small scale deformations associated with the 1992 landers california earthquake mapped by synthetic aperture radar interferometry phase gradients the landers earthquake mw 7 3 occurred on june 28 1992 and ruptured nearly 100 km of previously mapped and unmapped faults in the mojave desert we use synthetic aperture radar interferometry insar to examine the cumulative surface deformation between april 24 and august 7 1992 in a 100 100 km region surrounding the northern portion of the earthquake rupture also we introduce a technique for manipulating sar interferograms to extract short wavelength displacement information this technique involves computation and subsequent combination of interferometric phase gradient maps the insar results show significant deformation signatures associated with faults fractures dry lake beds and mountainous regions within 75 100 km of the main rupture using the phase gradient method we are able to extract small scale deformation patterns near the main rupture many of the preexisting mapped faults within 50 km of the main rupture experienced triggered slip these include the old woman lenwood johnson valley west calico and calico faults the insar results also indicate right lateral offsets along secondary fractures trending n ne within the left lateral zone of shear between the main rupture and the johnson valley fault additionally there are interesting interferogram fringe signatures surrounding troy dry lake and coyote dry lake that are related to deformation of dry lake beds

dynamics of izmit earthquake postseismic deformation and loading of the duzce earthquake hypocenter we have developed dynamic finite element models of izmit earthquake postseismic deformation to evaluate whether this deformation is better explained by afterslip via either velocity strengthening frictional slip or linear viscous creep or by distributed linear viscoelastic relaxation of the lower crust we find that velocity strengthening frictional afterslip driven by coseismic shear stress loading can reproduce time dependent global positioning system data better than either linear viscous creep on a vertical shear zone below the rupture or lower crustal viscoelastic relaxation our best frictional afterslip model fits the main features of postseismic slip inversions in particular high slip patches at and below the hypocenter and on the western karadere segment and limited afterslip west of the hersek delta burgmann et al 2002 the model requires a weakly velocity strengthening fault that is either low effective normal stress in the slipping regions or a smaller value for the parameter describing rate dependence of friction a b than is indicated by laboratory experiments our best afterslip model suggests that the coulomb stress at the duzce hypocenter increased by 0 14 mpa 1 4 bars during the izmit earthquake assuming right lateral slip on a surface dipping 50 to the north and by another 0 1 mpa during the 87 days between the izmit and duzce earthquakes in the marmara sea region within about 160 km of the izmit earthquake rupture this model indicates that the coulomb stresses increased by 15 25 of the coseismic amount during the first 300 days after the earthquake three hundred days after the earthquake postseismic contributions to coulomb stressing rate on the maramara region faults had fallen to values equal to or less than the inferred secular stress accumulation rate our estimates of postseismic coulomb stress are highly model dependent in the marmara region the linear viscous shear zone and viscoelastic lower crust models predict greater postseismic coulomb stresses than the frictional afterslip model near field stress and fault zone rheology estimates are sensitive to the earth9s elastic structure when a layered elastic structure is incorporated in our model it yields a coulomb stress of 0 24 mpa at the duzce hypocenter significantly more than the 0 14 mpa estimated from the uniform elastic model because of the higher near field coseismic stresses the layered elastic model requires a higher value of velocity strengthening parameter a b a b times effective normal stress r to produce comparable postseismic slip a b is estimated at 0 4 and 0 2 mpa respectively for the layered and uniform elastic models these results highlight the importance of understanding the earth9s elastic structure and the mechanism for postseismic deformation if we wish to accurately model coseismic and postseismic crustal stresses

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

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

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

prograde and retrograde fluid flow during contact metamorphism of siliceous carbonate rocks from the ballachulish aureole scotland siliceous dolomites and limestones contain abundant retrograde minerals produced by hydration carbonation reactions as the aureole cooled marbles that contained periclase at the peak of metamorphism bear secondary brucite dolomite and serpentine forsterite dolomite marbles have retrograde tremolite and serpentine wollastonite limestones contain secondary calcite and quartz and wollastonite free limestones have retrograde tremolite secondary tremolite never appears in marbles where brucite has replaced periclase or in wollastonite bearing limestones a model for infiltration of siliceous carbonates by co2 h2o fluid that assumes a vertical upwardly directed flow b fluid flux proportional to cooling rate and c flow and reaction under conditions of local equilibrium between peak temperatures and 400 c reproduces the modes of altered carbonate rocks observed reaction textures and the incompatibility between tremolite and brucite and between tremolite and wollastonite except for samples from a dolomite xenolith retrograde time integrated flux recorded by reaction progress is on the order of 1000 mol fluid cm2 rock local focusing of flow near the contact is indicated by samples from the xenolith that record values an order of magnitude greater formation of periclase forsterite and wollastonite at the peak of metamorphism also required infiltration with prograde time integrated flux approximately 100 1000 mol cm2 the comparatively small values of prograde and retrograde time integrated flux are consistent with lack of stable isotope alteration of the carbonates and with the success of conductive thermal models in reproducing peak metamorphic temperatures recorded by mineral equilibria although isobaric univariant assemblages are ubiquitous in the carbonates most formed during retrograde metamorphism isobaric univariant assemblages observed in metacarbonates from contact aureoles may not record physical conditions at the peak of metamorphism as is commonly assumed

co seismic ruptures of the 12 may 2008 ms 8 0 wenchuan earthquake sichuan east west crustal shortening on oblique parallel thrusts along the eastern edge of tibet abstract the m s 8 0 wenchuan earthquake which devastated the mountainous western rim of the sichuan basin in central china produced a surface rupture over 200 km long with oblique thrust dextral slip and maximum scarp heights of 10 m it thus ranks as one of the world s largest continental mega thrust events in the last 150 yrs field investigation shows clear surface breaks along two of the main branches of the ne trending longmen shan thrust fault system the principal rupture on the nw dipping beichuan fault displays nearly equal amounts of thrust and right lateral slip basin ward of this rupture another continuous surface break is observed for over 70 km on the parallel more shallowly nw dipping pengguan fault slip on this latter fault was pure thrusting with a maximum scarp height of 3 5 m this is one of the very few reported instances of crustal scale co seismic slip partitioning on parallel thrusts this out of sequence event with distributed surface breaks on crustal mega thrusts highlights regional ew directed present day crustal shortening oblique to the longmen shan margin of tibet the long rupture and large offsets with strong horizontal shortening that characterize the wenchuan earthquake herald a re evaluation of tectonic models anticipating little or no active shortening of the upper crust along this edge of the plateau and require a re assessment of seismic hazard along potentially under rated active faults across the densely populated western sichuan basin and mountains

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

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

active tectonics of the beichuan and pengguan faults at the eastern margin of the tibetan plateau the steep high relief eastern margin of the tibetan plateau has undergone rapid cenozoic cooling and denudation yet shows little evidence for large magnitude shortening or accommodation generation in the foreland basin we address this paradox by using a variety of geomorphic observations to place constraints on the kinematics and slip rates of several large faults that parallel the plateau margin the beichuan and pengguan faults are active dominantly dextral slip structures that can be traced continuously for up to 200 km along the plateau margin both faults offset fluvial fill terraces that yield inheritance corrected cosmogenic 10be exposure ages of 15 kyr indicating latest pleistocene activity the pengguan fault appears to have been active in the holocene at two sites along strike latest quaternary apparent throw rates on both faults are variable along strike but are typically 1 mm yr 1 rates of strike slip displacement are likely to be several times higher probably 1 10 mm yr 1 but remain poorly constrained late quaternary folding and dextral strike slip has also occurred along the western margin of the sichuan basin particularly associated with the present day mountain front these observations support models for the formation and maintenance of the eastern plateau margin that do not involve major upper crustal shortening they also suggest that activity on the margin parallel faults in eastern tibet may represent a significant seismic hazard to the densely populated sichuan basin

fan delta uplift and mountain subsidence during the haiti 2010 earthquake the 2010 haiti earthquake was initially thought to have ruptured the enriquillo plantain garden fault but previously unrecognized faults were later implicated radar imaging of surface deformation caused by the earthquake reveals uplift of alluvial fans and subsidence of mountains consistent with reverse motion on a blind thrust fault

thermosphere global time response to geomagnetic storms caused by coronal mass ejections we investigate for the first time with a spatial superposed epoch analysis study the thermosphere global time response to 159 geomagnetic storms caused by coronal mass ejections cmes observed in the solar wind at earth s orbit during the period of september 2001 to september 2011 the thermosphere neutral mass density is obtained from the champ challenge mini satellite payload and grace gravity recovery climate experiment spacecraft all density measurements are intercalibrated against densities computed by the jacchia bowman 2008 empirical model under the regime of very low geomagnetic activity we explore both the effects of the pre cme shock impact on the thermosphere and of the storm main phase onset by taking their times of occurrence as zero epoch times cme impact and interplanetary magnetic field bz southward turning for each storm we find that the shock impact produces quick and transient responses at the two high latitude regions with minimal propagation toward lower latitudes in both cases thermosphere is heated in very high latitude regions within several minutes the bz southward turning of the storm onset has a fast heating manifestation at the two high latitude regions and it takes approximately 3 h for that heating to propagate down to equatorial latitudes and to globalize in the thermosphere this heating propagation is presumably accomplished at least in part with traveling atmospheric disturbances and complex meridional wind structures current models use longer lag times in computing thermosphere density dynamics during storms our results suggest that the thermosphere response time scales are shorter and should be accordingly adjusted in thermospheric empirical models

the 1999 hector mine earthquake southern california vector near field displacements from ers insar two components of fault slip are uniquely determined from two line of sight los radar interferograms by assuming that the fault normal component of displacement is zero we use this approach with ascending and descending interferograms from the ers satellites to estimate surface slip along the hector mine earthquake rupture the los displacement is determined by visually counting fringes to within 1 km of the outboard ruptures these los estimates and uncertainties are then transformed into strike and dip slip estimates and uncertainties the transformation is singular for a n s oriented fault and optimal for an e w oriented fault in contrast to our previous strike slip estimates which were based only on a descending interferogram we now find good agreement with the geological measurements except at the ends of the rupture the ascending interferogram reveals significant west side down dip slip 1 0 m which reduces the strike slip estimates by 1 to 2 m especially along the northern half of the rupture a spike in the strike slip displacement of 6 m is observed in central part of the rupture this large offset is confirmed by subpixel cross correlation of features in the before and after amplitude images in addition to strike slip and dip slip we identify uplift and subsidence along the fault related to the restraining and releasing bends in the fault trace respectively our main conclusion is that at least two look directions are required for accurate estimates of surface slip even along a pure strike slip fault models and results based only on a single look direction could have major errors our new estimates of strike slip and dip slip along the rupture provide a boundary condition for dislocation modeling a simple model which has uniform slip to a depth of 12 km shows good agreement with the observed ascending and descending interferograms

statistical comparison of the icme s geoeffectiveness of different types and different solar phases from 1995 to 2014 the geoeffectiveness of interplanetary coronal mass ejections icmes is an important issue in space weather research and forecasting based on the icme catalog that we recently established and the dst indices from the world data center we study and compare the geoeffectiveness of icmes of different in situ signatures and different solar phases from 1995 to 2014 according to different in situ signatures all icmes are divided into three types isolated icmes i icmes multiple icmes m icmes and shock embedded icmes s icmes resulting in a total of 363 group events the main findings of this work are as follows 1 fifty eight percent of icmes caused geomagnetic storms with dstmin 30 nt further large fraction 87 of intense geomagnetic storms are caused by icme groups and their sheath regions 2 numbers of icme groups and the probabilities of icme groups in causing geomagnetic storms varied in pace with the solar cycle meanwhile the icme groups and the probabilities of them in causing geomagnetic storms in solar cycle 24 are much lower than those in solar cycle 23 3 the maximum value of the intensity of the magnetic field b south component of the magnetic field bs and dawn dusk electric field vbs are well correlated with the intensity of the magnetic storms 4 shock embedded icmes have a high probability in causing geomagnetic storms especially intense geomagnetic storms 5 the compression of shock on the south component of magnetic field is an important factor to enhance the geoeffectiveness of s icmes structures

displacement field and slip distribution of the 2005 kashmir earthquake from sar imagery 1 the 8th october 2005 kashmir earthquake mw 7 6 involved primarily thrust motion on a ne dipping fault sub pixel correlation of envisat sar images gives the location of the 80 km long fault trace within 300 800 m and a 3d surface displacement field with a sub metric accuracy covering the whole epicentral area the slip distribution inverted using elastic dislocation models indicates that slip occurs mainly in the upper 10 km between the cities of muzaffarabad and balakot the rupture reached the surface in several places in the hanging wall horizontal motions show rotation from pure thrust to oblique right lateral motion that are not observed in the footwall a segmentation of the fault near muzaffarabad is also suggested north of the city of balakot slip decreases dramatically but a diffuse zone of mainly vertical surface displacements which could be post seismic exists further north where most of the aftershocks occur aligned along the nw se indus kohistan seismic zone

zagros phantom earthquakes reassessed the interplay of seismicity and deep salt flow in the simply folded belt unraveling the contributions of main shock slip aftershocks aseismic afterslip and postseismic relaxation to the deformation observed in earthquake sequences heightens our understanding of crustal rheology triggering phenomena and seismic hazard here we revisit two recent earthquakes in the zagros mountains iran which exhibited unusual and contentious aftereffects the mw 6 earthquakes at qeshm 2005 and fin 2006 are both associated with large interferometric synthetic aperture radar insar signals consistent with slip on steep reverse faults in carbonate rocks of the middle sedimentary cover but small aftershocks detected with local seismic networks were concentrated at significantly greater depths this discrepancy can be interpreted in one of two ways either 1 there is a genuine vertical separation between main shock and aftershocks reflecting a complex stress state near the basement cover interface or 2 the aftershocks delimit the main shock slip and the insar signals were caused by shallow updip afterslip phantom earthquakes with very similar magnitudes mechanisms and geographical positions as the original earthquakes here we show that main shock centroid depths obtained from body waveform modeling which in this instance is the only method that can reveal for certain the depth at which seismic slip was centered strongly support the first interpretation at qeshm microseismic aftershock depths are centered at the level of the hormuz formation an infracambrian sequence of intercalated evaporitic and nonevaporitic sediments these aftershocks may reflect the breaking up of harder hormuz sediments and adjacent strata as the salt flows in response to main shock strain at the base of the cover this work bolsters recent suggestions that most large earthquakes in the zagros are contained within carbonate rocks in the midlower sedimentary cover and that the crystalline basement shortens mostly aseismically

locations and types of ruptures involved in the 2008 sichuan earthquake inferred from sar image matching 1 we have detected detailed ground displacements in the proximity of the longmen shan fault zone lmsfz by applying a sar offset tracking method in the analysis of the 2008 sichuan earthquake an elevation dependent correction is indispensable for achieving sub meter accuracy a sharp displacement discontinuity with a relative motion of 1 2 m appears over a length of 200 km along the lmsfz which demonstrates that the main rupture has proceeded on the beichuan fault bf among several active faults composing the lmsfz and a new active fault is detected on the northeastward extension of the bf the rupture on the bf is characterized by a right lateral motion in the northeast while in the southwest an oblique right lateral thrust slip is suggested in contrast to the northeast where a major rupture proceeded on the bf only in the southwest multiple thrust ruptures have occurred in the southeastern foot of the pengguan massif

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

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

reconstructing movement history of frozen debris lobes in northern alaska using satellite radar interferometry abstract frozen debris lobes fdls are slow moving landslides along permafrost affected slopes and consist of soil rock organic debris and areas of massive infiltration ice based on their proximity to the adjacent infrastructure their size and their flow dynamics fdls represent potential geohazards eight fdls fdl a b c d 4 5 7 11 within the dalton highway corridor in the brooks range alaska usa are the subject of this paper we examined temporal and spatial variation of fdl displacement using medium resolution synthetic aperture radar sar images and differential sar interferometry dinsar techniques european remote sensing satellite 1 2 ers 1 2 and phased array type l band synthetic aperture radar palsar acquisitions were used to generate coherent interferograms to study the displacement history of fdls for 1995 1996 and 2006 2010 we conducted an initial assessment of the capability of satellite insar to monitor fdl movement depending on data resolution season and vegetation coverage which also helped us to select useful interferograms with multi temporal interferometric displacement maps we found that seven investigated fdls fdl 7 was excluded from this sub experiment due to limited data coverage demonstrated strong spatial and seasonal variations in their movement patterns with maximum displacement rates typically occurring in october and minimum displacement rates during february or march which is consistent with previously published field study results overall through this study we 1 delineated the active fdls during the winter period using a wrapped palsar interferogram 2 analyzed the spatial variation of the deformation field within each fdl body 3 modeled the seasonal changes of fdl deformation rates through the analysis of multi temporal ers tandem interferograms and 4 integrated insar derived deformation rates with those obtained through historical imagery analysis to determine long term deformation rates results from this study fill the gaps left in the historical imagery analysis and provide important seasonal and spatial deformation data which are essential in the development of a mitigation plan as these features approach infrastructure we also summarize our research experience studying these moving features using satellite radar interferometry and believe this can be useful for future studies of similar features

global positioning system measurements from eastern tibet and their implications for india eurasia intercontinental deformation we present and interpret global positioning system gps measurements of crustal motions for the period 1991 1998 for a network encompassing the eastern part of the tibetan plateau and its foreland relative to a eurasian frame defined by minimizing the velocities of 16 gps stations in europe central asia and siberia stations within all parts of the plateau foreland in south china move 6 10 mm yr east southeast indicating that the eastward movement within the plateau is part of a broader eastward movement that involves the plateau and its eastern and northern foreland north of the plateau foreland stations move northeastward at 10 mm yr indicating that the northern boundary of the deformation zone lies north of the plateau with this realization of a eurasian frame the velocity of the gps station at bangalore in southern india implies that the northward motion of india is 5 12 mm yr slower than that predicted from the nuvel 1a plate reconstruction viewed relative to the south china block stations of the northeast plateau bounded on the north by the qilian shan and the altyn tagh fault move nne to ne with velocities ranging from 19 mm yr within the plateau to 5 11 mm yr in its foreland the altyn tagh fault shows left lateral slip of 10 mm yr at 95 e and shortening across the fault of 5 mm yr stations south and west of the xianshuihe xiaojiang fault system define a crustal fragment rotating clockwise at 10 mm yr relative to the south china block around the eastern himalayan syntaxis the gps measurements indicate no significant shortening 3 mm yr within the longmen shan of the central eastern plateau and its adjacent foreland although the longmen shan rise over 6 km in 100 km horizontal distance geological studies indicate that the deformational field was established diachronously in late miocene to pliocene time was characterized by no east west shortening of tibetan crust and has an inhomogeneous style of deformation resulting from a balance of different tectonic processes

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

coseismic surface ruptures and crustal deformations of the 2008 wenchuan earthquake mw7 9 china 1 the irregularly distributed surface fault ruptures of the wenchuan earthquake spanned over 200 km along the longmen shan lms fault zone through field investigations we found over 10 coseismic surface ruptures with maximum vertical displacements of approximately 6 m on the yingxiu beichuan fault and 2 m on the guanxian anxian fault however the entire fault rupture movement was still not clearly understood since high topographic areas were inaccessible thus we used interferometric synthetic aperture radar insar satellite observations to capture whole coseismic surface ruptures and crustal deformations across the lms faults we created a novel bi fault slip model to invert fault slips using insar information which yielded that thrust fault slips were dominant at yingxiu houshenggou and bajiaomiao in the near epicenter segment while the dextral fault slips were dominant at pingtong and nanba along the northeast segment the combination of field investigations and simulations suggested that the two coseismic fault zones ruptured with an irregular surface distribution accompanied by crustal deformations

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

scansar to stripmap mode interferometry processing using envisat asar data interferometric synthetic aperture radar insar images of geophysical events such as preeruptive volcano deformation or interseismic strain accumulation are often limited by phase distortions from the superimposed atmospheric signature additionally the approximate monthly repeat cycle of many radar satellites cannot accurately capture rapidly time varying processes the scanning synthetic aperture radar scansar mode of the envisat asar instrument permits more frequent revisits of a given area potentially overcoming both of these limitations in particular stripmap mode to scansar images provide a denser time series of interferograms than is possible with conventional stripmap to stripmap mode insar we present images of envisat asar data acquired over hawaii in which data acquired roughly weekly in scansar mode are combined with envisat asar conventional stripmap mode data to form interferograms at a much denser temporal spacing the burst nature of scansar data requires a new processing method to form the interferograms we use traditional matched filtering for the range compression for the azimuth processing we compute the stripmap mode data on the scansar sampling grid using a variation consisting of different reference functions of lanari s modified specan algorithm that is itself an adaptation of the chirp z transform to readjust the azimuth pulse spacing the resulting interferograms faithfully reflect the phase of conventional interferograms but exhibit fewer looks and coarser resolution than those produced by fully stripmap mode data for many problems temporal density of the deformation observations is paramount and the time series analysis and temporal averaging that were made possible using scansar interferograms far outweigh the loss in looks and resolution

accuracy and resolution of alos interferometry vector deformation maps of the father s day intrusion at kilauea we assess the spatial resolution and phase noise of interferograms made from l band advanced land observing satellite alos synthetic aperture radar sar data and compare these results with corresponding c band measurements from european space agency remote sensing satellite ers based on cross spectral analysis of phase gradients we find that the spatial resolution of alos interferograms is 1 3times better than ers interferograms the phase noise of alos i e line of sight precision in the 100 5000 m wavelength band is 1 6times worse than ers 3 3 mm versus 2 1 mm in both cases the largest source of error is tropospheric phase delay vector deformation maps associated with the june 17 2007 father s day intrusion along the east rift zone of the kilauea volcano were recovered using just four alos sar images from two look directions comparisons with deformation vectors from 19 continuous gps sites show rms line of site precision of 14 mm and rms azimuth precision flight direction of 71 mm this azimuth precision is at least 4times better than the corresponding measurements made at c band phase coherence is high even in heavily vegetated areas in agreement with previous results this improved coherence combined with similar or better accuracy and resolution suggests that l band alos will outperform c band ers in the recovery of slow crustal deformation

frictional afterslip following the 2005 nias simeulue earthquake sumatra continuously recording global positioning system stations near the 28 march 2005 rupture of the sunda megathrust moment magnitude m w 8 7 show that the earthquake triggered aseismic frictional afterslip on the subduction megathrust with a major fraction of this slip in the up dip direction from the main rupture eleven months after the main shock afterslip continues at rates several times the average interseismic rate resulting in deformation equivalent to at least a m w 8 2 earthquake in general along strike variations in frictional behavior appear to persist over multiple earthquake cycles aftershocks cluster along the boundary between the region of coseismic slip and the up dip creeping zone we observe that the cumulative number of aftershocks increases linearly with postseismic displacements this finding suggests that the temporal evolution of aftershocks is governed by afterslip

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

solar and interplanetary sources of major geomagnetic storms dst 100 nt during 1996 2005 1 we present the results of an investigation of the sequence of events from the sun to the earth that ultimately led to the 88 major geomagnetic storms defined by minimum dst 100 nt that occurred during 1996 2005 the results are achieved through cooperative efforts that originated at the living with a star lws coordinated dataanalysis workshop cdaw held at george mason university in march 2005 on the basis of careful examination of the complete array of solar and in situ solar wind observations we have identified and characterized for each major geomagnetic storm the overall solar interplanetary solar ip source type the time velocity and angular width of the source coronal mass ejection cme the type and heliographic location of the solar source region the structure of the transient solar wind flow with the storm driving component specified the arrival time of shock disturbance and the start and ending times of the corresponding ip cme icme the storm driving component which possesses a prolonged and enhanced southward magnetic field bs may be an icme the sheath of shocked plasma sh upstream of an icme a corotating interaction region cir or a combination of these structures we classify the solar ip sources into three broad types 1 s type in which the storm is associated with a single icme and a single cme at the sun 2 m type in which the storm is associated with a complex solar wind flow produced by multiple interacting icmes arising from multiple halo cmes launched from the sun in a short period 3 c type in which the storm is associated with a cir formed at the leading edge of a high speed stream originating from a solar coronal hole ch for the 88 major storms the s type m type and c type events number 53 60 24 27 and 11 13 respectively for the 85 events for which the surface source regions could be investigated 54 63 of the storms originated in solar active regions 11 13 in quiet sun regions associated with quiescent filaments or filament channels and 11 13 were associated with coronal holes remarkably nine 11 cme driven events showed no sign of eruptive features on the surface or in the low corona e g no flare no coronal dimming and no loop arcade etc even though all the available solar observations in a suitable time period were carefully examined thus while it is generally true that a major geomagnetic storm is more likely to be driven by a frontside fast halo cme associated with a major flare our study indicates a broad distribution of source properties the implications of the results for space weather forecasting are briefly discussed

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

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

mobility of continental mantle evidence from postseismic geodetic observations following the 1992 landers earthquake the crust around the rupture zone of the 1992 landers earthquake has continued to deform in the years following the earthquake at rates 3 times greater than pre earthquake rates we use a combination of global positioning system gps and synthetic aperture radar insar data collected during a 3 year epoch following the earthquake in order to investigate postseismic mechanisms responsible for the high transient velocities in order to maximize the potential signal from viscoelastic relaxation we evaluate and model postseismic relaxation following the first few months of documented accelerated deformation the combination of gps and insar data allows us to establish viscoelastic relaxation of the lower crust and upper mantle as the dominant postseismic process and to discriminate among possible viscoelastic models the data particularly require the presence of a highly ductile uppermost mantle beneath the central mojave domain with temperature between the wet and dry basalt solidus this is consistent with independent seismic and geochemical inferences of a regionally warm uppermost mantle further consideration of seismic velocity variations in conjunction with faulting patterns within the mojave desert suggests that the primary faulting characteristics of the mojave desert namely the pervasive late cenozoic deformation within the eastern california shear zone versus the near absence of faults in the western mojave domain are controlled by the rheology of the uppermost mantle

which fault segments ruptured in the 2008 wenchuan earthquake and which did not new evidence from near fault 3d surface displacements derived from sar image offsets the 2008 m w 7 9 wenchuan earthquake ruptured a complex thrust faulting system at the eastern edge of the tibetan plateau and west of sichuan basin though the earthquake has been extensively studied several details about the earthquake such as which fault segments were activated in the earthquake are still not clear this is in part due to difficult field access to the fault zone and in part due to limited near fault observations in interferometric synthetic aperture radar insar observations because of decorrelation in this study we address this problem by estimating sar image offsets that provide near fault ground displacement information and exhibit clear displacement discontinuities across activated fault segments we begin by reanalyzing the coseismic insar observations of the earthquake and then mostly eliminate the strong ionospheric signals that were plaguing previous studies by using additional postevent images we also estimate the sar image offsets and use their results to retrieve the full 3d coseismic surface displacement field the coseismic deformation from the insar and image offset measurements are compared with both global positioning system and field observations the results indicate that our observations provide significantly better information than previous insar studies that were affected by ionospheric disturbances we use the results to present details of the surface faulting offsets along the beichuan fault from the southwest to the northeast and find that there is an obvious right lateral strike slip component as well as thrust faulting along the southern beichuan fault in yingxiu county which was strongly underestimated in earlier studies based on the results we provide new evidence to show that the qingchuan fault was not ruptured in the 2008 wenchuan earthquake a topic debated in field observation studies but show instead that surface faulting occurred on a northward extension of the beichuan fault during or immediately following the mainshock electronic supplement 1 parallel ascending orbit track coseismic deformation 1 http www bssaonline org lookup suppl doi 10 1785 0120160126 dc1

coseismic radiation of the 2008 m w 7 9 wenchuan earthquake and its relationship to fault complexities the long rupture length and complex fault geometries of the 2008 mw 7 9 wenchuan earthquake offer a great opportunity to investigate the relationship between coseismic radiation and fault complexities in this study we first improved the compressive sensing back projection method cs bp with window time adjustment and parallel computation to enhance its spatial temporal resolution and computational efficiency then we applied the cs bp to invert for the coseismic radiation of the wenchuan earthquake in multiple frequency bands our results show that the coseismic radiation of the wenchuan earthquake is frequency dependent and strongly associated with the fault geometries low frequency radiation sources are concentrated on smooth fault segments with large coseismic slip while higher frequency sources are mainly related to fault complexities e g xiaoyudong fault gaochuan fault bend leigu fault bend and nanba fault step over an acceleration of rupture speed from 1 5 to 3 0 km s is also observed the near xiaoyudong fault where strong high frequency energies were radiated finally we discuss the role of rupture speed in mediating the relationship between coseismic radiation and fault complexities on one hand sudden changes of rupture speeds contribute to strong high frequency radiation on the other hand fault complexities can also strongly affect the rupture speed a sudden break of a large asperity is able to propel the acceleration while rupture front may decelerate when it jumps across geometric barriers

validation of linearity assumptions for using tsunami waveforms in joint inversion of kinematic rupture models application to the 2010 mentawai mw 7 8 tsunami earthquake tsunami observations have particular importance for resolving shallow offshore slip in finite fault rupture model inversions for large subduction zone earthquakes however validations of amplitude linearity and choice of subfault discretization of tsunami green s functions are essential when inverting tsunami waveforms we explore such validations using four tsunami recordings of the 25 october 2010 mentawai m w 7 8 tsunami earthquake jointly inverted with teleseismic body waves and 1 hz gps high rate gps observations the tsunami observations include near field and far field deep water recordings as well as coastal and island tide gauge recordings a nonlinear dispersive modeling code neowave is used to construct tsunami green s functions from seafloor excitation for the linear inversions along with performing full scale calculations of the tsunami for the inverted models we explore linearity and finiteness effects with respect to slip magnitude variable rake determination and subfault dimensions the linearity assumption is generally robust for the deep water recordings and wave dispersion from seafloor excitation is important for accurate description of near field green s functions breakdown of linearity produces substantial misfits for short wavelength signals in tide gauge recordings with large wave heights including the tsunami observations in joint inversions provides improved resolution of near trench slip compared with inversions of only seismic and geodetic data two rupture models with fine grid 15 km and coarse grid 30 km spacing are inverted for the mentawai event stronger regularization is required for the fine model representation both models indicate a shallow concentration of large slip near the trench with peak slip of 15 m fully nonlinear forward modeling of tsunami waveforms confirms the validity of these two models for matching the tsunami recordings along with the other data

the 2005 mw 7 6 kashmir earthquake sub pixel correlation of aster images and seismic waveforms analysis we analyze the m w 7 6 kashmir earthquake of october 8 2005 using sub pixel correlation of aster images to measure ground deformation and modeling seismic waveforms the surface rupture is continuous over a distance of 75 km and cuts across the hazara syntaxis reactivating the tanda and the muzaffarabad faults north of muzaffarabad the surface rupture coincides approximately with the mbt on the southwestern flank of the syntaxis although the two faults have opposite dip angles the rupture terminates abruptly at the hairpin turn of the mbt showing a strong structural control the fault offset is 4 m on average and peaks to 7 m northwest of muzaffarabad the rupture lasted about 25 s and propagated updip and bi laterally 2 km s with a rise time of 2 5 s the shallowness and compactness of the rupture both in time and space provide an explanation for the intensity of destructions this kind of analysis could be achieved as soon as a post earthquake image is available and would provide key information for early assessment of damages the study sheds some light on seismic hazard in the himalaya and raises concern regarding the possibility of a repetition of the 1555 event which presumably ruptured the himalayan front south of the kashmir basin and may have reached a magnitude m w 8

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

three dimensional compressional wavespeed model earthquake relocations and focal mechanisms for the parkfield california region we present a new three dimensional 3d compressional wavespeed v p model for the parkfield region taking advantage of the recent seismicity associated with the 2003 san simeon and 2004 parkfield earthquake sequences to provide increased model resolution compared to the work of eberhart phillips and michael 1993 epm93 taking the epm93 3d model as our starting model we invert the arrival time data from about 2100 earthquakes and 250 shots recorded on both permanent network and temporary stations in a region 130 km northeast southwest by 120 km northwest southeast we include catalog picks and cross correlation and catalog differential times in the inversion using the double difference tomography method of zhang and thurber 2003 the principal v p features reported by epm93 and michelini and mcevilly 1991 are recovered but with locally improved resolution along the san andreas fault saf and near the active source profiles we image the previously identified strong wavespeed contrast faster on the southwest side across most of the length of the saf and we also improve the image of a high v p body on the northeast side of the fault reported by epm93 this narrow body is at about 5 to 12 km depth and extends approximately from the locked section of the saf to the town of parkfield the footwall of the thrust fault responsible for the 1983 coalinga earthquake is imaged as a northeast dipping high wavespeed body in between relatively low wavespeeds 5 km sec extend to as much as 10 km depth we use this model to derive absolute locations for about 16 000 earthquakes from 1966 to 2005 and high precision double difference locations for 9 000 earthquakes from 1984 to 2005 and also to determine focal mechanisms for 446 earthquakes these earthquake locations and mechanisms show that the seismogenic fault is a simple planar structure the aftershock sequence of the 2004 mainshock concentrates into the same structures defined by the pre 2004 seismicity confirming earlier observations waldhauser et al 2004 that the seismicity pattern at parkfield is long lived and persists through multiple cycles of mainshocks online material 3d v p model and earthquake relocations

postseismic deformation due to the mw 6 0 2004 parkfield earthquake stress driven creep on a fault with spatially variable rate and state friction parameters 1 we investigate the coseismic and postseismic deformation due to the m w 6 0 2004 parkfield california earthquake we produce coseismic and postseismic slip models by inverting data from an array of 14 continuous gps stations from the scign network kinematic inversions of postseismic gps data over a time period of 3 years show that afterslip occurred in areas of low seismicity and low coseismic slip predominantly at a depth of 5 km inversions suggest that coseismic stress increases were relaxed by predominantly aseismic afterslip on a fault plane the kinetics of afterslip is consistent with a velocity strengthening friction generalized to include the case of infinitesimal velocities we performed simulations of stress driven creep using a numerical model that evaluates the time dependent deformation due to coseismic stress changes in a viscoelastoplastic half space starting with a coseismic slip distribution we compute the time dependent evolution of afterslip on a fault plane and the associated displacements at the gps stations data are best explained by a rate strengthening model with frictional parameter a b 7 x 10 3 at a high end of values observed in laboratory experiments we also find that the geodetic moment due to creep is a factor of 100 greater than the cumulative seismic moment of aftershocks the rate of aftershocks in the top 10 km of the seismogenic zone mirrors the kinetics of afterslip suggesting that postearthquake seismicity is governed by loading from the nearby aseismic creep the san andreas fault around parkfield is deduced to have large along strike variations in rate and state frictional properties velocity strengthening areas may be responsible for the separation of the coseismic slip in two distinct asperities and for the ongoing aseismic creep occurring between the velocity weakening patches after the 2004 rupture

evidence of sudden rupture of a large asperity during the 2008 mw7 9 wenchuan earthquake based on strong motion analysis 1 we investigate the rupture process of the 12 may 2008 wenchuan earthquake using the records of 26 strong motion stations located 20 120 km from the seismic fault and with a good azimuthal coverage the wave velocity model required to conduct this analysis has been validated against aftershocks for which the point source hypothesis is a very good approximation the inversion of the main shock rupture process confirms the slip distribution and the average rupture velocity 3 km s previously determined however a very peculiar behavior is clearly resolved by the extensive data set used in this study the major slip area of the wenchuan earthquake located at 20 50 km north east of the epicenter is shown to break almost simultaneously 25 s after earthquake initiation this implies that slip in this part of the fault cannot be understood by simple stress release at the rupture front a more likely interpretation is the presence of a strong asperity which could break only when it was completely surrounded by stress increase resulting in a delayed but brutal rupture

a three step maximum a posteriori probability method for insar data inversion of coseismic rupture with application to the 14 april 2010 mw 6 9 yushu china earthquake 1 we develop a three step maximum a posteriori probability method for coseismic rupture inversion which aims at maximizing the a posterior probability density function pdf of elastic deformation solutions of earthquake rupture the method originates from the fully bayesian inversion and mixed linear nonlinear bayesian inversion methods and shares the same posterior pdf with them while overcoming difficulties with convergence when large numbers of low quality data are used and greatly improving the convergence rate using optimization procedures a highly efficient global optimization algorithm adaptive simulated annealing is used to search for the maximum of a posterior pdf mode in statistics in the first step the second step inversion approaches the true solution further using the monte carlo inversion technique with positivity constraints with all parameters obtained from the first step as the initial solution then slip artifacts are eliminated from slip models in the third step using the same procedure of the second step with fixed fault geometry parameters we first design a fault model with 45 dip angle and oblique slip and produce corresponding synthetic interferometric synthetic aperture radar insar data sets to validate the reliability and efficiency of the new method we then apply this method to insar data inversion for the coseismic slip distribution of the 14 april 2010 mw 6 9 yushu china earthquake our preferred slip model is composed of three segments with most of the slip occurring within 15 km depth and the maximum slip reaches 1 38 m at the surface the seismic moment released is estimated to be 2 32e 19 nm consistent with the seismic estimate of 2 50e 19 nm

stress evolution before and after the 2008 wenchuan china earthquake abstract we examine the distribution of coulomb stress before and following the m 7 9 wenchuan earthquake and model the time dependent components of the stress field into the future our modelling shows that the combined coseismic plus postseismic viscoelastic stress change due to the preceding large events m 6 7 at the hypocentral area of the wenchuan earthquake is negative which may have led to a delay on its occurrence between 16 and 95 yr depending on the rake of the rupture on the other hand coseismic stress modelling of the wenchuan earthquake shows strong interaction particularly with the faults close to its sw and ne ends such interactions have previously been shown to trigger further large earthquakes in addition redistribution of stresses due to continuing postseismic deformation will potentially increase the stress levels not only on these faults but also on the distant faults such as the xianshuihe kunlun and tazang faults postseismic viscoelastic stress load on these distant faults over the next 22 yr since the earthquake could be up to 2 5 times larger than that of the coseismic stress increase alone this would potentially advance these faults in their seismic cycle and thereby encourage future earthquakes resulting in clustering of large earthquakes in the region this behaviour however strongly depends on the stage that these faults are in their seismic cycle which is not known currently given the high density of population in the area with several cities chengdu guangyuan and hanzhong of more than 1 million inhabitants our results indicate a need for detailed paleoseismic studies to help elucidate the state of the stressed faults

modeling afterslip and aftershocks following the 1992 landers earthquake one way to probe the rheology of the lithosphere and fault zones is to analyze the temporal evolution of deformation following a large earthquake in such a case the lithosphere responds to a known stress change that can be assessed from earthquake slip models constrained from seismology and geodesy here we model the postseismic response of a fault zone that is assumed to obey a rate strengthening rheology where the frictional stress varies as a ln e e being the deformation rate and a 0 a rheological parameter the model is simple enough that these parameters can be estimated by inversion of postseismic geodetic data we apply this approach to the analysis of geodetic displacements following the m w 7 3 1992 landers earthquake the model adjusts well the measured displacements and implies a 0 47 0 53 mpa in addition we show that aftershocks and afterslip follow the same temporal evolution and that the spatiotemporal distribution of aftershocks is consistent with the idea that they are driven by reloading of the seismogenic zone resulting from frictional afterslip

distribution of active rock uplift along the eastern margin of the tibetan plateau inferences from bedrock channel longitudinal profiles 1 current models of long term river incision into bedrock suggest that the local rate of differential rock uplift should exert a primary control on the gradient of channel longitudinal profiles however discrimination of this effect from the influence of variations in substrate erodibility sediment flux precipitation and transient changes in profile shape has proved difficult in practice here we investigate the controls on the spatial distribution of bedrock channel gradients adjacent to the sichuan basin in an effort to assess the degree and nature of active deformation along this margin of the tibetan plateau analysis of river longitudinal profiles utilizing a channel steepness index a measure of profile gradient normalized for drainage area reveals a zone of anomalously steep channels adjacent to the topographic front of the plateau margin channel profiles are systematically less steep in their headwater reaches on the plateau and in their lower reaches east of the plateau margin comparison of steepness indices to mapped lithologic variations reveals that lithology has only a limited influence on channel gradient in this field area we observe no systematic relationship between steepness indices and upstream drainage area channels of all size are steeper near the plateau margin we argue that these systematic changes are not readily explained as a consequence of increased sediment flux or of orographic precipitation we are led to conclude that steep channel profiles along the topographic front of the plateau reflect active differential rock uplift between this region and the foreland

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