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

seismicity and seismic hazard parameters evaluation in the island of crete and the surrounding area inferred from mixed data files abstract a study of the spatial distribution of seismicity and seismic hazard is undertaken for crete and the surrounding area cisa for the estimation of seismicity parameters cisa is divided in rectangular subregions by applying the centroid of strain energy technique we obtain seismicity parameter maps closely related to the tectonics of the area the b value from the magnitude frequency distribution is calculated by a maximum likelihood technique page 1968 bull seism soc am 58 1131 1168 as well as by gumbel s first asymptotic distribution of extreme values technique the b value shows consistent spatial variation along cisa for both techniques low b values are dominant in the western part of cisa while higher b values are present to the east side forming a pattern like a sleeping letter s this pattern may be attributed to the variation of the regional velocity of deformation finally we performed seismic hazard analysis for shallow and intermediate events from mixed historical and instrumental data files we estimated the regional maximum magnitude mmax as well as the other parameters like the activity rate of seismic events and the well known b parameter kijko and sellevoll 1989 bull seismol soc am 79 645 654

seismotectonics and the earthquake frequency magnitude distribution in the aegean area summary a study of aegean seismotectonics and the resulting frequency magnitude distribution on a broad scale is undertaken using the tectonic model of le pichon angelier this implies a tectonic moment release rate due to the spreading of the aegean of 17 8 times 1018 n m 1 yr 1 over the past 13 ma if stretching is due mainly to a series of normal faults dipping at about 45 in a seismogenic crust 10 20 km deep the moment magnitude relation from an instrumental magnitude catalogue is log m0 a bm with a 10 970 0 294 b 1 206 in si units this is established from 50 events of magnitude ms 5 3 whose scalar seismic moments m0 have been evaluated in a homogeneous manner for the region by spectral analysis of surface waves at 30 60 s period by contrast published body wave analyses from waveform modelling at 20 s period and moment tensor analyses seem to produce seismic moments which are lower by a factor of two or so on average this moment magnitude relation implies a seismogenic moment release rate due to stretching in the aegean of 14 times 1018 n m 1 yr 1 during the time period 1918 81 and 17 times 1018 n m 1 yr 1 for the period 1964 81 within a factor of two or so uncertainty this implies that the energy release in the brittle crust due to aegean spreading is substantially seismic within the stated accuracy and is also relatively stationary even when compared with the tectonic moment release rates a similar comparison using the same tectonic model shows that the subducting slab is sinking beneath the hellenic arc almost completely aseismically and that processes such as near vertical slab pull and confined thermal expansion could explain most of the observed seismic energy release by internal deformation of the slab the frequency magnitude statistics for the area of active extension has a characteristic earthquake of magnitude 7ms corresponding approximately to fault depths of 10 14 km for an aspect ratio of 2 and a strain drop of 10 4 this is close to the observed seismogenic depth 10 20 km for well determined earthquakes in the aegean area

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

the aegean region deep structures and seismological properties summary 3 d p wave velocity anomaly patterns the geometry of the hellenic wadatibenioff zone and of the seismically active fracture zones in the overlying continental wedge and the depth distribution of seismogenic properties seismic activity energy and b value for the aegean region are examined in this study the western and eastern parts of the area studied differ significantly in terms of the depth distribution of the considered seismological parameters and the velocity structures the results indicate different physical conditions in the western and eastern parts of the region in question data for the surface heat flow and the evolution of the volcanism in the aegean region since the early eocene are employed to interpret the results of the present study possible geodynamic processes at the plate boundaries between africa and eurasia are discussed

bayesian probabilities of earthquake occurrences in greece and surrounding areas the bayesian extreme value distribution of earthquake occurrences has been adopted to estimate the seismic hazard in some seismogenic zones in greece and surrounding regions seismic moment slip rate earthquake recurrence rate and magnitude were considered as basic parameters for computing the prior estimates of the seismicity these estimates are then updated in terms of bayes theorem and historical estimates of seismicity associated with each zone high probabilities for earthquakes withm 6 0 have been obtained for the northwestern part of greece as well as for the southwestern part of the hellenic arc

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

quantifying seismicity parameter uncertainties and their effects on probabilistic seismic hazard analysis a case study of iran probabilistic seismic hazard analysis psha can accommodate various sources of uncertainties and it provides a rational framework for the precise portrayal of the hazard of a given region often the information used in the psha is incomplete and uncertain therefore the question arises how the uncertainty of the input data affects the estimated hazard characteristics in this study sensitivity analysis sa was conducted to identify the most dominant inputs affecting the assessment of the key seismicity parameters sps including the mean seismic activity rate b value of gutenberg richter and the maximum possible earthquake magnitude m hbox max the study was applied in five areas of iran for which such analyses have not been conducted in previous studies subsequently monte carlo simulation was employed to determine the effects of the uncertain input parameters on psha relevant to spectral accelerations corresponding to 10 and 2 probability of exceedance at least once in 50 years for this purpose a unified and declustered earthquake catalogue was used for the five major seismotectonic provinces of iran alborz azarbayejan zagros central east iran koppeh dagh and makran the results showed that the last complete part of the catalogue has a significant effect on the estimated value of seismic activity and the b value in contrast its influence is insignificant on the area characteristic maximum possible earthquake magnitude for which the most influential inputs are the maximum observed earthquake and its uncertainty furthermore the uncertainties of the input sps affected the seismic hazard estimates substantially and led to significant variability in the estimated ground motion characteristics

an alternative method for a reliable estimation of seismicity with an application in greece and the surrounding area abstract an alternative method is proposed for the robust estimation of a and b values of the gutenberg richter relation the main hypothesis is that b values depend on material properties and the seismotectonic setting and therefore should vary relatively smoothly in space as far as the a values are concerned more sharp variations are allowed because these values determine the seismicity level once the b value is fixed the study area is organized into a grid and the a and b values are simultaneously determined for the whole grid by solving an appropriate linear system smooth b variations are imposed by introducing additional linear constraints similar to the occam9s inversion used in tomography studies the method is applied to greece and the surrounding area which is a high seismicity area the results are in very good agreement with previous studies and further enhance our knowledge for the study area moreover additional seismicity measures return periods probabilities etc are estimated robustly because they depend on the a and b values obtained for this area

u pb zircon geochronology of lower jurassic and paleozoic stikinian strata and tertiary intrusions northwestern british columbia new u pb zircon ages are reported from western stikinia devonian and pennsylvanian ages of volcanic rocks at oweegee dome confirm the presence of pre permian strata and with paleozoic and triassic detrital zircons from lower jurassic sandstone they help to demonstrate pre lower jurassic deformation and uplift the absence of pre paleozoic inherited zircon from all samples is consistent with nd sr isotopic data which suggest that stikinia consists mainly of juvenile crust u pb ages for posttectonic intrusions suggest that structures in skeena fold belt in the kinskuch area formed prior to eocene time five ages for felsic volcanic rocks from stratigraphically well constrained upper parts of the hazelton arc are approximately 196 199 ma and suggest near contemporaneity for cessation of volcanism in the areas studied the sinemurian or late sinemurian early pliensbachian ages are older than previously reported u pb and biostratigraphic ages for presumed correlative rocks to the west and westward migra

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

bayesian analysis of extreme earthquake occurrences part i probabilistic hazard model bayesian probability theory in conjunction with the model of extremes is used to develop a bayesian distribution of extreme earthquake occurrences by assuming that earthquakes represent a poisson process with exponential distribution of magnitudes the bayesian distribution represents the probability that m max the largest earthquake expected to occur within a period of t years will exceed some specified magnitude m and may be computed from the relationship p m max m t 1 t t t 1 f m n where n and t represent updated posterior bayesian estimates of the number of earthquakes and the time period of observation respectively and f m is the bayesian distribution of magnitudes each updated from prior estimates of seismicity using historical observations of earthquake occurrences through the application of bayesian probability theory the above distribution contains two features that make it more powerful and reliable than the conventional extreme value distribution first it incorporates statistical uncertainty in the estimation of seismicity in addition to the inherent uncertainty associated with the random nature of earthquake occurrences second it provides a rigorous means of combining prior information on seismicity such as geologica data with available historical observations of earthquake occurrences the last feature represents a major step toward the ability of earthquake engineers to systematically use information from geologists and seismologists regarding the seismic potential of faults and small regions in the probabilistic assessment of seismic hazards and provides a means of periodically updating estimates of earthquake occurrence probabilities as new seismicity data become available

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

earthquake hazard parameters in crete island and its surrounding area inferred from bayes statistics an integration of morphology of the seismically active structures and seismological data the study addresses the evaluation of earthquake hazard parameters such as maximum regional magnitude mmax and the slope of gutenberg richter law where b log e for the hellenic wadati benioff zone and the overriding lithospheric plate in the area of crete and its surroundings the seismicity of the area is divided in a cellular 1 0 1 0 manner allowing analysis of the localized earthquake hazard parameters and graphical representation of their spatial variation our approach incorporates the recently updated earthquake catalogue for greece and the adjacent areas the consideration of the morphology of the deep seismically active structures in the studied area and use of a probabilistic procedure for estimating the earthquake hazard parameters one of the main inconsistencies in the earthquake hazard assessment is the estimation of the maximum magnitude and the related uncertaint y the bayesian approach applied in the present is a straightforward technique for evaluating the earthquake hazard parameters and is based on the following assumptions poissonian character of seismic events flow a frequency magnitude law of gutenberg richter s type with cutoff maximal value for estimated parameter and a seismic catalogue having a rather sizeable number of events i e 50 events at least per cell for five cells in which the number of events is less than 50 an effort is made to produce synthetic data the re assessed parameters obtained from the synthetic data show no significant difference and the real data of the five cells are finally taken into account although the estimated uncertainty is high for four random cells we constructed hazard curves showing the probabilities that a certain magnitude m will be exceeded in one year and the return periods in years that are expected for a given magnitude these are particularly useful for the mapping of earthquake hazard in regions of either low or high seismic activity as is crete and the adjacent area the obtained results show that the w and e parts of both subducting and overriding plates differ in the spatial distribution of all the estimated earthquake hazard parameters the mmax distribution indicates strong coupling between the western portions of the interacting plates mmax 6 3 to the south of 36 n the smaller values of mmax mmax 1 0 are found to the south and east of crete for the wadati benioff zone and over the central part of the island and the area to the northeast of it cell 11 for the continental wedge which suggests nonuniform stress field and or heterogeneous material

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

seismic coupling and uncoupling at subduction zones seismic coupling has been used as a qualitative measure of the interaction between the two plates at subduction zones kanamori 1971 introduced seismic coupling after noting that the characteristic size of earthquakes varies systematically for the northern pacific subduction zones a quantitative global comparison of many subduction zones reveals a strong correlation of earthquake size with two other variables age of the subducting lithosphere and convergence rate the largest earthquakes occur in zones with young lithosphere and fast convergence rates while zones with old lithosphere and slow rates are relatively aseismic for large earthquakes results from a study of the rupture process of three great earthquakes indicate that maximum earthquake size is directly related to the asperity distribution on the fault plane asperities are strong regions that resist the motion between the two plates the zones with the largest earthquakes have very large asperities while the zones with smaller earthquakes have small scattered asperities this observation can be translated into a simple model of seismic coupling where the horizontal compressive stress between the two plates is proportional to the ratio of the summed asperity area to the total area of the contact surface while the variation in asperity size is used to establish a connection between earthquake size and tectonic stress it also implies that plate age and rate affect the asperity distribution plate age and rate can control asperity distribution directly by use of the horizontal compressive stress associated with the preferred trajectory i e the vertical and horizontal velocities of subducting slabs are determined by the plate age and convergence velocity indirect influences are many including oceanic plate topography and the amount of subducted sediments all subduction zones are apparently uncoupled below a depth of about 40 km and we propose that the basalt to eclogite phase change in the down going oceanic crust may be largely responsible this phase change should start at a depth of 30 35 km and could at least partially uncouple the plates by superplastic deformation throughout the oceanic crust during the phase change

transvaporite model of ore genesis and an exploration strategy for new giant ore deposits abstract in the current work we stand for the revival of the transvaporite ore genesis model which was introduced by hungarian academician e szadeczky kardoss more than half a century ago but has now fallen out of favor and superseded by the orthomagmatic model our arguments in support of the transvaporite model are based on the contemporary overpressure theory developed for mesozoic cenozoic petroleum basins we propose a new variant of the transvaporization model whereby the formation of giant ore deposits occurs in the areas where former petroleum rich basins are intersected by large igneous provinces lips at such sites structural magmatic activity leads to hydrocarbon deposits being destroyed and many new ore deposits being created beneath a new regional volcanic fluid seal built by rapidly accumulating up to 3 4 km in 1 ma lava flows in such conditions a zone of significant overpressure that is 1 4 1 8 times higher than hydrostatic pressure develops subsequently under the influence of compressive mechanism of mass transfer gas saturated brines of sedimentary rocks migrate toward intruding melts and then mix with them as a result unusual rocks transvaporites are formed and giant ore deposits created here we review six supergiant ore deposits of various types and ages with different associations of metals and host rocks including the norilsk district in russia cu ni co pt pd el teniente los bronces district in chile cu mo almaden deposit in spain hg ermakovskoe deposit in russia be pebble copper deposit in southern alaska cu mo au and olympic dam deposit in southern australia u cu au ree noting that all listed metals in each and every deposit do reach giant reserves in all these deposits transvaporization appears to play the key role in ore genesis given the 1 short duration of the main ore genesis stage a significant practical implication of the transvaporite model is that it should modify future strategies for ore deposits exploration instead of pursuing just any deposit exploration efforts should focus specifically on giant ore deposits concentrating search efforts at the sites where former petroleum basins have been intersected by lips basin analysis of enriched oil and gas provinces is already being conducted in detail by seismic transects involving two dimensional cross sections and areal surveys followed by three dimensional mapping of productive reservoirs the same strategy should be applied to ore bearing regions but at better precision and accuracy given the smaller velocity contrast in seismic wave propagation in ore rocks compared with oil and gas bearing sedimentary rocks important advances in the ore geology of lips such as geological mapping and gravity and magnetic surveys have already produced significant new data these studies can be divided into two types which first involve a general description of the lip and are then followed by an investigation of major intrusions likely to be directly linked to ore genesis a combination of these investigations into hydrocarbon basins and lips will lay the foundation for transvaporite exploration which will be the key criterion for the successful search for new giant ore deposits

seismicity depth pattern seismic energy and b value depth variation in the hellenic wadati benioff zone abstract the statistics of the vertical distribution of the foci of earthquakes which occurred in the hellenic wadati benioff zone during the period 1964 1982 show that the seismicity pattern energy and b value of the frequency magnitude relation vary with depth in a specific manner the seismicity patterns of the western and the eastern flanks of the hellenic subduction zone vary with depth in a similar manner whereas the seismic energies and b value depth variations for these two flanks of the subduction zone do not show such a similarity

application of a bayesian approach for estimation of seismic hazard parameters in some regions of the circum pacific belt the maximum possible regional magnitude mmax and other seismic hazard parameters like which is the slope of gutenberg richter law and which is the intensity rate of seismic activity are estimated in eight seismic regions of the west side of the circum pacific belt the bayesian approach as described by pisarenko et al 1996 pisarenko and lyubushin 1997 1999 is a straightforward technique of estimating the seismic hazard the main assumptions for the method applied are a poissonian character of seismic events flow a frequency magnitude law of gutenberg richter s type with cutoff maximum value for the estimated parameter and a seismic catalog which have a rather sizeable number of events we also estimated the quantiles of the probabilistic distribution of the apparent mmax for future given time length intervals

bayesian analysis of extreme earthquake occurrences part ii application to the san jacinto fault zone of southern california abstract the bayesian extreme value distribution of earthquake occurrences developed in the first part of this study is tested and applied to the estimation of seismic hazards for the san jacinto fault zone of southern california prior estimates of seismicity are developed from seismotectonic data based on standard seismological relationships among seismic moment slip rate earthquake recurrence rate and magnitude these estimates are then updated using bayes9 theorem and historical estimates of seismicity associated with the san jacinto fault zone bayesian extreme value distributions available from the literature are found either to overestimate exceedance probabilities of earthquake occurrences or require more complex computations as compared to the distribution proposed in this study on the other hand the conventional extremevalue distribution of earthquake occurrences first proposed by epstein and lomnitz 1966 was found to give results consistent with the bayesian distribution of this study if updated estimates of the seismicity parameters are used and the standard deviations of these parameters are restricted to be less than about 25 per cent of their mean values the bayesian analysis of extreme earthquake occurrences for the 300 km long san jacinto fault zone indicated a rather large sensitivity to the uncertainty associated with the prior seismotectonic estimate of seismicity using moderate estimates of this uncertainty magnitudes of 6 2 6 9 7 1 7 4 and 7 5 are found to be associated with return periods at 10 50 100 500 and 1000 yr for an upper bound magnitude of 7 5 m s on the fault zone these estimates lie approximately midway between those based on historical and seismotectonic estimates of seismicity estimated magnitudes are reduced significantly for return periods of 50 to 1000 yr if upper bound magnitude is restricted to a value of 7 0 m s closer to the largest historical earthquake observed on the zone in this case for example the 100 and 1000 yr earthquakes have magnitudes of 6 8 and 7 0 respectively

greek tectonics and seismicity abstract the validity of existing tectonic models for the area of greece is examined in the light of the new recalculated parameters for earthquakes of the region makropoulos and burton 1981 relocated hypocentral positions are extracted from the catalogue to form radial and vertical distance depth cross sections centred on a reference point near the mid point of the aegean volcanic arc and these are used to form a three dimensional topography of the base of earthquake occurrence below 60 km isodepth maps are extracted from this topography as both three and two dimensional map presentations these maps reveal several significant features of deep seated tectonic processes in the region isodepths exceeding 150 km are seen in the northwest aegean and these are more closely linked to the sporadhes and gulf of thermaicos rather than the north aegean trough the 150 km isodepths are also seen in the northeast aegean straddling the dardanelles in the northeastern part of the peloponnesus gulf of saronikos and eastern gulf of corinth in the southern peloponnesus towards crete and extending from north of kos to south of rodos the largest extent of deepest activity is seen south of rodos and this continues towards southwest of turkey the subduction zone of the hellenic arc is clear but smooth benioff zones are not the norm and these data show that structural complexity is more readily observed it is concluded that none of the proposed tectonic models completely explain the observed activity over the whole area and rather than propose yet another model places where further work is still particularly necessary are identified

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

maximum likelihood estimation of earthquake hazard parameters in the aegean area from mixed data the maximum likelihood estimation of earthquake hazard parameters has been made in the aegean and adjacent regions on the basis of a procedure which utilizes mixed data containing incomplete files of large historical events and complete files of most recent earthquakes the entire earthquake catalog used covers the period from 479 b c to 1985 a d the maximum regional magnitude mmax the activity rate of the seismic events the mean return period r of earthquakes with a certain lower magnitude m m as well as the parameter b of the magnitude frequency relationship have been determined for eighteen different seismotectonic segments the fore arc and back arc regions and the area examined as an entity the determination has also been carried out for sub crustal shocks in the south aegean assuming that the earthquake hazard is an increasing function of mmax and a decreasing function of r we suggested a relative hazard scale to classify segments by hazard level based on their mmax and r it is shown that in general the hazard is higher in the back arc segments than in the fore arc ones high differences of the b parameter and the hazard level from segment to segment reflect the high seismotectonic complexity and crustal heterogeneity