linkages between turbidites in the southern okinawa trough and submarine earthquakes 1 turbidite layers in surficial 6 8 submarine earthquakes recorded in the region since the 20th century the repeating pattern of turbidite layers reported here on decadal to centennial time scales suggests what may be the long term rhythm of seismic activities at this tectonically active plate boundary index terms 0932 exploration geophysics radioactivity methods 1035 geochemistry geochronology 3022 marine geology and geophysics marine sediments processes and transport 3025 marine geology and geophysics marine seismics 0935 7221 seismology paleoseismology citation huh c a c c su w t liang and c y ling 2004 linkages between turbidites in the southern okinawa trough and submarine earthquakes geophys res lett 31 l12304 doi 10 1029 2004gl019731

the role of earthquakes in inducing sediment mass movements in the eastern korinthiakos gulf an example from the february 24 march 4 1981 activity abstract korinthiakos gulf is a narrow arm of the sea connecting the ionian and the aegean seas through the rion antirion strait and the korinth canal respectively the eastern part of korinthiakos was surveyed by the marine geology department of the institute of geology and mineral exploration of greece using a 3 5 khz subbottom profiler the survey was carried out a short time after intensive earthquake activity which occurred in the area from february 24 to march 4 1981 during this activity three major shocks of magnitudes ranging from 6 4 to 6 7 took place the subbottom profiles reveal a sediment mass which was deposited by submarine slumping in the alkyonides basin which lies at the eastern end of the studied area the slump is about 10 km long 1 5 to 2 0 km wide and its areal extent is about 16 km2 the scarp area occurs at a bathymetric depth of about 100 to 250 m in the northeastern part of the basin the scarp faces are from 10 to 15 m high and have a total areal extent of about 4 km2 the destruction of fishing nets of trawling boats and other evidence indicates that the triggering of the mass flow was effected by the earthquake activity and probably by the first major shock scarp areas and scarp faces from which sediment masses have been removed were detected in other shallow and deep sectors of the studied area indicating that mass transport processes are very common in this area of high seismicity

seismicity deformation and seismic hazard in the western rift of corinth new insights from the corinth rift laboratory crl this paper presents the main recent results obtained by the seismological and geophysical monitoring arrays in operation in the rift of corinth greece the corinth rift laboratory crl is set up near the western end of the rift where instrumental seismicity and strain rate is highest the seismicity is clustered between 5 and 10 km defining an active layer gently dipping north on which the main normal faults mostly dipping north are rooting it may be interpreted as a detachment zone possibly related to the phyllade thrust nappe young active normal faults connecting the aigion to the psathopyrgos faults seem to control the spatial distribution of the microseismicity this seismic activity is interpreted as a seismic creep from gps measurements which shows evidence for fast continuous slip on the deepest part on the detachment zone offshore either the shallowest part of the faults is creeping or the strain is relaxed in the shallow sediments as inferred from the large ns strain gradient reported by gps the predicted subsidence of the central part of the rift is well fitted by the new continuous gps measurements the location of shallow earthquakes between 5 and 3 5 km in depth recorded on the on shore helike and aigion faults are compatible with 50 and 60 mean dip angles respectively the offshore faults also show indirect evidence for high dip angles this strongly differs from the low dip values reported for active faults more to the east of the rift suggesting a significant structural or rheological change possibly related to the hypothetical presence of the phyllade nappe large seismic swarms lasting weeks to months seem to activate recent synrift as well as pre rift faults most of the faults of the investigated area are in their latest part of cycle so that the probability of at least one moderate to large earthquake m 6 to 6 7 is very high within a few decades furthermore the region west to aigion is likely to be in an accelerated state of extension possibly 2 to 3 times its mean interseismic value high resolution strain measurement with a borehole dilatometer and long base hydrostatic tiltmeters started end of 2002 a transient strain has

seismicity normal faulting and the geomorphological development of the gulf of corinth greece the corinth earthquakes of february and march 1981 three major destructive earthquakes of m s 6 7 6 4 6 4 occurred in the eastern part of the gulf of corinth in february and march 1981 associated normal faulting was observed on both the north and the south sides of the gulf examination of teleseismic local seismic surface faulting and geomorpbological data suggests that the first and second of these shocks activated major north dipping normal faults these faults control the topography and bathymetry and are related to the recent uplift and subsidence of the coastline it is probable that the first earthquake occurred on a faultwhich outcrops underwater and the second on a fault which is visible on land it appears that the third shock activated an antithetic normal fault dipping southwards on the north side of the gulf and that the overall structure of the gulf of corinth graben is asymmetric the northern antithetic fault clearly demonstrates the geomorphological changes associated with developing young normal faulting in addition we suggest that observations of recent coastline movement provide a powerful tool for identifying major active fault systems and predicting their historical role in the paleogeography of an area

earthquake induced clastic dikes detected by anisotropy of magnetic susceptibility clastic dikes form either by passive deposition of clastic material into preexisting fissures or by fracturing and injection of clastic material during seismic shaking or passive overpressure because of their similar final geometry the origin of clastic dikes is commonly ambiguous we studied the mechanisms of clastic dike formation within the seismically active dead sea basin where hundreds of clastic dikes crosscut soft rock of the late pleistocene lacustrine lisan formation we analyzed the anisotropy of magnetic susceptibility ams of clastic dikes of known origin and defined characteristic ams signatures of depositional or injection filling we discovered that passively filled dikes which contain brownish silt resembling local surface sediments are characterized by an oblate ams ellipsoid and vertical minimum susceptibility axis v3 dikes that contain green clayey sediment connected to a mineralogically identical detrital layer of the lisan formation are characterized by a triaxial ams ellipsoid well grouped subhorizontal and parallel to the dike walls maximum susceptibility axis v1 and subvertical intermediate susceptibility axis v2 field evidence and ams analysis indicate that most of these dikes were emplaced by injection inferred to be due to seismically triggered fluidization this novel application of the ams provides a petrofabric tool for distinguishing passively filled dikes from injection dikes and where appropriate for identifying the latter as seismites

the late pleistocene palaeoclimatic record of north atlantic deep sea sediments revealed by mineral magnetic measurements eight cores of north atlantic deep sea sediment are correlated using simple rapid and non destructive measurements of magnetic susceptibility and isothermal remanence this stratigraphy is demonstrably related to late pleistocene palaeoclimatic variations by comparison with the oxygen isotope and microfossil records of these cores fluctuations in the concentration dependent magnetic properties of the cores largely reflect their lithological composition consisting of climatically modulated cycles of marl glacial horizons and nannofossil chalk interglacial horizons high magnetic concentration characterises glacial horizons which correspond to periods when carbonate productivity was severely restricted and ice rafted detrital inputs were prolific coincident with the migration south of the north atlantic polar front to within 3 of latitude north of the coring site in contrast interglacial horizons are characterised by low magnetic concentration and high carbonate content of the sediment consequent on the retreat of the polar front and the re establishment of coccolith floras in its wake during these periods ratios formed between individual magnetic parameters are independent of magnetic concentration and are thus free of any climatic influences wrought by carbonate oscillations in this study however such ratios exhibit a definite response to palaeoclimatic variations attributable to differences in the composition and grain size of the magnetic mineral assemblage of glacial vis a vis interglacial horizons of the cores these differences in mineral magnetic composition are substantially confirmed by mossbauer effect studies of selected samples representing peak glacial and interglacial horizons of one core such glacial interglacial contrasts in the concentration mineralogy and grain size of the magnetic assemblage most probably result from variations in the source and flux density of detritral inputs induced by changes in climate x ray diffraction studies of the same core indicate that variations in the mineralogy of the detrital fraction of the sediment are consistent with those of the magnetic assemblage together these data point to the conclusion that a subsidiary low latitude possibly aeolian detrital flux supplements high latitude ice rafted input in glacial horizons of the cores the low latitude flux however is also identifiable in interglacial horizons independent evidence suggests that this low latitude aeolian flux may be derived from the sahel region of north africa and transported to the coring site by harmattan winds associated with saharan dust outbreaks

thrust fault mechanics and origin of a frontal ramp several features of thrust sheets in nonmetamorphic and relatively low grade metamorphic terrains indicate that the modes of faulting included both gradual and stick slip types of motion a first order quantitative analysis is made of the mechanics of this type of faulting in the analysis part of a wedge shaped thrust belt slips forward over a fault area of length l and unit width w producing a strain concentration in subhorizontal strata at the front of the growing thrust where a frontal ramp develops by shear fracturing equations for net slip x and the conditions for ramping are evaluated with limit equilibrium principles and coupled oscillator theory the quantitative analysis takes into account anisotropy resulting from contrasts in competency and facies changes a special case solution for maximum net slip associated with stick slip is lw ki 1 cos ot o 12 1 cos 1t where is the stress drop ki are spring constants of the strata 0 and 1 are natural frequencies of the system and t evaluated from another equation is the time for net slip the spring constants and natural frequencies can be evaluated from seismic and stratigraphic data a preliminary solution for piggy back thrusting indicates that ramp spacing can be systematic and that it depends upon the thickness of the deforming package the elastic parameters of the deforming package the slope of the topographic surface and the stresses along the trailing edge of the package

structural discordance between neogene detachments and frontal sevier thrusts central mormon mountains southern nevada detailed geologic mapping in the mormon mountains of southern nevada provides significant insight into processes of extensional tectonics developed within older compressional orogens a newly discovered wsw directed low angle normal fault the mormon peak detachment juxtaposes the highest levels of the frontal most part of the east vergent mesozoic sevier thrust belt with autochthonous crystalline basement palinspastic analysis suggests that the detachment initially dipped 20 25 to the west and cut discordantly across thrust faults nearly complete lateral removal of the hanging wall from the area has exposed a 5 km thick longitudinal cross section through the thrust belt in the footwall while highly attenuated remnants of the hanging wall nowhere more than a few hundred meters thick structurally veneer the range the present arched configuration of the detachment resulted in part from progressive domino style rotation of a few degrees while it was active but is largely due to rotation on younger structurally lower basement penetrating normal faults that initiated at high angle the geometry and kinematics of normal faulting in the mormon mountains suggest that pre existing thrust planes are not required for the initiation of low angle normal faults and even where closely overlapped by extensional tectonism need not function as a primary control of detachment geometry caution must thus be exercised in interpreting low angle normal faults of uncertain tectonic heritage such as those seen in the cocorp west central utah and birp s moist deep reflection profiles although thrust fault reactivation has reasonably been shown to be the origin of a very few low angle normal faults our results indicate that it may not be as fundamental a component of orogenic architecture as it is now widely perceived to be we conclude that while in many instances thrust fault reactivation may be both a plausible and attractive hypothesis it may never be assumed

characterization of the magnetic fabric of rocks abstract an inextensive system of magnetic susceptibility anisotropy factors is suggested which is sufficient in the majority of practical applications for characterizing the magnetic fabric of rocks the system involves three newly devised factors the corrected anisotropy degree the shape factor and the difference shape factor the first of these characterizes the quantity of anisotropy somewhat better than the commonly used anisotropy degree the shape factor characterizes the quality of anisotropy i e the shape of the susceptibility ellipsoid in a convenient way its definition is based on a certain analogy between the anisotropy ellipsoid and the strain ellipsoid the difference shape factor can replace the shape factor when only the differences between the principal susceptibilities are given while the mean susceptibility is unknown

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

similarities between recent seismic activity and paleoseismites during the late miocene in the external betic chain spain relationship by b value and the fractal dimension abstract a paleoseismic data set derived from the relationship between the thickness of seismites mixed layers in lacustrine miocene deposits and the magnitude of the earthquakes is presented the relationship between both parameters was calibrated by the threshold of fluidification limits in the interval of magnitude 5 and 5 5 the mixed layers deformational sediment structures due to seismic activity were observed in varved sediments from three neogene lacustrine basins near hellin albacete spain el cenajo elche de la sierra and hijar and are interpreted as liquefaction features due to seismic phenomena these paleoseismic structures were dated relative values by measurements of cyclic annual sedimentation in the varved sediments from these observations we are able to establish a recurrence interval of 130 years with events for magnitude bigger than or equal to four both paleoseismicity and instrumental seismicity data sets obey the gutenberg richter law and the b value is close to 0 86 the fractal dimension dimension of capacity of spatial distribution of potentially active faults faults oriented according to the stress tensor regime in the area was measured by the box counting technique d 0 1 73 according to the aki empirical relation d 0 2 b for the instrumental seismicity and paleoseismic data sets in the area the fractal dimension is close to 1 72 the similar value of the fractal dimension obtained by both techniques shows homogeneous seismic dynamics during the studied time interval moreover the better established b value of the paleoseismic data sets 0 86 compared with the b value for the incomplete historic seismicity

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

active faulting within the offshore western gulf of corinth greece implications for models of continental rift deformation discrimination between different lithospheric extension models focusing on the roles of low angle vs high angle faulting and how strain is distributed requires high fidelity imaging of brittle deformation high resolution seismic reflection and multibeam bathymetric data in the western gulf of corinth continental rift were collected to establish the contribution of offshore faults to extension onshore fault slip here is significantly less than expected from geodetic strain rates the rift at this location is a half graben tilted to the north by s dipping faults within the uppermost crust a basement horst on the northern margin is uplifted by the north and south eratini faults and the axial channel is fault controlled subsided lowstand shorelines in the hanging wall of the north eratini and the well studied aigion fault suggest that the faults have similar displacements summed extension from the four major faults across this part of the rift eliki subchannel south eratini north eratini is 8 16 mm yr thereby reconciling geologic and geodetic data sets distributed deformation across isolated multiple faults can model this part of the rift without recourse to and potentially incompatible with an underlying low angle detachment

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

hydrolytic weakening in olivine single crystals deformation experiments on single crystals of san carlos olivine under hydrous conditions were performed to investigate the microphysical processes responsible for hydrolytic weakening during dislocation creep hydrogen was supplied to the crystals using either talc or brucite sealed in nickel capsules with the crystal deformation experiments were carried out using a gas medium apparatus at temperatures of 1050 to 1250 c a confining pressure of 300 mpa differential stresses of 45 to 294 mpa and resultant strain rates of 1 5 10 6 to 4 4 10 4 s 1 for talc buffered i e water and orthopyroxene buffered samples at high temperatures the dependence of strain rate on stress follows a power law relationship with a stress exponent n of 2 5 and an activation energy of 490 kj mol brucite buffered samples deformed faster than talc buffered samples but contained similar hydrogen concentrations demonstrating that strain rate is influenced by orthopyroxene activity under hydrous conditions the values of n and dependence of strain rate on orthopyroxene activity are consistent with hydrolytic weakening occurring in the climb controlled dislocation creep regime that is associated with deformation controlled by lattice diffusion under hydrous conditions and by pipe diffusion under anhydrous conditions analyses of postdeformation electron backscatter diffraction data demonstrate that dislocations with 100 burgers vectors are dominant in the climb controlled regime and dislocations with 001 are dominant in the glide controlled regime comparison of the experimentally determined constitutive equations demonstrates that under hydrous conditions crystals deform 1 to 2 orders of magnitude faster than under anhydrous conditions

paleoearthquake deformations recorded by magnetic variables abstract faults and related deformational structures give evidence of earthquakes in the past the ground shaking at high magnitude seismic events usually generates liquefaction the higher seismic magnitude the larger area of liquefaction we can now demonstrate that it is possible to discriminate between plastic and liquefied deformations with magnetic methods besides it is possible to record internal crypto deformations not visibly observed this offers new means of recording past earthquakes fine particles carrying the magnetic remanence are shown to move rotate and re align with respect to the prevailing geomagnetic field direction or in response to the applied shaking forces we call this seismomagnetization this implies that paleoseismics may generate excursion like paleomagnetic signals despite the absence of visible deformation structures

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

tsunamis observed in greece and the surrounding area from antiquity up to the present times abstract a new and improved catalogue of tsunamis observed in greece and the surrounding area from antiquity up to the present time is presented reliable information derived from previous catalogues as well as original historical information which has not been previously taken into account has been used as data source as far as the associated earthquakes are concerned some recent and reliable seismological catalogues have been used as data sources the main cause of the generation of tsunamis is the shallow seismic activity that occurs along the hellenic arc as well as in the internal seismic zone of the aegean area the statistics for tsunamis indicate that the tsunami hazard is low considering the area in question as a whole ten distinct coastal regions in which this hazard can be suggested as medium or high have been defined

holocene earthquake record offshore portugal sw iberia testing turbidite paleoseismology in a slow convergence margin the sw margin of the iberian peninsula hosts the present day boundary between the eurasian and african plates convergence 4 5 mm yr is accommodated through a wide deformation zone characterized by moderate magnitude seismic activity this zone has also been the source of the most important seismic events in western europe such as the 1755 lisbon earthquake and tsunami and 1969 horseshoe earthquake despite efforts to identify active seismogenic structures in the gulf of cadiz in the last ten years little is known about its paleoseismic history the turbidite paleoseismology approach was applied for the first time in a low rate convergent margin to determine the recurrence interval of large earthquake events that occurred in sw iberia during the holocene four sediment cores collected at strategically located sites offshore portugal i e tagus abyssal plain infante don henrique basin and horseshoe abyssal plain reveal that these deep sea basins preserve a record of episodic deposition of turbidites in the sw iberian margin excluding special climatic events earthquakes are the most likely triggering mechanism for synchronous widely spaced distributed turbidites during the holocene when the sea level was relatively stable age correlation together with textural mineralogical physical properties and geochemical signatures of the new cores complemented by pre existing multicores and gravity cores reveals a total of 7 widespread turbidite events for the holocene precise dating of the most recent turbidite event e1 based on

tsunami induced sediment transport in the abyssal mediterranean sea an unusual stratigraphic unit nicknamed homogenite fills topographic lows in the complex ridge and trough bathymetry at two survey sites on the western mediterranean ridge and the calabrian ridge on near bottom 4 khz seismic reflection profiles this unit us an acoustically transparent near surface flat lying layer whereas in cores it is a homogeneous gray marl as much as 7 m thick grain size decreases upcore within the unit implying that it was deposited in a single event controlled by gravitational settling the stratigraphic position of the homogenite relative to a firmly dated sapropel bed suggests emplacement between 4400 and 3100 yr b p the source of the homogenite is inferred to be the nearby basin walls farther east two other sites with similar rugged topography lack homogenite entirely a triggering mechanism is required which is capable of initiating massive sediment transport simultaneously in many separate basins at the western two survey sites but which is not effective at the eastern sites a large archeologically recorded earthquake of the correct age is considered and rejected because its epicenter is closer to the nonhomogenite bearing sites than to the sites where this sediment type was observed and because several other earthquakes of comparable magnitude have since been recorded in the area whereas the homogenite is unique the 3 500 yr b p collapse of the caldera of the volcano of santorini caused a huge tsunami which is recorded archeologically and geologically around the eastern mediterranean because of refraction of the tsunami by the bathymetry and because the caldera collapsed in its southwest corner a disproportionate amount of tsunami energy was directed toward the western area where homogenite is observed in contrast the homogenite free sites were relatively sheltered an order of magnitude calculation shows that the near bottom oscillating currents accompanying the santorini tsunami were at or above the threshold erosion velocity at the homogenite bearing sites in addition the near bottom pressure pulse under the tsunami at the homogenite bearing sites was sufficient to cause liquefaction of sediments neither mechanism was adequate to cause sediment transport or slope failure at the homogenite free sites

thrusts in the eastern spring mountains nevada geometry and mechanical implications in the la madre mountain area paleozoic miogeosynclinal carbonate rocks have been transported eastward on two major thrust faults the keystone and red spring thrusts with an estimated minimum cumulative transport of 30 5 km the red spring thrust cuts upsection eastward in its upper plate the keystone thrust is exposed along a ramp of complex geometry and cuts upsection in its upper plate at its eastern end the character of upper and lower plate rocks suggests that high pore fluid pressure probably was not developed on either thrust terrigenous clastic sediments of middle triassic to jurassic or early cretaceous age crop out in the autochthon the youngest of these the synorogenic conglomerate of brownstone basin was deposited before and during the first major structural event the emplacement of the red spring plate above or near an erosional surface precambrian or early cambrian clasts in the conglomerate record the uplift of the structurally higher wheeler pass thrust plate before uplift of the red spring plate north to northwest trending high angle normal faults broke the red spring plate and parautochthon into northeast tilted blocks deep erosion followed the keystone plate was emplaced over these blocks renewed movement on the high angle faults displaced the keystone thrust deposition of a large 7 km 2 minimum landslide breccia postdated these high angle fault movements

tectonics and sedimentation in the gulf of corinth and the zakynthos and kefallinia channels western greece abstract single channel seismic reflection profiling data are presented from the gulf of corinth and from the continental margin outside the gulf of patras different tectonic styles are exhibited in the two regions the gulf of corinth is occupied by a complex asymmetrical graben structure with major faults trending nearly perpendicular to the local tectonic zones of the internal hellenides the gulf is interpreted to have formed during the quaternary in response to approximately north south extensional stress the deep floor of the gulf is underlain by a sequence of turbidites up to 1 km thick affected by normal growth faulting that extends up to the sea floor the sea areas inside the ionian islands of zakynthos and kefallinia zakynthos and kefallinia channels occupy a broad structural depression that trends parallel to the local tectonic zones of the external hellenides and is situated on the continental side of the strophades continental margin rise the channels contain local nw se trending structural basins zakynthos and kefallinia basins whose geometry is controlled by reverse faults or thrusts with associated diapirism in triassic evaporites hydra bank is interpreted as a tilted fault block with a diapiric core and its faulted western margin can be traced into the zone of thrusting and diapirism in southeast kefallinia at the boundary between the ionian and pre apulian paxos zones of the external hellinides the zakynthos and kefallinia structural basins are filled with a variety of sediments including prodeltaic deposits in front of the modern delta complex of the acheloos river slumped masses and debris flow deposits and in the zakynthos basin occasional turbidites the boundary separating zones of extensional and compressional focal mechanisms for shallow earthquakes crosses the gulf of patras the inner part of which exhibits wnw ese trending graben tectonics apparently related to the gulf of corinth tectonic province onshore neotectonic studies around the gulf of patras are required in order to understand the nature and cause of the westward tectonic transition from wnw ese graben structures in the gulfs of corinth and patras to nw se oriented zones of subsidence with associated compressional tectonics and diapirism in the zakynthos and kefallinia channels

high sediment yields and cool wet winters test of last glacial paleoclimates in the northern mediterranean opposing models have been proposed for last glacial paleoclimates in the mediterranean area to discriminate between the alternative models we calculate variations in sediment yield within a high resolution stratigraphic framework developed for the alkyonides basin central greece latest quaternary highstand deposits are distinguised from lowstand lake corinth deposits on the basis of seismic reflection data and micropaleontological and palynological analyses of drop cores after depth conversion and calculation of solid sediment masses in successive time slices sediment discharge rates during the last glacial lowstand interval ca 70 12 ka are shown to have exceeded discharge rates during the preceeding interglacial highstand interval ca 128 70 ka by 60 implying enhanced seasonality during the glacial period with cool dry summer and wet winter conditions in the region sediment yield calculations can thus provide an empirical test of paleoclimate models and offer input to sequence stratigraphic models

use of grain size and magnetic fabric analyses to distinguish among depositional environments the combined use of grain size and magnetic fabric analyses provides the ability to discriminate among depositional environments in deep sea terrigenous sediments we analyzed samples from three different depositional settings turbidites pelagic or hemipelagic interlayers and sediment drifts results indicate that sediment samples from these different environments can be distinguished from each other on the basis of their median grain size sorting as well as the intensity and shape of magnetic fabric as determined from an examination of the anisotropy of magnetic susceptibility we use these discriminators to interpret downcore samples from the bermuda rise sediment drift we find that the finer grains of the bermuda rise relative to the blake outer ridge do not result from lower depositional energy current speed and so may reflect a difference in the nature of sediment being delivered to the site i e distance from source between the two locations

the north anatolian fault a new look dedicated to the memory of three pioneers ihsan ketin sirri erinc and melih tokay and a recent student aykut barka who burnt himself out in pursuit of the mysteries of the north anatolian fault abstract the north anatolian fault naf is a 1200 km long dextral strike slip fault zone that formed by progressive strain localization in a generally westerly widening right lateral keirogen in northern turkey mostly along an interface juxtaposing subduction accretion material to its south and older and stiffer continental basements to its north the naf formed approximately 13 to 11 ma ago in the east and propagated westward it reached the sea of marmara no earlier than 200 ka ago although shear related deformation in a broad zone there had already commenced in the late miocene the fault zone has a very distinct morphological expression and is seismically active since the seventeenth century it has shown cyclical seismic behavior with century long cycles beginning in the east and progressing westwa

6600 years of earthquake record in the julian alps lake bohinj slovenia sequences of lake sediments often form long and continuous records that may be sensitive recorders of seismic shaking a multi proxy analysis of lake bohinj sediments associated with a wellconstrained chronology was conducted to reconstruct holocene seismic activity in the julian alps slovenia a seismic reflection survey and sedimentological analyses identified 29 homogenite type deposits related to mass wasting deposits the most recent homogenites can be linked to historical regional earthquakes i e 1348 ad 1511 ad and 1690 ad with strong epicentral intensity greater than damaging viii on the medvedev sponheuer karnik scale the correlation between the historic earthquake dataset and the homogenites identified in a core isolated from local stream inputs allows interpretation of all similar deposits as earthquake related this work extends the earthquake chronicle of the last 6600 years in this area with a total of 29 events recorded the early holocene sedimentary record is disturbed by a seismic event 6617 94 yr cal bp that reworked previously deposited sediment and led to a thick sediment deposit identified in the seismic survey the period between 3500 to 2000 yr cal bp is characterized by a major destabilization in the watershed by human activities that led to increases in erosion and sedimentation rates this change increased the lake s sensitivity to recording an earthquake earthquake sensitivity threshold index with the occurrence of 72 turbidite type deposits over this period the high turbidite frequency identified could be the consequence of this change in lake earthquake sensitivity and thus these turbidites could be triggered by earthquake shaking as other origins are discarded this study illustrates why it is not acceptable to propose a return period for seismic activity recorded in lake sediment if the sedimentation rate varies significantly

paleoseismicity of the cascadia subduction zone evidence from turbidites off the oregon washington margin cores from cascadia deep sea channel contain sequences of turbidites that can be correlated and dated by the first occurrence of volcanic glass from the mount mazama eruption 6845 50 radiocarbon yrbp turbidity currents from the tributaries appear to have occurred synchronously to form single deposits in the main channel there being only 13 turbidite deposits in the lower main channel since the mazama eruption instead of the twice as many expected if the tributaries had behaved independently in addition to the cascadia channel 13 post mazama turbidites have been deposited in the astoria canyon and at two sites off cape blanco sample locations that span 580 km of the oregon washington margin pelagic intervals deposited between the turbidites suggest that in each place the turbidity currents occurred fairly regularly every 590 170 years on average the best explanation of the spatial and temporal extent of the data is that the turbidity currents were triggered by 13 great earthquakes on the cascadia subduction zone the variability of turbidite timing is similar to that for great earthquake cycles the thickness of the topmost pelagic layer suggests the last event was 300 60 years ago from three places along the margin but this number may be a biased underestimate it is however consistent with the youngest sudden subsidence event on the washington coast the turbidite data demonstrate that the near term hazard of a great earthquake on the cascadia subduction zone is of the order of 2 10 in the next 50 years

the magnetic signature of rapidly deposited detrital layers from the deep labrador sea relationship to north atlantic heinrich layers rock magnetic parameters from deep labrador sea piston core p 094 are useful for recognizing rapidly deposited detrital layers some of which correlate with north atlantic heinrich layers variations in magnetic properties and lithology distinguish two classes of rapidly deposited detrital layers during the last ice age 1 seven detrital carbonate dc layers have high carbonate content and mean magnetite grain diameters about 4 times greater than the background sediments 2 six low detrital carbonate ldc layers have very similar magnetic properties to dc layers but low carbonate content similar to the background sediments the magnetite associated with dc and ldc layers is well sorted and relatively uniform within and between layers ice rafted detritus ird recognized by increased percentage of the 125 micron grain size fraction and by high magnetic susceptibility is associated with most dc and ldc layers but is not the dominant detrital constituent the correspondence of dc and ldc layers with increased grain size of well sorted magnetite but not with coarse fraction content precludes ice rafting as the primary depositional mechanism dc and ldc layers may have been deposited from suspended sediment derived from turbidite activity in the nearby northwest atlantic mid ocean channel namoc this interpretation is supported by a piston core p 013 from a greenland rise site largely but not completely outside the influence of the namoc the association of dc layers with ird and the apparent age correlation of dc layers to north atlantic heinrich layers suggest that the ice advances which produced the ird in p 094 and in correlative north atlantic heinrich layers also triggered turbiditic flows down the namoc several dc and ldc layers however do not correlate with recognized heinrich layers but appear to be coeval with recently discovered high frequency ird rich layers in the north atlantic

prehistoric earthquake deformations near masada dead sea graben earthquake inducedfluidizations and suspensions of lake sediments associated with syndepositionalfaults formapaleoseismicrecordinthedeadseagraben theassociation offluidized beds with surface faulting supports the recognition of mixed layers as reliable earthquake indicators and provides a tool for the study of very long term 70 kar seismicity along the dead sea transform the faults compose a fault zone that offsets laminated sediments of the late pleistocene lake lisan they exhibit displacements of as much as 2 m layers of massive mixtures of laminated fragments are interpreted as disturbed beds each formed by an earthquake the undisturbed laminated layers between these mixed layers represent the interseismic interval a typical vertical slip of about 0 5 m per event is separated by several hundred years of quiescence the fault zone lies within the dead sea graben 2 km east of masada where archaeology and historical accounts indicate repeated strong earthquake damage the distribution of strikes in the fault zone resembles that of the faults exposed in and around the graben including the seismogenic ones the excellent exposures over hundreds of metres allow an unprecedented temporal and spatial resolution of slip events on faults

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

late quaternary lacustrine paleo seismic archives in north western alps examples of earthquake origin assessment of sedimentary disturbances abstract the late quaternary sedimentary fills of several lakes of the north western alps are revealed to be possible paleo seismological archives in a moderately active seismo tectonic region the strongest historically reported events can be correlated with specific layers whose textures result from different processes i mass failures of sub aqueous slope deposits especially delta foresets evolving into hyperpycnal currents influenced by seiche effects and or multiple reflections on lake basin slopes ii in situ liquefaction and flowage and iii micro fracturing based on identification of the sedimentary signature of a well documented historical earthquake the paleoseismic interpretation can be extrapolated back to 16 000 yrs bp with a reconstruction of a time series and textural identification of slope failure related turbidites the most frequent earthquake signature the obtained time series are compatible with historical seismicity in terms of recurrence interval

paleoseismicity along the southern kuril trench deduced from submarine fan turbidites abstract large m 8 damaging interplate earthquakes occur frequently in the eastern hokkaido region northern japan where the pacific plate is subducting rapidly beneath the okhotsk north american plate at approximately 8 cm yr 1 with the aim of estimating the long term recurrence intervals of earthquakes in this region seven sediment cores were obtained from a submarine fan located on the forearc slope along the southern kuril trench japan the cores contain a number of turbidites some of which can be correlated among the cores on the basis of the analysis of lithology chronology and the composition of sand grains foraminiferal assemblages and the composition of sand grains indicate that the upper middle slope 1000 m water depth is the source of the turbidites the deep sea origin of the turbidites is consistent with the hypothesis that they were derived from slope failures initiated by strong shaking associated with earthquake events the recurrence intervals of turbidite deposition are 113 439 yr for events that occurred over the past 7 kyr the short intervals are recorded in the cores obtained from levees on the middle fan although many large earthquakes 150 cm s 2 of peak ground acceleration at the inferred slump sources occurred during the 19th and 20th centuries the pilot core from the upper fan contains only three turbidites located stratigraphically above layers of 17th century volcanic ash the results of 210pbex and 137cs dating combined with simulations of the ground accelerations of historical earthquakes enable correlation of the three turbidites with known historical earthquakes the 1952 tokachi oki and the 1961 and 1973 nemuro oki earthquakes the turbidites within the sampled cores potentially record about half of the large earthquakes known to have occurred over the interval covered by the cores the fact that any single core records only a portion of the known seismic events suggests that the recurrence interval of earthquakes in this region is less than 113 yr during holocene

alternating marine and lacustrine sedimentation during late quaternary in the gulf of corinth rift basin central greece abstract the gulf of corinth in central greece has a maximum depth of about 900 m and is separated from the open sea by the rion strait with a sill depth of 62 m marked by an extensive submarine terrace during eustatic sea level lowstands the gulf of corinth was a lake under lacustrine conditions stratified sediments accumulated in the deep water basins and turbid underflows from rivers eroded the basin slopes as the sea level rose marine waters flooded the gulf and deltas prograded across the shelves in shallow water areas two key reflectors termed z and x are terrace surfaces commonly erosional which mark the base of the overlying deltaic sequences in deep water basins z and x mark the top of the acoustically stratified sediments interpreted as lacustrine turbidites reflectors y and w mark the base of these stratified intervals and overlie acoustically transparent sections similar to the holocene section the last lacustrine conditions in the gulf z to y were during isotopic stage 2 and terminated about 12 000 yr ago age estimates based on sedimentation rates suggest that the x to w interval corresponds to the stage 4 lowstand of sea level in the western gulf of corinth shoreline transgressive surfaces corresponding to minor transgressions in stage 5 and to major transgression at the end of stage 6 are recognised this seismic stratigraphy permits a detailed interpretation of the history of the gulf of corinth in the past hundred thousand years it also provides a general model for sedimentation in rift basins in which marine and lacustrine sediments alternate

acquisition of detrital magnetization in four turbidites turbiditic events are mostly avoided in paleomagnetic studies and therefore their remanence and magnetic properties are poorly described turbidites are exempt of bioturbation and potentially provide pertinent information about depositional remanence we studied four quaternary turbidites of different origins in marine sediment cores upward fining of both magnetic and sedimentary fractions indicates that coarser grains reached the bottom first we observe a progressive shallowing of the magnetic inclinations between the upper and bottom layers of the turbidites that increases with the size of the events and obeys a simple linear scaling law measurements of magnetic anisotropy suggest that hydrodynamic conditions prevailing during deposition seem to be dominant for the alignment of the magnetic grains we suggest that small spherical grains are randomly oriented with zero resultant magnetization in presence of strong turbulent conditions while the alignment of elongated grains is constrained by the competition between gravity and magnetic forces a possible scenario is that under turbulent conditions they tend to rest at the bottom with their long axes parallel to the sediment surface and therefore with shallow inclinations whereas weakly turbulent conditions like during the smallest 26 cm thick event do not disturb the magnetic alignment and therefore do not generate inclination shallowing this article is protected by copyright all rights reserved

sedimentary characteristics and depositional models of two types of homogenites in an eocene continental lake basin shulu sag eastern china abstract homogenites are homogeneous and structureless fine grained rocks they have been studied extensively in marine settings and are typically interpreted as being related to catastrophic events such as earthquakes however studies on lacustrine homogenite like rocks are limited new core data from the shulu sag in china reveal that thick massive calcilutites exist in the lower shahejie 3 formation which formed during the middle eocene rifting stage based on petrographic geochemical and mineralogical data these massive calcilutites are interpreted as homogenites and grouped into two types type a homogenite is composed of intrabasinal materials characterized by high calcite total organic carbon toc content and 13c value type a homogenite has two facies successions the first of which is characterized by homogeneous appearance capped by an erosional interface and the second is characterized by repeated massive laminated calcilutite successions type b homogenite contains abundant allochthonous materials displaying relatively high dolomite content and low calcite toc and 13c content type b homogenite represents the topmost finer portion of a graded megabed which includes from base to top grain supported carbonate conglomerates slumped deformed portions and debrites the whole unit can be considered as a megaturbidite earthquakes are the most reasonable triggers of homogenite formation in the shulu sag type a homogenites are thought to be derived by fluidification resuspension and decantation of lacustrine fines due to shock waves generated by an earthquake type b homogenites might be deposits of distal turbidity currents and turbid clouds transformed from other gravity flows the results of this study provide a better understanding of the formation of homogenites caused by earthquakes in a confined lacustrine basin

generation and maintenance of abnormal fluid pressures beneath a ramping thrust sheet isotropic permeability experiments abstract we have investigated the mechanisms responsible for the evolution of excess pore pressures within and beneath a ramping thrust sheet i e fluid flow porosity compression and thermal expansion of water and the sensitivity of pore pressure to a variety of physical parameters e g permeability thrust sheet velocity heat flux coupled pore pressure and temperature equations were solved numerically in two dimensions using a generalized hydrostratigraphy of north american thrust belts because of the lack of either symmetry or a steady state in this problem both deposition and thrust loading stages were simulated the dominant mechanisms controlling pore pressure evolution were fluid flow and compression of pore space by vertical loading thermal expansion of the fluids was found to be insignificant in generating excess pore pressures at common thrust loading rates the results indicate that it is possible to generate high pore pressure to lithostatic pressure ratios within thrust sheets by depositional loading prior to thrusting high values of are generated and maintained during thrust loading for reasonable assumptions about the conditions thought to have existed in thrust belts values of were not constant throughout the model the highest values tended to concentrate near the surface of the model and within and below the toe of the thrust sheet the magnitude and distribution of excess pore pressures and values were found to be especially sensitive to variations in permeability excess pore pressure generation by compression exceeded pore pressure dissipation by fluid flow for permeabilities less than approximately 10 16 m 2 permeabilities greater than approximately 10 16 m 2 produced hydrostatic pore pressure gradients the models demonstrate that permeability inhomogeneity due to lithologic variations may exert a strong control on the magnitude and spatial distribution of excess pore pressures within thrust sheets in addition these models indicate that it is unlikely that fluid pressure is high everywhere in a moving thrust sheet

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

1822 earthquake triggered homogenite in lake le bourget nw alps high resolution textural signatures of an earthquake induced historical homogenite layer are presented as well as its 3d distribution this homogeneous deposit is correlated with the ad 1822 event vii viii msk intensity the main historical earthquake of the french outer alps using 210pb dating and historical chronicles during this earthquake a violent lake water oscillation was reported seiche effect in the present study we discuss the influence of lake water oscillations during earthquake induced subaqueous slide through a pluridisciplinary analysis of subbottom sediments including high resolution seismic sidescan sonar and short gravity coring

sedimentary impacts of recent moderate earthquakes from the shelves to the basin floor in the western gulf of corinth abstract in seismically active areas long term records of large earthquakes are indispensable to constrain reccurence patterns of large earthquakes in the western corinth rift one of the most active areas in europe in terms of seismicity data about ancient earthquakes are still insufficient despite historical records covering the last two millenia and several studies in onshore paleoseimology in this paper we test the use of offshore sediments from the gulf of corinth to identify sediment failures and tsunamis that have been triggered by historical earthquakes two shelves 40 100 m deep one sub basin 180 m and the basin floor 330 m have been sampled by short gravity cores the cores were analyzed in order to identify and characterize event deposits the age control has been provided by 137cs and 210pb activity measurements showing that the cores represent 2 to 4 centuries of sedimentation in each site sandy event deposits are interbeded in the muddy hemipelagic sedimentation the age of event deposits has been compared to the record of historical earthquakes using new and published macroseismic data this comparison shows temporal coincidence of some event deposits and documented earthquakes with a macroseismic intensity vii in the area e g in 1861 ce 1888 ce and 1909 ce in nearshore shallow water settings the record of event deposits does not exactly fit with the historical record of large earthquakes because too few event deposits are present this may be due to the absence of sediment failures or to a lower preservation of the deposits in such settings in the deepest site in the basin floor the correspondence is better a sandy turbidite probably corresponds to each large earthquake since 1850 ce except one aseismic sediment density flow that occurred at the end of the 20th century surprisingly the ms 6 2 june 15 1995 aigion earthquake is only possibly recorded in one nearshore site on the aigion shelf in the form of a tsunami back wash flow deposit this study showed that moderate earthquakes m 5 8 6 5 can significantly impact marine sediments regarding the evaluation of seismic hazard in the area the basin floor is proposed as a promising site for long term paleoseismology in the gulf of corinth while shallower settings need to be considered more carefully

disentangling late quaternary climatic and seismo tectonic controls on lake mucubaji sedimentation merida andes venezuela abstract lake mucubaji is a moraine dammed lake crossed by the bocono fault in the merida andes venezuela four long piston cores up to 8 m long and 24 short gravity cores 0 6 to 0 8 m long were collected to study the sedimentary fill of the lake lithostratigraphy magnetic susceptibility organic and inorganic contents and 14 c ages permit lateral correlations between the cores and with an emerged part of the former larger lacustrine basin fill the cored succession spans the last 16 000 years several abrupt changes in sediment texture and composition are ascribed to depth and surface modifications together with soft sediment disturbances they are related to the seismo tectonic activity of the bocon fault shock induced phenomena slumps seiche effects liquefaction and co seismic scarps four major earthquakes indicate a mean minimum recurrence interval of 1200 years which is consistent with trench data obtained from a neighbouring active trace of the bocono fault system despite the seismo tectonic imprint a general post lgm climatic trend can be traced and correlated with northern hemisphere global evolution in particular for the last 13 000 years

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

inclination anomalies from indian ocean sediments and the possibility of a standing nondipole field we report magnetic inclinations measured in deep sea sediments of the equatorial indian ocean which record the behavior of a nondipole component of the time averaged geomagnetic field during the plio pleistocene 0 5 ma the magnitude of the nondipole effect recorded in these sediments appears to depend on polarity state with inclinations showing departures from geocentric axial dipole directions which are small 2 o during normal polarity and larger 5 o during reverse polarity times the overall nondipole effect observed here is consistent with prior spherical harmonic estimates of the paleomagnetic field the polarity bias found agrees in both sense and magnitude with earlier reports of polarity asymmetry in the low degree zonal harmonic fields the presence of this asymmetry supports previous suggestions of the existence of a standing component of the nondipole field which does not invert during reversals of the main field we explore whether the standing field so indicated may have influenced paleomagnetic directions recorded during polarity transitions at other equatorial sites

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

an inverse solution for the depth and frequency dependent sediment attenuation of low frequency 20 320 hz compressional waves the mechanisms that control low frequency acoustic propagation and that are unique to the shallow water environment are resident in the seabed a method of determining the sediment attenuation of low frequency compressional waves as a function of frequency and sediment depth is examined the method utilizes the backus gilbert geophysical inverse theory and the emphasis is placed on assessing the resolution and error associated with the inferred structure and the experimental geometry rather than merely obtaining a solution that fits the simulated data a laterally homogeneous geoacoustic test model is used to generate artificial data for input to the inverse procedures the results provide insights regarding resolution and error for generically similar sediments and experimental geometries

effects of frictional heating on the thermal hydrologic and mechanical response of a fault the mechanical response of a fault zone during an earthquake may be controlled by the diffusion of excess heat and fluid pressures generated by frictional heating in this study we formulate a fault model which incorporates the effects of frictional heating on the thermal hydrologic and mechanical response of a small patch of the failure surface this model is used to examine the parameters that control the fault response and to determine their critical range of values where thermal pressurization is significant the problem has two time scales a characteristic slip duration and a characteristic time for thermal pressurization the slip duration is set by the fault geometry the characteristic time for thermal pressurization is set by the slip rate the friction coefficient and the thermal and hydraulic characteristics of the medium the response of the fault depends on the relative magnitude of these two times results suggest that the fault width and hydraulic characteristics of the fault zone and adjacent medium are the primary parameters controlling the mechanical response for earthquakes occurring across zones of low porous medium compressibility 10 9 pa 1 and permeability 10 18 m2 the characteristic time for thermal pressurization is small in this case frictional heating can cause fluid pressures to approach lithostatic values the shear strength to approach zero and the temperature rise to stabilize at a maximum value dependent on the pore dilatational and transport properties of the porous medium whether the patch acts as a barrier to slip or exhibits substantial strain weakening is dependent on the shear strain across the fault moderate slip events where shear strains exceed two cause substantial strain weakening and consequently large stress drops accelerations and displacements thus it is possible for the patch to act as a barrier for small earthquakes but not for large ones both the dynamic stress drop and total displacement decrease for zones with larger compressibility permeability or width if the compressibility or permeability exceeds 10 8 pa 1 or 10 14 m2 or the shear strain is less than one then the effects of frictional heating may be negligible and the fault will exhibit no strain weakening characteristics consequently the patch acts as barrier that halts or resists further fault motion extrapolation of these results suggests that spatial variations in fault width and hydraulic characteristics will cause a heterogeneous stress drop and fault slip over the failure surface explaining many of the features of active faulting e g barriers nonuniform slip rupture stoppage random ground accelerations strong motions and frequency magnitude relations

distinguishing between rooted and rootless detachments a case study from the mormon mountains of southeastern nevada abstract rooted detachment faults and detachments beneath rootless slide blocks exhibit many similar structural characteristics however while rooted detachments are thought to penetrate into the midcrust and to accommodate significant crustal extension rootless detachments break to the surface downdip and are not directly involved in such extension distinguishing between these two mechanically different kinds of structure is central to the assessment of extension magnitude here we examine deformation along the mormon peak detachment a feature that has been cited as an example of both a rooted and a rootless structure located in the mormon mountains of southeastern nevada this detachment has been interpreted as one of three low angle normal faults of regional scale that together are thought to have accommodated more than 50 km of basin and range extension for the most part however the mormon peak detachment is expressed as a series of isolated exposures where paleozoic rocks are in brittle fault

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

the terraces of corinth gerrce a detailed record of eustatic sea level variations during the last 500 000 years abstract between corinth and xylokastro 20 marine terraces reflect the interaction of the northern peloponnese uplift and the global eustatic sea level fluctuations during the last 500 000 years correlation of the terraces with oxygen isotope records in deep sea cores allowed accurate dating of these fossilized transgressive shorelines curves of altitude versus age have been plotted they show a regular decrease of the uplift rate and a frequent return of the sea level very close to the present day one not only during the interglacial periods 5 7 9 11 13 but also during glacial periods 3 1 3 3 6 8 the alternative would be to suppose very complicated and highly improbable vertical movements of the substratum to explain the regularity of the curves the rhythm of these high sea levels is around 20 30 ka since at least 330 000 years ago

gps constraints on africa nubia and arabia plate motions summary we use continuously recording gps cgps and survey mode gps sgps observations to determine euler vectors for relative motion of the african nubian arabian and eurasian plates we present a well constrained eurasia nubia euler vector derived from 23 igs sites in europe and four cgps and three sgps sites on the nubian plate 0 95 4 8 n 21 8 4 3 e 0 06 0 005 myr 1 we see no significant 1m m yr 1 internal deformation of the nubian plate the gps nubian eurasian euler vector differs significantly from nuvel 1a 21 0 4 2 n 20 6 0 6 e 0 12 0 015 myr 1 implying more westward motion of africa relative to eurasia and slower convergence in the eastern mediterranean the arabia eurasia and arabia nubia gps euler vectors are less well determined based on only one cgps and three sgps sites on the arabian plate the preliminary arabia eurasia and arabia nubia euler vectors are 27 4 1 0 n 18 4 2 5 e 0 40 0 04 myr 1 and 30 5 1 0 n 25 7 2 3 e 0 37 0 04 myr 1 respectively the gps arabia nubia euler vector differs significantly from nuvel 1a 24 1 1 7 n 24 0 3 5 e 0 40 0 05 myr 1 but is statistically consistent at the 95 per cent confidence level with the revised euler vector reported by chu gordon based on a re evaluation of magnetic anomalies in the red sea 31 5 1 2 n 23 0 2 7 e 0 40 0 05 myr 1 the motion implied in the gulf of aqaba and on the dead sea fault dsf by the new gps nubia arabia euler vector i e ignoring possible sinai block motion and possible internal plate deformation grades from pure left lateral strike slip in the gulf and on the southern dsf with increasing compression on the central and northern dsf with relative motion increasing from 5 6 to 7 5 mm yr 1 1m m yr 1 from south to north along the northern dsf i e north of the lebanon restraining bend motion is partitioned between 6 1m m yr 1 left lateral motion parallel to the fault trace and 4 1m m yr 1 faultnormal compression relative motions on other plate boundaries including the anatolian and aegean microplates derived from the gps euler vectors agree qualitatively with the sense of motion indicated by focal mechanisms for large crustal earthquakes m 6 where data are available on fault slip rates on plate bounding faults north anatolian fault east anatolian fault dead sea fault red sea rift they are generally lower than but not significantly different from the full plate motion estimates suggesting that the majority of relative plate motion is accommodated on these structures

first evidence of a mid holocene earthquake triggered megaturbidite south of the chile triple junction abstract megaturbidites have been the focus of many paleoseismic and paleoenvironmental studies because they can provide evidence for catastrophic and or hazardous events with potentially major environmental implications during a recent research cruise in baker fjord chile 47 54 s 74 30 w a megaturbidite was described between the northern and southern patagonian icefields here we aim to determine the depositional processes of the megaturbidite and identify its origin based on the turbidite s location a possible origin was the early holocene drainage of paleo lake general carrera which was recently proposed in the literature as having produced a glacial lake outburst flood glof that drained through baker fjord due to the fjord s location in a subduction zone and close to the chile triple junction however seismic activity must also be considered as a potential triggering mechanism to achieve our goals we undertook a multi proxy analysis of sediment core md07 3121 including sedimentology grain size loss on ignition foraminifera counts magnetic properties bulk organic geochemistry and radiocarbon dating and we analysed bathymetric maps and sub bottom profiles our grain size results display a diagnostic fining upward trend and show evidence of seiching in the 733 cm thick megaturbidite the age of the event 5513 5211 cal yr bp contradicts the hypothesis of an early holocene glof origin bulk organic geochemical results indicate that the sediments that compose the turbidite are clearly of marine origin which further goes against a glof origin in addition the megaturbidite is underlain by a 1136 cm thick mass transport deposit mtd also composed of marine sediments according to the sub bottom profiles the mtd and the megaturbidite originate from the reworking of thick packages of sediment previously deposited on nearby sills and on the fjord s flanks furthermore similar coeval deposits are found in an adjacent sub basin we therefore interpret these deposits to be triggered by an earthquake during the late mid holocene while megathrust and intraslab earthquakes are possible in the region we argue that a crustal earthquake is the most likely seismic trigger in the study area this study reveals the first earthquake triggered megaturbidite south of the chile triple junction

sedimentary records of past earthquakes in boraboy lake during the last ca 600 years north anatolian fault turkey abstract multiproxy sedimentological analyses along 4 9 m long sequence of boraboy lake which is located on the central eastern part of the north anatolian fault naf reveal the sedimentary traces of past large earthquakes in the region the lake has a relatively large catchment area 10 km2 compared to its size 0 12 km2 which renders sedimentation sensitive to heavy rain storm events accordingly the background sedimentation which is composed of faintly laminated reddish yellowish brown clayey silt is frequently interrupted by organic rich intercalations probably due to heavy rain storm events transporting terrestrial plant remains from the densely vegetated catchment in addition to frequent organic rich intercalations the background sedimentation is interrupted by four mass wasting deposits mwd of which thickness range is between 15 and 50 cm high resolution itrax xrf data confirms higher homogeneity along the mwds e1 e4 compared to the background sedimentation based on 137cs and 210pbxs dating and radiocarbon chronology three mwds detected in boraboy sequence e2 e3 and e4 temporally correlate with large historical earthquakes along the naf the 1943 tosya ms 7 6 and or 1942 niksar erbaa ms 7 1 the 1776 amasya merzifon and the 1668 north anatolian ms 7 9 earthquakes the youngest mwd in the sequence e1 which is dated to early 2000s does not correlate with any strong earthquake in the region this mwd was probably a single mass wasting event due to routine overloading and oversteepening on the delta front formed by the main inlet of the lake in subaqueous paleoseismology coevality of multi location mass wasting events is used as a criterion to assign a seismic triggering mechanism and to rule out mass wasting events due to routine overloading oversteepening of subaqueous slopes within this context boraboy sequence provides a valuable example to discuss sedimentological imprints of single vs multi source mwds

magnitude distance relations for earthquake induced landslides in greece a data set of 47 earthquake induced landslides occurring in greece from ad 1650 to 1995 has been compiled and the landslide distribution has been examined the spatial distribution indicates landslides occurrence almost everywhere in greece with the exception of the north greek mainland which is likely due to the low occurrence frequency of large earthquakes the earthquake magnitude m s ranges between 5 3 and 7 9 while the main bulk of events falls within the range 7 5 m s 5 3 with peaks at m s 6 4 and 6 7 the upper bound of the maximum epicentral distance r e from a reported landslide has been approximated by the line log r e 2 98 0 75m s for m s 5 3 which is compatible with curves proposed world wide and constitutes a realistic solution at least for hazard assessment purposes we discuss the importance of the results for assessing hazards from earthquake induced landslides and for calculating focal parameters of historical earthquakes 2000 elsevier science b v all rights reserved

rock magnetism of late neogene and pleistocene deep sea sediments relationship to sediment source diagenetic processes and sediment lithology we use bivariate scatter plots to illustrate variations in selected rock magnetic properties low field susceptibility anhysteretic and isothermal remanence of late neogene and pleistocene deep sea sediments from 16 sites in the arctic ocean north atlantic equatorial atlantic and north pacific ocean and the arabian sea our intention is to examine the ability of the rock magnetic properties to differentiate the sediments according to factors such as lithology geographical area and the dominant mode of terrigenous sedimentation which at these sites is via ice rafting via bottom currents or via eolian processes overall correlations between sediment magnetic properties and gross lithology is poor and factors such as the source and transport path of terrigenous sediment and detrital magnetic minerals together with the action of reductive diagenetic processes are the major controls on the magnetic properties on the bivariate scatter plots sites with major ice rafted contributions tend to have high sedimentary ferrimagnetic mineral concentrations relatively coarse ferrimagnetic grain sizes and scattered sample point distributions in contrast sites where we infer significant bottom current supply of terrigenous material have tightly grouped sample point distributions carbonate sediments in which the terrigenous component is supplied by eolian processes tend to have a broad range of magnetic mineral concentration caused by glacial interglacial fluctuations in carbonate accumulation and eolian activity sediments containing significant volcanogenic material have high concentrations of relatively coarse grained ferrimagnetic material reductive diagenesis is a significant determinant of sediment magnetic properties in high productivity areas and has the effect of preferentially removing the fine grained ferrimagnetic fraction causing a coarsening of the ferrimagnetic grain size distribution and a rise in the antiferromagnetic ferrimagnetic ratio

timing of exhumation wheeler pass thrust sheet southern nevada and california late jurassic to middle cretaceous evolution of the southern sevier fold and thrust belt zircon u th he zhe thermochronologic data for 46 samples from the wheeler pass thrust sheet which carries thick passive margin strata and is discontinuously exposed across the southern part of the sevier fold and thrust belt record late jurassic cooling related to exhumation during early thrust slip and local middle cretaceous cooling related to footwall basement imbrication within the frontal part of the wheeler pass sheet exposed in the northwest spring mountains zhe ages decrease from ca 160 to 140 ma over a paleodepth interval of 6 to 9 km in devonian to lower cambrian strata interpreted to record exhumation and enhanced cooling above a frontal ramp followed by slow cooling a similar pattern of zhe ages occurs over a more limited paleodepth range exposed within the resting spring range to the south in the nopah range zhe ages of ca 140 ma in lower cambrian strata record early cooling followed by slow cooling until ca 100 ma zhe ages in underlying paleoproterozoic basement rocks decrease from ca 100 to 85 ma over a paleodepth interval of 9 to 12 km interpreted to record uplift exhumation and cooling during footwall basement imbrication as slip was transferred eastward onto the keystone thrust system late jurassic slip on the wheeler pass thrust overlapped with deformation along the nw trending east sierran thrust system early hinterland crustal thickening and growth of the sierra magmatic arc and may have been correlative with early deformation in the central nevada thrust belt slip on the wheeler pass thrust preceded major slip on other thrust sheets that carried thick passive margin strata in more northern parts of the sevier belt probably reflecting the influence of different initial widths and tapers of the passive margin sedimentary wedge

hot on the trail coseismic heating on a localized structure along the muddy mountain fault nevada abstract recent advances in the use of thermal proxies to identify past earthquake slip in exhumed faults have created an extraordinary opportunity to map the geometry of past ruptures in unprecedented detail this approach can reveal along strike differences in the structure and speed of earthquake slip here we present organic thermal maturity data collected along the muddy mountain thrust in nevada to investigate where it was within the fault that earthquake slip occurred and whether this is consistent along strike we observe large changes in thermal maturity which represent temperature rise variations along the fault modeling of thermal maturity measurements yield peak temperatures of 760 1090 c where the principal slip zone psz is narrowest 0 8 mm nearby where the psz is thicker 1 5 mm these temperatures did not exceed 500 c based upon estimates of temperature rise within a submillimeter psz mean frictional work during earthquake slip was 6 3 7 1 mjm 2 these results show that thickness of the active slipping zone can vary at small spatial scales and development of a continuously narrow

late quaternary co seismic sedimentation in the sea of marmara s deep basins the deep northern part of the sea of marmara northwestern turkey is composed of several aligned actively subsiding basins which are the direct structural and morphological expression of the north anatolian fault s northern branch the last 20 kyr of their sedimentary fill lacustrine before 12 kyr bp have been investigated through giant piston coring onboard r v marion dufresne marmacore cruise 2001 and chirp subbottom profiler onboard r v atalante during marmarascarps cruise 2002 especially during the lacustrine stage the infilling of the deep basins tekirda central kumburgaz and cinarcic basins up to 1250 m depth was dominated by turbidites with coarse mixed siliciclastic and bioclastic basal part intercalated in hemipelagic type finegrained calcareous and slightly siliceous clays often especially in the thickest ones the turbidites show strong segregation and a sharp boundary between coarse part and suspendedload part in the central basin 8 m of a unique sedimentary event include a 5 to 8m thick homogenite well imaged on seismic profiles the latter is interpreted as related to a major possibly triggered tsunami effect as described in the eastern mediterranean by kastens and cita 1981 in the marine holocene upper part of the sedimentary fill repeated to and from structures affecting silt or fine sand are evidencing seiche like effects and thus earthquake triggering detailed correlations between two deep coring sites 1250 and 1200 m indicate more than 100 overthickening in the deepest one this implies specific processes of distribution of terrigenous input by dense hyperpycnal currents high kinetic energy seiche effect complex reflections on steep slopes the peculiar sedimentary infilling of the sea of marmara s central basin and by extrapolation of the whole set is tentatively interpreted as a direct consequence of the strong seismic activity the imprint of the latter is more obvious prior to the base of the holocene as environmental conditions favoured marginal accumulation especially on the southern shelf of large amounts of erosion products available for mass wasting

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

influence of bottom currents on the sedimentary processes at the western tip of the gulf of corinth greece abstract we investigated the sedimentary processes that were active during the holocene in the gulf of corinth using high resolution seismic reflection profiles and gravity cores seismic reflection data clearly show the presence of shallow water sediment drifts at the western end of the gulf close to the rion sill that links the gulf to the ionian sea short cores indicate that drifts are composed of homogenous bioturbated mud in their upper part the drift deposits flank a wide central area where the seafloor is eroded and where pre holocene deposits locally outcrop the seafloor morphology in this area is marked by furrows oriented in different directions and by a depression attributed to the action of bottom currents the magnetic fabric of sediment samples from the drift shelves sub basins and from the basin floor shows a significant anisotropy and a similar orientation of k max axes along core the largest anisotropy p 1 043 0 007 is observed in the drift and is interpreted as resulting from the action of bottom currents the similar orientation of k max axes in the other cores collected from areas east of the drifts suggests that bottom currents also affect sediment deposition in the rest of the study area even if seismic profiles and core analyses demonstrate that gravitational processes such as submarine landslides and turbidity currents exert the main control on sediment transport and deposition average k max axes for four cores were reoriented using the declination of the characteristic remanent magnetization k max axes show variable orientations relatively to the slope of the seafloor between along slope and roughly parallel to the contour lines

increased marine sediment suspension and fluxes following an earthquake earthquakes are commonly cited as one possible triggering mechanism for turbidity flows dense sediment water plumes that can transport large volumes of sediment great distances down slope in both marine and lacustrine settings1 2 3 4 5 6 heezen and ewing1 were the first to make such a suggestion attributing breaks in a sea floor telephone cable in the north atlantic ocean to turbidity flows generated by the 1929 grand banks earthquake anumber of workers have consequently used sedimentary turbidite records to reconstruct the earthquake histories of various regions2 7 8 here we present direct observations of a seismically induced turbidity flow measurements of light scattering and sediment fluxes in the cariaco basin indicate that the earthquake that occurred along the coast of northern venezuela on 9 july 1997 resulted in considerable downslope displacement of sediments probably 105 tonnes into the deep part of the basin in such a seismically active region this mechanism of sediment transport may be responsible for a significant component of the long term sediment accumulation in the basin furthermore this process may result in the sequestration in deep sea sediments of large amounts of carbon initially deposited at shallow depths

the aigion neos erineos coastal normal fault system western corinth gulf rift greece geomorphological signature recent earthquake history and evolution 1 at the westernmost part of the corinth rift greece an area of rapid extension and active normal faulting geomorphological observations reveal the existence and geometry of an active nw se trending coastal fault system which includes the aigion fault we recognize a similar fault pattern on both the coastal range front to the nw of aigion town and the holocene fan deltas in front of it we interpret this as a result of recent migration of faulting to the hanging wall of the fault system differences in the geomorphic expression of the constituent faults provide hints on the possible evolution of the fault pattern during this recent migration a trench excavated across one of the identified coastal fault scarps on a holocene fan delta provides information on the seismic history of the fault system which includes at least four possibly six earthquakes in the past 4000 years a minimum estimate for the slip rate of the trenched fault is 1 9 2 7 mm yr the trench exposed sediments of an uplifted paleolagoon approximate age 2000 years b p inside which the last two earthquakes formed an underwater monoclinal scarp oscillating coastal vertical movements are suggested by the fact that the lagoonal deposits are also uplifted on the trenched fault hanging wall uplift by offshore faults and by the abrupt transition from fluvial to lagoonal deposits subsidence by more landward faults assuming that extensive coastal sediment failure has not taken place in the specific part of the fan delta within the time interval of interest these movements suggest that the proposed migration of activity from the range front faults to those on the fan deltas is probably still ongoing with activity on both sets of faults

derivation of direct on fault submarine paleoearthquake records from high resolution seismic reflection profiles wairau fault new zealand direct on fault submarine paleoearthquake records can be derived from high resolution seismic reflection profiles of active fault growth sequences coseismic vertical increments of displacement are best preserved in the architecture of the growth sequence when the long term rate of sedimentation exceeds the rate of fault vertical displacement postseismic stratigraphic intervals can be recognized on vertical displacement history curves from which estimates of the earthquake timing and vertical displacements can be made the strike slip wairau fault is a major seismic hazard in central new zealand and is partially submarine analysis of 10 high resolution seismic profiles spanning a 20 km section of the offshore fault trace reveals two types of postseismic growth sequences and a composite paleoearthquake record with up to eight surface rupturing earthquakes since 18 ka the recurrence intervals range from 0 9 to 3 8 ka mean is 2 2 ka while the coseismic vertical displacements range from 0 5 to 5 3 m mean is 2 5 m these data conform to the variable slip model of earthquake behavior the vertical coseismic displacement is not always predictable from the recurrence interval preceding the event the data indicate that the seismic moment release has not been constant between earthquakes or that the ratio of horizontal to vertical coseismic displacement at a given site has varied over multiple earthquake cycles the offshore data are consistent with onshore paleoearthquake records long term dextral slip rate of 2 mm yr compared to 3 5 mm yr 40 km in land and paleoearthquakes of mw 7 5 the last earthquake occurred on the fault 2 0 0 3 kyr ago indicating that significant elastic strain has now accrued

rupture lengths and temporal history of significant earthquakes on the offshore and north coast segments of the northern san andreas fault based on turbidite stratigraphy piston gravity and jumbo kasten cores were collected from channel and canyon systems draining the northern california continentalmargintoinvestigatetherecordofperiodicholoceneturbiditesforpossibleconnectiontolargemagnitudeearthquakeson the adjacent northern san andreas fault poorly known channel systems were mapped with multibeam sonar to define pathways and channel confluences cores sampled all major and many minor channel systems extending from cape mendocino to just north of monterey bay sampling both along and across channels was done and particular attention was paid to channel confluences as these areas afford opportunities to test for synchronous triggering of turbidity currents while at sea all cores were scanned using a geotek multisensor core logger mscl which collects high resolution photography p wave velocity gamma ray density and magnetic susceptibility data from the unsplit cores lithology was logged visually and cores were later imaged with x radiography we use 14 c ages relative dating tests at channel confluences and stratigraphic correlation using physical properties to determine

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