comparison of frequency of occurrence of earthquakes with slip rates from long term seismicity data the cases of gulf of corinth sea of marmara and dead sea fault zone summary in this article through the comparison of knowledge relating to historical earthquakes with the understanding of present day earthquake mechanics and overall gps slip rates in the eastern mediterranean region it has been possible to obtain an idea of how frequently large earthquakes may be expected in some parts of the region it has also been possible to make an assessment from these early events of slip rates over a long period of time for the gulf of corinth in greece the marmara sea in turkey and the dead sea fault system as well as deriving long term magnitude frequency relations for these same regions it has been demonstrated that slip rates calculated from historical data are in general comparable to those calculated from gps measurements and field observations while the size of historical earthquakes and their uncertainty can be quantified this permits a more reliable estimation of the long term hazard the calculation of which is the concern of the engineering seismologist it has also been shown that in most cases large earthquakes are less frequent when they are estimated from long term data sets rather than from the instrumental period making the notion of recurrence time and of hazard assessment questionable this study focuses on some of the few areas in the world for which long term macroseism information exists and which facilitate this kind of analysis

sedimentary and structural evolution of the northwest arabian red sea margin abstract an investigation of the northwestern margin of the arabian peninsula midyan region provides new insights into the two stage development of the red sea graben system the early red sea suez stage and the later red sea aqaba stage the early stage is characterized by the passive subsidence of a continental graben since the early oligocene after a period of enhanced subsidence of the basin in the early miocene this stage ended at the langhian serra valian boundary 14 ma the later stage was initiated by a release of stresses by strike slip movement along the newly formed aqaba levant transform creation of the new plate boundary was accompanied by stagnation of extension in the gulf of suez branch of the early rift stage strike slip motion on the aqaba levant structure is younger than 14 ma and is recorded by the post langhian compressional structures in the area of the midyan peninsula which developed by transpression along the curved path of a left lateral strike slip fault

historical earthquake activity of the northern part of the dead sea fault zone southern turkey abstract the northern part of the dead sea fault zone is one of the major active neotectonic structures of turkey the main trace of the fault zone called hacipasa fault is mapped in detail in turkey on the basis of morphological and geological evidence such as offset creeks fault surfaces shutter ridges and linear escarpments three trenches were opened on the investigated part of the fault zone trench studies provided evidence for 3 historical earthquakes and comparing trench data with historical earthquake records showed that these earthquakes occurred in 859 ad 1408 and 1872 field evidence palaeoseismological studies and historical earthquake records indicate that the hacipasa fault takes the significant amount of slip in the northern part of the dead sea fault zone in turkey on the basis of palaeoseismological evidence it is suggested that the recurrence interval for surface faulting event is 506 42 years on the hacipasa fault

inversion of complex body waves we have developed a method that inverts seismic body waves to determine the mechanism and rupture pattern of earthquakes the rupture pattern is represented as a sequence of subevents distributed on the fault plane this method is an extension of our earlier method in which the subevent mechanisms were fixed in the new method the subevent mechanisms are determined from the data and are allowed to vary during the sequence when subevent mechanisms are allowed to vary however the inversion often becomes unstable because of the complex trade offs between the mechanism the timing and the location of the subevents many different subevent sequences can explain the same data equally well and it is important to determine the range of allowable solutions some constraints must be imposed on the solution to stabilize the inversion we have developed a procedure to explore the range of allowable solutions and appropriate constraints in this procedure a network of grid points is constructed on the i plane where and i are respectively the onset time and the distance from the epicenter of a subevent the best fit subevent is determined at all grid points then the correlation is computed between the synthetic waveform for each subevent and the observed waveform the correlation as a function of and i and the best fit mechanisms computed at each i grid point depict the character of allowable solutions and facilitate a decision on the appropriate constraints to be imposed on the solution the method is illustrated using the data for the 1976 guatemala earthquake

seismicity at warna reservoir near koyna through 1995 the koyna dam site in western india has been seismically active since its impounding in 1962 the seismicity peaked in 1967 when an earthquake of magnitude 6 3 claimed 200 human lives and caused some damage to the dam itself subsequently bursts of seismicity with m 5 earthquakes have occurred during 1973 1980 and 1993 to 1995 the epicenters during the latest burst are concentrated around the newly impounded warna reservoir 25 km south of koyna several shocks of smaller magnitude have occurred in this area since 1967 under the influence of the koyna shivajisagar reservoir but the impoundment of the warna reservoir to over 60 m has led to the enhanced seismic activity in the region the space time pattern of epicenters located for the period 28 august 1993 to 31 december 1995 clearly delineates two parallel trends in the nne ssw direction the correlation between seismic activity and water levels in both the reservoirs suggests that the present activity was influenced more by the warna than the koyna reservoir the discriminatory characteristics of reservoir induced seismicity based on b value foreshock aftershock pattern and decay rate of aftershocks continue to be valid

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

rate of strike slip motion on the amanos fault karasu valley southern turkey constrained by k ar dating and geochemical analysis of quaternary basalts the left lateral amanos fault follows a 200 km long and up to 2 km high escarpment that bounds the eastern margin of the amanos mountain range and the western margin of the karasu valley in southern turkey just east of the northeastern corner of the mediterranean sea regional kinematic models have reached diverse conclusions as to the role of this fault in accommodating relative motion between either the african and arabian turkish and african or turkish and arabian plates local studies have tried to estimate its slip rate by k ar dating quaternary basalts that erupted within the amanos mountains flowed across it into the karasu valley and have since become offset however these studies have yielded a wide range of results ranging from 0 3 to 15 mm a 1 which do not allow the overall role and significance of this fault in accommodating crustal deformation to be determined we have used the cassignol k ar method to date nine quaternary basalt samples from the vicinity of the southern part of the amanos fault these basalts exhibit a diverse chemistry which we interpret as a consequence varying degrees of partial melting of their source combined with variable crustal contamination this dating allows us to constrain the quaternary slip rate on the amanos fault to 1 0 to 1 6 mm a 1 the dramatic discrepancies between past estimates of this slip rate are partly due to technical difficulties in k ar dating of young basalts by isotope dilution in addition previous studies at the key locality of hacilar have unwittingly dated different chemically distinct flow units of different ages that are juxtaposed this low slip rate indicates that at present the amanos fault takes up a small proportion of the relative motion between the african and arabian plates which is transferred southward to the dead sea fault zone it also provides strong evidence against the long standing view that its slip continues offshore to the southwest along a hypothetical left lateral fault zone located south of cyprus

the syrian arc system an overview abstract a comparison between the ne directed negev and palmyra foreland monoclines of the syrian arc shows strong similarity in both their statigraphy and late mesozoic and cenozoic tectonic history a first phase of simple folding in the senonian was followed by a phase of reverse faulting in the miocene and ended with a phase of post miocene uplift in the style of fault bend fold this triple deformation of the north arabian subplate was contemporaneous with the thrusting of the tauros zagros zone the ne sw direction of the syrian arc as well as many other structures on the african and arabian plates are an inherited ancient feature predating any contact with the eurasian plate the continental drift proposed for turkey and arabia is reviewed and rejected for both the amounts of horizontal displacement of the dead sea rift and the east anatolian fault are estimated to be 45 and 27 km respectively it is suggested that the stress system upon the levant has been nw directed since the late cretaceous to the present time the dead sea rift n s stress direction is a local post miocene response to limited regional shift and to intense uplift

field evidences from northern dead sea fault zone south turkey new findings for the initiation age and slip rate abstract the left lateral strike slip dead sea fault zone dsfz extends from the red sea in the south to the east anatolian fault zone eafz in the north this study examines the northern part of the dsfz around amik basin and presents surface and subsurface geological evidence for the quaternary activity and initiation age of the northernmost dsfz the dsfz extends n s in the south of the amik basin where clear geological and morphological evidence exists for faulting geological observations around amik basin analyses of borehole data and electrical resistivity profiles within the amik basin indicate that the activity of the northern dsfz started after pliocene in the amik basin subsurface data in the basin suggest that the dsfz offsets a pre quaternary basin sinistrally by about 7 9 km the offset pre quaternary basin suggests at least 4 94 0 13 mm year slip rate for the northern part of the dsfz the karasu fault zone kfz extends in an en echelon pattern along the western margin of the karasu valley and it transfers the significant amount of slip from dsfz to the eafz

seismic gravity and magnetic surveys in the central part of the red sea their interpretation and implications for the structure and evolution of the red sea abstract while there is unanimous agreement that the axial part of the red sea has witnessed seafloor spreading since the early pliocene opinions diverge considerably with regard to the situation in the main trough and shelves new high precision data comprising palaeomagnetic seismic gravity magnetic and bathymetric measurements from the central and northern parts of the red sea have been examined to discriminate between the earlier proposed hypotheses and to formulate an evolutionary model for the red sea the results show that oceanic crust extends for about 80 km at 19 n on each side of the spreading axis symmetrical seafloor spreading magnetic anomalies are recognized out to anomaly 3a 6 m y b p between 18 30 and 19 45 n anomaly 2a between 19 45 and 20 n and near 21 n anomaly 2 near 22 n and only anomaly 1 near 23 30 n although anomaly 3a is the oldest recognizable magnetic anomaly the extent and configuration of the oceanic basement as determined from seismic measurements indicate that spreading has started and continued without a hiatus since 10 12 m y b p prior to the initiation of oceanic accretion an extension of 40 55 km i e 50 70 has taken place in the proterozoic continental lithosphere whereas a separation of 70 160 km has occurred during the seafloor spreading phase several lines of evidence indicate that the shelves and the marginal parts of the main trough are of continental nature

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

seismicity faulting and structure of the koyna warna seismic region western india from local earthquake tomography and hypocenter locations although seismicity near koyna reservoir india has persisted for 50 years and includes the largest induced earthquake m 6 3 reported worldwide the seismotectonic framework of the area is not well understood we recorded 1800 earthquakes from 6 january 2010 to 28 may 2010 and located a subset of 343 of the highest quality earthquakes using the tomodd code of zhang and thurber 2003 to better understand the framework we also inverted first arrivals for 3 d vp vs and vp vs and poisson s ratio tomography models of the upper 12 km of the crust epicenters for the recorded earthquakes are located south of the koyna river including a high density cluster that coincides with a shallow depth 1 5 km zone of relatively high vp and low vs also high vp vs and poisson s ratios near warna reservoir this anomalous zone which extends near vertically to at least 8 km depth and laterally northward at least 15 km is likely a water saturated zone of faults under high pore pressures because many of the earthquakes occur on the periphery of the fault zone rather than near its center the observed seismicity velocity correlations are consistent with the concept that many of the earthquakes nucleate in fractures adjacent to the main fault zone due to high pore pressure we interpret our velocity images as showing a series of northwest trending faults locally near the central part of warna reservoir and a major northward trending fault zone north of warna reservoir

five decades of triggered earthquakes in koyna warna region western india a review abstract we review reservoir triggered seismicity rts in the koyna warna region of india since the impoundment of the koyna reservoir in 1962 until the year 2015 we include seismicity that occurred farther south in response to the impoundment of warna reservoir in 1993 about 35 km to the south of koyna reservoir the on going earthquake activity for more than five decades in a small seismic volume of about 30 20 10 km3 has characterized the koyna warna region as globally unique and significant to date 22 earthquakes of m 5 about 200 earthquakes of m 4 and several thousand smaller earthquakes have been recorded by a dense network of stations in the region various seismological geophysical and hydrological studies have been carried out to understand the phenomenon of triggered seismicity including source mechanism fault geometry crustal structure earthquake processes causal relationship with reservoir water level changes and anomalous water level fluctuations in cased bore wells the present review takes stock of all such studies undertaken so far to summarise the understanding on various geo scientific issues and milestone achievements with regard to mechanism of triggered seismicity and source processes fault plane solutions commensurate with geometry of faulting source parameters seismogenic depth crustal structure and the role of reservoir water level two stage increase in seismic energy release coinciding with peaks of annual filling and draining cycle of reservoir with one month delay vis a vis spurt of moderate earthquakes m 5 due to i rapid rise in reservoir level 12 m week ii reservoir water level exceeding the previous maxima and iii duration for which high reservoir level is retained are characteristic features numerical models simulating diffusion of pore fluid pressure fronts during the filling stage of reservoir suggest stress perturbations of the order of 0 75 2 25 bar at hypocentral depth triggering earthquakes on critically stressed pre existing faults in the year 2005 a 13 station digital seismometers network became functional that characterized the distribution of epicentres in the area with increased accuracy and suggested four major seismic zones with well defined clusters scientific drilling carried out recently provide several new information regarding the subsurface geology and structure in the koyna region such as i thickness of deccan traps 933 in the koyna area and 1185 m in the warna area ii presence of granite gneiss basement directly underlying the deccan traps iii absence of infratrappean sediments and iv temperature not exceeding 150 c at hypocentral depth it is planned to establish a deep borehole observatory close to the seismic source zone for direct measurements of physical and mechanical properties of rocks pore fluid pressure hydrology thermal condition and other parameters of an intra plate active fault zone in the near field of earthquakes before during and after their occurrence results from such experiment and long term in situ monitoring of critical parameters would enhance our understanding on the mechanism of triggered earthquakes and the role of reservoir water level fluctuations

observation and inversion of surface wave group velocities across central india abstract surface wave group velocities across central india are measured from computer plots of frequency time analysis using multiple filter technique periods range from 5 to 56 sec for fundamental mode rayleigh wave 5 to 16 sec for first higher mode rayleigh wave and 5 to 49 sec for fundamental mode love wave the wave paths from koyna earthquakes to bokaro cross purely through the peninsular plateau the group velocities for these paths are found to be similar to those of surface waves recorded at poona from earthquake which lie to the northeast of bokaro in sub himalayan regions from this it is concluded that the shield structure of the peninsula extends to the sub himalayan regions to northeast of the peninsular plateu with a negligible part of sedimentary layer group velocities of fundamental mode rayleigh and love waves are also obtained for the paths from koyna earthquakes to shillong and are found to be similar to the above mentioned group velocities except at very low periods where group velocities are affected by the small part of each path through thick sedimentary layer of bengal basin northern limit of this basin sedimentary layer has been identified mean and standard deviation of observed group velocity at each period are obtained for each of rayleigh fundamental rayleigh first higher and love fundamental modes the group velocities closely agree with those obtained earlier for the path between new delhi and kodaikanal and are also found to be similar to those observed in some shield regions monte carlo inversion method is applied and crust and upper mantle structure of the indian shield across central india is obtained crustal structure obtained shows a marked resemblance to the results obtained earlier through body wave study

southernmost outcrops of marine lower tertiary carbonate rocks in ne africa gebel abyad sudan early tertiary carbonates gebel abyad formation are described from an isolated limestone plateau from the northwestern sudan they represent the southernmost outskirts of marine tertiary sediments in northeast africa which can be connected with transgressive regressive cycles of the tethys onto the african craton microfacies studies of the carbonates yielded exclusively shallow marine sediments which dried up temporarily and with changing rates of terrigenous input they contain a low diverse fauna and flora poor in individuals the paleogeographic reconstruction of this isolated occurrence was possible by comparing sediments from southern egypt

late cenozoic stress distribution along the misis range in the anatolian arabian and african plate intersection region se turkey 1 this study defines the mio pliocene to present day stress regime acting at the northeastern mediterranean along the se border of the neogene adana basin along the misis range the inversion of earthquake focal mechanisms shows that the present day state of stress is dominantly a transtension combined the strike slip and extension with a consistent ene n83 e trending hmin 3 axis the inversion slip vectors measured on fault planes and chronologies between striations indicate a consistent strike slip stress regime that varied from transpressional initially to transtensional during pleistocene time with the latter continuing into recent times as indicated by earthquake focal mechanism inversions both states have consistent nnw n15 w trending compatible with nnw arabian drift direction and ene n75 e trending hmax 1 and hmin 3 axes respectively but have significantly different mean arithmetic stress ratio rm values rm 0 75 indicating transpression for the old regional stress regime and rm of 0 20 denoting transtensional for the younger regional stress regime the crosscutting of striations confirms also the change within the strike slip stress regime both stress regimes induce sinistral displacement along the major strike slip fault systems i e east anatolian fault karatas osmaniye fault the temporal stress regime change probably occurred during quaternary time and resulted from coeval influence of the superimposed forces owing to subduction processes in the southwest along the cyprus arc continental collision in the east and westward escape of the anatolian block in the north and west

invsp gathers of local earthquake seismograms an approach for modelling the upper crustal p and s velocity structure summary a new approach is presented here for obtaining invsp gathers of local earthquake seismograms in regions with adequate seismogenic depth range the inverse vertical seismic profiling invsp geometry is in principle quite similar to the up hole surveys of shallow seismic exploration in which shots fired at various depths in boreholes are recorded on the surface at a fixed offset similarly local earthquake seismograms of selected events at different hypocentral depths can be gathered into constant offset invsp sections for various stations of a mobile seismograph network they can be modelled for p and s velocity structure to upper crustal depths at each of the stations in the network with the aid of synthetic seismogram computations using appropriate source mechanisms of the earthquakes used an invsp gather obtained to a depth range of about 10 km at a station with 28 km constant offset is modelled for the upper crustal p and s velocity structure in the koyna warna seismic region in the western indian shield to demonstrate this approach

neogene tectonics and plate convergence in the eastern mediterranean new data from southern turkey data reported here demonstrate that the misis complex of southern turkey comprises a major olistostromic body formed prior to the early miocene and tectonically emplaced upon a structurally imbricated pile of deep and shallow marine sediments of early miocene to pliocene age magmatic rocks forming olistoliths in the misis complex have a back arc geochemical signature and variations in the facies paleoenvironments and paleotransport vectors within the associated sediments provide a record of miocene collisional events in southeast turkey the pseudo accretionary imbrication and structural style of the misis complex are attributed to continued collisional over thrusting but there is evidence within the imbricated stack of late sinistral strike slip faulting that relates to post miocene inception of motion along the east anatolian fault system the new data favor these geodynamic models proposed for the neogene evolution of the northeastern mediterranean that involve oblique convergence and associated strike slip adjustments

the east anatolian fault an oblique collisional belt abstract the tectonic setting for the area around the arabia africa anatolia triple junction is described from combined landsat spot satellite image analysis and field observations since the late miocene the motion along the east anatolian fault generated major structures corresponding to shortening with a sinistral slip component the 150 km wide area of the triple junction is highly deformed by folding and thrusting distributed mainly on the border of the anatolian block in addition kinematic reconstructions confirm that the arabia anatolia relative motion is both sinistral and convergent the sinistral strike slip faults of the east anatolian fault zone are of second order and local consequences of the n s arabia anatolia collision

periodic variation of stress field in the koyna warna reservoir triggered seismic zone inferred from focal mechanism studies abstract the koyna warna region in western india is globally recognized as the premier site of reservoir triggered seismicity rts associated with the koyna and warna reservoirs the region is characterized by continuous seismic activity observed since several decades including the world s largest triggered earthquake of m6 3 which occurred in koyna in 1967 while the role of reservoirs in triggering earthquakes has been widely discussed the actual tectonic mechanism controlling earthquake genesis in this region is hardly understood the koyna warna region is exclusively governed by earthquakes of strike slip and normal fault mechanism distinct from the thrust faulting seen in other active zones in the indian region in the present study a comprehensive catalog of 50 focal mechanism solutions of earthquakes that occurred during the last 45 years in the koyna warna region is developed both from previous literature and from moment tensor inversion studies by the authors using broadband data from a local seismic network operating since 2005 the seismicity and fault plane data have enabled precise delineation of trends of the major causative faults which are further accentuated using the double difference technique stress inversion of the focal mechanism data has provided the best fitting principal compressive and tensile stress field of the region which in conjunction with the deciphered fault zones provides a feasible model of seismogenesis in this region based on the observed temporal variation of faulting mechanism a model of alternating cycles of predominantly strike slip and normal faulting is proposed which is attributed to a periodic peaking and relaxation respectively of the horizontal compressive stress field in this region due to the indian plate collision with eurasia

internal structure of the dead sea leaky transform rift in relation to plate kinematics abstract the structures along the dead sea transform rift are related to the motions of the sinai and arabia plates which border it and to the irregularities of their boundaries the total slip was 105 km left lateral but the present structures were formed mainly during the last 40 km of slip which probably occurred in the plio pleistocene along the southern half of the transform the strike slip motion takes place on en echelon faults this produces rhomb shaped grabens or pull aparts which are sometimes composite and in which there is local crustal separation thus much of the transform is leaky these structures occur in a morpho tectonic rift valley delimited by normal faults which express a small component of transverse extension along a few segments the shape of the transform is such that lateral motion produces local transverse compression the geometric relations of the structures along the transform define an eulerian pole of relative plate motions at 32 8 n 22 6 e 0 5 the older motion was somewhat different and is described by a pole located about 5 west of the above then the component of transverse extension and crustal separation was much smaller than now while local transverse compression was more important the northern half of the dead sea transform has an irregular shape and the bordering plates did not remain rigid as lateral motion continued here transverse compression is often important

fault interaction and earthquake triggering in the koyna warna region india 1 earthquakes in the koyna warna region of peninsular india are considered to be reservoir triggered however analyses of the available earthquake data indicate that the sustained high seismicity in this region may be influenced also by the geometry of the fault zones and their interactions through stress transfer these distinct fault zones inferred from the earthquake distribution and their focal mechanisms are favourably oriented to each other in such a way that earthquake occurrences in one of the fault zones increase static stress on the other facilitating frequent and continuing occurrence of earthquakes in the region here we show that though the effect of reservoir operations do promote slip on these faults stress triggering appears to be an important cause for continuing high seismicity as it brings some of the stabilized faults closer to failure in the manner consistent with the inferred sense of motion

advancement in source estimation techniques using broadband regional seismograms one important constraint on source retrieval from regional seismograms comes from the amplitude difference between various phases such as pnl surface wave sv sh because the misfit errors used in some waveform inversions are normalized by the data and synthetics the amplitude information in the data has not been fully utilized in this article we modify the cut and paste source estimation technique zhao and helmberger 1994 by removing this type of normalization it is shown that the modified method increases the stability and resolution of inversion when multiple stations at different distance ranges are used a distance scaling factor is introduced to compensate for the amplitude decay with distance by applying the technique to the terrascope data we have determined source mechanisms and depths of 335 southern californian events with m l 3 5 the amplitude decays with distance are r 1 13 for pnl r 0 55 for love waves and r 0 74 for rayleigh waves in contrast to generally shallow source depths reported by the southern california short period network the depth distribution from waveform inversion shows a strong peak around 12 km with few earthquakes occurring above 5 km and below 20 km

present day seismicity and seismotectonics of the cilician basin eastern mediterranean region of turkey the nature of the interaction between the anatolian arabian and af rican plates is an important problem of northeastern mediterranean tectonics the dead sea fault and east anatolian fault zone are the most prominent structural elements in this region the cilician basin which is located at the junction of these faults is known to have a very active seismic history however instrumental obser vations have been insufficient because of the lack of an adequate local seismic net work to monitor ongoing seismic activity and to analyze the seismotectonics of the cilician region 36 to 38 n 34 to 38 e a digital seismic network of 18 stations with velocity transducers has been operated by the earth and marine sciences re search institute emsri of the scientific and technical research council of turkey tubitak since 1993 no previous studies have been carried out in this region for crustal structure an optimum 1d velocity model was obtained by using the velest algorithm for reliable determination of earthquake hypocenter locations approxi mately 2500 earthquakes detected between 1993 and 2002 with local magnitude greater than 1 5 have been located by using this optimum velocity model the most notable feature of the epicentral distribution is the presence of dense clusters of activity along local fault trends the majority of hypocentral depths of the events range between 5 and 35 km single fault plane solutions of reliable events were calculated in order to analyze the seismotectonic characteristics of the region results show that the cilicia region constitutes a wide left lateral shearing zone that indicates a diffuse plate boundary between the african arabian and anatolian plates

an inverse problem in microtectonics for the determination of stress tensors from fault striation analysis abstract a method is proposed to compute some characteristics of a possible stress tensor related to striations measured in a given faulted area if several tectonic phases are responsible for the striations the method separates and determines the successive stress tensors the iterative algorithm consists of alternatively a sorting the data attributed to a tectonic phase and b computing the characteristics of the stress tensor of this phase the method is tested using an application to synthetic and actual data

an inversion method to analyze the rupture processes of earthquakes using near field seismograms a new and very practical nonlinear least square inversion method has been developed to investigate the dislocation distribution and the character of rupture propagation on an earthquake fault plane the problem is parameterized using a model in which the fault is composed of subfaults which start rupturing with arbitrary magnitudes at arbitrary times the performance of the method is examined by numerical simulations and the method proves useful for the analysis of source processes of earthquakes including complicated cases such as multiple events the source process of the naganoken seibu earthquake of 1984 has been analyzed using strong motion seismograms the dislocation distribution and the character of rupture propagation have been successfully obtained

evolution of neotectonic activity of east anatolian fault system eafs in bingol pull apart basin based on fractal dimension and morphometric indices abstract this study is an attempt of a semi automatic geomorphological gis analysis based on morphometric indices in the study 10 m resolution digital elevation models dems are used to assess the neotectonic signals regarding the recent topographic developments and to attach additional significance to active tectonics in the bingol basin area the methodology incorporates the determination of the structural similarities of the faults in the basins using fractal concepts and the application of four morphometric indices stream power index sp multi resolution index of valley bottom flatness mrvbf terrain ruggedness index tri and valley width to height ratio vf in order to detect the deviation from spatial randomness of the applied indices the weighted correlation coefficient moran s i is used and the results are interpreted at a confidence interval of 99 the spatial distribution of integrated index values is evaluated with the tectonically active fault zones in order to determine the probable activity and the structural deformation in the basin the applied methodology reveals that the fractal analysis of the fault lines and the spatial analysis of the morphometric indices proved to be effective tools in analyzing the tectonic influence of the fault system on the basin area within the basin area a relatively lesser degree of tectonic activity is observed in contrast with the high tectonic activity outside the basin

crustal studies of the koyna region using explosion data from deep seismic soundings abstract this study is based on the seismic data collected as a result of explosions carried out during the 1976 and 1978 deep seismic sounding dss field operations in the koyna region these shots were exploded from twelve shot points by the national geophysical research institute along the guhagar chorochi and kelsi loni profiles refraction studies of the records reveal a two layered crust the top layer consists 17 km of granite and the second layer 19 km of basalt giving the average depth of the moho as 36 km in the region the velocities of the phases pg p and pn have been computed as 5 82 0 01 6 61 0 05 and 8 23 0 05 km sec respectively and those of sg s and sn as 3 41 0 00 4 09 0 07 and 4 60 0 08 km sec respectively the shear wave velocity in the basement rock has been found to be lower in comparison with other regions of the peninsular india in some cases reflections were recorded both from the moho as well as from the intermediate layer these reveal a crustal thickness of 39 km with 19 km of granitic and 20 km of basaltic layers coda signal durations from dss explosions recorded by microearthquake seismographs indicate a lateral heterogeneity in the crust on either side of karad in an east west direction

late cenozoic stress evolution along the karasu valley se turkey abstract this study defines the mio pliocene to present day stress regime acting at the northeastern corner of the eastern mediterranean region along the karasu valley i e the amanos range taking in the antakya osmaniye and kahramanmaras provinces the inversion slip vectors measured on fault planes and chronologies between striations indicate that the stress regime varied from transpressional initially to transtensional having consistent nw and ne trending hmax 1 and hmin 3 axes respectively there are significantly different mean stress ratio rm values however the older mean stress state is characterized by n151 11 e trending 1 and n59 12 e trending 3 axes and by a mean arithmetic rm value of 0 76 indicating that the regional stress regime is transpressional the younger stress regime is characterized by n154 8 e trending 1 and n243 8 e trending 3 axes and by a mean arithmetic rm value of 0 17 indicating a transtensional character for this regional stress regime the low r values of the stress deviators related to the recent stress state reflect normal component slips the earthquake focal mechanism inversions confirm that the younger stress regime continues into the recent the inversion identifies a transtensional stress regime representing strike slip and an extensional stress state with a consistent ne trending hmin 3 axis these stress states are characterized by n66 e and n249 e trending 3 axes respectively both significant regional stress regimes induce left lateral displacement along the southern part of the east anatolian fault eaf or amanos fault the temporal change probably in quaternary time within the regional stress regime from transpression to transtension resulted from the coeval influences of subduction processes in the west southwest i e along the cyprus arc continental collision in the east and westward escape of the anatolian block

mantle flow induced crustal thinning in the area between the easternmost part of the anatolian plate and the arabian foreland e turkey deduced from the geological and geophysical data abstract eastern anatolia consisting of an amalgamation of fragments of oceanic and continental lithosphere is a current active intercontinental contractional zone that is still being squeezed and shortened between the arabian and eurasian plates this collisional and contractional zone is being accompanied by the tectonic escape of most of the anatolian plate to the west by major strike slip faulting on the right lateral north anatolian transform fault zone natfz and left lateral east anatolian transform fault zone eatfz which meet at karliova forming an east pointing cusp the present day crust in the area between the easternmost part of the anatolian plate and the arabian foreland gets thinner from north ca 44 km to south ca 36 km relative to its eastern eahp and western sides central anatolian region this thinner crustal area is characterized by shallow cpd 12 16 km very low pn velocities

source parameters of koyna earthquakes india abstract a seismic zone in southwestern india extending 30 km south from koyna dam has witnessed more than 150 earthquakes of m 4 and 10 of m 5 during the last 34 years during august 1993 to december 1994 a spurt of earthquakes occurred in the vicinity of the newly impounded warna reservoir 25 km south of koyna dam the epicenters are located between the two reservoirs but more near the new reservoir during 1994 digital data acquisition systems were deployed by the national geophysical research institute in the vicinity of the koyna warna reservoirs to help in understanding the physical processes responsible for generating earthquakes in the area source parameters were estimated at three stations using s wave spectrum for 193 selected earthquakes of m 1 5 to 4 7 that were recorded during october 1994 to june 1995 seismic moments of 10 11 to 10 16 n m source radii from 94 to 538 m and stress drops of 0 03 to 19 mpa for earthquakes of magnitude 1 5 to 4 7 were obtained from this analysis it is observed that earthquakes of m 3 are associated with larger stress drops of more than 2 mpa the larger energy release through more numbers of m 3 earthquakes and higher stress drop values are found in 0 to 1 km and 5 to 13 km depth ranges depth range of 1 to 4 km has low seismicity and low stress drop earthquakes higher energy release and stress drops are possibly caused by higher stress concentration and incremental stress on rocks with fluids in subhydrostatic conditions in 0 to 1 km depth range and suprahydrostatic conditions in 5 to 13 km depth range spatially the earthquakes of m 3 and high stress drop are now less near koyna reservoir but frequent near the new reservoir

geochemical characteristics of soil radon and carbon dioxide within the dead sea fault and karasu fault in the amik basin hatay turkey abstract the study area is close to the boundary of three tectonic plates anatolian arabian and african plates and is characterized by important tectonic lineaments which consist mainly of the dead sea fault dsf the karasu fault and the east anatolian fault eaf systems to understand the origin of soil gas emanation and its relationships with the tectonics of the amik basin hatay a detailed soil gas sampling was systematically performed together with co2 flux measurements 220 soil gas samples were analyzed for rn and co2 concentrations the distribution of soil rn kbq m3 co2 concentration ppm and co2 flux g m2 day in the area appears as a point source spot and or diffuses halo anomalies along the buried faults fractures due to crustal leaks the results revealed that rn and co2 concentrations in the soil gas show anomalous values at the specific positions in the amik basin the trace of these anomalous values is coincident with the n s trending dsf co2 is believed to act as a carrier for rn gas based on the rn and co2 concentrations of soil gases at least three gas components are required to explain the observed variations in addition to the atmospheric component two other gas sources can be recognized one is the deep crust component which exhibits high rn and co2 concentrations and is considered the best indicator for the surface location of fault fracture zones in the region the other component is a shallower gas source with high rn concentration and low co2 concentration moreover he isotopic compositions of representative samples vary from 0 94 to 0 99 ra illustrating that most samples have a soil air component and may have mixed with some crustal component without significant input of the mantle component based on the repeated measurements at a few sites soil gas concentrations at the same site were observed to be higher in 2014 than in 2013 which may be associated with the activity of the dsf in 2013 2014 this suggests that soil gas variations at fault zone are closely related to the local crustal stress and hence are suitable for monitoring fault activities

mis 5a and mis 3 relatively high sea level stands on the hatay samandag coast eastern mediterranean turkey abstract the coastal belt of hatay samandag in the east mediterranean is marked by the intersection of the african arabian and eurasian anatolian platelet plates where several quaternary shorelines related to relative sea level changes can be seen above the current sea level in this study the most common and best preserved high sea level markers of the marine isotope stage mis 5 and mis 3 shorelines were dated for the first time using the mollusc based electron spin resonance esr method as a result of this research the age of the late mis 5 and mis 3 sea level highstands in the eastern mediterranean the elevation of the corresponding shoreline at samandag coast and the vertical component of the late quaternary tectonic movements which has an impact on shoreline were determined the shorelines at 48 43 m elevations between cevlik and samandag at 58 6 m in tekebasi and at 21 m at keldag have been dated to approximately 72 ka and therefore are correlated with mis 5a the shoreline at 40 39 m elevations between cevlik and samandag has been dated to approximately 53 ka and therefore is correlated with mis 3 according to the position of the mis 5a shorelines the uplift rate over the last 72 ka was 0 88 mm y between cevlik and samandag 1 08 mm y in tekebasi and 0 56 mm y in keldag yielding a 0 84 mm y average this rather fast uplift appears to be related to the vertical component of the strike slip active faults in the samandag antakya fault zone

spatial variations of the fractal properties of seismicity in the anatolian fault zones abstract the anatolian fault zones are seismically active strike slip fault zones transcending the anatolian plate in e w and n s directions we investigate the spatial variations of seismicity along these zones in an attempt to investigate fault complexity along strike quantified by the gutenberg richter b value and the fractal correlation dimension of earthquake epicentres using the maximum likelihood method and the correlation integral respectively the investigation covers instrumentally recorded carthquakes of magnitude m 4 5 occurring between 1900 and 1992 we find systematic spatial variations which may be related to structural or mechanical variability along strike in particular the large change in strike at the northern apex of the north anatolian fault zone is associated with the highest correlation dimension and lowest b value for seismicity this century the correlation dimension and b value show a negative correlation with respect to each other similar to results reported in other regional studies of japan and southern california this statistical correlation is stronger when more objective seismic zoning is carried out based on number of events rather than more subjective seismotectonic zoning in common use in seismic hazard analysis

geochemical approach to magmatic evolution of mt erciyes stratovolcano central anatolia turkey erciyes stratovolcano culminating at 3917 m is located in the cappadocian region of central anatolia during its evolution this quaternary volcano produced pyroclastic deposits and lava flows the great majority of these products are calc alkaline in character and they constitute kocdag and erciyes sequences by repeated activities alkaline activity is mainly observed in the first stages of kocdag and approximately first middle stages of erciyes sequences generally kocdag and erciyes stages terminate by pyroclastic activities the composition of lavas ranges from basalt to rhyolite 48 4 70 5 wt sio calc alkaline rocks are represented mostly by andesites and dacites some compositional 2 differences between alkaline basaltic basaltic and andesitic rocks were found while the composition of dacites remain unchanged all these volcanics are generally enriched in lil and hfs elements relative to the orogenic values except rb ba nb depleted alkaline basalt 87 srr 86 sr and 143 ndr 144 nd isotopic composition of the volcanics range between 0 703344 0 703964 0 512920 0 512780 for alkaline basalts and change between 0 704322 0 705088 0 512731 0 512630 for alkaline basaltic rocks whereas calc alkaline rocks have relatively high sr and nd isotopic ratios 0 703434 0 705468 0 512942 0 512600 low rb ba nb content with high zrrnb low barnb laryb ratio and low sr isotopic composition suggest an depleted source component while high ba rb nb content with high laryb barnb low zrrnb and low 87 srr 86 sr ratios indicate an oib like mantle source for the generation of erciyes alkaline magma these elemental and ratio variations also indicate that the different mantle sources have undergone different degree of partial melting episodes the depletion in ba rb nb content may be explained by the removal of these elements from the source by slab derived fluids which were released from pre collisional subduction modified the asthenospheric mantle the chemically different mantle sources interacted with crustal materials to produce calc alkaline magma the barnb increase of calc alkaline samples indicates the increasing input of crustal components to erciyes volcanics sr and nd isotopic compositions and elevated lil and hfs element content imply that calc alkaline magma may be derived from mixing of an oib like mantle melts with a subduction modified asthenospheric mantle and involvement of crustal materials in intraplate environments q 1998 elsevier science b v all rights reserved

palaeomagnetic study of tertiary volcanic domains in southern turkey and neogene anticlockwise rotation of the arabian plate abstract following collision with eurasia the arabian shield indenter has continued to deform into the weak anatolian collisional collage that resulted from subduction of the neotethyan ocean differential movements have involved rotation and continuing northwards translation and have been accommodated mainly by slip along major transforms including the northward extension of the dead sea fault zone dsfz and the east anatolian fault zone eafz to aid in evaluating post collisional motions the palaeomagnetism of extensive volcanic domains at the northern margin of the stable shield in southern turkey is reported here together with the timing of emplacement as constrained by k ar study the age dating results indicate that volcanic activity occurred mainly during mid late miocene times corresponding to the final stages of suturing volcanic fields in the east of the investigated region are younger and correspond to neotectonic volcanism in brunhes and matuyama chrons thermal and alternating field demagnetization of 399 cores from 83 sites in basaltic lavas identifies 29 units of normal and 43 of reversed polarity with 11 sites having transitional or random directions volcanic fields west of the euphrates kilis gaziantep region with ages in the range 7 0 20 3 ma average 14 9 ma sd 4 3 ma have mean remanence d i 353 52 38 sites 5 3 lava fields east of the euphrates urfa region are dated 10 4 12 1 ma and yield a comparable mean remanence d i 350 50 17 sites 6 0 these collections are shown to have properly recorded palaeosecular variation with only minimal inclination shallowing and inferred anticlockwise rotations with respect to eurasia since mid miocene times are 10 9 4 3 and 14 0 5 0 respectively these contrast with clockwise rotation of 6 3 4 3 derived from late matuyama brunhes epoch volcanic rocks immediately to the north west of the arabian margin where rotational impingement of the shield indenter into fault blocks within the karasu rift at the northern extension of the dsfz interacts with left lateral motion at a rate of 0 5 cm year along this zone to produce small scale vertical axis rotations results from the volcanic suites sited on the stable shield are compared with other results from the arabian plate to conclude that it did not rotate significantly following closure of the bitlis suture until late miocene early pliocene times since when it has rotated anticlockwise at a rate of 1 0 myr this is comparable to the present day rate of rotation deduced from gps and correlates with crustal separation and sea floor spreading in the red sea it also temporally links the rotation of the arabian plate to the initiation of the intracontinental transforms north and east anatolian fault zones within anatolia and to the subsequent extrusion of blocks within this accretionary domain by tectonic escape to the west

evidence of low magnitude continued reservoir induced seismicity associated with the pertusillo artificial lake southern italy the most common observations of reservoir induced seismicity ris by filling artificial lakes are generally associated with the initial impoundment of the lake or the lake level increase above a previous maximum rarely ris persists for many years without a decrease in frequency or magnitude if this occurs it is called protracted or continued seismicity pertusillo artificial lake in high agri valley southern italy is a small reservoir with a water column that fluctuates yearly by about 10 15 m on average corresponding to a pressure perturbation at the bottom of the lake of 0 10 0 15 mpa although the reservoir was filled in 1963 the microearthquake activity still occurring around the lake allows the categorization of such ris as continued seismicity we collected all microearthquakes m l 2 7 recorded near the reservoir by two different seismic networks from january 2005 to june 2012 and analyzed their frequency magnitude distribution which showed a b value b 1 40 much higher than that expected for the investigated area even though the spatial seismicity pattern shows two distinct clusters to the northeast and southwest of the lake we found that only the southwest seismicity is significantly correlated with the water level the findings suggest that the physical driving mechanism is the 1d pore fluid pressure diffusion along the northeast southwest fault zones connecting the reservoir to the southern termination of the monti della maddalena fault system with an average hydraulic diffusivity of 7 8 m2 s online material figures of magnitude comparisons between catalogs temporal occurrence of events rainfall versus number of earthquakes and number of events versus water level and animated 3d views of seismicity and reservoir

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

the caucasus an actual example of the initial stages of continental collision abstract a field study of the neotectonics of the georgian caucasus is combined with geophysical geodetic and geological information in order to obtain a mechanical model of actual deformation the analysis of satellite photos together with topographical and geological maps shows that the great caucasus is bisected by a nne trending sinistral strike slip fault zone the western great caucasus is thrusted to the south over the rioni basin while on the other hand its northern flank is a monocline that descends gently into the russian platform active volcanism is present from elbruz to kazbeg the eastern great caucasus is limited by thrusts to the north and to the south and intermediate structures are disposed in a fan like shape no recent volcanism is observed the eastern limit of the chain is a nnw trending dextral strike slip fault zone seismicity from a local network illustrates the activity of the thrusts and gives evidence for the strike slip faults microtectonic data confirm the recent activity and the sinistral character of the borjomi kazbeg strike slip fault the strike slip faults bordering the eastern caucasus may be seen as the limits of a plastic wedge in front of the arabian plate at an early stage of continental collision

crustal structure from deep seismic soundings along the koyna ii kelsi loni profile in the deccan trap area india abstract the crustal depth section obtained from deep seismic soundings along the koyna ii kelsi loni profile which lies near latitude 18 n roughly in the east west direction in that part of the deccan trap maharashtra state india shows a number of reflection segments below the deccan traps down to the moho discontinuity a deep fault below the deccan traps 13 km east of mahad divides the entire cross section including the moho boundary into two crustal blocks the reflection segments show updip towards the west coast in the western block the moho discontinuity which is at a depth of 39 km near the deep fault starts rising towards the coast reaching a depth of 31 5 km at the west coast the eastern block is thrown up by 1 5 km with respect to the western block along the deep fault a structural contour map of the moho discontinuity for the koyna reservoir area has been prepared from the present results and the crustal information obtained along the koyna i profile kaila et al 1979a shows that the deep fault in the koyna area is aligned in the nnw sse direction refraction seismic data analysis by the wave front method reveals that the thickness of the deccan trap increases towards the west coast the deccan trap is 600 700 m thick in the eastern region between nira sp 130 and loni sp 200 and attains a thickness of 1500 m at 10 km east of the west coast the longitudinal wave velocity in the deccan traps along the profile varies from 4 8 to 5 0 km sec and in the crystalline basement from 6 0 to 6 15 km sec a tentative isopach contour map of the deccan traps and a tentative structural contour map of the pre deccan trap contact have been prepared for the koyna reservoir area from the results along the koyna ii and koyna i profiles a flexure aligned in a nnw sse direction in the pre deccan trap contact which is an expression of the deep fault into the basement has been clearly brought out the flexure coincides in general with the orientation of the deccan volcanic scarp in this area

source inversion of seismic waveforms the koyna india earthquakes of 13 september 1967 abstract the treatment of the seismic source inverse problem when diverse forms of waveform data are available is simple and elegant using a moment tensor formalism if earth structure is known and its effects predictable in terms of vertically inhomogeneous elastic layered models then all types of wave phenomena e g surface waves body waves leaky modes etc for a purely deviatoric moment tensor point source may be represented by at most a sum of three green9s functions for an arbitrary symmetric moment tensor point source one additional green9s function is needed for the p sv system however elegant this formalism may be for posing the linear inverse problem the major difficulties lie in earth structure unknowns and resultant nonlinearities in the green9s functions which can cause significant trade offs with source parameters a hybrid inversion procedure is set up to gain insight into the probable unknowns in particular problems by incorporating both a linearized least squares gradient method for the moment tensor or double couple and smoothed time function parameters and a nonlinear systematic trial and error search for moment tensor or double couple parameters for several assumptions of green9s function the inversion technique is applied to near regional waveform data from a small earthquake associated with the koyna reservoir which occurred 13 september 1967 as the second in a group of three events with very similar waveshapes but differing amplitudes the magnitudes of the second and third events are smaller by 0 2 and 0 8 units respectively compared to the first the absolute magnitude for the first event is poorly constrained but is estimated to be 4 0 to 4 5 rather than the previously published value of 5 5 to 6 0 from the similarity of waveshapes all three events are inferred to have the same mechanism and occurred within about 2 km of the same hypocenter the results from moment tensor and double couple inversions for event 2 data indicate that source depth was 5 km and that left lateral faulting occurred on a plane with a strike of n20 e 5 dip of 90 15 and a rake of 0 35 the inferred far field time function is approximately 3 sec in duration unusually long for the seismic moment of 9 10 22 dyne cm yielding a possible stress drop of about 0 05 bars a fault map was constructed from landsat image interpretation and shows a predominance of nnw to nne striking faults in the koyna area which is used to infer the appropriate nodal plane in the inversion results these faults tend to define a broad en echelon zone which parallels the western ghats in this area

active tectonics of the alpine himalayan belt between western turkey and pakistan summary over 80 new fault plane solutions combined with satellite imagery as well as both modern and historical observations of earthquake faulting are used to investigate the active tectonics of the middle east between western turkey and pakistan the deformation of the western part of this region is dominated by the movement of continental material laterally away from the lake van region in eastern turkey this movement helps to avoid crustal thickening in the van region and allows some of the shortening between arabia and eurasia to be taken up by the thrusting of continental material over oceanic type basement in the southern caspian mediterranean makran and black sea thus central turkey bounded by the north and east anatolian strike slip faults is moving west from the van region and overrides the eastern mediterranean at two intermediate depth seismic zones one extending between antalya bay and southern cyprus and the other further west in the hellenic trench the motion of northern iran eastwards from the van region is achieved mainly by a conjugate system of strike slip faults and leads to the low angle thrusting of iran over the southern caspian sea the seismicity of the caucasus shows predominantly shortening perpendicular to the regional strike but there is also some minor elongation along the strike of the belt as the causcasus overrides the caspian and black seas the deformation of the eastern part of this region is dominated by the shortening of iran against the stable borders of turkmenistan and afghanistan the north east direction of compression seen in zagros is also seen in north east iran and the kopet dag where the shortening is taken up by a combination of strike slip and thrust faulting large structural as well as palaeomagnetic rotations are likely to have occurred in ne iran as a result of this style of deformation north south strike slip faults in southern iran allow some movement of material away from the collision zone in ne iran towards the makran subduction zone where genuinely intermediate depth seismicity is seen within this broad deforming belt large areas such as central turkey nw iran azerbaijan central iran and the southern caspian appear to be almost aseismic and therefore to behave as relatively rigid blocks surrounded by active belts 200 300 km wide the motion of these blocks can usefully be described by poles of rotation the poles presented in this paper predict motions consistent with those observed and also predict the opening of the gulf of iskenderun ne of cyprus the change within the zagros mountains from strike slip faulting in the nw to intense thrusting in the se and the relatively feeble seismicity in se iran baluchistan this description also explains why the north south structures along the iran afghanistan border do not cut the east west ranges of the makran within the active belts surrounding the relatively aseismic blocks a continuum approach is needed for a description of the deformation even though motions at the surface may be concentrated on faults the evolution of fault systems within the active zones is controlled by geometric constraints such as the requirement that simultaneously active faults do not in general intersect many of the active processes discussed in this paper particularly large scale rotations and lateral movement along the regional strike are likely to have caused substantial complexities in older mountain belts and should be accounted for in any reconstructions of them

depth of faulting during the 1968 meckering australia earthquake sequence determined from waveform analysis of local seismograms waveforms for 11 foreshocks and 48 aftershocks of the ms 6 8 meckering earthquake recorded at the world wide standard seismograph network station mundaring are analyzed to determine the depth distribtion of faulting during this unusual intraplate earthquake sequence clear depth phases including sp and rg are seen in the local seismograms at distances of 60 95 km and are studied using synthetic seismograms computed using generalized ray theory and wave number integration techniques large rg s ratios seen on the vertical component short period data for many events imply source depths less than 2 km the short period p waveform contains the best depth estimator in the form of sp so that depth can be estimated to within an uncertainty of about 1 km for most events the foreshocks cluster at less than 2 km depth and most aftershocks occur within 1 km of the surface a few aftershocks occur as deep as 7 km these results are consistent with a previous teleseismic waveform study in which faulting was inferred to start near the surface at 1 5 km depth with rupture proceeding downward and not exceeding 6 km depth these results coupled with previous stress studies in the australian shield and models of crustal strength show that faulting in a cold shield area is a near surface phenomenon and implies that most of the crust is too strong to be fractured

source estimation from broadband regional seismograms recently developed source inversion techniques do not take full advantage of the broadband nature of regional seismograms the reason is that green s functions generated from flat layered models are not correct for the complicated propagational phenomena associated with realistic crustal structure the inversion is usually performed by removing short periods and inverting only selected portions of the records in this article we introduce a source estimation technique that allows for better use of the entire broadband record when only imperfect green s function are available the procedure desensitizes the timing between the principal crustal arrivals by fitting portions of the green s functions independently the preferred source is the orientation that minimizes the average l1 and l2 norms in term of the four parameters m 0 strike dip and rake the l2 error emphasizes the longer period surface waves while the l1 error weights the shorter period body waves we obtain estimates of duration by modeling long period and broadband signals the depth determination can be obtained directly from the surface reflected phases sp mp or ss ms or by cycling through the depth dependent green s functions in addition to the source parameters we obtain t phase alignments shifts that can be used as green s function corrections for relocating other events or as a guide to deriving new crustal models

recent volcanism tectonics and plate kinematics near the junction of the african arabian and anatolian plates in the eastern mediterranean abstract in the eastern mediterranean plate convergence occurs between africa arabia and anatolia the africa arabia motion is a strike slip displacement along the dead sea fault the africa anatolia motion is taken up by subduction south of cyprus the convergence between arabia and anatolia is taken up along the east anatolian fault the analysis of the regional fault surfaces reveals the presence of two major tectonic phases that affected southeastern turkey near the junction of these three plates the older deformations are related to a n s compression the more recent movements are directed mainly westward and associated with strike slip and extension tectonics near the triple junction since 2 ma a fissure volcanism produced tholeiite followed by alkali basalt along the amanos fault the northern end segment of the dead sea fault in addition reconstruction of rigid plate kinematics between arabia africa and anatolia using recent plate motion parameters and space geodesy data suggest for the east anatolian fault a slip rate of 7 8 9 mm year the maximum finite displacement recognised for this structure being around 15 km we have obtained 1 9 ma as the maximum age for the fault formation the volcanic tectonic and kinematic data converge to propose a ca 2 ma age for the change of local tectonic regime in the junction area the structural mapping the geometry of the fractures used by the magma to reach the surface and the presence of alkali basalt of mantle source suggest that the deformation along the northern end of the dead sea transform i e the amanos fault was modified by the formation of the east anatolian fault zone in this region apparition of the east anatolian fault accommodating westward motion of the anatolian plate resulted in oblique slip tension along the amanos segment of the dead sea transform giving rise to a fissure fed mantle derived alkaline volcanism at ca 2 ma which lasted until recent times 0 4 ma

investigations related to scientific deep drilling to study reservoir triggered earthquakes at koyna india artificial water reservoir triggered earthquakes have continued at koyna in the deccan traps province india since the impoundment of the shivaji sagar reservoir in 1962 existing models to comprehend the genesis of triggered earthquakes suffer from lack of observations in the near field to investigate further scientific deep drilling and setting up a fault zone observatory at depth of 5 7 km is planned in the koyna area prior to undertaking deep drilling an exploratory phase of investigations has been launched to constrain subsurface geology structure and heat flow regime in the area that provide critical inputs for the design of the deep borehole observatory two core boreholes drilled to depths of 1 522 and 1 196 m have penetrated the deccan traps and sampled the granitic basement in the region for the first time studies on cores provide new and direct information regarding the thickness of the deccan traps the absence of infra trappean sediments and the nature of the underlying basement rocks temperatures estimated at a depth of 6 km in the area made on the basis of heat flow and thermal properties data sets do not exceed 150 c low elevation airborne gravity gradient and magnetic data sets covering 5 012 line km together with high quality magnetotelluric data at 100 stations provide both regional information about the thickness of the deccan traps and the occurrence of localized density heterogeneities and anomalous conductive zones in the vicinity of the hypocentral zone acquisition of airborne lidar data to obtain a high resolution topographic model of the region has been completed over an area of 1 064 km2 centred on the koyna seismic zone seismometers have been deployed in the granitic basement inside two boreholes and are planned in another set of six boreholes to obtain accurate hypocentral locations and constrain the disposition of fault zones

location of the pilot borehole for investigations of reservoir triggered seismicity at koyna india abstract artificial water reservoir triggered earthquakes are now known to have occurred at over 120 sites globally the part played by the reservoirs in triggering is not exactly known due to lack of near field observations of triggered earthquakes koyna located near the west coast of india where triggered earthquakes have been occurring since 1962 provides an excellent site for near field observations of the target m 2 earthquakes a 6 borehole seismic network has been deployed recently in the koyna region at depths of 981 1522 m to improve the hypocenter locations during may december 2015 a total of 1039 earthquakes of m l 0 5 were located using the borehole seismic network the region is also monitored through a dense network of 23 surface broad band stations our analysis indicates a significant improvement in the estimation of absolute locations of earthquakes with errors of the order of 300 m combining both the networks based on seismicity and logistics a block of 2 2 km 2 area has been chosen for drilling the first pilot borehole of 3 km depth where m 2 earthquakes have been occurring frequently since 2005

sedimentology of a late cenozoic collisional sequence the misis complex adana southern turkey abstract this study is concerned with miocene sequences formed within part of the cukurova basin of southern turkey a major downwarp created during the early stages of collision between the afro arabian plate and the tauride anatolian microplate assemblage we report here the results of a combined stratigraphical sedimentological structure and geochemical study of the misis complex a structurally elevated segment of cukurova basin fill this analysis has demonstrated the structurally imbricated nature of the misis sequences and the tectonic juxtaposition of originally well separated coeval facies the initial discernible phase of basin filling pre burdigalian was marked by deep marine conditions and marginal tectonic instability probably related to a late phase of tauride nappe advance the subsequent phase of crustal extension burdigalian early tortonian produced expansion of the cukurova basin limits and an upwards shoaling succession in which sediment transport towards the southwest gradually became dominant as a result of earlier suturing and uplift in northeasterly sectors of the collision zone the miocene arenites of the misis complex are petrographically diverse with common siliciclastic and carbonate detrital admixtures and mineralogically immature and their position in petrotectonic fields indicates a compound provenance from both recycled orogen and magmatic arc sources a noteworthy petrographic feature is the compositional similarity of arenites from both shallow and deep marine facies the general succession of neogene facies observed in the cukurova basin and misis complex is consistent with their evolution within a perisutural foreland basin but this interpretation is complicated by petrographic and geochemical features attributed to remnants of an older magmatic arc later stages of basin filling are also marked by the local occurrence of anomalous palaeoenvironmental associations including olistostromic units attributed to contemporaneous intra basinal tectonism

cenozoic tectonic evolution of asia a preliminary synthesis abstract asia has been a major testing ground for various competing models of continental deformation due to its relatively well understood plate boundary conditions in the cenozoic exceptional exposure of active structures and strain distribution and widespread syn collisional igneous activity as a proxy for the thermal state of the mantle and crust two cenozoic orogens dominate the continent the himalayan tibetan orogen in the east induced by the india asia collision and the turkish iranian caucasus orogen in the west induced by the arabia asia collision the development of the two orogens was accomplished by shortening in the early stage followed by strike slip faulting and extension in the late stage in the himalayan tibetan orogen shortening across two discrete thrust belts at 55 30 ma in southern and northern tibet created a large intracontinental basin the paleo qaidam basin in between subsequent crustal thickening and a possible thermal event in the mantle e g convective removal of central tibetan mantle lithosphere may have raised the elevation of this early intra plateau basin up to 2 3 km to its current height collision between india and asia also caused lateral extrusion of southeast asia between 32 ma and 17 ma the latest stage of the india asia collision was expressed by north trending rifting and the development of trench facing v shaped conjugate strike slip faults in central mongolia central tibet eastern afghanistan and southeast asia in the turkish iranian caucasus orogen early crustal thickening in the orogenic interior began at or prior to 30 20 ma this style of deformation was replaced by strike slip faulting at 15 5 ma associated with further northward penetration of arabia into asia westward extrusion of the anatolia turkey block and rapid extension across the sea of crete and sea of aegean the late stage extension in both orogens was locally related to extensional core complex development the continental margin extension of east asia was developed in two stages initially in a widely distributed zone that has an east west width of 500 800 km during 65 35 ma which was followed by localized extension and opening of back arc basins associated with the development of spreading centers at 32 17 ma e g japan sea or east korea sea bohai bay and south china sea opening of the back arc basins could be induced by 1 rapid eastward migration of the western pacific trench system or 2 oblique subduction of pacific plate beneath asia that had produced a series of en echelon right slip primary shear zones linking with back arc spreading centers oriented obliquely to the strike of the nearby trench since 15 ma the eastern margin of asia became contractional in the east west direction as indicated by the collapse of back arc basins in the western pacific and the development of fold thrust belts along the eastern continental margin coeval with the contraction is widespread east west extension in siberia north china and the tibetan plateau the above observations can be explained by a change in boundary condition along the eastern margin of asia that allowed the thickened asian continent to spread eastward causing east west extension in its trailing edge and east west compression in its leading edge in west asia continental margin extension started at about 25 20 ma in the aegean and cretan regions which was associated with a rapid southward retreat of the hellenic arc the complex evolution of cenozoic deformation in asia may be explained by a combined effect of temporal changes in plate boundary conditions thermal evolution of the upper mantle perturbed by collisional tectonics and the built up of gravitational energy through crustal thickening and thermal heating although the past research in asia has treated the india asia and arabia asia convergence as separate collisional processes their interaction may have controlled the far field cenozoic deformation in asia the most pronounced result of this interaction is the creation of a northeast trending 300 400 km wide and 1500 km long zone of northwest striking right slip faults which extends from the zagros thrust belt in the south to western mongolia in the north and links with the active tian shan and altai shan intracontinental orogens cenozoic deformation and coeval igneous activity spatially overlap with one another in the himalayan tibetan and turkish iranian caucasus orogens a large cenozoic magmatic gap exists between tibet in the south and mongolia in the north where cenozoic deformation has not been associated with any coeval igneous activity finally cenozoic igneous activity is always associated with jurassic cretaceous magmatic arcs suggesting a causal relationship between the early arc magmatism and later syn collisional magmatism

waveform inversion of broad band data of local earthquakes in the koyna warna region western india summary the koyna warna region in western india is the best example of reservoir triggered seismicity the world s largest triggered earthquake of magnitude 6 3 occurred in koyna in 1967 followed by several moderate to small earthquakes ever since a digital seismograph network deployed for seismic monitoring during 2005 august to 2008 december has indicated a shift in concentration of seismicity towards south in the warna region including a new zone of seismic activity to the southwest during the observation period 13 earthquakes of magnitude 4 and greater have occurred of which 11 occurred near the warna region while only two occurred in koyna in this study we modelled broad band waveform data of six of these earthquakes near warna using waveform inversion approach initially a new velocity model was determined using a joint hypocentral determination approach that simultaneously solves for the velocity structure as well as the hypocentral parameters a trap thickness of 1 2km with a p wave velocity of 4 40kms 1 and an upper crustal layer down to 10km with a velocity of 5 96kms 1 are obtained the new model not only provides the minimum residual error for the traveltimes but consistently provides the least mismatch error in the waveform inversion of all the events performing better than any of the previously determined velocity models in general focal mechanisms of normal type with ns to nnw sse oriented fault planes are obtained for all these events that are correlated with probable faults inferred from satellite images and aeromagnetic anomalies focal depths in the range of 5 6km are obtained for earthquakes in the warna region based on the sensitivity of whole waveform inversion at local distances it is felt that joint inversion of waveform data of several earthquakes with a wider spatial distribution along with the velocity structure would help in precisely characterizing the faulting mechanism and seismogenic depth range for the koyna warna region in future

neotectonic deformation in the transition zone between the dead sea transform and the east anatolian fault zone southern turkey a palaeomagnetic study of the karasu rift volcanism in southern turkey ongoing differential impingement of arabia into the weak anatolian collisional collage resulting from subduction of the neotethyan ocean has produced one of the most complex crustal interactions along the alpine himalayan orogen several major transforms with disputed motions including the northward extension of the dead sea fault zone dsfz meet in this region to evaluate neotectonic motion on the amanos and east hatay fault zones considered to be northward extensions of the dsfz the palaeomagnetism of volcanic fields in the karasu rift between these faults has been studied remanence carriers are low ti magnetites and all except 5 of 51 basalt lavas have normal polarity morphological polarity and k ar evidence show that rift formation occurred largely during the brunhes chron with volcanism concentrated at 0 66 0 35 ma and a subsidiary episode at 0 25 0 05 forty four units of normal polarity yield a mean of d i 8 8 54 7 with inclination identical to the present day field and declination rotated clockwise by 8 8 4 0 within the 15 km wide hassa sector of the karasu rift the volcanic activity is concentrated between the amanos and east hatay faults both with left lateral motions which have rotated blocks bounded by nw se cross faults in a clockwise sense as the arabian block has moved northwestwards an average lava age of 0 5 ma yields a minimum cumulative slip rate on the system bounding faults of 0 46 cm year according with the rate deduced from the africa arabia euler vector and reduced rates of slip on the southern extension of the dsfz during plio quaternary times estimates deduced from offsets of dated lavas flows and morphological features on the amanos fault zone tectonophysics 344 2002 207 are lower 0 09 0 18 cm year probably because they are limited to surface fault breaks and do not embrace the seismogenic crust results of this study suggest that most strike slip on the dsfz is taken up by the amanos east hatay afrin fault array in southern turkey comparable estimates of quaternary slip rate are identified on other faults meeting at an unstable fff junction dsfz east anatolian fault zone karatas fault zone a deceleration in slip rate across the dsfz and its northward continuation during plio quaternary times correlates with reorganization of the tectonic regime during the last 1 3 ma including tectonic escape within anatolia establishment of the north and east anatolian fault zones bounding the anatolian collage in mid late pliocene times a contemporaneous transition from transpression to transtension and concentration of all basaltic magmatism in this region within the last 1 ma

one dimensional velocity model station correction and earthquake relocation of local earthquakes in the koyna warna region india in this paper we investigated the feasibility of using the higher frequency waveforms to characterize the seismicity in the koyna warna region globally well known for its reservoir triggered earthquakes the local seismicity and source parameters have been extensively explored by many researchers using various types of data e g analog data broadband seismological data and deep seismic sounding data however here we have utilized the seismological data recorded by 97 temporary 4 5 hz geophones to locate the local seismicity in the region we first investigated an appropriate 1 d p wave velocity model through the inversion of p and s times in order to compensate for the thick and laterally heterogeneous basalt we incorporated the station corrections in the 1 d velocity inversion process the station correction varies from 0 09 to 0 20 s for the p waves with clear demarcations of positive and negative station corrections corresponding to the northern and southern regions respectively the patterns of positive and negative station corrections suggested that the northern part is characterized by lower velocity while slighter higher velocities present in the southern part of the study area are relative to the estimated 1 d velocity model the earthquake locations are further improved by using the double difference hypodd approach which enabled us to accurately map shallow subsurface seismogenic faults in the region the data comprises 10 062 p wave and 9049 s wave catalog differential times from 348 earthquakes 1 0 ml 4 5 the precisely relocated earthquakes erh 0 05 km erz 0 5 km and rms 0 02 s form the three clusters of earthquakes in the nw se direction along the lineaments close to warna reservoir the observed seismicity trends on the surface could be due to the vertical manifestations of faults or fractures their alignments are confirmed by the analysis of focal mechanism which exhibits a predominant normal type of faults with one nodal plane consistent with the main alignment of the seismic events

successive structural events in the hatay ophiolite of southeast turkey distinguishing oceanic emplacement and post emplacement phases of faulting abstract new structural data are presented and interpreted for the cretaceous hatay ophiolite which was emplaced onto the arabian continental margin during latest cretaceous maastrichtian time although lacking a preserved metamorphic sole a thick serpentinitic basal shear zone provides evidence of emplacement kinematics whilst structures developed in an extensive cenozoic sedimentary cover help to constrain the nature of post emplacement deformation combining field structural measurements with palaeostress analyses enables several discrete structural events to be recognised of which three appear to pre date the cenozoic sedimentary cover the earliest event involved extension parallel to the ophiolitic sheeted dyke complex and relates to oceanic spreading whereas the second and the third events relate to compression and strike slip during intra oceanic displacement or emplacement of the ophiolite onto the arabian continental margin some structures at the base of or within the ophiolite that were previously attributed to sea floor spreading processes e g oceanic detachment faults are more likely to have formed during subsequent ophiolite displacement emplacement and post emplacement formation of the regional hatay graben

the gulf of aden structure and evolution of a young ocean basin and continental margin new marine geophysical data are used to describe the structure and history of the gulf of aden magnetic anomaly data shows seafloor spreading magnetic anomalies of sheba ridge from the axial anomaly to anomaly 5 10 m y b p between the owen fracture zone and 45 sup 0 e and to anomaly 2 3 m y b p or anomaly 3 4 m y b p west of 45 sup 0 e the data does not support the two episodes of seafloor spreading recently proposed landward of the seafloor spreading magnetic anomalies is a magnetic quiet zone of uncorrelatable anomalies the magnetic quiet zone boundary is also a structural boundary effectively marking the edge of sheba ridge with deeper basement lacking a significant topographic gradient found on the landward side a magnetic quiet zone is found not only where sheba ridge splits continental lithosphere but also on east sheba ridge where the ridge splits the old oceanic lithosphre of the owen and somali basins there the position occupied by the continental margin within the gulf is marked by nonmagnetic ridge complexes that stretch from the continents to the owen fracture zone the magnetic quiet zone boundary is not an isochron in either the gulf of aden ormore the red sea suggesting that significant horizontal motions can occur prior to the initiation of seafloor spreading the offset on the dead sea rift is used to estimate that from 80 to 160 km of opening amounting to between 65 and 200 extension of the initial rift valley occurred in the gulf of aden and red sea prior to the establishment of a mid ocean ridge it is suggested that the development of a new ocean basin occurs in two stages the first involves diffuse extension over an area perhaps 10 km wide in a rift valley environment without an organized spreading center this is followed by concentration of the extension at a single axis and the beginning of true seafloor spreading less

the rotation of arabia and the levant fault system abstract we establish the kinematics of the rotation of arabia with respect to africa and show that the rotation rate of africa increased by a factor of about four in late serravallian time about 12 13 ma ago we discuss evidence that oceanic accretion started simultaneously in the gulf of aden and in the red sea at this time it is also at this time that the levant and anatolian fault systems were initiated our initial reconstruction of the red sea rift in late oligocene early miocene time approximately superposes the present shore lines which coincide with the mid point of the zones of rapid crustal thinning the future continental slopes the amount of extension during the early phase of continental rifting is obtained by assuming that the total volume of continental crust is conserved during extension and by checking these estimates through closure around the sinai triple junction in the late miocene the southern evant fault zone was a zone of distributed shear deformation through counterclockwise block rotation extending soul h ward within the northernmost red sea since the early pliocene the shear motion has been localized within the gulf of aqaba changing the tectonic pattern in the northern red sea

late cenozoic stress field in the cameli basin sw turkey a history of deformation has been determined for the cameli basin located in the western part of the major fethiye burdur fault zone interpreted as the on land continuation of pliny strabo fault system e g eastern boundary of the hellenic arc inversion of fault slip vectors affecting mio pliocene to quaternary formations in the cameli basin in the southwestern segment of the transtensional fethiye burdur fault zone yields two different normal faulting stress regimes characterized by a roughly orthogonal set of extensional axes a nw se n129 19 e 3 axis and a ne sw n50 16 e 3 axis the orientation of fault sets is predominantly around the ne sw direction in the major fethiye burdur fault zone making the extension nw se the mean r values are 0 74 and 0 69 for both extensions indicating a triaxial stress state which is clearly different from radial extension and from transitional to strike slip stress state the nw se extension is probably responsible for the formation of the cameli basin during mio pliocene time in contrast the inversion of focal mechanism solutions of shallow earthquakes occurring within the cameli basin identifies a present day predominantly extensional stress regime characterized by an approximately n s n184 e 3 axis which has an r value of 0 637 indicating a triaxial stress state the nearly orthogonal extensional stress regimes seem to have been acting contemporaneously with each other at different intensities from the mio pliocene onwards in sw turkey this may be attributed to the geodynamic effects related to the subduction of the african plate beneath anatolia diffusing along hellenic and cyprus arcs and in the west southwestward extrusion of anatolia our hypothesis is that the cause of the early nw se extension is the slab pull force due to the subduction process along the cyprus arc considered to be dominant up to plio quaternary the later ne sw to present day n s extension dominant since the plio quaternary is related to the combined forces of the anatolian extrusion and the subduction process along the hellenic arc

origin and interactions of fluids circulating over the amik basin hatay turkey and relationships with the hydrologic geologic and tectonic settings abstract we investigated the geochemical features of the fluids circulating over the amik basin se turkey syria border which is crossed by the northern extension of the dsf dead sea fault and represents the boundary area of three tectonic plates anatolian arabian and african plates we collected 34 water samples thermal and cold from natural springs and boreholes as well as 8 gas samples bubbling and gas seepage besides the gases dissolved in the sampled waters the results show that the dissolved gas phase is a mixture of shallow atmospheric and deep components either of mantle and crustal origin coherently the sampled waters are variable mixtures of shallow and deep ground waters the latter being characterised by higher salinity and longer residence times the deep groundwaters from boreholes deeper than 1000 m have a ch 4 dominated dissolved gas phase related to the presence of hydrocarbon reservoirs the very unique tectonic setting of the area includes the presence of an ophiolitic block outcropping in the westernmost area on the african plate as well as basalts located to the north and east on the arabic plate the diffuse presence of co 2 enriched gases although diluted by the huge groundwater circulation testifies a regional degassing activity fluids circulating over the ophiolitic block are marked by h 2 dominated gases with abiogenic methane and high ph waters the measured 3 he 4 he isotopic ratios display contributions from both crustal and mantle derived sources over both sides of the dsf although the serpentinization process is generally independent from mantle type contribution the recorded helium isotopic ratios highlight variable contents of mantle derived fluids due to the absence of recent volcanism over the western side of the basin african plate we argue that co 2 rich volatiles carrying mantle type helium and enriched in heavy carbon are degassed by deep rooted regional faults rather than from volcanic sources

le volcanisme quaternaire d anatolie centrale turquie association de magmatismes calco alcalin et alcalin en domaine de convergence collision volcanism in central anatolia cappadocia began at least in the late miocene because of the north south arabian eurasian convergence since this period the anatolian block is displaced towards the west along the north and east anatolian strike slip faults kinematic reconstructions show that the east anatolian fault is both sinistral and convergent as a consequence the anatolian block is currently being deformed quaternary volcanism in central anatolia is represented by several hundreds of monogenetic scoria cones lava flows maars and domes as well as two strato volcanoes hasan dag and erciyes dag the monogenetic volcanism is bimodal basalts and rhyolites whereas the stratovolcanoes exhibit a complete calc alkaline suite from basalts to rhyolites most of the igneous products are calc alkaline basalts erupted mainly from the monogenetic cones lava flows and maars andesites are encountered in the strato volcanoes as lava flows domes and nuees ardentes deposits dacites and rhy

3 d modeling of pore pressure diffusion beneath koyna and warna reservoirs western india the mechanism of reservoir triggered seismicity is well understood and explains the earthquake occurrence at different reservoir sites it can be attributed to the stresses due to water loading and to changes in fluid pressure in pores within the rock matrix in the present study a 3 d fluid flow numerical model is used to investigate the pore pressure diffusion as a cause for continued seismicity in the koyna warna region in western india it is shown that reservoir water level fluctuations are sufficient to trigger earthquakes at the seismogenic depths in the region our numerical model suggests that a vertical fault with hydraulic conductivity in the range 2 6 m day facilitates the diffusion of pressure at focal depths of earthquakes in the koyna warna region also for triggering of earthquakes a higher vertical conductivity is required for the warna region than for the koyna region a lag of two months period is found between the maximum water level and the significant hydraulic head required to trigger earthquakes at the focal depth using the appropriate hydraulic conductivity for both the reservoirs

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

moment tensor solutions and triggering environment for earthquakes in koyna warna water reservoirs region india we consider nine earthquakes in the koyna warna reservoir region on the western side of the peninsular india the deviatoric moment tensors of these earthquakes have been evaluated by minimizing the least squares misfit between observed and synthetic seismograms we use broadband seismograms of observatories at kard and pune which are at distances of nearly 50 and 150 km respectively from the epicenters both surface wave inversion and the difference between the arrival times of sh and sv show the presence of an anisotropic crust however we have obtained an equivalent isotropic structure by improving the published crustal structures of this area through inversion of surface wave group velocity data the deviatoric moment tensors of the earthquakes are decomposed into two components double couple and compensated linear vector dipoles clvd the double couple components of all the nine earthquakes show normal faulting with minor strike slip the t axis is consistently subhorizontal with an average azimuth of 260 6 and the p axis is nearly vertical the fault planes of six events give average strike direction and dip respectively as 194 0 and 51 8 and are associated with the main fault of the area the other three events lie in the southern part of this area and have strike direction between sse and se which is parallel to the tectonic features in this part the clvd component is generally within 20 percent of the total moment tensor recent studies show that anisotropy can produce source mechanism with clvd up to 30 percent and can also cause high pore fluid pressure leading to fault instability more rapidly compared to conventional mechanism in an isotropic medium it appears that the anisotropic crust noted in the present work is generating the clvd component and also gives the proper environment to trigger earthquakes by reservoirs through pore fluid pressure

modeling of the koyna india aftershock of 12 december 1967 short period teleseismic and near regional long period waveforms from a large aftershock mb 5 3 origin time 06 18 36 8 utc of the 10 december 1967 koyna main event were modeled to determine source depth and focal mechanism identification of pp and sp on the short period waveforms yielded a well constrained source depth of 3 5 to 4 0 km the focal mechanism was determined using a systematic trial and error grid testing technique in which seven p first motions two sh first motions two teleseismic pp p ratios one teleseismic sp p ratio and one regional sh p ratio were included this heterogeneous but sparse data set yielded a constrained normal fault mechanism at 100 20 strike 40 10 dip and 240 20 rake rupture directivity is inferred from consistently high surface reflection direct wave amplitude ratios a circular fault of 1 km radius with a rupture initiation point at the lower edge and an assumed rupture velocity of 0 9 vs explains the anomalously high amplitude ratios and yields a seismic moment of 3 8 1023 dyne cm the shallow source depth is similar to that found for the main event 4 5 km and the 13 september foreshocks 5 km in previous modeling studies and is consistent with the premise that the koyna earthquakes were triggered by the impoundment of the koyna reservoir however the normal fault mechanism differs substantially from the previous events which were left lateral strike slip faults trending nne the differing aftershock mechanism is probably due to the reactivation of old faults in the koyna area caused by stress readjustment after the koyna main event

late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates the arabia eurasia collision deforms an area of 3 000 000 km2 of continental crust making it one of the largest regions of convergent deformation on earth there are now estimates for the active slip rates total convergence and timing of collision related deformation of regions from western turkey to eastern iran this paper shows that extrapolating the present day slip rates of many active fault systems for 3 7 million years accounts for their total displacement this result means that the present kinematics of the arabia eurasia collision are unlikely be the same as at its start which was probably in the early miocene 16 23 ma or earlier in some but not all active fault systems short term 10 year and long term 5 million year average deformation rates are consistent there is little active thickening across the turkish iranian plateau and possibly the interior of the greater caucasus these are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening and where there are structural and or stratigraphic data for pre late miocene deformation we suggest that once thick crust up to 60 km built up in the turkish iranian plateau and the greater caucasus convergence took place more easily by crustal shortening in less elevated regions such as the zagros simple folded zone the south caspian region and foothills of the greater caucasus or in other ways such as westward transport of turkey between the north and east anatolian faults the time and duration of this changeover are not known for certain and are likely be diachronous although deformation started or intensified in many of the currently active fault systems at 5 2 ma

a braided strike slip model for the northern continuation of the dead sea fault and its implications for levantine tectonics abstract the assumption that the 100 110 km sinistral displacement on the dead sea fault is transmitted northwards along a single structure the yammouneh fault which runs ne sw across lebanon is here reviewed a number of valid objections to this concept exist a more attractive model supported by the limited data available from the area is that the motion is transmitted along a number of faults on this basis the temporary rightward flexure of the levant fracture through lebanon has given rise to a braided strike slip fault complex the yammouneh serrhaya fault system this model overcomes the objections against the older concept and allows the explanation of the mt lebanon bekaa valley anti lebanon complex in terms of transpressive and transtensive blocks a tentative outline of the cenozoic structural evolution of the area in terms of two or more phases of motion along the levant fracture is presented

tectonic history of the hatay ophiolites south turkey and their relation with the dead sea rift abstract the kizildag ophiolite massif lies in the hatay region of s turkey some structural relationships in the area are examined and two geological sections through the ophiolite are presented a sequence of structural events dealing with the emplacement and post emplacement history is established the significance of the events is discussed and it is suggested that the post emplacement structural history was dominated by movements along the dead sea rift

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

state of stress and tectonic evolution of the west spitsbergen fold belt abstract the west spitsbergen fold belt is the result of a e w to ene wsw oriented compression which affected the whole of spitsbergen a late cretaceous palaeocene age for the fold belt deformation is indicated by the involvement of only the basal tertiary conglomerates in the folding and thrusting in western spitsbergen this compressional event was followed by a strike slip stress pattern with nw se oriented extension and ne sw compression which generated micro structures within the tertiary rocks on the map scale normal faults produced by a ne sw oriented extension overprint the compressional structures the later strike slip and extensional stress patterns correspond to the svalbard greenland dextral motion along the de geer zone in latest palaeocene eocene time the latest tectonic event which affected the whole of svalbard was an e w oriented extension related to the spreading along the knipovich ridge in oligocene neogene time

the geology of mount hasan stratovolcano central anatolia turkey mount hasan is a double peaked stratovolcano located in central anatolia turkey the magmas erupted from this multi caldera complex range from basalt to rhyolite but are dominated by andesite and dacite two terminal cones big mt hasan and small mt hasan culminate at 3253 m and 3069 m respectively there are four evolutionary stages in the history of the volcanic complex stage 1 kecikalesi volcano 13 ma stage 2 palaeovolcano 7 ma stage 3 mesovolcano and stage 4 neovolcano the eruptive products consist of lava flows lava domes and pyroclastic rocks the later include ignimbrites phreatomagmatic intrusive breccias and nuees ardentes sometimes reworked as lahars the total volume is estimated to be 354 km 3 the area extent 760 km 2 textural and mineralogical data suggest that both magma mixing and fractional crystallization were involved in the generation of the andesites and dacites the magmas erupted from the central volcanoes show a transition with time from tholeite to calc alkaline three generations of basaltic strombolian cones and lava flows were emplaced contemporaneously with the central volcanoes the corresponding lavas are alkaline with a sodic tendency

earthquake recurrence parameters from seismic and geodetic strain rates in the eastern mediterranean summary although the parameters used in seismic hazard analyses imply a long term seismic strain rate they are usually not checked against such alternative estimates in this study we determine hazard parameters for the eastern mediterranean a value b value mmax and the corresponding long term seismic moment rate consistent with seismicity data tectonic information and geodetic strain rates the dense data coverage in this region permits a detailed comparison of the horizontal seismic strain rate field as recorded in the 500 yr long historical catalogue and the tectonic strain rate field measured geodetically we find that is very similar in style over all magnitude ranges within each different tectonic regime in the study region furthermore is similar in style to except along the hellenic arc is consistent with in amplitude we verify that for the high strain rates accommodated in the eastern mediterranean and historical catalogues spanning at least 100 200 yr should reflect the long term seismic strain release when averaged over each tectonic zone to estimate such seismic strain reliably accurate knowledge about the rates of recurrence of intermediate size events mw 4 5 6 5 is needed for b 1 these events can accommodate up to 60 per cent of the strain the combined analysis of and provides an estimate of the seismic total strain the major strike slip zones in the region the northern anatolian fault and the kephalonian fault experience little to negligible aseismic deformation in the remaining eastern mediterranean up to 10 30 per cent of the total deformation is aseismic the hellenic trench is largely uncoupled with at least 50 per cent and up to 90 per cent of the compressive strain released aseismically only the extensional component of strain at the eastern end of this trench appears significantly seismically active