present day kinematics of the mediterranean a comprehensive overview of gps results i combine recently published gps results to derive a geodetic horizontal velocity field consistent at the scale of the mediterranean and the surrounding alpine belts the velocity field is then used to discuss the boundary conditions around each major deforming area in the mediterranean to describe the main patterns of motion and deformation to critically review the existing kinematics models and to finally point out the main unresolved kinematics questions strain rate in europe north of the alpines belt is dominated by the signature of the glacial isostatic adjustment and tectonic strain remains below the current accuracy of gps results in the western mediterranean deformation is restricted to the betics the alboran and the morrocan rif with west to southwestward motion with respect to iberia which is part of stable europe shortening consistent with the relative nubia eurasia plate motion is found throughout the maghrebides but the distribution of deformation in northern africa remains largely unknown the central mediterranean is dominated by the counter clockwise rotation of the adriatic the junction between the southern adriatic domain and nubia has yet to be firmly established the deformation over a wide area east of the maghrebides in tunisia and the gulf of sirte in libya still remains to be quantified in the eastern mediterranean the velocity field is dominated by a general anti clockwise rotation and a general trend towards the hellenic trench with velocity magnitude increasing with decreasing distances from the trench this trend is observed not only in the aegean and anatolia but also in the southern balkans geodetic results emphasize that the convergence of the nubia and arabia plates towards eurasia directly controls the deformation across only very few segments along the plate boundary zone additional processes are therefore required to explain the observed velocity field and deformation pattern

seismic and volcanic activities and aseismic movements as plate motion components in the aegean area abstract slip rates varying between 0 22 and 2 18 cm yr 1 are determined from seismicity in several segments of the aegean fore arc and back arc regions the rate along the main zone of plate interaction is about 0 5 cm yr 1 while aseismic slip rate equal to 2 5 or 0 5 cm yr 1 depending on the plate motion rate assumed indicates that at least 50 of the plate motion is accommodated by creep these values with respect to the rate of volcanic eruption 0 13 eruptions per year 1000 km of arc length reinforce the suggestion that active volcanism in subduction zones is related to aseismic subduction the eruption rate is however anomalously low with respect to the degree of plate decoupling 0 83 or 0 5 implying that volcanism is not necessarily related to the degree of decoupling and suggesting that the high aseismic slip component of the plate motion is taken up by subcrustal seismicity a tentative hypothesis is made that the hellenic subduction zone is of intermediate type between the marianas and chile subduction types

evidence of large scale deformation patterns from gps data in the italian subduction boundary abstract we present the velocity field in italy derived from over 300 continuous gps stations operated in the 1998 2009 time span the gps network maps the whole country with a mean inter site distance of about 50 km and provides a valuable source of data to study the ongoing deformation processes in the central mediterranean the estimated horizontal and vertical velocity fields show major significant features and also less known second order kinematic features a general uplift characterizes the whole apennines and alpine belts that follow the topographic ridge whereas the po plain shows a gradually increasing subsidence from west to east the apennines belt displays a distinctive extension 50 80 10 9 yr 1 while compressive tectonic regimes characterize northern sicily eastern alps and the northeast front of the northern apennines 25 50 10 9 yr 1 second order deformation patterns on large scale wavelength 100 km have been detected on the accretionary prism of central and southern apennines that are highly correlated with other geophysical data vp anomalies seismic anisotropy etc and related to deep rooted sections 70 100 km marked by different subduction regimes apparently at this scale length the observed deformations are governed by the lithosphere as a whole we interpret these deformations as a result of different subduction mechanisms such as variations of the subduction rollback velocity affecting different segments of the subduction zone and or to mantle flows in proximity of the slab edges further south in central southern sicily we detect a contraction of 1 1 0 2 mm yr that probably accommodates part of the africa eurasia convergence on the outer thrust front of the apennines maghrebides belt this hypothesis agrees with an independent analysis of the seismicity associated to the sicilian basal thrust thought to be still active the itrf2005 estimates of the new gps velocity field are available also in sinex format as supplementary file s1

active tectonics of the algerian atlas mountains evidence from aftershocks of the 1980 el asnam earthquake summary the el asnam algeria earthquake of 1980 october is the largest earthquake to have occurred in north africa since instrumental records began ms 7 3 it was caused by movement on a segmented reverse fault which is part of the fault zone that separates the chelif alluvial plains from the coastal range of the atlas mountains the coastal range is the actively deforming plate boundary between africa and eurasia in this paper the results of an aftershock study carried out using a 28 station portable network in the epicentral area in the 5 weeks after the main shock are presented a total of 4517 aftershocks have been located using both p and s phases of these 4517 events 1279 pass a set of quality criteria and are used to discuss the detailed tectonics of the aftershock zone the southwestern half of the aftershock zone has a relatively restricted band of seismicity running parallel to the main fault in cross section this seismicity is observed to lie almost exclusively in the footwall of the main fault and indicates both antithetic reverse faulting and extension parallel to the fault zone the only exception to this pattern occurs at a junction of the main fault segments where a distinct cluster of events with very variable focal mechanisms is located in the hangingwall this cluster may be equated with a barrier that impeded the rupture of the main shock beyond the southwest end of the main fault a mixture of strike slip and reverse faulting occurred and suggests a mechanism whereby this end of the fault can act as an asperity for earthquake generation aftershocks in the northeastern half of the study area indicate movement on a stack of listric reverse faults the focal mechanisms of these events show that the n dipping nodal planes assumed to be the fault planes flatten with depth we suggest that the faults sole into a low angle 20 decollement at about 8 10 km depth at the base of the aftershock zone we argue that the northeastern part of the 1980 aftershock zone is typical of the actively deforming coastal belt of northwest algeria subduction of the western mediterranean basin beneath the north african margin does not seem to occur instead the margin is absorbing the motion with old normal faults being reactivated as thrusts

a recent tectonic reorganization in the south central mediterranean abstract new geodetic data combined with seismicity geologic and geochemical information document a major tectonic reorganization in the central mediterranean around 0 8 0 5 ma when rapid trench migration and consequent tyrrhenian back arc extension which dominated the region s evolution since the tortonian 10 8 ma essentially stopped in response the african convergence in sicily was transferred to a back thrust in the southern tyrrhenian characterized by frequent m5 6 earthquakes in the last 20 years a diffuse transform boundary formed across northeastern sicily to connect the sicilian and calabrian plate boundaries causing opening of the messina straits home to large historical earthquakes and unusual volcanism in the aeolian island arc and the intraplate mount etna a divergence of the ionian region from the main part of africa with northeastward motions that reflect the joint influence of african push and hellenic slab pull and are transmitted to calabria and adria could explain motions observed in the sicily channel calabria and apulia as well as the high level of southeastern sicilian seismic activity

new constraints on the active tectonic deformation of the aegean 1 site velocities from six separate global positioning system gps networks comprising 374 stations have been referred to a single common eurasia fixed reference frame to map the velocity distribution over the entire aegean we use the gps velocity field to identify deforming regions rigid elements and potential microplate boundaries and build upon previous work by others to initially specify rigid elements in central greece the south aegean anatolia and the sea of marmara we apply an iterative approach tentatively defining microplate boundaries determining best fit rigid rotations examining misfit patterns and revising the boundaries to achieve a better match between model and data short term seismic cycle effects are minor contaminants of the data that we remove when necessary to isolate the long term kinematics we find that present day aegean deformation is due to the relative motions of four microplates and straining in several isolated zones internal to them the rms misfit of model to data is about 2 sigma very good when compared to the typical match between coseismic fault models and gps data the simplicity of the microplate description of the deformation and its good fit to the gps data are surprising and were not anticipated by previous work which had suggested either many rigid elements or broad deforming zones that comprise much of the aegean region the isolated deforming zones are also unexpected and cannot be explained by the kinematics of the microplate motions strain rates within internally deforming zones are extensional and range from 30 to 50 nanostrain year nstrain year 10 9 year 1 to 2 orders of magnitude lower than rates observed across the major microplate boundaries lower strain rates may exist elsewhere within the microplates but are only resolved in anatolia where extension of 13 4 nstrain year is required by the data our results suggest that despite the detailed complexity of active continental deformation revealed by seismicity active faulting fault geomorphology and earthquake fault plane solutions continental tectonics at least in the aegean is to first order very similar to global plate tectonics and obeys the same simple kinematic rules although the widespread distribution of aegean seismicity and active faulting might suggest a rather spatially homogeneous seismic hazard the focusing of deformation near microplate boundaries implies the highest hazard is comparably localized

linear and nonlinear relations between relative plate velocity and seismicity relationships between relative plate velocity and seismicity differ by plate boundary class we test the null hypothesis of linearity of earthquake rates with velocity in each of seven classes a linear relationship is expected if earthquake rate is proportional toseismicmoment rate whichis proportional torelative platevelocity to reducebiasbyaftershocksandswarms weestimateindependenceprobabilitiesofearth quakes and use them as weights we assign shallow earthquakes to boundary steps and classes thensortboundarystepswithineachclassbyvelocityandplotcumulativeearth quakesagainstcumulativemodelmomentrate weusetwomeasuresofnonlinearityand 10 4 stochastic simulations to assess significance in subduction zones the relationship betweenseismicityandvelocityisnonlinearwith99 9 confidence slowersubduction at 66 mm a producing35 oftectonicmomentunderthenullhypothesis produces only 20 of subduction earthquakes continental convergent boundaries display simi larnonlinearity p 0 001forthenullhypothesis oceanspreadingridgesshowseis micity decreasing with velocity oceanic transform faults and oceanic convergent boundaries show marginal nonlinearity p 0 01 p 0 05 continental rifts and continental transform faults follow the null hypothesis three effects may contribute to velocity dependence in subduction 1 the brittle ductile transition at a critical tem peratureisadvecteddeeperbyfasterunderthrusting 2 subductedsedimentisviscous so lower stresses in slower boundaries discourage earthquakes 3 pore pressures increase with velocity encouraging frictional failure mechanism 1 has only minor effects on earthquake productivity but mechanisms 2 and 3 could be important online material earthquake subcatalogs and cumulative distribution tables

active intraplate deformation within adria examples from the adriatic region abstract recent seismicity recorded in the adriatic region suggests that active deformation occurs within the adria plate earthquakes are common in the adjoining chains and in particular along the northern apennines in the southern alps and along the dinaric albanian hellenic thrust fronts in addition medium to low grade seismicity also affects the foreland and is clustered along two main transects through the centre of the adriatic region the two zones of active deformation correspond to the mid adriatic ridge and the gargano region and approximately trend nw se and e w respectively several interpretations have been proposed to explain the deformation observed within the adriatic foreland including a variety of contrasting kinematic and geodynamic models we attempted to unravel the complicated structural evolution of the central adriatic region by interpreting industrial and ministerial shallow and deep seismic profiles and the recent seismicity recorded in the adriatic the subsurface study allowed us to better understand the structural style timing and rates of deformation affecting the mid adriatic ridge and the gargano region and to unravel the relationships of active deformation with respect to the adjacent chains the results of our study indicate that the structural setting and type of seismicity of the central adriatic can be explained in terms of active intraplate deformation with the reactivation of inherited discontinuities

faulting associated with historical and recent earthquakes in the eastern mediterranean region summary this paper summarizes evidence for surface faulting in historical and recent earthquakes in the eastern mediterranean region and in the middle east such information is particularly important for studies of active tectonics and for palaeoseismology we have found 78 cases of faulting pre 1900 and 72 post 1900 some of which show that faults that have apparently been inactive this century had already ruptured before 1900 for some cases faulting could not have been predicted from 20th century activity and in others it could have been expected but has not been observed during the instrumental period the data are suycient to allow the derivation of relationships between magnitude and rupture length

the quest for the africa eurasia plate boundary west of the strait of gibraltar the missing link in the plate boundary between eurasia and africa in the central atlantic is presented and discussed a set of almost linear and sub parallel dextral strike slip faults the swim1 faults that form a narrow band of deformation over a length of 600 km coincident with a small circle centred on the pole of rotation of africa with respect to eurasia was mapped using a new swath bathymetry compilation available in the area offshore sw portugal these faults connect the gloria fault to the rif tell fault zone two segments of the plate boundary between africa and eurasia the swim faults cut across the gulf of cadiz in the atlantic ocean where the 1755 great lisbon earthquake m 8 5 8 7 and tsunami were generated providing a new insight on its source location

shells a thin shell program for modeling neotectonics of regional or global lithosphere with faults the thin plate method of modeling neotectonics uses isostasy and vertical integration of lithospheric strength to reduce three dimensional problems to two dimensions we introduce new thin shell continuum elements and fault elements which satisfy the completeness and compatibility requirements and permit extension of these methods to the lithospheres of spherical planets even a coarse grid of these elements with elastic rheology can reproduce low order toroidal free oscillations in the program shells a realistic frictional dislocation creep rheology is handled by iteration this method converges to solutions which can be numerically tested to confirm that they satisfy both local equilibrium and the balance of torques on whole plates because this code can incorporate both natural plate shapes with internal faults and realistic rheologies it yields models that are readily tested by their predictions of geodetic velocities stresses and fault slip rates

magnetic polarity stratigraphy and carboniferous paleopole positions from the joggins section cumberland structural basin nova scotia one hundred seventy seven samples were taken in stratigraphic sequence in redbeds from approximately 2100 m of namurian westphalian strata from the shepody enrage boss point and lower joggins formations between minudie and joggins nova scotia for the purpose of constructing a magnetic polarity stratigraphy in addition five samples from each of four sites were taken from north dipping strata of the cumberland group for the purpose of conducting a fold test for the joggins formation this yields a total coverage of 412 samples from approximately 2400 m of south dipping strata in the composite section when combined with previous results from the maringouin peninsula divenere and opdyke 1990 and 88 samples from north dipping strata collected for the purpose of conducting fold tests two components of magnetization are identified in these sediments a prefolding component termed c and a synfolding component termed b the present results extend the mid carboniferous magnetic polarity stratigraphy to include eight normal and eight reversed magnetozones in the namurian a through early westphalian a interval the results are dominantly to completely reversed in samples from the remainder of the westphalian a and the westphalian b but because of the complication of varying degrees of remagnetization and an 800 m sampling gap it is not possible to verify the base of the permo carboniferous reversed superchron in this time period northward plate motion is inferred from an observed shallowing of inclinations upsection a 5 7 cm yr average poleward drift rate is calculated for this time period from these results yielding a low latitude southern hemisphere paleogeographic position

computer simulations of california tectonics confirm very low strength of major faults recent improvements in the technique of modeling fault networks with thin plate finite elements yield full convergence of the solutions without any compromise in the representation of the frictional rheology of the upper crust or the transition to dislocation creep in the lower crust we apply these techniques to model the california region incorporating all faults with estimated slip rate over 1 mm yr as well as variations in elevation heat flow and crustal thickness velocity boundary conditions on the model sides are based on the nuvel 1 plate model and an approximation of deformation in the great basin the frictional and dislocation creep rheologic constants of the crust are calibrated to reproduce the observed variations in the maximum depth of seismicity which occurs at model temperatures of 350 410 c this leaves two free parameters the time averaged coefficient of friction on faults and the apparent activation energy for creep in the lower crust these parameters are systematically varied in three sets of 10 81 and 64 experiments respectively the predictions of each model are tested against three published data sets a set of 79 geologic limits on average slip rate on faults a set of 221 principal stress directions and a set of 841 secular rates of geodetic baselines both trilateration and vlbi very long baseline interferometry the patterns of model scores indicate that the time averaged friction coefficient of major faults is only 0 17 0 25 or only 20 30 of the value 0 85 that is assumed for the friction in the intervening blocks the laser trilateration data taken alone would indicate a preference for a high stress model but this model is one with very little fault slip and seismicity which can be rejected on other grounds in the final three parameter set of 64 models we test whether the anomalous weakness of faults is uniform or proportional to net slip with slip dependent weakening there is a general reduction in prediction errors which supports the hypothesis the geologic data and geodetic data agree in implying that fault weakness that is friction of 0 17 is general with an additional 30 slip dependent weakening of the san andreas to friction of 0 12 or 14 of normal the stress data however are fit best if all weakness is slip dependent effectively only the san andreas is weak thus the hypothesis that all weakening is slip dependent should not be rejected the best models predict all available data with rms root mean square mismatch of as little as 3 mm yr 6 of the relative plate velocity so their predictions may be useful for seismic hazard estimation at least along faults where no data are available this study extends the finding of very low friction from subduction zones where it was previously documented to a dominantly strike slip system in which underthrusting of wet sediment is not widespread return of previously subducted water from the mantle and its chemical or physical binding in fine grained gouge are possible explanations for the very low friction

seismicity of the adriatic microplate abstract the adriatic microplate was previously considered to be a unique block tectonically active only along its margins the seismic sequences that took place in the basin from 1986 to 1990 give new information about the geodynamics of this area three subsets of well recorded events were relocated by the joint hypocentre determination technique on the whole this seismic activity was concentrated in a belt crossing the southern adriatic sea around latitude 42 in connection with regional e w fault systems some features of this seismicity similar to those observed in other well known active margins of the adriatic plate support a model of a southern adriatic lithospheric block detached from the northern one other geophysical information provides evidence of a transitional zone at the same latitude

mantle dynamics in the mediterranean the mediterranean offers a unique opportunity to study the driving forces of tectonic deformation within a complex mobile belt lithospheric dynamics are affected by slab rollback and collision of two large slowly moving plates forcing fragments of continental and oceanic lithosphere to interact this paper reviews the rich and growing set of constraints from geological reconstructions geodetic data and crustal and upper mantle heterogeneity imaged by structural seismology we proceed to discuss a conceptual and quantitative framework for the causes of surface deformation exploring existing and newly developed tectonic and numerical geodynamic models we illustrate the role of mantle convection on surface geology a coherent picture emerges which can be outlined by two almost symmetric upper mantle convection cells the downwellings are found in the center of the mediterranean and are associated with the descent of the tyrrhenian and the hellenic slabs during plate convergence these slabs migrated backward with respect to the eurasian upper plate inducing a return flow of the asthenosphere from the backarc regions towards the subduction zones this flow can be found at large distance from the subduction zones and is at present expressed in two upwellings beneath anatolia and eastern iberia this convection system provides an explanation for the general pattern of seismic anisotropy in the mediterranean first order anatolia and adria microplate kinematics and may contribute to the high elevation of scarcely deformed areas such as anatolia and eastern iberia more generally the mediterranean is an illustration of how upper mantle small scale convection leads to intraplate deformation and complex plate boundary reconfiguration at the westernmost terminus of the tethyan collision

tethys atlantic interaction along the iberia africa plate boundary the betic rif orogenic system abstract initial se dipping slow subduction of the ligurian tethys lithosphere beneath africa from late cretaceous to middle oligocene twisting to a later faster e dipping subduction of the subcrustal lithosphere is proposed as an efficient geodynamic mechanism to structure the arcuate betic rif orogenic system this new subduction related geodynamic scenario is supported by a kinematic model constrained by well dated plate reconstructions tectonic sedimentary and metamorphic data sets the slow initial se dipping subduction of the ligurian tethys realm beneath the malaguide upper plate unit is sufficient to subduct alpujarride and nevado filabride rocks to few tens of kilometers of depth in middle eocene times the shift from se to e dipping subduction during latest oligocene early miocene was possibly caused by both the inherited geometry of the highly segmented ligurian tethys domain and by the fast roll back of the subducted lithospheric slab the early miocene rather synchronous multiple crustal and subcrustal processes comprising the collision along the betic front the exhumation of the hp lt metamorphic complexes the opening of the alboran basin its flooring by hp alpujarride rocks and subsequent ht imprint can be explained by the fast nw and w directed roll back of the ligurian tethys subcrustal lithospheric slab the w retreat of the ligurian tethys lithosphere in middle late miocene times could partly explain the initiation of its lateral tear and consequent subcrustal processes from latest miocene onward the betic rif system evolved under both the northerly push of africa resulting in tightening at crustal and subcrustal levels and by the distinct current dynamics of the steep lithospheric slab the sw directed scape of the rif fold belt is one of the most striking evidences linked to the recent evolution of the squeezed betic rif system between africa and iberia

digital isochrons of the world s ocean floor we have created a digital age grid of the ocean floor with a grid node interval of 6 arc min using a self consistent set of global isochrons and associated plate reconstruction poles the age at each grid node was determined by linear interpolation between adjacent isochrons in the direction of spreading ages for ocean floor between the oldest identified magnetic anomalies and continental crust were interpolated by estimating the ages of passive continental margin segments from geological data and published plate models we have constructed an age grid with error estimates for each grid cell as a function of 1 the error of ocean floor ages identified from magnetic anomalies along ship tracks and the age of the corresponding grid cells in our age grid 2 the distance of a given grid cell to the nearest magnetic anomaly identification and 3 the gradient of the age grid i e larger errors are associated with high age gradients at fracture zones or other age discontinuities future applications of this digital grid include studies of the thermal and elastic structure of the lithosphere the heat loss of the earth ridge push forces through time asymmetry of spreading and providing constraints for seismic tomography and mantle convection models

aegean tectonics strain localisation slab tearing and trench retreat abstract we review the geodynamic evolution of the aegean anatolia region and discuss strain localisation there over geological times from late eocene to present crustal deformation in the aegean backarc has localised progressively during slab retreat extension started with the formation of the rhodope metamorphic core complex eocene and migrated to the cyclades and the northern menderes massif oligocene and miocene accommodated by crustal scale detachments and a first series of core complexes mccs extension then localised in western turkey the corinth rift and the external hellenic arc after messinian times while the north anatolian fault penetrated the aegean sea through time the direction and style of extension have not changed significantly except in terms of localisation the contributions of progressive slab retreat and tearing basal drag extrusion tectonics and tectonic inheritance are discussed and we favour a model 1 where slab retreat is the main driving engine 2 successive slab tearing episodes are the main causes of this stepwise strain localisation and 3 the inherited heterogeneity of the crust is a major factor for localising detachments the continental crust has an inherited strong heterogeneity and crustal scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation the dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate successive slab ruptures from the middle miocene to the late miocene have isolated a narrow strip of lithosphere still attached to the african lithosphere below crete the formation of the north anatolian fault is partly a consequence of this evolution the extrusion of anatolia and the aegean extension are partly driven from below asthenospheric flow and from above extrusion of a lid of rigid crust

experimental evidence for mantle drag in the mediterranean 1 what forces control active deformation in the central mediterranean slab pull has long been debated but no other hypothesis has been generally accepted here we analyze the role of shear basal tractions by using a thin shell modeling technique we generated a large number of models that span different sets of boundary conditions from the literature we then explored acceptable ranges of model parameters we computed residuals between model predictions and several datasets of stress directions gps measurements and tectonic stress regimes that have been produced in recent studies and then compared the best models obtained in the presence of tractions with those obtained in the absence of tractions for all tested boundary conditions and all considered datasets our results show that the only successful models are those with significant basal shear traction exerted by eastward mantle flow

on the mesozoic ionian basin summary new seismic reflection profiles of the italian deep crust project crop provide new insights on the structure of the ionian sea in spite of the apennines and hellenides neogene subduction zones two conjugate passive continental margins are preserved at the margins of the ionian sea along the malta escarpment to the southwest and the apulian escarpment to the northeast the ionian sea is likely to be a remnant of the mesozoic tethys ocean confined by these two conjugate passive continental margins the transition from continental to oceanic crust appears sharper to the northeast than to the southwest the basin between southeast sicily and southwest puglia was about 330 km wide and suggests a low spreading rate the inferred oceanic ridge should have been flattened by thermal cooling and buried by later sediments based on stratigraphic and structural constraints to the north in the apennines belt the ocean continued to the northwest this palaeogeography is supported by the seismicity of the apennines slab underneath the southern tyrrhenian sea which implies downgoing oceanic lithosphere the adjacent absence or paucity of deep seismicity does not imply absence of subduction but rather it can be interpreted as due to the more ductile behaviour of the subducted continental lithosphere surprisingly we note that where the oceanic inherited basin is subducting underneath the apennines in the hangingwall of the subduction hinge there are outcropping slices of continental crystalline basement previously deformed by the alpine orogen

the cephalonia transform fault and its extension to western lefkada island greece the central area of the ionian islands is dominated by the existence of a major tectonic structure called the cephalonia transform fault ctf its main part cephalonia segment has been identified by previous work based on the spatial distribution of earthquake foci fault plane solutions of strong earthquakes active tectonics structural studies and geodetic measurements this part cephalonia segment which exhibits strike slip motion with a thrust component strikes in a northeast direction dips to the southeast and has a length of 90 km in the present paper information concerning new fault plane solutions orientation of isoseismals sea bottom topography and recent gps results are used to further check the properties of this southern part of the ctf and to explore its northeastward prolongation to lefkada island it is shown that the ctf is extended to the western coast of lefkada this northern branch lefkada segment of the ctf which is also characterized by strike slip motion with a thrust component strikes in a north northeast direction dips to the east southeast and has a length of 40 km these two segments of the ctf form a major kinematic boundary where the slip rate is 2 3 cm yr

the block like behavior of anatolia envisaged in the modeled and geodetic strain rates 1 the geodetic velocity and strain rate patterns in anatolia constrain the rheology of the lithosphere once compared with thin shell finite element tectonic model predictions geodetic and modeled deformation favors a hard lithospheric rheology responsible for the high east west horizontal velocities in the center of anatolia between 39 41 n in proximity of the north anatolian fault the block like behavior of anatolia due to the hard lithospheric rheology is responsible for the low geodetic and modeled strain rates in the center of the peninsula the low strain rate is well correlated with the region of low release of seismic energy between 33 36 e and 38 40 n the high seismic and geodetic strain rate region in the far west part of the naf is also well reproduced by the modeling

validity of the thin viscous sheet approximation in models of continental collision 1 the two dimensional thin viscous sheet approximation is widely used to describe large scale continental deformation it treats the lithosphere as a fluid layer in which deformation results from a balance between buoyancy forces and tectonic boundary conditions comparisons between two dimensional thin sheet and full three dimensional solutions of a simple indenter model show that appreciable differences exist especially when the indenter half width d is of the same order as the thickness of the deforming layer l i e d l 1 these differences are amplified by increasing the power law exponent of the viscous constitutive law n but decrease as the argand number ar is increased the greatest differences between two dimensional and three dimensional solutions are found at the indenter corner where the thin sheet consistently overestimates vertical strain rates differences between strain rates at the corner may be 50 or greater for small argand numbers other differences arise because a lithospheric root zone is formed in the three dimensional solutions and vertically averaged strain rate is decreased in regions close to the indenter this effect is absent from thin sheet calculations since the thickness of the load bearing layer is assumed constant in general the thin viscous sheet approximation provides a reasonably accurate estimate of long wavelength deformation for d l as low as 1 if n is less than 3 however even at large d l the solutions may be inaccurate close to strain rate concentrations at the indenter corners where horizontal gradients of deformation are large

attached or not attached evidence from crustal stress observations for a weak coupling of the vrancea slab in romania abstract the crustal stress pattern of romania provides key insights into whether the vrancea slab with its seismogenic volume between 70 and 175 km depth is still coupled to the crust and thus acts as a stress guide or whether it is already in a state of detachment from the crust knowledge of the state of the slab under vrancea is particularly critical because the slab attached to the crust can result in future strong earthquake occurrence in the crust and even in the currently aseismic zone between 40 km and 70 km depth potentially causing severe damage our analysis of the contemporary tectonic stress observations in the context of potential stress sources and the comparison with numerical modelling shows that the crustal stress pattern in romania is heterogeneous and does not contain a long wave length stress pattern that would be expected if there is a strong present day coupling between the subducted slab and the upper plate or if lateral plate boundary forces would control the regional stress pattern therefore we conclude that the crustal stress pattern of romania is characterised by small differential horizontal stresses where local stress sources third order effects are responsible for the observed heterogeneity of stress orientations and that the subducted slab under vrancea is only weakly coupled to the crust

bridging onshore and offshore present day kinematics of central and eastern mediterranean implications for crustal dynamics and mantle flow we present a new kinematic and strain model of an area encompassing the calabrian and hellenic subduction zones western anatolia and the balkans using haines and holt s 1993 method we derive continuous velocity and strain rate fields by interpolating geodetic velocities including recent gps data in the balkans relative motion between stable eurasia and the western aegean sea is gradually accommodated by distributed n s extension from southern balkans to the eastern corinth gulf so that the westward propagation of the north anatolian fault naf throughout continental greece or peloponnesus is not required we thus propose that the naf terminates in north aegean and that n s extension localized in the corinth gulf and distributed in southern balkans is due to the retreat of the hellenic slab the motion of the hyblean plateau apulia peninsula south adriatic sea ionian basin and sirte plain can be minimized by a single rigid rotation around a pole located in the sirte plain compatible with the opening the pelagian rifts 2 2 5 mm yr and seismotectonics in libya we interpret the trenchward ultraslow motion of the calabrian arc 2 2 5 mm yr as pure collapse the calabrian subduction being now inactive in the absolute plate motion reference frame our modeled velocity field depicts two toroidal crustal patterns located at both ends of the hellenic subduction zone clockwise in nw greece and counter clockwise in western anatolia we suggest the nw greece toroidal pattern is the surface expression of a slab tear and consequent toroidal asthenospheric flow

a new intracontinental transcurrent structure the central anatolian fault zone turkey abstract recent neotectonic studies including remote sensing aerial photographs geological field mapping on various scales and measured stratigraphic section substantiate the existence of a large sinistral intracontinental transcurrent structure which we call the central anatolian fault zone cafz this is an approximately 730 km long 2 km to 80 km wide ne trending active sinistral strike slip fault zone that cuts across the anatolian plateau between duzyayla in the northeast and anamur county in the southwest it continues onward beneath the eastern mediterranean sea and determines the boundary of the antalya and adana basins as far as to the west of cyprus the cafz is a very young neotectonic structure it resulted from the reactivation and propagation of an older paleotectonic structure the so called ecemi s corridor in both nne and sw directions across the inner tauride suture in the plio quaternary times based on geometric discontinuities the cafz is divided into 24 segments each of them is characterized by a number of strike slip morphotectonic features reflecting recent motions the easternmost part of the anatolian platelet is being deformed internally by several dextral to sinistral intraplate strike slip faults these are the lake salt fault zone lsfz the salanda fault sf the cafz the goksu yazyurdu fault zone gyfz and the malatya ovacik fault zone mofz they take up lesser motion and are younger than boundary faults of the anatolian platelet the gyfz and mofz splay from the natf cut across the anatolian platelet and then meet to the eatf whereas other faults are confined into the anatolian platelet and seem to be independent structures however present day structural pattern of all these intraplate faults and boundary faults of the anatolian platelet indicates a regional strain pattern of nnw sse directed shortening and ene wsw directed extension and they seem to have developed to accommodate northward motion of the arabian plate since late early pliocene times

sks splitting in southern italy anisotropy variations in a fragmented subduction zone abstract in this paper we present a collection of good quality shear wave splitting measurements in southern italy in addition to a large amount of previous splitting measurements we present new data from 15 teleseisms recorded from 2003 to 2006 at the 40 stations of the cat scan temporary network these new measurements provide additional constraints on the anisotropic behaviour of the study region and better define the fast directions in the southern part of the apulian platform for our analysis we have selected well recorded sks phases and we have used the method of silver and chan to obtain the splitting parameters the azimuth of the fast polarized shear wave and delay time t shear wave splitting results reveal the presence of a strong seismic anisotropy in the subduction system below the region three different geological and geodynamic regions are characterized by different anisotropic parameters the calabrian arc domain has fast directions oriented nne ssw and the southern apennines domain has fast directions oriented nnw sse this rotation of fast axes following the arcuate shape of the slab is marked by a lack of resolved measurements which occurs at the transition zone between those two domains the third domain is identified in the apulian platform here fast directions are oriented almost n s in the northern part and nne ssw to ene wsw in the southern one the large number of splitting parameters evaluated for events coming from different back azimuth allows us to hypothesize the presence of a depth dependent anisotropic structure which should be more complicated than a simple 2 layer model below the southern apennines and the calabrian arc domains and to constrain at 50 km depth the upper limit of the anisotropic layer at least at the edge of southern apennines and apulian platform we interpret the variability in fast directions as related to the fragmented subduction system in the mantle of this region the trench parallel observed in calabrian arc and in southern apennines has its main source in the asthenospheric flow below the slab likely due to the pressure induced by the retrograde motion of the slab itself the pattern of in the apulian platform does not appear to be the direct result of the rollback motion of the slab whose influence is limited to about 100 km from the slab the anisotropy in the apulian platform may be related to an asthenospheric flow deflected by the complicated structure of the adriatic microplate or may also be explained as frozen in lithospheric anisotropy

a crustal model for the eastern alps region and a new moho map in southeastern europe in the last two decades south central europe and the eastern alps have been widely explored by many seismic refraction experiments e g celebration 2000 alp 2002 sudetes 2003 although quite detailed images are available along linear profiles a comprehensive three dimensional crustal model of the region is still missing this limitation makes this region a weak spot in continental wide comprehensive representations of crustal structure to improve on this situation we select and collect 37 published active source seismic lines in this region after geo referencing each line we sample them along vertical profiles every 50 km or less along the line and derive p wave velocities in a stack of homogeneous layers separated by discontinuities depth of crystalline basement top of lower crust and moho we finally merge the information using geostatistical methods and infer s wave velocity and density using empirical scaling relations we present here the resulting crustal model for a region encompassing the eastern alps dinarides pannonian basin western carpathians and bohemian massif covering the region within 45 circ text 51 circ hbox n and 11 circ text 22 circ hbox e with a resolution of 0 2 circ times 0 2 circ we are also able to extend and update the map of moho depth in a wider region within 35 circ text 51 circ hbox n and 12 circ text 45 circ hbox e gathering moho values from the collected seismic lines other published dataset and using the european plate reference epcrust as a background all the digitized profiles and the resulting model are available online

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

active thrusting as a possible seismogenic source in sicily southern italy some insights from integrated structural kinematic and seismological data abstract this paper proposes a new seismogenic interpretation of mainland and central southern sicily based on an integrated structural kinematic seismological approach through analysis of available structural and geophysical data the tectonic setting the major kinematic units and the crust geometry of the sicilian southward verging fold and thrust belt system are schematized in sections and in map form the depth contour lines of the outermost basal thrust plane which dates back to plio pleistocene times with some evidence of holocene activity are reconstructed this plane here named sicilian basal thrust sbt emerges along the southward convex sciacca gela catania front and reaches the base of the crust at a depth of about 30 km beneath northern sicily additionally an important regional upper crust splay with the same arched shape has been identified some kilometres northward in order to detect any possible indication of seismogenic activity linked to ongoing deformation of the sbt and its splay we analyzed the distribution and kinematics of the instrumental seismicity in the period between 1981 and 2006 particular attention was given to the background seismicity ml up to 4 6 located beneath the sedimentary cover at mt etna as it allows individuating a northward deepening seismogenic volume undergoing an average n s compression which corresponds well with the sbt geometry in section view a merged dataset of all the known major historical and instrumental events moment magnitude 4 5 that occurred above the sbt 0 to 30 km depth contour lines from 217 b c to 2006 was compiled and analyzed based on information from instrumental data and or on speculations on the shape and extent of the historical earthquake macroseismic fields two major ranges of hypocentral depths have been schematically identified within the merged dataset an upper crust range in average

local regional and plate scale sources for the stress field in the adriatic and periadriatic region abstract the stress field at a specific location is the sum of regional stress controlled by plate scale tectonic processes with local sources here we evaluate and discuss the different sources from geodynamic to local scale and the controlling factors including the jurassic paleogeography of the adriatic passive margin of present day stress in the adriatic sea and periadriatic regions of italy using two kinds of numerical models 3d mantle scale viscoelastic models and 2 5d lithosphere scale thin shell models the subcrustal stress field of the slabs in the dinarides hellenic and apennines calabrian subduction zones are characterized by downdip extension and compression respectively this difference is explained by the velocity of the adriatic slab with respect to the upper mantle in the hotspot reference frame the slab in the calabrian subduction zone is encroached and down pushed whereas the slab in the hellenic subduction zone is sustained by the mantle flow at the plate scale the upper crustal stress field at the apennines front is governed by the different nature of the lithosphere probably oceanic in the ionian sea and continental elsewhere which in turn determines first order rotations of the stress axes second order rotations of the stress axes depend on the jurassic paleogeography and consequent differential advancement of the thrust fronts with recesses and salient occurring in correspondence with jurassic structural highs and lows respectively the eastward relative motion of the mantle with respect of the lithosphere enhances the onset of nw se oriented compression within the adriatic plate consistent with observations finally 2 5d thin shell models demonstrate that present day stress does not simply follow the long wavelength pattern 500 1000 km due to plate tectonics and mantle interaction but is greatly affected by the presence of second and third order sources like crustal structure faults and topography most importantly these factors give an observable effect in data

comment on a new intracontinental transcurrent structure the central anatolian fault zone turkey by a kocyigit and a beyhan abstract kocyigit and beyhan have described the central anatolian fault zone cafz as a 700 km long active strike slip fault zone in turkey if their interpretation is correct then several major turkish cities are vulnerable to a significant earthquake hazard which was previously unsuspected and the existing close agreement between observed slip rates on major strike slip faults in turkey and predictions from global plate motion models is spurious whether the cafz is real or based on mistaken interpretations of diverse evidence is thus a matter of some importance the aim of this comment is to describe difficulties which arise over the published interpretation of the cafz with the aim of encouraging either a retraction or a more thorough presentation of the available evidence in support of the existence of a major active fault zone in the required position three main difficulties are discussed in detail first strands of the cafz have been interpreted in many localities where previous detailed studies have either found no evidence of faulting or have reported ancient faults which have been described as no longer active second many other features which previous studies have explained satisfactorily are reinterpreted as consequences of active strike slip faulting finally no observational evidence is presented for the slip rate or the timing of the start of the alleged present phase of slip on the cafz the suggestion that it has slipped by 24 km during this present phase of activity is inadequately documented and conflicts with other evidence

dynamic models of earthquakes on the north anatolian fault zone under the sea of marmara effect of hypocenter location 1 we perform three dimensional spontaneous dynamic rupture models of potential earthquakes on the geometrically complex north anatolian fault zone nafz under the marmara sea turkey the nafz south of the city of istanbul consists of a large scale extensional stepover with right lateral strike slip segments linked by an oblique normal segment we find that earthquakes nucleating near the stepover do not propagate across the entire fault system due to the statically unfavorable stress field on the oblique fault and lead to moderate size events only however earthquakes initiating a significant distance from the stepover cause significant dynamic unclamping of the oblique fault and thus generate large through going ruptures dynamic unclamping also produces supershear rupture propagation in the vicinity of fault discontinuities the results emphasize that estimations of earthquake size rupture propagation and slip distribution cannot be decoupled from the location of the hypocenter and the orientation of the geometrically complex fault system within the tectonic stress field

earthquake induced flooding and paleoseismicity of the el asnam algeria fault related fold late quaternary activity of the el asnam thrust fault responsible for the october 10 1980 ms 7 3 earthquake and 36 km coseismic faulting is explored through diverse paleoseismological field methods we trenched through the main and secondary 1980 coseismic scarps made an analysis of earthquake induced flood deposits conducted a geomorphic study of leveling profiles and offset geological units across thrust and normal scarps and considered the geomorphology of the active fold twenty five radiocarbon ages from colluvial and alluvial deposits along with conventional fossils and artefacts dating of geological units show the timing of successive net vertical displacements on the thrust related fold and bending moment faults previous work showed that eight pre 1980 earthquakes occurred in clusters during the late holocene cumulative net vertical slip that amounts to 3 times the 1980 displacement is observed on multiple thrust fault scarps and offsets of geological units on bending moment faults maximum cumulative vertical displacements which are visible in different zones along the fault segments can reach 10 to 25 times the 1980 coseismic displacements the late quaternary uplift rate on the el asnam fault is 0 6 mm yr and taking into account slip variation along the fault this rate may range between 0 25 1 6 mm yr from which we obtain a shortening rate of 0 17 1 2 mm yr because the tell atlas mountains exhibit comparable seismogenic fault related folds with parallel and sequential structures of active faults a total average shortening rate of 2 05 mm yr during the late quaternary represents part of the convergence accommodated along the africa eurasia plate boundary

new gps constraints on the kinematics of the apennines subduction abstract we present the velocity field of the italian area derived from continuous gps observations from 2003 to 2007 the gps sites were installed by different institutions and for different purposes they cover the whole country with a mean inter site distance of about 60 km and provide a valuable source of data to map the present day kinematics of the region the absolute itrf2005 rotation poles and rates of eurasia africa and adriatic plates are estimated to study the kinematics along their boundaries in the apennines belt the corsica sardinia block coherently moving as the eurasia plate is used as reference of the upper plate for the apennines subduction zone we apply a simple kinematic model to estimate the rates and spatial pattern of the subduction along the apennines we identify at least four different independently moving lower plates i e the adriatic diverging and internally segmented ionian sicily and africa converging plates with different subduction rates the conservative estimates of the subduction rate are 5 mm yr in the calabrian arc 1 5 mm yr in sicily and 0 9 mm yr in the northern apennines this variegate mixture of behaviors seems to reflect the variable lithospheric thickness and composition of the lower plates inherited from the mesozoic rifting an unexpected along strike contraction is observed along the western side of the central northern apennines velocities are estimated both relative to eurasia and relative to the deep and shallow hotspot reference frames hsrf the hotspot representation seems more coherent with the geophysical and geological constraints along the subduction system in which the adriatic and ionian plates move sw ward and their deeper slab portions provide an obstacle to the opposite relative mantle flow all these patterns better reconcile if the subduction process is conceived as a passive feature controlled by the far field plate velocities and the relative eastward mantle flow acting on a disrupted slab

deformation of western turkey from a combination of permanent and campaign gps data limits to block like behavior 1 we present a new geodetic velocity field covering western turkey south of the north anatolian fault our velocity field is derived from a combination of continuously recording gps stations operating since 2003 survey type gps measurements carried out in the period 1997 2005 and velocities from reilinger et al 2006 the velocity field indicates that western turkey currently undergoes extension whose rate increases from the anatolia plateau to the aegean coast the overall extension in westernmost turkey is about 20 mm yr making it one of the fastest areas of continental extension in the world we test whether the observed deformation is better represented by the rotation of crustal blocks or by more distributed deformation while no deformation is detected in the central anatolian plateau we observe a deformation field west of the plateau that cannot be explained by block models unless the blocks are so small as to be essentially indistinguishable from a continuum although concentration of strain rates up to 140 nstrain yr are found across the major grabens strain rates above 50 nstrain yr are found throughout western turkey the distributions of topography and crustal thickness in western turkey agree with the distributions expected if the crust there had a constant thickness at 5 ma equal to that of the present central anatolian plateau and had subsequently been thinned at the present day distribution of strain rates our results therefore suggest that extensional strain affects the whole continental lithosphere of western turkey rather than being restricted to a small number of block boundaries

exploratory models of long term crustal flow and resulting seismicity across the alpine aegean orogen 1 long term crustal flow is computed with a kinematic finite element model based on iterated weighted least squares fits to data and prior constraints data include 773 fault traces 106 fault offset rates 510 geodetic velocities 2566 principal stress azimuths and velocity boundary conditions representing the rigid parts of the eurasia africa and anatolia plates model predictions include long term velocities fault slip rates and distributed permanent strain rates between faults one model assumes that geodetic velocities measured adjacent to the aegean trench reflect a temporarily locked subduction zone in this case long term subduction velocity averages 45 mm yr and rapid crustal extension is predicted in the southern aegean sea another model assumes steady creeping subduction in this case subduction velocity averages only 29 mm yr and the eastern aegean seafloor is predicted to be more nearly rigid long term seismicity maps are computed for each model on the basis of the shift hypotheses and previous global calibrations of plate boundary earthquake production retrospective comparisons to seismic catalogs are encouraging map patterns spatial distribution functions and total earthquake counts are all comparable while neither model accurately predicts earthquake rates at all magnitudes the creeping subduction model is more accurate for strong m6 events which dominate the seismic hazard

melting temperatures of the allende meteorite implications for a hadean magma ocean abstract melting temperatures of the silicate fraction of the allende cv3 meteorite at upper mantle pressures are several hundred degrees lower than that of fertile peridotite xenoliths or pyrolite if the earth accreted from material similar to chondrites then deep mantle melting could have occurred with a relatively modest heat budget it is concluded that initial chemical composition is an important variable in realistic magma ocean models

active tectonics of the adriatic region from gps and earthquake slip vectors 1 to investigate the kinematics of the adriatic region we integrate continuous and episodic gps measurements with mw 4 5 earthquake slip vectors selected from the regional centroid moment tensor catalogue coherent motion of gps sites in the po valley in apulia and in the hyblean plateau allows us to estimate geodetically constrained angular velocities for these regions the predictions of the gps inferred angular velocities are compared with the earthquake slip vectors showing that the seismically expressed deformation at the microplate boundaries is consistent with the observed geodetic motion the remarkable consistency between geodetic seismological and geological evidence of active tectonics suggests that active deformation in the central adriatic is controlled by the relative motion between the adria and apulia microplates the microplates angular rotation rates are then compared with the rotation rates calculated with a simple block model supporting the hypotheses 1 that apulia forms a single microplate with the ionian sea and possibly with the hyblean region and 2 that adria and apulia rotate in such a way as to accommodate the eurasia nubia relative motion we suggest that the present day microplate configuration follows a recent fragmentation of the adriatic promontory that during the neogene rigidly transferred the africa motion to the orogenic belts that now surround the adriatic region

a review of heterogeneous materials and their implications for relationships between kinematics and dynamics in continents 1 the variation of mechanical properties as a function of depth in the lithosphere controls the relationship between surface deformation and whole lithosphere deformation where mechanical competence elastic strength or viscous stiffness is a continuous function with depth surface deformation can be used to constrain either force balance or rheological parameters for the lithosphere however where competence is vertically discontinuous the surface deformation and deformation at depth may have a range of relationships including complete independence therefore both inversions and forward models designed to test either rheology or stress state are highly sensitive to the a priori choice of a mechanical model

convergence vs retreat in southern tyrrhenian sea insights from kinematics 1 the tyrrhenian sea is an extensional basin opened by trench retreat and back arc extension during subduction of the calabrian slab in the last 10 12 my subduction is still active beneath the semost part of the tyrrhenian sea as testified by seismicity down to 500 km depth by analyzing seismicity and geodetic data together with recent tomographic images we define the present day situation an evident n s compressional regime prevails in the tyrrhenian region west of the aeolian archipelago while east of them a nnw sse extension is documented by focal mechanisms and gps data with a much smaller strain rate with respect to the past the transition between these two domains is accommodated by a n s discontinuity zone which runs from aeolian islands to mt etna with an extensional to strike slip deformation

current strain regime in the western alps from continuous global positioning system measurements 1996 2001 four to six years of continuous measurements at 10 permanent global positioning system sites in the western alps show horizontal residual velocities of 2 mm yr with respect to stable europe uncertainties range from 0 3 to 1 4 mm yr these velocities and the associated strain rate field indicate that the central part of the range is currently dominated by east west extension whereas the southern part shows north south to northwest southeast compression the geodetic and seismotectonic data are consistent with a model where strain is essentially controlled by the counterclockwise rotation of the adriatic microplate with respect to eurasia this rotation together with the arcuate shape of the contact between the adriatic microplate and the alps induces dextral shear kinematic boundary conditions across the western alps with an additional divergence component in their central part and in switzerland and a convergence component in their southern part

a re evaluation of the eskisehir fault zone as a recent extensional structure in nw turkey abstract the eskisehir fault zone efz one of the major active structures within the anatolian platelet is investigated in a 100 km long sector between bozuyuk and alpu in vicinity of eskisehir the morphotectonic observations indicate that throughout the studied area the efz extends wnwwards as a ca 15 km wide belt and is composed of some 21 fault segments 5 25 km long these segments form a north dipping southern set and two south dipping northern sets all together working both sides of the eskisehir graben the faults are dominantly normal in character with a slight right lateral component in the westernmost areas the estimated total vertical displacement on certain northern and southern fault segments exceeds 450 m in order to estimate the initiation age of the efz a brief stratigraphic review is given the generally horizontal pliocene terrestrial deposits are separated from the miocene succession by a low angular unconformity and are cut in turn by the efz sedimentological data show that neither the distribution of the pliocene depositional environments and their paleocurrent directions nor the preserved pliocene basal unconformity surface have a genetic relation to the efz these data strongly suggest that the efz is a younger post pliocene active normal fault zone with low rates of deformation

neotectonics and long term seismicity in europe and the mediterranean region we present a neotectonic model of ongoing lithosphere deformation and a corresponding estimate of long term shallow seismicity across the africa eurasia plate boundary including the eastern atlantic mediterranean region and continental europe gps and stress data are absent or inadequate for the part of the study area covered by water thus we opt for a dynamic model based on the stress equilibrium equation this approach allows us to estimate the long term behavior of the lithosphere given certain assumptions about its structure and physics for both land and sea areas we first update the existing plate model by adding five quasirigid plates the ionian sea adria northern greece central greece and marmara to constrain the deformation pattern of the study area we use the most recent data sets to estimate the lithospheric structure the models are evaluated in comparison with updated data sets of geodetic velocities and the most compressive horizontal principal stress azimuths we find that the side and basal strengths drive the present day motion of the adria and aegean sea plates whereas lithostatic pressure plays a key role in driving anatolia these findings provide new insights into the neotectonics of the greater mediterranean region finally the preferred model is used to estimate long term shallow seismicity which we retrospectively test against historical seismicity as an alternative to reliance on incomplete geologic data or historical seismic catalogs these neotectonic models help to forecast long term seismicity although requiring additional tuning before seismicity rates are used for seismic hazard purposes

new gps constraints on active deformation along the africa iberia plate boundary abstract we use velocities from 65 continuous stations and 31 survey mode gps sites as well as kinematic modeling to investigate present day deformation along the africa iberia plate boundary zone in the western mediterranean region the gps velocity field shows southwestward motion of the central part of the rif mountains in northern morocco with respect to africa varying between 3 5 and 4 0 mm yr consistent with prior published results stations in the southwestern part of the betic mountains of southern spain move west southwest with respect to eurasia 2 3 mm yr the western component of betics motion is consistent with partial transfer of nubia eurasia plate motion into the southern betics the southward component of betics motion with respect to iberia is kinematically consistent with south to southwest motion of the rif mountains with respect to africa we use block modeling constrained by mapped surface faults and seismicity to estimate the geometry and rates of strain accumulation on plate boundary structures our preferred plate boundary geometry includes one block between iberia and africa including the sw betics alboran sea and central rif this geometry provides a good fit to the observed motions suggesting a wide transpressive boundary in the westernmost mediterranean with deformation mainly accommodated by the gloria azores fault system to the west and the rif tell lineament to the east block boundaries encompass aspects of earlier interpretations suggesting three main deformation styles i extension along the ne sw trending trans alboran shear zone ii dextral strike slip in the betics corresponding to a well defined e w seismic lineament and iii right lateral strike slip motion extending west to the azores and right lateral motion with compression extending east along the algerian tell we interpret differential motion in the rif alboran betic system to be driven both by surface processes related the africa eurasia oblique convergence and sub crustal dynamic processes associated with the long history of subduction of the neotethys ocean lithosphere the dextral slip identified in the betic mountains in southern spain may be related to the offshore fault that produced the great 1755 lisbon earthquake and as such may represent a significant seismic hazard for the west mediterranean region

anisotropy patterns in the subducting lithosphere and in the mantle wedge a case study the southern italy subduction system 1 in this study we present a collection of high quality s wave splitting measurements in the southern italy subduction system we analyzed 76 deep earthquakes located within the descending slab using the method of silver and chan 1991 to determine the splitting parameters and t the local deep earthquakes allow us to analyze raypaths primarily sampling the slab and the wedge above it mainland calabria is an outcropping forearc enabling us to sample rays that propagate up the slab s wave splitting parameters show a complex pattern of anisotropy with variable fast directions and with delay times ranging from 0 1 s to 2 2 s we compared local s wave splitting data with sks results at the same stations and we found that the average t is very different 1 8 s for sks and 0 5 s for s we found consistency between averaged s fast directions and the sks splitting measurements including a pattern of toroidal mantle flow at the sw edge of the slab the s wave splitting parameters show frequency dependent behavior that we attribute to the presence of small scale anisotropic heterogeneities comparison of s splitting measurements to p wave velocity anomaly at 100 200 km depth shows that where the rays primarily sample the slab the delay times are small in contrast where s rays sample the mantle wedge the delay times are quite high this t pattern depicts the slab as a weakly anisotropic region and suggests that the main source of anisotropy in the subduction zone is the surrounding asthenosphere

fault slip rates for the active external dinarides thrust and fold belt 1 we present estimates of slip rates for active faults in the external dinarides this thrust and fold belt formed in the adria eurasia collision zone by the progressive formation of ne dipping thrusts in the footwalls of older structures we calculated the long term horizontal velocity field slip rates and related uncertainties for active faults using a thin shell finite element method we incorporated active faults with different effective fault frictions rheological properties appropriate geodynamic boundary conditions laterally varying heat flow and topography the results were obtained by comparing the modeled maximum compressive horizontal stress orientations with the world stress map database the calculated horizontal velocities decrease from the southeastern external dinarides to the northwestern parts of the thrust and fold belt this spatial pattern is also evident in the long term slip rates of active faults the highest slip rate was obtained for the montenegro active fault while the lowest rates were obtained for active faults in northwestern slovenia low slip rates influenced by local active diapirism are also characteristic for active faults in the offshore central external dinarides these findings are contradictory to the concept of adria as an internally rigid aseismic lithospheric block because the faults located in its interior release a part of the regional compressive stress we merged the modeling results and available slip rate estimates to obtain a composite solution for slip rates

foreland segmentation along an active convergent margin new constraints in southeastern sicily italy from seismic and geodetic observations abstract we performed an in depth analysis of the ongoing tectonics of a large sector of southern sicily including the hyblean foreland and the front of the maghrebian chain as well as the ionian sea offshore through the integration of seismic and gps observations collected in the nearly two decades in particular a dataset consisting of more than 1100 small to moderate magnitude earthquakes 1 0 ml 4 6 has been used for local earthquake tomography in order to trace the characteristics of the faulting systems and for focal mechanisms computation to resolve the current local stress field and to characterise the faulting regime of the investigated area in addition gps measurements carried out on both episodic and continuous stations allowed us to infer the main features of the current crustal deformation pattern main results evidence that the hyblean plateau is subject to a general strike slip faulting regime with a maximum horizontal stress axis nw se to nnw sse oriented in agreement with the eurasia nubia direction of convergence the plateau is separated into two different tectonic crustal blocks by the left lateral strike slip scicli ragusa fault system the western block moves in agreement with central sicily while the eastern one accommodates part of the contraction arising from the main eurasia nubia convergence furthermore we provided evidences leading to consider the hyblean maltese escarpment fault system as an active boundary characterised by a left lateral strike slip motion separating the eastern block of the plateau from the ionian basin all these evidences lend credit to a crustal segmentation of the southeastern sicily

european mediterranean regional centroid moment tensor catalog solutions for years 2001 and 2002 abstract we present regional centroid moment tensor rcmt solutions for 168 moderate magnitude earthquakes that occurred in the european mediterranean region during 2001 and 2002 events with moment magnitudes as low as 4 0 were successfully analyzed although this low threshold is only achievable in regions with the best azimuthal coverage and with stations at a few hundred kilometers distance earthquakes with focal depths from 10 to more than 200 km were analyzed comparison with standard harvard cmts when available shows good agreement the solutions shown in this paper represent an addition to the european mediterranean rcmt catalog that we are maintaining the rcmt catalog now spans 6 years from 1997 to 2002 and contains 420 solutions we also outline the main seismic sequences that occurred in the european mediterranean region during 2001 2002

recent and active tectonics in the calabrian arc southern italy normal faulting which has developed since the middle pleistocene with an overall ese wnw extension is the dominant mode of deformation which has characterized the calabrian arc up to the present quaternary normal faults extend for a total length of about 180 km along the inner side of the arc the different normal fault segments which during the pleistocene controlled the evolution of the main marine sedimentary basins are varying in length from 10 to 20 km and have fault escarpments showing a very young morphology which define the fronts of the major mountain ranges of the arc the morphological features of the fault escarpments suggest slip rates of 0 8 1 1 mm yr for the last 700 k y and values of 0 6 0 9 mm yr for the last 120 k y indicating a uniform rate of faulting since the middle pleistocene crustal seismicity and the mesoseismic areas of historical large events 6 5 m 7 1 which occurred in the calabrian arc are located within a narrow belt along the hanging walls of the quaternary normal fault segments this suggests that the normal faults which dissect the inner side of the calabrian arc may be seismically active

paleoseismologic investigation of the fault rupture of the 14 april 1928 chirpan earthquake m 6 8 southern bulgaria 1 seventy five years after the destructive chirpan earthquake of 14 april 1928 we conducted a paleoseismologic study of the causative fault combining a review of contemporary literature geomorphology geophysical prospecting and trenching we reidentified the fault scarp in the field and mapped it over a distance of 12 5 km geophysical profiles and boreholes demonstrate that chirpan scarp is the surface expression of a normal fault that was active throughout the pleistocene and holocene in 2002 we excavated a paleoseismologic trench to study the faulting history a narrow fault zone separates plio pleistocene alluvial sand in the footwall from holocene alluvial and colluvial silt in the hanging wall the 1928 earthquake is recorded by 0 45 m vertical offset of the topsoil in accordance with contemporary descriptions we identified three colluvial wedge like units in the hanging wall sediments next to the fault evidencing at least three surface rupturing paleoearthquakes since the atlantic their timing could only be loosely constrained using pollen the penultimate event had an offset of 0 40 0 45 m and occurred after circa 2600 calibrated years before present cal years b p event 3 displaced a subboreal semiarid calcic soil 0 55 0 70 m between circa 5750 and 2600 cal years b p the fourth event had a minimal offset of 0 50 0 70 m and occurred between circa 8900 cal years b p and 4900 b c when the region was first settled we obtain a holocene fault slip rate of 0 22 0 12 mm yr and an average recurrence interval of 2350 643 years for earthquakes comparable to or larger than the 1928 event

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

forearc extension and slow rollback of the calabrian arc from gps measurements 1 here we describe the horizontal velocities of continuous gps stations in the calabrian arc ca and surrounding regions the appropriate reference frame to evaluate the crustal motion of the ca is considered by assessing the internal deformation and the relative motion of the crustal blocks in the foreland of the apennines ionian maghrebides subduction system we propose that the motion of ca relative to the subducting ionian lower plate is most properly assessed by minimizing the gps velocities in apulia in this reference frame the significant 2 mm yr southeastward motion of the stations on the ionian flank of the ca shows that the arc is still moving towards the trench in agreement with the observations of active shortening in the ioanian wedge this southeastward migration is associated to 1 4 0 3 mm yr e w extension of the forearc in northern calabria comparable with the seismic strain averaged in the last 500 years the limited subaerial exposure decreases the resolution on locking of the subduction interface but the distribution and direction of crustal extension along the ca impose important constraints on geodynamic interpretations of the area

marine palaeoseismology from very high resolution seismic imaging the gondola fault zone adriatic foreland we present a marine palaeoseismology analysis of a dense network of very high resolution seismic profiles along the gondola fault zone gfz a right lateral e w striking active fault system in the adriatic foreland this case study aims to show how time and space variations in the activity of a dominantly right lateral fault system can be assessed using the vertical component of slip the gfz has been investigated for a length of 50 km it includes two parallel subvertical fault sets and two main anticlines the late middle pleistocene to holocene vertical component of displacement along the fault is bell shaped suggesting that in the long term the fault zone acts as a single kinematically coherent structure slip rates are 0 0 18 mm a 1 and vary temporally on individual segments this variability is consistent with a model in which individual fault segments rupture independently during earthquakes with magnitudes up to 6 4 and 1 3 1 8 ka recurrence intervals

late quaternary tectonics of the vallo di diano basin southern apennines italy italian ministry of university and research project firb research and development of new technologies for protection and defence of territory from natural risks w p c3 crustal imaging in italy

thin shell modeling of neotectonics in the azores gibraltar region we applied the thin shell neotectonic modeling method to study the neotectonics of the africa eurasia plate boundary in the azores gibraltar region the plate boundary consists of a simple fault system running from azores to the gorringe bank where it branches along the betics and rift tell thrust fronts major faults in west iberia and nw africa have also been incorporated results are compared with seismic strain rates fault slip rates and stress orientations the best estimate for the fault friction coefficient is 0 1 0 15 meaning that the plate boundary is only about 1 4 as strong as the adjacent lithosphere the largest fault slip rates 1 5 mm yr are obtained along the gloria fault strike slip and the betic transpressive and rif tell compressive thrust systems whereas tectonic activity in the atlas region is comparable to that obtained along the plate boundary the fault slip rates in the west iberia fault systems are one order of magnitude less