slip motion estimation along the ovacik fault near erzincan turkey using ers 1 radar image evidence of important deformation inside the turkish plate abstract a synthetic aperture radar ers 1 scene used to complement a landsat tm scene allows better understanding of the structure of the active ovacik fault southwest of erzincan turkey the radar image shows that the ovacik fault is interrupted at its crossing point with the kemaliye fault recent compressive displacements have reactivated the kemaliye fault while a pull apart basin has been generated along the ovacik fault estimates of offsets of major rivers and analysis of the complex fault geometry given an estimated left lateral strike slip displacement of 12 5 20 km along the ovacik fault for the last 13 ma which is similar to the rate of movement along the east anatolian fault located in the east and forming the boundary of the turkish plate

global positioning system measurements of present day crustal movements in the arabia africa eurasia plate collision zone we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1994 at 54 sites extending east west from the caucasus mountains of southern russia georgia and armenia to the aegean coast of turkey and north south from the southern edge of the eurasian plate pontus block to the northern edge of the arabian platform viewed from a eurasia fixed reference frame sites on the northern arabian platform move n38 13 w at 20 3 mm yr roughly consistent with the velocity implied by nuvel 1a circuit closure n23 7 w at 24 2 mm yr the motion of arabia appears to be transferred directly to the region of turkey north of the suture however eastern turkey is characterized by distributed deformation while central western turkey is characterized by coherent plate motion involving westward displacement and counterclockwise rotation of the anatolian plate internal deformation within the central part of the anatolian plate is less than 2 mm yr the anatolian plate is decoupled from eurasia along the right lateral strike slip north anatolian fault naf this different response in eastern and western turkey to the collision of arabia may result from the different boundary conditions the hellenic arc forming a free boundary to the west and the asian continent and oceanic lithosphere of the black and caspian seas forming a resistant boundary to the north and east we derive a best fitting euler vector for anatolia eurasia motion of 29 2 0 8 n 32 9 0 4 1 3 0 1 m y the mapped surface trace of the naf corresponds well to a small circle about this pole the new euler vector implies an upper bound for naf slip rate of 30 2 mm yr i e assuming all relative motion is accommodated along the naf using the nuvel 1a euler vector for arabia eurasia and the gps euler vector for anatolia eurasia we determine an arabia anatolia euler vector of 31 2 n 45 2 e 0 9 0 1 m y and an upper bound on the east anatolian fault slip rate of 15 3 mm yr the aegean trough region of western turkey deviates significantly from coherent plate rotation in addition to rotating with anatolia this region shows roughly n s extension at a rate of 14 5 mm yr taken together with satellite laser ranging results along the hellenic arc the contemporary pattern of deformation indicates increasing motions toward the arc suggesting that the westward displacement and counterclockwise rotation of anatolia is driven both by pushing from the arabian plate and by pulling or basal drag associated with the foundering african plate along the hellenic subduction zone

late neogene and active orogenic uplift in the central pontides associated with the north anatolian fault implications for the northern margin of the central anatolian plateau turkey 1 surface uplift at the northern margin of the central anatolian plateau cap is integrally tied to the evolution of the central pontides cp between the north anatolian fault naf and the black sea our regional morphometric and plate kinematic analyses reveal topographic anomalies steep channel gradients and local high relief areas as indicators of ongoing differential surface uplift which is higher in the western cp compared to the eastern cp and fault normal components of geodetic slip vectors and the character of tectonic activity of the naf suggest that stress is accumulated in its broad restraining bend seismic reflection and structural field data show evidence for a deep structural detachment horizon responsible for the formation of an actively northward growing orogenic wedge with a positive flower structure geometry across the cp and the naf taken together the tectonic plate kinematic and geomorphic observations imply that the naf is the main driving mechanism for wedge tectonics and uplift in the cp in addition the naf zone defines the boundary between the extensional cap and the contractional cp the syntectonic deposits within inverted intermontane basins and deeply incised gorges suggest that the formation of relief changes in sedimentary dynamics and 1 km fluvial incision resulted from accelerated uplift starting in the early pliocene the central pontides thus provide an example of an accretionary wedge with surface breaking faults that play a critical role in mountain building processes sedimentary basin development and ensuing lateral growth of a continental plateau since the end of the miocene

neotectonics in the eastern north anatolian fault region turkey advocates crustal extension mapping from sar ers imagery and digital elevation model abstract this paper concerns the neotectonics of the eastern part of the anatolian block bounded respectively to the north and the east by the north anatolian naf and the east anatolian faults eaf meeting at karliova the study is based on imagery of synthetic aperture radar sar scenes acquired by the european remote sensing ers satellite and on views of a digital elevation model dem complemented with fault analysis in the field we show that extensional tectonics associated with transcurrent displacements prevail in the karliova triangle and beyond new local releasing bends or pull apart basins and push up structures along the naf have been demonstrated more importantly anatolia is composed of blocks less than 50 km in width that are tilted and move relative to each other they are compatible with a detachment within the crust of anatolia we argue that an escape wedge has migrated through time from west to east with successive jumps to form the present day karliova triangle at each stage the escape wedge was easterly bounded by a ne sw striking fault zone similar to the eaf in each escape wedge clockwise block rotations predate strike slip tectonics along the n110 e striking naf this is the case for instance for the erzincan basin where the first movements were parallel to the sw striking ovacik fault an early equivalent of the eaf and turned later to the west the detached crustal blocks moved southwestward then westward and extended at the same time in order to occupy the increasing surface within the successive escape wedges this is not the behaviour of simple lateral extrusion of the anatolian lithospheric block induced by forces applied at its boundaries by the adjacent plates but rather that of detached crustal blocks submitted to extension as a consequence of backward retreat of the hellenic slab and buoyancy forces arising from crustal thickness differences

inversion of field data in fault tectonics to obtain the regional stress iii a new rapid direct inversion method by analytical means summary a new method for determining the reduced stress tensor with four degrees of freedom the orientations of the three principal stress axes as well as the ratio of principal stress differences using fault slip data or focal mechanisms of earthquakes is presented from a computational point of view the inversion of fault slip data is made in a direct way by purely analytical means as a result the determination process is extremely fast and adaptable on small microcomputers from a physical point of view the method aims at simultaneously i minimizing the angles between theoretical shear stress and actual slip vector and ii having relative magnitudes of shear stress large enough to induce slip despite rock cohesion and friction examples of application to actual fault slip data sets with good or poor variety of fault slip orientations are shown the double significance of the basic criterion adopted results in a more realistic solution of the inverse problem than the single minimization of the shear stria angle

time lapse imaging at bullwinkle field green canyon 65 offshore gulf of mexico two orthogonal preproduction seismic surveys and a regional seismic survey acquired after eight years of production from the bullwinkle field green canyon 65 gulf of mexico reveal extraordinary seismic differences attributed to production induced changes in rock and fluid properties amplitude reduction of up to 71 occurs where production and log data show that water has replaced hydrocarbons as the oil water contact moved upward separate normalizations of these surveys demonstrate that time lapse results are improved by using seismic surveys acquired in similar orientations also clearer difference images are obtained from comparing lower frequency data sets superior stratigraphic illumination in the dip oriented survey relative to the strike oriented surveys results in nongeological amplitude differences this documents the danger of using dissimilar baseline and monitor surveys for time lapse studies

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

preliminary slip rate estimates for the duzce segment of the north anatolian fault zone from offset geomorphic markers abstract new estimates on the quaternary slip rate of the active transform margin of north anatolia are provided we investigated the area struck by a mw 7 1 earthquake on the 12th of november 1999 that ruptured the duzce fault segment of the north anatolian fault in order to analyze the spectacular tectonically driven cumulative landforms and the drainage pattern settings we carried out a 1 25 000 scale geological and geomorphological mapping along the fault trace we reconstruct and describe as offset geomorphic markers right hand stream deflections and fluvial terraces inset into alluvial fan deposits radiocarbon dating indicates that 100 m stream deflections were built up by the last 7000 yrs of fault activity conversely two documented and correlated late pleistocene fluvial terraces are horizontally offset by 300 and 900 m respectively these were dated by means of optically stimulated luminescence osl to 21 ka bp and 60 ka bp assuming a constant rate of deformation for the duzce fault ages and related offsets translate to consistent slip rates that yield an average slip rate of 15 0 3 2 mm yr for the last 60 ka thus the duzce fault importantly contributes to the north anatolian margin deformation suggesting a present day partitioning of displacement rates with the mudurnu fault to the south and confirming its important role in the seismic hazard of the area

uncertainties in quantitative time lapse seismic analysis most seismic time lapse studies so far have been of a qualitative nature identification of areas with minor or no seismic changes has been used to plan new infill drilling targets increased accuracy in seismic acquisition methods in both conventional streamer surveys and newer methods such as multicomponent sea bed seismic and permanent sensors opens possibilities for the next step quantitative time lapse analysis quantitative methods here mean the estimation of for instance a change in fluid saturation from 20 water to 90 water or the estimation of a pore pressure change of 5 mpa explicit expressions for the uncertainties associated with estimated changes in for instance reservoir pressure and fluid saturation are derived these formulae can be used to compare relative uncertainties between estimated parameters as well as to identify the critical factors in various estimation techniques the importance of accurate rock physics input as well as that of highly repeatable time lapse seismic data is emphasized furthermore uncertainty analysis can be used to find optimal weight factors when the same parameter e g saturation change is estimated by two or three different techniques

late cenozoic tectonics and stratigraphy of northwestern anatolia the effects of the north anatolian fault to the region in northwest anatolia there is a mosaic of different morpho tectonic fragments within the western part of the right lateral strike slip north anatolian fault naf zone these were developed from compressional and extensional tectonic regimes during the paleo and neo tectonic periods of turkish orogenic history a ne sw trending left lateral strike slip fault system adapazari karasu fault extends through the northern part of the sakarya river valley and began to develop within a n s compressional tectonic regime which involved all of northern anatolia during middle eocene to early middle miocene times since the end of middle miocene times this fault system forms a border between a compressional tectonic regime in the eastern area eastwards from the northern part of the sakarya river valley and an extensional tectonic regime in the marmara region to the west the extension caused the development of basins and ridges and the incursions of the mediterranean sea into the site of the future sea of marmara since late miocene times following the initiation in late middle miocene times and the eastward propagation of extension along the western part of the naf a block north anatolian block began to form in the northern anatolia region since the end of pliocene times the adapazari karasu fault constitutes the western boundary of this block which is bounded by the naf in the south the northeast anatolian fault in the east and the south black sea thrust fault in the north the northeastward movement of the north anatolian block caused the formation of a marine connection between the black sea and the aegean mediterranean sea during the pleistocene

long offset time lapse seismic tested on the valhall lofs data conventional time lapse seismic has been less successful for stiff rock reservoir monitoring such as carbonates this is mainly because of the negligible time lapse changes in the seismic properties therefore we propose to use long offset time lapse seismic as an alternative method to estimate small velocity changes more specifically we monitor the maximum amplitude offset that is beyond critical offset the properties of the maximum amplitude offset are similar to critical offset except that they appear for longer offsets and are frequency dependent increased frequency reduces the gap between this offset and the critical offset we find that the maximum amplitude offset is a function of overburden and reservoir velocity and practically independent of density this method requires a velocity increase across the interface that is to be analyzed this criterion usually is satisfied for stiff rock reservoirs also by long offset acquisition we mean typically 1 to 2 km beyond the critical offset for

geodetic determination of the kinematics of central greece with respect to europe implications for eastern mediterranean tectonics we use a new satellite laser ranging global positioning system slr gps solution at seven sites in anatolia and aegea to obtain a better definition of the extrusion motion of the anatolian aegean block with respect to europe we show that this motion can be described in a first approximation by a counterclockwise rotation which transfers most of the motion of arabia to anatolia we combine 78 displacement vectors obtained at common points of two triangulation nets measured in central greece in 1895 and 1975 with the slr gps measurements to compute the velocity field over greece with respect to europe these measurements indicate that central greece is a zone of extension between the anatolian aegean counterclockwise rotation to the south and the northern greece clockwise rotation to the north this extension is principally localized within the gulf of corinth to the east but is distributed to the west we then extrapolate this velocity field to the whole aegea and western anatolia using recently published gps results as well as the slr results the narrow dextral north anatolian fault which limits the velocity field to the north progressively gives way to a much wider boundary zone where extension becomes dominant we show that the collision between the mediterranean ridge and africa began 3 6 ma and we describe the modifications that this collision has produced on the kinematic pattern both in aegea and on the mediterranean ridge

slab detachment beneath eastern anatolia a possible cause for the formation of the north anatolian fault in this paper we discuss the possibility that the north anatolian fault naf results from the deep deformation of the slab beneath the bitlis hellenic subduction zone we described the tectonic evolution of the anatolia aegean area in three main steps before during and after the formation of the naf we remark that the tectonic conditions that are assumed to have triggered the formation of the naf i e collision to the east and extension to the west was already achieved before the onset of that strike slip fault system we also highlight that the formation of the naf was accompanied by the uplift of the turkish iranian plateau and by a surge of volcanism in the eastern anatolia collisional area and probably by the acceleration of the aegean trench retreat we show tomographic images from global p wave model of piromallo and morelli c piromallo a morelli p wave tomography of the mantle under the alpine mediterranean area j geophys res 108 2003 doi 10 1029 2002jb001757 showing that the slab beneath the bitlis collisional belt is not continuous and that its possible rupture pursues to the west at least up to cyprus and possibly up to the eastern end of the hellenic trench all these observations suggest that the plate tectonic re organization occurred in the late miocene early pliocene in the region results from slab break off in the bitlis area and from its lateral propagation to the west this idea is tested in analogue laboratory experiments which confirm that the break of the slab under the collisional belt may trigger 1 the acceleration of slab retreat to the west due to the increase in slab pull force 2 the indentation of the continent in the collisional area and 3 produce the conditions that permit the lateral escape of material towards the west and the formation of the naf

analysis of the north anatolian shear zone in central pontides northern turkey insight for geometries and kinematics of deformation structures in a transpressional zone abstract the western part of the north anatolian shear zone at the southern boundary of the central pontides in turkey was investigated in the kursunlu arac area by means of a geological structural field study in this area the north anatolian shear zone results in a transpressional deformation zone that extends between two master faults striking parallel to the main shear direction the main systems of structures identified in the deformation zone appear to be oriented parallel to the directions predicted by riedel theoretical model nevertheless the strain partitioning is more complicated than predicted by theory the structural analysis suggests a polyphase deformation characterized by a steady component of transcurrence associated with alternance of compression and extension along each of theoretical directions the combination of double verging structures can be observed with folds and thrust surfaces root into high angle shear zones according to flower type geometries the discrepancies of directions kinematics and geometries from theoretical models are due to transpressive and or transtensive nature of the deformation according to the observed outcropping structures we propose a conceptual model for the north anatolian shear zone interpreting it as a crustal scale positive flower structure

rough seas and time lapse seismic time lapse seismic surveying has become an accepted tool for reservoir monitoring applications thus placing a high premium on data repeatability one factor affecting data repeatability is the influence of the rough sea surface on the ghost reflection and the resulting seismic wavelets of the sources and receivers during data analysis the sea surface is normally assumed to be stationary and indeed to be flat the non flatness of the sea surface introduces amplitude and phase perturbations to the source and receiver responses and these can affect the time lapse image we simulated the influence of rough sea surfaces on seismic data acquisition for a typical seismic line with a 48 fold stack a 2 m significant wave height sea introduces rms errors of about 5 10 into the stacked data this level of error is probably not important for structural imaging but could be significant for time lapse surveying when the expected difference anomaly is small the errors are distributed differently for sources and receivers because of the different ways they are towed furthermore the source wavelet is determined by the sea shape at the moment the shot is fired whereas the receiver wavelet is time varying because the sea moves significantly during the seismic record

time lapse seismic surveys in the north sea and their business impact in a time lapse 3 d seismic tl3d project a monitor seismic survey is compared to a base survey ideally the base survey is a 3 d data set acquired before production from the field started normally the monitor survey is acquired after several years of production the observed differences between the base and the monitor survey can be interpreted in terms of changes in fluid saturation and pressure when embarking on a seismic monitoring project it is important to keep the following questions in mind in this article we will answer these questions and illustrate our solutions with two examples what field information might technically be obtained fluid drainage information from tl3d may be used directly to locate fluid fronts in each major flow unit it may also be used to derive lateral variations in permeability of the reservoir and sealing capacity of faults these variations can cause areas of bypassed oil and blocks that are not being drained in general it will help to understand the observed production from the field it is a very powerful method to map production related changes in reservoir fluid saturation and pressure away from the wells tl3d very often reveals some flow behavior that had not been predicted even by history matched flow models this information can be critical to future reservoir development what impact will it have on reservoir management time lapse seismic may be used to optimize the number and location of infill wells to access untapped reserves or to accelerate production ideally this will minimize infill costs and maximize recovery it may also indicate the need to shut off thief zones to avoid premature water or gas breakthrough it will

emplacement of volcanic vents and geodynamics of central anatolia turkey abstract observations on synthetic aperture radar sar scenes of the european remote sensing ers satellite and digital elevation models dems complemented by field structural analysis permit a new understanding of relationships between tectonics and volcanism since the late miocene 10 ma in central anatolia volcanic edifices form elongate stratovolcanoes linear clusters and volcanic ridges they indicate emplacement on tension fractures and tail crack or horsetail features for instance the kara dag volcano is rooted on a tail crack which accommodates a horizontal left lateral throw component at a fault termination caldera complexes of cappadocia are associated with horsetail fault patterns the emplacement of volcanoes also benefits from larger scale tectonic structures the erciyes dag volcano is localized by the sultan saz releasing bend which opens along the sinistral strike slip ecemis fault deformation has been analysed from tension fractures which are perpendicular to the direction of extension and from field structural analysis on a regional scale the tectonic regime responsible for the distribution of volcanic vents in this area of convergence and lateral extrusion is not compression but extension the central taurus range is the thermally uplifted shoulder of the adana cilicia basin which is related to lithosphere thinning westward movements in the northwestern part of the studied area are influenced by the active back arc aegean extension situated to the west farther to the south the direction of motion turns southwest and south under the influence of the opening of the adana cilicia basin we interpreted that extension in the central anatolian plateau is related to crustal blocks moving above sub horizontal detachment surfaces located in the lower crust this is based on several facts the tuz golu fault zone is a within crust detachment the tuz golu basin does not affect the whole lithosphere because otherwise it would have been bordered by thermally uplifted shoulders movements change trend within a small 50 km region

estimation of the pre north anatolian fault zone pseudo paleo topography a key to determining the cumulative offset of major post collisional strike slip faults abstract geometric analysis of the morphological elements in a fault controlled environment is a widely used application to investigate active tectonics in this study we analyze recent topographical data to reconstruct an inherited landform assumed to have been formed and then continuously deformed by multiphase tectonics retracing the steps of this complex evolution would allow for the parameters of the faulting kinematics to be deduced here we present a detailed description of the methodology by both graphical and analytical approaches and provide quantitative data for constraining fault behavior this case study focuses on the high topography of northern anatolia which is believed to have formed during the early miocene by significant uplift subsequent to the major phase of plate collision in this area this paleo topography was later cut and dissected after the initiation of a plate bounding continental strike slip fault zone called the north anatolian fault zone nafz results of our analysis reveal that the southern part of the studied portion of the nafz tilted westward with a maximum uplift of 290 m tilting corrected offsets measured along the nafz show that the average dextral displacement is 72 km however measured offsets increase up to 100 km towards the westernmost portion of the fault zone western part of the almacik block we discuss the possibility of analyzing large scale morphotectonic structures to shed light on some debated points related to the nafz evolution the methods described here can be applied to other post collisional strike slip faults worldwide and also to smaller scale morphological structures

slip distribution along the north anatolian fault associated with the large earthquakes of the period 1939 to 1967 abstract between 1939 and 1967 six large fault ruptures formed a westward migrating sequence of events along a 900 km long nearly continuous portion of the north anatolian fault for these events the 1939 erzincan 1942 niksar erbaa 1943 tosya 1944 bolu gerede 1957 abant and 1967 mudurnu valley earthquakes i have compiled a record of dextral slip which contains nearly 100 points these data indicate that the amount of slip is irregularly distributed along the 1939 to 1967 rupture zone the maximum slip 7 5 m occurred during the 1939 earthquake in the eastern 150 km of the 900 km long rupture zone dextral offsets diminish very abruptly eastward but very gradually westward the rate of westward decrease in the 1939 to 1967 offsets is only slightly greater than the rate of westward decrease of post miocene displacement along the north anatolian fault this suggests that westward decrease in slip can be expected to be a general characteristic of earthquake ruptures along the north anatolian fault in the future nevertheless within the 1939 to 1967 slip distribution there are three regions that had less slip than the neighboring regions these i interpret as possible sites of large future earthquakes one of these seismic gaps has already experienced another earthquake in 1951 and subsequent creep

review of the neotectonics of the eastern turkish armenian plateau by geomorphic analysis of digital elevation model imagery digital elevation model dem images provide synoptic views of the earth s surface allowing the analysis of landforms of still active tectonic and volcanic structures at regional scale a dem at 250 m pixel size constitutes regional scale data particularly efficient to investigate the late miocene quaternary deformation of the eastern turkish armenian plateau in the arabian eurasian area of convergence geomorphic analysis of the dem image associated with review of fault plane solutions of earthquakes show that faults are mostly strike slip with small vertical component here we show that the orientations of the tectonic and volcanic structures fit with a tectonic regime characterized by n s shortening and e w lengthening consistent with westward escape of anatolia perpendicular to the direction of the arabia eurasia shortening the uniform uplift of the plateau the predominance of strike slip faulting the lack of major thrusts and the occurrence of normal faults do not support a model of going on crustal thickening due to intracontinental convergence on the contrary our observations can be better interpreted in terms of lithospheric thinning and mantle upwelling related to gravity escape of anatolia

temperature and leaf wax δ2h records demonstrate seasonal and regional controls on asian monsoon proxies orbital scale precipitation isotope records can elucidate climate forcing mechanisms and provide benchmarks for climate model validation the ability to differentiate the influence of temperature seasonality and vapor transport history on precipitation isotope proxies is critical to both objectives we present a 300 k y leaf wax hydrogen isotope record from the south china sea with the effects of local condensation temperature removed 2 h wax t 2 h wax t reflects annually integrated precipitation 2 h in the pearl river catchment of southeast china depleted 2 h wax t lags minimum precession p min by 1 0 0 7 k y reflecting the influence of maximum summer insolation and minimum winter insolation with a minor influence of global ice volume which lags p min by 3 3 0 4 k y in contrast annually integrated cave 18 o minima in central china 1000 km north of our site lag p min by 2 7 0 3 k y in phase with ice volume minima this phase indicates that precipitation 18 o in central china is more strongly influenced by ice volume forcing at the precession band with a lesser influence of northern hemisphere insolation our new 2 h wax t data demonstrate that precipitation isotopes in asia have strong regional variability interpreting water isotope records within the context of regionally varying temperature seasonality and sensitivity to changing glacial boundary conditions is imperative to understanding asian hydroclimatic change

polyphased block tectonics along the north anatolian fault in the tosya basin area turkey abstract the tosya basin is located in the bending segment of the north anatolian fault naf in turkey we have obtained original observations on the neotectonics from sar ers images digital elevation model dem and field structural analysis regional neogene deformation is characterised by the occurrence of several basins that are superimposed in time and space they result from differently oriented movements since 12 ma including southwestward motion along a fault subparallel to the naf we propose a model of polyphased tectonics related to the displacement of several individualised blocks in the first stage tortonian the north tosya block has moved toward the n250 azimuth parallel to the dextral n70 striking segment of the naf as a consequence a triple junction related compatibility basin was opened at the intersection with a n60 to n30 striking fault this pattern is similar to the karliova corner where the naf and the east anatolian fault meet in the second stage early pliocene middle pleistocene a segment of the former n70 naf was abandoned and the naf propagated eastward to form a n90 striking segment n90 naf cutting the former tosya block and basin into two parts the north tosya block has moved again and this new geometry has permitted a south tosya block to move parallel to the naf but with a higher rate which has induced compression in the tosya basin in the third stage holocene the south tosya block moved toward n240 obliquely to any of the naf segments this has resulted in the formation of two holocene pull apart type basins along the previous n60 to n30 striking fault while extensional faults were formed in the south tosya block estimated dextral displacement along the naf is 5 9 to 8 5 km at this stage this model of blocks moving in different directions including holocene local movements toward n240 means that the naf can be considered not to be a simple transform fault our model implies that the n90 naf was non existent before the early pliocene

opposed shear senses inferred from neotectonic mesofracture systems in the north anatolian fault zone abstract the 1200 km long north anatolian fault zone is a right lateral intracontinental transform boundary which was initiated in the late neogene sediments of pliocene to holocene age in basins between cerkes and erbaa within the convex northwards arc of the fault zone are deformed by syn sedimentary and post depositional mesoscopic faults and joints the mesofractures which strike obliquely to the fault zone include reverse faults normal faults normal shear joints conjugate vertical joints and strike slip faults each type of structure occurs in two geometrical groups one comprises four systems of fractures the other is made up of five systems the directions of secondary compression and or extension inferred from the first group of mesofractures which are restricted to sediments of pliocene to early pleistocene age are interpreted as being related to left lateral shear along the north anatolian fault zone the directions of compression and or extension inferred from the second group of mesofractures which cut sediments of pliocene to late holocene age were generated during right lateral shear the presence of the second group of mesofractures is understandable because they are related to the shear sense which operates at the present day but those interpreted as being related to left lateral shear are more puzzling their development implies one or more reversals of the dominant sense of displacement several tentative models to explain such reversals are proposed including regional and local influences the latter related to mechanical constraints and or the effects of other fault systems

analogue models of second order faults genetically linked to a circular strike slip system abstract sandbox experiments with sand and sand silicone models were performed above a circular strike slip fault to understand the influence of curvature on the development of second order faults riedel r faults appear already at low displacements in the concave side of the circular plate where they always form more numerous they are followed by r faults in the convex side and eventually by throughgoing d faults that join the r faults and that develop parallel to the underlying circular fault the angle between the riedel faults and the trace of the main circular fault at the surface of the models is c 26 on the concave side and 15 on the convex side we infer a larger obliquity of 1 in the concave side of the circular plate which corresponds to a larger transpressional component than in the convex side of the main wrench fault due to the more confined volume of deforming sand in sand experiments most of the faults root into the underlying strike slip fault in sand silicone experiments instead the faults form close to the displacement discontinuity in case of a high displacement rate only uplifted areas are located all along the main fault in sand experiments in sand silicone experiments they are mostly located in wedges defined by the riedel faults and the main wrench fault and the width of these uplifted areas appear to be related to the length and activity of the riedel faults our results differ significantly from those of experiments with straight strike slip faults where strain and second order faults are symmetrically arranged on both sides of the main fault

linking slab break off hellenic trench retreat and uplift of the central and eastern anatolian plateaus abstract the central and eastern anatolian plateaus are integral parts of the world s third largest orogenic plateau in the past decade geophysical surveys have provided insights into the crust lithosphere and mantle beneath eastern anatolia these observations are now accompanied by recent surveys in central anatolia and new data constraining the timing and magnitude of uplift along its northern and southern margins together with predictions from geodynamic models on the effects of various processes on surface deformation and uplift the observations can be integrated to identify probable mechanisms of anatolian plateau growth a changeover from shortening to extension along the southern margin of central anatolia that is coeval with the start of uplift can be most easily associated with oceanic slab break off and tearing this interpretation is supported by tomography deep seismicity or lack thereof and gravity data based on the timing of uplift geophysical and geochemical observations and model predictions slab break off likely occurred first beneath eastern anatolia in middle to late miocene time and propagated westward toward cyprus by the latest miocene alternatively the break off near cyprus could have occurred in late pliocene to early pleistocene time in association with collision of the eratosthenes seamount continental fragment with the subduction zone uplift at the northern margin of central anatolia appears to result from crustal shortening starting in the late miocene or early pliocene which has been linked to the broad restraining bend of the north anatolian fault the uplift history of the interior of central anatolia since the late miocene is unclear although shortening there appears to have ended by the late miocene followed by ne sw extension this change in the deformation style broadly coincides with faster retreat of the hellenic trench as well as uplift of the northern and southern margins of central anatolia these different events throughout the plateau may be linked as faster retreat of the hellenic trench has been predicted to occur after slab break off which could have induced extension of central anatolia and helped to form the north anatolian fault through accelerated westward movement of anatolia relative to eurasia correlative geochronologic evidence that we summarize here supports the hypothesis that the geodynamic activity throughout the aegean anatolian domain starting in latest miocene to early pliocene time defines a series of events that may all be linked to slab break off

seismic inversion tracks in situ combustion a case study from balol oil field india in situ combustion is one of the approaches used for secondary recovery of heavy oil in which time lapse seismic data might be used to track the production process we have analyzed three time lapse seismic surveys carried out at a time interval of one year during pre and postcombustion phases of in situ combustion at the balol field in india interpretation of these land time lapse data using standard seismic amplitude differences in terms of reservoir changes during production and injection can be erroneous the balol data in particular lacked calibration and had poor repeatability we have addressed these issues by demonstrating the applicability of independent prestack inversion of baseline and monitor surveys to derive elastic attributes that help to produce clearer images of fluid movement independent estimates of wavelets from the baseline and two monitor surveys were used in prestack inversion to estimate acoustic impedance shear impedance and poisson s ratio the results show unexpected movement of the thermal front away from the injection wells toward the north and northwest of the injection wells farther from the production wells these results have been confirmed by well production data from the field north and northwest of balol

tectonic interpretations of enigmatic structures in the north anatolian fault zone abstract two geometrically distinct groups of syn sedimentary and post depositional mesofaults and joints cut neogene quaternary sediments in basins situated along the convex northwards arc of the north anatolian fault zone between cerkes and erbaa one group comprises second order fractures interpreted as having developed during episodes of right lateral shear along the fault zone while the morphologically identical fractures in the other group have been interpreted as secondary products of left lateral shear thus apparently implying one or more former episodes of eastwards motion of the anatolian scholle because such a reversal of motion would be counter to the well established westward escape of anatolia the structures have been called anomalous or incompatible alternative hypotheses which have been advanced to explain the development of the anomalous mesofractures include localized reversals related to displacements of rigid blocks acting as buttresses within basins selective operation of intra pull apart strike slip faults stress release the coincidence of the present western sector of the fault with an older left lateral fault zone and the influence of a north turkish neotectonic stress regime

seismic modeling to monitor co2 geological storage the atzbach schwanenstadt gas field 1 we develop a petro elastical numerical methodology to compute realistic synthetic seismograms and analyze the sensitivity of the seismic response when injecting carbon dioxide co2 in a depleted gas reservoir the petro elastical model describes the seismic properties of the reservoir rock saturated with co2 methane and brine and allows us to estimate the distribution and saturation of co2 during the injection process the gas properties as a function of the in situ pressure and temperature conditions are computed with the peng robinson equation of state taking into account the absorption of gas by brine wave attenuation and velocity dispersion are based on the mesoscopic loss mechanism which is simulated by an upscaling procedure to obtain an equivalent viscoelastic medium corresponding to partial saturation at the mesoscopic scale having the equivalent complex and frequency dependent bulk dilatational modulus we include shear attenuation and perform numerical simulations of wave propagation at the macroscale by solving the viscoelastic differential equations using the memory variable approach the pseudo spectral modeling method allows general material variability and provides a complete and accurate characterization of the reservoir the methodology is used to assess the sensitivity of the seismic method for monitoring the co2 geological storage at the atzbach schwanestadt depleted gas field in austria the objective of monitoring is the detection of the co2 plume in the reservoir and possible leakages of co2 the leakages are located at different depths where the co2 is present as gaseous liquid and supercritical phases even though the differences can be very subtle this work shows that seismic monitoring of co2 from the surface is possible while the identification of shallow leakages is feasible the detection of the plume and deep leakages located in the caprock just above the injection formation is more difficult but possible by using repeatability metrics such as the normalized rms nrms images considering real data conditions affected by random noise a reference detection threshold for deep leakages and the co2 plume in the reservoir corresponds to a signal to noise ratio of about 10 db

tectonic analysis of fault slip data sets using data that include the direction and the sense of motion on individual fault surfaces determined by slickenside lineations it is possible to reconstruct reduced stress tensors that correspond to the orientation of stress axes and to the ratio 2 3 1 3 between principal stress values 1 2 3 compression being positive no assumption is made concerning the orientation of fault planes relative to stress axes so that reactived faults are taken into account as well as newly created ones qualitative and quantitative methods for analysis of fault slip data were developed during the last 10 years the practical limitation of the methods and the necessity for critical field observations are emphasized these methods can be applied to focal mechanisms of earthquakes a more complex analysis of heterogeneous data sets involving an iterative separation of different stress systems is also discussed this analysis enables one to distinguish successive faulting events careful qualitative study in the field is in all cases essential

the north anatolian fault zone distributed neogene deformation in its northward convex part abstract the north anatolian fault zone is composed of two almost rectilinear branches which join in a northward convex bend in this bent zone the pontide anatolide collisional system has been cut across by two transpressional belts of fold and thrust and wrench faults of lower neogene age these structures were reactived during the neotectonic period the time of deposition of the pontus group for both of these deformational events and up to the present the tectonic regime remained generally transpressional with a nw se direction of compression and a ne sw direction of extension it is only recently during the upper pleistocene that the dextral wrench faults became more localized and more straight than previously the complexity of the eastern part of the north anatolian fault zone is better understood if one takes into account the role of inherited miocene pliocene transpressional structures

strengthening the virtual source method for time lapse monitoring time lapse monitoring is a powerful tool for tracking subsurface changes resulting from fluid migration conventional time lapse monitoring can be done by observing differences between two seismic surveys over the surveillance period along with the changes in the subsurface differences in the two seismic surveys are also caused by variations in the near surface overburden and acquisition discrepancies the virtual source method monitors below the time varying near surface by redatuming the data down to the subsurface receiver locations it crosscorrelates the signal that results from surface shooting recorded by subsurface receivers placed below the near surface for the mars field data redatuming the recorded response down to the permanently placed ocean bottom cable obc receivers using the virtual source method allows one to reconstruct a survey as if virtualsources were buried at the obc receiver locations and the medium above them were a homogeneous half space separating the recorded wavefields

fluid pressure discrimination in anisotropic reservoir rocks a sensitivity study we investigate how seismic anisotropy influences our ability to distinguish between various production related effects from time lapse seismic data based on rock physics models and ultrasonic core measurements we estimate variations in pp and ps reflectivity at the top reservoir interface for fluid saturation and pore pressure changes the tested scenarios include isotropic shale weak anisotropic shale and highly anisotropic shale layers overlaying either an isotropic reservoir sand layer or a weak anisotropic sand layer we find that for transverse isotropic media with a vertical symmetry axis tiv the effect of weak anisotropy in the cap rock does not lead to significant errors in for instance the simultaneous determination of pore pressure and fluid saturation changes on the other hand changes in seismic anisotropy within the reservoir rock caused by for instance increased fracturing might be detectable from time lapse seismic data a new method using exact expressions for pp and ps reflectivity including tiv anisotropy is used to determine pressure and saturation changes over production time this method is assumed to be more accurate than previous methods

the maras triple junction southern turkey based on digital elevation model and satellite imagery interpretation this paper describes major structures in the area of the triple junction of the african anatolian and arabian plates near maras southern turkey a review of the literature on the paleogeographic evolution since mid cretaceous time leads to the idea of the southern tethys mesogea persisting between anatolia and africa arabia until middle late miocene consequently collision may have started later and northward subducting lithosphere may still exist under anatolia the dead sea fault may have initiated near the first collision between the anatolian continent and the western corner of the african arabian continent at which point it may have propagated southward a digital elevation model spot and landsat mss images and field work suggest relief js mainly related to finite deformation resulting from on going collision that began at around 13 ma the images show that the east anatolian fault does not crosscut the central taurus belt field data argue that this belt is a left lateral oblique slip fault zone the southern contact of anatolia passes north of the amanos range continental par t of the african plate and connects with the misis range to the southwest the adana low plain may be regarded as a basin formed at a releasing bend the karasu fault zone which belongs to the dead sea fault zone seems to be transpressive and in this case the karasu basin is not a graben north of the amanos range the giirun arc is thrust to the north and may be considered the result of local collision of the uplifting amanos range into anatolia the maras triple junction is accompanied by deformations affecting all plates at the regional scale

4d seismic for oil rim monitoring in the central north sea gannet a field a 50 ft oil rim is overlain by a gas cap of variable thickness oil is produced from horizontal wells which initially produced dry oil but as the field became more mature a significant water cut was seen in several wells a dedicated 4d seismic monitor survey was acquired in order to assess the remaining distribution of oil reserves by forward modelling the synthetic seismic response to parameters such as contact movement and residual saturations using 2d and 3d wedge models and comparing the results with real seismic data we are able to decipher the contact movements across the field it is shown that in one part of the field the increased water cut is caused primarily by the vertical displacement of the entire oil rim into the initial gas cap this oil rim displacement produces a very different 4d seismic response from the case of a static gas oil contact and rising oil water contact normal production as a result of these observations we are able to optimize field production by both re perforation of existing wells and by drilling sidetracks into the displaced rim a brown field development opportunity that might otherwise be missed

late cenozoic tectonics and volcanism along the north anatolian fault new structural and geochemical data abstract different types of volcanic activity have developed along the north anatolian fault zone naf in turkey detailed analysis of satellite images and digital elevation models dems and field observations have been made in order to understand the tectonics and the distribution of volcanic vents in the anatolian block some faults are oblique to the naf and delimit extensional escape wedges vents rooted on open tension fractures show that emplacement of the volcanism is related to tensional fracturing of the anatolian continental block which we attribute to the onset of free borders in the south and west along the naf earliest extension 1 is directed s to ssw and the latest 2 towards w to wsw parallel to the sinistral slip along the naf major and trace element geochemical data indicate that the dominant calc alkaline rocks are associated with various alkaline lavas k ar ages of the volcanics range from 22 to 8 5 ma in galatia massif 900 to 100 ka in niksar and 3 to 12 ka in erzincan isotopic and trace element data are interpreted as reflecting a dominantly lithospheric mantle source slightly mixed with asthenospheric liquids most magmas were fractionated and contaminated by continental crust during their ascent 1 and 2 tectono volcanic events have propagated through time and space from west to east the 1 extension is late oligocene in the galatia massif late miocene in niksar and late pliocene in erzincan the 2 extension and strike slip event along the naf began in the late miocene in the galatia massif early pliocene in niksar and quaternary in erzincan signature from an asthenospheric source in the second event in the three regions suggests that an ancient suture zone galatia massif and or the lithospheric naf transform niksar and erzincan have served to channel small quantities of asthenospheric melts existing at the base of the lithosphere

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

review of the tectonics of the levant rift system the structural significance of oblique continental breakup abstract the levant rift system is an elongated series of structural basins that extends for more than 1000 km from the northern red sea to southern anatolia the system consists of three major segments the jordan rift in the south el gharb kara su rift in the north and the lebanese fault splay in between the rifted parts of this structural system are accompanied by intensively uplifted margins that mirror image the basinal pattern namely the deeper the basin the higher its margins and vice versa uplifts also occur along the fault splay section the jordan rift comprises axial basins that diminish in size from the south northwards and are separated from each other by shallow threshold zones along the axis of the rift where the margins are also subdued the lebanese fault splay consists of five faults that emerge from the northern edge of the jordan rift and trend like a fan between the north and the northeast one of these faults connects the jordan and el gharb kara su rifts the levant rift and its uplifted margins started to develop in the middle late miocene and most of the structural development occurred in the plio pleistocene the levant rift system is characterized by its oblique displacement and evidence for both dip slip and strike slip displacement was measured on its faults earthquakes also indicate that same mixed pattern some of them show strike slip offset and others normal it is generally conceded that the amount of normal offset along the boundary faults of the rift system reaches 8 10 km but the lateral displacement is disputed and offsets ranging from 11 to 107 km were suggested assessment of the available data led us to suggest that the sinistral offset along the levant rift system is approximately 10 20 km the similarity between the vertical and the lateral displacements the basin and threshold structural pattern of the rift model experiments in oblique rifting as well as the significant tectonic resemblance to the red sea and the east african rifts indicate that the levant rift is the product of continental breakup and it is probably an emerging oceanic spreading center

recent temporal change in the stress state and modern stress field along the north anatolian fault zone turkey summary the north anatolian fault naf is a dextral strike slip fault which runs about 1400 km from east to west from the karliova triple junction to the aegean domain it was active during the plio quaternary as a consequence of the collision between the eurasian and arabian plates the naf intracontinental deformation zone contributes with the sinistral east anatolian fault to the westward extrusion of anatolia as a consequence of the northward drift of arabia the central naf zone forms a northward convex bend where the eastern naf n110 e trending segment extending from karliova is connected to the western naf n75 e trending segment running to aegea analysing the slip occurring in major earthquakes around the naf we show that the present day stress pattern along the naf agrees with stress magnitude and strike variations from east to west the stress regime along the naf is nnw trending hmax 1 transpression in eastern naf this progressively changes westwards to nw trending 1 transtension in central anatolia this lateral variation means a relative decrease of the hmax magnitude which evolves progressively to an extensional regime 1 vertical around the westernmost naf characterized by a nne trending hmin 3 the drastic change in the tendency of the regional stress state in the north anatolian block from compressional to extensional is effective within the central naf bend the stress regime determined by inversion of slip vectors measured on fault planes of various scales confirms the present day transtensional regime in the central part of the naf bend however the fault kinematic analysis of quaternary stress states within the central naf indicates that this stress state was not continuous throughout the quaternary indeed chronologies of fault slip vectors provide evidence for two distinct quaternary regional strike slip stress states within this zone both states have consistent ne and nw trending 3 and 1 axes respectively but have significantly different r values the change in the strike slip stress regime probably occurred in the middle pleistocene the older mean stress state is characterized by a n142 8 e trending 1 a n52 13 e trending 3 and a mean arithmetic rm value of 0 75 which indicates that the regional stress regime is transpressional the younger strike slip regime is characterized by a n142 14 e 1 axis a n52 10 e 3 axis and a mean rm of 0 24 which indicates the transtensional character for this regime the low r values of the stress deviators related to the recent stress state reflect normal component slips these temporal and spatial stress changes along the naf result from the coeval influence of forces due to the aegean subduction in the west and to the northward drift of arabia in the east over these boundary forces shear is superimposed along the naf which accommodates the anatolia extrusion however the timing of the temporal stress change permits the suggestion that the quaternary stress regime variation in north anatolia is mainly due to the influence of the aegean domain

estimation of thickness and velocity changes of injected carbon dioxide layers from prestack time lapse seismic data in this study we bring together the two main categories of time lapse seismic analysis amplitude analysis and time shift analysis to estimate simultaneously the changes in thickness and velocity of a 4d seismic anomaly the methodology is applied to time lapse seismic monitoring of carbon dioxide c o2 storage at sleipner field norway that shows significant 4d effects the 4d anomalies resulting from c o2 injection appear as a multilayer reflection pattern within the relatively shallow utsira sand this multireflective appearance within the sand layer is interpreted as c o2 layers trapped below thin shale layers because most of the c o2 layers are believed to be thin 0 20 m the interference between top and base of these layers needs to be taken into account in 4d seismic analysis by studying the reflected event from a horizon below the utsira sand we estimate 4d traveltime shifts caused by the presence of the c o2 layer above thishorizon we then combine these traveltime shifts with measur