block models of crustal motion in southern california constrained by gps measurements 1 we estimate slip rates on major active faults in southern california using a block model constrained by global positioning system measurements of interseismic deformation the block model includes the effects of block rotation and elastic strain accumulation consistent with a simple model of the earthquake cycle our estimates of the right lateral strike slip rate on the san andreas fault vary by at least a factor of 5 from a high of 35 9 0 5 mm yr in the carrizo plain to a low of 5 1 1 5 mm yr through the san bernadino segment shortening across the puente hills thrust and left lateral slip on the raymond hill fault are consistent with both thickening and escape tectonics in the los angeles basin discrepancies between geodetic and geologic slip rate estimates along the san andreas and san jacinto faults as well as in the eastern california shear zone may be explained by a temporal change in fault system behavior we find no substantial evidence for long term postseismic relaxation and infer that the viscosity of the lower crust upper mantle may be relatively high 1019 pa s

the 2006 2007 kuril islands great earthquake sequence the southwestern half of a 500 km long seismic gap in the central kuril island arc subduction zone experienced two great earthquakes with extensive preshock and aftershock sequences in late 2006 to early 2007 the nature of seismic coupling in the gap had been uncertain due to the limited historical record of prior large events and the presence of distinctive upper plate trench and outer rise structures relative to adjacent regions along the arc that have experienced repeated great interplate earthquakes in the last few centuries the intraplate region seaward of the seismic gap had several shallow compressional events during the preceding decades notably an m s 7 2 event on 16 march 1963 leading to speculation that the interplate fault was seismically coupled this issue was partly resolved by failure of the shallow portion of the interplate megathrust in an m w 8 3 thrust event on 15 november 2006 this event ruptured 250 km along the seismic gap just northeast of the great 1963 kuril island m w 8 5 earthquake rupture zone within minutes of the thrust event intense earthquake activity commenced beneath the outer wall of the trench seaward of the interplate rupture with the larger events having normal faulting mechanisms an unusual double band of interplate and intraplate aftershocks developed on 13 january 2007 an m w 8 1 extensional earthquake ruptured within the pacific plate beneath the seaward edge of the kuril trench this event is the third largest normal faulting earthquake seaward of a subduction zone on record and its rupture zone extended to at least 33 km depth and paralleled most of the length of the 2006 rupture the 13 january 2007 event produced stronger shaking in japan than the larger thrust event as a consequence of higher short period energy radiation from the source the great event aftershock sequences were dominated by the expected faulting geometries thrust faulting for the 2006 rupture zone and normal faulting for the 2007 rupture zone a large intraplate compressional event occurred on 15 january 2009 m w 7 4 near 45 km depth below the rupture zone of the 2007 event and in the vicinity of the 16 march 1963 compressional event the fault geometry rupture process and slip distributions of the two great events are estimated using very broadband teleseismic body and surface wave observations the occurrence of the thrust event in the shallowest portion of the interplate fault in a region with a paucity of large thrust events at greater depths suggests that the event removed most of the slip deficit on this portion of the interplate fault this great earthquake doublet demonstrates the heightened seismic hazard posed by induced intraplate faulting following large interplate thrust events future seismic failure of the remainder of the seismic gap appears viable with the northeastern region that has also experienced compressional activity seaward of the megathrust warranting particular attention

strain decoupling across the decollement in the region of large slip during the 2011 tohoku oki earthquake from anisotropy of magnetic susceptibility abstract the integrated ocean drilling program iodp expedition 343 japan trench fast drilling project jfast drilled and cored across the plate boundary decollement at site c0019 near the japan trench where large slip occurred during the 2011 tohoku oki earthquake m w 9 0 anisotropy of magnetic susceptibility ams data obtained from core samples show a striking change in magnetic fabric across the decollement in the frontal prism above the decollement the maximum ams axes display a strong preferred orientation in the northeast southwest direction with the intermediate and minimum ams axes distributed in the vertical plane in the underthrust sediments below the decollement the maximum and intermediate ams axes are subhorizontal but variable in direction and the minimum ams axes display an approximately vertical preferred orientation the ams ellipsoids for all samples have an oblate component but the ams ellipsoids of the underthrust sediments are generally less oblate than those of the frontal prism the magnetic fabric of the sediments in the prism are consistent with horizontal tectonic shortening nearly parallel to the plate convergence direction in the japan trench while that in the underthrust sediments represents a vertical uniaxial strain the magnetic fabrics of the frontal prism and underthrust sediments indicate an abrupt change in strain across the decollement at shallow depths and imply that large co seismic slip occurred along a weak plate boundary decollement that is mainly decoupled over the long term

extrusion tectonics of the okhotsk plate northeast asia based on focal mechanism geologic and lineament data faulting in the chersky range northeast asia changes from right lateral transpression between north america and eurasia to left lateral strike slip between north america and the okhotsk plate the location of the okhotsk eurasia boundary is poorly constrained available data suggest this boundary is right lateral the okhotsk plate is being compressed and extruded from between north america and eurasia resulting in high levels of microseismic activity along the southern flanks of the chersky range

imprint of the north american plate in siberia revealed by gps 1 gps observations in east siberia combined with global observations collected 1995 2002 place constraints on the geometry and motions of the eurasian north american and pacific plates in east asia by comparing velocities relative to eurasia and to north america we conclude that east siberia to the east of the cherskiy range belongs to the north american plate hypothesized for three decades but not proven because of uncertainties with the plate boundary arising from the ambiguous seismicity smaller plates in east asia such as okhotsk and amurian can neither be resolved nor excluded by the gps velocities

asymmetric dynamics at subduction zones derived from plate kinematic constraints abstract the lithospheric sinking along subduction zones is part of the mantle convection therefore computing the volume of lithosphere recycled within the mantle by subducting slabs quantifies the equivalent amount of mantle that should be displaced for the mass conservation criterion the rate of subduction is constrained by the convergence rate between upper and lower plates and the motion of the subduction hinge h that may either converge or diverge relative to the upper plate here starting from the analysis of the slab hinge kinematics we evaluate the subduction rate at 31 subduction zones worldwide useful to compute volumes of sinking lithosphere into the mantle our results show that 190 km3 yr and 88 km3 yr of lithospheric slabs are currently subducting below h divergent and h convergent subduction zones respectively we also propose supporting numerical models providing asymmetric volumes of the subducted lithosphere using the subduction rate instead of plate convergence as boundary condition furthermore h divergent subduction zones appear to be coincident with subductions having westward directed slabs whereas h convergent subduction zones are mostly compatible with those that have eastward to northeastward directed slabs on the basis of this geographical polarity our lithospheric volume estimation gives 214 km3 yr and 88 km3 yr of subducting lithosphere respectively this entails that w directed subduction zones contribute more than twice in lithospheric sinking into the mantle with respect to e to ne directed ones in accordance with the conservation of mass principle this volumetric asymmetry in the mantle suggests a displacement of 120 km3 yr of mantle material from west to east providing a constraint for global asymmetric mantle convection

geodetic imaging of plate motions slip rates and partitioning of deformation in japan 1 interseismic deformation in japan results from the combined effects of tectonic processes including rotation of crustal blocks and the earthquake cycle process of elastic strain accumulation about upper plate faults and subduction zone interfaces we use spherical linear block theory constrained by geodetic observations from densely spaced global positioning system gps stations to estimate plate motions fault slip rates and spatially variable interplate coupling on the japan kuril sagami and nankai subduction zones the reference model developed in this paper consists of 20 blocks produces a mean residual velocity magnitude of 1 84 mm yr at 950 stations and accounts for 96 of the observed interseismic deformation signal we estimate fault slip rates in excess of 15 mm yr along the niigata kobe tectonic zone and itoigawa shizuoka tectonic line through central japan confirming their hypothesized roles as major tectonic boundaries oblique convergence across the nankai trough is partitioned with 3 4 of the 30 mm yr of trench parallel motion accommodated by strike slip motion on the subduction interface and the remaining 1 4 accommodated by right lateral slip on the median tectonic line in contrast our models suggest negligible slip partitioning in eastern hokkaido where oblique slip on the japan kuril subduction interface accommodates all of the trench parallel component of relative plate motion inferred spatial variations in the rake and magnitude of slip deficit on subduction zone interfaces reflect the influences of megathrust geometry and earthquake cycle processes such as enhanced elastic strain accumulation about seismic asperities and coseismic sense fault motion indicative of silent slip events or afterslip following large earthquakes

an asperity model for fault creep and interseismic deformation in northeastern japan we explore the potential geodetic signature of mechanical stress shadows surrounding inferred major seismic asperities along the japan kurile subduction megathrust such stress shadows result from a decrease in creep rates late in the interseismic period we simplify the rupture history along this megathrust as the repeated rupture of several asperities each with its own fixed recurrence interval in our models megathrust creep throughout the interseismic period evolves according to velocity strengthening friction as opposed to common kinematic back slip models of locked or partially locked i e coupled regions of the megathrust such backslip models are usually constrained by onshore geodetic data and typically find spatially extensive and smooth estimates of plate coupling a likely consequence of model regularization necessitated by poor model resolution of course these large coupled regions could also correspond to seismogenic asperities some of which have not experienced a significant earthquake historically a subset of existing kinematic models of coupling along the japan trench particularly those that use both horizontal and vertical geodetic data have inferred a surprisingly deep 100 km locked zone along the megathrust or have called upon complex poorly constrained megathrust processes such as subduction erosion to explain the geodetic observations here we posit two scenarios for distributions of asperities on a realistic 3 d megathrust interface along the japan kurile trench off ne japan these scenarios reflect common assumptions made before and after the 2011 m w 9 tohoku oki earthquake we find that models that include two shallow m9 class asperities one corresponding to the 2011 tohoku oki earthquake and one offshore of hokkaido and associated stress shadows can explain geodetic observations of interseismic strain along the eastern halves of honshu and hokkaido specifically models including localized fault creep can explain most of the observed long term vertical subsidence in this region during the past century and thus appealing to processes such as deep locking or subduction erosion may not be required

statistical tests of additional plate boundaries from plate motion inversions we have investigated the application of the f ratio test a standard statistical technique to the results of relative plate motion inversions the method tests whether the improvement in fit of the model to the data resulting from the addition of another plate to the model is greater than that expected purely by chance this approach appears to be useful in determining whether additional plate boundaries are justified we confirm previous results favoring separate north american and south american plates with a boundary located between 30 n and the equator using chase s global relative motion data we show that in addition to separate west african and somalian plates separate west indian and australian plates with a best fitting boundary between 70 e and 90 e can be resolved these results are generally consistent with the observation that the indian plate s internal deformation extends somewhat westward of the ninetyeast ridge the relative motion pole is similar to minster and jordan s and predicts the nw se compression observed in earthquake mechanisms near the ninetyeast ridge

resolving depth dependent subduction zone viscosity and afterslip from postseismic displacements following the 2011 tohoku oki japan earthquake abstract we developed a 3 d viscoelastic finite element model of the m9 2011 tohoku oki japan earthquake capable of predicting postseismic displacements due to viscoelastic relaxation and afterslip we consider seismically inferred slab geometries associated with the pacific and philippine sea plate and a wide range of candidate viscoelastic rheologies for each case we invert for afterslip based on residual surface displacements observed gps minus that predicted due to viscoelastic relaxation to develop combined viscoelastic relaxation and afterslip models we are able to find a mechanical model that fully explains all observed geodetic on land and seafloor horizontal and vertical postseismic displacements we find that postseismic displacements are in about equal parts due to viscoelastic relaxation and afterslip but their patterns are spatially distinct accurately predicting both horizontal and vertical on land postseismic displacements requires a mantle wedge viscosity structure that is depth dependent reflecting the manner in which temperature pressure and water content influence viscosity no lateral heterogeneities within the mantle wedge viscosity structure beneath northern honshu are required westward directed postseismic seafloor displacements may be due flow via low temperature plastic creep within the lower half of a pacific lithosphere weakened by plate bending the distribution of afterslip is controlled by the location of coseismic slip from the tohoku oki and other regional historic earthquakes the paradigm by which afterslip is thought of as the dominant postseismic mechanism immediately following earthquakes with viscoelastic relaxation to follow in later years is shown to no longer be valid

gps measurements of crustal deformation in the baikal mongolia area 1994 2002 implications for current kinematics of asia 1 we present new geodetic results of crustal velocities over a large part of northern asia based on gps measurements in the baikal rift zone and mongolia spanning the 1994 2002 period we combine our results with the gps velocity field for china of wang et al 2001 and derive a consistent velocity field for most of asia we find contrasted kinematic and strain regimes in mongolia with northward velocities and n s shortening in westernmost mongolia but eastward to southeastward motion and left lateral shear for central and eastern mongolia this eastward to southeastward motion of central and eastern mongolia is accommodated by left lateral slip on the e w trending tunka bolnay and gobi altay faults 2 1 2 mm yr 1 2 6 1 0 mm yr 1 and 1 2 mm yr 1 respectively and by about 4 mm yr 1 of extension across the baikal rift zone consequently 15 of the india eurasia convergence is accommodated north of the tien shan by n s shortening combined with dextral shear in the mongolian altay and by eastward displacements along major left lateral strike slip faults in central and eastern mongolia we find a counterclockwise rotation of north and south china as a quasi rigid block around a pole north of the stanovoy belt which rules out the existence of an amurian plate as previously defined and implies 2 mm yr 1 of left lateral slip on the qinling shan fault zone

interseismic coupling and asperity distribution along the kamchatka subduction zone 1 gps measurements of interseismic horizontal surface velocities reveal the degree of kinematic coupling of the plate boundary thrust along the kamchatka subduction zone from about 51 degrees to 57 degrees n latitude inversions for the distribution of aseismic slip rate along the similar to 15 degrees nw dipping underthrust suggest a nonslipping plate interface in southern kamchatka above similar to 50 km depth along the segment that ruptured in the m w 9 1952 earthquake north of similar to 53 degrees n the subduction interface experiences significant aseismic slip consistent with the lower seismic moment release in m 8 5 earthquakes along this portion of the subduction zone the gps velocities are consistent with a boundary element forward model in which historic earthquake rupture zones are represented as locked asperities surrounded by a zero shear stress subduction interface loaded by plate convergence models in which the complete rupture zones of historic earthquakes are considered locked greatly overpredict the degree of kinematic coupling reducing the area of the locked model asperities to the central 25 area of historic rupture zones fits the data well suggesting that large earthquakes involve small fully locked core asperities surrounded by conditionally stable portions of the plate interface areas of low aseismic slip rate appear to be roughly correlated with areas of low isostatic gravity anomalies over offshore forearc basins while less coupled portions of the kamchatka subduction zone coincide with high gravity anomalies offshore of two peninsulas possibly related to the subduction of the emperor meji seamount chain and the kruzenstern fracture zone

geodetic slip model of the 2011 m9 0 tohoku earthquake 1 the three dimensional crustal displacement field as sampled by gps is used to determine the coseismic slip of the 2011 m9 0 tohoku earthquake we employ a spherically layered earth structure and use a combination of onland gps out to 4000 km from the rupture and offshore gps which samples the high slip region on the interplate boundary along the japan trench inversion of the displacement field for dip slip assuming an interplate boundary of variable dip and striking 195 yields a compact slip maximum of about 33 m located 200 km east of sendai the geodetic moment is 4 06 1022 n m corresponding to mw 9 0 the area of maximum slip is concentrated at a depth of about 10 km is updip of the rupture areas of the m 7 miyagi oki earthquakes of 1933 1936 1937 and 1978 and roughly coincides with the rupture area of the m7 1 1981 miyagi oki earthquake the overlap of the 2011 slip area with several preceding ruptures suggests that the same asperities may rupture repeatedly with m 7 events within several decades of one another

full interseismic locking of the nankai and japan west kurile subduction zones an analysis of uniform elastic strain accumulation in japan constrained by permanent gps we analyze permanent global positioning system gps data obtained over japan between 1995 and 1997 to estimate the instantaneous interseismic coupling ratio of the seismogenic zones due to the subduction of the pacific and philippine sea plates below the japanese islands we first derive the gps strain rate fields that characterize the crustal deformation of southern and northern japan and invert them to determine the effective subduction velocity along the central nankai trough on one side and the japan west kurile trench on the other these reference free velocities are close to those predicted by plate motion models with respect to eurasia we conclude that the eurasian reference frame gives a good approximation to the subduction motion and that to first order both subduction zones were fully locked during the period of measurements we then test whether the coupling ratio shows local variations within the seismogenic zones to do this we divide the subduction interface into 35 km 30 km elements that we model by point source groups and we invert the gps velocity field referenced to eurasia to derive the coupling ratio between 0 and 1 on each fault element the results are coherent over the 3 years and confirm that both the central nankai and the japan west kurile seismogenic zones are homogeneously fully locked most of the coupling ratios are close to 1 and a few are close to 0 intermediate values are rare the zones of decoupling correspond either to strong postseismic afterslip associated with the 1994 sanriku oki interplate earthquake japan trench or to a small overestimation of the actual lower limit of the locked zone we conclude that within the resolution of the gps data and the model 1 partial coupling did not exist during these 3 years along the nankai and japan west kurile trenches 2 the small seismic coupling ratio previously derived from earthquakes analysis for the japan and kurile trenches may indicate that a significant part of the elastic energy is dissipated silently through slow earthquakes and postseismic afterslip and 3 the heterogeneous coseismic slip pattern observed for the large and great earthquakes that rupture both subduction zones is in great contrast to the homogeneous loading finally we discuss the nonelastic residual deformation within the frame of the long term deformation of the japanese islands

dissipation of fast strike slip faulting within and beyond northeastern tibet structural patterns global positioning system gps velocities and quaternary fault slip rates in northeastern tibet indicate a transfer of left lateral slip from the kunlun fault northeast to the haiyuan fault and minor crustal shortening and rotation within a 200 km wide stepover zone related deformation also continues at least a few hundred kilometers north of the haiyuan fault into a region of diffuse extensional shear or rotation underlain by average thickness crust fast localized slip along the central kunlun fault transforms into distributed deformation across a 500 km wide zone where the lower crust is weak the distribution of fault parallel gps velocities across this region suggests a decrease in fault slip toward eastern fault tips and progressive dissipation of slip to the north rather than east of the tibetan plateau as previously suggested

ancient subduction zone in sakhalin island abstract the northern part of sakhalin island is an area of recent intensive tectonic movements and hydrothermal processes as well as a place of accumulation of useful minerals the deep structure of the lithosphere beneath the region of the neftegorsk earthquake of may 27 1995 in north sakhalin which killed residents and caused significant destruction is examined in this paper our geodynamic model shows that north sakhalin consists of the north sakhalin basin deryugin basin and an ophiolite complex located between them the deryugin basin was formed in place of an ancient deep trench after subducting the okhotsk sea plate under sakhalin in the late cretaceous paleogene the north sakhalin basin was formed on the side of the back arc basin at that time the ophiolite complex is fixed in the position of ancient subduction zone that was active in the late cretaceous paleogene approximately in the miocene the subduction of the okhotsk lithosphere apparently ceased the remains of the subduction zone in the form of an ophiolite complex have been identified from geological and geophysical data on the surface the subduction zone is manifested as deep faults stretched along sakhalin it is probable that the neftegorsk earthquake was a result of activation of this ancient subduction zone

tsunami geomorphology erosion and deposition from the 15 november 2006 kuril island tsunami the 15 november 2006 kuril earthquake mw 8 1 8 4 and tsunami enabled us to collect a compelling data set of coastal geomorphic change in the kuril islands from 3 months before to 9 and 21 months after the tsunami our pre tsunami and post tsunami surveys of the islands including four topographic profi les measured in 2006 and reoccupied in 2007 allow us the confi dence to attribute many changes to the tsunami in spite of an absence of eyewitness accounts in the central islands areas with low runup 15 m underwent massive erosion that dramatically altered the coastline tsunami deposits roughly corresponded with the extent of tsunami runup and inundation the amount of sediment eroded by the tsunami far outweighed the amount deposited on land in all cases studied the tsunami was dominantly erosive in the kuril islands because the high relief topography of the coastline accelerated tsunami outfl ow

velocity field of around the sea of okhotsk and sea of japan regions determined from a new continuous gps network data to investigate the current crustal movements in and around the sea of okhotsk and sea of japan regions we have established a continuous gps network by the end of 1997 the network had been expanded to include 12 new stations data for the period from july 1995 to november 1997 were analyzed together with data from international gps service for geodynamics igs global stations to fix the estimated coordinates to the terrestrial reference frame the tsukuba igs station was assumed to be moving westward relative to the stable eurasian continent at 2cm yr according to heki s l996 estimate we find that 1 stations in the western margin of the sea of japan have eastward velocity vectors 2 the pole position of the okhotsk plate is located near okha which reconfirms the okhotsk micro plate 3 a plate boundary of the okhotsk and amurian plates between southen sakhalin and hokkaido is suggested

the amurian plate motion and current plate kinematics in eastern asia we use global positioning system gps velocity data to model eastern asian plate kinematics out of 15 stations in korea russia china and japan studied here three sites considered to be on the stable interior of the hypothetical amurian plate showed eastward velocities as fast as 9 10 mm yr with respect to the eurasian plate they were stationary relative to each other to within 1 mm yr and these velocity vectors together with those of a few additional sites were used to accurately determine the instantaneous angular velocity euler vector of the amurian plate the predicted movement between the amurian and the north american plates is consistent with slip vectors along the eastern margin of the japan sea and sakhalin which reduces the necessity to postulate the existence of the okhotsk plate the euler vector of the amurian plate predicts left lateral movement along its boundary with the south china block consistent with neotectonic estimates of the displacement at the qinling fault possibly the southern boundary of the amurian plate the amurian plate offers a platform for models of interseismic strain buildup in southwest japan by the philippine sea plate subduction at the nankai trough slip vectors along the baikal rift the boundary between the amurian and the eurasian plates are largely inconsistent with the gps based euler vector suggesting an intrinsic difficulty in using earthquake slip vectors in continental rift zones for such studies

earthquake recurrence and magnitude and seismic deformation of the northwestern okhotsk plate northeast russia 1 recorded seismicity from the northwestern okhotsk plate northeast asia is currently insufficient to account for the predicted slip rates along its boundaries due to plate tectonics however the magnitude frequency relationship for earthquakes from the region suggests that larger earthquakes are possible in the future and that events of mw 7 5 which should occur every 100 350 years would account for almost all the slip of the plate along its boundaries due to eurasia north america convergence we use models for seismic slip distribution along the bounding faults of okhotsk to conclude that relatively little aseismic strain release is occurring and that larger future earthquakes are likely in the region our models broadly support the idea of a single okhotsk plate with the large majority of tectonic strain released along its boundaries

interpretation of interseismic deformations and the seismic cycle associated with large subduction earthquakes abstract the deformations of the overriding and subducting plates during the seismic cycle associated with large subduction earthquakes are modelled using 2d and 3d finite element techniques a particular emphasis is put on the interseismic velocities and on the impact of the rheology of the asthenosphere the distance over which the seismic cycle perturbs significantly the velocities depends upon the ratio of the viscosity in the asthenosphere to the period of the seismic cycle and can reach several thousand km for rheological parameters deduced from the first years of deformation after the aceh earthquake for a same early postseismic velocity a burger rheology of the asthenosphere implies a smaller duration of the postseismic phase and thus smaller interseismic velocities than a maxwell rheology a low viscosity wedge lvw modifies very significantly the predicted horizontal and vertical motions in the near and middle fields in particular with a lvw the peak in vertical velocity at the end of the cycle is predicted to be no longer above the deep end of the locked section of the fault but further away above the continentward limit of the lvw the lateral viscosity variations linked to the presence at depth of the subducting slab affect substantially the results the north south interseismic compression predicted by this preliminary 2d model over more than 1500 km within the sunda block is in good agreement with the pre 2004 velocities with respect to south china inferred from gps observations in thailand malaysia and indonesia in japan before the tohoku earthquake the eastern part of northern honshu was subsiding while the western part was uplifting this transition from subsidence to uplift so far away from the trench is well fitted by the predictions from our models involving a lvw most of the results obtained here in a 2d geometry are shown to provide a good estimate of the displacements for fault segments of finite lateral extent with a 3d spherical geometry as long as the displacements during the seismic cycle are normalised by the coseismic displacement

dislocation model for aseismic crustal deformation at hollister california geodetic observations at many active plate margins reveal relatively steady aseismic motion during the time between major earthquakes we model the aseismic motion by the relative motion between several blocks that suffer frictional resistance in the upper crust frictional drag is represented by uniform dislocation on a fault surface we assume that friction occurs only on the upper brittle zone of each block boundary and that frictionless sliding occurs below this zone using a bayesian inversion procedure we invert geodetic data to determine the parameters of the block and dislocation model parameters to be estimated include the two horizontal components of velocity for each block and the dislocation rate dip angle slip angle and width of each rectangular fault patch for hollister we assume five blocks and nine rectangular fault patches rates of length change on 92 lines observed by trilateration make up the data triangulation leveling very long baseline interferometry satellite ranging and global positioning system data can also be easily included in our model our inversion procedure uses prior estimates of all block and fault parameters based on geological and seismological data the block parameters are estimated from geological observations of fault displacement rates while the widths of the fault patches are estimated from earthquake hypocentral depths we choose prior estimates of the dislocation rate to match observed creep rates the estimated block motion is well resolved by the geodetic data and agrees well with the geological estimates this suggests that the block motion is steady on time scales from 10 years to 1 m y the net motion across the san andreas calaveras fault system is 38 3 mm yr oriented s38 e thus some additional displacement possibly offshore is needed to match the rate of 56 mm yr predicted by plate tectonic models the depth of the transition from frictional to free sliding varies considerably from 0 4 km on the southern calaveras to 11 km on the central san andreas fault two segments of the san andreas north of 36 50 and south of 36 40 have the greatest potential for moderate to large earthquakes

present tectonics of the southeast of russia as seen from gps observations summary the present tectonics of northeast asia has been extensively investigated during the last 12 yr by using gps techniques nevertheless crustal velocity field of the southeast of russia near the northeastern boundaries of the hypothesized amurian microplate has not been defined yet the gps data collected between 1997 february and 2009 april at sites of the regional geodynamic network were used to estimate the recent geodynamic activity of this area the calculated gps velocities indicate almost internal between network sites and external with respect to the eurasian tectonic plate stability of the investigated region we have not found clear evidences of any notable present day tectonic activity of the central sikhote alin fault as a whole this fault is the main tectonic unit that determines the geological structure of the investigated region the obtained results speak in favour of the existence of a few separate blocks and a more sophisticated structure of the proposed amurian microplate in comparison with an indivisible plate approach

development and properties of sea ice in the coastal regime of the southeastern weddell sea from october to december 1986 a program consisting of sea ice core analysis in combination with sea ice observations was carried out from the icebreaker r v polarstern as part of the winter weddell sea project the ship operated in the central and southeastern weddell sea with interests focusing on the ice shelf front between 70 s and 77 s where a system of coastal polynyas extended for several tens to hundreds of kilometers opened and maintained despite temperatures well below freezing by offshore wind forcing three wind controlled ice formation regimes may be distinguished 1 for wind speeds 10 m s the ice cover is heavily ridged and rafted 50 and formation of granular ice predominates of the total length of cores sampled in the coastal regime 32 consisted of columnar and 35 of granular ice in addition we observed two unique ice classes along the coast platelet ice formed through consolidation of underwater ice platelets underneath the solid ice cover contributed 11 to our core samples another 22 consisted of intermediate columnar granular ice which originates under the dynamic hydrographic conditions of the near ice shelf region

a nexus of plate interaction vertical deformation of holocene wave built terraces on the kamchatsky peninsula kamchatka russia kamchatsky peninsula lies within a complex meeting place of tectonic plates in particular the orthogonal interaction of the west moving komandorsky island block with mainland kamchatka examining the holocene history of vertical deformation of marine wave built terraces along the peninsular coast we differentiated tectonic blocks undergoing uplift and tilting separated by zones of stable or subsided shorelines we analyzed 200 excavations along 30 coastal profiles and quantified vertical deformation on single profiles as well as along the coast using paleoshorelines dated with marker tephras for the past 2000 yr the average rates of vertical deformation range from about 1 to 7 mm yr uplift patterns are similar to those detected from historical leveling and from mapping of the stage 5e quaternary marine terrace ca 120 ka average vertical deformation in the holocene is highest for the shortest studied time period from ca a d 250 to 600 and it is several times faster than rates for marine oxygen isotope stage mis 5e terraces vertical displacements observed along the coast are most likely coseismic and probably have included subsidence as well as uplift events because subsidence is generally associated with erosion almost surely more prehistoric large earthquakes occurred than are recorded as topographic steps in these terraces we suggest that the distribution of coastal uplift and subsidence observed along the kamchatsky peninsula coastline is qualitatively explained by the squeezing of the kamchatsky peninsula block between the bering and okhotsk plates and the komandorsky island block

can the okhotsk plate be discriminated from the north american plate the plate geometry in northeast asia has been a long standing question with a major issue being whether the sea of okhotsk and northern japanese islands are better regarded as part of the north american plate or as a separate okhotsk plate this question has been difficult to resolve because earthquake slip vectors along the kuril and japan trenches are consistent with either pacific north america or pacific okhotsk plate motion to circumvent this difficulty we also use slip vectors of earthquakes along sakhalin island and the eastern margin of the japan sea and compare them to the predicted eurasia okhotsk and eurasia north america motions for a model with a separate okhotsk plate we invert 10 eurasia okhotsk and 255 pacific okhotsk slip vectors with pacific north america and eurasia north america nuvel 1 data alternatively for a model without an okhotsk plate those eurasia okhotsk and pacific okhotsk data are regarded as eurasia north america and pacific north america data respectively the model with an okhotsk plate fits the data better than one in which this region is treated as part of the north american plate because the improved fit exceeds that expected purely from the additional plate the data indicate that the okhotsk plate can be resolved from the north american plate the motions on the okhotsk plate s boundaries predicted by the best fitting euler vectors are generally consistent with the recent tectonics the eurasia okhotsk pole is located at northernmost sakhalin island and predicts right lateral strike slip motion on the nne striking fault plane of the may 27 1995 neftegorsk earthquake consistent with the centroid moment tensor focal mechanism and the surface faulting along the northern boundary of the okhotsk plate the north america okhotsk euler vector predicts left lateral strike slip consistent with the observed focal mechanisms on the nw boundary of the okhotsk plate the eurasia okhotsk euler vector predicts e w extension discordant with the limited focal mechanisms and geological data this misfit may imply that another plate is necessary west of the magadan region in southeast siberia but this possibility is hard to confirm without further data such as might be obtained from space based geodesy

continental deformation in asia from a combined gps solution 1 after decades of research on continental tectonics there is still no consensus on the mode of deformation of continents or on the forces that drive their deformation in asia the debate opposes edge driven block models requiring a strong lithosphere with strain localized on faults to buoyancy driven continuous models requiring a viscous lithosphere with pervasive strain discriminating between these models requires continent wide estimates of lithospheric strain rates previous efforts have relied on the resampling of heterogeneous geodetic and quaternary faulting data sets using interpolation techniques we present a new velocity field based on the rigorous combination of geodetic solutions with relatively homogeneous station spacing avoiding technique dependent biases inherent to interpolation methods we find 1 unresolvable strain rates 3 109 yr over a large part of asia with current motions well described by block or microplate rotations and 2 internal strain possibly continuous limited to high elevation areas

field survey and geological effects of the 15 november 2006 kuril tsunami in the middle kuril islands the near field expression of the tsunami produced by the 15 november 2006 kuril earthquake mw 8 1 8 4 in the middle kuril islands russia including runup of up to 20 m remained unknown until we conducted a post tsunami survey in the summer of 2007 because the earthquake occurred between summer field expeditions in 2006 and 2007 we have observations topographic profiles and photographs from three months before and nine months after the tsunami we thoroughly surveyed portions of the islands of simushir and matua and also did surveys on parts of ketoi yankicha ryponkicha and rasshua tsunami runup in the near field of the middle kuril islands over a distance of about 200 km averaged 10 m over 130 locations surveyed and was typically between 5 and 15 m local topography strongly affected inundation and somewhat affected runup higher runup generally occurred along steep protruding headlands whereas longer inundation distances occurred on lower flatter coastal plains sediment transport was ubiquitous where sediment was available deposit grain size was typically sand but ranged from mud to large boulders wherever there were sandy beaches a more or less continuous sand sheet was present on the coastal plain erosion was extensive often more extensive than deposition in both space and volume especially in areas with runup of more than 10 m the tsunami eroded the beach landward stripped vegetation created scours and trim lines cut through ridges and plucked rocks out of the coastal plain

independent active microplate tectonics of northeast asia from gps velocities and block modeling 1 independent okhotsk and amurian microplate motions are tested using velocities from 123 gps sites 80 from within the proposed okh and amu plate boundaries used to constrain the plate kinematics of northeast asia a block modeling approach is used to incorporate both rigid block rotation and near boundary elastic strain accumulation effects in a formal inversion of the gps velocities models include scenarios with and without independent okh and amu plate motion our modeling favors scenarios with independent okh and amu motion based on the application of f test statistics the independent okh plate rotates 0 231 deg myr clockwise with respect to north america about a pole located north of sakhalin the modeled amu plate rotates 0 298 deg myr counterclockwise with respect to nam about a pole located west of the magadan region the plate motion parameters of the independent plates are consistent with the kinematics inferred from earthquake focal mechanism solutions along their boundaries

robust and exploratory analysis of active mesoscale tectonic zones in japan utilizing the nationwide gps array abstract a monitoring gps array recently developed in japan can yield nationwide maps of active inland tectonic zones atzs on a mesoscale approximately 70 to several hundred kilometers in lateral extent but it has been difficult to characterize atzs in japan as they are in fact operational on multiple scales and our efforts are often hindered by various irregularities in the data the key to overcoming these problems would be to gain an insight into the available data before any precise kinematic modeling is performed with indefinite assumptions in this study horizontal velocity fields deduced from the nationwide gps array were treated with a set of techniques in robust smoothing and exploratory data analysis that brought out exceptionally powerful mesoscale atzs and made them easier to characterize the resolved atzs were then retrospectively monitored to study their regional and temporal variations using a set of approx 840 observation stations about 30 km apart for a 4 year series of fixed observation time intervals 810 days each the smoothing operation involved three steps 1 imputation of the velocity fields for the purpose of anti aliasing 2 robust smoothing of the velocity fields with the median operative and 3 visualization of deformation rate distributions in several coordinate independent parameters and post filtering the geometrical resolvability of mesoscale atzs was confirmed by calibrating the smoothing scheme against synthetic tectonic boundary models before it was applied to the case study in japan atzs in japan which are essentially visible as systematic deviations in the velocity fields on the international terrestrial reference frame itrf and as strain rate anomalies were highlighted sharply along some known tectonic zones chains of active volcanoes and areas above low seismic velocity anomalies in the crust and upper mantle all of which generally paralleled the offshore trench axes the geometrical agreements among the mapped atzs and the physical anomalies in the crust are presumably due to their common structural weakness on the mesoscale in the four main islands of japan all but 30 40 of the strain rate anomalies persisted during the entire 6 years of the case study period while the rest sporadically appeared or disappeared in a period from several months to a few years the transient shifts in the deformation rates were remarkably synchronous with some nearby major tectonic episodes large earthquakes and slow events differential plate coupling strengths along the subduction zones can also be inferred from the persistent pattern of rotational strain rate anomalies forming clockwise and counterclockwise pairs along the pacific our empirical observations suggest that the first order features of interseismic crustal deformations in japan can be characterized as collateral processes behaving in response to fluctuations of the tectonic stresses on multiple scales likely influenced by changes of plate coupling strengths on the contiguous subduction faults

investigations on physical and textural properties of arctic first year sea ice in the amundsen gulf canada november 2007 june 2008 ipy cfl system study we report sea ice temperature and bulk salinity measurements as well as textural analysis from 33 first year drift and fast ice stations sampled between november 2007 and june 2008 in the southern beaufort sea amundsen gulf canadian arctic during the international polar year circumpolar flaw lead ipy cfl system study we use this significant dataset to investigate the halo thermodynamic evolution of sea ice from growth to melt a strong desalination phase is observed over a small time window in the spring using calculated proxies of sea ice permeability brine volume fraction and of the intensity of brine convection rayleigh number we demonstrate that this phase corresponds to full depth gravity drainage initiated by a restored connectivity of the brine network with warming in the spring most stations had a textural sequence typical of arctic first year ice with granular ice overlying columnar ice unusual textural features were observed sporadically sandwiched granular ice platelet ice and draped platelet ice we suggest that turbulence in leads and double diffusion in strong brine plumes following the refreeze of cracks are plausible mechanisms for the formation of these textures

global plate velocities from the global positioning system 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 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 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 rise our pacific nazca angular velocity agrees in both rate and azimuth with nuvel 1a

vertical coherence of deformation in lithosphere in the ne margin of the tibetan plateau using gps and shear wave splitting data abstract we present 817 new sks skks shear wave splitting observations to infer the mantle deformation field in the ne margin of the tibetan plateau the obvious pattern of dense splitting measurements shows that the fast wave polarization directions are oriented along a dominant nw se in the northeastern tibetan plateau alxa block and the western margin of the ordos block and rotate to near e w in the qinling orogen weihe graben and ordos block based on a continuous surface deformation field inferred from gps observations and faults slip data we model the predicted fast axis orientations c at each location of averaged splitting observation exclusion of 32 averaged observations with larger misfits within the interior of the ordos block comparing splitting observations with predictions c produces an average misfit of 11 indicating vertical coherent of lithospheric deformation in the ne margin of the tibetan plateau however in the qinling orogen the thin lithosphere t 1 2 s and the measured fast directions are parallel to the absolute plate motion apm direction we infer that both the eastward asthenospheric flow and lithospheric left lateral shear deformation contribute to the observed anisotropy within the interior of the ordos block where has thick lithospheric root 300 km and weak anisotropy t 0 6 s the average misfit increases to 63 and vertical coherence is no longer present which suggests the rigid and stable ordos block with little deformation still remains the lithospheric root of north china craton

continuous deformation of the tibetan plateau from global positioning system data global positioning system velocities from 553 control points within the tibetan plateau and on its margins show that the present day tectonics in the plateau is best described as deformation of a continuous medium at least when averaged over distances of 100 km deformation occurs throughout the plateau interior by ese wnw extension and slightly slower nne ssw shortening relative to eurasia material within the plateau interior moves roughly eastward with speeds that increase toward the east and then flows southward around the eastern end of the himalaya crustal thickening on the northeast ern and eastern margins of the plateau occurs over a zone 400 km wide and cannot be the result of elastic strain on a single major thrust fault shortening there accommodates much of india s penetration into eurasia a description in terms of movements of rigid blocks with elastic strain associated with slip on faults between them cannot match the velocity field

arc continent collision of the aleutian komandorsky arc into kamchatka insight into quaternary tectonic segmentation through pleistocene marine terraces and morphometric analysis of fluvial drainage at the nw corner of the pacific region just south of the kamchatsky peninsula the northern tip of pacific plate subduction and associated volcanic arc interacts with the western end of the aleutian komandorsky dextral transform plate boundary and associated arc study of both holocene and pleistocene sequences of uplifted marine terraces and also of fluvial drainage patterns on the kamchatsky peninsula allows us to highlight active tectonics produced by complex plate interaction our results show that the central eastern coast of the peninsula is currently divided into four different zones consisting in uplifted blocks associated with various uplift rates in front of a fold and thrust zone to the west our main tectonic benchmark the altitude of the shoreline correlated to last interglacial maximum mis 5e yields late pleistocene uplift rates ranging from 0 2 to 2 74 mm yr one of the main active faults bounding the coastal blocks is dextral and is interpreted as a prolongation of an offshore fault of the aleutian komandorsky dextral transform plate boundary we suggest that structures on the kamchatsky peninsula accommodate a part of the transform motion but that mainly the arc continent collision of the aleutian arc against kamchatka produces a bulldozer effect on the kamchatsky peninsula

rapid slip deficit rates at the eastern margin of the tibetan plateau prior to the 2008 m w 7 9 wenchuan earthquake the longmen shan is the steepest topographic front at the india asia collision zone and the site of the mw 7 9 wenchuan earthquake here to explain the interseismic gps velocities across the greater longmen shan region we develop a boundary element model including earthquake cycle effects topography the westward dipping beichuan fault and a 20 km deep shallowly dipping detachment inferred from observed afterslip and from structural considerations previous analyses which neglected the detachment and earthquake cycle effects have found shortening rates near zero in contrast we find that interseismic gps data are consistent with a shortening rate of 5 7 1 5mm yr and maximum surface slip deficit rate of 9 5 2 5mm yr this model unifies the interpretation of geodetic deformation throughout the earthquake cycle and suggests that the longmen shan is an active fold and thrust belt with of wenchuan like recurrence intervals as short as 600 years

slip distribution of the 1963 great kurile earthquake estimated from tsunami waveforms the 1963 great kurile earthquake was an underthrust earthquake occurred in the kurile kamchatka subduction zone the slip distribution of the 1963 earthquake was estimated using 21 tsunami waveforms recorded at tide gauges along the pacific and okhotsk sea coasts the extended rupture area was divided into 24 subfaults and the slip on each subfault was determined by the tsunami waveform inversion the result shows that the largest slip amount of 2 8 m was found at the shallow part and intermediate depth of the rupture area large slip amounts were found at the shallow part of the rupture area the total seismic moment was estimated to be 3 9 1021 nm mw 8 3 the 2006 kurile earthquake occurred right next to the location of the 1963 earthquake and no seismic gap exists between the source areas of the 1963 and 2006 earthquakes

physical and biological controls on dms p dynamics in ice shelf influenced fast ice during a winter spring and a spring summer transitions we report the seasonal and vertical variations of dimethylsulfide dms and its precursor dimethylsulfoniopropionate dmsp in fast ice at cape evans mcmurdo sound antarctica during the spring summer transition in 2011 and winter spring transition in 2012 we compare the variations of dms p observed to the seasonal evolution of the ice algal biomass and of the physical properties of the ice cover with emphasis on the ice texture and brine dynamics isolated dms and dmsp maxima were found during both seasonal episodes in interior ice and corresponded to the occurrence of platelet crystals in the ice texture we show that platelet crystals formation corresponded in time and depth to the incorporation of dinoflagellates strong dmsp producers in the ice cover we also show that platelet crystals could modify the environmental stresses on algal cells and perturb the vertical redistribution of dms p concentrations we show that during the winter spring transition in 2012 the dms p profiles were strongly influenced by the development and decline of a diatom dominated bloom in the bottom ice with dmsp variations remarkably following chl a variations during the spring summer transition in 2011 the increase in brine volume fraction influencing ice permeability on warming was shown to trigger 1 an important release of dms to the under ice water through brine convection and 2 a vertical redistribution of dmsp across the ice

the assessment of chemical weathering rates within an upland catchment in north east scotland a study has been made of weathering in glendye an upland catchement of heather moorland underlain mainly by granite with some gneiss in north east scotland the concentrations of a range of elements and ions in precipitation and river water were measured over a twelve month period the total input and output of each element or ion was calculated the resulting balances show net outputs of all species except hydrogen ion large net outputs of silicon 38 5 kg ha 1 a 1 and bicarbonate 48 kg ha 1 a 1 indicate considerable chemical weathering a large net output of chloride 32 kg ha 1 a 1 indicates the importance of dry deposition of oceanic aerosols when this is allowed for the rate of output of elements due to weathering is si ca na mg k fe al these results were compared with the abundance of elements in bedrock and differential weathering ratios calculated these are compared with data from the hubbard brook study in new hampshire in both cases calcium is by far the most mobile element the relative importance of the atmosphere and of chemical weathering as sources of each element was calculated and the results compared with those of a study at wet sleddale in the lake district similar patterns emerge in both cases

current deformation rates and extrusion of the northwestern okhotsk plate northeast russia 1 northeast asia is a region of broad deformation resulting from the convergence of the eurasian eu and north american na plates part of this convergence has been suggested to be relieved by the extrusion and deformation of the okhotsk plate ok three models for the deformation of the seismically active northwestern corner of the okhotsk plate based on different modes of deformation partitioning are calculated and compared to observations from gps seismicity and geology the results suggest that this region is being extruded southeastward and deforming internally by a mixture of pure contraction smooth extrusion and rigid extrusion calculated extrusion rates are 3 5 5 mm yr comparable to estimates from geologic data and internal deformation rates are 3 0 10 9 yr 1 internal deformation may be only partially accommodated by seismicity but the short time span of seismic data leaves this subject to large uncertainty

preceding coseismic and postseismic slips of the 2011 tohoku earthquake japan 1 we estimated the spatial and temporal evolution of the preceding aseismic slip from january 2003 to january 2011 the coseismic slip of the tohoku earthquake and the postseismic slip after the earthquake based on global positioning system gps data time dependent analysis indicates aseismic slip offshore of miyagi and fukushima prefectures from 2004 associated with a series of subduction earthquakes that overlap the aseismic slip area these preceding aseismic and coseismic slip areas are centered between the centers of the coseismic and afterslip areas of the tohoku earthquake offshore of miyagi prefecture while they overlap the coseismic and afterslip areas of the tohoku earthquake off fukushima prefecture the timing of moment magnitude nine mw9 class earthquakes appears to be controlled by multiple preceding slip events smaller earthquakes and their afterslip the preceding aseismic and coseismic slip decreased the coupling rate off the tohoku coast suggesting the possibility that the preceding slip represented a precursive stage of the tohoku earthquake the afterslip of the tohoku earthquake occurred in an area where the coseismic slip was not large complementing the large coseismic slip zone the afterslip along iwate miyagi extends up to 80 km in depth and is currently the sole mechanism of strain release in this depth range the source region of the anticipated miyagi oki earthquake shows small postseismic slip after the tohoku earthquake reflecting the energy release at the time of the earthquake aftershock activity is roughly governed by an afterslip process

microfabric analysis by manual and automated stereological procedures a methodological approach to antarctic tillite fabric analysis is commonly used to infer former movement directions of diamictons however analysis techniques are typically time consuming and partly subjective stereological analysis provides an alternative for objective determination of the preferred orientation of particles the ability of manual and automated stereological procedures to determine the preferred orientation of particles 120 4000 m in tillite is assessed using core samples from mount feather mcmurdo dry valleys antarctica orthogonal sets of vertical thin sections were subjected to directed secant analysis involving the determination of the number of intersections between particle outlines and a rotating series of parallel lines the manual analysis reveals a weakly developed three dimensional tilt angle plunge of 68 this reflects the depth averaged subglacial deformational structure of the deposit because the preferred orientation signal is weak in the automated set up this signal is obscured by the effect of digitization hampering the reliable assessment of the orientation direction the study shows microfabric variability within the studied cored section that is interpreted as a shear fabric reliable macrostructural information that might constrain ice flow directions requires a larger number of randomly or systematically drawn core samples from which averaged microstructural fabrics can be derived

deep slow slip events promote seismicity in northeastern japan megathrust abstract the sliding movement between oceanic and crustal plates in subduction zones is accommodated through both earthquakes and quasi static or transient aseismic slip on northeastern japan megathrust aseismic transients known as slow slip events are suggested to precede and trigger major earthquakes in their immediate surroundings however the geodetic evidence for these episodic slow slip events as well as their link to the seismicity on neighboring locked segments of the megathrust is missing here we combine the on shore geodetic data set with seismic observations during the interseismic period of 1996 2003 and demonstrate that episodic slow slip events are prevalent across the down dip portion 30 70 km depth of the megathrust and the associated stress changes modulate the seismicity rate on the neighboring seismogenic zone consequently small to moderate size earthquakes are periodically triggered whose interaction through a domino effect might occasionally lead to major earthquakes this observation has a profound impact on the estimation of seismic hazard in the region introducing a new triggering mechanism that acts across the megathrust to the extent that has not been acknowledged before

current global plate kinematics from gps 1995 2007 with the plate consistent reference frame 1 we present the vectors of rotation of 10 major lithospheric plates estimated from continuous gps observations at 192 globally distributed stations 71 stations were selected as representing stable plate regions all days for the period 1995 0 2007 0 were included in the analysis in contrast to previous gps plate models our model is independent of international terrestrial reference frames itrf the origin of our plate consistent reference frame is the center of plate rotation cp rather than the center of mass of the entire earth s system cm as in recent versions of itrf we estimate plate rotations and cp by minimizing the misfit between the horizontal velocities predicted by the plate model and the observed gps velocities if any version of itrf is used as the reference frame the drift of the itrf origin relative to cp cannot be neglected in estimation of plate rotation vectors and plate residual station velocities the model of the plate kinematics presented here addresses the problem debated since the beginning of the space geodesy how big are disagreements between the current plate motions and the motions averaged over several million years we compare the vectors of relative plate rotations estimated here with the published vectors from gps and geologic models we also discuss the integrity of individual plates as exhibited by plate residual station velocities for seven largest plates the rms value of plate residual station velocities in stable plate interiors is 0 5 0 9 mm a this value is an upper bound on deviation of real plates from infinite stiffness

distribution of stress state in the nankai subduction zone southwest japan and a comparison with japan trench to better understand the distribution of three dimensional stress states in the nankai subduction zone southwest japan we review various stress related investigations carried out in the first and second stage expeditions of the nankai trough seismogenic zone experiment nantroseize by the integrated ocean drilling program iodp and compile the stress data overall the maximum principal stress 1 in the shallower levels 1 km below seafloor or in underlying accretionary prism with 1 becoming horizontal is also suggested at all deeper drilling sites we also make a comparison of the stress state in the hanging wall of the frontal plate interface between site c0006 in the nankai and site c0019 in the japan trench subduction zone drilled after the 2011 mw 9 0 tohoku oki earthquake in the japan trench a comparison between stress state before and after the 2011 mega earthquake shows that the stress changed from compression before the earthquake to extension after the earthquake as a result of the comparison between the nankai trough and japan trench a similar current stress state with trench parallel extension was recognized at both c0006 and c0019 sites hypothetically this may indicate that in nankai trough it is still in an early stage of the interseismic cycle of a great earthquake which occurs on the decollement and propagates to the toe around site c0006

podzolization of soils under individual tree canopies in southwestern british columbia canada abstract on burnaby mountain in the coastal rainforest of british columbia there are concentric circular belts of podzolised soils around the stems of douglas fir and western hemlock trees the most acid soils occur near each stem and soils showing the greatest contrast in chroma between the eluvial and illuvial horizons occur beneath the periphery of the canopy of each tree these circular belts of soils appear to be associated with limited flow of a very acid water from precipitation down a stem and much greater flow of less acid water from the periphery of the canopy

micro plate tectonics and kinematics in northeast asia inferred from a dense set of gps observations abstract the plate tectonics of northeast asia are very complex with diffuse and sparse seismicity in the broad plate deformation zones embedded by a number of micro plates particularly the controversial amurian plate now the increasingly dense gps networks in this area provide an important tool to investigate plate tectonic kinematics and to identify the approximate plate tectonic geometries in this paper we have processed gps data 1998 2005 collected by an extensive gps network china and south korea with more than 85 continuous sites and about 1000 campaign gps stations the kinematics of northeast asia is studied by modeling gps derived velocities with rigid block rotations and elastic deformation we find that the deformation in northeast asia can be well described by a number of rotating blocks which are independent of the eurasian plate motion with statistical significance above the 99 confidence level the tectonic boundary between the north china and amuria plates is the yin shan yan shan mountain belts with about 2 4 mm yr extension along the boundary between north china and south china the qinling dabie fault is moving left laterally at about 3 1 mm yr the amuria and south korea blocks are extending at about 1 8 mm yr the baikal rift between the amurian and eurasian plates is spreading at about 3 0 mm yr the 9 17 mm yr relative motion between the amuria and okhotsk blocks is accommodated at the east sea japan trench zone localized deformation near the qinling dabie fault and yin shan yan shan mountain belts may be elastic strain accumulation due to interseismic locking of faults

soil acid deposition interactions and their possible effects on geochemical weathering rates in british uplands an attempt is made to quantify the effects that acidic pollutant depositions of anthropogenic origins may have on long term geochemical weathering and soil acidification rates at upland locations the factors which naturally regulate geochemical weathering kinetics in such areas are summarized and the possible ways in which deposition acidity may interact with these regulatory factors are examined aspects considered include modifications to soil chemical microbiological and physical characteristics the ways in which such changes may influence the extent and pattern of mineral weathering are critically discussed

two decades of spatiotemporal variations in subduction zone coupling offshore japan spatial patterns of interplate coupling on global subduction zones can be used to guide seismic hazard assessment but estimates of coupling are often constrained using a limited temporal range of geodetic data here we analyze 19 years of geodetic observations from the geonet network to assess time dependent variations in the spatial distribution of coupling on the subduction zones offshore japan we divide the position time series into five 3 75 year epochs each decomposed into best fit velocity annual periodic signals coseismic offsets and postseismic effects following seven major earthquakes nominally interseismic velocities are interpreted in terms of a combination of tectonic block motions and earthquake cycle activity the duration of the inferred postseismic activity covaries with the linear velocity to address this trade off we assume that the nominally interseismic velocity at each station varies minimally from epoch to epoch this approach is distinct from prior time series analysis across the earthquake cycle in that position data are not detrended using preseismic velocity which inherently assumes that interseismic processes are spatially stable through time but rather the best fit velocity at each station may vary between epochs these velocities reveal significant consistency since 1996 in the spatial distribution of coupling on the nankai subduction zone with variation limited primarily to the tokai and bungo channel regions where long term slow slip events have occurred and persistently coupled regions coincident with areas that slipped during historic great earthquakes on the sagami subduction zone south of tokyo we also estimate relatively stable coupling through time on the japan kuril trench we image significant coupling variations owing to effects of the 1994 mw 7 7 sanriku oki 2003 mw 8 2 tokachi oki and 2011 mw 9 0 tohoku oki earthquakes in particular strong coupling becomes more spatially extensive following the 1994 event until 2011 coseismic sense slip precedes the tohoku oki event and coupling offshore northern honshu is reduced after the 2011 earthquake despite the occurrence of the 2003 tokachi oki earthquake persistent coupling offshore hokkaido suggests ongoing seismic hazard possibly similar to past mw 9 class earthquakes interpreted from coastal paleoseismic records this time dependent analysis of interseismic deformation illuminates rich diversity in the distribution of subduction zone coupling including spatiotemporal stability in coupling effective reduction in strongly coupled regions due to aseismic thrust sense slip events and broad changes in the distribution of coupling following major earthquakes

advantages and challenges of space borne remote sensing for volcanic explosivity index vei the 2009 eruption of sarychev peak on matua island kuril islands russia abstract the intensity is important for comparing eruptions remote sensing data allow investigators to quickly estimate volcanic explosivity index vei an indicator for the intensity of an eruption the volume of volcanic products and plume height which can be determined by satellite data are two major variables used to estimate vei sarychev peak has been one of the most active volcanoes on kuril islands most recently it repeated its violent eruptions in june 2009 the volume of volcanic products in matua island discharged from sarychev peak was estimated and there was a 0 08 km 3 difference between aster and prism dem data the plume height was estimated as high as 10 km using aster images the 2009 sarychev peak eruptions is rated as vei 3 based on the measured ejecta volume and the plume height calculated in our analysis but this did not take into account the volcanic products deposited in the sea if this volume was considered the vei should have been 4 satellite remote sensing is a powerful tool to estimate vei quickly even for a volcano on an inaccessible remote island

combining constraints from tsunami modeling and sedimentology to untangle the 1969 ozernoi and 1971 kamchatskii tsunamis 1 large tsunamigenic earthquakes occurred in 1969 mw 7 7 and 1971 mw 7 8 along the bering sea and northernmost pacific coast of kamchatka both resultant tsunamis were recorded on tide gauges but only the 1969 tsunami has cataloged observations of runup and these observations are limited and questionable we used a combination of field mapping of tsunami deposits and tsunami modeling to augment this historical record we mapped tsunami deposits above a d 1956 and 1964 volcanic ash layers along more than 200 km of shoreline however the 1969 and 1971 tsunami deposits are not distinguishable in the field the distribution of tsunami deposit elevation has two latitudinal peaks from 58 to 57 sediment runup typically ranges from 2 to 4 m decreasing to the south from 57 to 56 sediment runup typically ranges from 3 to 6 m maximum more than 10 m increasing to the south models of local runup for the 1969 and 1971 tsunamis explain most of the sediment distribution differentiate the two tsunamis in some localities and elucidate the earthquakes focal mechanisms and rupture areas

the 2000 mw 6 8 uglegorsk earthquake and regional plate boundary deformation of sakhalin from geodetic data 1 interseismic gps velocities in sakhalin indicate that the island moves to the west at 3 4 mm yr with respect to the eurasian plate which is about half of the relative eurasia north america plate convergence rate gps measurements across the central sakhalin fault system provide evidence of compressive and strike slip strain accumulation at a rate 3 mm yr coseismic vertical displacements produced by the august 4 2000 mw 6 8 uglegorsk earthquake in sakhalin were analyzed by constrained nonlinear inversion which provided evidence for a reverse faulting mechanism on an east dipping fault plane

partitioning of localized and diffuse deformation in the tibetan plateau from joint inversions of geologic and geodetic observations abstract the spatial complexity of continental deformation in the greater tibetan plateau region can be defined as the extent to which relative motion of the indian and asian plates is partitioned between localized slip on major faults and distributed deformation potency rates provide a quantitative metric for determining the magnitudes of diffuse and on fault crustal deformation which are proportional to strain rates within crustal micro plates and fault slip rates respectively we simultaneously estimate micro plate rotation rates interseismic elastic strain accumulation fault slip rates on major structures and strain rates within 24 tectonic micro plates inferred from active fault maps in the greater tibetan plateau region using quasi static block models constrained by interseismic surface velocities at 731 gps sites and 9 holocene late quaternary geologic fault slip rates the joint geodetic geologic inversion indicates that geologic slip rates are kinematically consistent with differential micro plate motions estimated left lateral slip rates on the altyn tagh west central kunlun and xianshuihe faults are relatively homogeneous along strike 11 5 10 5 and 11 mm yr respectively while segmentation of the eastern kunlun fault by the intersecting elashan and riyueshan faults results in a decreased slip rate consistent with geologic observations the fraction of total potency rate associated with intrablock strain uncorrected for observational noise ranges from 0 27 in the himalayan range block to 0 91 in the aksai chin block monte carlo simulations are used to quantify the likelihood that internal deformation is statistically distinguishable from the uncertainties in geodetic velocities these simulations indicate that internal block deformation is statistically significant only within the himalayan range front where internal deformation accounts for id 0 11 of block potency rate budget west central plateau id 0 68 ganzi yushu xianshuihe 0 58 burma 0 09 jiali 0 38 and aksai chin 0 68 blocks in the other 18 tectonic micro plates within the plateau region estimated internal block potency is not currently distinguishable from the expected contribution of observational noise to residual velocities of the total potency budget within the tibetan plateau 85 is taken up by slip on major faults with the remaining 15 accommodated by internal processes at sub block scale distinguishable from observational noise the localization of the majority of plate boundary activity is also supported by the spatial distribution of modern and historical crustal earthquakes sixty seven percent of the total moment released by earthquakes in the cmt catalog and 90 of historical moment since 1900 have been released within 25 km of the major faults included in the block model representing only 12 of the characteristic half block length scale of 215 km the localization of deformation inferred from geologic geodetic and seismic observations suggests that forces applied to tectonic micro plates drive fault system activity at the india asia collision zone over decadal to quaternary time scales

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

paleotsunamis from the central kuril islands segment of the japan kuril kamchatka subduction zone abstract paleotsunami records from the central kuril island segment of the japan kuril kamchatka subduction zone indicate that the region has been frequently inundated by tsunamis as many as 20 22 tsunami deposits are recognized on matua island for the past 3300 yr with an average tsunami recurrence interval of 150 yr and 34 36 tsunami deposits are evident on simushir island for the past 2350 yr with an average recurrence of 65 yr these intervals are short but comparable to other segments of the japan kuril kamchatka subduction zone results from all survey locations reveal shortening recurrence intervals toward the present especially for the last 600 yr indicating a possible preservation bias on simushir tsunamis at least 11 m higher than the modern tsunamis in 2006 and 2007 occurred every 300 yr on average on matua tsunamis with slightly farther inundation than the 2006 and 2007 tsunamis occurred every 215 yr while those with at least 100 m farther inland inundation occur every 750 yr our paleotsunami record almost certainly includes tsunamis that are not from great subduction zone earthquakes in the central kuril segment we expect the matua record includes volcanic tsunamis and the simushir record includes tsunamis from the southern kuril segment

vertical coherence of deformation in lithosphere in the eastern himalayan syntaxis using gps quaternary fault slip rates and shear wave splitting data we present 59 new sks skks and combine them with 69 previously published data to infer the mantle deformation field in se tibet the dense set of anisotropy measurements in the eastern himalayan syntaxis ehs are oriented along a ne sw azimuth and rotate clockwise in the surround regions we use gps measurements and geologic data to determine a continuous surface deformation field that is then used to predict shear wave spitting directions at each station comparison of splitting observations with predictions yields an average misfit of 11 7 illustrating that deformation is vertically coherent consistent with previous studies within the central ehs in areas directly surrounding the namche barwa metamorphic massif the average misfit of 11 stations increases to 60 8 and vertical coherence is no longer present the complexity of the mantle anisotropy and surface observations argues for local alteration of the strain fields here associated with recent rapid exhumation of the indian crust

on the temporal variability of the surface gulf stream and near bottom flows long 3 4 years time series of the surface gulf stream position and near bottom flow south of nova scotia support earlier findings of a barotropic semimonthly periodicity in the region a bimodal gulf stream path downstream of the new england seamount chain and a seasonal shift in the gulf stream position new results are 1 a marked reduction of the meridional shifts of the surface gulf stream when it is in its north position mode 2 the semimonthly periodicity seeming to be related at times to the mf tide the most energetic long period tide and 3 an energetic highly coherent but out of phase motion with a near 40 day period in the surface gulf stream position and near bottom flow

surface deformation of bezymianny volcano kamchatka recorded by gps the eruptions from 2005 to 2010 and long term long wavelength subsidence abstract since bezymianny volcano resumed its activity in 1956 eruptions have been frequent recently with up to 1 2 explosive events per year to investigate deformation related to this activity we installed a gps network of 8 continuous and 6 campaign stations around bezymianny the two striking observations for 2005 2010 are 1 rapid and continuous network wide subsidence between 8 and 12 mm yr which appears to affect kamnet stations more than 40 km away where we observe 4 5 mm yr of subsidence and 2 only the summit station bz09 shows slight deviations from the average motion in the north component at times of eruptions the network wide subsidence cannot be explained by tectonic deformation related to the build up of interseismic strain due to subduction of the pacific plate a first order model of surface loading by eruptive products of the kluchevskoy group of volcanoes also explains only a fraction of the subsidence however a deep sill at about 30 km under kluchevskoy that constantly discharges material fits our observations well the sill is constrained by deep seismicity which suggests 9 5 km width 12 7 km length and a 13 dip angle to the south east we infer a closing rate of 0 22 m yr which implies a volume loss of 0 027 km 3 yr 0 16 m yr and 0 019 km 3 yr considering surface loading additional stations in the near and far field are required to uniquely resolve the spatial extent and likely partitioning of this source we explain the eruption related deformation at bz09 with a very shallow reservoir likely within bezymianny s edifice at a depth between 0 25 km and 1 5 km with a volume change of 1 4 10 4 km 3 much of the material erupted at bezymianny may be sourced from deeper mid crustal reservoirs with co eruptive volume changes at or below the detection limit of the gps network installation of more sensitive instruments such as tiltmeters would allow resolving of subtle co eruptive motion

dynamic lithospheric response to megathrust and precursory seismicity features of megathrust abstract temporal variations of seismic properties in inner trench regions before and after three megathrusts with magnitudes greater than or equal to 8 8 since 2004 are investigated to understand the nature of megathrust earthquakes the seismicity was increased significantly and the fault type compositions changed after megathrusts the seismicity displays characteristic fault type dependent distribution on rupture planes the postseismic thrustal events were populated around the down dip rupture margins due to the concentration of shear stress after coseismic ruptures normal faulting earthquakes increased after the megathrusts particularly in shallow depth regions with large slips which may be associated with lithospheric rebound and development of splay faults the earthquake occurrence rate b value displays a characteristic slip dependent feature the earthquake occurrence rates decrease with the slip amount of forthcoming megathrust which may be caused by continuous accumulation of plate driven stress and tectonic loading around the future rupture planes on the slab surface the slip dependency of earthquake occurrence rates is enhanced with time until the occurrence of megathrust the level of seismicity after megathrust is inversely proportional to that before megathrust yielding comparable average seismicity over the rupture zone it was also observed that the dynamic lithospheric response is highly correlated with slip distribution on the rupture plane the tension axes of the normal faulting earthquakes for 100 days after the tohoku oki earthquake focus to an apparent pole suggesting a radial viscoelastic deformation of lithosphere the temporal changes of slip dependent b values fit well with an exponential function suggesting an exponential increase of normal stress on the locked region with time until the occurrence of the megathrust this observation suggests that the temporal variation of slip dependent b values may be useful for prediction of forthcoming megathrusts at least several tens years beforehand

analysis of the far field co seismic and post seismic responses caused by the 2011 m w 9 0 tohoku oki earthquake we analyzed the far field co seismic response of the mw 9 0 tohoku oki earthquake which occurred on march 11th 2011 at the japan trench plate boundary our analysis indicates that the far field co seismic displacement was very sensitive to the magnitude of this event and that a significant co seismic surface displacement from earthquakes in the japan trench region can be observed in eurasia only for events of mw 8 0 we also analyzed the temporal characteristics of the near field post seismic deformation caused by the afterslip and the viscoelastic relaxation following the japan earthquake next we performed a simulation to analyze the influence of the two post seismic effects previously mentioned on the far field post seismic crustal deformation the simulation results help explain the post seismic crustal deformation observed on the chinese mainland 1 5 years after the event fitting results revealed that after the mw 9 0 tohoku oki earthquake the afterslip decayed exponentially and may eventually disappear after 4 years the far field post seismic displacement in eurasia caused by the viscoelastic relaxation following this earthquake will reach the same magnitude as the co seismic displacement in approximately 10 years in addition the co and post seismic coulomb stress on several ne trending faults in the northeastern and northern regions of the chinese mainland were significantly enhanced because of the mw 9 0 earthquake especially on the yilan yitong and the dunhua mishan faults the northern section of the tan lu fault zone as well as the yalujiang and the fuyu zhaodong faults

seismicity and s wave velocity structure of the crust and the upper mantle in the baikal rift and adjacent regions abstract correlations between seismicity seismotectonic deformation std field and velocity structure of the crust and the upper mantle in the baikal rift and the adjacent areas of the siberian platform and the mongol okhotsk fold belt have been investigated the 3d s wave velocity structure up to the depths of 500 km has been modeled using a representative sample of rayleigh wave group velocity dispersion curves about 3200 paths at periods from 10 to 250 s the std pattern has been reconstructed from mechanisms of large earthquakes and is in good agreement with gps and structural data analysis of the results has shown that most of large shallow earthquakes fall in regions of low s wave velocities in the uppermost mantle western mongolia and areas of recent mountain building in southern siberia and in zones of their relatively high lateral variations northeastern flank of the baikal rift in the first case the dominant std regime is compression manifested in a mixture of thrust and strike slip deformations in the second case we observe a general predominance of extension