a new method to estimate the overtopping and overflow discharge at over washed and breached dikes abstract most of the experience collected on wave overtopping is concentrated on emerged or zero freeboard structures and only few experiments are available on over washed dikes the experience on submerged crest conditions is principally related to rubble mound structures and limited to the wave reflection and transmission processes the existing tools for the prediction of the average wave overtopping discharge q at dikes are therefore targeted to represent overtopped structures leading to cautious estimates at over washed dikes and unrealistic overestimations in case of catastrophic scenarios such as breached dikes this paper proposes a new conceptual and practical method for the prediction of q that is valid for both over washed and fully breached dikes it consists of three physically based formulae whose coefficients are fitted on a new numerical database of smooth structures under variable wave attack the predictions are compared with the new numerical results and the data and the tools available from the literature i e experimental data formulae and neural network the new method gives a more realistic representation of the overtopping and overflow processes reducing significantly the overestimation in case of breaching and being at least as accurate as the existing tools in case of over washing

moment magnitude relations based on strong motion records in greece in this work the variation of the local magnitude mlsm derived from strong motion records at short distances is examined in terms of moment magnitude m w strong motion data from greek earthquakes are used to determine the strong motion local magnitude mlsm by performing an integration of the equation of mo tion of the wood anderson wa seismograph subjected to an input acceleration the most reliable strong motion data are utilized for earthquakes with seismic mo ments log m 0 22 0 dynecm and calculated local magnitudes mls m 3 7 the correlation between the seismic moments log m0 and the calculated local magni tudes mlsm using strong motion records is given by log m 0 1 5 mcsu 16 07 which is very similar to that proposed by hanks and kanamori 1979 moreover it is shown that mls m is equal to moment magnitude mw for a large mls m range 3 9 to 6 6 comparison of the strong motion local magnitude and the me magnitude estimated in greece ml n and surrounding area shows a systematic bias of 0 4 to 0 5 similar to the difference that has been found between m w and mlgr for the same area the contribution of the local site effects in the calculation of the local magni tude mlsm is also considered by taking into account two indices of soil classification namely rock and alluvium or the shear wave velocity vs30 of the first 30 m based on nehrp 1994 and ubc 1997 an increase of mls m by 0 16 is observed for alluvium sites alternative relations showing the mls m variation with v 3 are also presented finally examination of the wa amplitude attenuation log a0 with distance shows that the jennings and kanamori 1983 relation for a 100 km is appropriate for greece the same results confirm earlier suggestions that the 0 4 to 0 5 bias between mlgr and mw also mlsa4 should be attributed to a low static magnification 800 of the athens wa instrument on which all other m l relations in greece have been calibrated

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

source parameters of some large earthquakes in the eastern mediterranean region based on an itertive maximum entropy technique teleseismicp waves of some large earthquakes that occurred in the eastern mediterranean region have been analysed by using an iterative maximum entropy technique in order to obtain the independent spectral parameters the long period spectral level 0 and the corner frequencyf0 of the far field displacement spectra

extreme coastal responses using focused wave groups overtopping and horizontal forces exerted on an inclined seawall abstract total wave group overtopping and maximum horizontal force responses are investigated for an idealised seawall dike on a plane beach subject to compact focused wave attack using both laboratory and numerical wave flumes the wave group interactions have very short durations such that extraneous reflections from the wavemaker arrive long after the main interaction these short test durations facilitate the use of large ensembles of tests to explore the sensitivity of overtopping and force responses to variations in focus location phase angle at focus and linear focus wave amplitude the scope of the laboratory wave flume tests is broadened by accurate numerical simulation based on a 1dh hybrid boussinesq nlsw model for a given focus location and linear focused wave amplitude variations in phase lead to an order of magnitude change in the group overtopping volume substantial increases in overtopping volume owing to the use of linear wavemaker theory compared to second order theory are also observed these observations have implications for phase independent empirical relationships derived using linear paddle signals in physical experiments examination of the incidence of wave groups parametrically optimised for maximum and minimum overtopping volumes indicates that the overtopping volume may be optimised by minimising reflections of pre overtopping waves within the group while maximising the amplitude of the first overtopping bore numerical predictions of horizontal seawall forces are obtained using fluid impulse derivatives and hydrostatic pressures obtained from the shallow water model within the shallow water model framework hydrodynamic force contributions included in the fluid impulse method are observed to be small relative to the hydrostatic pressure force the parametric dependence of the horizontal non impulsive forces on the seawall is very similar to that of the overtopping volumes with clear bands of large values observed as a function of phase and focus location for a given amplitude this suggests that the parametric optimisation of focused wave groups is a robust method for the investigation of multiple coastal responses such as overtopping forces and runup

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

spectral characteristics of the 1986 september 13 kalamata southern greece earthquake summary the seismic source parameters seismic moment m source dimension r fault length 1 average displacement u shear stress drop aa radiated energy es and apparent stress n a are calculated for the kalamata southern greece earthquake of 1986 september 13 these source parameters are obtained by using teleseismic p and sh wave spectra and making use of three independent spectral parameters the long period spectral level a the corner frequency f and the parameter e which controls the high frequency decay of the displacement spectrum the calculated far field spectra are based on the direct phases of pand s waves and they have been corrected for the instrumental response and for an average radiation pattern assuming normal faulting mechanism the striking feature of the obtained results is the low stress drop value of about 6 7 bar which is in deviation from the average value 30 bar for interplate earthquakes a seismic moment of 1 9 x and 2 2 x loz4 dyne cm a fault length of about 22 and 11 km and an average displacement of 15 and 9 cm are obtained on the basis of p and s waves respectively

relationship between the 13 may 1995 kozani grevena nw greece earthquake and the polyphyto artificial lake abstract on 13 may 1995 a strong earthquake of m s 6 6 struck the cities of kozani and grevena in northwestern greece this region is characterized by low seismicity in the same area three hydroelectric dams have been operating for the last 30 years one of them the polyphyto dam is located only 40 km from the epicenter of the 13 may earthquake in the present work all available seismological aspects of the main event such as focal properties and source parameters together with foreshock and aftershock characteristics of the earthquake sequence are considered in order to examine whether the water level changes behind the polyphyto dam induced the unusual seismic activity in this area thus a detailed examination of the seismic activity is made and this is compared to the seismotectonic regime of the region and the reservoir loading from 1976 to 1995 the results show that there is no obvious correlation between seasonal or sharp fluctuations in the water level and the seismicity of the region except once during 1989 moreover comparison with other previous cases of induced seismicity in greece and in other countries shows no similarities to the kozani grevena earthquake sequence it is concluded that the kozani grevena earthquake is therefore an event in the framework of the regional seismicity rather than an event triggered by the impounding of the polyphyto artificial lake

seismic moments of earthquakes at the western hellenic arc and their application to the seismic hazard of the area tselentis g a stavrakakis g m o ulos k latousakis j and drakopoulos j 1988 seismic moments of earthquakes at the western hellenic arc and their application to the seismic hazard of the area tectonophysics 148 73 82 seismic moments of 45 large earthquakes m 2 5 2 which occurred in the southwestern part of the hellenic arc trench system between 1950 and 1981 were used to express the frequency of occurrence of earthquakes in terms of the subduction rate and the largest seismic moment likely to occur in the region for this purpose a moment versus magnitude relationship for earthquakes characteristic of the region was derived and the subduction rate was estimated from seismic moment rates the hellenic arc trench system is a subduction zone of about 1000 km where the african lithosphere is subducting under the aegean lithospheric plate in a roughly sw ne direction this motion of the hellenic consuming boundary with respect to africa results from three different processes the northward motion of the african plate the aegean extensional spreading and the westward motion of turkey mckenzie 1970 1978

andean foothills structures in northern magallanes basin argentina the foothills of the northern segment of the magallanes basin between 47 and 49 s latitudes record the development of a complex fold and thrust belt in the patagonian cordillera during the late miocene upper paleozoic sedimentary and metasedimentary rocks and thick sequences of lower cretaceous deposits with well defined source and reservoir rocks are deformed by the andean events the structure is characterized by a triangle zone and a series of related underthrusts which define a nonemergent backthrust system at the mountain front differences in the degree of deformation from south to north reveal the evolution of the triangle zone the stratigraphy of the molasse deposits constrains the beginning of the deformation at least to the early tertiary although the final structure was developed during the late miocene these deformed deposits are covered by extensive late miocene horizontal retro arc basalts analysis of the evolving subduction zone located west of and beneath the study area shows that the formation of a subsequent volcanic gap in the magmatic arc and the development of extensive retro arc basalts are related to the collision of a segment of the chile ridge during the late miocene the final deformation and uplift of the patagonian cordillera fold and thrust belt at these latitudes are closely linked to this collision

source parameters of the 1980 mammoth lakes california earthquake sequence from the more than 1500 mammoth lakes earthquakes recorded on three component digital seismographs spudich et al 1981 150 were used in an analysis of the locations mechanism and source parameters a composite fault plane solution of nine earthquakes 3 9 m 5 1 defines a right lateral strike slip mechanism on a steeply dipping nearly east west plane striking s75 e or left lateral strike slip on a nearly north south plane striking n10 e vertical cross sections of well located aftershocks indicate possibly three east west planes that coincide with the locations of the four largest earthquakes with ml 6 0 using the spectral analysis of s waves brune 1970 source parameters for 67 earthquakes were determined forty eight had magnitudes greater than or equal to 3 0 seismic moments ranged from 9 20 1018 dyn cm to 2 33 1024 dyn cm earthquakes with seismic moment greater than about 1 0 1021 dyn cm had nearly constant stress drops 50 bars earthquakes with seismic moment less than about 1 0 1021 dyn cm had stress drops that apparently decrease as seismic moment decreases

moment magnitude scaling in the aegean area abstract sixteen new determinations of scalar seismic moment from spectral modelling of rayleigh waves at 30 60 s period in the aegean area are presented when combined with earlier results obtained by a similar method the moment magnitude relationship from 50 events in the magnitude range 5 3 m s log m o 1 5 m s 9 198 0 317 for a constant stress drop dislocation model and m o in n m in contrast 15 published moments from body wave modelling at 20 s period and moment tensor inversion at periods greater than 45 s give log m o 1 5 m s 8 823 0 248 the surface wave results imply stress drops of 25 12 25 bar for the dislocation model and the body wave results imply systematically higher stress drops of 55 27 55 bar compared to 24 bar from field observation of the gulf of corinth sequence and 7 12 bar from inversion of body wave spectra and aftershock studies the latter are likely to be underestimates however the factor two scatter in the stress drops determined from the moment magnitude relation is much less than the factor four error in the estimated stress drop which might be introduced by model dependent systematics effects and these discrepancies may not be significant if the stress drop is free to vary then log m o 1 206 0 105 m s 10 970 0 632 surface waves log m o 1 160 0 181 m s 11 027 0 338 body waves this shows that the discrepancy between the two sets of results in negligible at m o 5 5 and thereafter increases slightly with earthquake size indicating that the underlying cause of the systematic difference in seismic moment for a given magnitude may be related to source size

a numerical model of wave overtopping on seadikes this paper describes the development of a numerical model for wave overtopping on seadikes the model is based on the flux conservative form of the nonlinear shallow water equations nlsw solved with a high order total variation diminishing tvd roe type scheme the goal is to reliably predict the hydrodynamics of wave overtopping on the dike crest and along the inner slope necessary for the breach modelling of seadikes besides the mean overtopping rate the capability of simulating individual overtopping events is also required it is shown theoretically that the effect of wave breaking through the drastic motion of surface rollers in the surfzone is not sufficiently described by the conventional nonlinear shallow water equations neglecting wave setup from the mean water level and thus markedly reducing the model predictive capacity for wave overtopping this is significantly improved by including an additional source term associated with the roller energy dissipation in the depth averaged momentum equation the developed model has been validated against four existing laboratory datasets of wave overtopping on dikes the first two sets are to validate the roller term performance in improving the model prediction of wave overtopping of breaking waves the last two sets are to test the model performance under more complex but realistic hydraulic and slope geometric conditions the results confirm the merit of the supplemented roller term and also demonstrate that the model is robust and reliable for the prediction of wave overtopping on seadikes

numerical study of combined overflow and wave overtopping over a smooth impermeable seawall abstract a numerical wave flume is used to investigate the discharge characteristics of combined overflow and wave overtopping of impermeable seawalls the numerical procedure computes solutions to the reynolds averaged navier stokes equations and includes the generation of an irregular train of waves the simulation of wave breaking and interaction with a sloping impermeable wall the numerical model is first tested against published experimental observations approximate analytical solutions and empirical design formulae for the cases of pure overflow and pure overtopping a sequence of numerical experiments simulating combined overflow and overtopping are described the results are used to determine empirical discharge formulae of the form used in current practice

validated coastal flood modeling at imperial beach california comparing total water level empirical and numerical overtopping methodologies abstract flood extent field observations collected during a winter storm h s 1 8 m t p 14 s coinciding with a spring high tide are used to evaluate the accuracy of static bathtub and hydrodynamic coastal flood modeling methodologies static models rely on empirically calculated wave setup or runup and simply compare total water level twl to land elevation the dynamic model resolves temporally variable overtopping rates overland flow urban features and storm system drainage swan a numerical wave model transformed deep water buoy spectra to the nearshore static twls were calculated using swan output and an empirical runup model numerical xbeach and empirical eurotop overtopping models parameterized with survey data and swan bulk wave statistics estimated temporally variable overflow rates along representative transects for overland flow model input xbeach model mode hydrostatic nonhydrostatic boundary depth and random realizations significantly affected overtopping rates nonhydrostatic mode estimated order of magnitude larger overflow volumes suggesting the importance of incident waves particularly in near threshold conditions boundary depth and random realizations varied overflow rates approximately fourfold field observations showed static twl models performed poorly maximum runup substantially overestimated flood extent and setup predicted no flooding all dynamic models reasonably predicted flood extent despite significant overflow volume differences backshore topography and flow dynamics are important flood extent controls accurate near threshold coastal flood predictions require dynamic overland flow modeling parameterized with temporally variable overtopping estimates and site specific beach and backshore topography

the seismology of greece abstract a review and a bibliography are given of the seismological literature for the area of greece in the period from 1950 up to the present time the aim is to incorporate all aspects of seismology starting with instrumental installations passing on to earthquake catalogues statistics and effects and ending up with structural properties and seismotectonics the purpose is to provide a service to every geophysicist who has an interest in this tectonically complex area and particularly to the numerous researchers engaged in geophysical expeditions to greece

seismic source parameters from a new dial up seismological network in greece a regional dial up pt telemetric network of eight digital short period seismic stations has been in full operation since the beginning of 1995 in greece during the first year of full operation three destructive earthquake sequences struck different regions of central and northern greece the dial up network managed to successfully record more than 85 of these seismic events including foreshocks main shocks and aftershocks and 45 of these events were selected in order to determine their seismic source parameters by spectral analysis the results show that seismic moment correlates very well with earthquake magnitude fault radius and fault displacement the determined scaling relations are in general agreement with those obtained by other studies for greek earthquakes that used different methodologies since digital seismic instrumentation is now expanding in greece these first results from spectral analysis of digital short period data can be considered useful for future seismic hazard studies

source processes of the 1981 gulf of corinth earthquake sequence from body wave analysis abstract teleseismic long period body waves from the 24 february 1981 gulf of corinth earthquake and its two principal aftershocks of 25 february 02h35m and 4 march 21h58m 1981 are studied to determine source characteristics focal mechanisms along with observed surface fault breaks suggest that the corinth earthquake sequence represents normal faulting due to the n s trending extension depths of the three shocks estimated by matching synthetic seismograms to observations are found to lie between 4 and 12 km the azimuthal variation of observed body wave duration indicates that the main shock is a multiple event and that the main rupture occurred about 3 to 4 sec after a relatively small foreshock and propagated toward the w nw seismic moments deduced from the body wave synthetics are 8 1 10 25 2 7 10 25 and 2 2 10 25 dyne cm for the main 25 february and 4 march shocks respectively average final displacements and stress drops are estimated to be 37 cm and 10 bars for the main shock for a circular fault of radius 15 km 22 cm and 8 bars for the 25 february shock and 18 cm and 7 bars for the 4 march shock for circular faults of radius 11 km the striking features of the earthquake sequence are the low stress drops of the main shock and its two principal aftershocks and the clear eastward migration of aftershock activities the unusually long source time function rise times 4 sec for the main shock 2 5 sec for both aftershocks and low stress drops suggest an overall slow energy release during the earthquake sequence

simulation of wave overtopping by an incompressible sph model the paper presents an incompressible smoothed particle hydrodynamics sph model to investigate the wave overtopping of coastal structures the sph method is a grid less lagrangian approach which is capable of tracking the large deformations of the free surface with good accuracy the incompressible algorithm of the model is implemented by enforcing the constant particle density in the pressure projection the sph model is employed to reproduce a transient wave overtopping over a fixed horizontal deck and the regular irregular waves overtopping of a sloping seawall the computations are validated against the experimental and numerical data and a good agreement is observed the sph modelling is shown to provide a promising tool to predict the overtopping characteristics of different waves the present model is expected to be of practical purpose if further improvement in the spatial resolution and cpu time can be adequately made

a 2d numerical model of wave run up and overtopping a two dimensional 2d numerical model of wave run up and overtopping is presented the model called ott 2d is based on the 2d nonlinear shallow water nlsw equations on a sloping bed including bed shear stress these equations are solved using an upwind finite volume technique and a hierarchical cartesian adaptive mesh refinement amr algorithm the 2d nature of the model means that it can be used to simulate wave transformation run up overtopping and regeneration by obliquely incident and multi directional waves over alongshore inhomogeneous sea walls and complex submerged or surface piercing features the numerical technique used includes accurate shock modeling and uses no special shoreline tracking algorithm or shoreline coordinate transformation which means that noncontiguous flows and multiple shorelines can easily be simulated the adaptivity of the model ensures that only those parts of the flow that require higher resolution such as the region of the moving shoreline receive it resulting in a model with a high level of efficiency the model is shown to accurately reproduce analytical and benchmark numerical solutions existing wave flume and wave basin datasets are used to test the ability of the model to approximate 1d and 2d wave transformation run up and overtopping finally we study a 2d dataset of overtopping of random waves at off normal incidence to investigate overtopping of a sea wall by long crested waves the data set is interesting as it has not been studied in detail before and suggests that in some instances overtopping at an angle can lead to more flooding than at normal incidence

efficient and robust wave overtopping estimation for impermeable coastal structures in shallow foreshores using swash abstract estimation of wave overtopping over the crest of coastal structures is crucial to design effective and cost efficient countermeasures against storms semi empirical formulas are often used for wave overtopping assessment but they are not always applicable for complex structures which exist in reality e g a storm wall on a dike in a shallow or very shallow foreshore detailed numerical models such as eulerian and lagrangian rans models have potential to simulate overtopping of complex coastal structures with good accuracy however such models require significant computational resources the use of such models is often not feasible for the design of coastal structures which often requires multiple iterations and model runs over a reasonably long period of time e g wave trains with 1000 individual waves in this paper we investigated the applicability of the simplified depth integrated wave transformation model swash for wave overtopping estimation of impermeable coastal structures in shallow foreshores the validation results demonstrate the capability of swash to predict mean wave overtopping discharge with good accuracy compared to results from four different overtopping experimental campaigns comprising 124 individual cases the overall performance of swash to estimate mean wave overtopping discharge is as accurate as those obtained by semi empirical equations in literature however in order to obtain accurate mean wave overtopping discharge with the swash model the incident wave properties at the toe of the dike need to be accurately reproduced for cases where this is not possible a correction method is proposed in this paper detailed validation of the instantaneous wave overtopping also shows a good agreement with physical model data in one example a single intensive overtopping event was not well resolved by the swash model and the instantaneous wave overtopping was under predicted however this did not contribute significantly to the mean wave overtopping discharge an additional advantage of the swash model is that specific coastal structure geometries can be modelled in swash if they are not covered by semi empirical equations even in a case with rapidly varied flow e g vertical wall on a dike the model shows sufficient robustness in this paper the details on the swash model configuration and post processing methods are outlined to enable the reader to reproduce reliable wave overtopping estimation over impermeable coastal structures in shallow foreshores

a source study of the thessaloniki northern greece 1978 earthquake sequence summary the thessaloniki northern greece earthquake sequence appears to have occurred along faults forming a graben structure this graben situated in the border region between the serbomacedonian massif and the vardar zone is bounded to the south west by clearly exposed north west striking north east dipping normal faults relative hypocentre determinations fault plane solutions surface faulting and the aftershock distribution suggest that some of these faults have been reactivated during the 1978 earthquakes the source parameters of the mainshock mb 6 1 ms 6 4 were determined by computing body wave synthetic seismograms in the time domain and comparing them with the observed this modelling constrained the orientation of faulting determined by the p wave fault plane solution it also constrained the source depth to 6 mp 2 km similar depths were calculated by a relative relocation method for the other three large events of the sequence the dislocation time function required for the far field had a total duration of 9 mp 1 5 s the body wave moment was 5 2 mp 1 8 times 1025 dyne cm for a fault length of 35 km and a fault width of 17 km both estimated from the aftershock distribution the static stress drop was found to be 4 bar an accelerograph record of the mainshock shows two distinct events 3 4 s apart these two events were unresolved by the long period data in the far field but the unusually long duration of the mainshock time function suggests an overall slow energy release which probably occurred as a sequence of events close in space and time seismic energy released in this fashion can account for waveform complexities observed at some stations

numerical simulation of wave overtopping of coastal structures using the non linear shallow water equations a one dimensional high resolution finite volume model capable of simulating storm waves propagating in the coastal surf zone and overtopping a sea wall is presented the model amazon is based on solving the non linear shallow water nlsw equations a modern upwind scheme of the godunov type using an hll approximate riemann solver is described which captures bore waves in both transcritical and supercritical flows by employing a finite volume formulation the method can be implemented on an irregular structured boundary fitted computational mesh the use of the nlsw equations to model wave overtopping is computationally efficient and practically flexible though the detailed structure of wave breaking is of course ignored it is shown that wave overtopping at a vertical wall may also be approximately modelled by representing the wall as a steep bed slope the amazon model solutions have been compared with analytical solutions and laboratory data for wave overtopping at sloping and vertical seawalls and good agreement has been found the model requires more verification tests for irregular waves before its application as a generic design tool

coseismic crustal deformation on a fault zone defined by microseismicity in the pavliani area central greece summary pavliani is an area of high microseismicity in northern central greece there is no evidence in the historical record of large damaging earthquakes in this area since at least 600 bc we examine contemporary crustal deformation in this area using microearthquake data recorded during 1983 84 by the volos seismic network principally and to a lesser extent by the patras seismic network the microseismicity 1 4 6 ml defines an approximately vertical fault zone trending wsw ene of 55 km length and 25 km depth the fault plane solution for the 4 6 m earthquake shows a strike consistent with the trend of the microseismicity zone and an extension direction consistent with many large earthquakes in central greece associated with the extensional greater aegean spectra of the microearthquakes are estimated using p waves obtained by selective windowing designed to exclude other p phases from the coda seismic moments in the range 1 95 x 10 n m are obtained accompanied by estimates of seismotectonic source parameters including source radii average stress drop and average coseismic slip of prime utility is an excellent correlation found between seismic moment and magnitude and with coseismic slip this allows heterogeneity in the distribution of individual microearthquake source parameters to be mapped onto the vertical fault zone plane and the history of coseismic deformation for the whole seismicity observed during 1983 84 to be examined using cumulative slip and moment release rate peaks of high moment release rate occur in the east and centre of the fault zone that in the east is dominated by a few large moment release events that in the centre by a large number of small events both moment release rate peaks despite their different component seismicity are associated with high cumulative coseismic slip only the eastern peak is also associated with high stress drop it is also shallower and therefore any surficial interaction is less likely to be attenuated the surface projection of this peak is within 3 km of a mapped normal fault coincident with an alpine thrust front delineated by a major scarp of mesozoic limestone surface evidence of recent movement on this normal fault is only slight friable fault gouge is seen at a few localities displacement could not be determined because the limestone surfaces are deeply weathered and lack kinematic indicators however considering the whole fault zone as a cohesive entity and using a brune estimate of slip at the current moment release rate throughout the present extensional tectonic regime suggests a total vertical displacement of order 175 m similar to the elevation of the scarp

three dimensional seismic attenuation structure beneath the aegean region and its tectonic implication abstract the three dimensional attenuation structure beneath the aegean sea and the surrounding regions is determined by inversion of seismic intensity data a large number of seismic intensity data have been accumulated in a uniform scale in the aegean region where the seismic activity is much higher than that of the other mediterranean regions nearly 7000 seismic intensity data from 50 earthquakes that have occurred in these regions are used to determine seismic attenuation structure and source acceleration of the earthquakes the resultant structure reveals a remarkable contrast of attenuation in the top layer depth 0 40 km low q is dominant in the aegean sea while high q is dominant in the surrounding land areas except for the southwestern turkey the low q regions correspond to areas of neogene quaternary grabens where the high seismicity of shallow earthquakes appears in the upper mantle high q zones corresponding to the subducting african plate dominate along the hellenic arc the irregular shape of high q zones might reflect the split or disintegration of the african slab some low q spots corresponding to the distribution of volcanoes exist along the volcanic arc the low q spots might correspond to diapirs causing the subduction volcanism