source estimation and direct wave reconstruction in laplace domain waveform inversion for deep sea seismic data summary we propose a strategy to overcome the high sensitivity to early time noise of the laplace domain waveform inversion in deep sea seismic data this problem is particularly crucial to obtaining accurate velocity structures to this end rather than simply filtering or muting early time data we propose replacing the original noise contaminated direct waves with analytically computed noise free waves to reconstruct the noise free direct waves we compute green s functions for half space media estimate the source wavelet from the original direct waves using the full newton method in the frequency domain and then convolve the green s functions with the estimated source wavelet the data obtained by merging the reconstructed direct waves with the original late time data set can then be used for laplace and laplace fourier domain waveform inversions to verify the source estimation and direct wave reconstruction strategy we applied it to field data acquired in a deep sea environment and obtained a realistic 2 d velocity model the source estimation and direct wave reconstruction methods can also be applied to 3 d laplace domain waveform inversion

river drainage patterns in the new zealand alps primarily controlled by plate tectonic strain the persistence of dendritic drainage patterns implies that rivers reorganize after a tectonic perturbation preserving no long term record of that tectonic event numerical simulations of the evolution of drainage patterns in the southern alps new zealand however reveal rivers that resist reorganization and thus preserve a record of plate tectonic strain over 10 million years

a missing link in the tectonic configuration of the almacik block along the north anatolian fault zone nw turkey active faulting in the bolu plain based on seismic reflection studies

modes and rates of horizontal deformation from rotated river basins application to the dead sea fault system in lebanon partitioning of horizontal deformation between localized and distributed modes in regions of oblique tectonic convergence is in many cases hard to quantify here we use the geometry of river basins and numerical modeling to evaluate modes and rates of horizontal deformation associated with the arabia sinai relative plate motion in lebanon we focus on river basins that drain mount lebanon to the west and are bounded by the yammouneh fault a segment of the dead sea fault system that transfers left lateral deformation across the lebanese restraining bend we quantify a systematic counterclockwise rotation of these basins and evaluate drainage area disequilibrium using the metric the analysis indicates a systematic spatial pattern whereby tributaries of the rotated basins appear to experience drainage area loss or gain with respect to channel length a kinematic model reveals that since the late miocene 23 31 of the relative plate motion parallel to the plate boundary has been distributed along a wide band of deformation to the west of the yammouneh fault taken together with previous shorter term estimates the model indicates little variation of slip rate along the yammouneh fault since the late miocene kinematic model results are compatible with late miocene paleomagnetic rotations in western mount lebanon a numerical landscape evolution experiment demonstrates the emergence of a similar pattern of drainage area disequilibrium in response to progressive distributed shear deformation of river basins with relatively minor drainage network reorganization

quantifying differential rock uplift rates via stream profile analysis despite intensive research into the coupling between tectonics and surface processes our ability to obtain quantitative information on the rates of tectonic processes from topography remains limited due primarily to a dearth of data with which to test and calibrate process rate laws here we develop a simple theory for the impact of spatially variable rock uplift rate on the concavity of bedrock river profiles application of the analysis to the siwalik hills of central nepal demonstrates that systematic differences in the concavity of channels in this region match the predictions of a stream power incision model and depend on the position and direction of the channel relative to gradients in the vertical component of deformation rate across an active fault bend fold furthermore calibration of model parameters from channel profiles argued to be in steady state with the current climatic and tectonic regime indicates that 1 the ratio of exponents on channel drainage area and slope m n is 0 46 consistent with theoretical predictions 2 the slope exponent is consistent with incision either linearly proportional to shear stress or unit stream power n 0 66 or n 1 respectively and 3 the coefficient of erosion is within the range of previously published estimates mean k 4 3 10 4 m 0 2 yr application of these model parameters to other channels in the siwalik hills yields estimates of spatially variable erosion rates that mimic expected variations in rock uplift rate across a fault bend fold thus the sensitivity of channel gradient to rock uplift rate in this landscape allows us to derive quantitative estimates of spatial variations in erosion rate directly from topographic data

the geometry of the north anatolian transform fault in the sea of marmara and its temporal evolution implications for the development of intracontinental transform faults the north anatolian fault is a 1200 km long strike slip fault system connecting the east anatolian convergent area with the hellenic subduction zone and as such represents an intracontinental transform fault it began forming some 13 11 ma ago within a keirogen called the north anatolian shear zone which becomes wider from east to west its width is maximum at the latitude of the sea of marmara where it is 100 km the marmara basin is unique in containing part of an active strike slip fault system in a submarine environment in which there has been active sedimentation in a paratethyan context where stratigraphic resolution is higher than elsewhere in the mediterranean it is also surrounded by a long civilised rim where historical records reach well into the second half of the first millennium bce before common era in this study we have used 210 multichannel seismic reflexion profiles adding up to 6210 km profile length and high resolution bathymetry and chirp profiles reported in the literature

fluvial landscape response time how plausible is steady state denudation whether or not steady state topography and denudation are probable states depends on the timescale of system response to tectonic and climatic perturba tions relative to the frequency of those perturbations this paper presents analytical derivations of algebraic relations for the response time of detachment limited fluvial bedrock channel systems both to tectonic and climatic perturbations detachment limited fluvial erosion is described by the stream power incision model and the derivations are limited to the applicability of that model all factors likely to influence system response time that are not adequately captured by the stream power incision model will tend to increase the response time the calculations presented thus provide minimum estimates of landscape response time and therefore over predict the prob ability of attaining and sustaining steady state topography and denudation the central range of taiwan is used as a case study to estimate response times in a landscape often argued to be in steady state model parameters are fit to modern stream profiles by assuming that the topography represents a quasi steady state form estimated response times generally range from 0 25 to 2 5 ma depending on the non linearity of the incision rule and the magnitude and type of perturbation thus it may be reasonably argued that steady state topography and denudation are likely to prevail during periods of climatic stability response time is sufficiently short compared with plate tectonic timescales however rapid climatic fluctuation in the quaternary appears to preclude the attainment of steady state conditions in modern orogens motivation

kinematics of the mw 7 2 12 november 1999 duzce turkey earthquake the november 12 1999 duzce earthquake ruptured a 40 km long fault segment of the north anatolian fault system immediately to the east of the august 17 1999 izmit rupture we use displacements of 32 sites derived from gps measurements immediately before and after the duzce earthquake to estimate the geometry and slip distribution of the coseismic rupture the 51 northward dipping rupture plane the rake of the slip vector average 3 76 0 04 m right lateral 0 76 0 04 m normal slip and the slip distribution inferred from the gps data are consistent with seismic observations and the distribution of surface offsets measured in the field the geodetically determined moment magnitude is mw 7 2 the duzce earthquake had the highest slip to rupture length ratio of any historic earthquake along the north anatolian fault this is consistent with the duzce earthquake being a part of a composite rupture with the preceding izmit event

saturated and subcooled hydrothermal boiling in groundwater flow channels as a source of harmonic tremor the potential of hydrothermal boiling in groundwater flow channels for generating harmonic tremor a relatively monochromatic ground vibration associated with volcanic activity is examined we use simple organ pipe theory of normal mode fluid vibration and fundamental energy considerations to develop a first order analytical model of a hydrothermal boiling source of harmonic tremor we use this model to estimate order of magnitude groundwater flow channel lengths and boiling heat transfer rates required to produce harmonic tremor with dominant frequencies in the range 0 5 5 hz and surface wave reduced displacements of up to 100 cm2 depending on groundwater sound speed flow channel lengths of the order of 1 1000 m are required to produce fluid vibration eigenfrequencies in the range 0 5 5 hz the boiling heat transfer rate required to produce tremor with a given surface wave reduced displacement depends on the tremor frequency and on whether saturated boiling or subcooled boiling is the cause of the tremor saturated boiling produces groundwater vibration via steam bubble growth whereas subcooled boiling produces groundwater vibration via steam bubble collapse we find that subcooled hydrothermal boiling is from 102 to 104 times more efficient than saturated boiling in converting boiling thermal power to seismic power for example the boiling heat transfer rates required to produce 1 hz tremor with reduced displacements of up to 100 cm2 via subcooled boiling are generally less than a few thousand megawatts for saturated boiling the required boiling heat transfer rates are several orders of magnitude larger than this the highest values of heat flow reported in the literature for volcanic crater lakes and terrestrial and ocean floor geothermal areas are of the order of 1000 mw taking this value as a first order estimate of an upper limit on possible boiling heat transfer rates in volcanic hydrothermal systems our results suggest that saturated hydrothermal boiling is capable of generating only low amplitude harmonic tremor with surface wave reduced displacements no higher than a few square centimeters however subcooled hydrothermal boiling could potentially generate high amplitude harmonic tremor with reduced displacements as large as several hundred square centimeters as a specific application of our model we evaluate the potential of hydrothermal boiling for generating harmonic tremor at recently active mount st helens and nevado del ruiz volcanoes we conclude that subcooled boiling likely could have produced the tremor episodes considered at both volcanoes saturated boiling also could explain the nevado del ruiz tremor but probably not the more powerful mount st helens tremor

tectonic evolution of the marmara sea and its surroundings abstract the basins in the marmara sea are the products of a superimposed evolutionary history defined by two different aged fault systems the early miocene early pliocene thrace eskisehir fault zone and its branches and the late pliocene recent north anatolian fault and its branches the thrace eskisehir fault and its westward branching secondary fault systems define the early neotectonic signature in the region the late neotectonic period started at the end of the early pliocene when the north anatolian fault divided the thrace eskisehir fault into four parts during the late neotectonic period the north anatolian fault extended westward as a number of splays by joining with the ganos bandirma behramkale and manyas edremit fault zones the branches of the north anatolian fault zone nafz caused the evolution of a number of basins which differ in character depending on the trend and past characteristics of the older branches that became connected since the northern branch of the north anatolian fault is connected to the n80 e trending ganos fault zone gfz in the west a single buried fault has developed in the marmara sea causing the well known troughs and ridges superimposed onto the negative flower structure formed by the gfz in the early neotectonic period the middle strand which extends from iznik lake to bandirma is oriented east west up to the n60 e trending bandirma behramkale fault zone then turns southward in the vicinity of bandirma forming a region dominated by compressional tectonics this bending caused n30 e trending tension in addition to the strike slip motion between the eastern part of gemlik bay and bandirma bay the southern branch of the nafz on the other hand produced three pull apart basins with different characteristics along the yenisehir bursa and manyas segments the southern branch of the nafz connected to the manyas edremit fault zone which is oriented n45 e to the south of manyas and the associated bending and rotation caused a n15 e trending extension in addition to the strike slip regime between manyas and uluabat the branches of north anatolian fault cut through the thrace eskisehir fault at three places the east marmara sea region in gemlik bay and to the east of bursa giving lateral offsets of 58 59 7 8 and 10 11 km respectively the cumulative motion is 75 78 km corresponding to the total lateral offset of the north anatolian fault in the region the correlation of these offsets with global positioning system slip vectors and with stratigraphic results implies that the north anatolian fault reached into the marmara sea region about 3 5 million yr ago tectonic processes forming the marmara sea and its environs were initiated by the thrace eskisehir fault and its splays have been most recently controlled by the north anatolian fault and its splays during the last 3 5 million yr

block rotation by strike slip faulting structural and paleomagnetic evidence geometric analysis shows that motion of sets of strike slip faults should cause block rotation otherwise the distorted fault domain would not fit with its surrounding the sense of the block rotation depends on the sense of fault slip and the spacing and orientation of the faults all of which can be obtained from structural data the predictions of the geometric model can then be independently tested by paleomagnetic measurements the model was tested in northern israel structural data reveal several domains of contemporaneous right and left lateral strike slip faults paleomagnetic measurements show that in a domain of nnw trending left lateral faults blocks rotated 23 3 8 2 clockwise and in a domain of right lateral faults blocks rotated 22 4 9 0 anticlockwise these results are in agreement with the prediction of the geometric analysis of the structure the combined results of the heterogenous deformation of the area resembles a pure shear which allows n s extension by about 1 3 in other domains rotations of 34 6 9 1 and 53 1 11 0 were found in their original orientation the left and right lateral faults intersected at angles of 60 70 enclosing the principal axis of shortening in accordance with theories of brittle failure as a result of block rotations this angle is now larger and may reach 110 the results demonstrate large block rotations in different senses in domains of strike slip faults the independent structural and paleomagnetic data can be interpreted within the framework of a simple geometric model northern israel is considered to be a good model for this efficient mechanism of intraplate deformation which is expected to occur in similar tectonic settings elsewhere

a complex seismogenic shear zone the duzce segment of north anatolian fault turkey abstract this work highlights how surface geological data can integrate and complete a fault characterization including its seismogenic depth we investigated the area struck by the november 1999 mw 7 1 earthquake that ruptured the duzce segment of the north anatolian fault zone nafz after the august 1999 mw 7 4 izmit earthquake to explore the persistency or evolution of the active fault setting at the surface we compared detailed coseismic surface expressions with the long term morphology and structural architecture of the duzce zone we identified a simple 1999 coseismic fault trace cft and an older complex fault system rfs involving a wider zone of deformation two different parts of the duzce segment were recognized a western section presents a staircase trajectory of the coseismic fault trace that reactivated part of the older fault system an eastern section presents a straight coseismic fault trace that cross cuts the older and complex fault system the western duzce fault segment splays out from the izmit counterpart of the nafz forming a releasing fault junction by comparing a model of its coseismic surface deformation field with the long term morphology we observed that the present topography of this western section results from the nafz activity by repeating coseismic deformations like those in 1999 the mechanical interaction in the release fault junction produces local transtension across the western duzce fault and justifies its stable complexity it does not evolve into a straight trace the surface boundary between the duzce fault sections also separates at depth two fault sections one with low slip to the west and another with a big asperity to the east thus the izmit duzce interaction 1 may produce an unfavorable setting for a build up of asperities in the western duzce segment and 2 could delay the propagation of the izmit rupture along the duzce segment that nucleates mainshocks only on its eastern section in other words the arrangement of the fault junction may permanently control how the two sections of the duzce fault behave and rupture

regional clockwise rotation of the armutlu peninsula western turkey resolved from palaeomagnetic study of eocene volcanics abstract the north anatolian fault naf one of the major tectonic entities of turkey is a dextral fault system lying within an intracontinental transform zone up to 100 km in width this shear zone is composed of continental blocks delimited by strike slip faults with the armutlu peninsula being one of the largest of these blocks and surrounded by two main branches of the naf such fault bounded blocks typically display rotations and a variety of different kinematic models have been proposed to explain these in this study eocene volcanic rocks of the armutlu peninsula have been sampled from 50 palaeomagnetic sites following alternating field and thermal demagnetisation and component analysis a dual polarity axis is resolved which shows that the peninsula has rotated 16 6 8 clockwise relative to the predicted field direction at this location in eocene times this clockwise block rotation is interpreted in terms of dextral motion of a tectonic block bounded by two strands of the naf the palaeomagnetic data also indicate that the eocene rocks of the armutlu peninsula were emplaced at a palaeolatitude statistically identical to the present and we conclude that northward movement of this sector of the anatolides since eocene times has been below the limits of palaeomagnetic detection

geomorphic expression of active tectonics in a rapidly deforming forearc sila massif calabria southern italy we examine the tectonic geomorphology of la sila calabria southern italy a high standing 1500 m plateau surrounded by crustal extension with map dem and field data these data are used to constrain a simple geodynamic model that describes short wavelength deformation of the plateau rim topographic metrics including drainage patterns river longitudinal profiles and swath profiles are consistent with field stratigraphic relationships collectively suggesting that local tectonic deformation is embedded within a broader regional uplift that has increased the mean elevation of the sila plateau during the quaternary the concavity steepness and length gradient index of modeled river longitudinal profiles proved to be the most useful metrics for recording the effects of locally active faults a previously unrecognized horst on the northeastern portion of the plateau was identified with these data nevertheless the core of the sila plateau remains relatively undeformed with respect to its flanks which are characterized by steep fault bounded escarpments active extension has dropped base level for and unloaded the plateau rim causing deep fluvial incision and associated flexural uplift of the footwall this footwall uplift helps maintain a separate external and nearly radial drainage away from the plateau along its flanks and a nearly closed drainage for the plateau interior a drainage divide roughly correlates with the plateau rim inhibiting the process of drainage integration through the sila interior and subsequent landscape dissection as a result geomorphic processes driving erosion of the sila upland are lagging behind the tectonic processes that have driven rock uplift leading to an overall increase in mean surface elevation these results underscore the importance of the lag times a landscape may endure in transforming from one tectonic and base level condition to another we conclude that the calabrian forearc has a similar geomorphic evolution as the more northern apennines consistent with the emerging view that growth of apennine topography has been recent quaternary rapid and possibly decoupled from rock deformation in the orogenic wedge

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

single domain chemical thermochemical and thermal remanences in a basaltic rock summary tiny basaltic samples containing finely grained titanomagnetite with curie temperature less than 100 c were heated in air in weak field 25 100 t at temperatures between 400 c and 560 c for times as long as 32 hr oxyexsolution of titanomagnetite resulted in the crystallization of interacting single domain particles with curie point close to 540 c and the concomitant development of one of two types chemical remanence depending upon thermal treatment isothermal chemical remanence crm or thermochemical remanence tcrm the latter acquired under the combined effects of chemical change and temperature decrease crm and tcrm acquired under various conditions were subjected to thellier type experiments all these treatments were carried out using a vibrating sample thermomagnetometer allowing the continuous recording of magnetization and a very precise temperature control all crm trm and tcrm trm plots were found to be linear over almost the entire trm blocking temperature range whether ptrm checks are positive or not an apparent strength of the acquisition field of crm or tcrm could thus be obtained and divided by the actually applied field to obtain a ratio r which is representative of the crm trm or tcrm trm ratios over most of the unblocking blocking temperature spectrum for crm it is found that r is less than 1 and increases rapidly with acquisition temperature 0 36 0 07 at 400 c 0 66 0 02 at 450 c and 0 90 0 02 at 500 c in qualitative agreement with expressions derived from the theory of non interacting single domain grains thus very large underestimate of geomagnetic field palaeostrength can occur when a natural crm is not recognized as such and is believed to be a natural trm palaeointensity data obtained from geological material prone to the development of secondary minerals as for example baked contacts and volcanic glasses have therefore to be considered with caution in an attempt to mimic deuteric oxyexsolution in cooling magma tcrm was imparted from 560 c to 400 c at a cooling rate of 0 1 c min in contrast to the crm case r is found to slightly exceed 1 1 11 0 05 according to theoretical considerations this finding suggests that in practice tcrm approximates to trm

rates and timing of vertical axis block rotations across the central sierra nevada walker lane transition in the bodie hills california nevada 1 we use paleomagnetic data from tertiary volcanic rocks to address the rates and timing of vertical axis block rotations across the central sierra nevada walker lane transition in the bodie hills california nevada samples from the upper miocene 9 ma eureka valley tuff suggest clockwise vertical axis block rotations between ne striking left lateral faults in the bridgeport and mono basins results in the bodie hills suggest clockwise rotations r r 95 confidence limits of 74 8 since early to middle miocene 12 20 ma 42 11 since late miocene 8 9 ma and 14 10 since pliocene 3 ma time with no detectable northward translation the data are compatible with a relatively steady rotation rate of 5 2 ma 1 2 since the middle miocene over the three examined timescales the average rotation rates have probably not varied by more than a factor of two over time spans equal to half of the total time interval our paleomagnetic data suggest that block rotations in the region of the mina deflection began prior to late miocene time 9 ma and perhaps since the middle miocene if rotation rates were relatively constant block rotation in the bodie hills is similar in age and long term average rate to rotations in the transverse ranges of southern california associated with early transtensional dextral shear deformation we speculate that the age of rotations in the bodie hills indicates dextral shear and strain accommodation within the central walker lane belt resulting from coupling of the pacific and north america plates

channel changes in badlands stripping of the vegetation and soil from a 13 hectare site in virginia underlain by coastal plain sediments created a rapidly evolving badland topography two types of channels developed 1 sand bed alluvial channels were graded to transport the bed material load supplied from slope erosion with available runoff but they also generally eroded their beds slowly and 2 steeper bedrock floored channels incised rapidly in bedrock channels the erosion rate was proportional to the 4 9ths power of drainage area and the 2 3rds power of gradient these exponents are consistent with a model in which the erosion rate is proportional to the bed shear during high flows due to rapid mass wasting and reduced runoff the alluvial channels became as much as 50 steeper during the winter than the summer with an attendant yearly cycle of winter aggradation and summer entrenchment the gradients their seasonal variability and their downstream hydraulic geometry were consistent with the predictions of total load transport formulas for sand beds and high loads the hydraulic geometry of alluvial channels in the virginia badlands were similar to that on the morrison formation in the western united states

deformational behaviour of continental lithosphere deduced from block rotations across the north anatolian fault zone in turkey abstract theoretical considerations of lithosphere deformation across transform plate boundaries predict an expression in terms of 3istributed deformation the magnitude of rotation is expected to diminish away from the fault zone in a way which depends on the length of the fault the amount of displacement and the ductility of the lithosphere palaeomagnetic studies across the north anatolian transform fault zone which separates the eurasian plate and anatolian block in northern turkey show that clockwise rotations predicted from the sense of dextral motion are indeed present and have attained finite rotations of up to 270 during the 5 ma history of neotectonic deformation such rotations are however confined to narrow 10 km wide zones between system bounding faults and appear to have resulted from rotation in ball bearing fashion of equidimensional blocks a few kilometres in size outside of this zone only anticlockwise rotations are observed these are unrelated to deformation across the fault zone and record regional anticlockwise rotation of turkey which is complementing clockwise rotation of greece and accompanying neogene opening of the aegean sea the observed behaviour of continental lithosphere satisfies no plausible value of power law behaviour we therefore conclude that relative motion across this transform boundary occurs as a discrete zone of intense deformation within a brittle layer comprising the seismogenic upper crust this is presumed to be detached from a continuum deformation response to shearing in the lower crust and mantle beneath

late cenozoic uplift along the northern dead sea transform in lebanon and syria an edited version of this paper was published in earth and planetary science letters by elsevier science elsevier science retains the copyright to this paper copyright 2006 elsevier science see also http dx doi org 10 1016 j epsl 2005 10 029 http atlas geo cornell edu deadsea publications gomez2006 epsl htm

step over and bend structures along the 1999 duzce earthquake surface rupture north anatolian fault turkey the 12 november 1999 duzce earthquake m w 7 1 which occurred on the duzce fault of the north anatolian fault zone formed a 40 km long surface rupture which extended between golyaka in the west and kaynasli in the east the earthquake nucleated close to the beykoy step over a 0 8 km wide and 1 8 km long pressure ridge with bilateral rupture propagation both to the west and the east the beykoy kaynasli and cevizlik step overs through which the 1999 duzce rupture propagated are less than 2 5 km wide the eften and bakacak step overs where the rupture was arrested are more than 4 km wide these exceptional dimensions of step overs associated with the 1999 duzce rupture were investigated for their influ ence on rupture propagation the earthquake broke three distinct geometric segments from west to east the eften dagdibi and kaynasli fault segments separated by left restraining step overs at beykoy and kaynasli to the west of the main shock 3 5 m of average slip on the eften fault segment propagated into the 2 km wide cevizlik releasing double bend where it was largely arrested with smaller 0 5 m slip continuing westward on the golyaka intervening segment west of lake eften this is similar to the ter mination of slip observed on the karadere fault segment in the 1999 izmit earthquake where 1 5 m of slip was largely terminated by a releasing double bend at the golyaka intervening segment with minor slip continuing eastward near lake eften to the east of the main shock 5 m of slip decreased along the dagdibi fault segment to about 3 5 m at the 1 km wide kaynasli step over from here to the east the 2 5 m of average slip on the kaynasli fault segment continued to decrease reaching zero at the releasing step overs to the elmalik fault the terminations of the 1999 duzce surface rupture are defined by distinct struc tural complexities the rupture was arrested in the west at the 4 km wide eften releasing double bend where the eastern termination of the 1999 izmit rupture also occurred to the east the rupture terminated at the 4 to 5 km wide bakacak releasing double step overs both eastern and western ends of the duzce rupture have short fault segments that experienced minor rupture during the 1999 duzce earthquake the golyaka intervening segment experienced minor rupture during both the 1999 izmit and duzce earthquakes the duzce rupture propagated across 0 8 to 2 km wide step overs but it was arrested at step overs 4 km wide or wider these results agree with the observations on ratios between step over width in kilometers and strike slip displacement in meters collected along strike slip faults worldwide let tis et al 2002

landscape response to tectonic forcing digital elevation model analysis of stream profiles in the mendocino triple junction region northern california the topographic evolution of orogens is fundamentally dictated by rates and patterns of bedrock channel incision quantitative field assessments of process based laws are needed to accurately describe landscape uplift and denudation in response to tectonics and climate we evaluate and calibrate the shear stress or similar unit stream power bedrock incision model by studying stream profiles in a tectonically active mountain range previous work on emergent marine terraces in the mendocino triple junction region of northern california provides spatial and temporal control on rock uplift rates digital elevation models and field data are used to quantify differences in landscape morphology associated with along strike northwest to southeast changes in tectonic and climatic conditions analysis of longitudinal profiles supports the hypothesis that the study area channels are in equilibrium with current uplift and climatic conditions consistent with theoretical calculations of system response time based on the shear stress model within uncertainty the profile concavity of the trunk streams is constant throughout the study area 0 43 as predicted by the model channel steepness correlates with uplift rate these data help constrain the two key unknown model parameters the coefficient of erosion k and the exponent associated with channel gradient n this analysis shows that k cannot be treated as a constant throughout the study area despite generally homogeneous substrate properties for a reasonable range of slope exponent values n best fit values of k are positively correlated with uplift rate this correlation has important implications for landscape evolution models and likely reflects dynamic adjustment of k to tectonic changes due to variations in orographic precipitation and perhaps channel width sediment load and frequency of debris flows the apparent variation in k makes a unique value of n impossible to constrain with present data

palaeogeographical evolution of the thrace neogene basin and the tethys paratethys relations at northwestern turkey thrace abstract the thrace neogene basin situated in northwestern turkey was initiated by strike slip faulting that was active from the early miocene until the end of the pliocene during the early miocene it began to form under the control of the thrace eskisehir fault zone initiated by continental collision in northwestern anatolia late oligocene early miocene during the late early miocene the basin was a site of mainly fluviatile and limnic sedimentation to the west and marine sedimentation via the paratethyan transgression in the north with the onset of the middle miocene the thrace block started to rotate in a counterclockwise sense and escaped westward with respect to the strandja istanbul block owing to rejuvenation of fossil fault systems within it in this period warm marine conditions were also established around the gulf of saros through a mediterranean originated transgression during the middle late miocene fluviatile and limnic conditions were created over the western thrace by the westerly propagation of the thrace eskisehir fault zone one of the principal results of the early middle miocene tectonics is the tilting of the strandja istanbul block to the south severing the tethys and the paratethys during the latest miocene early pliocene period the thrace eskisehir fault zone was deactivated because of the evolution of the north anatolian fault zone to the south the resurrected ganos fault zone situated on the dissected fossil suture zone in the sea of marmara also joined the north anatolian fault zone uplifting the gelibolu peninsula and thus severing the connection that existed between the sea of marmara and the paratethys the sea of marmara eventually became an endemic basin by the activity of the north anatolian fault zone

has focused denudation sustained active thrusting at the himalayan topographic front the geomorphic character of major river drainages in the himalayan foothills of central nepal suggests the existence of a discrete west northwest trending break in rock uplift rates that does not correspond to previously mapped faults the 40 ar 39 ar thermochronologic data from detrital muscovites with provenance from both sides of the discontinuity indicate that this geomorphic break also corresponds to a major discontinuity in cooling ages samples to the south are proterozoic to paleozoic whereas those to the north are miocene and younger combined these observations virtually require recent pliocene holocene motion on a thrust sense shear zone in the central nepal himalaya 20 30 km south of the main central thrust field observations are consistent with motion on a broad shear zone subparallel to the fabric of the lesser himalayan lithotectonic sequence the results suggest that motion on thrusts in the toe of the himalayan wedge may be synchronous with deeper exhumation on more hinterland structures in central nepal we speculate that this continued exhumation in the hinterland may be related to intense sustained erosion driven by focused orographic precipitation at the foot of the high himalaya

deformation during the 12 november 1999 duzce turkey earthquake from gps and insar data only 87 days after the mw 7 5 17 august 1999 izmit earthquake the duzce earthquake ruptured a ca 40 km long adjoining strand of the north anatolian fault naf system to the east we used displacements of 50 global positioning system gps sites together with interferometric synthetic aperture radar insar range change data spanning the event to estimate the geometry and slip distribution of the coseismic rupture postseismic deformation transients from the duzce earth quake and the preceding i zmit event that are included in some of the measurements are corrected for using dislocation models fit to gps data spanning the various time periods nonlinear inversions for fault geometry indicate that the rupture occurred on a ca 54 north dipping oblique normal right lateral fault distributed slip inver sions indicate maximum strike slip near the center of the duzce fault close to the earthquake hypocenter slip magnitude and depth of faulting decrease to the west and east of the hypocenter both gps and insar data suggest that normal slip is restricted to the shallow portion of the rupture the duzce earthquake had the highest slip to rupture length ratio of any historic earthquake along the naf

seismotectonic setting of the karadere duzce branch of the north anatolian fault zone between the 1999 izmit and duzce ruptures from analysis of izmit aftershock focal mechanisms abstract we investigate aftershock focal mechanisms along the eastern part of the izmit mw 7 4 august 17 1999 rupture zone during the time period august 22 1999 october 17 1999 two spatial clusters of aftershock activity are analyzed representing the karadere fault kf and the duzce area da based on an aftershock hypocenter catalogue restricted to events with horizontal and vertical errors 10 km events north and east of the easternmost end of the karadere fault we observe a high variance in stress field orientation correlated with lower b values while the karadere fault reflects a predominant dextral strike slip regime with normal faulting components the duzce area further to the east that also hosted the forthcoming mw 7 2 mainshock 87 days after the izmit earthquake can be subdivided into a dominantly ne sw extensional normal faulting regime below the duzce basin db and a first order strike slip regime along the western duzce fault df we conclude that the duzce basin was set under tension by the izmit rupture and partly released the slip deficit by extensional faulting on karadere fault parallel to the coseismic displacement at the same time this area and in particular the duzce fault that bounds the duzce basin to the south reflects mostly strike slip events representing a major asperity along the north anatolian fault zone nafz before initiating the duzce rupture 87 days after the izmit event

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

active intracontinental transpressional mountain building in the mongolian altai defining a new class of orogen abstract mountain ranges that are actively forming around the western and northern perimeter of the indo eurasia collisional deformational field such as the mongolian altai comprise a unique class of intracontinental intraplate transpressional orogen with structural and basinal elements that are distinct from contractional and extensional orogens late cenozoic uplift and mountain building in the mongolian altai is dominated by regional scale dextral strike slip faults that link with thrust and oblique slip faults within a 300 km wide deforming belt sandwiched between the more rigid junggar basin block and hangay precambrian craton dominant orogenic elements in the mongolian altai include double restraining bends terminal restraining bends partial restraining bends single thrust ridges thrust ridges linked by strike slip faults and triangular block uplifts in areas of conjugate strike slip faults the overall pattern is similar to a regional strike slip duplex array however the significant amount of contractional and oblique slip displacement within the range and large number of historical oblique slip seismic events renders the term transpressional duplex more accurate intramontane and range flanking basins can be classified as ramp basins half ramp basins open sided thrust basins pull apart basins and strike slip basins neither a classic fold and thrust orogenic wedge geometry nor a bounding foredeep exists the manner in which upper crustal transpressional deformation is balanced in the lower crust is unknown however crustal thickening by lower crustal inflation and northward outflow of lower crustal material are consistent with existing geological and geodetic data and could account for late cenozoic regional epeirogenic uplift in the russian altai and sayan regions

proterozoic ophiolites and mafic ultramafic complexes marginal to the istanbul block an exotic terrane of avalonian affinity in nw turkey abstract among the proterozoic inliers in the istanbul block the lowest structural levels are exposed in the sunnice massif north of bolu amphibolite facies mafic and subordinate ultramafic rocks of the cele meta ophiolite underlie the greenschist facies ediacaran calc alkaline yellice metavolcanics which are intruded by the 565 576 ma dirgine granitoids hornblende gneisses of the cele meta ophiolite comprise island arc meta tholeiites and transitional to calc alkaline metabasalts which together with minor serpentinite are disposed in a broadly antiformal structure the meta ophiolitic rocks are therefore the oldest ophiolites in nw turkey and are themselves thrust on to a putative pre existing continental margin now represented by the metasedimentary migmatites of the demirci gneisses which may thus be the oldest rocks of the complex the istanbul block is an exotic terrane unlike other western turkish terranes it lacks variscan metamorphism its different provenance indicated by its geological record faunal affinities and inherited mid proterozoic isotopic dates suggests a former link with avalonian basement in england nw europe and the maritime provinces of canada hence together with other terranes now situated further east than the avalonian terranes of nw europe the istanbul block may represent the easternmost extremities of avalonia which were detached during its end ordovician collision with the bruno silesian promontory on the sw margin of baltica subsequent migration of the istanbul block to its present location occurred by eastward displacement by sinistral transpression along the southern margin of baltica to a point east of the dobrogea and south of the scythian platform followed by collision with the sakarya block in the mesozoic and late cretaceous southward displacement with the opening of the black sea basin

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

morphotectonic development of the marmara region abstract the marmara region of northwest turkey covers the marmara sea basin and the surrounding lands in the region morphologically different areas may be distinguished the marmara sea basin is a structural depression the land to the north is known as the thrace kocaeli peneplain a flatland elevated above a horst this may be referred to as the istanbul horst bounded by two strike slip fault zones which define the structural boundaries of two sea basins the black sea in the north and the marmara sea in the south the southern boundary fault is part of the north anatolian transform fault zone nafz which cuts through the region in the e w direction and extends to the aegean sea region the land to the south of the marmara sea is a plateau about 300 to 800 m high known as the bursa balikesir plateau it has a rather rugged topography represented by nw and ne trending ridges separated by depressions the ridges and the depressions correspond to horsts and grabens respectively the data reveal that the marmara region has passed through the following morphotectonic evolution together with the surrounding region it suffered a long period of denudation between the oligocene and the end of the late miocene which formed a regionwide peneplain the n s extensional regime followed this phase and began to produce a horst graben system and thus fragmented the peneplain the flat lying erosional surfaces have been elevated above the horsts later the nafz reached the marmara region in the initial stage it affected nw anatolia extensively as a wide right lateral shear regime this has evolved and through time the present narrow fault zone has developed the major morphological difference between the regions to the north and the south of the marmara sea basin is mainly related to the nafz as a plate boundary it formed a barrier to the n s extension saving the northern sector from the effect of the extension the southern region has gradually elevated to much higher altitudes

estimation of the long term slip surface uplift and block rotation along the northern strand of the north anatolian fault zone inferences from geomorphology of the almacik block abstract the almacik block is one of the key morphotectonic units in the eastern marmara region associated with the long term slip partitioning within the north anatolian fault zone nafz in this study we provide new geomorphic reconstructions of offset drainage basins morphometric analysis of topography and longitudinal profiles of the rivers crossing different flanks of the almacik block our geomorphic reconstructions of offset drainage basins along the hendek and karadere faults imply mean offsets of 2 3 0 4 km and 8 4 0 7 km respectively during the quaternary our dataset also imply that slip partitioning occurs in a broader zone than previously proposed and that the total 10 7 0 6 km offset along the hendek and karadere faults of the northern strand must be taken into account for long term slip partitioning in the eastern marmara region together with previously suggested 10 km offset along the southern strand yaltirak 2002 16 1 0 km offset along the middle strand ozalp et al 2013 and the 52 1 0 km offset along the mudurnu segment of the northern strand akbayram et al 2016 our newly proposed geomorphic markers raise the cumulative offset in the eastern marmara region associated with the naf to 89 1 0 km since the latest pliocene quaternary in addition to these lateral displacements our morphometric analysis and longitudinal profiles of the rivers imply up to 1130 130 m surface uplift of the almacik block as a combined result of vertical displacement within the deformation zone of the northern strand of the nafz finally by assuming that river basins act as passive deformation markers our basin azimuth analyses imply 20 2 clockwise rotation of the almacik block associated with the nafz

the relationship between strain rates crustal thickening palaeomagnetism finite strain and fault movements within a deforming zone the deformation of continental lithosphere generally does not occur on a single fault but is distributed over a zone up to a few hundred kilometers wide if the deformation rate is constant throughout the zone and if the velocity is continuous everywhere and does not change with time the deformation gradient tensor can be obtained analytically this tensor directly determines the amount of crustal thickening and is related in a complicated manner to the finite strain tensor the declination of remnant magnetization measured within the zone can also be rotated by the deformation because palaeomagnetic measurements are generally made on rigid blocks which have not been deformed there is no simple relationship between such rotations and the finite strain expressions for all these quantities are obtained in terms of the velocity gradients which are taken to be constant the history of western north america is used to illustrate the relationship between the present deformation by strike slip and thrust motions the rotations of the remnant magnetization vectors and the shape of accreted terranes at the surface distributed deformation is taken up by motion on faults which separate the zone into blocks the displacement rate on the faults their strike and the finite rotations of the blocks are all controlled by the velocity gradients analytic expressions relating these quantities are obtained a deforming zone containing normal faults which crosses central greece takes up both strike slip and extension and illustrates the relationship between the structures within and the motion across the zone a similar but more complicated zone in northeastern iran involves both strike slip and shortening

new constraints on micro seismicity and stress state in the western part of the north anatolian fault zone observations from a dense seismic array with the aim of extensively investigating the crustal structure beneath the western segment of the north anatolian fault zone where it splays into northern and southern branches a temporary seismic network dense array for north anatolia dana consisting of 70 stations was deployed in early may 2012 and operated for 18 months in the sakarya region during the faultlab experiment out of 2437 events contaminated by explosions we extracted 1371 well located earthquakes the enhanced station coverage having a nominal station spacing of 7 km lead to a minimum magnitude calculation of 0 1 horizontal and vertical location uncertainties within the array do not exceed 0 8 km and 0 9 km respectively we observe considerable seismic activity along both branches of the fault where the depth of the seismogenic zone was mostly confined to 15 km using our current earthquake catalog we obtained a b value of 1 we also mapped the b value variation with depth and observed a gradual decrease furthermore we determined the source parameters of 41 earthquakes with magnitudes greater than 1 8 using p wave first motion polarity method regional moment tensor inversion method was also applied to earthquakes with magnitudes greater than 3 0 focal mechanism solutions confirm that sakarya and its vicinity is stressed by a compressional regime showing a primarily oblique slip motion character stress tensor analysis indicates that the maximum principal stress is aligned in wnw ese direction and the tensional axis is aligned in nne ssw direction

cenozoic tectonic evolution of the new zealand plate boundary zone a paleomagnetic perspective abstract new zealand straddles the obliquely convergent boundary between the pacific and australian plates with subduction of pacific plate along the hikurangi margin finite plate reconstructions predict 800 km of relative plate motion since 43 ma with 80 90 clockwise rotation of the hikurangi margin since 20 ma at an average rate of 4 4 5 myr and the short term deformation

palaeomagnetic evidence for substantial rotation of the almacik flake within the north anatolian fault zone nw turkey summary palaeomagnetic data on eocene rocks from within the almacik flake bounded by two strands of the north anatolian right lateral fault indicate that the flake has undergone an apparent counterclockwise rotation of about 148 on average we interpret this as a real 212 clockwise rotation because the almacik flake is entirely delimited by the right lateral north anatolian fault strands the only dominant post eocene structure in the area and because areas surrounding the flake do not show the same rotation this rotation must have occurred since the north anatolian fault originated in the late medial miocene late serravallian 11 5 ma and if so may imply either a larger total slip along it than hitherto estimated or that the almacik flake is the surface expression of a flower structure rotating above a shear zone narrower than the present width of the flake

multi phased uplift of the southern margin of the central anatolian plateau turkey a record of tectonic and upper mantle processes abstract uplifted neogene marine sediments and quaternary fluvial terraces in the mut basin southern turkey reveal a detailed history of surface uplift along the southern margin of the central anatolian plateau from the late miocene to the present new surface exposure ages 10be 26al and 21ne of gravels capping fluvial strath terraces located between 28 and 135 m above the goksu river in the mut basin yield ages ranging from ca 25 to 130 ka corresponding to an average incision rate of 0 52 to 0 67 mm yr published biostratigraphic data combined with new interpretations of the fossil assemblages from uplifted marine sediments reveal average uplift rates of 0 25 to 0 37 mm yr since late miocene time starting between 8 and 5 45 ma and 0 72 to 0 74 mm yr after 1 66 to 1 62 ma together with the terrace abandonment ages the data imply 0 6 to 0 7 mm yr uplift rates from 1 6 ma to the present the different post late miocene and post 1 6 ma uplift rates can imply increasing uplift rates through time or multi phased uplift with slow uplift or subsidence in between longitudinal profiles of rivers in the upper catchment of the mut and ermenek basins show no apparent lithologic or fault control on some knickpoints that occur at 1 2 to 1 5 km elevation implying a transient response to a change in uplift rates projections of graded upper relict channel segments to the modern outlet together with constraints from uplifted marine sediments show that a slower incision uplift rate of 0 1 to 0 2 mm yr preceded the 0 7 mm yr uplift rate the river morphology and profile projections therefore reflect multi phased uplift of the plateau margin rather than steadily increasing uplift rates multi phased uplift can be explained by lithospheric slab break off and possibly also the arrival of the eratosthenes seamount at the collision zone south of cyprus

characterization of aftershock fault plane orientations of the 1999 izmit turkey earthquake using high resolution aftershock locations 1 joint inversion for hypocentral parameters and the velocity field is nowadays a state of the art tool to obtain high resolution images of seismically active regions in this study we focus on the location accuracy of aftershocks of the 1999 mw 7 4 izmit nw turkey earthquake we obtained a new velocity model for the region and depicted its improvement on absolute locations in terms of uncertainty and misfit two well developed aftershock clusters located in the akyazi area and karadere duzce region were analyzed in detail based on a waveform cross correlation approach that allowed improving the location accuracy by a factor of 6 relocation results reveal that hypocenters form narrow planes of activity that can be correlated with focal mechanisms of the larger aftershocks as well as nearby clouds of activity with no internal structure down to the resolved scale of 300 m

slip rate variability and distributed deformation in the marmara sea fault system the slip rate along a fault controls the accumulation of strain that is eventually released during an earthquake estimates from a three dimensional geomechanical model of the slip rate on the main marmara fault near istanbul turkey reconcile geodetic and geological observations and indicate smaller values and higher variability than previously thought the slip rate along a fault controls the accumulation of strain that is eventually released during an earthquake1 along a 150 km long stretch of the north anatolian fault near istanbul turkey strain has been building up2 since the last large earthquake in 1766 estimates of the geodetic slip rates along the main marmara fault vary widely ranging between 17 and 27 9 mm yr 1 refs 2 3 4 5 this slip rate is difficult to quantify because of the lack of satellite observations offshore and the complexity of the submarine fault system that includes the main marmara fault2 6 7 here we estimate the right lateral slip rate on the main marmara fault using a three dimensional geomechanical model that incorporates these structural complexities from our simulations we infer slip rates between 12 8 and 17 8 mm yr 1 our estimates are smaller and more variable than previous results primarily because of slip partitioning and internal deformation our model results reconcile geodetic observations and geological fault slip rates8 9 10 which had been considered conflicting previously we suggest that the inferred variability in slip rate on the main marmara fault favours segmented release of seismic moment during consecutive events over the failure of the whole seismic gap in one large earthquake

the geometry of the active strike slip el tigre fault precordillera of san juan central western argentina integrating resistivity surveys with structural and geomorphological data the geometry and related geomorphological features of the right lateral strike slip el tigre fault one of the main morphostructural discontinuities in the central western precordillera of argentina were investigated achievements of this survey include recognition of structural and geometrical discontinuities along the fault trace identification and classification of landforms associated with local transpressional and transtensional sectors observation of significant changes in the fault strike and detection of right and left bends of different wavelength in the central segment of the el tigre fault 2d electrical resistivity tomography surveys were carried out across the fault zone the resistivity imaging permitted to infer the orientation of the main fault surface the presence of blind fault branches along the fault zone tectonic tilting of the quaternary sedimentary cover subsurface structure of pressure ridges and depth to the water table based on this information it is possible to characterize the el tigre fault also as an important hydro geological barrier our survey shows that the main fault surface changes along different segments from a high angle to a subvertical setting whilst the vertical slip component is either reverse or normal depending on the local transpressive or transtensive regime induced by major bends along the trace these local variations are expressed as sections of a few kilometres in length with relatively homogeneous behaviour and frequently separated by oblique or transversal structures

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

paleomagnetic evidence of complex tectonic rotation pattern in the nw anatolian region implications for the tectonic history since the middle eocene abstract the kinematic evolution of the almacik block and the armutlu region which are surrounded by the branches of the north anatolian fault is not completely understood because of incompatible paleomagnetic data a previous paleomagnetic study in the almacik block indicated that there have been large rotations associated with the rotation as a whole coherent block and another study postulated a more complex tectonic evolution the aim of this study was to obtain paleomagnetic directions on middle eocene volcanic volcanoclastic rocks at 25 sites in nw anatolia and to determine the tectonic deformation process along the north anatolian fault zone after rock magnetic measurements and stepwise thermal and alternating field demagnetisation most of the samples taken were characterised by one component of magnetisation after the removal of viscous magnetisation a characteristic remanent magnetisation was obtained at 500 580 c showing evidence of magnetite and titanomagnetite with a small amount of ti however in some cases a high temperature component was isolated between 600 and 650 c indicating a titanohematite composition the mean direction obtained from the istanbul zone d 191 5 i 47 1 95 7 1 indicated no tectonic rotation relative to the reference direction of the stable eurasian plate d 191 0 i 53 2 95 5 0 besse and courtillot 2002 torsvik et al 2008 in the middle eocene the paleomagnetic directions in the almacik block and the armutlu region suggest counterclockwise rotations of 22 3 7 8 and 17 7 14 6 respectively relative to the istanbul zone when integrated together with previous studies our paleomagnetic results indicate that both the armutlu region and the almacik block were emplaced in the same area during the middle eocene the deformation of the northern branch of the north anatolian fault resulted in a bend and an overstep fault offset of 25 km between lake sapanca and lake abant during this process both the almacik block and the armutlu region were separated distinctly from each other with a counter clockwise rotation with respect to the istanbul zone in addition within some parts of the almacik block an internal deformation with large declination anomalies ranging from 160 to 250 was observed in this study and in previous studies these different declinations could be the result of chemical remagnetisation of hydrothermal events stress related magnetisation or small block rotations

slip history of the 1944 bolu gerede earthquake rupture along the north anatolian fault system implications for recurrence behavior of multisegment earthquakes 1 recent research shows that active fault systems produce multisegment earthquakes however we have yet to understand the faulting behavior of various spatial patterns of segments we conducted a three dimensional trenching survey to reconstruct the detailed slip history of a fault segment that ruptured as one of the multisegment ruptures along the north anatolian fault system the trench site on the gerede segment recorded a maximum right lateral slip of up to 6 m that was associated with the 1944 bolu gerede earthquake m 7 4 fault exposures show evidence of four paleoearthquakes radiocarbon dates a refined probability density distribution and correlation with historical earthquakes place the mean repeat time at 330 years four discrete paleoslips yield a slip per event of 5 0 0 8 m with a coefficient of variation of 0 2 our research suggests that multisegment earthquakes exhibit various spatial patterns regardless of recurrence with quasiperiodicity and characteristic slip coincidentally the fault geometry exhibits extremely linear traces suggesting simple stress accumulation and release through earthquake cycles furthermore the 1944 event did not occur in a single segment and the gerede segment probably ruptured within a slip pulse like rupture during a multisegment earthquake a comparable geological slip rate of 17 mm a 1 based on a gps based strain rate supports the persistence of macroscopic asperity through recent geological time therefore we conclude that a segment with simple fault geometry along a strike slip fault system plays an important role in forecasting the timing of future multisegment earthquakes but the spatial extent of such earthquakes needs to be explored further

experiments on strike slip faulting and block rotation analogue model experiments investigating strike slip faulting in zones of distributed shear deformation show that fault orientations and fault evolution indicate modifications of the stress field with increasing bulk shear strain dextral bulk shear deformation at low strain is accommodated dominantly by synthetic strike slip faults riedel shears at higher strain secondary antithetic and synthetic faults develop mostly between earlier formed major riedel shears closely spaced parallel antithetic faults cross faults delimit domains that rotate about vertical axes with continuing shear deformation rotation of fault bounded domains results in sigmoidal antithetic faults that have a dip slip component and a dip direction that changes along strike there is good agreement between models and natural examples of distributed shear zones where block rotations about vertical axes have been documented

the morphology of strike slip faults examples from the san andreas fault california fault zones are seldom straight nor are fractures within them continuous permanent strain fields are imprinted near a fault of complex geometry as a result of continued slip these strain fields may be manifest as vertical deformation near the fault strain fields that increase area result in subsidence and strain fields that reduce area result in uplift although these effects are modified by erosion and deposition the general features of fault zone morphology are a consequence of the geometry and slip distribution along strike graphical views of strain fields associated with simple vertical strike slip faults are derived using boundary element methods if the fault is straight and parallel to the applied shear strain the hills and valleys resulting from finite fault rupture are separated by the fault trace this is rarely observed in nature instead strike slip faults cut through hills and valleys apparently of their own making we show this to be a consequence of segments of the fault being nonparallel to each other and to the overall applied shear strain coseismic strains are large but transient since they are substantially annulled by rupture on contiguous fault segments we test our theory with examples from parts of the san andreas fault system in california the morphologies of the parkfield region and the southern san andreas fault in the coachella valley are shown to be consistent with plausible distributions of slip on mapped surface faults the location of the salton sea appears to be a consequence of a reduction of slip on the san andreas fault toward the brawley seismic zone

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

distribution of active rock uplift along the eastern margin of the tibetan plateau inferences from bedrock channel longitudinal profiles 1 current models of long term river incision into bedrock suggest that the local rate of differential rock uplift should exert a primary control on the gradient of channel longitudinal profiles however discrimination of this effect from the influence of variations in substrate erodibility sediment flux precipitation and transient changes in profile shape has proved difficult in practice here we investigate the controls on the spatial distribution of bedrock channel gradients adjacent to the sichuan basin in an effort to assess the degree and nature of active deformation along this margin of the tibetan plateau analysis of river longitudinal profiles utilizing a channel steepness index a measure of profile gradient normalized for drainage area reveals a zone of anomalously steep channels adjacent to the topographic front of the plateau margin channel profiles are systematically less steep in their headwater reaches on the plateau and in their lower reaches east of the plateau margin comparison of steepness indices to mapped lithologic variations reveals that lithology has only a limited influence on channel gradient in this field area we observe no systematic relationship between steepness indices and upstream drainage area channels of all size are steeper near the plateau margin we argue that these systematic changes are not readily explained as a consequence of increased sediment flux or of orographic precipitation we are led to conclude that steep channel profiles along the topographic front of the plateau reflect active differential rock uplift between this region and the foreland

use of a regional relict landscape to measure vertical deformation of the eastern tibetan plateau 1 field work and topography analysis show that remnant local areas of a low relief landscape or erosion surfaces are geographically continuous across the southeastern tibetan plateau margin we correlate these remnant surfaces as a paleolandscape that formed at low elevation remnants of this paleolandscape are preserved because incision of the fluvial system has been largely limited to major rivers and principal tributaries and has not yet progressed throughout the entire fluvial network the incomplete adjustment of the fluvial system signals initiation of rapid bedrock incision into a developing plateau margin and erosional denudation is concentrated in the major river channels this interpretation contradicts earlier notions that low gradient regional topography is the product of regional elevation reduction by intense landscape dissection due to the presence of several large southeast flowing rivers the modern altitude of the reconstructed paleolandscape or relict landscape constrains the vertical displacement of the plateau surface in response to crustal thickening and subsequent erosion during the lateral growth of the tibetan plateau regional preservation of the relict landscape is consistent with minor surface disruption by late cenozoic thrust faults and folds and supports a model of distributed lower crustal thickening because significant erosion is limited to narrow river gorges an increase in the plateau elevation due to isostatic rebound is minor therefore we propose that the modern elevation of the relict landscape reflects isostatically compensated thickening of the lower crust

geomorphic response of coastal streams to low intermediate and high rates of uplift medocino triple junction region northern california analysis of three dimensional morphological properties of 24 coastal drainage basins that have evolved in areas of low 3 m 1 000 yr rates of uplift near the mendocino triple junction mtj coastal northern california identified channel gradients as the best indicator of tectonism in the landscape lower order tributaries best reflect tectonically controlled differences the largest streams examined of third order are able to adjust to most base level change and maintain their profile form whereas lower order streams farther upstream tend to accumulate the effects of net base level fall and have steepest profiles in the areas of highest uplift rates variations in steepness of first order channel gradients indicate that 1 high uplift rates in the wake of the mtj have existed for at least 73 000 yr and 2 differential tilt of the region to the north and south of the current locus of highest uplift rate is occurring in association with regional uplift although first order streams are excellent indicators of areas of both high uplift rates and regional differential tilting they are less useful in distinguishing between areas of low and intermediate uplift rate analysis of the longitudinal profile of the main trunk stream of ten of the 24 drainage basins using the stream gradient index was more useful to categorize broadly the uplift rates and to distinguish between streams in low and intermediate uplift rate areas although the hypotheses tested herein do not identify the exact mechanism off uplift in the mtj region they do indicate that the nature of deformation is most likely regional tilt rather than crustal shortening with localized compressional folding and thrust faulting they also indicate that geomorphic responses trail in the wake of the uplift rate response caused by development of a slab window beneath the north american plate 1 maximum uplift rates occur 9 km south of the northern boundary of the slab window 2 maximum mean first order channel gradient occurs 16 km south of the northern edge of the slab window and 3 maximum drainage basin relief occurs 20 km south of the northern edge of the slab window associated lag times between passage of the southern edge of the subducted gorda plate slab and geomorphic responses are 160 000 yr for maximum uplift rates 290 000 yr for maximum channel gradients and 370 000 yr for maximum relief