stress directions in eastern north america determined to 4 5 km from borehole elongation measurements stress directions have been determined to depths of 4 5 km in eastern north america from borehole elongation measured by dipmeter calipers in 47 wells the average maximum horizontal stress directions are eastern canada n54 e 7 appalachian basin n58 e 8 and the illinois basin n89 w 5 stress directions determined for the illinois and appalachian basins are in agreement with published interpretations from hydraulic fractures and earthquake fault plane solutions new results from eastern canada and the appalachian basin show that stress directions are everywhere consistent with the midcontinent stress province these data suggest that the maximum horizontal stress does not rotate from the ene midcontinent trend to nw near the atlantic coast a directional analysis of hydraulic fractures petal centerline fractures and natural fractures from the appalachian basin shows that borehole elongation is systematically aligned perpendicular to the directions of hydraulic fractures centerline fractures and northeast striking natural fractures but is not systematically aligned with northwest striking natural fractures these observations indicate that borehole elongations provide reliable stress orientations

the puglia uplift se italy an anomaly in the foreland of the apenninic subduction due to buckling of a thick continental lithosphere the apenninic foreland shows two distinct structural signatures comparing the central adriatic sea and the puglia region during the pliocene pleistocene the central adriatic underwent high subsidence rates due to the eastward rollback of the hinge of the west dipping apenninic subduction the puglia region and the bradanic foredeep are located southward along strike in the same foreland but in contrast with the central adriatic after pliocene early pleistocene subsidence they underwent uplift since the middle pleistocene the geometry and the kinematics of the frontal accretionary wedge and related foreland changed from that moment on between the two areas at the front of the central northern apennines off scraping and subsidence continued whereas the foredeep and foreland of the southern apennines were buckled those differences are interpreted as being due to the larger subduction hinge rollback rate since middle pleistocene of the central adriatic lithosphere 70 km thick with respect to the thicker puglia 110 km the different thicknesses of the continental crust and lithosphere were inherited from the mesozoic rifting that disrupted the adriatic plate the different thicknesses appear to have controlled the variable degree of flexure of the lithosphere and its asthenospheric penetration rate the tremiti e w alignment is the right lateral lithospheric transfer zone of those different tectonic regimes the consequent different dip of the subduction in the two sections steeper west of puglia could also explain the lower elevation of the southern apennines compared to their central northern sector

regional uplift and local tectonic deformation recorded by the quaternary marine terraces on the ionian coast of northern calabria southern italy abstract the setting of a flight of marine terraces along a 65 km long section of the ionian coast of northern calabria is the result of the interaction between interglacial sea levels regional uplift and local fault related elevation changes seven terraces with corresponding palaeoshoreline angles at elevations ranging from 12 m to 420 m were recognised by aerial photo interpretation and field surveying the terraces were correlated to the oxygen isotope stages 1 5a 5c 5e 7 9 15 which correspond to the 7 81 102 124 215 330 and 600 ka highstands of the palaeosea level curve the 600 ka long regional ascent of the terraces took place at an average uplift rate of 0 67 mm yr this value slightly but progressively increases southward along the coastline the elevation of the strandlines is related to the activity of tectonic structures three cases were analysed allowing us 1 to recognise the height anomalies of the terraces on the sibari plain as the result of cumulated coseismic deformation caused by the normal castrovillari fault and on this basis calculate a minimum slip rate and a mean recurrence time for a single event of deformation 2 to exclude the presence of significant vertical deformations and consequently activity on the easternmost section of the normal pollino fault and 3 to hypothesise the presence of an hitherto unknown active fault responsible for the strong vertical displacements of the flight of terraces near the river avena finally we find the ratio of the rate of regional uplift to the average rates of local tectonic deformation to be 2 to 3 1

the recent crustal stress field in central europe trajectories and finite element modeling the recent crustal stress field of central europe and especially of the adjoining areas to the east is presented in terms of the directions of maximum horizontal stress shmax the analysis is based on fault plane solutions in situ stress measurements geologic fault slip determinations and repeated precise geodetic triangulations a bending of the direction of shmax from the well known nw se direction in the western part of the study area to directions of ne sw to e w in the eastern part is shown first results on the recent crustal stress field of the study area were presented by grunthal and stromeyer 1986 who substantiated this tendency of bending in the central and eastern parts of the study area by few observations only therefore one aim of this paper was to compile observations on the areas with few data points generally these additional data confirm the previously established pattern in some areas especially in the pannonian basin the stress features became more complicated compared with those solely based on a few data points the second part of the paper presents steady state elastic finite element model calculations to provide some possible explanations of the observed stress orientations as a result of plate driving forces simulation of the north atlantic seafloor spreading and the northward directed motion of the african plate by appropriate boundary loads produces a pattern of shmax directions for the western part of the eurasian plate which is compatible with the broad scale observed stress directions subregional anomalies such as the fanlike stress pattern perpendicular to the arc of the western alps or the radial directions around the pannonian basin can be explained only when additional stress producing features are introduced overmodulating the regional field rigorous introduction of physically constrained model parameters for all these features was not feasible to date therefore the preliminary empirical model calculations presented in this paper are attempts to discuss which features have the most influence on the stress field they are in a regional scale the north atlantic seafloor spreading the northward motion of the african and the arabian plate and obviously subregionally increased stiffness of the apulian promontary as well as of the bohemian massif

crustal motion along the calabro peloritano arc as imaged by twelve years of measurements on a dense gps network abstract in this work we show the results of 12 years of continuous and survey mode gps measurements carried out along the western part of the calabro peloritano arc from 1996 until the more recent acquisitions in 2008 the results highlight that a nw se oriented 0 15 strain yr extension across the messina strait and the aeolian tindari letojanni fault system is active moreover a n s compressive strain rate 0 65 strain yr is acting across vulcano and lipari islands coupled with an extensional strain rate of 0 15 strain yr in the e w direction finally taking into account the observed horizontal velocity field an analytical inversion was performed to obtain a reliable model of deformation of the investigated area the main results are consistent both with focal mechanism solutions and the current structural setting of the investigated area

understanding tectonic stress in the oil patch the world stress map project knowledge of the present day tectonic stress is essential for numerous applications in petroleum exploration and production and in civil and mining engineering such as improving the stability of boreholes and tunnels and enhancing petroleum production through natural or induced fractures the world stress map wsm project is a collaborative project between academia industry and government that is building a comprehensive global database of present day stress information to better understand the state and sources of contemporary tectonic stress in the lithosphere figure 1

focal mechanism inversion in the giudicarie lessini seismotectonic region southern alps italy insights on tectonic stress and strain abstract a set of 41 focal mechanisms 1989 2006 from p wave first polarities is computed from relocated seismic events in the giudicarie lessini region southern alps estimated hypocentral depths vary from 3 1 to 20 8 km for duration magnitudes md in the range 2 7 5 1 stress and strain inversions are performed for two seismotectonic zones namely g giudicarie and l lessini this subdivision is supported by geological evidence seismicity distribution and focal mechanism types the available number of data 16 in g 22 in l does not make possible any further subdivisions seismotectonic zones g and l are undergoing different kinematic regimes thrust with strike slip component in g and strike slip in l principal stress and strain axes in each sub region show similar orientations the direction of maximum horizontal compressive stress is roughly perpendicular to the thrust fronts along the giudicarie belt in zone g and compatible with right lateral strike slip reactivation of the faults belonging to the schio vicenza system in zone l on the whole kinematic regimes and horizontal stress orientations show a good fit with other stress data from focal mechanisms and breakouts and with geodetic strain rate axes

neogene patterns of relative plate motion for africa europe some implications for recent central mediterranean tectonics a detailed relative motion picture for the neogene africa europe plate kinematics is presented the kinematic reconstruction was carried out using the finite difference solution between the rotation parameters determined for anomalies 7 to 2 in the africa north america europe plate motion circuit the analysis shows a motion of africa with respect to europe which is nne directed during late oligocene to burdigalian times becoming nnw trending from the langhian to the early tortonian from upper tortonian times onward the motion changes to a clear north west directed convergence major late neogene tectonic features of the central mediterranean region can to a large extent be explained within the context of the reconstructed major plate motions late tortonian to recent africa europe slip vectors are compatible with a variety of geological phenomenoa such as north west directed subduction beneath calabria south east translation of calabria and extension in the tyrrhenian sea north west trending slip vectors from thrust earthquakes between gibraltar and sicily and dextral strike slip across the north african margin

european mediterranean regional centroid moment tensors 1997 2000 the mediterranean region is seismically very active and undergoing rapid deformation earthquakes as strong as m 6 are present but relatively rare on the other hand moderate magnitude seismicity 4 5 m 5 5 is widespread and often damaging an improved knowedge of moderate magnitude earthquakes can contribute significantly to a better understanding of active tectonics in the region harvard centroid moment tensors cmt today represent the most widely used reference for reliable source mechanisms but modelling seismic sources with the cmt technique for earthquakes with magnitude less than m 5 5 5 is quite difficult since 1997 we are using an extension of the standard cmt algorithm to compute regional centroid moment tensors rcmt for moderate magnitude earthquakes mw as low as 4 0 analyzing intermediate period surface waves from regional and teleseismic seismograms we routinely apply the algorithm to european mediterranean seismicity to produce a catalog of seismic moment tensors for events with magnitude between 4 5 and 5 5 which generally are not included in the harvard cmt catalog in this paper we show the results for earthquakes that occurred between 1997 and 2000 consisting of 252 solutions and we discuss the characteristics of the catalog and the areas where these new data are most relevant

kinematics and dynamics of the late quaternary rift flank deformation in the hyblean plateau se sicily abstract the southernmost branch of the siculo calabrian rift zone scrz in se sicily is flanked by an actively uplifting 31 km wide and 40 km long rectangular shaped crustal block siracusa domain sd whose late quaternary tectonic evolution has been controlled by the active nw verging thrusting along its northwestern margin accompanied by an extension on the opposite side within the mobile block a local extensional stress field has produced two n140 oriented late quaternary collapsed basins which opened roughly perpendicular to the direction of stretching along the scrz some tectonic peculiarities of the sd such as the occurrence of shortening in absence of a crustal back stop the coexistence of local extensional and contractional stress field and the primary role played by fluids in the deformational processes suggest a possible connection between the shallower crustal dynamics with a deep seated mantle intrusion beneath the region as it is commonly documented to occur along the rift zones where the rift flank volcanism develops similar dynamics and kinematics have been in fact described in the adjacent areas of the western flank of scrz which are affected by volcanism e g eolian islands and mt etna the results of our study in the hyblean region give thus the opportunity to detail on the mode and the mechanics of faulting that can be significant to interpret the seismicity and active deformation in the adjacent volcanic areas of sicily

stress field of italy mean stress orientation at different depths and wave length of the stress pattern we have studied the stress pattern of italy using a dataset with 590 data records from the world stress map database release 2008 and 106 new data records to test the hypothesis the mean orientation of maximum horizontal stress sh is different at different depth sections for this we split the dataset into a shallow 0 6 km and a deep 6 40 km depth section for the data analysis we used a new statistical tool that calculates the mean sh orientation on a 0 2 grid the tool takes into account the distance to each grid point number and quality of the data records within the search radius and the radial distribution the result is a smoothed italian stress map that displays both the mean sh orientation and the wave length of the stress pattern the stress pattern does not vary in depth except for two areas sardinia and southern apulia therefore stress data from different depths can be used to estimate the mean sh orientation and the wave length of the stress pattern in italy furthermore the smoothed italian stress map reveals that most of italy has short wave length stress patterns 150 km this indicates that the stress field is not controlled by first order stress sources of plate tectonics i e the convergence of africa with respect to eurasia but that second order stress sources such as topography density strength contrasts and major faults systems are of great importance in four regions western part of the alps northern tuscany northern adriatic sea calabria and eastern part of sicily the wave length is 100 km high values of the circular variance of the mean sh orientation observed here are driven by third order local stress sources such as basins or local neotectonic structures

recent tectonic evolution and present stress in the northern apennines italy the present day stress field and its recent tectonic evolution in the northern apennines are reconstructed from borehole breakout analysis and focal mechanisms of crustal earthquakes and through the comparison with paleostress data we have considered 86 wells for breakout analysis with depths down to 6 7 km 125 fault plane solutions of crustal earthquakes with m 5 that occurred between 1988 and 1995 in the northern and central apennines and data of stronger earthquakes m 6 reported in other studies the tyrrhenian coastal region and the apenninic belt are characterized by shmin direction mainly trending ne sw with predominantly normal fault plane solutions along the outer front of the belt and the adriatic offshore shmin is oriented nw se and focal solutions are thrust or strike slip with maximum compression around ne sw conversely south of 43 n breakouts evidence an orthogonal direction of horizontal compression nw se following the southern apennine trend where a widespread ne sw extension was recognized by previous investigations comparing these results to the recent tectonic evolution inferred from structural geology we argue that the extension compression pair characteristic of the post tortonian evolution of the mountain belt has been migrating in time from late miocene to present only in the northern sector of the arc whereas the southern sector underwent a generalized extension at least since middle pleistocene the striking correspondence between the active compression front and the region with evidence of a remnant subducted slab suggests that the migrating extension compression pair has been controlled by progressive retreat of the slab

present day stress field modelling of southern italy constrained by stress and gps data abstract the present day tectonic setting of the italian peninsula is very complex and involves competing geodynamic processes in this context southern peninsular italy is characterised by extension along the apenninic belt and in the tyrrhenian margin and by transpression in the apulia gargano region the extension is well defined by means of geological seismological and contemporary stress data for the latter only few data are available in the apulia gargano region leaving the state of stress in that area unresolved here we develop a finite element model of the southern italian region in order to predict the contemporary stress field our model predictions are constrained by model independent observations of the orientation of maximum horizontal stress s hmax the tectonic regime and the horizontal velocities derived from gps observations we performed a blind test with 31 newly acquired s h max orientations in the southern apennines these new data come from the analysis of orehole breakouts performed in 46 deep oil exploration wells ranging in depth from 1300 to 5500 m the model results agree with the stress data that define a prevailing nw se s h max orientation along the apenninic belt and foredeep and thus are capable to predict the stress field where no stress information is available we first analyse how much model predictions based on older data deviate from present day stress data and then recalibrate the models based on our new stress data giving insight into the resolution of both models and data in the studied region which is affected by low deformation rates we find that geodetic data alone cannot resolve such low levels of deformation due to the high relative measurement errors we conclude that both gps and stress data are required to constrain model results

subduction and the depth of convection in the mediterranean mantle 1 we tie together geological data paleotectonic reconstruction plate motion and tomographic analysis to unravel the history of subduction and back arc extension of the eastern and central mediterranean in these two regions extensional processes started contemporaneously around 30 myr ago but with marked differences in the eastern region the aegean basin opened slowly 1 cm yr behind a shallow dipping slab 40 45 the corresponding high velocity anomaly extends inside the upper mantle and can be also followed in the midmantle down to a depth of at least 1500 km its descent into the midmantle initiated most probably during the late cretaceous and the trench moved northeastward following the path of the eurasian plate and under the persistent push of the african plate conversely in the central mediterranean region subduction initiated later and the motion of the subducting slab is confined to the upper mantle causing punctuated and rapid episodes of back arc extension provencal and tyrrhenian basins behind a slab that dips steeply 75 we explore the causes that control how the slab subducted and interacted with the lower more viscous part of the mantle

active stress map of italy we present a new map of the present day stress field in italy obtained from all the available data the map reports 200 horizontal stress directions inferred from 109 borehole breakout data 44 centroid moment tensor solutions 34 other focal mechanisms most of which are from polarity distributions seven stress inversions of microearthquake data two averages of t and p axes of earthquake focal mechanisms in zones of diffuse seismic activity and four fault slip data the integration of breakout data which yield horizontal stress directions with fault plane solutions which reflect the stress regime allows us to obtain an improved map of the present day stress in italy this stress field map can be used for a better comprehension of active tectonic processes for seismic hazard assessment and to foresee the behavior of faults recognized with other methods stress directions obtained from different data although relative to different depth intervals e g 0 7 km for breakouts and 0 20 km for most of the earthquakes and to different tectonic units are consistent since many regions in italy are characterized by an extensional stress regime we report the minimum horizontal stress shmin orientations the map shows that an extensional regime affects most of the apenninic belt conversely a compressional or transpressional regime characterizes the eastern alps the eastern side of the northern apennines and the southern tyrrhenian to northern sicily zone an abrupt change in stress directions marks the transition between northern and southern apennines suggesting that the two arcs are characterized by a different tectonic setting and recent evolution in this paper we report all the data analyzed to date with their geographic coordinates and average stress directions and we describe the main stress provinces in italy in the framework of the tectonic evolution of the region

compaction induced stress variations with depth in an active anticline northern apennines italy 1 it is shown that the stress field can vary with depth even within a homogeneous tectonic setting as documented for the active mirandola fault related fold along the buried front of the northern apennines analyses of borehole breakouts and other well data integrated with seismological information and field evidence show that extension perpendicular to the fold axis above approximately 1200 m changes to a strike slip stress field and finally to compression near the main detachment at depth similar along depth strain variations recognized in non active anticlines are usually explained by invoking tangential longitudinal strain folding i e stretching above and shortening below a neutral surface or gravitational instabilities however in this study we propose that differential compaction may play a significant and generally overlooked role with the aid of numerical modeling it is shown that where fold limbs are onlapped by highly compactable deposits as in the mirandola area differential compaction induces stretching at shallow 1 2 km depths the amount of stretching is a function of the shape of the fold and of the thickness of the syn tectonic sediments we conclude that in the mirandola case study the stress variations observed with depth are the result of a combination of a regional compression at depth and local tension driven by differential compaction of growth strata on the limbs of the anticline with respect to its crest

a 125 kyr long geological record of seismic source repeatability the messina straits southern italy and the 1908 earthquake ms7 2 the occurrence of characteristic earthquakes along segments of major active belts has been described as early as the beginning of the century the large 1908 messina straits blind normal faulting earthquake provides an opportunity to investigate the repetition of characteristic earthquakes and the persistency of the main features of the fault zone over a time scale in the order of 100 kyr we have compared seismological and geodetic descriptions of the 1908 rupture process with long term crustal deformation recorded at different stratigraphic levels by marine terraces marine sedimentary units and landscape features the wealth of elevated coastal features in and around a region affected by large normal faulting earthquakes indicates that coseismic strain is superimposed on much faster uplift on a regional scale we investigated in detail the pattern of deformation of the 125 kyr old lowest emergent terrace and found that it mimics the pattern of elevation changes observed following the earthquake this suggests 1 that the 1908 earthquake is characteristic 2 that its segment boundaries have been stationary during the past 125 kyr and 3 that even the locations of the regions of largest coseismic release do not change through many seismic cycles based on a comparison between observed heights of the 125 kyr terrace and 1908 displacements we estimated an average repeat time of 1000 yr for a 1908 type earthquake we also investigated the height position age and state of deformation of older terraces and found 1 that uplift of the region started about 1 ma and has since continued rather uniformly at 0 9 1 4 mm yr 1 2 that during this time the straits have narrowed at a rate of 10 20 mm yr 1 and 3 that all the main geomorphic features of the messina straits result from the interaction of fast regional uplift 1908 type coseismic subsidence and global sea level fluctuations

plate boundary forces are not enough second and third order stress patterns highlighted in the world stress map database 1 the world stress map project compiles a global database of contemporary tectonic stress information of the earth s crust early releases of the world stress map project demonstrated the existence of first order plate scale stress fields controlled by plate boundary forces and second order regional stress fields controlled by major intraplate stress sources such as mountain belts and zones of widespread glacial rebound the 2005 release of the world stress map project database provides for some areas high data density that enables us to investigate third order local stress field variations and the forces controlling them such as active faults local inclusions detachment horizons and density contrasts these forces act as major controls on the stress field orientations when the magnitudes of the horizontal stresses are close to isotropic we present and discuss examples for venezuela australia romania brunei western europe and southern italy where a substantial increase of data records demonstrates some of the additional factors controlling regional and local stress patterns

patterns of tectonic stress in sicily from borehole breakout observations and finite element modeling the orientation of in situ tectonic stress was deduced from borehole breakout analysis of 22 wells from onshore sicily the results allow us to distinguish the stress field of different geological units 1 a nearly nnw 148 orientation is detected in the hyblean plateau 2 a nne shmax direction characterizes the gela area to the north within the thrust belt around mount judica the shmax direction swings to ne in the northeastern segment of the foredeep the catania plain the direction of shmax is roughly parallel to the ne trending grabens that mark the northern margin of the hyblean plateau 3 the southwestern segment of the foredeep has no preferential shmax orientation and may act as a transition zone with isotropic horizontal stresses 4 in western sicily a shmax orientation from n s to nw se is observed this fits well the kinematics of the se migrating egadi and adventure thrust belts and the direction of shortening inferred from the modern seismicity of the area a three dimensional finite element modeling including the most important tectonic features was performed modeling results of the stress field indicate that the nnw trending shmax is locally influenced by the variation of crustal thickness and local zones of weakness in addition the pantelleria rift causes a rotation of the regional nw se stress orientation to nne along the northern rim of the rift system including large on shore areas in the adjacent central south sicily

p wave tomography of the mantle under the alpine mediterranean area 1 we study the upper mantle p wave velocity structure below the euro mediterranean area down to 1000 km depth by seismic travel time tomography we invert summary residuals constructed with both regional and teleseismic first arrival data reported by the international seismological centre isc 1964 1995 introducing some alternative strategies in the travel time tomographic approach and a new scheme to correct teleseismic data for global mantle structure our high resolution model pm0 5 is parameterized with three dimensional 3 d linear splines on a grid of nodes with 0 5 spacing in both horizontal directions and 50 km vertical spacing we obtain about 26 root mean square rms reduction of residuals by inversion in addition to roughly 31 reduction after summary rays formation and selection sensitivity analyses are performed through several test inversions to explore the resolution characteristics of the model at different spatial scales the distribution of large scale fast anomalies suggests that two different stages of a convection process presently coexist in very close regions the mantle dynamics of western central europe is dominated by blockage of subducted slabs at the 660 km discontinuity and ponding of seismically fast material in the transition zone contrarily in the eastern mediterranean fast velocity material sinks into the lower mantle suggesting that the flow of the cold downwelling here is not blocked by the 660 km discontinuity on a smaller scale the existence of tears in the subducted slab lithospheric detachment all along both margins of the adriatic plate as proposed by some authors is not supported by our tomographic images

thrust front segmentation induced by differential slab retreat in the apennines italy new seismic reflection data reveal that the south eastward prolongation of the apennine thrust front in the central adriatic sea is most likely located in a more external position with respect to the traditional interpretation in this new interpretation the apennine thrust front shows a segmented geometry in correspondence to the tremiti lithospheric transfer zone the available data suggest that the north eastward flexural retreat of the subducting adriatic lithosphere and the related frontal accretion of the apennine accretionary prism have acted during the last 5 ma and may be considered still lively in both the po plain and in the central adriatic domain north of the tremiti lineament by analysing the tectonic evolution of the apulo adriatic areas it may be argued that the differential slab retreat between the central and southern sectors of the subducting adriatic plate has been able to induce the segmentation of the apennine thrust front

widespread extension in the core of the western alps revealed by earthquake analysis the western alps are an active collision belt whose current stress field is inhomogeneous muller et al 1992 we report new seismological data which significantly improve our knowledge of this stress field about 1600 earthquakes which occurred in the western alps during the last 10 years were precisely located and 79 new focal solutions were computed the analysis of this database shows that widespread extension affects all the internal zones of the belt to better constrain the associated stress regime six stress tensors were computed using the gephart and forsyth 1984 method they show that the current tectonics of the western alps are contrasted with close variation in the stress regime transpression to the front of the belt contrasting with extension in the core of the belt the extensional direction is radial to the arcuate geometry of the belt and bounded outboard by the former thrust of the internal zones onto the external zone suggesting extensional reactivation of this inherited crustal discontinuity such widespread extension within the inner part of an actually ongoing collision belt cannot be explained by simple collision related tectonics we propose that intrabelt buoyancy forces such as those produced by a slab retreat or slab break off interfere with the boundary forces driven by the ongoing europe africa convergence

the italian cmt dataset from 1977 to the present abstract the ingv harvard european mediterranean regional centroid moment tensor rcmt catalog collects solutions routinely computed since 1997 for earthquakes with moderate magnitude 4 5 m 5 5 in the mediterranean region the database represents an extension to smaller magnitudes of the harvard global cmt catalog based on analysis of seismograms recorded at regional distance and modeling of intermediate period surface waves the catalog includes about 600 events 200 of which in the italian region this study extends the catalog back in time for the italian region as long as made possible by available digital data i e since 1977 with the same analysis and inversion method used for current seismicity as a result we present here 65 new moment tensors for years between 1977 and 1997 these solutions represent 45 of the total number of events analyzed the existing seismograms being often too scarce to allow a stable solution the new dataset includes events in many seismic zones where moderate seismicity had previously been scarcely documented e g the po plain the central to southern apennines and the adriatic sea the complete dataset including previously determined rcmts and cmts represents the seismic deformation in the italian area during the last 25 years

the southern tyrrhenian subduction zone deep geometry magmatism and plio pleistocene evolution abstract we report on a high resolution vp vp vs and qp model of the southern tyrrhenian subduction zone obtained by the inversion of p and s wave arrival times and t values from intraslab seismicity the arcuate shape of the southern apennines calabrian arc sicilian maghrebides is perfectly mirrored by two rather continuous low and high vp bands lying beneath the belt system at ca 25 and 100 km respectively between 100 and 300 km two independent high vp slabs lie beneath the neapolitan region and the southern tyrrhenian sea separated by unperturbed mantle we suggest that the ca 150 km wide slab window beneath the southern apennines opened after a tear occurring within a composite subduction system formed by the apulian continental lithosphere and the ionian oceanic slab the abrupt slab rupture induced ultrafast southeastward retreat of the ionian slab and the 19 cm yr spreading of the back arc oceanic marsili basin between ca 2 1 and 1 6 ma ago the 25 km low vp zone beneath the arc denotes continental upper crustal rocks below the chain its striking continuity requires a unique orogenic wedge at 25 km depth below the southern apennines the calabrian arc and the sicilian maghrebides the alternative explanation would imply the ubiquitous occurrence of autochthonous lower plate rocks at 25 km depth i e a puzzling autochthonous continental calabria the ionian slab beneath calabria shows high vp high qp and low vp vs anomalies typical of old oceanic lithosphere intermediate depth seismicity is concentrated within its thin oceanic crust suggesting the occurrence of vigorous metamorphism the slab dehydration promotes the melting of the overlying mantle as testified by high vp vs and low qp anomalies between the slab and the aeolian magmatic arc

new gps constraints on the africa eurasia plate boundary zone in southern italy 1 southern italy is a key area for understanding the tectonic processes in the africa eurasia collision zone we analyze new gps measurements carried out between 1994 and 2001 the results are presented in terms of time series trajectories and velocities of crustal motion as well as a geodetic strain rate field while central italy corsica sardinia and the tyrrhenian sea move like the eurasian plate the overall motion of the sicily rift zone region matches african plate motion unexpected are the north northwest directed motions of northeastern sicily and the eolian islands most striking on the deformation field are a north south oriented compression along the northern sicilian coast compression between apulia and northwestern greece as well as extension in the sicily rift zone and the interior of sicily

stress and strain tensors based on focal mechanisms in the seismotectonic framework of the friuli venezia giulia region northeastern italy the principal axes of stress and strain are inferred for the seismotectonic zones of the friuli venezia giulia region which forms the eastern part of the european southern alps this region corresponds to a polyphase deformational belt formed during the meso and neoalpine compressions from the eocene to plio quaternary several distinct seismotectonic zones are recognized by comparing seismological and tectonic characteristics inference of the stress and strain tensors is based on 243 fault plane solutions corresponding to earthquakes occurring between 1984 and 2001 magnitude range 2 1 5 6 the analysis reveals two main regional stress patterns a strike slip regime active in the eastern and northwestern parts of the area under study and dominant thrusting processes in the central and western zones the orientation of the maximum principal stress varies from north northwest south southeast to north northeast south southwest the stress magnitude ratio of the calculated stress tensors varies from 0 4 to 0 7 the orientation of the maximum shortening axis is generally north northwest south southeast changing to north northeast south southwest in the southeastern part of the region for most seismotectonic domains the inferred strain pattern is quite concordant with the surface tectonics the orientations of the principal axes of stress and strain are in most cases similar the complex regional tectonic structure consisting of two indented tectonic wedges appears to control the patterns of horizontal stress and strain

transmission of basal variability to a glacier surface 1 transmission of basal variability to a glacier surface is investigated using analytical models for a linearly viscous medium the three dimensional transient response of the surface to both bedrock undulations and spatial variations in basal slipperiness for perturbations of arbitrary wavelengths is determined using perturbation methods both information transfer toward the surface and lateral transmission of horizontal stresses are strongly affected by the slip ratio that is the ratio of basal sliding to deformational velocity for any mean bedrock slope and above a minimum value of slip ratio the amplitude transfer of bedrock undulations toward the surface has a local maximum at undulation span corresponding to about 3 8 times the mean ice thickness the transmission of basal variability to a glacier surface increases quite significantly with increasing slip ratio this explains why the surfaces of fast flowing ice streams are more undulating than the slower moving bordering areas at slip ratios higher than about 100 the flow of glaciers and ice sheets becomes nonlocal in the sense that surface velocities and buildup and propagation of surface undulations cannot be calculated accurately on the basis of local thickness and slope using linearized long wave theories at these slip ratios instead of the more accurate arbitrary wavelength theory gives estimates of decay times that are an order of magnitude too small and phase velocities several times too large the problem of the propagation and decay of small amplitude surface undulations on glaciers in three dimensions is solved small amplitude surface waves on glaciers are strongly diffusive and dispersive redistribution of mass on ice sheets and glaciers is a diffusion process and it is misleading albeit not mathematically incorrect to describe the reaction of glaciers to surface perturbations in terms of a wave propagation

seismic strain and seismogenic stress regimes in the crust of the southern tyrrhenian region abstract an investigation has been performed to identify and characterize the seismic deformation zones active over the last decades in the region of italy that has experienced the strongest seismicity during the last centuries the study is based on the estimate of hypocenter locations fault plane solutions seismogenic stress and seismic strain tensor orientations carried out using the entire dataset of the national and local seismic networks and the recently improved three dimensional 3d crustal velocity model of the study area a series of simulation tests have been performed to evaluate the significance of the earthquake space distribution obtained and whether it was influenced by network geometry problems related to the sea and the lack of ocean bottom seismometers in the sectors where hypocentral location was synthetically proved to be reliable space distributions of earthquakes located with epicenter and focal depth errors less than 3 and 4 km respectively have been compared with local geology in order to identify seismogenic faults the dataset of 32 fault plane solutions estimated with fault parameter errors less than 20 has been used to investigate space variations of seismogenic stress and seismic strain orientations over the study area stress was found to be uniform in the messina strait and southern calabria where inversion of the available set of 11 fault plane solutions showed clear evidence of an extensional regime the different orientations of the minimum compressive stress and strain found in this sector together with the information available on local geology and tectonics lead us to propose that the seismicity occurring over the last decades in the messina strait and southern calabria was not in general produced at the main faults but at minor faults activated by the main tectonic stress field acting in the area to the west in the sector including western etna the nebrodi chain and the western aeolian islands analysis of the available set of 16 fault plane solutions revealed a certain degree of stress heterogeneity with an apparent prevalence of north south compression this east to west change of stress strain regimes is evaluated in the light of current hypotheses regarding the geodynamics of the study region

active fragmentation of adria the north african promontory central mediterranean orogen global positioning system gps velocities indicate that adria no longer behaves as a rigid tectonic indenter into southern europe and is divided into northwestern and southeastern velocity domains differential motions are recognized in a velocity field determined from the peri tyrrhenian geodetic array ptga and international gps service igs sites in the circum tyrrhenian region of the central mediterranean and published gps velocities from the eastern adriatic coast in a fixed eurasian reference frame ptga and igs site velocities in sicily and southern italy are as much as 10 mm yr in a northward direction similar to gps velocities along the eastern coast of the adriatic sea in contrast velocities in northern italy are small or statistically insignificant and similar to velocities in sardinia and corsica outboard of western adria the tectonic boundary dividing adria is seismically active and passes around the southern and eastern margins of the tyrrhenian basin crosses central italy extends into the adriatic sea and follows the western margin of the dinaride tectonic belt north to the gulf of venice the eastern margin of adria is approximately located and follows the axis of the central dinaric alps southeast to the hellenic arc southeastern adria has a velocity related to northward motion of africa whereas northwestern adria has negligible differential motion in the eurasian frame and now is part of the alpine collage of southern europe

incipient extension along the active convergent margin of nubia in sicily italy cefalu etna seismic zone 1 recent geodetic data are compatible with nne ssw tectonic extension at a rate of 5 mm yr in sicily southern italy within a broader region of net active compression along the nubian plate margin northern africa the structures that accommodate such extensional regime and its cause are still unknown from field structural surveys and seismological analyses the geometry kinematics structural architecture and seismic potential of an extensional seismic zone linking cefalu and mount etna in central eastern sicily are defined the zone includes high angle wnw striking normal and right lateral strike slip faults and subordinate north and nne striking strike slip faults either right or left lateral the occurrence of small discontinuous faults and the absence of related depressions and sedimentary basins suggest that the extensional regime is still in an incipient stage the ongoing seismic activity possibly reactivates preexisting faults instrumentally and historically recorded earthquakes are lower than about 6 in magnitude and destructive events are historically unknown since at least 1300 a d this apparent upper bound of earthquake magnitudes is consistent with the maximum magnitude values estimated from the length of the longest mapped faults and sources of seismic swarms which all together suggest a value between 6 and 6 5 as the maximum expected magnitude that can be proposed at the present stage of investigation for earthquakes in the study area lateral extension on preexisting faults and upwelling of melt mantle material beneath mount etna are considered viable processes to explain at least in part the active extensional tectonics along the cefalu etna seismic zone strike slip seismic faulting beneath mount etna may be part of a previously proposed diffuse transfer zone affecting northeastern sicily and including the tindari fault

different foreland basins in italy examples from the central and southern adriatic sea abstract the central adriatic basin cab and the southern adriatic basin sab are foreland or foredeep basins relative to the non coeval apenninic and dinaric hellenic orogenic systems and currently characterized by different physiographies these are separated by a major forebulge of the adriatic lithosphere running throughout the adriatic region from istria to the gargano promontory the clastic basin filling of the cab is mostly plio pleistocene whereas it is upper oligocene pleistocene in the sab stratigraphy reveals that the cab has experienced an overfilling regime throughout the plio pleistocene whereas the sab has been probably continuously underfilled during the same time span in the cab the foreland plate dips westward at an average angle of 5 6 whereas in the sab the basement dips to the east at an angle of 1 2 this discrepancy is congruent with the already noticed distinction between east and west dipping subduction systems and possibly has geodynamical implications in the cab the non homogeneous distribution of thrust sheets suggests strike slip tectonic movements along roughly ne trending lineaments that occurred up to the middle late pliocene on the western part of the sab the overall structural assemblage recalls the fabric typical to strike slip regimes and includesboth extensional and contractional structures it is proposed that the messinian salinity crisis and relative eustatic lowstand affected the subsequent tectono sedimentary evolution of the cab in terms of subsidence rate and depositional style one still tentative hypothesis is that water and sediment removal in the basin lasted for a sufficient time span to promote viscoelastic relaxation temporary migration of the forebulge towards the thrust belt and downwarping of the foreland plate

spatial variations of seismogenic stress orientations in sicily south italy abstract seismogenic stress orientations are estimated in the lithosphere of sicily by inversion of 131 local earthquake focal mechanisms fms selected from the literature an average misfit f 14 5 between stress tensor and fms indicates that the entire set of earthquakes is generated by a highly heterogeneous stress field detailed analysis of stress tensors and related earthquake misfits obtained for tens of subsets based on spatial separation of data allowed us to identify two main stress domains in the study region i a compressional domain including etna western sicily and the southern tyrrhenian sea offshore sicily where the 1 orientation roughly changes from nw se in the etna area and western sicily to nne ssw at the northeastern edge of the domain eolian islands and ii an extensional domain in northeastern sicily between the eolian islands and etna where 3 is oriented analogously to previously estimated in the easterly confining extensional area of the messina straits general agreement is found between this stress pattern and the gps crustal displacement vectors reported in the most recent literature for the study region moreover stress inversion enables us to locate the extensional domain more accurately than the presently available gps data finally the stress orientations estimated in the southern and western sectors of the study area etna and western sicily on and offshore match well with the displacement fields predicted for sicily by large scale models of plate motion conversely a mismatch is observed in the northeastern sector eolian islands and northeastern sicily we suggest that the joint action of africa eurasia convergence and ionian subduction trench retreat rollback of the subducting slab may explain the stress pattern detected in sicily in the present study work for computation of a finite element regional geodynamic model based on geophysical and geological data collected over the last few years has recently started with the purpose of quantitatively checking this hypothesis

statistical trends in the intraplate stress field the world stress map wsm database contains thousands of intraplate stress indicators with the potential to provide important constraint for arguments about the relationship between tectonic stresses and both the kinematics and dynamics of plate motion previous studies which relied almost exclusively on visual inspection of the data established the existence of broad regions of uniform maximum horizontal compressive stress orientation shmax and stress regimes on a regional scale in the present study we present a statistical analysis of the wsm stress indicators with the aim of quantifying trends in both the shmax orientations and stress regimes the analysis was carried out within 5 5 bins which provide a resolution of several hundred kilometers only the 4537 high quality wsm indicators with rating of a to c were used in the analysis we present results for two types of analysis on the information contained within the bins first we evaluate the spatial distribution of the average stress regime normal strike slip or thrust second we apply the rayleigh test a standard statistical method in the analysis of directional data to the distribution of shmax orientations to test the null hypothesis that the orientations are random an important aspect of our study is the quantification of the conclusions drawn from visual inspection of the world stress map our results indicate that broad regions of uniform shmax orientations exist in most continental regions at high confidence levels 90 and 95 and are less robust in the slowest moving continental plates we also quantify the predominance of strike slip and compressional stress regimes in continental regions importantly our analysis provides information about trends in the shmax orientations in regions where large amounts of scatter in the directional data prevented conclusions being drawn from visual inspection of the data for example in western north america and continental australia furthermore we find a strong correlation between average shmax orientations and both the ridge push torque and the absolute plate velocity azimuths our observation that a greater number of shmax orientations correlate with the ridge push torque directions is further evidence that the intraplate stress field is strongly influenced by the ridge push force

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

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

two and three dimensional numerical simulations of the stress field at the thrust front of the northern apennines italy 1 two and three dimensional mechanical models simulating the seismic cycle along thrust faults are devoted to the active front of the northern apennines buried under the plio pleistocene sediments of the eastern po plain the models aim at understanding two peculiar characters of the stress field in the region 1 analyses of borehole breakouts and other well data integrated with seismological information and field evidence show along depth variations from extensional to strike slip to compressional for increasing depth of the stress style along the active mirandola anticline and 2 seismic and borehole breakout data suggest strong lateral rotations of the stress axes along the frontal and lateral ramp portions of the mirandola thrust fault modeling results allowed us to understand that the mechanical decoupling along faults strongly affects the stress distribution in their vicinity under the form of strong rotations of the principal stress axes as a consequence the slip either fast or slow along active blind thrust faults could drive to local stress fields very different from that associated with regional tectonics this could explain together with other processes such as differential compaction the along depth variation of the stress field observed in the mirandola region and the strong lateral rotations of the principal stress axes observed along the lateral ramp of the mirandola thrust fault finally the seismic activity along one of the thrust fault ramps along the apennines front should not interfere with the state of stress along adjacent ramps

the adriatic region an independent microplate within the africa eurasia collision zone 1 we use gps measurements and block modeling to investigate the present day deformation of the adriatic region whose kinematics within the nubia eurasia plate boundary zone is not well constrained and remains controversial block modeling allows us to compute rigid plate angular velocities while accounting for elastic strain accumulation along block bounding faults results suggest that the adriatic is a microplate adria and that the southern boundary with the nubia plate and the aegean domain may be located along the apulia escarpment and the kefallinia fault geodetic data alone cannot discriminate between a single block ap or a two blocks gdap description of adria but the gdap model predicts boundary slip rates that are in better agreement with observations from previous studies

evidence for a post 3 16 ma change in nubia eurasia north america plate motions we combine updated gps velocities from the nubian nu eurasian eu and north american na plates with 500 new 3 16 myr average seafloor spreading rates and nine transform fault azimuths from the northern atlantic and arctic basin seafloor spreading centers to estimate and test for changes in the relative motion between these plates the numerous new seafloor spreading rates and gps velocities improve our ability to detect recent changes in the relative motions of these plates the angular velocity vector that best fits the eu na gps velocities lies significantly north of the 3 ma average pole in accord with previously published geologic evidence that the eu na pole has migrated northward since v3 ma although we also find evidence for a significant post 3 ma change in nu na motion it is less compelling because the nubian plate gps velocity field is sparse and nu na seafloor spreading rates appear to have remained steady within the 1 mm yr 31 uncertainties if we systematically decrease the seafloor spreading rates to correct for outward displacement of seafloor spreading magnetic lineations the nu eu pole derived from gps site velocities lies more than 30 angular degrees south of the tightly constrained 3 ma average estimate and predicts significantly slower and more oblique present day nu eu convergence in the mediterranean both models for nu eu motion pass a key test for their accuracy namely they correctly predict strike slip motion along the well mapped gloria fault east of the azores the change to more oblique nu eu motion may reflect increasing difficulty in maintaining margin normal convergence within this continent continent collision zone 8 2003 published by elsevier b v

the arc of the western alps in the light of geophysical data on deep crustal structure recently two international deep seismic campaigns in the western and central alps etude continentale et oceanique par reflexion et refraction sismique progetto strategico crosta profonda ecors crop roure et al 1996b and national research program 20 nrp 20 pfiffner et al 1997 have been completed here we present a synoptic interpretation of the wealth of geophysical data about deep crustal structure of the alps collected during the past 40 years including the two above mentioned geophysical projects the tectonic reinterpretation of the ecors crop high resolution seismic transect is based on an evaluation of the deep crustal structure by integrating new and literature data on surface geology combined with previously published interpretations regarding the central alps schmid et al 1996 this study reveals substantial differences in geometry and kinematics between transects across the western and central alps respectively at depth the transition between the central and western alps is marked by the western limits of an adriatic lower crustal wedge shaped structure and the northeastern limits of a similar structure made of european lower crustal material at the surface it coincides with a corridor of dextral strike slip along the tonale and simplon lines in addition the thickness of the seismogenic zone shows a remarkable variation from over 40 km beneath the penninic realm of the western alps to less than 20 km in the central alps the formation of the western alpine arc was initiated during convergence and collision before 35 myr ago when the adriatic micro plate moving northward with respect to the european foreland caused sinistral transpression in the western alps while the central and eastern alps underwent head on convergence and collision during the post collisional stage i e after 35 myr ago the arcuate shape of the western alps was accentuated by wnw directed movement and anticlockwise rotation of the adriatic microplate decoupled from the central and eastern alps along the tonale simplon dextral shear zone this led to wedging of lower crustal slices both in the western alps and in the central alps the new tectonic interpretation of the ecors crop transect allows a kinematic model to be established for crustal shortening in the western alps during the past 35 myr the ivrea mantle plays the role of a backstop in our tectonic model we distinguish three episodes of post collisional crustal shortening along the ecors crop transect from 35 to 30 ma the brianconnais basement was back thrusted over the gran paradiso units leading to 30 km of crustal shortening first episode in the early miocene movements concentrated mainly along the penninic frontal thrust and resulted in about 60 km shortening second episode post 12 ma shortening within the external massifs is associated with folding in the jura mountains when the crust was shortened by an additional 30 km third episode

an overview of rock stress measurement methods this paper presents an overview of methods that have been used to estimate the state of stress in rock masses with the emphasis on methods applicable to hard rocks and scandinavia rock stress is a difficult quantity to estimate because the rock stress measuring techniques consist of perturbing the rock measuring displacements or hydraulic parameters and converting the measured quantities into rock stresses there are two main types of method those that disturb the in situ rock conditions i e by inducing strains deformations or crack opening pressures and those that are based on observation of rock behaviour without any major influence from the measuring method the most common methods are briefly described including their application areas and limiting factors

neogene and quaternary rollback evolution of the tyrrhenian sea the apennines and the sicilian maghrebides reconstruction of the evolution of the tyrrhenian sea shows that the major stage of rifting associated with the opening of this basin began at similar to10 ma it involved two episodes of back arc extension which were induced by the rollback of a west dipping subducting slab the first period of extension 10 6 ma was prominent in the northern tyrrhenian sea and in the western part of the southern tyrrhenian sea the second period of extension mainly affected the southern tyrrhenian sea began in the latest messinian 6 5 ma and has been accompanied by subduction rollback at rates of 60 100 km myr 1 slab reconstruction combined with paleomagnetic and paleogeographic constraints indicates that in the central apennines the latest messinian 6 5 ma arrival of a carbonate platform at the subduction zone impeded subduction and initiated a slab tear and major strike slip faults these processes resulted in the formation of a narrow subducting slab beneath the ionian sea that has undergone faster subduction rollback and induced extreme rates of back arc extension

present state of tectonic stress of the friuli area eastern southern alps stress orientations are determined for the friuli area from focal mechanisms using the inversion technique of gephart and forsyth 1984 the data consist of 244 fault plane solutions selected for the period 1988 1995 where the data coverage was poor this period was extended to 1978 1996 local magnitude ranges from 2 0 to 4 3 and the depths extend from 4 to 16 km the friuli area is subdivided into five seismotectonic zones on the basis of tectonic characteristics seismic activity and focal mechanisms and for each zone a stress tensor is determined the results show that the active tectonic stress in the friuli area is heterogeneous and conditioned by the complex structural pattern which is characterized by two indented tectonic wedges the western and central parts of the area are mainly affected by a compressional state of stress while in the eastern part a strike slip state of stress prevails the orientation of the principal stresses varies from the western to the eastern part of the area and differences are also noticeable with depth in the central part of the friuli area the maximum compressional stress is n s trending at shallow depths 10 km changing to nw se at deeper levels the maximum compressional stress is nw se oriented in the western part while in the eastern part it is n s oriented

subcrustal earthquakes in the northern apennines italy evidence for a still active subduction previously unreported subcrustal earthquakes have been located up to 90 km depth beneath the northern apennines italy these earthquakes occur beneath a zone of abundant upper crustal seismicity mostly confined to the upper 20 km of the crust although there are relatively few well located subcrustal earthquakes there appears to be a general southwestward deepening of the hypocenters from the adriatic to the tyrrhenian sea consistent with other geophysical data which suggest that the adriatic lithosphere is presently subducting beneath the northern apennines

present day kinematics of the plate boundary zone between africa and europe from the azores to the aegean anticlockwise rotation of africa relative to europe around an euler pole in the eastern atlantic causes plate convergence in the central mediterranean towards n20 w at rate considered a priori to be 5 10 mm yr 1 however previous summaries of the present day deformation sense in the central mediterranean are inconsistent with observations in southern italy recent investigations of italy and adjacent parts of north africa enable local deformation sense observed to be reconciled with sense predicted from relative plate motions suggested angular velocity of the african plate relative to europe is 0 07 myr 1 around a pole near 21 n 21 w this predicts 2 6 mm yr 1 maximum extension rate towards n64 e near the azores consistent with the minimum local accretion of new oceanic crust in the past few millions of years and 4 3 mm yr 1 plate convergence towards n20 w in the central mediterranean at 13 e further east the northern margin of the african plate can be regarded as the gargano seismic zone in the central adriatic sea the northern adriatic sea is a microplate rotating anticlockwise relative to europe at 0 3 myr 1 around a pole in northwestern italy causing northeastward shortening in yugoslavia and up to 4 mm yr 1 extension in central and northern italy the african plate is deforming internally in tunisia and northern libya extending obliquely in direction e10 s at rate up to 5 5 mm yr 1 the resultant velocity relative to europe in the ionian and southern adriatic seas 5 mm yr 1 towards n50 e explains the observed relative velocity across southern italy kinematic consistency requires present day shortening rate east of calabria associated with subduction on the tyrrhenian sea benioff zone and tyrrhenian sea extension rate to be both zero or equal to within 1 mm yr 1

regional patterns of tectonic stress in europe nearly 1500 stress orientation determinations are now available for europe the data come from earthquake focal mechanisms overcoring measurements well bore breakouts hydraulic fracturing measurements and young fault slip studies and sample the stress field from the surface to seismogenic depths three distinct regional patterns of maximum compressive horizontal stress shmax orientation can be defined from these data a consistent nw to nnw shmax stress orientation in western europe a wnw ese shmax orientation in scandinavia similar to western europe but with a larger variability of shmax orientations and a consistent e w shmax orientation and n s extension in the aegean sea and western anatolia the different stress fields can be attributed to plate driving forces acting on the boundaries of the eurasian plate locally modified by lithospheric properties in different regions on average the orientation of maximum stress in western europe is subparallel to the direction of relative plate motion between africa and europe and is rotated 17 clockwise from the direction of absolute plate motion the uniformly oriented stress field in western europe coincides with thin to medium lithospheric thickness approximately 50 90 km and high heat flow values 80 m w m2 in western europe a predominance of strike slip focal mechanisms implies that the intermediate principal stress is vertical the more irregular horizontal stress orientations in scandinavia coincide with thick continental lithosphere 110 170 km and low heat flow 50 m w m2 the cold thick lithosphere in this region may result in lower mean stresses associated with far field tectonic forces and allow the stress field to be more easily perturbed by local effects such as deglaciation flexure and topography the stress field of the aegean sea and western anatolia is consistent with n s extension in a back arc setting behind the hellenic trench subduction zone the stress field is influenced in places by regional geologic structures e g in the western alps where shmax directions show a slight tendency toward a radial stress pattern not all major geologic structures however appear to affect the shmax orientation e g in the vicinity of the rhine rift system horizontal stress orientations are continuous

morphometric analysis and amino acid geochronology of uplifted shorelines in a tectonic region near reggio calambria south italy the tectonic coastline of the calabrian peninsula provides an opportunity to study the morphology and history of elevated marine shorelines near capo dell armi eleven shorelines are preserved between sea level and 256 m with some correlation difficulties posed by the dissection of the area by intermittent streams we are able to correlate several of the shorelines across the entire study area with the support of correlations provided by amino acid geochronology we have identified four shorelines dating from the last interglacial period isotope stage 5 the oldest two both contain the strombus bubonius fauna and are of indistinguishable early last interglacial ages stage 5e aminozone e ca 125 ka the highest terrace vii is associated with a shoreline at 157 m and the lower with a shoreline around 125 105 m a s l of the two younger stage 5 without strombus bubonius the higher v lies at about 90 100 m and produces amino acid ratios slightly younger than but statistically indistinguishable from those of aminozone e however the youngest last interglacial shoreline deposits iv have produced amino acid ratios correlated to late stage 5 5a elsewhere in the mediterranean basin amino acid and geomorphic data have shown that uplift varies the study area from 0 85 to 1 03 m ka and suggeststhat constant uplift along any one traverse is unlikely