the east anatolian fault zone seismotectonic setting and spatiotemporal characteristics of seismicity based on precise earthquake locations 1 the east anatolian fault zone eafz represents a plate boundary extending over 500 km between the arabian and anatolian plates relative plate motion occurs with slip rates ranging from 6 to 10 mm yr and has resulted in destructive earthquakes in eastern turkey as documented by historical records in this study we investigate the seismic activity along the eafz and fault kinematics based on recordings from a densified regional seismic network providing the best possible azimuthal coverage for the target region we optimize a reference 1 d velocity model using a grid search approach and re locate hypocenters using the double difference earthquake relocation technique the refined hypocenter catalog provides insights into the kinematics and internal deformation of the fault zone down to a resolution ranging typically between 100 and 200 m the distribution of hypocenters suggests that the eafz is characterized by ne sw and e w oriented sub segments that are sub parallel to the overall trend of the fault zone faulting mechanisms are predominantly left lateral strike slip and thus in good correlation with the deformation pattern derived from regional gps data however we also observe local clusters of thrust and normal faulting events respectively while normal faulting events typically occur on ns trending subsidiary faults thrust faulting is restricted to ew trending structures this observation is in good accordance with kinematic models proposed for evolving shear zones the observed spatiotemporal evolution of hypocenters indicates a systematic migration of micro and moderate sized earthquakes from the main fault into adjacent fault segments within several days documenting progressive interaction between the major branch of the eafz and its secondary structures analyzing the pre versus post seismic phase for m 5 events we find that aftershock activities are initially spread to the entire source region for several months but start to cluster at the central part of the main shock rupture thereafter

interseismic strain accumulation across the north anatolian fault from envisat insar measurements 1 the north anatolian fault naf is a major feature of middle eastern tectonics and several previous insar studies have measured interseismic deformation across the fault all previous studies however have used sar data acquired from a single line of sight los direction leading to large uncertainties on model parameters and necessitating several modelling assumptions to be made we have measured interseismic deformation across the naf using both ascending and descending sar data for the first time an aim that has previously been limited by the availability of ascending data by using sar data from two look directions we have been able to reduce the range of uncertainties in slip rate and locking depth from previous studies by 60 and by assuming no vertical motion across the fault we estimate both fault normal and fault parallel motion these results support other evidence for predominantly horizontal strike slip motion on the naf our data are consistent with a slip rate of 20 26 mm yr below a locking depth of 13 5 25 km for the naf

energetics of bottom ekman layers during buoyancy arrest abstractturbulent bottom ekman layers are among the most important energy conversion sites in the ocean their energetics are notoriously complex in particular near sloping topography where the feedback between cross slope ekman transports buoyancy forcing and mixing affects the energy budget in ways that are not well understood here the authors attempt to clarify the energy pathways and different routes to mixing using a combined theoretical and modeling approach the analysis is based on a newly developed energy flux diagram for turbulent ekman layers near sloping topography that allows for an exact definition of the different energy reservoirs and energy pathways using a second moment turbulence model it is shown that mixing efficiencies increase for increasing slope angle and interior stratification but do not exceed the threshold of 5 except for very steep slopes where the canonical value of 20 may be reached available potential energy generated by cross slope advection may equal up to

lower crustal structure in northern california implications from strain rate variations following the 1906 san francisco earthquake 1 it is well known that geodetic data from a single instant in time cannot uniquely characterize structure or rheology beneath active seismogenic zones nevertheless comparison of spatial and temporal variations in deformation rate with time dependent mechanical models can place valuable constraints on fault zone geometry and rheology we consider postseismic strain rate transients by comparing geodetic data from north of san francisco bay obtained between 1906 and 1995 to predictions from viscoelastic finite element models models include 1 an elastic plate over a viscoelastic half space 2 distributed shear within a viscoelastic layer 3 discrete shear zones within an otherwise elastic layer 4 discrete shear zones in combination with distributed viscoelastic shear and 5 midcrustal detachment surfaces we vary as applicable locking depth elastic thickness depth to the top and bottom of the distributed shear layer distributed shear relaxation time discrete shear zone relaxation time and discrete shear zone width the best fitting physically reasonable elastic plate over viscoelastic half space models 1 do a poor job simultaneously predicting spatial and temporal variations in the data the best fitting distributed shear models 2 do a poor job predicting spatial variations in the deformation rate although they fit the geodetic data recent findings from seismic reflection refraction studies in northern california argue against models with shallow subhorizontal detachments 5 models incorporating discrete shear zones 3 4 provide the best fit to the geodetic data and are consistent with seismic studies that argue for discrete fault zones extending through the entire crust

interseismic strain accumulation and the earthquake potential on the southern san andreas fault system the southern section of the san andreas fault is the only part of the fault that hasn t ruptured in historic times for this reason it is believed to pose the largest seismic risk in california although whether tectonic stress is actually accumulating there is a topic of heated debate using data from radar interferometry satellites yuri fialko has produced a detailed map of surface deformation in the area that shows that elastic stress is accumulating at a fairly high rate during the past 300 years a displacement of 6 to 9 metres has built up this suggests that the southern san andreas fault is nearing the end of the interseismic phase of the earthquake cycle and that increased seismic activity of some kind can be expected the san andreas fault in california is a mature continental transform fault that accommodates a significant fraction of motion between the north american and pacific plates the two most recent great earthquakes on this fault ruptured its northern and central sections in 1906 and 1857 respectively the southern section of the fault however has not produced a great earthquake in historic times for at least 250 years assuming the average slip rate of a few centimetres per year typical of the rest of the san andreas fault the minimum amount of slip deficit accrued on the southern section is of the order of 7 10 metres comparable to the maximum co seismic offset ever documented on the fault1 2 here i present high resolution measurements of interseismic deformation across the southern san andreas fault system using a well populated catalogue of space borne synthetic aperture radar data the data reveal a nearly equal partitioning of deformation between the southern san andreas and san jacinto faults with a pronounced asymmetry in strain accumulation with respect to the geologically mapped fault traces the observed strain rates confirm that the southern section of the san andreas fault may be approaching the end of the interseismic phase of the earthquake cycle

interseismic strain localization in the san jacinto fault zone we investigate interseismic deformation across the san jacinto fault at anza california where previous geodetic observations have indicated an anomalously high shear strain rate we present an updated set of secular velocities from gps and insar observations that reveal a 2 3 km wide shear zone deforming at a rate that exceeds the background strain rate by more than a factor of two gps occupations of an alignment array installed in 1990 across the fault trace at anza allow us to rule out shallow creep as a possible contributor to the observed strain rate using a dislocation model in a heterogeneous elastic half space we show that a reduction in shear modulus within the fault zone by a factor of 1 2 1 6 as imaged tomographically by allam and ben zion geophys j int 190 1181 1196 2012 can explain about 50 of the observed anomalous strain rate however the best fitting locking depth in this case 10 4 1 3 km is significantly less than the local depth extent of seismicity 14 18 km we show that a deep fault zone with a shear modulus reduction of at least a factor of 2 4 would be required to explain fully the geodetic strain rate assuming the locking depth is 15 km two alternative possibilities include fault creep at a substantial fraction of the long term slip rate within the region of deep microseismicity or a reduced yield strength within the upper fault zone leading to distributed plastic failure during the interseismic period

paleoseismology of the palu lake hazar segment of the east anatolian fault zone turkey the east anatolian fault zone eafz is among the most important active continental transform fault zones in the world as testified by major historical and minor instrumental seismicity the first paleoseismological exploratory trenching study on the eafz was done on the palu lake hazar segment plhs which is one of the six segments forming the fault zone in order to determine its past activity and to assess its earthquake hazard the results of trenching indicate that the latest surface rupturing earthquakes on this segment may be the ms 7 1 1874 and ms 6 7 1875 events and there were other destructive earthquakes prior to these events the recurrence interval for a surface rupturing large m 7 earthquake is estimated as minimum 100 35 and maximum 360 years estimates for the maximum possible paleoearthquake magnitude are mw 7 1 7 7 for the palu lake hazar segment based on empirical magnitude fault rupture relations an alluvial fan dated 14 475 15 255 cal years bp as well as another similar age fan with an abandoned stream channel on it are offset in a left lateral sense 175 and 160 5 m respectively indicating an average slip rate of 11 mm year because 127 years have elapsed since the last surface rupturing event this slip rate suggests that 1 4 m of left lateral strain has accumulated along the segment ignoring possible creep effects folding and other inelastic deformation a 2 5 ma age for the start of left lateral movement on the segment and in turn the eafz is consistent with a slip rate of 11 mm year and a previously reported 27 km total left lateral offset the cumulative 5 6 mm year vertical slip rate near lake hazar suggests a possible age of 148 178 ka for the lake our trenching results indicate also that a significant fraction of the slip across the eafz zone is likely to be accommodated seismically the present seismic quiescence compared with the past activity paleoseismic and historic indicate that the eafz may be locked and accumulating elastic strain energy but could move in the near future

sediment pumping by tidal asymmetry in a partially mixed estuary 1 observations collected at two laterally adjacent locations are used to examine the processes driving sediment transport in the partially mixed york river estuary estimates of sediment flux are decomposed into advective and pumping components to evaluate the importance of tidal asymmetries in turbulent mixing at the instrumented location in the estuarine channel a strong asymmetry in internal mixing due to tidal straining is documented with higher values of eddy viscosity occurring during the less stratified flood tide as a result of this asymmetry more sediment is resuspended during the flood phase of the tide resulting in up estuary pumping of sediment despite a net down estuary advective flux at the instrumented location on the adjacent shoal where no pronounced tidal asymmetry in internal mixing was found both the pumping flux and advective flux were directed down estuary the down estuary pumping of sediment on the shoal appears to be driven by asymmetries in bed stress the impact of tidal asymmetries in bed stress at the channel location was negated because the amount of sediment available for resuspension was limited as a result the pumping flux was dominated by the overlying asymmetries in internal mixing the asymmetries in stratification appear to exert an important control on the vertical distribution of sediment by both impacting the eddy diffusivity as well as the fall velocity during the more turbulent flood tide the fall velocities are smaller suggesting the kolmogorov microscale is setting the upper bound on floc diameter

influence of the earthquake cycle and lithospheric rheology on the dynamics of the eastern california shear zone the eastern california shear zone is bounded by the high heat flow region of the basin and range province and the low heat flow region of the sierra nevada block this difference in thermal state influences the rheology of the lower crust upper mantle resulting in a viscosity contrast between the two regions we analyze the effect of such a contrast on the kinematics and dynamics of the shear zone with numerical models this viscosity contrast drives asymmetric strain accumulation in the upper crust producing an asymmetric surface velocity field an additional consequence of this strain pattern is the potential for asymmetric co seismic displacement during an earthquake

residual transport of suspended material by tidal straining near sloping topography abstracttidal straining is known to have an important impact on the generation of residual currents and the transport of suspended material in estuaries and the coastal ocean essential for this process is an externally imposed horizontal density gradient typically resulting from either freshwater runoff or differential heating here it is shown that near sloping topography tidal straining may effectively transport suspended material across isobaths even if freshwater runoff and differential heating do not play a significant role a combined theoretical and idealized modeling approach is used to illustrate the basic mechanisms and implications of this new process the main finding of this study is that for a wide range of conditions suspended material is transported upslope by a pumping mechanism that is in many respects similar to classical tidal pumping downslope transport may also occur however only for the special cases of slowly sinking material in the vicinity of slopes with a slope angle la

why the 2002 denali fault rupture propagated onto the totschunda fault implications for fault branching and seismic hazards 1 the propagation of the rupture of the mw7 9 denali fault earthquake from the central denali fault onto the totschunda fault has provided a basis for dynamic models of fault branching in which the angle of the regional or local prestress relative to the orientation of the main fault and branch plays a principal role in determining which fault branch is taken geoearthscope lidar and paleoseismic data allow us to map the structure of the denali totschunda fault intersection and evaluate controls of fault branching from a geological perspective lidar data reveal the denali totschunda fault intersection is structurally simple with the two faults directly connected at the branch point 227 2 km east of the 2002 epicenter the 2002 rupture diverges southeast to become the totschunda fault we use paleoseismic data to propose that differences in the accumulated strain on each fault segment which express differences in the elapsed time since the most recent event was one important control of the branching direction we suggest that data on event history slip rate paleo offsets fault geometry and structure and connectivity especially on high slip rate short recurrence interval faults can be used to assess the likelihood of branching and its direction analysis of the denali totschunda fault intersection has implications for evaluating the potential for a rupture to propagate across other types of fault intersections and for characterizing sources of future large earthquakes

stratigraphic sequences and their chronostratigraphic correlation abstract the exxon sequence models of posamentier and coworkers incorporate two concepts which i question they suggest that rivers grade to a bayline but evidence from modern major rivers indicates that they do not they also proposed that fluvial sedimentary accomodation space is generated by the seaward shift in equilibrium profiles during sea level fall but this is too simplistic a model based on the use of schematic continental margin configurations which do not incorporate real slope and relief data in most cases a fall in base level leads to deltaic progradation and upstream fluvial incision most coastal plain fluvial wedges result from two processes sea level rise with the drowning and filling of estuaries and active source area tectonism major tectonic events adjacent to foreland basins such as terrane collisions lead to the development of sequences of third order type duration approximately 1 15 m y changes in intraplate stress regimes resulting from changes in regional plate kinematics have a similar episodicity and can be shown to be responsible for some third order cycles on extensional continental margins examination of the chronostratigraphic basis of the mesozoic cenozoic cycle chart of haq and coworkers reveals internal inconsistencies and an unrealistic downplaying of the built in potential for error this chart is not an approved global standard and it should be used with extreme caution

particle trapping in estuarine tidal flows particle trapping in estuarine turbidity maxima etm is caused primarily by convergent mean and or tidal fluxes of sediment the result is an approximately bell shaped along channel distribution of vertically integrated tidal cycle mean suspended sediment concentration observations from the columbia river estuary suggest that 1 strong two layer or internal along channel residual and overtide flows are generated by time varying stratification and 2 correlations between the near bed velocity and the suspended sediment fields at these frequencies are important in landward transport of sediment a new spatially and temporally integrated form of the sediment conservation equation has been derived to analyze this trapping process time changes in tidally averaged sediment concentration between two estuarine cross sections can be shown to be related to the divergence of the seaward river flow transport the divergence of velocity shear sediment stratification correlations for the mean flow and each tidal constituent and net erosion or deposition at the bed vertically integrated variables other than seaward river transport are absent from this integrated balance analysis of sediment fluxes using this balance supports the idea that internal residual and overtide circulations are primarily responsible for the landward sediment transport on the seaward side of etm found near the upstream limits of salinity intrusion the balance also shows that attempts to represent fluxes causing trapping of sediment in an etm as a product of a time mean vertically integrated along channel gradient and a diffusivity inevitably lead to the appearance of countergradient transport and thus a negative diffusivity on the seaward side of the etm this result occurs because the trapping process is inherently nonlinear and at least two dimensional and because a one dimensional representation is physically unrealistic

recent advances in sar interferometry time series analysis for measuring crustal deformation abstract synthetic aperture radar sar interferometry is a technique that permits remote detection of deformation at the earth s surface and has been used extensively to measure displacements associated with earthquakes volcanic activity and many other crustal deformation phenomena analysis of a time series of sar images extends the area where interferometry can be successfully applied and also allows detection of smaller displacements through the reduction of error sources here we review recent advances in time series sar interferometry methods that further improve accuracy this is particularly important when constraining displacements due to processes with low strain rates such as interseismic deformation we include examples of improved algorithms applied to image deformation associated with the 2010 eruption of eyjafjallajokull volcano in iceland slow slip on the guerrero subduction zone in mexico and tectonic deformation in western anatolia turkey

viscoelastic coupling model of the san andreas fault along the big bend southern california the big bend segment of the san andreas fault is the 300 km long segment in southern california that strikes about n65 w roughly 25 counterclockwise from the local tangent to the small circle about the pacific north america pole of rotation the broad distribution of deformation of trilateration networks along this segment implies a locking depth of at least 25 km as interpreted by the conventional model of strain accumulation continuous slip on the fault below the locking depth at the rate of relative plate motion whereas the observed seismicity and laboratory data on fault strength suggest that the locking depth should be no greater than 10 to 15 km the discrepancy is explained by the viscoelastic coupling model which accounts for the viscoelastic response of the lower crust thus the broad distribution of deformation observed across the big bend segment can be largely associated with the san andreas fault itself not subsidiary faults distributed throughout the region the working group on california earthquake probabilities 1995 in using geodetic data to estimate the seismic risk in southern california has assumed that strain accumulated off the san andreas fault is released by earthquakes located off the san andreas fault thus they count the san andreas contribution to total seismic moment accumulation more than once leading to an overestimate of the seismicity for magnitude 6 and greater earthquakes in their type c zones

rupture characteristics of the a d 1912 murefte ganos earthquake segment of the north anatolian fault western turkey abstract the ganos fault is the westernmost segment of the north anatolian fault naf that generated the 9 august 1912 murefte ganos earthquake mw 7 4 we study the 1912 earthquake characteristics using co seismic fault slip and fault segmentation coupled with an analysis of historical seismic records surface ruptures with small releasing and restraining structures and 1 5 to 5 5 m right lateral offsets have been measured at 45 sites of the onland 45 km long fault section similar structures are delineated by fresh fault scarps and prominent pull apart basins in the sea of marmara and saros bay a second shock with mw 6 8 occurred on 13 september 1912 implying 20 to 40 km long rupture the damage distribution and analysis of seismic records suggest an epicenter located further west near saros bay which indicates the location of western termination of the 9 august rupture our modeling of historical seismic records reveals a relative source time function between the two events and indicates a 40 second rupture duration in agreement for a 120 30 km long fault rupture for the 9 august shock an estimated total rupture length of 150 30 km for the two earthquakes combined with onshore and offshore fault segmentation allow us to better constrain the western limit of the marmara sea seismic gap and related potential for producing a large earthquake that was sharply increased by the devastating 1999 izmit earthquake in the east

earthquake faulting as a structural process abstract structural geology is concerned with the history of movement in the earth s crust and the processes by which displacements occur in the upper one third to one half of deforming continental crust displacement is accommodated largely by seismic slip increments on existing faults it follows that earthquakes and related processes are an integral part of structural geology traditionally structural geologists have been preoccupied with the complexity of the finite deformation within fault zones and with the stress states prevailing at the initiation of faults in intact crust future structural work should be directed more towards understanding the dynamic character of fault reactivation during incremental slip and related effects questions of interest include rheological and geometrical controls on the initiation perturbation and termination of ruptures directivity effects associated with rupture propagation the recognition of structures resulting from repeated stress cycling within seismogenic crust and identification of structural features diagnostic of shear stress levels during faulting structures arising from the inter relationships between slip episodes and induced fluid flow are of special importance because these dynamic fault processes appear influential in the development of much fault hosted mineralization mesothermal gold quartz lodes hosted in high angle reverse shear zones of mixed brittle ductile character form illustrative examples of structures that arguably can only be interpreted by seismo structural analysis embodying the concepts listed above

the acampamento velho formation a lower cambrian bimodal volcanic package geochemical and stratigraphic studies from the cerro do bugio perau and serra de santa barbara cacapava do sul rio grande do sul rs brazil abstract during the late stages of the brasiliano orogenic cycle lower cambrian the camaqua basin was gradually filled by the alkaline trending bimodal volcanic rocks of the acampamento velho alloformation this volcanic package consists of two facies associations the lower one composed of andesites and basaltic andesites and the upper one of rhyolitic rocks the rhyolitic association comprises alternating pyroclastic rocks lapilli tuffs and welded tuffs in the middle section and flows at the top geochemical evidence especially trace elements and ree confirmed the stratigraphic succession proposed herein for the volcanic rocks as well as their co genetic relationships and the fractional crystallization of the felsic sequence the acampamento velho formation seems to have been generated in an extensional regime preceding the collision of the rio de la plata and kalahari continental plates this extensional regime probably occurred during subduction of the adamastor oceanic plate beneath the rio de la plata plate in a retroarc setting

morphology displacement and slip rates along the north anatolian fault turkey 1 geological and geomorphological offsets at different scales are used to constrain the localization of deformation total displacement and slip rates over various timescales along the central and eastern north anatolian fault naf in turkey the naf total displacement is reevaluated using large rivers valleys 80 15 km and structural markers pontide suture 85 25 km tosya vezirkopru basins 80 10 km these suggest a neogene slip rate of 6 5 mm yr over 13 myr the river network morphology shows offsets at a range of scales 20 m to 14 km across the main fault trace and is also used to estimate the degree to which deformation is localized at a smaller scale the morphology associated with small rivers is offset by 200 m along the naf the age of these features can be correlated with the holocene deglaciation and a slip rate of 18 3 5 mm yr is determined this is consistent with a rate of 18 5 mm yr deduced independently from the 14c dating of stream terrace offsets over the short term gps data gives a similar rate of 22 3 mm yr all our results tend to show that most of the deformation between the anatolian and eurasian lithospheric plates has been accommodated along or very close to the active trace of the naf the difference between the neogene and the holocene slip rate may be due to the recent establishment of the current plate geometry after the creation of the naf

fault creep along the southern san andreas from interferometric synthetic aperture radar permanent scatterers and stacking 1 interferometric synthetic aperture radar insar provides a practical means of mapping creep along major strike slip faults the small amplitude of the creep signal 10 mm yr combined with its short wavelength makes it difficult to extract from long time span interferograms especially in agricultural or heavily vegetated areas we utilize two approaches to extract the fault creep signal from 37 ers sar images along the southern san andreas fault first amplitude stacking is utilized to identify permanent scatterers which are then used to weight the interferogram prior to spatial filtering this weighting improves correlation and also provides a mask for poorly correlated areas second the unwrapped phase is stacked to reduce tropospheric and other short wavelength noise this combined processing enables us to recover the near field 200 m slip signal across the fault due to shallow creep displacement maps from 60 interferograms reveal a diffuse secular strain buildup punctuated by localized interseismic creep of 4 6 mm yr line of sight los 12 18 mm yr horizontal with the exception of durmid hill this entire segment of the southern san andreas experienced right lateral triggered slip of up to 10 cm during the 3 5 year period spanning the 1992 landers earthquake the deformation change following the 1999 hector mine earthquake was much smaller 1 cm and broader than for the landers event profiles across the fault during the interseismic phase show peak to trough amplitude ranging from 15 to 25 mm yr horizontal component and the minimum misfit models show a range of creeping locking depth values that fit the data

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

slope induced tidal straining analysis of rotational effects tidal straining is known to be an important factor for the generation of residual currents and transports of suspended matter in the coastal ocean recent modeling studies and field experiments have revealed a new type of slope induced tidal straining in which the horizontal density gradient required for this process is induced by the presence of a slope rather than by river runoff as in classical tidal straining slope induced tidal straining is investigated here with the help of an idealized numerical model and results are compared to a recent data set from the east china sea providing first direct observational evidence the focus of this study is on the effect of rotation that was ignored in previous investigations the model is shown to reproduce the key features of the observations in particular the strain induced generation of unstable stratification in the bottom boundary layer during periods of upslope flow rotation effects are found to significantly reduce the upslope tidal pumping of suspended material and also give rise to a newly identified pumping mechanism that results in a vigorous transport of suspended material along the slope it is shown that slope induced tidal straining is likely to be relevant for a wide range of oceanic slopes exposed to tidal motions

submarine earthquake geology along the north anatolia fault in the marmara sea turkey a model for transform basin sedimentation abstract the submerged portions of the north anatolia fault system beneath the marmara sea were studied with high resolution multibeam bathymetry subbottom profiling and sediment cores the major objectives were to learn about the seismic and tectonic history of the fault from the stratigraphic record at a scale similar to paleoseismic studies on land and to develop tools for submarine earthquake geology that can be applied to fault controlled basins in general we focused on holocene sediment in several marmara sea basins of different sizes the approach was to test whether 1 the depocenters of the larger basins contain a record of all historic ms 7 earthquakes within the marmara sea region 2 the small transform basins record earthquakes that rupture through them 3 vertical and strike slip holocene deformation can be quantified and 4 the effects of an earthquake generally includes both primary structural features due to rupture of the sea floor such as strata offset scarps and tilting as well as secondary effects due to shaking such as mass wasting and gravitational flows we found evidence of earthquakes that we correlate with historic events in 181 ad 740 ad 1063 ad 1343 ad 1509 ad 1766 ad 1894 ad and 1912 ad the geologic evidence is primarily from those basins adjacent to the rupture as inferred from historic data this suggests that coseismic deformation of the sea floor along the rupture is a critical factor in the sedimentary record we propose a qualitative sedimentation model that relates this coseismic deformation to mass wasting of the slope scour of the basin floor seiche motions and homogenite deposition frequent earthquake activity sheds sediments from the flanks contributes to the much thicker sediment on the basin floor and decreases the likelihood of sediment failures in response to normal marine gravity driven processes the surveying techniques and approaches used have therefore the potential of documenting earthquake ruptures of fault segments and to extend the earthquake record far before the known history thus improving hazard evaluations and the fundamental understanding of earthquake process

earthquake imprints on a lacustrine deltaic system the kurk delta along the east anatolian fault turkey deltas contain sedimentary records that are not only indicative of water level changes but also particularly sensitive to earthquake shaking typically resulting in soft sediment deformation structures the kurk lacustrine delta lies at the south western extremity of lake hazar in eastern turkey and is adjacent to the seismogenic east anatolian fault which has generated earthquakes of magnitude 7 this paper reevaluates water level changes and earthquake shaking that have affected the kurk delta combining geophysical data seismic reflection profiles and side scan sonar remote sensing images historical data onland outcrops and offshore coring the history of water level changes provides a temporal framework for the depositional record in addition to the common soft sediment deformation documented previously onland outcrops reveal a record of deformation fracturing tilt and clastic dykes linked to large earthquake induced liquefactions and lateral spreading the recurrent liquefaction structures can be used to obtain a palaeoseismological record five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the east anatolian fault sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator based on radionuclide dating 137cs and 210pb two major sedimentary events were attributed to the ad 1874 1875 east anatolian fault earthquake sequence their sedimentological characteristics were determined by x ray imagery x ray diffraction loss on ignition grain size distribution and geophysical measurements the events are interpreted to be hyperpycnal deposits linked to post seismic sediment reworking of earthquake triggered landslides this article is protected by copyright all rights reserved

lake sediments as natural seismographs a compiled record of late quaternary earthquakes in central switzerland and its implication for alpine deformation central switzerland lies tectonically in an intraplate area and recurrence rates of strong earthquakes exceed the time span covered by historic chronicles however many lakes are present in the area that act as natural seismographs their continuous datable and high resolution sediment succession allows extension of the earthquake catalogue to pre historic times this study reviews and compiles available data sets and results from more than 10 years of lacustrine palaeoseismological research in lakes of northern and central switzerland the concept of using lacustrine mass movement event stratigraphy to identify palaeo earthquakes is showcased by presenting new data and results from lake zurich the late glacial to holocene mass movement units in this lake document a complex history of varying tectonic and environmental impacts results include sedimentary evidence of three major and three minor simultaneously triggered basin wide lateral slope failure events interpreted as the fingerprints of palaeoseismic activity a refined earthquake catalogue which includes results from previous lake studies reveals a non uniform temporal distribution of earthquakes in northern and central switzerland a higher frequency of earthquakes in the late glacial and late holocene period documents two different phases of neotectonic activity they are interpreted to be related to isostatic post glacial rebound and relatively recent re activation of seismogenic zones respectively magnitudes and epicentre reconstructions for the largest identified earthquakes provide evidence for two possible earthquake sources i a source area in the region of the alpine or sub alpine front due to release of accumulated north west south east compressional stress related to an active basal thrust beneath the aar massif and ii a source area beneath the alpine foreland due to reactivation of deep seated strike slip faults such activity has been repeatedly observed instrumentally for example during the most recent magnitude 4 2 and 3 5 earthquakes of february 2012 near zug the combined lacustrine record from northern and central switzerland indicates that at least one of these potential sources has been capable of producing magnitude 6 2 to 6 7 events in the past

provenance of the neoproterozoic marica formation sul rio grandense shield southern brazil petrographic and sm nd isotopic constraints abstract this paper reports the integrated application of petrographic and sm nd isotopic analyses for studying the provenance of the neoproterozoic marica formation southern brazil this unit encompasses sedimentary rocks of fluvial and marine affiliations in the lower fluvial succession sandstones plot in the craton interior and transitional continental fields of the qfl diagram chemical weathering probably caused the decrease of the 147sm 144nd ratios to 0 0826 and 0 0960 consequently lowering originally 2 0 ga tdm ages to 1 76 and 1 81 ga 143nd 144nd ratios are also low 0 511521 to 0 511633 corresponding to negative end present day values 21 8 and 19 6 in the intermediate marine succession sandstones plot in the dissected arc field reflecting the input of andesitic clasts siltstones and shales reveal low 143nd 144nd ratios 0 511429 to 0 511710 end values of 18 1 and 23 6 and tdm ages of 2 16 and 2 37 ga sandstones of the upper fluvial succession have dissected arc and recycled orogen provenance 143nd 144nd isotopic ratios are also relatively low from 0 511487 to 0 511560 corresponding to end values of 22 4 and 21 0 and tdm of 2 07 ga a uniform granite gneissic basement block of paleoproterozoic age with subordinate volcanic rocks is suggested as the main sediment source of the marica formation

relation between continental strike slip earthquake segmentation and thickness of the crust 1 high resolution maps of large continental strike slip earthquake surface ruptures show that they are formed of fault segments these segments are bounded by fault bends step overs or combinations of the two the lowest limit in size for such segments may not be relevant in the understanding of earthquake mechanics as it pertains to the granular properties of fault zones the maximum limit in segment length however is important as it is directly relates to the maximum extent of seismic rupture to measure the length of the segments a new quantitative method based on piecewise linear fitting is developed and is used to automatically retrieve segments from earthquake rupture maps next this approach is tested against a set of ten continental strike slip earthquake ruptures derived from similar high quality maps the test suggests that segments have a maximum length of 18 km independent of regional tectonic setting slip inversions for earthquakes based on seismological and or geodetic data most often are not unique and can show some variability even for one particular event some basic characteristics however such as total moment release or general source geometry seem to persist that are relevant to earthquake mechanics measurements of the maximum horizontal extent of individual slip patches derived from seismic source inversion for strike slip ruptures show that their strike dimension does not increase infinitely with magnitude but instead reaches a maximum value of 25 km these two independent lines of observations complemented by earlier data and analog experiments suggest that it is the thickness of the seismogenic crust that controls the structural scaling of the length of seismic segments and that it is independent of the ultimate size of individual earthquakes

characterization of fault zones there are currently three major competing views on the essential geometrical mechanical and mathematical nature of faults the standard view is that faults are possibly segmented and heterogeneous euclidean zones in a continuum solid the continuum euclidean view is supported by seismic gravity and electromagnetic imaging studies by successful modeling of observed seismic radiation geodetic data and changes in seismicity patterns by detailed field studies of earthquake rupture zones and exhumed faults and by recent high resolution hypocenter distributions along several faults the second view focuses on granular aspects of fault structures and deformation fields the granular view is supported by observations of rock particles in fault zone gouge by studies of block rotations and the mosaic structure of the lithosphere which includes the overall geometry of plate tectonics by concentration of deformation signals along block boundaries by correlation of seismicity patterns on scales several times larger than those compatible with a continuum framework and by strongly heterogeneous wave propagation effects on the earth s surface the third view is that faults are fractal objects with rough surfaces and branching geometry the fractal view is supported by some statistical analysis of regional hypocenter locations by long range correlation of various measurements in geophysical boreholes by the fact that observed power law statistics of earthquakes are compatible with an underlying scale invariant geometrical structure by geometrical analysis of fault traces at the earth s surface and by measurements of joint and fault surfaces topography

asymmetry in elastic properties and the evolution of large continental strike slip faults 1 we use geodetic studies to quantify several cases of significant asymmetry in interseismic and coseismic effects along large continental strike slip faults using simple two dimensional edge dislocation models we first show that asymmetric elastic loading characterizes the present main marmara fault a portion of the north anatolian fault along the northern margin of the sea of marmara the ratio of asymmetry there is about 10 this ratio is even larger about 30 along the northern sumatra fault near lake toba caldera we then examine two profiles near point reyes and point arena across the northern san andreas fault that have been previously proposed as affected by asymmetry both in interseismic and coseismic effects we show that an asymmetry ratio of 1 6 in interseismic loading exists near point arena with the southwest side of the fault being more rigid than the northeast one on the other hand we do not find significant asymmetry for the point reyes profile that was previously described as highly asymmetric we examine coseismic motion during the 1906 earthquake along the same two profiles ratios of 1 2 and 1 7 are found for the point arena and point reyes profiles respectively we discuss the possible causes of asymmetry contrasts in seismic velocity in the brittle portion suggest ratios generally not exceeding 2 5 for the dynamic rigidity in the upper brittle section larger ratios may involve other complex causes such as differences between static and dynamic rigidities contrasts in rheology in the deeper creeping sections and postseismic transients we conclude that asymmetry should be systematically included within the parameters to be inverted when dealing with the mechanics of large scale strike slip faults

flow dynamics at the origin of thin clayey sand lacustrine turbidites examples from lake hazar turkey turbidity currents and their deposits can be investigated using several methods i e direct monitoring physical and numerical modelling sediment cores and outcrops the present study focused on thin clayey sand turbidites found in lake hazar turkey occurring in eleven clusters of closely spaced thin beds depositional processes and sources for three of those eleven clusters are studied at three coring sites bathymetrical data and seismic reflection profiles are used to understand the specific geomorphology of each site x ray thin sections and ct scan imagery combined with grain size geochemical and mineralogical measurements on the cores allow characterization of the turbidites turbidites included in each cluster were produced by remobilization of surficial slope sediment a process identified in very few studies worldwide three types of turbidites are distinguished and compared with deposits obtained in flume studies published in the literature type 1 is made of an ungraded clayey silt layer issued from a cohesive flow type 2 is composed of a partially graded clayey sand layer overlain by a mud cap attributed to a transitional flow type 3 corresponds to a graded clayey sand layer overlain by a mud cap issued from a turbulence dominated flow while the published experimental studies show that turbulence is damped by cohesion for low clay content type 3 deposits of this study show evidence for a turbulence dominated mechanism despite their high clay content this divergence may in part relate to input variables such as water chemistry and clay mineralogy that are not routinely considered in experimental studies furthermore the large sedimentological variety observed in the turbidites from one coring site to another is related to the evolution of a sediment flow within a field scale basin made of a complex physiography that cannot be tackled by flume experiments

interseismic strain accumulation spin up cycle invariance and irregular rupture sequences using models of infinite length strike slip faults in an elastic layer above linear viscoelastic regions we investigate interseismic deformation in the models we investigate interseismic strain accumulation on mature faults is the result of the cumulative effects of all previous ruptures and is independent of the fault loading conditions the time for a fault to spin up to a mature state depends on the rheologies and the fault loading conditions after the model has spun up the temporal variation of shear stresses is determined by the fault slip rate and model rheologies the change in stress during spin up depends on the slip rate rheologies and fault loading conditions but is independent of the magnitude of the initial stress over enough cycles such that the cumulative deformation is block like the average mature interseismic velocities are equal to the interseismic velocities of an elastic model with the same geometry and distribution of shear moduli in a model that has spun up with the fault rupturing periodically the cumulative deformation is block like at the end of each seismic cycle and the interseismic deformation is cycle invariant i e the same in all cycles when the fault ruptures nonperiodically the fault spins up to a mature state that is the same as if the fault had ruptured periodically with the mean slip rate when the fault slip rate within each cycle varies the interseismic deformation evolves toward the cycle invariant deformation determined by the most recent fault slip rate around a fault whose slip rate has been faster slower than average interseismic velocities are larger smaller than the cycle invariant velocities and increase decrease from cycle to cycle

seismogenic zones in eastern turkey an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl018023 shtml http atlas geo cornell edu turkey publications turkelli et al 2003 htm

asperities barriers characteristic earthquakes and strong motion prediction recent results from paleoseismology suggest that earthquakes recurrent on a given fault may often have the same characteristic length and amount of slip stable asperities and barriers which survive many earthquakes can explain these results the activity of volcano usu japan since 1977 which produced a dacite dome with a total upheaval of 180 m offered a great opportunity to study the recurrence behavior of a fault seismologists at hokkaido university revealed a family of repeated earthquakes with nearly the same amount of slip generated from the same fault plane on the crater wall along which the dome moved upward this family can be explained by the existence of a stable asperity on the crater wall and is called the asperity type family they found however another type of family of earthquakes which share the same fault plane but show a great range of variation in the amount of slip the behavior of the latter family can be explained by the presence of weak barriers over a fault plane defined by strong stable barriers and this family is referred to as the barrier type family this type of earthquake model has been used successfully in the interpretation of observed strong motion acceleration spectra from california and the results reveal the stability of local stress drop among different earthquakes the agreement found between local stress drops estimated from strong motion data and those inferred from geological observation supports the possibility for predicting earthquake strong motion directly from geological observation of the causative fault

evidence for an earthquake barrier model from mw 7 8 kokoxili tibet earthquake slip distribution abstract the slip distribution of the mw 7 8 kokoxili tibet 2001 earthquake has been measured at high resolution using optical correlation of satellite images and provides both the parallel and perpendicular components of the horizontal co seismic slip this reveals a variation of the horizontal slip at a scale of 20 km along strike anti correlation of slip parallel and perpendicular to the fault indicates transfer of slip from the horizontal to the vertical component at the ends of segments these features suggest a rupture model with segments separated by strong persistent geometric barriers the unexpected ending of the rupture south of the main fault can be explain by such a structure but bears important implications for the initiation and rupture directivity of the next earthquake

quantifying the contributions of tidal straining and gravitational circulation to residual circulation in periodically stratified tidal estuaries abstract this numerical modeling study quantifies for the first time the contribution of various processes to estuarine circulation in periodically stratified tidal flow under the impact of a constant horizontal buoyancy gradient the one dimensional water column equations with periodic forcing are first cast into nondimensional form resulting in a multidimensional parameter space spanned by the modified inverse strouhal number and the modified horizontal richardson number as well as relative wind speed and wind direction and the residual runoff the along tide momentum equation is then solved for the tidal mean velocity profile in such a way that it is equated to the sum of the contributions of tidal straining resulting from the temporal correlation between eddy viscosity and vertical shear gravitational circulation resulting from the depth varying forcing by a constant horizontal buoyancy gradient wind straining and depth mean residual flow resulting from net freshwater runoff this definitio

a comparison of the sedimentary records of the 1960 and 2010 great chilean earthquakes in 17 lakes implications for quantitative lacustrine palaeoseismology seismically induced event deposits embedded in the sedimentary infill of lacustrine basins are highly useful for palaeoseismic reconstructions recent well documented great megathrust earthquakes provide an ideal opportunity to calibrate seismically induced event deposits for lakes with different characteristics and located in different settings this study used 107 short sediment cores to investigate the sedimentary impact of the 1960 mw 9 5 valdivia and the 2010 mw 8 8 maule earthquakes in 17 lakes in south central chile i e lakes negra lo encanado aculeo vichuquen laja villarrica calafquen pullinque pellaifa panguipulli neltume rinihue ranco maihue puyehue rupanco and llanquihue a combination of image analysis magnetic susceptibility and grain size analysis allows identification of five types of seismically induced event deposits i mass transport deposits ii in situ deformations iii lacustrine turbidites with a composition similar to the hemipelagic background sediments lacustrine turbidites type 1 iv lacustrine turbidites with a composition different from the background sediments lacustrine turbidites type 2 and v megaturbidites these seismically induced event deposits were compared to local seismic intensities of the causative earthquakes eyewitness reports post earthquake observations and vegetation and geomorphology of the catchment and the lake megaturbidites occur where lake seiches took place lacustrine turbidites type 2 can be the result of i local near shore mass wasting ii delta collapse iii onshore landslides iv debris flows or mudflows or v fluvial reworking of landslide debris on the contrary lacustrine turbidites type 1 are the result of shallow mass wasting on sublacustrine slopes covered by hemipelagic sediments due to their more constrained origin lacustrine turbidites type 1 are the most reliable type of seismically induced event deposits in quantitative palaeoseismology because they are almost exclusively triggered by earthquake shaking moreover they most sensitively record varying seismic shaking intensities the number of lacustrine turbidites type 1 linearly increases with increasing seismic intensity starting with no lacustrine turbidites type 1 at intensities between v and vi and reaching 100 when intensities are higher than vii combining different types of seismically induced event deposits allows the reconstruction of the complete impact of an earthquake

recent behavior of the north anatolian fault insights from an integrated paleoseismological data set 1 the north anatolian fault naf is a right lateral plate boundary fault that arcs across northern turkey for 1500 km almost the entire fault progressively ruptured in the 20th century its cascading style indicating that stress from one fault rupture triggers fault rupture of adjacent segments using published paleoseismic investigations this study integrates all of the existing information about the timing of paleoearthquakes on the naf paleoseismic investigation data are compiled into a database and for each site a bayesian ordering constrained age model is constructed in a consistent framework spatial variability of recurrence intervals suggests a spatial pattern in the behavior of earthquakes on the naf that may correspond to the tectonic provinces within the anatolian plate in the west the shear stress associated with the escaping anatolian plate interplays with the tensile stress associated with the aegean extensional province along this western transtensional section we recognize short recurrence intervals and switching between the furcated fault strands the central section of the naf is translational with little influence of fault normal stresses from other tectonic sources this section tends to rupture in unison or close succession the eastern section of the naf is transpressional due to the compressional fault normal stress associated with the indenting arabian plate along this section the recurrence intervals are bimodal which we attribute to variable normal stress although there are other possible causes

sedimentary earthquake records in the izmit gulf sea of marmara turkey abstract sedimentary earthquake records of the last 2400 a including that of the devastating 17 august 1999 izmit earthquake mw 7 4 were studied in cores from the 210 m deep central karamursel basin of the izmit gulf in the eastern sea of marmara using laser grain size physical properties stable o and c isotopes and xrf core scanner analyses and dated by radionuclide and radiocarbon methods the earthquake records are represented by turbidite homogenite mass flow units thu that commonly contain a basal coarse layer a middle laminated silt layer and an overlying homogeneous mud layer the coarse basal part has a sharp and sometimes scoured lower boundary and includes multiple coarse sand silt layers or laminae showing normal size grading multiple coarse layers and occasional bi directional cross bedding suggest deposition from a bed load during water column oscillations or seiche effect the grain size characteristics of the overlaying laminated silt and the homogeneous mud units indicate deposition from weak oscillating currents and homogeneous suspension respectively high mn value just below the base of thus suggests diagenetic enrichment at oxic anoxic redox boundary before the mass flow event sharp decrease in mn with very low values within the thus suggests transient redox conditions following the mass flow variable geochemical compositions of the basal coarse layers indicate different sediment sources for different thus eight sedimentary earthquake records observed in the last 2400 a in the izmit gulf can be confidently correlated with the historical earthquakes of 1999 1509 ad ms 7 2 1296 ad i vii 865 ad i viii 740 ad i viii 268 ad i viii 358 ad i ix and 427 bc this gives an earthquake recurrence time of ca 300 a with the interval between consecutive events ranging from 90 to 695 a

sedimentary impacts of recent moderate earthquakes from the shelves to the basin floor in the western gulf of corinth abstract in seismically active areas long term records of large earthquakes are indispensable to constrain reccurence patterns of large earthquakes in the western corinth rift one of the most active areas in europe in terms of seismicity data about ancient earthquakes are still insufficient despite historical records covering the last two millenia and several studies in onshore paleoseimology in this paper we test the use of offshore sediments from the gulf of corinth to identify sediment failures and tsunamis that have been triggered by historical earthquakes two shelves 40 100 m deep one sub basin 180 m and the basin floor 330 m have been sampled by short gravity cores the cores were analyzed in order to identify and characterize event deposits the age control has been provided by 137cs and 210pb activity measurements showing that the cores represent 2 to 4 centuries of sedimentation in each site sandy event deposits are interbeded in the muddy hemipelagic sedimentation the age of event deposits has been compared to the record of historical earthquakes using new and published macroseismic data this comparison shows temporal coincidence of some event deposits and documented earthquakes with a macroseismic intensity vii in the area e g in 1861 ce 1888 ce and 1909 ce in nearshore shallow water settings the record of event deposits does not exactly fit with the historical record of large earthquakes because too few event deposits are present this may be due to the absence of sediment failures or to a lower preservation of the deposits in such settings in the deepest site in the basin floor the correspondence is better a sandy turbidite probably corresponds to each large earthquake since 1850 ce except one aseismic sediment density flow that occurred at the end of the 20th century surprisingly the ms 6 2 june 15 1995 aigion earthquake is only possibly recorded in one nearshore site on the aigion shelf in the form of a tsunami back wash flow deposit this study showed that moderate earthquakes m 5 8 6 5 can significantly impact marine sediments regarding the evaluation of seismic hazard in the area the basin floor is proposed as a promising site for long term paleoseismology in the gulf of corinth while shallower settings need to be considered more carefully

weak ductile shear zone beneath a major strike slip fault inferences from earthquake cycle model constrained by geodetic observations of the western north anatolian fault zone gps data before and after the 1999 izmit duzce earthquakes on the north anatolian fault zone turkey reveal a preseismic strain localization within about 25 km of the fault and a rapid postseismic transient using 3 d finite element calculations of the earthquake cycle in an idealized model of the crust comprising elastic above maxwell viscoelastic layers we show that spatially varying viscosity in the crust can explain these observations depth dependent viscosity without lateral variations can reproduce some of the observations but cannot explain the proximity to the fault of maximum postseismic velocities a localized weak zone beneath the faulted elastic lid satisfactorily explains the observations if the weak zone extends down to midcrustal depths and the ratio of relaxation time to earthquake repeat time ranges from 0 005 to 0 01 for weak zone widths of 24 and 40 km respectively in the weakened domain and greater than 1 0 elsewhere corresponding to viscosities of 1018 0 3 pa s and greater than 1020 pa s models with sharp weak zone boundaries fit the data better than those with a smooth viscosity increase away from the fault implying that the weak zone may be bounded by a relatively abrupt change in material properties such a change might result from lithological contrast grain size reduction fabric development or water content in addition to any effects from shear heating our models also imply that viscosities inferred from postseismic studies primarily reflect the rheology of the weak zone and should not be used to infer the mechanical properties of normal crust

insar velocity field across the north anatolian fault eastern turkey implications for the loading and release of interseismic strain accumulation we use the persistent scatterer interferometric synthetic aperture radar ps insar technique with the european space agency s envisat and ers sar data acquired on three neighboring descending tracks t350 t078 and t307 to map the interseismic strain accumulation along a 225 km long nw se trending section of the north anatolian fault that ruptured during the 1939 1942 and 1943 earthquakes in eastern turkey we derive a line of sight velocity map of the region with a high spatial resolution and accuracy which together with the maps of earthquake surface ruptures shed light on the style of continental deformation and the relationships between the loading and release of interseismic strain along segmented continental strike slip faults in contrast with the geometric complexities at the ground surface that appear to control rupture propagation of the 1939 event modeling of the high resolution ps insar velocity field reveals a fairly linear and narrow throughgoing shear zone with an overall 20 3 mm yr slip rate above an unexpectedly shallow 7 2 km locking depth such a shallow locking depth may result from the postseismic effects following recent earthquakes or from a simplified model that assumes a uniform degree of locking with depth on the fault a narrow throughgoing shear zone supports the thick lithosphere model in which continental strike slip faults are thought to extend as discrete shear zones through the entire crust fault segmentation previously reported from coseismic surface ruptures is thus likely inherited from heterogeneities in the upper crust that either preexist and or develop during coseismic rupture propagation the geometrical complexities that apparently persist for long periods may guide the dynamic rupture propagation surviving thousands of earthquake cycles

high resolution sequence stratigraphy the east coulee delta alberta abstract the fundamental concept on which sequence stratigraphy is based is that stratal architectures develop in response to the interaction between base level change and sediment flux a small lacustrine fan delta at east coulee alberta illustrates these principles and demonstrates that sequence stratigraphic concepts are scale and time independent this fan delta formed in a matter of days in a roadside drainage ditch as water level rose and then fell changes in the subaqueous space available for sediment to fill i e accommodation resulted in the development of a succession of systems tracts analogous to those formed within sedimentary basins over much longer time frames deposition began during lake level rise with progradation of a fan deltaic wedge accelerating lake level rise resulted in a backstepping of the shoreline and deposition of a transgress systems tract subsequent lake level fall resulted in subaerial exposure of the relatively steep delta front and caused incised valley formation and deposition of a lowstand delta this stratigraphic response to base level fall is typical of lowstand systems tract development on basin margins characterized by high relief slopes e g passive margins further lake level fall resulted in minor additional valley incision and development of a second lowstand delta on a surface characterized by lower relief as lowering water level exposed a flatter physiography this development of lowstand deltas and coa tlines during base level fall constitutes a forced regression of posamentier et al 1990 and is typical of lowstand systems tracts on basin margins characterized by gentle slopes in spite of its small size this example clearly illustrates that sequence stratigraphic principles apply to lacustrine as well as marine settings and at all spatial and temporal scales

a high resolution late holocene lake isotope record from turkey and links to north atlantic and monsoon climate a high resolution proxy record of precipitation and evaporation variability through the past 1700 yr from 18o analysis of a varved lake sequence from central turkey shows rapid shifts between dry periods ad 300 500 and ad 1400 1950 and wetter intervals ad 560 750 and ad 1000 1350 changes are consistent with changes in instrumental and proxy records of the indian monsoon dry summers in the eastern mediterranean being associated with periods of enhanced monsoon rainfall in addition major shifts in the record are coherent with changes in north atlantic winter climate with cold wet periods in the alps occurring at times of dry turkish climate

observed fluxes of water salt and suspended sediment in a partly mixed estuary abstract observations of the residual fluxes of water salt and suspended sediment are presented for seven stations along the tamar estuary the data include measurements over single spring and neap tidal cycles and are generally applicable to medium or high run off conditions surface to bed differences in salinity are typically of the order of several parts per thousand gravitational circulation is an important component of residual flow in the deep lower reaches of the estuary here stokes drift is insignificant in the shallow upper reaches the major residual currents are generated by stokes drift and freshwater inputs data are compared with predictions from hansen and rattray s 1966 model of estuarine circulation salt fluxes due to tidal pumping and vertical shear are directed up estuary at spring tides tidal pumping being dominant tidal pumping of salt is also directed up estuary at neap tides although it is insignificant in the lower reaches where vertical shear dominates tidal pumping of suspended sediment is directed up estuary near the head at spring tides and probably contributes to the formation of the turbidity maximum the existence of the turbidity maximum is predicted using a simplified model of the transport of water and sediment the model shows that an additional mechanism for the existence of the turbidity maximum is an up estuary maximum in the tidal current speeds and thus resuspension in the lower reaches transport of suspended sediment is directed down estuary at both spring and neap tides and sediment is essentially flushed to sea with the fresh water

long lasting seismic repeaters in the central basin of the main marmara fault the main marmara fault mmf which crosses the whole marmara sea is a significant seismic gap along the north anatolian fault here we show that nine long lasting strike slip seismic repeaters exist below the central basin within the seismogenic zone in a 10 km region where deep creep was previously suggested from the analysis of the local seismicity the typical recurrence time is 8 months during the 2008 2015 period the cumulative slip of the repeating sequence appears to be compatible with the regional geodetic slip rate if they are assumed to be part of a large single asperity 10 km the repeaters also exhibit short term crises and are possibly related to bursts of creep

the crustal structure of the east anatolian plateau turkey from receiver functions an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl018192 shtml http atlas geo cornell edu turkey publications zor et al 2003 htm

the 2020 mw 6 8 elazig turkey earthquake reveals rupture behavior of the east anatolian fault the 2020 mw 6 8 elazig earthquake was the largest along the eastern anatolian fault eaf in over a century and so provides valuable insights into its rupture behavior because the eaf is of low to

creeping along the ismetpasa section of the north anatolian fault western turkey rate and extent from insar creeping along the north anatolian fault naf at ismetpasa turkey was discovered some thirty years ago about a decade after the first observations of the phenomenon along the san andreas fault in california however little is known about its lateral extent and rate in order to study its three dimensional nature and rupture characteristics we use synthetic aperture radar interferometry insar and elastic dislocation models compared also with field observations interferograms with temporal baselines ranging between 1 25 and 5 years show that the creeping section starts at the western termination of the 1943 m 7 6 earthquake rupture it continues about 70 km to the west overlapping with the eastern part of the 1944 m 7 3 earthquake rupture offsets along strike indicate a maximum creep rate of 11f3 mm year near the mid point of the creeping section decreasing gradually towards the edges near ismetpasa insar data yield 8f3 mm year of creep rate consistent with recent instrumental triangulation and creepmeter measurements modeling of the insar and gps data suggests that the faultcreep occurs most probably at a shallow depth 0 7 km our analysis combined with previous studies suggests that creeping might have commenced following the 1944 earthquake and thus may be a long lasting but transient slip episode d 2005 elsevier b v all rights reserved

submarine earthquake history of the cinarcik segment of the north anatolian fault in the marmara sea turkey the north anatolian fault naf in the marmara sea is a significant hazard for the city of istanbul the use of paleoseismological data to provide an accurate seismic risk assessment for the area is constrained by the fact that the naf system is submarine thus a history of paleoearthquakes can be inferred only by using marine sediment cores here a record of turbidites was obtained in two cores and used to reconstruct the earthquake history along the cinarcik segment a main branch of the naf klg04 was collected from a berm north of the fault and klg03 was positioned in the cinarcik basin south of the fault the cores were correlated using long term geo chemical variations in the sediment and turbidites deposited simultaneously at both sites were then identified radionuclide measurements suggest the most recent turbi dite was triggered by the 1894 c e m w 7 3 earthquake we conclude that the turbidites identified at both sites are earthquake generated based on their particular sedimento logical and geochemical signatures the correlation of turbidites at berm and basin sites and the match of the most recent turbidite with a nineteenth century historical earthquake to date older turbidites we used carbon 14 and paleomagnetic data to build an oxcal model with a local reservoir correction of 400 50 yr the cinarcik segment is found to have ruptured in 1509 c e sometime in the fourteenth century in 989 c e and in 740 c e with a mean recurrence interval in the range of 256 321 years finally we used the earthquake record obtained to review the rupture history of the adjacent segments over the past 1500 years

seismically triggered organic rich layers in recent sediments from gollukoy lake north anatolian fault turkey abstract multi proxy analyses on the sedimentary sequence of gollukoy lake which is located on the eastern north anatolian fault naf reveals a complete and high resolution paleoseismic record for the last 650 years six sedimentary events are detected in a 3 1 m long piston core they form distinct organic rich intercalations within the background sedimentation which are characterized by strong anomalies on the loss on ignition loi550 and total organic carbon toc profiles as well as by lighter colours on the x ray radiographic images itrax micro xrf core scanner data are also used to contribute to the detection and characterization of the event deposits after the detection of the sedimentary events their temporal correlation with the earthquakes in the historical seismicity catalogue of the naf is tested the youngest event is dated to 1940s by using 210pb and 137cs profiles in sediment which coincides with the 1939 earthquake ms 7 7 on the naf the ages of the older five events are determined based on radiocarbon dating and regional time stratigraphic correlation radiocarbon dating on the bulk sediment samples does not provide reliable results due to hard water effect on the other hand dating on charcoals ephippia of daphnia and phragmite remains significantly improves the results and implies a mean sedimentation rate of 0 28 cm yr based on this preliminary sedimentation rate we show that organic matter content variations through our record correlate with the varve based 18o record of nar lake which is located 350 km southwest of gollukoy lake accordingly high precipitation low evaporation climatic episodes detected in nar lake are represented by higher organic matter content in gollukoy sediments fine tuning the gollukoy loi550 record to the nar 18o record reveals that the ages of the sedimentary events in gollukoy match with well known historical earthquakes that occurred around the lake finally the origin of the organic rich intercalations is discussed based on macroscopic observations and organic geochemistry the events are attributed to reworked organic matter eroded from the lake s littoral zone by seismically induced water oscillations seiche and their subsequent deposition at the middle parts of the lake these seismically induced events are atypical compared to the classic earthquake triggered sedimentary processes in lacustrine environments which are shortly reviewed in order to emphasize the unusual gollukoy lake record

observations of tidal straining within two different ocean environments in the east china sea stratification and near bottom turbulence tidal straining describes the straining effect induced by the vertical shear of oscillatory tidal currents that act on horizontal density gradients it tends to create tidal periodic stratification and modulate the turbulence in the bottom boundary layer bbl here we present observations of current hydrology and turbulence obtained at two mooring stations that are characterized by two typical hydrological environments in the east china sea ecs one is located adjacent to the changjiang river s mouth and the other is located over a sloping shelf which is far from the freshwater sources tidal straining induces a semidiurnal switching between stable and unstable stratification at both stations near bottom high frequency velocity measurements further reveal that the dissipation rate of turbulent kinetic energy tke is highly elevated during periods when unstable stratification occurs a comparison between the tke dissipation rate e and the shear production p further reveals that the near bottom mixing is locally shear induced most of the time except during the unstable stratification period within this period the magnitude of dissipation exceeds the expected value based on the law of the wall by an order of magnitude the buoyancy flux that calculated by the balance method is too small to compensate for the existing discrepancy between the dissipation and shear production another plausible candidate is the advection of tke which may play an important role in the tke budget during the unstable stratification period

microplate model for the present day deformation of tibet 1 site velocities from 349 global positioning system gps stations are used to construct an 11 element quasi rigid block model of the tibetan plateau and its surroundings rigid rotations of five major blocks are well determined and average translation velocities of six smaller blocks can be constrained where data are well distributed the velocity field can be explained well by rigid block motion and fault slip across block boundaries residual misfits average 1 6 mm yr compared to typical one standard deviation velocity uncertainties of 1 3 mm yr any residual internal straining of the blocks is small and heterogeneous however residual substructure might well represent currently unresolved motions of smaller blocks although any smaller blocks must move at nearly the same rate as the larger blocks within which they lie undetected relative motions between them could be significant particularly where there are gaps in gps coverage predicted relative motions between major blocks agree with the observed sense of slip and along strike partitioning of motion across major faults however predicted slip rates across tibet s major strike slip faults are low only 5 12 mm yr a factor of 2 3 smaller than most rates estimated from fault offset features dated by radiometric methods as 2000 to 100 000 year old previous work has suggested that both gps data and low fault slip rates are incompatible with rigid block motions of tibet the results reported here overcome these objections

a 3800 yr paleoseismic record lake hazar sediments eastern turkey implications for the east anatolian fault seismic cycle abstract the east anatolian fault eaf in turkey is a major active left lateral strike slip fault that was seismically active during the 19th century but mostly quiet during the 20th century geodetic data suggests that the fault is creeping along its central part here we focus on its seismic history as recorded in the sediments of lake hazar in the central part of the eaf sediment cores were studied using x ray imagery magnetic susceptibility grain size loss on ignition and x ray fluorescence measurements recurring thin coarse grained sediment units identified as turbidites in all cores were deposited synchronously at two deep study sites the turbidite ages are inferred combining radiocarbon and radionuclide 137cs and 210pb dating in an oxcal model a mean recurrence interval of 190 yrs is obtained over 3800 yrs ages of the recent turbidites correspond to historical earthquakes reported to have occurred along the eaf zone or to paleoruptures documented in trenches just northeast of lake hazar the turbidites are inferred to be earthquake triggered our record demonstrates that lake hazar has been repeatedly subjected to significant seismic shaking over the past 3800 yrs the seismic sources are variable 65 of all turbidites are associated with an eaf source the seismic cycle of central eaf is thus only partly impacted by creep

stratigraphic analysis and depositional evolution of the neoproterozoic marica formation southern brazil constraints from field data and sandstone petrography abstract this paper describes the application of facies analysis and sequence stratigraphic concepts and methods to the neoproterozoic marica formation this unit crops out in the western portion of the sul rio grandense shield which records the brasiliano pan african cycle 900 540 ma in southern brazil the sedimentary package ca 2 500 m thick of the marica formation encompasses sandstones siltstones shales and subordinated conglomerates deposited by fluvial to shallow marine systems along a ne sw trending coastal area these deposits are arranged in three distinct stratigraphic units 1 a lower succession of fluvial origin with southeastward paleocurrent pattern derived from the erosion of a granite gneissic basement uplift 2 an intermediate succession comprising a transgressive regressive marine sequence and 3 an upper succession also of fluvial affiliation with volcanic as well as granite gneissic provenance volcanogenic beds and other volcanism related features are present jointly with the sedimentary rocks as well as abundant volcanogenic clasts that form the framework of sandstones and conglomerates specially upsection the textural immaturity of the sandstones very angular to subangular fragments is remarkable and contrasts with the very good rounding of pebbles and cobbles these features suggest limited transportation of the sedimentary load and reworking of already rounded beach gravel deposits the depositional evolution envisaged here accounts for an overall coastal environment adjacent to an uplifted granite gneissic source area with significant volcanic contribution in terms of sequence stratigraphy the marica formation is considered a high order depositional sequence the marica basin fill subdivided in two lower order sequences

crustal structure of the north anatolian and east anatolian fault systems from magnetotelluric data abstract magnetotelluric mt studies can map subsurface resistivity structure and have located zones of low resistivity high conductivity within major strike slip fault zones worldwide which have been interpreted as regions of elevated fluid content this study describes mt data from the eastern part of the north anatolian and the east anatolian fault systems nafs and eafs and presents the results of the first mt studies of these faults the inversion of the mt data produced 2 d resistivity models which showed that both fault systems are underlain by a broad low resistivity zone that extended into the lower crust however the resistivity beneath the east anatolian fault system was much lower than beneath the eastern part of the north anatolian fault system these conductors begin at a depth of 10 km not at the surface as on the central san andreas fault safs this difference is interpreted as being due to the fact that the eafs and nafs are young fault systems characterized in the upper crust by multiple fault traces as opposed to the safs that has evolved into a single through going fault different stages of the seismic cycle may also influence the resistivity structure although this is difficult to constrain without knowledge of time variations in resistivity structure at each location

temporary seismic quiescence se turkey summary the border zone that is the contact of the arabian plate with the three plates of turkey eurasia and iran to the north has been remarkably aseismic during this century by extending the period of observation backwards in time by a few centuries it is shown that this seismicity is atypical of the long term behaviour of the zone and due to a quiescent period in the activity of the area during the 20th century in turn this implies that short term data alone do not provide a reliable assessment of earthquake hazard

volcanic cycles and setting in the neoproterozoic iii to ordovician camaqua basin succession in southern brazil characteristics of post collisional magmatism the camaqua basin comprises a volcano sedimentary succession located in southernmost brazil and represents a molasse basin formed at the post collisional stage of the brasiliano pan african orogenic cycle in the neoproterozoic iii to ordovician period this basin is one of the most well preserved ancient volcano sedimentary sequences undeformed and unmetamorphic in the world dominantly developed on a continental setting under subaerial conditions it is composed of five major stratigraphic units four of them with a distinct volcanic character from the bottom to the top as 1 marica 2 bom jardim 3 acampamento velho 4 santa barbara and 5 guaritas allogroups a concise sight of geochemical and isotopic rock data is presented as well as stratigraphic correlation and description of rock structures and textures that lead to the identification of their genetic processes the aim of this paper indicating a relation with a coeval plutonism and volcanism that evolved from high k calc alkaline to shoshonitic and ended with a silica saturated sodic alkaline magmatism with a crustal component represented by peraluminous granites volcanic deposits from bottom to top are made mostly of volcanogenic sedimentary deposits succeeded by basic to intermediate lava and pyroclastic flows of shoshonitic affinity followed by intermediate and acid lava flows and ignimbrites of sodic alkaline affinity the last volcanic event is represented by basalt pahoehoe flows probably of mildly alkaline sodic affinity

how can we improve a global ocean tide model at a regional scale a test on the yellow sea and the east china sea a global ocean model has been developed within the context of topex poseidon t p on the basis of a finite element hydrodynamic modeling approach combined with data assimilation based on the representer method the solution produced at global scale represents a spectacular improvement over what was available before the era of t p typically the mean discrepancy between the main tidal components and a hundred in situ tide gauges is 1 7 cm for m2 and 1 cm or less for the other components however the accuracies of this solution and of that produced by different authors within the t p tide working group are all worse near coastlines and over continental shelves this is the case for our finite element solution fes fes94 1 solution over the yellow sea and the east china sea ys ecs where the discrepancy is 33 cm for the m2 tide and 9 cm for the k1 tide when compared to a set of 192 tide gauges distributed along the coastlines this is due largely to the complex geometry of the basin and the limited knowledge of the bathymetry the aim of this paper is to investigate how our fes model can be improved with a dedicated application focused on one of the most energetic coastal basins the ys ecs 180 gigawatts for m2 i e 8 of the global energy dissipated in the whole ocean for this application a finite grid was implemented with a resolution down to 5 km along the coasts and over the continental shelf break particular attention was paid to bathymetry by complementing the etop05 database with regional maps sensitivity tests to the tuning of the bottom friction and the nonlinear interactions between the diurnal and semidiurnal components allow us to investigate the impact of dissipation parameterization and to produce an optimal solution without any data assimilation for nine main components of the tidal spectrum improvement by a factor of 2 m2 distance to the observations is now 17 5 cm global variance of 92 cm and k1 is 4 cm global variance of 21 cm as nonlinear components are significant over these basins the two main quarterdiurnal components are calculated the improvements are explained by five points 1 the choice of a mixed friction 2 a refinement of the mesh 3 a choice of reliable boundary conditions 4 a refined topography and 5 the use of a specific friction coefficient 1 5 10 3 surprisingly the energy budget for the m2 component leads to a dissipation similar to the value estimated by the global fes94 1 this is a major result of this study which leads us to the conclusion that when forcing a regional model with sea level boundary conditions along the open limits the simulated velocity field adjusts to the tuning of friction coefficients in order to dissipate the same amount of energy made available at its open boundaries

lacustrine turbidites as a tool for quantitative earthquake reconstruction new evidence for a variable rupture mode in south central chile understanding the long term earthquake recurrence pattern at subduction zones requires continuous paleoseismic records with excellent temporal and spatial resolution and stable threshold conditions south central chilean lakes are typically characterized by laminated sediments providing a quasi annual resolution our sedimentary data show that lacustrine turbidite sequences accurately reflect the historical record of large interplate earthquakes among others the 2010 and 1960 events furthermore we found that a turbidite s spatial extent and thickness are a function of the local seismic intensity and can be used for reconstructing paleo intensities consequently our multilake turbidite record aids in pinpointing magnitudes rupture locations and extent of past subduction earthquakes in south central chile comparison of the lacustrine turbidite records with historical reports a paleotsunami subsidence record and a marine megaturbidite record demonstrates that the valdivia segment is characterized by a variable rupture mode over the last 900 years including i full ruptures mw 9 5 1960 1575 1319 9 1127 44 ii ruptures covering half of the valdivia segment mw 9 1837 and iii partial ruptures of much smaller coseismic slip and extent mw 7 5 8 1737 1466 4 also distant or smaller local earthquakes can leave a specific sedimentary imprint which may resolve subtle differences in seismic intensity values for instance the 2010 event at the maule segment produced higher seismic intensities toward southeastern localities compared to previous megathrust ruptures of similar size and extent near concepci n

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

a 3400 year lacustrine paleoseismic record from the north anatolian fault turkey implications for bimodal recurrence behavior high resolution physical geochemical and geochronological analyses on the sedimentary sequence of yenicaga lake located in a fault bounded basin along the north anatolian fault reveal fingerprints of paleoearthquakes a robust sediment chronology spanning the last 3400 years is constructed by radiocarbon dating and time stratigraphical correlation with the precisely dated sofular cave speleothem record yenicaga sedimentary sequence contains 11 seismically induced event deposits characterized by siliciclastic enriched intervals some of the event deposits are also associated with implications of sudden lake deepening which may be related to coseismic subsidence the paleoearthquake series having an average recurrence interval of ca 260 years are interrupted by two possible seismic gaps of ca 420 and 540 years

istanbul s earthquake hot spots geodetic constraints on strain accumulation along faults in the marmara seismic gap during the past century a series of predominantly westward migrating m 7 earthquakes broke an 1000 km section of the north anatolian fault naf the only major remaining seismic gap along the fault is under the sea of marmara main marmara fault mmf we use 20 years of gps observations to estimate strain accumulation on fault segments in the marmara sea seismic gap we report the first direct observations of strain accumulation on the princes islands segment of the mmf constraining the slip deficit rate to 10 15 mm yr in contrast the central segment of the mmf that was thought to be the most likely location for the anticipated gap filling earthquakes shows no evidence of strain accumulation suggesting that fault motion is accommodated by fault creep we conclude that the princes islands segment is most likely to generate the next m 7 earthquake along the sea of marmara segment of the naf

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

geological and geomorphological evidence for the southwestern extension of the east anatolian fault zone turkey abstract the left lateral strike slip east anatolian fault zone eafz is the main structural link between the north anatolian fault zone nafz in north and subduction in the mediterranean sea and the transform dead sea fault zone dsfz in south we studied the southwestern continuation of the eafz using combined field investigations including geomorphology geology and paleoseismology mapping of offset drainages lineaments shutter ridges and fault planes in young geological units suggests existence of active faults between the mediterranean coast and turkoglu where it intersects with the dsfz yumurtalik and toprakkale faults are the main tectonic structures and detailed examination of geological and geomorphological evidences suggest their quaternary activity paleoseismic trenching on these faults provided evidence for at least two surface rupturing events in the last 9 000 yr detailed examination of paleo valleys of the ceyhan river suggests that the course of the river migrated due to the activity of the toprakkale fault obtained geological and geomorphological data indicates that the eafz continues across the amanos mountains and the slip transfer is mainly accommodated by the toprakkale and yumurtalik faults

the east anatolian fault geometry segmentation and jog characteristics a detailed account is given of the fault geometry and segment structure of the east anatolian fault zone as a whole based on mapping of active faults supported by available seismological and palaeoseismological data we divide the east anatolian fault into two main strands southern and northern the main southern strand is c 580 km long between karliova and antakya and connects with the dead sea fault zone and the cyprus arc via the amik triple junction the northern strand termed the surgu misis fault system is c 350 km long and connects with the kyrenia misis fault zone beneath the gulf of iskenderun we infer that slip partitioning between the main and northern strands of the east anatolian fault accommodates 2 3 and 1 3 of the slip rate of the lateral motion between the arabian and anatolian plates respectively in the celikhan adana antakya region taking account of the time elapsed from the latest events on the east anatolian fault we suggest that the pazarcik and amanos segments have the potential to produce destructive earthquakes in the near future

the seismic activity of the marmara sea region over the last 2000 years we examined the seismicity of the region of the sea of marmara in northwest turkey over the last 2000 yr using the historical record of the region we found no evidence for truly large earthquakes of a size comparable to those in the north anatolian fault zone in the marmara basin events are smaller in keeping with the known fault segmentation of the basin over the last 2000 yr seismic mo ment release accounted for the known right lateral shear velocity across the marmara region observed by global positioning system measurements its average rate is relatively constant and varies between 1 6 and 2 4 cm yr the long term seismicity in the marmara sea region shows that large earthquakes are less frequent than pre dicted from the 100 yr long instrumental period

block like plate movements in eastern anatolia observed by insar 1 the question whether continental plates deform internally or move as rigid blocks has been debated for several decades to further address this question we use large scale interferometric synthetic aperture radar insar data sets to study how eastern anatolia and its surrounding plates deform we find that most of the deformation is focused at the north and east anatolian faults and little intraplate deformation takes place anatolia is therefore moving at least its eastern part as a uniform block we estimate the slip velocity and locking depth of the north anatolian fault at this location to be 20 mm yr and 14 km respectively high deformation gradient found near the east anatolian fault on the other hand suggests that little stress is accumulating along the eastern sections of that fault

sand composition changes across key boundaries of siliciclastic and hybrid depositional sequences abstract sand composition of arenite successions is sensitive to a suite of factors operating between initial grain production and final diagenesis on a variety of spatial and temporal scales seven allogenic factors the relative importance of which relies upon the complex interaction between tectonics eustasy and climate play a decisive role in dictating petrofacies distribution within siliciclastic to hybrid depositional sequences these factors include i tectonic exhumation ii physical and chemical rock breakdown iii change in sediment flux iv change in source basin physiography v shelf colonization by organisms vi generation of chemical grains and vii volcanism autogenic processes may locally have a considerable influence on the type and amount of sediment supplied to the basin thus interfering with the external control based upon literature data a conceptual framework of expected compositional changes across the key surfaces for sequence stratigraphic interpretation is outlined two case histories from the miocene shelf to turbidite deposits of the northern apennines and the quaternary alluvial to nearshore succession of the adriatic coast respectively are used as references to illustrate how arenite petrofacies changes can be framed into a sequence stratigraphic scheme on multiple timescales

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

late pleistocene holocene sedimentary records of climate and lake level changes in lake hazar eastern anatolia turkey abstract the sedimentary record of lake hazar has been documented by detailed seismo and chronostratigraphic analyses using high resolution seismic profiles and sediment cores in this study two main seismic stratigraphic units can be confidently correlated with sediment cores using lithology and physical properties as a result of radiocarbon ams dating these sedimentary units presumably cover the period from the late pleistocene to holocene the holocene sequence of the lake infills can be subdivided into five subunits each subject to distinctive hydrological and sedimentological processes due to fluctuating lake level the elevations of these deposits including coastal paleo terraces provide history of the lake level changes in lake hazar the maximum lowstand lake level occurred during the transition from the younger dryas to holocene when the 73 m wave cut terrace was formed as the main shelf crossing unconformity surface the beginning of the holocene was associated with a abrupt lake level rise and resultant deepening analysis of the lake hazar terraces has the potential to provide complementary data on the chronology of past lake level and lake volume changes and their link to past climate change the continued rising lake level during beginning of the holocene was modulated by stillstands at 63 m and 56 m as indicated by broad coastal paleo terraces across the northern shelf the main shelf margin sedimentary system for the holocene period is composed of three distinct buried deltaic complexes that were presumably sourced from the kurkcayi river the largest input into lake hazar the 3rd millennium crisis at around 3 14c ka bp is recorded in the seismic and core data when the cold and dry climatic condition gave rise to a significant lake level drop

age and geotectonic setting of late neoproterozoic juvenile mafic gneisses and associated paragneisses from the ribeira belt se brazil based on geochemistry and sm nd data implications on gondwana assembly abstract mafic gneisses and associated paragneisses from the cabo frio tectonic domain in the southeastern part of the ribeira belt along the coast of rio de janeiro state in southeast brazil were subjected to a geochemical and sm nd isotope study four lithotypes are distinguished aluminous paragneisses mainly sillimanite kyanite garnet biotite gneiss calcsilicate lenses quartzo feldspathic metasedimentary gneisses and mafic ultramafic lenses the whole rock major and trace including rare earth element distributions in the mafic ultramafic intercalations indicate that derivation from subalkaline basalt gabbro of tholeiitic affinity with e morb signature from a non subduction environment these mafic rocks have positive end t and tdm of 1 1 ga the metasedimentary rocks have negative end t and tdm of 1 7 ga a sm nd whole rock isochron of mafic rocks yielded an age of 604 38 ma for the crystallization this matches with the age of some detrital zircon grains from the paragneisses the depositional basin named buzios palmital was active at least until 620 ma age of the youngest detrital zircon and was subsequently deformed and metamorphosed at ca 525 ma age of metamorphic zircons during the buzios orogeny it is interpreted as a back arc basin with relation to the 630 ma magmatic arc of the oriental terrane in the ribeira belt to the nw however after 600 ma the buzios palmital basin changed to an active margin setting because the arc collided with the continental margin and the subduction shifted to the back arc environment by 610 ma most of the brasiliano belts registered collisional events related to multiple convergent blocks the stress fields and paleocontinent shapes would have allowed the occurrence of extensional areas with not only sedimentary deposition but also ocean floor spreading its remnants are preserved in this brazilian coastal region as an ancient suture reworked intensively during the mesozoic rifting events the reconnaissance of late neoproterozoic basins in the brasiliano pan african belts is of major importance to partially unravel the final amalgamation events of sw gondwana considering that the buzios palmital basin rock units are mostly covered by the marginal atlantic basins it is possible that other evidence could be preserved in the coastal regions of sw africa and se south america

time dependent recurrence of strong earthquake shaking near plate boundaries a lake sediment perspective abstract accurate probabilistic seismic hazard analysis requires a good knowledge of the recurrence parameters of the strongest earthquakes in a region due to the typical short temporal span of instrumental and historical data it is often unclear whether one should adopt a time dependent or time independent poissonian recurrence model the choice of which has large repercussions on the probability estimates for new strong events the rapidly growing discipline of lacustrine paleoseismology aims at producing long continuous records of strong seismic shaking which integrate the activity of all significant seismic sources in a region and allow a reliable determination of recurrence patterns the typical continuous sedimentation regime in lakes can lead to complete sensitive paleoseismic records and a reduced temporal uncertainty in recurrence intervals here i present a worldwide compilation of published long lacustrine paleoseismic records grouped per tectonic domain and statistically explore the variability of their recurrence intervals expressed by the coefficient of variation cov a cov 1 indicates a time independent process whereas cov 1 may be related to changes in the sensitivity of the lacustrine paleoseismograph or to real earthquake clustering due to e g stress transfer between neighboring faults the most useful lacustrine paleoseismic records can be retrieved in high seismicity settings where many paleoseismic events can be recorded in a relatively short time span i e

juvenile accretion at 750 700 ma in southern brazil a revista economic geology nao autoriza a publicacao de seus artigos em repositorios institucionais

the velocity field along the san andreas fault in central and southern california the velocity field within a 100 km broad zone centered on the san andreas fault between the mexican border and san francisco bay has been inferred from repeated surveys of trilateration networks in the 1973 1989 interval the velocity field has the appearance of a shear flow that remains parallel to the local strike of the fault even through such major deflections as the big bend of the san andreas fault in the transverse ranges of southern california across strike profiles of the fault parallel component of velocity exhibit the expected sigmoidal shape whereas across strike profiles of the fault normal component of velocity are flat and featureless no significant convergence upon the fault is observed even along the big bend sector of the fault simple dislocation models can explain most of the features of the observed velocity field but those explanations are not unique about 35 mm yr of relative plate motion is accounted for within the span of the trilateration networks geologic studies indicate that the secular slip rate on the san andreas fault is about 35 mm yr the agreement between these two estimates implies that most of the strain accumulation is elastic and will be recovered in subsequent earthquakes the relative motion observed across the san andreas fault 35 mm yr plus that observed across the eastern california shear zone 8 mm yr accounts for most 43 mm yr of the observed north america pacific relative plate motion 47 mm yr

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research