crustal subsidence observed by grace after the 2013 okhotsk deep focus earthquake coseismic gravity changes stem from 1 vertical deformation of layer boundaries with density contrast i e surface and moho and 2 density changes of rocks at depth they have been observed in earthquakes with mw exceeding 8 5 by gravity recovery and climate experiment grace satellites but those of m8 class earthquakes have never been detected clearly here we report coseismic gravity change of the 24 may 2013 okhotsk deep earthquake mw8 3 smaller than the detection threshold in shallow thrust faulting factor 2 is dominant while factor 1 remains secondary due to poor spatial resolution of grace in the 2013 okhotsk earthquake however factor 2 is insignificant because they occur at depth exceeding 600 km on the other hand factor 1 becomes dominant because the centers of uplift and subsidence are well separated and grace can resolve them this enables grace to map vertical ground movements of deep earthquakes over both land and ocean

coseismic offsets due to the 11 april 2012 indian ocean earthquakes mw 8 6 and 8 2 derived from gps measurements 1 the 11 april 2012 earthquake mw 8 6 in the indian ocean about 100 km west off the sumatra subduction zone is the largest intraplate strike slip earthquake in the known history two hours later it triggered another great earthquake of mw 8 2 in its vicinity the earthquakes reflect the internal deformation of the diffused plate boundary between india and australia caused by the differential plate motion between them the slip occurred on conjugate planes and the presence of some of them has been reported from the swath bathymetry and satellite magnetic anomalies we estimate coseismic offsets due to these earthquakes at continuous gps sites in the andaman nicobar region and at other international gnss service igs sites around the earthquakes source region the sites on the andaman islands which are about 900 1200 km to the north of the earthquake epicenters experienced predominantly southward coseismic offset of up to 3 cm the nearest site campbell bay on great nicobar island about 500 km to the north of the earthquake documented an ese offset of about 4 cm the coseismic offsets are consistent with the finite fault slip models derived from back projection of the seismic waves recorded by the global networks

rupture kinematics of the 2005 mw 8 6 nias simeulue earthquake from the joint inversion of seismic and geodetic data the 2005 mw 8 6 nias simeulue earthquake was caused by rupture of a portion of the sunda megathrust offshore northern sumatra this event occurred within an array of continuous global positioning system gps stations and produced measurable vertical displacement of the fringing coral reefs above the fault rupture thus this earthquake provides a unique opportunity to assess the source character istics of a megathrust event from the joint analysis of seismic data and near field static co seismic displacements based on the excitation of the normal mode data and geodetic data we put relatively tight constraints on the seismic moment and the fault dip where the dip is determined to be 8 to 10 with corresponding moments of 1 24 10 22 to 1 00 10 22 n m respectively the geodetic constraints on slip distribution help to eliminate the trade off between rupture velocity and slip kine matics source models obtained from the inversion of various combinations of the teleseismic body waves and geodetic data are evaluated by comparing predicted and observed long period seismic waveforms 100 500 sec our results indicate a rela tively slow average rupture velocity of 1 5 to 2 5 km sec and long average rise time of up to 20 sec the earthquake nucleated between two separate slip patches one beneath nias and the other beneath simeulue island the gap between the two patches and the hypocentral location appears to be coincident with a local geological disrup tion of the forearc coseismic slip clearly tapers to zero before it reaches the trench probably because the rupture propagation was inhibited when it reached the accre tionary prism using the models from joint inversions we estimate the peak ground velocity on nias island to be about 30 cm sec an order of magnitude slower than for thrust events in continental areas this study emphasizes the importance of util izing multiple datasets in imaging seismic ruptures

observing coseismic gravity change from the japan tohoku oki 2011 earthquake with goce gravity gradiometry the japan tohoku oki earthquake 9 0 mw of 11 march 2011 has left signatures in the earth s gravity field that are detectable by data of the gravity field recovery and climate experiment grace mission because the european space agency s esa satellite gravity mission gravity field and steady state ocean circulation explorer goce launched in 2009 aims at high spatial resolution its measurements could complement the grace information on coseismic gravity changes although time variable gravity was not foreseen as goal of the goce mission we modeled the coseismic earthquake geoid signal and converted this signal to vertical gravity gradients at goce satellite altitude we combined the single gradient observations in a novel way reducing the noise level required to detect the coseismic gravity change subtracted a global gravity model and applied tailored outlier detection to the resulting gradient residuals furthermore the measured gradients were along track filtered using different gradient bandwidths where in the space domain gaussian smoothing has been applied one year periods before and after earthquake occurrence have been compared with the modeled gradients the comparison reveals that the earthquake signal is well above the accuracy of the vertical gravity gradients at orbital height moreover the obtained signal from goce shows a 1 3 times higher amplitude compared with the modeled signal besides the statistical significance of the obtained signal it has a high spatial correlation of 0 7 with the forward modeled signal we conclude therefore that the coseismic gravity change of the japan tohoku oki earthquake left a statistically significant signal in the goce measured gravity gradients

interhemispheric air temperature phase relationships in the nonlinear dansgaard oeschger oscillation it has previously been suggested that the southern ocean might act as a thermal reservoir in mediating the relationship between the northern and southern hemisphere air temperature signals during a dansgaard oeschger cycle on the basis of a climate model based analysis we demonstrate on the contrary that it is equatorial and subtropical north atlantic thermocline waters that act so as to integrate and damp the northern hemisphere signal to fix the amplitude and phase of the southern hemisphere counterpart to the more intense north atlantic component of the oscillation the dynamics of the southern ocean component of the atlantic meridional overturning circulation are critical in explaining the evolution of the interhemispheric temperature phase relationships european project for ice coring in antarctica dronning maud land inferred air temperature variations are in phase with sea surface temperatures north of the antarctic sea ice edge suggesting that it is via a fast atmospheric pathway that this temperature signal is transmitted into the antarctic ice core record

a source model for the great 2011 tohoku earthquake mw 9 1 from inversion of grace gravity data abstract the co seismic slip distribution of the 2011 tohoku megathrust earthquake is constrained from geoforschungszentrum gfz gravity recovery and climate experiment grace level 2 data time series and our self gravitating compressible 1 d earth model after spatial localization of space gravity data in the surrounding of the u s geological survey usgs epicenter by means of orthogonal slepian functions we estimate the long wavelength co seismic gravity signature the pattern is bipolar the positive pole off shore in the pacific ocean 3 6 gal and the negative pole in the northern japan and japan sea 8 6 gal inversion of the grace data resolves average features of finite fault models the total seismic moment 5 3 1 10 22 nm corresponding to m w 9 1 in agreement with the centroid moment tensor solution the rake angle 87 9 and the mean position of the slip distribution on the fault plane we obtain that the mean depth of the rupture is 17 1 5 km just below the moho discontinuity although we cannot exclude that the rupture also extended to shallower crustal layers and deeper within the lithospheric mantle due to the poor resolution of the along dip dimension of the fault

crustal dilatation observed by grace after the 2004 sumatra andaman earthquake we report the detection of an earthquake by a space based measurement the gravity recovery and climate experiment grace satellites observed a 15 microgalileo gravity change induced by the great december 2004 sumatra andaman earthquake coseismic deformation produces sudden changes in the gravity field by vertical displacement of earth s layered density structure and by changing the densities of the crust and mantle grace s sensitivity to the long spatial wavelength of gravity changes resulted in roughly equal contributions of vertical displacement and dilatation effects in the gravity measurements the grace observations provide evidence of crustal dilatation resulting from an undersea earthquake

coseismic gravity changes of the 2010 earthquake in central chile from satellite gravimetry 1 the first map of coseismic changes in gravity and geoid height has been drawn using the data from the gravity recovery and climate experiment grace satellites for the 2004 sumatra andaman earthquake here we present the second case of coseismic gravity change observation by satellite gravimetry i e the change caused by an interplate thrust earthquake that occurred on 27 february 2010 in central chile mw 8 8 gravity showed a negative jump with the largest drop of 5 gal on the back arc side the observed changes agree with those calculated assuming the realistic earth and fault parameters inferred from coseismic displacements of global positioning system gps stations gravity in this area shows large seasonal and inter annual variability and postseismic gravity changes could be isolated only by carefully removing hydrological signals

grace measurements of mass variability in the earth system monthly gravity field estimates made by the twin gravity recovery and climate experiment grace satellites have a geoid height accuracy of 2 to 3 millimeters at a spatial resolution as small as 400 kilometers the annual cycle in the geoid variations up to 10 millimeters in some regions peaked predominantly in the spring and fall seasons geoid variations observed over south america that can be largely attributed to surface water and groundwater changes show a clear separation between the large amazon watershed and the smaller watersheds to the north such observations will help hydrologists to connect processes at traditional length scales tens of kilometers or less to those at regional and global scales

the nicoya convergent margin a region of exceptionally low heat flow over 100 measurements of seafloor heat flow reveal that the accretionary complex adjacent to the nicoya peninsula is characterized by remarkably low heat flow values over the accretionary prism average 28 mw m and values in the trench and the ocean crust seaward of the trench average 14 mw m we attribute the low heat flow to effective hydrothermal cooling of the upper crust on the subducting plate and suggest that extensional faults created by flexure of the lithosphere enhance hydrothermal circulation thermal models show that subduction of low temperature crust combined with significant frictional heating at the decollement can explain the low and uniform heat flow disparity between heat flow values observed on the lower trench slope with model results suggests upward advection of heat by porewater flux through broadly distributed conduits

implications of the 26 december 2004 sumatra andaman earthquake on tsunami forecast and assessment models for great subduction zone earthquakes results from different tsunami forecasting and hazard assessment mod els are compared with observed tsunami wave heights from the 26 december 2004 indian ocean tsunami forecast models are based on initial earthquake information and are used to estimate tsunami wave heights during propagation an empirical forecast relationship based only on seismic moment provides a close estimate to the observed mean regional and maximum local tsunami runup heights for the 2004 indian ocean tsunami but underestimates mean regional tsunami heights at azimuths in line with the tsunami beaming pattern e g sri lanka thailand standard forecast models developed from subfault discretization of earthquake rupture in which deep ocean sea level observations are used to constrain slip are also tested forecast models of this type use tsunami time series measurements at points in the deep ocean as a proxy for the 2004 indian ocean tsunami a transect of deep ocean tsunami amplitudes recorded by satellite altimetry is used to constrain slip along four subfaults of the m 9 sumatra andaman earthquake this proxy model performs well in comparison to observed tsunami wave heights travel times and inundation patterns at banda aceh hypothetical tsunami hazard assessments models based on end member estimates for average slip and rupture length m w 9 0 9 3 are compared with tsunami observations using average slip low end member and rupture length high end member m w 9 14 consistent with many seismic geodetic and tsunami inversions adequately estimates tsunami runup in most regions except the extreme runup in the western aceh province the high slip that occurred in the southern part of the rupture zone linked to runup in this location is a larger fluctuation than expected from standard stochastic slip models in addition excess moment release 9 deduced from geodetic studies in comparison to seismic moment estimates may gen erate additional tsunami energy if the exponential time constant of slip is less than approximately 1 hr overall there is significant variation in assessed runup heights caused by quantifiable uncertainty in both first order source parameters e g rupture length slip length scaling and spatiotemporal complexity of earthquake rupture

en echelon and orthogonal fault ruptures of the 11 april 2012 great intraplate earthquakes the magnitude 8 7 earthquake that occurred off the coast of the sumatra subduction zone on 11 april 2012 is shown to have had an extraordinarily complex four fault rupture these great ruptures represent large lithospheric deformation that may eventually lead to a localized boundary between the indian and australian plates on 11 april 2012 two of the largest strike slip earthquakes ever recorded at magnitudes of 8 7 and 8 2 occurred in the northeastern indian ocean a few hundred kilometres off the coast of sumatra three groups now report the analysis of seismic data from the days and months before and after these events as well as the events themselves matthias delescluse and co authors show that these earthquakes are part of the ongoing boost of intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes they conclude that the australian plate driven by slab pull forces at the sunda trench is gradually detaching from the indian plate han yue and colleagues show that the 11 april event involved a complex four fault rupture lasting several minutes followed two hours later by a magnitude 8 2 aftershock these great ruptures on a lattice of strike slip faults that extends through the crust and into the upper mantle represent large lithospheric deformation that may eventually create a localized boundary between the indian and australian plates fred pollitz and colleagues show that in the six days following 11 april the global rate of remote earthquakes with magnitudes greater than 5 5 increased nearly fivefold and events up to magnitude 7 seem to have been triggered the unprecedented delayed triggering power of this earthquake may arise from its strike slip source geometry or because it struck at a time of an unusually low global earthquake rate and increased the number of nucleation sites that were very close to failure the indo australian plate is undergoing distributed internal deformation caused by the lateral transition along its northern boundary from an environment of continental collision to an island arc subduction zone1 2 on 11 april 2012 one of the largest strike slip earthquakes ever recorded seismic moment magnitude mw 8 7 occurred about 100 200 kilometres southwest of the sumatra subduction zone occurrence of great intraplate strike slip faulting located seaward of a subduction zone is unusual it results from northwest southeast compression within the plate caused by the india eurasia continental collision to the northwest together with northeast southwest extension associated with slab pull stresses as the plate underthrusts sumatra to the northeast here we use seismic wave analyses to reveal that the 11 april 2012 event had an extraordinarily complex four fault rupture lasting about 160 seconds and was followed approximately two hours later by a great mw 8 2 aftershock the mainshock rupture initially expanded bilaterally with large slip 20 30 metres on a right lateral strike slip fault trending west northwest to east southeast wnw ese and then bilateral rupture was triggered on an orthogonal left lateral strike slip fault trending north northeast to south southwest nne ssw that crosses the first fault this was followed by westward rupture on a second wnw ese strike slip fault offset about 150 kilometres towards the southwest from the first fault finally rupture was triggered on another en echelon wnw ese fault about 330 kilometres west of the epicentre crossing the ninetyeast ridge the great aftershock with an epicentre located 185 kilometres to the ssw of the mainshock epicentre ruptured bilaterally on a nne ssw fault the complex faulting limits our resolution of the slip distribution these great ruptures on a lattice of strike slip faults that extend through the crust and a further 30 40 kilometres into the upper mantle represent large lithospheric deformation that may eventually lead to a localized boundary between the indian and australian plates

laramide uplift near the ray and resolution porphyry copper deposits southeastern arizona insights into regional shortening style magnitude of uplift and implications for exploration

coseismic slip of the 2010 mw 8 8 great maule chile earthquake quantified by the inversion of grace observations abstract the 27 february 2010 mw 8 8 maule chile earthquake ruptured over 500 km along a mature seismic gap between 34 s and 38 s the concepcion constitucion gap where no large megathrust earthquakes had occurred since the 1835 mw 8 5 event notable discrepancies exist in slip distribution and moment magnitude estimated by various models inverted using traditional observations such as teleseismic networks coastal river markers tsunami sensors global positioning system gps and interferometric synthetic aperture radar insar we conduct a spatio spectral localization analysis based on slepian basis functions of data from gravity recovery and climate experiment grace to extract coseismic gravity change signals of the maule earthquake with improved spatial resolution 350 km half wavelength our results reveal discernible differences in the average slip between the grace observation and predictions from various coseismic models the sensitivity analysis reveals that grace observation is sensitive to the size of the fault but unable to separate depth and slip here we assume the depth of the fault is known and simultaneously invert for the fault plane area and the average slip using the simulated annealing algorithm our grace inverted fault plane length and width are 429 6 km 146 5 km respectively the estimated slip is 8 1 1 2 m indicating that most of the strain accumulated since 1835 in the concepcion constitucion gap was released by the 2010 maule earthquake

improved constraints on seismic source parameters of the 2011 tohoku earthquake from grace gravity and gravity gradient changes a new approach of using only the north component of gravity change from gravity recovery and climate experiment grace data reveals that a substantially higher spatial resolution of the observed seismic deformation following the 2011 tohoku earthquake is achievable at 333 km or longer here we show that grace observed north component of gravity change 17 6 1 1 gal and the corresponding gravity gradient change e g txz at 1 25 0 09 meotvos agree well with seismic gps model predictions localized slepian spectrum analysis further confirms that the grace gravity and gravity gradient changes agree well with seismic model spectra and have powers up to the limit of the grace solution complete to spherical harmonic degree 60 using the gravity observations for the fault parameter inversion via simulated annealing algorithm we show that the estimated slip orientation and centroid location are different from gps seismic solutions and potentially due to the additional offshore constraint from grace data

coseismic slip and afterslip of the great mw 9 15 sumatra andaman earthquake of 2004 we determine coseismic and the first month postseismic deformation associated with the sumatra andaman earthquake of 26 december 2004 from near field global positioning system gps surveys in northwestern sumatra and along the nicobar andaman islands continuous and campaign gps measurements from thailand and malaysia and in situ and remotely sensed observations of the vertical motion of coral reefs the coseismic model shows that the sunda subduction mega thrust ruptured over a distance of about 1500 km and a width of less than 150 km releasing a total moment of 6 7 7 0 10 22 n m equivalent to a magnitude m w 9 15 the latitudinal distribution of released moment in our model has three distinct peaks at about 4 n 7 n and 9 n which compares well to the latitudinal variations seen in the seismic inversion and of the analysis of radiated t waves our coseismic model is also consistent with interpretation of normal modes and with the amplitude of very long period surface waves the tsunami predicted from this model fits rela tively well the altimetric measurements made by the jason and topex satellites neither slow nor delayed slip is needed to explain the normal modes and the tsunami wave the near field geodetic data that encompass both coseismic deformation and up to 40 days of postseismic deformation require that slip must have continued on the plate interface after the 500 sec long seismic rupture the postseismic geodetic moment of about 2 4 10 22 nm mw 8 8 is equal to about 30 5 of the coseismic moment release evolution of postseismic deformation is consistent with rate strengthening frictional afterslip online material summary of geodetic data used in this study

teleseismic inversion for rupture process of the 27 february 2010 chile mw 8 8 earthquake the 27 february 2010 chile m w 8 8 earthquake is the fifth largest earthquake to strike during the age of seismological instrumentation the faulting geometry slip distribution seismic moment and moment rate function are estimated from broadband teleseismic p sh and rayleigh wave signals we explore some of the trade offs in the rupture process estimation due to model parameterizations limited teleseismic sampling of seismic phase velocities and uncertainty in fault geometry the average slip over the 81 500 km 2 rupture area is about 5 m with slip concentrations down dip up dip and southwest and up dip and north of the hypocenter relatively little slip occurred up dip offshore of the hypocenter the average rupture velocity is 2 0 2 5 km s

long and short term postseismic gravity changes of megathrust earthquakes from satellite gravimetry using monthly satellite gravimetry data we studied time variable gravity field after three m9 class earthquakes the 2004 sumatra andaman 2010 chile maule and 2011 tohoku oki earthquakes the observations showed that the gravity typically 1 decreases coseismically 2 continues to decrease for a few months and 3 increases over a longer period therefore postseismic gravity changes have two components with different time constants and polarities the mechanisms of short and long term postseismic gravity changes are not as clear as coseismic changes at the moment but might be explained to some extent with afterslip and the maxwell viscoelasticity respectively these two components are difficult to discriminate with surface velocity measurements because the forearc area moves trenchward at both stages they appear in different polarities in gravity making satellite gravimetry a unique tool to separate them

source parameter inversion for recent great earthquakes from a decade long observation of global gravity fields we quantify gravity changes after great earthquakes present within the 10 year long time series of monthly gravity recovery and climate experiment grace gravity fields using spherical harmonic normal mode formulation the respective source parameters of moment tensor and double couple were estimated for the 2004 sumatra andaman earthquake the gravity data indicate a composite moment of 1 2 1023 n m with a dip of 10 in agreement with the estimate obtained at ultralong seismic periods for the 2010 maule earthquake the grace solutions range from 2 0 to 2 7 1022 n m for dips of 12 24 and centroid depths within the lower crust for the 2011 tohoku oki earthquake the estimated scalar moments range from 4 1 to 6 1 1022 n m with dips of 9 19 and centroid depths within the lower crust for the 2012 indian ocean strike slip earthquakes the gravity data delineate a composite moment of 1 9 1022 n m regardless of the centroid depth comparing favorably with the total moment of the main ruptures and aftershocks the smallest event we successfully analyzed with grace was the 2007 bengkulu earthquake with m0 5 0 1021 n m we found that the gravity data constrain the focal mechanism with the centroid only within the upper and lower crustal layers for thrust events deeper sources i e in the upper mantle could not reproduce the gravity observation as the larger rigidity and bulk modulus at mantle depths inhibit the interior from changing its volume thus reducing the negative gravity component focal mechanisms and seismic moments obtained in this study represent the behavior of the sources on temporal and spatial scales exceeding the seismic and geodetic spectrum

the great sumatra andaman earthquake of 26 december 2004 the two largest earthquakes of the past 40 years ruptured a 1600 kilometer long portion of the fault boundary between the indo australian and southeastern eurasian plates on 26 december 2004 seismic moment magnitude mw 9 1 to 9 3 and 28 march 2005 mw 8 6 the first event generated a tsunami that caused more than 283 000 deaths fault slip of up to 15 meters occurred near banda aceh sumatra but to the north along the nicobar and andaman islands rapid slip was much smaller tsunami and geodetic observations indicate that additional slow slip occurred in the north over a time scale of 50 minutes or longer

earth s free oscillations excited by the 26 december 2004 sumatra andaman earthquake at periods greater than 1000 seconds earth s seismic free oscillations have anomalously large amplitude when referenced to the harvard centroid moment tensor fault mechanism which is estimated from 300 to 500 second surface waves by using more realistic rupture models on a steeper fault derived from seismic body and surface waves we approximated free oscillation amplitudes with a seismic moment 6 5 10 22 newton meters that corresponds to a moment magnitude of 9 15 with a rupture duration of 600 seconds the fault rupture models represent seismic observations adequately but underpredict geodetic displacements that argue for slow fault motion beneath the nicobar and andaman islands

coseismic slip distribution of the february 27 2010 mw 8 8 maule chile earthquake 1 static offsets produced by the february 27 2010 mw 8 8 maule chile earthquake as measured by gps and insar constrain coseismic slip along a section of the andean megathrust of dimensions 650 km in length 180 km in width gps data have been collected from both campaign and continuous sites sampling both the near field and far field alos palsar data from several ascending and descending tracks constrain the near field crustal deformation inversions of the geodetic data for distributed slip on the megathrust reveal a pronounced slip maximum of order 15 m at 15 25 km depth on the megathrust offshore lloca indicating that seismic slip was greatest north of the epicenter of the bilaterally propagating rupture a secondary slip maximum appears at depth 25 km on the megathrust just west of concepcion coseismic slip is negligible below 35 km depth estimates of the seismic moment based on different datasets and modeling approaches vary from 1 8 to 2 6 1022 n m our study is the first to model the static displacement field using a layered spherical earth model allowing us to incorporate both near field and far field static displacements in a consistent manner the obtained seismic moment of 1 97 1022 n m corresponding to a moment magnitude of 8 8 is similar to that obtained by previous seismic and geodetic inversions

improved source parameter constraints for five undersea earthquakes from north component of grace gravity and gravity gradient change measurements abstract the innovative processing of gravity recovery and climate experiment grace data using only the north component of gravity change and its corresponding gravity gradient changes allows the enhancement of the spatial resolution for coseismic deformation signals here we report the study of five undersea earthquakes using this technique the 2004 sumatra andaman earthquake the 2007 bengkulu earthquake the 2010 maule chile earthquake the 2011 tohoku earthquake and the 2012 indian ocean earthquakes by using the high spherical harmonic degree up to degree 96 data products and the associated grace data processing techniques the retrieved north component of gravity change is up to 34 1 4 gal for the 2004 sumatra andaman earthquake which illustrates by far the highest amplitude of the coseismic signal retrieved from satellite gravimetry among previous studies we creatively apply the localized spectral analysis as an efficient method to empirically determine the practical spherical harmonic truncation degree by combining least squares adjustment with the simulated annealing algorithm point source parameters are estimated which demonstrates the unique constraint on source model from grace data compared to other data sources for the 2004 sumatra andaman earthquake grace data produce a shallower centroid depth 9 1 km as compared to the depth 28 3 km from gps data for the 2011 tohoku earthquake the grace estimated centroid location is southwest of the gps seismic solutions and the slip orientation is about 10 clockwise from the published gps seismic slip models we concluded that these differences demonstrate the additional and critical offshore constraint by grace on source parameters as compared to gps seismic data

the 2011 mw 9 0 tohoku earthquake comparison of gps and strong motion data near field ground motion data are available in semi real time either from modern strong motion or continuous global positioning system gps networks allowing robust solutions for earthquake source parameters which are useful for rapid disaster assessment and early warning these wide applications require the ground motion data to cover a very broad frequency band that however is usually not available this paper presents a case study on the 2011 m w 9 0 tohoku earthquake showing how the ground motion information from geodetic and seismic instrumentations is complementary and suggesting the joint use of both types of data particularly when the network coverage is sparse first the strong motion records from the two japanese networks k net and kik net are analyzed using an automatic empirical baseline correction tool the static coseismic displacement data are obtained by double integration and then used to derive the permanent slip distribution on the earthquake fault comparisons with the corresponding gps based solutions yield a quantitative estimation of uncertainties of the empirical baseline correction furthermore a dozen nearby gps and strong motion station pairs are selected to demonstrate that the information in their time series agrees with each other finally methods for combining both types of ground motion observation systems are discussed and the wide applicability of this approach is highlighted

slip of the 2004 sumatra andaman earthquake from joint inversion of long period global seismic waveforms and gps static offsets the 26 december 2004 great sumatra andaman earthquake opened a new era for seismologists to understand the complex source process of a great earth quake this is the first event with moment magnitude greater than 9 since the de ployment of high dynamic range broadband seismic and global positioning system gps sensors around the globe this study presents an analysis of the ruptured fault plane geometry and slip distribution using long period teleseismic data and gps measured static surface displacements near the fault plane we employ a rupture geometry with six along strike segments with and without a steeper down dip ex tension the fault segments are further subdivided into a total of 201 30 30 km fault patches sensitivity tests of fault plane geometry and the variation in rupture velocity indicate that the dip and curvature of the fault plane are not well resolved from the given data set and the rupture velocity is constrained to be between 1 8 and 2 6 km sec error estimations of the slip distribution using a random selection of seismic and gps station subsets 50 of all stations illustrate that slip is well re solved along the whole rupture and the mean slip uncertainty is less than 1 5 m about 11 although it is possible that near field gps data include contributions from additional postseismic transient deformation our preferred model suggests that the sumatra andaman earthquake had a magnitude of mw 9 20 0 05 0 06 online material comparison of slip models gps modeling waveform fit fault geometry and inversion parameters

the 2010 mw 8 8 maule megathrust earthquake of central chile monitored by gps large earthquakes produce crustal deformation that can be quantified by geodetic measurements allowing for the determination of the slip distribution on the fault we used data from global positioning system gps networks in central chile to infer the static deformation and the kinematics of the 2010 moment magnitude m w 8 8 maule megathrust earthquake from elastic modeling we found a total rupture length of 500 kilometers where slip up to 15 meters concentrated on two main asperities situated on both sides of the epicenter we found that rupture reached shallow depths probably extending up to the trench resolvable afterslip occurred in regions of low coseismic slip the low frequency hypocenter is relocated 40 kilometers southwest of initial estimates rupture propagated bilaterally at about 3 1 kilometers per second with possible but not fully resolved velocity variations

gravitational seismology retrieving centroid moment tensor solution of the 2011 tohoku earthquake 1 mass rearrangement within the crust and lithospheric mantle and ocean water redistribution caused by great earthquakes are made visible by their coseismic gravity signature nowadays detectable by the gravity recovery and climate experiment grace space mission here we present a novel procedure for estimating the principal seismic source parameters hypocenter and moment tensor that relies solely on space gravity data from grace applied for the first time to the 2011 tohoku earthquake it yields a seismic source model that is consistent with a thrust earthquake and geological information of the subduction zone it closely resembles the global centroid moment tensor project solution based on the teleseismic wave inversion although the moment magnitude is higher 9 13 0 11 compared to 9 08 and the hypocenter is further offshore by about 40 km within the oceanic plate this procedure will become an important tool in seismology as it complements centroid moment tensor analysis by exploiting the new gravity data from grace

slip distribution of the 2007 bengkulu earthquake inferred from tsunami waveforms and insar data 1 joint inversion study using tsunami waveforms and insar data provides a new way to understand the magnitude and spatial extent of subduction zone earthquakes a great earthquake mw 8 5 occurred on 12 september 2007 off the west coast of bengkulu indonesia the tsunami generated by the event was recorded by tide gauge stations around the indian ocean and by two bottom pressure sensors in the deep sea the ground surface displacements produced by the earthquake on pagai islands and on sumatra island were observed by interferometric synthetic aperture radar insar we estimated the slip distribution of the earthquake by joint inversion incorporating a spatial smoothness constraint using tsunami waveforms and insar data the total released seismic moment calculated from the slip distribution is 6 7 1021 n m mw 8 5 consistent with the seismic moment of the global cmt solution 6 71 1021 n m the maximum observed tsunami heights along the coast of bengkulu agree with those computed from the slip distribution the slip amount of the 2007 earthquake is smaller than the amount of potential slip that has been accumulated since after the 1797 and 1833 events the premise is that averaged over long periods of time the entire fault must slip equal amounts therefore the 2007 great earthquake could be followed by several great earthquakes that will rupture the plate interface until the potential slip that has been accumulated is completely released

contribution of satellite gravimetry to understanding seismic source processes of the 2011 tohoku oki earthquake 1 the 2011 great tohoku oki earthquake apart from shaking the ground perturbed the motions of satellites orbiting some hundreds km away above the ground such as grace due to coseismic change in the gravity field significant changes in inter satellite distance were observed after the earthquake these unconventional satellite measurements were inverted to examine the earthquake source processes from a radically different perspective that complements the analyses of seismic and geodetic ground recordings we found the average slip located up dip of the hypocenter but within the lower crust as characterized by a limited range of bulk and shear moduli the grace data constrained a group of earthquake source parameters that yield increasing dip 7 16 2 and simultaneously decreasing moment magnitude 9 17 9 02 0 04 with increasing source depth 15 24 km the grace solution includes the cumulative moment released over a month and demonstrates a unique view of the long wavelength gravimetric response to all mass redistribution processes associated with the dynamic rupture and short term postseismic mechanisms to improve our understanding of the physics of megathrusts

structural characteristics off miyagi forearc region the japan trench seismogenic zone deduced from a wide angle reflection and refraction study abstract the japan trench subduction zone located east of ne japan has regional variation in seismicity many large earthquakes occurred in the northern part of japan trench but few in the southern part off miyagi region is in the middle of the japan trench where the large earthquakes m 7 with thrust mechanisms have occurred at an interval of about 40 years in two parts inner trench slope and near land a seismic experiment using 36 ocean bottom seismographs obs and a 12 000 cu in airgun array was conducted to determine a detailed 2d velocity structure in the forearc region off miyagi the depth to the moho is 21 km at 115 km from the trench axis and becomes progressively deeper landward the p wave velocity of the mantle wedge is 7 9 8 1 km s which is typical velocity for uppermost mantle without large serpentinization the dip angle of oceanic crust is increased from 5 6 near the trench axis to 23 150 km landward from the trench axis the p wave velocity of the oceanic uppermost mantle is as small as 7 7 km s this low velocity oceanic mantle seems to be caused by not a lateral anisotropy but some subduction process by comparison with the seismicity off miyagi the subduction zone can be divided into four parts 1 seaward of the trench axis the seismicity is low and normal fault type earthquakes occur associated with the destruction of oceanic lithosphere 2 beneath the deformed zone landward of the trench axis the plate boundary is characterized as a stable sliding fault plain in case of earthquakes this zone may be tsunamigenic 3 below forearc crust where p wave velocity is almost 6 km s and larger this zone is the seismogenic zone below inner trench slope which is a plate boundary between the forearc and oceanic crusts 4 below mantle wedge the rupture zones of thrust large earthquakes near land e g 1978 off miyagi earthquake are located beneath the mantle wedge the depth of the rupture zones is 30 50 km below sea level from the comparison the rupture zones of large earthquakes off miyagi are limited in two parts plate boundary between the forearc and oceanic crusts and below mantle wedge this limitation is a rare case for subduction zone although the seismogenic process beneath the mantle wedge is not fully clarified our observation suggests the two possibilities earthquake generation at the plate boundary overridden by the mantle wedge without serpentinization or that in the subducting slab

partial rupture of a locked patch of the sumatra megathrust during the 2007 earthquake sequence the great sumatra andaman earthquake and tsunami of 2004 was a dramatic reminder of the importance of understanding the seismic and tsunami hazards of subduction zones 1 2 3 4 in march 2005 the sunda megathrust ruptured again producing an event 5 of moment magnitude mw 8 6 south of the 2004 rupture area which was the site of a similar event in 1861 ref 6 concern was then focused on the mentawai area where large earthquakes had occurred in 1797 mw 8 8 and 1833 mw 9 0 6 7 two earthquakes one of mw 8 4 and twelve hours later one of mw 7 9 indeed occurred there on 12 september 2007 here we show that these earthquakes ruptured only a fraction of the area ruptured in 1833 and consist of distinct asperities within a patch of the megathrust that had remained locked in the interseismic period this indicates that the same portion of a megathrust can rupture in different patterns depending on whether asperities break as isolated seismic events or cooperate to produce a larger rupture this variability probably arises from the influence of non permanent barriers zones with locally lower pre stress due to the past earthquakes the stress state of the portion of the sunda megathrust that had ruptured in 1833 and 1797 was probably not adequate for the development of a single large rupture in 2007 the moment released in 2007 amounts to only a fraction both of that released in 1833 and of the deficit of moment that had accumulated as a result of interseismic strain since 1833 the potential for a large megathrust event in the mentawai area thus remains large

broadscale postseismic gravity change following the 2011 tohoku oki earthquake and implication for deformation by viscoelastic relaxation and afterslip the analysis of grace gravity data revealed postseismic gravity increase by 6 gal over a 500 km scale within a couple of years after the 2011 tohoku oki earthquake which is nearly 40 50 of the coseismic gravity change it originates mostly from changes in the isotropic component corresponding to the mrr moment tensor element the exponential decay with rapid change in a year and gradual change afterward is a characteristic temporal pattern both viscoelastic relaxation and afterslip models produce reasonable agreement with the grace free air gravity observation while their bouguer gravity patterns and seafloor vertical deformations are distinctly different the postseismic gravity variation is best modeled by the biviscous relaxation with a transient and steady state viscosity of 1018 and 1019 pa s respectively for the asthenosphere our calculated higher resolution viscoelastic relaxation model underlying the partially ruptured elastic lithosphere yields the localized postseismic subsidence above the hypocenter reported from the gps acoustic seafloor surveying

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

correction to coseismic slip distribution of the february 27 2010 mw 8 8 maule chile earthquake 1 in the paper coseismic slip distribution of the february 27 2010 mw 8 8 maule chile earthquake by fred f pollitz et al geophysical research letters 38 l09309 doi 10 1029 2011gl047065 2011 the captions for figure 1 3 are ordered incorrectly the correct captions for figures 1 3 appear here 2 figure 1 rupture areas associated with historic earthquakes along the andean megathrust and aftershocks of the february 27 2010 event historical epicenters are provided by centro regional de sismologia para america del sur and aftershock locations are provided by the national earthquake information center white lines indicate the surface projection of the fault plane used to model the 2010 event nazca south america relative plate motion vector is from ruegg et al 2009 3 figure 2 observed coseismic gps offsets black vectors with 95 uncertainties compared with model horizontal offsets using the coseismic slip model obtained by the joint insar gps inversion which is contoured in gray values in meters white lines indicate the surface projection of the fault plane 4 figure 3 coseismic slip models derived from a insar data only b gps data only and c combined gps and insar data with seismic moment indicated for each model contour interval is 3 m star symbol indicates the global cmt epicenter

april 2012 intra oceanic seismicity off sumatra boosted by the banda aceh megathrust the two earthquakes of respective magnitudes 8 6 and 8 2 that occurred off the coast of the sumatra subduction zone on 11 april 2012 are shown to be part of a continuing boost of the intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes on 11 april 2012 two of the largest strike slip earthquakes ever recorded at magnitudes of 8 7 and 8 2 occurred in the northeastern indian ocean a few hundred kilometres off the coast of sumatra three groups now report the analysis of seismic data from the days and months before and after these events as well as the events themselves matthias delescluse and co authors show that these earthquakes are part of the ongoing boost of intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes they conclude that the australian plate driven by slab pull forces at the sunda trench is gradually detaching from the indian plate han yue and colleagues show that the 11 april event involved a complex four fault rupture lasting several minutes followed two hours later by a magnitude 8 2 aftershock these great ruptures on a lattice of strike slip faults that extends through the crust and into the upper mantle represent large lithospheric deformation that may eventually create a localized boundary between the indian and australian plates fred pollitz and colleagues show that in the six days following 11 april the global rate of remote earthquakes with magnitudes greater than 5 5 increased nearly fivefold and events up to magnitude 7 seem to have been triggered the unprecedented delayed triggering power of this earthquake may arise from its strike slip source geometry or because it struck at a time of an unusually low global earthquake rate and increased the number of nucleation sites that were very close to failure large earthquakes nucleate at tectonic plate boundaries and their occurrence within a plate s interior remains rare and poorly documented especially offshore the two large earthquakes that struck the northeastern indian ocean on 11 april 2012 are an exception they are the largest strike slip events reported in historical times1 2 and triggered large aftershocks worldwide3 yet they occurred within an intra oceanic setting along the fossil fabric of the extinct wharton basin rather than on a discrete plate boundary4 5 6 7 8 here we show that the 11 april 2012 twin earthquakes are part of a continuing boost of the intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes subsequent to a stress transfer process recognized at other subduction zones9 10 using coulomb stress change calculations we show that the coseismic slips of the aceh and nias earthquakes can promote oceanic left lateral strike slip earthquakes on pre existing meridian aligned fault planes we further show that persistent viscous relaxation in the asthenospheric mantle several years after the aceh megathrust explains the time lag between the 2004 megathrust and the 2012 intraplate events on a short timescale the 2012 events provide new evidence for the interplay between megathrusts at the subduction interface and intraplate deformation offshore on a longer geological timescale the australian plate driven by slab pull forces at the sunda trench is detaching from the indian plate which is subjected to resisting forces at the himalayan front6 8 11

coseismic gravity changes of the 2011 tohoku oki earthquake from satellite gravimetry 1 the massive tohoku oki earthquake of a moment magnitude mw of 9 0 occurred on 11 march 2011 off the pacific coast of the northeastern japan the mass redistribution in and around the focal region associated with this earthquake was studied using the gravity changes detected by gravity recovery and climate experiment grace satellite after the 2004 sumatra andaman and the 2010 central chile maule earthquakes the present study presents the third case of clear detection of coseismic gravity changes by grace the observed gravity changes were dominated by decrease over the back arc region of 7 gal or less this reflects to a large extent coseismic crustal dilatation of the landward plate they agree well with the changes calculated with the green s function for the realistic earth using fault parameters inferred from coseismic crustal movements the spatial patterns of the gravity changes of these earthquakes are very similar because they are all shallow angle reverse faulting at convergent plate boundaries we found linear relationship between gravity decreases and seismic moments

regional gravity decrease after the 2010 maule chile earthquake indicates large scale mass redistribution 1 we report small but detectable changes in the grace satellites relative trajectory after the m8 8 maule chile earthquake on 27 february 2010 that can be used to delineate the shift in the gravity field a gravity anomaly of 5 gal with a spatial scale of 500 km was found east of the epicenter after the earthquake based on coseismic models the long wavelength negative gravity change is primarily the result of crustal dilatation as well as surface subsidence in the onland region the offshore positive gravity anomaly predicted from finite fault coseismic models is considerably smaller because the gravity changes due to surface uplift and interior deformation are opposite in polarity our study suggests a role for large scale gravity observations in deciphering changes of the earth s interior during great earthquakes by filling in the seldom observed long wavelength spectrum of earthquake deformations as a complement to surface geodetic measurements and seismic data

upper mantle rheology from grace and gps postseismic deformation after the 2004 sumatra andaman earthquake 1 mantle rheology is one of the essential yet least understood material properties of our planet controlling the dynamic processes inside the earth s mantle and the earth s response to various forces with the advent of grace satellite gravity measurements of mass displacements associated with many processes are now available in the case of mass displacements related to postseismic deformation these data may provide new constraints on the mantle rheology we consider the postseismic deformation due to the m w 9 2 sumatra 26 december 2004 and m w 8 7 nias 28 march 2005 earthquakes applying wavelet analyses to enhance those local signals in the grace time varying geoids up to september 2007 we detect a clear postseismic gravity signal we supplement these gravity variations with gps measurements of postseismic crustal displacements to constrain postseismic relaxation processes throughout the upper mantle the observed gps displacements and gravity variations are well explained by a model of visco elastic relaxation plus a small amount of afterslip at the downdip extension of the coseismically ruptured fault planes our model uses a 60 km thick elastic layer above a viscoelastic asthenosphere with burgers body rheology the mantle below depth 220 km has a maxwell rheology assuming a low transient viscosity in the 60 220 km depth range the grace data are best explained by a constant steady state viscosity throughout the ductile portion of the upper mantle e g 60 660 km this suggests that the localization of relatively low viscosity in the asthenosphere is chiefly in the transient viscosity rather than the steady state viscosity we find a 8 10 18 pa s mantle viscosity in the 220 660 km depth range this may indicate a transient response of the upper mantle to the high amount of stress released by the earthquakes to fit the remaining misfit to the grace data larger at the smaller spatial scales cumulative afterslip of about 75 cm at depth should be added over the period spanned by the grace models it produces only small crustal displacements our results confirm that satellite gravity data are an essential complement to ground geodetic and geophysical networks in order to understand the seismic cycle and the earth s inner structure

earthquake in a maze compressional rupture branching during the 2012 mw 8 6 sumatra earthquake seismological observations of the 2012 moment magnitude 8 6 sumatra earthquake reveal unprecedented complexity of dynamic rupture the surprisingly large magnitude results from the combination of deep extent high stress drop and rupture of multiple faults back projection source imaging indicates that the rupture occurred on distinct planes in an orthogonal conjugate fault system with relatively slow rupture speed the east southeast west northwest ruptures add a new dimension to the seismotectonics of the wharton basin which was previously thought to be controlled by north south strike slip faulting the rupture turned twice into the compressive quadrant against the preferred branching direction predicted by dynamic coulomb stress calculations orthogonal faulting and compressional branching indicate that rupture was controlled by a pressure insensitive strength of the deep oceanic lithosphere

tsunami generation by horizontal displacement of ocean bottom tsunami generation by an earthquake is generally modeled by water surface displacement identical to the vertical deformation of ocean bottom due to faulting the effect of horizontal deformation is usually neglected however when the tsunami source is on a steep slope and the horizontal displacement is large relative to the vertical displacement the effect becomes significant we show this for two recent earthquakes which generated much larger tsunamis than expected from seismic waves in the case of the 1994 june 2 java indonesia earthquake the focal mechanism was a very shallow dipping thrust and the source was near a very steep trench slope in the case of the 1994 nov 14 mindoro philippines earthquake strike slip faulting extended from ocean to land perpendicular to the coast line in both cases we found that the horizontal motion of slope had an important contribution to the tsunami generation

the size and duration of the sumatra andaman earthquake from far field static offsets the 26 december 2004 sumatra earthquake produced static offsets at continuously operating gps stations at distances of up to 4500 kilometers from the epicenter we used these displacements to model the earthquake and include consideration of the earth s shape and depth varying rigidity the results imply that the average slip was 5 meters along the full length of the rupture including the approximately 650 kilometer long andaman segment comparison of the source derived from the far field static offsets with seismically derived estimates suggests that 25 to 35 of the total moment release occurred at periods greater than 1 hour taking into consideration the strong dip dependence of moment estimates the magnitude of the earthquake did not exceed mw 9 2

is there a best source model of the sumatra 2004 earthquake for simulating the consecutive tsunami summary many studies have attempted to invert the fault source of the sumatra 2004 event whereas they mostly consider the same fault geometry they lead to a wide range of potential slip distributions using tsunami modelling with geowave a model based on fully non linear boussinesq equations we investigate the influence of five distinct source models of various origins and the influence of rupture kinematics on the generated tsunami the simulation results are considered both at ocean scale and at country scale we then compare the results along the jason 1 track to the corresponding sea surface height anomaly ssha profile and examine the patterns of maximum sea surface elevation around the bay of bengal and on the eastern and southern coastlines of sri lanka in most cases the synthetic ssha profiles are not very consistent with the observed one although they all display a prevailing first wave the divergence in maximum sea surface elevation appears in particular along the sri lankan coast where three of the models lead to a clearly underestimated tsunami impact the best models derive from purely seismic and geodetic studies that did not consider any tsunami modelling thus suggesting that the methods to invert a fault model from tsunami data still need some adjustment especially concerning the handling of coastal data in addition it is important to consider the rupture kinematics along such a long fault as the generated tsunami is more significant than when considering an instantaneous rupture in the case of the sumatra 2004 event the tsunami impact on sri lanka is notably underestimated if modelled without the rupture kinematics we conclude that for tsunami modelling a complex description of the fault source model is not absolutely necessary but some significant parameters such as rupture kinematics should be taken into account

coseismic and postseismic deformation of the 2011 tohoku oki earthquake constrained by grace gravimetry 1 spaceborne gravimetry data from the gravity recovery and climate experiment grace are processed using spatio spectral slepian localization analysis enabling the high resolution detection of permanent gravity change associated with both coseismic and postseismic deformation resulting from the great 11 march 2011 mw 9 0 tohoku oki earthquake the grace observations are then used in a geophysical inversion to estimate a new slip model containing both coseismic slip and after slip the grace estimated moment for the total slip up to the end of july 2011 is estimated as 4 59 0 49 1022 n m equivalent to a composite mw of 9 07 0 65 if the moment for the tohoku oki main shock is assumed to be 3 8 1022 n m the contribution from the after slip is estimated to be 3 0 1021 12 8 1021 n m in good agreement with a postseismic slip model inverted from gps data we conclude that grace data provide an independent constraint to quantify co and post seismic deformation for the tohoku oki event