kinematics of the western caribbean collision of the cocos ridge and upper plate deformation subduction of the cocos plate and collision of the cocos ridge have profound effects on the kinematics of the western caribbean including crustal shortening segmentation of the overriding plate and tectonic escape of the central american fore arc cafa tectonic models of the panama region pr have ranged from a rigid block to a deforming plate boundary zone recent expansion of gps networks in panama costa rica and colombia makes it possible to constrain the kinematics of the pr we present an improved kinematic block model for the western caribbean using this improved gps network to test a suite of tectonic models describing the kinematics of this region the best fit model predicts an euler vector for the counterclockwise rotation of the cafa relative to the caribbean plate at 89 10 w 7 74 n 1 193 ma 1 which is expressed as northwest directed relative block rates of 11 3 1 0 16 5 1 1 mm a 1 from northern costa rica to guatemala this model also predicts high coupling along the nicoya and osa segments of the middle american subduction zone our models demonstrate that the pr acts as a single tectonic block the panama block with a predicted euler vector of 107 65 w 26 50 n 0 133 ma 1 this rotation manifests as northeast migration of the panama block at rates of 6 9 4 0 7 8 4 8 mm a 1 from southern costa rica to eastern panama we interpret this motion as tectonic escape from cocos ridge collision redirected by collision with the north andes block which migrates to the northwest at 12 2 1 2 mm a 1

fractal plate tectonics 1 we analyze in details the statistical significance of the claim by bird 2002 of a power law distribution of plate areas covering the earth and confirm that the power law with exponent 0 25 0 05 is the most robust and parsimonious model for all plates including the very largest plates when taking into account the constraint that the plates areas must sum up to 4 steradians we propose a general class of fragmentation models that rationalize this observation and discuss the implications for the earth dynamics and the general self organization of tectonic deformations at multiple scales

block kinematics of the pacific north america plate boundary in the southwestern united states from inversion of gps seismological and geologic data 1 the active deformation of the southwestern united states 30 41 n is represented by a finite number of rotating elastic plastic spherical caps gps derived horizontal velocities geologic fault slip rates transform fault azimuths and earthquake derived fault slip vector azimuths are inverted for block angular velocities creep on block bounding faults permanent strain rates within the blocks and the rotations of 11 published gps velocity fields into to a common north american reference frame gps velocities are considered to be a combination of rigid block rotations recoverable elastic strain rates resulting from friction on block bounding faults and nonrecoverable strain rates resulting from slip on faults within the blocks the resulting pacific north america angular velocity is similar to some published estimates and satisfies transform azimuths and one spreading rate in the gulf of california earthquake slip vectors in the gulf of california and alaska and gps velocities along coastal california and within the pacific basin published fault slip rates are satisfied except in the southern mojave desert where the motion of the mohave block relative to north america is faster than can be explained by mapped faults the largest blocks the sierra nevada great valley and the eastern basin and range show permanent strain rates after removing elastic strain of only a few nanostrain per year demonstrating approximately rigid behavior observed horizontal strain rates correlate strongly with predicted strain rates from known faults suggesting that the short term strains evident in gps velocities are largely elastic in only about 20 of the region is distributed deformation needed to match the data indicating that a plate tectonic style description of the deformation of the western united states is plausible most blocks rotate about vertical axes at approximately the same rate as the pacific relative to north america suggesting that locally spin rates are communicated from block to block arguing against both floating block and ball bearing mechanisms of block rotation the similarities of the blocks spin rates to that of the pacific suggests that the pacific strongly influences their motions through edge tractions however it is shown that the blocks cannot rotate about the pacific north america pole without spinning counter to the sense of pacific north america shear unlike some other broad plate boundaries in the western united states vertical axis rotations take up very little of the slip rate budget across the region

current block motions and strain accumulation on active faults in the caribbean the caribbean plate and its boundaries with north and south america marked by subduction and large intra arc strike slip faults are a natural laboratory for the study of strain partitioning and interseismic plate coupling in relation to large earthquakes here we use most of the available campaign and continuous gps measurements in the caribbean to derive a regional velocity field expressed in a consistent reference frame we use this velocity field as input to a kinematic model where surface velocities results from the rotation of rigid blocks bounded by locked faults accumulating interseismic strain while allowing for partial locking along the lesser antilles puerto rico and hispaniola subduction we test various block geometries guided by previous regional kinematic models and geological information on active faults our findings refine a number of previously established results in particular slip rates on the strike slip faults systems bounding the caribbean plate to the north and south and the kinematics of the gonave microplate our much improved gps velocity field in the lesser antilles compared to previous studies does not require the existence of a distinct northern lesser antilles block and excludes more than 3 mm yr of strain accumulation on the lesser antilles puerto rico subduction plate interface which appears essentially uncoupled the transition from a coupled to an uncoupled subduction coincides with a transition in the long term geological behavior of the caribbean plate margin from compressional hispaniola to extensional puerto rico and lesser antilles a characteristics shared with several other subduction systems

a viscoelastic and afterslip postseismic deformation model for the 1964 alaska earthquake 1 we developed a 3 d viscoelastic model in concert with an afterslip model to describe the postseismic deformation following the 1964 alaska earthquake our model incorporates a realistic geometry including an elastic slab with very low dip angle these geometric factors are important and require a reanalysis of the 1964 coseismic model our coseismic model differs from previous models in that the montague island splay fault extends farther along the kenai peninsula coast and as a result slip on the megathrust in that region is smaller we computed postseismic deformation models using a range of mantle viscosities with maxwell relaxation time of 1 to 50 years with a best estimate of 20 years the viscoelastic model explains most of the trenchward motion observed in the present velocity field but has little impact on cumulative 1965 to present uplifts after removing the viscoelastic response the largest residual cumulative uplifts were located downdip from areas of largest coseismic slip area and we explain them using an afterslip model constrained in space by the observed cumulative postseismic uplifts and in time by tide gauge records no single mechanism can explain both the 30 years of cumulative uplift and the present velocities but a combination of viscoelastic relaxation afterslip interseismic elastic deformation and motion of southern alaska relative to north america explains the first order features of the observations forty years after the earthquake the present day velocities contain a significant component of postseismic deformation so very long lived postseismic deformation plays an important role in the subduction zone earthquake cycle for great earthquakes

stress modulation on the san andreas fault by interseismic fault system interactions during the interseismic phase of the earthquake cycle between large earthquakes stress on faults evolves in response to elastic strain accumulation driven by tectonic plate motions because earthquake cycle processes induce non local stress changes the interseismic stress accumulation rate on one fault is influenced by the behavior of all nearby faults using a geodetically constrained block model we show that the total interseismic elastic strain field generated by fault interactions within southern california may increase stressing rates on the mojave and san bernardino sections of the san andreas fault within the big bend region by as much as 38 relative to estimates from isolated san andreas models assuming steady fault system behavior since the c e 1857 fort tejon earthquake shear stress accumulated on these sections due only to interaction with faults other than the san andreas reaches 1 mpa 3 times larger than the coseismic and postseismic stress changes induced by recent southern california earthquakes stress increases along big bend sections coincide with the greatest earthquake frequency inferred from a 1500 yr long paleoseismic record and may affect earthquake recurrence intervals within geometrically complex fault systems including the sections of the san andreas fault closest to metropolitan los angeles

fast geodetic strain rates in eastern sicily southern italy new insights into block tectonics and seismic potential in the area of the great 1693 earthquake abstract along the 500 km long sicily calabria segment of the nubia eurasia plate boundary gps data highlight a complex and debated kinematic pattern we focus on eastern sicily where the style of crustal deformation rapidly changes in the space of few tens of kilometers in southeastern sicily struck by the 1693 m w 7 4 earthquake gps measurements highlight a steep velocity gradient with 2 4 mm yr of n s shortening in 10 km changing to broader extension 3 mm yr in 60 km in northern sicily and shortening in the southern tyrrhenian sea gps data and kinematic elastic block models highlight a complex fragmentation of the sicilian domain into three tectonic blocks which move independently from nubia describing an overall clockwise rotation of this crustal domain with respect to eurasia shortening in southeastern sicily is associated with a system of high angle reverse faults resulting from tectonic inversion of extensional faults at the northern tip of the hyblean plateau extension in northern sicily occurs on a broader deformation belt developed on the former kumeta alcantara line extending west of mount etna toward the southwestern tyrrhenian sea accommodating the faster rotation of the northeastern sicily block with respect to central sicily although the seismic potential of inland faults is not negligible our results strengthen the hypothesis that the malta escarpment is the likely source of the large 1693 earthquake and tsunami the observed kinematics appears only subordinately driven by the nubia eurasia convergence and the dynamics of the mediterranean subduction system is likely playing a major role in governing block motions and active tectonics in sicily

active tectonics of the st elias orogen alaska observed with gps measurements 1 we use data from campaign and continuous gps sites in southeast and south central alaska to constrain a regional tectonic block model for the st elias orogen active tectonic deformation in the orogen is dominated by the effects of the collision of the yakutat block with southern alaska our results indicate that 37 mm yr of convergence is accommodated along a relatively narrow belt of n nw dipping thrust faults in the eastern half of the orogen with the present day deformation front running through icy bay and beneath the malaspina glacier near the bering glacier the collisional thrust fault regime transitions into a broad northwest dipping decollement as the yakutat block basement begins to subduct beneath the counterclockwise rotating elias block the location of this transition aligns with the gulf of alaska shear zone implying that the pacific plate is fragmenting in response to the yakutat collision our model indicates that the bering glacier region is undergoing internal deformation and could correspond to the final stage of offscraping and accretion of sediments from the yakutat block prior to subduction predicted block motions at the western edge of the orogen suggest that the crust is laterally escaping along the aleutian fore arc

present day crustal deformation along the philippine fault in luzon philippines abstract the philippine fault results from the oblique convergence between the philippine sea plate and the sunda block eurasian plate the fault exhibits left lateral slip and transects the philippine archipelago from the northwest corner of luzon to the southeast end of mindanao for about 1200 km to better understand fault slip behavior along the philippine fault eight gps surveys were conducted from 1996 to 2008 in the luzon region we combine the 12 yr survey mode gps data in the luzon region and continuous gps data in taiwan along with additional 15 international gnss service sites in the asia pacific region and use the gamit globk software to calculate site coordinates we then estimate the site velocity from position time series by linear regression our results show that the horizontal velocities with respect to the sunda block gradually decrease from north to south along the western luzon at rates of 85 49 mm yr in the west northwest direction this feature also implies a southward decrease of convergence rate along the manila trench significant internal deformation is observed near the philippine fault using a two dimensional elastic dislocation model and gps velocities we invert for fault geometries and back slip rates of the philippine fault the results indicate that the back slip rates on the philippine fault increase from north to south with the rates of 22 37 and 40 mm yr respectively on the northern central and southern segments the inferred long term fault slip rates of 24 40 mm yr are very close to back slip rates on locked fault segments suggesting the philippine fault is fully locked the stress tensor inversions from earthquake focal mechanisms indicate a transpressional regime in the luzon area directions of 1 axes and maximum horizontal compressive axes are between 90 and 110 consistent with major tectonic features in the philippines the high angle between 1 axes and the philippine fault in central luzon suggests a weak fault zone possibly associated with fluid pressure

a gps and modelling study of deformation in northern central america summary we use gps measurements at 37 stations in honduras and el salvador to describe active deformation of the western end of the caribbean plate between the motagua fault and central american volcanic arc all gps sites located in eastern honduras move with the caribbean plate in accord with geologic evidence for an absence of neotectonic deformation in this region relative to the caribbean plate the other stations in the study area move west to west northwest at rates that increase gradually from 3 3 0 6 mm yr 1 in central honduras to 4 1 0 6 mm yr 1 in western honduras to as high as 11 12 mm yr 1 in southern guatemala the site motions are consistent with slow westward extension that has been inferred by previous authors from the north striking grabens and earthquake focal mechanisms in this region we examine the factors that influence the regional deformation by comparing the new gps velocity field to velocity fields predicted by finite element models fems that incorporate the regional plate boundary faults and known plate motions our modelling suggests that the obliquely convergent 20 direction of caribbean north american plate motion relative to the motagua fault west of 90 w impedes the ene directed motion of the caribbean plate in southern guatemala giving rise to extension in southern guatemala and western honduras the fem predictions agree even better with the measured velocities if the plate motion west of the central american volcanic arc is forced to occur over a broad zone rather than along a single throughgoing plate boundary fault our analysis confirms key predictions of a previous numerical model for deformation in this region and also indicates that the curvature of the motagua fault causes significant along strike changes in the orientations of the principal strainrate axes in the fault borderlands in accord with earthquake focal mechanisms and conclusions reached in a recent synthesis of the structural and morphologic data from honduras poor fits of our preferred models to the velocities of gps sites near the gulf of fonseca may be an artefact of the still short gps time series in this region or the simplifying assumptions of our fems

the kinematics of a transition from subduction to strike slip an example from the central new zealand plate boundary 1 we develop a kinematic model for the transition from subduction beneath the north island new zealand to strike slip in the south island constrained by gps velocities and active fault slip data to interpret these data we use an approach that inverts the kinematic data for poles of rotation of tectonic blocks and the degree of interseismic coupling on faults in the region convergence related to the hikurangi subduction margin becomes very low offshore of the northern south island indicating that in this region the majority of the relative plate motion has been transferred onto faults within the upper plate as suggested by previous studies this result has implications for understanding the likely extent of subduction interface earthquake rupture in central new zealand easterly trending strike slip faults such as the boo boo fault are the key features that facilitate the transfer of strike slip motion from the northern south island faults further north into the southern north island and onto the hikurangi subduction thrust our results also indicate that the transition from rapid forearc rotation adjacent to the hikurangi subduction margin to a strike slip dominated plate boundary with negligible vertical axis rotation in the south island occurs via a crustal scale hinge or kink in the upper plate compatible with paleomagnetic and structural geological data despite the ongoing tectonic evolution of the central new zealand region our study highlights a remarkable consistency between data sets spanning decades gps thousands of years active faulting data and millions of years paleomagnetic data and bedrock structure

geodetic evidence for low coupling on the hellenic subduction plate interface we develop a block model for the aegean and surrounding areas constrained by global positioning system gps in order to investigate the degree of coupling on the hellenic subduction interface i e the fraction of the motion across the plate boundary accommodated by elastic strain accumulation we use previously published models and seismicity to define the geometry of the interface separating the down going nubian slab from the overriding aegean this model provides a good fit to the gps observations for the 200 000 km2 aegean block the wrms of the residual velocities is 1 4 mm yr for 80 gps velocity estimates approximately the 95 level of the gps velocity uncertainties we investigate the degree of coupling on the seismically active plate interface the hellenic trench splay fault believed to be the source of the 365 ad great crete earthquake and tsunami and the kephalonia transform fault by comparing the modeled gps residual velocity field for a range of coupling values the gps observations are almost insensitive to coupling on the kephalonia transform fault because of the vertical dip of the fault that creates interseismic deformation only close to the fault where few gps sites exist the absence of resolvable shortening of the leading edge of the aegean plate precludes coupling of more than 0 2 20 of the full nubia aegean convergence rate on the modeled plate interface because of the shallow dip of the plate interface and trench splay fault and high rate of convergence if these boundaries were fully coupled high elastic strain rates would be expected to extend well into the overriding aegean plate based on our preferred value for the degree of coupling 0 1 and assuming characteristic earthquake behavior we estimate a recurrence time for great earthquakes with slip similar to that for the 365 crete event of 5700 8300 yr consistent with the absence of subsequent great earthquakes on this segment of the subduction zone

heterogeneous plate locking in the south central chile subduction zone building up the next great earthquake abstract we use global positioning system gps velocities and kinematic finite element models fe models to infer the state of locking between the converging nazca and south america plates in south central chile 36 s 46 s and to evaluate its spatial and temporal variability gps velocities provide information on earthquake cycle deformation over the last decade in areas affected by the megathrust events of 1960 m w 9 5 and 2010 m w 8 8 our data confirm that a change in surface velocity patterns of these two seismotectonic segments can be related to their different stages in the seismic cycle accordingly the northern 2010 segment was in a final stage of interseismic loading whereas the southern 1960 segment is still in a postseismic stage and undergoes a prolonged viscoelastic mantle relaxation after correcting the signals for mantle relaxation the residual gps velocity pattern suggests that the plate interface accumulates slip deficit in a spatially and presumably temporally variable way towards the next great event though some similarity exist between locking and 1960 coseismic slip extrapolating the current decadal scale slip deficit accumulation towards the 300 yr recurrence times of giant events here does neither yield the slip distribution nor the moment magnitude of the 1960 earthquake this suggests that either the locking pattern is evolving in time to reconcile a slip deficit distribution similar to the 1960 earthquake or that some asperities are not persistent over multiple events the accumulated moment deficit since 1960 suggests that highly locked patches in the 1960 segment are already capable of producing a m 8 event if triggered to fail by stress transfer from the 2010 event

motion of continental slivers and creeping subduction in the northern andes regions of intense continental deformation termed continental slivers have been identified in chile bolivia and ecuador analyses of gps data now identify another large sliver in peru the inca sliver that is moving away from a neighbouring sliver in ecuador implying that moving continental slivers control the deformation of almost the entire andean mountain range

constraining the boundary between the sunda and andaman subduction systems evidence from the 2002 mw 7 3 northern sumatra earthquake and aftershock relocations of the 2004 and 2005 great earthquakes the 2004 m w 9 0 sumatra andaman earthquake initiated along the andaman subduction zone north of the last great sumatra earthquake along the sunda trench in 1861 during the 2005 m w 8 7 banyak islands earthquake a portion of the 1861 rupture subsequently failed the boundary between the 2004 and 2005 ruptures broadly coincides with local trench rotation and the southern edge of the andaman microplate which suggests structural control on fault segmentation aftershock relocations of the 2004 and 2005 earthquakes show little overlap and the sharp boundary between the series locates near the 2002 m w 7 3 northern sumatra earthquake we posit that these features represent the southern extent of the stable andaman microplate 50 100 km northwest of what was previously reported broadband analyses of the 2002 earthquake yield a bilateral rupture pattern that is used to model coulomb stress changes near the 2004 hypocenter to assess stress interactions along adjacent fault segments

slow slip events and strain accumulation in the guerrero gap mexico 1 global positioning system gps time series in guerrero mexico reveal the existence of large slow slip events sses at the boundary between the cocos and north american plates in this study we examined the last three sses that occurred in 2001 2002 2006 and 2009 2010 and their impact on the strain accumulation along the guerrero subduction margin gps displacements were inverted to retrieve the slip distribution during each sse and the inter sse coupling of the subduction interface the three analyzed sses have equivalent moment magnitudes of between 7 50 and 7 65 their lateral extents are variable and they all show significant slip in the guerrero seismic gap during the inter sse epochs the interplate coupling is high in the area where slow slip subsequently occurs in the guerrero gap the shallow portion of the plate interface from the trench to the coast is weakly coupled the average slip deficit accumulated in the guerrero gap over a period of 12 years which corresponds to three cycles of sse is only 1 4 of the slip deficit accumulated on both sides of the gap moreover the regions of large slip deficit coincide with the rupture areas of recent large earthquakes we conclude that the sses in the guerrero gap release a significant part of the strain accumulated during the inter sse period if large subduction thrust earthquakes occur in the guerrero gap their recurrence time is probably increased compared to adjacent regions

gps constraints on continental deformation in the armenian region and lesser caucasus abstract we present the 1998 2009 gps derived velocity field for the armenia region based on a survey mode observation network of 31 gps sites we combine our results with previous gps studies of the region to better assess the deformation of the lesser caucasus and kura basin region the results show that the kura basin and the lesser caucasus regions are two different blocks and that the main fault pambak sevan sunik between these two regions has a right lateral slip rate of 2 1 mm yr this is consistent with morphotectonic estimates and suggests a fairly constant slip rate over the last 120 300 ka the right lateral slip rate on one of the southern branch of the pambak sevan sunik fault is lower than 1 mm yr and the good agreement with a geologically estimated slip rate suggests a constant slip rate over the last 1 4 myr the sardarapat and akhurian faults experience some shortening this shortening is consistent with some independent geological estimates and shows the arabian push however nnw sse orientated faults have an extensional fault normal component instead of the expected shortening due to the arabia eurasia convergence this substantial extensive strain and the sharp azimuth change of the velocity vectors between the arabia promontory and the lesser caucasus suggest that processes other than extrusion possibly related to old subduction or delamination contribute to the geodynamics of the region

present day kinematics and fault slip rates in eastern iran derived from 11 years of gps data we analyze new gps data spanning 11 years at 92 stations in eastern iran we use these data to analyze the present day kinematics and the slip rates on most seismogenic faults in eastern iran the east lut west lut kuhbanan anar dehshir and doruneh faults are confirmed as the major faults and are found to currently slip laterally at 5 6 0 6 4 4 0 4 3 6 1 3 2 0 0 7 1 4 0 9 and 1 3 0 8 mm yr respectively slip is right lateral on the ns striking east lut west lut kuhbanan anar and dehshir faults and left lateral on the ew doruneh fault the ns faults slice the eastern iranian crust into five blocks that are moving northward at 6 13 mm yr with respect to the stable afghan crust at the eastern edge of the collision zone the collective behavior of the ns faults might thus allow the arabian promontory to impinge northward into the eurasian crust the ns faults achieve additional ns shortening by rotating counterclockwise in the horizontal plane at current rates up to 0 8 ma modeling the gps and available geological data with a block rotation model suggests that the rotations have been going on at a similar rate 1 0 4 ma over the last 12 ma we identify large strains at the tips of the rotating east lut west lut and kuhbanan faults which we suspect to be responsible for the important historical and instrumental seismicity in those zones

combined effects of eurasia sunda oblique convergence and east tibetan crustal flow on the active tectonics of burma it is widely accepted that deformation of the india sunda plate is the result of partitioned hyper oblique convergence presently sub meridian dextral strike slip faulting accommodates this india sunda motion in a buffer zone the burma platelet this wide dextral strike slip shear zone is complicated by the side effect of the tibet plateau collapse that can be described in term of crustal flow and gravity tectonics the loss of potential energy related to this plateau collapse affects most of the burmese platelet particularly in its northernmost part interaction of these two distinct geodynamic processes is recorded in the gps based regional strain field the analysis of seismic focal mechanism but also from direct geologic observations both onshore and offshore myanmar and bangladesh we propose the apparent e w shortening component of this so called partitioned hyper oblique subduction is only the effect of regional gravitational forces related to the tibet plateau collapse whereas the ns strike slip faulting accommodates the india sunda motion

diverse slow slip behavior at the hikurangi subduction margin new zealand 1 the installation of a continuous gps cgps network in new zealand since 2002 has enabled the discovery of 15 slow slip events at the hikurangi subduction margin our analysis and interpretation of the cgps data reveal a marked diversity in characteristics of slow slip events sses in the north island with durations varying from 6 days to 1 5 years equivalent moment release between mw 6 3 7 2 and recurrence intervals of repeating sses on the order of 2 years to more than 5 years the duration and magnitude characteristics of hikurangi sses appear to be related to the depth where they occur the deepest longest duration and largest sses occur at the southern hikurangi margin near the downdip limit of deep down to 40 km depth strong interseismic coupling the shallowest shortest duration smallest and most frequent sses occur at the northern and central hikurangi margin near the downdip limit of unusually shallow 10 15 km depth interseismic coupling the direction of slip on the interface in the hikurangi sses is consistent with slip partitioning at the hikurangi subduction margin we also show that moment accumulation rates on the interface for the time periods between sses are 40 higher than for the period of more than a decade averaging through the sses indicating that sses compose a major portion of the overall moment release budget of the hikurangi subduction interface

space geodetic measurement of crustal deformation in central and southern california 1984 1992 we estimate the velocity field in central and southern california using global positioning system gps observations from 1986 to 1992 and very long baseline interferometry vlbi observations from 1984 to 1991 our core network includes 12 gps sites spaced approximately 50 km apart mostly in the western transverse ranges and the coastal borderlands the precision and accuracy of the relative horizontal velocities estimated for these core stations are adequately described by a 95 confidence ellipse with a semiminor axis of approximately 2 mm yr oriented roughly north south and a semimajor axis of approximately 3 mm yr oriented east west

slip rate and locking depth from gps profiles across the southern dead sea transform 1 the dead sea transform is a major strike slip fault bounding the arabia plate and the sinai subplate on the basis of two gps campaign measurements 6 years apart at 17 sites distributed in israel and jordan complemented by israeli permanent stations we compute the present day deformation across the southern segment of the dead sea transform the wadi araba fault elastic locked fault modeling of fault parallel velocities provides a slip rate of 4 9 1 4 mm a and a best fit locking depth of 12 km this slip rate is slightly higher than previous results based only on israeli permanent gps stations data which are located west of the fault it is in good agreement with results based on offset geomorphologic and geologic features that average longer periods of time 10 ka to 1 ma projection in itrf2000 reference frame allows using our data combined with results published earlier to further study the kinematics between arabia nubia and sinai systematic combination of euler poles available in the literature in addition to our new set of data shows that a wide range of arabia sinai pole positions and angular velocities predict reasonable slip rate on the dead sea fault we highlight uncertainties of calculating such poles due to the small size of the blocks and their slow relative motion along a short and almost straight strand of the transform fault which lead to a large trade off between pole location and angular velocity

structural evolution of backthrusting in the mentawai fault zone offshore sumatran forearc 1 we present the interpretation of newly acquired high quality industry standard deep seismic reflection and swath bathymetry data to provide insight into the structural style and evolution of the mentawai fault zone mfz the mfz lies along the boundary between the accretionary wedge and the proposed continental backstop this zone exhibits arcuate ridges on the seafloor convex toward the east beneath these ridges the structures developed as landward vergent imbricated backthrusts in the inner part of the accretionary wedge and higher angle backthrusts that deformed the forearc basin sediments in the forearc high anticlines were developed due to the seaward vergent forearc high thrusts originating in the accretionary wedge the imbricated backthrusts may have initiated during the early middle miocene contemporaneously with the slide and back rotation of forearc high thrusts in the late miocene the higher angle backthrusts were initiated continuous contraction induced the frontal higher angle backthrusts and formed a fold thrust belt toward the east during the pliocene the folds and thrusts were disturbed by diapirs and mud volcanoes backthrusting and fold thrust belts developed in the mfz may explain the compressional features observed at the boundary between the accretionary wedge and continental backstop along the southern sumatra margin the backthrusts along the mfz are waning in activity and hence the risk of a large earthquake and associated tsunami at the present time should be small

comparison of the microbial community composition of pristine rock cores and technical influenced well fluids from the ketzin pilot site for co2 storage two geological formations at the co2 storage pilot site in ketzin germany were geochemically and microbiologically characterized to further evaluate changes resulting from co2 injection well fluids were collected from both stuttgart storage formation 650 m depth and exter formations 400 m depth overlying the caprock either through pump tests or downhole samplings rock samples were retrieved during a deep drilling into the exter formation and primarily comprised quartz ferrous dolomite or ankerite calcite analcime plagioclase and clay minerals as determined through x ray diffraction analyses in the rocks the total organic carbon toc which potentially contributes to microbial growth was mostly below 1000 mg kg 1 the geochemical characterization of fluids revealed significant differences in the ionic composition between both formations the microbial characterization was performed through fluorescence in situ hybridization and 16s rrna gene fingerprinting in the fluids obtained from the stuttgart formation the microbial activity was affected by the relatively high toc introduced by the organic drill mud the total cell counts were approximately 106 cells ml 1 the microbial community was characteristic of a saline deep biosphere environment enriched through increased carbon availability with sulfate reducing bacteria as the most abundant microorganisms up to 60 of total cells species belonging to halophilic halotolerant proteobacteria and firmicutes were primarily detected in exter formation rocks proteobacteria and actinobacteria were detected these data provide an explicit reference to further evaluate environmental changes and community shifts in the reservoir during co2 storage and provide information for evaluating the storage efficiency and reliability

present day kinematics of active mountain building in taiwan from gps observations during 1995 2005 1 we characterize the kinematics of modern crustal deformation in taiwan and evaluate the potential for large earthquakes by computing tectonic block motions and fault slip rates from 531 gps horizontal velocities these new gps velocity field indicates that lateral extrusion in the southern transition from collision to subduction is primarily achieved by motion along several major reverse faults and internal distortion of blocks the northern transition is characterized by asymmetric opening of the okinawa trough and collision induced rotation between the ryukyu trench and okinawa trough we suggest that the differences in style of deformation in northern and southern taiwan are a result of differences in trenchward motions between the overriding plate and forearc sliver along strike variations in basin thickness and the presence of foreland basement obstacles in central taiwan result in clockwise rotation with sinistral motion on faults and counterclockwise rotation with dextral motion on faults north and south of the obstacle respectively in eastern taiwan high slip rate of 43 mm yr on the southern longitudinal valley fault lvf is responsible for the full collision of taiwan orogeny e w syn orogenic extension in the southern central range has been inferred by our model patches with high slip rate deficits on the lvf and the chelungpu fault from our model respectively mainly correspond to the source areas of the 1951 m 7 1 longitudinal valley earthquake sequence and of the 1999 mw 7 6 chi chi earthquake

gps derived interseismic coupling on the subduction and seismic hazards in the atacama region chile the atacama region between 29 s and 25 s is located in the north central area of chile a tectonically complex transition area between north and central chile deformation in atacama is due mainly to elastic loading on the subduction interface but also to diffuse shortening in the sierras pampeanas argentina the seismicity of the subduction is complex in this region seismic swarms often occur moderate mw 6 to large mw 7 earthquakes occur repeatedly and finally megathrust earthquakes of magnitudes significantly larger than 8 occur once in a while the last one being in 1922 almost a century ago we use new gps data we collected in the atacama region between 2008 and 2012 to complete and densify existing data we acquired since 2004 in north central chile these new data allow to quantify the motion of the andean sliver and assess the kinematic coupling on the subduction interface at these latitudes we find that only 7 per cent of the whole convergence motion is taken up by an eastward rotation of the rigid sliver a large part of the remaining 93 per cent approximately 6 cm yr gives way to accumulation of elastic deformation in the upper plate due to locking on the plate interface this accumulation shows important along strike and along dip variations interpreted in terms of variable coupling which we correlate with seismicity we identify two areas of low coupling near the la serena 30 s and baranquilla 27 5 s bays both are correlated with the subduction of singular bathymetric features and seem to stop the propagation of large seismic ruptures these zones are also seismic swarm prone areas which seem to occur rather on their edges these low coupling areas separate two seismic segments where coupling is high the atacama segment 100 km long between 29 s and 28 s and the cha naral segment 200 km long between 27 s and 25 s should they rupture alone these segments are sufficiently coupled and apparently since long enough to produce mw 8 events however a collective failure of both segments could generate a megathrust earthquake of magnitude close to 8 5 similar to the 1819 and 1922 complex events which produced important tsunamis such giant events may occur in the area once a century

slab1 0 a three dimensional model of global subduction zone geometries 1 we describe and present a new model of global subduction zone geometries called slab1 0 an extension of previous efforts to constrain the two dimensional non planar geometry of subduction zones around the focus of large earthquakes slab1 0 describes the detailed non planar three dimensional geometry of approximately 85 of subduction zones worldwide while the model focuses on the detailed form of each slab from their trenches through the seismogenic zone where it combines data sets from active source and passive seismology it also continues to the limits of their seismic extent in the upper mid mantle providing a uniform approach to the definition of the entire seismically active slab geometry examples are shown for two well constrained global locations models for many other regions are available and can be freely downloaded in several formats from our new slab1 0 website http on doi gov d9arbs we describe improvements in our two dimensional geometry constraint inversion including the use of average active source seismic data profiles in the shallow trench regions where data are otherwise lacking derived from the interpolation between other active source seismic data along strike in the same subduction zone we include several analyses of the uncertainty and robustness of our three dimensional interpolation methods in addition we use the filtered subduction related earthquake data sets compiled to build slab1 0 in a reassessment of previous analyses of the deep limit of the thrust interface seismogenic zone for all subduction zones included in our global model thus far concluding that the width of these seismogenic zones is on average 30 larger than previous studies have suggested

long term fault slip rates distributed deformation rates and forecast of seismicity in the western united states from joint fitting of community geologic geodetic and stress direction data sets 1 the long term average velocity field of the western united states is computed with a kinematic finite element code community data sets include fault traces geologic offset rates geodetic velocities principal stress directions and euler poles there is an irreducible minimum amount of distributed permanent deformation which accommodates one third of pacific north america relative motion in california much of this may be due to slip on faults not included in the model all data sets are fit at a common rms level of 1 8 datum standard deviations experiments with alternate weights fault sets and euler poles define a suite of acceptable community models in pseudoprospective tests fault offset rates are compared to 126 additional published rates not used in the computation 44 are consistent another 48 have discrepancies under 1 mm a 1 and 8 have larger discrepancies updated models are then computed novel predictions include dextral slip at 2 3 mm a 1 in the brothers fault zone two alternative solutions for the mendocino triple junction slower slip on some trains of the san andreas fault than in recent hazard models and clockwise rotation of some domains in the eastern california shear zone long term seismicity is computed by assigning each fault and finite element the seismicity parameters coupled thickness corner magnitude and spectral slope of the most comparable type of plate boundary this long term seismicity forecast is retrospectively compared to instrumental seismicity the western united states has been 37 below its long term average seismicity during 1977 2008 primarily because of temporary reduced activity in the cascadia subduction zone and san andreas fault system

active tectonics within the nw and se extensions of the pambak sevan syunik fault implications for the present geodynamics of armenia this study analyzes the active tectonics within the northwestern and southeastern extensions of the pambak sevan syunik fault pssf a major right lateral strike slip fault cutting through armenia quantifying the deformations in terms of geometry kinematics slip rates and earthquake activity using cosmogenic 3he osl irsl and radiocarbon dating techniques reveal different behaviors between the two regions within the northwestern extension in the region of amasia the pssf bends to the west and splits into two main wnw ese trending reverse faults defining a compressional pop up structure we estimate an uplift rate and a shortening rate of 0 5 0 1 mm y and 1 4 0 6 mm y respectively this suggests that most of the 2 mm y right lateral movement of the pssf seems to be absorbed within the amasia pop structure within the southeastern extension the pssf shows signs of dying out within the tsghuk volcano region at the southernmost tip of the syunik graben there the tectonic activity is characterized by a very slow ns trending normal faulting associated with a slight right lateral movement slip rates analyses i e vertical slip rate ew stretching rate at 90 to the fault and right lateral slip rate of 0 2 mm y 0 1 mm y and 0 05 mm y respectively lead to the conclusion that the right lateral movement observed further north along the pssf is mainly transferred within other active faults further west within the karabagh hagari fault or other structures further northwestwards comparing our slip rates with those estimated from gps data suggests that most of the deformation is localized and seismic at least within the tsghuk region the geometrical and kinematic pattern observed within the two terminations of the pssf suggests that the fault and its surrounding crustal blocks are presently rotating anticlockwise as also observed within the gps velocity field this is consistent with the recent kinematic models proposed for the caucasus kura south caspian region and brings a new insight into the present geodynamics of armenia

exploratory models of long term crustal flow and resulting seismicity across the alpine aegean orogen 1 long term crustal flow is computed with a kinematic finite element model based on iterated weighted least squares fits to data and prior constraints data include 773 fault traces 106 fault offset rates 510 geodetic velocities 2566 principal stress azimuths and velocity boundary conditions representing the rigid parts of the eurasia africa and anatolia plates model predictions include long term velocities fault slip rates and distributed permanent strain rates between faults one model assumes that geodetic velocities measured adjacent to the aegean trench reflect a temporarily locked subduction zone in this case long term subduction velocity averages 45 mm yr and rapid crustal extension is predicted in the southern aegean sea another model assumes steady creeping subduction in this case subduction velocity averages only 29 mm yr and the eastern aegean seafloor is predicted to be more nearly rigid long term seismicity maps are computed for each model on the basis of the shift hypotheses and previous global calibrations of plate boundary earthquake production retrospective comparisons to seismic catalogs are encouraging map patterns spatial distribution functions and total earthquake counts are all comparable while neither model accurately predicts earthquake rates at all magnitudes the creeping subduction model is more accurate for strong m6 events which dominate the seismic hazard

distribution of discrete seismic asperities and aseismic slip along the ecuadorian megathrust abstract a dense gps network deployed in ecuador reveals a highly heterogeneous pattern of interseismic coupling confined in the first 35 km depth of the contact between the subducting oceanic nazca plate and the north andean sliver interseismic models indicate that the coupling is weak and very shallow 0 15 km in south ecuador and increases northward with maximum found in the rupture areas of large mw 7 0 megathrust earthquakes that occurred during the 20th century since the great 1906 mw 8 8 colombia ecuador earthquake may have involved the simultaneous rupture of three to six asperities only one or two asperities were reactivated during the large seismic sequence of 1942 mw 7 8 1958 mw 7 7 1979 mw 8 2 and 1998 mw 7 1 the axis of the carnegie ridge which is entering the subduction zone south of the equator coincides well with the location of a 50 km wide creeping corridor that may have acted as persistent barrier to large seismic ruptures south of this creeping region a highly locked asperity is found right below la plata island while this asperity may have the potential to generate an mw 7 0 7 5 earthquake and a local tsunami until now it is unknown to have produced any similar events that region is characterized by the presence of slow slip events that may contribute significantly to reduce the long term moment deficit accumulated there and postpone the failure of that asperity at the actual accumulation rate a characteristic recurrence time for events such as those in 1942 1958 and 1979 is 140 30 yr 90 20 yr 153 80 yr respectively for the great 1906 event we find a recurrence time of at least 575 100 yr making the great 1906 earthquake a rare super cycle event

deformation of western turkey from a combination of permanent and campaign gps data limits to block like behavior 1 we present a new geodetic velocity field covering western turkey south of the north anatolian fault our velocity field is derived from a combination of continuously recording gps stations operating since 2003 survey type gps measurements carried out in the period 1997 2005 and velocities from reilinger et al 2006 the velocity field indicates that western turkey currently undergoes extension whose rate increases from the anatolia plateau to the aegean coast the overall extension in westernmost turkey is about 20 mm yr making it one of the fastest areas of continental extension in the world we test whether the observed deformation is better represented by the rotation of crustal blocks or by more distributed deformation while no deformation is detected in the central anatolian plateau we observe a deformation field west of the plateau that cannot be explained by block models unless the blocks are so small as to be essentially indistinguishable from a continuum although concentration of strain rates up to 140 nstrain yr are found across the major grabens strain rates above 50 nstrain yr are found throughout western turkey the distributions of topography and crustal thickness in western turkey agree with the distributions expected if the crust there had a constant thickness at 5 ma equal to that of the present central anatolian plateau and had subsequently been thinned at the present day distribution of strain rates our results therefore suggest that extensional strain affects the whole continental lithosphere of western turkey rather than being restricted to a small number of block boundaries

impact of coating development on the hydraulic and transport properties in argillaceous limestone fracture 1 results are reported for an acidic water flow through experiment conducted in a fractured argillaceous limestone sample 73 carbonates the change in fracture geometry and related parameters is reported for six data sets obtained from synchrotron x ray microtomography experiments high resolution three dimensional images of the sample allowed quantification of the changes in fracture morphology at a spatial resolution of 6 m mineral mass loss and permeability changes in the sample were also determined several physico chemical phenomena were identified during the experiment initial smooth fracture surfaces evolved rapidly toward rough surfaces with uneven clay coverage due to the preferential dissolution of carbonate minerals compared to clay minerals whose dissolution rate is about 106 slower a microporous clay coating progressively developed at the fluid rock interface during heterogeneous dissolution of the fracture while the global dissolution rate of the fracture walls exponentially decreased the increase in surface roughness and the presumed reorganization of clays caused a progressive reduction in permeability during the last flow through stage a large decrease in sample permeability was attributed to the large removal of clay particles this process was responsible for a dramatic collapse of the fracture walls near the sample inlet and led to the development of preferential flow pathways the development of the clay coating also acted as a barrier to flow and mass transfer between calcite grains and bulk solution and affected transport processes within the fracture

the adriatic region an independent microplate within the africa eurasia collision zone 1 we use gps measurements and block modeling to investigate the present day deformation of the adriatic region whose kinematics within the nubia eurasia plate boundary zone is not well constrained and remains controversial block modeling allows us to compute rigid plate angular velocities while accounting for elastic strain accumulation along block bounding faults results suggest that the adriatic is a microplate adria and that the southern boundary with the nubia plate and the aegean domain may be located along the apulia escarpment and the kefallinia fault geodetic data alone cannot discriminate between a single block ap or a two blocks gdap description of adria but the gdap model predicts boundary slip rates that are in better agreement with observations from previous studies

continuous gps array and present day crustal deformation of japan a gps array with about 1 000 permanent stations is under operation in japan the gps array revealed coseismic deformations associated with large earthquakes and ongoing secular deformation in the japanese islands based on daily coordinate data of the gps stations strain rate distribution is estimated most regions with a large strain rate are related to plate boundaries and active volcanoes in addition the niigata kobe tectonic zone nktz is recognized as a region of large strain rate along the japan sea coast and in the northern chubu and kinki districts this newly found tectonic zone may be related to a hypothetical boundary between the eurasian or amurian and the okhotsk or north america plates precise observation of crustal deformation provides important boundary conditions on numerical modeling of earthquakes and other crustal activities appropriate computation methods of continuous deformation field are directly applicable to data assimilation for such numerical simulations

gps measurements of present day convergence across the nepal himalaya the high elevations of the himalaya and tibet result from the continuing collision between india and asia which started more than 60 million years ago1 4 from geological and seismic studies of the slip rate of faults in asia5 it is believed that approximately one third of the present day convergence rate between india and asia 58 4mmyr 1 is responsible for the shortening uplift and moderate seismicity of the himalaya great earthquakes also occur infrequently in this region releasing in minutes the elastic strain accumulated near the boundary zone over several centuries and accounting for most of the advance of the himalaya over the plains of india the recurrence time for these great earthquakes is determined by the rate of slip of india beneath tibet which has hitherto been estimated indirectly from global plate motions6 from the slip rates of faults in asia7 8 from seismic productivity9 and from the advance of sediments on the northern ganges plain10 here we report geodetic measurements using the global positioning system gps of the rate of contraction across the himalaya which we find to be 17 52 2 mm yr 1 from the form of the deformation field we estimate the rate of slip of india beneath tibet to be 20 5 2 mmyr 1 strain sufficient to drive one or more great himalayan earthquakes with slip similar to that accompanying the magnitude 8 1 bihar nepal 1934 earthquake may currently be available in western nepal

the tectonic framework of the sumatran subduction zone the great aceh andaman earthquake of december 26 2004 and its tragic consequences brought the sumatran region and its active tectonics into the world s focus the plate tectonic setting of sumatra has been as it is today for tens of millions of years and catastrophic geologic events have likely been plentiful the immaturity of our understanding of great earthquakes and other types of geologic hazards contributed to the surprise regarding the location of the 2004 earthquake the timing however is probably best understood simply in terms of the inevitability of the infrequent events that shape the course of geologic progress our best hope is to improve understanding of the processes involved and decrease our vulnerability to them

new gps constraints on active deformation along the africa iberia plate boundary abstract we use velocities from 65 continuous stations and 31 survey mode gps sites as well as kinematic modeling to investigate present day deformation along the africa iberia plate boundary zone in the western mediterranean region the gps velocity field shows southwestward motion of the central part of the rif mountains in northern morocco with respect to africa varying between 3 5 and 4 0 mm yr consistent with prior published results stations in the southwestern part of the betic mountains of southern spain move west southwest with respect to eurasia 2 3 mm yr the western component of betics motion is consistent with partial transfer of nubia eurasia plate motion into the southern betics the southward component of betics motion with respect to iberia is kinematically consistent with south to southwest motion of the rif mountains with respect to africa we use block modeling constrained by mapped surface faults and seismicity to estimate the geometry and rates of strain accumulation on plate boundary structures our preferred plate boundary geometry includes one block between iberia and africa including the sw betics alboran sea and central rif this geometry provides a good fit to the observed motions suggesting a wide transpressive boundary in the westernmost mediterranean with deformation mainly accommodated by the gloria azores fault system to the west and the rif tell lineament to the east block boundaries encompass aspects of earlier interpretations suggesting three main deformation styles i extension along the ne sw trending trans alboran shear zone ii dextral strike slip in the betics corresponding to a well defined e w seismic lineament and iii right lateral strike slip motion extending west to the azores and right lateral motion with compression extending east along the algerian tell we interpret differential motion in the rif alboran betic system to be driven both by surface processes related the africa eurasia oblique convergence and sub crustal dynamic processes associated with the long history of subduction of the neotethys ocean lithosphere the dextral slip identified in the betic mountains in southern spain may be related to the offshore fault that produced the great 1755 lisbon earthquake and as such may represent a significant seismic hazard for the west mediterranean region

nw iran eastern turkey present day kinematics results from the iranian permanent gps network abstract a network of continuous gps stations has been installed in nw iran since 2005 to complement the survey gps network already existing in the region we present the 1999 2009 gps derived velocity field for this region based on the continuous and survey mode observations the results confirm a right lateral slip of 7 1 mm yr for the north tabriz fault in agreement with previous studies this rate is consistent with earthquakes of magnitude 7 7 3 and recurrence times of 250 300 yr the higher spatial coverage of the new network shows that deformation is localized in the vicinity of the chalderan south gailatu siah cheshmeh khoy fault and the north tabriz fault however the eastern end of the north tabriz fault appears to cross mount bozgush rather than following its southern foothills this new velocity field does not indicate the 8 mm yr of nne ssw extension suggested earlier for the region but rather shows lower extension of 1 2 1 mm yr across the eastern segment of the north tabriz fault and the talesh to the west the chalderan and the western north tabriz fault segment act like pure strike slip faults without significant extension or compression the denser network in the rudbar earthquake region ms 7 3 1992 shows no significant motion across the fault suggesting that the recurrence time of earthquakes like the rudbar event must be very long the lack of substantial compressive strain and the sharp azimuth change of the velocity vectors in the transition zone from arabia to lesser caucasus motion imply that processes other than extrusion possibly related to old subduction or delamination contribute to active deformation

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

active deformation in eastern indonesia and the philippines from gps and seismicity data in this study we combine global positioning system gps velocities with information on the style of regional seismicity to obtain a self consistent model velocity and strain rate field for the entire eastern indonesia and philippines region in the process of interpolating 93 previously published gps velocities the style and direction of the seismic strain rate field inferred from earthquakes with m0 1 1020 n m from the harvard centroid moment tensor catalog are used as constraints on the style and direction of model strain rates within the plate boundary zones the style and direction of the seismic strain rate field are found to be self similar for earthquakes up to m0 1 1020 n m equivalent to mw 7 3 our inversion result shows the following the java trench which lacks any significant historic seismicity delineates the australian plate au sunda block sunda plate boundary west of the island of sumba east of sumba convergence is distributed over the back arc and banda sea and there is no subduction at the timor trough suggesting that the northern boundary of the au plate runs north of this part of the banda arc through the banda sea in new guinea most motion is taken up as strike slip deformation in the northern part of the island delineating the pacific plate pa au boundary however some trench normal convergence is occurring at the new guinea trench evidence that the strain is partitioned in order to accommodate oblique pa au motion pa au motion is consistent with nuvel 1a direction but 8 mm yr 1 slower than the nuvel 1a estimate for pa au motion the sulawesi trench and molucca sea delineate zones of high strain rates consistent with high levels of active seismicity the sulawesi trench may take up some of the au sunda motion philippine sea plate motion is in a direction slightly northward of the nuvel ia estimate and is partitioned in some strike slip strain rates along the philippine fault and relatively larger trench normal convergence along the philippine trench and on the philippine mainland in the southern philippines and along the manila trench in the northern philippine islands the high level of strain rate along the manila trench is not released by any significant historic seismic activity for the entire eastern indonesia philippines region seismicity since 1963 has taken up 40 of the total moment rate inferred from our model

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

balancing the plate motion budget in the south island new zealand using gps geological and seismological data summary the landmass of new zealand exists as a consequence of transpressional collision between the australian and pacific plates providing an excellent opportunity to quantify the kinematics of deformation at this type of tectonic boundary we interpret gps geological and seismological data describing the active deformation in the south island new zealand by using an elastic rotating block approach that automatically balances the pacific australia relative plate motion budget the data in new zealand are fit to within uncertainty when inverted simultaneously for angular velocities of rotating tectonic blocks and the degree of coupling on faults bounding the blocks we find that most of the plate motion budget has been accounted for in previous geological studies although we suggest that the porter s pass amberley fault zone in north canterbury and a zone of faults in the foothills of the southern alps may have slip rates about twice that of the geological estimates up to 5 mm yr 1 of active deformation on faults distributed within the southern alps 100 km to the east of the alpine fault is possible the role of tectonic block rotations in partitioning plate boundary deformation is less pronounced in the south island compared to the north island vertical axis rotation rates of tectonic blocks in the south island are similar to that of the pacific plate suggesting that edge forces dominate the block kinematics there the southward migrating chatham rise exerts a major influence on the evolution of the new zealand plate boundary we discuss a model for the development of the marlborough fault system and hikurangi subduction zone in the context of this migration

geodetic exploration of strain along the el pilar fault in northeastern venezuela we use global navigation satellite systems observations in northeastern venezuela to constrain the el pilar fault epf kinematics and to explore the effects of the variable elastic properties of the surrounding medium and of the fault geometry on inferred slip rates and locking depth the velocity field exhibits an asymmetric velocity gradient on either side of the epf we use five different approaches to explore possible models to explain this asymmetry first we infer a 1 6 km locking depth using a classic elastic half space dislocation model second we infer a 1 5 km locking depth and a 0 33 asymmetry coefficient using a heterogeneous asymmetric model including contrasting material properties on either side of a vertical fault suggesting that the igneous metamorphic terranes on the northern side are 2 times more rigid than the sedimentary southern side third we use a three dimensional elastostatic model to evaluate the presence of a compliant zone suggesting a 30 reduction of rigidity in the upper 3 km at the depth of a 1 to 5 km wide fault zone fourth we evaluate the distribution of fault slip revealing a widespread partial creep pattern in the eastern upper segment while the upper western segment exhibits a partially locked area which coincides with the rupture surface of the 1797 and 1929 earthquakes to supplement these models we upgrade the previously published displacement simulation method using nonvertical dislocations with data acquired between 2003 and 2013 the localized aseismic displacement pattern associated with creeping or partially creeping fault segments could explain the low level of historic seismicity

tsunami hazard posed to new zealand by the kermadec and southern new hebrides subduction margins an assessment based on plate boundary kinematics interseismic coupling and historical seismicity we assess the tsunami hazard posed to new zealand by the kermadec and southern new hebrides subduction margins neither of these subduction zones has produced tsunami large enough to cause significant damage in new zealand over the past 150 years of well recorded history however as this time frame is short compared to the recurrence interval for major tsunamigenic earthquakes on many of the earth s subduction zones it should not be assumed that what has been observed so far is representative of the long term for each of these two subduction zones we present plate kinematic and fault locking results from block modelling of earthquake slip vector data and gps velocities the results are used to estimate the current rates of strain accumulation on the plate interfaces where large tsunamigenic earthquakes typically occur we also review data on the larger historical earthquakes that have occurred on these margins as well as the global cmt catalogue of events since 1976 using this information we have developed a set of scenarios for large earthquakes which have been used as initial conditions for the comcot tsunami code to estimate the subsequent tsunami propagation in the southwest pacific and from these the potential impact on new zealand has been evaluated our results demonstrate that there is a significant threat posed to the northland and coromandel regions of new zealand should a large earthquake m w 8 5 occur on the southern or middle regions of the kermadec trench and that a similarly large earthquake on the southern new hebrides trench has the potential to strongly impact on the far northern parts of new zealand close to the southern end of the submarine three kings ridge we propose logic trees for the magnitude frequency parameters of large earthquakes originating on each trench which are intended to form the basis for future probabilistic studies

neotectonic architecture of taiwan and its implications for future large earthquakes the disastrous effects of the 1999 chi chi earthquake in taiwan demonstrated an urgent need for better knowledge of the island s potential earthquake sources toward this end we have prepared a neotectonic map of taiwan the map and related cross sections are based upon structural and geomorphic expression of active faults and folds both in the field and on shaded relief maps prepared from a 40 m resolution digital elevation model augmented by geodetic and seismologic data the active tandem suturing and tandem disengagement of a volcanic arc and a continental sliver to and from the eurasian continental margin have created two neotectonic belts in taiwan in the southern part of the orogen both belts are in the final stage of consuming oceanic crust collision and suturing occur in the middle part of both belts and postcollisional collapse and extension dominate the island s northern and northeastern flanks both belts consist of several distinct neotectonic domains seven domains kaoping chiayi taichung miaoli hsinchu ilan and taipei constitute the western belt and four domains lutao lanyu taitung hualien and ryukyu make up the eastern belt each domain is defined by a distinct suite of active structures for example the chelungpu fault source of the 1999 earthquake and its western neighbor the changhua fault are the principal components of the taichung domain whereas both its neighboring domains the chiayi and miaoli domains are dominated by major blind faults in most of the domains the size of the principal active fault is large enough to produce future earthquakes with magnitudes in the mid 7 values