radar interferometric mapping of deformation in the year after the landers earthquake although the 1992 landers california earthquake sequence occurred in an area well sampled by geodetic networks1 3 the postseismic deformation in the months following the earthquake has been measured at only 15 geodetic stations4 another shortcoming in the geodetic coverage occurs west of the primary rupture where the existing geodetic observations suggest but cannot resolve sympathetic slip on secondary faults1 such measurements which are needed to place the landers earthquake sequence in the context of a recurring seismic cycle in california can be obtained with the dense spatial coverage provided by satellite radar interferometry5 9 here we present radar maps of the surface deformation field which reveal features that would otherwise have been poorly sampled particularly if the earthquake had occurred in a less accessible area we see triggered slip at the level of several centimetres as far as 100 km from the primary rupture and can resolve the geodetic signal of at least one small magnitude 5 aftershock the amount of surface slip following the main shock is less than a decimetre and is consistent with an exponential decay time of several months for the postseismic deformation

early and persistent supershear rupture of the 2018 magnitude 7 5 palu earthquake the speed at which an earthquake rupture propagates affects its energy balance and ground shaking impact dynamic models of supershear earthquakes which are faster than the speed of shear waves often start at subshear speed and later run faster than eshelby s speed here we present robust evidence of an early and persistent supershear rupture at the sub eshelby speed of the 2018 magnitude 7 5 palu indonesia earthquake slowness enhanced back projection of teleseismic data provides a sharp image of the rupture process along a path consistent with the surface rupture trace inferred by subpixel correlation of synthetic aperture radar and satellite optical images the rupture propagated at a sustained velocity of 4 1 km s 1 from its initiation to its end despite large fault bends the persistent supershear speed is further validated by seismological evidence of far field rayleigh mach waves the unusual features of this earthquake probe the connections between the rupture dynamics and fault structure an early supershear transition could be promoted by fault roughness near the hypocentre steady rupture propagation at a speed unexpected in homogeneous media could result from the presence of a low velocity damaged fault zone

shallow slip deficit due to large strike slip earthquakes in dynamic rupture simulations with elasto plastic off fault response summary slip inversions of geodetic data from several large magnitude 7 strike slip earthquakes point to coseismic slip deficit at shallow depths 3 4 km that is coseismic slip appears to decrease towards the earth surface while the inferred slip distribution may be consistent with laboratory derived rate and state friction laws suggesting that the uppermost brittle crust may be velocity strengthening there remains a question of how the coseismic slip deficit is accommodated throughout the earthquake cycle the consequence of velocity strengthening fault friction at shallow depths is that the deficit of coseismic slip is relieved by post seismic afterslip and interseismic creep however many seismic events with inferred shallow slip deficit were not associated with either resolvable shallow interseismic creep or robust shallow afterslip hence the origin of shallow slip deficit remains uncertain in this study we investigate whether inelastic failure in the shallow crust due to dynamic earthquake rupture can explain the inferred deficit of shallow slip evidence for such failure is emerging from geologic seismic and geodetic observations we find that the amount of shallow slip deficit is proportional to the amount of inelastic deformation near the earth surface such deformation occurs under a wide range of parameters that characterize rock strength in the upper crust however the largest magnitude of slip deficit in models accounting for off fault yielding is 2 4 times smaller than that inferred from kinematic inversions of geodetic data to explain this discrepancy we further explore to what extent assumptions in the kinematic inversions may bias the inferred slip distributions inelastic deformation in the shallow crust reduces coseismic strain near the fault introducing an additional artificial deficit of up to 10 per cent of the maximum slip in inversions of geodetic data that are based on purely elastic models the largest magnitude of slip deficit in our models combined with the bias in inversions accounts for up to 25 per cent of shallow slip deficit which is comparable but still smaller than 30 60 per cent deficit inferred from kinematic inversions we discuss potential mechanisms that may account for the remaining discrepancy between slip deficit predicted by elasto plastic rupture models and that inferred from inversions of space geodetic data

coseismic displacements from the hector mine california earthquake results from survey mode global positioning system measurements we describe the collection and processing of global positioning system gps data from 77 locations around the hector mine earthquake which we use to estimate coseismic displacements related to this shock the existence of pre event gps data some collected to monitor postseismic displacements from the 1992 landers earthquake and some to establish survey control in the meizoseismal area provided a relatively dense coverage close to the rupture zone the data available were collected mostly within the 2 years prior to the 1999 earthquake we reobserved many points within a few days after the shock and all within 6 months after we include corrections for interseismic motion to provide the best value possible for coseismic motion caused by this earthquake the displacements in general display the pattern expected for a strike slip fault though a few show significant vertical motion the maximum horizontal displacement observed was 2 m one station between fault ruptures showed little horizontal motion but significant uplift

accounting for uncertain fault geometry in earthquake source inversions i theory and simplified application the ill posed nature of earthquake source estimation derives from several factors including the quality and quantity of available observations and the fidelity of our forward theory observational errors are usually accounted for in the inversion process epistemic errors which stem from our simplified description of the forward problem are rarely dealt with despite their potential to bias the estimate of a source model in this study we explore the impact of uncertainties related to the choice of a fault geometry in source inversion problems the geometry of a fault structure is generally reduced to a set of parameters such as position strike and dip for one or a few planar fault segments while some of these parameters can be solved for more often they are fixed to an uncertain value we propose a practical framework to address this limitation by following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models we develop a sensitivity analysis to small perturbations of fault dip and position the uncertainties of our fixed fault geometry are included in the inverse problem under the formulation of the misfit covariance matrix that combines both prediction and observation uncertainties we validate this approach with the simplified case of a fault that extends infinitely along strike using both bayesian and optimization formulations of a static slip inversion if epistemic errors are ignored predictions are overconfident in the data and slip parameters are not reliably estimated in contrast inclusion of uncertainties in fault geometry allows us to infer a robust posterior slip model epistemic uncertainties can be many orders of magnitude larger than observational errors for great earthquakes mw 8 not accounting for uncertainties in fault geometry may partly explain observed shallow slip deficits for continental earthquakes similarly ignoring the impact of epistemic errors can also bias estimates of near surface slip and predictions of tsunamis induced by megathrust earthquakes

thermal history of australian passive margin cover sequences accreted to timor during late neogene arc continent collision indonesia abstract paleotemperature indicators and apatite fission track analysis of australian continental margin cover sequences accreted to the active banda arc continent collision indicate little to no heating during rapid late neogene uplift and exhumation thermal maturation patterns of vitrinite reflectance conodont alteration and illite crystallinity show that peak paleotemperatures ppt increase with stratigraphic and structural burial the highest ppt is found in the northern hinterland of the accretionary wedge which was beneath progressively thicker parts of the upper plate towards the north major discontinuities in the pattern of ppt are associated with the position of major thrust ramps such as those forming the ramelau kekneno arch rka ppt for upper triassic to neogene strata south of the rka are 60 80 c which are similar to and in many cases lower than correlative and age equivalent units drilled on the nw australian shelf permian to lower triassic sedimentary strata thrust over younger units within and north of the rka have ppt of 100 220 c thrust sheets accreted beneath the upper plate have ppt approximately 90 c higher than those frontally accreted metamorphism of the northernmost units of these sequences yield ppt of 300 c thrust stacking yields an inverted thermal profile of ppt decreasing discontinuously downward and to the south towards the foreland the timing of ppt is constrained by apatite fission track ages from mostly triassic continental margin cover sequences ages of upper triassic units are primarily coeval with deposition and show little evidence of thermal annealing whereas those of lower triassic units are almost completely annealed and range from 1 8 0 5 19 2 9 7 ma the clustering of apatite fission track ages into two distinct groups indicates that the upper boundary of the partial annealing zone has remained for some time at a triassic stratigraphic interval in the slope and rise of the nw australian continental margin the position of this zone on the present shelf is higher in the stratigraphic column due to the greater thickness of post breakup shelf facies units thrust stacking of rise slope and shelf units produces an inverted vertical profile of increasing apatite fission track age with depth lack of any long confined track lengths in apatite from all of the units requires rapid and recent exhumation of the thrust stack which is coincident with rapid phases of pliocene pleistocene exhumation documented throughout timor these data preclude pre late miocene tectonic burial or pre pliocene exhumation of the nw australian continental margin

joint inversion for vp vs and vp vs at safod parkfield california we refined the three dimensional 3 d vp vs and vp vs models around the san andreas fault observatory at depth safod site using a new double difference dd seismic tomography code tomoddps that simultaneously solves for earthquake locations and all three velocity models using both absolute and differential p s and s p times this new method is able to provide a more robust vp vs model than that from the original dd tomography code tomodd obtained simply by dividing vp by vs for the new inversion waveform cross correlation times for earthquakes from 2001 to 2002 were also used in addition to arrival times from earthquakes and explosions in the region the vp values extracted from the model along the safod trajectory match well with the borehole log data providing in situ confirmation of our results similar to previous tomographic studies the 3 d structure around parkfield is dominated by the velocity contrast across the san andreas fault saf in both the vp and vs models there is a clear low velocity zone as deep as 7 km along the saf trace compatible with the findings from fault zone guided waves there is a high vp vs anomaly zone on the southwest side of the saf trace that is about 1 2 km wide and extends as deep as 4 km which is interpreted to be due to fluids and fractures in the package of sedimentary rocks abutting the salinian basement rock to the southwest the relocated earthquakes align beneath the northeast edge of this high vp vs zone we carried out a 2 d correlation analysis for an existing resistivity model and the corresponding profiles through our model yielding a classification that distinguishes several major lithologies

surface deformation associated with fractures near the 2019 ridgecrest earthquake sequence contemporary earthquake hazard models hinge on an understanding of how strain is distributed in the crust and the ability to precisely detect millimeter scale deformation over broad regions of active faulting satellite radar observations revealed hundreds of previously unmapped linear strain concentrations or fractures surrounding the 2019 ridgecrest earthquake sequence we documented and analyzed displacements and widths of 169 of these fractures although most fractures are displaced in the direction of the prevailing tectonic stress prograde a large number of them are displaced in the opposite retrograde direction we developed a model to explain the existence and behavior of these displacements a major implication is that much of the prograde tectonic strain is accommodated by frictional slip on many preexisting faults

coseismic and postseismic deformation due to the 2007 m5 5 ghazaband fault earthquake balochistan pakistan time series analysis of interferometric synthetic aperture radar data reveals coseismic and postseismic surface displacements associated with the 2007 m5 5 earthquake along the southern ghazaband fault a major but little studied fault in pakistan modeling indicates that the coseismic surface deformation was caused by 9 cm of strike slip displacement along a shallow subvertical fault the earthquake was followed by at least 1 year of afterslip releasing 70 of the moment of the main event equivalent to a m5 4 earthquake this high aseismic relative to the seismic moment release is consistent with previous observations for moderate earthquakes m 6 and suggests that smaller earthquakes are associated with a higher aseismic relative to seismic moment release than larger earthquakes

probing the mechanical properties of seismically active crust with space geodesy study of the coseismic deformation due to the 1992 mw7 3 landers southern california earthquake 1 the coseismic deformation due to the 1992 m w 7 3 landers earthquake southern california is investigated using synthetic aperture radar sar and global positioning system gps measurements the ers 1 satellite data from the ascending and descending orbits are used to generate contiguous maps of three orthogonal components east north up of the coseismic surface displacement field the coseismic displacement field exhibits symmetries with respect to the rupture plane that are suggestive of a linear relationship between stress and strain in the crust interferometric synthetic aperture radar insar data show small scale deformation on nearby faults of the eastern california shear zone some of these faults in particular the calico rodman and pinto mountain faults were also subsequently strained by the 1999 m w 7 1 hector mine earthquake i test the hypothesis that the anomalous fault strain represents essentially an elastic response of kilometer scale compliant fault zones to stressing by nearby earthquakes fialko et al 2002 the coseismic stress perturbations due to the landers earthquake are computed using a slip model derived from inversions of the insar and gps data calculations are performed for both homogeneous and transversely isotropic half space models the compliant zone model that best explains the deformation on the calico and pinto mountain faults due to the hector mine earthquake successfully predicts the coseismic displacements on these faults induced by the landers earthquake deformation on the calico and pinto mountain faults implies about a factor of 2 reduction in the effective shear modulus within the similar to 2 km wide fault zones the depth extent of the low rigidity zones is poorly constrained but is likely in excess of a few kilometers the same type of structure is able to explain high gradients in the radar line of sight displacements observed on other faults adjacent to the landers rupture in particular the lenwood fault north of the soggy lake has likely experienced a few centimeters of left lateral motion across 1 km wide compliant fault zone having the rigidity reduction of more than a factor of 2 the inferred compliant fault zones are interpreted to be a result of extensive damage due to past earthquakes

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

fault geometry inversion and slip distribution of the 2010 mw 7 2 el mayor cucapah earthquake from geodetic data author s huang mh fielding ej dickinson h sun j gonzalez ortega ja freed am burgmann r abstract 2016 american geophysical union all rights reserved the 4 april 2010 mw 7 2 el mayor cucapah emc earthquake in baja california and sonora mexico had primarily right lateral strike slip motion and a minor normal slip component the surface rupture extended about 120 km in a nw se direction west of the cerro prieto fault here we use geodetic measurements including near to far field gps interferometric synthetic aperture radar insar and subpixel offset measurements of radar and optical images to characterize the fault slip during the emc event we use dislocation inversion methods and determine an optimal nine segment fault geometry as well as a subfault slip distribution from the geodetic measurements with systematic perturbation of the fault dip angles randomly removing one geodetic data constraint or different data combinations we are able to explore the robustness of the inferred slip distribution along fault strike and depth the model fitting residuals imply contributions of early postseismic deformation to the insar measurements as well as lateral heterogeneity in the crustal elastic structure between the peninsular ranges and the salton trough we also find that with incorporation of near field geodetic data and finer fault patch size the shallow slip deficit is reduced in the emc event by reductions in the level of smoothing these results show that the outcomes of coseismic inversions can vary greatly depending on model parameterization and methodology

scaling of fault parameters for continental strike slip earthquakes the long standing conflict between the predictions of elastic dislocation models and the observation that average coseismic slip increases with rupture length is resolved with application of a simple displacement depth function and the assumption that the base of the seismogenic zone does not result from the onset of viscous re laxation but rather a transition to stable sliding in a medium that remains stressed at or close to failure the resulting model maintains the idea of self similarity for earth quakes across the entire spectrum of earthquake sizes

complex deformation at shallow depth during the 30 october 2016 m w 6 5 norcia earthquake interference between tectonic and gravity processes the relation between slip at the near surface and at depth during earthquakes is still not fully resolved at the moment this deficiency leads to large uncertainties in the evaluation of the magnitude of past earthquakes based on surface observations which is the only accessible evidence for such events a better knowledge of the way slip distributes over distinct rupture strands within the first few kilometers from the surface would contribute greatly to reduce these uncertainties the 30 october 2016 mw6 5 norcia earthquake has been captured by a variety of geodetic techniques which provide access to the slip distribution both at depth and at the ground surface with an unprecedented level of detail for a normal faulting earthquake we first present coseismic surface offset measurements from correlation of optical satellite images of submetric resolution which are compared to field observations made shortly after the earthquake based on a joint inversion of optical data together with insar and gps data we then propose a rupture model that explains the observations both at far field and near field scales finally we explore different rupture geometries at shallow depth in an attempt to better explain the near field deformation i e within the first hundreds of meters around the fault observed at the surface despite the fact that the solution is not unique several lines of evidence suggest that gravity processes could be locally involved which interfere with the dominant tectonic processes

collisional melange development geologic associations of active melange forming processes with exhumed melange facies in the western banda orogen indonesia analysis of block assemblages matrix clay mineral composition and microfauna and offshore seismic reflection profiles reveal that the bobonaro melange in the timor region is sourced from mud rich australian continental margin sequences that are remobilized during accretion and form various facies depending on the structural conditions of emplacement melange facies include broken formation matrix rich mud injections and classic mixed block in clay facies each of these are distinguished by varying degrees of remobilization mixing and dispersion at different structural positions across the orogenic wedge the most important structural control is whether melange was generated beneath or in front of upper plate banda forearc basement banda terrane at the present collisional deformation front in the timor trough seismic reflection profiles show that melange forms mostly by stratal detachment and fluid assisted remobilization above a basal decollement propagating laterally along overpressured jurassic to cretaceous clay rich sequences of the distal australian continental margin the broken clay rich material injects upward through faults to form intrusive bodies at the base of slope cover sediment to form mud ridges at the surface similar patterns of stratal disruption are exposed onshore in the pliocene kolbano fold and thrust wedge of southern timor which is structurally contiguous with the timor trough deformation front melange in the kolbano mountains is mostly broken formation and matrix rich injections of mud from jurassic and cretaceous units deformation mechanisms include intense layer parallel extension associated with emplacement by mud diapirs that rise from near the decollement upward to the surface along fault conduits in the hinterland of the orogenic wedge east timor and northern west timor melange is dominantly of mixed block in clay facies with large blocks derived from roof thrust sheets of intermixed banda terrane and maubisse formation units at the structural base of these thrust sheets is the sonnebait disruption zone sdz which formed the initial suture between the banda terrane and structurally underthrust australian continental margin sequences during the late miocene to early pliocene the thickest accumulations of mixed block in clay melange in the timor region are found at the southern edge outlet of the sdz near the central and viqueque synorogenic basins the extent of block dispersion and mixing in the sdz is indicative of intense shear strains perhaps induced by an oversupply of accretable material when the suture zone was clogged by underthrusting of the australian continental margin

complex rupture of an immature fault zone a simultaneous kinematic model of the 2019 ridgecrest ca earthquakes the july 4 2019 mw6 4 and subsequent july 6 2019 mw7 1 ridgecrest sequence earthquakes ruptured orthogonal fault planes in the little lake fault zone a low slip rate 1 mm yr dextral fault zone in the area linking the eastern california shear zone and walker lane this region accommodates nearly one fourth of plate boundary motion and has been proposed to be an incipient transform fault system that could eventually become the main tectonic boundary replacing the san andreas we investigate the rupture process of these events using a novel simultaneous kinematic slip method with joint inversion of high rate gnss strong motion gnss static offset and insar data we model the coulomb stress change to evaluate how the first mainshock may have affected the second our findings suggest complex interactions between several fault structures including dynamic and static triggering and provide important context for regional seismic source characterization and hazard models

phase gradient approach to stacking interferograms the phase gradient approach is used to construct averages and differences of interferograms without phase unwrapping our objectives for change detection are to increase fringe clarity and decrease errors due to tropospheric and ionospheric delay by averaging many interferograms the standard approach requires phase unwrapping scaling the phase according to the ratio of the perpendicular baseline and finally forming the average or difference however unique phase unwrapping is usually not possible since the phase gradient due to topography is proportional to the perpendicular baseline phase unwrapping is unnecessary prior to averaging or differencing phase unwrapping may be needed to interpret the results but it is delayed until all of the largest topographic signals are removed we demonstrate the method by averaging and differencing six interferograms having a suite of perpendicular baselines ranging from 18 to 406 m cross spectral analysis of the difference between two tandem interferograms provides estimates of spatial resolution which are used to design prestack filters a wide range of perpendicular baselines provides the best topographic recovery in terms of accuracy and coverage outside of mountainous areas the topography has a relative accuracy of better than 2 m residual interferograms single interferogram minus stack have tilts across the unwrapped phase that are typically 50 mm in both range and azimuth reflecting both orbit error and atmospheric delay smaller scale waves with amplitudes of 15 mm are interpreted as atmospheric lee waves a few global positioning system gps control points within a frame could increase the precision to 20 mm for a single interferogram further improvements may be achieved by stacking residual interferograms

insar imaging of displacement on flexural slip faults triggered by the 2013 mw 6 6 lake grassmere earthquake central new zealand interferometric synthetic aperture radar insar data reveal surface slip on multiple faults triggered by the 2013 mw 6 6 lake grassmere earthquake new zealand surface offsets of 1 2 cm occurred on previously inferred flexural slip faults located 4 km from the epicenter we document dip slip on at least three different northeast striking northwest dipping flexural slip faults located in the western limb of a syncline the along strike extent of the triggered slip is 1 1 5 km for each fault dislocation models suggest that triggered slip is confined to shallow depths 800 m coulomb stress analysis indicates that slip was not triggered by the static stress change of the main shock but was likely caused by dynamic shaking during the passage of seismic waves our finding also provides an important clue on how some slip on shallow flexural slip faults takes place

transpressional rupture cascade of the 2016 mw 7 8 kaikoura earthquake new zealand large earthquakes often do not occur on a simple planar fault but involve rupture of multiple geometrically complex faults the 2016 m w 7 8 kaikoura earthquake new zealand involved the rupture of at least 21 faults propagating from southwest to northeast for about 180 km here we combine space geodesy and seismology techniques to study subsurface fault geometry slip distribution and the kinematics of the rupture our finite fault slip model indicates that the fault motion changes from predominantly right lateral slip near the epicenter to transpressional slip in the northeast with a maximum coseismic surface displacement of about 10 m near the intersection between the kekerengu and papatea faults teleseismic back projection imaging shows that rupture speed was overall slow 1 4 km s but faster on individual fault segments approximately 2 km s and that the conjugate oblique reverse north striking faults released the largest high frequency energy we show that the linking conway charwell faults aided in propagation of rupture across the step over from the humps fault zone to the hope fault fault slip cascaded along the jordan thrust kekerengu and needles faults causing stress perturbations that activated two major conjugate faults the hundalee and papatea faults our results shed important light on the study of earthquakes and seismic hazard evaluation in geometrically complex fault systems

primary surface rupture associated with the mw 7 1 16 october 1999 hector mine earthquake san bernardino county california the m w 7 1 hector mine earthquake occurred within the mojave desert portion of the eastern california shear zone and was accompanied by 48 km of dextral surface rupture complex northward rupture began on two branches of the lavic lake fault in the northern bullion mountains and also propagated southward onto the bullion fault lesser amounts of rupture occurred across two right steps to the south surface rupture was mapped using postearthquake 1 10 000 scale aerial photography field mapping provided additional detail and more than 400 fault rupture observations of these approximately 300 measurements were used to characterize the slip distribution en echelon surface rupture predominated in areas of thick alluvium whereas in the bedrock areas rupture was more continuous and focused within a narrower zone measured dextral offsets were relatively symmetrical about the epicentral region with a maximum displacement of 5 25 0 85 m 1 vertical slip was a secondary component and was variable with minor west side down displacements predominating in the bullion mountains field and aerial photographic evidence indicates that most of the faults that ruptured in 1999 had had prior late quaternary displacement although only limited sections of the rupture show evidence for prior holocene displacement 1 fn 1

evidence of fault immaturity from shallow slip deficit and lack of postseismic deformation of the 2017 mw 6 5 jiuzhaigou earthquake

some thoughts on measuring earthquake deformation using optical imagery optical imagery has been proven to be an effective tool for measuring earthquake deformation in continental regions since its first application in the 1999 izmit earthquake in this article we compile and analyze all the earthquakes that have been investigated with optical image matching by 2019 based on which we comment on various issues regarding measuring earthquake deformation with optical imagery new generations of very high resolution vhr data are effective for earthquake studies but orthorectification of the vhr images is the major source of error which is often ignored we found that the displacements derived from the worldview images strongly correlate with the errors in the shuttle radar topography mission srtm digital elevation model dem that was used in orthorectification based on the observed correlation between displacements and topography we propose a new dem based method using the advanced land observing satellite alos world 3 d dem to reduce the orthorectification errors combining the published optical data of earthquake deformation we re analyze the coseismic slip distribution and shallow slip deficit ssd the ssd model states that the coseismic slip in many strike slip earthquakes decreases in magnitude toward the surface but this model remains arguable because the interferometric synthetic aperture radar insar derived slip is usually not well constrained at shallow depths due to decorrelation because optical matching directly measures the surface slip we re examine the slip distribution of 11 strike slip earthquakes and find that the ssd model may primarily be artifacts in the insar measurements it is therefore of great importance to include the optical data in earthquake studies to constrain coseismic slip inversions

tectonic elements with south china affinity in the korean peninsula new early jurassic palaeomagnetic data summary early jurassic sandstones and shales were collected at 14 sites from the kimpo area in the western part of the korean peninsula for a palaeomagnetic study a characteristic remanent magnetization component which passes the fold test was isolated from seven sites this characteristic component is interpreted to be of primary early jurassic origin because the folding age is middle late jurassic the primary directions together with previously reported ones provide a mean direction d 38 1 i 39 7 95 3 8 11 sites and a palaeomagnetic pole 54 1 n 230 2 e a95 4 1 for the kimpo area this palaeomagnetic pole shows good agreement with the coeval poles for the south china block and is significantly removed from that for the north china block suggesting that the kimpo area has been part of the south china block since at least early jurassic times the kimpo area constitutes a part of the imjingang belt which is palaeontologically allocated to the south china block in its origin while all precambrian tectonic blocks that compose the basement of the korean peninsula are interpreted to be of north china origin we conclude that the imjingang belt including the kimpo area is a tectonic extension of the south china block on the korean peninsula the south china elements were obducted onto the north china block at the site of the present korean peninsula during the collision event of the north and south china blocks and hence the korean peninsula is composed of areas with both north and south china affinities

paleomagnetism of younger volcanics from western timor indonesia abstract paleomagnetic research has been carried out on volcanic rocks from two formations exposed in western timor indonesia i e the metan formation of eocene age and the manamas formation of late miocene age because of the chaotic tectonic setting of the rocks at the metan formation it was the inclination data from five lavas only that could be interpreted in the final analysis of the characteristic remanence directions chrm with i 33 6 a 95 4 1 the metan volcanics most probably extruded originally in the northern hemisphere at a latitude of about 17 the volcanics may have extruded on a crustal unit which includes a continental fragment that became detached from gondwana in mesozoic times and subsequently shifted to the southeast asian continent this crustal unit broke away from southeast asia in eocene times moved towards the south and collided 3 ma ago with the frontal part of the australian continental margin the manamas formation of late miocene age includes obducted volcanics consisting of both deep sea pillow lavas and island arc volcanics with chrm directions of d 132 6 i 15 8 no a 95 because 2 sites only and d 295 9 i 26 3 a 95 2 8 respectively the declinations of the chrm directions derived from the rocks from two localities show counterclockwise deviations of approximately 45 and 60 respectively relative to the present earth s field direction the deviating directions can be explained in terms of a counterclockwise rotation of timor which may have begun as early as 3 ma ago and which could be a result of the obliquely northward protruding australian continent where the originally west east directed banda arc rotated in a counterclockwise sense it is also possible that during the obduction the lava piles performed counterclockwise rotations rock magnetic analyses show that magnetite or and titanomagnetite is the main carrier of remanence

crustal earthquake instability in relation to the depth variation of frictional slip properties recent stability studies using constitutive relations of the type found by dieterich ruina and others to describe frictional slip of rocks in the laboratory have provided a new explanation of the depth cutoff of shallow crustal earthquakes the class of friction laws discussed has the property that the sliding stress depends on normal stress temperature slip rate and slip history for sliding at a fixed slip rate v and fixed environment e g normal stress temperature etc the shear strength evolves toward a steady state value ss v stability analysis show that for d ss v dv 0 velocity strengthening implies stable steady state sliding at least for a broad class of constitutive laws more fully described in the paper experiments by dieterich and by tullis and weeks on westerly granite with mature sliding surfaces indicate that d ss v dv is negative at room temperature whereas higher temperature experiments by stesky show that d ss v dv becomes positive above approximately 300 c therefore in the case of the earth where temperature increases with depth the above observations seem to suggest that the depth cutoff of crustal earthquake activity can be understood in terms of the variation of the frictional response with depth from a regime with d ss v dv 0 this is not inconsistent with but rather refines the suggestion by sibson and others that the depth cutoff is due to a transition from brittle friction to ductile flow further our results show definitively that the shallow depth confinement of seismicity is compatible with a model in which deformation is localized to a fault zone extending well below the seismogenic depth the depth confinement does not require a model showing transition to a zone of broadly distributed creep flow beneath the seismogenic zone following mavko a two dimensional quasi static strike slip fault model is analyzed but using different numerical procedures and a depth variation of frictional properties based on the laboratory data mentioned above and the lachenbruch sass depth variation of temperature for the san andreas fault the resulting predictions of such features as the confinement of crustal earthquakes to shallow depths the development of locked patches the recurrence time for the seismic cycle the seismic stress drop and displacement etc are generally in agreement with the observed characteristics of large scale strike slip earthquakes along the san andreas fault calculations based on the laboratory data predict for example that stick slip nucleates around 5 7 km that large seismic motion occurs around the nucleation depth and above but diminishes gradually to zero at 13 15 km depths that rapid postseismic creep occurs over another 3 4 km depth and that at greater depths steady slip consistent with the average plate velocity is only modestly perturbed by the earthquakes occurring above the most uncertain parameter is the slip weakening distance l for evolution of fault surface state we illustrate how features of the predicted earthquake cycles vary with l over the range for which calculations are feasible

rise and fall of the eastern great indonesian arc recorded by the assembly dispersion and accretion of the banda terrane timor abstract new age petrochemical and structural data indicate that the banda terrane is a remnant of a jurassic to eocene arc trench system that formed the eastern part of the great indonesian arc the arc system rifted apart during eocene to miocene supra subduction zone sea floor spreading which dispersed ridges of banda terrane embedded in young oceanic crust as far south as sumba and timor in timor the banda terrane is well exposed as high level thrust sheets that were detached from the edge of the banda sea upper plate and uplifted by collision with the passive margin of nw australia the thrust sheets contain a distinctive assemblage of medium grade metamorphic rocks overlain by cretaceous to miocene forearc basin deposits new u pb age data presented here indicate igneous zircons are less than 162 ma with a cluster of ages at 83 ma and 35 ma 40ar 39ar plateau ages of various mineral phases from metamorphic units all cluster at between 32 38 ma these data yield a cooling curve that shows exhumation from around 550 c to the surface between 36 28 ma after this time there is no evidence of metamorphism of the banda terrane including its accretion to the edge of the australian continental margin during the pliocene these data link the banda terrane to similar rocks and events documented throughout the eastern edge of the sunda shelf and the banda sea floor

ocean trench blocked and obliterated by banda forearc collision with australian proximal continental slope abstract the bathymetry and abrupt changes in earthquake seismicity around the eastern end of the java trench suggest it is now blocked south east of sumba by the australian jurassic rifted continental margin forming the largely submarine roti savu ridge plate reconstructions have demonstrated that from at least 45 ma the java trench continued far to the east of sumba from about 12 ma the eastern part of the java trench called banda trench continued as the active plate boundary located between what was to become timor island then part of the australian proximal continental slope and the banda volcanic arc this banda trench began to be obliterated by continental margin arc collision between about 3 5 and 2 ma the present position of the defunct banda trench can be located by use of plate reconstructions earthquake seismology deep reflection seismology dsdp 262 results and geological mapping as being buried under the para autochthon below the foothills of southern timor locating the former trench guides the location of the apparently missing large southern part of the banda forearc that was carried over the australian continental margin during the final stage of the period of subduction of that continental margin that lasted from about 12 ma to about 3 5 ma tectonic collision is defined and distinguished from subduction and rollback collision in the southern part of the banda arc was initiated when the overriding forearc basement of the upper plate reached the proximal part of the australian continental slope of the lower plate and subduction stopped collision is characterised by fold and thrust deformation associated with the development of structurally high decollements this collision deformed the basement and cover of the forearc accretionary prism of the upper plate with part of the unsubducted australian cover rock sequences from the lower plate together with parts of the forearc basement they now form the exposed banda orogen the conversion of the northern flank of the timor trough from being the distal part of the banda forearc accretionary prism carried over the australian continental margin into a foreland basin was initiated by the cessation of subduction and simultaneous onset of collisional tectonics this reinterpretation of the locked eastern end of the java trench proposes that from its termination south of sumba to at least as far east as timor and probably far beyond the java banda trench and forearc overrode the subducting australian proximal continental slope locally to within 60 km of the shelf break part of the proximal forearc s accretionary prism together with part of the proximal continental slope cover sequence were detached and thrust northwards over the java banda trench and forearc by up to 80 km along the southwards dipping savu thrust and wetar suture these reinterpretations explain the present absence of any discernible subduction ocean trench in the southern banda arc and the narrowness of the forearc reduced to 30 km at atauro north of east timor

the 2016 m7 kumamoto japan earthquake slip field derived from a joint inversion of differential lidar topography optical correlation and insar surface displacements

revisiting the 1992 landers earthquake a bayesian exploration of co seismic slip and off fault damage existing models for the distribution of subsurface fault slip associated with the 1992 landers ca earthquake m w 7 3 show significant dissimilarities in particular they exhibit different amounts of slip at shallow depths 5 km these discrepancies can be primarily attributed to the ill posed nature of the slip inversion problem and to the use of physically unjustifiable smoothing or regularization constraints in this study we propose a new coseismic model obtained from the joint inversion of multiple observations in a relatively unregularized and fully bayesian framework we use a comprehensive data set including gps terrestrial geodesy multiple sar interferograms and co seismic offsets from correlation of aerial images these observations provide dense coverage of both near and far field deformation to limit the impact of modelling uncertainties we develop a 3 d fault geometry designed from field observations co seismic offsets and the distribution of aftershocks in addition we account for uncertainty in the assumed elastic structure used to compute the green s functions our solution includes the ensemble of all plausible models that are consistent with our prior information and fit the available observations within data and prediction uncertainties using near fault high resolution ground deformation measurements and the density of aftershocks we investigate the properties of the damage zone and its impact on the inferred slip at depth we attribute a part of the inferred slip deficit at shallow depth to our models not including the impact of a damage zone associated with a reduction of shear modulus in the vicinity of the fault

melange versus forearc contributions to sedimentation and uplift during rapid denudation of a young banda forearc continent collisional belt abstract new sedimentary geochemistry and petrographic analyses provide the most extensive sedimentary documentation yet of the rapid denudation of the young timor orogen the data from three basins including two widely separated well dated sections of the synorogenic megasequence of timor leste and a re dated dsdp 262 constrain the source and timing of detrital sediment flux during forearc continent collision along the timor sector of the banda arc the exhumed synorogenic piggy back basins formed above a melange unit that developed at the expense of a weak stratigraphic horizon in the mesozoic stratigraphy and was exhumed to the sea floor in latest messinian time following an interval of deep marine chalky marl sedimentation an increasingly muddy sediment flux indicates that the island of timor became emergent and shed sediment by 4 5 ma comparison of exhumed sections with similar patterns in the dsdp262 chemistry suggests that the sediment source was probably located some 50 60 km distant from the basin which is consistent with the aileu region of timor leste that shows an appropriate exhumation history all sedimentation between 4 5 and 3 2 ma was probably derived from a low relief rapidly eroding and mudstone dominated landscape with geochemical affinities to the triassic mudstone derived synorogenic melange the melange unit overlies and surrounds the banda terrane and was presumably structurally emplaced by propagation of a decollement through the triassic rocks during the collision after 3 2 ma sedimentation was dominated by hard rock lithologies of the banda terrane consisting of forearc cover and basement the latter including elements of metamafic rocks and metapelites this phase of sedimentation was accompanied by rapid uplift which may have been partly driven by a transient imbalance between rock uplift and denudation as resistant lithologies emerged from below melange like mudstone previous work has suggested that the timing of collision in timor leste and west timor was substantially different our reevaluation of dsdp 262 facies migration history in the context of the re dating presented here favours a relatively synchronous onset of uplift in both halves of the island but with different partitioning of strain between the foreland and hinterland in each half of the island

refining the shallow slip deficit geodetic slip inversions for three major m w 7 strike slip earthquakes 1992 landers 1999 hector mine and 2010 el mayor cucapah show a 15 60 per cent reduction in slip near the surface depth 2 km relative to the slip at deeper depths 4 6 km this significant difference between surface coseismic slip and slip at depth has been termed the shallow slip deficit ssd the large magnitude of this deficit has been an enigma since it cannot be explained by shallow creep during the interseismic period or by triggered slip from nearby earthquakes one potential explanation for the ssd is that the previous geodetic inversions lack data coverage close to surface rupture such that the shallow portions of the slip models are poorly resolved and generally underestimated in this study we improve the static coseismic slip inversion for these three earthquakes especially at shallow depths by 1 including data capturing the near fault deformation from optical imagery and sar azimuth offsets 2 refining the interferometric synthetic aperture radar processing with non boxcar phase filtering model dependent range corrections more complete phase unwrapping by snaphu statistical non linear approach for phase unwrapping assuming a maximum discontinuity and an on fault correlation mask 3 using more detailed geologically constrained fault geometries and 4 incorporating additional campaign global positioning system gps data the refined slip models result in much smaller ssds of 3 19 per cent we suspect that the remaining minor ssd for these earthquakes likely reflects a combination of our elastic model s inability to fully account for near surface deformation which will render our estimates of shallow slip minima and potentially small amounts of interseismic fault creep or triggered slip which could make up a small percentages of the coseismic ssd during the interseismic period our results indicate that it is imperative that slip inversions include accurate measurements of near fault surface deformation to reliably constrain spatial patterns of slip during major strike slip earthquakes

coseismic surface deformation from air photos the kickapoo step over in the 1992 landers rupture coseismic deformation of the ground can be measured from aerial views taken before and after an earthquake we chose the area of the kickapoo landers step over along the 1992 landers earthquake zone using air photos scale 1 40 000 scanned at 0 4 m resolution two photos acquired after the earthquake are used to assess the accuracy and to evaluate various sources of noise optical distortions film deformation scanning errors or errors in viewing parameters can yield metric bias at wavelength larger than 1 km offset field at shorter wavelength is more reliable and mainly affected by temporal decorrelation of the images induced by changes in radiometry with time temporal decorrelation and resulting uncertainty on offsets are estimated locally from the correlation degree between the images relative surface displacements are measured independently every about 15 m and with uncertainty typically below 10 cm rms the offset field reveals most of the surface ruptures mapped in the field the fault slip is accurate to about 7 cm rms and measured independently every 200 m from stacked profiles slip distribution compares well with field measurements at the kilometric scale but reveals local discrepancies suggesting that deformation is generally although not systematically localized on the major fault zone located in the field this type of data can provide useful insight into the fault zone s mechanical properties our measurements indicate that elastic coseismic strain near the fault zone can be as large as 0 5 10 3 while anelastic yielding was attained for strain in excess of about 1 2 10 3

a silent mw 4 7 slip event of october 2006 on the superstition hills fault southern california 1 during october 2006 the 20 km long superstition hills fault shf in the salton trough southern california slipped aseismically producing a maximum offset of 27 mm as recorded by a creepmeter we investigate this creep event as well as the spatial and temporal variations in slip history since 1992 using ers 1 2 and envisat satellite data during a 15 year period steady creep is punctuated by at least three events the first two events were dynamically triggered by the 1992 landers and 1999 hector mine earthquakes in contrast there is no obvious triggering mechanism for the october 2006 event field measurements of fault offset after the 1999 and 2006 events are in good agreement with the interferometric synthetic aperture radar data indicating that creep occurred along the 20 km long fault above 4 km depth with most of the slip occurring at the surface the moment released during this event is equivalent to a mw 4 7 earthquake this event produced no detectable aftershocks and was not recorded by the continuous gps stations that were 9 km away modeling of the long term creep from 1992 to 2007 creep using stacked ers 1 2 interferograms also shows a maximum creep depth of 2 4 km with slip tapering with depth considering that the sediment thickness varies between 3 km and 5 km along the shf our results are consistent with previous studies suggesting that shallow creep is controlled by sediment depth perhaps due to high pore pressures in the unconsolidated sediments

the 2018 mw6 4 hualien earthquake dynamic slip partitioning reveals the spatial transition from mountain building to subduction abstract the hualien earthquake of 6 february 2018 occurred on the east coast of taiwan in the collision zone between the eurasia and philippine sea plates even though an event with a moderate magnitude of mw6 4 it caused widespread surface rupture in and around the city of hualien leading to significant loss of life and property damages in this study we investigate the rupture process of this earthquake using teleseismic strong motion gps and sar observations we first employ the geodetic data to search for the geometry of multiple fault planes followed by a multi point source inversion using teleseismic and strong motion waveforms to determine the possible change in mechanism during the rupture process we parameterize the fault model with three curved segments to represent the complicated fault system involved in the rupture process an offshore fault was ruptured by the hualien earthquake showing a curved geometry with the dip angle changing from shallow 45 in the north to sub vertical 80 in the south evidence from tomographic velocity model indicates that the offshore fault is the boundary between the subducted coastal range and meilun tableland which is also a plate interface finally a joint inversion is carried out to constrain the complete rupture process the inversion result reveals that the rupture initiated on the offshore fault interface and propagated unilaterally towards south southwest the rupture then jumped on to the sub vertical meilun fault and reached the ground surface significant dynamic slip partitioning occurred during the rupture process near the meilun fault with the majority of thrust and strike slip motions occurring on the off shore fault and the meilun fault respectively the afterslip model is inverted with sar timeseries spanning 6 months after the mainshock the afterslip model shows a strong complementary pattern with co seismic slips the comparison between the 1951 and 2018 hualien earthquake shows that the rupture behavior of the meilun fault does not follow a repeating earthquake pattern thrust motion may occur on the two side walls of the meilun tableland with a teeterboard uplift pattern in different earthquake cycles the change in geometry and slip on the inter plate fault appears to be related to the transition of the coastal range from mountain building to subduction

fault slip distribution of the 1999 mw 7 1 hector mine california earthquake estimated from satellite radar and gps measurements we use a combination of satellite radar and gps data to estimate the slip distribution of the 1999 m w 7 1 hector mine earthquake a right lateral strikeslip earthquake that occurred on a northwest southeast striking fault in the southern california mojave desert the data include synthetic aperture radar interferograms insar from both ascending and descending orbits radar amplitude image offset fields sario for both ascending and descending azimuth directions and campaign gps observations from 55 stations provided by agnew et al 2002 we model the fault with nine segments derived from the field mapped fault rupture the sario data and aftershock locations we first estimate the dip of each fault segment as well as a single constant strike slip component across each segment resulting in an average dip of 83 to the northeast and slip of up to 5 6 m then we fix the optimal fault segment dip discretize the fault segments into 1 5 km 1 5 km patches and solve for the variable slip distribution using a nonnegative least squares method that includes an appropriate degree of smoothing our preferred solution has both right lateral strike slip and reverse faulting the estimated geodetic moment is 5 93 10 19 n m m w 7 1 similar to seismological estimates indicating that there are insignificant interseismic and postseismic deformation signals in the data we find strike slip displacements of up to 6 0 m and reverse faulting of up to 1 6 m with the maximum slip located just northwest of the epicenter most of the slip is concentrated northwest and south of the epicenter little slip is found on the northeastern branch of the fault the sario data and our modeling indicate that the amount and extent of surface fault rupture were underestimated in the field

localized fault zone dilatancy and surface inelasticity of the 2019 ridgecrest earthquakes earthquakes produce a spectrum of elastic and inelastic deformation processes that are reflected across various length and time scales while elasticity has long dominated research assumptions in active tectonics increasing interest has focused on the inelastic characteristics of earthquakes particularly those of the surface fault rupture zone itself and how they relate to ground rupture hazard and the mechanics of damage zones here we present detailed co seismic surface strain analysis of the 2019 ridgecrest california earthquakes we derive three dimensional high resolution surface displacements from satellite optical imagery which we then invert for the co seismic surface strain tensors we show that fault zone dilation is pervasive throughout these earthquakes and that inelastic failure is present but relatively localized median width of 31 m the width of the inelastic failure zone is not correlated to off fault deformation surface geology or displacement magnitude instead the extent and kinematics of inelastic failure reflect active mylonitic deformation of the fault damage zone that is influenced by rupture velocity and fault maturity these results highlight how a single earthquake contributes to the long term permanent geologic record of faulting inelastic failure in the 2019 ridgecrest earthquakes was localized and influenced by mylonitic deformation of the fault damage zone according to an analysis of surface displacements derived from satellite images

numerical study of ground motion differences between buried rupturing and surface rupturing earthquakes recent ground motion observations suggest that surface rupturing earth quakes generate weaker near fault ground motion than buried earthquakes this dif ference is significant in the period range of 0 3 3 sec contributing factors to this phenomenon may include the effect of fault zone weakness at shallow depth on rup ture dynamics and rupture directivity during earthquakes we present results from numerical experiments of spontaneous dynamic rupture and near source ground motion simulations of surface rupturing and buried earth quakes and discuss mechanisms for the observed ground motion differences the surface rupturing earthquake is modeled with a shallow zone of 5 km thickness con taining areas of negative stress drop within the framework of the slip weakening fric tion model and lower rigidity surface rupturing models with this weak zone generate lower amplitude ground velocity than do models without this modification observed ground motion differences between surface and buried events are qual itatively reproduced by imposing higher stress drop in the buried earthquakes than in the surface earthquakes combined with introducing a deeper rupture initiation for buried rupture enhancing upward rupture directivity effects for the latter events in the context of our simplified model parameterization then the observed differences in ground motion could arise from combined effects of relative weakness of the shal low layer of faults the relatively larger stress drops of buried ruptures and a tendency of near fault sites to record strong upward directivity from buried ruptures

deformation and exhumation in timor distinct stages of a young orogeny abstract timor island in the outer banda arc bordering the timor sea preserves the orogenic product of an arc continent collision between the australian plate and the banda arc that commenced after 10 9 9 8 ma gts2004 but emerged above sea level only 3 1 ma ago the orogenic pile includes large tracts of material from the australian margin including the permian to middle jurassic gondwana megasequence and the late jurassic to early late miocene australian margin megasequence which occur in thrust slices in addition material from the banda arc side of the plate margin referred to as the banda terrane occurs throughout the island and includes both seafloor metamorphosed igneous material and cover sediments also in thrust sheets however the distribution of thrust slices is unclear in many areas perhaps because only the uppermost nappes of the thrust pile are currently emergent and also because the thrust piles have been disrupted by later high angle faulting evidence from east timor suggests that the major break between deformed pre collisional strata and the relatively undeformed overlying deposits was during the late miocene 9 8 5 5 ma we present evidence for the timing of three distinct phases of orogenic development as determined from east timor including initial collision and emplacement of the early nappes creating loading and diapirism within the 9 8 5 5 ma interval a tectonic quiet interval 5 5 ma 4 5 ma that extended for about a million years during the middle of the collision and may represent the time of locking of the subduction system and a post 4 5 ma phase of uplift unroofing and further diapirism in response to isostatic rebound our conclusions offer an alternative model for the evolution of this part of the banda arc

the 2020 mw 6 8 elazig turkey earthquake reveals rupture behavior of the east anatolian fault the 2020 mw 6 8 elazig earthquake was the largest along the eastern anatolian fault eaf in over a century and so provides valuable insights into its rupture behavior because the eaf is of low to

how well do surface slip measurements track slip at depth in large strike slip earthquakes the importance of fault structural maturity in controlling on fault slip versus off fault surface deformation abstract comparisons of observed surface displacements with geodetically inferred slip at depth in six large m w 7 1 strike slip earthquakes reveal a correlation between the structural maturity of the fault and the ratio of deep slip to surface slip that occurs on localized zones of surface rupture specifically structurally immature faults 25 km of total displacement manifest only 50 60 of total slip on narrow fault surface traces versus 85 95 for structurally mature faults 85 km total slip the same pattern holds when structurally simple parts of a surface rupture are analyzed separately from parts that exhibit obvious structural complexity e g discontinuous or multiple traces or significant dip slip these results imply that geologic measurements of surface slip along structurally immature faults are likely to significantly underestimate the true slip at depth in large earthquakes this observation has implications for a number of important problems including determination of fault slip rates which are based on surface offsets earthquake probability assessments which are based on geologic fault slip rates comparisons of geologic and geodetic rate data in the search for strain transients the structural evolution of fault zones estimation of paleo earthquake magnitudes based on geomorphic offsets analyses of the relative importance of faulting vs distributed deformation in accommodating relative plate motions in continental crust the design and construction of infrastructure built near active faults and possibly for the prediction of strong ground motions which may at least partially depend on the degree of slip localization to the surface

on the derivation of coseismic displacement fields using differential radar interferometry the landers earthquake we present a map of the coseismic displacement field resulting from the landers california june 28 1992 earthquake derived using data acquired from an orbiting high resolution radar system we achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques data from the ers 1 synthetic aperture radar instrument acquired in april july and august 1992 are used to generate a high resolution wide area map of the displacements the data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30 m resolution element in a 113 km by 90 km image our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing comparison of these data with global positioning system and electronic distance measurement survey data yield a correlation of 0 96 thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format the technique we use is 1 more automatic 2 more precise and 3 better validated than previous similar applications of differential radar interferometry since we require only remotely sensed satellite data with no additional requirements for ancillary information the technique is well suited for global seismic monitoring and analysis

the complete 3 d surface displacement field in the epicentral area of the 1999 mw7 1 hector mine earthquake california from space geodetic observations we use interferometric synthetic aperture radar insar data to derive continuous maps for three orthogonal components of the co seismic surface displacement field due to the 1999 m w7 1 hector mine earthquake in southern california vertical and horizontal displacements are both predominantly antisymmetric with respect to the fault plane consistent with predictions of linear elastic models of deformation for a strike slip fault some deviations from symmetry apparent in the surface displacement data may result from complexity in the fault geometry

lateral offsets on surveyed cultural features resulting from the 1999 izmit and duzce earthquakes turkey surveys of offset linear cultural features that cross the surface ruptures of the 17 august and 12 november 1999 earthquakes on the north anatolian fault in turkey yield slip values as large as or larger than those recorded by near field measurements in the same areas immediately after the earthquake using long linear alignments of trees fence lines walls and canals we demonstrate as much as a 2 m increase in observed slip over the initial field measurements on an average we observed about 15 of the total lateral slip as off fault deformation with values ranging from 0 to 40 of the total slip part of this lateral deformation is accom modated by bending or drag in a zone as much as 30 m in width although usually the zone varies between 5 and 20 m in width this supports the idea that substantial nonbrittle off fault deformation is associated with ruptures in areas of alluvial fill alternatively there may have been substantial afterslip although none has been recognized on postearthquake repaired structures our observations suggest that post earthquake measurements of fault slip using tape measures on offset geomorphic features may underestimate the actual amount of slip in that event where the non linearity of the offset feature does not allow recognition of the warping surveys of multiple tree lines within groves of poplar trees planted in straight lines across the fault prior to the earthquake show surprisingly large lateral varia tions in one grove slip increases by nearly 1 8 m or 35 of the maximum measured value over a lateral distance of nearly 100 m this and other observations along the 1999 ruptures suggest that the lateral variability of slip observed from displaced geomorphic features in many earthquakes of the past may represent a combination of 1 actual differences in slip at the surface and 2 the difficulty in recognizing distributed nonbrittle deformation

a physical model of the effect of a shallow weak layer on strong ground motion for strike slip ruptures we report results of foam rubber modeling of the effect of a shallow weak layer on ground motion from strike slip ruptures computer modeling of strong ground motion from strike slip earthquakes has involved somewhat arbitrary assumptions about the nature of slip along the shallow part of the fault e g fixing the slip to be zero along the upper 2 kilometers of the fault plane in order to match certain strong motion accelerograms most modeling studies of earthquake strong ground motion have used what is termed kinematic dislocation modeling in kinematic modeling the time function for slip on the fault is prescribed and the response of the layered medium is calculated unfortunately there is no guarantee that the model and the prescribed slip are physically reasonable unless the true nature of the medium and its motions are known ahead of time there is good reason to believe that in many cases faults are weak along the upper few kilometers of the fault zone and may not be able to maintain high levels of shear strain required for high dynamic energy release during earthquakes physical models of faulting as distinct from numerical or mathematical models are guaranteed to obey static and dynamic mechanical laws foam rubber modeling studies have been reported in a number of publications the object of this paper is to present results of physical modeling using a shallow weak layer in order to verify the physical basis for assuming a long rise time and a reduced high frequency pulse for the slip on the shallow part of faults it appears a 2 kilometer deep weak zone along strike slip faults could indeed reduce the high frequency energy radiated from shallow slip and that this effect can best be represented by superimposing a small amplitude short rise time pulse at the onset of a much longer rise time slip a weak zone was modeled by inserting weak plastic layers of a few inches in thickness into the foam rubber model for the 15 cm weak zone the average pulse is reduced by a factor of 0 46 the factor for the 20 cm case reduction is 0 11 for the 30 cm case it is 0 045 from these results we can see that the thicker the weak layer the more difficult it is for a short rise time acceleration pulse to push its way through the weak layer to the surface this is thus an approximate justification for reducing the high frequency radiation from shallower parts of strike slip faults if it is known that the shallow part of the fault is weak or has not stored up shear stress

comparison of coseismic near field and off fault surface deformation patterns of the 1992 mw 7 3 landers and 1999 mw 7 1 hector mine earthquakes implications for controls on the distribution of surface strain sub pixel correlation of pre and post event air photos reveal the complete near field horizontal surface deformation patterns of the 1992 m w 7 3 landers and 1999 m w 7 1 hector mine ruptures total surface displacement values for both earthquakes are systematically larger than on fault displacements from geologic field surveys indicating significant distributed inelastic deformation occurred along these ruptures comparison of these two datasets show 46 10 and 39 22 of the total surface deformation was distributed over fault zones averaging 154 m and 121 m in width for the landers and hector mine events respectively spatial variations of distributed deformation along both ruptures show correlations with the type of near surface lithology and degree of fault complexity larger amounts of distributed shear occur where the rupture propagated through loose unconsolidated sediments and areas of more complex fault structure these results have basic implications for geologic geodetic rate comparisons and probabilistic seismic hazard analysis

on going orogeny in the outer arc of the timor tanimbar region eastern indonesia abstract the timor tanimbar islands of eastern indonesia form a non volcanic arc in front of a 7 km deep fore arc basin that separates it from a volcanic inner arc the timor tanimbar islands expose one of the youngest high p t metamorphic belts in the world providing us with an excellent opportunity to study the inception of orogenic processes undisturbed by later tectonic events structural and petrological studies of the high p t metamorphic belt show that both deformation and metamorphic grade increase towards the centre of the 1 km thick crystalline belt kinematic indicators exhibit top to the north sense of shear along the subhorizontal upper boundaries and top to the south sense in the bottom boundaries of the high p t metamorphic belt overall configuration suggests that the high p t metamorphic rocks extruded as a thin sheet into a space between overlying ophiolites and underlying continental shelf sediments petrological study further illustrates that the central crystalline unit underwent a barrovian type overprint of the original high p t metamorphic assemblages during wedge extrusion and the metamorphic grade ranged from pumpellyite actinolite to upper amphibolite facies quaternary uplift marked by elevation of recent reefs was estimated to be about 1260 m in timor in the west and decreases toward tanimbar in the east in contrast radiometric ages for the high p t metamorphic rocks suggest that the exhumation of the high p t metamorphic belt started in western timor in late miocene time and migrated toward the east thus the tectonic evolution of this region is diachronous and youngs to the east we conclude that the deep seated high p t metamorphic belt extrudes into shallow crustal levels as a first step followed by doming at a later stage the so called mountain building process is restricted to the second stage we attribute this quaternary rapid uplift to rebound of the subducting australian continental crust beneath timor after it achieved positive buoyancy due to break off of the oceanic slab fringing the continental crust in contrast tanimbar in the east has not yet been affected by later doming a wide spectrum of processes starting from extrusion of the high p t metamorphic rocks and ending with the later doming due to slab break off can be observed in the timor tanimbar region

quantifying near field and off fault deformation patterns of the 1992 mw 7 3 landers earthquake coseismic surface deformation in large earthquakes is typically measured using field mapping and with a range of geodetic methods e g insar lidar differencing and gps current methods however either fail to capture patterns of near field coseismic surface deformation or lack preevent data consequently the characteristics of off fault deformation and the parameters that control it remain poorly understood we develop a standardized method to fully measure the surface near field coseismic deformation patterns at high resolution using the cosi corr program by correlating pairs of aerial photographs taken before and after the 1992 m w 7 3 landers earthquake cosi corr offers the advantage of measuring displacement across the entire zone of surface deformation and over a wider aperture than that available to field geologists for the landers earthquake our measured displacements are systematically larger than the field measurements indicating the presence of off fault deformation we show that 46 of the total surface displacement occurred as off fault deformation over a mean deformation width of 154 m the magnitude and width of off fault deformation along the rupture is primarily controlled by the macroscopic structural complexity of the fault system with a weak correlation with the type of near surface materials through which the rupture propagated both the magnitude and width of distributed deformation are largest in stepovers bends and at the southern termination of the surface rupture we find that slip along the surface rupture exhibits a consistent degree of variability at all observable length scales and that the slip distribution is self affine fractal with dimension of 1 56

sediment discharge and export of fluvial carbon and nutrients into the arafura and timor seas a regional synthesis abstract the arafura and timor seas ats are a crucial link between the indian and pacific oceans and play a vital role in global ocean circulation and climate some high standing islands in the ats are globally significant sources of sediment here we derive a synthesis of river catchments and their role as sources of water sediment carbon and nutrients to estimate the pathways magnitude and fate of exported riverine materials the edge of the australian continental shelf and slope receives riverine sediment from asia as isotopes suggest a mixing of sediment sources with some overlap between the australian and non australian material including evidence of significant input of volcanic material from indonesia the catchments bordering both the arafura and timor seas account for 12 of sediment and 35 of water discharged from tropical asia northern australia discharges a volume of freshwater comparable to southwest new guinea but 50 65 of total sediment 754 mt dic 61 1 mt poc 7 9 mt doc 3 5 mt tn 2 88 mt and tp 254 264 t delivered annually to the ats come from new guinea the island of timor discharges much smaller amounts of water 170 km 3 yr 1 and sediment 133 mt yr 1 but area specific rates of dic 1150 t km 2 yr 1 poc 238 t km 2 yr 1 doc 94 t km 2 yr 1 tn 61 t km 2 yr 1 and tp 4 4 t km 2 yr 1 are higher reflecting very high rates of deforestation and land degradation compared to other tropical rivers carbon export into the ats is dominated by dic the ats catchments are being increasingly affected by human activities and material discharge to the continental margins will likely increase impacting shelf communities and highly diverse reef mangrove and seagrass habitats

middle jurassic radiolaria from a siliceous argillite block in a structural melange zone near viqueque timor leste paleogeographic implications abstract thin bedded siliceous argillite forming a large block within a structural melange zone at viqueque timor leste has yielded a middle jurassic late bathonian early callovian radiolarian assemblage belonging to unitary association zone 7 fifty five species are recognized and illustrated forming the most diverse radiolarian fauna yet documented from the jurassic of timor the fauna shows little similarity in species content to the few other assemblages previously listed from the middle or late jurassic of timor and also has few species in common with faunas known elsewhere in the region from rotti sumatra south kalimantan and sula based on lithofacies similarities and age the siliceous argillite succession in the melange block at viqueque is included in the noni group originally described as the lower part of the palelo series in west timor in terms of lithofacies the noni group is distinct from other stratigraphic units known in timor it may be associated with volcanic rocks but age relationships are uncertain although some of the radiolarian cherts in the noni group in west timor have been reported to include tuffaceous sediment the deep water character of the siliceous hemipelagite pelagite facies the probable volcanic association and an age close to that of continental breakup in the region suggest deposition in a newly rifted indian ocean in timor s tectonostratigraphic classification scheme the noni group is here placed in the indian ocean megasequence

deformation of the cablac mountain range east timor an overthrust stack derived from an australian continental terrace the cablac mountain range in central east timor comprises a thrust stack of gondwana megasequence rocks of mainly triassic to jurassic age this southerly directed thrust stack occurs in structural contact with the underlying lolotoi formation and both the lolotoi formation and the overlying gondwanan thrust stack appear to be structurally emplaced upon younger mid eocene units to the south in addition the cablac thrust stack is bound to the north by a high angle fault along which a crush breccia comprising clasts from both the gondwana megasequence and asian banda terrane occurs this interpretation of the cablac mountain range differs significantly from previous interpretations in which the cablac limestones were suggested to be massive miocene limestones that occurred in depositional contact with underlying units

provenance of permian triassic gondwana sequence units accreted to the banda arc in the timor region constraints from zircon u pb and hf isotopes abstract analysis of zircons from australian affinity permian triassic units of the timor region yield age distributions with large age peaks at 230 400 ma and 1750 1900 ma which are similar to zircon age spectra found in rocks from ne australia and crustal fragments now found in tibet and se asia it is likely that these terranes which are now widely separated were once part of the northern edge of gondwana near what is now the northern margin of australia the cimmerian block rifted from gondwana in the early permian during the initial formation of the neo tethys ocean the zircon age spectra of the gondwana sequence of ne australia and in the timor region are most similar to the terranes of northern tibet and malaysia further substantiating a similar tectonic affinity a large 1750 1900 ma zircon peak is also very common in other terranes in se asia hf analysis of zircon from the aileu complex in timor and kisar islands shows a bimodal distribution both radiogenically enriched and depleted in the gondwana sequence at 300 ma the magmatic event from which these zircons were derived was likely bimodal i e mafic and felsic this is substantiated by the presence of permian mafic and felsic rocks interlayered with the sandstone used in this study similar rock types and isotopic signatures are also found in permian triassic igneous units throughout the cimmerian continental block the permian triassic rocks of the timor region fill syn rift intra cratonic basins that successfully rifted in the jurassic to form the nw margin of australia this passive continental margin first entered the sunda trench in the timor region at around 7 8 ma causing the permo triassic rocks to accrete to the edge of the asian plate and emerge as a series of mountainous islands in the young banda collision zone eventually the australian continental margin will collide with the southern edge of the asian plate and these gondwanan terranes will rejoin

arc parallel extrusion of the timor sector of the banda arc continent collision structural studies of synorogenic basins in timor using field and remote sensing techniques provide new structural and geomorphic evidence for syn collisional extension in the converging plate boun

coseismic and postseismic deformation of the 2016 mw 6 2 lampa earthquake southern peru constrained by interferometric synthetic aperture radar

detection of crustal deformation from the landers earthquake sequence using continuous geodetic measurements the measurement of crustal motions in technically active regions is being performed increasingly by the satellite based global positioning system gps 1 2 which offers considerable advantages over conventional geodetic techniques3 4 continuously operating gps arrays with ground based receivers spaced tens of kilometres apart have been established in central japan5 6 and southern california to monitor the spatial and temporal details of crustal deformation here we report the first measurements for a major earthquake by a continuously operating gps network the permanent gps geodetic array pgga 7 9 in southern california the landers magnitude afw of 7 3 and big bear mw 6 2 earthquakes of 28 june 1992 were monitored by daily observations ten weeks of measurements centred on the earthquake events indicate significant coseismic motion at all pgga sites significant post seismic motion at one site for two weeks after the earthquakes and no significant preseismic motion these measurements demonstrate the potential of gps monitoring for precise detection of precursory and aftershock seismic deformation in the near and far field

the structural setting and tectonic significance of the lolotoi laclubar and aileu metamorphic massifs east timor abstract the lolotoi and laclubar metamorphic massifs of east timor form a part of the lolotoi metamorphic complex based on stratigraphic relationships with the australian affinity parautochthonous stratigraphic succession and structural arguments the lolotoi complex is interpreted as representing australian continental basement entrained into the timor arc continent collision complex by basement involved thrusting the lolotoi complex is not synonymous with the mutis complex defined from west timor which represents allochthonous metamorphic basement derived from the pre collisional banda forearc the aileu complex is a syn collisional metamorphic series with an inverted metamorphic gradient developed beneath overthrust allochthonous peridotite

off fault deformations and shallow slip deficit from dynamic rupture simulations with fault zone plasticity kinematic source inversions of major m 7 strike slip earthquakes show that the slip at depth exceeds surface displacements measured in the field and it has been suggested that this shallow slip deficit ssd is caused by distributed plastic deformation near the surface we perform dynamic rupture simulations of m 7 2 7 4 earthquakes in elastoplastic media and analyze the sensitivity of ssd and off fault deformation ofd to rock quality parameters while linear simulations clearly underpredict observed ssd and ofds nonlinear simulations for a moderately fractured fault damage zone predict a ssd of 44 53 and ofds of 39 48 consistent with the 30 60 ssd and 46 10 1 ofd reported for the 1992 m 7 3 landers earthquake both ssd and ofds are sensitive to the quality of the fractured rock mass inside the fault damage zone and surface rupture is almost entirely suppressed in poor quality material

space imaging geodesy reveals near circular coseismic block rotation during the 2016 mw 7 8 kaikōura earthquake new zealand

resolving the kinematics and moment release of early afterslip within the first hours following the 2016 mw 7 1 kumamoto earthquake implications for the shallow slip deficit and frictional behavior of aseismic creep continuous measurements of postseismic surface deformation provide insight into variations of the frictional strength of faults and the rheology of the lower crust and upper mantle as stresses following rupture are dissipated however due to the difficulty of capturing the earliest phase of afterslip most analyses have focused on understanding postseismic processes over timescales of weeks to years here we investigate the kinematics moment release and frictional properties of the earliest phase of afterslip within the first hours following the 2016 m w 7 1 kumamoto earthquake using a network of five minute sampled continuous gps stations using independent component analysis to filter the gps data we find that 1 early afterslip contributes only 1 of total moment release within the first hour and 8 after 24 hours this suggests that the slip model of the mainshock which we estimate using standard geodetic datasets e g insar gps and pixel offsets and which span the first four days of the postseismic period is largely reflective of the dynamic rupture process and we can rule out contamination of moment release by early afterslip 2 early afterslip shows no evidence of a delayed nucleation or acceleration phase where instead fault patches transition to immediate deceleration following rupture that is consistent with frictional relaxation under steady state conditions with dependence only on the sliding velocity 3 there is a close correlation between the near field aftershocks and afterslip within the first hours following rupture suggesting afterslip may still be an important possible triggering mechanism during the earliest postseismic period

coseismic deformation from the 1999 mw 7 1 hector mine california earthquake as inferred from insar and gps observations we use interferometric synthetic aperture radar insar and global positioning system gps observations to investigate static deformation due to the 1999 m w 7 1 hector mine earthquake that occurred in the eastern california shear zone interferometric decorrelation phase and azimuth offset measurements indicate regions of surface and near surface slip which we use to constrain the geometry of surface rupture the inferred geometry is spatially complex with multiple strands the southern third of the rupture zone consists of three subparallel segments extending about 20 km in length in a n45 w direction the central segment is the simplest with a single strand crossing the bullion mountains and a strike of n10 w the northern third of the rupture zone is characterized by multiple splays with directions subparallel to strikes in the southern and central the average strike for the entire rupture is about n30 w the interferograms indicate significant along strike variations in strain which are consistent with variations in the ground based slip measurements using a variable resolution data sampling routine to reduce the computational burden we invert the insar and gps data for the fault geometry and distribution of slip we compare results from assuming an elastic half space and a layered elastic space results from these two elastic models are similar although the layered space model predicts more slip at depth than does the half space model the layered model predicts a maximum coseismic slip of more than 5 m at a depth of 3 to 6 km contrary to preliminary reports the northern part of the hector mine rupture accommodates the maximum slip our model predictions for the surface fault offset and total seismic moment agree with both field mapping results and recent seismic models the inferred shallow slip deficit is enigmatic and may suggest that distributed inelastic yielding occurred in the uppermost few kilometers of the crust during or soon after the earthquake

re evaluation of the cablac limestone at its type area east timor revision of the miocene stratigraphy of timor abstract the cablac limestone widely recorded in timor has its type area on cablac mountain where it was regarded as a lower miocene shallow marine carbonate platform succession the bahaman like facies placed in the cablac limestone are now known to belong to the upper triassic lower jurassic rather than the lower miocene on the northern slopes of cablac mountain a crush breccia formerly regarded as the basal conglomerate of the formation is now considered to have developed along a high angle fault separating banda terrane units of asian affinity from an overthrust limestone stack containing units belonging to the gondwana and australian margin megasequences the cablac breccia includes rock fragments that were probably derived locally from these tectonostratigraphic units after terrane emplacement and overthrusting clasts include peloid and oolitic limestones of the upper triassic lower jurassic derived from the gondwana megasequence deep water carbonate pelagites of the cretaceous and paleogene derived from the australian margin megasequence upper oligocene lower miocene te letter stage shallow water limestone derived from the banda terrane and a younger neogene calcarenite containing clasts of mixed tectonostratigraphic affinity there is no evidence for significant sedimentary or tectonic transport of clasts that form the breccia the clast types and the present understanding of the geological history of timor suggest that the crush breccia formed late in the plio pleistocene uplift history of timor it is not the basal conglomerate of the cablac limestone however the clasts of an upper oligocene lower miocene limestone found in the breccia suggest that a shallow marine limestone unit of this age either outcrops in the region and has not been detected in the field or has been eroded completely during late neogene uplift the clasts are similar in age and lithology to an upper oligocene lower miocene formation that unconformably overlies a metamorphic complex in the booi region of west timor similar to the lolotoi metamorphic complex banda terrane that is juxtaposed against the crush breccia of cablac mountain the cablac limestone at its type area includes a mixed assemblage of carbonate rock units ranging in age from triassic to plio pleistocene and representing diverse facies as a formation the name cablac limestone should be discarded for a cenozoic unit the upper oligocene lower miocene shallow water limestone unit that is typified by outcrops in the booi region of west timor and that has contributed to clasts in the cablac breccia is informally named the booi limestone it is considered part of the allochthonous banda terrane of asian affinity and represents the only shallow marine lower miocene unit known from timor the only other miocene sedimentary unit known from timor includes carbonate pelagites designated the kolbano beds probably deposited on an australian continental terrace at water depths between 1000 and 3000 m on the northeastern edge of cablac mountain oolitic limestone and associated units of the gondwana megasequence the kolbano beds of the australian margin megasequence and the booi limestone and associated metasediments of the banda terrane were juxtaposed by a plio pleistocene high angle fault along which the cablac crush breccia formed

coseismic slip model of the 2008 wenchuan earthquake derived from joint inversion of interferometric synthetic aperture radar gps and field data 1 we derived a coseismic slip model for the mw 7 9 2008 wenchuan earthquake on the basis of radar line of sight displacements from alos interferograms gps vectors and geological field data available interferometric synthetic aperture radar insar data provided a nearly complete coverage of the surface deformation along both ascending fine beam mode and descending orbits scansar to scansar mode the earthquake was modeled using four subfaults with variable geometry and dip to capture the simultaneous rupture of both the beichuan fault and the pengguan fault our model misfits show that the insar and gps data are highly compatible the combined inversion yields a 93 variance reduction the best fit model has fault planes that rotate from shallow dip in the south 35 to nearly vertical dip toward the north 70 our rupture model is complex with variations in both depth and rake along two major fault strands in the southern segment of the beichuan fault the slip is mostly thrust 13 m and occurred principally in the upper 10 km of the crust the rupture progressively transformed to right lateral strike slip as it propagated northeast with maximum offsets of 7 m our model suggests that most of the moment release was limited to the shallow part of the crust depth less than 10 km we did not find any shallow slip deficit in the slip depth distribution of this mixed mechanism earthquake aftershocks were primarily distributed below the section of the fault that ruptured coseismically

a bayesian method for incorporating self similarity into earthquake slip inversions distributions of coseismic slip help illuminate many properties of earthquakes including fault geometry stress changes frictional properties and potential future hazard slip inversions take observations and calculate slip at depth but there are a number of commonly adopted assumptions such as minimizing the second spatial derivative of slip the laplacian that have little physical basis and potentially bias the result in light of growing evidence that fault slip shows fractal properties we suggest that this information should be incorporated into slip inversions as a form of regularization instead of laplacian smoothing we have developed a bayesian approach to efficiently solve for slip incorporating von karman regularization in synthetic tests our approach retrieves fractal slip better than laplacian regularization as expected but even performs comparably or better when the input slip is not fractal we apply this to the 2014 mw 6 0 napa valley earthquake on a two segment fault using interferometric synthetic aperture radar insar and global positioning system gps data we find the von karman and laplacian inversions give similar slip magnitude but in different locations and the von karman solution has much tighter confidence bounds on slip than the laplacian solution differences in earthquake slip due to the regularization technique could have important implications for the interpretation and modeling of stress changes on the causative and neighboring faults we therefore recommend that choice of regularization method should be routinely made explicit and justified and that von karman regularization is a better default than laplacian