment. A sequence of aftershocks affected the epicentral area with two strong shocks reaching Mw 5.8 on 27 and 29 May 2003. Field investigations allowed us to assign a maximum intensity X (European Macroseismic Scale 98) and to report rockfalls, minor surface cracks, and liquefaction phenomena. The mainshock was not associated with inland surface faulting, but one of the most striking coseismic effects is the coastal uplift and the backwash along the littoral of the Mitidja basin.

  11. How fault evolution changes strain partitioning and fault slip rates in Southern California: Results from geodynamic modeling

    Science.gov (United States)

    Ye, Jiyang; Liu, Mian

    2017-08-01

    In Southern California, the Pacific-North America relative plate motion is accommodated by the complex southern San Andreas Fault system that includes many young faults (faults and their impact on strain partitioning and fault slip rates are important for understanding the evolution of this plate boundary zone and assessing earthquake hazard in Southern California. Using a three-dimensional viscoelastoplastic finite element model, we have investigated how this plate boundary fault system has evolved to accommodate the relative plate motion in Southern California. Our results show that when the plate boundary faults are not optimally configured to accommodate the relative plate motion, strain is localized in places where new faults would initiate to improve the mechanical efficiency of the fault system. In particular, the Eastern California Shear Zone, the San Jacinto Fault, the Elsinore Fault, and the offshore dextral faults all developed in places of highly localized strain. These younger faults compensate for the reduced fault slip on the San Andreas Fault proper because of the Big Bend, a major restraining bend. The evolution of the fault system changes the apportionment of fault slip rates over time, which may explain some of the slip rate discrepancy between geological and geodetic measurements in Southern California. For the present fault configuration, our model predicts localized strain in western Transverse Ranges and along the dextral faults across the Mojave Desert, where numerous damaging earthquakes occurred in recent years.

  12. Strikes in Serbia since 2000 to 2005

    Directory of Open Access Journals (Sweden)

    Novaković Nada

    2005-01-01

    Full Text Available 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 every power dislike strikes and is ready to do everything to diminish them. Main reason lies in the class nature of social conflict that underlie them. Main processes that underlie strike phenomena in Serbia since 2000. are the processes of originally capital accumulation. These bring about the formation of new capitalist class and proletariat of all professions. Author gives a brief analysis of privatization process, as well as of restructuring of public sector and deregulation of economy trying to show the role of all of it in origins of strikes. Main conclusion is that there are large number of strikes in all parts of society, that are well organized, with support of one or more trade unions. For these in power they are factor of obstacle on the way of successful transition. As for the reasons and outcomes these strikes are akin to the strikes at the beginning of 19th century.

  13. Third-party support for strike action.

    Science.gov (United States)

    Kelloway, E Kevin; Francis, Lori; Catano, Victor M; Dupré, Kathryne E

    2008-07-01

    Labor strikes are often seen as battles for public support. Members of the public are asked to show respect for a strike by refusing to cross the picket line or by joining strikers on the picket line. Such public support may affect the morale of strikers and influence the strike's duration. Despite the perceived importance of the public in labor disputes, members of third parties have not been considered in previous strike research. In 2 studies, the authors show that a new measure of third-party strike support is unidimensional and highly reliable. In both cases, union attitudes and perceptions of distributive justice were significant predictors of support for strike action. Those who are more supportive of unions in general and believe that the contract offered to the strikers was unfair were more likely to support the strike by engaging in such actions as conversing with strikers, writing letters, and refusing to cross the picket line.

  14. Evolution of fault activity reflecting the crustal deformation: Insights from crustal stress and fault orientations in the northeast-southwest Japan

    Science.gov (United States)

    Miyakawa, A.; Otsubo, M.

    2015-12-01

    We evaluated fault activity in northeast- southwest Japan based on the regional stress and the fault orientation field for both active faults and inactive faults (here, an inactive fault is a fault which activity has not been identified in Quaternary). The regional stress field was calculated using the stress inversion method [Hardebeck and Michael, 2006] applied to earthquake focal mechanisms in the northeast-southwest Japan. The locations and orientations (i.e., strike and dip, assuming a planar fault geometry) of active faults in the study area were obtained from the Active Fault Database of Japan and inactive faults from a database compiled by Kosaka et al. [2011]. We employed slip tendency analysis [Morris et al., 1996] to evaluate the likelihood of fault slip. The values of the slip tendency is generally higher along active faults than along inactive faults. The difference between the slip tendencies of active and inactive faults reflects the difference in their activities. Furthermore the high slip tendency observed for some inactive faults suggests their high activity. These high slip tendencies imply that they have potential to be active. We propose the temporal evolution from inactive to active faulting during long-term crustal deformation to explain the potential for fault activity along inactive faults. When a region undergoes the transition from inactive to active faulting, potential active faults are observed as inactive faults with a high Part of this findig have been submitted to Tectonics (AGU Journal) (2015-07-27). We will presentate some new findings.slip tendency. The average slip tendency of inactive faults gradually increases from northeast to southwest Japan, because a relatively large number of inactive faults in southwest Japan have a high slip tendency. The representative deformation zones in Japan shows a relationship with the observed spatial variations in the evolution from inactive to active faulting. This study was supported by MEXT

  15. High-Resolution Aeromagnetic Survey To Image Shallow Faults, Poncha Springs and Vicinity, Chaffee County, Colorado

    Science.gov (United States)

    Grauch, V.J.S.; Drenth, Benjamin J.

    2009-01-01

    High-resolution aeromagnetic data were acquired over the town of Poncha Springs and areas to the northwest to image faults, especially where they are concealed. Because this area has known hot springs, faults or fault intersections at depth can provide pathways for upward migration of geothermal fluids or concentrate fracturing that enhances permeability. Thus, mapping concealed faults provides a focus for follow-up geothermal studies. Fault interpretation was accomplished by synthesizing interpretative maps derived from several different analytical methods, along with preliminary depth estimates. Faults were interpreted along linear aeromagnetic anomalies and breaks in anomaly patterns. Many linear features correspond to topographic features, such as drainages. A few of these are inferred to be fault-related. The interpreted faults show an overall pattern of criss-crossing fault zones, some of which appear to step over where they cross. Faults mapped by geologists suggest similar crossing patterns in exposed rocks along the mountain front. In low-lying areas, interpreted faults show zones of west-northwest-, north-, and northwest-striking faults that cross ~3 km (~2 mi) west-northwest of the town of Poncha Springs. More easterly striking faults extend east from this juncture. The associated aeromagnetic anomalies are likely caused by magnetic contrasts associated with faulted sediments that are concealed less than 200 m (656 ft) below the valley floor. The faults may involve basement rocks at greater depth as well. A relatively shallow (hot springs and south of the town of Poncha Springs.

  16. Missing link between the Hayward and Rodgers Creek faults

    Science.gov (United States)

    Watt, Janet; Ponce, David A.; Parsons, Thomas E.; Hart, Patrick E.

    2016-01-01

    The next major earthquake to strike the ~7 million residents of the San Francisco Bay Area will most likely result from rupture of the Hayward or Rodgers Creek faults. Until now, the relationship between these two faults beneath San Pablo Bay has been a mystery. Detailed subsurface imaging provides definitive evidence of active faulting along the Hayward fault as it traverses San Pablo Bay and bends ~10° to the right toward the Rodgers Creek fault. Integrated geophysical interpretation and kinematic modeling show that the Hayward and Rodgers Creek faults are directly connected at the surface—a geometric relationship that has significant implications for earthquake dynamics and seismic hazard. A direct link enables simultaneous rupture of the Hayward and Rodgers Creek faults, a scenario that could result in a major earthquake (M = 7.4) that would cause extensive damage and loss of life with global economic impact.

  17. Missing link between the Hayward and Rodgers Creek faults.

    Science.gov (United States)

    Watt, Janet; Ponce, David; Parsons, Tom; Hart, Patrick

    2016-10-01

    The next major earthquake to strike the ~7 million residents of the San Francisco Bay Area will most likely result from rupture of the Hayward or Rodgers Creek faults. Until now, the relationship between these two faults beneath San Pablo Bay has been a mystery. Detailed subsurface imaging provides definitive evidence of active faulting along the Hayward fault as it traverses San Pablo Bay and bends ~10° to the right toward the Rodgers Creek fault. Integrated geophysical interpretation and kinematic modeling show that the Hayward and Rodgers Creek faults are directly connected at the surface-a geometric relationship that has significant implications for earthquake dynamics and seismic hazard. A direct link enables simultaneous rupture of the Hayward and Rodgers Creek faults, a scenario that could result in a major earthquake ( M = 7.4) that would cause extensive damage and loss of life with global economic impact.

  18. Loading of the San Andreas fault by flood-induced rupture of faults beneath the Salton Sea

    Science.gov (United States)

    Brothers, Daniel; Kilb, Debi; Luttrell, Karen; Driscoll, Neal W.; Kent, Graham

    2011-01-01

    The southern San Andreas fault has not experienced a large earthquake for approximately 300 years, yet the previous five earthquakes occurred at ~180-year intervals. Large strike-slip faults are often segmented by lateral stepover zones. Movement on smaller faults within a stepover zone could perturb the main fault segments and potentially trigger a large earthquake. The southern San Andreas fault terminates in an extensional stepover zone beneath the Salton Sea—a lake that has experienced periodic flooding and desiccation since the late Holocene. Here we reconstruct the magnitude and timing of fault activity beneath the Salton Sea over several earthquake cycles. We observe coincident timing between flooding events, stepover fault displacement and ruptures on the San Andreas fault. Using Coulomb stress models, we show that the combined effect of lake loading, stepover fault movement and increased pore pressure could increase stress on the southern San Andreas fault to levels sufficient to induce failure. We conclude that rupture of the stepover faults, caused by periodic flooding of the palaeo-Salton Sea and by tectonic forcing, had the potential to trigger earthquake rupture on the southern San Andreas fault. Extensional stepover zones are highly susceptible to rapid stress loading and thus the Salton Sea may be a nucleation point for large ruptures on the southern San Andreas fault.

  19. Fault type predictions from stress distributions on planetary surfaces - Importance of fault initiation depth

    Science.gov (United States)

    Golombek, M. P.

    1985-01-01

    The prediction of fault type on planetary surfaces from model stresses calculated at depth is discussed. These fault-type predictions yield different faults than those predicted using the surface criteria commonly employed in geophysical models. For elastic-plate flexure models of mascon loading on the moon, stresses calculated at the surface predict the occurrence of strike-slip faulting at the radial distance where grabens are found. Normal faults bounding lunar grabens and thrust faults responsible for wrinkle ridges are analyzed. It is found that the former initiate at the mechanical discontinuity that separates the breccia of the megaregolith from in situ fractured rock and that the latter initiate at the mechanical discontinuity between basalt layers and the underlying basin floor. The difference between elastic constants for the outer few kilometers of brecciated megaregolith and the underlying lunar lithosphere are evaluated. Superposing nonisotropic stresses resulting from the weight of overburden to the depth of the relevant mechanical discontinuity yield stresses that predict wrinkle ridges in the basin centers and grabens outside the basin margin, and eliminate the predicted zone of strike-slip faults.

  20. Late Pleistocene dip-slip faulting along the Dunajec Fault, West Carpathians: Insights from alluvial sediments

    Science.gov (United States)

    Olszak, Janusz

    2017-10-01

    This paper presents vertical movement along the Dunajec Fault during the Late Pleistocene and suggests Quaternary tectonic reactivation of diagonal strike-slip faults and their transformation into dip-slip faults in the West Carpathians. Optically stimulated luminescence (OSL) dating of Pleistocene alluvial sediments of the Dunajec and the Ochotnica rivers was employed to determine the time range of deposition of these sediments. Vertical and spatial distribution of the obtained OSL ages imply that the alluvial sediments were affected by the Dunajec Fault, which appears to have acted as a scissor fault during the Late Pleistocene. The results contribute to the discussion on the recent evolution of the Carpathians, and may support the concept of extensional collapse of the orogen.

  1. Along-strike Variations in Active Strain Accumulation in the Northwest Himalaya

    Science.gov (United States)

    Morell, K. D.; Ahmad, T.; Sandiford, M.; Codilean, A. T.; Fulop, R. H.

    2015-12-01

    The spatial distribution of channel steepness, erosion rate, and physiographic data highlight pronounced along-strike changes in active strain accumulation in the northwest Himalaya. In particular, the data suggest that the mid-crustal ramp of the Main Himalayan Thrust could merge along-strike with an active portion of the Main Boundary Thrust near longitude ~77º E. This along-strike change in active fault geometry also coincides with the lateral termination of both lesser and greater Himalayan sequences, a significant reduction in total shortening within the wedge, and pronounced variations in regional seismicity. Recent activity along extensional structures in the high Himalaya of this same region appears to have led to significant reorganization, modification and capture of the Sutlej River basin, one of the largest Himalayan river systems. Given the recent 2015 Gorkha earthquake along a comparable section ~500-km along strike, these new constraints on active fault architecture could have regional implications for how strain is partitioned along seismogenic faults in the northwest Himalaya.

  2. 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

  3. Equivalent strike-slip earthquake cycles in half-space and lithosphere-asthenosphere earth models

    Science.gov (United States)

    Savage, J.C.

    1990-01-01

    By virtue of the images used in the dislocation solution, the deformation at the free surface produced throughout the earthquake cycle by slippage on a long strike-slip fault in an Earth model consisting of an elastic plate (lithosphere) overlying a viscoelastic half-space (asthenosphere) can be duplicated by prescribed slip on a vertical fault embedded in an elastic half-space. Inversion of 1973-1988 geodetic measurements of deformation across the segment of the San Andreas fault in the Transverse Ranges north of Los Angeles for the half-space equivalent slip distribution suggests no significant slip on the fault above 30 km and a uniform slip rate of 36 mm/yr below 30 km. One equivalent lithosphere-asthenosphere model would have a 30-km thick lithosphere and an asthenosphere relaxation time greater than 33 years, but other models are possible. -from Author

  4. Internal structure of fault zones in geothermal reservoirs: Examples from palaeogeothermal fields and potential host rocks

    Science.gov (United States)

    Leonie Philipp, Sonja; Reyer, Dorothea; Meier, Silke; Bauer, Johanna F.; Afşar, Filiz

    2014-05-01

    Fault zones commonly have great effects on fluid transport in geothermal reservoirs. During fault slip all the pores and small fractures that meet with the slip plane become interconnected so that the inner part of the fault, the fault core, consisting of breccia or gouge, may suddenly develop a very high permeability. This is evidenced, for example by networks of mineral veins in deeply eroded fault zones in palaeogeothermal fields. Inactive faults, however, may have low permeabilities and even act as flow barriers. In natural and man-made geothermal reservoirs, the orientation of fault zones in relation to the current stress field and their internal structure needs be known as accurately as possible. One reason is that the activity of the fault zone depends on its angle to the principal stress directions. Another reason is that the outer part of a fault zone, the damage zone, comprises numerous fractures of various sizes. Here we present field examples of faults, and associated joints and mineral veins, in palaeogeothermal fields, and potential host rocks for man-made geothermal reservoirs, respectively. We studied several localities of different stratigraphies, lithologies and tectonic settings: (1) 58 fault zones in 22 outcrops from Upper Carboniferous to Upper Cretaceous in the Northwest German Basin (siliciclastic, carbonate and volcanic rocks); (2) 16 fault zones in 9 outcrops in Lower Permian to Middle Triassic (mainly sandstone, limestone and granite) in the Upper Rhine Graben; and (3) 74 fault zones in two coastal sections of Upper Triassic and Lower Jurassic age (mudstones and limestone-marl alternations) in the Bristol Channel Basin, UK. (1) and (2) are outcrop analogues of geothermal reservoir horizons, (3) represent palaeogeothermal fields with mineral veins. The field studies in the Northwest German Basin (1) show pronounced differences between normal-fault zones in carbonate and clastic rocks. In carbonate rocks clear damage zones occur that are

  5. Active Fault Geometry and Crustal Deformation Along the San Andreas Fault System Through San Gorgonio Pass, California: The View in 3D From Seismicity

    Science.gov (United States)

    Nicholson, C.; Hauksson, E.; Plesch, A.

    2012-12-01

    Understanding the 3D geometry and deformation style of the San Andreas fault (SAF) is critical to accurate dynamic rupture and ground motion prediction models. We use 3D alignments of hypocenter and focal mechanism nodal planes within a relocated earthquake catalog (1981-2011) [Hauksson et al., 2012] to develop improved 3D fault models for active strands of the SAF and adjacent secondary structures. Through San Gorgonio Pass (SGP), earthquakes define a mechanically layered crust with predominantly high-angle strike-slip faults in the upper ~10 km, while at greater depth, intersecting sets of strike-slip, oblique slip and low-angle thrust faults define a wedge-shaped volume deformation of the lower crust. In some places, this interface between upper and lower crustal deformation may be an active detachment fault, and may have controlled the down-dip extent of recent fault rupture. Alignments of hypocenters and nodal planes define multiple principal slip surfaces through SGP, including a through-going steeply-dipping predominantly strike-slip Banning fault strand at depth that upward truncates a more moderately dipping (40°-50°) blind, oblique North Palm Springs fault. The North Palm Springs fault may be the active down-dip extension of the San Gorgonio Pass thrust offset at depth by the principal, through-going Banning strand. In the northern Coachella Valley, seismicity indicates that the Garnet Hill and Banning fault strands are most likely sub-parallel and steeply dipping (~70°NE) to depths of 8-10 km, where they intersect and merge with a stack of moderately dipping to low-angle oblique thrust faults. Gravity and water well data confirm that these faults are sub-parallel and near vertical in the upper 2-3 km. Although the dense wedge of deep seismicity below SGP and largely south of the SAF contains multiple secondary fault sets of different orientations, the predominant fault set appears to be a series of en echelon NW-striking oblique strike-slip faults

  6. Slip-weakening distance and energy budget inferred from near-fault ground deformation during the 2016 Mw7.8 Kaikōura earthquake

    Science.gov (United States)

    Kaneko, Yoshihiro; Fukuyama, Eiichi; Hamling, Ian James

    2017-05-01

    The 2016 M7.8 Kaikōura (New Zealand) earthquake struck the east coast of the northern South Island, resulting in strong ground shaking and large surface fault slip. Since the earthquake was well recorded by a local strong-motion seismic network, near-fault data may provide direct measurements of dynamic parameters associated with the fault-weakening process. Here we estimate a proxy for slip-weakening distance Dc '', defined as double the fault-parallel displacement at the time of peak ground velocity, from accelerograms recorded at a near-fault station. Three-component ground displacements were recovered from the double numerical integration of accelerograms, and the corresponding final displacements are validated against coseismic displacement from geodetic data. The estimated Dc '' is 4.9 m at seismic station KEKS located ˜2.7 km from a segment of the Kekerengu fault where large surface fault slip (˜12 m) has been observed. The inferred Dc '' is the largest value ever estimated from near-fault strong motion data, yet it appears to follow the scaling of Dc '' with final slip for several large strike-slip earthquakes. The energy budget of the M7.8 Kaikōura earthquake inferred from the scaling of Dc '' with final slip indicates that a large amount of energy was dissipated by on- and off-fault inelastic deformation during the propagation of the earthquake rupture, resulting in a slower average rupture speed (≲2.0 km/s).

  7. Role of seismogenic processes in fault-rock development: An example from Death Valley, California

    Science.gov (United States)

    Pavlis, Terry L.; Serpa, Laura F.; Keener, Charles

    1993-03-01

    Fault rocks developed along the Mormon Point turtleback of southern Death Valley suggest that a jog in the oblique-slip Death Valley fault zone served as an ancient seismic barrier, where dominantly strike-slip ruptures were terminated at a dilatant jog. Dramatic spatial variations in fault-rock thickness and type within the bend are interpreted as the products of: (1) fault "overshoot," in which planar ruptures bypass the intersection of the two faults composing the bend and slice into the underlying footwall; and (2) implosion brecciation, in which coseismic ruptures arrested at a releasing bend in the fault lead to catastrophic collapse brecciation, fluid influx, and mineralization.

  8. RECENT GEODYNAMICS OF FAULT ZONES: FAULTING IN REAL TIME SCALE

    Directory of Open Access Journals (Sweden)

    Yu. O. Kuzmin

    2014-01-01

    Full Text Available Recent deformation processes taking place in real time are analyzed on the basis of data on fault zones which were collected by long-term detailed geodetic survey studies with application of field methods and satellite monitoring.A new category of recent crustal movements is described and termed as parametrically induced tectonic strain in fault zones. It is shown that in the fault zones located in seismically active and aseismic regions, super intensive displacements of the crust (5 to 7 cm per year, i.e. (5 to 7·10–5 per year occur due to very small external impacts of natural or technogenic / industrial origin.The spatial discreteness of anomalous deformation processes is established along the strike of the regional Rechitsky fault in the Pripyat basin. It is concluded that recent anomalous activity of the fault zones needs to be taken into account in defining regional regularities of geodynamic processes on the basis of real-time measurements.The paper presents results of analyses of data collected by long-term (20 to 50 years geodetic surveys in highly seismically active regions of Kopetdag, Kamchatka and California. It is evidenced by instrumental geodetic measurements of recent vertical and horizontal displacements in fault zones that deformations are ‘paradoxically’ deviating from the inherited movements of the past geological periods.In terms of the recent geodynamics, the ‘paradoxes’ of high and low strain velocities are related to a reliable empirical fact of the presence of extremely high local velocities of deformations in the fault zones (about 10–5 per year and above, which take place at the background of slow regional deformations which velocities are lower by the order of 2 to 3. Very low average annual velocities of horizontal deformation are recorded in the seismic regions of Kopetdag and Kamchatka and in the San Andreas fault zone; they amount to only 3 to 5 amplitudes of the earth tidal deformations per year.A ‘fault

  9. The characteristics of the western extension of the Karakax fault in NW Tibet and its tectonic implications

    Science.gov (United States)

    Ge, C.; Liu, D.; Li, H.; Zheng, Y.; Pan, J.

    2017-12-01

    The Karakax strike-slip fault, located in northwest Tibet, is a mature deformation belt with a long-time evolutionary history, which is also active at present and plays an important role in the tectonic deformation of the northwestern Tibetan Plateau. Nowadays, most geologists consider that the Karakax fault is generally east-west striking along the Karakax river valley, and northwest striking until to the Tashkorgan in the Mazar area. However, an ENE-WSW fault was identified at the Mazar area, which sited at the bend of the Karakax fault, we named this fault as the Matar fault. Via the detailed geological survey, the similar geometry and kinematic characteristics were identified between the Karakax and Matar faults: (1) The similar fault zone scale(Karakax:90 300m; Matar:100 220m); (2) The similar preferred orientation (nearly EW) of the stretching lineations and foliations; (3) All the fault planes of the both faults have a high dip angle and is nearly EW striking; (4) Lots of ductile deformations, such as σ-type quartz rotational mortar, S-C fabric, symmetric drag fold and so on, indicated that the Matar fault is a right-lateral strike-slip and thrust fault during the early ductile deformation stage; (5) the deluvium, sheared by Matar fault, indicated that the Matar fault has already transformed into a left-lateral strike-slip fault during the later brittle deformation stage. All the above showed that the Matar fault has a similar geometry and kinematic characteristics with the Karakax fault, and the former is the probable the western extension of the latter. Moreover, the form of the Karakax-Matar fault may had an impact to the geomorphology of the west Kunlun-Pamir area, such as the strike of the moutains and faults. considering the age of west Kunlun mountains uplifting and Karakax fault activating, we regard that the Matar fault (the westward extension of Karakax fault) may contributes much in forming the modern geomorphology features of the west Kunlun

  10. Spatio-temporal trends in normal-fault segmentation recorded by low-temperature thermochronology: Livingstone fault scarp, Malawi Rift, East African Rift System

    Science.gov (United States)

    Mortimer, Estelle; Kirstein, Linda A.; Stuart, Finlay M.; Strecker, Manfred R.

    2016-12-01

    The evolution of through-going normal-fault arrays from initial nucleation to growth and subsequent interaction and mechanical linkage is well documented in many extensional provinces. Over time, these processes lead to predictable spatial and temporal variations in the amount and rate of displacement accumulated along strike of individual fault segments, which should be manifested in the patterns of footwall exhumation. Here, we investigate the along-strike and vertical distribution of low-temperature apatite (U-Th)/He (AHe) cooling ages along the bounding fault system, the Livingstone fault, of the Karonga Basin of the northern Malawi Rift. The fault evolution and linkage from rift initiation to the present day has been previously constrained through investigations of the hanging wall basin fill. The new cooling ages from the footwall of the Livingstone fault can be related to the adjacent depocentre evolution and across a relay zone between two palaeo-fault segments. Our data are complimented by published apatite fission-track (AFT) data and reveal significant variation in rock cooling history along-strike: the centre of the footwall yields younger cooling ages than the former tips of earlier fault segments that are now linked. This suggests that low-temperature thermochronology can detect fault interactions along strike. That these former segment boundaries are preserved within exhumed footwall rocks is a function of the relatively recent linkage of the system. Our study highlights that changes in AHe (and potentially AFT) ages associated with the along-strike displacement profile can occur over relatively short horizontal distances (of a few kilometres). This is fundamentally important in the assessment of the vertical cooling history of footwalls in extensional systems: temporal differences in the rate of tectonically driven exhumation at a given location along fault strike may be of greater importance in controlling changes in rates of vertical exhumation

  11. The tsunami-like sea level disturbance in Crotone harbor, Italy, after the Mw6.5 strike-slip earthquake of 17 November 2015 in Lefkada Isl., Ionian Sea, Greece

    Science.gov (United States)

    Novikova, Tatyana; Annunziato, Alessandro; Charalampakis, Marinos; Romano, Fabrizio; Volpe, Manuela; Tonini, Roberto; Gerardinger, Andrea; Papadopoulos, Gerassimos A.

    2016-04-01

    On 17 November 2015 an Mw6.5 earthquake ruptured offshore Lefkada Isl. in Ionian Sea, Greece, causing two human victims, minor damage and several ground failures including coastal landslides. Fault plane solutions released by CMT/Harvard, NOA and other institutes have indicated that the faulting style was strike-slip right-lateral, which is quite typical for the area, as for example, the Mw6.3 event that occurred on August 14, 2003, in exactly the same fault zone. In spite of the very low tsunami potential commonly associated to this faulting mechanism, a tsunami-like sea level change was recorded after the earthquake by one tide-gauge in the Crotone harbor, Italy. Preliminary tsunami numerical simulations were performed to reproduce the observed signal. The spectral analysis of the synthetic mareograms close to the entrance of the harbor shows the presence of some peaks that could justify the relation between the natural port resonance and the observed wave amplification. Of particular interest is the coupling between the tsunami energy and the natural modes of basin oscillation enhancing tsunami wave amplitude in harbors through resonance, as shown in some historical events in the Mediterranean Sea and elsewhere. This research is a contribution to the EU-FP7 tsunami research project ASTARTE (Assessment, Strategy And Risk Reduction for Tsunamis in Europe), grant agreement no: 603839, 2013-10-30.

  12. 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.

  13. Structure of the Newport-Inglewood/Rose Canyon and Palos Verdes Fault Zones and Implications for Current Fault Models

    Science.gov (United States)

    Sahakian, V. J.; Bormann, J. M.; Klotsko, S.; Holmes, J. J.; Driscoll, N. W.; Harding, A. J.; Kent, G.; Wesnousky, S. G.

    2014-12-01

    Faulting in the Inner California Borderlands is complex. In the past, this region has undergone various deformational events such as extensional and rotational deformation to variable strike-slip deformation; this has imparted the geomorphology and fault structures observed offshore Southern California. Several hypotheses have been proposed to explain the current fault structures and the hazards they pose to populated coastal regions. The geometry and architecture of these structures can have significant implications for ground motions in the event of a rupture, and therefore impact working models of hazard assessment. Here, focusing on the Newport-Inglewood/Rose Canyon (NI/RC) and Palos Verdes (PV) fault zones, we use new and existing multibeam, CHIRP and Multi-Channel Seismic (MCS) data to describe the geometry of the fault system. We interpret reprocessed (prestack time migration) MCS data collected in 1979, 1986, and 2006 as well as newly acquired high-res MCS datasets collected offshore San Diego County. Combining these high and intermediate resolution datasets with very high resolution CHIRP data, we define structures that show distinct changes in the style of deformation through time, and place constraints on the segmentation of faults in this system. The timing of the most recent deformation on the NI/RC appears to vary along-strike. Likewise, the NI/RC fault's dip direction and angle appears to vary along-strike, and these changes in dip seem to mark the boundaries of restraining and releasing bends. Additionally, the NI/RC fault appears to die away to the north, possibly partitioning its strain on to the PV fault. We will present interpretations of the faults' current deformational activity as well as likelihood of rupture propagating across releasing/restraining bends, and discuss how this impacts current fault models that are employed for hazard assessment for Los Angeles and San Diego counties.

  14. Solving fault diagnosis problems linear synthesis techniques

    CERN Document Server

    Varga, Andreas

    2017-01-01

    This book addresses fault detection and isolation topics from a computational perspective. Unlike most existing literature, it bridges the gap between the existing well-developed theoretical results and the realm of reliable computational synthesis procedures. The model-based approach to fault detection and diagnosis has been the subject of ongoing research for the past few decades. While the theoretical aspects of fault diagnosis on the basis of linear models are well understood, most of the computational methods proposed for the synthesis of fault detection and isolation filters are not satisfactory from a numerical standpoint. Several features make this book unique in the fault detection literature: Solution of standard synthesis problems in the most general setting, for both continuous- and discrete-time systems, regardless of whether they are proper or not; consequently, the proposed synthesis procedures can solve a specific problem whenever a solution exists Emphasis on the best numerical algorithms to ...

  15. Machine Fault Signature Analysis

    Directory of Open Access Journals (Sweden)

    Pratesh Jayaswal

    2008-01-01

    Full Text Available The objective of this paper is to present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis. The different types of faults that can be identified from the vibration signature analysis are, for example, gear fault, rolling contact bearing fault, journal bearing fault, flexible coupling faults, and electrical machine fault. It is not the intention of the authors to attempt to provide a detailed coverage of all the faults while detailed consideration is given to the subject of the rolling element bearing fault signature analysis.

  16. Estimates of stress changes from the 2010 Maule, Chile earthquake: the influence on crustal faults and volcanos

    Science.gov (United States)

    Keiding, M.; Heidbach, O.; Moreno, M.; Baez, J. C.; Melnick, D.; Kukowski, N.

    2012-04-01

    The south-central Chile margin is an active plate boundary where the accumulated stress in the subduction interface is released frequently by megathrust earthquakes (Mw>8.5). The Maule earthquake of February 27 2010 affected about 500 km of the plate boundary producing spectacular tectonic deformation and a devastating tsunami. A compilation of pre-, co-, and post-earthquake geologic and geodetic data offers the opportunity of gain insight into the processes that control strain accumulation and stress changes associated to megathrust events. The fore-arc deformation is primarily controlled by the stresses that are transferred through the locked parts of the plate interface and the release of stresses during megathrust events. During a great interplate faulting event, upper plate faults, rooted in the plate interface, can play a key role in controlling fluid pressurization. Hence, the hydraulic behavior of splay faults may induce variations of shear strength and may promote dynamic slip weakening along a crustal fault. Furthermore, the co-seismic stress transfer from megathrust earthquakes can severely affect nearby volcanos promoting eruptions and local deformation. InSAR and time-series of continuous GPS in the aftermath of the Maule earthquake show evidences of activation of the NW-striking Lanalhue fault system as well as pressure increase at the Antuco volcano. We build a 3D geomechanical-numerical model that consists of 1.8 million finite elements and incorporates realistic geometries adapted from geophysical data sets as well as the major crustal faults in the region. An updated co-seismic slip model is obtained based on a joint inversion of InSAR and GPS data. The model is used to compute stress changes in the upper plate in order to investigate how the Maule earthquake may have affected the crustal faults and volcanoes in the region.

  17. 14 CFR 29.631 - Bird strike.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bird strike. 29.631 Section 29.631... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.631 Bird strike. The... safe landing (for Category B) after impact with a 2.2-lb (1.0 kg) bird when the velocity of the...

  18. Optimal fault signal estimation

    NARCIS (Netherlands)

    Stoorvogel, Antonie Arij; Niemann, H.H.; Saberi, A.; Sannuti, P.

    2002-01-01

    We consider here both fault identification and fault signal estimation. Regarding fault identification, we seek either exact or almost fault identification. On the other hand, regarding fault signal estimation, we seek either $H_2$ optimal, $H_2$ suboptimal or Hinfinity suboptimal estimation. By

  19. Fault Zone Architecture and Mineralogy: Implications in Fluid Flow and Permeability in Crustal Scale Fault Zones in the Southern Andes.

    Science.gov (United States)

    Roquer, T.; Terrón, E.; Perez-Flores, P.; Arancibia, G.; Cembrano, J. M.

    2014-12-01

    Fluid flow in the upper crust is controlled by the permeability and interconnection of fractures in the fault zones. The permeability within the fault zone is determined by its activity, architecture and, in particular, by the mineralogy of the core and the damage zone. Whereas the permeability structure of a fault zone can be defined by the volume proportion of the core with respect to the damage zone, the relationship between the mineralogy and permeability along fault zones still remains obscure. This work examines structural and mineralogical data to show the relationship between the mineral composition of the fault zone with its permeability in the Liquiñe-Ofqui Fault System (LOFS) and the Arc-oblique Long-lived Fault Systems (ALFS), Southern Chile. The LOFS is an active ca. 1200 km long strike-slip Cenozoic intra-arc structure that strikes NNE in its master traces and NE in its subsidiary traces, with dextral and dextral-normal movement mostly developed in the last 6 My. Although the LOFS and the ALFS cross-cut each other, the ALFS is an apparently older basement fault system where seismic and field evidences record sinistral, sinistral-normal and sinistral-reverse movements. One 22-m-long NE transect was mapped orthogonal to a segment of the ALFS, where host rocks are Miocene andesitic rocks. Structural and XRD sampling were conducted in the core and damage zone. Structural mapping shows a multiple core, NW-striking fault zone with foliated gouge and an asymmetric damage zone, where the hanging wall has significantly higher mesoscopic fracture density than the footwall. The hanging wall is characterized by NW-striking, steeply dipping veins. Preliminary XRD results indicate the presence of homogenously distributed Ca-rich zeolite (mainly laumontite) in the core and the veins of the damage zone, which could indicate that the core acted as a conduit for low-temperature (ca. 220°C) fluids.

  20. Modeling of periodic great earthquakes on the San Andreas fault: Effects of nonlinear crustal rheology

    Science.gov (United States)

    Reches, Ze'ev; Schubert, Gerald; Anderson, Charles

    1994-01-01

    We analyze the cycle of great earthquakes along the San Andreas fault with a finite element numerical model of deformation in a crust with a nonlinear viscoelastic rheology. The viscous component of deformation has an effective viscosity that depends exponentially on the inverse absolute temperature and nonlinearity on the shear stress; the elastic deformation is linear. Crustal thickness and temperature are constrained by seismic and heat flow data for California. The models are for anti plane strain in a 25-km-thick crustal layer having a very long, vertical strike-slip fault; the crustal block extends 250 km to either side of the fault. During the earthquake cycle that lasts 160 years, a constant plate velocity v(sub p)/2 = 17.5 mm yr is applied to the base of the crust and to the vertical end of the crustal block 250 km away from the fault. The upper half of the fault is locked during the interseismic period, while its lower half slips at the constant plate velocity. The locked part of the fault is moved abruptly 2.8 m every 160 years to simulate great earthquakes. The results are sensitive to crustal rheology. Models with quartzite-like rheology display profound transient stages in the velocity, displacement, and stress fields. The predicted transient zone extends about 3-4 times the crustal thickness on each side of the fault, significantly wider than the zone of deformation in elastic models. Models with diabase-like rheology behave similarly to elastic models and exhibit no transient stages. The model predictions are compared with geodetic observations of fault-parallel velocities in northern and central California and local rates of shear strain along the San Andreas fault. The observations are best fit by models which are 10-100 times less viscous than a quartzite-like rheology. Since the lower crust in California is composed of intermediate to mafic rocks, the present result suggests that the in situ viscosity of the crustal rock is orders of magnitude

  1. Methods of evaluating segmentation characteristics and segmentation of major faults

    International Nuclear Information System (INIS)

    Lee, Kie Hwa; Chang, Tae Woo; Kyung, Jai Bok

    2000-03-01

    Seismological, geological, and geophysical studies were made for reasonable segmentation of the Ulsan fault and the results are as follows. One- and two- dimensional electrical surveys revealed clearly the fault fracture zone enlarges systematically northward and southward from the vicinity of Mohwa-ri, indicating Mohwa-ri is at the seismic segment boundary. Field Geological survey and microscope observation of fault gouge indicates that the Quaternary faults in the area are reactivated products of the preexisting faults. Trench survey of the Chonbuk fault Galgok-ri revealed thrust faults and cumulative vertical displacement due to faulting during the late Quaternary with about 1.1-1.9 m displacement per event; the latest event occurred from 14000 to 25000 yrs. BP. The seismic survey showed the basement surface os cut by numerous reverse faults and indicated the possibility that the boundary between Kyeongsangbukdo and Kyeongsannamdo may be segment boundary

  2. Methods of evaluating segmentation characteristics and segmentation of major faults

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kie Hwa; Chang, Tae Woo; Kyung, Jai Bok [Seoul National Univ., Seoul (Korea, Republic of)] (and others)

    2000-03-15

    Seismological, geological, and geophysical studies were made for reasonable segmentation of the Ulsan fault and the results are as follows. One- and two- dimensional electrical surveys revealed clearly the fault fracture zone enlarges systematically northward and southward from the vicinity of Mohwa-ri, indicating Mohwa-ri is at the seismic segment boundary. Field Geological survey and microscope observation of fault gouge indicates that the Quaternary faults in the area are reactivated products of the preexisting faults. Trench survey of the Chonbuk fault Galgok-ri revealed thrust faults and cumulative vertical displacement due to faulting during the late Quaternary with about 1.1-1.9 m displacement per event; the latest event occurred from 14000 to 25000 yrs. BP. The seismic survey showed the basement surface os cut by numerous reverse faults and indicated the possibility that the boundary between Kyeongsangbukdo and Kyeongsannamdo may be segment boundary.

  3. Repeated fault rupture recorded by paleoenvironmental changes in a wetland sedimentary sequence ponded against the Alpine Fault, New Zealand

    Science.gov (United States)

    Clark, K.; Berryman, K. R.; Cochran, U. A.; Bartholomew, T.; Turner, G. M.

    2010-12-01

    At Hokuri Creek, in south Westland, New Zealand, an 18 m thickness of Holocene sediments has accumulated against the upthrown side of the Alpine Fault. Recent fluvial incision has created numerous exposures of this sedimentary sequence. At a decimetre to metre scale there are two dominant types of sedimentary units: clastic-dominated, grey silt packages, and organic-dominated, light brown peaty-silt units. These units represent repeated alternations of the paleoenvironment due to fault rupture over the past 7000 years. We have located the event horizons within the sedimentary sequence, and identified evidence to support earthquake-driven paleoenvironmental change (rather than climatic variability), and developed a model of paleoenvironmental changes over a typical seismic cycle. To quantitatively characterise the sediments we use high resolution photography, x-ray imaging, magnetic-susceptibility and total carbon analysis. To understand the depositional environment we used diatom and pollen studies. The organic-rich units have very low magnetic susceptibility and density values, with high greyscale and high total carbon values. Diatoms indicate these units represent stable wetland environments with standing water and predominantly in-situ organic material deposition. The clastic-rich units are characterised by higher magnetic susceptibility and density values, with low greyscale and total carbon. The clastic-rich units represent environments of flowing water and deep pond settings that received predominantly catchment-derived silt and sand. The event horizon is located at the upper contact of the organic-rich horizons. The event horizon contact marks a drastic change in hydrologic regime as fault rupture changed the stream base level and there was a synchronous influx of clastic sediment as the catchment responded to earthquake shaking. During the interseismic period the flowing-water environment gradually stabilised and returned to an organic-rich wetland. Such

  4. Numerical simulation of the 1976 Ms7.8 Tangshan Earthquake

    Science.gov (United States)

    Li, Zhengbo; Chen, Xiaofei

    2017-04-01

    An Ms 7.8 earthquake happened in Tangshan in 1976, causing more than 240000 people death and almost destroying the whole city. Numerous studies indicated that the surface rupture zone extends 8 to 11 km in the south of Tangshan City. The fault system is composed with more than ten NE-trending right-lateral strike-slip left-stepping echelon faults, with a general strike direction of N30°E. However, recent scholars proposed that the surface ruptures appeared in a larger area. To simulate the rupture process closer to the real situation, the curvilinear grid finite difference method presented by Zhang et al. (2006, 2014) which can handle the free surface and the complex geometry were implemented to investigate the dynamic rupture and ground motion of Tangshan earthquake. With the data from field survey, seismic section, borehole and trenching results given by different studies, several fault geometry models were established. The intensity, the seismic waveform and the displacement resulted from the simulation of different models were compared with the observed data. The comparison of these models shows details of the rupture process of the Tangshan earthquake and implies super-shear may occur during the rupture, which is important for better understanding of this complicated rupture process and seismic hazard distributions of this earthquake.

  5. Structural analysis of cataclastic rock of active fault damage zones: An example from Nojima and Arima-Takatsuki fault zones (SW Japan)

    Science.gov (United States)

    Satsukawa, T.; Lin, A.

    2016-12-01

    Most of the large intraplate earthquakes which occur as slip on mature active faults induce serious damages, in spite of their relatively small magnitudes comparing to subduction-zone earthquakes. After 1995 Kobe Mw7.2 earthquake, a number of studies have been done to understand the structure, physical properties and dynamic phenomenon of active faults. However, the deformation mechanics and related earthquake generating mechanism in the intraplate active fault zone are still poorly understood. The detailed, multi-scalar structural analysis of faults and of fault rocks has to be the starting point for reconstructing the complex framework of brittle deformation. Here, we present two examples of active fault damage zones: Nojima fault and Arima-Takatsuki active fault zone in the southwest Japan. We perform field investigations, combined with meso-and micro-structural analyses of fault-related rocks, which provide the important information in reconstructing the long-term seismic faulting behavior and tectonic environment. Our study shows that in both sites, damage zone is observed in over 10m, which is composed by the host rocks, foliated and non-foliated cataclasites, fault gouge and fault breccia. The slickenside striations in Asano fault, the splay fault of Nojima fault, indicate a dextral movement sense with some normal components. Whereas, those of Arima-Takatsuki active fault shows a dextral strike-slip fault with minor vertical component. Fault gouges consist of brown-gray matrix of fine grains and composed by several layers from few millimeters to a few decimeters. It implies that slip is repeated during millions of years, as the high concentration and physical interconnectivity of fine-grained minerals in brittle fault rocks produce the fault's intrinsic weakness in the crust. Therefore, faults rarely express only on single, discrete deformation episode, but are the cumulative result of several superimposed slip events.

  6. Fault Severity Evaluation and Improvement Design for Mechanical Systems Using the Fault Injection Technique and Gini Concordance Measure

    Directory of Open Access Journals (Sweden)

    Jianing Wu

    2014-01-01

    Full Text Available A new fault injection and Gini concordance based method has been developed for fault severity analysis for multibody mechanical systems concerning their dynamic properties. The fault tree analysis (FTA is employed to roughly identify the faults needed to be considered. According to constitution of the mechanical system, the dynamic properties can be achieved by solving the equations that include many types of faults which are injected by using the fault injection technique. Then, the Gini concordance is used to measure the correspondence between the performance with faults and under normal operation thereby providing useful hints of severity ranking in subsystems for reliability design. One numerical example and a series of experiments are provided to illustrate the application of the new method. The results indicate that the proposed method can accurately model the faults and receive the correct information of fault severity. Some strategies are also proposed for reliability improvement of the spacecraft solar array.

  7. Fault zone structure from topography: signatures of en echelon fault slip at Mustang Ridge on the San Andreas Fault, Monterey County, California

    Science.gov (United States)

    DeLong, Stephen B.; Hilley, George E.; Rymer, Michael J.; Prentice, Carol

    2010-01-01

    We used high-resolution topography to quantify the spatial distribution of scarps, linear valleys, topographic sinks, and oversteepened stream channels formed along an extensional step over on the San Andreas Fault (SAF) at Mustang Ridge, California. This location provides detail of both creeping fault landform development and complex fault zone kinematics. Here, the SAF creeps 10–14 mm/yr slower than at locations ∼20 km along the fault in either direction. This spatial change in creep rate is coincident with a series of en echelon oblique-normal faults that strike obliquely to the SAF and may accommodate the missing deformation. This study presents a suite of analyses that are helpful for proper mapping of faults in locations where high-resolution topographic data are available. Furthermore, our analyses indicate that two large subsidiary faults near the center of the step over zone appear to carry significant distributed deformation based on their large apparent vertical offsets, the presence of associated sag ponds and fluvial knickpoints, and the observation that they are rotating a segment of the main SAF. Several subsidiary faults in the southeastern portion of Mustang Ridge are likely less active; they have few associated sag ponds and have older scarp morphologic ages and subdued channel knickpoints. Several faults in the northwestern part of Mustang Ridge, though relatively small, are likely also actively accommodating active fault slip based on their young morphologic ages and the presence of associated sag ponds.

  8. Recent geodynamics of major strike-slip zones

    Directory of Open Access Journals (Sweden)

    Vladimir G. Trifonov

    2015-09-01

    In all of the cases mentioned above, strike-slip deformation was expressed only or mainly during strong earthquakes. At other times, the rate of its accumulation was small and the dominant stress conditions led to transverse shortening, rarely resulting in local lengthening of the tectonic zone. These variations are caused by the tectonic peculiarities of these zones. The sinistral component of the deformation is related to the shift of the Arabian Plate relative to the African one, but also the transverse component is related to the continental slope and is expressed by the Coastal range shortening that exists in the El Ghab segment zone. There is not only a dextral deformation component, but also a transverse component, expressed by shortening of the Fergana and Talas ranges existing in the Talas-Fergana fault zone. In both zones, the shortening component became appreciable or dominant when the strike-slip deformation rate decreased. Similar, but more local, relationships were expressed in the epicentral area of the 2003 Altai earthquake and in the Western Palmyrides.

  9. 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.

  10. Slip patterns and earthquake populations along different classes of faults in elastic solids

    Science.gov (United States)

    Ben-Zion, Yehuda; Rice, James R.

    1995-07-01

    Numerical simulations of slip instabilities on a vertical strike-slip fault in an elastic half-space are performed for various models belonging to two different categories. The first category consists of inherently discrete cellular fault models. Such are used to represent fault systems made of segments (modeled by numerical cells) that can fail independently of one another. Their quasi-independence is assumed to provide an approximate representation of strong fault heterogeneity, due to geometric or material property disorder, that can arrest ruptures at segment boundaries. The second category consists of models having a well-defined continuum limit. These involve a fault governed by rate- and state-dependent friction and are used to evaluate what types of property heterogeneity could lead to the quasi-independent behavior of neighboring fault segments assumed in the first category. The cases examined include models of a cellular fault subjected to various complex spatial distributions of static to kinetic strength drops, and models incorporating rate- and state-dependent friction subjected to various spatial distributions of effective stress (normal stress minus pore pressure). The results indicate that gradual effective stress variations do not provide a sufficient mechanism for the generation of observed seismic response. Strong and abrupt fault heterogeneity, as envisioned in the inherently discrete category, is required for the generation of complex slip patterns and a wide spectrum of event sizes. Strong fault heterogeneity also facilitates the generation of rough rupture fronts capable of radiating high-frequency seismic waves. The large earthquakes in both categories of models occur on a quasi-periodic basis; the degree of periodicity increases with event size and decreases with model complexity. However, in all discrete segmented cases the models generate nonrepeating sequences of earthquakes, and the nature of the large (quasi-periodic) events is highly

  11. From tomographic images to fault heterogeneities

    Directory of Open Access Journals (Sweden)

    A. Amato

    1994-06-01

    Full Text Available Local Earthquake Tomography (LET is a useful tool for imaging lateral heterogeneities in the upper crust. The pattern of P- and S-wave velocity anomalies, in relation to the seismicity distribution along active fault zones. can shed light on the existence of discrete seismogenic patches. Recent tomographic studies in well monitored seismic areas have shown that the regions with large seismic moment release generally correspond to high velocity zones (HVZ's. In this paper, we discuss the relationship between the seismogenic behavior of faults and the velocity structure of fault zones as inferred from seismic tomography. First, we review some recent tomographic studies in active strike-slip faults. We show examples from different segments of the San Andreas fault system (Parkfield, Loma Prieta, where detailed studies have been carried out in recent years. We also show two applications of LET to thrust faults (Coalinga, Friuli. Then, we focus on the Irpinia normal fault zone (South-Central Italy, where a Ms = 6.9 earthquake occurred in 1980 and many thousands of attershock travel time data are available. We find that earthquake hypocenters concentrate in HVZ's, whereas low velocity zones (LVZ’ s appear to be relatively aseismic. The main HVZ's along which the mainshock rupture bas propagated may correspond to velocity weakening fault regions, whereas the LVZ's are probably related to weak materials undergoing stable slip (velocity strengthening. A correlation exists between this HVZ and the area with larger coseismic slip along the fault, according to both surface evidence (a fault scarp as high as 1 m and strong ground motion waveform modeling. Smaller wave-length, low-velocity anomalies detected along the fault may be the expression of velocity strengthening sections, where aseismic slip occurs. According to our results, the rupture at the nucleation depth (~ 10-12 km is continuous for the whole fault lenoth (~ 30 km, whereas at shallow depth

  12. 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.

  13. NEO-TECTONIC FEATURES OF THE YAZIR FAULT (KONYA

    Directory of Open Access Journals (Sweden)

    Yaşar EREN

    2003-02-01

    Full Text Available The Yazır fault, located to the east of the Konya fault zone bordering west side of the Konya basin, is approximately 10 km in length and is formed by en echelon groupings of the sub-parallel fault sets. NNE-SSW trending Yazır fault cuts the Miocene-Pleistocene aged lacustrine rocks and Quaternary alluvial deposits of Konya basin. In the quarries opened between the Parsana and Yazır districts, the fault brought the lacustrine and Quaternary alluvial deposits side by side. Due to faulting, the lacustrine rocks were moved upwards relative to the alluvial deposits. The Yazır and Çiftlikbaşı faults formed a small triangular shaped graben structure in the area. Between the Parsana and Yazır districts, the fault surface is nearly vertical, and has NNE-SSW orientatiton. Although the slickenlines indicate that the fault has a small right hand strike slip movement, the fault mainly is a high angle east dipping normal fault. Surface data demonstrates that, due to this faulting, at least 25-30 m of vertical displacement was taken place in the area. Depending on the movements of the Yazır fault, two extensional sets of filled fissures were formed, one set is paralel to the main fault plane the other set erpendicular. These fissures are filled by alluvial deposits, and are triangular in shape closing downward. Their width range from 15 cm to 2 m, and their length reach up to 10 m, in vertical plane. The fissures have N10E, 90 and N80 W, 85 SW main orientation. Field observations indicate that these filled fissures were formed as surface cracks during movements of the Yazır fault at least twice. The orientations of these extensional cracks show that this part of the Konya plain was affected by east-west and north-south horizontally oriented tensional stresses.

  14. Extremely Shallow Extensional Faulting Near Geothermal Fields

    Science.gov (United States)

    Hudnut, K. W.; Wei, S.; Donnellan, A.; Fielding, E. J.; Graves, R. W.; Helmberger, D. V.; Liu, Z.; Parker, J. W.; Treiman, J. A.

    2013-12-01

    Surface faulting has been discovered in association with a shallow extensional M 4.9 earthquake, the source properties of which have also been studied by modeling of broadband seismic data and geodetic imagery. This M 4.9 and also a M 4.6 shallow normal event occurred late in the Brawley Swarm of August 2012, a dominantly strike-slip sequence with events up to M 5.5 (Hauksson et al., SRL 2013 and Wei et al., GRL 2013). The point source waveform inversions reveal normal mechanisms and centroid depths of ~2.5 km for both events, while the modeling of the geodetic data indicates a compatible depth of ~2.0 km. The M 4.9 event had unusually large (~40 cm) and sudden (~1.0 - 1.5 km/sec) slip, considering its extremely shallow depth. The earlier and larger strike-slip events during the Aug. 2012 swarm were on a left-lateral SW-NE oriented vertical planar cross-fault, whereas the M 4.6 and M 4.9 occurred on a SSW-NNE oriented, west-dipping plane. Airborne imagery obtained using Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) revealed a surface fault rupture that was subsequently confirmed and documented in the field in May 2013. A pre-existing but previously un-mapped fault sustained west-down surface slip of up to 18 × 2 cm along breaks extending ~3.5 km along a NNE orientation, and ruptured beneath and under a railroad track and pipeline (without breaking them). UAVSAR and seismological data were used jointly to image the source properties of the M 4.9 earthquake in detail. Typically, the uppermost few kms of right-lateral faults in the Salton Trough exhibit creep, especially after larger earthquakes, as in 1979 and 1987. On this basis, general models of stable sliding within the uppermost few kms have been developed. In this case, however, the joint inversion indicates that seismic energy was radiated by slip of up to 40 cm on a fault plane extending from the surface to a depth of only ~3 km, extending ~4 km along-strike, and dipping ~45° west, with west

  15. Fault detection and isolation in systems with parametric faults

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, Hans Henrik

    1999-01-01

    The problem of fault detection and isolation of parametric faults is considered in this paper. A fault detection problem based on parametric faults are associated with internal parameter variations in the dynamical system. A fault detection and isolation method for parametric faults is formulated...... in a standard setup and a synthesis method for fault detectors is given. Further, fault detection problems with both parametric faults and faults described by external input signals are also shortly considered....

  16. Fault zone fabric and fault weakness

    NARCIS (Netherlands)

    Collettini, C.; Niemeijer, A.; Viti, C.; Marone, C.

    2009-01-01

    Geological and geophysical evidence suggests that some crustal faults are weak1–6 compared to laboratory measurements of frictional strength7. Explanations for fault weakness include the presence of weak minerals4, high fluid pressures within the fault core8,9 and dynamic processes such as

  17. Influence of mineralogy and microstructures on strain localization and fault zone architecture of the Alpine Fault, New Zealand

    Science.gov (United States)

    Ichiba, T.; Kaneki, S.; Hirono, T.; Oohashi, K.; Schuck, B.; Janssen, C.; Schleicher, A.; Toy, V.; Dresen, G.

    2017-12-01

    The Alpine Fault on New Zealand's South Island is an oblique, dextral strike-slip fault that accommodated the majority of displacement between the Pacific and the Australian Plates and presents the biggest seismic hazard in the region. Along its central segment, the hanging wall comprises greenschist and amphibolite facies Alpine Schists. Exhumation from 35 km depth, along a SE-dipping detachment, lead to mylonitization which was subsequently overprinted by brittle deformation and finally resulted in the fault's 1 km wide damage zone. The geomechanical behavior of a fault is affected by the internal structure of its fault zone. Consequently, studying processes controlling fault zone architecture allows assessing the seismic hazard of a fault. Here we present the results of a combined microstructural (SEM and TEM), mineralogical (XRD) and geochemical (XRF) investigation of outcrop samples originating from several locations along the Alpine Fault, the aim of which is to evaluate the influence of mineralogical composition, alteration and pre-existing fabric on strain localization and to identify the controls on the fault zone architecture, particularly the locus of brittle deformation in P, T and t space. Field observations reveal that the fault's principal slip zone (PSZ) is either a thin (govern strain localization. However, our preliminary results suggest that qualitative mineralogical composition has only minor impact on fault zone architecture. Quantities of individual mineral phases differ markedly between fault damage zone and fault core at specific sites, but the quantitative composition of identical structural units such as the fault core, is similar in all samples. This indicates that the degree of strain localization at the Alpine Fault might be controlled by small initial heterogeneities in texture and fabric or a combination of these, rather than in mineralogy. Further microstructural investigations are needed to test this hypothesis.

  18. Expeditionary Strike Group: Command Structure Design Support

    National Research Council Canada - National Science Library

    Hutchins, Susan G; Kemple, William G; Kleinman, David L; Hocevar, Susan P

    2005-01-01

    An Expeditionary Strike Group (ESG) is a new capability mix that combines the combat power of three surface combatants and one submarine with an Amphibious Readiness Group/ Marine Expeditionary Unit...

  19. The Chicago Teachers Strike and Its Public

    Science.gov (United States)

    Shuffelton, Amy B.

    2014-01-01

    This article considers the 2012 Chicago Teachers Strike in light of John Dewey's "The Public and Its Problems." It engages Dewey's conceptualization of practical reason to challenge the educational reform movement's commitment to technocratic decision-making.

  20. Strikes in the public sector in Denmark

    DEFF Research Database (Denmark)

    Scheuer, Steen; Ibsen, Flemming; Høgedahl, Laust

    2016-01-01

    This article looks at strikes by employees in the public sector, discusses the theoretical background to these conflicts and shows – based on a case study of three strikes in the Danish public sector – how different union strategies lead to very different outcomes in terms of economic gains......, while public sector unions trying to move up the wage hierarchy cannot expect much help from fellow public sector unions, often quite the reverse....

  1. Stress field of a dislocating inclined fault

    Energy Technology Data Exchange (ETDEWEB)

    Huang, F.; Wang, T.

    1980-02-01

    Analytical expressions are derived for the stress field caused by a rectangular dislocating fault of an arbitrary dip in a semi-infinite elastic medium for the case of unequal Lame constants. The results of computations for the stress fields on the ground surface of an inclined strike-slip and an inclined dip-slip fault are represented by contour maps. The effects of Poisson Ratio of the medium, the dip angle, upper and lower boundaries of the faults on the stress field at surface have been discussed. As an application, the contour maps for shear stress and hydrostatic stress of near fields of the Tonghai (1970), Haicheng (1975) and Tangshan (1976) earthquakes have been calculated and compared with the spatial distributions of strong aftershocks of these earthquakes. It is found that most of the strong aftershocks are distributed in the regions of tensional stress, where the hydrostatic stress is positive.

  2. Stress field of a dislocating inclined fault

    Energy Technology Data Exchange (ETDEWEB)

    Huang, F.; Wang, T.

    1980-02-01

    In this paper, analytical expressions of the stress field given rise by a rectangular dislocating fault of an arbitrary dip in a semi-infinite elastic medium for the case of unequal Lame constants are derived. The results of computations for the stress fields on the ground surface of an inclined strike-slip and an inclined dip-slip fault are represented by contour maps. The effects of the Poisson Ratio of the medium, the dip angle, upper and lower boundaries of the faults on the stress field at the surface have been discussed. As an application, the contour maps for shear stress and hydrostatic stress of near fields of the Tonghai (1970), Haicheng, (1975) and Tangshan (1976) earthquakes have been calculated and compared with the spatial distributions of strong aftershocks of these earthquakes. It is found that most of the strong aftershocks are distributed in the regions of tensional stress where the hydrostatic stress is positive.

  3. Quaternary geology and neotectonic activity along the Fish Lake Valley Fault Zone, Nevada and California

    International Nuclear Information System (INIS)

    Sawyer, T.L.

    1990-08-01

    The right-divergent Fish Lake Valley fault zone (FLVFZ), a 80 KM-long component of the northern Death Valley fault system, comprises contemporaneous NW-striking dextral faults, N-striking normal faults, NE-striking left(?)-divergent faults, and locally WNW-striking contractional faults. The fault zone terminates in a horsetail splay where the minimum right-slip rate is 0.7--0.8 mm/yr. The styles and rates of faulting are based on a sequence of morphostratigraphic units disrupted by the FLVFZ. Geomorphic surface correlations, radiocarbon analyses, tephrochronology, and soil development studies were used to estimate unit ages. Paleoseismicity studies have identified three discrete slip events in the last 4 to 2 ka on the northern FLVFZ. The last two significant events were similar, suggesting a characteristic earthquake behavior and magnitudes of 7.1 ± 0.3. The last large event occurred 1 ka (±0.6, -0.5) and comparable events have repeated every 1.1 Ka (+2.3, -0.5). Source structure characteristics suggest a MCE of M 7.3 ± 0.4

  4. Paleoseismology and tectonic geomorphology of the Pallatanga fault (Central Ecuador), a major structure of the South-American crust

    Science.gov (United States)

    Baize, Stéphane; Audin, Laurence; Winter, Thierry; Alvarado, Alexandra; Pilatasig Moreno, Luis; Taipe, Mercedes; Reyes, Pedro; Kauffmann, Paul; Yepes, Hugo

    2015-05-01

    The Pallatanga fault (PF) is a prominent NNE-SSW strike-slip fault crossing Central Ecuador. This structure is suspected to have hosted large earthquakes, including the 1797 Riobamba event which caused severe destructions to buildings and a heavy death toll (more than 12,000 people), as well as widespread secondary effects like landsliding, liquefaction and surface cracking. The scope of this study is to evaluate the seismic history of the fault through a paleoseismological approach. This work also aims at improving the seismotectonic map of this part of the Andes through a new mapping campaign and, finally, aims at improving the seismic hazard assessment. We show that the PF continues to the north of the previously mapped fault portion in the Western Cordillera (Rumipamba-Pallatanga portion) into the Inter-Andean Valley (Riobamba basin). Field evidences of faulting are numerous, ranging from a clear geomorphological signature to fault plane outcrops. Along the western side of the Riobamba basin, the strike-slip component seems predominant along several fault portions, with a typical landscape assemblage (dextral offsets of valleys, fluvial terrace risers and generation of linear pressure ridges). In the core of the inter-Andean valley, the main fault portion exhibits a vertical component along the c. 100 m-high cumulative scarp. The presence of such an active fault bounding the western suburbs of Riobamba drastically increases the seismic risk for this densely inhabited and vulnerable city. To the east (Peltetec Massif, Cordillera Real), the continuation of the Pallatanga fault is suspected, but not definitely proved yet. Based on the analysis of three trenches, we state that the Rumipamba-Pallatanga section of the PF experienced 4 (maybe 5) Holocene to Historical strong events (Mw > 7). The coseismic behavior of the fault is deduced from the occurrence of several colluvial wedges and layers associated with the fault activity and interbedded within the organic

  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. High Resolution Seismic Imaging of the Trench Canyon Fault Zone, Mono Lake, Northeastern California

    Science.gov (United States)

    Novick, M. W.; Jayko, A. S.; Roeske, S.; McClain, J. S.; Hart, P. E.; Boyle, M.

    2009-12-01

    High resolution seismic imaging of Mono Lake, located in northeastern California, has revealed an approximately northwest striking fault in the area to the west of aerially exposed Negit Volcano. This fault, henceforth referred to as the Trench Canyon Fault (TCF), has also been mapped onshore along a correlating strike as far north as Cedar Hill Volcano, located to the northeast of the lake on the California/Nevada border. Onshore, the TCF was mapped for approximately 10 kilometers using air photos, DEM images, and standard geologic pace and compass mapping techniques. The TCF post- dates the last glacial maximum, evidenced by the cutting of wave cut benches along Cedar Hill Volcano. Relict, non-historic shorelines, left by the steady evaporation of Mono Lake beginning approximately 13k, are also repeatedly cut by the fault. Additional evidence of fault presence includes sag ponds, pressure ridges, tectonically fractured rocks, and normal fault scarps found along strike. Offshore, DEM images show a northeast striking structure to the northwest of Negit Volcano, which is co-linear with the onshore TCF. High resolution seismic imaging of the structure, using an applied acoustic/SIG mini-sparker system, reveals steeply dipping Holocene sediments, as well as volcanic deposits from active vents which have erupted in the last 1000 years, offset by the fault. Detailed structural analysis of the previously unstudied Trench Canyon Fault (TFC) and faults in the Cedar Hill region of northern California, along with seismic studies of sediments beneath Mono Lake not only allow for a better comprehension of this minor fault system, but provide greater understanding of the larger and more complex Walker Lane Shear Zone. Fault analyses, combined and correlated with those from CHV, give a better understanding of how slip is transferred into the complicated Mina defection to the east, from the dextral and normal faults along the Sierra Nevada Range front.

  7. Four-Dimensional Transform Fault Processes: Evolution of Step-Overs and Bends at Different Scales

    Science.gov (United States)

    Wakabayashi, J.; Hengesh, J. V.; Sawyer, T. L.

    2002-12-01

    Many bends or step-overs along strike-slip faults may evolve by propagation of the strike-slip fault on one side of the structure and progressive shut off of the strike-slip fault on the other side. In such a process, new transverse structures form, old ones become inactive, and the bend or step-over region migrates with respect to materials that were once affected by it. This process is the progressive asymmetric development of a strike-slip duplex. Consequences of this type of step-over evolution include the following: 1. the amount of vertical structural relief in restraining step-over or bend regions is less than expected (apatite fission track ages associated with these step-over regions predate the strike-slip faulting); 2. pull-apart basin deposits are left outside of the active basin and commonly subjected to contractional deformation and uplift; and 3. local basin inversion occurs that is not linked to regional plate motion changes. This type of evolution of step-overs and bends may be common along the dextral San Andreas fault system of California. Examples of pull-apart basin deposits related to migrating releasing () bends or step-overs are the Plio-Pleistocene Merced Formation (tens of km along strike), the Pleistocene Olema Creek Formation (several km along strike) along the San Andreas fault in the San Francisco Bay area, and an inverted colluvial graben exposed in a paleoseismic trench across the Miller Creek fault (meters to tens of meters along strike) in the eastern San Francisco Bay area. Examples of migrating restraining bends or step-overs include the transfer of slip from the Calaveras to Hayward fault in the Mission Peak area, and the Greenville to the Concord fault at Mount Diablo (10 km or more along strike), the offshore San Gregorio fold and thrust belt (40 km along strike), and the progressive transfer of slip from the eastern faults of the San Andreas system to the migrating Mendocino triple junction (over 150 km along strike). Another

  8. Probabilistic Risk Assessment: Piping Fragility due to Earthquake Fault Mechanisms

    Directory of Open Access Journals (Sweden)

    Bu Seog Ju

    2015-01-01

    Full Text Available A lifeline system, serving as an energy-supply system, is an essential component of urban infrastructure. In a hospital, for example, the piping system supplies elements essential for hospital operations, such as water and fire-suppression foam. Such nonstructural components, especially piping systems and their subcomponents, must remain operational and functional during earthquake-induced fires. But the behavior of piping systems as subjected to seismic ground motions is very complex, owing particularly to the nonlinearity affected by the existence of many connections such as T-joints and elbows. The present study carried out a probabilistic risk assessment on a hospital fire-protection piping system’s acceleration-sensitive 2-inch T-joint sprinkler components under seismic ground motions. Specifically, the system’s seismic capacity, using an experimental-test-based nonlinear finite element (FE model, was evaluated for the probability of failure under different earthquake-fault mechanisms including normal fault, reverse fault, strike-slip fault, and near-source ground motions. It was observed that the probabilistic failure of the T-joint of the fire-protection piping system varied significantly according to the fault mechanisms. The normal-fault mechanism led to a higher probability of system failure at locations 1 and 2. The strike-slip fault mechanism, contrastingly, affected the lowest fragility of the piping system at a higher PGA.

  9. Four-dimensional transform fault processes: progressive evolution of step-overs and bends

    Science.gov (United States)

    Wakabayashi, John; Hengesh, James V.; Sawyer, Thomas L.

    2004-11-01

    Many bends or step-overs along strike-slip faults may evolve by propagation of the strike-slip fault on one side of the structure and progressive shut-off of the strike-slip fault on the other side. In such a process, new transverse structures form, and the bend or step-over region migrates with respect to materials that were once affected by it. This process is the progressive asymmetric development of a strike-slip duplex. Consequences of this type of step-over evolution include: (1) the amount of structural relief in the restraining step-over or bend region is less than expected; (2) pull-apart basin deposits are left outside of the active basin; and (3) local tectonic inversion occurs that is not linked to regional plate boundary kinematic changes. This type of evolution of step-overs and bends may be common along the dextral San Andreas fault system of California; we present evidence at different scales for the evolution of bends and step-overs along this fault system. Examples of pull-apart basin deposits related to migrating releasing (right) bends or step-overs are the Plio-Pleistocene Merced Formation (tens of km along strike), the Pleistocene Olema Creek Formation (several km along strike) along the San Andreas fault in the San Francisco Bay area, and an inverted colluvial graben exposed in a paleoseismic trench across the Miller Creek fault (meters to tens of meters along strike) in the eastern San Francisco Bay area. Examples of migrating restraining bends or step-overs include the transfer of slip from the Calaveras to Hayward fault, and the Greenville to the Concord fault (ten km or more along strike), the offshore San Gregorio fold and thrust belt (40 km along strike), and the progressive transfer of slip from the eastern faults of the San Andreas system to the migrating Mendocino triple junction (over 150 km along strike). Similar 4D evolution may characterize the evolution of other regions in the world, including the Dead Sea pull-apart, the Gulf

  10. 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

  11. Comparing Numerical and Analog Models of Oblique Convergence With Nature

    Science.gov (United States)

    Koster, K.; Haq, S. S.; Flesch, L. M.

    2011-12-01

    Relative plate motion at convergent plate boundaries is rarely perfectly margin-normal, instead it typically exhibits some obliquity to the overlying plate. The resulting margin-parallel component of plate motion can have a considerable influence in determining the distribution and style of large-scale deformation at the margin. In accretionary prisms and fold and thrust belts oblique plate motion and the resulting deformation frequently results in spatially segregated dip-slip and strike-slip faulting in the deforming wedge. Analog modeling has demonstrated that the type of shearing structures that occur in response to this motion is strongly correlated with the vertical variation in rheology, where ductile layers at depth will localize strike-slip deformation. Additionally, we have performed numerical simulations where we solve force-balance equations for Stokes flow for oblique wedges with similar geometries and rheologies using the finite element software COMSOL. Using frictional and layered, frictional over viscous, rheologies we further constrain the role that rheological complexity plays in determining the style and distribution of deformation and of stress. In our numerical models, we have simulated a range of obliquities as well as layered rheologies to determine internal stresses in actively deforming wedges. Results from our numerical experiments are in agreement with available kinematic data from comparable analog experiments, suggesting our numerical method is also viable and suitable for modeling natural settings. Numerical models that simulated frictional wedges were characterized by diffusely distributed shear throughout the pro-wedge at low obliquities, and weakly partitioned strain, similar to analog results. However, the localization of shear in rheologically complex numerical models occurred across a narrower zone at comparable obliquities in both numerical and analog results, corresponding to the location where there the transition in basal

  12. Local Stress fields and paleo-fluid distribution within a transtensional duplex: An example from the northern termination of the Liquiñe-Ofqui Fault System.

    Science.gov (United States)

    Perez-Flores, P.; Cembrano, J. M.; Sanchez-Alfaro, P.

    2014-12-01

    The northern termination of Liquiñe-Ofqui Fault System (LOFS) is characterized by major NNE-striking dextral strike-slip faults and several second and third-order NE-to-ENE-striking oblique-slip faults. This geometry forms a transtensional duplex structure. The LOFS has a complex crosscutting relationship with inherited NW-striking structures of the Arc-oblique long-lived Fault System (ALFS). We conducted a structural mapping of fault and vein populations at key structural sites representative of each regional structural system. Field observations were combined with different methods of inversion of fault-slip heterogeneous data and with the use of different open-source computer programs that calculate resolved stress tensors and P-T axes for each structural site in order to unravel the significance of this complex architecture. The results of the inversion of fault-slip analysis show that a transtensional strike-slip regime, with NE-SW-trending subhorizontal σ1, predominate in the first and second order faults in the northern termination of the duplex. A more local tensional regime was calculated for the same area. The inversion solutions are compatible with NE-trending subvertical veins system and dilational jogs and breccia. In contrast, within the central area of the duplex fault slip inversion of fault populations shows both transpressional and compressional regimes. The first tectonic regime is compatible with ENE-striking veins and dikes. In the southern part of the duplex, fault populations are compatible with either a local transtensional stress field with an ESE-trending subhorizontal σ1 or with a tensional regime with a SW-trending, steeply plunging σ1. Our results show the complexity in the nature and spatial distribution of stress fields within strike-slip duplexes and its role in the geometrical distribution of paleo-fluid flow, part of which may account for the reactivation of inherited faults or strain incompatibilities at fault intersections.

  13. Block Island fault: A Paleozoic crustal boundary on the Long Island platform

    Science.gov (United States)

    Hutchinson, Deborah R.; Klitgord, Kim D.; Detrick, R. S.

    1985-01-01

    A major fault cutting through most of the crust can be identified and mapped on the Long Island platform using multichannel seismic reflection profiles and magnetic data. The fault, here called the Block Island fault (BIF), strikes north-northeast, dips westward at low angle, and does not resemble the thin-skinned thrust faulting observed in the foreland of the Appalachians. The BIF is located within the hinterland of the Appalachian mountain belt in the collision zone between Africa and North America. We present several interpretations but favor one in which the fault originated as an east-verging mid–late Paleozoic thrust fault, possibly related to the collision of Avalon or Meguma with North America. It was probably reactivated during early Mesozoic continental breakup and again in the Late Cretaceous and Tertiary, causing the steeply dipping postrift New Shoreham fault to form, either as an antithetic (normal) or splay (reverse) fault.

  14. On the use of imaginary faults in palaeostress analysis

    Science.gov (United States)

    Shan, Yehua; Liang, Xinquan

    2017-11-01

    The imaginary fault refers to the counterpart of a certain given fault that has a similar expression about the Wallace-Bott hypothesis. It is included to further reduce the feasible fields for the principal stress directions using the right dihedra method. The given fault and its imaginary fault have a similar dip-slip sense under the extensional or compressional regime but, as proved in this paper, a different dip-slip sense under the strike-slip regime. Their relation in dip-slip sense does no change with the rotation of the coordinate system, thus making possible the general use in the reduction of the imaginary faults under any tectonic regime. A procedure for this use is proposed and applied to a real example to demonstrate the feasibility of this method.

  15. Core Description and Characteristics of Fault Zones from Hole-A of the Taiwan Chelungpu-Fault Drilling Project

    Directory of Open Access Journals (Sweden)

    En-Chao Yeh

    2007-01-01

    Full Text Available Taiwan Chelungpu-fault Drilling Project was conducted in drill site Dakeng, Taichung City of central western Taiwan during 2004 - 2005 principally to investigate the rupture mechanism in the northern segment of the Chi-Chi earthquake of 21 September 1999, and also to examine regional stratigraphy and tectonics. Core examination (500 - 1800 m of Hole-A gave profound results aiding in illustrating the lithologic column, deformation structure, and architectural pattern of fault zones along the borehole. Lithology column of Hole-A was identified downward as the Cholan Formation (500 - 1027 m, Chinshui Shale (1027 - 1268 m, Kueichulin Formation (1268 - 1712 m, and back to the Cholan Formation (1712 - 2003 m again. A dramatic change is observed regarding sedimentation age and deformation structure around 1712 m. Along the core, most bedding dips _ _ Around 1785 m, bedding dip jumps up to _ the bottom of borehole. Five structure groups of different orientations (dip direction/dip are observed throughout the core. Based on the orientation and sense of shear, they are categorized as thrust (105/30, left-lateral fault (015/30 - 80, right-lateral fault (195/30 - 80, normal fault (105/5 - 10, and backthrust (285/40 - 50. Ten fault zones have been recognized between 500 and 2003 m. We interpret the fault zone located at around 1111 m as being the most likely candidate for rupture deformation during Chi-Chi earthquake. The fault zone seated around 1712 m is recognized as the Sanyi fault zone which is 600 m beneath the Chelungpu fault zone. Ten fault zones including thrust faults, strike-slip faults and backthrust are classified as the Chelungpu Fault System (1500 m. According to the deformation textures within fault zones, the fault zones can be categorized as three types of deformation: distinct fracture deformation, clayey-gouge deformation, and soft-rock deformation. Fracture deformation is dominant within the Chelungpu Fault System and abother two

  16. New Insights into Old Events: Improving Estimates of the Spatial Heterogeneity and Distribution of Co-Seismic Slip with Depth for Several Large Magnitude Strike-Slip Earthquakes using Geodetic Observations of the Near-Field Deformation.

    Science.gov (United States)

    Milliner, C. W. D.; Burgmann, R.; Wang, T.

    2016-12-01

    Finite-fault inversions of geodetic data to estimate co-seismic slip at depth, provide important information for faulting mechanics, understanding the behavior of the rupture process and constraints for dynamic rupture simulations. However, incorporating measurement of the near-field surface deformation has typically been difficult, due to decorrelation of the InSAR phase caused by complex ground deformation, and the difficulty of measuring diffuse, `off-fault' deformation in geologic field surveys. Such a lack of near-field data has been found to artificially generate deficits of shallow slip, by (a) overestimating slip at larger depths (3-8 km) by up to 30% [Xu et al. 2016], and (b) limiting the size of near-surface patches, with coarser meshes found to underestimate shallow slip [Huang et al. 2015], in turn distorting the spatial variation of slip across the rupture plane. Here we will present new results of kinematic slip inversions for the 1999 Mw 7.1 Hector Mine, 1999 Mw 7.6 Izmit and 2015 Mw 7.2 Tajikistan earthquakes using GPS data, SAR interferograms with refined phase unwrapping using SNAPHU, new SAR azimuth offsets, and optical image correlation results that can provide important near-field constraints of surface motion. Improved slip distributions for these large strike-slip earthquakes, which span a range of structural maturities, will allow us to assess whether more mature, `smoother' faults exhibit smoother slip distributions as predicted by quasi-static [Dieterich and Smith, 2009] and dynamic numerical rupture simulations [Dunham et al. 2011], and whether deficits of shallow slip are robust features. Understanding whether ruptures exhibit a deficit of shallow slip, and how the spatial heterogeneity of slip may vary between different fault systems holds significance for understanding how strain is released throughout the seismic cycle, generating realistic synthetic simulations of earthquake ruptures and the expected amount of ground shaking.

  17. Aseismic strike-slip associated with the 2007 dike intrusion episode in Tanzania

    Science.gov (United States)

    Himematsu, Yuji; Furuya, Masato

    2015-08-01

    In July 2007, an earthquake swarm initiated in northern Tanzania near Lake Natron and lasted for about two months. Mt. Oldoinyo Lengai, located to the southwest of the swarm, began to erupt effusively about a month prior to the swarm, and increased its eruption intensity on September when the swarm almost ceased. Several previous studies have already reported the crustal deformation signals associated with the swarm using Interferometric Synthetic Aperture Radar (InSAR). However, nearly all the published data are based on the C-band ENVISAT/ASAR images acquired only from the descending path. We use the L-band ALOS/PALSAR images acquired from both ascending and descending paths, which allow us to examine the deformation signals in more detail. In addition to the InSAR data, we employ the offset-tracking technique to detect the signals along the azimuth direction. Using InSAR and offset-tracking data, we obtain the full 3D displacement fields associated with the episode. Besides the horizontal extension and subsidence signals due to the dike intrusion as already reported, the inferred full 3D displacements further indicate that the subsiding zone was horizontally moving by ~ 48 cm toward SSW. To explain the displacements, we performed fault source modeling, assuming an elastic half space. The fault slip distribution indicates that the contribution of the strike-slip component is about 20% of total moment release. Because almost all the focal mechanisms of earthquakes during the 2007 event indicate nearly pure normal faulting, aseismic strike-slip must have been responsible for the horizontal movement of the subsiding zone. The strike-slip at the shallowest depths suggests the presence of transtensive stress, which seems to be reasonable to generate the relay zones that are widely observed in the East African Rift. We also confirmed that the stress changes due to the dike intrusion were consistent with the inferred fault slip distributions.

  18. The Cottage Grove fault system (Illinois Basin): Late Paleozoic transpression along a Precambrian crustal boundary

    Science.gov (United States)

    Duchek, A.B.; McBride, J.H.; Nelson, W.J.; Leetaru, H.E.

    2004-01-01

    The Cottage Grove fault system in southern Illinois has long been interpreted as an intracratonic dextral strike-slip fault system. We investigated its structural geometry and kinematics in detail using (1) outcrop data, (2) extensive exposures in underground coal mines, (3) abundant borehole data, and (4) a network of industry seismic reflection profiles, including data reprocessed by us. Structural contour mapping delineates distinct monoclines, broad anticlines, and synclines that express Paleozoic-age deformation associated with strike slip along the fault system. As shown on seismic reflection profiles, prominent near-vertical faults that cut the entire Paleozoic section and basement-cover contact branch upward into outward-splaying, high-angle reverse faults. The master fault, sinuous along strike, is characterized along its length by an elongate anticline, ???3 km wide, that parallels the southern side of the master fault. These features signify that the overall kinematic regime was transpressional. Due to the absence of suitable piercing points, the amount of slip cannot be measured, but is constrained at less than 300 m near the ground surface. The Cottage Grove fault system apparently follows a Precambrian terrane boundary, as suggested by magnetic intensity data, the distribution of ultramafic igneous intrusions, and patterns of earthquake activity. The fault system was primarily active during the Alleghanian orogeny of Late Pennsylvanian and Early Permian time, when ultramatic igneous magma intruded along en echelon tensional fractures. ?? 2004 Geological Society of America.

  19. Active faults, paleoseismology, and historical fault rupture in northern Wairarapa, North Island, New Zealand

    International Nuclear Information System (INIS)

    Schermer, E.R.; Van Dissen, R.; Berryman, K.R.; Kelsey, H.M.; Cashman, S.M.

    2004-01-01

    Active faulting in the upper plate of the Hikurangi subduction zone, North Island, New Zealand, represents a significant seismic hazard that is not yet well understood. In northern Wairarapa, the geometry and kinematics of active faults, and the Quaternary and historical surface-rupture record, have not previously been studied in detail. We present the results of mapping and paleoseismicity studies on faults in the northern Wairarapa region to document the characteristics of active faults and the timing of earthquakes. We focus on evidence for surface rupture in the 1855 Wairarapa (M w 8.2) and 1934 Pahiatua (M w 7.4) earthquakes, two of New Zealand's largest historical earthquakes. The Dreyers Rock, Alfredton, Saunders Road, Waitawhiti, and Waipukaka faults form a northeast-trending, east-stepping array of faults. Detailed mapping of offset geomorphic features shows the rupture lengths vary from c. 7 to 20 km and single-event displacements range from 3 to 7 m, suggesting the faults are capable of generating M >7 earthquakes. Trenching results show that two earthquakes have occurred on the Alfredton Fault since c. 2900 cal. BP. The most recent event probably occurred during the 1855 Wairarapa earthquake as slip propagated northward from the Wairarapa Fault and across a 6 km wide step. Waipukaka Fault trenches show that at least three surface-rupturing earthquakes have occurred since 8290-7880 cal. BP. Analysis of stratigraphic and historical evidence suggests the most recent rupture occurred during the 1934 Pahiatua earthquake. Estimates of slip rates provided by these data suggest that a larger component of strike slip than previously suspected is occurring within the upper plate and that the faults accommodate a significant proportion of the dextral component of oblique subduction. Assessment of seismic hazard is difficult because the known fault scarp lengths appear too short to have accommodated the estimated single-event displacements. Faults in the region are

  20. Fault tree handbook

    International Nuclear Information System (INIS)

    Haasl, D.F.; Roberts, N.H.; Vesely, W.E.; Goldberg, F.F.

    1981-01-01

    This handbook describes a methodology for reliability analysis of complex systems such as those which comprise the engineered safety features of nuclear power generating stations. After an initial overview of the available system analysis approaches, the handbook focuses on a description of the deductive method known as fault tree analysis. The following aspects of fault tree analysis are covered: basic concepts for fault tree analysis; basic elements of a fault tree; fault tree construction; probability, statistics, and Boolean algebra for the fault tree analyst; qualitative and quantitative fault tree evaluation techniques; and computer codes for fault tree evaluation. Also discussed are several example problems illustrating the basic concepts of fault tree construction and evaluation

  1. ELMs, strike point jumps and SOL currents

    International Nuclear Information System (INIS)

    Solano, Emilia R.; Jachmich, S.; Villone, F.; Hawkes, N.; Guenther, K.; Korotkov, A.; Stamp, M.; Andrew, P.; Conboy, J.; Mattews, G.F.; Corre, Y.; Loarte, A.; Pitts, R.A.; Cenedese, A.; Kempenaars, M.; Bolzonella, T.; Rachlew, E.

    2005-01-01

    Plasma equilibria before and after ELMs in JET are investigated. ELMs could be associated with fragile equilibria and separatrix instabilities: previously closed field lines would open up, releasing plasma current and leading to the formation of a new, smaller separatrix. This model could explain experimental observations of sudden jumps and shifts in strike point positions. Novel instability mechanisms are discussed to explain the large transient jumps observed in the strike point position: positive X-point instability, due to positive toroidal current density at the X-point and diamagnetic instability, due to negative inboard toroidal current density. (author)

  2. 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.

  3. Quaternary layer anomalies around the Carlsberg Fault zone mapped with high-resolution shear-wave seismics south of Copenhagen

    DEFF Research Database (Denmark)

    Kammann, Janina; Hübscher, Christian; Nielsen, Lars

    The Carlsberg Fault zone is located in the N-S striking Höllviken Graben and traverses the city of Copenhagen. The fault zone is a NNW-SSE striking structure in direct vicinity to the transition zone of the Danish Basin and the Baltic Shield. Recent small earthquakes indicate activity in the area......, although none of the mapped earthquakes appear to have occurred on the Carlsberg Fault. We examined the fault evolution by a combination of very high resolution onshore shear-wave seismic data, one conventional onshore seismic profile and marine reflection seismic profiles. The chalk stratigraphy...... and the localization of the fault zone at depth was inferred from previous studies by other authors. We extrapolated the Jurassic and Triassic stratigraphy from the Pomeranian Bay to the area of investigation. The fault zone shows a flower structure in the Triassic as well as in Cretaceous sediments. The faulting...

  4. Northward expansion of Tibet beyond the Altyn Tagh Fault

    Science.gov (United States)

    Cunningham, D.; Zhang, J.; Yanfeng, L.; Vernon, R.

    2017-12-01

    For many tectonicists, the evolution of northern Tibet stops at the Altyn Tagh Fault (ATF). This study challenges that assumption. Structural field observations and remote sensing analysis indicate that the Sanweishan and Nanjieshan basement-cored ridges of the Archean Dunhuang Block, which interrupt the north Tibetan foreland directly north of the ATF, are bound and cut by an array of strike-slip, thrust and oblique-slip faults that have been active in the Quaternary and remain potentially active. The Sanweishan is essentially a SE-tilted block that is bound on its NW margin by a steep south-dipping thrust fault that has also accommodated sinistral strike-slip displacements. The Nanjieshan consists of parallel, but offset basement ridges that record NNW and SSE thrust displacements and sinistral strike-slip. Regional folds characterize the extreme eastern Nanjieshan perhaps above blind thrust faults which are emergent further west. At the surface, local fault reactivation of basement fabrics is an important control on the kinematics of deformation. Previously published magnetotelluric data for the region suggest that the major faults of the Sanweishan and Nanjieshan ultimately root to the south within conductive zones that merge into the ATF. Therefore, although the southern margin of the Dunhuang Block focuses significant deformation along the ATF, the adjacent cratonic basement to the north is also affected. Collectively, the ATF and structurally linked Sanweishan and Nanjieshan fault array represent a regional asymmetric half-flower structure that is dominated by non-strain partitioned sinistral transpression. The NW-trending Dengdengshan thrust fault array near Yumen City appears to define the northeastern limit of the Sanweishan-Nanjieshan block, which may be viewed regionally as the most northern, but early-stage expression of Tibetan Plateau growth into a reluctantly deforming, mechanically stiff Archean craton.

  5. Strikes, solidarity and scabs. Union members participation norms and williengness to participate in strikes.

    NARCIS (Netherlands)

    Akkerman, A.; Born, M.; Torenvlied, R.

    2013-01-01

    This article studies how participation norms affect workers' willingness to strike. A factor analysis on the responses of 468 Dutch union members about appropriate behavior during a strike produces two factors. The first factor reflects a "solidarity norm" favoring group solidarity; the second

  6. A contribution to better understanding of structural characteristics and tectonic phases of the Boč region, Periadriatic Fault Zone

    Directory of Open Access Journals (Sweden)

    Lea Žibret

    2016-12-01

    Full Text Available The aim of this study was to determine properties of the tectonic contact between Permian/Mesozoic limestones and less competent Miocene clastites on the northeastern foothill of the Boč Mt. Because fault planes signifiantly mark the relief, this contact was studied by a detailed structural mapping, which showed that the Boč Mt. is limited by subvertical faults in its northeastern part. To ensure that mapped subvertical contact is compatible with regional geodynamics of the area, additionally paleostress analysis of fault-slip data was performed. Four individual paleostress tensor groups were documented in a wider Boč area and compared by published structural data from the border zone between Alps, Dinarides and Pannonian Basin. The oldest paleostress tensor group (Phase 1 is likely of Lower and Middle Miocene age and indicates SW-NE extension accommodated by W-E to WNW-ESE striking normal faults. Phase 2 can be correlated with Middle to Late Miocene NW-SE to WNWESE directed extension accommodated by NNE-SSW striking normal faults. Phase 3 is correlated with Late Miocene W-E directed contraction accommodated by N-S striking sinistral faults and NNE-SSW to NE-SW striking dextral faults. The youngest paleostress tensor group (Phase 4 fis well with Pliocene to Quaternary NNW-SSE to N-S directed contraction accommodated by NW-SE to W-E striking dextral faults and NE-SW striking reverse faults. Since the documented paleostress phases fis well with the geodynamic processes of the Alps-Dinarides-Carpathians territory the subvertical border in the northeastern part of Boč Mt. seems to be an acceptable structural solution. The study is important because the study area is located at interaction zone between two major Alpine fault systems: the Periadriatic and the Lavanttal faults.

  7. Continuity of the San Andreas Fault at San Gorgonio Pass

    Science.gov (United States)

    Carena, S.; Suppe, J.

    2002-12-01

    The San Andreas fault at San Gorgonio Pass does not have a clear surface trace and is considered aseismic. Our findings suggest in fact that the existence of a through-going vertical or near-vertical San Andreas fault between Yucaipa and North Palm Springs is highly unlikely. We mapped over 70 faults in the San Gorgonio Pass-San Bernardino Mountains region using the catalog of 43,500 relocated 1975-1998 earthquakes of Richards-Dinger and Shearer (2000). A clustering algorithm was applied to the relocated earthquakes in order to obtain tighter earthquake clouds and thus better-defined fault surfaces. The earthquakes were then imported into Gocad, a 3D modeling software that allowed us to separate earthquakes into coplanar clusters associated with different faults and fault strands and to fit optimized surfaces to them. We also used the catalog of 13,000 focal mechanisms of Hauksson (2000) to confirm the nature of the mapped faults. We were able to constrain the 3D geometry of the San Andreas fault near San Gorgonio Pass from the 3D geometry of the fault network surrounding it. None of these faults show any displacement due to an hypothetical sub-vertical San Andreas. The San Andreas fault must therefore rotate to much shallower dips, or lose its continuity at depths between 3 and 15 km The most likely configuration is the one where the San Andreas fault merges into the shallow-dipping San Gorgonio Pass thrust W of North Palm Springs. Strike-slip motion is taken up by both the thrust (the slip vector on the N. Palm Springs segment is reverse/right-lateral strike-slip) and by a series of NW striking faults in the footwall of the thrust. The W termination of the most active part of the San Gorgonio Pass thrust coincides with one of these footwall faults at depth, and with the south bend in the San Andreas fault strand N of Banning. This boundary also marks a change in the stress field, with a dominant strike-slip regime to the E (and localized thrusting between San

  8. Seismotectonics of southern Haiti: A new faulting model for the 12 January 2010 M7.0 earthquake

    Science.gov (United States)

    Saint Fleur, Newdeskarl; Feuillet, Nathalie; Grandin, Raphaël.; Jacques, Eric; Weil-Accardo, Jennifer; Klinger, Yann

    2015-12-01

    The prevailing consensus is that the 2010 Mw7.0 Haiti earthquake left the Enriquillo-Plantain Garden strike-slip fault (EPGF) unruptured but broke unmapped blind north dipping thrusts. Using high-resolution topography, aerial images, bathymetry, and geology, we identified previously unrecognized south dipping NW-SE striking active thrusts in southern Haiti. One of them, Lamentin thrust, cuts across the crowded city of Carrefour, extends offshore into Port-au-Prince Bay, and connects at depth with the EPGF. We propose that both faults broke in 2010. The rupture likely initiated on the thrust and propagated further along the EPGF due to unclamping. This scenario is consistent with geodetic, seismological, and field data. The 2010 earthquake increased the stress toward failure on the unruptured segments of the EPGF and on neighboring thrusts, significantly increasing the seismic hazard in the Port-au-Prince urban area. The numerous active thrusts recognized in that area must be considered for future evaluation of the seismic hazard.

  9. Structural analysis of an outcropping granite (Proterozoic basement of Yémen): faults and fractures distributions and scaling properties.

    Science.gov (United States)

    Le Garzic, Edouard; de L'Hamaide, Thibaut; Diraison, Marc; Géraud, Yves; de Urreiztieta, Marc; Hauville, Benoit; Champanhet, Jean-Michel

    2010-05-01

    Numerous deep fractured reservoirs in basement have risen in recent years for oil or geothermal production. Such reservoirs are often badly-known because of a lack of direct information. Indeed, structural models proposed are mostly based on 1D borehole data, and conventional geophysical methods like seismic profiles are not so good techniques to image basement structures. Therefore, understanding the effects of scale in the organization of fracture system is a key problem in modelling geometry of deep fractured reservoir. The aim of this study is to present a detailed structural analysis of an outcropping granite at different scales and to contribute to comprehension of scaling properties of faults systems. Multi-scale structural maps were produced by remote sensing techniques and field approaches in the granitic Proterozoic basement of Al-Mukalla (Yémen). This region, located at the Southern boundary of the Arabian Plate, has a Pan-African tectonic signature and then has undergone two phases of continental extension since Mesozoic times: Jurassic-Cretaceous and Oligo-Miocene rifting (i.e. Gulf of Aden opening). In a first time, very high resolution satellite imagery (QUICKBIRD) was used to construct map of structural lineaments from regional scale to micro-block scale (~1 km x 1 km). In a second time, field observations and fractures measurements performed at outcrop scale allow us to confirm suitability of satellite picking. Finally, description of the various structures existing in Burum's granite and characterization of geometrical and morphological features of faults, fractured corridors and joints enable us to interpret structural lineaments with better accuracy. Major faults strike N090°E and N120°E, whereas secondary structures strike N000°E and N040°E and are interpreted as minor faults, fractured corridors or joints. Consequently, brittle deformation is mainly characterised by structural blocks with parallelogram shaped with fault segments

  10. Fault Tolerant Feedback Control

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.

    2001-01-01

    An architecture for fault tolerant feedback controllers based on the Youla parameterization is suggested. It is shown that the Youla parameterization will give a residual vector directly in connection with the fault diagnosis part of the fault tolerant feedback controller. It turns out...... that there is a separation be-tween the feedback controller and the fault tolerant part. The closed loop feedback properties are handled by the nominal feedback controller and the fault tolerant part is handled by the design of the Youla parameter. The design of the fault tolerant part will not affect the design...

  11. Relationship between displacement and gravity change of Uemachi faults and surrounding faults of Osaka basin, Southwest Japan

    Science.gov (United States)

    Inoue, N.; Kitada, N.; Kusumoto, S.; Itoh, Y.; Takemura, K.

    2011-12-01

    The Osaka basin surrounded by the Rokko and Ikoma Ranges is one of the typical Quaternary sedimentary basins in Japan. The Osaka basin has been filled by the Pleistocene Osaka group and the later sediments. Several large cities and metropolitan areas, such as Osaka and Kobe are located in the Osaka basin. The basin is surrounded by E-W trending strike slip faults and N-S trending reverse faults. The N-S trending 42-km-long Uemachi faults traverse in the central part of the Osaka city. The Uemachi faults have been investigated for countermeasures against earthquake disaster. It is important to reveal the detailed fault parameters, such as length, dip and recurrence interval, so on for strong ground motion simulation and disaster prevention. For strong ground motion simulation, the fault model of the Uemachi faults consist of the two parts, the north and south parts, because of the no basement displacement in the central part of the faults. The Ministry of Education, Culture, Sports, Science and Technology started the project to survey of the Uemachi faults. The Disaster Prevention Institute of Kyoto University is carried out various surveys from 2009 to 2012 for 3 years. The result of the last year revealed the higher fault activity of the branch fault than main faults in the central part (see poster of "Subsurface Flexure of Uemachi Fault, Japan" by Kitada et al., in this meeting). Kusumoto et al. (2001) reported that surrounding faults enable to form the similar basement relief without the Uemachi faults model based on a dislocation model. We performed various parameter studies for dislocation model and gravity changes based on simplified faults model, which were designed based on the distribution of the real faults. The model was consisted 7 faults including the Uemachi faults. The dislocation and gravity change were calculated based on the Okada et al. (1985) and Okubo et al. (1993) respectively. The results show the similar basement displacement pattern to the

  12. Microstructural investigations on carbonate fault core rocks in active extensional fault zones from the central Apennines (Italy)

    Science.gov (United States)

    Cortinovis, Silvia; Balsamo, Fabrizio; Storti, Fabrizio

    2017-04-01

    The study of the microstructural and petrophysical evolution of cataclasites and gouges has a fundamental impact on both hydraulic and frictional properties of fault zones. In the last decades, growing attention has been payed to the characterization of carbonate fault core rocks due to the nucleation and propagation of coseismic ruptures in carbonate successions (e.g., Umbria-Marche 1997, L'Aquila 2009, Amatrice 2016 earthquakes in Central Apennines, Italy). Among several physical parameters, grain size and shape in fault core rocks are expected to control the way of sliding along the slip surfaces in active fault zones, thus influencing the propagation of coseismic ruptures during earthquakes. Nevertheless, the role of grain size and shape distribution evolution in controlling the weakening or strengthening behavior in seismogenic fault zones is still not fully understood also because a comprehensive database from natural fault cores is still missing. In this contribution, we present a preliminary study of seismogenic extensional fault zones in Central Apennines by combining detailed filed mapping with grain size and microstructural analysis of fault core rocks. Field mapping was aimed to describe the structural architecture of fault systems and the along-strike fault rock distribution and fracturing variations. In the laboratory we used a Malvern Mastersizer 3000 granulometer to obtain a precise grain size characterization of loose fault rocks combined with sieving for coarser size classes. In addition, we employed image analysis on thin sections to quantify the grain shape and size in cemented fault core rocks. The studied fault zones consist of an up to 5-10 m-thick fault core where most of slip is accommodated, surrounded by a tens-of-meters wide fractured damage zone. Fault core rocks consist of (1) loose to partially cemented breccias characterized by different grain size (from several cm up to mm) and variable grain shape (from very angular to sub

  13. Characteristics of the active Luoshan Fault since Late Pleistocene, North Central China

    Directory of Open Access Journals (Sweden)

    M. Fengying

    2003-06-01

    Full Text Available The Luoshan Fault located at the northeastern margin of Tibet plateau strikes roughly N-S, and is composed of six left-stepping sections with a total length of 60 km. Much evidence suggests that the Luoshan Fault is a reverse right-lateral strike-slip fault. The largest right-lateral strike-slip displacement and the most abundant dextral offset phenomena are located along the central section. Based on the right-lateral strike-slip offsets of the oldest alluvial fan, and of a gully and on the average displacement of the same order of gullies, the minimum slip-rate has been 2.15 ± 0.2 mm/yr since Late Pleistocene. Many surface rupture phenomena, such as fault scarps with fresh free-face, ground fissures, displacements of very young gullies, imply that a recent earthquake occurred along this fault. Combining the historical catalogue and our results, we believe that the 1561 A.D. earthquake was produced by the Luoshan Fault. Three paleoearthquakes were determined by means of paleoseismic studies along the Luoshan Fault: they occurred after 8200 ± 600 years BP, between 3130 ± 240 years BP and 4150 ± ± 120 years C.BP, and before 2230 ± 170 years BP, respectively.

  14. Simulating the Risk of Bird Strikes

    NARCIS (Netherlands)

    Metz, I.C.; Ellerbroek, J.; Muhlhausen, Thorsten; Kügler, D.; Hoekstra, J.M.

    2017-01-01

    This paper presents a fast-time simulation environment for assessing the risk of bird strikes in aviation. An existing air traffic simulator was enhanced in order to simulate air and bird traffic simultaneously and to recognize collisions between birds and aircraft. Furthermore, a method was

  15. The Front Line: No Strikes, Just Balls.

    Science.gov (United States)

    Unks, Gerald

    1979-01-01

    Recent actions of British teachers suggest an alternative to the teacher strike. Those teachers dramatically demonstrated their grievances by withholding the voluntary extra services they customarily perform. American teachers could accomplish the same end by collectively refusing to perform extraneous administrative services: collecting money,…

  16. When Lightning Strikes a Second Time

    Science.gov (United States)

    Allen, Kent

    2017-01-01

    The chances of lightning striking twice are infinitesimal, at best. What are the odds, in middle age, of being struck with a jarring bolt of figurative lightning, then a few months later being an eyewitness as the same sizzle in the sky jolts a group of students--those decision-makers of tomorrow? The author describes two experiences that proved…

  17. 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.

  18. Crustal Density Variation Along the San Andreas Fault Controls Its Secondary Faults Distribution and Dip Direction

    Science.gov (United States)

    Yang, H.; Moresi, L. N.

    2017-12-01

    The San Andreas fault forms a dominant component of the transform boundary between the Pacific and the North American plate. The density and strength of the complex accretionary margin is very heterogeneous. Based on the density structure of the lithosphere in the SW United States, we utilize the 3D finite element thermomechanical, viscoplastic model (Underworld2) to simulate deformation in the San Andreas Fault system. The purpose of the model is to examine the role of a big bend in the existing geometry. In particular, the big bend of the fault is an initial condition of in our model. We first test the strength of the fault by comparing the surface principle stresses from our numerical model with the in situ tectonic stress. The best fit model indicates the model with extremely weak fault (friction coefficient 200 kg/m3) than surrounding blocks. In contrast, the Mojave block is detected to find that it has lost its mafic lower crust by other geophysical surveys. Our model indicates strong strain localization at the jointer boundary between two blocks, which is an analogue for the Garlock fault. High density lower crust material of the Great Valley tends to under-thrust beneath the Transverse Range near the big bend. This motion is likely to rotate the fault plane from the initial vertical direction to dip to the southwest. For the straight section, north to the big bend, the fault is nearly vertical. The geometry of the fault plane is consistent with field observations.

  19. 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

  20. [Management of the hunger strike in prison].

    Science.gov (United States)

    Fayeulle, Stéphanie; Renou, Frédéric; Protais, Emmanuel; Hédouin, Valéry; Wartel, Guillaume; Yvin, Jean-Luc

    2010-10-01

    Entering prison can feed pre-existent behavior of demands or generate them. Several means of expression are then used. Hunger strike is an average privileged act. It belongs to prison culture. Estimate how practitioners working in prison take care of the hunger strikers. The study, realised in 2008, was led with all the Units of Consultations and Ambulatory Care in France. It is a declarative investigation where a medical testimony by unit was asked. From 174 "maisons d'arrêt" and establishments for punishment in France, 95 answers were obtained. This situation was already seen by 98,8% of the doctors. The motives for hunger strike were mainly judicial for "maisons d'arrêt" (70,1%) and prison motives for detention centers (68,7%). Mainly, doctors opted for a neutral attitude (63% of the cases). The hunger strikes were mostly brief (less than a week in 85% of the cases). Only 5,5% of the doctors proposed written information concerning the risks incurred during a fast. A doctor in 4 approximately (23%) was already witness to complications due to fasting. The fact that a patient may refuse care makes the medical approach difficult. Faced with such a situation, 45% of the doctors privileged their duty of care, 28% respected the patient's wishes, and 27% did not pronounce. From a therapeutic point of view, the place of treatment using vitamins was rarely recognized (32,7%). Hunger strike is rarely severe, but it is rather frequent in prison so that every doctor working there will be confronted with it. The refeeding syndrome seems often ignored. The coverage of hunger strike is governed by the law, but ethical questions stay in the appreciation of every doctor. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  1. 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 (p<0.05) as a result of retraining. The present study demonstrates that retraining from rearfoot strike 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.

  2. Fault detection and isolation in systems with parametric faults

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, Hans Henrik

    1999-01-01

    The problem of fault detection and isolation of parametric faults is considered in this paper. A fault detection problem based on parametric faults are associated with internal parameter variations in the dynamical system. A fault detection and isolation method for parametric faults is formulated...

  3. Iowa Bedrock Faults

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This fault coverage locates and identifies all currently known/interpreted fault zones in Iowa, that demonstrate offset of geologic units in exposure or subsurface...

  4. Design of fault simulator

    International Nuclear Information System (INIS)

    Gabbar, Hossam A.; Sayed, Hanaa E.; Osunleke, Ajiboye S.; Masanobu, Hara

    2009-01-01

    Fault simulator is proposed to understand and evaluate all possible fault propagation scenarios, which is an essential part of safety design and operation design and support of chemical/production processes. Process models are constructed and integrated with fault models, which are formulated in qualitative manner using fault semantic networks (FSN). Trend analysis techniques are used to map real time and simulation quantitative data into qualitative fault models for better decision support and tuning of FSN. The design of the proposed fault simulator is described and applied on experimental plant (G-Plant) to diagnose several fault scenarios. The proposed fault simulator will enable industrial plants to specify and validate safety requirements as part of safety system design as well as to support recovery and shutdown operation and disaster management.

  5. Layered Fault Management Architecture

    National Research Council Canada - National Science Library

    Sztipanovits, Janos

    2004-01-01

    ... UAVs or Organic Air Vehicles. The approach of this effort was to analyze fault management requirements of formation flight for fleets of UAVs, and develop a layered fault management architecture which demonstrates significant...

  6. High Resolution Seismic Reflection Survey for Coal Mine: fault detection

    Science.gov (United States)

    Khukhuudei, M.; Khukhuudei, U.

    2014-12-01

    High Resolution Seismic Reflection (HRSR) methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration. Modern coal mining requires certainly about geological faults and structural features. This paper focuses on 2D Seismic section mapping results from an "Zeegt" lignite coal mine in the "Mongol Altai" coal basin, which required the establishment of major structure for faults and basement. HRSR method was able to detect subsurface faults associated with the major fault system. We have used numerical modeling in an ideal, noise free environment with homogenous layering to detect of faults. In a coal mining setting where the seismic velocity of the high ranges from 3000m/s to 3600m/s and the dominant seismic frequency is 100Hz, available to locate faults with a throw of 4-5m. Faults with displacements as seam thickness detected down to several hundred meter beneath the surface.

  7. Fault plane solutions as related to known geological faults in and near India

    Directory of Open Access Journals (Sweden)

    N. SRIVASTAVA

    1975-05-01

    Full Text Available Based on the focal mechanism solutions of newly determined solutions, and other recent workers the correlation between one of the nodal planes and the geological faults has been discussed for three regions namely Kashmir, Central Himalayas and northeast India including Assam. The variability between multiple solutions reported for some earthquakes and the limitations in the choice of the nodal plane from /'-wave solutions have been brought out. It is seen that no standard criteria either on the basis of isoseismals or of aftershocks can be used to distinguish the fault plane from the auxiliary plane. It has been found that in general there is good agreement between one of the nodal planes and the geological faults in Kashmir and the Central Himalayas. In northeast India, the strike directions obtained from the mechanism solutions generally agree with the trends of the main thrusts but the dip direction for shocks originating in the India-Burma border

  8. Investigation of the Meers fault in southwestern Oklahoma

    International Nuclear Information System (INIS)

    Luza, K.V.; Madole, R.F.; Crone, A.J.

    1987-08-01

    The Meers fault is part of a major system of NW-trending faults that form the boundary between the Wichita Mountains and the Anadarko basin in southwestern Oklahoma. A portion of the Meers fault is exposed at the surface in northern Comanche County and strikes approximately N. 60 0 W. where it offsets Permian conglomerate and shale for at least 26 km. The scarp on the fault is consistently down to the south, with a maximum relief of 5 m near the center of the fault trace. Quaternary stratigraphic relationships and 10 14 C age dates constrain the age of the last movement of the Meers fault. The last movement postdates the Browns Creek Alluvium, late Pleistocene to early Holocene, and predates the East Cache Alluvium, 100 to 800 yr B.P. Fan alluvium, produced by the last fault movement, buried a soil that dates between 1400 and 1100 yr B.P. Two trenches excavated across the scarp near Canyon Creek document the near-surface deformation and provide some general information on recurrence. Trench 1 was excavated in the lower Holocene part of the Browns Creek Alluvium, and trench 2 was excavated in unnamed gravels thought to be upper Pleistocene. Flexing and warping was the dominant mode of deformation that produced the scarp. The stratigraphy in both trenches indicates one surface-faulting event, which implies a lengthy recurrence interval for surface faulting on this part of the fault. Organic-rich material from two samples that postdate the last fault movement yielded 14 C ages between 1600 and 1300 yr B.P. These dates are in excellent agreement with the dates obtained from soils buried by the fault-related fan alluvium

  9. Evaluation of blade-strike models for estimating the biological performance of large Kaplan hydro turbines

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carlson, T. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ploskey, G. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richmond, M. C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2005-11-01

    Bio-indexing of hydro turbines has been identified as an important means to optimize passage conditions for fish by identifying operations for existing and new design turbines that minimize the probability of injury. Cost-effective implementation of bio-indexing requires the use of tools such as numerical and physical turbine models to generate hypotheses for turbine operations that can be tested at prototype scales using live fish. Blade strike has been proposed as an index variable for the biological performance of turbines. Report reviews an evaluation of the use of numerical blade-strike models as a means with which to predict the probability of blade strike and injury of juvenile salmon smolt passing through large Kaplan turbines on the mainstem Columbia River.

  10. 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

  11. Fault tolerant computing systems

    International Nuclear Information System (INIS)

    Randell, B.

    1981-01-01

    Fault tolerance involves the provision of strategies for error detection damage assessment, fault treatment and error recovery. A survey is given of the different sorts of strategies used in highly reliable computing systems, together with an outline of recent research on the problems of providing fault tolerance in parallel and distributed computing systems. (orig.)

  12. Performance based fault diagnosis

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik

    2002-01-01

    Different aspects of fault detection and fault isolation in closed-loop systems are considered. It is shown that using the standard setup known from feedback control, it is possible to formulate fault diagnosis problems based on a performance index in this general standard setup. It is also shown...

  13. 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

  14. Holocene earthquakes and right-lateral slip on the left-lateral Darrington-Devils Mountain fault zone, northern Puget Sound, Washington

    Science.gov (United States)

    Personius, Stephen F.; Briggs, Richard W.; Nelson, Alan R.; Schermer, Elizabeth R; Maharrey, J. Zebulon; Sherrod, Brian; Spaulding, Sarah A.; Bradley, Lee-Ann

    2014-01-01

    Sources of seismic hazard in the Puget Sound region of northwestern Washington include deep earthquakes associated with the Cascadia subduction zone, and shallow earthquakes associated with some of the numerous crustal (upper-plate) faults that crisscross the region. Our paleoseismic investigations on one of the more prominent crustal faults, the Darrington–Devils Mountain fault zone, included trenching of fault scarps developed on latest Pleistocene glacial sediments and analysis of cores from an adjacent wetland near Lake Creek, 14 km southeast of Mount Vernon, Washington. Trench excavations revealed evidence of a single earthquake, radiocarbon dated to ca. 2 ka, but extensive burrowing and root mixing of sediments within 50–100 cm of the ground surface may have destroyed evidence of other earthquakes. Cores in a small wetland adjacent to our trench site provided stratigraphic evidence (formation of a laterally extensive, prograding wedge of hillslope colluvium) of an earthquake ca. 2 ka, which we interpret to be the same earthquake documented in the trenches. A similar colluvial wedge lower in the wetland section provides possible evidence for a second earthquake dated to ca. 8 ka. Three-dimensional trenching techniques revealed evidence for 2.2 ± 1.1 m of right-lateral offset of a glacial outwash channel margin, and 45–70 cm of north-side-up vertical separation across the fault zone. These offsets indicate a net slip vector of 2.3 ± 1.1 m, plunging 14° west on a 286°-striking, 90°-dipping fault plane. The dominant right-lateral sense of slip is supported by the presence of numerous Riedel R shears preserved in two of our trenches, and probable right-lateral offset of a distinctive bedrock fault zone in a third trench. Holocene north-side-up, right-lateral oblique slip is opposite the south-side-up, left-lateral oblique sense of slip inferred from geologic mapping of Eocene and older rocks along the fault zone. The cause of this slip reversal is

  15. Seismogenic faulting in the Meruoca granite, NE Brazil, consistent with a local weak fracture zone.

    Science.gov (United States)

    Moura, Ana Catarina A; Oliveira, Paulo H S DE; Ferreira, Joaquim M; Bezerra, Francisco H R; Fuck, Reinhardt A; Nascimento, Aderson F DO

    2014-10-24

    A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geological structures in the Meruoca granite. We carried out geological mapping in the epicentral area, analyzed the mineralogy of fault rocks, and compared the seismically-defined Riacho Fundo fault with geological data. We concluded that the seismically-defined fault coincides with ∼E-W-striking faults observed at outcrop scale and a swarm of Mesozoic basalt dikes. We propose that seismicity reactivated brittle structures in the Meruoca granite. Our study highlights the importance of geological mapping and mineralogical analysis in order to establish the relationships between geological structures and seismicity at a given area.

  16. Seismogenic faulting in the Meruoca granite, NE Brazil, consistent with a local weak fracture zone

    Directory of Open Access Journals (Sweden)

    ANA CATARINA A. MOURA

    2014-12-01

    Full Text Available A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geological structures in the Meruoca granite. We carried out geological mapping in the epicentral area, analyzed the mineralogy of fault rocks, and compared the seismically-defined Riacho Fundo fault with geological data. We concluded that the seismically-defined fault coincides with ∼E–W-striking faults observed at outcrop scale and a swarm of Mesozoic basalt dikes. We propose that seismicity reactivated brittle structures in the Meruoca granite. Our study highlights the importance of geological mapping and mineralogical analysis in order to establish the relationships between geological structures and seismicity at a given area.

  17. Activity of the Mill Creek and Mission Creek fault strands of the San Andreas fault through the San Gorgonio Pass

    Science.gov (United States)

    Morelan, A. E., III; Oskin, M. E.; Valentine, M.

    2016-12-01

    We present new observations that constrain the recent slip history of the Mill Creek and Mission Creek strands of the San Andreas fault. These faults are the northern strands of a complex series of strike-slip and thrust faults through the San Gorgonio Pass stepover, an important structural barrier that affects seismic hazard in southern California. Understanding the activity on each of the faults in this complex region will reveal the potential for large, throughgoing San Andreas fault ruptures. The Mill Creek fault strand cuts the base of the upper Raywood Flat fill, a 50 m thick package of debris-flow deposits. However, the upper section of these deposits overlap, and are not cut by the fault. On the surface of this deposit, a 15 m-wide channel, flanked by bouldery debris-flow levees, crosses the projection of the Mill Creek fault without evidence of offset. We collected boulder-top samples for cosmogenic exposure age-dating of these levees and present preliminary results. Additionally, we mapped inset terraces along the incised channel of the East Fork Whitewater River drainage that also do not show evidence of fault offset, and we collected a depth profile through the uppermost Raywood Flat fill in order to further assess its age. Along the Mission Creek strand, newly devegetated B4 airborne lidar data reveals fault scarps cutting across hillslopes and alluvial fans between the San Bernardino strand and lower Raywood Flat for a distance of 4 km. We identify a lateral offset of 4-6 m in an alluvial fan deposit within a tributary of Banning canyon, and sampled a suite of boulders to estimate the age of this deposit. This site shows that the Mission Creek fault is active and could rupture through the San Gorgonio Pass, bypassing the structural complexity of the San Gorgonio Pass thrust to the south. Conversely, the Mill Creek fault appears to be inactive through the pass since the latest Pleistocene.

  18. Strike-slip and extrusion tectonics of the Greater Caucasus-Kopetdagh region

    Science.gov (United States)

    Kopp, M. L.

    2012-04-01

    In the Paleogene-Early Miocene, the areas of the modern Greater Caucasus and Kopetdagh were occupied by marginal seas (parts of the Paratethys intracontinental sea) inheriting the Cretaceous back-arc basins. In the Early Miocene, a collisional compression of the seas began at the time when the Arabian plate detached from Africa to move northward. The compression proceeded in a good accordance with the Arabia movement that was manifested in a general synchroneity of the Late Alpine orogenies in the Caucasus and Kopetdagh with the rifting and spreading phases in the Aden Gulf and the Red Sea. The earliest orogeny was the Styrian one of the terminal Early Miocene. It corresponds to the initial stage of the rift opening and was mostly pronounced in the east, in Kopetdagh and East Iran, where a recent structure has been formed by the initial Middle Miocene. In the Greater Caucasus, the Styrian deformations occurred in its central part only (i.e., in front of the Arabian plate northern tip) where the main Caucasian thrusts and conjugate asymmetrical megaanticline of the Central Caucasus were formed. An essential feature of the earliest, Styrian, structure of the whole Caucasus-Kopetdagh region was a series of regional right-lateral strike-slip faults. In the Kopetdagh, the strike-slips have no submeridional but northwestern direction although they occurred in the northern continuation of the submeridional right-lateral strike-slip faults framing the Lut block. In the Caucasus, they became even sublatitudinal, in parallel with the North Anatolian fault, thus constituting a single domain with the latter. So, the right-lateral strike-slip faults of East Iran, Kopetdagh, and the Caucasus compose an extensive arc convex to the north and appeared probably as a result of the right-lateral shear caused by the known counterclockwise rotation of the Arabian lithospheric plate. The Middle Miocene was characterized by a tectonic pause both in the Red Sea-Aden rift system and in the

  19. Modulation of Crustal Faulting in the Crescent Terrane by the Volume of Underthrust Accretionary Complex Along the Washington Cascadia Forearc

    Science.gov (United States)

    Brocher, T. M.

    2017-12-01

    Amphibious seismic experiments reveal widespread underthrusting of Cascadia accretionary rocks beneath basalts of the Crescent terrane, a large igneous province in the Washington forearc. Along margin variations in the volumes of the underthrust accretionary rocks appear to modulate the faulting within the overlying Crescent terrane, which hosts nearly all of the seismicity in the Washington forearc: the underlying accretionary rocks appear to deform aseismically. The underthrusting and underplating of large volumes of accretionary rocks on the Olympic Peninsula have uplifted and completely eroded a significant volume of the Crescent terrane, affecting the load-bearing strength of the forearc. I propose that as a consequence, the remnant Crescent terrane is actively deforming, as evidenced by the concentrated seismicity within it beneath Puget Lowland. This seismicity, focal mechanisms, fault geometries, and seismic tomography indicate that clockwise rotation and north-south compression of the forearc crust inferred from GPS data are accommodated by numerous thrust and strike slip faults in the remnant Crescent terrane. In addition to the spatial association between the erosion of the Crescent terrane on the Olympic Peninsula and the crustal faulting beneath Puget Lowland, support for the interpretation that the two are related also derives from the temporal coincidence between the mid to late Miocene uplift of the Crescent terrane on the peninsula and the mid-Miocene initiation of the thrust faulting in the lowland. In contrast, the underthrusting and underplating of lower volumes of accretionary rocks in the Washington forearc south of the Olympic Peninsula correlate with lower rates of crustal seismicity. These lower volumes of accretionary rocks have not caused the removal of a significant fraction of the Crescent terrane, resulting in a stronger, more structurally coherent Crescent terrane that deforms at lower rate than to the north.

  20. Transfer fault earthquake in compressionally reactivated back-arc failed rift: 1948 Fukui earthquake (M7.1), Japan

    Science.gov (United States)

    Ishiyama, Tatsuya; Kato, Naoko; Sato, Hiroshi; Koshiya, Shin

    2017-04-01

    Back-arc rift structures in many subduction zones are recognized as mechanically and thermally weak zones that possibly play important roles in strain accommodation at later post-rift stages within the overriding plates. In case of Miocene back-arc failed rift structures in the Sea of Japan in the Eurasian-Pacific subduction system, the mechanical contrasts between the crustal thrust wedges of the pre-rift continental crust and high velocity lower crust have fundamentally controlled the styles of post-rift, Quaternary active deformation (Ishiyama et al. 2016). In this study, we show a possibility that strike-slip M>7 devastating earthquakes in this region have been gregion enerated by reactivation of transfer faults highly oblique to the rift axes. The 1948 Fukui earthquake (M7.1), onshore shallow seismic event with a strike-slip faulting mechanism (Kanamori, 1973), resulted in more than 3,500 causalities and destructive damages on the infrastructures. While geophysical analyses on geodetic measurements based on leveling and triangulation networks clearly show coseismic left-lateral fault slip on a NNW striking vertical fault plane beneath the Fukui plain (Sagiya, 1999), no evidence for coseismic surface rupture has been identified based on both post-earthquake intensive fieldwork and recent reexamination of stereopair interpretations using 1/3,000 aerial photographs taken in 1948 (Togo et al., 2000). To find recognizable fault-related structures that deform Neogene basin fill sediments, we collected new 9.6-km-long high-resolution seismic reflection data across the geodetically estimated fault plane and adjacent subparallel active strike slip faults, using 925 offline recorders and Envirovib truck as a seismic source. A depth-converted section to 1.5 km depth contains discontinuous seismic reflectors correlated to Miocene volcaniclastic deposits and depression of the overlying Plio-Pleistocene sediments above the geodetically determined fault plane. We interpreted

  1. Perspective View, San Andreas Fault

    Science.gov (United States)

    2000-01-01

    The prominent linear feature straight down the center of this perspective view is California's famous San Andreas Fault. The image, created with data from NASA's Shuttle Radar Topography Mission (SRTM), will be used by geologists studying fault dynamics and landforms resulting from active tectonics. This segment of the fault lies west of the city of Palmdale, Calif., about 100 kilometers (about 60 miles) northwest of Los Angeles. The fault is the active tectonic boundary between the North American plate on the right, and the Pacific plate on the left. Relative to each other, the Pacific plate is moving away from the viewer and the North American plate is moving toward the viewer along what geologists call a right lateral strike-slip fault. Two large mountain ranges are visible, the San Gabriel Mountains on the left and the Tehachapi Mountains in the upper right. Another fault, the Garlock Fault lies at the base of the Tehachapis; the San Andreas and the Garlock Faults meet in the center distance near the town of Gorman. In the distance, over the Tehachapi Mountains is California's Central Valley. Along the foothills in the right hand part of the image is the Antelope Valley, including the Antelope Valley California Poppy Reserve. The data used to create this image were acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000.This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour

  2. Fault Detection for Quantized Networked Control Systems

    Directory of Open Access Journals (Sweden)

    Wei-Wei Che

    2013-01-01

    Full Text Available The fault detection problem in the finite frequency domain for networked control systems with signal quantization is considered. With the logarithmic quantizer consideration, a quantized fault detection observer is designed by employing a performance index which is used to increase the fault sensitivity in finite frequency domain. The quantized measurement signals are dealt with by utilizing the sector bound method, in which the quantization error is treated as sector-bounded uncertainty. By using the Kalman-Yakubovich-Popov (GKYP Lemma, an iterative LMI-based optimization algorithm is developed for designing the quantized fault detection observer. And a numerical example is given to illustrate the effectiveness of the proposed method.

  3. ["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.

  4. Central hyperadrenergic state after lightning strike.

    Science.gov (United States)

    Parsaik, Ajay K; Ahlskog, J Eric; Singer, Wolfgang; Gelfman, Russell; Sheldon, Seth H; Seime, Richard J; Craft, Jennifer M; Staab, Jeffrey P; Kantor, Birgit; Low, Phillip A

    2013-08-01

    To describe and review autonomic complications of lightning strike. Case report and laboratory data including autonomic function tests in a subject who was struck by lightning. A 24-year-old man was struck by lightning. Following that, he developed dysautonomia, with persistent inappropriate sinus tachycardia and autonomic storms, as well as posttraumatic stress disorder (PTSD) and functional neurologic problems. The combination of persistent sinus tachycardia and episodic exacerbations associated with hypertension, diaphoresis, and agitation was highly suggestive of a central hyperadrenergic state with superimposed autonomic storms. Whether the additional PTSD and functional neurologic deficits were due to a direct effect of the lightning strike on the central nervous system or a secondary response is open to speculation.

  5. Improving work conditions through strike: Examination of nurses' attitudes through perceptions of two physician strikes in Israel.

    Science.gov (United States)

    Gafni-Lachter, Liat; Admi, Hanna; Eilon, Yael; Lachter, Jesse

    2017-01-01

    Strikes are means to influence policies related to working conditions, yet raise ethical dilemmas for healthcare workers. Nurse strikes have become more prominent around the world. To assess the change in Israeli nurses' attitudes towards strikes in light of two physician strikes that have preceded a nursing strike. An anonymous survey was administered once in 2000 (N = 106) and again in 2011 (n = 175) following 110 days of a physician strike, to assess nurses' attitudes towards the strike and resulting ethical issues. A statistically significant change (p working conditions related to professional and public health agendas.

  6. Fault-Tree Compiler

    Science.gov (United States)

    Butler, Ricky W.; Boerschlein, David P.

    1993-01-01

    Fault-Tree Compiler (FTC) program, is software tool used to calculate probability of top event in fault tree. Gates of five different types allowed in fault tree: AND, OR, EXCLUSIVE OR, INVERT, and M OF N. High-level input language easy to understand and use. In addition, program supports hierarchical fault-tree definition feature, which simplifies tree-description process and reduces execution time. Set of programs created forming basis for reliability-analysis workstation: SURE, ASSIST, PAWS/STEM, and FTC fault-tree tool (LAR-14586). Written in PASCAL, ANSI-compliant C language, and FORTRAN 77. Other versions available upon request.

  7. Information Based Fault Diagnosis

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2008-01-01

    Fault detection and isolation, (FDI) of parametric faults in dynamic systems will be considered in this paper. An active fault diagnosis (AFD) approach is applied. The fault diagnosis will be investigated with respect to different information levels from the external inputs to the systems....... These inputs are disturbance inputs, reference inputs and auxilary inputs. The diagnosis of the system is derived by an evaluation of the signature from the inputs in the residual outputs. The changes of the signatures form the external inputs are used for detection and isolation of the parametric faults....

  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. 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. The Evaluation Method of the Lightning Strike on Transmission Lines Aiming at Power Grid Reliability

    Science.gov (United States)

    Wen, Jianfeng; Wu, Jianwei; Huang, Liandong; Geng, Yinan; Yu, zhanqing

    2018-01-01

    Lightning protection of power system focuses on reducing the flashover rate, only distinguishing by the voltage level, without considering the functional differences between the transmission lines, and being lack of analysis the effect on the reliability of power grid. This will lead lightning protection design of general transmission lines is surplus but insufficient for key lines. In order to solve this problem, the analysis method of lightning striking on transmission lines for power grid reliability is given. Full wave process theory is used to analyze the lightning back striking; the leader propagation model is used to describe the process of shielding failure of transmission lines. The index of power grid reliability is introduced and the effect of transmission line fault on the reliability of power system is discussed in detail.

  11. Fault isolability conditions for linear systems with additive faults

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, Jakob

    2006-01-01

    In this paper, we shall show that an unlimited number of additive single faults can be isolated under mild conditions if a general isolation scheme is applied. Multiple faults are also covered. The approach is algebraic and is based on a set representation of faults, where all faults within a set...... can occur simultaneously, whereas faults belonging to different fault sets appear disjoint in time. The proposed fault detection and isolation (FDI) scheme consists of three steps. A fault detection (FD) step is followed by a fault set isolation (FSI) step. Here the fault set is isolated wherein...... the faults have occurred. The last step is a fault isolation (FI) of the faults occurring in a specific fault set, i.e. equivalent with the standard FI step....

  12. 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.

  13. 3D Dynamic Rupture Simulations along the Wasatch Fault, Utah, Incorporating Rough-fault Topography

    Science.gov (United States)

    Withers, Kyle; Moschetti, Morgan

    2017-04-01

    Studies have found that the Wasatch Fault has experienced successive large magnitude (>Mw 7.2) earthquakes, with an average recurrence interval near 350 years. To date, no large magnitude event has been recorded along the fault, with the last rupture along the Salt Lake City segment occurring 1300 years ago. Because of this, as well as the lack of strong ground motion records in basins and from normal-faulting earthquakes worldwide, seismic hazard in the region is not well constrained. Previous numerical simulations have modeled deterministic ground motion in the heavily populated regions of Utah, near Salt Lake City, but were primarily restricted to low frequencies ( 1 Hz). Our goal is to better assess broadband ground motions from the Wasatch Fault Zone. Here, we extend deterministic ground motion prediction to higher frequencies ( 5 Hz) in this region by using physics-based spontaneous dynamic rupture simulations along a normal fault with characteristics derived from geologic observations. We use a summation by parts finite difference code (Waveqlab3D) with rough-fault topography following a self-similar fractal distribution (over length scales from 100 m to the size of the fault) and include off-fault plasticity to simulate ruptures > Mw 6.5. Geometric complexity along fault planes has previously been shown to generate broadband sources with spectral energy matching that of observations. We investigate the impact of varying the hypocenter location, as well as the influence that multiple realizations of rough-fault topography have on the rupture process and resulting ground motion. We utilize Waveqlab3's computational efficiency to model wave-propagation to a significant distance from the fault with media heterogeneity at both long and short spatial wavelengths. These simulations generate a synthetic dataset of ground motions to compare with GMPEs, in terms of both the median and inter and intraevent variability.

  14. The Effects of Pre-stress Assumptions on Dynamic Rupture with Complex Fault Geometry in the San Gorgonio Pass, CA Region

    Science.gov (United States)

    Kyriakopoulos, C.; Tarnowski, J. M.; Oglesby, D. D.

    2016-12-01

    We use 3D dynamic finite element models to investigate potential rupture paths of earthquakes propagating along faults in the western San Gorgonio Pass (SGP) region. The SGP is a structurally complex region along the San Andreas fault system (SAF) in southern California. We focus on the San Bernardino strand of the SAF, the San Gorgonio Pass Fault Zone, and a portion of the Garnet Hill strand of the SAF. The San Bernardino and Garnet Hill strands are predominately right-lateral strike-slip faults. Thrust faults dominate the San Gorgonio Pass Fault Zone, with small right-lateral tear faults between the thrust faults. We use the finite element code FaultMod (Barall, 2009) to observe differences in rupture propagation along a meshed fault geometry that reflects most of the surface trace complexity. We test three different types of pre-stress assumptions: 1) constant tractions, 2) regional stress regimes, and 3) long-term stressing rates from quasi-static crustal deformation modeling. Models with constant tractions assume pure right-lateral strike-slip motion on the San Bernardino and Garnet Hill strands and oblique thrust/right-lateral strike-slip motion on the San Gorgonio Pass Fault Zone. Preliminary results from models with constant tractions suggest that the complexity of the fault geometry may inhibit rupture propagation, depending on nucleation location.

  15. Viscoelastic shear zone model of a strike-slip earthquake cycle

    Science.gov (United States)

    Pollitz, F.F.

    2001-01-01

    I examine the behavior of a two-dimensional (2-D) strike-slip fault system embedded in a 1-D elastic layer (schizosphere) overlying a uniform viscoelastic half-space (plastosphere) and within the boundaries of a finite width shear zone. The viscoelastic coupling model of Savage and Prescott [1978] considers the viscoelastic response of this system, in the absence of the shear zone boundaries, to an earthquake occurring within the upper elastic layer, steady slip beneath a prescribed depth, and the superposition of the responses of multiple earthquakes with characteristic slip occurring at regular intervals. So formulated, the viscoelastic coupling model predicts that sufficiently long after initiation of the system, (1) average fault-parallel velocity at any point is the average slip rate of that side of the fault and (2) far-field velocities equal the same constant rate. Because of the sensitivity to the mechanical properties of the schizosphere-plastosphere system (i.e., elastic layer thickness, plastosphere viscosity), this model has been used to infer such properties from measurements of interseismic velocity. Such inferences exploit the predicted behavior at a known time within the earthquake cycle. By modifying the viscoelastic coupling model to satisfy the additional constraint that the absolute velocity at prescribed shear zone boundaries is constant, I find that even though the time-averaged behavior remains the same, the spatiotemporal pattern of surface deformation (particularly its temporal variation within an earthquake cycle) is markedly different from that predicted by the conventional viscoelastic coupling model. These differences are magnified as plastosphere viscosity is reduced or as the recurrence interval of periodic earthquakes is lengthened. Application to the interseismic velocity field along the Mojave section of the San Andreas fault suggests that the region behaves mechanically like a ???600-km-wide shear zone accommodating 50 mm/yr fault

  16. INVESTIGATION OF HOLOCENE FAULTING PROPOSED C-746-U LANDFILL EXPANSION

    Energy Technology Data Exchange (ETDEWEB)

    Lettis, William [William Lettis & Associates, Inc.

    2006-07-01

    This report presents the findings of a fault hazard investigation for the C-746-U landfill's proposed expansion located at the Department of Energy's (DOE) Paducah Gaseous Diffusion Plant (PGDP), in Paducah, Kentucky. The planned expansion is located directly north of the present-day C-746-U landfill. Previous geophysical studies within the PGDP site vicinity interpret possible northeast-striking faults beneath the proposed landfill expansion, although prior to this investigation the existence, locations, and ages of these inferred faults have not been confirmed through independent subsurface exploration. The purpose of this investigation is to assess whether or not Holocene-active fault displacement is present beneath the footprint of the proposed landfill expansion.

  17. 3D Constraints On Fault Architecture and Strain Distribution of the Newport-Inglewood Rose Canyon and San Onofre Trend Fault Systems

    Science.gov (United States)

    Holmes, J. J.; Driscoll, N. W.; Kent, G. M.

    2017-12-01

    The Inner California Borderlands (ICB) is situated off the coast of southern California and northern Baja. The structural and geomorphic characteristics of the area record a middle Oligocene transition from subduction to microplate capture along the California coast. Marine stratigraphic evidence shows large-scale extension and rotation overprinted by modern strike-slip deformation. Geodetic and geologic observations indicate that approximately 6-8 mm/yr of Pacific-North American relative plate motion is accommodated by offshore strike-slip faulting in the ICB. The farthest inshore fault system, the Newport-Inglewood Rose Canyon (NIRC) Fault is a dextral strike-slip system that is primarily offshore for approximately 120 km from San Diego to the San Joaquin Hills near Newport Beach, California. Based on trenching and well data, the NIRC Fault Holocene slip rate is 1.5-2.0 mm/yr to the south and 0.5-1.0 mm/yr along its northern extent. An earthquake rupturing the entire length of the system could produce an Mw 7.0 earthquake or larger. West of the main segments of the NIRC Fault is the San Onofre Trend (SOT) along the continental slope. Previous work concluded that this is part of a strike-slip system that eventually merges with the NIRC Fault. Others have interpreted this system as deformation associated with the Oceanside Blind Thrust Fault purported to underlie most of the region. In late 2013, we acquired the first high-resolution 3D Parallel Cable (P-Cable) seismic surveys of the NIRC and SOT faults as part of the Southern California Regional Fault Mapping project. Analysis of stratigraphy and 3D mapping of this new data has yielded a new kinematic fault model of the area that provides new insight on deformation caused by interactions in both compressional and extensional regimes. For the first time, we can reconstruct fault interaction and investigate how strain is distributed through time along a typical strike-slip margin using 3D constraints on fault

  18. Dynamic fracture network around faults: implications for earthquake ruptures, ground motion and energy budget

    Science.gov (United States)

    Okubo, K.; Bhat, H. S.; Rougier, E.; Lei, Z.; Knight, E. E.; Klinger, Y.

    2017-12-01

    Numerous studies have suggested that spontaneous earthquake ruptures can dynamically induce failure in secondary fracture network, regarded as damage zone around faults. The feedbacks of such fracture network play a crucial role in earthquake rupture, its radiated wave field and the total energy budget. A novel numerical modeling tool based on the combined finite-discrete element method (FDEM), which accounts for the main rupture propagation and nucleation/propagation of secondary cracks, was used to quantify the evolution of the fracture network and evaluate its effects on the main rupture and its associated radiation. The simulations were performed with the FDEM-based software tool, Hybrid Optimization Software Suite (HOSSedu) developed by Los Alamos National Laboratory. We first modeled an earthquake rupture on a planar strike-slip fault surrounded by a brittle medium where secondary cracks can be nucleated/activated by the earthquake rupture. We show that the secondary cracks are dynamically generated dominantly on the extensional side of the fault, mainly behind the rupture front, and it forms an intricate network of fractures in the damage zone. The rupture velocity thereby significantly decreases, by 10 to 20 percent, while the supershear transition length increases in comparison to the one with purely elastic medium. It is also observed that the high-frequency component (10 to 100 Hz) of the near-field ground acceleration is enhanced by the dynamically activated fracture network, consistent with field observations. We then conducted the case study in depth with various sets of initial stress state, and friction properties, to investigate the evolution of damage zone. We show that the width of damage zone decreases in depth, forming "flower-like" structure as the characteristic slip distance in linear slip-weakening law, or the fracture energy on the fault, is kept constant with depth. Finally, we compared the fracture energy on the fault to the energy

  19. Lack of continuity of the San Andreas Fault in southern California: Three-dimensional fault models and earthquake scenarios

    Science.gov (United States)

    Carena, Sara; Suppe, John; Kao, Honn

    2004-04-01

    The 1200-km-long San Andreas Fault loses its apparent continuity in southern California near San Gorgonio Pass [, 1957], which raises significant questions given the dominant role of this fault in active California tectonics. What is the fundamental three-dimensional (3-D) geometry and kinematic behavior of the San Andreas fault system in this complex region? Is a throughgoing, if complex, San Andreas rupture from the Mojave Desert to the Coachella Valley possible? We have explored the issue of 3-D continuity by mapping over 60 faults in this region to depths of 15-20 km from hypocenter locations and focal mechanisms. We were able to constrain the 3-D geometry of the San Andreas fault zone (SAF) near San Gorgonio Pass from the 3-D geometry of the fault network surrounding it. The most likely configuration is for the San Andreas Fault to merge into the shallow-dipping San Gorgonio Pass thrust northwest of Indio. We concluded that there is no direct continuity at present but rather a network of faults, and the only kind of rupture possible for the SAF in this region is a complex rupture, involving both strike-slip and reverse faulting. GPS measurements also suggest that despite the fact that large motions must have occurred in the past based on offset geologic markers, only minor motion is occurring today in this area. Applying our findings about the fault geometry, we explored several simple earthquake scenarios to determine the most favorable conditions for a throughgoing rupture of the San Andreas fault system from the Mojave Desert to the Coachella Valley.

  20. Finite-fault scaling relations in Mexico

    Science.gov (United States)

    Rodríguez-Pérez, Quetzalcoatl; Ottemöller, Lars

    2013-06-01

    Earthquake source parameters are widely used for computing scaling laws. We estimated source parameters for earthquakes in the Gulf of California, and the Mexican subduction zone through teleseismic fault slip inversion. The scaling relations herein can provide useful information for studies focused on source characteristics and ground motions in Mexico. We derived source scaling relations to estimate fault dimensions, combined asperity area, ratio of combined asperity area to rupture area, maximum displacement, mean displacement, duration and seismic energy of subduction interplate earthquakes based on their moment magnitude. We do not developed scaling relationships for strike-slip events in the Gulf of California due to the reduced number of data, but compare source parameters. We analyzed differences in source parameters between the two types of earthquakes. Scaling relations were fitted with orthogonal regression and we analyzed the difference between our subduction zone relationships and previous ones. We determined 21 finite-fault slip distributions for earthquakes in the magnitude range of 6.5 authors based on different inversion methods to construct scaling relationships in a consistent manner. Within this study, we characterized heterogeneous slip models by determining source parameters on the asperities and on the background area, such as number of asperities, combined asperity area, stress drop on asperities, aspect ratio, strain and average stress drop. We found that the area of the asperities represented about 22 and 24 per cent of the total area for strike-slip, and reverse events respectively with two different criteria based on average slip and maximum displacement. Sensitivity tests were carried out to estimate the variability of slip patterns and source parameters by changing fault dimensions, subfault size and the number of stations. We observed robust slip solutions and reliable source parameter estimations resulting in robust scaling

  1. Evolution of the Puente Hills Thrust Fault

    Science.gov (United States)

    Bergen, K. J.; Shaw, J. H.; Dolan, J. F.

    2013-12-01

    deformation on the LA and SFS segments: an early period characterized by fault-propagation or structural wedge kinematics that terminates in the early Pleistocene, followed by a period of quiescence. The faults were subsequently reactivated in the middle Pleistocene and propagated upward to detachments, with the deformation characterized by fold-bend folding kinematics. Slip on the LA segment decreases to the West, suggesting lateral growth in that direction. Our work highlights the need to assess along-strike variability in slip rate when assessing the seismic hazard of a compressional fault, as marginal sites may significantly underestimate fault activity. Ponti, D. J. et al. A 3-Dimensional Model of Water-Bearing Sequences in the Dominguez Gap Region, Long Beach, California. US Geological Survey Open-File Report 1013 (2007).

  2. Chronology of Deformation Near the Iditarod-Nixon Fork Fault, West-Central Alaska

    Science.gov (United States)

    Perttu, B. K.; Wallace, W. K.; Newberry, R. J.; Layer, P. W.

    2010-12-01

    The Nixon Fork Mine is a Cu-Au deposit located 7 km south of the Iditarod-Nixon Fork (I-NF) fault. This fault strikes at ~060°, and can be traced for ~400 km, with a minimum dextral displacement of ~90 km. Proximity to the I-NF fault suggests it would be a dominant influence on deformation of the deposit, but the extent and timing of disruption are unknown. In order to reconstruct strain history and eventually understand structural evolution, we analyzed the orientations of geologic structures and dated representative K-bearing minerals and rocks. Felsic dikes, with 40Ar/39Ar ages of 69.6 ± 0.5 Ma and arc-type signatures, are cut by faults apparently related to the I-NF fault, but do not obviously cut such faults. Since no dikes are seen to cut faults, we know of no local fault motion prior to their intrusion. The northeast strike of the felsic dikes (n = 102; mean = 034° ± 10° ) requires σ3 oriented ~124°, at odds with the ~0° orientation inferred from the strike of the I-NF fault (~60°). The Nixon Fork pluton has approximately the same age and an overall elongation compatible with the felsic dikes. Mafic dikes, with 40Ar/39Ar ages of 62.8 ± 0.6 Ma, have within-plate signatures (average TiO2 = 2.48 wt%, Zr = 172 ppm, Nb = 58 ppm, Y = 25 ppm) and require a change in overall tectonic regime. Additionally, their north strike (n = 44; mean = 013° ± 10°) requires σ3 oriented ~103°, which is not compatible with σ3 (~0°) inferred from the right-lateral I-NF fault, and requires a different extension direction from the felsic dikes. We observed mafic dikes cut by faults with orientations compatible with right-lateral motion on the I-NF fault, and we propose that right-lateral motion on the I-NF fault began after mafic dike emplacement. Outcrop-scale fold axes trend north (n = 136; mean = 355° ± 10°). They are preferentially aligned perpendicular to the σ1 inferred for right-lateral motion on the I-NF fault and so are plausibly related to the I-NF fault

  3. 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.

  4. Making inference from wildlife collision data: inferring predator absence from prey strikes.

    Science.gov (United States)

    Caley, Peter; Hosack, Geoffrey R; Barry, Simon C

    2017-01-01

    Wildlife collision data are ubiquitous, though challenging for making ecological inference due to typically irreducible uncertainty relating to the sampling process. We illustrate a new approach that is useful for generating inference from predator data arising from wildlife collisions. By simply conditioning on a second prey species sampled via the same collision process, and by using a biologically realistic numerical response functions, we can produce a coherent numerical response relationship between predator and prey. This relationship can then be used to make inference on the population size of the predator species, including the probability of extinction. The statistical conditioning enables us to account for unmeasured variation in factors influencing the runway strike incidence for individual airports and to enable valid comparisons. A practical application of the approach for testing hypotheses about the distribution and abundance of a predator species is illustrated using the hypothesized red fox incursion into Tasmania, Australia. We estimate that conditional on the numerical response between fox and lagomorph runway strikes on mainland Australia, the predictive probability of observing no runway strikes of foxes in Tasmania after observing 15 lagomorph strikes is 0.001. We conclude there is enough evidence to safely reject the null hypothesis that there is a widespread red fox population in Tasmania at a population density consistent with prey availability. The method is novel and has potential wider application.

  5. Making inference from wildlife collision data: inferring predator absence from prey strikes

    Directory of Open Access Journals (Sweden)

    Peter Caley

    2017-02-01

    Full Text Available Wildlife collision data are ubiquitous, though challenging for making ecological inference due to typically irreducible uncertainty relating to the sampling process. We illustrate a new approach that is useful for generating inference from predator data arising from wildlife collisions. By simply conditioning on a second prey species sampled via the same collision process, and by using a biologically realistic numerical response functions, we can produce a coherent numerical response relationship between predator and prey. This relationship can then be used to make inference on the population size of the predator species, including the probability of extinction. The statistical conditioning enables us to account for unmeasured variation in factors influencing the runway strike incidence for individual airports and to enable valid comparisons. A practical application of the approach for testing hypotheses about the distribution and abundance of a predator species is illustrated using the hypothesized red fox incursion into Tasmania, Australia. We estimate that conditional on the numerical response between fox and lagomorph runway strikes on mainland Australia, the predictive probability of observing no runway strikes of foxes in Tasmania after observing 15 lagomorph strikes is 0.001. We conclude there is enough evidence to safely reject the null hypothesis that there is a widespread red fox population in Tasmania at a population density consistent with prey availability. The method is novel and has potential wider application.

  6. Geomorphic evidence of Quaternary tectonics within an underlap fault zone of southern Apennines, Italy

    Science.gov (United States)

    Giano, Salvatore Ivo; Pescatore, Eva; Agosta, Fabrizio; Prosser, Giacomo

    2018-02-01

    A composite seismic source, the Irpinia - Agri Valley Fault zone, located in the axial sector of the fold-and-thrust belt of southern Apennines, Italy, is investigated. This composite source is made up of a series of nearly parallel, NW-striking normal fault segments which caused many historical earthquakes. Two of these fault segments, known as the San Gregorio Magno and Pergola-Melandro, and the fault-related mountain fronts, form a wedge-shaped, right-stepping, underlap fault zone. This work is aimed at documenting tectonic geomorphology and geology of this underlap fault zone. The goal is to decipher the evidence of surface topographic interaction between two bounding fault segments and their related mountain fronts. In particular, computation of geomorphic indices such as mountain front sinuosity (Smf), water divide sinuosity (Swd), asymmetry factor (AF), drainage basin elongation (Bs), relief ratio (Rh), Hypsometry (HI), normalized steepness (Ksn), and concavity (θ) is integrated with geomorphological analysis, the geological mapping, and structural analysis in order to assess the recent activity of the fault scarp sets recognized within the underlap zone. Results are consistent with the NW-striking faults as those showing the most recent tectonic activity, as also suggested by presence of related slope deposits younger than 38 ka. The results of this work therefore show how the integration of a multidisciplinary approach that combines geomorphology, morphometry, and structural analyses may be key to solving tectonic geomorphology issues in a complex, fold-and-thrust belt configuration.

  7. Fault tolerant control for uncertain systems with parametric faults

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2006-01-01

    A fault tolerant control (FTC) architecture based on active fault diagnosis (AFD) and the YJBK (Youla, Jarb, Bongiorno and Kucera)parameterization is applied in this paper. Based on the FTC architecture, fault tolerant control of uncertain systems with slowly varying parametric faults...... is investigated. Conditions are given for closed-loop stability in case of false alarms or missing fault detection/isolation....

  8. Acute transient hemiparesis induced by lightning strike.

    Science.gov (United States)

    Rahmani, Seyed Hesam; Faridaalaee, Gholamreza; Jahangard, Samira

    2015-07-01

    According to data from the National Oceanic and Atmospheric Administration,in the years from 1959 to 1994, lightning was responsible for more than 3000 deaths and nearly 10,000 casualties. The most important characteristic features of lightning injuries are multisystem involvement and widely variable severity. Lightning strikes are primarily a neurologic injury that affects all 3 components of the nervous system: central, autonomic,and peripheral. Neurologic complications of lightning strikes vary from transient benign symptoms to permanent disability. Many patients experience a temporary paralysis called keraunoparalysis. Here we reported a 22-year-old mountaineer man with complaining of left sided hemiparesis after being hit by a lightning strike in the mountain 3 hours ago. There was no loss of consciousness at hitting time. On arrival the patient was alert, awake and hemodynamically stable. In neurologic examination cranial nerves were intact, left sided upper and lower extremity muscle force was I/V with a combination of complete sensory loss, and right-sided muscle force and sensory examination were normal. There is not any evidence of significant vascular impairment in the affected extremities. Brain MRI and CT scan and cervical MRI were normal. During 2 days of admission, with intravenous hydration, heparin 5000 unit SC q12hr and physical therapy of the affected limbs, motor and sensory function improved and was normal except mild paresthesia. He was discharged 1 day later for outpatient follow up while vitamin B1 100mg orally was prescribed.Paresthesia improved after 3 days without further sequels.

  9. Fracture structures of active Nojima fault, Japan, revealed by borehole televiewer imaging

    Science.gov (United States)

    Nishiwaki, T.; Lin, A.

    2017-12-01

    Most large intraplate earthquakes occur as slip on mature active faults, any investigation of the seismic faulting process and assessment of seismic hazards require an understanding of the nature of active fault damage zones as seismogenic source. In this study, we focus on the fracture structures of the Nojima Fault (NF) that triggered the 1995 Kobe Mw 7.2 earthquake using ultrasonic borehole televiewer (BHTV) images from a borehole wall. The borehole used in this study was drilled throughout the NF at 1000 m in depth by a science project of Drilling into Fault Damage Zone(DFDZ) in 2016 (Lin, 2016; Miyawaki et al., 2016). In the depth of consolidated sandstone and conglomerate of the Plio-Pleistocene Osaka-Group and mudstone and sandstone of the Miocene Kobe Group. The basement rock in the depth of >230 m consist of pre-Neogene granitic rock. Based on the observations of cores and analysis of the BHTV images, the main fault plane was identified at a depth of 529.3 m with a 15 cm thick fault gouge zone and a damage zone of 100 m wide developed in the both sides of the main fault plane. Analysis of the BHTV images shows that the fractures are concentrated in two groups: N45°E (Group-1), parallel to the general trend of the NF, and another strikes N70°E (Group-2), oblique to the fault with an angle of 20°. It is well known that Riedel shear structures are common within strike-slip fault zones. Previous studies show that the NF is a right-lateral strike-slip fault with a minor thrust component, and that the fault damage zone is characterized by Riedel shear structures dominated by Y shears (main faults), R shears and P foliations (Lin, 2001). We interpret that the fractures of Group (1) correspond to Y Riedel fault shears, and those of Group (2) are R shears. Such Riedel shear structures indicate that the NF is a right-lateral strike-slip fault which is activated under a regional stress field oriented to the direction close to east-west, coincident with that

  10. Do fault-related folds follow the same scaling law as their associated faults? A study using 3D seismic reflection data

    Science.gov (United States)

    Pitcher, Eleanor; Imber, Jonathan

    2016-04-01

    Fractal distributions are largely agreed to follow a power-law distribution. Power-law scaling relationships describe the size distribution of fault lengths or displacements. Being able to identify these scaling properties provides a powerful tool for predicting the numbers of geological structures, such as small-scale faults in sedimentary basins that are below the resolution of seismic reflection data. The aim of this study is to determine whether fault-related folds follow the same power law scaling properties, or if they follow a different scaling law. We use TrapTester to interpret a 3D seismic volume from the Gulf of Mexico to construct fault planes and cut-off lines along selected horizons in the vicinity of fault upper tip lines. Fault-related folds are particularly well developed above steeply plunging tip lines, but are discontinuous along the strike of the fault plane. Folding is less well developed on horizons that intersect, or lie close to, the locus of maximum throw (bullseye) of the fault plane. We then measured fold amplitudes and fault throws across these same horizons using a one-dimensional multi-line sampling approach. Graphs of fault throw and fold amplitude vs. distance parallel to fault strike show that folds occur where there is no resolvable fault throw, and that fault throw and fold amplitudes show an approximately inverse relationship. Close to the locus of maximum throw, there is largely just faulting, whilst at the upper tip line folding predominates. By plotting cumulative frequency against throw for the fault and fold data we can investigate whether the data follow a power law, log normal or exponential distribution. Plotting the data on log vs. log (power law), linear vs. log (log normal) and log vs. linear (exponential) axes allow us to establish which displays the best "straight-line fit". We observed that the fault throw data satisfied a straight-line on a log vs. log graph - implying a power law distribution - and also returned

  11. Lightning strike-induced brachial plexopathy

    Directory of Open Access Journals (Sweden)

    Amita N Bhargava

    2014-01-01

    Full Text Available We describe a patient who presented with a history of lightning strike injury. Following the injury, he sustained acute right upper limb weakness with pain. Clinically, the lesion was located to the upper and middle trunk of the right brachial plexus, and the same confirmed with electrophysiological studies. Nerve damage due to lightning injuries is considered very rare, and a plexus damage has been described infrequently, if ever. Thus, the proposed hypothesis that lightning rarely causes neuropathy, as against high-voltage electric current, due to its shorter duration of exposure not causing severe burns which lead to nerve damage, needs to be reconsidered.

  12. The Evergreen basin and the role of the Silver Creek fault in the San Andreas fault system, San Francisco Bay region, California

    Science.gov (United States)

    Jachens, Robert C.; Wentworth, Carl M.; Graymer, Russell W.; Williams, Robert; Ponce, David A.; Mankinen, Edward A.; Stephenson, William J.; Langenheim, Victoria

    2017-01-01

    The Evergreen basin is a 40-km-long, 8-km-wide Cenozoic sedimentary basin that lies mostly concealed beneath the northeastern margin of the Santa Clara Valley near the south end of San Francisco Bay (California, USA). The basin is bounded on the northeast by the strike-slip Hayward fault and an approximately parallel subsurface fault that is structurally overlain by a set of west-verging reverse-oblique faults which form the present-day southeastward extension of the Hayward fault. It is bounded on the southwest by the Silver Creek fault, a largely dormant or abandoned fault that splays from the active southern Calaveras fault. We propose that the Evergreen basin formed as a strike-slip pull-apart basin in the right step from the Silver Creek fault to the Hayward fault during a time when the Silver Creek fault served as a segment of the main route by which slip was transferred from the central California San Andreas fault to the Hayward and other East Bay faults. The dimensions and shape of the Evergreen basin, together with palinspastic reconstructions of geologic and geophysical features surrounding it, suggest that during its lifetime, the Silver Creek fault transferred a significant portion of the ∼100 km of total offset accommodated by the Hayward fault, and of the 175 km of total San Andreas system offset thought to have been accommodated by the entire East Bay fault system. As shown previously, at ca. 1.5–2.5 Ma the Hayward-Calaveras connection changed from a right-step, releasing regime to a left-step, restraining regime, with the consequent effective abandonment of the Silver Creek fault. This reorganization was, perhaps, preceded by development of the previously proposed basin-bisecting Mount Misery fault, a fault that directly linked the southern end of the Hayward fault with the southern Calaveras fault during extinction of pull-apart activity. Historic seismicity indicates that slip below a depth of 5 km is mostly transferred from the Calaveras

  13. Orientations of Pre-existing Structures along the Scarp of the Bilila-Mtakataka Fault in the Central Malawi Rift.

    Science.gov (United States)

    Elifritz, E. A.; Johnson, S.; Beresh, S. C. M.; Mendez, K.; Mynatt, W. G.; Mayle, M.; Laó-Dávila, D. A.; Atekwana, E. A.; Chindandali, P. R. N.; Chisenga, C.; Gondwe, S.; Mkumbwa, M.; Kalindekafe, L.; Kalaguluka, D.; Salima, J.

    2017-12-01

    The NW-SE Bilila-Mtakataka Fault is suggested to be 100 km in length and is located in the Malawi Rift, a portion of the magma-poor Western Branch of the East African Rift System. This fault is exposed south of Lake Malawi and occurs close to the epicenter of the 1989 6.2 magnitude Salima Earthquake. Moreover, it traverses rocks with inherited Precambrian fabrics that may control the modern rifting process. The effect of the orientation of the pre-existing fabric on the formation of this potentially seismogenic fault has not been well studied. In this project, we measured the older foliations, dikes, and joints in addition to younger faults and striations to understand how the active faulting of the Bilila-Mtakataka Fault is affected by the older fabric. The Fault is divided into 5 segments and 4 linkage zones. All four linkage zones were studied in detail and a Brunton compass was used to determine orientations of structures. The linkage zone between segments 1 and 2 occurs between a regional WNW-ESE joint and the border fault, which is identified by a zig-zag pattern in SRTM data. Precambrian gneiss is cut by oblique steeply-dipping faults in this area. Striations and layer offsets suggest both right-lateral and normal components. This segment strikes NE-SW, in contrast with the NW-SE average strike of the entire fault. The foliations, faults, dikes, and joints collected in this area strike NE-SW, therefore running parallel to the segment. The last 3 southern linkage zones all strike NW-SE and the linkage zone between segment 3 and 4 has a steep dip angle. Dip angles of structures vary from segment to segment, having a wide range of results. Nonetheless, all four linkage zones show structures striking parallel to its segment direction. The results show that pre-existing meso-scale and regional structures and faults strike parallel to the fault scarp. The parallelism of the structures suggest that they serve as planes of weakness, controlling the localization of

  14. Late Quaternary Normal Faulting and Hanging Wall Basin Evolution of the Southwestern Rift Margin from Gravity and Geology, B.C.S., MX and Exploring the Influence of Text-Figure Format on Introductory Geology Learning

    Science.gov (United States)

    Busch, Melanie M. D.

    2011-01-01

    An array of north-striking, left-stepping, active normal faults is situated along the southwestern margin of the Gulf of California. This normal fault system is the marginal fault system of the oblique-divergent plate boundary within the Gulf of California. To better understand the role of upper-crustal processes during development of an obliquely…

  15. Fault complexity associated with the 14 August 2003 Mw6.2 Lefkada, Greece, aftershock sequence

    Science.gov (United States)

    Karakostas, Vassilios; Papadimitriou, Eleftheria

    2010-10-01

    The M w6.2 Lefkada earthquake occurred on 14 August 2003 beneath the western coastline of Lefkada Island. The main shock was followed by an intense aftershock activity, which formed a narrow band extending over the western coast of the Island and the submarine area between Lefkada and Kefalonia Islands, whereas additional off fault aftershocks formed spatial clusters on the central and northwestern part of the Island. The aftershock spatial distribution revealed the activation of along-strike adjacent fault segment as well as of secondary faults close to the main rupture. The properties of the activated segments were illuminated by the precisely located aftershocks, fault plane solutions determination and the cross sections performed parallel and normal to their strike. The aftershock focal mechanisms exhibited mainly strike slip faulting throughout the activated area, although deviation of the dominant stress pattern is also observed. The results help to emphasize the importance of the identification of activated nearby fault segments possibly triggered by the main rupture. Because such segments are capable to produce moderate events causing appreciable damage, they should be viewed with caution in seismic hazard assessment in addition to the major regional faults.

  16. Evidence of Quaternary and recent activity along the Kyaukkyan Fault, Myanmar

    Science.gov (United States)

    Crosetto, Silvia; Watkinson, Ian M.; Soe Min; Gori, Stefano; Falcucci, Emanuela; Nwai Le Ngal

    2018-05-01

    Cenozoic right-lateral shear between the eastern Indian margin and Eurasia is expressed by numerous N-S trending fault systems inboard of the Sunda trench, including the Sagaing Fault. The most easterly of these fault systems is the prominent ∼500 km long Kyaukkyan Fault, on the Shan Plateau. Myanmar's largest recorded earthquake, Mw 7.7 on 23rd May 1912, focused near Maymyo, has been attributed to the Kyaukkyan Fault, but the area has experienced little significant seismicity since then. Despite its demonstrated seismic potential and remarkable topographic expression, questions remain about the Kyaukkyan Fault's neotectonic history.

  17. A proposal of surveying and evaluating system of active faults for earthquake assessment

    International Nuclear Information System (INIS)

    Miyakoshi, Katsuyoshi; Ueta, Keiichi; Hataya; Ryuta; Abe, Shintaro; Miura, Daisuke; Hamada, Takaomi; Aoyagi, Yasuhira; Inoue, Daiei

    2004-01-01

    1. Paleoseismology of the Itoigawa-Shizuoka Tectonic Line active fault system: We investigated co-seismic faulting activity of the Itoigawa-Shizuoka Tectonic Line active fault system (ISTL) to clarify behavioral segmentation of long and massive faults. Geomorphologic and geologic surveys, trench excavation, and seismic reflection survey in the southern to central parts of ISTL revealed paleoseismologic faulting events occurred in the last thousands years and characteristics of geometric, structural, and geomorphologic segments. Each paleoseismic event, co-seismic displacement of deposit, average slip rate, and recurrence intervals suggest that the latest paleo-earthquake occurred in 1700 cal y BP and involved multiple segments in the Okaya to the Shimotsuburai faults. The estimated surface rupture length for this event is up to 77 km or possibly up to 94 km long. The another latest event occurred after 1200 cal y BP at the Ichinose fault and adjacent active faults. In addition, ca. 1200 cal y BP event at the Gofukuji fault occurred and involved multiple segments in the northern ISTL. Behavioral boundaries of these distinctive paleoseismic events were present in segment boundaries of geometric characters and slip rate variation. In the ISTL, geometric segmentation and slip-rate variation likely coincide with the estimated behavioral segmentation. Therefore, this finding suggests that geometric segment and slip-rate variation play an important role to determine the size of the maximum behavioral segment. 2. Active fault study on the 1999 Taiwan Chichi Earthquake area: The earthquake fault was appeared along the Chelungpu Fault while the 1999 Chichi Earthquake has occurred. The N-S striking fault has been recognized as an active fault, however E-W direction earthquake fault has not been described before the earthquake as an active fault. The later fault appeared just beneath the Shihkang Dam and the dam was destroyed by the fault. This study revealed that the E

  18. Automatic fault extraction using a modified ant-colony algorithm

    International Nuclear Information System (INIS)

    Zhao, Junsheng; Sun, Sam Zandong

    2013-01-01

    The basis of automatic fault extraction is seismic attributes, such as the coherence cube which is always used to identify a fault by the minimum value. The biggest challenge in automatic fault extraction is noise, including that of seismic data. However, a fault has a better spatial continuity in certain direction, which makes it quite different from noise. Considering this characteristic, a modified ant-colony algorithm is introduced into automatic fault identification and tracking, where the gradient direction and direction consistency are used as constraints. Numerical model test results show that this method is feasible and effective in automatic fault extraction and noise suppression. The application of field data further illustrates its validity and superiority. (paper)

  19. 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.

  20. Earthquake Hazard and Segmented Fault Evolution, Hat Creek Fault, Northern California

    Science.gov (United States)

    Blakeslee, M. W.; Kattenhorn, S. A.

    2010-12-01

    indicates that surface rupture undergoes a 4.5 km right-step from the Active scarp west to the Rim, perhaps due to the fault responding to localized volcanic activity at Cinder Butte. The newly mapped segment ruptured repeatedly along the pre-existing Rim, creating a cumulative throw of up to 150 m. The addition of this segment increases the seismic risk in this area. Previous studies suggest that a surface breaking rupture along the Hat Creek fault could produce an earthquake magnitude of at least M 6.0. However, with the increase in rupture length, the fault system has the potential to produce at least a M 6.5. Finally, we consider the importance of deformation within segment overlap zones (relay ramps), which contribute to the distribution of fault throw, and can create inaccurate anomalies in throw profiles if not properly accounted for. Relay ramps tilt either toward the front fault segment or toward the back fault segment. We measure the change in elevation across relay ramps perpendicular to the fault strike to quantify the ramp contribution to fault throw, then incorporate this data into throw profiles to eliminate anomalous peaks or lows where segments overlap. More accurate throw profiles lead to better slip rate estimates for the fault system.

  1. Analysis of Simulated Aircraft Lightning Strikes and Their Electromagnetic Effects

    National Research Council Canada - National Science Library

    Gruden, James

    2001-01-01

    To survive the intense electromagnetic fields associated with a lightning strike, proper design of aircraft electrical control systems requires knowledge of the transient current pulse associated with a lightning strike...

  2. Development of Characterization Technology for Fault Zone Hydrology

    International Nuclear Information System (INIS)

    Karasaki, Kenzi; Onishi, Tiemi; Gasperikova, Erika; Goto, Junichi; Tsuchi, Hiroyuki; Miwa, Tadashi; Ueta, Keiichi; Kiho, Kenzo; Miyakawa, Kimio

    2010-01-01

    Several deep trenches were cut, and a number of geophysical surveys were conducted across the Wildcat Fault in the hills east of Berkeley, California. The Wildcat Fault is believed to be a strike-slip fault and a member of the Hayward Fault System, with over 10 km of displacement. So far, three boreholes of ∼ 150m deep have been core-drilled and borehole geophysical logs were conducted. The rocks are extensively sheared and fractured; gouges were observed at several depths and a thick cataclasitic zone was also observed. While confirming some earlier, published conclusions from shallow observations about Wildcat, some unexpected findings were encountered. Preliminary analysis indicates that Wildcat near the field site consists of multiple faults. The hydraulic test data suggest the dual properties of the hydrologic structure of the fault zone. A fourth borehole is planned to penetrate the main fault believed to lie in-between the holes. The main philosophy behind our approach for the hydrologic characterization of such a complex fractured system is to let the system take its own average and monitor a long term behavior instead of collecting a multitude of data at small length and time scales, or at a discrete fracture scale and to 'up-scale,' which is extremely tenuous.

  3. Development of Characterization Technology for Fault Zone Hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Karasaki, Kenzi; Onishi, Tiemi; Gasperikova, Erika; Goto, Junichi; Tsuchi, Hiroyuki; Miwa, Tadashi; Ueta, Keiichi; Kiho, Kenzo; MIyakawa, Kimio

    2010-08-06

    Several deep trenches were cut, and a number of geophysical surveys were conducted across the Wildcat Fault in the hills east of Berkeley, California. The Wildcat Fault is believed to be a strike-slip fault and a member of the Hayward Fault System, with over 10 km of displacement. So far, three boreholes of ~;; 150m deep have been core-drilled and borehole geophysical logs were conducted. The rocks are extensively sheared and fractured; gouges were observed at several depths and a thick cataclasitic zone was also observed. While confirming some earlier, published conclusions from shallow observations about Wildcat, some unexpected findings were encountered. Preliminary analysis indicates that Wildcat near the field site consists of multiple faults. The hydraulic test data suggest the dual properties of the hydrologic structure of the fault zone. A fourth borehole is planned to penetrate the main fault believed to lie in-between the holes. The main philosophy behind our approach for the hydrologic characterization of such a complex fractured system is to let the system take its own average and monitor a long term behavior instead of collecting a multitude of data at small length and time scales, or at a discrete fracture scale and to ?up-scale,? which is extremely tenuous.

  4. Application of three fault growth criteria to the Puente Hills thrust system, Los Angeles, California, USA

    Science.gov (United States)

    Olson, Erik L.; Cooke, Michele L.

    2005-10-01

    Three-dimensional mechanical models are used to evaluate the performance of different fault growth criteria in predicting successive growth of three échelon thrust faults similar to the segments of the Puente Hills thrust system of the Los Angeles basin, California. Four sequential Boundary Element Method models explore the growth of successive échelon faults within the system by simulating snapshots of deformation at different stages of development. These models use three criteria, (1) energy release rate, (2) strain energy density, and (3) Navier-Coulomb stress, to characterize the lateral growth of the fault system. We simulate the growth of an échelon thrust fault system to evaluate the suitability of each of these criteria for assessing fault growth. Each of these three factors predicts a portion of the incipient fault geometry (i.e. location or orientation); however, each provides different information. In each model, energy release rate along the westernmost (leading) tip of the Puente Hills thrust drops with growth of the next neighboring fault; this result supports the overall lateral development of successive échelon segments. Within each model, regions of high strain energy density and Navier-Coulomb stress envelope at least a portion of the next fault to develop, although the strain energy density has stronger correlation than Navier-Coulomb stress to the location of incipient faulting. In each model, one of the two predicted planes of maximum Navier-Coulomb stress ahead of the leading fault tip matches the strike but not the dip of the incipient fault plane recreating part of the fault orientation. The incipient fault dip is best predicted by the orientation of the strain energy density envelopes around the leading fault tip. Furthermore, the energy release rate and pattern of strain energy density can be used to characterize potential soft linkage (overlap) or hard linkage (connection) of échelon faults within the system.

  5. Fault Activity in the Terrebonne Trough, Southeastern Louisiana: A Continuation of Salt-Withdrawal Fault Activity from the Miocene into the late Quaternary and Implication for Subsidence Hot-Spots

    Science.gov (United States)

    Akintomide, A. O.; Dawers, N. H.

    2017-12-01

    The observed displacement along faults in southeastern Louisiana has raised questions about the kinematic history of faults during the Quaternary. The Terrebonne Trough, a Miocene salt withdrawal basin, is bounded by the Golden Meadow fault zone on its northern boundary; north dipping, so-called counter-regional faults, together with a subsurface salt ridge, define its southern boundary. To date, there are relatively few published studies on fault architecture and kinematics in the onshore area of southeastern Louisiana. The only publically accessible studies, based on 2d seismic reflection profiles, interpreted faults as mainly striking east-west. Our interpretation of a 3-D seismic reflection volume, located in the northwestern Terrebonne Trough, as well as industry well log correlations define a more complex and highly-segmented fault architecture. The northwest striking Lake Boudreaux fault bounds a marsh on the upthrown block from Lake Boudreaux on the downthrown block. To the east, east-west striking faults are located at the Montegut marsh break and north of Isle de Jean Charles. Portions of the Lake Boudreaux and Isle de Jean Charles faults serve as the northern boundary of the Madison Bay subsidence hot-spot. All three major faults extend to the top of the 3d seismic volume, which is inferred to image latest Pleistocene stratigraphy. Well log correlation using 11+ shallow markers across these faults and kinematic techniques such as stratigraphic expansion indices indicate that all three faults were active in the middle(?) and late Pleistocene. Based on expansion indices, both the Montegut and Isle de Jean Charles faults were active simultaneously at various times, but with different slip rates. There are also time intervals when the Lake Boudreaux fault was slipping at a faster rate compared to the east-west striking faults. Smaller faults near the margins of the 3d volume appear to relate to nearby salt stocks, Bully Camp and Lake Barre. Our work to date

  6. The pulsed migration of hydrocarbons across inactive faults

    Directory of Open Access Journals (Sweden)

    S. D. Harris

    1999-01-01

    Full Text Available Geological fault zones are usually assumed to influence hydrocarbon migration either as high permeability zones which allow enhanced along- or across-fault flow or as barriers to the flow. An additional important migration process inducing along- or across-fault migration can be associated with dynamic pressure gradients. Such pressure gradients can be created by earthquake activity and are suggested here to allow migration along or across inactive faults which 'feel' the quake-related pressure changes; i.e. the migration barriers can be removed on inactive faults when activity takes place on an adjacent fault. In other words, a seal is viewed as a temporary retardation barrier which leaks when a fault related fluid pressure event enhances the buoyancy force and allows the entry pressure to be exceeded. This is in contrast to the usual model where a seal leaks because an increase in hydrocarbon column height raises the buoyancy force above the entry pressure of the fault rock. Under the new model hydrocarbons may migrate across the inactive fault zone for some time period during the earthquake cycle. Numerical models of this process are presented to demonstrate the impact of this mechanism and its role in filling traps bounded by sealed faults.

  7. Kinematics of transition from subduction to strike-slip: an example from the New Zealand plate boundary (Invited)

    Science.gov (United States)

    Wallace, L. M.; Barnes, P.; Beavan, R. J.; van Dissen, R.; Pondard, N.; Litchfield, N. J.; Lamarche, G.; Little, T. A.

    2009-12-01

    We develop a kinematic model for the transition from oblique subduction beneath the North Island to strike-slip in the South Island, New Zealand, constrained by GPS velocities and onshore and new offshore active fault slip rate and location data. To interpret these data, we simultaneously invert the kinematic data for poles of rotation of tectonic blocks (block boundaries chosen to coincide with known active faults) and the degree of interseismic coupling on faults in the region, including the Hikurangi subduction thrust. Our best-fitting kinematic models require that the northeastern corner of the South Island undergoes significant vertical axis rotation as a part of the rapidly rotating (3-4°/Myr) North Island forearc block, while the remainder of the tectonic blocks in the South Island undergo negligible vertical axis rotation relative to the Pacific Plate. This result agrees well with clockwise paleomagnetic declinations from ~4 Ma rock samples in the northeastern South Island, and suggests that paleomagnetically-observed rotation of that region is continuing today. The poles of rotation between the more rapidly rotating northeastern South Island blocks and the non-rotating South Island blocks (further south) coincide with the boundary between the rotating and non-rotating domains of the South Island. This result is consistent with structural mapping of the rotation/non-rotation boundary by Little and Roberts (1997), and suggests that the transition from the rapidly rotating forearc of the Hikurangi subduction margin to a strike-slip dominated plate boundary in the South Island is accommodated by a crustal-scale kink or hinge in the upper plate of that subduction zone. This result highlights a remarkable consistency between datasets spanning decades (GPS), thousands of years (active fault data), and millions of years (paleomagnetic data and bedrock structure) in the northeastern South Island. Although the interseismic coupling coefficients that we estimate for

  8. Structural Design of Systems with Safe Behavior under Single and Multiple Faults

    DEFF Research Database (Denmark)

    Blanke, Mogens; Staroswiecki, Marcel

    2006-01-01

    Handling of multiple simultaneous faults is a complex issue in fault-tolerant control. The design task is particularly made difficult by to the numerous different cases that need be analyzed. Aiming at safe fault-handling, this paper shows how structural analysis can be applied to find...... the analytical redundancy relations for all relevant combinations of faults, and can cope with the complexity and size of a real system. Being essential for fault-tolerant control schemes that shall handle particular cases of faults/failures, fault isolation is addressed. The paper introduces an extension...... to structural analysis to disclose which faults could be isolated from a structural point of view using active fault isolation. Results from application on a marine control system illustrate the concepts....

  9. Architecture of buried reverse fault zone in the sedimentary basin: A case study from the Hong-Che Fault Zone of the Junggar Basin

    Science.gov (United States)

    Liu, Yin; Wu, Kongyou; Wang, Xi; Liu, Bo; Guo, Jianxun; Du, Yannan

    2017-12-01

    It is widely accepted that the faults can act as the conduits or the barrier for oil and gas migration. Years of studies suggested that the internal architecture of a fault zone is complicated and composed of distinct components with different physical features, which can highly influence the migration of oil and gas along the fault. The field observation is the most useful methods of observing the fault zone architecture, however, in the petroleum exploration, what should be concerned is the buried faults in the sedimentary basin. Meanwhile, most of the studies put more attention on the strike-slip or normal faults, but the architecture of the reverse faults attracts less attention. In order to solve these questions, the Hong-Che Fault Zone in the northwest margin of the Junggar Basin, Xinjiang Province, is chosen for an example. Combining with the seismic data, well logs and drill core data, we put forward a comprehensive method to recognize the internal architectures of buried faults. High-precision seismic data reflect that the fault zone shows up as a disturbed seismic reflection belt. Four types of well logs, which are sensitive to the fractures, and a comprehensive discriminated parameter, named fault zone index are used in identifying the fault zone architecture. Drill core provides a direct way to identify different components of the fault zone, the fault core is composed of breccia, gouge, and serpentinized or foliated fault rocks and the damage zone develops multiphase of fractures, which are usually cemented. Based on the recognition results, we found that there is an obvious positive relationship between the width of the fault zone and the displacement, and the power-law relationship also exists between the width of the fault core and damage zone. The width of the damage zone in the hanging wall is not apparently larger than that in the footwall in the reverse fault, showing different characteristics with the normal fault. This study provides a

  10. Bird strike incidence at Addis Ababa Bole International Airport ...

    African Journals Online (AJOL)

    The time and rate of bird strike incidences, species composition and number of birds involved in strikes, and the behaviour of birds were recorded at Bole International Airport from December 1994 to December 1995. The gut contents of the birds struck by aircraft were analyzed. A total of 33 bird strikes were recorded during ...

  11. 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

  12. effects of strike cost on economic development in nigeria

    African Journals Online (AJOL)

    USER

    productivity as in most cases strike cost (wages and salaries as well as other unavoidable payments) are paid during the .... Many times the Nigeria Labour Congress (NLC) and students have had to strike against ... the direct compensation package and other conditions of service. This is the most popular cause of strike in ...

  13. Modeling fluid flow in faulted basins

    International Nuclear Information System (INIS)

    Faille, I.; Thibaut, M.; Cacas, M.C.; Have, P.; Willien, F.; Wolf, S.; Agelas, L.; Pegaz-Fiornet, S.

    2014-01-01

    This paper presents a basin simulator designed to better take faults into account, either as conduits or as barriers to fluid flow. It computes hydrocarbon generation, fluid flow and heat transfer on the 4D (space and time) geometry obtained by 3D volume restoration. Contrary to classical basin simulators, this calculator does not require a structured mesh based on vertical pillars nor a multi-block structure associated to the fault network. The mesh follows the sediments during the evolution of the basin. It deforms continuously with respect to time to account for sedimentation, erosion, compaction and kinematic displacements. The simulation domain is structured in layers, in order to handle properly the corresponding heterogeneities and to follow the sedimentation processes (thickening of the layers). In each layer, the mesh is unstructured: it may include several types of cells such as tetrahedra, hexahedra, pyramid, prism, etc. However, a mesh composed mainly of hexahedra is preferred as they are well suited to the layered structure of the basin. Faults are handled as internal boundaries across which the mesh is non-matching. Different models are proposed for fault behavior such as impervious fault, flow across fault or conductive fault. The calculator is based on a cell centered Finite Volume discretization, which ensures conservation of physical quantities (mass of fluid, heat) at a discrete level and which accounts properly for heterogeneities. The numerical scheme handles the non matching meshes and guaranties appropriate connection of cells across faults. Results on a synthetic basin demonstrate the capabilities of this new simulator. (authors)

  14. Paleoseismology of the 1966 Varto Earthquake (Ms 6.8) and Structure of the Varto Fault Zone, Eastern Turkey

    Science.gov (United States)

    Isik, V.; Caglayan, A.; Saber, R.; Yesilyurt, N.

    2014-12-01

    Turkey is a region of active faulting and contains several strike-slip fault zones, which have generated both historical and recent large earthquakes. Two active fault zones in Turkey, the North Anatolian Fault Zone (NAFZ) and the East Anatolian Fault Zone (EAFZ), divide the area into the Anatolian micro-plate accommodating WSW-directed movement. The southeastern continuation of the NAFZ is often referred to the Varto Fault Zone (VFZ). The VFZ cuts mainly Pliocene volcano-sedimentary units and/or Quaternary deposits and is characterized by multiple fault strands and multiple, closely spaced, active seismogenic zones. Fault motions in the zone are primarily right-lateral, with a subordinate component of NNW-SSE shortening. Study area is Varto region in which indications of active faulting are very well preserved. We recognized three coseismic ruptures from five trench exposures. It is referred to these as events 1 (youngest) through 3 (oldest). The best evidence of event 3 comes from fault traces and its upward terminations. The major components of this fault are fault core and damage zone. The fault is not just one plane of discontinuity and bifurcates and creates additional slip surfaces, which propagate out of the plane of the original fault. Event 2 and event 1, referring to 1946 and 1966 earthquakes, are characterized primarily by discrete, regularly spaced normal faults with and 55-80 cm and 105-270 cm throws, respectively and geometry of growth strata. The VFZ in the study area include typical structures of strike-slip fault zone. It forms a number of parallel and slightly sub-parallel strands striking N50°-72°W including contractional and extensional brittle structures. Several meters to tens of meters wavelength active folds with ENE-WSW and WNW-ESE trending fold axis. These folds deform the Plio-Quaternary units and show classic asymmetry associated with both a south- and north-vergent fault propagation fold. Meso-scale normal faults are also well

  15. Simulation of Co-Seismic Off-Fault Stress Effects: Influence of Fault Roughness and Pore Pressure Coupling

    Science.gov (United States)

    Fälth, B.; Lund, B.; Hökmark, H.

    2017-12-01

    Aiming at improved safety assessment of geological nuclear waste repositories, we use dynamic 3D earthquake simulations to estimate the potential for co-seismic off-fault distributed fracture slip. Our model comprises a 12.5 x 8.5 km strike-slip fault embedded in a full space continuum where we apply a homogeneous initial stress field. In the reference case (Case 1) the fault is planar and oriented optimally for slip, given the assumed stress field. To examine the potential impact of fault roughness, we also study cases where the fault surface has undulations with self-similar fractal properties. In both the planar and the undulated cases the fault has homogeneous frictional properties. In a set of ten rough fault models (Case 2), the fault friction is equal to that of Case 1, meaning that these models generate lower seismic moments than Case 1. In another set of ten rough fault models (Case 3), the fault dynamic friction is adjusted such that seismic moments on par with that of Case 1 are generated. For the propagation of the earthquake rupture we adopt the linear slip-weakening law and obtain Mw 6.4 in Case 1 and Case 3, and Mw 6.3 in Case 2 (35 % lower moment than Case 1). During rupture we monitor the off-fault stress evolution along the fault plane at 250 m distance and calculate the corresponding evolution of the Coulomb Failure Stress (CFS) on optimally oriented hypothetical fracture planes. For the stress-pore pressure coupling, we assume Skempton's coefficient B = 0.5 as a base case value, but also examine the sensitivity to variations of B. We observe the following: (I) The CFS values, and thus the potential for fracture slip, tend to increase with the distance from the hypocenter. This is in accordance with results by other authors. (II) The highest CFS values are generated by quasi-static stress concentrations around fault edges and around large scale fault bends, where we obtain values of the order of 10 MPa. (III) Locally, fault roughness may have a

  16. Miocene Tectonics at the Pannonian - Carpathian Transition: The Bogdan Voda - Dragos Voda fault system, northern Romania

    Science.gov (United States)

    Tischler, M.; Gröger, H.; Marin, M.; Schmid, S. M.; Fügenschuh, B.

    2003-04-01

    Tertiary tectonics in the Pannonian-Carpathian transition zone was dominated by opposed rotations of Alcapa and Tisza-Dacia, separated by the Mid-Hungarian lineament (MHL). While in the Pannonian basin the MHL is well known from geophysical and borehole data, its northeastern continuation remains a matter of discussion. Our field based study, located in the Maramures mountains of northern Romania, provides new kinematic data from the Bogdan Voda fault, a first order candidate for the prolongation of the MHL to the northeast. In the Burdigalian, the Pienides (unmetamorphic flysch nappes) were emplaced onto the autochthonous Paleogene flysch units. Kinematic data consistently indicate top to the SE-directed thrusting of the Pienides and selected imbrications in the autochthonous units. Between Langhian and Tortonian these thrust contacts were offset by the E-W trending Bogdan Voda fault and its eastern continuation, the Dragos-Voda fault. These two faults share a common polyphase history, at least since the Burdigalian. Kinematic data derived from mesoscale faults indicate sinistral strike-slip displacement, in good agreement with kinematics inferred from map view. The NE-SW trending Greben fault, another fault of regional importance, was coevally active as a normal fault. From stratigraphic arguments major activity of this fault system is constrained to the time interval between 16.4-10 Ma. While deformation is strongly concentrated in the sedimentary units, the easterly located basement units are affected by abundant minor faults of similar kinematics covering a wide area. These SW-NE trending strike slip faults feature a normal component and resemble an imbricate fan geometry. Since Burdigalian thrusting is consistently SE-directed on either side of the Bogdan-Dragos Voda fault, major post-Burdigalian differential rotations can be excluded for the northern and southern block respectively. Hydrothermal veins within Pannonian volcanic units are aligned along the

  17. Constraints from Mesozoic siliciclastic cover rocks and satellite image analysis on the slip history of regional E-W faults in the southeast Western Desert, Egypt

    Science.gov (United States)

    Tewksbury, Barbara J.; Mehrtens, Charlotte J.; Gohlke, Steven A.; Tarabees, Elhamy A.; Hogan, John P.

    2017-12-01

    In the southeast Western Desert of Egypt, a prominent set of E-W faults and co-located domes and basins involve sedimentary cover rock as young as the early Eocene. Although earlier Mesozoic slip on faults in southern Egypt has been widely mentioned in the literature and attributed to repeated reactivation of basement faults, evidence is indirect and based on the idea that regional stresses associated with tectonic events in the Syrian Arc would likely have reactivated basement faults in south Egypt in dextral strike slip during the Mesozoic as well as the Cenozoic. Here, we present direct evidence from the rock record for the sequence of development of features along these faults. Southwest of Aswan, a small structural dome in Mesozoic Nubia facies rocks occurs where the Seiyal Fault bends northward from west to east. The dome is cut by strands of the Seiyal Fault and a related set of cataclastic deformation bands showing dominantly right lateral strike slip, as well as by younger calcite veins with related patchy poikilotopic cement. High resolution satellite image analysis of the remote southwest Kharga Valley shows a similar sequence of events: older structural domes and basins located where E-W faults bend northward from west to east, right lateral offset of domes and basins along the E-W faults, and two sets of deformation band faults that lack co-located domes and basins. We suggest that field data, image analysis, and burial depth estimates are best explained by diachronous development of features along the E-W fault system. We propose that Late Mesozoic right lateral strike slip produced domes and basins in Nubia facies rocks in stepover regions above reactivated basement faults. We further suggest that the extensively linked segments of the E-W fault system in Nubia facies rocks, plus the deformation band systems, formed during the late Eocene when basement faults were again reactivated in dominantly right lateral strike slip.

  18. 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.

  19. Faults in Linux 2.6

    OpenAIRE

    Palix , Nicolas; Thomas , Gaël; Saha , Suman; Calvès , Christophe; Muller , Gilles; Lawall , Julia L.

    2014-01-01

    International audience; In August 2011, Linux entered its third decade. Ten years before, Chou et al. published a study of faults found by applying a static analyzer to Linux versions 1.0 through 2.4.1. A major result of their work was that the drivers directory contained up to 7 times more of certain kinds of faults than other directories. This result inspired numerous efforts on improving the reliability of driver code. Today, Linux is used in a wider range of environments, provides a wider...

  20. Neuroadaptive Fault-Tolerant Control of Nonlinear Systems Under Output Constraints and Actuation Faults.

    Science.gov (United States)

    Zhao, Kai; Song, Yongduan; Shen, Zhixi

    2018-02-01

    In this paper, a neuroadaptive fault-tolerant tracking control method is proposed for a class of time-delay pure-feedback systems in the presence of external disturbances and actuation faults. The proposed controller can achieve prescribed transient and steady-state performance, despite uncertain time delays and output constraints as well as actuation faults. By combining a tangent barrier Lyapunov-Krasovskii function with the dynamic surface control technique, the neural network unit in the developed control scheme is able to take its action from the very beginning and play its learning/approximating role safely during the entire system operational envelope, leading to enhanced control performance without the danger of violating compact set precondition. Furthermore, prescribed transient performance and output constraints are strictly ensured in the presence of nonaffine uncertainties, external disturbances, and undetectable actuation faults. The control strategy is also validated by numerical simulation.

  1. A Pyrenean Cretaceous extensional fault system in the Briançonnais Domain of the Alps: implications for the eastern termination of the segmented Bay of Biscay-Pyrenean rift system.

    Science.gov (United States)

    Tavani, Stefano; Bertok, Carlo; D'Atri, Anna; Piana, Fabrizio; Barale, Luca; Corradetti, Amerigo; Granado, Pablo; Martire, Luca; Vigna, Bartolomeo

    2017-04-01

    Recent studies in the foreland fold and thrust belt of the SW Alps reported that, in spite of the obliterating effect by the Alpine deformation, Mesozoic structures can still be recognised. These structures, occurring at the southern portion of the Western Alps arc, include a well-exposed crustal-scale Cretaceous extensional fault system. Field data (geological maps) and subsurface data (karst network) have been integrated to produce a detailed 3D reconstruction of this extensional fault system. Cretaceous faults affect the Paleozoic and Mesozoic successions and consist of a tens of km long E-W striking master fault, having in its northern block a set of E-dipping transverse extensional faults, having displacements in the order of hundreds of meters. The 3D reconstruction indicates that E-W extension, accommodated by transverse faults, is between 20% and 40%, and it reduces toward the E-W striking master fault. N-S extension is instead negligible and the E-W fault is interpreted as a Cretaceous right-lateral strike-slip fault. Removing the about 120° counter-clockwise vertical axis rotation, which is associated with the post-Cretaceous Alpine orogeny, the strike-slip fault becomes parallel to a suite of NNE-SSW to NE-SW striking faults occurring in the SW Alps foreland (present Provence region). We propose that, during the Cretaceous separation of Iberia from Eurasia, the NNE-SSW striking faults of Provence and Western Alps were delimiting to the east the Bay of Biscay - Pyrenean rift system. In detail, they formed a NNE-SSW striking transfer zone bounding to the east the Pyrenean arm of the rift, and likely ensured the connection of the Bay of Biscay - Pyrenean rift system with a further eastern, intra-plate, arm.

  2. Reactivation of normal faults as high-angle reverse faults due to low frictional strength: Experimental data from the Moonlight Fault Zone, New Zealand

    Science.gov (United States)

    Smith, S. A. F.; Tesei, T.; Scott, J. M.; Collettini, C.

    2017-12-01

    Large normal faults are frequently reactivated as high-angle reverse faults during basin inversion. Elevated fluid pressure is commonly invoked to explain high-angle reverse slip. Analogue and numerical modeling have demonstrated that frictional weakening may also promote high-angle reverse slip, but there are currently no frictional strength measurements available for fault rocks collected from large high-angle reverse faults. To test the hypothesis that frictional weakening could facilitate high-angle reverse slip, we performed single- and double-direct friction experiments on fault rocks collected from the Moonlight Fault Zone in New Zealand, a basin-bounding normal fault zone that was reactivated as a high-angle reverse fault (present-day dip angle 60°-75°). The fault core is exposed in quartzofeldspathic schists exhumed from c. 4-8 km depth and contains a <20 m thick sequence of breccias, cataclasites and foliated cataclasites that are enriched in chlorite and muscovite. Friction experiments on water-saturated, intact samples of foliated cataclasite at room temperature and normal stresses up to 75 MPa yielded friction coefficients of 0.19<μ < 0.25. On the assumption of horizontal maximum compressive stress, reactivation analysis indicates that a friction coefficient of <0.25 will permit slip on high-angle reverse faults at hydrostatic (or even sub-hydrostatic) fluid pressures. Since foliated and phyllosilicate-rich fault rocks are common in large reactivated fault zones at basement depths, long-term frictional weakening is likely to act in concert with episodic build-ups of fluid pressure to promote high-angle reverse slip during basin inversion.

  3. 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 ...

  4. FOP 2012 stop, Honey Lake fault, Doyle, CA

    Science.gov (United States)

    Gold, Ryan; Briggs, Richard W.; Crone, Anthony; Angster, Steve; Seitz, Gordon G.

    2012-01-01

    The Honey Lake fault system (HLFS) strikes north-northwestward across Long Valley near Doyle, CA and is part of a network of active, dextral strike-slip faults in the northern Walker Lane (Figure 1). Geologic investigations of a right-laterally offset terrace riser along the north bank of Long Valley Creek, which we refer to as site 1 (Figure 2), indicate a latest Quaternary slip rate of 1.1-2. 6 mm/yr [Wills and Borchardt, 1993] and 1.7 ± 0.6 mm/yr [Turner and others, 2008] (Table 1). These studies also document evidence of at least four post-6.8 ka surface-rupturing earthquakes at this site.

  5. Uncovering dynamic fault trees

    NARCIS (Netherlands)

    Junges, Sebastian; Guck, Dennis; Katoen, Joost P.; Stoelinga, Mariëlle Ida Antoinette

    Fault tree analysis is a widespread industry standard for assessing system reliability. Standard (static) fault trees model the failure behaviour of systems in dependence of their component failures. To overcome their limited expressive power, common dependability patterns, such as spare management,

  6. Strike Point Control for the National Spherical Torus Experiment (NSTX)

    International Nuclear Information System (INIS)

    Kolemen, E.; Gates, D.A.; Rowley, C.W.; Kasdin, N.J.; Kallman, J.; Gerhardt, S.; Soukhanovskii, V.; Mueller, D.

    2010-01-01

    This paper presents the first control algorithm for the inner and outer strike point position for a Spherical Torus (ST) fusion experiment and the performance analysis of the controller. A liquid lithium divertor (LLD) will be installed on NSTX which is believed to provide better pumping than lithium coatings on carbon PFCs. The shape of the plasma dictates the pumping rate of the lithium by channeling the plasma to LLD, where strike point location is the most important shape parameter. Simulations show that the density reduction depends on the proximity of strike point to LLD. Experiments were performed to study the dynamics of the strike point, design a new controller to change the location of the strike point to desired location and stabilize it. The most effective PF coils in changing inner and outer strike points were identified using equilibrium code. The PF coil inputs were changed in a step fashion between various set points and the step response of the strike point position was obtained. From the analysis of the step responses, PID controllers for the strike points were obtained and the controller was tuned experimentally for better performance. The strike controller was extended to include the outer-strike point on the inner plate to accommodate the desired low outer-strike points for the experiment with the aim of achieving 'snowflake' divertor configuration in NSTX.

  7. Solar system fault detection

    Science.gov (United States)

    Farrington, R.B.; Pruett, J.C. Jr.

    1984-05-14

    A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combining the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.

  8. Fault Tolerant Control Systems

    DEFF Research Database (Denmark)

    Bøgh, S. A.

    This thesis considered the development of fault tolerant control systems. The focus was on the category of automated processes that do not necessarily comprise a high number of identical sensors and actuators to maintain safe operation, but still have a potential for improving immunity to component...... failures. It is often feasible to increase availability for these control loops by designing the control system to perform on-line detection and reconfiguration in case of faults before the safety system makes a close-down of the process. A general development methodology is given in the thesis...... that carried the control system designer through the steps necessary to consider fault handling in an early design phase. It was shown how an existing control loop with interface to the plant wide control system could be extended with three additional modules to obtain fault tolerance: Fault detection...

  9. Offshore extension of the Great Sumatra Fault revealed by seismic, bathymetric and seafloor imaging

    Science.gov (United States)

    Gaedicke, C.; Soh, W.; Djajadihardja, Y.; Saito, S.; Ikeda, Y.; Kudrass, H.; Djamaluddin, R.

    2003-12-01

    The northwestern Sunda Arc is cut by two giant dextral shear zones, which accommodate the oblique subduction of the Indo-Australian Plate against Eurasia along this portion of the Sunda Arc. These are the Sumatra Fault Zone on Sumatra Island and the Mentawai Fault Zone off west Sumatra. The strike-slip shear zones bear a high earthquake risk potential. Several Indonesian-Japanese-German marine expeditions focused on the tectonics and the evolution of the Sumatra and Java forearc region. Now a dense grid of multi- and single-channel reflection seismic profiles, high resolution bathymetry and seafloor direct observations using submersible SHINKAI 6500 allow tracing the Sumatra and Mentawai Fault Zones south off west Java. The geometry of transtensional basins, transpressional horst structures and elongated ridges and valleys clearly shows the dextral sense of motion and the splay character of the fault zones in the study area. Multi-channel reflection profiles image the deep structure of the major strike slip faults which originate from reactivated thrust planes within the Java accretionary wedge. During SHINKAI 6500 dives one master fault could be followed. Recent offset along the fault is documented on sea floor images by young unweathered fault scarps.

  10. Fault plane solutions of the January 26th, 2001 Bhuj earthquake ...

    Indian Academy of Sciences (India)

    Fault-plane solutions of the best- located and selected cluster of events that occurred along the NE trend, at a depth of 15-38 km, show reverse faulting with a large left-lateral strike-slip motion, which are comparable with the main-shock solution. The NW trending upper crustal aftershocks at depth < 10 km, on the other hand ...

  11. 3D Dynamic Rupture Simulations Across Interacting Faults: the Mw7.0, 2010, Haiti Earthquake

    Science.gov (United States)

    Douilly, R.; Aochi, H.; Calais, E.; Freed, A. M.; Aagaard, B.

    2014-12-01

    The mechanisms controlling rupture propagation between fault segments during an earthquake are key to the hazard posed by fault systems. Rupture initiation on a fault segment sometimes transfers to a larger fault, resulting in a significant event (e.g.i, 2002 M7.9Denali and 2010 M7.1 Darfield earthquakes). In other cases rupture is constrained to the initial segment and does not transfer to nearby faults, resulting in events of moderate magnitude. This is the case of the 1989 M6.9 Loma Prieta and 2010 M7.0 Haiti earthquakes which initiated on reverse faults abutting against a major strike-slip plate boundary fault but did not propagate onto it. Here we investigatethe rupture dynamics of the Haiti earthquake, seeking to understand why rupture propagated across two segments of the Léogâne fault but did not propagate to the adjacenent Enriquillo Plantain Garden Fault, the major 200 km long plate boundary fault cutting through southern Haiti. We use a Finite Element Model to simulate the nucleation and propagation of rupture on the Léogâne fault, v