on the hellenic subduction zone and the geodynamic evolution of crete since the late middle miocene abstract in recent syntheses of the geodynamic evolution of the aegean area the hellenic subduction zone and in particular its initiation plays a central role two basic aspects of the recent comprehensive model put forward by le pichon angelier and co workers are a initiation of subduction along the hellenic arc is inferred to have taken place approximately 13 ma ago whereas several others have suggested approximately 5 ma and b migration of the trench system to the south southwest giving rise to an extensional regime in the back arc region which led to general subsidence and formation of the present day aegean sea new data on the structure of the upper mantle underneath the aegean area indicate that the former aspect requires modification the seismic velocity structure indicating a northward dipping slab down to a depth of at least 600 km and the depth distribution of earthquake hypocenters can not be reconciled with straightforward initiation of subduction approximately 13 ma ago estimates of about 5 ma for the time of initiation of the present subduction zone are even more difficult to reconcile assuming 400 km as an upper bound for the effect of stretching of the aegean sea and of other processes contributing to the separation of crete from the eurasian mainland we arrive at an age for the hellenic subduction zone of at least 26 ma as to aspect b geological data of crete lend strong support to the idea that on crete compressional tectonics is of much greater importance than current models imply combining geophysical and geological data we propose a modification of the tectonic evolution for the cretan segment of the hellenic arc whereas the basic process of extension caused by a migrating trench system roll back in a land locked basin remains a very useful and sound concept the tectonics of the margins of a region subject to stretching in this case crete may be more complicated than hitherto thought in our model the documented fragmentation of crete into several basins which started about 12 ma ago is not attributed to initiation of subduction but to inception of the roll back process compressional tectonics on crete is taken to be associated with deformation of the crust resulting from the overall tensional stress regime

extensional tectonics of northwestern macedonia greece since the late miocene tectonic field studies in the florina ptolemais basin northwestern greece were carried out in an attempt to define the regional stress tensors in selected areas affected by neogene and quaternary faulting using recently proposed quantitative methods the analysis allows us to distinguish two extensional phases in the area a late miocene pliocene one with a ne sw average direction of extension and a pleistocene recent one with a nw se direction of extension we conclude that the principal stress axes 2 and 3 were interchanged in passing from one phase to the other these results are reasonably consistent with results of studies carried out in other parts of the aegean area especially the south aegean back arc domain

deformation of western greece during neogene clockwise rotation and collision with apulia following an early miocene phase of n s extension affecting the entire hellenides 50 clockwise rotation affected western greece modern gps analyses show rapid southwestward motion in southwestern greece over subducting oceanic lithosphere and no motion in the northwest where greece collided with apulia we aim to identify the deformation history of western greece associated with the rotation and the collision with apulia the timing of the various phases of deformation is constrained via detailed analysis of vertical motions based on paleobathymetry evolution of sedimentary sequences overlying the evolving structures the results show that accompanying the onset of rotation compression was re established in western greece in the early langhian around 15 ma subsequently western greece collided with the apulian platform leading in the late miocene to a right lateral strike slip system running from the aliakmon fault zone in northern greece via the kastaniotikos fault and the thesprotiko shear zone to the kefallonia fault zone offshore western greece ne sw compression and uplift of the ionian islands was accompanied by ne sw extension in southwestern greece associated with faster southwestward motion in the south than in the north this led in the middle pliocene around 3 5 ma to collision without further shortening in northwestern greece from then onward nw se to n s extension east of apulia and gradually increasing influence of e w extension in the south accommodated motion of the hellenides around the apulian platform as a result curved extensional basin systems evolved including the gulf of amvrakikos sperchios basin gulf of evia system and the gulf of corinth saronic gulf system

comment on episodic occurrence of strong mw6 2 earthquakes in thessalia area central greece by e e papadimitriou and v g karakostas earth planet sci lett 215 2003 395 409

palaeoseismological investigation of the tyrnavos fault thessaly central greece abstract a palaeoseismological investigation has been carried out along the tyrnavos fault an ese wnw trending north dipping normal fault representing one of the major tectonic structures bordering the late pleistocene holocene tyrnavos basin northern thessaly central greece according to geological structural morphotectonic and geophysical researches the tyrnavos fault has been geometrically and kinematically characterised as a typical aegean type active fault six trenches have been excavated and logged in detail in order to quantify the most important seismotectonic parameters like the characteristics of past earthquakes their ages the elapsed time from the last event the short term slip rate and the mean return period several samples have been also collected for absolute dating that has been performed with different techniques like tl osl and ams sedimentological structural and chronological data document a late pleistocene to holocene morphogenic activity of the tyrnavos fault which is characterised by vertical co seismic displacements of 20 40 cm and possible recurrence interval of 2 2 5 ka the comparison between the estimated short term ca 0 05 0 1 mm a and long term 0 1 0 2 mm a slip rates and the elapsed time from the last earthquake suggest the occurrence of a possible seismic gap along the tyrnavos fault due to the peculiar position of the selected site at the termination of the fault scarp in the bedrock the lateral variability in morphogenic behaviour of an active fault is also observed the location of the fault within a highly populated region and the proximity to the third largest town of greece larissa increases the seismic hazard of the area

long lived mesoscale eddies in the eastern mediterranean sea analysis of 20 years of aviso geostrophic velocities we analyzed 20 years of aviso data set to detect and characterize long lived eddies which stay coherent more than 6 months in the eastern mediterranean sea in order to process the coarse gridded 1 8 aviso geostrophic velocity fields we optimized a geometrical eddy detection algorithm our main contribution was to implement a new procedure based on the computation of the local and normalized angular momentum lnam to identify the positions of the eddy centers and to follow their lagrangian tra jectories we verify on two mesoscale anticyclones sampled during the egypt campaign in 2006 that our methodology provides a correct estimation of the eddy centers and their characteristic radius corresponding to the maximal tangential velocity our analysis reveals the dominance of anticyclones among the long lived eddies this cyclone anticyclone asymmetry appears to be much more pronounced in eastern mediter ranean sea than in the global ocean then we focus our study on the formation areas of long lived eddies we confirm that the generations of the ierapetra and the pelops anticyclones are recurrent and correlated to the etesian wind forcing we also provide some evidence that the smaller cyclonic eddies formed at the southwest of crete may also be induced by the same wind forcing on the other hand the generation of long lived eddies along the libyo egyptian coast are not correlated to the local wind stress curl but surprisingly their initial formation points follow the herodotus trough bathymetry moreover we identify a new formation area not discussed before along the curved shelf off benghazi

ground subsidence quaternary faults and vulnerability of utilities and transportation networks in thessaly greece ground fissures and subsidence have caused extensive damage in structures and the utility networks roads railroad line larisa nato airport telecommunication network in the plain of thessaly central greece in the last 20 years the fact that these fissures are parallel to quaternary faults controlling the structural evolution of the thessaly basin marked by intense recent seismic activity led some scientists to regard them as manifestation of tectonic creep even premonitory phenomena of major future seismic events a careful study of the geometric characteristics and of the kinematics of these ground fissures however revealed that they only reflect shear failure of the ground due to compaction of loose sediments following significant decline of the groundwater level due to over pumping i e a geotechnical and not a tectonic process furthermore theoretical considerations and modeling predict surface fissuring along zones of anomalous basement normal fault controlled topography this explains the correlation between ground fissures and active quaternary normal faults

constraints on the kinematics of post orogenic extension imposed by stretching lineations in the aegean region abstract new kinematic data from shear zones of tertiary age in the metamorphosed basement of the aegean region in combination with published kinematic lithological and palaeomagnetic data have enabled us to determine a detailed kinematic evolution of the region during post orogenic extension in the aegean three distinct stages are recognised firstly extension of both the western and eastern aegean started in the late oligocene early miocene 36 25 ma ago initially in an 023 direction stage two started shortly after this with the division of the aegean crust into the west aegean block a coupled assemblage of small blocks bound on its northwestern and southeastern margins by the scutari pec line and mid cycladic lineament fracture zones respectively between 25 ma and 3 ma the west aegean block underwent 30 clockwise rotation whilst the eastern aegean underwent on average 19 anticlockwise rotation rotation of the west aegean block as a semi coherent block was aided by the relative coolness of the block compared to the warmer eastern aegean region as the crust thinned and rotated the nw se trending faults which characterise the west aegean block were cross cut by e w trending faults in the latest miocene pliocene the thermal front migrated westwards into the west aegean block and the mid cycladic lineament ceased activity the final kinematic stage marked the start of the subdivision of the west aegean block into two portions in the pliocene the southeastern portion nw cycladic area coupled with the sw cycladic area to form a central aegean block that started to translate southwest the northern and western portion rotated a further 10 15 clockwise whilst the southeastern rim rotated anticlockwise these data demonstrate that aegean post orogenic extension is not dominated by a single block rotation or radial spreading event but is characterised by the sequential formation and reformation of lithospheric scale blocks that have developed in response to large scale partitioning of rotational strain

velocity and deformation fields in the north aegean domain greece and implications for fault kinematics derived from gps data 1993 2009 abstract gps rates based on data of an extended continuous and campaign type gps network in the north aegean domain are presented the data processed for the time period 1993 2009 is used to analyze the complex kinematic and deformation fields in the north aegean sea and adjacent regions the presence of slowly deforming areas is investigated southern bulgaria eastern macedonia and thrace move uniformly southward relative to eurasia 1 5 3 5 mm yr western macedonia epirus thessaly and central greece rotate rather coherently clockwise the region comprising the islands of limnos agios efstratios and alonnisos moves like a counterclockwise rotating slowly deforming block the new gps rates allow a quantification of the spatial change of strike slip motion and locking depth along the north aegean trough dextral strike slip motion diminishes from east toward west amounting to 21 2 mm yr along the saros basin and 12 5 mm yr south of the chalkidiki peninsula less than 5 mm yr 50 nstrain yr shear strain rate is transferred from the sporades islands pelion toward northern evia the locking depth is shallow for the ganos fault and the western saros basin 5 6 8 9 km it is deeper between the sporades islands and pelion 17 7 km corresponding to a more diffuse shear zone an elementary finite element model is applied to derive slip rates of the three main ene wsw to ne sw trending dextral strike slip faults in the north aegean large scale n s to nne ssw extension in the north aegean domain is analyzed by employing finite element and gps based strain rate analyses pronounced extension 100 nstrain is associated with known tectonic structures e g mygdonian graben northern gulf of evia in offshore areas such as the sporades basin the correspondence between gps derived extension rates and active fault structures is not entirely evident however important constraints are provided for seismotectonic interpretations

mapping the palaeo piniada valley central greece based on systematic microtremor analyses the application of seismic noise based techniques has become particularly popular in the last decades as they are not invasive and do not require large teams or expensive equipments the horizontal to vertical spectral ratio hvsr is commonly used not only in seismic microzoning studies as far as from noise recording constraining the fundamental resonant frequency but it is also possible to infer the depth of the bedrock knowing the average shear wave velocity of the overlying sedimentary cover or viceversa i e resonance equation for the purposes of the present research more than 300 single station noise measurements were carried out across the piniada valley central greece along and between several transects planned roughly perpendicular to the mean valley trend to understand the palaeogeographic and tectonic evolution of this area we needed an estimation of the geometry at depth of the bedrock underlying the fluvial deposits of the present day pinios river as a result for each measured site we calculated the depth of the bedrock and afterwards such values were opportunely interpolated for obtaining a 3d model of the palaeo piniada valley documenting for the first time the recent late quaternary inversion of the topographic gradient

a synthesis of the levantine basin circulation and hydrography 1985 1990 abstract the levantine basin circulation derived from recent data consists of a series of sub basin scale to mesoscale eddies interconnected by jets the basin scale circulation is masked by eddy variability that modulates and modifies it on seasonal and interannual time scales long term qualitative changes in the circulation are reflected in the bifurcation pattterns of ther mid basin jets relative strengths of eddies and the hydrographic properties at the core of these eddies confinement within the basin geometry strongly influences the co evolution of the circulation features surface measurements satellite images and the mass field indicate an entire range of scales of dynamical features in the region the complexity of the circulation is consistent with the basin wide and mesoscale heterogeneity of the hydrographic properties the interannual variability of liw levantine intermediate water formation in the region appears correlated with the changes in the circulation wintertime convective overturning of water masses reach intermediate depths and constitute a dominant mechanism of liw formation especially in anticyclonic eddies and along the coasts of the northern levantine basin

middle late holocene earthquake history of the gyrtoni fault central greece insight from optically stimulated luminescence osl dating and paleoseismology abstract the south dipping gyrtoni fault defines the northeastern boundary of the middle late quaternary tyrnavos basin central greece the recognition and recent tectonic activity of the fault were previously based on mapping remote sensing analyses and electrical resistivity tomography studies to understand the holocene seismotectonic behavior of the gyrtoni fault we excavated two paleoseismological trenches to estimate the timing of past earthquakes using luminescence dating we obtained twenty five fluvial colluvial sediment and pottery samples from both the upthrown and the downthrown fault blocks we applied the optically stimulated luminescence osl dating to coarse grain quartz using the single aliquot regenerative dose sar protocol our investigations of luminescence characteristics using various tests confirmed the suitability of the material for osl dating we found that the estimated osl ages were internally consistent and agreed well with the available stratigraphical data archaeological evidence and radiocarbon dates the performed paleoseismological analysis emphasized the occurrence of three surface faulting events in a time span between 1 42 0 06 ka and 5 59 0 13 ka also we recognized an earlier faulting event fourth has been also recognized to be older than 5 59 0 13 ka the mean throw per event value of 0 50 0 60 m could correspond to a ca mw 6 5 earthquake an average fault slip rate of 0 41 0 01 mm a and an average recurrence time of 1 39 0 14 ka were also estimated our results suggest that the elapsed time from the most recent event minimum age 1 42 0 06 ka is comparable with the mean return period

coherent synoptic disturbances in the australian monsoon abstractcoherent synoptic scale weather systems within the australian monsoon are identified and tracked in the isentropic potential vorticity pv field from the ecmwf interim reanalysis era interim dataset during the southern hemisphere summer the resulting dataset is then used to compile statistics and synoptic composites of australian monsoon disturbances on average a synoptic system is found in the region every 2 5 days however the time interval between consecutive events is highly variable meaning that the synoptic activity in the australian monsoon is not well represented by commonly employed spectral techniques the analysis reveals that most synoptic systems originate within the australian monsoon but at the 315 k level approximately 700 hpa a significant proportion of systems are first detected near the east coast of the continent where extratropical rossby waves are observed to frequently break the average australian monsoon weather system propagates from east to west at approximatel

tectonic stresses on the mainland of greece in situ measurements by overcoring abstract direct in situ measurements of the horizontal stresses in continental greece indicate a predominantly n s extensive stress considerable scatter of the azimuth of the axis of extension is found in thrace in contrast to a more homogeneous pattern in macedonia and peloponnesus these results are obtained with an overcoring technique in boreholes of a few meters they can be compared with neotectonic and seismic data to evaluate the present deformation process in this basin

adiabatic westward drift of indian monsoon depressions a large fraction of the rain received by continental india is produced by cyclonic vortices with outer radii of about 1000 km that are contained within the larger scale south asian monsoon flow the more intense occurrences of these vortices are called monsoon depressions these consist of bottom heavy columns of relative vorticity that propagate to the northwest in time mean low level eastward flow previous studies have argued that this apparent upstream propagation is caused by dynamical lifting west of the vortex centre with the resulting ascent producing vortex stretching that shifts the vortex to the west here analysis of over 100 indian monsoon depressions is used to show that low level vortex stretching has a spatial structure inconsistent with the observed propagation and is balanced by other terms in the low level vorticity budget instead monsoon depressions are shown to consist of potential vorticity maxima that have peak amplitude in the middle troposphere and propagate westward by nonlinear horizontal adiabatic advection i e beta drift the precipitating ascent in monsoon depressions makes a more minor contribution to the total storm motion and primarily acts to maintain the upright structure of the vortex these results suggest a new view of indian monsoon depressions as potential vorticity columns that propagate primarily by adiabatic dynamics

geometries of gilbert type deltas and large channels in the meteora conglomerate meso hellenic basin oligo miocene central greece the meteora conglomerate is a thick coarse grained unit of oligo miocene age in the meso hellenic basin consisting of gilbert type delta deposits wedge shaped bodies and deep channel fills gilbert type deltas prograded from the eastern margin basinward perpendicular to the nw se basin axis delta bodies are thicker in the distal portion where the dip of the foresets is lower than in the proximal area organized and disorganized conglomerates coexist suggesting a mixture of mass and turbulent flow processes the mass flow deposits seem to prevail in the uppermost part of the foresets channels up to 25 m deep are cut into the gilbert type delta deposits and have axes perpendicular to the progradational trend of the deltas giant bars displaying accretion of the downstream side formed inside the channels the channels were probably cut into gilbert delta deposits due to uplift of the source area or to a fall in sea level although large cross sets of both gilbert delta and channels have been formed by progradation they can be distinguished by i angle of foreset bed dips ii facies and textures and iii vertical sequences differences in these features aid in distinguishing gilbert type deltas from in channel bars

the earthquake of april 30 1954 in sophades central greece summary the sophades earthquake of 1954 april 30 marked the beginning of a series of earthquakes in central greece that culminated in the destructive events of 1955 and 1957 around the town of volos a thorough documentation of the surface expressions of the sophades earthquake was recently discovered in the diaries and photographic archives of yanni papastamatiou the surface manifestations included fractures and other ground disturbances this evidence is summarised in this report and is combined with geological and geophysical information available in the area the combined evidence suggests two possible fault zones that could be responsible for the earthquake both zones are consistent with a northerly extensional deformation similar to the one suggested for the region affected by the 1978 chalkidiki earthquakes in n greece

the development of tropical cyclones in the north west of australia case studies of developing and non developing tropical depressions in the north west australian region during the 1979 80 and 1980 81 cyclone seasons have been constructed using conventional and satellite observations these show that enhanced low level winds can occur during the lifetime of non developing disturbances and are not exclusively associated with cyclogenesis both types of system possessed lower level cyclonic circulations and there was an overlapping such that non developing storms could have stronger circulations than some developers at upper levels development was associated with the subtropical ridge being situated over the surface position of the disturbance in contrast the ridge tended to be located southwards of non developers these findings are supported by calculations of area averaged vorticity at 850 and 200 mb cross sections of zonal winds show that non developing systems could exhibit weaker vertical wind shears than some developing storms developers had only moderate shears at worst and maintained a well organized lower cyclonic circulation such features are consistent with both classes of disturbance existing within the monsoon shearline non development was caused by interactions with large scale flows in the southern hemisphere that prevented the necessary conditions for cyclogenesis from being all fulfilled this suggests a need for greater understanding of the influence of mid latitude events on depressions within the monsoon trough

a climatology of central american gyres abstractcentral american gyres cags are large closed cyclonic circulations that occur during the rainy season may november which can yield exceptional rainfall leading to catastrophic flooding and large societal impacts a reanalysis based climatology of cags is developed from an algorithm that distinguishes cag cases from other systems this algorithm identified cag cases based on circulation intensity a broad radius of maximum winds and the existence of closed earth relative cyclonic flow based on these criteria 47 cag cases were identified from 1980 to 2010 featuring a bimodal distribution of cases with maxima in may june and september november cag cases are composited into two categories based on their upper tropospheric pv structure nonbaroclinic cags are more common n 42 and characterized by an upper tropospheric anticyclone while baroclinic cags are less common n 5 and characterized by an upper tropospheric trough whereas a nonbaroclinic cag has anomalous moisture and preci

circulation and hydrography of the levantine basin results of poem coordinated experiments 1985 1986 abstract a brief review of the meteorological setting hydrography and the circulation in the levantine basin of the eastern mediterranean is given the recent high resolution data obtained in poem coordinated experiments of 1985 1986 are then used to optimally estimate the circulation in the basin in two different seasons and to describe the water mass distributions some of the features observed during the experiments support the historical knowledge on the locations of sub basin scale gyres and the general circulation in addition to which some new features are established details of the circulation such as the intensity the multiple scales and the three dimensional structure of the various vortices and the central levantine basin current are displayed extensively a variety of sub basin meso and sub mesoscale vortices occur with highly assymmetric baroclinic vertical structures some eddies split into multiple centres with depth interpreted as indicating possible coalescences a number of long lived eddies were persistent in both surveys the sub surface atlantic water aw is advected by and entrapped within the eddy field the levantine intermediate water liw at intermediate depths is shown to be maintained throughout the year in the northeastern sector of the levantine basin and along the periphery of the rhodes gyre the levantine intermediate water also has a patchy distribution owing to the advection and trapping by the eddy field which it helps to generate through adjustment processes

extensional compressional tectonics associated with the aegean arc comparison with the andean cordillera of south peru north bolivia extensional compressional tectonics are analysed along the convergent boundaries of the aegean arc and of the andean cordillera of south peru and north bolivia this paper deals only with deformations of miocene pliocene and pleistocene ages the prevailing regime in the aegean basin is extensional yet two compressional tectonic phases of u miocene l pliocene and of l pleistocene age have been recorded they are also known in many places all around the mediterranean thus forces that induce compressional tectonics in the aegean seem to have their origin outside the region they seem to be linked with changes in the conditions of convergence change in rate between the arabo african and eurasian plates beneath the andean cordillera of south peru north bolivia the subduction zone plunges at an angle of 25 30 as it does under the aegean arc there as in the aegean sea tectonics are predominantly extensional and several short lived compressional phases break up this extensional regime the latter may also be induced by changes of the conditions of convergence here between the nazca and south american plates beneath central peru north of the nazca ridge the subduction zone plunges at a small angle about 10 there neotectonic deformations are different in the recent they are essentially compressional or expressed by strike slip faulting geological data from the aegean and andes seem to demonstrate that the compressional deformation in the crust above subduction zones is strongly controlled by the stress conditions along convergent boundaries

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

global association of the madden julian oscillation with monsoon lows and depressions previous research has revealed that monsoon lows and depressions are modulated on intraseasonal time scales in a few regions including india australia and the east pacific this study examines whether such modulation occurs on a global scale and in particular how the madden julian oscillation mjo is associated with changes in synoptic scale vortices across all monsoon regions the spatial climatology of monsoon disturbances is largely insensitive to mjo amplitude however monsoon disturbance frequency mdf varies substantially with mjo phase with regional perturbations of 25 to 90 percent of the seasonal mean value across the tropics in off equatorial locations mdf maxima occur in locations where the mjo enhances low level cyclonic vorticity typically near the western edge of mid level moisture perturbations in contrast equatorial mdf perturbations are in phase with mjo moisture and rainfall anomalies with maxima in regions with strong low level zonal wind convergence

tectonic stresses on the boundary of the aegean domain in situ measurements by overcoring abstract direct in situ measurements of the horizontal stresses on the border of the aegean domain obtained by overcoring in boreholes a few meters deep revealed the various characteristics of plate boundaries continent continent collision subduction inter arc basin etc

aftershock relocation and frequency size distribution stress inversion and seismotectonic setting of the 7 august 2013 m 5 4 earthquake in kallidromon mountain central greece abstract on august 7 2013 a moderate earthquake noa ml 5 1 noa mw 5 4 occurred in central kallidromon mountain in the pthiotis region of central greece 2270 aftershocks were relocated using a modified 1 d velocity model for this area the b value of the aftershock sequence was b 0 85 for a completeness magnitude of mc 1 7 the rate of aftershock decay was determined at p 0 63 the spatial distribution of the aftershock sequence points towards the reactivation of a n70 10 e striking normal fault at crustal depths between 8 and 13 km a nnw sse cross section imaged the activation of a steep south dipping normal fault a stress inversion analysis of 12 focal mechanisms showed that the minimum horizontal stress is extensional at n173 e no primary surface ruptures were observed in the field however the earthquake caused severe damage in the villages of the kallidromon area the imaged fault strike and the orientation of the long axis of the aftershock sequence distribution are both at a high angle to the strike of known active faults in this area of central greece we interpret the kallidromon seismic sequence as release of extensional seismic strain on secondary steep faults inside the fokida viotia crustal block

paleoseismological investigation of the oblique normal ekkara ground rupture zone accompanying the m 6 7 7 0 earthquake on 30 april 1954 in thessaly greece archaeological and geochronological constraints on ground rupture recurrence 1 observations in trenches excavated across the ekkara rupture zone erz the longest of the sporadic ground ruptures that accompanied the m 6 7 7 0 earthquake of 30 april 1954 on the domokos fault zone dfz identify a left lateral oblique normal fault with a slip vector aligned with the regional extension direction verifying the tectonic origin of the erz the paleoseismological interpretation of stratigraphic soil stratigraphic and tectonic features is discussed with emphasis on the issues related to strongly oblique fault kinematics two pre 1954 events of ground rupture are recognized e1 and e2 and an event of ground cracking only e1a shortly after e1 event e2 was accompanied by larger displacement than e1 and 1954 but this does not necessarily imply a stronger earthquake archaeological dating of transported ceramic sherds constrains e1 between 6750 and 4450 b p more likely 6450 5750 b p luminescence dating of colluvial deposits and 14c dating of pedogenic carbonates stone coatings place e2 at 17 500 2500 b p preferred age in the hazard wise most conservative interpretation recent recurrence intervals of erz activations exceed 3195 years the sporadic nature of the 1954 ruptures precludes certainty on whether the erz has recorded every past activation of the dfz unless data are also collected from other dfz rupture zones minimum limiting estimates of 0 3 0 5 mm yr slip rate are derived for the erz and the true slip rate is not expected to exceed 1 mm yr slip rate estimates for the erz may be minima for the dfz slip rate however because coseismic deformation in the past may have been distributed to more than one rupture zones at the surface

the hellenic subduction zone a tomographic image and its geodynamic implications new tomographic images of the hellenic subduction zone demonstrate slab penetration in the aegean upper mantle to depths of at least 600 km beneath greece the lower part of the slab appears to be detached at a depth of about 200 km whereas it still seems to be unruptured beneath the southern aegean schematically we derive minimum time estimates for the duration of the hellenic subduction zone that range from 26 to 40 ma this is considerably longer than earlier estimates which vary between 5 and about 13 ma

the tectonic development of the hellenic arc and the sea of crete a synthesis abstract we use field analyses together with interpretation of aerial photographs orbital imagery and sea beam data to define more accurately the geometry of fault systems in the hellenic arc the tectonics of the area are dominated by extensional processes related to normal faulting we then use sea beam data previous oceanographic studies and extrapolation of field analyses on surrounding islands to describe the fault pattern of the cretan sea basin which is found consistent with the land fault pattern the mechanisms of the late neogene and quaternary deformation of the central and southern aegean region are analysed in terms of stress trajectories as revealed by field studies of fault populations we then examine the subsidence of the sea of crete in terms of a model of uniform stretching of the lithosphere the opening of the sea of crete was cylindrical and did not result in bending of crete this leads us to modify the southern portion of an earlier kinematic reconstruction of aegea in agreement with recent paleomagnetic results the implications of the opening of the sea of crete on the tectonic evolution of the straits to the west and east of crete are discussed finally the uplift of the outer arc is explained by underplating due to subduction

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

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

a diagnostic analysis of two intense monsoon depressions over australia abstract analyses of mean sea level pressure wind temperature and dewpoint am used to study the life cycles of two intense heavy rain producing monsoon depressions over northern australia two aspects are considered a the large forcing using both synoptic flow field changes and angular momentum budgets and b the role of convective and stratiform clouds using kinematic and thermodynamic budgets for each situation the northern hemisphere circulation becomes favorable well prior to genesis the short term trigger for development is the strengthening of the southern hemisphere subtropical ridge at the surface and an amplifying upper level trough and subtropical jetstreak to the southwest of the formation point the outer region structure of these monsoon depressions is remarkably similar to that of a tropical cyclone even though the systems develop over land during development maximum convective heating occurs at middle levels and within a region of already high cyclonic vorticity evidence sug

40ar 39ar laserprobe direct dating of discrete deformational events a continuous record of early alpine tectonics in the pelagonian zone nw aegean area greece abstract the pelagonian zone of the hellenides which occurs in the northwestern aegean region of the eastern mediterranean contains remnants of a high pressure metamorphic belt which subsequently underwent localized reworking during low temperature deformational events formation of alpine deformational structures in the ossa massif northern pelagonian zone occurred at metamorphic temperatures which failed to reset most pre alpine 40ar 39ar cooling ages in muscovite porphyroclasts the low metamorphic temperatures at alpine times have preserved the argon isotopic signature in white mica bearing deformational structures which allows direct dating of these structures and refinement of the alpine tectonic history in the region after separation of carefully selected and characterized mica generations application of sensitive 40ar 39ar laserprobe dating has resulted in a continuous record of the early alpine tectonic history of the ossa massif from the early cretaceous well into the eocene the early alpine history of the ossa massif records cooling of basement thrust slices which are mostly hercynian granites and metamorphics below ca 350 c by 100 ma while lower tectonostratigraphic levels of the basement had already cooled below these temperatures at around ca 285 ma blueschist facies mylonite fabrics related to a top to ene direction of tectonic transport yield ages as old as 84 5 3 3 ma exhumation of the blueschist facies sequences was initiated at ca 54 ma and involved tectonic activity along blueschist facies and greenschist facies mylonites zones final wsw ward transport of the metamorphic sequence across the structurally lowest and supposed autochthonous series occurred at around 45 ma and resulted in termination of the ductile deformation history in the studied area this study confines the onset of high pressure metamorphism in the pelagonian zone to an interval between 100 ma and 85 ma and has shown that high pressure metamorphism had terminated by ca 54 ma the recognition of an early to middle alpine cycle lasting over 30 million years and involving crustal shortening high pressure metamorphism exhumation and subsequent crustal shortening is a key contribution to a better understanding of the early alpine tectonic history of the aegean region and eastern mediterranean

fault parameters of the 1980 mw 6 5 volos central greece earthquake from inversion of repeated leveling data the 1980 volos almyros seismic sequence the last of an unusual clustering of earthquakes with surface magnitude 6 0 7 0 which hit thessaly central greece between 1930 and 1980 is among the least studied recent earthquakes in greece repeated measurement of three first order spirit leveling traverses crossing the meizoseismal area of the seismic sequence indicates that between 1970 1971 and 1988 1989 a subsidence of about 35 cm is observed at the almyros neogene quaternary graben the observed displacements are significant against random and systematic errors and can be assigned to the 1980 earthquake sequence inversion of leveling data using an elastic dislocation model constrained by structural and seis mological data indicates that the mainshock mw 6 5 and the largest aftershock mw 6 1 were probably associated with reactivation of two subparallel homothetic nor mal faults marking the northern margin of the almyros neogene quaternary graben

why joints are more abundant than faults a conceptual model to estimate their ratio in layered carbonate rocks it is a commonplace field observation that extension fractures are more abundant than shear fractures the questions of how much more abundant and why are posed in this paper and qualitative estimates of their ratio within a rock volume are made on the basis of field observations and mechanical considerations a conceptual model is also proposed to explain the common range of ratios between extension and shear fractures here called the j f ratio the model considers three major genetic stress components originated from overburden pore fluid pressure and tectonics and assumes that some of the remote genetic stress components vary with time i e stress rates are included other important assumptions of the numerical model are that i the strength of the sub volumes is randomly attributed following a weibull probabilistic distribution ii all fractures heal after a given time thus simulating the cementation process and therefore iii both extensional jointing and shear fracturing could be recurrent events within the same sub volume as a direct consequence of these assumptions the stress tensor at any point varies continuously in time and these variations are caused by both remote stresses and local stress drops associated with in situ and neighbouring fracturing events the conceptual model is implemented in a computer program to simulate layered carbonate rock bodies undergoing brittle deformation the numerical results are obtained by varying the principal parameters like depth viz confining pressure tensile strength pore fluid pressure and shape of the weibull distribution function in a wide range of values therefore simulating a broad spectrum of possible mechanical and lithological conditions the quantitative estimates of the j f ratio confirm the general predominance of extensional failure events during brittle deformation in shallow crustal rocks and provide useful insights for better understanding the role played by the different parameters for example as a general trend it is observed that the j f ratio is inversely proportional to depth viz confining pressure and directly proportional to pore fluid pressure while the stronger is the rock the wider is the range of depths showing a finite value of the j f ratio and in general the deeper are the conditions where extension fractures can form moreover the wider is the strength variability of rocks i e the lower is the m parameter of the weibull probabilistic distribution function the wider is the depth range where both fractures can form providing a finite value of the j f ratio natural case studies from different geological and tectonic settings are also used to test the conceptual model and the numerical results showing a good agreement between measured and predicted j f ratios

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

small synoptic mesoscale eddies and energetic variability of the eastern levantine basin mesoscale eddies are energetically dominant over most of the world s ocean1 the local dynamics of eddies is now a central problem of physical oceanography2 and their statistics control aspects of the general circulation3 the horizontal scale of eddies is generally related to but somewhat larger than the rossby internal deformation radius the depth scale multiplied by the buoyancy frequency divided by the coriolis frequency in the eastern mediterranean which is not well explored or understood the internal radius is known to be 12 km or 4 times smaller than in the north atlantic the study of such eddies requires very fine sampling which hinders their accidental discovery by using a dedicated data set and objective analysis methods we have estab ished the existence of small synoptic mesoscale eddies and jets which constitute a variable and turbulent current regime and dominate the general circulation flow of the levantine basin their existence in the mediterranean has an impact on all aspects of basic and applied marine science there both conceptually and with respect to experimental and monitoring programme designs

active normal fault evolution in greece revealed by geomorphology and drainage patterns active normal fault systems in greece are associated with characteristic geomorphology and drainage patterns that are recognizable in satellite images and digital topography some allowance must be made for the nature of the footwall rocks which can exert an important influence on these patterns and we examine the three main types in greece hard mesozoic limestone relatively soft schist volcanic rocks or flysch and very soft neogene sediments drainage and geomorphology can be used to identify active faults that were previously unknown but can also reveal information about plio quaternary fault evolution and interaction that may be inaccessible by other means we illustrate such processes with examples showing the migration of normal fault systems into their hanging walls and the change in normal faulting activity from nw se faults to e w faults both of which are common in greece

regional and local stress field orientation inferred from quantitative analyses of extension joints case study from southern italy 1 an intense tectonic activity in eastern sicily and southern calabria italy is well documented by the differential uplift of late quaternary coastlines and by the record of the strong historical earthquakes the extensional belt that crosses this area is dominated by a well established wnw ese oriented stretching direction however this area is largely lacking of any structural analysis for defining the tectonics at a more local scale the analysis of systematic extension joint sets affecting pleistocene deposits presented in this paper allows to infer the causative tectonic stress tensor by means of a quantitative inversion technique local perturbations of the first order regional stress field are consequently recognized such perturbations are interpreted as due to interferences between large active faults and their particular geometrical setting these results contribute to the understanding of the quaternary tectonic evolution and the present day stress regime

the pelagonian zone in greece a polyphase deformed fragment of the cimmerian continent and its role in the geotectonic evolution of the eastern mediterranean data from macedonia greece correlated with those reported from the pontides turkey indicate that the pelagonian zone of the hellenides represents a fragment of the cimmerian continent which separated the paleo tethys and neo tethys oceans a permo triassic age is suggested for separation of the paleozoic continent and initial rifting in the two oceanic basins as the pelagonian zone represented the northwestern european end of the cimmerian continent the paleo tethys and the northern branch of neo tethys would have been very close to each other on either side of this zone thus both oceans at their european end closed within a short time of each other in the late jurassic early cretaceous the sequential development of the two oceans outlines a model for the geotectonic evolution of the internal hellenides in which a correlation of thrusting and folding phases is also given

stress variability and brittle tectonic structures the problem of stress variability both in space and time during brittle deformation of rocks is faced in this note several possible causes of the temporal and spatial variations of the stress tensor are reviewed and discussed a genetic partitioning of the stress tensor is proposed showing that any stress field within a crustal volume can be seen as the sum of relatively simple stress tensors associated to specific genetic components the genetic components discussed in this note are the gravitational the tectonic the fluid the thermal and the diagenetic one each genetic component is a function of several parameters but for all of them the possible important role played by the variable time is emphasised according to numerous researches based on theoretical and experimental grounds brittle deformation in a rock mass occurs when some critical conditions are reached starting from initial equilibrium conditions and leading to even different stress conditions as a consequence of failure field examples are presented and data from literature are discussed to exhibit evidences from complex tectonic structures and to argue about small and large scale spatial variations as well as about short and long term temporal variations of the stress trajectories and of the stress magnitudes that continuously occur during a brittle deformational event the relationships between local and temporal stress variations and what is commonly defined the regional stress field are discussed adding recommendations for future researches

revision of the timing magnitude and distribution of neogene rotations in the western aegean region to evaluate the dimension and the timing of the clockwise rotating domain and the nature of the structures that accommodate the rotating domain in the western aegean region paleomagnetic analyses were carried out in northern western and southwestern greece the results show that the rotating domain covers an area including the external albanides western mainland greece including evia and probably at least partly the peloponnesos smaller clockwise rotations on the order of 30 408 were reported previously from the chalkidiki peninsula and the islands of skyros and limnos previously two phases of approximately 258 of rotation were suggested the last one during the plio pleistocene our analysis shows that the western aegean domain rotated approximately 408 clockwise between 15 13 and 8 ma followed by an additional 108 after 4 ma the rotating domain is accommodated in the north by deformation associated with the scutari pec fault zone and in the west by the ionian thrust and the hellenic subduction zone to the south no rocks older than 10 ma are available so no conclusive data are obtained to the east of the rotating domain extensional detachment systems of the cyclades and rhodope areas were active during the rotation phase and may explain at least part of the differences in finite amounts of rotation between nonrotation or counterclockwise rotations observed in northern and eastern greece and the large clockwise rotations in western greece d 2004 elsevier b v all rights reserved

an integrated study to recent tectonics in central japan seismological geodetic morphotectonic and structural data compared abstract the abundance of seismological geodetic morphotectonic and structural data for central japan allows an integrated approach to the study of recent tectonics this study has been conducted in a region where an apparent uniformity of geodynamic conditions existed during quaternary times four independent data sets have been collected minor and major earthquakes mesoscale faults and large scale morphological dislocations all of them have been reduced to a common format including fault plane orientation direction and sense of movement the analysis has been carried out by applying different methodologies commonly employed in structural geology in order to obtain both qualitative and quantitative estimates of the stress field where the latter kind of analyses also provides the principal stress directions and the ratio r 1 2 1 3 the results of each data set are internally consistent but above all the similarity between the three principal stress directions of the four data sets is straightforward showing a clear strike slip regime with an ese wnw trending 1 and a nne ssw trending 3 whose averages are 288 05 and 198 10 respectively numerous geodetic data from the region show exactly the same direction of maximum contraction and broadly confirm previous large scale stress trajectories maps by considering characteristic depth age and fault dimension for each fault set it is possible to understand better the recent late quaternary present tectonic evolution of the area where a progressive nne ssw restraining appears to occur due to the possible westward migration of the compressional zone associated with the itoigawa shizuoka tectonic line or the southern increasing constrain produced by the philippine sea plate this geodynamic process will eventually produce a permanent swap of the 2 and 3 axes

a study of the 1980 summer seismic sequence in the magnesia region of central greece summary properties of the seismic sequence foreshocks and aftershocks of the 1980 july 9 m 6 5 earthquake in the magnesia region of central greece are investigated fault plane solutions of the three major shocks of the sequence distribution of epicentres geological data and field observations show that the seismic fault is a normal trending ene wsw and dipping sse evidence that its dip angle decreases with depth is presented the parameter b in the frequency magnitude relation was found equal to 0 84 for the foreshocks and equal to 1 28 for the aftershocks while the decay parameter p of the time distribution of the aftershock frequency was found equal to 0 72 the frequency of foreshocks which started on july 4 increased till july 6 but after that decreased till the occurrence of the main shock while their average magnitude decreased continuously between july 4 and 9 a striking similarity between the focal properties of shocks of this sequence and of shocks of two other sequences which occurred in 1978 and 1981 in the back arc aegean area is attributed to tensional forces acting in this area since the middle pleistocene

tectonic geomorphology of the easternmost extension of the gulf of corinth beotia central greece the easternmost sector of the gulf of corinth the beotia area in central greece is an area with active normal faults located between the two major rift structures of central greece the gulf of corinth and the north gulf of evia these active normal faults include wnw to e w and ne to ene trending faults affect the landscape and generate basin and range topography within the beotia we study four normal fault zones and drainage basin geometry in the easternmost sector of the gulf of corinth to document the impact of active tectonics on the landscape evolution fault and drainage geometry are investigated based on detailed field mapping and high resolution digital elevation models tectonic geomorphic analysis using several parameters of active tectonics provides information concerning the relative tectonic activity and fault growth in order to detect areas of lateral stream migration that could indicate recent tectonic activity the transverse topographic symmetry factor and the asymmetry factor are used to analyse drainage basin geometry in six large drainage basins and a drainage domain covering the study area our results show that vertical motions and tilting associated with normal faulting influence the drainage geometry and its development values of stream gradient indices sl are relatively high close to the fault traces of the studied fault zones suggesting high activity mountain front sinuosity smf mean values along the fault zones ranges from 1 08 to 1 26 valley floor width to valley height ratios vf mean values along the studied fault zones range between 0 5 and 1 6 drainage basin shape bs mean values along the fault zones range from 1 08 to 3 54 all these geomorphic parameters and geomorphological data suggest that the analyzed normal faults are highly active lateral fault growth was likely produced by primarily eastward propagation with the wnw to e w trending faults being the relatively more active structures

occurrence patterns of strong earthquakes in thessalia area greece determined by the stress evolutionary model caputo 1 criticizes our work 2 and considers itsresults as dat least doubtfult his criticism concerns the tectonic setting we described the seismologicaldata base we used the long term slip rate we haveadopted and the stress evolution and triggering ofstrong earthquakes we derived by the application ofseismological methods of these four subjects thefirst one is mostly related with his published work for this reason we discuss here in some detail severalproblems concerning active faults we show that reli able location and estimation of parameters of suchfaults requires a combined use of geological andseismological data as we have done in our work 2 we make also a brief comment on each of theother three subjects and show that his relative argu ments have also no scientific base 1 seismic faultscaputo 1 finds important differences between thefault system we used 2 and the fault system pro posed by caputo and pavlides 3 and shows it in twofigures figs 1 and 2 in 1 he attributes thesedifferences to our bmisunderstanding or misuse ofthe literature dataq it is true that there are significantdifferences between the two fault maps but the reasonhe attributes it is untrue this difference is due to thefact that their fault map is based almost exclusively ona specific sample of geological observations 3 whileour fault map is based on a wealth of reliable macro seismic and instrumental seismological observations as well as on all available geological information 2 4 the faults for which parameters we used in ournumeric modeling are the specific seven ones kera midi larissa sofades pagasae farsala agrafa aghialos described in our work 2 table 3 ineach of these faults one or more destructive earth quakes have occurred during the instrumental period since 1905 these parameters location orientation size kind of faulting have been all reliably estimatedon the basis of well defined isoseismals 25 340observations were used for each of these isoseismal

deformation partitioning in a transtension dominated tectonic environment the illustrative kinematic patterns of the neogene quaternary ptolemais basin northern greece the structure of the neogene quaternary ptolemais sedimentary basin exemplifies the importance of deformation partitioning in the kinematic history of basin formation structural analyses were carried out at outcrop from the metre to kilometre scale on basin marginal faults and on structures reflecting deformation of the interior of the basin deformation is partitioned into three spatially separated but kinematically linked domains two transtensional dominated domains in the northern and in the southern parts are separated by a transpressional dominated domain in the central part of the basin intense synsedimentary deformation of pliocene quaternary deposits occurred in all three domains dominant structures that affected pre neogene lithologies and the basin fill include e ne w sw and nw se trending basin kilometre scale marginal faults we propose that the structures of the three domains were active simultaneously during progressive deformation reflecting an overall transtensional dominated regime the deformation is imposed by boundary conditions and is consistent with the pliocene quaternary large scale deformation in northern greece that includes clockwise dextral rotations of crustal blocks and gravity driven nnw sse extension strong partitioning of deformation produced contrasting structures which do not reflect a sequence of events related to a regional stress fields that changed with time

a global climatology of monsoon low pressure systems the first global climatology of monsoon low pressure systems is presented here based on the era interim reanalysis low pressure systems are classified into three intensity categories and particular focus is given to systems in the category corresponding to a traditional definition of monsoon depressions vortex tracks are identified using an automated algorithm applied to the distributions of 850 hpa relative vorticity sea level pressure and surface wind speed for 1979 2012 roughly two to three times as many monsoon low pressure systems form in the northern hemisphere as in the southern hemisphere during local summer the frequency of genesis typically peaks in local summer but low pressure systems form throughout the year in every monsoon region interannual variability is weak with standard deviations of summer counts typically being below 10 of the long term summer mean regional composites reveal that monsoon depressions in india the western pacific and northern australia share a common structure consisting of a warm over cold core and a top heavy column of potential vorticity that extends from the surface to the upper troposphere a separate class of monsoon low pressure systems develops over dry regions of west africa and western australia with a shallow composite structure having a warm core in the lower troposphere and cyclonic potential vorticity confined to a thin near surface layer low pressure systems in nearly all monsoon regions are estimated to account for a large fraction from about 40 to more than 80 of summer precipitation on the poleward edge of the climatological mean precipitation maxima

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

sedimentary basins formed and carried piggyback on active thrust sheets small sedimentary basins that formed on the apennine southern margin of the po basin complex northern italy have been studied using borehole and seismic reflection information and their evolution can be dated using the largely marine biostratigraphy of the miocene to quaternary sediments these studies show that the basins formed and were filled while being carried on moving thrust sheets and they are therefore named piggyback basins each of these basins corresponds to the active phase of a different thrust front ramp on the pyrenean northern margin of the ebro basin complex northern spain similar piggyback basins formed between eocene and mid miocene time they have since been uplifted and eroded and may therefore be studied in outcrop in northern spain much of the basin fill sediment was deposited in nonmarine environments

variability of the cyprus warm core eddy during the cyclops project the circulation of the southeastern levantine basin eastern mediterranean as determined from several oceanographic cruises carried out in april may and august 2001 and in march may and august 2002 was investigated within the framework of the cyclops experiment the may cruises were part of cyclops while the others which provide supporting data were part of the ongoing cybo project the may 2002 data provided the location of the eddy and physical description of the circulation which were crucial for the in situ phosphate sf6 addition experiment of cyclops the major flow features observed in the region south of cyprus displayed strong variability within the period of the observations throughout the entire study period the warm core anticyclonic eddy known as the cyprus eddy was a dominant component of the circulation during the 18 months covered by the cruises the eddy drifted slowly to the southwest at the end of the cyclops cruises the center of this persistent recurrent eddy was found approximately 100 150 km west of its previously observed location since the 1980s the mid mediterranean jet mmj associated with the rim of this eddy followed a complex path south of cyprus depending upon the eddy s shape and location during most of the study period the mmj surface currents near the northern periphery of the rim of the eddy were as high as 35 45 cm s in may 2002 during the in situ experiment the near surface seasonal thermocline inhibited downward mixing of the added tracers while the strong horizontal current around the rim of the clearly defined eddy core limited the lateral spreading and dilution of the patch finally the westward shift of the cyprus eddy allowed space for the generation of a secondary anticyclonic eddy in the eastern part of the domain the co existence of the two anticyclonic eddies during 2002 along with the development of a third anticyclonic eddy closer to the coast of egypt provides strong evidence for the re establishment of the previously observed multi pole sub basin scale shikmona gyre r 2005 elsevier ltd all rights reserved

episodic occurrence of strong mw 6 2 earthquakes in thessalia area central greece abstract between 1954 and 1957 three seismic sequences struck the southern margin of thessalia basin central greece the proximity in time 3 yr and space 100 km between these three seismic manifestations suggests a possible link between them their interconnection is then investigated by resolving changes of coulomb failure function cff during the 20th century coulomb stress changes were calculated assuming that earthquakes can be modelled as static dislocations in an elastic half space and taking into account both the coseismic slip in strong m w 6 2 earthquakes and the slow tectonic stress buildup associated with major fault segments the study area constitutes one of the most active fault zones of the greek mainland where several strong events have occurred in the past as it is inferred from both historical and instrumental information however no earthquake with m w 6 2 occurred there for about two centuries before the last activity this fact led us to investigate the occurrence mode of strong events in the thessalia area since the 16th century when adequately reliable historical information exists for the stronger events forasmuch as they occur in clusters both in space and time as it is the case during the 20th century the episodic occurrence of strong events in this area is substantiated when these episodes are separated by longer quiescent periods since during the 20th century all the earthquakes have occurred in stress enhanced areas by extending the stress calculations to 2025 and provided that no additional large m w 6 2 earthquake occurs between 2002 and 2025 assessment for the future seismic hazard is given

structure and evolution of warm core eddies in the eastern mediterranean levantine basin two recent cruises of the r v shikmona provided detailed coverage of a large portion of the levantine basin of the eastern mediterranean the first cruise was conducted in october 1985 corresponding to late summer and the second was in march 1986 corresponding to the following winter an objective analysis of the combined conductivity temperature depth and expendable bathythermograph data from these cruises reveals a variety of warm core and cold core mesoscale eddies during both seasons some of these features are unique to each cruise while others appear to retain their identities from summer to winter of the latter there are two intense anticyclonic eddies one of these appears to have formed off the coast of egypt as a meander of the north african current the other is a rather persistent quasi stationary feature to the southeast of cyprus which has been seen near this location for over 3 years lack of adequate satellite images for the period and region covered led us to use water mass properties to identify and track the development of these two eddies below the layer of seasonal influence it was found that each eddy had a unique signature in its ts diagram which changed very little over the 6 months covered by the two cruises and the period between them the water mass properties also provide additional evidence as to the possible formation regions for these two eddies

circulation in the eastern levantine basin determined by inverse methods abstract a finite difference linear inverse model is applied to hydrographic data from six summer and fall cruises in a small area 250 200 km of the eastern mediterranean sea the temperature and salinity equations are used to form a linear set of equations for the reference geostrophic velocities and the mixing coefficients which are then solved by singular value decomposition advection by the horizontal velocities is the dominant process affecting the temperature and salinity fields in the region and the model successfully resolves the horizontal velocities mixing and vertical advection are smaller by an order of magnitude and the model cannot fully resolve the mixing coefficients and vertical velocities the six velocity fields calculated from the data indicate a very strong variability that makes it difficult to identify a repeating summer or fall circulation patterns on the scale of the region covered by the data an appendix contains the details of a new procedure for including linear inequ

map view restoration of aegean west anatolian accretion and extension since the eocene 1 the aegean region greece western turkey is one of the best studied continental extensional provinces here we provide the first detailed kinematic restoration of the aegean region since 35 ma the region consists of stacked upper crustal slices nappes that reflect a complex paleogeography these were decoupled from the subducting african adriatic lithospheric slab especially since 25 ma extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes we reconstruct up to 400 km of trench perpendicular ne sw extension in two stages from 25 to 15 ma the aegean forearc rotated clockwise relative to the moesian platform around euler poles in northern greece accommodated by extensional detachments in the north and an inferred transfer fault se of the menderes massif the majority of extension occurred after 15 ma up to 290 km by opposite rotations of the western and eastern parts of the region simultaneously the aegean region underwent up to 650 km of post 25 ma trench parallel extension leading to dramatic crustal thinning on crete we restore a detachment configuration with the mid cycladic lineament representing a detachment that accommodated trench parallel extension in the central aegean region finally we demonstrate that the sakarya zone and cretaceous ophiolites of turkey cannot be traced far into the aegean region and are likely bounded by a pre 35 ma n s fault zone this fault became reactivated since 25 ma as an extensional detachment located west of lesbos island the paleogeographic units south of the izmir ankara sava suture however can be correlated from greece to turkey

the north aegean region a tectonic paradox in the past two decades several publications have been presented concerning the recent and active fault geometry kinematics and geodynamics of the aegean region and particularly of the northern sector data and results are often contradictory and because of the complexity of the area most hypotheses and models should be considered carefully the right lateral movement of the north anatolia fault continues into some branches of the north aegean fault system there strike slip motion along ne sw trending faults coexists with dip slip e w trending faults in the frame of an extensional regime related to n s crustal stretching if we take into account the geodynamic environment of the region several mechanical problems arise to the east the aegean is compressed by the westward convergence of anatolia while to the south and west along the hellenic arc a hemiradial compression occurs due to subduction although the north anatolia north aegean trough fault system resembles a restraining bend the whole area is in fact affected by pure extension and local transtension along ne sw trending structures accordingly the major paradox of the area and especially in the western sector fault termination is the occurrence of extension where compression should regionally or at least locally predominate

neogene quaternary tectonic stratigraphy of the eastern southern alps ne italy abstract in order to reconstruct the neogene quaternary tectonic stratigraphy of the eastern southern alps the late tortonian lower pleistocene foredeep clastic sequences cropping out in the veneto and friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers pitted pebbles the eastern southern alps is the result of a typical polyphase tectonic activity initiated in late oligocene characterised by the occurrence of several non coaxial stress regimes based on careful analyses of the pebbles surfaces shape and orientation of the indented features and following a systematic and statistical approach the mean orientation of the maximum compressive stress axis 1 has been obtained for more than 30 sites of measurements along the ca 120 km long investigated piedmont area the affected lithostratigraphic units and the orientation pre versus post tilting of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean 1 direction and timing late tortonian 1 313 00 late messinian early pliocene 338 04 late pliocene 314 03 and early middle pleistocene 160 03 the tectonic stratigraphy of the eastern southern alps during the last ca 10 ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the 1 axis between an nnw sse and nw se directions twist tectonics taking also into account literature data about older deformational events chattian burdigalian and serravallian tortonian we analyse the neogene quaternary tectonic evolution in the frame of the central mediterranean realm and compare it with the convergence direction between the adria africa and europe lithospheric plates we show that compressional directions within the eastern southern alps are basically governed by the remote plate convergence though since late messinian the approaching northern apennines started to play a crucial role within the investigated area alternating short lived phases 1 2 ma of coupling and decoupling along the basal detachment of the apennines accretionary wedge probably caused temporary perturbations of the local stress field and complex accommodation structures in this region of ongoing crustal collision

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

late cainozoic geodynamic evolution of thessaly and surroundings central northern greece abstract in the framework of the late alpide deformation of greece and of the recent and active extensional tectonism of the aegean region the geotectonic evolution of the thessaly region central northern greece has been examined using a quantitative and qualitative structural analysis stratigraphie sedimentological morphotectonic and seismological data the geometry of the faults their architecture and the knowledge of the stress pattern are used to explain some aspects of the tectonics and crustal dynamics of thessaly and the surrounding area the oldest compressional phases taken into account show a mean ene wsw trending direction of shortening and have been defined as late alpide early aquitanian and langhian a later late miocene pliocene ne sw oriented extensional phase has been related to the hellenic post orogenic collapse which developed behind the collisional front between the aegean eurasia and african plates this phenomenon diachronically migrated from the east central macedonia thermaikos basin towards the west epirus albania where it is still active as a consequence of this second phase the area forms a basin and range like structure the third and last phase middle pleistocene present is characterized by a n s direction of extension and affects the entire aegean region it generated new e w trending basins superimposed on the inherited ones this gave as a final result the complex block pattern we can see today the recent and active right lateral strike slip movements along the north aegean trough seem to stop in the sporades basin and do not affect the uppermost crust of mainland greece a further wnw ese directed extension observed occasionally in central and northern greece could be explained by local events or as block related deformation

late neogene to quaternary contractional structures in crete greece abstract based on geological and tectonic investigations carried out along an n s coast to coast transect across central crete southern aegean greece new meso and macro structural data mainly collected from neogene quaternary deposits are presented and discussed the occurrence of large scale folds and thrusts together with diffuse minor contractional structures as well as the overall geometry of the fault bounded sedimentary basins document the persistence of a tortonian early pleistocene contractional regime characterized by an nnw sse to nne ssw shortening direction and affecting the upper crust this contractional event s was associated with the ongoing hellenic subduction and caused the development of a southwards migrating out of sequence thrust system consisting of both reactivated inherited structures and new ones the new data emphasize the importance and the extent of this contractional event intervening between the early middle miocene exhumation phase and the still active upper crustal extensional regime that was resumed in the island only during pleistocene when the region was affected by diffuse normal faulting while the contractional event was likely due to a stronger coupling along the overall subduction system the onset of the new extensional stress conditions was probably related to a sudden southwards jump of the basal detachment along the lithospheric african subduction that caused a general stress release in the uppermost crust

on the ocean circulation off the egyptian coast determined from steric height distributions on the basis of the hydrostatic equation the total steric departures from mean sea level for a water column of 1000 m depth were calculated for the mediterranean water off the egyptian coast during winter and summer seasons from the total steric height distribution over the investigated area the geostrophic currents were determined the results of this study reveal that the steric departures show a seasonal trend being low in winter and high in summer this is in phase with the eastern mediterranean sea level changes the currents off the egyptian coast are considered an extension of the north african current flowing to the east the general circulation pattern was characterized by appearance of an anticyclonic gyre off mersa matruh in the central region around longitude 28 e during both seasons

structural analysis of recent and active faults and regional state of stress in the epicentral area of the 1978 thessaloniki earthquakes northern greece during spring and summer 1978 macedonia greece suffered damaging seismic activity during the two main shocks which occurred on may 23 mb 5 7 and june 20 mb 6 1 seismic open cracks and faults were formed in the epicentral area 25 km nne from thessaloniki they have been mapped and their kinematics analyzed these studies have shown that they result from the reactivation of existing faults of pleistocene recent and historical age and that the crust is stretching along a n s to nne ssw direction in that part of the north aegean principal stress directions have been computed from the slip vectors measured on recent neotectonic faults and seismic cracks and faults this computation utilizing a simple mechanical model homogeneous deformation through the addition of small and independent displacements of rigid blocks in a highly fractured body a striking feature of this analysis is that the tensional directions 3 deduced from seismic faulting and from recent neotectonic faulting are nearly the same they are compatible with the regional tension axis deduced from focal mechanisms of north aegean and with the focal mechanisms of the 1978 thessaloniki main shocks they are also compatible with in situ stress measurements in this region studies of superficial seismic faulting strongly support previous assumptions proposed from aftershock distribution the 1978 thessaloniki earthquakes resulted from reactivation of several different faults situated within the same ne dipping fault zone of upper eocene lower oligocene age and older separating the serbo macedonian massif from the peonias east vardar zone

long term evolution and dynamics of a persistent warm core eddy in the eastern mediterranean sea abstract shipboard data from seven cruises covering april 1988 october 1990 are analyzed to follow the dynamical evolution of a persistent warm core eddy located to the southeast of cyprus the eddt is characterized by an isothermal isohaline lens of water wedged between the seasonal and permanent thermoclines in the winter this thermostad extends from the surface to a depth of nearly 400 m while in other seasons it lies in the layer from 200 to 400 m the data indicate that the temperature and salinity of the core of the eddy remained constant throughout most of 1989 and then increased abruptly with a slight increase in in the winter of 1989 1990 the velocity jet usually appears between the surface and 200 m at a mean distance of 35 km from the center of the eddy speeds in the jets typically exceed 25 cm s 1 and occasionally reach 50 cm s 1 during 1989 the eddy spins down as indicated by a loss of kinetic energy this weakening permits an abrupt renewal or exchange of core water during the winter of 1989 1990 the remnants of the previous core are apparently forced to sink into the permanent thermocline where the water may be free to spread laterally if the cross isopycnal gradient of potential vorticity is weak this process could explain the cycle of levantine intermediate water formation in the centers of warm core eddies and its eventual lateral spreading finally the eddy slowly begins to spin up again in 1990

seismotectonics of the aegean region abstract fault plane solutions neotectonic field observations and in situ stress measurements have been used to determine the stress field associated with the active deformation of the lithosphere in the aegean and surrounding regions a stress gradient and a zonal pattern of different tectonism away from the trench axis has been postulated pure thrust faulting occurs in the fore arc side while the back arc side is mainly dominated by almost n s extensional tectonics a narrow belt of strike slip faults with predominantly thrust component separates these tectonic zones this belt seems to represent a transition from the thrust type faults to normal faults fault plane solutions of the whole region in question indicate that both the large and small magnitude shocks are caused by the same regional stress field a body of 33 focal mechanisms indicates that the intermediate depth shocks along the sinking mediterranean slab are associated with thrust type fracturing orientation of kinematic axes favours the suggestion that shear zones within the descending slab cause these shocks the active crustal shortening along the hellenic consuming boundary and the sinking of the mediterranean lithosphere beneath the south aegean area explain satisfactorily the seismotectonic features of the fore arc and the southern back arc sides on the contrary geophysical evidence concerning the cenozoic geodynamic evolution of the aegean is needed to interpret features of the north back arc area

seismic strain rates in regions of distributed continental deformation we compare the rates and configurations of seismic deformation determined from moment tensor mechanisms of earthquakes in five continental regions with the rates and configurations expected if the seismicity reflected the relative plate motions in the regions the five regions the aegean iran california western new guinea and central asia are characterized by high levels of seismicity distributed over hundreds to thousands of kilometers from the accepted plate boundaries the earthquake mechanisms are compiled primarily from the catalog of centroid moment tensor solutions which is nearly complete over the interval 1977 1987 for earthquakes greater than ms 5 the thickness of the seismogenic layer in each region is constrained by the results of modeling broadband body wave phases and of previous earthquake studies in the aegean california and western new guinea the observed configurations of deformation agree with a simple model of distributed accommodation of relative plate motion in iran and central asia the moment tensors indicate that there is appreciable strain parallel to the strikes of the belts we augment our 10 year estimates of seismic deformation with the available historical moment and magnitude estimates for the five regions and find that moderate and large earthquakes account for between 25 and 70 of the deformation of the seismogenic layer

currents water masses eddies and jets in the mediterranean levantine basin abstract hydrographic measurements in the southeastern levantine basin are analyzed and the climatological water masses of the region and their seasonal variations are identified we observe the formation of the salty and warm levantine surface water layer lsw we characterize the subsurface atlantic water layer aw and we describe the properties of the thermocline waters called levantine intermediate waters liw the baroclinic dynamical modes are computed for the climatological stratification parameters the empirical orthogonal function eof analysis of the vertical shear profiles shows that considerable energy is contained in the second eof at the thermocline and deep levels maps of the baroclinic streamfunction field referred to 700 meters are displayed 16 instantaneous flow field realizations show an intense mesoscale eddy file never revealed before in the region the space scales of the eddies are about 100 km and a smaller scale 60 70 km variability is also evident the eddies are pres