lithospheric structure in central eurasia derived from elevation geoid anomaly and thermal analysis we present new crustal and lithospheric thickness maps for central eurasia from the combination of elevation and geoid anomaly data and thermal analysis the results are strongly constrained by numerous previous data based on seismological and seismic experiments tomographic imaging and integrated geophysical studies our results indicate that high topography regions are associated with crustal thickening that is at a maximum below the zagros himalaya tien shan and the tibetan plateau the stiffer continental blocks that remain undeformed within the continental collision areas are characterized by a slightly thickened crust and flat topography lithospheric thickness and crustal thickness show different patterns that highlight an important strain partitioning within the lithosphere the arabia eurasia collision zone is characterized by a thick lithosphere underneath the zagros belt whereas a thin to non existent lithospheric mantle is observed beneath the iranian and anatolian plateaus conversely the india eurasia collision zone is characterized by a very thick lithosphere below its southern part as a consequence of the underplating of the cold and stiff indian lithosphere our new model presents great improvements compared to previous global models available for the region and allows us to discuss major aspects related to the lithospheric structure and acting geodynamic processes in central eurasia

large volume lava flows fed by a deep magmatic reservoir at agri dagi ararat volcano eastern turkey agri dagi ararat whilst being the tallest volcano in turkey is largely understudied two predominant peaks greater and lesser agri make up the main edifice which has been built during four main phases the most recent phase consisted of two volcanic eruptions the respective surface area and volume of the first volcanic eruption were estimated at 96 km2 and 3 2 km3 whereas those of the second eruption were much smaller with the surface area and volume estimated at 25 km2 and 0 6 km3 it is unusual for stratovolcanoes to produce basaltic eruptions of more than 3 km3 although these and larger volumes are not uncommon in flood basalt type eruptions large basaltic eruptions from stratovolcanoes normally require volcano tectonic forcing e g subsidence of collapse caldera and graben however there is no evidence for such volcano tectonic forcing during the most recent eruptions at agri dagi ararat and therefore their comparatively large volume basaltic lavas need to be explained in a different way here we present an analytical method for calculating the source volume needed to supply magma to the eruptions at agri dagi we found that the lava flow of 3 2 km3 was likely fed by a very large magma reservoir 13 000 km3 while the second flow of 0 6 km3 was fed by a reservoir of a much smaller effective size or 2000 km3 effective size depends on what fraction of the reservoir participates in the eruption we propose that the entire reservoir supplied magma to the larger eruption but only one of its compartments about one fifth of the total volume of the reservoir supplied magma to the smaller eruption although seismic tomography indicates a magma reservoir at great depths 20 30 km below the agri dagi volcano geochemical constraints on some of the later formed rocks suggest an interaction between a shallow chamber at 8 10 km depth and the deep reservoir approximately 0 5 ma we provide numerical models whose results indicate that dykes injected from the lateral margins of the deep seated reservoir are more likely to reach the surface directly rather than replenish the shallow magma chamber suggesting also that the compartment for the second eruption was at the margin of the reservoir

dipping structure under dourbes belgium determined by receiver function modeling and inversion abstract teleseismic broadband p and s waves recorded at the nars station ne06 dourbes belgium are shown to exhibit strong anomalous particle motion not attributable to instrument miscalibration or malfunction azimuthally varying radial and tangential components have been observed on 38 recordings after vector rotation of horizontal p waves into the ray direction the tangenital p waves attain amplitudes comparable to the radial components from the east with negative polarity and west with positive polarity but tend to be zero in the north and south suggesting major discontinuities in the crust dipping southward the sh wave from the east contains a large spmp phase an s to p conversion at the free surface and then reflected back to the surface from the moho the polarity of this spmp phase presents further evidence for a southward dipping moho we employ ray theory for three dimensionally dipping interfaces to compute the p wave response linear inverse theory with smoothness constraints is applied to the simultaneous inversions of p wave receiver functions for four different backazimuths through the progressive change of interface strike and dip and the inversion of layer shear wave velocities a dipping crustal model that is consistent with both the observed waveforms and results of previous local geophysical surveys has been determined the results suggest a large velocity contrast in the shallow structure near the surface another major interface at a depth of 12 km with dip of 10 and a seismically transparent unit below the interface the interface at a depth of 12 km reportedly emerges at the midi fault 50 km north of the station ne06

crustal structure of the adirondacks determined from broadband teleseismic waveform modeling broadband receiver functions developed from teleseismic p waveforms recorded on the midperiod passband of the department of energy s regional seismic test network station rsny are analyzed to examine the crustal structure beneath the adirondack highlands of upstate new york radial receiver functions are inverted in the time domain to determine the vertical shear velocity structure at four distinct back azimuths lateral changes in structure are identified by examining azimuthal variations in the vertical structure southeast of rsny our model consists of a thick crust including a broad crust mantle transition the most prominent structure is a high velocity zone shear velocity 4 0 km s between 18 and 26 km depth which overlies a lower crust of low average shear velocity 3 7 km s the extent of the high velocity zone correlates in depth with a highly reflective zone in consortium for continental reflection profiling profiles se of rsny while the deep low velocity zone may be correlated with a broad electrical conductivity anomaly in the adirondacks this general structure is also seen sw of rsny but is more difficult to document at nw and ne azimuths

seismic velocity and poisson s ratio tomography of the crust beneath east anatolia abstract eastern anatolia is a region in the early stages of continent continent collision and so provides a unique opportunity to study the early development of continental plateau located within the alpine himalayan fold thrust fault belt the anatolian plateau is geologically very complex with over half of the surface area covered with late cenozoic volcanics of diverse composition the plateau is also seismically active and is dissected by numerous seismogenic faults predominantly of strike slip motion in this study we determine 3 d tomographic images of the crust beneath eastern anatolia by inverting a large number of arrival time data of p and s waves from the obtained p and s wave velocity models we estimated the poisson s ratio structures for a more reliable interpretation of the obtained velocity anomalies our tomographic results are generally consistent with the major tectonic features of the region high p and s wave velocity anomalies are recognized near the surface while at deeper crustal layers low seismic wave velocities are widely distributed poisson s ratio exhibits significant structural heterogeneities compared to the imaged velocity structure the seismic activity is intense along highly heterogeneous zones and is closely associated with pre existing faults in the central and western parts of the study area results of the checkerboard resolution test indicate that the imaged anomalies are reliable features down to a depth of about 40 km the low velocity high poisson s ratio zones in the middle to lower crust are consistent with many geophysical observations such as strong sn attenuation low pn and sn velocity and the absence of mantle lid implying the presence of partial melt in the uppermost mantle

shear wave velocity structure in the northern basin and range province from the combined analysis of receiver functions and surface waves a new method based on the joint inversion of receiver functions and surface wave phase velocities results in well determined shear velocity structures that are consistent with the compressional wave structure gravity heat flow and elevation data in the northern basin and range this new inversion method takes advantage of average velocity information present in the surface wave method and differential velocity information contained in the receiver function method thus min imizing the nonuniqueness problem that results from the velocity depth trade off an unusually thick 38 kin and relatively faster crust and upper mantle are found in central and eastern nevada compared to the thin 28 to 34 km and slower crust and upper mantle of the western basin and range we interpret the regions of thicker and faster crust and upper mantle as zones that have undergone less cenozoic ex tension relative to the surrounding regions to the west and north the thick crust and consequently greater depth to the dense mantle material is consistent with the gravity low pattern in central and eastern nevada simple gravity modeling shows both local and regional isostatic compensation occur within 40 km of the surface indicating a near classical airy type of compensation in the province we analyze in detail the shear wave s wave velocity model derived from the receiver functions at station bmn and compressional wave p wave velocity models derived from the 1986 passcal experiment in northwestern nevada the most interesting feature of these models is the presence of negative velocity gradients in the s wave model with no corresponding velocity decrease in the p wave models between depths of 10 and 24 km this combined velocity model may be explained by high pore fluid pressures at these depths this model favors a layered fluid porosity model proposed in the literature to explain extensive middle to lower crust conti nental seismic reflections and high electrical conductivity an upper mantle grada tional low velocity zone is present between 32 and 38 km in the s wave model this upper mantle shear wave low velocity zone is consistent with partial melt which may be the source material for magmatic underplating in this region

forward modelling receiver functions for crustal structure beneath station tbz trabzon turkey we use teleseismic three component digital data from the trabzon turkey broadband seismic station tbz to model the crustal structure by the receiver function method the station is located at a structural transition from continental northeastern anatolia to the oceanic black sea basin rocks in the region are of volcanic origin covered by young sediments by forward modelling the radial receiver functions we construct 1 d crustal shear velocity models that include a lower crustal low velocity zone indicating a partial melt mechanism which may be the source of surfacing magmatic rocks and regional volcanism within the top 5 km velocities increase sharply from about 1 5 to 3 5 km s 1 such near surface low velocities are caused by sedimentation extending from the black sea basin velocities at around 20 km depth have mantle like values about 4 25 km s 1 which easily correlate to magmatic rocks cropping out on the surface at 25 km depth there is a thin low velocity layer of about 4 0 km s 1 the average moho velocity is about 4 6 km s 1 and its depth changes from 32 to 40 km arrivals on the tangential components indicate that the moho discontinuity dips approximately southwards in agreement with the crustal thickening to the south we searched for the solution of receiver functions around the regional surface wave group velocity inversion results which helped alleviate the multiple solution problem frequently encountered in receiver function modelling station tbz is a recently deployed broadband seismic station and the aim of this study is to report on the analysis of new receiver function data the analysis of new data in such a structurally complex region provides constraining starting models for future structural studies in the region

propagation characteristics of short period sn and lg in the middle east abstract we present propagation characteristics of the short period regional seismic phases sn and lg for the middle east digital waveform data from the iranian long period array ilpa and the global seismic network gsn stations abkt alibek turkmenistan anto ankara turkey keg kottamya egypt and kiv kislovodsk georgia were used in this study three component rotated seismograms were bandpass filtered 0 5 to 5 0 hz and examined for the presence and strength amplitude of sn and lg relative to the pn and pg phases the short period sn and lg waveforms show great variability sn propagates efficiently for paths crossing the mediterranean black and caspian seas as well as for paths passing north of the greater caucasus alborz and kopet dag mountains generally sn is not observed or propagates inefficiently for paths with segments beneath the turkish plateau and northern iranian plateau consistent with a previous study by kadinsky cade et al 1981 this study finds that the zone of inefficient sn propagation coincides with a zone of low pn velocities pn tomography lg is consistently not observed for paths crossing the mediterranean black and caspian seas lg propagates efficiently for paths crossing the northern arabian shield generally lg propagates efficiently for paths contained within the turkish iranian plateau paths in the middle east greater than about 2000 km consistently show no or little lg energy the correspondence of zones of inefficient sn propagation and low pn velocities suggests that high temperatures and partial melt lie at shallow depths in the upper mantle beneath the turkish plateau and northern iranian plateau the presence of water presumably due to subduction of hydrated oceanic crust lowers the solidus temperature and enhances partial melt lg is blocked by oceanic crustal structures as well as by structural and topographic variations associated with tectonic boundaries

multistep modelling of teleseismic receiver functions combined with constraints from seismic tomography crustal structure beneath southeast china summary with a growing number of modern broad band seismographic stations in asia the conditions have improved to allow higher resolution structural studies on regional scales here we perform a receiver based study of the lithosphere of southeast china using waveform records ofexcellentqualityfrom14chinesenationaldigitalseismicnetworkandfourglobalseismic network stations calculating the theoretical receiver functions rfs that match the observed rfs from teleseismic waveforms is an established technique for retrieving information about crustalanduppermantlestructurebeneathaseismicreceiver rfs however arepredominantly sensitivetothegradientsinthelithosphericelasticparameters anditisimpossibletodetermine a non unique distribution of seismic parameters such as absolute shear wave speeds as a function of depth unless other geophysical data are combined with rfs thus we combine rfswithindependentinformationfromshearandcompressionalwavespeedsaboveandbelow the mohoroviy discontinuity available from the existing tomographic studies we introduce a statistical approach for automatically selecting only mutually coherent rfs from a large set of observed waveforms furthermore an interactive forward modelling software is introduced and applied to observed rfs to define a prior physically acceptable range of elastic parameters in the lithosphere this is followed by a grid search for a simple crustal structure an initial model for a linearized iterative inversion is constructed from multiple constraints including results from the grid search for shear wave speed the moho depth versus vp vs ratio domain search and tomography the thickness of the crust constrained by our multistep approach appears to be more variable in comparison with tomographic studies with the crust thinning significantly towards the east we observe low values of vp vs ratios across the entire region which indicates the presence of a very silicic crust we do not observe any correlation between the crustal thickness or age of the crust with vp vs ratios which argues against a notion that there is a simple relationship between mineralogical composition and crustal thickness and age on a global scale

lateral variation in crustal structure of the northern tibetan plateau inferred from teleseismic receiver functions we investigate lateral variations in crustal structure across the northern boundary of the tibetan plateau using the receiver functions at three broadband stations deployed during the 1991 1992 tibet passcal experiment the first 5 sec of the receiver functions vary systematically with backazimuth the radial receiver functions are symmetric across the n s axis while the tangential receiver functions are antisymmetric across this axis this symmetry can be modeled by e w striking dipping interfaces in the upper middle crust the strike direction is consistent with the e w trend of surface geology modeling a p to s converted phase in the receiver functions at each station suggests that there is a mid crustal low velocity layer with its upper boundary dipping 20 to 30 to the south in addition a shallow northward dipping interface is responsible for the double peaked direct p arrivals in the radial receiver functions and large tangential motions at one of the stations the low velocity layer together with other geological and seismological observations suggests that there is a hot possibly partial melt zone in the middle crust of northern tibet alternately dipping velocity interfaces might be associated with some buried thrust faults in the upper crust that accommodated crust shortening during the plateau formation

the structure of the core mantle boundary from diffracted waves diffracted p and s waves pd sd traveling around the core mantle boundary cmb of the earth give us information about the velocity structure and therefore the thermochemistry of d the base of the earth s mantle by examining pd and sdarrivals we determined the apparent ray parameter for different regions at the base of the mantle by comparing the data slownesses to those found from reflectivity synthetic seismograms we were able to quantify d average velocities using these averaged velocities with a thermochemical modeling of lower mantle minerals using a birch mumaghan equation of state we have been able to make chemical and physical inferences as to the causes of lateral variations at the cmb examinations found significant lateral heterogeneity at the base of the mantle amounting to 4 for both p and s velocities these velocities did not always vary in parallel and the poisson ratio varied regionally by almost 6 the most unusual region of the cmb found was under indonesia where velocities 3 slower than the preliminary reference earth models were found adjacent to a region of faster than average velocities these regions currently correspond to areas of core up welling and down welling respectively found by voorhies 1986 which if mostly held in place by core mantle coupling might cause a flux of heat and iron into the mantle making the anomaly both thermally and chemically derived at the cmb under the northern pacific rim the fastest shear velocities were found but the same region yielded slower than average p velocities while the presence of fast shear velocities here would support the idea that we are seeing the cold dregs of mantle convection perhaps continuing down from the north pacific subduction zones the presence of slow p velocities suggests additional complications our thermochemical modeling suggests that the d poisson ratio is very sensitive to variations in the silicate oxide ratio and that a decrease in the amount of perovskite relative to magnesiowustite may play an important role in this region

a study on the active crustal deformation of the north and east anatolian fault zones abstract active crustal deformation in the north anatolian fault zone nafz and the east anatolian fault zone eafz based on seismicity data is examined the results show that the deformation in the nafz is taken up by extension on an azimuth of 59 at a rate of 27 mm yr and as compression on an azimuth of 149 and a rate of 20 mm yr the average dextral lateral motion on the naf is about 23 mm yr this motion in the western part of the naf is 16 mm yr while it increases in the eastern part of the fault to 27 mm yr in the eafz the deformation is taken up as nearly n s compression n7 e at a rate of 5 mm yr and as nearly e w extension n97 at a rate of about 9 mm yr the average sinistral lateral motion has a rate of about 6 mm yr the expected slip rates from plate motions along the north anatolian fault are of the order of 38 mm yr the predicted slip rates for east anatolian fault are 19 mm yr or 29 mm yr the seismicity of the last 140 years can account for the expected deformation along the nafz for the eafz however it is possible that part of the total deformation has been expressed aseismically

azimuthal shear wave velocity anisotropy in the basin and range province using moho ps converted phases an eight station large aperture seismometer array was deployed in the basin and range province of west central nevada for the 1988 1989 program for array seismic studies of the continental lithosphere passcal passive source seismic experiment during the 10 months of data collection a total of 100 teleseismic events were recorded 30 source equalized p wave receiver functions show waveform variations in timing amplitude and polarity in the moho ps phase that is diagnostic of shear wave velocity anisotropy information regarding the crustal anisotropic component can be recovered through the ps phase since it is generated at the moho and is sensitive to shear wave splitting in the crust only we utilize single event stacked and array beam formed receiver functions to minimize the influence of structural variations and scattering on the observed converted phases analysis of shear wave splitting of the ps conversion from the crust mantle boundary indicates a fast azimuth of anisotropy oriented approximately nw se with observed time delays of 0 20 s this strongly suggests coherent crustal anisotropy with a fast direction perpendicular to the strike of fault block mountain ranges this fabric is most likely due to the preferred crystallographic orientation of seismically anisotropic minerals in the middle to lower crust rather than the distribution of basin and range upper crustal fracture systems

coastal katabatic winds imaged by sar 1 sea surface imprints of coastal katabatic winds are observed on a radarsat 1 synthetic aperture radar sar standard mode image off the u s west coast taken on january 21 2003 the katabatic wind pattern is shown in the sar image as a striking finger like bright dark region that mirrors the coastal mountain topography we simulate the low level atmospheric circulation using the numerical weather model mm5 with a triply nested grid technique the model simulation reproduces the finger like katabatic wind pattern at the sar imaging time katabatic wind is strongest in the morning when the surface temperature gradient between ocean and land reaches a maximum the sea surface wind simulated by the mm5 model and that derived from the calibrated sar normalized radar cross section are in good agreement the katabatic wind variation along the coastline is between 5 8 ms 1 and the longest wind finger stretches over 20 km offshore

the receiver structure beneath mina nevada abstract receiver functions obtained from broadband teleseismic p waveforms recorded at seismic station mnv near mina nevada are inverted for the vertical shear wave velocity structure southeast of the station the time domain inversion procedure for vertically heterogeneous and laterally homogeneous one dimensional models includes smoothness constraints to minimize model roughness and a pseudo monte carlo approach to investigate the nonuniqueness of the solution models we also report on the potential effects of scattering on a receiver function inversion for a one dimensional velocity structure mnv receiver functions sample the walker belt crust and upper mantle beneath the soda spring valley and pilot mountains to the east and the garfield hills and excelsior mountains to the west of the station the preferred southeast solution models show a smooth positive gradient in the mid and lower crust with the top of the crust mantle boundary at 34 to 36 km depth reaching an upper mantle p velocity of 7 8 to 7 9 km sec 1 between 38 and 40 km these results suggest that the crust beneath mnv may be representative of a transition zone between typical basin and range province crust to the east and a thicker sierran block to the west of the station

seismic velocity and q structure of the middle eastern crust and upper mantle from surface wave dispersion and attenuation observed velocities and attenuation of fundamental mode rayleigh waves in the period range 7 82 sec were inverted for shear wave velocity and shear wave q structure in the middle east using a two station method additional information on q structure variation within each region was obtained by studying amplitude spectra of fundamental mode and higher mode rayleigh waves we obtained models for the turkish and iranian plateaus region 1 areas surrounding and including the black and caspian seas region 2 and the arabian peninsula region 3 the effect of continent ocean boundaries and mixed paths in region 2 may lead to unrealistic features in the models obtained there at lower crustal and upper mantle depths shear velocities are similar in all three regions shear velocities vary significantly in the uppermost 10 km of the crust being 3 21 2 85 and 3 39 km s for regions 1 2 and 3 respectively q models obtained from an inversion of interstation attenuation data show that crustal shear wave q is highest in region 3 and lowest in region 1 q s for the upper 10 km of the crust are 63 71 and 201 for regions 1 2 and 3 respectively crustal q s at 30 km depth for the three regions are about 51 71 and 134 the lower crustal q values contrast sharply with results from stable continental regions where shear wave q may reach one thousand or more these low values may indicate that fluids reside in faults cracks and permeable rock at lower crustal as well as upper crustal depths due to convergence and intense deformation at all depths in the middle eastern crust

receiver structure beneath the southern mojave block california an inversion of a receiver function recorded at lawrence livermore national laboratory nevada test site network station lac reveals a range of 1 d velocity structures that are consistent the observed waveform the shear velocity structure southeast of lac is relatively simple consisting of an approximately 30 to 34 km thick crust all models contain relatively sharp crust mantle boundaries with a change in velocity from about 3 5 km sec to approximately 4 6 km sec over a depth range of 4 to 6 kilometers the range of models can be roughly divided into two groups that differ mostly in the mid to lower crust the first model of the earth structure contains a large low velocity zone in the middle and lower crust shear wave velocities as low as 2 8 km sec the second model contains nearly constant velocities approximately 3 5 km sec through the middle to lower crust in contrast with the simplicity of the southeast receiver function the receiver functions corresponding to the northwest and southwest show the influence of lateral velocity heterogeneity and can at best be discussed qualitatively

crustal thickness of turkey determined by receiver function abstract two hundred and sixty seven teleseismic events with a moment magnitude greater than 5 5 which occurred between january 2005 and october 2010 were analyzed to determine the moho depth variation beneath turkey by using the receiver function rf technique the rf technique was applied to 120 broadband seismic stations which were already deployed in the area permanently by the kandilli observatory and earthquake research institute koeri and the disaster and emergency management presidency afad the rfs were stacked considering back azimuth slowness and waveform similarities to enhance the signal noise ratio the genetic algorithm ga was used to obtain both 1 d shear wave speed model and the moho depth beneath each seismic station a data set consisting of 112 shear speed models derived from rfs revealed the crustal structure of turkey for imaging several 2 d profiles of depth migrated rfs were constructed to delineate the fine crustal structure the moho discontinuity is clearly seen on all profiles and the mid crustal velocity discontinuity within the crust is observed in some profiles the depth of the moho varies between 24 and 48 km the thinnest crustal thickness is located on the coast of western turkey and the deepest moho boundary is observed in eastern turkey the shear wave velocities vary between 4 0 km s and 4 5 km s in the uppermost mantle beneath turkey

constraints on crustal structure and complex moho topography beneath pinon flat california from teleseismic receiver functions abstract we use teleseismic p waves recorded at pinon flat observatory pfo to constrain the three dimensional crustal and upper mantle velocity structure beneath the station by forward modeling radial receiver function waveforms we construct a one dimensional crustal model that includes a significant shear velocity inversion at 9 km in depth arrivals on the tangential components indicate dip of at least the uppermost discontinuity complicated moho topography deepening to the northwest of pfo is suggested by azimuthal dependence of travel times and amplitudes of the receiver functions and travel times of crustal p wave reverberations although fine details cannot be resolved each of those sets of observations plus mislocation vectors provide strong indications of abrupt moho topography possibly including step offsets of several kilometers this is not only consistent with gravity data in implying airy isostasy with compensation at moho depth but extends that model to a much finer length scale than had been resolved

seismic evidence for an ancient rift beneath the cumberland plateau tennessee a detailed analysis of broadband teleseismic p waveforms broadband receiver functions developed from teleseismic p waveforms recorded on the midperiod passband of regional seismic test network station rscp are inverted for vertical velocity structure beneath the cumberland plateau tennessee the detailed broadband receiver functions are obtained by stacking source equalizd horizontal components of teleseismic p waveforms the resulting receiver functions are most sensitive to the shear velocity structure near the station a time domain inversion routine utilizes the radial receiver function to determine this structure assuming a crustal model parameterized by many thin flat lying homogeneous layers lateral changes in structure are identified by examining azimuthal variations in the vertical structure the results reveal significant rapid lateral changes in the midcrustal structure beneath the station that are interpreted in relation to the origin of the east continent gravity high located northeast of rscp the results from events arriving from the northeast show a high velocity midcrustal layer not present in results from the southeast azimuth this velocity structure can be shown to support the idea that this feature is part of a keweenawan rift system another interesting feature of the derived velocity models is the indication that the crust mantle boundary beneath the cumberland plateau is a thick probably laminated transition zonemore between the depths of 40 and 55 km a result consistent with interpretations of early refraction work in the area less

source parameters of large earthquakes in the east anatolian fault zone turkey summary the east anatolian fault zone accommodates most of the motion between the arabian plate and the apparently little deforming interior of central turkey the direction of overall slip across this zone is crucial to the determination of the slip rate on the north anatolian fault we use long period p and sn waveforms to determine the source parameters of the four largest earthquakes that occurred in or near the east anatolian fault zone in the last 35 years only one of these actually involved left lateral strike slip motion on a ne sw fault but the other three and the nearby 1975 lice earthquake all had steeply dipping nodal planes with a nnw strike if these were the auxiliary planes then all the earthquakes had a slip vector direction within about 10 of 063 if this direction represents the arabia turkey motion then the slip rate on the north anatolian fault must be in the range 31 to 48 mm yr with a probable value of 38 mm yr and the overall slip rate across the east anatolian fault zone must be about 29mmyr with a range of 25

analyses of a 426 day record of seafloor gravity and pressure time series in the north sea continuous gravity observations of ocean and solid tides are usually done with land based gravimeters in this study we analyze a 426 day record of time varying gravity acquired by an ocean bottom scintrex spring gravimeter between august 2005 and november 2006 at the troll a site located in the north sea at a depth of 303 m sea bottom pressure changes were also recorded in parallel with a paroscientific quartz pressure sensor from these data we show a comparison of the noise level of the seafloor gravimeter with respect to two standard land based relative gravimeters a scintrex cg5 and a gwr superconducting gravimeter that were recording at the j9 gravimetric observatory of strasbourg france we also compare the analyzed gravity records with the predicted solid and oceanic tides the oceanic tides recorded by the seafloor barometer are also analyzed and compared to the predicted ones using fes2014b ocean model observed diurnal and semi diurnal components are in good agreement with fes2014b predictions smallest constituents reflect some differences that may be attributed to non linearity occurring at the troll a site using the barotropic tugo m dynamic model of sea level response to ecmwf atmospheric pressure and winds forcing we show a good agreement with the detided ocean bottom pressure residuals about 4 hpa of standard deviation of remaining sea bottom pressure are however not explained by the tugo m dynamic model

strike slip fault geometry in turkey and its influence on earthquake activity the geometry of turkish strike slip faults has been reviewed and described from this data set it appears that fault geometry the distribution of discontinuities such as bends and stepovers along the main fault trace plays an important role in controlling the location of large earthquake rupture segments along the fault zones large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30 more important than the size of each discontinuity however is the total geometric pattern i e the distribution of adjacent bends and stepovers based not only on distance from one another but also on relative discontinuity size certain geometric patterns restraining single or double bends are particularly common and can be viewed as responsible for strain accumulation along portions of the fault zone fault geometry not only plays a role in the extent of earthquake rupture but also in characteristics of earthquake behavior for example large earthquake epicenters often occur near restraining bends or double bends furthermore aftershocks and swarm activity can often be associated with releasing areas areas along the strike slip fault that are undergoing a relatively large amount of extension

on the structure of the crust and upper mantle beneath the afro arabian region from surface wave dispersion abstract the deep structure beneath the afro arabian region was investigated using rayleigh and love waves in the period range 20 250 s models of crustal and upper mantle structure were inferred by simultaneous inversion of both phase and group velocities our choice of model parametrization allowed for a transverse isotropic medium and a variable depth of the moho the crustal thicknesses were found to vary from 43 to 45 km on the african plate the moho is deeper in the arabian plate 45 47 km but in the vicinity of the red sea the crust becomes much thinner 30 km the upper mantle under arabia is more similar to that of an african mobile zone than to that of a shield a low velocity zone lvz with an s wave velocity of 4 14 4 2 km s was found in the depth range 120 140 km however this lvz is less pronounced than that found in the vicinity of the red sea s wave velocity 4 08 km s in agreement with previous studies the anisotropy v sh v sv v sv has been verified for the afro arabian region we interpret the anisotropies uisng the hypothesis of lattice preferred orientation of the olivine crystals in the upper mantle the inference is that a vertical flow exists up to near the surface in the vicinity of the red sea rift vsv is 8 9 faster than vsh under the african and arabian sides the flow is essentially vertical below depths of 200 40 km and becomes essentially horizontal above with a vsh from 6 to 14 faster than vsv

crustal structure and possible anisotropy in turkey from seismic surface wave dispersion summary the velocity structure of two regions of turkey are determined using single station measurements of rayleigh and love wave group velocities in the period range 8 50s a differential inversion scheme yields models for turkey in which crustal and upper mantle shear wave velocities are slower than those of most of europe comparisons of upper mantle shear wave velocities we have obtained with reported p velocities leads to poisson s ratio values in the upper mantle between 0 29 and 0 30 for eastern turkey and between 0 27 and 0 31 for western turkey crustal velocities are slightly slower and upper mantle velocities are slightly faster in western turkey than in eastern turkey the crust mantle boundary obtained in our studies is gradational but if a shear velocity of 4 2 km s l is taken to define the upper mantle then the crust appears to be about 40 km thick throughout all of turkey a sharp crust mantle boundary may occur but cannot be resolved the data of this study require neither a low velocity zone in the upper mantle nor polarization anisotropy in the crust or upper mantle azimuthal variations of rayleigh and love wave group velocities in western turkey are consistent with velocities predicted by an azimuthally anisotropic upper crust in which vertical cracks are orientated in an approximate e w direction this interpretation is consistent with geological information fault plane solutions lineations mapped from satellite observations and reported heat flow values but the possibility that these variations are caused by lateral changes of velocity in the crust of western turkey cannot be completely ruled out at the present time

lateral variations of high frequency seismic wave propagation at regional distances across the turkish and iranian plateaus in this study we investigate crustal and uppermost mantle physical properties that characterize some of the continental plateaus of the middle east this is done as part of a larger effort to map and compare high frequency wave propagation at regional distances across the earth s continental plateaus thousands of short period wwssn seismograms recorded at stations located in the middle east and produced by earthquakes with epicentral distances less than about 20 were examined visually in an effort to study lateral variations of high frequency 0 5 2 hz seismic wave propagation across this area particularly to the north of the zone of continental collision between the africa arabian and eurasian plates variations of frequencies and amplitudes of sn and lg relative to p are examined and mapped throughout the region and this work is supplemented by a study of velocities of pn sn and lg sn amplitude variations are very striking in this area an important observation of this study is that sn propagates efficiently beneath a major part of the turkish and iranian plateaus sn is strongly attenuated however in the northernmost portion of the plateaus south of the black and caspian seas and in an area between the two seas these regions are characterized in general by active tectonism including volcanism faulting and folding however this active tectonism is not restricted to the areas of high sn attenuation but appears to extend beneath other parts of the iranian and turkish plateaus patterns of lateral variations in the propagation of lg are not as consistent as those for sn lg propagates efficiently across turkey iran and adjacent regions but the lg waves that cross the turkish and iranian plateaus are weak and have relatively long predominant periods of about 2 5 s the lg phase is not observed when the path of propagation crosses the southern caspian and the black seas consistent with the evidence of oceanic type crustal structure beneath these seas lg is also not observed from subcrustal events located in the hindu kush region the velocity of pn beneath most of the plateau areas and particularly in the regions of sn attenuation ranges between 8 0 and 8 2 km s velocities for sn and lg throughout the middle east are about 4 5 and 3 4 km s respectively it is possible to interpret the efficient sn propagation and the relatively normal uppermost mantle p and s velocities beneath a major part of the turkish iranian plateau as indicating a partial underthrusting of the arabian continental plate beneath the iranian and turkish continental blocks alternatively the mapped regions of efficient sn propagation and high sn attenuation may result from a differential cooling of a past thermal anomaly in this case the isostatic compensation of the plateaus could be due to an anomalously hot uppermost mantle that developed behind the mid to upper tertiary subduction zone s in this region and to a subsequent crustal shortening after the collision of the arabian and eurasian plates our results cannot uniquely confirm the validity of the above proposed models

receiver functions for the tien shan analog broadband network contrasts in the evolution of structures across the talasso fergana fault we determined the structure of the crust beneath the central and western tien shan by analyzing broadband 1 20 s analog seismograms of converted p sv phases generated by earthquakes at teleseismic distances and recorded by 14 seismograph stations the one dimensional structures that best explain the waveforms reveal pronounced differences in crustal velocities east and west of the talasso fergana fault specifically the transition zone between the crust and the mantle east of the fault is about 2 times broader than that west of the fault also velocities at depths between 10 and 35 km are about 10 lower in the east although the depth range of these lower velocities is not well resolved the talasso fergana fault is an important boundary for other observables in addition to the structural discontinuities observed at the surface the areas east of the talasso fergana fault are associated with abnormally low mantle velocities outcrops of basalt low q and short wavelength variations in anisotropy integrating these observations we interpret the broad mantle gradient as being due to vertical intrusions of mantle material into the lower crust likewise the low velocities in the midcrust could be thermally induced or due to the introduction of magmatically derived fluids the gross contrast in structure east and west of the talasso fergana fault could reflect a contrast in the dynamics of mountain building in these two regions we postulate that while crustal shortening is the dominant mechanism controlling topography west of the talasso fergana fault vertical uplift caused by a mass deficiency in the upper mantle may contribute significantly to the generation and maintenance of the high elevations east of the fault