fault interactions in the sea of marmara pull apart north anatolian fault earthquake clustering and propagating earthquake sequences summary knowledge on large earthquakes m 7 0 geology and fault kinematics is used to analyse conditions that favour isolated seismicity clustered earthquakes or propagating sequences along the north anatolian fault naf and the sea of marmara pull apart the overall naf marmara fault system is one of the most appropriate on earth to document fault interactions because reliable information covers almost completely two seismic cycles the past 500 yr coulomb stress analysis is used to characterize loading evolution in well identified fault segments including secular loading from below and lateral loading imposed by the occurrence of previous earthquakes earthquakes along the naf tend to occur where previous events have increased the stress but significant isolated events in the sea of marmara region 1894 1912 have occurred suggesting the secular loading has been the determining factor present day loading appears to be particularly high along the 70 km long segment located in the central marmara sea southwest of istanbul for the 18th century m 7 0 earthquake clusters we construct scenarios consistent with the tectonic and historical data we find that scenarios consistent with slip deficit and secular loading distributions from below clearly involve a sequence that propagates westward through the sea of marmara despite the structural complexity however the inference of a propagating sequence implies that each event has occurred in a segment previously stressed by lateral coulomb stress interactions the most likely scenarios for the propagating sequence are also consistent with coulomb stress interactions between faults with significant normal slip across the cinarcik basin propagating earthquake sequences do not occur every seismic cycle along the naf the loading has to be in a particular state of stress close to failure and uniform all along the fault segments to experience propagating earthquake sequences non uniform stress relief during the 18th century sequence explains the occurrence of isolated events in marmara in 1894 and 1912 as a consequence the wellknown 20th century sequence along the naf has not propagated as a sequence across the sea of marmara the most linear part of the naf across northern turkey behaves as a single fault segment accumulating stress during hundreds of years and rupturing entirely during very short periods the marmara pull apart fault system behaves as a major geometric complexity stopping or delaying the progression of earthquake clustering and propagating sequences fault zones interact with each other at a very large scale

implementing the effect of the rupture directivity on psha for the city of istanbul turkey abstract in the present study we improve the probabilistic seismic hazard assessment psha taking into account fault rupture related parameters that sensibly affect the azimuthal variability of the ground motion the study area is the marmara region turkey characterized by one of the highest levels of seismic risk in europe and the mediterranean region the seismic hazard in the city of istanbul is mainly associated with two active fault segments having well defined geometry focal mechanism and rate of activity deterministic dynamic models are also available in this area aochi and ulrich 2015 that aimed at evaluating the seismic potential of the marmara region these models provide the statistical distribution for the hypocenter position which is particularly relevant for rupture directivity the aim of this work is to incorporate all the available information about the seismic potential of the marmara region in a psha framework we use an analytical model for directivity spudich and chiou 2008 spudich et al 2013 to integrate rupture related parameters inside the psha standard procedure because the directivity effect is conditional on the hypocenter position which is not a priori known we assume at first ad hoc gaussian distributions centered in the western eastern or middle part of the two fault segments our results show that the correction for directivity introduces a significant contribution up to 25 of relative increase at 2 s to the hazard maps computed with the standard psha practice given in terms of pseudospectral accelerations having 10 probability of exceedance in 50 years the hazard maps sensibly change when we use the distribution for the hypocenter position informed by the statistical treatment of dynamic simulations thus integrating new variables in the psha in combination with properly informed probability density functions is not only feasible but also recommended for a comprehensive psha

successive aeolian saltation studies of idealized collisions as observed by bagnold and experimentally reconfirmed by other workers the impact angles of saltating grains are remarkably constant over a wide range of conditions lying between 10 and 16 it can be shown that successive saltation contains a mechanism which very effectively confines impact angles to that range this control mechanism is most effective at windspeeds less than about 15 30 m s 1 depending on grain diameter and mass the control mechanism is evaluated from model calculations of grain populations saltating over a level bed consisting of a layer of loose grains the grains are assumed to be spherical and uniform in size and mass also rigid and perfectly elastic the model also describes distributions of maximum height of grain paths and of lift off angles compared to other processes involved in aeolian saltation successive saltation is the only process with a high probability of transferring energy from horizontal into vertical grain movement this fact together with the calculations presented strongly suggests that successive saltation plays a major role in saltation in air successive saltation of uniform grains is theoretically impossible if the ground over which saltation occurs is tilted by about 15 against wind direction values of tilt angles in this range are observed in nature as stoss side angles of dunes and ripples leading to the concept that stoss sides are tilted up by deposition until successive saltation is subdued

seismic imaging of the three dimensional architecture of the cinarcik basin along the north anatolian fault the cinarcik basin is a transtensional basin located along the northern branch of the northern north anatolian fault naf in the sea of marmara the eastern half of which has been identified as a seismic gap during the seismarmara 2001 experiment a dense grid of multichannel seismic reflection profiles was shot covering the whole cinarcik basin and its margins the new seismic images provide a nearly three dimensional view of the architecture of the basin fault system at depth and sedimentary infill and provide insight into its tectonic evolution along both northern and southern margins of the basin seismic reflection data show deep penetrating faults hence long lived features which have accommodated a large amount of extension there is no indication in the data for a single throughgoing strike slip fault neither a cross basin fault nor a pure strike slip fault running along the northern margin faster opening is presently observed in the eastern part of the basin the cinarcik basin seems to have developed as a transtensional basin across strike slip segments of the northern naf for the last few million years

structure and paleoearthquake records of active submarine faults cook strait new zealand implications for fault interactions stress loading and seismic hazard 1 a new interpretation of active faulting in central cook strait new zealand reveals tectonic structures associated with the spatial transition from subduction to continental transform faulting marine seismic reflection profiles and multibeam bathymetric data indicate that there are no throughgoing crustal faults connecting the north island dextral fault belt and the marlborough fault system in south island the major faults terminate offshore associated with 5 20 km wide step overs and a change in regional fault strike this structure implies that propagation of strike slip earthquake ruptures across the strait is not probable faulted sedimentary sequences in the wairau basin marlborough shelf correlated to glacioeustatic sea level cycles provide a stratigraphic framework for fault analysis a high resolution study of the postglacial 20 ka vertical displacement history of the cloudy and vernon faults reveals up to six and five paleoearthquakes since 18 ka respectively these long timescale records indicate variable recurrence intervals and possibly variable stress drop thus conforming to the variable slip model of earthquake behavior integration of these data with other submarine and terrestrial paleoearthquake records indicates the presence of clustered earthquake sequences involving multiple faults different sequences do not always involve the same faults it appears that earthquake clustering is driven by fault interactions that lead to specific loading conditions favoring the triggering of earthquakes on major faults in relatively short time intervals present day regional coulomb stress distribution has been calculated in two scenarios considered to represent minimum and maximum loading conditions the models incorporating secular tectonic loading and stress changes associated with major crustal earthquakes indicate high stress loading in a large part of central cook strait these conditions may favor the triggering of future damaging earthquakes in this region

long term seismicity of istanbul and of the marmara sea region we examine the long term seismicity of the marmara sea region in turkey over a period of twenty centuries to attempt to answer two questions 1 how well recorded in history is the earthquake activity of this region and 2 does seismicity over this long period of time differ from that over the present century we study this densely populated and fast developing region because it is one of the most tectonically active regions on the continents that appears today to be relatively quiescent

geological evidence for the last two faulting events on the north anatolian fault zone in the mudurnu valley western turkey abstract recurrence intervals of large earthquakes produced by slip on the north anatolian fault zone have been inferred mainly from historical records and included much ambiguity it is therefore important to date individual earthquakes using geological and geomorphological methods we excavated an exploratory trench across the surface rupture zone associated with the mudurnu valley western turkey earthquake of july 22 1967 and revealed evidence for the last two faulting events including the 1967 earthquake on the basis of the radiocarbon dates of sediments in the trench we estimate most conservatively that the penultimate event occurred after 1480 a d but believe it likely that the event occurred shortly after 1650 20 a d the penultimate event is likely to be correlated with the anatolian earthquake of august 17 1668 which caused severe damage along the north anatolian fault zone for about 600 km from bolu to erzincan

distribution of seismic velocities and attenuation in the crust beneath the north anatolian fault turkey from local earthquake tomography we investigate the crustal structure beneath the western part of the north anatolian fault zone nafz an area where at least five damaging earthquakes occurred during the twentieth century this study is based on local earthquake tomography using the data from aftershocks of the izmit event 17 august 1999 m 7 4 recorded by stations of permanent and temporary networks we derive the distribution of v p v s and the v p v s ratio based on the iterative inversion for both v p v s and v p v p v s using the lotos code innovatively in this study we perform an inversion for frequency dependent s wave attenuation 1 q s the reliability of the results is assessed through synthetic tests the distributions of the resulting seismic parameters v p v s v p v s and q s highlight important geodynamical features in the study area the low velocity and high attenuation patterns mostly correlate with the fracturing zones of the nafz low velocities are also observed beneath the main sedimentary basins e g adapazari duzce and kuzuluk high velocity and low attenuation patterns correlate with blocks presumed to be rigid kocaeli armutlu and almacik blocks the rupture traces of the largest earthquakes in this area pass generally in the transition areas between high and low velocities while moderate and weak seismicity is mostly concentrated in low velocity areas based on these results we propose and discuss the role that the almacik block could have played in producing the largest earthquakes in the study area in the twentieth century

heightened odds of large earthquakes near istanbul an interaction based probability calculation we calculate the probability of strong shaking in istanbul an urban center of 10 million people from the description of earthquakes on the north anatolian fault system in the marmara sea during the past 500 years and test the resulting catalog against the frequency of damage in istanbul during the preceding millennium departing from current practice we include the time dependent effect of stress transferred by the 1999 moment magnitude m 7 4 izmit earthquake to faults nearer to istanbul we find a 62 15 probability one standard deviation of strong shaking during the next 30 years and 32 12 during the next decade

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

the surface rupture and slip distribution of the 17 august 1999 izmit earthquake m 7 4 north anatolian fault the 17 august 1999 izmit earthquake occurred on the northern strand of the north anatolian fault zone the earthquake is associated with a 145 km long surface rupture that extends from southwest of duzce in the east to west of hersek delta in the west detailed mapping of the surface rupture shows that it consists of five segments separated by releasing step overs herein named the hersek karamursel golcuk izmit sapanca lake sapanca akyazi and karadere segments from west to east respectively the hersek segment which cuts the tip of a large delta plain in the western end of the rupture zone has an orientation of n80 the n70 80 e trending karamursel golcuk segment extends along the linear southern coasts of the izmit gulf between karamursel and golcuk and produced the 470 cm maximum displacement in golcuk the northwest southeast striking golcuk normal fault between the karamursel golcuk and izmit sapanca segments has 2 3 m maximum vertical displacement the maximum dextral offset along the izmit sapanca lake segment was measured to be about 3 5 m and its trend varies between n80 e and east west the sapanca akyazi segment trends n75 85 w and expresses a maximum displacement of 5 2 m the karadere segment trends n65 e and produced up to 1 5 m maximum displacement the karadere and sapanca akyazi segments form fan shape or splaying ruptures near their eastern ends where the displacement also diminished

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

an alternative view of the microseismicity along the western main marmara faultan alternative view of the microseismicity along the western main marmara fault

the active main marmara fault abstract this paper presents selections from and a synthesis of a high resolution bathymetric sparker and deep towed seismic reflection data set recently acquired by the french ifremer r v le suroit in an e w deep trough that forms the northern half of the sea of marmara in nw turkey it includes the first high resolution complete bathymetric map of this area a single throughgoing dextral strike slip fault system which is the western continuation of the northern branch of the north anatolian fault cuts this trough lengthwise and joins the 1999 8 17 kocaeli earthquake fault with the 1912 8 09 arkoy murefte earthquake fault both of which display strike slip offset in its eastern one fourth the structure follows closely the northern margin of the deep trough whereas in the west it hugs its southern margin the eastern one fourth of the structure has a minor component of its displacement distributed across the deep trough owing to a possible original bend in the course of the dextral structure the present course of the north anatolian fault in the sea of marmara originated some 2 105 a ago by cutting across the older basin fabric generated by a dominant nne ssw extension before it began taking up major motion in the pliocene

a relict paleoseismic record of seven earthquakes between 2000 b c and 600 a d on the central north anatolian fault at elmacik near osmancik turkey deformation along the northern edge of the westward moving anatolian plate is concentrated along the north anatolian fault this northward arching fault extends from the karliova triple junction in the east 1500 km into the aegean sea in the west a sequence of twentieth century earthquakes ruptured the fault displaying a spatiotemporal pattern consistent with a stress triggering mechanism in 1943 the m w 7 6 tosya earthquake ruptured a 280 km long segment near the center of the fault four paleoseismic investigations have previously investigated this segment and the present study was conducted near its center in an 180 km long gap between existing studies a paleoseismic trench revealed a sequence of eight sediment packages abutting a highly developed shear zone each of the packages consists of a fine grained layer overlying a coarse grained layer based on correlation between the age of the base of the coarse grained layers and existing earthquake records we infer that the coarse grained layers were deposited in response to earthquakes because of increased erosion on an adjacent steep slope the most recent event horizon may correlate to the historical 529 a d earthquake timing of six older earthquakes is constrained to 2s 23 b c 103 a d 609 185 b c 971 814 b c 1227 968 b c 2050 1777 b c and 2556 2235 b c which correspond to a summed interevent time of 97 912 yr 2s the earthquake record is relict because the local stream network was incised ca 1000 a d isolating the trench site from its sediment source a stream near the trench was subsequently offset by 23 5 1 5 m yielding a right lateral slip rate of 21 4 25 6 mm yr and suggesting that the 1943 rupture caused an uncharacteristically small offset

seismotectonics of the armutlu peninsula marmara sea nw turkey from geological field observation and regional moment tensor inversion abstract the armutlu peninsula located in the eastern marmara sea coincides with the western end of the rupture of the 17 august 1999 izmit mw 7 6 earthquake which is the penultimate event of an apparently westward migrating series of strong and disastrous earthquakes along the nafz during the past century we present new seismotectonic data of this key region in order to evaluate previous seismotectonic models and their implications for seismic hazard assessment in the eastern marmara sea long term kinematics were investigated by performing paleo strain reconstruction from geological field investigations by morphotectonic and kinematic analysis of exposed brittle faults short term kinematics were investigated by inverting for the moment tensor of 13 small to moderate recent earthquakes using surface wave amplitude spectra our results confirm previous models interpreting the eastern marmara sea region as an active transtensional pull apart environment associated with significant nne ssw extension and vertical displacement at the northern peninsula long term deformation pattern did not change significantly since pliocene times contradicting regional tectonic models which postulate a newly formed single dextral strike slip fault in the marmara sea region this area is interpreted as a horsetail splay fault structure associated with a major normal fault segment that we call the waterfall fault apart from the waterfall fault the stress strain relation appears complex associated with a complicated internal fault geometry strain partitioning and reactivation of pre existing plane structures at the southern peninsula recent deformation indicates active pull apart tectonics constituted by ne sw trending dextral strike slip faults earthquakes generated by stress release along large rupture zones seem to be less probable at the northern but more probable at the southern peninsula additionally regional seismicity appears predominantly driven by plate boundary stresses as transtensional faulting is consistent with the southwest directed far field deformation of the anatolian plate

dynamic triggering of earthquakes is promoted by crustal heterogeneities and bimaterial faults remotely triggered earthquakes and aftershocks constitute a great challenge in assessing seismic risk a growing body of observations indicates that significant earthquakes can be triggered by moderate to great earthquakes occurring at distances of up to thousands of kilometres currently we lack the knowledge to predict the location of triggered events we present numerical simulations showing that dynamic interactions between material heterogeneities e g compliant fault zones sedimentary basins and seismic waves focus and enhance stresses sufficiently to remotely trigger earthquakes numerical simulations indicate that even at great distances 100 km the amplified transient dynamic stress near heterogeneities is equivalent to stress levels near the source rupture tip 5 km such stress levels are widely considered capable of nucleating an earthquake rupture on a pre stressed fault analysis of stress patterns in dynamic rupture simulations which include a heterogeneous zone with a range of material and geometrical properties reveals various mechanisms of stress enhancement we conclude that both stiff and weak heterogeneities may focus stress waves to form zones of enhanced stress and that bimaterial interfaces distort under static and dynamic loading in a way that induces local stress concentrations our work provides insights for understanding non uniform distribution of remotely triggered seismicity and recurrence of such events along complex fault systems and near magmatic intrusions and geothermal zones

abrupt cooling of antarctic surface waters and sea ice expansion in the south atlantic sector of the southern ocean at 5000 cal yr b p antarctic surface waters were warm and ice free between 10 000 and 5000 cal yr b p as judged from ice rafted debris and microfossils in a piston core at 53 s in the south atlantic this evidence shows that about 5000 cal yr b p sea surface temperatures cooled sea ice advanced and the delivery of ice rafted detritus ird to the subantarctic south atlantic increased abruptly these changes mark the end of the hypsithermal and onset of neoglacial conditions they coincide with an early neoglacial advance of mountain glaciers in south america and new zealand between 5400 and 4900 cal yr b p rapid middle holocene climate changes inferred from the taylor dome ice core antarctica cooling and increased ird in the north atlantic and the end of the african humid period the near synchrony and abruptness of all these climate changes suggest links among the tropics and both poles that involved nonlinear response to gradual changes in northern hemisphere insolation sea ice expansion in the southern ocean may have provided positive feedback that hastened the end of the hypsithermal and african humid periods in the middle holocene

no significant steady state surface creep along the north anatolian fault offshore istanbul results of 6 months of seafloor acoustic ranging the submarine istanbul silivri fault segment within 15km of istanbul is the only portion of the north anatolian fault that has not ruptured in the last 250years we report first results of a seafloor acoustic ranging experiment to quantify current horizontal deformation along this segment and assess whether the segment is creeping aseismically or accumulating stress to be released in a future event ten transponders were installed to monitor length variations along 15 baselines a joint least squares inversion for across fault baseline changes accounting for sound speed drift at each transponder precludes fault displacement rates larger than a few millimeters per year during the 6month observation period forward modeling shows that the data better fit a locked state or a very moderate surface creep less than 6mm yr compared to a far field slip rate of over 20mm yr suggesting that the fault segment is currently accumulating stress

slip partitioning in the sea of marmara pull apart determined from gps velocity vectors summary dislocation modelling is used to examine the gps velocity vectors for the marmara sea region first the vectors due to the known anatolia eurasia rotation are reproduced by introducing structures that approximate the large scale tectonics observed features of the smaller scale fault system in the marmara region are then progressively included with slip amplitudes and directions adjusted to fit an 80 vector subset of the gps data the motion in the marmara sea region is partitioned with the faults that bound the north of the basin carrying more strike slip motion than predicted from the anatolia eurasia plate motion and faults to the south having a greater perpendicular component taken together however there is no net opening across the marmara sea perpendicular to the overall trend of the boundary and thus deformation in the marmara region results only from the pull apart geometry of the north anatolian fault no extension related to the aegean system is needed to explain the observations the gps results are consistent with motion over the last 5 myr that has been determined from geological reconstructions

seismic hazard in the marmara sea region following the 17 august 1999 izmit earthquake on 17 august 1999 a destructive magnitude 7 4 earthquake occurred 100 km east of istanbul near the city of izmit on the north anatolian fault this 1 600 km long plate boundary 1 2 slips at an average rate of 2 3 cm yr 1 refs 3 5 and historically has been the site of many devastating earthquakes 6 7 this century alone it has ruptured over 900 km of its length 6 models of earthquake induced stress change 8 combined with active fault maps 9 had been used to forecast that the epicentral area of the 1999 izmit event was indeed a likely location for the occurrence of a large earthquake 9 10 here we show that the 1999 event itself significantly modifies the stress distribution resulting from previous fault interactions 9 10 our new stress models take into account all events in the region with magnitudes greater than 6 having occurred since 1700 ref 7 as well as secular interseismic stress change constrained by gps data 11 these models provide a consistent picture of the long term spatio temporal behaviour of the north anatolian fault and indicate that two events of magnitude equal to or greater than the izmit earthquake are likely to occur within the next decades beneath the marmara sea south of istanbul

the mechanical interaction between the propagating north anatolian fault and the back arc extension in the aegean we use fracture mechanics concepts to analyse the large scale deformation of anatolia and the aegean our purpose is to characterize the process of propagation of the north anatolian fault naf our approach incorporates long term geological constraints in dislocation modelling of present day gps velocities that allows for internal deformation in regions between major structures unravelling the superposition of two deformation fields now interacting in the aegean propagating naf and back arc extension permits us to characterise the large scale damage zone at the western end of the naf and to determine slip rates for the main structures the contemporary slip rate profile of the naf shows that it apparently behaves like a transform fault for 75 of its length the process zone corresponds to a rapid southwestward tapering of the naf slip rate modelling slip rate distributions for the naf under stress free conditions shows that the development of the process zone depends on the boundary conditions imposed at the hellenic arc our stress free modelling suggests a scenario for the evolution of the naf 1 at an earlier stage before the naf had reached the aegean it was not under the influence of hellenic arc pull its slip rate profile is modelled to have a half elliptical shape corresponding to a crack in elastic solid and an elastically strained anatolian lithosphere 2 the present day naf penetrates the aegean and a large process zone has developed due to interaction with the aegean extension and the hellenic arc pull elastic strains in the anatolian lithosphere are relaxed and the naf resembles a transform fault the models that we present suggest that changes in subduction zone behaviour should influence all of the boundaries associated with anatolian extrusion

possible worst case tsunami scenarios around the marmara sea from combined earthquake and landslide sources this study evaluates tsunami hazards in the marmara sea from possible worst case tsunami scenarios that are from submarine earthquakes and landslides in terms of fault generated tsunamis seismic ruptures can propagate along the north anatolian fault naf which has produced historical tsunamis in the marmara sea based on the past studies which consider fault generated tsunamis and landslide generated tsunamis individually future scenarios are expected to generate tsunamis and submarine landslides could be triggered by seismic motion in addition to these past studies numerical modeling has been applied to tsunami generation and propagation from combined earthquake and landslide sources in this study tsunami hazards are evaluated from both individual and combined cases of submarine earthquakes and landslides through numerical tsunami simulations with a grid size of 90 m for bathymetry and topography data for the entire marmara sea region and validated with historical observations from the 1509 and 1894 earthquakes this study implements tunami model with a two layer model to conduct numerical tsunami simulations and the numerical results show that the maximum tsunami height could reach 4 0 m along istanbul shores for a full submarine rupture of the naf with a fault slip of 5 0 m in the eastern and western basins of the marmara sea the maximum tsunami height for landslide generated tsunamis from small medium and large of initial landslide volumes 0 15 0 6 and 1 5 km3 respectively could reach 3 5 6 0 and 8 0 m respectively along istanbul shores possible tsunamis from submarine landslides could be significantly higher than those from earthquakes depending on the landslide volume significantly these combined earthquake and landslide sources only result in higher tsunami amplitudes for small volumes significantly because of amplification within the same tsunami amplitude scale 3 0 4 0 m waveforms from all the coasts around the marmara sea indicate that other residential areas might have had a high risk of tsunami hazards from submarine landslides which can generate higher tsunami amplitudes and shorter arrival times compared to istanbul

submarine fault scarps in the sea of marmara pull apart north anatolian fault implications for seismic hazard in istanbul earthquake scarps associated with recent historical events have been found on the floor of the sea of marmara along the north anatolian fault naf the marmarascarps cruise using an unmanned submersible rov provides direct observations to study the fine scale morphology and geology of those scarps their distribution and geometry the observations are consistent with the diversity of fault mechanisms and the fault segmentation within the north marmara extensional step over between the strike slip ganos and izmit faults smaller strike slip segments and pull apart basins alternate within the main step over commonly combining strike slip and extension rapid sedimentation rates of 1 3 mm yr appear to compete with normal faulting components of up to 6 mm yr at the pull apart margins in spite of the fast sedimentation rates the submarine scarps are preserved and accumulate relief sets of youthful earthquake scarps extend offshore from the ganos and izmit faults on land into the sea of marmara our observations suggest that they correspond to the submarine ruptures of the 1999 izmit mw 7 4 and the 1912 ganos ms 7 4 earthquakes while the 1999 rupture ends at the immediate eastern entrance of the extensional cinarcik basin the 1912 rupture appears to have crossed the ganos restraining bend into the sea of marmara floor for 60 km with a right lateral slip of 5 m ending in the central basin step over from the gulf of saros to marmara the total 1912 rupture length is probably about 140 km not 50 km as previously thought the direct observations of submarine scarps in marmara are critical to defining barriers that have arrested past earthquakes as well as defining a possible segmentation of the contemporary state of loading incorporating the submarine scarp evidence modifies substantially our understanding of the current state of loading along the naf next to istanbul coulomb stress modeling shows a zone of maximum loading with at least 4 5 m of slip deficit encompassing the strike slip segment 70 km long between the cinarcik and central basins that segment alone would be capable of generating a large magnitude earthquake mw 7 2 other segments in marmara appear less loaded

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

recalculated probability of m 7 earthquakes beneath the sea of marmara turkey 1 new earthquake probability calculations are made for the sea of marmara region and the city of istanbul providing a revised forecast and an evaluation of time dependent interaction techniques calculations incorporate newly obtained bathymetric images of the north anatolian fault beneath the sea of marmara le pichon et al 2001 armijo et al 2002 newly interpreted fault segmentation enables an improved regional a d 1500 2000 earthquake catalog and interevent model which form the basis for time dependent probability estimates calculations presented here also employ detailed models of coseismic and postseismic slip associated with the 17 august 1999 m 7 4 izmit earthquake to investigate effects of stress transfer on seismic hazard probability changes caused by the 1999 shock depend on marmara sea fault stressing rates which are calculated with a new finite element model the combined 2004 2034 regional poisson probability of m 7 earthquakes is 38 the regional time dependent probability is 44 18 and incorporation of stress transfer raises it to 53 18 the most important effect of adding time dependence and stress transfer to the calculations is an increase in the 30 year probability of a m 7 earthquake affecting istanbul the 30 year poisson probability at istanbul is 21 and the addition of time dependence and stress transfer raises it to 41 14 the ranges given on probability values are sensitivities of the calculations to input parameters determined by monte carlo analysis 1000 calculations are made using parameters drawn at random from distributions sensitivities are large relative to mean probability values and enhancements caused by stress transfer reflecting a poor understanding of large earthquake aperiodicity index terms 7223 seismology seismic hazard assessment and prediction 7230 seismology seismicity and seismotectonics 8150 tectonophysics plate boundary general 3040 keywords earthquake probability sea of marmara seismic hazard turkey stress interaction north anatolian fault

anatomy of a buried thrust belt activated during hydraulic fracturing abstract tectonically active fault networks are often inter connected but in the case of injection induced seismicity prior knowledge of fault architecture tends to be severely limited in most cases reactivated faults due to fluid injection are inferred after the fact by the spatial distribution of induced seismicity hypocenters such reliance on post injection seismicity impedes any pre operational risk analysis as well as development of a more holistic understanding of fault system models by combining high resolution depth migrated 3 d seismic data with a new focal depth estimation method that reduces spatial uncertainty of hypocenters this study pinpoints microearthquake fault activation within a buried thrust belt in the montney formation in western canada british columbia during hydraulic fracturing operations rupture nucleation occurred on seismically imaged thrust ramps that cut through the debolt formation a massive carbonate layer that underlies the stimulated zone high resolution seismic images reveal transverse structures interpreted as basement controlled fold hinges or tear faults that transferred displacement between thrust faults during late cretaceous paleogene compressional shortening the spatio temporal pattern of induced seismicity suggests that these transverse structures provide permeable pathways for aseismic pore pressure diffusion thus connecting distinct thrust faults and enabling earthquake triggering on a timescale of days and at distances of up to 2 km from the injection wells inferred relationships highlight how the fault system is connected including apparent stress concentrations at the intersections of transverse structures and orogen parallel thrust ramps

the north anatolian fault in the sea of marmara 1 using the detailed geometry and tectonics of the main marmara fault that connects the gulf of izmit fault with the ganos fault established by le pichon et al 2001 and the new gps data set recently analyzed by meade et al 2002 we confirm the existence of a marmara block delimited to the north by the northern branch of the north anatolian fault the marmara branch and to the south by the southern branch the kinematics of this block indicate that the marmara branch that crosses the sea of marmara is close to pure dextral strike slip at a rate of 23 mm yr on its whole length the short cinarcik section is the only one where a significant extensional component is predicted a simple kinematic model accounts for slip partitioning there with 8 10 mm yr of extension to the south of the basin and 23 mm yr of dextral strike slip along the northern cinarcik margin the new gps data demonstrate the existence of important asymmetric elastic loading along the main marmara fault that may have significant implications for the seismotectonics of the area the expected future large earthquake may rupture the whole main marmara fault the partitioning in the cinarcik basin may produce magnitude 7 normal faulting earthquakes if their repetition time is about 250 years the 1896 earthquake may have been one of these normal fault earthquakes the marmara block is less than 1 ma prior to its formation it was part of the anatolian block at this time the ganos fault was already a dextral strike slip fault but the fault system in the sea of marmara would have been affected by an extensional component increasing toward the east that accounts for the increasing size of the sedimentary basins eastward

modelling tectonic deformation along the north anatolian fault in the sea of marmara abstract using analogue techniques we attempted to model the complex tectonic deformation pattern observed along the north anatolian fault in the sea of marmara from morpho bathymetry and seismic reflection images in particular this paper focuses on the so called cinarcik segment of the fault connecting the eastern izmit segment which entirely ruptured during the mw 7 4 1999 earthquake to the western segment of the central high the cinarcik segment potentially loaded after the izmit earthquake is expected to rupture during an earthquake occurring in the near future possibly the next decades with a high potential to affect the istanbul metropolitan area our analysis suggests that the development of the observed structures accommodating strike slip transtensional and transpressional deformations could be explained by changes in the geometry of fault segments within a right lateral strike slip tectonic regime tectonic deformations were reproduced in the analogue model by imposing a small about 10 and sharp difference in the relative orientations of the strike slip segments at the edges of a major releasing bend in the model slower strain accumulation occurs along the analogue of the cinarcik segment than along the analogue of the izmit segment of the fault this would predict a delay for earthquakes triggered by stress transfer between the izmit and cinarcik segments the model further predicts that most of the deformation in the cinarcik basin is controlled by the sharp changes in the geometry of the fault itself

westward propagation of the north anatolian fault into the northern aegean timing and kinematics we present new evidence for the propagation processes of the north anatolian fault folding in the dardanelles straits region allows us to document the timing of the deformation preceding and the finite displacement after the passage of the propagating tip of the fault the accuracy of the observations is due to interplay between deformation and the sea level changes in the mediterranean the well known messinian regression followed by the pliocene transgression the long term kinematics around the sea of marmara pull apart total displacement of about 85 km over the past 5 m y is similar to the present day kinematics deduced from space geodesy at a larger scale westward propagation of the north anatolian fault over nearly 2000 km in the past 10 m y appears to be associated with strain recovery suggesting that the continental lithosphere retains long term elasticity

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

asymmetric slip partitioning in the sea of marmara pull apart a clue to propagation processes of the north anatolian fault between 1939 and 1999 the north anatolian fault naf experienced a westward progression of eight large earthquakes over 800 km of its morphological trace the 2000 km long north anatolian transform fault has also grown by westward propagation through continental lithosphere over a much longer timescale 10 myr the sea of marmara is a large pull apart that appears to have been a geometrical mechanical obstacle encountered by the naf during its propagation the present paper focuses on new high resolution data on the submarine fault system that forms a smaller pull apart beneath the northern sea of marmara between two well known strike slip faults on land izmit and ganos faults the outstandingly clear submarine morphology reveals a segmented fault system including pull apart features at a range of scales which indicate a dominant transtensional tectonic regime there is no evidence for a single continuous purely strike slip fault this result is critical to understanding of the seismic behaviour of this region of the naf close to istanbul additionally morphological and geological evidence is found for a stable kinematics consistent both with the long term displacement field determined for the past 5 myr and with present day anatolia eurasia motion determined with gps however within the sea of marmara region the fault kinematics involves asymmetric slip partitioning that appears to have extended throughout the evolution of the pull apart the loading associated with the westward propagation process of the naf may have provided a favourable initial geometry for such a slip separation

geomechanical model of the marmara sea region i 3 d contemporary kinematics summary we investigate by means of a 3 d geomechanical model the relationship between structural elements and contemporary kinematics in the marmara sea region northwest turkey the recently imaged fault system beneath the marmara sea is incorporated into the model as frictional surfaces with varying strike and dip the main marmara fault is implemented as through going and is accompanied by mostly non vertical second order faults topography basement topography and the moho become mechanically effective through changes in density and elastic parameters across these horizons the model is subjected to gravity and kinematic boundary conditions the ultimate goal of this study is to set up a 3 d model that is consistent with both kinematic observations and stress data the stress results are presented in a complementary paper in this paper we present the modelled long term 3 d kinematics in terms of fault slip rates rotations vertical motion and sense of fault slip the model results agree with global positioning system velocities geological fault slip rates palaeomagnetic measurements and with the observed pattern of subsidence and uplift furthermore our tectonically driven vertical velocities can be linked to landscape and basin evolution and to features of sedimentation our results indicate that the main marmara fault can be interpreted as a through going fault that slips almost purely in a strike slip sense nevertheless and not contradictory to the previous statement there is significant dip slip motion at some sections of the main marmara fault the agreement of the modelled 3 d kinematics with model independent observations supports that the main structural details of the fault system are accounted for sensitivity analysis of model parameters reveals that changes in rock properties and the initial stress state have minor influence on the 3 d kinematics we conclude that the 3 d structure of the fault system is the key control of the kinematics the slip rate of the main marmara fault from our model is lower than previous estimates and shows high variability along strike 12 8 17 8 mm a 1 the latter indicates that stress accumulation is non uniform along strike

m 7 earthquake rupture forecast and time dependent probability for the sea of marmara region turkey we forecast time independent and time dependent earthquake ruptures in the marmara region of turkey for the next 30 years using a new fault segmentation model we also augment time dependent brownian passage time bpt probability with static coulomb stress changes cff from interacting faults we calculate mw 6 5 probability from 26 individual fault sources in the marmara region we also consider a multisegment rupture model that allows higher magnitude ruptures over some segments of the northern branch of the north anatolian fault zone beneath the marmara sea a total of 10 different mw 7 0 to mw 8 0 multisegment ruptures are combined with the other regional faults at rates that balance the overall moment accumulation we use gaussian random distributions to treat parameter uncertainties e g aperiodicity maximum expected magnitude slip rate and consequently mean recurrence time of the statistical distributions associated with each fault source we then estimate uncertainties of the 30 year probability values for the next characteristic event obtained from three different models poisson bpt and bpt cff using a monte carlo procedure the gerede fault segment located at the eastern end of the marmara region shows the highest 30 year probability with a poisson value of 29 and a time dependent interaction probability of 48 we find an aggregated 30 year poisson probability of m 7 3 earthquakes at istanbul of 35 which increases to 47 if time dependence and stress transfer are considered we calculate a twofold probability gain ratio time dependent to time independent on the southern strands of the north anatolian fault zone

stress coupling between earthquakes in northwest turkey and the north aegean sea we have investigated the coulomb stress interactions of 29 earthquakes m s greater than or equal to 6 0 that have occurred in the region of northwest turkey and north aegean sea since 1912 of these events 23 may be related to earlier events and 16 are clearly related to earlier events all events after 1967 are related to previous events events in the early part of our time interval that show no correlation could be related to historical events as yet unidentified in some cases faults that have received a stress reduction from earlier events are prepared for an event by an earthquake occurring a few years before that creates a local coulomb stress rise thus regions of coulomb stress shadow can become regions where a damaging earthquake may occur the relation between smaller events and the coulomb stress distribution is less clear but may be related to poor data quality and practical limitations of our modeling technique nonetheless there are 4 times as many events per unit area in regions of enhanced stress than where stress is reduced we discuss the contemporary distribution of coulomb stress and argue that it is possible to identify the likely locations of future damaging earthquakes including identifying the most likely candidate faults

paleoseismic evidence of characteristic slip on the western segment of the north anatolian fault turkey we have conducted a paleoseismic investigation of serial fault rupture at one site along the 110 km rupture of the north anatolian fault that produced the mw 7 4 earthquake of 17 august 1999 the benefit of using a recent rupture to compare serial ruptures lies in the fact that the location magnitude and slip vector of the most recent event are all very well documented we wished to determine whether or not the previous few ruptures of the fault were similar to the recent one we chose a site at a step over between two major strike slip traces where the principal fault is a normal fault our two excavations across the 1999 rupture reveal fluvial sands and gravels with two colluvial wedges related to previous earthquakes each wedge is about 0 8 m thick considering the processes of collapse and subsequent diffusion that are responsible for the formation of a colluvial wedge we suggest that the two paleoscarps were similar in height to the 1999 scarp this similarity supports the concept of characteristic slip at least for this location along the fault accelerator mass spectrometry ams radiocarbon dates of 16 charcoal samples are consistent with the interpretation that these two paleoscarps formed during large historical events in 1509 and 1719 if this is correct the most recent three ruptures at the site have occurred at 210 and 280 year intervals

surface rupture and slip distribution of the 12 november 1999 duzce earthquake m 7 1 north anatolian fault bolu turkey the 12 november 1999 earthquake m 7 1 occurred on the duzce fault a splay of the north anatolian fault in the bolu basin approximately three months after the 17 august 1999 m 7 4 earthquake the surface rupture was 40 km long and the maximum right lateral offset was 500 5 cm averaging 300 cm the 9 km of the westernmost part of the rupture along the southern margin of the eften lake had a 350 cm maximum vertical displacement normal faulting some of which was already ruptured during the 17 august 1999 event with few tens of centimeters the surface rupture has a generally simple narrow deformation zone of 0 5 5 m however in some places it widens to 50 m transtensional and transpressional structures were observed within releasing and restraining step over areas respectively the larger dextral offsets on some streams indicate previous events the dextral slip measurements along the rupture reflect a symmetric distribution the eastern connection of this rupture zone with the main trace of north anatolian fault remains unclear because the bakacak and elmalik fault which are connecting faults had no surface rupture manuscript received 14 november 2000

seismicity of the sea of marmara turkey since 1500 summary we use the earthquake history of the last 500 years to help evaluate the tectonic and hazard contexts of the1999 earthquakes at izmit and dzce in westernturkey the 20th century has been unusually active but over the 500 year period the seismic moment release can account for the known right lateral shear velocity across the marmara region observed by gps two areas of known late quaternary faulting stand out as unusually quiet over this period the northwest shore of the sea of marmara and the southern branch of the north anatolian fault system between bursa and mudurnu

long term elasticity in the continental lithosphere modelling the aden ridge propagation and the anatolian extrusion process summary the evolution of the gulf of aden and the anatolian fault systems are modelled using the principles of elastic fracture mechanics usually applied to smaller scale cracks or faults the lithosphere is treated as a plate and simple boundary conditions are applied that correspond to the known plate boundary geometry and slip vectors the models provide a simple explanation for many observed geological features for the gulf of aden the model predicts why the ridge propagated from east to west from the owen fracture zone towards the afar and the overall form of its path the smaller en echelon offsets can be explained by upward propagation from the initially created mantle dyke while the larger ones may be attributed to the propagating rupture interacting with pre existing structures for anatolia the modelling suggests that the east anatolian fault was created before the north anatolian fault could form once both faults were formed however activity could switch between them the time scales over which this should take place are not known but evidence for switching can be found in the historical seismicity for aden and anatolia pre existing structures or inhomogeneous stress fields left from earlier orogenic events have modified the processes of propagation and without an understanding of the existence of such features the propagation processes cannot be fully understood furthermore a propagating fault can extend into an active region where it would not have initiated the north anatolian fault encountered slow but active extension when it entered the aegean about 5 ma and the stress field associated with the extending fault has progressively modified aegean extension in the central aegean activity has been reduced while to the north west on features such as the gulfs of evvia and corinth activity has been increased the field observation that major structures propagate and the success of simple elastic models suggest that the continental crust behaves in an elastic brittle or elastic plastic fashion even though laboratory tests may be interpreted to suggest viscous behaviour there are major problems in scaling from the behaviour of small homogeneous samples to the large heterogeneous mantle and large scale observations should be treated more seriously than extrapolations of the behaviour of laboratory experiments over many orders of magnitude in space and time the retention of long term elasticity and localised failure suggests a similar gross rheology for the oceanic and continental lithospheres even though it is incorrect to attribute differences in behaviour to the former being rigid i e elastic and the latter viscous oceanic and continental lithosphere behave in different ways unlike oceanic crust continental crust is buoyant and cannot be simply created or destroyed the process of thickening or thinning works against gravity preventing large displacements on extensional or contractional features in the upper mantle the equivalents of ridge or subduction systems are suppressed before they can accommodate large displacements and activity must shift elsewhere on the other hand strike slip boundaries and extrusion processes are favoured

microplate boundaries as obstacles to pre earthquake strain transfer in western turkey inferences from continuous geochemical monitoring abstract warm and hot spring water chemistry changes as well as soil gas radon release patterns have been monitored in western turkey alongside regional seismicity providing a multi disciplinary approach from january 2009 to may 2011 33 earthquakes with ml between 4 0 and 6 0 occurred in this seismically very active region the ml 6 0 earthquake occurred on 19 may 2011 in simav town of kutahya province at a location midway between dense multidisciplinary monitoring networks of marmara region mr and the aegean extensional province aep we previously reported on noteworthy precursory anomalies prior to several earthquakes ml 4 in the mr and aep but no precursory anomaly was detected prior to the ml 6 0 event on 19 may 2011 in simav kutahya province midway between dense multidisciplinary monitoring mr and aep networks although these networks operate within the theoretical strain radii of this earthquake dobrovolsky et al 1979 no reliable anomaly were found geodetic studies based on gps data have identified crustal blocks in this region the epicentral area of the simav event is located within a block tectonically separated from aep and mr thus we speculate that pre earthquake strain accumulation within the simav block did not effectively transfer to adjacent blocks where the mr and aep networks are located thereby providing an explanation for the absence of detectable anomalies moreover prior to some earthquakes quadrant features of geochemical transients have been found suggesting that soil radon anomalies appear in compressional quadrant s of pre earthquake strain distribution

suppression of large earthquakes by stress shadows a comparison of coulomb and rate and state failure stress shadows generated by california s two most recent great earthquakes 1857 fort tejon and 1906 san francisco substantially modified 19th and 20th century earthquake history in the los angeles basin and in the san francisco bay area simple coulomb failure calculations which assume that earthquakes can be modeled as static dislocations in an elastic half space have done quite well at approximating how long the stress shadows or relaxing effects should last and at predicting where subsequent large earthquakes will not occur there has however been at least one apparent exception to the predictions of such simple models the 1911 m 6 0 earthquake near morgan hill california occurred at a relaxed site on the calaveras fault we examine how the more complex rate and state friction formalism based on laboratory experiments might have allowed the 1911 earthquake rate and state time to failure calculations are consistent with the occurrence of the 1911 event just 5 years after 1906 if the calaveras fault was already close to failure before the effects of 1906 we also examine the likelihood that the entire 78 years of relative quiet only four m 6 earthquakes in the bay area after 1906 is consistent with rate and state assumptions given that the previous 7 decades produced 18 m 6 earthquakes combinations of rate and state variables can be found that are consistent with this pattern of large bay area earthquakes assuming that the rate of earthquakes in the 7 decades before 1906 would have continued had 1906 not occurred these results demonstrate that rate and state offers a consistent explanation for the 78 year quiescence and the 1911 anomaly although they do not rule out several alternate explanations

holocene coastal change in the ancient harbor of yenikapi istanbul and its impact on cultural history an extensive rescue excavation has been conducted in the ancient harbor of istanbul yenikapi by the sea of marmara revealing a depositional sequence displaying clear evidence of transgression and coastal progradation during the holocene the basal layer of this sequence lies at 6 m below the present sea level and contains remains of a neolithic settlement known to have been present in the area indicating that the sea level at 8 9 cal ka bp was lower than 6 m below present sea level advanced to its maximum at 6 8 7 cal ka bp drowning lykos stream and forming an inlet at its mouth after 3 cal ka bp coastal progradation became evident subsequent construction of the byzantine harbor theodosius 4th century ad created a restricted small basin and accumulation of fine grained sediments the sedimentation rate was increased due to coastal progradation and anthropogenic factors during the deposition of coarse grained sediments at the upper parts of the sequence 7th 9th centuries ad the harbor was probably abandoned after the 11th century ad by filling up with lykos stream detritus and continued seaward migration of the coastline

linear elastic fracture mechanics explains the past and present evolution of the aegean abstract geologically the deformation in the anatolian aegean region has been dominated by two processes the propagation of the north anatolian fault associated with the extrusion of the anatolian plateau and the north south stretching of the aegean we model gps data in the context of this understanding localised deformation zones are represented by dislocation elements which extend from the base of the lithosphere to the locking depth at the base of the seismogenic layer unlike other gps interpretations our models incorporate geological and seismological constraints to provide a robust description of the present day deformation of the anatolian aegean region we then show that the present day deformation observed by gps today is consistent with the continuation of the geological processes that started in the tertiary our approach is also consistent with the lithosphere preserving long term elastic strength and with the concepts of linear elastic fracture mechanics applying at a large scale

timing of late holocene paleoearthquakes on the hurunui segment of the hope fault implications for plate boundary strain release through south island new zealand the hurunui segment of the dextral slip hope fault extends for 42 km between the hope and hurunui river catchments and westward to harper pass at the main divide of south island we conducted paleoseismic soil and landscape dating studies in the upper hurunui valley to determine the timing of past earthquake ruptures along this geometric fault segment on a late holocene alluvial surface at matagouri flat a young channel system is displaced dextrally by 4 5 0 6 m which is attributed to the most recent faulting event a trench and soil pits excavated nearby yield evidence for the timing of the last two surface faulting events these events dated from a combination of radiocarbon dates relative soil tree and historical constraints modified within an oxcal analysis occurred at ca a d 1655 1835 and 1425 1625 the occurrence of two rupture events during the last 600 yr is consistent with previous estimates stating a short recurrence interval for the hurunui segment the most recent faulting event in our trenches predates the historic 1888 north canterbury amuri earthquake which ruptured the hope river segment to the east a comparison of the record from the hurunui segment with paleoseismic records from other segments along the hope fault zone indicates evidence for two or three rupture events within the last 700 900 yr within the age resolution of the current dates the data suggest that along strike rupture occurred along the majority of the hope fault zone between 120 and 360 yr ago i e a d 1650 1888 and may all postdate the most recent rupture of the alpine fault in ca a d 1717 in addition the timings of penultimate faulting events along the hurunui hope river and conway segments and the hanmer fault all fall in the range 400 700 yr ago these preliminary observations indicate that rupture of segments of the hope fault and indeed the alpine fault could occur as clusters that are years to decades apart rupture of the major plate boundary faults in the northern south island may therefore occur in sequences that are enhanced or even retarded by stress triggering and fault interactions

continuum of earthquake rupture speeds enabled by oblique slip earthquake rupture speed can affect ground shaking and thus seismic hazard seismological observations show that large earthquakes span a continuum of rupture speeds from slower than rayleigh waves up to p wave speed and include speeds that are predicted to be unstable by 2d theory this discrepancy between observations and theory has not yet been reconciled by a quantitative model here we present numerical simulations that show that long ruptures with oblique slip both strike slip and dip slip components can propagate steadily at various speeds including those previously suggested to be unstable the obliqueness of slip and the ratio of fracture energy to static energy release rate primarily control the propagation speed of long ruptures we find that the effects of these controls on rupture speed can be predicted by extending the 3d theory of fracture mechanics to long ruptures with oblique slip we propose that this model provides a quantitative framework to interpret supershear earthquakes to constrain the energy ratio of faults based on observed rupture speed and rake angle and to relate the potential rupture speed and size of future earthquakes to the observed slip deficit along faults

a new multilayered visco elasto plastic experimental model to study strike slip fault seismic cycle nowadays technological advances in satellite imagery measurements as well as the development of dense geodetic and seismologic networks allow for a detailed analysis of surface deformation associated with active fault seismic cycle however the study of earthquake dynamics faces several limiting factors related to the difficulty to access the deep source of earthquake and to integrate the characteristic time scales of deformation processes that extend from seconds to thousands of years to overcome part of these limitations and better constrain the role and couplings between kinematic and mechanical parameters we have developed a new experimental approach allowing for the simulation of strike slip fault earthquakes and analyze in detail hundreds of successive seismic cycle model rheology is made of multilayered visco elasto plastic analog materials to account for the mechanical behavior of the upper and lower crust and to allow simulating brittle ductile coupling postseismic deformation phase and far field stress transfers the kinematic evolution of the model surface is monitored using an optical system based on subpixel spectral correlation of high resolution digital images first results show that the model succeed in reproducing the deformation mechanisms and surface kinematics associated to the main phases of the seismic cycle indicating that model scaling is satisfactory these results are comforted by using numerical algorithms to study the strain and stress distribution at the surface and at depth along the fault plane our analog modeling approach appears then as an efficient complementary approach to investigate earthquake dynamics

the accommodation of large strains in the upper lithosphere of the earth and other solids by self similar fault systems the geometrical origin of b value plate tectonics has provided a method of visualizing the geometry of the deformation of the earth s lithosphere on a large scale the description is so concise that for many purposes it provides an explanation of geological processes that overshadows the need to understand the driving processes the mechanics of the zones between the plates are less well understood particularly in continental regions where large areas are subject to deformation both continuous and discontinuous models have been tried but both have obvious drawbacks

a statistical approach to relationships between fluid emissions and faults the sea of marmara case the sea of marmara is traversed by the north anatolian fault system and also presents abundant emission sites of methane gas into the water column in order to assess the spatial relationship between gas emissions and active faults the distribution of distances between gas emission sites and the nearest fault is calculated and compared with the distribution of distances between a uniform random distribution of points poisson process representing the null hypothesis of an absence of relationship between gas emissions and faults and the nearest fault interestingly the distance distribution for the poisson process is nearly exponential indicating that the fault map does not have a characteristic scale other than that representing the intensity of the fault network the distance distribution for the observed gas emissions is significantly narrower than that arising from the poisson process with a kolmogorov distance of 0 25 0 02 the crossing point between the two distributions defines the characteristic half width of the swath of gas emission sites around the mapped active faults for the whole sea of marmara data set a characteristic half width of 900 1000 m is found which matches the half width of the seafloor deformation zone observed around the main active fault when the same analysis is applied to zones covering the western high and the central high it is found that the swath of gas emissions is wider on the central high 2 km half width and not clearly related to the seafloor deformation zone there this difference is put in perspective with recent work showing that creep is occurring on the western segment of the main marmara fault this also causing microseismicity while the central istanbul silivri segment may have remained locked since the 1766 magnitude 7 earthquake this suggests that aseismic slip and not only earthquake occurrence effectively maintains high permeability conduits in fault zones in sediments

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

the earthquake of 1509 in the sea of marmara turkey revisited this article is interdisciplinary in nature relevant to the fields of both earth sciences and historiography which come together in the investigation of long term earthquake hazard taking here as an example the earthquake of 10 september 1509 which was associated with an inferred 70 30 km long offshore fault break in the sea of marmara m w 7 2 0 3 and with widespread damage in istanbul and the adjacent region this article emphasizes the need for systematic and consistent analysis of historical earthquake data and sets an example for such a task the re examination of this earthquake in the context of the long term seismicity of the region over the last 2000 yr and in comparison with larger historic and modern events in the region shows no macroseismic and to some extent no tectonic evidence that the 1509 earthquake was a catastrophic event it is one of the damaging shocks in the 17 century long history of istanbul of a magnitude that was smaller than the large events that can occur further east in the anatolian fault zone this is consistent with the evidence from seismic reflection surveys in the sea of marmara which shows that faults are generally less continuous offshore than onshore as well as from the long term seismicity of the region which is an implication of the opening up of the sea of marmara earthquakes and its association with relatively short faults compared with ruptures of great lengths in the anatolian fault zone further east which is dominated by strike slip

the 17 august 1999 izmit earthquake on 17 august 1999 an earthquake of magnitude 7 4 shook northwestern turkey details on the earthquake9s characteristics and effects across northwestern turkey are provided and are put in the historical context of previous earthquakes in the region the earthquake was the seventh in a series of earthquakes migrating westwards along the north anatolian fault since 1939 information on historical earthquakes modeling and estimates of the slip rate along the fault indicate that the location and severity of the earthquake should not have come as a surprise

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

relationships between along fault heterogeneous normal stress and fault slip patterns during the seismic cycle insights from a strike slip fault laboratory model abstract we use a strike slip fault analog model to study experimentally the role played by along fault non uniform and asymmetric applied normal stress on both coseismic slip and long term fault behavior our model is based on a visco elasto plastic multi layered rheology that allows to produce several hundreds of scaled analog microquakes and associated seismic cycles uniform or heterogeneous applied normal stress along the fault plane is imposed and maintained constant during the whole experiment durations our results suggest that coseismic slip patterns are strongly controlled by spatial normal stress variations and subsequent accumulated shear stress along fault strike major microquakes occur preferentially in zones of major shear stress asperities coseismic slip distributions exhibit a pattern similar to the along fault applied normal stress distribution the occurrence of isolated low to moderate microquakes where residual stresses persist around secondary stress asperities indicates that stress conditions along the fault also control the whole variability of fault slip events moreover when fault slip stability conditions are modulated by normal stress distribution our experiments suggest that the along fault stress heterogeneity influences the seismic cycle regularity and consequently long term fault slip behavior uniform applied normal stress favors irregular seismic cycles and the occurrence of earthquakes clustering whereas non uniform normal stress with a single high amplitude stress asperity generates strong characteristic microquake events with stable return periods together our results strengthen the assumption that coseismic slip distribution and earthquake variability along an active fault may provide relevant information on long term tectonic stress and could thus improve seismic hazard assessment

coseismic and early post seismic slip associated with the 1999 izmit earthquake turkey from sar interferometry and tectonic field observations summary we use combined tectonic field observations and sar data to determine an improved model of the slip associated with the 1999 izmit earthquake which ruptured the north anatolian fault at the eastern end of the sea of marmara the leading goal is to understand the main features of the coseismic and post seismic deformation which are captured together in the sar data to achieve this we make a critical analysis of the ers1 2 sar data which allows atmospheric effects to be identified and removed we also use detailed field mapping and measurements of the earthquake surface rupture dislocations in elastic half space and a forward modelling strategy allow us to obtain a slip model by steps a trial and error approach is combined with conventional inversion techniques to determine the slip in the different regions of the fault the sar data are well explained with three main zones of high slip along the fault releasing a total moment of 2 3 10 20 nm mw 7 6 which is higher than the seismological estimates 1 7 2 0 10 20 n m the inhomogeneous slip distribution correlates with fault segments identified at the surface the izmit rupture appears to have extended 30 km west of the hersek peninsula into the sea of marmara with slip tapering fro m2mt ozero the western end of the rupture is located 40 km sse from istanbul we show that some features seen near to mudurnu and gevye and previously interpreted as slip on secondary faults are explained mostly as atmospheric effects correlated with the topography using our approach and the available gps data we obtain a slip model that represents the coseismic slip alone which suggests that the moment release during the main shock was 1 9 10 20 nm mw 7 5 consistent with the seismological estimates we conclude that the sar data include the effects of 2 m of fast after slip during the month following the main shock within a zone of the fault located 12 24 km below the epicentral region near the hypocentre at a depth of 18 km the fault appears to have experienced dynamic slip of 1 m associated with the main shock followed by 2 m of rapidly decelerating post seismic shear during the following month we suggest that the distribution of heterogeneous slip and loading along the different fault segments may be important factors controlling the propagation of large earthquake ruptures along the north anatolian fault

tectonic and sedimentary controls on widespread gas emissions in the sea of marmara results from systematic shipborne multibeam echo sounder water column imaging understanding of the evolution of fluid fault interactions during earthquake cycles is a challenge that acoustic gas emission studies can contribute a survey of the sea of marmara using a shipborne multibeam echo sounder with water column records provided an accurate spatial distribution of offshore seeps gas emissions are spatially controlled by a combination of factors including fault and fracture networks in connection to the main marmara fault system and inherited faults the nature and thickness of sediments e g occurrence of impermeable or gas bearing sediments and landslides and the connectivity between the seafloor and gas sources particularly in relation to the eocene thrace basin the relationship between seepage and fault activity is not linear as active faults do not necessarily conduct gas and scarps corresponding to deactivated fault strands may continue to channel fluids within sedimentary basins gas is not expelled at the seafloor unless faulting deformation or erosional processes affect the sediments on topographic highs gas flares occur along the main fault scarps but are also associated with sediment deformation the occurrence of gas emissions appears to be correlated with the distribution of microseismicity the relative absence of earthquake induced ground shaking along parts of the istanbul silivri and princes islands segments is likely the primary factor responsible for the comparative lack of gas emissions along these fault segments the spatiotemporal distribution of gas seeps may thus provide a complementary way to constrain earthquake geohazards by focusing the study on some key fault segments e g the northern part of the locked princes islands segment

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

features of earthquake occurrence in a complex normal fault network results from a synthetic seismicity model of the taupo rift new zealand 1 the taupo rift in the central north island of new zealand is a region of active extension of up to 15 mm yr in the back arc of the hikurangi subduction system mapping and trenching has defined a network of active normal faults because the paleoseismic and historical earthquake catalogs are short and inhomogeneous a deterministic computer model of seismicity has been constructed to better understand the earthquake history the model consists of 26 primary normal fault segments corresponding to mapped faults with vertical displacement rates of 0 1 1 6 mm yr and 4700 randomly distributed small normal faults in a 40 25 km area all of the model faults interact elastically parameters of the model are adjusted to reproduce the geologically observed displacement rates a regional b value of 1 0 and average slip event of 1 m the result is a long catalog of 500 000 events magnitude 3 82 to 6 62 which simulates a time period of 2 myr characteristic slip events on each segment are mostly well defined and their recurrence times can usually be described by a three parameter weibull distribution the coefficient of variation cv for recurrence intervals ranges from 0 12 to 1 22 with an average of 0 66 these reduce by about half if fault interactions are turned off the time series of characteristic earthquakes shows clear evidence of triggered slip up to about 3 years after large magnitude events followed by relative seismic quiescence on all segments the moment release rate is relatively stable over time periods of more than about five recurrence intervals 2 20 kyr but can vary on time scales less than that

stress accumulation and increased seismic risk in eastern turkey abstract unlike the north anatolian fault zone which has produced 11 large earthquakes since 1939 the east anatolian fault zone eafz has been relatively quiescent in the last century when compared to historical records and has therefore accumulated significant stresses along its length determination of the location and likely magnitude of a future probable earthquake along the eafz is of interest both because of this history of large earthquakes m 8 and the density of population in the area here we calculate stress evolution along the fault zone due to both seismic and tectonic loading since 1822 a sequence of 10 well constrained historical earthquakes is selected and the resulting stresses are calculated summed with tectonic loading stresses and resolved onto the mapped active faults we identify two areas of particular seismic risk one of which might be expected to yield a large event our results are sensitive to the previous history of large earthquakes in the region and indicate a need for detailed investigations to constrain the exact rupture geometries of previous earthquakes on these segments

active faults in the sea of marmara western turkey imaged by seismic reflection profiles turkey is moving westward relative to eurasia thereby accommodating the collision between arabia and eurasia this motion is mostly taken up by strike slip deformation along the north and east anatolian faults the sea of marmara lies over the direct westward continuation of the north anatolian fault zone just east of the sea of marmara the north anatolian fault splits into three strands two of which continue into the sea while the locations of the faults are well constrained on land it has not yet been determined how the deformation is transferred across the sea of marmara onto the faults on the west coast of turkey we present results from a seismic reflection survey undertaken to map the faults as they continue through the three deep marmara sea basins of clnarclk central marmara and tekirdag in order to determine how the deformation is distributed across the sea of marmara and how it is taken up on the western side of the sea the data show active dipping faults with associated tilting of sedimentary layers connecting the north anatolian fault to strike slip faults that cut the biga and gallipoli peninsulas