changes in seismicity and stress loading on subduction faults in the kanto region japan 2011 2014 seismic activity has increased in the kanto region japan following the 2011 m9 0 tohoku earthquake we here reassess this increase up to june 2014 to show that normal omori like relaxation characterizes the activity on crustal faults as well as on the philippine sea plate but not on the deeper pacific plate there repeating earthquakes display a twofold rate of occurrence still ongoing in june 2014 as compared to the pre tohoku rate suggesting enhanced creep we compute the coulomb stress changes on the upper locked portion of the philippine sea plate which last ruptured in 1923 we find that this fault was little affected by either the coseismic the postseismic the accelerated creep or the 2011 boso silent slip event

structural analysis and interpretation of the surface deformations of the el asnam earthquake of october 10 1980 the el asnam earthquake of october 10 1980 represents the major seismotectonic event of these last decades in the west mediterranean area it has induced a large amount of surface breaks this earthquake reveals the importance of compressional phenomena that characterize nowadays the tectonics of north africa the tectonic analysis of surface rupture shows the complexity of the deformation mechanism the principal mechanism consists of the activation of a nw se trending thrust fault accompanied with a left lateral motion and with an intense deformation of the northwestern overthrusting block an accurate description of these deformations shows that for a large part the breaks geometry depends closely on the substratum structure finally the analysis of the dislocations on irrigation ducts just above the fault traces allowed a quantitative study of the deformation

earthquake mechanisms of the adriatic sea and western greece implications for the oceanic subduction continental collision transition summary we present 21 focal solutions magnitude 5 5 reliably computed by body wave modelling for the western hellenic arc from yugoslavia to the southern peloponnese mechanisms located within the aegean show normal faulting the t axis trending n s in the centre and parallel to the active boundary in the external part mechanisms associated with the keffalinia fault are consistent with dextral strike slip motion reverse mechanisms located along the active boundary are remarkably consistent and do not depend on the nature of the active boundary continental collision or oceanic subduction the consistency in azimuth of the slip vectors and of the gps velocity relative to africa all along the active boundary suggests that the deformation is related to the same motion the discrepancy between seismic energy release and the amount of shortening confirms that the continental collision is achieved by seismic slip on faults but the oceanic subduction is partially aseismic the northward decrease in velocity between continental collision and oceanic subduction suggests the continental collision to be a recent evolution of the active subduction

large scale patterns associated with tropical cyclogenesis in the western pacific abstract five characteristic low level large scale dynamical patterns associated with tropical cyclogenesis in the western north pacific basin are examined along with their capacity to generate the type of mesoscale convective systems that precede genesis an 8 yr analysis set for the region is used to identify and create composites for the five characteristic patterns of monsoon shear line monsoon confluence region monsoon gyre easterly waves and rossby energy dispersion this brings out the common processes that contribute to tropical cyclogenesis within that pattern which are described in detail a 3 yr set of satellite data is then used to analyze the mesoscale convective system activity for all cases of genesis in that period and to stratify based on the above large scale patterns it is found that mesoscale convective systems develop in all cases of genesis except one seventy percent of cases developed mesoscale convective systems at more than one time during the genesis period and 44 of

western hellenic subduction and cephalonia transform local earthquakes and plate transport and strain abstract focal parameters of local earthquakes in the region of the ionian islands of western greece are constrained with a temporary dense array of three component seismographs operated jointly offshore and onshore seismic deformation is documented to be confined to the east of the n20 e striking steep continental slope west of cephalonia island the right lateral cephalonia transform fault ctf inferred from large earthquakes the pre apulian continental material appears to be only deforming east of the transform fault where it is in upper plate position to the hellenic subduction east of the transform fault the transmission velocity tomography from local earthquakes compared in depth section with a previous marine reflection profile provides evidence in support of a shallow landward dipping boundary around 12 km deep under the ionian islands along which they may override the lower plate on either side of this interface local earthquakes occur with different focal mechanisms in support with its interpretation as the interplate under cephalonia island reverse faulting deforms the upper plate along nw se structures which may also be affected by left lateral bookshelf faulting small earthquakes show normal faulting along the western coast of cephalonia and its extension 20 km ssw the trace of the ctf as inferred from the occurrence of the large strike slip earthquakes another group of normal fault earthquakes locates in the lower plate from under cephalonia to zante just outboard of a possible change of interplate dip suggested from reflection seismics landward under the islands these normal fault earthquakes appear to coincide in position with that of the load imposed by the upper plate transported over them rather than occurring in an outer rise outboard the plate boundary and trench as observed in other subductions and attributed to the control by the flexural bending of the lower plate under the pull of the sinking slab interpretation has to consider several peculiar features of plate interaction in western greece with respect to a steady state model for major subduction zones in particular a fast deformation of the upper plate in front of an orogenically overthickened crust and of the southwestward push of extruding anatolia its transport which is the cause of the migration of the plate boundary rather than the roll back of a slab which has been proposed to be detached possibly a flat and ramp shape of the interplate the geometrical complexity of the shear limit across the ctf between subduction and collision and the nearby variation of the nature of the foreland crust

medium term precursors of strong earthquakes in southern italy abstract during the last two centuries the most intense earthquakes m 6 in southern italy have regularly occurred some years less than 5 after the main activations of the southern dinarides albania seismic zone to explain this interrelation we advance the hypothesis that the strong decoupling earthquakes at the adriatic dinarides collisional border cause a perturbation of the strain and stress fields which propagates through the adriatic plate with rates of some hundreds of km per year when this migrating perturbation reaches the opposite border of the adriatic plate it may induce seismic dislocations in the highly fractured southern apennines and calabrian arc statistical tests have been carried out to estimate the reliability of possible balkan seismic precursors of italian earthquakes the best results have been obtained with a precursor represented by the occurrence of at least one earthquake with m 6 5 or at least two shocks with m 6 0 assuming an alarm time of five years in this case the probabilities of a successful prediction i e the occurrence of an event with m 6 0 in southern italy within five years from the balkan precursor and of a non alarm are 83 and 10 respectively and the probability of obtaining these results by chance is very low less than 0 1

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

microseimicity and strain pattern in northwestern greece during a 7 week microearthquake experiment conducted in epirus akarnania and the ionian islands of western greece we located approximately 600 earthquakes with magnitudes between 2 and 4 2 no event was deeper than 40 km the seismicity cannot be clearly associated with any single fault except the lixourion right lateral fault located west of the ionian islands focal mechanisms of about 100 earthquakes show for a narrow band of earthquakes located along the coast ene wsw shortening consistent with the surface tectonics farther east focal mechanisms show nnw sse extension beneath the foothills of the pindus mountains which is unrelated to surface faulting but is consistent with the presently subsiding basins this strain pattern is seen far north and south of the lixourion fault and is similar to the one observed in the peloponnese it suggests that a large scale mechanism is responsible for the recent geodynamics of both the northwestern and southwestern aegean

horizontal crustal motion in the central and eastern mediterranean inferred from satellite laser ranging measurements four campaigns to acquire satellite laser ranging slr measurements at sites in the mediterranean region have been completed these measurements to the lageos satellite made largely by mobile systems cover a time span beginning in november 1985 and ending in june 1993 the range data from 18 sites in the central and eastern mediterranean have been simultaneously analyzed with data acquired by the remainder of the global laser tracking network estimates of horizontal motion were placed into a regional northern europe fixed kinematic reference frame uncertainties are on the order of 5 mm yr for sites having at least four occupations by mobile systems and approach 1 mm yr for permanently located sites with long histories of tracking the resulting relative motion between sites in the aegean exhibit characteristics of broadly distributed pattern of radial extension but at rates that are about 50 larger than those implied from studies of seismic strain rates based on seismicity of magnitude 6 or greater or across the region the motion estimated for sites in turkey exhibit velocity components associated with the westward motion of the anatolian block relative to eurasia these results provide a present day snapshot of ongoing deformational processes as experienced by the locations occupiedmore by slr systems less

late cenozoic deformation of the hellenide foreland western greece the late cenozoic structural evolution of western greece involved the shortening of mesozoic passive continental margin and cenozoic foreland basin sequences in a foreland propagating fold and thrust system and superimposed neotectonic deformation related to the development of an active island arc although the pre apulian zone has been regarded as the undeformed western foreland to the thrust belt three dimensional exposures in the ionian islands of kephalonia and zakinthos afford evidence of significant late neogene and quaternary shortening including thrusting on reactivated normal faults time relations and fault kinematics show that these structures are compatible with the westward migration of the locus of hellenide thrusting beyond its previously recognized limit and outer arc compression related to active subduction the presence of the pre apulian zone in the west contrasts with other aegean foreland areas where no such intermediate block lay between the thrust pile and old mesozoic oceanic crust consequently the pre apulian block took up continued hellenide shortening in the late miocene while oceanic crust was being overridden subducted in southern parts of the arc to the east the pre apulian zone subsequently overrode the ocean floored ionian sea during the late neogene the confusion in determining driving mechanisms for late cenozoic deformation in western greece and the apparent conflict between evidence for the age of initial subduction in different parts of the arc are explained by this model which is consistent with regional considerations including structuration in adjacent areas and important paleomagnetic rotations in the arc

trajectories of crustal deformation of western greece from gps observations 1989 1994 the geodynamic processes in the alpine mediterranean area are reflected in the recent crustal movements determined by satellite geodesy there is counterclockwise rotation of africa relative to eurasia with complex deformation in between we report repeated gps measurements carried out between se italy and the island of crete in the period 1989 to 1994 the data reveal distinct crustal motion of the central ionian islands and sw greece over the time span of five years western greece has moved 200mm 10mm to the sw relative to se italy and epiros the trajectories constructed from the repeated observations show that the boundary zone against the sites of no significant motion relative to south italy coincides with the kephalonia fault zone kfz this intense deformation accounts in part for the earthquakes that have frequently devastated the central ionian islands

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

quaternary tectonics in the gulf of patras western greece abstract air gun seismic and 3 5 khz profiling data from the gulf of patras western greece show that it is occupied by a small asymmetric graben with several geometric similarities to the larger scale graben in the gulf of corinth to the east major listric faulting characterizes the southern flank of the graben whilst the northern flank represents an associated rollover structure affected by antithetic and synthetic faulting the present phase of subsidence is of holocene age but buried growth faults suggest earlier subsidence in the gulf the average rate of subsidence through the holocene is estimated to be 10 mm year the gulf of patras graben together with the gulf of corinth graben and the megara basin represent a continuous system of wnw ese trending grabens in a broad zone of intense seismicity within the aegean domain individual grabens are offset and are interconnected by ne sw trending fault systems

some remarks concerning the paper the neotectonics of the aegean an alternative view by j a jackson g king and c vita finzi

paleomagnetic evidence for cenozoic clockwise rotation of the external albanides abstract a paleomagnetic study of 750 samples obtained from 55 late eocene to middle pliocene sedimentary sites demonstrates a clockwise rotation of about 45 of the external zones of albania this rotation occurred either in two phases of roughly equal amplitude during the early middle miocene and plio pleistocene or in a single phase with a clear acceleration of the movement during the plio pleistocene the good agreement of these results with those from southern albania and northwestern greece indicates that a large geographical area is involved in the rotation the active aegean compressive front thus extends much farther north than hitherto believed and the rotational pattern is not significantly distorted by the tectonic discontinuities recorded by geological studies the external zones of the albano hellenic belt appear to have rotated virtually as a single entity from the peloponnesos to northern albania over a deep decollement level probably involving the basement itself

establishment of a continuous gps network across the kephalonia fault zone ionian islands greece abstract we report on the establishment of a continuous gps network across the kephalonia fault zone kfz central ionian islands greece the kfz is an important segment of the boundary zone between the rapidly moving aegean microplate and the apulian platform italy repeated gps measurements carried out between the northern ionian islands and the island of crete have shown rates of crustal motion of the aegean reaching 35 mm a oriented sw relative to southern italy the kfz coincides with a maximum shear strain rate 180 nano strain a and a very high level of seismicity in order to monitor the ongoing deformation across the kfz and correlate the strain accumulation with earthquakes a continuous gps network has been installed operating at a sampling rate of 5 s this paper describes the instrumental set up the data logging strategy and first preliminary results

stress drop at the kephalonia transform zone estimated from the 2014 seismic sequence abstract the kephalonia transform zone ktz is a seismically active dextral transform fault decoupling the extensional deformed area of the ionian abyssal plain and the compressional deformed area of the mediterranean ridge we estimate a prominent steady state strain rate of 225 20 nstrain year across the ktz from the mean velocities of permanent global navigation satellite system gnss stations in east italy and west greece which confirms previous estimates based on the regional statistical seismicity and using the local gutenberg richter relation we investigate the energetic balance between stress accumulated as a consequence of the continuous dextral shear deformation and the average stress released by shallow seismicity if the maximum expected magnitude is mw 7 4 the estimated a and b parameters of the local gutenberg richter relation and the geodetically determined shear strain rate set an upper limit to the regional stress drop 0 4 mpa we verify these values by analyzing a seismic sequence on the ktz between january and february 2014 which culminated in the mw 6 09 event of jan 26 and the mw 6 14 event of feb 3 the estimated epicenters lie within a few kilometers from each other on the western side of the kephalonia island at a hypocentral depth 10 km the measured coseismic displacements of gnss stations in this area fit the expected surface dislocation which can be predicted for an elastic half space using the measured fault plane solutions as input if the hypocenters of the aftershocks are taken as indicator of optimal dextral shear stress orientation then a low regional deviatoric stress of 0 4 mpa that is comparable with the maximum regional stress drop estimated above is required for the coulomb stress to match the pattern of the aftershocks of the 2014 sequence as a consequence we conclude that the regional deviatoric stress and the seismically released shear stress are in close balance in the ktz seismic province

formulation of the conceptual model for the tectonic geomorphological evolution of an area five main rivers of greece as a case study abstract this paper associates the tectonic conditions of five rivers integrated drainage networks in northwestern greece for the purpose of formulating the conceptual model of its tectonic and geomorphological evolution the applied methodology consisted in the synthesis of elements from the fields of tectonics and geomorphology using suitable software and gis techniques and the correlation of fault and drainage network trends by the use of rose diagrams to reveal the structures and tectonic events affecting the different orders of the branches and its evolution the relation between morphology tectonics and the development of the drainage network enabled comparison across different areas the grouping of rivers and the identification of areas influenced by the same geodynamic regime in northwestern greece two main groups of rivers were distinguished flowing across areas featuring different tectonic conditions while a transitional zone between them was defined the stages of the area s tectonic and geomorphological evolution were identified with highlighting the definitive impact of tectonic structures on the configuration of the river routes e g the petousi souli fault which forms a natural boundary in the centre of the study area and new elements were added in view of the aforementioned northwestern greece is an independent transitional area in the geodynamic regime of the entire eastern mediterranean notably the methodology applied to these rivers may also be used in other areas thus constituting a standard tool for investigating the geodynamic regime and evolution

strain and rotation rate patterns of mainland greece from continuous gps data and comparison between seismic and geodetic moment release we processed data from 100 continuous gps stations to provide new insights into the crustal motion and deformation of central and western greece we used the derived velocity field to evaluate two dimensional strain and rotation rate tensors and we mapped the dilatation and maximum shear strain rates in central peloponnese and epirus we documented a 90 switch in the extension direction which can be explained on the basis of the plate boundary configuration evidence for an extended deformation pattern in central greece was found additionally we detected two pairs of shear belts one in akarnania nw peloponnese and one in north aegean we delineated two rotational domains that dominate the present day pattern moreover we saw no geodetic evidence for north anatolian fault growth toward central greece we translated the geodetic strain rates into rates of seismic moment release and compared them with earthquake catalog based moment rates in the central ionian sea the geodetic strain is completely released seismically which is indicative of a fully coupled seismogenic zone however for most of the study area the geodesy based moment rates are at least 2 times higher than the earthquake based rates we attribute this mainly to earthquake catalog representativity over the long term situation however for the gulf of corinth it is unrealistic to associate the high ratio of geodetic to seismic moment rates only to incompleteness of the earthquake catalog instead long term aseismic deformation must be an important mechanism accommodating a considerable portion of the strain budget especially at its western part

seismicity and geodynamics of western peloponnese and central ionian islands insights from a local seismic deployment abstract the tectonic setting of western peloponnese and central ionian islands greece is characterized by the subduction of the oceanic african plate beneath the aegean micro plate the transition from subduction to continental collision in northwestern greece is accommodated by the right lateral cephalonia transform fault in this work we exploit the recordings of a temporary seismic network composed of 15 stations operating from july 2016 until may 2017 to investigate the complex deformation of this region our local network fills in a major observational gap in one of the most tectonically active regions of the hellenic arc we detected and located more than 1200 local earthquakes and constrained five 1d optimum local velocity models the relocated seismicity including the aftershock sequence that followed the october 2018 mw 6 7 earthquake offshore zakynthos and associated focal mechanisms constrained for the major earthquakes point out a complex crustal deformation we propose a clockwise rotation of the ionian akarnania block accommodated by major marginal strike slip fault zones that appear segmented along their strike additionally left lateral motion is observed on the kyllini cephalonia fault along a north west direction finally the seismicity recorded in north cephalonia offshore myrtos and fiskardo suggests that the cephalonia transform fault is a large deformation zone where secondary wnw striking sinistral strike slip faults occur

the continuity of active fault systems in greece summary evidence from geomorphology the distribution of large earthquakes and geodetic measurements suggests that the active faulting in mainland greece and the north aegean sea is concentrated into a small number of discrete linear zones that bound relatively rigid blocks on land the zones are most clearly identified where the faulting is associated with large escarpments particularly in hard footwall rocks the zones can become indistinct and diffuse near their ends sometimes because they enter high unstable topography where landsliding obscures the fault morphology but mostly because the extension rates decrease along strike as a consequence of the relative rotation of the blocks they bound the main graben systems of chalkidiki southern thessaly and the north gulf of evia all seem to connect with the strike slip faulting in the offshore aegean and to die out in the west a configuration related to clockwise rotations in east central greece by contrast the gulf of corinth which is the fastest opening graben system in greece opens more rapidly in the west than the east both these features of the gulf of corinth are consequences of the motion of the south aegean and peloponnese as a single block late pliocene and quaternary geology and geomorphology indicate that the boundaries of the rigid blocks in central greece have changed over that time with faulting migrating into the hanging walls sometimes changing in orientation these changes are probably related to the way faulting in the seismogenic layer adapts to block rotation so as to maintain the general features of a velocity field that is controlled by larger scale effects such as buoyancy forces and the seaward migration of the subducting slab beneath crete the image of greece as a mosaic of rigid blocks whose boundaries change with time is a useful framework for seismic hazard evaluation but we emphasize that some moderate sized earthquakes do occur away from the main fault zones within the relatively rigid blocks and especially near their diffuse ends

topographic site effects and hvsr a comparison between observations and theory we present a comparison between observed and predicted amplification on a topographic feature our data come from an ad hoc experiment carried out during the summer of 1989 in epire northern greece ten digital autonomous three component stations recorded a total of 68 small earthquakes as these data were inadequate to compute empirical transfer functions using the standard spectral ratio ssr technique we explored the possible use of horizontal to vertical spectral ratios hvsr first we compare hvsr computed from theoretical transfer functions for incident p sv and rayleigh waves with the horizontal transfer function for each incidence type second we compute hvsr for our weak motion data set and show that the results are stable with a scatter not larger than that usually accepted in ssr studies we observe significant differences between n s and e w motion when we compare hvsr with theoretical transfer functions we obtain a better agreement for sv motion than for sh motion amplification levels are similar between hvsr and predicted amplification even for the sh case this suggests that discrepancies that have been signaled for the topographic amplification between observations and predictions could be due to site effects being present in the reference station used to computed ssr our results support the use of hvsr to determine topographic site effects thus hvsr may have a large potential to evaluate site effects in a wider variety of geological conditions than previously thought without the shortcomings of ssr finally we show that hvsr computed from noise recordings gives a reasonable estimate of hvsr computed from weak motion data although this conclusion should be better substantiated our preliminary results are encouraging

mapping an earthquake induced landslide based on uav imagery case study of the 2015 okeanos landslide lefkada greece abstract on november 17 2015 07 10 utc an earthquake of mw 6 5 induced slope failures mainly at the western part of the island of lefkada ionian sea greece the most characteristic one is the okeanos site deep seated landslide near village athani that affected the man made environment part of the site including a dirt road moved downwards along the coastal cliff and a luxury hotel suffered heavy damage the goal of this study is to map in detail the okeanos landslide and to provide relevant quantitative data i e structural data and volume of both the accumulated and removed material in order to achieve this a comparison between pre earthquake and post earthquake point clouds generated from aerial imagery and uav acquired photos took place using structure from motion the steep coastal cliff site was surveyed in detail even in areas that are difficult to approach results from this study show that the total landslide area covers a surface of 36 000 m2 while a removed volume of 93 000 m3 of landslide material was evaluated using change detection techniques in addition fieldwork and survey data revealed that the sliding surface was a pre existing fault surface upon which the geological material moved downwards the coastal cliff the sliding surface dips west and is exposed along a 115 m long and 25 30 m high section scarp as a conclusion this study underlines the importance of a thorough geological study in order to identify landslide prone areas prior to any building activity and shows that a uav survey is capable to provide adequate information during a post earthquake field survey for co seismic landslide mapping and modeling

tectonics and sedimentation in the gulf of corinth and the zakynthos and kefallinia channels western greece abstract single channel seismic reflection profiling data are presented from the gulf of corinth and from the continental margin outside the gulf of patras different tectonic styles are exhibited in the two regions the gulf of corinth is occupied by a complex asymmetrical graben structure with major faults trending nearly perpendicular to the local tectonic zones of the internal hellenides the gulf is interpreted to have formed during the quaternary in response to approximately north south extensional stress the deep floor of the gulf is underlain by a sequence of turbidites up to 1 km thick affected by normal growth faulting that extends up to the sea floor the sea areas inside the ionian islands of zakynthos and kefallinia zakynthos and kefallinia channels occupy a broad structural depression that trends parallel to the local tectonic zones of the external hellenides and is situated on the continental side of the strophades continental margin rise the channels contain local nw se trending structural basins zakynthos and kefallinia basins whose geometry is controlled by reverse faults or thrusts with associated diapirism in triassic evaporites hydra bank is interpreted as a tilted fault block with a diapiric core and its faulted western margin can be traced into the zone of thrusting and diapirism in southeast kefallinia at the boundary between the ionian and pre apulian paxos zones of the external hellinides the zakynthos and kefallinia structural basins are filled with a variety of sediments including prodeltaic deposits in front of the modern delta complex of the acheloos river slumped masses and debris flow deposits and in the zakynthos basin occasional turbidites the boundary separating zones of extensional and compressional focal mechanisms for shallow earthquakes crosses the gulf of patras the inner part of which exhibits wnw ese trending graben tectonics apparently related to the gulf of corinth tectonic province onshore neotectonic studies around the gulf of patras are required in order to understand the nature and cause of the westward tectonic transition from wnw ese graben structures in the gulfs of corinth and patras to nw se oriented zones of subsidence with associated compressional tectonics and diapirism in the zakynthos and kefallinia channels

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

neotectonic evolution of northwestern continental greece the post miocene sedimentary and structural evolution of nw continental greece changes from west to east

the kephalonia transform fault and the rotation of the apulian platform evidence from satellite geodesy this paper describes a collaborative gps project to determine recent crustal movements and deformations across the ne ionian sea this region is characterized by rifting in the african foreland pelagian sea subduction along the calabrian and west hellenic arcs rotation of the italian peninsula and distributed normal faulting in central greece from gps campaigns on the ionian islands and in nw greece performed in 1989 and 1991 a kinematic field is deduced which is controlled by the deep trough following the nw coast of kephalonia island it is concluded that this prominent bathymetric feature resembles an active fault system kephalonia fault which has the signature of a right lateral transform fault

the 1953 earthquake in cephalonia western hellenic arc coastal uplift and halotectonic faulting summary geomorphological marine biological and radiometric data in combination with earlier reports reveal that the m 7 2 1953 cephalonia earthquake the most destructive but least studied earthquake in greece this century was associated with a 0 3 0 7m quasi rigid body uplift and westward tilting of the central part of the island another palaeoseismic event around 1500 yr bp associated with coastal uplifts was also identified structural data indicate that the 1953 uplift is bounded by two subparallel east dipping major reverse faults and corresponds to a piston like motion this structurally unusual pattern of seismic deformation is detached from the deformation of the basement conspicuously a thrust and different from the long term deformation pattern of the area it is probably due to the particularities of salt tectonics a 1500m thick salt layer acts as a regional dccollement while thinner layers are sandwiched between the carbonate thrust sheets that compose the overburden and reduce their friction during fault movement this crustal anisotropy is responsible for the observed anomalous attenuation of seismic waves during the 1953 and historical earthquakes the 1953 seismic surface deformation mimics long term halotectonic patterns but is not directly indicative of the regional stress field for it reflects uplift induced stresses only

some relationship between van seismic electric signals ses and earthquake parameters abstract a possible correlation between ses seismic electric signals of the van method characteristics and earthquake parameters is investigated for the period january 1 1983 december 31 1994 for western greece during this period there were total of 55 earthquakes of mb 5 0 in the region of the so called selectivity maps of the ioannina ioa and pirgos pir van stations cmt solutions are available for 29 of these earthquakes eighteen were preceded by ses at ioa and eleven at pir none of them was preceded by simultaneous ses at both stations the main results are as follows 1 the direction of the ses vector at ioa is correlated with the focal position of predicted earthquakes although nearby earthquakes often have ses with dissimilar vector directions 2 the ses of all nine thrust events of the 29 earthquakes were observed at ioa but their vector direction was not unique 3 eleven earthquakes in the zone west of kefallinia to peloponese preceded by ses at pir were of the strike slip type with varying degrees of normal component the vector direction of ses at pir for these earthquakes was predominantly westward 4 the source mechanism changed from largely strike slip type to thrust type in the above zone at the end of 1987 and this coincided with a shift in the sensitive site from pir to ioa indicating a possible correlation between the source mechanism and selectivity characteristics of van stations

a microearthquake study in the gulf of patras region western greece and its seismotectonic interpretation summary the seismicity of the gulf of patras region was monitored from 1983 may to 1984 april by a six station microearthquake network with 30 km aperture over 650 events were located using the revised version of the hypo71 computer program for determining hypocentral locations of these a subset of 73 well located events was identified for detailed study analysis of these 73 events reveals a local pattern of seismicity with two main features firstly a gap in seismicity in the central and western parts of the gulf despite the local presence of active faulting affecting the seabed secondly a zone of high seismicity in the northeast part of the gulf where offshore seismic surveys reveal a zone of intense structural complexity a northeast dipping diffuse zone of seismicity extending to a depth of about 25 km has been identified in the northeastern corner of the gulf centred on the rio antirrio channel between the gulfs of patras and corinth it is postulated that the active faults in the central part of the gulf which are apparently aseismic are linked via a shallow decollement surface under the gulf to a deep wnw ese trending fault zone defining the southern margin of the corinth graben and extending westwards to trichonis lake the dipping zone of seismicity is related to the latter fault zone and aseismic faulting in the gulf of patras is attributed to the shallow surface of decollement into which the faults sole a transfer fault zone trending approximately ne sw is postulated to account for the offset of the corinth and patras grabens

first paleomagnetic evidence for rotation of the ionian zone of albania a paleomagnetic study of 170 samples obtained from 15 sites from cretaceous eocene and oligocene sedimentary rocks documents a 45 clockwise rotation of the albanian ionian zone this rotation is certainly post eocene and most probably post oligocene these results show that the entire ionian zone has undergone a semi rigid rotation about a pole of rotation situated farther north than previously believed

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

rupture process and aftershocks relocation of the 8 june 2008 mw 6 4 earthquake in northwest peloponnese western greece on 8 june 2008 at 12 25 gmt an m w 6 4 strong earthquake occurred in the area of northwest peloponnese western greece causing the death of two people and extensive damage to the surrounding area the main event and its aftershocks were recorded by one nationwide and three regional networks equipped with three component broadband seismometers initial locations of the earthquake sequence comprising 438 aftershocks showed a linear northeast southwest trend and that the mainshock was located at 22 km depth after the relocation using catalog and differential travel times most events form three distinct clusters at depths 15 25 km moment tensor solutions for the main event and its largest aftershocks exhibited a pure strike slip mechanism with one nodal plane orientated northeast southwest in accordance with the relocated seismicity a parallel nonnegative least squares inversion technique utilizing multiple time windows was used to derive the spatiotemporal slip distribution of the main event the resulting slip distribution model revealed a large slip patch maximum slip 150 cm between 10 and 20 km depth at the northeast part of the fault that also coincides with the area that suffered most of the damage another patch exhibiting smaller amounts of slip 20 50 cm is located to the southwest direction at the same depth range and smaller patches exist at 25 30 km depth most aftershocks are located in areas of low slip 25 cm filling the regions of slip deficit the 8 june earthquake occurred at an area where no previous seismological or other observations indicated the existence of a seismogenic fault at that depth and with this strike this and the fact that the event nucleated in the middle to lower crust may be interpreted as the reactivation of a fault structure that was inherited from previous tectonic phases

the strain pattern in the western hellenic arc deduced from a microearthquake survey summary than loo0 earthquakes recorded during 7 weeks in 1986 in the peloponnese and surrounding areas show shallow seismicity spread over a wide area bounded by the hellenic trench the highest level in the energy release is for clusters located along the hellenic trench where changes in the morphology are seen a few clusters are also observed as at the intersection between the gulf of corinth and the gulf of patras near the lake trikhonis or between kythira and crete in the peloponnese the shallow earthquakes do not define single faults but are diffusely distributed a higher concentration and a deepening of the foci within the whole crust towards the west seem to reflect a higher strain rate there fault plane solutions exhibit a scattered pattern for earthquakes shallower than 11 km but for earthquakes deeper than 11 km they show some consistency in the orientation of p t and b axes gently dipping nodal planes are seen all over the peloponnese with the conjugate vertical plane striking in various directions and with no consistency in the sense of motion these earthquakes are located between 8 and 18 km deep and could reflect a decoupling between the lower and the upper crust reverse faulting is seen in the gulf of kefallinia and the western peloponnese the p axes trend ne sw to e w normal faulting is seen in the gulf of corinth and in central peloponnese with the t axes trending n s and in the southern peloponnese where the t axes trend nw se the deformation over the western hellenic arc revealed by fault plane solutions of earthquakes with depth between 11 and 40 km appears to be the superposition of two phenomena first throughout the aegean crustal extension with orientation roughly parallel to the trench dominates with crustal shortening and subduction along the aegean arc superimposed on this is a more local effect of the collision between the aegea and apulia which seems to induce horizontal compression roughly perpendicular to the aegean arc west of the peloponnese and epirus the compression due to this decays eastward at a distance comparable with the width of the collision zone the deepening of the brittleductile transition is likely to be due to an increase of the strain field towards the ionian islands

late quaternary evolution of the gulf of patras greece tectonism deltaic sedimentation and sea level change abstract the gulf of patras is an actively subsiding late cenozoic graben in western greece that receives deltaic sediment from the large acheloos and evinos rivers the late quaternary sedimentation history of the gulf is interpreted from 3 5 khz profiles numerous short cores and airgun seismic profiles a widespread unconformity represents the isotopic stage 2 marine lowstand when the gulf was subaerially exposed subsequent deltaic progradation and associated coastal transgression was greatest during the 13 10 5 ka slowdown in sea level rise and the period of stable sea level since the mid holocene switching of delta distributaries can be related to the known evolution of the subaerial parts of the deltas the stage 2 unconformity provides a datum for quantitative determination of rates of subsidence the central graben is subsiding at rates of 3 5 mm yr rates in the northern part of the gulf average 1 2 mm yr this is consistent with a listric faulting model for the origin of the modern patras graben

intermediate depth seismicity in the aegean defined by teleseismic data the most reliably located intermediate depth earthquakes in the aegean area selected from the international seismological centre catalogue deepen towards the internal part of the hellenic arc and reach a maximum depth of 150 km during the last 20 years most have occurred at the eastern and western ends of the arc and very little activity is found in the middle area north of crete the seismic zone defines a contorted slab of lithosphere in the western part a very shallow dipping seismic zone extends 200 km northeast from the trench and then steepens abruptly at depths of about 50 80 km eventually reaching dips of 45 the 100 km and 150 km isodepth contours are not parallel to the hellenic trench in the western part the geometry of the slab is more consistent with a south southwestward translation of the aegean arc with respect to the african plate than with a rotation around a pole located close to the aegean region

closure of the africa eurasia north america plate motion circuit and tectonics of the gloria fault we examine the closure of the current plate motion circuit between the african north american and eurasian plates to test whether these plates are rigid and whether the gloria fault is an active transform fault we also investigate the possible existence of microplates that have been previously proposed to lie along these plate boundaries and compare the predicted direction of motion along the african eurasian plate boundary in the mediterranean with the direction of slip observed in earthquakes from marine geophysical data we obtain 13 transform fault azimuths and 40 3 m y average spreading rates 34 of which are determined from comparison of synthetic magnetic anomaly profiles to 140 observed profiles slip vectors from 32 earthquake focal mechanisms further describe plate motion detailed magnetic surveys north of iceland provide 11 rates in a region where prior plate motion models had few data magnetic profiles north of the azores triple junction record a rate of 24 mm yr 4 mm yr slower than used by prior models gloria and sea beam surveys accurately measure the azimuths of seven transform faults our plate motion model fits six of the seven within 2 two transform faults surveyed by gloria side scan sonar lie near famous area transform faults a and b and give azimuths 13 clockwise of them because recent studies show that short offset transforms such as transforms a and b are in many places oblique to the direction of plate motion we exclude azimuths from transforms with less than 35 km offset the best fitting and closure enforced vectors fit the data well except for a small systematic misfit to the slip vectors on right lateral slipping transforms slip vectors tend to be a few degrees clockwise of plate motion and mapped fault azimuths whereas on left lateral slipping transforms slip vectors tend to be a few degrees counterclockwise of plate motion and mapped fault azimuths we search the long eurasia north america boundary for evidence of an additional plate but find no systematic misfits to the data in particular if a spitsbergen plate exists and moves relative to eurasia its motion is less than 3 mm yr an africa eurasia euler vector determined by adding the eurasia north america and africa north america euler vectors is consistent with the gloria fault trend and with slip vectors from eastern azores gibraltar ridge focal mechanisms a small circle centered at the africa eurasia closure enforced pole fits the trace of the gloria fault the model in which closure was enforced predicts 4 mm yr slip across the azores gibraltar ridge and west northwest convergence near gibraltar 45 more oblique than suggested by a recent model based on compressive axes of focal mechanisms moreover our model predicts directions of plate motion that agree well with northwest trending slip vectors from thrust earthquakes between gibraltar and sicily because closure enforced vectors fit the data nearly as well as the best fitting vectors we conclude that the data are consistent with a rigid plate model and with the gloria fault being a transform fault

the landscape geometry and active tectonics of northwest greece when a region is tectonically deformed its geometry changes some of these changes produce easily identified and often readily datable morphological features such as regions of rapid uplift and subsidence sediment ponds or river terraces these features are usually secondary to the main active structures and consequently do not provide information about them directly we show however that simple models using boundary element methods can be adapted to relate the evolution of these minor features to motion on major structures this adds substantially to the information available to determine motion on such features in this paper we apply the technique to northwest greece we show that in addition to the long recognized compressional component of motion in epirus a substantial left lateral strike slip component of motion must be present the modeling allows us to identify a regional slip vector of n275 e this slip vector suggests that the plate configuration assumed by previous workers must be modified a new configuration is proposed that remains consistent with the data used for earlier interpretations and our new data it is proposed that the medina wrench is a significant active structure and that a period of quiescence explains the low seismic activity at present the plate configuration and angular rotation rates that we suggest require that the gulf of arta is associated with a triple junction using the slip vectors we have defined for the plates meeting at this junction we model the regions of uplift and subsidence in the region the ability of this model to explain many features associated with the gulf provides assurance that our overall tectonic model is correct

transition from collision to subduction in western greece the katouna stamna active fault system and regional kinematics transition from subduction to collision occurs in western greece and is accommodated along the downgoing plate by the kefalonia right lateral fault that transfers the hellenic subduction front to the apulian collision front here we present an active tectonic study of aitolo akarnania western greece that highlights how such a transition is accommodated in the overriding plate based on new multi scale geomorphic and tectonic observations we performed an accurate active fault trace mapping in the region and provide evidence for active normal and left lateral faulting along the katouna stamna fault ksf a 65 km long nnw striking fault system connecting the amvrakikos gulf to the patras gulf we further show that the cenozoic hellenide thrusts located west of the ksf are no longer active either in field observation or in gps data leading us to propose that the ksf forms the northeastern boundary of a rigid ionian islands akarnania block iab cosmic ray exposure measurements of 10be and 36cl were performed on a quaternary alluvial fan offset along the ksf 50 m left lateral offset a maximum abandonment age of 12 14 ka for the alluvial fan surface can be determined giving an estimated ksf minimum geological left lateral slip rate of 4 mm year 1 in agreement with high gps slip rates 10 mm year 1 despite this high slip rate the ksf is characterized by subdued morphological evidence of tectonic activity a gypsum breccia bedrock and a low level of seismicity suggesting a dominantly creeping behavior for this fault finally we discuss how the iab appears to have been progressively individualized during the pleistocene younger than 1 5 ma

an analog experiment for the aegean to describe the contribution of gravitational potential energy the southern aegean seafloor exhibits clear evidence of internal deformation stretching as shown by tectonics seismology and space geodesy we use an analog three layer laboratory experiment of sand silicone putty and honey to investigate the deformation of the southern aegean lithosphere the model is installed in a box and confined by a vertical wall we open a gate in the wall and observe the deformation of the two upper layers due to buoyancy forces the general pattern of the deformation of the southern aegean is found in the analog model we observe the formation of an arc spreading outward with time the extension is radial in the inner part but parallel to the arc in the external part and of comparable importance at both ends of the gate we observe strike slip motion dextral in the western part sinistral in the eastern part rotation clockwise in the western part counterclockwise in the eastern part of up to 40 is seen on both sides of the gate but is also present with a smaller amplitude far in the internal region partially due to distributed shear the spreading is associated with the thinning of the two upper layers and affects a region of dimensions comparable to the length of the free boundary this spreading does not propagate inward with time some pieces of material located near the active boundary remain undeformed during the experiment

the april 2007 earthquake swarm near lake trichonis and implications for active tectonics in western greece abstract we investigate the properties of the april 2007 earthquake swarm mw 5 2 which occurred at the vicinity of lake trichonis western greece first we relocated the earthquakes using p and s wave arrivals to the stations of the hellenic unified seismic network husn and then we applied moment tensor inversion to regional broad band waveforms to obtain the focal mechanisms of the strongest events of the 2007 swarm the relocated epicentres cluster along the eastern banks of the lake and follow a distinct nnw ese trend the previous strong sequence close to lake trichonis occurred in june december 1975 we applied teleseismic body waveform inversion to obtain the focal mechanism solution of the strongest earthquake of this sequence i e the 31 december 1975 mw 6 0 event our results indicate that a the 31 december 1975 mw 6 0 event was produced by a nw se normal fault dipping to the ne with considerable sinistral strike slip component we relocated its epicentre i using phase data reported to isc and its coordinates are 38 486 n 21 661 e ii using the available macroseismic data and the coordinates of the macroseismic epicentre are 38 49 n 21 63 e close to the strongly affected village of kato makrinou b the earthquakes of the 2007 swarm indicate a nnw sse strike for the activated main structure parallel to the eastern banks of lake trichonis dipping to the ne and characterized by mainly normal faulting occasionally combined with sinistral strike slip component the 2007 earthquake swarm did not rupture the well documented e w striking trichonis normal fault that bounds the southern flank of the lake but on the contrary it is due to rupture of a nw se normal fault that strikes at a 45 angle to the trichonis fault the left lateral component of faulting is mapped for the first time to the north of the gulf of patras which was previously regarded as the boundary for strike slip motions in western greece this result signifies the importance of further investigations to unravel in detail the tectonics of this region

the neotectonics of the aegean an alternative view minor reverse faults in widely dispersed neogene outcrops in the central aegean have led several people to suggest that the regional extension which started in the lower pliocene or earlier was interrupted by short periods of compression the durations of these postulated compressional episodes are short compared to the time scale on which convective forces acting on the base of the lithosphere can change thus possible mechanisms for driving such motions are limited in this paper we offer alternative explanations for these observations and in particular show that these apparently compressional episodes are probably not regional in extent and may not be truly compressional in origin in some places they are more likely to be a consequence of the considerable rotation that is found in extensional terranes the plio quaternary paleogeography of the central aegean is satisfactorily explained by uplift in the footwall blocks of normal faults and does not require regional compression studies of the faulting associated with recent large earthquakes suggest that the sort of microtectonic analysis which is typically carried out on small faults in surficial sediments is more likely to reflect the internal deformation of blocks bounded by major fault structures than be a reliable indicator of regional stress patterns

microseismicity and focal mechanisms at the western termination of the north anatolian fault and their implications for continental tectonics summary for seven weeks a temporary network of 68 seismological stations was operated in central greece in the region of thessaly and evia located at the western termination of the north anatolian fault system we recorded 510 earthquakes and computed 80 focal mechanisms seismic activity is associated with the ne sw dextral north aegean fault or with very young e w striking normal faults that are located around the gulf of volos and the gulf of lamia the important nw se striking faults bounding the pilion or the basins of larissa and karditsa are not seismically active suggesting that it is easier to break continental crust creating new faults perpendicular to the principal stresses than to reactivate faults that strike obliquely to the principal stress axes

seismicity and seismotectonics in epirus western greece results from a microearthquake survey during a twelve month passive tomography experiment in epirus in northwestern greece a total of 1368 microearthquakes were located the most accu rately located events and focal mechanisms are used here to understand the seismo tectonics of the area the seismicity shows a clear association with the main previously defined deformation zones a total of 434 well defined focal mechanisms were also used for the determination of the stress pattern in the area the computed stress field pattern is quite complex close to the surface and almost homogeneous at depths below 15 km for these depths the stress field is purely compressional in a west southwest direction whereas for shallow depths it is transpressional or even extensional for some smaller areas the abrupt change in the stress pattern which occurs as depth increases suggests the existence of a detachment surface which is provided by the evaporites that have intruded into the upper layers through the thrust zones the presence of the evaporites and their lateral extent is mapped by the seismicity distribution and con firmed by seismic tomography based on the findings we estimate a possible total evaporite thickness of almost 10 km at least for the central part of the study area such a result is important for the oil exploration efforts that have just started in epirus

microearthquake seismicity and active tectonics of northwestern greece we carried out a microearthquake survey lasting for six weeks in northwest greece using 18 portable seismograph stations to examine a region in which normal and thrust faulting have been reported in close proximity to one another with this array we located 148 events and determined fault plane solutions for eight events using only rays radiated upwards the seismicity of the region is diffuse with events extending to depths of nearly 30 km and there is a minimum in activity near a depth of 15 km the fault plane solutions exhibit a wide spectrum of fault types and orientations and are not consistent with simple zones of shortening or extension neither tractions applied to the edges or bottom of the region nor deviatoric stresses that compensate for lateral variations in crustal thickness can account for the variety of fault plane solutions we think that the complicated behavior is a manifestation of inhomogeneous deformation due at least in part to a pre existing complicated juxtaposition of structures and formations

microearthquake seismicity and fault plane solutions in the southern aegean and its geodynamic implications summary seismicity mi 3 5 in the southern aegean located using data collected during seven weeks of recording by a temporary network of seismological stations largely follows the hellenic arc the sea of crete is nearly aseismic and only little activity is located south of the hellenic trench within the african plate focal mechanisms exhibit reverse faulting in the external part of the arc and normal faulting inside it this normal faulting indicates n s extension in the northern aegean the gulf of corinth the cyclades and dodecanese islands but nw se extension in southern peloponnese and western crete and e w extension in eastern crete this non uniform strain pattern suggests that the aegean region not only extends in a n s sense with the hellenic arc moving south westward relative to the eurasian plate but also by e w extension of its southern margin so that there is a net divergence of material

reflection seismic study across the continental shelf of baba burnu promontory of biga peninsula northwest turkey abstract seismic and structural characteristics of the continental shelf of baba burnu promontory of biga peninsula northwest turkey were investigated by 67 km of multi channel seismic reflection survey interpretation of the seismic data indicates that the faults may be divided into two groups i in the southern area almost an e w trending major listric normal fault zone and subsidiary faults formed first and later a strike slip fault on the hanging wall of the major fault formed ii in the northern area a number of spatially developed parallel faults with major strike slip components are seen we propose that the gulf of edremit is a fault bounded basin which began to form in association with the generation of the e w trending faulting phase during the late miocene early pliocene

length scales for continental deformation in convergent divergent and strike slip environments analytical and approximate solutions for a thin viscous sheet model the deformation of a thin viscous layer that has a moving boundary is investigated for comparison with zones of deformation in the continental lithosphere exact analytical solutions for the case of a newtonian fluid and approximate solutions for the case of fluid with power law rheology show that when the imposed velocity vector is normal to the boundary congressional or extensional regime the deformation field decays away from the boundary with a characteristic length scale 1 3 to 1 10 the wavelength of the imposed boundary velocity distribution for n between 1 and 10 where n is the stress strain exponent in the rheology in contrast when the imposed velocity vector is parallel to the boundary transcurrent regime the length scale of the deformation field is approximately 4 times smaller in each case these length scales decrease approximately as n the difference in length scales arises even in the absence of any buoyancy forces acting on thickened or thinned crust such forces would modify the ratio of length scales but not sufficiently to affect this result

strong tsunami impact on the bay of aghios nikolaos and its environs nw greece during classical hellenistic times abstract this paper presents for the first time detailed geomorphological sedimentological geoarchaeological geophysical and geochemical evidence of a strong tsunami impact on the bay of aghios nikolaos and its environs nw greece during classical hellenistic times tsunamigenically dislocated beachrock slabs found on top of the santa maura beach ridge complex are closely interrelated to adjacent coarse grained washover fan deposits encountered in vibracores and detected by earth resistivity measurements based on detailed topographic surveys and geomorphometric investigations it was possible to localize areas of high intensity overflow underwater studies revealed that the central and northern parts of the former plaka beach ridge were completely destroyed by tsunami impact loose littoral deposits were flushed into the bay of aghios nikolaos and mega blocks of the underlying beachrock structure were dislocated landwards tsunami landfall occurred all along the eastern and northern shores of the bay where deposits partly weathered and associated to archaeological findings were found runup was estimated to minimum values between 2 3 m and 4 6 m a s l crosschecking the results of radiocarbon analyses with archaeological ages from five sites allowed to date the strong tsunami event to the time period between 395 cal bc and 247 cal bc due to the funnel like contour of the coastline the area is extremely sensitive to tsunami events of mid to high magnitude and high frequency

tertiary geodynamical evolution of northwestern greece paleomagnetic results abstract paleomagnetic results have been obtained from 29 sites sampled in lower to upper oligocene flysch sections of the ionian zone in northwestern greece they indicate a clockwise rotation of about 45 of the entire region a comparison with previously published results relative to both younger and older formations shows that this rotation has occurred in two phases of comparable amplitude one during middle miocene and the other during pliocene and quaternary separated by a period of at least 7 ma during which no significant rotation has occurred no major rotation has occurred during the entire paleocene and eocene stages this large measured rotation implies a horizontal displacement of at least 100 km in epirus possible mechanisms involving a rotation of the nappe sheets rotation of the basement or a combination of the two are discussed the two phases of paleomagnetic rotation can be correlated with the tertiary and quaternary calc alkaline volcanic activity in the aegean sea a palinspastic reconstruction shows that the orientation of the major structures now striking n155 was almost east west in the middle miocene at the epoch of their formation

palaeomagnetic evidence from pelagic limestones for clockwise rotation of the ionian zone western greece abstract on the basis of a pilot study of all the major carbonate lithologies in the ionian zone of western greece the upper part of the upper senonian to upper eocene microbreccious limestones formation was selected as the most suitable facies for a detailed regional palaeomagnetic study the 51 sites sampled are situated on flanks of anticlines or monoclines which post date the acquisition of the characteristic remanent magnetization the regional folding occurred during post late eocene emplacement of nappe sheets which had undergone decollement on triassic evaporitic horizons the palaeomagnetic directions after correction for deviations of local fold axis orientation have a regional significance after this correction the mean palaeodeclination is about 35 e relative to the geographic pole with respect to the early tertiary african pole position these palaeodeclinations indicate an apparent 38 clockwise rotation of the nappe sheets the palaeoinclinations support a palaeogeographic model locating the carbonate sediments of the ionian zone on the northeastern margin of the adriatic promontory of the african plate the total rotation implied by the palaeodeclination data is possibly due to a combination of two different mechanisms 1 1 rotation of the nappe sheets during overthrust and emplacement during the main mid miocene compressional phase of deformation 2 2 rotation of the ionian zone basement and nappes associated with extension in the aegean basin during the last 13 m y

the november 17th 2015 lefkada greece strike slip earthquake field mapping of generated failures and assessment of macroseismic intensity esi 07 abstract on november 17 2015 a strong shallow earthquake mw 6 5 occurred on the island of lefkada along a n20 5 e east dipping strike slip fault with right lateral sense of slip the event triggered environmental effects that were mainly mapped at the western part of the island while moving towards the eastern part the severity of the earthquake induced failures decreased the most characteristic geological effects that were triggered by the earthquake were slope failures including rock falls rock slides and landslides the spatial density of the failures follows an exponential increase with slope angle and decreases for values larger than 55 small size liquefaction phenomena such as sand craters and ejection of fine grained sand through ground cracks were documented at the coastal area of vassiliki the epicentral intensity was assessed based on the definitions of environment seismic intensity scale as viii esi 07 and the macroseismic epicenter viii up to ix was located at the coastal area of egremnoi west of athani village south lefkada in addition comparing the severity of earthquake induced failures on the main road network triggered by the 2003 and 2015 events it is concluded that the behavior of the protection measures such as fences and walls could be generally characterized as satisfactory on the contrary the similarity of the structural failures triggered by the 2003 event with the ones triggered by the 2015 earthquake documented at the port of vassiliki indicates that the post 2003 constructed port facilities failed to guarantee the functionality of the port of vassiliki

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

moment tensor inversion of the 1983 january 17 kefallinia event of ionian islands greece summary the source parameters of the recent 1983 january 17 ionian island event are obtained by the inversion of body waves an optimum source depth of 8 km is determined and the source parameters of the major double couple are strike 60 dip 47 rake 174 and seismic moment m0 7 3 1025 dyne cm this mechanism implies a strike slip dextral fault with a small thrust component this solution ascertains the existence of a transform fault connecting the northwestern edge of the hellenic are with the compressional zone which is produced by the collision of the apulian plate with the eurasian plate along the adriatic north ionian coast this right lateral strike slip fault probably terminates the hellenic subduction zone

3d crustal structure from local earthquake tomography around the gulf of arta ionian region nw greece during summer of 1995 local seismicity was recorded in the area around the gulf of arta in northwestern greece by a dense temporary seismic network of the 441 local events observed at 37 stations 232 well locatable events with a total of 2776 p phase readings were selected applying the criteria of a minimum of 6 p observations and an azimuthal gap less than 180 this data set is used to compute a minimum 1d velocity model for the region several tests are conducted to estimate model stability and hypocenter uncertainties leading to the conclusion that relative hypocenter location accuracy is about 500 m in latitude and longitude and 1 km in depth the minimum 1d velocity model serves as initial model in the non linear inversion for three dimensional p velocity crustal structure by iteratively solving the coupled hypocenter velocity problem in a least squares sense careful analysis of the resolution capability of our data set outlines the well resolved features for interpretation the resulting 3d velocity model shows generally higher average crustal velocities in the east and the well resolved area of the eastern gulf of arta exhibits a homogeneous velocity around 6 km s for the whole upper crust a pronounced north south trending zone of low velocities in the upper 5 10 km is observed in the area of the katouna fault zone kfz at greater depths below 10 km the kfz is underlain by high velocity material e w profiles suggest a horst graben structure associated with the kfz

geodetic determination of the kinematics of central greece with respect to europe implications for eastern mediterranean tectonics we use a new satellite laser ranging global positioning system slr gps solution at seven sites in anatolia and aegea to obtain a better definition of the extrusion motion of the anatolian aegean block with respect to europe we show that this motion can be described in a first approximation by a counterclockwise rotation which transfers most of the motion of arabia to anatolia we combine 78 displacement vectors obtained at common points of two triangulation nets measured in central greece in 1895 and 1975 with the slr gps measurements to compute the velocity field over greece with respect to europe these measurements indicate that central greece is a zone of extension between the anatolian aegean counterclockwise rotation to the south and the northern greece clockwise rotation to the north this extension is principally localized within the gulf of corinth to the east but is distributed to the west we then extrapolate this velocity field to the whole aegea and western anatolia using recently published gps results as well as the slr results the narrow dextral north anatolian fault which limits the velocity field to the north progressively gives way to a much wider boundary zone where extension becomes dominant we show that the collision between the mediterranean ridge and africa began 3 6 ma and we describe the modifications that this collision has produced on the kinematic pattern both in aegea and on the mediterranean ridge