slip rate measurements on the karakorum fault may imply secular variations in fault motion beryllium 10 surface exposure dating of offset moraines on one branch of the karakorum fault west of the gar basin yields a long term 140 to 20 thousand year right lateral slip rate of 10 7 0 7 millimeters per year this rate is 10 times larger than that inferred from recent insar analyses 1 3 millimeters per year that span 8 years and sample all branches of the fault the difference in slip rate determinations suggests that large rate fluctuations may exist over centennial or millennial time scales such fluctuations would be consistent with mechanical coupling between the seismogenic brittle creep and ductile shear sections of faults that reach deep into the crust

rate of slip from multiple quaternary dating methods and paleoseismic investigations along the talas fergana fault tectonic implications for the tien shan range the 400 km long talas fergana fault is one of a series of major right lateral strike slip faults that cross the tien shan range this fault has been recognized as active in the late holocene and accommodates part of the deformation induced by the ongoing indo asian collision the kinematics and the role of this strike slip fault are poorly understood with no large earthquakes reported in the instrumental or historical catalogs and no well constrained geological slip rate estimates here we used high resolution satellite imagery to present a first detailed analysis of the fault segmentation we identified nine geometric segments based on strike variations for the talas fergana fault along the kyldau segment through morphological analyses of an offset alluvial fan and the application of multiple dating methods be 10 al 26 cl 36 luminescence and radiocarbon we calculated a late quaternary slip rate ranging from 2 2 to 6 3 mm year this rate is higher than the geodetic measurements but the discrepancy can be partly explained if the talas fergana fault accommodates shortening by counterclockwise rotation around a vertical axis paleoearthquakes identified by trenching indicate that at least two primary surface ruptures and possibly a third occurred in the past 3 800 years and that no large earthquake has ruptured the kyldau segment since at least 420 years b p possibly within the last 2 700 years making this fault segment a potential candidate to generate an earthquake with m 7 in the near future

effects of prestress state and rupture velocity on dynamic fault branching 1 we consider a mode ii rupture which propagates along a planar main fault and encounters an intersection with a branching fault using an elastodynamic boundary integral equation formulation allowing the failure path to be dynamically self chosen we study the following questions does the rupture initiate along the branch does it continue is the extensional or compressional side most favored for branching does rupture continue on the main fault too failure is described by a slip weakening law for which the strength at any amount of slip is proportional to normal stress our results show that dynamic stresses around the rupture tip which increase with rupture velocity at locations off the main fault plane relative to those on it could initiate rupture on a branching fault as suggested by prior work whether branched rupture can be continued to a larger scale depends on principal stress directions in the prestress state and on rupture velocity the most favored side for branching rupture switches from the extensional to the compressional side as we consider progressively shallower angles of the direction of maximum compressive prestress with the main fault simultaneous rupturing on both faults can be activated when the branching angle is wide but is usually difficult for a narrow branching angle due to strong stress interactions between faults however it can be also be activated by enhanced dynamic stressing when the rupture velocity is very near the rayleigh velocity natural examples seem consistent with the simulations that we present

the 2002 denali fault and 2001 kunlun fault earthquakes complex rupture processes of two large strike slip events we studied the source processes of two large continental earthquakes the 3 november 2002 denali fault earthquake and the 14 november 2001 kunlun fault earthquake associated with strike slip faulting along ancient sutures we inverted teleseismic p waveforms using a pulse stripping method for multiple time windows with different focal mechanisms and derived composite source models according to our results the 2002 denali fault earthquake began with initial thrusting m w 7 3 along a 40 km long segment of the north northwest dipping susitna glacier fault and later ruptured a 300 km long segment along the denali and totschunda faults with a right lateral strike slip mechanism m w 7 7 in contrast the 2001 kunlun fault earthquake nucleated near an extensional step over with a subevent pair consisting of 30 km long strike slip m w 6 9 event and 40 km long normal m w 6 8 faulting event and later ruptured a 350 km long segment along the kunlun fault with a left lateral strike slip mechanism m w 7 7 both earthquakes propagated primarily unilaterally to the east and released most of their energy along slip patches asperities far from the hypocenter locations we find that both the denali fault and kunlun fault earthquakes had high average rupture velocities of 3 2 km sec and 3 4 km sec respectively we also compared the source properties of these two earthquakes with other strike slip earthquakes for scaling purposes large strike slip earthquakes were classified as interplate oceanic intraplate or continental intraplate events by using this classification the denali fault and kunlun fault earthquakes have an interplate signature that suggests overall weak faulting

uniform postglacial slip rate along the central 600 km of the kunlun fault tibet from 26al 10be and 14c dating of riser offsets and climatic origin of the regional morphology late pleistocene holocene sinistral slip rates on several segments of the kunlun fault in northeastern tibet have been determined these determinations are based on the measured displacement of alluvial surfaces whose surface ages were determined by cosmogenic 2 6 al and 1 0 be dating of quartz pebbles and by 1 4 c dating of charcoal in the west at three sites along the xidatan dongdatan segment of the fault near 94 e terrace riser offsets ranging from 24 to 110 m with cosmogenic ages ranging from 1800 to 8200 yr yield a mean left lateral slip rate of 11 7 1 5 mm yr 1 field observations indicate minimum offsets of 9 12 m this offset when combined with the long term slip rate indicates that great earthquakes m 8 rupture this segment of the fault with a recurrence interval of 800 1000 yr at two sites along the dongxi anyemaqin segment of the fault near 99 e terrace riser offsets ranging from 57 to 400 m with 1 4 c ages ranging from 5400 to 37 000 yr bp yield a minimum slip rate of 10 mm yr 1 at one site the 1937 january 7 m 7 5 and the penultimate earthquakes produced 4 m of left slip and 0 4 m of reverse slip the maximum recurrence interval of earthquakes with such characteristic slip is thus 400 yr farther east near 100 5 e along the maqen segment of the fault the 180 m offset of a lateral moraine emplaced between the last glacial maximum 20 ka and 11 100 yr bp yields a mean slip rate of 12 5 2 5 mm yr 1 the slip rates are constant within uncertainty throughout the 600 km of the kunlun fault that we studied the average slip rate is 11 5 2 0 mm yr 1 extrapolating this rate to the reminder of the fault we conclude that most 80 per cent of the 300 morphological offsets measured in the field or on spot satellite images post date the last glacial maximum most of the terraces we studied were deposited during the humid period of the early holocene optimum 9 5 ka the formation of younger terraces reflects late holocene climate change

dynamic slip transfer from the denali to totschunda faults alaska testing theory for fault branching we analyze the observed dynamic slip transfer from the denali to totschunda faults during the mw 7 9 3 november 2002 denali fault earthquake alaska this study adopts the theory and methodology of poliakov et al 2002 and kame et al 2003 in which it was shown that the propensity of the rupture path to follow a fault branch is determined by the preexisting stress state branch angle and incoming rupture velocity at the branch location here we check that theory on the denalitotschunda rupture process using 2d numerical simulations of processes in the vicinity of the branch junction the maximum compression direction with respect to the strike of the denali fault near the junction has been estimated to range from approximately 73 to 80 we use the values of 70 and 80 in our numerical simulations the rupture velocity at branching is not well constrained but has been estimated to average about 0 8 cs throughout the event we use 0 6 cs 0 8 cs 0 9 cs and even 1 4 cs as parameters in our simulations we simulate slip transfer by a 2d elastodynamic boundary integral equation model of mode ii slip weakening rupture with self chosen path along the branched fault system all our simulations except for 70 and 0 9 cs predict that the rupture path branches off along the totschunda fault without continuation along the denali fault in that exceptional case there is also continuation of rupture along the denali fault at a speed slower than that along the totschunda fault and with smaller slip

influences of continental monsoons and air sea coupling on the climate of the equatorial pacific abstract an air sea land coupled model of intermediate complexity was used to reveal the important roles of air sea coupling and adjacent continental monsoons i e american monsoons and asian australian monsoons on the annual cycle and mean state of the equatorial pacific excluding the effects of adjacent continental monsoons the simulated mean sst in the western pacific displays a warm bias the sst seasonal cycle exhibits an erroneous dominant annual component in the western pacific and insufficient strength and a 2 month phase delay in the equatorial eastern pacific the air sea coupling alone cannot sustain the full strength of the annual marches of the itcz cold tongue complex this is because the diabatic heating associated with the itcz rainfall generates both a southerly and a westerly component to its equatorward side while the southerly cools the cold tongue establishing a positive feedback to enhance the itcz and the equatorial westerly favors cold tongue warming inducing a negative fe

uniform slip rate along the kunlun fault implications for seismic behaviour and large scale tectonics a long term slip rate is derived from concordant 10 be 26 al and 14 c dating of cumulativeoffse ts along much of the length of the kunlun fault values at 6 sites indi cateuniform slip 11 5 2 0 mm yr since 40 kyr bp this relatively high slip rate corresponds to a first order discon tinuity in the asian crustal velocity field m 8a nd m 7 5 earthquakes on 2 segments of the fault recur with charac teristic slip 10 2ma nd 4 4 0 4m ev e ry 850 and 420 yrs respectively

slip partitioning by elastoplastic propagation of oblique slip at depth oblique motion along tectonic boundaries is commonly partitioned into slip on faults with different senses of motion the origin of slip partitioning is important to structural geology tectonophysics and earthquake mechanics partitioning can be explained by the upward elastoplastic propagation of oblique slip from a fault or shear zone at depth the strain field ahead of the propagating fault separates into zones of predominantly normal reverse and strike slip faulting the model successfully predicts the distribution of fault types along parts of the san andreas and haiyuan faults

normal and oblique slip of the 2008 yutian earthquake evidence for eastward block motion northern tibetan plateau abstract the 2008 yutian mw 7 1 earthquake occurred in a junction area of the altyn tagh karakax and kunlun fault systems and becomes a most northerly normal faulting event in the northern tibetan plateau high resolution satellite image interpretation and field investigation indicate that the surface rupture zone produced by the yutian earthquake is 31 km long along the yulong kashgar fault a ns trending fault at the western piedmont of a snow covered mountain at the headwater of the yulong kashgar river about 20 km south of the ashikule volcanoes the surface rupture zone along the yulong kashgar fault consists of four different types of surface ruptures with both normal and oblique slip components the maximum left lateral slip and vertical offset we measured in the field are 3 6 m and 3 3 m respectively this ns trending seismogenic fault belongs to one of the boundary faults between the qaidam qilian and the western kunlun blocks thus the yutian earthquake is as a result of abrupt normal and oblique slip faulting which fits the eastward escape of the qaidam qilian block relative to the western kunlun block this surface rupture pattern supports the eastward block like motion model whose deformation takes place mainly along the block boundaries delineated by mega strike slip faults in the northern tibetan plateau more important may be that the yutian earthquake has implication on future earthquake risk along the boundary faults of the qaidam qilian block

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

evidence of nonlinear elasticity of the crust from the mw7 6 manyi tibet earthquake satellite synthetic aperture radar sar interferometry shows that the magnitude 7 6 manyi earthquake of 8 november 1997 produced a 170 kilometer long surface break with up to 7 meters of left lateral slip reactivating a n76 e quaternary fault in western tibet the radar interferometric map reveals asymmetric along strike displacement profiles between the two sides of the surface rupture a pattern that cannot be explained with linear elastic theory this observation suggests that the elastic moduli of the crust in tension and in compression are different because of the presence of cracks in the crust at shallow depth a model indicates that a ratio of 2 between compressive and tensile elastic moduli can account for the observed asymmetry a ratio that is consistent with laboratory and borehole measurements

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

quaternary and active faulting observed on the 1985 academia sinica royal society geotraverse of tibet active and recent faulting along the main north south road in tibet is dominated by normal faulting occurring on northerly trending planes and by strike slip faulting both of which reflect an east west extension of the plateau normal faulting is prevalent in the southern half of the plateau but we saw no evidence for any major graben in the northern half strike slip faulting on roughly easterly trending structures is m ore prevalent in the northern half but conjugate faulting with right lateral slip on northwesterly trending planes and left lateral slip on northeasterly trending planes is common in the southern half in two areas we also observed components of thrust faulting apparently in association with young strikeslip faulting our most important results are bounds on the rates of slip on the two main strands of the kunlun strike slip fault system which trends east w est through the kunlun range ground moraine containing boulders of pyroxenite is separated by 30 km from the nearest outcrop of such rock implying that amount of displacement in the last 1 5 to 3 m a therefore the average rate of slip during the quaternary period has been between 10 and 20 mm a with a likely value of 13 mm a abundant fresh tension cracks and mole tracks imply continued slip on the main strand the xidatan tuosuohu maqu fault and the likely occurrence of a major earthquake in the last few hundred years consistent offsets of gullies and dry stream channels of about 10 m may reflect slip of that amount during such an earthquake and possible multiple offsets at one site suggest that slip may occur by large displacements of 10 m during infrequent great earthquakes along the other strand the kunlun pass fault offsets of roughly 50 to 150 m of apparently post glacial valleys and of one glacier and its terminal moraine suggest a holocene rate of slip between 5 and 20 mm a and most likely about 10 mm a on this fault these rapid rates of displacement imply that tibet is being extruded rapidly eastward at a rate com parable to the rate at which india is penetrating into eurasia and therefore that at present a substantial fraction of this penetration is being absorbed by the eastward extrusion of tibet

the 14 november 2001 kokoxili kunlunshan tibet earthquake rupture transfer through a large extensional step over the 14 november 2001 kokoxili tibet earthquake m w 7 8 ruptured 400 km of the western kunlun fault in northern tibet we apply two inversion methods to p and sh waves recorded by the global seismographic network to recover the spatial and temporal history of the rupture process the observed surface rupture consists of two strike slip segments offset by an extensional step over little surface rupture was observed in the graben system in this step over which is approximately 45 km long and over 10 km wide our results imply that the rupture did not jump this large gap but that the rupture was continuous through the graben the earthquake began with a small strike slip subevent presumably along the westernmost of the two segments this was followed 5 sec later by a subevent of about the same magnitude but having an oblique mechanism with a large normal faulting component the likely location for this subevent is within the graben this oblique slip event probably enabled transfer of the rupture onto the main kunlun fault the main moment release began 18 sec after rupture initiation and propagated over 350 km eastward along the kunlun fault slip on this segment was very heterogeneous averaging 2 m for the first 200 km followed by a sharp increase to a maximum of 7 5 m within the next 50 km and then a rapid decline the average rupture velocity along the main segment was high 3 6 km sec 1 and probably exceeded the local shear wave velocity the m w 7 8 kokoxili earthquake had a longer surface rupture and faster average rupture velocity radiated more energy and probably had a lower average fracture energy than the november 2002 m w 7 9 denali fault alaska earthquake evidence suggests that the velocity of the rupture front dropped significantly after passing the point of maximum slip implying a large difference in frictional strength between the two ends of the fault online material waveform fits to teleseismic body waves

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

millennial slip rates of the tazang fault the eastern termination of kunlun fault implications for strain partitioning in eastern tibet abstract the way of slip transformation and strain partitioning at the eastern termination of the kunlun fault system remains unclear and the question of whether this fault system is an important part for lateral extrusion of tibetan crust is debatable the tazang fault is regarded as the easternmost continuation of the kunlun fault system and its late quaternary activity is unknown in this paper we use displaced geomorphic features combined with radiocarbon and optically stimulated luminescence osl dating to determine millennial slip rates along the tazang fault our data yield a 1 4 3 2 mm yr left slip rate on the western tazang fault similar to that on the maqu segment of the kunlun fault tectonic geomorphology proposes that displacement on the kunlun fault is probably transferred to the tazang fault via a pull apart basin the eastern tazang fault has a dominant reverse motion that decreases eastward from 1 5 mm yr to 0 2 0 3 mm yr at the easternmost part displaced terraces indicate that the eastern strand of the northern longriba fault is active in the holocene and has a 0 8 mm yr right lateral slip rate with a 0 3 mm yr reverse component millennial slip rates and geodetic results show that the decrease of left lateral motion along the tazang fault is mainly transformed into crustal shortening along the nearly n s trending longriba minjiang and huya faults probably resulting in uplift of the min shan our results also indicate that the deformation along the tazang fault is not transferred to beyond the border of the plateau and the kunlun fault is not an important tectonics for tibetan extrusion

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

on and off fault deformation associated with the september 2013 mw 7 7 balochistan earthquake implications for geologic slip rate measurements abstract the 24 september 2013 mw7 7 balochistan pakistan earthquake ruptured a 200 km long stretch of the hoshab fault in southern pakistan and produced the second largest lateral surface displacement observed for a continental strike slip earthquake we remotely measured surface deformation associated with this event using high resolution 0 5 m pre and post event satellite optical imagery we document left lateral near field on fault offsets 10 m from fault using 309 laterally offset piercing points such as streams terrace risers and roads peak near field displacement is 13 6 2 5 3 4 m we characterize off fault deformation by measuring medium 350 m from fault displacement using manual 259 measurements and automated image cross correlation methods respectively off fault peak lateral displacement values are 15 m and exceed on fault displacement magnitudes for 85 of the rupture length our observations suggest that for this rupture coseismic surface displacement typically increases with distance away from the surface trace of the fault however nearly 100 of total surface displacement occurs within a few hundred meters of the primary fault trace furthermore off fault displacement accounts for on average 28 of the total displacement but exhibits a highly heterogeneous along strike pattern the best agreement between near field and far field displacements generally corresponds to the narrowest fault zone widths our analysis demonstrates significant and heterogeneous mismatches between on and off fault coseismic deformation and we conclude that this phenomenon should be considered in hazard models based on geologically determined on fault slip rates

quaternary extension in southern tibet field observations and tectonic implications we summarize evidence for quaternary and active faulting collected in the field during three sino french expeditions to southeastern tibet 1980 1982 detailed mapping of quaternary and active faults as well as microtectonic measurements indicate that normal faulting has been the dominant tectonic regime north of the himalayas in the last 2 0 5 m y the maximum horizontal principal stress in south tibet appears to be only the intermediate principal stress 2 1 being vertical south of the chord joining the eastern and western syntaxes of the himalayan arc extensional strains are principally localized within seven regularly spaced rift zones three of which have been studied in some detail the extension direction is determined to be n96 e 7 mainly from statistical averaging of strikes of newly formed normal faults throw rates on normal faults are evaluated for different time spans 2 0 5 m y 60 40 kyr and 10 2 kyr b p using structural and topographic reliefs as well as synglacial and postglacial vertical offsets the rate of quaternary extension is about 1 m y 1 along an 1100 km long ese traverse across south tibet this corresponds to a spreading rate of 1 0 6 cm yr this rate and the divergent horizontal projections of slip vectors of earthquakes along the himalayan front constrain the rate at which rigid india underthrusts southern tibet to be 2 1 cm yr although most of the normal faults appear to be independent of and nearly orthogonal to the e w mesozoic tertiary tectonic fabric the yadong gulu rift appears to be guided for over 130 km by the older oblique ne sw nyainqentanglha range and fault zones along it this reactivated zone is the most prominent left lateral strike slip fault system in se tibet excepting this zone and the vicinity of the se extremity of the karakorum fault quaternary strike slip faulting is rare in south tibet i e south of the chord between the syntaxes of the himalayan arc north of the chord the tectonic style is different there minor conjugate strike slip faulting is widespread and appears to control quaternary normal faulting which is more diffuse and subdued than in south tibet along the chord the presence of a major zone of active right lateral en echelon strike slip faults karakorum jiali fault zone probably reflects the greater facility of eastward extrusion in north central tibet in response to the northward push of india the eastern himalayan syntaxis may be an obstacle to such extrusion movements south of the chord

reinterpretation of the active faulting in central mongolia we present remote sensing and fi eld observations of an 350 km long east west left lateral strike slip fault the south hangay fault in the hangay mountains of central mongolia an area previously believed to be deforming solely by slip on scattered and randomly oriented normal faults the known dip slip faults are shown to be short segments introduced at bends in the much longer strike slip fault our observations show that the active faulting in the hangay mountains is consistent with the regional strain fi eld of mongolia and does not require as suggested in other studies that the faults result from stresses introduced by the locally elevated topography our observations help to defi ne the active tectonics of this important part of the india eurasia collision the south hangay strike slip fault is a potential source of large magnitude earthquakes and constitutes a previously unrecognized hazard in this part of mongolia

tomographic evidence for localized lithospheric shear along the altyn tagh fault seismic tomography across the altyn tagh fault at the north edge of the tibetan plateau reveals a low p wave velocity anomaly below the fault down to 140 kilometers this anomaly probably reflects strike slip shear in the lithosphere slip partitioning may also induce a wedge of crust from the tarim basin to plunge into the mantle

co seismic mole track structures produced by the 2001 ms 8 1 central kunlun earthquake china extensive co seismic mole track structures have been observed along a 400 km long surface rupture zone associated with the 2001 ms 8 1 central kunlun earthquake north tibet the mole track structures appear in an angular ridge pattern which resembles an angular triangle shaped frame and in a bulge pattern forming small flat hillocks the mole tracks are developed within alluvial fans river channels and bajada and form a linked array of structures along the rupture zone the angular ridge structures resulted from flexural slip folding and faulting of frozen alluvial deposits and surface ice whereas bulge type structures developed by squeezing up of unconsolidated to weakly consolidated alluvial sediments the mole tracks generally formed within the co seismic rupture zone due to contraction in the right bend and right stepover areas between sinistral shear faults and are controlled by the pre existing fault and fold structures along the left lateral strike slip kunlun fault

seismic evidence for stepwise thickening of the crust across the ne tibetan plateau we performed a receiver function analysis on teleseismic data recorded along two 550 km long profiles crossing the northeastern tibetan plateau results from time to depth migration grid search vp vs determination and simulated annealing inversion of waveforms reveal that the crust thickens from 50 km near the northern edge of the plateau to 80 km south of the jinsha suture in the qiang tang block crustal thickening occurs in staircase fashion with steps located beneath the main reactivated sutures the vp vs ratio close to the global continental average does not suggest widespread partial melting but rather a more usual separation between an upper felsic and a lower mafic part within the northeastern tibetan crust

oblique stepwise rise and growth of the tibet plateau two end member models of how the high elevations in tibet formed are i continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and ii time dependent localized shear between coherent lithospheric blocks recent studies of cenozoic deformation magmatism and seismic structure lend support to the latter since india collided with asia 55 million years ago the rise of the high tibetan plateau likely occurred in three main steps by successive growth and uplift of 300 to 500 kilometer wide crustal thrust wedges the crust thickened while the mantle decoupled beneath gently dipping shear zones did not sediment infilling bathtub like of dammed intermontane basins formed flat high plains at each step the existence of magmatic belts younging northward implies that slabs of asian mantle subducted one after another under ranges north of the himalayas subduction was oblique and accompanied by extrusion along the left lateral strike slip faults that slice tibet s east side these mechanisms akin to plate tectonics hidden by thickening crust with slip partitioning account for the dominant growth of the tibet plateau toward the east and northeast

structural analysis of the 1997 mw 7 5 manyi earthquake and the kinematics of the manyi fault central tibetan plateau abstract on 8th november 1997 the mw 7 5 manyi earthquake ruptured the left lateral strike slip manyi fault in the central tibetan plateau despite its large magnitude a comprehensive geological study on the co seismic surface rupture has not yet been reported so far here we reported on our new results of the co seismic surface ruptures and left lateral offsets caused by the earthquake based on detailed interpretation of recently acquired high resolution worldview and spot 5 images we recognized a primary 185 km long surface rupture that trends n80 e in consistence with previous results along the poorly developed segment at the eastern end of the manyi fault a new rupture is also identified which trends n57 e and extends 17 km the co seismic surface rupture zone exhibits many distinct features such as stepovers extensional cracks ponds restraining and releasing bends in relation to fault geometrical complexities by visual analysis of the displaced geomorphic features using satellite imagery we measured 198 co seismic offsets along the 200 km fault trace the results show a 3 7 m average offset and a maximum offset of up to 7 5 m near the epicenter area the newly found 17 km long rupture is interpreted to be linked to the main fault during the event if the manyi fault continues this northeastward propagation for additional 100 km it will separate the bayanhar block into two sub blocks such a new hypothetical block model will influence assessment of seismic potential near the block boundaries and estimate of deformation of the bayanhar block and the central tibetan plateau

paleoseismic evidence of characteristic slip on the western segment of the north anatolian fault turkey we have conducted a paleoseismic investigation of serial fault rupture at one site along the 110 km rupture of the north anatolian fault that produced the mw 7 4 earthquake of 17 august 1999 the benefit of using a recent rupture to compare serial ruptures lies in the fact that the location magnitude and slip vector of the most recent event are all very well documented we wished to determine whether or not the previous few ruptures of the fault were similar to the recent one we chose a site at a step over between two major strike slip traces where the principal fault is a normal fault our two excavations across the 1999 rupture reveal fluvial sands and gravels with two colluvial wedges related to previous earthquakes each wedge is about 0 8 m thick considering the processes of collapse and subsequent diffusion that are responsible for the formation of a colluvial wedge we suggest that the two paleoscarps were similar in height to the 1999 scarp this similarity supports the concept of characteristic slip at least for this location along the fault accelerator mass spectrometry ams radiocarbon dates of 16 charcoal samples are consistent with the interpretation that these two paleoscarps formed during large historical events in 1509 and 1719 if this is correct the most recent three ruptures at the site have occurred at 210 and 280 year intervals

infrasonic imaging of the kunlun mountains for the great 2001 china earthquake 1 on november 14 2001 a strong earthquake occurred on the high plateau of western china at a distance of 1800 km from the epicenter coherent infrasonic waves were detected for more than one hour using both an inverse location procedure and a complete simulation of the radiated pressure field distant source regions are accurately located the seismo acoustic coupling along a mountain belt is clearly demonstrated such an event offers an opportunity to validate velocity models in the atmosphere as well as to improve the understanding of the amplification of ground displacement caused by the topography

dynamic modeling of the 1992 landers earthquake we have used observed band pass filtered accelerograms and a previously determined slip distribution to invert for the dynamic rupture propagation of the 1992 landers earthquake in our simulations dynamic rupture grows under the simultaneous control of initial stress and rupture resistance by friction which we modeled using a simple slip weakening law we used a simplified landers fault model where the fault segments were combined into a single vertical planar fault by trial and error we modified an initial stress field inferred from the kinematic slip distribution proposed by wald and heaton 1994 until dynamic rupture generated a rupture history and final slip distribution that approximately matched those determined by the kinematic inversion we found that rupture propagation was extremely sensitive to small changes in the distribution of prestress and that a delicate balance with energy release rate controls the average rupture speed for the inversion we generated synthetic 0 5 hz ground displacements using an efficient green s function propagator method axitra this method enables us to propagate the radiation generated by the dynamic rupture to distances greater than those feasible using the finite difference method the dynamic model built by trial and error inversion provides a very satisfactory fit between synthetics and strong motion data we validated this model using records from stations used in the slip inversion as well as some which were not included we also inverted for a complementary model that fits the data just as well but in which the initial stress was perfectly uniform while rupture resistance was heterogeneous this demonstrates that inversion of ground motion is nonunique

surface ruptures associated with the 1937 m 7 5 tuosuo lake and the 1963 m 7 0 alake lake earthquakes and the paleoseismicity along the tuosuo lake segment of the kunlun fault northern tibet examination of aerial photos taken in the late 1960s and field mapping allowed us to re evaluate the surface ruptures associated with the 1937 m 7 5 tuosuo lake and 1963 m 7 0 alake lake earthquakes along the tuosuo lake and alake lake segments central part of the kunlun fault individual ruptures can be distinguished by their freshness of surface expression slip distributions and surficial geometry they are separated by the geometrical bend that probably acts as an effective barrier to rupture propagation of these earthquakes the rupture 40 km long with 1 2 m left lateral slip of the 1963 alake lake earthquake occurred on the west of the bend whereas that of the 1937 tuosuo lake earthquake about 150 km long with 4 1 m mean left lateral offset occurred on the east of the bend the change of dip slip sense reflects the characteristics of jogs and bends along the segment boundaries systematically and progressively displaced terrace risers and gullies indicate repeated activity of the fault during the late quaternary five trenches excavated across the surface ruptures along the tuosuo lake segment reveal distinct indicators of paleoseismic events at least nine earthquakes are constrained in the holocene deposits and a 630 130 yr upper bound recurrence interval of large earthquakes in the past 2000 years is determined

rupture segmentation and process of the 2001 mw 7 8 central kunlun china earthquake field investigations allow us to constrain the coseismic surface rupture zone of 400 km with a strike slip up to 16 3 m associated with the 2001 m w 7 8 central kunlun earthquake that occurred along one of the western segments of the kunlun fault northern tibet the rupture zone may be divided into four segments based on the geological structures tectonic landform features spatial displacement distributions obtained from field observations and analysis of teleseismic waveforms the deformational characteristics of the surface ruptures and focal mechanism solutions reveal that the earthquake had a nearly pure strike slip mechanism the inversion results from seismic data show that the rupture started from the west near the epicentral area bilaterally and rapidly extended to the east in an unilateral manner for 380 km and that the largest slip region was limited in the subsegment 150 280 km east of the epicenter consistent with field observations the average stress drop is estimated to be 7 mpa in the area where the largest displacements occurred a value typical of intraplate earthquakes the geologic evidence and the inversion results from seismic data clearly show that temporal and spatial displacement distributions and the rupture process are restricted by the pre existing geological structures of the kunlun fault

the aftershock signature of supershear earthquakes recent studies show that earthquake faults may rupture at speeds exceeding the shear wave velocity of rocks this supershear rupture produces in the ground a seismic shock wave similar to the sonic boom produced by a supersonic airplane this shock wave may increase the destruction caused by the earthquake we report that supershear earthquakes are characterized by a specific pattern of aftershocks the fault plane itself is remarkably quiet whereas aftershocks cluster off the fault on secondary structures that are activated by the supershear rupture the post earthquake quiescence of the fault shows that friction is relatively uniform over supershear segments whereas the activation of off fault structures is explained by the shock wave radiation which produces high stresses over a wide zone surrounding the fault

faulting characteristics of supershear earthquakes article i nfo recent observations of large continental strike slip earthquakes show that different fault segments may rupture at different speeds and that rupture may propagate faster than the shear wave velocity of surrounding rocks we report that all the documented occurrences of supershear rupture are associated with faults which have simple geometry the surface trace of these faults is described in the field or seen on satellite images as remarkably linear continuous and narrow segmentation features along these segments are small or absent and the deformation is highly localized as theoretically predicted supershear is clearly associated with mode ii rupture

recovering paleoearthquake slip record in a highly dynamic alluvial and tectonic region hope fault new zealand from airborne lidar knowing the slip amplitudes that large earthquakes produced in prehistorical times is one key to anticipate the magnitude of large forthcoming events it is long known that the morphology is preserving remnants of paleoearthquake slips in the form of fault offset landforms however the measured offsets that can be attributed to the most recent paleoearthquakes are generally few along a fault so that they rarely allow recovering the slip distributions and largest slips of these earthquakes we acquired 1 m resolution airborne lidar data on a 30 km stretch of a fast slipping strike slip fault eastern hope fault new zealand located in a region of high alluvial dynamics where landforms are rapidly evolving data analysis reveals 200 offset landforms only 30 allow a good to moderate quality offset measurement from these good to moderate quality measures we recover the slip length distributions and largest slips of the four most recent large paleoearthquakes and find evidence of 4 6 prior events the record suggests that large earthquake slip recurred in multiples of about 4 m along the 30 km stretch although they have larger uncertainties the more numerous lower quality offsets that we also measured reveal a similar earthquake slip record this shows that although offset landforms are partly degraded in dynamically active landscapes they store valuable information on paleoearthquake slips this information might be recovered provided that the morphology is analyzed at high resolution and continuously over a significant fault length remote lidar data are powerful to perform such analyses

rapid slip along the central altyn tagh fault morphochronologic evidence from cherchen he and sulamu tagh consistent with the d 18 o record from the guliya ice cap in the west kunlun the features of interest were all formed by glacial and fluvial processes subsequent to marine isotope stage 5e with the youngest features having formed during the early holocene optimum this near field morphochronological slip rate is averaged over many earthquake cycles and is hence little affected by interseismic strain it is kinematically consistent with other somewhat lower geomorphic slip rate measurements to the east the average rate and lower bounds obtained from alternate interpretational models 18 4 mm yr cannot be reconciled with the most rece geodetic measurements 7 mm yr suggesting that interseismic strain and interactions with adjacent faults may lead to disparate geologic and geodetic rate estimates this late pleistocene holocene morphochronologic rate would imply that at this longitude the altyn tagh fault on the north edge of tibet might absorb almost as much of india s convergence relative to siberia as the himalayan main frontal thrust does on the southern edge of the plateau index terms 1035 geochemistry geochronology 1208 geodesy and gravity crustal movements intraplate 8110 8102 tectonophysics continental contractional orogenic belts 8107 tectonophysics continental neotectonics keywords slip rates cosmogenic dating indo asian collision

late cenozoic right lateral strike slip faulting in southern tibet field observations collected during the sino french himalaya tibet cooperation project 1980 1982 show that right lateral faulting between southern and northern tibet roughly along the chord joining the eastern and western syntaxes of the himalayan arc is a major component of the active tectonics north of the himalayas just north of the well developed rifts of southern tibet we studied three right lateral 100 200 km long strike slip faults forming an en echelon array along that chord evidence for earthquake surface breaks was found on each of these faults for the m 8 beng co or damxung strike slip earthquake of november 18 1951 rupture parameters could be constrained to be 8 2 m and l 90 km offset glacial and postglacial morphological markers 105 years and 104 years b p imply displacement rates of the order of 1 2 cm yr on the three faults the en echelon fault zone appears to extend westward 2000 km across the plateau to the karakorum fault and is thus referred to as the karakorum jiali fault zone kjfz fast rates of slip on it and on faults along the northern rim of tibet appear to contrast with the slower rates of deformations in the interior of the plateau our estimates of slip rates on the strike slip and normal faults of southeastern tibet suggest that eastward extrusion of north tibet between the right lateral kjfz and the left lateral altyn tagh and kun lun faults absorbs at least 30 of the present convergence between india and asia we propose an instantaneous velocity model of the active tectonics of asia compatible with such faulting rates and geometries evidence for tertiary right lateral strike slip movements in southern tibet and around the eastern syntaxis of the himalayas is also found in the structural record offsets of various large scale geological features imply that these movements have been large

broadband source modeling of the november 8 1997 tibet mw 7 5 earthquake and its tectonic implications we studied the source process of a large ms 7 9 intraplate earthquake that occurred on november 8 1997 at 1002 ut in a remote region of northern tibet we used four distinct methods to investigate the broadband source process and thereby better understand the tectonic implications of this event we relocated aftershocks using a master event technique and found that the distribution of aftershocks covers a region of 200 km in lateral extent we also employed a surface wave spectral inversion technique to estimate the mainshock moment depth centroid location and centroid time and utilized an empirical green s function technique to extract rupture directivity information and a detailed source time function from observed seismograms we also inverted body waves to estimate the moment release along the fault and the source time function the 1997 earthquake ruptured a strike slip fault that appears to be an extension or splay of the kun lun fault system this fault is one of the most seismically active strike slip faults within the tibetan plateau and has had events with surface wave magnitudes of 6 1 7 4 and 7 9 in this region since 1973 the rupture released most of the energy within the first 20 s and propagated bilaterally initially with the later rupture propagating westward for 20 30 s the absence of large aftershocks suggests that the earthquake efficiently released the stored strain comparing mainshock to the largest aftershock energy ratios for this event and other large strike slip events shows that faulting within the plateau has the characteristics of weak faults e g fracture zone faulting

teleseismic imaging of subducting lithosphere and moho offsets beneath western tibet teleseismic images suggest that the tarim plate plunges 45 s down to 300 km depth beneath nw tibet the 410 km discontinuity shallows by 10 km under the plateau implying 100 c cooler upper mantle the deepest moho on record 90 km lies under w qiangtang it rises abruptly by 20 and 10 km beneath the altyn tagh fault and bangong suture respectively vp vs ratios are normal except in the yecheng flexural basin and deep under the south karakax volcanics 1 92 w kunlun s neogene tectonics are simply accounted for by oblique subduction of lithospheric mantle beneath an upward extruding thrust wedge of the tarim crust

co seismic deformation and post glacial slip rate along the magallanes fagnano fault tierra del fuego argentina fil roy sandrine centre national de la recherche scientifique francia universite savoie mont blanc francia

co seismic strike slip and rupture length produced by the 2001 ms 8 1 central kunlun earthquake field investigations show that the surface wave magnitude ms 8 1 central kunlun earthquake tibetan plateau of 14 november 2001 produced a nearly 400 kilometer long surface rupture zone with as much as 16 3 meters of left lateral strike slip along the active kunlun fault in northern tibet the rupture length and maximum displacement are the largest among the co seismic surface rupture zones reported on so far the strike slip motion and the large rupture length generated by the earthquake indicate that the kunlun fault partitions its deformation into an eastward extrusion of tibet to accommodate the continuing penetration of the indian plate into the eurasian plate

field study of a highly active fault zone the xianshuihe fault of southwestern china the xianshuihe fault of western sichuan province china is one of the world s most active faults having produced 4 earthquakes during this century of magnitude 7 along a 350 km length of the fault at least 8 such events have occurred since 1725 in the more limited 150 km long segment including luhuo and daofu major earthquakes in 1904 1923 1973 and 1981 m 7 7 7 6 6 9 were associated with overlapping surficial fault ruptures and with individual left lateral displacements as large as 3 6 m field studies indicate that this high degree of activity is typical of the fault s longer term history the holocene left lateral slip rate on the north western segment of the fault has been 15 5 mm yr decreasing to about 5 mm yr on its southeastern segment based on radiometrically dated offset stream channel and terrace deposits and on offset glacial moraines physiographic features of active faulting are fully as diagrammatic as those of california s san andreas fault mainly because of high altitude preservation and the absence of cultural modification on this eastern margin of the tibetan plateau detailed en echelon tensional and pushup features resulting from surface ruptures in 1973 1955 1923 and 1893 can still be recognized today and new data have been collected bearing on the offsets and fault rupture lengths during these and other events the locations and magnitudes of historic earthquakes suggest that the characteristic earthquake model may apply to the xianshuihe fault obvious geometric segmentation of the fault has controlled the initiation and termination of ruptures in some events whereas segmentation control for others remains obscure based on the historic record repeat times estimated from slip rates and current seismic gaps two segments are particularly likely sites for m 7 earthquakes in the near future the 65 km long segment between daofu and qianning and the 135 km long segment bracketing kangding continuing creep has been documented along some segments of the fault and this together with the high degree of activity and other unique attributes makes the xianshuihe fault one of the most promising sites in the world for earthquake prediction and hazard evaluation studies

holocene left slip rate determined by cosmogenic surface dating on the xidatan segment of the kunlun fault qinghai china cosmogenic dating using in situ sup 26 al and sup 10 be in quartz pebbles from alluvial terrace surfaces constrains the late holocene slip rate on the xidatan segment of the kunlun fault in northeastern tibet two terrace risers offset by 24 3 and 33 4 m having respective ages of 1799 388 and 2914 471 yr imply a slip rate of 12 1 2 6 mm yr the full range of ages obtained le 22 8 k y most of them between 6 7 and 1 4 k y confirm that terrace deposition and incision hence landform evolution are modulated by post glacial climate change coupled with minimum offsets of 9 12 m this slip rate implies that great earthquakes m approximately 8 with a recurrence time of 800 1000 yr rupture the kunlun fault near 94 e

surficial slip distribution on the central emerson fault during the june 28 1992 landers earthquake california we present the results of our mapping of a 5 6 km length of the central emerson fault that ruptured during the 1992 landers earthquake in the southwestern mojave desert california the right lateral slip along this portion of the rupture varied from about 150 to 530 cm along the main rupture zone in some locations a total of up to 110 cm of additional right lateral slip occurred on secondary faults up to 1 7 km away from the main rupture zone other secondary faults carried up to several tens of centimeters of left lateral or thrust displacement the maximum net vertical displacement was 175 cm east side up the sense of vertical slip across the main fault zone varied along strike but in most cases it was consistent with the sense of vertical slip in previous earthquakes as indicated by the locations of areas of older uplifted and abandoned alluvial fan surfaces although variations in surficial slip have been reported along previous strike slip ruptures our closely spaced slip measurements allow a much more detailed study of slip variability than was possible previously we document variations in slip as large as 1 m or more over distances ranging from 1 2 km to a few tens of meters suggesting that strains of the order of 10 1 may have occurred locally within the surficial sediments the long wavelength kilometer scale variations in surficial slip may be influenced by fault geometry and perhaps by the thickness of unconsolidated sediments the slip variations over shorter length scales tens of meters may be caused by variations in the proportion of the total shear that occurs on visible brittle fractures versus that which occurs as distributed shear warping or rotation the variability of slip along the ruptures associated with the landers earthquake calls for caution in interpreting geomorphic offsets along prehistoric fault ruptures

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

illuminating the near sonic rupture velocities of the intracontinental kokoxili mw 7 8 and denali fault mw 7 9 strike slip earthquakes with global p wave back projection imaging 1 the denali and kokoxili strike slip earthquakes are two of the longest recent intracontinental ruptures previous studies report a range of rupture velocities here we image these earthquakes by reverse time migration of the intermediate frequency p wave train recorded by global broadband seismometers this technique permits a relatively direct measure of rupture velocity speed and direction as constrained by the radiated seismic energy free from restrictive assumptions or rupture speed bounds placed on the solution we compare our results with published seismic gps displacement and surface slip inversion results both ruptures were initially subshear and transitioned over a distance no longer than 40 km to supershear speeds close to the p wave speed of 5 6 km s we investigate the accuracy of our results with synthetic data and experiment with using different imaging parameters and seismic subnetworks these tests allow us to rule out the possibility of subshear speeds along the supershear segments although we cannot exclude supershear speeds of 4 5 6 5 km s our most reliable rupture velocities of 5 6 km s are close to the local p wave speeds we hypothesize that these intracontinental faults have weak shear strengths or high breakdown slips or crustal rigidities and experience at least moderate slip or slip rate weakening our observations and previous published results lead us to speculate that very long surface extending faults with general homogeneity in prestress and fault strength together with smaller adjacent fault segments to provide triggering may be necessary ingredients for the sub rayleigh to supershear rupture speed transition in strike slip earthquakes

characteristics geometry and segmentation of the surface rupture associated with the 14 april 2010 yushu earthquake eastern tibet china on the morning of 14 april 2010 the m s 7 1 yushu earthquake struck the eastern tibet plateau and an m s 6 3 aftershock followed west southwest of the mainshock epicenter one and a half hours later the yushu earthquake occurred on the northwestern continuation of the ganzi xianshuihe fault zone and reactivated two segments of the fault ruptures associated with yushu earthquake span a zone 70 km long extending from south of jielong in the west to south of gyegu yushu in the east detailed mapping of the surface rupture zone shows that it consists of two strike slip segments the western and eastern segments separated by the longbao lake step over pull apart basin our analysis suggests that the 18 km long western segment of the surface rupture south of the longbao lake basin may have been associated with the m s 6 3 aftershock the eastern rupture segment which is inferred to be associated with the mainshock is 32 km long the main surface rupture can also be divided into two sections with a 2 km long gap between them the surface rupture exhibits left lateral slip and is localized in a zone about 50 m wide along the present day trace of the yushu fault a single break without splays or branching traces characterizes most of the surface rupture zone the observed magnitudes of surface displacement are typically 0 5 1 m with a maximum slip of 2 m both field observations and seismic inversion results suggest rupture of m s 7 1 yushu earthquake nucleated near the longbao lake step over basin in the west propagated unilaterally eastward and terminated within the east segment margin of the yushu fault

slip rate on the kunlun fault at hongshui gou and recurrence time of great events comparable to the 14 11 2001 mw 7 9 kokoxili earthquake abstract a field study of the surface rupture of the 14 november 2001 mw 7 9 kokoxili or kunlun shan earthquake near hongshui gou 35 9 n 92 2 e a site with exceptional geomorphic offsets long identified on spot images yields bounds on this earthquake return time and on the slip rate along the kusai hu segment of the kunlun fault measurements of the sinistral coseismic and cumulative offsets of four distinct strath terrace risers and of rill channels incised in the adjacent fan bajada complemented by post earthquake metric resolution satellite image restoration are 3 0 5 m 6 1 m 31 2 m 63 5 m and 110 10 m the smallest offset is unambiguously that of the 14 11 2001 earthquake the 31 and 63 m riser offsets which have thermoluminescence ages of 2885 285 and 5960 450 yr respectively imply an average slip rate of 10 0 1 5 mm yr almost identical to that found 200 km eastwards in xidatan using 10 be cosmogenic dating of surface pebbles the repetitive seismic slip 3 m implies an average recurrence time of 300 50 yrs for earthquakes comparable to the 14 11 2001 event this new data increases the body of evidence suggestive of local characteristic slip during large earthquakes and firmly corroborates the millennial eastward extrusion rate 1 cm yr of north central tibet relative to the qaidam

geologic mapping of the chaac camaxtli region of io from galileo imaging data 1 we produced a geologic geomorphologic map of the chaac camaxtli region of io s leading anti jovian hemisphere using regional resolution 186 m pixel galileo imaging data collected during orbit i27 february 2000 integrated with lower resolution 1 4 km pixel color data along with other galileo imaging and spectral data this is the first regional map of io made from galileo data nine color and geomorphologic units have been mapped and the close proximity of dark and various colored bright materials suggests that there is an intimate interaction between presumably silicate magmas and sulfur bearing volatile materials that produced a variety of explosive and effusive deposits in the recent geologic past this region of io is dominated by 11 volcanic centers most of which are paterae that are analogous in morphology to terrestrial calderas but larger in size mapping of structural features indicates that most of the active regions occur in topographic lows and less active or inactive paterae are associated with topographic highs this indicates that crustal thickness variations influence magma access to the surface surface changes in this region since the voyager flybys 1979 are relatively minor additional bright and dark flows color changes although several active vents have migrated within paterae this observation along with the identification of the relatively regular spacing of paterae 100 150 km along a line may indicate there are multiple interlacing fractures in the crust that serve as magma conduits from the interior this connection between volcanism and tectonism may have implications for tidal heating mechanisms and their effect on io s lithosphere some inactive patera floors may be evolving into bright plains material which if composed of silicates might explain the strength of io s crust to support steep patera walls and tall mountains

dogtails versus rainbows synthetic earthquake rupture models as an aid in interpreting geological data geologists have been collecting for decades information from historical and paleoearthquakes that could contribute to the formulation of a big picture of the earthquake engine observations of large earthquake ruptures unfortunately are always going to be spotty in space and time so the extent to which geological information succeeds in contributing to a grander view of earthquakes is going to be borne not only by the quantity and quality of data collected but also by the means by which it is interpreted this article tries to understand geological data more fully through carefully tailored computer simulations of fault ruptures dogtails and rainbows are two types of fault rupture terminations that can be recognized in the field and can be interpreted through these models rainbows are concave down ruptures that indicate complete stress drop and characteristic slip rainbow terminations usually coincide with fault ends or strong segment boundaries dogtails are concave up ruptures that indicate incomplete stress drop and noncharacteristic slip dogtail terminations can happen anywhere along a fault or fault segment the surface slip pattern of the magnitude 6 6 1979 imperial valley california earthquake shows both dogtail and rainbow terminations the rainbow confirms the presence of a strong fault segment boundary 6 km north of the international border that had been suggested by sieh 1996 the dogtail implies that the displacement observed in 1979 is not characteristic by combining paleoseismic information with the surface slip patterns from this event and the magnitude 7 1 1940 imperial valley earthquake i develop a quantitative imperial fault model with northern central and southern segments possessing 50 110 and 50 bar strength respectively both the 1940 and 1979 events caused 1 m amplitude dogtailed ruptures of the northern segment however characteristic slip of the segment is more likely to be about 3 m to illustrate the full spectrum of potential rupture modes models were run forward in time to generate a 2000 year rupture encyclopedia even with well constrained segmentation and strengths modest changes in two friction law parameters produce several plausible histories further discrimination awaits analysis of the extensive paleoseismic record that geologists believe exists in the shore deposits of the intermittent lakes of the salton trough

dynamic shear rupture interactions with fault bends and off axis secondary faulting 1 on the basis of elastodynamic stress fields for singular crack and nonsingular slip weakening models of propagating rupture we develop preliminary answers to such questions as follows if a rupturing fault is intersected by another providing a possible bend in the failure path when will stressing be consistent with rupture along the bend what secondary fault locations and orientations in a damaged region bordering a major fault will be stressed to failure by the main rupture stresses that could initiate rupture on a bend are shown to increase dramatically with crack speed especially near the limiting speed rayleigh for mode ii shear for mode iii whether a bend path once begun can be continued to larger scales depends on principal stress directions and ratios in the prestress field conditions should often be met in mode ii for which bend paths encouraged by stressing very near the rupture tip are discouraged by the larger scale stressing a basis for intermittent rupture propagation and spontaneous arrest secondary failure in the damage zone likewise increases markedly as the limiting speed is approached such may make the fracture energy much greater than for slip on a single surface the extent of secondary faulting is strongly affected by prestress directions and the ratio of residual to peak strength for mode ii prestress controls whether activation occurs primarily on the extensional side which we show to be the typical case or on the compressional side too natural examples are consistent with the concepts developed

polyphase structural deformation of low to medium grade metamorphic rocks of the liaohe group in the jiao liao ji orogenic belt north china craton correlations with tectonic evolution abstract the paleoproterozoic jiao liao ji orogenic belt in the eastern north china craton provides evidence of the evolution from the early rifting and ocean opening to the final collision of the longgang and nangrim blocks however it is still open to debate and thus controversial as to whether the jiao liao ji orogenic belt formed by closure of a rift without subduction or from an ocean with subduction based on detailed field mapping and structural analysis on a micro meso scale of the liaohe group in the center of the orogenic belt we define at least four phases of deformation and metamorphism s 0 is bedding formed during deposition of the lower liaohe sediments in the liaohe back arc basin during d 1 deformation an early greenschist facies event m 1 was associated with a bedding parallel s 1 metamorphic foliation penetrative axial planar foliation micro to meso scale folds f 1 and an l 1 lineation all formed during accretion probably in a trench subduction setting an m 2 metamorphism took place during medium pressure barrovian type amphibolite facies conditions and associated d 2 deformation that gave rise to major thrusts open isoclinal folds and a well developed crenulation cleavage during exhumation of high pressure and high temperature rocks and collision of the longgang and nangrim blocks m 3 metamorphism at sillimanite m 3 1 and cordierite m 3 2 grade was associated with d 3 deformation that produced regional gentle re folds related to post collisional exhumation of the orogenic belt an m 4 retrograde metamorphism and d 4 deformation gave rise to a weak foliation that can be correlated with late cretaceous extension that affected the whole eastern north china craton we present new isotopic ages la icpms u pb zircon of a granitic vein 2162 ma a pegmatite 1840 ma and a very late granite 114 ma that are integrated with relevant published data accordingly the formation age of deformation and metamorphism was set up and at last a modified tectonic model was presented

broadscale postseismic deformation and lower crustal relaxation in the central bayankala block central tibetan plateau observed using insar data abstract we have generated a more than 500 km long postseismic deformation rate map and cumulative displacement time series in the central bayankala block of the tibetan plateau using envisat asar data from 2003 to 2010 by the rate stacking algorithm this rate map spans a period of 7 2 years and reveals that postseismic motion of 2001 kokoxili earthquake exhibits a striking signal dominating crustal deformation of the central bayankala block with a cross fault magnitude 9 11 mm yr in line of sight los 93 1 e the southern and northern parts of the postseismic deformation field exhibit different patterns and variable magnitudes reflecting asymmetry of the displacement distribution postseismic motion affects eastward extrusion of the central bayankala block which reaches 15 km north of the ganzi yushu fault to further investigate viscoelastic relaxation of the lower crust in this area after approximately two years e m e m m and e s models are constructed the result shows that the best fit viscosity for the lower crust is about 1 1019 pa s comparison between cumulative displacements resolved by these three models shows that viscoelastic relaxation of the lower crust makes the most significant contribution to postseismic stress relaxation after 2001 event

six similar sequential ruptures of the san andreas fault carrizo plain california we document the precise sizes but not the dates of the six latest offsets across the san andreas fault at wallace creek california three and perhaps four of these including the latest in 1857 show dextral offset of 7 5 8 m the third and fourth offsets however are just 1 4 and 5 2 m the predominance of similar offsets for the latest six events suggests that the fundamental properties of the fault system that control slip size do not vary greatly from event to event the large offsets imply that ruptures involving this site are typically more than 200 km long

slip partitioned surface breaks for the mw 7 8 2001 kokoxili earthquake china slip partitioned fault breaks have been mapped for a 70 km stretch of the 450 km surface rupture of the 14 november 2001 kokoxili earthquake simultaneous dip slip and strike slip motion on parallel faults has been proposed before but the new observations demonstrate unequivocally that it can occur in a single earthquake and allows the mechanical processes to be scrutinized observed normal fault offsets were between 0 5 and 1 m and strike slip offsets were 3 5 m the partitioned stretch of faulting has a strike that differs by 2 3 from the pure strike slip faulting to the east and west this allows a horizontal opening vector of 0 25 m to be determined for the partitioned region the distance between the two faults is greatest 2 km at the center of the partitioned portion and diminishes toward the ends the faulting is modeled to result from strains due to a buried oblique slip fault dipping at 80 to the south the depth to the top of the buried fault is shown to vary commensurately with the separation of the surface faults clear surface rupture is observed where the predicted model mechanisms are colinear and where substantial faults can develop into a kinematically stable partitioned system in a few interesting examples fragmentary oblique surface ruptures occur where the predicted mechanisms are not colinear but they are not associated with long term surface faulting the proposed mechanism for slip partitioning requires that rupture propagates upward from depth for the kokoxili surface breaks this is a consequence of coseismic dynamic rupture traveling faster at depth than near the surface leaving the surface deformation to catch up while the mechanism we propose requires slip weakening and localization to create faults or shear zones it does not require that faults with different mechanisms have different frictional behavior

rapid active thrusting along the northwestern range front of the tanghe nan shan western gansu china the western part of the tanghe nan shan range southwest of subei western gansu china is presently growing on thrust ramps splaying from the left lateral altyn tagh fault late cenozoic thrusting has folded and sliced oligocene miocence red beds into an imbricate wedge capped by warped and uplifted quaternary terraces that form a 2 to 5 km wide ledge north of the steeply faceted range front seismic scarps 1 5 to 4 5 m high cut young fans along the outer thrusts carbon 14 dating of organic remains collected on strath terraces constrains the chronology of deposition and incision by the streams most of the fans and terraces in the southern part of the subei basin appear to have been emplaced after the last glacial maximum particularly during the early holocene optimum 9 5 ka measurements of the shapes of the warped terraces constrain minimum and maximum throws on the outer thrusts the minimum vertical throw of 34 2 m of a surface dated at 8411 530 years b p at one site provides a minimum vertical uplift rate of 4 1 0 5 mm yr the maximum possible uplift 115 15 m of the oldest terrace surface whose probable age is 15 to 18 ka places an upper bound on the uplift rate of 7 2 mm yr the thrust geometry at depth and the cumulative shortening 10 20 km deduced from balancing sections logged across the imbricate thrust wedge are consistent with a shortening rate of about 5 mm yr and an onset of thrusting at about 4 2 ma such a shortening rate implies a significant northward decrease in slip rate along the altyn tagh fault the recent growth of the western qilian mountain ranges thus appears to be intimately coupled with sinistral motion on the altyn tagh fault and the extrusion of tibet

space imaging geodesy reveals near circular coseismic block rotation during the 2016 mw 7 8 kaikōura earthquake new zealand

12 000 year long record of 10 to 13 paleoearthquakes on the yammouneh fault levant fault system lebanon we present results of the first paleoseismic study of the yammouneh fault the main on land segment of the levant fault system within the lebanese restraining bend a trench was excavated in the yammouneh paleolake where the fault cuts through finely laminated sequences of marls and clays first order variations throughout this outstanding stratigraphic record appear to reflect climate change at centennial and millennial scales the lake beds are offset and deformed in a 2 m wide zone coinciding with the mapped fault trace ten to thirteen events are identified extending back more than 12 kyr reliable age bounds on seven of these events constrain the mean seismic return time to 1127 135 yr between 12 ka and 6 4 ka implying that this fault slips in infrequent but large m 7 5 earthquakes our results also provide conclusive evidence that the latest event at this site was the great a d 1202 historical earthquake and suggest that the yammouneh fault might have been the source of a less well known event circa a d 350 these findings combined with previous paleoseismic data from the zebadani valley imply that the parallel faults bounding the beqaa release strain in events with comparable recurrence intervals but significantly different magnitudes our results contribute to document the clustering of large events on the levant fault into centennial episodes such as that during the eleventh through twelfth centuries separated by millennial periods of quiescence and raise the possibility of a m 7 event occurring on the yammouneh fault in the coming century such a scenario should be taken into account in regional seismic hazard assessments and planned for accordingly

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

displacement and geometrical characteristics of earthquake surface ruptures issues and implications for seismic hazard analysis and the process of earthquake rupture there now exist about three dozen historical earthquakes for which in vestigators have constructed maps of earthquake rupture traces accompanied by de scriptions of the coseismic slip observed along the fault strike the maps and slip distributions are compiled here to place observational bounds on aspects of seismic hazard analysis and fault mechanics analysis leads to an initial statistical basis to predict the end points of rupture and the amount of surface slip expected at sites along the strike during earthquakes on mapped faults the observations also give support to the ideas that there exists a process zone or volume of about 3 4 km in dimension at the fronts of large laterally propagating earthquake ruptures within which stress changes may be sufficient to trigger slip on adjacent faults and that the ultimate length of earthquake ruptures is controlled primarily by the geometrical complexity of fault traces and variations in accumulated stress levels along faults that arise due to the location of past earthquakes to this may be added the observation that the form of earthquake surface slip distributions is better described by asymmetric rather than symmetric curve forms and that earthquake epicenters do not appear to correlate in any systematic manner to regions of maximum surface slip observed along strike online material maps of surface ruptures digitized values and curve fits to surface slip distributions and notes and references for tables 1 and 2

the repetition of large earthquake ruptures abstract this survey of well documented repeated fault rupture confirms that some faults have exhibited a characteristic behavior during repeated large earthquakes that is the magnitude distribution and style of slip on the fault has repeated during two or more consecutive events in two cases faults exhibit slip functions that vary little from earthquake to earthquake in one other well documented case however fault lengths contrast markedly for two consecutive ruptures but the amount of offset at individual sites was similar adjacent individual patches 10 km or more in length failed singly during one event and in tandem during the other more complex cases of repetition may also represent the failure of several distinct patches the faults of the 1992 landers earthquake provide an instructive example of such complexity together these examples suggest that large earthquakes commonly result from the failure of one or more patches each characterized by a slip function that is roughly invariant through consecutive earthquake cycles the persistence of these slip patches through two or more large earthquakes indicates that some quasi invariant physical property controls the pattern and magnitude of slip these data seem incompatible with theoretical models that produce slip distributions that are highly variable in consecutive large events