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Sample records for pacific plate interface

  1. Faulting within the Pacific plate at the Mariana Trench: Implications for plate interface coupling

    E-print Network

    Faulting within the Pacific plate at the Mariana Trench: Implications for plate interface coupling the incoming Pacific plate at the Mariana subduction trench to understand stresses within the bending plate below the Moho. At the Southern Mariana Trench, extensional earthquakes continue to 5 km below the Moho

  2. Faulting within the Pacific plate at the Mariana Trench: Implications for plate interface coupling and subduction of hydrous minerals

    NASA Astrophysics Data System (ADS)

    Emry, Erica L.; Wiens, Douglas A.; Garcia-Castellanos, Daniel

    2014-04-01

    We investigate faulting within the incoming Pacific plate at the Mariana subduction trench to understand stresses within the bending plate, regional stresses acting upon the plate interface, and the extent of possible faulting-induced mantle serpentinization. We determine accurate depths by inverting teleseismic P and SH waveforms for earthquakes occurring during 1990-2011 with Global Centroid Moment Tensor (GCMT) solutions. For earthquakes with Mw 5.0+, we determine centroid depths and source time functions and refine the fault parameters. Results from Central Mariana indicate that all earthquakes are extensional and occur at centroid depths down to 11 km below the Moho. At the Southern Mariana Trench, extensional earthquakes continue to 5 km below the Moho. One compressional earthquake at 34 km below the seafloor suggests stronger plate interface coupling here. In addition, we model the stress distribution within the Pacific plate along two bathymetric profiles extending seaward from the Mariana subduction trench axis to better understand whether our earthquake depth solutions match modeled scenarios for plate bending under applied external forces. Results from our flexure models match the locations of extensional and compressional earthquakes and suggest that the Pacific plate at Southern Mariana is experiencing larger, compressional stresses, possibly due to greater interplate coupling. Additionally, we conclude that if extensional faulting promotes the infiltration of water into the subducting plate mantle, then the top 5-15 km of the Pacific plate mantle are partially serpentinized, and a higher percentage of serpentinization is located near the Central Mariana trench where extensional events extend deeper.

  3. Plate kinematics in the western Pacific derived from geodetic observations

    E-print Network

    Tregoning, Paul

    Tectonophysics: Plate motions­present and recent (3040), 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); KEYWORDS: GPS, North Bismarck Plate, Australian Plate, Pacific Plate, tectonic spanning the Australian Plate and the western Pacific region to derive new tectonic models of the motions

  4. ``Plate-like'' subsidence of the East Pacific RiseSouth Pacific superswell system

    E-print Network

    Watts, A. B. "Tony"

    ``Plate-like'' subsidence of the East Pacific Rise­­South Pacific superswell system J. K. Hillier significantly, the superswell appears to be part of a large-scale, ``plate-like,'' subsidence that extends to the EPR crest, rather than an isolated shallowing that reverses the subsidence and causes uplift. We

  5. Physics-Based 3-D Simulation for Earthquake Generation Cycles at Plate Interfaces in Subduction Zones

    NASA Astrophysics Data System (ADS)

    Hashimoto, Chihiro; Fukuyama, Eiichi; Matsu'ura, Mitsuhiro

    2014-08-01

    The generation of interplate earthquakes can be regarded as a process of tectonic stress accumulation and release, driven by relative plate motion. We completed a physics-based simulation system for earthquake generation cycles at plate interfaces in the Japan region, where the Pacific plate is descending beneath the North American and Philippine Sea plates, and the Philippine Sea plate is descending beneath the North American and Eurasian plates. The system is composed of a quasi-static tectonic loading model and a dynamic rupture propagation model, developed on a realistic 3-D plate interface model. The driving force of the system is relative plate motion. In the quasi-static tectonic loading model, mechanical interaction at plate interfaces is rationally represented by the increase of tangential displacement discontinuity (fault slip) across them on the basis of dislocation theory for an elastic surface layer overlying Maxwell-type viscoelastic half-space. In the dynamic rupture propagation model, stress changes due to fault slip motion on non-planar plate interfaces are evaluated with the boundary integral equation method. The progress of seismic (dynamic) or aseismic (quasi-static) fault slip on plate interfaces is governed by a slip- and time-dependent fault constitutive law. As an example, we numerically simulated earthquake generation cycles at the source region of the 1968 Tokachi-oki earthquake on the North American-Pacific plate interface. From the numerical simulation, we can see that postseismic stress relaxation in the asthenosphere accelerates stress accumulation in the source region. When the stress state of the source region is close to a critical level, dynamic rupture is rapidly accelerated and develops over the whole source region. When the stress state is much lower than the critical level, the rupture is not accelerated. This means that the stress state realized by interseismic tectonic loading essentially controls the subsequent dynamic rupture process.

  6. Plate geometry and kinematics modeling to explain South Central Pacific volcanism and plate re-organization

    NASA Astrophysics Data System (ADS)

    Clouard, Valerie; Gerbault, Muriel

    2010-05-01

    We present here a model applied to the Pacific plate for a mechanism governing plate motion related to the plate geometry and kinematics. We start from the observation that from the Kermadec Tonga trench to the Easter microplate, a group of recent and presumed non-deep Pacific hotspots forms a wide east-west channel, and hypothesize that this is not a coincidence. We develop plane strain numerical models of an area corresponding to the Pacific plate from the mid-oceanic ridge to the subduction zone under the Australian plate, with differential velocities applied on the northern and southern part of the plate because of absolute trench motions. Our 2D models indicate a shear band, associated to a change from compressional stresses to the south to tensional stresses to the north, which develop after 10 Myr between the Australian plate corner and the Easter microplate. We propose that the South Central Pacific (SCP) intraplate volcanism is related to this process, and may represent the first step of a future plate re-organization, which will eventually break the Pacific plate in a southern and a northern plate due to intraplate stresses. Lithospheric extension associated with a fertile mantle source is necessary for the presence hotspots when these are not related to a deep mantle plume. To fully explain the SCP volcanism, we show that there is no relation between present-day SCP and the old Northwestern Pacific volcanism, except that it was created over the same mantle region before 70Ma, which represents the very fertile mantle needed.

  7. Geodetic Evidence of Post-2011 Acceleration of the Pacific Plate

    NASA Astrophysics Data System (ADS)

    Heki, K.; Mitsui, Y.

    2014-12-01

    Oceanic plates may accelerate after large inter-plate earthquakes (Anderson, Science 1975). This was indirectly substantiated by Heki and Mitsui (EPSL 2013), who analyzed crustal deformation of an island arc after megathrust earthquakes. Here we show direct evidence of postseismic acceleration of the Pacific Plate from the data of a Global Navigation Satellite System (GNSS) station on the Minami-torishima (Marcus) Island ~2000 km off the Pacific coast of Japan. Heki and Mitsui (2013) found the enhancement of the inter-plate coupling in NE Japan on segments adjacent to those ruptured in the 2003 Tokachi-Oki (Mw8.0) and the 2011 Tohoku-Oki (Mw9.0) earthquakes. They inferred that the subduction of the Pacific Plate slab significantly accelerated after these earthquakes. During interseismic periods, the balance between the down-dip (slab pull and ridge push) and up-dip (viscous traction and interplate coupling) forces realizes convergence rate constant over geological timescales. A megathrust event reduces interplate coupling, and the down-dip forces temporarily exceed the other. The accelerated subduction realizes under the new balance and continues until the interplate coupling recovers. In the Marcus Island, the closest island on the Pacific Plate to the Japan Trench, continuous GNSS observations started in 2002, and showed linear movement toward WNW of ~7.7 cm/year (in the nnr-NUVEL1 frame). This station showed coseismic jump of ~1 cm toward the epicenter in the 2011 Tohoku-oki earthquake. At the same time, the velocity showed distinct increase of ~10 percent without changing the azimuth, resulting in post-2011 speed of ~8.5 cm/year. This is difficult to explain with a simple postseismic viscous relaxation in a stratified earth, and would be the direct evidence of the postseismic acceleration of the Pacific Plate. Such an acceleration is, however, not seen in Hawaii, ~6000 km away from the fault.

  8. Pacific trench motions controlled by the asymmetric plate configuration

    E-print Network

    Buck, Roger

    Pacific trench motions controlled by the asymmetric plate configuration Thorsten J. Nagel,1 William; accepted 29 February 2008; published 23 May 2008. [1] We present a novel explanation for absolute trench of a simple finite difference scheme to estimate the effect on trench motion velocities. The hypothesis

  9. Fast Paleogene Motion of the Pacific Hotspots from Revised Global Plate Circuit Constraints

    NASA Technical Reports Server (NTRS)

    Raymond, C.; Stock, J.; Cande, S.

    2000-01-01

    Major improvements in late Cretaceous-early Tertiary Pacific-Antarctica plate reconstructions, and new East-West Antarctica rotations, allow a more definitive test of the relative motion between hotspots using global plate circuit reconstructions with quantitative uncertainties.

  10. Missing western half of the Pacific Plate: Geochemical nature of the Izanagi-Pacific Ridge interaction with a stationary boundary between the Indian and Pacific mantles

    NASA Astrophysics Data System (ADS)

    Miyazaki, Takashi; Kimura, Jun-Ichi; Senda, Ryoko; Vaglarov, Bogdan S.; Chang, Qing; Takahashi, Toshiro; Hirahara, Yuka; Hauff, Folkmar; Hayasaka, Yasutaka; Sano, Sakae; Shimoda, Gen; Ishizuka, Osamu; Kawabata, Hiroshi; Hirano, Naoto; Machida, Shiki; Ishii, Teruaki; Tani, Kenichiro; Yoshida, Takeyoshi

    2015-09-01

    The source mantle of the basaltic ocean crust on the western half of the Pacific Plate was examined using Pb-Nd-Hf isotopes. The results showed that the subducted Izanagi-Pacific Ridge (IPR) formed from both Pacific (180-˜80 Ma) and Indian (˜80-70 Ma) mantles. The western Pacific Plate becomes younger westward and is thought to have formed from the IPR. The ridge was subducted along the Kurile-Japan-Nankai-Ryukyu (KJNR) Trench at 60-55 Ma and leading edge of the Pacific Plate is currently stagnated in the mantle transition zone. Conversely, the entire eastern half of the Pacific Plate, formed from isotopically distinct Pacific mantle along the East Pacific Rise and the Juan de Fuca Ridge, largely remains on the seafloor. The subducted IPR is inaccessible; therefore, questions regarding which mantle might be responsible for the formation of the western half of the Pacific Plate remain controversial. Knowing the source of the IPR basalts provides insight into the Indian-Pacific mantle boundary before the Cenozoic. Isotopic compositions of the basalts from borehole cores (165-130 Ma) in the western Pacific show that the surface oceanic crust is of Pacific mantle origin. However, the accreted ocean floor basalts (˜80-70 Ma) in the accretionary prism along the KJNR Trench have Indian mantle signatures. This indicates the younger western Pacific Plate of IPR origin formed partly from Indian mantle and that the Indian-Pacific mantle boundary has been stationary in the western Pacific at least since the Cretaceous.

  11. New Reference Models for Pacific Absolute Plate Motion

    NASA Astrophysics Data System (ADS)

    Wessel, P.

    2012-12-01

    Absolute plate motion (APM) models are commonly derived by assuming that age-progressive seamount chains represent the surface expressions of mantle plumes; the chain geometries thus record the relative motion between plumes and plates. Traditionally, plumes have been assigned zero motion (i.e., the fixed hotspot hypothesis), and with this assumption the trails directly reflect plate motion. However, since the early 1970s arguments from sedimentary facies and marine magnetics have been marshaled against the fixity of hotspots, perhaps culminating with more recent and direct inferences of anomalous paleolatitudes for several seamounts in both the Emperor and Louisville chains. These data can broadly be explained by drifting plumes, but paleomagnetic data remain scarce and may allow for some true polar wander; furthermore, several age progressions are incomplete or inconsistent and the present locations of some hotspots are uncertain. Finally, APM models with moving hotspots derive largely from mantle flow modeling whose predictions do not match observations directly. Here, I present new absolute plate motion models for the Pacific plate back to 150 Ma. The first model assumes fixed hotspots and is meant to serve as a reference model representing the classic fixed hotspot hypothesis. It is an updated version of the Wessel and Kroenke [2008] model but now including all available chains, recently published age data and processed using improved modeling techniques. The second model uses the same data but also attempts to honor available data on hotspot mobility. It is intended to be a "work in progress" model that will be updated as additional paleolatitude or age data become available. These models can serve as test beds for tectonic hypothesis and be used to identify seamount chain segments where additional paleomagnetic or age observations would have the most impact.

  12. Circum-arctic plate accretion - Isolating part of a pacific plate to form the nucleus of the Arctic Basin

    USGS Publications Warehouse

    Churkin, M., Jr.; Trexler, J.H., Jr.

    1980-01-01

    A mosaic of large lithospheric plates rims the Arctic Ocean Basin, and foldbelts between these plates contain numerous allochthonous microplates. A new model for continental drift and microplate accretion proposes that prior to the late Mesozoic the Kula plate extended from the Pacific into the Arctic. By a process of circumpolar drift and microplate accretion, fragments of the Pacific basin, including parts of the Kula plate, were cut off and isolated in the Arctic Ocean, the Yukon-Koyukuk basin in Alaska, and the Bering Sea. ?? 1980.

  13. Explosive bonding of plates with diffusion barrier interfaces

    NASA Astrophysics Data System (ADS)

    Joshi, V. S.; Banks, M. L.; Krebsbach, J.

    2000-04-01

    Composite plates, with and without, "waves" were made using improved explosive welding techniques. Oriented heat treatment of one surface of a steel-titanium composite introduces brittle intermetallic material at the specific interface. Currently, we are investigating methods to minimize this layer. While "waveless" interfaces revealed minimum intermetallic material; failure of the bond during ballistic impact necessitated production of a semi-compatible diffusion barrier using a fine layer of pure metal. Methods of producing composite plates with different interlayer materials and the effect of variables in optimizing the bond quality is presented.

  14. Explosive Bonding of Plates with Diffusion Barrier Interfaces

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant; Banks, Marvin; Krebsbach, John

    1999-06-01

    Composite plates, with and without, “waves” were made using improved explosive welding techniques. Oriented heat treatment of one surface of a steel-titanium composite introduces brittle intermetallic material at the specific interface. Currently, we are investigating methods to minimize this layer. While “waveless” interfaces revealed minimum intermetallic material; failure of the bond during ballistic impact necessitated production of a semi-compatible diffusion barrier using a fine layer of pure metal. Methods of producing composite plates with different interlayer materials and the effect of variables in optimizing the bond quality will be presented.

  15. Plate motion controls on back-arc spreading. [Cenozoic movement in Western Pacific

    NASA Technical Reports Server (NTRS)

    Fein, J. B.; Jurdy, D. M.

    1986-01-01

    The motions of the subducting and the overriding plates influence the spatial and temporal distribution of back-arc spreading. Cenozoic plate motions in hot spot-fixed and no-net-rotation reference frames were studied with attention to correlations between changes in motion and episodes of back-arc spreading in the western Pacific. The results suggest that major back-arc opening occurs when both the overriding plate retreats from the trench in an absolute sense and the subducting plate undergoes a significant speed-up. Neither phenomenon alone is sufficient to initiate spreading. Three major plate velocity increases can be identified in the Cenozoic: (1) the Pacific plate 5-9 Ma; (2) the Indian plate at 27 Ma; and (3) the Pacific plate at 43 Ma, due to its shift from northerly to more westerly motion. At the present time, the Indian and Philippine are the only overriding plates that are retreating from their Pacific trenches and back-arc spreading occurs only on these two retreating plates. Although the Indian plate has been retreating for at least 25 Ma, back-arc spreading began only following the Pacific plate speed-up 5-9 Ma. Earlier, during the Indian plate speed-up, no overriding plates were retreating strongly and no back-arc spreading epsiodes are preserved from this time. For the earliest Pacific plate shift at 43 Ma, the Eurasian plate was not advancing, thus creating the only favorable plate kinematic conditions in the Cenozoic for back-arc basin formation in this region. It is unclear whether extension in the Japan Sea is a result of these conditions.

  16. Supraslab earthquakes above the Pacific-plate slab in NE Japan: A possible graveyard of detached seamounts and volcanic ridges?

    NASA Astrophysics Data System (ADS)

    Kirby, S.; Okada, T.; Uchida, N.; Hasegawa, A.; Matsuzawa, T.; Hino, R.

    2005-12-01

    Double-difference relocations of interplate thrust and intraslab earthquakes at depths greater than 35 km under NE Japan indicate that many clusters of earthquakes occur above the interplate thrust zone and hence are no longer part of the sinking Pacific-plate slab. The best examples of such clusters are found at depths of 40 to 60 km near the depth limit of interplate thrust earthquake activity and near the intersection of the forearc Moho with the plate interface. In some clusters, small repeating earthquakes occur on the plate interface below the supraslab clusters. The largest of these clusters have earthquakes that are as much as 25 km shallower than the plate boundary and extend as much as several tens of km in the down-dip direction. Offshore multi-beam sonar bathymetry shows seafloor relief that is dominated by seamounts and guyots, representing Cretaceous intraplate volcanic activity. The Japan inner trench slope is marked by many re-entrants that record past seamount-forearc collisions. Supraslab earthquake clusters may represent earthquake activity inside seamounts that have detached from the underlying Pacific plate along the original sedimented seafloor on which these intraplate shield volcanoes were built. If this interpretation is correct, then supraslab earthquakes may represent a unique cumulative record of past seamount subduction.

  17. Pulsed-echo interface wave characterization of bolted plates

    NASA Technical Reports Server (NTRS)

    Turner, T. M.; Claus, R. O.; Ocheltree, S. L.

    1981-01-01

    Ultrasonic waves which propagate along the plane boundary separating two solid substrates were used to characterize aluminum and titanium plates adhesively bonded and bolted together. Wave pulses were used to produce interface waves between the aluminum and a Ti-6Al-4V titanium alloy bar by normal mode conversion. Interface wave reflections from bolt holes drilled through the interface were reconverted to surface wave pulses and detected by the same wedge by standard pulse-echo techniques. Time of flight measurements indicate that the reflected waves are a supersonic of longitudinal modes and circularly symmetric waves that propagate around the bolt hole.

  18. Laser Shockwave Technique For Characterization Of Nuclear Fuel Plate Interfaces

    SciTech Connect

    James A. Smith; Barry H. Rabin; Mathieu Perton; Daniel Lévesque; Jean-Pierre Monchalin; Martin Lord

    2012-07-01

    The US National Nuclear Security Agency is tasked with minimizing the worldwide use of high-enriched uranium. One aspect of that effort is the conversion of research reactors to monolithic fuel plates of low-enriched uranium. The manufacturing process includes hot isostatic press bonding of an aluminum cladding to the fuel foil. The Laser Shockwave Technique (LST) is here evaluated for characterizing the interface strength of fuel plates using depleted Uranium/Mo foils. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves and is therefore well adapted to the quality assurance of this process. Preliminary results show a clear signature of well-bonded and debonded interfaces and the method is able to classify/rank the bond strength of fuel plates prepared under different HIP conditions.

  19. Laser shockwave technique for characterization of nuclear fuel plate interfaces

    SciTech Connect

    Perton, M.; Levesque, D.; Monchalin, J.-P.; Lord, M.; Smith, J. A.; Rabin, B. H.

    2013-01-25

    The US National Nuclear Security Agency is tasked with minimizing the worldwide use of high-enriched uranium. One aspect of that effort is the conversion of research reactors to monolithic fuel plates of low-enriched uranium. The manufacturing process includes hot isostatic press bonding of an aluminum cladding to the fuel foil. The Laser Shockwave Technique (LST) is here evaluated for characterizing the interface strength of fuel plates using depleted Uranium/Mo foils. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves and is therefore well adapted to the quality assurance of this process. Preliminary results show a clear signature of well-bonded and debonded interfaces and the method is able to classify/rank the bond strength of fuel plates prepared under different HIP conditions.

  20. Relative motions of the Australian, Pacific and Antarctic plates estimated by the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Larson, Kristine M.; Freymueller, Jeff

    1995-01-01

    Global Positioning System (GPS) measurements spanning approximately 3 years have been used to determine velocities for 7 sites on the Australian, Pacific and Antarctic plates. The site velocities agree with both plate model predictions and other space geodetic techniques. We find no evidence for internal deformation of the interior of the Australian plate. Wellington, New Zealand, located in the Australian-Pacific plate boundary zone, moves 20 +/- 5 mm/yr west-southwest relative to the Australian plate. Its velocity lies midway between the predicted velocities of the two plates. Relative Euler vectors for the Australia-Antarctica and Pacific-Antarctica plates agree within one standard deviation with the NUVEL-1A predictions.

  1. Break-up spots: Could the Pacific open as a consequence of plate kinematics?

    E-print Network

    Clouard, Valerie

    to hotspots. How- ever, hotspot volcanism does not fit well into the plate tectonic theory associated of plate tectonics theory, related some hotspots to spreading ridges. Morgan (1971) argued that spreadingBreak-up spots: Could the Pacific open as a consequence of plate kinematics? Valérie Clouard a

  2. How does the Pacific Plate die, and what dies with it?

    NASA Astrophysics Data System (ADS)

    Gill, J.

    2002-12-01

    Investigation continues into the demise of the Pacific Plate by the subduction, which has been its principal driving force for about 50 m.y.. Key unanswered questions in the inquiry include the following. What was the motive for subduction to start? Where is the geochemical boundary between the Pacific and Indian Plates, and what is the reason for that difference in the first place? Why do marginal basins initiate above the subducting Pacific Plate, spread for 5-10 m.y., and then stop? How much and which parts of the Pacific Plate survive to an afterlife in the continents versus descent to Hades? Most of these questions reduce to: Why are the two largest islands in the Pacific Ocean (Hawaii and Viti Levu, Fiji) so different?

  3. Three-dimensional interface cracks of elastic plates

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshio

    Fracture characterizing parameters of various three-dimensional bimaterial plates containing interface cracks arc investigated. Unlike a homogeneous plate, the asymptotic field of an interface crack is always mixed mode containing all three modes of fracture. The relative magnitude of each mode depends on the remote loading condition as well as on the extent of the mismatch between the two material properties. For most bimaterial plates under remote symmetrical loading condition, Mode 1 remains the dominant mode. Detailed computational results have shown that in single-edge-crack specimens, Modes II and III contributions arise from the modulus mismatch along the interface boundary, and their magnitudes increase with the crack length and the ratio of bending to tension. The energy release rate along the middle part of the crack front is in good agreement with the corresponding plane strain solution although greater differences are observed in individual stress-intensity factors. Near the free-surface, a significant amount of antiplane (Mode III) deformation exists. This phenomenon may play a critical role in defining fracture behavior as well as determining interface fracture toughness of bimaterial solids.

  4. Quantifying the forces needed for the rapid change of Pacific plate motion at 6 Ma

    NASA Astrophysics Data System (ADS)

    Austermann, Jacqueline; Ben-Avraham, Zvi; Bird, Peter; Heidbach, Oliver; Schubert, Gerald; Stock, Joann M.

    2011-07-01

    Studies have documented several rapid changes along the Pacific-North American, Pacific-Antarctic and Pacific-Australian plate boundaries in latest Miocene to earliest Pliocene time consistent with a sudden clockwise rotation of Pacific plate velocity relative to hotspots during this period. We test the hypothesis that this change in plate motion was initiated by cessation of subduction along the northern Melanesian arc due to the collision between the arc and the Ontong Java plateau. This hypothesis has long been formulated but never tested quantitatively. We use a geomechanical model of the lithosphere to determine the changes in plate boundary forces that are necessary to obtain the observed change in the Pacific plate motion. Our model results show that the change in motion can be explained by a clockwise rotation of the slab-related (basal-strength) component of plate driving force. The change of slab-related force from a post-6 Ma to a pre-6 Ma setting is perpendicular to the arc and points towards the Australian plate. The force per unit length is in the range of currently accepted values for subduction zones. Since there have been no other relevant changes at subduction zones along the Pacific plate boundary during the latest Miocene, we relate this change in slab-related force to the former southward-dipping Pacific plate slab along the northern Melanesian arc system which is now detached. Our model results suggest that rapid changes in plate motion can be triggered by slab detachment, with consequences for plate boundary processes even at great distances from the event.

  5. Constraining Late Cretaceous to mid Eocene plate boundaries in the southwest Pacific

    NASA Astrophysics Data System (ADS)

    Matthews, K. J.; Williams, S.; Whittaker, J. M.; Müller, D.; Clarke, G. L.; Seton, M.; Flament, N. E.

    2013-12-01

    The southwest Pacific has undergone a complex tectonic history since the Late Cretaceous, involving multiple episodes of subduction, back-arc spreading and continental deformation. Starkly contrasting reconstructions have been proposed for this period, ranging from tectonic quiescence with no plate boundary between the Lord Howe Rise (LHR) and Pacific, to widespread subduction and back-arc spreading, and this disparity reflects sparse and ambiguous data. Placing further constraints on these reconstructions is crucial for a variety of applications, from global-scale geodynamic studies using plate circuits to basin-scale studies of paleogeographic evolution and vertical motions. Geologic and kinematic data from the southwest Pacific are reviewed to better constrain the tectonic history of the region from the Late Cretaceous to mid Eocene, including the timing and location of plate boundary activity. This facilitates better constraints on the time-dependent evolution of the southwest Pacific plate circuit so that motion between plate pairs is consistent with geologic data and known tectonic regimes. The southwest Pacific comprised three spreading ridges during this time: in the Southeast Indian Ocean, Tasman Sea and Amundsen Sea. However, at least one, and possibly two other plate boundaries also accommodated relative motions: in the West Antarctic Rift System (WARS) and between the LHR and Pacific. Uncertainties in the timing and nature of plate boundaries prevent the construction of a robust reconstruction model and the implementation of a southwest Pacific plate circuit. Some previous plate models include continuous subduction east of the LHR throughout the Late Cretaceous-Cenozoic, while an alternative scenario involves the absence of plate boundaries between the LHR and Pacific until 45 Ma. Geologic observations suggests that subduction initiated to the east of New Caledonia at c. 55 Ma, including dyke emplacement and metamorphism in New Caledonia, and arc-type rocks dredged from the Tonga forearc. These geologic and kinematic data do not require a plate boundary between the LHR and Pacific from c. 84-55 Ma, in agreement with previous studies. A plate boundary may have existed before 55 Ma, however net convergence/divergence at this boundary would have been minor, with a possible strike-slip component. By combining geologic observations with a kinematic analysis, we propose that from 0-55 Ma an Antarctic plate circuit must be used in reconstructions, in which LHR-Pacific motion is unconstrained. From 55-74 Ma Antarctic or Australian circuits can be reconciled with regional geology when revised relative motion histories at the Australian-Antarctic ridge and in the WARS are adopted. A well-constrained Antarctic circuit predicts <50 km of strike-slip motion at a LHR-Pacific boundary. Alternatively, an Australian circuit assuming the LHR was part of the Pacific plate, predicts 100-150 km of extension in the WARS, that is orthogonal in the Ross Sea and oblique further east. Prior to 74 Ma neither plate circuit is preferable, as more data are needed to better constrain regional spreading histories.

  6. Rheology of the plate interface - the rock record

    NASA Astrophysics Data System (ADS)

    Wassmann, S.; Stöckhert, B.

    2012-04-01

    Models of subduction zones generally assume deformation to be localized into a comparatively narrow interplate shear zone. The cool crust of the subducted lithosphere, from which heat is additionally withdrawn by endothermic dehydration reactions, implies a cool geotherm for this region of interplate deformation. For localization of viscous flow in a region of low temperatures, specific material properties, environmental conditions, and mechanisms of deformation are prerequisite. As details on material behaviour cannot be predicted from models based on geophysical observations, the record of high pressure - low temperature (HP-LT) metamorphic rocks, probably being exhumed in a subduction channel, represents the only source of information on activated deformation mechanisms and typical stresses along the plate interface at depth. The record of blueschist facies metabasalts from the Franciscan Complex (California), of eclogite facies serpentinites from the Western Alps (Italy), and of eclogite facies micaschist from the Eastern Alps (Austria) invariably indicates that crystal plastic deformation of all minerals is subordinate. Instead, viscous flow at HP-LT metamorphic conditions is primarily by dissolution precipitation creep (DPC). Interphase boundaries act as preferred sites of dissolution. Prominent local sinks include strain shadows, dilatant fractures, and veins. Incongruent DPC is coupled with mineral reactions. DPC still predominates during the earlier stages of exhumation. Taking such observations to be representative for subducted material deformed at low temperatures along the plate interface between about 30 and 80 km depth, and exhumed without significant overprint within a weak subduction channel, the following is concluded: (1) Crystal plastic deformation and dislocation creep play no major role in long term viscous flow. (2) The absence of crystal plastic deformation all along the burial and exhumation path poses an upper bound to long term stress at the plate interface. (3) Long term deformation is essentially by dissolution precipitation creep at very low stress. (4) An aqueous fluid phase is present throughout. (5) Low stress implies little shear heating, hence supports a cool geotherm. (6) Inhomogeneous deformation to very high finite strain, controlled by contrasting rock properties, can lead to block-in-matrix structures and formation of a tectonic mélange, which may be a characteristic result of interplate deformation in the field of DPC. (7) Combined with the high strain rates expected for localized deformation between the plates, a very low viscosity of material in the interplate shear zone at depths between about 30 and 80 km is predicted.

  7. Late Cretaceous to mid Eocene plate boundaries in the southwest Pacific

    NASA Astrophysics Data System (ADS)

    Matthews, Kara J.; Dietmar Müller, R.; Whittaker, Joanne; Flament, Nicolas; Seton, Maria

    2013-04-01

    The late Cretaceous to mid Eocene history of the southwest and southernmost Pacific has been subject to starkly contrasting interpretations, ranging from relative tectonic quiescence with the Lord Howe Rise (LHR) being part of the Pacific plate to a dynamic subduction setting. In the first scenario the Tasman Sea would have formed as a consequence of divergence between the Pacific and Australian plates, whereas in the second scenario it would have formed as a marginal basin associated with subduction. The first scenario is supported by a number of arguments, including a lack of evidence for deformation and tectonic activity in New Zealand during this period and a geodynamic modelling inference, namely that the bend in the Hawaiian-Emperor chain can be better reproduced if the LHR is part of the Pacific plate. The second scenario is supported by regional plate kinematic models reconciling a variety of observations including back-arc basin formation and destruction through time and the history of arc-continent collisions. The primary problem with the first scenario is the use of a plate circuit that leaves relative motion between East and West Antarctica unconstrained, leading to an improbable history of periodic compression and extension. The main problem with the alternative scenario is a lack of sampled late Cretaceous volcanic arc rocks east of the LHR. We analysed available geological and geophysical data to constrain the locations of and movements along the plate boundaries in the southwest and southern Pacific from the late Cretaceous to mid Eocene, and assessed how Pacific plate motion is best quantified during this period. Geological and geophysical evidence suggests that a plate boundary separated the Pacific plate from the LHR. The distribution of lower mantle slab material that is imaged by seismic tomography beneath New Zealand is best explained if subduction occurred to the east of the LHR during the entire late Cretaceous to mid Eocene period. Rocks from ophiolitic nappes in the North Island of New Zealand, New Caledonia and Papua New Guinea show evidence of having formed in a back-arc basin during this period, consistent with a subduction zone near the LHR. Although New Zealand is commonly viewed as tectonically quiescent at this time, deformation at several locations to the east and west of the present-day Alpine Fault suggests that a plate boundary cut through Zealandia during Tasman Sea opening. As the LHR was not attached to the Pacific plate and subduction occurred to the east and north of the LHR we suggest that Pacific plate motion is best quantified using a plate circuit through East and West Antarctica, avoiding this zone of southwest Pacific subduction. Future work should focus on better constraining the location of and motion along the late Cretaceous-mid Eocene plate boundary through New Zealand to enable the use of a plate circuit via Australia.

  8. Tectonic implications of post-30 Ma Pacific and North American relative plate motions

    USGS Publications Warehouse

    Bohannon, R.G.; Parsons, T.

    1995-01-01

    The Pacific plate moved northwest relative to North America since 42 Ma. The rapid half rate of Pacific-Farallon spreading allowed the ridge to approach the continent at about 29 Ma. Extinct spreading ridges that occur offshore along 65% of the margin document that fragments of the subducted Farallon slab became captured by the Pacific plate and assumed its motion proper to the actual subduction of the spreading ridge. This plate-capture process can be used to explain much of the post-29 Ma Cordilleran North America extension, strike slip, and the inland jump of oceanic spreading in the Gulf of California. Much of the post-29 Ma continental tectonism is the result of the strong traction imposed on the deep part of the continental crust by the gently inclined slab of subducted oceanic lithosphere as it moved to the northwest relative to the overlying continent. -from Authors

  9. Geophysics of the Pitman Fracture Zone and Pacific-Antarctic Plate Motions During the Cenozoic

    NASA Astrophysics Data System (ADS)

    Cande, Steven C.; Raymond, Carol A.; Stock, Joann; Haxby, William F.

    1995-11-01

    Multibeam bathymetry and magnetometer data from the Pitman fracture zone (FZ) permit construction of a plate motion history for the South Pacific over the past 65 million years. Reconstructions show that motion between the Antarctic and Bellingshausen plates was smaller than previously hypothesized and ended earlier, at chron C27 (61 million years ago). The fixed hot-spot hypothesis and published paleomagnetic data require additional motion elsewhere during the early Tertiary, either between East Antarctica and West Antarctica or between the North and South Pacific. A plate reorganization at chron C27 initiated the Pitman FZ and may have been responsible for the other right-stepping fracture zones along the ridge. An abrupt (8^circ) clockwise rotation in the abyssal hill fabric along the Pitman flowline near the young end of chron C3a (5.9 million years ago) dates the major change in Pacific-Antarctic relative motion in the late Neogene.

  10. Interaction of Pacific and Philippine Sea Plates From Vp, Vs Tomography Under Kanto, Japan

    NASA Astrophysics Data System (ADS)

    Wu, F. T.; Okaya, D.; Sato, H.; Hirata, N.

    2005-12-01

    The subduction of the Philippine Sea plate over the Pacific plate under the Kanto Plain is an unique plate tectonic system in the world. The recent densification of the seismic network in Kanto and the wide use of deep (~3 km) borehole and ocean bottom seismic sensors have created a high quality arrival times dataset from local shallow and intermediate earthquakes. Relatively high resolution (5km horizontal and 2 km vertical) seismic velocity tomography and relocated seismicity have been derived from these data. More details can therefore be seen than earlier, similarly comprehensive studies of Kanto (e.g., Ishida, 1992). The area of study is demarcated by latitudes 34ON and 38ON and longitudes 137OE and 141OE. Benz's tomography code (Benz et al.,1996 ) is employed. Within this area, while the geometry of the Pacific subduction zone appears clearly both in terms of velocity anomalies and associated double-layered seismicity, that of the Philippine Sea plate is quite complex. A few hundred kilometers to the west of Izu Peninsula, the subducting plate is marked by well defined gently dipping seismic and higher velocity zones. Within a few hundred kilometers to the west of Izu Peninsula however there is no clear Wadata-Benioff zone nor high velocity anomalies to help define PSP. Yet on the east side a well defined WBZ with an anomalous seismic zone can readily be seen and it nearly bottomed on top of the Pacific subduction zone. Well-defined WBZ continues eastward but as the Pacific zone gets shallower the segment of PSP subduction zone gets shorter as they all bottom against the Pacific plate. and that the number of segments of PSP increase as the tip of the Pacific mantle wedge is approached. The Vp and Vs ratios, in combination with the Vp allows us to explore the possible petrology (Christensen, 1996) associated with the tectonic processes in the area.

  11. Pacific-Antarctic-Australia motion and the formation of the Macquarie Plate

    NASA Astrophysics Data System (ADS)

    Cande, Steven C.; Stock, Joann M.

    2004-04-01

    Magnetic anomaly and fracture zone data on the Southeast Indian Ridge (SEIR) are analysed in order to constrain the kinematic history of the Macquarie Plate, the region of the Australian Plate roughly east of 145°E and south of 52°S. Finite rotations for Australia-Antarctic motion are determined for nine chrons (2Ay, 3Ay, 5o, 6o, 8o, 10o, 12o, 13o and 17o) using data limited to the region between 88°E and 139°E. These rotations are used to generate synthetic flowlines which are compared with the observed trends of the easternmost fracture zones on the SEIR. An analysis of the synthetic flowlines shows that the Macquarie Plate region has behaved as an independent rigid plate for roughly the last 6 Myr. Finite rotations for Macquarie-Antarctic motion are determined for chrons 2Ay and 3Ay. These rotations are summed with Australia-Antarctic rotations to determine Macquarie-Australia rotations. We find that the best-fit Macquarie-Australia rotation poles lie within the zone of diffuse intraplate seismicity in the South Tasman Sea separating the Macquarie Plate from the main part of the Australian Plate. Motion of the Macquarie Plate relative to the Pacific Plate for chrons 2Ay and 3Ay is determined by summing Macquarie-Antarctic and Antarctic-Pacific rotations. The Pacific-Macquarie rotations predict a smaller rate of convergence perpendicular to the Hjort Trench than the Pacific-Australia rotations. The onset of the deformation of the South Tasman Sea and the development of the Macquarie Plate appears to have been triggered by the subduction of young, buoyant oceanic crust near the Hjort Trench and coincided with a clockwise change in Pacific-Australia motion around 6 Ma. The revised Pacific-Australia rotations also have implications for the tectonics of the Alpine Fault Zone of New Zealand. We find that changes in relative displacement along the Alpine Fault have been small over the last 20 Myr. The average rate of convergence over the last 6 Myr is about 40 per cent smaller than in previous models.

  12. Bathymetry of the Pacific plate and its implications for thermal evolution of lithosphere and mantle dynamics

    E-print Network

    Shapiro, Nikolai

    for the Pacific plate, and we removed the effects of sediments, seamounts, and large igneous provinces (LIPs), using recently available data sets of high-resolution bathymetry, sediments, seamounts, and LIPs. We found that the removal of seamounts and LIPs results in nearly uniform standard deviations in ocean

  13. Finite element computation of the vibrations of a plate-fluid system with interface damping

    E-print Network

    Rodríguez, Rodolfo

    Finite element computation of the vibrations of a plate-fluid system with interface damping Alfredo the thickness of the plate becomes small. Finally the computed resonance frequencies are compared with those excitation. The system consists of an acoustic fluid and a plate, with a thin layer of a noise damping

  14. The cretaceous dynamics of the pacific plate and stages of magmatic activity in Northeastern Asia

    NASA Astrophysics Data System (ADS)

    Stepashko, A. A.

    2006-05-01

    The dynamics of the Pacific Plate is recorded in the systematic variation of location and the 40Ar-39Ar age of seamounts in the western Pacific from 120 to 65 Ma ago. The seamounts are grouped into three linear zones as long as 5000 km. The seamounts become younger in the southeastern direction along the strike of these zones. Correlation between age and location of seamounts allows division of the history of their formation into three stages. The rate of seamount growth was relatively low (2-4 cm/yr) during the first and the third stages within the intervals of 120-90 and 85-65 Ma, whereas during the second stage (90-85 Ma), the seamounts were growing very fast (80-100 cm/yr). In the midst of this stage, at ˜87 Ma ago, the magmatic activity increased abruptly. The dynamics of seamount building is in good agreement with (1) pulses in the development of the Ontong Java, Manihiki, and Caribbean-Colombian oceanic plateaus; (2) the age of spreading acceleration in the mid-Cretaceous; and (3) the short period when the Izanagi Plate ceased to exist and the Kula Plate was formed. The variation of the seamounts’ age and location is in consistence with the hypothesis of diffuse extension of the Pacific Plate in the course of its motion with formation of impaired zones of decompression melting. The direction of extension (325°-340° NW) calculated from the strike of seamount zones is consistent with the path of the Pacific Plate (330° NW) in the Late Cretaceous. The immense perioceanic volcanic belts were formed at that time along the margin of the Asian continent. The Okhotsk-Chukchi Peninsula Belt extends at a right angle to the compression vector. Three stages of this belt’s evolution are synchronous with the stages of seamount formation in the Pacific Plate. The delay in the origination of the East Sikhote-Alin Volcanic Belt and its different orientation were caused by counterclockwise rotation of the vector of convergence of oceanic and continental plates in the mid-Cretaceous. At the same time, i.e., 95-85 Ma ago, the volcanic activity embraced the entire continental margin and the tin granites were emplaced everywhere in eastern Asia. This short episode (90 ± 5 Ma) corresponds to the mid-Cretaceous maximum of compression of the continental margin, and its age fits a culmination in extension of the Pacific Plate well.

  15. Overview on the Plate Boundaries Along the Western Mexican Pacific Margin

    NASA Astrophysics Data System (ADS)

    Mortera-Gutierrez, C. A.; Bandy, W. L.; Michaud, F.; Ortega Ramírez, J.

    2013-05-01

    The cinematic of the Pacific, Rivera and Cocos oceanic plates have a significant impact on the subduction process and seismic cycles occurring along the western Mexican Pacific margin of the North American and Caribbean plates. Sections of Pacific (PAC), Rivera (RIV), Cocos (COC), North American (NAM) and Caribbean (CAB) plate boundaries along the western margin of Mexico are not well constrained. From north to south: the transform-rift system at Gulf of California has been generally considered as part of PAC-NAM plate boundary. However results of the FAMEX cruise at 2002 evidenced that Tosco-Abreojos Fault System along the western margin of Baja California Peninsula is active. Should this tectonic structure be considered as a plate boundary? At the RIV plate northern corner (including Mazatlan Basin), the scatter seismicity recorded between Tamayo FZ and the Marias Islands restricts the characterization of the plate boundary between the RIV and NAM plates. Some authors have proposed that Tamayo FZ and Marias I. Escarpment are the RIV-NAM plate boundary. Recently other authors have called that RIV-NAM boundary is a geomorphology lineament that runs from a Rivera Rise transform at 23N to the northern end of Marias I. Escarpment. Even so this concept is not sustained with seismic activity. Further this thought would imply that the oceanic lithosphere of Mazatlan Basin would form part of NAM plate. Other thoughts are either that there is a diffuse RIV-NAM plate boundary to the north of the Maria Archipelago, or Middle America Subduction Zone is gradually extending northward of the Maria Is. While the plate boundary at SE corner of the RIV plate is neither well defined morphologically nor seismically constraint, offshore Colima Coast. Some authors have proposed that this zone is a diffuse plate boundary between RIV and COC plates, result of a NE-SW shear plate motion. Other authors have proposed that the RIV-COC boundary extends E-W from the El Gordo Graben (EGG) at the Middle American Trench (MAT) to northern tip of the East Pacific Rise (EPR). Results of recently multibeam and magnetic surveys indicate that this boundary is possible segmented as an echelon E-W structure, north of EGG. Clearly these hypotheses on the RIV-COC plate boundary show that its configuration is neither well seismic nor morphology constrained. To the south, the triple junction point of COC, NAM, and CAB plate boundaries is also another case where the boundaries are poorly constrained seismically and morphologically. Traditionally, the COC-NAM-CAB triple junction point has been positioned where the MAT trend bends by the Tehuantepec Ridge (TR) collision, but no offshore geophysical data sustain that NAM-CAB plate boundary extends to MAT-TR point. In the last decade, the Servicio Sismológico Nacional (SSN) has extended its seismic station network at the southern Mexican territory. From this data, the distribution of offshore earthquakes covers a broad marine zone in front the Chiapas and Guatemala coastline and does not show a defined earthquake concentration associated to the proposed offshore extension of the Polochic-Motogua Fault through Guatemala and Mapastepec Fault through Chiapas, Mexico.

  16. Incoming plate faulting in the Northern and Western Pacific and implications for subduction zone water budgets

    NASA Astrophysics Data System (ADS)

    Emry, Erica L.; Wiens, Douglas A.

    2015-03-01

    The greatest uncertainty in the amount of water input into the Earth at subduction zones results from poor constraints on the degree of mantle serpentinization in the incoming plate. Recent studies suggest that the depth of serpentinization within the incoming plate mantle is likely controlled by the depth of extensional faulting caused by lithospheric bending at the outer rise and trench. We explore the maximum depth of extension within the incoming plate at Northwestern Pacific subduction zones in order to estimate the depth limit of serpentinization and to identify any significant variation between subduction zone segments. We relocate trench earthquakes to identify which events occurred within the incoming plate and determine accurate depths for 63 incoming plate earthquakes occurring during 1988-2011 by inverting teleseismic broadband P and SH waveforms. We observe that the top 10-15 km of the incoming plate mantle experiences extensional faulting at all of the subduction zones with a reasonable sample of earthquakes; 60% of the total number of extensional earthquakes occur at crustal depths or within the top 5 km of the incoming plate mantle, 80% occur above 10 km within the mantle, and 95% occur above 15 km. There is evidence for variation throughout the different regions of study, for example extensional earthquakes occur down to 20 km below the crust in the western Aleutians and Izu-Bonin. We propose that the incoming plate mantle is most strongly hydrated in the upper 5 km, and that partial serpentinization exists regionally within the incoming plate mantle to ?15 km. Making reasonable assumptions about the degree of serpentinization and incorporating previous estimates of crustal water, we calculate that the total water carried into the Northern and Western Pacific subduction zones is generally higher than previous estimates, and is approximately 4- 6 ×108 Tg /Myr, or ? 45- 70 ×103 Tg /Myr per kilometer of subduction zone.

  17. Comparison of interface contact profiles of a new minimum contact locking compression plate and the limited contact dynamic compression plate

    PubMed Central

    Xiong, Yan; Zhao, Yu Feng; Xing, Shu Xing; Du, Quan Yin; Sun, Hong Zhen; Wang, Zi Ming; Wu, Si Yu

    2009-01-01

    In this study, we investigated whether or not a new minimum contact locking compression plate (MC-LCP) can provide advantages over the limited contact dynamic compression plate (LC-DCP) in the context of interface contact area and force. Six matched pairs of cadaveric bones were used for each of three bone types of the humerus, radius and ulna. For each bone type, one of two bone plates was fixed to either of two matched cadaveric bones at the middle of the diaphysis. The interface contact area and force of the plate fixed to three types of human cadaveric bones were evaluated using Fuji prescale pressure sensitive film. Data were quantitated using computer-assisted image analysis. Results showed that the average force between the MC-LCP and humerus or radius was about half of that of the LC-DCP. And the average force between the MC-LCP and ulna was one third less than that of the LC-DCP. Meanwhile, the interface contact area between the MC-LCP and humerus or radius was also about half of that of the LC-DCP, and the interface contact area between the MC-LCP and ulna was less than one third of that of the LC-DCP. These results indicate that the MC-LCP has lower interface contact area and lower average force than that of the LC-DCP. Thus, the MC-LCP system may be a good alternate to treat forearm diaphyseal fractures. PMID:19603166

  18. Constraints on Pacific plate kinematics and dynamics with global positioning system measurements

    NASA Technical Reports Server (NTRS)

    Dixon, T. H.; Golombek, M. P.; Thornton, C. L.

    1985-01-01

    A measurement program designed to investigate kinematic and dynamic aspects of plate tectonics in the Pacific region by means of satellite observations is proposed. Accuracy studies are summarized showing that for short baselines (less than 100 km), the measuring accuracy of global positioning system (GPS) receivers can be in the centimeter range. For longer baselines, uncertainty in the orbital ephemerides of the GPS satellites could be a major source of error. Simultaneous observations at widely (about 300 km) separated fiducial stations over the Pacific region, should permit an accuracy in the centimeter range for baselines of up to several thousand kilometers. The optimum performance level is based on the assumption of that fiducial baselines are known a priori to the centimeter range. An example fiducial network for a GPS study of the South Pacific region is described.

  19. Petrologic Aspects of Seamount and Guyot Volcanism on the Ancestral Mesozoic Pacific Plate: a Review

    NASA Astrophysics Data System (ADS)

    Natland, J. H.

    2007-12-01

    Hundreds of large seamounts and guyots are widely scattered almost in a "shotgun-blast" arrangement in an area about the size of the United States west of the Mississippi River on the Mesozoic Pacific plate between the Mariana Trench and the Gilbert Islands. Most of these formed between ~160-100 Ma while the Pacific plate was surrounded by spreading ridges and growing outward in all directions. There is little to no indication that the seamounts and guyots formed along linear seamount chains; existing radiometric-age data show no age progressions. The volcanoes appear to have formed in response to a uniform stress configuration across the plate, which was either not moving or moving very slowly at the time (1, 2), much like the modern Antarctic plate. When the growing plate started to encounter subduction systems in the western Pacific at ~90 Ma, consistent stress patterns began to develop, and the broad linear Gilbert and Line volcanic ridge systems began to form. Even then, however, considerable overlapping of volcanism occurred, and only the most general age progressions are evident in existing data. Petrologic data from samples obtained from dozens of volcanic summits by dredging and beneath several carbonate platforms by drilling reveal considerable diversity in development of differentiated alkalic magmatic lineages rooted in diverse parental basaltic rocks. These include transitional, alkalic and basanitic compositions, with differentiates of hawaiite, mugearite, trachyte and one phonolite. Many of the basaltic rocks are partly to significantly transformed by alteration under oxidative conditions (dredged rocks) and both oxidative and non-oxidative conditions (drilled rocks). This can make estimations of mantle geochemical provenance difficult. Nevertheless, the province has been linked by backtracking techniques to the modern SOPITA region of the South Pacific (3), and its rocks show enrichments in trace elements and isotopic characteristics similar to lavas from the Cook-Austral, Marquesas, Society, and Samoan linear volcanic chains. Significantly, Hawaiian- type tholeiite has not been sampled in the region, and the diversity of basaltic rocks and differentiates has always been high. Even unusual potassic nephelinites (K2O > Na2O) with phenocrysts of kaersutitic amphibole or phlogopite occur in the Wake and Line Seamounts. These resemble lavas of portions of the East African Rift, but also have counterparts in the Samoan and Society chains, and resemble very young basalts obtained on the outer trench swell of the Pacific plate near Japan. I suggest that variably and often strongly enriched material was originally supplied to the shallow upper mantle beneath a broad region of the Pacific plate during the Mesozoic; that partial melts of this material were subsequently tapped along major fracture systems that developed to form linear island chains as stress configurations changed on the Pacific plate; and that narrow plume conduits of ascending mantle have never figured in the emplacement of the broadly distributed enriched SOPITA volcanoes. 1) Natland, J. H., and Winterer, E.L., 2005, GSA Spec. Paper 388: 687-710. 2) Larson, R.L., et al., 1992, Proc. ODP, Sci Results, 129: p. 615-631; 3) Staudigel, H., et al., 1991, EPSL, 102: 24-44.

  20. Role of Transtension in Rifting at the Pacific-North America Plate Boundary

    NASA Astrophysics Data System (ADS)

    Stock, J. M.

    2011-12-01

    Transtensional plate motion can be accommodated either in a localized zone of transtensional rifting or over a broader region. Broader zones of deformation can be classified either as diffuse deformation or strain partitioning (one or more major strike-slip shear zones geographically offset from a region of a extensional faulting). The Pacific-North America plate boundary in southwestern North America was transtensional during much of its history and has exhibited the full range of these behaviors at different spatial scales and in different locations, as recorded by fault motions and paleomagnetic rotations. Here we focus on the northern Gulf of California part of the plate boundary (Upper and Lower Delfin basin segments), which has been in a zone of transtensional Pacific-North America plate boundary motion ever since the middle Miocene demise of adjacent Farallon-derived microplates. Prior to the middle Miocene, during the time of microplate activity, this sector of North America experienced basin-and-range normal faults (core complexes) in Sonora. However there is no evidence of continued extensional faulting nor of a Gulf-related topographic depression until after ca 12 Ma when a major ignimbrite (Tuff of San Felipe/ Ignimbrite of Hermosillo) was deposited across the entire region of the future Gulf of California rift in this sector. After 12 Ma, faults disrupted this marker bed in eastern Baja California and western Sonora, and some major NNW-striking right-lateral faults are inferred to have developed near the Sonoran coast causing offset of some of the volcanic facies. However, there are major tectonic rotations of the volcanic rocks in NE Baja California between 12 and 6 Ma, suggesting that the plate boundary motion was still occurring over a broad region. By contrast, after about 6 Ma, diminished rotations in latest Miocene and Pliocene volcanic rocks, as well as fault slip histories, show that plate boundary deformation became localized to a narrower transtensional zone of long offset strike-slip faults and intervening basins (the modern Gulf of California basin and transform fault system). Within and adjacent to this zone the fault patterns continued to evolve, with new plate boundary strike-slip faults breaking into previously intact blocks of continent. These new strike-slip faults were not accompanied by any widespread zones of tectonic rotation. This suggests that if widespread rotations are occurring, plate boundary transtension has not yet localized and the strike-slip faults are not yet accommodating most of the plate boundary slip. The cessation of widespread and significant vertical axis rotations could indicate strain localization and the increasing importance of throughgoing strike-slip faults (a precursor to fully oceanic rifting) along a transtensional plate boundary.

  1. The 2011 Tohoku-oki Earthquake related to a large velocity gradient within the Pacific plate

    NASA Astrophysics Data System (ADS)

    Matsubara, Makoto; Obara, Kazushige

    2015-04-01

    We conduct seismic tomography using arrival time data picked by the high sensitivity seismograph network (Hi-net) operated by National Research Institute for Earth Science and Disaster Prevention (NIED). We used earthquakes off the coast outside the seismic network around the source region of the 2011 Tohoku-oki Earthquake with the centroid depth estimated from moment tensor inversion by NIED F-net (broadband seismograph network) as well as earthquakes within the seismic network determined by Hi-net. The target region, 20-48N and 120-148E, covers the Japanese Islands from Hokkaido to Okinawa. A total of manually picked 4,622,346 P-wave and 3,062,846 S-wave arrival times for 100,733 earthquakes recorded at 1,212 stations from October 2000 to August 2009 is available for use in the tomographic method. In the final iteration, we estimate the P-wave slowness at 458,234 nodes and the S-wave slowness at 347,037 nodes. The inversion reduces the root mean square of the P-wave traveltime residual from 0.455 s to 0.187 s and that of the S-wave data from 0.692 s to 0.228 s after eight iterations (Matsubara and Obara, 2011). Centroid depths are determined using a Green's function approach (Okada et al., 2004) such as in NIED F-net. For the events distant from the seismic network, the centroid depth is more reliable than that determined by NIED Hi-net, since there are no stations above the hypocenter. We determine the upper boundary of the Pacific plate based on the velocity structure and earthquake hypocentral distribution. The upper boundary of the low-velocity (low-V) oceanic crust corresponds to the plate boundary where thrust earthquakes are expected to occur. Where we do not observe low-V oceanic crust, we determine the upper boundary of the upper layer of the double seismic zone within high-V Pacific plate. We assume the depth at the Japan Trench as 7 km. We can investigate the velocity structure within the Pacific plate such as 10 km beneath the plate boundary since the rays from the hypocenter around the coseismic region of the Tohoku-oki earthquake take off downward and pass through the Pacific plate. The landward low-V zone with a large anomaly corresponds to the western edge of the coseismic slip zone of the 2011 Tohoku-oki earthquake. The initial break point (hypocenter) is associated with the edge of a slightly low-V and low-Vp/Vs zone corresponding to the boundary of the low- and high-V zone. The trenchward low-V and low-Vp/Vs zone extending southwestward from the hypocenter may indicate the existence of a subducted seamount. The high-V zone and low-Vp/Vs zone might have accumulated the strain and resulted in the huge coseismic slip zone of the 2011 Tohoku earthquake. The low-V and low-Vp/Vs zone is a slight fluctuation within the high-V zone and might have acted as the initial break point of the 2011 Tohoku earthquake. Reference Matsubara, M. and K. Obara (2011) The 2011 Off the Pacific Coast of Tohoku earthquake related to a strong velocity gradient with the Pacific plate, Earth Planets Space, 63, 663-667. Okada, Y., K. Kasahara, S. Hori, K. Obara, S. Sekiguchi, H. Fujiwara, and A. Yamamoto (2004) Recent progress of seismic observation networks in Japan-Hi-net, F-net, K-NET and KiK-net, Research News Earth Planets Space, 56, xv-xxviii.

  2. Ridge subduction sparked reorganization of the Pacific plate-mantle system 60-50 million years ago

    NASA Astrophysics Data System (ADS)

    Seton, Maria; Flament, Nicolas; Whittaker, Joanne; Müller, R. Dietmar; Gurnis, Michael; Bower, Dan J.

    2015-03-01

    A reorganization centered on the Pacific plate occurred ~53-47 million years ago. A "top-down" plate tectonic mechanism, complete subduction of the Izanagi plate, as opposed to a "bottom-up" mantle flow mechanism, has been proposed as the main driver. Verification based on marine geophysical observations is impossible as most ocean crust recording this event has been subducted. Using a forward modeling approach, which assimilates surface plate velocities and shallow thermal structure of slabs into mantle flow models, we show that complete Izanagi plate subduction and margin-wide slab detachment induced a major change in sub-Pacific mantle flow, from dominantly southward before 60 Ma to north-northeastward after 50 Ma. Our results agree with onshore geology, mantle tomography, and the inferred motion of the Hawaiian hot spot and are consistent with a plate tectonic process driving the rapid plate-mantle reorganization in the Pacific hemisphere between 60 and 50 Ma. This reorganization is reflected in tectonic changes in the Pacific and surrounding ocean basins.

  3. Can clay minerals account for the behavior of non-asperity on the subducting plate interface?

    NASA Astrophysics Data System (ADS)

    Katayama, Ikuo; Kubo, Tatsuro; Sakuma, Hiroshi; Kawai, Kenji

    2015-12-01

    Seismicity along the subducting plate interface shows regional variation, which has been explained by the seismic asperity model where large earthquakes occur at strongly coupled patches that are surrounded by weakly coupled regions. This suggests that the subduction plate interface is heterogeneous in terms of frictional properties; however, the mechanism producing the difference between strong and weak couplings remains poorly understood. Here, we propose that the heterogeneity of the fluid pathway and of the spatial distribution of clay minerals plays a key role in the formation of non-asperity at the subducting plate interface. We use laboratory measurements of frictional properties to show that clay minerals on a simulated fault interface are characterized by weak and slow recovery, whereas other materials such as quartz show relatively quick recovery and thereby strong coupling on the fault surface. Aqueous fluids change the mineralogy at the plate interface by producing clay minerals due to hydrate reactions, suggesting that the hydrated weakly coupled regions act as a non-asperity and form a barrier to rupture propagation along the plate boundary at the depths of seismogenic zone.

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

    NASA Astrophysics Data System (ADS)

    Osada, Kinue; Yoshizawa, Kazunori; Yomogida, Kiyoshi; Suetsugu, Daisuke; Bina, Craig; Inoue, Toru; Wiens, Douglas; Jellinek, Mark

    2010-11-01

    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 ScSp signals in the original records. At first, we set up five blocks for the region in plate dip directions. After aligning the travel times of ScS and stacking seismograms among stations in a given sub-block perpendicular to each dip direction, we searched for the optimal plate model (i.e., two-dimensional geometry of the upper boundary) for each block. The model was parameterized by seven depth grids, and seismograms were stacked based on the travel time of ScSp as a time lag of each sub-block, so that the optimal model would yield the maximum spectral energy of ScSp after stacking. This model parameter search was conducted, using ray tracings of ScSp with a reference velocity model and a non-linear inversion scheme (Neighbourhood Algorithm). The optimal model of each block was combined each other by cubic spline interpolation, in order to construct an overall three-dimensional geometry of the upper boundary of the plate. Next, we performed the frequency-wavenumber ( f- k) spectral analysis to refine the above result. Assuming each station as a reference point, we made beam output from records of its adjacent stations as a function of wavenumber vector ( kx, ky) and frequency. The peak of its power spectrum was considered to represent the wavenumber vector of ScSp, that is, azimuth of arrival and slowness, so that we can estimate the position and depth of the corresponding ScS- ScSp conversion. In the frequency range from 0.5 to 1.5 Hz, we could estimate the conversion points for 21 stations or hypothetical arrays, and revised the geometry of the upper boundary obtained by the non-linear stacking approach in the previous step. The final plate model was compared with the distribution of intraplate earthquakes in the Pacific plate. This comparison clearly reveals that the upper seismic zone merges with the lower from 150 to 200 km in depth, deviating systematically away from the upper boundary where the boundary is slightly bumped in a convex manner.

  5. Seismic velocity structure of the subducting Pacific plate in the Izu-Bonin region

    SciTech Connect

    Iidaka, Takashi; Mizoue, Megumi; Suyehiro, Kiyoshi )

    1992-10-01

    Observed travel time residual data from a spatially dense seismic network above deep earthquakes in the Izu-Bonin region are compared with 3D ray tracing calculations. The data are inconsistent with a homogeneous slab model and consistent with a heterogenous slab model with regional velocity variations. The residual data can be explained by a model that has a velocity gradient within the slab. In the subducting Pacific plate, the velocity near the center of the slab is faster than that near the upper boundary, and gradually decreases toward the bottom of the plate. A model with a velocity decrease of 3 percent, as predicted by a thermal profile, explains the observed data. 52 refs.

  6. Thermal study of interface between the Orbiter cold plate and typical Shuttle spacecraft payload flight electronics

    NASA Technical Reports Server (NTRS)

    Hwangbo, H.; Coyle, M. J.

    1979-01-01

    Spacelab provides a set of Freon line plumbing and cold plates for experiment equipments which are located in the Shuttle pallet and which need active thermal control. The reported study deals with the thermal problem of attaching a Command and Data Handling module with various electronic boxes whose combined footprints on the baseplate are much larger than the cold plate. A description of two modules and the cold plate assembly in the pallet is presented and a thermal model description is provided. The method employed in modeling heat pipes-honey-comb matrix is based upon an effective conductance between the heat pipe vapor and the walls of the heat pipe. The considered thermal models and a computer program are used to perform steady-state thermal analyses. The temperature gradients in the large module baseplate attached to the small cold plate are predicted as a function of the interface plate thickness.

  7. On gravity from SST, geoid from Seasat, and plate age and fracture zones in the Pacific

    NASA Technical Reports Server (NTRS)

    Marsh, B. D.; Marsh, J. G.; Williamson, R. G. (principal investigators)

    1984-01-01

    A composite map produced by combining 90 passes of SST data show good agreement with conventional GEM models. The SEASAT altimeter data were deduced and found to agree with both the SST and GEM fields. The maps are dominated (especially in the east) by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Comparison with regional bathymetric data shows a remarkedly close correlation with plate age. Most anomalies in the east half of the Pacific could be partly caused by regional differences in plate age. The amplitude of these geoid or gravity anomalies caused by age differences should decrease with absolute plate age, and large anomalies (approximately 3 m) over old, smooth sea floor may indicate a further deeper source within or perhaps below the lithosphere. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantle without complete thermal equilibration was considered. A plume emanating from a buoyant layer 100 km thick and 10,000 times less viscous than the surrounding mantle should have a diameter of about 400 km and must ascend at about 10 cm/yr to arrive still anomalously hot in the uppermost mantle.

  8. Active Pacific North America Plate boundary tectonics as evidenced by seismicity in the oceanic lithosphere offshore Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Hauksson, Egill; Kanamori, Hiroo; Stock, Joann; Cormier, Marie-Helene; Legg, Mark

    2014-03-01

    Pacific Ocean crust west of southwest North America was formed by Cenozoic seafloor spreading between the large Pacific Plate and smaller microplates. The eastern limit of this seafloor, the continent-ocean boundary, is the fossil trench along which the microplates subducted and were mostly destroyed in Miocene time. The Pacific-North America Plate boundary motion today is concentrated on continental fault systems well to the east, and this region of oceanic crust is generally thought to be within the rigid Pacific Plate. Yet, the 2012 December 14 Mw 6.3 earthquake that occurred about 275 km west of Ensenada, Baja California, Mexico, is evidence for continued tectonism in this oceanic part of the Pacific Plate. The preferred main shock centroid depth of 20 km was located close to the bottom of the seismogenic thickness of the young oceanic lithosphere. The focal mechanism, derived from both teleseismic P-wave inversion and W-phase analysis of the main shock waveforms, and the 12 aftershocks of M ˜3-4 are consistent with normal faulting on northeast striking nodal planes, which align with surface mapped extensional tectonic trends such as volcanic features in the region. Previous Global Positioning System (GPS) measurements on offshore islands in the California Continental Borderland had detected some distributed Pacific and North America relative plate motion strain that could extend into the epicentral region. The release of this lithospheric strain along existing zones of weakness is a more likely cause of this seismicity than current thermal contraction of the oceanic lithosphere or volcanism. The main shock caused weak to moderate ground shaking in the coastal zones of southern California, USA, and Baja California, Mexico, but the tsunami was negligible.

  9. Mantle Flow Beneath the Juan de Fuca and East Pacific Rise Spreading Centers and Adjacent Plates

    NASA Astrophysics Data System (ADS)

    Toomey, D. R.; Hooft, E. E.; Wilcock, W. S.

    2010-12-01

    Observations of seismic anisotropy are a principal means of inferring the direction of mantle flow beneath tectonic plates. Azimuthal anisotropy of mantle head waves (Pn) observed in mid-plate settings, for example, has been used to infer that beneath oceanic crust the mantle flow that is frozen in is parallel to the paleospreading direction. While the agreement between historical measurements of azimuthal anisotropy and paleospreading direction is good, the combined uncertainties in experimental results (many of which date back 30 to 50 years) and in inferring the paleospreading direction are often 10-15°. In contrast to historical results from mid-plate settings, recent studies of Pn anisotropy beneath the East Pacific Rise (EPR) and the Mid-Atlantic Ridge reveal that the fast-direction of seismic anisotropy - and by inference the direction of mantle flow - is skewed with respect to the current spreading direction. This result indicates that sub-ridge mantle flow is not an entirely passive response to plate spreading. Here we use data from recent active-source seismic experiments to investigate azimuthal anisotropy of Pn arrivals in two near-ridge settings. These modern experiments, which use dense arrays of ocean-bottom seismometers (OBSs) and well-navigated seismic shooting lines, can constrain azimuthal anisotropy to within ±1°. One data set is from the multi-scale Endeavour seismic tomography experiment (ETOMO) that took place in September 2009. Seismic data were collected using 68 four-component OBSs at 64 sites and the 6600 in3 airgun array of the R/V Marcus G. Langseth. The study includes 5567 shots covering 90 km along-axis and 50 km across. The second data set is from the UNDERSHOOT experiment, which was conducted at the EPR between the Siqueiros and Clipperton transforms, a section of ridge that is sub-divided by the 9°03'N overlapping spreading center (OSC). Seismic data were collected using a combination of four-component OBSs and single-component hydrophones at 57 sites and the 8500 in3 airgun array of the R/V Maurice Ewing. The study includes ~5000 shots covering 200 km along-axis and 100 km across. For each data set we document evidence for mantle anisotropy using Pn arrivals that propagate beneath the axis of spreading and for paths that sample solely the Pacific, Juan de Fuca and Cocos plates. We also present results for subsets of the data that are grouped geographically. For the EPR we select data subsets that sample three regions, one each north and south of the 9°03'N OSC and one centered on the OSC. For these subsets, the azimuth of anisotropy is effectively identical to that reported previously for the entire data set (~10° anticlockwise of the spreading direction). We thus conclude that the orientation of seismic anisotropy does not vary with local plate boundary geometry, e.g. the trend of ridge segments which differ to either side of the OSC or the presence of the OSC itself. Instead, the anisotropy is a regional-scale signal related to the azimuth of mantle divergence. Our results will further test the hypothesis that beneath spreading centers the axes of mantle upwelling and asthenospheric flow are skewed with respect to the plate spreading direction.

  10. Block kinematics of the PacificNorth America plate boundary in the southwestern United States from inversion of GPS,

    E-print Network

    McCaffrey, Robert

    Block kinematics of the Pacific­­North America plate boundary in the southwestern United States, and earthquake-derived fault slip vector azimuths are inverted for block angular velocities, creep on block-bounding faults, permanent strain rates within the blocks, and the rotations of 11 published GPS velocity fields

  11. A passive and active seismic experiment near the Boso triple junction in the far northwestern part of the Pacific plate

    NASA Astrophysics Data System (ADS)

    Yamada, T.; Mochizuki, K.; Shinohara, M.; Machida, Y.; Shinbo, T.; Nakahigashi, K.; Yagi, T.; Abe, H.; Hashimoto, S.; Shoji, W.; Sato, T.; Mizuno, M.; Uehira, K.; Hino, R.; Murai, Y.; Oguma, K.

    2011-12-01

    The Pacific Plate subducts beneath northeastern Japan along the Japan Trench and beneath the Izu-Bonin-Mariana arc along the Mariana Trench. The Boso triple junction is located at between the Japan Trench and the Mariana Trench, and the southeastern end of the Sagami Trough where the Philippine Sea Plate subducts beneath northeastern Japan. It is thus a trench-trench-trench type triple junction. For the purpose of understanding the interaction between three plates and its effect to the Pacific Plate, we have performed a passive and active seismic experiment near the Boso triple junction in the far northwestern part of the Pacific plate. We deployed 10 Ocean Bottom Seismometers (OBSs) equipped with a three-componet 1Hz geophone mounted on gimbabl systems on KH09-3 cruise of R/V Hakuho-maru on July 2009, and recovered the OBSs by using M/V Shinchou-maru on October 2010.During the KH09-3 cruise, we shot by using an airgun array (6000 cubic inch in total) during 18 hours on three profiles. We obtained 442days' seismic data from July 29, 2009 to October 13, 2010 in the experiment. More than 2000 earthquakes were detected, and the foci form some clusters.

  12. Role of the eastern California shear zone in accommodating Pacific-North American plate motion

    SciTech Connect

    Dokka, R.K.; Travis, C.J. )

    1990-08-01

    The newly recognized Eastern California shear zone (ECSZ) of the Mojave Desert-Death Valley region has played a major, but previously underappreciated role in accommodating the dextral shear between the Pacific and North American plates in late Cenozoic time. Comparison of integrated net slip along the shear zone with motion values across the entire transform boundary indicates that between 9% and 23% of the total relative plate motion has occurred along the ECSZ since its probably inception {approximately}10-6 Ma. Long-term integrated shear along the ECSZ (6-12 mm yr{sup {minus}1}) is similar to historic measurements (6.7 {plus minus} 1.3 mm yr{sup {minus}1}). Time-space patterns of faulting suggest that shear was concentrated in the eastern part of the Mojave Desert block and Death Valley during late Miocene and early Pleistocene time, but that the locus of faulting in the south-central Mojave jumped westward between 1.5 and 0.7 Ma.

  13. Microstructure and Phase Constitution Near the Interface of Explosively Welded Aluminum/Copper Plates

    NASA Astrophysics Data System (ADS)

    Paul, Henryk; Lity?ska-Dobrzy?ska, Lidia; Pra?mowski, Mariusz

    2013-08-01

    The microstructure changes and the phase constitution within the layers close to the bonding interface strongly influence the properties of bimetallic strips. In this work, the layers near the interface of explosively welded aluminum and copper plates were investigated by means of microscopic observations, mostly with the use of transmission electron microscopy (TEM) equipped with energy dispersive spectrometry (EDX). The study was focused on the identification of the intermetallic phases, the possible interdiffusion between the copper and the aluminum, and the changes in the dislocation structure of the parent plates. In macro-/mesoscale, the interfaces were outlined by a characteristic sharp transition indicating that there was no mechanical mixing between the welded metals in the solid state. In micro-/nanoscale, the layers adhering to the interface show typical deformed microstructure features, i.e., structure refinement, elongated dislocation cells, slip bands, and microtwins (in copper plate). The internal microstructure of the intermetallic inclusion is composed mostly of dendrites. The electron diffractions and TEM/EDX chemical composition measurements revealed three crystalline equilibrium phases of the ?-Al4Cu9, ?-AlCu, and ?-Al2Cu type (the last one was dominant). However, most of the observed phases of the general Cu m Al n type (also crystalline) do not appear in the equilibrium Al-Cu phase diagram. Inside the intermetallic inclusions, no significant regularity in the phase distribution with respect to the parent sheets was observed. Therefore, it was concluded that the processes occurring in the melt determined their local chemical composition.

  14. Bending-related Topographic Structures of the Subducting Plate in the Northwestern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nakanishi, M.; Manabe, I.; Oikawa, M.

    2012-12-01

    We present the elongated topographic structures associated with bending of the subducting oceanic plate along the western Kuril, Japan and Izu-Ogasawara trenches using multibeam bathymetric data. The trench-outer rise earthquake near the Japan Trench occurred in the same day after the 2011 Tohoku Earthquake. Several studies pointed out high occurrence probability of trench-outer rise earthquake after the 2011 Tohoku Earthquake in near future. Trench-outer rise earthquakes occur by reactivation or creation of normal faults caused as the oceanic lithosphere approaches a subduction zone and bends into the deep-sea trench. Bending-related faults in the oceanward trench slope are ubiquitous structures of oceanic plates incoming to trenches. In general, the faults are thought to be formed parallel or subparallel to the bending axis of the incoming plate, namely the trench axis. Oceanward slopes of several trenches have bending-related structure with a strike different from the trench axes (Masson, 1991; Kobayashi et al., 1998; Ranero et al., 2003). In these areas, abyssal hill fabric was reactivated instead of the creation of new faulting parallel to the trench axis. The Mesozoic Pacific Plate is subducting along the Kuril, Japan, Izu-Ogasawara, and Mariana trenches (Nakanishi et al. 1992). Kobayashi et al. (1998) investigated the bending-related structures of the oceanward trench slope of the western Kuril and northern Japan trenches using the multibeam data. They concluded that the abyssal hill fabric is revalidated when abyssal hill fabric trend within 30 degree of trench axes. To examine controlling factors for strikes of bending-related structures, it is indispensable to describe oceanic spreading fabric and to identify magnetic anomaly lineations. The oceanic spreading fabric consists of inherited abyssal hill fabric and other preexisting weak zones related to seafloor spreading process, which are fracture zones, non-transform offsets, and so on. The new bathymetric map demonstrated that most of bending-related topographic structures exist in the oceanward trench slopes deeper than 5600 m. The map revealed that bending-related topographic structures are developed parallel to the trench axis or inherited oceanic spreading fabric. Detailed identification of magnetic anomalies near the Japan Trench revealed curved lineations and discontinuity of lineations associated with propagation ridges. Comparison between the detailed bathymetric and magnetic anomaly lineation maps elucidated that abyssal hill fabrics were reactivated where the angle between abyssal hill fabrics and trench axis is less than about 30 degree.

  15. Geometric Evolution of a Plate Interface-Branch Fault System: Its Effect on Tectonics in Himalaya

    NASA Astrophysics Data System (ADS)

    Takada, Y.; Matsu'Ura, M.

    2002-12-01

    The collision between India and Eurasia is still going on in Himalaya. The present convergence rate between the Indian and the Eurasian plates has been estimated as 50 mm/yr. About 40 % of the total convergence rate is consumed at the collision boundary along the Himalayas by the subduction of the Indian plate beneath the Eurasian plate. The plate boundary fault system in Himalaya is characterized by a large-scale ramp beneath the high Himalayas and a series of thrust-type branch faults. The long-term duration of steady slip along the fault system has caused crustal deformation in Himalaya. The essential point is that the geometry of the fault system changes with time because of the internal deformation caused by the slip of the fault system itself. Therefore, it is necessary to reveal this feedback mechanism to understand the topographic evolution process of the Himalayas. In this study, the interaction between the Indian and the Eurasian plates is represented by steady slip along an interface that divides a stratified elastic-viscoelastic half-space into two blocks. The geometric evolution of the fault system is simulated by considering the changes in fault geometry with time caused by internal deformation. Through numerical simulations we revealed the fundamental properties of geometric evolution of faults. When the plate interface has a ramp, the ramp moves horizontally toward the hanging wall side at a half of the plate convergence rate. The offset of the ramp decreases with time. When the plate interface has an thrust-type branch fault, we can find the accelerative increase in dip-angle of the branch fault. Since the branch fault with a steeper dip-angle is harder to consume the horizontal convergence, we may conclude that the increase in dip-angle results in the cessation of slip along the branch fault at last. The shallower the depth of the branching point is, the larger the increase rate of the dip-angle is. It means that the branch fault with a shallow branching point can not produce the large-scale mountain range, because large amount of slip can not be accommodated by the branch fault.Incorporating these simulation results into geological observations, we propose a scenario on the tectonic evolution of the Himalayas in the last 30 Myr.

  16. A new GPS velocity field for the Pacific Plate - Part 2: implications for fault slip rates in western California

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Márquez-Azúa, Bertha; Cabral-Cano, Enrique

    2014-12-01

    Lower and upper bounds for present deformation rates across faults in central California between the San Andreas Fault and Pacific coast are estimated from a new Global Positioning System (GPS) velocity field for central, western California in light of geodetic evidence presented in a companion paper for slow, but significant deformation within the Pacific Plate between young seafloor in the eastern Pacific and older seafloor elsewhere on the plate. Transects of the GPS velocity field across the San Andreas Fault between Parkfield and San Juan Buatista, where fault slip is dominated by creep and the velocity field thus reveals the off-fault deformation, show that GPS sites in westernmost California move approximately parallel to the fault at an average rate of 3.4 ± 0.4 mm yr-1 relative to the older interior of the Pacific Plate, but only 1.8 ± 0.6 mm yr-1 if the Pacific Plate frame of reference is corrected for deformation within the plate. Modelled interseismic elastic deformation from the weakly coupled creeping segment of the San Andreas Fault is an order-of-magnitude too small to explain the southeastward motions of coastal sites in western California. Similarly, models that maximize residual viscoelastic deformation from the 1857 Fort Tejon and 1906 San Francisco earthquakes mismatch both the rates and directions of GPS site motions in central California relative to the Pacific Plate. Neither thus explains the site motions southwest of the San Andreas fault, indicating that the site motions measure deformation across faults and folds outboard of the San Andreas Fault. The non-zero site velocities thus constitute strong evidence for active folding and faulting outboard from the creeping segment of the San Andreas Fault and suggest limits of 0-2 mm yr-1 for the Rinconada Fault slip rate and 1.8 ± 0.6 to 3.4 ± 0.4 mm yr-1 for the slip rates integrated across near-coastal faults such as the Hosgri, San Gregorio and San Simeon faults.

  17. Investigation on the Interface Morphologies of Explosive Welding of Inconel 625 to Steel A516 Plates

    SciTech Connect

    Mousavi, S. A. A. Akbari; Zareie, H. R.

    2011-01-17

    The purpose of this study is to produce composite plates by explosive cladding process. This is a process in which the controlled energy of explosives is used to create a metallic bond between two similar or dissimilar materials. The welding conditions were tailored through parallel geometry route with different operational parameters. In this investigation, a two-pronged study was adopted to establish the conditions required for producing successful solid state welding: (a) Analytical calculations to determine the weldability domain or welding window; (b) Metallurgical investigations of explosive welding experiments carried out under different explosive ratios to produce both wavy and straight interfaces. The analytical calculations confirm the experimental results. Optical microscopy studies show that a transition from a smooth to wavy interface occurs with an increase in explosive ratio. SEM studies show that the interface was outlined by characteristic sharp transition between two materials.

  18. The August and October, 2008 earthquake swarms on the Explorer/Pacific plate boundary

    NASA Astrophysics Data System (ADS)

    Czoski, P. A.; Trehu, A. M.; Williams, M. C.; Dziak, R. P.; Embley, R. W.

    2011-12-01

    In August and October of 2008, earthquake swarms occurred on the Explorer/Pacific plate boundary. The August swarm lasted for approximately 4 days. Seventy-five earthquakes were reported by the Canadian National Seismograph Nework (CNSN), with the largest having a magnitude of 5.9. The U.S. Navy's Sound Surveillance System (SOSUS) hydrophones reported 148 earthquakes. Over 250 earthquakes were recorded on the Central Oregon Locked Zone Array (COLZA), a temporary array of 15 ocean bottom seismometers (OBS) and hydrophones. The October swarm lasted about 2 days with only one reported CNSN magnitude 4.4 earthquake. This event was also observed with the COLZA network. SOSUS reported 119 earthquakes over the course of two days. In this poster, we use the COLZA T-phase data to better understand the tectonic significance of these swarms. T-phases are generated by earthquakes and converted to acoustic energy at the seafloor. We used the ANSS magnitudes to calibrate an empirical magnitude scale for maximum amplitudes handpicked from the COLZA T-phase observations. This enabled us to lower the magnitude threshold to 2.8. A b-value of 0.78 was obtained for the August swarm suggesting that it may be a tectonic event rather then a magmatic one. Focal mechanisms reported by the Harvard CMT catalog for 3 of the largest events also support strike-slip motion. The reported SOSUS hypocenter locations indicate a linear NE/SW trend west of and parallel to the Explorer Ridge while the ANSS locations are very scattered but suggest a northwest/southeast trend in line with but east of the Dellwood-Revere transform fault. To obtain better-constrained locations, we plan to relocate the events and COLZA T-phase data using cross-correlation techniques developed to locate seismic tremor. We expect the COLZA data will allow us to determine whether activity was primarily focused along the Explorer Ridge axis, along the Dellwood-Revere transform, or within the plate. This investigation could provide us with new insight into the evolution and possible fragmentation of the Explorer Plate.

  19. Origin and evolution of marginal basins of the NW Pacific: Diffuse-plate tectonic reconstructions

    E-print Network

    Xu, Junyuan; Ben-Avraham, Zvi; Yu, Ho-Shing

    2012-01-01

    Formation of the gigantic linked dextral pull-apart basin system in the NW Pacific is due to NNE- to ENE-ward motion of east Eurasia. This mainly was a response to the Indo-Asia collision which started about 50 Ma ago. The displacement of east Eurasia can be estimated using three aspects: (1) the magnitude of pull-apart of the dextral pull-apart basin system, (2) paleomagnetic data from eastern Eurasia and the region around the Arctic, and (3) the shortening deficits in the Large Tibetan Plateau. All the three aspects indicate that there was a large amount (about 1200 km) of northward motion of the South China block and compatible movements of other blocks in eastern Eurasia during the rifting period of the basin system. Such large motion of the eastern Eurasia region contradicts any traditional rigid plate tectonic reconstruction, but agrees with the more recent concepts of non-rigidity of both continental and oceanic lithosphere over geological times. Based on these estimates, the method developed for resto...

  20. Three-dimensional secondary surface geomorphology of submarine landslides on northwest Pacific plate guyots

    NASA Astrophysics Data System (ADS)

    Smoot, N. Christian; King, Robert E.

    1993-01-01

    Slump and debris slides form on seamounts as they grow, age, and are transported across the sea floor. Slump scars, evident as amphitheater headwalls, are a good morphological indicator where a landslide has occurred. Radical changes in the lower flank slope angles are also good indicators. Debris flows can be surmised by hummocky topography, with the larger blocks being nearer the main edifice. A cursory inspection of the Pacific plate from younger to older shows: (1) the Hawaiian-Emperor Ridge from Loihi to Suiko at 65 Ma, where the lower flank slopes increase with age, (2) Mammerickx seamount in the Mapmakers on 140 Ma crust, out of the fractured region, still showing moats and having no sign of landslides, (3) Castor and Pollux guyots of the Michelson Ridge on 150 Ma crust, where the debris field size is added to or overprinted by later volcanics, to (4) Hunk, Jennings, and Jaybee guyots in the Marcus-Wake seamounts on 160 Ma crust, where later fracture zone formation may have helped form landslides. None of the older seamounts have been dated. Three-dimensional views aid in the location and description of landslides.

  1. On gravity from SST, geoid from SEASAT, and plate age and fracture zones in the Pacific

    NASA Technical Reports Server (NTRS)

    Marsh, B. D.; Marsh, J. G.; Williamson, R. G.

    1983-01-01

    Data from an additional 50 satellite-to-satellite tracking (SST) passes were combined with earlier measurements of the high degree and order (n, m, 12) gravity in the central Pacific. A composite map was produced which shows good agreement with conventional GEM models. Data from the SEASAT altimeter was reduced and found to agree well with both the SST and the GEM fields. The maps are dominated especially in the east, by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Further comparison with regional bathymetric data shows a remarkably close correlation with plate age. Each anomaly band is framed by those major fracture zones having large offsets. The regular spacing of these fractures seems to account for the fabric in the gravity fields. Other anomalies are accounted for by hot spots. The source of part of these anomalies is in the lithosphere itself. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantel without complete thermal equilibration is considered.

  2. A revised estimate of Pacific-North America motion and implications for Western North America plate boundary zone tectonics

    NASA Technical Reports Server (NTRS)

    Demets, Charles; Gordon, Richard G.; Stein, Seth; Argus, Donald F.

    1987-01-01

    Marine magnetic profiles from the Gulf of Californa are studied in order to revise the estimate of Pacific-North America motion. It is found that since 3 Ma spreading has averaged 48 mm/yr, consistent with a new global plate motion model derived without any data. The present data suggest that strike-slip motion on faults west of the San Andreas is less than previously thought, reducing the San Andreas discrepancy with geodetic, seismological, and other geologic observations.

  3. Using aftershocks to Image the Subducting Pacific Plate in a Region of Deep Slow Slip, Hikurangi Margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Jacobs, K. M.; Hirschberg, H.; Louie, J. N.; Savage, M. K.; Bannister, S. C.

    2014-12-01

    We present seismic migrations using aftershocks of two M>6 earthquakes as sources. The Southern Cook Strait earthquake sequence, beginning on 19 July 2013, included the 21 July M=6.5 and 16 August M=6.6 2013 earthquakes, which were the largest shallow earthquakes to strike the Wellington region since 1942. Following the two largest earthquakes we began the Seddon Earthquake Aftershock Structural Investigation (SEASI) and deployed a line of 21 seismometers stretching approximately 400 km along the strike of the Hikurangi subduction zone in order to use aftershocks to illuminate the structure of the subducted Pacific slab. The SEASI line ties into the SAHKE line, which was an array of up to 900 seismometers that recorded air gun and explosion shots in deployments from 2009-2011. The SAHKE project characterized the structures perpendicular to the strike of the subduction zone. Our results use the SAHKE line as a starting point and look for strike-parallel variations in the depth of the Moho and other structures. Previous studies have suggested potential changes along strike in this region, and deep slow slip events (> 35 km) are also observed north of Wellington, further indicating that variation in properties exists along slab strike. We have used 246 M > 3 earthquakes that occurred from September 2013 through January 2014 to create common receiver gathers. Multicomponent prestack depth migration of these receiver gathers, with operator antialiasing control and prestack coherency filtering, produces reflectivity sections using a 1-D velocity model derived from the SAHKE project. Relocation of aftershocks of the Seddon earthquakes using the deployment of a temporary array by New Zealand GeoNet facilitates the migration. An initial P-P migration shows a north-dipping reflector at 15-25 km depth under the earthquake sequence, and suggests the Moho at 20-25 km depth. From Wellington, a reflector dips very gently south from 25-35 km depth, which is probably the slab interface. These results are helping to build 3-D information about the plate interface. We hope that this will help us to understand future hazards posed by subduction thrust earthquakes in this region, and the feeding system for deep slow-slip earthquakes.

  4. North America-Pacific plate boundary, an elastic-plastic megashear - Evidence from very long baseline interferometry

    NASA Technical Reports Server (NTRS)

    Ward, Steven N.

    1988-01-01

    Data obtained by Mark III VLBI measurements of radio signals from permanent and mobile VLBI sites for 5.5 years of observations, starting in October 1982, were used to derive a picture of the earth crust deformation near the North America-Pacific plate boundary. The data, which included the vector positions of the VLBI sites and their rate of change, were used for comparison with a number of lithospheric deformation models based upon the concept that the motions of points near the North America-Pacific plate boundary are a linear combination of North America and Pacific velocities. The best of these models were found to fit 95 percent of the variance in 139 VLBI length and transverse velocity observations. Instantaneous shear deformation associated with plate tectonics is apparently developing in a zone 450 km wide paralleling the San Andreas Fault; some of this deformation will be recovered through elastic rebound, while the rest will be permanently set through plastic processes. Because the VLBI data have not been collected for a significant fraction of the earthquake cycle, they cannot discriminate between elastic and plastic behaviors.

  5. Pacific Plate Apparent Polar Wander and Latitudinal Shift of the Hawaiian Hotspot: A Brief Review and Future Prospects

    NASA Astrophysics Data System (ADS)

    Gordon, R. G.

    2005-05-01

    Except for young volcanic islands, the Pacific plate is largely lacking outcrop amenable to traditional paleomagnetic analysis. As a result, a wide variety of alternative methods have been developed for estimating pole positions including analysis of the magnetic anomalies over seamounts ("seamount poles"), shape analysis of magnetic anomalies due to seafloor spreading ("skewness poles"), analysis of the amplitudes of magnetic anomalies due to seafloor spreading, analysis of azimuthally unoriented piston cores and deep-sea drilling cores in both sedimentary and igneous rocks, and analysis of equatorial sediment facies. In the 1970s, studies of seamount poles, of skewness, and of equatorial sediment facies all provided strong evidence for northward motion of the Pacific plate, in general agreement with the northward motion of the Pacific plate predicted if it is assumed that the hotspots are fixed relative to the spin axis. Beginning in about 1980, however, strong evidence was obtained that the northward motion of the Pacific plate relative to the spin axis was less than its northward motion relative to the Hawaiian and other hotspots, implying a southward drift of the Hawaiian hotspot. Results from DSDP Leg 55 first demonstrated southward motion of the Hawaiian hotspot [Kono 1980, Jackson, Koizumi et al. 1980]. Morgan [1981] showed that paleomagnetic poles and hotspot tracks from the Indian and Atlantic Oceans (and bordering continents) predicted this southward motion if the Pacific hotspots are fixed relative to those in the Indo-Atlantic, while both move together relative to the spin axis. This coherent motion of global hotspots can be interpreted as the result of true polar wander. Gordon & Cape [1981] and Gordon [1982] analyzed equatorial sediment facies, published piston core paleomagnetic data, and skewness data. They showed that the data were mutually consistent and indicated southward motion of the Hawaiian hotspot relative to the spin axis consistent with Morgan's predictions. Since then, the apparent polar wander of the Pacific plate has been elaborated in considerably greater detail. Here I concentrate on the results from skewness. Because the ages of the magnetic anomalies analyzed are unambiguous and automatically known to the nearest polarity chron, the ages of skewness poles are precisely known. The geometry of spreading on the Pacific plate during Cenozoic and Late Cretaceous time enables the estimation of poles with very compact confidence regions. Poles have been determined for many different anomalies and give a detailed, but far from complete, view of Pacific plate apparent polar wander since 83 Ma. In contrast, results from igneous rocks obtained by deep sea drilling are far sparser, less accurate, and give only paleolatitudes and not unique poles. The data are nevertheless useful, especially for time intervals lacking magnetic reversals (i.e., the Cretaceous Normal Polarity Superchron) and to provide an independent test of the results from skewness and other approaches. These independent tests reveal a high level of consistency with skewness results, strongly supporting the usefulness and reliability of skewness analysis.

  6. The Magellan seamount trail: implications for Cretaceous hotspot volcanism and absolute Pacific plate motion

    NASA Astrophysics Data System (ADS)

    Koppers, Anthony A. P.; Staudigel, Hubert; Wijbrans, Jan R.; Pringle, Malcolm S.

    1998-11-01

    The Magellan Seamount Trail (MST) delineates a northwest trending chain of four Cretaceous guyots in the West Pacific Seamount Province (WPSP). Seamount morphology, 40Ar/ 39Ar geochronology and Sr-Nd-Pb geochemistry of the MST provides evidence for a hotspot origin between the Samoa, Rarotonga and Society hotspots of the South Pacific Isotopic and Thermal Anomaly (SOPITA). The MST yields an excellent linear age progression of 47.6±1.6 mm/yr ( r2=1.000; MSWD = 0.23; 1 ? SE) including Vlinder guyot (95.1±0.5 Ma, n=5; 2 ? SD), Pako guyot (91.3±0.3 Ma, n=3) and Ioah guyot (87.1±0.3 Ma, n=2). The MST also exhibits a small range in Sr-Nd-Pb isotopic compositions indicating enriched mantle sources with an affinity of EMI. Nevertheless, three volcanic events are found out of sequence with linear MST hotspot volcanism: (1) an independent volcanic pedestal was formed 4-7 Myr before shield-volcanism started at Vlinder guyot, (2) a post-erosional volcanic cone was formed at least 20-30 Myr after drowning of Vlinder guyot, and (3) Ita Mai Tai guyot (118.1±0.5 Ma, n=3) was formed 34-36 Myr before the MST hotspot arrived at the predicted location of this guyot. By identifying and ruling out discordant volcanic events, we can use the age progression in MST to test the fixity of its hotspot. When presuming the fixed hotspot hypothesis, the local age progressions of the MST (47.6±1.6 mm/yr) and the copolar Musicians seamount trail (55.8±6.4 mm/yr) are not compatible with their 100-80 Ma Euler pole. We investigate two options: (1) acceptance of a `forced' Euler pole obeying the hotspot hypothesis by using both the age progressions and the azimuths of the studied seamount trails, or (2) acceptance of a `best-fit' Euler pole by using the azimuths of the studied seamount trail exclusively. In the first option, the angular speed of the Pacific plate during the 100-80 Ma stage pole is calculated at 0.502±0.017°/Myr. In the second option, the `best-fit' Euler pole is found approximately 35° different from the `forced' Euler pole. We argue that the observed age progressions can only be reconciled with the `best-fit' pole when allowing for the relative movement of the MST and Musicians mantle plumes with respect to one another. The calculated maximum velocity component parallel to the line of age progression could then be as much as 23 mm/yr for the mantle plumes — when assuming one fixed hotspot in this alternate model.

  7. Slab break-off related to the Pacific-Izanagi ridge and the 50 Ma plate reorganization

    NASA Astrophysics Data System (ADS)

    Whittaker, J. M.; Seton, M.; Flament, N.; Gurnis, M.; Talsma, A. S.; Müller, R. D.

    2011-12-01

    A hemisphere-wide plate reorganization occurred approximately 50 million years ago, causing a plethora of tectonic events in the Pacific, Indian and Atlantic oceans. The ultimate driver of this reorganization, either a plate tectonic/top-down or a mantle flow/bottom-up mechanism, remains unresolved. Top-down mechanisms often invoke a dramatic change in slab pull due to the arrival of a mid ocean ridge or aseismic ridge at a subduction zone. Bottom-up mechanisms require sudden lateral or vertical changes in mantle flow. We use a combination of surface geology, plate reconstructions, forward geodynamic models and seismic tomography to investigate the effect a slab break-off event related to the intersection of the Pacific-Izanagi ridge and the East Asian subduction zone on the 50 Ma plate reorganization. The intersection of an active mid ocean ridge with a subduction zone commonly results in the formation of a slab window. Surface manifestations of an underlying slab window are observed in the geology of southern and central Japan including: the cessation of a major accretion phase in the late Cretaceous; elevated geothermal gradients and heat flux around 55 Ma; and the emplacement of the Okitsu Melange due to underlying hot, buoyant material at 55 Ma. The cessation of granitic plutonism in Korea suggests that subduction along the margin terminated at around 60-50 Ma before restarting again ~42 Ma. We independently reconstructed the now subducted ocean floor in Panthalassa based on the magnetic lineations preserved in the ocean floor in the western Pacific and following a simple, symmetrical spreading regime with inferred intermediate spreading rates. Our plate reconstructions result in the progressively southward arrival of the Pacific-Izanagi ridge parallel to the East Asian margin between 60-50 Ma, consistent with the geological observations listed above. In addition, we carry out a series of forward geodynamic models with imposed surface plate velocities, lithospheric age and assimilated subducted slabs. Our models result in slab break-off along the East Asian margin coincident with the 50 Ma plate reorganization. We compare the present-day mantle temperature field predicted by our models to seismic tomography images over East Asia. These images reveal a break in the continuity of slab material in the mid-mantle, compatible with the slab break-off observed in both the geological record and geodynamic models. Our results suggest that the 50 Ma hemisphere-wide plate reorganization could have been triggered by a plate-driven mechanism rather than by a change in mantle flow alone. We suggest that the major change in direction of Pacific mantle flow may have been a consequence of a cessation of the long-lasting subduction along the East Asian subduction zone around 50 Ma.

  8. Anatomy of the western Java plate interface from depth-migrated seismic images

    USGS Publications Warehouse

    Kopp, H.; Hindle, D.; Klaeschen, D.; Oncken, O.; Reichert, C.; Scholl, D.

    2009-01-01

    Newly pre-stack depth-migrated seismic images resolve the structural details of the western Java forearc and plate interface. The structural segmentation of the forearc into discrete mechanical domains correlates with distinct deformation styles. Approximately 2/3 of the trench sediment fill is detached and incorporated into frontal prism imbricates, while the floor sequence is underthrust beneath the d??collement. Western Java, however, differs markedly from margins such as Nankai or Barbados, where a uniform, continuous d??collement reflector has been imaged. In our study area, the plate interface reveals a spatially irregular, nonlinear pattern characterized by the morphological relief of subducted seamounts and thicker than average patches of underthrust sediment. The underthrust sediment is associated with a low velocity zone as determined from wide-angle data. Active underplating is not resolved, but likely contributes to the uplift of the large bivergent wedge that constitutes the forearc high. Our profile is located 100 km west of the 2006 Java tsunami earthquake. The heterogeneous d??collement zone regulates the friction behavior of the shallow subduction environment where the earthquake occurred. The alternating pattern of enhanced frictional contact zones associated with oceanic basement relief and weak material patches of underthrust sediment influences seismic coupling and possibly contributed to the heterogeneous slip distribution. Our seismic images resolve a steeply dipping splay fault, which originates at the d??collement and terminates at the sea floor and which potentially contributes to tsunami generation during co-seismic activity. ?? 2009 Elsevier B.V.

  9. Upper Plate Deformation is Dominated by Varying Interface Coupling in the Chilean Subduction Context

    NASA Astrophysics Data System (ADS)

    Vigny, C.; Socquet, A.; Madariaga, R.; Ruegg, J.; Campos, J.; Barrientos, S.

    2008-12-01

    It has been almost two decades now that GPS has been used to measure plate tectonics and quantify plate deformation. In South America, the debate rapidly focused on the motion of the Nazca plate relative to the South America plate. Space geodesy allows to compare plate motions averaged over a few years to plate motion averaged over several million of years. Since the initial work of (Larson et al., 1997) which found similar rates, it is well known now (eg: Norabuena et al, 1998; Norabuena et al, 1999; Angermann et al., 1999; Altamimi et al., 2002; Kendrick et al, 2003; Vigny et al, 2008) that in fact the present day motion of the Nazca plate is around 15% slower than its Nuvel-1A estimate. This finding has the important consequence that along the South American margin, instead of nearing 8 cm/yr, today's subduction rate ranges from 5.5 cm/yr in Equator to 7 cm/yr in central Chile, before it decreases again to 6.5 cm/yr in southern Chile. Part of this convergence rate is taken up by permanent strain contributing to the building of the Andes, but most of it generates elastic deformation recovered during the seismic cycle with an average of one M=8 event every ten years and at least one M>8.7 per century in what corresponds to the Chilean portion of the Nazca subduction. Surface deformation is representative of these processes and GPS measurements made in the area aim at quantifying the different contributions and defining the style of deformation. Up to now, two different families of models have been presented: 2-plates model, involving homogeneous medium where the slab geometry varies with latitude and depth, (Klotz et al., 2001; Khazaradze et al., 2003); 3-plates model involving a rigid sliver between the 2 main plates (Kendrick et al., 2003; Brooks et al, 2003). Steady state velocities predicted by these models differ at the cm/yr level in places and GPS measurements should allow to discriminate easily between them. However, recent measurements we carried out on small scale dense networks in Chile in the vicinity of the trench (Concepion - 36° S, Coquimbo - 30° S, Antofagasta - 22° S) show that the deformation exhibits very different patterns in distinct areas and abrupt changes with latitude. We demonstrate that to model these patterns with a full coupling on the trench is not possible everywhere, and following others, we conclude that coupling must be varying on the subduction interface, both with depth and along strike, and can reach value as low as 40% regionally and even less locally. Moreover, these low-coupling areas could correspond to transient deformation associated to the seismic cycle. This signal completely dominates the deformation patterns we measured at the surface over the last decade, and renders extremely difficult to detect the permanent deformation not taken up by the recoverable elastic deformation or even to simply quantify the style of deformation.

  10. Rayleigh wave tomography beneath the oceanic and continental margin of the North-America and Pacific plate boundary.

    NASA Astrophysics Data System (ADS)

    Rathnayaka, S.; Escobar, L., Sr.; Weeraratne, D. S.; Kohler, M. D.

    2014-12-01

    The inception of the San Andreas fault, a transform plate boundary system, is the result of subduction of the EPR spreading center, rifting of the Borderland in the Miocene and subsequent plate rotation that is ongoing today. To address the lack of offshore data at this plate boundary, we use Rayleigh waves recorded by a marine seismic array of 34 ocean bottom seismometers (OBS) to tomographically image phase velocities beneath the oceanic and continental margin of the North America-Pacific plate boundary. The OBSs were deployed as part of the ALBACORE project offshore southern California on 18-32 Ma seafloor. The marine seismic array recorded data from August 2010 to 2011 and are combined with 82 land stations from the CISN network. We analyze ~100 teleseismic events at distances ranging from 30° to 120° for Mw ? 5.9, filtered at periods between 16 and 78 s. Strong structural gradients are present across this plate margin; therefore, we perform amplitude corrections for OBS stations that account for velocity variations in water, sediment layer, crustal thickness, marine fossil layers and lithospheric thickness as a function of seafloor age. We use a surface wave inversion that considers a two plane wave method and perform a grid search for inversion parameters. Our results indicate that averaged phase velocities are 1.3% lower than previous studies for the seafloor age bin 20-52 Ma. Phase velocities at lithospheric depths are 5% higher in the oceanic mantle compared to the continental mantle indicating compositional and structural differences due to formation history in the two tectonic environments. Anisotropy in the offshore region of our study is consistent with Pacific plate motion, N 78.5? W, except for periods longer than 40 s in the Borderland where anisotropy demonstrates N-S alignment. The Borderland, a transitional region between the continental and oceanic plate margin where rotation of the transverse ranges involved rifting and extension, shows unique velocity and anisotropic structure compared to the land and deep seafloor regions.

  11. Heat flow anomaly on the seaward side of the Japan Trench associated with deformation of the incoming Pacific plate

    NASA Astrophysics Data System (ADS)

    Yamano, Makoto; Hamamoto, Hideki; Kawada, Yoshifumi; Goto, Shusaku

    2014-12-01

    Extensive heat flow measurements were conducted on the seaward side of the Japan Trench for investigation of the extent and the origin of high heat flow previously found on the incoming Pacific plate. The obtained data combined with the existing data showed that high and variable heat flow values are pervasively distributed seawards of the northern half of the trench and within about 150 km of the trench axis. In this anomalous zone, the average heat flow is 60 to 70mW/m2, appreciably higher than the value typical for the seafloor age of about 135 m.y. The occurrence of the anomalous heat flow along the trench indicates that it results from processes closely related to deformation of the incoming plate. Heating by intra-plate "petit-spot" volcanism and/or fluid flow along normal faults developed on the trench slope may yield local heat flow peaks but cannot raise regional average heat flow. The most probable cause of the observed widespread anomalous heat flow is efficient vertical heat transport by hydrothermal circulation in a permeable layer in the oceanic crust, which is gradually developed by fracturing due to plate bending. Similar heat flow and temperature structure anomalies on the seaward side of the trench may exist in other subduction zones.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Real feature of seismicity around Palau trench region, western Pacific: Is Palau trench aseismic silent plate boundary?

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.; Shito, A.; Tanaka, S.; Suetsugu, D.

    2012-12-01

    Palau islands locate around plate converging zone in the western Pacific region. In the east off the Palau islands, obvious trench topography is developed whose bathymetry reaches about 6000 meters. Palau trench locates at the west side of Yap trench. However tectonic activity is quite different in the both trenches. Yap trench has active seismic activity associate with subduction process. Plate motion model shows clear convergent relative motion between Pacific plate and Philippine Sea plate at Yap trench. On the other hand, Palau trench doesn't have active seismicity according to ISC catalogue. In ten years in 2000's, only three small earthquakes are reported in ISC catalogue. Historically any great earthquake also is not reported. Recent plate motion model shows very low convergent motion at Palau trench though developed trench structure. Our group operates broadband seismic station at Palau (station code: PALU) for about 15 years. In our instant monitoring, local earthquakes sometime are recognized. We operated additional stations in Palau islands for six months to detect local earthquake and to locate hypocenters. Our objective of the research is evaluation of real seismicity of Palau region and final major interest is to understand tectonic activity of Palau trench. We install minimum network for hypocenter locating in Koror and Babeldaob islands, Palau that its array dimension is about 20 km. We use broadband seismographs and high resolution data loggers with GPS clock and solar power generators. We succeeded continuous recording without any troubles and clips of mass position. By careful motoring, we pick up greater than 70 local earthquakes in only six months. And we also tried to read the P and S wave arrival times. We succeeded to locate 27 hypocenters. The number of seismic events is much higher than initial estimation. The hypocenters locate east coast side of Palau islands where is trench side. The overview of distribution is parallel to trench. Estimated depth is distributed from 20 to 30 km. The determination is inaccurate and sparse distributed, but simple seismograms mean that these are not shallow crustal event. P and S wave amplitude analysis says that dip-slip type fault mechanism is dominant. This seismic activity may be strongly related with subduction process. These earthquakes are magnitude of 2 to 3. Seismicity of Palau area is much higher than initial estimation based on earthquake catalogue. These results mean that Palau trench has latent active seismic process and suggest that the trench may have convergent plate process than general understanding.

  14. Plate convergence, transcurrent faults and internal deformation adjacent to Southeast Asia and the western Pacific

    NASA Technical Reports Server (NTRS)

    Fitch, T. J.

    1971-01-01

    A model for oblique convergence between plates of lithosphere is proposed in which at least a fraction of slip parallel to the plate margin results in transcurrent movements on a nearly vertical fault which is located on the continental side of a zone of plate consumption. In an extreme case of complete decoupling only the component of slip normal to the plate margin can be inferred from underthrusting. Recent movements in the western Sunda region provide the most convincing evidence for decoupling of slip, which in this region is thought to be oblique to the plate margin. A speculative model for convergence along the margins of the Philippine Sea is constructed from an inferred direction of oblique slip in the Philippine region. This model requires that the triple point formed by the junction of the Japanese and Izu-Bonin trenches and the Nankai trough migrate along the Sagami trough.

  15. Unlocking the Secrets of Slow Slip on the Plate Interface Using Cascadia LFEs

    NASA Astrophysics Data System (ADS)

    Sweet, J. R.; Creager, K. C.; Thomas, T.; Vidale, J. E.; Houston, H.

    2012-12-01

    Low-frequency earthquakes (LFEs) have been associated with tectonic tremor and slow slip on the deep extension of subduction zones (Japan, Cascadia, Alaska, Costa Rica) and major strike-slip faults (SAF). These tiny earthquakes are thought to represent small amounts of slip on the fault interface in places with very high pore fluid pressures and low effective stresses. Tectonic tremor has been shown to often consist of a superposition of many LFEs occurring at nearly the same time. Using data from the 2-year Array of Arrays (AofA) and 6-year CAFE experiments in northern Cascadia, we employ a matched-filter autocorrelation method to find new LFE families. Similar to the method of Brown et al. (GRL, 2008), ours makes use of efficient coding to minimize the significant computational time required. To date, we have identified and located 8 LFE families, all of which are very near the plate interface. By analyzing a 6-year history of individual LFE families, we find several new patterns that vary with downdip distance on the plate interface. The two end-member LFE families (LFE1 - farthest updip, and LFE4 - farthest downdip) illustrate the greatest differences in behavior. The recurrence interval of LFE activity increases updip. LFE1 is only active during major ETS episodes every 12-15 months, while LFE4 repeats every 2 weeks. This observation mirrors that already reported for tremor swarms in Cascadia (Wech et al., 2011, Nature GeoSci.), further supporting the idea that tremor and LFEs are closely linked. In addition, we observe that the duration of the initial burst of activity is longer for updip LFE families than for downdip ones. LFE1 exhibits an initial burst of frenzied activity that lasts ~4 hours, which we interpret to be the passage of the slow-slip rupture front. In contrast, LFE4 has initial bursts that last at most 1 hour (see Creager et al., this session). The different duration of bursts, combined with the different recurrence intervals, suggests that locations farther updip are capable of accumulating and releasing larger amounts of slip than locations farther downdip. This observation may provide insight into how frictional properties vary over the subduction interface. During each of the past 5 ETS episodes, LFE1 was active over a 5-day period following the initial burst. During these 5 days, most of the activity was concentrated in roughly 5 residual bursts (of duration <1hr) that occurred at exponentially increasing recurrence intervals. After 5 days, the residual bursts ceased and no activity was detected until the next ETS episode. In addition, nearly all of the residual bursts occurred during times of favorable tidal shear stress, suggesting that these later bursts occurred in an environment with very low stress such that small tidal fluctuations activate or inhibit slip. In contrast, the initial bursts occurred independently of the tidal stress. For the last 2 ETS episodes, the residual bursts correspond to rapid tremor reversals (RTRs) imaged by the AofA (see Thomas et al., this session). This observation may indicate that RTRs could be modulated and perhaps even triggered by favorable tidal stressing in the extremely low stress region behind the initial slip front. This idea is consistent with the proposal by Houston et al. (2011, Nature GeoSci.) that RTRs are associated with a slip-weakened plate interface.

  16. Localized double-array stacking analysis of PcP: D? and ULVZ structure beneath the Cocos plate, Mexico, central Pacific, and north Pacific

    NASA Astrophysics Data System (ADS)

    Hutko, Alexander R.; Lay, Thorne; Revenaugh, Justin

    2009-03-01

    A large, high quality P-wave data set comprising short-period and broadband signals sampling four separate regions in the lowermost mantle beneath the Cocos plate, Mexico, the central Pacific, and the north Pacific is analyzed using regional one-dimensional double-array stacking and modelling with reflectivity synthetics. A data-screening criterion retains only events with stable PcP energy in the final data stacks used for modelling and interpretation. This significantly improves the signal stacks relative to including unscreened observations, allows confident alignment on the PcP arrival and allows tight bounds to be placed on P-wave velocity structure above the core-mantle boundary (CMB). The PcP reflections under the Cocos plate are well modelled without any ultra-low velocity zone from 5 to 20°N. At latitudes from 15 to 20°N, we find evidence for two P-wave velocity discontinuities in the D? region. The first is ?182 km above the CMB with a ?ln Vp of +1.5%, near the same depth as a weaker discontinuity (<+0.5%) observed from 5 to 15°N in prior work. The other reflector is ?454 km above the CMB, with a ?ln Vp of +0.4%; this appears to be a shallower continuation of the joint P- and S-wave discontinuity previously detected south of 15° N, which is presumed to be the perovskite to post-perovskite phase transition. The data stacks for paths bottoming below Mexico have PcP images that are well matched with the simple IASP91 structure, contradicting previous inferences of ULVZ presence in this region. These particular data are not very sensitive to any D? discontinuities, and simply bound them to be Pacific confirm the presence of a ?15-km thick ultra-low velocity zone (ULVZ) just above the CMB, with ?ln Vp and ?ln Vs of around -3 to -4% and -4 to -8%, respectively. The ULVZ models predict previous S-wave data stacks well. The data for this region indicate laterally varying Vp discontinuities in D?, with one subregion having a ?ln Vp of 0.5% 140 km above the CMB. Beneath the north Pacific, the PcP arrivals are compatible with only weak ULVZ (?ln Vp ? 0 to -3%), and there is a weak D? reflector with ?ln Vp = 0.5%, near 314 km above the CMB. These results indicate localized occurrence of detectable ULVZ structures rather than ubiquitous ULVZ structure and emphasize the distinctiveness between the large low shear velocity province under the central Pacific and circum-Pacific regions.

  17. Ultrasonic wave propagation in reactor pressure vessel cladded interfaces. [Stainless Steel Cladding/Ferritic Steel Plate Interface

    SciTech Connect

    Pereyra, V.; Mould, J.C. Jr. )

    1990-11-01

    This report describes the development and application of ray tracing to the problem of stainless steel cladding on a ferritic steel plate. Such materials are commonly found in components of nuclear power plants. An important goal of the work is to image a crack emanating perpendicular to the interface and to calculate a synthetic A-scan typical of pitch-catch or pulse-echo ultrasonic inspection methods. Ray methods are attractive for rapidly gaining insight into ultrasonic inspection of complex parts because, like finite elements, they are capable of imaging obstacles in the ray path but are less computationally intensive. In the present project, we extend our existing ray code RAYT3D, which we previously applied primarily in geophysics, to transversely isotropic materials such as cladding. There are three goals for this effort. First to document the ray method 3-D formulation for transversely isotropic materials, including all of the ingredients necessary to generate synthetic A-scans from a postulated model. Second, to expand awareness of the advantages of a two-point formulation wherein the ray tracing problem is formulated as a two-point boundary value problem rather than as an initial value or shooting problems as is more commonly encountered. The two-point formulation has a number of advantages, including efficiency, stability, and suitability for use in an inversion loop. Inversion is one possible long-term goal of this work. Finally, we solve a few representative examples, with the hope that readers will recognize a tool which could solve some problems of immediate interest to the NDE community, and direct our attention to those problems. 14 refs., 12 figs., 6 tabs.

  18. First measurement of the displacement rate of the Pacific Plate near the Japan Trench after the 2011 Tohoku-Oki earthquake using GPS/acoustic technique

    NASA Astrophysics Data System (ADS)

    Tomita, Fumiaki; Kido, Motoyuki; Osada, Yukihito; Hino, Ryota; Ohta, Yusaku; Iinuma, Takeshi

    2015-10-01

    The subduction rate of an oceanic plate may accelerate after large earthquakes rupture the interplate coupling between the oceanic and overriding continental plates. To better understand postseismic deformation processes in an incoming oceanic plate, we directly measured the displacement rate of the Pacific Plate near the Japan Trench after the 2011 Tohoku-Oki earthquake using a GPS/acoustic technique over a period of 2 years (September 2012 to September 2014). The displacement rate was measured to be 18.0 ± 4.5 cm yr-1 (N302.0°E) relative to the North American Plate, which is almost twice as fast as the predicted interseismic plate motion. Because the sum of steady plate motion and viscoelastic response to the Tohoku-Oki earthquake roughly accounts for the observed displacement rate, we conclude that viscoelastic relaxation is the primary mechanism responsible for postseismic deformation of the Pacific Plate and that significant subduction acceleration did not occur at least not during the observation period.

  19. Modeling Thermal and Stress Behavior of the Fuel-clad Interface in Monolithic Fuel Mini-plates

    SciTech Connect

    Gregory K. Miller; Pavel G. Medvedev; Douglas E. Burkes; Daniel M. Wachs

    2010-08-01

    As part of the Global Threat Reduction Initiative, a fuel development and qualification program is in process with the objective of qualifying very high density low enriched uranium fuel that will enable the conversion of high performance research reactors with operational requirements beyond those supported with currently available low enriched uranium fuels. The high density of the fuel is achieved by replacing the fuel meat with a single monolithic low enriched uranium-molybdenum fuel foil. Doing so creates differences in the mechanical and structural characteristics of the fuel plate because of the planar interface created by the fuel foil and cladding. Furthermore, the monolithic fuel meat will dominate the structural properties of the fuel plate rather than the aluminum matrix, which is characteristic of dispersion fuel types. Understanding the integrity and behavior of the fuel-clad interface during irradiation is of great importance for qualification of the new fuel, but can be somewhat challenging to determine with a single technique. Efforts aimed at addressing this problem are underway within the fuel development and qualification program, comprised of modeling, as-fabricated plate characterization, and post-irradiation examination. An initial finite element analysis model has been developed to investigate worst-case scenarios for the basic monolithic fuel plate structure, using typical mini-plate irradiation conditions in the Advanced Test Reactor. Initial analysis shows that the stress normal to the fuel-clad interface dominates during irradiation, and that the presence of small, rounded delaminations at the interface is not of great concern. However, larger and/or fuel-clad delaminations with sharp corners can create areas of concern, as maximum principal cladding stress, strain, displacement, and peak fuel temperature are all significantly increased. Furthermore, stresses resulting from temperature gradients that cause the plate to bow or buckle in an unconstrained fuel plate configuration is greatly enhanced in a constrained fuel plate configuration. The sensitivities of the model and input parameters are discussed, along with some overlap of initial experimental observations using as-fabricated plate characterization and post-irradiation examination.

  20. Seismological investigations of the subduction zone plate interface: New advances and challenges

    NASA Astrophysics Data System (ADS)

    Rietbrock, Andreas; Garth, Tom; Hicks, Stephen

    2015-04-01

    In the last decade, huge advances have been made in analysing the slip distribution of large megathrust earthquakes and how slip relates to geodetic locking, shedding light on the character of the seismic cycle in subduction zones. Recently, a number of studies have suggested that at convergent plate boundaries, geodetic locking may be closely related to slip distribution of subsequent large earthquakes, as found recently for the Maule 2010 and Tohoku 2011 earthquakes. However, the physical (e.g. seismic) properties along the subduction zone interface are still poorly constrained, posing a major limitation to our physical understanding of both geodetic locking and earthquake rupture process. Here, we present high-resolution seismic tomography results (P- and S-wave velocity), as well as earthquake locations to make a detailed investigation of seismic properties along the portion of the plate interface that ruptured during the 2010 Maule earthquake. Additionally, to test the robustness of our models, we performed numerous numerical tests including changes to the parameterization, synthetic recovery tests and bootstrap analysis. We find P-wave velocities of about 5.7 km/s at 10 km depth and linearly increasing to 7.5 km/s at a depth of 30 km. Between 30 km and 43 km, P-wave velocities are relatively constant at around 7.5 km/s before a subsequent increase to 8.3 km/s at larger depths (>60 km) is observed. The Poisson's ratio is significantly elevated, at values of up to 0.35 at shallow depths of 10km to 15km, before reaching less elevated values of 0.28-0.29 in the depth range between 20km and 43km. Comparison of these velocities to petrological models shows good agreement below 30 - 50 km depth. At shallower depths though P-wave velocities are significantly lower, which together with the elevated poisons ratio indicates that this portion of the mega thrust is highly hydrated, suggesting that material properties may in part control the seismogenic character of subduction megathrusts Comparison of our findings to other regional tomographic models from other subduction zones worldwide (Japan, Sumatra) shows excellent agreements with our results.

  1. Faunal breaks and species composition of Indo-Pacific corals: the role of plate tectonics, environment and habitat distribution.

    PubMed

    Keith, S A; Baird, A H; Hughes, T P; Madin, J S; Connolly, S R

    2013-07-22

    Species richness gradients are ubiquitous in nature, but the mechanisms that generate and maintain these patterns at macroecological scales remain unresolved. We use a new approach that focuses on overlapping geographical ranges of species to reveal that Indo-Pacific corals are assembled within 11 distinct faunal provinces. Province limits are characterized by co-occurrence of multiple species range boundaries. Unexpectedly, these faunal breaks are poorly predicted by contemporary environmental conditions and the present-day distribution of habitat. Instead, faunal breaks show striking concordance with geological features (tectonic plates and mantle plume tracks). The depth range over which a species occurs, its larval development rate and genus age are important determinants of the likelihood that species will straddle faunal breaks. Our findings indicate that historical processes, habitat heterogeneity and species colonization ability account for more of the present-day biogeographical patterns of corals than explanations based on the contemporary distribution of reefs or environmental conditions. PMID:23698011

  2. Faunal breaks and species composition of Indo-Pacific corals: the role of plate tectonics, environment and habitat distribution

    PubMed Central

    Keith, S. A.; Baird, A. H.; Hughes, T. P.; Madin, J. S.; Connolly, S. R.

    2013-01-01

    Species richness gradients are ubiquitous in nature, but the mechanisms that generate and maintain these patterns at macroecological scales remain unresolved. We use a new approach that focuses on overlapping geographical ranges of species to reveal that Indo-Pacific corals are assembled within 11 distinct faunal provinces. Province limits are characterized by co-occurrence of multiple species range boundaries. Unexpectedly, these faunal breaks are poorly predicted by contemporary environmental conditions and the present-day distribution of habitat. Instead, faunal breaks show striking concordance with geological features (tectonic plates and mantle plume tracks). The depth range over which a species occurs, its larval development rate and genus age are important determinants of the likelihood that species will straddle faunal breaks. Our findings indicate that historical processes, habitat heterogeneity and species colonization ability account for more of the present-day biogeographical patterns of corals than explanations based on the contemporary distribution of reefs or environmental conditions. PMID:23698011

  3. Plastic Creep and Brittle-Ductile Transition in Hydrated Rocks of the Plate Interface

    NASA Astrophysics Data System (ADS)

    Reynard, B.

    2014-12-01

    Geophysical observations suggest that the formation of hydrous phyllosilicate-bearing rocks such as serpentinites favor aseismic slip on the plate interface. I review our current understanding of deformation of serpentines and similar phyllosilicates in the first 100 km of subduction and discuss some pending questions on measurements and modeling of the behavior and properties of the complex serpentinite rocks. Experimental studies suggest that serpentines have low enough mechanical strength to act as a "stabilizer" of stable creep, but the actual strength of serpentinites will depend on the exact nature of the crystallographic structure and fabric of the stable serpentine variety. Low-temperature, flat-layered lizardite has strong anisotropy in strength. Lizardite-serpentinite strength will depend crystal-preferred orientation (CPO), with isotropic texture having high strength (>300 MPa) and foliated serpentinites having small strength (<100 MPa), independent of temperature, pressure, and strain rate. Thus, the transition between brittle and plastic (or stable creep) behavior may result from progressive deformation. High-temperature serpentine antigorite has a complex corrugated-layered structure, and complex deformation modes were evidenced from experimental studies. Mechanical strength shows a strong stress dependence, suggesting dislocation-creep, and low temperature dependence, suggesting plastic behavior. Extrapolation of experimental results to natural strain rates suggests that antigorite-serpentinites have low strength (<100 MPa or lower), and will favor stable-creep. However, the extrapolation relies on mechanical flow laws that may not apply to serpentine. Electron microscopy observations reveals dislocation-like deformation mechanisms that are not sufficient to explain global deformation of antigorite aggregates, and that are likely accompanied by dissolution-precipitation at low natural strain-rates. Establishing reliable flow laws relevant to the subduction interface in the 30-100 km depth range will require further experimental investigations of such mechanisms.

  4. Late cretaceous pelagic sediments, volcanic ASH and biotas from near the Louisville hotspot, Pacific Plate, paleolatitude ?42°S

    USGS Publications Warehouse

    Ballance, Peter F.; Barron, John A.; Blome, Charles D.; Bukry, David; Cawood, Peter A.; Chaproniere, George C.H.; Frisch, Robyn; Herzer, Richard H.; Nelson, Campbell S.; Quinterno, Paula; Ryan, Holly F.; Scholl, David W.; Stevenson, Andrew J.; Tappin, David G.; Vallier, Tracy L.

    1989-01-01

    Dredging on the deep inner slope of the Tonga Trench, immediately north of the intersection between the Louisville Ridge hotspot chain and the trench, recovered some Late Cretaceous (Maestrichtian) slightly tuffaceous pelagic sediments. They are inferred to have been scraped off a recently subducted Late Cretaceous guyot of the Louisville chain. In the vicinity of the Louisville hotspot (present location 50°26?S, 139°09?W; Late Cretaceous location ?42°S, longitude unknown) Late Cretaceous rich diatom, radiolarian, silicoflagellate, foraminiferal and coccolith biotas, accumulated on the flanks of the guyot and are described in this paper. Rich sponge faunas are not described. ?Inoceramus prisms are present. Volcanic ash is of within-plate alkalic character. Isotope ratios in bulk carbonate ?18O ? 2.63 to + 0.85, ?13C + 2.98 to 3.83) are normal for Pacific Maestrichtian sediments. The local CCD may have been shallower than the regional CCD, because of high organic productivity. In some samples Late Cretaceous materials have been mixed with Neogene materials. Mixing may have taken place on the flanks of the guyot during transit across the western Pacific, or on the trench slope during or after subduction and offscraping about 0.5 Ma.

  5. Plate motion

    SciTech Connect

    Gordon, R.G. )

    1991-01-01

    The motion of tectonic plates on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current plate motions, diffuse plate boundaries and the oceanic lithosphere, the relation between plate motions and distributed deformations, accelerations and the steadiness of plate motions, the distribution of current Pacific-North America motion across western North America and its margin, plate reconstructions and their uncertainties, hotspots, and plate dynamics. A comprehensive bibliography is provided. 126 refs.

  6. High Resolution 40Ar/39Ar Geochronology of the Tuvalu Seamount Chain: Implications for Hotspot Longevity and Pacific Plate Motion.

    NASA Astrophysics Data System (ADS)

    Konrad, K.; Finlayson, V. A.; Koppers, A. A. P.; Konter, J.; Jackson, M. G.

    2014-12-01

    The Tuvalu seamount chain is a Mid-Pacific (4-11oS, 175-179oE) linear volcanic chain that was previously poorly sampled. Absolute plate motion (APM) models predict a long-lived relationship with hotspot activity in French Polynesia. The lack of detailed age data therefore results in a key chronologic gap in the geologic history of this hotspot and current APM models. Depending on the set of assumptions employed, previous APM models have disagreed on which known hotspot chain, if any, the Tuvalu volcanoes are associated with. Based on APM modeling and geochemical affinities (HIMU, 206Pb/204Pb > 20), Konter et al. (2008) argue that Rurutu Island (French Polynesia) represents the modern location of the hotspot that contributed volcanism to the Tuvalu seamounts. This model traces the hotspot chain from Rurutu through the region of modern day Samoa, the Tuvalu seamounts, the Gilbert ridge, and into the North & South Wake islands. This hypothesis suggests that a single HIMU mantle reservoir can exist and remain relatively geochemically consistent over 100 Myrs. On the contrary, the Wessel and Kroenke (2008) APM model suggest the Tuvalu seamounts and N & S Wake are unrelated. This model requires the N & S Wake chains to rotate significantly at the young end of the Gilbert Ridge resulting in a current hotspot location around 13-15oS and 156-155oW, away from any known active volcanism. During the summer of 2013, 25 Tuvaluan seamounts and 9 seamounts near the current Samoan chain were dredged onboard the R.V. Roger Revelle (expedition RR1310). Here we present 43 new 40Ar-39Ar ages covering 19 Tuvaluan seamounts and four seamounts within the Samoan hotspot track. These ages provide insights into the contributing hotspot for Tuvaluan volcanism and provide a new reference frame for constraining Pacific APM models. The corresponding chemical analyses for a subset of these seamounts will be presented by Finlayson et al. (this volume). Konter, J. G. et al. One hundred million years of mantle geochemical history suggest the retiring of mantle plumes is premature. Earth and Planetary Science Letters 275, 285-295, doi:10.1016/j.epsl.2008.08.023 (2008) Wessel, P. & Kroenke, L. W. Pacific absolute plate motion since 145 Ma: An assessment of the fixed hot spot hypothesis. Journal of Geophysical Research: Solid Earth (1978-2012) 113 (2008)

  7. Fluid content along the subduction plate interface: how it impacts the long- (and short-) term rheology and exhumation modes

    NASA Astrophysics Data System (ADS)

    Agard, Philippe; Angiboust, Samuel; Guillot, Stéphane; Burov, Evgueni

    2015-04-01

    Over the last decade, many studies based on field, petrological and geophysical evidence have emphasized the link between mineral reactions, fluid release and seismogenesis, either along the whole plate interface (eg., Hacker et al., 2003) or at specific depths (e.g., ~30 km: Audet et al., 2009; ~70-80 km: Angiboust et al., 2012). Although they argue for a crucial influence of fluids on subduction processes, large uncertainties remain when assessing their impact on the rheology of the plate interface across space and time. Kilometer-scale accreted terranes/units in both ancient and present-day subduction zones potentially allow to track changes in mechanical coupling along the plate interface. Despite some potential biases (exhumation is limited and episodic, lasting no more than a few My if any, from prefered depths -- mainly 30-40 and 70-80 km, and there are so far only few examples precisely located with respect to the plate interface) their record of changes in fluid regime and strain localisation is extremely valuable. One striking example of the role of fluids on plate interface rheology during nascent subduction is provided by metamorphic soles (i.e., ~500 m thick tectonic slices welded to the base of ophiolites). We show that their accretion to the ophiolite indeed only happens across a transient, optimal time-T-P window (after < 1-2 My, at 1±0.2 GPa, 750-850°C) associated with fluid release and infiltration, leading to similar effective rheology on both sides (i.e., downgoing crust and mantle wedge). This maximizes interplate mechanical coupling, as deformation gets distributed over a large band encompassing the plate interface (i.e., a few km), and promotes detachment of the sole from the sinking slab. We also show how tectonic slicing during mature subduction likely relates to short-term fluid release and repeated seismicity, based on the Monviso exposures (W. Alps, a relatively continuous, 15 km long fragment of oceanic lithosphere exhumed from ~80 km depths), which preserve evidence of intraslab fluid flow and eclogitic, intermediate-depth seismicity of Mw ~4. We finally address how, in the long-term and at subduction scale, the overall fluid content and fluid regime may control the slicing, size and metastability of exhumed units. We propose that mechanical coupling varies through time, from weak to strong, as a function of the contrast of effective viscosity on either side of the interface: a young and wet subduction interface will promote the formation of knockers and sole accretion, whereas a fluid-present yet drier and colder one will lead to mainly metasedimentary underplated material and large-scale slivers of (metastable) oceanic lithosphere. This interpretation is supported by bi-phase numerical models (allowing for fluid migration driven by concentrations in the rocks, non-lithostatic pressure gradients and deformation, mantle wedge hydration and mechanical weakening of the plate interface) showing that the detachment of large-scale oceanic tectonic slices is in particular promoted by fluid migration along the subduction interface. [Hacker et al., Journal of Geophysical Research 2003; Audet et al., Nature, 2009; Angiboust et al., Geology 2012

  8. The Interface of Pacific and Other Knowledges in a Supplementary Education Site

    ERIC Educational Resources Information Center

    Fairbairn-Dunlop, Peggy

    2014-01-01

    Because identity (language and culture) are central to Pacific knowledge and knowledge construction processes, Pacific students' educational experiences should be viewed through a cultural lens that sees Pacific knowledge and practices as valid and valued. This study explores the relationship between culture and educational outcomes as seen…

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

    NASA Technical Reports Server (NTRS)

    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 rheological medium to the application of a far-field stress imposed by plate motions. The forward models were used both to gain insight into the range of strain transients to be expected under different assumed mechanical conditions and to develop representations for strain fields that allow GPS, borehole, and other strain data to be combined in a self-consistent, yet well-determined, manner. The models also provided a basis for hypothesis testing, by which data from a strain transient well characterized by GPS and borehole observations were utilized to distinguish among competing candidates for the causative physical mechanism and the governing physical characteristics. During the three years of this project, continued to a fourth year through a no-cost extension of the grant, we published 14 papers and presented or co-authored 37 papers at national scientific meetings.

  10. Unraveling The Complex Interaction Between The Southern Caribbean, Northwest South America And The Pacific Plates During The Cenozoic

    NASA Astrophysics Data System (ADS)

    Villagomez, D.; Spikings, R.

    2013-05-01

    We have studied the prominent Sierra Nevada de Santa Marta Massif (the highest peak in the world whose local base is at sea level, ~5.75km) in Northern Colombia and we are interested in quantifying the thermal and tectonic history of the Northernmost Andes during the Cenozoic in order to understand the complex interaction between the Caribbean, the South American and the Pacific plates. In order to do so, apatite fission track data (by the LA-ICP-MS method) has been used, collected along several traverses and a single vertical profile within the massif. Our results show that the easternmost part of Sierra Nevada de Santa Marta exhumed at elevated rates (?0.2 Km/My) during 65-58 Ma in response to the collision of the Caribbean Plateau with north-western South America. A second pulse of exhumation (?0.32 Km/My) during 50-40 Ma was probably driven by the underthrusting of the Caribbean Plate beneath northern South America. More southern portions of the Sierra Nevada de Santa Marta (the Sierra Nevada Province) exhumed rapidly during 26-29 Ma (~0.7 Km/My), whereas farther north, the northwestermost corner of the Sierra Nevada de Santa Marta (the Santa Marta Province) exhumed at elevated rates during 30-25 Ma and 25-16 Ma. Our thermochronological data show that the highest exhumation rates within the Sierra Nevada de Santa Marta progressed towards the northwest via the propagation of NW-verging thrusts. The late Oligocene-Miocene exhumation was mainly a consequence of compression originating at the Pacific margin of South America that also gave rise to uplift and exhumation in other regions of Eastern Colombia (e.g. in the Santander Massif). Major continental faults such as the left-lateral Santa Marta-Bucaramanga Fault have played an important role transferring the deformation, Exhumation of the Sierra Nevada de Santa Marta Massif is not recorded after ~16 Ma, which is unexpected, given the high elevation and high erosive power of the climate, implying that rock and surface uplift that gave rise to the current topography was probably very recent and there has been insufficient time to expose the fossil apatite partial annealing zone.

  11. Deformation across the Pacific-North America plate boundary near San Francisco, California

    USGS Publications Warehouse

    Prescott, W.H.; Savage, J.C.; Svarc, J.L.; Manaker, D.

    2001-01-01

    We have detected a narrow zone of compression between the Coast Ranges and the Great Valley, and we have estimated slip rates for the San Andreas, Rodgers Creek, and Green Valley faults just north of San Francisco. These results are based on an analysis of campaign and continuous Global Positioning System (GPS) data collected between 1992 and 2000 in central California. The zone of compression between the Coast Ranges and the Great Valley is 25 km wide. The observations clearly show 3.8??1.5 mm yr-1 of shortening over this narrow zone. The strike slip components are best fit by a model with 20.8??1.9 mm yr-1 slip on the San Andreas fault, 10.3??2.6 mm yr-1 on the Rodgers Creek fault, and 8.1??2.1 mm yr-1 on the Green Valley fault. The Pacific-Sierra Nevada-Great Valley motion totals 39.2??3.8 mm yr-1 across a zone that is 120 km wide (at the latitude of San Francisco). Standard deviations are one ??. The geodetic results suggest a higher than geologic rate for the Green Valley fault. The geodetic results also suggest an inconsistency between geologic estimates of the San Andreas rate and seismologic estimates of the depth of locking on the San Andreas fault. The only convergence observed is in the narrow zone along the border between the Great Valley and the Coast Ranges.

  12. Constraints on Late Cretaceous and Cenozoic Extension in the Ross Sea from the Southwest Pacific Plate Circuit

    NASA Astrophysics Data System (ADS)

    Cande, S. C.; Stock, J. M.

    2004-12-01

    Magnetic anomalies and fracture zone trends north of the Ross Sea associated with Australia-Antarctic, Pacific-Antarctic and Lord Howe Rise-Antarctic sea floor spreading place strong constraints on Late Cretaceous and Cenozoic motion between East and West Antarctica. There appear to be two episodes of extension in the Western Ross Sea in this time period. The younger episode, starting about 45 Ma and ending around 25 Ma, is well constrained by differences in spreading rates on the Southeast Indian Ridge (SEIR) on either side of the Balleny FZ and by magnetic anomalies straddling the Adare Trough (Cande et al., 2000). These data document about 150 km of ENE-WSW directed extension across the Adare Basin just north of the Ross Sea. An earlier (80 to 55 Ma) episode of extension is not well constrained in large part because the spreading rate between Australia and East Antarctica was very slow and identifications of magnetic anomalies older than anomaly 24 on the SEIR are problematical. However, there are useful constraints imposed by fitting magnetic anomalies and fracture zone traces from north of the Iselin Bank, from southwest of the Campbell Plateau and from the South Tasman Sea. These features form a network of tectonic constraints that have to be fit by any proposed model of East - West Antarctic motion. A reconstruction of the conjugate splays of the Emerald FZ shows that the Iselin Trough, a fossil rift structure northeast of the Iselin Bank, formed by a local ccw rotation of 12 degrees about 72.6° S, 183° E of the Iselin Bank between anomalies 27 and 24, thus constraining East-West Antarctic extension in this period to the corridor west of the Iselin Bank. These features also enable us to test the plate circuit formed by closing the Campbell Plateau and Challenger Plateau to its pre-rift (50 Ma) configuration and closing the Tasman Sea, SEIR and Pacific-Antarctic ridge. Rotations for the SEIR which treat the older Australia-Antarctic magnetic anomalies as isochrons (Tikku and Cande, 1999) are not appropriate for this test since they produce a large overlap of the South Tasman Rise and Tasmania with Northern Victoria Land. The SEIR rotations of Royer and Rollett (1997), which do not fit the Australia-Antarctic anomalies very well, produce a reasonable closure of the Iselin Bank with Northern Victoria Land and predict about 100 km of additional (pre-55 Ma) extension in the northern Ross Sea.

  13. Extraordinary high ductility/strength of the interface designed bulk W-ZrC alloy plate at relatively low temperature

    NASA Astrophysics Data System (ADS)

    Xie, Z. M.; Liu, R.; Miao, S.; Yang, X. D.; Zhang, T.; Wang, X. P.; Fang, Q. F.; Liu, C. S.; Luo, G. N.; Lian, Y. Y.; Liu, X.

    2015-11-01

    The refractory tungsten alloys with high ductility/strength/plasticity are highly desirable for a wide range of critical applications. Here we report an interface design strategy that achieves 8.5?mm thick W-0.5?wt. %ZrC alloy plates with a flexural strength of 2.5?GPa and a strain of 3% at room temperature (RT) and ductile-to-brittle transition temperature of about 100?°C. The tensile strength is about 991?MPa at RT and 582?MPa at 500?°C, as well as total elongation is about 1.1% at RT and as large as 41% at 500?°C, respectively. In addition, the W-ZrC alloy plate can sustain 3.3?MJ/m2 thermal load without any cracks. This processing route offers the special coherent interfaces of grain/phase boundaries (GB/PBs) and the diminishing O impurity at GBs, which significantly strengthens GB/PBs and thereby enhances the ductility/strength/plasticity of W alloy. The design thought can be used in the future to prepare new alloys with higher ductility/strength.

  14. Extraordinary high ductility/strength of the interface designed bulk W-ZrC alloy plate at relatively low temperature.

    PubMed

    Xie, Z M; Liu, R; Miao, S; Yang, X D; Zhang, T; Wang, X P; Fang, Q F; Liu, C S; Luo, G N; Lian, Y Y; Liu, X

    2015-01-01

    The refractory tungsten alloys with high ductility/strength/plasticity are highly desirable for a wide range of critical applications. Here we report an interface design strategy that achieves 8.5?mm thick W-0.5?wt. %ZrC alloy plates with a flexural strength of 2.5?GPa and a strain of 3% at room temperature (RT) and ductile-to-brittle transition temperature of about 100?°C. The tensile strength is about 991?MPa at RT and 582?MPa at 500?°C, as well as total elongation is about 1.1% at RT and as large as 41% at 500?°C, respectively. In addition, the W-ZrC alloy plate can sustain 3.3?MJ/m(2) thermal load without any cracks. This processing route offers the special coherent interfaces of grain/phase boundaries (GB/PBs) and the diminishing O impurity at GBs, which significantly strengthens GB/PBs and thereby enhances the ductility/strength/plasticity of W alloy. The design thought can be used in the future to prepare new alloys with higher ductility/strength. PMID:26531172

  15. Extraordinary high ductility/strength of the interface designed bulk W-ZrC alloy plate at relatively low temperature

    PubMed Central

    Xie, Z. M.; Liu, R.; Miao, S.; Yang, X. D.; Zhang, T.; Wang, X. P.; Fang, Q. F.; Liu, C. S.; Luo, G. N.; Lian, Y. Y.; Liu, X.

    2015-01-01

    The refractory tungsten alloys with high ductility/strength/plasticity are highly desirable for a wide range of critical applications. Here we report an interface design strategy that achieves 8.5?mm thick W-0.5?wt. %ZrC alloy plates with a flexural strength of 2.5?GPa and a strain of 3% at room temperature (RT) and ductile-to-brittle transition temperature of about 100?°C. The tensile strength is about 991?MPa at RT and 582?MPa at 500?°C, as well as total elongation is about 1.1% at RT and as large as 41% at 500?°C, respectively. In addition, the W-ZrC alloy plate can sustain 3.3?MJ/m2 thermal load without any cracks. This processing route offers the special coherent interfaces of grain/phase boundaries (GB/PBs) and the diminishing O impurity at GBs, which significantly strengthens GB/PBs and thereby enhances the ductility/strength/plasticity of W alloy. The design thought can be used in the future to prepare new alloys with higher ductility/strength. PMID:26531172

  16. Deep Fluids from the Subducting Pacific Plate and Associated Microbial Activity on a Mariana Forearc Serpentine Seamount, ODP Leg 195

    NASA Astrophysics Data System (ADS)

    Mottl, M. J.; Komor, S. C.; Fryer, P.

    2001-12-01

    As the Pacific plate subducts beneath the non-accretionary Mariana forearc its crust emits water and other volatiles that hydrate the mantle of the overriding plate. The resulting serpentinite rises through faults to the seafloor, along with partially altered harzburgite and the excess volatiles, to form a belt of serpentine mud volcanoes in the outer half of the forearc that have cold springs at their summits. This mass flux through the forearc represents one of the earliest returns of subducted material to the oceans. To assess this flux, Ocean Drilling Program Site 1200 was drilled on the summit of one of these mud volcanoes. South Chamorro seamount lies near 14 deg.N, 85 km landward of the Mariana trench and 27 km above the top of the subducting plate. Cold springs at its summit, discovered on Dive 351of the Shinkai-6500 in 1996, are populated by mussels, small tubeworms, whelks, and galatheid crabs. We recovered pore waters from three holes drilled on a transect <10, 20, and 80 m from one of these springs. Composition-depth profiles for these pore waters, to a maximum depth of 71 mbsf, verify that water is upwelling through serpentinite to feed the springs. Like the upwelling water sampled on another serpentine mud volcano, Conical seamount, at ODP Site 780 (Leg 125) near 20 deg.N, the ascending water at Site 1200 has a clear chemical signature of a deep-slab origin. It is highly enriched in a suite of elements that are virtually absent in the partially serpentinized, depleted harzburgite matrix, including (mainly carbonate) alkalinity (60; all units in mmol/kg), Na (610), Na/Cl (1.2), K (19), B (3.2), ammonia (0.22), methane (2), and C2 through C6 hydrocarbons. The fluids have a pH of 12.5, similar to the 12.6 at Conical Seamount. They are highly depleted in Mg, Ca, Sr, and Li, and have low concentrations of Si, Mn, Fe, Ba, and phosphate. They are slightly depleted in chloride (510 vs. 545 in seawater) and enriched in sulfate (by 7% relative to chloride). This chloride depletion is much smaller than that in the deep fluid from Conical Seamount, suggesting that the conduit at Conical is more heavily serpentinized and less reactive, allowing more of the H2O from the deep source to arrive at the seafloor without being lost to serpentinization along the way. Pore water composition-depth profiles reveal that these deep fluids feed an active microbial community within the upper 20 mbsf that is oxidizing light hydrocarbons from the fluid while reducing sulfate. At pH 12.5, this is a true extremophile community. Sulfate reduction is most active at two levels. Microbes within the upper level at 3 mbsf reduce seawater sulfate that diffuses downward against the ascending flow. Those within the lower level at 13 mbsf reduce sulfate that is supplied from the subducting slab by the upwelling fluid. As organic carbon is virtually absent within the depleted harzburgite, the microbes rely on methane and the C2 through C6 thermogenic hydrocarbons for their source of organic carbon, and ammonia for their source of nitrogen. Both are supplied by the upwelling fluid. The microbial community intercepts these nutrients and traps them within the ecosystem, where they can be recycled and continually enriched. This process may explain the enrichment in organic carbon in the uppermost sediment. Iron sulfides, and CaCO3 in the form of aragonite needles and chimneys, are also enriched there, by reaction between the ascending fluid, the microbial community, and the overlying seawater.

  17. New insights into North America-Pacific plate boundary deformation from Lake Tahoe, Salton Sea and Southern Baja California

    E-print Network

    Brothers, Daniel Stephen

    2009-01-01

    to the Pacifi c Plate: Tectonics, v. 8, p. 99-115. Stock,c North America plate tectonics of the Neogene southwesternplate motion partitioning and the transition to seafl oor spreading in the Gulf of California: Tectonics,

  18. Project NEPTUNE: an innovative, powered, fibre-optic cabled deep ocean observatory spanning the Juan de Fuca plate, NE Pacific

    NASA Astrophysics Data System (ADS)

    Barnes, C.; Delaney, J.

    2003-04-01

    NEPTUNE is an innovative facility, a deep-water cabled observatory, that will transform marine science. MARS and VENUS are deep and shallow-water test bed facilities for NEPTUNE located in Monterey Canyon, California and in southern British Columbia, respectively; both were funded in 2002. NEPTUNE will be a network of over 30 subsea observatories covering the 200,000 sq. km Juan de Fuca tectonic plate, Northeast Pacific. It will draw power via two shore stations and receive and exchange data with scientists through 3000 km of submarine fiber-optic cables. Each observatory, and cabled extensions, will host and power many scientific instruments on the surrounding seafloor, in seafloor boreholes and buoyed through the water column. Remotely operated and autonomous vehicles will reside at depth, recharge at observatories, and respond to distant labs. Continuous near-real-time multidisciplinary measurement series will extend over 30 years. Free from the limitations of battery life, ship schedules/ accommodations, bad weather and delayed access to data, scientists will monitor remotely their deep-sea experiments in real time on the Internet, and routinely command instruments to respond to storms, plankton blooms, earthquakes, eruptions, slope slides and other events. Scientists will be able to pose entirely new sets of questions and experiments to understand complex, interacting Earth System processes such as the structure and seismic behavior of the ocean crust; dynamics of hot and cold fluids and gas hydrates in the upper ocean crust and overlying sediments; ocean climate change and its effect on the ocean biota at all depths; and the barely known deep-sea ecosystem dynamics and biodiversity. NEPTUNE is a US/Canada (70/30) partnership to design, test, build and operate the network on behalf of a wide scientific community. The total cost of the project is estimated at about U.S. 250 million from concept to operation. Over U.S. 50 million has already been funded for design, development, and the test beds. NEPTUNE will be among the first of many such cabled ocean observatories. Much is to be gained by being among the scientific and industrial pioneers. The multidisciplinary data archive will be an amazing, expanding resource for scientists and students. The public will share in the research discoveries of one of the last unexplored places on earth through an extensive education/outreach program.

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

    NASA Astrophysics Data System (ADS)

    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 determining the slip-rates on each of the major crustal faults prior to the earthquake, we are able to model the pre-earthquake velocity field for comparison with velocities measured using sites constructed post-earthquake. We then determine how individual site velocities have changed in the 3 years following the earthquake, with implications for the rate at which the lower crust and upper mantle viscously relax through time. We find that the viscosity of the lower crust is at least an order of magnitude higher than that of the uppermost mantle, and hypothesize that this is due to mafic material emplaced at the base of the crust as the spreading center developed beneath the Salton Trough since about 6 Ma. The final study investigates crustal deformation and fault slip rates for faults in the northern Mojave and southern Walker Lane regions of the ECSZ. Previous geodetic studies estimated slip-rates roughly double those inferred via geological dating methods in this region for NW striking strike-slip faults, but significantly smaller than geologic estimates for the Garlock fault. Through construction of a detailed elastic block model, which selects only active fault structures, and applying a new, dense GPS velocity field in this region, we are able to estimate slip-rates for the strike-slip faults in the ECSZ that are much closer to those reported from geology.

  20. Tapping of an Enriched Asthenospheric Layer at the Samoan Islands along Fractures Produced by Deformation of the Pacific Plate near the Tonga Trench

    NASA Astrophysics Data System (ADS)

    Dieu, J. J.; Hawkins, J. W.; Natland, J. H.

    2002-12-01

    Samoan basalts derive from mantle sources having a strong EMII signature (high 87Sr/86Sr, K, Rb, and Ba). Stratigraphy tied with radiometric dates reveal an increase, maximum, and waning of the influence of the EMII mantle component in the combined history of the shield volcanoes of successively younger islands, Upolu, Tutuila, and Ta\\`{ }u. This fluctuation is superimposed on, and independent of, Hawaiian-like shield-building, waning alkalic, and post-caldera alkalic stages of volcanism. It is inconsistent with any regular arrangement of EMII within the structure of a postulated mantle plume. The islands are surface expressions of longer east-trending submarine volcanic ridges or lineaments. These and several older shield lineaments appear in satellite-derived bathymetry as en echelon, straight or slightly curving volcanic ridges, each 100-500 km long. They formed in eastward succession on the Pacific Plate as it rode to the west past the strongly curving transform corner of the nearby Tonga trench. They trend more to the east than nested sigmoidal ridges of the mid-plate Hawaiian Islands, and are not nested. Another lineament ~500 km long is superimposed obliquely over the older Upolu and Tutuila lineaments, which it capped with locally extensive Quaternary-Historic post-erosional eruptives over a distance of >200 km. It closely parallels the transform portion of the trench, and formed along a narrow fracture that propagated along the crest of the arch in the Pacific plate that was produced by lateral bending of the plate into that part of the trench (1). The EMII influence along this lineament is strongest to the west, and all lavas along it are distinct from those of the older underlying lineaments in the Pb isotopes (2). The simplest interpretation of Samoan volcanism is that enriched components are irregularly concentrated in a layer or layers at the top of the asthenosphere that has been tapped along fractures produced by shear coupling acting on the edge of the Pacific lithospheric plate where it moves close to or bends toward the transform portion of the Tonga Trench. (1) Hawkins, JW, and Natland, JH, 1975. Earth Planet. Sci. Lett., 24: 427-439 (2) Hart, S.R., Staudigel, H., Koppers, A.P., Blusztajn, J., Baker, E.., Workman, R., Jackson, M., Hauri, E., Kurz, M., Sims, K., Fornari, D., Saal, A., and Lyons, S., 2000. Geochem. Geophys. Geosyst., 1: Paper 2000GC00108.

  1. Earthquakes along the Ryukyu-Kyushu Arc: Strain segmentation, lateral compression, and the thermomechanical state of the plate interface

    NASA Astrophysics Data System (ADS)

    Kao, Honn; Chen, Wang-Ping

    1991-12-01

    We systematically determined the focal depths and mechanisms of 49 large to moderate-sized earthquakes (mb?5.4) that occurred along the Ryukyu-Kyushu arc since 1963 by inverting the waveforms and amplitudes of P and SH wave trains at teleseismic distances. The results are sufficiently precise to delineate seismogenic structures near the plate interface in detail, revealing features not predicted by plate kinematics. In contrast to previous studies of this arc and those along other subduction zones, shallow seismicity along the plate interface is systematic, showing two distinct layers of activities. The second layer of seismicity is delineated by a few earthquakes that occurred at depths between 50 and 65 km, some 10-20 km directly beneath the seismogenic portion of the interplate thrust zone. These earthquakes indicate lateral compressional strain within the subducted slab as their P axes are subparallel to the local strike of the arc, not perpendicular to the arc as one would expect from the direction of plate convergence. The occurrence of these events cannot be accounted for by membrane stress due to the geometry of the subducted slab. To our knowledge, similar earthquakes occurred only beneath the northern Indoburman ranges and along the Banda arc where subducted slabs, as part of the Indian plate, are being dragged northward with their northern edges bumping into east-west trending collision zones nearby. By drawing an analogy between the tectonic settings of these three regions, we interpret events beneath the plate interface along the Ryukyu-Kyushu arc as a consequence of ongoing collision between the Philippine Sea plate and Eurasia near Taiwan. The interplate thrust zone is largely aseismic down to a depth of approximately 30 km. A large number of earthquakes showing low-angle thrust faulting commence at this depth and are accompanied by two events that show antithetic thrust faulting at a slightly shallower depth of 20-25 km. These observations suggest that the strength of the plate interface increases significantly below the depth of proximately 25±5 km. Based upon available heat flow measurements between the trench axis and the volcanic arc, we estimated the temperature field and magnitude of shear traction along the interplate thrust zone, the deepest interplate earthquakes (˜40-50 km) correspond to temperatures of approximately 730-980°C, comparable to the limiting temperature of intraplate mantle earthquakes (˜800°C) and that of intermediate- and deep-focus earthquakes at Wadati-Benioff zones (potential temperature ˜900°K). Therefore, the cessation of seismicity in general is probably controlled by similar temperature conditions regardless of the tectonic settings of source regions. The magnitude of shear traction along the seismogenic portion (˜40-50 km depth) of the interplate thrust zone seems to be of the order of 100 MPa which, in turn, implies a low average coefficient of friction of only 0.10±0.05, considerably less than those observed for laboratory specimens. The inception of intermediate-focus earthquakes within the subducted slab is at a depth of about 100 km. Whereas shallow earthquakes show no apparent variations along the entire arc, intermediate-depth earthquakes indicate downdip extension along the northern end of the arc near Kyushu but abruptly change to downdip compression along the rest of the arc. All available evidence indicates that this is a spatial pattern unrelated to earthquake cycles. At the moment, tectonic interpretation of such a distinct strain segmentation along the arc is enigmatic. Without the presence of clear discontinuities in the age of the subducted slab, the sudden switch in the strain field of the slab is difficult to explain by the continuously varying rate of subduction along the arc. In any case, this pattern of strain segmentation requires the presence of a major accommodation structure, such as a tear fault, in the subducted slab near the Tokara channel. Appendix is available with entire article on microfiche. Order from American Geophysical Union,

  2. Nanoscale investigation of the interface situation of plated nickel and thermally formed nickel silicide for silicon solar cell metallization

    NASA Astrophysics Data System (ADS)

    Mondon, A.; Wang, D.; Zuschlag, A.; Bartsch, J.; Glatthaar, M.; Glunz, S. W.

    2014-12-01

    In the context of nickel silicide formation from plated nickel layers for solar cell metallization, there are several open questions regarding contact adhesion and electrical properties. Nanoscale characterization by transmission electron microscopy has been employed to support these investigations. Interfacial oxides and silicide phases were investigated on differently prepared samples by different analytical methods associated with transmission electron microscopy analysis. Processing variations included the pre-treatment of samples before nickel plating, the used plating solution and the thermal budget for the nickel-silicon solid-state reaction. It was shown that interface oxides of only few nm thickness on both silicon and nickel silicide are present on the samples, depending on the chosen process sequence, which have been shown to play an important role in adhesion of nickel on silicide in an earlier publication. From sample pretreatment variations, conclusions about the role of an interfacial oxide in silicide formation and its influence on phase formation were drawn. Such an oxide layer hinders silicide formation except for pinhole sites. This reduces the availability of Ni and causes a silicide with low Ni content to form. Without an interfacial oxide a continuous nickel silicide of greater depth, polycrystalline modification and expected phase according to thermal budget is formed. Information about the nature of silicide growth on typical solar cell surfaces could be obtained from silicide phase and geometric observations, which were supported by FIB tomography. The theory of isotropic NiSi growth and orientation dependent NiSi2 growth was derived. By this, a very well performing low-cost metallization for silicon solar cells has been brought an important step closer to industrial introduction.

  3. Life and death of the resurrection plate: Evidence for its existence and subduction in the northeastern Pacific in Paleocene-Eocene time

    USGS Publications Warehouse

    Haeussler, P.J.; Bradley, D.C.; Wells, R.E.; Miller, M.L.

    2003-01-01

    Onshore evidence suggests that a plate is missing from published reconstructions of the northeastern Pacific Ooean in Paleocene- Eocene time. The Resurrection plate, named for the Resurrection Peninsula ophiolite near Seward, Alaska, was located east of the Kula plate and north of the Farallon plate. We interpret coeval near-trench magmatism in southern Alaska and the Cascadia margin as evidence for two slab windows associated with trench-ridge-trench (TRT) triple junctions, which formed the western and southern boundaries of the Resurrection plate. In Alaska, the Sanak-Baranof belt of near-trench intrusions records a west-to-east migration, from 61 to 50 Ma, of the northern TRT triple junction along a 2100-km-long section of coastline. In Oregon, Washington, and southern Vancouver Island, voluminous basaltic volcanism of the Siletz River Volcanics, Crescent Formation, and Metchosin Volcanics occurred between ca. 66 and 48 Ma. Lack of a clear age progression of magmatism along the Cascadia margin suggests that this southern triple junction did not migrate significantly. Synchronous near-trench magmatism from southeastern Alaska to Puget Sound at ca. 50 Ma documents the middle Eocene subduction of a spreading center, the crest of which was subparallel to the margin. We interpret this ca. 50 Ma event as recording the subduction-zone consumption of the last of the Resurrection plate. The existence and subsequent subduction of the Resurrection plate explains (1) northward terrane transport along the southeastern Alaska-British Columbia margin between 70 and 50 Ma, synchronous with an eastward-migrating triple junction in southern Alaska; (2) rapid uplift and voluminous magmatism in the Coast Mountains of British Columbia prior to 50 Ma related to subduction of buoyant, young oceanic crust of the Resurrection plate; (3) cessation of Coast Mountains magmatism at ca. 50 Ma due to cessation of subduction, (4) primitive mafic magmatism in the Coast Mountains and Cascade Range just after 50 Ma, related to slab-window magmatism, (5) birth of the Queen Charlotte transform margin at ca. 50 Ma, (6) extensional exhumation of high-grade metamorphic terranes and development of core complexes in British Columbia, Idaho, and Washington, and extensional collapse of the Cordilleran foreland fold-and-thrust belt in Alberta, Montana, and Idaho after 50 Ma related to initiation of the transform margin, (7) enigmatic 53-45 Ma magmatism associated with extension from Montana to the Yukon Territory as related to slab breakup and the formation of a slab window, (8) right-lateral margin-parallel strike-slip faulting in southern and western Alaska during Late Cretaceous and Paleocene time, which cannot be explained by Farallon convergence vectors, and (9) simultaneous changes in Pacific-Farallon and Pacific-Kula plate motions concurrent with demise of the Kula-Resurrection Ridge.

  4. Final amalgamation of the Central Asian Orogenic Belt in NE China: Paleo-Asian Ocean closure versus Paleo-Pacific plate subduction - A review of the evidence

    NASA Astrophysics Data System (ADS)

    Wilde, Simon A.

    2015-11-01

    The Central Asian Orogenic Belt (CAOB) evolved through complex closure of the Paleo-Asian Ocean from the Neoproterozoic to the late Phanerozoic. This caused the Chinese cratons to collide with Eurasia and led to the formation of the world's largest Phanerozoic orogenic belt. Ocean closure commenced in the west and was completed in the east near Changchun. Closure of the Paleo-Asian Ocean in NE China was along the Solonker-Xar Moron-Changchun-Yanji suture and this was likely completed in the Late Permian, although associated activity continued into the Triassic. There was an overlap in the latest Permian-Early Triassic between terminal activity associated with Paleo-Asian Ocean closure and the onset of tectonism associated with subduction of the Paleo-Pacific plate. This switch in geodynamic setting occurred at ~ 260-250 Ma, and is reflected by a relaxing of north-south directed compression and the onset of east-west directed processes related to Paleo-Pacific subduction. By the Early Jurassic, events associated with the westward advance of the Paleo-Pacific plate dominated, leading to extensive development of I-type granites as far inland as the Great Xing'an Range. From ~ 140 Ma, the Paleo-Pacific plate retreated eastward, resulting in an extensional setting in the Early Cretaceous, the effects of which were enhanced by regional thinning of the lithosphere, commonly attributed to delamination. Throughout this period, the eastern Asian margin was tectonically complex. The north-south oriented Jiamusi-Khanka(-Bureya) block was rifted away from the eastern margin of the CAOB in the Late Triassic, but was then re-united in the Jurassic by westward-advancing subduction that affected both the western and eastern margins of the block. Accretionary complexes continued to evolve in the Cretaceous along the whole eastern margin of Asia, with final accretion of the Nadanhada Terrane (part of the Sikhote-Alin accretionary terrane) with the CAOB at ~ 130 Ma, followed by the emplacement of S-type granites.

  5. Cascadia tremor located near plate interface constrained by S minus P wave times.

    PubMed

    La Rocca, Mario; Creager, Kenneth C; Galluzzo, Danilo; Malone, Steve; Vidale, John E; Sweet, Justin R; Wech, Aaron G

    2009-01-30

    Nonvolcanic tremor is difficult to locate because it does not produce impulsive phases identifiable across a seismic network. An alternative approach to identifying specific phases is to measure the lag between the S and P waves. We cross-correlate vertical and horizontal seismograms to reveal signals common to both, but with the horizontal delayed with respect to the vertical. This lagged correlation represents the time interval between vertical compressional waves and horizontal shear waves. Measurements of this interval, combined with location techniques, resolve the depth of tremor sources within +/-2 kilometers. For recent Cascadia tremor, the sources locate near or on the subducting slab interface. Strong correlations and steady S-P time differences imply that tremor consists of radiation from repeating sources. PMID:19179527

  6. Earth's Decelerating Tectonic Plates

    SciTech Connect

    Forte, A M; Moucha, R; Rowley, D B; Quere, S; Mitrovica, J X; Simmons, N A; Grand, S P

    2008-08-22

    Space geodetic and oceanic magnetic anomaly constraints on tectonic plate motions are employed to determine a new global map of present-day rates of change of plate velocities. This map shows that Earth's largest plate, the Pacific, is presently decelerating along with several other plates in the Pacific and Indo-Atlantic hemispheres. These plate decelerations contribute to an overall, globally averaged slowdown in tectonic plate speeds. The map of plate decelerations provides new and unique constraints on the dynamics of time-dependent convection in Earth's mantle. We employ a recently developed convection model constrained by seismic, geodynamic and mineral physics data to show that time-dependent changes in mantle buoyancy forces can explain the deceleration of the major plates in the Pacific and Indo-Atlantic hemispheres.

  7. Large-scale right-slip displacement on the East San Francisco Bay Region fault system, California: Implications for location of late Miocene to Pliocene Pacific plate boundary

    USGS Publications Warehouse

    McLaughlin, R.J.; Sliter, W.V.; Sorg, D.H.; Russell, P.C.; Sarna-Wojcicki, A. M.

    1996-01-01

    A belt of northwardly younging Neogene and Quaternary volcanic rocks and hydrothermal vein systems, together with a distinctive Cretaceous terrane of the Franciscan Complex (the Permanente terrane), exhibits about 160 to 170 km of cumulative dextral offset across faults of the East San Francisco Bay Region (ESFBR) fault system. The offset hydrothermal veins and volcanic rocks range in age from .01 Ma at the northwest end to about 17.6 Ma at the southeast end. In the fault block between the San Andreas and ESFBR fault systems, where volcanic rocks are scarce, hydrothermal vein system ages clearly indicate that the northward younging thermal overprint affected these rocks beginning about 18 Ma. The age progression of these volcanic rocks and hydrothermal vein systems is consistent with previously proposed models that relate northward propagation of the San Andreas transform to the opening of an asthenospheric window beneath the North American plate margin in the wake of subducting lithosphere. The similarity in the amount of offset of the Permanente terrane across the ESFBR fault system to that derived by restoring continuity in the northward younging age progression of volcanic rocks and hydrothermal veins suggests a model in which 80-110 km of offset are taken up 8 to 6 Ma on a fault aligned with the Bloomfield-Tolay-Franklin-Concord-Sunol-Calaveras faults. An additional 50-70 km of cumulative slip are taken up ??? 6 Ma by the Rogers Creek-Hayward and Concord-Franklin-Sunol-Calaveras faults. An alternative model in which the Permanente terrane is offset about 80 km by pre-Miocene faults does not adequately restore the distribution of 8-12 Ma volcanic rocks and hydrothermal veins to a single northwardly younging age trend. If 80-110 km of slip was taken up by the ESFBR fault system between 8 and 6 Ma, dextral slip rates were 40-55 mm/yr. Such high rates might occur if the ESFBR fault system rather than the San Andreas fault acted as the transform margin at this time. Major transpression across the boundary between the Pacific and North American plates at about 3 to 5 Ma would have resulted in the transfer of significant slip back to the San Francisco Peninsula segment of the San Andreas fault. Since that time, the ESFBR fault system has continued to slip at rates of 11-14 mm/yr. If this interpretation is valid, the ESFBR fault system was the Pacific-North American plate boundary between 8 and 6 Ma, and this boundary has migrated both eastward and westward with time, in response to changing plate margin geometry and plate motions.

  8. Geochronology and origin of the Pratt-Welker Seamount Chain, Gulf of Alaska: A new pole of rotation for the Pacific Plate

    NASA Astrophysics Data System (ADS)

    Turner, D. L.; Jarrard, R. D.; Forbes, R. B.

    1980-11-01

    40K-40Ar and fission-track dating of four seamounts near the southeast end of the Pratt-Welker seamount chain in the Gulf of Alaska, in conjunction with previously published K-Ar and fission-track ages near the northwest end of the chain, documents the complex origin of this seamount chain. Transitional basalts from the adjacent guyots Hodgkins, Davidson, and Denson are dated as 14.3 to 18.2 m.y. These ages, only slightly younger than the ages of the underlying crust, indicate formation of these three seamounts at or very near a spreading center. In contrast, alkalic series lavas (alkali olivine basalts and trachytes) from Kodiak, Giacomini, Dickins, and Hodgkins fit a systematic linear age progression: 23.9±0.6 m.y., 20.9±0.4 m.y., 4.0±0.2 m.y., and 2.8±0.2 m.y., respectively. Hodgkins has apparently experienced two generically different episodes of volcanism, separated by about 12 m.y. The age progression among dated alkali basalts is consistent with the hot spot hypothesis and suggests that for the last 24 m.y. the Pacific plate has moved northwest at 4.4±0.4 cm/yr with respect to the Pratt-Welker hot spot. This volcanic propagation rate, together with the rates from other parallel Neogene Pacific chains, allows an improved estimate of the pole and rate of rotation of the Pacific plate relative to hot spots: 70°N, 95°W, and 0.88°±0.10°/m.y. We conclude that no significant motion of the Pratt-Welker hot spot with respect to other Pacific hot spots has yet been detected. However, the Pratt-Welker age data may alternatively be explained by either the longitudinal roll or propagating crack hypothesis. New K-Ar ages from Horton guyot, in the Cobb seamount chain, indicate alkalic volcanism 20.7± .0 m.y. ago, consistent with a predicted age of 20 m.y. based on the hot spot hypothesis. Guyot depths from Horton and the dated Pratt-Welker seamounts are consistent with the K-Ar ages and normal subsidence of oceanic crust.

  9. Distribution and mechanism of Neogene to present-day vertical axis rotations, Pacific-Australian Plate Boundary Zone, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Little, Timothy A.; Roberts, Andrew P.

    1997-01-01

    Remarkably little knowledge exists about mechanisms of vertical axis rotation in continental crust. Steeply dipping basement rocks in South Island, New Zealand, provide an opportunity to map the distribution of rotations across the Pacific-Australian plate boundary zone, and to delineate boundaries of rotated blocks in unusual detail. We synthesize new structural data with new and existing paleomagnetic data, with geodetic data, and with patterns of Neogene-Quaternary faulting in the strike-slip Marlborough fault system. For the past 20 m.y., vertical axis rotations have been hinged about two crustal-scale boundaries near the east coast. The NE hinge accommodated ˜50° of early-middle Miocene clockwise rotation, which caused deformation of the eastern ends of the Alpine-Wairau and Clarence strike-slip faults. The SW hinge has accommodated a further 30°-50° of finite clockwise rotation since ˜4 Ma and deflects active fault traces. The locus of rotation has shifted southwestward astride a subduction margin that is lengthening in that direction. Rotating rocks are pinned to the south against a locked collision zone where the continental Chatham Rise impinges against the margin. Slip on inland strike-slip faults is transformed seaward across a zone of fault termination into rigid body rotation of a large continental block that has been thrust eastward over the downgoing subducted slab of the Pacific plate. The rotation mechanism is a "migrating hinge," which resembles a flexed telephone book. Strike-slip faults are translated through a brecciated hinge region that does not coincide with a fixed material line in the rock.

  10. Inception of the eastern California shear zone and evolution of the PacificNorth American plate boundary: From kinematics

    E-print Network

    Liu, Mian

    Click Here for Full Article Inception of the eastern California shear zone and evolution, yet up to 25% of the relative plate motion is now accommodated by the eastern California shear zone and the ECSZ across the Mojave Desert. These results indicate causative relationship between the SAF

  11. [Study on the compositions in the interface of corrosion inhibition membrane/copper plating layer/iron substrate by depth etching and photoelectron spectroscopy].

    PubMed

    Feng, Shao-bin; Shang, Shi-bo; Feng, Li-ting; Liu, Qing; Zhang, Jing-wei; Li, Zong-hui

    2006-01-01

    In order to explore the reason for the weak bond intensity between pyro-phosphate copper plating layer and iron substrate, spectrum technology was adopted. The compositions of various elements in the perpendicular interface were analyzed. The effect of surface roughness in the metal substrate on various elements distribution was discussed. According to etching time, the membrane layer was divided into three portions: surface layer with nitrogen and oxygen content decreasing quickly, mesosphere of basic fixed composition, and mix disturbing layer with substrate element appearing and occupying a half thickness. Through analyzing oxygen content in the mix layer, it was concluded that the oxygen layer in the interface of copper layer/iron substrate was the main cause of influencing the bond intensity between the plating layer and substrate. PMID:16827371

  12. TH-C-19A-09: Quantification of Transmission and Backscatter Factors as a function of Distance to Inhomogeneity Interface for Three Types of Surgical Implant Plates

    SciTech Connect

    Wilson, D; Mills, M; Wang, B

    2014-06-15

    Purpose: Carbon fiber materials have been increasingly used clinically, mainly in orthopedics, as an alternative to metallic implants because of their minimal artifacts on CT and MRI images. This study characterizes the transmission and backscatter property of carbon fiber plates (CarboFix Orthopedics, Herzeliya, Israel) with measurements for radiation therapy applications, and compares them to traditional Stainless Steel (SS) and Titanium (Ti) metal materials. Methods: For the transmission measurements, 1-mm-thick test plate was placed upstream from a plane parallel Markus chamber, separated by various thicknesses of polystyrene plates in 0.5 cm increments between 0 and 5 cm. With this setup, we quantified the radiation transmission as a function of distance to the inhomogeneity interface. The LINAC source to detector distance was maintained at 100 cm and 200 MU was delivered for each measurement. Two 3-cm solid water phantoms were placed at the top and bottom to provide build up. All the measurements were performed for 6 MV and 18 MV photons. The backscatter measurements had the identical setup, except that the test plate was downstream of the chamber from radiation. Results: The carbon fiber plates did not introduce any measureable inhomogeneity effect on the transmission and backscatter factor because of its low atomic number. In contrast, traditional metal implant materials caused up to 15% dose difference at upstream and 25% backscatter at downstream from radiation. Such differences decrease as the distance to the inhomogeneity interface increases and become unmeasurable at distance of 3 cm and 1 cm for upstream and downstream, respectively. Conclusion: A new type of carbon fiber implant plate was evaluated and found to have minimal inhomogeneity effect in MV radiation beams. Patients would benefit from a carbon based implant over metal for radiation therapy due to their minimal backscatter and imaging artifacts.

  13. Kinematic modeling of fault slip rates using new geodetic velocities from a transect across the Pacific-North America plate boundary through the San Bernardino Mountains, California

    NASA Astrophysics Data System (ADS)

    McGill, Sally F.; Spinler, Joshua C.; McGill, John D.; Bennett, Richard A.; Floyd, Michael A.; Fryxell, Joan E.; Funning, Gareth J.

    2015-04-01

    Campaign GPS data collected from 2002 to 2014 result in 41 new site velocities from the San Bernardino Mountains and vicinity. We combined these velocities with 93 continuous GPS velocities and 216 published velocities to obtain a velocity profile across the Pacific-North America plate boundary through the San Bernardino Mountains. We modeled the plate boundary-parallel, horizontal deformation with 5-14 parallel and one obliquely oriented screw dislocations within an elastic half-space. Our rate for the San Bernardino strand of the San Andreas Fault (6.5 ± 3.6 mm/yr) is consistent with recently published latest Quaternary rates at the 95% confidence level and is slower than our rate for the San Jacinto Fault (14.1 ± 2.9 mm/yr). Our modeled rate for all faults of the Eastern California Shear Zone (ECSZ) combined (15.7 ± 2.9 mm/yr) is faster than the summed latest Quaternary rates for these faults, even when an estimate of permanent, off-fault deformation is included. The rate discrepancy is concentrated on faults near the 1992 Landers and 1999 Hector Mine earthquakes; the geodetic and geologic rates agree within uncertainties for other faults within the ECSZ. Coupled with the observation that postearthquake deformation is faster than the pre-1992 deformation, this suggests that the ECSZ geodetic-geologic rate discrepancy is directly related to the timing and location of these earthquakes and is likely the result of viscoelastic deformation in the mantle that varies over the timescale of an earthquake cycle, rather than a redistribution of plate boundary slip at a timescale of multiple earthquake cycles or longer.

  14. Spatially varying upper mantle of eastern China caused by Pacific Plate subduction: constraints from body-wave tomography and SKS wave splitting measurements

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Zheng, T.; Allen, R. M.

    2011-12-01

    How does the subduction system influence the evolution of cratons is an interesting question. Eastern China, located at the eastern margin of the Eurasia plate, records the geodynamic evolution of the continent associated with the ongoing convergence of the Eurasia and (Paleo-) Pacific and Philippine plates during the Late Mesozoic to Cenozoic. Previous multidisciplinary studies, including geophysics, geology and geochemistry, suggest that the evolution of EC in the Late Mesozoic to Cenozoic exhibit significant temporal and spatial changes from north to south and from west to east. Eastern China is therefore an idea natural laboratory to investigate the evolutions of cratons in a subduction system. In this study, we investigate the upper mantle structures and anisotropy beneath eastern China. The tomographic images are reconstructed based on inversion of body-wave travel-times recorded by ~1300 stations from the updated China National Seismic Network and 9 temporary arrays. In the inversion, crustal corrections from an independent dataset were introduced a prior. SKS wave splitting measurements are made using dataset from ~500 new broadband stations. An overview of the upper mantle velocity images and available splitting results reveal strong spatial variations of upper mantle structures and anisotropy in eastern China. (1) The Vp, Vs and VP/VS images all display that the North China Craton and the South China Block have a strong contrast in the wavelength of velocity anomalies. In the North China Craton, smaller-scale and complex low-velocity structures are widespread in the eastern part; while in the South China Block, the broad Yangtze Craton to the west is high velocity while the Cathaysia Block to the east is predominantly low velocity. (2) The splitting observations are characterized by apparent diversity of anisotropy pattern in adjacent tectonic domains. In eastern part, the fast direction pattern is relative simple with majority trending ENE-WSW, while in the western part of eastern China, the fast directions exhibit strong variations in different tectonic domains. Based on these observations, we propose that the evolution of eastern China was dominated by the subduction of the Pacific plate, while the North China Craton and the South China Block have undergone different dynamic processes. References Zhao L., R. M. Allen, T.Y. Zheng, High-resolution body-wave tomography models of the upper mantle beneath eastern China and the adjacent area, in preparation for Geochem. Geophys. Geosyst., 2011.

  15. Compilation of Surface Creep on California Faults and Comparison of WGCEP 2007 Deformation Model to Pacific-North American Plate Motion

    USGS Publications Warehouse

    Wisely, Beth A.; Schmidt, David A.; Weldon, Ray J., II

    2008-01-01

    This Appendix contains 3 sections that 1) documents published observations of surface creep on California faults, 2) constructs line integrals across the WG-07 deformation model to compare to the Pacific ? North America plate motion, and 3) constructs strain tensors of volumes across the WG-07 deformation model to compare to the Pacific ? North America plate motion. Observation of creep on faults is a critical part of our earthquake rupture model because if a fault is observed to creep the moment released as earthquakes is reduced from what would be inferred directly from the fault?s slip rate. There is considerable debate about how representative creep measured at the surface during a short time period is of the whole fault surface through the entire seismic cycle (e.g. Hudnut and Clark, 1989). Observationally, it is clear that the amount of creep varies spatially and temporally on a fault. However, from a practical point of view a single creep rate is associated with a fault section and the reduction in seismic moment generated by the fault is accommodated in seismic hazard models by reducing the surface area that generates earthquakes or by reducing the slip rate that is converted into seismic energy. WG-07 decided to follow the practice of past Working Groups and the National Seismic Hazard Map and used creep rate (where it was judged to be interseismic, see Table P1) to reduce the area of the fault surface that generates seismic events. In addition to following past practice, this decision allowed the Working Group to use a reduction of slip rate as a separate factor to accommodate aftershocks, post seismic slip, possible aseismic permanent deformation along fault zones and other processes that are inferred to affect the entire surface area of a fault, and thus are better modeled as a reduction in slip rate. C-zones are also handled by a reduction in slip rate, because they are inferred to include regions of widely distributed shear that is not completely expressed as earthquakes large enough to model. Because the ratio of the rate of creep relative to the total slip rate is often used to infer the average depth of creep, the ?depth? of creep can be calculated and used to reduce the surface area of a fault that generates earthquakes in our model. This reduction of surface area of rupture is described by an ?aseismicity factor,? assigned to each creeping fault in Appendix A. An aseismicity factor of less than 1 is only assigned to faults that are inferred to creep during the entire interseismic period. A single aseismicity factor was chosen for each section of the fault that creeps by expert opinion from the observations documented here. Uncertainties were not determined for the aseismicity factor, and thus it represents an unmodeled (and difficult to model) source of error. This Appendix simply provides the documentation of known creep, the type and precision of its measurement, and attempts to characterize the creep as interseismic, afterslip, transient or triggered. Parts 2 and 3 of this Appendix compare the WG-07 deformation model and the seismic source model it generates to the strain generated by the Pacific - North American plate motion. The concept is that plate motion generates essentially all of the elastic strain in the vicinity of the plate boundary that can be released as earthquakes. Adding up the slip rates on faults and all others sources of deformation (such as C-zones and distributed ?background? seismicity) should approximately yield the plate motion. This addition is usually accomplished by one of four approaches: 1) line integrals that sum deformation along discrete paths through the deforming zone between the two plates, 2) seismic moment tensors that add up seismic moment of a representative set of earthquakes generated by a crustal volume spanning the plate boundary, 3) strain tensors generated by adding up the strain associated with all of the faults in a crustal volume spanning the plate

  16. SEISMICITY AND VOLCANISM IN THE PACIFIC NORTHWEST: EVIDENCE FOR THE SEGMENTATION OF THE JUAN DE FUCA PLATE.

    USGS Publications Warehouse

    Weaver, Craig S.; Michaelson, Caryl A.

    1985-01-01

    The distributions of earthquakes and late Cenozoic and Quaternary volcanism in Washington and northern Oregon change markedly across two northeast-striking lines, one near Mount Rainier and one near Mount Hood. On the basis of these observations and a comparison with the Nazoa subduction zone, we propose that the Juan de Fuca subduction zone is divided into two segments. Landward of the coastal thrust zone, we suggest the Juan de Fuca plate dips more steeply beneath the southern segment than beneath the northern segment. Refs.

  17. An unrecognized major collision of the Okhotomorsk Block with East Asia during the Late Cretaceous, constraints on the plate reorganization of the Northwest Pacific

    NASA Astrophysics Data System (ADS)

    Yang, Yong-Tai

    2013-11-01

    Interactions at plate boundaries induce stresses that constitute critical controls on the structural evolution of intraplate regions. However, the traditional tectonic model for the East Asian margin during the Mesozoic, invoking successive episodes of paleo-Pacific oceanic subduction, does not provide an adequate context for important Late Cretaceous dynamics across East Asia, including: continental-scale orogenic processes, significant sinistral strike-slip faulting, and several others. The integration of numerous documented field relations requires a new tectonic model, as proposed here. The Okhotomorsk continental block, currently residing below the Okhotsk Sea in Northeast Asia, was located in the interior of the Izanagi Plate before the Late Cretaceous. It moved northwestward with the Izanagi Plate and collided with the South China Block at about 100 Ma. The indentation of the Okhotomorsk Block within East Asia resulted in the formation of a sinistral strike-slip fault system in South China, formation of a dextral strike-slip fault system in North China, and regional northwest-southeast shortening and orogenic uplift in East Asia. Northeast-striking mountain belts over 500 km wide extended from Southeast China to Southwest Japan and South Korea. The peak metamorphism at about 89 Ma of the Sanbagawa high-pressure metamorphic belt in Southwest Japan was probably related to the continental subduction of the Okhotomorsk Block beneath the East Asian margin. Subsequently, the north-northwestward change of motion direction of the Izanagi Plate led to the northward movement of the Okhotomorsk Block along the East Asian margin, forming a significant sinistral continental transform boundary similar to the San Andreas fault system in California. Sanbagawa metamorphic rocks in Southwest Japan were rapidly exhumed through the several-kilometer wide ductile shear zone at the lower crust and upper mantle level. Accretionary complexes successively accumulated along the East Asian margin during the Jurassic-Early Cretaceous were subdivided into narrow and subparallel belts by the upper crustal strike-slip fault system. The departure of the Okhotomorsk Block from the northeast-striking Asian margin resulted in the occurrence of an extensional setting and formation of a wide magmatic belt to the west of the margin. In the Campanian, the block collided with the Siberian margin, in Northeast Asia. At about 77 Ma, a new oceanic subduction occurred to the south of the Okhotomorsk Block, ending its long-distance northward motion. Based on the new tectonic model, the abundant Late Archean to Early Proterozoic detrital zircons in the Cretaceous sandstones in Kamchatka, Southwest Japan, and Taiwan are interpreted to have been sourced from the Okhotomorsk Block basement which possibly formed during the Late Archean and Early Proterozoic. The new model suggests a rapidly northward-moving Okhotomorsk Block at an average speed of 22.5 cm/yr during 89-77 Ma. It is hypothesized that the Okhotomorsk-East Asia collision during 100-89 Ma slowed down the northwestward motion of the Izanagi Plate, while slab pull forces produced from the subducting Izanagi Plate beneath the Siberian margin redirected the plate from northwestward to north-northwestward motion at about 90-89 Ma.

  18. Effect of glacial-interglacial sea-level changes on the displacement and stress field in the forearc and along the plate interface of subduction zones

    NASA Astrophysics Data System (ADS)

    Li, T.; Hampel, A.

    2011-12-01

    Combined seismological, space-geodetic and numerical studies have shown that the seismicity at subduction zones may be modulated by tides and glacier fluctuations on timescales of 1-100 a, because these changes in loads on Earth's surface are able to alter the stress field in the upper plate and along the plate interface. Here we use a two-dimensional finite-element model of a subduction zone to investigate how glacial-interglacial sea-level changes affect the forearc region and the plate interface. The model results show that a sea-level fall by 125 m over 100 ka causes up to 0.7 m of vertical displacement, with the maximum uplift occurring between the trench and the coast. The uplift signal induced by the sea-level fall decreases to zero ~20 km landward of the coastline. A subsequent sea-level rise by 125 m over 20 ka causes subsidence, which is again most pronounced in the submarine part of the forearc. The sea-level changes cause horizontal displacements of up to 0.12 m, which are directed seaward during sea-level fall and landward during sea-level rise. With respect to the stress field, the sea-level changes lead to variations in the vertical stress and the shear stress of up to 1.23 MPa and 0.4 MPa, respectively. The shear stress variations are highest beneath the coast, i.e. in the area where the sea-level changes cause the strongest flexure. The resulting Coulomb stress changes on the plate interface are of the order of 0.2-0.5 MPa and indicate that earthquakes are promoted during sea-level fall and delayed during sea-level rise. Our findings imply that eustatic sea-level changes during glacial-interglacial periods may have induced displacements and stress changes that were large enough to affect the seismic cycle of subduction thrusts.

  19. Late Triassic bimodal igneous rocks in eastern Heilongjiang Province, NE China: Implications for the initiation of subduction of the Paleo-Pacific Plate beneath Eurasia

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Xu, Wen-Liang; Xu, Yi-Gang; Gao, Fu-hong; Ge, Wen-chun

    2015-01-01

    This paper reports new zircon LA-ICP-MS and SIMS U-Pb ages and Hf isotope data, and whole-rock major and trace element data for Late Triassic igneous rocks of eastern Heilongjiang Province, NE China. These data provide new insights into the timing of the initiation of subduction of the Paleo-Pacific Plate beneath the Eurasian continent. The zircon U-Pb age data indicate that a suite of Late Triassic (228-202 Ma) igneous rocks is present within the Songnen-Zhangguangcai Range Massif and within the western margin of the Khanka Massif. The Late Triassic igneous rocks within the Songnen-Zhangguangcai Range Massif consist of basalts, basaltic andesites, gabbro-diabases, and rhyolites, whereas coeval igneous rocks in the western margin of the Khanka Massif consist of hornblende gabbros and syenogranitic porphyries. These Late Triassic rocks constitute a geochemically bimodal igneous rock association that contains mafic rocks enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE), and depleted in heavy rare earth elements (HREE) and high field strength elements (HFSE) such as Nb, Ta, Zr, Hf, and Ti. Zircons from these mafic rocks have ?Hf (t) values and TDM1 ages of +2.8 to +9.8 and 477-733 Ma, respectively, suggesting that they formed from a primary magma generated by the partial melting of depleted lithospheric mantle material that had been previously modified by subduction-related fluids. The coeval felsic rocks are characterized by enrichments in LREEs and LILEs, and depletions in HREEs and HFSEs (including Nb, Ta, and Ti), and their zircons have ?Hf (t) values and TDM2 ages of +0.6 to +7.9 and 766 to 1461 Ma, respectively, implying that these rocks were generated during the partial melting of juvenile crustal material. The Late Triassic bimodal igneous rocks in eastern Heilongjiang Province, combined with the regional geologic information, therefore record a post-orogenic extensional environment related to the final late Permian-Early Triassic closure of the Paleo-Asian Ocean. In addition, the presence of Late Triassic bimodal igneous rocks within the eastern margin of the Eurasian continent suggests that the subduction of the Paleo-Pacific Plate beneath the Eurasian continent began after the Late Triassic.

  20. A mega shear zone in the Central Range of Taiwan and it's implication for the Late Mesozoic subduction of the paleo-Pacific plate

    NASA Astrophysics Data System (ADS)

    Yi, D. C.; Lin, C. W.

    2012-04-01

    The metamorphic basement "Tananao Complex" exposed in the eastern flank of the Central Range of Taiwan. The ancient Asian continental margin deposited a thick sequence of sandstone, shale, limestone and volcanic rocks that was the protolith of Tananao Complex. In Late Mesozoic Era, the thick sequence of rocks was subjected to several phases of metamorphism and deformation to form the pair metamorphic belts which were the western Tailuko Belt and the eastern Yuli Belt. The Tailuko belt is composed of phyllite, quartzite, quartz-mica schist, meta-conglomerate, gneiss, meta-basite, amphibolite, serpentinite, marble and meta-chert, etc. The Yuli belt is composed of a monotonous assemblage of quartz-mica schist, subordinate meta-basite and serpentinite, etc. It is believed that the boundary of the Tailuko belt and the Yuli belt is a large fault, but the field evidence of the fault has never been found. In this study, meso-scale field investigation of the lithologies and rock fabrics indicate that a mega shear zone, called "The Daguan shear zone", separated the Tailuko belt from the Yuli belt. The Daguan shear zone is a NNE trending and west dipping mega shear zone which is mainly composed of mylonitic dark gray quartz-mica schist and mica schist, intercalated with 1 to 2 centimeters thick of elongated meta-conglomerate band. The shear zone is composed of numerous meso-scale ductile shear zones. Additionally, the shaer zone is characterized by abundant varied quartz veins that have been refolded to lenticular or pod shape and nearly parallel to S2 cleavage. Compaed to the existing geological information of the Central Range, we believe that the Daguan shear zone played a role as the boundary of the subduction zone which the paleo-Pacific Plate subducted into the Eurasian Plate in Late Mesozoic Era.

  1. On gravity from SST, geoid from Seasat, and plate age and fracture zones in the Pacific. [Satellite-to-Satellite Tracking

    NASA Technical Reports Server (NTRS)

    Marsh, B. D.; Marsh, J. G.; Williamson, R. G.

    1984-01-01

    Data from an additional 50 satellite-to-satellite tracking (SST) passes were combined with earlier measurements of the high degree and order (n, m, 12) gravity in the central Pacific. A composite map was produced which shows good agreement with conventional GEM models. Data from the Seasat altimeter was reduced and found to agree well with both the SST and the GEM fields. The maps are dominated especially in the east, by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Further comparison with regional bathymetric data shows a remarkably close correlation with plate age. Each anomaly band is framed by those major fracture zones having large offsets. The regular spacing of these fractures seems to account for the fabric in the gravity fields. Other anomalies are accounted for by hot spots. The source of part of these anomalies is in the lithosphere itself. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantle without complete thermal equilibration is considered. Previously announced in STAR as N84-11559

  2. Geochemistry of primitive lavas of the Central Kamchatka Depression: Magma generation at the edge of the Pacific Plate

    NASA Astrophysics Data System (ADS)

    Portnyagin, Maxim; Bindeman, Ilya; Hoernle, Kaj; Hauff, Folkmar

    New and published major and trace element and isotope (O, Sr, Nd) compositions of the Late Quaternary rocks from the Central Kamchatka Depression (CKD) are used to demonstrate systematic changes in magma genesis along the northern segment of the Kamchatka Arc, above and north of the subducting Pacific slab edge. We envision a number of possible petrologic scenarios for magma generation beneath the CKD and formulate quantitative mass-balance models which lead to three major conclusions departing significantly from previous interpretations of the CKD rocks. First, this study demonstrates that eclogite melts contribute to the composition of virtually all CKD lavas and could be the major agent transferring material from the subducted slab to the mantle wedge, including fluid-mobile elements (e.g., K, Ba). Second, thermal state of the mantle wedge beneath the CKD has primary control on the major composition of primitive magmas, favoring production of low temperature andesitic and dacitic mantle melts toward the slab edge. Third, hydrous slab-fluids might not be required to generate CKD magmatism. Instead, strong enrichment in LILE, high ?18O and 87Sr/86Sr, in some CKD magmas could originate from assimilation of hydrothermally-altered mafic lithosphere. Several concurring factors could facilitate partial melting of the subducting slab beneath the all CKD volcanoes and favor variable modification of the eclogite melts during interaction with the mantle wedge. Large input from slab melting makes CKD magmatism unique in Kamchatka and may contribute to the CKD volcanoes being the most productive arc volcanoes on Earth.

  3. Neotectonic studies of northern Baja California, Mexico, with LANDSAT thematic mapper and SPOT panchromatic imagery: Partitioning of dextral and extensional strain at the Pacific-North America plate boundary

    NASA Technical Reports Server (NTRS)

    Miller, M. Meghan; Crippen, Robert E.; Dixon, Timothy H.

    1991-01-01

    Numerous studies of active faulting in southern California indicate that the San Jacinto, Elsinore, and adjacent faults west of the San Andreas fault accommodate a significant proportion of Pacific-North America relative plate motion. Because of the complex distribution of slip, little is known about the activities of these and similar structures in northern Baja California and the southward transition to the oceanic ridge transform-fault system in the Gulf of California. SPOT and LANDSAT Thematic Mapper imagery for northern Baja California was processed to optimize discrimination of lithologic and structural features. This data was used to suggest a preliminary kinematic framework for distribution of relative plate motion between 31 and 33 degrees north, in which continental borderland tectonics play an important role in partitioning of plate motion.

  4. Dynamic instability of a thin circular plate with friction interface and its application to disc brake squeal

    NASA Astrophysics Data System (ADS)

    Kang, Jaeyoung; Krousgrill, Charles M.; Sadeghi, Farshid

    2008-09-01

    The mathematical formulation for determining the dynamic instability due to transverse doublet modes in the self-excited vibration of a thin annular plate is presented in this paper. An analytical approach is developed to obtain the stability results from the eigenvalue problem of a stationary disc with a finite contact area. The approach uses the eigenfunctions of transverse doublet modes in classical plate theory and establishes the formulation of modal instability due to the modal-interaction of a doublet mode pair. The one-doublet mode model of a disc and a discrete model equivalent to the one-doublet mode model are proposed for providing a more fundamental understanding of the onset of squeal. The analytical models are validated through a comparison of results from a modal expansion model obtained from finite element component models. Throughout the analytical investigation, the pad arc length is found to be a critical design parameter in controlling squeal propensity.

  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

    NASA Astrophysics Data System (ADS)

    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 which the system, initially shallow during Cretaceous (phase 1), would have greatly subsided during Eocene-Oligocene, giving birth to the NCT, as the renewal of the Australia-Pacific convergent plate boundary took place. This renewal of convergence at 45 Ma would have driven the lithosphere of the system to thicken (uplift), leading to a root instability and to its detachment in the mantle (subsidence). Superposed on these two main phases, some local effects, controlled by the geometry of the plate boundary, also appear. Particularly, latest late Eocene local deformation of the Northern NCB is documented, synchronously with the New Caledonian obduction. This asymmetrical deformation which lasted less than a few million years led to the uplift of the Fairway Ridge and the subsidence of the Eastern margin of the basin along NC’s western coast (10 km vertical amplitude). We suggest that as the oceanic crust of the South Loyalty Basin was being obducted onto the Norfolk Ridge at 37 Ma, the NCB subsided under the effect of the overloading and underthrusted to accommodate the compressional deformation as a foreland flexural basin.

  6. A new regime of slab-mantle coupling at the plate interface and its possible implications for the distribution of volcanoes

    NASA Astrophysics Data System (ADS)

    Morishige, Manabu

    2015-10-01

    We investigate the effects of a thin, low viscosity layer just above the subducting slab on 3D thermal and flow structure in the mantle wedge by taking Northeast Japan as an example. The low viscosity layer assumed here is needed to explain the observed low surface heat flow and low seismic attenuation in the forearc by decoupling the mantle from the subducting slab. We find that when the viscosity in the low viscosity layer is sufficiently low, along-arc component of the flow arises inside the layer and produces along-arc temperature variation. It can also be considered as the along-arc changes in the degree of slab-mantle coupling at the plate interface. The onset time and the characteristic wavelength of the 3D flow depend on the viscosity and the extent of the low viscosity layer. In order to explain the observed spatial and temporal changes in the distribution of Quaternary volcanoes in Northeast Japan, the viscosity and the thickness of the low viscosity layer need to be < 5 ×1018 Pas and ˜6 km, respectively. The model proposed here is based on an assumption which is simpler and better constrained by observations compared to previous models. Therefore, it could be an alternative explanation of the distribution of volcanoes in Northeast Japan.

  7. Channel plate for DNA sequencing

    DOEpatents

    Douthart, R.J.; Crowell, S.L.

    1998-01-13

    This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface. 15 figs.

  8. Channel plate for DNA sequencing

    DOEpatents

    Douthart, Richard J. (Richland, WA); Crowell, Shannon L. (Eltopia, WA)

    1998-01-01

    This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface.

  9. Recent plate motions and crustal deformation

    SciTech Connect

    Lisowski, M. )

    1991-01-01

    Reports by U.S. workers on geodetic measurements of recent plate motions or crustal deformation published in 1987-1990 are reviewed. The review begins with global plate motions, proceeds through plate boundaries in California, Alaska, and the Pacific Northwest, and finishes with volcanic phenomena, monument stability and longevity, and GPS relative position measurements. 184 refs.

  10. Is the Pacific splitting in two? 26 January 2008

    E-print Network

    Clouard, Valerie

    to this feat. The world's biggest tectonic plate under the Pacific seems to be tearing apart, forming a new mid the middle of tectonic plates that don't need to be weakened first. Island chains like the Hawaiian, the team built a model of the strain patterns across the Pacific plate using data from the ocean trenches

  11. Assessing Why Plates Move

    NASA Astrophysics Data System (ADS)

    Bowin, C.

    2004-05-01

    Over the past 42 years, since the first realization that the ocean floors are youthful (not ancient relics from early in the history of the Earth), and the concomitant development of the Theory of Plate Tectonics, an understanding of the observed motions has been sought. Speculation and analyses have concentrated upon three principal forces: ridge push, subducted slab pull, and sub-lithosphere traction from Earth's internal convection motions, with forces due to subducted slabs dominating. Some researchers have speculated that the motions of plates are random, however, the author in 1974 noting that a pattern of spreading between Australia and Antarctica progressed in time westward across the Indian Ocean, and then continued opening the Gulf of Aden and on into the Red Sea concluded that plate motions were not random. Recent evidence from the broad exposure of upper mantle rocks (peridotite) on the ocean floor at the ultra slow spreading Gakkel Ridge in the Arctic Ocean, indicate to the author that there is no ridge push force. Thus, seafloor-spreading sites are reactive features, not driving force contributors. A reconstruction of past absolute plate motions shows that sites of subduction have remained near their same arc/trench locations, but spreading centers and transform faults have moved about. Hence, confirming that sites of subduction are an important control for plate motions. The author's analysis of the positive residual geoid anomalies (spherical harmonic degrees 4-10) over arc/trench systems of the world, suggested forces of 2.8x1020-3.2x1021 N are available to drive plate tectonics. Some studies have proposed models for how such forces might couple to plate motions, but none have yet been definitive. New clues are being sought from the unique change in absolute plate motion of the Pacific plate, at about 46-48 Ma ago: from a northward subduction beneath the Aleutian trench/arc during the time when the Emperor seamount chain was formed, to its' present north of west motion subducting beneath the western Pacific trench/arcs, the direction during which the Hawaiian volcanic trend has been formed. Only the Pacific plate shows such a major change in absolute plate motion at that time, and the author takes this change, in but a few million years, to indicate that masses linked to slab subduction are more important than traction from an underlying mantle convection.

  12. Influence of elastomeric seal plate surface chemistry on interface integrity in biofouling-prone systems: Evaluation of a hydrophobic "easy-release" silicone-epoxy coating for maintaining water seal integrity of a sliding neoprene/steel interface

    NASA Astrophysics Data System (ADS)

    Andolina, Vincent L.

    The scientific hypothesis of this work is that modulation of the properties of hard materials to exhibit abrasion-reducing and low-energy surfaces will extend the functional lifetimes of elastomeric seals pressed against them in abrasive underwater systems. The initial motivation of this work was to correct a problem noted in the leaking of seals at major hydropower generating facilities subject to fouling by abrasive zebra mussel shells and extensive corrosion. Similar biofouling-influenced problems can develop at seals in medical devices and appliances from regulators in anesthetic machines and SCUBA diving oxygen supply units to autoclave door seals, injection syringe gaskets, medical pumps, drug delivery components, and feeding devices, as well as in food handling equipment like pasteurizers and transfer lines. Maritime and many other heavy industrial seal interfaces could also benefit from this coating system. Little prior work has been done to elucidate the relationship of seal plate surface properties to the friction and wear of elastomeric seals during sliding contacts of these articulating materials, or to examine the secondary influence of mineralized debris within the contacting interfaces. This investigation utilized the seal materials relevant to the hydropower application---neoprene elastomer against carbon steel---with and without the application of a silicone-epoxy coating (WearlonRTM 2020.98) selected for its wear-resistance, hydrophobicity, and "easy-release" capabilities against biological fouling debris present in actual field use. Analytical techniques applied to these materials before and after wear-producing processes included comprehensive Contact Angle measurements for Critical Surface Tension (CA-CST) determination, Scanning Electron Microscopic inspections, together with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-Ray Fluorescence (XRF) measurements for determination of surface texture and inorganic composition, Multiple Attenuated Internal Reflection (MAIR-IR) and Microscopic Infrared Spectroscopy for organic surface compositional details, light microscopy for wear area quantification, and profilometry for surface roughness estimation and wear depth quantification. Pin-on-disc dynamic Coefficient of Friction (CoF) measurements provided data relevant to forecasts of seal integrity in dry, wet and biofouling-influenced sliding contact. Actual wear of neoprene seal material against uncoated and coated steel surfaces, wet and dry, was monitored after both rotary and linear cyclic wear testing, demonstrating significant reductions in elastomer wear areas and depths (and resultant volumes) when the coating was present. Coating the steel eliminated a 270% increase in neoprene surface area wear and an 11-fold increase in seal abrasive volume loss associated with underwater rusting in rotary experiments. Linear testing results confirm coating efficacy by reducing wear area in both loading regimes by about half. No coating delamination was observed, apparently due to a differential distribution of silicone and epoxy ingredients at the air-exposed vs. steel-bonded interfaces demonstrated by IR and EDS methods. Frictional testing revealed higher Coefficients of Friction (CoF) associated with the low-speed sliding of Neoprene over coated rather than uncoated steel surfaces in a wet environment, indicating better potential seal adhesion between the hydrophobic elastomer and coating than between the elastomer and intrinsically hydrophilic uncoated steel. When zebra mussel biofouling debris was present in the articulating joints, CoF was reduced as a result of a water channel path produced between the articulating surfaces by the retained biological matter. Easier release of the biofouling from the low-CST coated surfaces restored the seal integrity more rapidly with further water rinsing. Rapid sliding diminished these biofouling-related differences, but revealed a significant advantage in reducing the CoF of the elastomer-on-coating couples to less than 50% of the elastomer-on-steel coupl

  13. Seismic tomography constraints on reconstructing the Philippine Sea Plate and its margin 

    E-print Network

    Handayani, Lina

    2005-02-17

    The Philippine Sea Plate has been surrounded by subduction zones throughout Cenozoic time due to the convergence of the Eurasian, Pacific and Indian-Australian plates. Existing Philippine Sea Plate reconstructions have ...

  14. Refined Views of Strike-slip Fault Zones, Seismicity, and State of Stress Associated With the Pacific-North America Plate Boundary in Southern California

    NASA Astrophysics Data System (ADS)

    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 the focal mechanism-derived SHmax is almost bimodal, trending almost north along the San Andreas system, and to the north-northeast on either side. The transition zones from one state of stress to the other is sharp, following a trend from Yucca Valley to Imperial Valley to the east, and the western edge of the Peninsular Ranges to the west. Other local scale heterogeneities in the SHmax trend include NNW trends along the San Andreas fault near Cajon Pass, Tejon Pass, and the Cucapah Range. The regional variations in the SHmax trends are very similar to the pattern of GPS-measured maximum shortening axes of the surface strain rate tensor field, although the GPS strain field tends to be smoother and appears also to reflect some of the deformation in the upper mantle.

  15. California takes earthquakes very seriously. The state straddles two major tectonic plates and is subject to relatively frequent, often major, potentially devastating quakes.

    E-print Network

    California takes earthquakes very seriously. The state straddles two major tectonic plates the Pacific and North American tectonic plates. The Pacific Plate includes a sliver of California and Baja California, as well as Hawaii and most of the Pacific Ocean, while the North American Plate includes

  16. Early Cretaceous arc volcanic suite in Cebu Island, Central Philippines and its implications on paleo-Pacific plate subduction: Constraints from geochemistry, zircon U-Pb geochronology and Lu-Hf isotopes

    NASA Astrophysics Data System (ADS)

    Deng, Jianghong; Yang, Xiaoyong; Zhang, Zhao-Feng; Santosh, M.

    2015-08-01

    The Philippine island arc system is a collage of amalgamated terranes of oceanic, continental and island arc affinities. Here we investigate a volcanic suite in Cebu Island of central Philippines, including basalt, diabase dike, basaltic pyroclastic rock and porphyritic andesite. LA-ICP-MS U-Pb geochronology of zircon grains from the porphyritic andesite and pyroclastic rock yielded ages of 126 ± 3 Ma and 119 ± 2 Ma, respectively, indicating an Early Cretaceous age. The age distribution of the detrital zircons from river sand in the area displays a peak at ca. 118 Ma, close to the age of the pyroclastic rock. The early Cretaceous volcanic rocks in the central Philippines were previously regarded as parts of ophiolite complexes by most investigators, whereas the Cebu volcanics are distinct from these, and display calc-alkaline affinity and island arc setting, characterized by high LREE/HREE ratios and low HFSE contents. These features are similar to the Early Cretaceous arc basalts in the Amami Plateau and east Halmahera in the northernmost and southernmost West Philippine Basin respectively. Zircon Hf isotopes of the pyroclastic rocks show depleted nature similar to those of the Amami Plateau basalts, implying the subducted Pacific-type MORB as probable source. Zircon Hf isotopes of the porphyritic andesite show slight enrichment relative to that of the pyroclastic rocks and MORB, indicating subducted sediments as a minor end-member in the source. The Hf isotopic compositions of the volcanic rocks are also reflected in the detrital zircons from the river sands. We propose that the volcanic rocks of Cebu Island were derived from partial melting of sub-arc mantle wedge which was metasomatized by dehydration of subducted oceanic crust together with minor pelagic sediments. Within the tectonic environment of Southeast Asia during Early Cretaceous, the volcanic rocks in Cebu Island can be correlated to the subduction of paleo-Pacific plate. The Early Cretaceous volcanic suites in Cebu Island along with the Early Cretaceous arc volcanic rocks, ophiolites and boninites in the southern-western-northern margin of West Philippine Basin are inferred to have formed within single subduction zone before the opening of the Philippine Sea Plate.

  17. Accretion and Subduction of Oceanic Lithosphere: 2D and 3D Seismic Studies of Off-Axis Magma Lenses at East Pacific Rise 9°37-40'N Area and Downgoing Juan de Fuca Plate at Cascadia Subduction Zone

    NASA Astrophysics Data System (ADS)

    Han, Shuoshuo

    Two thirds of the Earth's lithosphere is covered by the ocean. The oceanic lithosphere is formed at mid-ocean ridges, evolves and interacts with the overlying ocean for millions of years, and is eventually consumed at subduction zones. In this thesis, I use 2D and 3D multichannel seismic (MCS) data to investigate the accretionary and hydrothermal process on the ridge flank of the fast-spreading East Pacific Rise (EPR) at 9°37-40'N and the structure of the downgoing Juan de Fuca plate at the Cascadia subduction zone offshore Oregon and Washington. Using 3D multichannel seismic (MCS) data, I image a series of off-axis magma lenses (OAML) in the middle or lower crust, 2-10 km from the ridge axis at EPR 9°37-40'N. The large OAMLs are associated with Moho travel time anomalies and local volcanic edifices above them, indicating off-axis magmatism contributes to crustal accretion though both intrusion and eruption (Chapter 1). To assess the effect of OAMLs on the upper crustal structure, I conduct 2-D travel time tomography on downward continued MCS data along two across-axis lines above a prominent OAML in our study area. I find higher upper crustal velocity in a region ~ 2 km wide above this OAML compared with the surrounding crust. I attribute these local anomalies to enhanced precipitation of alteration minerals in the pore space of upper crust associated with high-temperature off-axis hydrothermal circulation driven by the OAML (Chapter 2). At Cascadia, a young and hot end-member of the global subduction system, the state of hydration of the downgoing Juan de Fuca (JdF) plate is important to a number of subduction processes, yet is poorly known. As local zones of higher porosity and permeability, faults constitute primary conduits for seawater to enter the crust and potentially uppermost mantle. From pre-stack time migrated MCS images, I observe pervasive faulting in the sediment section up to 200 km from the deformation front. Yet faults with large throw and bright fault plane reflections that are developed under subduction bending are confined to a region 50-60 km wide offshore Oregon and less than ~45 km wide offshore Washington. Near the deformation front of Oregon margin, bending-related faults cut through the crust and extend to ~6-7 km in the mantle, whereas at Washington margin, faults are confined to upper and middle crust, indicating that Oregon margin has experienced more extensive bend faulting and related alteration. These observations argue against pervasive serpentinization in the slab mantle beneath Washington and suggest mechanisms other than dehydration embrittlement need to be considered to explain the intermediate depth earthquakes found along the Washington margin (Chapter 3). Using MCS images of a ~400 km along-strike profile ~10-15 km from the deformation front, I investigate the along-trench variation of the structure of downgoing JdF plate and its relation to the regional segmentation of Cascadia subduction zone. I observe that the propagator wakes within the oceanic plate are associated with anomalous basement topography and crustal reflectivity. Further landward, segment boundaries of ETS recurrence interval and relative timing align with the propagator traces within the subducting plate. I propose while the upper plate structure or composition may determine the threshold of fluid pore pressure at which ETS occur, the propagators may define barriers for ETS events that occur at the same time. I also observe a change in crustal structure near 45.8°N that is consistent with an increase in bend-faulting and hydration south of 45.8°N;. In addition, four previously mapped oblique strike-slip faults are associated with changes in Moho reflection, indicating that they transect the entire crust and may cause localized mantle hydration (Chapter 4).

  18. Chemical and isotopic diversity in basalts dredged from the East Pacific Rise at 10°S, the fossil Galapagos Rise and the Nazca plate

    USGS Publications Warehouse

    Batiza, Rodey; Oestrike, Richard; Futa, Kiyoto

    1982-01-01

    The dredges from the East Pacific Rise at about 10°S recovered unusual transitional, light rare-earth element (LREE) enriched basalts which show a range of fractionation. On the basis of their chemical and isotopic abundances, it is unlikely that the lavas are related by a single simple process of magmatic differentiation. We suggest that the mantle source region of these basalts was chemically and isotopically heterogeneous. The chemistry of LREE-depleted tholeiitic basalt dredged from near the axis of the extinct Galapagos Rise indicates complex petrogenesis and differentiation. The presence of tholeiitic basalts here indicates that unlike the Guadalupe and Mathematician fossil ridges, the Galapagos Rise has not been the site of voluminous post-abandonment alkalic volcanism. Alkalic basalts of picritic bulk composition dredged from an elongate seamount near the Galapagos Rise do not represent liquid compositions. Instead, we suggest that these alkalic liquids contain added olivine and plagioclase xenocrysts. Although most of the samples analyzed are very fresh, a few have been altered. The latter exhibit characteristic chemical and isotopic effects of seawater alteration.

  19. The South Pacific superswell

    NASA Astrophysics Data System (ADS)

    McNutt, Marcia K.; Fischer, Karen M.

    Seafloor depths in a broad area of French Polynesia are 250 to 750 m shallower than lithosphere of the same age in the North Pacific and the North Atlantic. The area of shallow seafloor also correlates with a region of high density of volcanoes, low seismic velocity in the upper mantle, and a reduction in the thickness of the elastic plate supporting the volcanoes. The Marquesas fracture zone marks an abrupt transition between normal lithosphere to the north which follows the thermal subsidence curve for a 125-km-thick plate and shallow lithosphere to the south which behaves as though it is only 75-km thick. This age dependence in the French Polynesian depth anomalies, the low elastic plate thickness, and the change in depth at the Marquesas fracture zone, a lithospheric discontinuity, require elevated temperatures in the lithosphere. The pattern and amplitude of the depth anomaly is not consistent with the notion that it results from lithospheric thinning beneath a number of overlapping hot spot swells. Rather, we propose that hot spot traces cluster in this region because the lithosphere is already thinner and more vulnerable to magma penetration. The reduction in the thickness of the thermal plate is presumably due to enhanced small-scale convection resulting from the thermal and/or chemical effect of a broad mantle up welling beneath the South Pacific as imaged by seismic tomography. The morphologic and petrologic characteristics of this superswell resemble those that existed in the mid-Cretaceous over H. W. Menard's Darwin Rise, a region of the Pacific which includes the Mid-Pacific Mountains, the Marshall Islands, Magellan Seamounts, and Wake Guyots. We propose that the South Pacific superswell is the modern-day equivalent of the Darwin Rise, and that it may be merely an extreme example of global variability in lithospheric thermal structure as a function of temperature, chemistry, and/or state-of-stress in the upper mantle.

  20. Tectonics of the Easter plate

    NASA Technical Reports Server (NTRS)

    Engeln, J. F.; Stein, S.

    1984-01-01

    A new model for the Easter plate is presented in which rift propagation has resulted in the formation of a rigid plate between the propagating and dying ridges. The distribution of earthquakes, eleven new focal mechanisms, and existing bathymetric and magnetic data are used to describe the tectonics of this area. Both the Easter-Nazca and Easter-Pacific Euler poles are sufficiently close to the Easter plate to cause rapid changes in rates and directions of motion along the boundaries. The east and west boundaries are propagating and dying ridges; the southwest boundary is a slow-spreading ridge and the northern boundary is a complex zone of convergent and transform motion. The Easter plate may reflect the tectonics of rift propagation on a large scale, where rigid plate tectonics requires boundary reorientation. Simple schematic models to illustrate the general features and processes which occur at plates resulting from large-scale rift propagation are used.

  1. Plating on stainless steel alloys

    SciTech Connect

    Dini, J.W.; Johnson, H.R.

    1981-09-11

    Quantitative adhesion data are presented for a variety of electroplated stainless steel type alloys. Results show that excellent adhesion can be obtained by using a Wood's nickel strike or a sulfamate nickel strike prior to final plating. Specimens plated after Wood's nickel striking failed in the deposit rather than at the interface between the substrate and the coating. Flyer plate quantitative tests showed that use of anodic treatment in sulfuric acid prior to Wood's nickel striking even further improved adhesion. In contrast activation of stainless steels by immersion or cathodic treatment in hydrochloric acid resulted in very reduced bond strengths with failure always occurring at the interface between the coating and substrate.

  2. Cenozoic reconstruction of southwest Pacific

    SciTech Connect

    Chun, Y.Y.; Kroenke, L.W.

    1986-07-01

    Poles of opening and spreading rates for some of the well-studied marginal basins in the southwest Pacific have been redetermined. Times of opening range from Late Cretaceous-Paleocene in the Tasman basin to middle Pliocene in the Bismarck Sea. The observed magnetic lineations in most of these basins show a relatively short duration of opening and relatively small area of total opening. Most of the smaller basins are bounded by troughs and arcuate island chains, some of which are inferred to be trenches and volcanic arcs situated along paleoconvergent boundaries. At least four successive paleoconvergent boundaries are believed to have formed between the Pacific and the Indian-Australian plates during the Cenozoic. Combining the newly determined poles of opening, spreading rates, and paleoplate boundary locations, a series of palinspastic maps of the southwest Pacific have been constructed for these times, relative to a fixed hot-spot frame of reference for both the Pacific and Indian-Australian plates.

  3. Overriding Plate Controls on Subduction Zone Evolution

    NASA Astrophysics Data System (ADS)

    Sharples, W. K.; Jadamec, M. A.; Moresi, L. N.; Capitanio, F. A.

    2014-12-01

    Seismic data, rock deformation experiments, and geochemical studies indicate variability in the thickness, buoyancy, and strength of the lithosphere at plate boundaries. However, geodynamic models of subduction commonly either omit an overriding plate or do not investigate role of the variation in overriding plate properties on the subduction evolution. We present time-dependent numerical models of subduction that vary the overriding plate thickness, strength, and density and allow for a plate interface that evolves with time via an anisotropic brittle failure rheology. We examine the emergence of (a) asymmetric versus symmetric subduction, (b) trench retreat versus advance, (c) subduction zone geometry, (d) slab stagnation versus penetration into the lower mantle, and (e) flat slab subduction. The majority of the models result in sustained asymmetric subduction. The models demonstrate that trench retreat is correlated with a thin overriding plate, whereas, trench advance is correlated with a thick and/or strong overriding plate. Slab dip, measured at a depth below the plate boundary interface, has a negative correlation with an increase in overriding plate thickness. Overriding plate thickness exerts a first order control over slab penetration into the lower mantle, with penetration most commonly occurring in models with a thick overriding plate. Periods of flat slab subduction occur with thick, strong overriding plates producing strong plate boundary interface coupling. The results provide insight into how the overriding plate plays a role in establishing advancing and retreating subduction, as well as providing an explanation for the variation of slab geometry observed in subduction zones on Earth.

  4. Global Plate Velocities from the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Larson, Kristine M.; Freymueller, Jeffrey T.; Philipsen, Steven

    1997-01-01

    We have analyzed 204 days of Global Positioning System (GPS) data from the global GPS network spanning January 1991 through March 1996. On the basis of these GPS coordinate solutions, we have estimated velocities for 38 sites, mostly located on the interiors of the Africa, Antarctica, Australia, Eurasia, Nazca, North America, Pacific, and South America plates. The uncertainties of the horizontal velocity components range from 1.2 to 5.0 mm/yr. With the exception of sites on the Pacific and Nazca plates, the GPS velocities agree with absolute plate model predictions within 95% confidence. For most of the sites in North America, Antarctica, and Eurasia, the agreement is better than 2 mm/yr. We find no persuasive evidence for significant vertical motions (less than 3 standard deviations), except at four sites. Three of these four were sites constrained to geodetic reference frame velocities. The GPS velocities were then used to estimate angular velocities for eight tectonic plates. Absolute angular velocities derived from the GPS data agree with the no net rotation (NNR) NUVEL-1A model within 95% confidence except for the Pacific plate. Our pole of rotation for the Pacific plate lies 11.5 deg west of the NNR NUVEL-1A pole, with an angular speed 10% faster. Our relative angular velocities agree with NUVEL-1A except for some involving the Pacific plate. While our Pacific-North America angular velocity differs significantly from NUVEL-1A, our model and NUVEL-1A predict very small differences in relative motion along the Pacific-North America plate boundary itself. Our Pacific-Australia and Pacific- Eurasia angular velocities are significantly faster than NUVEL-1A, predicting more rapid convergence at these two plate boundaries. Along the East Pacific Pise, our Pacific-Nazca angular velocity agrees in both rate and azimuth with NUVFL-1A.

  5. Pacific Array

    NASA Astrophysics Data System (ADS)

    Kawakatsu, H.; Takeo, A.; Isse, T.; Nishida, K.; Shiobara, H.; Suetsugu, D.

    2014-12-01

    Based on our recent results on broadband ocean bottom seismometry, we propose a next generation large-scale array experiment in the ocean. Recent advances in ocean bottom broadband seismometry (e.g., Suetsugu & Shiobara, 2014, Annual Review EPS), together with advances in the seismic analysis methodology, have now enabled us to resolve the regional 1-D structure of the entire lithosphere/asthenosphere system, including seismic anisotropy (both radial and azimuthal), with deployments of ~10-15 broadband ocean bottom seismometers (BBOBSs) (namely "ocean-bottom broadband dispersion survey"; Takeo et al., 2013, JGR; Kawakatsu et al., 2013, AGU; Takeo, 2014, Ph.D. Thesis; Takeo et al., 2014, JpGU). Having ~15 BBOBSs as an array unit for 2-year deployment, and repeating such deployments in a leap-frog way (an array of arrays) for a decade or so would enable us to cover a large portion of the Pacific basin. Such efforts, not only by giving regional constraints on the 1-D structure, but also by sharing waveform data for global scale waveform tomography, would drastically increase our knowledge of how plate tectonics works on this planet, as well as how it worked for the past 150 million years. International collaborations might be sought.

  6. The Indosinian collision-extension event between the South China Block and the Palaeo-Pacific plate: Evidence from Indosinian alkaline granitic rocks in Dashuang, eastern Zhejiang, South China

    NASA Astrophysics Data System (ADS)

    Mao, Jianren; Ye, Haimin; Liu, Kai; Li, Zilong; Takahashi, Yutaka; Zhao, Xilin; Kee, Weon-Seo

    2013-07-01

    This study reports on the first comprehensive analysis of the geology, petrology and origin of the Dashuang pluton in Jinhua, eastern Zhejiang, South China, which is predominantly composed of quartz monzonite and subordinate quartz syenite that includes variable amounts of aegirine-augite. The quartz monzonite has a porphyritic texture defined by K-feldspar phenocrysts, whereas the quartz syenite shows considerable variation in grain size and is categorised into fine- and coarse-grained types. Zircons from the quartz monzonite and fine-grained quartz syenite yield LA-MC-ICP-MS (laser ablation-multi-collector-inductively coupled plasma-mass spectrometry) U-Pb ages of 231.60 ± 0.86 Ma and 231.7 ± 1.1 Ma, respectively, indicating crystallisation in the Middle Triassic. The chemistry of the quartz monzonite indicates a calc-alkaline to alkaline evolutionary trend, which may reflect partial melting of upper mantle contaminated by Proterozoic basement rocks, subjected to fractional crystallisation during ascent. Both the fine- and coarse-grained quartz syenites are alkaline and have high rare earth element (REE) concentrations, especially light rare earth elements (LREE), and are relatively enriched in large ion lithosphere elements (LILE). The Al2O3 and NaO2 contents of the quartz syenite increase proportionally with SiO2, owing to greater amounts of aegirine-augite and feldspar. The fine-grained quartz syenite has the lowest initial 87Sr/86Sr ratio and lowest Nd model age, and the highest ?Nd value compared with the quartz monzonite. The quartz syenite compositions are best explained by fractional crystallisation of an enriched mantle-derived alkaline magma. Slight chemical variations result from source heterogeneities, as well as the spatially variable degrees of melting, assimilation, and other factors. Our new age and geochemical data for the alkaline rocks in eastern Zhejiang, considered together with collisional granites from South Korea, support a history of collision and extension between the Palaeo-Pacific plate and the South China Block during the Indosinian. We use these data to refine the geodynamic model for Indosinian multi-plate convergence in South China.

  7. Pacific Lamprey

    USGS Multimedia Gallery

    Pacific Lamprey mouth suckers adhered to the glass at Bonneville Dam fish viewing window. The native Pacific Lamprey uses the fish ladder at Bonneville Dam.  This species plays a significant role in the foodweb and in Tribal

  8. Intermittent plate tectonics?

    PubMed

    Silver, Paul G; Behn, Mark D

    2008-01-01

    Although it is commonly assumed that subduction has operated continuously on Earth without interruption, subduction zones are routinely terminated by ocean closure and supercontinent assembly. Under certain circumstances, this could lead to a dramatic loss of subduction, globally. Closure of a Pacific-type basin, for example, would eliminate most subduction, unless this loss were compensated for by comparable subduction initiation elsewhere. Given the evidence for Pacific-type closure in Earth's past, the absence of a direct mechanism for termination/initiation compensation, and recent data supporting a minimum in subduction flux in the Mesoproterozoic, we hypothesize that dramatic reductions or temporary cessations of subduction have occurred in Earth's history. Such deviations in the continuity of plate tectonics have important consequences for Earth's thermal and continental evolution. PMID:18174440

  9. Constraints on subducting plate strength within the Kermadec trench

    E-print Network

    Billen, Magali I.

    Constraints on subducting plate strength within the Kermadec trench Magali I. Billen Department to the Kermadec trench allow localized estimates of plate strength within the subducting Pacific plate to be made. The transfer function between topography and gravity is estimated for five trench-parallel ship tracks

  10. Seismicity of the Earth 1900-2012 Philippine Sea plate and vicinity

    USGS Publications Warehouse

    Smoczyk, Gregory M.; Hayes, Gavin P.; Hamburger, Michael W.; Benz, Harley M.; Villaseñor, Antonio; Furlong, Kevin P.

    2013-01-01

    The complex tectonics surrounding the Philippine Islands are dominated by the interactions of the Pacific, Sunda, and Eurasia plates with the Philippine Sea plate (PSP). The latter is unique because it is almost exclusively surrounded by zones of plate convergence. At its eastern and southeastern edges, the Pacific plate is subducted beneath the PSP at the Izu-Bonin, Mariana, and Yap trenches. Here, the subduction zone exhibits high rates of seismic activity to depths of over 600 km, though no great earthquakes (M>8.0) have been observed, likely because of weak coupling along the plate interface. In the northeast, the PSP subducts beneath Japan and the eastern margin of the Eurasia plate at the Nankai and Ryukyu trenches, extending westward to Taiwan. The Nankai portion of this subduction zone has hosted some of the largest earthquakes along the margins of the PSP, including a pair of Mw8.1 megathrust events in 1944 and 1946. Along its western margin, the convergence of the PSP and the Sunda plate is responsible for a broad and active plate boundary system extending along both sides of the Philippine Islands chain. The region is characterized by opposite-facing subduction systems on the east and west sides of the islands, and the archipelago is cut by a major transform structure: the Philippine Fault. Subduction of the Philippine Sea plate occurs at the eastern margin of the islands along the Philippine Trench and its northern extension, the East Luzon Trough. On the west side of Luzon, the Sunda Plate subducts eastward along a series of trenches, including the Manila Trench in the north, the smaller Negros Trench in the central Philippines, and the Sulu and Cotabato trenches in the south. Twentieth and early twentyfirst century seismic activity along the boundaries of the Philippine Sea plate has produced seven great (M>8.0) earthquakes and 250 large (M>7) events. Among the most destructive events were the 1923 Kanto, the 1948 Fukui, and the 1995 Kobe, Japan, earthquakes; the 1935 and the 1999 Chi-Chi, Taiwan, earthquakes; and the 1976 M7.6 Moro Gulf and 1990 M7.6 Luzon, Philippines, earthquakes.

  11. Pore Fluid Pressure and State of Stress Above the Plate Interface from Observations in a 3 Kilometer Deep Borehole: IODP Site C0002, Nankai Trough Subduction Zone

    NASA Astrophysics Data System (ADS)

    Tobin, H. J.; Saffer, D. M.; Hirose, T.; Castillo, D. A.; Kitajima, H.; Sone, H.

    2014-12-01

    During IODP Expedition 348 from October 2013 to January 2014, Site C0002 was drilled to more than 3000 meters' depth into the inner accretionary wedge at the Nankai Trough, setting a new depth record for scientific ocean drilling. It is the first hole to access the deep interior of an active convergent margin. Site C0002 is part of the NanTroSEIZE project off the Kii-Kumano region of Japan, designed to shed light on plate boundary fault zone processes near the up-dip edge of seismogenic locking and slip. The zone from 865 - 3056 meters below the sea floor was sampled via logging-while-drilling measurements, continuous sampling of drill cuttings, and limited coring. This interval was composed of lithified middle to late Miocene hemipelagic sediments and turbidites that are markedly deformed and dip steeply. P-wave speeds from sonic logs increase with depth to ~ 1600 meters, but are constant to slightly decreasing with depth from 1600 to 3050 meters. We hypothesize that this change in trend indicates the onset of elevated pore fluid pressure, but structural and lithologic factors may also play a role. We explore several methods for quantitative estimation of sonic-derived fluid pressure conditions in the inner wedge. A borehole leak-off test (LOT) and a series of borehole pressurization and injection tests were also performed, which we synthesize to estimate the least principal stress, or Shmin. Furthermore, downhole pressure while drilling (PWD) measurements recorded during borehole packoff events provide information on the maximum principal stress, SHmax. Taken together, the LOT and PWD observations suggest that the inner wedge at ~ 2000 meters depth is currently in a strike-slip stress regime, despite its position as the hanging wall of a main plate boundary thrust. This may be a transitional stress regime between shallow normal and deep thrust, controlled by depth-dependent magnitude of the tectonic convergence-related principal stress. Our results document for the first time the stress conditions and material properties in the deep interior of the upper plate to the shallow seismogenic zone.

  12. Interface between Education and State Policy: Australia. Asia and the Pacific Programme of Educational Innovation for Development, Education and Polity, No. 2.

    ERIC Educational Resources Information Center

    Hughes, Phillip; And Others

    One of seven studies in the "Education and Polity" series, this document looks at alternative futures and the interface of education with four areas: communication; employment and leisure; state policy; and technology. The studies were commissioned during 1984 and were conducted by interdisciplinary teams: two in Australia, two in India, one in…

  13. Present-day kinematics of the Rivera plate and implications for tectonics in southwestern Mexico

    NASA Technical Reports Server (NTRS)

    Demets, Charles; Stein, Seth

    1990-01-01

    A model for the present-day motion of the Rivera plate relative to the North America, Cocos, and Pacific plates is derived using new data from the Pacific-Rivera rise and Rivera transform fault, together with new estimates of Pacific-Rivera motions. The results are combined with the closure-consistent NUVEL-1 global plate motion model of DeMets et al. (1990) to examine present-day deformation in southwestern Mexico. The analysis addresses several questions raised in previous studies of the Rivera plate. Namely, do plate motion data from the northern East Pacific rise require a distinct Rivera plate? Do plate kinematic data require the subduction of the Rivera plate along the seismically quiescent Acapulco trench? If so, what does the predicted subduction rate imply about the earthquake recurrence interval in the Jalisco region of southwestern Mexico?

  14. No-net-rotation model of current plate velocities incorporating plate motion model NUVEL-1

    NASA Technical Reports Server (NTRS)

    Argus, Donald F.; Gordon, Richard G.

    1991-01-01

    NNR-NUVEL1 is presented which is a model of plate velocities relative to the unique reference frame defined by requiring no-net-rotation of the lithosphere while constraining relative plate velocities to equal those in global plate motion model NUVEL-1 (DeMets et al., 1990). In NNR-NUVEL1, the Pacific plate rotates in a right-handed sense relative to the no-net-rotation reference frame at 0.67 deg/m.y. about 63 deg S, 107 deg E. At Hawaii the Pacific plate moves relative to the no-net-rotation reference frame at 70 mm/yr, which is 25 mm/yr slower than the Pacific plate moves relative to the hotspots. Differences between NNR-NUVEL1 and HS2-NUVEL1 are described. The no-net-rotation reference frame differs significantly from the hotspot reference frame. If the difference between reference frames is caused by motion of the hotspots relative to a mean-mantle reference frame, then hotspots beneath the Pacific plate move with coherent motion towards the east-southeast. Alternatively, the difference between reference frames can show that the uniform drag, no-net-torque reference frame, which is kinematically equivalent to the no-net-rotation reference frame, is based on a dynamically incorrect premise.

  15. Eos, Vol. 92, No. 8, 22 February 2011 Tectonic plates relocked after 2005

    E-print Network

    Brennand, Tracy

    Eos, Vol. 92, No. 8, 22 February 2011 Tectonic plates relocked after 2005 earthquake and support the interpretation that the tectonic plates have been relocked since late 2006. (Geophysical on the boundary of the North Ameri- can plate and the Pacific plate off Miyagi pre- fecture. Earthquakes

  16. Reactivation of an old plate interface as a strike-slip fault in a slip-partitioned system: Median Tectonic Line, SW Japan

    NASA Astrophysics Data System (ADS)

    Sato, Hiroshi; Kato, Naoko; Abe, Susumu; Van Horne, Anne; Takeda, Tetsuya

    2015-03-01

    In models for strain-partitioning at obliquely-convergent plate boundaries, trench-parallel slip occurs on a vertical fault. Trench-parallel slip at the Nankai subduction zone, SW Japan, is mapped along the Median Tectonic Line (MTL) which dips approximately 40°N. To understand its structural context and how the MTL functions in this slip-partitioned system, we collected a set of three seismic profiles in the Kii peninsula south of Osaka, using a multi-scale acquisition strategy that provides increasingly fine resolution. To understand its fault kinematics, we analyzed microseismic activity in two locations on the fault, using source data from Japan's Hi-net monitoring network. Structural details suggest that the MTL functioned as a megathrust during subduction of the Cretaceous Sanbagawa HP metamorphic belt. Its current pattern of microseismicity shows that it behaves as a strike-slip fault with no indication of a vertical fault at or around its surface trace. Thus, trench-parallel slip at the Nankai is now accommodated on an inclined fault plane in an unusual form of partitioning. This system appears to have developed out of a two-phase tectonic history in which a thrust structure that formed under initial-phase compressive stresses has been reactivated as a strike-slip fault under subsequent-phase shear stresses. Its unusual kinematics show that shear failure can occur on an existing non-vertical fault plane at a regional scale in preference to the rupture of a new ideal (vertical) fault plane.

  17. High Stress Consolidation, Ultrasonic, and Permeability Measurements: Constraints on Physical Properties and In Situ Stress along the Costa Rica Subduction Plate Interface

    NASA Astrophysics Data System (ADS)

    Winner, A.; Saffer, D. M.; Valdez, R. D.

    2014-12-01

    Sediment permeability and consolidation behavior are key parameters in governing the drainage state and thus potential for excess pore fluid pressure in subduction zones. Elevated pore pressure, in turn, is one important control on the strength and sliding behavior of faults. Along many subduction margins, evidence of elevated, near-lithostatic, in situ pore pressure comes from high seismic reflectivity, low P-wave velocity (Vp), and high Vp/Vs ratios. This inference is broadly supported by numerical modeling studies that indicate elevated pore pressures are likely given high rates of burial and tectonic loading, combined with the low permeability of marine mudstones. Here, we report on a series of high-stress consolidation experiments on sediment core samples from the incoming Cocos plate obtained as part of Integrated Ocean Drilling Program (IODP) Expedition 344. Our experiments were designed to measure the consolidation behavior, permeability, and P-wave velocity of the incoming sediments over a range of confining stresses from .5 to 90 MPa. We explore a range of paths,including isostatic loading (?1=?2=?3), K0 consolidation, in which the ratio of ?3/?1 is maintained at ~0.6, and the trixial loading paths designed to maintain a near critical-state failure condition. In our tests, load is increased in a series of steps. After equilibration at each step, we conduct constant head permeability tests, and measure P-wave velocities in a "time of flight" mode. Initial results from isostatic loading tests on hemipelagic mudstone samples from 34 mbsf document consolidation and permeability-porosity trends, in which porosity decreases from 69% to 54% as stress in increased from .5 MPa to 15 MPa, and permeability decreases from 8.1 X 10-18 m2 at 1 MPa to 1.1 X 10-19 m2 at 15 MPa. P-wave velocity increases by 486-568 km/s over this effective stress range. Ultimately, data from our experiments will provide a robust basis for quantifying fluid content and pressure from seismic velocity and fault plane reflectivity at this margin, and provide data to parameterize forward models of fluid flow and consolidation.

  18. Average slip rate at the transition zone on the plate interface in the Nankai subduction zone, Japan, estimated from short-term SSE catalog

    NASA Astrophysics Data System (ADS)

    Itaba, S.; Kimura, T.

    2013-12-01

    Short-term slow slip events (S-SSEs) in the Nankai subduction zone, Japan, have been monitored by borehole strainmeters and borehole accelerometers (tiltmeters) mainly. The scale of the S-SSE in this region is small (Mw5-6), and therefore there were two problems in S-SSE identification and estimation of the fault model. (1) There were few observatories that can detect crustal deformation associated with S-SSEs. Therefore, reliability of the estimated fault model was low. (2) The signal associated with the S-SSE is relatively small. Therefore, it was difficult to detect the S-SSE only from strainmeter and tiltmeter. The former problem has become resolvable to some extent by integrating the data of borehole strainmeter, tiltmeter and groundwater (pore pressure) of the National Institute of Advanced Industrial Science and Technology, tiltmeter of the National Research Institute for Earthquake Science and Disaster Prevention and borehole strainmeter of the Japan Meteorological Agency. For the latter, by using horizontal redundant component of a multi-component strainmeter, which consists generally of four horizontal extensometers, it has become possible to extract tectonic deformation efficiently and detect a S-SSE using only strainmeter data. Using the integrated data and newly developed technique, we started to make a catalog of S-SSE in the Nankai subduction zone. For example, in central Mie Prefecture, we detect and estimate fault model of eight S-SSEs from January 2010 to September 2012. According to our estimates, the average slip rate of S-SSE is 2.7 cm/yr. Ishida et al. [2013] estimated the slip rate as 2.6-3.0 cm/yr from deep low-frequency tremors, and this value is consistent with our estimation. Furthermore, the slip deficit rate in this region evaluated by the analysis of GPS data from 2001 to 2004 is 1.0 - 2.6 cm/yr [Kobayashi et al., 2006], and the convergence rate of the Philippine Sea plate in this region is estimated as 5.0 - 7.0 cm/yr. The difference between the slip deficit rate and the convergence rate is 2.4-6.0 cm/yr, and it is comparable to the average slip rate of S-SSE. Consequently, slow earthquakes such as S-SSEs and tremor that we can detect, roughly cover 50-100 % of quasi-static slip in this region.

  19. Plate-induced Miocene extension in southern California

    SciTech Connect

    Stuart, W.D. Univ. of California, Santa Barbara, CA )

    1992-01-01

    Miocene crustal extension in southern California can be explained by the interaction of tectonic plates in relative motion. The Pacific, Juan de Fuca, and Farallon (Guadalupe) plates are represented by flat elastic plates surrounded by an infinite elastic plate, the eastern part of which represents the North America plate. Forcing is by assigned subduction pull, and tractions at all plate boundaries satisfy a viscous constitutive law. Plate bottoms are stress-free. In the first part of the solution plate velocities and boundary tractions are found from static equilibrium. Then principal horizontal stresses and strains in plate interiors caused by tractions and subduction pull are found by a boundary element procedure. Using plate boundary geometry from Stock and Hodges for early- and mid-Miocene times, it is found that the portion of the North America plate margin between the Mendocino and Rivera triple junctions has maximum extensional strain directed westward. This result is generally consistent with directions associated with metamorphic core complex formation in southern California. The model is also consistent with extensional strain and rotation sense of crustal blocks in the vicinity of Los Angeles, as inferred by Luyendyk and others from paleomagnetic data. In the model the greatest extensional strain of the North America plate occurs near the Pacific-North America transform, in the area above the absent Farallon slab. Extension direction varies from northwest to southwest according to plate geometry, subduction pull (Juan de Fuca and Guadalupe), and plate boundary tractions.

  20. 3-D simulation for the tectonic evolution around the Kanto Region of Japan using the kinematic plate subduction model

    NASA Astrophysics Data System (ADS)

    Hashima, A.; Sato, T.; Ito, T.; Miyauchi, T.; Kameo, K.; Yamamoto, S.

    2011-12-01

    In the Kanto region of Japan, we can observe one of the most active crustal deformations on the earth. In the southern part of the Boso peninsula to the south, the uplift rate is estimated to be 5 mm/yr from the height of marine terraces. From geological evidence, the Kanto mountains to the west are considered to uplift at 1mm/yr. In contrast, the center part of the Kanto region is stable or subsiding, covered by the Holocene sediments. The depth of the basement reaches 3 km at the deepest. Vertical deformation in the timescale of 1 Myr is being revealed by the analysis of the recent seismic reflection experiments compared with the heights of the dated sediment layers exposed on land. These crustal deformation occurs 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 due to the buoyancy of the arc crust. At the plate boundaries near the Izu-Bonin arc, large interplate earthquakes occurred at the Sagami trough in 1703 and 1923 (Kanto earthquake) and at the Nankai trough in 1707, 1854 and 1944. To reveal the crustal deformation under these plate-to-plate interactions, we use the 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. Iterating this effect sequentially backward in time, we can reconstruct the past plate boundary geometry and past crustal deformation fields. Using the above model, we estimate the long-term slip-rate distribution due to plate subduction/collision to explain the crustal deformation in Kanto obtained from geological and geomorphological studies. The basic deformation pattern of the basin-forming movement in the Kanto plain and uplifts in the southern Boso peninsula and in the Kanto and Akaishi mountains cannot be explained by the collision restricted to the Izu peninsula only. It is necessary to assume wider collision extended to the neighboring Sagami and Suruga trough, which is consistent to the width of the arc crust of the Izu-Bonin arc. However, the degree of the collision is relatively small in these areas where large interplate earthquake occurs. The effect of temporal change in geometry of the plate interfaces is not so large in the timescale of 1 Myr.

  1. Using GPS, tide gauge and altimetry data to constrain subduction parameters at the Vanuatu plate boundary.

    NASA Astrophysics Data System (ADS)

    Ballu, V.; Bouin, M.; Baillard, C.; Calmant, S.; Pelletier, B.; Crawford, W. C.; Kanas, T.; Garaebiti, E.

    2012-12-01

    The Vanuatu subduction zone, Southwest Pacific, combines several features that makes it a particularly useful place to study seismic cycles. The convergence rate is high - approximately 12 cm/yr - and the seismic cycle relatively short. Measurements of interseismic motions are helped by relatively high vertical rates, the close proximity of some islands to the plate interface and the existence of very shallow seamounts on either side of the plate interface. The Vanuatu archipelago is part of the Pacific Ring of Fire: the Australian plate subducts eastward beneath the North Fiji basin, on the western border of the Pacific Plate. High topographic features on the diving plate may contribute to locking of the plates, which can play a major role in the genesis of destructive earthquakes. GPS network points were installed in the early 1990s and the geodesy network has been densified through the years, enabling us to map interseismic horizontal and vertical deformation rates throughout the archipelago. More recently, 8 continuous GPS stations were installed, along with 3 continuous seafloor pressure gauges very near to the plate interface. We show results from GPS data collected from 1996 to 2011, that we re-processed and combined into the ITRF2008 reference frame, and altimetry and seafloor pressure data from 1999 to 2010. The GPS results show that vertical deformation rates vary both across and along the archipelago. We believe that these variations result from variable distance to the plate limit and variable locking parameters. In some areas, subsidence rates are close to one centimeter per year. In the Torres islands (at the northern end of the archipelago) where villagers face recurrent coastal flooding, we showed that this flooding is due more to ground motion than to rise in the absolute sea level, even though the sea-level rise rates are locally high and the islands uplift over the long term. In the Central area of Vanuatu, we augmented the on-land network with two offshore sites using absolute pressure gauges. The sites - Wusi and Sabine Banks - are installed beneath altimetry satellite tracks, Wusi Bank on the over-riding plate and Sabine Bank on the subducting plate. The difference in the pressure records between the sites shows that Wusi Bank subsides by 11 +/- 3 mm/yr with respect to Sabine Bank. We combined the water depths derived from the pressure measurements with altimetry-derived sea-surface heights to tie these heights to a global reference frame: Wusi Bank subsides and Sabine Bank's vertical motion is near zero. Using a 2D elastic model and a finite-element code, we used the gradient of vertical deformation between the coast and the Wusi Bank site to discriminate between possible locked zone geometries. The best simple approximation is a 25° dipping, 30 km long fully locked zone, indicating that stress is currently accumulating west of Santo, Central Vanuatu. The movement of Wusi Bank is a key factor in constraining the dip and length of the locked zone, demonstrating the importance of offshore geodesy measurements.

  2. 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

    NASA Astrophysics Data System (ADS)

    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 backward in time, we numerically simulated the evolution of the deformation rates in Kanto. The result shows uplifts in the Akaishi and the Kanto ranges ahead of the Izu-Bonin arc and subsidence in the center of the Kanto plane. This result is consistent with the topography, the free-air gravity anomaly and the height of paleo-shorelines in this area.

  3. The Plate Boundary Observatory: Community Focused Web Services

    NASA Astrophysics Data System (ADS)

    Matykiewicz, J.; Anderson, G.; Lee, E.; Hoyt, B.; Hodgkinson, K.; Persson, E.; Wright, J.; Torrez, D.; Jackson, M.

    2006-12-01

    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, PBO will install 852 continuous GPS stations, 103 borehole strainmeter stations, 28 tiltmeters, and five laser strainmeters, as well as manage data for 209 previously existing continuous GPS stations. UNAVCO provides access to data products from these stations, as well as general information about the PBO project, via the PBO web site (http://pboweb.unavco.org). GPS and strainmeter data products can be found using a variety of channels, including map searches, text searches, and station specific data retrieval. In addition, the PBO construction status is available via multiple mapping interfaces, including custom web based map widgets and Google Earth. Additional construction details can be accessed from PBO operational pages and station specific home pages. The current state of health for the PBO network is available with the statistical snap-shot, full map interfaces, tabular web based reports, and automatic data mining and alerts. UNAVCO is currently working to enhance the community access to this information by developing a web service framework for the discovery of data products, interfacing with operational engineers, and exposing data services to third party participants. In addition, UNAVCO, through the PBO project, provides advanced data management and monitoring systems for use by the community in operating geodetic networks in the United States and beyond. We will demonstrate these systems during the AGU meeting, and we welcome inquiries from the community at any time.

  4. Coseismic Slip Distribution of the 2011 off the Pacific Coast of Tohoku Earthquake Deduced from Land and Seafloor Geodesy

    NASA Astrophysics Data System (ADS)

    Iinuma, T.; Kido, M.; Osada, Y.; Inazu, D.; Ohzono, M.; Tsushima, H.; Hino, R.; Ohta, Y.; Suzuki, S.; Fujimoto, H.; Miura, S.; Shinohara, M.

    2011-12-01

    The 2011 off the Pacific coast of Tohoku Earthquake (M9.0) occurred on 11 March 2011 off the Pacific coast of Tohoku district, northeastern Japan, where the Pacific plate is subducting beneath the overriding continental plate. A number of models of the coseismic slip distribution of this earthquake have been already proposed based on seismological, geodetic, and tsunami data. Here, we present comprehensive coseismic slip distribution model based not only on land GPS data but also on seafloor geodetic observations, which are obtained through recent observation cruises. We combined displacements at seafloor sites that are deduced from two different types of seafloor observations with the displacements at land GPS stations. One is the seafloor crustal deformation observation with GPS/Acoustic ranging (GPS/A). Horizontal displacements associated with the 2011 Tohoku earthquake at 2 GPS/A stations are estimated by comparing the station positions deduced from the observations before and after the earthquake. Another type of the seafloor data is seafloor water pressure that is observed by means of ocean bottom pressure gauge (OBP). We analyzed OBP data observed at 2 cabled and 4 self pop-up stations, and estimated vertical displacements due to the main shock. Displacements at 5 GPS/A stations of Japan Coast Guard [Sato et al., 2011, science] are also included to estimate the coseismic slip distribution of the earthquake. Estimated slip distribution of the 2011 Tohoku Earthquake shows following features. 1) The area of large slip ( > 20 m) is about 100 km x 200 km on the plate interface shallower than 30 km in depth. 2) There is no large slip occurred off southern Iwate prefecture on the plate interface throughout shallow to deep. 3) The latitudinal range of the area of large slip almost corresponds to the one of the area of strong interplate coupling zone off Miyagi prefecture. 4) Significant slip is estimated around the rupture area of 1978 M7.4 Miyagi-oki earthquake (40 ~ 50 km in depth). 5) No large slip is estimated on the shallow plate interface off Fukushima prefecture. These features clarify that the coseismic rupture of the 2011 Tohoku Earthquake is concentrated relatively narrow area off Miyagi prefecture and maximum slip is very large as compared to the empirical scaling law between released moment, fault size, and maximum slip of earthquakes on the subducting plate boundary. The results suggest that most slip occurred on the plate interface where continental crust contacts with the subducting oceanic crust. Off Miyagi prefecture, however, is an exceptional region where coseismic slip also has occurred on the plate interface under the continental mantle. The heterogeneity of the mantle wedge might control this slip heterogeneity in the crust-mantle contact zone. With respect to the shallow plate interface, there is no large slip is estimated off Iwate and Fukushima prefecture. Less accumulated strain due to the weak interplate coupling off Iwate prefecture and strain release due to the slow slip events that are detected by the activity of the small repeating earthquakes (e.g. in 2008) might cause it.

  5. High-frequency seismic radiation during Maule earthquake (Chile, 27/02/2010, Mw 8.8) inferred by backprojection of P waves: evidence of activation of two distinct zones at the downdip part of the plate interface

    NASA Astrophysics Data System (ADS)

    Palo, M.; Tilmann, F. J.; Krueger, F.; Ehlert, L.; Lange, D.; Rietbrock, A.; Jenkins, J.; Hicks, S. P.

    2013-12-01

    We back-project the seismic radiation released by Maule earthquake (Chile, 27/02/2010, Mw 8.8) in three frequency bands: 0.4-3 Hz, 1-4 Hz, 2-8 Hz. We measure the coherence of the seismic traces at 557 stations of US array by semblance. Travel times are estimated starting from a 1D global velocity model (ak135) corrected by two terms: a static correction and a dynamic correction. Static corrections are the mean time corrections to the 1D velocity model, and dynamic corrections are finer time shifts depending on the source-receiver path. Both terms are extracted from the time shifts between different receivers of P-phases of 23 high-magnitude calibration aftershocks, most of which have high precision locations based on the temporary deployment following the Maule earthquake (IMAD). The dynamic corrections are extended over a fine source grid by kriging interpolation. This procedure makes the backprojection results independent of the main shock catalog hypocentre and allows coherent imaging to higher frequencies. During the first 20 seconds of the rupture process, the source is stable nearby the nucleation point, which is close to epicentre proposed by Vigny et al (Science, 2011) based on high rate GPS motion. Afterwards, it moves bilaterally, with the northern front moving with an average velocity of ˜3 km/s. Most of the energy is emitted from the northern patch of the bi-lateral rupture (˜70%), with sporadic emissions from the southern patch. The maximum of stacked energy is located about 150 km north-eastwards from the epicenter and a relative maximum appears south of Arauco peninsula. In the dip direction, energy is mostly emitted from the down-dip edge of the co-seismic area, roughly matching the aftershock distribution. Specifically, we find that coherent radiation is emitted from two distinct belts nearly parallel to the trench. The position of these belts is in good agreement with the location of the aftershocks, which also are arranged in two disconnected zones of the subduction interface at different depths, the deeper of which is characterised by a large number of repeating event clusters (Rietbrock, Jenkins et al., this session). Thus, our backprojection analysis in combination with the aftershock distribution demonstrates the existence of a peculiar doubled downdip transition from seismogenic behaviour to stable sliding. We suspect fluids released from the downgoing plate to be the cause of the transitions in frictional behaviour because of (1) the co-location of high Vp/Vs ratios with the deep interface seismicity, (2) systematic decrease of depth of onset of deeper seismicity with younging incoming plate age, (3) patchy occurrence along-strike of deeper seismicity.

  6. A new seismically constrained subduction interface model for Central America

    E-print Network

    Frankel, Kurt L.

    -dimensional model for the subducting plate interface along the Middle America Trench between northern Nicaragua and geodynamic and tectonic development of convergent plate boundaries. 1. Introduction Convergent tectonic likely lies along the plate interface. Below this depth, an envelope above 90% of seismicity approximates

  7. Volcanism in response to plate flexure.

    PubMed

    Hirano, Naoto; Takahashi, Eiichi; Yamamoto, Junji; Abe, Natsue; Ingle, Stephanie P; Kaneoka, Ichiro; Hirata, Takafumi; Kimura, Jun-Ichi; Ishii, Teruaki; Ogawa, Yujiro; Machida, Shiki; Suyehiro, Kiyoshi

    2006-09-01

    Volcanism on Earth is known to occur in three tectonic settings: divergent plate boundaries (such as mid-ocean ridges), convergent plate boundaries (such as island arcs), and hot spots. We report volcanism on the 135 million-year-old Pacific Plate not belonging to any of these categories. Small alkalic volcanoes form from small percent melts and originate in the asthenosphere, as implied by their trace element geochemistry and noble gas isotopic compositions. We propose that these small volcanoes erupt along lithospheric fractures in response to plate flexure during subduction. Minor extents of asthenospheric melting and the volcanoes' tectonic alignment and age progression in the direction opposite to that of plate motion provide evidence for the presence of a small percent melt in the asthenosphere. PMID:16873612

  8. INTRODUCTION Twenty-five main linear volcanic chains exist on the Pacific

    E-print Network

    Clouard, Valerie

    INTRODUCTION Twenty-five main linear volcanic chains exist on the Pacific plate (Fig. 1 the association between a volcanic chain and a fixed hotspot. In this paper we review published radiometric ages of islands and seamounts on the Pacific plate to guide further work. We also reexamine the origins of ages

  9. Extrapolating Oceanic Age Distributions: Lessons from the Pacific Region

    E-print Network

    Extrapolating Oceanic Age Distributions: Lessons from the Pacific Region David B. Rowley Department plate reconstructions. An area equal in size to the Pacific Basin oceanic lithosphere must-mail: rowley@geosci.uchicago.edu) A B S T R A C T Extrapolation of the age distribution of oceanic lithosphere

  10. A Cenozoic diffuse alkaline magmatic province (DAMP) in the southwest Pacific without rift or plume origin

    E-print Network

    Müller, Dietmar

    A Cenozoic diffuse alkaline magmatic province (DAMP) in the southwest Pacific without rift or plume of the Pacific Plate. A key to generating the Cenozoic magmatism is the combination of metasomatized lithosphere. The model may also provide a mechanism for warming south Pacific mantle and resulting Cenozoic alkaline

  11. Northern east Pacific rise: Evolution from 25 m. y. B. P. to the present

    SciTech Connect

    Mammerickx, J.; Klitgord, K.D.

    1982-08-10

    The northeast Pacific topography and magnetic lineations (25 m.y. B.P. to the Present) record the traces of three major spreading reorganizations. Only one spreading center is observed today, but there is evidence for several ephemeral episodes of twin spreading accompanying the evolution from an extensive Pacific-Guadalupe plate boundary to a much shortened Pacific-Cocos and Pacific-Rivera plate boundary. The 25 m.y. B.P. plate reorganization culminated with the formation of the Guadalupe plate, bound by the Murray fracture zone to the north and the Cocos-Nazca spreading ridge to the south. Between 25 and 12.5 m.y. B.P. spreading continued while the plate retained the same general outline. The 12.5--11 m.y. B.P. reorganization resulted in the creation of a much shortened Pacific-Cocos plate boundary located in its early stages over the Mathematician seamounts and a much reduced Cocos-plate. The last reorganization (6.5--3.5 m.y. B.P.) resulted in the abandonment of the Mathematician spreading ridge as a Pacific-Cocos plate boundary in favor of the East Pacific Rise.

  12. 3-D Simulation of Steady Plate Subduction with Tectonic Erosion: Current Crustal Uplift and Free-Air Gravity Anomaly in Northeast Japan

    NASA Astrophysics Data System (ADS)

    Hashimoto, Chihiro; Sato, Toshinori; Matsu'Ura, Mitsuhiro

    2008-04-01

    Free-air gravity anomaly in plate subduction zones, characterized by island-arc high, trench low and outer-rise gentle high, reflects the cumulative effects of long-term crustal uplift and subsidence. In northeast Japan the island-arc high of observed free-air gravity anomaly takes its maximum about the eastern coastline. On the other hand, the current vertical crustal motion estimated from geological and geomorphological observations shows a gentle uplift in the land area and steep subsidence in the sea area with the neutral point near the eastern coastline. Such a discrepancy in spatial patterns between the free-air gravity anomaly and current vertical crustal motion can be ascribed to a change in the mode of crustal uplift and subsidence associated with the initiation of tectonic erosion at the North American-Pacific plate interface. We developed a realistic 3-D simulation model of steady plate subduction with tectonic erosion in northeast Japan on the basis of elastic/viscoelastic dislocation theory. Through numerical simulations with this model we found that simple steady plate subduction brings about the crustal uplift characterized by island-arc high with its maximum about the eastern coastline, while steady plate subduction with tectonic erosion, which is represented by the landward retreat of the plate interface, brings about gentle uplift in the land area and steep subsidence in the sea area with the neutral point near the eastern coastline. Therefore, if we suppose that tectonic erosion started 3 4 million years ago after the long duration of simple steady plate subduction, we can consistently explain both patterns of free-air gravity anomaly and current crustal uplift in northeast Japan.

  13. Relationship between temperatures and fault slips on the upper surface of the subducting Philippine Sea plate beneath the Kanto district, central Japan

    NASA Astrophysics Data System (ADS)

    Yoshioka, Shoichi; Takagi, Rumi; Matsumoto, Takumi

    2015-05-01

    To elucidate the relationship between interplate temperatures and generation mechanisms for megathrust earthquakes and slow slip events (SSEs) in the Kanto district, central Japan, we performed numerical simulations on the thermal state. For this purpose, we newly developed a 2-D box-type thermal convection model that is able to handle the subduction of two oceanic plates: the young oceanic Philippine Sea (PHS) plate subducts following subduction of the old oceanic Pacific (PAC) plate beneath it. To constrain temperatures on the upper surface of the PHS plate, we used high-density Hi-net heat flow data on land. We found that low heat flow in the Kanto district was caused mostly by subduction of the cold PHS plate. To explain the heat flow distribution in the Kanto district in more detail, we needed to incorporate frictional heating at the plate interface on the seaward side of the corner of the mantle wedge, and temperature changes due to surface erosion and sedimentation associated with crustal deformation during the Quaternary on land into the models. The most suitable pore pressure ratio to explain the heat flow data was 0.98. The thermally estimated seismogenic zone corresponded well to the fault planes of the 1923 Taisho Kanto earthquake and the western half of the 1707 Genroku Kanto earthquake. The eastern half of the fault plane of the 1707 Genroku Kanto earthquake could be divided into two areas; the northwestern fault plane corresponded to the thermally estimated seismogenic zone, whereas the relationship between the southeastern fault plane and interplate temperatures was ambiguous. The off-Boso SSEs occurred on the plate interface at temperatures lower than approximately 250 °C, and the slipped region passed through the 150 °C isotherm, corresponding to the clay mineral phase transformation from smectite to illite. This might suggest that the SSEs occurred in relation to a dehydration process.

  14. Late Tectonic history of Beaufort Sea - North Pacific area

    SciTech Connect

    McWhae, J.R.H.

    1985-02-01

    The Kaltag fault (and its northern associated splay, the Rapid fault array) is the sheared suture between the Eurasian-Alaskan plate and the North American plate in the area between the Mackenzie Delta and the Alaskan Border. This condition has been maintained throughout considerable additional phases of faulting and folding from mid-Cretaceous to the present. Previously, the Alaskan plate had been the northwestern nose of the North America plate. The interplate suture was deflected to the north as the Canadian Shield was approached. The Kaltag fault continued northeastward 2000 km seaward of the Sverdrup rim, northwest of the Canadian Arctic Island, and north of Greenland. The driving force was directed from the southwest by the Eurasian plate after its collision in Early Cretaceous (Hauterivian) with the North American plate and the docking of north-moving exotic terranes from the Pacific. During the early Tertiary, perhaps in concert with the accretion of the Okhotsk block to the Asian plate north of Japan, the northern Pacific subduction zone jumped southward to the Aleutian Arc where it has persisted until today. A distance of 800 km separates the stable shelf of the Canadian craton, at the Alberta Foothills thrust belt, from the subduction zone off Vancouver Island. The foreland thrust belt and the accretion of exotic terranes in Mesozoic and Tertiary times extended the continental crust of the North American plate westward to the present active transform margin with the Pacific plate along the Queen Charlotte fault zone.

  15. Three-dimensional dynamic models of subducting plate-overriding plate-upper mantle interaction

    NASA Astrophysics Data System (ADS)

    Meyer, C.; Schellart, W. P.

    2013-02-01

    We present fully dynamic generic three-dimensional laboratory models of progressive subduction with an overriding plate and a weak subduction zone interface. Overriding plate thickness (TOP) is varied systematically (in the range 0-2.5 cm scaling to 0-125 km) to investigate its effect on subduction kinematics and overriding plate deformation. The general pattern of subduction is the same for all models with slab draping on the 670 km discontinuity, comparable slab dip angles, trench retreat, trenchward subducting plate motion, and a concave trench curvature. The narrow slab models only show overriding plate extension. Subduction partitioning (vSP? / (vSP? + vT?)) increases with increasing TOP, where trenchward subducting plate motion (vSP?) increases at the expense of trench retreat (vT?). This results from an increase in trench suction force with increasing TOP, which retards trench retreat. An increase in TOP also corresponds to a decrease in overriding plate extension and curvature because a thicker overriding plate provides more resistance to deform. Overriding plate extension is maximum at a scaled distance of ~200-400 km from the trench, not at the trench, suggesting that basal shear tractions resulting from mantle flow below the overriding plate primarily drive extension rather than deviatoric tensional normal stresses at the subduction zone interface. The force that drives overriding plate extension is 5%-11% of the slab negative buoyancy force. The models show a positive correlation between vT? and overriding plate extension rate, in agreement with observations. The results suggest that slab rollback and associated toroidal mantle flow drive overriding plate extension and backarc basin formation.

  16. Growth Plate Fractures

    MedlinePLUS

    .org Growth Plate Fractures Page ( 1 ) The bones of children and adults share many of the same risks for injury. But because they ... to a unique injury called a growth plate fracture. Growth plates are areas of cartilage located near ...

  17. Tectonic map of the Circum-Pacific region, Pacific basin sheet

    USGS Publications Warehouse

    Scheibner, E.; Moore, G.W.; Drummond, K.J.; Dalziel, Corvalan Q.J.; Moritani, T.; Teraoka, Y.; Sato, T.; Craddock, C.

    2013-01-01

    Circum-Pacific Map Project: The Circum-Pacific Map Project was a cooperative international effort designed to show the relationship of known energy and mineral resources to the major geologic features of the Pacific basin and surrounding continental areas. Available geologic, mineral, and energy-resource data are being complemented by new, project-developed data sets such as magnetic lineations, seafloor mineral deposits, and seafloor sediment. Earth scientists representing some 180 organizations from more than 40 Pacific-region countries are involved in this work. Six overlapping equal-area regional maps at a scale of 1:10,000,000 form the cartographic base for the project: the four Circum-Pacific Quadrants (Northwest, Southwest, Southeast, and Northeast), and the Antarctic and Arctic Sheets. There is also a Pacific Basin Sheet at a scale of 1:17,000,000. The Base Map Series and the Geographic Series (published from 1977 to 1990), the Plate-Tectonic Series (published in 1981 and 1982), the Geodynamic Series (published in 1984 and 1985), and the Geologic Series (published from 1984 to 1989) all include six map sheets. Other thematic map series in preparation include Mineral-Resources, Energy-Resources and Tectonic Maps. Altogether, more than 50 map sheets are planned. The maps were prepared cooperatively by the Circum-Pacific Council for Energy and Mineral Resources and the U.S. Geological Survey and are available from the Branch of Distribution, U. S. Geological Survey, Box 25286, Federal Center, Denver, Colorado 80225, U.S.A. The Circum-Pacific Map Project is organized under six panels of geoscientists representing national earth-science organizations, universities, and natural-resource companies. The six panels correspond to the basic map areas. Current panel chairmen are Tomoyuki Moritani (Northwest Quadrant), R. Wally Johnson (Southwest Quadrant), Ian W.D. Dalziel (Antarctic Region), vacant. (Southeast Quadrant), Kenneth J. Drummond (Northeast Quadrant), and George W. Moore (Arctic Region). Project coordination and final cartography was being carried out through the cooperation of the Office of the Chief Geologist of the U.S. Geological Survey, under the direction of General Chairman, George Gryc of Menlo Park, California. Project headquarters were located at 345 Middlefield Road, MS 952, Menlo Park, California 94025, U.S.A. The framework for the Circum-Pacific Map Project was developed in 1973 by a specially convened group of 12 North American geoscientists meeting in California. The project was officially launched at the First Circum-Pacific Conference on Energy and Mineral Resources, which met in Honolulu, Hawaii, in August 1974. Sponsors of the conference were the AAPG, Pacific Science Association (PSA), and the Coordinating Committee for Offshore Prospecting for Mineral Resources in Offshore Asian Areas (CCOP). The Circum-Pacific Map Project operates as an activity of the Circum-Pacific Council for Energy and Mineral Resources, a nonprofit organization that promotes cooperation among Circum-Pacific countries in the study of energy and mineral resources of the Pacific basin. Founded by Michel T. Halbouty in 1972, the Council also sponsors conferences, topical symposia, workshops and the Earth Science Series books. Tectonic Map Series: The tectonic maps distinguish areas of oceanic and continental crust. Symbols in red mark active plate boundaries, and colored patterns show tectonic units (volcanic or magmatic arcs, arc-trench gaps, and interarc basins) associated with active plate margins. Well-documented inactive plate boundaries are shown by symbols in black. The tectonic development of oceanic crust is shown by episodes of seafloor spreading. These correlate with the rift and drift sequences at passive continental margins and episodes of tectonic activity at active plate margins. The recognized episodes of seafloor spreading seem to reflect major changes in plate kinematics. Oceanic plateaus and other prominences of greater than normal oceanic crustal thickness such as hotspot traces are also shown. Colored a

  18. GEOPHYSICAL RESEARCH LETTERS, VOL. 26, NO. 23, PAGES 3517-3520, DECEMBER 1, 1999 Motion of the South Bismarck Plate, Papua New Guinea

    E-print Network

    Tregoning, Paul

    on the southern side by the Solomon Sea Plate at the New Britain Trench, eastward and northward by the Pacific with the Australian Plate, subduction of the Solomon Sea Plate and a combination of sinistral motion and extensional Plate at the Weitin Fault and the Bismarck Sea Seismic Lineation (BSSL) [Denham, 1969

  19. High-frequency Pn,Sn phases recorded by ocean bottom seismometers on the Cocos plate

    SciTech Connect

    McCreery, C.S.

    1981-05-01

    Data from ocean bottom seismometers located on the Cocos plate indicate that high-frequency Pn,Sn phases are generated by earthquakes along the subducting margin of that plate and are propagated across the plate. The Sn phase appears to be severely attenuated as it approaches the ridge crest. Estimates of Pn velocity are lower than previous extimates for western Pacific paths, which may indicate a relationship between Pn,Sn velocity and lithospheric age. High frequencies found in these phases suggest that Q for Pn,Sn propagation across the Cocos plate is similar to that for the western Pacific.

  20. NE Pacific St. NE Pacific St.

    E-print Network

    Lake W ashington Ship Canal NE Pacific St. NE Pacific St. NE Boat St. 15th Ave NE 15thAveNE UniversityWayNE BrooklynAveNE NE Pacific St. MontlakeBlvdNE MontlakeBlvdNE Pacific Place NE University Burke-Gilman Trail METRO NW A CD D EF F GHI H J RR BB CC EE AA Rotunda Cafe Ocean Sciences Hitchcock

  1. Subduction Drive of Plate Tectonics

    NASA Astrophysics Data System (ADS)

    Hamilton, W. B.

    2003-12-01

    Don Anderson emphasizes that plate tectonics is self-organizing and is driven by subduction, which rights the density inversion generated as oceanic lithosphere forms by cooling of asthenosphere from the top. The following synthesis owes much to many discussions with him. Hinge rollback is the key to kinematics, and, like the rest of actual plate behavior, is incompatible with bottom-up convection drive. Subduction hinges (which are under, not in front of, thin leading parts of arcs and overriding plates) roll back into subducting plates. The Pacific shrinks because bounding hinges roll back into it. Colliding arcs, increasing arc curvatures, back-arc spreading, and advance of small arcs into large plates also require rollback. Forearcs of overriding plates commonly bear basins which preclude shortening of thin plate fronts throughout periods recorded by basin strata (100 Ma for Cretaceous and Paleogene California). This requires subequal rates of advance and rollback, and control of both by subduction. Convergence rate is equal to rates of rollback and advance in many systems but is greater in others. Plate-related circulation probably is closed above 650 km. Despite the popularity of concepts of plumes from, and subduction into, lower mantle, there is no convincing evidence for, and much evidence against, penetration of the 650 in either direction. That barrier not only has a crossing-inhibiting negative Clapeyron slope but also is a compositional boundary between fractionated (not "primitive"), sluggish lower mantle and fertile, mobile upper mantle. Slabs sink more steeply than they dip. Slabs older than about 60 Ma when their subduction began sink to, and lie down on and depress, the 650-km discontinuity, and are overpassed, whereas younger slabs become neutrally buoyant in mid-upper mantle, into which they are mixed as they too are overpassed. Broadside-sinking old slabs push all upper mantle, from base of oceanic lithosphere down to the 650, back under shrinking oceans, forcing rapid Pacific spreading. Slabs suck forward overriding arcs and continental lithosphere, plus most subjacent mantle above the transition zone. Changes in sizes of oceans result primarily from transfer of oceanic lithosphere, so backarcs and expanding oceans spread only slowly. Lithosphere parked in, or displaced from, the transition zone, or mixed into mid-upper mantle, is ultimately recycled, and regional variations in age of that submerged lithosphere may account for some regional contrasts in MORB. Plate motions make no kinematic sense in either the "hotspot" reference frame (HS; the notion of fixed plumes is easily disproved) or the no-net-rotation frame (NNR) In both, for example, many hinges roll forward, impossible with gravity drive. Subduction-drive predictions are fulfilled, and paleomagnetic data are satisfied (as they are not in HS and NNR), in the alternative framework of propulsionless Antarctica fixed relative to sluggish lower mantle. Passive ridges migrate away from Antarctica on all sides, and migration of these and other ridges permits tapping fresh asthenosphere. (HS and NNR tend to fix ridges). Ridge migration and spreading rates accord with subduction drive. All trenches roll back when allowance is made for back-arc spreading and intracontinental deformation. Africa rotates slowly toward subduction systems in the NE, instead of moving rapidly E as in HS and NNR. Stable NW Eurasia is nearly stationary, instead of also moving rapidly, and S and E Eurasian deformation relates to subduction and rollback. The Americas move Pacificward at almost the full spreading rates of passive ridges behind them. Lithosphere has a slow net westward drift. Reference: W.B. Hamilton, An alternative Earth, GSA Today, in press.

  2. Subducting characteristic of the Pacific slab beneath northeast China

    NASA Astrophysics Data System (ADS)

    Jiang, G.; Zhang, G.; Xu, Y.

    2012-12-01

    The volcanoes locating in northeast China are very active. Some researchers consider that the origin of volcanoes is closely related to the subducting western Pacific plate and the upwelling asthenosphere. The thickness and the existing range of the subducted plate are not clear as far although the seismic tomography results obviously show that the Pacific plate exists below the volcano region. Therefore, in this study, we adopted the method combining the teleseismic tomography with travel time forward modeling to further study the velocity structure beneath northeast China, especially the precise model of subducted Pacific plate. Our results show that (1) the average thickness and velocity perturbation of slab is 85 km and 1%, respectively, and the slab has not been thickened compared with the previous result of the Japan Sea; (2) the Pacific plate subducted into the mantle transition zone with a shallow dip angle, and changed horizontally when it touched the bottom of mantle transition zone, and extended westward to Longitude 127°E and then stops over there; (3) the horizontal slab locates right below the volcano region. These above features help people understand the origin of intraplate volcanoes and the geodynamical process better. (a) Tomographic result along 43°N. Red and blue colors represent the high and low velocity anomalies, respectively, and the scale is shown at the right-bottom; The profile line is shown in (b); The black triangles represent the volcanoes locating near the profile; The black solid and dashed lines show the depths of upper and lower boundaries of Pacific plate, respectively. The red dots represent the deep earthquakes around the profile. (b) Location of profile AA' along 43°N. Black triangles denote volcanoes; White squares represent the stations; Blue contours denote the depth of upper boundary of Pacific plate; Black and red dots represent the deep epicenters.

  3. PACIFIC COAST SALMON pacific Coast Salmon

    E-print Network

    181 PACIFIC COAST SALMON UNIT 12 pacific Coast Salmon Unit 12 ROBERT G. KOPE NMFS Northwest Fisheries Science Center Seattle Washington INTRODUCTION Pacific salmon support important commercial and recreational fisheries in Washington, Oregon, and California. Salmon are a vital part of the cul- ture

  4. Simulations of seismic hazard for the Pacific Northwest of the United States from earthquakes associated with the Cascadia subduction zone

    USGS Publications Warehouse

    Petersen, M.D.; Cramer, C.H.; Frankel, A.D.

    2002-01-01

    We investigate the impact of different rupture and attenuation models for the Cascadia subduction zone by simulating seismic hazard models for the Pacific Northwest of the U.S. at 2% probability of exceedance in 50 years. We calculate the sensitivity of hazard (probabilistic ground motions) to the source parameters and the attenuation relations for both intraslab and interface earthquakes and present these in the framework of the standard USGS hazard model that includes crustal earthquakes. Our results indicate that allowing the deep intraslab earthquakes to occur anywhere along the subduction zone increases the peak ground acceleration hazard near Portland, Oregon by about 20%. Alternative attenuation relations for deep earthquakes can result in ground motions that differ by a factor of two. The hazard uncertainty for the plate interface and intraslab earthquakes is analyzed through a Monte-Carlo logic tree approach and indicates a seismic hazard exceeding 1 g (0.2 s spectral acceleration) consistent with the U.S. National Seismic Hazard Maps in western Washington, Oregon, and California and an overall coefficient of variation that ranges from 0.1 to 0.4. Sensitivity studies indicate that the paleoseismic chronology and the magnitude of great plate interface earthquakes contribute significantly to the hazard uncertainty estimates for this region. Paleoseismic data indicate that the mean earthquake recurrence interval for great earthquakes is about 500 years and that it has been 300 years since the last great earthquake. We calculate the probability of such a great earthquake along the Cascadia plate interface to be about 14% when considering a time-dependent model and about 10% when considering a time-independent Poisson model during the next 50-year interval.

  5. Copper Map Plate Detail

    USGS Multimedia Gallery

    A portion of the engraving on the plate used to print points, lines, and text in black ink. Engravings on the plate are left-to-right reversed. This plate was cleaned and treated to improve the visibility of the engraving. The plate was used to print the Washington [D.C.] and vicinity, 1:31,680-sca...

  6. Sputtering and ion plating

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The proceedings of a conference on sputtering and ion plating are presented. Subjects discussed are: (1) concepts and applications of ion plating, (2) sputtering for deposition of solid film lubricants, (3) commercial ion plating equipment, (4) industrial potential for ion plating and sputtering, and (5) fundamentals of RF and DC sputtering.

  7. Origin of the oceanic basalt basement of the Solomon Islands arc and its relationship to the Ontong Java Plateau-insights from Cenozoic plate motion models

    USGS Publications Warehouse

    Wells, R.E.

    1989-01-01

    Cenozoic global plate motion models based on a hotspot reference frame may provide a useful framework for analyzing the tectonic evolution of the Solomon Islands convergent margin. A postulated late Miocene collision of the Ontong Java Plateau (OJP) with a NE-facing arc is consistent with the predicted path of the OJP across the Pacific Basin and its Miocene arrival at the trench. Late-stage igneous activity (65-30 Ma) predicted for the OJP as it rode over the Samoan hotspot occurred in correlative stratigraphic sections on Malaita, the supposed accreted flake of OJP in the Solomon Islands arc. Convergence similar to the present velocities between Australia and the Pacific plates was characteristic of the last 43 million years. Prior to 43 Ma Pacific-Australia plate motions were divergent, seemingly at odds with geologic evidence for early Tertiary convergence, particularly in Papua New Guinea. A postulated South Pacific plate may have existed between Australia and the Pacific plate and would have allowed implied northward subduction along the northeastern Australia plate boundary that lasted into the early Eocene. Subsequent reorganization of plate motions in the middle Eocene correlates with middle Eocene marginal basin formation along ridges oblique to the main plate boundary. Cessation of spreading on the Pacific-South Pacific Ridge and its subsequent subduction beneath Asia followed the change in Pacific plate motion at 43 Ma. A trapped remnant of the extinct, NW-trending ridge may still lie beneath the western Philippine Sea. The terminal deformation, metamorphism and ophiolite obduction in the Eocene orogen of the southwest Pacific also correlates with the major change in Pacific plate motion at 43 Ma and the subsequent compression of the dying Eocene arc against outlying continental and oceanic crustal blocks of the Australian plate. The Solomon Islands oceanic basement may represent juxtaposition of oceanic plateaus of the Australian plate beneath overthrust, dismembered ophiolite derived from adjacent marginal basin crust. ?? 1989.

  8. Diffusion brazing nickel-plated stainless steel

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.; Mitchell, M. J.

    1976-01-01

    To bond parts, sandwich assembly is made up of aluminum core, aluminum face sheet with brazing alloy interface, and nickel plated stainless steel part. Sandwich is placed between bottom and top glide sheet that is placed in stainless steel retort where assembly is bonded at 580 C.

  9. Plate motions and deformations from geologic and geodetic data

    NASA Technical Reports Server (NTRS)

    Jordan, T. H.

    1986-01-01

    A satellite laser ranging experiment conducted by NASA since 1972 has measured the relative motion between the North America and Pacific plates in California. Based on these measurements, the 896-km distance between San Diego and Quincy, California, is shortening at 62 + or - 9 mm/yr. This geodetic estimate is consistent with the rate of motion between the two plates, calculated from geological data to be 53 + or - 3 mm/yr averaged over the past few million years.

  10. How the interior viscosity structure of a terrestrial planet controls plate driving forces and plate tectonics

    NASA Astrophysics Data System (ADS)

    Hoeink, T.; Lenardic, A.; Jellinek, M.; Richards, M. A.

    2011-12-01

    One of the fundamental unresolved problems in Earth and planetary science is the generation of plate tectonics from mantle convection. Important achievements can be made when considering rheological properties in the context of mantle convection dynamics. Among these milestones are (1) a deeper understanding of the balance of forces that drive and resist plate motion and (2) the dynamic generation of narrow plate boundaries (that lead to a piecewise continuous surface velocity distribution). Extending classic plate-tectonic theory we predict a plate driving force due to viscous coupling at the base of the plate from fast flow in the asthenosphere. Flow in the asthenosphere is due to shear-driven contributions from an overriding plate and due to additional pressure-driven contributions. We use scaling analysis to show that the extent to which this additional plate-driving force contributes to plate motions depends on the lateral dimension of plates and on the relative viscosities and thicknesses of lithosphere and asthenosphere. Whereas slab-pull forces always govern the motions of plates with a lateral extent greater than the mantle depth, asthenosphere-drive forces can be relatively more important for smaller (shorter wavelength) plates, large relative asthenosphere viscosities or large asthenosphere thicknesses. Published plate velocities, tomographic images and age-binned mean shear wave velocity anomaly data allow us to estimate the relative contributions of slab-pull and asthenosphere-drive forces driving the motions of the Atlantic and Pacific plates. At the global scale of terrestrial planets, we use 3D spherical shell simulations of mantle convection with temperature-, depth- and stress dependent rheology to demonstrate that a thin low-viscosity layer (asthenosphere) governs convective stresses imparted to the lithosphere. We find, consistent with theoretical predictions, that convective stresses increase for thinner asthenospheres. This result might eliminate the need for special weakening mechanisms to generate plate tectonics from mantle convection. Our results elucidate the role of the asthenosphere for plate tectonics on Earth, and also provide insights into the differences in tectonic styles between Earth and Venus.

  11. On the Origin of Plate Tectonics

    NASA Astrophysics Data System (ADS)

    Bercovici, D.

    2014-12-01

    The emergence of plate tectonics was Earth's defining moment. How and when platetectonics started is shrouded in mystery because of the paucity of observations in theArchean as well the challenge of understanding how plates are generated. The damage theoryof lithospheric weakening by grain-reduction provides a physical framework for plategeneration. This model builds on grain-scale processes to elucidate planetary-scaletectonics, and is consistent with lab and field observations of polycrystalline rocks andlithospheric shear zones. The grain-damage model accounts for the evolution of damage andhealing (by grain growth) at various planetary conditions, hence predicts plate boundaryformation and longevity, and how they depend on surface environment. For example, the onset of prototectonics is predicted to require clement conditions tokeep healing from erasing weak zones; conversely, cool conditions possibly requiredtectonics to draw down primordial CO2. Thus whether tectonics preceded a cool climate (andwater) or vice versa is immaterial as they likely needed each other or neither wouldexist. Sparse evidence that prototectonics co-initiated with liquid water hints at thelink between tectonics, water and surface conditions. The establishment of wide-spread plate tectonics started between >4Ga and 2.7Ga, and mayhave taken over a billion years to develop. Under Earth-like conditions, combininggrain-damage with intermittent Archean protosubduction produces persistent weak zones thataccumulate to yield well developed plates within 1Gyrs. In contrast, Venus' hottersurface conditions promotes healing and prohibits weak zone accumulation, which explainswhy plate tectonics failed to spread on our sister planet. Damage and weak-zone inheritance may also influence plate evolution and reorganization inthe modern era. Changes in plate direction, such as reflected in the Emperor-Hawaiianbend, leave weak zones misaligned with plate motion, causing oblique plate boundaries thatpersist for the age of the plate. Grain-damage within a cold subducting slab may alsocause its very rapid detachment, and the abrupt loss of the slab-pull force could accountfor precipitous changes in plate motion, such as for the Pacific plate at both 47Ma and6Ma.

  12. An updated digital model of plate boundaries

    NASA Astrophysics Data System (ADS)

    Bird, Peter

    2003-03-01

    A global set of present plate boundaries on the Earth is presented in digital form. Most come from sources in the literature. A few boundaries are newly interpreted from topography, volcanism, and/or seismicity, taking into account relative plate velocities from magnetic anomalies, moment tensor solutions, and/or geodesy. In addition to the 14 large plates whose motion was described by the NUVEL-1A poles (Africa, Antarctica, Arabia, Australia, Caribbean, Cocos, Eurasia, India, Juan de Fuca, Nazca, North America, Pacific, Philippine Sea, South America), model PB2002 includes 38 small plates (Okhotsk, Amur, Yangtze, Okinawa, Sunda, Burma, Molucca Sea, Banda Sea, Timor, Birds Head, Maoke, Caroline, Mariana, North Bismarck, Manus, South Bismarck, Solomon Sea, Woodlark, New Hebrides, Conway Reef, Balmoral Reef, Futuna, Niuafo'ou, Tonga, Kermadec, Rivera, Galapagos, Easter, Juan Fernandez, Panama, North Andes, Altiplano, Shetland, Scotia, Sandwich, Aegean Sea, Anatolia, Somalia), for a total of 52 plates. No attempt is made to divide the Alps-Persia-Tibet mountain belt, the Philippine Islands, the Peruvian Andes, the Sierras Pampeanas, or the California-Nevada zone of dextral transtension into plates; instead, they are designated as "orogens" in which this plate model is not expected to be accurate. The cumulative-number/area distribution for this model follows a power law for plates with areas between 0.002 and 1 steradian. Departure from this scaling at the small-plate end suggests that future work is very likely to define more very small plates within the orogens. The model is presented in four digital files: a set of plate boundary segments; a set of plate outlines; a set of outlines of the orogens; and a table of characteristics of each digitization step along plate boundaries, including estimated relative velocity vector and classification into one of 7 types (continental convergence zone, continental transform fault, continental rift, oceanic spreading ridge, oceanic transform fault, oceanic convergent boundary, subduction zone). Total length, mean velocity, and total rate of area production/destruction are computed for each class; the global rate of area production and destruction is 0.108 m2/s, which is higher than in previous models because of the incorporation of back-arc spreading.

  13. Data Access and Web Services at the EarthScope Plate Boundary Observatory

    NASA Astrophysics Data System (ADS)

    Matykiewicz, J.; Anderson, G.; Henderson, D.; Hodgkinson, K.; Hoyt, B.; Lee, E.; Persson, E.; Torrez, D.; Smith, J.; Wright, J.; Jackson, M.

    2007-12-01

    The EarthScope Plate Boundary Observatory (PBO) at UNAVCO, Inc., 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, PBO will install 880 continuous GPS stations, 103 borehole strainmeter stations, and five laser strainmeters, as well as manage data for 209 previously existing continuous GPS stations and one previously existing laser strainmeter. UNAVCO provides access to data products from these stations, as well as general information about the PBO project, via the PBO web site (http://pboweb.unavco.org). GPS and strainmeter data products can be found using a variety of access methods, incuding map searches, text searches, and station specific data retrieval. In addition, the PBO construction status is available via multiple mapping interfaces, including custom web based map widgets and Google Earth. Additional construction details can be accessed from PBO operational pages and station specific home pages. The current state of health for the PBO network is available with the statistical snap-shot, full map interfaces, tabular web based reports, and automatic data mining and alerts. UNAVCO is currently working to enhance the community access to this information by developing a web service framework for the discovery of data products, interfacing with operational engineers, and exposing data services to third party participants. In addition, UNAVCO, through the PBO project, provides advanced data management and monitoring systems for use by the community in operating geodetic networks in the United States and beyond. We will demonstrate these systems during the AGU meeting, and we welcome inquiries from the community at any time.

  14. Circum-Pacific diatomite deposits

    SciTech Connect

    North, F.K.

    1986-07-01

    Deformed diatomites of assured identification are all Oligocene or younger. They are not to be interpreted with oceanic diatom oozes as analogs, nor with California's Monterey Formation as prototype. All examples, apart from the unique Monterey, are deposits of relatively shallow waters at convergent plate or microplate boundaries: in arc-trench gaps or (less importantly) in immediate back-arc belts. Tethyan examples, along a collision boundary, are now slivers in the late stages of external flysch along the fronts of Alpine thrust belts. Circum-Pacific examples, at ocean-continent subduction boundaries, are preserved only on mountainous islands or peninsulas, the uplift (not folding) of which has protected the diatomites and their overlying evaporites from subduction. The control is tectonic and volcanic, not by water temperature or eustatism. Preserved deposits appear to be restricted to particular segments of the Pacific boundary delineated by Benioff zones having some significant minimum dip. The unique Monterey Formation owes its spectacular development and preservation to the conversion of an arc-trench boundary to a transform boundary, at a triple junction, before the diatomite was deposited. The Monterey's importance as an oil source sediment does not stem from its true diatomite component. Other Circum-Pacific diatomites are of negligible significance to the petroleum geologist, but are potentially minable for other uses in Japan, the Philippines, and Peru, and possibly in Chile.

  15. Geodynamics of the Eastern Pacific Region, Caribbean and Scotia Arcs. Volume 9

    SciTech Connect

    Cabre, R.

    1983-01-01

    This book analyze the geodynamic phenomena related to the interaction of the eastern Pacific with the Americas between Canada and the Antarctic peninsula. Studies include the Cordilleran arcs and Juan de Fuca plate.

  16. Environmental materials and interfaces

    SciTech Connect

    Not Available

    1991-11-01

    A workshop that explored materials and interfaces research needs relevant to national environmental concerns was conducted at Pacific Northwest Laboratory. The purposes of the workshop were to refine the scientific research directions being planned for the Materials and Interface Program in the Molecular Science Research Center (MSRC) and further define the research and user equipment to the included as part of the proposed Environmental and Molecular Science Laboratory (EMSL). Three plenary information sessions served to outline the background, objectives, and status of the MSRC and EMSL initiatives; selected specific areas with environmentally related materials; and the status of capabilities and facilities planned for the EMSL. Attention was directed to four areas where materials and interface science can have a significant impact on prevention and remediation of environmental problems: in situ detection and characterization of hazardous wastes (sensors), minimization of hazardous waste (separation membranes, ion exchange materials, catalysts), waste containment (encapsulation and barrier materials), and fundamental understanding of contaminant transport mechanisms. During all other sessions, the participants were divided into three working groups for detailed discussion and the preparation of a written report. The working groups focused on the areas of interface structure and chemistry, materials and interface stability, and materials synthesis. These recommendations and suggestions for needed research will be useful for other researchers in proposing projects and for suggesting collaborative work with MSRC researchers. 1 fig.

  17. Plate tectonics and the Gulf of California region

    SciTech Connect

    Schmidt, N.

    1990-11-01

    The geology and tectonism of California have been influenced greatly by the collision and interaction between the Pacific plate and the North American plate. The forces generated by this interaction caused substantial horizontal movement along the San Andreas fault system and created the Gulf of California rift zone. This article summarizes the unique features of the gulf, describes the theory of plate tectonics, explains how tectonism may have affected the geologic evolution and physiography of the gulf, and illustrates the process by which the Colorado River became linked to the gulf.

  18. MyPlate

    MedlinePLUS

    ... a Budget Create a Grocery Game Plan Shop Smart to Fill Your Cart Prepare Healthy Meals Sample 2-Week Menus Resources for Professionals 10 Tips ... are here Home / MyPlate MyPlate Error message Notice : Undefined index: title ...

  19. Theoretical Development of Hybrid Simulation Applied to Plate Structures

    E-print Network

    Govindjee, Sanjay

    Theoretical Development of Hybrid Simulation Applied to Plate Structures Ahmed A. Bakhaty Khalid M, Berkeley PEER Report 2014-02 Pacific Earthquake Engineering Research Center Headquarters at the University of California, Berkeley January 2014 #12;ii #12;Abstract Hybrid simulation is a popular testing method

  20. Seismicity and plate tectonics in south central Alaska

    NASA Technical Reports Server (NTRS)

    Van Wormer, J. D.; Davies, J.; Gedney, L.

    1974-01-01

    Hypocenter distribution shows that the Benioff zone associated with the Aleutian arc terminates in interior Alaska some 75 km north of the Denali fault. There appears to be a break in the subducting Pacific plate in the Yentna River-Prince William Sound area which separates two seismically independent blocks, similar to the segmented structure reported for the central Aleutian arc.

  1. Acoustic nucleation of solid helium 4 on a clean glass plate

    E-print Network

    Balibar, Sébastien

    Acoustic nucleation of solid helium 4 on a clean glass plate X. Chavanne, S. Balibar, and F. Caupin to nucleate solid helium 4 on a clean glass plate. From the reflectance of light at the glass/helium interface mK, we have estimated the activation energy E for the nucleation on the glass plate; we have found E

  2. 17. Photocopy of drawing (original 8 x 101/2 inch plate ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. Photocopy of drawing (original 8 x 10-1/2 inch plate located in: USDA Forest Service, North Pacific Region, recreation handbook, date unknown). COMMUNITY BLDG., PLATE A-9 (enlarged from a 4x5 negative) - Austin Pass Warming Hut, Washington Highway 542, Glacier, Whatcom County, WA

  3. 14. Date Plate, 'C.O. #836, Dwg. #12A, Full Size. For ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Date Plate, 'C.O. #836, Dwg. #12A, Full Size. For Portal Strut with Date Plate `DP' see dwg. #12' - Southern Pacific Railroad Shasta Route, Bridge No. 301.85, Milepost 301.85, Pollard Flat, Shasta County, CA

  4. Accelerated plate tectonics.

    PubMed

    Anderson, D L

    1975-03-21

    The concept of a stressed elastic lithospheric plate riding on a viscous asthenosphere is used to calculate the recurrence interval of great earthquakes at convergent plate boundaries, the separation of decoupling and lithospheric earthquakes, and the migration pattern of large earthquakes along an arc. It is proposed that plate motions accelerate after great decoupling earthquakes and that most of the observed plate motions occur during short periods of time, separated by periods of relative quiescence. PMID:17799689

  5. Planet Earth: Plate Tectonics

    E-print Network

    Watts, A. B. "Tony"

    Planet Earth: Plate Tectonics Recommended Books: An Introduction to Our Dynamic Planet (ODP), 2007, ice and sediment for long periods of geological time (>105 a). · Controlled and passive (e, Problem sets etc Lecture 1: Plate Mechanics and Kinematics The Earth comprises 7 major plates and a number

  6. The Plate Boundary Observatory Cascadia Network: Development and Installation of a Large Scale Real-time GPS Network

    NASA Astrophysics Data System (ADS)

    Austin, K. E.; Blume, F.; Berglund, H. T.; Dittman, T.; Feaux, K.; Gallaher, W. W.; Mattioli, G. S.; Mencin, D.; Walls, C. P.

    2013-12-01

    The EarthScope Plate Boundary Observatory (PBO), through a NSF-ARRA supplement, has enhanced the geophysical infrastructure in in the Pacific Northwest by upgrading 232 Plate Boundary Observatory GPS stations to allow the collection and distribution of high-rate (1 Hz), low-latency (<1 s) data streams (RT-GPS). These upgraded stations supplemented the original 100 RT-GPS stations in the PBO GPS network. The addition of the new RT-GPS sites in the Pacific Northwest should spur new volcano and earthquake research opportunities in an area of great scientific interest and high geophysical hazard. Streaming RT-GPS data will enable researchers to detect and investigate strong ground motion during large geophysical events, including a possible plate-interface earthquake, which has implications for earthquake hazard mitigation. A total of 282 PBO stations were upgraded and added to the UNAVCO real-time GPS system, along with addition of 22 new meteorological instruments to existing PBO stations. Extensive testing of 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 UNAVCO's data infrastructure included evaluation and purchase of the Trimble Pivot Platform, servers, and additional hardware for archiving the high rate data. 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.

  7. Pressurized bellows flat contact heat exchanger interface

    NASA Technical Reports Server (NTRS)

    Voss, Fred E. (inventor); Howell, Harold R. (inventor); Winkler, Roger V. (inventor)

    1990-01-01

    Disclosed is an interdigitated plate-type heat exchanger interface. The interface includes a modular interconnect to thermally connect a pair or pairs of plate-type heat exchangers to a second single or multiple plate-type heat exchanger. The modular interconnect comprises a series of parallel, plate-type heat exchangers arranged in pairs to form a slot therebetween. The plate-type heat exchangers of the second heat exchanger insert into the slots of the modular interconnect. Bellows are provided between the pairs of fins of the modular interconnect so that when the bellows are pressurized, they drive the plate-type heat exchangers of the modular interconnect toward one another, thus closing upon the second heat exchanger plates. Each end of the bellows has a part thereof a thin, membrane diaphragm which readily conforms to the contours of the heat exchanger plates of the modular interconnect when the bellows is pressurized. This ensures an even distribution of pressure on the heat exchangers of the modular interconnect thus creating substantially planar contact between the two heat exchangers. The effect of the interface of the present invention is to provide a dry connection between two heat exchangers whereby the rate of heat transfer can be varied by varying the pressure within the bellows.

  8. Convergent plate margin east of North Island, New Zealand

    SciTech Connect

    Davey, F.J; Hampton, M.; Lewis, K.

    1986-07-01

    The Indian-Pacific plate boundary passes along the eastern margin of North Island, New Zealand, with the Pacific plate being thrust under the Indian plate to the west. The continental slope forming the Indian plate margin is broad with a well-formed series of trench slope basins and intervening ridges along the continental slope and shelf, subparallel to the margin, and continuing onto land. Multichannel seismic reflection data recorded across this margin show a thick (2.5-km) sedimentary section overlying oceanic basement in the deep-water part of the profile, and part of this sedimentary section is apparently being subducted under the accretionary prism. At the toe of the continental slope, nascent thrusts, often showing little apparent offset but a change in reflection amplitude, occur over a broad region. Well-defined trench slope basins show several episodes of basin formation and thrusting and are similar to structural interpretations for adjacent onshore basins. A bottom simulating reflector, which may delineate a gas-hydrate layer, can be traced over the midslope part of the profile. A major reflector, interpreted as the base of the accretionary prism, can be traced discontinuously to the coast where it coincides with the top of a zone of high seismicity, considered to mark the top of the subducted Pacific plate.

  9. An improved plating process

    NASA Technical Reports Server (NTRS)

    Askew, John C.

    1994-01-01

    An alternative to the immersion process for the electrodeposition of chromium from aqueous solutions on the inside diameter (ID) of long tubes is described. The Vessel Plating Process eliminates the need for deep processing tanks, large volumes of solutions, and associated safety and environmental concerns. Vessel Plating allows the process to be monitored and controlled by computer thus increasing reliability, flexibility and quality. Elimination of the trivalent chromium accumulation normally associated with ID plating is intrinsic to the Vessel Plating Process. The construction and operation of a prototype Vessel Plating Facility with emphasis on materials of construction, engineered and operational safety and a unique system for rinse water recovery are described.

  10. INTERNATIONAL PACIFIC RESEARCH CENTER

    E-print Network

    Wang, Yuqing

    INTERNATIONAL PACIFIC RESEARCH CENTER Annual Report April 2006 ­ March 2007 School of Ocean Research Center 1 2 The Year's Highlights 3 Research Accomplishments Indo-Pacific Ocean Climate 4 Regional-Ocean Ocean Climate: To understand climate variations in the Pacific and Indian oceans on inter- annual

  11. INTERNATIONAL PACIFIC RESEARCH CENTER

    E-print Network

    Wang, Yuqing

    INTERNATIONAL PACIFIC RESEARCH CENTER APRIL 2005­MARCH 2006 REPORT SCHOOL OF OCEAN AND EARTH Center 1 The Year's Highlights 3 Indo-Pacific Ocean Climate 4 Regional-Ocean Influences 10 Asian Ocean Climate: To understand climate variations in the Pacific and Indian oceans on interannual

  12. International Pacific Research Center

    E-print Network

    Wang, Yuqing

    International Pacific Research Center APRIL 2007­MARCH 2008 REPORT School of Ocean and Earth Center i Foreword ii iv Indo-Pacific Ocean Climate 1 Regional-Ocean Influences 13 Asian by the following broad research themes and goals of the IPRC Science Plan. Indo-Pacific Ocean Climate

  13. Plate Motion and Crustal Deformation Estimated with Geodetic Data from the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Argus, Donald F.; Heflin, Michael B.

    1995-01-01

    We use geodetic data taken over four years with the Global Positioning System (GPS) to estimate: (1) motion between six major plates and (2) motion relative to these plates of ten sites in plate boundary zones. The degree of consistency between geodetic velocities and rigid plates requires the (one-dimensional) standard errors in horizontal velocities to be approx. 2 mm/yr. Each of the 15 angular velocities describing motion between plate pairs that we estimate with GPS differs insignificantly from the corresponding angular velocity in global plate motion model NUVEL-1A, which averages motion over the past 3 m.y. The motion of the Pacific plate relative to both the Eurasian and North American plates is observed to be faster than predicted by NUVEL-1A, supporting the inference from Very Long B ase- line Interferometry (VLBI) that motion of the Pacific plate has speed up over the past few m.y. The Eurasia-North America pole of rotation is estimated to be north of NUVEL-1A, consistent with the independent hypothesis that the pole has recently migrated northward across northeast Asia to near the Lena River delta. Victoria, which lies above the main thrust at the Cascadia subduction zone, moves relative to the interior of the overriding plate at 30% of the velocity of the subducting plate, reinforcing the conclusion that the thrust there is locked beneath the continental shelf and slope.

  14. Plates and FEM

    NASA Astrophysics Data System (ADS)

    Blaauwendraad, J.

    The word plate is a collective term for systems in which transfer of forces occurs in two directions; walls, deep beams, floors and bridge slabs are all plates. We distinguish two main categories, plates that are loaded in their plane, and plates loaded perpendicularly to their plane. For both categories we give an approach with differential equations, such that a basic understanding is provided and for certain characteristic cases an exact solution can be determined. We follow the displacement method, working with differential equations. In plates that are loaded in their plane, the plane stress state is called the membrane state. All stress components are parallel to the mid- plane of the plate. In special cases we can simply determine the stresses.

  15. Hypervelocity plate acceleration

    SciTech Connect

    Marsh, S.P.; Tan, T.H.

    1991-01-01

    Shock tubes have been used to accelerate 1.5-mm-thick stainless steel plates to high velocity while retaining their integrity. The fast shock tubes are 5.1-cm-diameter, 15.2-cm-long cylinders of PBX-9501 explosive containing a 1.1-cm-diameter cylindrical core of low-density polystyrene foam. The plates have been placed directly in contact with one face of the explosive system. Plane-wave detonation was initiated on the opposite face. A Mach disk was formed in the imploding styrofoam core, which provided the impulse required to accelerate the metal plate to high velocity. Parametric studies were made on this system to find the effect of varying plate metal, plate thickness, foam properties, and addition of a barrel. A maximum plate velocity of 9.0 km/s has been observed. 6 refs., 17 figs.

  16. New estimates of subducted water from depths of extensional outer rise earthquakes at the Northwestern Pacific subduction zones

    NASA Astrophysics Data System (ADS)

    Emry, E. L.; Wiens, D. A.

    2012-12-01

    The presence of water within the subducting slab mantle may have important implications for subduction zone water budgets, intermediate depth earthquakes, and transport of water into Earth's deep mantle. However, the amount of water stored in hydrous slab mantle rocks prior to subduction is not well constrained. Large extensional faults formed as the plate bends at the subduction zone outer rise are thought to be the main pathway by which water can travel into and hydrate the slab mantle; yet for many subduction zones accurate depths of extensional outer rise faulting are also not well known. Therefore, we attempt to identify the maximum observed depth of extensional faulting, and thereby identify the possible depth extent of slab mantle hydration, by accurately locating and determining depths for outer rise and trench axis earthquakes at Northern and Western Pacific subduction zones. For each region, we relocate all earthquakes seaward of the trench axis as well as forearc earthquakes within 60 km landward of the trench axis using ISC arrival times and the hypocentroidal decomposition relative location algorithm. We then model P- and SH- waveforms and their associated depth phases for all earthquakes with Mw 5.0+ since 1990 that exhibit good signal-to-noise ratios and do not have shallow-dipping thrust focal mechanisms, which are indicative of subduction zone plate interface earthquakes. In total, we redetermined epicenters and depths for over 70 earthquakes at the Alaskan, Aleutian, Kamchatka, Kuril, Japan, and Izu-Bonin-Mariana trenches. We find that at most Pacific subduction zones there is evidence for extensional faulting down to 10-15 km within the top of the oceanic plate mantle, and in total, 95% of our analyzed extensional outer rise events occur within the crust or top 15 km of the mantle. However some regions, such as the Bonin and Aleutian Islands, show evidence for extensional faulting as deep as 20 km below the base of the crust. If the mantle of the subducting slab is hydrated down to ~15 km (with ~2-3.5 wt. % water), and assuming published values for the amount of water in the slab crust [1], then we expect that ~10^10 Tg/Myr of water are input into Northwestern Pacific subduction zones. This value for only the Northwestern Pacific subduction zones is then 10 times larger than previous global estimates [1] and indicates a need to reevaluate recent subduction water flux calculations. [1] Van Keken et al (2011), JGR, 116, B01401.

  17. Plating methods, a survey

    NASA Technical Reports Server (NTRS)

    Berkowitz, J. B.; Emerson, N. H.

    1972-01-01

    Results are presented of a comprehensive search of the literature available, much of which has been generated by the research centers of NASA and its contractors, on plating and coating methods and techniques. Methods covered included: (1) electroplating from aqueous solutions; (2) electroplating from nonaqueous solutions; (3) electroplating from fused-salt baths; (4) electroforming; (5) electroless plating, immersion plating, and mirroring; (6) electroplating from gaseous plasmas; and (7) anodized films and conversion coatings.

  18. Acceleration of metal plates

    SciTech Connect

    Marsh, S.P.; McQueen, R.G.; Tan, T.H.

    1989-01-01

    High-explosive charges have been used to accelerate stainless steel plates to velocities of 6-7 km/s. A two-stage system has been used in which the first stage is a plane-wave detonating system that accelerates the plate down a short barrel. The second stage consists of a hollow cylindrical charge through which the moving plate passes. After an adjustable delay this charge is detonated on the outer circumference of the entry side of the charge. Flash radiographs and witness plates show no breakup in the first stage but bowing and frequent breakup in the second stage. 6 figs.

  19. Deformation-related volcanism in the Pacific Ocean linked to the Hawaiian-Emperor bend

    NASA Astrophysics Data System (ADS)

    O'Connor, John M.; Hoernle, Kaj; Müller, R. Dietmar; Morgan, Jason P.; Butterworth, Nathaniel P.; Hauff, Folkmar; Sandwell, David T.; Jokat, Wilfried; Wijbrans, Jan R.; Stoffers, Peter

    2015-05-01

    Ocean islands, seamounts and volcanic ridges are thought to form above mantle plumes. Yet, this mechanism cannot explain many volcanic features on the Pacific Ocean floor and some might instead be caused by cracks in the oceanic crust linked to the reorganization of plate motions. A distinctive bend in the Hawaiian-Emperor volcanic chain has been linked to changes in the direction of motion of the Pacific Plate, movement of the Hawaiian plume, or a combination of both. However, these links are uncertain because there is no independent record that precisely dates tectonic events that affected the Pacific Plate. Here we analyse the geochemical characteristics of lava samples collected from the Musicians Ridges, lines of volcanic seamounts formed close to the Hawaiian-Emperor bend. We find that the geochemical signature of these lavas is unlike typical ocean island basalts and instead resembles mid-ocean ridge basalts. We infer that the seamounts are unrelated to mantle plume activity and instead formed in an extensional setting, due to deformation of the Pacific Plate. 40Ar/39Ar dating reveals that the Musicians Ridges formed during two time windows that bracket the time of formation of the Hawaiian-Emperor bend, 53-52 and 48-47 million years ago. We conclude that the Hawaiian-Emperor bend was formed by plate-mantle reorganization, potentially triggered by a series of subduction events at the Pacific Plate margins.

  20. Warping and cracking of the Pacific plate by thermal contraction

    E-print Network

    Fialko, Yuri

    that convective rolls or mantle plumes are not required. INDEX TERMS: 1208 Geodesy and Gravity: Crustal movements) Gravity lineaments are prominent at 140­200 km wavelength and are aligned in the direction of absolute), including small-scale convective rolls [Haxby and Weissel, 1986]; mini hot spots [Fleitout et al., 1989

  1. Geographical distribution of shear wave anisotropy within marine sediments in the northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Tonegawa, Takashi; Fukao, Yoshio; Fujie, Gou; Takemura, Shunsuke; Takahashi, Tsutomu; Kodaira, Shuichi

    2015-12-01

    In the northwestern Pacific, the elastic properties of marine sediments, including P-wave velocities ( Vp) and S wave velocities ( Vs), have recently been constrained by active seismic surveys. However, information on S anisotropy associated with the alignments of fractures and fabric remains elusive. To obtain such information, we used ambient noise records observed by ocean-bottom seismometers at 254 sites in the northwestern Pacific to calculate the auto-correlation functions for the S reflection retrieval from the top of the basement. For these S reflections, we measured differential travel times and polarized directions to reveal the potential geographical systematic distribution of S anisotropy. As a result, the observed differential times between fast and slow axes were at most 0.05 s. The fast polarization axes tend to align in the trench-parallel direction in the outer rise region. In particular, their directions changed systematically in accordance with the direction of the trench axis, which changes sharply across the junction of the Kuril and Japan trenches. We consider that a contributing factor for the obtained S anisotropy within marine sediments in the outer rise region is primarily aligned fractures due to the tensional stresses associated with the bending of the Pacific Plate. Moreover, numerical simulations conducted by using the three-dimensional (3D) finite difference method for isotropic and anisotropic media indicates that the successful extraction of S anisotropic information from the S reflection observed in this study is obtained from near-vertically propagating S waves due to extremely low Vs within marine sediments. In addition, we conducted an additional numerical simulation with a realistic velocity model to confirm whether S reflections below the basement can be extracted or not. The resultant auto-correlation function shows only S reflections from the top of the basement. It appears that such near-vertically propagating S waves obscure S reflections from interfaces below the basement.

  2. Author's personal copy Plate tectonic reconstructions with continuously closing plates$

    E-print Network

    Bower, Dan J.

    Author's personal copy Plate tectonic reconstructions with continuously closing plates$ Michael May 2011 Keywords: Geodynamics Plate tectonics a b s t r a c t We present a new algorithm for modeling margins and plates, traditional global plate tectonic reconstructions have become inadequate

  3. SKITTER/implement mechanical interface

    NASA Technical Reports Server (NTRS)

    Cash, John Wilson, III; Cone, Alan E.; Garolera, Frank J.; German, David; Lindabury, David Peter; Luckado, Marshall Cleveland; Murphey, Craig; Rowell, John Bryan; Wilkinson, Brad

    1988-01-01

    SKITTER (Spacial Kinematic Inertial Translatory Tripod Extremity Robot) is a three-legged transport vehicle designed to perform under the unique environment of the moon. The objective of this project was to design a mechanical interface for SKITTER. This mechanical latching interface will allow SKITTER to use a series of implements such as drills, cranes, etc., and perform different tasks on the moon. The design emphasized versatility and detachability; that is, the interface design is the same for all implements, and connection and detachment is simple. After consideration of many alternatives, a system of three identical latches at each of the three interface points was chosen. The latching mechanism satisfies the design constraints because it facilitates connection and detachment. Also, the moving parts are protected from the dusty environment by housing plates.

  4. Blue Willow Story Plates

    ERIC Educational Resources Information Center

    Fontes, Kris

    2009-01-01

    In the December 1997 issue of "SchoolArts" is a lesson titled "Blue Willow Story Plates" by Susan Striker. In this article, the author shares how she used this lesson with her middle-school students many times over the years. Here, she describes a Blue Willow plate painting project that her students made.

  5. The age and origin of the Pacific islands: a geological overview.

    PubMed

    Neall, Vincent E; Trewick, Steven A

    2008-10-27

    The Pacific Ocean evolved from the Panthalassic Ocean that was first formed ca 750 Ma with the rifting apart of Rodinia. By 160 Ma, the first ocean floor ascribed to the current Pacific plate was produced to the west of a spreading centre in the central Pacific, ultimately growing to become the largest oceanic plate on the Earth. The current Nazca, Cocos and Juan de Fuca (Gorda) plates were initially one plate, produced to the east of the original spreading centre before becoming split into three. The islands of the Pacific have originated as: linear chains of volcanic islands on the above plates either by mantle plume or propagating fracture origin, atolls, uplifted coralline reefs, fragments of continental crust, obducted portions of adjoining lithospheric plates and islands resulting from subduction along convergent plate margins. Out of the 11 linear volcanic chains identified, each is briefly described and its history summarized. The geology of 10 exemplar archipelagos (Japan, Izu-Bonin, Palau, Solomons, Fiji, New Caledonia, New Zealand, Society, Galápagos and Hawaii) is then discussed in detail. PMID:18768382

  6. 11. GIRDER PARTIAL ELEVATION AND SECTIONS, 80 FOOT THROUGH PLATE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. GIRDER PARTIAL ELEVATION AND SECTIONS, 80 FOOT THROUGH PLATE GIRDER SPAN. (Also includes a Marking Diagram and a schedule of parts.) American Bridge Company, Ambridge Plant No. 5, sheet no. 1, dated April 7, 1928, order no. F5073. For U.S. Steel Products Company, Pacific Coast Depot, order no. SF578. For Southern Pacific Company, order no. 8873-P-28746. Scale 1/4 inch to one foot. - Napa River Railroad Bridge, Spanning Napa River, east of Soscol Avenue, Napa, Napa County, CA

  7. Plate Tectonics Prof. Thomas Herring

    E-print Network

    Herring, Thomas

    1 Plate Tectonics Prof. Thomas Herring MIT 05/14/02 Lexington HS Plate tectonics 2 Contact/14/02 Lexington HS Plate tectonics 3 Overview · Development of the Plate tectonic theory · Geological Data ­ Sea-floor spreading ­ Fault types from earthquakes ­ Transform faults ­ Today's measurements of plate tectonics 05

  8. Plating To Reinforce Welded Joints

    NASA Technical Reports Server (NTRS)

    Otousa, J. E.

    1982-01-01

    Electrodeposition used to strengthen welded joints gouged, nicked, or suffered other mechanical damage. Plating cell, typically of acrylic plastic such as poly (Methylmetacrylate), is assembled around part to be plated. Areas not to be plated are masked with plater's tape. Weld area is plated in standard nickel-plating process.

  9. Trench migration and upper plate strain over a convecting mantle

    NASA Astrophysics Data System (ADS)

    Husson, Laurent

    2013-04-01

    Trench motion and upper plate deformation ultimately respond to mantle flow. Herein I build upon the mantle flow model results of Conrad and Behn (2010) and compute the drag forces underneath all plates, and show that they control the dynamics of plates and plate boundaries. The small misfit angle between between the traction azimuths of mantle traction and absolute plate motion corroborates the idea that convective mantle drag is a prominent driver of plate tectonics. Less intuitive is the fact that the interplay between the drag forces from the upper and lower plates, that amounts to -5 to 8.5 TN/m (per unit trench length), dictates both trench migration rates and upper plate deformation. At odds with the classic view that assigns the prime role to the idiosyncrasies of subduction zones (slab age, interplate friction, water content etc), I find that the intrinsic properties of subduction zones in fact only modulate this behavior. More specifically, the mean value of the integrated trenchward mantle drag force from the lower and upper plates (from -2 to 6.5 TN/m) controls upper plate deformation. Conversely, it is the difference between the lower and upper plates mantle drag forces (from -3 to 10 TN/m) that controls trench migration rates. In addition, I find that a minimum trenchward force of ~2.5 TN/m must be supplied by mantle drag before trenches can actually advance, and before upper plates undergo compression. This force results from the default tendency of slabs to rollback when solely excited by their own buoyancy, and is thus the effective tensional force that slab pull exerts on the plate interface.

  10. Trench migration and upper plate strain over a convecting mantle

    NASA Astrophysics Data System (ADS)

    Husson, Laurent

    2012-12-01

    Trench motion and upper plate deformation ultimately respond to mantle flow. Herein I build upon the mantle flow model results of Conrad and Behn (2010) and compute the drag forces underneath all plates, and show that they control the dynamics of plates and plate boundaries. The small misfit angle between between the traction azimuths of mantle traction and absolute plate motion corroborates the idea that convective mantle drag is a prominent driver of plate tectonics. Less intuitive is the fact that the interplay between the drag forces from the upper and lower plates, that amounts to -5 to 8.5 × 1012 N m-1 (per unit trench length), dictates both trench migration rates and upper plate deformation. At odds with the classic view that assigns the prime role to the idiosyncrasies of subduction zones (slab age, interplate friction, water content etc), I find that the intrinsic properties of subduction zones in fact only modulate this behavior. More specifically, the mean value of the integrated trenchward mantle drag force from the lower and upper plates (from -2 to 6.5 × 1012 N m-1) controls upper plate deformation. Conversely, it is the difference between the lower and upper plates mantle drag forces (from -3 to 10 × 1012 N m-1) that controls trench migration rates. In addition, I find that a minimum trenchward force of ˜2.5 × 1012 N m-1 must be supplied by mantle drag before trenches can actually advance, and before upper plates undergo compression. This force results from the default tendency of slabs to rollback when solely excited by their own buoyancy, and is thus the effective tensional force that slab pull exerts on the plate interface.

  11. The surface and through crack problems in layered orthotropic plates

    NASA Technical Reports Server (NTRS)

    Erdogan, Fazil; Wu, Binghua

    1991-01-01

    An analytical method is developed for a relatively accurate calculation of Stress Intensity Factors in a laminated orthotropic plate containing a through or part-through crack. The laminated plate is assumed to be under bending or membrane loading and the mode 1 problem is considered. First three transverse shear deformation plate theories (Mindlin's displacement based first-order theory, Reissner's stress-based first-order theory, and a simple-higher order theory due to Reddy) are reviewed and examined for homogeneous, laminated and heterogeneous orthotropic plates. Based on a general linear laminated plate theory, a method by which the stress intensity factors can be obtained in orthotropic laminated and heterogeneous plates with a through crack is developed. Examples are given for both symmetrically and unsymmetrically laminated plates and the effects of various material properties on the stress intensity factors are studied. In order to implement the line-spring model which is used later to study the surface crack problem, the corresponding plane elasticity problem of a two-bonded orthotropic plated containing a crack perpendicular to the interface is also considered. Three different crack profiles: an internal crack, an edge crack, and a crack terminating at the interface are considered. The effect of the different material combinations, geometries, and material orthotropy on the stress intensity factors and on the power of stress singularity for a crack terminating at the interface is fully examined. The Line Spring model of Rice and Levy is used for the part-through crack problem. The surface crack is assumed to lie in one of the two-layered laminated orthotropic plates due to the limitation of the available plane strain results. All problems considered are of the mixed boundary value type and are reduced to Cauchy type of singular integral equations which are then solved numerically.

  12. An estimate of tidal and non-tidal modulations of plate subduction speed in the transition zone in the Tokai district

    NASA Astrophysics Data System (ADS)

    Tanaka, Yoshiyuki; Yabe, Suguru; Ide, Satoshi

    2015-12-01

    Non-volcanic tremors and slow slip events in subduction zones have been found to be triggered by small external stress disturbances, as demonstrated by the synchronization of temporal variations in tremor rate with diurnal and semi-diurnal tides. Therefore, long-term variations in tremor rate might be predicted by amplitude modulations of diurnal and semi-diurnal tides at decadal time scales. Given that tremors and slow slips are shear slip on the plate boundary, their long-term variations must be associated with fluctuations in plate subduction speed below the seismogenic zone. In previous work, we showed a good correlation between long-term seismicity and empirically calculated tremor rate based on observed tidal levels in the Nankai region, western Japan. Here, we present an improved method of modeling long-term slip rate fluctuation based on the calculation of Coulomb stress due to ocean and solid earth tides on the plate interface. We also include the effects of non-tidal ocean variations, such as the Pacific Decadal Oscillation and the Kuroshio Current, employing an ocean model developed by the Japan Meteorological Agency. We apply the method to the Tokai district, where the effects of the Kuroshio Current are large, and demonstrate the importance of considering non-tidal effects. Our calculated slip rate fluctuations could amount to 1 mm/year in decadal scales, and periods with faster rates partly corresponded to variations in seismicity. Slow slip events in the study region weakly corresponded to times of higher stress.

  13. Numerical simulation of lithospheric plate dynamics and seismicity

    NASA Astrophysics Data System (ADS)

    Ismail-Zadeh, A.; Rozenberg, V.; Melnikova, L.; Soloviev, A.

    2009-12-01

    We model the lithospheric plate dynamics as an interaction of rigid blocks (spherical segments) and faults separating them. The spherical block-and-fault dynamics (BAFD) model consists of 15 blocks approximating tectonic plates and 5 additional blocks representing parts of the plates, where deep seismicity is observed. The blocks move as a consequence of the prescribed underlying mantle motion. The block displacements at any time are defined so that the system of the blocks is in a quasi-static equilibrium state. Because of the block rigidity, all deformations take place in the fault zones. The interaction between the spherical blocks is visco-elastic (a state of stress accumulation), so long as the ratio of the stress to the pressure is below a certain strength level. When this level is exceeded in some part of a fault, a stress-drop (a synthetic earthquake) occurs in accordance with the dry friction law. Immediately following the earthquake and for some period of time, the corresponding parts of the faults are in a state of creep. Catalogs of synthetic earthquakes are produced as results of numerical simulations. Using the catalogs of synthetic events we can study frequency-magnitude relationships, clustering of the events, long-range interaction of earthquakes, earthquake mechanisms, and fault slips. The model catalogs obtained reflect important features of global seismicity: (i) two large seismic belts, the circum-Pacific and Alpine-Himalayan; (ii) extensive, but less pronounced, seismicity at mid-oceanic ridges; and (iii) increased seismic activity associated with triple junctions of plate boundaries. The model results are consistent with the observations: Nazca/South America, Cocos/Caribbean, India/Eurasia, California region, Arabia/Eurasia, northern Australia, and the Philippine plate margin are marked in the model as the regions prone to strong earthquakes. The modeled seismic activity is moderate at the boundaries such as the southern Pacific plate, Nazca/Pacific, east and southwest of Africa, India/Australia, and North America/Eurasia.

  14. Earthquakes and plate tectonics.

    USGS Publications Warehouse

    Spall, H.

    1982-01-01

    Earthquakes occur at the following three kinds of plate boundary: ocean ridges where the plates are pulled apart, margins where the plates scrape past one another, and margins where one plate is thrust under the other. Thus, we can predict the general regions on the earth's surface where we can expect large earthquakes in the future. We know that each year about 140 earthquakes of magnitude 6 or greater will occur within this area which is 10% of the earth's surface. But on a worldwide basis we cannot say with much accuracy when these events will occur. The reason is that the processes in plate tectonics have been going on for millions of years. Averaged over this interval, plate motions amount to several mm per year. But at any instant in geologic time, for example the year 1982, we do not know, exactly where we are in the worldwide cycle of strain build-up and strain release. Only by monitoring the stress and strain in small areas, for instance, the San Andreas fault, in great detail can we hope to predict when renewed activity in that part of the plate tectonics arena is likely to take place. -from Author

  15. High loading uranium plate

    SciTech Connect

    Wiencek, T.C.; Domagala, R.F.; Thresh, H.R.

    1990-10-16

    Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pari of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat hiving a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

  16. PACIFIC NORTHWEST CYBER SUMMIT

    SciTech Connect

    Lesperance, Ann M.; Matlock, Gordon W.; Becker-Dippmann, Angela S.; Smith, Karen S.

    2013-08-07

    On March 26, 2013, the Snohomish County Public Utility District (PUD) and the U.S. Department of Energy’s (DOE’s) Pacific Northwest National Laboratory (PNNL) jointly hosted the Pacific Northwest Cyber Summit with the DOE’s Office of Electricity Delivery and Energy Reliability, the White House, Washington State congressional delegation, Washington State National Guard, and regional energy companies.

  17. Tropical Pacific moisture variability

    NASA Technical Reports Server (NTRS)

    Mcguirk, James P.

    1989-01-01

    Research objectives are to: (1) describe the synoptic scale variability of moisture over the tropical Pacific Ocean; (2) describe the systems leading to this variability; and (3) develop and implement satellite analysis procedures to facilitate (1) and (2) over the data sparse Pacific.

  18. A great earthquake rupture across a rapidly evolving three-plate boundary.

    PubMed

    Furlong, Kevin P; Lay, Thorne; Ammon, Charles J

    2009-04-10

    On 1 April 2007 a great, tsunamigenic earthquake (moment magnitude 8.1) ruptured the Solomon Islands subduction zone at the triple junction where the Australia and Solomon Sea-Woodlark Basin plates simultaneously underthrust the Pacific plate with different slip directions. The associated abrupt change in slip direction during the great earthquake drove convergent anelastic deformation of the upper Pacific plate, which generated localized uplift in the forearc above the subducting Simbo fault, potentially amplifying local tsunami amplitude. Elastic deformation during the seismic cycle appears to be primarily accommodated by the overriding Pacific forearc. This earthquake demonstrates the seismogenic potential of extremely young subducting oceanic lithosphere, the ability of ruptures to traverse substantial geologic boundaries, and the consequences of complex coseismic slip for uplift and tsunamigenesis. PMID:19359581

  19. The cascading effects of absolute reference frames and geomagnetic polarity timescales on global plate motions

    NASA Astrophysics Data System (ADS)

    Zahirovic, S.; Seton, M.; Müller, R. D.; Torsvik, T. H.

    2011-12-01

    Global plate motion models use Africa and the Pacific as the base of plate rotation hierarchies, with many other plates moving relative to them. Relative plate motions in the Mesozoic are generally well resolved where seafloor spreading histories are preserved to the present-day. However, the choice of absolute reference frames, whether they are fixed-hotspot, moving-hotspot, true-polar wander-corrected or pure paleomagnetic, can have significant consequences for the absolute plate velocities of smaller plates that are at the mercy of the cascading effects of movement within a complex plate motion hierarchy. We use GPlates to sample plate velocities through time at equally spaced mesh nodes that are contained within continuously closing plate polygons. We calculate root-mean square plate velocities to isolate the effects of different absolute reference frames on absolute plate velocity trends. Apart from being a quality-control tool for the creation of global plate motion models, this approach allows us to track the source of plate velocity spikes, some of which may be indicative of plate reorganisation events. We use a similar approach to test whether alternative geomagnetic polarity time-scales introduce or help reduce anomalous plate velocity fluctuations in global plate motion models. The choice of timescales can affect the seafloor spreading rates partitioned across stage rotations and models of sea level change. Such a workflow may help test alternative timescales, in order to study the model-dependence and controversies that have recently surfaced regarding proposed plate reorganisation events and the mid-Cretaceous seafloor spreading pulse.

  20. Tectonic Plate Movement.

    ERIC Educational Resources Information Center

    Landalf, Helen

    1998-01-01

    Presents an activity that employs movement to enable students to understand concepts related to plate tectonics. Argues that movement brings topics to life in a concrete way and helps children retain knowledge. (DDR)

  1. Reduction of astrometric plates

    NASA Technical Reports Server (NTRS)

    Stock, J.

    1984-01-01

    A rapid and accurate method for the reduction of comet or asteroid plates is described. Projection equations, scale length correction, rotation of coordinates, linearization, the search for additional reference stars, and the final solution are examined.

  2. Positive battery plate

    NASA Technical Reports Server (NTRS)

    Rowlette, John R. (Inventor)

    1985-01-01

    The power characteristics of a lead acid battery are improved by incorporating a dispersion of 1 to 10% by weight of a thermodynamically stable conductivity additive, such as conductive tin oxide coated glass fibers (34) of filamentary glass wool (42) in the positive active layer (32) carried on the grid (30) of the positive plate (16). Positive plate potential must be kept high enough to prevent reduction of the tin oxide to tin by utilizing an oversized, precharged positive paste.

  3. Fractal multifiber microchannel plates

    NASA Technical Reports Server (NTRS)

    Cook, Lee M.; Feller, W. B.; Kenter, Almus T.; Chappell, Jon H.

    1992-01-01

    The construction and performance of microchannel plates (MCPs) made using fractal tiling mehtods are reviewed. MCPs with 40 mm active areas having near-perfect channel ordering were produced. These plates demonstrated electrical performance characteristics equivalent to conventionally constructed MCPs. These apparently are the first MCPs which have a sufficiently high degree of order to permit single channel addressability. Potential applications for these devices and the prospects for further development are discussed.

  4. Motion and rigidity of the Pacific Plate and implications for plate boundary deformation

    E-print Network

    Tregoning, Paul

    zones in both regions are wider than previously believed. INDEX TERMS: 1206 Geodesy and Gravity: Crustal movements--interplate (8155); 1208 Geodesy and Gravity: Crustal movements--intraplate (8110); 1243 Geodesy

  5. A computational model for predicting damage evolution in laminated composite plates 

    E-print Network

    Phillips, Mark Lane

    1999-01-01

    The feasibility of producing a model capable of predicting the evolution of interface degradation, matrix cracking, and delimitation at multiple sites in laminated continuous fiber composite plates subjected to monotonic ...

  6. Plate convergence west of Patagonia and the Antarctic Peninsula since 61 Ma

    NASA Astrophysics Data System (ADS)

    Eagles, Graeme; Scott, Benjamin G. C.

    2014-12-01

    A new plate kinematic model portrays plate motions immediately west and south of Drake Passage in the southeast Pacific Ocean. Overall intermediate-to-slow rate spreading generated oceanic lithosphere as the Phoenix plate diverged from the Antarctic plate. The model shows a history of Phoenix plate motion that is interpretable as having been affected by a northeast-increasing gradient in the slab pull force since chron 18 (39 Ma), during which time newer, less dense lithosphere was subducting in the southwest than in the northeast. The model allows first calculations of Phoenix-Farallon (Nazca) plate motion parameters in the south Pacific plate circuit. Using these parameters, it is possible to show that the simplest assumptions about the ridge's segmentation, length and migration are consistent with existing suggestions of its location from consideration of slab window-related volcanism at sites in South America around 50 and 20 Ma. The parameters thus define ridge locations that can be used to define which plates were subducting beneath South America and the Magallanes and Antarctic plates, and when. We consider the relationships between the plate convergence rate, obliquity and the history of magmatism on the Antarctic Peninsula and at the North Patagonian batholith, showing that magmatic pulses can be related to accelerations in the plate convergence rate. Between these settings, Phoenix-South American plate motion was almost parallel to the Fuegian trench. Here, magmatism in Paleocene to early Miocene times must be related to the presence of a slab subducted beneath the region by the less oblique collision further north. Later magmatism can be related to migration of the Phoenix-Farallon ridge and Phoenix-Farallon-Antarctic triple junction into the area south of the Fuegian margin, which brought it into slow low-obliquity convergence with first Farallon and then Antarctic plate lithosphere.

  7. Phase field modeling of Widmanstatten plate formation in Zr-2.5Nb material

    NASA Astrophysics Data System (ADS)

    Choudhuri, G.; Chakraborty, S.; Srivastava, D.; Dey, G. K.

    Growth of Widmanstatten side-plates from pre-nucleated ? in a matrix of ? is a diffusion controlled process. The phase-field approach is formulated for Widmanstatten side plate formation through ?-Zr (B.C.C) ? ?-Zr (HCP) transformation in binary substitutional Zr-2.5Nb alloy. Using Gibbs energy functional and diffusional mobility, microstructural evolution of parallel side-plates from pre-nucleated ? phase has been simulated. The highly anisotropic nature of Widmanstatten plate and the presence of thin interface at the parent-product interface make the task challenging for FEM analysis. Based on this model, an estimate on the range of temperature over which Widmanstatten parallel side-plates can form is estimated and the extent of anisotropy of surface free energy on the morphology of the plates is analyzed.

  8. Caribbean plate interactions

    SciTech Connect

    Ball, M. )

    1993-02-01

    Vector analysis of plate motions, derived from studies of Atlantic magnetic lineations and fracture zone trends, indicates the following relative movements between the Caribbean, North American, and South American Plates. (1) During Early Jurassic to Early Cretaceous, the North American Plate moved 1900 km westward and 900 km northward relative to the South American Plate. A broad zone including the Caribbean region, i.e., the zone between the North and South America Plates, was a site of left-lateral shear and north-south extension. (2) During Early Cretaceous to Late Cretaceous, the North American Mate moved an additional 1200 km westward relative to South America across this zone. (3) During Late Cretaceous to the end of the Eocene, the North American Plate moved 200 km westward and 400 km northward relative to the South American Plate. (4) From the end of the Eocene to near the end of the Miocene, North America converged on South America some 200 km and moved 100 km eastward relative to it. Through the Mesozoic and earliest Tertiary history of the Caribbean, the region was a shear zone within which left-lateral displacement exceeded 3000 km and north-south extension exceeded 1300 km. In regard to time, 80% of the history of the Caribbean region is one of north-south extension and left-lateral shear. In terms of space, 97% of the shear is left-lateral and the ratio of divergence versus convergence is 7 to 1. Thus, characterizing the Caribbean region, and the Atlantic to its east, as a zone of north-south extension and left-lateral shear, is a fair generalization.

  9. Survey of ion plating sources. [conferences

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1979-01-01

    Based on the type of evaporation source, gaseous media and mode of transport, the following is discussed: resistance, electron beam, sputtering, reactive and ion beam evaporation. Ionization efficiencies and ion energies in the glow discharge determine the percentage of atoms which are ionized under typical ion plating conditions. The plating flux consists of a small number of energetic ions and a large number of energetic neutrals. The energy distribution ranges from thermal energies up to a maximum energy of the discharge. The various reaction mechanisms which contribute to the exceptionally strong adherence - formation of a graded sustrate/coating interface are not fully understood, however the controlling factors are evaluated. The influence of process variables on the nucleation and growth characteristics are illustrated in terms of morphological changes which affect the mechanical and tribological properties of the coating.

  10. Cadmium plating replacements

    SciTech Connect

    Nelson, M.J.; Groshart, E.C.

    1995-03-01

    The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

  11. Cadmium plating replacements

    NASA Technical Reports Server (NTRS)

    Nelson, Mary J.; Groshart, Earl C.

    1995-01-01

    The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

  12. Changjiang (Yangtze) Pacific Ocean

    E-print Network

    REPUBLIC of CHINA Sea of Japan Huizhou Bay Seahan Bay Liaodong Bay JAPAN Bay Kyunggi Shangdong Peninsula Bohai Sea Yellow Sea East China Sea Pacific Ocean Han River SOUTH KOREA NORTH KOREA Yalu River TAIWAN

  13. Plate-mantle coupling from post-Pangea plate kinematics

    NASA Astrophysics Data System (ADS)

    Zahirovic, Sabin; Dietmar Müller, R.; Seton, Maria; Flament, Nicolas

    2015-04-01

    Convection in the Earth's mantle that involves plates at the surfaces gives rise to plate velocities that vary through time and depend on the balance of plate boundary forces, with the present-day providing a snapshot of this ongoing process. However, present-day plate velocities do not capture plate behaviour over geologically representative timeframes and thus cannot be used to evaluate factors limiting plate velocities. Previous studies investigated the effects of continental keels on plate speeds by either using the present-day snapshot or a limited number of reconstructed plate configurations, often leading to conflicting results. For example, an early assumption was that continental keels (especially cratons) were unlikely to impede fast plate motions because India's velocity approached ~20 cm/yr in the Eocene prior to the collision with Eurasia. We employ a modern plate reconstruction approach with evolving global topological plate boundaries for the post-Pangea timeframe (since 200 Ma) to evaluate factors controlling plate velocities. Plate boundary configurations and plate velocities are extracted from the open-source and cross-platform plate reconstruction package GPlates (www.gplates.org) at 1 Myr intervals. For each plate, at each timestep, the area of continental and cratonic lithosphere is calculated to evaluate the effect on plate velocities. Our results support that oceanic plates tend to be 2-3 times faster than plates with large portion of continental plate area, consistent with predictions of numerical models of mantle convection. The fastest plates (~8.5 cm/yr RMS) are dominated by oceanic plate area and high subducting portion of plate perimeter, while the slowest plates (~2.6-2.8 cm/yr RMS) are dominated by continental plate area and bounded by transforms and mid-oceanic ridge segments. Importantly, increasing cratonic fractions (both Proterozoic and Archean lithosphere) significantly impede plate velocities, suggesting that deep continental keels impinge on asthenospheric flow to increase shear traction, thus anchoring the plate in the more viscous mantle transition zone. However, plates with significant cratonic fragments exhibit short-lived (~10 Myr) accelerations, such as the rapid motion of the Indian plate that is correlated with plume head arrivals as recorded by large igneous province (LIPs) emplacement, highlighting the necessity to analyse plate velocities over long geological timeframes. By evaluating factors controlling plate velocities in the post-Pangea timeframe, simple principles can be applied to highlight potential plate velocity artefacts for Paleozoic and earlier times for which no hotspot tracks, nor in-situ seafloor spreading histories, are preserved. Based on the post-Pangea timeframe, a principle that can be applied to pre-Pangea times is that plates with less than ~50% continental area can reach RMS velocities of ~20 cm/yr, while plates with more than 50% continental fraction do not exceed RMS velocities of ~10 cm/yr. Similarly, plates with large portions of continental or cratonic area with RMS velocities exceeding ~15 cm/yr for more than ~10 Myr should be flagged as potential artefacts requiring further justification of plate driving forces in such scenarios.

  14. Hyperbolic Interfaces

    E-print Network

    Luca Giomi

    2012-09-25

    Fluid interfaces, such as soap films, liquid droplets or lipid membranes, are known to give rise to several special geometries, whose complexity and beauty continue to fascinate us, as observers of the natural world, and challenge us as scientists. Here I show that a special class of surfaces of constant negative Gaussian curvature can be obtained in fluid interfaces equipped with an orientational ordered phase. These arise in various soft and biological materials, such as nematic liquid crystals, cytoskeletal assemblies, or hexatic colloidal suspensions. The purely hyperbolic morphology originates from the competition between surface tension, that reduces the area of the interface at the expense of increasing its Gaussian curvature, and the orientational elasticity of the ordered phase, that in turn suffers for the distortion induced by the underlying curvature.

  15. Recent Intraplate Volcanism on Young Pacific Seafloor

    NASA Astrophysics Data System (ADS)

    Scheirer, D.; Forsyth, D.; Donnelly, K.; Webb, S.; Hosford, A.; Langmuir, C.

    2002-05-01

    On leg 16 of R/V Melville's Cook Expedition (Nov-Dec 2001), we discovered evidence for recent volcanism along ridges and seamounts of young Pacific plate between 12-16degS. The patterns of this intraplate activity will shed light on the circulation and melting of mantle and the nature of lithospheric deformation associated with volcanic ridges and seamount chains beyond the region influenced by seafloor spreading processes at the neighboring East Pacific Rise. As part of the GLIMPSE experiment, we collected multibeam, sidescan sonar, potential field, seismic refraction, single-channel reflection, and microearthquake data over crust ranging in age from 1-7 Ma, and we collected rocks at 46 successful dredge and waxcore stations. The greater sidescan sonar reflectivity of the Hotu, Matua, and Brown volcanic areas relative to adjacent seafloor indicates their substantially younger ages. This is confirmed by the recovery of abundant, fresh lavas in the dredge hauls. The Hotu complex is less reflective than the adjacent Matua complex; given the age-resolution of sonar reflectivity, we infer that Hotu was last active between 100-200 ka and that Matua may have been very recently active. This trend is confirmed by the freshness of the basaltic glass from these two sites and will be confirmed directly with Ar-Ar dating of the basalts. The Sojourn Ridge, a 400 km long ridge to the north of Hotu and Matua, does not have sonar or sample evidence for recent activity, but the Brown Ridge immediately to the east (on younger crust) is very reflective and returned very fresh glasses along its nearly 200 km length. The Thanksgiving Seamounts, a chain mid-way between Hotu/Matua and Sojourn/Brown, does not appear to be recently active, based on sonar and sample inspection; it formed as a near-axis seamount chain similar to many chains identified in this area of the Pacific. Substantial melts are produced locally in the mantle beneath plate aged 1-7 Ma, these melts erupt on the seafloor over distances 100-200 km in the direction of plate motion, and properties of the Pacific lithosphere and asthenosphere in this area lead to this unusual intraplate activity. Continued geochemical and geophysical analysis, including results from an ongoing year-long passive OBS experiment, will demonstrate how mantle motions such as small-scale, longitudinal convection lead to melting and how properties of the lithosphere impede or promote ascent of that melt to the seafloor.

  16. Payoff in the pacific.

    PubMed

    Schneider, P

    1998-08-01

    Asia Pacific economies are struggling to cope with the past year's series of financial catastrophies and regain the market stature and confidence they once enjoyed. Despite the turmoil, all industries including healthcare continue to demonstrate their commitment toward privatization and modernization through technology. Advances in healthcare IT in the Asia Pacific region are narrowing the differences in healthcare between East and West. Is the information age speeding healthcare toward a global standard? PMID:10182498

  17. Estimation of current plate motions in Papua New Guinea from Global Positioning System observations

    NASA Astrophysics Data System (ADS)

    Tregoning, Paul; Lambeck, Kurt; Stolz, Art; Morgan, Peter; McClusky, Simon C.; van der Beek, Peter; McQueen, Herbert; Jackson, Russell J.; Little, Rodney P.; Laing, Alex; Murphy, Brian

    1998-06-01

    Plate tectonic motions have been estimated in Papua New Guinea from a 20 station network of Global Positioning System sites that has been observed over five campaigns from 1990 to 1996. The present velocities of the sites are consistent with geological models in which the South Bismarck, Woodlark, and Solomon Sea Plates form the principal tectonic elements between the Pacific and Australian Plates in this region. Active spreading is observed on the Woodlark Basin Spreading Centre but at a rate that is about half the rate determined from magnetic reversals. The other major motions observed are subduction on the New Britain Trench, seafloor spreading across the Bismarck Sea Seismic Lineation, convergence across the Ramu-Markham Fault and left-lateral strike slip across the Papuan Peninsula. These motions are consistent with a 8.2° Myr-1 clockwise rotation of the South Bismarck Plate about a pole in the Huon Gulf and a rotation of the Woodlark Plate away from the Australian Plate. Second order deformation may also be occurring; in particular, Manus Island and northern New Ireland may be moving northward relative to the Pacific Plate at ˜5-8 mm yr-1 (significant at the 95% but not at the 99% confidence level) which may suggest the existence of a North Bismarck Plate.

  18. Bipolar battery plate

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor)

    1987-01-01

    A liquid-impermeable plate (10) having through-plate conductivity with essentially zero resistance comprises an insulator sheet (12) having a series of spaced perforations (14) each of which contains a metal element (16) sealingly received into the perforation (14). A low-cost plate can readily be manufactured by punching a thermoplastic sheet (40) such as polypropylene with a punching tool (52), filling the apertures with led spheres (63) having a diameter smaller than the holes (50) but larger than the thickness of the sheet, sweeping excess spheres (62) off the sheet with a doctor blade (60) and then pressing a heated platen (74) onto the sheet to swage the spheres into a cylindrical shape and melt the surrounding resin to form a liquid-impermeable collar (4) sealing the metal into the sheet.

  19. The San Andreas fault experiment. [gross tectonic plates relative velocity

    NASA Technical Reports Server (NTRS)

    Smith, D. E.; Vonbun, F. O.

    1973-01-01

    A plan was developed during 1971 to determine gross tectonic plate motions along the San Andreas Fault System in California. Knowledge of the gross motion along the total fault system is an essential component in the construction of realistic deformation models of fault regions. Such mathematical models will be used in the future for studies which will eventually lead to prediction of major earthquakes. The main purpose of the experiment described is the determination of the relative velocity of the North American and the Pacific Plates. This motion being so extremely small, cannot be measured directly but can be deduced from distance measurements between points on opposite sites of the plate boundary taken over a number of years.

  20. Reduced Plating Ignitron

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A (Inventor); Pearson, J Boise (Inventor)

    2014-01-01

    An ignitron apparatus has an airtight tubular housing having a first sealed end and a second sealed end. An anode is connected at the first sealed end, projecting into the housing, and a recess at the second sealed and forms a well which contains a quantity of liquid gallium or gallium alloy making up the cathode. An ignitor projects through the liquid metal and into the housing. The inner surface of the housing includes at least one plating-reduction structure to prevent electrical shorting of the apparatus caused by plating of the liquid metal.

  1. Nuclear reactor alignment plate configuration

    DOEpatents

    Altman, David A; Forsyth, David R; Smith, Richard E; Singleton, Norman R

    2014-01-28

    An alignment plate that is attached to a core barrel of a pressurized water reactor and fits within slots within a top plate of a lower core shroud and upper core plate to maintain lateral alignment of the reactor internals. The alignment plate is connected to the core barrel through two vertically-spaced dowel pins that extend from the outside surface of the core barrel through a reinforcement pad and into corresponding holes in the alignment plate. Additionally, threaded fasteners are inserted around the perimeter of the reinforcement pad and into the alignment plate to further secure the alignment plate to the core barrel. A fillet weld also is deposited around the perimeter of the reinforcement pad. To accomodate thermal growth between the alignment plate and the core barrel, a gap is left above, below and at both sides of one of the dowel pins in the alignment plate holes through with the dowel pins pass.

  2. ILLUSTRATIONS. PLATES-PART !.

    E-print Network

    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208 A M~THOD OF LOBSTER CULTURE: Plate VII. (r) General view of houseboat and floats. (2) Inside. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 VIII. (3) Floats from outer corner looking forward. (4) One of the outside floats, car raised. Specimen of rock from sponge beds off Anclote Key, Florida. . . . . . . . . . . . 403 XXIX. (I) Diving boat

  3. INL HIP Plate Fabrication

    SciTech Connect

    B. H. Park; C. R. Clark; J. F. Jue

    2010-02-01

    This document outlines the process used to bond monolithic fuel plates by Hot Isostatic Pressing (HIP). This method was developed at Idaho National Laboratory (INL) for the Reduced Enrichment for Research and Test Reactors (RERTR) program. These foils have been used in a number of irradiation experiments in support of the United States Global Threat Reduction Initiative (GTRI) program.

  4. The Plate Tectonics Project

    ERIC Educational Resources Information Center

    Hein, Annamae J.

    2011-01-01

    The Plate Tectonics Project is a multiday, inquiry-based unit that facilitates students as self-motivated learners. Reliable Web sites are offered to assist with lessons, and a summative rubric is used to facilitate the holistic nature of the project. After each topic (parts of the Earth, continental drift, etc.) is covered, the students will…

  5. Unitary plate electrode

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor); Clough, Thomas J. (Inventor); Josefowicz, Jack Y. (Inventor); Sibert, John W. (Inventor)

    1985-01-01

    The unitary electrode (10) comprises a porous sheet (12) of fiberglass the strands (14) of which contain a coating (16) of conductive tin oxide. The lower portion of the sheet contains a layer (18) of resin and the upper layer (20) contains lead dioxide forming a positive active electrode on an electrolyte-impervious layer. The strands (14) form a continuous conduction path through both layers (16, 18). Tin oxide is prevented from reduction by coating the surface of the plate facing the negative electrode with a conductive, impervious layer resistant to reduction such as a thin film (130) of lead or graphite filled resin adhered to the plate with a layer (31) of conductive adhesive. The plate (10) can be formed by casting a molten resin from kettle (60) onto a sheet of glass wool (56) overlying a sheet of lead foil and then applying positive active paste from hopper (64) into the upper layer (68). The plate can also be formed by passing an assembly of a sheet ( 80) of resin, a sheet (86) of sintered glass and a sheet (90) of lead between the nip (92) of heated rollers (93, 95) and then filling lead oxide into the pores (116) of the upper layer (118).

  6. Relation between subduction megathrust earthquakes, sediment thickness at trench, and plate coupling

    NASA Astrophysics Data System (ADS)

    Heuret, A.; Conrad, C. P.; Funiciello, F.; Lallemand, S.

    2011-12-01

    Extreme seismic events (Mw 8.5 and higher) are uniformly characterized by trench-parallel rupture lengths longer than about 250 km, whereas downdip rupture width ranges from less than 70 km (e.g., Central Aleutians) to more than 200 km (e.g., Andaman-Sumatra). The ability of rupture to propagate in the trench-parallel direction thus appears to play a fundamental role in determining the potential magnitude that an earthquake can achieve for a given subduction zone. The rupture length may be influenced by the nature of the plate interface and the normal stresses applied to the plate interface (plate coupling). The nature of the plate interface is potentially modified by sediment subduction. Subduction of a thick section of trench sediment constructs a laterally homogenous layer between upper and lower plates that smoothes subducted sea-floor relief and strength-coupling asperities (Ruff, 1989). Such a homogeneous interface running parallel to the subduction zone tends to favor long trench-parallel propagation of rupture, and thus large earthquake magnitudes. Compressive normal stresses applied along the plate interface may also tune the earthquake magnitude potential (Ruff & Kanamori, 1980). This plate coupling across the subducting interface can be indirectly estimated by Upper Plate Strain analysis, by using the back-arc as a strain sensor from which we can infer the back-arc stress state. Compressive back-arcs indicate that large stresses are transmitted across the plate interface whereas extensional settings indicate weak plate coupling. Here we present the results of a study funded by the European Science Foundation - EURYI project titled "Convergent margin and seismogenesis". Maximal earthquake magnitude, sediment thickness at the trench and Upper Plate Strain are characterized for worldwide subduction zones in order to test how plate coupling and sediment thickness combine to explain the occurrence of mega-events at the subduction interface. Subduction zones are described through an initial set of 505 transects, systematically extracted each 1° of trench, and merged into 62 subduction segments of homogeneous seismogenetic conditions. Maximal earthquake magnitude has been estimated by combining instrumental and historical seismicity. Trench sediment thickness has been constrained for 48 subduction segments; based on a compilation of 165 different seismic-reflection lines (33% of the initial set of transects).

  7. Deep earthquakes in the southwest Pacific: A tectonic interpretation

    SciTech Connect

    Hamburger, M.W.; Isacks, B.L.

    1987-12-10

    This paper examines the spatial distribution deep earthquakes in the Tonga-Fiji-New Hebrides region of the southwest Pacific. Our interpretation emphasizes the complex Cenozoic tectonics of the Pacific/Indo-Australian plate boundary as a primary control on the distribution and deformation of subducted lithosphere. Most deep earthquakes in the interarc region are associated with the contorted Pacific plate lithosphere subducted at the Tonga Trench. However, anomalous groups of deep earthquakes located west of the Tonga zone are unrelated to the present plate configuration. Tectonic reconstructions of the region to 8 m.y. B.P. provide circumstantial evidence that (1) the anomalous events west of the Tonga zone occur in two pieces of detached lithosphere, subducted at the Vitiaz and proto-New Hebrides trenches during the late Miocene, (2) the flattening of the inclined seismic zone in northernmost Tonga is related to the rapid opening of the Lau Basin since 4 m.y. B.P., and (3) the sharp westward curvature of the Tonga seismic zone in this area coincides with a preexisting bend in the late Miocene Vitiaz arc. The sharpness of its present curvature appears to be secondary effect of shear flow in the lower mantle and compression between detached (Vitiaz) and attached (Tonga) lithosphere. Thus much of the contortion of the subducted lithosphere beneath Tonga-Fiji may be produced by local tectonic interactions, rather than collision of the slab with an impenetrable boundary in the midmantle. copyright American Geophysical Union 1987

  8. Plate Motions, Regional Deformation, and Time-Variation of Plate Motions

    NASA Technical Reports Server (NTRS)

    Gordon, R. G.

    1998-01-01

    The significant results obtained with support of this grant include the following: (1) Using VLBI data in combination with other geodetical, geophysical, and geological data to bound the present rotation of the Colorado Plateau, and to evaluate to its implications for the kinematics and seismogenic potential of the western half of the conterminous U.S. (2) Determining realistic estimates of uncertainties for VLBI data and then applying the data and uncertainties to obtain an upper bound on the integral of deformation within the "stable interior" of the North American and other plates and thus to place an upper bound on the seismogenic potential within these regions. (3) Combining VLBI data with other geodetic, geophysical, and geologic data to estimate the motion of coastal California in a frame of reference attached to the Sierra Nevada-Great Valley microplate. This analysis has provided new insights into the kinematic boundary conditions that may control or at least strongly influence the locations of asperities that rupture in great earthquakes along the San Andreas transform system. (4) Determining a global tectonic model from VLBI geodetic data that combines the estimation of plate angular velocities with individual site linear velocities where tectonically appropriate. and (5) Investigation of the some of the outstanding problems defined by the work leading to global plate motion model NUVEL-1. These problems, such as the motion between the Pacific and North American plates and between west Africa and east Africa, are focused on regions where the seismogenic potential may be greater than implied by published plate tectonic models.

  9. Subduction zone plate bending earthquakes and implications for the hydration of the downgoing plate

    NASA Astrophysics Data System (ADS)

    Emry, E. L.; Wiens, D. A.

    2011-12-01

    The greatest uncertainty in the amount of water input into the Earth at subduction zones results from poor constraints on the degree and depth extent of mantle serpentinization in the downgoing slab. The maximum depth of serpentinization is thought to be partly controlled by the maximum depth of tensional earthquakes in the outer rise and trench and is expected to vary from subduction zone to subduction zone or even along-strike for a single subduction zone. We explore the maximum depth of extensional faulting on the incoming plate for various subduction zones in order to gain insight into the possible extent of slab serpentinization. We relocate trench events at island arc subduction zones using hypocentroidal decomposition to determine which earthquakes occurred within the incoming plate. For earthquakes with Mw ~5.5+, we determine accurate depths and refine the CMT focal mechanism by inverting teleseismic P and SH waveforms. Results from the Mariana outer rise indicate that extensional earthquakes occur in the Pacific plate at depths ranging from 10-20 km beneath the top of the crust, with the character of trench seismicity changing significantly between the northern and southern portions of the subduction zone. In comparision, results from the Aleutian subduction zone show extensional trench earthquakes occurring from 5-30 km below the surface of the subducting slab. Compressional incoming plate earthquakes occur only near the Alaskan Peninsula, possibly due to stronger coupling between the slab and overriding plate in this region. Further results from oceanic arc subduction zones will be presented and differences between subduction zones as well as along-strike differences in the character of trench seismicity will be highlighted. If the presence of extensional faulting indicates subducting lithosphere hydration, then we expect that as much as the top 30 km of the slab may be hydrated and that the degree of slab serpentinization may vary significantly between subduction zones, potentially affecting arc geochemistry, intermediate depth seismicity, and the subduction zone water budget.

  10. Development of transtensional and transpressive plate boundaries due to noncircular (cycloid) relative plate motion

    SciTech Connect

    Cronin, V.S. )

    1990-05-01

    The trace of a transform fault commonly is assumed to be circular and concentric with the finite relative motion of the plates adjacent to the fault. These assumptions have led to controversy as the transform fault label has been applied to the San Andreas fault in California because the San Andreas fault is neither circular nor concentric with the motion of the Pacific plate relative to the North American plate. The assumption of circular relative plate motion over a finite time interval is not generally valid. When finite relative plate motion is not circular, the length and orientation of a transform fault must change through time. The length and orientation of ridge-ridge transform faults in oceanic crust evolve through the migration, propagation, and abandonment of ridge segments. Transform faults that bound continental crust evolve differently than do transform faults along mid-ocean ridges because continental transform faults typically do not have ridges at both ends and because of the rheological differences between oceanic and continental crust. Along continent-continent transform faults in which the initial displacement is entirely strike slip, later displacements will be progressively more divergent or convergent (i.e., transtensive or transpressive). Transtension can result in the development of deep basins with high heat flow. Transpression can result in folding, reverse faulting, and decoupling of the crust from its lower crustal or mantle lithosphere in the region adjacent to the transform fault. Regardless of whether the transform boundary becomes transtensional or transpressional, the boundary evolves from a discrete transform fault to a broader, structurally complex accommodation zone (sensu lato).

  11. Transition on the Geometry of the Cocos Plate in Central-Southern Mexico.

    NASA Astrophysics Data System (ADS)

    Rodríguez-Domínguez, M. Á.; Perez-Campos, X.; Valencia-Cabrera, D.; Clayton, R. W.; Cordoba-Montiel, F.; Valdes-Gonzales, C. M.; Brudzinski, M. R.; Cabral-Cano, E.; Arciniega-Ceballos, A.

    2014-12-01

    The tectonic setting, produced by the interaction between the Cocos and North American plates, follows complex geometries along the Pacific coast. Previous studies in central Mexico showed that the slab dips nearly horizontally before steeply subducting into the continental mantle; in contrast, in southern Mexico, the slabs dips under the continental plate at a constant angle. Receiver functions from four seismic networks: GECO (Geometry of Cocos), SSN (Servicio Sismológico Nacional), OxNet (Oaxaca Network) and UV (Universidad Veracruzana) are used to study the crustal structure underneath the stations, and image the subducting Cocos plate in order to define the geometry and the transition angle in central-southern Mexico.

  12. Deck view, west approach; former Western Pacific (now Union Pacific) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Deck view, west approach; former Western Pacific (now Union Pacific) Railroad at left; wind turbine generators atop hill in background; view to northeast; 90mm lens - Carroll Overhead Bridge, Altamont Pass Road, Livermore, Alameda County, CA

  13. Palaeotectonic implications of increased late Eocene-early Oligocene volcanism from South Pacific DSDP sites

    USGS Publications Warehouse

    Kennett, J.P.; Von Der Borch, C.; Baker, P.A.; Barton, C.E.; Boersma, A.; Cauler, J.P.; Dudley, W.C., Jr.; Gardner, J.V.; Jenkins, D.G.; Lohman, W.H.; Martini, E.; Merrill, R.B.; Morin, R.; Nelson, Campbell S.; Robert, C.; Srinivasan, M.S.; Stein, R.; Takeuchi, A.; Murphy, M.G.

    1985-01-01

    Late Eocene-early Oligocene (42-35 Myr) sediments cored at two DSDP sites in the south-west Pacific contain evidence of a pronounced increase in local volcanic activity, particularly in close association with the Eocene-Oligocene boundary. This pulse of volcanism is coeval with that in New Zealand and resulted from the development of an Indo- Australian / Pacific Plate boundary through the region during the late Eocene. The late Eocene / earliest Oligocene was marked by widespread volcanism and tectonism throughout the Pacific and elsewhere, and by one of the most important episodes of Cenozoic climatic cooling. ?? 1985 Nature Publishing Group.

  14. Soft Interfaces

    NASA Astrophysics Data System (ADS)

    Gilles de Gennes, Pierre; Edwards, Introduction By Sam

    1997-04-01

    Paul Adrien Maurice Dirac, one of the greatest physicists of the twentieth century, died in 1984. Dirac's college, St. John's of Cambridge, generously endowed annual lectures to be held at Cambridge University in his memory. This volume contains a much expanded version of the 1994 Dirac Lecture by Nobel Laureate Pierre Gilles de Gennes. The book presents an impressionistic tour of the physics of soft interfaces. Full of insight and interesting asides, it not only provides an accessible introduction to this topic, but also lays down many markers and signposts that will be of interest to researchers in physics or chemistry. Features discussions of wetting and dewetting, the dynamics of different types of interface and adhesion and polymer/polymer welding.

  15. The Microstructure of Rolled Plates from Cast Billets of U-10Mo Alloys

    SciTech Connect

    Nyberg, Eric A.; Joshi, Vineet V.; Burkes, Douglas; Lavender, Curt A.

    2015-03-01

    This report covers the examination of 13 samples of rolled plates from three separate castings of uranium, alloyed with 10 wt% molybdenum (U-10Mo) which were sent from the Y-12 National Security Complex (Y12) to the Pacific Northwest National Laboratory (PNNL).

  16. Borehole Magnetic Field Simulation of Rotated Plates with Special Application for the Philippine Sea and Caroline Plates

    NASA Astrophysics Data System (ADS)

    Lee, S. M.; Kim, J.; Kim, C.; Virgil, C.; Neuhaus, M.; Hoerdt, A.

    2014-12-01

    The rotation of tectonic plates and basins is not uncommon in the Western Pacific. However, determining the exact amount of rotation over geological time can be quite challenging, especially for the Philippine Sea and Caroline Plates, because paleomagnetic measurements are rare and even if they exist come from sites near the plate boundary which may have suffered local tectonic deformations. Although it is generally thought that the Philippine Sea Plate rotated 90° clockwise during the last 55 Ma and that Caroline Plate likewise began to rotate soon after its formation around 32 Ma, there is no direct evidence for such arguments. While the recent IODP drilling (Leg 351) of the Amami-Sankaku Basin in the northern tip of the West Philippine Basin promises to provide an opportunity to estimate the rotation of the Philippine Sea Plate, in practice, the collection and subsequent reduction of borehole magnetic field data can be quite complicated. Moreover, if the magnetization intensity is low, which is the case for sediments, it is difficult to assess the outcome of magnetic field investigations. Hence, it is important to have the capability to compare the observation with model simulation readily. In this paper, we present magnetic field simulations within the borehole using the analytical methods outlined by Bosum and others (1988) which assumes a circular borehole within uniformly magnetized strata layers and Gallet and Courtilot (1989) which can accommodate inclined layers. The methods are applied to the Philippine Sea Plate and Caroline Plate using geological parameters whose values are derived from previous kinematic models. The results of such modeling can be quite useful and important in planning additional borehole magnetic surveys for the future as well.

  17. Rupture characterizations of the 2011 Mw 9.1 off the Pacific coast of Tohoku earthquake and its March 9th Mw 7.4 foreshock constrained by an unprecedented dataset for subduction earthquakes

    NASA Astrophysics Data System (ADS)

    Shao, G.; Ji, C.

    2011-12-01

    The kinematic slip history of the 2011 Mw 9.1 off the Pacific coast of Tohoku earthquake and its March 9th 7.4 foreshock are constrained by jointly inverting teleseismic broadband body waves, long period surface waves, local strong motion data, and GPS observations. The unique GPS data at five ocean bottom stations [Sato et al., 2011] are also included in the mainshock study. The mainshock and foreshock hypocenters are relocated using a double-difference approach and teleseismic P waves. The fault geometry inferred from a local seismic velocity profile [Miura et al., 2005] has been further perturbed to reconcile different datasets. Our results show that the closely located foreshock and mainshock, only 35 km away from each other, have experienced different rupture histories. The foreshock rupture initiated at a depth of 14 km and then broke an elliptical shape asperity in downdip, elongating for ~ 90 km in the west-northwest direction in the map view. It released a total seismic moment of 1.6x1020 Nm, which is characterized by a relatively small average slip of 1 m and low average stress drop of 0.9 MPa on the fault plane. The fault rupture had a normal rupture velocity up to 3.1 km/s. Meanwhile, the Tohoku mainshock rupture, which occurred 51 hours later, initiated slowly at a depth of 23 km. It first propagated in downdip and bilaterally along the subduction interface for about 40 s. It then broke a large near trench asperity in the up-dip direction that produced a peak slip up to 63.5 m. The mainshock has a total seismic moment of 5.4x1022 Nm. It has an unexpectedly large average slip of 21.4 m and a much high average stress drop of 9 MPa. The mainshock has re-ruptured the slip zone of the foreshock in a velocity of 1-1.5 km/s and produced a much larger slip of 20-30 m. By comparing the fault slip distribution with background seismicity, local bathymetric relief and velocity anomaly along the subducting Pacific Plate interface, we suggest that the foreshock might only have ruptured a relatively weaker patch of plate interface associated with a subducting seamount. However, the mainshock ruptured the stronger part on the plate interface and released the accumulated deficit slip in the foreshock slip region.

  18. Fluid dynamics of rivulet flow between plates

    NASA Astrophysics Data System (ADS)

    Drenckhan, W.; Ritacco, H.; Saint-Jalmes, A.; Saugey, A.; McGuinness, P.; van der Net, A.; Langevin, D.; Weaire, D.

    2007-10-01

    We present computational and experimental investigations into the fluid dynamics of a narrow stream of surfactant solutions, which descends under gravity between two narrowly spaced, vertical glass plates. Such a "rivulet" is bounded by two liquid/solid and two mobile liquid/gas interfaces, posing fluid dynamic problems of direct relevance to local fluid flow in liquid foams and recently reported meandering phenomena. The rivulet presents a system in which the coupling between the bulk flow and the rheological properties of the gas/liquid interface can be systematically investigated. In particular, it carries the promise of providing an alternative measuring technique for interfacial shear viscosities. We present finite element simulations in conjunction with experiments in order to describe the relationship between the rivulet geometry, the flow field, and the interfacial shear viscosities. We also report on the role of the boundary condition between the liquid-carrying channels (surface Plateau borders) and the thin soap film, which spans the two plates at low flow rates.

  19. The 4th volcanic zone, petit-spot, in response to plate flexure (Invited)

    NASA Astrophysics Data System (ADS)

    Hirano, N.

    2009-12-01

    No present-day volcanic activity had been documented on such a cool, thick and old Cretaceous lithosphere before, while volcanoes of the Earth are generally classified into the next three settings in the traditional plate tectonics theory; divergence plate-margins (e.g. mid-ocean ridges), plate-subduction zones (e.g. island arcs) and hotspots (e.g. intra-plate oceanic islands). A zero aged (0.05-1.03 Ma) and some young volcanoes (1.8, 4.2, 6.0 and 8.5 Ma) of the strongly alkaline magma were discovered on the abyssal plain of the Early Cretaceous (135 Ma) Pacific Plate. An outer-rise forms during subduction when old and cold lithosphere bends so that it can sink into the interior of the Earth at the trenches. This flexing is mostly an elastic behavior, but it may also cause brittle fracturing of the downgoing slabs. One of the mechanisms by which magma reaches the Earth's surface is ascent along brittle fractures that develop where plates flex due to subduction, thereby forming a swarm of small knolls termed "petit-spots" as the 4th volcanic zone on the Earth. Such lavas are enriched in highly incompatible elements, suggesting an origin via partial melting of the asthenosphere. The widespread occurrence of this process is indicated by the discovery of petit-spots across broad regions of the NW Pacific plate and near the Tonga and Chile Trenches.

  20. Low Pacific secular variation

    NASA Astrophysics Data System (ADS)

    Gubbins, David; Gibbons, Steven J.

    The historical record shows that secular variation at Hawaii is limited to a few degrees in the last 400 years, whereas in the Atlantic hemisphere it often exceeds 30°. Paleomagnetic measurements from Hawaii show virtually no change in declination during the last 5 kyr and only a slow, millenium-scale inclination change of less than 20°. The usual directional scatter analysis of paleomagnetic data cannot discriminate between the two time scales. The disparity of time scales and difference in activity suggest different physical mechanisms for secular variation in the two hemispheres. This could arise from thermal core-mantle interaction. Seismic models of the lower mantle give a pattern of lateral variations that is nearly symmetric about the Pacific rim: two slow regions centered beneath the Pacific and Atlantic separated by a fast ring below the Pacific rim. These seismic anomalies are thought to be caused mostly by temperature variations in the bottom 200 km of the mantle. It is difficult to see how such a symmetric pattern could lead to long-term hemispheric differences. We show here a convection solution in a rapidly rotating sphere with heat flux on the outer boundary determined from a seismic model. The convection is suppressed beneath the Pacific but the usual drifting convection (Busse) rolls remain beneath the Atlantic. This mode of periodic convection arises because the Pacific hot region extends east-west and is much larger than a single convection roll, whereas the Atlantic hot region is elongated north-south and is about the same east-west size as a convection roll. This could explain the absence of normal, century-long secular variation in the Pacific: hot mantle suppresses short wavelength phenomena at the century time scale but not the longer wavelengths at the millenium time scale.

  1. Impedance of infinite Kirchhoff and Mindlin plates with a rigid circular massless plug.

    PubMed

    Zapfe, Jeffrey A; Moore, James A

    2012-05-01

    Point force impedance expressions have been previously developed for infinite Kirchhoff and Mindlin plates. The present work develops impedance expressions for the more general case of an infinite plate with a circular, massless, rigid plug using both Kirchhoff and Mindlin plate theories. The models have been developed to analyze vibration propagation in buildings. The plate with the rigid plug provides a more reasonable model of the kinematic constraint at the column/floor interface. The models are used to investigate the potential benefits of using thick floors to block the transmission of structure-borne vibration in buildings. PMID:22559358

  2. North American plate dynamics

    NASA Technical Reports Server (NTRS)

    Richardson, Randall M.; Reding, Lynn M.

    1991-01-01

    Deformation within the North American plate in response to various tectonic processes is modeled using an elastic finite element analysis. The tectonic processes considered in the modeling include ridge forces associated with the normal thermal evolution of oceanic lithosphere, shear and normal stresses transmitted across transforms, normal stresses transmitted across convergent boundaries, stresses due to horizontal density contrasts within the continent, and shear tractions applied along the base of the plate. Model stresses are calculated with respect to a lithostatic reference stress state. Shear stresses transmitted across transform boundaries along the San Andreas and Caribbean are small, of the order of 5-10 MPa. Also, compressive stresses of the order of 5-10 MPa transmitted across the major transforms improve the fit to the data. Compressive stresses across convergent margins along the Aleutians and the Middle America trench are important.

  3. Bipolar battery plate

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor)

    1985-01-01

    A liquid-impermeable plate (10) having throughplate conductivity with essentially zero resistance comprises an insulator sheet (12) having a series of spaced perforations (14) each of which contains a metal element (16) sealingly received into the perforation (14). A low-cost plate can readily be manufactured by punching a thermoplastic sheet (40) such as polypropylene with a punching tool (52), filling the apertures with lead spheres (63) having a diameter smaller than the holes (50) but larger than the thickness of the sheet, sweeping excess spheres (62) off the sheet with a doctor blade (60) and then pressing a heated platen (74) onto the sheet to swage the spheres into a cylindrical shape and melt the surrounding resin to form a liquid-impermeable collar (4) sealing the metal into the sheet.

  4. Microchannel plate streak camera

    DOEpatents

    Wang, C.L.

    1984-09-28

    An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (uv to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 keV x-rays.

  5. Microchannel plate streak camera

    DOEpatents

    Wang, Ching L. (Livermore, CA)

    1989-01-01

    An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 KeV x-rays.

  6. Microchannel plate streak camera

    DOEpatents

    Wang, C.L.

    1989-03-21

    An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras is disclosed. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1,000 KeV x-rays. 3 figs.

  7. Franciscan complex calera limestones: Accreted remnants of farallon plate oceanic plateaus

    USGS Publications Warehouse

    Tarduno, J.A.; McWilliams, M.; Debiche, M.G.; Sliter, W.V.; Blake, M.C.

    1985-01-01

    The Calera Limestone, part of the Franciscan Complex of northern California, may have formed in a palaeoenvironment similar to Hess and Shatsky Rises of the present north-west Pacific1. We report here new palaeomagnetic results, palaeontological data and recent plate-motion models that reinforce this assertion. The Calera Limestone may have formed on Farallon Plate plateaus, north of the Pacific-Farallon spreading centre as a counterpart to Hess or Shatsky Rises. In one model2, the plateaus were formed by hotspots close to the Farallon_Pacific ridge axis. On accretion to North America, plateau dissection in the late Cretaceous to Eocene (50-70 Myr) could explain the occurrence of large volumes of pillow basalt and exotic blocks of limestone in the Franciscan Complex. Partial subduction of the plateaus could have contributed to Laramide (70-40 Myr) compressional events3. ?? 1985 Nature Publishing Group.

  8. Plated wire memory subsystem

    NASA Technical Reports Server (NTRS)

    Reynolds, L.; Tweed, H.

    1972-01-01

    The work performed entailed the design, development, construction and testing of a 4000 word by 18 bit random access, NDRO plated wire memory for use in conjunction with a spacecraft imput/output unit and central processing unit. The primary design parameters, in order of importance, were high reliability, low power, volume and weight. A single memory unit, referred to as a qualification model, was delivered.

  9. Plate motion and deformation

    SciTech Connect

    Minster, B.; Prescott, W.; Royden, L.

    1991-02-01

    Our goal is to understand the motions of the plates, the deformation along their boundaries and within their interiors, and the processes that control these tectonic phenomena. In the broadest terms, we must strive to understand the relationships of regional and local deformation to flow in the upper mantle and the rheological, thermal and density structure of the lithosphere. The essential data sets which we require to reach our goal consist of maps of current strain rates at the earth's surface and the distribution of integrated deformation through time as recorded in the geologic record. Our success will depend on the effective synthesis of crustal kinematics with a variety of other geological and geophysical data, within a quantitative theoretical framework describing processes in the earth's interior. Only in this way can we relate the snapshot of current motions and earth structure provided by geodetic and geophysical data with long-term processes operating on the time scales relevant to most geological processes. The wide-spread use of space-based techniques, coupled with traditional geological and geophysical data, promises a revolution in our understanding of the kinematics and dynamics of plate motions over a broad range of spatial and temporal scales and in a variety of geologic settings. The space-based techniques that best address problems in plate motion and deformation are precise space-geodetic positioning -- on land and on the seafloor -- and satellite acquisition of detailed altimetric and remote sensing data in oceanic and continental areas. The overall science objectives for the NASA Solid Earth Science plan for the 1990's, are to Understand the motion and deformation of the lithosphere within and across plate boundaries'', and to understand the dynamics of the mantle, the structure and evolution of the lithosphere, and the landforms that result from local and regional deformation. 57 refs., 7 figs., 2 tabs.

  10. Elastic plate spallation

    NASA Technical Reports Server (NTRS)

    Oline, L.; Medaglia, J.

    1972-01-01

    The dynamic finite element method was used to investigate elastic stress waves in a plate. Strain displacement and stress strain relations are discussed along with the stiffness and mass matrix. The results of studying point load, and distributed load over small, intermediate, and large radii are reported. The derivation of finite element matrices, and the derivation of lumped and consistent matrices for one dimensional problems with Laplace transfer solutions are included. The computer program JMMSPALL is also included.

  11. Plate tectonics and crustal deformation around the Japanese Islands

    NASA Technical Reports Server (NTRS)

    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.

  12. Fiji in the South Pacific.

    ERIC Educational Resources Information Center

    Scott, Rosalind; Semaan, Leslie

    This text introduces Fiji and other island nations located in the Pacific, the world's largest ocean. Cut off from the world by vast expanses of water, these people developed a unique culture. Contents include: Teacher Overview, Geography of the South Pacific Islands, History of the South Pacific, Fiji, Traditional Village Life, Yaquna Ceremony,…

  13. Symmetries in laminated composite plates

    NASA Technical Reports Server (NTRS)

    Noor, A. K.

    1976-01-01

    The different types of symmetry exhibited by laminated anisotropic fibrous composite plates are identified and contrasted with the symmetries of isotropic and homogeneous orthotropic plates. The effects of variations in the fiber orientation and the stacking sequence of the layers on the symmetries exhibited by composite plates are discussed. Both the linear and geometrically nonlinear responses of the plates are considered. A simple procedure is presented for exploiting the symmetries in the finite element analysis. Examples are given of square, skew and polygonal plates where use of symmetry concepts can significantly reduce the scope and cost of analysis.

  14. Coevolution of the Pacific salmon and Pacific Rim topography

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.

    2000-12-01

    The late Cenozoic radiation of the Pacific salmon and trout (Oncorhynchus spp.) resulted in five species that are widely distributed in western North America and occupy distinct parts of river networks. The dramatic radiation of the Pacific salmon contrasts with the history of the Atlantic salmon, which have evolved little since the divergence of Oncorhynchus. Conventional hypotheses for the radiation of the Pacific salmon stress geographic isolation due to Pleistocene glaciations, but paleontological evidence dates their speciation to the middle Miocene to early Pliocene. Tertiary marine cooling may have spurred the development of anadromy in salmon and other fish, but does not readily explain the different evolutionary trajectories for the Pacific and Atlantic salmon. The timing of Pacific salmon speciation corresponds to significant physiographic changes around the Pacific Rim, suggesting that increased topographic diversity due to an active tectonic regime contributed to the evolution of the Pacific salmon.

  15. Forest Service Pacific Southwest

    E-print Network

    Forest Service Pacific Southwest Forest and Range Experiment Station Research Paper P8W-182 Release: PHILIP M. McDONALD is a research forester assigned to the Station's research unit studying, what would be the tradeoffs between stem caliper growth of Douglas-fir seedlings and treatment costs

  16. INTERNATIONAL PACIFIC RESEARCH CENTER

    E-print Network

    Wang, Yuqing

    Pacific Research Center Design by: Susan Yamamoto Printed by: Hagadone Printing Company Photo: Waikiki. Our understanding of air­sea interactions has advanced markedly, especially our knowledge of how sea month in advance. Another approach we have taken, the use of a cou- pled air­sea model, also suggests

  17. The Pacific Rim.

    ERIC Educational Resources Information Center

    Thomas, Paul F., Ed.

    1988-01-01

    The articles in this special edition were compiled to provide information to Canadian social studies teachers about Pacific Rim countries. Section 1, entitled "The Big Picture and Future Interests," contains: (1) "Social Studies for the 21st Century" (J. Tucker); (2) "Culture and Communication: A Perspective on Asian Studies for Tomorrow's…

  18. Fuel cell end plate structure

    DOEpatents

    Guthrie, Robin J. (East Hartford, CT); Katz, Murray (Newington, CT); Schroll, Craig R. (Glastonbury, CT)

    1991-04-23

    The end plates (16) of a fuel cell stack (12) are formed of a thin membrane. Pressure plates (20) exert compressive load through insulation layers (22, 26) to the membrane. Electrical contact between the end plates (16) and electrodes (50, 58) is maintained without deleterious making and breaking of electrical contacts during thermal transients. The thin end plate (16) under compressive load will not distort with a temperature difference across its thickness. Pressure plate (20) experiences a low thermal transient because it is insulated from the cell. The impact on the end plate of any slight deflection created in the pressure plate by temperature difference is minimized by the resilient pressure pad, in the form of insulation, therebetween.

  19. Past Mantle Dynamics Revealed by Net Characteristics of Surface Plate Motions

    NASA Astrophysics Data System (ADS)

    Conrad, C. P.; Steinberger, B. M.; Torsvik, T. H.

    2012-12-01

    Although convection within Earth's mantle ultimately drives much of Earth's geological evolution, constraints on the history of mantle flow are difficult to obtain because the geometries and magnitudes of past driving forces are difficult to estimate. However, plate tectonic reconstructions, which are becoming increasing well-constrained, should contain information about the underlying mantle flow that drove plate motions in the past. Although the motions of individual plates can be affected by the specific details of individual plate forces, which can vary significantly in both space and time, long-wavelength forcings on plates may be reflected in patterns of plate motions occurring over length scales longer than those of individual plates. To test this, we measured the dipole and quadrupole moments of present-day plate motions and compared their orientations to the analogous moments of basal tractions exerted on plates in a mantle flow model driven by tomographically-inferred mantle density heterogeneity. We found that both plate motions and net tractions converged in a net sense toward a dipole located in Asia. Similarly, both vector fields indicate quadrupole divergence in both Africa and the equatorial Pacific and quadruple convergence in southeast Asia and eastern South America. These similarities in dipole and quadrupole orientations indicate that the net characteristics of surface plate motions are reflective of global mantle flow patterns. To constrain temporal variations in mantle flow patterns, we measured the dipole and quadrupole moments of surface plate tectonics as a function of time for three different plate tectonic reconstructions dating as far back as 250 Ma. In all three, we found remarkable stability in the orientations of both the dipole moment and the divergence component of the quadrupole moment, indicating that the locations of net upwelling flow in the Earth's mantle have remained relatively fixed, at least throughout the Cenozoic and Mesozoic.

  20. Relating rapid plate-motion variations to plate-boundary forces in global coupled models of the mantle/lithosphere system: Effects of topography and friction (Invited)

    NASA Astrophysics Data System (ADS)

    Bunge, H.; Iaffaldano, G.

    2009-12-01

    Constraints on the plate tectonic force balance are fundamentally important but difficult to obtain, because mantle related driving forces and resisting plate boundary forces cannot easily be seperated. Here we compare the record of past plate motions with present-day plate motion models derived from space geodetic techniques which reveals a number of short-term variations in global plate velocities over the past 10 m.y. Such variations are a powerful probe into the nature and magnitude of plate boundary forces, because they are unlikely to originate from changes in mantle buoyancy forces which evolve on longer time scales. We exploit the constraints of the velocity record using a novel coupled modeling approach where global neo-tectonic simulations are combined with high-resolution mantle circulation models to arrive at simple global budgets of mantle, lithosphere and plate boundary forces. We focus on three plate boundary systems along the Nazca/South America plate margin, the Aleutian trench and the India/Australia plate boundary to show that gravitational spreading from high topography in the Andes and Tibet contributes substantially to the global plate tectonic force balance and that this contribution is sufficient to explain some 35% of recent velocity changes over the Earth’s surface, including the observed 30% convergence reduction between the Nazca/South America plates. Our models make a number of specific predictions such as significant lateral variations in plate coupling forces along a given margin revealed by trench parallel gravity and bathymetry anomalies and the occurrence of large earthquakes, as well as differences by as much as a factor of five from margin to margin. They also support the notion of a relatively young plate boundary separating the India and Australia plates, which has been postulated earlier. Importantly, we find that the modeled Nazca/South America convergence reduction explains recent spreading rate variations in the South Atlantic and South Pacific, which points to the importance of far field effects on the adjacent continents in explaining the spreading record of oceanic basins. Our numerical results demonstrate (a) that detailed budgets of forces acting upon plates can be obtained and (b) support the notion of strong forcing along weak plate boundaries

  1. The Scotia Sea - no asthenosphere outlet from under the Pacific

    NASA Astrophysics Data System (ADS)

    Nerlich, R.; Clark, S. R.; Bunge, H.-P.

    2012-04-01

    The Scotia Sea, which is wedged in between the South American Plate to the north and Antarctic Plate to the south, holds a prominent position in geodynamics. As neither continental roots nor active subduction zones are present on its western boundary, it has been proposed to be one of the few potential asthenosphere outlets from under the shrinking Pacific into the growing Atlantic. Such asthenosphere flux on the other hand has been proposed to be required to achieve mass balance between the Pacific and Atlantic mantle reservoirs. Other suggested outlets are the Caribbean and the gap between Australia and Antarctica (the Australian-Antarctic discordance). With respect to the Scotia Sea, shear wave splitting and geochemical studies have previously tested these ideas, but they have led to equivocal results. In contrast to these studies, we present now a geodynamic approach to this issue. By reconstructing the plate kinematic history of the Scotia Sea, which is characterized by complex back-arc spreading processes active on a range of time scales, we calculate the residual (dynamically maintained) topography of the region by comparing present-day isostatically corrected topography with that predicted from our reconstructions. For this purpose, the derived oceanic age-grid from our reconstruction model is converted into the expected ocean basement depth based on a standard half-space cooling model. If asthenosphere flow exists at present-day, we expect to see a systematic trend in dynamic topography decreasing from west to east in response to a flow-related pressure gradient in the sublithospheric mantle. Our results do not indicate any systematic trend in dynamic topography, however, pointing to the absence of a present-day Pacific-to-Atlantic asthenosphere flux around the tip of South America via Drake Passage. We therefore conclude that the required material to achieve mass balance between the Pacific and Atlantic mantle domains must be supplied from elsewhere.

  2. Fractures, not Plumes, Have Controlled Major Seamount Volcanism in the Pacific over 170 Million Years

    NASA Astrophysics Data System (ADS)

    Natland, J. H.; Winterer, E. L.

    2003-12-01

    The distribution of guyots and atolls and large volcanic islands on the Pacific plate can be used to outline the likely connection between stresses acting on the plate and the gradual development of large, linear volcanic chains over the past 170 Ma. We construe three general periods with different stress regimes in the history of the Pacific plate. 1) During the Jurassic and Early Cretaceous, the Pacific plate was surrounded by ridge segments and there were no major stress alignments within it. Within-plate volcanism thus assumed the scattered arrangement for the condition of no tectonic stress (1), and the large Magellan and Wake seamount clusters formed. Near the eastern boundaries of the plate, complex and shifting patterns of ridge reorganization dictated formation of very long, splayed, near-axis ridges such as Horizon Guyot and Necker Ridge. 2) At about 90 Ma, the growing middle-aged Pacific plate achieved its first persistent stress regime with the formation of subduction boundaries along its western or northwestern margin. The plate was no longer static but began to move over the asthenosphere and into the mantle. Subduction boundaries and the overall direction of subduction are uncertain, but this imparted a general yet not fully stable component of tension across the plate, producing the NNW Gilbert-Marshall, Line and Emperor Seamount ridges, generally orthogonal to the overall direction of least principal stress. The Line Island seamount chain, being near ridge axes, sustained a variable stress regime. It thus has no age progression of rocks dated between 70-90 Ma (2), great width, and a dual orientations of ridges. 3) By 47 Ma, nearly half of the boundaries of the Pacific plate now were trenches spanning from the Aleutians to New Zealand. In addition, northward migration of the Indian plate and Australia caught a major portion of the westerly moving Pacific plate between the northeast corner of the Tonga Trench and the Aleutians. The plate could not shift laterally in response to whatever was occurring along its eastern spreading boundaries. A very consistent and strong stress regime therefore developed across the Pacific plate with a NNE direction of least principal stress. The change in stress orientation may have taken up to 10 million years, during an interval marked by little or no volcanic productivity at the western end of the Hawaiian chain. Since that time, the predominant alignment of both linear island chains and Puka Puka-type ridges, from the Kodiak-Bowie chain in the Gulf of Alaska to the Louisville Ridge south of the Antarctic convergence, has been orthogonal to this direction. Development of large-volume persistent chains and shorter small-volume chains indicates patterns of differential stress in the plate, variable fertility and geochemistry of the asthenosphere and/or shallow convective overturn of the asthenosphere rather than the action of mantle plumes of different sizes and depths of origin. Tapping of enriched mantle by widespread volcano clusters during the Mesozoic suggests the presence of a shallow asthenospheric source layer rather than multiple narrow conduits. (1) Hieronymus, C.F., and Bercovici, D. 2000. Earth Planet. Sci. Lett. 181, 539-554. (2) Davis, A.S., Gray, L.B., Clague, D.A., and Hein, J.R., 2002 Geochem. Geophys. Geosyst. 3: 10.1029/2001GC0000190, 1-28.

  3. Tethyan closure, Andean orogeny, and westward drift of the Pacific Basin Laurent Husson a,

    E-print Network

    Conrad, Clint

    , Rennes, France b Department of Earth and Planetary Science, Johns Hopkins University, Baltimore, Maryland, USA c Dipartimento di Scienze Geologiche, Universita Roma Tre, Rome, Italy A B S T R A C TA R T I C L the westward drift of the Pacific basin dominates the observed net westward rotation of Earth's tectonic plates

  4. Spot brazing of aluminum to copper with a cover plate

    NASA Astrophysics Data System (ADS)

    Hayashi, Junya; Miyazawa, Yasuyuki

    2014-08-01

    It is difficult to join dissimilar metals when an intermetallic compound is formed at the joining interface. Spot brazing can be accomplished in a short time by resistance heating. Therefore, it is said that the formation of a intermetallic compound can be prevented. In this study, aluminum and copper were joined by spot brazing with a cover plate. The cover plate was used to supply heat to base metals and prevent heat dissipation from the base metals. The ability to braze Al and Cu was investigated by observation and analysis. Pure aluminum (A1050) plate and oxygen-free copper (C1020) plate were used as base metals. Cu-Ni-Sn-P brazing filler was used as the brazing filler metal. SPCC was employed as cover plate. Brazing was done with a micro spot welder under an argon gas atmosphere. Brazing ability was estimated by tensile shear strength and cross sectional microstructure observation. Al and Cu can be joined by spot brazing with Cu-Ni-Sn-P brazing filler and cover plate.

  5. Dynamics of convergent plate boundaries: Insights from subduction-related serpentinite melanges from the northern edge of the Caribbean plate

    NASA Astrophysics Data System (ADS)

    García-Casco, A.

    2012-04-01

    Subduction-related rock complexes, many of them tectonic melanges, occur in the Central America-Caribbean-Andean belt. I review the lithology and P-T-t paths of HP rocks and offer interpretations and generalizations on the thermal estate of the subducting plate(s), the melange forming events, and the exhumation history of rock complexes formed in the northern branch of the Caribbean subduction zone (Cuba and nearby Guatemala and Dominican Republic; ca. 3000 km apart). These complexes contain high pressure rocks formed and exhumed at the convergent (Pacific-Atlantic) leading edge of the Caribbean plate during ca. 100 Ma (early Cretaceous-Oligocene), attesting for long lasting oceanic -followed by continental- subduction/accretion in the region. Lithologic data indicate a complex melange-forming process. In most cases, the HP rocks represent subducted MOR-related lithologies occurring as tectonic blocks within serpentinite-matrix melanges interpreted as exhumed fragments of the subduction channel(s). Most of these melanges, however, contain fragments of arc/forearc-related non metamorphic and metamorphic (low-P and high-P) sedimentary and igneous rocks. While the HP blocks of arc/forearc material indicate subduction erosion at depth, the interpretation of the LP and non-metamorphic blocks is not straight forward. Indeed, tectonic blocks of HP metamafic rocks are surrounded by antigorite-serpentinite which, in turn, is surrounded by a low-P, low-T (chrysotile-lizardite) serpentinite that makes much of the mélange. These relations indicate that the melanges represent, in fact, tectonic stacks of shallow low-T forearc serpentinite that incorporate tectonic blocks/slices of the subduction-channel (high-P, high-T serpentinite and HP metamafic blocks) and of the arc/forearc crust (low-P and non-metamorphic blocks). This picture is similar to that of HP continental margin-derived tectonic stacks containing exotic slices of antigoritite-serpentine melanges (with blocks of MORB-derived eclogite) incorporated late in the convergent history when oceanic subduction was completed. Hence, incorporation of tectonic slices of the subduction channel into the shallow (low-P, low-T) melanges and subducted/accreted continental margins occur when collision-related dynamics imposed by subduction of buoyant continental or oceanic lithosphere affected the plate margin. Aqueous fluid, sourced from both subducted sediment and metamafic/ultramafic material, was available in large quantity in the subduction environment, as indicated by massive antigoritite, rinds of metasomatic rocks around included HP metamafic rocks, retrogressed eclogite, jadeitite and hydrothermal veins within antigoritite. Such a vigorous hydrology (fluid-flow) deep in the subduction environment point to the development of wide subduction channels and explain the abundance of accreted blocks. It can also explain the scarcity of large scale (>km) slices of the subducted oceanic lithosphere in the belt, for these are likely the result of focalized distribution of deformation occurring when forearc peridotite is barely hydrated (Agard et al., Long-term coupling along the subduction plate interface: Insights from exhumed rocks and models. This session, EGU 2012). Alternatively, these large tectonic slices may have been formed by the collision dynamics caused by late-stage subduction/accretion of the continental margin (or buoyant -thick- oceanic crust). Except maturation (cooling) of the subduction zone with time at orogenic belt-scale, no other simple generalization can be reached on the thermal state of the subducting plate and the exhumation process of the subduction channel. P-T-t paths of HP rocks indicate that slab fragments ranging from cold to hot coexisted during relatively short time intervals (ca. 10 Myr), and some fragments of the subduction channel were exhumed shortly after formation while others lasted several tens of Myr to arrive to the near-surface forearc/accretionary environment. A rather variable thermal state and dynamic history of the subduction environme

  6. Dynamics of Tectonic Plates

    E-print Network

    Pechersky, E; Sadowski, G; Yambartsev, A

    2014-01-01

    We suggest a model that describes a mutual dynamic of tectonic plates. The dynamic is a sort of stick-slip one which is modeled by a Markov random process. The process defines a microlevel of the dynamic. A macrolevel is obtained by a scaling limit which leads to a system of integro-differential equations which determines a kind of mean field systems. Conditions when Gutenberg-Richter empirical law are presented on the mean field level. These conditions are rather universal and do not depend on features of resistant forces.

  7. Plated wire memory subsystem

    NASA Technical Reports Server (NTRS)

    Carpenter, K. H.

    1974-01-01

    The design, construction, and test history of a 4096 word by 18 bit random access NDRO Plated Wire Memory for use in conjunction with a spacecraft input/output and central processing unit is reported. A technical and functional description is given along with diagrams illustrating layout and systems operation. Test data is shown on the procedures and results of system level and memory stack testing, and hybrid circuit screening. A comparison of the most significant physical and performance characteristics of the memory unit versus the specified requirements is also included.

  8. Evolution of the Pacific-Juan de Fuca-North America Slab Window System: A Trench- Ridge-Fault Example From the Pacific Rim

    NASA Astrophysics Data System (ADS)

    McCrory, P. A.; Wilson, D. S.; Stanley, R. G.

    2006-12-01

    The subduction margins that rim the Pacific Ocean contain a complex record of Cenozoic slab-window interactions. The formation, growth, and healing of slab windows is generally a transient process marked by a migrating pulse of forearc volcanism derived from asthenospheric upwelling behind the trailing edges of the subducted slabs. Variations in slab-window processes result from differing plate kinematic configurations around the Pacific Rim, and can yield a series of overprinted tectonic episodes. The sequence of slab windows that formed beneath western US and Mexico starting ca. 28.5 Ma are somewhat atypical in that they mark the cessation of microplate subduction rather than continued ridge subduction. The initial `Pioneer' slab window produced an episode of forearc volcanism ca. 27-25 Ma which thermally weakened the overlying western Transverse Ranges and California Borderlands region. A second window, the `Monterey' slab window, opened beneath the same region ca. 19-15 Ma, following capture of the Monterey plate fragment by the Pacific plate. This episode is roughly coeval with initiation of western Transverse Ranges rotation, suggesting the combination of additional thermal weakening from a second slab window and the northwestward motion of a partially subducted plate fragment in concert with the Pacific plate initiated the pulling apart and clockwise pivoting of the adjacent continental crust. The similar capture of the Magdalena plate fragment by the Pacific plate and formation of the `Magdalena' slab window ca. 12.5 Ma are coeval with Baja California pulling away from the Mexican continental margin. Here, the landward break formed along the already thermally weakened volcanic arc. In California, cessation of subduction correlated with a major reconfiguration of the plate boundary. An initial period of forearc volcanism, distributed crustal extension and basin subsidence ca. 19-12.5 Ma continued until the slab window and overlying continental crust cooled and strengthened. As the locus of weakest crust shifted eastward with the active slab window, transform motion coalesced along a through-going system of strike-slip faults, including the modern San Andreas transform. We suggest similar processes occur in a range of slab-window settings as demonstrated by the crustal rotation, extension, and transform faulting documented along slab-window transients in western Canada ca. 52 and 39 Ma (Madsen et al., 2005, Geosphere) and in southern Alaska ca. 52 Ma (Cole et al., 2006, GSA Bulletin).

  9. Relating rapid plate-motion variations to plate-boundary forces in global coupled models of the mantle/lithosphere system: Effects of topography and friction

    NASA Astrophysics Data System (ADS)

    Iaffaldano, Giampiero; Bunge, Hans-Peter

    2009-09-01

    Recent high-resolution models of past plate motions and their comparison with plate motion models inferred from space geodetic techniques reveal a number of short-term variations in global plate velocities over the past 10 Myrs. Such variations serve as powerful probe into the nature and magnitude of plate boundary forces, because they are unlikely to originate from changes in mantle buoyancy forces, which evolve on longer time scales. Here we explore the constraints of the velocity record using a novel coupled modeling-approach of global neo-tectonic simulations combined with realistic plate driving forces obtained from mantle circulation models (MCMs) to arrive at simple global budgets of mantle, lithosphere and plate boundary forces. We focus on three plate boundary systems along the Nazca/South America plate margin, the Aleutian trench and the India/Australia plate boundary to show that gravitational spreading from high topography in the Andes and Tibet contributes substantially to the global plate tectonic force balance and that this contribution is sufficient to explain some 35% of recent velocity changes over the Earth's surface, including among others the observed 30% convergence reduction between the Nazca/South America plates. Our models make a number of specific predictions such as significant lateral variations in plate coupling forces along a given margin revealed by trench-parallel gravity and bathymetry anomalies and the occurrence of large earthquakes, as well as differences by as much as a factor of five from margin to margin. They also support the notion of a relatively young plate boundary separating the India and Australia plates, which has been previously suggested based on independent observations. Importantly, we find that the modeled Nazca/South America convergence reduction explains recent spreading-rate variations in the South Atlantic and South Pacific, which points to the importance of far field effects on the adjacent continents in explaining the spreading record of oceanic basins. Our numerical results demonstrate (a) that detailed budgets of forces acting upon plates can be obtained and (b) support the notion of strong forcing along weak plate boundaries.

  10. Dual cracking at polymer/glass interfaces

    NASA Astrophysics Data System (ADS)

    Ritter, John E., Jr.; Lardner, T. J.; Prakash, G. C.; Stewart, A. J.; Surorova, V.

    1993-09-01

    Moisture-assisted crack growth at polymer/glass interfaces was measured as a function of applied stain energy release rate using a four-point flexure apparatus coupled with an inverted microscope. The specimens consisted of two glass plates bonded together with a thin layer of epoxy or epoxy acrylate adhesive. Of particular importance in this study was the growth of cracks on both interfaces of the sample. Finite element analysis was carried out to gain a fundamental understanding of the observed crack growth behavior.

  11. The Plate Boundary Observatory Cascadia Network: Development and Installation of a Large Scale Real-time GPS Network

    NASA Astrophysics Data System (ADS)

    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 (<1 s) data streams (RT-GPS). These upgraded stations supplemented the original 100 RT-GPS stations in the PBO GPS network. The addition of the new RT-GPS sites in Cascadia should spur new volcano and earthquake research opportunities in an area of great scientific interest and high geophysical hazard. Streaming RT-GPS data will enable researchers to detect and investigate strong ground motion during large geophysical events, including a possible plate-interface earthquake, which has implications for earthquake hazard mitigation. A Mw 6.9 earthquake occurred on March 10, 2014, off the coast of northern California. As a response, UNAVCO downloaded high-rate GPS data from Plate Boundary Observatory stations within 500 km of the epicenter of the event, providing a good test of network performance.In addition to the 282 stations upgraded to real-time, 22 new meteorological instruments were added to existing PBO stations. Extensive testing of 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.

  12. The 1990 Western Pacific Geophysics meeting

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The 1990 Western Pacific Geophysics Meeting was held in Kanazawa, Japan from 15-21 Aug. 1990. This was the first meeting of a new series of meetings for the American Geophysical Union, and it proved to be very successful in terms of the scientific program and attendance, which included over 1,000 participants. The intent of this meeting was an effort on the part of the American Geophysical Union (AGU) and several Japanese geophysical societies to gather individual Earth and space scientists at a major scientific meeting to focus on geophysical problems being studied in the western Pacific rim. The meeting was organized along the lines of a typical AGU annual meeting with some invited talks, many contributed talks, poster sessions, and with emphasis on presentations and informal discussions. The program committee consisted of scientists from both the U.S. and Japan. This meeting provided ample opportunities for U.S. and Japanese scientists to get to know each other and their works on a one-to-one basis. It was also a valuable opportunity for students studying geophysics to get together and interact with each other and with scientists from both the U.S. and Japan. There were 939 abstracts submitted to the conference and a total of 102 sessions designed as a result of the abstracts received. The topics of interest are as follows: space geodetic and observatory measurements for earthquake and tectonic studies; gravity, sea level, and vertical motion; variations in earth rotation and earth dynamics; sedimentary magnetism; global processes and precipitation; subsurface contaminant transport; U.S. Western Pacific Rim initiatives in hydrology; shelf and coastal circulation; tectonics, magmatism, and hydrothermal processes; earthquake prediction and hazard assessment; seismic wave propagation in realistic media; and dynamics and structure of plate boundaries and of the Earth's deep interior.

  13. The East Asian Sea: A vanished Cenozoic ocean between the Pacific and Indian oceans revealed by subducted slab constraints

    NASA Astrophysics Data System (ADS)

    Wu, Jonny; Lu, Renqi; Suppe, John; Kanda, Ravi V. S.

    2014-05-01

    We have mapped an extensive 2500 km by 7500 km swath of sub-horizontal slabs at 600 to 1200 km depths that we call the 'East Asian Sea'. The northern margin of the East Asian Sea slabs begin at Taiwan and Japan, and extend south to SE Australia near New Zealand, underlying the Philippine Sea, the Caroline Sea, New Guinea, and northern to eastern Australia. When restored with other mapped slabs under Asia-Oceania, the mapped slabs reveal a vanished ocean that existed between the Pacific and Indian oceans in the Cenozoic. The subduction of the Asian Sea fills a crucial gap in plate tectonic reconstructions of East Asia by accounting for a significant proportion of fast Pacific and Indo-Australian convergence towards Eurasia since 43 Ma, during which time the Pacific moved ~3000 km WNW and Australia moved ~2500 km northward in a near-orthogonal direction relative to a mantle reference. In addition, the Australian plate expanded up to 2000 km at its northern and eastern margins. Slabs were primarily mapped from the MITP08 global P-wave mantle tomographic model (Li et al., 2008) and compared to other global P- and S-wave global tomography. Reconstructed slab lengths were assessed by quantitative flexural slip unfolding of mid-slab surfaces to a spherical Earth surface model. Seismic tomographic volumes were also calculated for selected serial cross-sections. We present a plate tectonic reconstruction with the slab constraints, with the implication that the East Asian Sea was progressively overrun and subducted beneath the Philippine Sea, the Caroline Sea and the expanding Melanesian arcs. Reconstructions to earlier periods indicate the East Asian Sea was originally Pacific or proto-Pacific mantle lithosphere, and was fragmented from the Pacific plate during the major ~45 Ma Eocene motion change. This implies that the East Asian Sea was initially the upper plate of the Mariana and Tonga-Kermadec Western Pacific subduction zones.

  14. Laser-based characterization of nuclear fuel plates

    SciTech Connect

    Smith, James A.; Cottle, Dave L.; Rabin, Barry H.

    2014-02-18

    Ensuring the integrity of fuel-clad and clad-clad bonding in nuclear fuels is important for safe reactor operation and assessment of fuel performance, yet the measurement of bond strengths in actual fuels has proved challenging. The laser shockwave technique (LST) originally developed to characterize structural adhesion in composites is being employed to characterize interface strength in a new type of plate fuel being developed at Idaho National Laboratory (INL). LST is a non-contact method that uses lasers for the generation and detection of large-amplitude acoustic waves and is well suited for application to both fresh and irradiated nuclear-fuel plates. This paper will report on initial characterization results obtained from fresh fuel plates manufactured by different processes, including hot isostatic pressing, friction stir welding, and hot rolling.

  15. Laser-Based Characterization of Nuclear Fuel Plates

    SciTech Connect

    James A. Smith; David L. Cottle; Barry H. Rabin

    2013-07-01

    Ensuring the integrity of fuel-clad and clad-clad bonding in nuclear fuels is important for safe reactor operation and assessment of fuel performance, yet the measurement of bond strengths in actual fuels has proved challenging. The laser shockwave technique (LST) originally developed to characterize structural adhesion in composites is being employed to characterize interface strength in a new type of plate fuel being developed at Idaho National Laboratory (INL). LST is a non-contact method that uses lasers for the generation and detection of large-amplitude acoustic waves and is well suited for application to both fresh and irradiated nuclear-fuel plates. This paper will report on initial characterization results obtained from fresh fuel plates manufactured by different processes, including hot isostatic pressing, friction stir welding, and hot rolling.

  16. Northeast Pacific flatfish management

    NASA Astrophysics Data System (ADS)

    Trumble, Robert J.

    1998-03-01

    Exploitation of northeast Pacific flatfish effectively began in the late 1800s with the fishery for Pacific halibut. Harvest of other flatfish occurred on a limited, local basis until foreign fishing fleets came to the area in the late 1950s. When US and Canadian fishermen replaced the foreign fleets in the 1970s and 1980s, a conservation-based management system designed to control foreign fishing was applied to the domestic fleet. Flatfish stock assessment is based on scientific surveys, both trawl and longline, and on catch-age models. In Alaskan waters since 1989 and since 1996 in Canadian waters, mandatory observers collect data on species composition, discards of flatfish and other groundfish, and catch and discards of prohibited species. Fishermen pay observer costs. Most biomass and harvest occurs in the Bering Sea-Aleutian Islands area. Many northeast Pacific flatfish are near record-high abundance, an order of magnitude higher than 20 years ago. Exploitation rates based on F35% or F0.1 generate acceptable biological catch of more than 1 million mt, but annual harvest reaches only 300,000 mt. Total groundfish harvest is limited by an optimum yield limit of 2 million mt in the Bering Sea-Aleutian Islands, where the acceptable biological catch is 3 million mt, and by limits on amounts of Pacific halibut and other prohibited species bycatch. Most flatfish are relatively low-value species, and fishermen chose to fish for more valuable species. A large, powerful fleet which developed under open access in the US saw fishing time decline and economic problems increase as catching capacity grew, while Canada stabilized its fleet with limited entry and catch restrictions for individual vessels.

  17. Plastic buckling of ARALL plates

    NASA Astrophysics Data System (ADS)

    Aboudi, J.; Paley, M.

    The plastic bifurcation buckling loads of ARALL (aramid aluminum laminate) plates are predicted. The plastic behavior of the plate is caused by the significant plasticity effects of the aluminum strips. The critical load level at which the ARALL plate loses its stability is determined from the material properties of the elastoplastic aluminum alloy strips and the elastic unidirectional aramid/epoxy composite layers, in conjunction with their geometric characteristics.

  18. Secondary states of vibrating plates

    SciTech Connect

    Matkowsky, R.J.; Putnick, L.J.; Reiss, E.L.

    1981-08-01

    A previously developed perturbation method is used to obtain a new class of periodic motions for the nonlinear vibrations of rectangular, elastic plates. The dynamic von Karman plate theory is used in the analysis. The new solutions arise by secondary bifurcation from the periodic solutions that bifurcate from the natural frequencies of free vibrations of the linearized plate theory. The new motions are a linear combination of two modes of the linearized theory.

  19. Large-scale motion between Pacific and Atlantic hotspots

    NASA Astrophysics Data System (ADS)

    Tarduno, John A.; Gee, Jeff

    1995-11-01

    STUDIES of true polar wander (TPW), the rotation of the solid Earth with respect to the spin axis1, have suggested that there has been 10-15° of relative motion over the past 130 Myr (refs 2-4). In such studies, the orientation of the spin axis is recovered from continental palaeomagnetic poles (corrected for relative plate motions), and compared with a deep-mantle reference frame defined by hotspot locations. But deducing relative plate motions becomes increasingly difficult for older (Mesozoic) time periods, hindering tests of TPW on timescales comparable to those of large-scale mantle convection; moreover, the assumption of hotspot fixity is controversial5,6. We examine here a more direct approach7,8, using palaeolatitudes derived from Pacific guyots. Contrary to predictions from TPW models, these data suggest only minor latitudinal shifts of Pacific hotspots during the Cretaceous period. Instead of TPW, relative motion between the Atlantic and Pacific hotspot groups9 is required at a velocity of approximately 30 mm yr-1, more than 50% larger than previously proposed5.

  20. A new seismically constrained subduction interface model for Central America

    NASA Astrophysics Data System (ADS)

    Kyriakopoulos, C.; Newman, A. V.; Thomas, A. M.; Moore-Driskell, M.; Farmer, G. T.

    2015-08-01

    We provide a detailed, seismically defined three-dimensional model for the subducting plate interface along the Middle America Trench between northern Nicaragua and southern Costa Rica. The model uses data from a weighted catalog of about 30,000 earthquake hypocenters compiled from nine catalogs to constrain the interface through a process we term the "maximum seismicity method." The method determines the average position of the largest cluster of microseismicity beneath an a priori functional surface above the interface. This technique is applied to all seismicity above 40 km depth, the approximate intersection of the hanging wall Mohorovi?i? discontinuity, where seismicity likely lies along the plate interface. Below this depth, an envelope above 90% of seismicity approximates the slab surface. Because of station proximity to the interface, this model provides highest precision along the interface beneath the Nicoya Peninsula of Costa Rica, an area where marked geometric changes coincide with crustal transitions and topography observed seaward of the trench. The new interface is useful for a number of geophysical studies that aim to understand subduction zone earthquake behavior and geodynamic and tectonic development of convergent plate boundaries.

  1. Glass-bead peen plating

    NASA Technical Reports Server (NTRS)

    Graves, J. R.

    1974-01-01

    Peen plating of aluminum, copper, and nickel powders was investigated. Only aluminum was plated successfully within the range of peen plating conditions studied. Optimum plating conditions for aluminum were found to be: (1) bead/powder mixture containing 25 to 35% powder by weight, (2) peening intensity of 0.007A as measured by Almen strip, and (3) glass impact bead diameter of at least 297 microns (0.0117 inches) for depositing-100 mesh aluminum powder. No extensive cleaning or substrate preparation is required beyond removing loose dirt or heavy oil.

  2. Carbon-assisted flyer plates

    DOEpatents

    Stahl, David B. (Los Alamos, NM); Paisley, Dennis L. (Santa Fe, NM)

    1994-01-01

    A laser driven flyer plate utilizing an optical fiber connected to a laser. The end of the optical fiber has a layer of carbon and a metal layer deposited onto it. The carbon layer provides the laser induced plasma which is superior to the plasma produced from most metals. The carbon layer plasma is capable of providing a flatter flyer plate, converting more of the laser energy to driving plasma, promoting a higher flyer plate acceleration, and providing a more uniform pulse behind the plate. In another embodiment, the laser is in optical communication with a substrate onto which a layer of carbon and a layer of metal have been deposited.

  3. True Shear Parallel Plate Viscometer

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin; Kaukler, William

    2010-01-01

    This viscometer (which can also be used as a rheometer) is designed for use with liquids over a large temperature range. The device consists of horizontally disposed, similarly sized, parallel plates with a precisely known gap. The lower plate is driven laterally with a motor to apply shear to the liquid in the gap. The upper plate is freely suspended from a double-arm pendulum with a sufficiently long radius to reduce height variations during the swing to negligible levels. A sensitive load cell measures the shear force applied by the liquid to the upper plate. Viscosity is measured by taking the ratio of shear stress to shear rate.

  4. Variations in oceanic plate bending along the Mariana trench

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Lin, Jian; Zhan, Wenhuan

    2014-09-01

    We quantify along-trench variations in plate flexural bending along the Mariana trench in the western Pacific Ocean. A 3-D interpreted flexural deformation surface of the subducting Pacific Plate was obtained by removing from the observed bathymetry the effects of sediment loading, isostatically-compensated topography based on gravity modeling, age-related lithospheric thermal subsidence, and residual short-wavelength features. We analyzed flexural bending of 75 across-trench profile sections and calculated five best-fitting tectonic and plate parameters that control the flexural bending. Results of analysis revealed significant along-trench variations: the trench relief varies from 0.9 to 5.7 km, trench-axis vertical loading (-V0) from -0.73×1012 to 3.17×1012 N/m, and axial bending moment (-M0) from 0.1×1017 to 2.7×1017 N. The effective elastic plate thickness seaward of the outer-rise region (TeM) ranges from 45 to 52 km, while that trench-ward of the outer-rise (Tem) ranges from 19 to 40 km. This corresponds to a reduction in Te of 21-61%. The transition from TeM to Tem occurs at a breaking distance of 60-125 km from the trench axis, which is near the outer-rise and corresponds to the onset of observed pervasive normal faults. The Challenger Deep area is associated with the greatest trench relief and axial vertical loading, while areas with seamounts at the trench axis are often associated with more subtle trench relief, smaller axial vertical loading, and greater topographic bulge at the outer-rise.

  5. The Pacific RANET Project

    NASA Astrophysics Data System (ADS)

    Postawko, S.; Ah Poe, A.; Morrissey, M.

    2004-12-01

    There are few places in the world more vulnerable to the effects of climate variability and change than the island nations of the tropical Pacific Ocean. The region also faces great challenges in communicating the issues related to climate to the general population. Lack of communications infrastructure, multiple languages, and knowledgeable personnel to deliver information, are all challenges for these countries. However, a recently developed international consortium is taking the first steps to addressing these challenges. The RANET (RAdio and interNET communications) project was originally developed for the countries of Africa, with initial funding from NOAA, to make weather, climate, and other environmental information more accessible to remote and resource-poor communities. The program is now expanding into Asia and the Pacific. RANET works to build telecommunication bridges between scientific-based products and remote communities that could benefit from such information.?The RANET project in the Pacific is a consortium of partners from the Pacific Island nations, the U.S., New Zealand, Australia, and others. Coordination of the project is loosely overseen by a Steering Committee, made up of representatives from the various interested partners. For regions where the appropriate technology exists (which includes the capital cities of nearly all of the island states of the Pacific), information is downloaded via a digital satellite receiver. This can then be broadcast within a country by many means, including Community FM Radio stations. The information distributed includes technical information needed by meteorological and related services to improve their own products and services, as well as a second level of information designed to serve communities, including weather forecasts, bulletins, warnings, etc. The primary challenge at this time is developing content that is both relevant and understandable to these remote communities. While some information will be common to all countries, it will be necessary to have more location-specific information as well. In addition to education of the general population, it is hoped that making weather, climate, and environmental information more accessible will encourage students from the islands into the study of these areas in their tertiary education.

  6. Mantle anisotropy above the deflected Pacific slab beneath Northeast China

    NASA Astrophysics Data System (ADS)

    Kaur, K.; Gao, Y.; Liu, K. H.; Gao, S. S.; Wu, J.

    2004-12-01

    Systematic spatial-variations of SKS splitting parameters (fast polarization direction PHI and splitting time DT) have been observed at global and regional broadband seismic stations in NE China and Mongolia. Based on the characteristics of the resulting splitting parameters, the study area can be divided into western and eastern regions by the western boundary of the Song-Liao Basin (SLB). A DT of about 1.5 s is observed at the eastern stations, corresponding to an anisotropic layer of about 150 km thick. Most western stations show significantly smaller DT (ranging from 0.5 to 1.0 s). The dominant PHI measurements at stations in the eastern region are about 100 degrees from the north, which are almost exactly the same as the relative plate motion directions between the Eurasian and Pacific plates calculated at each of the stations. Spatially inconsistent PHI measurements are observed at stations in the western region. The boundary between the eastern and western regions is consistent with the western limit of the subducted Pacific plate in the mantle transition zone (Widiyantoro, 1997). The slab is deflected horizontally by the 660 km discontinuity to the west by several hundred kilometers. While the difference in lithospheric deformation between the eastern and western regions could result in the observed spatial variations in anisotropy, the observations can be best explained by the nearly E-W flow in the mantle transition zone induced by the subducting slab.

  7. Effect of Decoupling of Lithospheric Plates on the Observed Geoid

    NASA Astrophysics Data System (ADS)

    Kaban, Mikhail K.; Petrunin, Alexey G.; Schmeling, Harro; Shahraki, Meysam

    2014-11-01

    A joint effect of weak zones, dividing lithospheric plates, and lateral viscosity variations (LVV) in the whole mantle on the observed geoid is investigated by a new numerical approach. This technique is based on the substantially revised method introduced by Zhang and Christensen (Geophys J Int 114:531-547, 1993) for solving the Navier-Stokes-Poisson equations in the spectral domain with strong LVV. Weak plate boundaries (WPB) are introduced based on an integrated global model of plate boundary deformations GSRM (Kreemer et al. in Geophys J Int 154:8-34, 2003). The effect of WPB on the geoid is significant and reaches -40 to 70 m with RMS ~20 m. The peaks are observed over large subduction zones in South America and the southwestern Pacific in agreement with previous studies. The positive geoid anomaly in South America could be explained largely by a dynamic effect of decoupling of the Nazca and South American plates. The negative changes of the geoid mostly relate to mid-oceanic ridges. The amplitude of the effect depends on the viscosity contrasts at WPB compared with the plate viscosity until its value reaches the limit of 2.5-3 orders of magnitude. This value might be considered as a level at which the plates are effectively decoupled. The effect of WPB exceeds the effect of LVV in the whole mantle and generally does not correlate with it. However, inclusion of LVV reduces the geoid perturbations due to WPB by about 10 m. Therefore, it is important to consider all factors together. The geoid changes mainly result from changes of the dynamic topography, which are about -300 to +500 m. The obtained results show that including WPB may significantly improve the reliability of instantaneous global dynamic models.

  8. Spatial changes of inter-plate coupling inferred from sequences of small repeating earthquakes in Japan

    NASA Astrophysics Data System (ADS)

    Igarashi, Toshihiro

    2010-10-01

    We extract sequences of small repeating earthquakes to clarify inter-plate coupling of subducting plates over a large area of the Japanese Islands. As a result, many sequences are detected at the Philippine Sea plate subducting from the Ryukyu trench and Pacific plate subducting from the Kuril-Japan trench. The average slip-rates and standard deviations estimated from the sequences show substantial spatial changes of inter-plate coupling. The large deviations of slip-rates correspond to the occurrence of episodic slips such as after-slips following large earthquakes. Constant slip-rates approaching the relative plate motion indicate weak coupling areas. Slip deficits and sparse distributions of repeating groups suggest locked areas. In the Nankai trough, deep low-frequency earthquakes in the transition zone and burst-type repeating sequences within plates have not been located in the downdip direction of groups with slow slip-rates. This suggests that the space-time characteristics of inter-plate coupling affected these seismic events.

  9. Plate tectonics, damage and inheritance.

    PubMed

    Bercovici, David; Ricard, Yanick

    2014-04-24

    The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4?billion years ago) and global tectonics (approximately 3?billion years ago) suggests that plates and plate boundaries became widespread over a period of 1?billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates. PMID:24717430

  10. 78 FR 33240 - International Fisheries; Pacific Tuna Fisheries; Fishing Restrictions in the Eastern Pacific Ocean

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-04

    ... central Pacific Ocean. In 2011, NMFS determined overfishing is occurring on Pacific bluefin tuna (76 FR...; Pacific Tuna Fisheries; Fishing Restrictions in the Eastern Pacific Ocean AGENCY: National Marine... commercial retention of Pacific bluefin tuna by U.S. fishing vessels operating in the Eastern Pacific...

  11. An Evaluation Method of Cohesive Quality in Bonded Plates Using Wavelet Transform and Neural Networks

    NASA Astrophysics Data System (ADS)

    Cui, Lian-Jun; Yang, Jing; Cheng, Jian-Chun

    2005-04-01

    A method based on a combination of wavelet transform (WT) and artificial neural networks (ANN) is presented to evaluate the cohesive quality in bonded plates using laser-generated guided waves in two-layer composite plates. The transient waveforms obtained by numerical simulations are taken as the sample database of ANN for training and learning, and the WT is used to extract the eigenvectors from the guided wave signals to simplify the structure of the ANN. The researches show that it is available to classify three kinds of interfaces, as the rigid, the weak and the slip interfaces of the adhesive layer. As to the weak interface situation, a more detailed quantitative work proves the effectiveness of the inversion of stiffness coefficients from the transient guided waves. This method provides a new promising way for the characterization of the cohesive quality in bonded plates by laser-generated guided wave detection.

  12. Evolution of the western segment of Juan Fernández Ridge (Nazca Plate): plume vs. plate tectonic processes

    NASA Astrophysics Data System (ADS)

    Lara, Luis E.; Rodrigo, Cristián; Reyes, Javier; Orozco, Gabriel

    2014-05-01

    The Juan Fernandez Ridge (Eastern Pacific, Nazca Plate) is thought to be a classic hot spot trail because of the apparent age progression observed in 40Ar-39Ar data. However, geological evidence and some thermochronological data suggest a more complex pattern with a rejuvenation stage in Robinson Crusoe Island, the most eroded of the Juan Fernandez Archipelago. In fact, a postshield stage at 900-700 ka separates the underlying shield-related pile from the post-erosional alkaline succession (Ba/Yb=38.15; La/Yb=15.66; Ba/Y=20.27; Ba/Zr=2.31). Shield volcanoes grew at high effusion rate at ca. 5-4 Ma erupting mostly tholeiitic to transitional magmas (Ba/Yb=18.07-8.32; La/Yb=4.59-9.84; Ba/Y=4.24-8.18; Ba/Zr=0.73-1.09). Taken together, shield volcanoes form a continuous plateau with a base at ca. 3900 mbsl. However, a more complex structural pattern can be inferred from geophysical data, which suggest some intracrustal magma storage and a more extended area of magma ascent. A role for the Challenger Fracture Zone is hypothesized fueling the controversy between pristine plume origin and the effect of plate tectonic processes in the origin of intraplate volcanism. This research is supported by FONDECYT Project 1110966.

  13. On plate tectonics and the geologic evolution of southwestern North America

    NASA Astrophysics Data System (ADS)

    Ward, Peter L.

    1991-07-01

    Very rapid subduction of the Farallon plate under southwestern North America between 60 and 40 Ma was accompanied by a relatively low volume of magmatism throughout the southwestern United States and northern Mexico. Between 40 and 20 Ma, when subduction slowed significantly and in one area may have even stopped, magmatism became widespread and voluminous from Nevada and Utah to central Mexico. This correlation of rapid subduction with a relatively low volume of magmatism can be explained by the observation that subduction-related andesitic arc volcanism, often formed in a Laramide-style compressional regime, is relatively low volume compared to continental volcanism. The shallow roots of arc volcanic systems are clearly exposed in the porphyry copper deposits found in currently active arcs and common throughout southwestern North America between 60 and 50 Ma. By 43 Ma, worldwide plate motions changed, the Pacific plate began moving away from North America, and subduction of the Farallon plate slowed. By around 36 Ma, the easternmost part of the East Pacific Rise, which was located between the Pioneer and Murray fracture zones, approached the trench and the young, hot, buoyant lithosphere appears to have clogged part of the subduction zone. Uplift on land became widespread. Voluminous continental magmatism formed the Sierra Madre Occidental (SMO) of Mexico, one of the largest batholiths in the world, as well as volcanic centers now exposed in the San Juan Mountains of Colorado and the Rio Grande Rift of New Mexico. Vectors of motion of the Pacific plate relative to the North American plate determined by Stock and Molnar (1988) are consistent with formation of a transtensional environment along the plate boundary sufficient to create a 100- to 200-km-wide void just landward of the old volcanic arc. While the SMO batholith was forming within this void, the Monterey and Arguello microplates just offshore to the west were broken off from the Farallon plate and rotated so that the East Pacific Rise in this immediate area became nearly perpendicular to the trench and perpendicular to the vector of motion of the Pacific plate relative to North America. Formation of the SMO batholith was followed between 24 and 20 Ma by a major increase in the rate of subduction of the Guadalupe plate, a fragment of the former Farallon plate, and by increasing mylonitization, extension, and uplift in the metamorphic core complexes that extend northwestward through southern Arizona from the northern end of the SMO batholith. The plate margin underwent another major change between 12.5 and 10 Ma when subduction again stopped, strike slip faulting became dominant along the coast, the Basin and Range Province opened, and numerous tectonostratigraphic terranes in southern California underwent large rotations. By 3 Ma a large, new terrane had been severed from North America immediately west of the SMO batholith as the Gulf of California opened. These observations can be explained by a model for the weakening and ultimate falling apart of the uppermost part of the subducted oceanic plate in the 20-30 m.y. after the end of rapid subduction. As the plate falls apart, not only is compressional stress relieved, but significant backslip along the old subduction zone is also possible, perhaps bringing blueschists rapidly upward from 20- to 30-km depths.

  14. Micro-channel plate detector

    SciTech Connect

    Elam, Jeffrey W.; Lee, Seon W.; Wang, Hsien -Hau; Pellin, Michael J.; Byrum, Karen; Frisch, Henry J.

    2015-09-22

    A method and system for providing a micro-channel plate detector. An anodized aluminum oxide membrane is provided and includes a plurality of nanopores which have an Al coating and a thin layer of an emissive oxide material responsive to incident radiation, thereby providing a plurality of radiation sensitive channels for the micro-channel plate detector.

  15. Metal vapor arc ion plating

    DOEpatents

    Bertram, L.A.; Fisher, R.W.; Mattox, D.M.; Zanner, F.J.

    1986-09-09

    A method and apparatus for ion plating are described. The apparatus uses more negative than a first electrode voltage in a vacuum arc remelt system to attract low energy ions from the anode electrode to the article to be plated. 2 figs.

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

    PubMed

    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. PMID:19390042

  17. Tomography and Dynamics of Western-Pacific Subduction Zones

    NASA Astrophysics Data System (ADS)

    Zhao, D.

    2012-01-01

    We review the significant recent results of multiscale seismic tomography of the Western-Pacific subduction zones and discuss their implications for seismotectonics, magmatism, and subduction dynamics, with an emphasis on the Japan Islands. Many important new findings are obtained due to technical advances in tomography, such as the handling of complex-shaped velocity discontinuities, the use of various later phases, the joint inversion of local and teleseismic data, tomographic imaging outside a seismic network, and P-wave anisotropy tomography. Prominent low-velocity (low-V) and high-attenuation (low-Q) zones are revealed in the crust and uppermost mantle beneath active arc and back-arc volcanoes and they extend to the deeper portion of the mantle wedge, indicating that the low-V/low-Q zones form the sources of arc magmatism and volcanism, and the arc magmatic system is related to deep processes such as convective circulation in the mantle wedge and dehydration reactions in the subducting slab. Seismic anisotropy seems to exist in all portions of the Northeast Japan subduction zone, including the upper and lower crust, the mantle wedge and the subducting Pacific slab. Multilayer anisotropies with different orientations may have caused the apparently weak shear-wave splitting observed so far, whereas recent results show a greater effect of crustal anisotropy than previously thought. Deep subduction of the Philippine Sea slab and deep dehydration of the Pacific slab are revealed beneath Southwest Japan. Significant structural heterogeneities are imaged in the source areas of large earthquakes in the crust, subducting slab and interplate megathrust zone, which may reflect fluids and/or magma originating from slab dehydration that affected the rupture nucleation of large earthquakes. These results suggest that large earthquakes do not strike anywhere, but in only anomalous areas that may be detected with geophysical methods. The occurrence of deep earthquakes under the Japan Sea and the East Asia margin may be related to a metastable olivine wedge in the subducting Pacific slab. The Pacific slab becomes stagnant in the mantle transition zone under East Asia, and a big mantle wedge (BMW) has formed above the stagnant slab. Convective circulations and fluid and magmatic processes in the BMW may have caused intraplate volcanism (e.g., Changbai and Wudalianchi), reactivation of the North China craton, large earthquakes, and other active tectonics in East Asia. Deep subduction and dehydration of continental plates (such as the Eurasian plate, Indian plate and Burma microplate) are also found, which have caused intraplate magmatism (e.g., Tengchong) and geothermal anomalies above the subducted continental plates. Under Kamchatka, the subducting Pacific slab shortens toward the north and terminates near the Aleutian-Kamchatka junction. The slab loss was induced by friction with the surrounding asthenosphere, as the Pacific plate rotated clockwise 30 Ma ago, and then it was enlarged by the slab-edge pinch-off by the asthenospheric flow. The stagnant slab finally collapses down to the bottom of the mantle, which may trigger upwelling of hot mantle materials from the lower mantle to the shallow mantle. Suggestions are also made for future directions of the seismological research of subduction zones.

  18. Tribological characteristics of gold films deposited on metals by ion plating and vapor deposition

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Spalvins, T.; Buckley, D. H.

    1984-01-01

    The graded interface between an ion-plated film and a substrate is discussed as well as the friction and wear properties of ion-plated gold. X-ray photoelectron spectroscopy (XPS) depth profiling and microhardness depth profiling were used to investigate the interface. The friction and wear properties of ion-plated and vapor-deposited gold films were studied both in an ultra high vacuum system to maximize adhesion and in oil to minimize adhesion. The results indicate that the solubility of gold on the substrate material controls the depth of the graded interface. Thermal diffusion and chemical diffusion mechanisms are thought to be involved in the formation of the gold-nickel interface. In iron-gold graded interfaces the gold was primarily dispersed in the iron and thus formed a physically bonded interface. The hardness of the gold film was influenced by its depth and was also related to the composition gradient between the gold and the substrate. The graded nickel-gold interface exhibited the highest hardness because of an alloy hardening effect. The effects of film thickness on adhesion and friction were established.

  19. Origin and subsidence of Guyots in Mid-Pacific Mountains

    NASA Astrophysics Data System (ADS)

    Winterer, Edward L.; Metzler, Christopher V.

    1984-11-01

    Morphologic and magnetic data suggest that the Mid-Pacific Mountains formed during Early Cretaceous time as a broad ENE trending double chain of midplate island seamounts over a mantle hot spot as the Pacific plate moved westward and slightly southward. Dredge, drill core, and reflection seismic data indicate that coral-rudistid reefs grew on the subsiding seamounts and evolved to atolls and banks, largely burying the volcanic foundations. Magnetic data indicate that by late Aptian time, about 110 Ma, the seamounts were located at about 20°-25°S, which we suggest was near the fringes of the latitudinal zone of vigorous reef growth, where upward growth rates could just keep up with subsidence. A broad uplift probably related to the widespread regional emplacement of Aptian volcanics as oceanic plateaus, seamounts, and deep-water flows and sills raised the Mid-Pacific Mountain reefs out of the water, and both reflection seismic and isotopic data suggest that a karstic topography developed on many of the emergent reefs. As subsidence recommenced, the reefs could hot grow upward apace with subsidence. Renewed volcanism in Late Cretaceous time in the easternmost Mid-Pacific Mountains maintained islands for a while, as at Horizon Guyot, but probably without large reefs. Elsewhere, pelagic conditions have prevailed as the guyots sank to their present-day depths. These depths are systematically related to the inferred age of the volcanic foundations, being greatest on the youngest volcanoes.

  20. 20. 'Portals and Gusset Plates for 3 180'61/2' c. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. 'Portals and Gusset Plates for 3 - 180'-6-1/2' c. to c. End Pins Single Track Through Spans, 10th, 11th, & 13th Crossings of Sacramento River, Southern Pacific Co. Sacramento Division, The Phoenix Bridge Co., C.O's. 839, 840 & 841, Drawing #12, Engineer C. Scheidl, Draftsman B. Heald, Scale 1-1/2' = 1'0', April 16th, 1901.' - Southern Pacific Railroad Shasta Route, Bridge No. 310.58, Milepost 310.58, Sims, Shasta County, CA

  1. Present-day plate motions

    NASA Technical Reports Server (NTRS)

    Minster, J. B.; Jordan, T. H.

    1977-01-01

    A data set comprising 110 spreading rates, 78 transform fault azimuths and 142 earthquake slip vectors was inverted to yield a new instantaneous plate motion model, designated RM2. The mean averaging interval for the relative motion data was reduced to less than 3 My. A detailed comparison of RM2 with angular velocity vectors which best fit the data along individual plate boundaries indicates that RM2 performs close to optimally in most regions, with several notable exceptions. On the other hand, a previous estimate (RM1) failed to satisfy an extensive set of new data collected in the South Atlantic Ocean. It is shown that RM1 incorrectly predicts the plate kinematics in the South Atlantic because the presently available data are inconsistent with the plate geometry assumed in deriving RM1. It is demonstrated that this inconsistency can be remedied by postulating the existence of internal deformation with the Indian plate, although alternate explanations are possible.

  2. PACIFIC HIGHLY MIGR ATORY PEL AGIC FISHERIES pacific highly migratory

    E-print Network

    , these fishes include yellowfin tuna, skipjack tuna, bigeye tuna, albacore, blue marlin, swordfish, dolphinfish Subtotal, temperate tunas 136,715 123,845 208,737 Billfishes Black marlin (Pacific) 1,705 1,705 Unknown Unknown Unknown Unknown Blue marlin (Pacific) 17,369 17,369 17,369 Near Not overfishing Not overfished

  3. PacificSouthwestResearchStationPrograms Pacific Southwest Research Station

    E-print Network

    PacificSouthwestResearchStationPrograms Pacific Southwest Research Station Publications List Air Pollution and Global Change Impacts on Western Forest Ecosystems Center for Urban Forest Research Chemical and Fire Effects Research Natural Areas Sierra Nevada Research Center Sudden Oak Death Research Timber

  4. Utilization of orthotropic graphite plates in plate heat exchangers, analytical modeling

    E-print Network

    Bahrami, Majid

    Utilization of orthotropic graphite plates in plate heat exchangers, analytical modeling Farshid Keywords: Orthotropic media Graphite sheet Plate heat exchanger Effectiveness Critical conductivity a b as promising alternative to conventional metallic plate heat exchangers (PHE). A new analytical model

  5. Pacific rim lures explorationists

    SciTech Connect

    Nation, L.

    1991-09-01

    The Pacific Rim has been far and away the most attractive hunting ground for explorationists in the past year. Observers point to political initiatives coupled with a growing demand as igniting the region's numerous hydrocarbon possibilities. This paper describes some of the new incentives and the resultant exploration results and developments in China, Thailand, Malaysia, Indonesia, and Vietnam. A major sign of the region's political maturity is the willingness for the countries involved to solve the longstanding disputes over the claims in hydrocarbon-prone South China Sea.

  6. The Golosyiv plate archive digitisation

    NASA Astrophysics Data System (ADS)

    Sergeeva, T. P.; Sergeev, A. V.; Pakuliak, L. K.; Yatsenko, A. I.

    2007-08-01

    The plate archive of the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (Golosyiv, Kyiv) includes about 85 000 plates which have been taken in various observational projects during 1950-2005. Among them are about 25 000 of direct northern sky area plates and more than 600 000 plates containing stellar, planetary and active solar formations spectra. Direct plates have a limiting magnitude of 14.0-16.0 mag. Since 2002 we have been organising the storage, safeguarding, cataloguing and digitization of the plate archive. The very initial task was to create the automated system for detection of astronomical objects and phenomena, search of optical counterparts in the directions of gamma-ray bursts, research of long period, flare and other variable stars, search and rediscovery of asteroids, comets and other Solar System bodies to improve the elements of their orbits, informational support of CCD observations and space projects, etc. To provide higher efficiency of this work we have prepared computer readable catalogues and database for 250 000 direct wide field plates. Now the catalogues have been adapted to Wide Field Plate Database (WFPDB) format and integrated into this world database. The next step will be adaptation of our catalogues, database and images to standards of the IVOA. Some magnitude and positional accuracy estimations for Golosyiv archive plates have been done. The photometric characteristics of the images of NGC 6913 cluster stars on two plates of the Golosyiv's double wide angle astrograph have been determined. Very good conformity of the photometric characteristics obtained with external accuracies of 0.13 and 0.15 mag. has been found. The investigation of positional accuracy have been made with A3± format fixed bed scanner (Microtek ScanMaker 9800XL TMA). It shows that the scanner has non-detectable systematic errors on the X-axis, and errors of ± 15 ?m on the Y-axis. The final positional errors are about ± 2 ?m (± 0 .2). have been obtained after corrections for systematic errors of the scanner and averaging four scans. So we may conclude that astrometric and photometric investigations may be done with precise commercial scanners. It will be necessary to scan plates at a minimum of two positions. We plan to scan the plate archive according to the priority of scientific tasks. Scanning will be done with an optical resolution of 1200 × 1200 dpi (pixel size 20 ?m), and with maximum amplitude resolution. The plate archive of MAO NASU is a unique well equipped instrument for conducting a range of astronomical investigations with a time scale of more than 50 yr.

  7. The Interaction of Lamb Waves with Solid-Solid Interfaces

    NASA Astrophysics Data System (ADS)

    Drinkwater, B. W.; Castaings, M.; Hosten, B.

    2003-03-01

    This paper deals with the topic of the interaction of Lamb waves, more specifically the A0 and S0 modes, with a solid-solid interface. This solid-solid interface is the contact between two dry, rough surfaces and could represent a kissing bond in an adhesive joint or the contacting surfaces of a bolted joint. In this paper, a very thick elastomer with high internal damping is loaded against one surface of a glass plate to create a solid-solid interface. The principal effect is shown to be increased attenuation of the guided waves propagating along the glass plate. This attenuation is caused by leakage of energy from the plate into the elastomer, where it is dissipated due to high viscoelastic damping. It is shown that the increase in attenuation is strongly dependent on the compressive load applied across the solid-solid interface. This interface is represented as a spring layer in a continuum model of the multi-layered system. Both normal and shear stiffnesses of the interface are quantified from the attenuation of A0 and S0 Lamb waves measured at each step of the compressive loading.

  8. Designing a license plate.

    PubMed

    Al-Haboubi, M H

    1999-10-01

    The majority of license plates in Saudi Arabia contain a 7-digit code to represent the registration number of vehicles. This information can be difficult to read, memorize, and reproduce in a short period of time, such as in the case of recall of hit-and-run accidents. The study reported proposes a registration code composed of 3 letters and 3 digits. This alphanumeric code can be converted into a numerical value which would give close to 20 million possible permutations, which would cover the projected number of vehicles to the year 2012. The original and proposed designs would give, in addition to two other alphanumeric codes, were tested on 60 participants using computer animations at three exposure times (1, 2, and 3 s). The results of the ANOVA on the errors committed and Sheffe tests reveal a significant difference (alpha = 0.01) between the 7-digit design and the other designs at all time intervals. Validation of the laboratory experiments were conducted on 15 different participants in the field, with similar findings. PMID:10484277

  9. Stability of active mantle upwelling revealed by net characteristics of plate tectonics.

    PubMed

    Conrad, Clinton P; Steinberger, Bernhard; Torsvik, Trond H

    2013-06-27

    Viscous convection within the mantle is linked to tectonic plate motions and deforms Earth's surface across wide areas. Such close links between surface geology and deep mantle dynamics presumably operated throughout Earth's history, but are difficult to investigate for past times because the history of mantle flow is poorly known. Here we show that the time dependence of global-scale mantle flow can be deduced from the net behaviour of surface plate motions. In particular, we tracked the geographic locations of net convergence and divergence for harmonic degrees 1 and 2 by computing the dipole and quadrupole moments of plate motions from tectonic reconstructions extended back to the early Mesozoic era. For present-day plate motions, we find dipole convergence in eastern Asia and quadrupole divergence in both central Africa and the central Pacific. These orientations are nearly identical to the dipole and quadrupole orientations of underlying mantle flow, which indicates that these 'net characteristics' of plate motions reveal deeper flow patterns. The positions of quadrupole divergence have not moved significantly during the past 250 million years, which suggests long-term stability of mantle upwelling beneath Africa and the Pacific Ocean. These upwelling locations are positioned above two compositionally and seismologically distinct regions of the lowermost mantle, which may organize global mantle flow as they remain stationary over geologic time. PMID:23803848

  10. About the REL Pacific Region

    ERIC Educational Resources Information Center

    Regional Educational Laboratory Pacific, 2014

    2014-01-01

    REL Pacific is one of ten Regional Educational Laboratories established and funded by the U.S. Department of Education's Institute of Education Sciences. Their region encompasses approximately 4.9 million square miles and serves seven Pacific island entities, including American Samoa; the Commonwealth of the Northern Mariana Islands; the Federated…

  11. At the interface between coastal and global ocean observatories - a regional, cabled observatory

    NASA Astrophysics Data System (ADS)

    Delaney, J.

    2003-04-01

    The planetary sciences are in a transformational period. New approaches made possible by a confluence of technological advances are enabling the examination of entire systems in space and time. These emerging capabilities are fostering a revolution in the exploration, discovery, and understanding of complex, interacting natural processes. The response within the ocean sciences has been the development of initiatives in several countries to create ocean observatories at global, regional, and coastal scales. Regional-scale ocean observatories have a specific and vital role in integrating across the boundaries of coastal and global observatories. To accomplish this integration, regional observatories must 1) span coastal to global systems thereby linking all processes; 2) document variability over many scales of space and time; 3) expand surface (satellite) and point (mooring) coverage to an entire volume; 4) archive data so as to enable modeling and data assimilation; 5) maximize the scientific return from the investment in a regional facility; and, 6) maintain optimal flexibility and expandability to operate for many decades. One example of a regional observatory design is the NEPTUNE facility that will be located in the northeast Pacific Ocean. NEPTUNE is intended to deliver a long-term, real-time, full-ocean presence by providing high-bandwidth communications, abundant power, robotic systems, extensive in situ networks, and real-time control for interactivity. Its 3,000-km heavily instrumented network of fiber-optic/power cables will encircle and cross the Juan de Fuca tectonic plate, enabling observations of and experiments with the volume of water above the plate, the seafloor, and the sub-seafloor. By combining earth, ocean, and atmospheric science capabilities and spanning the interface between the highly variable near shore environment and more ponderous deep sea processes NEPTUNE will offer unparalleled opportunities to a broad range of scientific, educational, and public outreach communities.

  12. Pacific Northwest: paradise lost

    SciTech Connect

    Thomas, W.V.

    1980-04-18

    An influx of new residents to the Pacific Northwest is changing social patterns and is endangering the region's valued wilderness and resources. A growing population and a feeling that the national govenment is more exploitive than conserving of its resources combines with a political tension between progressive populism and conservative Mormon influences to make residents wary of either newcomers or new prosperity. The abundant hydro power is threatened as power demand increases and utilities, industries, and the state and local governments compete for their fair share. A plan to restructure the Bonneville Power Administration (BPA) has been introduced in Congress to give it a single appointed administrator with the authority to decide how power will be distributed and which new power sources to develop. Concern about the two national nuclear waste repositories at Hanford and Idaho Falls led to a six-month moratorium at Hanford to warn the government that the site was not intended to be a permanent solution. A legislative proposal to set up regional nuclear parks will not relieve the Pacific Northwest's problems for some time. Leaders blame the policymakers for looking on the area as too remote and underpopulated to worry about. 18 references (DCK)

  13. Photovoltaic array: Power conditioner interface characteristics

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. C.; Hill, G. M.; Ross, R. G., Jr.

    1982-01-01

    The electrical output (power, current, and voltage) of flat plate solar arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as dc-to-ac power conditioners must be capable of accommodating widely varying input levels while maintaining operation at or near the maximum power point of the array. The array operating characteristics and extreme output limits necessary for the systematic design of array load interfaces under a wide variety of climatic conditions are studied. A number of interface parameters are examined, including optimum operating voltage, voltage energy, maximum power and current limits, and maximum open circuit voltage. The effect of array degradation and I-V curve fill factor or the array power conditioner interface is also discussed. Results are presented as normalized ratios of power conditioner parameters to array parameters, making the results universally applicable to a wide variety of system sizes, sites, and operating modes.

  14. Plate tectonics on the Earth triggered by plume-induced subduction initiation

    NASA Astrophysics Data System (ADS)

    Gerya, T. V.; Stern, R. J.; Baes, M.; Sobolev, S. V.; Whattam, S. A.

    2015-11-01

    Scientific theories of how subduction and plate tectonics began on Earth—and what the tectonic structure of Earth was before this—remain enigmatic and contentious. Understanding viable scenarios for the onset of subduction and plate tectonics is hampered by the fact that subduction initiation processes must have been markedly different before the onset of global plate tectonics because most present-day subduction initiation mechanisms require acting plate forces and existing zones of lithospheric weakness, which are both consequences of plate tectonics. However, plume-induced subduction initiation could have started the first subduction zone without the help of plate tectonics. Here, we test this mechanism using high-resolution three-dimensional numerical thermomechanical modelling. We demonstrate that three key physical factors combine to trigger self-sustained subduction: (1) a strong, negatively buoyant oceanic lithosphere; (2) focused magmatic weakening and thinning of lithosphere above the plume; and (3) lubrication of the slab interface by hydrated crust. We also show that plume-induced subduction could only have been feasible in the hotter early Earth for old oceanic plates. In contrast, younger plates favoured episodic lithospheric drips rather than self-sustained subduction and global plate tectonics.

  15. Plate tectonics on the Earth triggered by plume-induced subduction initiation.

    PubMed

    Gerya, T V; Stern, R J; Baes, M; Sobolev, S V; Whattam, S A

    2015-11-12

    Scientific theories of how subduction and plate tectonics began on Earth--and what the tectonic structure of Earth was before this--remain enigmatic and contentious. Understanding viable scenarios for the onset of subduction and plate tectonics is hampered by the fact that subduction initiation processes must have been markedly different before the onset of global plate tectonics because most present-day subduction initiation mechanisms require acting plate forces and existing zones of lithospheric weakness, which are both consequences of plate tectonics. However, plume-induced subduction initiation could have started the first subduction zone without the help of plate tectonics. Here, we test this mechanism using high-resolution three-dimensional numerical thermomechanical modelling. We demonstrate that three key physical factors combine to trigger self-sustained subduction: (1) a strong, negatively buoyant oceanic lithosphere; (2) focused magmatic weakening and thinning of lithosphere above the plume; and (3) lubrication of the slab interface by hydrated crust. We also show that plume-induced subduction could only have been feasible in the hotter early Earth for old oceanic plates. In contrast, younger plates favoured episodic lithospheric drips rather than self-sustained subduction and global plate tectonics. PMID:26560300

  16. Creep of phyllosilicates at the onset of plate tectonics

    SciTech Connect

    Amiguet, Elodie; Reynard, Bruno; Caracas, Razvan; Van de Moortele, Bertrand; Hilairet, Nadege; Wang, Yanbin

    2012-10-24

    Plate tectonics is the unifying paradigm of geodynamics yet the mechanisms and causes of its initiation remain controversial. Some models suggest that plate tectonics initiates when the strength of lithosphere is lower than 20-200 MPa, below the frictional strength of lithospheric rocks (>700 MPa). At present-day, major plate boundaries such as the subduction interface, transform faults, and extensional faults at mid-oceanic ridge core complexes indicate a transition from brittle behaviour to stable sliding at depths between 10 and 40 km, in association with water-rock interactions forming phyllosilicates. We explored the rheological behaviour of lizardite, an archetypal phyllosilicate of the serpentine group formed in oceanic and subduction contexts, and its potential influence on weakening of the lithospheric faults and shear zones. High-pressure deformation experiments were carried out on polycrystalline lizardite - the low temperature serpentine variety - using a D-DIA apparatus at a variety of pressure and temperature conditions from 1 to 8 GPa and 150 to 400 C and for strain rates between 10{sup -4} and 10{sup -6} s{sup -1}. Recovered samples show plastic deformation features and no evidence of brittle failure. Lizardite has a large rheological anisotropy, comparable to that observed in the micas. Mechanical results and first-principles calculations confirmed easy gliding on lizardite basal plane and show that the flow stress of phyllosilicate is in the range of the critical value of 20-200 MPa down to depths of about 200 km. Thus, foliated serpentine or chlorite-bearing rocks are sufficiently weak to account for plate tectonics initiation, aseismic sliding on the subduction interface below the seismogenic zone, and weakening of the oceanic lithosphere along hydrothermally altered fault zones. Serpentinisation easing the deformation of the early crust and shallow mantle reinforces the idea of a close link between the occurrence of plate tectonics and water at the surface of the Earth.

  17. Imprints of weak lithospheric plate boundaries in the observed geoid.

    NASA Astrophysics Data System (ADS)

    Petrunin, Alexey G.; Kaban, Mikhail K.; Schmeling, Harro; Shahraki, Meysam

    2014-05-01

    The observed geoid is highly sensitive to both: density-viscosity variations within the Earth and lithosphere dynamics. While geoid undulations induced by the mantle dynamics is a subject of numerous studies, the effect of plate tectonics on the geoid and dynamic topography remains an open issue. In present study we investigate a joint effect of weak zones, dividing lithospheric plates, and lateral viscosity variations (LVV) in the whole mantle on the observed geoid. A new numerical technique is based on the substantially revised method introduced by Zhang and Christensen (1993) for solving the Navier-Stokes-Poisson equations in the spectral domain with strong LVV. Weak plate boundaries (WPB) are introduced based on the integrated global model of plate boundary deformations GSRM (Kreemer et al., 2003). We show that the effect of WPB on the geoid is significant and reaches -40 m to 70 m with RMS ~20 m. Maximal WPB-related anomalies are observed over large subduction zones in South America and the Southwestern Pacific in agreement with previous studies. The positive geoid anomaly in South America could be explained largely by a dynamic effect of decoupling of the Nazca and South American plates. Mid-ocean ridges are mostly characterized by negative changes of the geoid compared to the model without WPB. The amplitude of the effect depends on the viscosity contrasts across WPB until its value reaches the limit of 2.5-3 orders of magnitude. This value might be considered as the level at which plates are completely decoupled. The effect of WPB alone, exceeds the effect of LVV in the whole mantle and generally does not correlate with it. However, inclusion of LVV reduces the geoid perturbations due to WPB by about 10 m. Therefore, it is important to consider all these factors together. The geoid changes mainly result from changes of the dynamic topography, which are about -300 to +500 m. The obtained results show that including WPB may significantly improve the reliability of instantaneous global dynamic models. References Zhang, S., and U. Christensen (1993), Some effects of lateral viscosity variations on geoid and surface velocities induced by density anomalies in the mantle, Geophys. J. Int., 114(3), 531-547 Kreemer, C., W. E. Holt, and A. J. Haines (2003), An integrated global model of present-day plate motions and plate boundary deformation, Geophys. J. Int., 154(1), 8-34

  18. High loading uranium fuel plate

    SciTech Connect

    Wiencek, Thomas C.; Domagala, Robert F.; Thresh, Henry R.

    1990-01-01

    Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pair of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat having a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

  19. Anomalous deepening of a belt of intraslab earthquakes in the Pacific slab crust under Kanto, central Japan: Possible anomalous thermal shielding, dehydration reactions, and seismicity caused by shallower cold slab material

    USGS Publications Warehouse

    Hasegawa, A.; Nakajima, J.; Kita, S.; Okada, T.; Matsuzawa, T.; Kirby, S.H.

    2007-01-01

    A belt of intraslab seismicity in the Pacific slab crust parallel to iso-depth contours of the plate interface has been found beneath Hokkaido and Tohoku. Hypocenter relocations have shown that this seismic belt does not run parallel to but obliquely to the iso-depth contours beneath Kanto, deepening toward the north from ???100 km to ???140 km depth. The depth limit of the contact zone with the overlying Philippine Sea slab is located close to and parallel to this obliquely oriented seismic belt, suggesting that the deepening of the seismic belt there is caused by the contact with the overlying slab. The contact with this cold slab hinders the heating of the Pacific slab crust by hot mantle wedge, which would cause delay of eclogite-forming phase transformations and hence deepening of the seismic belt there. The depth limit of the subducting low-velocity crust also deepens toward the north, supporting this idea. Copyright 2007 by the American Geophysical Union.

  20. Cenozoic East Asia plate tectonic reconstructions using constraints of mapped and unfolded slabs from mantle seismic tomography

    NASA Astrophysics Data System (ADS)

    Wu, J. E.; Suppe, J.; Kanda, R. V.

    2012-12-01

    Subducted slabs were mapped in the mantle under East Asia using MITP08 global seismic tomography (Li et al., 2008), Benioff zone seismicities and published local tomography. 3D gridded slab surfaces were constructed by manually picking and correlating the midpoint of fast seismic anomalies along variable cross-section orientations. The mapped slabs were structurally 'unfolded' and restored to the spherical Earth surface to assess their pre-subduction geometries. Gplates software was used to constrain plate tectonic reconstructions using the unfolded slabs. The unfolded SE Asia upper mantle slabs reveal a 'picture puzzle' fit along their edges that suggests a larger NE Indo-Australian ocean once existed that included the Philippine Sea, Molucca Sea and Celebes Sea. Deeper lower mantle detached slabs indicate an early to mid-Cenozoic 'East Asia Sea' between east Sundaland and the Pacific that stretched from the Ryukyu Islands north of present-day Taiwan southward to Sulawesi. The unfolded slab constraints produced gap and overlap incompatibilities when used in published plate tectonic reconstructions. Here a plate tectonic reconstruction incorporating the unfolded slab constraints is proposed that has the Philippine Sea, Molucca Sea and Celebes Sea clustered at the northern margin of Australia during the early Cenozoic. At the mid-Cenozoic these plates moved NNE with 'Australia-like' plate motions and overrode the 'East Asia Sea'. Plate motions were accommodated by N-S transforms at the eastern margin of Sundaland. Between 25 to 15 Ma the Philippine Sea, Molucca Sea and Celebes Sea plates were fragmented from the greater Indo-Australian ocean. The Philippine Sea was captured by the Pacific plate and now has Pacific-like westward motions.

  1. Is the Hawaiian-Emperor Bend Coeval for all Pacific Seamount Trails?

    NASA Astrophysics Data System (ADS)

    Koppers, A. A.; Staudigel, H.

    2004-12-01

    By far the largest number of hotspots can be found in the South Pacific Thermal and Isotopic Anomaly (SOPITA). Its Cretaceous counterpart is preserved in a large range of seamounts and guyots found in the West Pacific Seamount Province (WPSP). The seamounts in these regions display very distinct and long-lived isotopic signatures (Staudigel et al., 1991; Koppers et al., 2003) that can be used to combine source region chemistry and seamount geochronology to map out mantle melting anomalies over geological time. These mappings may resolve many important questions regarding the stationary character, continuity and longevity of the hotspots in the South Pacific mantle. Most importantly, it may also answer the question whether the Hawaiian-Emperor Bend (HEB) is coeval for all Pacific Seamount trails at 47 Ma? Fixed hotspots should be expressed in volcanic trails on the lithospheric plates revealing absolute rates of motion from their age progressions and the direction of motion based on their azimuths. By definition, bends in these hotspot trails thus should give an indication of changing plate motion happening simultaneously across individual lithospheric plates. Based on the morphology of seamounts in the Pacific, the Hawaiian-Emperor, Louisville, Gilbert Ridge and Tokelau seamount trails may be identified as the only hotspot trails to exhibit a clear HEB-type bend (Kroenke et al. 2004). Of these, the Louisville seamount trail only displays a faint bend that may be coeval with the sharp 60 degree bend in the Hawaiian-Emperor trail (Koppers et al. 2004) at 47 Ma. However, new 40Ar/39Ar analyses indicate that the HEB-type bends in the Gilberts Ridge and Tokelau seamount trails are asynchronous around 67 Ma and 57 Ma, respectively. We argue, therefore, that plate motion alone cannot explain these age systematics, but that both hotspot motion and changing lithospheric stress regimes may play an important role in their creation. The simple and elegant hotspot model that (almost without difficulty) may explain primary hotspots such as Hawaii and Louisville, seems unsatisfactory to explain the age distributions of the short-lived Gilbert Ridge and Tokelau hotspots. To explain intra-plate volcanism in the South Pacific, we argue for a combination of processes: one that forces regional magmatism from a large-scale source of buoyancy from below (like the rise of plumelets shooting off the top of a superplume that die-off after a short life-cycle) and one process that acts from above, as intra-plate extension opens up pathways that allow the lithosphere to be penetrated by magma.

  2. Carbon-assisted flyer plates

    DOEpatents

    Stahl, D.B.; Paisley, D.L.

    1994-04-12

    A laser driven flyer plate is described utilizing an optical fiber connected to a laser. The end of the optical fiber has a layer of carbon and a metal layer deposited onto it. The carbon layer provides the laser induced plasma which is superior to the plasma produced from most metals. The carbon layer plasma is capable of providing a flatter flyer plate, converting more of the laser energy to driving plasma, promoting a higher flyer plate acceleration, and providing a more uniform pulse behind the plate. In another embodiment, the laser is in optical communication with a substrate onto which a layer of carbon and a layer of metal have been deposited. 2 figures.

  3. What Are Growth Plate Injuries?

    MedlinePLUS

    ... Academy of Orthopaedic Surgeons. How Are Growth Plate Fractures Diagnosed? First, the doctor will find out how ... x rays to find out what kind of fracture it is. Third, a treatment plan is chosen. ...

  4. The multigap resistive plate chamber

    SciTech Connect

    Zeballos, E. Cerron; Crotty, I.; Hatzifotiadou, D.; Valverde, J. Lamas; Neupane, S.; Williams, M. C. S.; Zichichi, A.

    2015-02-03

    The paper describes the multigap resistive plate chamber (RPC). This is a variant of the wide gap RPC. However it has much improved time resolution, while keeping all the other advantages of the wide gap RPC design.

  5. What Are Growth Plate Injuries?

    MedlinePLUS

    ... of the following: ? Immobilization (a cast or splint) ? Manipulation or surgery (depending on where and how serious ... growth plate injuries. For example, they are: ? Studying gene therapy and finding other ways to help bones ...

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

    NASA Astrophysics Data System (ADS)

    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., <660km depth). Some of the deeply subducted material may indeed be buoyant subducted AUS continental margin (to depths of ~250-300 km), as well as subducted continental material that has reached the point of no return (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.

  7. How mantle slabs drive plate tectonics.

    PubMed

    Conrad, Clinton P; Lithgow-Bertelloni, Carolina

    2002-10-01

    The gravitational pull of subducted slabs is thought to drive the motions of Earth's tectonic plates, but the coupling between slabs and plates is not well established. If a slab is mechanically attached to a subducting plate, it can exert a direct pull on the plate. Alternatively, a detached slab may drive a plate by exciting flow in the mantle that exerts a shear traction on the base of the plate. From the geologic history of subduction, we estimated the relative importance of "pull" versus "suction" for the present-day plates. Observed plate motions are best predicted if slabs in the upper mantle are attached to plates and generate slab pull forces that account for about half of the total driving force on plates. Slabs in the lower mantle are supported by viscous mantle forces and drive plates through slab suction. PMID:12364804

  8. Large ``near junction'' thermal resistance reduction in electronics by interface nanoengineering

    E-print Network

    Daraio, Chiara

    N and SiC nanopillars at the interface to modify the vibrations of interfacial atoms by taking advantage conductance increases monotonically with Al content. The conductance for a 1 nm thick AlxGa1ÀxN only depends, improvements in the backside thermal interfaces, spreaders, heat-sinks, or cold- plates ­ th

  9. Media independent interface. Interface control document

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A Media Independent Interface (MII) is specified, using current standards in the industry. The MII is described in hierarchical fashion. At the base are IEEE/International Standards Organization (ISO) documents (standards) which describe the functionality of the software modules or layers and their interconnection. These documents describe primitives which are to transcent the MII. The intent of the MII is to provide a universal interface to one or more Media Access Contols (MACs) for the Logical Link Controller and Station Manager. This interface includes both a standardized electrical and mechanical interface and a standardized functional specification which defines the services expected from the MAC.

  10. Tectonostratigraphic terranes of the frontier circum-Pacific region

    SciTech Connect

    Howell, D.G.; Jones, D.L.; Schermer, E.R.

    1983-03-01

    Many major exploration frontiers around the Pacific are in regions where complex geologic relations reflect plate-tectonic processes, crustal mobility, and accretion of exotic terranes. The destruction of the proto-Pacific ocean (Panthalassa) involved accretion of terranes to cratonal regions such as Gondwana and Laurasia. Terranes in southwestern New Zealand and eastern Antarctica were also probably accreted during the Paleozoic. The southern margin of Siberia, extending into China, underwent a protracted period of accretion from the late Precambrian through the early Mesozoic. Mid-Paleozoic accretion is reflected in the Innuitian foldbelt of the Arctic Ocean, the Black Clastic unit of the northern Rocky Mountains, and the Antler orogeny of the western US cordillera. The Mesozoic breakup of Pangaea and the acceleration of subduction aided in the rifting and dispersal of terranes from equatorial paleolatitudes. Fragments of these terranes now compose much of the continental margins of the Pacific basin, including New Zealand, Indochina, southern China, southeast Siberia, the North American cordillera, and South America. Some terranes are presently being further fragmented by post-accretionary dispersion processes such as strike-slip faulting in western North America and Japan. Although the character and distribution of terranes in the western US are fairly well documented, details are needed for other terranes around the Pacific basin. Interpretation of structure and stratigraphy at depth will be aided by more data on the timing of accretion and the nature of deformation associated with accretion and dispersion. Such data are needed for further define specific exploration targets in the circum-Pacific region.

  11. Palaeotsunamis in the Pacific Islands

    USGS Publications Warehouse

    Goff, J.; Chague-Goff, C.; Dominey-Howes, D.; McAdoo, B.; Cronin, S.; Bonte-Grapetin, Michael, M.; Nichol, S.; Horrocks, M.; Cisternas, M.; Lamarche, G.; Pelletier, B.; Jaffe, B.; Dudley, W.

    2011-01-01

    The recent 29 September 2009 South Pacific and 27 February 2010 Chilean events are a graphic reminder that the tsunami hazard and risk for the Pacific Ocean region should not be forgotten. Pacific Islands Countries (PICs) generally have short (<150 years) historic records, which means that to understand their tsunami hazard and risk researchers must study evidence for prehistoric events. However, our current state of knowledge of palaeotsunamis in PICs as opposed to their circum-Pacific counterparts is minimal at best. We briefly outline the limited extent of our current knowledge and propose an innovative methodology for future research in the Pacific. Each PIC represents a point source of information in the Pacific Ocean and this would allow their palaeotsunami records to be treated akin to palaeo-DART?? (Deep-ocean Assessment and Reporting of Tsunamis) buoys. Contemporaneous palaeotsunamis from local, regional and distant sources could be identified by using the spatial distribution of island records throughout the Pacific Ocean in conjunction with robust event chronologies. This would be highly innovative and, more importantly, would help provide the building blocks necessary to achieve more meaningful disaster risk reduction for PICs. ?? 2010 Elsevier B.V.

  12. Impact on multilayered composite plates

    NASA Technical Reports Server (NTRS)

    Kim, B. S.; Moon, F. C.

    1977-01-01

    Stress wave propagation in a multilayer composite plate due to impact was examined by means of the anisotropic elasticity theory. The plate was modelled as a number of identical anisotropic layers and the approximate plate theory of Mindlin was then applied to each layer to obtain a set of difference-differential equations of motion. Dispersion relations for harmonic waves and correction factors were found. The governing equations were reduced to difference equations via integral transforms. With given impact boundary conditions these equations were solved for an arbitrary number of layers in the plate and the transient propagation of waves was calculated by means of a Fast Fourier Transform algorithm. The multilayered plate problem was extended to examine the effect of damping layers present between two elastic layers. A reduction of the interlaminar normal stress was significant when the thickness of damping layer was increased but the effect was mostly due to the softness of the damping layer. Finally, the problem of a composite plate with a crack on the interlaminar boundary was formulated.

  13. Precise hypocenter distribution and earthquake generating and stress in and around the upper-plane seismic belt in the subducting Pacific slab beneath NE Japan

    NASA Astrophysics Data System (ADS)

    Kita, S.; Okada, T.; Nakajima, J.; Matsuzawa, T.; Uchida, N.; Hasegawa, A.

    2007-12-01

    1. Introduction We found an intraslab seismic belt (upper-plane seismic belt) in the upper plane of the double seismic zone within the Pacific slab, running interface at depths of 70-100km beneath the forearc area. The location of the deeper limits of this belt appears to correspond to one of the facies boundaries (from jadeite lawsonite blueschist to lawsonite amphibole eclogite) in the oceanic crust [Kita et al., 2006, GRL]. In this study, we precisely relocated intraslab earthquakes by using travel time differences calculated by the waveform cross-spectrum analysis to obtain more detailed distribution of the upper plane-seismic belt within the Pacific slab beneath NE Japan. We also discuss the stress field in the slab by examining focal mechanisms of the earthquakes. 2. Data and Method We relocated events at depths of 50-00 km for the period from March 2003 to November 2006 from the JMA earthquake catalog. We applied the double-difference hypocenter location method (DDLM) by Waldhauser and Ellsworth (2000) to the arrival time data of the events. We use relative earthquake arrival times determined both by the waveform cross-spectrum analysis and by the catalog-picking data. We also determine focal mechanisms using the P wave polarity. 3. Spatial distribution of relocated hypocenters In the upper portion of the slab crust, seismicity is very active and distributed relatively homogeneously at depths of about 70-100km parallel to the volcanic front, where the upper-plane seismic belt has been found. In the lower portion of slab crust and/or the uppermost portion of the slab mantle, seismicity is spatially very limited to some small areas (each size is about 20 x 20km) at depths around 65km. Two of them correspond to the aftershock area of the 2003 Miyagi (M7.1) intraslab earthquake and that of the 1987 Iwaizumi (M6.6) intraslab earthquake, respectively. Based on the dehydration embrittelment hypothesis, the difference of the spatial distribution of the seismicity in the slab should correspond to the difference of the spatial distribution of the hydrated minerals and their dehydration reactions. In the upper slab crust, the upper-plane seismic belt is found because the hydrated minerals could be distributed homogeneously and the dehydration reaction (from jadeite lawsonite blueschist to lawsonite amphibole eclogite [Hacker et al., 2003b]) occurs perhaps largely at depth of 70-100km. Our result also suggests that in the lower portion of the slab crust and/or the uppermost portion of the slab mantle, the hydrated minerals could be inhomogeneously distributed and the seismicity occurs at depths around 65km, where another dehydration reaction may exist. 4. Characteristics of the focal mechanisms We examined the stress distribution within the slab by using focal mechanisms of the upper plane, interplane and lower plane events. From the plate interface to about 20 km below it, downdip-compressional (DC) type events are dominant. Below 20km from the plate interface, downdip-tensional (DT) type events are dominant. Many of interplane events have DC type focal mechanisms because of their locations in the uppermost portions of the slab mantle. These results indicate that the stress neutral plane from the DC type to DT type could be located at depth of about 20km from the plate interface.

  14. Low-volume intraplate volcanism in the Early/Middle Jurassic Pacific basin documented by accreted sequences in Costa Rica

    NASA Astrophysics Data System (ADS)

    Buchs, David M.; Pilet, SéBastien; Cosca, Michael; Flores, Kennet E.; Bandini, Alexandre N.; Baumgartner, Peter O.

    2013-05-01

    Countless seamounts occur on Earth that can provide important constraints on intraplate volcanism and plate tectonics in the oceans, yet their nature and origin remain poorly known due to difficulties in investigating the deep ocean. We present here new lithostratigraphic, age and geochemical data from Lower/Middle Jurassic and Lower Cretaceous sequences in the Santa Rosa accretionary complex, Costa Rica, which offer a valuable opportunity to study a small-sized seamount from a subducted plate segment of the Pacific basin. The seamount is characterized by very unusual lithostratigraphic sequences with sills of potassic alkaline basalt emplaced within thick beds of radiolarite, basaltic breccia and hyaloclastite. An integration of new geochemical, biochronological and geochronological data with lithostratigraphic observations suggests that the seamount formed ~175 Ma ago on thick oceanic crust away from subduction zones and mid-ocean ridges. This seamount traveled ~65 Ma in the Pacific before accretion. It resembles lithologically and compositionally "petit-spot" volcanoes found off Japan, which form in response to plate flexure near subduction zones. Also, the composition of the sills and lava flows in the accreted seamount closely resembles that of potassic alkaline basalts produced by lithosphere cracking along the Line Islands chain. We hypothesize based on these observations, petrological constraints and formation of the accreted seamount coeval with the early stages of development of the Pacific plate that the seamount formed by extraction of small volumes of melt from the base of the lithosphere in response to propagating fractures at the scale of the Pacific basin.

  15. Preparation of Feeder plates for ES cell culture Gelatinize Tissue Culture Plates

    E-print Network

    Preparation of Feeder plates for ES cell culture Gelatinize Tissue Culture Plates Gelatinize plates with 0.1% gelatin at room temperature for two hours. (150 µl/well of 96 well plate; 12 ml/10 cm; 4 ml/6cm. Plate cells in gelatinized plates (150 µl/well of 96 well plate; 12 ml/10 cm; 4 ml/6cm; 2 ml/well of 6

  16. Laser-Generated Leaky Rayleigh Waves at Fluid-Coating-Substrate Interfaces

    NASA Astrophysics Data System (ADS)

    Sun, Hong-xiang; Zhang, Shu-yi

    2015-06-01

    The propagation characteristics of laser-generated leaky Rayleigh waves at fluid-coating-substrate interfaces have been investigated quantitatively. Based on the plane strain and fluid-solid interaction theories, a finite-element model is developed to simulate the laser-generated leaky Rayleigh waves at the interfaces of fluid and several metal-plate configurations, such as single plates (aluminum plate and brass plate), and coating-substrate systems (aluminum-brass system and brass-aluminum system). In addition, in order to study the influences of water loading on the attenuation characteristics of the leaky Rayleigh waves, the leaky Rayleigh waves at the interfaces between these solid structures and air are also calculated for comparison.

  17. Selecting and Applying Interfacings 

    E-print Network

    2006-05-01

    Interfacing E-404 05-06 nterfacing is the layer of fabric between the outer fabric of the garment and its facing. Most garments look more professional and wear longer if they are interfaced. Selecting and using interfacing correctly is an important...-made? look. ? Care ? Select interfacings that require the same care as the garment fabric. Use washable interfacings with washable fabrics and interfacings that can be dry- cleaned with fabrics that will be dry-cleaned. If you are uncertain of the fabric?s...

  18. Seismic activities of earthquake clusters and small repeating earthquakes in Japan before and after the 2011 off the Pacific coast of Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Igarashi, T.

    2011-12-01

    The 2011 off the Pacific coast of Tohoku earthquake (M9.0) had a great effect on seismic activities over vast areas. In this study, we investigated spatio-temporal changes of seismic activities of earthquake clusters and small repeating earthquakes before and after the main shock. We have already reported many small repeating earthquakes occur at the upper boundary of the subducting plates in Japan. From these sequences, we can estimate the space-time characteristics of the inter-plate slip. In the 21st century, the resultant slip-rates correspond to relative plate motion in the Ryukyu-arc. In contrast, the shallow part and the southern part of the northeastern Japan arc indicated slip deficits. There were few after-slips following the 2005 off Miyagi earthquake (M7.2), which located near the hypocenter of the 2011 main shock. On the other hand, slip deficits of the southern shallow part were slightly decreased by after-slips following the 2003 and 2008 M7 class earthquakes. We also identified quasi-static slips associated with foreshocks off Miyagi that started from February 2011. After the main shock, we detect many small repeating earthquakes in the aftershocks. The distributions suggest after-slips near the trench of the southeastern part as well as in the deep part of the source region estimated by GPS data analysis. However, some of them are burst-type repeating sequences which occurred only after the main shock. Many continual-type repeating sequences are distributed in the southern part of the source region, and it is difficult to estimate slip-rates in the northern part at present. This uneven distribution may have been caused because observed seismograms are distorted by the multiplicity of the waves to come from various locations, the seismic velocity changes at the propagation path or site, or changes of physical properties at the plate interface. Furthermore, we automatically extracted earthquake clusters by using the unified JMA hypocenter catalogue and investigated seismicity changes before and after the main shock at each earthquake cluster. As a result, we identified seismic activities after the main shock have become active in the deep part of the source region. The largest earthquakes have occurred in some of these clusters including many small repeating earthquakes. In addition, they activate in several areas of the Philippine Sea plate and the inland shallow part. On the other hand, seismic activities decrease with some clusters in the source areas and many intra-plate clusters in intermediate-depths. It suggests the strong effect of large slips and stress changes at the main shock and/or after-slip. We should pay attention to future activities to examine whether physical property at the plate interface has changed by the high slip-rates or only earthquakes with magnitudes less than the detection limits occur in.

  19. PLATE KINEMATICS (Copyright 2010, David T. Sandwell)

    E-print Network

    Sandwell, David T.

    , Cambridge University Press, 1990, Chapter 2) Plate Motions on a Flat Earth Plate tectonic theory describes-fault-fault (R-F-F), and ridge- trench-trench (R-T-T). Each type of plate boundary has rules about relative1 PLATE KINEMATICS (Copyright 2010, David T. Sandwell) (Reference - The Solid Earth, C.M.R. Fowler

  20. A tale of two arcs? Plate tectonics of the Izu-Bonin-Mariana (IBM) arc using subducted slab constraints

    NASA Astrophysics Data System (ADS)

    Wu, J. E.; Suppe, J.; Renqi, L.; Kanda, R. V. S.

    2014-12-01

    Published plate reconstructions typically show the Izu-Bonin Marianas arc (IBM) forming as a result of long-lived ~50 Ma Pacific subduction beneath the Philippine Sea. These reconstructions rely on the critical assumption that the Philippine Sea was continuously coupled to the Pacific during the lifetime of the IBM arc. Because of this assumption, significant (up to 1500 km) Pacific trench retreat is required to accommodate the 2000 km of Philippine Sea/IBM northward motion since the Eocene that is constrained by paleomagnetic data. In this study, we have mapped subducted slabs of mantle lithosphere from MITP08 global seismic tomography (Li et al., 2008) and restored them to a model Earth surface to constrain plate tectonic reconstructions. Here we present two subducted slab constraints that call into question current IBM arc reconstructions: 1) The northern and central Marianas slabs form a sub-vertical 'slab wall' down to maximum 1500 km depths in the lower mantle. This slab geometry is best explained by a near-stationary Marianas trench that has remained +/- 250 km E-W of its present-day position since ~45 Ma, and does not support any significant Pacific slab retreat. 2) A vanished ocean is revealed by an extensive swath of sub-horizontal slabs at 700 to 1000 km depths in the lower mantle below present-day Philippine Sea to Papua New Guinea. We call this vanished ocean the 'East Asian Sea'. When placed in an Eocene plate reconstruction, the East Asian Sea fits west of the reconstructed Marianas Pacific trench position and north of the Philippine Sea plate. This implies that the Philippine Sea and Pacific were not adjacent at IBM initiation, but were in fact separated by a lost ocean. Here we propose a new IBM arc reconstruction constrained by subducted slabs mapped under East Asia. At ~50 Ma, the present-day IBM arc initiated at equatorial latitudes from East Asian Sea subduction below the Philippine Sea. A separate arc was formed from Pacific subduction below the East Asian Sea. The Philippine Sea plate moved northwards, overrunning the East Asian Sea and the two arcs collided between 15 to 20 Ma. From 15 Ma to the present, IBM arc magmatism was produced by Pacific subduction beneath the Philippine Sea.

  1. Mid-pacific mountains revisited

    NASA Astrophysics Data System (ADS)

    Kroenke, Loren W.; Kellogg, James N.; Nemoto, Kenji

    1985-06-01

    The Mid-Pacific Mountains are guyots whose volcanic pedestals have been constructed on a broad basement plateau, the flanks of which are downfaulted. Edifice construction may have been controlled by an orthogonal system of intersecting faults trending roughly ENE and NNW. Low amplitude gravity anomalies observed over the Mid-Pacific Mountains indicate complete Airy-Heiskanen isostatic compensation, crustal thickening, and eruption on thin elastic lithosphere. Tholeiites of the Mid-Pacific Mountains resemble lavas of Iceland and the Galapagos Islands. The orthogonal fault system, low gravity anomalies, and lava chemistry of the Mid-Pacific Mountains can be explained by eruption on or near a great ENE-trending rift system.

  2. ENVIRONMENT CANADA PACIFIC & YUKON REGION

    E-print Network

    ENVIRONMENT CANADA PACIFIC & YUKON REGION Fraser Basin Contaminated Sites Progress Report 1994 Abatement Office (FPAO) of Environment Canada and Contaminated Sites Remediation and Assessment Section (CSRAS) of the British Columbia Ministry of Environment, Lands and Parks entered into an agreement

  3. ENVIRONMENT CANADA PACIFIC & YUKON REGION

    E-print Network

    ENVIRONMENT CANADA PACIFIC & YUKON REGION Fraser Basin Contaminated Sites Progress Report 1995) of Environment Canada and the Contaminated Sites Remediation and Assessment Section (CSRAS) of the British Columbia Ministry of Environment, Lands and Parks entered into an agreement to collaborate

  4. Biomechanical effects of plate area and locking screw on medial open tibial osteotomy.

    PubMed

    Luo, Chu-An; Lin, Shang-Chih; Hwa, Su-Yang; Chen, Chun-Ming; Tseng, Ching-Shiow

    2015-01-01

    Medial open high tibial osteotomy (HTO) has been used to treat osteoarthritis of the medial compartment of the knee. However, weaker plate strength, unstable plate/screw junction and improper surgery technique are highly related to the HTO outcomes. Two ?-shape plates were designed and eight variations (two supporting area × four locking stiffness) were compared by finite-element method. The computed tomography-based tibia was reconstructed and both wedge micromotion and implant stresses were chosen as the comparison indices. The construct was subjected to surgical and physiological loads. The medial-posterior region is the most loaded region and the load through the posterior leg is about four times that through the anterior leg. This indicates that the two-leg design can form a force-couple mechanism to effectively reduce the implant stresses. The use of locking screws significantly decrease the screw and hole stresses. However, the extending plate reduces the stresses of screws and holes above the wedge but makes the distal screws and holes much stressed. Wedge micromotion is affected by extending plate rather than locking screw. Three factors contribute to effective stabilisation of unstable HTO wedge: (1) intimate tibia-plate contact at medial-posterior regions, (2) sufficient rigidity at plate-screw junctions and (3) effective moment-balancing design at distal tibia-plate interfaces. PMID:24617553

  5. Origin and evolution of the Pacific Superplume

    NASA Astrophysics Data System (ADS)

    Maruyama, S.

    2001-12-01

    The Pacific superplume defined as P- and S-wave velocity anomalies in the mantle underneath the southern Pacific superswell which yields a bundle of 5 hotspots. Moreover, it has been well-known that it has become active during the Cretaceous time to form a series of huge oceanic plateaus such as Ontong-Java and other oceanic Lips. I summarize the history of the Pacific superplume and speculate its origin, based on UHP experiments, tomographic images, and paleogeography back to 1.0Ga. The Pacific superplume was born when the supercontinent Rodinia was rifted to bear the Pacific Ocean in it at 750Ma. Since then it has been activated episodically at 750-700Ma, 550-500Ma, 300-250Ma and 125-85Ma, the last of which has been well-recorded on both ocean-floor and in orogenic belts. During the pulsation period, it should be emphasized that not only superplume but also the ocean-floor spreading became 30-50% faster than that of normal period. Based on UHP experiments at 660km depth and tomographic images in whole mantle, pulsation can be explained by regional mantle overturn, by which more fertile and higher-temperature materials in the lower mantle replace the upper mantle to accelerate both plate tectonics and plume activity However, the birth of superplume may be different from regional mantle overturn. Presence of cold superplume was estimated first underneath Asia by P-wave whole mantle tomography. Paleogeographic reconstruction gives us an image that cold superplume swallow many continents into a black hole to form a supercontinent. A supercontinent formed by a cold superplume must be broken up subsequently by a hot superplume underneath. The upper mantle underneath the supercontinet must be coldest among all parts of upper mantle, because of extensive subduction hence refrigeration. Moreover, subduction carries water underneath the continents, particularly in the case of subduction of cold slab. Transformation of cold to hot superplume took about 200 m.y. after the birth of supercontinent for the past three supercontinents. This transformation may be explained by water. The hydrous mantle boundary layer at 410-660 km depth is a huge water reservoir where huge amounts of stagnant megalith enriched in water would turn to be dehydrated to release water-rich fluids at 410 km depth to bear plumes with time by conductive heating underneath. The hydrous MBL underneath supercontinent causes a birth of superplume. If this is true, cold superplume may be the most essential driving force to control the EarthOs dynamics and evolution of Earth. Moreover, the role of water may be more significant than temperature, acting as a chemical agent to drive the Earth.

  6. Thermal diffusion and its influence on stress in a coated plate at the transition zone

    NASA Astrophysics Data System (ADS)

    Chepak-Gizbrekht, Maria V.

    2015-10-01

    The paper formulates the mathematical model that takes into account the heat and elements redistribution in a coated plate in the context of external heating. It is shown that, under these conditions, the thermal diffusion affects the element redistribution in coating and mechanical stresses, especially near the interface.

  7. Eulerian simulation of the perforation of aluminum plates by nondeforming projectiles

    SciTech Connect

    Silling, S.A.

    1992-03-01

    A new algorithm for the treatment of sliding interfaces between solids with or without friction in an Eulerian wavecode is described. The algorithm has been implemented in the two-dimensional version of the CTH code. The code was used to simulate penetration and perforation of aluminum plates by rigid, conical-nosed tungsten projectiles. Comparison with experimental data is provided.

  8. Dual subduction tectonics and plate dynamics of central Japan shown by three-dimensional P-wave anisotropic structure

    NASA Astrophysics Data System (ADS)

    Ishise, Motoko; Miyake, Hiroe; Koketsu, Kazuki

    2015-07-01

    The central Japanese subduction zone is characterized by a complex tectonic setting affected by the dual subduction of oceanic plates and collisions between the island arcs. To better understand of the subduction system, we performed an anisotropic tomography analysis using P-wave arrival times from local earthquakes to determine the three-dimensional structure of P-wave azimuthal anisotropy in the overriding plate and the Pacific and Philippine Sea (PHS) slabs. The principal characteristics of anisotropy in the subducted and subducting plates are (1) in the overriding plate, the distribution pattern of fast direction of crustal anisotropy coincides with that of the strike of geological structure, (2) in the two oceanic plates, fast propagation directions of P-wave were sub-parallel to the directions of seafloor spreading. Additionally, our tomographic images demonstrate that (1) the bottom of the Median Tectonic Line, the longest fault zone in Japan, reaches to the lower crust, and seems to link to the source region of an inter-plate earthquake along the PHS slab, (2) the segmentation of the PHS slab - the Izu Islands arc, the Nishi-Shichito ridge, and the Shikoku basin - due to the formation history, is reflected in the regional variation of anisotropy. The tomographic study further implies that there might be a fragment of the Pacific slab suggested by a previous study beneath the Tokyo metropolitan area. The overall findings strongly indicate that seismic anisotropy analysis provide potentially useful information to understand a subduction zone.

  9. Fluid flow plate for decreased density of fuel cell assembly

    DOEpatents

    Vitale, Nicholas G. (Albany, NY)

    1999-01-01

    A fluid flow plate includes first and second outward faces. Each of the outward faces has a flow channel thereon for carrying respective fluid. At least one of the fluids serves as reactant fluid for a fuel cell of a fuel cell assembly. One or more pockets are formed between the first and second outward faces for decreasing density of the fluid flow plate. A given flow channel can include one or more end sections and an intermediate section. An interposed member can be positioned between the outward faces at an interface between an intermediate section, of one of the outward faces, and an end section, of that outward face. The interposed member can serve to isolate the reactant fluid from the opposing outward face. The intermediate section(s) of flow channel(s) on an outward face are preferably formed as a folded expanse.

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

    NASA Technical Reports Server (NTRS)

    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.

  11. Natural vibrations of laminated anisotropic plates

    NASA Technical Reports Server (NTRS)

    Reddy, J. N.; Kuppusamy, T.

    1984-01-01

    This paper contains a description of the three-dimensional elasticity equations and the associated finite element model for natural vibrations of laminated rectangular plates. The numerical results for natural frequencies are compared with those obtained by a shear deformable plate theory. A number of cross-ply and angle-ply rectangular plates are analyzed for natural frequencies. For relatively thick plates, the plate element predicts frequencies higher than those predicted by the 3-D element.

  12. Plates for vacuum thermal fusion

    DOEpatents

    Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

    2002-01-01

    A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

  13. Media independent interface

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The work done on the Media Independent Interface (MII) Interface Control Document (ICD) program is described and recommendations based on it were made. Explanations and rationale for the content of the ICD itself are presented.

  14. Western Pacific thermocline structure and the Pacific marine Intertropical Convergence Zone during the Last Glacial Maximum

    E-print Network

    Lynch-Stieglitz, Jean

    Western Pacific thermocline structure and the Pacific marine Intertropical Convergence Zone during and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332, USA b NOAA Keywords: Last Glacial Maximum western tropical pacific Intertropical Convergence Zone oxygen isotopes

  15. Plate bending at subduction zones: Consequences for the direction of plate motions

    E-print Network

    between plate bending and various sources of friction at plate boundaries and in the interior toward the trench, especially when the downgoing plate has a distribution of ages [10], and hencePlate bending at subduction zones: Consequences for the direction of plate motions Bruce A. Buffett

  16. SEM Characterization of an Irradiated Monolithic U-10Mo Fuel Plate

    SciTech Connect

    D. D. Keiser, Jr.; J. F. Jue; A. B. Robinson

    2010-03-01

    Results of scanning electron microscopy (SEM) characterization of irradiated U-7Mo dispersion fuel plates with differing amounts of matrix Si have been reported. However, to date, no results of SEM analysis of irradiated U-Mo monolithic fuel plates have been reported. This paper describes the first SEM characterization results for an irradiated monolithic U-10Mo fuel plate. Two samples from this fuel plate were characterized. One sample was produced from the low-flux side of the fuel plate, and another was produced at the high-flux side of the fuel plate. This characterization focused on the microstructural features present at the U-10Mo foil/cladding interface, particularly the interaction zone that had developed during fabrication and irradiation. In addition, the microstructure of the foil itself was investigated, along with the morphology of the observed fission gas bubbles. It was observed that a Si-rich interaction layer was present at the U-10Mo foil/cladding interface that exhibited relatively good irradiation behavior, and within the U-10Mo foil the microstructural features differed in some respects from what is typically seen in the U-Mo powders of an irradiated dispersion fuel.

  17. Seismicity of the Earth 1900-2010 eastern margin of the Australia plate

    USGS Publications Warehouse

    Benz, Harley M.; Herman, Matthew; Tarr, Arthur C.; Hayes, Gavin P.; Furlong, Kevin P.; Villaseñor, Antonio; Dart, Richard L.; Rhea, Susan

    2011-01-01

    The eastern margin of the Australia plate is one of the most seismically active areas of the world due to high rates of convergence between the Australia and Pacific plates. In the region of New Zealand, the 3,000 km long Australia-Pacific plate boundary extends from south of Macquarie Island to the southern Kermadec Island chain. It includes an oceanic transform (the Macquarie Ridge), two oppositely verging subduction zones (Puysegur and Hikurangi), and a transpressive continental transform, the Alpine Fault through South Island, New Zealand. Since 1900, there have been 15 M7.5+ earthquakes recorded near New Zealand. Nine of these, and the four largest, occurred along or near the Macquarie Ridge, including the 1989 M8.2 event on the ridge itself, and the 2004 M8.1 event 200 km to the west of the plate boundary, reflecting intraplate deformation. The largest recorded earthquake in New Zealand itself was the 1931 M7.8 Hawke's Bay earthquake, which killed 256 people. The last M7.5+ earthquake along the Alpine Fault was 170 years ago; studies of the faults' strain accumulation suggest that similar events are likely to occur again.

  18. Gravity, Bathymetry and Submarine Volcanism in the Mesozoic Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Watts, A. B.; Kalnins, L. M.

    2007-12-01

    Submarine volcano loading studies suggest that the effective elastic thickness, Te, of oceanic lithosphere increases with age at the time of loading. Therefore, a seamount formed on a ridge crest will be characterised by a lower Te than a similar size feature that formed off-ridge. Compilations of data where both crustal and sample ages are known show that Te is given approximately by the depth to the 450° oceanic isotherm, based on plate cooling models. By comparing observed bathymetry and gravity anomalies to predictions based on simple elastic plate models it is possible to estimate Te and hence the age of oceanic lithosphere at the time of loading at bathymetric features of unknown tectonic setting. Early results based on ~100 features suggested that Hess Rise, Necker ridge, Line Islands, and Manihiki Plateaus formed on-ridge and, hence, that there was a major period of volcanism in the central Pacific ~90- 120 Ma. This 'event' appears to have been accompanied by deep-water volcanism, as shown by the pioneering work of Roger L. Larson in the Nauru Basin. Recently, Watts et al. (2006) used a bathymetric prediction technique to estimate the Te at >9000 seamounts in the Wessel (2001) database. Plots of Te Vs. age at features of known age, however, revealed considerable scatter with many lower values at old ages than expected. Te maps show that these low values form a broad swath from East Pacific Rise crest in the SE, through the Tuamotu Plateau region, to the Line and Marshall Islands and Mid-Pacific Mountains in the NW. The SE end of the swath includes the region dubbed the South Pacific Isotopic and Thermal Anomaly (SOPITA) and some features (e.g. Marcus Wake Guyots, Lines Islands) at the NW end backtrack into the SOPITA. Therefore, some of the scatter maybe caused by a regional shallowing of the controlling isotherm. This has been verified using a moving window admittance technique which suggest controlling isotherms of <~350° as the SOPITA region is approached. These new constraints on the controlling isotherms are used here to estimate the distribution of submarine volcanism in the Mesozoic Pacific Ocean through time.

  19. The Dynamics and Evolution of the African and Pacific LLSVPs

    NASA Astrophysics Data System (ADS)

    Bull, A. L.; Thomas, C.

    2014-12-01

    Numerical studies of mantle convection have attempted to explain tomographic observations that reveal a lower mantle dominated by broad regional areas of lower-than-average shear-wave speeds beneath Africa and the Central Pacific. Termed LLSVPs ("large low shear velocity provinces"), the anomalous regions are often inferred to be thermochemical structures encircled by regions of higher-than-average shear-wave speeds associated with Mesozoic and Cenozoic subduction zones. Geochemical inferences of multiple chemical reservoirs at depth, strong seismic contrasts, an anti-correlation of shear-wave velocity to bulk sound velocity and increased density in the anomalous regions support a thermochemical origin for the LLSVPs. The origin and long-term evolution of the anomalous regions remains enigmatic. It has been proposed that the LLSVP beneath Africa was not present before 200 Ma (i.e. before and during most of the life-time of the supercontinent Pangea), prior to which time the lower mantle was dominated by a degree-1 convection pattern with a major upwelling centred close to the present-day Pacific LLSVP and subduction concentrated mainly in the antipodal hemisphere. The African LLSVP would thus have formed during the time-frame of the supercontinent Pangea as a result of return flow in the mantle due to circum-Pacific subduction. We present new results from a geodynamic-seismology study that investigates the hypothesis that the Pacific LLSVP is indeed much older than its antipodal counterpart by performing 3D numerical models of mantle convection integrated with a new plate tectonic history model. We improve upon previous studies by imposing kinematic surface velocity boundary conditions for a time interval that spans the amalgamation and subsequent break-up of Pangea and by allowing for a lateral heterogeneity difference between the African and the Pacific LLSVP. Our results are distinct from those of previous studies in several important ways: our plate model explicitly includes (i) absolute longitudinal reconstructions and (ii) TPW-correction, (iii) our model extends back to the mid-Paleozoic (410 Ma) and (iii) we include lateral compositional variations between the two antipodal LLSVPs.

  20. An adjoint-based FEM optimization of coseismic displacements following the 2011 Tohoku earthquake: new insights for the limits of the upper plate rebound

    NASA Astrophysics Data System (ADS)

    Pulvirenti, Fabio; Jin, Shuanggen; Aloisi, Marco

    2014-12-01

    The 11 March 2011 Tohoku earthquake was the strongest event recorded in recent historic seismicity in Japan. Several researchers reported the deformation and possible mechanism as triggered by a mega thrust fault located offshore at the interface between the Pacific and the Okhotsk Plate. The studies to estimate the deformation in detail and the dynamics involved are still in progress. In this paper, coseismic GPS displacements associated with Tohoku earthquake are used to infer the amount of slip on the fault plane. Starting from the fault displacements configuration proposed by Caltech-JPL ARIA group and Geoazur CNRS, an optimization of these displacements is performed by developing a 3D finite element method (FEM) model, including the data of GPS-acoustic stations located offshore. The optimization is performed for different scenarios which include the presence of topography and bathymetry (DEM) as well as medium heterogeneities. By mean of the optimized displacement distribution for the most complete case (heterogeneous with DEM), a broad slip distribution, not narrowly centered east of hypocenter, is inferred. The resulting displacement map suggests that the beginning of the area of subsidence is not at east of MYGW GPS-acoustic station, as some researchers have suggested, and that the area of polar reversal of the vertical displacement is rather located at west of MYGW. The new fault slip distribution fits well for all the stations at ground and offshore and provides new information on the earthquake generation process and on the kinematics of Northern Japan area.

  1. Northern east Pacific rise: Magnetic anomaly and bathymetric framework

    SciTech Connect

    Klitgord, K.D.; Mammerickx, J.

    1982-08-10

    The oceanic crust in the eastern Pacific between 7/sup 0/N and 30/sup 0/N and east of 127/sup 0/W contains a fairly complete history of the spreading centers associated with the East Pacific Rise since 25 m.y. B.P. (late Oligocene). In this paper, we have summarized the seafloor spreading magnetic-anomaly data and the bathymetric data that reflect the record of this technique history. The well-defined magnetic lineations north of the Clarion fracture zone, in the mouth of the Gulf of California, and on the east flank of the East Pacific Rise (EPR) are carefully examined and used to provide a guide for interpreting the spreading pattern between the Clarion and Clipperton fracture zones, southward of the Rivera fracture zone over the Mathematician Ridge, and over the entire EPR east of the Mathematician Ridge between the Rivera and Siqueiros fracture zones. The bathymetric data provide a trace of the fracture zone pattern in each of the above mentioned areas. The fracture zone bathymetry and the seafloor spreading magnetc lineations on the EPR south of the Rivera fracture zone have a distinctive fanning pattern caused by close poles of rotation and plate boundary reorganizations. All these data provide a good record of the plate reorganizations in the middle Miocene at magnetic anomaly 5A time (12.5 to 11 m.y. B.P.), in the late Miocene at a magnetic anomaly 3'--4 time (6.5 m.y. B.P.), and in the Pliocene at magnetic anomaly 2'--3 time (3.5 m.y.B.P.). Several abandoned spreading centers, including the Mathematician Ridge, were left behind as a result of these reorganizations. The Mathematician Ridge is shown to be a set of ridges and trough whose origin is related to the tectonics activity associated with each of the above mentioned reorganizations since anomaly 5A.

  2. The longevity of the South Pacific isotopic and thermal anomaly

    USGS Publications Warehouse

    Staudigel, H.; Park, K.-H.; Pringle, M.; Rubenstone, J.L.; Smith, W.H.F.; Zindler, A.

    1991-01-01

    The South Pacific is anomalous in terms of the Sr, Nd, and Pb isotope ratios of its hot spot basalts, a thermally enhanced lithosphere, and possibly a hotter mantle. We have studied the Sr, Nd, and Pb isotope characteristics of 12 Cretaceous seamounts in the Magellans, Marshall and Wake seamount groups (western Pacific Ocean) that originated in this South Pacific Isotopic and Thermal Anomaly (SOPITA). The range and values of isotope ratios of the Cretaceous seamount data are similar to those of the island chains of Samoa, Tahiti, Marquesas and Cook/Austral in the SOPITA. These define two major mantle components suggesting that isotopically extreme lavas have been produced at SOPITA for at least 120 Ma. Shallow bathymetry, and weakened lithosphere beneath some of the seamounts studied suggests that at least some of the thermal effects prevailed during the Cretaceous as well. These data, in the context of published data, suggest: 1. (1)|SOPITA is a long-lived feature, and enhanced heat transfer into the lithosphere and isotopically anomalous mantle appear to be an intrinsic characteristic of the anomaly. 2. (2)|The less pronounced depth anomaly during northwesterly plate motion suggests that some of the expressions of SOPITA may be controlled by the direction of plate motion. Motion parallel to the alignment of SOPITA hot spots focusses the heat (and chemical input into the lithosphere) on a smaller cross section than oblique motion. 3. (3)|The lithosphere in the eastern and central SOPITA appears to have lost its original depleted mantle characteristics, probably due to enhanced plume/lithosphere interaction, and it is dominated by isotopic compositions derived from plume materials. 4. (4)|We speculate (following D.L. Anderson) that the origin of the SOPITA, and possibly the DUPAL anomaly is largely due to focussed subduction through long periods of the geological history of the earth, creating a heterogeneous distribution of recycled components in the lower mantle. ?? 1991.

  3. Vortex dynamics around pitching plates

    NASA Astrophysics Data System (ADS)

    Jantzen, Ryan T.; Taira, Kunihiko; Granlund, Kenneth O.; Ol, Michael V.

    2014-05-01

    Vortex dynamics of wakes generated by rectangular aspect-ratio 2 and 4 and two-dimensional pitching flat plates in free stream are examined with direct numerical simulation and water tunnel experiments. Evolution of wake vortices comprised of tip, leading-edge, and trailing-edge vortices is compared with force history for a range of pitch rates. The plate pivots about its leading edge with reduced frequency from ?/8 to ?/48, which corresponds to pitching over 1 to 6 chord lengths of travel. Computations have reasonable agreement with experiments, despite large differences in Reynolds number. Computations show that the tip effects are confined initially near the wing tips, but begin to strongly affect the leading-edge vortex as the motion of the plate proceeds, with concomitant effects on lift and drag history. Scaling relations based on reduced frequency are shown to collapse aerodynamic force history for the various pitch rates.

  4. Center for Nanostructured Biomimetic Interfaces A Bioelectronic Sensor Interface Based

    E-print Network

    Center for Nanostructured Biomimetic Interfaces A Bioelectronic Sensor Interface Based, 2004, Austin, TX #12;Center for Nanostructured Biomimetic Interfaces Presentation Outline Background Biomimetic Interfaces Background Dehydrogenase enzymes Catalyze electron transfer reactions · Activity easily

  5. Continuing evolution of the Pacific-Juan de Fuca-North America slab window system-A trench-ridge-transform example from the Pacific Rim

    USGS Publications Warehouse

    McCrory, P.A.; Wilson, D.S.; Stanley, R.G.

    2009-01-01

    Many subduction margins that rim the Pacific Ocean contain complex records of Cenozoic slab-window volcanism combined with tectonic disruption of the continental margin. The series of slab windows that opened beneath California and Mexico starting about 28.5 Ma resulted from the death of a series of spreading ridge segments and led to piecewise destruction of a subduction regime. The timing and areal extent of the resultant slab-window volcanism provide constraints on models that depict the subsequent fragmentation and dispersal of the overlying continental margin. The initial Pioneer slab window thermally weakened the overlying western Transverse Ranges and California Borderlands region starting about 28.5 Ma. A second thermal pulse occurred in the same region starting about 19 Ma during growth of the Monterey slab window. This additional heating, combined with the capture of a partially subducted Monterey plate fragment by the Cocos plate, initiated the pulling apart and rotation of the adjacent continental margin. Similarly, the capture of Guadalupe and Magdalena plate fragments by the Pacific plate and initiation of the Guadalupe-Magdalena slab window about 12.5 Ma are coeval with Baja California pulling away from the Mexico continental margin, with the break along the Comondú arc, in crust already thermally weakened by about 10 My of volcanism. In coastal California, distributed crustal extension and subsidence accompanied the new transform plate boundary, and continued until the slab windows cooled and plate motion coalesced along a through-going system of strike-slip faults. The transform boundary continues to evolve, and forward modeling predicts an instability with the current configuration as a result of convergence between the Sierra Nevada and Peninsular Ranges batholiths, starting about 2 My in the future. The instability may be resolved by a shift in the locus of transform motion from the San Andreas fault to the eastern California shear zone, or by breaking off another fragment of the Mojave or southern Sierra Nevada crustal blocks and translating it northward.

  6. 3-D Shear Wave Speed Structure Beneath the Philippine Sea Plate

    NASA Astrophysics Data System (ADS)

    Isse, T.; Yoshizawa, K.; Shiobara, H.; Shinohara, M.; Nakahigashi, K.; Mochizuki, K.; Sugioka, H.; Suetsugu, D.; Kanazawa, T.; Fukao, Y.

    2004-12-01

    The Philippine sea is a marginal basin in large part opened through the two episodes of back-arc spreading. The evolution history of the Philippine Sea plate should be reflected in the upper mantle structure. However, the spatial resolution achieved by previous studies is not good enough to discuss seismological structures in terms of the plate tectonic history. Recently, several stations in oceanic islands have been installed and long-term broadband seismic observations on the seafloor have been conducted as a part of the Ocean Hemisphere Project (OHP). These seismic observations, in addition to existing data, enable us to reveal the seismic structure of the Philippine Sea plate with an unprecedented resolution. We measured phase velocities of the fundamental and first three higher modes of Rayleigh waves for the source-station pairs within a latitudinal range from -20oS to 45oN and a longitudinal range from 110oE to 165oE, using a fully non-linear waveform inversion method by Yoshizawa and Kennett (2002). The measured multi-mode phase velocities are inverted to a 3-D shear wave speed structure using the three-stage inversion technique by Yoshizawa and Kennett (2004), which allows us to incorporate the effects of finite frequency as well as ray path deviation from the great-circle. The inverted model has a good resolution in the upper 250km of the mantle, showing a persistent feature of subduction of the Pacific plate against the Philippine Sea plate along the Izu-Bonin-Mariana trenches. Subduction of the Philippine Sea plate beneath the Philippine islands can also be seen. The thickness of the Philippine Sea plate is in general significantly thinner than the Pacific plate and the shear wave speed in the asthenosphere is very slow. The southern, older part of the Philippine Sea plate is much thicker than the rest. The slowest shear wave speed of the Philippine Sea plate can be found along its spreading axis at the Mariana trough.

  7. Microstructural Characterization of Burnable Absorber Materials Being Evaluated for Application in LEU U-Mo Fuel Plates

    SciTech Connect

    J. F. Jue; B. Miller; B. Yao; E. Perez; Y. H. Sohn

    2011-03-01

    The starting microstructure of a fuel plate will impact how it performs during irradiation. As a result, microstructural characterization has been performed on as-fabricated monolithic fuel plates to determine the changes in fuel plate microstructure that may result from changes in fabrication parameters. Particular focus has been given to the fuel plate U-10Mo/Zr and Zr/AA6061 cladding interfaces, since the integrity of these interfaces will play a big role in determining the overall performance of the fuel plate during irradiation. In addition, burnable absorber materials for potential incorporation into monolithic fuel plates have been characterized to identify their as-fabricated microstructures. This information will be important when trying to understand the PIE data from fuel plates with burnable absorbers that are irradiated in future irradiation experiments. This paper will focus on the microstructures observed using optical metallography, X-ray diffraction, and scanning and transmission electron microscopy for monolithic fuel plates exposed to different fabrication parameters and for as-fabricated burnable absorber materials.

  8. Color Anodizing of Titanium Coated Rolled Carbon Steel Plate

    SciTech Connect

    Sarajan, Zohair; Mobarakeh, Hooman Nikbakht; Namiranian, Sohrab

    2011-12-26

    As an important kind of structural materials, the titanium cladded steel plates have the advantages of both metals and have been applied in aviation, spaceflight, chemical and nuclear industries. In this study, the specimens which were prepared under soldering mechanism during rolling were anodized by electrochemical process under a given conditions. The color anodizing takes place by physical phenomenon of color interference. Part of incident light on the titanium oxide is reflected and the other part reflects inside coated titanium layer. Major part of the light which reflects from titanium-oxide interface, reflects again inside of the oxide layer.

  9. Analysis of Interplanetary Dust Experiment Detectors and Other Witness Plates

    NASA Technical Reports Server (NTRS)

    Griffis, D. P.; Wortman, J. J.

    1992-01-01

    The development of analytical procedures for identifying the chemical composition of residue from impacts that occurred on the Interplanetary Dust Experiment (IDE) detectors during the flight of Long Duration Exposure Facility (LDEF) and the carrying out of actual analysis on IDE detectors and other witness plates are discussed. Two papers on the following topics are presented: (1) experimental analysis of hypervelocity microparticle impact sites on IDE sensor surfaces; and (2) contaminant interfaces with secondary Ion Mass Spectrometer (SIMS) analysis of microparticle impactor residues on LDEF surfaces.

  10. Quantization of interface currents

    SciTech Connect

    Kotani, Motoko; Schulz-Baldes, Hermann; Villegas-Blas, Carlos

    2014-12-15

    At the interface of two two-dimensional quantum systems, there may exist interface currents similar to edge currents in quantum Hall systems. It is proved that these interface currents are macroscopically quantized by an integer that is given by the difference of the Chern numbers of the two systems. It is also argued that at the interface between two time-reversal invariant systems with half-integer spin, one of which is trivial and the other non-trivial, there are dissipationless spin-polarized interface currents.

  11. Multimodal interfaces: Challenges and perspectives

    E-print Network

    Sebe, Nicu

    Multimodal interfaces: Challenges and perspectives Nicu Sebea,b a University of Amsterdam has been a technology-driven process. However, the newly developed multimodal interfaces are using trends in multimodal interfaces research. Keywords: Multimodal interfaces, human-centered computing

  12. Orbiter middeck/payload standard interfaces control document

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The interfaces which shall be provided by the baseline shuttle mid-deck for payload use within the mid-deck area are defined, as well as all constraints which shall be observed by all the users of the defined interfaces. Commonality was established with respect to analytical approaches, analytical models, technical data and definitions for integrated analyses by all the interfacing parties. Any payload interfaces that are out of scope with the standard interfaces defined shall be defined in a Payload Unique Interface Control Document (ICD) for a given payload. Each Payload Unique ICD will have comparable paragraphs to this ICD and will have a corresponding notation of A, for applicable; N/A, for not applicable; N, for note added for explanation; and E, for exception. On any flight, the STS reserves the right to assign locations to both payloads mounted on an adapter plate(s) and payloads stored within standard lockers. Specific locations requests and/or requirements exceeding standard mid-deck payload requirements may result in a reduction in manifesting opportunities.

  13. Deformation across the western United States: A local estimate of Pacific-North America transform deformation

    NASA Technical Reports Server (NTRS)

    Humphreys, Eugene D.; Weldon, Ray J., II

    1994-01-01

    We obtain a locally based estimate of Pacific-North America relative motion and an uncertainly in this estimate by integrating deformation rate along three different paths leading west across southwestern North America from east of the Rio Grande Rift to near the continental escarpment. Data are primarily Quatenary geologic slip rates estimates, and resulting deformation determinations therefore are 'instantaneous' in a geologic sense but 'long term' with respect to earthquake cycles. We deduce a rate of motion of the Pacific plane relative to North America that is 48 +/- 2 mm/yr, a rate indistinguishable from that predicted by the global kinematics models RM2 and NUVEL-1; however, we obtain an orientation that is 5-9 deg counterclockwise of these models. A more westerly motion of the Pacific plate, with respect to North America, is calculated from all three paths. The relatively westerly motion of the Pacific plate is accomodated by deformation in the North American continent that includes slip on relatively counterclockwise-oriented strike-slip faults (including the San Andreas fault), whic is especially relevant in and south of the Transverse Ranges, and a margin-normal component of net extension across the continent, which is especially relevant north of the Transverse Ranges. Deformation of the SW United States occurs in regionally coherent domains within the style of deformation is approximately uniform.

  14. Developing a laser shockwave model for characterizing diffusion bonded interfaces

    NASA Astrophysics Data System (ADS)

    Lacy, Jeffrey M.; Smith, James A.; Rabin, Barry H.

    2015-03-01

    The US National Nuclear Security Agency has a Global Threat Reduction Initiative (GTRI) with the goal of reducing the worldwide use of high-enriched uranium (HEU). A salient component of that initiative is the conversion of research reactors from HEU to low enriched uranium (LEU) fuels. An innovative fuel is being developed to replace HEU in high-power research reactors. The new LEU fuel is a monolithic fuel made from a U-Mo alloy foil encapsulated in Al-6061 cladding. In order to support the fuel qualification process, the Laser Shockwave Technique (LST) is being developed to characterize the clad-clad and fuel-clad interface strengths in fresh and irradiated fuel plates. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves to characterize interfaces in nuclear fuel plates. However, because the deposition of laser energy into the containment layer on a specimen's surface is intractably complex, the shock wave energy is inferred from the surface velocity measured on the backside of the fuel plate and the depth of the impression left on the surface by the high pressure plasma pulse created by the shock laser. To help quantify the stresses generated at the interfaces, a finite element method (FEM) model is being utilized. This paper will report on initial efforts to develop and validate the model by comparing numerical and experimental results for back surface velocities and front surface depressions in a single aluminum plate representative of the fuel cladding.

  15. Developing a laser shockwave model for characterizing diffusion bonded interfaces

    SciTech Connect

    Lacy, Jeffrey M. Smith, James A. Rabin, Barry H.

    2015-03-31

    The US National Nuclear Security Agency has a Global Threat Reduction Initiative (GTRI) with the goal of reducing the worldwide use of high-enriched uranium (HEU). A salient component of that initiative is the conversion of research reactors from HEU to low enriched uranium (LEU) fuels. An innovative fuel is being developed to replace HEU in high-power research reactors. The new LEU fuel is a monolithic fuel made from a U-Mo alloy foil encapsulated in Al-6061 cladding. In order to support the fuel qualification process, the Laser Shockwave Technique (LST) is being developed to characterize the clad-clad and fuel-clad interface strengths in fresh and irradiated fuel plates. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves to characterize interfaces in nuclear fuel plates. However, because the deposition of laser energy into the containment layer on a specimen's surface is intractably complex, the shock wave energy is inferred from the surface velocity measured on the backside of the fuel plate and the depth of the impression left on the surface by the high pressure plasma pulse created by the shock laser. To help quantify the stresses generated at the interfaces, a finite element method (FEM) model is being utilized. This paper will report on initial efforts to develop and validate the model by comparing numerical and experimental results for back surface velocities and front surface depressions in a single aluminum plate representative of the fuel cladding.

  16. Interface control and snow crystal growth

    E-print Network

    Jessica Li; Laura P. Schaposnik

    2015-05-08

    The growth of snow crystals is dependent on the temperature and saturation of the environment. In the case of dendrites, Reiter's local two-dimensional model provides a realistic approach to the study of dendrite growth. In this paper we obtain a new geometric rule that incorporates interface control, a basic mechanism of crystallization that is not taken into account in the original Reiter's model. By defining two new variables, growth latency and growth direction, our improved model gives a realistic model not only for dendrite but also for plate forms.

  17. Petroleum geology of Pacific margin of Central America and northern South America, from Guatemala to Ecuador

    SciTech Connect

    Scrutton, M.E.; Escalante, G.F.

    1986-07-01

    Exploration for hydrocarbons along the Pacific margin of Central America and northern South America has been limited and spasmodic. Less than 100 exploration wells have been drilled, with nearly 50 of these being in the Santa Elena, Progreso, and Guayas basins in Ecuador. Shows have been reported in some wells, and a few oil seeps are known. The only commercial production established to date has been from the Santa Elena Peninsula in Ecuador in the extreme south of the study area. Understanding of the geology in this part of the continental margin is incomplete at best. This paper reviews present-day knowledge in an attempt to define the sedimentary basins better, to characterize their structure and stratigraphy, and to assess their petroleum prospects. The area of continental margin reviewed is to the north, located northwest of the trench system where oceanic crust of the Cocos plate subducts under the Caribbean plate, and to the south, where the northern part of the Nazca plate collides with the South American plate. This plate tectonic setting forms the framework on which local structural and sedimentary events have created a series of relatively small trench-slope and forearc basins in what is now the coastal plain and adjacent offshore area of Central and South America, south or west of a line of mountain ranges with active volcanism. Sedimentary fill is generally of Tertiary age. The basins and subbasins recognized and described include: in Ecuador - Guayas, Santa Elena, Progreso, Valdivia, Bajo Grande, Manta, Muisne-Esmeraldas, and Borbon; in Colombia - Choco-Pacific; in Panama - Gulf of Panama basin complex (Santiago, Tonosi, Sambu), and Burica-Chiriqui; in Costa Rica - Terraba and Coronado/Tempisque; in Nicaragua - San Juan del Sur; and in the Honduras, El Salvador, and Guatemala - the Pacific coastal basin.

  18. Comment on "Intermittent plate tectonics?".

    PubMed

    Korenaga, Jun

    2008-06-01

    Silver and Behn (Reports, 4 January 2008, p. 85) proposed that intermittent plate tectonics may resolve a long-standing paradox in Earth's thermal evolution. However, their analysis misses one important term, which subsequently brings their main conclusion into question. In addition, the Phanerozoic eustasy record indicates that the claimed effect of intermittency is probably weak. PMID:18535229

  19. Petroleum occurrences and plate tectonics

    SciTech Connect

    Olenin, V.B.; Sokolov, B.A.

    1983-01-01

    This paper analyzes the mechanisms of petroleum formation and petroleum accumulation proposed in recent years by some Russian and foreign investigators from the viewpoint of the new global or plate tectonics. On the basis of discussion and the facts, the authors conclude that the mechanisms proposed are in contradiction to reality and their use in practical application is at least premature.

  20. Plated wire random access memories

    NASA Technical Reports Server (NTRS)

    Gouldin, L. D.

    1975-01-01

    A program was conducted to construct 4096-work by 18-bit random access, NDRO-plated wire memory units. The memory units were subjected to comprehensive functional and environmental tests at the end-item level to verify comformance with the specified requirements. A technical description of the unit is given, along with acceptance test data sheets.

  1. Double-Plate Penetration Equations

    NASA Technical Reports Server (NTRS)

    Hayashida, K. B.; Robinson, J. H.

    2000-01-01

    This report compares seven double-plate penetration predictor equations for accuracy and effectiveness of a shield design. Three of the seven are the Johnson Space Center original, modified, and new Cour-Palais equations. The other four are the Nysmith, Lundeberg-Stern-Bristow, Burch, and Wilkinson equations. These equations, except the Wilkinson equation, were derived from test results, with the velocities ranging up to 8 km/sec. Spreadsheet software calculated the projectile diameters for various velocities for the different equations. The results were plotted on projectile diameter versus velocity graphs for the expected orbital debris impact velocities ranging from 2 to 15 km/sec. The new Cour-Palais double-plate penetration equation was compared to the modified Cour-Palais single-plate penetration equation. Then the predictions from each of the seven double-plate penetration equations were compared to each other for a chosen shield design. Finally, these results from the equations were compared with test results performed at the NASA Marshall Space Flight Center. Because the different equations predict a wide range of projectile diameters at any given velocity, it is very difficult to choose the "right" prediction equation for shield configurations other than those exactly used in the equations' development. Although developed for various materials, the penetration equations alone cannot be relied upon to accurately predict the effectiveness of a shield without using hypervelocity impact tests to verify the design.

  2. Casimir torque between nanostructured plates

    E-print Network

    R. Guérout; C. Genet; A. Lambrecht; S. Reynaud

    2015-07-30

    We investigate in detail the Casimir torque induced by quantum vacuum fluctuations between two nanostructured plates. Our calculations are based on the scattering approach and take into account the coupling between different modes induced by the shape of the surface which are neglected in any sort of proximity approximation or effective medium approach. We then present an experimental setup aiming at measuring this torque.

  3. Corrosion resistant metallic bipolar plate

    DOEpatents

    Brady, Michael P. (Oak Ridge, TN); Schneibel, Joachim H. (Knoxville, TN); Pint, Bruce A. (Knoxville, TN); Maziasz, Philip J. (Oak Ridge, TN)

    2007-05-01

    A corrosion resistant, electrically conductive component such as a bipolar plate for a PEM fuel cell includes 20 55% Cr, balance base metal such as Ni, Fe, or Co, the component having thereon a substantially external, continuous layer of chromium nitride.

  4. The seismotectonics of plate boundaries

    NASA Technical Reports Server (NTRS)

    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.

  5. Avionics Box Cold Plate Damage Prevention

    NASA Technical Reports Server (NTRS)

    Stambolian, Damon B.; Larchar, Steven W.; Henderson, Gena; Tran, Donald; Barth, Tim

    2012-01-01

    Problem Introduction: 1. Prevent Cold Plate Damage in Space Shuttle. 1a. The number of cold plate problems had increased from an average of 16.5 per/year between 1990 through 2000, to an average of 39.6 per year between 2001through 2005. 1b. Each complete set of 80 cold plates cost approximately $29 million, an average of $362,500 per cold plate. 1c It takes four months to produce a single cold plate. 2. Prevent Cold Plate Damage in Future Space Vehicles.

  6. Transition Fault and the Yakutat-Pacific-North American Triple Junction

    NASA Astrophysics Data System (ADS)

    Gulick, S. P.; Christeson, G. L.; Norton, I. O.; Pavlis, T. L.; Reece, R.; van Avendonk, H.; Worthington, L. L.

    2011-12-01

    In the Gulf of Alaska the Pacific Plate, Yakutat Terrane, and North American Plate interact in a complexly deformed zone on the continental slope near Kayak Island. This zone can be viewed as a fault-trench-trench (FTT) triple junction that can only be stable if the two trench segments are aligned. In this case the trench segments are: the deformation front along which the Pacific Plate subducts beneath North America (the Aleutian Trench) and the deformation front along which the Yakutat Terrane subducts at a more westerly direction (when compared to the Pacific subduction) beneath North America (the Pamplona Zone). These two deformation fronts are, to a first order, locally aligned. The complex member of the system is the Transition Fault which is a long-lived strike-slip fault separating the 15-30 km thick Yakutat oceanic plateau crust from the 5-7 km thick Pacific Plate crust, which is itself deforming along the north-south trending Gulf of Alaska Shear Zone (GASZ). A series of seismic reflection profiles crossing the Transition Fault allow us to examine the evolution of deformation as a function of proximity to the triple junction. East of the triple junction and the GASZ, the Transition Fault is a single near vertical strike-slip zone. Moving west to the area where the GASZ interacts with the Transition Fault, three seismic profiles show that the Fault bifurcates into a southern transpressional strand with a few 100 meters of seafloor relief and a northern strike-slip dominated strand. West of the GASZ and within the region proximal to the triple junction, two seismic lines show that the Transition Fault is expressed as a southern transpressional structure with significant amounts shortening (seafloor expression increased to ~1.8 km) and a northern dominantly strike-slip fault with minor transpression. Mapping the top of basement shows that the southern arm lies within and deforms the Pacific oceanic crust with the top of ocean crust reflection to the north elevated by ~1-3 km. The northern arm of the Transition Fault continues to lie at the boundary of the Pacific and Yakutat crust across which depth to the top of the basement changes by 4-6 km suggest that the outer strand of the Transition Fault has likely stepped southward from the primary fault due to increased convergence west of the GASZ and proximal to the triple junction. This additional transpressional deformation likely occurs within the Pacific Plate due to rheology since the Pacific crust is likely the weakest tectonic member at the triple junction. We will investigate this plate boundary deformation at the Gulf of Alaska triple junction further with improved seismic imaging and integration with gravity modeling in an effort to discuss the plate boundary reorganization that can occur during attempted subduction of buoyant crust such as the Yakutat Terrane.

  7. 76 FR 63904 - Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-14

    .... Preseason Salmon Management Schedule for 2012 ] D. Pacific Halibut Management 2012 Pacific Halibut... National Oceanic and Atmospheric Administration RIN 0648-XA761 Pacific Fishery Management Council; Public... (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The Pacific Council and its...

  8. 77 FR 51772 - Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-27

    ...0648-XC190 Pacific Fishery Management Council; Public Meetings...SUMMARY: The Pacific Fishery Management Council (Pacific Council...will be held at the Riverside Hotel, 2900 Chinden Boulevard...address: Pacific Fishery Management Council, 7700 NE...

  9. 76 FR 80890 - Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ...0648-XA895 Pacific Fishery Management Council; Public Meeting AGENCY...SUMMARY: The Pacific Fishery Management Council's (Pacific Council...Embassy Suites Portland Airport Hotel, 7900 NE 82nd Avenue, Portland...address: Pacific Fishery Management Council, 7700 NE...

  10. Global Ocean Sedimentation Patterns: Plate Tectonic History Versus Climate Change

    NASA Astrophysics Data System (ADS)

    Goswami, A.; Reynolds, E.; Olson, P.; Hinnov, L. A.; Gnanadesikan, A.

    2014-12-01

    Global sediment data (Whittaker et al., 2013) and carbonate content data (Archer, 1996) allows examination of ocean sedimentation evolution with respect to age of the underlying ocean crust (Müller et al., 2008). From these data, we construct time series of ocean sediment thickness and carbonate deposition rate for the Atlantic, Pacific, and Indian ocean basins for the past 120 Ma. These time series are unique to each basin and reflect an integrated response to plate tectonics and climate change. The goal is to parameterize ocean sedimentation tied to crustal age for paleoclimate studies. For each basin, total sediment thickness and carbonate deposition rate from 0.1 x 0.1 degree cells are binned according to basement crustal age; area-corrected moments (mean, variance, etc.) are calculated for each bin. Segmented linear fits identify trends in present-day carbonate deposition rates and changes in ocean sedimentation from 0 to 120 Ma. In the North and South Atlantic and Indian oceans, mean sediment thickness versus crustal age is well represented by three linear segments, with the slope of each segment increasing with increasing crustal age. However, the transition age between linear segments varies among the three basins. In contrast, mean sediment thickness in the North and South Pacific oceans are numerically smaller and well represented by two linear segments with slopes that decrease with increasing crustal age. These opposing trends are more consistent with the plate tectonic history of each basin being the controlling factor in sedimentation rates, rather than climate change. Unlike total sediment thickness, carbonate deposition rates decrease smoothly with crustal age in all basins, with the primary controls being ocean chemistry and water column depth.References: Archer, D., 1996, Global Biogeochem. Cycles 10, 159-174.Müller, R.D., et al., 2008, Science, 319, 1357-1362.Whittaker, J., et al., 2013, Geochem., Geophys., Geosyst. DOI: 10.1002/ggge.20181

  11. The flat to normal subduction transition study to obtain the Nazca plate morphology using high resolution seismicity data from the Nazca plate in Central Chile

    NASA Astrophysics Data System (ADS)

    Nacif, Silvina; Triep, Enrique G.; Spagnotto, Silvana L.; Aragon, Eugenio; Furlani, Renzo; Álvarez, Orlando

    2015-08-01

    Data from 45 seismological stations mostly temporary were used to obtain an accurate data set of intraslab seismicity of the Nazca subducted plate between 33°S and 35°S. The interest zone located in the transition section where the Nazca plate changes from flat slab north of ~ 33° to normal slab south of that latitude. In addition, the study region is located where the active volcanic arc appears. From a set of earthquakes which were relocated using a grid-search multiple events algorithm we obtained the plate geometry from latitudes of 33°S to 34.5°S and from 60 km to 120 km in depth. The obtained morphology shows notable similarity in its structure to Maipo Orocline revealing some possible strong connection between the overriding plate and the subducting plate. We suggest that the subducted plate at the trench has been deformed in its shape consistently with the Maipo Orocline pattern and its deformation is observed below the interface zone. Our results are consistent with van Keken et al., 2011 models, and based on this the seismicity located between 70 and 120 km is probably related with dehydration processes rather than mechanical processes. From our precise earthquake locations we observed a complete lack of intraslab seismicity below 120 km depth. This valuable finding can be used to better constrain thermal models for the subduction region of Central Chile.

  12. Is a 50 Ma Event Recorded in the Absolute Plate Motion of Africa?

    NASA Astrophysics Data System (ADS)

    Maher, S. M.; Wessel, P.; Müller, R.; Harada, Y.

    2012-12-01

    There is considerable evidence for a global plate tectonic reorganization at ~Chron 21, as suggested by observed changes in global relative plate motion (RPM). The timings of these events appear to coincide with the age of the Hawaiian Emperor Bend (HEB), i.e., ~47-50 Ma. This 120° bend has traditionally been the poster child for the fixed hotspot hypothesis, suggesting the Pacific plate underwent a change in absolute plate motion (APM) as it moved over a more or less stationary Hawaiian hotspot. However, palaeomagnetic evidence favors southward motion of the Hawaii hotspot during the Emperor stage, limiting the amount of APM change required. In the Indo-Atlantic realm, RPMs involving Africa all seem compatible with a change in Africa APM around ~50 Ma. If this global plate reorganization took place there should also be physical evidence on the Africa plate itself due to the change in Africa APM. A candidate for such evidence may be the Réunion-Mascarene bend, which exhibits many HEB-like features. However, the Réunion hotspot also created the Chagos-Laccadive ridge as it encountered (and later crossed) the Carlsberg Ridge, and the oldest Mascarene section closest to the Seychelles may be continental in origin; thus there is some uncertainty in how to interpret the geometry. Furthermore, published APM models have had difficulty modeling this abrupt change in orientation. To reexamine this problem we derived a new Africa APM model that goes back to ~65 Ma using the Hybrid Polygonal Finite Rotation Method. The modeling incorporates the geometry and ages of seamount chains on the Africa plate and their associated hotspots as suitable constraints on an Africa APM model. The present as well as earlier positions of hotspots can be adjusted to get the best fit for the model. We examine how models with or without a ~50 Ma bend satisfy the geometries and age progressions of hotspot chains on the Africa plate and how well the predictions match observed paleolatitudes.

  13. Rapid change in drift of the Australian plate records collision with Ontong Java plateau.

    PubMed

    Knesel, Kurt M; Cohen, Benjamin E; Vasconcelos, Paulo M; Thiede, David S

    2008-08-01

    The subduction of oceanic plateaux, which contain extraordinarily thick basaltic crust and are the marine counterparts of continental flood-basalt provinces, is an important factor in many current models of plate motion and provides a potential mechanism for triggering plate reorganization. To evaluate such models, it is essential to decipher the history of the collision between the largest and thickest of the world's oceanic plateaux, the Ontong Java plateau, and the Australian plate, but this has been hindered by poor constraints for the arrival of the plateau at the Melanesian trench. Here we present (40)Ar-(39)Ar geochronological data on hotspot volcanoes in eastern Australian that reveal a strong link between collision of the Greenland-sized Ontong Java plateau with the Melanesian arc and motion of the Australian plate. The new ages define a short-lived period of reduced northward plate motion between 26 and 23 Myr ago, coincident with an eastward offset in the contemporaneous tracks of seamount chains in the Tasman Sea east of Australia. These features record a brief westward deflection of the Australian plate as the plateau entered and choked the Melanesian trench 26 Myr ago. From 23 Myr ago, Australia returned to a rapid northerly trajectory at roughly the same time that southwest-directed subduction began along the Trobriand trough. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks on the Pacific plate, including the archetypal Hawaiian chain, and thus provide strong evidence that immense oceanic plateaux, like the Ontong Java, can contribute to initiating rapid change in plate boundaries and motions on a global scale. PMID:18685705

  14. Home Reef, South Pacific

    NASA Technical Reports Server (NTRS)

    2006-01-01

    In the South Pacific, south of Late Island along the Tofua volcanic arc in Tonga, a new volcanic island Home Reef is being re-born. The island is thought to have emerged after a volcanic eruption in mid-August that has also spewed large amounts of floating pumice into Tongan waters and sweeping across to Fiji about 350 km (220 miles) to the west of where the new island has formed. In 2004 a similar eruption created an ephemeral island about 0.5 by 1.5 km (0.3 by 0.9 miles) in size; it was no longer visible in an ASTER image acquired November 2005. This simulated natural color image shows the vegetation-covered stratovolcanic island of Late in the upper right. Home Reef is found in the lower left. The two bluish plumes are hot seawater that is laden with volcanic ash and chemicals; the larger one can be traced for more than 14 km (8.4 miles) to the east. The image was acquired October 10, 2006 and covers an area of 24.3 by 30.2 km. It is located at 18.9 degrees South latitude, 174.7 degrees west longitude.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 24.3 by 30.2 kilometers (15 by 18.6 miles) Location: 18.9 degrees South latitude, 174.7 degrees West longitude Orientation: North at top Image Data: ASTER bands 3, 2, and 1 Original Data Resolution: 15 meters (49.2 feet) Dates Acquired: October 4, 2006

  15. Overriding plate thickness control on subducting plate curvature

    NASA Astrophysics Data System (ADS)

    Holt, Adam F.; Buffett, Bruce A.; Becker, Thorsten W.

    2015-05-01

    Subducting plate (SP) curvature exerts a key control on the amount of bending dissipation associated with subduction, and the magnitude of the subduction-resisting bending force. However, the factors controlling the development of SP curvature are not well understood. We use numerical models to quantify the role of SP rheology on the minimum radius of curvature, Rmin. We find that Rmin depends strongly on the SP thickness when the rheology is viscous. This dependence is substantially reduced when the SP behaves plastically, in line with the lack of correlation between Rmin and SP thickness on Earth. In contrast, plasticity leads to a strong positive correlation between Rmin and the overriding plate (OP) thickness. Using an analysis of Rmin versus OP thickness, we show that such a positive correlation exists on Earth. This suggests that OP structure, in conjunction with SP plasticity, is crucial in generating slab curvature systematics on Earth.

  16. Maps, Plates, and Mount Saint Helens.

    ERIC Educational Resources Information Center

    Lary, Barbara E.; Krockover, Gerald H.

    1987-01-01

    Describes a laboratory activity on plate tectonics which focuses on the connection between plate tectonics and the different types of volcanoes. Provides questions for discussion and includes suggestions for extending the activity. (ML)

  17. Thermal plate for lithography and its components

    NASA Astrophysics Data System (ADS)

    Zhang, Cunlin; Zhou, Qingli; Cao, Shengli

    2002-09-01

    This kind of plate that has an imaging layer, comprising an admixture of (1) a resole resin, (2) a novolac resin, (3) a latent Bronsted acid (4) an infrared absorber, and (5) colorant, relates to an image recording material which can be used as a material for a lithographic printing plate. The radiation-sensitive composition is sensitive to both ultraviolet and infrared radiation. The plate is intended for digital exposure with an infrared laser with 830 nm in a computer to plate (CTP) machine. The dot density of the printing plate ranges from 2 to 98 percent, and the resolution can reach 6?. On the aspect of making printing plate these characteristics achieve acceptance criterion of printing. In addition, the level of laser energy needed to image a thermal plate is substantially higher than that needed to image today's conventional plates.

  18. Nonlinear oscillations of a fluttering plate. II.

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.

    1967-01-01

    Quasi-steady aerodynamic and von Karman large deflection plate theory equations of nonlinear oscillations of fluttering plate for single mode subsonic and sonic or coupled mode supersonic oscillations

  19. Food Guide Pyramid Becomes a Plate

    MedlinePLUS

    ... First Lady Likes the Plate First Lady Michelle Obama introduced the plate and said she will use ... family, which includes daughters Sasha and Malia. Mrs. Obama, who started the Let's Move campaign to help ...

  20. 49 CFR 230.46 - Badge plates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Gauges § 230.46 Badge plates. A metal badge plate showing the allowed steam pressure shall be attached to...

  1. 49 CFR 230.46 - Badge plates.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Gauges § 230.46 Badge plates. A metal badge plate showing the allowed steam pressure shall be attached to...

  2. 49 CFR 230.46 - Badge plates.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Gauges § 230.46 Badge plates. A metal badge plate showing the allowed steam pressure shall be attached to...

  3. 49 CFR 230.46 - Badge plates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Gauges § 230.46 Badge plates. A metal badge plate showing the allowed steam pressure shall be attached to...

  4. 49 CFR 230.46 - Badge plates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Gauges § 230.46 Badge plates. A metal badge plate showing the allowed steam pressure shall be attached to...

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

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.

    1991-01-01

    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 found in the Semi-Annual status Reports submitted regularly to NASA over the course of this project and in the publications listed.

  6. Interactive Web Interface to the Global Strain Rate Map Project

    NASA Astrophysics Data System (ADS)

    Meertens, C. M.; Estey, L.; Kreemer, C.; Holt, W.

    2004-05-01

    An interactive web interface allows users to explore the results of a global strain rate and velocity model and to compare them to other geophysical observations. The most recent model, an updated version of Kreemer et al., 2003, has 25 independent rigid plate-like regions separated by deformable boundaries covered by about 25,000 grid areas. A least-squares fit was made to 4900 geodetic velocities from 79 different geodetic studies. In addition, Quaternary fault slip rate data are used to infer geologic strain rate estimates (currently only for central Asia). Information about the style and direction of expected strain rate is inferred from the principal axes of the seismic strain rate field. The current model, as well as source data, references and an interactive map tool, are located at the International Lithosphere Program (ILP) "A Global Strain Rate Map (ILP II-8)" project website: http://www-world-strain-map.org. The purpose of the ILP GSRM project is to provide new information from this, and other investigations, that will contribute to a better understanding of continental dynamics and to the quantification of seismic hazards. A unique aspect of the GSRM interactive Java map tool is that the user can zoom in and make custom views of the model grid and results for any area of the globe selecting strain rate and style contour plots and principal axes, observed and model velocity fields in specified frames of reference, and geologic fault data. The results can be displayed with other data sets such Harvard CMT earthquake focal mechanisms, stress directions from the ILP World Stress Map Project, and topography. With the GSRM Java map tool, the user views custom maps generated by a Generic Mapping Tool (GMT) server. These interactive capabilities greatly extend what is possible to present in a published paper. A JavaScript version, using pre-constructed maps, as well as a related information site have also been created for broader education and outreach access. The GSRM map tool will be demonstrated and latest model GSRM 1.1 results, containing important new data for Asia, Iran, western Pacific, and Southern California, will be presented.

  7. Diffusion between evolving interfaces

    E-print Network

    Janne Juntunen; Juha Merikoski

    2010-11-19

    Diffusion in an evolving environment is studied by continuos-time Monte Carlo simulations. Diffusion is modelled by continuos-time random walkers on a lattice, in a dynamic environment provided by bubbles between two one-dimensional interfaces driven symmetrically towards each other. For one-dimensional random walkers constrained by the interfaces, the bubble size distribution domi- nates diffusion. For two-dimensional random walkers, it is also controlled by the topography and dynamics of the interfaces. The results of the one-dimensional case are recovered in the limit where the interfaces are strongly driven. Even with simple hard-core repulsion between the interfaces and the particles, diffusion is found to depend strongly on the details of the dynamical rules of particles close to the interfaces. Article reference: Journal of Physics: Condensed Matter 22, 465402 (2010).

  8. Asymmetric mantle dynamics in the MELT region of the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Toomey, D. R.; Wilcock, W. S. D.; Conder, J. A.; Forsyth, D. W.; Blundy, J. D.; Parmentier, E. M.; Hammond, W. C.

    2002-06-01

    The mantle electromagnetic and tomography (MELT) experiment found a surprising degree of asymmetry in the mantle beneath the fast-spreading, southern East Pacific Rise (MELT Seismic Team, Science 280 (1998) 1215-1218; Forsyth et al., Science 280 (1998) 1235-1238; Toomey et al., Science 280 (1998) 1224-1227; Wolfe and Solomon, Science 280 (1998) 1230-1232; Scheirer et al., Science 280 (1998) 1221-1224; Evans et al., Science 286 (1999) 752-756). Pressure-release melting of the upwelling mantle produces magma that migrates to the surface to form a layer of new crust at the spreading center about 6 km thick (Canales et al., Science 280 (1998) 1218-1221). Seismic and electromagnetic measurements demonstrated that the distribution of this melt in the mantle is asymmetric (Forsyth et al., Science 280 (1998) 1235-1238; Toomey et al., Science 280 (1998) 1224-1227; Evans et al., Science 286 (1999) 752-756) at depths of several tens of kilometers, melt is more abundant beneath the Pacific plate to the west of the axis than beneath the Nazca plate to the east. MELT investigators attributed the asymmetry in melt and geophysical properties to several possible factors: asymmetric flow passively driven by coupling to the faster moving Pacific plate; interactions between the spreading center and hotspots of the south Pacific; an off-axis center of dynamic upwelling; and/or anomalous melting of an embedded compositional heterogeneity (MELT Seismic Team, Science 280 (1998) 1215-1218; Forsyth et al., Science 280 (1998) 1235-1238; Toomey et al., Science 280 (1998) 1224-1227; Wolfe and Solomon, Science 280 (1998) 1230-1232; Evans et al., Science 286 (1999) 752-756). Here we demonstrate that passive flow driven by asymmetric plate motion alone is not a sufficient explanation of the anomalies. Asthenospheric flow from hotspots in the Pacific superswell region back to the migrating ridge axis in conjunction with the asymmetric plate motion can create many of the observed anomalies.

  9. Electrochemical Assay of Gold-Plating Solutions

    NASA Technical Reports Server (NTRS)

    Chiodo, R.

    1982-01-01

    Gold content of plating solution is assayed by simple method that required only ordinary electrochemical laboratory equipment and materials. Technique involves electrodeposition of gold from solution onto electrode, the weight gain of which is measured. Suitable fast assay methods are economically and practically necessary in electronics and decorative-plating industries. If gold content in plating bath is too low, poor plating may result, with consequent economic loss to user.

  10. Practical automatic Arabic license plate recognition system

    NASA Astrophysics Data System (ADS)

    Mohammad, Khader; Agaian, Sos; Saleh, Hani

    2011-02-01

    Since 1970's, the need of an automatic license plate recognition system, sometimes referred as Automatic License Plate Recognition system, has been increasing. A license plate recognition system is an automatic system that is able to recognize a license plate number, extracted from image sensors. In specific, Automatic License Plate Recognition systems are being used in conjunction with various transportation systems in application areas such as law enforcement (e.g. speed limit enforcement) and commercial usages such as parking enforcement and automatic toll payment private and public entrances, border control, theft and vandalism control. Vehicle license plate recognition has been intensively studied in many countries. Due to the different types of license plates being used, the requirement of an automatic license plate recognition system is different for each country. [License plate detection using cluster run length smoothing algorithm ].Generally, an automatic license plate localization and recognition system is made up of three modules; license plate localization, character segmentation and optical character recognition modules. This paper presents an Arabic license plate recognition system that is insensitive to character size, font, shape and orientation with extremely high accuracy rate. The proposed system is based on a combination of enhancement, license plate localization, morphological processing, and feature vector extraction using the Haar transform. The performance of the system is fast due to classification of alphabet and numerals based on the license plate organization. Experimental results for license plates of two different Arab countries show an average of 99 % successful license plate localization and recognition in a total of more than 20 different images captured from a complex outdoor environment. The results run times takes less time compared to conventional and many states of art methods.

  11. No quantum friction between uniformly moving plates

    E-print Network

    T. G. Philbin; U. Leonhardt

    2009-03-26

    The Casimir forces between two plates moving parallel to each other are found by calculating the vacuum electromagnetic stress tensor. The perpendicular force between the plates is modified by the motion but there is no lateral force on the plates. Electromagnetic vacuum fluctuations do not therefore give rise to "quantum friction" in this case, contrary to previous assertions. The result shows that the Casimir-Polder force on a particle moving at constant speed parallel to a plate also has no lateral component.

  12. Microengineered cathode interface studies

    SciTech Connect

    Kueper, T.; Doshi, R.; Krumpelt, M.

    1996-10-01

    The overpotential at the cathode/electrolyte interface has been recognized as an important limitation on the performance of solid oxide fuel cells (SOFCs). This project is an effort to gain a scientific understanding of which interface features and conditions contribute to cathode polarization in SOFCs. The paper discusses three possible rate-limiting factors in the cathode reaction. The paper studies the electronic conductivity in the electrolyte, the ionic conductivity in the cathode, cathode geometry near the interface, and cathode surface area.

  13. Multimodal neuroelectric interface development

    NASA Technical Reports Server (NTRS)

    Trejo, Leonard J.; Wheeler, Kevin R.; Jorgensen, Charles C.; Rosipal, Roman; Clanton, Sam T.; Matthews, Bryan; Hibbs, Andrew D.; Matthews, Robert; Krupka, Michael

    2003-01-01

    We are developing electromyographic and electroencephalographic methods, which draw control signals for human-computer interfaces from the human nervous system. We have made progress in four areas: 1) real-time pattern recognition algorithms for decoding sequences of forearm muscle activity associated with control gestures; 2) signal-processing strategies for computer interfaces using electroencephalogram (EEG) signals; 3) a flexible computation framework for neuroelectric interface research; and d) noncontact sensors, which measure electromyogram or EEG signals without resistive contact to the body.

  14. Turbomachine Interface Sealing

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Chupp, Raymond E.; Lattime, Scott B.; Steinetz, Bruce M.

    2005-01-01

    Sealing interfaces and coatings, like lubricants, are sacrificial, giving up their integrity for the benefit of the component. Clearance control is a major issue in power systems turbomachine design and operational life. Sealing becomes the most cost-effective way to enhance system performance. Coatings, films, and combined use of both metals and ceramics play a major role in maintaining interface clearances in turbomachine sealing and component life. This paper focuses on conventional and innovative materials and design practices for sealing interfaces.

  15. Impact Delamination and Fracture in Aluminum/Acrylic Sandwich Plates

    NASA Technical Reports Server (NTRS)

    Liaw, Benjamin; Zeichner, Glenn; Liu, Yanxiong; Bowles, Kenneth J. (Technical Monitor)

    2000-01-01

    Impact-induced delamination and fracture in 6061-T6 aluminum/cast acrylic sandwich plates adhered by epoxy were generated in an instrumented drop-weight impact machine. Although only a small dent was produced on the aluminum side when a hemispherical penetrator tup was dropped onto it from a couple of inches, a large ring of delamination at the interface was observed. The delamination damage was often accompanied by severe shattering in the acrylic substratum. Damage patterns in the acrylic layer include radial and ring cracks and, together with delamination at the interface, may cause peeling-off of acrylic material from the sandwich plate. Theory of stress-wave propagation can be used to explain these damage patterns. The impact tests were conducted at various temperatures. The results also show clearly that temperature effect is very important in impact damage. For pure cast acrylic nil-ductile transition (NDT) occurs between 185-195 F. Excessive impact energy was dissipated into fracture energy when tested at temperature below this range or through plastic deformation when tested at temperature above the NDT temperature. Results from this study will be used as baseline data for studying fiber-metal laminates, such as GLARE and ARALL for advanced aeronautical and astronautical applications.

  16. UPDATE ON MECHANICAL ANALYSIS OF MONOLITHIC FUEL PLATES

    SciTech Connect

    D. E. Burkes; F. J. Rice; J.-F. Jue; N. P. Hallinan

    2008-03-01

    Results on the relative bond strength of the fuel-clad interface in monolithic fuel plates have been presented at previous RRFM conferences. An understanding of mechanical properties of the fuel, cladding, and fuel / cladding interface has been identified as an important area of investigation and quantification for qualification of monolithic fuel forms. Significant progress has been made in the area of mechanical analysis of the monolithic fuel plates, including mechanical property determination of fuel foils, cladding processed by both hot isostatic pressing and friction bonding, and the fuel-clad composite. In addition, mechanical analysis of fabrication induced residual stress has been initiated, along with a study to address how such stress can be relieved prior to irradiation. Results of destructive examinations and mechanical tests are presented along with analysis and supporting conclusions. A brief discussion of alternative non-destructive evaluation techniques to quantify not only bond quality, but also bond integrity and strength, will also be provided. These are all necessary steps to link out-of-pile observations as a function of fabrication with in-pile behaviours.

  17. Upper plate contraction north of the migrating Mendocino triple junction northern California: Implications for partitioning of strain

    USGS Publications Warehouse

    McCrory, P.A.

    2000-01-01

    Geologic measurement of permanent contraction across the Cascadia subduction margin constrains one component of the tectonic deformation along the convergent plate boundary, the component critical for the seismic hazard assessment of crustal faults. A comprehensive survey of active faults in onshore subduction margin rocks at the southern end of the Cascadia subduction zone indicates that these thrust faults accommodate ??10 mm/yr of convergence oriented 020??-045??. Seismotectonic models of subduction zones typically assign this upper plate strain to the estimate of aseismic slip on the megathrust. Geodetic models include this permanent crustal strain within estimates of elastic strain accumulation on the megathrust. Both types of models underestimate the seismic hazard associated with crustal faults. Subtracting the observed contraction from the plate convergence rate (40-50 mm/yr; directed 040??-055??) leaves 30-40 mm/yr of convergence to be partitioned between slip on the megathrust, contraction within the southern Juan de Fuca plate, and crustal contraction outside the subduction complex rocks. This simple estimate of slip partitioning neglects the discrepancy between the plate convergence and contraction directions in the vicinity of the Mendocino triple junction. The San Andreas and Cascadia limbs of the Mendocino triple junction are not collinear. The eastern edge of the broad San Andreas boundary is ??85 km east of the Cascadia subduction boundary, and across this zone the Pacific plate converges directly with the North America plate. The skewed orientation of crustal structures just north of the leading edge of the Pacific plate suggests that they are deforming in a hybrid stress field resulting from both Juan de Fuca-North America motion and Pacific-North America motion. The composite convergence direction (50 mm/yr: directed 023??) is consistent with the compressive stress axis (020??) inferred from focal mechanisms of crustal earthquakes in the Humboldt region. Deformation in such a hybrid stress field implies that the crustal faults are being loaded from two major tectonic sources. The slip on crustal faults north of the Mendocino triple junction may consume 4-5 mm/yr of Pacific-Humboldt convergence. The remaining 17-18 mm/yr of convergence may be consumed as distributed shortening expressed in the high rates of uplift in the Cape Mendocino region or as northward translation of the continental margin, north of the triple junction.

  18. ZOOPLANKTON VOLUMES OFF THE PACIFIC COAST, 1955

    E-print Network

    Cooperative Oceanic Fisheries Investigations off the Pacific coast of California and Baja Cali- fornia during with vessels of other organizations (Pacific Oceanic Fishery Investigations of the United States Fish and V of the Pacific Ocean north of 20" north latitude. The operation has been designated "Norpac", and data collected

  19. Perspective Climate change and the tropical Pacific

    E-print Network

    of the tropical Pacific atmosphere­ocean system has been extensively studied in connection with the El Nin~o cycle variations. Ocean Heat Transports: Pacific vs. Atlantic. Oceans influence the Earth's climate by transporting in the present ocean. Pacific heat transport estimates range from 0 to 1 PW northward across 2°N and 2­3 PW south

  20. UH Parking Access & Mid-Pacific Institute

    E-print Network

    Hall Keller Hall Physical Science Building Pacific Ocean Science & Technology Kuykendall Annex44 44 Stairs Pond UH Parking Access & Mid-Pacific Institute Exit M¯anoa Innovation Center and Kau Auxiliary Services Pacific Biomedical Warehouse Agricultural Science Shops Campus Security n Landscaping

  1. UH Parking Access & Mid-Pacific Institute

    E-print Network

    Pacific Ocean Science & Technology Kuykendall Annex Information Technology Center Krauss Hall Holmes Hall44 44 Stairs Pond UH Parking Access & Mid-Pacific Institute Exit Dole Street Offices Multipurpose Portables Lincoln Hall Hale Laulima Hale Kahawai Hale Kuahine Auxiliary Services Pacific Biomedical

  2. Introduction The Pacific hake (Merluccius produc-

    E-print Network

    are with Fisheries and Oceans Canada, Pacific Biologi- cal Station, Nanaimo, BC V9T 6N7. Rebecca E. Thomas and Oceans Canada. ABSTRACT--Pacific hake, Merluccius productus, the most abundant groundfish coast, we hypothesize that the annual move- ments of Pacific hake are more responsive to climate-ocean

  3. UH Parking Access & Mid-Pacific Institute

    E-print Network

    Hall Keller Hall Physical Science Building Pacific Ocean Science & Technology Kuykendall AnnexStairs Pond UH Parking Access & Mid-Pacific Institute Exit M¯anoa Innovation Center and Kau Auxiliary Services Pacific Biomedical Warehouse Agricultural Science Shops Campus Security n Landscaping

  4. TSF Interface Package

    Energy Science and Technology Software Center (ESTSC)

    2004-03-01

    A collection of packages of classes for interfacing to sparse and dense matrices, vectors and graphs, and to linear operators. TSF (via TSFCore, TSFCoreUtils and TSFExtended) provides the application programmer interface to any number of solvers, linear algebra libraries and preconditioner packages, providing also a sophisticated technique for combining multiple packages to solve a single problem. TSF provides a collection of abstract base classes that define the interfaces to abstract vector, matrix and linear soeratormore »objects. By using abstract interfaces, users of TSF are not limiting themselves to any one concrete library and can in fact easily combine multiple libraries to solve a single problem.« less

  5. The Use of 2.4-mm Locking Plate System in Treating Comminuted Mandibular Fracture by Firearm

    PubMed Central

    Pereira, Cassiano Costa Silva; Letícia dos Santos, Pâmela; Jardim, Ellen Cristina Gaetti; Júnior, Idelmo Rangel Garcia; Shinohara, Elio Hitoshi; Araujo, Marcelo Marotta

    2012-01-01

    Maxillofacial trauma caused by firearms has considerably increased, in which the mandibular body is the site of highest incidence of firearm projectiles. In these cases, the use of titanium plates and screws allows the early restoration of form and function of the mandible with stable and predictable results. Recently, conventional plates have been extensively used to treat comminuted mandibular fractures. Nevertheless, the conventional system presents several limitations such as screw compression against the bone interface and the necessity of precise fit of plate to the bone. To overcome such drawbacks, the locking plates have emerged. The present clinical case reported the operative treatment of mandibular fracture caused by firearm projectiles with the use of locking plate. The indications, advantages, and disadvantages of this system are presented. PMID:23730424

  6. Apparatus and method for controlling plating uniformity

    DOEpatents

    Hachman Jr., John T.; Kelly, James J.; West, Alan C.

    2004-10-12

    The use of an insulating shield for improving the current distribution in an electrochemical plating bath is disclosed. Numerical analysis is used to evaluate the influence of shield shape and position on plating uniformity. Simulation results are compared to experimental data for nickel deposition from a nickel--sulfamate bath. The shield is shown to improve the average current density at a plating surface.

  7. Predicting plate velocities with mantle circulation models

    E-print Network

    Becker, Thorsten W.

    ;driving forces and resulting tractions are cal- culated first and model quality is subsequently judged the relative importance of these and the uncertainties of such models. Plate-driving forces from the mantle, and plates move from ridges to trenches. Keywords: Plate motions; driving forces; edge forces; subduction

  8. 24 CFR 3280.5 - Data plate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Data plate. 3280.5 Section 3280.5... MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS General § 3280.5 Data plate. Each manufactured home shall bear a data plate affixed in a permanent manner near the main electrical panel or other...

  9. 24 CFR 3280.5 - Data plate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Data plate. 3280.5 Section 3280.5... MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS General § 3280.5 Data plate. Each manufactured home shall bear a data plate affixed in a permanent manner near the main electrical panel or other...

  10. 24 CFR 3280.5 - Data plate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Data plate. 3280.5 Section 3280.5... MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS General § 3280.5 Data plate. Each manufactured home shall bear a data plate affixed in a permanent manner near the main electrical panel or other...

  11. 24 CFR 3280.5 - Data plate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Data plate. 3280.5 Section 3280.5... MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS General § 3280.5 Data plate. Each manufactured home shall bear a data plate affixed in a permanent manner near the main electrical panel or other...

  12. Forming Weld Lands On Metal Plates

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce

    1994-01-01

    Forming shoe pounds edge of newly inserted plate workpiece. After many passes of shoe and advances of plate, thick land builds up at edge. Workpiece heated to enable metal to flow without strain hardening. Proposed upset-forming process replaces relatively expensive, time-consuming, and wasteful process in which integral weld lands created by machining metal away from plates everywhere except at lands.

  13. 46 CFR 169.665 - Name plates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Name plates. 169.665 Section 169.665 Shipping COAST... Gross Tons § 169.665 Name plates. Each generator, motor and other major item f power equipment must be provided with a name plate indicating the manufacturer's name, its rating in volts and amperes or in...

  14. 46 CFR 169.665 - Name plates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Name plates. 169.665 Section 169.665 Shipping COAST... Gross Tons § 169.665 Name plates. Each generator, motor and other major item f power equipment must be provided with a name plate indicating the manufacturer's name, its rating in volts and amperes or in...

  15. 46 CFR 169.665 - Name plates.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Name plates. 169.665 Section 169.665 Shipping COAST... Gross Tons § 169.665 Name plates. Each generator, motor and other major item f power equipment must be provided with a name plate indicating the manufacturer's name, its rating in volts and amperes or in...

  16. 46 CFR 169.665 - Name plates.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Name plates. 169.665 Section 169.665 Shipping COAST... Gross Tons § 169.665 Name plates. Each generator, motor and other major item f power equipment must be provided with a name plate indicating the manufacturer's name, its rating in volts and amperes or in...

  17. 46 CFR 169.665 - Name plates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Name plates. 169.665 Section 169.665 Shipping COAST... Gross Tons § 169.665 Name plates. Each generator, motor and other major item f power equipment must be provided with a name plate indicating the manufacturer's name, its rating in volts and amperes or in...

  18. Evaluation of the feasibility for detecting hidden corrosion damage in multi-layer gusset plates using multiple inspection techniques

    SciTech Connect

    Cobb, Adam C.; Duffer, Charles E.; Light, Glenn M.

    2014-02-18

    Gusset plates are used to connect the members in truss bridges and they are usually inspected using calipers or conventional thickness measurement ultrasonic testing (UT) devices. The damage mechanism of particular concern in gusset plates is corrosion and the regions most susceptible to corrosion damage are on the gusset interior surface where it intersects the chord, diagonal, and vertical members from water collecting at the interfaces. For heavily loaded gusset plates, one or more shingle plates are used to reinforce the gusset plate, creating a multi-layer structure. While the areas with corrosion damage remain near the members on the gusset plate, the shingle plates cover the gusset plate and greatly limit the surface access to the gusset plate, making UT thickness measurement impractical. Because of the critical nature of the gussets, a viable inspection strategy for multi-layer gusset assemblies must be developed. The premise of this research and development effort was to develop viable, field-deployable inspection approaches for this problem area. This paper presents three separate inspection approaches: two ultrasonic-based techniques and one radiographic approach. Each of these techniques was evaluated on a mock-up specimen provided by the Federal Highway Administration (FHWA) that is representative of gusseted connection from a truss bridge.

  19. Evaluation of the feasibility for detecting hidden corrosion damage in multi-layer gusset plates using multiple inspection techniques

    NASA Astrophysics Data System (ADS)

    Cobb, Adam C.; Duffer, Charles E.; Light, Glenn M.

    2014-02-01

    Gusset plates are used to connect the members in truss bridges and they are usually inspected using calipers or conventional thickness measurement ultrasonic testing (UT) devices. The damage mechanism of particular concern in gusset plates is corrosion and the regions most susceptible to corrosion damage are on the gusset interior surface where it intersects the chord, diagonal, and vertical members from water collecting at the interfaces. For heavily loaded gusset plates, one or more shingle plates are used to reinforce the gusset plate, creating a multi-layer structure. While the areas with corrosion damage remain near the members on the gusset plate, the shingle plates cover the gusset plate and greatly limit the surface access to the gusset plate, making UT thickness measurement impractical. Because of the critical nature of the gussets, a viable inspection strategy for multi-layer gusset assemblies must be developed. The premise of this research and development effort was to develop viable, field-deployable inspection approaches for this problem area. This paper presents three separate inspection approaches: two ultrasonic-based techniques and one radiographic approach. Each of these techniques was evaluated on a mock-up specimen provided by the Federal Highway Administration (FHWA) that is representative of gusseted connection from a truss bridge.

  20. Three-dimensional dynamic laboratory models of subduction with an overriding plate and variable interplate rheology

    NASA Astrophysics Data System (ADS)

    Duarte, João C.; Schellart, Wouter P.; Cruden, Alexander R.

    2013-10-01

    Subduction zones are complex 3-D features in which one tectonic plate sinks underneath another into the deep mantle. During subduction the overriding plate (OP) remains in physical contact with the subducting plate and stresses generated at the subduction zone interface and by mantle flow force the OP to deform. We present results of 3-D dynamic laboratory models of subduction that include an OP. We introduce new interplate materials comprising homogeneous mixtures of petrolatum and paraffin oil to achieve progressive subduction. The rheology of these mixtures is characterized by measurements using a strain rate controlled rheometer. The results show that the strength of the mixture increases with petrolatum content, which can be used as a proxy for the degree of mechanical coupling along the subduction interface. Results of subduction experiments are presented with different degrees of mechanical coupling and the influence this has on the dynamics and kinematics of subduction. The modelling results show that variations in the degree of mechanical coupling between the plates have a major impact on subduction velocities, slab geometry and the rate of OP deformation. In all experiments the OP is displaced following trench migration and experiences overall extension localized in the plate interior. This suggests that OP deformation is driven primarily by the toroidal component of subduction-related mantle return flow. The subduction rate is always very slow in experiments with medium mechanical coupling, and subduction stops prematurely in experiments with very high coupling. This implies that the shear forces along the plate interface in natural subduction zone systems must be relatively low and do not vary significantly. Otherwise a higher variability in natural subduction velocities should be observed for mature, non-perturbed subduction zones. The required low shear force is likely controlled by the rheology of highly hydrated sedimentary and basaltic rocks.

  1. Plate tectonics from VLBI and SLR global data

    NASA Technical Reports Server (NTRS)

    Harrison, Christopher G. A.; Robaudo, Stefano

    1992-01-01

    This study is based on data derived from fifteen years of observations of the SLR (side-looking radar) network and six years of the VLBI (very long baseline interferometry) network. In order to use all available information VLBI and SLR global data sets were combined in a least squares fashion to calculate station horizontal velocities. All significant data pertaining to a single site contribute to the station horizontal motion. The only constraint on the solution is that no vertical motion is allowed. This restriction does not greatly affect the precision of the overall solution given the fact that the expected vertical motion for most stations, even those experiencing post glacial uplift, is well under 1 cm/yr. Since the average baseline is under 4,000 km, only a small fraction of the station vertical velocity is translated into baseline rates so that the error introduced in the solution by restricting up-down station movement is minimal. As a reference, station velocities were then compared to the ones predicted by the NUVEL-1 geological model of DeMets et al. (1990). The focus of the study is on analyzing these discrepancies for global plate tectonics as well as regional tectonic settings. The method used also allows us not only to derive horizontal motion for individual stations but also to calculate Euler vectors for those plates that have enough stations located on the stable interior like North America, Pacific, Eurasia, and Australia.

  2. Plate motions and deformations from geologic and geodetic data

    NASA Technical Reports Server (NTRS)

    Jordan, Thomas H.

    1989-01-01

    The very long baseline interferometry (VLBI) measurements made in the western U.S. since 1979 provide discrete samples of the temporal and spatial deformation field. The interpretation of the VLBI derived rates of deformation requires an examination of geologic information and more densely sampled ground based geodetic data. Triangulation and trilateration data measured on two regional networks, one in the central Mojave Desert and one in the Coast Ranges east of the San Andreas fault, were processed. At the spatial scales spanned by these local geodetic networks, auxiliary geologic and geophysical data were utilized to examine the relation between measured incremental strain and the accommodation of strain seen in local geologic structures, strain release in earthquakes, and principal stress directions inferred from in situ measurements. VLBI data was also processed from stations distributed across the Pacific-North America plate boundary zone in the western U.S. The VLBI data were used to constrain the integrated rate of deformation across portions of the continental plate boundary in California and to provide a tectonic framework to interpret regional geodetic and geologic studies.

  3. Fossil slabs attached to unsubducted fragments of the Farallon plate

    PubMed Central

    Wang, Yun; Forsyth, Donald W.; Rau, Christina J.; Carriero, Nina; Schmandt, Brandon; Gaherty, James B.; Savage, Brian

    2013-01-01

    As the Pacific–Farallon spreading center approached North America, the Farallon plate fragmented into a number of small plates. Some of the microplate fragments ceased subducting before the spreading center reached the trench. Most tectonic models have assumed that the subducting oceanic slab detached from these microplates close to the trench, but recent seismic tomography studies have revealed a high-velocity anomaly beneath Baja California that appears to be a fossil slab still attached to the Guadalupe and Magdalena microplates. Here, using surface wave tomography, we establish the lateral extent of this fossil slab and show that it is correlated with the distribution of high-Mg andesites thought to derive from partial melting of the subducted oceanic crust. We also reinterpret the high seismic velocity anomaly beneath the southern central valley of California as another fossil slab extending to a depth of 200 km or more that is attached to the former Monterey microplate. The existence of these fossil slabs may force a reexamination of models of the tectonic evolution of western North America over the last 30 My. PMID:23509274

  4. Syncytial-Type Cell Plates

    PubMed Central

    Otegui, Marisa; Staehelin, L. Andrew

    2000-01-01

    Cell wall formation in the syncytial endosperm of Arabidopsis was studied by using high-pressure-frozen/freeze-substituted developing seeds and immunocytochemical techniques. The endosperm cellularization process begins at the late globular embryo stage with the synchronous organization of small clusters of oppositely oriented microtubules (?10 microtubules in each set) into phragmoplast-like structures termed mini-phragmoplasts between both sister and nonsister nuclei. These mini-phragmoplasts produce a novel kind of cell plate, the syncytial-type cell plate, from Golgi-derived vesicles ?63 nm in diameter, which fuse by way of hourglass-shaped intermediates into wide (?45 nm in diameter) tubules. These wide tubules quickly become coated and surrounded by a ribosome-excluding matrix; as they grow, they branch and fuse with each other to form wide tubular networks. The mini-phragmoplasts formed between a given pair of nuclei produce aligned tubular networks that grow centrifugally until they merge into a coherent wide tubular network with the mini-phragmoplasts positioned along the network margins. The individual wide tubular networks expand laterally until they meet and eventually fuse with each other at the sites of the future cell corners. Transformation of the wide tubular networks into noncoated, thin (?27 nm in diameter) tubular networks begins at multiple sites and coincides with the appearance of clathrin-coated budding structures. After fusion with the syncytial cell wall, the thin tubular networks are converted into fenestrated sheets and cell walls. Immunolabeling experiments show that the cell plates and cell walls of the endosperm differ from those of the embryo and maternal tissue in two features: their xyloglucans lack terminal fucose residues on the side chain, and callose persists in the cell walls after the cell plates fuse with the parental plasma membrane. The lack of terminal fucose residues on xyloglucans suggests that these cell wall matrix molecules serve both structural and storage functions. PMID:10852938

  5. Electroless metal plating of plastics

    DOEpatents

    Krause, L.J.

    1982-09-20

    Process for plating main group metals on aromatic polymers is carried out by the use of a nonaqueous solution of a salt of an alkali metal in a positive valence state and a main group metal in a negative valence state with contact between the solution and polymer providing a redox reaction causing the deposition of the main group metal and the reduction of the polymer. Products from the process exhibit useful decorative and electrical properties.

  6. Electroless metal plating of plastics

    DOEpatents

    Krause, Lawrence J. (Chicago, IL)

    1984-01-01

    Process for plating main group metals on aromatic polymers is carried out by the use of a nonaqueous solution of a salt of an alkali metal in a positive valence state and a main group metal in a negative valence state with contact between the solution and polymer providing a redox reaction causing the deposition of the main group metal and the reduction of the polymer. Products from the process exhibit useful decorative and electrical properties.

  7. Electroless metal plating of plastics

    DOEpatents

    Krause, Lawrence J. (Chicago, IL)

    1986-01-01

    Process for plating main group metals on aromatic polymers is carried out by the use of a nonaqueous solution of a salt of an alkali metal in a positive valence state and a main group metal in a negative valence state with contact between the solution and polymer providing a redox reaction causing the deposition of the main group metal and the reduction of the polymer. Products from the process exhibit useful decorative and electrical properties.

  8. A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored

    E-print Network

    Cerveny, Vlastislav

    A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries November 2001; accepted 15 November 2001 Abstract We developed a plate tectonic model for the Paleozoic rates and major tectonic and magmatic events. Plates were constructed through time by adding

  9. CENOZOIC PLATE TECTONICS OF SE ASIA 11 Cenozoic plate tectonic reconstructions of SE Asia

    E-print Network

    Royal Holloway, University of London

    CENOZOIC PLATE TECTONICS OF SE ASIA 11 Cenozoic plate tectonic reconstructions of SE Asia ROBERT TW20 0EX, UK (e-mail: robert.hall@gl.rhul.ac.uk) Abstract: A new plate tectonic model to present regional tectonics. Plate tectonic reconstructions of SE Asia may help in understanding

  10. Episodic plate tectonics on Venus

    NASA Technical Reports Server (NTRS)

    Turcotte, Donald

    1992-01-01

    Studies of impact craters on Venus from the Magellan images have placed important constraints on surface volcanism. Some 840 impact craters have been identified with diameters ranging from 2 to 280 km. Correlations of this impact flux with craters on the Moon, Earth, and Mars indicate a mean surface age of 0.5 +/- 0.3 Ga. Another important observation is that 52 percent of the craters are slightly fractured and only 4.5 percent are embayed by lava flows. These observations led researchers to hypothesize that a pervasive resurfacing event occurred about 500 m.y. ago and that relatively little surface volcanism has occurred since. Other researchers have pointed out that a global resurfacing event that ceased about 500 MYBP is consistent with the results given by a recent study. These authors carried out a series of numerical calculations of mantle convection in Venus yielding thermal evolution results. Their model considered crustal recycling and gave rapid planetary cooling. They, in fact, suggested that prior to 500 MYBP plate tectonics was active in Venus and since 500 MYBP the lithosphere has stabilized and only hot-spot volcanism has reached the surface. We propose an alternative hypothesis for the inferred cessation of surface volcanism on Venus. We hypothesize that plate tectonics on Venus is episodic. Periods of rapid plate tectonics result in high rates of subduction that cool the interior resulting in more sluggish mantle convection.

  11. MTR plates modeling with MAIA

    SciTech Connect

    Marelle, V.; Dubois, S.; Ripert, M.; Noirot, J.

    2008-07-15

    MAIA is a thermo-mechanical code dedicated to the modeling of MTR fuel plates. The main physical phenomena modeled in the code are the cladding oxidation, the interaction between fuel and Al-matrix, the swelling due to fission products and the Al/fuel particles interaction. The creeping of the plate can be modeled in the mechanical calculation. MAIA has been validated on U-Mo dispersion fuel experiments such as IRIS 1 and 2 and FUTURE. The results are in rather good agreement with post-irradiation examinations. MAIA can also be used to calculate in-pile behavior of U{sub 3}Si{sub 2} plates as in the SHARE experiment irradiated in the SCK/Mol BR2 reactor. The main outputs given by MAIA throughout the irradiation are temperatures, cladding oxidation thickness, interaction thickness, volume fraction of meat constituents, swelling, displacements, strains and stresses. MAIA is originally a two-dimensional code but a three-dimensional version is currently under development. (author)

  12. Volcano spacing and plate rigidity

    SciTech Connect

    Brink, U. )

    1991-04-01

    In-plane stresses, which accompany the flexural deformation of the lithosphere under the load adjacent volcanoes, may govern the spacing of volcanoes in hotspot provinces. Specifically, compressive stresses in the vicinity of a volcano prevent new upwelling in this area, forcing a new volcano to develop at a minimum distance that is equal to the distance in which the radial stresses change from compressional to tensile (the inflection point). If a volcano is modeled as a point load on a thin elastic plate, then the distance to the inflection point is proportional to the thickness of the plate to the power of 3/4. Compilation of volcano spacing in seven volcanic groups in East Africa and seven volcanic groups of oceanic hotspots shows significant correlation with the elastic thickness of the plate and matches the calculated distance to the inflection point. In contrast, volcano spacing in island arcs and over subduction zones is fairly uniform and is much larger than predicted by the distance to the inflection point, reflecting differences in the geometry of the source and the upwelling areas.

  13. Pliocene eclogite exhumation at plate tectonic rates in eastern Papua New Guinea.

    PubMed

    Baldwin, Suzanne L; Monteleone, Brian D; Webb, Laura E; Fitzgerald, Paul G; Grove, Marty; Hill, E June

    2004-09-16

    As lithospheric plates are subducted, rocks are metamorphosed under high-pressure and ultrahigh-pressure conditions to produce eclogites and eclogite facies metamorphic rocks. Because chemical equilibrium is rarely fully achieved, eclogites may preserve in their distinctive mineral assemblages and textures a record of the pressures, temperatures and deformation the rock was subjected to during subduction and subsequent exhumation. Radioactive parent-daughter isotopic variations within minerals reveal the timing of these events. Here we present in situ zircon U/Pb ion microprobe data that dates the timing of eclogite facies metamorphism in eastern Papua New Guinea at 4.3 +/- 0.4 Myr ago, making this the youngest documented eclogite exposed at the Earth's surface. Eclogite exhumation from depths of approximately 75 km was extremely rapid and occurred at plate tectonic rates (cm yr(-1)). The eclogite was exhumed within a portion of the obliquely convergent Australian-Pacific plate boundary zone, in an extending region located west of the Woodlark basin sea floor spreading centre. Such rapid exhumation (> 1 cm yr(-1)) of high-pressure and, we infer, ultrahigh-pressure rocks is facilitated by extension within transient plate boundary zones associated with rapid oblique plate convergence. PMID:15372021

  14. Trench-parallel flow beneath the nazca plate from seismic anisotropy.

    PubMed

    Russo, R M; Silver, P G

    1994-02-25

    Shear-wave splitting of S and SKS phases reveals the anisotropy and strain field of the mantle beneath the subducting Nazca plate, Cocos plate, and the Caribbean region. These observations can be used to test models of mantle flow. Two-dimensional entrained mantle flow beneath the subducting Nazca slab is not consistent with the data. Rather, there is evidence for horizontal trench-parallel flow in the mantle beneath the Nazca plate along much of the Andean subduction zone. Trench-parallel flow is attributale utable to retrograde motion of the slab, the decoupling of the slab and underlying mantle, and a partial barrier to flow at depth, resulting in lateral mantle flow beneath the slab. Such flow facilitates the transfer of material from the shrinking mantle reservoir beneath the Pacific basin to the growing mantle reservoir beneath the Atlantic basin. Trenchparallel flow may explain the eastward motions of the Caribbean and Scotia sea plates, the anomalously shallow bathymetry of the eastern Nazca plate, the long-wavelength geoid high over western South America, and it may contribute to the high elevation and intense deformation of the central Andes. PMID:17831621

  15. PACIFIC SOUTHWEST Forest and Range

    E-print Network

    impressed by results of studies using large-scale color 70-mm. aerial photography to detect insect damage with the Station's forest insect research staff. He is now assigned to the Forestry Sciences Laboratory, Pacific from the 1:8,000-scale color photography. #12;I n 1964-65, the Douglas-fir tussock moth (Hemerocampa

  16. Sustainable Fisheries Management: Pacific Salmon

    USGS Publications Warehouse

    Knudsen, E. Eric; Steward, C.R.; MacDonald, Donald; Williams, J.E.

    2000-01-01

    What has happened to the salmon resource in the Pacific Northwest? Who is responsible and what can be done to reverse the decline in salmon populations? The responsibly falls on everyone involved - fishermen, resource managers and concerned citizens alike - to take the steps necessary to ensure that salmon populations make a full recovery. This collection of papers examines the state of the salmon fisheries in the Pacific Northwest. They cover existing methods and supply model approaches for alternative solutions. The editors stress the importance of input from and cooperation with all parties involved to create a viable solution. Grass roots education and participation is the key to public support - and ultimately the success - of whatever management solutions are developed. A unique and valuable scientific publication, Sustainable Fisheries Management: Pacific Salmon clearly articulates the current state of the Pacific salmon resource, describes the key features of its management, and provides important guidance on how we can make the transition towards sustainable fisheries. The solutions presented in this book provide the basis of a strategy for sustainable fisheries, requiring society and governmental agencies to establish a shared vision, common policies, and a process for collaborative management.

  17. PREL Pacific Region Language Cards.

    ERIC Educational Resources Information Center

    Pacific Region Educational Lab., Honolulu, HI.

    This collection of 10 cue cards presents English translations of common English words and expressions into 10 Pacific Region languages: Palauan, Samoan, Chamorro, Hawaiian, Carolinian, Chuukese, Pohnpeian, Marshallese, Yapese, and Kosraean. The cards translate the following: hello, good morning, good afternoon, good night, thank you, you're…

  18. Pacific Educational Research Journal, 2000.

    ERIC Educational Resources Information Center

    Berg, Kathleen, Ed.; Lai, Morris, Ed.

    2000-01-01

    This journal features theoretical, empirical, and applied research with implications for and relevance to education in the Pacific area. This volume contains: (1) "Community Perceptions of Culture and Education on Moloka'i" (Lois A. Yamauchi, William L. Greene, Katherine T. Ratliffe, and Andrea K. Ceppi); (2) "Academic Performance of Asian…

  19. Fine-scale seismic structure of the shallow volcanic crust on the East Pacific Rise at 9500

    E-print Network

    Webb, Spahr C.

    to $520 m sÀ1 at the near-axis depocenters. Our analysis demonstrates that the seismic characteristicsFine-scale seismic structure of the shallow v