horizontal surface velocity and strain patterns near thrust and normal faults during the earthquake cycle the importance of viscoelastic relaxation in the lower crust and implications for interpreting geodetic data in recent years more and more space geodetic data on the surface deformation associated with earthquakes on intracontinental normal and thrust faults have become available however numerical models investigating the coseismic and postseismic deformation near such faults in a general way i e not focused on a particular earthquake are still sparse here we use three dimensional finite element models that account for gravity far field regional extension shortening and postseismic relaxation in a viscoelastic lower crust to quantify the surface deformation caused by an mw 7 earthquake on a dip slip fault the coseismic deformation is characterized by horizontal shortening in the footwall of the normal fault and extension in the hanging wall of the thrust fault consistent with elastic dislocation models geological field observations and gps data from earthquakes in italy and taiwan during the postseismic phase domains of extensional and contractional strain exist next to each other near both fault types the spatiotemporal evolution of these domains as well as the postseismic velocities and strain rates strongly depend on the viscosity of the lower crust for viscosities of 1018 1020 pa s the signal from postseismic relaxation is detectible for 20 50 years after the earthquake if gps data containing a postseismic relaxation signal are used to derive regional rates the stations may show rates that are too high or too low or even an apparently wrong tectonic regime by quantifying the postseismic deformation through space and time our models help to interpret gps data and to identify the most suitable locations for gps stations

surface rupture of the 2005 kashmir pakistan earthquake and its active tectonic implications to provide a detailed record of a relatively rare thrust surface rupture and examine its active tectonic implications we have conducted field mapping of the surface rupture associated with the 2005 m w 7 6 kashmir earthquake despite the difficulty arising from massive earthquake induced landslides along the surface rupture we found that typical pressure ridges and warps extend northwestward for a distance of 70 km with a northeast side up vertical separation of up to 7 m neither the main frontal thrust nor the main boundary thrust is responsible for the earthquake but three active faults or fault segments within the sub himalaya collectively called the balakot bagh fault compose the causative fault although the fault exhibits substantial geomorphic expression of repeated similar surface ruptures only a part of it had been mapped as active before the earthquake the location of the hypocenter suggests that the rupture was initiated at a deep portion of the northern central segment boundary and propagated bilaterally to eventually break all three segments our obtained surface rupture traces and the along strike slip distribution are both in good agreement with results of prompt analyses of satellite images indicating that space geodesy can greatly aid in time consuming field mapping of surface ruptures assuming that the extensive fill terrace in the meizoseismal area was abandoned during 10 30 ka we tentatively estimate the earthquake recurrence interval and shortening rate on the balakot bagh fault to be 1000 3300 yr and 1 4 4 1 mm yr respectively these estimates indicate that the balakot bagh fault is not a main player of himalayan contraction accommodation graphic 1 selected field photographs and arcgis files of the mapped surface rupture traces and measured vertical separations are available in the electronic supplement to this article 1 embed inline graphic 1 gif

subsurface structure physical properties fault zone characteristics and stress state in scientific drill holes of taiwan chelungpu fault drilling project continuous cores and a suite of geophysical measurements were collected in two scientific drill holes to under stand physical mechanisms involved in large displacements during the 1999 chi chi earthquake physical properties obtained from wire line logs including p and s wave sonic velocity gamma ray electrical resistivity density and temperature are primarily dependent on parameters such as lithology depth and fault zones the average dip of bedding identified from cores and fmi or fms logs is about 30 degrees towards se nevertheless local azimuthal variations and increasing or decreasing bedding dips appear across fault zones a prominent increase of structural dip to 60 80 below 1856 m could be due to deformation associated with propagation of the sanyi fault a total of twelve fault zones identified in hole a are located in the plio pleistocene cholan formation pliocene chinshui shale and miocene kueichulin formation the shallowest fault zone occurs at 1111 m depth fza1111 it is a 1 m gouge zone including 12 cm of thick indurate black material we interpreted this zone as the slip zone during the chi chi earthquake fza1111 was characterized by 1 beddingparallel thrust fault with 30 dip 2 the lowest resistivity 3 low density vp and vs 4 high vp vs ratio and poisson s ratio 5 low energy and velocity anisotropy and low permeability within the homogeneous gouge zone 6 increasing gas co2 and ch4 emissions and 7 richness in smectite within the primary slip zone in situ stresses at the drill site were inferred from leak off tests borehole breakouts and drilling induced tensile fractures from borehole fms fmi logs and shear seismic wave anisotropy from dsi logs the dominant fast shear wave polarization direction is in good agreement with regional maximum horizontal stress axis particularly within the strongly anisotropic kueichulin formation a drastic change in orientation of fast shear polarization across the sanyi thrust fault at 1712 m depth reflects the change of stratigraphy physical properties and structural geometry

the tr method the use of slip preference to separate heterogeneous fault slip data in compressional stress regimes the surface rupture of the 1999 chi chi taiwan earthquake as a case study abstract synthetic contractional fault slip data have been considered in order to examine the validity of widely applied criteria such as the slip preference slip tendency kinematic p and t axes transport orientation and strain compatibility in different andersonian compressional stress regimes radial compression rc radial pure compression rc pc pure compression pc pure compression transpression pc trp and transpression trp are examined with the aid of the win tensor stress inversion software furthermore the validity of the recently proposed graphical tr method which uses the concept of slip preference for the separation of heterogeneous fault slip data is also examined for compressional stress regimes in these regimes only contractional faults can be activated and their slip preferences imply the distinction between real i e rc rc pc and pc and hybrid i e pc trp and trp stress regimes for slip tendency values larger than 0 6 the activated faults dip at angles from 10 to 50 but in the hybrid regimes faults can dip with even higher angles the application of the tr method is here refined by introducing two controlling parameters the coefficient of determination r2 of the final tensor ratio line ftrl and the normal or inverse distribution of the faults plotted within the final tensor ratio belt ftrb the application of the tr method on fault slip data of the 1999 chi chi earthquake taiwan allowed the meaningful separation of complex heterogeneous contractional fault slip data into homogeneous groups in turn this allowed the identification of different compressional stress regimes and the determination of local stress perturbations of the regional or far stress field generated by the 1999 chi chi earthquake this includes clear examples of stress permutation and stress partitioning caused by pre existing fault structures such as the n s trending chelungpu thrust and the ne sw trending shihkang shangchi fault zone

extensional polarity change in continental rifts inferences from 3 d numerical modeling and observations abstract extensional basins often show along strike variability in terms of fault geometries basement structures subsidence and thermal evolution this is particularly pronounced when extension reactivates preexisting suture zones with opposing dip directions that is opposite polarities which creates wide strike slip transfer zones we have studied this extensional variability by means of thermomechanical lithospheric scale 3 d numerical modeling we conducted a series of experiments to model the extension of a thick lithosphere simulating a young orogenic area containing segmented suture zones inherited from former opposing subduction polarities implemented as rheologically weak inclined layers with opposite dips numerical experiments demonstrate that the initial subduction sutures are reactivated by two long lived lithospheric scale detachment faults which remain active until the onset of oceanic spreading the opposite polarity of these faults causes their migration toward each other by asymmetric mantle lithosphere extension and thermal accretion crustal kinematics shows the formation of extensional detachment faults and high offset listric normal faults these structures undergo gradual tilting during their footwall exhumation while the rheological weak suture layers are redistributed beneath the crust the results demonstrate an active interaction along the strike of the system between the two opposite dipping weak zones where fault segments mechanically interact during extension the maximum horizontal fault offset switches the apparent sense of shear in the separating strike slip transfer zone this kinematics explain the rapid change in the sense of shear in major strike slip transfer zones or transform faults such as observed during the extension of the pannonian back arc basin

truncated higher order sequences as responses to compressive intraplate tectonic events superimposed on eustatic sea level rise abstract high resolution sequence stratigraphic analysis of the lignite bearing miocene siliciclastic sequence of the salotarjan lignite formation slf has been performed by lithostratigraphic dissection of more than 1350 boreholes and by detailed analysis of well logs from more than 150 boreholes biostratigraphic data indicate that the slf represents a single 3rd order eustatic sequence namely the bur 4 of vakarcs et al vakarcs g hardenbol j abreu v s vail p r varnai p tari g 1998 oligocene middle miocene depositional sequences of the central paratethys and their correlation with regional stages sepm special publication vol 60 209 231 as for facies conditions facies models for sandy shorefaces and or wave dominated deltas can be applied twenty six parasequences have been identified and mapped in the adjacent sub basins from well log correlations the sharp based sand bodies of ps 10 and 17 were interpreted as the falling stage systems tract fsst of higher order sequences the subsequent transgressive systems tracts tst are represented by retrograding sets of 2 3 parasequences ps 11 13 18 19 based on the regional unconformity at the base and the regionally extended sharp based sand bodies three sequence boundaries sb were determined that dissect the 3rd order sequence into three higher order sequences one of the special features of the sequence is that the fssts interrupt the rapid relative sea level rises ps 9 and 16 and lie directly on the silty material of nearshore environments leading to the lack of the higher order highstand system tracts hst truncated transgressive semi cycles another characteristic is the striking basinward fore stepping of the sedimentary depocentres and that of the facies belts of the lignite seams the rapid relative sea level falls implied by the two fssts are unexpected in the context of an overall eustatic rise thus the possibility of tectonic origin of shallowing was investigated this verification was based primarily on the observations that 1 the basin was united when parasequences 1 to 13 were developed whereas 2 by the end of the sequence development the palaeozoic basement protruded to the surface dividing the basin reflecting intense tectonic events simultaneous with sequence development the fssts with the sbs above and the formation of higher order sequences can thus be regarded as sedimentary responses to syn sedimentary tectonic elevation and tilting of the basement this elevation was induced by tectonic compression and associated imbrication along a regional reverse fault that was known as the darno line the imbrication could have controlled not only the repeated relative sea level falls but also the striking fore stepping of the sedimentary depocentres and facies belts of the associated lignite seams tectonic tilting influenced not only the fssts but the subsequent early tsts as well thus lignite seams associated with the tectonically counteracted tsts are characterized by multiple seams with several accessory seams va iiia b and ia while those associated with tectonically quiescent periods are aerially extensive and solitary comparison with other coal bearing formations enhanced the importance of the fsst in the interpretation of stratigraphic truncations coal seam geometry conditions facies shiftings and stratal geometry enabling a more accurate description of syn sedimentary tectonic events

structure of the 1999 chi chi earthquake rupture and interaction of thrust faults in the active fold belt of western taiwan abstract we summarize the structural characteristics of the surface ruptures of the 1999 mw 7 6 chi chi earthquake in western taiwan and discuss the geological interaction of the chelungpu fault with adjacent faults based on geological investigations seismological analyses and gps measurements of surface co seismic displacements we describe the regional 3 d fault plane and slip distribution of the chi chi earthquake and compare these to the geological features of the chelungpu fault we find that one key feature of the chelungpu fault is the stratigraphy controlled slip surface at the level of the uppermost few kilometers the chelungpu fault slip plane generally follows the bedding plane of the pliocene chinshui shale the second key feature of the chelungpu fault is the difference in structurally geometric configuration between its northern and southern segments the northern fengyuan segment shows a bedding parallel thrust fault within east dipping strata in both footwall and hanging wall in contrast the southern tsaotun segment exhibits east dipping strata are overthrust onto flat lying recent alluvial deposits these two features not only explain a hinterland imbricate thrusting on the hanging wall of the fengyuan segment but also explain the change in strike of the chi chi surface ruptures at the northern end the southern end of the 1999 chi chi rupture is interpreted to be linked to a series of nw trending strike slip faults in particular we propose that the luliao strike slip fault served as the lateral ramp of the chelungpu fault and the gukeng strike slip fault acted as a barrier to end the southern propagation of the 1999 rupture geomorphic features and paleoseismological data indicate that the range front chelungpu fault has generated large earthquakes during the last several thousand years alternatively in the miaoli area to the north and the chiayi area to south historical earthquakes as well as active geomorphic features are not restricted on the range front thrust faults instead more complicated structures including tightly spaced folds duplex structures and strike slip faults are involved in seismogenic processes a more detailed investigation of regional structural characteristics is needed for mitigation against the seismic hazards in the 300 km long active fold belt in western taiwan where several damaging large earthquakes have been documented during the last century

structural geology of a classic thrust belt earthquake the 1999 chi chi earthquake taiwan mw 7 6 abstract we document the structural context of the 1999 chi chi earthquake m w 7 6 in western taiwan which is one of the best instrumented thrust belt earthquakes the main surface break and large slip 3 10 m is on two segments of the shallow otherwise aseismic bedding parallel chelungpu sanyi thrust system which shows nearly classic ramp flat geometry with shallow detachments 1 6 km in the pliocene chinshui shale and mio pliocene kueichulin tungkeng formations however rupture is complex involving at least six faults including a previously unknown deeper thrust 8 10 km on which the rupture began we compare the coseismic displacements with a new 3d map of the chelungpu sanyi system the displacements are spatially and temporally heterogeneous and well correlated with discrete geometric segments of the 3d shape of the fault system geodetic displacement vectors are statistically parallel to the nearest adjacent fault segment and are parallel to large scale oblique fault corrugations the displacement magnitudes are heterogeneous at several scales which requires in the long term other non chi chi events or significant aseismic deformation the chelungpu thrust has a total displacement of 14 km but the area of largest chi chi slip 10 m is on a newly propagated north chelungpu chinshui detachment 0 3 km total slip which shows abnormally smooth rupture dynamics

interaction of basin margin faults and tidal currents on nearshore sedimentary architecture and composition a case study from the early miocene of northern hungary abstract the darno conglomerate and the petervasara sandstone with conglomeratic intercalations both cropping out in northern hungary were formed along the eastern margin of the shallow early miocene sea within the carpathian arc ophiolite derived clastic components in both formations indicate a close genetic relationship with each other and with the activity of the basin margin darno fault which seems to correspond with the coeval shoreline the darno conglomerate was part of a small fault controlled fan delta supplying coarse clastics into the sea where the petervasara sandstone deposited the conglomerates occur as small lobes interbedded within a field of tidally driven sand waves the coarse grained clastics which were admixed to the main material of the sandstone have been derived from triassic jurassic ophiolite related series meliata nappes east of the darno fault the composition of the lobes indicates that they were formed as small spit like platforms attached to the fan deltas of the darno conglomerate as base level rose spits became drowned and their sediment was washed into the basin and reworked by the strong northward directed tidal currents into elongated lobes mimicking sand waves a reduction in the amount of the less resistant pebble components of ophiolite related origin and a relative enrichment of the resistant components towards the west indicate that pebbles had partly been transported in the offshore direction the increasing rate of accumulation of ophiolite derived heavy minerals and pebbles along the northern part of the coast indirectly suggests a contemporaneous left lateral displacement along the basin margin darno fault

simulation of foreland basin stratigraphy using a diffusion model of mountain belt uplift and erosion an example from the central alps switzerland foreland basin stratigraphy can be considered as the result of three interacting processes thrust deformation which builds the tectonic load sedimentary and erosional processes which redistribute that load and the flexural response of the lithosphere the resultant stratigraphy of foreland basins is commonly composed of a small number of shallowing and coarsening upward cycles bounded by regional unconformities to understand the development of these unconformities we present a simple model of these three processes coupling an evolving thrust wedge on a linear elastic plate with erosion and sedimentation defined by the diffusion equation applied to topography our model demonstrates the development of regional unconformities without recourse to either eustasy or complex viscoelastic models for the continental lithosphere the model describes the thrust wedge foreland basin system in terms of four parameters 1 the effective elastic thickness of the foreland plate te 2 the sediment transport coefficient k 3 the thrust wedge advance rate 4 the surface slope of the thrust wedge the model is applied to the oligocene miocene north alpine foreland basin nafb of eastern switzerland the stratigraphy of the nafb can be simplified into two large scale shallowing upward cycles separated by an unconformity at the base of the burdigalian 22 ma geological information is taken from the nafb to estimate suitable values for the parameters listed above assuming a linear elastic lithospheric rheology the te value is estimated at 10 5 km from decompacted sediment columns data to constrain the sequential development of the thrust wedge come from structural geology the early stages 40 24 ma of compression involved a relatively low angle thrust wedge with an advance rate of approximately 2 4 mm yr at about 24 ma the wedge advance slowed down and thickened by underplating crystalline basement of the foreland plate the value for the transport coefficient has been estimated from previous studies prior to attempting to simulate the broad scale geometry of the nafb the role of each parameter was assessed individually the values for te and k are held constant throughout the simulation of the nafb at 7 5 km and 500 m yr respectively the geometry of the base burdigalian unconformity is reproduced by variations in the parameters describing the thrust wedge the surface slope angle of the wedge is increased from 2 5 to 4 over 0 2 m y and the rate of thrust advance is decreased from 2 mm yr to 0 2 mm yr during the thickening event between 24 and 23 8 ma the rejuvenation of the internal parts of the thrust load causes backtilting of the foreland basin sediments and after a time lag erosion of the distal stratigraphy over the forebulge so simulating the base burdigalian unconformity

kinematic and dynamic fault slip analyses implications from the surface rupture of the 1999 chi chi taiwan earthquake the 1999 chi chi earthquake created a 100 km long surface rupture on the chelungpu thrust fault in taiwan due to convergence between the phillipine sea and eurasian plates fault slip measurements were made by several researchers from the entire length of the rupture directly following the earthquake and can thus be attributed to a single tectonic event conventional fault slip analyses are applied to these data and the results are compared with independent seismological and kinematic observations unlike many fault slip analyses complications due to multiple deformations can be categorically excluded and the results can be evaluated from the seismological and plate movement data kinematic analyses of fault slip data that are weighted by displacement show sub horizontal nw se shortening that is parallel to the plate convergence vector a single fault plane solution satisfies almost all the data right dihedra and trihedra solutions also satisfy almost all the surface rupture measurements and give 1 in a nw se orientation that is similar to the results of stress inversion and to inversion from earthquakes in the chi chi earthquake sequence despite criticisms of fault slip analysis methods these results show that fault slip analyses from data collected along major faults which have not witnessed multiple deformation events can be valid homogeneous strain and stress states exist in the sense that kinematic and dynamic solutions can be found that fit essentially all the data and these solutions have tectonic significance

determination of horizontal shortening and amount of reverse faulting from trenching across the surface rupture of the 2008 mw 7 9 wenchuan earthquake china abstract the 2008 wenchuan earthquake m w 7 9 ruptured two large thrust faults within the longmenshan fault zone along the eastern margin of the tibetan plateau the beichuan yingxiu fault and the guanxian jiangyou fault previously coseismic displacements including vertical and horizontal slip along the surface rupture have been investigated in detail along with far field horizontal shortening estimated using gps measurements however the distribution of near field horizontal shortening across the surface rupture is relatively ambiguous because there are few markers in the earthquake zone and very few appropriate landforms for surveying palinspastic restoration of paleoseismic trench logs as an alternative approach may compensate for these deficiencies and reflect true deformation types and shortening across the surface rupture we present several methods for estimating shortening based on the genesis of earthquake scarps the results demonstrate that the shortening ranges from 2 5 m to 0 6 m for localities along the guanxian jiangyou fault with the highest values at the southwestern end along the beichuan yingxiu fault near field shortening ranges from 1 3 m to 3 4 m with two maxima toward the ne and sw ends of the fault near the towns of shenxigou and leigu these locations correlate with the two most heavily damaged regions horizontal shortening on the guanxian jiangyou fault is generally less than that across the beichuan yingxiu fault based on the distribution of near field horizontal shortening from trenching across surface rupturing the maximum near field horizontal shortening across the surface rupture for the wenchuan earthquake is 5 3 m

revealing coseismic displacement and displacement partitioning at the northern end of the 1999 chi chi earthquake central taiwan using digital cadastral data abstract the 1999 chi chi taiwan earthquake m w 7 6 was the largest earthquake to strike taiwan in the twentieth century its surface rupture extends more than 100 km in a north south trend however the northern end of this surface deformation abruptly terminates at an area between the tachia river and the taan river where a broad pop up structure with east to northeast strike quite different from the north south striking main thrust is found this pop up structure is composed of several regions of parallel thrusts and back thrusts and total shortening reaches about 9 m in order to reveal the displacement field in the pop up structure and slip vectors of branch faults we use a digital cadastral system with about 17 000 control points to calculate coseismic displacement around the shihkang area the digital cadastral system was originally conceived to survey land and building boundaries the cadastral system affords high density control points that reach about 2800 points km 2 and the accuracy is to within 11 cm outside of the pop up structure the horizontal displacements vectors are 8 9 m in about 330 340 changing as they pass through the surface rupture the azimuth of horizontal displacement shows large variation with the azimuth from 360 to 315 and displacement amounts from about 4 8 m inside the pop up structure in addition according to these cadastral data we found surface ruptures that had not been observed in previous studies that could be of importance to future disaster assessment

the chi chi earthquake sequence active out of sequence thrust faulting in taiwan we combined precise focal depths and fault plane solutions of more than 40 events from the 20 september 1999 chi chi earthquake sequence with a synthesis of subsurface geology to show that the dominant structure for generating earthquakes in central taiwan is a moderately dipping 20 to 30 thrust fault away from the deformation front a second subparallel seismic zone lies about 15 kilometers below the main thrust these seismic zones differ from previous models indicating that both the basal decollement and relic normal faults are aseismic

basin dimensions and morphology as controls on amplification of tidal motions the early miocene north hungarian bay following the late aquitanian sea level fall tide influenced deposition started in the north hungarian bay an embayment in the paratethys open to the north east the relatively narrow funnel shape of the bay supported amplification of tidal movements resulting in the generation of strong tidal currents the length and the depth of the north hungarian bay and the connecting seaway through east slovakia fell into the tidal amplification window and thus fulfilled the conditions needed for resonant amplification of semidiurnal m2 tides tide influenced deposits were formed at both sides of the north hungarian bay they reflect dominant currents in opposite directions and of different strengths at either side of the basin this difference was the result of bottom tide interactions cyclonic anticlockwise residual currents were induced above the asymmetrical central depression in the bay and were superimposed upon the tidal currents producing an anticlockwise time and velocity asymmetrical current system the north hungarian bay and other examples show that amplification of tidal motions and formation of tide influenced deposits may occur if basin dimensions pass through the tidal amplification window this window represents ideal conditions for resonant or amphidromic amplification of tidal currents it determines an ideal length depth or width depth ratio relative to the wavelength of the astronomical tides thus signs of strong tidal influence in fossil basin fills can be used to reconstruct the dimensions length depth and width of such basins

u pb and 40ar 39ar dating of the miocene fossil track site at ipolytarnoc hungary and its implications abstract abundant early miocene mammal and bird tracks and a rich plant assemblage is preserved by the emplacement of an ignimbrite sheet of the gyulakeszi rhyolite tuff formation grtf near ipolytarnoc in northern hungary the tuff that overlies the track bearing sandstone yielded a single crystal zircon u pb total isochron age of 17 42 0 04 ma and a single crystal laser fusion plagioclase 40 ar 39 ar age of 17 02 0 14 ma uncertainties are quoted at the 2 level an additional 40 ar 39 ar age of 16 99 0 16 ma was obtained from the equivalent rhyolite tuff near nemti where the underlying terrestrial clay yielded early proboscidean remains assigned to the mn4 mammal zone the new high precision dates allow revision of the numeric age and correlation of the ipolytarnoc fossil site and the grtf previously based on an average k ar age of 19 6 1 4 ma the difference of 0 40 0 15 ma between the u pb and 40 ar 39 ar ages support the growing evidence for a systematic bias between the two isotopic systems due to the inaccurately known 40 k decay constant but likely also includes an undetermined pre eruptive residence time of zircon published biostratigraphic data from under and overlying marine strata establish correlation with the nn3 nannoplankton zone and together with the new radioisotopic ages suggest assignment of the fossils and the tuff to the ottnangian regional stage of the central paratethys a global correlation lends support to the recently suggested astronomical calibration of the early miocene time scale that revised the previous scales towards younger ages the 40 ar 39 ar age from nemti provides a reliable correlation of the mn4 mammal zone in central europe with the numeric time scale and places a minimum constraint on the age of the regional proboscidean datum the migration event of proboscideans from africa to europe through the emerging gomphotherium landbridge contrary to suggestions for a significantly earlier european proboscidean datum it appears that the originally suggested age of c 17 5 ma is realistic but it is significantly younger than the south asian proboscidean datum

petrology of the plio quaternary volcanism of the south central and meridional andes plio quaternary volcanoes lay upon a continental crust which is thick and of precambrian paleozoic age in the south central andes sca 18 28 s whereas it is relatively thin and of mesozoic cenozoic age in the meridional andes ma 32 42 s eleven calc alkaline volcanic massifs or groups of small volcanoes and two shoshonitic volcanoes have been studied in the sca eleven calc alkaline volcanic massifs have been studied in the ma one alkaline volcano has been approached in argentinian patagonia calc alkaline lavas are mostly andesites and dacites in the sca and high al basalts and basic andesites in the ma shoshonitic lavas are absarokites shoshonites and banakites no cognate xenoliths were found in the lavas the texture of the lavas is microlitic with abundant calc alkaline lavas or rare shoshonitic lavas phenocrysts distribution of phenocrysts opposes calc alkaline lavas of the sca with hornblende and biotite to those of the ma with olivine in calc alkaline lavas plagioclase is the most abundant mineral phase from high al basalts an90 to rhyolites an20 olivine is fo78 65 phenocrysts in basic lavas clinopyroxene ca mg rich augite and orthopyroxene bronzite show little compositional variation with lava differentiation amphibole is pargasitic or edenetic hornblende crystal clots which result from resorption of hornblende are found biotite is ti rich phenocrysts of quartz are found in rhyolites and rimmed by pyroxenes in basic lavas of the sca microlites of magnetite are ubiquitous and phenocrysts occur only in the sca in the sca geothermometers and geobarometers give the following results equilibration temperatures which decrease from 1000 c in andesites to 900 c in dacites h2o pressures vary between 1 and 4 kbar and oxygen fugacities are higher than the ni nio buffer basic lavas may have equilibrated at 50 km depth in shoshonitic lavas plagioclase and k feldspar are present olivine is fo85 phenocrysts and fo65 microlites clinopyroxene is cr rich orthopyroxene is bronzite in shoshonites microlites and banakites microlites and phenocrysts hornblende is pargasitic biotite is t rich in banakites conditions of differentiation of the lavas are high temperatures 850 1050 c water pressures inferior to 2 kbar oxygen fugacities above the ni nio buffer and total pressures which correspond to depths of 80 120 km major and trace element distributions emphasize differences between calc alkaline associations of the sca and ma and between calc alkaline and shoshonitic associations in shoshonitic lavas decreases in mgo and ni cao and cr al2o3 and sr correspond to respective olivine clinopyroxene and plagioclase fractionations incompatible elements circum pacific characteristics high al2o3 constant na2o3 increasing k2o with differentiation andean characteristics low cao and peculiar characteristics ma lavas have lower mgo olivine fractionation in the sca lavas have lower tio2 and feo fractionations of magnetite pyroxenes and hornblende the origin of the andean magmatism is not consistent with single stage models anatexis of continental crust crystal fractionation of basaltic magma under amphibolite or eclogite facies partial melting of peridotitic upper mantle material a three stage model is proposed the first stage consists of partial melting of upper mantle material loss in fluids of the subducted oceanic crust induces the melting bubbles of primary magma are generated the second stage consists of selective crustal contamination during the stay of the magma at the base of the continental crust the third stage consists of low pressure crystal fractionation which governs the differentiation of the lava series the present model considers transversal and longitudinal zonation of the andes high degrees of melting low rate of contamination and reduced crystal fractionation characterize the ma whereas low degrees of melting high rate of contamination and considerable crystal fractionation characterize the sca garnet is involved in the genesis of shoshonitic lavas

review of neogene and quaternary volcanism of the carpathian pannonian region abstract development of the pannonian basins as well as thrusting and folding of the carpathians was accompanied by widespread volcanic activity this volcanism can be divided into three main genetic types 1 1 early miocene mainly acidic volcanism tuffs and ignimbrites the recent spatial separation of these volcanics may be due to large right lateral displacement along the mid hungarian shear zone during the early miocene 2 2 middle miocene pliocene calc alkaline mainly intermediate stratovolcanic complexes in the inner western carpathians and in the east carpathians related to a subducted oceanic slab their geochemical compositions show a transitional character between active continental margin and island arc type magmatic rocks the thickness of the crust increased with time and from west to east beneath this volcanic arc 3 3 pliocene pleistocene alkali basaltic volcanism was related to an upwelling then cooling asthenospheric dome this is thought to have initiated the thermal regime from which these melts ascended the compositional difference in space and in time might reflect the existence of local individual small sized diapiric bodies as well as several processes e g fractional crystallization mixing which modified the original magma the eruption of these basaltic melts was temporally associated with the final phase of development of the pannonian basin this volcanism was associated with recent uplifts and tectonic rejuvenation of the area

velocity field of gps stations in the taiwan area abstract the 131 stations of the taiwan gps network were surveyed 4 6 times from 1990 to 1995 with dual frequency geodetic receivers the standard deviation of an observed baseline length with its linear trend removed is in the range of 6 10 mm for a 3 120 km long baseline the average rates of length change for all baselines of the network and those from nine continuously monitoring permanent stations are used in a least squares adjustment to estimate the velocities of the gps stations relative to paisha penghu situated at the chinese continental margin to the south of fengping in the northern coastal range the velocity vectors of stations in lanhsu lutao and the coastal range trend in the directions of 306 322 with rates of 56 82 mm yr in contrast there is a dramatic decrease in the rates to the north of fengping this may be caused by the motion along the ne sw trending thrusts which obliquely cut the northern coastal range a discontinuity of about 30 mm yr in the rates along with a remarkable change in the directions of station velocity is observed across the longitudinal valley then the moving directions gradually shift to the west for the stations in the western foothills in the kaohsiung pingtung coastal area the station velocities are even directed toward the southwest to the north of the peikang high the velocity vectors of the stations change direction from the west gradually to the north and finally to the east and southeast significant nw se extensional deformation is found in the ilan plain and northern taiwan in general the pattern of the velocity field for gps stations in the taiwan area is quite consistent with the directions of present day tectonic stress

tertiary evolution of the intra carpathian area a model abstract the outer carpathian flysch nappes encircle an intra carpathian domain which can be divided into two megatectonic units north pannonian and tisza mostly on the basis of contrasting mesozoic and palaeogene facies development we see two major kinematic problems to be solved 1 1 the present distribution of the mesozoic and palaeogene facies is mosaic like and some belts form exotic bodies within realms of austroalpine affinity 2 2 late eocene palinspastic reconstruction of the outer carpathian flysch nappes suggest that the entire intra carpathian area must have been located several hundreds of kilometres to the south and to the west of its present position neogene extension can account for shortening in the external carpathian nappes but is unable to explain mesozoic facies anomalies and offsets of palaeogene formations we suggest that evolution of the intra carpathian area involved first late palaeogene early miocene juxtaposition of the north pannonian and tisza megatectonic units accompanied by the closure of the external carpathian flysch troughs thereafter extension of this amalgamated unit occurred which was compensated by thrusting of flysch nappes onto the european foreland and formation of molasse foredeeps eastward escape of the north pannonian unit from the alpine collisional belt involved left lateral shear along the pieniny klippen belt and right lateral shear along the mid hungarian zone parts of the late palaeogene basin and an early miocene volcanic edifice were dissected offset and elongated by several 100 kms the driving mechanism of the eastward escape of the intra carpathian area can be related to the collision of apulia and europe and the subduction of the external carpathian crust under the pannonian units the escape ceased gradually in the early miocene when oblique collision between the north pannonian unit and european continent occurred neogene extension of the pannonian region was an areal deformation the extension at locally variable rate resulted in the break up of the heterogenous floor of the neogene basin the driving mechanism of basin extension and contemporaneous compressional deformation of the external carpathians is thought to be related to ongoing subduction involving the marginal part of the attenuated european continental crust tectonic activity in the carpathians and basin subsidence and volcanism shifted in time and in unison from the west toward the east southeast

paleoseismology and tectonic geomorphology of the pallatanga fault central ecuador a major structure of the south american crust the pallatanga fault pf is a prominent nne ssw strike slip fault crossing central ecuador this structure is suspected to have hosted large earthquakes including the 1797 riobamba event which caused severe destructions to buildings and a heavy death toll more than 12 000 people as well as widespread secondary effects like landsliding liquefaction and surface cracking the scope of this study is to evaluate the seismic history of the fault through a paleoseismological approach this work also aims at improving the seismotectonic map of this part of the andes through a new mapping campaign and finally aims at improving the seismic hazard assessment we show that the pf continues to the north of the previously mapped fault portion in the western cordillera rumipamba pallatanga portion into the inter andean valley riobamba basin field evidences of faulting are numerous ranging from a clear geomorphological signature to fault plane outcrops along the western side of the riobamba basin the strike slip component seems predominant along several fault portions with a typical landscape assemblage dextral offsets of valleys fluvial terrace risers and generation of linear pressure ridges in the core of the inter andean valley the main fault portion exhibits a vertical component along the c 100 m high cumulative scarp the presence of such an active fault bounding the western suburbs of riobamba drastically increases the seismic risk for this densely inhabited and vulnerable city to the east peltetec massif cordillera real the continuation of the pallatanga fault is suspected but not definitely proved yet based on the analysis of three trenches we state that the rumipamba pallatanga section of the pf experienced 4 maybe 5 holocene to historical strong events mw 7 the coseismic behavior of the fault is deduced from the occurrence of several colluvial wedges and layers associated with the fault activity and interbedded within the organic black soil sequence according to a series of 14c datings we document that these events occurred during the last 6500 years the clear deformation of the shallowest layer 14c 1633 ad is most likely associated with the 1797 riobamba earthquake after retrodeforming one of the 3 trenches we estimate coseismic vertical throws 0 70 to 0 90 m because of bad outcrop conditions we could not determine the horizontal component of slip and we used the slip vector determined in a previous work with a tectonic geomorphology study assuming this slip vector we obtain total coseismic offsets between 3 5 and 4 5 m indicative of earthquake magnitudes around c mw 7 5 the estimated recurrence time intervals range between 1300 and 3000 years indicating an average slip rate of c 2 5 mm a for the rumipamba pallatanga section of the fault

segmentation of the western taiwan active fault zone inferred from its structural analogy to the nankai trough region southwest japan abstract a west facing active fold and thrust structure is typified by the three thrust sheets soled by the frontal changhua central chelungpu and hindward shuangtung faults in the taichung area central western taiwan the least deformed changhua sheet comprises an n s trending frontal structural high and a parallel inner basin the chelungpu and shuangtung sheets deform an n s trending syncline that originates from an older basin the n s striking structures are traversed or overlain by ene wsw trending structures such as the ene striking tuntzuchiao fault and adjoining eastward bends of the northern tips of the chelungpu and shuangtung faults such transverse structures are located in three other areas of western taiwan near hsinchu north of chiayi and north of tainan the configuration of the island parallel and transverse structures mimics structural features of the rupture units of interplate earthquakes off southwest japan which are produced by right oblique subduction of the philippine sea plate along the nankai trough this suggests that the western taiwan active fault zone can be divided into five rupture areas 60 80 km long and may be controlled by left oblique convergent tectonics at the northern extension of the manila trench

early miocene basin evolution in northern hungary tectonics and eustasy abstract it is presumed that the oligocene early miocene basin evolution in northern hungary was primarily driven by compressional tectonics producing a major second order transgressive regressive facies cycle the early miocene basin evolution is best understood in terms of molasse sedimentation in an overfilled flexural basin during this time the gradual cessation of thrusting in the adjacent west carpathian thrust fold belt resulted in its uplift and subaerial exposure significant amounts of sediment were delivered to the flexural basin filling it up to sea level during the late stage uplift of the flexural basin a shallow marine depositional environment developed as a result of isostatic rebound and signals of third order eustatic sea level changes can be revealed sedimentological studies of outcrops of the lower miocene succession proved marked changes in facies along the gently dipping distal southeastern flank of the basin a sudden inception of shallow marine coarse elastics on top of siltstones deposited in significantly deeper water may have been the result of a third order eustatic sea level fall shortly before the burdigalian at the boundary of the nn1 nn2 nannofossil zones during the resulting lowstand various tide dominated facies aggraded which were subsequently flooded by the burdigalian sea level rise the highstand is represented by upwards shallowing progradational units due to accelerating sedimentation and or tectonic uplift the typically elongated and narrow flexural basin characterized by small water depth had dimensions which were particularly suitable for the amplification of tidal motions this resulted in the deposition of tide influenced sandy sediments in contrast to examples where the evolution of a strong tidal influence is related to transgressions here such conditions developed following a drop of sea level

contrasting strike slip motions on thrust and normal faults implications for space geodetic monitoring of surface deformation recent global positioning system gps records of surface deformation caused by earthquakes on intracontinental dip slip faults revealed in unprecedented detail a significant strike slip component near the fault tips that is markedly different for thrust and normal faults in the hanging wall of the thrust fault ruptured during the a d 2003 chengkung taiwan earthquake a divergent displacement pattern was recorded in contrast a convergent slip pattern was observed in the hanging wall of the normal fault that produced the 2009 l aquila italy earthquake such convergent slip patterns are also evident in field records of cumulative fault slip from central italy which underlines the coseismic origin of cumulative displacement patterns here we use three dimensional numerical modeling to demonstrate that the observed fault parallel motions are a characteristic feature of the coseismic slip pattern on normal and thrust faults modeled slip vectors converge toward the center of normal faults whereas they diverge for thrust faults this causes contrasting fault parallel displacements at the model surface our model also predicts divergent movements in normal fault footwalls which were recorded for the first time during the l aquila earthquake during the postseismic phase viscous flow in the lower crust induces fault parallel surface displacements which have the same direction as the coseismic displacements but are distributed over a larger area that extends far beyond the fault tips therefore detecting this signal requires gps stations in the prolongation of the fault strike postseismic velocities vary over several orders of magnitude depending on the lower crustal viscosity and may reach tens of millimeters per year for low viscosities our study establishes the link between coseismic and cumulative slip patterns on normal and thrust faults and emphasizes that understanding fault parallel slip components and associated surface displacements is essential for inferring regional deformation patterns from space geodetic and fault slip data

gravity flow dominated sedimentation on the buda paleoslope hungary record of late eocene continental escape of the bakony unit the upper eocene sequence of the buda hills consists of fluvial and shallow marine conglomerates sandstones bioclastic shallow water limestone marlstone and pelagicglobigerina marl the succession illustrates rapid overall subsidence of the area from terrestrial environments to bathyal depths sedimentation occurred on slopes situated on the flanks of synsedimentary basement antiforms vertical growth of antiforms caused progressive tilting of beds layer parallel extension by boudinage and faulting and induced redeposition by mass flow antiforms are localised in the dextral budaors shear zone and in the buda imbricate stack which accommodated the dextral displacement the latter is underlain by blind reverse faults probably merging into a detachment fault at shallow depths these structures were formed by wnw ese oriented compression and nne ssw directed tension the morphological expression of the imbricate stack is the se facing buda slope the bakony unit while escaping from the alps was bordered by a northern sinistral and a southern dextral shear zone synsedimentary tectonics in the buda hills demonstrates the style of deformation inside the escaping block close to the southern border zone tectonically controlled sedimentation suggests that escape tectonics was active as early as late eocene time

paleogene retroarc flexural basin beneath the neogene pannonian basin a geodynamic model abstract the neogene middle miocene recent pannonian basin is superimposed on an earlier paleogene middle eocene early miocene basin complex as a result of back arc extension although the stratigraphy of the latter is very well known due to raw material exploration its formation and structural evolution is much less understood a transtensional origin was generally proposed for the paleogene basin of hungary assuming an origin analogous to that of the overlying neogene pannonian basin we suggest an alternative geodynamic scenario for the development of the paleogene basin complex as we think that the observations are better understood in terms of a retroarc foredeep basin model according to this a flexural basin developed south of the backthrust inner west carpathian units the thrust load resulted in a generally deep underfilled flysch basin during middle eocene early oligocene times in the late oligocene early miocene predominantly shallow marine and continental deposition occurred indicating the gradual cessation of thrusting in the adjacent thrust fold belt and the beginning of molasse sedimentation throughout the whole paleogene a shift can be observed of the bathyal dominantly siliciclastic in the axis of the foredeep and neritic partly carbonate in the foreland flank of the foredeep facies belts this migration of the middle eocene early miocene depocenters of the hpb hungarian paleogene basin to the east northeast in present day coordinates is the result of two processes 1 1 the advancement of backthrusting to the southeast 2 2 along strike shift of thrusting to the northeast while a thin skinned thrust front can be reconstructed for the late eocene buda anticline the diosjeno hurbanovo line is interpreted as the result of a major thick skinned thrusting event at the base of the np24 zone 31 ma the subsidence pattern the distinct depositional environments and the structural observations can be more easily integrated into a flexural basin model than into a wrench basin model based on the flexural basin model of this work the early tertiary western carpathians formed a compressional arc while this arc probably developed above a b subduction zone during the late eocene with a corresponding trench magura a forearc basin central carpathian or podhale and a retroarc flexural basin hungarian paleogene from the early oligocene to the early miocene it was characterized by a subduction with a corresponding peripheral foredeep dukla and silesian and a retroarc flexural basin hungarian paleogene

combination of palaeomagnetic and stress data a case study from north hungary abstract the paper presents the results of a combined palaeomagnetic and microtectonic study in north hungary it analyses the relationship between palaeomagnetically indicated rotations and stress axes at both site and regional level as a result appropriate palaeomagnetic corrections are determined for different sets of microtectonic structures the orientation of the stress axes is restored to its original position by correcting for mass rotation as it is manifested in declination deviation from the present north this process eliminates the apparent rotation of the stress field during the early miocene however our investigations show that real change in orientation of stress axes about 20 did occur during the middle miocene the reconstructed stress field is in good agreement with kinematic models which suggest eastward escape of the area as part of the north pannonian block our results may be best interpreted by attributing the palaeomagnetically indicated rotations partly to rotation of the whole area as a relatively rigid body and partly to local block rotations

surface ruptures on the transverse xiaoyudong fault a significant segment boundary breached during the 2008 wenchuan earthquake china abstract the 220 km long rupture of the 2008 mw 7 9 wenchuan earthquake breached several km scale geometric discontinuities along strike including the previously un mapped nw trending xiaoyudong fault connecting between the two major ne trending rupture planes on the beichuan and pengguan faults in this paper we present high resolution mapping of the 8 km long surface breaks and sinistral oblique thrusting coseismic slip on the xiaoyudong fault scarp height is the largest at the nw end reaching 3 5 m and decreases southward in steps to less than 0 2 m with an average slip gradient of 6 10 3 at a few tens of meters length scale but up to 50 10 3 locally left lateral offsets co vary with the vertical component the largest sinistral slip vector we observed is 2 2 m geological and geophysical evidence suggests that the xiaoyudong fault is likely a 30 sw dipping lateral ramp that soles into the pengguan fault and at its northwestern end intersects with the beichuan fault where the latter has a step in the fault plane kinematically the xiaoyudong fault functions as a tear and conjugate fault and coincides with significant coseismic slip rake rotations on both the beichuan and pengguan faults similar correlation of fault bends with sharp changes in faulting style occurs at other steps along the wenchuan rupture the xiaoyudong fault may have played a positive role in linking coseismic slip partitioning between parallel reverse fault planes facilitating the growth of a longer and more destructive rupture this highlights the role of tear faults in bridging ruptures between segments such that reverse type ruptures can breach steps wider than anticipated from strike slip fault examples transfer faults are common and perhaps poorly documented features in reverse fault systems and their roles in ruptures may increase the maximum potential earthquake magnitude for fold and thrust belts

palaeogeographic significance of tidal deposits an example from an early miocene paratethys embayment northern hungary abstract tide influenced deposits can be used in palaeogeographic reconstructions because they are good indicators of open marine connections an example is presented from the eggenburgian late aquitanian early burdigalian of the north hungarian bay this bay was part of an inland sea the paratethys tide influenced deposits prove that tidal motions in the north hungarian bay were locally amplified this required a free propagation of tidal waves from the open ocean through the paratethys into this embayment since all seaways towards the mediterranean were closed during the early eggenburgian the only connection between the north hungarian bay and open marine waters which allowed the transmission of tidal waves was the outlet towards the east slovakian basin in the northeast the presence of tide influenced deposits in the north hungarian bay implies that tidal waves entered the eastern paratethys from the east through a wide passage other examples of lower miocene tide influenced deposits in the mediterranean and paratethian regions are reported from different periods in these cases amplification of tidal motions in various embayments and straits also occurred because of the local basin morphology it is demonstrated that significant palaeogeographic changes during the early miocene resulted in changes of current pathways and related shifts of loci of tide influenced deposition

lower cretaceous tides revealed by cross bedding with mud drapes the sand dominated folkestone beds widely exposed around the weald of south east england are of upper aptian to lower albian lower cretaceous age and range in thickness up to 84 m refs 1 3 their content of ammonites bivalves and sponges indicates a marine origin while their relative coarseness and the incorporation of drifted timber point to a shallow water deposition near land one striking sedimentary facies is formed by medium to coarse grained cross bedded sands in which several foreset and or bottomset surfaces support mud drapes although it was suggested4 that this facies may have been formed by the storm induced movement of sand waves i now consider that the facies is best explained by the migration of sand waves under the influence of strongly asymmetrical tides and that the mud drapes are formed at slack water a model of this process has been described elsewhere5 and i now describe measurements of a section which supports my earlier conjecture6that the separation of the mud drapes is systematically related to the phase of the spring neap tidal cycle at the time of deposition although criteria for recognizing tidal deposits have long been available it has not previously been possible to analyse a series of ancient sediments with a view to characterizing the tidal regime

stratigraphic modeling of foreland basins interpreting thrust deformation and lithosphere rheology the authors incorporate the processes of erosion and deposition in a numerical model to predict the stratal geometries and facies patterns produced during episodic thrusting in a nonmarine foreland basin the resultant stratigraphic record is characterized by a stairstepped facies package in which each retrogradation of facies toward the thrust marks the onset of a thrusting event the retrogradation of facies coincides with the migration of the forebulge toward the thrust and the generation of an erosional unconformity in the past changes in basin wavelength during basin evolution have been interpreted to record viscoelastic relaxation of the lithosphere this model suggests that changes in basin wavelength are a natural consequence of the interplay between thrust and sediment loading on an elastic lithosphere

a case of rapid rock riverbed incision in a coseismic uplift reach and its implications abstract during the 1999 chi chi earthquake m w 7 6 in taiwan the coseismic displacement induced fault scarps and a pop up structure in the taan river the fault scarps across the river experienced maximum vertical slip of 10 m which disturbed the dynamic equilibrium of the fluvial system as a result rapid incision in the weak bedrock with a maximum depth of 20 m was activated within a decade after its armor layer was removed this case provides an excellent opportunity for closely tracking and recording the progressive evolution of river morphology that is subjected to coseismic uplift based on multistaged orthophotographs and digital elevation model dem data the process of morphology evolution in the uplift reach was divided into four consecutive stages plucking is the dominant mechanism of bedrock erosion associated with channel incision and knickpoint migration the astonishingly high rate of knickpoint retreat kpr as rapid as a few hundred meters per year may be responsible for the rapid incision in the main channel the reasons for the high rate of kpr are discussed in depth the total length of the river affected by the coseismic uplift is 5 km 1 km in the uplift reach and 4 km in the downstream reach the downstream reach was affected by a reduction in sediment supply and increase in stream power the kpr cut through the uplift reach within roughly a decade further significant flooding in the future will mainly cause widening instead of deepening of the channel

revealing coseismic displacements and the deformation zones of the 1999 chi chi earthquake in the tsaotung area central taiwan using digital cadastral data 1 the 1999 chi chi taiwan earthquake mw 7 6 was the largest earthquake to strike taiwan in the twentieth century this earthquake is associated with a 100 km long surface rupture in order to reveal the details of displacement near the surface rupture we use a digital cadastral system to calculate coseismic displacement around the tsaotung area central taiwan the digital cadastral system was originally conceived to survey land and building boundaries in the tsaotung area taiwan authorities have taken digital cadastral measurements before and after the chi chi earthquake the cadastral system affords high density control points that reach 1421 points km2 a system denser than that of the gps accuracy is to within 11 cm a level that is higher than spot imaging and one that allows us to study surface deformation in detail coseismic displacement is 4 3 4 6 m at distance from the surface rupture and decreases to 3 4 m near the surface rupture the azimuth of horizontal displacements is 310 315 and rotates to 280 305 near the surface rupture this produced a compression left lateral deformation zone with 10 3 compression strain near the surface rupture coseismic displacement of the footwall is 1 1 2 m in 110 which is similar to that from using gps data in the tsaotung thrust slice we observed that the azimuth of horizontal displacement rotates from a nw trend to a south trend as a result of slip partitioning and gravity slide effect

slip vectors of the surface rupture of the 1999 chi chi earthquake western taiwan about 100 slip vectors were surveyed along the 1999 chi chi earthquake rupture 100 km long western taiwan to understand the coseismic reverse faulting processes the surveyed slip azimuths vary locally over 80 where the rupture is irregular or associated with flexure even where the rupture is straight and has consistent slip azimuths the fault scarp heights horizontal slips and fault dip angles oscillate in a distance of hundreds of meters along the rupture despite these local variations the net slip up to 11 5 m vertical and horizontal slips are significant greater in the north on which maximum shortening 6 m by pure thrust and strike slip 8 m by left lateral fault occur in association with the bend of the rupture the slip azimuths also progressively rotate from north northwest in the north to west southwest in the south these patterns generally agree with those revealed by gps surveys except that the slips by gps in the south move to the west northwest and have values unexpectedly smaller than our measurements our obtained sw directed slips resulted in dominantly right lateral faulting up to 2 4 m where the rupture ends to the southeast this however does not correspond to focal mechanisms of any main shocks or aftershocks

two phase stratigraphic model of foreland basin sequences application of flexural models to nonmarine foreland basin evolution indicates that two different stratigraphic styles of basin fill may develop over time basin subsidence is most rapid during times of thrust load emplacement associated sedimentation is coarse grained immediately adjacent to the thrust front and grades rapidly into fine grained deposits that cover most of the basin the distal part of the basin may also contain deposits derived from streams that flow from beyond the basin toward the thrust belt subsequent removal of the thrust load by erosion and other processes results in flexural rebound of the thrust belt and adjacent foreland basin during this postorogenic phase of adjustment a regional unconformity develops in the proximal part of the foreland basin proximal deposits along with thrust derived sediment are redeposited in the distal foreland basin and beyond this two phase model of foreland sedimentation predicts that coarsening upward sequences in the proximal and distal parts of the basin have reciprocal significance the proximal sequence represents thrust belt advance whereas the distal sequence represents thrust belt cessation

the mid hungarian line a zone of repeated tectonic inversions abstract the mid hungarian line is a major tectonic feature of the intra carpathian area separating two terranes of different origin and tectonic structure although this tectonic line was known from borehole records it has not been described in seismic sections the study presents interpreted seismic lines crossing the supposed trace of the mid hungarian line these seismic sections show north dipping normal faults and thrust faults as well as cross cutting young strike slip faults a complex tectonic history is deduced including intra oligocene early miocene thrusting middle miocene extension local late miocene inversion and late miocene pliocene normal faulting and left lateral wrenching in the light of our seismic study we think that the best candidate for the mid hungarian line is a north dipping detachment fault beneath large masses of neogene volcanics the auxiliary structures to the north seen on seismic sections suggest that it moved as a south vergent thrust fault during the palaeogene early miocene which later was reactivated as a set of normal faults the northern alcapa unit overrode the southern tisza dacia unit along this fault zone the same relative positions are observed in the northern termination of the line other structures along the supposed trace of the line are north dipping normal or strike slip faults which frequently were reactivated as smaller thrust faults during the late neogene palaeogene early miocene thrusting along the line might be the result of the opposite tertiary rotations of the two major units as suggested by palaeomagnetic measurements and earlier models

detailed surface co seismic displacement of the 1999 chi chi earthquake in western taiwan and implication of fault geometry in the shallow subsurface the northern segment of the chelungpu fault shows an unusually large co seismic displacement from the event of the mw 7 6 chi chi earthquake in western taiwan part of the northern segment near the fengyuan city provides an excellent opportunity for characterizing active thrust related structures due to a dense geodetic benchmark network we reproduced co seismic deformation patterns of a small segment of this chelungpu fault using 924 geodetic benchmarks according to the estimated displacement vectors we identified secondary deformations such as local rigid block rotation and significant shortening within the hanging wall the data set also allows us to determine accurately a 3d model of the thrust fault geometry in the shallow subsurface by assuming simple relations between the fault slip and the horizontal and vertical displacements at the surface the predicted thrust geometry is in good agreement with borehole data derived from two drilling sites close to the study area the successful prediction supports our assumptions of rigid displacement and control of displacement in the hanging wall by the fault geometry being useful first approximations

investigation of the records of earthquake slip in carbonaceous materials from the taiwan chelungpu fault by means of infrared and raman spectroscopies this research was supported by a grant in aid for young scientists a from the japan ministry of education science sports and culture 23684039 2013

preseismic deformation and coseismic displacements associated with the 1999 chi chi taiwan earthquake the destructive 1999 chi chi taiwan earthquake m w 7 5 produced an approximately 100 km long surface rupture mostly along the previously recognized north south trending chelungpu fault preseismic deformation in central taiwan is realized from annually repeated global positioning system gps data acquired during the 1992 1999 period the total wnw ese shortening rate in the vicinity of the epicentral region that is from the west coast to the western boundary of the central range is up to 25 mm yr the crustal deformation before the chi chi earthquake was essentially a uniaxial compressional strain of 0 36 strain yr in the direction of 114 the gps measurements taken 0 2 2 7 yr before and within 3 months after the mainshock were utilized to estimate the coseismic displacements horizontal movements of 1 1 9 1 m in the nw nnw directions are observed on the hanging wall eastern side of the fault there is a northward increasing trend in the magnitude of the displacement vectors and a dramatic change in the direction of about 50 toward the east along the fault strike in contrast much smaller se see movements of 0 1 1 5 m are found on the footwall western side of the fault the gps data show 2 4 10 1 m of total horizontal offsets across the chelungpu fault vertical offsets of 1 2 4 4 m with the eastern side up are also observed along the surface rupture the uplift on the hanging wall decreases rapidly toward the east it becomes subsidence at sun moon lake and in the puli wushe area the stations on the footwall show subsidence of 0 02 0 26 m the width of the uplift zone increases from about 10 km in the south to approximately 30 km in the north manuscript received 13 october 2000

sequence stratigraphy and paleogene tectonic evolution of the transylvanian basin romania eastern europe abstract the transylvanian basin of romania belongs to the 800 400 km wide pannonian domain of the european alpine megasuture bordered to the east and the north by the carpathians it represents a digitation of the epicontinental tethyan seaways locally connected during the palaeogene to the peripheral foredeep troughs during that time it was filled up by a 500 m thick sediment pile organized into three shallow marine and non marine facies alternations each evolved from alluvial fans to restricted marine and outer marine environments they are dated from lutetian to chattian times the study is focused on the lowermost alternation onlapping the basal post maastrichtian unconformity this alternation consists of the superimpossition of a thick retrogradational and a thin progradational depositional system the retrogradational depositional system grades upwards from stacked fault controlled deposits of alluvial fan ephemeral stream salina and sabkha and restricted marine bioclastic shales the progradational depositional system is composed of outer marine to estuarine sandstones and shales the two depositional systems are bounded at their tops by two baselevel change unconformities underlain by highly mobile low relief sandstone bodies that were deposited in shoal belts these two unconformities mark significant changes in the regime of the subsidence these are respectively a baselevel rise or drowning unconformity where the shoal deposits were associated with oolitic ironstones and glauconitic shales that typify basin starvation during a period of maximum basin drowning and a baselevel fall or uplifting unconformity where the bioclastic shoal deposits were buried by alluvial flood plain deposits that characterize periods of relief rejuvenation tentatively attributed to compressive events this bimodal succession is interpreted in terms of underfilled overfilled stages related to intraplate tectonic deformation the underfilled stage corresponds to the fault controlled drowning of the basin and the overfilled stage to the increasing flexural rigidity of the substrate culminating in differential uplift in the area three of these successions comprise the palaeogene sedimentary record of the transylvanian basin they attest to a large scale pulsating evolution of this continental microplate during its northward migration towards the european plate

deciphering cumulative fault slip vectors from fold scarps relationships between long term and coseismic deformations in central western taiwan we document the 30 ka cumulative slip history and long term slip vector azimuth on the northern chelungpu fault based on a series of fault bend folded alluvial terraces and draw quantitative relationships between geological structure deformation observed from the geomorphology and coseismic displacements during the 1999 mw 7 6 chi chi earthquake in our study area three main terrace levels show progressive folding by kink band migration in relation to the underlying fault geometry forming a main n s fold scarp up to 193 m high and secondary e w scarps detailed analysis using 5 m resolution digital elevation model allows us to characterize the scarp morphology and quantify the deformation parameters namely terrace heights fold scarp relief and fold limb width and slope angle the 3 d deformation of the highest terrace dated by optically stimulated luminescence at 30 2 4 0 ka enables to simultaneously determine amplitude and azimuth of the long term slip vector based on scarp relief the long term slip vector oriented n338 6 is found to parallel the chi chi coseismic displacements in this area cumulative slip and dating results yield a constant slip rate of 17 7 2 2 mm a in the direction n338 6 late quaternary shortening rates observed at four sites vary along strike in a similar way to chi chi coseismic displacements together with the collinearity of long term and coseismic slip vectors at our study site this suggests that chi chi earthquake is a characteristic earthquake for the chelungpu thrust with recurrence interval 470 years we also discuss implications for the regional and long term distribution of shortening in the central western foothills