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Sample records for plate boundary deformation

  1. What drives microplate motion and deformation in the northeastern Caribbean plate boundary region?

    NARCIS (Netherlands)

    van Benthem, S.A.C.|info:eu-repo/dai/nl/304833657; Govers, R.|info:eu-repo/dai/nl/108173836; Wortel, R.|info:eu-repo/dai/nl/068439202

    2014-01-01

    The north Caribbean plate boundary zone is a broad deformation zone with several fault systems and tectonic blocks that move with different velocities. The indentation by the Bahamas Platform (the “Bahamas Collision”) is generally invoked as a cause of this fragmentation. We propose that a second

  2. What drives microplate motion and deformation in the northeastern Caribbean plate boundary region?

    NARCIS (Netherlands)

    van Benthem, S.A.C.|info:eu-repo/dai/nl/304833657; Govers, R.|info:eu-repo/dai/nl/108173836; Wortel, R.|info:eu-repo/dai/nl/068439202

    2014-01-01

    The north Caribbean plate boundary zone is a broad deformation zone with several fault systems and tectonic blocks that move with different velocities. The indentation by the Bahamas Platform (the “Bahamas Collision”) is generally invoked as a cause of this fragmentation. We propose that a second dr

  3. Cocos Ridge Collision as a Driver for Plate Boundary Deformation in the Western Caribbean

    Science.gov (United States)

    La Femina, P. C.; Govers, R. M.; Geirsson, H.; Kobayashi, D.

    2011-12-01

    The subduction and collision of bathymetric highs can result in geodynamic changes along convergent plate boundaries, including intense upper plate deformation, increases in mechanical coupling and seismicity, migration and or cessation of volcanism and formation of forearc terranes. But how extensive can the deformation associated with these features be and what are the implications for the long-term formation and evolution of plate boundary zones? Plate boundary evolution and upper plate deformation in southern Central America associated with Cocos Ridge collision is well studied and indicates, 1) migration of the volcanic arc toward the backarc northwest of and cessation of volcanism directly inboard the ridge, 2) uplift of the Cordillera de Talamanca inboard the ridge, 3) shortening across the forearc Fila Costena fold and thrust belt, and 4) outer forearc uplift above and flanking the ridge. Recent geodynamical modeling of Cocos Ridge collision, combined with the results of kinematic block models for the Central American margin, suggests the ridge drives northwest-directed forearc motion from central Costa Rica northwest to the Cocos - Caribbean (Central American forearc block) - North America triple junction, greatly increasing the spatial scale of deformation. Upperplate deformation of the Central American margin to the southeast of the Cocos Ridge in Panama was not investigated in these models. We investigate the dynamics of Cocos Ridge collision along the entire Central American margin and the implications on plate boundary evolution with a new geodynamic model of ridge collision. Our model results are compared to a new GPS derived horizontal velocity field for Central America and preliminary results indicate that the Cocos Ridge drives the Panamanian isthmus into northern South America (i.e., the North Andes block).

  4. Distributed Plate Boundary Deformation Across the San Andreas Fault System, Central California

    Science.gov (United States)

    Dyson, M.; Titus, S. J.; Demets, C.; Tikoff, B.

    2007-12-01

    Plate boundaries are now recognized as broad zones of complex deformation as opposed to narrow zones with discrete offsets. When assessing how plate boundary deformation is accommodated, both spatially and temporally, it is therefore crucial to understand the relative contribution of the discrete and distributed components of deformation. The creeping segment of the San Andreas fault is an ideal location to study the distribution of plate boundary deformation for several reasons. First, the geometry of the fault system in central California is relatively simple. Plate motion is dominated by slip along the relatively linear strike-slip San Andreas fault, but also includes lesser slip along the adjacent and parallel Hosgri-San Gregorio and Rinconada faults, as well as within the borderlands between the three fault strands. Second, the aseismic character of the San Andreas fault in this region allows for the application of modern geodetic techniques to assess creep rates along the fault and across the region. Third, geologic structures within the borderlands are relatively well-preserved allowing comparison between modern and ancient rates and styles of deformation. Continuous GPS stations, alignment arrays surveys, and other geodetic methods demonstrate that approximately 5 mm/yr of distributed slip is accumulated (on top of the fault slip rate) across a 70-100 km wide region centered on the San Andreas fault. New campaign GPS data also suggest 2-5 mm/yr of deformation in the borderlands. These rates depend on the magnitude of the coseismic and postseismic corrections that must be made to our GPS time series to compensate for the 2003 San Simeon and 2004 Parkfield earthquakes, which rupture faults outside, but near the edges of our GPS network. The off-fault deformation pattern can be compared to the style of permanent deformation recorded in the geologic record. Fold and thrust belts in the borderlands are better developed in the Tertiary sedimentary rocks west of

  5. Plate boundary deformation at the latitude of the Salton Trough - northern Gulf of California (Invited)

    Science.gov (United States)

    Stock, J. M.

    2013-12-01

    Along the Pacific-North America plate boundary zone, the segment including the southern San Andreas fault to Salton Trough and northern Gulf of California basins has been transtensional throughout its evolution, based on Pacific-North America displacement vectors calculated from the global plate circuit (900 × 20 km at N54°W since 20 Ma; 460 × 20 km at N48°W since 11 Ma). Nevertheless, active seismicity and focal mechanisms show a broad zone of plate boundary deformation within which the inferred stress regime varies locally (Yang & Hauksson 2013 GJI), and fault patterns in some regions suggest ongoing tectonic rotation. Similar behavior is inferred to have occurred in this zone over most of its history. Crustal structure in this region is constrained by surface geology, geophysical experiments (e.g., the 2011 Salton Seismic Imaging Project (SSIP), USGS Imperial Valley 1979, PACE), and interdisciplinary marine and onland studies in Mexico (e.g., NARS-Baja, Cortes, and surveys by PEMEX). Magnetic data (e.g., EMAG-2) aids in the recognition of large-scale crustal provinces and fault boundaries in regions lacking detailed geophysical surveys. Consideration of existing constraints on crustal thickness and architecture, and fault and basin evolution suggests that to reconcile geological deformation with plate motion history, the following additional factors need to be taken into account. 1) Plate boundary displacement via interacting systems of rotating blocks, coeval with slip on steep strike slip faults, and possibly related to slip on low angle extensional faults (e.g, Axen & Fletcher 1998 IGR) may be typical prior to the onset of seafloor spreading. This fault style may have accommodated up to 150 km of plate motion in the Mexican Continental Borderland and north of the Vizcaino Peninsula, likely between 12 and 15 Ma, as well as explaining younger rotations adjacent to the Gulf of California and current deformation southwest of the Salton Sea. 2) Geophysical

  6. Obliquity along plate boundaries

    Science.gov (United States)

    Philippon, Mélody; Corti, Giacomo

    2016-12-01

    Most of the plate boundaries are activated obliquely with respect to the direction of far field stresses, as roughly only 8% of the plate boundaries total length shows a very low obliquity (ranging from 0 to 10°, sub-orthogonal to the plate displacement). The obliquity along plate boundaries is controlled by (i) lateral rheological variations within the lithosphere and (ii) consistency with the global plate circuit. Indeed, plate tectonics and magmatism drive rheological changes within the lithosphere and consequently influence strain localization. Geodynamical evolution controls large-scale mantle convection and plate formation, consumption, and re-organization, thus triggering plate kinematics variations, and the adjustment and re-orientation of far field stresses. These geological processes may thus result in plate boundaries that are not perpendicular but oblique to the direction of far field stresses. This paper reviews the global patterns of obliquity along plate boundaries. Using GPlate, we provide a statistical analysis of present-day obliquity along plate boundaries. Within this framework, by comparing natural examples and geological models, we discuss deformation patterns and kinematics recorded along oblique plate boundaries.

  7. Modeling the Philippine Mobile Belt: Tectonic blocks in a deforming plate boundary zone

    Science.gov (United States)

    Galgana, G. A.; Hamburger, M. W.; McCaffrey, R.; Bacolcol, T. C.; Aurelio, M. A.

    2007-12-01

    The Philippine Mobile Belt, a seismically active, rapidly deforming plate boundary zone situated along the convergent Philippine Sea/Eurasian plate boundary, is examined using geodetic and seismological data. Oblique convergence between the Philippine Sea Plate and the Eurasian plate is accommodated by nearly orthogonal subduction along the Philippine Trench and the Manila Trench, as well as by strike-slip faulting along the Philippine Fault system. We develop a model of active plate boundary deformation in this region, using elastic block models constrained by known fault geometries, published GPS observations and focal mechanism solutions. We then present an estimate of block rotations, fault coupling, and intra-block deformation, based on the best-fit model that minimizes the misfit between observed and predicted geodetic vectors and earthquake slip vectors. Slip rates along the Philippine fault vary from ~22 - 36 mm/yr in the Central Visayas and about 10 to 40 mm/yr in Luzon, trending almost parallel to the fault trace. In northern Luzon, Philippine Fault splays accommodate transpressional strain. The Central Visayas block experiences convergence with the Sundaland block along the Negros Trench and the Mindoro-Palawan collision zone. On the eastern side of Central Visayas, sinistral strike-slip faulting occurs along the NNW-SSE-trending Philippine Fault. Mindanao Island in southern Philippines is dominated by east-verging subduction along the Cotabato Trench, and strain partitioning (strike- slip faulting with west-verging subduction) in eastern Mindanao along the southern Philippine Fault and Philippine Trench, respectively. Oblique active sinistral strike slip faults in Central and Eastern Mindanao that were hypothesized to be responsible for basin formation are obvious boundaries for tectonic blocks. Located south of Mindanao Island we define an adjoining oceanic block defined by the N-S trending complex dual subduction zone of Sangihe and Halmahera

  8. New GPS constraints on active deformation along the Africa-Iberia plate boundary

    Science.gov (United States)

    Koulali, A.; Ouazar, D.; Tahayt, A.; King, R. W.; Vernant, P.; Reilinger, R. E.; McClusky, S.; Mourabit, T.; Davila, J. M.; Amraoui, N.

    2011-08-01

    We use velocities from 65 continuous stations and 31 survey-mode GPS sites as well as kinematic modeling to investigate present day deformation along the Africa-Iberia plate boundary zone in the western Mediterranean region. The GPS velocity field shows southwestward motion of the central part of the Rif Mountains in northern Morocco with respect to Africa varying between 3.5 and 4.0 mm/yr, consistent with prior published results. Stations in the southwestern part of the Betic Mountains of southern Spain move west-southwest with respect to Eurasia (˜ 2-3 mm/yr). The western component of Betics motion is consistent with partial transfer of Nubia-Eurasia plate motion into the southern Betics. The southward component of Betics motion with respect to Iberia is kinematically consistent with south to southwest motion of the Rif Mountains with respect to Africa. We use block modeling, constrained by mapped surface faults and seismicity to estimate the geometry and rates of strain accumulation on plate boundary structures. Our preferred plate boundary geometry includes one block between Iberia and Africa including the SW Betics, Alboran Sea, and central Rif. This geometry provides a good fit to the observed motions, suggesting a wide transpressive boundary in the westernmost Mediterranean, with deformation mainly accommodated by the Gloria-Azores fault system to the West and the Rif-Tell lineament to the East. Block boundaries encompass aspects of earlier interpretations suggesting three main deformation styles: (i) extension along the NE-SW trending Trans-Alboran shear zone, (ii) dextral strike-slip in the Betics corresponding to a well defined E-W seismic lineament, and (iii) right lateral strike-slip motion extending West to the Azores and right-lateral motion with compression extending East along the Algerian Tell. We interpret differential motion in the Rif-Alboran-Betic system to be driven both by surface processes related the Africa-Eurasia oblique convergence and

  9. Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula, Iceland

    KAUST Repository

    Keiding, Marie

    2010-07-01

    We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992-1999 and 2003-2008 as well as GPS data from 2000-2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10. cm is observed during the first 2. years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction. © 2010 Elsevier B.V.

  10. Lithospheric deformation in the Africa-Iberia plate boundary: Improved neotectonic modeling testing a basal-driven Alboran plate

    Science.gov (United States)

    Neres, M.; Carafa, M. M. C.; Fernandes, R. M. S.; Matias, L.; Duarte, J. C.; Barba, S.; Terrinha, P.

    2016-09-01

    We present an improved neotectonic numerical model of the complex NW Africa-SW Eurasia plate boundary segment that runs from west to east along the Gloria Fault up to the northern Algerian margin. We model the surface velocity field and the ongoing lithospheric deformation using the most recent version of the thin-shell code SHELLS and updated lithospheric model and fault map of the region. To check the presence versus the absence of an independently driven Alboran domain, we develop two alternative plate models: one does not include an Alboran plate; another includes it and determines the basal shear tractions necessary to drive it with known velocities. We also compare two alternative sets of Africa-Eurasia velocity boundary conditions, corresponding to geodetic and geological-scale averages of plate motion. Finally, we perform an extensive parametric study of fault friction coefficient, trench resistance, and velocities imposed in Alboran nodes. The final run comprises 5240 experiments, each scored to geodetic velocities (estimated for 250 stations and here provided), stress direction data, and seismic strain rates. The model with the least discrepancy to the data includes the Alboran plate driven by a basal WSW directed shear traction, slightly oblique to the westward direction of Alboran motion. We provide estimates of long-term strain rates and slip rates for the modeled faults, which can be useful for further hazard studies. Our results support that a mechanism additional to the Africa-Eurasia convergence is required to drive the Alboran domain, which can be related to subduction processes occurring within the mantle.

  11. Lower plate deformation structures along the Costa Rica erosive plate boundary - results from IODP Expedition 344 (CRISP 2)

    Science.gov (United States)

    Brandstätter, Jennifer; Kurz, Walter; Micheuz, Peter; Krenn, Kurt

    2015-04-01

    1414 is located ~1 km seaward of the deformation front offshore the Osa Peninsula and Caño Island. Primary science goals at Site U1414 included characterization of the alteration state of the magmatic basement. Brittle structures within the incoming plate (sites U1380, U1414) are mineralized extensional fractures and shear fractures. The shear fractures mainly show a normal component of shear. Within the sedimentary sequence both types of fractures dip steeply (vertical to subvertical) and strike NNE-SSW. Deformation bands trend roughly ENE-WSW, sub-parallel to the trend of the Cocos ridge. Structures in the Cocos Ridge basalt mainly comprise mineralized veins at various orientations. A preferred orientation of strike directions was not observed. Some veins show straight boundaries, others are characterized by an irregular geometry characterized by brecciated wall rock clasts embedded within vein precipitates. The vein mineralization was analysed in detail by RAMAN spectroscopy. Precipitation conditions and fluid chemistry were analysed by fluid inclusions entrapped within vein minerals. Vein mineralizations mainly consist of carbonate (fibrous aragonite, calcite), chalcedony, and quartz. Vein mineralization is mainly characterized by zoned antitaxial growth of carbonate fibres including a suture along the central vein domains. Quartz is often characterized by fibre growth of crystals perpendicular to the vein boundaries, too. These zoned veins additinally have wall rock alteration seams consisting of clay minerals. The precipitation sequence basically indicates that fluid chemistry evolved from an CO2-rich towards a SiO2- rich fluid.

  12. Strength and Deformation Rate of Plate Boundaries: The Rheological Effects of Grain Size Reduction, Structure, and Serpentinization.

    Science.gov (United States)

    Montesi, L.; Gueydan, F.

    2016-12-01

    Global strain rate maps reveal 1000-fold contrasts between plate interiors, oceanic or continental diffuse plate boundaries and narrow plate boundaries. Here, we show that rheological models based on the concepts of shear zone localization and the evolution of rock structure upon strain can explain these strain rate contrasts. Ductile shear zones constitute a mechanical paradox in the lithosphere. As every plastic deformation mechanism is strain-rate-hardening, ductile rocks are expected to deform at low strain rate and low stress (broad zone of deformation). Localized ductile shear zones require either a localized forcing (locally high stress) or a thermal or structural anomaly in the shear zone; either can be inherited or develop progressively as rocks deform. We previously identified the most effective process at each depth level of the lithosphere. In the upper crust and middle crust, rocks fabric controls localization. Grain size reduction is the most efficient mechanism in the uppermost mantle. This analysis can be generalized to consider a complete lithospheric section. We assume strain rate does not vary with depth and that the depth-integrated strength of the lithospheric does not change over time, as the total force is controlled by external process such as mantle convection and plate and slab buoyancy. Reducing grain size from a coarse value typical of undeformed peridotite to a value in agreement with the stress level (piezometer) while letting that stress vary from depth to depth (the integrated stress remains the same) increases the lithospheric strain rate by about a factor of 1000. This can explain the development of diffuse plate boundaries. The slightly higher strain rate of continental plate boundary may reflect development of a layered rock fabric in the middle crust. Narrow plate boundaries require additional weakening process. The high heat flux near mid-ocean ridge implies a thin lithosphere, which enhances stress (for constant integrated

  13. Paleomagnetic constraints on Cenozoic deformation along the northwest margin of the Pacific-Australian plate boundary zone through New Zealand

    Science.gov (United States)

    Turner, Gillian M.; Michalk, Daniel M.; Little, Timothy A.

    2012-02-01

    New Zealand straddles the boundary between the Australian and Pacific plates, a zone of oblique continental convergence and transform motion. The actively deforming region offers a unique opportunity to study the dynamics of deformation, including vertical-axis rotation of rigid blocks within a transcurrent plate boundary zone. We present and interpret paleomagnetic data from three new and three previously published sites from the NW part of the South Island (NW Nelson region), where sedimentary strata dated between 36 and 10 Ma overlie the crystalline Paleozoic basement assemblages of the Gondwana margin. Compared with reference directions from the Australian apparent polar wander path, none of the results provide evidence of post-Eocene vertical-axis rotation. This suggests that for the past 36 Myr NW Nelson has remained a strong, coherent block that has moved as a contiguous part of the Australian plate. This is in marked contrast to the strongly rotated nature of more outboard accreted terranes to the east. For example, the Hikurangi Margin in the North Island (NW of the Alpine Fault) and the Marlborough region in the NE of the South Island (SE of the Alpine Fault), have both undergone diverse clockwise rotations of up to 140° since the early Paleogene. The NW tip of the South Island seems to have acted as a rigid backstop relative to these more complex oroclinal deformations. We infer that, because of its relatively stiff bulk rheology, it has not been drawn into the distributed plate boundary rotational deformation associated with the New Zealand Orocline.

  14. Experiments of dike-induced deformation: Insights on the long-term evolution of divergent plate boundaries

    KAUST Repository

    Trippanera, D.

    2015-10-22

    The shallow transport of magma occurs through dikes causing surface deformation. Our understanding of the effects of diking at the surface is limited, especially on the long term, for repeated intrusive episodes. We use analogue models to study the upper crustal deformation induced by dikes. We insert metal plates within cohesive sand with three setups: in setup A, the intrusion rises upward with constant thickness and in setups B and C, the intrusion thickens at a fixed depth, with final rectangular (setup B) or triangular (setup C) shape in section. Setup A creates a doming delimited by reverse faults, with secondary apical graben, without close correspondence in nature. In setups B and C, a depression flanked by two uplifted areas is bordered by inward dipping normal faults propagating downward and, for deeper intrusions in setup B, also by inner faults, reverse at the surface; this deformation is similar to what is observed in nature, suggesting a consistent physical behavior. Dikes in nature initially propagate developing a mode I fracture at the tip, subsequently thickened by magma intrusion, without any host rock translation in the propagation direction (as in setup A). The deformation pattern in setups B and C depends on the intrusion depth and thickness, consistently to what is observed along divergent plate boundaries. The early deformation in setups B and C is similar to that from a single rifting episode (i.e., Lakagigar, Iceland, and Dabbahu, Afar), whereas the late stages resemble the structure of mature rifts (i.e., Krafla, Iceland), confirming diking as a major process in shaping divergent plate boundaries.

  15. The interpretation of crustal dynamics data in terms of plate motions and regional deformation near plate boundaries

    Science.gov (United States)

    Solomon, Sean C.

    During our participation in the NASA Crustal Dynamics Project under NASA contract NAS-27339 and grant NAG5-814 for the period 1982-1991, we published or submitted for publication 30 research papers and 52 abstracts of presentations at scientific meetings. In addition, five M.I.T. Ph.D. students (Eric Bergman, Steven Bratt, Dan Davis, Jeanne Sauber, Anne Sheehan) were supported wholly or in part by this project during their thesis research. Highlights of our research progress during this period include the following: application of geodetic data to determine rates of strain in the Mojave block and in central California and to clarify the relation of such strain to the San Andreas fault and Pacific-North American plate motions; application of geodetic data to infer post seismic deformation associated with large earthquakes in the Imperial Valley, Hebgen Lake, Argentina, and Chile; determination of the state of stress in oceanic lithosphere from a systematic study of the centroid depths and source mechanisms of oceanic intraplate earthquakes; development of models for the state of stress in young oceanic regions arising from the differential cooling of the lithosphere; determination of the depth extent and rupture characteristics of oceanic transform earthquakes; improved determination of earthquake slip vectors in the Gulf of California, an important data set for the estimation of Pacific-North American plate motions; development of models for the state of stress and mechanics of fold-and-thrust belts and accretionary wedges; development of procedures to invert geoid height, residual bathymetry, and differential body wave travel time residuals for lateral variations in the characteristic temperature and bulk composition of the oceanic upper mantle; and initial GPS measurements of crustal deformation associated with the Imperial-Cerro Prieto fault system in southern California and northern Mexico. Full descriptions of the research conducted on these topics may be

  16. Crustal deformation evidences for viscous coupling and fragmented lithosphere at the Nubia-Iberia plate boundary (Western Mediterranean)

    Science.gov (United States)

    Palano, Mimmo; González, Pablo J.; Fernández, José

    2016-04-01

    A spatially dense crustal velocity field, based on up to 15 years of GNSS observations at more than 380 sites and extensively covering the Iberian Peninsula and Northern Africa, allow us to provide new insights into two main tectonic processes currently occurring in this area. We detected a slow large-scale clockwise rotation of the Iberian Peninsula with respect to a local pole located closely to the northwestern sector of the Pyrenean mountain range (Palano et al., 2015). Although this crustal deformation pattern could suggest a rigid rotating lithosphere block, this model would predict significant shortening along the Western (off-shore Lisbon) and North Iberian margin which cannot totally ruled out but currently is not clearly observed. Conversely, we favour the interpretation that this pattern reflects the quasi-continuous straining of the ductile lithosphere in some sectors of South and Western Iberia in response to viscous coupling of the NW Nubia and Iberian plate boundary in the Gulf of Cádiz. Furthermore, the western Mediterranean basin appears fragmented into independent crustal tectonic blocks, which delimited by inherited lithospheric shear structures and trapped within the Nubia-Eurasia collision, are currently accommodating most of the plate convergence rate. Among these blocks, an (oceanic-like western) Algerian one is currently transferring a significant fraction of the Nubia-Eurasia convergence rate into the Eastern Betics (SE Iberia) and likely causing the eastward motion of the Baleares Promontory. Most of the observed crustal ground deformation can be attributed to processes driven by spatially variable lithospheric plate forces imposed along the Nubia-Eurasia convergence boundary. Nevertheless, the observed deformation field infers a very low convergence rates as observed also at the eastern side of the western Mediterranean, along the Calabro Peloritan Arc, by space geodesy (e.g. Palano, 2015). References Palano M. (2015). On the present

  17. A boundary-integral model for drop deformation between two parallel plates with non-unit viscosity ratio drops

    Science.gov (United States)

    Janssen, P. J. A.; Anderson, P. D.

    2008-10-01

    A boundary-integral method is presented for drop deformation between two parallel walls for non-unit viscosity ratio systems. To account for the effect of the walls the Green's functions are modified and all terms for the double-layer potential are derived. The full three-dimensional implementation is validated, and the model is shown to be accurate and consistent. The method is applied to study drop deformation in shear flow. An excellent match with small-deformation theory is found at low capillary numbers, and our results match with other BIM simulations for pressure-driven flows. For shear flow with moderate capillary numbers, we see that the behavior of a low-viscosity drop is similar to that of drop with a viscosity ratio of unity. High-viscosity drops, on the other hand, are prevented from rotating in shear flow, which results in a larger deformation, but less overshoot in the drop axes is observed. In contrast with unconfined flow, high-viscosity drops can be broken in shear flow between parallel plates; for low-viscosity drops the critical capillary number is higher in confined situations.

  18. Global crustal movement and tectonic plate boundary deformation constrained by the ITRF2008

    Directory of Open Access Journals (Sweden)

    Zhu Ze

    2012-08-01

    Full Text Available On the basis of the newly released International Terrestrial Reference Frame(ITRF2008 by the International Earth Rotation Service (IERS, a new global plate model ITRF2008 plate for the major plates is established. This ITRF2008-derived model is analyzed in comparison with NNR-NUVEL1A model, which is mainly based on geological and geophysical data. The Eurasia and Pacific plates display obvious differences in terms of the velocity fields derived from the two plate motion models. Plate acceleration is also introduced to characterize the differences of the two velocity fields which obtained from ITRF2008 -plate and NNR-NUVEL1A models for major individual plates. The results show that the Africa, South America and Eurasia plates are undergoing acceleration, while the North America and Australia plates are in the state of deceleration motion.

  19. Transients in Pacific/North American Plate Boundary Deformation: Synthesis and Modeling of GPS and Borehole Strain Observations

    Science.gov (United States)

    Solomon, Sean C.; Frey, H. V. (Technical Monitor)

    2002-01-01

    This is the Final Technical Report on research conducted between 1 June 1997 and 14 September 2001 entitled "Transients in Pacific/North American plate boundary deformation: Synthesis and modeling of GPS and borehole strain observations." As the project title implies, our effort involved a geodetic study of strain transients, i.e., temporal variations in deformation rates, that occur within plate boundary zones and their relationship to earthquakes and plate motions. Important transients occur during and following large earthquakes, and there are also strain transients not apparently associated with earthquakes. A particularly intriguing class of transients, for which there is a modest but growing list of examples, are preseismic anomalies. Such earthquake precursors, if further documented and understood, would have obvious importance for earthquake hazard mitigation. Because the timescales for these diverse transients range over at least 6 orders of magnitude (minutes to years), no single geodetic technique is optimum. We therefore undertook a systematic synthesis of Global Positioning Satellite (GPS) and borehole strainmeter data in three areas in California where there are adequate numbers of both types of instruments (or their equivalent): the San Francisco Bay region (within the Bay Area Regional Deformation network), southern California (within the Southern California Integrated GPS Network), and Parkfield (where a two-color laser system provides a proxy for continuous GPS measurements). An integral component of our study was the elucidation of the physical mechanisms by which such transients occur and propagate. We therefore initiated the development of multiple forward models, using two independent approaches. In the first, we explored the response to specified earthquake slip in viscoelastic models that incorporated failure criteria and the geometry of major faults in California. In the second approach, we examined the dynamical response of a complex

  20. An application of Global Positioning System data from the Plate Boundary Observatory for deformation monitoring purposes (Invited)

    Science.gov (United States)

    Murray-Moraleda, J. R.; Liu, Z.; Segall, P.

    2009-12-01

    The Plate Boundary Observatory (PBO) represents a major step forward in Global Positioning System (GPS) coverage for the western United States by increasing the spatial density of stations, generating daily position estimates, and providing the infrastructure for high-rate and real-time positioning. In addition to producing vital input for a wide range of crustal deformation studies, PBO significantly expands opportunities for monitoring and event response. This presentation will focus on one such effort. Data from large continuous GPS networks like PBO should be monitored for temporal changes, be they tectonic, volcanic, hydrologic, anthropogenic, or instrumental in origin. Since it is not feasible to review time series by eye on a daily basis, automated approaches are required. Here we apply a Kalman filtering based method, termed the Network Inversion Filter (Segall and Matthews, 1997; McGuire and Segall, 2003), to monitor daily GPS data for deformation-related transient signals. This approach relies on the spatial coherence of signals due to transient sources such as fault slip in order to separate them from spatially-localized time-dependent noise. The dense GPS coverage provided by PBO has augmented pre-existing continuous GPS networks making it now feasible to test this method in California. Results from synthetic tests using the >400 station southern California continuous GPS network configuration demonstrate this approach can extract fault slip signals from data contaminated by plausible noise processes. We will present results using real data from the San Francisco Bay Area and discuss the role and limitations of this methodology in hazard monitoring.

  1. Investigating crustal deformation associated with the North America-Pacific plate boundary in southern California with GPS geodesy

    Science.gov (United States)

    Spinler, Joshua C.

    The three largest earthquakes in the last 25 years in southern California occurred on faults located adjacent to the southern San Andreas fault, with the M7.3 1992 Landers and M7.1 1999 Hector Mine earthquakes occurring in the eastern California shear zone (ECSZ) in the Mojave Desert, and the M7.2 2010 El Mayor-Cucapah earthquake occurring along the Laguna Salada fault in northern Baja California, Mexico. The locations of these events near to but not along the southern San Andreas fault (SSAF) is unusual in that the last major event on the SSAF occurred more than 300 years ago, with an estimated recurrence interval of 215 +/- 25 years. The focus of this dissertation is to address the present-day deformation field along the North America-Pacific plate boundary in southern California and northern Baja California, through the analysis of GPS data, and elastic block and viscoelastic earthquake models to determine fault slip rates and rheological properties of the lithosphere in the plate boundary zone. We accomplish this in three separate studies. The first study looks at how strain is partitioned northwards along-strike from the southern San Andreas fault near the Salton Sea. We find that estimates for slip-rates on the southern San Andreas decrease from ~23 mm/yr in the south to ~8 mm/yr as the fault passes through San Gorgonio Pass to the northwest, while ~13-18 mm/yr of slip is partitioned onto NW-SE trending faults of the ECSZ where the Landers and Hector Mine earthquakes occurred. This speaks directly to San Andreas earthquake hazards, as a reduction in the slip rate would require greater time between events to build up enough slip deficit in order to generate a large magnitude earthquake. The second study focuses on inferring the rheological structure beneath the Salton Trough region. This is accomplished through analysis of postseismic deformation observed using a set of the GPS data collected before and after the 2010 El Mayor-Cucapah earthquake. By

  2. Beyond plate tectonics - Looking at plate deformation with space geodesy

    Science.gov (United States)

    Jordan, Thomas H.; Minster, J. Bernard

    1988-01-01

    The requirements that must be met by space-geodetic systems in order to constrain the horizontal secular motions associated with the geological deformation of the earth's surface are explored. It is suggested that in order to improve existing plate-motion models, the tangential components of relative velocities on interplate baselines must be resolved to an accuracy of less than 3 mm/yr. Results indicate that measuring the velocities between crustal blocks to + or - 5 mm/yr on 100-km to 1000-km scales can produce geologically significant constraints on the integrated deformation rates across continental plate-boundary zones such as the western United States.

  3. Beyond plate tectonics - Looking at plate deformation with space geodesy

    Science.gov (United States)

    Jordan, Thomas H.; Minster, J. Bernard

    1988-01-01

    The requirements that must be met by space-geodetic systems in order to constrain the horizontal secular motions associated with the geological deformation of the earth's surface are explored. It is suggested that in order to improve existing plate-motion models, the tangential components of relative velocities on interplate baselines must be resolved to an accuracy of less than 3 mm/yr. Results indicate that measuring the velocities between crustal blocks to + or - 5 mm/yr on 100-km to 1000-km scales can produce geologically significant constraints on the integrated deformation rates across continental plate-boundary zones such as the western United States.

  4. Plate boundary deformation in North Iceland during 1992–2009 revealed by InSAR time-series analysis and GPS

    KAUST Repository

    Metzger, Sabrina

    2014-08-20

    In North Iceland, extensional plate motion is accommodated by the Northern Volcanic Zone, a set of en-echelon volcanic systems, and the Tjörnes Fracture Zone, a transform offset in the mid-Atlantic Ridge consisting of two parallel transform lineaments. The southern lineament, the Húsavík–Flatey fault, is a 100 km-long right-lateral strike slip fault that has not ruptured for more than 140 years and poses a significant seismic hazard to Húsavík, a fishing town located by the fault, and to other coastal communities. We present results of InSAR time-series analysis data spanning almost two decades (1992–2009) that show extensional and interseismic deformation within the Northern Volcanic Zone and the on-shore part of the Tjörnes Fracture Zone. The results also exhibit transient inflation at Theistareykir volcano, deflation at Krafla central volcano and a broad uplift north of Krafla. The current plate extension is not uniform across the Northern Volcanic Zone, but concentrated at the western fissures of the Theistareykir volcanic system and the outermost fissures of the Krafla fissure swarm. We combine a back-slip plate boundary model with a set of point pressure sources representing volcanic changes to describe the current extensional plate boundary deformation and update the previous estimations of the locking depth and slip rate of the Húsavík–Flatey fault that were based on GPS data alone. Using different combinations of input data, we find that the Húsavík–Flatey fault has a locking depth of 6–10 km and, with a slip rate of 6–9 mm/yr, is accommodating about a third of the full transform motion. We furthermore show that while the InSAR data provide important constraints on the volcanic deformation within the NVZ, they do not significantly improve the model parameter estimation for the HFF, as the dense GPS network appears to better capture the deformation across the fault.

  5. The INGV National Earthquake Centre research infrastructure to study the plate boundary deformation in the Central Mediterranean

    Science.gov (United States)

    Selvaggi, Giulio; Mazza, Salvatore; Delladio, Alberto; Cecere, Gianpaolo; Devoti, Roberto

    2010-05-01

    To understand the complex kinematics within the plate boundary zone between Africa and Eurasia in the central Mediterranean, INGV installed a monitoring system based on broad-band seismometers, CGPS and strong motion sensors, most of them co-located in the same site. Established since early '80 with some tens of short period seismometers and analogue transmission, now the monitoring system consists of more than 200 real time broad-band seismometers, 140 CGPS and about 80 strong motions connected to different centres of acquisition. A dedicated disaster recovery guarantees continuity of acquisition and data sharing among centres. Beside essential services connected to Italian Civil Protection agency and basic research, we believe that our network represents an important reality in the framework of the EPOS infrastructure and we strongly support the idea of an European research approach to data sharing among the scientific community. In the presentation we will show the network, from the sites to the acquisition centres, and the level of the seismic and geodetic products and the primary scientific targets addressed when designing the networks.

  6. 3-D simulation of temporal change in tectonic deformation pattern and evolution of the plate boundary around the Kanto Region of Japan due to the collision of the Izu-Bonin Arc

    Science.gov (United States)

    Hashima, A.; Sato, T.; Ito, T.; Miyauchi, T.; Furuya, H.; Tsumura, N.; Kameo, K.; Yamamoto, S.

    2010-12-01

    The Kanto region of Japan is in a highly complex tectonic setting with four plates interacting with each other: beneath Kanto, situated on the Eurasian and North American plates, the Philippine sea plate subducts and the Pacific plate further descends beneath the North American and Philippine sea plates, forming the unique trench-trench-trench triple junction on the earth. In addition, the Izu-Bonin (Ogasawara) arc on the Philippine sea plate is colliding with the Japan islands, which is considered to be a significant effect on the tectonics of Kanto. To reveal the present crustal structure and the present internal stress fields in such a complex tectonic setting, it is essential to comprehend them through the long-term tectonic evolution process. In this study, we estimate the temporal change in tectonic deformation pattern along with the geometry of the plate boundary around Kanto by numerical simulation with a kinematic plate subduction model based on the elastic dislocation theory. This model is based on the idea that mechanical interaction between plates can rationally be represented by the increase of the displacement discontinuity (dislocation) across plate interfaces. Given the 3-D geometry of plate interfaces, the distribution of slip rate vectors for simple plate subduction can be obtained directly from relative plate velocities. In collision zones, the plate with arc crust cannot easily descend because of its buoyancy. This can be represented by giving slip-rate deficit. When crustal deformation occurs, it also causes change in geometry of the plate boundary itself. This geometry change sensitively affects mechanical interaction at the plate boundary. Then the renewed plate-to-plete interaction alters crustal deformation rates. This feedback system has a large effect on collision zones. Indeed, the plate boundary around the Izu peninsula, the northernmost end of the Izu-Bonin arc, intends landward as large as 100 km. Iterating this effect sequentially

  7. Diffuse oceanic plate boundaries: Strain rates, vertically averaged rheology, and comparisons with narrow plate boundaries and stable plate interiors

    Science.gov (United States)

    Gordon, Richard G.

    Diffuse plate boundaries occur in both oceanic and continental lithosphere and cover ≈ 15% of Earth's solid surface. The fastest plate speeds accommodated across diffuse oceanic plate boundaries are ≈ 15 mm/yr. The smallest strain rates averaged across narrow plate boundaries are at least 102 times larger than the largest strain rates across diffuse oceanic plate boundaries and at least 102 times larger than those across stable plate interiors. The effective viscosity (ηeff) of the lithosphere is estimated from the ratio of vertically averaged shear stresses to strain rates for three tectonic settings: (i) oceanic transform fault zones, for which ηeff = 3 ×1016 to 5×1019 Pa s, comparable to estimates for the asthenosphere, (ii) diffuse oceanic plate boundaries, for which ηeff = 1×1023 to 6×l023 Pa s, ≈ 10 times larger than for diffuse continental plate boundaries, and (iii) stable plate interiors, for which ηeff = 1x1024 to 2×1027 Pa s. The rheology of oceanic lithosphere over times longer than earthquake cycles is modeled as a plastic layer overlying a layer that deforms by creeping flow [Martinod and Davy, 1992]. Oceanic lithosphere deforms when the yield strength of the upper lithosphere is exceeded. The vertically averaged rheology of deforming oceanic lithosphere can be approximated by a power-law fluid for which ɛ. ∝ (τs)n where ɛ. is the rate of shear strain and τs is the shear stress. If the ratio of the yield strength of the upper lithosphere to the force required to deform the lower lithosphere at a strain rate of 10-16 s-1 is varied from 10-2 to 102 , the calculated value of n varies from ≈3 to ≈300. The map-view aspect ratio of a deforming zone in a thin sheet of power-law fluid is proportional to n-½ [England et al., 1985]. A profile of displacement versus distance inferred from a seismic profile across the Central Indian Basin (India-Capricorn diffuse oceanic plate boundary), where the lithosphere is about 60-Myr old

  8. RELATIVE MOTION AND DEFORMATION OF PACIFIC PLATE FROM SPACE GEODESY

    Institute of Scientific and Technical Information of China (English)

    JinShuanggen; ZhuWenyao

    2003-01-01

    The circum-Pacific tectonic system that contains of convergent, divergent and transform boundaries, is the most active region of volcanoes and earthquakes in the world, and involves many important theoretical questions in geosciences. The relative motion and deformation of Pacific plate is still an active subject of research. In this note, we analyze the deformation of Pacific plate and obtain reliable results of the relative motion rates at the circum-Pacific boundaries based on space geodetic data, which reveals the present-day motion characteristics of Pacific plate.

  9. Detection and modeling of low amplitude deformation signals in the EarthScope Plate Boundary Observatory (PBO)

    Science.gov (United States)

    Meertens, C. M.; Wahr, J. M.; van Dam, T. M.; Herring, T.

    2011-12-01

    The high quality and density of the 1,200 station PBO GPS network allow for the identification of very small ~1 mm level deformation signals. In the mountainous areas of California, Oregon and Washington, seasonal signals and longer term trends in the vertical component of motion are shown to be dominated by the effects of natural hydrological loading. Contributions from localized anthropogenic loading effects due to changes in water storage in reservoirs are also seen. Recent analysis also reveals significant hydrological effects in the horizontal component. Modeling of both vertical and horizontal hydrologic deformation using the Global Land Data Assimilation System (GLDAS) and a variety of land surface models (NOAH, MOSAIC, VIC and CLM) shows promise that these hydrologic effects can be removed from the overall signal to be studied separately and to reveal slowly accumulating tectonic deformation in the remaining signal. GPS data products used for this analysis are the precise coordinate time series produced on a daily basis by PBO Analysis Centers at New Mexico Institute of Mining and Technology and at Central Washington University and combined by the Analysis Center Coordinator at the Massachusetts Institute of Technology. Observed seasonal vertical signals as small as 1 mm and up to 10 mm amplitude and horizontal signals of 2 mm or less amplitude are evident in stations in mountainous areas. The peak seasonal uplift is in October and is correlated to modeled hydrological loading effects. Mountainous areas appear to be responding elastically to variations in the load of the water contained in surface soil, fractures, and snow. In contrast, seasonal signals observed at stations in basins are primarily sensitive to anthropogenic water level changes coupled with poroelastic effects and are out of phase with loading signals in mountains. Over longer periods, trends in California between 2004 and 2009 show uplift at ~1.5 mm/yr as the net water load in the mountains

  10. The seismotectonics of plate boundaries

    Science.gov (United States)

    Berger, J.; Brune, J. N.; Goodkind, J.; Wyatt, F.; Agnew, D. C.; Beaumont, C.

    1981-01-01

    Research on the seismotectonics of plate boundaries is summarized. Instrumental development and an observational program designed to study various aspects of the seismotectonics of southern California and the northern Gulf of California are described. A unique superconducting gravimeter was further developed and supported under this program for deployment and operation at several sites. Work on Earth tides is also discussed.

  11. Active tectonic deformation of the western Indian plate boundary: A case study from the Chaman Fault System

    Science.gov (United States)

    Crupa, Wanda E.; Khan, Shuhab D.; Huang, Jingqiu; Khan, Abdul S.; Kasi, Aimal

    2017-10-01

    Collision of the Eurasian and Indian plates has resulted in two spatially offset subduction zones, the Makran subduction zone to the south and the Himalayan convergent margin to the north. These zones are linked by a system of left-lateral strike-slip faults known as the Chaman Fault System, ∼1200 km, which spans along western Pakistan. Although this is one of the greatest strike-slip faults, yet temporal and spatial variation in displacement has not been adequately defined along this fault system. This study conducted geomorphic and geodetic investigations along the Chaman Fault in a search for evidence of spatial variations in motion. Four study areas were selected over the span of the Chaman Fault: (1) Tarnak-Rud area over the Tarnak-Rud valley, (2) Spinatizha area over the Spinatizha Mountain Range, (3) Nushki area over the Nushki basin, and (4) Kharan area over the northern tip of the Central Makran Mountains. Remote sensing data allowed for in depth mapping of different components and faults within the Kohjak group. Wind and water gap pairs along with offset rivers were identified using high-resolution imagery and digital-elevation models to show displacement for the four study areas. The mountain-front-sinuosity ratio, valley height-to-width-ratio, and the stream-length-gradient index were calculated and used to determine the relative tectonic activity of each area. These geomorphic indices suggest that the Kharan area is the most active and the Tarnak-Rud area is the least active. GPS data were processed into a stable Indian plate reference frame and analyzed. Fault parallel velocity versus fault normal distance yielded a ∼8-10 mm/yr displacement rate along the Chaman Fault just north of the Spinatizha area. InSAR data were also integrated to assess displacement rates along the fault system. Geodetic data support that ultra-slow earthquakes similar to those that strike along other major strike-slip faults, such as the San Andreas Fault System, are

  12. Investigating the deformation of upper crustal faults at the N-Chilean convergent plate boundary at different scales using high-resolution topography datasets and creepmeter measurements

    Science.gov (United States)

    Ewiak, O.; Victor, P.; Ziegenhagen, T.; Oncken, O.

    2012-04-01

    The Chilean convergent plate boundary is one of the tectonically most active regions on earth and prone to large megathrust earthquakes as e. g. the 2010 Mw 8.8 Maule earthquake which ruptured a mature seismic gap in south-central Chile. In northern Chile historical data suggests the existence of a seismic gap between Arica and Mejillones Peninsula (MP), which has not ruptured since 1877. Further south, the 1995 Mw 8.0 Antofagasta earthquake ruptured the subduction interface between MP and Taltal. In this study we investigate the deformation at four active upper plate faults (dip-slip and strike-slip) located above the coupling zone of the subduction interface. The target faults (Mejillones Fault - MF, Salar del Carmen Fault - SCF, Cerro Fortuna Fault - CFF, Chomache Fault - CF) are situated in forearc segments, which are in different stages of the megathrust seismic cycle. The main question of this study is how strain is accumulated in the overriding plate, what is the response of the target faults to the megathrust seismic cycle and what are the mechanisms / processes involved. The hyper arid conditions of the Atacama desert and the extremely low erosion rates enable us to investigate geomorphic markers, e .g. fault scarps and knickpoints, which serve as a record for upper crustal deformation and fault activity about ten thousands years into the past. Fault scarp data has been acquired with Differential-GPS by measuring high-resolution topographic profiles perpendicular to the fault scarps and along incised gullies. The topographic data show clear variations between the target faults which possibly result from their position within the forearc. The surveyed faults, e. g. the SCF, exhibit clear along strike variations in the morphology of surface ruptures attributed to seismic events and can be subdivided into individual segments. The data allows us to distinguish single, composite and multiple fault scarps and thus to detect differences in fault growth initiated

  13. Far-Field Deformation Resulting from Rheologic Differences Interacting with Tectonic Stresses: An Example from the Pacific/Australian Plate Boundary in Southern New Zealand

    Directory of Open Access Journals (Sweden)

    Phaedra Upton

    2014-07-01

    Full Text Available The Miocene in Southern New Zealand was dominated by strike-slip tectonics. Stratigraphic evidence from this time attests to two zones of subsidence in the south: (a a middle Cenozoic pull-apart basin and (b a regionally extensive subsiding lake complex, which developed east and distal to the developing plate boundary structure. The lake overlay a block of crust with a significantly weak mid-crustal section and we pose the question: can rheological transitions at an angle to a plate boundary produce distal subsidence and/or uplift? We use stratigraphic, structural and geophysical observations from Southern New Zealand to constrain three-dimensional numerical models for a variety of boundary conditions and rheological scenarios. We show that coincident subsidence and uplift can result from purely strike-slip boundary conditions interacting with a transition from strong to weak to strong mid-crustal rheology. The resulting pattern of vertical displacement is a function of the symmetry or asymmetry of the boundary conditions and the extent and orientation of the rheological transitions. For the Southern New Zealand case study, subsidence rates of ~0.1 mm/yr are predicted for a relative plate motion of 25 mm/yr, leading to ~500 m of subsidence over a 5 Ma time period, comparable to the thickness of preserved lacustrine sediments.

  14. The Okhotsk Plate and the Eurasia-North America plate boundary zone.

    Science.gov (United States)

    Hindle, David; Mackey, Kevin

    2014-05-01

    The Eurasia-North America plate boundary zone transitions from spreading at rates of ~ 25mm/yr in the North Atlantic, to compression at rates of ~ 5mm/yr in the region of the Okhotsk plate. Because the pole of rotation between Eurasia and North America lies more or less on their mutual boundary, there is a linear change in rate along the boundary, and regions near the euler pole are subject to extremely low deformation rates. The Okhotsk - Eurasia - North America triple junction lies slightly south of the rotation pole, placing the Okhotsk plate entirely in a weakly contractional setting. Regions near the triple junction absorb 1mm/yr contraction. Further south, towards the shoreline of the Okhotsk sea, up to 5 mm/yr contraction may be absorbed within the plate. How shortening is accommodated across the boundary remains an open question. One possibility is wholesale extrusion of the entire Okhotsk plate (or possibly its northwestern corner) along two plate boundary strike slip faults (Eurasia-Okhostk and North America Okhotsk). The problem with this model is that the seismic record does not presently clearly support it, with the largest events distributed both within the plate interior and on its boundaries. This may suggest that instead, the Okhotsk plate, and particularly its north-western end, consists of a series of smaller blocks which shuffle against each other, partially accommodating extrusion, but also permitting some internal deformation and change of shape of the Okhotsk plate itself. We present analyses of the very sparse seismic record from the region, as well as geometric-kinematic, tectonic models of the possible deformation of northwest Okhotsk to try to better understand the different probabilities of how this slowly deforming plate boundary zone is behaving.

  15. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    Faical Ramdani; Omar Kettani; Benaissa Tadili

    2015-06-01

    Seismic triggering at plate boundaries has a very complex nature that includes seismic events at varying distances. The spatial orientation of triggering cannot be reduced to sequences from the main shocks. Seismic waves propagate at all times in all directions, particularly in highly active zones. No direct evidence can be obtained regarding which earthquakes trigger the shocks. The first approach is to determine the potential linked zones where triggering may occur. The second step is to determine the causality between the events and their triggered shocks. The spatial orientation of the links between events is established from pre-ordered networks and the adapted dependence of the spatio-temporal occurrence of earthquakes. Based on a coefficient of synchronous seismic activity to grid couples, we derive a network link by each threshold. The links of high thresholds are tested using the coherence of time series to determine the causality and related orientation. The resulting link orientations at the plate boundary conditions indicate that causal triggering seems to be localized along a major fault, as a stress transfer between two major faults, and parallel to the geothermal area extension.

  16. UNSYMMETRICAL LARGE DEFORMATION PROBLEM OF ORTHOTROPIC PLATES

    Institute of Scientific and Technical Information of China (English)

    王新志; 赵永刚; 叶开沅; 黄达文

    2002-01-01

    Based upon the theory of anisotropic plates, the unsymmetrical large deformation equations of orthotropic circular plates were derived. By using Fourier series, the partial differential equations of this problem can be transformed into sets of nonlinear differential equations. And the procedure to solve the problem using the iterative method is given.

  17. A diffuse plate boundary model for Indian Ocean tectonics

    Science.gov (United States)

    Wiens, D. A.; Demets, C.; Gordon, R. G.; Stein, S.; Argus, D.

    1985-01-01

    It is suggested that motion along the virtually aseismic Owen fracture zone is negligible, so that Arabia and India are contained within a single Indo-Arabian plate divided from the Australian plate by a diffuse boundary. The boundary is a zone of concentrated seismicity and deformation commonly characterized as 'intraplate'. The rotation vector of Australia relative to Indo-Arabia is consistent with the seismologically observed 2 cm/yr of left-lateral strike-slip along the Ninetyeast Ridge, north-south compression in the Central Indian Ocean, and the north-south extension near Chagos.

  18. Mixed boundary conditions for piezoelectric plates

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    For plate bending and stretching problems in piezoelectric materials,the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate mixed boundary conditions accurate to all order.A decay analysis technique is used to establish necessary conditions that the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the plate.For the case of axisymmetric bending and stretching of a circular plate,these decaying state conditions are obtained explicitly for the first time when the mixed conditions are imposed on the plate edge.They are then used for the correct formulation of boundary conditions for the interior solution.

  19. Deformation of vortex patches by boundaries

    CERN Document Server

    Crosby, A; Morrison, P J

    2013-01-01

    The deformation of two-dimensional vortex patches in the vicinity of fluid boundaries is investigated. The presence of a boundary causes an initially circular patch of uniform vorticity to deform. Sufficiently far away from the boundary, the deformed shape is well approximated by an ellipse. This leading order elliptical deformation is investigated via the elliptic moment model of Melander, Zabusky & Styczek [M. V. Melander, N. J. Zabusky & A. S. Styczek, J. Fluid. Mech., 167, 95 (1986)]. When the boundary is straight, the centre of the elliptic patch remains at a constant distance from the boundary, and the motion is integrable. Furthermore, since the straining flow acting on the patch is constant in time, the problem is that of an elliptic vortex patch in constant strain, which was analysed by Kida [S. Kida, J. Phys. Soc. Japan, 50, 3517 (1981)]. For more complicated boundary shapes, such as a square corner, the motion is no longer integrable. Instead, there is an adiabatic invariant for the motion....

  20. Plate tectonics and crustal deformation around the Japanese Islands

    Science.gov (United States)

    Hashimoto, Manabu; Jackson, David D.

    1993-01-01

    We analyze over a century of geodetic data to study crustal deformation and plate motion around the Japanese Islands, using the block-fault model for crustal deformation developed by Matsu'ura et al. (1986). We model the area including the Japanese Islands with 19 crustal blocks and 104 faults based on the distribution of active faults and seismicity. Geodetic data are used to obtain block motions and average slip rates of faults. This geodetic model predicts that the Pacific plate moves N deg 69 +/- 2 deg W at about 80 +/- 3 mm/yr relative to the Eurasian plate which is much lower than that predicted in geologic models. Substantial aseismic slip occurs on the subduction boundaries. The block containing the Izu Peninsula may be separated from the rigid part of the Philippine Sea plate. The faults on the coast of Japan Sea and the western part of the Median Tectonic Line have slip rates exceeding 4 mm/yr, while the Fossa Magna does not play an important role in the tectonics of the central Japan. The geodetic model requires the division of northeastern Japan, contrary to the hypothesis that northeastern Japan is a part of the North American plate. Owing to rapid convergence, the seismic risk in the Nankai trough may be larger than that of the Tokai gap.

  1. Plate tectonics and crustal deformation around the Japanese Islands

    Science.gov (United States)

    Hashimoto, Manabu; Jackson, David D.

    1993-01-01

    We analyze over a century of geodetic data to study crustal deformation and plate motion around the Japanese Islands, using the block-fault model for crustal deformation developed by Matsu'ura et al. (1986). We model the area including the Japanese Islands with 19 crustal blocks and 104 faults based on the distribution of active faults and seismicity. Geodetic data are used to obtain block motions and average slip rates of faults. This geodetic model predicts that the Pacific plate moves N deg 69 +/- 2 deg W at about 80 +/- 3 mm/yr relative to the Eurasian plate which is much lower than that predicted in geologic models. Substantial aseismic slip occurs on the subduction boundaries. The block containing the Izu Peninsula may be separated from the rigid part of the Philippine Sea plate. The faults on the coast of Japan Sea and the western part of the Median Tectonic Line have slip rates exceeding 4 mm/yr, while the Fossa Magna does not play an important role in the tectonics of the central Japan. The geodetic model requires the division of northeastern Japan, contrary to the hypothesis that northeastern Japan is a part of the North American plate. Owing to rapid convergence, the seismic risk in the Nankai trough may be larger than that of the Tokai gap.

  2. Highly variable coastal deformation in the 2016 MW7.8 Kaikōura earthquake reflects rupture complexity along a transpressional plate boundary

    Science.gov (United States)

    Clark, K. J.; Nissen, E. K.; Howarth, J. D.; Hamling, I. J.; Mountjoy, J. J.; Ries, W. F.; Jones, K.; Goldstien, S.; Cochran, U. A.; Villamor, P.; Hreinsdóttir, S.; Litchfield, N. J.; Mueller, C.; Berryman, K. R.; Strong, D. T.

    2017-09-01

    Coseismic coastal deformation is often used to understand slip on offshore faults in large earthquakes but in the 2016 MW 7.8 Kaikōura earthquake multiple faults ruptured across and sub-parallel to the coastline. Along ∼110 km of coastline, a rich dataset of coastal deformation comprising airborne lidar differencing, field surveying and satellite geodesy reveals highly variable vertical displacements, ranging from -2.5 to 6.5 m. These inform a refined slip model for the Kaikōura earthquake which incorporates changes to the slip on offshore faults and inclusion of an offshore reverse crustal fault that accounts for broad, low-amplitude uplift centered on Kaikōura Peninsula. The exceptional detail afforded by differential lidar and the high variability in coastal deformation combine to form the highest-resolution and most complex record of coseismic coastal deformation yet documented. This should prompt reassessment of coastal paleoseismic records that may not have considered multi-fault ruptures and high complexity deformation fields.

  3. Deformation of the Northwestern Okhotsk Plate: How is it happening?

    OpenAIRE

    Hindle, D; Fujita, K.; Mackey, K

    2009-01-01

    The Eurasia (EU) – North America (NA) plate boundary zone across Northeast Asia still presents many open questions within the plate tectonic paradigm. Constraining the geometry and number of plates or microplates present in the plate boundary zone is especially difficult because of the location of the EU-NA euler pole close to or even upon the EU-NA boundary. One of the major challenges remains the geometry of the Okhotsk plate (OK). whose northwestern portion terminates on ...

  4. Turbulent boundary layer over flexible plates

    Science.gov (United States)

    Rostami, Parand; Ioppolo, Tindaro

    2016-11-01

    This research describes the structure of a turbulent boundary layer flow with a zero pressure gradient over elastic plates. The elastic plates made of a thin aluminum sheets with thickness between 50 and 500 microns were placed on the floor of a subsonic wind tunnel and exposed to a turbulent boundary layer flow with a free stream velocity between 20m/s and 100m/s. The ceiling of the test section of the wind tunnel is adjustable so that a nearly zero pressure gradient is obtained in the test section. Hot-wire anemometry was used to measure the velocity components. Mean, fluctuating velocities and Reynolds stresses will be presented and compared with the values of a rigid plate.

  5. BOLIVAR & GEODINOS: Investigations of the Southern Caribbean Plate Boundary

    Science.gov (United States)

    Levander, A.; Schmitz, M.; Working Groups, B.

    2006-12-01

    , and is associated with broad uplift of the coastal regions. This is likely a site of continental growth. 2) The accretionary wedge terranes of the Southern Caribbean Deformed Belt formed in the Neogene, and extend as far east as the Aves Ridge. They result from SA overriding the CAR LIP, which for a number of reasons, we do not regard as normal subduction. 3) Igneous rocks on the islands of the Leeward Antilles arc, Aruba to Los Testigos, show a steady decrease in age from west to east (94.7-37.4 Ma), suggesting that the islands have been progressively captured from the Antilles arc by the plate boundary during the prolonged island arc-continent collision. Terrane capture models thus far cannot completely explain the data. 4) High (> 6.5 km/s) P-velocity bodies are found in the shallow crust along the main strike-slip faults along much of the plate boundary. We interpret these as elements of the HP/LT metamorphic terranes found in the adjacent thrust belts of central Venezuela. This suggests to us that displacement partitioning in the trench and subsequent strike-slip both play important roles in exhumation of the HP/LT terranes. 5) Crustal thickness variations in the plate boundary region are large (> 10 km), of short spatial wavelength (< 100 km), and indicate that the highest elevations of the coastal mountain belts are not supported isostatically.

  6. Contemporary Crustal Motion and Deformation of South America Plate

    Institute of Scientific and Technical Information of China (English)

    JIN Shuanggen; ZHU Wenyao

    2003-01-01

    This paper presents the contemporary motion and active deformation of South America plate and relative motion of Nazca-South America plate using space geodetic data. The South America plate is moving at average 14.5 mm/a with an azimuth of 15.2° and shrinking in the west-east at 10. 9 mm/a. The geodetic deformations of sites with respect to the South America plate are in quite good agreement with the estimated deformations from NNR-NUVEL1A, but the deformation of the western South America regions is very large.

  7. How transpressive is the northern Caribbean plate boundary?

    Science.gov (United States)

    Corbeau, J.; Rolandone, F.; Leroy, S.; Meyer, B.; Mercier de Lépinay, B.; Ellouz-Zimmermann, N.; Momplaisir, R.

    2016-04-01

    Transpressive deformation at the northern Caribbean plate boundary is accommodated mostly by two major strike-slip faults, but the amount and location of accommodation of the compressional component of deformation are still debated. We collected marine geophysical data including multibeam bathymetry and multichannel seismic reflection profiles along this plate boundary around Hispaniola, in the Jamaica Passage, and in the Gulf of Gonâve. The data set allows us to image the offshore active strike-slip faults as well as the compressional structures. We confirm that the Enriquillo-Plantain-Garden Fault Zone (EPGFZ) in the Jamaica Passage has a primary strike-slip motion, as indicated by active left-lateral strike-slip-related structures, i.e., restraining bend, asymmetrical basin, en echelon pressures ridges, and horsetail splay. Based on topographic cross sections across the EPGFZ, we image a very limited compressional component, if any, for at least the western part of the Jamaica Passage. Toward the east of the Jamaica Passage, the fault trace becomes more complex, and we identify adjacent compressional structures. In the Gulf of Gonâve, distributed folding and thrust faulting of the most recent sediments indicate active pervasive compressional tectonics. Estimates of shortening in the Jamaica Passage and in the Gulf of Gonâve indicate an increase of the compressional component of deformation toward the east, which nonetheless remains very small compared to that inferred from block modeling based on GPS measurements.

  8. Influence of Subducting Plate Geometry on Upper Plate Deformation at Orogen Syntaxes: A Thermomechanical Modeling Approach

    Science.gov (United States)

    Nettesheim, Matthias; Ehlers, Todd; Whipp, David

    2016-04-01

    Syntaxes are short, convex bends in the otherwise slightly concave plate boundaries of subduction zones. These regions are of scientific interest because some syntaxes (e.g., the Himalaya or St. Elias region in Alaska) exhibit exceptionally rapid, focused rock uplift. These areas have led to a hypothesized connection between erosional and tectonic processes (top-down control), but have so far neglected the unique 3D geometry of the subducting plates at these locations. In this study, we contribute to this discussion by exploring the idea that subduction geometry may be sufficient to trigger focused tectonic uplift in the overriding plate (a bottom-up control). For this, we use a fully coupled 3D thermomechanical model that includes thermochronometric age prediction. The downgoing plate is approximated as spherical indenter of high rigidity, whereas both viscous and visco-plastic material properties are used to model deformation in the overriding plate. We also consider the influence of the curvature of the subduction zone and the ratio of subduction velocity to subduction zone advance. We evaluate these models with respect to their effect on the upper plate exhumation rates and localization. Results indicate that increasing curvature of the indenter and a stronger upper crust lead to more focused tectonic uplift, whereas slab advance causes the uplift focus to migrate and thus may hinder the emergence of a positive feedback.

  9. Hidden Earthquake Potential in Plate Boundary Transition Zones

    Science.gov (United States)

    Furlong, Kevin P.; Herman, Matthew; Govers, Rob

    2017-04-01

    Plate boundaries can exhibit spatially abrupt changes in their long-term tectonic deformation (and associated kinematics) at triple junctions and other sites of changes in plate boundary structure. How earthquake behavior responds to these abrupt tectonic changes is unclear. The situation may be additionally obscured by the effects of superimposed deformational signals - juxtaposed short-term (earthquake cycle) kinematics may combine to produce a net deformational signal that does not reflect intuition about the actual strain accumulation in the region. Two examples of this effect are in the vicinity of the Mendocino triple junction (MTJ) along the west coast of North America, and at the southern end of the Hikurangi subduction zone, New Zealand. In the region immediately north of the MTJ, GPS-based observed crustal displacements (relative to North America (NAm)) are intermediate between Pacific and Juan de Fuca (JdF) motions. With distance north, these displacements rotate to become more aligned with JdF - NAm displacements, i.e. to motions expected along a coupled subduction interface. The deviation of GPS motions from the coupled subduction interface signal near the MTJ has been previously interpreted to reflect clock-wise rotation of a coastal, crustal block and/or reduced coupling at the southern Cascadia margin. The geologic record of crustal deformation near the MTJ reflects the combined effects of northward crustal shortening (on geologic time scales) associated with the MTJ Crustal Conveyor (Furlong and Govers, 1999) overprinted onto the subduction earthquake cycle signal. With this interpretation, the Cascadia subduction margin appears to be well-coupled along its entire length, consistent with paleo-seismic records of large earthquake ruptures extending to its southern limit. At the Hikurangi to Alpine Fault transition in New Zealand, plate interactions switch from subduction to oblique translation as a consequence of changes in lithospheric structure of

  10. Dike-induced contraction along oceanic and continental divergent plate boundaries

    KAUST Repository

    Trippanera, D.

    2014-10-28

    The axis of divergent plate boundaries shows extension fractures and normal faults at the surface. Here we present evidence of contraction along the axis of the oceanic ridge of Iceland and the continental Main Ethiopian Rift. Contraction is found at the base of the tilted hanging wall of dilational normal faults, balancing part of their extension. Our experiments suggest that these structures result from dike emplacement. Multiple dike injection induces subsidence above and uplift to the sides of the dikes; the transition in between is accommodated by reverse faults and subsequent peripheral inward dipping normal faults. Our results suggest that contraction is a direct product of magma emplacement along divergent plate boundaries, at various scales, marking a precise evolutionary stage and initiating part of the extensional structures (extension fractures and normal faults). Key Points Contraction along divergent plate boundaries results from dike emplacementContraction generates extensional structures along divergent plate boundariesSurface deformation along divergent plate boundaries may be magma induced

  11. DIFFERENTIAL QUADRATURE METHOD FOR BENDING OF ORTHOTROPIC PLATES WITH FINITE DEFORMATION AND TRANSVERSE SHEAR EFFECTS

    Institute of Scientific and Technical Information of China (English)

    李晶晶; 程昌钧

    2004-01-01

    Based on the Reddy' s theory of plates with the effect of higher-order shear deformations, the governing equations for bending of orthotropic plates with finite deformations were established. The differential quadrature ( DQ ) method of nonlinear analysis to the problem was presented. New DQ approach, presented by Wang and Bert (DQWB), is extended to handle the multiple boundary conditions of plates. The techniques were also further extended to simplify nonlinear computations. The numerical convergence and comparison of solutions were studied. The results show that the DQ method presented is very reliable and valid. Moreover, the influences of geometric and material parameters as well as the transverse shear deformations on nonlinear bending were investigated.Numerical results show the influence of the shear deformation on the static bending of orthotropic moderately thick plate is significant.

  12. The GEORED and Plate Boundary Observatory Engineer Exchange Program

    Science.gov (United States)

    Feaux, K.; Mora-Paez, H.

    2007-05-01

    In early 2007, the Colombian Institute of Geology and Mining - INGEOMINAS initiated GEORED (Geodesia: Red de Estudios de Deformación) in order to increase the knowledge of the geodynamics of northwestern South America. GEORED is an essential tool for determining crustal deformation and is primary in the analysis of inter- plate and intraplate deformation and the present seismic cycle. Some of the objectives of the project are to improve the technical, scientific, and operational capabilities of Colombian scientists regarding tectonic and volcanic deformation in Colombia, to implement a Colombian GPS permanent network for the study of geodynamics, with near real-time data retrieval and processing, and to establish a high precision geodetic reference frame for multipurpose activities within INGEOMINAS. Phase 1 of GEORED, which includes the installation of 30 permanent GPS stations in Colombia, will commence in early 2007. The Plate Boundary Observatory (PBO), part of the larger NSF-funded EarthScope project managed by UNAVCO, will study the three-dimensional strain field resulting from active plate boundary deformation across the Western United States. PBO is a large construction project involving the reconnaissance, permitting, installation, documentation, and maintenance of 875 permanent GPS stations scheduled for completion in September 2008. PBO is currently in the fourth year of the project, with over 550 GPS stations completed to date. INGEOMINAS recently became a member of the UNAVCO consortium. UNAVCO has been working with INGEOMINAS by providing technical support for the GEORED project relating to GPS receiver specifications. In the spirit of collaboration and outreach, INGEOMINAS and UNAVCO will begin an engineer exchange program starting in early summer 2007. The purpose of this outreach program is to provide a mechanism for the exchange of ideas relating to GPS station construction techniques, hardware designs, data communications, and data archiving

  13. Kinematics to dynamics in the New Zealand plate-boundary zone

    Science.gov (United States)

    Lamb, S. H.

    2013-12-01

    New Zealand straddles the boundary between the Australian and Pacific plate, with a transition from subduction of Pacific oceanic lithosphere beneath North Island, to oblique continental collision in South Island. Cenozoic relative plate motion has resulted in a complex pattern of faulting and block rotation in a zone up to 250 km wide, with displacements on individual faults up to 100s of kilometres. Active deformation must be driven by a combination of plate-boundary forces and internal buoyancy forces. I use a compilation of seismic reflection/refraction studies and high quality receiver function analyses, together with simple Airy isostasy, to determine regional crustal and mantle structure. Integration of the vertical normal stress to the base of the deforming layer yields the buoyancy stress. Horizontal gradients of this can be compared with horizontal gradients of strain rate, using the method of England & Molnar (1997), in the context of a simple thin sheet model of deformation. Thus, if deformation is that of a Newtonian fluid, then appropriate combinations of the horizontal gradients of vorticity and dilatation are related to gradients of buoyancy stress by the fluid viscosity. However, the short term geodetic deformation is strongly biased by elastic strain accumulation related to locking on the plate interface, and cannot be used to determine the plate-boundary velocity field averaged over many seismic cycles (see Lamb & Smith 2013). Therefore, I derive here a velocity field for the plate-boundary zone, which is representative of deformation over tens of thousands of years. This is based on an inversion of fault slip, strain rate azimuth and paleomagnetic data, in the context of the short term relative plate motions, solved in a network of triangles spanning the plate-boundary, using the method of Lamb (2000). A comparison of gradients of buoyancy stress with the appropriate combinations of gradients of vorticity and dilatation shows that deformation in

  14. Spatio-temporal mapping of plate boundary faults in California using geodetic imaging

    Science.gov (United States)

    Donnellan, Andrea; Arrowsmith, Ramon; DeLong, Stephen B.

    2017-01-01

    The Pacific–North American plate boundary in California is composed of a 400-km-wide network of faults and zones of distributed deformation. Earthquakes, even large ones, can occur along individual or combinations of faults within the larger plate boundary system. While research often focuses on the primary and secondary faults, holistic study of the plate boundary is required to answer several fundamental questions. How do plate boundary motions partition across California faults? How do faults within the plate boundary interact during earthquakes? What fraction of strain accumulation is relieved aseismically and does this provide limits on fault rupture propagation? Geodetic imaging, broadly defined as measurement of crustal deformation and topography of the Earth’s surface, enables assessment of topographic characteristics and the spatio-temporal behavior of the Earth’s crust. We focus here on crustal deformation observed with continuous Global Positioning System (GPS) data and Interferometric Synthetic Aperture Radar (InSAR) from NASA’s airborne UAVSAR platform, and on high-resolution topography acquired from lidar and Structure from Motion (SfM) methods. Combined, these measurements are used to identify active structures, past ruptures, transient motions, and distribution of deformation. The observations inform estimates of the mechanical and geometric properties of faults. We discuss five areas in California as examples of different fault behavior, fault maturity and times within the earthquake cycle: the M6.0 2014 South Napa earthquake rupture, the San Jacinto fault, the creeping and locked Carrizo sections of the San Andreas fault, the Landers rupture in the Eastern California Shear Zone, and the convergence of the Eastern California Shear Zone and San Andreas fault in southern California. These examples indicate that distribution of crustal deformation can be measured using interferometric synthetic aperture radar (InSAR), Global Navigation

  15. Long-term exhumation of landscapes along the Pacific-North American plate boundary as inferred from apatite (U-Th)/He and ArcGIS analyses

    OpenAIRE

    Buscher, Jamie Todd

    2007-01-01

    The Pacific-North American plate boundary is typified by transpression and convergence, yet the relationship between interplate deformation and long-term crustal shortening is not fully understood. The continuous belt of rugged topography that extends along the entire plate boundary is generally associated with oblique tectonic plate motion, strong interplate coupling, and terrane accretion, but relating plate boundary orogenesis to variations in plate geometry and behavior requires detailed ...

  16. Effect of aseismic ridge subduction on slab geometry and overriding plate deformation: Insights from analogue modeling

    OpenAIRE

    Martinod, Joseph; Guillaume, Benjamin; Espurt, Nicolas; Faccenna, Claudio; Funiciello, Francesca; Regard, Vincent

    2013-01-01

    International audience; We present analogue models simulating the subduction of a buoyant ridge beneath an advancing overriding plate whose velocity is imposed by lateral boundary conditions. We analyze the 3D geometry of the slab, the deformation and topography of the overriding plate. Ridge subduction diminishes the dip of the slab, eventually leading to the appearance of a horizontal slab segment. This result contrasts with that obtained in free subduction experiments, in which ridge subdu...

  17. Buckling analysis of thick isotropic plates by using exponential shear deformation theory

    Directory of Open Access Journals (Sweden)

    Sayyad A. S.

    2012-12-01

    Full Text Available In this paper, an exponential shear deformation theory is presented for the buckling analysis of thick isotropic plates subjected to uniaxial and biaxial in-plane forces. The theory accounts for a parabolic distribution of the transverse shear strains across the thickness, and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. Governing equations and associated boundary conditions of the theory are obtained using the principle of virtual work. The simply supported thick isotropic square plates are considered for the detailed numerical studies. A closed form solutions for buckling analysis of square plates are obtained. Comparison studies are performed to verify the validity of the present results. The effects of aspect ratio on the critical buckling load of isotropic plates is investigated and discussed.

  18. A simplified four-unknown shear and normal deformations theory for bidirectional laminated plates

    Indian Academy of Sciences (India)

    A M Zenkour

    2015-02-01

    This paper presents a simplified 4-unknown shear and normal deformations theory for the bending analysis of cross-ply laminated plates. The present theory accounts for an adequate distribution of transverse shear strains through the plate thickness and tangential stress-free on the plate surfaces. The effect of normal strain is also included. The governing, equilibrium equations and boundary conditions are derived by employing the virtual work principle. Numerical results for stresses and displacements are compared well with those obtained using 3-D elasticity solution.

  19. A new refined theory of plates with transverse shear deformation for moderately thick and thick plates

    CERN Document Server

    Valle, Jose Miguel Martinez

    2015-01-01

    In this paper we propose a new refined shear deformation plate theory which possesses a series of desirable features, the most salient of which are as follows: (i) The loads, which are generally considered to be applied on the middle surface of the plate, act on the upper surface of the plate; (ii) The equations are applicable to the calculation of the stresses in isotropic plates and provide the same order of accuracy as several theories with second order shear deformation effects; (iii) It constitutes a theory, in the sense defined by Love, since it gives easy expressions for application to problems in different fields in architecture and civil engineering

  20. FRACTURE CALCULATION OF BENDING PLATES BY BOUNDARY COLLOCATION METHOD

    Institute of Scientific and Technical Information of China (English)

    王元汉; 伍佑伦; 余飞

    2003-01-01

    Fracture of Kirchhoff plates is analyzed by the theory of complex variables and boundary collocation method. The deflections, moments and shearing forces of the plates are assumed to be the functions of complex variables. The functions can satisfy a series of basic equations and governing conditions, such as the equilibrium equations in the domain, the boundary conditions on the crack surfaces and stress singularity at the crack tips. Thus, it ts only necessary to consider the boundary conditions on the external boundaries of the plate, which can be approximately satisfied by the collocation method and least square technique. Different boundary conditions and loading cases of the cracked plates are analyzed and calculated. Compared to other methods, the numerical examples show that the present method has many advantages such as good accuracy and less computer time This is an effective semi-analytical and semi-numerical method.

  1. Estimating area of inclusions in anisotropic plates from boundary data

    CERN Document Server

    Morassi, Antonino; Vessella, Sergio

    2011-01-01

    We consider the inverse problem of determining the possible presence of an inclusion in a thin plate by boundary measurements. The plate is made by non-homogeneous linearly elastic material belonging to a general class of anisotropy. The inclusion is made by different elastic material. Under some a priori assumptions on the unknown inclusion, we prove constructive upper and lower estimates of the area of the unknown defect in terms of an easily expressed quantity related to work, which is given in terms of measurements of a couple field applied at the boundary and of the induced transversal displacement and its normal derivative taken at the boundary of the plate.

  2. The role of the Denali fault, slab geometry, and rheology in the deformation of the overriding plate in Alaska

    Science.gov (United States)

    Jadamec, M.; Billen, M. I.; Roeske, S.

    2010-12-01

    Deformation of the North American plate in southern Alaska is characterized by uplift along the subducting plate boundary as well as a region of localized uplift in the Alaskan Range more than 500 km from the plate boundary. This interior plate deformation is spatially coincident with both the Denali Fault zone and the shallow slab in the subsurface. Whether the Denali Fault zone plays a role in localizing uplift in this region is debated and the affect of the change in slab dip on deformation of the overriding plate is also not well understood. We present 3D regional geodynamic models of the North American-Pacific plate boundary corner in southern Alaska that include the Denali fault zone modeled as a lithospheric-scale shear zone. The models include the subducting plate, overriding plate, and underlying mantle to 1500 km depth. The geometry of the subducting plate, defined from Wadati-Benioff zone seismicity and tomography, varies along the length of the Aleutian trench forming a flat slab beneath south central Alaska. The models are run with the finite-element code CitcomCU, modified to include a composite rheology (both Newtonian and non-Newtonian viscosity, as well as a depth-dependent yield stress). The models suggest the flat slab geometry beneath south central Alaska controls several first order deformation features in the overriding plate, including subsidence in the Cook Inlet Basin. To reproduce the localized uplift observed in the central Alaska Range, the models require a non-Newtonian rheology and a localized lithospheric weak zone representative of the Denali Fault, as well as the shallow slab geometry. Models with only a Newtonian viscosity do not reproduce the observed uplift, even when a localized lithospheric weak zone representative of the Denali Fault is included, indicating the importance of including the non-Newtonian mantle rheology for accurately modeling surface plate deformation.

  3. Vibration Analysis of Annular Sector Plates under Different Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Dongyan Shi

    2014-01-01

    Full Text Available An analytical framework is developed for the vibration analysis of annular sector plates with general elastic restraints along each edge of plates. Regardless of boundary conditions, the displacement solution is invariably expressed as a new form of trigonometric expansion with accelerated convergence. The expansion coefficients are treated as the generalized coordinates and determined using the Rayleigh-Ritz technique. This work allows a capability of modeling annular sector plates under a variety of boundary conditions and changing the boundary conditions as easily as modifying the material properties or dimensions of the plates. Of equal importance, the proposed approach is universally applicable to annular sector plates of any inclusion angles up to 2π. The reliability and accuracy of the current method are adequately validated through numerical examples.

  4. Relationship between outer forearc subsidence and plate boundary kinematics along the Northeast Japan convergent margin

    Science.gov (United States)

    Regalla, Christine; Fisher, Donald M.; Kirby, Eric; Furlong, Kevin P.

    2013-12-01

    Tectonic erosion along convergent plate boundaries, whereby removal of upper plate material along the subduction zone interface drives kilometer-scale outer forearc subsidence, has been purported to explain the evolution of nearly half the world's subduction margins, including part of the history of northeast Japan. Here, we evaluate the role of plate boundary dynamics in driving forearc subsidence in northeastern Japan. A synthesis of newly updated analyses of outer forearc subsidence, the timing and kinematics of upper plate deformation, and the history of plate convergence along the Japan trench demonstrate that the onset of rapid fore-arc tectonic subsidence is contemporaneous with upper plate extension during the opening of the Sea of Japan and with an acceleration in convergence rate at the trench. In Plio-Quaternary time, relative uplift of the outer forearc is contemporaneous with contraction across the arc and a decrease in plate convergence rate. The coincidence of these changes across the forearc, arc, backarc system appears to require an explanation at the scale of the entire plate boundary. Similar observations along other western Pacific margins suggest that correlations between forearc subsidence and major changes in plate kinematics are the rule, rather than the exception. We suggest that a significant component of forearc subsidence at the northeast Japan margin is not the consequence of basal tectonic erosion, but instead reflects dynamic changes in plate boundary geometry driven by temporal variations in plate kinematics. If correct, this model requires a reconsideration of the mass balance and crustal recycling of continental crust at nonaccretionary margins.

  5. Pacific plate slab pull and intraplate deformation in the early Cenozoic

    Science.gov (United States)

    Butterworth, N. P.; Müller, R. D.; Quevedo, L.; O'Connor, J. M.; Hoernle, K.; Morra, G.

    2014-08-01

    Large tectonic plates are known to be susceptible to internal deformation, leading to a~range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy-driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma, subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its northwestern perimeter, causing lithospheric extension along pre-existing weaknesses. Large-scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians volcanic ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific absolute plate motion

  6. Pacific Plate slab pull and intraplate deformation in the early Cenozoic

    Directory of Open Access Journals (Sweden)

    N. P. Butterworth

    2014-01-01

    Full Text Available Large tectonic plates are known to be susceptible to internal deformation, leading to a range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific Plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its north-western perimeter, causing lithospheric extension along pre-existing weaknesses. Large scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau, and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians Volcanic Ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific

  7. Pacific plate slab pull and intraplate deformation in the early Cenozoic

    Directory of Open Access Journals (Sweden)

    N. P. Butterworth

    2014-08-01

    Full Text Available Large tectonic plates are known to be susceptible to internal deformation, leading to a~range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy-driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma, subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its northwestern perimeter, causing lithospheric extension along pre-existing weaknesses. Large-scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians volcanic ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific

  8. Effect of aseismic ridge subduction on slab geometry and overriding plate deformation: Insights from analogue modeling

    Science.gov (United States)

    Martinod, Joseph; Guillaume, Benjamin; Espurt, Nicolas; Faccenna, Claudio; Funiciello, Francesca; Regard, Vincent

    2013-03-01

    We present analogue models simulating the subduction of a buoyant ridge oriented perpendicularly or obliquely with respect to the trench, beneath an advancing overriding plate. The convergence velocity is imposed by lateral boundary conditions in this experimental set. We analyze the three-dimensional geometry of the slab, the deformation and topography of the overriding plate. Experiments suggest that ridge subduction diminishes the dip of the slab, eventually leading to the appearance of a horizontal slab segment in case boundary conditions impose a rapid convergence. This result contrasts with that obtained in free subduction experiments, in which ridge subduction diminishes the convergence velocity which, in turn, increases the dip of the slab beneath the ridge. The slab dip decrease is accompanied by the indentation of the overriding plate by the ridge, resulting in arc curvature. Experiments suggest that indentation is larger for small convergence velocity and large slab dip. Ridge subduction also uplifts the overriding plate. Uplift first occurs close to the trench (~ fore-arc area) and is accompanied by the flexural subsidence of the overriding plate behind the uplifted area (~ back-arc subsidence). The uplifted area migrates within the overriding plate interiors following the appearance of a horizontal slab segment. These results are compared with natural examples of ridge subduction in the circum-Pacific area. They explain why ridge subduction may have contrasted effects on the overriding plate dynamics depending on the global conditions that constrain the converging system.

  9. Relations between plate kinematics, slab geometry and overriding plate deformation in subduction zones: insights from statistical observations and laboratory modelling

    Science.gov (United States)

    Heuret, A.; Funiciello, F.; Faccenna, C.; Lallemand, S.

    2005-12-01

    3-D laboratory models have been performed in order to investigate the way plates kinematics (subducting and overriding plate absolute motions and the resulting plate convergence rate) influences the geometry of the slab and the overriding plate deformation in subduction zones. In the experiments a viscous plate of silicone (subducting plate) is pushed beneath another plate, which is itself pushed toward or pulled away from the trench (overriding plate), and sinks into a viscous layer of glucose syrup (upper mantle). The subducting and overriding plate velocities explored the variability field of natural subduction plates kinematics. The overriding plate motion exerts a primary role in the control of slab geometries and overriding plate deformation rates. The experiments have revealed two different subduction behaviours: (Style I) the overriding plate moves toward the trench and shortens at high rates, the slab is flat and deflected when reaching the bottom of the box in a forward direction; (Style II) the overriding plates moves away from the trench and shortens at low rates the slab is steep and deflected on the box bottom in a backward direction. To a lesser extent, increasing subducting plate motion is associated to increasing slab dips and overriding plate shortening. Slab geometry and overriding plate deformation are less sensitive to the overall plate convergence rate. These laboratory models behaviours are consistent with statistical analysis performed on natural subduction zones, and enlighten the first order control exerted by the overriding plate absolute motion, on the geometry adopted by the slab and the way the overriding plate deforms.

  10. Free Vibration of Embedded Porous Plate Using Third-Order Shear Deformation and Poroelasticity Theories

    Directory of Open Access Journals (Sweden)

    Ali Ghorbanpour Arani

    2017-01-01

    Full Text Available This research aims at studying free vibration of rectangular plate made of porous materials in which Y-foam, G-foam, and Coustone are used and compared with each other. To obtain the Biot formulation of the constitutive equations for a porous material, linear poroelasticity theory is used. Young modulus and density of porous plate are different in transverse direction versus porosity. In order to increase the accuracy of results in comparison with classical plate and first-order shear deformation theories, Reddy’s theory was utilized in this research. Besides, five coupled equations of motion have been studied using Hamilton’s principle and are solved by differential quadrature method (DQM. Detailed results of this study show the significant effect of aspect ratio, thickness ratio, boundary conditions, and porosity on dimensionless frequency and deflection of porous plate. Results of this study can contribute to the design of pneumatic conveying, handling, and control systems.

  11. Significance of broad scale deformation of incoming plates at ocean trenches.

    Science.gov (United States)

    Ranero, C. R.; Calahorrano, A.; Grevemeyer, I.; Barckhausen, U.; Reichert, C. J.

    2012-12-01

    Recent seismic experiments in several ocean trenches indicate that oceanic lithosphere undergoes profound chemical changes due to percolation of water into the mantle along faults formed by bending-related deformation. When compared to earthquake activity the depth of mantle alteration seems to be related to the elastic thickness of the plate and thus controlled by bending stresses. This finding contrasts with previous speculation that large-great trench-outer-rise earthquakes were important in the formation of paths for water penetration into the plate. Large-great trench-outer-rise earthquakes are probably related to slab pull during decoupling along the interplate boundary and not necessarily controlled by bending stresses. Thus, current findings may seem to indicate that plate age and related elastic thickness at trenches may be be the key parameter that controls the amount of hydration that may occur in a plate. New multichannel seismic reflection images from northern Chile and a compilation of multibeam bathymetry display a remarkable variability of bending-related deformation along several hundreds kilometres of the subduction zone where plate age does not change significantly indicating that deformation and probably hydration might be very variable in space. A set of seismic profiles collected perpendicular to the trench and running several hundreds of kilometers into the incoming plate show that the bending-related deformation of the oceanic plate reaches the mantle well before the lithosphere plunges into the trench and develops a marked bend-faulting fabric observable in bathymetric maps. Similar conclusions can be reached from seismic images across the outer rise of the Cocos plate entering the Middle America Trench. Also, the combination of seismic images and swath bathymetry along the Chile trench shows a remarkable lateral variability in the intensity and style of deformation at the trench. The deformation appears to be controlled by the stresses

  12. Evolution of fuel plate parameters during deformation in rolling

    Science.gov (United States)

    Durazzo, M.; Vieira, E.; Urano de Carvalho, E. F.; Riella, H. G.

    2017-07-01

    The Nuclear and Energy Research Institute - IPEN/CNEN-SP routinely produces the nuclear fuel necessary for operating its research reactor, IEA-R1. This fuel consists of fuel plates containing U3Si2-Al composites as the meat, which are fabricated by rolling. The rolling process currently deployed was developed based on information obtained from literature, which was used as a premise for defining the current manufacturing procedures, according to a methodology with an essentially empirical character. Despite the current rolling process being perfectly stable and highly reproducible, it is not well characterized and is therefore not fully known. The objective of this work is to characterize the rolling process for producing dispersion fuel plates. Results regarding the evolution of the main parameters of technological interest, after each rolling pass, are presented. Some defects that originated along the fuel plate deformation during the rolling process were characterized and discussed. The fabrication procedures for manufacturing the fuel plates are also presented.

  13. Extending Alaska's plate boundary: tectonic tremor generated by Yakutat subduction

    Science.gov (United States)

    Wech, Aaron G.

    2016-01-01

    The tectonics of the eastern end of the Alaska-Aleutian subduction zone are complicated by the inclusion of the Yakutat microplate, which is colliding into and subducting beneath continental North America at near-Pacific-plate rates. The interaction among these plates at depth is not well understood, and further east, even less is known about the plate boundary or the source of Wrangell volcanism. The drop-off in Wadati-Benioff zone (WBZ) seismicity could signal the end of the plate boundary, the start of aseismic subduction, or a tear in the downgoing plate. Further compounding the issue is the possible presence of the Wrangell slab, which is faintly outlined by an anemic, eastward-dipping WBZ beneath the Wrangell volcanoes. In this study, I performed a search for tectonic tremor to map slow, plate-boundary slip in south-central Alaska. I identified ∼11,000 tremor epicenters, which continue 85 km east of the inferred Pacific plate edge marked by WBZ seismicity. The tremor zone coincides with the edges of the downgoing Yakutat terrane, and tremors transition from periodic to continuous behavior as they near the aseismic Wrangell slab. I interpret tremor to mark slow, semicontinuous slip occurring at the interface between the Yakutat and North America plates. The slow slip region lengthens the megathrust interface beyond the WBZ and may provide evidence for a connection between the Yakutat slab and the aseismic Wrangell slab.

  14. Novel boundary element method for resolving plate bending problems

    Institute of Scientific and Technical Information of China (English)

    陈颂英; 王乐勤; 焦磊

    2003-01-01

    This paper discusses the application of the boundary contour method for resolving plate bending problems. The exploitation of the integrand divergence free property of the plate bending boundary integral equation based on the Kirchhoff hypothesis and a very useful application of Stokes' Theorem are presented to convert surface integrals on boundary elements to the computation of bending potential functions on the discretized boundary points, even for curved surface elements of arbitrary shape. Singularity and treatment of the discontinued corner point are not needed at all. The evaluation of the physics variant at internal points is also shown in this article. Numerical results are presented for some plate bending problems and compared against analytical and previous solutions.

  15. Geodetic observations in Iceland: divergent plate boundary influenced by a hotspot

    Science.gov (United States)

    Ofeigsson, Benedikt Gunnar; Hreinsdóttir, Sigrun; Sigmundsson, Freysteinn; Arnadottir, Thora; Vogfjord, Kristin; Geirsson, Halldor; Einarsson, Pall; Jonsson, Sigurjon; Villemin, Thierry; Fjalar Sigurdsson, Sigurdur; Roberts, Matthew; Sturkell, Erik; Lafemina, Peter C.; Bennett, Richard; Voelksen, Christof; Valsson, Gudmundur; Sigurdsson, Thorarinn

    2013-04-01

    The mid Atlantic ridge, separating the Eurasian and North American tectonic plates, is mostly buried below the Atlantic. There are, however, a few places where subaerial exposure of the mid-oceanic rift system allows geodetic observations of the deformation associated with the plate boundary. Iceland is the largest portion of the system emerged above sea level, a consequence of excessive volcanism caused by the interaction of a mantle plume with the mid-oceanic ridge. Iceland is therefore a unique site to study processes associated with divergent plate boundaries, and the effects of the plume-ridge interaction. A network of continuous GPS stations have been operating in Iceland since 1995 when the first station was installed in Reykjavik. Since then, stations have been added to the network at different points in time, with over 70 stations presently in operation. The network has been used e.g. for studies of deformation associated with the divergent plate boundary, micro-plate formation due to rift jumps, the plate-spreading deformation cycle associated with rifting episodes, strain rates and stress accumulation on transform zones connecting the ridge segments and deformation due to magmatic processes. In addition the GPS network is used in studies of the deformation associated with mass variations of Iceland's glaciers. The continuous GPS network serves as monitoring tool in Iceland, both for volcanic and seismic hazards but also as a research tool. In the recent Futurvolc project, which partly builds on EPOS, the data from the continuous GPS network along with data from the seismic network and InSAR observations, will serve as the main input in joint analyses of long and short term magma movements in volcanic regions. The establishment of the continuous GPS network in Iceland has provided an ideal tool to further increase our understanding of the geodynamic processes associated with divergent plate boundaries and plume-ridge interaction as well as establishing a

  16. Scientific Advances from Paul Silver's Inspirational Leadership of the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Miller, M. M.; Calais, E.; Jackson, M. E.; Owen, S. E.; Segall, P.

    2009-12-01

    While major scientific endeavors and advances rely on the work and dedication of many, they are often made possible thanks to the passion and clear vision articulated by one or two leading scientists. Paul Silver was that leading visionary for EarthScope’s Plate Boundary Observatory. Paul Silver understood early on that the synergy of seismic and geodetic observations contained fundamental information on the coupled lithosphere-mantle system, the key to cracking the dynamics that underlies plate tectonics and continental deformation. This became a central theme of the Earthscope initiative, and Paul, a seismologist by training, became a tireless advocate for geodesy at all stages of the project - and for instrumentation over the broadest possible temporal bandwidth, from GPS geodesy to strainmeters. The presentation, given on behalf of UNAVCO and the UNAVCO community, will review and honor Paul's contributions to UNAVCO and the Plate Boundary Observatory science.

  17. Plate boundaries in the Woodlark Basin and Solomon Sea Region, Papua New Guinea

    Science.gov (United States)

    Goodliffe, A. M.; Cameron, M.

    2009-12-01

    The Solomon Sea and Woodlark Basin region of eastern Papua New Guinea is a tectonically complex region between the obliquely converging Pacific and Australian plates. Despite numerous marine geophysical surveys in the region, the exact nature of the tectonic boundaries between the Solomon Sea and the Woodlark Basin remains controversial. Marine geophysical data collected in the last decade provides additional insight into this region and clearly defines the boundaries of the Solomon Sea, Trobriand, Woodlark, and Australian plates. Multibeam bathymetry data collected in 2004 along the Trobriand Trough, together with seismic profiles across the trough, show a prominent deformation front in the trench that defines the southern boundary of the Solomon Sea plate. Petrologic data from volcanoes to the south of this boundary indicate that they have a subduction affinity. Heat flow profiles to the south of the plate boundary show a clear subduction signature. At the eastern termination of the Trobriand Trough the plate boundary forms a triple junction with the NE-SW trending Nubaru strike-slip fault. To the NE this major fault separates the Solomon Sea plate from the Woodlark plate. The morphology of this fault and a CMT solution indicate that it is right-lateral. To the SW the Nubaru strike-slip fault passes to the south of the Trobriand Trough, forming the southern boundary of the Trobriand plate (with the Trobriand Trough as the northern boundary). Further west the trend of the strike slip fault becomes more ENE-WSW. A significant extension component is evident as the fault passes to the north of Egum Graben and meets the Woodlark Basin spreading system at the current rifting to seafloor spreading transition directly to the east of Moresby Seamount. The revised tectonic model for this region has important implications for tectonic reconstructions that include an active rifting to spreading transition and prominent core complexes. In the past, models have assumed a

  18. Inverse transient thermoelastic deformations in thin circular plates

    Indian Academy of Sciences (India)

    A K Tikhe; K C Deshmukh

    2005-10-01

    This paper deals with the determination of unknown heating temperatures and temperature distributions on the upper surface of a thin circular plate, defined as $0 \\leq r \\leq a,−b/2 \\leq z \\leq b/2$. The expressions of unknown heating temperatures and temperature distributions are obtained in series form, involving Bessel’s functions with the help of the integral transform technique. Thermoelastic deformations are discussed with the help of temperature and are illustrated numerically.

  19. Plate boundary forces in the vicinity of Trinidad-the-transition from transpression to transtension in the Southern Caribbean plate boundary zones

    Energy Technology Data Exchange (ETDEWEB)

    Algar, S.T.; Pindell, J.L. (Dartmouth College, Hanover, NH (United States))

    1993-02-01

    Deformation in the southern Caribbean plate boundary zones as recorded in the Northern Range of Trinidad initiated in the Oligocene with northward vergent gravity sliding of Northern Range sediments due to uplift and oversteepening of the previously passive margin by the eastward migration of the Caribbean flexural forebulge. Progressive east-southeast transvergence of the Caribbean Plate with respect to South America overthrust incorporated the Northern Range sediments into the Caribbean accretionary prism, thrusting them south-southeast to produce a Middle Miocene transpressive foreland fold and thrust belt in southern Trinidad. Late Miocene deformation within Trinidad was increasingly dominated by right-lateral strike-slop (RLSS) faulting, at the expense of transpressive compressional features. Right-stepping of RLSS motion initiated the Gulf of Paria and Caroni pull-apart basins, Since Early Pliocene these basins and other areas to the north of Trinidad have undergone north-south extension in addition to east-west trending RLSS. Such extension caused the northward withdrawal of Caribbean terranes from atop of the Northern Range, Resulting in rapid isostatically induced uplift (approximately 0.5 mmyr[sup -1]). This change in deformation style may relate to a hitherto unrecognized shift in the relative motion of the eastern Caribbean Plate with respect to South America: from east-southeast-directed transpression to east-northeast-directed transtension.

  20. Quantitative Microstructural Characterization of Thick Aluminum Plates Heavily Deformed Using Equal Channel Angular Extrusion

    DEFF Research Database (Denmark)

    Mishin, Oleg; Segal, V.M.; Ferrasse, S.

    2012-01-01

    deg rotations about the longitudinal axis. Statistically robust data were obtained in this work using gallium enhanced microscopy and EBSD mapping of large sample areas. For the plate processed using route A, the fraction of high-angle boundaries was found to strongly depend on the inspection plane......A detailed quantitative analysis of the microstructure has been performed in three orthogonal planes of 15-mm-thick aluminum plates heavily deformed via two equal channel angular extrusion (ECAE) routes. One route was a conventional route A with no rotation between passes. Another route involved...... sequential 90 deg rotations about the normal direction (ND) between passes. The microstructure in the center of these plates, and especially the extent of microstructural heterogeneity, has been characterized quantitatively and compared with that in bar samples extruded via either route A or route Bc with 90...

  1. Numerical models on thermal and rheological sensitivity of deformation pattern at the lithosphere-asthenosphere boundary

    Science.gov (United States)

    Fuchs, Lukas; Schmeling, Harro; Koyi, Hemin

    2014-05-01

    Understanding the interaction between the oceanic lithosphere and the upper mantle is a crucial part in understanding plate tectonics/kinematic, especially along the lithosphere-asthenosphere boundary (LAB). In this study, we analyzed finite deformation (f = log(a b) , where a and b are the major and minor axis of the strain ellipse, respectively) integrated over time, within the upper 400 km of the mantle. The velocity field was numerically calculated within a two-dimensional channel of certain depth and length with a constant plate velocity on top (Couette flow), with no slip bottom boundary and open side boundaries. The viscosity is described by a composite rheology (dislocation and diffusion creep) which is given by a temperature field based on a half-space cooling model for an oceanic lithospheric plate using variable thermal parameters. A constant pressure was applied at the left boundary of the channel to obtain a faster flowing asthenosphere (additional Poiseuille flow). The depth of the LAB is assumed to be mechanically defined and corresponds to the depth at which no additional strain is accumulated on the downstream side, separating the high-viscous non-deforming lithosphere from the low-viscous asthenosphere. Model results show that the lower part of the lithosphere defined in this way is characterized by large inherited strains (f ~ 2). Due to the applied kinematic boundary conditions for a Couette-flow model and the lateral viscosity variations within the channel a minor induced Poiseuille-flow component is obtained within the model. Thus, the stresses vary significantly in comparison to the 1D solution of a Couette-flow. Preliminary results show that deformation along the LAB is strongly governed by the temperature and the plate velocity. The maximum depth of the lithosphere defined in the above way is 120 km, and correlates with the 1230 °C temperature contour line. Moreover, assuming steady state, the finite deformation will always increase with

  2. A paleomagnetic investigation of vertical-axis rotations in coastal Sonora, Mexico: Evidence for distributed transtensional deformation during the Proto-Gulf shift from a subduction-dominated to transform-dominated plate boundary in the Gulf of California

    Science.gov (United States)

    Herman, Scott William

    The history of late Miocene (Proto-Gulf) deformation on the Sonoran margin of the Gulf of California is key to understanding how Baja California was captured by the Pacific plate and how strain was partitioned during the Proto-Gulf period (12.5-6 Ma). The Sierra el Aguaje and Sierra Tinajas del Carmen are located in southwestern coastal Sonora, Mexico, and represent the eastern rifted margin of the central Gulf of California. The ranges are composed of volcanic units and their corresponding volcaniclastic units which are the result of persistent magmatic activity between 20 and 8.8 Ma, including three packages of basalt and andesite that make excellent paleomagnetic recorders. Based on cross cutting relations and geochronologic data for pre-, syn-, and post-tectonic volcanic units, most of the faulting and tilting in the Sierra El Aguaje is bracketed between 11.9 and 9.0 Ma, thus falling entirely within Proto-Gulf time. A paleomagnetic investigation into possible vertical axis rotations in the Sierra el Aguaje has uncovered evidence of clockwise rotations between ~13º and ~105º with possible translations. These results are consistent with existing field relations, which suggest the presence of large (>45°) vertical axis rotations in this region. This evidence includes: a) abrupt changes in the strike of tilted strata in different parts of the range, including large domains characterized by E-W strikes b) ubiquitous NE-SW striking faults with left lateral-normal oblique slip, that terminate against major NW-trending right lateral faults, and c) obliquity between the general strike of tilted strata and the strike of faults. These rotations occurred after 12 Ma and largely prior to 9 Ma, thus falling into the Proto-Gulf period. Such large-scale rotations lend credence to the theory that the area inboard of Baja California was experiencing transtension during the Proto-Gulf period, rather than the pure extension that would be the result of strain partitioning

  3. Deformation of a layered magnetoelectroelastic simply-supported plate with nonlocal effect, an analytical three-dimensional solution

    Science.gov (United States)

    Pan, Ernian; Waksmanski, Natalie

    2016-09-01

    In this paper, we present an exact closed-form solution for the three-dimensional deformation of a layered magnetoelectroelastic simply-supported plate with the nonlocal effect. The solution is achieved by making use of the pseudo-Stroh formalism and propagator matrix method. Our solution shows, for the first time, that for a homogeneous plate with traction boundary condition applied on its top or bottom surface, the induced stresses are independent of the nonlocal length whilst the displacements increase with increasing nonlocal length. Under displacement boundary condition over a homogeneous or layered plate, all the induced displacements and stresses are functions of the nonlocal length. Our solution further shows that regardless of the Kirchoff or Mindlin plate model, the error of the transverse displacements between the thin plate theory and the three-dimensional solution increases with increasing nonlocal length revealing an important feature for careful application of the thin plate theories towards the problem with nonlocal effect. Various other numerical examples are presented for the extended displacements and stresses in homogeneous elastic plate, piezoelectric plate, magnetostrictive plate, and in sandwich plates made of piezoelectric and magnetostrictive materials. These results should be very useful as benchmarks for future development of approximation plate theories and numerical modeling and simulation with nonlocal effect.

  4. Deformation of Honeycomb with Finite Boundary Subjected to Uniaxial Compression

    Directory of Open Access Journals (Sweden)

    Dai-Heng Chen

    2013-11-01

    Full Text Available In this paper, the crushing behavior of hexagonal honeycomb structures with finite boundaries (finite width and height subjected to in-plane uniaxial compressive loading is studied based on the nonlinear finite element analysis. It is found that stress-strain responses for the honeycombs with finite boundaries can be classified into two types: Type I and Type II. Such a characteristic is affected by the wall thickness, the work-hardening coefficient and the yield stress for the honeycombs. Furthermore, a transition from the symmetric to asymmetric deformation mode can be observed in Type I, and these deformed cells were localized in a horizontal layer. However, for the case of Type II response, the symmetric and asymmetric deformation modes can be observed simultaneously, and the region of the asymmetric mode was formed by the cell layer along the diagonal direction. As a result, the shear deformation behavior was developed along that direction. Moreover, the effect of work-hardening on the deformation behavior for the honeycombs with finite boundaries can be explained from that for infinite honeycombs.

  5. Structural vibration a uniform accurate solution for laminated beams, plates and shells with general boundary conditions

    CERN Document Server

    Jin, Guoyong; Su, Zhu

    2015-01-01

    This book develops a uniform accurate method which is capable of dealing with vibrations of laminated beams, plates and shells with arbitrary boundary conditions including classical boundaries, elastic supports and their combinations. It also provides numerous solutions for various configurations including various boundary conditions, laminated schemes, geometry and material parameters, which fill certain gaps in this area of reach and may serve as benchmark solutions for the readers. For each case, corresponding fundamental equations in the framework of classical and shear deformation theory are developed. Following the fundamental equations, numerous free vibration results are presented for various configurations including different boundary conditions, laminated sequences and geometry and material properties. The proposed method and corresponding formulations can be readily extended to static analysis.

  6. Swath sonar mapping of Earth's submarine plate boundaries

    Science.gov (United States)

    Carbotte, S. M.; Ferrini, V. L.; Celnick, M.; Nitsche, F. O.; Ryan, W. B. F.

    2014-12-01

    The recent loss of Malaysia Airlines flight MH370 in an area of the Indian Ocean where less than 5% of the seafloor is mapped with depth sounding data (Smith and Marks, EOS 2014) highlights the striking lack of detailed knowledge of the topography of the seabed for much of the worlds' oceans. Advances in swath sonar mapping technology over the past 30 years have led to dramatic improvements in our capability to map the seabed. However, the oceans are vast and only an estimated 10% of the seafloor has been mapped with these systems. Furthermore, the available coverage is highly heterogeneous and focused within areas of national strategic priority and community scientific interest. The major plate boundaries that encircle the globe, most of which are located in the submarine environment, have been a significant focus of marine geoscience research since the advent of swath sonar mapping. While the location of these plate boundaries are well defined from satellite-derived bathymetry, significant regions remain unmapped at the high-resolutions provided by swath sonars and that are needed to study active volcanic and tectonic plate boundary processes. Within the plate interiors, some fossil plate boundary zones, major hotspot volcanoes, and other volcanic provinces have been the focus of dedicated research programs. Away from these major tectonic structures, swath mapping coverage is limited to sparse ocean transit lines which often reveal previously unknown deep-sea channels and other little studied sedimentary structures not resolvable in existing low-resolution global compilations, highlighting the value of these data even in the tectonically quiet plate interiors. Here, we give an overview of multibeam swath sonar mapping of the major plate boundaries of the globe as extracted from public archives. Significant quantities of swath sonar data acquired from deep-sea regions are in restricted-access international archives. Open access to more of these data sets would

  7. Shear deformation plate continua of large double layered space structures

    Science.gov (United States)

    Hefzy, Mohamed Samir; Nayfeh, Adnan H.

    1986-01-01

    A simple method is presented to model large rigid-jointed lattice structures as continuous elastic media with couple stresses using energy equivalence. In the analysis, the transition from the discrete system to the continuous media is achieved by expanding the displacements and the rotations of the nodal points in a Taylor series about a suitable chosen origin. The strain energy of the continuous media with couple stresses is then specialized to obtain shear deformation plate continua. Equivalent continua for single layered grids, double layered grids, and three-dimensional lattices are then obtained.

  8. Geodynamic Evolution of the Nubia-Arabia-Somalia Plate Boundary System

    Science.gov (United States)

    Reilinger, R. E.; McClusky, S.; Vernant, P.; Ogubazghi, G.; Fisseha, S.; Arrajehi, A.; Bendick, R. O.; Sholan, J.

    2009-12-01

    We present a geodynamic scenario for the evolution of the Nubia (Nu)-Arabia (Ar)-Somalia (So) plate boundary system that is based on new geodetic constraints on the kinematics of active deformation, and published estimates of the timing of regional tectonic processes. This scenario supports two, long debated, principal hypotheses for plate dynamics, 1) plate motions are driven primarily by sinking of oceanic lithosphere at subduction zones, and 2) the lithosphere is strong in relation to plate boundaries and drag forces on the base of the lithosphere (and likely, resisting forces associate with continental collision). 1) During the Late Oligocene (~30 Ma), domal uplift of the Afar region due to the Afar hot spot caused regional extension and the initial development of the Afar Triple Junction (TJ) along pre-existing zones of weakness; 2) The So-Nu plate boundary, East African Rift (EAR), developed at a slow rate due to the absence of boundary-normal extensional stresses (i.e., no subduction “pulling” the So Plate), slow motion that continues to the present; 3) Larger extensional stresses across the Nu-Ar and Ar-So boundaries (Red Sea and Gulf of Aden) due to active subduction of the Neotethys ocean lithosphere beneath Eu caused more rapid extension of these early rifts, with full scale continental rifting beginning ~ 25-30 Ma; 4) Between 16 - 11 Ma full ocean rifting in the Gulf of Aden caused a decrease in the forces transmitted to the So and Nu plates, causing slowing of the Nu and So plates with respect to Eu and Ar, and (possibly) an additional component of N-S oriented extension across the Red Sea; 5) Around this time (~10 Ma), activity shifted from the Gulf of Suez to the DSF system in the N Red Sea, and the Danakil Block in the southern Red Sea began rotating with respect to Nu and Ar, both changes related to the change in Nu-Ar relative motion; and 6) The balance of forces on the plate system have remained roughly unchanged since ~10 Ma, as have

  9. Numerical simulation of the collision between Indian and Eurasian Plates and the deformations of the present Chinese continent

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper the continental lithosphere of the East Asia is regarded as a continuum in a power law rheology. It lays on a relative soft upper mantle and limited in a trapezoid geological frame. The movement of the Indian Plate at the rate of 5 cm/a is assumed to be the main driving force for the Tibet Plateau(s uplift and the lithosphere deformation of the Chinese continent. The numerical simulation shows that the predicted horizontal deformation model of the Chinese continent is comparable with the results of the GPS observation. It implicates that the collision and compression between India and Eurasia Plates is the main driving force of the horizontal deformations of the Chinese continent. It is also shows that the patterns of the continental deformation are controlled by many factors such as the dynamical parameters of the lithosphere and the boundary conditions as well.

  10. Locking, mass flux and topographic response at convergent plate boundaries - the Chilean case

    Science.gov (United States)

    Oncken, Onno

    2016-04-01

    On the long term, convergent plate boundaries have been shown to be controlled by either accretion/underplating or by subduction erosion. Vertical surface motion is coupled to convergence rate - typically with an uplift rate of the coastal area ranging from 0 to +50% of convergence rate in accretive systems, and -20 to +30% in erosive systems. Vertical kinematics, however, are not necessarily linked to horizontal strain mode, i.e. upper plate shortening or extension, in a simple way. This range of kinematic behaviors - as well as their acceleration where forearcs collide with oceanic ridges/plateau - is well expressed along the Chilean plate margin. Towards the short end of the time scale, deformation appears to exhibit a close correlation with the frictional properties and geodetic locking at the plate interface. Corroborating analogue experiments of strain accumulation during multiple earthquake cycles, forearc deformation and uplift focus above the downdip and updip end of seismic coupling and slip and are each related to a particular stage of the seismic cycle, but with opposite trends for both domains. Similarly, barriers separating locked domains along strike appear to accumulate most upper plate faulting interseismically. Hence, locking patters are reflected in topography. From the long-term memory contained in the forearc topography the relief of the Chilean forearc seems to reflect long term stability of the observed heterogeneity of locking at the plate interface. This has fundamental implications for spatial and temporal distribution of seismic hazard. Finally, the nature of locking at the plate interface controlling the above kinematic behavior appears to be strongly controlled by the degree of fluid overpressuring at the plate interface suggesting that the hydraulic system at the interface takes a key role for the forearc response.

  11. The Plate Boundary Observatory: Data Management Progress and Highlights

    Science.gov (United States)

    Anderson, G.; Blackman, B.; Eakins, J.; Hodgkinson, K.; Matykiewicz, J.; Boler, F.; Beldyk, M.; Henderson, B.; Hoyt, B.; Lee, E.; Persson, E.; Smith, J.; Torrez, D.; Wright, J.; Jackson, M.; Meertens, C.

    2007-12-01

    The Plate Boundary Observatory (PBO), part of the NSF-funded EarthScope project, is designed to study the three- dimensional strain field resulting from deformation across the active boundary zone between the Pacific and North American plates in the western United States. To meet these goals, UNAVCO will install 880 continuous GPS stations, 103 borehole strainmeter stations, 28 tiltmeters, and five laser strainmeters by October 2008, as well as manage data for 209 previously existing continuous GPS stations and one laser strainmeter through the PBO Nucleus project and 11 GPS stations installed by the USArray segment of EarthScope. As of 1 September 2007, UNAVCO had completed 680 PBO GPS stations and had upgraded 89% of the planned PBO Nucleus stations. Most of these stations return data to the UNAVCO Boulder Network Operations Center (NOC) on a daily basis, with about 40 stations returning data on an hourly basis. Overall, the combined PBO and Nucleus network has now provided almost 350 GB of raw standard rate data, which are routinely processed by the PBO GPS Analysis Centers, at Central Washington University and the New Mexico Institute of Mining and Technology, and the PBO GPS Analysis Center Coordinator at MIT. These groups create a range of GPS products, including station position time series, GPS velocity vectors, and related information. As of September 2007, these centers processed data on a daily basis from about 920 stations; typical position uncertainties are under 1.5 mm horizontally and 4 mm vertically. All PBO GPS data products are archived at and available from the UNAVCO Facility, with a second archive at the IRIS Data Management Center (DMC). All these products may be accessed via the PBO web page at http://pboweb.unavco.org/gps_data. As part of PBO, UNAVCO will also install and operate the largest borehole seismic and strainmeter networks in North America, as well as tiltmeters and laser strainmeters. As of September 2007, 41 PBO borehole stations

  12. Free, transverse vibrations of thin plates with discontinuous boundary conditions

    Science.gov (United States)

    Febbo, M.; Vera, S. A.; Laura, P. A. A.

    2005-03-01

    Vibrations of circular and rectangular plates clamped on part of the boundary and simply supported along the remainder are analyzed by means of a method of perturbation of boundary conditions. This approach appears to be simple and straightforward, giving excellent results for the first mode and its versatility permits to extend it to higher modes of vibration without difficulty. Furthermore, it is shown that the fundamental frequency coefficient can also be determined using a modified Galerkin approach and very simple polynomial coordinate functions which yield good engineering accuracy.

  13. Slip systems, dislocation boundaries and lattice rotations in deformed metals

    DEFF Research Database (Denmark)

    Winther, Grethe

    2009-01-01

    strains at room temperature are analysed. A major result is that, by contrast to previous beliefs, the boundaries align with specific crystallographic planes, which depend on the crystallographic grain orientation. This grain orientation dependence originates from an underlying dependence of the active...... of the mechanical anisotropy of rolled sheets. The rotation of the crystallographic lattice in each grain during deformation also exhibits grain orientation dependence, originating from the slip systems. A combined analysis of dislocation boundaries and lattice rotations concludes that the two phenomena are coupled...

  14. Global plate boundary evolution and kinematics since the late Paleozoic

    Science.gov (United States)

    Matthews, Kara J.; Maloney, Kayla T.; Zahirovic, Sabin; Williams, Simon E.; Seton, Maria; Müller, R. Dietmar

    2016-11-01

    Many aspects of deep-time Earth System models, including mantle convection, paleoclimatology, paleobiogeography and the deep Earth carbon cycle, require high-resolution plate motion models that include the evolution of the mosaic of plate boundaries through time. We present the first continuous late Paleozoic to present-day global plate model with evolving plate boundaries, building on and extending two previously published models for the late Paleozoic (410-250 Ma) and Mesozoic-Cenozoic (230-0 Ma). We ensure continuity during the 250-230 Ma transition period between the two models, update the absolute reference frame of the Mesozoic-Cenozoic model and add a new Paleozoic reconstruction for the Baltica-derived Alexander Terrane, now accreted to western North America. This 410-0 Ma open access model provides a framework for deep-time whole Earth modelling and acts as a base for future extensions and refinement. We analyse the model in terms of the number of plates, predicted plate size distribution, plate and continental root mean square (RMS) speeds, plate velocities and trench migration through time. Overall model trends share many similarities to those for recent times, which we use as a first order benchmark against which to compare the model and identify targets for future model refinement. Except for during the period 260-160 Ma, the number of plates (16-46) and ratio of "large" plates (≥ 107.5 km2) to smaller plates ( 2.7-6.6) are fairly similar to present-day values (46 and 6.6, respectively), with lower values occurring during late Paleozoic assembly and growth of Pangea. This temporal pattern may also reflect difficulties in reconstructing small, now subducted oceanic plates further back in time, as well as whether a supercontinent is assembling or breaking up. During the 260-160 Ma timeframe the model reaches a minima in the number of plates, in contrast to what we would expect during initial Pangea breakup and thus highlighting the need for refinement

  15. Tectonics of the Nazca-Antarctic plate boundary

    Science.gov (United States)

    Anderson-Fontana, Sandra; Larson, Roger L.; Engeln, Joseph F.; Lundgren, Paul; Stein, Seth

    1987-01-01

    A new bathymetric chart of part of the Chile transform system is constructed, based mainly on an R/V Endeavor survey from 100 deg W to its intersection with the East Ridge of the Juan Fernandez microplate. A generally continuous lineated trend can be followed through the entire region, with the transform valley being relatively narrow and well-defined from 109 deg W to approximately 104 deg 30 min W. The fracture zone then widens to the east, with at least two probable en echelon offsets to the south at 104 deg and 102 deg W. Six new strike-slip mechanisms along the Chile Transform and one normal fault mechanism near the northern end of the Chile Rise, inverted together with other plate-motion data from the eastern portion of the boundary, produce a new best-fit Euler pole for the Nazca-Antarctic plate pair, providing tighter constraints on the relative plate motions.

  16. Tectonics of the Nazca-Antarctic plate boundary

    Science.gov (United States)

    Anderson-Fontana, Sandra; Larson, Roger L.; Engeln, Joseph F.; Lundgren, Paul; Stein, Seth

    1987-01-01

    A new bathymetric chart of part of the Chile transform system is constructed, based mainly on an R/V Endeavor survey from 100 deg W to its intersection with the East Ridge of the Juan Fernandez microplate. A generally continuous lineated trend can be followed through the entire region, with the transform valley being relatively narrow and well-defined from 109 deg W to approximately 104 deg 30 min W. The fracture zone then widens to the east, with at least two probable en echelon offsets to the south at 104 deg and 102 deg W. Six new strike-slip mechanisms along the Chile Transform and one normal fault mechanism near the northern end of the Chile Rise, inverted together with other plate-motion data from the eastern portion of the boundary, produce a new best-fit Euler pole for the Nazca-Antarctic plate pair, providing tighter constraints on the relative plate motions.

  17. Geodetic and tectonic analyses along an active plate boundary: The central Gulf of California

    Science.gov (United States)

    Ortlieb, L.; Ruegg, J. C.; Angelier, J.; Colletta, B.; Kasser, M.; Lesage, P.

    1989-06-01

    The Gulf of California is traversed by the shear plate boundary between Pacific and North American plates and, because of several islands in its central part, offers the possibility of direct geodetic measurements of plate motion. A geodetic network of 150 km aperture, and comprising 11 stations, was measured in 1982 and 1986 by laser trilateration methods. The deformations deduced from the comparison of the two epochs indicate right-lateral shear strain covering the entire gulf rather than localized movements. In the eastern part of the network, between the axial islands and the Sonoran coast, significant right-lateral shear deformation occurs with a relative displacement of about 23 ± 12 cm over 4 years. In the northwestern region (Canal de Ballenas) a right-lateral displacement of about 17 ± 4 cm is observed, whereas in the southwestern part of the network (Canal Sal-si-Puedes), the deformation remains very weak. This suggests that south of the Canal de Ballenas the plate boundary is locked. A tectonic analysis of Neogene and Quaternary faults in Baja California, Sonora, and the central islands of the gulf, permitted the reconstruction of the stress pattern evolution of this area. These data also indicate the predominance of right-lateral motion on a NW-SE trending zone within a regional framework characterized by an approximately N-S compression and an E-W extension. The geodetic results are discussed in comparison with the neotectonic analysis and the seismic data available in the area. The data suggest a broad strain accumulation zone covering the totality of the central Gulf of California. A NW-SE relative velocity of about 8 ± 3 cm/yr is found between the two sides of the gulf during the 1982-1986 interval.

  18. A Boundary Element Method for Simulation of Deformable Objects

    Institute of Scientific and Technical Information of China (English)

    徐美和; 唐泽圣

    1996-01-01

    In this paper,a boundary element method is first applied to real-tim animation of deformable objects and to simplify data preparation.Next,the visibleexternal surface of the object in deforming process is represented by B-spline surface,whose control points are embedded in dynamic equations of BEM.Fi-nally,the above method is applied to anatomical simulation.A pituitary model in human brain,which is reconstructed from a set of anatomical sections, is selected to be the deformable object under action of virtual tool such as scapel or probe.It produces fair graphic realism and high speed performance.The results show that BEM not only has less computational expense than FEM,but also is convenient to combine with the 3D reconstruction and surface modeling as it enables the reduction of the dimensionality of the problem by one.

  19. Geological record of fluid flow and seismogenesis along an erosive subducting plate boundary.

    Science.gov (United States)

    Vannucchi, Paola; Remitti, Francesca; Bettelli, Giuseppe

    2008-02-07

    Tectonic erosion of the overriding plate by the downgoing slab is believed to occur at half the Earth's subduction zones. In situ investigation of the geological processes at active erosive margins is extremely difficult owing to the deep marine environment and the net loss of forearc crust to deeper levels in the subduction zone. Until now, a fossil erosive subduction channel-the shear zone marking the plate boundary-has not been recognized in the field, so that seismic observations have provided the only information on plate boundary processes at erosive margins. Here we show that a fossil erosive margin is preserved in the Northern Apennines of Italy. It formed during the Tertiary transition from oceanic subduction to continental collision, and was preserved by the late deactivation and fossilization of the plate boundary. The outcropping erosive subduction channel is approximately 500 m thick. It is representative of the first 5 km of depth, with its deeper portions reaching approximately 150 degrees C. The fossil zone records several surprises. Two décollements were simultaneously active at the top and base of the subduction channel. Both deeper basal erosion and near-surface frontal erosion occurred. At shallow depths extension was a key deformation component within this erosive convergent plate boundary, and slip occurred without an observable fluid pressure cycle. At depths greater than about 3 km a fluid cycle is clearly shown by the development of veins and the alternation of fast (co-seismic) and slow (inter-seismic) slip. In the deepest portions of the outcropping subduction channel, extension is finally overprinted by compressional structures. In modern subduction zones the onset of seismic activity is believed to occur at approximately 150 degrees C, but in the fossil channel the onset occurred at cooler palaeo-temperatures.

  20. Surface constraints on the temporal and spatial evolution of the Farallon-Pacific-North America plate boundary

    Science.gov (United States)

    McQuarrie, N.; Oskin, M.

    2009-05-01

    Extension and volcanism are two surface derived data sets used to infer mantle processes back in time. We integrate two new large GIS-based datasets to create palinspastic restorations of extension and volcanism allowing us to readdress the relationship between plate-boundary deformation, intra-plate extension and magmatism in western North America. Using ArcGIS and custom software, we retrodeformed the NAVDat (North American Volcanic Database, navdat.geongrid.org) using the western North America reconstruction of McQuarrie and Wernicke (2005). We compare this data to strain rates calculated over a 50 km-grid forward- deformed from 36 Ma to present. With the deformed grid and palinspastically restored volcanic dataset we quantitatively compare rates of magmatism and deformation and evaluate the age, location, and migration of Cenozoic volcanic arcs. A first order conclusion from this study is that magmatism, throughout the Basin and Range, is primarily driven by plate boundary effects. The plate boundary effects include subduction and rollback of the Farallon plate, creation and expansion of slab windows as the Pacific plate intercepts the North American plate and re-establishment of the ancestral Cascade arc along the eastern margin of the Sierra Nevada at ˜ 15 Ma. Notable exceptions include the Yellowstone hotspot system along the northern boarder of our study area and late-stage (<8 Ma) passive, extension related asthenospheric upwelling that accompanied a thinning lithosphere along the eastern and western margins of the Basin and Range. The palinspastic reconstructions presented here highlight that the classic, high-angle, Basin and Range faulting that comprises most of the physiographic Basin and Range province commenced during a remarkably amagmatic period. These observations largely contradicts the active rifting model where magmatism triggers Basin and Range extension

  1. Spatially developing turbulent boundary layer on a flat plate

    CERN Document Server

    Lee, J H; Hutchins, N; Monty, J P

    2012-01-01

    This fluid dynamics video submitted to the Gallery of Fluid motion shows a turbulent boundary layer developing under a 5 metre-long flat plate towed through water. A stationary imaging system provides a unique view of the developing boundary layer as it would form over the hull of a ship or fuselage of an aircraft. The towed plate permits visualisation of the zero-pressure-gradient turbulent boundary layer as it develops from the trip to a high Reynolds number state ($Re_\\tau \\approx 3000$). An evolving large-scale coherent structure will appear almost stationary in this frame of reference. The visualisations provide an unique view of the evolution of fundamental processes in the boundary layer (such as interfacial bulging, entrainment, vortical motions, etc.). In the more traditional laboratory frame of reference, in which fluid passes over a stationary body, it is difficult to observe the full evolution and lifetime of turbulent coherent structures. An equivalent experiment in a wind/water-tunnel would requ...

  2. Discovering plate boundaries: Laboratory and classroom exercises using geodetic data to develop students' understanding of plate motion

    Science.gov (United States)

    Olds, S. E.

    2010-12-01

    To introduce the concept of plate boundaries, typical introductory geology exercises include students observing and plotting the location of earthquakes and volcanoes on a map to visually demarcate plate boundaries. Accompanying these exercises, students are often exposed to animations depicting the movement of Earth’s tectonic plates over time. Both of these teaching techniques are very useful for describing where the tectonics plates have been in the past, their shapes, and where the plates are now. With the integration of data from current geodetic techniques such as GPS, InSAR, LiDAR, students can learn that not only have the tectonic plates moved in the past, but they are moving, deforming, and changing shape right now. Additionally, GPS data can be visualized using time scales of days to weeks and on the scale of millimeters to centimeters per year. The familiar temporal and spatial scales of GPS data also help students understand that plate tectonics is a process that is happening in the present and can ease the transition to thinking about processes that are typically described using deep time, a very difficult concept for students to grasp. To provide a more robust learning environment, UNAVCO has been incorporating high-precision GPS data into free, place-based, data-rich learning modules for educators and students in introductory Earth science courses at secondary and undergraduate levels. These modules integrate new scientific discoveries related to crustal deformation and explore applications of GPS, LiDAR, and InSAR techniques to research. They also provide students with case studies highlighting the process of scientific discovery, providing context and meaning. Concurrent to these efforts, tools to visualize the inter-relationships of geophysical and geologic processes, structures, and measurements including high-precision GPS velocity data are an essential part of the learning materials. Among the suite of visualization tools that UNAVCO has made

  3. The Boundary States of the q-Deformed Supersymmetric t-J Model with a Boundary

    Institute of Scientific and Technical Information of China (English)

    YANG Wen-Li; ZHEN Yi

    2001-01-01

    The q-deformed supersymmetric t J model on a semi-infinite lattice is diagonalized by using the level-one vertex operators of the quantum affine superalgebra Uq[sl(2|1)]. We give the bosonization of the boundary states.``

  4. Buckling Analysis of Functionally Graded Material Plates Using Higher Order Shear Deformation Theory

    Directory of Open Access Journals (Sweden)

    B. Sidda Reddy

    2013-01-01

    Full Text Available The prime aim of the present study is to present analytical formulations and solutions for the buckling analysis of simply supported functionally graded plates (FGPs using higher order shear deformation theory (HSDT without enforcing zero transverse shear stresses on the top and bottom surfaces of the plate. It does not require shear correction factors and transverse shear stresses vary parabolically across the thickness. Material properties of the plate are assumed to vary in the thickness direction according to a power law distribution in terms of the volume fractions of the constituents. The equations of motion and boundary conditions are derived using the principle of virtual work. Solutions are obtained for FGPs in closed-form using Navier’s technique. Comparison studies are performed to verify the validity of the present results from which it can be concluded that the proposed theory is accurate and efficient in predicting the buckling behavior of functionally graded plates. The effect of side-to-thickness ratio, aspect ratio, modulus ratio, the volume fraction exponent, and the loading conditions on the critical buckling load of FGPs is also investigated and discussed.

  5. The Northern Caribbean Plate Boundary Offshore Hispaniola: Strike-slip and Compressive Tectonic Processes

    Science.gov (United States)

    Corbeau, J.; Rolandone, F.; Leroy, S. D.; Mercier De Lepinay, B. F.; Meyer, B.; Ellouz, N.

    2014-12-01

    The boundary between the Caribbean plate and the North American plate is transpressive due to the oblique collision between these two plates. The transpressive movement is partitioned and accommodated in the Hispaniola region along two left-lateral strike-slip structures surrounding a fold-and-thrust belt. New multibeam bathymetry data and multichannel seismic reflection profiles have been recently collected during the Haiti-SIS and Haiti-SIS 2 cruises, along part of the northern Caribbean plate boundary between Cuba, Jamaica and Hispaniola. From the north to the south, three types of deformations are observed. In the Windward Passage, the analysis of the data set reveals that the movement on the Oriente fault between Cuba and Hispaniola is purely left-lateral strike-slip according to the GPS measurements. In the Gonave basin, west of Hispaniola, the deformation is compressive. A series of folds is identified and moves toward the southwest. The Enriquillo-Plantain-Garden Fault (EPGF) is localized in the Jamaica Passage, between Jamaica and Hispaniola. The analysis of the data set reveals that the left-lateral EPGF recently intersects inherited basins from the eastern Cayman Trough margin. The study of the actual EPGF active trace shows that this fault moves with a pure strike-slip component, at least in its western part: the presence of a little push-up structure and a set of three en echelon folds is highlighting in the western part of the Jamaica Passage. The shortening rate in the inherited basins crossed by the EPGF increases from west to east (5.8% to 8.5%), indicating that a thrusting component is also accommodated around the EPGF.

  6. Dynamic Stability of Viscoelastic Plates with Finite Deformation and Shear Effects

    Institute of Scientific and Technical Information of China (English)

    李晶晶; 程昌钧; 等

    2002-01-01

    Based on Reddy's theory of plates with higher-order shear deformations and the Boltzmann superposition principles,the governing equations were established for dynamic stability of viscoelastic plates with finite deformations taking account of shear effects,The Galerkin method was applied to simplify the set of equations.The numerical methods in nonlinear dynamics were used to solve the simplified system.It could e seen that there are plenty of dynamic properties for this kind of viscoelastic plates under transverse harmonic loads.The influences of the transverse shear deformations and material parameter on the dynamic behavior of nonlinear viscoelatic plates were investigated.

  7. Vibration suppression for laminated composite plates with arbitrary boundary conditions

    Science.gov (United States)

    Li, J.; Narita, Y.

    2013-11-01

    An analysis of vibration suppression for laminated composite plates subject to active constrained layer damping under various boundary conditions is presented. Piezoelectric-fiber-reinforced composites (PFRCs) are used as active actuators, and the effect of PFRC patches on vibration control is reported here. An analytical approach is expanded to analyze the vibration of laminated composites with arbitrary boundary conditions. By using Hamilton's principle and the Rayleigh-Ritz method, the equation of motion for the resulting electromechanical coupling system is derived. A velocity feedback control rule is employed to obtain an effective active damping in the vibration control. The orientation effect of piezoelectric fibers in the PFRC patches on the suppression of forced vibrations is also investigated.

  8. How diking affects the longer-term structure and evolution of divergent plate boundaries

    KAUST Repository

    Trippanera, Daniele

    2015-04-01

    Recurrent diking episodes along divergent plate boundaries, as at Dabbahu (2005, Afar) or at Bardarbunga (2014, Iceland) , highlight the possibility to have m-wide opening in a short time (days to weeks). This suggests a prominent role of magma enhancing transient plate separations. However, the role of diking on a longer term (> 102 years) and its influence on the structure and the evolution of a divergent plate boundary is still poorly investigated. Here we use field surveys along the oceanic Icelandic and continental Ethiopian plate boundaries, along five eruptive fissures and four rift segments. Field observations have also been integrated with analogue and numerical models of dike emplacement to better understand the effect of dike emplacement at depth and at the surface. Our results show that the dike-fed eruptive fissures are systematically associated with graben structures formed by inward dipping normal faults having throws up to 10 m and commonly propagating downward. Moreover, rift segments (i.e. mature rift zones), despite any asymmetry and repetition, are characterized by the same features as the eruptive fissures, the only difference lying in the larger size (higher fault throws, up to 40 m, and wider deformation zones). Analogue and numerical models of dike intrusion confirm that all the structural features observed along the rift segments may be dike-induced; these features include downward propagating normal faults bordering graben structures, contraction at the base of the hanging walls of the faults and upward propagating faults. Simple calculations based on the deeper structure of the eroded rift segments in eastern and western Iceland also suggest that all the fault slip in the active rift segments may result from diking. These results suggest that the overall deformation pattern of eruptive fissures and rift segments may be explained only by dike emplacement. In a magmatic rift, the regional tectonic stress may rarely be high enough to be

  9. Seismotectonics of the Lwandle-Nubia plate boundary between South Africa and the Southwest Indian Ridge

    Science.gov (United States)

    Hartnady, Chris; Okal, Emile; Calais, Eric; Stamps, Sarah; Saria, Elifuraha

    2013-04-01

    The Lwandle (LW) plate shares a boundary with the Nubia (NU) plate, extending from a diffuse triple junction with the Rovuma plate in Southern Mozambique to a triple junction with the Antarctic plate along a segment of the Southwest Indian Ridge (SWIR). The LW-NU boundary terminates in the ~750 km-long, complex transform of the Andrew Bain Fracture Zone (ABFZ), but its exact locus is still unclear. Recent works locate it along the eastern boundary of the submarine Mozambique Ridge, parallel to the pre-existing, oceanic transform-fault fabric. However, an early concept of the LW block ('ambiguous region' of Hartnady, 1990, Fig. 2) indicates a more westerly trajectory in the north that includes parts of South Africa, with a southerly extension across old oceanic crust of the submarine Natal Valley and Transkei Basin. This proposed boundary is marked by several, aligned epicentres of moderate to strong earthquakes (1941, 1942, 1956, 1969, 1972, 1975, 1981 and 1989). Our re-examination of seismographic records from the 1975 'intraplate' earthquake (-37.62°N, 30.98°E, mb5.0), in the oceanic crust of the distal Transkei Basin, shows a thrust-faulting focal mechanism along a nodal plane striking N272°E. The largest (ML4.2) of a series of three small earthquakes in the Natal Valley in 2009, close to a zone of recent seafloor deformation mapped in 1992, has similar first-motion patterns at Southern African seismograph stations. When the 1975 slip-vector result (N173°E) is combined with a normal-faulting slip vector (N078°E) from a 1986 onland earthquake (-30.53°N, 28.84°E, mb5.0) near the Lesotho-KZN border, and both are incorporated into the wider data-set previously used to solve for East African Rift kinematics, they produce a LW-NU rotation pole that is located south of Africa, near the Agulhas Plateau, and approximately 950 km from the Natal Valley deformation zone. The modeled low rate of right-lateral, LW-NU slip (~0.50-0.75 mm/yr) across this LW-NU boundary

  10. Active faulting south of the Himalayan Front: Establishing a new plate boundary

    Science.gov (United States)

    Yeats, Robert S.; Thakur, V. C.

    2008-06-01

    New tectonic uplifts south of the Salt Range Thrust and Himalayan Front Thrust (HFT) represent an outward step of the plate boundary from the principal tectonic displacement zone into the Indo-Gangetic Plain. In Pakistan, the Lilla Anticline deforms fine-grained overbank deposits of the Jhelum River floodplain 15 km south of the Salt Range. The anticline is overpressured in Eocambrian non-marine strata. In northwest India south of Dehra Dun, the Piedmont Fault (PF) lies 15 km south of the HFT. Coalescing fans derived from the Himalaya form a piedmont (Old Piedmont Zone) 15-20 km wide east of the Yamuna River. This zone is uplifted as much as 15-20 m near the PF, and bedding is tilted 5-7° northeast. Holocene thermoluminescence-optically-stimulated luminescence dates for sediments in the Old Piedmont Zone suggest that the uplift rate might be as high as several mm/a. The Old Piedmont Zone is traced northwest 200 km and southeast another 200 km to the Nepal border. These structures, analogous to protothrusts in subduction zones, indicate that the Himalayan plate boundary is not a single structure but a series of structures across strike, including reactivated parts of the Main Boundary Thrust north of the range front, the HFT sensu stricto, and stepout structures on the Indo-Gangetic Plain. Displacement rates on all these structures must be added to determine the local India-Himalaya convergence rate.

  11. Numerical modeling of nonlinear deformation and buckling of composite plate-shell structures under pulsed loading

    Science.gov (United States)

    Abrosimov, N. A.

    1999-11-01

    Nonlinear three-dimensional problems of dynamic deformation, buckling, and posteritical behavior of composite shell structures under pulsed loads are analyzed. The structure is assumed to be made of rigidly joined plates and shells of revolution along the lines coinciding with the coordinate directions of the joined elements. Individual structural elements can be made of both composite and conventional isotropic materials. The kinematic model of deformation of the structural elements is based on Timoshenko-type hypotheses. This approach is oriented to the calculation of nonstationary deformation processes in composite structures under small deformations but large displacements and rotation angles, and is implemented in the context of a simplified version of the geometrically nonlinear theory of shells. The physical relations in the composite structural elements are based on the theory of effective moduli for individual layers or for the package as a whole, whereas in the metallic elements this is done in the framework of the theory of plastic flow. The equations of motion of a composite shell structure are derived based on the principle of virtual displacements with some additional conditions allowing for the joint operation of structural elements. To solve the initial boundary-value problem formulated, an efficient numerical method is developed based on the finite-difference discretization of variational equations of motion in space variables and an explicit second-order time-integration scheme. The permissible time-integration step is determined using Neumann's spectral criterion. The above method is especially efficient in calculating thin-walled shells, as well as in the case of local loads acting on the structural element, when the discretization grid has to be condensed in the zones of rapidly changing solutions in space variables. The results of analyzing the nonstationary deformation processes and critical loads are presented for composite and isotropic

  12. Architectural Blueprint for Plate Boundary Observatories based on interoperable Data Management Platforms

    Science.gov (United States)

    Kerschke, D. I.; Häner, R.; Schurr, B.; Oncken, O.; Wächter, J.

    2014-12-01

    Interoperable data management platforms play an increasing role in the advancement of knowledge and technology in many scientific disciplines. Through high quality services they support the establishment of efficient and innovative research environments. Well-designed research environments can facilitate the sustainable utilization, exchange, and re-use of scientific data and functionality by using standardized community models. Together with innovative 3D/4D visualization, these concepts provide added value in improving scientific knowledge-gain, even across the boundaries of disciplines. A project benefiting from the added value is the Integrated Plate boundary Observatory in Chile (IPOC). IPOC is a European-South American network to study earthquakes and deformation at the Chilean continental margin and to monitor the plate boundary system for capturing an anticipated great earthquake in a seismic gap. In contrast to conventional observatories that monitor individual signals only, IPOC captures a large range of different processes through various observation methods (e.g., seismographs, GPS, magneto-telluric sensors, creep-meter, accelerometer, InSAR). For IPOC a conceptual design has been devised that comprises an architectural blueprint for a data management platform based on common and standardized data models, protocols, and encodings as well as on an exclusive use of Free and Open Source Software (FOSS) including visualization components. Following the principles of event-driven service-oriented architectures, the design enables novel processes by sharing and re-using functionality and information on the basis of innovative data mining and data fusion technologies. This platform can help to improve the understanding of the physical processes underlying plate deformations as well as the natural hazards induced by them. Through the use of standards, this blueprint can not only be facilitated for other plate observing systems (e.g., the European Plate

  13. Existence of a natural instability not predicted by theory and connected to a wall deformation in a laminar boundary layer

    Science.gov (United States)

    Gougat, P.; Martin, F.

    1981-01-01

    Natural instability related to negative wall deformation was studied. It was shown that natural instabilities which propagate in a laminar boundary layer of a flat plate are in agreement with stability theory. It is found that if a wall has a deformation, a second frequency does exist, which is not predicted and is twice the first frequency. This second instable frequency only appears if there is a negative velocity gradient. The phenomenon is located very closely to the wall and drops off rapidly when moved away from it.

  14. Controllability of a viscoelastic plate using one boundary control in displacement or bending

    OpenAIRE

    Pandolfi, L.

    2016-01-01

    In this paper we consider a viscoelastic plate (linear viscoelasticity of the Maxwell-Boltzmann type) and we compare its controllability properties with the (known) controllability of a purely elastic plate (the control acts on the boundary displacement or bending). By combining operator and moment methods, we prove that the viscoelastic plate inherits the controllability properties of the purely elastic plate.

  15. Simulating biofilm deformation and detachment with the immersed boundary method

    CERN Document Server

    Sudarsan, Rangarajan; Stockie, John M; Eberl, Hermann J

    2015-01-01

    We apply the immersed boundary (or IB) method to simulate deformation and detachment of a periodic array of wall-bounded biofilm colonies in response to a linear shear flow. The biofilm material is represented as a network of Hookean springs that are placed along the edges of a triangulation of the biofilm region. The interfacial shear stress, lift and drag forces acting on the biofilm colony are computed by using fluid stress jump method developed by Williams, Fauci and Gaver [Disc. Contin. Dyn. Sys. B 11(2):519-540, 2009], with a modified version of their exclusion filter. Our detachment criterion is based on the novel concept of an averaged equivalent continuum stress tensor defined at each IB point in the biofilm which is then used to determine a corresponding von Mises yield stress; wherever this yield stress exceeds a given critical threshold the connections to that node are severed, thereby signalling the onset of a detachment event. In order to capture the deformation and detachment behaviour of a bio...

  16. Kinematics of the western Caribbean: Collision of the Cocos Ridge and upper plate deformation

    Science.gov (United States)

    Kobayashi, Daisuke; LaFemina, Peter; Geirsson, Halldór; Chichaco, Eric; Abrego, Antonio A.; Mora, Hector; Camacho, Eduardo

    2014-05-01

    Subduction of the Cocos plate and collision of the Cocos Ridge have profound effects on the kinematics of the western Caribbean, including crustal shortening, segmentation of the overriding plate, and tectonic escape of the Central American fore arc (CAFA). Tectonic models of the Panama Region (PR) have ranged from a rigid block to a deforming plate boundary zone. Recent expansion of GPS networks in Panama, Costa Rica, and Colombia makes it possible to constrain the kinematics of the PR. We present an improved kinematic block model for the western Caribbean, using this improved GPS network to test a suite of tectonic models describing the kinematics of this region. The best fit model predicts an Euler vector for the counterclockwise rotation of the CAFA relative to the Caribbean plate at 89.10°W, 7.74°N, 1.193° Ma-1, which is expressed as northwest-directed relative block rates of 11.3 ± 1.0-16.5 ± 1.1 mm a-1 from northern Costa Rica to Guatemala. This model also predicts high coupling along the Nicoya and Osa segments of the Middle American subduction zone. Our models demonstrate that the PR acts as a single tectonic block, the Panama block, with a predicted Euler vector of 107.65°W, 26.50°N, 0.133° Ma-1. This rotation manifests as northeast migration of the Panama block at rates of 6.9 ± 4.0-7.8 ± 4.8 mm a-1 from southern Costa Rica to eastern Panama. We interpret this motion as tectonic escape from Cocos Ridge collision, redirected by collision with the North Andes block, which migrates to the northwest at 12.2 ± 1.2 mm a-1.

  17. Deformation behaviour of body centered cubic iron nanopillars containing coherent twin boundaries

    OpenAIRE

    Sainath, G.; Choudhary, B. K.

    2016-01-01

    Molecular dynamics simulations were performed to understand the role of twin boundaries on deformation behaviour of body-centred cubic (BCC) iron (Fe) nanopillars. The twin boundaries varying from one to five providing twin boundary spacing in the range 8.5 - 2.8 nm were introduced perpendicular to the loading direction. The simulation results indicated that the twin boundaries in BCC Fe play a contrasting role during deformation under tensile and compressive loadings. During tensile deformat...

  18. An efficient strongly coupled immersed boundary method for deforming bodies

    Science.gov (United States)

    Goza, Andres; Colonius, Tim

    2016-11-01

    Immersed boundary methods treat the fluid and immersed solid with separate domains. As a result, a nonlinear interface constraint must be satisfied when these methods are applied to flow-structure interaction problems. This typically results in a large nonlinear system of equations that is difficult to solve efficiently. Often, this system is solved with a block Gauss-Seidel procedure, which is easy to implement but can require many iterations to converge for small solid-to-fluid mass ratios. Alternatively, a Newton-Raphson procedure can be used to solve the nonlinear system. This typically leads to convergence in a small number of iterations for arbitrary mass ratios, but involves the use of large Jacobian matrices. We present an immersed boundary formulation that, like the Newton-Raphson approach, uses a linearization of the system to perform iterations. It therefore inherits the same favorable convergence behavior. However, we avoid large Jacobian matrices by using a block LU factorization of the linearized system. We derive our method for general deforming surfaces and perform verification on 2D test problems of flow past beams. These test problems involve large amplitude flapping and a wide range of mass ratios. This work was partially supported by the Jet Propulsion Laboratory and Air Force Office of Scientific Research.

  19. Constraining deformation at the lithosphere-asthenosphere boundary beneath the San Andreas fault with Sp phases

    Science.gov (United States)

    Fischer, K. M.; Ford, H. A.; Lekic, V.

    2013-12-01

    The geometry of deformation in the deep mantle lithosphere beneath strike-slip plate boundaries has been enigmatic, with models ranging from localized shear zones that are deep extensions of individual crustal faults to broad zones of diffuse, distributed shear with widths of hundreds of kilometers. Using seismic phases that convert from shear to compressional motion (Sp) at the base of the lithosphere beneath California, we find evidence for strike-slip deformation in the deepest mantle lithosphere beneath the central San Andreas fault that occurs over a horizontal width of 50 km or less. This study is based on over 135,000 Sp receiver functions from 730 seismic stations, including the Northern and Southern California Seismic Networks and the NSF EarthScope Transportable and Flexible Arrays. Individual Sp receiver functions were calculated using an extended-time multi-taper method and were migrated and stacked according to their three-dimensional conversion point locations using a model for crust (Lowry and Pérez-Gussinyé, 2011) and mantle (Obrebski et al., 2010 and 2011) velocity structure beneath each station and a spline-function representation of the Sp Fresnel zone. Sp conversion points at lithosphere-asthenosphere boundary depths are very dense on both sides of the San Andreas fault, and we interpreted the Sp common conversion point stack only at those nodes with information from more than 300 receiver functions. To the east of the plate boundary, a strong coherent Sp phase, indicative of a decrease in shear-wave velocity with depth, is present in the depth range where tomographic studies image the transition from high velocity lithosphere to low velocity asthenosphere. This phase, interpreted as the seismological lithosphere-asthenosphere boundary, has systematically lower amplitudes on the western side of the plate boundary, indicating that the drop in shear velocity from lithosphere to asthenosphere is either smaller or is distributed over a larger

  20. Deformation and fracture of a plate under thermal shock

    Energy Technology Data Exchange (ETDEWEB)

    Aptukov, V.N.; Pozdeev, A.A.

    1986-01-01

    The wave processes associated with thermal shock give rise to cumulative tensile stresses whose magnitude and location are determined by the plate geometry, the heating region, and the spatial distribution of the heat sources. Here, the wave processes, damage accumulation, and the development of macrofracture zones during thermal shock are analyzed using a two-dimensional axisymmetric formulation. The evolution of macrocracks during thermal shock in a plate, a cylinder, and a partially heated plate is shown graphically. 14 references.

  1. Simulating Biofilm Deformation and Detachment with the Immersed Boundary Method

    Science.gov (United States)

    Sudarsan, Rangarajan; Ghosh, Sudeshna; Stockie, John M.; Eberl, Hermann J.

    2016-03-01

    We apply the immersed boundary (or IB) method to simulate deformation and detachment of a periodic array of wall-bounded biofilm colonies in response to a linear shear flow. The biofilm material is represented as a network of Hookean springs that are placed along the edges of a triangulation of the biofilm region. The interfacial shear stress, lift and drag forces acting on the biofilm colony are computed by using fluid stress jump method developed by Williams, Fauci and Gaver [Disc. Contin. Dyn. Sys. B 11(2):519-540, 2009], with a modified version of their exclusion filter. Our detachment criterion is based on the novel concept of an averaged equivalent continuum stress tensor defined at each IB point in the biofilm which is then used to determine a corresponding von Mises yield stress; wherever this yield stress exceeds a given critical threshold the connections to that node are severed, thereby signalling the onset of a detachment event. In order to capture the deformation and detachment behaviour of a biofilm colony at different stages of growth, we consider a family of four biofilm shapes with varying aspect ratio. Our numerical simulations focus on the behaviour of weak biofilms (with relatively low yield stress threshold) and investigate features of the fluid-structure interaction such as locations of maximum shear and increased drag. The most important conclusion of this work is that the commonly employed detachment strategy in biofilm models based only on interfacial shear stress can lead to incorrect or inaccurate results when applied to the study of shear induced detachment of weak biofilms. Our detachment strategy based on equivalent continuum stresses provides a unified and consistent IB framework that handles both sloughing and erosion modes of biofilm detachment, and is consistent with strategies employed in many other continuum based biofilm models.

  2. Boundary integral equation methods and numerical solutions thin plates on an elastic foundation

    CERN Document Server

    Constanda, Christian; Hamill, William

    2016-01-01

    This book presents and explains a general, efficient, and elegant method for solving the Dirichlet, Neumann, and Robin boundary value problems for the extensional deformation of a thin plate on an elastic foundation. The solutions of these problems are obtained both analytically—by means of direct and indirect boundary integral equation methods (BIEMs)—and numerically, through the application of a boundary element technique. The text discusses the methodology for constructing a BIEM, deriving all the attending mathematical properties with full rigor. The model investigated in the book can serve as a template for the study of any linear elliptic two-dimensional problem with constant coefficients. The representation of the solution in terms of single-layer and double-layer potentials is pivotal in the development of a BIEM, which, in turn, forms the basis for the second part of the book, where approximate solutions are computed with a high degree of accuracy. The book is intended for graduate students and r...

  3. Initial-boundary value problems for a class of nonlinear thermoelastic plate equations

    Institute of Scientific and Technical Information of China (English)

    Zhang Jian-Wen; Rong Xiao-Liang; Wu Run-Heng

    2009-01-01

    This paper studies initial-boundary value problems for a class of nonlinear thermoelastic plate equations. Under some certain initial data and boundary conditions,it obtains an existence and uniqueness theorem of global weak solutions of the nonlinear thermoelstic plate equations,by means of the Galerkin method. Moreover,it also proves the existence of strong and classical solutions.

  4. Accommodation of collisional shortening along the Alpine plate boundary : plate kinematics vs rheological controls

    Science.gov (United States)

    Rosenberg, Claudio; Bellahsen, Nicolas

    2016-04-01

    The style of collision in the Alps varies along strike, reflecting different amounts and different modes of accommodation of collisional shortening. These differences control the patterns of exhumation during collision. Whereas the western Alps largely consist of a metamorphic complex formed during subduction and largely exhumed before the initiation of collision, the subduction nappe-stack of the Central and the Eastern Alps is strongly overprinted by collisional shortening and by Barrovian metamorphism. Based on compiled and new data we estimate amounts of collisional shortening along the strike of the chain and set it in relationship to the geometry of the collisional prism. The western Alpine collisional structures form a very large (in map view), but moderately shortened wedge, terminating in front of a poorly developed Molasse basin. Shortening of this wedge was mainly localized along its external parts, resulting in accretion of basement and cover units thrusted towards the foreland. Back-folding and back-thrusting are barely developed and no shortening takes place in the upper, Adriatic plate. In the Central Alps, the amount of collisional shortening is larger and it is distributed both in the lower and in the upper plate. The collisional prism is bivergent and partitioning of the amount of shortening between the upper and lower plates varies along strike, being most probably controlled by rheological, heterogeneities. The thickened accreted lower plate is strongly affected by Barrovian metamorphism where shortening is largest and localized within a confined area. A deep Molasse basin developed in front of the prism. In the Eastern Alps collisional kinematics vary from east to west, with orogen-parallel displacements dominating in the east and orogen-perpendicular ones in the West, where they culminate in the structural and metamorphic dome of the Tauern Window. Nowhere else in the Alps collisional shortening is so strongly localized in one and the same

  5. Microstructural analysis and calcite piezometry on hydrothermal veins: Insights into the deformation history of the Cocos Plate at Site U1414 (IODP Expedition 344)

    Science.gov (United States)

    Brandstätter, Jennifer; Kurz, Walter; Rogowitz, Anna

    2017-08-01

    In this study we present microstructural data from hydrothermal veins in the sedimentary cover and the igneous basement recovered from Hole U1414A, Integrated Ocean Drilling Program (IODP) Expedition 344 (Costa Rica Seismogenesis Project), to constrain deformation mechanism operating in the subducting Cocos Plate. Cathodoluminescence studies, mechanical e-twin piezometry and electron backscatter diffraction (EBSD) analyses of carbonate veins were used to give insights into the deformation conditions and to help to understand the tectonic deformation history of the Cocos Plate offshore Costa Rica. Analyses of microstructures in the sedimentary rocks and in the basalt of the igneous basement reveal brittle deformation, as well as crystal-plastic deformation of the host rock and the vein material. Cathodoluminescence images showed that in the basalt fluid flow and related precipitation occurred over several episodes. The differential stresses, obtained from two different piezometers using the same parameter (twin density), indicate various mean differential stresses of 49 ± 11 and 69 ± 30 MPa and EBSD mapping of calcite veins reveals low-angle subgrain boundaries. Deformation temperatures are restricted to the range from 170°C to 220°C, due to the characteristics of the existing twins and the lack of high-temperature intracrystalline deformation mechanisms (>220°C). The obtained results suggest that deformation occurred over a period associated with changes of ambient temperatures, occurrence of fluids and hydrofracturing, induced differential stresses due to the bending of the plate at the trench, and related seismic activity.

  6. Evidence for fast seismic lid structure beneath the Californian margin and its implication on regional plate deformation

    Science.gov (United States)

    Lai, V. H.; Graves, R. W.; Wei, S.; Helmberger, D. V.

    2015-12-01

    The lithospheric structure of the Pacific and North American plates play an important role in modulating plate deformation along the California margin. Pure path models indicate that the Pacific plate has a fast thick (80km) lid overlaying a strong low velocity zone (LVZ) extending to beyond 300 km depth. In contrast, the North America structure is characterized by a relatively thin (25-35km) lid and a shallow LVZ. Vertical ray paths have similar travel times across the plate boundary for the two models, making resolution of the transitional structure difficult. Earthquakes such as the 2014 March 10 Mw 6.8 Mendocino and 2014 August 25 Mw 6.0 Napa events recorded at regional distances across California provide an opportunity to study horizontal paths and track the lateral variation in the lower crust-uppermost mantle structure under the Californian margin. Observations from both Napa and Mendocino events show direct SH-wave arrivals at Southern California Seismic Network (SCSN) stations are systematically earlier (up to 10 s) for coastal and island stations relative to inland sites. The shift in SH arrival times may be due to features such as varying crustal thickness, varying upper mantle velocity and the presence of a fast seismic lid. To test the different hypotheses, we perform extensive forward modeling using both 1-D frequency-wavenumber and 3-D finite-difference approaches. The model that best fits the SH arrival times has a fast lid (Vs = 4.7 km/s) underlying the whole California margin, with the lid increasing in thickness from east to west to a maximum thickness about 70 km in the western offshore region. The fast, thick seismic lid lends strength and rigidity to the Pacific plate lithosphere in contrast with the weaker North American continental plate, which influences the overall plate deformation along the Californian margin and is in agreement with GPS measurements.

  7. Crustal structure of the Eurasia-Africa plate boundary across the Gloria Fault, North Atlantic Ocean

    Science.gov (United States)

    Batista, Luis; Hübscher, Christian; Terrinha, Pedro; Matias, Luis; Afilhado, Alexandra; Lüdmann, Thomas

    2017-05-01

    The oceanic crustal and uppermost lithospheric mantle structure across the Gloria Fault (GF) transcurrent plate boundary between Africa and Eurasia in the Northeast Atlantic is investigated based on seismic reflection, seismic refraction and wide-angle reflection data. This experiment used 18 ocean bottom stations along an N-S 150 km long traverse together with acquisition of a multichannel seismic reflection profile. Modeling of P and S seismic waves and gravimetric anomalies allowed estimation of P- and S-wave velocities, density, Poisson's ratio and discussion of a compositional model. A five-layer model is proposed in which layers 1-3 correspond to normal sediments through typical oceanic crust layers 2 and 3. Layer 5 yielded mantle velocities above 7.9 km s-1. Layer 4 with 4 km of thickness has Vp velocities between 7.1 and 7.4 km s-1 and is clearly separated from typical oceanic crust and mantle layers. Comparison with natural analogues and published lab measurements suggest that layer 4 can be a mix of lithologies that comply with the estimated P and S velocities and computed Poisson's ratio and densities, such as, olivine cumulates, peridotite, gabbro and hydrated mantle. We favour the tectonic process that produces secondary porosity from which results serpentinization due to sea water circulation in fractures. Structural and seismic stratigraphic interpretation of the reflection profile shows that Neogene to recent tectonic deformation on this segment of the plate boundary concentrated on the southern side of the GF, that is, the Africa plate.

  8. Finite strip analysis of anisotropic laminated composite plates using higher-order shear deformation theory

    Science.gov (United States)

    Akhras, G.; Cheung, M. S.; Li, W.

    1994-08-01

    In the present study, a finite strip method for the elastic analysis of anisotropic laminated composite plates is developed according to higher-order shear deformation theory. This theory accounts for the parabolic distribution of the transverse shear strains through the thickness of the plate and for zero transverse shear stresses on the plate surfaces. In comparison with the finite strip method based on first-order shear deformation theory, the present method gives improved results while using approximately the same number of degrees of freedom. It also eliminates the need for shear correction factors in calculating the transverse shear stiffness.

  9. Deformation of rectangular thin glass plate coated with magnetostrictive material

    Science.gov (United States)

    Wang, Xiaoli; Yao, Youwei; Liu, Tianchen; Liu, Chian; Ulmer, M. P.; Cao, Jian

    2016-08-01

    As magnetic smart materials (MSMs), magnetostrictive materials have great potential to be selected as coating materials for lightweight x-ray telescope mirrors due to their capability to tune the mirror profile to the desired shape under a magnetic field. To realize this potential, it is necessary to study the deformation of the mirror substrate with the MSM coating subjected to a localized magnetic field. In this paper, an analytical model is developed to calculate the deformation of rectangular coated samples locally affected by magnetostrictive strains driven by an external magnetic field. As a specific case to validate the model, a square glass sample coated with MSMs is prepared, and its deformation is measured in a designed experimental setup by applying a magnetic field. The measured deformation of the sample is compared with the results calculated from the analytical model. The comparison results demonstrate that the analytical model is effective in calculating the deformation of a coated sample with the localized mismatch strains between the film and the substrate. In the experiments, different shape patterns of surface profile changes are achieved by varying the direction of the magnetic field. The analytical model and the experimental method proposed in this paper can be utilized to further guide the application of magnetostrictive coating to deformable lightweight x-ray mirrors in the future.

  10. Influence of Roll Elastic Deformation on Gaugemeter Equation for Plate Rolling

    Institute of Scientific and Technical Information of China (English)

    HU Xian-lei; WANG Jun; WANG Zhao-dong; LIU Xiang-hua; WANG Guo-dong

    2004-01-01

    The error of gaugemeter equation decreases the gap setting precision. The precision of gaugemeter equation is strongly influenced by plate width, work roll radius, backup roll radius, work roll crown, backup roll crown and rolling force. And these influences are hard to measure. All these factors are converted to roll deflection deformation and roll flattening deformation for calculation. In order to calculate the deformation, the theory of influence function method was adopted. By using simulation program, the influence of these factors on deformation was obtained. Then a simple model can be built. With this model, it is convenient to analyze the influence of different factors on gaugemeter equation.

  11. The role of near-trench extension at convergent plate boundaries

    Science.gov (United States)

    Vannucchi, P.

    2009-04-01

    Knowledge of how convergent plate boundary coupling in the seismogenic zone controls the nucleation of subduction zone earthquakes is fundamental to assess seismic risks. Increased data at convergent margins has revealed the complexity of the earthquake cycle through the detection of strain-release processes like episodic tremors and slip events, low frequency earthquakes, afterslip, slip heterogeneity along the fault plane. The processes controlling the earthquake cycle and their interactions are still far from being understood; improved understanding will require better characterization of the fault zone. Here we compare in-situ observations from two major subduction zones drilled by ODP and IODP (Costa Rica Trench and Nankai Trough) with a well-preserved fossil convergent plate boundary zone in the Northern Apennines of Italy. At all three sites, deformation in the region above and at the updip limit of the seismogenic zone is dominated by extension and normal faulting (i.e. maximum principal stress is oriented sub-vertically). Episodes of reverse shearing are also present, but occur with less intensity, alternating with extension. Ocean Drilling Program Legs 170 and 205 offshore Costa Rica provide structural observations of the frontal part of the upper plate and décollement at about 2 km from the trench. Analysis of drilled cores reveals the presence of normal faults cutting the frontal part of the upper plate. Normal faults are also seen from seismic reflection to develop along all the forearc (about 60 km from the trench). The décollement damage zone is a few tens of meters in width; it develops mainly within frontal prism material. A clear cm-thick fault core is observed 1.6 km from the trench. Both the upper plate and the décollement damage zone show the co-existence of two distinct fracturing processes in which extension fracturing is frequent in the upper part of the damage zone farthest from the fault core, while both extension and shear fracturing

  12. Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation.

    Directory of Open Access Journals (Sweden)

    J Farley Norman

    Full Text Available It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped "glaven" for 12 seconds and were required to indicate which of 12 (for bell peppers or 8 (for glavens simultaneously visible objects possessed the same shape. The initial single object's shape was defined either by boundary contours alone (i.e., presented as a silhouette, specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions-e.g., the participants' performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions. The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision.

  13. Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation

    Science.gov (United States)

    Cheeseman, Jacob R.; Thomason, Kelsey E.; Ronning, Cecilia; Behari, Kriti; Kleinman, Kayla; Calloway, Autum B.; Lamirande, Davora

    2016-01-01

    It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped “glaven”) for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object’s shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions–e.g., the participants’ performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision. PMID:26863531

  14. Deformation and Metasomatic Evolution at the Subduction Plate Interface As Viewed from Study of HP/UHP Metamorphic Rocks

    Science.gov (United States)

    Bebout, G. E.; Penniston-Dorland, S.

    2014-12-01

    We provide a view of lithologic makeup, deformation, and fluid-rock interaction along the deep forearc to subarc plate interface, based on insights gained from study of HP/UHP metamorphic rocks. Exposures of plate-boundary shear zones on which we base our perspective represent 30-80 km depths and are on Catalina Island and at Monviso, Syros, and New Caledonia. Each contains highly deformed zones with schistose matrix, commonly with a large ultramafic component, containing bodies of less deformed mafic, sedimentary, and ultramafic rocks. These "blocks" have varying geometries, are up to km-scale, and can preserve disparate P-T histories reflecting dynamics of incorporation and entrainment. Sheared matrices contain high-variance, hydrous mineral assemblages in some cases resembling metasomatic zones ("rinds") at block-matrix contacts, and rinds and matrices have homogenized isotopic compositions reflecting extensive fluid-rock interaction. Shearing and related physical juxtaposition of disparate metasomatic rocks can result in mixed or 'hybrid' chemical compositions. The chlorite-, talc-, and amphibole-rich schists developed by these processes can stabilize H2O to great depth and influence its cycling. Fluids (hydrous fluids, silicate melts) released within slabs necessarily interact with highly deformed, lithologically hybridized zones at the plate interface as they ascend to potentially enter mantle wedges. Fluids bearing chemical/isotopic signatures of hybrid rocks appear capable of producing arc magma compositions interpreted as reflecting multiple, chemically distinct fluids sources. Geophysical signatures of these rheologically weak zones are equivocal but many recognize the presence of zones of low seismic velocity at/near the top of slabs and attribute them to hydrated rocks. Whether rocks from this interface buoyantly ascend into mantle wedges, indicated in some theoretical models, remains largely untested by field and geophysical observations.

  15. On plane stress state and stress free deformation of thick plate with FGM interface under thermal loading

    Science.gov (United States)

    Szubartowski, Damian; Ganczarski, Artur

    2016-10-01

    This paper demonstrates the plane stress state and the stress free thermo-elastic deformation of FGM thick plate under thermal loading. First, the Sneddon-Lockett theorem on the plane stress state in an isotropic infinite thick plate is generalized for a case of FGM problem in which all thermo-mechanical properties are optional functions of depth co-ordinate. The proof is based on application of the Iljushin thermo-elastic potential to displacement type system of equations that reduces it to the plane stress state problem. Then an existence of the purely thermal deformation is proved in two ways: first, it is shown that the unique solution fulfils conditions of simultaneous constant temperature and linear gradation of thermal expansion coefficient, second, proof is based directly on stress type system of equations which straightforwardly reduces to compatibility equations for purely thermal deformation if only stress field is homogeneous in domain and at boundary. Finally, couple examples of application to an engineering problem are presented.

  16. Transcurrent reactivation of Australia's western passive margin: An example of intraplate deformation from the central Indo-Australian plate

    Science.gov (United States)

    Hengesh, J. V.; Whitney, B. B.

    2016-05-01

    Australia's northwestern passive margin intersects the eastern termination of the Java trench segment of the Sunda arc subduction zone and the western termination of Timor trough along the Banda arc tectonic collision zone. Differential relative motion between the Sunda arc subduction zone and the Banda arc collision zone has reactivated the former rifted margin of northwestern Australia evidenced by Pliocene to Quaternary age deformation along a 1400 km long offshore fault system. The fault system has higher rates of seismicity than the adjacent nonextended crustal terranes, has produced the largest historical earthquake in Australia (1941 ML 7.3 Meeberrie event), and is dominated by focal mechanism solutions consistent with dextral motion along northeast trending fault planes. The faults crosscut late Miocene unconformities that are eroded across middle Miocene inversion structures suggesting multiple phases of Neogene and younger fault reactivation. Onset of deformation is consistent with the timing of the collision of the Scott Plateau part of the passive continental margin with the former Banda trench between 3.0 Ma and present. The range of estimated maximum horizontal slip rates across the zone is ~1.4 to 2.6 mm yr-1, at the threshold of geodetically detectable motion, yet significant with respect to an intraplate tectonic setting. The folding and faulting along this part of the continental margin provides an example of intraplate deformation resulting from kinematic transitions along a distant plate boundary and demonstrates the presence of a youthful evolving intraplate fault system within the Indo-Australian plate.

  17. Logistical Support for the Installation of the Plate Boundary Observatory GPS and Borehole Strainmeter Networks

    Science.gov (United States)

    Kurnik, C.; Austin, K.; Coyle, B.; Dittmann, T.; Feaux, K.; Friesen, B.; Johnson, W.; Mencin, D.; Pauk, B.; Walls, C.

    2007-12-01

    The Plate Boundary Observatory (PBO), part of the NSF-funded EarthScope project, is designed to study the three- dimensional strain field resulting from deformation across the active boundary zone between the Pacific and North American plates in the western United States. To meet these goals, UNAVCO will install 880 continuous GPS stations, 103 borehole strainmeter stations, 28 tiltmeters, and five laser strainmeters by October 2008. Such a broad network presents significant logisitical challenges, including moving supplies, equipment, and personnel around 6 million square kilometers, and this requires accurate tracking and careful planning. The PBO logistics chain includes the PBO headquarters at UNAVCO in Boulder, Colorado and five regional offices in the continental United States and Alaska, served by dozens of suppliers spread across the globe. These offices are responsible for building and maintaining sites in their region. Most equipment and supplies first arrive in Boulder, where they are tagged and entered into a UNAVCO-wide equipment database, assembled and quality checked as necessary, and sent on to the appropriate regional office. Larger items which are costly to store and ship from Boulder, such as batteries or long sections of stainless steel pipe and bar required for monuments, are shipped directly from the supplier to each region as needed. These supplies and equipment are also tracked through the ordering, delivery, installation, and maintenance cycle via Earned Value Management techniques which allow us to meet NSF and other Federal procurement rules. Early prototypes and assembly configurations aid the development of material and supply budgets. A thorough understanding of Federal procurement rules at project start up is critical as the project moves forward.

  18. Observing tectonic plate motions and deformations from satellite laser ranging

    Science.gov (United States)

    Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

    1985-01-01

    The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

  19. Observing tectonic plate motions and deformations from satellite laser ranging

    Science.gov (United States)

    Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

    1985-01-01

    The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

  20. Deformation induced dislocation boundaries: Alignment and effect on mechanical properties

    DEFF Research Database (Denmark)

    Winther, G.; Juul Jensen, D.

    1997-01-01

    The dislocation boundaries formed during cold-rolling of FCC metals have been reported to have a preferred macroscopic direction with respect to the sample axes. However, boundaries have also been reported to form on crystallographic slip planes. The directions of the boundaries formed on crystal...

  1. MHD Boundary Layer Slip Flow and Heat Transfer over a Flat Plate

    Institute of Scientific and Technical Information of China (English)

    Krishnendu Bhattacharyya; Swati Mukhopadhyay; G.C.Layek

    2011-01-01

    An analysis of magnetohydrodynamic (MHD) boundary layer flow and heat transfer over a flat plate with slip condition at the boundary is presented. A complete self-similar set of equations are obtained from the governing equations using similarity transformations and are solved by a shooting method. In the boundary slip condition no local similarity occurs. Velocity and temperature distributions within the boundary layer are presented. Our analysis reveals that the increase of magnetic and slip parameters reduce the boundary layer thickness and also enhance the heat transfer from the plate.%@@ An analysis of magnetohydrodynamic (MHD) boundary layer flow and heat transfer over a flat plate with slip condition at the boundary is presented.A complete self-similar set of equations are obtained from the governing equations using similarity transformations and are solved by a shooting method.In the boundary slip condition no local similarity occurs.Velocity and temperature distributions within the boundary layer are presented.Our analysis reveals that the increase of magnetic and slip parameters reduce the boundary layer thickness and also enhance the heat transfer from the plate.

  2. Nonlocal Elasticity Theory for Transient Analysis of Higher-Order Shear Deformable Nanoscale Plates

    Directory of Open Access Journals (Sweden)

    Woo-Young Jung

    2014-01-01

    Full Text Available The small scale effect on the transient analysis of nanoscale plates is studied. The elastic theory of the nano-scale plate is reformulated using Eringen’s nonlocal differential constitutive relations and higher-order shear deformation theory (HSDT. The equations of motion of the nonlocal theories are derived for the nano-scale plates. The Eringen’s nonlocal elasticity of Eringen has ability to capture the small scale effects and the higher-order shear deformation theory has ability to capture the quadratic variation of shear strain and consequently shear stress through the plate thickness. The solutions of transient dynamic analysis of nano-scale plate are presented using these theories to illustrate the effect of nonlocal theory on dynamic response of the nano-scale plates. On the basis of those numerical results, the relations between nonlocal and local theory are investigated and discussed, as are the nonlocal parameter, aspect ratio, side-to-thickness ratio, nano-scale plate size, and time step effects on the dynamic response. In order to validate the present solutions, the reference solutions are employed and examined. The results of nano-scale plates using the nonlocal theory can be used as a benchmark test for the transient analysis.

  3. Hydrological Effects in the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Meertens, C.; Wahr, J.; Borsa, A.; Jackson, M.; Wahr, A.

    2008-12-01

    The dense network of 1,100 continuously operating GPS stations in the Plate Boundary Observatory (PBO) is providing high quality position time series. Data are processed by PBO Analysis Centers at the New Mexico Institute of Mining and Technology and at Central Washington University. The results are combined by the Analysis Center Coordinator at the Massachusetts Institute of Technology and are made available from the UNAVCO Data Center in Boulder. Analysis software of Langbein, 2008, was used to estimate secular trends and annual variations in the time series. The results were interpreted in terms of hydrological loading and poroelastic effects, from both natural and anthropogenic changes in water storage. The effects of monument stability were also considered. The density of PBO observations allows for the identification of spatial patterns that appear coherent over relatively broad areas. Vertical annual signals of 8-10 mm peak-to-peak amplitude are evident at stations in the mountains of northern and central California and southern Oregon showing peak uplift in October and are correlated to hydrological loading. The vertical elastic loading signal, calculated from the 0.25 by 0.25 degree community Noah land-surface model, fits the annual signal well and appears also to model the secular trends, although the time duration of ~3 years is still limited. In contrast to mountainous regions, stations in the valleys of California show greater spatial variability ranging from stations with almost no detectable annual signal to stations with very large, 20-30 mm, amplitudes with peak uplift in March. The vertical signals are temporally correlated to ground-water variations caused by pumping for agricultural irrigation and likely are caused by poroelastic effects in the sediments rather than loading. Annual vertical signals in southern California, where not obviously influenced from localized ground-water fluctuations, are small with ~2 mm amplitude and may be due to

  4. Upper plate deformation as marker for the Northern STEP fault of the Ionian slab (Tyrrhenian Sea, central Mediterranean)

    Science.gov (United States)

    Milia, Alfonsa; Iannace, Pietro; Tesauro, Magdala; Torrente, Maurizio M.

    2017-07-01

    The Eastern Tyrrhenian margin (ETM), the active boundary of the Tyrrhenian Sea backarc basin, is the key for understanding the geodynamics of the central Mediterranean. Numerous seismic tomography studies have been carried out in this region, proposing different reconstructions of the lower subducting plate and cause of the slab-break-off existing beneath the Southern Apennines. However, the area and mode of the recent deformation of the Tyrrhenian Sea are still not fully defined and understood. In this study, we combine the analysis of a recent seismic tomography model and geological data, in order to understand the relationship between the subducting lower plate and the tectonic evolution of the sedimentary basins formed on the upper plate. With this aim, we interpreted a large data set of seismic reflection profiles and several well logs. The results consist in 2D and 3D geological models of the basins, sedimentary infill, and fault networks. Taking into account the geological data of the ETM and those of the adjacent inner flank of the Apennines, we observe: (i) a system of linked sedimentary basins developed on a narrow deformation belt bounded by transform fault zones; (ii) a polyphase rifting within the upper plate; (iii) an abrupt change of the direction of extension ( 90°), from NE-oriented in the Lower Pleistocene to SE-oriented in the Middle Pleistocene. Since these ETM features are not the typical expressions of the current backarc extensional models, we propose a link between the evolution of upper plate and the onset and development of a STEP (Subduction-Transform-Edge-Propagator) fault along the northern margin of the Ionian slab.

  5. Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

    Science.gov (United States)

    Hamers, M. F.; Pennock, G. M.; Drury, M. R.

    2016-11-01

    The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

  6. An accurate higher order displacement model with shear and normal deformations effects for functionally graded plates

    Energy Technology Data Exchange (ETDEWEB)

    Jha, D.K., E-mail: dkjha@barc.gov.in [Civil Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Kant, Tarun [Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India); Srinivas, K. [Civil Engineering Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Singh, R.K. [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2013-12-15

    Highlights: • We model through-thickness variation of material properties in functionally graded (FG) plates. • Effect of material grading index on deformations, stresses and natural frequency of FG plates is studied. • Effect of higher order terms in displacement models is studied for plate statics. • The benchmark solutions for the static analysis and free vibration of thick FG plates are presented. -- Abstract: Functionally graded materials (FGMs) are the potential candidates under consideration for designing the first wall of fusion reactors with a view to make best use of potential properties of available materials under severe thermo-mechanical loading conditions. A higher order shear and normal deformations plate theory is employed for stress and free vibration analyses of functionally graded (FG) elastic, rectangular, and simply (diaphragm) supported plates. Although FGMs are highly heterogeneous in nature, they are generally idealized as continua with mechanical properties changing smoothly with respect to spatial coordinates. The material properties of FG plates are assumed here to vary through thickness of plate in a continuous manner. Young's modulii and material densities are considered to be varying continuously in thickness direction according to volume fraction of constituents which are mathematically modeled here as exponential and power law functions. The effects of variation of material properties in terms of material gradation index on deformations, stresses and natural frequency of FG plates are investigated. The accuracy of present numerical solutions has been established with respect to exact three-dimensional (3D) elasticity solutions and the other models’ solutions available in literature.

  7. Plate boundaries and evolution of the Solomon Sea region

    Science.gov (United States)

    Honza, E.; Davies, H. L.; Keene, J. B.; Tiffin, D. L.

    1987-09-01

    The Solomon Sea Plate was widely developed during late Oligocene, separating the proto-West Melanesian Arc from the proto-Trobriand Arc. Spreading in the Bismarck Sea and in the Woodlark Basin resulted from interaction between the Pacific and Australian Plates, specifically from the collision of the proto-West Melanesian Arc with north New Guinea, which occurred after arc reversal. This model explains the extensive Miocene, Pliocene, and Quaternary volcanism of the Papua New Guinea mainland as it related to southward subduction of the Trobriand Trough. Our interpreted plate motions are concordant with the geological evidence onshore and also with complex tectonic features in the Solomon Sea Basin Region.

  8. Active faulting and transpression tectonics along the plate boundary in North Africa

    OpenAIRE

    Mustapha Meghraoui; Silvia Pondrelli

    2012-01-01

    International audience; We present a synthesis of the active tectonics of the northern Atlas Mountains , and suggest a kinematic model of transpression and block rotation that illustrates the mechanics of this section of the Africa–Eurasia plate boundary. Neotectonic structures and significant shallow seismicity (with Mw >5.0) indicate that coeval E-W-trending, right-lateral faulting and NE-SW, thrust-related folding result from oblique convergence at the plate boundary, which forms a transpr...

  9. The Quest for the Africa-Eurasia plate boundary West of the Strait of Gibraltar

    Science.gov (United States)

    Zitellini, N.

    2009-04-01

    A new swath bathymetry compilation of the Gulf of Cadiz Area and SW Iberia is presented. The new map is the result of a collaborative research performed after year 2000 by teams from 7 European countries and 14 research institutions. This new dataset allow for the first time to present and to discuss the missing link in the plate boundary between Eurasia and Africa in the Central Atlantic. A set of almost linear and sub parallel dextral strike-slip faults, the SWIM Faults (SWIM is the acronym of the ESF EuroMargins project "Earthquake and Tsunami hazards of active faults at the South West Iberian Margin: deep structure, high-resolution imaging and paleoseismic signature") was mapped using a the new swath bathymetry compilation available in the area. The SWIM Faults form a narrow band of deformation over a length of 600 km coincident with a small circle centred on the pole of rotation of Africa with respect to Eurasia, This narrow band of deformation connects the Gloria Fault to the Rif-Tell Fault Zone, two segments of the plate boundary between Africa and Eurasia. In addition, the SWIM faults cuts across the Gulf of Cadiz, in the Atlantic Ocean, where the 1755 Great Lisbon earthquake, M~8.5-8.7, and tsunami were generated, providing a new insights on its source location. SWIM Team: E. Gràcia (2), L. Matias (3), P. Terrinha (4), M.A. Abreu (5), G. DeAlteriis(6), J.P. Henriet (7), J.J. Dañobeitia (2), D.G. Masson (8), T. Mulder (9), R. Ramella (10), L. Somoza (11) and S. Diez (2) (2) Unitat de Tecnologia Marina (CSIC), Centre Mediterrani d'Investigacions Marines i Ambientals, Barcelona, Spain (3) Centro Geofísica da Universidade de Lisboa (CGUL, IDL), Lisboa, Portugal (4) National Institute for Engineering, Technology and Innovation (INETI, LATTEX), Departamento de Geologia Marinha, Amadora, Portugal (5) Estrutura de Missão para a Extensão da Plataforma Continental, Lisboa, Portugal (6) Geomare Sud IAMC, CNR, Napoli, Italy (7) Renard Centre of Marine Geology

  10. Thermal stresses and deformations in a plate subject to the action of concentrated energy flows

    Energy Technology Data Exchange (ETDEWEB)

    Rudin, G.I.

    1988-09-01

    A two-dimensional problem concerned with the determination of thermal deformation and the temperature and stress fields in a plate subject to nonhomogeneous heating by a radiative flow of Gaussian type is solved. Cases in which one plate surface is either free or clamped onto a rigid base as well as cases in which the energy source is a laser beam are also considered. Factors such as the thermal diffusivity, specific heat, plate density, linear expansion, shear modulus, optical and energy absorption behavior, and refractivity are incorporated into the solution.

  11. A simple higher order shear deformation theory for mechanical behavior of laminated composite plates

    Science.gov (United States)

    Adim, Belkacem; Daouadji, Tahar Hassaine; Rabahi, Aberezak

    2016-06-01

    In the present study, the static, buckling, and free vibration of laminated composite plates is examined using a refined shear deformation theory and developed for a bending analysis of orthotropic laminated composite plates. These models take into account the parabolic distribution of transverse shear stresses and satisfy the condition of zero shear stresses on the top and bottom surfaces of the plates. The most interesting feature of this theory is that it allows for parabolic distributions of transverse shear stresses across the plate thickness and satisfies the conditions of zero shear stresses at the top and bottom surfaces of the plate without using shear correction factors. The number of independent unknowns in the present theory is four, as against five in other shear deformation theories. In the analysis, the equation of motion for simply supported thick laminated rectangular plates is obtained through the use of Hamilton's principle. The accuracy of the analysis presented is demonstrated by comparing the results with solutions derived from other higher order models and with data found in the literature. It can be concluded that the proposed theory is accurate and simple in solving the static, the buckling, and free vibration behaviors of laminated composite plates.

  12. The transition from linear to diffuse plate boundary in the Azores-Gibraltar region: results from a thin-sheet model

    Science.gov (United States)

    Jiménez-Munt, Ivone; Fernàndez, Manel; Torne, Montse; Bird, Peter

    2001-10-01

    We use the thin-sheet plane-stress approach to study the present-day dynamic behavior of the plate boundary between Eurasia and Africa along the Azores-Gibraltar region. This plate boundary, which extends from the Azores triple junction to the Gibraltar strait, shows a tectonic regime that changes from transtension in the west to transpression in the east, with a strike-slip motion in its central segment. Seismological data reveal that the western and central segments are currently marked by a linear series of earthquakes indicating that the plate boundary is located in a narrow zone. In contrast, the eastern segment is not so well defined and deformation spreads over a much broader area. To apply the thin-sheet approach, we combined heat flow, elevation and crustal thickness data to calculate the steady-state geotherm and the total strength of the lithosphere. Several models with different fault friction coefficients and geometries at the eastern segment of the plate boundary were tested. Results are compared with the maximum compressive stress directions from the World Stress Map, and the calculated seismic strain rates and slip vectors from earthquake data. The best fitting models are consistent with the rotation pole of Argus et al. [D.F. Argus et al., J. Geophys. Res. 94 (1989) 5585-5602], and show that the rheological behavior of the plate boundary must necessarily change from the western and central segments to the eastern segment. The diffuse character of the plate boundary east of the Gorringe Bank is dominated by the transition from oceanic to continental lithosphere, the weakness of the Alboran domain, and the convergence between the African and the Eurasian plates. The displacement of the Alboran domain relative to the African plate may play a major role in stress propagation through the Iberian Peninsula and its Atlantic margin.

  13. Structural coarsening during annealing of an aluminum plate heavily deformed using ECAE

    DEFF Research Database (Denmark)

    Mishin, Oleg V.; Zhang, Yubin; Godfrey, A.

    2015-01-01

    The microstructure and softening behaviour have been investigated in an aluminum plate heavily deformed by equal channel angular extrusion and subsequently annealed at 170 °C. It is found that at this temperature the microstructure evolves by coarsening with no apparent signs of recrystallization...

  14. Thermal deformation in a thin circular plate due to a partially distributed heat supply

    Indian Academy of Sciences (India)

    N L Khobragade; K C Deshmukh

    2005-08-01

    In this paper, we develop an integral transform to determine temperature distribution in a thin circular plate, subjected to a partially distributed and axisymmetric heat supply on the curved surface, and study the thermal deformation. The results, obtained in series form in terms of Bessel’s functions, are illustrated numerically.

  15. Recrystallization at grain boundaries in deformed copper bicrystals

    NARCIS (Netherlands)

    Heller, H.W.F.; Verbraak, C.A.; Kolster, B.H.

    1984-01-01

    The role of specific grain boundaries in the nucleation of recrystallization textures is demonstrated by experiments on copper bicrystals. It is deduced that the major part of the recrystallized grains that have nucleated at the grain boundary can be traced back to having nucleated in {100} <001>, {

  16. Effect of different heating methods on deformation of metal plate under upsetting mechanism in laser forming

    Science.gov (United States)

    Shi, Yongjun; Liu, Yancong; Yi, Peng; Hu, Jun

    2012-03-01

    In a laser forming process, different forming mechanisms have different deformation behaviors. The aim of laser forming is to acquire plane strain under an upsetting mechanism, while a plate undergoes a small bending deformation. In some industrial applications, the bending strain should not occur. To achieve high-precision forming, the deformation behaviors of a metal plate when an upsetting mechanism plays a dominant role are studied in the paper. Several heating methods are proposed to reduce the plane strain difference along the thickness direction and little bending deformation resulting from a small temperature difference between the top and bottom surfaces of the plate. The results show that negligible bending deformation and a uniform plastic plane strain field can be obtained by simultaneously heating the top and bottom surfaces with the same process parameters. A conventional scanning method needs a larger spot diameter and slower scanning speed under the upsetting mechanism, but a smaller spot diameter and quicker scanning speed may be selected using the simultaneous heating method, which can greatly widen the potential scope of process parameters.

  17. A global attractor for a fluid--plate interaction model accounting only for longitudinal deformations of the plate

    CERN Document Server

    Chueshov, Igor

    2010-01-01

    We study asymptotic dynamics of a coupled system consisting of linearized 3D Navier--Stokes equations in a bounded domain and the classical (nonlinear) elastic plate equation for in-plane motions on a flexible flat part of the boundary. The main peculiarity of the model is the assumption that the transversal displacements of the plate are negligible relative to in-plane displacements. This kind of models arises in the study of blood flows in large arteries. Our main result states the existence of a compact global attractor of finite dimension. We also show that the corresponding linearized system generates exponentially stable $C_0$-semigroup. We do not assume any kind of mechanical damping in the plate component. Thus our results means that dissipation of the energy in the fluid due to viscosity is sufficient to stabilize the system.

  18. Core-mantle boundary deformations and J2 variations resulting from the 2004 Sumatra earthquake

    CERN Document Server

    Cannelli, V; De Michelis, P; Piersanti, A; Florindo, F

    2007-01-01

    The deformation at the core-mantle boundary produced by the 2004 Sumatra earthquake is investigated by means of a semi-analytic theoretical model of global coseismic and postseismic deformation, predicting a millimetric coseismic perturbation over a large portion of the core-mantle boundary. Spectral features of such deformations are analysed and discussed. The time-dependent postseismic evolution of the elliptical part of the gravity field (J2) is also computed for different asthenosphere viscosity models. Our results show that, for asthenospheric viscosities smaller than 10^18 Pa s, the postseismic J2 variation in the next years is expected to leave a detectable signal in geodetic observations.

  19. Characterization of Grain Boundaries in Superplastically Deformed Y-TZP Ceramics

    NARCIS (Netherlands)

    Boutz, Michel M.R.; Chen, Chu Sheng; Winnubst, Louis; Burggraaf, Anthonie J.

    1994-01-01

    The effects of compressive deformation on the grain boundary characteristics of fine-grained Y-TZP have been investigated using surface spectroscopy, impedance analysis, and transmission electron microscopy. After sintering at low temperature (1150°C), the grain boundaries are covered by an ultrathi

  20. Effect of plastic deformation on diffusion-rolling bonding of steel sandwich plates

    Institute of Scientific and Technical Information of China (English)

    Hong Li; Jingtao Han

    2006-01-01

    Diffusion bonding is one of the most important techniques for composite materials, while bonding temperature, holding time,and rolling reduction are the key parameters that affect the bonding strength of sandwich plates. To study the effect of plastic deformation on the bonding strength, laboratory experiments were carried on a Gleeble Thermal Simulator to imitate the diffusion-rolling bonding under different reductions for steel sandwich plates. The bonding strength and interlayer film thickness were measured, and the element diffusion was analyzed using line scanning. The relationship between the bonding strength and "diffused interlayer" thickness was investigated. It has been found that the bonding strength increases with reduction, whereas the interlayer film thickness decreases gradually as the reduction increases. The diffusion under plastic deformation is obviously enhanced in comparison with that of nil reduction. The mechanism of plastic deformation effect on the diffusion bonding and related models have been discussed.

  1. Local equivalent welding element to predict the welding deformations of plate-type structures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Considering the Heat Affected Zone (HAZ) of welding joint, the residual strain be-haviors of material under constraint and temperature circulation, as well as the activating mechanism of welding process, this paper addresses a new type welding element for numerical simulation of welding deformation, which is called the LEWE (the local equivalent welding element). This element can describe the basic char-acteristics of welded seam: the local position points of inherent strain, the equiva-lent size, the bending radius (or bending angle) from inherent strain, etc. It could be used to predict the welding deformation of plate-type structure. The comparisons between the computed deflection of welded plate and its experiment measurement are present. The results showed that the LEWE possesses a potential to simulate the deformation of welding process high-efficiently and precisely.

  2. DUAL RECIPROCITY BOUNDARY ELEMENT METHOD FOR FLEXURAL WAVES IN THIN PLATE WITH CUTOUT

    Institute of Scientific and Technical Information of China (English)

    GAO Suo-wen; WANG Yue-sheng; ZHANG Zi-mao; MA Xing-rui

    2005-01-01

    The theoretical analysis and numerical calculation of scattering of elastic waves and dynamic stress concentrations in the thin plate with the cutout was studied using dual reciprocity boundary element method (DRM). Based on the work equivalent law, the dual reciprocity boundary integral equations for flexural waves in the thin plate were established using static fundamental solution. As illustration, numerical results for the dynamic stress concentration factors in the thin plate with a circular hole are given.The results obtained demonstrate good agreement with other reported results and show high accuracy.

  3. Effects of microscopic boundary conditions on plastic deformations of small-sized single crystals

    DEFF Research Database (Denmark)

    Kuroda, Mitsutoshi; Tvergaard, Viggo

    2009-01-01

    The finite deformation version of the higher-order gradient crystal plasticity model proposed by the authors is applied to solve plane strain boundary value problems, in order to obtain an understanding of the effect of the higher-order boundary conditions. Numerical solutions are carried out...... effect of higher-order boundary conditions on the overall deformation mode of the block is observed. The bent foil has free surfaces through which dislocations can go out of the material, and we observe a strong size-dependent mechanical response resulting from the surface condition assumed....

  4. Coideal Quantum Affine Algebra and Boundary Scattering of the Deformed Hubbard Chain

    CERN Document Server

    de Leeuw, Marius; Regelskis, Vidas

    2011-01-01

    We consider boundary scattering for a semi-infinite one-dimensional deformed Hubbard chain with boundary conditions of the same type as for the Y=0 giant graviton in the AdS/CFT correspondence. We show that the recently constructed quantum affine algebra of the deformed Hubbard chain has a coideal subalgebra which is consistent with the reflection (boundary Yang-Baxter) equation. We derive the corresponding reflection matrix and furthermore show that the aforementioned algebra in the rational limit specializes to the (generalized) twisted Yangian of the Y = 0 giant graviton.

  5. Stress and mixed boundary conditions for two-dimensional dodecagonal quasi-crystal plates

    Indian Academy of Sciences (India)

    Yan Gao; Si-Peng Xu; Bao-Sheng Zhao

    2007-05-01

    For plate bending and stretching problems in two-dimensional (2D) dodecagonal quasi-crystal (QC) media, the reciprocal theorem and the general solution for QCs are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all order. The method developed by Gregory and Wan is used to generate necessary conditions which the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the plate; these decaying state conditions are obtained explicitly for axisymmetric bending and stretching of a circular plate when stress or mixed conditions are imposed on the plate edge. They are then used for the correct formulation of boundary conditions for the interior solution. For the stress data, our boundary conditions coincide with those obtained in conventional forms of plate theories. More importantly, appropriate boundary conditions with a set of mixed edge-data are obtained for the first time. Furthermore, the corresponding necessary conditions for transversely isotropic elastic plate are obtained directly, and their isotropic elastic counterparts are also obtained.

  6. Dynamics of evolving phase boundaries in deformable continua

    Directory of Open Access Journals (Sweden)

    Morton E. Gurtin

    1991-05-01

    Full Text Available Recent studies of Gurtin [8,9,10], Angenent and Gurtin [4], and Gurtin and Struthers [15] form an investigation whose goal is a nonequilibrium thermodynamics of two-phase continua in which the interface is sharp and endowed with energy, entropy and superficial force. In all of these studies except the last the crystal is rigid, an assumption that forms the basis for a large class of problems discussed by material scientists, but there are situations in which deformation is the paramount concern, examples being shock-ind of Gurtin and Struthers, who consider deformable crystal-crystal systems with coherent interfaced transformations and mechanical twinning. Here I discuss the results of Gurtin and Struthers, who consider deformable crystal-crystal systems with coherent interface.

  7. Upper boundary of the Pacific plate subducting beneath Hokkaido, Japan, estimated from ScSp phase

    OpenAIRE

    Osada, Kinue; Yoshizawa, Kazunori; YOMOGIDA, Kiyoshi

    2010-01-01

    Three-dimensional geometry of the upper boundary of the Pacific plate subducting beneath Hokkaido, Japan, was obtained using the ScSp phase: the phase converted from ScS (S wave reflected at the core-mantle boundary) to P wave at the plate boundary. Taking the advantage of a dense seismic network, "Hi-net", recently deployed across the Japanese islands, we applied several seismic array analyses to the recorded waveform data for a large nearby deep earthquake, in order to enhance very weak ScS...

  8. Geometrically nonlinear vibration analysis of piezoelectrically actuated FGM plate with an initial large deformation

    Energy Technology Data Exchange (ETDEWEB)

    Naei, Mohammad Hassan; Rastgoo, Abbas [University of Tehran, Tehran (Iran, Islamic Republic of); Ebrahimi, Farzad [Faculty of Engineering and Technology, lmam Khomeini International University, Qazvin (Iran, Islamic Republic of)

    2009-08-15

    A theoretical model for geometrically nonlinear vibration analysis of piezoelectrically actuated circular plates made of functionally grade material (FGM) is presented based on Kirchhoff's-Love hypothesis with von-Karman type geometrical large nonlinear deformations. To determine the initial stress state and pre-vibration deformations of the smart plate a nonlinear static problem is solved followed by adding an incremental dynamic state to the pre-vibration state. The derived governing equations of the structure are solved by exact series expansion method combined with perturbation approach. The material properties of the FGM core plate are assumed to be graded in the thickness direction according to the power-law distribution in terms of the volume fractions of the constituents. Control of the FGM plate's nonlinear deflections and natural frequencies using high control voltages is studied and their nonlinear effects are evaluated. Numerical results for FG plates with various mixture of ceramic and metal are presented in dimensionless forms. In a parametric study the emphasis is placed on investigating the effect of varying the applied actuator voltage as well as gradient index of FGM plate on vibration characteristics of the smart structure

  9. New method for solving the bending problem of rectangular plates with mixed boundary conditions

    Directory of Open Access Journals (Sweden)

    Liu Xin Min

    2016-01-01

    Full Text Available A new method is used to solve the rectangular plate bending problem with mixed boundary conditions. The method overcomes the complicated derivation of the classical solution by Fourth-order differential problem into integrating question. Under uniform loading rectangular plate bending problem with one side fixed the opposite side half simply supported half fixed the other two sides free rectangular plate, one side simply supported the opposite side half simply supported half fixed the other two sides free rectangular plate is systematically solved. According to the actual boundary conditions of the rectangular plate, the corresponding characteristic equation can easily be set up. It is presented deflection curve equation and the numerical calculation. By compared the results of the equation to the finite element program, we are able to demonstrate the correctness of the method. So the method not only has certain theoretical value, but also can be directly applied to engineering practice.

  10. The Cause of the Republic Day Earthquake of India: Intraplate or Plate Boundary Process?

    Science.gov (United States)

    Li, Q.

    2001-12-01

    The Mw 7.6 Republic Day (1/26/2001) earthquake of India killed at least 14,000 people and destroyed tens of thousands of homes. The cause of this earthquake and other historic earthquakes in the surrounding region, all thrust faults with roughly N-S compression, has been the subject of intensive debate. Some workers argued that this earthquake, located ~400 km from the plate boundary, is an intraplate event that may bear important implications for other intraplate earthquakes such as those in the New Madrid seismic zone. Others, however, recognize the diffuse plate boundary in western India and regard this earthquake as part of the plate boundary activity. We have developed a viscoelastic finite element model to address the question of why this and other historic earthquakes concentrated in this part of the India plate. The computer model includes relevant boundary conditions and first-order rheologic variations as indicated by geological and seismic data. We calculated the stresses within the India plate using displacement boundary conditions as indicated by the GPS data and compared the predicted stresses with the theoretical crustal strengths. Our results indicate that the change of plate boundary conditions (from transform fault along the Owen Fracture zone in the India ocean to continental thrusting and shearing along northwestern India) causes stress to accumulate in a broad zone near the junction of the Indian, the Arabian, and the Eurasian plates. Crustal weakening by diffuse seismicity along the northwestern Indian plate boundary may cause further inland migration of stress accumulation. With additional factors, including the contrasts of the crustal strength between the continental and oceanic Indian plate, the presence of the Kachchh rift zone, and the pronounced thinning of the lithosphere in this region as indicated by seismic tomography, the model predict an earthquake-prone belt extending hundreds of kilometers into the interior of the India plate

  11. Reorganization of convergent plate boundaries. Geologica Ultraiectina (340)

    NARCIS (Netherlands)

    Baes, M.|info:eu-repo/dai/nl/304824739

    2011-01-01

    It is still unclear where a subduction is initiated and what are the responsible mechanisms involved in subduction initiation process. Understanding of subduction initiation will advance our knowledge of how and when plate tectonics started on Earth. Another issue concerning the subduction process

  12. Deformation of the Manazuru Knoll in Sagami Bay, central Japan, associated with subduction of the Philippine Sea plate

    Science.gov (United States)

    No, Tetsuo; Takahashi, Narumi; Miura, Seiichi; Yamashita, Mikiya; Kido, Yukari; Kodaira, Shuichi

    2014-12-01

    In January 2010, we conducted a multichannel seismic (MCS) reflection survey in Sagami Bay. As a result of this study, the deformation of the Manazuru Knoll, which is located near the plate boundary, was obtained. The Manazuru Knoll was formed by an asymmetric anticline, and the knoll has a geometry that is bent in a shape similar to that of a crank. The anticlinal axis, which was confirmed by MCS data, lies along the anticlinal axis shown on the bathymetric map, and the axis is bent first to the southeast and then to the east. It is estimated that the easternmost part of Manazuru Knoll has reached the vicinity of Miura Canyon. The offset of the strike of the anticline axis is approximately 7 km. A reverse fault related to the formation of Manazuru Knoll was identified in the southwestern side of the knoll. It is hypothesized that this reverse fault formed as a result of shortening of the structure, which occurred when the relative motion of the Philippine Sea plate was acting in a perpendicular direction close to the Manazuru Knoll. Therefore, it is estimated that the relative motion of the Philippine Sea plate was almost oblique or parallel to the anticlinal axis of Manazuru Knoll and that the eastern end of Manazuru Knoll was bent into a crank shape by strike-slip motion. This suggests that a part of Manazuru Knoll, located to the west of the plate boundary, moved to the northwest. Finally, it is assumed that the sediments of Miura Canyon and Sagami Knoll have been overlapping on the eastern end of Manazuru Knoll.

  13. Finite Element Analysis of the Deformation of Functionally Graded Plates under Thermomechanical Loads

    Directory of Open Access Journals (Sweden)

    A. E. Alshorbagy

    2013-01-01

    Full Text Available The first-order shear deformation plate model, accounting for the exact neutral plane position, is exploited to investigate the uncoupled thermomechanical behavior of functionally graded (FG plates. Functionally graded materials are mainly constructed to operate in high temperature environments. Also, FG plates are used in many applications (such as mechanical, electrical, and magnetic, where an amount of heat may be generated into the FG plate whenever other forms of energy (electrical, magnetic, etc. are converted into thermal energy. Several simulations are performed to study the behavior of FG plates, subjected to thermomechanical loadings, and focus the attention on the effect of the heat source intensity. Most of the previous studies have considered the midplane neutral one, while the actual position of neutral plane for functionally graded plates is shifted and should be firstly determined. A comparative study is performed to illustrate the effect of considering the neutral plane position. The volume fraction of the two constituent materials of the FG plate is varied smoothly and continuously, as a continuous power function of the material position, along the thickness of the plate.

  14. Linking mantle dynamics, plate tectonics and surface processes in the active plate boundary zones of eastern New Guinea (Invited)

    Science.gov (United States)

    Baldwin, S.; Moucha, R.; Fitzgerald, P. G.; Hoke, G. D.; Bermudez, M. A.; Webb, L. E.; Braun, J.; Rowley, D. B.; Insel, N.; Abers, G. A.; Wallace, L. M.; Vervoort, J. D.

    2013-12-01

    Eastern New Guinea lies within the rapidly obliquely converging Australian (AUS)- Pacific (PAC) plate boundary zone and is characterized by transient plate boundaries, rapidly rotating microplates and a globally significant geoid high. As the AUS plate moved northward in the Cenozoic, its leading edge has been a zone of subduction and arc accretion. The variety of tectonic settings in this region permits assessment of the complex interplay among mantle dynamics, plate tectonics, and surface processes. Importantly, the timescale of tectonic events (e.g., subduction, (U)HP exhumation, seafloor spreading) are within the valid bounds of mantle convection models. A record of changes in bathymetry and topography are preserved in high standing mountain belts, exhumed extensional gneiss domes and core complexes, uplifted coral terraces, and marine sedimentary basins. Global seismic tomography models indicate accumulation of subducted slabs beneath eastern New Guinea at the bottom of the upper mantle (i.e., 250-300 km). Preliminary global-scale backward advected mantle convection models, driven by density inferred from joint seismic-geodynamic tomography models, exhibit large-scale flow associated with these subducted slab remnants and predict the timing and magnitude (up to 1500 m) of dynamic topography change (both subsidence and uplift) since the Oligocene. In this talk we will explore the effects of large-scale background mantle flow and plate tectonics on the evolution of topography and bathymetry in eastern New Guinea, and discuss possible mechanisms to explain basin subsidence and surface uplift in the region.

  15. Seismicity and Seismic Hazard along the Western part of the Eurasia-Nubia plate boundary

    Science.gov (United States)

    Bezzeghoud, Mourad; Fontiela, João; Ferrão, Celia; Borges, José Fernando; Caldeira, Bento; Dib, Assia; Ousadou, Farida

    2016-04-01

    The seismic phenomenon is the most damaging natural hazard known in the Mediterranean area. The western part of the Eurasia-Nubia plate boundary extends from the Azores to the Mediterranean region. The oceanic part of the plate boundary is well delimited from the Azores Islands, along the Azores-Gibraltar fault to approximately 12°W (west of the Strait of Gibraltar). From 12°W to 3.5°E, including the Iberia-Nubia region and extending to the western part of Algeria, the boundary is more diffuse and forms a wider area of deformation. The boundary between the Iberia and Nubia plates is the most complex part of the margin. This region corresponds to the transition from an oceanic boundary to a continental boundary, where Iberia and Nubia collide. Although most earthquakes along this plate boundary are shallow and generally have magnitudes less than 5.5, there have been several high-magnitude events. Many devastating earthquakes, some of them tsunami-triggering, inflicted heavy loss and considerable economic damage to the region. From 1920 to present, three earthquakes with magnitudes of about 8.0 (Mw 8.2, 25 November 1941; Ms 8.0, 25 February 1969; and Mw 7.9, 26 May 1975) occurred in the oceanic region, and four earthquakes with magnitudes of about 7.0 (Mw 7.1, 8 May 1939, Santa Maria Island and Mw 7.1, January 1980, Terceira and Graciosa Islands, both in the Azores; Ms 7.1, 20 May 1931, Azores-Gibraltar fracture zone; and Mw 7.3, 10 October 1980, El Asnam, Algeria) occurred along the western part of the Eurasia-Nubia plate boundary. In general, large earthquakes (M ≥7) occur within the oceanic region, with the exception of the El Asnam (Algeria) earthquakes. Some of these events caused extensive damage. The 1755 Lisbon earthquake (˜Mw 9) on the Portugal Atlantic margin, about 200 km W-SW of Cape St. Vincent, was followed by a tsunami and fires that caused the near-total destruction of Lisbon and adjacent areas. Estimates of the death toll in Lisbon alone (~70

  16. Analytical Solutions to the Fundamental Frequency of Arbitrary Laminated Plates under Various Boundary Conditions

    Institute of Scientific and Technical Information of China (English)

    Yingqin Luo; Ming Hong; Yuan Liu

    2015-01-01

    In recent years, as the composite laminated plates are widely used in engineering practice such as aerospace, marine and building engineering, the vibration problem of the composite laminated plates is becoming more and more important. Frequency, especially the fundamental frequency, has been considered as an important factor in vibration problem. In this paper, a calculation method of the fundamental frequency of arbitrary laminated plates under various boundary conditions is proposed. The vibration differential equation of the laminated plates is established at the beginning of this paper and the frequency formulae of specialty orthotropic laminated plates under various boundary conditions and antisymmetric angle-ply laminated plates with simply-supported edges are investigated. They are proved to be correct. Simple algorithm of the fundamental frequency for multilayer antisymmetric and arbitrary laminated plates under various boundary conditions is studied by a series of typical examples. From the perspective of coupling, when the number of laminated plates layersN > 8–10, some coupling influence on the fundamental frequency can be neglected. It is reasonable to use specialty orthotropic laminated plates with the same thickness but less layers to calculate the corresponding fundamental frequency of laminated plates. Several examples are conducted to prove correctness of this conclusion. At the end of this paper, the influence of the selected number of layers of specialty orthotropic laminates on the fundamental frequency is investigated. The accuracy and complexity are determined by the number of layers. It is necessary to use proper number of layers of special orthotropic laminates with the same thickness to simulate the fundamental frequency in different boundary conditions.

  17. An Immersed Boundary Finite-Element Solver for Flow-Induced Deformation of Soft Structures with Application in Cardiac Flows

    Science.gov (United States)

    Bhardwaj, Rajneesh; Mittal, Rajat

    2011-11-01

    The modeling of complex biological phenomena such as cardiac mechanics is challenging. It involves complex three dimensional geometries, moving structure boundaries inside the fluid domain and large flow-induced deformations of the structure. We present a fluid-structure interaction solver (FSI) which couples a sharp-interface immersed boundary method for flow simulation with a powerful finite-element based structure dynamics solver. An implicit partitioned (or segregated) approach is implemented to ensure the stability of the solver. We validate the FSI solver with published benchmark for a configuration which involves a thin elastic plate attached to a rigid cylinder. The frequency and amplitude of the oscillations of the plate are in good agreement with published results and non-linear dynamics of the plate and its coupling with the flow field are discussed. The FSI solver is used to understand left-ventricular hemodynamics and flow-induced dynamics of mitral leaflets during early diastolic filling and results from this study are presented.

  18. Lost in Iceland? Fracture Zone Complications Along the Mid-Atlantic Plate Boundary

    Science.gov (United States)

    Brandsdóttir, B.; Einarsson, P.; Detrick, R. S.; Mayer, L.; Calder, B.; Driscoll, N.; Richter, B.

    2003-12-01

    The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. Two transform zones, the South Iceland Seismic Zone (SISZ) and the Tjörnes Fracture Zone (TFZ) separate the on land rift zones from the Reykjanes Ridge (RR), and the Kolbeinsey Ridge (KR), offshore N-Iceland. Both are markedly different from fracture zones elsewhere along the plate boundary. The 80 km E-W and 10--15 km N-S SISZ is made up of more than 20 N-S aligned, right-lateral, strike-slip faults whereas the TFZ consists of a broad zone of deformation, roughly 150 km E-W and 75 km N-S. The over-all left-lateral transform motion within the SISZ is accommodated by bookshelf faulting whereas the right-lateral transform motion within the TFZ is incorporated within two WNW-trending seismic zones, spaced ˜40 km apart, the Grímsey Seismic Zone (GSZ) and the Húsavík-Flatey fault (HFF). Recently collected EM300 and RESON8101 multibeam bathymetric data along with CHIRP subbottom data has unveiled some tectonic details within the TFZ. The GSZ runs along the offshore extension of the Northern Volcanic Rift Zone (NVRZ) and is made up of four left-stepping, en-echelon, NS-striking rift segments akin to those on land. Large GSZ earthquakes seem to be associated with lateral strike-slip faulting along ESE-striking fault planes. Fissure swarms transecting the offshore volcanic systems have also been subjected to right-lateral transformation along the spreading direction. As the Reykjanes Peninsula, the on land extension of the RR, the GSZ bears the characteristics of an oblique rift zone. The plate boundary segments connecting to the RR and KR are thus symmetrical with respect to the plate separation vector (105° ) and orientation of individual volcanic systems. The HFF has an overall strike of N65° W and can be traced continuously along its 75--80 km length, between the Theistareykir volcanic system within the NVRZ, across the central TFZ-graben, the Skjálfandi bay, and into the largest

  19. Prediction of Thermal and Elastic Properties of Honeycomb Sandwich Plate for Analysis of Thermal Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seok Min; Lee, Jang Il; Byun, Jae Ki; Choi, Young Don [Korea Univ., Seoul (Korea, Republic of)

    2014-04-15

    Thermal problems that are directly related to the lifetime of an electronic device are becoming increasingly important owing to the miniaturization of electronic devices. To solve thermal problems, it is essential to study thermal stability through thermal diffusion and insulation. A honeycomb sandwich plate has anisotropic thermal conductivity. To analyze the thermal deformation and temperature distribution of a system that employs a honeycomb sandwich plate, the thermal and elastic properties need to be determined. In this study, the thermal and elastic properties of a honeycomb sandwich plate, such as thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and shear modulus, are predicted. The properties of a honeycomb sandwich plate vary according to the hexagon size, thickness, and material properties.

  20. Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California

    Science.gov (United States)

    Ramsay, Joseph; Kohler, Monica D.; Davis, Paul M.; Wang, Xinguo; Holt, William; Weeraratne, Dayanthie S.

    2016-10-01

    SKS arrivals from ocean bottom seismometer (OBS) data from an offshore southern California deployment are analysed for shear wave splitting. The project involved 34 OBSs deployed for 12 months in a region extending up to 500 km west of the coastline into the oceanic Pacific plate. The measurement process consisted of removing the effects of anisotropy using a range of values for splitting fast directions and delay times to minimize energy along the transverse seismometer axis. Computed splitting parameters are unexpectedly similar to onland parameters, exhibiting WSW-ENE fast polarization directions and delays between 0.8 and 1.8 s, even for oceanic plate sites. This is the first SKS splitting study to extend across the entire boundary between the North America and Pacific plates, into the oceanic part of the Pacific plate. The splitting results show that the fast direction of anisotropy on the Pacific plate does not align with absolute plate motion (APM), and they extend the trend of anisotropy in southern California an additional 500 km west, well onto the oceanic Pacific plate. We model the finite strain and anisotropy within the asthenosphere associated with density-buoyancy driven mantle flow and the effects of APM. In the absence of plate motion effects, such buoyancy driven mantle flow would be NE-directed beneath the Pacific plate observations. The best-fit patterns of mantle flow are inferred from the tomography-based models that show primary influences from foundering higher-density zones associated with the history of subduction beneath North America. The new offshore SKS measurements, when combined with measurements onshore within the plate boundary zone, indicate that dramatic lateral variations in density-driven upper-mantle flow are required from offshore California into the plate boundary zone in California and western Basin and Range.

  1. Magnetic Fluid-Based Squeeze Film Behaviour in Curved Porous-Rotating Rough Annular Plates and Elastic Deformation Effect

    Directory of Open Access Journals (Sweden)

    M. E. Shimpi

    2012-01-01

    Full Text Available Efforts have been directed to study and analyze the squeeze film performance between rotating transversely rough curved porous annular plates in the presence of a magnetic fluid lubricant considering the effect of elastic deformation. A stochastic random variable with nonzero mean, variance, and skewness characterizes the random roughness of the bearing surfaces. With the aid of suitable boundary conditions, the associated stochastically averaged Reynolds' equation is solved to obtain the pressure distribution in turn, which results in the calculation of the load-carrying capacity. The graphical representations establish that the transverse roughness, in general, adversely affects the performance characteristics. However, the magnetization registers a relatively improved performance. It is found that the deformation causes reduced load-carrying capacity which gets further decreased by the porosity. This investigation tends to indicate that the adverse effect of porosity, standard deviation and deformation can be compensated to certain extent by the positive effect of the magnetic fluid lubricant in the case of negatively skewed roughness by choosing the rotational inertia and the aspect ratio, especially for suitable ratio of curvature parameters.

  2. Holocene faulting in the Bellingham forearc basin: upper-plate deformation at the northern end of the Cascadia subduction zone

    Science.gov (United States)

    Kelsey, Harvey M.; Sherrod, Brian L.; Blakely, Richard J.; Haugerud, Ralph A.

    2013-01-01

    The northern Cascadia forearc takes up most of the strain transmitted northward via the Oregon Coast block from the northward-migrating Sierra Nevada block. The north-south contractional strain in the forearc manifests in upper-plate faults active during the Holocene, the northern-most components of which are faults within the Bellingham Basin. The Bellingham Basin is the northern of four basins of the actively deforming northern Cascadia forearc. A set of Holocene faults, Drayton Harbor, Birch Bay, and Sandy Point faults, occur within the Bellingham Basin and can be traced from onshore to offshore using a combination of aeromagnetic lineaments, paleoseismic investigations and scarps identified using LiDAR imagery. With the recognition of such Holocene faults, the northernmost margin of the actively deforming Cascadia forearc extends 60 km north of the previously recognized limit of Holocene forearc deformation. Although to date no Holocene faults are recognized at the northern boundary of the Bellingham Basin, which is 15 km north of the international border, there is no compelling tectonic reason to expect that Holocene faults are limited to south of the international border.

  3. Long-range stresses associated with boundaries in deformed materials

    DEFF Research Database (Denmark)

    Leffers, T.

    1995-01-01

    around the boundaries, a population which, because of the long-range stresses associated, does not represent a perfect LEDS, but the deviation is moderate. For polycrystals with flat grains and for polycrystals with the grains subdivided into flat bands the geometrically necessary dislocations may remain...... in the (grain or band) boundaries, but they still represent a certain, moderate deviation from LEDS. A distinction is made between two contributions from the geometrically necessary dislocations to hardening: conservative hardening which is associated with long-range stresses and frictional hardening which...

  4. Parametric study on supersonic flutter of angle-ply laminated plates using shear deformable finite element method

    Institute of Scientific and Technical Information of China (English)

    Wei Xia; Qiao Ni

    2011-01-01

    The influence of fiber orientation,flow yaw angle and length-to-thickness ratio on flutter characteristics of angle-ply laminated plates in supersonic flow is studied by finite element approach.The structural model is established using the Reissner-Mindlin theory in which the transverse shear deformation is considered.The aerodynamic pressure is evaluated by the quasi-steady first-order piston theory.The equations of motion are formulated based on the principle of virtual work.With the harmonic motion assumption,the flutter boundary is determined by solving a series of complex eigenvalue problems.Numerical study shows that (1)The flutter dynamic pressure and the coalescence of flutter modes depend on fiber orientation,flow yaw angle and length-to-thickness ratio; (2) The laminated plate with all fibers aligned with the flow direction gives the highest flutter dynamic pressure,but a slight yawing of the flow from the fiber orientation results in a sharp decrease of the flutter dynamic pressure; (3) The angle-ply laminated plate with fiber orientation angle equal to flow yaw angle gives high flutter dynamic pressure,but not the maximum flutter dynamic pressure; (4) With the decrease of length-to-thickness ratio,an adverse effect due to mode transition on the flutter dynamic pressure is found.

  5. Numerical analysis of thermal deformation in laser beam heating of a steel plate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Kim, Yong-Rae; Kim, Jae-Woong [Yeungnam University, Kyongsan (Korea, Republic of)

    2017-05-15

    Line heating is a widely used process for plate forming or thermal straightening. Flame heating and induction heating are the traditional heating processes used by industry for line heating. However, these two heating processes are ineffective when used on small steel plates. Thus, the laser beam heating with various power profiles were carried out in this study. A comparison of numerical simulation results and experimental results found a significant difference in the thermal deformation when apply a different power profile of laser beam heating. The one-sinusoid power profile produced largest thermal deformation in this study. The laser beam heating process was simulated by established a combined heat source model, and simulated results were compared with experimental results to confirm the model’s accuracy. The mechanism of thermal deformation was investigated and the effects of model parameters were studied intensively with the finite element method. Thermal deformation was found to have a significant relationship with the amount of central zone plastic deformation. Scientists and engineers could use this study’s verified model to select appropriate parameters in laser beam heating process. Moreover, by using the developed laser beam model, the analysis of welding residual stress or hardness could also be investigated from a power profile point of view.

  6. Rupture across arc segment and plate boundaries in the 1 April 2007 Solomons earthquake

    Science.gov (United States)

    Taylor, Frederick W.; Briggs, Richard W.; Frohlich, Cliff; Brown, Abel; Hornbach, Matt; Papabatu, Alison K.; Meltzner, Aron J.; Billy, Douglas

    2008-04-01

    The largest earthquakes are generated in subduction zones, and the earthquake rupture typically extends for hundreds of kilometres along a single subducting plate. These ruptures often begin or end at structural boundaries on the overriding plate that are associated with the subduction of prominent bathymetric features of the downgoing plate. Here, we determine uplift and subsidence along shorelines for the 1 April 2007 moment magnitude MW 8.1 earthquake in the western Solomon Islands, using coral microatolls which provide precise measurements of vertical motions in locations where instrumental data are unavailable. We demonstrate that the 2007 earthquake ruptured across the subducting Simbo ridge transform and thus broke through a triple junction where the Australian and Woodlark plates subduct beneath the overriding Pacific plate. Previously, no known major megathrust rupture has involved two subducting plates. We conclude that this event illustrates the uncertainties of predicting the segmentation of subduction zone rupture on the basis of structural discontinuities.

  7. Deformation of nanocrystalline binary aluminum alloys with segregation of Mg, Co and Ti at grain boundaries

    Science.gov (United States)

    Zinovev, A. V.; Bapanina, M. G.; Babicheva, R. I.; Enikeev, N. A.; Dmitriev, S. V.; Zhou, K.

    2017-01-01

    The influence of the temperature and sort of alloying element on the deformation of the nanocrystalline (NC) binary Al alloys with segregation of 10.2 at % Ti, Co, or Mg over grain boundaries has been studied using the molecular dynamics. The deformation behavior of the materials has been studied in detail by the simulation of the shear deformation of various Al bicrystals with the grain-boundary segregation of impurity atoms, namely, Ti, Co, or Mg. The deformation of bicrystals with different grain orientation has been studied. It has been found that Co introduction into grain boundaries of NC Al has a strengthening effect due to the deceleration of the grain-boundary migration (GBM) and difficulty in the grain-boundary sliding (GBS). The Mg segregation at the boundaries greatly impedes the GBM, but stimulates the development of the GBS. In the NC alloy of Al-Ti, the GBM occurs actively, and the flow-stress values are close to the values characteristic of pure Al.

  8. Loss of coherency of the alpha/beta interface boundary in titanium alloys during deformation

    Science.gov (United States)

    Zherebtsov, Sergey; Salishchev, Gennady; Semiatin, S. Lee

    2010-12-01

    The loss of coherency of interphase boundaries in two-phase titanium alloys during deformation was analyzed. The energy of the undeformed interphase boundary was first determined by means of the van der Merwe model for stepped interfaces. The subsequent loss of coherency was ascribed to the increase of interphase energy due to absorption of lattice dislocations and was quantified by a relation similar to the Read-Shockley equation for low-angle boundaries in single-phase alloys. It was found that interphase boundaries lose their coherency by a strain of approximately 0.5 at T = 800°C.

  9. Effect of grain boundary microstructure on superplastic deformation of Al-Li-Cu-Mg-Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, S.; Yoshimura, T.; Tsurekawa, S.; Watanabe, T. [Tohoku Univ., Sendai (Japan). Dept. of Machine Intelligence and Syst. Eng.

    1999-07-01

    It is common knowledge that grain boundary sliding (GBS) is the most important deformation mechanism for superplastic deformation. In this investigation, Al-Li-Cu-Mg-Zr alloys having two distinct microstructures were produced to examine the effect of grain boundary (GB) microstructure on superplastic deformation. The effective GB microstructure to develop the superplastic deformation is discussed. Specimens with homogeneous and {l_brace}011{r_brace} textured grains, including high frequency of low-angle GBs showed superplastic behavior. The texture was weakened and most of low-angle GBs were changed into random GBs during deformation. Mean grain size increased slightly with deformation. On the other hand, specimens with heterogeneous and randomly oriented grains, with a high frequency of random GBs resulted in nonsuperplastic behavior. This microstructure was essentially unchanged by deformation. Extensive cavitation at GB triple junctions was also observed after superplastic deformation. In particular, cavities were most likely to form at the triple junctions composed of two or more random GBs. We will discuss the development of superplasticity through the optimization of GB microstructures in polycrystalline materials. (orig.)

  10. Analytical solution of conjugate turbulent forced convection boundary layer flow over plates

    Directory of Open Access Journals (Sweden)

    Joneydi Shariatzadeh Omid

    2016-01-01

    Full Text Available A conjugate (coupled forced convection heat transfer from a heated conducting plate under turbulent boundary layer flow is considered. A heated plate of finite thickness is cooled under turbulent forced convection boundary layer flow. Because the conduction and convection boundary layer flow is coupled (conjugated in the problem, a semi-analytical solution based on Differential Transform Method (DTM is presented for solving the non-linear integro-differential equation occurring in the problem. The main conclusion is that in the conjugate heat transfer case the temperature distribution of the plate is flatter than the one in the non-conjugate case. This feature is more pronounced under turbulent flow when compared with the laminar flow.

  11. A closed form large deformation solution of plate bending with surface effects.

    Science.gov (United States)

    Liu, Tianshu; Jagota, Anand; Hui, Chung-Yuen

    2017-01-04

    We study the effect of surface stress on the pure bending of a finite thickness plate under large deformation. The surface is assumed to be isotropic and its stress consists of a part that can be interpreted as a residual stress and a part that stiffens as the surface increases its area. Our results show that residual surface stress and surface stiffness can both increase the overall bending stiffness but through different mechanisms. For sufficiently large residual surface tension, we discover a new type of instability - the bending moment reaches a maximum at a critical curvature. Effects of surface stress on different stress components in the bulk of the plate are discussed and the possibility of self-bending due to asymmetry of the surface properties is also explored. The results of our calculations provide insights into surface stress effects in the large deformation regime and can be used as a test for implementation of finite element methods for surface elasticity.

  12. Propagation of rifting along the Arabia-Somalia Plate Boundary: Into Afar

    Science.gov (United States)

    Manighetti, I.; Tapponnier, P.; Gillot, P. Y.; Jacques, E.; Courtillot, V.; Armijo, R.; Ruegg, J. C.; King, G.

    1998-03-01

    It is generally accepted that the Aden ridge has propagated westward from ˜58°E to the western tip of the Gulf of Aden/Tadjoura, at the edge of Afar. Here, we use new tectonic and geochronological data to examine the geometry and kinematics of deformation related to the penetration of that ridge on dry land in the Republic of Djibouti. We show that it veers northward, forming a narrow zone of dense faulting along the northeastern edge of the Afar depression. The zone includes two volcanic rifts (Asal-Ghoubbet and Manda Inakir), connected to one another and to the submarine part of the ridge by transfer zones. Both rifts are composite, divided into two or three disconnected, parallel, NW-SE striking subrifts, all of which appear to have propagated northwestward. In Asal-Ghoubbet as in Manda Inakir, the subrifts appear to have formed in succession, through north directed jumps from subrifts more farther south. At present, the northernmost subrifts (Manda and Dirko Koma) of the Manda Inakir rift, form the current tip of the northward propagating Arabia-Somalia plate boundary in Afar. We account for most observations by a mechanical model similar to that previously inferred for the Gulf of Aden, in which propagation is governed by the intensity and direction of the minimum horizontal principal stress, σ3. We interpret the northward propagation on land, almost orthogonal to that in the gulf, to be related to necking of the Central Afar lithosphere where it is thinnest. Such necking may be a consequence of differential magmatic thickening, greater in the center of the Afar depression where the Ethiopian hot spot enhanced profuse basaltic effusion and underplating than along the edges of the depression. The model explains why the Aden ridge foregoes its WSW propagation direction, constant from ˜58°E to Asal-Ghoubbet. At a smaller scale, individual rifts and subrifts keep opening perpendicular to the Arabia-Somalia (or Danakil-Somalia) motion vector and propagate

  13. Asymptotic analysis of the equations and boundary conditions of thermoelasticity of micropolar thin plates

    Directory of Open Access Journals (Sweden)

    Vardanyan S. A.

    2007-09-01

    Full Text Available In the framework of the asymmetrical momental micropolar theory in the present work the boundary value problem of thermal stresses in a three-dimensional thin plate with independent fields of displacements and rotations is studied on the basis of asymptotic method. Depending on the values of physical dimensionless constants of the material three applied two-dimensional theories of thermoelasticity of micropolar thin plate are constructed (theories with independent rotations, with constrained rotations and with small shift rigidity.

  14. Dynamic Stationary Response of Reinforced Plates by the Boundary Element Method

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Facundo Sanches

    2007-01-01

    Full Text Available A direct version of the boundary element method (BEM is developed to model the stationary dynamic response of reinforced plate structures, such as reinforced panels in buildings, automobiles, and airplanes. The dynamic stationary fundamental solutions of thin plates and plane stress state are used to transform the governing partial differential equations into boundary integral equations (BIEs. Two sets of uncoupled BIEs are formulated, respectively, for the in-plane state (membrane and for the out-of-plane state (bending. These uncoupled systems are joined to form a macro-element, in which membrane and bending effects are present. The association of these macro-elements is able to simulate thin-walled structures, including reinforced plate structures. In the present formulation, the BIE is discretized by continuous and/or discontinuous linear elements. Four displacement integral equations are written for every boundary node. Modal data, that is, natural frequencies and the corresponding mode shapes of reinforced plates, are obtained from information contained in the frequency response functions (FRFs. A specific example is presented to illustrate the versatility of the proposed methodology. Different configurations of the reinforcements are used to simulate simply supported and clamped boundary conditions for the plate structures. The procedure is validated by comparison with results determined by the finite element method (FEM.

  15. A constitutive model of nanocrystalline metals based on competing grain boundary and grain interior deformation mechanisms

    KAUST Repository

    Gurses, Ercan

    2011-12-01

    In this work, a viscoplastic constitutive model for nanocrystalline metals is presented. The model is based on competing grain boundary and grain interior deformation mechanisms. In particular, inelastic deformations caused by grain boundary diffusion, grain boundary sliding and dislocation activities are considered. Effects of pressure on the grain boundary diffusion and sliding mechanisms are taken into account. Furthermore, the influence of grain size distribution on macroscopic response is studied. The model is shown to capture the fundamental mechanical characteristics of nanocrystalline metals. These include grain size dependence of the strength, i.e., both the traditional and the inverse Hall-Petch effects, the tension-compression asymmetry and the enhanced rate sensitivity. © 2011 Elsevier B.V. All rights reserved.

  16. Evaluation of Transverse Thermal Stresses in Composite Plates Based on First-Order Shear Deformation Theory

    Science.gov (United States)

    Rolfes, R.; Noor, A. K.; Sparr, H.

    1998-01-01

    A postprocessing procedure is presented for the evaluation of the transverse thermal stresses in laminated plates. The analytical formulation is based on the first-order shear deformation theory and the plate is discretized by using a single-field displacement finite element model. The procedure is based on neglecting the derivatives of the in-plane forces and the twisting moments, as well as the mixed derivatives of the bending moments, with respect to the in-plane coordinates. The calculated transverse shear stiffnesses reflect the actual stacking sequence of the composite plate. The distributions of the transverse stresses through-the-thickness are evaluated by using only the transverse shear forces and the thermal effects resulting from the finite element analysis. The procedure is implemented into a postprocessing routine which can be easily incorporated into existing commercial finite element codes. Numerical results are presented for four- and ten-layer cross-ply laminates subjected to mechanical and thermal loads.

  17. Crystallographic Fabrics, Grain Boundary Microstructure and Shape Preferred Orientation of Deformed Banded Iron Formations and their Significance for Deformation Interpretation

    Science.gov (United States)

    Ávila, Carlos Fernando; Graça, Leonardo; Lagoeiro, Leonardo; Ferreira, Filippe

    2016-04-01

    The characterization of grain boundaries and shapes along with crystallographic preferred orientations (CPOs) are a key aspect of investigations of rock microstructures for their correlation with deformation mechanisms. Rapid developments have occurred in the studying rock microstructures due to recent improvements in analytical techniques such as Electron Backscatter Diffraction (EBSD). EBSD technique allows quick automated microtextural characteritzation. The deformed banded iron formations (BIFs) occurring in the Quadrilátero Ferrífero (QF) province in Brazil have been studied extensively with EBSD. All studies have focused mainly in CPOs. The general agreement is that dislocation creep was the dominant process of deformation, for the strong c-axis fabric of hematite crystals. This idea is substantiated by viscoplastic self-consistent models for deformation of hematite. However there are limitations to analyzing natural CPOs alone, or those generated by deformation models. The strong c-axis fabric could be taken as equally powerful an evidence for other known deformation mechanisms. Some grain boundary types in BIFs of the QF are irregular and comprise equant grains in granoblastic texture (Figure 1a). CPOs for this kind are strong and consistent with a predominance of dislocation creep. Others are very regular and long parallel to basal planes of hematites forming large elongated crystals (lepidoblastic texture, Figure 1b). Such crystals are called specularite, and their formation has been previously attributed to dislocation creep. This is erroneous because of the high strains which would be required. Their shape must be due to anisotropic grain growth. Other types lie between the above end-textures. Both types of grain shape microstructures have the same core deformation mechanism. Describing their genetic differences is crucial, since specularite owe its shape to anisotropic grain growth. It is not possible yet to confirm that dislocation creep was the

  18. Evidence for relative motions between the Indian and Australian Plates during the last 20 m.y. from plate tectonic reconstructions: Implications for the deformation of the Indo-Australian Plate

    Science.gov (United States)

    Royer, Jean-Yves; Chang, Ted

    1991-07-01

    We use plate tectonic reconstructions to establish whether motions between India and Australia occurred since chron 18 (43 Ma). We test the Africa/Antarctica/Australia/India plate circuit closure at chrons 5 (10 Ma), 6 (21 Ma) and 13 (36 Ma) using a compilation of magnetic anomalies and fracture zone traces from the Southeast, Southwest, Central Indian and the Carlsberg ridges. Additional reconstructions at chrons 23 (55 Ma) and 26 (61 Ma) are used to estimate the overall motion between India and Australia. Relative motions between the Indian and Australian plates are estimated using the plate circuit India → Africa → Australia. A new statistical approach, based on spherical regression analyses, is used to assess the uncertainty of the "best-fitting" finite rotations from the uncertainties in the data. The uncertainty in a rotation is described by a covariance matrix directly related to the geometry of the reconstructed plate boundary, to the distribution and estimated errors of the data points along it. Our parameterization of the rotations allows for simple combination of the rotation uncertainties along a plate circuit path. Results for chron 5 are remarkably consistent with present-day kinematics in the Indian Ocean, except that the Arabian and Indian plates are found to be separate plates. Comparisons of the motions between the Indian and African plates across the Carlsberg Ridge with that between the Australian and African plates across the Central Indian Ridge evidence a significant counterclockwise rotation of the Australian plate relative to the Indian plate about a pole located in the Central Indian Basin. The determinations are consistent for chrons 26, 13, 6 and 5. Determination at chron 23 is different but questionable due to the small number of available data. We propose two alternative solutions that both predict convergence within the Wharton and Central Indian basins and extension in the vicinity of the Chagos-Laccadive Ridge. The first

  19. The Effects of Aseismic Ridge Collision on Upper Plate Deformation: Cocos Ridge Collision and Deformation of the Western Caribbean

    Science.gov (United States)

    La Femina, P. C.; Govers, R. M. A.; Ruiz, G.; Geirsson, H.; Camacho, E.; Mora-Paez, H.

    2015-12-01

    The collision of the Panamanian isthmus with northwestern South America is thought to have initiated as early as Oligocene - Miocene time (23-25 Ma) based on geologic and geophysical data and paleogeographic reconstructions. This collision was driven by eastward-directed subduction beneath northwestern South America. Cocos - Caribbean convergence along the Middle America Trench, and Nazca - Caribbean oblique convergence along the South Panama Deformed Belt have resulted in complex deformation of the southwestern Caribbean since Miocene - Pliocene time. Subduction and collision of the aseismic Cocos Ridge is thought to have initiated volcanism and uplift of the Cordillera de Talamanca, Costa Rica; 2) Quaternary migration of the volcanic arc toward the back-arc in Costa Rica; 3) Quaternary to present deformation within the Central Costa Rica Deformed Belt; 4) Quaternary to present shortening across the fore-arc Fila Costeña fold and thrust belt and back-arc North Panama Deformed Belt (NPDB); 5) Quaternary to present outer fore-arc uplift of Nicoya Peninsula above the seamount domain, and the Osa and Burica peninsulas above the ridge; and 6) Pleistocene to present northwestward motion of the Central American Fore Arc (CAFA) and northeastward motion of the Panama Region. We investigate the geodynamic effects of Cocos Ridge collision on motion of the Panama Region with a new geodynamic model. The model is compared to a new 1993-2015 GPS-derived three-dimensional velocity field for the western Caribbean and northwestern South America. Specifically, we test the hypotheses that the Cocos Ridge is the main driver for upper plate deformation in the western Caribbean. Our models indicate that Cocos Ridge collision drives northwest-directed motion of the CAFA and the northeast-directed motion of the Panama Region. The Panama Region is driven into the Caribbean across the NPDB and into northwestern South America, which is also converging with the Panama Region, pushing it

  20. New Evidences for Preserved Segmentation of the Alpine-Tethyan Domain in the Iberia-Africa Plate Boundary Region

    Science.gov (United States)

    Fernandez, M.; Torne, M.; Verges, J.; Buffett, G. G.

    2015-12-01

    Based on gravity analysis and previous integrated studies combining potential fields and seismic data, we demonstrate that the Iberia-Africa plate boundary region is characterized by several tectonically inverted transtensional domains inherited from the Jurassic. Gravity data, when filtered for short wavelengths, show conspicuous positive Bouguer anomalies associated with the Gorringe Bank, the Guadalquivir Bank and the Ronda/Beni-Bousera peridotitic massifs. Gravity modelling combined with seismic and geological data shows that the filtered Bouguer anomalies are compatible with relatively high-density and shallow-buried bodies, which correspond to partly serpentinized peridotitic slices with similar densities and geometries as those proved for the Gorringe Bank. The study indicates that the Alpine convergence between Africa and Iberia since Late Cretaceous times reactivated these transtensional domains, which were less deformed westwards and thus preserved their segmentation. The interpretation of these Bouguer anomalies and their distribution substantiates the double-polarity subduction model proposed for the region, and agrees with the present-day seismically diffuse character of the Iberia-Africa plate boundary.

  1. Low-latency high-rate GPS data from the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Anderson, G.; Jackson, M.; Meertens, C.; Stark, K.

    2007-05-01

    Real-time processing of high rate GPS data can give precise (e.g., 5-10 mm for data recorded once per second) recordings of rapid volcanic and seismic deformation. GPS is also an inertial sensor that records ground displacement with very high dynamic range, which allows the use of high rate GPS as a strong-motion seismometer. Such processing applied to low-latency streams of high sample rate GPS provide an emerging tool for earthquake, volcano, and tsunami geodesy and early warning. UNAVCO, as part of the EarthScope Plate Boundary Observatory project, is developing a system to provide such streams from some PBO and other UNAVCO-operated GPS stations, which we call UStream. UStream will be based on the Ntrip standard, a widely used protocol for streaming GNSS data over the Internet. Remote GPS stations will provide a stream of BINEX data at 1 sample/sec to an Ntrip server at UNAVCO's Boulder offices, while at the same time recording data locally in the event of communications failure. Once in Boulder, the data will be forked into three output streams: BINEX files stored at the UNAVCO archive and streams of data in BINEX and RTCM format. These data will flow to an Ntrip broadcaster that will distribute data to Ntrip clients, which can be anything from epoch-by-epoch processing systems to external data archiving systems. Data will flow through this system with no artificial latency and will be freely available to the community for use in scientific research.

  2. High-Resolution LiDAR Topography of the Plate-Boundary Faults in Northern California

    Science.gov (United States)

    Prentice, C. S.; Phillips, D. A.; Furlong, K. P.; Brown, A.; Crosby, C. J.; Bevis, M.; Shrestha, R.; Sartori, M.; Brocher, T. M.; Brown, J.

    2007-12-01

    GeoEarthScope acquired more than 1500 square km of airborne LiDAR data in northern California, providing high-resolution topographic data of most of the major strike-slip faults in the region. The coverage includes the San Andreas Fault from its northern end near Shelter Cove to near Parkfield, as well as the Rodgers Creek, Maacama, Calaveras, Green Valley, Paicines, and San Gregorio Faults. The Hayward fault was added with funding provided by the US Geological Survey, the City of Berkeley, and the San Francisco Public Utilities Commission. Data coverage is typically one kilometer in width, centered on the fault. In areas of particular fault complexity the swath width was increased to two kilometers, and in selected areas swath width is as wide as five kilometers. A five-km-wide swath was flown perpendicular to the plate boundary immediately south of Cape Mendocino to capture previously unidentified faults and to understand off-fault deformation associated with the transition zone between the transform margin and the Cascadia subduction zone. The data were collected in conjunction with an intensive GPS campaign designed to improve absolute data accuracy and provide quality control. Data processing to classify the LiDAR point data by return type allows users to filter out vegetation and produce high-resolution DEMs of the ground surface beneath forested regions, revealing geomorphic features along and adjacent to the faults. These data will allow more accurate mapping of fault traces in regions where the vegetation canopy has hampered this effort in the past. In addition, the data provide the opportunity to locate potential sites for detailed paleoseismic studies aimed at providing slip rates and event chronologies. The GeoEarthScope LiDAR data will be made available via an interactive data distribution and processing workflow currently under development.

  3. Fault and graben growth along active magmatic divergent plate boundaries in Iceland and Ethiopia

    KAUST Repository

    Trippanera, D.

    2015-10-08

    Recent studies highlight the importance of annual-scale dike-induced rifting episodes in developing normal faults and graben along the active axis of magmatic divergent plate boundaries (MDPB). However, the longer-term (102-105 years) role of diking on the cumulative surface deformation and evolution of MDPB is not yet well understood. To better understand the longer-term normal faults and graben along the axis of MDPB, we analyze fissure swarms in Iceland and Ethiopia. We first focus on the simplest case of immature fissure swarms, with single dike-fed eruptive fissures; these consist of a <1 km wide graben bordered by normal faults with displacement up to a few meters, consistent with theoretical models and geodetic data. A similar structural pattern is found, with asymmetric and multiple graben, within wider mature fissure swarms, formed by several dike-fed eruptive fissures. We then consider the lateral termination of normal faults along these graben, to detect their upward or downward propagation. Most faults terminate as open fractures on flat surface, suggesting downward fault propagation; this is consistent with recent experiments showing dike-induced normal faults propagating downward from the surface. However, some normal faults also terminate as open fractures on monoclines, which resemble fault propagation folds; this suggests upward propagation of reactivated buried faults, promoted by diking. These results suggest that fault growth and graben development, as well as the longer-term evolution of the axis of MDPB, may be explained only through dike emplacement and that any amagmatic faulting is not necessary.

  4. The influence of circuit inductance on the energy characteristics of electric discharge and deformation of plates in water

    Science.gov (United States)

    Kosenkov, V. M.; Bychkov, V. M.

    2017-08-01

    We have experimentally studied the influence of discharge-circuit inductance on the efficiency of conversion of energy stored in a capacitor bank, evolved in the electric-discharge channel in water, and spent for the resulting plastic deformation of plates. It is established for the first time that a growth in inductance of the discharge circuit produces a positive effect on the deformation of plates by increasing the amount of energy spent in this process.

  5. Deliverable 4.6: Data of the guided ditching tests for permanent deformation (aluminium and composite plates)

    OpenAIRE

    Iafrati, Alessandro; Olivieri, Flavio; Santos, Victor Hugo; Grizzi, Silvano; Fortunati, Marco; Ortolani, Fabrizio; Mauro, Luca

    2014-01-01

    In the present report the data of the guided ditching tests of the plates which were expected to undergo permanent deformations are presented and discussed briefly. Before going into the details of the data, some aspects of the experimental setup which were specific for tests on the deformable plates are provided. The last section is devoted to the presentation of the data of the DASSAULT specimen tested at the high speed ditching facility.

  6. A comparison of boundary element and finite element methods for modeling axisymmetric polymeric drop deformation

    NARCIS (Netherlands)

    Hooper, Russell; Toose, E.M.; Macosko, Christopher W.; Derby, Jeffrey J.

    2001-01-01

    A modified boundary element method (BEM) and the DEVSS-G finite element method (FEM) are applied to model the deformation of a polymeric drop suspended in another fluid subjected to start-up uniaxial extensional flow. The effects of viscoelasticity, via the Oldroyd-B differential model, are

  7. Evolving seismogenic plate boundary megathrust and mega-splay faults in subduction zone (Invited)

    Science.gov (United States)

    Kimura, G.; Hamahashi, M.; Fukuchi, R.; Yamaguchi, A.; Kameda, J.; Kitamura, Y.; Hashimoto, Y.; Hamada, Y.; Saito, S.; Kawasaki, R.

    2013-12-01

    Understanding the fault mechanism and its relationship to the sesimo-tsunamigenesis is a key of the scientific targets of subduction zone and therefore NantroSEIZE project of IODP and future new drilling project of International Ocean Discovery Program keeps focusing on that. Mega-splay fault branched from plate boundary megathrust in subduction zone is located around the border between outer and inner wedges and is considered to cause great earthquake and tsunami such as 1960 Alaska earthquake, 1944 and 1946 Nankai-Tonankai earthquakes, and 2004 Sumatra earthquakes. Seismic reflection studies for the mega-splay fault in 2D and 3D in the Nankai forearc present the reflector with negative or positive polarities with various amplitudes and suggest complicated petrophysical properties and condition of the fault and its surroundings. The Nankai mega-splay fault at a depth of ~5km is going to be drilled and cored by NantroSEIZE experiments and is expected for great progress of understanding of the fault mechanics. Before drilling the really targeted seismogenic fault, we are conducting many exercises of geophysical and geological observations. The core-log-seismic integrated exercise for the exhumed mega-splay fault by drilling was operated for the Nobeoka thrust in the Shimanto Belt, Kyushu, Japan. The Nobeoka thrust was once buried in the depth >~10km and suffered maximum temperature >~300 dgree C. As the core recovery is ~99%, perfect correlation between the core and logging data is possible. Thickness of the fault zone is >200 m with a ~50 cm thick central fault core dividing the phyllitic hanging wall and the footwall of broken-melange like cataclasite. A-few-meter-thick discrete damage zones with fault cores are recognized by difference in physical properties and visual deformation textures at several horizons in the fault zone. Host rocks for those damaged zones are completely lithified cataclasites with abundant mineral veins, which record the older and deeper

  8. Analysis of Blasius Equation for Flat-Plate Flow with Infinite Boundary Value

    DEFF Research Database (Denmark)

    Miansari, M. O.; Miansari, M. E.; Barari, Amin;

    2010-01-01

    This paper applies the homotopy perturbation method (HPM) to determine the well-known Blasius equation with infinite boundary value for Flat-plate Flow. We study here the possibility of reducing the momentum and continuity equations to ordinary differential equations by a similarity transformatio...

  9. Exact controllability of the Euler-Bernoulli plate with variable coefficients and simply supported boundary condition

    Directory of Open Access Journals (Sweden)

    Fengyan Yang

    2016-09-01

    Full Text Available This article studies the exact controllability of an Euler-Bernoulli plate equation with variable coefficients, subject to the simply supported boundary condition. By the Riemannian geometry approach, the duality method, the multiplier technique, and the compactness-uniqueness argument, we establish the corresponding observability inequality and obtain the exact controllability results.

  10. AN EFFECTIVE BOUNDARY ELEMENT METHOD FOR ANALYSIS OF CRACK PROBLEMS IN A PLANE ELASTIC PLATE

    Institute of Scientific and Technical Information of China (English)

    YAN Xiang-qiao

    2005-01-01

    A simple and effective boundary element method for stress intensity factor calculation for crack problems in a plane elastic plate is presented. The boundary element method consists of the constant displacement discontinuity element presented by Crouch and Starfield and the crack-tip displacement discontinuity elements proposed by YAN Xiangqiao. In the boundary element implementation the left or the right crack-tip displacement discontinuity element was placed locally at the corresponding left or right each crack tip on top of the constant displacement discontinuity elements that cover the entire crack surface and the other boundaries. Test examples ( i. e. , a center crack in an infinite plate under tension, a circular hole and a crack in an infinite plate under tension) are included to illustrate that the numerical approach is very simple and accurate for stress intensity factor calculation of plane elasticity crack problems. In addition, specifically, the stress intensity factors of branching cracks emanating from a square hole in a rectangular plate under biaxial loads were analysed. These numerical results indicate the present numerical approach is very effective for calculating stress intensity factors of complex cracks in a 2-D finite body, and are used to reveal the effect of the biaxial loads and the cracked body geometry on stress intensity factors.

  11. Analysis of the Mechanism of Longitudinal Bending Deformation Due to Welding in a Steel Plate by Using a Numerical Model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Rae; Yan, Jieshen; Kim, Jae-Woong [Yeungnam Univ., Gyeongsan (Korea, Republic of); Song, Gyu Yeong [Gyeongbuk Hybrid Technology Institute, Yeongcheon (Korea, Republic of)

    2017-01-15

    Welding deformation is a permanent deformation that is caused in structures by welding heat. Welding distortion is the primary cause of reduced productivity, due to welded structural strength degradation, low dimensional accuracy, and appearance. As a result, research and numerous experiments are being carried out to control welding deformation. The aim of this study is to analyze the mechanism of longitudinal bending deformation due to welding. Welding experiments and numerical analyses were performed for this study. The welding experiments were performed on 4 mm and 8.5 mm thickness steel plates, and the numerical analysis was conducted on the welding deformation using the FE software MSC.marc.

  12. What can we Learn From Small Non-Recoverable Strains at Plate Boundaries?

    Science.gov (United States)

    Lewis, J. C.; Pluhar, C. J.

    2003-12-01

    Background seismicity carries often overlooked information about how the crust responds to plate motions. Integrating focal mechanisms for background seismicity with (1) geologic observations, and (2) geodetic constraints, is critical to establishing a better understanding of both the rock record and contemporary deformation. Treating the crust as a micropolar continuum it is possible to constrain not only the orientations and relative magnitudes of the principal strains but also the vorticity of crustal blocks with respect to the large-scale continuum. We show the utility of this approach with examples from the Cascadia margin and the Coso Range (within the Eastern California shear zone). In the upper crust of the Cascadia margin, seismogenic strain appears to be dominated by accommodation of motion of the Oregon forearc block. This suggests that the shallow crust is responding to long-term motion of the Oregon forearc rather than the interseismic locking of the subduction megathrust. In the area west of Mt. Rainier, this response is marked by non-zero relative vorticity in a regime of N-S shortening and crustal thickening. To date, geologic studies necessary to evaluate the significance of this vorticity have not been completed. In contrast within the Coso Range of California, seismogenic strain at Wild Horse Mesa indicates a component of relative vorticity that is broadly consistent with paleomagnetically constrained finite rotations of the ca. 3 Ma lava flows that compose the mesa. This area is centered at a right-releasing step in the Eastern California shear zone and thus is experiencing active transtension. Stratigraphic constraints have been used to suggest that significant dextral shearing in this region initiated ca. 3.5-2 Ma. The seismogenic response to transtension is depth-dependent plane strain with crustal thinning above 5 km and horizontal dextral shearing from 5-8 km. Both structural levels indicate subhorizontal E-W maximum stretching. Relative

  13. How does the 2010 El Mayor - Cucapah Earthquake Rupture Connect to the Southern California Plate Boundary Fault System

    Science.gov (United States)

    Donnellan, A.; Ben-Zion, Y.; Arrowsmith, R.

    2016-12-01

    The Pacific - North American plate boundary in southern California is marked by several major strike slip faults. The 2010 M7.2 El Mayor - Cucapah earthquake ruptured 120 km of upper crust in Baja California to the US-Mexico border. The earthquake triggered slip along an extensive network of faults in the Salton Trough from the Mexican border to the southern end of the San Andreas fault. Earthquakes >M5 were triggered in the gap between the Laguna Salada and Elsinore faults at Ocotillo and on the Coyote Creek segment of the San Jacinto fault 20 km northwest of Borrego Springs. UAVSAR observations, collected since October of 2009, measure slip associated with the M5.7 Ocotillo aftershock with deformation continuing into 2014. The Elsinore fault has been remarkably quiet, however, with only M5.0 and M5.2 earthquakes occurring on the Coyote Mountains segment of the fault in 1940 and 1968 respectively. In contrast, the Imperial Valley has been quite active historically with numerous moderate events occurring since 1935. Moderate event activity is increasing along the San Jacinto fault zone (SJFZ), especially the trifurcation area, where 6 of 12 historic earthquakes in this 20 km long fault zone have occurred since 2000. However, no recent deformation has been detected using UAVSAR measurements in this area, including the recent M5.2 June 2016 Borrego earthquake. Does the El Mayor - Cucapah rupture connect to and transfer stress primarily to a single southern California fault or several? What is its role relative to the background plate motion? UAVSAR observations indicate that the southward extension of the Elsinore fault has recently experienced the most localized deformation. Seismicity suggests that the San Jacinto fault is more active than neighboring major faults, and geologic evidence suggests that the Southern San Andreas fault has been the major plate boundary fault in southern California. Topographic data with 3-4 cm resolution using structure from motion from

  14. Propagation of rifting along the Arabia-Somalia Plate Boundary: The Gulfs of Aden and Tadjoura

    Science.gov (United States)

    Manighetti, Isabelle; Tapponnier, Paul; Courtillot, Vincent; Gruszow, Sylvie; Gillot, Pierre-Yves

    1997-02-01

    The localization and propagation of rifting between Arabia and Somalia are investigated by assessing the deformation geometry and kinematics at different scales between the eastern Gulf of Aden and the Gulf of Tadjoura, using bathymetric, magnetic, seismological, and structural evidence. Large-scale, southwestward propagation of the Aden ridge, markedly oblique to the Arabia-Somalia relative motion vector, began about 30 Myr ago between the Error and Sharbithat ridges. It was an episodic process, with stages of rapid propagation, mostly at rates >10 cm/yr, interrupted by million year pauses on transverse discontinuities coinciding with rheological boundaries between different crustal provinces of the Arabia-Somalia plate. The longest pause was at the Shukra-El Sheik discontinuity (≈45°E), where the ridge tip stalled for ≈13 Myr, between ≈17 and ≈4 Ma. West of that discontinuity, rifting and spreading took place at an azimuth (≈N25°±10°E) and rate (1.2±0.3 cm/yr) different from those of the global Arabia-Somalia motion vector (≈N39°, ≈1.73 cm/yr), implying an additional component of movement (N65°±10°E, 0.7±0.2 cm/yr) due to rotation of the Danakil microplate. At Shukra-El Sheik, the typical oceanic ridge gives way to a narrow, WSW trending axial trough, resembling a large fissure across a shallow shelf. This trough is composed of about eight rift segments, which result from normal faulting and fissuring along N110°-N130°E trends. All the segments step to the left southwestward, mostly through oblique transfer zones with en échelon normal faults. Only two segments show clear, significant overlap. There is one clear transform, the Maskali fault, between the Obock and Tadjoura segments. The latter segment, which encroaches onland, is composed of two parallel subrifts (Iboli, Ambabbo) that propagated northwestward and formed in succession. The most recent, southwestern subrift (Ambabbo) represents the current tip of the Aden ridge. We propose

  15. Learning the dynamics and time-recursive boundary detection of deformable objects.

    Science.gov (United States)

    Sun, Walter; Cetin, Müjdat; Chan, Raymond; Willsky, Alan S

    2008-11-01

    We propose a principled framework for recursively segmenting deformable objects across a sequence of frames. We demonstrate the usefulness of this method on left ventricular segmentation across a cardiac cycle. The approach involves a technique for learning the system dynamics together with methods of particle-based smoothing as well as nonparametric belief propagation on a loopy graphical model capturing the temporal periodicity of the heart. The dynamic system state is a low-dimensional representation of the boundary, and the boundary estimation involves incorporating curve evolution into recursive state estimation. By formulating the problem as one of state estimation, the segmentation at each particular time is based not only on the data observed at that instant, but also on predictions based on past and future boundary estimates. Although this paper focuses on left ventricle segmentation, the method generalizes to temporally segmenting any deformable object.

  16. Two-Dimensional Large Deformation Finite Element Analysis for the Pulling-up of Plate Anchor

    Institute of Scientific and Technical Information of China (English)

    WANG Dong; HU Yu-xia; JIN Xia

    2006-01-01

    Based on mesh regeneration and stress interpolation from an old mesh to a new one, a large deformation finite element model is developed for the study of the behaviour of circular plate anchors subjected to uplift loading. For the determination of the distributions of stress components across a clay foundation, the Recovery by Equilibrium in Patches is extended to plastic analyses. ABAQUS, a commercial finite element package, is customized and linked into our program so as to keep automatic and efficient running of large deformation calculation. The quality of stress interpolation is testified by evaluations of Tresca stress and nodal reaction forces. The complete pulling-up processes of plate anchors buried in homogeneous clay are simulated, and typical pulling force-displacement responses of a deep anchor and a shallow anchor are compared. Different from the results of previous studies, large deformation analysis is of the capability of estimating the breakaway between the anchor bottom and soils. For deep anchors, the variation of mobilized uplift resistance with anchor settlement is composed of three stages, and the initial buried depths of anchors affect the separation embedment slightly. The uplift bearing capacity of deep anchors is usually higher than that of shallow anchors.

  17. Triassic to Cenozoic multi-stage intra-plate deformation focused near the Bogd Fault system, Gobi Altai, Mongolia

    NARCIS (Netherlands)

    Van Hinsbergen, Douwe J J; Cunningham, Dickson; Straathof, Gijsbert B.; Ganerød, Morgan; Hendriks, Bart W H; Dijkstra, Arjan H.

    2015-01-01

    The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the mid-Mesozoic, yet has experienced episodic phases of deformation since that time. In this paper, we document field evidence to characterize and date the intra-plate tectonic history of the Gobi Altai region

  18. Seismic evidence for sharp lithosphere-asthenosphere boundaries of oceanic plates.

    Science.gov (United States)

    Kawakatsu, Hitoshi; Kumar, Prakash; Takei, Yasuko; Shinohara, Masanao; Kanazawa, Toshihiko; Araki, Eiichiro; Suyehiro, Kiyoshi

    2009-04-24

    The mobility of the lithosphere over a weaker asthenosphere constitutes the essential element of plate tectonics, and thus the understanding of the processes at the lithosphere-asthenosphere boundary (LAB) is fundamental to understand how our planet works. It is especially so for oceanic plates because their relatively simple creation and evolution should enable easy elucidation of the LAB. Data from borehole broadband ocean bottom seismometers show that the LAB beneath the Pacific and Philippine Sea plates is sharp and age-dependent. The observed large shear wave velocity reduction at the LAB requires a partially molten asthenosphere consisting of horizontal melt-rich layers embedded in meltless mantle, which accounts for the large viscosity contrast at the LAB that facilitates horizontal plate motions.

  19. Identification and Estimation of Postseismic Deformation: Implications for Plate Motion Models, Models of the Earthquake Cycle, and Terrestrial Reference Frame Definition

    Science.gov (United States)

    Kedar, S.; Bock, Y.; Moore, A. W.; Argus, D. F.; Fang, P.; Liu, Z.; Haase, J. S.; Su, L.; Owen, S. E.; Goldberg, D.; Squibb, M. B.; Geng, J.

    2015-12-01

    Postseismic deformation indicates a viscoelastic response of the lithosphere. It is critical, then, to identify and estimate the extent of postseismic deformation in both space and time, not only for its inherent information on crustal rheology and earthquake physics, but also since it must considered for plate motion models that are derived geodetically from the "steady-state" interseismic velocities, models of the earthquake cycle that provide interseismic strain accumulation and earthquake probability forecasts, as well as terrestrial reference frame definition that is the basis for space geodetic positioning. As part of the Solid Earth Science ESDR System) SESES project under a NASA MEaSUREs grant, JPL and SIO estimate combined daily position time series for over 1800 GNSS stations, both globally and at plate boundaries, independently using the GIPSY and GAMIT software packages, but with a consistent set of a prior epoch-date coordinates and metadata. The longest time series began in 1992, and many of them contain postseismic signals. For example, about 90 of the global GNSS stations out of more than 400 that define the ITRF have experienced one or more major earthquakes and 36 have had multiple earthquakes; as expected, most plate boundary stations have as well. We quantify the spatial (distance from rupture) and temporal (decay time) extent of postseismic deformation. We examine parametric models (log, exponential) and a physical model (rate- and state-dependent friction) to fit the time series. Using a PCA analysis, we determine whether or not a particular earthquake can be uniformly fit by a single underlying postseismic process - otherwise we fit individual stations. Then we investigate whether the estimated time series velocities can be directly used as input to plate motion models, rather than arbitrarily removing the apparent postseismic portion of a time series and/or eliminating stations closest to earthquake epicenters.

  20. The potential link between high angle grain boundary morphology and grain boundary deformation in a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Carter, Jennifer L.W., E-mail: jennifer.w.carter@case.edu [Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 44321 (United States); Sosa, John M. [Center for Accelerated Maturation of Materials, The Ohio State University, Columbus, OH 44321 (United States); Shade, Paul A. [Air Force Research Laboratory, Materials & Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Dayton, OH 45433 (United States); Fraser, Hamish L. [Center for Accelerated Maturation of Materials, The Ohio State University, Columbus, OH 44321 (United States); Uchic, Michael D. [Air Force Research Laboratory, Materials & Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Dayton, OH 45433 (United States); Mills, Michael J. [Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 44321 (United States)

    2015-07-29

    Focused ion beam (FIB) based serial sectioning was utilized to characterize the morphology of two high angle grain boundaries (HAGB) in a nickel based superalloy, one that experienced grain boundary sliding (GBS) and the other experienced strain accumulation, during elevated temperature constant stress loading conditions. A custom script was utilized to serial section and collect ion-induced secondary electron images from the FIB-SEM system. The MATLAB based MIPAR{sup TM} software was utilized to align, segment and reconstruct 3D volumes from the sectioned images. Analysis of the 3D data indicates that the HAGB that exhibited GBS had microscale curvature that was planar in nature, and local serrations on the order of ±150 nm. In contrast, the HAGB that exhibited strain accumulation was not planar and had local serrations an order of magnitude greater than the other grain boundary. It is hypothesized that the serrations and the local grain boundary network are key factors in determining which grain boundaries experience GBS during creep deformation.

  1. Discovering Plate Boundaries Update: Builds Content Knowledge and Models Inquiry-based Learning

    Science.gov (United States)

    Sawyer, D. S.; Pringle, M. S.; Henning, A. T.

    2009-12-01

    Discovering Plate Boundaries (DPB) is a jigsaw-structured classroom exercise in which students explore the fundamental datasets from which plate boundary processes were discovered. The exercise has been widely used in the past ten years as a classroom activity for students in fifth grade through high school, and for Earth Science major and general education courses in college. Perhaps more importantly, the exercise has been used extensively for professional development of in-service and pre-service K-12 science teachers, where it simultaneously builds content knowledge in plate boundary processes (including natural hazards), models an effective data-rich, inquiry-based pedagogy, and provides a set of lesson plans and materials which teachers can port directly into their own classroom (see Pringle, et al, this session for a specific example). DPB is based on 4 “specialty” data maps, 1) earthquake locations, 2) modern volcanic activity, 3) seafloor age, and 4) topography and bathymetry, plus a fifth map of (undifferentiated) plate boundary locations. The jigsaw is structured so that students are first split into one of the four “specialties,” then re-arranged into groups with each of the four specialties to describe the boundaries of a particular plate. We have taken the original DPB materials, used the latest digital data sets to update all the basic maps, and expanded the opportunities for further student and teacher learning. The earthquake maps now cover the recent period including the deadly Banda Aceh event. The topography/bathymetry map now has global coverage and uses ice-free elevations, which can, for example, extend to further inquiry about mantle viscosity and loading processes (why are significant portions of the bedrock surface of Greenland and Antarctica below sea level?). The volcanic activity map now differentiates volcano type and primary volcanic lithology, allowing a more elaborate understanding of volcanism at different plate boundaries

  2. Free Vibration and Bending Behaviour of CNT Reinforced Composite Plate using Different Shear Deformation Theory

    Science.gov (United States)

    Mehar, K.; Panda, S. K.

    2016-02-01

    In the present study, the free vibration and the bending behaviour of carbon nanotube reinforced composite plate are computed using three different shear deformation theories under thermal environment. The material properties of carbon nanotube and matrix are assumed to be temperature-dependent, and the extended rule of mixture is used to compute the effectivematerial properties of the composite plate. The convergence and validity of the present modelalso have been checked by computing the wide variety of the numerical example. The applicability of the proposed higher-order models has been highlighted by solving the wide variety of examples for different geometrical and material parameters underelevated thermal environment.The responses are also examined using the simulation model developed in commercial finite element package (ANSYS).

  3. Intraplate deformation, stress in the lithosphere and the driving mechanism for plate motions

    Science.gov (United States)

    Albee, Arden L.

    1993-01-01

    The initial research proposed was to use the predictions of geodynamical models of mantle flow, combined with geodetic observations of intraplate strain and stress, to better constrain mantle convection and the driving mechanism for plate motions and deformation. It is only now that geodetic observations of intraplate strain are becoming sufficiently well resolved to make them useful for substantial geodynamical inference to be made. A model of flow in the mantle that explains almost 90 percent of the variance in the observed longwavelength nonhydrostatic geoid was developed.

  4. Two-Dimensional Boundary Element Method Application for Surface Deformation Modeling around Lembang and Cimandiri Fault, West Java

    Science.gov (United States)

    Mahya, M. J.; Sanny, T. A.

    2017-04-01

    Lembang and Cimandiri fault are active faults in West Java that thread people near the faults with earthquake and surface deformation risk. To determine the deformation, GPS measurements around Lembang and Cimandiri fault was conducted then the data was processed to get the horizontal velocity at each GPS stations by Graduate Research of Earthquake and Active Tectonics (GREAT) Department of Geodesy and Geomatics Engineering Study Program, ITB. The purpose of this study is to model the displacement distribution as deformation parameter in the area along Lembang and Cimandiri fault using 2-dimensional boundary element method (BEM) using the horizontal velocity that has been corrected by the effect of Sunda plate horizontal movement as the input. The assumptions that used at the modeling stage are the deformation occurs in homogeneous and isotropic medium, and the stresses that acted on faults are in elastostatic condition. The results of modeling show that Lembang fault had left-lateral slip component and divided into two segments. A lineament oriented in southwest-northeast direction is observed near Tangkuban Perahu Mountain separating the eastern and the western segments of Lembang fault. The displacement pattern of Cimandiri fault shows that Cimandiri fault is divided into the eastern segment with right-lateral slip component and the western segment with left-lateral slip component separated by a northwest-southeast oriented lineament at the western part of Gede Pangrango Mountain. The displacement value between Lembang and Cimandiri fault is nearly zero indicating that Lembang and Cimandiri fault are not connected each other and this area is relatively safe for infrastructure development.

  5. The EarthScope Plate Boundary Observatory (PBO) Facility: Innovations, Transformations, and Impact

    Science.gov (United States)

    Jackson, M. E.; Mencin, D.; Feaux, K.

    2013-12-01

    processing procedures that allowed the project to deal with a compressed installation time line and the varying climactic and geological terrains in the Western US. The science that has come from the PBO deployments includes not only estimates of the secular deformation field across important structures in the active Western US but has provided a full kinematic and dynamic picture of the Pacific and North American Plate boundary interaction. The data registered from the PBO network has been used in diverse studies including determination of the asthenospheric density, temperature, and elastic moduli beneath the Western US (Ito and Simons, 2011), snow depth sensing using GPS multipath (Larson and Nievinski, 2013), continuous monitoring of the horizontal displacement gradient tensor field in Southern California (Holt and Shcherbenko, 2013), and using strainmeter data to constrain the magma reservoir beneath the Yellowstone (Luttrell, 2013). There is little doubt that the EarthScope PBO has met and exceeded its science goals, however what is exciting and transformative is the science that has resulted from the signals and the noise found in between these broad science goals.

  6. Long-lived force patterns and deformation waves at repulsive epithelial boundaries

    Science.gov (United States)

    Rodríguez-Franco, Pilar; Brugués, Agustí; Marín-Llauradó, Ariadna; Conte, Vito; Solanas, Guiomar; Batlle, Eduard; Fredberg, Jeffrey J.; Roca-Cusachs, Pere; Sunyer, Raimon; Trepat, Xavier

    2017-10-01

    For an organism to develop and maintain homeostasis, cell types with distinct functions must often be separated by physical boundaries. The formation and maintenance of such boundaries are commonly attributed to mechanisms restricted to the cells lining the boundary. Here we show that, besides these local subcellular mechanisms, the formation and maintenance of tissue boundaries involves long-lived, long-ranged mechanical events. Following contact between two epithelial monolayers expressing, respectively, EphB2 and its ligand ephrinB1, both monolayers exhibit oscillatory patterns of traction forces and intercellular stresses that tend to pull cell-matrix adhesions away from the boundary. With time, monolayers jam, accompanied by the emergence of deformation waves that propagate away from the boundary. This phenomenon is not specific to EphB2/ephrinB1 repulsion but is also present during the formation of boundaries with an inert interface and during fusion of homotypic epithelial layers. Our findings thus unveil a global physical mechanism that sustains tissue separation independently of the biochemical and mechanical features of the local tissue boundary.

  7. Validation of an immersed thick boundary method for simulating fluid-structure interactions of deformable membranes

    Science.gov (United States)

    Sigüenza, J.; Mendez, S.; Ambard, D.; Dubois, F.; Jourdan, F.; Mozul, R.; Nicoud, F.

    2016-10-01

    This paper constitutes an extension of the work of Mendez et al. (2014) [36], for three-dimensional simulations of deformable membranes under flow. An immersed thick boundary method is used, combining the immersed boundary method with a three-dimensional modeling of the structural part. The immersed boundary method is adapted to unstructured grids for the fluid resolution, using the reproducing kernel particle method. An unstructured finite-volume flow solver for the incompressible Navier-Stokes equations is coupled with a finite-element solver for the structure. The validation process relying on a number of test cases proves the efficiency of the method, and its robustness is illustrated when computing the dynamics of a tri-leaflet aortic valve. The proposed immersed thick boundary method is able to tackle applications involving both thin and thick membranes/closed and open membranes, in significantly high Reynolds number flows and highly complex geometries.

  8. Characterizing the boundary lateral to the shear direction of deformation twins in magnesium

    Science.gov (United States)

    Liu, Y.; Li, N.; Shao, S.; Gong, M.; Wang, J.; McCabe, R. J.; Jiang, Y.; Tomé, C. N.

    2016-06-01

    The three-dimensional nature of twins, especially the atomic structures and motion mechanisms of the boundary lateral to the shear direction of the twin, has never been characterized at the atomic level, because such boundary is, in principle, crystallographically unobservable. We thus refer to it here as the dark side of the twin. Here, using high-resolution transmission electron microscopy and atomistic simulations, we characterize the dark side of deformation twins in magnesium. It is found that the dark side is serrated and comprised of coherent twin boundaries and semi-coherent twist prismatic-prismatic boundaries that control twin growth. The conclusions of this work apply to the same twin mode in other hexagonal close-packed materials, and the conceptual ideas discussed here should hold for all twin modes in crystalline materials.

  9. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    Directory of Open Access Journals (Sweden)

    Mohammed J Uddin

    Full Text Available Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement.

  10. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    Science.gov (United States)

    Uddin, Mohammed J; Khan, Waqar A; Ismail, Ahmed I

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement.

  11. The Influence of Flexibility Coefficient on the Size of Internal Forces and Deformations in Circular Plates on Elastic Medium

    Directory of Open Access Journals (Sweden)

    Şandru Mirela

    2016-09-01

    Full Text Available This paper presents an analytical study which deals with the behavior of the circular plates in bending theory, considering the soil-structure interaction under Winkler's hypothesis. It was intended to illustrate the variation of internal forces and deformations according to the flexibility coefficient of plates considering three models: a fixed solid circular plate subjected to a uniformly distributed load, a fixed solid circular plate acted by a displacement applied on the exterior contour and a solid plate subjected to a temperature gradient. For this study the computation relations were written as a product between a dimensional and a non-dimensional factor, the last one indicating the variation of internal forces and deformations. For each type of action there are presented results obtained using the finite element method to illustrate the differences between this method and the analytical computation.

  12. Alternate model of Chladni figures for the circular homogenous thin plate case with open boundaries

    Science.gov (United States)

    Trejo-Mandujano, H. A.; Mijares-Bernal, G.; Ordoñez-Casanova, E. G.

    2015-01-01

    The wave equation is a direct but a complex approach to solve analytically for the Chladni figures, mainly because of the complications that non-smooth and open boundary conditions impose. In this paper, we present an alternate solution model based on the principle of Huygens-Fresnel and on the ideas of Bohr for the hydrogen atom. The proposed model has been implemented numerically and compared, with good agreement, to our own experimental results for the case of a thin homogenous circular plate with open boundaries.

  13. STRESS INTENSITY FACTORS FOR A FINITE PLATE WITH AN INCLINED CRACK BY BOUNDARY COLLOCATION

    Institute of Scientific and Technical Information of China (English)

    Xing Li; Xuemei You

    2005-01-01

    In this paper, we combine the Muskhelishvili's complex variable method and boundary collocation method, and choose a set of new stress function based on the stress boundary condition of crack surface,the higher precision and less computation are reached. This method is applied to calculating the stress intensity factor for a finite plate with an inclined crack. The influence of θ (the obliquity of crack) on the stress intensity factors, as well as the number of summation terms on the stress intensity factor are studied and graphically represented.

  14. A new technique for monitoring inhomogeneous deformation during flyer plate impact

    Science.gov (United States)

    Walker, James D.; Grosch, Donald J.; Chocron, Sidney; Dannemann, Kathryn A.; Bigger, Rory P.; Moore, Thomas Z.; Kirchdoerfer, Trenton T.

    2017-01-01

    A new and unique experimental configuration was developed and demonstrated to measure the inhomogeneous deformation of heterogeneous materials during flyer plate impact tests. Flyer plate experiments were performed on a granite material with a small scale structure; strain rates ranged from 105 to 107 s-1. A cross section of an impacted target was monitored and photographed during, and immediately following, passage of the shock wave through the material. Up to fourteen images were taken during passage of the shock wave. This was accomplished using an ultra-high speed Imacon camera with very short exposure times; for example, in one experiment the exposure time was 5 nanoseconds with a framing rate of 5 million frames per second. Continuous wave lasers were used as the illumination source. Edge and notch filters were used to lessen the intensity of the impact flash in the image. The photographic data was analyzed using a digital image correlation (DIC) system. These experiments examined inhomogeneous deformation on a cut plane within an inhomogeneous geological (granite) target.

  15. Plate Boundary Observatory Nucleus Education and Outreach: Bringing GPS and Data- Rich Activities Into College and Secondary Earth Science Classrooms

    Science.gov (United States)

    Walker, B.; Eriksson, S. C.

    2006-05-01

    Incorporating scientific data into the curriculum provides students with insight into elements of the scientific process such as developing questions and hypotheses, understanding how data are collected, evaluating data quality and limitations, and formulating conclusions based on scientific results (Manduca et al., 2003.) UNAVCO, a geodetic consortium and co-administrator of the Plate Boundary Observatory Nucleus project, seeks to increase public appreciation and understanding of Earth deformation processes and their societal relevance through education and outreach. To that end, we are developing place-based instructional materials for college and secondary Earth science classrooms in which GPS data are used to teach students about plate tectonics. To assess the needs of our users, we conducted interviews with college geoscience faculty from a variety of institution types and focus groups with secondary Earth science teachers to solicit feedback on the types of educational materials that they would likely use in their classrooms. We are engaging members of the scientific and educational communities to develop the materials and are catering the modules to accommodate diverse groups of learners and learning styles. In addition, we have completed and scheduled several professional development opportunities on the local and national levels for college and university faculty and secondary teachers and have created a new education and outreach website. Our education programs are being assessed by an external evaluator. We will present interview and focus group results, report on the status of our education programs, and discuss upcoming UNAVCO education activities.

  16. Inelastic models of lithospheric stress - I. Theory and application to outer-rise plate deformation

    Science.gov (United States)

    Mueller, S.; Choy, G.L.; Spence, W.

    1996-01-01

    Outer-rise stress distributions determined in the manner that mechanical engineers evaluate inelastic stress distributions within conventional materials are contrasted with those predicted using simple elastic-plate models that are frequently encountered in studies of outer-rise seismicity. This comparison indicates that the latter are inherently inappropriate for studies of intraplate earthquakes, which are a direct manifestation of lithospheric inelasticity. We demonstrate that the common practice of truncating elastically superimposed stress profiles so that they are not permitted to exceed laboratory-based estimates of lithospheric yield strength will result in an accurate characterization of lithospheric stress only under relatively restrictive circumstances. In contrast to elastic-plate models, which predict that lithospheric stress distributions depend exclusively upon the current load, inelastic plate models predict that stress distributions are also significantly influenced by the plate-loading history, and, in many cases, this influence is the dominant factor in determining the style of potential seismicity (e.g. thrust versus normal faulting). Numerous 'intuitive' interpretations of outer-rise earthquakes have been founded upon the implicit assumption that a unique relationship exists between a specified combination of plate curvature and in-plane force, and the resulting lithospheric stress distribution. We demonstrate that the profound influence of deformation history often invalidates such interpretations. Finally, we examine the reliability of 'yield envelope' representations of lithospheric strength that are constructed on the basis of empirically determined frictional sliding relationships and silicate plastic-flow laws. Although representations of this nature underestimate the strength of some major interplate faults, such as the San Andreas, they appear to represent a reliable characterization of the strength of intraplate oceanic lithosphere.

  17. Tectonic plate under a localized boundary stress: fitting of a zero-range solvable model

    CERN Document Server

    Petrova, L

    2008-01-01

    We suggest a method of fitting of a zero-range model of a tectonic plate under a boundary stress on the basis of comparison of the theoretical formulae for the corresponding eigenfunctions/eigenvalues with the results extraction under monitoring, in the remote zone, of non-random (regular) oscillations of the Earth with periods 0.2-6 hours, on the background seismic process, in case of low seismic activity. Observations of changes of the characteristics of the oscillations (frequency, amplitude and polarization) in course of time, together with the theoretical analysis of the fitted model, would enable us to localize the stressed zone on the boundary of the plate and estimate the risk of a powerful earthquake at the zone.

  18. World Stress Map Release 2005 - Stress orientations from single focal mechanisms at plate boundaries

    Science.gov (United States)

    Heidbach, O.; Barth, A.; Müller, B.; Reinecker, J.; Sperner, B.; Tingay, M.

    2005-12-01

    The World Stress Map (WSM) is a global compilation of data about recent tectonic stresses from a wide range of indicators (e.g. focal mechanisms, borehole breakouts). It is a valuable tool for the solution of numerous of technological and scientific problems. The orientation of the stress field, for instance, is a primary control on subsurface fluid flow and thus WSM data can be used to improve petroleum production or the efficiency of geothermal power stations. In scientific context, information on the stress state is essential for seismic hazard assessment. The WSM database release 2005 contains more than 14,000 data sets all classified according to a unified quality ranking. Thus, the comparability of data from different types of measurement is guaranteed. The database as well as guidelines and software for plotting stress maps are available free of charge from our website www.world-stress-map.org. Users can create their own stress map including their own stress data almost instantly with the CASMO (Create A Stress Map Online) web tool. Alternatively, users can download the software CASMI (Create A Stress Map Interactively) free of charge and produce their own stress maps. In the WSM 2005 release we refined the definition of so-called Possible Plate Boundary Events (PBE) for stress data from single focal mechanisms (FMS) considering that the orientations of these earthquakes might be rather controlled by the geometry of the plate boundary than by the stress field orientation. In general, it is assumed that numerous randomly oriented faults are present in the crust, so that earthquakes occur on faults optimally oriented relative to the regional stress field. In such a setting the principal axes of the moment tensor (P, B, T) provide good approximations for the principal stress orientations (σ_1, σ2, σ3). However, plate boundaries show a different mechanical behavior. They are characterized by faults with preferred orientations and presumably include major

  19. Near Continuum Velocity and Temperature Coupled Compressible Boundary Layer Flow over a Flat Plate

    Science.gov (United States)

    He, Xin; Cai, Chunpei

    2017-04-01

    The problem of a compressible gas flows over a flat plate with the velocity-slip and temperature-jump boundary conditions are being studied. The standard single- shooting method is applied to obtain the exact solutions for velocity and temperature profiles when the momentum and energy equations are weakly coupled. A double-shooting method is applied if these two equations are closely coupled. If the temperature affects the velocity directly, more significant velocity slip happens at locations closer to the plate's leading edge, and inflections on the velocity profiles appear, indicating flows may become unstable. As a consequence, the temperature-jump and velocity-slip boundary conditions may trigger earlier flow transitions from a laminar to a turbulent flow state.

  20. MHD Natural Convection with Convective Surface Boundary Condition over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad M. Rashidi

    2014-01-01

    Full Text Available We apply the one parameter continuous group method to investigate similarity solutions of magnetohydrodynamic (MHD heat and mass transfer flow of a steady viscous incompressible fluid over a flat plate. By using the one parameter group method, similarity transformations and corresponding similarity representations are presented. A convective boundary condition is applied instead of the usual boundary conditions of constant surface temperature or constant heat flux. In addition it is assumed that viscosity, thermal conductivity, and concentration diffusivity vary linearly. Our study indicates that a similarity solution is possible if the convective heat transfer related to the hot fluid on the lower surface of the plate is directly proportional to (x--1/2 where x- is the distance from the leading edge of the solid surface. Numerical solutions of the ordinary differential equations are obtained by the Keller Box method for different values of the controlling parameters associated with the problem.

  1. Control of boundary layer transition location and plate vibration in the presence of an external acoustic field

    Science.gov (United States)

    Maestrello, L.; Grosveld, F. W.

    1991-01-01

    The experiment is aimed at controlling the boundary layer transition location and the plate vibration when excited by a flow and an upstream sound source. Sound has been found to affect the flow at the leading edge and the response of a flexible plate in a boundary layer. Because the sound induces early transition, the panel vibration is acoustically coupled to the turbulent boundary layer by the upstream radiation. Localized surface heating at the leading edge delays the transition location downstream of the flexible plate. The response of the plate excited by a turbulent boundary layer (without sound) shows that the plate is forced to vibrate at different frequencies and with different amplitudes as the flow velocity changes indicating that the plate is driven by the convective waves of the boundary layer. The acoustic disturbances induced by the upstream sound dominate the response of the plate when the boundary layer is either turbulent or laminar. Active vibration control was used to reduce the sound induced displacement amplitude of the plate.

  2. Unsteady Boundary-Layer Flow over Jerked Plate Moving in a Free Stream of Viscoelastic Fluid

    Directory of Open Access Journals (Sweden)

    Sufian Munawar

    2014-01-01

    Full Text Available This study aims to investigate the unsteady boundary-layer flow of a viscoelastic non-Newtonian fluid over a flat surface. The plate is suddenly jerked to move with uniform velocity in a uniform stream of non-Newtonian fluid. Purely analytic solution to governing nonlinear equation is obtained. The solution is highly accurate and valid for all values of the dimensionless time 0≤τ<∞. Flow properties of the viscoelastic fluid are discussed through graphs.

  3. Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary

    OpenAIRE

    Silva, H. G; Bezzeghoud, M.; J. P. Rocha; P. F. Biagi; Tlemçani, M.; Rosa, R.N.; M. A. Salgueiro da Silva; Borges, J. F.; Caldeira, B.; Reis, A. H.; MANSO M.

    2011-01-01

    This paper presents a future research plan that aims to monitor Seismo-electromagnetic (SEM) phenomena in the western part of the Eurasia-Nubia plate boundary (WENP). This region has a significant tectonic activity [1] combined with relatively low electromagnetic noise levels and for that reason presents the possibility to perform high quality SEM measurements. Further, it is known that low-frequency [ultra (ULF), very (VLF), and low-frequencies (LF)] electromag- netic (EM) waves produce m...

  4. Spectral simulation of thermocapillary convection with a deformable free surface using boundary-fitted coordinates

    Science.gov (United States)

    Ahmed, Ikramuddin

    A Chebyshev-spectral collocation scheme has been developed to simulate thermocapillary convection processes in a differentially heated cavity with and without buoyancy effects. The time-dependent Navier- Stokes equations in primitive variables were solved with a semi-implicit scheme using the influence matrix technique. The deformable free surface was incorporated by means of a boundary-fitted coordinate (BFC) system. The BFC grid was generated by solving a system of elliptic equations. An iterative scheme based on finite difference methods was found to be sufficient for calculating a smooth distribution of grid-points for relatively low degrees of deformation of the free surface. The metrics of transformation, however, were calculated spectrally in order to achieve a high order of accuracy in the a posteriori mapping of the physical grid to the computational grid. The overall scheme was found to be efficient, economical, and capable of resolving the complex hydrodynamic and thermal structures in thermocapillarity driven flows with deformable free surfaces. The scheme was also modified to study problems with very high Marangoni numbers and non-deformable free surfaces, and later extended to three dimensions with periodic boundary conditions in order to explore the transitions to fully three dimensional phenomena that are anticipated in industrially relevant flow configurations.

  5. Experimental Study of the Effect of Disorientation Angle on the Deformation of Carbon Composite Plates

    Directory of Open Access Journals (Sweden)

    Olga BITKINA

    2016-05-01

    Full Text Available The disorientation angle, a technological error in the manufacture of carbon composite materials, is the most important determinant of deviation of the obtained surface shape from the planned shape. Elimination of these defects results in additional time and financial costs. Therefore, this study examined the influence of the disorientation angle experimentally using carbon plastic (KMU-4l composite plates measuring 300 × 300 mm with different basic structures such as 0/45/-45/90/90/-45/45/0; 0/0/60/-60/-60/60/0/0; 0/30/-30/90/90/-30/30/0. Plates were manufactured at a curing temperature of 175 °C and cooled to room temperature (23 °C. Fibers were pre-tensioned; the tension was removed after curing. The difference between the curing temperature and room temperature caused thermal stress and deformation in the material structure. This was examined together with the effect of the disorientation angle. Experimental results for composite plate hogging as a function of the disorientation angle and thermal load were analyzed for different structures.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12932

  6. A Novel Higher-Order Shear and Normal Deformable Plate Theory for the Static, Free Vibration and Buckling Analysis of Functionally Graded Plates

    Directory of Open Access Journals (Sweden)

    Shi-Chao Yi

    2017-01-01

    Full Text Available Closed-form solution of a special higher-order shear and normal deformable plate theory is presented for the static situations, natural frequencies, and buckling responses of simple supported functionally graded materials plates (FGMs. Distinguished from the usual theories, the uniqueness is the differentia of the new plate theory. Each individual FGM plate has special characteristics, such as material properties and length-thickness ratio. These distinctive attributes determine a set of orthogonal polynomials, and then the polynomials can form an exclusive plate theory. Thus, the novel plate theory has two merits: one is the orthogonality, where the majority of the coefficients of the equations derived from Hamilton’s principle are zero; the other is the flexibility, where the order of the plate theory can be arbitrarily set. Numerical examples with different shapes of plates are presented and the achieved results are compared with the reference solutions available in the literature. Several aspects of the model involving relevant parameters, length-to-thickness, stiffness ratios, and so forth affected by static and dynamic situations are elaborate analyzed in detail. As a consequence, the applicability and the effectiveness of the present method for accurately computing deflection, stresses, natural frequencies, and buckling response of various FGM plates are demonstrated.

  7. Gramicidin channel-induced lipid membrane deformation energy: influence of chain length and boundary conditions.

    Science.gov (United States)

    Ring, A

    1996-01-31

    The influence of boundary conditions on the deformation energy of a lipid membrane containing a gramicidin A channel was evaluated numerically. A liquid crystal model was used to calculate the relative contributions of compression, splay and surface tension. It is proposed that the nearest neighbor lipid molecules are displaced from the channel end in a direction perpendicular to the bilayer and it is concluded that surface tension is the major component of the deformation free energy for monoolein (gmo)/n-alkane membranes. This unexpected result supports the validity of the liquid crystal models of membrane deformation since gramicidin lifetime has been shown to correlate with surface tension for gmo membranes. The theory accurately predicts the experimentally measured relative lifetimes without the use of adjustable parameters. For conditions where splay may be neglected surface tension is always the major component of the deformation energy, irrespective of the magnitude of the compression coefficient. The deformation may extend for hundreds of angstroms from the peptide. The results obtained here are expected to be important for the characterization of protein-membrane interactions in general.

  8. Streamwise counter-rotating vortices generated by triangular leading edge pattern in flat plate boundary layer

    KAUST Repository

    Hasheminejad, S. M.

    2016-01-05

    A series of flow visualizations were conducted to qualitatively study the development of streamwise counter-rotating vortices over a flat plate induced by triangular patterns at the leading edge of a flat plate. The experiments were carried out for a Reynolds number based on the pattern wavelength (λ) of 3080. The results depict the onset, development and breakdown of the vortical structures within the flat plate boundary layer. Moreover, the effect of one spanwise array of holes with diameter of 0.2λ (=3 mm) was examined. This investigation was done on two different flat plates with holes placed at the location x/λ = 2 downstream of the troughs and peaks. The presence of holes after troughs does not show any significant effect on the vortical structures. However, the plate with holes after peaks noticeably delays the vortex breakdown. In this case, the “mushroom-like” vortices move away from the wall and propagate downstream with stable vortical structures. The vortex growth is halted further downstream but start to tilt aside.

  9. Deformations between African and Euroasian plates estimated by methods of space geodesy - new result

    Science.gov (United States)

    Zeman, A.; Holesovsky, J.; Novotny, Z.; Hassan, K. A.; Abd El Monem, M. S.; Kostelecky, J.

    2009-12-01

    The contribution concerns with analysis of detailed information from the results of space geodesy (GPS) in the region of Mediterranean sea enclosing the results of till now not processed and published observations in quasipermanent network of the sites in Egypt. (It was made possible by agreement between the National Research Institute of Astronomy and Geophysics in Egypt and the Research Center of Earth Dynamics in Czech Republic). A main topic in WEGENER's project activities is observation of geodynamic processes of the European-Mediterranean region, northern Africa and Asia Minor, by (space) geodetic techniques. The geodynamic setting of the region is formed by the convergence of the three major lithosphere plates (Eurasia, Africa and Arabia). In the plate boundary zones a variety of subduction and collision processes are active. The cotribution contains actual results of processing of the observations in Egypt together with selected sites of permanent EPN network in region of eastern part of Mediterranean sea. Results of analyses confirm model presumption of mutual activities between African, Arabic and Euroasian plates.

  10. The boundary between the Indian and Asian tectonic plates below Tibet.

    Science.gov (United States)

    Zhao, Junmeng; Yuan, Xiaohui; Liu, Hongbing; Kumar, Prakash; Pei, Shunping; Kind, Rainer; Zhang, Zhongjie; Teng, Jiwen; Ding, Lin; Gao, Xing; Xu, Qiang; Wang, Wei

    2010-06-22

    The fate of the colliding Indian and Asian tectonic plates below the Tibetan high plateau may be visualized by, in addition to seismic tomography, mapping the deep seismic discontinuities, like the crust-mantle boundary (Moho), the lithosphere-asthenosphere boundary (LAB), or the discontinuities at 410 and 660 km depth. We herein present observations of seismic discontinuities with the P and S receiver function techniques beneath central and western Tibet along two new profiles and discuss the results in connection with results from earlier profiles, which did observe the LAB. The LAB of the Indian and Asian plates is well-imaged by several profiles and suggests a changing mode of India-Asia collision in the east-west direction. From eastern Himalayan syntaxis to the western edge of the Tarim Basin, the Indian lithosphere is underthrusting Tibet at an increasingly shallower angle and reaching progressively further to the north. A particular lithospheric region was formed in northern and eastern Tibet as a crush zone between the two colliding plates, the existence of which is marked by high temperature, low mantle seismic wavespeed (correlating with late arriving signals from the 410 discontinuity), poor Sn propagation, east and southeast oriented global positioning system displacements, and strikingly larger seismic (SKS) anisotropy.

  11. An immersed-boundary method for modeling flow of deformable blood cells in complex geometry

    Science.gov (United States)

    Balogh, Peter; Bagchi, Prosenjit

    2016-11-01

    We present a computational methodology for simulating blood flow at the cellular scale in highly complex geometries, such as microvascular networks. Immersed boundary methods provide the foundation for our approach, as they allow modeling flows in arbitrary geometries, in addition to resolving the large deformation and dynamics of individual blood cell with high fidelity. Different simulation components are seamlessly integrated into the present methodology that can simultaneously model stationary rigid boundaries of arbitrary and complex shape, moving rigid bodies, and highly deformable interfaces of blood cells that are governed by non-linear elasticity. This permits physiologically realistic simulations of blood cells flowing in complex microvascular networks characterized by multiple bifurcating and merging vessels. The methodology is validated against analytical theory, experimental data, and previous numerical results. We then demonstrate the capabilities of the methodology by simulating deformable blood cells and heterogeneous cell suspensions flowing in both physiologically realistic microvascular networks and geometrically intricate microfluidic devices. The methodology offers the potential of scaling up to large microvascular networks at organ levels. Funded by NSF CBET 1604308.

  12. Seismicity and seismotectonics of the diffusive Iberian/African plate boundary: Horseshoe Abyssal Plain and Gorringe Bank

    Science.gov (United States)

    Grevemeyer, Ingo; Lange, Dietrich; Matias, Luis

    2014-05-01

    In the area to the west of the Gibraltar Arc the plate boundary between Africa and Iberia is poorly defined. The deformation in the area is forced by the slow NW-SE convergence of 4 mm/yr between the oceanic domains of Iberia/Eurasia and Africa and is accommodated over a 200 km broad tectonically-active deformation zone. The region, however, is also characterized by large earthquakes and tsunamis, such as the 1969 Mw=7.9 Horseshoe Abyssal Plain earthquake and the November 1, 1755 Great Lisbon earthquake with an estimated magnitude of Mw~8.5. The exact location of the source of the 1755 Lisbon earthquake is still unknown. Recent work may suggest that the event occurred in the vicinity of the Horseshoe fault, an oblique thrust fault. However, estimates of tsunami arrival times suggested a source near the Gorringe Bank, a ~180 km-long and ~70 km-wide ridge that has a relieve of ~5000 m. Deep Sea Drilling (DSDP) and rock samples indicated that the bank is mainly composed of serpentinized peridotites with gabbroic intrusions, perhaps being created by overthrusting of the Horseshoe Abyssal Plain onto the Tagus Abyssal Plain in NW direction. Further, the Horseshoe Abyssal Plain is marked by the presence of compressive structures with a roughly NE-SW orientation and E-W trending, segmented, crustal-scale, strike slip faults that extend from the Gorringe Bank to the Gibraltar Arc in the eastern Gulf of Cadiz, which were called "South West Iberian Margin" or SWIM faults. The fault system may mark a developing Eurasia-Africa plate boundary. Two local seismic networks were operated in the area. First, a network of 14 ocean-bottom seismometers (OBS) was operated between April and October 2012 in the vicinity of the Horseshoe fault between 10°W to 11°W, and 35°50'N to 36°10'N. From October 2013 to March 2014 a second network of 15 OBS monitored seismicity at the Gorringe Bank. Both networks benefitted from seismic stations operated in Portugal. The first network provided in

  13. Seismicity of the diffusive Iberian/African plate boundary at the eastern terminus of the Azores-Gibraltar Transform fault

    Science.gov (United States)

    Lange, D.; Grevemeyer, I.; Matias, L. M.

    2014-12-01

    The plate boundary at the eastern terminus of the Azores-Gibraltar transform fault between Africa and Iberia is poorly defined. The deformation in the area is forced by the slow NW-SE convergence of 4 mm/yr between the oceanic domains of Iberia/Eurasia and Africa and is accommodated over a 200 km broad tectonically-active deformation zone. The region, however, is also characterized by large earthquakes, such as the 1969 Mw=7.9 Horseshoe event and the November 1, 1755 Great Lisbon earthquake with an estimated magnitude of Mw~8.5. The exact location of the source of the 1755 Lisbon earthquake is still unknown. Recent work may suggest that the event occurred in the vicinity of the Horseshoe fault, an oblique thrust fault. However, estimates of tsunami arrival times suggested a source near the Gorringe Bank, a ~180 km-long and ~70 km-wide ridge that has a relieve of ~5000 m. Deep Sea Drilling (DSDP) and rock samples indicated that the bank is mainly composed of serpentinized peridotites with gabbroic intrusions, perhaps being created by overthrusting of the Horseshoe Abyssal Plain onto the Tagus Abyssal Plain in NW direction. Further, the Horseshoe Abyssal Plain is marked by the presence of compressive structures with a roughly NE-SW orientation and E-W trending, segmented, crustal-scale, strike slip faults that extend from the Gorringe Bank to the Gibraltar Arc in the eastern Gulf of Cadiz, which were called "South West Iberian Margin" or SWIM faults. The fault system may mark a developing Eurasia-Africa plate boundary. Two local seismic networks were operated in the area. First, a network of 14 ocean-bottom seismometers (OBS) was operated between April and October 2012 in the vicinity of the Horseshoe fault between 10°W to 11°W, and 35°50'N to 36°10'N. From October 2013 to March 2014 a second network of 15 OBS monitored seismicity at the Gorringe Bank. Both networks benefitted from seismic stations operated in Portugal. The first network provided in the order of

  14. Prediction of Velocity and Deformation Fields During Multipass Plate Hot Rolling by Novel Mixed Analytical-Numerical Met%Prediction of Velocity and Deformation Fields During Multipass Plate Hot Rolling by Novel Mixed Analytical-Numerical Me

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jin-ling; CUI Zhen-shan

    2011-01-01

    An integrated mathematical model is proposed to predict the velocity field and strain distribution during multi-pass plate hot rolling. This model is a part of the mixed analytical-numerical method (ANM) aiming at predic- tion of deformation variables, te

  15. Relationship between boundary misorientation angle and true strain during high temperature deformation of 7050 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    HU Hui-e; YANG Li; ZHEN Liang; SHAO Wen-zhu; ZHANG Bao-you

    2008-01-01

    Tensile tests of solid solution treated 7050 aluminum alloy were conducted to different strain degrees (0.1, 0.4, 0.6 and failure) at 460 ℃ with the strain rate of 1.0×10-4-1.0×10-1s-1. The boundary misorientation angle evolution during hot deformation of the 7050 aluminum alloy was studied by EBSD technique and the fracture surfaces were observed using SEM. A linear relationship between the increase in the average boundary misorientation angle and the true strain at different strain rates is assumed when aluminum alloy is deformed at 460 ℃. The increasing rate of average boundary misorientation angle is 15.1-, 15.7- and -0.75- corresponding to the strain rate of 1.0×10-4, 1.0×10-2 and 0.1 s-1, respectively. The main softening mechanism is continuous dynamic recrystallization when the strain rates are 1.0×10-4 and 1.0×10-2 s-1, and it is dynamic recovery when strain rate is 0.1 s-1.

  16. Phase boundary sliding model controlled by diffusion-solution zone in superplastic deformation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With scanning electron microscope (SEM), the surface morphology of phase boundary sliding (PBS) in superplastic deformation (SPD) of Zn-Al alloy and the diffusion behavior of Zn, Al interfaces in their powers' sintering have been investigated. The results show that Zn-Al eutectoid microstructure can be achieved through their powders' sintering, and the diffusion characteristic between Zn and Al is just a demonstration of Kirkendall effect, in which Zn can dissolve into Al whereas A1 can hardly dissolve into Zn. During sintering, a diffusion-solution zone ?′ has formed and subsequently transformed into a eutectoid microstructure in the cooling process. The superplastic deformation mechanism of Zn-Al eutectic alloy is phase boundary sliding which is controlled by the diffusion-solution zone ?′. If the diffusion-solution zone ?′ is unsaturated, it will have much more crystal defects and the combination between ?′ and phase ? is weak, thus the process of phase boundary sliding becomes easily; on the contrary, if the diffusion-solution zone ?′ becomes thick and saturated, the sliding will be difficult.

  17. A comparison of hydrological deformation using GPS and global hydrological model for the Eurasian plate

    Science.gov (United States)

    Li, Zhen; Yue, Jianping; Li, Wang; Lu, Dekai; Li, Xiaogen

    2017-08-01

    The 0.5° × 0.5° gridded hydrological loading from Global Land Surface Discharge Model (LSDM) mass distributions is adopted for 32 GPS sites on the Eurasian plate from January 2010 to January 2014. When the heights of these sites that have been corrected for the effects of non-tidal atmospheric and ocean loading are adjusted by the hydrological loading deformation, more than one third of the root-mean-square (RMS) values of the GPS height variability become larger. After analyzing the results by continuous wavelet transform (CWT) and wavelet transform coherence (WTC), we confirm that hydrological loading primarily contributes to the annual variations in GPS heights. Further, the cross wavelet transform (XWT) is used to investigate the relative phase between the time series of GPS heights and hydrological deformation, and it is indicated that the annual oscillations in the two time series are physically related for some sites; other geophysical effect, GPS systematic errors and hydrological modeling errors could result in the phase asynchrony between GPS and hydrological loading signals for the other sites. Consequently, the phase asynchrony confirms that the annual fluctuations in GPS observations result from a combination of geophysical signals and systematic errors.

  18. Flat plate heat transfer for laminar transition and turbulent boundary layers using a shock tube

    Science.gov (United States)

    Brostmeyer, J. D.; Nagamatsu, H. T.

    1984-01-01

    Heat transfer results are presented for laminar, transition, and turbulent boundary layers for a Mach number of 0.12 with gas temperatures of 425 K and 1000 K over a flat plate at room temperature. The measurements were made in air for a Reynolds number range of 600 to 6 million. The heat transfer measurements were conducted in a 70-ft long, 4 in. diameter shock tube. Reflecting wedges were used to reflect the incident shock wave to produce a flow Mach number of 0.12 behind the reflected shock wave. Thin film platinum heat gages were mounted on the plate surface to measure the local heat flux. The laminar results for gas temperatures of 425 K to 1000 K agree well with theory. The turbulent results are also close to incompressible theory, with the 1000 K flow case being slightly higher. The transition results lie between the laminar and turbulent predictions.

  19. Active faulting and transpression tectonics along the plate boundary in North Africa

    Directory of Open Access Journals (Sweden)

    Mustapha Meghraoui

    2013-01-01

    Full Text Available We present a synthesis of the active tectonics of the northern Atlas Mountains, and suggest a kinematic model of transpression and block rotation that illustrates the mechanics of this section of the Africa–Eurasia plate boundary. Neotectonic structures and significant shallow seismicity (with Mw >5.0 indicate that coeval E-W-trending, right-lateral faulting and NE-SW, thrust-related folding result from oblique convergence at the plate boundary, which forms a transpressional system. The strain distribution obtained from fault–fold structures and P axes of focal mechanism solutions, and the geodetic (NUVEL-1 and GPS convergence show that the shortening and convergence directions are not coaxial. The transpressional strain is partitioned along the strike and the quantitative description of the displacement field yields a compression-to-transcurrence ratio varying from 33% near Gibraltar, to 50% along the Tunisian Atlas. Shortening directions oriented NNE and NNW for the Pliocene and Quaternary, respectively, and the S shape of the Quaternary anticline axes, are in agreement with the 2.24˚/Myr to 3.9˚/Myr modeled clockwise rotation of the small tectonic blocks and with the paleomagnetic data. The convergence between Africa and Eurasia is absorbed along the Atlas Mountains at the upper crustal level, by means of thrusting above decollement systems, which are controlled by subdued transcurrent faults. The Tell Atlas of northwest Algeria, which has experienced numerous large earthquakes with respect to the other regions, is interpreted as a restraining bend that localizes the strain distribution along the plate boundary.

  20. The boundary point method for Reissner′s plates%Reissner型板边界点法

    Institute of Scientific and Technical Information of China (English)

    吴约; 王左辉

    2001-01-01

    In this paper, a series of particular solutions are formed by utilizing correspondent Reissher′s plate fundamental solutions. Thus all elements in the coefficient matrix of boundary element equations for plates to be solved will be determined by boundary point method. In the process of solving, interpolation and numerical integration are not needed and numerical treatment for singular integration is avoided, meanwhile, the calculation of physical characteristics of any point does not depend on boundary unknowns to be solved, therefore, the accuracy is excellent. The method presented may be applied to solving the problems of all kinds of plates and shells no matter if the problem is isotropic or anisotropic. But it should be noticed that the matrix of all particular solution field should conform with the fundamental solution of the specific problem.%文章采用Reissner型板基本解来构建一系列特解,再通过边界点法确定边界元方程系效矩阵的全部元素。解算中不涉及具体插值,不用数值积分,避免了奇性处理,而任意点物理量的计算不依赖于待解的边界未知量,算效高,精度好。该法还可用来分析其它各类板壳问题,无论是各向同性还是各向异性的,不同的只是应按各自的基本解来构造全特解场矩阵。

  1. Inherited segmentation of the Iberian-African margins and tectonic reconstruction of a diffuse plate boundary.

    Science.gov (United States)

    Fernàndez, Manel; Torne, Montserrat; Vergés, Jaume; Casciello, Emilio

    2016-04-01

    Diffuse plate-boundary regions are characterized by non-well defined contacts between tectonic plates thus making difficult their reconstruction through time. The Western Mediterranean is one of these regions, where the convergence between the African and Iberian plates since Late Cretaceous resulted in the Betic-Rif arcuate orogen, the Gulf of Cadiz imbricate wedge, and the Alboran back-arc basin. Whereas the Iberia-Africa plate boundary is well defined west to the Gorringe Bank and along the Gloria Fault, it becomes much more diffuse eastwards with seismicity spreading over both the south-Iberian and north-African margins. Gravity data, when filtered for short wavelengths, show conspicuous positive Bouguer anomalies associated with the Gorringe Bank, the Gulf of Cadiz High and the Ronda/Beni-Bousera peridotitic massifs reflecting an inherited Jurassic margin segmentation. The subsequent Alpine convergence between Africa and Iberia reactivated these domains, producing crustal-scale thrusting in the Atlantic segments and eventually subduction in the proto-Mediterranean segments. The Jurassic segmentation of the Iberia-Africa margins substantiates the double-polarity subduction model proposed for the region characterized by a change from SE-dipping polarity in the Gorringe, Gulf of Cadiz and Betic-Rif domains, to NW-dipping polarity in the proto-Algerian domain. Therefore, the Algerian and Tyrrhenian basins in the east and the Alboran basin in the west are the result of SSE-E and NW-W retreating slabs of oceanic and/or hyper-extended Tethyan domains, respectively.

  2. Triangular Differential Quadrature for Bending Analysis of Reissner Plates with Curved Boundaries

    Institute of Scientific and Technical Information of China (English)

    华永霞; 钟宏志

    2003-01-01

    The recently proposed concept of the triangular differential quadrature method (TDQM) is applied to the bending analysis of Reissner plates with various curvilinear geometries subjected to various combinations of boundary conditions. A unit isosceles right triangle is used as the standard triangle for all the derivatives expressed using the triangular differential quadrature rule. Geometric transformations are introduced using basis functions to determine the weighting coefficients for the triangular differential quadrature to map an arbitrary curvilinear triangle into the standard triangle. The triangular differential quadrature method provides good accuracy and rapid convergence relative to other available exact and numerical results.

  3. Stability and coherent structures of the asymptotic suction boundary layer over a heated plate

    CERN Document Server

    Zammert, Stefan; Eckhardt, Bruno

    2016-01-01

    The asymptotic suction boundary layer (ASBL) is a parallel shear flow that becomes turbulent in a bypass transition in parameter regions where the laminar profile is stable. We here add a temperature gradient perpendicular to the plate and explore the interaction between convection and shear in determining the transition. We find that the laminar state becomes unstable in a subcritical bifurcation and that the critical Rayleigh number and wave number depend strongly on the Prandtl number. We also track several secondary bifurcations and identify states that are localized in two directions, showing different symmetries. In the subcritical regime, transient turbulent states which are connected to exact coherent states and follow the same transition scenario as found in linearly stable shear flows are identified and analyzed. The study extends the bypass transition scenario from shear flows to thermal boundary layers and shows the intricate interactions between thermal and shear forces in determining critical po...

  4. Boundary Layer Flow and Heat Transfer of FMWCNT/Water Nanofluids over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Safaei

    2016-09-01

    Full Text Available In the present study, the heat transfer and flow of water/FMWCNT (functionalized multi-walled carbon nanotube nanofluids over a flat plate was investigated using a finite volume method. Simulations were performed for velocity ranging from 0.17 mm/s to 1.7 mm/s under laminar regime and nanotube concentrations up to 0.2%. The 2-D governing equations were solved using an in-house FORTRAN code. For a specific free stream velocity, the presented results showed that increasing the weight percentage of nanotubes increased the Nusselt number. However, an increase in the solid weight percentage had a negligible effect on the wall shear stress. The results also indicated that increasing the free stream velocity for all cases leads to thinner boundary layer thickness, while increasing the FMWCNT concentration causes an increase in the boundary layer thickness.

  5. Coherent Structures in Transition of a Flat-Plate Boundary Layer at Ma=0.7

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ying; LI Xin-Liang; FU De-Xun; MA Yan-Wen

    2007-01-01

    @@ Direct numerical simulation (DNS) of a spatially evolving flat-plate boundary layer transition process at free stream Mach number 0.7 is performed. Tollmien-Schlichting (T-S) waves are added on the inlet boundary as the disturbances before transition. Typical coherent structures in the transition process are investigated based on the second invariant of velocity gradient tensor. The instantaneous shear stress and the mean velocity profile in the transition region are studied. In our view, the fact that the peak value of shear stress in the stress concentration area increases and exceeds a threshold value during the later stage of the transition process plays an important role in the laminar breakdown process.

  6. Fluid-mechanical Representation of Plate Boundaries - Trench-Ridge System -

    Science.gov (United States)

    Takaku, M.; Fukao, Y.

    2005-12-01

    Seismic tomography models have been used extensively to simulate mantle convection driven by density heterogeneity. Such simulation to date has been unsuccessful to reconcile itself with the most obvious convection-related phenomenon of plate motions. Here we present a theoretical framework for tomography-based convection modeling to include the plates as an integral part of the mantle convection. We model the lithosphere as a highly viscous, incompressible, Newtonian fluid layer and plate boundaries as faults across which tangential velocities are discontinuous. Fluid-mechanical expressions of such faults have their exact analogies in the seismic source representation theory and can be derived by referring to it. We test this idea against the simplest two-dimensional case with only trench and ridge as plate boundaries, and with only subducting slab as mass anomaly. We model ridge (trench) as the horizontal (vertical) tensile fault that comprises of a conjugate pair of 45-degree dip normal (reverse) faults extending over the entire thickness of the surface layer. The system comprises of three elementary convections, slab mass-driven convection, trench fault-driven convection and ridge fault-driven convection. Flow due to the slab excess mass imposes vertical tensile stress on trench, which is released by flow driven by trench faulting. This faulting converts efficiently the vertical tensile stress to the horizontal tensile stress, which can transmit to extreme distances through the surface viscous layer. This horizontal tensile stress is relieved by flow driven by ridge faulting. The three elementary convections are thus coupled through the stress minimum conditions at ridge and trench. The resultant coupled flow is very plate-like in the surface viscous layer. In this system the horizontal surface velocity depends little on the relative distance between the ridge and trench and depends mostly on the excess weight of the subducting slab. The horizontal speed can be

  7. External kinks in plasmas with helical boundary deformation and net toroidal current

    Energy Technology Data Exchange (ETDEWEB)

    Ardelea, A. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1997-11-01

    The investigation of the global ideal magnetohydrodynamic (MHD) stability of plasmas with helical boundary shape and nonvanishing toroidal plasma current constitutes the principal aim of this work. Global external modes with small values of m,n (typically n = 1,2,3 and m = n+1) are studied, where m and n are the poloidal and toroidal mode numbers, respectively. The first and main part of the work concentrates on fixed boundary equilibria generated by systematically varying parameters such as the type and the magnitude of the boundary deformation, the number of equilibrium field periods N{sub per}, the aspect ratio, the toroidal current density profile, {beta} and the pressure profile. Due to the periodicity of the equilibrium, couplings between Fourier perturbation components with different toroidal mode numbers n occur and lead to the apparition of families of modes. The study of a particular (m,n) mode has to take into account all (m{sub l}, n{sub l}) perturbation components with n{sub 1} belonging to the same family as n. The stability analysis is carried out in the parameter region where the inverse rotational transform (the safety factor in the traditional tokamak notation) q{<=}2.0 and {beta}{<=}2%. A particular property of the configurations investigated is that equilibrium Fourier components (m{sub e}, N{sub per}n{sub e}) which are involved in the couplings between the (m,n) mode studied and the (m{sub k},n{sub k}) perturbation components with m{sub k}>n{sub k}>n that exhibit resonances in the q>1 region are very small. As a consequence, the contributions of the (m,n)x(m{sub k},n{sub k}) couplings to the potential energy are very weak. It is shown that a helical boundary deformation can stabilize the n=1,2,3 external modes; if {delta} is a measure of the plasma boundary deformation, then windows of stability [{delta}{sub min}, {delta}{sub max}] may exist for a large variety of equilibrium parameters. (author) figs., tabs., 44 refs.

  8. Flowfield measurements in a separated and reattached flat plate turbulent boundary layer

    Science.gov (United States)

    Patrick, William P.

    1987-03-01

    The separation and reattachment of a large-scale, two-dimensional turbulent boundary layer at low subsonic speed on a flat plate has been studied experimentally. The separation bubble was 55 cm long and had a maximum bubble thickness, measured to the height of the mean dividing streamline, of 17 cm, which was twice the thickness of the inlet boundary layer. A combination of laser velocimetry, hot-wire anemometry, pneumatic probing techniques, and flow visualization were used as diagnostics. Principal findings were that an outer inviscid rotational flow was defined which essentially convected over the blockage associated with the inner, viscously dominated bubble recirculation region. A strong backflow region in which the flow moved upstream 100 percent of the time was measured near the test surface over the central 35 percent of the bubble. A laminar backflow boundary layer having pseudo-turbulent characteristics including a log-linear velocity profile was generated under the highly turbulent backflow. Velocity profile shapes in the reversed flow region matched a previously developed universal backflow profile at the upstream edge of the separation region but not in the steady backflow region downstream. A smoke flow visualization movie and hot-film measurements revealed low frequency nonperiodic flapping at reattachment. However, forward flow fraction data at reattachment and mean velocity profiles in the redeveloping boundary layer downstream of reattachment correlated with backward-facing step data when the axial dimension was scaled by the distance from the maximum bubble thickness to reattachment.

  9. RESEARCH ON THE COMPANION SOLUTION FOR A THIN PLATE IN THE MESHLESS LOCAL BOUNDARY INTEGRAL EQUATION METHOD

    Institute of Scientific and Technical Information of China (English)

    龙述尧; 熊渊博

    2004-01-01

    The meshless local boundary integral equation method is a currently developed numerical method, which combines the advantageous features of Galerkin finite element method(GFEM), boundary element method(BEM) and element free Galerkin method(EFGM), and is a truly meshless method possessing wide prospects in engineering applications.The companion solution and all the other formulas required in the meshless local boundary integral equation for a thin plate were presented, in order to make this method apply to solve the thin plate problem.

  10. Deformation by grain boundary sliding and slip creep versus diffusional creep

    Energy Technology Data Exchange (ETDEWEB)

    Ruano, O A; Sherby, O D; Wadsworth, J

    1998-11-04

    A review is presented of the debates between the present authors and other investigators regarding the possible role of diffusional creep in the plastic flow of polycrystalline metals at low stresses. These debates are recorded in eleven papers over the past seventeen years. ln these papers it has been shown that the creep rates of materials in the so-called "diffusional creep region" are almost always higher than those predicted by the diffusional creep theory. Additionally, the predictions of grain size effects and stress exponents from diffusional creep theory are often not found in the experimental data. Finally, denuded zones have been universally considered to be direct evidence for diffusional creep; but, those reported in the literature are shown to be found only under conditions where a high stress exponent is observed. Also, the locations of the denuded zones do not match those predicted. Alternative mechanisms are described in which diffusion-controlled dislocation creep and/or grain boundary sliding are the dominant deformation processes in low-stress creep. It is proposed that denuded zones are formed by stress-directed grain boundary migration with the precipitates dissolving in the moving grain boundaries. The above observations have led us to the conclusion that grain boundary sliding and slip creep are in fact the principal mechanisms for observations of plastic flow in the so-called "diffusional creep regions".

  11. Correction of coronal plane deformities around the knee using a tension band plate in children younger than 10 years.

    Science.gov (United States)

    Kulkarni, Ruta M; Ilyas Rushnaiwala, Faizaan M; Kulkarni, G S; Negandhi, Rajiv; Kulkarni, Milind G; Kulkarni, Sunil G

    2015-01-01

    Guided growth through temporary hemiepiphysiodesis has gained acceptance as the preferred primary treatment in treating pediatric lower limb deformities as it is minimally invasive with a lesser morbidity than the traditional osteotomy. The tension band plate is the most recent development in implants used for temporary hemiepiphysiodesis. Our aim was to determine its safety and efficacy in correcting coronal plane deformities around the knee in children younger than 10 years. A total of 24 children under the age of 10 were operated for coronal plane deformities around the knee with a single extra periosteal tension band plate and two nonlocking screws. All the children had a pathological deformity for which a detailed preoperative work-up was carried out to ascertain the cause of the deformity and rule out physiological ones. The average age at hemiepiphysiodesis was 5 years 3 months (range: 2 years to 9 years 1 month). The plates were inserted for an average of 15.625 months (range: 7 months to 29 months). All the patients showed improvement in the mechanical axis. Two patients showed partial correction. Two cases of screw loosening were observed. In the genu valgum group, the tibiofemoral angle improved from a preoperative mean of 19.89° valgus (range: 10° valgus to 40° valgus) to 5.72° valgus (range: 2° varus to 10° valgus). In patients with genu varum the tibiofemoral angle improved from a mean of 28.27° varus (range: 13° varus to 41° varus) to 1.59° valgus (range: 0-8° valgus). Temporary hemiepiphysiodesis through the application of the tension band plate is an effective method to correct coronal plane deformities around the knee with minimal complications. Its ease and accuracy of insertion has extended the indication of temporary hemiepiphysiodesis to patients younger than 10 years and across a wide variety of diagnosis including pathological physis, which were traditionally out of the purview of guided growth.

  12. Relaminarization of the boundary layer over a flat plate in shock tube experiments

    Science.gov (United States)

    Hinckel, J. N.; Nagamatsu, H. T.

    1986-01-01

    The relaminarization of the boundary layer over a flat plate in the shock tube was investigated by using the partially reflected shock wave technique. The flow Mach number was approximately 0.14, which corresponds to the inleft flow Mach number for the first row of vanes in a gas turbine. The thin film platinum heat gauges were used to measure the heat transfer rate and the Stanton number was calculated from the oscilloscope voltage traces. The Reynolds number was varied by changing the operation pressure of the shock tube and the values varied from 2.3 x 10 to the 4th to 5.3 x 10 to the 5th. For a Reynolds number range of 7 x 10 to the 4th to 3.5 x 10 to the 5th, the relaminarization of the boundary layer was observed. This phenomenon is due to the decay of the turbulence level in the flow as the reflected shock wave moves upstream from the flat plate. As the Reynolds number increased, the relaminarization was delayed and the delay was related to the turbulence generated by the reflected shock wave.

  13. The ultra low frequency electromagnetic radiation observed in the topside ionosphere above boundaries of tectonic plates

    Directory of Open Access Journals (Sweden)

    Michael A. Athanasiou

    2015-01-01

    Full Text Available In this paper we present results of a comparison between ultra low frequency (ULF electromagnetic (EM radiation, recorded by an electric field instrument onboard the satellite detection of electromagnetic emissions transmitted from earthquake regions in the topside ionosphere, and the seismicity of regions with high and low seismic activity. In particular, we evaluated the energy variations of the ULF Ezelectric field component during a period of four years (2006-2009, in order to examine the possible relation of ULF EM radiation with seismogenic regions located in Central America, Indonesia, the Eastern Mediterranean Basin and Greece. As a tool for evaluating the ULF Ez energy variations we used singular spectrum analysis techniques. The results of our analysis clearly show a significant increase of the ULF EM energy emitted from regions of highest seismic activity at the boundaries tectonic plates. Furthermore, we found that higher electromagnetic radiation was detected in a region above the northern- western Greek Arc (R1 than above the adjacent region including Athens and its urban area. We interpret these results of the present study as suggesting that: i the seismogenic regions at the boundary of tectonic plates radiate ULF EM emissions observed by satellites in the topside ionosphere; and ii that this EM radiation is not only related with the occurrence time of great (M≥5 earthquakes, but it is often present in intermediate times and it appears as a quasi-permanent phenomenon.

  14. Effects of displacement boundary conditions on thermal deformation in thermal stress problems

    Directory of Open Access Journals (Sweden)

    S. Y. Kwak

    2013-05-01

    Full Text Available Most computational structural engineers are paying more attention to applying loads rather than to DBCs (Displacement Boundary Conditions because most static stable mechanical structures are working under already prescribed displacement boundary conditions. In all of the computational analysis of solving a system of algebraic equations, such as FEM (Finite Element Method, three translational and three rotational degrees of freedom (DOF should be constrained (by applying DBCs before solving the system of algebraic equation in order to prevent rigid body motions of the analysis results (singular problem. However, it is very difficult for an inexperienced engineer or designer to apply proper DBCs in the case of thermal stress analysis where no prescribed DBCs or constraints exist, for example in water quenching for heat treatment. Moreover, improper DBCs cause incorrect solutions in thermal stress analysis, such as stress concentration or unreasonable deformation phases. To avoid these problems, we studied a technique which performs the thermal stress analysis without any DBCs; and then removes rigid body motions from the deformation results in a post process step as the need arises. The proposed technique makes it easy to apply DBCs and prevent the error caused by improper DBCs. We proved it was mathematically possible to solve a system of algebraic equations without a step of applying DBCs. We also compared the analysis results with those of a traditional procedure for real castings.

  15. Crustal deformation in northern Central America

    Science.gov (United States)

    Cáceres, Diego; Monterroso, David; Tavakoli, Behrooz

    2005-07-01

    Evaluation of the seismic moment tensor for earthquakes on plate boundary is a standard procedure to determine the relative velocity of plates, which controls the seismic deformation rate predicted from the slip on a single fault. The moment tensor is also decomposed into an isotropic and a deviatoric part to discover the relationship between the average strain rate and the relative velocity between two plates. We utilize this procedure to estimate the rates of deformation in northern Central America where plate boundaries are seismically well defined. Four different tectonic environments are considered for modelling of the plate motions. The deformation rates obtained here compare well with those predicted from the plate motions models and are in good agreement with actual observations. Deformation rates on faults are increasingly being used to estimate earthquake recurrence from information on fault slip rate and more on how we can incorporate our current understanding into seismic hazard analyses.

  16. Coefficient of Variation Estimates for the Plate Boundary Fault System of California

    Science.gov (United States)

    Biasi, G. P.; Scharer, K. M.

    2015-12-01

    The number of high-quality paleoseismic records on major strike-slip faults of California has increased in recent years to the point that patterns in earthquake recurrence are emerging. The degree of predictability in time intervals between ground-rupturing earthquakes can be measured by the CoV (coefficient of variation). The CoV approximately normalizes for mean recurrence, and is thus useful to isolate the temporal variability of earthquake records. CoV estimates are themselves uncertain because input dates are actually probability distributions and because paleoseismic records are short and not necessarily representative samples from the underlying recurrence distribution. Radiocarbon dating uncertainty can be incorporated by sampling from event PDFs and compiling sample CoV estimates. Uncertainty due to the brevity of the site event record is larger, and neglect of it can lead to improbable estimates. Long records are now available on the San Andreas and San Jacinto faults in Southern California, and the San Andreas and Hayward faults in northern California. These faults accommodate most of the Pacific-North American relative plate motion in their respective regions. CoV estimates from sites with 8 or more events cluster around 0.63, but are as low as 0.4 for the southern Hayward fault. Sites with fewer events give similar estimates, though with lower resolution. The one prominent outlier, Burro Flats, with a CoV near 1.0, is in a region of severe fault complexity and rapid fault-normal compression. Quasi-periodic recurrence is emerging as a general property for these plate boundary faults. Some individual site records allow that, at low probabilities, recurrence could be random in time. When the ensemble is considered together, however, it is improbable that we would see the observed degree of agreement among boundary fault paleoseismic records; the more likely explanation is that quasi-periodic recurrence is a real property of the boundary fault system.

  17. Finite element analysis of controlling the TC4 thin plate weldment wave-like deformation by welding with impacting rotation

    Institute of Scientific and Technical Information of China (English)

    Zhang Yong; Yang Jianguo; Liu Xuesong; Fang Hongyuan

    2010-01-01

    The new technology of welding with impacting rotation is put forward to decrease the wave-like deformation of the TC4 thin plate weldment.The thermal stress and strain are vital to understand the mechanism of controlling the wave-like deformation.In order to know the development of internal thermal stress and strain,finite element method is utilized for the stress and strain are difficult to be investigated by experimental methods during the welding process.Temperature field,thermal stress evolution and distortion of thin plate are compared with the test results such as weld thermal cycle,residual stress sectioning measurement,and the deflection of the thin plate respectively.By the finite element analysis and test results verification,the mechanism of the technology to control the wave-like deformation is brought forward,non-uniform thermal elastic strain between compressive plastic region and elastic extensive region is diminished by a certain amount of extensive plastic deformation by welding with impacting rotation process.

  18. Gauge-meter model building based on the effect of elastic deformation of rolls in a plate mill

    Institute of Scientific and Technical Information of China (English)

    Xianlei Hu; Zhaodong Wang; Zhong Zhao; Xianghua Liu; Guodong Wang

    2007-01-01

    The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gaugemeter model.

  19. Analysis of Thermal Buckling of Ceramic-Metal Functionally Graded Plates Using Refined Third Order Shear Deformation Theory

    Directory of Open Access Journals (Sweden)

    S. S. Daimi

    2014-08-01

    Full Text Available Functionally graded materials (FGMs are microscopically inhomogeneous spatial composite materials, typically composed of a ceramic-metal or ceramic-polymer pair of materials. Therefore, it is important to investigate the behaviors of engineering structures such as beams and plates made from FGMs when they are subjected to thermal loads for appropriate design. Therefore, using an improved third order shear deformation theory (TSDT based on more rigorous kinetics of displacements to predict the behaviors of functionally graded plates is expected to be more suitable than using other theories. In this paper, the improved TSDT is used to investigate thermal buckling of functionally graded plates. Temperature dependent material property solutions are adopted to investigate thermal buckling results of functionally graded plates. To obtain the solutions, the Ritz method using polynomial and trigonometric functions for defining admissible displacements and rotations is applied to solve the governing equations.

  20. Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate boundary zone

    Science.gov (United States)

    van der Lelij, Roelant; Spikings, Richard A.; Kerr, Andrew C.; Kounov, Alexandre; Cosca, Michael; Chew, David; Villagomez, Diego

    2010-01-01

    Tectonic reconstructions of the Caribbean Plate are severely hampered by a paucity of geochronologic and exhumation constraints from anastomosed basement blocks along its southern margin. New U/Pb, 40Ar/39Ar, apatite fission track, and apatite (U-Th)/He data constrain quantitative thermal and exhumation histories, which have been used to propose a model for the tectonic evolution of the emergent parts of the Bonaire Block and the southern Caribbean Plate boundary zone. An east facing arc system intruded through an oceanic plateau during ~90 to ~87 Ma and crops out on Aruba. Subsequent structural displacements resulted in >80°C of cooling on Aruba during 70–60 Ma. In contrast, exhumation of the island arc sequence exposed on Bonaire occurred at 85–80 Ma and 55–45 Ma. Santonian exhumation on Bonaire occurred immediately subsequent to burial metamorphism and may have been driven by the collision of a west facing island arc with the Caribbean Plate. Island arc rocks intruded oceanic plateau rocks on Gran Roque at ~65 Ma and exhumed rapidly at 55–45 Ma. We attribute Maastrichtian-Danian exhumation on Aruba and early Eocene exhumation on Bonaire and Gran Roque to sequential diachronous accretion of their basement units to the South American Plate. Widespread unconformities indicate late Eocene subaerial exposure. Late Oligocene–early Miocene dextral transtension within the Bonaire Block drove subsidence and burial of crystalline basement rocks of the Leeward Antilles to ≤1 km. Late Miocene–recent transpression caused inversion and ≤1 km of exhumation, possibly as a result of the northward escape of the Maracaibo Block.

  1. Unsteady Hydromagnetic Flow past a Moving Vertical Plate with Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    Gauri Shanker Seth

    2016-01-01

    Full Text Available Investigation of unsteady MHD natural convection flow through a fluid-saturated porous medium of a viscous, incompressible, electrically-conducting and optically-thin radiating fluid past an impulsively moving semi-infinite vertical plate with convective surface boundary condition is carried out. With the aim to replicate practical situations, the heat transfer and thermal expansion coefficients are chosen to be constant and a new set of non-dimensional quantities and parameters are introduced to represent the governing equations along with initial and boundary conditions in dimensionless form. Solution of the initial boundary-value problem (IBVP is obtained by an efficient implicit finite-difference scheme of the Crank-Nicolson type which is one of the most popular schemes to solve IBVPs. The numerical values of fluid velocity and fluid temperature are depicted graphically whereas those of the shear stress at the wall, wall temperature and the wall heat transfer are presented in tabular form for various values of the pertinent flow parameters. A comparison with previously published papers is made for validation of the numerical code and the results are found to be in good agreement.

  2. Grain boundary void nucleation in astroloy produced by room temperature deformation and anneal

    Science.gov (United States)

    Saegusa, T.; Uemura, M.; Weertman, J. R.

    1980-08-01

    Dyson and co-workers have shown that the creep life of a nickel base superalloy can be greatly shortened if the material is strained at room temperature before the creep test is carried out. They found that a prestrain followed by a short annealing time produces small grain boundary cavities, and it is the presence of these prenucleated voids which so seriously degrades service life at elevated temperatures. The present work explores the relationship between microstructure and prestrain void nucleation. Samples of the nickel base superalloy astroloy were given various heat treatments which led to significantly different microstructures. It was found that voids resulting from a prestrain-anneal treatment form preferentially at the ends of carbides on grain boundaries oriented roughly parallel to the prestrain tensile axis or rolling direction. Void spacing in the various microstructures is proportional to (but larger than) carbide spacing. The growth of these cavities during annealing is attributed to the presence of tensile residual stresses arising from the difference in deformability between grain boundary regions and the relatively soft matrix.

  3. Geometry and brittle deformation of the subducting Nazca Plate, Central Chile and Argentina

    Science.gov (United States)

    Anderson, Megan; Alvarado, Patricia; Zandt, George; Beck, Susan

    2007-10-01

    We use data from the Chile Argentina Geophysical Experiment (CHARGE) broad-band seismic deployment to refine past observations of the geometry and deformation within the subducting slab in the South American subduction zone between 30°S and 36°S. This region contains a zone of flat slab subduction where the subducting Nazca Plate flattens at a depth of ~100 km and extends ~300 km eastward before continuing its descent into the mantle. We use a grid-search multiple-event earthquake relocation technique to relocate 1098 events within the subducting slab and generate contours of the Wadati-Benioff zone. These contours reflect slab geometries from previous studies of intermediate-depth seismicity in this region with some small but important deviations. Our hypocentres indicate that the shallowest portion of the flat slab is associated with the inferred location of the subducting Juan Fernández Ridge at 31°S and that the slab deepens both to the south and the north of this region. We have also determined first motion focal mechanisms for ~180 of the slab earthquakes. The subhorizontal T-axis solutions for these events are almost entirely consistent with a slab pull interpretation, especially when compared to our newly inferred slab geometry. Deviations of T-axes from the direction of slab dip may be explained with a gap within the subducting slab below 150 km in the vicinity of the transition from flat to normal subducting geometry around 33°S.

  4. Finite Element Analysis for Effect of Roll Radius on Metal Deformation of Hot Rolling Plate

    Institute of Scientific and Technical Information of China (English)

    LUO De-xing; CHEN Qi-an; LIU Li-wen

    2005-01-01

    The deformation of rolling piece in hot rolling by flat roll with different radii is analyzed with three-dimensional large deformation thermo-mechanical coupling finite element method. The distribution laws of stress, strain and strain energy density in deformation zone with rolls of different radii were studied. The result indicated that under the same condition, the larger the roll radius is, the more vigorous the deformation in deformation zone is.

  5. DEFORMATION RATE CHANGES OF TECTONIC BELTS ALONG BOUNDARIES OF YUNNAN SICHAUN BLOCK AND RELATION TO GROUPED STRONG EARTHQUAKES

    Institute of Scientific and Technical Information of China (English)

    ChengWanzheng; YangYongling

    2003-01-01

    Deformation measurements such as short-range leveling, short-baseline, continuous cross-fault strain measurement are carried out at different intervals from 1982 to 2001. All these measurement sites are built across the boundary tectonic belts of Yunnan-Sichuan block. On the basis of these deformation data, the annual deformation rates at all sites are calculated and their change curves with time are plotted respectively. With these calculated results, we analyze the vertical and horizontal movements of tectonic belts of Yunnan-Sichuan block, and the relationship to grouped strong earthquakes occurred in the block are discussed as well. These results show that the tectonic activities in the western and southeastern Yunnan are intensive. Along some eastern boundary belts: from Qujiang, Xiaojiang fault belts in the south of Yunnan to Xianshuihe fault belts in northwestern Sichuan, present annual rate of horizontal deformation decreases. Along Xianshuihe, Xiaojiang and Longmenshan fault belts the rates of vertical deformation change are small, but the vertical deformation change rates along Anninghe and Zemuhe faul tbelts are comparatively large. The comprehensive analysis shows that grouped strong earthquakes will occur probably when the deformation rate changes sharply. Thus we think that sharp changes of deformation rates may be one of the seismic precursors.

  6. DEFORMATION RATE CHANGES OF TECTONIC BELTS ALONG BOUNDARIES OF YUNNAN SICHAUN BLOCK AND RELATION TO GROUPED STRONG EARTHQUAKES

    Institute of Scientific and Technical Information of China (English)

    Cheng Wanzheng; Yang Yongling

    2003-01-01

    Deformation measurements such as short-range leveling, short-baseline, continuous cross-fault strain measurement are carried out at different intervals from 1982 to 2001. All these measurement sites are built across the boundary tectonic belts of Yunnan-Sichuan block. On the basis of these deformation data, the annual deformation rates at all sites are calculated and their change curves with time are plotted respectively. With these calculated results, we analyze the vertical and horizontal movements of tectonic belts of Yunnan-Sichuan block, and the relationship to grouped strong earthquakes occurred in the block are discussed as well. These results show that the tectonic activities in the western and southeastern Yunnan are intensive. Along some eastern boundary belts: from Qujiang, Xiaojiang fault belts in the south of Yunnan to Xianshuihe fault belts in northwestern Sichuan, present annual rate of horizontal deformation decreases. Along Xianshuihe, Xiaojiang and Longmenshan fault belts the rates of vertical deformation change are small, but the vertical deformation change rates along Anninghe and Zemuhe fault belts are comparatively large. The comprehensive analysis shows that grouped strong earthquakes will occur probably when the deformation rate changes sharply. Thus we think that sharp changes of deformation rates may be one of the seismic precursors.

  7. EarthScope Plate Boundary Observatory Data in the College Classroom (Invited)

    Science.gov (United States)

    Eriksson, S. C.; Olds, S. E.

    2009-12-01

    The Plate Boundary Observatory (PBO) is the geodetic component of the EarthScope project, designed to study the 3-D strain field across the active boundary zone between the Pacific and North American tectonics plates in the western United States. All PBO data are freely available to scientific and educational communities and have been incorporated into a variety of activities for college and university classrooms. UNAVCO Education and Outreach program staff have worked closely with faculty users, scientific researchers, and facility staff to create materials that are scientifically and technically accurate as well as useful to the classroom user. Availability of processed GPS data is not new to the geoscience community. However, PBO data staff have worked with education staff to deliver data that are readily accessible to educators. The UNAVCO Data for Educators webpage, incorporating an embedded Google Map with PBO GPS locations and providing current GPS time series plots and downloadable data, extends and updates the datasets available to our community. Google Earth allows the visualization GPS data with other types of datasets, e.g. LiDAR, while maintaining the self-contained and easy-to-use interface of UNAVCO’s Jules Verne Voyager map tools, which have multiple sets of geological and geophysical data. Curricular materials provide scaffolds for using EarthScope data in a variety of forms for different learning goals. Simple visualization of earthquake epicenters and locations of volcanoes can be used with velocity vectors to make simple deductions of plate boundary behaviors. Readily available time series plots provide opportunities for additional science skills, and there are web and paper-based support materials for downloading data, manipulating tables, and using plotting programs for processed GPS data. Scientists have provided contextual materials to explore the importance of these data in interpreting the structure and dynamics of the Earth. These data

  8. Experimental studies on the deformation and rupture of thin metal plates subject to underwater shock wave loading

    Directory of Open Access Journals (Sweden)

    Chen Pengwan

    2015-01-01

    Full Text Available In this paper, the dynamic deformation and rupture of thin metal plates subject to underwater shock wave loading are studied by using high-speed 3D digital image correlation (3D-DIC. An equivalent device consist of a gas gun and a water anvil tube was used to supplying an exponentially decaying pressure in lieu of explosive detonation which acted on the panel specimen. The thin metal plate is clamped on the end of the shock tube by a flange. The deformation and rupture process of the metal plates subject to underwater shock waves are recorded by two high-speed cameras. The shape, displacement fields and strain fields of the metal plates under dynamic loading are obtained by using VIC-3D digital image correlation software. The strain gauges also were used to monitor the structural response on the selected position for comparison. The DIC data and the strain gauges results show a high level of correlation, and 3D-DIC is proven to be an effective method to measure 3D full-field dynamic response of structures under underwater impact loading. The effects of pre-notches on the failure modes of thin circular plate were also discussed.

  9. The fluid budget of a continental plate boundary fault: Quantification from the Alpine Fault, New Zealand

    Science.gov (United States)

    Menzies, Catriona D.; Teagle, Damon A. H.; Niedermann, Samuel; Cox, Simon C.; Craw, Dave; Zimmer, Martin; Cooper, Matthew J.; Erzinger, Jörg

    2016-07-01

    Fluids play a key role in modifying the chemical and physical properties of fault zones, which may prime them for repeated rupture by the generation of high pore fluid pressures and precipitation of commonly weak, secondary minerals. Fluid flow paths, sources and fluxes, and the permeability evolution of fault zones throughout their seismic cycles remain poorly constrained, despite their importance to understanding fault zone behaviour. Here we use geochemical tracers of fluid-rock exchange to determine budgets for meteoric, metamorphic and mantle fluids on a major compressional tectonic plate boundary. The Alpine Fault marks the transpressional Pacific-Australian plate boundary through South Island, New Zealand and appears to fail in regular (329 ± 68 yrs) large earthquakes (Mw ∼ 8) with the most recent event in 1717 AD. Significant convergent motion has formed the Southern Alps and elevated geothermal gradients in the hangingwall, which drive crustal fluid flow. Along the Alpine Fault the Alpine Schist of the Pacific Plate is thrust over radiogenic metasedimentary rocks on the Australian plate. The absence of highly radiogenic (87Sr/86Sr > 0.7200) strontium isotope ratios of hangingwall hot springs and hydrothermal minerals formed at a range of depths in the Alpine Fault damage zone indicates that the fluid flow is restricted to the hangingwall by a cross-fault fluid flow barrier throughout the seismogenic crust. Helium isotope ratios measured in hot springs near to the Alpine Fault (0.15-0.81 RA) indicate the fault is a crustal-scale feature that acts as a conduit for fluids from the mantle. Rock-exchanged oxygen, but meteoric water-like hydrogen isotope signatures of hydrothermal veins indicate that partially rock-exchanged meteoric fluids dominate down to the top of the brittle to ductile transition zone at ∼6 km. Geochemical tracer transport modelling suggests only ∼0.02 to 0.05% of total rainfall west of the Main Divide penetrates to depth, yet this

  10. Laboratory-observed frictional slip instabilities in samples of the Tohoku plate boundary megathrust

    Science.gov (United States)

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

    2014-12-01

    The plate boundary megathrust at the Japan Trench is remarkable due to its capability for a wide range of fault slip styles. In addition to the extraordinarily large amount of coseismic slip (several 10's of meters) that reached the seafloor during the 2011 Tohoku-Oki earthquake, the the Japan Trench is also known host slow earthquakes. The location of these slow earthquakes coincide with the rupture area of the 2011 Tohoku earthquake; one was observed to occur in the month before the 2011 earthquake and was likely ongoing during the earthquake. This shows that the frictional behavior of the Japan Trench megathrust is complex and thus failure can occur in a variety of styles. Samples of the plate boundary fault zone in the Tohoku region were recovered ~7 km from the Japan Trench axis, within the region of largest coseismic slip during the Tohoku earthquakes, during Integrated Ocean Drilling Program Expedition 343, the Japan Trench Fast Drilling Project (JFAST). We used these samples in laboratory friction experiments in order to examine the slip behavior of the shallow Tohoku megathrust. In our tests, we sheared the samples at 10 μm/s to establish a steady shear geometry and friction level and subsequently decrease the slip velocity to 2.7 nm/s, equal to the convergence rate between the Pacific and North American plates (85 mm/yr) and thus simulating realistically slow fault slip rates. Regular stick-slip behavior was observed soon after the velocity decrease but ceases as friction evolves to a new residual level. Shearing then mostly proceeds as stable creep, however infrequent friction perturbations are observed which occur two to three times over several mm. Unlike normal stick-slip behavior, we observe stress increases before the stress drop so that the friction level before and after the event are similar. The stress drop is ~0.015 in friction (~100 kPa) and occurs over several hours; therefore we interpret these events to be laboratory-generated slow

  11. Detection of Reflected Waves from Plate Boundary Using ACROSS Source and Seismic Array

    Science.gov (United States)

    Soma, T.; Watanabe, T.; Ikuta, R.; Saiga, A.; Miyajima, R.; Yamaoka, K.; Tsuruga, K.; Kunitomo, T.; Hasada, Y.; Kasahara, J.; Satomura, M.; Kumazawa, M.; Fujii, N.

    2005-12-01

    ACROSS (Accurately Controlled and Routinely Operated Signal System) is effective in monitoring temporary changes of Earth's interior. A long-term operation experiment near Nojima fault [Ikuta et al.,2004] detected small temporary changes of travel time of P and S waves at tele-seismic events. Toward Tokai monitoring plan to detect the reflected phases from the top of Philippine Sea Plate and monitor its temporal changes, a mid-term continuous experiment was conducted using ACROSS source and a seismic array. The experiment was operated for the period from Dec. 2004 to Sep.2005 in the Tokai area, Pacific side of the central part of Japan. In this region, the expected Tokai earthquake is a serious concern. In addition, slow slip events and low-frequency tremors are observed in this area. A strong reflected phase from the plate boundary was found by the seismic observation using artificial sources [Iidaka et al.,2003]. The purpose of the experiment is to establish a method to detect and monitor the reflection from the plate boundary using ACROSS. The ACROSS source is located in Toki city and operated by Tono Geoscience Center. The ACROSS source continuously transmits precisely-controlled frequency-modulated signals whose frequency band ranges from 10 to 20 Hz with an interval of 50 seconds. We deployed a short-span seismic array at the distance of 55 km from the ACROSS source. The cross-shaped seismic array spanning 2 km consists of 12 seismometers equipped with an offline data logger, amplifier and solarpanel. We stacked the received signal for a month with an interval of 200 seconds in order to improve signal noise ratio. We extracted a series of line spectrum of ACROSS signal. Transfer function can be obtained by dividing spectrum by the source. Applying inverse Fourier transform, we can obtain the transfer function in time-domain. We identified direct P and S phases by comparing with the standard travel time table by JMA. We also found some coherent later phases

  12. Isla Guadalupe, a Plate Boundary Observatory Remote GPS System: What's Next in PBO-Mexico?

    Science.gov (United States)

    Gonzalez Garcia, J.

    2003-12-01

    As a join project between scientific and technical personnel from Southern California Integrated GPS Network, the University NAVSTAR Consortium, Nanometrics Inc, and CICESE, we installed a VSAT remote communications on Isla Guadalupe in support of data telemetry from a cluster of GPS, meteorological and seismic instrumentation. This Mexican island located between 28\\deg53' and 29\\deg 11'N and 118\\deg 13' to 118\\deg 22'W, lies too far from the main land to allow regular radio link. The station now in operation (GUAX) is near of the early GEOMEX site (GUAD), which recent GPS survey mode result show, is fully located on the Pacific plate within the prediction (1 mm/yr N and 2 mm/yr E) of both the geophysical (NNR-NUVEL1-A) and geodetic (ITRF2000) Plate Tectonic models. Thus, GUAX serve as an important clue to accurately monitor the plate's motion, as well as a reference for studies of California Borderland deformation. During the last 5 years we have built two more sites in northern Baja California: SPMX (1998) and CORX (2000); these together with the IGS station in Ensenada (CICE established in 1995 and replaced by CIC1 in 1999), became part of SCIGN-SOPAC (http://sopac.ucsd.edu, www.scign.org). In Mexico the major organizations working with GPS are INEGI (15 sites) and UNAM (different groups: 20-25 sites). Other State Universities and agencies are increasingly using permanent GPS stations for diverse purposes. It seems that in order to achieve our commitment for PBO-Mexico we must to follow the PGGA/SCIGN/CSRC waybill.

  13. The Ionian and Alfeo-Etna fault zones : New segments of an evolving plate boundary in the central Mediterranean Sea?

    NARCIS (Netherlands)

    Polonia, A.; Torelli, L.; Artoni, A.; Carlini, M.; Faccenna, C.; Ferranti, L.; Gasperini, L.; Govers, R.; Klaeschen, D.; Monaco, C.; Neri, G.; Nijholt, N.; Orecchio, B.; Wortel, R.

    2016-01-01

    The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the NNW

  14. The Ionian and Alfeo-Etna fault zones : New segments of an evolving plate boundary in the central Mediterranean Sea?

    NARCIS (Netherlands)

    Polonia, A.; Torelli, L.; Artoni, A.; Carlini, M.; Faccenna, C.; Ferranti, L.; Gasperini, L.; Govers, R.|info:eu-repo/dai/nl/108173836; Klaeschen, D.; Monaco, C.; Neri, G.; Nijholt, N.; Orecchio, B.; Wortel, R.|info:eu-repo/dai/nl/068439202

    2016-01-01

    The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the NNW

  15. Non-equilibrium grain boundaries in titanium nanostructured by severe plastic deformation: Computational study of sources of material strengthening

    DEFF Research Database (Denmark)

    Liu, Hongsheng; Mishnaevsky, Leon; Pantleon, Wolfgang

    2014-01-01

    A computational model of ultrafine grained (UFG) or nanostructured titanium (Ti), based on a finite element (FE) unit cell model of the material and a dislocation density based model of plastic deformation has been developed. FE simulations of tensile deformation of UFG Ti with different fractions...... and properties of the grain boundary (GB) phase have been carried out. The effect of different degrees of deviation from the equilibrium state of the grain boundaries (GBs) on the mechanical behaviour of nanostructured Ti have been investigated using the combined composite/dislocation dynamics based model....... In particular, the effects of different diffusion coefficients in the GB phase, of a high initial dislocation density in the grain boundaries, as well as of atomic scale precipitates are investigated for affecting the deformation behaviour of UFG or nanostructured Ti. © 2013 Elsevier B.V. All rights reserved....

  16. Plate convergence, crustal delamination, extrusion tectonics and minimization of shortening work as main controlling factors of the recent Mediterranean deformation pattern

    Directory of Open Access Journals (Sweden)

    D. Babbucci

    1997-06-01

    Full Text Available It is argued that the time-space distribution of major post middle Miocene deformation events in the Central-Eastern Mediterranean region, deduced from the relevant literature, can be coherently explained as a consequence of the convergence between the Africa/Arabia and Eurasia blocks. This plate convergence has mainly been accommodated by the consumption of the thinnest parts of the Northern African (Ionian and Levantine basins and peri-Adriatic margins. During each evolutionary phase the space distribution of trench zones is controlled by the basic physical requirement of minimizing the work of horizontal forces, induced by plate convergence, against the resisting forces, i.e., the cohesion of the upper brittle crustal layer and the buoyancy forces at the consuming boundaries. The significant changes of tectonic styles which determined the transition from one phase to the next, like those which occurred around the Messinian and the late Pliocene-early Pleistocene, were determined by the suture of consuming boundaries. When such an event occurs, the system must activate alternative consuming processes to accommodate the convergence of the major confining blocks. The observed deformations in the study area suggest that this tectonic reorganization mostly developed by the lateral extrusion of crustal wedges away from the sutured borders. This mechanism allowed the translation of maximum horizontal stresses from the locked collisional fronts to the zones where consumable lithosphere was still present, in order to activate the next consuming processes. The extensional episodes which led to the formation of basins and troughs in the Tyrrhenian and Aegean zones are interpreted as secondary effects of the outward escape of crustal wedges, like those which occurred in response to longitudinal compressional regimes in the Apennines and Aegean regions.

  17. Tectonic lineaments in the cenozoic volcanics of southern Guatemala: Evidence for a broad continental plate boundary zone

    Science.gov (United States)

    Baltuck, M.; Dixon, T. H.

    1984-01-01

    The northern Caribbean plate boundary has been undergoing left lateral strike slip motion since middle Tertiary time. The western part of the boundary occurs in a complex tectonic zone in the continental crust of Guatemala and southernmost Mexico, along the Chixoy-Polochic, Motogua and possibly Jocotan-Chamelecon faults. Prominent lineaments visible in radar imagery in the Neogene volcanic belt of southern Guatemala and western El Salvador were mapped and interpreted to suggest southwest extensions of this already broad plate boundary zone. Because these extensions can be traced beneath Quaternary volcanic cover, it is thought that this newly mapped fault zone is active and is accommodating some of the strain related to motion between the North American and Caribbean plates. Onshore exposures of the Motoqua-Polochic fault systems are characterized by abundant, tectonically emplaced ultramafic rocks. A similar mode of emplacement for these off shore ultramafics, is suggested.

  18. Plate tectonics and offshore boundary delimitation: Tunisia-Libya case at the International Court of Justice

    Science.gov (United States)

    Stanley, Daniel Jean

    1982-03-01

    The first major offshore boundary dispute where plate tectonics constituted a significant argument was recently brought before the International Court of Justice by Libya and Tunisia concerning the delimitation of their continental shelves. Libya placed emphasis on this concept to determine natural prolongation of its land territory under the sea. Tunisia contested use of the entire African continental landmass as a reference unit and views geography, geomorphology and bathymetry as relevant as geology. The Court pronounced that “It is the outcome, not the evolution in the long-distant past, which is of importance.” Moreover, it is the present-day configuration of coasts and seabed that are the main factors, not geology.

  19. Abrupt thermal transition reveals hydrothermal boundary and role of seamounts within the Cocos Plate

    Science.gov (United States)

    Fisher, A. T.; Stein, C. A.; Harris, R. N.; Wang, K.; Silver, E. A.; Pfender, M.; Hutnak, M.; Cherkaoui, A.; Bodzin, R.; Villinger, H.

    2003-06-01

    New thermal data from 18-24 Ma lithosphere on the Cocos Plate delineate contrasting subsurface thermal conditions in adjacent sections of crust. Heat flow through seafloor created at the East Pacific Rise is generally suppressed by ~70% relative to conductive lithospheric cooling models, whereas heat flow through adjacent, similarly-aged lithosphere generated at the Cocos-Nazca Spreading Center is consistent with these models. The transition between thermal regimes is remarkably abrupt, only 2-5 km wide, indicating a shallow hydrothermal origin. The transition is more closely associated with differences in the distribution of basement outcrops than with tectonic boundaries, demonstrating the importance of the former in extracting heat from the lithosphere on a regional basis.

  20. Homotopy deform method for reproducing kernel space for nonlinear boundary value problems

    Indian Academy of Sciences (India)

    MIN-QIANG XU; YING-ZHEN LIN

    2016-10-01

    In this paper, the combination of homotopy deform method (HDM) and simplified reproducing kernel method (SRKM) is introduced for solving the boundary value problems (BVPs) of nonlinear differential equations. The solution methodology is based on Adomian decomposition and reproducing kernel method (RKM). By the HDM, the nonlinear equations can be converted into a series of linear BVPs. After that, the simplified reproducing kernel method, which not only facilitates the reproducing kernel but also avoids the time-consuming Schmidt orthogonalization process, is proposed to solve linear equations. Some numerical test problems including ordinary differential equations and partial differential equations are analysed to illustrate the procedure and confirm the performance of the proposed method. The results faithfully reveal that our algorithm is considerably accurate and effective as expected.

  1. Recovering physical property information from subduction plate boundaries using 3D full-waveform seismic inversion

    Science.gov (United States)

    Bell, R. E.; Morgan, J. V.; Warner, M.

    2013-12-01

    Our understanding of subduction margin seismogenesis has been revolutionised in the last couple of decades with the discovery that the size of the seismogenic zone may not be controlled simply by temperature and a broad spectrum of seismic behaviour exists from stick-slip to stable sliding. Laboratory and numerical experiments suggest that physical properties, particularly fluid pressure may play an important role in controlling the seismic behaviour of subduction margins. Although drilling can provide information on physical properties along subduction thrust faults at point locations at relatively shallow depths, correlations between physical properties and seismic velocity using rock physics relationships are required to resolve physical properties along the margin and down-dip. Therefore, high resolution seismic velocity models are key to recovering physical property information at subduction plate boundaries away from drill sites. 3D Full waveform inversion (FWI) is a technique pioneered by the oil industry to obtain high-resolution high-fidelity models of physical properties in the sub-surface. 3D FWI involves the inversion of low-frequency (>2 to noise and inverted the windowed transmitted arrivals only. We also ran a suite of resolution tests across the model. The results show that 3D FWI of conventionally collected 3D seismic data across the Muroto Basin would be capable of resolving variations in P-wave velocity along the décollement of the order of half the seismic wavelength at the plate boundary. This is a significant improvement on conventional travel-time tomography which resolves to the Fresnel width. In this presentation we will also postulate on the optimal 3D FWI experiment design for the next generation of 3D seismic surveys across subduction margins as a guide for those embarking on new data collection.

  2. A mixed problem of plate bending for doubly connected domains with partially unknown boundaries in the presence of cyclic symmetry

    Institute of Scientific and Technical Information of China (English)

    Odishelidze; N; Criado-Aldeanueva; F

    2010-01-01

    This paper addresses the problem of plate bending for a doubly connected body with outer and inner boundaries in the form of regular polygons with a common center and parallel sides.The neighborhoods of the vertices of the inner boundary are equal full-strength smooth arcs symmetric about the rays coming from the vertices to the center,but have unknown positions.Rigid bars are attached to the linear parts of the boundary.The plate bends by the moments applied to the middle point bars.The unknown arcs are free from external stresses.The same problem of plate bending is considered for a regular hexagon weakened by a full-strength hole.Using the methods of complex analysis,the analytical image of Kolosov-Muskhelishvili’s complex potentials (characterizing an elastic equilibrium of the body),the plate deflection and unknown parts of its boundary are determined under the condition that the tangential normal moment on that plate takes a constant value.Numerical analyses are also performed and the corresponding graphs are constructed.

  3. Geophysical surveys of the Queen Charlotte Fault plate boundary off SE Alaska: Preliminary results

    Science.gov (United States)

    Ten Brink, U. S.; Brothers, D. S.; Andrews, B. D.; Kluesner, J.; Haeussler, P. J.; Miller, N. C.; Watt, J. T.; Dartnell, P.; East, A. E.

    2016-12-01

    Recent multibeam sonar and high-resolution seismic surveys covering the northern 400-km-long segment of Queen Charlotte Fault off SE Alaska, indicate that the entire 50 mm/yr right-lateral Pacific-North America plate motion is currently accommodated by a single fault trace. The trace is remarkably straight rarely interrupted by step-overs, and is often Internal basin stratigraphy indicates possible southward migration of the step-over with time. Slight outward curving of the southern strand may suggest the presence of a deeper barrier there, which could have terminated the northward super-shear rupture of the 2013 M7.5 Craig Earthquake. Whether this possible barrier is related to the intersection of the Aja Fracture Zone with the plate boundary is unclear. No other surficial impediments to rupture were observed along the 315 km trace between this fault step-over and a 20° bend near Icy Point, where the fault extends onshore and becomes highly transpressional. An enigmatic oval depression, 1.5-2 km wide and 500 m deep, south of the step-over and a possible mud volcano north of the step-over, may attest to possible vigorous gas and fluid upwelling along the fault zone.

  4. Deformation mechanism of kink-step distorted coherent twin boundaries in copper nanowire

    Directory of Open Access Journals (Sweden)

    Bobin Xing

    2017-01-01

    Full Text Available In the construction of nanotwinned (NT copper, inherent kink-like steps are formed on growth twin boundaries (TBs. Such imperfections in TBs play a crucial role in the yielding mechanism and plastic deformation of NT copper. Here, we used the molecular dynamic (MD method to examine the influence of kink-step characteristics in depth, including kink density and kink-step height, on mechanical behavior of copper nanowire (NW in uniaxial tension. The results showed that the kink-step, a stress-concentrated region, is preferential in nucleating and emitting stress-induced partial dislocations. Mixed dislocation of hard mode I and II and hard mode II dislocation were nucleated from kink-step and surface atoms, respectively. Kink-step height and kink density substantially affected the yielding mechanism and plastic behavior, with the yielding stress functional-related to kink-step height. However, intense kink density (1 kink per 4.4 nm encourages dislocation nucleation at kink-steps without any significant decline in tensile stress. Defective nanowires with low kink-step height or high kink density offered minimal resistance to kink migration, which has been identified as one of the primary mechanisms of plastic deformation. Defective NWs with refined TB spacing were also studied. A strain-hardening effect due to the refined TB spacing and dislocation pinning was observed for defective NWs. This study has implications for designing NT copper to obtain optimum mechanical performance.

  5. Abbot Ice Shelf, structure of the Amundsen Sea continental margin and the southern boundary of the Bellingshausen Plate seaward of West Antarctica.

    Science.gov (United States)

    Cochran, James R; Tinto, Kirsty J; Bell, Robin E

    2015-05-01

    Inversion of NASA Operation IceBridge airborne gravity over the Abbot Ice Shelf in West Antarctica for subice bathymetry defines an extensional terrain made up of east-west trending rift basins formed during the early stages of Antarctica/Zealandia rifting. Extension is minor, as rifting jumped north of Thurston Island early in the rifting process. The Amundsen Sea Embayment continental shelf west of the rifted terrain is underlain by a deeper, more extensive sedimentary basin also formed during rifting between Antarctica and Zealandia. A well-defined boundary zone separates the mildly extended Abbot extensional terrain from the deeper Amundsen Embayment shelf basin. The shelf basin has an extension factor, β, of 1.5-1.7 with 80-100 km of extension occurring across an area now 250 km wide. Following this extension, rifting centered north of the present shelf edge and proceeded to continental rupture. Since then, the Amundsen Embayment continental shelf appears to have been tectonically quiescent and shaped by subsidence, sedimentation, and the advance and retreat of the West Antarctic Ice Sheet. The Bellingshausen Plate was located seaward of the Amundsen Sea margin prior to incorporation into the Antarctic Plate at about 62 Ma. During the latter part of its independent existence, Bellingshausen plate motion had a clockwise rotational component relative to Antarctica producing convergence across the north-south trending Bellingshausen Gravity Anomaly structure at 94°W and compressive deformation on the continental slope between 94°W and 102°W. Farther west, the relative motion was extensional along an east-west trending zone occupied by the Marie Byrd Seamounts. Abbot Ice Shelf is underlain by E-W rift basins created at ∼90 Ma Amundsen shelf shaped by subsidence, sedimentation, and passage of the ice sheet Bellingshausen plate boundary is located near the base of continental slope and rise.

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

    Science.gov (United States)

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

    2015-04-01

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

  7. What do Great Subduction Earthquakes tell us About Continental Deformation of the Upper Plate in the Central Andes Forearc? Insights From Seismotectonics, Continental Deformation and Coulomb Modelisation Along Southern Peru Margin

    Science.gov (United States)

    Audin, L.; Perfettini, H.; Tavera, H.

    2007-05-01

    Subduction of the Nazca plate beneath the Peruvian margin has produced numerous megathrust earthquakes during the last century and still constitutes mature seismic gaps in some places such as in between Ilo (Peru) and Arica (Chile). The rupture zones of the 1604, 1784 and 1868 southern Peru events were partially reactivated by the Arequipa 2001 (Mw = 8.5) seismic event, whose rupture zone was about 350km-long and stopped its propagation towards the south on Ilo Peninsula. Just after the occurrence of 2001 event, some reactivation of continental fault systems are identified and monitored thanks to the Peruvian seismic network and describe continental deformation processes occurring perpendicularly to the trench or parallel to the trench, traducing the continental plate response to major subduction earthquakes and some partitioning of the deformation. The Chololo and associated ( perpendicular to the trench) fault systems define some 80-km-long margin crustal blocks and the major one coincides with the 2001 earthquake southern limit of the rupture zone as it propagated to the south. These blocks are made from Late Jurassic and Cretaceous plutonic rocks from the Coastal Batholith; these are outcropping in some places and are evidenced by the aeromagnetic mapping elsewhere around the area. Northward along the subduction zone, another boundary between two rupture zones of major subduction earthquake was reactivated recently, perpendicularly to the trench, by the seismic crisis of October 2006, M=6.4, near Lima, right at the southern end of the rupture zone of the 1974 event (Mw=8.1).Those boundaries corresponding to discontinuities (lithospheric fault systems) in the upper plate, trending nearly perpendicular to the trench, act as earthquake barriers during rupture of large seismic events. Additionally occurred on 20 of November 2006 another seismic event (Mw=5.6 Neic, Ml=5.3) in Tacna region, showing a reverse focal mechanism compatible with the trend of the Sama

  8. Natural convective boundary layer flow of a nano-fluid past a convectively heated vertical plate

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, A. [Department of Mechanical Engineering, School of Engineering and Applied Science, Gonzaga University, Spokane, WA 99258 (United States); Khan, W.A. [Department of Engineering Sciences, PN Engineering College, National University of Sciences and Technology, Karachi 75350 (Pakistan)

    2012-03-15

    Natural convective flow of a nano-fluid over a convectively heated vertical plate is investigated using a similarity analysis of the transport equations followed by their numerical computations. The transport model employed includes the effect of Brownian motion and thermophoresis. The analysis shows that velocity, temperature and solid volume fraction of the nano-fluid profiles in the respective boundary layers depend, besides the Prandtl and Lewis numbers, on four additional dimensionless parameters, namely a Brownian motion parameter Nb, a thermophoresis parameter Nt, a buoyancy-ratio parameter Nr and convective parameter Nc. In addition to the study of these parameters on the boundary layer flow characteristics (velocity, temperature, solid volume fraction of the nano-fluid, skin friction, and heat transfer), correlations for the Nusselt and Sherwood numbers have been developed based on a regression analysis of the data. These linear regression models provide a highly accurate (with a maximum standard error of 0.004) representation of the numerical data and can be conveniently used in engineering practice. (authors)

  9. Boundary Layer of Photon Absorption Applied to Heterogeneous Photocatalytic Solar Flat Plate Reactor Design

    Directory of Open Access Journals (Sweden)

    Héctor L. Otálvaro-Marín

    2014-01-01

    Full Text Available This study provides information to design heterogeneous photocatalytic solar reactors with flat plate geometry used in treatment of effluents and conversion of biomass to hydrogen. The concept of boundary layer of photon absorption taking into account the efficient absorption of radiant energy was introduced; this concept can be understood as the reactor thickness measured from the irradiated surface where 99% of total energy is absorbed. Its thickness and the volumetric rate of photons absorption (VRPA were used as design parameters to determine (i reactor thickness, (ii maximum absorbed radiant energy, and (iii the optimal catalyst concentration. Six different commercial brands of titanium dioxide were studied: Evonik-Degussa P-25, Aldrich, Merck, Hombikat, Fluka, and Fisher. The local volumetric rate of photon absorption (LVRPA inside the reactor was described using six-flux absorption-scattering model (SFM applied to solar radiation. The radiation field and the boundary layer thickness of photon absorption were simulated with absorption and dispersion effects of catalysts in water at different catalyst loadings. The relationship between catalyst loading and reactor thickness that maximizes the absorption of radiant energy was obtained for each catalyst by apparent optical thickness. The optimum concentration of photocatalyst Degussa P-25 was 0.2 g/l in 0.86 cm of thickness, and for photocatalyst Aldrich it was 0.3 g/l in 0.80 cm of thickness.

  10. Towards understanding earthquake nucleation on a severely misoriented plate boundary fault, Alpine Fault, New Zealand

    Science.gov (United States)

    Boulton, C. J.; Faulkner, D. R.; Allen, M. J.; Coussens, J.; Menzies, C. D.; Mariani, E.

    2016-12-01

    New Zealand's Alpine Fault has accommodated relative motion between the Australian and Pacific plates for over 23 million years: first as strike-slip fault and then as an oblique transpressional fault. Despite being driven by principal stresses whose orientations have undoubtedly changed with time, the Alpine Fault continues to accommodate 70% of the relative plate boundary motion. Fault outcrop data and seismic reflection data indicate that the central Alpine Fault is consistently oriented 055/45°SE at depths up to 15 km (i.e., throughout the seismogenic zone); focal mechanisms indicate that the stress tensor is oriented σ1=σHmax=0/117°, σ2=σv, and σ3=0/207° (Boese et al. 2013, doi: 10.1016/j.epsl.2013.06.030). At depth, the central Alpine Fault lies at an angle of 51° to σ1. The Mohr-Coulomb failure criterion stipulates that, for incohesive rocks, reactivation of a fault requires sufficient driving stress to overcome frictional resistance to slip. Using a coefficient of friction (μ) of 0.6, as measured for representative Alpine Fault rocks under in situ conditions (Neimeijer et al. 2016, doi:10.1002/2015JB012593), and an estimated stress shape ratio (Φ=(σ2 - σ3)/(σ1 - σ3)=0.5), a 3-D reactivation analysis was performed (Leclère and Fabbri 2013, doi:10.1016/j.jsg.2012.11.004). Results show that the Alpine Fault is severely misoriented for failure, requiring pore fluid pressures greater than the least principal stress to initiate frictional sliding. However, microstructural evidence, including pseudotachylytes and fault gouge injection structures, suggests that earthquakes nucleate and propagate along this major plate boundary fault. By assuming an increase in differential stress of 15 MPa/km, our analysis shows that reactivation may occur with suprahydrostatic pore fluid pressures given a ≥10° counterclockwise rotation of σHmax. Using measured hydraulic data, we estimate the potential for pore fluid overpressure development within the Alpine

  11. Subsurface deformation and the role of surface texture—A study with Cu pins and steel plates

    Indian Academy of Sciences (India)

    Pradeep L Menezes; Kishore; Satish V Kailas

    2008-06-01

    The extent of subsurface deformation below the worn surface influences friction and transfer layer formation during sliding. Thus, in this study, the extent of plastic deformation and strain localization events that occur at various depths beneath the worn surface in the subsurface zones of Cu pins slid against steel plate with various surface textures have been determined using simple metallographic techniques. Results showed that the magnitude of plastic strain gradient and the depth of highly deformed zone depend on both coefficient of friction and transfer layer formation, which in-turn depends on the surface texture of harder counterface, under both dry and lubricated conditions. In addition, it was seen that the gradient of equivalent strain, as it approached the worn surface, was higher under dry conditions when compared to that under lubricated conditions.

  12. Parametric study of the deformation of dispersion fuel plates; Estudo parametrico da deformacao de placas combustiveis com nucleos de dispersao

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, E.; Durazzo, M., E-mail: evieira@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    The Nuclear and Energy Research Institute - IPEN-CNEN/SP produces routinely the nuclear fuel necessary for operating its research reactor, IEA-R1. This fuel consists of fuel plates containing U{sub 3}Si{sub 2}-Al composites as the meat, which are fabricated by rolling. The rolling process currently deployed was developed with base on information obtained from literature, which were used as premises for defining the current manufacturing procedures, according to a methodology with essentially empirical character. Despite the current rolling process to be perfectly stable and highly reproducible, it is not well characterized and therefore is not fully known. The objective of this work is to characterize the rolling process for producing fuel plates, presenting results of the evolution of all parameters of technological interest, after each rolling pass, obtaining information along the fuel plate deformation during the rolling process. (author)

  13. Effect of strain-weakening on Oligocene-Miocene self-organization of the Australian-Pacific plate boundary fault in southern New Zealand: Insights from numerical modelling

    Science.gov (United States)

    Feng, Xiaojun; Jessell, Mark Walter; Amponsah, Prince Ofori; Martin, Roland; Ganne, Jérôme; Liu, Daqing; Batt, Geoffrey E.

    2016-10-01

    Tectonic inheritance acquired from past geological events can control the formation of new plate boundaries. The aim of this paper is to explore the role of inherited NE and NW trending fabrics and their rheological influence on the propagation of Oligocene-Miocene strike-slip faulting that matured to become the Australian-Pacific plate boundary fault in southern New Zealand. Strain weakening plays a significant role in controlling the formation, growth and evolution of strain localization. In this study, three-dimensional thermo-mechanical models have been used to explore the effect of strain weakening on the Oligocene-Miocene self-organization of strain localization. Strain weakening is simulated through decreasing either the coefficient of friction of upper crust, its cohesion, or the rheological viscosity contrast between the inherited structures and their surrounding wall rocks. Viscosity contrast is obtained by varying the viscosity of inherited structures. Softening coefficient (α) is a measure of strain weakening. Our experiments robustly demonstrate that a primary boundary shear zone becomes mature quicker when softening coefficients are increased. Deformation is focused along narrow high-strain shear zones in the centre of the model when the softening coefficients are high, whereas the strain is more diffuse with many shear zones spread over the model and possibly some high-strain shear zones focused near one border at lower softening coefficients. Varying the viscosity contrast has less effect on the distribution of maximum finite strain. Under simple-shear boundary conditions, NW trending inherited structures make a major contribution to forming early zones of highly focused strain, up to a shear strain of about γ = 3.7. During this process, most NE-trending structures move and rotate passively, accommodate less strain, or even be abandoned through time.

  14. Low-latency high-rate GPS data streams from the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Anderson, G.; Borsa, A.; Jackson, M.; Stark, K.

    2008-05-01

    Real-time processing of high rate GPS data can give precise (e.g., 5-10 mm for data recorded once per second) recordings of rapid volcanic and seismic deformation. These time series now provide an emerging tool for seismic, volcanic, and tsunami geodesy and early warning applications. UNAVCO, as part of the EarthScope Plate Boundary Observatory project, has developed the UStream system to provide streaming GPS data from some PBO and other UNAVCO-operated GPS stations. UStream is based on the Ntrip standard, a widely used protocol for streaming GNSS data over the Internet. Remote GPS stations provide a stream of BINEX data at 1 sample/sec to an Ntrip server at UNAVCO's Boulder offices, while simultaneously recording data locally in the event of communications failure. Once in Boulder, the data fork into three output streams: BINEX files stored at UNAVCO and streams of data in BINEX and RTCM 2.3 format. These streams flow to an Ntrip broadcaster that distributes data to Ntrip clients, which can be anything from low-latency processing systems to external data archiving systems. Current development efforts are geared toward providing data in RTCM 3.x format. This system is now operating in a public beta test mode, with data available from over 55 PBO and Nucleus GPS stations across the western United States. Data latencies from stations operating on mobile telephone communications are under 1.1 seconds at 95% confidence, and data completeness is typically more than 95% barring transient communications disruptions. Data from the system are available under the terms of the draft UNAVCO streaming data usage policy. For further information, please visit http://rtgps.unavco.org or send e-mail to rtgps@unavco.org.

  15. Correction of coronal plane deformities around the knee using a tension band plate in children younger than 10 years

    Directory of Open Access Journals (Sweden)

    Ruta M Kulkarni

    2015-01-01

    Full Text Available Background: Guided growth through temporary hemiepiphysiodesis has gained acceptance as the preferred primary treatment in treating pediatric lower limb deformities as it is minimally invasive with a lesser morbidity than the traditional osteotomy. The tension band plate is the most recent development in implants used for temporary hemiepiphysiodesis. Our aim was to determine its safety and efficacy in correcting coronal plane deformities around the knee in children younger than 10 years. Materials and Methods: A total of 24 children under the age of 10 were operated for coronal plane deformities around the knee with a single extra periosteal tension band plate and two nonlocking screws. All the children had a pathological deformity for which a detailed preoperative work-up was carried out to ascertain the cause of the deformity and rule out physiological ones. The average age at hemiepiphysiodesis was 5 years 3 months (range: 2 years to 9 years 1 month. Results: The plates were inserted for an average of 15.625 months (range: 7 months to 29 months. All the patients showed improvement in the mechanical axis. Two patients showed partial correction. Two cases of screw loosening were observed. In the genu valgum group, the tibiofemoral angle improved from a preoperative mean of 19.89° valgus (range: 10° valgus to 40° valgus to 5.72° valgus (range: 2° varus to 10° valgus. In patients with genu varum the tibiofemoral angle improved from a mean of 28.27° varus (range: 13° varus to 41° varus to 1.59° valgus (range: 0-8° valgus. Conclusion: Temporary hemiepiphysiodesis through the application of the tension band plate is an effective method to correct coronal plane deformities around the knee with minimal complications. Its ease and accuracy of insertion has extended the indication of temporary hemiepiphysiodesis to patients younger than 10 years and across a wide variety of diagnosis including pathological physis, which were traditionally

  16. Geodetic evidence for passive control of a major Miocene tectonic boundary on the contemporary deformation field of Athens (Greece

    Directory of Open Access Journals (Sweden)

    Michael Foumelis

    2014-02-01

    Full Text Available A GPS-derived velocity field is presented from a dense geodetic network (~5km distance between stations established in the broader area of Athens. It shows significant local variations of strain rates across a major inactive tectonic boundary separating metamorphic and non-metamorphic geotectonic units. The southeastern part of Athens plain displays negligible deformation rates, whereas towards the northwestern part higher strain rates are observed, indicating the control of the inactive tectonic boundary on the contemporary deformation field of the region. These findings are in agreement with previous geological observations, however, due to the dense local GPS network it was fatherly possible to localize and quantify the effect of such a major inherited tectonic feature on the deformation pattern of the area.

  17. Water Release from Cold Serpentinized Forearc Mantle During Subduction Associated with Changes in Incoming Oceanic Plate Thermal Structure and Plate Boundary Kinematics: New Insights into Serpentinite Belts and Plate-Boundary Rheology

    Science.gov (United States)

    Kirby, Stephen

    2016-04-01

    Kirby, Wang, and Brocher (Earth Planets and Space, 2014) recently showed how the change in kinematics of the California margin from subduction motion to continental transform motion with the birth and growth of the San Andreas Fault System (SAFS) beginning at about 33 Ma BP likely led to a warming of the former forearc mantle and the release of water from serpentinized mantle by dehydration and a likely increase in fluid pressures along the SAFS. Such a mantle source of pressurized water gives insights into both the low sliding resistance for the SAFS and the mobilization and ascent of some serpentinized mantle peridotites through the crust. Thermal modeling by others has also shown that changes in the incoming plate age and subduction rate can also lead to warming of the forearc mantle during subduction. This development gives insights into the Mesozoic and Paleogene ages of emplacement of some, but not all, California serpentinites. Recent mineralogical and geochemical observations of serpentinite blocks in serpentinize mélange bodies in the San Francisco Bay Area (Uno and Kirby, 2014 AGU Meeting and Lewis and Kirby, 2015 AGU Meeting) suggest that these rocks sustained multiple stages of serpentinization that are broadly consistent with the model of Kirby et al. (2014). A new development comes from interpretation of investigations in the literature of localized late-stage silica-carbonate-water alteration of serpentinite bodies in California that this alteration occurred largely in Neogene time when the highest rates of water release from the former forearc mantle probably occurred. This presentation also suggests that the occurrence of serpentinite belts emplaced in Cenozoic time during changing plate-boundary kinematics, such as the Cenozoic closing of the Tethys Ocean bordering Eurasia by subduction and collision and arc reversal and decreasing convergence rates under the Greater Antilles and Colombia and New Guinea, may give insights into the serpentinite

  18. High resolution image of the Lithosphere-Asthenosphere Boundary of the subducting Nazca plate beneath northern Chile

    Science.gov (United States)

    Sodoudi, F.; Yuan, X.; Asch, G.; Kind, R.

    2010-12-01

    Results obtained from S and P receiver functions produced a clear image of the top and bottom of the subducting Nazca lithosphere beneath northern Chile. Using data from the teleseismic events recorded at 15 permanent IPOC (Integrated Plate boundary Observatory Chile) stations, we were able to obtain new constraints on the shape and thickness of the descending Nazca lithosphere. We observed the subducted crust of the Nazca plate at depths ranging from 40 km beneath the Coastal Cordillera down to 110 km beneath the Western Cordillera. We found significant along-strike variations in the geometry of the Nazca plate beneath northern Chile. On closer inspection, it appears that the oceanic Nazca plate is divided into two distinct segments as it descends beneath the continental South American plate. The transition from the relatively steeper and deeper slab to the north of 21° S to the flatter southern segment is shown reasonably clearly by our data. This feature could well be associated with variations in the curvature of the plate margin and the geometry of the Chile trench, which is mainly curved to the north of 21° S. We have also mapped the continental Moho of the South American plate at depths ranging between 60-70 km to the east of the Longitudinal Valley. Beneath the Coastal Cordillera, this boundary becomes invisible, probably due to the serpentinization of the forearc mantle wedge. The Lithosphere-Astheonsphere Boundary (LAB) of the subducted Nazca plate was clearly identified as a sharp boundary in the results obtained from the P and S receiver functions. The LAB lies at a depth of 80 km beneath the coastal area and dips from a depth of 100 km beneath the Coastal Cordillera to about 150 km underneath the Western Cordillera. High frequency PRF data enabled us to make confident estimates of the top and bottom of the Nazca lithosphere, which results in a lithospheric thickness of 57-60 km. In relation to the age of the Nazca plate, which is assumed to be ~ 50

  19. The northern Caribbean plate boundary in the Jamaica Passage: Structure and seismic stratigraphy

    Science.gov (United States)

    Corbeau, J.; Rolandone, F.; Leroy, S.; Mercier de Lépinay, B.; Meyer, B.; Ellouz-Zimmermann, N.; Momplaisir, R.

    2016-04-01

    Multibeam bathymetry data and multichannel seismic reflection profiles have been collected at the end of 2012 along the Enriquillo-Plantain-Garden Fault Zone (EPGFZ) in the Jamaica Passage, between Jamaica and Hispaniola. Analysis of the data set reveals the tectonic evolution and the stratigraphic complexity of the northern Caribbean boundary. Stratigraphic correlations with previous marine and on land studies are proposed to place the identified seismic sequences in their regional tectonic history. Two distinct crustal domains are interpreted. Typical stratigraphic sequences for the rifted blocks of the Eastern Cayman Trough margin are identified in five basins of the Jamaica Passage, highlighting the eastward limit of the Cayman Trough margin. These inherited basins are deformed and folded during a first phase of compression that could correspond to the regional tectonic rearrangement recorded in the early Miocene (about 20 Ma). A distinct crustal domain that we propose to relate to the Carib Beds (Caribbean typical reflectors A″, B″ and V) is identified in the southern part of the Jamaica Passage, indicating that the Caribbean Large Igneous Province could extend up to the extreme northeast part of the Lower Nicaragua Rise. The left-lateral EPGFZ currently cuts across two pre-existing basins, the Morant and Matley basins. During the activity of the EPGFZ, these basins are deformed and folded indicating a second phase of compression. In contrast, the Navassa basin, located in the middle of the Jamaica Passage, results from the strike-slip motion of the EPGFZ and is interpreted as an asymmetrical basin bordered by the EPGFZ only on its northern side.

  20. Effect of the severe plastic deformation temperature on the diffusion properties of the grain boundaries in ultrafine-grained metals

    Science.gov (United States)

    Chuvil'deev, V. N.; Myshlyaev, M. M.; Nokhrin, A. V.; Kopylov, V. I.; Lopatin, Yu. G.; Pirozhnikova, O. E.; Piskunov, A. V.; Semenycheva, A. V.; Bobrov, A. A.

    2017-05-01

    A model is proposed to explain the effect of the severe plastic deformation (SPD) temperature on the diffusion properties of the grain boundaries in ultrafine-grained (UFG) metals and alloys. It is shown that an increase in the SPD temperature in UFG metals leads to an increase in the activation energy of grainboundary diffusion from (3-5) k B T m, which corresponds to the diffusion parameters of nonequilibrium grain boundaries, to (8-10) k B T m, which corresponds to the diffusion parameters of equilibrium grain boundaries ( k B is the Boltzmann constant, T m is the melting temperature). The dependence of the activation energy of grain-boundary diffusion on the SPD temperature is found to be determined by the kinetics of the competing processes of defect accumulation at grain boundaries and the diffusion accommodation of defects.

  1. Determination of Euler parameters of Philippine Sea plate and the inferences

    Institute of Scientific and Technical Information of China (English)

    臧绍先; 陈起永; 宁杰远; 沈正康; 刘永刚

    2002-01-01

    Euler vectors of 12 plates, including Philippine Sea plate (PH), relative to a randomly fixed Pacific plate(PA) were determined by inverting the 1122 data from NUVEL-1 global plate motion model, earthquake slip vectors along Philippine Sea plate boundary, and GPS observed velocities. Euler vectors of Philippine Sea plate relative to adjacent plates are also gained. Our results are well consistent with observed data and can satisfy the geological and geophysical constraints along the Caroline(CR)-PH and PA-CR boundaries. Deformation of Philippine Sea plate is also discussed by using the plate motion Euler parameters.

  2. STRUCTURE OF THE LITHOSPHERE AND SEISMOTECTONIC DEFORMATIONS IN CONTACT ZONE OF LITHOSPHERIC PLATES IN THE SUMATRA ISLAND REGION

    Directory of Open Access Journals (Sweden)

    O. A. Kuchay

    2015-09-01

    Full Text Available The inversion seismic tomography algorithm (ITS was used to calculate 3D seismic anomalies models for velocities of P- and S-waves in the zone of the Sunda arc, Indonesia. In the area under study, strong earthquakes (M>4.8 are clustered in the zone of high P-wave velocities. Earthquake hypocenters are located in zones of both high and low velocity anomalies of S-waves. The giant Sumatra earthquake (December 26, 2004, Mw=9.0 ruptured the greatest fault length of any recorded earthquake, and the rupture started in the area wherein the sign of P-wave velo­city anomalies is abruptly changed. We calculated seismotectonic deformations (STD from data on mechanisms of 2227 earthquakes recorded from 1977 to 2013, and our calculations show that the STD component, that controls vertical extension of rocks, is most stable through all the depth levels. In the marginal regions at the western and eastern sides of the Sunda arc, the crustal areas (depths from 0 to 35 km are subject to deformations which sign is opposite to that of deformations in the central part. Besides, at depths from 70 to 150 km beneath the Sumatra earthquake epicentre area, the zone is subject to deformations which sign is opposite to that of deformations in the studied part of the Sunda arc. For earthquakes that may occur in the crust in the Sunda arc in the contact zone of the plates, maximum magnitudes depend on the direction of pressure imposed by the actively subducting plate, which is an additional criteria for determining the limit magnitude for the region under study. 

  3. Plate tectonics and offshore boundary delimitation: Tunisia-Libya case at the International Court of Justice

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, D.J.

    1983-03-01

    Advances in the technology for exploiting resources of the oceans, particularly recovery of hydrocarbons and minerals in deep water, is benefiting a growing number of nations. At the same time, however, economic and political pressures have induced concern and there is now a much increased emphasis on jurisdiction to divide the offshore areas between the 132 coastal nations. Negotiations affect research operations at sea and, in consequence, marine scientists have been made aware of offshore problems as highlighted by the Law of the Sea Treaty (UNCLOS III) and complications arising from the legal versus scientific definitions of continental shelves and margins. The first major offshore boundary case of international scope where plate tectonics has constituted a significant argument is the one recently brought before the International Court of Justice by Libya and Tunisia concerning the delimitation of their continental shelves. Of the two parties, Libya placed the greatest emphasis on this concept as a means to determine natural prolongation of its land territory into and under the sea. Tunisia contested Libya's use of the whole of the African continental landmass as a reference unit; in Tunisia's view, considerations of geography, geomorphology, and bathymetry are at least as relevant as are those of geology. In its landmark judgment (February 1982) - which almost certainly will have far-reaching consequences in future such boundary delimitation cases - the court pronounced that It is the outcome, not the evolution in the long-distant past, which is of importance, and that it is the present-day configuration of the coasts and sea bed which are the main factors to be considered, not geology.

  4. GPS and Geologic Deformation Rates Agree to Within Uncertainties in the Arabia-Africa- Eurasia Zone of Plate Interaction

    Science.gov (United States)

    Reilinger, R. E.; McClusky, S.

    2008-12-01

    Geodetically-derived motions for Arabia and Nubia relative to Eurasia agree within 1 standard deviation with plate rates estimated from geologic observations (McQuarrie et al., GRL, 2003) for the past 11 Myr for Nubia and greater than 25 Myr for Arabia. Furthermore, fault slip rates derived from an elastic block model constrained by GPS agree within uncertainties (about +/- 15 percent) with geologically determined, long-term slip rates in this complex area of plate interaction. Detailed geomorphological studies of the central North Anatolian fault (NAF) constrained by quantitative dating (Kozaci et a al., Geology, 2007) indicate slip rates that agree within uncertainties, but appear to be systematically lower than geodetic rates. While real rate changes of a few mm/yr cannot be ruled out at present, we note that geodetic inversions for coseismic fault slip on the NAF, and most other faults well constrained by geodetic observations, indicate larger slip at depth than at the surface. If this difference persists throughout the earthquake deformation cycle, it would account for the small difference in geodetic and geologic rates. Extrapolating present-day geodetic motions for Arabia relative to Nubia and Somalia to the time of initiation of Red Sea and Gulf of Aden extension indicates that Arabia separated from Nubia and Somalia simultaneously along the full extent of both rifts at about 25 Myr BP, consistent with independent geologic estimates for the style, and age of initiation of Red Sea extension (Omar and Steckler, 1995, Science). In addition, structural offsets across the Gulf of Suez (GoS) and Gulf of Aqaba (GoA) are consistent with a transfer of strain form the GoS to the GoA at around 12 Ma BP, roughly consistent with the age on initiation of the Dead Sea fault system. We further show that the apparent discrepancy between geodetic deformation of the Aegean (plate-like motion with low internal deformation), and geologic deformation (extensive crustal thinning

  5. The Potential Link Between High Angle Grain Boundary Morphology and Grain Boundary Deformation in a Nickel-Based Superalloy (Postprint)

    Science.gov (United States)

    2015-06-01

    B.V. All rights reserved.1. Introduction The creep deformation in polycrystalline nickel based super alloys is a heterogeneous process, the primary...annealing twins in G1 and G2 (TG1 and TG2 respectively). The d via the offset in hafnium oxide grid lines (white) deposited prior to deformation...titanium alloy , Acta Mater. 58 (16) (2010) 5511–5519 , URL 〈http://journals.ohiolink.edu/ejc/article.cgi? issn 13596454&issue v58i0016&article

  6. Chlorine isotope geochemistry of Icelandic thermal fluids: Implications for geothermal system behavior at divergent plate boundaries

    Science.gov (United States)

    Stefánsson, Andri; Barnes, Jaime D.

    2016-09-01

    The chlorine isotope composition of thermal fluids from Iceland were measured in order to evaluate the source of chlorine and possible chlorine isotope fractionation in geothermal systems at divergent plate boundaries. The geothermal systems studied have a wide range of reservoir temperatures from 40 to 437 °C and in-situ pH of 6.15 to 7.15. Chlorine concentrations range from 5.2 to 171 ppm and δ37 Cl values are -0.3 to + 2.1 ‰ (n = 38). The δ37 Cl values of the thermal fluids are interpreted to reflect the source of the chlorine in the fluids. Geothermal processes such as secondary mineral formation, aqueous and vapor speciation and boiling were found to have minimal effects on the δ37 Cl values. However, further work is needed on incorporation of Cl into secondary minerals and its effect on Cl isotope fractionation. Results of isotope geochemical modeling demonstrate that the range of δ37 Cl values documented in the natural thermal fluids can be explained by leaching of the basaltic rocks by meteoric source water under geothermal conditions. Magmatic gas partitioning may also contribute to the source of Cl in some cases. The range of δ37 Cl values of the fluids result mainly from the large range of δ37 Cl values observed for Icelandic basalts, which range from -0.6 to + 1.2 ‰.

  7. Numerical-perturbation technique for stability of flat-plate boundary layers with suction

    Science.gov (United States)

    Reed, H. L.; Nayfeh, A. H.

    1986-01-01

    A numerical-perturbation scheme is proposed for determining the stability of flows over plates with suction through a finite number of porous suction strips. The basic flow is calculated as the sum of the Blasius flow and closed-form linearized triple-deck solutions of the flow due to the strips. A perturbation technique is used to determine the increment a(ij) in the complex wavenumber at a given location x(j) due to the presence of a strip centered at x(i). The end result is a set of influence coefficients that can be used to determine the growth rates and amplification factors for any suction levels without repeating the calculations. The numerical-perturbation results are verified by comparison with interacting boundary layers for the case of six strips and the experimental data of Reynolds and Saric for single- and multiple-strip configurations. The influence coefficient form of the solution suggests a scheme for optimizing the strip configuration. The results show that one should concentrate the suction near branch I of the neutral stability curve, a conclusion verified by the experiments.

  8. HOT WIRE MEASUREMENT OF TURBULENT BOUNDARY LAYER ON A FILM COOLING PLATE WITH DIFFUSION HOLES

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This study experimentally investigated the film cooling flowfield of a single row of diffusion holes, from which the secondary air flow was injected into a turbulent boundary layer with zero pressure gradient on a flat plate. Circular-shaped holes were also tested as a basis for comparison. All the holes were inclined downstream at 35° with respect to the surface and the lateral spacing between the holes was 3 diameters of the hole. The mainstream velocity was maintained at 17 m/s and the Reynolds number based on the injection hole diameter was almost 11000. The density ratio of the jet to mainstream was 1.0, and the jet-to-mainstream velocity ratios M were 0.5 and 1.5. Normal-type and X-type hot wire anemometries were used to measure the streamwise mean velocity and its components, the normal and shear turbulent Reynolds stress components at the locations from the backward edge of the injection hole to 25 diameters downstream.

  9. The Baja California Borderland and the Neogene Evolution of the Pacific-North American Plate Boundary

    Science.gov (United States)

    Fletcher, J. M.; Eakins, B. W.

    2001-12-01

    New observational data on Neogene faulting in the borderland of Baja California places important constraints on tectonic models for the evolution of the Pacific-North American (P-NA) plate boundary and rifting in the Gulf of California. Neogene faults in the borderland range from strike slip to normal slip and accommodate integrated transtension. Most have east-facing escarpments and likely reactivate the former east-dipping accretionary complex. Numerous lines of evidence indicate that Neogene faults are still active and accomplish a significant component ( ~1-5 mm/yr) of Pacific-North American shearing. Quaternary volcanoes are found offshore and along the Pacific coastal margin, Quaternary marine terraces are warped and uplifted as high as 200 masl. Many of the offshore faults have fresh escarpments and cut Holocene sediments. Extensive arrays of Quaternary fault scarps are found throughout the coastal region and in Bahia Magdalena they are clearly associated with major faults that bound recently uplifted islands. A prominent band of seismicity follows the coast and eight earthquakes (Ms>5.0) were teleseismically recorded between 1973 and 1998. This evidence for active shearing indicates that the Baja microplate has not yet been completely transferred to the Pacific plate. The best lithologic correlation that can be used to define the total Neogene slip across the borderland faults is the offset between the Magdalena submarine fan and its Baja source terrane. The distal facies of the fan drilled during DSDP leg 63 is dominated by mudstone and siltstone that contain reworked Paleogene cocoliths derived from strata correlative with the Tepetate formation found throughout the borderland and fine-grained sandstone derived from a source terrane of granitoid basement. The Middle Miocene La Calera formation of the Cabo trough is one of many granitoid-clast syn-rift alluvial deposits that could form the continental counterpart of the submarine fan near the mouth of the

  10. Kr963660 -Low-Z Boundary of the Island of Deformation at N =60

    Science.gov (United States)

    Dudouet, J.; Lemasson, A.; Duchêne, G.; Rejmund, M.; Clément, E.; Michelagnoli, C.; Didierjean, F.; Korichi, A.; Maquart, G.; Stezowski, O.; Lizarazo, C.; Pérez-Vidal, R. M.; Andreoiu, C.; de Angelis, G.; Astier, A.; Delafosse, C.; Deloncle, I.; Dombradi, Z.; de France, G.; Gadea, A.; Gottardo, A.; Jacquot, B.; Jones, P.; Konstantinopoulos, T.; Kuti, I.; Le Blanc, F.; Lenzi, S. M.; Li, G.; Lozeva, R.; Million, B.; Napoli, D. R.; Navin, A.; Petrache, C. M.; Pietralla, N.; Ralet, D.; Ramdhane, M.; Redon, N.; Schmitt, C.; Sohler, D.; Verney, D.; Barrientos, D.; Birkenbach, B.; Burrows, I.; Charles, L.; Collado, J.; Cullen, D. M.; Désesquelles, P.; Domingo Pardo, C.; González, V.; Harkness-Brennan, L.; Hess, H.; Judson, D. S.; Karolak, M.; Korten, W.; Labiche, M.; Ljungvall, J.; Menegazzo, R.; Mengoni, D.; Pullia, A.; Recchia, F.; Reiter, P.; Salsac, M. D.; Sanchis, E.; Theisen, Ch.; Valiente-Dobón, J. J.; Zielińska, M.

    2017-04-01

    Prompt γ -ray spectroscopy of the neutron-rich 96Kr, produced in transfer- and fusion-induced fission reactions, has been performed using the combination of the Advanced Gamma Tracking Array and the VAMOS ++ spectrometer. A second excited state, assigned to Jπ=4+, is observed for the first time, and a previously reported level energy of the first 2+ excited state is confirmed. The measured energy ratio R4 /2=E (4+)/E (2+)=2.12 (1 ) indicates that this nucleus does not show a well-developed collectivity contrary to that seen in heavier N =60 isotones. This new measurement highlights an abrupt transition of the degree of collectivity as a function of the proton number at Z =36 , of similar amplitude to that observed at N =60 at higher Z values. A possible reason for this abrupt transition could be related to the insufficient proton excitations in the g9 /2, d5 /2, and s1 /2 orbitals to generate strong quadrupole correlations or to the coexistence of competing different shapes. An unexpected continuous decrease of R4 /2 as a function of the neutron number up to N =60 is also evidenced. This measurement establishes the Kr isotopic chain as the low-Z boundary of the island of deformation for N =60 isotones. A comparison with available theoretical predictions using different beyond mean-field approaches shows that these models fail to reproduce the abrupt transitions at N =60 and Z =36 .

  11. Practice of Improving Roll Deformation Theory in Strip Rolling Process Based on Boundary Integral Equation Method

    Science.gov (United States)

    Yuan, Zhengwen; Xiao, Hong; Xie, Hongbiao

    2014-02-01

    Precise strip-shape control theory is significant to improve rolled strip quality, and roll flattening theory is a primary part of the strip-shape theory. To improve the accuracy of roll flattening calculation based on semi-infinite body model, a new and more accurate roll flattening model is proposed in this paper, which is derived based on boundary integral equation method. The displacement fields of the finite length semi-infinite body on left and right sides are simulated by using finite element method (FEM) and displacement decay functions on left and right sides are established. Based on the new roll flattening model, a new 4Hi mill deformation model is established and verified by FEM. The new model is compared with Foppl formula and semi-infinite body model in different strip width, roll shifting value and bending force. The results show that the pressure and flattening between rolls calculated by the new model are more precise than other two models, especially near the two roll barrel edges.

  12. Using EarthScope Construction of the Plate Boundary Observatory to Provide Locally Based Experiential Education and Outreach

    Science.gov (United States)

    Jackson, M.; Eriksson, S.; Barbour, K.; Venator, S.; Mencin, D.; Prescott, W.

    2006-12-01

    EarthScope is an NSF-funded, national science initiative to explore the structure and evolution of the North American continent and to understand the physical processes controlling earthquakes and volcanoes. This large-scale experiment provides locally based opportunities for education and outreach which engage students at various levels and the public. UNAVCO is responsible for the Plate Boundary Observatory (PBO) component of EarthScope. PBO includes the installation and operations and maintenance of large networks of Global Positioning Satellite (GPS), strainmeter, seismometer, and tiltmeter instruments and the acquisition of satellite radar imagery, all of which will be used to measure and map the smallest movements across faults, the magma movement inside active volcanoes and the very wide areas of deformation associated with plate tectonic motion. UNAVCO, through its own education and outreach activities and in collaboration with the EarthScope E&O Program, uses the PBO construction activities to increase the understanding and public appreciation of geodynamics, earth deformation processes, and their relevance to society. These include programs for public outreach via various media, events associated with local installations, a program to employ students in the construction of PBO, and development of curricular materials by use in local schools associated with the EarthScope geographic areas of focus. PBO provides information to the media to serve the needs of various groups and localities, including interpretive centers at national parks and forests, such as Mt. St. Helens. UNAVCO staff contributed to a television special with the Spanish language network Univision Aquí y Ahora program focused on the San Andreas Fault and volcanoes in Alaska. PBO participated in an Education Day at the Pathfinder Ranch Science and Outdoor Education School in Mountain Center, California. Pathfinder Ranch hosts two of the eight EarthScope borehole strainmeters in the Anza

  13. Localization of ductile deformation in lithosphere and rocks: the role of grain boundary sliding

    Science.gov (United States)

    Dimanov, Alexandre; Rahanel, Jean; Bornert, Michel; Bourcier, Mathieu; Gaye, Ag; Heripre, Eva; Ludwig, Wolfgang

    2017-04-01

    Ductile strain of the lithosphere localizes in multi-scale shear zones, ranging from km to mm scales. The resulting mylonites/ultramylonites present microstructural signatures of several concomitant deformation mechanisms. Besides cataclastic features, crystal plasticity dominates in volume, but grain boundary sliding and diffusive/solution mass transport act along interfaces. Considering solely the inherited natural microstructures does not make clear the chronology of appearance and the interactions between these mechanisms. Therefore, inference of the overall mylonitic rheology seems illusory. We have therefore realized over the last decade a systematic rheological characterization of the high temperature flow of various synthetic anorthite - diopside mixtures. The data clearly suggest Newtonian type of rheology as best adapted to the materials representative of the lower crust mylonites. However, the post mortem microstructures undoubtedly evidenced the coexistence of both crystal plasticity and grain boundary sliding processes. Yet, the specific roles of each mechanism in the localization process remained unclear. In order to clarify these aspects we realized a multi-scale micromechanical in situ investigation of the ductile deformation of synthetic rock-salt. The mechanical tests were combined with in-situ optical microscopy, scanning electron microscopy and X-ray tomography (MCT). Digital image correlation (DIC) techniques allowed for measurements and characterization of the multi-scale organization of 2D and 3D full strain fields. Macroscopic and mesoscopic shear bands appear at the sample and microstructure scales, respectively. DIC evidenced the development of discrete slip bands within individual grains, and hence of dominant crystal plasticity. Combination of DIC and EBSD allowed for identification of active slip systems. Conversely, DIC allowed for the identification and the precise quantification of minor activity (< 5% contribution) of grain boundary

  14. Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria-Europe plate boundary (Western Alps, Calabria, Corsica)

    Science.gov (United States)

    Malusà, Marco G.; Faccenna, Claudio; Baldwin, Suzanne L.; Fitzgerald, Paul G.; Rossetti, Federico; Balestrieri, Maria Laura; Danišík, Martin; Ellero, Alessandro; Ottria, Giuseppe; Piromallo, Claudia

    2015-06-01

    Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary.

  15. Control of deflection deformation of plate-shape castings in solidification

    Institute of Scientific and Technical Information of China (English)

    郑贤淑; 金英达

    2003-01-01

    The deformation mechanism during the solidification was analyzed based on the experimental results ofthe castings. An approximate quadratic differential equation and its discrete model of calculation deflection were pro-posed. The model indicates that the key factors leading to the deflection deformation are the thermal bending mo-ment M and the flexural rigidity E.J. The smaller the former and the larger the latter is, the smaller the deflectiondeformation will be. The experiments are carried out at various technical conditions, and their results appear good a-greement with calculation ones. A method was proposed to predict and control the casting deformation.

  16. Large vertical motions and basin evolution in the Outer Continental Borderland off Southern California associated with plate boundary development and continental rifting

    Science.gov (United States)

    Nicholson, C.; Sorlien, C. C.; Schindler, C. S.; De Hoogh, G.

    2011-12-01

    The Continental Borderland offshore southern California occupies a strategic position along the continental margin. It was the locus of ~75% of Pacific-North America displacement history, it helped accommodate the large-scale (>90°) tectonic rotation of the Western Transverse Ranges province, and is still accommodating potentially 20% of PAC-NAM plate motion today. As such, it represents an ideal natural laboratory to investigate plate boundary evolution and basin development associated with transform initiation, oblique continental rifting, transrotation and transpression. We have been using newly released grids of high-quality industry multichannel seismic (MCS) reflection data, combined with multibeam bathymetry and offshore well data to map and construct digital 3D fault surfaces and stratigraphic reference horizons over large parts of the Outer Continental Borderland. These 3D surfaces of structure and stratigraphy can be used to better understand and evaluate regional patterns of uplift, subsidence, fault interaction and other aspects of plate boundary deformation. In the northern Outer Borderland, mapping in Santa Cruz basin, and across both Santa Rosa and Santa Cruz-Catalina ridges reveals a pattern of interacting high-and low-angle faults, fault reactivation, basin subsidence, folding, and basin inversion. Subsidence since early-Miocene time is significant (up to 4 km) and is much larger than predicted by simple thermal cooling models of continental rifting. This requires additional tectonic components to drive this regional subsidence and subsequent basin inversion. Farther south, a more en echelon pattern of ridges and basins suggests a distributed component of right-lateral shear also contributed to much of the modern Borderland seafloor topography, including major Borderland basins. Vertical motions of uplift and subsidence can be estimated from a prominent early-Miocene unconformity that likely represents a regional, paleo-horizontal, near

  17. SEM observation of grain boundary structures in quartz-iron oxide rocks deformed at intermediate metamorphic conditions

    Directory of Open Access Journals (Sweden)

    Leonardo Lagoeiro

    2011-09-01

    Full Text Available Several studies have demonstrated the effect of a second phase on the distribution of fluid phase and dissolution of quartz grains. However, as most observations came from aggregates deformed under hydrostatic stress conditions and mica-bearing quartz rocks, 3-D distribution of pores on quartz-quartz (QQB and quartz-hematite boundaries (QHB has been studied. Several fracture surfaces oriented according to finite strain ellipsoid were analyzed. The pore distribution characterizes the porosity and grain shape as highly anisotropic, which results from the nature and orientation of boundaries. QHB have physical/chemical properties very different from QQB, once the hematite plates have strong effect on wetting behavior of fluid, likewise micas in quartzites. They are pore-free flat surfaces, normal to compression direction, suggesting that they were once wetted with a continuous fluid film acting as faster diffusion pathway. At QQB, the pores are faceted, isolated, close to its edges reflecting the crystallographic control and an interconnected network of fluid along grain junctions. The QQB facing the extension direction are sites of fluid concentration. As consequence, the anisotropic dissolution and grain growth were responsible for the formation of hematite plates and tabular quartz grains significantly contributing for the generation of the foliation observed in the studied rocks.Muitos estudos têm demonstrado o efeito de uma segunda fase sobre a distribuição de fase fluida e dissolução de grãos de quartzo. Entretanto, como a maioria das observações vêm de agregados deformados sob condições de tensão hidrostática e em rochas quartzosas ricas em mica, a distribuição 3D de poros e bordas quartzo-quartzo (BQQ e quartzo-hematita (BQH tem sido estudada. Várias superfícies de fraturas orientadas segundo o elipsóide de deformação finita foram analisadas. A distribuição dos poros caracteriza a porosidade e a forma dos grãos como

  18. Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary

    Science.gov (United States)

    Gonçalves da Silva, Hugo; Bezzeghoud, Mourad; Biagi, Pier; Namorado Rosa, Rui; Salgueiro da Silva, Manuel; Caldeira, Bento; Heitor Reis, Artur; Borges, José Fernando; Tlemçani, Mouhaydine; Manso, Marco

    2010-05-01

    This paper presents a future research plan that aims to monitor Seismo-electromagnetic (SEM) phenomena in the western part of the Eurasia-Nubia plate boundary (WENP). This region has a significant tectonic activity [1] combined with relatively low electromagnetic noise levels and for that reason presents the possibility to perform high quality SEM measurements. Further, it is known that low-frequency [ultra (ULF), very (VLF), and low-frequencies (LF)] electromagnetic (EM) waves produce more convincing earthquake precursors (compared to higher frequencies) because of less contamination, large skin depth, and low attenuation [2]. Thus, two SEM effects will be considered: ULF electromagnetic field emissions [3], and VLF/LF radio broadcastings [4]. With respect to the ULF measurements, as a start, three ULF sensors are planned to be installed in the South of Iberian Peninsula supported by the existing networks of seismic research stations. Subsequent development of this initial plan could result in the implementation of a lager ULF monitoring network not only in the Iberian Peninsula, but also in the rest of Europe. Possible integration in the SEGMA array is now under consideration. Another perspective is to use a portable station to track seismic events. Regarding the VLF/LF radio broadcastings, a receiver is planned to be mounted in University of Évora. Radio signals from up to 10 transmitters (in these bands) of interest to study the seismic activity in the WENP region will be monitored. Actually, the radio path from the transmitter to the receiver should cross the epicentral area, therefore two possible transmitters are the ones installed in Monaco (France) and Sicily (Italy). Furthermore, the system will integrate the INFREP network and in this context it will not be restricted to WENP region. With the development of these research plans we aim to collect novel SEM data emerging from the seismic activity in the WENP region. We expect to address the time

  19. Shape memory alloy actuation effect on subsonic static aeroelastic deformation of composite cantilever plate

    Science.gov (United States)

    Hussein, A. M. H.; Majid, D. L. Abdul; Abdullah, E. J.

    2016-10-01

    Shape memory alloy (SMA) is one of the smart materials that have unique properties and used recently in several aerospace applications. SMAs are metallic alloys that can recover permanent strains when they are heated above a certain temperature. In this study, the effects of SMA actuation on the composite plate under subsonic aeroelastic conditions are examined. The wind tunnel test is carried out for two configurations of a cantilever shape memory alloy composite plate with a single SMA wire fixed eccentrically. Strain gage data for both bending and torsional strain are recorded and demonstrated during the aeroelastic test for active and non-active SMA wire in two locations. The cyclic actuation of the SMA wire embedded inside the composite plate is also investigated during the aeroelastic test. The results show reduction in both bending and torsional strain of the composite plate after activation of the SMA wire during the wind tunnel test.

  20. Lasting mantle scars lead to perennial plate tectonics.

    Science.gov (United States)

    Heron, Philip J; Pysklywec, Russell N; Stephenson, Randell

    2016-06-10

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a 'perennial' phenomenon.

  1. Lasting mantle scars lead to perennial plate tectonics

    Science.gov (United States)

    Heron, Philip J.; Pysklywec, Russell N.; Stephenson, Randell

    2016-06-01

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a `perennial' phenomenon.

  2. Study of Transition from Laminar to Turbulent Boundary Layer on a Tilted Flat Plate Using Heat Transfer Measurements

    Institute of Scientific and Technical Information of China (English)

    E.Sanz; C.Nicot; R.Point; F.Plaza

    2007-01-01

    The boundary layer transition over a flat tilted plate has been studied by means of heat transfer measurements. A heat flux sensor has been developed, in order to measure the efficiency of convective heat transfer for various types of surfaces or flows. Its operation at constant temperature allows direct and fast measurements of heat flux. The present paper reports the development of the sensor and presents its application to the study of transition in a boundary layer depending on the angle of incidence of the external flow. An exponential relationship between critical Reynolds number and pressure gradient parameter has been found.

  3. From arc-continent collision to continuous convergence, clues from Paleogene conglomerates along the southern Caribbean-South America plate boundary

    Science.gov (United States)

    Cardona, A.; Montes, C.; Ayala, C.; Bustamante, C.; Hoyos, N.; Montenegro, O.; Ojeda, C.; Niño, H.; Ramirez, V.; Valencia, V.; Rincón, D.; Vervoort, J.; Zapata, S.

    2012-12-01

    A Paleogene conglomeratic-sandy succession preserves the complex record of arc-continent collision, orogen collapse and basin opening, followed by inversion related to renewed oblique convergence. This record is unique because both arc and continental margin are now severely fragmented and only partially exposed along the southern Caribbean-South American boundary in northern Colombia. We studied these clastic sequences in the San Jacinto deformed belt using an integrated provenance study that includes conglomerate clast counting, geochemistry and U-Pb and Hf isotopic analysis in magmatic clasts, together with sandstone petrography, heavy mineral analysis and detrital zircon U-Pb geochronology. The record of events extracted from these coarse clastic rocks includes the formation and approach of an allochthonous Upper Cretaceous intra-oceanic arc active from 88 Ma until 73 Ma. This arc collides against the upper Paleozoic to Triassic continental margin after 73 Ma, but before late Paleocene times. Poorly exposed remnants of serpentinized peridotites and middle pressure metamorphic detritus are related to closure of an intervening oceanic basin between the continent and the colliding arc. This orogen was emerged in late Maastrichtian-early Paleocene, and then collapsed as recorded by the thick upper Paleocene and younger succession of the San Jacinto deformed belt where the coarse clastics, subject of this study, are exposed. Orogenic collapse may have been the result of subduction zone flip, with incipient subduction of the buoyant Caribbean Plate under South America.

  4. A strongly-coupled immersed-boundary formulation for thin deforming surfaces, with application to elastic beams

    CERN Document Server

    Goza, Andres

    2016-01-01

    We present a strongly-coupled immersed-boundary method for flow-structure interaction problems involving thin deforming bodies. The method is stable for arbitrary choices of solid-to-fluid mass ratios and for large body motions. As with many strongly-coupled immersed-boundary methods, our method requires the solution of a nonlinear algebraic system at each time step. The system is solved through iteration, where the iterates are obtained by linearizing the system and performing a block LU factorization. This restricts all iterations to small-dimensional subsystems that scale with the number of discretization points on the immersed surface, rather than on the entire flow domain. Moreover, the iteration procedure we propose does not involve heuristic regularization parameters, and has converged in a small number of iterations for all problems we have considered. We derive our method for general deforming surfaces, and verify the method with two-dimensional test problems of geometrically nonlinear beams undergoi...

  5. Refined Views of Strike-slip Fault Zones, Seismicity, and State of Stress Associated With the Pacific-North America Plate Boundary in Southern California

    Science.gov (United States)

    Hauksson, E.; Nicholson, C.; Shaw, J. H.; Plesch, A.; Shearer, P. M.; Sandwell, D. T.; Yang, W.

    2013-12-01

    The mostly strike-slip plate boundary in southern California is expressed as a system of late Quaternary faults or principal slip zones (PSZs), with numerous adjacent smaller slip surfaces. It is complex, even after large cumulative displacements, and consists of major fault systems with multi-stranded, non-planar fault geometry, including some in close proximity to each other. There are also secondary cross faults and low-angle detachments that interact with the PSZs accommodating main plate boundary motion. The loading of plate-tectonic strain causes the largest earthquakes along PSZs, moderate-sized events in their immediate vicinity, and small earthquakes across the whole region. We apply relocated earthquake and refined focal mechanism (1981-2013) catalogs, as well as other geophysical datasets to provide refined views of the 3D fault geometry of these active fault systems. To determine properties of individual fault zones, we measure the Euclidian distance from every hypocenter to the nearest PSZ. In addition, we assign crustal geophysical parameters such as heat flow value and shear or dilatation strain rates to each epicenter. We investigate seismogenic thickness and fault zone width as well as earthquake source processes. We find that the seismicity rate is a function of location, with the rate dying off exponentially with distance from the PSZ. About 80% of small earthquakes are located within 5 km of a PSZ. For small earthquakes, stress drops increase in size with distance away from the PSZs. The magnitude distribution near the PSZs suggests that large earthquakes are more common close to PSZs, and they are more likely to occur at greater depth than small earthquakes. In contrast, small quakes can occur at any geographical location. An optimal combination of heat flow and strain rate is required to concentrate the strain along rheologically weak fault zones, which accommodate the crustal deformation processes, causing seismicity. The regional trend of

  6. Update on Plate Boundary Observatory (PBO) Activities in the PNW Region

    Science.gov (United States)

    Austin, K. E.; Fengler, K.; Doelger, S.

    2007-12-01

    The Plate Boundary Observatory (PBO), which is part of the larger NSF-funded EarthScope project, is nearing the end of year 3 of the installation phase of 852 continuously operating GPS stations in the Western United States. The Pacific Northwest (PNW) region will install 134 continuous GPS stations by the end of September 2008. The sites are distributed along the fore and back-arc of the Cascadia Subduction Zone and at Mt. St. Helens. At the end of September 2007, the PNW region will be several stations short of its installation goal of 110 GPS stations, mostly due to an unusually early and high danger wildfire season. The scientific priority during this past year was to concentrate installations in the Oregon back arc region, the Southwest Oregon fore arc region and the Idaho panhandle. In the last year UNAVCO has added 10 stations to the Pacific Northwest region, raising the number of stations from 124 to 134. The majority of these stations are located within the fore and back arc regions of Southern Oregon. In addition the UNAVCO installed its first building mounted site within a difficult area along the Southwest Oregon coast. UNAVCO will install its remaining 24 new continuous GPS stations in the Pacific Northwest in year 5. The remaining stations are distributed throughout the region, and comprise a mix of standard monuments, and strainmeter collocations. Our goal is to have all stations installed by August 31 2008. Reconnaissance work for all of the GPS sites have been completed, and have had permits submitted.

  7. EarthScope Plate Boundary Observatory, Southwest Region - Communications, Challenges, and Cooperation

    Science.gov (United States)

    Turner, R. C.; Mann, D.; Walls, C. P.; Basset, A.; Lawrence, S.; Berglund, H. T.

    2015-12-01

    The Southwest Region of the EarthScope Plate Boundary Observatory is engaged in efforts to expand capabilities and renovate the network. These efforts include GNSS hardware modernization (in cooperation with state and local agencies), communications upgrades that improve data throughput and decrease recurring costs, co-location of prototype instruments for use in earthquake early warning, and working to ensure consistent high-quality data in the face of radio spectrum encroachment.The Global Positioning System (GPS) is but one of a growing number of global navigation satellite systems (GNSS) with the potential to improve geodetic observations. In addition to strategic deployment of GNSS-capable hardware, the Southwest region is currently developing an agreement with Caltrans to augment the network with GNSS systems at about a dozen stations. The upgrades will consist of a number of Caltrans-provided GLONASS-ready receivers and project is scheduled for completion by early 2016.The Southwest Region has continued to upgrade and build new radio networks to improve dependability, monitoring, and data download rates (including transfers of high-rate data). Here, we highlight one such network near Hollister, CA, which eliminated several cellular modems and improved reliability.UNAVCO and Scripps have been working in collaboration to augment a subset of GPS stations with low-cost strong-motion sensors for use in Earthquake Early Warning systems. To date, 21 PBO stations have been upgraded with MEMS accelerometers along the San Andreas and San Jacinto Faults in Northern and Southern California, 15 of which stream data to UNAVCO in real time.As the use of the radio frequency spectrum increases, PBO faces more radio frequency interference (RFI) in our data communications networks; in addition, RFI issues are beginning to impact GNSS data collection. Here we report on a PBO site suspected of suffering from RFI and discuss briefly mitigation efforts to minimize these effects.

  8. Monitoring the northern Chile megathrust with the Integrated Plate boundary Observatory Chile (IPOC)

    Science.gov (United States)

    Schurr, Bernd; Asch, Günter; Cailleau, Beatrice; Diaz, Guillermo Chong; Barrientos, Sergio; Vilotte, Jean-Pierre; Oncken, Onno

    2010-05-01

    thousand aftershocks during the following week using waveform cross-correlation and the double-difference algorithm. Aftershocks reveal that rupture during this earthquake was confined to the deeper part (35 - 55 km depth) of the seismogenic coupling zone, except near the Mejillones peninsula that marks rupture termination in the south. Here earthquake activity reaches to depths of 20 km and even shallower, possibly indicating upper plate activation. The sequence also features an M 6.8 earthquake that broke the oceanic slab on an almost vertical plane at the down-dip end of the megathrust rupture. Confrontation with the aftershock distribution of the 1995 M 8.0 Antofagasta earthquake on the adjoining southern segment reveals an intriguing mirror symmetry with an axis crossing the Mejillones peninsula, emphasizing the penisula's significance as a segment boundary. Since then activity inside the remaining seismic gap to the north picked up with three earthquakes exceeding magnitude 6, maybe heralding the next great rupture.

  9. Double-diffusive natural convective boundary-layer flow of a nano-fluid past a vertical plate

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, A.V. [Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, Raleigh, NC 27695-7910 (United States); Nield, D.A. [Department of Engineering Science, University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand)

    2011-05-15

    The double-diffusive natural convective boundary-layer flow of a nano-fluid past a vertical plate is studied analytically. The model used for the binary nano-fluid incorporates the effects of Brownian motion and thermophoresis. In addition the thermal energy equations include regular diffusion and cross-diffusion terms. A similarity solution is presented. Numerical calculations were performed in order to obtain correlation formulas giving the reduced Nusselt number as a function of the various relevant parameters. (authors)

  10. UNAVCO Enhanced data products for the EarthScope Plate Boundary Observatory, COCONet, and other regional networks

    Science.gov (United States)

    Puskas, C. M.; Phillips, D. A.; Mattioli, G. S.; Meertens, C. M.; Herring, T.; Murray, M. H.; Melbourne, T. I.; Boler, F. M.; Blewitt, G.; Larson, K. M.; Feaux, K.; Braun, J. J.; Small, E. E.

    2012-12-01

    As part of an initiative to improve data services and support new research in the geodetic community, UNAVCO and its partners are expanding our supported data products and releasing new visualization tools. The enhanced data products, primarily associated with the UNAVCO-managed EarthScope Plate Boundary Observatory (PBO) and COCONet project, have open access and are archived at UNAVCO. UNAVCO manages community data services for a range of geodetic systems: GPS, borehole strainmeters, laser strainmeters, tiltmeters, pore pressure sensors, and geodetic imaging (InSAR, LIDAR, and terrestrial laser scanning). As part of the expansion, UNAVCO will incorporate data products submitted or downloaded from outside agencies. We focus here on the GPS products, which will include improved geodetic coverage in the western U.S. and expanded coverage in North America, access to new station quality parameters, information on site hydrologic conditions, and hydrologic loading models. Existing, open-access GPS stations from other networks are being incorporated into current 1112-station PBO processing stream to obtain station position time series and velocities for an additional 500+ stations. The primary data sources will be the Southern California Integrated GPS Network (SCIGN), the Scripps Orbit and Permanent Array Center (SOPAC), and the National Geodetic Survey's Continuously Operating Reference (NGS CORS) network. These additional stations will comprise a backbone network across continental North America to better resolve the surface velocity field in central and eastern U.S. and Canada, regions not presently covered by PBO. The expanded geographic coverage will address possible tectonic signals on a continental scale and will improve resolution of intraplate seismic zones and glacial-isostatic adjustments. The large data set will also have non-tectonic applications such as hydrologic studies, reference frame determination, and atmospheric studies. Station quality parameters

  11. Constraints on fault slip rates of the southern California plate boundary from GPS velocity and stress inversions

    Science.gov (United States)

    Becker, T.W.; Hardebeck, J.L.; Anderson, G.

    2005-01-01

    We use Global Positioning System (GPS) velocities and stress orientations inferred from seismicity to invert for the distribution of slip on faults in the southern California plate-boundary region. Of particular interest is how long-term slip rates are partitioned between the Indio segment of the San Andreas fault (SAF), the San Jacinto fault (SJF) and the San Bernardino segment of the SAE We use two new sets of constraints to address this problem. The first is geodetic velocities from the Southern California Earthquake Center's (SCEC) Crustal Motion Map (version 3 by Shen et al.), which includes significantly more data than previous models. The second is a regional model of stress-field orientations at seismogenic depths, as determined from earthquake focal mechanisms. While GPS data have been used in similar studies before, this is the first application of stress-field observations to this problem. We construct a simplified model of the southern California fault system, and estimate the interseismic surface velocities using a backslip approach with purely elastic strain accumulation, following Meade et al. In addition, we model the stress orientations at seismogenic depths, assuming that crustal stress results from the loading of active faults. The geodetically derived stressing rates are found to be aligned with the stress orientations from seismicity. We therefore proceed to invert simultaneously GPS and stress observations for slip rates of the faults in our network. We find that the regional patterns of crustal deformation as imaged by both data sets can be explained by our model, and that joint inversions lead to better constrained slip rates. In our preferred model, the SJF accommodates ???15 mm yr-1 and the Indio segment of the SAF ???23 mm yr-1 of right-lateral motion, accompanied by a low slip rate on the San Bernardino segment of the SAF 'Anomalous' fault segments such as around the 1992 Mw = 7.3 Landers surface rupture can be detected. There, observed

  12. Boundary value analysis of parallel plate capacitors%平板电容器的边值分析

    Institute of Scientific and Technical Information of China (English)

    赵琳; 蒋泽

    2004-01-01

    将平板电容器电容的计算作为典型的场边值问题进行处理,从而得到了可适用于对具有任意极板半径与其间隔之比的平板电容器电容的分析求解关系,数值计算结果与有关理论分析的高度一致性,表明了所建立的分析模型的有效性。%By taking the computation of capacitance of a parallel plate capacitor as a boundary value problem.a formula for the computation with any ratio of the plate separation to the radius of the plate is presented.The model shows effectiveness by the good agreement between the analytical and the numerical results.

  13. DNS of heat transfer in transitional, accelerated boundary layer flow over a flat plate affected by free-stream fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Wissink, Jan G. [School of Engineering and Design, Howell Building, Brunel University, Uxbridge UB8 3PH (United Kingdom)], E-mail: jan.wissink@brunel.ac.uk; Rodi, Wolfgang [Institute for Hydromechanics, University of Karlsruhe, Kaiserstr. 12, D-76128 Karlsruhe (Germany)

    2009-10-15

    Direct numerical simulations (DNS) of flow over and heat transfer from a flat plate affected by free-stream fluctuations were performed. A contoured upper wall was employed to generate a favourable streamwise pressure gradient along a large portion of the flat plate. The free-stream fluctuations originated from a separate LES of isotropic turbulence in a box. In the laminar portions of the accelerating boundary layer flow the formation of streaks was observed to induce an increase in heat transfer by the exchange of hot fluid near the surface of the plate and cold fluid from the free-stream. In the regions where the streamwise pressure gradient was only mildly favourable, intermittent turbulent spots were detected which relaminarised downstream as the streamwise pressure gradient became stronger. The relaminarisation of the turbulent spots was reflected by a slight decrease in the friction coefficient, which converged to its laminar value in the region where the streamwise pressure gradient was strongest.

  14. Unsteady heat-flux measurements of second-mode instability waves in a hypersonic flat-plate boundary layer

    Science.gov (United States)

    Kegerise, Michael A.; Rufer, Shann J.

    2016-08-01

    In this paper, we report on the application of the atomic layer thermopile (ALTP) heat-flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat-plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors, and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are consistent with data previously reported in the literature. Heat flux time series, and the Morlet wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was used to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

  15. Applications of a General Finite-Difference Method for Calculating Bending Deformations of Solid Plates

    Science.gov (United States)

    Walton, William C., Jr.

    1960-01-01

    This paper reports the findings of an investigation of a finite - difference method directly applicable to calculating static or simple harmonic flexures of solid plates and potentially useful in other problems of structural analysis. The method, which was proposed in doctoral thesis by John C. Houbolt, is based on linear theory and incorporates the principle of minimum potential energy. Full realization of its advantages requires use of high-speed computing equipment. After a review of Houbolt's method, results of some applications are presented and discussed. The applications consisted of calculations of the natural modes and frequencies of several uniform-thickness cantilever plates and, as a special case of interest, calculations of the modes and frequencies of the uniform free-free beam. Computed frequencies and nodal patterns for the first five or six modes of each plate are compared with existing experiments, and those for one plate are compared with another approximate theory. Beam computations are compared with exact theory. On the basis of the comparisons it is concluded that the method is accurate and general in predicting plate flexures, and additional applications are suggested. An appendix is devoted t o computing procedures which evolved in the progress of the applications and which facilitate use of the method in conjunction with high-speed computing equipment.

  16. Nonlinear dynamics of angle-ply composite laminated thin plate with third-order shear deformation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An asymptotic perturbation method is presented based on the Fourier expansion and temporal rescaling to investigate the nonlinear oscillations and chaotic dynamics of a simply supported angle-ply composite laminated rectangular thin plate with parametric and external excitations.According to the Reddy’s third-order plate theory,the governing equations of motion for the angle-ply composite laminated rectangular thin plate are derived by using the Hamilton’s principle.Then,the Galerkin procedure is applied to the partial differential governing equation to obtain a two-degrees-of-freedom nonlinear system including the quadratic and cubic nonlinear terms.Such equations are utilized to deal with the resonant case of 1:1 internal resonance and primary parametric resonance-1/2 subharmonic resonance.Furthermore,the stability analysis is given for the steady-state solutions of the averaged equation.Based on the averaged equation obtained by the asymptotic perturbation method,the phase portrait and power spectrum are used to analyze the multi-pulse chaotic motions of the angle-ply composite laminated rectangular thin plate.Under certain conditions the various chaotic motions of the angle-ply composite laminated rectangular thin plate are found.

  17. Triassic to Cenozoic multi-stage intra-plate deformation focused near the Bogd Fault system, Gobi Altai, Mongolia

    Institute of Scientific and Technical Information of China (English)

    Douwe J.J. van Hinsbergen; Dickson Cunningham; Gijsbert B. Straathof; Morgan Ganerød; Bart W.H. Hendriks; Arjan H. Dijkstra

    2015-01-01

    The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the mid-Mesozoic, yet has experienced episodic phases of deformation since that time. In this paper, we docu-ment field evidence to characterize and date the intra-plate tectonic history of the Gobi Altai region from the Triassic to the present. To this end, we provide detailed mapping of the structure and stratigraphy of the eastern flanks of Mt. Ih Bogd that contains the widest variety of rock-time units in the area. We carry out geochronological analysis of basaltic lavas and basement granite in the area. We demonstrate that a crystalline basement with a 502 ? 8 Ma granitoid (U/Pb) underwent two phases of basin formation in the Mesozoic, which we date with new 40Ar/39Ar lava ages of 218.5 ? 1.5, 123.2 ? 0.7 and 124.8 ? 1.2 Ma, respectively. Both phases are linked to deposition of fluvio-lacustrine sediments and trap-like basaltic volcanics, with cumulative thicknesses of 1000e1500 m. Both basins were likely north-facing half-gra-bens that developed under wNeS extension, but were subsequently overthrusted by Paleozoic and older crystalline basement during a less well constrained, but likely mid-Cretaceous phase of NeS shortening and basin inversion. Our results are consistent with recent seismic imaging of rift basins w100 km to the NE of the study area where a similar history was reconstructed. The multiple phases of intra-plate deformation appear to have parallel structural trends, most likely due to reactivated Paleozoic base-ment structures created during the original terrane amalgamation of the Central Asian Orogenic Belt continental crust. This strong basement heterogeneity may predispose it to reactivation, and make it sensitive to changes in the overall stress field of the Eurasian plate driven by forces at its margins and base. Detailed study of Mongolia’s multi-stage tectonic history may thus provide a key proxy for the long-term dynamics of the Eurasian plate. In

  18. Some new observations on the intra-plate deformation in the Central Indian Basin (CIB)

    Digital Repository Service at National Institute of Oceanography (India)

    Murthy, K.S.R.; Neprochnov, O.V.; Levchenko, O.V.; Rao, T.C.S.; Milanovsky, V.E.; Lakshminarayana, S.

    and from a detailed grid over a 45 x 45 km block, covering the area between 2 degrees N and 2 degrees S, and 81 degrees and 84 degrees E, indicate (1) a NE-SW trend for the faulted deformed blocks; (2) presence of fracture zones older than and unrelated...

  19. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    Science.gov (United States)

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  20. Radiation and Viscous Dissipation Effects on Laminar Boundary Layer Flow Nanofluid over a Vertical Plate with a Convective Surface Boundary Condition with Suction

    Directory of Open Access Journals (Sweden)

    K. Gangadhar

    2016-01-01

    Full Text Available The problem of laminar radiation and viscous dissipation effects on laminar boundary layer flow over a vertical plate with a convective surface boundary condition is studied using different types of nanoparticles. The general governing partial differential equations are transformed into a set of two nonlinear ordinary differential equations using unique similarity transformation. Numerical solutions of the similarity equations are obtained using the Nachtsheim-Swigert Shooting iteration technique along with the fourth order Runga Kutta method. Two different types of nanoparticles copper water nanofluid and alumina water nanofluid are studied. The effects of radiation and viscous dissipation on the heat transfer characteristics are discussed in detail. It is observed that as Radiation parameter increases, temperature decreases for copper water and alumina water nanofluid and the heat transfer coefficient of nanofluids increases with the increase of convective heat transfer parameter for copper water and alumina water nanofluids.

  1. Fingerprint matching by thin-plate spline modelling of elastic deformations

    NARCIS (Netherlands)

    Bazen, Asker M.; Gerez, Sabih H.

    2003-01-01

    This paper presents a novel minutiae matching method that describes elastic distortions in fingerprints by means of a thin-plate spline model, which is estimated using a local and a global matching stage. After registration of the fingerprints according to the estimated model, the number of matching

  2. MHD forced convective laminar boundary layer flow from a convectively heated moving vertical plate with radiation and transpiration effect.

    Science.gov (United States)

    Uddin, Md Jashim; Khan, Waqar A; Ismail, A I Md

    2013-01-01

    A two-dimensional steady forced convective flow of a Newtonian fluid past a convectively heated permeable vertically moving plate in the presence of a variable magnetic field and radiation effect has been investigated numerically. The plate moves either in assisting or opposing direction to the free stream. The plate and free stream velocities are considered to be proportional to x(m) whilst the magnetic field and mass transfer velocity are taken to be proportional to x((m-1)/2) where x is the distance along the plate from the leading edge of the plate. Instead of using existing similarity transformations, we use a linear group of transformations to transform the governing equations into similarity equations with relevant boundary conditions. Numerical solutions of the similarity equations are presented to show the effects of the controlling parameters on the dimensionless velocity, temperature and concentration profiles as well as on the friction factor, rate of heat and mass transfer. It is found that the rate of heat transfer elevates with the mass transfer velocity, convective heat transfer, Prandtl number, velocity ratio and the magnetic field parameters. It is also found that the rate of mass transfer enhances with the mass transfer velocity, velocity ratio, power law index and the Schmidt number, whilst it suppresses with the magnetic field parameter. Our results are compared with the results existing in the open literature. The comparisons are satisfactory.

  3. Earthquake prediction on boundaries of the Arabian Plate: premonitory chains of small earthquakes

    Science.gov (United States)

    Yaniv, M.; Agnon, A.; Shebalin, P.

    2009-12-01

    Target, i.e. all events are aftershocks; potential foreshocks are not a part of the chain. The algorithm is catalog sensitive. The Nueiba and Paphos events were recognized by the original RTP system (Shebalin et al., 2004), and were used for the calibration of the system before the prediction-in-advance phase was initiated. The detection of the smaller 1993 Red sea event (M6.1) is unique to the modified algorithm. These events, strongest in the catalog, were preceded by “foreshocks” within their chains as shown in the table. We see indications that different types of plate boundaries have different patterns of microseismicity: transform faults may have a clearer premonitory signal than normal faults. The three chains

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

    Science.gov (United States)

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

    2017-07-01

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

  5. Interpreting syndepositional sediment remobilization and deformation beneath submarine gravity flows; a kinematic boundary layer approach.

    NARCIS (Netherlands)

    Butler, Rob W.H.; Eggenhuisen, J.T.; Haughton, Peter; McCaffrey, William D.

    2015-01-01

    Turbidite sandstones and related deposits commonly contain deformation structures and remobilized sediment that might have resulted from post-depositional modification such as downslope creep (e.g. slumping) or density-driven loading by overlying deposits. However, we consider that deformation can o

  6. The EarthScope Plate Boundary Observatory Alaska Region: Highlights from the 2012 Summer Field Season

    Science.gov (United States)

    Enders, M.; Bierma, R. M.; Boyce, E. S.; Willoughby, H.; Fend, M.; Feaux, K.

    2012-12-01

    UNAVCO has now completed its fourth year of operation and maintenance of the 138 continuous GPS stations, 12 tiltmeters and 31 data communications relays that comprise the Alaska region of the EarthScope Plate Boundary Observatory (PBO). The successful operation of the autonomous GPS and tiltmeter network in Alaska continues to be a challenge, because of logistics, weather, and other difficulties related to working in Alaska. PBO engineers continue to work on network enhancements to make the stations more robust, while improving overall data quality and station uptime to better serve the EarthScope science community. In the summer of 2012, PBO engineers completed maintenance activities in Alaska, which resulted in a 95% operational status for the Alaska network within PBO. PBO engineers completed a total of 87 maintenance visits in the summer of FY2012, including 62 routine maintenance and 25 unscheduled maintenance visits to GPS and data communications stations. We present a number of highlights and accomplishments from the PBO 2012 summer field season in Alaska, for example the deployment of a newly designed methanol fuel cell at AV35, a critical station that serves as the main repeater for the real time network on Unimak Island. In addition, PBO engineers also completed the installation of three Inmarsat BGAN terminals for data telemetry following successful testing at AC60 Shemya. Lastly, PBO engineers completed scheduled battery replacements at most of the PBO stations on Unimak Island, in collaboration with the USGS/Alaska Volcano Observatory. In addition to routine maintenance and planned station improvements to sites in Alaska, numerous critical repairs were made at stations on Unimak Island and elsewhere to ensure that the PBO network continues to function well and continues to meet the requirements stipulated by the NSF. We also present some of the station failures unique to Alaska, which we encountered during the course of the 2012 field season, as well

  7. The Earthscope Plate Boundary Observatory Alaska Region an Overview of Network Operation, Maintenance and Improvement

    Science.gov (United States)

    Enders, M.; Boyce, E. S.; Bierma, R.; Walker, K.; Feaux, K.

    2011-12-01

    UNAVCO has now completed its third year of operation of the 138 continuous GPS stations, 12 tiltmeters and 31 communications relays that comprise the Alaska Region of the Earthscope Plate Boundary Observatory. Working in Alaska has been challenging due to the extreme environmental conditions encountered and logistics difficulties. Despite these challenges we have been able to complete each summer field season with network operation at 95% or better. Throughout the last three years we have analyzed both our successes and failures to improve the quality of our network and better serve the scientific community. Additionally, we continue to evaluate and deploy new technologies to improve station reliability and add to the data set available from our stations. 2011 was a busy year for the Alaska engineering team and some highlights from last year's maintenance season include the following. This spring we completed testing and deployment of the first Inmarsat BGAN satellite terminal for data telemetry at AC60 Shemya Island. Shemya Island is at the far western end of the Aleutian Islands and is one of the most remote and difficult to access stations in the PBO AK network. Until the installation of the BGAN, this station was offline with no data telemetry for almost one year. Since the installation of the BGAN in early April 2011 dataflow has been uninterrupted. This year we also completed the first deployments of Stardot NetCamSC webcams in the PBO Network. Currently, these are installed and operational at six GPS stations in Alaska, with plans to install several more next season in Alaska. Images from these cameras can be found at the station homepages linked to from the UNAVCO website. In addition to the hard work put in by PBO engineers this year, it is important that we recognize the contributions of our partners. In particular the Alaska Volcano Observatory, the Alaska Earthquake Information Center and others who have provided us with valuable engineering assistance

  8. The Plate Boundary Observatory (PBO) Network in the PNW region of the United States

    Science.gov (United States)

    Hafner, K.; Austin, K.; Feaux, K.; Jackson, M.; Fengler, K.; Doelger, S.

    2007-05-01

    The Pacific Northwest Region (PNW) of the United States contains a variety of geologic regions and tectonic problems. These include the Cascadia Subduction Zone, Mt. St. Helens and the transition to the Basin and Range province. Since September of 2003, the Plate Boundary Observatory (PBO), which is part of the larger NSF-funded EarthScope project, has been installing a network of continuously operating GPS, strainmeter and tiltmeter instruments. There are currently 78 GPS, 13 strainmeter/borehole seismometers, and 4 tiltmeters operating in the PNW region. The data from this network has already been used to study Episodic Tremor Events (ETS) during September 2005 and January 2007, and renewed activity on Mt. St. Helens that began on September 23, 2004. The goal is have 134 continuously operating GPS stations by the end of September 2008. The locations of the GPS stations were determined by scientific committees. Whenever possible, multiple instruments are deployed at the same location, and share power and communications resources. Examples of this are GPS antennas mounted on top of strainmeter boreholes in the forearc region of western Washington and tiltmeters collecting data through GPS receivers on Mt. St. Helens. In addition, a number of stations provide real time kinematic data to professional surveyors within the region. During the fall of 2006, a 16 GPS and 4 tiltmeter station network was completed on Mt. St. Helens. Results from analysis of both PBO and USGS GPS stations on the mountain, show a radially inward and downward motion, with the maximum vertical offsets high on the mountain and the maximum horizontal offsets located at distances of 5-10km from the crater. Displacements are small over the 2004-present eruption with a maximum of 3cm of inward movement. GPS stations installed high on the mountain experience severe weather and heavy rime accumulations for approximately 6 months of the year. Ice build-up causes distortion of the GPS antenna phase

  9. The Plate Boundary Observatory: Current status and plans for the next five years

    Science.gov (United States)

    Mattioli, G. S.; Feaux, K.; Meertens, C. M.; Mencin, D.; Miller, M.

    2013-12-01

    UNAVCO currently operates and maintains the NSF-funded Plate Boundary Observatory (PBO), which is the geodetic facility of EarthScope. PBO was designed and built from 2003 to 2008 with $100M investment from the NSF Major Research Equipment and Facilities Construction (MREFC) Program. UNAVCO operated and maintained PBO under a Cooperative Agreement (CA) with NSF from 2008 to 2013 and will continue PBO O&M for the next five years as part of the new Geodesy Advancing Geosciences and EarthScope (GAGE) Facility. PBO is largest continuous GPS and borehole geophysical network in the Americas, with 1100 continuous Global Positioning System (cGPS) sites, including several with multiple monuments, 79 boreholes, with 75 tensor strainmeters, 78 short-period, 3-component seismometers, and pore pressure sensors at 23 sites. PBO also includes 26 tiltmeters deployed at volcanoes in Alaska, Mt St Helens, and Yellowstone caldera and 6 long-baseline laser strainmeters. Surface meteorological sensors are collocated at 154 GPS sites. UNAVCO provides high-rate (1 Hz), low-latency (streams (RT-GPS) from 382 stations in PBO. UNAVCO has delivered over 62 Tb of geodetic data to the EarthScope community since its PBO's inception in 2004. Over the past year, data return for the cGPS component of PBO is 98%, well above the data return metric of 85% set by the NSF, a result of efforts to upgrade power systems and communications infrastructure. In addition, PBO has set the standard for the design, construction, and operation of other multi-hazard networks across the Americas, including COCONet in the Caribbean region and TLALOCNet in Mexico. Funding to support ongoing PBO O&M has declined from FY2012 CA levels under the new GAGE Facility. The implications for data return and data quality metrics as well as replacement of aging PBO GPS instruments with GNSS-compatible systems are as yet unknown. A process to assess the cost of specific PBO components, data rates, enhanced capabilities, and method

  10. The Teisseyre-Tornquist Zone - early Palaeozoic strike-slip plate boundary or Ediacaran rifted margin of Baltica?

    Science.gov (United States)

    Mazur, Stanislaw; Krzywiec, Piotr; Malinowski, Michal; Lewandowski, Marek; Buffenmeyer, Vinton; Green, Christopher

    2016-04-01

    area is dominated by high density lower crustal bodies similar to those that are found along present-day passive continental margins. Moreover, an extensive succession of the uppermost Neoproterozoic sediments is emplaced outboard of the southeastern section of the TTZ. These results obtained do not support the occurrence of a Palaeozoic terrane boundary along the TTZ. Instead, it is suggested that the crystalline basement of the EEC extends westward beyond the TTZ and continues in the substratum of the Permo-Mesozoic basin of central and western Poland. If the crustal keel underneath the TTZ indeed represents a fossil plate boundary, it must have formed in the Precambrian during the amalgamation of the Rodinia supercontinent. However, the contrast of crustal thickness across the TTZ between the EEC and the adjacent Palaeozoic Platform may have formed later during the Ediacaran rifting and subsequent break-up of the Tornquist Ocean. The Caledonian collisional suture must be located farther southwest in western Poland or NE Germany and deeply concealed beneath a thick cover of Palaeozoic and younger sediments.

  11. Characterizing twist grain boundaries in BCC Nb by molecular simulation: Structure and shear deformation

    Science.gov (United States)

    Liu, Zeng-Hui; Feng, Ya-Xin; Shang, Jia-Xiang

    2016-05-01

    Atomic scale modeling was used to study the structure, energy and shear behaviors of (110) twist grain boundaries (TWGBs) in body-centered cubic Nb. The relation between grain boundary energy (GBE) and the twist angle θ agrees well with the Read-Shockley equation in low-angle range. At higher angles, the GBEs show no distinct trend with the variation of the twist angle or the density of coincident lattice sites. All (110) twist boundaries can be classified into two types: low-angle grain boundaries (LAGBs) and high-angle grain boundaries (HAGBs). LAGBs contain a hexagonal dislocation network (HDN) which is composed of 1/2 [ 111 ], 1/2 [ 1 bar 1 bar 1 ] and [001] screw dislocations. HAGBs can be classified into three sub-types further: special boundaries with low Σ, boundaries in the vicinity of special boundaries with similar structures and ordinary HAGBs consisting of periodic patterns. Besides, a dependence of grain boundary shear response vs the twist angle over the entire twist angle range is obtained. Pure sliding behavior is found at all TWGBs. When θ < 12°, the flow stress of LAGBs is found to be correlated with the HDNs and decreases with the increasing twist angle. For ordinary HAGBs, the magnitude of flow stress is around 0.8-1.0 GPa and the twist angle has little effect on the anisotropy mobility. For special grain boundaries with low Σ, the boundary structures govern the GBEs and shear motion behavior significantly.

  12. Punctuated Neogene tectonics and stratigraphy of the African-Iberian plate-boundary zone: concurrent development of Betic-Rif basins (southern Spain, northern Morocco)

    NARCIS (Netherlands)

    Sissingh, W.

    2008-01-01

    This paper integrates the sequence stratigraphic and tectonic data related to the Neogene geodynamic and palaeogeographic development of the African-Iberian plate boundary zone between Spain and Morocco. Though the dating of individual tectonostratigraphic sequences and their delimiting sequence

  13. Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

    KAUST Repository

    Cheng, W.

    2015-11-11

    © 2015 Cambridge University Press. We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which can calculate the time- and space-dependent skin-friction vector field at the wall, at the resolved scale. By combining the virtual-wall model with the stretched-vortex subgrid-scale (SGS) model, we construct a self-consistent framework for the LES of separating and reattaching turbulent wall-bounded flows at large Reynolds numbers. The present LES methodology is applied to two different experimental flows designed to produce separation/reattachment of a flat-plate turbulent boundary layer at medium Reynolds number Reθ based on the momentum boundary-layer thickness θ. Comparison with data from the first case at demonstrates the present capability for accurate calculation of the variation, with the streamwise co-ordinate up to separation, of the skin friction coefficient, Reθ, the boundary-layer shape factor and a non-dimensional pressure-gradient parameter. Additionally the main large-scale features of the separation bubble, including the mean streamwise velocity profiles, show good agreement with experiment. At the larger Reθ = 11000 of the second case, the LES provides good postdiction of the measured skin-friction variation along the whole streamwise extent of the experiment, consisting of a very strong adverse pressure gradient leading to separation within the separation bubble itself, and in the recovering or reattachment region of strongly-favourable pressure gradient. Overall, the present two-dimensional wall model used in LES appears to be capable of capturing the quantitative features of a separation-reattachment turbulent boundary-layer flow at low to moderately large Reynolds numbers.

  14. Influence of inclined twin boundaries on the deformation behavior of Cu micropillars

    Energy Technology Data Exchange (ETDEWEB)

    Imrich, P.J., E-mail: peter.imrich@stud.unileoben.ac.at [Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstraße 12, 8700 Leoben (Austria); Kirchlechner, C., E-mail: c.kirchlechner@mpie.de [Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf (Germany); Department of Materials Physics, Montanuniversität, Jahnstraße 12, 8700 Leoben (Austria); Dehm, G., E-mail: dehm@mpie.de [Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf (Germany)

    2015-08-26

    In situ micromechanical compression tests on Cu pillars were performed to evaluate the influence of twin boundaries on the mechanical behavior. The 1 µm sized Cu samples on a Si substrate prepared by focused ion beam milling were either single crystalline or contained 2–5 twin boundaries that were inclined to the compression direction. The strengths of the pillars vary, depending on the crystal orientation, associated twin boundary inclination and orientation of slip systems. Results show, that multiple slip systems are activated in each pillar. However, slip parallel to the twin boundaries prevails due to the long mean free path for dislocation movement.

  15. Magnetic fabric (AMS, AAR) of the Santa Marta batholith (northern Colombia) and the shear deformation along the Caribbean Plate margin

    Science.gov (United States)

    Salazar, Carlos A.; Bustamante, Camilo; Archanjo, Carlos J.

    2016-10-01

    Anisotropy of low-field magnetic susceptibility (AMS) and anhysteretic remanence (AAR) were measured in the Santa Marta Batholith formed by subduction of the Caribbean Plate beneath the northern South America. The batholith, elongated in the N-S direction, records multiple pulses of quartzdiorite to tonalite and granodiorite magmas between 58 and 49 Ma. The high mean magnetic susceptibility (4 × 10-3 SI) combined with thermomagnetic and partial magnetic remanence measurements indicate that the magnetic susceptibility depends on Ti-poor magnetite. AMS is defined by ellipsoids that are dominantly oblate. The foliation was used to distinguish a narrow band of E-trending magnetic structures that separate the batholith in two lobes. The southern lobe is characterized by foliations that are broadly parallel to the contact with the wall rocks, while the northern lobe by foliations oblique to the batholith elongation. Late tonalitic magmas dated at c. 50 Ma record, in turn, a fabric apparently controlled by E-trending tectonic events. Partial AAR indicates that the subfabrics of magnetite with different grain sizes are nearly parallel to AMS, therefore discarding the possibility of superposed fabrics with different orientations. The magnetic fabric pattern is consistent with a magma emplaced in an arc setting deformed by a dextral shear. Synthetic extensional shear bands localize the magmatic deformation along East-trending corridors that probably were exploited to emplace the late magmatic pulses. Accretion of the Eocene batholith and the Late Cretaceous metasedimentary host-rocks to the South American continent defines a major strike-slip shear suture that resulted from the oblique convergence of the Caribbean Plate.

  16. Compressive loading at the end plate directly regulates flow and deformation of the basivertebral vein: an analytical study

    Directory of Open Access Journals (Sweden)

    Chen Hsiang-Ho

    2006-12-01

    Full Text Available Abstract Background Metastatic diseases and infections frequently involve the spine. This is the result of seeding of the vertebral body by tumor cells or bacteria delivered by venous blood from Batson's plexus, which is hypothesized to enter the vertebral body via the epidural veins. Isolated spinal segments deform significantly at the bony end plate when under compression. This deformation could cause a volume change of the vertebral body and may be accompanied by retrograde flow of venous blood. To date, this process has not been investigated quantitatively. The purpose of this study was to determine the volume changes of the vertebral body and basivertebral vein for a vertebral body under compression. Methods A three-dimensional finite element mesh model of the L4 segment with both adjacent discs was modified from a 3-D computed tomography scan image. An octagon representing the basivertebral vein was introduced into the center of the vertebral body in the model. Four compressive orientations (1500 N were applied on the top disc. The volume change of the vertebral body model and the basivertebral vein were then computed. Results The volume change of the vertebral body was about 0.1 cm3 (16.3% of the basivertebral vein for the four loading conditions. The maximum cross-sectional area reductions of the basivertebral vein and volume reduction were 1.54% and 1.02%, for uniform compression. Conclusion Our study quantified the small but significant volume change of a modeled vertebral body and cross-sectional areas and that of the basivertebral vein, due to the inward bulging of the end plate under compression. This volume change could initiate the reverse flow of blood from the epidural venous system and cause seeding of tumors or bacterial cells.

  17. Dislocation-accommodated grain boundary sliding as the major deformation mechanism of olivine in the Earth's upper mantle.

    Science.gov (United States)

    Ohuchi, Tomohiro; Kawazoe, Takaaki; Higo, Yuji; Funakoshi, Ken-Ichi; Suzuki, Akio; Kikegawa, Takumi; Irifune, Tetsuo

    2015-10-01

    Understanding the deformation mechanisms of olivine is important for addressing the dynamic processes in Earth's upper mantle. It has been thought that dislocation creep is the dominant mechanism because of extrapolated laboratory data on the plasticity of olivine at pressures below 0.5 GPa. However, we found that dislocation-accommodated grain boundary sliding (DisGBS), rather than dislocation creep, dominates the deformation of olivine under middle and deep upper mantle conditions. We used a deformation-DIA apparatus combined with synchrotron in situ x-ray observations to study the plasticity of olivine aggregates at pressures up to 6.7 GPa (that is, ~200-km depth) and at temperatures between 1273 and 1473 K, which is equivalent to the conditions in the middle region of the upper mantle. The creep strength of olivine deforming by DisGBS is apparently less sensitive to pressure because of the competing pressure-hardening effect of the activation volume and pressure-softening effect of water fugacity. The estimated viscosity of olivine controlled by DisGBS is independent of depth and ranges from 10(19.6) to 10(20.7) Pa·s throughout the asthenospheric upper mantle with a representative water content (50 to 1000 parts per million H/Si), which is consistent with geophysical viscosity profiles. Because DisGBS is a grain size-sensitive creep mechanism, the evolution of the grain size of olivine is an important process controlling the dynamics of the upper mantle.

  18. Consideration of SH-wave fundamental modes in piezoelectromagnetic plate: electrically open and magnetically open boundary conditions

    Science.gov (United States)

    Zakharenko, A. A.

    2013-11-01

    This report studies the dispersive wave propagation in the transversely isotropic (6 mm) piezoelectromagnetic (PEM) plate when the mechanical, electrical, and magnetic boundary conditions for both the upper and lower free surfaces of the plate are as follows: the mechanically free, electrically open, and magnetically open surfaces. This study follows some original results obtained in book. The fundamental modes' dispersion relations are graphically shown for the following well-known PEM composite materials: BaTiO3-CoFe2O4 and PZT-5H-Terfenol-D. It is natural that for large values of the nondimensional parameter kd (k is the wave number and d is the plate half-thickness), the velocities of both the fundamental modes approach the surface shear-horizontal wave called the piezomagnetic exchange surface Melkumyan wave. It is well known that plate waves are usually utilized in the nondestructive testing and evaluation, for instance, in the airspace industry. Also, PEM materials are used as smart ones in various technical devices such as dispersive wave delay lines, (biochemi)sensors, lab-on-a-chip, etc.

  19. Boundary layer flow and heat transfer on a moving plate in a copper-water nanofluid using Buongiorno model

    Science.gov (United States)

    Bakar, Nor Ashikin Abu; Bachok, Norfifah; Arifin, Norihan Md.

    2016-06-01

    The study of the steady two dimensional boundary layer flow of a copper (Cu)-water nanofluid on a moving plate is investigated. The assumption is the plate moves in the same or opposite direction to the free stream. The nonlinear partial differential equations are transformed into nonlinear ordinary differential equations using a similarity variables,then a shooting technique is used to solved it numerically. The numerical results for skin friction coefficient, the local Nusselt number, the local Sherwood number as well as the velocity, temperature and concentration profiles are obtained. The effect of nanoparticle volume fraction, Brownian motion and thermophoresis parameters on heat transfer are examined. The results show that the local Nusselt number and the local Sherwood number increase with increasing in the Brownian motion parameter Nb and thermophoresis parameter Nt.

  20. Disruption of Esrom and Ryk identifies the roof plate boundary as an intermediate target for commissure formation.

    Science.gov (United States)

    Hendricks, Michael; Mathuru, Ajay Sriram; Wang, Hui; Silander, Olin; Kee, Michelle Zhi Ling; Jesuthasan, Suresh

    2008-02-01

    Growth cones are guided to their final destination by intermediate targets. Here, we identify intermediate targets and signaling components acting on zebrafish habenula commissural axons. Live imaging establishes that axons pause at the medial habenula before and after crossing the roof plate. esrom mutants axons fail to advance beyond the ipsilateral medial habenula. Tsc2 function is reduced in mutant axons, indicating cell autonomous defects in signaling. Consistent with signaling properties changing outside the roof plate, EphB is surface localized on axon segments within a zone demarcated by the medial habenula. wnt4a is expressed in the medial habenula and morpholino knockdown causes loss of the commissure. Electroporation of truncated Ryk causes axons to reenter the midline after reaching the contralateral habenula. These data identify Esrom as a mediator of growth cone navigation at an intermediate target and underscore the importance of midline boundaries as signaling centers for commissure formation.

  1. Effect of Chord Splice Joints on Force Distribution and Deformations in Trusses with Punched Metal Plate Fasteners

    DEFF Research Database (Denmark)

    Ellegaard, Peter

    2007-01-01

    The span of roof trusses with punched metal plate fasteners (nail plates) makes it often necessary to use splice joints in the top and bottom chords. In the finite element models used for design of the trusses these splice joints are normally assumed to be either rotationally stiff or pinned - th...... of splice joints on section forces and displacements are discussed considering the results from finite element calculations for a fink truss. It seems that the guidelines for treating splice joints as rotationally stiff do not necessarily lead to more realistic truss models....... - their real behaviour is semi-rigid. The influence of splice joints on the distribution of member forces and rotations in the splice joints is investigated in this paper. A finite element program, TrussLab, where the splice joints are given semi-rigid properties is used to analyse the effect of splice joints...... if their deformation has no significant effect upon the distribution of member forces according to Eurocode 5. Two simple guidelines for the design and location of splice joints are given in Eurocode 5 for treating the splice joints as rotationally stiff. The reasonability of these guidelines and the influence...

  2. On mixed and displacement finite element models of a refined shear deformation theory for laminated anisotropic plates

    Science.gov (United States)

    Reddy, J. N.

    1986-01-01

    An improved plate theory that accounts for the transverse shear deformation is presented, and mixed and displacement finite element models of the theory are developed. The theory is based on an assumed displacement field in which the inplane displacements are expanded in terms of the thickness coordinate up to the cubic term and the transverse deflection is assumed to be independent of the thickness coordinate. The governing equations of motion for the theory are derived from the Hamilton's principle. The theory eliminates the need for shear correction factors because the transverse shear stresses are represented parabolically. A mixed finite element model that uses independent approximations of the displacements and moments, and a displacement model that uses only displacements as degrees of freedom are developed. A comparison of the numerical results for bending with the exact solutions of the new theory and the three-dimensional elasticity theory shows that the present theory (and hence the finite element models) is more accurate than other plate-theories of the same order.

  3. Plate Boundary Observatory Infrastructure and Data Products in Education and Outreach

    Science.gov (United States)

    Eriksson, S. C.; Barbour, K.; Lee, E.

    2005-12-01

    As one of three major components of NSF's EarthScope program, the Plate Boundary Observatory (PBO) encourages the integration of research and education. Informing various communities about the current work of PBO and the scientific discoveries related to the use of this instrumentation has contributed to the success of PBO during the first two years of the EarthScope project. UNAVCO(PBO), IRIS (USArray), and the EarthScope project office work together to integrate Education and Outreach (E&O) opportunities into a program that is greater than the sum of its parts and yet maintains the identity of each organization. Building and maintaining the PBO website, documenting and archiving activities of PBO, providing short courses for professional development of scientists using EarthScope data, and developing higher level data products with an appropriate educational framework are a few of the activities that provide both challenges and opportunities. The internet, particularly the World Wide Web, has become the primary tool for disseminating information to various audiences. The primary goals of the PBO website are to provide current information on the progress of GPS and Strainmeter facility construction; to provide access to different levels of data products; and to facilitate networking with and among scientists. Challenges for the PBO website include publishing current stories on installation projects while coordinating with field engineers on a regular basis; providing near to real time updates and maintaining quality assurance processes; and defining personnel requirements for a maintaining a dynamic website. Currently, archived photographs, web diaries, and numerous web highlights document PBO's success and provide a visual record of PBO's accomplishments and behind-the-scene activities over the last two years. The community charged PBO with increasing the number of scientists using its data. UNAVCO does this by providing short courses for professional development

  4. EarthScope: Cyberinfrastructure to access Plate Boundary Observatory data products and services

    Science.gov (United States)

    Meertens, C. M.; Mattioli, G. S.; Miller, M.; Boler, F. M.; Crosby, C. J.; Mencin, D.; Phillips, D. A.; Snett, L.

    2013-12-01

    The wealth of data from geodetic observing systems, especially the Plate Boundary Observatory (PBO), presents major data management challenges. The challenges are driven by ingenious new uses of Global Positioning System (GPS) data, demands for higher-rate, lower latency data, the need for continued access and long term preservation of archival data, the expansion of data users into other science, engineering and commercial arenas, and the growth of enhanced products that expand the utility of the data. To meet these challenges, UNAVCO has established a comprehensive suite of data services encompassing sensor network data operations, data product generation (through the activities of partners at Massachusetts Institute of Technology, Central Washington University, New Mexico Institute of Mining and Technology, and the University of California, San Diego - UCSD), data management, access and archiving, and advanced cyberinfrastructure. PBO sensor systems include 1,100 continuously operating GPS stations, 79 borehole geophysical sites (with a combination of strainmeters, tiltmeters, seismometers, pore pressure gauges, and meteorological sensors), and 6 long baseline strainmeters. Imaging data acquired for EarthScope include large volumes of satellite synthetic aperture radar (SAR) and airborne LiDAR data. Core data products such as daily GPS position time series and derived crustal motion velocities have been augmented with real-time data streams and positions calculated every second from 367 PBO stations. Higher rate (5 Hz) data files are available for applications such as GPS seismology. Efforts are underway with UCSD to integrate GPS and accelerometers at a subset of PBO sites to increase the reliability and capability of the observations. These observations have utility for research and hazards mitigation. Ingenious methods of GPS data analysis, developed by the University of Colorado and the University Corporation for Atmospheric Research, measure snow depth

  5. Secular and annual hydrologic effects from the Plate Boundary Observatory GPS network

    Science.gov (United States)

    Meertens, C. M.; Wahr, J. M.; Borsa, A. A.; Jackson, M. E.; Herring, T.

    2009-12-01

    The Plate Boundary Observatory (PBO) GPS network is providing accurate and spatially coherent vertical signals that can be interpreted in terms of hydrological loading and poroelastic effects from both natural and anthropogenic changes in water storage. Data used for this analysis are the precise coordinate time series produced on a daily basis by PBO Analysis Centers at New Mexico Institute of Mining and Technology and at Central Washington University and combined by the Analysis Center Coordinator at the Massachusetts Institute of Technology. These products, as well as derived velocity solutions, are made freely available from the UNAVCO Data Center in Boulder. Analysis of secular trends and annual variations in the time series was made using the analysis software of Langbein, 2008. Spatial variations in the amplitude and phase of the annual vertical component of motion allow for identification of anthropogenic effects due to water pumping, irrigation, and reservoir lake variations, and of outliers due to instrumental or other local site effects. Vertical annual signals of 8-10 mm peak-to-peak amplitude are evident at stations in the mountains of northern and central California and the Pacific Northwest. The peak annual uplift is in October and is correlated to hydrological loading effects. Mountainous areas appear to be responding elastically to the load of the water contained in surface soil, fractures, and snow. Vertical signals are highest when the water load is at a minimum. The vertical elastic hydrologic loading signal was modeled using the 0.25 degree community NOAH land-surface model (LSM) and generally fits the observed GPS signal. Addition comparisons will be made using the Mosaic LSM and the NOAA “Leaky Bucket” hydrologic model. In contrast to mountain stations that are installed principally in bedrock, stations in the valleys of California are installed in sediments. Observations from these stations show greater spatial variability ranging from

  6. EarthScope's Plate Boundary Observatory as the Mother of Invention (Invited)

    Science.gov (United States)

    Blewitt, G.; Hammond, W. C.; Kreemer, C.

    2013-12-01

    The Plate Boundary Observatory (PBO) component of EarthScope includes a network of over 1,100 permanent, continuously operating GPS stations. After 5 years of site selection, permitting, and construction, the network was completed in 2008. Having such an unprecedented number of high quality stations in western North America has enabled us to image geology in action, as it happens, such as contemporary uplift of the Sierra Nevada, and block rotation in the Walker Lane. Yet, when PBO was in its planning stages, questions were raised as to whether GPS analysis could keep up with the flood of data, while producing results with the highest achievable accuracy. The general consensus was that the challenge would be met by a combination of innovative data processing methods together with the inevitable progress in computer speed and capacity. Various innovations made by the geodetic community over the last decade have enabled massive operational processing of GPS data with high accuracy. For example, now in 2013, the Nevada Geodetic Laboratory operationally produces position time series and quality assurance data from all ~7,000 GPS geodetic stations in the world that make data publicly available. Of these stations, 4,000 have daily time series updated the next day, and 2,000 have 5-minute time series updated within 1-2 hours of real time. The RMS precision of daily positions for well-sited stations are at the level of 1-2 mm horizontal, and 3-6 mm vertical in the International Terrestrial Reference Frame (ITRF). For 5-minute positions, the precision is at the level of 6-12 mm horizontal, and 15-30 mm vertical. Here we review some of the innovations that have made all of this possible, which were in part driven by challenges presented by EarthScope. First of all, at the data processing level, much creative effort went into making computer processing time scale linearly with the number of GPS stations. The Precise Point Positioning (PPP) technique invented in 1997 has been

  7. The EarthScope Plate Boundary Observatory Distributed Data Management System

    Science.gov (United States)

    Anderson, G.; Eakins, J.; Hodgkinson, K.; Matykiewicz, J.; Beldyk, M.; Blackman, B.; Boler, F.; Henderson, B.; Hoyt, B.; Lee, E.; Persson, E.; Smith, J.; Torrez, D.; Wright, J.; Jackson, M.; Meertens, C.

    2007-05-01

    EarthScope is an ambitious multi-year project funded by the United States National Science Foundation to explore the structure and dynamics of the North American continent using a wide range of geophysical methods. The Plate Boundary Observatory (PBO), being built by UNAVCO, is the geodetic component of EarthScope, and will comprise 880 continuous GPS stations, 103 borehole strainmeter stations, 28 tiltmeters, and five laser strainmeters; in addition, PBO will manage data for 209 existing GPS stations and 11 GPS stations installed by the USArray segment of EarthScope. As of February 2007, 561 of these stations have been installed. PBO data flow is managed from the PBO Boulder Network Operations Center (NOC), located at UNAVCO Headquarters. Automated systems at the NOC retrieve data from our stations at least daily, monitor the status of the network and alert operators to problems, and pass data on for analysis, archiving, and distribution. Real-time network status can be found at http:pboweb.unavco.org/soh_map. PBO's analysis centers generate high-quality derived data products from PBO raw data. Two centers, at Central Washington University and the New Mexico Institute of Mining and Technology, process raw GPS data to produce initial PBO GPS products including network solutions and station position time series, andthese products are combined by the Analysis Center Coordinator at MIT to produce the official PBO GPS products. Two analysis centers, at UNAVCO's Socorro office and the University of California, San Diego, process data from the PBO borehole and laser strainmeter networks and produce cleaned time series of shear, areal, and linear strain, Earth tides, pore fluid pressure, and other parameters. The UNAVCO Facility archives and distributes all PBO GPS data products and runs a secondary archive offsite; to date, these centers hold more than 2.5 TB of PBO products. The IRIS Data Management Center and Northern California Earthquake Data Center archive and

  8. Tethyan collision forces and the stress field of the Eurasian plate

    NARCIS (Netherlands)

    Warners-Ruckstuhl, K.N.; Govers, R.; Wortel, R.

    2013-01-01

    Resistive forces along convergent plate boundaries have a major impact on surface deformation, most visibly at collisional plate boundaries. Although quantification of these forces is key to understanding the evolution and present state of mountain belts, they remain highly uncertain due to the comp

  9. Crustal structure and seismicity distribution adjacent to the Pacific and North American plate boundary in southern California

    OpenAIRE

    Hauksson, Egill

    2000-01-01

    New three-dimensional (3-D) V_P and V_P/V_S models are determined for southern California using P and S-P travel times from local earthquakes and controlled sources. These models confirm existing tectonic interpretations and provide new insights into the configuration of geological structures at the Pacific-North America plate boundary. The models extend from the U.S.-Mexico border in the south to the southernmost Coast Ranges and Sierra Nevada in the north and have a 15-km horizontal grid sp...

  10. Global stability of plasmas with helical boundary deformation and net toroidal current against n=1,2 external modes

    Energy Technology Data Exchange (ETDEWEB)

    Ardela, A.; Cooper, W.A. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1996-09-01

    In this paper we resume a numerical study of the global stability of plasma with helical boundary deformation and non null net toroidal current. The aim was to see whether external modes with n=1,2 (n toroidal mode number) can be stabilized at values of {beta} inaccessible to the tokamak. L=2,3 configurations with several aspect ratios and different numbers of equilibrium field periods are considered. A large variety of toroidal current densities and different pressure profiles are taken into account. Mercier stability is also investigated. (author) 4 figs., 6 refs.

  11. The reliability of the improved eN method for the transition prediction of boundary layers on a flat plate

    Institute of Scientific and Technical Information of China (English)

    SU CaiHong

    2012-01-01

    The transition criterion in the improved eN method is that transition would occur whenever the velocity amplitude of disturbance reaches 1%-2% of the free stream velocity,while in the conventional eN method,the N factor is an empirical factor.In this paper the reliability of this key assumption in the improved eN method is checked by results of transition prediction by using the Parabolized Stability Equations (PSE).Transition locations of an incompressible boundary layer and a hypersonic boundary layer at Mach number 6 on a flat plate are predicted by both the improved eN method and the PSE method.Results from both methods agree fairly well with each other,implying that the transition criterion proposed in the improved eN method is reliable.

  12. PLATE

    DEFF Research Database (Denmark)

    Kling, Joyce; Hjulmand, Lise-Lotte

    2008-01-01

    ’s level of English is sufficient for the increasing number of courses offered in English each semester. This paper addresses these concerns and describes a pilot project initiated in 2003 at CBS to gauge the overall English language proficiency of those teaching content courses in English. Through......Copenhagen Business School (CBS) finds itself needing to address the issue of English-medium instruction for its increasing number of foreign exchange and full degree students. With internationalisation as a main pillar of the institution’s agenda, there are concerns whether the teaching faculty...... the Project in Language Assessment for Teaching in English (PLATE) language professionals from CBS’s Language Center observe teachers and provide feedback using evaluation criteria from the Common European Framework for Reference (CEFR) supplemented by some additional criteria which take the LSP nature...

  13. PLATE

    DEFF Research Database (Denmark)

    Kling, Joyce; Hjulmand, Lise-Lotte

    2008-01-01

    Copenhagen Business School (CBS) finds itself needing to address the issue of English-medium instruction for its increasing number of foreign exchange and full degree students. With internationalisation as a main pillar of the institution’s agenda, there are concerns whether the teaching faculty......’s level of English is sufficient for the increasing number of courses offered in English each semester. This paper addresses these concerns and describes a pilot project initiated in 2003 at CBS to gauge the overall English language proficiency of those teaching content courses in English. Through...... the Project in Language Assessment for Teaching in English (PLATE) language professionals from CBS’s Language Center observe teachers and provide feedback using evaluation criteria from the Common European Framework for Reference (CEFR) supplemented by some additional criteria which take the LSP nature...

  14. Tectonic isolation of the Levant basin offshore Galilee-Lebanon effects of the Dead Sea fault plate boundary on the Levant continental margin, eastern Mediterranean

    Science.gov (United States)

    Schattner, U.; Ben-Avraham, Z.; Lazar, M.; Hüebscher, C.

    2006-11-01

    The continental margin of the central Levant, offshore northern Israel and southern Lebanon is characterized by a sharp continental-oceanic crustal transition, exhibited on the bathymetry as a steep continental slope. At the base of the slope a narrow zone of faulting deforms the upper Messinian-recent sedimentary sequence. Further into the basin no major deformations are observed. However, onland a restraining bend along the Dead Sea fault plate boundary results in the formation of the Lebanon and anti-Lebanon mountain ranges, which exhibit a large positive isostatic anomaly not compensated at depth. All these geologic features follow a NNE-SSW trend. A dense network of multi-channel and single-channel seismic profiles, covering 5000 km of ship-track offshore northern Israel and southern Lebanon, was analyzed for the purpose of characterizing the continental margin. Additional seismic surveys covering the area between the Levant margin and the Cyprean arc were examined. Data were then incorporated with magnetic, gravity and earthquake measurements to reveal the deep crustal structure of the area and integrated with bathymetry data to describe the behavior of the young sedimentary basin fill. Results indicate that the Levant basin, offshore northern Israel and southern Lebanon (up to Beirut) is more-or-less unaffected by the intense tectonic deformation occurring onland. The transition between the deformed area onland and the undeformed Levant basin occurs along the base of the continental slope. Along the base, the upper Messinian-recent sedimentary sequence is cut by two sets of faults: shallow growth faults resulting from salt tectonics and high angle faults, marking the surface expression of a deeper crustal discontinuity - the marine extension of the Carmel fault zone. The central Levant continental margin is being reactivated by transpressional faulting of the marine continuation of the Carmel fault, at the base of the continental slope. This fault system

  15. DSMC simulations of leading edge flat-plate boundary layer flows at high Mach number

    Science.gov (United States)

    Pradhan, Sahadev, , Dr.

    2017-01-01

    The flow over a 2D leading-edge flat plate is studied at Mach number Ma = (Uinf /√{kBTinf / m }) in the range Boltzmann constant. The variation of streamwise velocity, temperature, number-density, and mean free path along the wall normal direction away from the plate surface is studied. The qualitative nature of the streamwise velocity at high Mach number is similar to those in the incompressible limit (parabolic profile). However, there are important differences. The amplitudes of the streamwise velocity increase as the Mach number increases and turned into a more flatter profile near the wall. There is significant velocity and temperature slip at the surface of the plate, and the slip increases as the Mach number is increased. It is interesting to note that for the highest Mach numbers considered here, the streamwise velocity at the wall exceeds the sound speed, and the flow is supersonic throughout the flow domain.

  16. Influence of conducting plate boundary conditions on the transverse envelope equations describing intense ion beam transport

    Directory of Open Access Journals (Sweden)

    Steven M. Lund

    2004-06-01

    Full Text Available In typical diagnostic applications, intense ion beams are intercepted by a conducting plate associated with devices used to measure beam phase-space projections. This results in the transverse space-charge field near the plate being shorted out, rendering simple envelope models with constant space-charge strength inaccurate. Here we develop corrected envelope models based on analytical calculations to account for this effect on the space-charge term of the envelope equations, thereby removing a systematic source of error in the equations and enabling more accurate comparisons with experiment. For common intense beam parameters, we find that the envelope correction occurs primarily in the envelope angles near the plate and that the effect can be large enough to degrade precision beam matching in periodic transport lattices. Results are verified with 3D self-consistent particle-in-cell simulations based on intense beam experiments associated with driver development for heavy-ion fusion.

  17. Stress Transfer Processes during Great Plate Boundary Thrusting Events: A Study from the Andaman and Nicobar Segments

    Science.gov (United States)

    Andrade, V.; Rajendran, K.

    2010-12-01

    The response of subduction zones to large earthquakes varies along their strike, both during the interseismic and post-seismic periods. The December 26, 2004 earthquake nucleated at 3° N latitude and its rupture propagated northward, along the Andaman-Sumatra subduction zone, terminating at 15°N. Rupture speed was estimated at about 2.0 km per second in the northern part under the Andaman region and 2.5 - 2.7 km per second under southern Nicobar and North Sumatra. We have examined the pre and post-2004 seismicity to understand the stress transfer processes within the subducting plate, in the Andaman (10° - 15° N ) and Nicobar (5° - 10° N) segments. The seismicity pattern in these segments shows distinctive characteristics associated with the outer rise, accretionary prism and the spreading ridge, all of which are relatively better developed in the Andaman segment. The Ninety East ridge and the Sumatra Fault System are significant tectonic features in the Nicobar segment. The pre-2004 seismicity in both these segments conform to the steady-state conditions wherein large earthquakes are fewer and compressive stresses dominate along the plate interface. Among the pre-2004 great earthquakes are the 1881 Nicobar and 1941 Andaman events. The former is considered to be a shallow thrust event that generated a small tsunami. Studies in other subduction zones suggest that large outer-rise tensional events follow great plate boundary breaking earthquakes due to the the up-dip transfer of stresses within the subducting plate. The seismicity of the Andaman segment (1977-2004) concurs with the steady-state stress conditions where earthquakes occur dominantly by thrust faulting. The post-2004 seismicity shows up-dip migration along the plate interface, with dominance of shallow normal faulting, including a few outer rise events and some deeper (> 100 km) strike-slip faulting events within the subducting plate. The September 13, 2002, Mw 6.5 thrust faulting earthquake at

  18. The Campaign GPS Component of the Plate Boundary Observatory (PBO): New Tools, New Strategies and New Opportunities to Support EarthScope Investigations

    Science.gov (United States)

    Phillips, D. A.; Greenberg, J.; Sklar, J.; Meertens, C. M.; Andreatta, V.; Feaux, K.

    2004-12-01

    The UNAVCO Facility is charged with implementing the campaign GPS component of the Plate Boundary Observatory (PBO) to support EarthScope investigators through a pool of approximately one hundred mobile GPS systems. In contrast to the PBO continuous GPS network, the PBO campaign systems are designed for temporary deployments with periods ranging from several minutes to several months per site. This allows researchers to conduct spatially and temporally focused investigations into a wide range of phenomena, including volcano monitoring, post-seismic deformation monitoring, and ground control for airborne LIDAR surveys. A standard PBO campaign system consists of a Topcon GB-1000 dual-frequency GPS receiver, a Topcon PG-A1 compact GPS antenna, an 18 Ah battery, cabling, a portable and waterproof Pelican case enclosure, and a Tech 2000 GPS antenna mast or tripod and tribrach. Available ancillary equipment includes solar panels, additional batteries, enclosures and mounting hardware. Communications equipment such as radio modems and cellular modems are also available to allow remote data retrieval during longer term deployments. We present an overview of the PBO campaign equipment available to investigators, technical specifications of the system, examples of current and planned EarthScope research projects utilizing the campaign equipment, and a hands-on demonstration of a PBO campaign system.

  19. Seismology: tectonic strain in plate interiors?

    Science.gov (United States)

    Calais, E; Mattioli, G; DeMets, C; Nocquet, J-M; Stein, S; Newman, A; Rydelek, P

    2005-12-15

    It is not fully understood how or why the inner areas of tectonic plates deform, leading to large, although infrequent, earthquakes. Smalley et al. offer a potential breakthrough by suggesting that surface deformation in the central United States accumulates at rates comparable to those across plate boundaries. However, we find no statistically significant deformation in three independent analyses of the data set used by Smalley et al., and conclude therefore that only the upper bounds of magnitude and repeat time for large earthquakes can be inferred at present.

  20. Microstructural change around grain boundary in polycrystalline IN100 during creep deformation

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Satoshi; Kubushiro, Keiji; Morishima, Keiko [Research Laboratory IHI Co. Ltd., Yokohama (Japan); Miura, Nobuhiro; Kondo, Yoshihiro [National Defense Academy, Yokosuka (Japan)

    2010-07-01

    The microstructural change of polycrystalline IN100 has been characterized. Tensile creep tests were conducted in the temperature range 950 to 1000 C at 74MPa and some tests were interrupted at 6, 16, 20, 30, 60 and 80% in creep life. Raft structure formed on (001) at the early stage of creep life in interior grains and grain boundaries were covered by {gamma}' phase. Creep fracture occurred at grain boundaries. In order to quantify the creep damage, average grain orientation spreads (GOS) of ruptured and interruptured specimens were measured. Average GOS of interrupted creep specimen after 6% of creep life consumption was about 0.6 degree and this value was almost constant until 80%, which did not show a correlation between average GOS and creep life consumption rate. Then we focused to the grain boundaries. The thickness of grain boundary {gamma}' phase increased as creep life consumption increased and the range of thickness was about 5-10{mu}m. The orientation of gamma prime phase at the grain boundary was same as that of interior of the grain and both of them were joined. Rotation angle of grain boundary {gamma}' was measured and there was a good correlation with creep life consumption. (orig.)

  1. Non-Similar Computational Solution for Boundary Layer Flows of Non-Newtonian Fluid from an Inclined Plate with Thermal Slip

    Directory of Open Access Journals (Sweden)

    SUBBARAO ANNASAGARAM

    2016-01-01

    Full Text Available The laminar boundary layer flow and heat transfer of Casson non-Newtonian fluid from an inclined (solar collector plate in the presence of thermal and hydrodynamic slip conditions is analysed. The inclined plate surface is maintained at a constant temperature. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite-difference scheme. Increasing velocity slip induces acceleration in the flow near the inclined plate surface. Increasing velocity slip consistently enhances temperatures throughout the boundary layer regime. An increase in thermal slip parameter strongly decelerates the flow and also reduces temperatures in the boundary layer regime. An increase in Casson rheological parameter acts to elevate considerably the velocity and this effect is pronounced at higher values of tangential coordinate. Temperatures are however very slightly decreased with increasing values of Casson rheological parameter.

  2. Analytical Solution of Forced-Convective Boundary-Layer Flow over a Flat Plate

    DEFF Research Database (Denmark)

    Mirgolbabaei, H.; Barari, Amin; Ibsen, Lars Bo

    2010-01-01

    In this letter, the problem of forced convection heat transfer over a horizontal flat plate is investigated by employing the Adomian Decomposition Method (ADM). The series solution of the nonlinear differential equations governing on the problem is developed. Comparison between results obtained...

  3. Analytical Solution of Forced-Convective Boundary-Layer Flow over a Flat Plate

    DEFF Research Database (Denmark)

    Mirgolbabaei, H.; Barari, Amin; Ibsen, Lars Bo;

    2010-01-01

    In this letter, the problem of forced convection heat transfer over a horizontal flat plate is investigated by employing the Adomian Decomposition Method (ADM). The series solution of the nonlinear differential equations governing on the problem is developed. Comparison between results obtained...

  4. The Plate Boundary Observatory Cascadia Network: Development and Installation of a Large Scale Real-time GPS Network

    Science.gov (United States)

    Austin, K. E.; Blume, F.; Berglund, H. T.; Feaux, K.; Gallaher, W. W.; Hodgkinson, K. M.; Mattioli, G. S.; Mencin, D.

    2014-12-01

    The EarthScope Plate Boundary Observatory (PBO), through a NSF-ARRA supplement, has enhanced the geophysical infrastructure in in the Pacific Northwest by upgrading a total of 282 Plate Boundary Observatory GPS stations to allow the collection and distribution of high-rate (1 Hz), low-latency (BGAN satellite communications systems has been conducted to support the Cascadia RT-GPS upgrades and the installation of three BGAN satellite fail over systems along the Cascadia margin will allow for the continuation of data flow in the event of a loss of primary communications during in a large geophysical event or other interruptions in commercial cellular networks. In summary, with these additional upgrades in the Cascadia region, the PBO RT-GPS network will increase to 420 stations. Upgrades to the UNAVCO data infrastructure included evaluation and purchase of the Trimble Pivot Platform, servers, and additional hardware for archiving the high rate data, as well as testing and implementation of GLONASS and Trimble RTX positioning on the receivers. UNAVCO staff is working closely with the UNAVCO community to develop data standards, protocols, and a science plan for the use of RT-GPS data.

  5. 考虑剪切效应有限变形粘弹性板的动力稳定性%Dynamic Stability of Viscoelastic Plates with Finite Deformation and Shear Effects

    Institute of Scientific and Technical Information of China (English)

    李晶晶; 程昌钧; 张能辉

    2002-01-01

    Based on Reddy' s theory of plates with higher-order shear deformations and the Boltzmann superposition principles, thegoverning equations were established for dynamic stability of viscoelastic plates with finite deformations taking account of shear ef-fects. The Galerkin method was applied to simplify the set of equations. The numerical methods in nonlinear dynamics were used tosolve the simplified system. It could be seen that there are plenty of dynamic properties for this kind of viscoelastic plates under trans-verse harmonic loads. The influences of the transverse shear deformations and material parameter on the dynamic behavior of nonlin-ear viscoelastic plates were investigated.

  6. Boundary integral equation methods in eigenvalue problems of elastodynamics and thin plates

    CERN Document Server

    Kitahara, M

    1985-01-01

    The boundary integral equation (BIE) method has been used more and more in the last 20 years for solving various engineering problems. It has important advantages over other techniques for numerical treatment of a wide class of boundary value problems and is now regarded as an indispensable tool for potential problems, electromagnetism problems, heat transfer, fluid flow, elastostatics, stress concentration and fracture problems, geomechanical problems, and steady-state and transient electrodynamics.In this book, the author gives a complete, thorough and detailed survey of the method. It pro

  7. On the Estimation of Spanwise Pressure Coherence of a Turbulent Boundary Layer over a Flat Plate

    NARCIS (Netherlands)

    Van der Velden, W.C.P.; Van Zuijlen, A.H.; De Jong, A.T.; Bijl, H.

    2014-01-01

    A Large Eddy Simulation (LES) with four different closure models are analyzed in OpenFOAM, an open source Computional Fluid Dynamics (CFD) package and validated for the determination of the streamwise and spanwise coherence length of the pressure field below a turbulent boundary layer at low

  8. Turbulent Friction in the Boundary Layer of a Flat Plate in a Two-Dimensional Compressible Flow at High Speeds

    Science.gov (United States)

    Frankl, F.; Voishel, V.

    1943-01-01

    In the present report an investigation is made on a flat plate in a two-dimensional compressible flow of the effect of compressibility and heating on the turbulent frictional drag coefficient in the boundary layer of an airfoil or wing radiator. The analysis is based on the Prandtl-Karman theory of the turbulent boundary later and the Stodola-Crocco, theorem on the linear relation between the total energy of the flow and its velocity. Formulas are obtained for the velocity distribution and the frictional drag law in a turbulent boundary later with the compressibility effect and heat transfer taken into account. It is found that with increase of compressibility and temperature at full retardation of the flow (the temperature when the velocity of the flow at a given point is reduced to zero in case of an adiabatic process in the gas) at a constant R (sub x), the frictional drag coefficient C (sub f) decreased, both of these factors acting in the same sense.

  9. "Discovering Plate Boundaries in Data-Rich Environments": Supporting Pre-service Teachers involvement in Unique Practices of Geosciences

    Science.gov (United States)

    Barrie, A. S.; Moore, J.

    2012-12-01

    plate tectonics using key scientific practices. As a result of the educational activities developed in this project, we will try help teachers to overcome their challenges and develop the pedagogical skills that novice teachers need to use to teach plate tectonics by focusing on key scientific practices with the help of previously-developed educational resources. Learning about the processes that occur at plate boundaries will help future teachers (and their students) understand natural disasters such as earthquakes and volcanoes. Furthermore, the study will have a significant, and broader, impact by 'teaching the teachers' and empowering novice teachers to overcome the challenges of reading maps and using argumentation in science classrooms.

  10. Development of low angle grain boundaries in lightly deformed superconducting niobium and their influence on hydride distribution and flux perturbation

    Science.gov (United States)

    Sung, Z.-H.; Wang, M.; Polyanskii, A. A.; Santosh, C.; Balachandran, S.; Compton, C.; Larbalestier, D. C.; Bieler, T. R.; Lee, P. J.

    2017-05-01

    This study shows that low angle grain boundaries (LAGBs) can be created by small 5% strains in high purity (residual resistivity ratio ≥ 200) superconducting radio frequency (SRF)-grade single crystalline niobium (Nb) and that these boundaries act as hydrogen traps as indicated by the distribution of niobium hydrides (Nb1-xHx). Nb1-xHx is detrimental to SRF Nb cavities due to its normal conducting properties at cavity operating temperatures. By designing a single crystal tensile sample extracted from a large grain (>5 cm) Nb ingot slice for preferred slip on one slip plane, LAGBs and dense dislocation boundaries developed. With chemical surface treatments following standard SRF cavity fabrication practice, Nb1-xHx phases were densely precipitated at the LAGBs upon cryogenic cooling (8-10 K/min). Micro-crystallographic analysis confirmed heterogeneous hydride precipitation, which included significant hydrogen atom accumulation in LAGBs. Magneto-optical imaging analysis showed that these sites can then act as sites for both premature flux penetration and eventually flux trapping. However, this hydrogen related degradation at LAGBs did not completely disappear even after an 800 °C/2 h anneal typically used for hydrogen removal in SRF Nb cavities. These findings suggest that hydride precipitation at an LAGB is facilitated by a non-equilibrium concentration of vacancy-hydrogen (H) complexes aided by mechanical deformation and the hydride phase interferes with the recovery process under 800 °C annealing.

  11. Water Release from Cold Serpentinized Forearc Mantle During Subduction Associated with Changes in Incoming Oceanic Plate Thermal Structure and Plate Boundary Kinematics: New Insights

    Science.gov (United States)

    Kirby, S. H.

    2015-12-01

    Kirby, Wang, and Brocher (Earth Planets and Space, 2014) recently showed how the change in kinematics of the California margin from subduction motion to continental transform motion with the birth and growth of the San Andreas Fault System (SAFS) beginning at about 33 Ma BP likely led to a warming of the former forearc mantle and the release of water by serpentinite dehydration. Such discharges from serpentinized mantle increase fluid pressures along the SAFS under the Coast Ranges and this gives insights into both the low sliding resistance for the SAFS and the mobilization and ascent of some serpentinized mantle peridotites through the crust. Thermal modeling by others has also shown that changes in the incoming plate age and subduction rate can also lead to warming of the forearc mantle during subduction. This development gives insights into the Mesozoic and Paleogene ages of emplacement of some, but not all, California serpentinites. Recent mineralogical and geochemical observations of serpentinized blocks in serpentinize mélange bodies in the San Francisco Bay Area (Uno and Kirby, 2015; Lewis and Kirby, 2015, this session) suggest that these rocks sustained multiple stages of serpentinization that are broadly consistent with the model of Kirby et al. (2014). Previous studies of localized late-stage silica-carbonate-water alteration of serpentinite bodies in California by carbonated water suggest that this alteration occurred largely in Neogene time when the highest rate of water release from the former forearc mantle probably happened. I also suggest that the occurrence of serpentinite belts emplaced in Cenozoic time during changing plate-boundary kinematics, such as the Cenozoic closing of the Tethys Ocean bordering Eurasia and arc reversal and decreasing convergence rates under the Greater Antilles, may give insights into the serpentinite belts in those regions.

  12. Motion of the Philippine Sea plate consistent with the NUVEL-1A model

    Science.gov (United States)

    Zang, Shao Xian; Chen, Qi Yong; Ning, Jie Yuan; Shen, Zheng Kang; Liu, Yong Gang

    2002-09-01

    We determine Euler vectors for 12 plates, including the Philippine Sea plate (PH), relative to the fixed Pacific plate (PA) by inverting the earthquake slip vectors along the boundaries of the Philippine Sea plate, GPS observed velocities, and 1122 data from the NUVEL-1 and the NUVEL-1A global plate motion model, respectively. This analysis thus also yields Euler vectors for the Philippine Sea plate relative to adjacent plates. Our results are consistent with observed data and can satisfy the geological and geophysical constraints along the Caroline (CR)-PH and PA-CR boundaries. The results also give insight into internal deformation of the Philippine Sea plate. The area enclosed by the Ryukyu Trench-Nankai Trough, Izu-Bonin Trench and GPS stations S102, S063 and Okino Torishima moves uniformly as a rigid plate, but the areas near the Philippine Trench, Mariana Trough and Yap-Palau Trench have obvious deformation.

  13. Hypersonic Laminar Boundary Layer Velocimetry with Discrete Roughness on a Flat Plate

    Science.gov (United States)

    Bathel, Brett; Danehy, Paul M.; Inman, Jennifer A.; Watkins, A. Neal; Jones, Stephen B.; Lipford, William E.; Goodman, Kyle Z.; Ivey, Christopher B.; Goyne, Christopher P.

    2010-01-01

    Laminar boundary layer velocity measurements are made on a 10-degree half-angle wedge in a Mach 10 flow. Two types of discrete boundary layer trips were used to perturb the boundary layer gas. The first was a 2-mm tall, 4-mm diameter cylindrical trip. The second was a scaled version of the Orbiter Boundary Layer Transition (BLT) Detailed Test Objective (DTO) trip. Both 1-mm and 2.5-mm tall BLT DTO trips were tested. Additionally, side-view and plan-view axial boundary layer velocity measurements were made in the absence of these tripping devices. The free-stream unit Reynolds numbers tested for the cylindrical trips were 1.7x10(exp 6)/m and 3.3x10(exp 6)/m. The free-stream unit Reynolds number tested for the BLT DTO trips was 1.7x10(exp 6)/m. The angle of attack was kept at approximately 5-degrees for most of the tests resulting in a Mach number of approximately 8.3. These combinations of unit Reynolds numbers and angle of attack resulted in laminar flowfields. To study the precision of the measurement technique, the angle of attack was varied during one run. Nitric-oxide (NO) molecular tagging velocimetry (MTV) was used to obtain averaged axial velocity values and associated uncertainties. These uncertainties are as low as 20 m/s. An interline, progressive scan CCD camera was used to obtain separate images of the initial reference and shifted NO molecules that had been tagged by the laser. The CCD configuration allowed for sub-microsecond sequential acquisition of both images. The maximum planar spatial resolution achieved for the side-view velocity measurements was 0.07-mm in the wall-normal direction by 1.45-mm in the streamwise direction with a spatial depth of 0.5-mm. For the plan-view measurements, the maximum planar spatial resolution in the spanwise and streamwise directions was 0.69-mm by 1.28-mm, respectively, with a spatial depth of 0.5-mm. Temperature sensitive paint (TSP) measurements are provided to compliment the velocity data and to provide further

  14. Hydromagnetic natural convection flow between vertical parallel plates with time-periodic boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Adesanya, S.O., E-mail: adesanyas@run.edu.ng [Department of Mathematical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Oluwadare, E.O. [Department of Mathematical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Falade, J.A., E-mail: faladej@run.edu.ng [Department of Physical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Makinde, O.D., E-mail: makinded@gmail.com [Faculty of Military Science, Stellenbosch University, Private Bag X2, Saldanha 7395 (South Africa)

    2015-12-15

    In this paper, the free convective flow of magnetohydrodynamic fluid through a channel with time periodic boundary condition is investigated by taking the effects of Joule dissipation into consideration. Based on simplifying assumptions, the coupled governing equations are reduced to a set of nonlinear boundary valued problem. Approximate solutions are obtained by using semi-analytical Adomian decomposition method. The effect of pertinent parameters on the fluid velocity, temperature distribution, Nusselt number and skin friction are presented graphically and discussed. The result of the computation shows that an increase in the magnetic field intensity has significant influence on the fluid flow. - Highlights: • The influence of magnetic field on the free convective fluid flow is considered. • The coupled equations are solved by using Adomian decomposition method. • The Adomian series solution agreed with previously obtained result. • Magnetic field decreases the velocity maximum but enhances temperature field.

  15. Force response of actively deformed polymer microdroplets: dependence on the solid/liquid boundary condition

    Science.gov (United States)

    Heppe, Jonas; McGraw, Joshua D.; Bennewitz, Roland; Jacobs, Karin

    2015-03-01

    In fluid dynamics, the solid/liquid boundary condition can play a major role in the flow behavior of a liquid. For example, in the dewetting of identical polymer films on weak slip or strong slip substrates, large qualitative and quantitative differences are observed. Therefore, when applying an external load to a liquid resting on such substrates, the measured reaction forces and the ensuing flow should also depend on the boundary condition. We present atomic force microscopy measurements in which the reaction force of a cantilever is measured as the tip pierces liquid polymer micron sized droplets and films. These indentations are done on substrates with tuned slip. Accessing the size, depth and rate dependence of the resulting force distance curves, we show an influence of the slip condition on the dissipated energy and adhesion.

  16. Dislocation-Mediated Deformation in Solid Langmuir Monolayers: Plastic Bending and Tilt Boundary.

    Science.gov (United States)

    Hatta, E

    2015-09-08

    The shear response of three types of textures (mosaic, striation, and stripe) in 10,12-pentacosadiynoic acid solid Langmuir monolayers has been investigated with Brewster angle microscopy. Low temperature mosaic textures respond to an applied stress elastically. Upon the application of shear the change of contrast appears in the form of propagation of fronts roughly perpendicularly to the shear direction within a single domain reversibly, while the domain shape keeps constant since it is presumably frozen kinetically. The striation and stripe textures at high temperatures show a viscoplastic behavior (plastic bending) in its rheological response, being consistent with the formation of a dislocation wall (tilt boundary) through dislocation dynamics (dislocation glide and climb). The stress-induced formation of a tilt boundary provides a manifestation of the collective motion of a number of dislocations.

  17. Effect of Boundary Conditions on the Back Face Deformations of Flat UHMWPE Panels

    Science.gov (United States)

    2014-12-01

    Zhang [2] carried out a numerical study of the effects of clamping type and clamping pressure on the ballistic performance of woven Kevlar , and found...effects of composite size were also studied. Singletary [5] studied the effects of boundary conditions and panel sizes on V50 for Kevlar KM2 fabric. The...on the BFD in flat UHMWPE panels. UHMWPE possesses high tenacity and high strength compared to Kevlar , as a result of which it is the material of

  18. The Plate-Joystick technique to reduce proximal humeral fractures and nonunions with a varus deformity through the extended deltoid-splitting approach.

    Science.gov (United States)

    Robinson, C Michael; Inman, Dominic; Phillips, Sally-Anne

    2011-10-01

    Fractures and nonunions in which there is a varus deformity of the humeral head producing posterinferior subluxation of the articular surface are increasingly recognized as an important subgroup of proximal humeral fractures. Operative open reduction and internal fixation of these injuries is often recommended when the varus deformity is severe. We describe a simple technique to assist in the open reduction and locking plate stabilization of this challenging and complex fracture subtype using tools and implants that are readily available in most modern orthopaedic trauma operating rooms.

  19. Mixed convection boundary layer flow past vertical flat plate in nanofluid:case of prescribed wall heat flux

    Institute of Scientific and Technical Information of China (English)

    R. TRˆIMBIT¸AS¸; T.GROSAN; I.POP

    2015-01-01

    An analysis is carried out to investigate the steady mixed convection bound-ary layer flow of a water based nanofluid past a vertical semi-infinite flat plate. Using an appropriate similarity transformation, the governing partial differential equations are transformed into the coupled, nonlinear ordinary (similar) differential equations, which are then solved numerically for the Prandtl number Pr = 6.2. The skin friction coeffi-cient, the local Nusselt number, and the velocity and temperature profiles are presented graphically and discussed. Effects of the solid volume fractionφand the mixed convection parameterλon the fluid flow and heat transfer characteristics are thoroughly examined. Different from an assisting flow, it is found that the solutions for an opposing flow are non-unique. In order to establish which solution branch is stable and physically realizable in practice, a stability analysis is performed.

  20. Double diffusive magnetohydrodynamic (MHD) mixed convective slip flow along a radiating moving vertical flat plate with convective boundary condition.

    Science.gov (United States)

    Rashidi, Mohammad M; Kavyani, Neda; Abelman, Shirley; Uddin, Mohammed J; Freidoonimehr, Navid

    2014-01-01

    In this study combined heat and mass transfer by mixed convective flow along a moving vertical flat plate with hydrodynamic slip and thermal convective boundary condition is investigated. Using similarity variables, the governing nonlinear partial differential equations are converted into a system of coupled nonlinear ordinary differential equations. The transformed equations are then solved using a semi-numerical/analytical method called the differential transform method and results are compared with numerical results. Close agreement is found between the present method and the numerical method. Effects of the controlling parameters, including convective heat transfer, magnetic field, buoyancy ratio, hydrodynamic slip, mixed convective, Prandtl number and Schmidt number are investigated on the dimensionless velocity, temperature and concentration profiles. In addition effects of different parameters on the skin friction factor, [Formula: see text], local Nusselt number, [Formula: see text], and local Sherwood number [Formula: see text] are shown and explained through tables.

  1. Development of Streamwise Counter-Rotating Vortices in Flat Plate Boundary Layer Pre-set by Leading Edge Patterns

    KAUST Repository

    Hasheminejad, S.M.

    2017-04-03

    Development of streamwise counter-rotating vortices induced by leading edge patterns with different pattern shape is investigated using hot-wire anemometry in the boundary layer of a flat plate. A triangular, sinusoidal and notched patterns with the same pattern wavelength λ of 15mm and the same pattern amplitude A of 7.5mm were examined for free-stream velocity of 3m/s. The results show a good agreement with earlier studies. The inflection point on the velocity profile downstream of the trough of the patterns at the beginning of the vortex formation indicates that the vortices non-linearly propagate downstream. An additional vortex structure was also observed between the troughs of the notched pattern.

  2. Mixed convection boundary layer flow over a moving vertical flat plate in an external fluid flow with viscous dissipation effect.

    Directory of Open Access Journals (Sweden)

    Norfifah Bachok

    Full Text Available The steady boundary layer flow of a viscous and incompressible fluid over a moving vertical flat plate in an external moving fluid with viscous dissipation is theoretically investigated. Using appropriate similarity variables, the governing system of partial differential equations is transformed into a system of ordinary (similarity differential equations, which is then solved numerically using a Maple software. Results for the skin friction or shear stress coefficient, local Nusselt number, velocity and temperature profiles are presented for different values of the governing parameters. It is found that the set of the similarity equations has unique solutions, dual solutions or no solutions, depending on the values of the mixed convection parameter, the velocity ratio parameter and the Eckert number. The Eckert number significantly affects the surface shear stress as well as the heat transfer rate at the surface.

  3. Double Diffusive Magnetohydrodynamic (MHD) Mixed Convective Slip Flow along a Radiating Moving Vertical Flat Plate with Convective Boundary Condition

    Science.gov (United States)

    Rashidi, Mohammad M.; Kavyani, Neda; Abelman, Shirley; Uddin, Mohammed J.; Freidoonimehr, Navid

    2014-01-01

    In this study combined heat and mass transfer by mixed convective flow along a moving vertical flat plate with hydrodynamic slip and thermal convective boundary condition is investigated. Using similarity variables, the governing nonlinear partial differential equations are converted into a system of coupled nonlinear ordinary differential equations. The transformed equations are then solved using a semi-numerical/analytical method called the differential transform method and results are compared with numerical results. Close agreement is found between the present method and the numerical method. Effects of the controlling parameters, including convective heat transfer, magnetic field, buoyancy ratio, hydrodynamic slip, mixed convective, Prandtl number and Schmidt number are investigated on the dimensionless velocity, temperature and concentration profiles. In addition effects of different parameters on the skin friction factor, , local Nusselt number, , and local Sherwood number are shown and explained through tables. PMID:25343360

  4. Fracture analysis of one-dimensional hexagonal quasicrystals: Researches of a finite dimension rectangular plate by boundary collocation method

    Energy Technology Data Exchange (ETDEWEB)

    Jiaxing, Cheng; Dongfa, Sheng [Southwest Forestry University, Yunnan (China)

    2017-05-15

    As an important supplement and development to crystallography, the applications about quasicrystal materials have played a core role in many fields, such as manufacturing and the space industry. Due to the sensitivity of quasicrystals to defects, the research on the fracture problem of quasicrystals has attracted a great deal of attention. We present a boundary collocation method to research fracture problems for a finite dimension rectangular one-dimensional hexagonal quasicrystal plate. Because mode I and mode II problems for one- dimensional hexagonal quasicrystals are like that for the classical elastic materials, only the anti-plane problem is discussed in this paper. The correctness of the present numerical method is verified through a comparison of the present results and the existing results. And then, the size effects on stress field, stress intensity factor and energy release rate are discussed in detail. The obtained results can provide valuable references for the fracture behavior of quasicrystals.

  5. The Fairway-Aotea Basin and the New Caledonia Trough, witnesses of the Pacific-Australian plate boundary evolution : from mid-Cretaceous cessation of subduction to Eocene subduction renewal

    Science.gov (United States)

    Collot, J.; Geli, L. B.; Lafoy, Y.; Sutherland, R.; Herzer, R. H.; Roest, W. R.

    2009-12-01

    The geodynamical history of the SW Pacific is controlled since the Mesozoic by the evolution of peri-Pacific subduction zones, in a trench retreat by slab roll-back process, which successively occurred along the Eastern Gondwana margin. In this context, most basins which formed after 45 Ma reached a stage of seafloor spreading, have recorded the inversions of the earth's magnetic field and present typical oceanic crust morphologies. By contrast, the New Caledonia and Fairway basins, which are narrower and present thick sedimentary covers have a less known and more controversial origin. Based on a regional geological synthesis and on interpretation of multichannel seismic reflection and refraction data, combined with drill hole data off New Zealand and a compilation of regional potential data, we distinguish 2 phases of the evolution of the Fairway-Aotea Basin (FAB) and the New Caledonia Trough (NCT), which reflect the evolution of the Gondwana-Pacific plate boundary: Phase 1: Mid Cretaceous formation of the FAB in a continental intra- or back- arc position of the Pacific-Gondwana subduction system. The formation of this shallow basin reflects the onset of continental breakup of the Eastern Gondwana margin during Cenomanian which was most probably caused by a dynamic change of the subduction zone through a « verticalization » of the slab. This event may be the result of the 99 Ma kinematic plate reorganization which probably led to subduction cessation along the Gondwana-Pacific plate boundary. A tectonic escape mechanism, in relation with the locking of the subduction zone by the Hikurangi Plateau, could also be responsible of the trench retreat leading to backarc extension. Phase 2: Regional Eocene-Oligocene uplift followed by rapid subsidence (3-4 km) of the system « Lord Howe Rise - FAB - Norfolk Ridge ». The structural style of this deformation leads us to suggest that detachment of the lower crust is the cause of subsidence. We therefore propose a model in

  6. Effects of crystal boundary gliding and dislocation on superplastic deformation of SiCw/6061 Al composite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    SiCw/6061Al composite was fabricated with squeeze casting method, hot extruded and superplastically tensile tested. At the temperature of 570  ℃and the strain rate of 2.0×10-3 s-1, an elongation of 280% was obtained. The change of grain shape, dislocation density and distribution was observed by TEM. The results show that during the superplastic deformation grain shape on the whole is unchanged, but the dislocation density and distribution vary quite a lot with the tensile action. Under the optimal straining conditions, dislocation mainly distributes along the grain boundary, which has an important effect on cooperative strain especially. When the strain magnitude is big enough, there appears stacking faults and twin crystals, which also has some effect on the cooperative strain.

  7. The Garzon fault: active southwestern boundary of the Caribbean plate in Colombia

    Science.gov (United States)

    Chorowicz, J.; Chotin, P.; Guillande, R.

    1996-03-01

    We propose active right-lateral strike-slip motion on the Garzon fault zone of the Neiva basin, Colombia, based on the identification of two active right-stepping releasing bend basins along the fault using stereoscopic analysis of 1/250000 SPOT images. The Garzon fault connects the Bocono-Pamplona-Guaicaramo fault zones of Venezuela and Colombia with the Romeral, Dolores and Guayaquil faults of Colombia. Together these faults form a continuous, active right-lateral fault between accreted terranes in northwestern South America and a more stable South America plate. We infer 5-km right-lateral offset of the Garzon fault based on the width of the Algeciras releasing bend basin.

  8. Discovering Plate Boundaries in Data-integrated Environments: Preservice Teachers' Conceptualization and Implementation of Scientific Practices

    Science.gov (United States)

    Sezen-Barrie, Asli; Moore, Joel; Roig, Cara E.

    2015-08-01

    Drawn from the norms and rules of their fields, scientists use variety of practices, such as asking questions and arguing based on evidence, to engage in research that will contribute to our understanding of Earth and beyond. In this study, we explore how preservice teachers' learn to teach scientific practices while teaching plate tectonic theory. In particular, our aim is to observe which scientific practices preservice teachers use while teaching an earth science unit, how do they integrate these practices into their lessons, and what challenges do they face during their first time teaching of an earth science content area integrated with scientific practices. The study is designed as a qualitative, exploratory case study of seven preservice teachers while they were learning to teach plate tectonic theory to a group of middle school students. The data were driven from the video records and artifacts of the preservice teachers' learning and teaching processes as well as written reflections on the teaching. Intertextual discourse analysis was used to understand what scientific practices preservice teachers choose to integrate into their teaching experience. Our results showed that preservice teachers chose to focus on four aspects of scientific practices: (1) employing historical understanding of how the theory emerged, (2) encouraging the use of evidence to build up a theory, (3) observation and interpretation of data maps, and (4) collaborative practices in making up the theory. For each of these practices, we also looked at the common challenges faced by preservice teachers by using constant comparative analysis. We observed the practices that preservice teachers decided to use and the challenges they faced, which were determined by what might have come as in their personal history as learners. Therefore, in order to strengthen preservice teachers' background, college courses should be arranged to teach important scientific ideas through scientific practices

  9. Interior Baja B.C. : Continuing Rotation on a Diffuse Plate Boundary

    Science.gov (United States)

    Symons, D. T.; Harris, M. J.; McCausland, P. J.; Blackburn, W. H.; Hart, C. J.

    2004-12-01

    Interior Baja B.C. - the Intermontane Belt (IMB) and Yukon-Tanana (YT) terranes of northwestern North America - provide a geological record of the complex interactions between the northeastern Pacific basin plates and craton. Geophysical evidence from earthquake seismology, gravity, global positioning system and heat flow data indicate motion of the IMB terranes toward the craton today. Paleomagnetic data show the YT terrane to be parautochthonous and part of the craton's ramp onto which the IMB terranes were obducted. Conversely the IMB terranes behaved as an allochthonous reasonably-coherent microplate with its own apparent polar wander path. Relative to the craton, the path dictates that: 1) from 0-54 Ma the IMB rotated steadily on the craton's ramp at 0.29±±0.11° /Ma or 16±6° clockwise (CW), consistent with Lithoprobe SNORCLE deep crustal seismic evidence for thin skinned tectonics; 2) from 54 to 102±14 Ma the IMB was offshore and was further rotated by 35±14° CW and translated northward by 8.3±7.0° (915±75 km), consistent with geological estimates for total dextral fault displacement and seafloor plate vectors; and 3) more speculatively, from Early Cretaceous to Early Jurassic, the IMB moved in concert with the craton off the western USA seaboard. This history fits with major geologic events such as extensive Eocene extension in southern British Columbia, development of the 1000 km-long Selwyn-Mackenzie orogenic arc in Yukon, YT terrane exposure on either side of the IMB, etc. Further it requires continuing crust-mantle interactions that extend some hundreds of kilometers into the craton today.

  10. Most-Critical Transient Disturbances in an Incompressible Flat-Plate Boundary Layer

    Science.gov (United States)

    Monschke, Jason; White, Edward

    2015-11-01

    Transient growth is a linear disturbance growth mechanism that plays a key role in roughness-induced boundary-layer transition. It occurs when superposed stable, non-orthogonal continuous spectrum modes experience algebraic disturbance growth followed by exponential decay. Algebraic disturbance growth can modify the basic state making it susceptible to secondary instabilities rapidly leading to transition. Optimal disturbance theory was developed to model the most-dangerous disturbances. However, evidence suggests roughness-induced transient growth is sub-optimal yet leads to transition earlier than optimal theory suggests. This research computes initial disturbances most unstable to secondary instabilities to further develop the applicability of transient growth theory to surface roughness. The main approach is using nonlinear adjoint optimization with solutions of the parabolized Navier-Stokes and BiGlobal stability equations. Two objective functions were considered: disturbance kinetic energy growth and sinuous instability growth rate. The first objective function was used as validation of the optimization method. Counter-rotating streamwise vortices located low in the boundary layer maximize the sinuous instability growth rate. The authors would like to acknowledge NASA and the AFOSR for funding this work through AFOSR Grant FA9550-09-1-0341.

  11. Bending and free vibration analysis of functionally graded plates using new eight-unknown shear deformation theory by finite-element method

    Science.gov (United States)

    Van Long, Nguyen; Quoc, Tran Huu; Tu, Tran Minh

    2016-12-01

    In this paper, a new eight-unknown shear deformation theory is developed for bending and free vibration analysis of functionally graded plates by finite-element method. The theory based on full 12-unknown higher order shear deformation theory simultaneously satisfies zeros transverse stresses at top and bottom surfaces of FG plates. A four-node rectangular element with 16 degrees of freedom per node is used. Poisson's ratios, Young's moduli, and material densities vary continuously in thickness direction according to the volume fraction of constituents which is modeled as power-law functions. Results are verified with available results in the literature. Parametric studies are performed for different power-law indices, side-to-thickness ratios.

  12. Creep deformation of grain boundary in a highly crystalline SiC fibre.

    Science.gov (United States)

    Shibayama, Tamaki; Yoshida, Yutaka; Yano, Yasuhide; Takahashi, Heishichiro

    2003-01-01

    Silicon carbide (SiC) matrix composites reinforced by SiC fibres (SiC/SiC composites) are currently being considered as alternative materials in high Ni alloys for high-temperature applications, such as aerospace components, gas-turbine energy-conversion systems and nuclear fusion reactors, because of their high specific strength and fracture toughness at elevated temperatures compared with monolithic SiC ceramics. It is important to evaluate the creep properties of SiC fibres under tensile loading in order to determine their usefulness as structural components. However, it would be hard to evaluate creep properties by monoaxial tensile properties when we have little knowledge on the microstructure of crept specimens, especially at the grain boundary. Recently, a simple fibre bend stress relaxation (BSR) test was introduced by Morscher and DiCarlo to address this problem. Interpretation of the fracture mechanism at the grain boundary is also essential to allow improvement of the mechanical properties. In this paper, effects of stress applied by BSR test on microstructural evolution in advanced SiC fibres, such as Tyranno-SA including small amounts of Al, are described and discussed along with the results of microstructure analysis on an atomic scale by using advanced microscopy.

  13. Numerical Investigation of Wall Cooling and Suction Effects on Supersonic Flat-Plate Boundary Layer Transition Using Large Eddy Simulation

    Directory of Open Access Journals (Sweden)

    Suozhu Wang

    2015-02-01

    Full Text Available Reducing friction resistance and aerodynamic heating has important engineering significance to improve the performances of super/hypersonic aircraft, so the purpose of transition control and turbulent drag reduction becomes one of the cutting edges in turbulence research. In order to investigate the influences of wall cooling and suction on the transition process and fully developed turbulence, the large eddy simulation of spatially evolving supersonic boundary layer transition over a flat-plate with freestream Mach number 4.5 at different wall temperature and suction intensity is performed in the present work. It is found that the wall cooling and suction are capable of changing the mean velocity profile within the boundary layer and improving the stability of the flow field, thus delaying the onset of the spatial transition process. The transition control will become more effective as the wall temperature decreases, while there is an optimal wall suction intensity under the given conditions. Moreover, the development of large-scale coherent structures can be suppressed effectively via wall cooling, but wall suction has no influence.

  14. MHD boundary layer slip flow and radiative nonlinear heat transfer over a flat plate with variable fluid properties and thermophoresis

    Directory of Open Access Journals (Sweden)

    S.K. Parida

    2015-12-01

    Full Text Available This work considers the two-dimensional steady MHD boundary layer flow of heat and mass transfer over a flat plate with partial slip at the surface subjected to the convective heat flux. The particular attraction lies in searching the effects of variable viscosity and variable thermal diffusivity on the behavior of the flow. In addition, non-linear thermal radiation effects and thermophoresis are taken into account. The governing nonlinear partial differential equations for the flow, heat and mass transfer are transformed into a set of coupled nonlinear ordinary differential equations by using similarity variable, which are solved numerically by applying Runge–Kutta fourth–fifth order integration scheme in association with quasilinear shooting technique. The novel results for the dimensionless velocity, temperature, concentration and ambient Prandtl number within the boundary layer are displayed graphically for various parameters that characterize the flow. The local skin friction, Nusselt number and Sherwood number are shown graphically. The numerical results obtained for the particular case are fairly in good agreement with the result of Rahman [6].

  15. Formation of diapiric structure in the deformation zone, central Indian Ocean: A model from gravity and seismic reflection data

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Rao, D.G.; Neprochnov, Y.P.

    Analyses of bathymetry, gravity and seismic reflection data of the diffusive plate boundary in the central Indian Ocean reveal a new kind of deformed structure besides the well-reported structures of long-wavelength anticlinal basement rises...

  16. Magmatism at the Eurasian–North American modern plate boundary: Constraints from alkaline volcanism in the Chersky Belt (Yakutia)

    Science.gov (United States)

    Tschegg, Cornelius; Bizimis, Michael; Schneider, David; Akinin, Vyacheslav V.; Ntaflos, Theodoros

    2011-01-01

    The Chersky seismic belt (NE-Russia) forms the modern plate boundary of the Eurasian−North American continental plate. The geodynamic evolution of this continent−continent setting is highly complex and remains a matter of debate, as the extent and influence of the Mid-Arctic Ocean spreading center on the North Asian continent since the Eocene remains unclear. The progression from a tensional stress regime to a modern day transpressional one in the Chersky seismic belt, makes the understanding even more complicated. The alkaline volcanism that has erupted along the Chersky range from Eocene through to the Recent can provide constraints on the geodynamic evolution of this continental boundary, however, the source and petrogenetic evolution of these volcanic rocks and their initiating mechanisms are poorly understood. We studied basanites of the central Chersky belt, which are thought to represent the first alkaline volcanic activity in the area, after initial opening of the Arctic Ocean basin. We present mineral and bulk rock geochemical data as well as Sr–Nd–Pb–Hf isotopes of the alkaline suite of rocks combined with new precise K–Ar and 40Ar/39Ar dating, and discuss an integrated tectono-magmatic model for the Chersky belt. Our findings show that the basanites were generated from a homogeneous asthenospheric mantle reservoir with an EM-1 isotopic flavor, under relatively ‘dry’ conditions at segregation depths around 110 km and temperatures of ~ 1500 °C. Trace element and isotope systematics combined with mantle potential temperature estimates offer no confirmation of magmatism related to subduction or plume activity. Mineral geochemical and petrographical observations together with bulk geochemical evidence indicate a rapid ascent of melts and high cooling rates after emplacement in the continental crust. Our preferred model is that volcanism was triggered by extension and thinning of the lithosphere combined with adiabatic upwelling of the

  17. Plate Boundary Observatory Strainmeter Recordings of The M6.0 August 24, 2014 South Napa Earthquake

    Science.gov (United States)

    Hodgkinson, Kathleen; Mencin, David; Phillips, David; Mattioli, Glen; Meertens, Charles

    2015-04-01

    The 2014 Mw6.0 South Napa earthquake nucleated at 11 km depth near the West Napa fault, one of a complex system of sub-parallel major right lateral faults north of San Francisco that together accommodate much of the relative motion between the Pacific and North American tectonic plates. The South Napa event was the largest to have shaken the San Francisco Bay Area (SFBA) in almost 25 years. A major goal of the NSF-funded EarthScope Plate Boundary Observatory (PBO), installed and maintained by UNAVCO, was to enable researchers to study the interaction between the faults that form a plate boundary zone, and in particular, to investigate the role that aseismic transients contribute to strain accumulation and release. To realize this goal, PBO includes borehole tensor strainmeters (BSMs) installed in several targeted regions, including on to the north and east of San Francisco. Two PBO BSMs have been operating in the SFBA since 2008: B057, north of San Francisco and 30 km from the epicenter, and B054, 3 km from the Hayward Fault and 40 km from the epicenter. We find the coseismic strains recorded by B057 are close to those predicted using elastic half-space dislocation theory and the seismically determined focal mechanism, while a more complicated variable slip model may be required for observations from B054. Months after the event, B057 continued to record a significant postseismic signal. In this presentation we document the coseismic signals recorded by the PBO BSMs and characterize the temporal behavior of the postseismic signal at B057. The PBO network includes over 1100 GPS, 75 BSMs, 79 seismometers and arrays of tiltmeters, pore pressure sensors and meteorological instrumentation. UNAVCO generates an Earthscope Level 2 processed strain time-series combined into areal and shear strains for the PBO BSM network; the raw data are available from the IRIS DMC in mSEED format. For events of interest, such as the South Napa earthquake, UNAVCO generates a 1-sps

  18. Lasting mantle scars lead to perennial plate tectonics

    OpenAIRE

    Heron, Philip J.; Pysklywec, Russell N.; Stephenson, Randell

    2016-01-01

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their p...

  19. BUOYANCY INSTABILITY IN THE NATURAL CONVECTION BOUNDARY LAYER AROUND A VERTICAL HEATED FLAT PLATE

    Institute of Scientific and Technical Information of China (English)

    颜大椿; 张汉勋

    2002-01-01

    A systematic research on the buoyancy instability in the natural convection boundary layer was conducted, including the basic characteristics such as its spectral components, wave length and velocity, the location of its critical layer,and amplitude distributions of the triple independent eigenmodes with the linear instability theory, the growth rates of its temperature and velocity fluctuations and the corresponding neutral curves for the buoyancy eigenmode were also obtained.Results indicated that the neutral curve of the velocity fluctuation had a nose shape consistent with that obtained in the numerical calculation, but for the temperature fluctuation, a ring-like region could be measured at a lower Grashof number before the nose-shaped main portion of the neutral curve.

  20. The role of viscoelasticity in subducting plates

    Science.gov (United States)

    Farrington, R. J.; Moresi, L.-N.; Capitanio, F. A.

    2014-11-01

    of tectonic plates into Earth's mantle occurs when one plate bends beneath another at convergent plate boundaries. The characteristic time of deformation at these convergent boundaries approximates the Maxwell relaxation time for olivine at lithospheric temperatures and pressures, it is therefore by definition a viscoelastic process. While this is widely acknowledged, the large-scale features of subduction can, and have been, successfully reproduced assuming the plate deforms by a viscous mechanism alone. However, the energy rates and stress profile within convergent margins are influenced by viscoelastic deformation. In this study, viscoelastic stresses have been systematically introduced into numerical models of free subduction, using both the viscosity and shear modulus to control the Maxwell relaxation time. The introduction of an elastic deformation mechanism into subduction models produces deviations in both the stress profile and energy rates within the subduction hinge when compared to viscous only models. These variations result in an apparent viscosity that is variable throughout the length of the plate, decreasing upon approach and increasing upon leaving the hinge. At realistic Earth parameters, we show that viscoelastic stresses have a minor effect on morphology yet are less dissipative at depth and result in an energy transfer between the energy stored during bending and the energy released during unbending. We conclude that elasticity is important during both bending and unbending within the slab hinge with the resulting stress loading and energy profile indicating that slabs maintain larger deformation rates at smaller stresses during bending and retain their strength during unbending at depth.

  1. Searching for Active Faults in the Western Eurasia-Nubia plate boundary

    Science.gov (United States)

    Antunes, Veronica; Custodio, Susana; Arroucau, Pierre; Carrilho, Fernando

    2016-04-01

    The repeated occurrence of large magnitude earthquakes in southwest Iberia in historical and instrumental times suggests the presence of active faults in the region. However, the region undergoes slow deformation, which results in low rates of seismic activity, and the location, dimension and geometry of active structures remains unsettled. We recently developed a new algorithm for earthquake location in 3D complex media with laterally varying interface depths, which allowed us to relocate 2363 events that occurred from 2007 to 2013. The method takes as inputs P- and S-wave catalog arrival times obtained from the Portuguese Meteorological Institute (IPMA, Instituto Portugues do Mar e da Atmosfera), for a study area defined by 8.5°W < lon < 5°W and 36° < lat < 37.5°. After relocation, we obtain a lineation of events in the Guadalquivir bank region, in the northern Gulf of Cadiz. The lineation defines a low-angle northward-dipping plane rooted at the base of the crust, which could indicate the presence of a major fault. We provide seismological evidence for the existence of this seemingly active structure based on earthquake relocations, focal mechanisms and waveform similarity between neighboring events.

  2. The Strengthening Effect of Phase Boundaries in a Severely Plastically Deformed Ti-Al Composite Wire

    Directory of Open Access Journals (Sweden)

    Tom Marr

    2014-02-01

    Full Text Available An accumulative swaging and bundling technique is used to prepare composite wires made of Ti and an Al alloy. These wires show reasonable higher yield stresses than expected from the pure material flow curves. The additional strengthening in the composite is analyzed using nanoindentation measurements, tensile testings and investigations of the microstructure. In addition, these properties are analyzed in relation to the fracture surface of the mechanically tested wires. Additional strengthening due to the presence of phase boundaries could be verified. Indications for residual stresses are found that cause a global hardness gradient from the center to the wire rim. Finally, the yield stress of the wires are calculated based on local hardness measurements.

  3. Interplay of Goos-Hänchen shift and boundary curvature in deformed microdisks.

    Science.gov (United States)

    Unterhinninghofen, Julia; Wiersig, Jan

    2010-08-01

    As the fabrication of wavelength-scale optical microcavities is becoming feasible, extended ray models which include first-order wave corrections have attracted considerable interest. By using such a model, we find an unexpected shift of phase-space structures in momentum direction which can be attributed to the Goos-Hänchen shift in position direction and the boundary curvature ("periodic orbit shift," POS); this shift is calculated analytically for a general cavity shape. By comparing it to wave calculations in the special case of a limaçon-shaped microcavity, it is shown that mode localization occurs on the shifted, rather than the original, phase-space structures. Comparing of our analytical result to literature data, we find good agreement, which suggests that the POS may be responsible for many cases of previously reported, but unexplained, mismatches between Husimi functions and the ray-dynamical phase space.

  4. Plate Margin Deformation and Active Tectonics Along the Northern Edge of the Yakutat Terrane in the Saint Elias Orogen, Alaska and Yukon, Canada

    Science.gov (United States)

    Bruhn, Ronald L.; Sauber, Jeanne; Cotton, Michele M.; Pavlis, Terry L.; Burgess, Evan; Ruppert, Natalia; Forster, Richard R.

    2012-01-01

    The northwest directed motion of the Pacific plate is accompanied by migration and collision of the Yakutat terrane into the cusp of southern Alaska. The nature and magnitude of accretion and translation on upper crustal faults and folds is poorly constrained, however, due to pervasive glaciation. In this study we used high-resolution topography, geodetic imaging, seismic, and geologic data to advance understanding of the transition from strike-slip motion on the Fairweather fault to plate margin deformation on the Bagley fault, which cuts through the upper plate of the collisional suture above the subduction megathrust. The Fairweather fault terminates by oblique-extensional splay faulting within a structural syntaxis, allowing rapid tectonic upwelling of rocks driven by thrust faulting and crustal contraction. Plate motion is partly transferred from the Fairweather to the Bagley fault, which extends 125 km farther west as a dextral shear zone that is partly reactivated by reverse faulting. The Bagley fault dips steeply through the upper plate to intersect the subduction megathrust at depth, forming a narrow fault-bounded crustal sliver in the obliquely convergent plate margin. Since . 20 Ma the Bagley fault has accommodated more than 50 km of dextral shearing and several kilometers of reverse motion along its southern flank during terrane accretion. The fault is considered capable of generating earthquakes because it is linked to faults that generated large historic earthquakes, suitably oriented for reactivation in the contemporary stress field, and locally marked by seismicity. The fault may generate earthquakes of Mw <= 7.5.

  5. Applying the digital-image-correlation technique to measure the deformation of an old building’s column retrofitted with steel plate in an in situ pushover test

    Indian Academy of Sciences (India)

    Shih-Heng Tung; Ming-Hsiang Shih; Wen-Pei Sung

    2014-06-01

    An in situ pushover test is carried out on an old building of Guan-Miao elementary school in south Taiwan. Columns of this building are seismically retrofitted with steel plate. The DIC (digital-image-correlation) technique is used to measure the deformation of the retrofitted column. The result shows that the DIC technique can be successfully applied to measure the relative displacement of the column. Additionally, thismethod leads to the measurement of relative displacements formany points on the column simultaneously. Hence, the column deformation curve, rotation and curvature can be determined using interpolation method. The resulting curvaturediagram reveals that the phenomenon of plastic hinge occurs at about 2% storey drift ratio, and that the DIC technique can be applied to measure column deformation in a full scale in situ test.

  6. Inferences of Integrated Lithospheric Strength from Plate-Scale Analyses of Deformation Observed in the Aegean-Anatolian Region and the Indian Ocean

    Science.gov (United States)

    Houseman, Gregory

    2016-04-01

    In the context of a comprehensive review of the rheology and strength of the lithosphere (Marine and Petroleum Geology, 2011, doi:10.1016/j.marpetgeo.2011.05.008), Evgene Burov described the difficulty of extrapolating rock deformation laws derived from laboratory experiments to the time and length scales that apply when the Earth's lithosphere is deformed. Not only does the extrapolation introduce a large uncertainty, but even the relative importance of different possible mechanisms of deformation may be uncertain. Even though lithospheric deformation has a strong conceptual and theoretical basis, it is therefore essential, as Burov argued, that deformation laws for the lithosphere must be calibrated by using observations of deformation that occurs on a lithospheric length scale and at geological strain rates. The influence of regionally varying factors like crustal thickness, geothermal gradient and tectonic environment may induce large variations in how rapidly the lithosphere may deform in response to an applied load, not least in the contrast from continent to ocean. Plates may be deformed by different loading mechanisms but, when deformation is distributed over a broad region, the strain-rate field may be approximately constant with depth and we may integrate the in-plane stress components across the thickness of the lithosphere to derive a depth-averaged constitutive law for the deformation. This approximation is the basis for the thin viscous sheet formulation of lithospheric deformation and, in combination with appropriate observations, it allows us to calibrate the integrated resistance to processes like regional extension or convergence. In this talk I will summarise what we learn about effective lithospheric rheology from two recent studies of the distribution and rates of diffuse deformation of the lithosphere in, firstly the Anatolian-Aegean region, and secondly the Central Indian Ocean. In the first case the distribution of deformation is consistent

  7. Seismotectonics of a diffuse plate boundary: Observations off the Sumatra-Andaman trench

    Science.gov (United States)

    Aderhold, K.; Abercrombie, R. E.

    2016-05-01

    The actively deforming Indo-Australian intraplate region off the Sumatra-Andaman trench hosted the largest strike-slip earthquake recorded by modern instruments, the 2012 Mw 8.6 Wharton Basin earthquake, closely followed by a Mw 8.2 aftershock. These two large events ruptured either parallel north-south trending faults or a series of north-south and nearly perpendicular east-west fault planes. No active east-west faults had been identified in the region prior to these earthquakes, and the seismic rupture for these two earthquakes extended past the 800°C isotherm for lithosphere of this age, deep into the oceanic mantle and possibly beyond the inferred transition to ductile failure. To investigate the seismic behavior of this region, we calculate moment tensors with teleseismic body waves for 6.0 ≤ Mw ≤ 8.0 intraplate strike-slip earthquakes. The centroid depths are located throughout the seismogenic mantle and could extend through the oceanic crust, but are generally well constrained by the 600°C isotherm and do not appear to rupture beyond the 800°C isotherm. We conclude that while many earthquakes are consistent with a thermal limit to depth, large magnitude earthquakes may be able to rupture typically aseismic zones. We also perform finite-fault modeling for Mw ≥ 7.0 earthquakes and find a slight preference for rupture on east-west oriented faults for the 2012 Mw 7.2 and 2005 Mw 7.2 earthquakes. This lends support for the presence of active east-west faults in this region, consistent with the majority of previously published models of the 2012 M8+ earthquakes.

  8. ADOPT: A tool for automatic detection of tectonic plates at the surface of convection models

    Science.gov (United States)

    Mallard, C.; Jacquet, B.; Coltice, N.

    2017-08-01

    Mantle convection models with plate-like behavior produce surface structures comparable to Earth's plate boundaries. However, analyzing those structures is a difficult task, since convection models produce, as on Earth, diffuse deformation and elusive plate boundaries. Therefore we present here and share a quantitative tool to identify plate boundaries and produce plate polygon layouts from results of numerical models of convection: Automatic Detection Of Plate Tectonics (ADOPT). This digital tool operates within the free open-source visualization software Paraview. It is based on image segmentation techniques to detect objects. The fundamental algorithm used in ADOPT is the watershed transform. We transform the output of convection models into a topographic map, the crest lines being the regions of deformation (plate boundaries) and the catchment basins being the plate interiors. We propose two generic protocols (the field and the distance methods) that we test against an independent visual detection of plate polygons. We show that ADOPT is effective to identify the smaller plates and to close plate polygons in areas where boundaries are diffuse or elusive. ADOPT allows the export of plate polygons in the standard OGR-GMT format for visualization, modification, and analysis under generic softwares like GMT or GPlates.

  9. Direct numerical simulation methods of hypersonic flat-plate boundary layer in thermally perfect gas

    Science.gov (United States)

    Jia, WenLi; Cao, Wei

    2014-01-01

    High-temperature effects alter the physical and transport properties of air such as vibrational excitation in a thermally perfect gas, and this factor should be considered in order to compute the flow field correctly. Herein, for the thermally perfect gas, a simple method of direct numerical simulation on flat-plat boundary layer is put forward, using the equivalent specific heat ratio instead of constant specific heat ratio in the N-S equations and flux splitting form of a calorically perfect gas. The results calculated by the new method are consistent with that by solving the N-S equations of a thermally perfect gas directly. The mean flow has the similarity, and consistent to the corresponding Blasius solution, which confirms that satisfactory results can be obtained basing on the Blasius solution as the mean flow directly in stability analysis. The amplitude growth curve of small disturbance is introduced at the inlet by using direct numerical simulation, which is consistent with that obtained by linear stability theory. It verified that the equation established and the simulation method is correct.

  10. Mathematical methods for elastic plates

    CERN Document Server

    Constanda, Christian

    2014-01-01

    Mathematical models of deformation of elastic plates are used by applied mathematicians and engineers in connection with a wide range of practical applications, from microchip production to the construction of skyscrapers and aircraft. This book employs two important analytic techniques to solve the fundamental boundary value problems for the theory of plates with transverse shear deformation, which offers a more complete picture of the physical process of bending than Kirchhoff’s classical one.   The first method transfers the ellipticity of the governing system to the boundary, leading to singular integral equations on the contour of the domain. These equations, established on the basis of the properties of suitable layer potentials, are then solved in spaces of smooth (Hölder continuous and Hölder continuously differentiable) functions.   The second technique rewrites the differential system in terms of complex variables and fully integrates it, expressing the solution as a combination of complex ana...

  11. Punctuated Neogene tectonics and stratigraphy of the African-Iberian plate-boundary zone: concurrent development of Betic-Rif basins (southern Spain, northern Morocco)

    NARCIS (Netherlands)

    Sissingh, W.

    2008-01-01

    This paper integrates the sequence stratigraphic and tectonic data related to the Neogene geodynamic and palaeogeographic development of the African-Iberian plate boundary zone between Spain and Morocco. Though the dating of individual tectonostratigraphic sequences and their delimiting sequence bou

  12. Punctuated Neogene tectonics and stratigraphy of the African-Iberian plate-boundary zone: concurrent development of Betic-Rif basins (southern Spain, northern Morocco)

    NARCIS (Netherlands)

    Sissingh, W.

    2008-01-01

    This paper integrates the sequence stratigraphic and tectonic data related to the Neogene geodynamic and palaeogeographic development of the African-Iberian plate boundary zone between Spain and Morocco. Though the dating of individual tectonostratigraphic sequences and their delimiting sequence bou

  13. Structural inheritance versus magmatic weakening: What controls the style of deformation at rift segment boundaries in the Gulf of California, Mexico?

    Science.gov (United States)

    Seiler, Christian; Gleadow, Andrew; Kohn, Barry

    2013-04-01

    Rifts are commonly segmented into several hundred kilometre long zones of opposing upper-plate transport direction with boundaries defined by accommodation and transfer zones. A number of such rift segments have been recognized in the Gulf of California, a youthful oceanic basin that is currently undergoing the rift-drift transition. However, detailed field studies have so far failed to identify suitable structures that could accommodate the obvious deformation gradients between different rift segments, and the nature of strain transfer at segment boundaries remains enigmatic. The Bocana transfer zone (BTZ) in central Baja California is a linear, WNW striking structural discontinuity separating two rift segments with different magnitudes and styles of extensional deformation. North of the BTZ, the Libertad fault is part of the Main Gulf Escarpment, which represents the breakaway fault that separates the Gulf of California rift to the east from the relatively stable western portion of the Baja peninsula. The N-striking Libertad escarpment developed during the Late Miocene (~10-8Ma) and exhibits a topographic relief of ca. 1,000m along a strike-length of ca. 50km. Finite displacement decreases from ~1000m in the central fault segment to ~500m further south, where the fault bends SE and merges with the BTZ. In the hanging wall of the Libertad fault, a series of W-tilted horsts are bound along their eastern margins by two moderate-displacement E-dipping normal faults. South of the BTZ, extension was much less than further north, which explains the comparatively subdued relief and generally shallower tilt of pre-rift strata in this area. The BTZ itself is characterized by two en echelon WNW-ESE striking dextral-oblique transfer faults with a significant down-to-the-NNE extensional component. Strain is transferred from the Libertad breakaway fault onto the transfer faults over a distance of >20km through a network of interacting normal, oblique and strike-slip faults

  14. Integration of the Plate Boundary Observatory and Existing GPS Networks in Southern California: A Multi Use Geodetic Network

    Science.gov (United States)

    Walls, C.; Blume, F.; Meertens, C.; Arnitz, E.; Lawrence, S.; Miller, S.; Bradley, W.; Jackson, M.; Feaux, K.

    2007-12-01

    The ultra-stable GPS monument design developed by Southern California Geodetic Network (SCIGN) in the late 1990s demonstrates sub-millimeter errors on long time series where there are a high percentage of observations and low multipath. Following SCIGN, other networks such as PANGA and BARGEN have adopted the monument design for both deep drilled braced monuments (DDBM = 5 legs grouted 10.7 meters into bedrock/stratigraphy) and short drilled braced monuments (SDBM = 4 legs epoxied 2 meters into bedrock). A Plate Boundary Observatory (PBO) GPS station consists of a "SCIGN" style monument and state of the art NetRS receiver and IP based communications. Between the years 2003-2008 875 permanent PBO GPS stations are being built throughout the United States. Concomitant with construction of the PBO the majority of pre-existing GPS stations that meet stability specifications are being upgraded with Trimble NetRS and IP based communications to PBO standards under the EarthScope PBO Nucleus project. In 2008, with completed construction of the Plate Boundary Observatory, more than 1100 GPS stations will share common design specifications and have identical receivers with common communications making it the most homogenous geodetic network in the World. Of the 875 total Plate Boundary Observatory GPS stations, 211 proposed sites are distributed throughout the Southern California region. As of August 2007 the production status is: 174 stations built (81 short braced monuments, 93 deep drilled braced monuments), 181 permits signed, 211 permits submitted and 211 station reconnaissance reports. The balance of 37 stations (19 SDBM and 18 DDBM) will be built over the next year from Long Valley to the Mexico border in order of priority as recommended by the PBO Transform, Extension and Magmatic working groups. Fifteen second data is archived for each station and 1 Hz as well as 5 Hz data is buffered to be triggered for download in the event of an earthquake. Communications

  15. FINITE ELEMENT ANALYSIS OF A VERTICAL RECTANGULAR PLATE COUPLED WITH AN UNBOUNDED FLUID DOMAIN ON ONE SIDE USING A TRUNCATED FAR BOUNDARY

    Institute of Scientific and Technical Information of China (English)

    PANI P. K.; BHATTACHARYYA S. K.

    2009-01-01

    The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin's theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark-b method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.

  16. The effect of inclination angle on the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries

    Science.gov (United States)

    Yuan, Lin; Jing, Peng; Shan, Debin; Guo, Bin

    2017-01-01

    Atomistic simulations were used to investigate the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries at 0.1 K. The calculated grain boundary energies of Σ3 asymmetric tilt grain boundaries corresponded well with the energies measured in experiments and predicted by the theoretical description. The Σ3 asymmetric tilt grain boundaries with low inclination angles were composed of a replication of twin boundary segments separated by small ledges. The results demonstrated that the combination effect of Schmid factor and non-Schmid factors could explain dislocations emission into grain 1 only in models with low inclination angles (Ф nanocrystalline materials and provide insights into the synthesis of nanocrystalline materials with superior strength and ductility.

  17. Coercivity enhancement of hot-deformed Nd-Fe-B magnets by the eutectic grain boundary diffusion process

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lihua [Elements Strategy Initiative Center for Magnetic Materials, National Institute of Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8577 (Japan); Sepehri-Amin, H.; Ohkubo, T. [Elements Strategy Initiative Center for Magnetic Materials, National Institute of Materials Science, Tsukuba 305-0047 (Japan); Yano, M.; Kato, A.; Shoji, T. [Toyota Motor Corporation, Advanced Material Engineering Div., Susono 410-1193 (Japan); Hono, K., E-mail: kazuhiro.hono@nims.go.jp [Elements Strategy Initiative Center for Magnetic Materials, National Institute of Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8577 (Japan)

    2016-05-05

    Nd-M (M = Al, Cu, Ga, Zn, Mn) alloys with compositions close to eutectic points were investigated as diffusion sources for the grain boundary diffusion process to hot-deformed Nd-Fe-B magnets. Coercivity enhancement was observed for most of the alloys. Among them, the sample processed with Nd{sub 90}Al{sub 10} exhibited the highest coercivity of 2.5 T at room temperature. However, the sample processed with Nd{sub 70}Cu{sub 30} exhibited the highest coercivity of 0.7 T at 200 {sup °}C. Microstructural observations using scanning transmission electron microscope (STEM) showed that nonferromagnetic Nd-rich intergranular phase envelops the Nd{sub 2}Fe{sub 14}B grains after the diffusion process. Abnormal grain growth and the dissolution of Al into the Nd{sub 2}Fe{sub 14}B grains were observed in the sample processed with Nd{sub 90}Al{sub 10}, which explains its inferior thermal stability of coercivity compared to the sample processed with Nd{sub 70}Cu{sub 30}. The coercivity enhancement and poor thermal stability of the coercivity of the Nd{sub 90}Al{sub 10} diffusion-processed sample are discussed based on microstructure studies by transmission electron microscopy. - Highlights: • Coercivity of hot-deformed Nd-Fe-B magnets is enhanced by the infiltration of various R-TM eutectic alloys. • The sample infiltrated with Nd{sub 90}Al{sub 10} shows the highest coercivity of 2.5 T at room temperature. • At 200 °C, Nd{sub 70}Cu{sub 30} diffusion-processed sample possesses the highest coercivity of 0.7 T.

  18. Pattern of seismic deformation in the Western Mediterranean

    Directory of Open Access Journals (Sweden)

    S. Pondrelli

    1999-06-01

    Full Text Available The seismic deformation of the Western Mediterranean was studied with the aim of defining the strain pattern that characterizes the Africa-Eurasia plate boundary in this area. Within different sections along the boundary the cumulative moment tensor was computed over 90 years of seismological data. The results were compared with NUVELlA plate motion model and geodetic data. A stable agreement was found along Northern Africa to Sicily, where only Africa and Eurasia plates are involved. In this zone it is evident that changes in the strike of the boundary correspond to variations in the prevailing geometry of deformation, tectonic features and in the percentage of seismic with respect to total expected deformation. The geometry of deformation of periadriatic sections (Central to Southern Apennines, Eastern Alps and the Eastern Adriatic area agrees well with VLBI measurements and with regional geological features. Seismicity seems to account for low rates, from 3% to 31%, of total expected deformation. Only in the Sicily Strait, characterized by extensional to strike slip deformation, does the ratio reach a higher value (79%. If the amount of deformation deduced from seismicity seems low, because 90 years are probably not representative of the recurrence seismic cycle of the Western Mediterranean, the strain pattern we obtain from cumulative moment tensors is more representative of the kinematics of this area than global plate motion models and better identifies lower scale geodynamic features.

  19. Relocating Seismicity on the Arctic Plate Boundary Using Teleseismic and Regional Phases and a Bayesian Multiple Event Locator

    Science.gov (United States)

    Gibbons, Steven J.; Dahl-Jensen, Trine; Kværna, Tormod; Larsen, Tine B.; Paulsen, Berit; Voss, Peter

    2016-04-01

    The tectonophysics of plate boundaries are illuminated by the pattern of seismicity - and the ability to locate seismic events accurately depends upon the number and quality of observations, the distribution of recording stations, and how well the traveltimes of seismic phases are modelled. The boundary between the Eurasian and North American plates between 70 and 84 degrees North hosts large seismic events which are well recorded teleseismically and many more events at far lower magnitudes that are well recorded only at regional distances. Existing seismic bulletins have considerable spread and bias resulting from limited station coverage and deficiencies in the velocity models applied; this is particularly acute for the lower magnitude events which may only be constrained by a small number of Pn and Sn arrivals. Over the past 15 years, there has been a significant improvement in the seismic network in the Arctic - a difficult region to instrument due to the harsh climate, a sparsity of quiet and accessible sites, and the expense and difficult logistics of deploying and maintaining stations. New deployments and upgrades to stations on Greenland, Svalbard, and the islands Jan Mayen, Hopen, and Bjørnøya have resulted in a sparse but stable regional seismic network which results in events down to magnitudes below 3 generating high quality Pn and Sn signals on multiple stations. A catalog of over 1000 events in the region since 1998 has been generated using many new phase readings on stations on both sides of the spreading ridge in addition to teleseismic P phases. The Bayesloc program, a Bayesian hierarchical multiple event location algorithm, has been used to relocate the full set of events iteratively and this has resulted in a significant reduction in the spread in hypocenter estimates for both large and small events. Whereas single event location algorithms minimize the vector of time residuals on an event-by-event basis, Bayesloc favours the hypocenters which

  20. A plate boundary earthquake record from a wetland adjacent to the Alpine fault in New Zealand refines hazard estimates

    Science.gov (United States)

    Cochran, U. A.; Clark, K. J.; Howarth, J. D.; Biasi, G. P.; Langridge, R. M.; Villamor, P.; Berryman, K. R.; Vandergoes, M. J.

    2017-04-01

    Discovery and investigation of millennial-scale geological records of past large earthquakes improve understanding of earthquake frequency, recurrence behaviour, and likelihood of future rupture of major active faults. Here we present a ∼2000 year-long, seven-event earthquake record from John O'Groats wetland adjacent to the Alpine fault in New Zealand, one of the most active strike-slip faults in the world. We linked this record with the 7000 year-long, 22-event earthquake record from Hokuri Creek (20 km along strike to the north) to refine estimates of earthquake frequency and recurrence behaviour for the South Westland section of the plate boundary fault. Eight cores from John O'Groats wetland revealed a sequence that alternated between organic-dominated and clastic-dominated sediment packages. Transitions from a thick organic unit to a thick clastic unit that were sharp, involved a significant change in depositional environment, and were basin-wide, were interpreted as evidence of past surface-rupturing earthquakes. Radiocarbon dates of short-lived organic fractions either side of these transitions were modelled to provide estimates for earthquake ages. Of the seven events recognised at the John O'Groats site, three post-date the most recent event at Hokuri Creek, two match events at Hokuri Creek, and two events at John O'Groats occurred in a long interval during which the Hokuri Creek site may not have been recording earthquakes clearly. The preferred John O'Groats-Hokuri Creek earthquake record consists of 27 events since ∼6000 BC for which we calculate a mean recurrence interval of 291 ± 23 years, shorter than previously estimated for the South Westland section of the fault and shorter than the current interseismic period. The revised 50-year conditional probability of a surface-rupturing earthquake on this fault section is 29%. The coefficient of variation is estimated at 0.41. We suggest the low recurrence variability is likely to be a feature of

  1. Joint inversion of local, regional and teleseismic data for crustal thickness in the Eurasia-Africa plate boundary region

    Science.gov (United States)

    Marone, Federica; van der Meijde, Mark; van der Lee, Suzan; Giardini, Domenico

    2003-08-01

    A new map for the Moho discontinuity (EAM02) in the Eurasia-Africa plate boundary region is presented. Reliable results have also been obtained for the southern and eastern Mediterranean Basin, the northern African coasts and the eastern Atlantic Ocean, regions only occasionally considered in studies on the Mediterranean region. The Moho topography model is derived from two independent sets of constraints. Information contained in the fundamental and higher-mode Rayleigh waves obtained from waveform modelling is used to constrain the Moho depth between estimates of crustal thickness taken from published reflection and refraction surveys, gravity studies and receiver function analysis. Strong lateral variations in the Moho topography have been observed in the Mediterranean Sea, confirming the complex evolution of this plate boundary region. In the west, the Moho discontinuity has been found at 15-20 km depth, suggesting extended and, at least in some locations, oceanic crust, while in the east the crust is on average 25-30 km thick. There it is interpreted either as Mesozoic oceanic or thinned Precambrian continental crust covered by thick sedimentary deposits. Standard continental crust (30-35 km) is observed along the eastern part of the northern African coast, while to the west a rapid change from a relatively deep Moho (down to 42 km) below the Atlas Mountain Range to the thin crust of the southwestern Mediterranean Sea has been found. The crust beneath the eastern North Atlantic Ocean can be up to 5 km thicker compared with standard oceanic crust (6 km). The crust has been interpreted to be heterogeneous as a consequence of irregular magma supply at the Mid-Atlantic ridge. In addition, serpentinization of the sub-Moho mantle could contribute to the imaging of apparently anomalous thick oceanic crust. In Europe, the presence of crustal roots (>45 km) beneath the major mountain belts has been confirmed, while thin crust (isostatic compensation at 60 km depth

  2. On the relationship between tectonic plates and thermal mantle plume morphology

    Science.gov (United States)

    Lenardic, A.; Kaula, W. M.

    1993-01-01

    Models incorporating plate-like behavior, i.e., near uniform surface velocity and deformation concentrated at plate boundaries, into a convective system, heated by a mix of internal and basal heating and allowing for temperature dependent viscosity, were constructed and compared to similar models not possessing plate-like behavior. The simplified numerical models are used to explore how plate-like behavior in a convective system can effect the lower boundary layer from which thermal plumes form. A principal conclusion is that plate-like behavior can significantly increase the temperature drop across the lower thermal boundary layer. This temperature drop affects the morphology of plumes by determining the viscosity drop across the boundary layer. Model results suggest that plumes on planets possessing plate-like behavior, e.g., the Earth, may differ in morphologic type from plumes on planets not possessing plate-like behavior, e.g., Venus and Mars.

  3. Upper plate deformation and seismic barrier in front of Nazca subduction zone : the Chololo Fault System and active tectonics along the Coastal Cordillera, southern Peru

    OpenAIRE

    Audin, Laurence; Lacan, P.; Tavera, H.; Bondoux, Francis

    2008-01-01

    The South America plate boundary is one of the most active subduction zone. The recent Mw=8.4 Arequipa 2001 earthquake ruptured the subduction plane toward the south over 400 km and stopped abruptly on the Ilo Peninsula. In this exact region, the subduction seismic crisis induced the reactivation of continental fault systems in the coastal area. We studied the main reactivated fault system that trends perpendicular to the trench by detailed mapping of fault related-geomorphic features. Also, ...

  4. 2D and 3D Ground Penetrating Radar monitoring of a reinforced concrete asphalt plate affected by mechanical deformation.

    Science.gov (United States)

    Bavusi, M.; Dumoulin, J.; Loperte, A.; Rizzo, E.; Soldovieri, F.

    2012-04-01

    The main facility of Hydrogeosite Laboratory of the Italian National Research Council (Marsico Nuovo, CNR) is a 3m x 7m x 10m reinforced concrete pool filled by siliceous sand designed for hydrologic experiments. One of its peculiarities is the possibility to vary the water table depth by using a proper hydraulic system [1]. In the framework of the FP7 ISTIMES project (Integrated System for Transport Infrastructure surveillance and Monitoring by Electromagnetic Sensing), a 3m x 3m layered structure has been purposely built and placed in the pool of the Hydrogeosite Laboratory with the aim to carry out a long term monitoring, by using jointly several electromagnetic sensing technologies, during two different phases simulating the rising of the water table and a mechanical solicitation. Several layers composed the structure from the top to the bottom, such as: 5 cm of asphalt; 5-10 cm of reinforced concrete; 20-25 cm of conglomerate, 55 cm of sand. Moreover, in the sand layer, three (metallic and plastic) pipes of different size were buried to simulate utilities. Ground Penetrating Radar (GPR) surveys were performed by using a the GSSI SIR 3000 system equipped with 400 MHz and 1500 MHz central frequency antennas. Surveys carried out by means of 400 MHz antenna allowed to detect and localize the three pipes (one in plastic and two in metal) and to investigate the effects of the sand water content on their radar signature. Surveys carried out by using 1500 MHz antenna were focused to characterize the shallower layers of the structure. The Hydrogeosite experiment consisted in following stages: • Arising of a water table by infiltration from the bottom; • Water gravity infiltration condescendingly; • Infiltration by peristaltic pump in the very shallow layers of the structure; • Water table drawdown; • Mechanical structure deformation; • Asphalt plate restoration after mechanical solicitation. After each stage a series of GPR surveys was performed. Moreover

  5. Jet-boundary and Plan-form Corrections for Partial-Span Models with Reflection-Plane, End-Plate, or No End-Plate in a Closed Circular Wind Tunnel

    Science.gov (United States)

    Sivells, James C; Deters, Owen J

    1946-01-01

    A method is presented for determining the jet-boundary and plan-form corrections necessary for application to test data for a partial-span model with a reflection plane, an end plate, or no end plate in a closed circular wind tunnel. Examples are worked out for a partial-span model with each of the three end conditions in the Langley 19-foot pressure tunnel and the corrections are applied to measured values of lift, drag, pitching-moment, rolling-moment, and yawing-moment coefficients.

  6. Progressive migration of slab break-off along the southern Tyrrhenian plate boundary: Constraints for the present day kinematics

    Science.gov (United States)

    Chiarabba, Claudio; Palano, Mimmo

    2017-04-01

    The Ionian subduction in the central Mediterranean, just 200 km wide, is one of the narrowest in the world. Its evolution has involved a progressive disruption of the subducting slab, contemporaneous to the retreat and step-wise opening of back-arc basins. In this study, we analyse velocity anomalies of the upper mantle, together with the most comprehensive set of earthquake locations and kinematic indicators available for Italy, to reconstruct the geodynamics and tectonic evolution of the Ionian subduction system. Along the Sicilian boundary, we identify an eastward migration of the slab edge with detachment of the Ionian oceanic lithosphere. We hypothesize that the progressive detachment of the slab took place along lithospheric transform faults of the Neo-Tethys Ocean. Among the main active kinematic elements of the Ionian accretionary wedge, we suggest that a ∼400-km-long and highly segmented shear zone formed by the Aeolian-Tindari-Letojanni fault system and the Ionian fault represents the surface expression of such a lithospheric tearing. The present day convergence between the Eurasian and African plates is accommodated both at the frontal thrust of the flexed Hyblean margin in southern Sicily and offshore along the Tyrrhenian Sea. Lithospheric bending favors the wedging of the mantle underneath northern Sicily, while magmatic fluids are channeled along slab tears.

  7. Seismic heating signatures in the Japan Trench subduction plate-boundary fault zone: evidence from a preliminary rock magnetic `geothermometer'

    Science.gov (United States)

    Yang, Tao; Dekkers, Mark J.; Zhang, Bo

    2016-04-01

    Frictional heating during earthquake rupture reveals important information on earthquake mechanisms and energy dissipation. The amo