reassessment of the rifting process in the western corinth rift from relocated seismicity the seismic activity in the western part of the corinth rift greece over the period 2000 2007 monitored by a dense network of three component stations is analysed in terms of multiplets and high precision relocation using double difference techniques this detailed analysis provides new insights into the geometry of faults at depth the nature and the structure of the active zone at 6 8 km depth previously interpreted as a possible detachment and more generally into the rifting process the seismicity exhibits a complex structure strongly varying along the rift axis the detailed picture of the seismic zone below the rift indicates that its shallower part at depths of 6 8 km is 1 1 5 km thick with a complex microstructure and that its deeper part at depths of 9 12 km gently dipping to the north 10 20 is 0 1 0 3 km thick with a microstructure consistent with the general slope of the structure although the nature of this seismic zone remains an open question the presence of seismicity beneath the main active area the strong variability of the structure along the rift over short distances and the complex microstructure of the shallower part revealed by the multiplet analysis are arguments against the hypothesis of a mature detachment under the rift this active zone more likely represents a layer of diffuse deformation the geometry of the mapped active faults is not well defined at depth as no seismicity is observed between 0 and 4 km except for the aigion fault rooting in the seismic layer at 6 km depth with a dip of 60 a distinct cloud of seismicity may be associated with the antithetic kalithea fault on which the 1909 fokis earthquake m s 6 3 may have occurred the link between the 1995 rupture m s 6 2 and the faults known at the surface has been better constrained as the relocated seismicity favours a rupture on an offshore blind fault dipping at 30 rather than on the deeper part of the east helike fault consequently the 1995 event is expected to have decreased the coulomb stress on the east helike fault to explain these seismic observations along with the geodetic observations a new mechanical model for the rifting process in this region is proposed involving non elastic mostly aseismic uniform ns opening below the rift axis coupled with the downward and northward growth of a yet immature detachment the reported gps rates would mainly result from this deep silent source and the seismicity would reveal the detachment position not yet connected to the ductile lower crust in such a model the strong fluctuations of microseismicity would result from small strain instabilities undetected by continuous gps and possibly related to pore pressure transients

geomorphic and biological indicators of paleoseismicity and holocene uplift rate at a coastal normal fault footwall western corinth gulf greece abstract the westernmost part of the gulf of corinth greece is an area of very fast extension and active normal faulting accompanied by intense coastal uplift and high seismicity this study presents geomorphic and biological evidence of holocene coastal uplift at the western extremity of the gulf where such evidence was previously unknown narrow shore platforms benches and rare notches occur mainly on holocene littoral conglomerates of uplifting small fan deltas they are perhaps the only primary paleoseismic evidence likely to provide information on earthquake recurrence on coastal faults in the specific part of the rift whereas dated marine fauna can provide constraints on the average holocene coastal uplift rate the types of geomorphic and biological evidence identified are not ideal and there are limitations and pitfalls involved in their evaluation in a first approach 5 uplifted paleoshorelines may be identified at 0 4 0 7 1 0 1 3 1 4 1 7 2 0 2 3 and 2 8 3 4 m a m s l probably forming after 1728 or 2250 cal b p a most conservative estimate for the average coastal uplift rate during the late holocene is 1 6 or 1 9 mm yr minimum with different amounts of reservoir correction some of the obtained radiocarbon ages of lithophaga sp allow for much higher holocene uplift rates of the order of 3 4 mm yr which cannot be discarded but require further research that the identified paleoshoreline record corresponds to episodes of coastal uplift only cannot be demonstrated beyond all doubt yet it appears the most likely interpretation given the geological and active tectonic context and present knowledge on eustatic sea level fluctuations in the mediterranean proving that the documented uplifts were abrupt i e arguably coseismic is equally difficult but rather probable five earthquakes in the last ca 2000 yr on the coastal fault zone that is responsible for the uplift compare well with historical seismicity and the results of recent on fault paleoseismological studies at the nearby eliki fault zone exact amounts of coseismic uplift cannot be determined precisely unless the rate of non seismic uplift of northern peloponnesus at the specific part of the corinth rift is somehow constrained

the 1986 kalamata south peloponnesus earthquake detailed study of a normal fault evidences for east west extension in the hellenic arc tectonic and seismological data collected in the field following the september 13 1986 kalamata earthquake south peloponnesus are presented and analyzed to discuss the earthquake rupture process and the regional tectonics the event occurred on the kalamata normal fault whose trace was mapped with spot images and topographic and field observations this fault is part of an approximately nnw sse en echelon system cutting through the hellenic nappes the fault striking n15 e on the average with a dip of about 50 has a minimum cumulated quaternary throw of the order of 1 km the measured coseismic slip is 6 18 cm over a length of 6 km the main shock focal mechanism obtained from long period waveform modeling strike 201 10 20 dip 45 5 rake 283 10 25 represents almost pure east west extension and is in good agreement with tectonic observations the centroid depth is constrained to 5 3 km and the seismic moment to 7 0 2 5 1017 n m over 700 aftershocks located by a 16 station network installed after the earthquake for a period of 2 weeks define two clusters separated by a gap of aftershock activity from the surface to a depth of about 10 km the main cluster to the south defines a 45 west dipping plane which lies on the downward extension of the fault mapped at the surface focal mechanisms of aftershocks on this fault plane are homogeneous and represent e w extension as the main shock in contrast the majority of focal mechanisms in the uppermost part of the foot wall show more or less e w compression probably corresponding to postseismic stress release the northern cluster of aftershocks is very dense and located away from the surface rupture within a relay zone between the kalamata and the next en echelon faults to the nw the thouria faults there focal mechanisms represent extension from about n115 to n70 and n20 corresponding mostly to fault reactivation in an area where nonrigid deformations prevail the main shock probably initiated in this relay zone 3 4 s before the rupture front reached the main fault plane and released most of the energy there the rupture presumably propagating southward the focal mechanism of the kalamata earthquake and that of the april 27 1965 earthquake located to the northwest of crete as well as the regional active normal fault pattern imply that e w extension oblique to the hellenic arc is presently the dominant tectonic regime e w stretching occurs partly on reactivated nw se faults parallel to the hellenic structures but mostly on newly formed n s normal faults across those structures the latter faults are responsible for the apparent segmentation of the hellenic belt from southern peloponnesus to crete the existence of active e w extension in this region implies a recent change in the tectonic regime and consequently a change in boundary conditions at the subduction zone probably in response to the incoming margin of africa

coastal uplift on active normal faults the eliki fault greece the eliki fault forms part of a system of major normal fault segments that borders the southern margin of the gulf of corinth half graben radiocarbon dating of elevated marine fossils reveals broadly uniform holocene coastal uplift at a time averaged rate of 1 5 mm yr both along the eliki fault and in the transfer zone that separates it from the neighbouring fault segment coseismic uplift increments are considered to account for only a minor part of the 6 m of emergence recorded here in the last 3000 years reappraisal of shoreline data from the perachora peninsula at the eastern end of the gulf of corinth indicates a similar though less rapid 0 7 mm yr pattern of uniform holocene emergence as these holocene coastal records embody both coseismic and interseismic deformation they can be used to characterise long term tectonic strain

holocene and quaternary uplift in the central part of the southern coast of the corinth gulf greece abstract the southern coast of the gulf of corinth greece has long been recognized as an area of rapid quaternary uplift in a normal faulting environment but the amplitude dating and significance of this uplift remain a matter of debate mainly due to the scarcity of reliable and detailed estimates of holocene and longer term uplift evidence of holocene emergence is analysed for two sites in the most uplifted area of the southern coast of the gulf of corinth at mavra litharia the uppermost holocene marine limit has been identified at 9 3 m and dated about 7100 14 c years bp near platanos where the holocene marine limit is above 12 5 m in situ infralittoral boring shells at 11 5 m have been dated about 4800 14 c years bp average uplift rates can be estimated between 2 9 and 3 5 mm year at mavra litharia and possibly even greater ca 2 1 2 7 mm year near platanos the pattern of the variation of holocene uplift along the coast seems to mimic the pattern of late quaternary terraces well constrained in the eastern pattern of the gulf corinth xylokastro area

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

seismic source parameter relations for earthquakes in greece a data set of nineteen mainly shallow moderate to large earthquakes which occurred in the aegean and the surrounding area has been used to derive empirical relations for kinematic fault parameters thus the relations between seismic momentm 0 and magnitudem s andm b and betweenm 0 andm s and fault dimensionss andl have been determined from these relations and theoretical ones it was deduced that earthquakes in the aegean and the surrounding events chiefly interplate are characterized by low average stress drop values values of ranging from 1 to 30 bar are consistent with the data it was also found that in general terms most of the data obey the geometrical similarity conditionl 2w wherel is the fault length measured along the strike andw is its width measured along the dip for strike slip faults however the conditionl 4w seems to hold

radiometric dates of uplifted marine fauna in greece implications for the interpretation of recent earthquake and tectonic histories using lithophagid dates n ad 365 a great mw n 8 earthquake lifted up western crete exposing a shoreline encrusted by marine organisms and up to 10 m of marine substrate beneath it radiocarbon ages determined for corals and bryozoans exposed between the paleo shoreline and present sea level are consistent within measurement error with each other and with the date of the earthquake but radiocarbon ages determined for the boring bivalve lithophaga lithophaga found on the same substrate are at least 350 years and up to 2000 years older than the date of the earthquake that lifted them above sea level these observations reveal two important effects that limit the use of radiocarbon lithophagid ages in tectonic and paleoseismological studies the first is that the exceptional preservation potential of lithophagids allows them to remain intact and in situ long after natural death while the substrate continues to be colonised until eventual uplift the second which we confirm with radiocarbon analysis of museum specimens of known age is the incorporation of old 14c free carbon into lithophagid shells from the limestone host rock into which the lithophagids bored the two effects are both significant in crete and central greece and can cause the radiocarbon lithophagid ages to be up to 2000 years older than the uplift event which exposed them understanding these effects is important because lithophagids are far more abundantly preserved and used to date uplift than most other marine organisms this study shows that they can rarely be used to distinguish uplift events or date them to better than 1000 years or even to distinguish whether observed uplift occurred in a single or in multiple events after taking account of these uncertainties the ages of the lithophagids are however consistent with the hypothesis that the highest prominent marine notches and exposed lithophagid holes within a few metres of sea level in greece formed when sea level became relatively stable 6000 years ago following rapid rise after the last glacial maximum

large eighteenth nineteenth century earthquakes in western gulf of corinth with reappraised size and location abstract the area of the western gulf of corinth around the city of aigio achaea northwest peloponnese greece represents an international pilot site for continuous monitoring and multidisciplinary research on earthquake processes in the framework of the anr siscor corinth rift laboratory project 2011 2014 a thorough reappraisal of the five largest m w 6 eighteenth nineteenth century earthquakes was performed namely those of 14 may 1748 23 august 1817 26 december 1861 9 september 1888 and 25 august 1889 written observations of earthquake effects were looked into in their original version and language and were placed in the context from which they originated to avoid the translations and digests on which previous seismological studies had relied earthquake records were traced for 108 different localities and 143 macroseismic intensities in european macroseismic scale 1998 ems 98 have been assigned earthquake related geological phenomena have been identified and carefully mapped to be used as a further constraint of the location and magnitude of the associated earthquakes finally new parameters for the studied earthquakes have been assessed with two separate and independent strategies to quantify epistemic uncertainties in conclusion the 1748 1817 and 1888 earthquakes were located in the area of aigio the 1861 earthquake is reckoned to be the largest in the area with an epicentral location at sea whereas the 1889 earthquake has been relocated to the northwest in mainland greece well outside the gulf of corinth electronic supplement additional material and intensity values in european macroseismic scale 1998 ems 98 for the five studied earthquakes and tests on deriving earthquake parameters

sequence stratigraphy in active extensional basins implications for the interpretation of ancient basin fills abstract systematic variations in sequences their component units and their stacking patterns exist within rift basins these variations can be related to displacement gradients associated with the large scale 12 50 km segmentation of normal fault zones which control accommodation sediment supply and basin physiography sediment supply is also strongly influenced by the nature of pre rift drainage networks and variations in bedrock lithology high rates of hangingwall subsidence close to the centre of normal fault segments may cancel out the effects of glacio eustatic sea level fall so that accommodation development is normally characterized by the continual addition of new space the resulting sequences lack type 1 sequence boundaries and lowstand systems tracts and stack into aggradational sequence sets the adjacent footwall is subject to uplift which may lead to subaerial exposure and incision generating a composite type 1 sequence boundary away from the fault zone and near segment boundaries slip rates are much lower and hence relative sea level change is dominated by eustasy here falls in relative sea level are important resulting in type 1 sequences sequence stacking patterns reflect not only eustasy and local fault controlled subsidence but also the interaction of these with adjacent uplifting footwalls and or regional uplift tectonic influence on sequence development will be more pronounced during greenhouse times than icehouse times

liquefaction ground fissures and coastline change during the egio earthquake 15 june 1995 central western greece the destructive earthquake ms 6 1 r that hit the town of egio and the surrounding area of the northern peloponnessos greece generated extensive liquefaction ground fissuring and coastline changes historical data indicate that the same region has experienced episodic earthquake damage with some seismogenic phenomena having reoccurred at the same locations in conclusion it is confirmed that this is a high seismic risk region where proper building design and planning can reduce the potential danger if the geodynamic setting is properly taken into account

the helice fault the site of the ancient greek city of helice which was destroyed by an earthquake in 373 bc has never been found we propose that it was submerged as the result of seismic slip on a normal fault traceable se of egion and that the fault was reactivated in 1881 when schmidt reported a fresh scarp 2 m high and 13 km in length at the same locality earlier movements on the fault are inferred from lithophaga borings on coastal sectors of the footwall which yield 14c ages representing over 6 5 m of uplift in the last 4880 years

a palaeoseismological and geoarchaeological investigation of the eliki fault gulf of corinth greece abstract palaeoseismological and morphotectonic analyses enable us to define a 400 m wide actively deformed zone associated with the active eliki normal fault central greece bounded on the south by a second order fault and on the north by a composite and prominent fault scarp this scarp is further analysed by trenching based on colluvium stratigraphy displacement of distinct horizons and deposition of sedimentary layers three faulting events have been identified along four fault strands affecting unconsolidated sediments in the trench the two younger events with throws of 0 93 and 1 37 m respectively the third event with a throw of 0 44 m and the penultimate 373 bc event suggest a variable seismic history the entire alluvial plain of the kerynitis and vouraikos rivers which cross the eliki fault has subsided at a rate of 1 4 mm year resulting in the burial of the late hellenistic roman occupation horizons under 3 m of fluvial and colluvial sediments in places extension in the broader area is accommodated by the seismically active eliki and egion faults structural and palaeoseismological analysis of those two faults indicates that they accommodate 1 5 mm year or about 10 of the geodetically estimated extension of up to 13 mm year

recent history of the eastern eliki fault gulf of corinth geomorphology palaeoseismology and impact on palaeoenvironments summary the eliki fault system dominates the landscape of the southwestern shore of the gulf of corinth where rapid extension rates result in frequent earthquakes these include an event in 373 bc that destroyed the city of helike and a recent event in 1861 uplifted late pleistocene marine terraces within the eastern eliki fault footwall suggest revised slip rates of 3 5 mm yr 1 contributing 2 3 mm yr 1 geological extension to a net geodetic extension of 10 15 mm yr 1 across this part of the rift palaeoseismological trenches indicate two and possibly three earthquakes on the eastern eliki fault in the last 1500 yr including the 1861 earthquake one trench eet1a reveals displaced stratigraphy but the main fault trace is thought to lie further south beneath the old national road trench eet1a reveals liquefied sediments associated with an event between ad 1460 and the present which may be the 1861 event and displacement during a second event in the interval ad 440 1410 or ad 1270 1640 a third earlier event identified by liquefaction occurred on the eliki or a nearby fault in ad 440 1410 using the 1861 and second event most likely ad 1270 1640 the interval between recent earthquakes is 200 600 yr suitable trench sites are rare in this region compounded by human activity over several thousand years borehole and trench data indicate that the kerynites river frequently flowed eastwards along the eastern eliki fault during the last 20 40 kyr possibly influenced by tectonic tilting from the eliki and aigion fault systems and natural channel avulsion

renewal models and coseismic stress transfer in the corinth gulf greece fault system 1 we model interevent times and coulomb static stress transfer on the rupture segments along the corinth gulf extension zone a region with a wealth of observations on strong earthquake recurrence behavior from the available information on past seismic activity we have identified eight segments without significant overlapping that are aligned along the southern boundary of the corinth rift we aim to test if strong earthquakes on these segments are characterized by some kind of time predictable behavior rather than by complete randomness the rationale for time predictable behavior is based on the characteristic earthquake hypothesis the necessary ingredients of which are a known faulting geometry and slip rate the tectonic loading rate is characterized by slip of 6 mm yr on the westernmost fault segment diminishing to 4 mm yr on the easternmost segment based on the most reliable geodetic data in this study we employ statistical and physical modeling to account for stress transfer among these fault segments the statistical modeling is based on the definition of a probability density distribution of the interevent times for each segment both the brownian passage time bpt and weibull distributions are tested the time dependent hazard rate thus obtained is then modified by the inclusion of a permanent physical effect due to the coulomb static stress change caused by failure of neighboring faults since the latest characteristic earthquake on the fault of interest the validity of the renewal model is assessed retrospectively using the data of the last 300 years by comparison with a plain time independent poisson model by means of statistical tools including the relative operating characteristic diagram the r score the probability gain and the log likelihood ratio we treat the uncertainties in the parameters of each examined fault source such as linear dimensions depth of the fault center focal mechanism recurrence time coseismic slip and aperiodicity of the statistical distribution by a monte carlo technique the monte carlo samples for all these parameters are drawn from a uniform distribution within their uncertainty limits we find that the bpt and the weibull renewal models yield comparable results and both of them perform significantly better than the poisson hypothesis no clear performance enhancement is achieved by the introduction of the coulomb static stress change into the renewal model

oceans in the icy galilean satellites of jupiter abstract equilibrium models of heat transfer by heat conduction and thermal convection show that the three satellites of jupiter europa ganymede and callisto may have internal oceans underneath ice shells tens of kilometers to more than a hundred kilometers thick a wide range of rheology and heat transfer parameter values and present day heat production rates have been considered the rheology was cast in terms of a reference viscosity 0 calculated at the melting temperature and the rate of change a of viscosity with inverse homologous temperature the temperature dependence of the thermal conductivity k of ice i has been taken into account by calculating the average conductivity along the temperature profile heating rates are based on a chondritic radiogenic heating rate of 4 5 pw kg 1 but have been varied around this value over a wide range the phase diagrams of h2o ice i and h2o 5 wt nh3 ice have been considered the ice i models are worst case scenarios for the existence of a subsurface liquid water ocean because ice i has the highest possible melting temperature and the highest thermal conductivity of candidate ices and the assumption of equilibrium ignores the contribution to ice shell heating from deep interior cooling in the context of ice i models we find that europa is the satellite most likely to have a subsurface liquid ocean even with radiogenic heating alone the ocean is tens of kilometers thick in the nominal model if tidal heating is invoked the ocean will be much thicker and the ice shell will be a few tens of kilometers thick ganymede and callisto have frozen their oceans in the nominal ice i models but since these models represent the worst case scenario it is conceivable that these satellites also have oceans at the present time the most important factor working against the existence of subsurface oceans is contamination of the outer ice shell by rock rock increases the density and the pressure gradient and shifts the triple point of ice i to shallower depths where the temperature is likely to be lower then the triple point temperature according to present knowledge of ice phase diagrams ammonia produces one of the largest reductions of the melting temperature if we assume a bulk concentration of 5 wt ammonia we find that all the satellites have substantial oceans for a model of europa heated only by radiogenic decay the ice shell will be a few tens of kilometers thinner than in the ice i case the underlying rock mantle will limit the depth of the ocean to 80 100 km for ganymede and callisto the ice i shell on top of the h2o nh3 ocean will be around 60 to 80 km thick and the oceans may be 200 to 350 km deep previous models have suggested that efficient convection in the ice will freeze any existing ocean the present conclusions are different mainly because they are based on a parameterization of convective heat transport in fluids with strongly temperature dependent viscosity rather than a parameterization derived from constant viscosity convection models the present parameterization introduces a conductive stagnant lid at the expense of the thickness of the convecting sublayer if the latter exists at all the stagnant lid causes the temperature in the sublayer to be warmer than in a comparable constant viscosity convecting layer we have further modified the parameterization to account for the strong increase in homologous temperature and therefore decrease in viscosity with depth along an adiabat this modification causes even thicker stagnant lids and further elevated temperatures in the well mixed sublayer it is the stagnant lid and the comparatively large temperature in the sublayer that frustrates ocean freezing

a possible normal fault rupture for the 464 bc sparta earthquake surface ruptures have been identified for some normal faulting earthquakes in the aegean region1 3 but for most historical earthquakes the associated faults are unknown this hampers the evaluation of the rates and styles of present day deformation and the assessment of seismic hazard in the region4 here we examine the famous earthquake that destroyed sparta in 464 bc using spot satellite images and fieldwork we have mapped a 20 km long normal fault scarp trending approximately north south a few kilometres east of the ancient city our observations combined with an examination of historical descriptions of the earthquake damage suggest that the sparta earthquake ruptured this fault scarp in an event of magnitude ms 7 2 the holocene slip rate and the recurrence time for such large events on the sparta fault would be 1 mm yr 1 and 3 000 yr respectively

synthetic earthquake catalogs simulating seismic activity in the corinth gulf greece fault system the characteristic earthquake hypothesis is the basis of time dependent modeling of earthquake recurrence on major faults however the characteristic earthquake hypothesis is not strongly supported by observational data few fault segments have long historical or paleoseismic records of individually dated ruptures and when data and parameter uncertainties are allowed for the form of the recurrence distribution is difficult to establish this is the case for instance of the corinth gulf fault system cgfs for which documents about strong earthquakes exist for at least 2000 years although they can be considered complete for m 6 0 only for the latest 300 years during which only few characteristic earthquakes are reported for individual fault segments the use of a physics based earthquake simulator has allowed the production of catalogs lasting 100 000 years and containing more than 500 000 events of magnitudes 4 0 the main features of our simulation algorithm are 1 an average slip rate released by earthquakes for every single segment in the investigated fault system 2 heuristic procedures for rupture growth and stop leading to a self organized earthquake magnitude distribution 3 the interaction between earthquake sources and 4 the effect of minor earthquakes in redistributing stress the application of our simulation algorithm to the cgfs has shown realistic features in time space and magnitude behavior of the seismicity these features include long term periodicity of strong earthquakes short term clustering of both strong and smaller events and a realistic earthquake magnitude distribution departing from the gutenberg richter distribution in the higher magnitude range

direct geological evidence for prior earthquakes on the 1981 corinth fault central greece we present the preliminary results of geomorphic and trench investigations at the eastern end of a scarp produced by the 1981 corinth earthquake sequence at this site the 1981 rupture produced average vertical displacements of 0 6 0 7 m maximum 1 3 m that in part occurred along a cumulative scarp which displaces the fan surface by up to 5 m based on this cumulative scarp displacing the holocene fan surface we estimate a vertical slip rate of 1 mm yr that translates to 1 mm yr n s extension we found evidence for two individual pre 1981 earthquakes which occurred on the basis of preliminary radiocarbon dating on two paleosols shortly after a d 590 and a d 1295 each of these events produced a vertical displacement ranging between 0 5 and 1 2 m hence comparable to the 1981 scarp height this suggests that coseismic slip may have been characteristic at this location over the past three seismic cycles following this hypothesis and assuming a periodic strain release a maximum recurrence interval of 700 yr is calculated these results indicate that the 1981 surface breaking faults accommodate only part of the regional extension deduced from the geodetic measurements

magnitude versus faults surface parameters quantitative relationships from the aegean region historical and seismotectonic data from the broader aegean region have been collected and all possible information relative to ground deformation associated to earthquakes that hit the area have been re evaluated all events associated to co seismic surface faulting have been selected and further investigated while geomorphologic and geological criteria have been used to recognise and characterise the seismogenic faults associated to these morphogenic earthquakes sensu bull inqua 16 1993 24 in particular in order to perform seismic hazard analyses we compiled a list of all earthquakes where the surface rupture length srl the maximum vertical displacement mvd or the average displacement ad is available we thus obtained reliable values of these source parameters for 36 earthquakes of which 26 occurred during the 20th century 6 in the 19th century and the 3 remaining earlier magnitude versus srl and mvd has been compiled for estimating empirical relationships the calculated regression equations are ms 0 90 log srl 5 48 and ms 0 5 9log mvd 6 75 showing good correlation coefficients equal to 0 84 and 0 82 respectively co seismic fault rupture lengths and especially maximum displacements in the aegean region have systematically lower values than the same parameters worldwide but are similar to those of the eastern mediterranean middle east region the envelopes of our diagrams are also calculated and discussed for estimating the worst case scenario furthermore for all investigated seismogenic structures based on several geological criteria we measured the geological fault length gfl which is the total length of the neotectonic faults showing cumulative recent activity we then compared srl with gfl and their ratio shows a clear bimodal distribution with a major peak at 0 8 1 0 indicating that about 50 of the investigated earthquakes ruptured almost the entire fault length while a second peak around the value of 0 5 is clearly related to a segmentation process of longer neotectonic structures further implications of this distribution are also discussed eventually from the distribution of gfl versus magnitude we also infer an important geological threshold for the occurrence of morphogenic earthquakes at about 5 5 degrees

alluvial cover dynamics in response to floods of various magnitudes the effect of the release of glaciogenic material in a swiss alpine catchment abstract fluvial incision into formerly glaciated landscapes is commonly affected by the release of glaciogenic sediments from the hillslopes via landsliding hillslope failure and debris flow activity these deposits typically comprise abundant block size clasts here we determine the ability of the fluvial processes to evacuate glacially derived sediments in an alpine hanging valley blanketed by 100 m thick glacial till we assess along stream profiles of basal shear stress during annual decadal and centennial floods by means of the hydrological model hec ras we use bed surface grain size data to i evaluate the shields stress profiles for these floods ii determine at which timescale the bed undergoes significant changes and to iii predict transport capacity patterns for each flood in addition we present digital photogrammetry based estimates of bed elevation changes over two selected time intervals that experienced low and high magnitude floods respectively the results indicate that floods with return periods of 10 years are capable of mobilizing the coarse fraction of the bed material thereby substantially altering the channel geometry the predicted near critical shields stress values for these floods in the area where the glacial deposits are thickest suggest a strong hillslope channel coupling which may have resulted in the formation of the knickzone observed in this sector however decadal to centennial floods are required to transport the material over long distances and scour the bed in the upper part of the inner gorge in addition the observed downstream trend from bed scouring to deposition in the inner gorge for these floods and the opposite trend for low magnitude floods suggest that these patterns are not directly controlled by downstream variations of transport capacity we propose that the supply of sediment through hillslope failure and bank collapse significantly contributes to the sediment flux for high magnitude floods we conclude that the morphology and the timescale of sediment transport in this glacially conditioned landscape have been substantially controlled by the hillslope derived supply of coarse grained material

slip rates on the helike fault gulf of corinth greece new evidence from geoarchaeology palaeoseismological and archaeological analysis of a trench enabled us to estimate the holocene slip rates on the east helike fault flanking the south western gulf of corinth we recognized two major fault strands within the trench the north fault controls a succession of three colluvial wedges and the deposition of a 2 7 m thick sedimentary sequence the south fault controls the deposition of a 2 9 m thick brownishred colluvium based on colluvial stratigraphy radiocarbon dating of the sediments suggests that the slip rate was c 0 3 mm yr 1 from 10 250 to c 1400 bp when it increased dramatically to c 2 0 mm yr 1 after a strong earthquake event near 1400 bp the faster slip rate evidently increased the sedimentation rate

implications of structural segmentation during earthquakes the 1995 egion earthquake gulf of corinth greece the egion earthquake which occurred in the gulf of corinth central greece ms 6 2 on 15 june 1995 was caused by normal slip on the north dipping and wnw trending egion fault the egion fault ruptured at depth during the egion mainshock and probably re ruptured at shallow level during the largest aftershock the surface trace of the egion fault has a segmented geometry linkage between three segments which show long term deformation differences as well as coseismic segmentation enabled all segments to be incorporated in an earthquake segment the surface ruptures continued to grow after the coseismic motion the afterslip throw of the fault 10 weeks after the main event was equal to the 3 cm value for maximum coseismic slip this afterslip was accompanied by uplift of the footwall block and a warp like hangingwall subsidence folding this pattern of deformation was associated with more complex deformation at the western end of the earthquake segment here afterslip was accompanied by general subsidence of the whole area between 25th june and 30th july followed by uplift of the whole area without afterslip between 30th july and 2nd september the afterslip rate averaged over the 73 day period after the main event varied from 0 48 mm day 1 along the central part of the earthquake segment to 0 16 mm day 1 at the eastern end of the earthquake segment

paleoseismicity of the 1981 corinth earthquake fault seismic contribution to extensional strain in central greece and implications for seismic hazard we present paleoseismological trenching results for the active skinos fault which ruptured the surface on the alkyonides gulf basin margin in the 1981 gulf of corinth earthquake sequence three trenches expose evidence of up to six previous events which are comparable to the 1981 deformation in terms of size and geometry vertical displacement produced by the 1981 earthquake ranged from 0 45 to 1 3 m at the bambakies fan trench sites decreasing towards the eastern fault tip east of the trenches trench 1 reveals two previous events with vertical displacements between 0 5 and 1 2 m since 390 a d trench 2 reveals five or six previous events but these are not dated trench 3 reveals four previous events since 670 a d vertical displacements associated with interpreted paleoearthquakes at the trench sites are 1 2 m the recurrence interval on the skinos fault is estimated to average 330 years however significant variation in recurrence interval is allowed by the available radiometric dates average vertical displacement rates derived from the trenches are in the range 0 7 2 5 mm yr a similar long term average vertical displacement rate of 1 2 2 3 mm yr is estimated for the lifespan of the basin bounding fault this equates to a horizontal seismic strain contribution of 2 5 mm yr from the skinos fault this local seismic strain rate overlaps within error with geodetically determined velocities across the alkyonides gulf assumed to represent uniform deep crustal strain thus seismic deformation on the basin bounding fault system may take up the major part of extension across the basin and aseismic strain is not necessitated by the data if correct this would imply that geodetically determined strain rates may be used as a proxy for potential seismic moment release in seismic hazard analyses for this region

late holocene evolution of the east eliki fault gulf of corinth central greece abstract trench stratigraphy and morphotectonic analysis was used to examine the recent evolution of the helike eliki plain and eliki fault the entire alluvial plain of the kerynites and vouraikos rivers which cross the eliki fault has subsided at rate of 1 4 mm yr resulting in the burial of the late hellenistic roman occupation horizons under 3 m of fluvial and colluvial sediments along the eastern segment of the eliki fault five trenches have been excavated and their 5000 yr old fluvial and colluvial deposits have been studied in association with the fault strand imprinted on them the kerynites river crosses at high angle the eliki fault and appears to be sensitive in tectonic movements related with the eliki fault sedimentation in the alluvial plain and the fluvial geomorphology of the kerynites river is important for understanding the fault evolution and the burial of the ancient 4th century bc helike city the kerynites river course highlights breaching deformation is the more likely to connect east and west eliki fault segments and that postseismic deformation is a significant mechanism for stress accommodation for part of the west end of the gulf of corinth

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

a late holocene record of environmental changes from the aliki lagoon egion north peloponnesus greece abstract aliki lagoon is a small lagoon located on the micro tidal south coast of the gulf of corinth greece the sediments of the lagoon recovered in three cores provide a record of late holocene environmental change including tectonic subsidence tsunami layers and change in local vegetation and sedimentation four periods of rapid environmental changes were identified over a 5000 yr long record these date from about 4700 3000 2500 and 2000 yr bp each change is linked to activity on the egion fault a deepening of the lagoonal bottom and a rise in relative sea level six tsunami events are recorded and have been caused by earthquakes on the egion fault three events 4700 3000 and 2500 bp eliki fault 2350 40 yr bp and two more distal fault ruptures the vegetation history and pollen zones are similar to those recognised by jahns vegetation hist archaebot 2 1993 187 on the argive plain 100 km southeast of the lagoon five successive sedimentological configurations are established in relation to the time frame provided by the tectonic activity 1 crevasse splay 2 fresh to brackish water marsh 3 and 4 brackish to hypersaline blind lagoon and 5 brackish to hypersaline blind lagoon or brackish open lagoon

new insights into the uplifted roman harbour at mavra litharia n peloponnese greece in the geodynamic context of the southern margin of the corinth gulf abstract recent archaeological excavations at mavra litharia in the area of aigeira n peloponnese have brought to light the eastern landward extension of a jetty the erosion of the cliff along the modern coast and the excavations at the inner side of the northern coastal section of the jetty provided a clearer picture of its structure significantly different than this presented in previous studies the harbour installations are assigned to between the 2nd century and the first half of the 3rd century ad according to the study of the structure the mobile findings and the epigraphic data biomarkers attached to the structure define the sea level during its operation and demonstrate the current uplift position the observed damage that has sustained the structure of the ancient jetty suggests that its destruction was co seismic and reveals the direction of seismic waves from the west reconstruction of the displaced blocks of the jetty in their original position archaeological interpretation and dating of the structure biomarker information and glacio isostatic modelling determine the sea level since the function of the harbour and the uplift of the ancient jetty as 5 35 0 37 m the age of the biological indicators 1686 cal p 264 ad is consistent with archaeological dating and the period of the sudden abandonment of the under reconstruction nearby theatre of ancient aigeira mid 3rd century ad the uplift of the roman harbour occurred at least in two phases initially by 4 35 m around 1686 bp and subsequently by 1 0 m around 657 bp the mean tectonic uplift rate of 2 81 0 20 mm yr for the coast in mavra litharia similar to these for the entire western part of the south shore of the corinth gulf is higher than the mean uplift rate of 1 21 0 28 mm yr in the easternmost edge the westernmost edge at the rio antirio strait presents very high subsidence rate of 5 17 0 47 mm yr

geodetic estimate of seismic hazard in the gulf of korinthos the recent 15 june 1995 m0 6 0 1018 n m aigion earthquake in the western gulf of korinthos has focussed attention on the seismic hazard of the region although there have been few large earthquakes in the region during this century the historical record suggests that there may have been many large earthquakes there in the interval 1750 1900 we present geodetic data that give estimates of the rate of extension of the gulf of korinthos during this century and which suggest that less than half of the elastic strain in the central and western gulf of korinthos has been released by earthquakes during this century in contrast the seismic and geodetic strains in the eastern gulf of korinthos are in agreement with each other if the discrepancy between seismic and geodetic strains in the western gulf of korinthos that has accumulated during this century is removed in earthquakes the moment release will be equivalent to several ms 6 5 earthquakes

a holocene coral algal reef at mavra litharia gulf of corinth greece structure history and applications in relative sea level change a holocene coral algal reef at mavra litharia south central coast of gulf of corinth greece is exposed from ca 2 to 9 3 m above sea level on an uplifting footwall associated with the eliki fault the reef lacks sea level critical species but its coralline algal assemblage indicates a ca 10 m water depth reef frame components date from 9280 8730 years bp to 6343 5993 years bp so the reef frame grew between ca 10 000 and 6000 years bp the youngest dated shells 1860 305 years bp from the site are accessory organisms collected from the lowest 2 m of outcrop one of which dendropoma grew at sea level stiros s c and pirazzoli p 1998 late quaternary coastal changes in the gulf of corinth greece tectonics earthquake archaeology guidebook for the gulf of corinth field trip patras university greece patras september 14 16 1998 reef history has four phases a growth and lithification of reef b development of smooth walled dissolution pipes and caves in the reef c colonisation of dissolution surfaces by mn fe crusts that may be bacterially formed barnacles serpulid worms and rock boring bivalves and d uplift to present position where much of the reef is eroded sea level history after 11 500 years bp when rising post glacial sea level overtopped the rio sill and returned the gulf of corinth to a marine environment is reconstructed calculations of interplay between sea level rise and tectonic uplift suggest that between 11 500 and 10 000 years bp sea level rose very quickly associated with deglaciation at the close of the younger dryas mwp 1b at a maximum of 25 6 mm year broadly consistent with other studies then slowed to ca 4 4 mm year until 6000 years bp when sea level was ca 3 m below modern after which sea level rose at ca 0 5 mm year to modern day tectonic uplift rate of maximum 3 mm year slower than sea level rise means that the reef could not catch up to sea level until recent times explaining its fossil assemblage the pipe cave system is interpreted as having formed when the reef top was emerged but much dissolution occurred beneath sea level because of insufficient time to allow uplift and resubmergence intense rainfall during the mid holocene pluvial phase ca 6000 years bp for the eastern mediterranean which affected large areas of the mediterranean is suggested as the mechanism and timing of submarine dissolution

new evidence for the geological origins of the ancient delphic oracle greece ancient tradition linked the delphic oracle in greece to specific geological phenomena including a fissure in the bedrock intoxicating gaseous emissions and a spring despite testimony by ancient authors many modern scholars have dismissed these traditional accounts as mistaken or fraudulent this paper presents the results of an interdisciplinary study that has succeeded in locating young faults at the oracle site and has also identified the prophetic vapor as an emission of light hydrocarbon gases generated in the underlying strata of bituminous limestone

geodetic determination of tectonic deformation in central greece from 1900 to 1988 the global positioning system has been used to measure the relative displacements of fifteen monuments in a hundred year old triangulation network spanning part of the aegean extensional basin these displacements reflect the tectonic deformation of the region over the past century showing more than one metre of north south extension across the network the crust in this region appears to contain a few slowly deforming blocks separated by more rapidly deforming zones

seismicity and associated strain of central greece between 1890 and 1988 summary we examined the seismicity of central greece between 1890 and 1988 using macroseismic and instrumental data to ask two questions 1 does the seismicity of this period reveal all the major tectonic structures that are known to be active and 2 what are the likely strains associated with the seismicity over this period many known active structures have been effectively aseismic for the last hundred years and even the inclusion of all known large events earlier than 1890 reveals no activity associated with the ne coast of evia gulf of argos or graben ne of mt parnassos it is clear that even 100 years data are inadequate for either a reasonable assessment of seismic risk or for a confident estimation of maximum magnitude however we are aware of no earthquakes in central greece during the last 200 yr that were larger than ms 7 0 it is probable that the maximum magnitude is restricted by the maximum length of fault segments which appears to be around 15 20 km the earthquakes of ms 5 8 during 1890 1988 can account for a n s displacement of around 45 70 cm with maximum and minimum estimates a factor of two greater and smaller than this across part of a 1890 1900 triangulation network in central greece that was resurveyed in 1988 the contribution of smaller events may increase this displacement by about 50 per cent this cumulative seismic displacement is similar to that estimated from the geodetic work about 100 cm but a detailed comparison of the two sets of observations will be reported elsewhere a re evaluation of all the important earthquakes of 1890 1988 in central greece is presented in the appendix which summarizes information of use to both earth scientists and engineers

dating recent colluvial sequences with 210pb and 137cs along an active fault scarp the eliki fault gulf of corinth greece reliable dating is an essential element of palaeoseismological studies yet whilst a suite of geochronological methods can now provide late quaternary age control it remains very difficult to date modern events i e those occurring within the last 150 years this is significant because the starting point for many palaeoseismological investigations is a modern surface rupturing event whose geological effects need to be disentangled in trench stratigraphies from palaeoseismic ruptures two dating methods which in combination can provide robust dating control in recently deposited sediments are the 210pb and 137cs dating methods here we test the applicability of using 210pb and 137cs to date colluvial sediments exposed in three trenches excavated across an earthquake fault the eliki fault gulf of corinth greece which ruptured in an earthquake in 1861 the 210pb and 137cs profiles observed in these colluvial sequences are relatively erratic due to the mixed nature of the sediments i e their deposition in an environment where the supply of slope sediments is driven by seasonal rainfall causing non uniform sediment accretion and sediment reworking in one trench however 210pb dating corroborated by 137cs dating indicates that a proposed post 1861 surface colluvial unit has been deposited over the period 1950 ad present at a rate of ca 9 mm year and overlies a significantly older unit 120 years old the dating control provided here by 210pb and 137cs dating corroborates the published interpretation of the trench stratigraphy and refines the 14c based estimated dates for the upper unit at two other trenches 210pb and 137cs dating only provided minimum ages based on the presence or absence of 210pbexcess and 137cs such approximate ages however may still useful in corroborating interpretations made using the trench stratigraphy or at sites which have long earthquake recurrence intervals determining which earthquake event was responsible for a particular bed offset

macroscopic seismic anomalies and submarine pockmarks in the corinth patras rift greece prior to the aigion earthquake m 6 2 of 15 june 1995 in the western gulf of corinth people in the area observed anomalous phenomena including bubbling of the sea extraordinary behavior of animals earthquake lights ground deformation and the sound of wind immediately before the shock some precursory phenomena of this kind might be understood as symptoms of gas venting before an earthquake sonar observations made in 1988 showed a chain of submarine pockmarks tracing the aigion fault and evidently produced by the expulsion of fluids under pressure t hasiotis et al mar geol 130 333 344 reported that hot gas erupted from a field of giant submarine pockmarks in the neighboring bay of patras several hours prior to an earthquake in 1993 automated monitoring of bottom water temperature in submarine pockmark fields may detect outgassing events prior to earthquakes in this region

episodic uplift deduced from holocene shorelines in the perachora peninsula corinth area greece four raised shorelines between 1 1 m and 3 5 m have been identified at two localities on the perachora peninsula and were dated by ams 14c to between 6400 and 1500 calibrated years ago uplift movements seem to have occurred in increments of 0 8 0 3 m with a return period of about 1600 years the last uplift coincided with a regional tectonic paroxysm which has already been documented in several areas of the eastern mediterranean the average uplift rate was probably faster during the holocene than the average since the last interglacial period no important vertical displacement occurred in this area at the time of or after the 1981 earthquake but a new episode of coseismic uplift may be in preparation

active faulting at delphi greece seismotectonic remarks and a hypothesis for the geologic environment of a myth historical data are fundamental to the understanding of the seismic history of an area at the same time knowledge of the active tectonic processes allows us to understand how earthquakes have been perceived by past cultures delphi is one of the principal archaeological sites of greece the main oracle of apollo it was by far the most venerated oracle of the greek ancient world according to tradition the mantic proprieties of the oracle were obtained from an open chasm in the earth delphi is directly above one of the main antithetic active faults of the gulf of corinth rift which bounds mount parnassus to the south the geometry of the fault and slip parallel lineations on the main fault plane indicate normal movement with minor right lateral slip component combining tectonic data archaeological evidence historical sources and a reexamination of myths it appears that the helice earthquake of 373 b c ruptured not only the master fault of the gulf of corinth rift at helice but also the antithetic fault at delphi similarly to the corinth earthquake of 1981 moreover the presence of an active fault directly below the temples of the oldest sanctuary suggests that the mythological oracular chasm might well have been an ancient tectonic surface rupture