long range earthquake forecasting with every earthquake a precursor according to scale scaling relations previously derived from examples of the precursory scale increase before major earthquakes show that the precursor is a long term predictor of the time magnitude and location of the major earthquake these relations are here taken as the basis of a stochastic forecasting model in which every earthquake is regarded as a precursor the problem of identifying those earthquakes that are actually precursory is thus set aside at the cost of limiting the strength of the resulting forecast the contribution of an individual earthquake to the future distribution of hazard in time magnitude and location is on a scale determined through the scaling relations by its magnitude provision is made for a contribution to be affected by other earthquakes close in time and location e g an aftershock may be given low weight using the new zealand catalogue the model has been fitted to the forecasting of shallow earthquakes exceeding magnitude 5 75 over the period 1965 2000 it fits the data much better than a baseline poisson model with a location distribution based on proximity to the epicenters of past earthquakes further the model has been applied with unchanged parameters to the california region over the period 1975 2001 there also it performs much better than the baseline model fitted to the same region over the period 1951 1974 the likelihood ratio is 1015 in favor of the present model these results lend credence to the precursory scale increase phenomenon and show that the scaling relations are pervasive in earthquake catalogues the forecasting model provides a new baseline model against which future refinements and other proposed models can be tested it may also prove to be useful in practice its applicability to other regions has still to be established

organic geochemistry and origin of late glacial holocene sapropelic layers and associated sediments in marmara sea abstract organic geochemistry of two sapropel sapropelic sediment units dated 10 6 6 4 and 3 8 3 2 kyr bp and associated sediments in two gravity cores from the marmara sea were studied to characterize the organic matter and discuss its paleoceanographic implications vertical trends of c n ratio 13c and hydrogen indices show that the flooding of the marmara sea by the mediterranean waters at 12 kyr bp and onset of deposition of the lower sapropelic layer at 10 6 yr bp are characterized with a high input of terrestrial organic matter this terrestrial input decreased and marine organic matter contribution increased in time towards the top of the upper sapropelic layer at 3 2 kyr bp the lower sapropelic layer is broadly the same age and has a similar distribution of organic matter type as the s1 sapropel of the aegean sea suggesting their depositions may have been controlled by the same events both the lower marmara sapropelic layer and the aegean s1 sapropel were probably deposited during a time of high influx of organic rich river waters from the black sea this influx of black sea water could have induced water stratification in the marmara sea and aegean sea and lead to the deposition of the sapropels

sedimentary features of the seismo turbidites lake biwa japan abstract seismo turbidite layers are deposited at the foot of the steep slope of the half graben in which lake biwa has accumulated sedimentary studies especially of grain size distribution of selected turbidites provide excellent information for clarifying the distinctive features of general seismo turbidites development of the two constituent sublayers lower sandy sublayer and upper silt sublayer lack or limited appearances of traction indicating structures and characteristic grain size distribution in the two constituent sublayers are most remarkable and significant the characteristic grain size distribution features are coarse tail grading in a relatively thick sandy sublayer exceptionally rapid distribution grading through the thin boundary interval between the two sublayers height increase and fluctuation of the silt mode and high clay content brief discussion was made on the causes of these sedimentary features the need and importance of further comparative studies of various turbidites known triggering forces are emphasized

late pleistocene holocene evolution of the northern shelf of the sea of marmara abstract chirp sub bottom profiling multibeam bathymetric mapping and a combination of faunal and isotopic analysis of molluscs and foraminifera in sediment cores on the northern shelf of the sea of marmara som provide evidence of sea level excursions water exchanges between the adjacent mediterranean and black seas and oscillating salinity over the last 160 ka bp during the marine isotope stages mis 2 mis 3 mis 4 and mis 6 the som disconnected from the mediterranean sea and evolved into a lake during mis 1 mis 5 and mis 7 the som reconnected and became salty once again sapropels formed shortly after each invasion of mediterranean saltwater observed in our cores concurrent suboxic dysoxic conditions prevailed over quite shallow substrates on the shelf ancient shorelines are pervasive at 85 m on the northern shelf and in the region of prince islands coincident with the elevation of the modern bedrock sill in the canakkale dardanelles strait at times when global eustatic sea level dropped below this sill the surface of the som stabilized at its outlet and freshened thus this particular shoreline is interpreted as the edge of the most recent som lake that existed from about 75 ka bp to 12 ka bp the freshening is observed in very light 6 values of 18 o measured on freshwater molluscs and the complete absence of foraminifera two brief lacustrine episodes during mis 5 suggest that the level of the canakkale outlet might have been as shallow as 50 m in the past a likelihood supported by submerged terraces along its margins bounding the modern central channel and the presence of an euryhaline biofacies in unit l4 1 corresponding to mis 5b 18 o profiles and carbon 14 dating show that salinification of the som and the blossoming of bioherms evolved rapidly after the latest connection with the mediterranean at 12 ka bp however freshening proceeded more slowly once the connection was severed

mixture models for improved earthquake forecasting with short to medium time horizons abstract optimal mixtures of three space time magnitude earthquake likelihood models are found for forecasting earthquakes with magnitudes of 5 0 and greater in the new zealand and california catalogs with forecasting time horizons ranging from 0 to 3000 days the models are the epidemic type aftershock etas short term clustering model the every earthquake a precursor according to scale eepas medium term clustering model and the proximity to past earthquakes ppe quasi time invariant smoothed seismicity model the etas model is by far the most informative of these models for short time horizons of a few days but even with a zero time horizon an optimal mixture of the three models here called the janus model outperforms it with an information gain per earthquake igpe of about 0 1 for time horizons of 10 3000 days the janus model outperforms the most informative of its component models with igpes ranging from 0 2 to 0 5 as the time horizon lengthens beyond six months in new zealand and two years in california the eepas model becomes the most informative of the individual models and the major component of the optimal mixture changes in the janus model parameters with the forecasting time horizon reveal features of time and area scaling of precursory seismicity the results suggest that both cascades of triggering and the precursory scale increase phenomenon contribute to earthquake predictability and that these contributions are largely independent

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

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

tsunamis in the sea of marmara historical documents for the past models for the future abstract more than 30 tsunami events have impacted the coasts of the sea of marmara in the past two millennium clustering in izmit bay the shores of istanbul gemlik bay the shores of the kapidag and gelibolu peninsulas with respect to the last well known tsunami the izmit tsunami of 17 august 1999 available field survey run up data and marine surveys provide an opportunity to evaluate how these events were triggered the main purpose of this study is to determine the slope failure potential as a possible tsunamigenic source in the sea of marmara by utilising multi beam bathymetry shallow and deep seismic reflection data on the basis of the landslide geomorphology the generation propagation and coastal amplifications of tsunamis related to earthquake and slope failure scenarios were tested by using tsunami simulation model two layer the maximum water surface elevations near the shores along the north and south coasts are obtained according to the selected scenarios of tsunami generation by using available data

human impact on land ocean sediment transfer by the world s rivers abstract land ocean transfer of sediment by rivers is a key pathway for material transfer on earth contemporary data on the sediment loads of rivers provide clear evidence of significant recent changes in the sediment fluxes of several rivers in response to human impact the key drivers of increased sediment loads include land clearance for agriculture and other facets of land surface disturbance including logging activity and mining although programmes for soil conservation and sediment control can result in reduced sediment loads the trapping of sediment by dams represents the dominant cause of reduced loads this influence is currently assuming increasing importance at the global scale any attempt to link these drivers to changes in the global land ocean sediment flux must take account of the aggregation and buffering effects that operate in larger basins which can cause damping and even removal of signals of increasing flux within the upstream basin and complicate the link between upstream and downstream response to human impact further work is required to provide a precise quantitative assessment of the human impact on global land ocean sediment fluxes and the net effect of increasing and decreasing fluxes particular attention must be paid to the temporal perspective and the variation of impact trajectories in different areas of the globe and for river basins of different sizes

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

deciphering hemipelagites from homogenites through anisotropy of magnetic susceptibility paleoseismic implications sea of marmara and gulf of corinth abstract in closed marine basins and large lakes gravity re depositional processes often result in specific turbidites with two abruptly separated layers a coarse graded lower term and an upper homogenous fine grained term an additional mixed term generally occurs in between indicating to and from particle displacements the later ones are related to oscillating bottom currents responsible for a high increase of the fine fraction segregation within the reworked wasted mass the whole sedimentary event is the association homogenite turbidite hmtu which specific a settling condition area here characterized through anisotropy of magnetic susceptibility ams homogenites s magnetic foliation appears anomalously high with respect to their expected state of compaction and strikingly higher than hemipelagites s values we applied this approach to late pleistocene holocene sediments from the sea of marmara and from the gulf of corinth grain size and other magnetic parameters related to mineralogy are added to better assess the granular array influence on ams as hmtu is considered as often related to earthquake triggering and tsunami seiche effects ams appears as a useful tool for subaqueous paleoseismic investigations first it may evidence the signature of paleo earthquakes second it permits to decipher hemipelagic intervals which are inferred to represent the time elapsed between two successive reworking events

demarcation and scaling of long term seismogenesis a space time envelope of minor seismicity related to major shallow earthquakes is identified from observations of the long term precursory scale increase phenomenon which quantifies the three stage faulting model of seismogenesis the envelope which includes the source area of the major earthquake is here demarcated for 47 earthquakes from four regions with tectonic regimes ranging from subduction to continental collision and continental transform the earthquakes range in magnitude from 5 8 to 8 2 and include the 24 most recent mainshocks of magnitude 6 4 and larger in the san andreas system of california the hellenic arc region of greece and the new zealand region together with the six most recent mainshocks of magnitude 7 4 and larger in the pacific arc region of japan also included are the destructive earthquakes that occurred at kobe japan 1995 magnitude 7 2 izmit turkey 1999 magnitude 7 4 and w tottori japan 2000 magnitude 7 3 the space a p in the space time envelope is optimised with respect to the scale increase while the time t p is the interval between the onset of the scale increase and the occurrence of the earthquake a strong correlation is found between the envelope a p t p and the magnitude of the earthquake hence the conclusion that the set of precursory earthquakes contained in the envelope is intrinsic to the seismogenic process yet a p and t p are correlated only weakly with each other suggesting that a p is affected by differences in statical conditions such as geological structure and lithology and t p by differences in dynamical conditions such as plate velocity among other scaling relations predictive regressions are found between on the one hand the magnitude level of the precursory seismicity and on the other hand both t p and the major earthquake magnitude hence the method as here applied to retrospective analysis is potentially adaptable to long range forecasting of the place time and magnitude of major earthquakes

long range earthquake forecasting allowing for aftershocks summary an earthquake occurrence model aimed at forecasting main shocks can be adjusted to allow for the occurrence of aftershocks conforming to well known empirical relations describing their temporal decay magnitude distribution and spatial extent modifications are proposed to the every earthquake a precursor according to scale eepas long range forecasting model to allow for the occurrence of aftershocks of predicted events using earthquake catalogues of california and the kanto region central japan versions of the modified and original eepas model are fitted to a period of about 10 yr and independently tested on a later period of about 10 yr of each catalogue for the testing period the increase in the log likelihood per earthquake of the modified models over their original counterparts is about 0 1 on average this gives preliminary confirmation of the efficacy of the modifications versions of the modified model will be submitted to regional testing centres of the collaboratory for the study of earthquake predictability for further independent performance testing in real time

late glacial to holocene climate and sedimentation history in the nw black sea abstract gravity cores from the continental slope in the northwestern black sea were studied using high resolution stable isotope grain size and xrf scanning data the measurements provide a 30 000 years ams 14c dated record of variations in the hydrological regime of the black sea and give insight into changing paleoenvironments in the surrounding areas stable climatic conditions during the last glacial maximum were followed by a series of meltwater pulses most likely originating from the scandinavian ice sheet between 18 000 and 15 500 yr bp 1 this meltwater input rose the level of the caspian sea to a point that caspian water could spill into the black sea via the manych depression north of the caucasian mountains high frequency oscillations in the xrf data during this period suggest a probable link to the arctic climate regime later during the bolling allerod and the early holocene prevailing high temperatures led to authigenic calcite precipitation through increased phytoplankton activity interrupted by the younger dryas and the 8200 yr bp cold event with dominant clastic sedimentation

a new proxy for bottom water ventilation in the eastern mediterranean based on diagenetically controlled magnetic properties of sapropel bearing sediments magnetic properties of eastern mediterranean sediments recovered during leg 160 of the ocean drilling program odp provide insight into non steady state diagenetic reactions associated with accumulation and degradation of organic matter in sapropels according to their magnetic properties sapropels can be classified as one of three types that correspond to increasingly anoxic conditions at the time of sapropel formation a combination of magnetic and geochemical data suggests a causal relationship that enables determination of the relative role of bottom water ventilation versus productivity in the resulting diagenetic stage reached for the three types of sapropels it appears that increased productivity is a prerequisite for sapropel formation but once organic matter is available in sufficient amounts variable efficiencies in bottom water ventilation are more important for modulating the diagenetic context in which different types of sapropels formed magnetic properties are more sensitive to variations in bottom water ventilation than to productivity and can be used to establish relative variations in bottom water ventilation both at and after periods of sapropel formation magnetic results and the distribution and type of sapropels at odp site 966 eratosthenes seamount between 2 3 and 4 0 ma suggest that bottom water ventilation was modulated by the orbital eccentricity component with ventilation being restricted during 400 kyr eccentricity maxima and enhanced during eccentricity minima enhanced ventilation during eccentricity minima as indicated by magnetic data is consistent with the occurrence of red intervals at site 966 and at other eastern mediterranean sites drilled during odp leg 160 and also with astronomically modulated variations in caco3 content found in mediterranean land sections this suggests that variations in bottom water ventilation modulated by 400 kyr eccentricity cycles operated at a basin wide scale

paleoseismology of the north anatolian fault at guzelkoy ganos segment turkey size and recurrence time of earthquake ruptures west of the sea of marmara 1 the ganos fault is the westernmost segment of the north anatolian fault that experienced the mw 7 4 earthquake of 9 august 1912 the earthquake revealed 45 km long of surface ruptures inland trending n70 e and 5 5 m of maximum right lateral offset near guzelkoy the long term deformation of the fault is clearly expressed by several pull apart basins and sag ponds pressure and shutter ridges and offset streams in parallel with detailed geomorphologic investigations we measured co seismic and cumulative displacements along the fault and selected the guzelkoy site for paleoseismology a microtopographic survey at the site yields 10 5 0 5 m and 35 4 1 5 m cumulative lateral offsets of stream channels and geomorphologic features seven paleoseismic parallel and cross fault trenches document successive faulting events and provide the timing of past earthquakes on the ganos fault segment radiocarbon dating of successive colluvial wedges in trench t1 and the fresh scarplet above probably 1912 surface rupture indicate the occurrence of three faulting events since the 14th century parallel trenches 3 5 6 and 7 expose paleo channels and show a cumulative right lateral offset of 16 5 1 5 m next to the fault and 21 3 1 5 m total channel deflection radiocarbon dating of past channel units and fault scarp related colluvial deposits imply an average 17 5 mm year slip rate and 323 142 years recurrence interval of large earthquakes during the last 1000 years on the ganos fault the succession of past faulting events and inferred slip rate west of the marmara sea provide more constraint on the long term faulting behavior in the seismic gap of the north anatolian fault and may contribute to a better seismic hazard assessment in the istanbul region

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

submarine earthquake geology along the north anatolia fault in the marmara sea turkey a model for transform basin sedimentation abstract the submerged portions of the north anatolia fault system beneath the marmara sea were studied with high resolution multibeam bathymetry subbottom profiling and sediment cores the major objectives were to learn about the seismic and tectonic history of the fault from the stratigraphic record at a scale similar to paleoseismic studies on land and to develop tools for submarine earthquake geology that can be applied to fault controlled basins in general we focused on holocene sediment in several marmara sea basins of different sizes the approach was to test whether 1 the depocenters of the larger basins contain a record of all historic ms 7 earthquakes within the marmara sea region 2 the small transform basins record earthquakes that rupture through them 3 vertical and strike slip holocene deformation can be quantified and 4 the effects of an earthquake generally includes both primary structural features due to rupture of the sea floor such as strata offset scarps and tilting as well as secondary effects due to shaking such as mass wasting and gravitational flows we found evidence of earthquakes that we correlate with historic events in 181 ad 740 ad 1063 ad 1343 ad 1509 ad 1766 ad 1894 ad and 1912 ad the geologic evidence is primarily from those basins adjacent to the rupture as inferred from historic data this suggests that coseismic deformation of the sea floor along the rupture is a critical factor in the sedimentary record we propose a qualitative sedimentation model that relates this coseismic deformation to mass wasting of the slope scour of the basin floor seiche motions and homogenite deposition frequent earthquake activity sheds sediments from the flanks contributes to the much thicker sediment on the basin floor and decreases the likelihood of sediment failures in response to normal marine gravity driven processes the surveying techniques and approaches used have therefore the potential of documenting earthquake ruptures of fault segments and to extend the earthquake record far before the known history thus improving hazard evaluations and the fundamental understanding of earthquake process

the eepas forecasting model and the probability of moderate to large earthquakes in central japan abstract the eepas every earthquake a precursor according to scale model is a space time point process model based on the precursory scale increase phenomenon and associated predictive scaling relations it has previously been fitted to the new zealand earthquake catalogue and applied successfully in quasi prospective tests on the cnss catalogue for california for forecasting earthquakes with magnitudes above 5 75 and on the jma catalogue of japan for magnitudes above 6 75 here we test whether the scaling relations extend to lower magnitudes by applying eepas to depth restricted subsets of the nied catalogue of the kanto area central japan for magnitudes above 4 75 as in previous studies the eepas model is found to be more informative than a quasi static baseline model based on proximity to past earthquakes and much more informative than the stationary uniform poisson model the information that it provides is illustrated by maps of the earthquake occurrence rate density covering magnitudes from 5 0 to 8 0 for the central japan region as at the beginning of year 2004 using the nied and jma catalogues to mid 2003

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

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

sedimentary features of seismoturbidites triggered by the 1983 and older historical earthquakes in the eastern margin of the japan sea abstract both mass failure deposits and turbidites are widely distributed in the epicentral area of the 1983 earthquake mw 7 9 in the eastern margin of the japan sea this basin is semi enclosed with no active conduits for the entrance of coarse detrital sediments seismic reflection surveys and sediment cores reveal that mass failure deposits which are distributed on the continental slopes merge into turbidites in the basin plain hence the mass wasting process is a major transportation process in this region one gravity core gh93 816 was recovered from the southeastern margin of the japan basin close to the epicentral area of the 1983 japan sea earthquake sedimentological results show that five turbidite beds are intercalated in the top 68 cm of the column occurrence of the b tm tephra at the depth of 68 71 cm indicates that these turbidite beds were developed during the last 1000 years the high 137cs concentration in the top 20 cm of the core implies that the uppermost turbidite bed was deposited after 1954 based on these age limits for the top and the bottom of the studied interval we estimate the recurrence intervals of turbidites as 160 330 years we suggest that these turbidites were generated by submarine slides which were triggered by the 1983 and older historical earthquakes in this region these seismoturbidites are characterized by amalgamated beds irregular structure sequences grain size breaks fluctuations abrupt changes in composition within bed and variable composition among beds from these features we infer that deposition resulted from a series of turbidity currents associated with multiple or line sources for example multiple shallow slides that were regionally initiated by the same earthquake the sedimentary features described herein may be useful as criteria for identifying modern seismoturbidites in other settings as well as seismoturbidites in the geologic record however further study is needed for the distinction of this type of turbidites from other types e g tempestites reflected turbidites

bromine counts from xrf scanning as an estimate of the marine organic carbon content of sediment cores 1 xrf sediment core scanning technology is increasingly used to quantify sediment composition the overall good correlation between biophilic halogen bromine br and sedimentary total organic carbon toc potentially allows the fast estimation of down core toc profiles by xrf scanning in order to test this approach we present data from the arabian sea and a mediterranean brine basin comparing xrf core scanning br data with discrete sample toc analyses overall br counts and toc show a clear correlation except when stable carbon isotope and c n data indicate intervals characterized by enhanced input of terrestrial organic matter hence solid phase br is exclusively associated with marine organic matter moc and can be used as a direct estimate of this parameter after a calibration is established high pore water br in the brine core steepens the br toc correlation but after salt correction shows a nearly identical gradient to that of the arabian sea core

astronomical forcing in late eocene marine sediments we use an x ray fluorescence xrf core scanner to obtain records of elemental concentrations in sediment cores from ocean drilling program odp leg 171b site 1052 blake nose atlantic margin of northern florida this record spans the middle to late eocene as indicated by bio and magnetostratigraphy and displays cyclicity that can be attributed to the orbital forcing of a combination of climate ocean circulation or productivity we use the xrf counts of iron and calcium as a proxy of the relative contribution from calcium carbonate and terrestrial material to construct a new composite depth record this new composite depth record provides the basis to extend the astronomically calibrated geological time scale into the middle eocene and results in revised estimates for the age and duration of magnetochrons c16 through c18 in addition we find an apparent change in the dominance of orbitally driven changes in obliquity and climatic precession at around 36 7 ma on our new time scale long term amplitude modulation patterns of eccentricity and obliquity in the data do not seem to match the current astronomical model any more suggesting the possibility of new constraints on astronomical calculations

evaluating climate change by multivariate statistical techniques on magnetic and chemical properties of marine sediments azores region regression models and cluster analyses are used to link magnetic properties of late pleistocene deep sea sediments in the azores area mid atlantic ocean with the chemical element composition the influence of the volcanic azores archipelago on sedimentation is evident in high magnetic mineral concentrations low field magnetic susceptibilities between 30 and 250 10 5 si and high ti al ratios n0 1 variations in magnetic mineral concentration and ti al ratios can be linked to detrital input and coincide with oxygen isotope ratio d 18 o changes the highest magnetic mineral concentrations and ti al ratios are found around temperate climate periods suggesting that detrital input from the azores islands is most prominent during these periods lower ti al ratios and a slightly different composition of the lithogenic fraction suggests the presence of a second probably eolian detrital component during glacial periods higher ba al ratios and dexcess bat estimates suggest higher productivity during the cold climate periods especially at the end of stages 2 and 6 temperate climate periods are characterised by a succession of peaks in magnetic mineral concentration and ti al ratios at the beginning of these periods followed by peaks in caco3 and mn al toward the end cluster analysis shows that the first peaks might be related to volcanic material which was initially deposited on land during eruptions in glacials and then washed into the sea due to the sea level rise at the beginning of temperate periods the latter peaks represent a more biogenic sediment signal which might be more diagnostic of vegetation changes in the azores archipelago due to a warmer climate d 2004 elsevier b v all rights reserved

comparative performance of time invariant long range and short range forecasting models on the earthquake catalogue of greece 1 time invariant long range and short range forecasting models were fitted to the earthquake catalogue of greece for magnitudes 4 0 and greater to optimize their ability to forecast events of magnitude 6 0 and greater in the period 1966 1980 the models considered were stationary spatially uniform and spatially varying poisson models a long range forecasting model based on the precursory scale increase phenomenon with every earthquake regarded as a precursor according to scale and epidemic type short range forecasting models with spatially uniform and spatially varying spontaneous seismicity each of the models was then applied to the catalogue for 1981 2002 and their forecasting performance was compared using the log likelihood statistic the long range forecasting model performed substantially better than the time invariant models and the short range forecasting models performed substantially better again the results show that the information value to be gained from modeling temporal and spatial variation of earthquake occurrence rate at both long and short range is much greater than can be gained from modeling spatial variation alone

steady late quaternary slip rate on the cinarcik section of the north anatolian fault near istanbul turkey the distribution of plate motion between multiple fault strands and how this distribution may evolve remain poorly understood despite the key implications for seismic hazards the north anatolian fault in northwest turkey is a prime example of a multistranded continental transform here we present the first constraints on late quaternary slip rates on its northern branch across the cinarcik basin in the eastern marmara sea we use both deep penetration and high resolution multichannel seismic reflection data with a stratigraphic age model to show that a depocenter has persisted near the fault bend responsible for that transform basin successively older depocenters have been transported westward by fault motion relative to eurasia indicating a uniform right lateral slip rate of 18 5 mm yr over the last 500 000 years compared to overall gps rates 23 24 mm yr thus the northern branch has slipped at a nearly constant rate and has accounted for most of the relative plate motion between eurasia and anatolia since 0 5 ma

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

sedimentary earthquake records in the izmit gulf sea of marmara turkey abstract sedimentary earthquake records of the last 2400 a including that of the devastating 17 august 1999 izmit earthquake mw 7 4 were studied in cores from the 210 m deep central karamursel basin of the izmit gulf in the eastern sea of marmara using laser grain size physical properties stable o and c isotopes and xrf core scanner analyses and dated by radionuclide and radiocarbon methods the earthquake records are represented by turbidite homogenite mass flow units thu that commonly contain a basal coarse layer a middle laminated silt layer and an overlying homogeneous mud layer the coarse basal part has a sharp and sometimes scoured lower boundary and includes multiple coarse sand silt layers or laminae showing normal size grading multiple coarse layers and occasional bi directional cross bedding suggest deposition from a bed load during water column oscillations or seiche effect the grain size characteristics of the overlaying laminated silt and the homogeneous mud units indicate deposition from weak oscillating currents and homogeneous suspension respectively high mn value just below the base of thus suggests diagenetic enrichment at oxic anoxic redox boundary before the mass flow event sharp decrease in mn with very low values within the thus suggests transient redox conditions following the mass flow variable geochemical compositions of the basal coarse layers indicate different sediment sources for different thus eight sedimentary earthquake records observed in the last 2400 a in the izmit gulf can be confidently correlated with the historical earthquakes of 1999 1509 ad ms 7 2 1296 ad i vii 865 ad i viii 740 ad i viii 268 ad i viii 358 ad i ix and 427 bc this gives an earthquake recurrence time of ca 300 a with the interval between consecutive events ranging from 90 to 695 a

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

improving geomagnetic field reconstructions for 0 3 ka global geomagnetic field reconstructions on millennial time scales can be based on comprehensive paleomagnetic data compilations but especially for older data these still suffer from limitations in data quality and age controls as well as poor temporal and spatial coverage here we present updated global models for the time interval 0 3 ka where additions to the data basis mainly impact the south east asian alaskan and siberian regions we summarize recent progress in millennial scale modelling documenting the cumulative results from incremental modifications to the standard algorithms used to produce regularized time varying spherical harmonic models spanning 1000 bc to 1990 ad from 1590 to 1990 ad gauss coefficients from the historical gufm1 model supplement the paleomagnetic information in addition to absolute paleointensities calibrated relative paleointensity data from sediments are now routinely included iterative data rejection and recalibration of relative intensity records from sediments ensure stable results bootstrap experiments to generate uncertainty estimates for the model take account of uncertainties in both age and magnetic elements and additionally assess the impact of sampling in both time and space based on averaged results from bootstrap experiments taking account of data and age uncertainties we distinguish more conservative model estimates cals3k nb representing robust field structure at the core mantle boundary from relatively high resolution models cals3k n for model versions n 3 and 4 we assess the impact of newly available data and modifications to the modelling method by comparing the previous cals3k 3 the new cals3k 4 and the conservative new model cals3k 4b we conclude that with presently available data it is not feasible to produce a model that is equally suitable for relatively high resolution field predictions at earth s surface and robust reconstruction of field evolution avoiding spurious structure at the core mantle boundary cmb we presently consider cals3k 4 the best high resolution model and recommend the more conservative lower resolution version for studies of field evolution at the cmb

statistical model for standard seismicity and detection of anomalies by residual analysis abstract a statistical point process model is derived to describe the standard activity of earthquake occurrences by assuming that general seismicity is given by the superposition of aftershock sequences the parameters are estimated ty the maximum likelihood method using the estimated model the residual point process of the data is defined and used to find the anomalies which are included in the data set but not captured in the considered model for the standard seismicity for instance seismic quiescences can be measured quantitatively by using the residual process some examples are provided to illustrate such analyses furthermore a time series of the magnitudes on the residual point process is considered to investigate its dependence either on the time or on the history of the seismicity by assuming the exponential distribution at each time and modelling of the b value we can examine such dependences and estimate them two practical examples are shown

sedimentary record of late holocene seismicity and uplift of hersek restraining bend along the north anatolian fault in the gulf of izmit abstract the north anatolian fault naf in the gulf of izmit eastern marmara sea consists of three subsegments linked by bends the present study focuses on the hersek peninsula which is a ridge of pleistocene and holocene deposits emerged by tectonic uplift at a left stepping 7 restraining double bend between the karamursel and darica segments of the naf the hersek bend has acted as a local barrier to westward rupture propagation whereby the marine substrate was deformed by transpressional thrusting combined with underwater slumping the record of the hersek ridge emergence has been analyzed in excavation trenches by the methods of sedimentology geomorphology and radiocarbon dating the time of initial emergence is unknown but the highest recognized palaeoshoreline terrace indicates that around 2250 yrs bc a narrow ridge was already standing at least 13 m above the sea level the uplift rate of the ridge is about 3 5 m kyr for the past 4250 years the development of the three lower lying successively younger palaeoshoreline terraces involved episodes of uplift accompanied and or followed by tsunami events the ridge s stepwise uplift above the sea level amounted to at least 28 m on the basis of radiocarbon dates the deciphered seismotectonic events have been tentatively correlated to the region s historical earthquakes which allowed the fault bend s behavior to be reconstructed and time constrained the study gives new insights into the dynamics of an naf restraining bend and the non characteristic behavior of the naf segments in the quake stricken region of eastern marmara sea

late holocene erosion in nw anatolia from sediments of lake manyas lake ulubat and the southern shelf of the marmara sea turkey abstract this paper deals with modern and ancient sedimentation in fresh water lakes and the marine shelf of the southern marmara region nw anatolia turkey most of the information has been obtained from monitoring of suspended load discharged into two lakes manyas and ulubat in the last 45 years and from 8 to 11 m thick lacustrine sediments in addition to radiocarbon dated shelf sediments this allows a holistic approach to the drainage basin denudation over time the results show that the sedimentation rates in the lakes were low 0 22 cm year 1 from 4000 to 2000 years bp and then they increased 0 29 cm year 1 up to sub recent times and reached 0 44 cm year 1 in the last century it is suggested that deforestation created high rates of sedimentation in the basins and or strong denudation of the region during the late holocene this study also shows that for shallow freshwater lakes the calculation of sedimentation rates must include fine particles lost by the outlets and coarse grained bed load deposited on their shores in addition a high rate of sedimentation has been created by short but repetitive intense depositions during the last century particularly during the last 45 years the rate of sedimentation or denudation has increased dramatically in nw turkey the two world wars and mismanagement of the land had important local effects by increasing deforestation and resulting in the present erosive conditions

offshore sedimentary effects of the 12 january 2010 haiti earthquake although the 12 january 2010 haiti earthquake was one of the deadliest earthquakes in history it left no clear geological evidence of rupture on land as a tectonic event the earthquake was complex even the faults involved remain unclear using geophysical and coring data we document direct evidence of the sedimentation generated by the catastrophic 12 january 2010 earthquake offshore these studies document submarine paleoseismology methods that can be used for assessing seismic risk in this and other tectonic settings such as the california san andreas fault where deeper buried blind thrusts may exist shaking by the 12 january main shock triggered sediment failures and turbidity currents from coastal sources to deep water sinks an 0 05 km 3 turbidite was deposited in the canal du sud basin 1750 m water depth over 50 km 2 almost 2 months after the main shock a 600 m thick sediment plume was still present in the lowermost water column at this location the turbidite was time correlated to the 12 january earthquake by the excess 234 th in the sediments with a half life of 24 days its presence documents an infl ux of terrigenous sediment mixing with marine sources derived from the basin slopes this turbidite and older ones observed beneath it displays complex cross bedded and fi ning upward stratigraphy indicative of long waves and seiche oscillations that are consistent with locally reported tsunamis this 12 january sedimentary record highlights the potential for submarine paleoseismology to unravel the seismic history of continental transform boundaries such as the enriquillo plantain garden fault in the dominican republic haiti and jamaica as well as other tectonic settings where no clear land based evidence for a rupture exists

probabilistic seismic hazard estimation in low seismicity regions considering non poissonian seismic occurrence summary in low seismicity regions such as france or germany the estimation of probabilistic seismic hazard must cope with the difficult identification of active faults and with the low amount of seismic data available since the probabilistic hazard method was initiated most studies assume a poissonian occurrence of earthquakes here we propose a method that enables the inclusion of time and space dependences between earthquakes into the probabilistic estimation of hazard combining the seismicity model epidemic type aftershocks sequence etas with a monte carlo technique aftershocks are naturally accounted for in the hazard determination the method is applied to the pyrenees region in southern france the impact on hazard of declustering and of the usual assumption that earthquakes occur according to a poisson process is quantified showing that aftershocks contribute on average less than 5 per cent to the probabilistic hazard with an upper bound around 18 per cent

a new seismic hazard model for new zealand we present a new probabilistic seismic hazard analysis psha for new zealand an important feature of the analysis is the application of a new method for the treatment of historical distributed seismicity data in psha the psha uses the seismicity recorded across and beneath the country to define a three dimensional grid of a values i e parameter a of a gutenberg richter distribution log n yr a bm in which n yr is the number of earthquakes per year recorded inside each grid cell equal to or greater than magnitude m parameter b and the limiting maximum cutoff magnitude of the gutenberg richter distribution are defined from the surrounding region 14 crustal and 23 subcrustal seismotectonic zones are defined for the country and then smoothed across the boundaries of the zones the methodology therefore combines the modern method of defining continuous distributions of seismicity parameters frankel 1995 frankel et al 1996 with the traditional method of defining large area sources and the associated seismicity parameters e g algermissen et al 1990 the methodology provides a means of including deep subduction zone seismicity in a psha preserves the finer scale spatial variations of seismicity rates across a region avoids the undesirable edge effects produced in the traditional method when adjacent area sources enclose areas of significantly different seismicity rates and also enables parameters most reliably defined at a regional scale parameter b and maximum cutoff magnitude of a gutenberg richter distribution and slip type to be incorporated into the psha the psha combines the modeled seismicity data with geological data describing the location and earthquake recurrence behavior of 305 active faults and new attenuation relationships for peak ground acceleration and spectral acceleration developed specifically for new zealand different attenuation expressions are used for crustal and subduction zone earthquakes the resulting psh maps for a 150 year return period show the highest hazard to occur in the center and southwest of the country in the areas of highest historical crustal and deep subduction zone seismicity in contrast the longer return period maps 475 and 1000 year return period show the highest hazard to occur from the southwest to northeast ends of the country along the faults that accommodate the majority of the motion between the pacific and australian plates the maps are currently being used to revise new zealand s building code which has previously been based on pshas that did not explicitly include individual faults as earthquake sources manuscript received 10 april 2001

hydrology in the sea of marmara during the last 23 ka implications for timing of black sea connections and sapropel deposition 1 sediments deposited under lacustrine and marine conditions in the sea of marmara hold a late quaternary record for water exchange between the black sea and the mediterranean sea here we report a multiproxy data set based on oxygen and strontium isotope results obtained from carbonate shells major and trace elements and specific organic biomarker measurements as well as a micropaleontological study from a 14c dated sediment core retrieved from the sea of marmara pronounced changes occurred in 18o and 87sr 86sr values at the fresh and marine water transition providing additional information in relation to micropaleontological data organic biomarker concentrations documented the marine origin of the sapropelic layer while changes in n alkane concentrations clearly indicated an enhanced contribution for organic matter of terrestrial origin before and after the event when compared with the black sea record the results suggest that the black sea was outflowing to the sea of marmara from the last glacial maximum until the warmer bolling allerod the first marine incursion in the sea of marmara occurred at 14 7 cal ka b p however salinification of the basin was gradual indicating that black sea freshwaters were still contributing to the marmara seawater budget after the younger dryas which is associated with a high input of organic matter of terrestrial origin both basins were disconnected resulting in a salinity increase in the sea of marmara the deposition of organic rich sapropel that followed was mainly related to enhanced primary productivity characterized by a reorganization of the phytoplankton population

paleomagnetic and geochemical record from cores from the sea of marmara turkey age constraints and implications of sapropelic deposition on early diagenesis abstract we present results of a multi proxy analysis of two sediment cores from the marmara sea the cores were analyzed using paleomagnetic and geochemical measurements two sapropels are documented in the last 11 kyr and are recorded in several locations across the marmara sea these two sapropels have contrasting magnetic properties the magnetic record is affected by intense early diagenesis the most recent upper sapropelic layer has low remanence and susceptibility values a record of paleomagnetic inclinations could still be isolated above the diagenesis front and is compared with secular variation models the lower sapropel is identified in the deep part of the oldest studied core klg07 and has distinct magnetic properties characterized by high remanence and susceptibility values using the magnetic properties it is possible to constrain bottom water ventilation and reconnection episodes between the marmara sea and the black sea following the sea level rise during the last glacial to inter glacial transition

test of the eepas forecasting model on the japan earthquake catalogue the eepas every earthquake a precursor according to scale model is a method of forecasting earthquakes based on the notion that the precursory scale increase phenomenon occurs at all scales in the seismogenic process the rate density of future earthquake occurrence is computed directly from past earthquakes in the catalogue the eepas model has previously been fitted to the new zealand earthquake catalogue and successfully tested on the california catalogue

tsunami hazard in the marmara sea turkey a numerical approach to discuss active faulting and impact on the istanbul coastal areas abstract the westward propagation of the seismic ruptures along the north anatolian fault naf during the 20th century has increased the probability that the next rupture will be located offshore in the marmara sea in the prolongation of the 1999 izmit earthquake faulting historical tsunamis have been evidenced in the marmara sea e g those associated with the 1509 may 1766 strong earthquakes that broke submarine parts of the naf in the vicinity of istanbul and future submarine events are expected to produce tsunamis as well that could be triggered either by submarine coseismic displacements or by landsliding the assessment of their amplitude and extent of their effects is discussed in this paper through numerical modeling based on both earthquake and landsliding sources we use a finite difference method that yields the maximum water levels reached in the marmara sea and the effects run up values around the coasts of istanbul using a set of three nested bathymetric grids with a decreasing cell size to focus on istanbul first we consider probable earthquake sources along the northern branch of the emerged naf namely in the eastern cinarcik basin magnitude mw 7 2 in the western tekirdag and central basins magnitude mw 7 5 and along the whole branch magnitude mw 7 6 the impact obtained in istanbul is all the more important as a normal component in the eastern basin is present and maximum water levels can reach 2 m along the shoreline provoking locally significant inundations these results show that the historical tsunami observations around istanbul 1509 may 1766 provided they are directly due to earthquake sources imply a significant normal component in the eastern basin whatever the extent of the rupture westward conversely a source located in the western and or central basin does not provoke large waves in istanbul e g august 1766 most probably finally we test three landslide sources in the southern vicinity of istanbul and show that the damage is expected to be larger than in the case of earthquake sources for moderate to large volumes involved this kind of source in addition to the coseismic deformation could therefore be a good candidate to explain the historical waves in istanbul especially in 1509 where run up values as high as 6 m have been reported provided we are confident in the historical documents available

seismic triggering of landslides and turbidity currents offshore portugal 1 sediments in deep water basins often include turbidites that record sediment input from adjacent continental margins in seismically active areas where turbidity currents are triggered by earthquakes the basinal turbidite sequence may thus contain a record of palaeoseismicity which can be used to infer the frequency of earthquakes affecting the margins of the basin this is particularly useful where large earthquakes have a recurrence interval than is greater than the historical record however turbidity currents can be triggered by several processes and it is often difficult to trace individual turbidites to their precise source areas and to assign a definite trigger to a particular turbidite here we demonstrate that turbidites emplaced at 6600 and 8300 cal yr bp in the tagus abyssal plain off portugal correlate with erosional hiatuses in two submarine canyons on the continental margin the turbidites are sourced from simultaneous landsliding in both canyons requiring regional triggers interpreted as earthquakes an earthquake recurrence interval for the continental margin of 4000 years is estimated by extrapolation to deeper turbidites in the basin sequence however the example of the 1755 earthquake which caused widespread devastation in southwest iberia shows that palaeoseismic interpretations must be made with caution the 1755 earthquake had a magnitude 8 5 and yet the associated turbidite in the abyssal plain is typically 5 cm thick while older turbidites can be 1 m thick given the large 1755 earthquake magnitude the difference in turbidite thickness is unlikely to be related to the relative size of triggering earthquakes instead we suggest that the offshore location of the 1755 earthquake coupled with low sedimentation rates during the holocene may have limited the size of the associated turbidite

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

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

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