shallow creep on the haiyuan fault gansu china revealed by sar interferometry interferometric synthetic aperture radar data are used to map the interseismic velocity field along the haiyuan fault system hfs at the north eastern boundary of the tibetan plateau two m 8 earthquakes ruptured the hfs in 1920 and 1927 but its 260 km long central section known as the tianzhu seismic gap remains unbroken since 1000 years the envisat sar data spanning the 2003 2009 period cover about 200 300 km2 along three descending and two ascending tracks interferograms are processed using an adapted version of roi pac the signal due to stratified atmospheric phase delay is empirically corrected together with orbital residuals mean line of sight velocity maps are computed using a constrained time series analysis after selection of interferograms with low atmospheric noise these maps show a dominant left lateral motion across the hfs and reveal a narrow 35 km long zone of high velocity gradient across the fault in between the tianzhu gap and the 1920 rupture we model the observed velocity field using a discretized fault creeping at shallow depth and a least squares inversion the inferred shallow slip rate distribution reveals aseismic slip in between two fully locked segments the average creep rate is 5 mm yr 1 comparable in magnitude with the estimated loading rate at depth suggesting no strain accumulation on this segment the modeled creep rate locally exceeds the long term rate reaching 8 mm yr 1 suggesting transient creep episodes the present study emphasizes the need for continuous monitoring of the surface velocity in the vicinity of major seismic gaps in terms of seismic hazard assessment

systematic comparisons of earthquake source models determined using insar and seismic data abstract robust earthquake source parameters e g location seismic moment fault geometry are essential for reliable seismic hazard assessment and the investigation of large scale tectonics they are routinely estimated using a variety of data and techniques such as seismic data and more recently interferometric synthetic aperture radar insar comparisons between these two datasets are frequently made although not usually in a comprehensive way this review compares source parameters from global and regional seismic catalogues with those from a recent database of insar parameters which has been expanded with 18 additional source models for this study we show that moment magnitude mw estimates agree well between the two datasets with a trend for thrust events modelled using insar to have slightly larger mw estimates earthquake locations determined using insar agree well with those reported in regional catalogues with a median difference of 6 3 km between them which is smaller than for global seismic catalogues we also investigate the consistency of source parameters and source directivity by comparing isc hypocentres with gcmt and icmt centroid locations for earthquakes with mw 6 5 in some cases the source directivity is qualitatively comparable with previous studies especially when comparing isc and icmt locations the average difference between insar determined depths and those in the ehb catalogue is reduced if a layered half space is used in the inversion of insar data overall faulting geometry strike dip and rake angles remain in good agreement with values from the gcmt catalogue and any large discrepancies can be attributed to tradeoffs between parameters with continued investment in satellites for radar interferometry insar is a valuable technique for the estimation of earthquake source parameters the observed trends and discrepancies between insar and seismically determined source parameters are the result of issues with the data different inversion techniques and the assumed earth structure model

source parameters of the 2014 mw 6 1 south napa earthquake estimated from the sentinel 1a cosmo skymed and gps data abstract using the combination of two insar and one gps data sets we present the detailed source model of the 2014 mw 6 1 south napa earthquake the biggest tremor to hit the san francisco bay area since the 1989 mw 6 9 loma prieta earthquake the insar data are from the sentinel 1a s1a and cosmo skymed cs satellites and gps data are provided by nevada geodetic laboratory we firstly obtain the complete coseismic deformation fields of this event and estimate the insar data errors then using the s1a data to construct the fault geometry one main and two short parallel sub faults which haven t been identified by field investigation as expected the geometry is in good agreement with the aftershock distribution by inverting the insar and gps data we derive a three segment slip and rake models our model indicates that this event was a right lateral strike slip earthquake with a slight reverse component in the west napa fault as we estimated the fault is 30 km long and more than 80 of the seismic moment was released at the center of the fault segment where the slip reached its maximum up to 1 m we also find that our geodetic moment magnitude is 2 07 1018 nm corresponding to mw 6 18 larger than that of usgs mw 6 0 and gcmt mw 6 1 this difference may partly be explained by our insar data including about one week s postseismic deformation and aftershocks the results also demonstrate high snr and great ability of the newly launched sentinel 1a in earthquake study furthermore this study suggests that this earthquake has potential to trigger nearby faults especially the green valley fault where the coulomb stress was imparted by the 2014 south napa earthquake

covariance estimation for dinsar surface deformation measurements in the presence of anisotropic atmospheric noise we study anisotropic spatial autocorrelation in differential synthetic aperture radar interferometric dinsar measurements and its impact on geophysical parameter estimations the dinsar phase acquired by the satellite sensor is a superposition of different contributions and when studying geophysical processes we are usually only interested in the surface deformation part of the signal therefore to obtain high quality results we would like to characterize and or remove other phase components a stochastic model has been found to be appropriate to describe atmospheric phase delay in dinsar images however these phase delays are usually modeled as being isotropic which is a simplification because insar images often show directional atmospheric anomalies here we analyze anisotropic structures and show validation results using both real and simulated data we calculate experimental semivariograms of the dinsar phase in several european remote sensing satellite 1 2 tandem interferograms based on the theory of random functions rfs we then fit anisotropic variogram models in the spatial domain employing mate rn and bessel family correlation functions in nested models to represent complex dinsar covariance structures the presented covariance function types in the statistical framework of stationary rfs are consistent with tropospheric delay models we find that by using anisotropic data covariance information to weight dinsar measurements we can significantly improve both the precision and accuracy of geophysical parameter estimations furthermore the improvement is dependent on how similar the deformation pattern is to the dominant structure of the anisotropic atmospheric signals

chilean megathrust earthquake recurrence linked to frictional contrast at depth fundamental processes of the seismic cycle in subduction zones including those controlling the recurrence and size of great earthquakes are still poorly understood here by studying the 2016 earthquake in southern chile the first large event within the rupture zone of the 1960 earthquake moment magnitude mw 9 5 we show that the frictional zonation of the plate interface fault at depth mechanically controls the timing of more frequent moderate size deep events mw 8 5 we model the evolution of stress build up for a seismogenic zone with heterogeneous friction to examine the link between the 2016 and 1960 earthquakes our results suggest that the deeper segments of the seismogenic megathrust are weaker and interseismically loaded by a more strongly coupled shallower asperity deeper segments fail earlier 60 yr recurrence producing moderate size events that precede the failure of the shallower region which fails in a great earthquake recurrence 110 yr we interpret the contrasting frictional strength and lag time between deeper and shallower earthquakes to be controlled by variations in pore fluid pressure our integrated analysis strengthens understanding of the mechanics and timing of great megathrust earthquakes and therefore could aid in the seismic hazard assessment of other subduction zones the recurrence time of megathrust earthquakes in chile may be controlled by frictional contrasts at depth according to analyses of stress build up and release related to the december 2016 southern chile earthquake

plate boundary deformation in north iceland during 1992 2009 revealed by insar time series analysis and gps abstract in north iceland extensional plate motion is accommodated by the northern volcanic zone a set of en echelon volcanic systems and the tjornes fracture zone a transform offset in the mid atlantic ridge consisting of two parallel transform lineaments the southern lineament the husavik flatey fault is a 100 km long right lateral strike slip fault that has not ruptured for more than 140 years and poses a significant seismic hazard to husavik a fishing town located by the fault and to other coastal communities we present results of insar time series analysis data spanning almost two decades 1992 2009 that show extensional and interseismic deformation within the northern volcanic zone and the on shore part of the tjornes fracture zone the results also exhibit transient inflation at theistareykir volcano deflation at krafla central volcano and a broad uplift north of krafla the current plate extension is not uniform across the northern volcanic zone but concentrated at the western fissures of the theistareykir volcanic system and the outermost fissures of the krafla fissure swarm we combine a back slip plate boundary model with a set of point pressure sources representing volcanic changes to describe the current extensional plate boundary deformation and update the previous estimations of the locking depth and slip rate of the husavik flatey fault that were based on gps data alone using different combinations of input data we find that the husavik flatey fault has a locking depth of 6 10 km and with a slip rate of 6 9 mm yr is accommodating about a third of the full transform motion we furthermore show that while the insar data provide important constraints on the volcanic deformation within the nvz they do not significantly improve the model parameter estimation for the hff as the dense gps network appears to better capture the deformation across the fault

coseismic stress changes and crustal deformation on the reykjanes peninsula due to triggered earthquakes on 17 june 2000 1 a large mw 6 5 earthquake struck the south iceland seismic zone sisz on 17 june 2000 the 17 june main shock triggered increased seismicity over a large area and significant slip on at least three distinct faults on the reykjanes peninsula up to 87 km to the west of the event a second large mw 6 4 earthquake in the sisz occurred on 21 june 2000 about 17 km west of the 17 june main shock this event does not appear to have triggered as much activity on the reykjanes peninsula as the 17 june main shock although the epicenter was closer crustal deformation signals due to the june 2000 earthquakes on the reykjanes peninsula were observed with campaign and continuous gps and synthetic aperture radar interferometry with the largest coseismic deformation signal near lake kleifarvatn we model the faults using three uniform slip rectangular dislocations in an elastic half space best fit uniform slip models consistent with seismic and geodetic data indicate that all three faults trend n s and the motion on them was primarily right lateral strike slip our study suggests that the event near kleifarvatn had a significantly larger moment than seismic estimates indicating a component of aseismic slip on the fault lasting no more than several hours static coulomb failure stress change calculations indicate that the event at kleifarvatn increased the coulomb stress at the hypocenter of the nupshlidarhals event by 0 1 0 2 mpa as well as loading the hvalhnukur fault

joint earthquake source inversions using seismo geodesy and 3 d earth models a joint earthquake source inversion technique is presented that uses insar and long period teleseismic data and for the first time takes 3 d earth structure into account when modelling seismic surface and body waves ten average source parameters moment latitude longitude depth strike dip rake length width and slip are estimated hence the technique is potentially useful for rapid source inversions of moderate magnitude earthquakes using multiple data sets unwrapped interferograms and long period seismic data are jointly inverted for the location fault geometry and seismic moment using a hybrid downhill powell monte carlo algorithm while the insar data are modelled assuming a rectangular dislocation in a homogeneous halfspace seismic data are modelled using the spectral element method for a 3 d earth model the effect of noise and lateral heterogeneity on the inversions is investigated by carrying out realistic synthetic tests for various earthquakes with different faulting mechanisms and magnitude mw 6 0 6 6 synthetic tests highlight the improvement in the constraint of fault geometry strike dip and rake and moment when insar and seismic data are combined tests comparing the effect of using a 1 d or 3 d earth model show that long period surface waves are more sensitive than long period body waves to the change in earth model incorrect source parameters particularly incorrect fault dip angles can compensate for systematic errors in the assumed earth structure leading to an acceptable data fit despite large discrepancies in source parameters three real earthquakes are also investigated eureka valley california 1993 may 17 mw 6 0 aiquile bolivia 1998 february 22 mw 6 6 and zarand iran 2005 may 22 mw 6 5 these events are located in different tectonic environments and show large discrepancies between insar and seismically determined source models despite the 40 50 km discrepancies in location between previous geodetic and seismic estimates for the eureka valley and aiquile earthquakes the seismic data are found to be compatible with the insar location a 30 difference in strike between insar and seismic derived source models is also resolved when taking 3 d earth structure into account in the analysis of the eureka valley earthquake the combination of both insar and seismic data further constrains the dip for the zarand earthquake and in all cases the seismic moment is more robustly constrained in the joint inversions than in the individual data set inversions unmodelled lateral heterogeneities in earth and the models could partly explain some of the observed source parameter discrepancies related to the seismic data the authors 2014 published by oxford university press on behalf of the royal astronomical society

use of psinsar data to infer active tectonics clues on the differential uplift across the giudicarie belt central eastern alps italy abstract the permanent scatterers synthetic aperture radar interferometry psinsar methodology provides high resolution assessment of surface deformations precision ranging from 0 8 to 0 1 mm year over long periods of observation hence it is particularly suitable to analyze surface motion over wide regions associated to a weak tectonic activity for this reason we have adopted the psinsar technique to study regional movement across the giudicarie belt a nne trending trust belt oblique to the southern alpine chain and presently characterized by a low to moderate seismicity over 11 000 ps velocities along the satellite line of sight los were calculated using images acquired in descending orbit during the 1992 1996 time span the psinsar data show a differential uplift of around 1 4 1 7 mm year across the most external wnw dipping thrusts of the giudicarie belt mt baldo mt stivo and mt grattacul thrusts alignment this corresponds to a horizontal contraction across the external part of the giudicarie belt of about 1 3 1 5 mm year

along strike variations of the partitioning of convergence across the haiyuan fault system detected by insar oblique convergence across tibet leads to slip partitioning with the coexistence of strike slip normal and thrust motion on major fault systems a key point is to understand and model how faults interact and accumulate strain at depth here we extract ground deformation across the haiyuan fault restraining bend at the northeastern boundary of the tibetan plateau from envisat radar data spanning the 2001 textendash2011 period we show that the complexity of the surface displacement field can be explained by the partitioning of a uniform deep seated convergence mountains and sand dunes in the study area make the radar data processing challenging and require the latest developments in processing procedures for synthetic aperture radar interferometry the processing strategy is based on a small baseline approach before unwrapping we correct for atmospheric phase delays from global atmospheric models and digital elevation model errors a series of filtering steps is applied to improve the signal to noise ratio across high ranges of the tibetan plateau and the phase unwrapping capability across the fault required for reliable estimate of fault movement we then jointly invert our insar time series together with published gps displacements to test a proposed long term slip partitioning model between the haiyuan and gulang left lateral faults and the qilian shan thrusts we explore the geometry of the fault system at depth and associated slip rates using a bayesian approach and test the consistency of present day geodetic surface displacements with a long term tectonic model we determine a uniform convergence rate of 10 8 6 textendash11 5 mm yr 1 with an n89 81 textendash97 e across the whole fault system with a variable partitioning west and east of a major extensional fault jog the tianzhu pull apart basin our 2 d model of two profiles perpendicular to the fault system gives a quantitative understanding of how crustal deformation is accommodated by the various branches of this thrust strike slip fault system and demonstrates how the geometry of the haiyuan fault system controls the partitioning of the deep secular motion

magma propagation at piton de la fournaise from joint inversion of insar and gnss magma propagation is an unsteady process controlled by magma crust interaction to provide information on its dynamics we invert complementary ground deformation data spanning the 8 hr preceding the 26 may 2016 eruption at piton de la fournaise pdf volcano la reunion france data are inverted using 3 d boundary element models combined with a monte carlo inversion method the final geometry of the displacement source is determined based on four interferograms spanning the whole propagation phase while the dynamics of the propagation is inferred from temporal inversion of continuous global navigation satellite system gnss data using the final geometry as an a priori to constrain the source the best modeled magma path consists in a 2 700 m long sill located 800 m above sea level and connected to the eruptive fissure by a subvertical dike the quick opening of the horizontal part of the intrusion could have been favored by limited flank sliding during the early stage of propagation the intrusion then stalled for 5 hr while pressure increased slightly until final upward propagation and eruption volume budget suggests that the eruption was fed by a single batch of magma quickly disconnected from its source the delay prior to the eruption may reflect a limited magma supply finally two mechanisms potentially acting together might have favored the eruption a driving role of magmatic gas and or as often observed at piton de la fournaise an eastward flank slip

toward mapping surface deformation in three dimensions using insar 1 one of the limitations of deformation measurements made with interferometric synthetic aperture radar insar is that an interferogram only measures one component of the surface deformation in the satellite s line of sight we investigate strategies for mapping surface deformation in three dimensions by using multiple interferograms with different imaging geometries geometries for both current and future missions are evaluated and their abilities to resolve the displacement vector are compared the north component is always the most difficult to determine using data from near polar orbiting satellites however a satellite with an inclination of about 60 120 would enable all three components to be well resolved we attempt to resolve the 3d displacements for the 23 october 2002 nenana mountain alaska earthquake the north component s error is much larger than the signal but proxies for eastward and vertical motion can be determined if the north component is assumed negligible inversions of hypothetical coseismic interferograms demonstrate that earthquake model parameters can be well recovered from two interferograms acquired on ascending and descending tracks

insar bias and uncertainty due to the systematic and stochastic tropospheric delay we quantify the bias and uncertainty of interferometric synthetic aperture radar insar displacement time series and their derivatives the displacement velocities by analyzing the systematic and stochastic components of the temporal variation of the tropospheric delay the biases due to the systematic seasonal delay depend on the sar acquisition times whereas the uncertainties depend on the standard deviation of the random delay the number of acquisitions the total time span covered and the covariance of the time series of the stochastic delay between a pixel and the reference we study the contribution of the wet delay to the insar observations along the western india plate boundary using i moderate resolution imaging spectroradiometer precipitable water vapor ii stratified tropospheric delay estimated from the era i global atmospheric model and iii seven envisat insar swaths our analysis indicates that the amplitudes of the annual delay vary by up to 10 cm in this region equivalent to a maximum displacement bias of 24 cm in insar line of sight direction between two epochs assuming envisat is6 beam mode the stratified tropospheric delay correction mitigates this bias and reduces the scatter due to the stochastic delay for 7 years of envisat acquisitions along the western india plate boundary the uncertainty of the insar velocity field due to the residual stochastic wet delay after stratified tropospheric delay correction using the era i model is in the order of 2 mm yr over 100 km and 4 mm yr over 400 km we discuss the implication of the derived uncertainties on the full variance covariance matrix of the insar data

distribution of aseismic slip rate on the hayward fault inferred from seismic and geodetic data 1 we solve for the slip rate distribution on the hayward fault by performing a least squares inversion of geodetic and seismic data sets our analysis focuses on the northern 60 km of the fault interferometric synthetic aperture radar insar data from 13 independent ers interferograms are stacked to obtain range change rates from 1992 to 2000 horizontal surface displacement rates at 141 bench marks are measured using gps from 1994 to 2003 surface creep observations and estimates of deep slip rates determined from characteristic repeating earthquake sequences are also incorporated in the inversion the fault is discretized into 283 triangular dislocation elements that approximate the nonplanar attributes of the fault surface south of the city of hayward a steeply east dipping fault geometry accommodates the divergence of the surface trace and the microseismicity at depth the inferred slip rate distribution is consistent with a fault that creeps aseismically at a rate of 5 mm yr to a depth of 4 6 km the interferometric synthetic aperture radar insar data require an aseismic slip rate that approaches the geologic slip rate on the northernmost fault segment beneath point pinole although the insar data might be complicated by a small dip slip component at this location a low slip rate patch of 1 mm yr is inferred beneath san leandro consistent with the source location of the 1868 earthquake we calculate that the entire fault is accumulating a slip rate deficit equivalent to a mw 6 77 0 05 per century however this estimate of potential coseismic moment represents an upper bound because we do not know how much of the accumulated strain will be released through aseismic processes such as afterslip

structural architecture of a highly oblique divergent plate boundary segment abstract the reykjanes peninsula in southwest iceland is a highly oblique spreading segment of the mid atlantic ridge oriented about 30 from the direction of absolute plate motion we present a complete and spatially accurate map of fractures for the reykjanes peninsula with a level of detail previously unattained our map reveals a variability in the pattern of normal oblique and strike slip faults and open fractures which reflects both temporal and spatial strain partitioning within the plate boundary zone fracture density varies across the length and width of the peninsula with density maxima at the ends and at the northern margin of the zone of volcanic activity fractures with similar strike cluster into distinct structural domains which can be related to patterns of faulting predicted for oblique extension and to their spatial distribution with respect to volcanic fissure swarms additional structural complexity on the reykjanes peninsula can be reconciled with magmatic periodicity and associated temporal strain partitioning implied by gps data as well as locally perturbed stress fields individual faults show variable slip histories indicating that they may be active during both magmatic and amagmatic periods associated with different strain fields

fault slip distribution of two june 2000 m w 6 5 earthquakes in south iceland estimated from joint inversion of insar and gps measurements abstract we present the first detailed estimates of co seismic slip distribution on faults in the south iceland seismic zone sisz an area of bookshelf tectonics we have estimated source parameters for two m w 6 5 earthquakes in the sisz on june 17 and 21 2000 through a joint inversion of insar and gps measurements our preferred model indicates two simple 15 km long near vertical faults extending from the surface to approximately 10 km depth the geometry is in good agreement with the aftershock distribution the dislocations experienced pure right lateral strike slip reaching maxima of 2 6 m and 2 9 m for the june 17 and 21 events respectively we find that the distribution of slip with depth may be correlated to crustal layering with more than 80 of the total geometric moment release occurring in the uppermost 6 km according to the distributed slip model the middle and upper crust appears to be more apt to generate large displacements than the lower crust the geodetic estimates of seismic moments are 4 4 10 18 nm m w 6 4 and 5 0 10 18 nm m w 6 5 the total moment released by the two events equals that generated by several decades of plate motion in the area but is only a fraction of the moment accumulated in the area since the last major earthquake in 1912

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

improved source modelling through combined use of insar and gps under consideration of correlated data errors application to the june 2000 kleifarvatn earthquake iceland summary simultaneous use of multiple independent data sets can improve constraints on earthquake source model parameters however the ways in which data sets have been combined in the past are manifold and usually qualitative in this paper we present a method to combine geodetic data in source model estimations which includes characterizing the data errors and estimating realistic model parameter uncertainties caused by these errors we demonstrate this method in a case study of the june 2000 kleifarvatn earthquake which occurred on reykjanes peninsula in iceland we begin by showing to what extent additional data can positively influence the source modelling results by combining both gps and descending orbit insar data which were used in two earlier studies of that event with insar data from an ascending orbit we estimate the data error covariances of the insar observations and base the data weights in our model parameter optimization on the corresponding data variance covariance matrix we also derive multiple sets of synthetic data errors from the estimated data covariances that we use to modify the original data to generate numerous data realizations from these data realizations we estimate the model parameter uncertainties we first model the kleifarvatn earthquake as a simple uniform slip fault and subsequently as a fault with variable slip and rake our fault model matches well with the field observations of coseismic surface ruptures and its near vertical dip 83 agrees with the regional faulting style as well as with aftershock locations the two published source models of the event on the other hand both differ from our model as well as differing for one another these studies which were based on the descending insar data alone the first study and on that same data and gps data the second study both neglect correlations in the insar data and do not report model parameter uncertainties therefore to compare these results with our model we simulate the earlier model estimation set ups and provide realistic estimates of the model parameters uncertainties for these cases we then discuss the significance of the difference between the existing fault models and demonstrate that both the inclusion of additional independent data as well as the covariance based data weights improve the model parameter estimation

finite element model predictions of static deformation from dislocation sources in a subduction zone sensitivities to homogeneous isotropic poisson solid and half space assumptions 1 dislocation models can simulate static deformation caused by slip along a fault these models usually take the form of a dislocation embedded in a homogeneous isotropic poisson solid half space hipshs however the widely accepted hipshs assumptions poorly approximate subduction zone systems of converging oceanic and continental crust this study uses three dimensional finite element models fems that allow for any combination including none of the hipshs assumptions to compute synthetic green s functions for displacement using the1995 mw 8 0 jalisco colima mexico subduction zone earthquake and associated measurements from a nearby gps array as an example fem generated synthetic green s functions are combined with standard linear inverse methods to estimate dislocation distributions along the subduction interface loading a forward hipshs model with dislocation distributions estimated from fems that sequentially relax the hipshs assumptions yields the sensitivity of predicted displacements to each of the hipshs assumptions for the subduction zone models tested and the specific field situation considered sensitivities to the individual poisson solid isotropy and homogeneity assumptions can be substantially greater than gps measurement uncertainties forward modeling quantifies stress coupling between the mw 8 0 earthquake and a nearby mw 6 3 earthquake that occurred 63 days later coulomb stress changes predicted from static hipshs models cannot account for the 63 day lag time between events alternatively an fem that includes a poroelastic oceanic crust which allows for postseismic pore fluid pressure recovery can account for the lag time the pore fluid pressure recovery rate puts an upper limit of 10 17 m2 on the bulk permeability of the oceanic crust

distribution of interseismic coupling along the north and east anatolian faults inferred from insar and gps data the north anatolian fault naf has produced numerous major earthquakes after decades of quiescence the mw 6 8 elazig earthquake january 24 2020 has recently reminded us that the east anatolia

from quiescence to unrest 20 years of satellite geodetic measurements at santorini volcano greece periods of unrest at caldera forming volcanic systems characterized by increased rates of seismicity and deformation are well documented some can be linked to eventual eruptive activity while others are followed by a return to quiescence here we use a 20 year record of interferometric synthetic aperture radar insar and gps measurements from santorini volcano to further our understanding of geodetic signals at a caldera forming volcano during the periods of both quiescence and unrest with measurements spanning a phase of quiescence and slow subsidence 1993 2010 followed by a phase of unrest january 2011 to april 2012 with caldera wide inflation and seismicity mean insar velocity maps from 1993 2010 indicate an average subsidence rate of 6 mm yr over the southern half of the intracaldera island nea kameni this subsidence can be accounted for by a combination of thermal contraction of the 1866 1870 lava flows and load induced relaxation of the substrate for the period of unrest we use a joint inversion technique to convert insar measurements from three separate satellite tracks and gps observations from 10 continuous sites into a time series of subsurface volume change the optimal location of the inflating source is consistent with previous studies situated north of nea kameni at a depth of 4 km however the time series reveals two distinct pressure pulses the first pulse corresponds to a volume change v within the shallow magma chamber of 11 56 0 14 106 m3 and the second pulse has a v of 9 73 0 10 106 m3 the relationship between the timing of these pulses and microseismicity observations suggests that these pulses may be driven by two separate batches of magma supplied to a shallow reservoir we find no evidence suggesting a change in source location between the two pulses the decline in the rates of volume change at the end of both pulses and the observed lag of the deformation signal behind cumulative seismicity suggest a viscoelastic response we use a simple model to show that two separate pulses of magma intruding into a shallow magma chamber surrounded by a viscoelastic shell can account for the observed temporal variation in cumulative volume change and seismicity throughout the period of unrest given the similarities between the geodetic signals observed here and at other systems this viscoelastic model has potential use for understanding behavior at other caldera systems

assessing the reliability and consistency of insar and gnss data for retrieving 3d displacement rapid changes the example of the 2015 piton de la fournaise eruptions abstract insar and gnss are now the best and most developed techniques in the earth sciences to track deformation especially in volcanology in this study we assess the reliability and consistency of these two techniques for measuring 3 d ground displacements and not only the displacement in the direction of the insar line of sight on volcanoes during rapid changes the use of a large amount of satellite data x c l band as well as right and left looking acquisitions made it possible to retrieve the 3 d displacement components with an unprecedented accuracy we carry out this evaluation on the piton de la fournaise volcano where four eruptions occurred in 2015 the comparison between gnss and insar allows us i to describe the deformation pattern associated with these eruptions ii to quantify the discrepancies between insar and gnss and iii to discuss the limits and the complementarities of insar and gnss the ground deformation patterns associated with the four eruptions of piton de la fournaise in 2015 are typical of this volcano with decimeter ground displacements asymmetrically distributed along the dike path evidencing a preferential eastward motion particularly visible thanks to the broad spatial coverage of insar except for the ns component insar and gnss data are in overall agreement with most of the gnss insar residuals

measuring ground displacements from sar amplitude images application to the landers earthquake ers sar amplitude images are utilized to map ground displacements from a sub pixel correlation method it yields a ground two dimensional displacement field with independent measurements about every 128m in azimuth and 250m in range the accuracy depends on the characteristics of the images for the landers test case the 1 uncertainty is 0 8m in range and 0 4m in azimuth we show that this measurement provides a map of major surface fault ruptures accurate to better than 1km and information on coseismic deformation comparable to the 92 gps measurements available although less accurate this technique is more robust than sar interferometry and provides complementary information since interferograms are only sensitive to the displacement in range

coseismic and postseismic slip of the 2004 parkfield earthquake from space geodetic data we invert interferometric synthetic aperture radar insar data jointly with campaign and continuous global positioning system gps data for slip in the coseismic and postseismic periods of the 2004 parkfield earthquake the insar dataset consists of eight interferograms from data collected by the envisat and radarsat satellites spanning the time of the earthquake and variable amounts of the postseismic period the two datasets complement each other with the insar providing dense sampling of motion in the range direction of the satellite and the gps providing more sparse but three dimensional measurements of ground motion the model assumes exponential decay of the postseismic slip with a decay time constant of 0 087 years determined from time series modeling of continuous gps and creepmeter data we find a geodetic moment magnitude of m 6 2 for a 1 day coseismic model and m w 6 1 for the entire postseismic period the coseismic rupture occurred mainly in two slip asperities one near the hypocenter and the other 15 20 km north postseismic slip occurred on the shallow portions of the fault and near the rupture areas of two m 5 0 aftershocks a comparison of the geodetic slip models with seismic moment estimates suggests that the coseismic moment release of the parkfield earthquake is as little as 25 of the total this underlines the importance of aseismic slip in the slip budget for the parkfield segment online material complete data tables and supplemental tables

estimating source parameters from deformation data with an application to the march 1997 earthquake swarm off the izu peninsula japan we have applied two monte carlo optimization techniques simulated annealing and random cost to the inversion of deformation data for fault and magma chamber geometry these techniques involve an element of randomness that permits them to escape local minima and ultimately converge to the global minimum of misfit space we have tested the monte carlo algorithms on two synthetic data sets we have also compared them to one another in terms of their efficiency and reliability we have applied the bootstrap method to estimate confidence intervals for the source parameters including the correlations inherent in the data additionally we present methods that use the information from the bootstrapping procedure to visualize the correlations between the different model parameters we have applied these techniques to gps tilt and leveling data from the march 1997 earthquake swarm off of the izu peninsula japan using the two monte carlo algorithms we have inferred two sources a dike and a fault that fit the deformation data and the patterns of seismicity and that are consistent with the regional stress field

the 2008 may 29 earthquake doublet in sw iceland summary on 2008 may 29 an earthquake doublet shook the southwestern part of iceland the first main shock originated beneath mt ingolfsfjall located near the western margin of the south iceland seismic zone sisz approximately 40 km east of the capital reykjavik immediate aftershock activity was recorded by the sil seismic network operated by the icelandic meteorological office imo with both n s and e w structures illuminated over a broad area a continuous gps cgps network also operated by the imo recorded coseismic offsets with up to 200 mm of horizontal motion at the closest stations we estimate the coseismic surface deformation observed by campaign and continuous gps and satellite radar data insar we invert the geodetic data to find the optimal geometry location and slip on the main faults accounting for variation in the elastic parameters of the crust with depth our models indicate that most of the slip occurred on two n s structures spaced 5 km apart from a joint inversion of gps and insar data for variable slip models we find that most of the slip for the first ingolfsfjall event was concentrated at 2 4 km depth with a maximum of 1 9 m whereas the slip on the second kross fault was located deeper at 3 6 km depth with up to 1 4 m of motion the models give similar geodetic moments for the two main events equivalent to a moment magnitude of mw5 8 and mw5 9 for the first and second event respectively our estimated composite moment therefore equals a mw6 1 for the doublet smaller than the mw6 3 estimated from teleseismic data e g neic and harvard the geodetic data support rupture on two main faults and analysis of high rate 1 hz cgps data suggests that slip on the second fault initiated within 3 s of the first main shock static coulomb failure stress calculations indicate that the first event caused a stress increase in the area of the main asperity i e at the location of the largest slip patch on the second fault however we cannot rule out dynamic stress triggering due to the short time between the two main events the 2008 may 29 earthquake doublet appears to be a continuation of the earthquake sequence that started in 2000 june when two mw6 5 events struck the eastern and central part of the south iceland seismic zone in the span of 81 hr the 2000 june 2008 may sequence has released about half of the moment accumulated by plate motion since the previous earthquake sequence in 1896 1912 therefore continued earthquake activity with moderate size events rupturing n s faults in the sisz in the coming decades is likely

coseismic deformation of the 2001 mw 7 8 kokoxili earthquake in tibet measured by synthetic aperture radar interferometry the 14 november 2001 m w 7 8 kokoxili earthquake ruptured more than 400 km of the westernmost stretch of the left lateral kunlun fault in northern tibet interferometric synthetic aperture radar data from descending orbits along four adjacent tracks covering almost the entire rupture and 1 m pixel ikonos satellite images are used to map the rupture geometry and the surface displacements produced by the event interferograms are then inverted to solve for coseismic slip on the fault at depth the radar data show that the rupture connected the heituo fault where the earthquake initiated to the main kunlun fault cutting across a pull apart trough in between the two strike slip faults the fault model includes two vertical sections extending to a depth of 20 km and discretized into 5 km 5 km patches using a nonnegative least squares method that includes an appropriate degree of smoothing we solve for the left lateral slip on each fault patch our solution shows that the largest slip occurred at depths between 0 and 5 km reaching 8 m in two areas 200 and 250 km east of the earthquake epicenter significant slip took place below 10 km at both ends of the rupture slip appears to have been highly variable along the fault defining six sections of major moment release these sections correspond to six subsegments of the kunlun fault system defined from the surface morphology of the fault this suggests that fault geometry exerted a predominant influence on controlling the rupture propagation

a spatial random field model to characterize complexity in earthquake slip 1 finite fault source inversions reveal the spatial complexity of earthquake slip over the fault plane we develop a stochastic characterization of earthquake slip complexity based on published finite source rupture models in which we model the distribution of slip as a spatial random field the model most consistent with the data follows a von karman autocorrelation function acf for which the correlation lengths a increase with source dimension for earthquakes with large fault aspect ratios we observe substantial differences of the correlation length in the along strike a x and downdip a z directions increasing correlation length with increasing magnitude can be understood using concepts of dynamic rupture propagation the power spectrum of the slip distribution can also be well described with a power law decay i e a fractal distribution in which the fractal dimension d remains scale invariant with a median value d 2 29 0 23 while the comer wave number k c which is inversely proportional to source size decreases with earthquake magnitude accounting for larger slip patches for large magnitude events our stochastic slip model can be used to generate realizations of scenario earthquakes for near source ground motion simulations

source model for the 1997 zirkuh earthquake mw 7 2 in iran derived from jers and ers insar observations summary we present the first detailed source model of the 1997 m7 2 zirkuh earthquake that ruptured the entire abiz fault in east iran producing a 125 km long bended and segmented fault trace using sar data from the ers and jers 1 satellites we first determined a multisegment fault model for this predominately strike slip earthquake by estimating fault segment dip slip and rake values using an evolutionary optimization algorithm we then inverted the insar data for variable slip and rake in more detail along the multisegment fault plane we complement our optimization with importance sampling of the model parameter space to ensure that the derived optimum model has a high likelihood to detect correlations or trade offs between model parameters and to image the model resolution our results are in an agreement with field observations showing that this predominantly strike slip earthquake had a clear change in style of faulting along its rupture in the north we find that thrust faulting on a westerly dipping fault is accompanied with the strike slip that changes to thrust faulting on an eastward dipping fault plane in the south the centre part of the fault is vertical and has almost pure dextral strike slip the heterogeneous fault slip distribution shows two regions of low slip near significant fault step overs of the abiz fault and therefore these fault complexities appear to reduce the fault slip furthermore shallow fault slip is generally reduced with respect to slip at depth this shallow slip deficit varies along the zirkuh fault from a small deficit in the north to a much larger deficit along the central part of the fault a variation that is possibly related to different interseismic repose times

the may 2005 eruption of fernandina volcano galapagos the first circumferential dike intrusion observed by gps and insar the may 2005 eruption of fernandina volcano galapagos occurred along circumferential fissures parallel to the caldera rim and fed lava flows down the steep southwestern slope of the volcano for several weeks this was the first circumferential dike intrusion ever observed by both insar and gps measurements and thus provides an opportunity to determine the subsurface geometry of these enigmatic structures that are common on galapagos volcanoes but are rare elsewhere pre and post eruption ground deformation between 2002 and 2006 can be modeled by the inflation of two separate magma reservoirs beneath the caldera a shallow sill at 1 km depth and a deeper point source at 5 km depth and we infer that this system also existed at the time of the 2005 eruption the co eruption deformation is dominated by uplift near the 2005 eruptive fissures superimposed on a broad subsidence centered on the caldera modeling of the co eruption deformation was performed by including various combinations of planar dislocations to simulate the 2005 circumferential dike intrusion we found that a single planar dike could not match both the insar and gps data our best fit model includes three planar dikes connected along hinge lines to simulate a curved concave shell that is steeply dipping 45 60 toward the caldera at the surface and more gently dipping 12 14 at depth where it connects to the horizontal sub caldera sill the shallow sill is underlain by the deep point source the geometry of this modeled magmatic system is consistent with the petrology of fernandina lavas which suggest that circumferential eruptions tap the shallowest parts of the system whereas radial eruptions are fed from deeper levels the recent history of eruptions at fernandina is also consistent with the idea that circumferential and radial intrusions are sometimes in a stress feedback relationship and alternate in time with one another

evidence of instantaneous dynamic triggering during the seismic sequence of year 2000 in south iceland 1 we analyze the coseismic stress perturbation during the 17 june 2000 south iceland seismic sequence the main shock ms 6 6 was followed by three large events within a few tens of seconds 8 26 and 30 s located within 80 km the aim of this paper is to investigate short term fault interaction and instantaneous triggering this happens when a fault perturbed by a stress change fails before the end of the transient stress perturbation we compute the shear normal and coulomb stress changes as functions of time in a stratified elastic half space by using discrete wave number and reflectivity methods we calculate dynamic stresses caused by the main shock at the hypocenters of these three subsequent events our numerical results show that the onset of the last two events is slightly delayed with respect to the arrival time of the second positive peak of coulomb stress variation while the first event occurred after the first positive stress peak we have also analyzed the response of a spring slider system representing a fault governed by a rate and state dependent friction law perturbed by shear and normal stress variations caused by the main shock the fault response to the computed stress perturbations is always clock advanced we have found suitable constitutive parameters of the modeled fault that allow the instantaneous dynamic triggering of these three earthquakes if the initial sliding velocity is comparable with the tectonic loading velocity we obtained failure times close to the observed origin times for low values of the initial effective normal stress

source model for the mw 6 7 23 october 2002 nenana mountain earthquake alaska from insar 1 the 23 october 2002 nenana mountain earthquake mw 6 7 occurred on the denali fault alaska to the west of the mw 7 9 denali earthquake that ruptured the same fault 11 days later we used 6 interferograms constructed using radar images from the canadian radarsat 1 and european ers 2 satellites to determine the coseismic surface deformation and a source model data were acquired on ascending and descending satellite passes with incidence angles between 23 and 45 degrees and time intervals of 72 days or less modeling the event as dislocations in an elastic half space suggests that there was nearly 0 9 m of right lateral strike slip motion at depth on a near vertical fault and that the maximum slip in the top 4 km of crust was less than 0 2 m the nenana mountain earthquake increased the coulomb stress at the future hypocenter of the 3 november 2002 denali earthquake by 30 60 kpa

earthquakes stress and strain along an obliquely divergent plate boundary reykjanes peninsula southwest iceland earthquakes stress and strain along an obliquely divergent plate boundary the reykjanes peninsula southwest iceland

relation between continental strike slip earthquake segmentation and thickness of the crust 1 high resolution maps of large continental strike slip earthquake surface ruptures show that they are formed of fault segments these segments are bounded by fault bends step overs or combinations of the two the lowest limit in size for such segments may not be relevant in the understanding of earthquake mechanics as it pertains to the granular properties of fault zones the maximum limit in segment length however is important as it is directly relates to the maximum extent of seismic rupture to measure the length of the segments a new quantitative method based on piecewise linear fitting is developed and is used to automatically retrieve segments from earthquake rupture maps next this approach is tested against a set of ten continental strike slip earthquake ruptures derived from similar high quality maps the test suggests that segments have a maximum length of 18 km independent of regional tectonic setting slip inversions for earthquakes based on seismological and or geodetic data most often are not unique and can show some variability even for one particular event some basic characteristics however such as total moment release or general source geometry seem to persist that are relevant to earthquake mechanics measurements of the maximum horizontal extent of individual slip patches derived from seismic source inversion for strike slip ruptures show that their strike dimension does not increase infinitely with magnitude but instead reaches a maximum value of 25 km these two independent lines of observations complemented by earlier data and analog experiments suggest that it is the thickness of the seismogenic crust that controls the structural scaling of the length of seismic segments and that it is independent of the ultimate size of individual earthquakes

an active ring fault detected at tendurek volcano by using insar 1 although ring faults are present at many ancient deeply eroded volcanoes they have been detected at only very few modern volcanic centers at the so far little studied tendurek volcano in eastern turkey we generated an ascending and a descending insar time series of its surface displacement field for the period from 2003 to 2010 we detected a large 105 km2 region that underwent subsidence at the rate of 1 cm yr during this period source modeling results show that the observed signal fits best to simulations of a near horizontal contracting sill located at around 4 5 km below the volcano summit intriguingly the residual displacement velocity field contains a steep gradient that systematically follows a system of arcuate fractures visible on the volcano s midflanks rapideye satellite optical images show that this fracture system has deflected holocene lava flows thus indicating its presence for at least several millennia we interpret the arcuate fracture system as the surface expression of an inherited ring fault that has been slowly reactivated during the detected recent subsidence these results show that volcano ring faults may not only slip rapidly during eruptive or intrusive phases but also slowly during dormant phases

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

fault slip in the 1997 manyi tibet earthquake from linear elastic modelling of insar displacements summary the mw 7 6 1997 manyi earthquake occurred in an area of central northern tibet where sparse vegetation coverage and a lack of human habitation provide excellent conditions for interferometric synthetic aperture radar insar studies we use coseismic pairs of radar images acquired by the esa ers 2 satellite to construct interferograms of the surface displacement field due to the earthquake the location and extent of the coseismic fault rupture are mapped using a combination of optical satellite imagery high resolution digital topography interferometric correlation and azimuth offset measurements in so doing we are able to relate prominent geomorphic features in the fault zone to bends in the fault using elastic dislocation models consistent with this mapped fault trace we then test a range of fault geometries and slip conditions to find the combination which best explains the insar displacements our favoured model contains a reversal in fault dip approximately halfway along its length occurring at the location of a restraining bend slip on this model fault is heterogeneous with two areas of peak slip of 7 m or greater and components of dip slip displacement which vary significantly along strike the success of this model in fitting the data implies that an observed asymmetry in the coseismic interferograms can be explained in terms of the local fault geometry rather than by using non linear elastic rheologies as suggested by earlier authors

some thoughts on the use of insar data to constrain models of surface deformation noise structure and data downsampling repeat pass interferometric synthetic aperture radar insar provides spatially dense maps of surface deformation with potentially tens of millions of data points here we estimate the actual covariance structure of noise in insar data we compare the results for several independent interferograms with a large ensemble of gps observations of tropospheric delay and discuss how the common approaches used during processing of insar data affects the inferred covariance structure motivated by computational concerns associated with numerical modeling of deformation sources we then combine the data covariance information with the inherent resolution of an assumed source model to develop an efficient algorithm for spatially variable data resampling or averaging we illustrate these technical developments with two earthquake scenarios at different ends of the earthquake magnitude spectrum for the larger events our goal is to invert for the coseismic fault slip distribution for smaller events we infer the hypocenter location and moment we compare the results of inversions using several different resampling algorithms and we assess the importance of using the full noise covariance matrix

synthetic seismogram modelling of the oceanic pn phase the seismic oceanic pn phase is characterized by low spatial attenuation a high frequency wavetrain of extremely long duration and an onset velocity near 8 0 km s 1 in an effort to explain these properties models have been proposed for the mode of propagation of this phase which include energy entrapment within a low velocity channel1 2 propagation within an extremely low attenuation lithosphere waveguide3 4 and forward scattering from local heterogeneity within the oceanic crust5 6 through synthetic seismogram modelling we have generated realistic oceanic pn phases for an oceanic lithosph re model that did not contain any of these intrinsic properties the synthetic pn phase can be explained rather simply as a set of refractions from the lower lithosphre with subsequent reverberations within the oceanic water column and sediment layer many of the spectral properties associated with layer reverberation observed in the synthetic pn phase are revealed in data collected in the south west pacific complicated oceanic lithosphere models are not required to explain the gross characteristics of pn propagation

the 2015 mw7 2 sarez strike slip earthquake in the pamir interior response to the underthrusting of india s western promontory the pamir orogen central asia is the result of the ongoing northward advance of the indian continent causing shortening inside asia geodetic and seismic data place the most intense deformation along the northern rim of the pamir but the recent 7 december 2015 mw7 2 sarez earthquake occurred in the pamir s interior we present a distributed slip model of this earthquake using coseismic geodetic data and postseismic field observations the earthquake ruptured an 80 km long subvertical sinistral fault consisting of three right stepping segments from the surface to 30 km depth with a maximum slip of three meters in the upper 10 km of the crust the coseismic slip model agrees well with en echelon secondary surface breaks that are partly influenced by liquefaction induced mass movements these structures reveal up to 2 m of sinistral offset along the northern low offset segment of modeled rupture the 2015 event initiated close to the presumed epicenter of the 1911 mw 7 3 lake sarez earthquake which had a similar strike slip mechanism these earthquakes highlight the importance of ne trending sinistral faults in the active tectonics of the pamir strike slip deformation accommodates shear between the rapidly northward moving eastern pamir and the tajik basin in the west and is part of the westward lateral extrusion of thickened pamir plateau crust into the tajik basin the sarez karakul fault system and the two large sarez earthquakes likely are crustal expressions of the underthrusting of the northwestern leading edge of the indian mantle lithosphere beneath the pamir

joint inversion of insar gps teleseismic and strong motion data for the spatial and temporal distribution of earthquake slip application to the 1999 izmit mainshock the space time distribution of slip of the 17 august 1999 izmit earthquake is investigated by inverting synthetic aperture radar sar interferometry and global positioning system gps data together with teleseismic broadband and near field strong motion records surface offsets are used as an added constraint special emphasis is given to analysis of the resolution of the different data sets we use a four segment finite fault model and a nonlinear inversion scheme allowing slip to vary in amplitude direction and duration as well as variable rupture velocity from the inversion of synthetic data we find that the best spatial resolution can be expected in the upper half of the fault model above 12 km where coverage of the interferometric sar data is good western half of the rupture and near the gps and strong motion stations teleseismic data are found to have a lower resolution that is more evenly distributed over the fault model the joint inversion of all the data sets has an increased resolving power compared with the separate inversions and gives a more robust description of the space and time distribution of slip our study shows the importance of resolution tests in evaluating the reliability of earthquake kinematic models and it confirms that an excellent fit of a single kind of data does not necessarily imply a good retrieval of the kinematic properties of an earthquake the izmit rupture which is almost pure right lateral strike slip faulting is dominated by the bilateral breaking of a central asperity located between 29 7 e about 10 km west of the city of golcuk and 30 4 e eastern margin of sapanka lake with slip reaching 6 8 m in the depth range 6 12 km the western termination of the rupture is found near the city of yalova but large slip ends around 29 7 e about 10 km east of hersek delta a second area of large slip is required by all the data sets further east toward the city of duzce between 30 7 e and 31 1 e karadere and duzce faults this eastern slip zone which is separated from the main central asperity by an area of greatly reduced slip is less well constrained by the data however a strong motion station near the city of duzce helps to locate a high slip patch near 31 1 e in the depth range 6 12 km the total seismic moment resulting from the joint inversion is 2 4 1027 dyne cm most of the energy release occurred in a short time less than 15 sec corresponding to the bilateral breaking of the central asperity rupture propagation is relatively uniform and fast toward the west with a rupture velocity close to 3 5 km sec propagation of large slip toward the east is initially slower but it accelerates during a short time interval about 10 sec after rupture nucleation eastward progression then slows down to less than 2 km sec after 15 sec and rupture almost vanishes in amplitude ca 20 sec after initiation rupture propagation then proceeds on the easternmost karadere and duzce fault segments east of 30 7 e from 22 to ca 50 sec supershear rupture propagation is not required for modeling the waveforms considered in this study the hypocenter of the duzce earthquake which occurred 3 months later 12 november 1999 m w 7 2 is located in the immediate vicinity of the easternmost slip patch of the izmit earthquake manuscript received 28 july 2000

finding realistic dike models from interferometric synthetic aperture radar data the february 2000 eruption at piton de la fournaise dike intrusions often cause complex ground displacements that are not sufciently explained by simple analytical models we develop a method to nd complex and realistic dike geometries and overpressures from interferometric synthetic aperture radar insar data this method is based on a combination of a boundary element method with realistic topography and a neighbourhood algorithm inversion dike model geometry is roughly a quadrangle with its top reaching the ground the inversion has two stages search and appraisal the appraisal stage involves calculations of model marginal probability density functions using mist val ues calculated during the search stage the mist function takes into account the variance and correlation of data noise synthetic tests show that a model is successfully retrieved within predicted narrow condence intervals we apply the method on insar data of the february 2000 ank eruption at piton de la fournaise and get a trapezoid dike dipping seaward 61 0 n 67 3 with its bottom passing 800n1000 m beneath the summit a model with a basal slip plane does not better explain observed asymmetric displacements and thus this asymmetry is solely attributed to the dipping dike the dike lies above a narrow band of pre eruption seis micity suggesting that lateral magma propagation occurred neglecting topography results in poor modeling at depth and in overestimations of overpressure or opening height both about 30 and volume about 20

lithospheric rheology constrained from twenty five years of postseismic deformation following the 1989 mw 6 9 loma prieta earthquake abstract the october 17 1989 m w 6 9 loma prieta earthquake provides the first opportunity of probing the crustal and upper mantle rheology in the san francisco bay area since the 1906 m w 7 9 san francisco earthquake here we use geodetic observations including gps and insar to characterize the loma prieta earthquake postseismic displacements from 1989 to 2013 pre earthquake deformation rates are constrained by nearly 20 yr of usgs trilateration measurements and removed from the postseismic measurements prior to the analysis we observe gps horizontal displacements at mean rates of 1 4 mm yr toward loma prieta mountain until 2000 and 2 mm yr surface subsidence of the northern santa cruz mountains between 1992 and 2002 shown by insar which is not associated with the seasonal and longer term hydrological deformation in the adjoining santa clara valley previous work indicates afterslip dominated in the early 1989 1994 postseismic period so we focus on modeling the postseismic viscoelastic relaxation constrained by the geodetic observations after 1994 the best fitting model shows an elastic 19 km thick upper crust above an 11 km thick viscoelastic lower crust with viscosity of 6 10 18 pa s underlain by a viscous upper mantle with viscosity between 3 10 18 and 2 10 19 pa s the millimeter scale postseismic deformation does not resolve the viscosity in the different layers very well and the lower crustal relaxation may be localized in a narrow shear zone however the inferred lithospheric rheology is consistent with previous estimates based on post 1906 san francisco earthquake measurements along the san andreas fault system the viscoelastic relaxation may also contribute to the enduring increase of aseismic slip and repeating earthquake activity on the san andreas fault near san juan bautista which continued for at least a decade after the loma prieta event

triggered fault slip on june 17 2000 on the reykjanes peninsula sw iceland captured by radar interferometry 1 dynamically triggered seismicity followed shortly after a ms 6 6 earthquake in iceland on june 17 2000 smaller earthquakes occurred on the reykjanes peninsula up to 100 km from the mainshock rupture using interferometric analysis of synthetic aperture radar images insar we measure crustal deformation associated with three triggered deformation events the largest of these occurred at lake kleifarvatn 85 km west of the mainshock epicenter modeling of the insar data reveals strikeslip on a north striking fault with a geodetic moment of 6 2 1017 nm equivalent to magnitude mw 5 8 earthquake a seismological estimate of the moment is not yet available because the seismic signature of this event is partly hidden by the mainshock waveform the paucity of aftershocks on the triggered rupture plane suggests some aseismic slip there compatible with a thin seismogenic crust high heat flow hydrothermal alteration and the presence of fluids in the area

the relationship between seismic and aseismic slip on the philippine fault on leyte island bayesian modeling of fault slip and geothermal subsidence delineating seismic and aseismic slip on faults allows the exploration of the complex relationship between these different modes of slip further quantifying them helps in the assessment of seismogenic potential we present a distributed slip model of the rate of aseismic slip along the leyte island section of the philippine fault and make comparisons with the extent of seismic slip from the latest significant earthquakes in july 2017 we derived both coseismic and aseismic slip distributions from kinematic inversions of synthetic aperture radar interferometric insar observations using a probabilistic bayesian framework velocity maps from stacking and time series analysis of alos interferograms spanning 4 years 2007 2011 show a step change in ground deformation right on the fault inverting for slip at depth reveals along strike variations of aseismic slip rate over 100 km aseismic slip on the surface reaches rates of more than 3 cm yr equivalent to the long term slip rate 3 3 0 2 cm yr over the same period a 20 km segment in tongonan appears to be locked this segment ruptured in mw 6 5 and mw 5 8 earthquakes on 6 and 10 july 2017 respectively as constrained by sentinel 1 and alos 2 insar data seismic slip appears to be restricted within the tongonan segment with up to 152 21 cm of left lateral displacement the slip budget and complementarity between the extents of interseismic and coseismic slip suggest that a seismogenic asperity exists in tongonan the presence of active hydrothermal systems and rate strengthening materials provide physical conditions that can promote aseismic slip

3d coseismic deformations and source parameters of the 2010 yushu earthquake china inferred from dinsar and multiple aperture insar measurements abstract the coseismic deformation field related to the 2010 mw6 9 yushu earthquake qinghai china has been investigated by previous studies using the satellite differential interferometric synthetic aperture radar dinsar method however one of the limiting factors in the conventional dinsar is that it can measure only one dimensional 1d ground motion along the radar line of sight los direction thus resulting in anamorphic coseismic displacements and biased source parameters in this paper the three dimensional 3d deformation maps for this earthquake were reconstructed over an area of about 100 70 km2 for the first time by a combined use of the dinsar method for detecting los motion and the multiple aperture interferometry mai method for detecting along track at motion the fault slip map for this earthquake was generated using the 3d deformation maps based on the fault traces on the fault slip map we constructed a fault model with five segments and preformed a two step inversion using the 3d deformation data as the constraint our results show that the maximum coseismic displacements in up down north south and east west directions are 40 4 113 8 and 65 7 cm respectively and the peak to peak slip offset between the southern and northern fault wall is 1 82 m our model reveals a shallow dislocation on a nw se trending fault extending about 74 km along which the four fault segments are nearly vertical 84 88 and the one fault segment dips 66 2 to the southwest the estimated seismic moment is 2 43 1019 nm mw6 92 which is close to the solution provided by the global centroid moment tensor gcmt project the slip distribution derived for each fault patch shows that the slip occurrence extends down to 12 km beneath the ground surface and a peak slip of 2 23 m appears at the depth of about 5 km right near the epicenter comparison with the results derived from the seismic waves field investigation gps and conventional dinsar observations indicates that the source parameters of the yushu earthquake can be improved due to the combined use of dinsar and mai measurements

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

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

stress interaction between magma accumulation and trapdoor faulting on sierra negra volcano galapagos abstract understanding the state of stress within volcanoes and how it changes with active geophysical processes is important to assess when and where magma may propagate to the surface and initiate an eruption observations of volcanic deformation help to constrain parameters of models that can be used to describe these processes and to calculate the resulting stress changes within volcanoes here i use geodetic observations to constrain elastic dislocation models of magma accumulation and faulting at sierra negra volcano galapagos in the years before the october 2005 eruption which was the first eruption at sierra negra since 1979 both insar and gps data document a remarkable story of 5 m pre eruption uplift during 1992 2005 which was accompanied by at least three trapdoor faulting events on an intra caldera fault system in january 1998 april 2005 and just before the eruption in october 2005 the pattern of uplift observed in the insar data from different time periods during 1992 2005 is consistent with filling and pressurization of a 2 2 km deep sill under the caldera modeling results for the trapdoor faulting in april 2005 on the other hand indicate that slip occurred on a thrust fault that dips steeply 71 in towards the center of the caldera and extends from the surface down to the sill at 2 2 km depth independently the calculated stress changes caused by the inflating sill show that the coulomb failure stress change cfs at the fault s location is maximized on a 72 dipping thrust fault agreeing almost exactly with the deformation modeling result and implying that the inflation triggered the faulting the calculations also show that the cfs for optimally oriented faults any strike and dip is significantly larger in the southern part of the caldera where the faulting took place than at any other location the trapdoor faulting in turn relieved the pressure within the sill but caused compression to the south of the faults this suggests that while the faulting provides a mechanism for the sill to thicken and postpone eruptions it also prevents the sill from growing to the south

surface effects of triggered fault slip on reykjanes peninsula sw iceland three large earthquakes mw 4 5 were triggered within 5 min 85 km west of a mw 6 5 earthquake in the south iceland seismic zone sisz we report on surface effects of these triggered earthquakes which include fresh rupture widespread rockfall disrupted rockslides and block slides field data confirm that the earthquakes occurred along n striking right lateral strike slip faults field data also support the conclusion from modeling of insar data that deformation from the second triggered event was more significant than for the other two a major hydrological effect was the draining of water through an open fissure on a lake bed lowering the lake level by greater than 4 m field relationships suggest that a component of aseismic slip could have been facilitated by water draining into the fault zone d 2003 elsevier science b v all rights reserved