self similarity properties of seismicity in the southern aegean area we investigate the time self similarity properties of seismicity in the hellenic are which is one of the most rapidly deforming and seismically active regions of the mediterranean area the presence of time scale invariance properties in the shallow and intermediate depth seismicity is revealed in particular 1 f beta fluctuations are detected from the analysis of earthquake sequences using the counting statistics methodology the shallow seismicity is characterized by a time clustering effect and shows a beta value that is a typical fingerprint of self similar behaviours whereas the intermediate seismicity can be considered as a realization of a purely poissonian process the investigations cover instrumentally recorded earthquakes occurring between 1964 and 1996 and the analyses have been carried out selecting different magnitude thresholds the beta value for shallow seismicity decreases from almost 0 5 to 0 2 as the threshold magnitude increases from 3 3 to 4 5 c 2000 elsevier science b v all rights reserved

seismicity of the aegean and surrounding area abstract seismicity parameters based on instrumental and historical data are given for 36 seismic sources of shallow earthquakes and for 6 seismic sources of intermediate depth earthquakes in the aegean and surrounding area 34 n 43 n 18 e 30 e these parameters are of two categories parameters of the first category are useful for seismic hazard evaluation a and b values of the frequency magnitude relation maximum earthquake magnitude number of shocks larger than certain magnitude per year while parameters of the second category are proper for describing the spatial distribution of seismicity mean return period most probable magnitude in a certain time period moment rate shallow seismicity is highest along the convex side of the hellenic arc but close to the coast ionian islands south peloponnesus south of crete south of karpathos and rhodos in central greece patraikos corinthiakos evoikos gulfs thessalia and along a seismic belt which includes the northwestern anatolia fault zone the northernmost part of the aegean sea and the serbomacedonia zone the intermediate depth seismic activity is distributed in two parts of the benioff zone which dips from the convex side eastern mediterranean to the concave side aegean sea of the hellenic arc the one part shows a low dip angle and includes earthquakes with focal depths between 70 km and 100 km this part has a high seismicity earthquake magnitudes up to 8 0 and is situated below the inner slope of the sedimentary part of the hellenic arc eastern peloponnesus north of crete rhodos based on the fact that this part of the benioff zone is a continuation of the seismic zone of shallow earthquakes along the hellenic arc and that both zones have the same seismicity it is concluded that they constitute a continuous seismic belt on which coupling occurs between the subducted eastern mediterranean lithosphere and the overthrusted aegean lithosphere the other inner part of the benioff zone shows low seismicity maximum earthquake magnitude up to 7 1 with earthquakes of focal depths between 100 km and 180 km it dips at a mean angle of 38 below the volcanic arc of the southern aegean sea and is the result of the subduction of the front part of the eastern mediterranean lithosphere without coupling with the aegean lithosphere

crustal strain in central greece from repeated gps measurements in the interval 1989 1997 summary a 66 station gps network spanning central greece first observed in 1989 has been occupied fully on three occasions june 1989 october 1991 and may 1993 subsets of this network bounding the gulf of korinthos have also been occupied in june 1995 october 1995 may 1996 and september october 1997 the first three occupations were processed using a fiducial gps methodology whereas later surveys were processed using code precise orbits combination of data from different surveys to yield smooth site velocities requires global network translations at each epoch to compensate for errors in the realization of the reference frame this method provides a posteriori estimates of the relative coordinate errors and reference frame noise only one earthquake the 1995 june 15 egion event has caused significant local coseismic displacement and its effects on the interseismic velocity field are removed using an elastic dislocation model we constrain the orientation of the 100 yr triangulation gps velocity estimates of davies et al 1997 using 14 sites common to the two networks the goodness of fit of this transformation indicates that the short term and 100 yr geodetic estimates of deformation are highly compatible we infer that short term geodetic studies are capable of determining longer term deformation rates provided that transient local effects can be modelled from the combined velocity field we estimate principal strains and rigid body rotation rates at points on a regular grid using data from neighbouring sites strain rates are high within the gulf of korinthos and much lower elsewhere the extension rate across the gulf of korinthos increases from east to west comparison of the extension rate with historical and recent rates of seismic release of strain reveals significant medium term seismic hazard in the western gulf of korinthos and may also indicate long term aseismic strain

rates of crustal deformation in western turkey as deduced from major earthquakes abstract western turkey has undergone dominantly n s extension probably since the late miocene this extensional regime caused the formation of e w trending grabens and similarly orientated normal faults the rates of deformation of the seismogenic layer caused by the major earthquakes ms 5 5 during the period between 1943 and 1983 are calculated for western anatolia this region is first analysed as a single system and then divided into two provinces namely the marmara and southwestern anatolian provinces which are investigated as two separate seismotectonic units the dominant mode of deformation in the marmara province is amounting to right lateral displacement 24 0 mm yr other modes of upper crustal deformation in this province can be explained by an average 7 1 mm yr n s extension 10 0 mm yr e w contraction and 0 13 mm yr thinning of a 10 km seismogenic layer the dominant mode of deformation in southwestern anatolia is about 13 5 mm yr extension in the n s direction this region is also undergoing e w extension of about 3 6 mm yr justifying the separation of marmara and southwestern anatolian provinces as two different seismotectonic provinces the average rate of thinning of the seismogenic layer in this area is 0 5 mm yr which is consistent with large scale normal faulting observed here it is found that n s extension in western anatolia increases from north to south while e w compression in the marmara province changes to e w extension in southwestern anatolia it is suggested that these kinematics may explain the present bending of the north anatolian transform forming a transtensional basin between the marmara and southwestern anatolian provinces

evidence for transform faulting in the ionian sea the cephalonia island earthquake sequence of 1983 accurate locations of aftershocks of the january 17 1983 ms 7 0 main shock in the ionian islands have been determined as well as fault plane solutions for this main shock and its largest aftershock which are interpreted as a right lateral strike slip motion with a thrust component on a fault striking in about a ne sw direction

geology a trip to dinosaur time a project to drill a 10 kilometre deep hole in china will provide the best view yet of the turbulent cretaceous period jane qiu reports

local seismic array observations at north evoikos central greece delineate crustal deformation between the north aegean trough and corinthiakos rift abstract in order to better constrain and define the microseismic activity at the north evoikos gulf and its surrounding area we deployed an onshore offshore seismic array consisting of 31 three component seismic digital stations the array was active from 30 june to 24 october 2003 and covered an area of 2500 km 2 we located more than 2000 seismic events ranging from 0 7 to 4 5 m l by using six stations as a minimum in order to define the foci parameters recorded seismicity delineated three major zones of deformation from south to north the eretria parnis eastern corinthiakos zone the psachna viotia zone and the northern sporades north evia bralos zone alignments of the recorded seismicity follow the tectonic trends and their orientation in the above zones the whole area accommodates the stress field between the north aegean trough and the corinthiakos gulf rate of deformation intensifies from north to south as revealed also by historical and instrumental seismicity the successive change of orientation between the two stress fields fragments the crust in relatively small units and the fault systems developed do not permit the generation of major earthquakes in the north evoikos area and its immediate vicinity this is also supported by the instrumental seismicity of the last century larger events reported in historical times are probably overestimated most seismic activity is crustal subcrustal events were recorded mainly below the lichades area and are interpreted as the consequence of the subduction of the ionian oceanic lithosphere below the hellenides the lichades volcano is the most northern end of the hellenic volcanic arc at present the highest seismic activity is associated with the psachna region of north evia that has been continuously active since 2001 considering however the development of the seismic activity during the last decade there has been a sequence of large events i e parnis in 1999 skyros in 2001 and psachna in 2001 2003 this demonstrates the fact that the tectonic deformation in all this area is intense and important for the accommodation of the stress field of the north aegean trough to that of the corinthiakos rift

circulations associated with a mature to decaying midlatitude mesoscale convective system part i surface features heat bursts and mesolow development abstract this study examines surface features associated with a mature to dissipating midlatitude mesoscale convective system that occurred on 23 24 june 1985 during the oklahoma kansas preliminary regional experiment for storm central the primary data sources include a 400 500 km surface mesonetwork on a 50 km grid rawinsonde observations from 12 supplementary sites in kansas and oklahoma and radar measurements from conventional as well as dual doppler networks the mesoscale convective system under investigation developed in an environment with weak vertical shear and had a lifetime of 9 12 h it consisted in its mature stage of a southward moving arc shaped line of deep convective cells with a trailing stratiform precipitation region to the north thirty three percent of the surface rain in the portion of the mesonetwork experiencing storm passage was from the stratiform region an intense mesoscale downdraft developed beneath the stratiform cloud with a strong mesohigh at the surface a wake low w

the chicxulub asteroid impact and mass extinction at the cretaceous paleogene boundary the cretaceous paleogene boundary similar to 65 5 million years ago marks one of the three largest mass extinctions in the past 500 million years the extinction event coincided with a large asteroid impact at chicxulub mexico and occurred within the time of deccan flood basalt volcanism in india here we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction notably a single ejecta rich deposit compositionally linked to the chicxulub impact is globally distributed at the cretaceous paleogene boundary the temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations for example darkness and cooling lead us to conclude that the chicxulub impact triggered the mass extinction

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

s wave attenuation in the crust in northern greece abstract the attenuation of shear waves in the crust is estimated for frequencies between 1 5 and 12 0 hz by applying a single station method based on the rate of decay of the s wave to coda wave amplitude ratio with distance the data used come from local earthquakes that occurred in the thessaloniki area northern greece during the period 1983 through 1989 and were recorded by the telemetered network of the geophysical laboratory of the university of thessaloniki the q s values obtained are 115 244 477 and 755 for 1 5 3 0 6 0 and 12 0 hz respectively these values are very close to the coda q values estimated for the same area using the s to s single scattering model for lapse times between 30 and 100 sec but they are higher than the coda q values for lapse times between 10 and 30 sec the estimated q s is found to be strongly frequency dependent proportional to f 0 91 which is very close to the frequency dependence of the coda q

anisotropic radiation modelling of macroseismic intensities for estimation of the attenuation structure of the upper crust in greece a method is suggested for the analysis of macroseismic intensity data in order to accurately determine an average attenuation structure of the upper part of the crust in an area the method is based on a model which assumes that the observed intensities depend on source properties radiation pattern size focal depth geometrical spreading and anelastic attenuation the method is applied to 13 008 intensity values observed in corresponding sites of greece and grouped in 4228 groups according to their spatial clustering in order to diminish observational errors and site effects an average intensity attenuation coefficient c 0 0039 0 0016 corresponding to a quality factor q 350 140 is determined for the upper 20 km of the crust in this area this value is relatively low in good agreement with the relatively high heat flow and high seismic activity of this area a byproduct of the present study is the determination for each earthquake of a macroseismic focal depth and of a macroseismic size which is strongly correlatted with both the earthquake s magnitude and its seismic moment determined by independent methods

seismicity in the hellenic volcanic arc relation between seismic parameters and the geophysical fields in the region summary a study of the spatial distribution of seismicity and seismic hazard and geophysical parameters is undertaken along the hellenic volcanic arc hva seismicity of the area is divided in a cellular manner allowing analysis of the localized seismicity parameters and representation of their regional variation as contour maps extreme value analysis locates a zone of highest seismicity just west of centre of the hva around the cyclades islands non probabilistic modelling of the strain energy release process in terms of magnitudes equivalent to the average annual energy release rate m and the maximum possible energy release in a seismic cycle m3 enhances this picture maximum values of m and m3 are more tightly localized in the central cyclades west of amorgos island and also in the east of the hva in the sporadhes north west of rhodes isocyclic contours of the waiting times for m3 show values in excess of 70 years in the cyclades and eastern sporadhes i e the zones of largest earthquakes show the longest strain accumulation periods the waiting time for the hva as a whole is about 54 years and at present it appears to be about 75 per cent through to accumulation of the notional maximum strain energy the b value of the magnitude frequency distribution shows a consistent spatial variation along the hva which is not sensitive to subdivision into different focal depth ranges regional contour maps of the b values and maps of local values of heat flow magnetic and electrical anomalies compared with the bouguer gravity anomaly map indicate correlations which reflect the deformation of the aegean shallow crust in relation to the deep intrusive magmatic processes the correlations between the different geophysical fields are displaced commensurate with an aegean extension of approximately 45 km

unified local magnitude scale for earthquakes of south balkan area a homogeneous earthquake catalog spanning 1964 1995 for the southern balkan area is presented by expressing the size of the earthquakes in a unified local magnitude scale the strategy followed to produce this catalog is also presented local magnitudes calculated by six balkan seismological centers ath the isk tir ttg sko have been used in order to obtain relations between the estimated m l values from the greek seismological centers ath and the and the remaining four balkan stations since it was found that local magnitudes estimated by ath and the are almost identical they have been used as one data set so as to correlate with the data of each one of the remaining four seismological stations based on the proposed relations a unified local magnitude m lgr is given for each earthquake of the regional catalog a published scaling relation between the m l values from ath and the networks and the corresponding seismic moment magnitude m w was used in combination with the above relations in order to enable the conversion of any m l value from any station into m w the catalog completeness has been checked and the b value has been calculated for the complete data sample

accelerating seismic crustal deformation in the southern aegean area a region of intense accelerating seismic crustal deformation has been identified in the southwestern part of the hellenic arc broader area of cythera island the identification is performed using a detailed parametric grid search of the broader southern aegean area for accelerating energy release behavior the identified region has similar properties with past preshock critical regions which have been identified for strong mainshocks in the aegean area based on such observations which suggest that this region is at a critical state that can lead to a critical point that is to the generation of a mainshock an estimation is made of the possible epicenter coordinates magnitude and origin time of this oncoming large m 7 0 earthquake the estimation procedure is validated on the basis of retrospective analysis of strong events in the aegean area as well as by appropriate application on synthetic random catalogs these results the existence of similar observations of accelerating seismic deformation in eastern part of southern aegean and independent information on the time distribution of large earthquakes m 6 8 for the whole southern aegean indicate that the generation of strong earthquakes in this area in the next few years must be considered as very probable

p and s deep velocity structure of the hellenic area obtained by robust nonlinear inversion of travel times we derived a new model for the p and s velocity structure of the lithosphere in the subduction area of the hellenic arc and the aegean sea from the inversion of travel times of local events the inversion technique applied is nonlinear since three dimensional ray tracing is incorporated at the same time an appropriate preconditioning of the final linearized system is used in order to reduce ray density effects on the results the p s coherency is controlled by an additional damping of the vp vs ratio the study focuses mainly on the structure of the hellenic subduction in the southern aegean region interesting features and details of the subducted slab can be recognized in the final tomographic images on the western part the shallower section of the slab is dipping at a very small angle 10 this changes to approximately 25 for the deeper part of the subduction resulting in a prominent kink at a depth of about 70 km which is in accordance with the general characteristics of the associated benioff zone the smaller eastern part of the slab is not resolved with the same detail but a clearly steeper subduction zone can be recognized moreover detailed information about the crustal thickness variations are inferred from the velocity structure and correlate very well with the existing results from refraction experiments finally the results confirm the recent suggestion concerning the existence of a low velocity crustal layer at shallow depths 10 15 km in the accretionary prism of the alpine belt

vertical displacement trends in the aegean coastal zone ne mediterranean during the holocene assessed by geo archaeological data trends in the vertical displacement i e uplift or subsidence of the aegean sea coastal zone have been assessed by comparing observational data with those derived from the predictive glacio hydro isostatic model of lambeck and purcell 2005 for a period spanning from the mesolithic to the late roman times the data base comprises published studies that use both geomorphological with associated biological material and archaeological sea level indicators markers localities demonstrating uplift of high amplitude were detected in front of the hellenic arc antikythira crete rhodes nisyros and in the northeast aegean region thrace whilst areas experiencing tectonic subsidence were mainly observed in the central aegean region which is characterized by an extensional tectonic domain however regional scale tectonic particularities have caused uplift in parts of the west and east coast of central aegean tectonically stable sites can be found in the cyclades plateau however this is due to a bala

ground motion prediction equations of intermediate depth earthquakes in the hellenic arc southern aegean subduction area a response spectra database is compiled of hundreds of seismic records from intermediate depth earthquakes earthquakes whose foci are located between 45 to 300 km from the earth s surface with moment magnitudes of m 4 5 6 7 that occurred in the south aegean subduction zone the database consists of high quality data from both acceleration sensor and broadband velocity sensor instruments the database is much larger than previous databases used in the development of past em pirical regressions enabling the determination of various parameters of ground motion attenuation not previously examined new variables accounting for the highly com plex propagation of seismic waves in the greek subduction zone are introduced based on the hypocentral depth and the location of the event as these factors control the effects of the back arc low velocity low q mantle wedge on the seismic wave propa gation the derived results show a strong dependence of the recorded ground motions on both hypocentral depth and distance which leads to the classification of the dataset into three depth hypocentral distance categories ground motions from in slab earth quakes especially with hypocentral depthsh 100 km are amplified for along arc stations an expected effect of channeled waves through the high velocity slab the ground motions are also strongly attenuated in the back arc region due to the low q mantle wedge which are almost independent of the recording hypocentral distance in contrast for shallower in slab events 60 km h 100 km the corresponding dif ferentiation of seismic motion for along arc and back arc stations is observed beyond a specific critical distance range moreover for longer periods both along arc ampli fication and back arc anelastic attenuation factors strongly diminish suggesting that the longer wavelengths of seismic waves are not affected by the complex geophysical structure resulting in more similar ground motions for both back arc and along arc stations finally results for interface events h 45 km occurring along the outer hellenic arc suggest their wave propagation is not affected by the presence of the low velocity low qs mantle wedge but is mainly controlled by the differences of the anelastic attenuation between the mediterranean and aegean lithospheres

evidence of nonextensive statistical physics behavior of the hellenic subduction zone seismicity abstract the hellenic subduction zone hsz is the most seismically active region in europe many destructive earthquakes have taken place along the hsz in the past in this study we investigate the seismicity of the hsz based on the science of complex systems the spatiotemporal distributions of seismicity as well as the magnitude distribution are studied using the concept of nonextensive statistical physics nesp defining five seismic zones and forming an earthquake dataset that covers the period 1976 2009 we apply the nesp ideas to formulate the cumulative distribution functions of the inter event times and distances and the magnitude distribution along the hsz our results indicate that the nonextensive parameter qt which is related with the inter event time distribution presents almost similar values in each of the seismic zones and reflects the long term scale of the seismicity evolution in the hsz the qd parameter which is related with the inter event distance distribution presents a significant variation along the seismic zones this variation is related with the different degree of spatial earthquake clustering in each of the seismic zones of the hsz moreover in the framework of the fragment asperity model the thermostatistical parameter qm which is related with the frequency magnitude distribution could be used as an additional index to inform us about the physical state of each seismic zone along the hsz the variations of the qm parameter are related with the energy release rate in each seismic zone the models used fit rather well to the observed distributions implying the usefulness of nesp in investigating such phenomena exhibiting scale free nature and long range memory effects

coseismic crustal deformation from microseismicity in the patras area western greece summary the patras area lies in the western part of central greece it is an area characterized by high seismicity and complex neotectonics several devastating earthquakes have occurred in the region since 600 bc contemporary crustal deformation is examined in this area using microearthquake data recorded over a lengthy period during 1983 84 by the patras seismic network principally and to a lesser extent by the volos seismic network the microseismicity 1 8 3 9 ml defines a zone deepening to the ne which justifies a possible extension of the gulf of corinth major graben towards the trikhonis lake to the nw spectra of 108 well located microearthquakes are estimated using p waves obtained by selective windowing designed to include only the p phase seismic moments in the range 0 3 45 7 1012 nm are obtained accompanied by estimates of seismotectonic source parameters including source radii average stress drop and average coseismic slip poor correlation is found between seismic moment and magnitude and the likely reason is the complex nature of the neotectonic regime existing in the area two zones differing in crustal deformation characteristics are observed the corinth trikhonis zone reveals two sets of characteristic faults the first set is represented by microearthquakes showing distinctive and relatively higher seismic moments in conjunction with lower stress drops and seismic slips this set of faults shows greater source radius than the second set and therefore the faults are longer the second set is characterized by an almost constant source radius within the range of uncertainty and a wide range of seismic moments stress drops and seismic slips the rio zone is characterized by low seismic slip stress drop and fault radii with the exception of the locality south of the city of patras where relatively higher seismic slip stress drop and fault radius are observed

a dwarf elephant and a rock mouse on naxos cyclades greece with a revision of the palaeozoogeography of the cycladic islands greece during the pleistocene abstract during the late pleistocene naxos and adjacent areas including delos and paros constituted a mega island here referred to as palaeo cyclades the extensive low lying plains with lakes and rivers provided a suitable habitat for elephants due to long term isolation from the mainland and mainland populations these elephants evolved miniature size the species found on naxos had a body size of about ten percent of that of the mainland ancestor palaeoloxodon antiquus during the glacial periods of the late pleistocene p antiquus may have migrated eastwards and southwards in search of better conditions and reached the islands the dwarf species of the various southern aegean islands e g crete tilos rhodos palaeo cyclades are each the result of independent colonisation events the very small size of the naxos species respective to the dwarf elephants from crete is explained as due to the lack of competitors the only other elements of the contemporaneous fauna were a rock mouse apodemus cf mystacinus and a shrew crocidura sp submergence of the area climate change volcanism hunting by humans or a combination of these factors during the terminal pleistocene may have caused the extinction of this endemic fauna

a deterministic seismic hazard analysis for shallow earthquakes in greece abstract the maximum expected ground motion in greece is estimated for shallow earthquakes using a deterministic seismic hazard analysis dsha in order to accomplish this analysis the input data include an homogeneous catalogue of earthquakes for the period 426 bc 2003 a seismogenic source model with representative focal mechanisms and a set of velocity models because of the discrete character of the earthquake catalogue and of errors in location of single seismic events a smoothing algorithm is applied to the catalogue of the main shocks to get a spatially smoothed distribution of magnitude based on the selected input parameters synthetic seismograms for an upper frequency content of 1 hz are computed on a grid of 0 2 0 2 the resultant horizontal components for displacement velocity acceleration and dga design ground acceleration are mapped the maps which depict these results cannot be compared with previously published maps based on probabilistic methodologies as the latter were compiled for a mean return period of 476 years therefore in order to validate our deterministic analysis the final results are compared with pga estimated from the maximum observed macroseismic intensity in greece during the period 426 bc 2003 since the results are obtained for point sources with the frequency content scaled with moment magnitude some sensitivity tests are performed to assess the influence of the finite extent of fault related to large events sensitivity tests are also performed to investigate the changes in the peak ground motion quantities when varying the crustal velocity models in some seismogenic areas the ratios and the relative differences between the results obtained using different models are mapped and their mean value computed the results highlight the importance in the deterministic approach of using good and reliable velocity models

the seismic parameter b of the frequency magnitude relation and its association with the geological zones in the area of greece abstract the parameter b of the frequency magnitude relation has been accurately calculated for each of the 21 seismic zones into which the aegean and surrounding area 34 n 43 n 18 e 30 e has been divided on the basis of several seismotectonic criteria these 21 seismic zones have been geographically separated into three a b c groups regions according to the values of the parameter b the outer region a is characterized by a relatively high value 1 03 the middle region b by an intermediate value 0 84 and the innermost region c by a low value 0 60 the boundaries of these three groups of zones almost coincide with the boundaries of well known geological zones this observation is interpreted in terms of mechanical heterogeneity of the material and of structural and stress conditions in the area

earthquake scenario based tsunami wave heights in the eastern mediterranean and connected seas we identified a set of tsunami scenario input parameters in a 0 5 0 5 uniformly gridded area in the eastern mediterranean aegean both for shallow and intermediate depth earthquakes and black seas only shallow earthquakes and calculated tsunami scenarios using the swan joint research centre swan jrc code mader 2004 annunziato 2007 with 2 arcmin resolution bathymetry data for the range of 6 5 mwmax with an mw increment of 0 1 at each grid in order to realize a comprehensive analysis of tsunami wave heights from earthquakes originating in the region we defined characteristic earthquake source parameters from a compiled set of sources such as existing moment tensor catalogues and various reference studies together with the mwmax assigned in the literature where possible results from 2 415 scenarios show that in the eastern mediterranean and its connected seas aegean and black sea shallow earthquakes with mw 6 5 may result in coastal wave heights of 0 5 m whereas the same wave height would be expected only from intermediate depth earthquakes with mw 7 0 the distribution of maximum wave heights calculated indicate that tsunami wave heights up to 1 m could be expected in the northern aegean whereas in the black sea cyprus levantine coasts northern libya eastern sicily southern italy and western greece up to 3 m wave height could be possible crete the southern aegean and the area between northeast libya and alexandria egypt is prone to maximum tsunami wave heights of 3 m considering that calculations are performed at a minimum bathymetry depth of 20 m these wave heights may according to green s law be amplified by a factor of 2 at the coastline the study can provide a basis for detailed tsunami hazard studies in the region

a detailed study of the active crustal deformation in the aegean and surrounding area abstract a detailed study of the active crustal deformation in the aegean sea and surrounding area is presented the estimation of the deformation velocities is not performed in broad seismic zones but in seismogenic sources of limited spatial extent where the seismic energy is practically released in order to describe the spatial variations of the components of the strain rate tensor the deformation analysis is based on previous work where the seismicity and the available focal mechanisms are used separately for estimating the rate and shape of the deformation respectively the calculations were performed for 63 seismogenic sources identified in the aegean sea and surrounding area which belong to eight belts with an almost uniform orientation of the stress field along the coasts of albania and northwestern greece up to leukada island the collision of the adria plate with eurasia results in a compressional velocity of about 4 mm yr in a direction n49 e almost normal to the coast line the dextral movement with almost 3 cm yr along the cephalonia transform fault with strike n45 e is expressed as an almost equal extension and compression in n s and e w direction respectively along the convex outer part of the hellenic arc a crustal shortening of 1 3 cm yr is observed in a mean direction n34 e the direction of this shortening is almost constant from the southern ionian islands zakynthos up to rodos while the shortening rate does not significantly change from the outer sources to the inner ones the aegean sea and surrounding area is characterised by an extensional deformation the direction of the maximum extension in the northern part of this area shows an anticlockwise rotation from east to west thus this extension has a nne direction in northwestern turkey n11 e a nnw direction in central and northern greece as well as along the southern aegean volcanic arc and its extension to southwestern turkey n12 w and a wnw direction in the westernmost part of this extensional area n72 w the mean value of the extensional velocities in this area is 5 mm yr the northern part of asia minor and of the aegean sea is characterised by the dextral strike slip movement of about 2 cm yr of the north anatolian fault and its continuation in the northern aegean where this movement gradually decreases to about 6 mm yr the vertical crustal upper 10 km of the crust thickening is about 2 mm yr along the convex side of the hellenic arc and the vertical crustal thinning is about 1 mm yr in the aegean sea these values were obtained from the component u 33 of the velocity tensor

surface fault traces fault plane solution and spatial distribution of the aftershocks of the september 13 1986 earthquake of kalamata southern greece a shallow earthquake ofms 6 2 occurred in the southern part of the peloponnesus 12 km north of the port of the city of kalamata which caused considerable damage the fault plane solution of the main shock geological data and field observations as well as the distribution of foci of aftershocks indicate that the seismic fault is a listric normal one trending nne ssw and dipping to wnw the surface ruptures caused by the earthquake coincide with the trace of a neotectonic fault which is located 2 3 km east of the city of kalamata and which is related to the formation of messiniakos gulf during the pliocene quaternary tectonics field observations indicate that the earthquake is due to the reactivation of the same fault

seismic faults in the aegean area abstract reliable fault plane solutions of shallow earthquakes and information on surface fault traces in combination with other seismic geomorphological and geological information have been used to determine the orientation and other properties of the seismic faults in the aegean and surrounding area thrust faults having an about nw se strike occur in the outer seismic zone along western albania westernmost part of mainland of greece ionian sea south of crete south of rhodes the inner part of the area is dominated by strike slip and normal faulting strike slip with an about ne sw slip direction occurs in the inner part of the hellenic arc along the line peloponnesus cyclades dodecanese southwest turkey as well as along a zone which is associated with the northern aegean trough and the northwesternmost part of anatolia all other regions in the inner part of the area are characterized by normal faulting the slip direction of the normal faults has an about sw ne direction in crete n38 e and an about e w direction n81 e in a zone which trends n s in eastern albania and its extension to western mainland of greece in all other regions central greece southern yugoslavia and bulgaria western turkey the slip of the normal faults has an about n s direction

isotopic evidence for glaciation during the cretaceous supergreenhouse the turonian 93 5 to 89 3 million years ago was one of the warmest periods of the phanerozoic eon with tropical sea surface temperatures over 35 c high amplitude sea level changes and positive 18 o excursions in marine limestones suggest that glaciation events may have punctuated this episode of extreme warmth new 18 o data from the tropical atlantic show synchronous shifts 91 2 million years ago for both the surface and deep ocean that are consistent with an approximately 200 000 year period of glaciation with ice sheets of about half the size of the modern antarctic ice cap even the prevailing supergreenhouse climate was not a barrier to the formation of large ice sheets calling into question the common assumption that the poles were always ice free during past periods of intense global warming

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

precursory seismicity changes associated with the mw 7 4 1999 august 17 izmit turkey earthquake summary we investigated precursory seismicity in and around the epicentral zone of the mw 7 4 1999 august 17 izmit turkey earthquake by applying a statistical method the rtl region time length algorithm to earthquake catalogues derived from that for the period 1981 1999 of kandilli observatory and earthquake research institute koeri the derived catalogues are complete for events md 3 in most of western turkey after declustering aftershocks we investigated the seismicity patterns preceding the izmit event at local izmit tectonic zone and national turkey scales the rtl parameter indicates that a period of seismic quiescence started at the end of 1995 and reached a minimum in december 1996 an activation phase lasting about three months followed the main shock in izmit and vicinity did not occur when the seismicity returned to its background level but occurred with a delay of nearly 2 5 yr we present a new parameter to quantify the spatial distribution of seismic quiescence the results from both catalogues indicate that a significant quiescence anomaly appeared in 1996 around the epicenter of the izmit earthquake the primary characteristics of the seismicity patterns prior to the izmit earthquake are similar to those obtained for large events in russia and japan the variations of seismicity patterns revealed by the rtl algorithm may offer better understanding of the physical nature of seismo tectonics and provide useful information for seismic hazard estimation the varying characteristics of the izmit and other events may reflect the difference between seismo tectonics in turkey and in other regions such as russia and japan

paleogeographic conditions in the western pelagonian margin in greece during the initial rifting of the continental area the uppermost paleozoic metaclastic sequences of the pelagonian zone in northern greece are connected to the western margin of the zone they represent paleogeographic conditions of a deltaic environment and continental slope which are related to the separation of the paleozoic continent and the initial rifting in the western ophiolite belt in greece the metaclastic sequences define the western external boundary of the pelagonian zone and are used to find the continuation of this boundary in the sporades and oinouses islands in the aegean sea in order to help answer the question of the connection between the hellenides and the taurides in turkey

tomography of the crust and upper mantle in southeast europe compressional velocity structure of the crust and the upper mantle in southeastern europe broader aegean area is studied by inverting residuals of the first p arrivals from earthquakes in this region 16 e 31 e 34 n 43 n the data used are from regional events recorded by the permanent network of stations during the period 1971 1987 enriched with data from experiments with portable seismographs in four regions of this broad area this study confirms the strong variations of crustal thickness in this area as well as the subduction of the eastern mediterranean lithosphere under the southern aegean and gives further detailed information on the crustal and upper mantle structure of the area important new information is the existence of a low velocity crustal layer in western greece and albania and that the velocity anomaly in the mantle under the southern aegean extends much farther and deeper to the northeast than the benioff zone of the intermediate depth earthquakes indicates furthermore evidence is presented about the possible existence of older subduction in the northern aegean and about the influence of the tectonic regime on the velocity field

normal faults associated with volcanic activity arc abstract volcanic centers volcanoes fumaroles or solfatara fields epicenters of strong shallow earthquakes with focal depths up to 20 km and epicenters of intermediate depth strong earthquakes with focal depths between 120 and 160 km in the southern aegean volcanic arc can be grouped into five well defined linear clusters trending about n60 e this lineation of shallow earthquakes and volcanic activity is attributed to five corresponding normal faults which are named after the five corresponding volcanic centers sousaki methana milos santorini and nisyros this is supported by a similar trend of the geomorphological features grabens and islands and of geophysical features bouguer anomalies as well as by other seismological data fault plane solutions and the origins of tsunamis and geological information on the santorini caldera the greater volcanic activity in the eastern volcanic centers santorini and nysiros compared to the western volcanic centers sousaki methana and milos is attributed to the higher rate of extensional crustal deformation in the eastern part of the volcanic arc it is 26 mm yr in the west it is 2 mm yr the delineation of the epicenters of the intermediate depth earthquakes along the same five lines indicates the existence of five corresponding rupture zones in the lower leading part of the descending lithospheric slab at depths of 120 180 km these deep zones are probably the sources of hot material which is ascending vertically upwards and intrudes into the crust along its fracture zones the orientation of these zones explains the focusing of the macro seismic results of these deep shocks at narrow regions of the sedimentary arc peloponnesus crete etc

attenuation of coda waves in northern greece the single scattering model has been applied for the estimation of codaq values for local earthquakes that occurred in northern greece during the period 1983 1989 and recorded by the telemetered network of the geophysical laboratory of the university of thessaloniki codaq estimations were made for four frequency bands centered at 1 5 hz 3 0 hz 6 0 hz and 12 0 hz and for the lapse time windows 10 20 sec 15 30 sec 20 45 sec 30 60 sec and 50 100 sec the codaq values obtained show a clear frequency dependence of the formq c q 0 f n whileq 0 andn depend on the lapse time window q 0 was found equal to 33 andn equal to 1 01 for the time window of 10 to 20 sec while for the other windowsq 0 increased from 60 to 129 withn being stable close to 0 75 this lapse time dependence is interpreted as due to a depth dependent attenuation the high attenuation and the strong frequency dependence found are characteristic of an area with high seismicity in agreement with studies in other seismic regions

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

a numerical model of the hellenic subduction zone active stress field and sea level changes a 2 d viscoelastic finite element model for subduction in the southern aegean sea allows us to study the distribution of stress and surface velocities in a vertical cross section through the island of crete recent tomographic results constrain the geometry of the slab and the structure of the crust lithosphere and mantle two models are considered the first for passive subduction driven solely by slab pull and the second one where active convergence between the african and aegean plates is also included both models predict subsidence of the hellenic trench and of cretan trough uplift of crete and of the aegean volcanic arc the island of crete is subject to differential uplift highest in the southern part with maximum rates of 1 5 and of 3 2 mm yr for the two models respectively these results agree with the tectonic uplift inferred from holocene sea level changes in the island the style of stress within the modeled african and aegean plates is in general agreement with the focal mechanisms of the largest earthquakes along the subduction zone

rates of crustal deformation in the north aegean trough north anatolian fault deduced from seismicity the rates and configuration of seismic deformation in the north aegean trough north anatolian fault are determined from the moment tensor mechanisms of the earthquakes that occurred within this region the analysis is based onkostrov s 1974 formulation the fault plane solutions of the earthquakes of the period 1913 1983 withms 6 0 are used the focal mechanism of some of the past events before 1960 is assumed based on the present knowledge of the seismotectonics as well as on the macroseismic records of the area studied the analysis showed that the deformation of the northern aegean is dominated by ew contraction at a rate of about 15 mm yr which is relieved by ns extension at a rate of about 9 mm yr it was also shown that the northern part of north anatolia north of 39 7 n parallel undergoes contraction in the ew direction at a rate of about 9 mm yr and ns extension as the dominant mode of deformation at a rate of about 5 mm yr it may be stated therefore that the pattern of deformation of the northern aegean and the northern part of north anatolian fault is controlled by the ns extension the aegean is undergoing as a whole and the dextral strike slip motion of the north anatolian fault the southern part of north anatolia is undergoing crustal thinning at a rate of 2 3 mm yr ns extension at a rate of 5 mm yr as well as ew extension at a rate of 4 mm yr which are consistent with the occurrence of major normal faulting and justify the separation of north anatolia into two separate subareas

sea level rise trends in the attico cycladic region aegean sea during the last 5000 years abstract sea level change during the last 18 000 years is a combination of eustatic isostatic and tectonic contributions in an effort to minimize the tectonic contributions our study of sea level changes in the aegean sea within historical times is focused on the aseismic attico cycladic geotectonic zone on the basis of archaeological information and radiocarbon dating of coastal sedimentological formations a sea level curve for the attico cycladic massif has been constructed for the past 5000 years and compared with existing curves according to this curve the rapid increase of sea level concluded prior to 5 5 ka and was followed by a slow steady rise at a rate of 0 9 mm a up to its present stage the latter is attributed primarily to the process of thermal expansion and secondarily to the residual melting of the glaciers and existing ice caps by extrapolation of the curve the sea level at the end of the 20th century is predicted to be about 9 cm higher than the present level this value is much lower than the prediction of the last ipcc report 49 cm if higher slr rates are realised in the next few decades then the excess 40 cm of the ipcc prediction can be attributed to human induced global climatic change

development of a tsunami inundation map in detecting tsunami risk in gulf of fethiye turkey namidance tsunami simulation and visualization tool is used to create tsunami inundation maps showing quantitative maximum tsunami flow depths in fethiye the risk of an extreme but likely earthquake generated tsunami is estimated at fethiye bay for 14 probabilistic earthquake scenarios the bay is located 36 39 5 n 29 7 23 e southwestern turkey which has coastline to the eastern mediterranean sea the tsunami simulation and inundation assessment are performed in three stages 1 formation of a digital elevation model of the region from the best available topography bathymetry dataset 2 estimation of a maximum credible tsunami scenario for the region and determination of related earthquake parameters 3 high resolution tsunami simulation and computation of near shore and overland tsunami dynamics in the study area using tsunami simulation and visualization code namidance 4 determination of spatial distributions of tsunami characteristics maximum water elevations water velocities flow depths under the critical tsunami condition the results are based on the most recent descriptions of potential tsunami sources topographic and bathymetric databases and tsunami numerical models we present an innovative study concentrating on preparation of quantitative flow depths and inundation maps with a very high resolution bathymetry topographic dataset in the eastern mediterranean inundation maps will be used to analyze the effects of possible tsunamis the presented research is crucial to raising the awareness of government officials the public and other stake holders about the high probability of a tsunami event in turkey moreover the results of this study will help to plan for evacuation routes establish safe zones and assist in preparation for the tsunami creating public awareness and planning evacuation routes before the actual tsunami event happens

a time and magnitude predictable model for generation of shallow earthquakes in the aegean area repeat times of strong shallow mainshocks have been determined by the use of instrumental and historical data for 68 seismogenic sources in the aegean and surrounding area 34 n 43 n 18 e 30 e for 49 of these sources at least two interevent times three mainshocks are available for each source by using the repeat times for these 49 sources the following relation has been determined log t t 0 36m min 0 35m p a wheret t is the repeat time measured in years m p the surface wave magnitude of the preceding mainshock mmin the magnitude of the smallest earthquake considered and a parameter which varies from source to source a multilinear correlation coefficient equal to 0 89 was determined for this relation

modelling of tsunami generated by the giant late bronze age eruption of thera south aegean sea greece summary tsunami generated by the late bronze age lba eruption of thera were simulated using synthetic tide records produced for selected nearshore 20 m depths sites of northern crete the cyclades islands sw turkey and sicily inundation distances inland were also calculated along northern crete modelling was performed by incorporating fully non linear boussinesq wave theory with two tsunamigenic mechanisms the first involved the entry of pyroclastic flows into the sea assuming a thick 55 m 30 km3 flow entering the sea along the south coast of thera in three different directions all directed towards northern crete then a thin pyroclastic flow 1 m 1 2 km3 entering the sea along the north coast of thera directed towards the cyclades islands flows were modelled as a solid block that slowly decelerates along a horizontal surface the second mechanism assumed caldera collapse of 19 km3 and 34 km3 modelled as a dynamic landslide producing rapid vertical displacements calculated nearshore wave amplitudes varied from a few metres to 28 m along northern crete from pyroclastic flows and up to 19 m from caldera collapse 34 km3 volume inundation distances on crete were 250 450 m waves produced by pyroclastic flows were highly focused however as a function of sea entry direction smaller volume pyroclastic flows produced nearshore wave amplitudes up to 4 m in the cyclades islands north of thera wave amplitudes in the cyclades from smaller volume caldera collapse 19 km3 were up to 24 m whereas in sw turkey were as low as 2 1 and 0 8 m didim and fethye where lba tsunami deposits have been found wave amplitudes for the larger volume caldera collapse 34 km3 were generally 2 5 3 times larger than those generated by the smaller volume collapse 19 km3 these results provide estimates for understanding possible consequences of tsunami impact in lba coastal zones thus providing criteria at archaeological sites for detecting inundation damage as well as for contemporary hazard assessment they also provide additional criteria for deciphering homogenite layers in the abyssal stratigraphy of the ionian and eastern mediterranean seas

seismotectonics and seismic hazard modelling for southern bulgaria the seismotectonics of southern bulgaria and its surroundings have been reviewed and analysed and a catalogue has been compiled for the region we show that for southern bulgaria the seismicity characteristics focal mechanisms and stress inversions a confirm the hypothesis that the neotectonics of this region are similar to that of northern greece and the northern aegean sea with presently n s extension b indicate that the seismic energy release is mostly related to normal faulting with possibly some small strike slip component in the struma fault zone c result for this region in a frequency magnitude relation that suggest characteristic magnitudes around ms 7 0 and d indicate that seismic activity occurs in crustal fault zones rather than crisp fault planes a probabilistic seismic hazard analysis psha for southern bulgaria represents a typical case of seismic hazard for a tectonically complex region with large uncertainties in model parameters we show using a monte carlo approach that large uncertainties in seismic characteristics have relatively little effect on the psha output especially when compared with uncertainties associated with the attenuation function uncertainties in the seismotectonic model emerge strongest for the regions around pazardjik and jambol the western and eastern tails of the maritsa fault zone for six important economic centers in southern bulgaria we present the seismic hazard and their uncertainties with respect to attenuation and seismicity modelling our psha maps show for example regions with significant seismic hazard that exceed with 50 confidence a 1 annual probability of the peak ground acceleration exceeding 0 3 g future psha improvements for the region can be obtained by in order of decreasing significance a carefully mapped site responses or more accurate regional attenuation models b additional constraints on the seismic zones and c better constrained magnitude frequency distributions for example with independent regional strain rate information

regional focal mechanisms for earthquakes in the aegean area the distribution of the focal mechanisms of the shallow and intermediate depth h 40 km earthquakes of the aegean and the surrounding area is discussed the data consist of all events of the period 1963 1986 for the shallow and 1961 1985 for the intermediate depth earthquakes with m s 5 5 for this purpose all published fault plane solutions for each event have been collected reproduced carefully checked and if possible improved accordingly the distribution of the focal mechanisms of the earthquakes in the aegean declares the existence of thrust faulting following the coastline of southern yugoslavia albania and western greece extending up to the island of cephalonia this zone of compression is due to the collision between two continental lithospheres apulian eurasian the subduction of the african lithosphere under the aegean results in the occurrence of thrust faulting along the convex side of the hellenic arc these two zones of compression are connected via strike slip faulting observed at the area of cephalonia island the p axis along the convex side of the arc keeps approximately the same strike throughout the arc 210 nne ssw and plunges with a mean angle of 24 to southwest the broad mainland of greece as well as western turkey are dominated by normal faulting with the t axis striking almost ns with a trend of 174 for greece and 180 for western turkey the intermediate depth seismicity is distributed into two segments of the benioff zone in the shallower part of the benioff zone which is found directly beneath the inner slope of the sedimentary arc of the hellenic arc earthquakes with depths in the range 40 100 km are distributed the dip angle of the benioff zone in this area is found equal to 23 this part of the benioff zone is coupled with the seismic zone of shallow earthquakes along the arc and it is here that the greatest earthquakes have been observed m s 8 0 the deeper part inner of the benioff zone where the earthquakes with depths in the range 100 180 km are distributed dips with a mean angle of 38 below the volcanic arc of southern aegean

holocene palaeoenvironmental changes in agia paraskevi prehistoric settlement lamia central greece abstract holocene palaeoenvironmental changes in the area of the prehistoric settlement of megali vrysi close to the village of agia paraskevi in central greece 5 km east of lamia city were investigated the area is situated in the low flat alluvial plain on the outskirts of sperchios valley that is bordered nnw to ene by a rocky hilly ridge of the othrys mountain foothills 5 5 km away from the present coastline the megali vrysi site is considered to be an important mediterranean prehistoric commercial centre reconstruction of the palaeoenvironmental changes of the broader area adds new information concerning the general palaeogeographical setting of the settlement multidisciplinary research involved a detailed geomorphological survey combined with stratigraphical palaeontological and geophysical studies the penetrated strata differentiated into 4 units from top to bottom the first represents the archaeological strata the second consists of the freshwater marshy sediments while the third is the transition layer between the second and the deeper fourth group of marine lagoonal sediments the holocene stratigraphy data was combined with the 14 c ams dating results and showed a marine palaeoenvironment 5500 bc gradually having shifted to a coastal lagoonal one 3500 bc and finally changed to a freshwater marshy environment 2500 bc the comparison between ages and depths of the relative sea level points allowed the estimation of the sea level rise rate for the agia paraskevi area which is considerably lower than the one proposed for the aegean sea in the same time period this considerable offset is attributed to the intensive tectonic uplift of the study area due to the tectonic deformation of the sperchios valley and this is probably why the prehistoric coastal settlement remained on the surface and unaffected from the sea transgression for more than 7000 yrs during holocene

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

an alternative approach to probabilistic seismic hazard analysis in the aegean region using monte carlo simulation abstract the aegean is the most seismically active and tectonically complex region in europe damaging earthquakes have occurred here throughout recorded history often resulting in considerable loss of life the monte carlo method of probabilistic seismic hazard analysis psha is used to determine the level of ground motion likely to be exceeded in a given time period multiple random simulations of seismicity are generated to calculate directly the ground motion for a given site within the seismic hazard analysis we explore the impact of different seismic source models incorporating both uniform zones and distributed seismicity a new simplified seismic source model derived from seismotectonic interpretation is presented for the aegean region this is combined into the epistemic uncertainty analysis alongside existing source models for the region and models derived by a k means cluster analysis approach seismic source models derived using the k means approach offer a degree of objectivity and reproducibility into the otherwise subjective approach of delineating seismic sources using expert judgment similar review and analysis is undertaken for the selection of peak ground acceleration pga attenuation models incorporating into the epistemic analysis greek specific models european models and a next generation attenuation model hazard maps for pga on a rock site with a 10 probability of being exceeded in 50 years are produced and different source and attenuation models are compared these indicate that greek specific attenuation models with their smaller aleatory variability terms produce lower pga hazard whilst recent european models and next generation attenuation nga model produce similar results the monte carlo method is extended further to assimilate epistemic uncertainty into the hazard calculation thus integrating across several appropriate source and pga attenuation models site condition and fault type are also integrated into the hazard mapping calculations these hazard maps are in general agreement with previous maps for the aegean recognising the highest hazard in the ionian islands gulf of corinth and hellenic arc peak ground accelerations for some sites in these regions reach as high as 500 600 cm s 2 using european nga attenuation models and 400 500 cm s 2 using greek attenuation models

study of the crustal thickness and the subducting lithosphere in greece from gravity data the area of greece has experienced a complex tectonic history dominated by the subduction of the african plate beneath eurasia in this study the variations of the crustal thickness in the area of greece were obtained by means of the multiple source werner deconvolution mswd method applied to gravity data thicknesses of 40 49 km are estimated beneath the hellenides mountain belt to the west eastward thinning of the crust to thicknesses ranging from 25 km in the north to 30 km in the south is seen in the aegean region these results are in good agreement with recent seismological results demonstrating that the mswd method successfully treated the problem using the crustal model we derived we computed the gravity effect of the crust and extracted it from the bouguer anomaly we also extracted the gravity effect of the subducting lithosphere from the bouguer anomaly producing a residual map where most of the original gravity variation has been successfully removed the remaining anomalies appear related to near surface features and an area of low velocity mantle in the central aegean sea

the spatially extended 2006 april zakynthos ionian islands greece seismic sequence and evidence for stress transfer summary the seismic sequence at the southern part of zakynthos island ionian sea western greece during april and may of 2006 is investigated it consists of four moderate earthquakes 5 3 mw 5 7 that were followed by significant seismic activity source parameters of the significant events were determined using two different techniques teleseismic body wave modelling was employed for the major events of the sequence mw 5 6 although for the moderate ones the frequency wavenumber integration method was used the calculated fault plane solutions of the 2006 april seismic sequence revealed compressional regime in all cases more than 3500 microearthquakes were recorded and located using a local temporary network their spatial distribution indicated high concentration of seismic activity within an expanded area taking into account the magnitudes of the major events within this expanded area approximately 10 30 km 2 the focal depths varied between 10 and 25 km two main clusters were revealed the major events occurred in an area of low seismic activity that separates the two clusters seismic cross sections indicated a complex pattern of the hypocentre distribution with the activation of two nearly antithetical faults consistent with the determined focal mechanisms the northern cluster can be associated with a fault plane trending nnw sse and dipping towards sw although the southern cluster with a fault plane striking nw se and dipping towards ene finally coulomb stress analysis was performed to calculate the stress transfer and correlate it with the activated area positive lobes with stress more than 0 3 bars were obtained indicating that these values are large enough to increase the seismicity towards the observed nnw sse direction

search for a seasonal trend in earthquake occurrence in the hellenic arc abstract a search for a seasonal trend for earthquakes in the hellenic arc area was carried out considering main instrumental and shallow m 5 2 as well as intermediate depth m 6 0 events the seasonal trend was found to be statistically significant at the 95 level for m 6 0 intermediate depth events whereas no such trend was found for shallow events

late holocene sea level evolution of paros island cyclades greece abstract relative sea level rsl reconstructions are essential to answer a variety of scientific questions ranging from the investigation of crustal movements to the calibration of earth rheology models and ice sheet reconstructions it is generally assumed that most cycladic islands aegean sea greece are affected by a gradual subsidence attributed to the crustal thinning and to hydro isostatic processes that accompanied the post glacial rise in sea level in this paper we produce new rsl data from sedimentary records on paros island we compare and contrast these rsl data with published data from the nearby island of naxos our results are further compared with sea level predictions from two different gia models in an attempt to better quantify the tectonic regime of the wider study area our results suggest average tectonic subsidence rates close to 1 0 0 4 mm yr since 5500 cal bp these rates are not linear in time and have increased since 2500 cal bp

a palaeogeographic reconstruction of the seafront of the ancient city of delos in relation to upper holocene sea level changes in the central cyclades abstract palaeogeographical reconstruction of the seafront of the ancient city of delos is based on the recording and study of all available indicators of sea level change contemporary submerged beachrock formations and presently submerged areas of ancient human activity including ancient coastal constructions indicate the phases vertical direction extent and time frame of the changes the sea level along the coasts of delos has risen by a total of 2 15 m since the end of the hellenistic period this change occurred during two successive distinct phases of submersion initially by 1 35 m and then by another 0 80 m the sea s transgression into the ancient coastal zone by a width of at least 30 m radically altered parts of its geomorphology and resulted in the submersion of the ancient sea defences

seismic hazard in greece i magnitude recurrence two different methods are applied to the earthquake catalogue for greece makropoulos and burton 1981 mb catalogue to evaluate greek seismic hazard in terms of magnitude earthquake strain energy release and gumbel s third asymptotic distribution of extreme values it is found that there is a close relationship between results from the two methods in places where the cumulative strain energy release graphs include at least one well defined cycle of periodicity of strain release then the parameters of the third type asymptote are well defined with small uncertainties in almost all cases the magnitude distribution shows a remarkably good third type asymptotic behaviour the results are presented in the form of graphs and contour maps of annual and 80 year modes and magnitudes with 70 probability of not being exceeded in the next 50 and 100 years for six of the most heavily industrial and highly populated centres of greece magnitude hazard parameters are also derived and examined in more detail thereby illustrating the direct applicability of the methods in terms of zoning the close agreement between observed and predicted extreme magnitudes shows that the sample period considered 1900 1978 is long enough to obtain statistically stable estimates for athens the upper bound magnitude is found to be 6 7 0 3 within 100 km and 6 8 0 4 100 km from the two methods respectively whereas for corinth an earthquake of magnitude 6 5 has a mean return period of 43 years greece as a whole has an upper bound magnitude 8 7 0 6 and earthquakes of a size similar to the 1903 kithira event m 8 0 have a mean return period of about 200 years the significantly different maps contouring magnitudes of the annual and 80 year modes result from the fact that each place has its own distribution curvature for magnitude occurrence and thus they are not a linear extrapolation of each other however as longer return periods are considered these differences become small because the expected magnitudes approach the regional upper bound a feature common to all these maps is the existence of three well defined aseismic blocks 1 a the attikocycladic block 2 b the ptolemais basin and 3 c the block formed by the northeastern part of greece well defined areas of high seismic hazard which correlate with the most tectonically active areas are 1 a along the hellenic arc the greek albania border leukas cephalonia islands and the southeastern end of the arc 2 b the western end of the north anatolian fault and 3 c the chalkidiki peninsula and the northern sporadhes islands

a formulation for reliable estimation of active crustal deformation and its application to central greece summary a procedure for the analysis of data concerning seismic moment release and fault plane solutions for the estimation of active crustal deformation is proposed the formulation takes advantage of all the available historical and instrumental data for the calculation of the size of the deformation in a seismic zone and of all the reliable fault plane solutions which are available for a broader seismic belt for the determination of the shape of the deformation a detailed analysis of the errors involved in each parameter based on a monte carlo numerical method is suggested the proposed procedure is applied to a region of extensional tectonics in central greece the resulting seismic strain rates show that the dominant mode of deformation in the area is extension at a rate of the order of 6 mm yr and a mean azimuth of n25 w a vertical contraction rate of about 1 mm yr has also been calculated the results from geodetic measurements performed by billiris et al 1991 declare that the calculated seismic deformation represents about 60 per cent of the total strain of this area

the geometry of the wadati benioff zone and lithospheric kinematics in the hellenic arc abstract accurate locations of 961 shallow and intermediate depth earthquakes which occurred between 1956 and 1995 in the hellenic arc 34 39 n 19 28 e are used to define the plate boundaries in this area reliable fault plane solutions for 77 shallow and intermediate depth earthquakes are also used in order to define the interaction between the different plates in the arc an ocean continent type of interaction occurs on a curved surface which is defined by the shallow branch 20 100 km of the wadati benioff zone the intersection of this zone with the earth s surface is a curve which follows the convex outer side of the sedimentary arc western peloponnese west of cythera south coast of crete east coast of rhodes and dips at low angle 30 to the aegean sea coupling between the subducted oceanic crust and the overriding of the aegean lithospheric plate takes place on this surface the deep branch 100 180 km of the wadati benioff zone is dipping freely without coupling at a high angle 45 beneath the south aegean trough and the volcanic arc the high shallow seismicity h 20 km which is observed in the southwestern convex outer side of the arc ionian sea is attributed to the fast southwestward motion of the aegean plate location of strong deep earthquakes h 100 km in the fore arc area of the southwestern part of the hellenic arc west of cythera indicates that oceanic crust is destroyed in this part of the hellenic trench due to roll back of the descending lithospheric slab

time independent and time dependent seismic hazard in greece based on seismogenic sources abstract an improved procedure is followed to assess time independent andtime dependent hazard for 144 broad sites cities towns villages of greece in termsof expected macroseismic intensities at each one of these sites in this procedureseveral new results are taken into account source parameters based on new researchwork on seismicity and on other relative information new regionalization and im proved seismicity data parameters and anisotropic radiation at the seismic source anew relation for the attenuation of macroseismic intensities and the effect of localconditions site effects on the strong ground motion analytic relations and tables determined by this procedure permit the reliableassessment of time independent hazard in terms of macroseismic intensity in mmscale peak horizontal ground acceleration and velocity at each one of these 144sites and at any probability level time dependent hazard has been also assessed for these 144 broad sites in greece in terms of the probability for the occurrence of strong ground motion with macro seismic intensity i vii in mm scale at each one of these sites during the period1996 2010 comparison of the assessed time dependent hazard with observed ma croseismic intensities of the period 1950 1995 indicates that the time dependentmodel gives very reasonable results introduction

the 2003 lefkada earthquake field observations and preliminary microzonation map based on liquefaction potential index for the town of lefkada abstract a strong earthquake mw 6 2 occurred offshore the island of lefkada or lefkas on august 14 2003 the maximum intensity has been evaluated io viii ems at lefkada municipality while vi to vii intensities were evaluated at many other villages of the island the offshore nne ssw oriented strike slip right lateral fault was activated by the main shock this fault is the northern termination of the cephalonia transform fault the most characteristic macroseismic effects were extensive typical ground failures like rock falls soil liquefactions subsidence densification ground cracks and landslides these macroseismic effects are remarkably similar to those reported from some historical lefkada shocks e g 1704 1914 ms 6 3 and 1948 ms 6 5 sand boils and ground fissures with ejection of mud were observed at the seaside of the town of lefkada and in the villages of nydri and vassiliki in situ soil profiles are obtained based mainly on borings after the earthquake boreholes records with spt values standard penetration test are obtained and the simplified procedure originally developed by seed and idriss was employed to evaluate the liquefaction resistance of soils the results indicated that the silty sandy layer which lies beneath the artificial fill in the coastal zone in lefkada town had liquefied during the 14 august earthquake an attempt was also made to establish a preliminary microzonation map for lefkada town using the data from liquefaction potential index analyses our map was validated by the occurrence of liquefaction phenomena inside the town

hellenic unified seismological network an evaluation of its performance through snes method summary in this paper we analyse the location performance of the hellenic greek unified seismological network husn by seismic network evaluation through simulation method snes this method gives as a function of magnitude hypocentral depth and confidence level the spatial distribution of the number of active stations in the location procedure and their relative azimuthal gaps and confidence intervals in hypocentral parameters regarding both the geometry of the seismic network and the use of an inadequate velocity model greece is located on a tectonically active plate boundary at the convergence of the eurasian and african lithospheric plates and exhibits a high level of seismicity the husn monitors the seismicity in greek territory from 2007 at present it is composed by 88 seismic stations appropriately distribute in the area of greece the application of the snes method permitted us to evaluate the background noise levels recorded by the network stations and estimate an empirical law that links the variance of p and s traveltime residuals to hypocentral distance the statistical analysis of the p and s traveltime residuals allowed us to assess the appropriateness of the velocity model used by the husn in the location routine process we constructed snes maps for magnitudes of 2 2 5 and 3 fixing the hypocentral depth to 10 km and the confidence level to 95 per cent we also investigated by two different vertical sections the behaviour of the errors in hypocentral parameters estimates as function of depth finally we also evaluated fixing the hypocentral depth to 10 km and the confidence level to 95 per cent the magnitude of completeness through the application of the snes method we demonstrate that the husn provides the best monitoring coverage in western greece with errors that for 2 5 are less than 2 and 5 km for epicentre and hypocentral depth respectively at magnitude 2 5 this seismic network is capable of constraining earthquake hypocentres to depths of about 160 km and more and provides a threshold of completeness down to magnitude 2 for most of greek territory we delineate some seismogenic areas of southern greece that probably are not adequately covered by husn use of the snes technique could optimize upgrades of the network in these areas

the regional time and magnitude predictable model and its application to the alpine himalayan belt abstract the regional time and magnitude predictable model has been introduced and has been shown to be appropriate to describe the behaviour in the occurrence of mainshocks the model implies that the magnitude of the preceding mainshock in a seismogenic region that is the largest earthquake during a seismic excitation governs the time of occurrence and the magnitude of the expected mainshock in this region this model has been applied in 149 seismogenic regions of the alpine himalayan seismic belt the model probability for the occurrence of the next very strong main shock ms 6 5 during the decade 1993 2002 as well as the magnitude of this shock in each of these regions have been calculated furthermore two tests have been performed to check the validity of this model these tests have shown the reliability of the model and its superiority compared to the classical time independent model