was the black sea catastrophically flooded in the early holocene abstract a catastrophic flooding of the black sea basin was proposed to have occurred during its reconnection to the ocean in the early holocene possible cultural consequences of the flood include the migration of neolithic farmers from around the black sea towards central europe as well as the creation of flood myths stratigraphic and paleo geomorphologic information from danube delta aided by radiocarbon ages on articulated mollusks constrain the level in the black sea before the marine reconnection to ca 30 m below the present sea level rather than 80 m or lower if the flood occurred at all the sea level increase and the flooded area during the reconnection were significantly smaller than previously proposed

plio quaternary paleostress regimes and relation to structural development in the kertch taman peninsulas ukraine and russia abstract in the kertch taman peninsulas located between the crimean and nw caucasus mountains deep troughs developed since oligocene time sediments were subsequently folded folding was associated with thrusting paleostress analyses allowed constraint of the tectonic evolution of the area an extensional event occurred before folding perhaps related to the trough development this event was followed by compression associated with plio quaternary folding stress tensors determined in older rocks in the crimean and nw caucasus belts are correlated with this regional plio quaternary compression in detail n s compression followed nw se compression this change in direction could be explained by a change of the direction of convergence of the black sea plate with the scythian plate the nw se compression induced ne sw folds in the southern part of the peninsulas the n s compression corresponds to e w folds of the northern part suggesting a northward propagation of the deformation front the structural evolution of the kertch taman region is controlled by 1 pre existing structures 2 a change in the direction of compression related to a change of the direction of convergence of the black sea with the scythian plate and 3 the northward propagation of the compressional front with the continuing indentation of the black sea block

the critical slip distance for seismic faulting experimentally based friction laws1 2 have been found to predict virtually the entire range of observed behaviour of natural faults3 4 these laws contain a critical slip distance l which plays a key role in determining the degree of fault instability the size of the zone of earthquake nucleation the frictional breakdown width and the proportion of pre and post seismic slip to co seismic slip in laboratory measurements l is found to be about 10 5m but modelling results show that it must be about 10 2m if natural earthquake behaviour is to be simulated the discovery that fault surfaces are fractal over the scale range 10 5 105 refs 5 6 even for faults with large net slip has confused the problem of scaling this parameter from laboratory experiments to natural faults because fractal surfaces have no characteristic length here i show that geometrically unmated fractal surfaces when in contact under a normal load develop a characteristic length in their contact because long wavelength apertures close under load whereas short wavelength apertures may remain open this critical distance may be identified with l and calculations based on fault topography data show that at seismogenic depths it will be in the range anticipated from the earthquake modelling studies

detailed observations of california foreshock sequences implications for the earthquake initiation process we find that foreshocks provide clear evidence for an extended nucleation process before some earthquakes in this study we examine in detail the evolution of six california foreshock sequences the 1986 mount lewis ml 5 5 the 1986 chalfant ml 6 4 the 1986 stone canyon ml 4 7 the 1990 upland ml 5 2 the 1992 joshua tree mw 6 1 and the 1992 landers mw 7 3 sequence typically uncertainties in hypocentral parameters are too large to establish the geometry of foreshock sequences and hence to understand their evolution however the similarity of location and focal mechanisms for the events in these sequences leads to similar foreshock waveforms that we cross correlate to obtain extremely accurate relative locations we use these results to identify small scale fault zone structures that could influence nucleation and to determine the stress evolution leading up to the mainshock in general these foreshock sequences are not compatible with a cascading failure nucleation model in which the foreshocks all occur on a single fault plane and trigger the mainshock by static stress transfer instead the foreshocks seem to concentrate near structural discontinuities in the fault and may themselves be a product of an aseismic nucleation process fault zone heterogeneity may also be important in controlling the number of foreshocks i e the stronger the heterogeneity the greater the number of foreshocks the size of the nucleation region as measured by the extent of the foreshock sequence appears to scale with mainshock moment in the same manner as determined independently by measurements of the seismic nucleation phase we also find evidence for slip localization as predicted by some models of earthquake nucleation

rapid flooding of the sunda shelf a late glacial sea level record the increase in sea level from the last glacial maximum has been derived from a siliciclastic system on the tectonically stable sunda shelf in southeast asia the time from 21 to 14 thousand calendar years before the present has been poorly covered in other records the record generally confirms sea level reconstructions from coral reefs the rise of sea level during meltwater pulse 1a was as much as 16 meters within 300 years 14 6 to 14 3 thousand years ago

holocene sea level and climate change in the black sea multiple marine incursions related to freshwater discharge events abstract repeated marine invasions of the black sea during the holocene have been inferred by many eastern scientists as resulting from episodes of marine inflow from the mediterranean beneath a brackish outflow from the black sea we support this scenario but a fundamental question remains what caused the repeated marine invasions we offer an hypothesis for the repeated marine invasions of the black sea based on 1 the overall similarity of sea level curves from both tectonically quiescent and active margins of the black sea and their similarity to a sequence stratigraphic record from the us mid atlantic coast the similarity of the records from two widely separated regions suggests their common response to documented holocene climate ocean atmosphere reorganizations coolings 2 the fact that in the modern black sea freshwater runoff from surrounding rivers dominates over evaporation so that excess runoff might have temporarily raised black sea level although the black sea would have remained brackish following the initial invasion of the black sea by marine mediterranean waters through the marmara sea in the early holocene repeated marine incursions were modulated or perhaps even caused by freshwater discharge to the black sea climatic amelioration warming following each documented ocean atmosphere reorganization during the holocene likely shifted precipitation patterns in the surrounding region and caused mountain glaciers to retreat increasing freshwater runoff above modern values and temporarily contributing to an increase of black sea level freshwater to brackish water discharges into the black sea initially slowed marine inflow but upon mixing of runoff with more marine waters beneath them and their eventual exit through the bosphorus marine inflow increased again accounting for the repeated marine invasions the magnitude of the hydrologic and sea level fluctuations became increasingly attenuated through the holocene as reflected by black sea level curves

fault roughness at seismogenic depths from lidar and photogrammetric analysis fault surface roughness is a principal factor influencing earthquake mechanics and particularly rupture initiation propagation and arrest however little data currently exist on fault surfaces at seismogenic depths here we investigate the roughness of slip surfaces from the seismogenic strike slip gole larghe fault zone exhumed from ca 10 km depth the fault zone exploited pre existing joints and is hosted in granitoid rocks of the adamello batholith italian alps individual seismogenic slip surfaces generally show a first phase of cataclasite production and a second phase with beautifully preserved pseudotachylytes of variable thickness we determined the geometry of fault traces over almost five orders of magnitude using terrestrial laser scanning lidar ca 500 to 1 10 m is not anisotropic and less evolved than at smaller scales these observations are consistent with an evolution of roughness due to fault surface processes that takes place only at scales smaller or comparable to the observed net slip differences in roughness evolution between shallow and deeper faults the latter showing evidences of seismic activity are interpreted as the result of different weakening versus induration processes which also result in localization versus delocalization of deformation in the fault zone from a methodological point of view the technique used here is advantageous over direct measurements of exposed fault surfaces in that it preserves in cross section all of the structures which contribute to fault roughness and removes any subjectivity introduced by the need to distinguish roughness of original slip surfaces from roughness induced by secondary weathering processes moreover offsets can be measured by means of suitable markers and fault rocks are preserved hence their thickness composition and structural features can be characterised providing an integrated dataset which sheds new light on mechanisms of roughness evolution with slip and concomitant fault rock production

roughness of fault surfaces over nine decades of length scales 1 we report on the topographic roughness measurements of five exhumed faults and thirteen surface earthquake ruptures over a large range of scales from 50 m to 50 km we used three scanner devices lidar laser profilometer white light interferometer spanning complementary scale ranges from 50 m to 10 m to measure the 3 d topography of the same objects i e five exhumed slip surfaces vuache sillingy bolu corona heights dixie valley magnola a consistent geometrical property i e self affinity emerges as the morphology of the slip surfaces shows at first order a linear behavior on a log log plot where axes are fault roughness and spatial length scale covering five decades of length scales the observed fault roughness is scale dependent with an anisotropic self affine behavior described by four parameters two power law exponents h constant among all the faults studied but slightly anisotropic h 0 58 0 07 in the slip direction and h 0 81 0 04 perpendicular to it and two pre factors showing variability over the faults studied for larger scales between 200 m and 50 km we have analyzed the 2 d roughness of the surface rupture of thirteen major continental earthquakes these ruptures show geometrical properties consistent with the slip perpendicular behavior of the smaller scale measurements our analysis suggests that the inherent non alignment between the exposed traces and the along or normal slip direction results in sampling the slip perpendicular geometry although a data gap exists between the scanned fault scarps and rupture traces the measurements are consistent within the error bars with a single geometrical description i e consistent dimensionality over nine decades of length scales

further evidence of abrupt holocene drowning of the black sea shelf a 1999 survey of the black sea continental shelf off the north central turkish seaport of sinop using a side scan sonar small remotely operated vehicles and a series of dredge lowerings located inspected and sampled an exposed high energy paleoshoreline at a depth of 155 m radiocarbon dating of mollusk shells collected from this ancient beach revealed that the marine flooding of the black sea took place between 7460 and 6820 yr b p all ages are reported in radiocarbon years not calendar years without correction for reservoir age or dendro calibration changing it from a lacustrine to marine environment this relic surface remained in contact with the bottom waters of the black sea for a long period of time before being draped by a thin layer of sapropel mud wood samples recovered from this same location were very well preserved and yielded dates as old as 3580 yr b p q 2000 elsevier science b v all rights reserved

earthquake nucleation on rough faults earthquake nucleation is currently explained using rate and state stability analysis which successfully models the behavior of laboratory simulated faults with constant thickness gouge layers however roughness is widely observed on natural faults and its influence on earthquake nucleation is little explored here we conduct frictional sliding experiments with different roughness on granite samples at upper crustal conditions 30 200 mpa we observe a wide range of behaviors from stable sliding to stick slip depending on the combination of roughness parameters and normal stress stick slip is repeatedly observed in velocity strengthening regimes and increases in normal stress stabilize slip these features are not fully predicted by current stability analysis we derive a new instability criterion that matches our observations based on fracture energy considerations and the size of weak patches created by fault roughness

the ancient harbour parasequence anthropogenic forcing of the stratigraphic highstand record abstract unique chronostratigraphic similarities are observed in recent geoscience literature on ancient mediterranean harbours from these empirical port data a clear pattern of millennial anthropogenic forcing marked by a fining up sequence can be discerned in coastal stratigraphy the stratigraphic peculiarity of this artificial or human modified parasequence leads us to define a new working model the ancient harbour parasequence

from sub rayleigh to supershear ruptures during stick slip experiments on crustal rocks supershear earthquake ruptures propagate faster than the shear wave velocity although there is evidence that this occurs in nature it has not been experimentally demonstrated with the use of crustal rocks we performed stick slip experiments with westerly granite under controlled upper crustal stress conditions supershear ruptures systematically occur when the normal stress exceeds 43 megapascals mpa with resulting stress drops on the order of 3 to 25 mpa comparable to the stress drops inferred by seismology for crustal earthquakes in our experiments the sub rayleigh to supershear transition length is a few centimeters at most suggesting that the rupture of asperities along a fault may propagate locally at supershear velocities in turn these sudden accelerations and decelerations could play an important role in the generation of high frequency radiation and the overall rupture energy budget

from slow to fast faulting recent challenges in earthquake fault mechanics faultsthin zones of highly localized shear deformation in the earthaccommodate strain on a momentous range of dimensions millimetres to hundreds of kilometres for major plate boundaries and of ti

an abrupt drowning of the black sea shelf abstract during latest quaternary glaciation the black sea became a giant freshwater lake the surface of this lake drew down to levels more than 100 m below its outlet when the mediterranean rose to the bosporus sill at 7 150 yr bp 1 saltwater poured through this spillway to refill the lake and submerge catastrophically more than 100 000 km2 of its exposed continental shelf the permanent drowning of a vast terrestrial landscape may possibly have accelerated the dispersal of early neolithic foragers and farmers into the interior of europe at that time

tidal marsh stratigraphy sea level change and large earthquakes i a 5000 year record in washington u s a abstract many of the estuaries of the pacific northwest of the u s a and canada contain stratigraphic sequences typified by alternating peat mud couplets recent studies in this region interpret such couplets as the product of repeated large magnitude s or 9 earthquakes on the cascadia subduction zone the resultant pattern of land level movements is described by a model the earthquake deformation cycle of coseismic land subsidence followed by land uplift during interseismic strain accumulation however peat mud couplets similar to those recorded in the pacific northwest are found on other less tectonically active temperate latitude coasts such as northwest europe and the atlantic coast of the u s a where they have been interpreted as the product of non seismic coastal processes in this paper we apply the methods and scientific framework common to sea level investigations in northwest europe to a sequence of peat mud couplets recorded in the lower johns river an estuary in southern washington to provide a test of the earthquake deformation cycle stratigraphic investigations of the intertidal sediments along the lower johns river using lithological pollen diatom and foraminiferal data show evidence for eight coastal submergence events during the last 5000 years to evaluate the earthquake deformation cycle we assess the lateral extent of peat mud couplets the synchroneity of submergence the presence of tsunami deposits accompanying submergence and the suddenness and amount of submergence each submergence is shown to be accompanied by changes in coastal sedimentation broadly commensurate with those predicted by the earthquake deformation cycle demonstrating the continued intermittent seismic activity of the cascadia subduction zone throughout the mid and late holocene quantitative analyses of contemporary and fossil biostratigraphic data using twinspan and detrended correspondence analysis enable us to estimate the magnitude of submergence accompanying each peat mud couplet one event was accompanied by submergence of about 1 5 m or more four events by intermediate submergence of about 1 0 5 m and a further three events by submergence of

mud volcanoes the most important pathway for degassing deeply buried sediments abstract this paper discusses the nature of the phenomenon of mud volcanism with respect to degassing of deeply buried sediments mud volcanoes are defined as geological structures and their main elements are described based on the nature of activity mud volcanoes are grouped in to three main types and the relationship between each type and corresponding morphological expression is discussed the presented up to date data of the world geographical distribution of mud volcanoes show that they approximate to 1800 individuals a detail overview of geological environments in which they occur helps to deduce some necessary conditions for mud volcano formation the basic mechanisms of mud volcano formation are discussed specifically the fluid pressure hypothesis and some triggering events are identified the most common investigation approach and some criteria for recognizing of a submarine mud volcano on side scan sonar records and seismic sections are given mud volcanism in the mediterranean ridge an accretionary complex and black sea abyssal plane a back ark basin with tectonic regime of extension are described as case studies to show variety in morphology and common factors in development of mud volcanoes the manifestation of continuous gas migration through mud volcanoes is clarified and the attempt made to quantify the gas release shows that mud volcanoes are one of the significant natural sources of atmospheric methane emitting a total amount of about 10 3 to 12 6 tg annually

western versus eastern black sea tectonic evolution pre rift lithospheric controls on basin formation abstract we demonstrate the key role of pre rift rheology on the kinematics of basin formation in the western and eastern black sea basins constraints on modelling results are provided by a large data set based on more than 50 000 km of multichannel seismics offshore and onshore wells regional gravity and magnetic surveys refraction seismics and field studies the model supports the presence of important differences in the thickness and in the thermal state of the lithosphere which rifted to form the western middle barremian and the eastern middle paleocene black sea subbasins a 200 km and a 80 km thick pre rift lithosphere appear to have driven the deformation in the western and in the eastern black sea respectively differences in the geometry and in the mechanical properties of the pre rift lithosphere have a strong control on the depth of necking and thus on the basin morphology the model sheds light on palaeotectonic and palaeogeographic reconstructions duration of rifting events location of subsiding areas and erosional surfaces the western and the eastern parts of the black sea appear to be two distinct basins characterised by different evolutionary paths determined by different pre rift conditions

numerical modelling of regional neotectonic movements in the northern black sea abstract the paper examines the manifestation of tectonic processes related to the neogene and recent subsidence of the black sea margin and uplift of the crimea mountains as well as current seismicity in the southern crimea a 2 d finite element model based on a seismic line across the northern black sea and the crimean mountains that predicts the present day tectonic velocity field using the available neotectonic data as boundary conditions has been developed the model results indicate that the observed structure and tectonic motions cannot be explained by forces imposed on the external side boundaries of the model only rather movements consisting of upwelling beneath the black sea and subsidence under the crimea interpreted as the effects of mantle processes are necessary to explain the observed topographic evolution of the area zones where the ratio of the calculated shear stress to calculated pressure is greatest correspond to the position of the southern coast fault that controls the seismicity of the northern black sea margin

tidal wetland record of holocene sea level movements and climate history abstract paleontological geochemical and lithological indicators of former marine and nonmarine influence are correlated between 13 cores from a tidal wetland wolfe glade on the southeast coast of delaware bay twenty new radiocarbon dates are used to establish the chronostratigraphy of marsh facies sediment iron content weight loss on ignition and remains of plants diatoms and foraminifera known to tolerate specific tidal inundation cycles are used to describe cored facies originating from supratidal intertidal and subtidal salt marsh subenvironments pollen assemblages are used to infer local holocene climate fluctuations and to reconstruct paleoenvironments during marsh evolution the record of paleoclimatology suggests the atlantic chron was warm with variable humidity in the region whereas the subboreal was dominated by cool and humid conditions the subatlantic was warmer and initially dryer with a cool humid phase prior to about 1 ka returning to warmer humid conditions in the last several centuries local relative sea level movements are characterized by five rapid short term episodes when the rate of sea level rise accelerated relative to the rate of marsh aggradation these episodes are recorded by transgressive facies contacts at 5 3 0 2 ka 4 4 0 2 ka 3 25 0 2 ka and 1 8 0 2 ka sidereal years an earlier transgressive facies contact dated 6 9 0 2 ka is probably not the product of a true sea level movement sea level movements are recorded throughout the marsh as palustrine or high marsh peats or peaty overlain by lower intertidal or subtidal marine deposits several features suggest that these episodes are local relative transgressions produced by short term accelerations in the rate of sea level rise relative to marsh aggradation the contemporaneity and apparent suddenness of marine inundations the sequence of facies indicating marine drowning the presence of similar events in marshes elsewhere in delaware bay and the marsh wide extent of indicative facies transitions we propose that the rapid and frequent sea level movements observed in wolfe glade are the result of surges and relaxations in the gulf stream and associated spin up and partial collapse of the north atlantic gyre in response to winds generated by changes in the north atlantic atmospheric thermal gradient associated with holocene climate fluctuations

young danube delta documents stable black sea level since the middle holocene morphodynamic paleogeographic and archaeological implications new radiocarbon and optical dates show that the holocene danube delta started to build out of a black sea embayment 5200 yr ago delta lobe development phases differ by as much as 5 k y from previously proposed ages the new chronology allows for a better understanding of the danube delta paleogeography includ ing the demise of istria the main ancient greek roman city in the region prior reconstructions of sea level in the black sea inferred fluctuations to 15 m in range however stratigraphy of beach ridg es in the delta shows that the relative black sea level for the past 5 k y was stable in the danube delta region within 2 m and 1 5 of the current level hydroisostatic effects related to a proposed catastrophic reconnection of the black sea to the world ocean in the early holocene may have been responsible for the sea level reaching the highstand earlier than estimated by models the new sea level data suggest that submergence at several ancient settle ments around the black sea may be better explained by local fac tors such as subsidence rather than by basin wide sea level fluctuations

new constraints on the rapid crustal motion of the aegean region recent results inferred from gps measurements 1993 1998 across the west hellenic arc greece abstract in this paper we present the most recent observations of crustal motion across the entire west hellenic arc wha these are based on repeated gps measurements carried out in the period from 1993 to 1998 the results are presented in terms of trajectories and rates relative to eurasia within these five years southwestern greece has moved to the southwest by an average rate of 30 mm a increasing from 10 mm a at the island of lefkada in the center of the ionian islands to nearly 40 mm a along the southwest part of the peloponnesus and to 35 mm a on the islands of crete and gavdhos the data provide strong evidence that distributed shear strain starts at the kephalonia fault zone kfz were an anomalously high earthquake activity is also observed a striking interruption of the motion is seen at the island of strofades at the southwest leading edge of the wha where a south oriented displacement of 12 cm was detected coincident with the m 6 4 strofades earthquake of nov 18 1997

constraints from fault roughness on the scale dependent strength of rocks principal slip surfaces in faults have measurable roughness generated during slip the roughness both records previous events and poses the boundary conditions for future rupture digital high precision roughness data are now available at the field scale tens of centimeters to tens of meters for at least 22 faults and at the laboratory scale millimeters to tens of centimeters for a subset of these we quantify the slip surface roughness by measuring the aspect ratio which is the average asperity height divided by the profile length higher aspect ratios indicate rougher surfaces from the field studies two major trends have emerged 1 fault surface roughness lies in a restricted range with aspect ratios in the slip parallel direction of 0 07 0 5 for profiles of 1 m length and 2 fault surfaces are rougher at small scales than large ones these features can both be interpreted as fingerprints of scale dependent strength which sets a limit to the aspect ratio of the surface the measurements imply that shear strength scales with the observation scale l as l 0 4 the new understanding of the physical controls on roughness allows generalization of the extant measurements of a wide array of faults

rupture preparation process controlled by surface roughness on meter scale laboratory fault abstract we investigate the effect of fault surface roughness on rupture preparation characteristics using meter scale metagabbro specimens we repeatedly conducted the experiments with the same pair of rock specimens to make the fault surface rough we obtained three experimental results under the same experimental conditions 6 7 mpa of normal stress and 0 01 mm s of loading rate but at different roughness conditions smooth moderately roughened and heavily roughened during each experiment we observed many stick slip events preceded by precursory slow slip we investigated when and where slow slip initiated by using the strain gauge data processed by the kalman filter algorithm the observed rupture preparation processes on the smooth fault i e the first experiment among the three showed high repeatability of the spatiotemporal distributions of slow slip initiation local stress measurements revealed that slow slip initiated around the region where the ratio of shear to normal stress was the highest as expected from finite element method fem modeling however the exact location of slow slip initiation was where became locally minimum probably due to the frictional heterogeneity in the experiment on the moderately roughened fault some irregular events were observed though the basic characteristics of other regular events were similar to those on the smooth fault local stress data revealed that the spatiotemporal characteristics of slow slip initiation and the resulting drop for irregular events were different from those for regular ones even under similar stress conditions on the heavily roughened fault the location of slow slip initiation was not consistent with anymore because of the highly heterogeneous static friction on the fault which also decreased the repeatability of spatiotemporal distributions of slow slip initiation these results suggest that fault surface roughness strongly controls the rupture preparation process and generally increases its complexity with the degree of roughness

frictional melt homogenisation during fault slip geochemical textural and rheological fingerprints abstract volcanic environments often represent structurally active settings where strain localisation can promote faulting frictional deformation and subsequent melting along fault planes such frictional melting is thermodynamically a disequilibrium process initiated by selective melting of individual mineral phases and softening of volcanic glass at its glass transition as a response to rapid frictional heating the formation of a thin melt layer on a fault plane surface can drastically accelerate or terminate slip during fault motion a comprehensive understanding of the physical and chemical properties of the frictional melt is required for a full assessment of slip mechanisms as frictional rheology depends on the contributions from selectively melted mineral and glass phases as well as the physical effects of restite fragments suspended in the frictional melt here we experimentally investigate the impact of host rock mineralogy on the compositional and textural evolution of a frictional melt during slip high velocity rotary shear hvr experiments were performed under controlled volcanically relevant coseismic conditions 1 m s 1 slip rate and 1 mpa normal stress using three intermediate dome lavas with contrasting mineral assemblages sampled from volcanic systems where fault friction is evident 1 an amphibole bearing andesite soufriere hills volcano montserrat 2 an amphibole poor dacite santiaguito dome complex guatemala and 3 an amphibole free andesite volcan de colima mexico for each sample five hvr experiments were terminated at different stages of frictional melt evolution namely 1 at the onset of melting 2 upon formation of a steady state melt layer and 3 after 5 m 4 10 m and 5 15 m of slip at steady state conditions progressive mixing and homogenisation of selective single phase melts within the frictional melt layer through double diffusion convection demonstrates the control of melt composition on slip behaviour amphiboles melted preferentially leading to consistently lower shear stress 1 mpa less than amphibole poor samples and pronounced shear weakening during the frictional melting of amphibole bearing lavas the results highlight the implications of mineral assemblages on fault slip including conduit flow processes which may influence the style of eruptions and run out distances of rapid granular flows

biological evidence of sea level rise during the last 4500 years on the rocky coasts of continental southwestern france and corsica on the rocky coasts of the northwestern mediterranean basin biogenic littoral rims built by the coralline rhodophyte lithophyllum lichenoides develop whose remains may be preserved for millennia when submerged in a rising sea environment these remains can be used as biological indicators of recent sea level variations our survey of the continental coasts of var and bouches du rhone west of marseilles southern france and of northern corsica shows that relative sea level rose about 1 6 m in the study area during the last 4500 years without exceeding the present datum the rate of sea level rise was 0 4 mm per year between 4500 and 1500 yr b p and slowed down to 0 2 mm per year from 1500 yr b p to present time there are also morphological indications of an acceleration of the rate of sea level rise during the last century supporting the evidence of tide gauges regions at the periphery of the above zone alpes maritimes italian border zone and the french and spanish catalonia regions were also surveyed but a weaker development of lithophyllum rims and bad preservation of algal remains led to unconvincing dates which could also be linked to regional tectonic trends

scaling of rock friction constitutive parameters the effects of surface roughness and cumulative offset on friction of gabbro we describe experiments in which large 14 40 cm nominal contact area blocks of gabbro were sheared in a direct shear apparatus at room temperature 5 mpa normal stress and slip velocities from 0 1 to 10 m s the apparatus was servocontrolled using a displacement feedback measurement made directly between the gabbro blocks two surface roughnesses were studied rough produced by sandblasting and smooth produced by lapping with 60 grit and accumulated displacements reached 60 mm measurements of surface topography were used to characterize roughness and asperity dimensions step changes in loading velocity were used to interrogate friction constitutive properties both rough and smooth surfaces showed appreciable displacement hardening the coefficient of friction for rough surfaces was about 0 45 for initial slip and 0 7 after sliding 50 mm smooth surfaces exhibited higher and a greater tendency for unstable slip the velocity dependence of frictiona b and the characteristic friction distanced c show systematic variations with accumulated displacement for rough surfacesa b started out positive and became negative after about 50 mm displacement andd c increased from 1 to 4 m over the same interval for smooth surfaces a b began negative and decreased slightly with displacement andd c was about 2 m independent of displacement for displacements 30 mm rough surfaces exhibit a second state variable with characteristic distance about 20 m the decrease ina b with displacement is associated with disappearance of the second state variable our data indicate thatd c is controlled by surface roughness in a complex way including but not limited to the effect of roughness on contact junction dimensions for bare rock surfaces the data show that simple descriptions of roughness such as rms and peak to trough are not sufficient to inferd c our observations are consistent with a model in whichd c scales with gouge thickness

properties of the 2003 lefkada ionian islands greece earthquake seismic sequence and seismicity triggering on 14 august 2003 lefkada island central ionian was strongly af fected by an mw 6 2 earthquake a dense temporary seismic network was installed one day after and accurately located hundreds of aftershocks that defined in detail the main rupture as well as the activity distribution in the neighboring fault segments the main rupture occupied the northwestern part of the coastline and trends north northeast south southwest in agreement with regional tectonics regional network locations were appropriately calibrated using the local network data allowing the relocation of the mainshock and strong m 4 5 or larger aftershocks during the first day intense aftershock activity took place up to 40 km beyond the southern end of the main rupture theoretical static stress changes from the mainshock give a preliminary explanation for the aftershock distribution aside from the main rupture as well as triggering of seismicity in the nearby kefalonia fault providing evidence for future seismic hazard ensuing from this fault

stratigraphic and structural characteristics of the romanian black sea shelf abstract the western black sea basin opened during cretaceous times by back arc rifting in association with a north dipping subduction at the rear of the cretaceous early tertiary pontide volcanic arc the sedimentary wedge developed on the shelf of the romanian black sea sector reflects a complex interplay between large scale rifting uplift of the orogenic flanks large scale post rift subsidence and sea level changes we examine the detailed structural configuration of this sector for a regional correlation with the adjacent offshore in ukraine and bulgaria the evolution of the western black sea basin started in the albian cenomanian times when two extensional phases with significantly different directions n s and subsequently e w lead to the formation of a complex interplay between isolated blocks organised in horsts and grabens generally deepening eastwards superposition of normal faults footwall blocks from the two extensional episodes generated a deeply subsided area with enhanced accommodation space i e the histria depression and consequently recorded a larger thickness of paleogene sediments in the post rift stage re activation of faults and associated folding reflects repeated inversion during the late cretaceous oligocene times associated with subsequent periods of non deposition and or erosion during moments of basin fill exposure these periods of inversion recorded in the black sea are controlled by coeval orogenic deformations taking place in the balkans pontides and the crimean thrust belt sea level fluctuations during the neogene and late alpine tectonics in the neighbouring orogens caused massive sedimentation followed by sediment starvation and or significant erosion large thicknesses of sediments accumulated during the pontian presumably associated with an extensional episode deepening the distal parts of the basin and with differential compaction structures the interpretation of a high quality seismic dataset combined with published data allowed the correlation of major structural units and lineaments defined onshore towards the carpathians with the ones deeply buried below the western black sea basin sediments unit correlations are furthermore used to derive an integrated tectonic image of the western black sea area

the holocene sea level story since 7500 bp lessons from the eastern mediterranean the black and the azov seas abstract this paper addresses the obvious controversy between the so far published sea level curves of the black sea and the mediterranean it starts with a discussion of the methods of reconstructing sea level curves the evaluation of sea level indicators and the application of the radiocarbon dating method at least since 7500 bp when the black sea and the mediterranean were connected both water bodies must have reacted synchronously on glacio eustatic changes it is documented that none of the mediterranean sea level curves shows the major wiggles postulated for the black sea which are supposed to reflect trans and regression cycles the very shallow bathymetric condition of the azov sea and the northern black sea should have led to considerable and traceable shoreline displacements there is neither archaeological nor historical evidence of mid and late holocene regressions of several meters the tectonic setting of the black and azov seas implicates that the tectonic signal often overrides the eustatic one therefore only local sea level curves can be established in this paper based on vibracores a locally valid sea level curve for the taman peninsula is demonstrated layers of paralic peat were used as sea level indicators and for 14 c dating the shape of this curve follows the one known from the mediterranean this study also revealed that the present peninsula of taman evolved out of a former archipelago

crustal velocity and strain rate fields in italy and surrounding regions new results from the analysis of permanent and non permanent gps networks summary we present a new geodetic velocity solution for italy and the surrounding areas obtained from an analysis of continuous and survey mode global positioning system observations collected between 1991 and 2002 we have combined local regional and global networks into a common reference frame velocity solution providing a new detailed picture of the regional scale deformation field in the central mediterranean our velocity estimates are computed with respect to a new stable eurasian reference frame constraining the kinematics of the greater african eurasian plate boundary system in the study area we provide strain rate values for the main seismotectonic districts which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms the southern tyrrhenian area calabria the apennines the southeastern alps the southern dinarides and the albanides display deformation rates at the order of 20 30 nanostrain yr 1 the corsica sardinia block moves according to eurasian plate motions and there is no indication that the opening of the tyrrhenian is still active the pelagian and sicilian domains are separated by a northwest southeast discontinuity the sicily channel rifted area and marginally significant relative motion between the pelagian plateau and the african plate is also observed the southern tyrrhenian is affected by north south compression and accommodates up to 50 per cent of the africa eurasia relative plate motion whereas the calabrian arc exhibits 2 mm yr 1 northwest southeast extension the observed deformation pattern suggests the presence of a major approximately north south tectonic discontinuity separating the sicilian and calabrian domains an extensional boundary observed along peninsular italy coincides with the distribution of seismogenic faults along the axis of the apennines this boundary separates a tyrrhenian and an adriatic domain with diverging velocities orientated north nnw ward and northeastward respectively the apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr 1 and only in the outer northern apennines indications of active shortening are observed insignificant deformation is observed in the western po plain and the western alps while the central and eastern alps display north south shortening the eastern adriatic domain is shortening perpendicular to the dinaric front with strain rates increasing from north to south the locus of collision between the aegean balkan system and the adriatic and ionian domains is marked by the kephalonia fault system which accommodates up to 20 1 mm yr 1 of right lateral motion the deformation pattern observed in the peri adriatic domain is well described by a counter clockwise rotation of the adriatic microplate around a pole located in the western alps

effects of physical fault properties on frictional instabilities produced on simulated faults laboratory studies of large scale simulated faults show that physical properties of the fault specifically normal stress and fault roughness significantly influence the unstable shear failure behavior of the fault in addition the experiments provide insights into important length scaling effects that are useful for assessing concepts such as critical crack length or rupture nucleation dimension stick slip shear failures have been generated along a 2 m long simulated fault in a block of sierra white granite experiments were conducted at normal stresses between 0 6 and 4 mpa with two different prepared roughnesses of the simulated fault a smooth fault with a profilometer measured roughness of 0 2 m and a rough fault with a measured roughness of 80 m high speed records of shear strains and slip velocities clearly show both the propagation of the stick slip failures and details of the local deformations and motions from which slip weakening of the fault at the onset of sliding can be resolved both the dynamic stress drops of the stick slip events and the apparent fracture energies of the events determined from the records of the fault slip weakening increase with increasing normal stress although critical slip weakening displacements are insensitive to normal stress they increase with increased fault roughness such that the apparent fracture energies are also larger on the rough fault than on the smooth fault slip velocities in these experiments are influenced by roughness and are proportional to stress drop although the onset of slip is sharply defined the termination of slip is more gradual without a clear stopping phase measured rupture velocities on the rough fault are lower than those on the smooth fault when a length scale based on rupture nucleation dimensions directly proportional to critical displacements is introduced the data suggest that at fault lengths close to the nucleation lengths rupture velocity and slip velocity increase with increasing fault length

earthquake nucleation size evidence of loading rate dependence in laboratory faults recent gps observations of major earthquakes such as the 2014 chile megathrust show a slow pre slip phase releasing a significant portion of the total moment ruiz et al 2014 despite advances from theoretical stability analysis rubin ampuero 2005 ruina 1983 and modeling kaneko carpenter nielsen 2017 it is not fully understood what controls the prevalence and the amount of slip in the nucleation process here we present laboratory observations of slow slip preceding dynamic rupture where we observe a dependence of nucleation size and position on the loading rate laboratory equivalent of tectonic loading rate the setup is composed of two polycarbonate plates under direct shear with a 30 centimeters long slip interface the results of our laboratory experiments are in agreement with the pre slip model outlined by ellsworth and beroza 1995 and observed in laboratory experiments latour schubnel nielsen madariaga vinciguerra 2013 nielsen taddeucci vinciguerra 2010 ohnaka kuwahara 1990 which show a slow slip followed by an acceleration up to dynamic rupture velocity however further complexity arises from the effect of 1 rate of shear loading and 2 inhomogeneities on the fault surface in particular we show that when the loading rate is increased from 10 2 mpa s 1 to 6 mpa s 1 the nucleation length can shrink by a factor of three and the rupture nucleates consistently on higher shear stress areas the nucleation lengths measured fall within the range of the theoretical limits lb and l derived by rubin and ampuero 2005 for rate and state friction laws

geoarchaeology of sidon s ancient harbours phoenicia abstract geoarchaeological data from sidon s ancient harbour areas elucidate six evolutionary phases since the bronze age 1 at the time of sidon s foundation during the third millennium bc medium sand facies show the city s northern and southern pocket beaches to have served as proto harbours for middle to late bronze age societies 2 towards the end of the late bronze age and the early iron age expanding international trade prompted coastal populations into modifying these natural anchorages in sidon s northern harbour transition from shelly to fine grained sands is the earliest granulometric manifestation of human coastal modification the lee of zire island was also exploited as a deep water anchorage or outer harbour at this time 3 although localised sediments evoke developed port infrastructure during the phoenician and persian periods high resolution reconstruction of the northern harbour s iron age history is problematic given repeated dredging practices during the roman and byzantine periods 4 fine grained silts and sands in the northern harbour are coeval with advanced roman engineering works significantly deforming the coastal landscape bio and lithostratigraphical data attest a leaky lagoon type environment indicative of a well protected port 5 the technological apogee of sidon s northern harbour is recorded during the late roman and byzantine periods translated stratigraphically by a plastic clays unit and brackish lagoon fauna 6 a final semi abandonment phase comprising coarse sand facies concurs silting up and a 100 150 m progradation of the port coastline after the seventh century ad we advance three hypotheses to explain these stratigraphic data namely cultural tectonic and tsunamogenic finally our results are compared and contrasted with research undertaken in sidon s sister harbour tyre

asperity generation and its relationship to seismicity on a planar fault a laboratory simulation author s selvadurai pa glaser sd abstract the authors 2016 published by oxford university press on behalf of the royal astronomical society earthquake faults and all frictional surfaces establish contact through asperities a detailed knowledge of how asperities form will enable a better understanding of the manner in which they communicate during foreshock failure sequences that are observed leading to the larger main shock we present results of experiments where a pressure sensitive film was used to map size and measure the magnitudes of the normal stresses at asperities along a seismogenic section of a laboratory simulated fault we measured seismicity acoustically and foreshocks were found to be the result of localized asperity failure during the nucleation phase of gross fault rupture since surface roughness plays an important role in how asperities are formed two hurst exponents were measured to characterize a highly worn interface using roughness profiles i long wavelength estimates h 0 45 and ii short wavelength estimates h 0 8 1 2 the short wavelength roughness estimates were computed at the scale of single asperity junction points macroscopically the number of asperities and real contact area increased with additional application of normal force while the mean normal stress remained constant the ratio of real to nominal contact area was low ranging from 0 02 l ar a0 l 0 05 predicting that the asperities should be elastically independent of each other results from the pressure sensitive film showed that asperities were closely spaced and could not be treated as mechanically independent larger asperities carried both higher levels of average normal stress and higher levels of normal stress heterogeneity than smaller ones using linear stability theorem the critical slip distance on foreshocking asperities was estimated to be d0 0 65 3 m the critical slip distance d0 was 1 8 11 5 per cent of the premonitory slip needed to initiate gross fault rupture of the interface 20 40 m and the overall slip necessary to initiate gross fault rupture was on the order of the average asperity diameter 52 m foreshocks may be due to a change in the critical slip distance at localized sections of the fault caused by the two distinct roughness profiles measured at short and long length scales

modelling holocene relative sea level observations from the caribbean and south america abstract holocene data from the caribbean and the atlantic coast of south america have been critically assessed and a subset of the best quality data are presented these data cover a large north south geographic extent and display a distinct spatial variation we make the first comparisons of this data set to predictions based on a realistic model of glaciation induced sea level change with the main aims of understanding the cause of the observed spatial trend and estimating a eustatic signal for the holocene the spatial variation is dominated by the influence of the ice and ocean mass redistribution on sea level change with the ice induced effect dominating the observed north south trend a best fitting model is applied to estimate a holocene eustatic signal from the observations we find that the model corrected data are consistent with a relatively rapid rise of 7 8 mm yr in the early holocene with a marked reduction in this rate around 7 cal kyr bp from this time until present the model corrected data suggest that the volume of mass transfer between ice sheets and oceans was no more than 1 m eustatic sea level equivalent

deltas south of the bosphorus strait record persistent black sea outflow to the marmara sea since 10 ka at the southern exit of the bosphorus strait in the northeastern marmara sea high resolution seismic profiles reveal two lobate progradational delta lobes in modern water depths of v40 65 m the younger delta was active from v10 to 9 ka based on radiocarbon dates of equivalent prodelta deposits and the elevation of its topset to foreset transition the topset to foreset transition climbs in the seaward direction because the delta prograded into a rising sea low abundances of marine fauna and flora in the 10 9 ka interval support a deltaic interpretation there are no rivers in the area that could have fed the delta instead all evidence points to the strait itself as the source of sediment and water when this outflow was strongest v10 6 6 0 ka sapropels accumulated in basinal areas of both the aegean and marmara seas benthic foraminiferal and dinoflagellate cyst data from contemporary deposits elsewhere in the marmara sea point to the continual presence through the holocene of a surface layer of brackish water that we ascribe to this same outflow from the black sea through the bosphorus strait by v9 1 8 5 ka two layer flow developed in the bosphorus strait as global sea level continued to rise and the sediment supply to the younger delta was cut off because the outflowing black sea water ceased to be in contact with the floor of the strait the older delta lobe lies below a prominent lowstand unconformity and is tentatively interpreted to have formed from v29 5 to 23 5 ka oxygen isotopic stage 3 when the marmara sea stood at v355 m and a second sapropel accumulated in deep basinal areas crown copyright 2002 elsevier science b v all rights reserved

modulation of fault strength during the seismic cycle by grain size evolution around contact junctions abstract earthquake prediction is fundamentally hampered by insufficient knowledge of the constitutive behavior of faults laboratory and theoretical work by dieterich 1978 and ruina 1983 formed the basis of rate and state friction a constitutive framework that captures the healing and weakening of frictional contacts the rate and state law successfully explains the frictional behavior of a wide range of rocks and many phenomena associated with fault slip the physics underlying the rate and state friction law is not fully understood but it is generally accepted that several micro mechanisms operate depending on the texture maturity fluid content and other physical and kinematic conditions of the fault here i formulate a constitutive framework that unifies a number of laboratory experiments on silicate rocks and the gouges derived from these rocks that describe the effect of grain size temperature real area of contact gouge thickness and fault roughness fundamental to the model is that fault strength is controlled by the area of the interfacial contact junctions that support the shear and normal loads the curvature of asperities weakly controls the area of their contact junction and the resulting fault strength as a result the dynamics of grain size evolution around micro asperities enables the seismic cycle the model quantitatively explains the correlation between the characteristic weakening distance and the gouge thickness marone and kilgore 1993 the correlation of the static friction coefficient with the rate dependence parameters ikari et al 2011 the dependence of frictional resistance to sub solidus temperatures chester 1994 and predicts a range of grain sizes that is compatible with observations at exposed fault zones however the dynamics of grain size evolution is still challenging to verify experimentally the model features a regularization at vanishing slip speeds that implies distinct dynamics at low strength for friction coefficients lower than 0 1 seismic cycle simulations predict the emergence of frictional instabilities with complex source time functions this is a significant departure from the predictions of rate and state friction that is most relevant to the dynamics of decollements serpentinized shear zones and other low strength faults

influence of fault roughness on surface displacement from numerical simulations to coseismic slip distributions field studies have characterized natural faults as rough nonplanar surfaces at all scales fault roughness induces local stress perturbations during slip which dramatically affect rupture behavior resulting in slip heterogeneity however the relation between fault roughness and slip heterogeneity remains a key knowledge gap between current numerical and field studies in this study we analyze numerical simulations of earthquake rupture to determine how roughness influences final slip using a rupture catalog containing thousands of dynamic rupture simulations on band limited self similar fractal fault profiles with varying roughness and background shear stress levels we quantify how fault roughness affects the spectral characteristics of the resulting slip distribution we find that slip distributions become increasingly more self affine that is containing more short wavelength fluctuations as compared to the self similar fault profiles as roughness increases we also find that at very short wavelengths 1km the fractal dimension of the slip distributions dramatically changes with increasing roughness background shear stress

last glacial holocene paleoceanography of the black sea and marmara sea stable isotopic foraminiferal and coccolith evidence multi proxy data and radiocarbon dates from several key cores from the black sea and marmara sea document a complex paleoceanographic history for the last v30 000 yr the marmara sea was isolated from both the black sea and the aegean sea during glacial periods when global sea level lowering subaerially exposed the shallow sills at the straits of bosphorus and dardanelles i e lake stage and reconnected through both straits during interglacial periods when rise of global sea level breached the shallow sills i e gateway stage micropaleontological data show that during the lake stage the surface water masses in both the marmara sea and black sea became notably brackish however during the gateway stages there was a low salinity surface layer and normal marine water mass beneath two sapropel layers are identified in the marmara sea cores sapropels m2 and m1 were deposited between v29 5 and 23 5 ka and v10 5 and 6 0 ka respectively micropaleontological and stable isotopic data show that the surface water salinities were reduced considerably during the deposition of both sapropel layers m2 and m1 and calculation using planktonic foraminiferal transfer functions shows that sea surface temperatures were notably lower during these intervals the presence of fauna and flora with black sea affinities and the absence of mediterranean fauna and flora in sapropels m1 and m2 strongly suggest that communication existed with the black sea during these times a benthic foraminiferal oxygen index shows that the onset of suboxic conditions in the marmara sea rapidly followed the establishment of fully marine conditions at v11 10 5 ka and are attributed to black sea outflow into the marmara sea since 10 5 ka these suboxic conditions have persisted to the present the data discussed in this paper are completely at odds with the flood hypothesis of ryan et al 1997 and ryan and pitman 1999 crown copyright 2002 elsevier science b v all rights reserved

experimental and modeling study of the effect of fault roughness on dynamic frictional sliding abstract friction governs many processes in nature from the motion of glaciers and landslides to tremors and earthquakes the roughness of the sliding interfaces presumably affects their dynamics in particular the condition for stable or unstable sliding we investigate this issue by modeling numerically tri axial stick slip experiments on westerly granite samples with different levels of roughness the model accounts for surface roughness at the millimeter scale and assumes rate and state friction with enhanced dynamic weakening it reproduces key characteristics observed in the experiments such as sequences of fast stick slip events for smooth surface and sequence of slow slip events with small stress drop followed by a large stress drop unstable slip event for the rough interface the increase in loading stiffness due to the additional resistance from roughness can explain the initial slow slip the fast unstable event may be the result of the higher critical stiffness due to the increase of local normal tractions with slip as well as of the reduction of the loading stiffness due to contacts losses the study allows examining numerically the relationship between the frictional behavior on the interface and the apparent friction estimated from external loads we find that because of dynamic overshoot the reduction in apparent friction is larger than that of the actual friction coefficient on the interface

scaling of the shear rupture process from nucleation to dynamic propagation implications of geometric irregularity of the rupturing surfaces a series of systematic high resolution laboratory experiments have been performed on the nucleation of propagating slip failure on preexisting faults having different surface roughnesses to demonstrate how the size scale and duration of shear rupture nucleation are affected by geometric irregularity of the rupturing surfaces on the basis of the experimental results it has been discussed theoretically how consistently scale dependent physical quantities inherent in shear rupture are scaled the experiments led to conclusive results that the nucleation process consists of two phases phase i an initial quasi static phase and phase ii a subsequent accelerating phase and that the nucleation process is greatly affected by geometric irregularities on the rupturing surfaces in phase i the rupture grows at a slow steady speed which is independent of the rupture growth length l in contrast during phase ii the rupture develops at accelerating speeds v which increase with an increase in l obeying a power law v vs l c n where vs is the shear wave velocity c is the characteristic length representing the geometric irregularity of the fault surfaces and and n are constants 8 87 10 29 and n 7 31 scale dependency of scale dependent physical quantities including the nucleation zone size and its duration is commonly ascribed to scale dependency of the slip dependent constitutive law parameter dc which is in turn governed by c it has been discussed that a unified comprehension can be provided for shear rupture of any size scale if the constitutive law for shear rupture is formulated as a slip dependent law

slip on wavy frictional faults is the 3rd dimension a sticking point abstract the formulation for the 3d triangular displacement discontinuity boundary element method with frictional constraints is described in detail its accuracy in comparison to analytical solutions is then quantified we show how this can be used to approximate stress intensity factors at the crack tips using this method we go on to quantify how slip is reduced on fault surfaces with topography where the asperities are approximated as a sinusoidal waveform i e corrugations we use stress boundary conditions compressive orientated such that frictional contacts shear we show that slip reductions relative to planar faults for 2d line and 3d penny shaped crack models are comparable within 10 when slip is perpendicular to the corrugations using the 3d model we then show how slip is reduced more when corrugation wavelengths are doubled compared to the reduction due to corrugation misalignment with the slip direction when slip is parallel with the corrugation alignment we show that reducing the out of plane stress from the normal traction acting on the fault when planar to that resolved on a perpendicular plane has the same effect as halving the length of the corrugation waveform in terms of slip reduction for a given amplitude

the formation of coastal peat marshes under an upward tendency of relative sea level the upward growth of a tidal mudflat marsh within the tidal frame is determined theoretically by the rates of minerogenic sediment supply organogenic sediment supply long range sediment compaction and movement of relative sea level where the movement of relative sea level is upward a marsh can achieve a state of dynamic equilibrium in which the composition of the sediment accumulating on its surface is governed by the balance between the rates of organogenic supply and sea level change a peat organogenic marsh should arise where the former rate roughly equals or exceeds the latter a minerogenic marsh should form where the rate of sea level rise is dominant even though the absolute availability of mineral fine sediment may be so high as to appear to suggest that build up to extreme tidal levels where vegetation would dominate should have occurred

precursory changes in seismic velocity for the spectrum of earthquake failure modes temporal changes in seismic velocity during the earthquake cycle have the potential to illuminate physical processes associated with fault weakening and connections between the range of fault slip behaviors including slow earthquakes tremor and low frequency earthquakes1 laboratory and theoretical studies predict changes in seismic velocity prior to earthquake failure2 however tectonic faults fail in a spectrum of modes and little is known about precursors for those modes3 here we show that precursory changes of wave speed occur in laboratory faults for the complete spectrum of failure modes observed for tectonic faults we systematically altered the stiffness of the loading system to reproduce the transition from slow to fast stick slip and monitored ultrasonic wave speed during frictional sliding we find systematic variations of elastic properties during the seismic cycle for both slow and fast earthquakes indicating similar physical mechanisms during rupture nucleation our data show that accelerated fault creep causes reduction of seismic velocity and elastic moduli during the preparatory phase preceding failure which suggests that real time monitoring of active faults may be a means to detect earthquake precursors

gps derived coseismic displacements associated with the 2001 skyros and 2003 lefkada earthquakes in greece abstract greece is characterized by high seismotectonic activity extended global positioning system gps reoccupation and continuous networks have been measured in order to study the crustal motion and deformation in this region with particular interest in earthquake related effects in this article we present gps derived coseismic displacements in greece caused by the m s 6 6 2001 skyros and m s 6 2 2003 lefkada earthquakes the coseismic effects are presented in terms of time series displacement vectors differences of velocity vectors and changes of accumulated strain furthermore we compare the gps results with fault plane solutions and slip models of the corresponding earthquakes we found discontinuous changes of position of about 70 mm for the island of skyros which can be attributed to the 2001 skyros earthquake aegean sea a detailed displacement field was obtained for the 2003 lefkada earthquake ionian sea greece which induced coseismic southwestward displacements of up to 72 mm it is in agreement with the focal mechanism of the mainshock which caused a dextral strike slip of maximum 34 cm on a northeast striking plane the cumulative strain after the lefkada earthquake indicates an increased seismic hazard for the island of kefalonia ionian sea greece the 25 march 2007 kefalonia earthquake was located in this region

the minimum scale of grooving on faults at the field scale nearly all fault surfaces contain grooves generated as one side of the fault slips past the other grooves are so common that they are one of the key indicators of principal slip surfaces here we show that at sufficiently small scales grooves do not exist on fault surfaces a transition to isotropic roughness occurs at 4 500 mm although the scale of the transition can vary even between locales on a single fault the aspect ratio of the roughness at the transition is well defined for a given fault we interpret the transition between grooved and ungrooved scales as a transition in deformation mode of asperities on the slip surface grooves can form when a hard indenter slides past a softer surface at small scales the asperities appear to yield plastically and therefore do not generate grooves as hard indenters the plastic yielding can be a consequence of the high shear strains required to deform the surfaces at small scales where the aspect ratio roughness is high the transition to plastic yielding is predicted to occur at a specific aspect ratio for each fault as observed the new observation both shows a limit to one of the most commonly observed features of faults and suggests a change in the mode of failure of faults as a function of scale 2016 the authors

late glacial to holocene benthic foraminifera in the marmara sea implications for black sea mediterranean sea connections following the last deglaciation benthic foraminifera were studied from four gravity cores that penetrated holocene marine sediments in the marmara sea morphogroup and assemblage analyses reveal that the holocene sea level rise did not result in a catastrophic flooding event as proposed by w b f ryan and others whereby well oxygenated saline mediterranean waters rapidly inundated a low lying low salinity black sea lake at v7 15 ka popularly known as the noah s flood hypothesis rather the benthic foraminiferal data confirm the hypothesis that the dardanelles sill was breached by the mediterranean at v12 ka allowing saline waters to penetrate the marmara sea these saline waters reached the level of the bosphorus sill at v9 5 ka but were unable to penetrate into the black sea until after v9 1 ka because of the persistent strong outflow of brackish to fresh water from the black sea the initial colonisation of the marmara sea by benthic foraminifera is essentially synchronous with the re establishment of marine connections through the dardanelles strait at v12 ka by v10 ka ammonia dominated faunas developed on the strait exit delta v1 at the southern end of the bosphorus and at v9 1 ka the appearance of fully marine species documents the establishment of a more stratified water column over v1 finally the increase in abundance of planktonic foraminifera at the southern exit of the bosphorus after v6 1 ka reflects a decreased volume of outflow water from the black sea quantitative analysis of benthic foraminiferal morphogroups reveals that the oxygen content of subhalocline water was low below v1 5 ml l throughout the holocene and the occurrence of sapropel sediment in the deeper part of the basin suggests bottom waters may have been anoxic at times after v4 5 ka an increase in benthic foraminiferal oxic morphotypes suggests a reduction in black sea outflow and weakening of the halocline the strong and persistent stratification of the water column in the marmara sea throughout the holocene is entirely incompatible with the noah s flood hypothesis 2002 elsevier science b v all rights reserved

holocene palaeogeographies of the astakos coastal plain akarnania nw greece abstract this paper deals with holocene coastal changes of the astakos plain in akarnania nw greece palaeoenvironmental scenarios are based on the analysis of the lateral and vertical distribution patterns of sedimentary facies sediments from vibracorings were studied using geomorphological sedimentological microfaunal palaeobotanical and geochemical methods a geochronostratigraphy was achieved by 14c ams dating of organic matter we present palaeogeographical maps for different points in time since the mid holocene the evolution of the coastal area was generally controlled by the migration of a complex system of a shallow marine embayment an adjacent lagoonal environment and an adjoining coastal lake forced by the interaction of sea level rise tectonic movements and sediment supply from the hinterland the maximum transgression of the ionian sea took place at circa 5500 cal bc reaching approx 1 1 km inland the lagoon as well as the coastal lake had their largest dimensions around 4500 cal bc indicating a more humid climatic period in the course of a long lasting regression an asymmetric sedimentation pattern developed around 2500 cal bc it was characterized by strong fluvial deposition of the xeropotamos in the western plain and a small and narrow marine embayment with associated lagoonal to limnic coastal water bodies in the eastern plain the latter were related to karstic springs draining the adjacent rigani ridge around 500 cal bc the coastline lay about 200 m landward of its present position possible harbour sites for the ancient polis of astakos are a the area of modern astakos where a mole in a position seawards of the present coast would have guaranteed deep water conditions for anchoring or b the southeastern fringe of the plain where deep water prevailed and the nearby freshwater outlet protected the site from rapid siltation we found increased torrential activity i for the 6th 5th millennium bc ii for the 2nd half of the 1st millennium bc until roman times and iii at the end of the 19th century ad at least the two younger phases are mostly due to anthropogenic soil erosion between the 4th and the 2nd millennium bc a period of ecological stability existed relative changes in sea level for the bay of astakos were reconstructed for the first time since the mid holocene the relative sea level has never reached a higher position than today it rose from 12 50 m b s l at 6200 cal bc via 2 20 m b s l at 500 cal bc to its present level besides eustatic reasons tectonic subsidence due to the half graben structure of the area is the main trigger of the relative rise in sea level

holocene environmental and parasequence development of the st jones estuary delaware usa foraminiferal proxies of natural climatic and anthropogenic change abstract the benthic foraminiferal record of marshes located along western delaware bay st jones estuary usa reflects the response of estuaries to sea level and paleoclimate change during the holocene system tracts are recognized and within them parasequences based on sedimentological and foraminiferal assemblages identification the parasequences defined by foraminiferal assemblages appear correlative with rapid holocene climate changes that are of worldwide significance 6000 5000 4200 3800 3500 2500 1200 1000 and 600 cal years bp following postglacial sea level rise modern subestuaries and marshes in the region began to develop between 6000 and 4000 years bp depending on their proximity to the mouth of delaware bay and coastal geomorphology initial sediments were fluvial in origin with freshwater marshes established around 4000 years bp the subsequent sea level transgression occurred sufficiently slowly that freshwater marshes alternated with salt marshes at the same sites to around 3000 years bp locally another two transgressions are identified at 1800 and 1000 years bp respectively marine influence increased in the estuaries until 600 years bp little ice age when regression occurred sea level began to rise again during the mid 19th century at the end of the little ice age when marshes became established the presence of a sand lens in the upper and middle estuary and the reduction in the number of tests in the top samples in cores from the same area also suggest an anthropogenic influence the estuary infill resulted in a sharp transgressive sequence represented by salt marsh foraminiferal assemblages in the upper part of the cores the increase in marsh foraminifera in both areas suggests an increase in marine influence that might be due to the transgression beginning at the end of the little ice age about 150 180 years ago coupled with anthropogenic straightening of the channel in 1913

morphometric analysis and amino acid geochronology of uplifted shorelines in a tectonic region near reggio calambria south italy the tectonic coastline of the calabrian peninsula provides an opportunity to study the morphology and history of elevated marine shorelines near capo dell armi eleven shorelines are preserved between sea level and 256 m with some correlation difficulties posed by the dissection of the area by intermittent streams we are able to correlate several of the shorelines across the entire study area with the support of correlations provided by amino acid geochronology we have identified four shorelines dating from the last interglacial period isotope stage 5 the oldest two both contain the strombus bubonius fauna and are of indistinguishable early last interglacial ages stage 5e aminozone e ca 125 ka the highest terrace vii is associated with a shoreline at 157 m and the lower with a shoreline around 125 105 m a s l of the two younger stage 5 without strombus bubonius the higher v lies at about 90 100 m and produces amino acid ratios slightly younger than but statistically indistinguishable from those of aminozone e however the youngest last interglacial shoreline deposits iv have produced amino acid ratios correlated to late stage 5 5a elsewhere in the mediterranean basin amino acid and geomorphic data have shown that uplift varies the study area from 0 85 to 1 03 m ka and suggeststhat constant uplift along any one traverse is unlikely