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

crustal structure and moho geometry of the northeastern tibetan plateau as revealed by sinoprobe 02 deep seismic reflection profiling abstract underthrusting of india below eurasia has resulted in the formation of the himalayan and the qinghai tibet plateau distributed deformation coupled with block translation and rotation has generated the qilian shan thrust belt and a series of east and northwest striking strike slip faults across northeastern tibet because these structures lie in a transition zone between the high plateau region to the south and the lowlands of the north china craton in the north determining their deep crustal and upper mantle structures has important implications for unraveling the mechanism of tibetan plateau formation in this paper we present new results from the sinoprobe 02 deep seismic reflection project across the eastern part of the qilian shan and the southern margin of the alxa block interpretation of the reflection profile obtained from this study is based on constraints from surface geology and detailed geometric analysis of structural relationships among key reflectors in the crust and the upper mantle our results indicate that the upper crust of the eastern qilian shan is characterized by fault bend folds and duplex systems involving phanerozoic strata that may have resulted from early paleozoic collisional tectonics and cenozoic intra continental deformation locally half graben structures hosting cretaceous strata are also present the active structures in the region are dominated by left slip haiyuan and tianjian fault systems marking the northern margin of the tibetan plateau the strike slip structures have variable dips and dip directions and sole into a common decollement with a depth of 40 45 km because the two faults do not cut and offset the moho below the active crustal and mantle deformation in the northeastern tibet must be decoupled

rapid exhumation at 8 ma on the liupan shan thrust fault from apatite fission track thermochronology implications for growth of the northeastern tibetan plateau margin abstract the liupan shan mountain is one of the outermost ranges in northeastern tibetan plateau the onset of its uplift provides insight on whether the plateau grew sequentially outward or broad areas of the plateau deformed simultaneously the apatite fission track method can be used to date rapid cooling as the result of unroofing of rocks in response to tectonically induced vertical motion fission track data from apatite in early cretaceous sedimentary strata exposed on the hanging wall of liupan shan thrust fault in northeastern tibet suggest that a late cenozoic rapid cooling events occurred at 7 3 8 2 ma or 8 ma this age apparently dates fault activity of the liupan shan thrust in response to northeastward growth of the tibetan plateau uplift and lateral growth which continues today numerous studies of the tibetan plateau suggest that the onset of deformation in eastern and northern margin of tibetan plateau occurred in the latest miocene

postglacial left slip rate and past occurrence of m 8 earthquakes on the western haiyuan fault gansu china high resolution hr air photographs and a 1 m horizontal and 2 m vertical resolution digital elevation model derived from them by stereophotogrammetry provide new constraints on the behavior of the western stretch of the active haiyuan fault in gansu province china the photographs cover three swaths along the fault each about 2 km long and at least 500 m wide near the village of songshan at 103 5oe this high resolution data set is used to map and measure cumulative horizontal offsets of alluvial terraces and risers that range between 115 and la 135 m and 70 and 90 m at two sites dating these terraces with 14c yields minimum and maximum ages of 8400 and 7600 and 14 200 years b p respectively this leads to a postglacial slip rate of 12 4 mm yr with a most likely minimum value of 11 6 1 1 mm yr the smallest stream offsets observed on the hr photographs range between 8 and 16 m and are interpreted as coseismic displacements of the last few earthquakes with m 8 that ruptured the 220 km long tianzhu gap of the fault west of the yellow river earthquakes of that size within this gap which has been quiescent for at least 800 years would recur at intervals of 1050 450 years

characteristic slip for five great earthquakes along the fuyun fault in china the seismic hazard associated with an individual fault can be assessed from the distributions of slip and recurrence times of earthquakes however seismic cycle models 1 that aim to predict rupture lengths and fault displacements of successive earthquakes on one fault remain poorly validated it is therefore unknown whether individual fault segments rupture independently producing earthquakes with a diverse range of magnitudes and recurrence times or slip by characteristic amounts with characteristic magnitudes here we use highresolution satellite data to document the horizontal offsets of stream channels and terraces created by strike slip motion on the fuyun fault xinjiang china during five historical earthquakes we find that the ms 7 9 11 august 1931 earthquake produced a surface rupture with a length of 160 km dispersed over three different fault segments the 290 measured stream channel and terrace offsets record an average slip of 6 3 m we use the degree of preservation of geomorphological markers to assign relative ages to individual fault offsets and identify at least four distinct older earthquakes we find that these older earthquakes also produced fault offsets with a similar distribution to the 1931 earthquake as the slip distributions during five successive earthquakes were so similar we conclude that ruptures on the fuyun fault obey a characteristic slip model very few large earthquakes are known to have ruptured the same fault segment twice in historical or instrumental time 1 the

rupture termination at restraining bends the last great earthquake on the altyn tagh fault strike slip rupture propagation falters where changes in fault strike increase coulomb failure stress numerical models of this phenomenon offer predictions of rupture extent based on bend geometry but have not been verified with field data to test model predictions of rupture barriers we examine rupture extent along a section of the sinistral altyn tagh fault punctuated by three major double bends we measure 3 8 m offsets and map 95 km of continuous scarps that define the most recent surface rupture we document the eastern terminus of this rupture within the aksay bend where an undeformed pleistocene alluvial fan we mapped and dated overlaps the fault we conclude based on this geomorphologic evidence that multiple holocene ruptures have stopped in the aksay bend our field data validate model predictions of rupture termination at a 18 restraining bend and support use of geometric parameters to define expected earthquake sizes in seismic hazard models

fast late pleistocene slip rate on the leng long ling segment of the haiyuan fault qinghai china 1 fieldwork along the western haiyuan fault where it cuts young glacial landforms in the leng long ling range qinghai northeastern tibet yields new constraints on its long term left slip rate our mapping near 101 85 e based on aerial photographs 1 50 000 topographic maps and spot images shows glacial valley edges and lateral moraines offset 200 m by the fault quartz rich cobbles were sampled on top of one moraine for in situ 10be and 26al cosmogenic nuclide dating among 12 dated samples the 6 oldest show ages clustering at 10 300 339 years this age probably reflects the time of last reshaping of the moraine before the valley glacier withdrew south of the fault around the end of the younger dryas 11 000 years b p assuming that the 200 40 m moraine offset started to be recorded after glacial retreat across the fault constrains the late pleistocene slip rate on the leng long ling segment of the haiyuan fault to be 19 5 mm yr

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

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

isc gem global instrumental earthquake catalogue 1900 2009 i data collection from early instrumental seismological bulletins abstract in order to produce a new global reference earthquake catalogue based on instrumental data covering the last 100 years of global earthquakes we collected digitized and processed an unprecedented amount of printed early instrumental seismological bulletins with fundamental parametric data for relocating and reassessing the magnitude of earthquakes that occurred in the period between 1904 and 1970 this effort was necessary in order to produce an earthquake catalogue with locations and magnitudes as homogeneous as possible the parametric data obtained and processed during this work fills a large gap in electronic bulletin data availability this new dataset complements the data publicly available in the international seismological centre isc bulletin starting in 1964 with respect to the amplitude period data necessary to re compute magnitude we searched through the global collection of printed bulletins stored at the isc and entered relevant station parametric data into the database as a result over 110 000 surface and body wave amplitude period pairs for re computing standard magnitudes m s and m b were added to the isc database to facilitate earthquake relocation different sources have been used to retrieve body wave arrival times these were entered into the database using optical character recognition methods international seismological summary 1918 1959 or manually e g british association for the advancement of science 1913 1917 in total 1 000 000 phase arrival times were added to the isc database for large earthquakes that occurred in the time interval 1904 1970 the selection of earthquakes for which data was added depends on time period and magnitude for the early years of last century until 1917 only very large earthquakes were selected for processing m 7 5 whereas in the periods 1918 1959 and 1960 2009 the magnitude thresholds are 6 25 and 5 5 respectively such a selection was mainly dictated by limitations in time and funding although the newly available parametric data is only a subset of the station data available in the printed bulletins its electronic availability will be important for any future study of earthquakes that occurred during the early instrumental period

coseismic slip variation assessed from terrestrial lidar scans of the el mayor cucapah surface rupture abstract we analyze high resolution 103 points m2 terrestrial lidar surveys of the 4 april 2010 el mayor cucapah earthquake rupture baja california mexico collected at three sites 12 18 days after the event using point cloud based tools in an immersive visualization environment we quantify coseismic fault slip for hundreds of meters along strike and construct densely constrained along strike slip distributions from measurements of offset landforms uncertainty bounds for each offset determined empirically by repeatedly measuring offsets at each site sequentially illuminate measurement uncertainties that are difficult to quantify in the field these uncertainties are used to define length scales over which variability in slip distributions may be assumed to reflect either recognizable earthquake mechanisms or measurement noise at two sites characterized by 2 3 m of concentrated right oblique slip repeat measurements yield 2 uncertainties of 11 12 each site encompasses 200 m along strike and a smoothed linear slip gradient satisfies all measurement distributions implying along fault strains of 10 3 conversely the common practice of defining the slip curve by the local slip maxima distorts the curve overestimates along fault strain and may overestimate actual fault slip by favoring measurements with large positive uncertainties at a third site characterized by 1 2 5 m of diffuse normal slip repeat measurements of fault throw summed along fault perpendicular profiles yield 2 uncertainties of 17 here a low order polynomial fit through the measurement averages best approximates surface slip however independent measurements of off fault strain accommodated by hanging wall flexure suggest that over the 200 m length of this site a linear interpolation through the average values for the slip maxima at either end of this site most accurately represents subsurface displacement in aggregate these datasets show that given uncertainties of greater than 11 2 slip distributions over shorter scales are likely to be less uneven than those derived from a single set of field or lidar based measurements this suggests that the relatively smooth slip curves we obtain over 102 m distances reflect real physical phenomena whereas short wavelength variability over 100 101 m distances can be attributed to measurement uncertainty

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

fault slip and earthquake recurrence along strike slip faults contributions of high resolution geomorphic data article i nfo understanding earthquake eq recurrence relies on information about the timing and size of past eq ruptures along a given fault knowledge of a fault s rupture history provides valuable information on its potential future behavior enabling seismic hazard estimates and loss mitigation stratigraphic and geomorphic evidence of faulting is used to constrain the recurrence of surface rupturing eqs analysis of the latter data sets culminated during the mid 1980s in the formulation of now classical eq recurrence models now routinely used to assess seismic hazard within the last decade light detection and ranging lidar surveying technology and other high resolution data sets became increasingly available to tectono geomorphic studies promising to contribute to better informed models of eq recurrence and slip accumulation patterns after reviewing motivation and background we outline requirements to successfully reconstruct a fault s offset accumulation pattern from geomorphic evidence we address sources of uncertainty affecting offset measure ment and advocate approaches to minimize them a number of recent studies focus on single eq slip distribu tions and along fault slip accumulation patterns we put them in context with paleoseismic studies along the respective faults by comparing coefficients of variation cv for eq inter event time and slip per event and find that a single event offsets vary over a wide range of length scales and the sources for offset variability differ with length scale b at fault segment length scales single event offsets are essentially constant c along fault offset accumulation as resolved in the geomorphic record is dominated by essentially same size large offset in crements and d there is generally no one to one correlation between the offset accumulation pattern constrained in the geomorphic record and eq occurrence as identified in the stratigraphic record revealing the higher resolution and preservation potential of the latter while slip accumulation along a fault segment may be dominated by repetition of large nearly constant offset increments timing of surface rupture is less regular

assessing the ability of pleiades stereo imagery to determine height changes in earthquakes a case study for the el mayor cucapah epicentral area high resolution surface topography is valuable for studying coseismic fault zone deformation and fault geometry it enables us to measure three dimensional surface displacements in earthquakes as shown in recent studies that used light detection and ranging lidar to determine coseismic motion however the applicability of lidar is limited by its relatively high cost and low availability in this study we use the 2010 el mayor cucapah earthquake to demonstrate the capability of pleiades stereo imagery to measure coseismic vertical ground displacement we acquired post earthquake pleiades tri stereo imagery from backward near nadir and forward orientations for a 45 km 7 km portion of the epicentral area 1 m resolution digital elevation models dems were produced with the four different combinations of incidence angles and compared to the post earthquake lidar dem elevations from tri stereo have slightly 15 smaller uncertainties than bi stereo as the tri stereo dem incorporates more observations elevation differences between the pleiades and post earthquake lidar dems show that the vertical accuracy of the pleiades dems is 0 3 m by differencing the pleiades dem and the pre earthquake 5 m resolution lidar dem we mapped metre and sub metre offsets along the faults obtaining results comparable to a previous study that differenced the two lidar dems this is the first case study of assessing very high resolution vhr satellite stereo imagery to determine sub metre vertical ground displacement in an earthquake by extension we expect it to be possible to measure sub metre vertical offsets occurring in earthquakes using pre and post earthquake vhr stereo imagery

why large earthquakes do not nucleate at shallow depths although by definition tectonic earthquakes may nucleate anywhere within the seismogenic layer in almost all cases those earthquakes that become large nucleate near the base of the seismogenic layer because frictional strength and stress drop should increase with depth and in situ stress measurements suggest that the ambient stress increases with depth we have examined spontaneous rupture models with gradients of both average stress drop and average strength relative to ambient stress to determine whether this explains the observed phenomena we report here that ruptures that are nucleated with in the low stress drop shallow regions of the model are inhibited from propagating but those that are nucleated within the high stress drop regions can propagate over the entire fault plane

active faulting and tectonics of the ningxia hui autonomous region china strike slip thrust and normal faulting all seem to play an active role in the tectonics of ningxia in the southernmost part of the region a major left lateral strike slip fault enters the region from the neighboring gansu province to the west and trends about s65 e this fault is very clear on landsat imagery and on aerial photos and the portion in eastern gansu and ningxia broke in the haiyuan earthquake of december 16 1920 displacements of 5 10 m caused by that earthquake are clear in numerous localities and accord with a revised value of the seismic moment of 1 2 1021n m the eastern end of the haiyuan fault terminates in a narrow south trending fold and thrust zone several other similar north to northwest trending fold and thrust belts are present in the area about 50 200 km northeast of the haiyuan fault and divide it into small apparently relatively undeformed blocks 10 40 km in dimensions the geometry of the structures in the fold and thrust zones and the apparently shallow depths at the time of deformation suggest that current deformation is similar to that that occurred in the fold and thrust belt of the idaho wyoming rocky mountains north of this area both the helan shan a horst and the yinchuan graben are bounded by clear active northerly trending normal faults in some cases with right lateral strike slip components the overall deformation hence seems to include dominant components of east west left lateral strike slip movement northeast southwest crustal shortening and northwest southeast extension we interpret the extension as a response to a northeast directed force applied to the ordos block and both this northeast directed force and the left lateral slip on the haiyuan fault to the eastward displacement of material on the northeast edge of the tibetan plateau with respect to eurasia north of it

present day crustal deformation in china constrained by global positioning system measurements global positioning system gps measurements in china indicate that crustal shortening accommodates most of india s penetration into eurasia deformation within the tibetan plateau and its margins the himalaya the altyn tagh and the qilian shan absorbs more than 90 of the relative motion between the indian and eurasian plates internal shortening of the tibetan plateau itself accounts for more than one third of the total convergence however the tibetan plateau south of the kunlun and ganzi mani faults is moving eastward relative to both india and eurasia this movement is accommodated through rotation of material around the eastern syntaxis the north china and south china blocks east of the tibetan plateau move coherently east southeastward at rates of 2 to 8 millimeters per year and 6 to 11 millimeters per year respectively with respect to the stable eurasia

magnetostratigraphic dating of the late miocene baogeda ula formation and associated fauna in central inner mongolia northern china abstract detailed understanding to the evolution of neogene land mammals in east asia and its intercontinental correlation has been impeded by the absence of an integrated biochronological system of this region the numerous and diverse records of neogene vertebrate fossils preserved in inner mongolia of northern china play a key role in the establishment of an independent biochronological framework in east asia however most of these faunas are poorly constrained by independent chronological controls due to the scattered distribution of fossil localities and insufficient exposure of the fossiliferous strata additionally age estimates by mammalian evolution and correlation often have uncertainties greater than 1 2 million years here we present new magnetostratigraphic results of the baogeda ula fauna which was generally assigned an early baodean age late miocene or equivalent to the european mn12 zone middle turolian hipparion remains and associated vertebrate fossils were excavated from the upper part of the fluvio lacustrine baogeda ula formation near abaga banner central inner mongolia of northern china at least two layers of basalt sheet flows can be observed on top of the baogeda ula formation our magnetostratigraphy aided by published biochronology data and k ar ages of the lower basalt layer suggests that the baogeda ula fauna consisting of three fossiliferous horizons can be placed within chron c4n 1n with an age range of 7 642 7 528 ma thus the baogeda ula fauna becomes the first and only baodean assemblage that is constrained by both magnetostratigraphy and radiometric ages offering an anchoring point for future biochronological correlations

magnitudes of large shallow earthquakes from 1904 to 1980 abstract in order to obtain a uniform magnitude catalogue surface wave magnitudes ms and broad band body wave magnitudes mb have been determined for large shallow earthquakes from 1904 to 1980 in making the catalogue homogeneous the author consistently adheres to the original definitions of ms and mb given by gutenberg 1945 and gutenberg and richter 1956 the determinations of ms and mb are all based on the amplitude and period data listed in gutenberg and richter s unpublished notes bulletins from stations worldwide and other basic information mb is measured on broad band instruments in periods of 8 s consistency of the magnitude determinations from these different sources is carefully checked in detail more than 900 shallow shocks of magnitude 7 and over are catalogued the meaning of the magnitude scales in various catalogues is examined in terms of ms and mb most of the magnitudes listed by gutenberg and richter 1954 in their seismicity of the earth are basically ms for large shocks shallower than 40 km but are basically mb for large shocks at depths of 40 60 km the surface wave magnitudes given by earthquake data reports are higher than ms by 0 2 unit whether the combined horizontal amplitude or the vertical amplitude is used mb and the currently used 1 s body wave magnitude are measured at different periods and should not be directly compared

hyposat an enhanced routine to locate seismic events a program package called hyposat has been under development that attempts to use the maximum information possible to estimate the hypocenter of a seismic source the standard input parameters can be used arrival times of first and later onsets with backazimuths and ray parameters or apparent velocities in addition travel time differences between different phases observed at the same station can be optionally used the observed standard deviations are used to weight all input parameters and the inversion is done with a generalized matrix inversion code

source process of the 1911 m8 0 chon kemin earthquake investigation results by analogue seismic records several destructive earthquakes have occurred in tien shan region at the beginning of 20th century however the detailed seismological characteristics especially source parameters of those earthquakes are still poorly investigated the chon kemin earthquake is the strongest instrumentally recorded earthquake in the tien shan region this earthquake has produced an approximately 200 km long system of surface ruptures along kemin chilik fault zone and killed about similar to 400 people several studies presented the different information on the earthquake epicentre location and magnitude and two different focal mechanisms were also published the reason for the limited knowledge of the source parameters for the chon kemin earthquake is the complexity of old analogue records processing digitization and analysis in this study the data from 23 seismic stations worldwide were collected and digitized the earthquake epicentre was relocated to 42 996na degrees and 77 367ea degrees the hypocentre depth is estimated between 10 and 20 km the magnitude was recalculated to m b 8 05 m s 7 94 and m w 8 02 the focal mechanism determined from amplitude ratios comparison of the observed and synthetic seismograms was str 264a degrees dip 52a degrees rake 98a degrees the apparent source time duration was between similar to 45 and similar to 70 s the maximum slip occurred 25 s after the beginning of the rupture two subevents were clearly detected from the waveforms with the scalar moment ratio between them of about 1 3 the third subevent was also detected with less certainty taking into account surface rupture information the fault geometry model with three patches was proposed based on scaling relations we conclude that the total rupture length was between similar to 260 and 300 km and a maximum rupture width could reach similar to 70 km

the 2013 balochistan earthquake an extraordinary or completely ordinary event the 2013 balochistan earthquake a predominantly strike slip event occurred on the arcuate hoshab fault in the eastern makran linking an area of mainly left lateral shear in the east to one of shortening in the west the difficulty of reconciling predominantly strike slip motion with this shortening has led to a wide range of unconventional kinematic and dynamic models here we determine the vertical component of motion on the fault using a 1 m resolution elevation model derived from postearthquake pleiades satellite imagery we find a constant local ratio of vertical to horizontal slip through multiple past earthquakes suggesting the kinematic style of the hoshab fault has remained constant throughout the late quaternary we also find evidence for active faulting on a series of nearby subparallel faults showing that failure in large distributed and rare earthquakes is the likely method of faulting across the eastern makran reconciling geodetic and long term records of strain accumulation

slip in the 1857 and earlier large earthquakes along the carrizo plain san andreas fault the moment magnitude mw 7 9 fort tejon earthquake of 1857 with a 350 kilometer long surface rupture was the most recent major earthquake along the south central san andreas fault california based on previous measurements of its surface slip distribution rupture along the 60 kilometer long carrizo segment was thought to control the recurrence of 1857 like earthquakes new high resolution topographic data show that the average slip along the carrizo segment during the 1857 event was 5 3 1 4 meters eliminating the core assumption for a linkage between carrizo segment rupture and recurrence of major earthquakes along the south central san andreas fault earthquake slip along the carrizo segment may recur in earthquake clusters with cumulative slip of 5 meters

historical seismograms for unravelling a mysterious earthquake the 1907 sumatra earthquake history of instrumental seismology is short seismograms are available only for a little more than 100 years high quality seismograms are available only for the last 50 years and the seismological database is very limited in time to extend the database seismograms of old events are of vital importance many unusual earthquakes are known to have occurred but their seismological characteristics are poorly known the 1907 sumatra earthquake is one of them 1907 january 4 m 7 6 gutenberg and richter located this event in the outer rise area of the sunda arc this earthquake is known to be anomalous because of its extensive tsunami which is disproportionate of its magnitude the tsunami affected the coastal areas over 950 km along the sumatran coast we investigated this earthquake using the historical seismograms we could collect from several seismological observatories we examined the p wave arrival times listed in the strassburg bulletin 1912 and other station bulletins the scatter of the observed computed traveltime residuals ranges from 30 to 30 s too large to locate the event accurately the uncertainty of the epicentre estimated from an s p grid search relocation study is at least 1 110 km we interpreted the omori seismograms from osaka mizusawa and tokyo and the wiechert seismograms from gottingen and uppsala by comparing them with the seismograms simulated from modern broad band seismograms of the 2002 2008 and two 2010 sumatra earthquakes which occurred near the 1907 earthquake from the amplitude of rayleigh waves recorded on the omori seismograms we conclude that the magnitude of the 1907 earthquake at about 30 to 40 s is about 7 8 i e 7 5 to 8 0 the sh waveforms recorded on the gottingen and uppsala seismograms suggest that the 1907 earthquake is a thrust earthquake at a shallow depth around 30 km the most likely scenario is that the 1907 earthquake initiated on the subduction interface and slowly ruptured up dip into the shallow sediments and caused the extensive tsunami although their quantity and quality are limited historical seismograms provide key quantitative information about old events that cannot be obtained otherwise this underscores the importance of preserving historical seismograms

co seismic thrusting rupture and slip distribution produced by the 2008 mw 7 9 wenchuan earthquake china field investigations reveal that the mw 7 9 wenchuan china earthquake of 12 may 2008 produced a 285 km long surface rupture zone with dominantly thrusting slip accompanied by a right lateral component along the central northern segments of the zone and left lateral component along the southern segment along the longmen shan thrust belt eastern margin of the tibetan plateau the co seismic ruptures mainly occurred along the pre existing yingxiu beichuan guanxian anxian and qingchuan faults which are the main faults of the longmen shan thrust belt the displacements measured in the field are approximately 0 5 6 5 m in the vertical typically 1 3 m accompanied by an average left lateral component of 2 m along the 50 km long southernmost segment of the rupture zone and an average right lateral component of 1 m along the 150 km long central northern segments the maximum thrust slip amount is estimated to be 10 m accompanied by 9 m of shortening across the rupture zone this finding is consistent with estimates based on seismic data the rupture length and maximum vertical displacement are the largest among all intracontinental thrust type earthquakes reported to date our findings demonstrate that i the wenchuan earthquake occurred upon pre existing active faults of the longmen shan thrust belt thereby controlling the spatial distribution of co seismic surface rupture and displacement and the rupture processes of the earthquake ii the long rupture length and large thrusting slip resulted from compressive stress associated with eastward extrusion of the tibet plateau as it accommodates the ongoing penetration of the indian plate into the eurasian plate and iii present day shortening strain upon the eastern margin of the tibetan plateau is mostly released by seismic slip along thrust faults within the longmen shan thrust belt

coseismic reverse and oblique slip surface faulting generated by the 2008 mw 7 9 wenchuan earthquake china the mw 7 9 wenchuan china earthquake ruptured two large thrust faults along the long menshan thrust belt at the eastern margin of the tibetan plateau this earthquake generated a 240 km long surface rupture zone along the beichuan fault and an additional 72 km long surface rupture zone along the pengguan fault maximum vertical and horizontal offsets of 6 5 m and 4 9 m respectively were measured along the beichuan fault a maximum vertical offset of 3 5 m was measured along the pengguan fault coseismic surface ruptures integrated with aftershocks and industry seismic profiles show that two imbricate structures have ruptured simultaneously resulting in the largest continental thrust event ever documented large oblique thrusting observed during this earthquake indicates that crustal shortening is an important process responsible for the high topography in the region as everywhere along the edge of tibetan plateau

late quaternary left lateral slip rate of the haiyuan fault northeastern margin of the tibetan plateau 1 slip rates of major active strike slip faults within and around the tibetan plateau provide constraints for understanding the dynamics of continental deformation in general because large slip rates can be taken to imply localized deformation between rigid blocks and low slip rates on faults are more consistent with distributed deformation several major strike slip faults have been studied during the last 3 decades as one of important active strike slip faults in and around the tibetan plateau the slip rate of the haiyuan fault has been discrepantly estimated to be high by proponents of escape tectonics or low by others and gps observations to better constrain its slip rate and then to better understand the mechanics of intracontinental deformation we try to more carefully consider offset geomorphic features and age constraints along the haiyuan fault in this paper we select three sites where both upper and lower bounds of slip rate can be obtained we find that slip rates are 4 2 0 8 mm yr at the shaomayin 4 5 0 7 mm yr at gaowanzi and 5 0 2 5 mm yr at huangliangtan site combinations of these rates with those published previously yield an average slip rate of 4 5 1 0 mm yr on the haiyuan fault this rate agrees with the present day slip rate of 4 3 1 5 mm yr measured by gps 4 2 8 mm yr by interferometric synthetic aperture radar and 5 mm yr through paleoseismological studies the temporal consistency suggests a steady state process of strain accumulation and release along the haiyuan fault the low slip rate suggests that the haiyuan fault similar to the altyn tagh fault does not transfer a significant portion of the convergence between india and asia out of india s path into eurasia but merely redistributes crustal thickening

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

the isc gem global instrumental earthquake catalogue 1900 2009 introduction abstract in this introductory article we give a general description of the isc gem global instrumental earthquake catalogue 1900 2009 we also provide the background for four further articles that describe the effort in collecting and digitizing parametric earthquake bulletin data as well as the methodologies developed to compute homogeneous earthquake parameters the result of the two and a half year project is a catalogue of approximately 20 000 large earthquakes covering 110 years with hypocentres and uncertainties computed using the same technique and velocity model we show that the overall homogeneity of the main earthquake parameters in the catalogue was achieved despite changes in instrumentation and routine measurement practices concurrent with developments in instrumental seismology from almost a ground level to its current state for each earthquake mw magnitude values and uncertainties were computed either based on available estimates of seismic moment or using new empirical relationships between mw ms and mb further important results of this project include the electronic availability of a considerable volume of seismic wave arrival time and amplitude measurements from early instrumental printed station bulletins these newly recovered amplitude measurements provided a basis for computation of many previously unavailable ms magnitudes with uncertainties in this article we describe why such a catalogue is required for a comprehensive assessment of global and regional seismic hazard we also describe other potential uses of the catalogue in many other fields of earth sciences we discuss the catalogue availability and lay out the plans of further development

source parameters and tectonic origin of the 1996 june 1 tianzhu mw 5 2 and 1995 july 21 yongden mw 5 6 earthquakes near the haiyuan fault gansu china summary the 1996 june 1 tianzhu mw 5 2 ms 4 9 and the 1995 july 21 yongden mw 5 6 ms 5 4 earthquakes are the two largest events recorded in the last 10 years between the 1990 october 20 ms 5 8 and the recent 2000 june 6 ms 5 6 earthquakes near the tianzhu seismic gap on the haiyuan fault in northeastern tibet we use frequency time analysis ftan to extract the fundamental modes of love and rayleigh waves from digital records a joint inversion of their amplitude spectra and of p wave first motion polarities is then performed to calculate the source parameters focal mechanisms depths and seismic moments of these two ms 5 earthquakes such a joint inversion is tested for the first time we use iris and geoscope network records for period ranges of 20 40 s for the former event and 35 70 s for the latter the inversion of the tianzhu earthquake yields nodal planes with strike dip and slip of 282 72 and 3 and 191 87 and 162 respectively a focal depth around 12 km and a seismic moment of 0 56 1017 n m consistent with the harvard cmt calculation and the alignment and depths of the aftershocks recorded by a local network we propose two possible tectonic interpretations for this off fault event the solution for the yongden earthquake is consistent with a thrust with strike dip and slip of 105 45 and 75 respectively a focal depth around 6 km and a seismic moment of 2 4 1017 n m also in agreement with the harvard cmt mechanism the distribution of the aftershocks recorded by a regional network and the general tectonic setting that we refine

variability in magnitude of paleoearthquakes revealed by trenching and historical records along the haiyuan fault china paleoseismology provides fundamental data for generalizing earthquake recurrence behavior by revealing past surface rupturing events determining the size of paleoseismic events is notoriously more challenging than their timing paleoearthquakes exposed in trenches are vaguely defined as large enough to break to the surface and often assumed to be similar in size here we show an example where the paleoseismic record includes events of both moderate and large magnitudes at the salt lake site on the active left lateral haiyuan fault northern tibetan plateau a high resolution stratigraphic sequence recorded three and possibly four events since a d 1500 constrained by accelerator mass spectrometry 14 c dating historical accounts of earthquake damage in the study region suggest that several earthquakes exposed in the trenches markedly differ in magnitude with the exception of the most recent m 8 earthquake that occurred in a d 1920 two earlier events which occurred in a d 1760 or 1709 and 1638 respectively are considerably smaller with magnitude m 7 and more likely m 6 or less thus this section of the haiyuan fault that broke during moderate magnitude events failed again after a short interval during a large m w 7 8 8 3 earthquake as part of a larger multisegment rupture our study shows that moderate magnitude events can be preserved in the stratigraphy and exposed by paleoseismic trenching under ideal conditions for instance if sedimentation is fast enough and there is no hiatus in deposition eventually the data presented add to the growing body of paleoseismic records containing events of different magnitudes with a large variability in rupture length and coseismic slip

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

displacement along the haiyuan fault associated with the great 1920 haiyuan china earthquake abstract we used a plane table and an alidade to construct detailed topographic maps of offset features stream channels dry gullies and old terrace walls along the fault zone that ruptured during the 1920 haiyuan earthquake m 8 7 in ningxia and gansu china the maximum displacement appears to have reached 10 m at shikaguangou between the salt lake and xianzhou basins in southern ningxia the average displacement along the 100 km of the fault that we studied was about 8 m assuming that the average slip rate to be between 5 and 10 mm yr the recurrence interval for events similar to that in 1920 would be about 800 to 1600 yr

high resolution satellite imagery mapping of the surface rupture and slip distribution of the mw 7 8 14 november 2001 kokoxili earthquake kunlun fault northern tibet china the mw 7 8 kokoxili earthquake of 14 november 2001 which ruptured a 450 km long stretch of the sinistral kunlun strike slip fault at the northeastern edge of the tibet plateau china ranks as the largest strike slip event ever recorded instrumentally in asia newly available high resolution satellite hrs images pixel size 1 m acquired in the months following the earthquake proved a powerful tool to complement field investigations and to produce the most accurate map to date of the coseismic displacements along the central kusai hu segment of the rupture the coseismic rupture geometry south and west of buka daban feng near the earthquake epicenter was also investigated in detail along the kusai hu segment slip parti tioning is for the first time observed to occur simultaneously during a single event with two parallel strands 2 km apart localizing almost pure strike slip and normal faulting in all 83 new hrs coseismic offset measurements some of which calibrated by field work show large well constrained variations 100 of the slip function over distances of only25 km tension cracks opening ahead of the shear dislocation and later offset by the upward propagating strike slip rupture were observed dem onstrating that the rupture front propagated faster at depth than near the surface the triple junction between the central kusai hu segment the kunlun pass fault where the rupture ended and the xidatan dongdatan segment which could be the next segment to fail along the main kunlun fault acted as a strong barrier implying that direct triggering of earthquake rupture on the xidatan dongdatan segment by kokoxili type earthquakes may not be the rule