shallow fault zone dilatancy recovery after the 2003 bam earthquake in iran earthquakes radiate from slip on discrete faults but also commonly involve distributed deformation within a broader fault zone especially near the surface variations in rock strain during an earthquake are caused by heterogeneity in the elastic stress before the earthquake by variable material properties and geometry of the fault zones and by dynamic processes during the rupture stress changes due to the earthquake slip both dynamic and static have long been thought to cause dilatancy in the fault zone that recovers after the earthquake decreases in the velocity of seismic waves passing through the fault zone due to coseismic dilatancy have been observed followed by postseismic seismic velocity increases during healing dilatancy and its recovery have not previously been observed geodetically here we use interferometric analysis of synthetic aperture radar images to measure postseismic surface deformation after the 2003 bam iran earthquake and show reversal of coseismic dilatancy in the shallow fault zone that causes subsidence of the surface this compaction of the fault zone is directly above the patch of greatest coseismic slip at depth the dilatancy and compaction probably reflects distributed shear and damage to the material during the earthquake that heals afterwards coseismic and postseismic deformation spread through a fault zone volume may resolve the paradox of shallow slip deficits for some strike slip fault ruptures

finite faults and inverse theory with applications to the 1979 imperial valley earthquake abstract using a representation theorem from elastodynamics subsurface slip on a known fault is formulated as the solution to an inverse problem in which recorded surface ground motion is the data two methods of solution are presented the least squares method which minimizes the squared differences between theory and data and the constrained least squares method which simultaneously maintains a set of linear inequalities instabilities in the solution are effectively eliminated in both methods and the sensitivity of the solution to small changes in the data is quantitatively stated the inversion methodology is applied to 77 components of near field ground acceleration recorded during the 15 october 1979 imperial valley earthquake the faulting is constrained to propagate bilaterally away from the epicenter at an average velocity of 90 per cent of the shear wave speed on a vertical fault plane extending from the surface to 10 km depth inequality constraints are used to keep the faulting sequence physically reasonable by maintaining right lateral motion and positive slip velocity the preferred solution is stable and provides a good fit to the data it is also realistic and consistent with observed surface offsets and independent estimates of seismic moment

combination of precise leveling and insar data to constrain source parameters of the mw 6 5 26 december 2003 bam earthquake we used new precise leveling data acquired 40 days after the bam earthquake in combination with radar interferometry observations from both ascending and descending orbits to investigate static deformation associated with the 2003 bam earthquake we invert this geodetic data set to gain insight into the fault geometry and slip distribution of the rupture the best fitting dislocation model is a steeply east dipping right lateral strike slip fault that has a size of 11 by 8 km and strikes n2 w we find that such smooth geometry fits available geodetic data better than previously proposed models for this earthquake our distributed slip model indicates a maximum strike slip of 3 m occurring about 3 to 5 km deep the slip magnitude and depth of faulting taper to the north where the fault approaches the bam city inclusion of crustal layering increases the amount of maximum slip inferred at depth by about 4

source model for the mw 6 1 31 march 2006 chalan chulan earthquake iran from insar we use insar to measure deformation and kinematics of the mw 4 9 borujerd 2005 05 03 and mw 6 1 chalan chulan 2006 03 31 earthquakes that occurred in the zagros fold and thrust belt the focal mechanism of the 2006 event is consistent with right lateral strike slip motion and the event ruptured the dorud borujerd segment of the main recent fault an envisat interferogram spanning the 2006 event shows peak ground deformation of 9 cm in the satellite line of sight along a 10 km long fault portion the interferogram spanning the 2005 earthquake is rather related to atmospheric artefact than to ground deformation dislocation models of the 2006 chalan chulan event indicate dextral slip amounting to a maximum of 90 cm at a depth of 4 km the predicted vertical displacements are in good agreement with differential levelling data the 2006 event filled only a small part of the seismic gap located between large m 7 events that occurred in 1909 and 1957

contribution of radar interferometry to a two step inversion of the kinematic process of the 1992 landers earthquake we study the rupture process of the 1992 landers earthquake to limit the trade off between slip amplitude and rupture time that affects solutions using only seismological data we adopt a two step approach we first constrain the slip distribution and its uncertainty by independent geodetic data to recover in the second step the temporal details of the rupture propagation the first step consists of an inversion of interferometric data and global positioning system measurements both independently and together to constrain slip distribution on a three segment fault model along both strike and dip direction we use a genetic algorithm to test the uniqueness of the solution and a least squares formulation to find the model which best fits the data we conclude from the results of these geodetic inversions that interferometric data are rich enough to access the slip distribution in the case of the landers earthquake since the surface deformations are more sensitive to shallow slip in our configuration the slip amplitude is better resolved near the surface than at depth the resulting slip distribution is in agreement with geological observations at the surface and confirms the heterogeneous nature of the landers earthquake most of the slip occurs at shallow depths on the homestead valley fault second segment with a maximum value of around 7 m another high slip zone is observed on the johnson valley fault first segment at 8 km depth in the second step we invert strong motion data with the a priori final slip amplitude and its uncertainty deduced from geodetic data to constrain the time history of the rupture process this second step emphasizes a strong variation of the temporal development of the earthquake fast rupture front velocities appear within high slip zones and the rupture slows when it encounters a resistance along the fault on average the rupture front propagates with velocities close to the s wave velocity and terminates about 20 s after initiation the large variations in both slip amplitude and rupture velocity suggest that the rupture process is better described by successively breaking asperities than by a pulse propagating with constant velocity

assessment of the palaeoclimate during 3 0 2 6 ma registered by transition of red clay to loess palaeosol sequence in central north china abstract a continuously accumulated section the yanyu section of red clay and loess palaeosol sequence from the southernmost chinese loess plateau was selected for this study of palaeoclimate of the late pliocene to early pleistocene period termination of the red clay accumulation and onset of loess deposition was coincident with the beginning of extensive northern hemisphere glaciation at 2 6 ma field observations and compositional analyses suggest an aeolian origin for the red clay much like the processes experienced by the loess palaeosol sequence pedogenic analysis indicates that the late pliocene red clay first experienced complete decalcification and illuviation mechanical translocation of clays in all horizons including the present carbonate precipitation zones but other chemical alterations have been rather weak and even weaker than experienced by the overlying loess derived palaeosols in great contrast to the pleistocene climate characterised by frequent and large amplitude fluctuations between cold dry and warm wet a relatively steady warm dry climate condition is implied for the late pliocene dustfall rate assessment indicates a much lower accumulation rate during the late pliocene than in the early pleistocene in agreement with a notable systematic coarsening from the red clay to the overlying loess and palaeosols together these features suggest that the dust transport agent the northwesterly winds were weaker over the late pliocene the transition from red clay to loess possibly marked a significant and rapid shift in the climatic system in east asia

deformation due to the 17 august 1999 izmit turkey earthquake measured from spot images the geometry of the ruptured areas and the coseismic slip distribution data are key to highlighting the behavior of seismic faults this information is generally retrieved from field investigations and geodetic measurements or synthetic aperture radar sar interferometry here we show that spot images can also be used to accurately map the fault zone and to determine the slip distribution by subpixel correlation of images acquired before and after an earthquake the measured slip includes the contribution of possible distributed shear that might not be clearly expressed in surface ruptures and smoothes out possible along strike variability due to near surface fault complexities we apply the technique to the m s 7 4 1999 izmit earthquake our results reveal a 100 m wide and very linear fault zone that can be traced for 70 km from golcuk to akyazi along which supershear rupture has been inferred the obtained slip distribution compares well with the field measurements and is consistent with ground deformation measured at some distance from the fault zone using sar images very little deformation was accommodated off the main fault plane maximum slip is observed near sapanca lake at a small fault jog that has probably influenced rupture propagation

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

coseismic deformation from earthquake faulting on a layered spherical earth summary a method for calculating the static displacement field following earthquake faulting in a layered spherical earth is presented at shallow levels the earth s layering is characterized by sharp jumps in bulk and shear moduli at the conrad discontinuity and the moho and is therefore important to consider when evaluating crustal deformation the solution to the equations of static equilibrium is represented as a superposition of spheroidal and toroidal components that each depend on spherical harmonic degree and the moment tensor a method that has recently been applied to the problem of wave propagation on a layered spherical earth is here applied to the static deformation field by representing the point source in terms of discontinuities in the displacement stress vector the green s function for a particular source geometry is derived directly numerical tests are presented to verify the accuracy of the method and to illustrate the effects of sphericity and layering on the calculated deformation fields the effect of sphericity is generally less than about 2 per cent of maximum deformation within 100 km of an earthquake source at crustal depths comparisons between the deformation calculated on a spherical homogeneous earth and spherical layered earth show that up to 20 per cent errors would be introduced if the earth s layered structure were ignored the effect of layering is strongest for sources with a strong horizontal slip component

evidence for the subglacial meltwater origin and late quaternary lacustrine environment of bateau channel eastern lake ontario bateau channel is the smallest and most northerly of the three outlets of lake ontario near its narrowest point 125 m at present water level it is 60 m deep making it one of the deepest places

integration of insar time series analysis and water vapor correction for mapping postseismic motion after the 2003 bam iran earthquake atmospheric water vapor effects represent a major limitation of interferometric synthetic aperture radar insar techniques including insar time series ts approaches e g persistent or permanent scatterers and small baseline subset for the first time this paper demonstrates the use of insar ts with precipitable water vapor insar ts pwv correction model for deformation mapping we use medium resolution imaging spectrometer meris near infrafred nir water vapor data for insar atmospheric correction when they are available for the dates when the nir data are blocked by clouds an atmospheric phase screen aps model has been developed to estimate atmospheric effects using partially water vapor corrected interferograms cross validation reveals that the estimated aps agreed with meris derived line of sight path delays with a small standard deviation 0 3 0 5 cm and a high correlation coefficient 0 84 0 98 this paper shows that a better ts of postseismic motion after the 2003 bam iran earthquake is achievable after reduction of water vapor effects using the insar ts pwv technique with coincident meris nir water vapor data

the 1989 loma prieta earthquake imaged from inversion of geodetic data we invert geodetic measurements of coseismic deformation from the 1989 ms7 1 loma prieta earthquake to determine the geometry of the fault and the distribution of slip on the fault plane the data include electronic distance measurements global positioning system and very long baseline interferometry vectors and elevation changes derived from spirit leveling the fault is modeled as a rectangular dislocation surface in a homogeneous elastic half space first we assume that the slip on the fault is uniform and estimate the position orientation and size of the fault plane using a nonlinear quasi newton algorithm the best fitting dislocation strikes n48 4 w and dips 76 9 sw consistent with the trend of the aftershock zone and moment tensor solutions bootstrap resampling of the data is used to graphically illustrate the uncertainty in the location of the rupture plane the 95 confidence envelope overlaps the aftershock zone arguing that there is not a significant discrepancy between the geodetic data and the aftershock locations second we estimate the slip distribution using the best fitting uniform slip fault orientation but increase the fault length to 40 km and the downdip width to 18 km the fault is divided into 162 subfaults 18 along strike and 9 along dip each subfault is allowed to have constant right lateral and reverse components of slip we then solve for the slip on each subfault that minimizes a linear combination of the norm of the weighted data residual and the roughness of the slip distribution the smoothing parameter which determines the relative weight put on fitting the data versus smoothing the slip distribution is chosen by cross validation simulations indicate that cross validation estimates of the smoothing parameter are nearly optimal the preferred slip distribution is very heterogeneous with maximum strike slip and dip slip of about 5 and 8 m respectively located roughly 10 km north of the hypocenter there is insignificant dip slip in the southeastern most part of the fault causing the rake to vary from nearly pure right lateral in the southeast to oblique right reverse in the northwest the change in rake is consistent with a uniform stress field if the fault dip increases by about 10 toward the southeast as indicated by the aftershock locations there was little slip above 4 km depth consistent with the observation that there was little if any surface rupture

surface displacements and source parameters of the 2003 bam iran earthquake from envisat advanced synthetic aperture radar imagery 1 the mw 6 6 26 december 2003 bam iran earthquake was one of the first earthquakes for which envisat advanced synthetic aperture radar asar data were available using interferograms and azimuth offsets from ascending and descending tracks we construct a three dimensional displacement field of the deformation due to the earthquake elastic dislocation modeling shows that the observed deformation pattern cannot be explained by slip on a single planar fault which significantly underestimates eastward and upward motions se of bam we find that the deformation pattern observed can be best explained by slip on two subparallel faults eighty five percent of moment release occurred on a previously unknown strike slip fault running into the center of bam with peak slip of over 2 m occurring at a depth of 5 km the remainder occurred as a combination of strike slip and thrusting motion on a southward extension of the previously mapped bam fault 5 km to the east

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

effect of crustal layering upon dislocation modeling slip distribution at depth on a fault may be inferred from the deformation observed on the surface in inverting the surface deformation data to obtain the slip distribution the earth is generally approximated by an elastic half space slip distributions inferred from a half space model may contain artifacts including zones of reversed slip due solely to effects of layering in the real earth this effect is demonstrated for a vertical strike slip fault in an earth consisting of an elastic layer overlying an elastic half space slip on the fault is taken to be independent of the along strike coordinate i e antiplane strain is assumed for a given slip distribution in this model the slip distribution on a similar fault in an elastic half space is found that produces the identical surface deformation comparison of the two slip distributions reveals structure introduced into the half space equivalent slip profile by crustal layering the comparisons suggest that low resolution inversion schemes e g single screw dislocation models are not drastically affected by earth structure but attempts at detailed inversion are likely to produce profiles contaminated by artifacts of earth structure

fault mechanics and post seismic deformation at bam se iran the extent to which aseismic deformation relaxes co seismic stress changes on a fault zone is fundamental to assessing the future seismic hazard following any earthquake and in understanding the mechanical behaviour of faults here we use models of stress driven afterslip and viscoelastic relaxation in conjunction with post seismic insar measurements to show that there has been minimal release of co seismic stress changes through post seismic deformation following the 2003 mw 6 6 bam earthquake our analysis indicates the faults at bam remain predominantly locked suggesting that the co plus interseismically accumulated elastic strain stored downdip of the 2003 rupture patch may be released in a future mw 6 earthquake our observations and models also provide an opportunity to probe the growth of topography at bam we find that for our modelled afterslip distribution to be consistent with forming the sharp step in the local topography over repeated earthquake cycles and also to be consistent with the geodetic observations requires either 1 far field tectonic loading equivalent to a 2 10 mpa deviatoric stress acting across the fault system which suggests it supports stresses 60 100 times less than classical views of static fault strength or 2 that the fault surface has some form of mechanical anisotropy potentially related to corrugations on the fault plane that controls the sense of slip

global compilation of interferometric synthetic aperture radar earthquake source models 1 comparisons with seismic catalogs 1 while many earthquakes have now been studied using interferometric synthetic aperture radar insar data a full assessment of the quality and additional value of insar source parameters compared to seismological techniques is still lacking we compile a catalog of source models obtained using insar and estimate the corresponding centroid moment tensor cmt parameters we refer to this compilation as the icmt archive we compare source parameters from over 70 insar studies of 57 global earthquakes with those in the global cmt gcmt international seismological centre isc and engdahl hilst buland ehb seismic catalogs we find an overall good agreement between fault strike dip and rake values in the gcmt and icmt archives likewise the differences in seismic moment between these two archives are relatively small and we do not find support for previously suggested trends of insar leading to larger moments than seismic data however epicentral locations show substantial discrepancies which are larger for the gcmt median differences of 21 km than for the ehb and isc catalogs median differences of 10 km since insar data have a high spatial resolution and thus should map epicentral locations accurately this allows us to obtain a first independent estimate of epicentral location errors in the seismic catalogs earthquake depths from insar are systematically shallower than those in the ehb catalog with a median of differences of 5 km while this trend may be partly due to unmodeled crustal complexity it is also compatible with the observation that the rupture of crustal earthquakes tends to propagate upward in the seismogenic layer

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 1990 rudbar tarom iranian earthquake sequence evidence for slip partitioning the rudbar tarom iran earthquake june 20 1990 ms 7 7 occurred in the high alborz mountains south of the caspian sea in northwest iran although the structural style of the region is dominated by reverse faulting and folding the focal mechanisms of the events indicate pure right lateral strike slip motion we have studied the source parameters of the 11 largest aftershocks ms 4 6 using three different methodologies 1 joint inversion of teleseismic and regional distance body waves 2 single station moment tensor inversion ssmt and 3 comparison of entire wave trains to those of master events the aftershocks show a clear bipolar distribution thrusting earthquakes on nw se trending planes and strike slip mechanisms with fault geometry similar to that of the mainshock we interpret the faulting behavior of the 1990 earthquake sequence to indicate slip partitioning in northwest iran the arabian and eurasian plates are converging in a ne direction and the alborz mountains are undergoing shortening and left lateral shear this oblique motion results in dominantly thrusting earthquakes and infrequent strike slip earthquakes

horizontal coseismic deformation of the 2003 bam iran earthquake measured from spot 5 thr satellite imagery 1 on 26 december 2003 a destructive mw 6 5 earthquake occurred in kerman province iran killing more than 30 000 people around the ancient city of bam we map the fault zone and determine the slip distribution using sub pixel correlation of images taken by the spot 5 thr sensor before and after the main shock our results show that the surface displacement occurred on a blind fault oriented n174 and located south of bam a 15 km along strike profile depicts a distribution with a maximum displacement of 1 2 0 15 m near the centre of the fault the mean slip that we infer 0 77 0 05 m is much higher than the ground displacement measured in the field 0 2 m we suggest that field measured displacements are underestimated due to slip accommodation within an 500 m wide shear zone furthermore we demonstrate for the first time the relevancy of 2 5 m spot 5 thr images for sub pixel ground displacement measurements

stress field associated with the rupture of the 1992 landers california earthquake and its implications concerning the fault strength at the onset of the earthquake we investigate the space and time history of the shear stress produced on the fault during the 1992 landers earthquake the stress is directly calculated from the tomographic image of slip on the fault derived from near source strong motion data the results obtained shed some light on why the earthquake rupture cascaded along a series of previously distinct fault segments to produce the largest earthquake in california in over 40 years rupture on the 30 km long northernmost segment of the fault was triggered by a large dynamic increase of the stress field of the order of 20 to 30 mpa produced by the rupturing of the adjacent fault segments such a large increase was necessary to overcome the static friction on this strand of the fault unfavorably oriented in today s tectonic stress field this misorientation eventually led to the arrest of rupture the same mechanism explains why rupture broke only a small portion of the johnson valley fault on which the earthquake originally started before jumping to an adjacent fault more favorably oriented we conclude from these results that the dynamic stress field could not sustain and drive the rupture along the strongly misoriented nw se strands of the preexisting fault system instead the dynamic stress field produced new fractures favorably oriented in a n s direction and connecting parts of the old fault system

a fault model for the 1989 kilauea south flank earthquake from leveling and seismic data the geometry of the fault that ruptured during the m6 1 south flank earthquake on kilauea volcano in 1989 is determined from leveling data the elastic dislocation in a homogeneous elastic half space that best fits the data is found using a nonlinear inversion procedure the best fitting model is a gently dipping thrust fault that lies at 4 km depth this is significantly shallower than the 9 km hypocentral depth determined from the local seismic network two dimensional finite element calculations indicate that at least part of this discrepancy can be attributed to the focusing of the surface deformation by the upper few kilometers of compliant low density lavas we conclude that it is important to include realistic elastic structure to estimate source geometry from geodetic data

the resolving power of coseismic surface displacement data for fault slip distribution at depth 1 the spatial slip distribution of the august 17 1999 izmit turkey earthquake has previously been determined from both geodetic and seismological data though the models derived agree on a broad scale they are significantly different in detail these differences could be due to the inversion techniques applied and or additional constraints implemented and or be due to poor resolution it is also conceivable that the relative agreement at larger scales results in part from a resolution artifact common to all models to investigate this we perform a resolution analysis of fault slip models based on the inversion of surface displacement data assuming the theory of elastic dislocations in a half space and adopting a parameterization for which model predictions are capable of fitting the spatial variations of the data the inverse problem proves to be intrinsically ill conditioned

coseismic slip resolution and post seismic relaxation time of the 1999 chi chi taiwan earthquake as constrained by geological observations geodetic measurements and seismicity summary we analysed the surface displacements estimated by global positioning system gps mea surements and systeme probatoire d observation de la terre spot image correlation and the seismicity change induced by the mw 7 6 1999 september 20 chi chi earthquake we first modelled the seismogenic zone for which we introduced a realistic geologically constrained ramp and flat geometry and estimated by joint inversion of the gps and spot data the co seismic slip distribution stressing the resolution of the model parameters the fair adjustment indicates that the ramp and flat geometry is consistent with the geodetic measurement the cal culated coseismic slip increases both towards the surface and northwards with maximum slip of approximately 15 m in good agreement with the observed surface rupture and previously ob tained slip models based on seismic waveforms this distribution may be represented to a good approximation by a linear increase of slip with a constant azimuth in the plate convergence direction special emphasis is given to the analysis of the model resolution which sharply decreases with depth in spite of the exceptionally well distributed and high quality inverted data this resolution decrease expected for any slip distribution based on surface observations only led us then to examine the seismicity as independent data to test our model following the static stress triggering hypothesis the model is accurately defined in terms of coulomb stress change in the central part of the rupture where the fault geometry is well constrained by seismic profile in contrast at the southern and northern ends it is less appropriate however the static stress triggering approach is not precise enough to determine whether fault geometry or slip distribution is less suitable we thus conclude that the analysis of seismicity in terms of coulomb stress change might not allow us to examine small scale features of seismogenic zones finally we discuss post seismic relaxation from the temporal variation of seismicity rate in contrast to the relaxation time of 0 23 0 90 yr inferred from post seismic permanent gps measurements we found that the decay of aftershock sequence follows omori s law with an 8 14 yr relaxation time we suggest that this discrepancy results from the coexistence of several different processes not all associated with the production of aftershocks

3 d finite element modelling of deformation and stress associated with faulting effect of inhomogeneous crustal structures summary modelling of deformation and stress caused by earthquake faulting or fault motion based on a homogeneous elastic half space model does not include crustal rigidity layering and lateral variations geological data and seismic surveys indicate that the crust is elastically inhomogeneous and that rigidity layering and heterogeneities are likely to affect the magnitude and pattern of deformation and stress we use the finite element method fem to investigate deformation and stress generated by strike slip tensile and thrust faulting considering rigidity layering in the crust for a fault with a dimension of 25 10 km and a slip value of 0 5 m cutting through the top 10 km of the crust the deformation and stress change associated with the three modes of faulting are calculated for an island arc crustal structure represented by three models of rigidity layering the results indicate i the maximum effect in horizontal displacements due to crustal layering for the investigated models is 19 7 mm and 28 8 mm for strike slip and tensile faulting respectively for thrust faulting the effect is up to 58 3 mm this remarkable effect is due to the offset of layers by thrust faulting which dynamically changes the crustal structure both horizontally and vertically ii the maximum effect in vertical deformation due to crustal rigidity layering for strike slip and tensile faulting is 5 mm in contrast the effect for thrusting is 30 3 mm iii the effect in the shear stress change at a depth of 7 5 km for the different styles of faulting ranges from 0 02 mpa to 0 10 mpa an additional modelling analysis of subduction thrusting at the japan trench with a detailed structural model based on seismic surveys further confirms the significant distortion caused by a homogeneous model that ignores crustal structural information overall the effect of crustal rigidity layering is at least 20 per cent for surface deformation and 15 per cent for stress changes at depth in light of the present accuracy of global positioning system gps observations 2 mm and the estimate of stress change required for earthquake hazard analysis ca 0 01 mpa the results from the numerical experiments indicate that crust inhomogeneity rigidity layering and lateral variations should be included in any quantitative models of faulting

the 2003 december 26 bam earthquake iran mw 6 6 aftershock sequence summary from 2003 december 29 to 2004 january 30 a dense seismological network of 23 stations was installed in the epicentral area of the 2003 december 26 bam earthquake to study the aftershock seismicity we select the 331 earthquakes recorded at a minimum of 10 stations with rms less than 0 1 s and uncertainties less than 1 km to infer the precise geometry of the seismicity in the fault region we also process the data with the double difference technique to confirm the results the aftershock cluster is 25 km long trends north south and is located 5 km west of the bam baravat escarpment exactly beneath the observed surface breaks at depth aftershocks are concentrated between 6 and 20 km beneath the upper layer of relatively low velocity that experienced the maximum slip and they dip slightly westward the southernmost part of the aftershock cluster is narrow and defines the rupture zone that is likely the bam baravat fault at depth however it is unlikely that it is connected at surface to the bam baravat escarpment but more likely to the co seismic ruptures south of bam on the contrary the distribution of the northernmost aftershocks spread into a more complex pattern which is consistent with a northward propagation of the rupture along the fault plane the focal mechanisms are consistent with right lateral strike slip faulting on n s trending faults parallel to the bam baravat escarpment

geodetic investigation of the 13 may 1995 kozani grevena greece earthquake the ms 6 6 13 may 1995 kozani grevena earthquake struck a region of low historical seismic activity which includes a 10 year old triangulation network in northern greece after the earthquake monuments from this network were occupied with gps to measure co seismic displacements inversion of the co seismic displacement field to yield a source mechanism is achieved by use of a hybrid simplex monte carlo method which requires no a priori constraints the model focal mechanism agrees well with the global cmt solution and locally observed aftershocks but implies a significantly higher scalar moment than do seismological or sar interferometry studies and has a longer fault length than the model based on sar interferometry

a joint analysis of gps motions and insar to infer the coseismic surface deformation of the izmit turkey earthquake summary from a joint analysis of gps and insar data we have determined the kinematic coseismic surface deformation of the 1999 august 17 izmit turkey earthquake in terms of strain rotation and fault slip the fault slip contribution shows two distinct peaks one of 4 m of slip at golcuk and a second of 2 9 m slip near sapanca lake the strain field portrays four distinct quadrants reflecting the earthquake focal mechanism the transition between the quadrants is not centred on the epicentre of the event but shifted eastwards north of the fault and westwards south of the fault this shift is the result of a two stage source rupture process caused by the step over features in the fault geometry this rupture process also induced a distinct asymmetry in the displacement field across the fault we obtain left lateral shear strains along the sakarya segment that is the result of a subsequent source nucleating at the akyazi gap inducing failure on the easternmost segments strong interaction is also observed from a consecutive source near hersek finally we deduce that the izmit earthquake has released most of the strain that has accmulated since the last main event on this stretch of the north anatolian fault in 1719

deformation during the 12 november 1999 duzce turkey earthquake from gps and insar data only 87 days after the mw 7 5 17 august 1999 izmit earthquake the duzce earthquake ruptured a ca 40 km long adjoining strand of the north anatolian fault naf system to the east we used displacements of 50 global positioning system gps sites together with interferometric synthetic aperture radar insar range change data spanning the event to estimate the geometry and slip distribution of the coseismic rupture postseismic deformation transients from the duzce earth quake and the preceding i zmit event that are included in some of the measurements are corrected for using dislocation models fit to gps data spanning the various time periods nonlinear inversions for fault geometry indicate that the rupture occurred on a ca 54 north dipping oblique normal right lateral fault distributed slip inver sions indicate maximum strike slip near the center of the duzce fault close to the earthquake hypocenter slip magnitude and depth of faulting decrease to the west and east of the hypocenter both gps and insar data suggest that normal slip is restricted to the shallow portion of the rupture the duzce earthquake had the highest slip to rupture length ratio of any historic earthquake along the naf

patterns of historical earthquake rupture in the iranian plateau the iranian plateau accommodates the 35 mrn yr convergence rate be tween the eurasian and arabian plates by strike slip and reverse faults with relatively low slip rates in a zone 1000 km across although these faults have only locally been the subject of paleoseismological studies a rich historical and archeological record spans several thousand years long enough to establish recurrence intervals of 1000 to 5000 yr on individual fault segments several clusters of earthquakes provide evidence of interaction among reverse and strike slip faults probably due to adjacent faults being loaded by individual earthquakes the dasht e bayaz sequence of 1936 to 1997 includes earthquakes on left lateral right lateral and reverse faults the neyshabur sequence of four earthquakes between 1209 and 1405 respected the seg ment boundary between the neyshabur and binalud reverse fault systems the two pairs of earthquakes may have ruptured different faults in each segment similar to the 1971 and 1994 san fernando california earthquakes the 1978 tabas reverse fault earthquake was preceded by the 1968 ferdows earthquake part of the dasht e bayaz sequence the north tabriz fault system ruptured from southeast to north west in three earthquakes from 1721 to 1786 a previous cluster may have struck this region in 855 to 958 the mosha fault north of tehran ruptured in three earthquakes in 958 1665 and 1830 five large earthquakes struck the tehran region from 743 to 1177 but only two that large have struck the area since 1177 other earthquakes occurred in pairs in the talesh mountains near the caspian sea 1863 1896 the iran turkey border 1840 1843 and the nayband gowk fault system both 1981 other historical events did not occur as parts of sequences the historic seismic moment release in iran accounts for only a small part of the plate convergence rate which may be due to aseismic slip or to the iranian historical record long as it is being too short to sample long term deformation across the plateau no historic earthquakes of m 8 have struck iran however several long straight strike slip faults doruneh west neh east neh and nayband have not sustained large historical earthquakes raising the possibility that these long faults could produce earthquakes of m 8 thereby removing at least part of the apparent slip deficit an increased understanding of iran s seismic hazard could be obtained by an extensive paleoseismology program and space geodetic arrays supplementing the abundant historical and archaeological record

analysis of near source static and dynamic measurements from the 1979 imperial valley earthquake gross features of the rupture mechanism of the 1979 imperial valley earthquake ml 6 6 are inferred from qualitative analysis of near source ground motion data and observed surface rupture a lower bound on the event s seismic moment of 2 5 1025 dyne cm is obtained by assuming that the average slip over the whole fault plane equals the average surface rupture 40 5 cm far field estimates of moment suggest an average slip over the fault plane of 105 cm from which a static stress drop of 11 bars is obtained an alternative slip model consistent with the far field moment has 40 5 cm of slip in the upper 5 km of the fault and 120 cm of slip in the lower 5 km this model suggests a static stress drop of 39 bars from the lower estimate of 11 bars an average strain drop of 32 strain is derived this strain drop is four times greater than the strain that could have accumulated since the 1940 el centro earthquake based on measured strain rates for the region hence a major portion of the strain released in the 1979 main shock had been accumulated prior to 1940 unusually large amplitude 500 to 600 cm sec2 vertical accelerations were recorded at stations e05 e06 e07 e08 eda of the ei centro array and the five stations of the differential array near eda although the peak acceleration of 1705 cm sec2 at e06 is probably amplified by a factor of 3 due to local site conditions these large amplitude vertical accelerations are unusual in that they are evident on only a few stations all of which are near the fault trace and at about the same epicentral range two possible explanations are considered first that they are due to a direct p wave generated from a region about 17 km north of the hypocenter or second that they are due to a pp phase that is unusually strong in the imperial valley due to the large p wave velocity gradient in the upper 5 km of the imperial valley based on the distribution of both the horizontal and vertical offsets it is likely that the rupture went beyond stations e06 and e07 during the main shock by exploiting the antisymmetry of the parallel components of particle velocity between e06 and e07 and by examining polarization diagrams of the particle velocity at e06 and e07 an average rupture velocity in the basement of 2 5 to 2 6 km sec between the hypocenter and station e06 is obtained in addition several lines of evidence suggest that the imperial fault dips about 75 to the ne

reassessment of the source of the 1976 friuli ne italy earthquake sequence from the joint inversion of high precision levelling and triangulation data summary in this study we revisit the mechanism of the 1976 friuli ne italy earthquake sequence main shocks mw 6 4 5 9 and 6 0 we present a new source model that simultaneously fits all the available geodetic measurements of the observed deformation we integrate triangulation measurements which have never been previously used in the source modelling of this sequence with high precision levelling that covers the epicentral area we adopt a mixed linear non linear optimization scheme in which we iteratively search for the best fitting solution by performing several linear slip inversions while varying fault location using a grid search method our preferred solution consists of a shallow north dipping fault plane with assumed azimuth of 282 and accommodating a reverse dextral slip of about 1 m the estimated geodetic moment is 6 6 1018 nm mw 6 5 in agreement with seismological estimates yet our preferred model shows that the geodetic solution is consistent with the activation of a single fault system during the entire sequence the surface expression of which could be associated with the buia blind thrust supporting the hypothesis that the main activity of the eastern alps occurs close to the relief margin as observed in other mountain belts the retrieved slip pattern consists of a main coseismic patch located 3 5 km depth in good agreement with the distribution of the main shocks additional slip is required in the shallower portions of the fault to reproduce the local uplift observed in the region characterized by quaternary active folding we tentatively interpret this patch as postseismic deformation afterslip occurring at the edge of the main coseismic patch finally our rupture plane spatially correlates with the area of the locked fault determined from interseismic measurements supporting the hypothesis that interseismic slip on the creeping dislocation causes strain to accumulate on the shallow above 10 km depth locked section assuming that all the long term accommodation between adria and eurasia is seismically released a time span of 500 700 years of strain accumulating plate motion would result in a 1976 like earthquake

coulomb stress changes and secondary stress triggering during the 2003 mw 6 6 bam iran earthquake abstract the 26 december 2003 mw 6 6 bam earthquake is one of the most destructive events in the recorded history of iran good variable slip fault models and precise aftershock data enabled us to calculate coulomb stress changes on the surrounding faults optimally oriented faults and the aftershock nodal planes to learn whether they were brought closer to failure we also test the role of secondary stress on the aftershocks triggering calculated stress on the surrounding faults showed that the southern part of the gowk fault and middle part of the dalfard and bam faults received positive stress changes stress also increases at the ends of the ruptured fault plane to expand it our calculations showed that deeper part of the bam fault planes received positive stress changes due to slipping on the shallow depth it can lead to the occurrence of aftershocks and enhance the probability of large events in the future that represent a substantial remaining seismic hazard to the reconstructed city of bam by imparting stress on optimally oriented faults the correlation between coulomb stress changes and aftershock distribution is investigated obtained results showed good correlation between coulomb stress change and seismicity from 331 well located aftershock hypocenters about 270 events 81 are located in the positive stress changes area the imparted stress due to the main shock and secondary aftershocks on the nodal planes of the 158 aftershocks is calculated the results show that the imparted stress due to main shock encouraged about 60 1 of nodal planes and 77 8 of the chosen nodal planes of aftershocks and added secondary aftershock encouraged about 81 6 of chosen nodal planes in other word by adding secondary triggering stress coulomb index for chosen nodal planes increased from 0 778 to 0 816 and about 80 of aftershocks receive greater positive stress changes

joint inversion of broadband teleseismic and interferometric synthetic aperture radar insar data for the slip history of the mw 7 7 nazca ridge peru earthquake of 12 november 1996 1 the slip distribution of the 12 november 1996 mw 7 7 peru earthquake is determined using broadband teleseismic waveforms a differential sar interferogram interferometric synthetic aperture radar insar and a fault parametrization allowing slip and rupture velocity to vary along the rupture plane both data sets are inverted jointly to limit the trade off between the space and time aspects of the rupture the earthquake fault plane is located at the subduction interface it strikes parallel to the trench and dips 30 ne by inverting synthetic data we show how the insar and teleseismic data are complementary and how the joint inversion produces a gain in the spatial and temporal resolution of the slip model even with a sar interferogram that covers only part of the coseismic deformation the rupture of the 1996 peru event initiated on the southern flank of the subducted nazca ridge and propagated unilaterally toward the southeast along strike for more than 100 km at a depth between 20 and 40 km the area of maximum slip 6 7 m is located 50 km southeast of the hypocenter the total seismic moment is 4 4 1020 n m our joint inversion the source time function is approximately 60 s long and presents three major pulses of moment release the dominant one which occurred between 30 and 45 s does not correspond to the area of largest slip but to the rupture of a wide zone located about 100 km away from the hypocenter where slip reaches only 2 3 m computed coseismic coastal uplift correlates well with the location of raised marine terraces and with the topography of the coastal cordillera suggesting that these features may be related to the repetition of 1996 type events at the interface between the nazca ridge and the south american plate

simulation of selected strong motion records of the 2003 mw 6 6 bam earthquake se iran the modal summation ray tracing methods in the wkbj approximation

erosion of bedrock by subglacial meltwater georgian bay ontario a regional view a spectacular series of sculpted erosional forms s forms is mapped and described from a 70 km wide area along the shore of georgian bay ontario which except for a scattered boulder lag has been swept clean of sediment a great variety of sculpted forms is described and illustrated and grouped into three classes transverse longitudinal and nondirectional forms transverse forms comprise transverse troughs muschelbruche sichelwannen and comma forms longitudinal forms comprise spindle flutes cavettos and furrows and nondirectional forms consist of undulating surfaces and potholes transverse forms are preferentially located on stoss slopes and longitudinal forms on lee slopes of rock rises undulating nondirectional forms are found on distal slopes and potholes at major breaks in slope this correlation of form and bed topography suggests that relief exerts considerable control on both form and location form geometry is also inferred to be related to coherent flow structures and their int

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

s wave anisotropy in the aftershock region of the 2003 bam iran earthquake mw 6 5 abstract the 2003 bam earthquake mw 6 5 occurred in the southeastern iran on december 26 2003 we studied s wave anisotropy using the aftershock data observed at 5 stations in and around the aftershock region the fast polarization direction of shear wave splitting at the stations near the aftershock region is almost ne sw which corresponds to the maximum compressive stress trend the p axis of the main shock it is suggested that the inferred anisotropy might be caused by a systematic alignment of cracks resulting from the present day stress field the fast direction at the station just above the fault zone shows ew direction normal to the fault strike the fault normal alignment of cracks introduces a significant reduction of shear stress of the fault which suggests a high stress drop and large slip asperity another possible explanation for different result at the station from that of other stations is the effect of inhomogeneous velocity structure in and around the fault damaged zone the delay time of the split s waves ranges between 20 and 100 ms large delay time area is found in the shallower part of the fault zone with high aftershock activity assuming a uniform distribution of anisotropy inside and outside the aftershock region we estimated that the crack densities are 0 013 inside and 0 004 outside the aftershock region it may show more intense cracks within the high active region of aftershocks

drumlins and catastrophic subglacial floods shaw j kvill d and rains b 1989 drumlins and catastrophic subglacial floods in j menzies and j rose editors subglacial bedforms drumlins rogen moraine and associated subglacial bedforms sediment geol 62 177 202 a number of lines of evidence are shown to be consistent with drumlin formation by catastrophic meltwater floods drumlins are associated with landforms related to such floods and landscapes produced by outburst floods in extragiacial areas contain drumlin like landforms some drumlins which contain mainly residual materials are compared to similar forms covering a wide range of scales and are interpreted to be scour remnant ridges produced by the action of horseshoe vortices on subgiacial materials these vortices are a product of flow separation in turbulent fluids and this interpretation implies drumlin formation by meltwater other drumlin calied cavity fill drumlins have distinctive shapes that are analogous with infilled erosional marks produced by turbulent separated flows these drumlins are interpreted as the infills of cavities eroded upwards into glacier beds by broad subgiacial meltwater sheetflows the sedimentology and internal structure of the cavity fill drumlins indicate rapid deposition from hyperconcentrated flow clast shape surface texture and lithology are consistent with the short distance of giaciofhivial transport predicted by the cavity fill hypothesis estimates of flow discharge 0 6 6 x 107 m3 s total volume of flow 84 1 103 km3 and flow duration 16 162 days are given for the catastrophic flood proposed to have produced the livingstone like saskatchewan drumlin field subgiacially derived floods are used to explain the sudden drainage of extraglacial lakes and major depositional events in proglacial lakes and it is suggested that they might have contributed to the lid of cold freshwater over the north atlantic held to have caused a late glacial cooling event the flood hypothesis requires extensive subgiacial lakes to have occurred beneath the laurentide and fennoscandian ice sheets which if they existed must have influenced the form and behaviour of these major bodies of ice

source fault structure of the 2003 bam earthquake southeastern iran inferred from the aftershock distribution and its relation to the heavily damaged area existence of the arg e bam fault proposed 1 we investigate the hypocenter distribution of aftershocks of the december 26 2003 bam earthquake mw 6 5 by using a temporal seismic network the hypocenters distribute linearly over about 20 km in parallel with a line 3 5 km west of the geological bam fault and extend from the south of bam city to the heavily damaged area in the eastern part of the city including the historical mud brick citadel arg e bam based on the hypocenter distribution we propose a schematic 3 d structural model of a new fault that we have named the arg e bam fault we suggest that the bam earthquake occurred not in the bam fault but in the arg e bam fault bam city is located just above northern part of the arg e bam fault and also on the rupture propagation direction from the asperity this may be one of the main reasons why eastern part of bam city suffered the heaviest damage

spatial relation between main earthquake slip and its aftershock distribution 1 we examine where aftershocks occur relative to the spatial distribution of the main shock slip using data from several recent large earthquakes no universal relation between high and low moment regions and high or low aftershock occurrence or vice versa is found we generally find that few and usually the smaller aftershocks occur in the high slip regions of the fault a notable exception to this being the great 1996 biak indonesia subduction zone earthquake in all cases aftershocks occur on favorably oriented planes of weakness in regions of increased postseismic stress generally they are clustered at both ends of faults but examples where aftershocks occur only at one end or where there is no clustering at the ends are found aftershock clusters are also found at the edge of unbroken barriers and regions of rapid transition from high to low slip within the main fault area we identify examples of geometrical and inhomogeneous barriers and sharp and dull stress concentrations rupture in the main shock is generally found to nucleate in the region of low slip or at the edge of high slip regions the 1996 biak earthquake again being the only exception nucleating in a very high slip region off fault aftershocks are found for all earthquakes in this study and they sometimes rupture the nodal plane conjugate to the main shock fault plane

measuring near field coseismic displacements from sar images application to the landers earthquake we describe a procedure to compute sar interferograms based on the compensation of the images mis registrations due to the ground deformation and on a specific adaptive filtering to improve the snr in the measurement where displacement gradients are large applied to the landers earthquake case the registration reduces the phase noise by 20 rms near the fault and the interferogram reveals fringes that would not show out otherwise the interferogram is validated by comparison in the far field with a gps edm based model the inferred displacement field shows discontinuities that follow the fault within few hundred meters close to the fault the measured displacements differ significantly from that predicted by elastic modeling of the far field data interferometry and measurements derived from the images amplitude offsets appear to be complementary techniques providing original measurements that may help to reconcile seismological and geodetic models of coseismic deformation with measurements of fault slip at the surface

estimating slip distribution for the izmit mainshock from coseismic gps ers 1 radarsat and spot measurements we use four geodetic satellite systems global positioning system gps european remote sensing ers radarsat and satellite pour l9observation de la terre spot to measure the permanent deformation field produced by the izmit earthquake of 17 august 1999 we emphasize measurements from interferometric analysis of synthetic aperture radar sar images acquired by ers and radarsat and their geodetic uncertainties the primary seismological use of these data is to determine earthquake source parameters such as the distribution of slip and the fault geometry after accounting for one month9s postseismic deformation tropospheric delay and orbital gradients we use these data to estimate the distribution of slip at the time of the izmit mainshock the different data sets resolve different aspects of the distribution of slip at depth although these estimates agree to first order with those derived from surface faulting teleseismic recordings and strong motion careful comparison reveals differences of 40 in seismic moment we assume smooth parameterization for the fault geometry and a standard elastic dislocation model the root mean square residual scatter is 25 mm and 11 mm for the ers and radarsat range changes respectively our estimate of the moment from a joint inversion of the four geodetic data sets is m 0 1 84 10 20 n m a moment magnitude of m w 7 50 these values are lower than other estimates using more realistic layered earth models given the differences between the various models we conclude that the real errors in the estimated slip distributions are at the level of 1 m the prudent geophysical conclusion is that coseismic slip during the izmit earthquake tapers gradually from approximately 2 m under the hersek delta to 1 m at a point 10 km west of it we infer that the yalova segment west of the hersek delta may remain capable of significant slip in a future earthquake

the effect of elastic layering on inversions of gps data for coseismic slip and resulting stress changes strike slip earthquakes we investigate the effect of depth dependent elasticity on slip inversions and coseismic stress change estimates for large strike slip earthquakes using a series of hypothetical models and the 1999 izmit turkey earthquake as examples slip inversions are performed using both semianalytical and finite element solutions for surface displacements due to a shear dislocation in layered and uniform elastic earth models we find that incorporating realistic increases to shear modulus with depth in our inversions increases recovered centroid depth and seismic potency relative to uniform elastic half space models recovered seismic moment is up to 40 greater for models incorporating depth dependent than it is for uniform elastic half space models incorporating depth dependent also increases our estimate of the maximum slip depth for the izmit turkey earthquake to at least 20 km our estimates of coseismic stress change in the upper crust do not change significantly when we incorporate depth dependent elasticity in our inversions as long as slip at depth is tuned increased to match surface displacements coseismic differential stresses in the lower crust increase by up to a factor of 3 in the near field but further from the fault stresses from layered and uniform elastic models are approximately equal with increasing depth in the mantle the ratio of modeled differential stresses for the layered and uniform elastic models approaches the ratio of mantle values for these two models we conclude that models of postseismic viscoelastic relaxation following large strike slip earthquakes should incorporate depth dependent elasticity but that uniform elastic half space models are adequate to calculate coseismic coulomb stresses in the upper crust for most triggering studies

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

field and teleseismic observations of the 1981 golbaf sirch earthquakes in se iran summary in 1981 june and july two large earthquakes occurred on the gowk fault system in south east iran both earthquakes were associated with surface faulting showing a combination of reverse and right lateral strike slip motion on parallel adjacent faults striking north south and dipping both east and west such motion can be seen to have occurred in the recent past and is responsible for the formation of elongated alluvium filled depressions in the footwall region common to both the east and west dipping faults the earthquake of june 11 involved motion along about 15 km of the gowk fault system with a moment of about 1 0 1026 dyne cm the earthquake of july 28 was larger and occurred farther north with movement along at least 65km of the gowk fault system and a moment of about 7 1026 dyne cm surface faulting in both earthquakes was complex and spread over several kilometres width on en echelon fault segments as well as on faults dipping both east and west the long period wwssn seismograms of these two mainshocks are unusually complicated and clearly made up of several individual subevents sensible interpretation of these waveforms without guidance from the surface faulting and the long period sro moment tensor inversion of dziewonski woodhouse would be impossible however a combination of these three data sources allows a geologically plausible interpretation of the rupture processes in these earthquakes to be made although the faulting in both mainshocks was on the same large scale feature the gowk fault the rupture zones of the two earthquakes did not apparently overlap and were separated by a gap of 5 km along strike in which both coseismic and recent geological displacements are very small rupture in both mainshocks appears to have nucleated near this gap and to have propagated away from it other such gaps are visible along the irregular displacement of the northern fault break and may have been the nucleation positions for individual subevents of the july 28 earthquake recognition of such nucleation sites is of obvious importance to earthquake prediction efforts

imaging coseismic rupture in far field by slip patches summary since the end of the 1970s teleseismic waves are used routinely to infer the first order characteristics of the event location depth duration focal mechanism but finding the second order kinematic parameters spatial distribution of slip rupture velocity and more basically the discrimination between the fault plane and the other nodal plane of distant events remains a difficult task classically these events are studied by two different methods either they are seen as a succession of subevents each of which is considered as a point source or like in near field as extended sources where the kinematic parameters are retrieved on a grid the first approach is not physically satisfactory and can lead to erroneous interpretations of the

the source motion of 2003 bam iran earthquake constrained by satellite and ground based geodetic data summary the interpretation of coseismic surface deformation measurements through inversion techniques is of major importance to understand the mechanical behaviour of a seismic fault dense geodetic data sets in the vicinity of the ruptured fault provide unique constraints on detailed fault geometry and slip distribution at depth making them complementary to seismological data bam earthquake mw 6 6 2003 december 26 induced surface deformation has been precisely mapped by envisat asar interferometry and by subpixel correlation techniques applied to spot 5 and asar amplitude images these oblique and horizontal estimations of deformation have been completed with one levelling profile along the main road crossing the rupture from west to east we process these data separately and jointly in a two step inversion technique within the elastic half space theory framework our objective is to determine the dislocation model at depth that satisfies simultaneously all the geodetic constraints also we estimate the relative contribution of each geodetic data set to this inversion process we first use a stochastic direct approach called neighbourhood algorithm in order to estimate the average characteristics of the rupture and their relative uncertainty constraining in this way the geometry of the ruptured fault we then linearize the inverse problem and compute the slip distribution on the fault using a standard weighted least square technique assuming the solution is smooth to some degree at each step we discuss the optimal models their stability as well as the relative influence of each data set on the derived models parameters our preferred model reveals a shallow dislocation on a quasi vertical fault slightly dipping towards east the slip vector has a strike slip component as high as 2 m while the dip slip component seems negligible however the estimation of the resolution matrices emphasizes the fact that the details of deep fault slip distribution remain out of the scope of this ill conditioned inverse problem yet our preferred model suggests a main dislocation limited at depth between 1 and 6 km by contrast the aftershocks observed in the months following the earthquake are located just beneath the estimated main shock

offset and evolution of the gowk fault s e iran a major intra continental strike slip system abstract we use drainage reconstructions to estimate long term offsets on the gowk fault an oblique right lateral strike slip fault in eastern iran on which there have been a number of recent large earthquakes a 3 km horizontal offset is inferred from well preserved geomorphology we further identify a total cumulative offset of 12 km which produces a simple reconstruction of geomorphology across the fault filling in pull apart basins restoring rivers to linear courses across the fault trace and aligning structural and bed rock features the probable age of the gowk fault and k ar dating of offset basalts north of the study region suggest an overall slip rate of 1 5 2 4 mm year this is small compared with the overall 10 20 mm year of shear expected between central iran and afghanistan and the deficit is likely to have been accommodated on other faults east of the gowk fault drainage displaced by dextral movement leads to the development of a series of basins along the fault and a longitudinal topographic profile that resembles an asymmetric saw tooth the geomorphic evolution of the fault zone at the surface includes both normal and reverse faulting components reflecting a probable ramp and flat structure in cross section this interpretation is consistent with evidence from the analysis of seismological radar and surface rupture data in recent earthquakes

joint inversion of insar and teleseismic data for the slip history of the 1999 izmit turkey earthquake the slip history of the izmit earthquake is investigated by jointly inverting sar and teleseismic data with a multi segment variable slip finite fault model surface offsets are used as an added constraint the highest slip values 5 to 7 m of right lateral displacement are associated with a strong central asperity surrounding the hypocenter the bilateral breaking of this main asperity which lasted about 10 sec dominates the source time function from the golcuk izmit area to lake sapanca a relatively good correspondence is observed between slip at depth and at the surface but farther to the west and to the east slip tends to be confined to the near surface slip in the easternmost part of the rupture duzce segment is not well resolved our analysis finds the insar and teleseismic data to be compatible and complementary this study shows the potential of the joint inversion of both data sets for a rapid determination of the spatio temporal history of large earthquakes

co seismic displacements of the 1992 landers earthquake sequence we present co seismic displacement vectors derived from global positioning system gps measurements of 92 stations in southern california these gps results are combined with five well determined gps displacement vectors from continuously tracking stations of the permanent gps geodetic array as well as line length changes from usgs geodolite and two color laser trilateration observations to determine a self consistent set of geodetic data for the earthquake these combined displacements are modeled by an elastic dislocation representation of the primary fault rupture planes on average the model residuals are about twice the estimated measurement errors

the 1998 march 14 fandoqa earthquake mw 6 6 in kerman province southeast iran re rupture of the 1981 sirch earthquake fault triggering of slip on adjacent thrusts and the active tectonics of the gowk fault zone summary the 1998 march 14 fandoqa earthquake ms 6 6 was the penultimate in a series of five substantial earthquakes on the gowk fault system of southeast iran since 1981 all of which were associated with co seismic surface ruptures we use observations of surface faulting analysis of p and sh body waves sar interferometry and geomorphology to investigate the ruptures in these earthquakes and how they are related both to each other and to the regional active tectonics the 1998 fandoqa earthquake produced 23 km of surface faulting with up to 3 m right lateral strike slip and 1 m vertical offsets sar interferometry and seismic waveforms show that the main rupture plane dipped west at 50 and had a normal component although the surface ruptures were more complicated being downthrown to both the east and the west on steep faults in near surface sediments in addition sar interferometry shows that a nearby thrust with a similar strike but dipping at 6 w moved about 8 cm in a time interval and in a position that makes it likely that its slip was triggered by the fandoqa earthquake the 1998 surface ruptures in the gowk valley followed part of a much longer 80 km set of co seismic ruptures with smaller offsets that were observed after larger earthquakes in 1981 mw 6 6 and 7 1 the main ruptures in these 1981 earthquakes probably occurred on different deeper parts of the same fault system producing only minor reactivation of the shallower faults at the surface although the 1981 1998 earthquake sequence apparently ruptured parts of the same fault system repeatedly these earthquakes had very different rupture characteristics an important lesson for the interpretation of both palaeoseismological trenching investigations and historical accounts of earthquakes the regional kinematics which involve oblique right lateral and convergent motion are evidently achieved by a complex configuration of faults with normal reverse and strike slip components some of the complexity at the surface may be related to a ramp and flat fault geometry at depth but could also be related to the large topographic contrast of 2000 m across the fault system which separates the high kerman plateau from the low dasht e lut desert details of the fault geometry at depth remain speculative but it must be unstable and evolve with time it may be this requirement that causes the principal features of geological flower structures to develop such as series of subparallel faults which accommodate dip slip components of motion

present day crustal deformation and plate kinematics in the middle east constrained by gps measurements in iran and northern oman summary a network of 27 gps sites was implemented in iran and northern oman to measure displacements in this part of the alpine himalayan mountain belt we present and interpret the results of two surveys performed in 1999 september and 2001 october gps sites in oman show northward motion of the arabian plate relative to eurasia slower than the nuvel 1a estimates e g 22 2m m yr 1 at n8 5 e instead of 30 5 mm yr 1 at n6 e at bahrain longitude we define a gps arabia eurasia euler vector of 27 9 0 5 n 19 5 1 4 e 0 41 0 1 myr 1 the arabia eurasia convergence is accommodated differently in eastern and western iran east of 58 e most of the shortening is accommodated by the makran subduction zone 19 5 2m m yr 1 and less by the kopet dag 6 5 2m m yr 1 west of 58 e the deformation is distributed in separate fold and thrust belts at the longitude of tehran the zagros and the alborz mountain ranges accommodate 6 5 2m m yr 1 and 8 2m m yr 1 respectively the right lateral displacement along the main recent fault in the northern zagros is about 3 2m m yr 1 smaller than what was generally expected by contrast large rightlateral displacement takes place in northwestern iran up to 8 mm yr 1 the central iranian block is characterized by coherent plate motion internal deformation 2m m yr 1 sites east of 61 e show very low displacements relative to eurasia the kinematic contrast between eastern and western iran is accommodated by strike slip motions along the lut block to the south the transition zone between zagros and makran is under transpression with right lateral displacements of 11 2m m yr 1

source parameters of the 1 october 1995 dinar turkey earthquake from sar interferometry and seismic bodywave modelling abstract the 1 october 1995 m s 6 1 dinar earthquake ruptured a 10 km section of the nw se dinar civril fault there are discrepancies between the published source parameters from seismic data with seismic moments in disagreement by over a factor of two we use both sar interferometry and seismic bodywave modelling to determine earthquake source parameters an interferogram generated from ers 1 2 sar imagery spanning the event and separated by 5 months is used to derive source parameters by a downhill simplex inversion with multiple monte carlo restarts we model the displacements in the satellite line of sight initially using uniform slip on a rectangular dislocation in an elastic half space the resultant model fault plane agrees in strike and location with the observed surface break but systematic residuals exist in the line of sight deformation field resulting in a r m s residual of 20 mm in the interferogram the residuals are reduced if the depth distribution of slip is allowed to vary spatially in four segments along a continuous fault plane our best fitting solution with a r m s misfit of 8 mm reveals two distinct areas of slip on the fault plane strike 145 dip 49 rake 270 a main rupture slipping by 1 44 m between depths of 1 and 8 km becoming deeper to the se and matching the observed surface rupture and an along strike continuation to the nw of the same fault plane but between depths of 8 and 13 km and not associated with a surface break the total geodetic moment 4 5 0 1 10 18 nm is more than twice as large as published seismic moments based on the inversion of p waveforms alone but close to the harvard cmt moment 4 7 10 18 nm we use sh waveforms in addition to the p waves used previously to determine an alternative seismic source mechanism sh waves constrain the depth to be shallower than solutions based on p waves alone agreeing with the depths from the interferometric inversion and resulting in a larger moment 3 1 0 4 10 18 nm than the previous bodywave estimates 2 2 1 10 18 nm the cmt moment reduces in magnitude to a similar size 3 3 10 18 nm if the centroid depth and fault dip are constrained to the values determined from bodywave modelling and interferometry thus the geodetic moment is 40 bigger than the moment determined from seismology

reply inferred subglacial meltwater origin of lakes on the southern border of the canadian shield paleozoic rocks form an escarpment up to 35 m high at the border with the frontenac axis of the canadian shield in southeastern ontario the escarpment which lies nearly transverse to the flow direction of pleistocene ice and subglacial meltwater in the region is cut by a series of deep channels locally incised into the bedrock at the escarpment a subbottom acoustic survey of two of these channels and mapping of a third partly flooded channel revealed the shape of the bedrock surface beneath the water and glacial and postglacial sediments of lakes now occupying the channels most cross sections show a smooth walled dominant depression eroded up to 100 m below the land surface nearby and flanked by one or more secondary depressions the pattern changes considerably in detail making secondary depressions especially difficult to trace along the length of the lake the pattern is similar to that of subglacial fluvial erosion marks more than three orders of magnitude smaller found in bedrock throughout

location and mechanism of the little skull mountain earthquake as constrained by satellite radar interferometry and seismic waveform modeling we use interferometric synthetic aperture radar insar and broadband seismic waveform data to estimate source parameters of the 29 june 1992 m s 5 4 little skull mountain lsm earthquake this event occurred within a geodetic network designed to measure the strain rate across the region around yucca mountain the lsm earthquake complicates interpretation of the existing gps and trilateration data as the earthquake magnitude is sufficiently small that seismic data do not tightly constrain the epicenter but large enough to potentially affect the geodetic observations we model the insar data using a finite dislocation in a layered elastic space we also invert regional seismic waveforms both alone and jointly with the insar data because of limitations in the existing data set insar data alone cannot determine the area of the fault plane independent of magnitude of slip nor the location of the fault plane independent of the earthquake mechanism our seismic waveform data tightly constrain the mechanism of the earthquake but not the location together the two complementary data types can be used to determine the mechanism and location but cannot distinguish between the two potential conjugate fault planes our preferred model has a moment of 3 2 10 17 n m m w 5 6 and predicts a line length change between the wahomie and mile geodetic benchmarks of 5 mm

a faulting model for the 1979 imperial valley earthquake by comparing synthetic particle velocities with the near source strong motion data we have constructed by trial and error a faulting model for the 1979 imperial valley earthquake the calculation of the synthetic seismograms takes into account the vertical inhomogeneity of the elastic parameters in the imperial valley and the spatial variation of the slip rate parameters on the fault plane the independent slip rate parameters are 1 the strike slip rate amplitude 2 the dip slip rate amplitude 3 the duration that slip rate is nonzero the rise time of the slip function and 4 the rupture time which determines when the slip rate is initiated our faulting model has the following principal features 1 faulting occurred on the imperial fault and on the brawley fault rupture on the brawley fault being triggered by rupture on the imperial fault 2 the imperial fault is a plane 35 km long and 13 km wide with a strike of 323 measured clockwise from north and a dip of 80 ne the brawley fault is a 10 km long and 8 km wide plane with a strike of 360 and a dip of 90 3 faulting on the imperial fault is primarily right lateral strike slip with a small component of normal dip slip in the sediments at its northern end the larger strike slip rates are generally confined between depths of 5 and 13 km with maximum values of about 1 0 m s the duration varies on the fault with a maximum of 1 9 s which is considerably shorter than the total time for the rupture to take place 4 the rupture velocity on the imperial fault is highly variable locally it exceeds the shear wave velocity and in one instance the compressional wave velocity the average rupture velocity though is less than the shear wave velocity 5 although the slip on the brawley fault contributes only about 4 of the total moment it greatly affects the ground motion at nearby stations 6 the total seismic moment is 6 7 1018 n m where the imperial fault contributes 6 4 1018 n m and the brawley fault contributes 2 7 1017 n m in the process of trying almost 300 faulting models we found that given the elastic parameters of the medium the synthetic seismograms were most sensitive to the specification of the rupture time although the slip rate amplitudes are linearly related to the data the rupture time and the duration are not the parameterization of the nonlinear variables has a strong effect on the generation of synthetic seismograms from a finite fault

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

comparison of various inversion techniques as applied to the determination of a geophysical deformation model for the 1983 borah peak earthquake abstract a number of techniques are employed to overcome nonuniqueness and instability inherent in linear inverse problems to test the factors that enter into the selection of an inversion technique for fault slip distribution we used a penalty function with smoothness pf s a damped least squares method dls damped least squares method with a positivity constraint dls p and a penalty function with smoothness and a positivity constraint pf s p for inverting the elevation changes for slip associated with the 1983 borah peak earthquake unlike solving an ill posed inverse problem using a gradient technique ward and barrientos 1986 we have restored the well posed character between the elevation changes and normal slip distribution studies showed that the constraints based on sound understanding of the physical nature of the problem are crucial in the derivation of a meaningful solution and dictates primarily the selection of a particular inversion technique all available geological and geophysical information were used to determine a geophysical deformation model for the earthquake it is suggested that the pf s p solution for a fault length of 75 km is the preferred model the long wavelength features in the estimated slip distribution are similar to those obtained by ward and barrientos 1986 whereas the shorter wavelength features differ between two solutions the fault dips 49 to the southwest the slipped zones deepen from the surface at the northwest to about 20 km downdip depth at the southeast the fault extends to the southeast beyond the epicenter of the mainshock it is also shown that only the long wavelength features of the slip distribution are well resolved the resolution is better at shallower levels than at deeper levels the resolution deteriorates when the deformation sources are away from the leveling lines smoothness constraints provide better resolution than damping does at depth the addition of a positivity constraint significantly improves the model resolution

tunnel channels and associated landforms south central ontario their implications for ice sheet hydrology the peterborough trenton drumlin field and associated meltwater erosion marks s forms were interpreted as the products of erosion by turbulent separated flows within a catastrophically released subglacial meltwater sheet the algonquin event recent theoretical modelling of ice sheet hydrology suggests progressive channelization of meltwater during the collapse of such a sheet inductive testing of this hypothesis using observations in south central ontario forms the crux of this paper a geometric model of the interaction of rough ice base and bed surfaces gives inferred meltwater flow patterns such a rough interactive geometry is suggested as the bed is drumlinized and flows responsible for drumlins may be expected to have eroded similar forms into the ice base three landforms in south central ontario namely tunnel channels megachannels and late stage sheet flow scours are described and interpreted as evidence of progressive channelization and flow diversion processes governed by the geometri

surface ruptures and building damage of the 2003 bam iran earthquake mapped by satellite synthetic aperture radar interferometric correlation 1 we use the interferometric correlation from envisat synthetic aperture radar sar images to map the details of the surface ruptures related to the 26 december 2003 earthquake that devastated bam iran the main strike slip fault rupture south of the city of bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram this also has a clear expression in the field because of the net extension across the fault just south of the city limits the surface strain becomes distributed over a width of about 500 m probably because of a thicker layer of soft sedimentary material another fault north of bam shows offset and low correlation over a wider zone in the interferograms but it has no discrete surface rupture possibly because of a net shortening across this fault taking the difference between the interferometric correlation for an interval including the earthquake and an interval before the earthquake separates the changes due to the earthquake from other effects in the partially vegetated city of bam we map the damage to buildings by measuring the change from high correlation to low correlation where buildings were destroyed by the earthquake

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