on late miocene to recent vertical motions in the cretan segment of the hellenic arc abstract high resolution foraminiferal and calcareous nannoplankton biostratigraphy and reliable paleobathymetry estimates based on plankton benthos ratios in foraminifera make it possible to reconstruct in detail late neogene vertical motions along the central cretan segment of the hellenic arc these motions are considered to express the surficial effect of the roll back process of the hellenic subduction zone which started about 12 ma ago in contrast to earlier views there is no sustained uplift since the late middle miocene successive paleotopographic profiles for central crete show a predominance of subsidence coupled with an increase of differential reliefs from the latest serravallian until the messinian subsidence was most pronounced between the tortonian messinian boundary interval and the early part of the early pliocene locally up to a magnitude of more than 1000 m a two phased uplift history coupled with tilting to the north or northeast can be inferred from the late early pliocene recent record separated by a short early late pliocene episode of subsidence rates of uplift were highest in the early pliocene up to about 125 cm ka the central cretan late neogene to recent paleotopographic profiles are compared with those reconstructed from seismic interpretations and drilling data from the cretan sea the combined results show that paleotopographic configurations between the cyclades and crete were fairly similar to those on central crete until messinian time foundering of the cretan basin started in the course of the early pliocene but subsidence rates were less than the contemporaneous uplift rates of crete the timing and magnitude of the vertical motions along the cretan sea central cretan transect put detailed geological constraints on tectonophysical modelling of the surficial effects of the roll back process these vertical motions are discussed in view of the model of southward translation of a large supracrustal slab resulting in the origin of the cretan sea and in thrusting and uplift in the frontal parts of the slab where it thrusted over the northern limb of the subducted ionian plate

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

distinguishing potential sources of arsenic released to groundwater around a fault zone containing a mine site arsenic as contamination in groundwater in mineralized areas typically results from the oxidation of as rich sulfide minerals in aquifers from hydrothermal alteration of geothermal systems or as a result of anthropogenic influences such as mining activity the primary goal of this study was to determine the spatial and temporal variance in as concentrations in shallow groundwater in a mineralized area and to identify the main as source controlling the concentration patterns to this end a combination of a geostatistical technique for space time modeling of as concentrations and a numerical simulation which models the transport of as in groundwater is implemented a study site in north sulawesi sulawesi island indonesia was selected as it was suitable for investigating the importance of fault lines and metal mining on as contamination initially stable isotope analysis was used to ascertain the groundwater source and the mixing mechanism of the shallow and deep groundwater geostatistical modeling revealed consistent general patterns of as concentrations during the past 10 years with high concentrations found along a nw se axis by matching the geostatistical results with the distributions of as concentrations obtained through transport modeling the deep seated hydrothermal system along the fault zone was found to be the major as source wastewater from the mine was also observed to be a local as source another important influence on the as concentration pattern was a river which acted as a boundary to separate the groundwater systems into two regions

tracking earthquake archaeological evidence in late minoan iiib 1300 1200 b c crete greece a proof of concept late minoan lm iiib 1300 1200 b c represents a crucial period in the history of bronze age crete heralding the transition to the iron age through a wave of site destruction and abandonment according to the traditional view earthquakes may have played a significant role in these events a new archaeoseismological approach is proposed to test this hypothesis and to attribute destruction and abandonment to earthquakes potential earthquake archaeological effects peaes are defined and documented at lm iiib sites synchronisms of peaes between sites are based on ceramic evidence the reliability of the peaes is furthermore assessed using empirical ground motion relationships defined for three types of earthquake mechanisms that can be considered to occur in the seismotectonic context of crete 1 normal faulting earthquakes located within the overriding aegean lithosphere 2 earthquakes located on the subduction interface or on splay faults merging with the interface at depth 3 earthquakes within the subducting african lithosphere in the case of lm iiib1 early malia and sissi northeastern crete this proof of concept is successfully applied and supports the hypothesis that seismic shaking is likely to be responsible for the peaes observed a 12 october 1856 a d type earthquake located within the subducting african plate is suggested as the most likely earthquake mechanism in other lm iiib archaeological contexts no convincing evidence for earthquake effects could be identified the hypothesis of a seismic storm causing the demise of minoan crete is not supported by our analysis of archaeological evidence

mass wasting and uplift on crete and karpathos during the early pliocene related to initiation of south aegean left lateral strike slip tectonics reconstruction of the vertical motion history of crete and karpathos southeastern aegean region greece from the messinian to recent revealed a previously poorly documented late messinian phase of strong subsidence with rates of 50 100 cm k y followed by stasis during the fi rst 250 k y of the pliocene and then by uplift of 500 700 m during the late early to early middle pliocene uplift continued up to recent albeit at a slower pace and at different rates in different areas the lower pliocene in crete and karpathos is characterized by widespread occurrences of mass wasting deposits which were emplaced over a period of time spanning the fi rst 1 35 m y of the pliocene the origin of these masswasting deposits has long been enigmatic but is here related to uplift which started in crete as early as ca 5 ma it is suggested that the beginning uplift following strong subsidence of various fault blocks until late in the messinian is related to the onset of south aegean strike slip faulting we postulate that small scale tilting of fault blocks by transtensional strike slip faulting and increased seismic activity generated slope failures and subsequent sliding of poorly cemented lower pliocene and uppermost messinian lago mare sediments overlying the terminal miocene erosional unconformity the absence of mass wasting deposits after 3 98 ma while uplift continued is most likely the result of progressive compaction and cementation of the increasingly deeper buried lago mare and lower pliocene sediments thereby preventing slope failure to a depth of the terminal miocene unconformity hiatuses in some places in crete and on karpathos however indicate that slope failures continued to occur although on a smaller scale and less frequent than before connecting the change from subsidence to uplift in the earliest pliocene with the onset of left lateral strike slip tectonics in the southeastern aegean arc would make this major strike slip system much older by 2 m y than the generally accepted age of middle to late pliocene a recently postulated scenario of subduction transform edge propagator step faulting to explain the south aegean strike slip system predicts rates distribution and amount of uplift as rebound to southwestward retreat of the subducted slab along a transform fault zone that is in line with our fi ndings on crete and karpathos and explains the absence of compressional structures associated with the uplift as well as the ongoing southwestward motion of crete

fault slip rate variations during crustal scale strain localisation central italy rates of plate motion are generally uniform over 10 102 myrs timescales faults between tectonic plates might therefore be expected to show temporally uniform slip rates if the same number of faults remain active for an extending region of the eurasia africa plate boundary italy finite throw values vertical component of the slip for seismogenic normal faults are less than that predicted when recent throw rates are extrapolated over the fault lifetimes the effect correlates with distance from the fault system tips and demonstrates that the slip rates on centrally located faults have increased with time neighbouring normal faults were active in the quaternary but show no signs of surface faulting during the latest pleistocene to holocene death of these faults has provided the extra strain per unit time to drive the increased slip rates measured on other faults thus fault interaction and death modify slip rates and seismic hazards associated with plate tectonics

structural decoupling in a convergent forearc setting southern crete eastern mediterranean a multidisciplinary approach is used to investigate the structure of the southern cretan margin which is located in one of the most seismically active forearc regions in europe bathymetric seismic reflection and fault plane solution data were used to identify the main tectonic features on the margin correlating their evolution with the main sedimentary sequences recognized on crete in contrast to the majority of forearc settings in the pacific and indian oceans southern crete is a region of predominantly oblique movement above well defined detachment zones north dipping thrust faults identified on seismic reflection profiles reveal significant crustal shortening during the miocene due to the westward propagation of the hellenic fold and thrust system in addition east dipping thrust faults rooted on top of pre neogene strata were also identified but only a few of these thrusts affect neogene to holocene strata small scale domes derived from evaporitic messinian intrusions deform pliocene quaternary strata west and east dipping normal faults were also recognized within the mesozoic and cenozoic successions and these are related to regional extension during forearc convergence in such a setting the fault bounded continental slope of crete effectively separates a region of uplift crete from subsiding troughs to the south our work shows that structural segmentation at depth is complex with multiple crustal levels recording contrasting styles of deformation and distinct moment tensor solutions this complexity derives from the oblique style of convergence recorded south of crete which reactivates distinct crustal levels depending on their rheology and relative degree of metamorphism inherited during alpine compression as a result a strong correlation between seafloor morphology and transtensional movements is recorded in the upper 10 15 km of the crust while transpression prevailed after the serravallian below these depths

identifying groundwater arsenic contamination mechanisms in relation to arsenic concentrations in water and host rocks leaching and oxidation of high arsenic as host rocks tend to be induced by circulation of deep geothermal waters which increase as concentration in shallow groundwater the purpose of this study is to identify the mechanism of groundwater as contamination in relation to leaching and oxidation along the border between the south minahasa and bolaang mongondow districts north sulawesi indonesia this region contains miocene sedimentary rock hosted disseminated gold deposits associated with hydrothermal alteration in a fault zone abnormally high as concentrations were observed in hot and cold springs and in surrounding shallow groundwater for a total mineralization area of 8 10 km2 two methods were adopted in this study 1 microscopic and spectroscopic analyses of rock samples for mineral identification and 2 geostatistics for spatial modeling of as concentrations in groundwater jarosite was identified as the chief fill mineral in rock defects cracks and pores the presence of this mineral may indicate release of as into the environment as can occur as an alteration product derived from oxidation and leaching of pyrite as rich pyrite or sulfide minerals by geothermal waters moreover as concentrations in groundwater were estimated using geostatistics for spatial modeling the co kriging map identified local anomalies in groundwater as concentrations over the permissible limit 10 ppb such anomalies did not appear through ordinary kriging integration of the results indicates that as contamination in shallow groundwater probably is controlled by heterogeneous distributions of jarosite and variations in intensity and extent of hydrothermal activities

fault structure and deformation rates at the lastros sfaka graben crete abstract the lastros and sfaka faults have an antithetic relationship and form a ca 2 km wide graben within the ierapetra fault zone in eastern crete both faults have impressive bedrock fault scarps many metres in height which form prominent features within the landscape t lidar investigations undertaken on the lastros fault are used to accurately determine vertical displacements along a ca 1 3 km long scanned segment analyses show that previous estimations of post glacial slip rate are too high because there are many areas along strike where the scarp is exhumed by natural erosion and or anthropogenic activity in areas not affected by erosion there is mean scarp height of 9 4 m this leads to a slip rate of 0 69 0 15 mm a using 15 3 ka for scarp exhumation using empirical calculations the expected earthquake magnitudes and displacement per event are discussed based on our observations trenching investigations on the sfaka fault identify different generations of fissure fills retrodeformation analyses and 14c dating of the fill material indicate at least four events dating back to 16 055 215 cal bp with the last event having occurred soon after 6102 113 cal bp the lastros fault is likely the controlling fault in the graben and ruptures on the lastros fault will sympathetically affect the sfaka fault which merges with the lastros fault at a depth of 2 4 km the extracted dates from the sfaka fault fissure fills therefore either represent activity on the lastros fault assuming they formed coseismically or accommodation events cross sections show that the finite throw is limited to around 300 m and the derived slip rate for the lastros fault therefore indicates that both faults are relatively young having initiated 435 120 ka

fault zone connectivity slip rates on faults in the san francisco bay area california the slip rate of a fault segment is related to the length of the fault zone of which it is part in turn the slip rate of a fault zone is related to its connectivity with adjoining or contiguous fault zones the observed variation in slip rate on fault segments in the san francisco bay area in california is consistent with connectivity between the hayward calaveras and san andreas fault zones slip rates on the southern hayward fault taper northward from a maximum of more than 10 millimeters per year and are sensitive to the active length of the maacama fault

scaling properties of normal fault populations in the western corinth graben greece implications for fault growth in large strain settings abstract a variety of one dimensional and two dimensional map techniques of fractal analysis have been employed to investigate the scaling properties of the dominant wnw trending normal fault population of the western corinth graben in central greece to assess possible constraints on fault geometry during fault growth the data have been compiled separately from the northern and southern domains of the graben which have experienced differing amounts of finite strain based on power law distributions of the fault throw the applied extension is estimated at 30 and 22 for the northern and southern domains respectively however the fault spacing and fault length populations in both domains obey similar power law relationships these conclusions are also supported by maximum throw vs trace length data which demonstrate that the faults in the northern domain have systematically higher values for the slip to length ratios than those in the southern domain it is proposed that the corinth graben has reached fracture saturation that is the fault spacing stops evolving and displacement increases rather than faults lengthening to accommodate the increasing extension this growth process consistent with throw distributions along individual faults may be explained either in terms of a stress feedback mechanism or by the mechanical interaction between the wnw trending normal faults with a set of nne trending transverse faults

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

incremental growth of normal faults insights from a laser equipped analog experiment we conducted a laser equipped analog experiment aimed at quasi continuously monitoring the growth of a dense population of normal faults in homogeneous conditions to further understand the way geological faults progressively gain in slip and length as they accumulate more strain we measured with great precision the incremental slip and length changes that the analog faults sustain as they grow these measurements show that the analog faults share common features with the natural ones in particular during their growth the faults develop and maintain cumulative slip profiles that are generally triangular and asymmetric the growth takes place through two distinct phases an initial short period of rapid lateral lengthening followed by a longer phase of slip accumulation with little or no lengthening the incremental slip is found to be highly variable in both space along the faults and time resulting in variable slip rates in particular short and long term slip rates are markedly different we also find that slip measurements at local points on fault traces do not contain clear information on the slip increment repeat mode finally while the fault growth process is highly heterogeneous when considered at the scale of a few slip events it appears homogeneous and self similar at longer time scales which integrate many slip increments this is likely to be the result of a feedback between stress heterogeneities and slip development the long term scale homogeneity also implies that the long term faulting process is primarily insensitive to the short term heterogeneities that are rapidly smoothed or redistributed we propose a new conceptual scenario of fault growth that integrates the above observations and we suggest that faults grow in a bimodal way as a result of a self driven and self sustaining process

aegean tectonics strain localisation slab tearing and trench retreat abstract we review the geodynamic evolution of the aegean anatolia region and discuss strain localisation there over geological times from late eocene to present crustal deformation in the aegean backarc has localised progressively during slab retreat extension started with the formation of the rhodope metamorphic core complex eocene and migrated to the cyclades and the northern menderes massif oligocene and miocene accommodated by crustal scale detachments and a first series of core complexes mccs extension then localised in western turkey the corinth rift and the external hellenic arc after messinian times while the north anatolian fault penetrated the aegean sea through time the direction and style of extension have not changed significantly except in terms of localisation the contributions of progressive slab retreat and tearing basal drag extrusion tectonics and tectonic inheritance are discussed and we favour a model 1 where slab retreat is the main driving engine 2 successive slab tearing episodes are the main causes of this stepwise strain localisation and 3 the inherited heterogeneity of the crust is a major factor for localising detachments the continental crust has an inherited strong heterogeneity and crustal scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation the dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate successive slab ruptures from the middle miocene to the late miocene have isolated a narrow strip of lithosphere still attached to the african lithosphere below crete the formation of the north anatolian fault is partly a consequence of this evolution the extrusion of anatolia and the aegean extension are partly driven from below asthenospheric flow and from above extrusion of a lid of rigid crust

earthquake histories and holocene acceleration of fault displacement rates displacement rates for normal and reverse faults n 57 are generally higher when averaged for the holocene 10 ka than for the late quaternary 300 ka and longer time scales holocene acceleration of displacement rates could be attributed to geological processes that produce increases of tectonic tempo we propose an alternative model in which the observed rate changes arise from variability in earthquake slip and or recurrence coupled with a sampling bias toward those faults that are best represented at the earth s surface and that accrued displacement fastest during the holocene this model is consistent with displacement rates measured over time intervals of as long as 300 ka for 129 faults from the taupo rift new zealand departures of earthquake parameters and associated displacement rates from their long term 300 ka averages are attributed to fault interactions and occur on time intervals inversely related to these long term displacement rates and to regional strain rates

geo genic arsenic contamination in the kerman cenozoic magmatic arc kerman iran implications for the source identification and regional analysis kerman cenozoic magmatic arc kcma is located in the southeastern part of the central iranian volcano plutonic copper belt arsenic contamination from geo genic source is one of the most important environmental concerns in this area the main objective of this study was to determine the role of geothermal related activities in the arsenic contamination for this purpose the old and active geological indicators of the geothermal activities were investigated through the quaternary travertine deposits and the present hydrothermal warm springs respectively results showed that arsenic is highly concentrated ranged mainly from 12 400 to 90 500 mg kg in the reddish brown deposits of the travertine rocks arsenic showed geochemical association with co cu mo sb tl se fe and mn in these samples yukonite ca7fe3 12 aso4 10 oh 2015h2o a rare ca ferric arsenate hydrous mineral was the only as bearing mineral identified in the reddish brown deposits of the travertine rocks arsenic concentration in the hydrothermal warm springs 38 c ranged from 15 900 to 30 500 g l the dominant form was as h3aso30 hydrothermal contaminated waters also were characterized by na cl type and high values of ec 11 400 s cm tds 8300 mg l b 42 700 g l li 3000 g l fe 900 g l sb 82 8 g l and si 47 000 g l and natural anomalies of cs mn mo rb se and tl the obtained hydro geochemical results are similar to those reported in the literature for worldwide hydrothermal waters although natural attenuation processes such as adsorption co precipitation or mixing dilution reduce most of the arsenic contamination from hydrothermal source but some urban and rural communities are still depending on the arsenic contaminated waters with arsenic concentrations higher than recommended values for drinking or irrigation a subject that increases the risk of arsenic related diseases in some areas of the kerman province

earthquake synchrony and clustering on fucino faults central italy as revealed from in situ cl 36 exposure dating we recover the holocene earthquake history of seven seismogenic normal faults in the fucino system central italy we collected 800 samples from the well preserved limestone scarps of the faults and modeled their 36cl concentrations to derive their seismic exhumation history we found that 30 large earthquakes broke the faults in synchrony over the last 12 ka the seven faults released strain at the same periods of time 12 9 ka 5 3 ka and 1 5 1 ka on all faults the strain accumulation and release occurred in 3 6 ka supercycles each included a 3 5 ka phase of slow 0 5 2 mm yr strain accumulation in relative quiescence followed by a cluster of three to four large earthquakes or earthquake sequences that released most of the strain in 1 2 ka the large earthquakes repeated every 0 5 0 3 ka during the paroxysmal phases and every 4 3 0 9 ka between those phases earthquakes on the northern faults produced twice larger surface slips 2 m and had larger magnitudes mw 6 2 6 7 than those on the southern faults on most faults the relative strain level was found to control the amount of slip and the time of occurrence of the next large earthquake faults entered a phase of clustered activity once they had reached a specific relative strain threshold the tre monti fault is identified as the most prone to break over the next century our data document earthquake synchrony and clustering at a broader space and time scale than has been reported to date

geodetic evidence for low coupling on the hellenic subduction plate interface we develop a block model for the aegean and surrounding areas constrained by global positioning system gps in order to investigate the degree of coupling on the hellenic subduction interface i e the fraction of the motion across the plate boundary accommodated by elastic strain accumulation we use previously published models and seismicity to define the geometry of the interface separating the down going nubian slab from the overriding aegean this model provides a good fit to the gps observations for the 200 000 km2 aegean block the wrms of the residual velocities is 1 4 mm yr for 80 gps velocity estimates approximately the 95 level of the gps velocity uncertainties we investigate the degree of coupling on the seismically active plate interface the hellenic trench splay fault believed to be the source of the 365 ad great crete earthquake and tsunami and the kephalonia transform fault by comparing the modeled gps residual velocity field for a range of coupling values the gps observations are almost insensitive to coupling on the kephalonia transform fault because of the vertical dip of the fault that creates interseismic deformation only close to the fault where few gps sites exist the absence of resolvable shortening of the leading edge of the aegean plate precludes coupling of more than 0 2 20 of the full nubia aegean convergence rate on the modeled plate interface because of the shallow dip of the plate interface and trench splay fault and high rate of convergence if these boundaries were fully coupled high elastic strain rates would be expected to extend well into the overriding aegean plate based on our preferred value for the degree of coupling 0 1 and assuming characteristic earthquake behavior we estimate a recurrence time for great earthquakes with slip similar to that for the 365 crete event of 5700 8300 yr consistent with the absence of subsequent great earthquakes on this segment of the subduction zone

imaging spectroscopy earth and planetary remote sensing with the usgs tetracorder and expert systems 1 imaging spectroscopy is a tool that can be used to spectrally identify and spatially map materials based on their specific chemical bonds spectroscopic analysis requires significantly more sophistication than has been employed in conventional broadband remote sensing analysis we describe a new system that is effective at material identification and mapping a set of algorithms within an expert system decision making framework that we call tetracorder the expertise in the system has been derived from scientific knowledge of spectral identification the expert system rules are implemented in a decision tree where multiple algorithms are applied to spectral analysis additional expert rules and algorithms can be applied based on initial results and more decisions are made until spectral analysis is complete because certain spectral features are indicative of specific chemical bonds in materials the system can accurately identify and map those materials in this paper we describe the framework of the decision making process used for spectral identification describe specific spectral feature analysis algorithms and give examples of what analyses and types of maps are possible with imaging spectroscopy data we also present the expert system rules that describe which diagnostic spectral features are used in the decision making process for a set of spectra of minerals and other common materials we demonstrate the applications of tetracorder to identify and map surface minerals to detect sources of acid rock drainage and to map vegetation species ice melting snow water and water pollution all with one set of expert system rules mineral mapping can aid in geologic mapping and fault detection and can provide a better understanding of weathering mineralization hydrothermal alteration and other geologic processes environmental site assessment such as mapping source areas of acid mine drainage has resulted in the acceleration of site cleanup saving millions of dollars and years in cleanup time imaging spectroscopy data and tetracorder analysis can be used to study both terrestrial and planetary science problems imaging spectroscopy can be used to probe planetary systems including their atmospheres oceans and land surfaces

active simultaneous uplift and margin normal extension in a forearc high crete greece abstract the island of crete occupies a forearc high in the central hellenic subduction zone and is characterized by sustained exhumation surface uplift and extension the processes governing orogenesis and topographic development here remain poorly understood dramatic topographic relief 2 6 km astride the southern coastline of crete is associated with large margin parallel faults responsible for deep bathymetric depressions known as the hellenic troughs these structures have been interpreted as both active and inactive with either contractional strike slip or extensional movement histories distinguishing between these different structural styles and kinematic histories here allows us to explore more general models for improving our global understanding of the tectonic and geodynamic processes of syn convergent extension we present new observations from the south central coastline of crete that clarifies the role of these faults in the late cenozoic evolution of the central hellenic margin and the processes controlling quaternary surface uplift pleistocene marine terraces are used in conjunction with optically stimulated luminesce dating and correlation to the quaternary eustatic curve to document coastal uplift and identify active faults two south dipping normal faults are observed which extend offshore offset these marine terrace deposits and indicate active n s margin normal extension further marine terraces preserved in the footwall and hanging wall of both faults demonstrate that regional net uplift of crete is occurring despite active extension field mapping and geometric reconstructions of an active onshore normal fault reveal that the subaqueous range front fault of south central crete is synthetic to the south dipping normal faults on shore these findings are inconsistent with models of active horizontal shortening in the upper crust of the hellenic forearc rather they are consistent with topographic growth of the forearc in a viscous orogenic wedge where crustal thickening and uplift are a result of basal underplating of material that is accompanied by extension in the upper portions of the wedge within this framework a new conceptual model is presented for the late cenozoic vertical tectonics of the hellenic forearc

formation of late quaternary paleoshorelines in crete eastern mediterranean abstract paleoshorelines of late quaternary age in western crete do not exclusively increase in age with rising altitude as is generally observed worldwide at numerous sites for example late holocene paleoshorelines decrease in age with increasing altitude while in other cases paleoshorelines at similar altitude vary in age by tens of thousands of years we propose that the observed paleoshoreline altitude age relationships can be accounted for by eustatic sea level changes and tectonic rock uplift without requiring substantial errors on radiocarbon ages or tectonic subsidence as has been previously proposed to test this model we use a dataset consisting of altitude and age data for 71 individual paleoshorelines sampled from 21 sites distributed along the entire cretan coastline these data include radiocarbon ages of marine biota 40 new dates within beachrock resting on paleoshorelines ranging up to 48 kyr bp in age and 20 m above present sea level we find that paleoshoreline formation reflects late holocene tectonic rock uplift in western crete preceded by eustatic sea level rise and by 10 kyr bp rock uplift along the entire island our observations contravene existing models as they suggest that some paleoshorelines and their associated lithified beachrock survived passage through the wave zone multiple times and formed throughout the sea level cycle i e preservation is not restricted to highstand deposits these results may have application globally in regions where erosion resistant carbonate beachrock mantles paleoshorelines

fault slip accumulation in an active rift over thousands to millions of years and the importance of paleoearthquake sampling abstract the catastrophic earthquakes that recently september 4th 2010 and february 22nd 2011 hit christchurch new zealand show that active faults capable of generating large magnitude earthquakes can be hidden beneath the earth s surface in this article we combine near surface paleoseismic data with deep 1 ma timescales in the taranaki rift new zealand our analysis shows that the integration of different timescale datasets provides a basis for identifying active faults not observed at the ground surface estimating maximum fault rupture lengths inferring maximum short term displacement rates and improving earthquake hazard assessment we find that fault displacement rates become increasingly irregular both faster and slower on shorter timescales leading to incomplete sampling of the active fault population surface traces have been recognised for

tearing segmentation and backstepping of subduction in the aegean new insights from seismicity abstract this study revisits subduction processes at the hellenic subduction zone hsz including tearing segmentation and backstepping by refining the geometry of the nubian slab down to 150 180 km depth using well located hypocentres from global and local seismicity catalogues at the western termination of the hsz the kefalonia transform fault marks the transition between oceanic and continental lithosphere subducting to the south and to the north of it respectively a discontinuity is suggested to exist between the two slabs at shallow depths the kefalonia transform fault is interpreted as an active subduction transform edge propagator fault formed as consequence of faster trench retreat induced by the subduction of oceanic lithosphere to the south of it a model reconstructing the evolution of the subduction system in the area of peloponnese since 34 ma involving the backstepping of the subduction to the back side of adria provides seismological evidence that supports the single slab model for the hsz and suggests the correlation between the downdip limit of the seismicity to the amount of subducted oceanic lithosphere in the area of rhodes earthquake hypocentres indicate the presence of a nw dipping subducting slab that rules out the presence of a ne sw striking subduction transform edge propagator fault in the pliny strabo trenches region earthquake hypocentres also allow refining the slab tear beneath southwestern anatolia down to 150 180 km depth furthermore the distribution of microseismicity shows a first order slab segmentation in the region between crete and karpathos with a less steep and laterally wider slab segment to the west and a steeper and narrower slab segment to the east thermal models indicate the presence of a colder slab beneath the southeastern aegean that leads to deepening of the intermediate depth seismicity slab segmentation affects the upper plate deformation that is stronger above the eastern slab segment and the seismicity along the interplate seismogenic zone

seismicity of the hellenic subduction zone in the area of western and central crete observed by temporary local seismic networks temporary local seismic networks were installed in western crete in central crete and on the island gavdos south of western crete respectively in order to image shallow seismically active zones of the hellenic subduction zone more than 4000 events in the magnitude range between 0 5 and 4 8 were detected and localized the resulting three dimensional hypocenter distribution allows the localization of seismically active zones in the area of western and central crete from the mediterranean ridge to the cretan sea furthermore a three dimensional structural model of the studied region was compiled based on results of wide angle seismics surface wave analysis and receiver function studies the comparison of the hypocenter distribution and the structure has allowed intraplate and interplate seismicity to be distinguished high interplate seismicity along the interface between the subducting african lithosphere and the aegean lithosphere was found south of western crete where the interface is located at about 20 to 40 km depth an offset between the southern border of the aegean lithosphere and the southern border of active interplate seismicity is observed in the area of crete the offset varies laterally along the hellenic arc between about 50 and 70 km a southwards dipping zone of high seismicity within the aegean lithosphere is found south of central crete in the region of the ptolemy trench it reaches from the interface between the plates at about 30 km depth towards the surface in comparison the aegean lithosphere south of western crete is seismically much less active including the region of the ionian trench intraplate seismicity within the aegean plate beneath crete and north of crete is confined to the upper about 20 km between 20 and 40 km depth beneath crete the aegean lithosphere appears to be seismically inactive in western crete the southern and western borders of this aseismic zone correlate strongly with the coastline of crete

fault displacement rates on a range of timescales abstract displacements on tectonic faults primarily accrue during earthquakes at rates that vary through time to examine the processes that underlie the temporal changes in fault displacement rates we analyse displacements and displacement rates for time periods from the present to 5 10 20 300 500 1000 and 5000 kyr for 261 active reverse or normal faults from a worldwide dataset displacement rates depart from million year average rates by up to three orders of magnitude with the size of these departures inversely related to the duration of the sample period and to fault length short term 20 kyr displacement rates generally span a greater range on small faults than large a feature which suggests more variable growth on smaller faults simple earthquake slip modeling shows that variations in displacement rates require changes in both recurrence interval and slip per event and do not support the characteristic slip earthquake model as long as fault system strain rates are uniform displacement rates generally become constant over time periods between 20 and 300 kyr with the length of time required to reach stability being inversely related to the regional basin wide strain rates stable long term displacement rates and fluctuations in earthquake recurrence intervals and slip arise in part due to fault interactions

a new velocity field for greece implications for the kinematics and dynamics of the aegean 1 a new set of geodetic velocities for greece and the aegean derived from 254 survey mode and continuous gps sites is used to test kinematic and dynamic models for this area of rapid continental deformation modeling the kinematics of the aegean by the rotation of a small number 3 6 of blocks produces rms misfits of 5 mm yr 1 in the southern aegean and western peloponnese indicating significant internal strain within these postulated blocks it is possible to fit the observed velocities to within 2 3 mm yr 1 rms by models that contain 10 or more blocks but many such models can be found with widely varying arrangements of blocks that fit the data equally well provided that the horizontal dimension of those blocks is not larger than 100 200 km a continuous field of velocity calculated from the gps velocities by assuming that strain rates are homogeneous on the scale of 120 km fits the observed velocities to better than 2 3 mm yr 1 rms with systematic misfits representing more localized strain confined to a region approximately 100 100 km in size around the western gulf of corinth this velocity field accounts for the major active tectonic features of greece and the aegean including the widespread north south extensional deformation and the distributed strike slip deformation in the ne aegean and western greece the t axes of earthquakes are aligned with the principal axes of elongation in the geodetic field major active normal fault systems are perpendicular to those axes and 90 of the large earthquakes in this region during the past 120 years took place within the areas in which the geodetic strain rate exceeds 30 nanostrain yr 1 these observations suggest that the faulting within the upper crust of the aegean region is driven by forces that are coherent over a scale that is significantly greater than 100 km it is likely that those forces arise primarily from differences in gravitational potential energy within the lithosphere of the region

the tectonic development of the hellenic arc and the sea of crete a synthesis abstract we use field analyses together with interpretation of aerial photographs orbital imagery and sea beam data to define more accurately the geometry of fault systems in the hellenic arc the tectonics of the area are dominated by extensional processes related to normal faulting we then use sea beam data previous oceanographic studies and extrapolation of field analyses on surrounding islands to describe the fault pattern of the cretan sea basin which is found consistent with the land fault pattern the mechanisms of the late neogene and quaternary deformation of the central and southern aegean region are analysed in terms of stress trajectories as revealed by field studies of fault populations we then examine the subsidence of the sea of crete in terms of a model of uniform stretching of the lithosphere the opening of the sea of crete was cylindrical and did not result in bending of crete this leads us to modify the southern portion of an earlier kinematic reconstruction of aegea in agreement with recent paleomagnetic results the implications of the opening of the sea of crete on the tectonic evolution of the straits to the west and east of crete are discussed finally the uplift of the outer arc is explained by underplating due to subduction

the growth of geological structures by repeated earthquakes 2 field examples of continental dip slip faults a strong test of our understanding of the earthquake cycle is the ability to reproduce extant fault bounded geological structures such as basins and ranges which are built by repeated cycles of deformation along strike slip faults the coseismic and interseismic deformation can be nearly equal in magnitude and opposite in sign resulting in little permanent deformation except for the fault offset for dip slip faults portions of the crust are lifted and dropped and so buoyancy forces are exerted the seismic and interseismic deformations do not balance and structures grow and become subject to erosion and deposition we consider three examples for which the structure and fault geometry are well known the white wolf reverse fault in california site of the 1952 kern county m 7 3 earthquake the lost river normal fault in idaho site of the 1983 borah peak m 7 0 earthquake and the cricket mountain normal fault in utah site of quaternary slip events basin stratigraphy and seismic reflection records are used to profile the structure and coseismic deformation measured by leveling surveys is used to estimate the fault geometry to reproduce these structures we add the deformation associated with the earthquake cycle the coseismic slip and postseismic relaxation to the flexure caused by the observed sediment load treating the crust as a thin elastic plate overlying a fluid substrate the cumulative deformation is principally dependent on the elastic plate thickness modestly sensitive to the sediment substrate density difference and insensitive to the fluid viscosity for the 4 to 8 ma structures we deduce a longterm flexural rigidity of 2 15 1019 nm this is equivalent to an elastic plate thickness of 2 4 km for a young s modulus of 2 5 1010 nm 2 this value is found where independent estimates of the elastic thickness from the coherence between surface topography and gravity yield values of about 4 km but where coseismic fault slip extends to a depth of 10 15 km thus much of the seismogenic crust must weaken substantially during the life of active faults causing the fault bounded basins to narrow over time

a review of the source behaviour and distribution of arsenic in natural waters the range of as concentrations found in natural waters is large ranging from less than 0 5 g l 1 to more than 5000 g l 1 typical concentrations in freshwater are less than 10 g l 1 and frequently less than 1 g l 1 rarely much higher concentrations are found particularly in groundwater in such areas more than 10 of wells may be affected defined as those exceeding 50 g l 1 and in the worst cases this figure may exceed 90 well known high as groundwater areas have been found in argentina chile mexico china and hungary and more recently in west bengal india bangladesh and vietnam the scale of the problem in terms of population exposed to high as concentrations is greatest in the bengal basin with more than 40 million people drinking water containing excessive as these large scale natural as groundwater problem areas tend to be found in two types of environment firstly inland or closed basins in arid or semi arid areas and secondly strongly reducing aquifers often derived from alluvium both environments tend to contain geologically young sediments and to be in flat low lying areas where groundwater flow is sluggish historically these are poorly flushed aquifers and any as released from the sediments following burial has been able to accumulate in the groundwater arsenic rich groundwaters are also found in geothermal areas and on a more localised scale in areas of mining activity and where oxidation of sulphide minerals has occurred the as content of the aquifer materials in major problem aquifers does not appear to be exceptionally high being normally in the range 1 20 mg kg 1 there appear to be two distinct triggers that can lead to the release of as on a large scale the first is the development of high ph 8 5 conditions in semi arid or arid environments usually as a result of the combined effects of mineral weathering and high evaporation rates this ph change leads either to the desorption of adsorbed as especially as v species and a range of other anion forming elements v b f mo se and u from mineral oxides especially fe oxides or it prevents them from being adsorbed the second trigger is the development of strongly reducing conditions at near neutral ph values leading to the desorption of as from mineral oxides and to the reductive dissolution of fe and mn oxides also leading to as release iron ii and as iii are relatively abundant in these groundwaters and so4 concentrations are small typically 1 mg l 1 or less large concentrations of phosphate bicarbonate silicate and possibly organic matter can enhance the desorption of as because of competition for adsorption sites a characteristic feature of high groundwater as areas is the large degree of spatial variability in as concentrations in the groundwaters this means that it may be difficult or impossible to predict reliably the likely concentration of as in a particular well from the results of neighbouring wells and means that there is little alternative but to analyse each well arsenic affected aquifers are restricted to certain environments and appear to be the exception rather than the rule in most aquifers the majority of wells are likely to be unaffected even when for example they contain high concentrations of dissolved fe

interdependence of fault displacement rates and paleoearthquakes in an active rift paleoearthquakes at earth s surface often generate faults with variable displacement rates over short time intervals e g 18 k y the nature and origin of these variations and the extent to which they result from systematic and therefore predictable earthquake processes is unresolved we examine the processes underlying fluctuations in displacement rates by charting the accumulation of displacement over the last 60 k y on 25 normal fault traces distributed across the taupo rift new zealand displacement rates become more stable with increasing fault size and are uniform when aggregated across the entire rift the increased stability of fault displacement rates at greater spatial scales suggests that each fault is a component of a kinematically coherent system in which all faults interact and their earthquake histories are interdependent fault interdependencies generate short term complex 18 k y fluctuations in the timing and magnitude of earthquakes but also ultimately result in the stability of displacement rates on million year time scales

temporally constant quaternary uplift rates and their relationship with extensional upper plate faults in south crete greece constrained with 36cl cosmogenic exposure dating in order to investigate how active upper plate faults in crete influence uplift above the hellenic subduction zone we mapped deformed late quaternary marine terraces along 17 profiles across strike of the south central crete fault sccf identified and dated palaeoshorelines using in situ 36cl exposure dating on wave cut platforms correlated them with the quaternary sea level curve and calculated uplift rates we identified 16 distinct palaeoshorelines from field observations and study of digital elevation models dems located along the footwall and hangingwall of the sccf and the footwall of the offshore ptolemy trench fault cosmogenic dating constrains the ages of three palaeoshorelines as 76 100 and 125 ka we use these dates to guide a correlation of other mapped palaeoshorelines with quaternary sea level highstands between 200 and 980 ka with results implying that the uplift rate is constant through time at each of the 17 profile locations elastic half space modelling implies that uplift in both the hangingwall and footwall of the sccf is influenced by uplift related to offshore upper plate faults in addition to background regional uplift perhaps from the subduction interface by correlating palaeoshorelines across the active south central crete fault we derive a throw rate of 0 41 mm yr for this fault which can also be expressed as a slip rate of 0 58 mm yr the fault specific earthquake recurrence interval assuming repetition of 1 1 m slip events is approximately 2700 years for the sccf

variability of displacement at a point implications for earthquake size distribution and rupture hazard on faults abstract to investigate the nature of earthquake magnitude distributions on faults we compare the interevent variability of surface displacement at a point on a fault from a composite global data set of paleoseismic observations with the variability expected from two prevailing magnitude frequency distributions the truncated exponential model and the characteristic earthquake model we use forward modeling to predict the coefficient of variation cv for the alternative earthquake distributions incorporating factors that would effect observations of displacement at a site the characteristic earthquake model with a characteristic magnitude range of 0 25 produces cv values consistent with the data cv 0 5 only if the variability for a given earthquake magnitude is small this condition implies that rupture patterns on a fault are stable in keeping with the concept behind the model this constraint also bears upon fault rupture hazard analysis which for lack of point specific information has used global scaling relations to infer variability in average displacement for a given size earthquake exponential distributions of earthquakes from m 5 to the maximum magnitude give rise to cv values that are significantly larger than the empirical constraint a version of the model truncated at m 7 however yields values consistent with a larger cv 0 6 determined for small displacement sites although this result allows for a difference in the magnitude distribution of smaller surface rupturing earthquakes it may reflect in part less stability in the displacement profile of smaller ruptures and or the tails of larger ruptures online material global surface displacement data and identified sources of uncertainty

slip rate variations on normal faults during glacial interglacial changes in surface loads geologic and palaeoseismological data document a marked increase in the slip rates of the wasatch fault and three adjacent normal faults in the basin and range province during the late pleistocene early holocene epochs the cause of this synchronous acceleration of fault slip and the subsequent clustering of earthquakes during the holocene has remained enigmatic although it has been suggested that the coincidence between the acceleration of slip and the shrinkage of lake bonneville after the last glacial maximum may indicate a causal relationship here we use finite element models of a discrete normal fault within a rheologically layered lithosphere to evaluate the relative importance of two competing processes that affect fault slip postglacial unloading the removal of mass which decreases the slip rate and lithospheric rebound which promotes faster slip we show that lithospheric rebound caused by regression of lake bonneville and deglaciation of adjacent mountain ranges provides a feasible mechanism for the high holocene rates of faulting in the wasatch region our analysis implies that climate controlled changes in loads applied to earth s surface may exert a fundamental control on the slip history of individual normal faults

grouping and migration of surface faulting and variations in slip rates on faults in the great basin province abstract nonuniformity of the occurrence of large slip events producing surface ruptures on seismogenic faults and variations in slip rate probably characterize seismogenic faulting in the great basin province western united states examples include the grouping of faulting events along the lost river fault idaho changes in tilt rates of the east range and cortez mountains nevada extension of slip along a fault on the northwest flank of the humboldt range nevada and migration or shifting of slip back and forth from one fault to another along subparallel range front faults in dixie valley nevada

an uplift history of crete greece from inverse modeling of longitudinal river profiles we jointly invert cretan drainage networks to determine a temporal and spatial history of regional uplift our model assumes that longitudinal river profiles are controlled by uplift rate history and moderated by the erosional process we have parameterized fluvial erosion using an advective diffusive formulation the inverse model recovers the smoothest uplift rate history that best fits a data set of 250 longitudinal river profiles residual misfit between theoretical and observed river profiles decreases from 18 to 4 during optimization results suggest that crete has been uplifted by 1 2 km during the last 4 ma the central iraklion ridge first became emergent at 4 ma with eastern and western ends of crete emerging 1 ma later maximum uplift rates of 1 1 2 mm yr occurred in central and western crete between 0 and 1 ma this calculated history of uplift is consistent with independent sedimentological stratigraphic and paleontological constraints

earthquake mechanisms and active tectonics of the hellenic subduction zone summary we use improved focal mechanisms and centroid depth estimates of earthquakes combined with gps velocities to examine the tectonics of the hellenic subduction zone and in particular the processes occurring at both ends of the hellenic arc nubia aegean convergence is accommodated by shallowly dipping thrust faulting along the subduction zone interface as well as by steeper splay faults in the overriding material from a comparison of observed and expected seismic moment release over the last 100 yr combined with existing knowledge of the longer term documented historical record we confirm earlier suggestions that most 80 per cent of this convergence is accommodated aseismically that is that the subduction zone is uncoupled this conclusion is robust even allowing for rare very large earthquakes on splay faults such as that of ad 365 and also allowing for the contribution of small earthquakes the downgoing nubian plate deforms by arc parallel contraction at all depths from 200 km seaward of crete to at least 100 km within the subducting slab extensional t axes of earthquakes are aligned downdip within the descending slab suggesting that even if the aseismic prolongation of the slab has reached the 670 km mantle discontinuity it does not transmit stresses to shallower depths shallow thrust faulting earthquakes on the subduction interface show a divergence of slip vectors round the arc and gps measurements show that this is accommodated mainly by e w extension on normal faults in the overriding aegean material the eastern end of the subduction zone south of rhodes displays distributed deformation in the overriding material including a mixture of strike slip and splay thrust faulting and probably involves rotations about a vertical axes here slip on the interface itself is by thrust faulting with slip vectors oblique to the arc but parallel to the overall nubia aegean convergence there is no evidence for slip partitioning in the traditional sense in the west the subduction zone terminates in a distributed zone of parallel ne sw strike slip faults of which the most prominent is the kefalonia transform fault ktf a flexural gravity anomaly confirms that the deep bathymetric escarpment of the ktf is a lateral ramp formed as the ionian islands are emplaced sw onto the apulian lithosphere and enhanced by minor thrust faulting with slip vectors perpendicular to the scarp distributed parallel strike slip faults both sw and ne of mainland central greece terminate in e w graben in central greece which accommodate the overall ne sw shear by clockwise block rotation central greece therefore acts as a relay zone between the strike slip faulting of the ne aegean and the ionian islands western peloponnese

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

normal faulting in the forearc of the hellenic subduction margin paleoearthquake history and kinematics of the spili fault crete greece the late cenozoic kinematic and late pleistocene paleoearthquake history of the spili fault is examined using slip vector measurements and in situ cosmogenic cl 36 dating respectively the spili fault appears to have undergone at least three successive but distinct phases of extension since messinian similar to 7 ma with the most recent faulting resulting in the exhumation of its carbonate plane for a fault length of similar to 20 km earthquake slip and age data show that the lower 9 m of the spili fault plane were exhumed during the last similar to 16 500 years through a minimum of five large magnitude mw 6 earthquakes the timing between successive paleoearthquakes varied by more than one order of magnitude from 800 to 9000 years suggesting a highly variable earthquake recurrence interval during late pleistocene cv 1 this variability resulted to significant fluctuations in the displacement rate of the spili fault with the millennium rate 3 5 mm yr being about six times faster than its late pleistocene rate 0 6 mm yr the observed variability in the slip size of the paleoearthquakes is however significantly smaller cv 0 3 these data collectively suggest that the spili fault is one of the fastest moving faults in the forearc of the hellenic subduction margin c 2014 elsevier ltd all rights reserved

sea level change during the holocene in sardinia and in the northeastern adriatic central mediterranean sea from archaeological and geomorphological data abstract we provide new data on relative sea level change from the late holocene for two locations in the central mediterranean sardinia and ne adriatico they are based on precise measures of submerged archaeological and tide notch markers that are good indicators of past sea level elevation twelve submerged archaeological sites were studied six aged between 2 5 and 1 6 ka bp located along the sardinia coast and a further six dated 2 0 ka bp located along the ne adriatic coast italy slovenia and croatia for sardinia we also use beach rock and core data that can be related to holocene sea level the elevations of selected significant archaeological markers were measured with respect to the present sea level applying corrections for tide and atmospheric pressure values at the time of surveys the interpretation of the functional heights related to sea level at the time of their construction provides data on the relative changes between land and sea these data are compared with predictions derived from a new glacio hydro isostatic model associated with the last glacial cycle sardinia is tectonically relatively stable and we use the sea level data from this island to calibrate our models for eustatic and glacio hydro isostatic change the results are consistent with those from another tectonically stable site the versilia plain of italy the northeast adriatic italy slovenia and croatia is an area of subsidence and we use the calibrated model results to separate out the isostatic from the tectonic contributions this indicates that the adriatic coast from the gulf of trieste to the southern end of istria has tectonically subsided by 1 5 m since roman times

lithospheric structure of the aegean obtained from p and s receiver functions combined p and s receiver functions from seismograms of teleseismic events recorded at 65 temporary and permanent stations in the aegean region are used to map the geometry of the subducted african and the overriding aegean plates we image the moho of the subducting african plate at depths ranging from 40 km beneath southern crete and the western peloponnesus to 160 km beneath the volcanic arc and 220 km beneath northern greece however the dip of the moho of the subducting african plate is shallower beneath the peloponnesus than beneath crete and rhodes and flattens out beneath the northern aegean observed p to s conversions at stations located in the forearc indicate a reversed velocity contrast at the moho boundary of the aegean plate whereas this boundary is observed as a normal velocity contrast by the s to p conversions our modeling suggests that the presence of a large amount of serpentinite more than 30 in the forearc mantle wedge which generally occurs in the subduction zones may be the reason for the reverse sign of the p to s conversion coefficient moho depths for the aegean plate show that the southern part of the aegean crustal thickness of 20 22 km has been strongly influenced by extension while the northern aegean sea which at present undergoes the highest crustal deformation shows a relatively thicker crust 25 28 km this may imply a recent initiation of the present kinematics in the aegean western greece crustal thickness of 32 40 km is unaffected by the recent extension but underwent crustal thickening during the hellenides mountains building event the depths of the aegean moho beneath the margin of the peloponnesus and crete 25 28 and 25 33 km respectively show that these areas are also likely to be affected by the aegean extension even though the cyclades crustal thickness of 26 30 km were not significantly involved in this episode the aegean lithosphere asthenosphere boundary lab mapped with s receiver functions is about 150 km deep beneath mainland greece whereas the lab of the subducted african plate dips from 100 km beneath crete and the southern aegean sea to about 225 km under the volcanic arc this implies a thickness of 60 65 km for the subducted african lithosphere suggesting that the aegean lithosphere was not significantly affected by the extensional process associated with the exhumation of metamorphic core complexes in the cyclades

displacement history of a limestone normal fault scarp northern israel from cosmogenic 36cl the abundance of cosmogenic 36 cl measured in 41 limestone samples from a 9 m high bedrock fault scarp allows us to construct the 14 kyr fault displacement history of the nahef east normal fault northern israel 300 m above sea level n33 latitude the nahef east fault is one of a series of fault scarps located along the 700 m high zurim escarpment a major geomorphic feature samples at the top of the scarp have the highest nuclide concentrations 79 x 10 4 atoms g rock 1 samples at the base have the lowest 11 x 10 4 atoms g rock 1 using chemical data from the samples nahef east fault scarp geometry and surface and subsurface production rates for the 36 cl producing reactions we have constructed a numerical model that calculates 36 cl accumulation on a scarp through time given a series of unique displacement scenarios the resulting model 36 cl concentrations are compared to those measured in the scarp samples faulting histories that result in a good match between measured and modeled 36 cl abundances show three distinct periods of fault activity during the past 14 kyr with over 6 vertical meters of motion occurring during a 3 kyr time period in the middle holocene smaller amounts of displacement occurred before and after the period of most rapid motion the episodic behavior of the nahef east fault indicates that the average displacement rate of this fault system has varied through time

comparative planetary mineralogy implications of martian and terrestrial jarosite a crystal chemical perspective abstract the importance of the discovery of jarosite at the meridiani planum region of mars is discussed terrestrial studies demonstrate that jarosite requires a unique environment for its formation crystallizing from highly acidic ph 2 that reacted with aqueous solutions in shallow aquifers or on the martian surface this interaction forms both h 2 so 4 and h 2 s a martian oxidant must be identified to both oxidize h 2 s to produce the required acidity of the fluid and to oxidize fe 2 to fe 3 we suggest that reactions involving both sulfur and the reduction of co 2 to co may provide part of the answer the jarosite crystal structure is truly remarkable in terms of its tolerance for the substitution of a large number of different cations with different ionic radii and charges the structure accommodates hydrogen oxygen and sulfur the stable isotope systematics of which are strong recorders of low temperature fluid rock atmosphere interactions jarosite has been proven to be a robust chronometer for ar ar and k ar dating techniques and there is every reason to believe that u pb rb sr and nd sm techniques for older jarosite from mars will also be robust although the discovery of jarosite on mars alone with no other analytical measurements on the phase has given us insights to martian surficial processes the true power of jarosite can not be exploited until jarosite is sampled and returned from mars mars sample return is a long way off but until then we should be vigilant about examining martian meteorites for alteration assemblages that contain jarosite a suite of jarosite samples representing a significant time span on mars may hold the key to reading the record of martian atmospheric evolution

a more precise chronology of earthquakes produced by the san andreas fault in southern california improved methods of radiocarbon analysis have enabled us to date more precisely the earthquake ruptures of the san andreas fault that are recorded in the sediments at pallett creek previous dates of these events had 95 confidence errors of 50 100 calendar years new error limits are less than 23 calendar years for all but two of the dated events this greater precision is due to larger sample size longer counting time lower background noise levels more precise conversion of radiocarbon ages to calendric dates and better stratigraphic constraints and statistical techniques the new date ranges with one exception fall within the broader ranges estimated previously but our estimate of the average interval between the latest 10 episodes of faulting is now about 132 years variability about the mean interval is much greater than was suspected previously five of the nine intervals are shorter than a century three of the remaining four intervals are about two to three centuries long despite the wide range of these intervals a pattern in the occurrence of large earthquakes at pallett creek is apparent in the new data the past 10 earthquakes occur in four clusters each of which consists of two or three events earthquakes within the clusters are separated by periods of several decades but the clusters are separated by dormant periods of two to three centuries this pattern may reflect important mechanical aspects of the fault s behavior if this pattern continues into the future the current period of dormancy will probably be greater than two centuries this would mean that the section of the fault represented by the pallett creek site is currently in the middle of one of its longer periods of repose between clusters and sections of the fault farther to the southeast are much more likely to produce the next great earthquake in california the greater precision of dates now available for large earthquakes recorded at the pallett creek site enables speculative correlation of events between paleoseismic sites along the southern half of the san andreas fault a history of great earthquakes with overlapping rupture zones along the mojave section of the fault remains one of the more attractive possibilities

geodetic constraints on the tectonic evolution of the aegean region and strain accumulation along the hellenic subduction zone article i nfo we present evidence that gps velocity estimates of plate motions and fault slip rates agree to within uncertainties with geologic estimates during the most recent phase of the geologic evolution of the e mediterranean region post late miocene on this basis we use the gps differential velocities to estimate the timing of initiation of the principal structures in nw turkey the n aegean sea and central greece including the marmara sea the gulfs of evia goe and corinth goc and the kephalonia transform fault ktf we interpret these ages to indicate that the north anatolian fault propagated across the n aegean opening the goe and goc and initiating the ktf during the past 1 4 ma we further suggest that aegean extension that was earlier more distributed across the aegean basin became focused on this new fault system allowing the southern aegean and peloponnisos to translate sw with little internal deformation as observed today with gps this change in tectonic configuration may account for the clear geologic evidence for crustal thinning throughout the s aegean in apparent contradiction with low present day strain rates we further show that the low present day strain rate along the southern edge of the aegean micro plate requires substantial aseismic slip along the plate interface below crete consistent with the low level of historic subduction type earthquakes along this segment of the subduction zone

surface rupture of multiple crustal faults in the 2016 mw 7 8 kaikōura new zealand earthquake multiple 20 20 crustal faults ruptured to the ground surface and seafloor in the 14 november 2016 m w mw 7 8 kaik ura earthquake and many have been documented in detail providing an opportunity to understand the factors controlling multifault ruptures including the role of the subduction interface we present a summary of the surface ruptures as well as previous knowledge including paleoseismic data and use these data and a 3d geological model to calculate cumulative geological moment magnitudes m g w mwg and seismic moments for comparison with those from geophysical datasets the earthquake ruptured faults with a wide range of orientations sense of movement slip rates and recurrence intervals and crossed a tectonic domain boundary the hope fault the maximum net surface displacement was 12 m 12 m on the kekerengu and the papatea faults and average displacements for the major faults were 0 7 1 5 m south of the hope fault and 5 5 6 4 m to the north m g w mwg using two different methods are m g w mwg 7 7 0 3 0 2 7 7 0 2 0 3 and the seismic moment is 33 67 of geophysical datasets however these are minimum values and a best estimate m g w mwg incorporating probable larger slip at depth a 20 km seismogenic depth and likely listric geometry is m g w mwg 7 8 0 2 7 8 0 2 suggests 32 32 of the moment may be attributed to slip on the subduction interface and or a midcrustal detachment likely factors contributing to multifault rupture in the kaik ura earthquake include 1 the presence of the subduction interface 2 physical linkages between faults 3 rupture of geologically immature faults in the south and 4 inherited geological structure the estimated recurrence interval for the kaik ura earthquake is 5 000 10 000 yrs 5 000 10 000 yrs and so it is a relatively rare event nevertheless these findings support the need for continued advances in seismic hazard modeling to ensure that they incorporate multifault ruptures that cross tectonic domain boundaries

long term earthquake clustering a 50 000 year paleoseismic record in the dead sea graben the temporal distribution of earthquakes in the dead sea graben is studied through a 50 000 year paleoseismic record recovered in laminated sediments of the late pleistocene lake lisan paleo dead sea the lisan represents more than 10 times the 4000 years of historical earthquake records it is the longest and most complete paleoseismic record along the dead sea transform and possibly the longest continuous record on earth it includes unique exposures of seismite beds earthquake induced structures associated with slip events on syndepositional faults the seismites are layers consisting of mixtures of fragmented and pulverized laminae the places where the seismites abut syndepositional faults are interpreted as evidence for their formation at the sediment water interface during slip events on these faults thicker sediment accumulation above the seismites in the downthrown blocks indicates that a seismite formed at the water sediment interface on both sides of the fault scarps modern analogs and the association with surface ruptures suggest that each seismite formed during a m l 5 5 earthquake the 230 th 234 u ages of a columnar section obtained by thermal ionization mass spectrometry give a mean recurrence time of 1600 years of m l 5 5 earthquakes in the dead sea graben the earthquakes cluster in 10 000 year periods separated by quiet periods of similar length this distribution implies that a long term behavior of the dead sea transform should be represented by a mean recurrence of at least 20 000 year record this observation has ramifications for seismic hazard assessment based on shorter records

generic along strike segmentation of afar normal faults east africa implications on fault growth and stress heterogeneity on seismogenic fault planes understanding how natural faults are segmented along their length can provide useful insights into fault growth processes stress distribution on fault planes and earthquake dynamics we use cumulative displacement profiles to analyze the two largest scales of segmentation of 900 normal faults in afar east africa we build upon a prior study by manighetti et al 2009 and develop a new signal processing method aimed at recovering the number position displacement and length of both the major i e longest and the subordinate secondary segments within the faults regardless of their length age geographic location total displacement and slip rate 90 of the faults contain two to five major segments whereas more than 70 of these major segments are divided into two to four secondary segments in each hierarchical rank of fault segmentation most segments have a similar proportional length whereas the number of segments slightly decreases with fault structural maturity the along strike segmentation of the afar faults is thus generic at its two largest scales we summarize published fault segment data on 42 normal reverse and strike slip faults worldwide and find a similar number two to five of major and secondary segments across the population we suggest a fault growth scenario that might account for the generic large scale segmentation of faults the observation of a generic segmentation suggests that seismogenic fault planes are punctuated with a deterministic number of large stress concentrations which are likely to control the initiation arrest and hence extent and magnitude of earthquake ruptures

new injection experiments in non newtonian fluids in order to identify the dominant non newtonian effects which occur during the injection of a new newtonian magma through a partially crystallized magma chamber we have performed some preliminary analogue experiments which enable us to point out several features induced by the non newtonian properties of the host fluid during injection processes these experiments were performed in a three dimensional device and involve complex non newtonian fluids clay suspensions in which rheological properties such as bulk strength yield strength and rheofluidification exponent may vary forced injection takes place through a slot which in the case of a newtonian host fluid is the geometry that provides planar structures depending both on the density contrast and on the rheological contrast between the injected dyed water and the host fluid three kind of structures were observed 1 permanent plumes when the injected water is lighter than the suspension exhibiting rheological properties close to newtonian fluids 2 pseudo fountains and spreading at the bottom of the tank with a destabilizing density contrast and in high yield strength more viscous suspensions 3 fountains with a slightly stablizing density contrast the implications for magma chamber evolution are briefly discussed in particular it seems that homogeneous non newtonian media inhibit the formation of planar structures and partially crystallized magma may induce the spreading of the new magma at the bottom or at the top of the chamber regardless of the density contrast between the magmas

the growth and propagation of synsedimentary faults abstract offset of each syn fault horizon across a synsedimentary i e growth fault records the throw subsequent to its deposition allowing successive growth stages of a fault to be determined this technique has been applied to synsedimentary faults mapped on 3d seismic datasets to distinguish between faults which propagated laterally during growth faults which did not propagate laterally for significant growth periods and faults in which the lateral dimensions of the active surface decreased during their growth these different fault tip line behaviours result in characteristic lateral and dip parallel fault displacement variations fault propagation rates have been measured for 10 fault tips the maximum propagation rate is 15 km my for gravity driven faults and 3 km my for tectonically driven faults rates of fault propagation decrease with elapsed time from the initiation of faulting with tip line stasis and retreat becoming dominant in the later stages of fault growth static and retreating lateral tip lines are associated with overlap of the fault strain field with that of a neighbouring fault most often with the formation of a fault relay zone

breaking a subduction termination from top to bottom the large 2016 kaikōura earthquake new zealand abstract subduction systems globally terminate allowing plate motion to be transferred from the oceanic megathrust onto continental and or oceanic transform faults the mechanism of this kinematic transition over earthquake timescales is however poorly understood due to a lack of relevant data here we study the 2016 mw 7 8 kaik ura earthquake in new zealand the first large instrumentally recorded earthquake across a subduction termination to investigate this transfer mechanism in detail we find that the kaik ura earthquake unlike standard subduction earthquakes globally involved a predominance 80 of coseismic slip on upper plate faults and minor triggered slip on the underlying oceanic subduction thrust in the months following the earthquake the subduction thrust accommodated most of the earthquake s afterslip down dip of its co seismic rupture zone this top down strain release mechanism is in accord with local geological geodetic and historical seismicity data which suggest that the bulk of plate convergence 75 is accommodated in the upper plate we suggest therefore that this alternative strain release mechanism which is distinct from standard plate boundary earthquakes is characteristic of subduction terminations and results in the majority of seismic tsunami hazard being on steep near surface faults

geologic context of geodetic data across a basin and range normal fault crescent valley nevada geodetic strain and late quaternary faulting in the basin and range province is distributed over a region much wider than historic seismicity which is localized near the margins of the province in the relatively aseismic interior both the magnitude and direction of geodetic strain may be inconsistent with the holocene faulting record we document the best example of such a disagreement across the ne striking 55 nw dipping crescent normal fault where a nw oriented 70 km geodetic baseline records contemporary shortening of 2 mm yr orthogonal to the fault trace in contrast our geomorphic paleoseismic and geochronologic analyses of the crescent fault suggest that a large extensional rupture occurred during the late holocene epoch an excavation across the fault at fourmile canyon reveals that the most recent event occurred at 2 8 0 1 ka with net vertical tectonic displacement of 4 6 0 4 m at this location corresponding to the release of 3 m of accumulated nw se extension measured alluvial scarp profiles suggest a minimum rupture length of 30 km along the range front for the event implying a moment magnitude m w of at least 6 6 no prior event occurred between 2 8 ka and 6 4 0 1 ka the 14 c calender age of strata near the base of the exposed section assuming typical slip rates for basin and range faults 0 3 mm yr these results imply that up to one third or 1 m of the extensional strain released in the previous earthquake could have reaccumulated across the fault since 2 8 ka however the contemporary shortening implies that the fault is unloading due to a transient process whose duration is limited to between 6 years geodetic recording time and 2 8 ka the age of the most recent event these results emphasize the importance of providing accurate geologic data on the timescale of the earthquake cycle in order to evaluate geodetic measurements

multiseismic cycle deformation rates from holocene normal fault scarps on crete greece morphotectonic features reveal recent seismic activity on normal faults on crete allowing slip rates palaeoearthquake magnitudes and earthquake recurrence intervals to be inferred the studied faults show major escarpments 100s m high 10s km long separating uplifted mesozoic rocks from quaternary deposits during the holocene slip rates outpaced erosion sedimentation rates and 5 15 m high fresh scarps formed at the base of the major escarpments based on our field observations and following empirical relationships between magnitude surface rupture length and maximum co seismic vertical displacement it is possible to infer some important seismotectonic parameter relative to the investigated faults taking into account the possible sources of error and the corresponding uncertainties our preferred long term slip rates range between 0 5 and 1 3 mm yr 1 the maximum expected magnitudes between 6 3 and 6 6 or 6 5 and 6 8 considering worst case scenarios while the mean recurrence intervals range between 260 and c 840 years these estimates are in good agreement with the shallow seismicity thus allowing to improve our knowledge on the seismic potential in crete horizontal extension rates could be also inferred from our geological data and compared with the few available gps data

slip along the san andreas fault associated with the great 1857 earthquake historical records indicate that several meters of lateral slip along the san andreas fault accompanied the great 1857 earthquake in central and southern california these records together with dendrochronological evidence suggest that the rupture occurred along 360 to 400 km of the fault including several tens of kilometers of the currently creeping reach in central california geomorphic expressions of late holocene right lateral offsets are abundant along the 1857 rupture along 300 kilometers of the 1857 rupture between cholame and wrightwood the youngest discernible offset ranges from 3 to 9 1 2 meters dormancy of the fault since 1857 almost certainly indicates that this latest offset was created in 1857 fault slip apparently associated with the 1857 earthquake varies in a broadly systematic way along the trace of the fault it is relatively uniform along each of several long segments but changes rather abruptly in value between these segments this nonuniform displacement pattern may imply that some segments of the fault rupture more frequently or experience a slower long term slip rate than others the 1857 offsets indicate a seismic moment m o between 5 3 and 8 7 10 27 dyne cm assuming a 10 to 15 km depth of rupture and relatively uniform slip as a function of depth a comparison with the rupture length average slip value and tectonic setting of the california earthquake of 1906 m s 8 1 4 indicates a value of m 8 1 4 for the 1857 event

active faulting on the island of crete greece in order to characterize and quantify the middle late quaternary and ongoing deformation within the southern aegean forearc we analyse the major tectonic structures affecting the island of crete and its offshore the normal faults typically consist of 4 30 km long dipslip segments locally organised in more complex fault zones they separate carbonate and or metamorphic massifs in the footwall block from loose to poorly consolidated alluvial and colluvial materials within the hangingwall all these faults show clear evidences of recent re activations and trend parallel to two principal directions wnw ese and nne ssw based on all available data for both onland and offshore structures morphological and structural mapping satellite imagery and airphotographs remote sensing as well as the analysis of seismic profiles and the investigation of marine terraces and holocene raised notches along the island coasts for each fault we estimate and constrain some of the principal seismotectonic parameters and particularly the fault kinematics the cumulative amount of slip and the slip rate following simple assumptions and empirical relationships maximum expected magnitudes and mean recurrence periods are also suggested summing up the contribution to crustal extension provided by the two major fault sets we calculate both arc normal and arcparallel long term strain rates the occurrence of slightly deeper and more external low angle thrust planes associated with the incipient continental collision occurring in western crete is also analysed although these contractional structures can generate stronger seismic events m 7 5 they are probably much rarer and thus providing a minor contribution to the overall morphotectonic evolution of the island and the forearc a comparison of our geologicallybased results with those obtained from gps measurements show a good agreement therefore suggesting that the present day crustal deformation is probably active since middle quaternary and mainly related to the seismic activity of upper crustal normal faults characterized by frequent shallow 20 km moderate to strong seismic events seldom alternating with stronger earthquakes occurring along blind low angle thrust planes probably ramping from a deeper aseismic detachment ca 25 km this apparently contradicting co existence of juxtaposed upper tensional and lower compressional tectonic regimes is in agreement with the geodynamics of the region characterised by continental collision with nubia and the aegean mantle wedging

map view restoration of aegean west anatolian accretion and extension since the eocene 1 the aegean region greece western turkey is one of the best studied continental extensional provinces here we provide the first detailed kinematic restoration of the aegean region since 35 ma the region consists of stacked upper crustal slices nappes that reflect a complex paleogeography these were decoupled from the subducting african adriatic lithospheric slab especially since 25 ma extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes we reconstruct up to 400 km of trench perpendicular ne sw extension in two stages from 25 to 15 ma the aegean forearc rotated clockwise relative to the moesian platform around euler poles in northern greece accommodated by extensional detachments in the north and an inferred transfer fault se of the menderes massif the majority of extension occurred after 15 ma up to 290 km by opposite rotations of the western and eastern parts of the region simultaneously the aegean region underwent up to 650 km of post 25 ma trench parallel extension leading to dramatic crustal thinning on crete we restore a detachment configuration with the mid cycladic lineament representing a detachment that accommodated trench parallel extension in the central aegean region finally we demonstrate that the sakarya zone and cretaceous ophiolites of turkey cannot be traced far into the aegean region and are likely bounded by a pre 35 ma n s fault zone this fault became reactivated since 25 ma as an extensional detachment located west of lesbos island the paleogeographic units south of the izmir ankara sava suture however can be correlated from greece to turkey

scaling systematics of fault sizes on a large scale range fault map abstract a large scale high quality fault map was produced for an intensively mined area of the u k south yorkshire coalfield this database has been used to investigate both the scaling properties of fault systems and the robustness of techniques for the prediction of sub resolution faulting the mapped area is 87 km 2 and contains 2257 individual fault traces with on average one throw reading available for every 82 m of fault trace recorded throw values range from 10 cm to 180 m and fault trace lengths from 10 m to 12 km two sets of normal faults nw and ne striking are present together with local wnw striking dextral strike slip zones size populations are power law over at least 2 5 orders of magnitude and the exponents of the throw maximum throw and fault trace length population curves are interrelated and taking into account the effects of resolution on trace length populations are internally consistent derivatives of the primary map reproduce resolutions typical of offshore seismics and illustrate the limitations of seismic data power law fault size distributions provide a basis for sub seismic fault prediction for this data set a fault throw resolution of better than 10 m would be required to provide an accurate prediction of the throw population down to ca 0 6m

motion on the kaparelli fault greece prior to the 1981 earthquake sequence determined from 36cl cosmogenic dating in february and march 1981 three successive destructive earthquakes occurred at the eastern end of the gulf of corinth the third shock march 4 ms 6 4 ruptured the kaparelli fault about 40 cm of a limestone fault scarp was exhumed by the earthquake each major prehistoric earthquake has added new surface to this cumulative scarp exposing fresh material to cosmic ray bombardment using 36cl cosmic ray exposure dating we have obtained the continuous exposure history for this 4 5 m high limestone surface at two sites about 50 m apart the results suggest that the kaparelli fault has ruptured three times prior to 1981 at 20 3 ka 14 5 0 5 ka and 10 5 0 5 ka with slip amplitudes between 0 6 m and 2 1 m the kaparelli fault appears to have been inactive for 10 thousand years prior to the 1981 event

uplift rate transients at subduction margins due to earthquake clustering coastal uplift is common in continental fore arc systems with elevated paleoshorelines indicating that uplift rates can vary dramatically over time on individual margins the origins of these changes in uplift rates are examined using a global data set of paleoshorelines together with 2 d numerical models of subduction systems empirical paleoshoreline data n 282 from eight subduction margins indicate that uplift rates are generally not steady state and varied by up to a factor of 20 during the late quaternary 125 ka on many subduction margins uplift rates increase to the present day a finding which we attribute to sampling bias toward those locations where holocene uplift rates have been highest with respect to other global margins which have undergone fast subsidence or no vertical motion e g a property akin to the so called sadler effect paleoshorelines and 2 d models suggest that transient uplift rates at subduction margins are mainly a short term 20 ka phenomenon that cannot be accounted for by plate boundary scale processes such as changes in the rates of plate convergence sediment underplating or isostatic unloading instead time variable uplift rates are ascribed to temporal clustering of large magnitude earthquakes on upper plate faults and to a lesser extent the subduction thrust the potential for future damaging earthquakes and tsunamis may have been underestimated at active subduction margins with no measureable holocene uplift and in such cases late quaternary paleoshorelines could provide an important constraint for hazard analysis

arsenic contamination in surface drainage and groundwater in part of the southeast asian tin belt nakhon si thammarat province southern thailand the occurrence of human health problems resulting from arsenic contamination of domestic water supplies in ron phibun district nakhon si thammarat province southern thailand was first recognized in 1987 the area has an extensive history of bedrock and alluvial mining the waste from which is typically rich in arsenopyrite and related alteration products in 1994 a collaborative study was instigated involving thai and british government authorities to establish the distribution and geochemical form of as in surface drainage and aquifer systems in the affected area the probable sources of as contamination and the potential for problem alleviation hydrochemical analyses of surface and groundwaters have confirmed the presence of dissolved as at concentrations exceeding who potable water guidelines by up to a factor of 500 contamination of the shallow alluvial aquifer system is systematically more severe than the underlying carbonate hosted aquifer deep boreholes may therefore provide the best available potable water source for the local population the presence of up to 39 of total as as arsenite h3aso3 within the carbonate aquifer may however constitute a hidden toxicological risk not evident in the shallow groundwater in which arsenate species account for 95 of total as mineralogical investigations of as rich tailings and flotation wastes were undertaken to evaluate their likely impact on water quality the results indicate that although some flotation wastes contain up to 30 as the rate of leaching is extremely low consequently the as loading of drainage emanating from such waste is below the subregional average analyses of the silty alluvium that covers much of the central sector of the study area have highlighted as concentrations of up to 5000 mg kg 1 probably carried by disseminated arsenopyrite following sulfide dissolution the mobility of as in this material may be high with resultant contamination of shallow groundwater due to the low fe content of the soil on the basis of the data acquired a range of pollution mitigation schemes are currently under investigation including fe supplementation of alluvium and microbial degradation of disseminated arsenopyrite

sour gas hydrothermal jarosite ancient to modern acid sulfate mineralization in the southern rio grande rift abstract as many as 29 mining districts along the rio grande rift in southern new mexico contain rio grande rift type rgr deposits consisting of fluorite barite sulfide jarosite and additional rgr deposits occur to the south in the basin and range province near chihuahua mexico jarosite occurs in many of these deposits as a late stage hydrothermal mineral coprecipitated with fluorite or in veinlets that crosscut barite in these deposits many of which are limestone hosted jarosite is followed by natrojarosite and is nested within silicified or argillized wallrock and a sequence of fluorite barite sulfide and late hematite gypsum these deposits range in age from 10 to 0 4 ma on the basis of 40ar 39ar dating of jarosite there is a crude north south distribution of ages with older deposits concentrated toward the south recent deposits also occur in the south but are confined to the central axis of the rift and are associated with modern geothermal systems the duration of hydrothermal jarosite mineralization in one of the deposits was approximately 1 0 my most 18oso4 oh values indicate that jarosite precipitated between 80 and 240 c which is consistent with the range of filling temperatures of fluid inclusions in late fluorite throughout the rift and in jarosite 180 c from pena blanca chihuahua mexico these temperatures along with mineral occurrence require that the jarosite have had a hydrothermal origin in a shallow steam heated environment wherein the low ph necessary for the precipitation of jarosite was achieved by the oxidation of h2s derived from deeper hydrothermal fluids the jarosite also has high trace element contents notably as and f and the jarosite parental fluids have calculated isotopic signatures similar to those of modern geothermal waters along the southern rift isotopic values range from those typical of meteoric water to those of deep brine that has been shown to form from the dissolution of permian evaporite by deeply circulating meteoric water jarosite 34s values range from 24 to 5 overlapping the values for barite and gypsum at the high end of the range and for sulfides at the low end most 34s values for barite are 10 6 to 13 1 and many 34s values for gypsum range from 13 1 to 13 9 indicating that a component of aqueous sulfate was derived from permian evaporites 34s 12 2 the requisite h2so4 for jarosite formation was derived from oxidation of h2s which was likely largely sour gas derived from the thermochemical reduction of permian sulfate the low 34s values for the precursor h2s probably resulted from exchange deeper in the basin with the more abundant permian so42 at 150 to 200 c jarosite formed at shallow levels after the ph buffering capacity of the host rock typically limestone was neutralized by precipitation of earlier minerals some limestone hosted deposits contain caves that may have been caused by the low ph of the deep basin fluids due to the addition of deep seated hf and other magmatic gases during periods of renewed rifting caves in other deposits may be due to sulfuric acid speleogenesis as a result of h2s incursion into oxygenated groundwaters the isotopic data in these sour gas jarosite occurrences encode a record of episodic tectonic or hydrologic processes that have operated in the rift over the last 10 my

late neogene to quaternary contractional structures in crete greece abstract based on geological and tectonic investigations carried out along an n s coast to coast transect across central crete southern aegean greece new meso and macro structural data mainly collected from neogene quaternary deposits are presented and discussed the occurrence of large scale folds and thrusts together with diffuse minor contractional structures as well as the overall geometry of the fault bounded sedimentary basins document the persistence of a tortonian early pleistocene contractional regime characterized by an nnw sse to nne ssw shortening direction and affecting the upper crust this contractional event s was associated with the ongoing hellenic subduction and caused the development of a southwards migrating out of sequence thrust system consisting of both reactivated inherited structures and new ones the new data emphasize the importance and the extent of this contractional event intervening between the early middle miocene exhumation phase and the still active upper crustal extensional regime that was resumed in the island only during pleistocene when the region was affected by diffuse normal faulting while the contractional event was likely due to a stronger coupling along the overall subduction system the onset of the new extensional stress conditions was probably related to a sudden southwards jump of the basal detachment along the lithospheric african subduction that caused a general stress release in the uppermost crust

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

clusters of megaearthquakes on upper plate faults control the eastern mediterranean hazard the hellenic subduction margin in the eastern mediterranean has generated devastating historical earthquakes and tsunamis with poorly known recurrence intervals here stranded paleoshorelines indicate strong uplift transients 0 7 mm yr along the island of crete during the last 50 kyr due to earthquake clustering we identify the highest uplift rates in western crete since the demise of the minoan civilization and along the entire island between 10 and 20 kyr b p with the absence of uplifted late holocene paleoshorelines in the east being due to seismic quiescence numerical models show that uplift along the hellenic margin is primarily achieved by great earthquakes on major reverse faults in the upper plate with little contribution from plate interface slip these earthquakes were strongly clustered with recurrence intervals ranging from hundreds to thousands of years and primarily being achieved by fault interactions future great earthquakes will rupture seismically quiet areas in eastern crete elevating both seismic and tsunami hazards

geostatistics based regional characterization of groundwater chemistry in a sedimentary rock area with faulted setting sophisticated modeling of a hydrogeological structure and the environment are crucial for underground construction this study characterizes hydrochemical properties of groundwater in a sedimentary rock area clarifying their spatial distribution and correlation with geologic structure and interpreting the groundwater source and chemical evolution water samples geological columns and well logs to 1 km depth were taken at 10 sites in horonobe of northern japan toward the objectives a 3d model of cl concentration was produced in conjunction with resistivity logging data through kriging estimation and sequential gaussian cosimulation variography shows that the dip of the main omagari fault is a control on the spatial correlation structure of cl concentration the 3d model shows that this fault and its auxiliary constitute a clear boundary between high and low saline waters and that cl concentrations tend to change in accord with sedimentary layer structures the integration of stable isotope analysis suggests that deep saline water with heavy d and 18o originated from fossilized seawater whereas shallow freshwater with light values is of meteoric water origin dilute saline water in the deep part of study area is partially attributable to dehydration of silica minerals vertical and lateral groundwater flows are estimated to prevail near the omagari fault and be general in other zones respectively difference in the depth of transition zones may be caused by the dominant flow among downward ascending and lateral consequently geostatistical techniques and data integration are useful to depict regional groundwater systems with a data set of water investigation limited by quantity and location

geometry and kinematics of active faults and their seismotectonic significance in the western corinth patras rift greece abstract the western part of the corinth patras rift is formed in an area which is being uplifted rifted domains have subsided relative to the adjacent areas in nw peloponnesus and sterea hellas but subsidence rates rarely exceed uplift rates extension is mainly accomplished by wnw trending active faults with lengths up to 25 km most of these faults show an along strike segmentation and often terminate against transfer faults displacement analysis along 170 mesoscopic faults and 36 mappable faults has been carried out to assess slip rates and to estimate the magnitudes and recurrence time intervals of earthquakes occurring along them earthquake magnitude ranges between 5 and 6 7 only eight faults appear to be capable of producing earthquake magnitudes larger than 6 recurrence times of these large earthquakes vary between 80 and 1690 years upper crustal deformation in the western corinth graben can be described by six large asymmetric grabens which are inferred to bottom out to a n dipping curved ramp the asymmetric shape of most wnw trending rifts in the hellenic peninsula including the corinth patras rift promotes the simple shear model of extension against the pure shear model in the upper crustal layer

the 2008 methoni earthquake sequence the relationship between the earthquake cycle on the subduction interface and coastal uplift in sw greece ah is supported by a shell exploration studentship this study forms part of the nerc and esrc funded project earthquakes without frontiers under grant nej02001x 1 and was partly funded by the nerc grant looking inside the continents from space

mineral control of arsenic content in thermal waters from volcano hosted hydrothermal systems insights from island of ischia and phlegrean fields campanian volcanic province italy this paper documents arsenic concentrations in 157 groundwater samples from the island of ischia and the phlegrean fields two of the most active volcano hosted hydrothermal systems from the campanian volcanic province southern italy in an attempt to identify the environmental conditions and mineral solution reactions governing arsenic aqueous cycling on ischia and in the phlegrean fields groundwaters range in composition from nacl brines which we interpret as the surface discharge of deep reservoir fluids to shallow depth circulating fluids the latter ranging from acid sulphate steam heated to hypothermal cold bicarbonate groundwaters arsenic concentrations range from 1 6 to 6900 g l 1 and from 2 6 to 3800 g l 1 in the phlegrean fields and on ischia respectively they increase with increasing water temperature and chlorine contents and in the sequence bicarbonate groundwatersbsteam heated groundwatersbnacl brines according to thermochemical modeling we propose that high as concentrations in nacl brines form after prolonged water rock interactions at reservoir t fo2 and fh2s conditions and under the buffering action of an arsenopyrite pyrite pyrrhotite rock assemblage on their ascent toward the surface nacl brines become diluted by as depleted meteoric derived bicarbonate groundwaters giving rise to hybrid water types with intermediate to low as contents steam heated groundwaters give their intermediate to high as concentrations to extensive rock leaching promoted by interaction with as bearing hydrothermal steam 2005 elsevier b v all rights reserved

displacement rates of normal faults previous estimates of displacement rates on individual faults have been limited to neotectonic faults and averaged over time intervals of about 200 kyr or less1 2 3 4 5 these estimates have been highly variable which has led to a belief that longer term displacement rates on individual faults are likely to be variable as well here we report estimates of long term normal fault displacement rates averaged over time intervals ranging from 1 to 40 myr and based on observed decreases in displacement of progressively younger horizons intersected by syn sedimentary faults we find that displacement rates are remarkably stable over these longer time periods and within a given fault system the rates are strongly dependent on the relative size of the fault as measured by cumulative vertical displacement taken together these results indicate that faults become large relative to nearby faults by having higher displacement rates even when small rather than as a consequence of having been active for longer our analyses also show that high regional strain rates tend to be accommodated by high fault displacement rates rather than high fault densities

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

present day crustal stress field in greece inferred from regional scale damped inversion of earthquake focal mechanisms in this study we utilize regional and teleseismic earthquake moment tensor solutions in order to infer the contemporary crustal stress in the greek region we focus on crustal earthquakes and select only solutions with good waveform fits and well resolved nodal planes a data set of 1614 focal mechanisms is used as input to a regional scale damped stress inversion algorithm over a grid whose node spacing is 0 35 several resolution and sensitivity tests are performed in order to ascertain the robustness of our results our findings show that for most of the greek region the largest principal stress 1 is vertically oriented and that the minimum principal stress axis 3 are subhorizontal with a predominant n s orientation in the sw peloponnese the orientation of 3 axes rotates clockwise and in se aegean counterclockwise these results are in agreement with the generally accepted model that slab rollback combined with gravitational spreading of the aegean lithosphere are the main causes of the extension transitions between different faulting types in nw greece or in the aegean occur within narrow zones in the order of tens of kilometers a visual comparison of the principal horizontal stress axes and the principal strain axes derived from gps observations shows good agreement suggesting that the crust in the greek region behaves largely in an elastic manner

an alternative model for the growth of faults conventional growth models suggest that faults become larger due to systematic increases in both maximum displacement and length we propose an alternative growth model where fault lengths are near constant from an early stage and growth is achieved mainly by increase in cumulative displacement the model reconciles the scaling properties of faults and earthquakes and predicts a progressive increase in fault displacement to length ratios as a fault system matures this growth scheme is directly applicable to reactivated fault systems in which fault lengths were inherited from underlying structure and established rapidly the model may also apply to some non reactivated fault systems near constant fault lengths during subsequent growth are attributed to retardation of lateral propagation by interaction between fault tips the model is validated using kinematic constraints from growth strata which are displaced by a system of reactivated normal faults in the timor sea nw australia

displacement and geometrical characteristics of earthquake surface ruptures issues and implications for seismic hazard analysis and the process of earthquake rupture there now exist about three dozen historical earthquakes for which in vestigators have constructed maps of earthquake rupture traces accompanied by de scriptions of the coseismic slip observed along the fault strike the maps and slip distributions are compiled here to place observational bounds on aspects of seismic hazard analysis and fault mechanics analysis leads to an initial statistical basis to predict the end points of rupture and the amount of surface slip expected at sites along the strike during earthquakes on mapped faults the observations also give support to the ideas that there exists a process zone or volume of about 3 4 km in dimension at the fronts of large laterally propagating earthquake ruptures within which stress changes may be sufficient to trigger slip on adjacent faults and that the ultimate length of earthquake ruptures is controlled primarily by the geometrical complexity of fault traces and variations in accumulated stress levels along faults that arise due to the location of past earthquakes to this may be added the observation that the form of earthquake surface slip distributions is better described by asymmetric rather than symmetric curve forms and that earthquake epicenters do not appear to correlate in any systematic manner to regions of maximum surface slip observed along strike online material maps of surface ruptures digitized values and curve fits to surface slip distributions and notes and references for tables 1 and 2