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

effects of material property variations on slip estimates for subduction interface slow slip events we investigate the influence of elastic heterogeneity on geodetic inversions of slow slip events by inverting for slip distributions of four events along the hikurangi margin new zealand we generate green s functions using a finite element code in conjunction with a new zealand wide seismic velocity model to assign elastic properties we find that these heterogeneous models typically require 20 less slip than homogeneous models in cases where the slip is deep or there is reasonable geodetic coverage above the slipping region in cases where the slip is shallow and mostly offshore and there is little geodetic coverage directly above the slipping region the heterogeneous models can predict significantly larger amounts of slip 42 in our study these changes in the predicted amounts of slip have important implications for quantifying slip budgets accommodated by slow slip at subduction zones worldwide

coseismic slip distribution of the 2015 mw7 8 gorkha nepal earthquake from joint inversion of gps and insar data for slip within a 3 d heterogeneous domain

3d geological reconstruction of the m vettore seismogenic fault system central apennines italy cross cutting relationship with the m sibillini thrust abstract the 2016 2017 amatrice norcia seismic sequence was triggered by the reactivation of a complex nnw sse trending wsw dipping normal fault system cross cutting the umbria marche fold and thrust belt near m vettore this fault system produced clear and impressive co seismic ruptures on normal faults in the hangingwall of the m sibillini thrust whereas ruptures in the footwall were observed but less clear as a result a strong controversy exists in the literature about the geometry of the seismogenic faults their relationships with pre existing thrusts and the location of normal faulting rupture tips in this work we present a 3d geological model of the m vettore area located between the castelluccio basin and the outcrop of the m sibillini thrust where the most evident co seismic ruptures have been observed the model shows the relationship between the ruptured normal faults and the m sibillini thrust and was constructed using a grid of 14 geological cross sections parallel and orthogonal to the main structural elements i e normal faults and thrusts down to a depth of 3 km the model was built using reference structural surfaces such as the top of the early cretaceous maiolica fm the m sibillini thrust and the main seismogenic normal faults belonging to the m vettore fault system the 3d model has allowed us to calculate the vertical cumulative throw distribution for the m vettore normal faults the cumulative geological throw of ca 1300 m across the normal faults in the proximity of the m sibillini thrust indicates that the seismogenic fault system continues into the footwall of the thrust displacing it in the sub surface the results of this study provide important constraints on the cross cutting relationships between active normal and pre existing compressional structures in seismically active areas contributing to a better definition of the faults segmentation and the related seismic hazard

an audiofrequency magnetotelluric traverse across the mana pools basin northern zimbabwe summary audiofrequency magnetotelluric soundings in the frequency range 0 016 128 hz have been conducted to investigate the structure of the mana pools basin in northern zimbabwe a karoo sedimentary basin in the zambezi valley data from nine tensorial soundings along a 40 km n s traverse from the river zambezi to the zimbabwe craton and a further sounding on the escarpment have been processed giving the sounding curves required for preliminary modelling studies a variety of l d inversion algorithms have subsequently been applied to these processed data sets to yield interpretive models an approximate 2 d geoelectrical section has been derived by collating the 1 d models a marked and rapid contrast in subsurface resistivity distribution between the escarpment and the basin is apparent within the basin the results show the presence of a top sequence of variable thickness up to 10 km overlying a more resistive 0 1 s m 1 unit that may represent the geoelectrical basement these top sequences which have tentatively been interpreted as sedimentary formations with different stratigraphic units consist of highly conducting 0 3 s m 1 to 1 s m 1 materials overlain by a slightly more resistive typically 0 2 s m 1 unit in some cases with another good conductor adjacent to the surface the data also suggest a rapid thinning of the top sequences close to the escarpment in contrast to the more gradual decrease of the sediments in previous geophysical models for the area on the escarpment the resistivity is higher at all depths the mana pools basin thus appears to be a continuation of the good conductor running from namibia into western zimbabwe identified by de beer 1982a and provides a link to another beneath the lower zambezi basin to the east of mana pools discovered magnetotellurically by losecke knodel muller 1988 comparisons between the geoelectrical model and other available results for the region are presented

geodetic imaging reservoir monitoring using satellite interferometry summary fluid fluxes within subsurface reservoirs give rise to surface displacements particularly over periods of a year or more observations of such deformation provide a powerful tool for mapping fluid migration within the earth providing new insights into reservoir dynamics in this paper we use interferometric synthetic aperture radar insar range changes to infer subsurface fluid volume strain at the coso geothermal field furthermore we conduct a complete model assessment using an iterative approach to compute model parameter resolution and covariance matrices the method is a generalization of a lanczos based technique which allows us to include fairly general regularization such as roughness penalties we find that we can resolve quite detailed lateral variations in volume strain both within the reservoir depth range 0 4 2 5 km and below the geothermal production zone 2 5 5 0 km the fractional volume change in all three layers of the model exceeds the estimated model parameter uncertainty by a factor of two or more in the reservoir depth interval 0 4 2 5 km the predominant volume change is associated with northerly and westerly oriented faults and their intersections however below the geothermal production zone proper the depth range 2 5 5 0 km there is the suggestion that both north and northeast trending faults may act as conduits for fluid flow

finite fault inversion of dinsar coseismic displacement of the 2009 l aquila earthquake central italy 1 we define the geometric and kinematic characteristics of the fault activated during the mw 6 3 6 april 2009 l aquila earthquake from the modeling of envisat and cosmo skymed the first ever x band interferogram inverted for a coseismic dislocation study dinsar interferograms our best fit solution for the main shock is represented by a normal fault 16 km long and 12 km wide with a small right lateral component dipping 47 sw with a maximum slip of 90 cm although the seismic dislocation probably ended at 1 km depth the updip projection of the fault plane corresponds to the northern segment of the mapped paganica s demetrio fault where alignment of surface breaks was observed in the field the absence of this fault in existing seismic source catalogues suggests that an improved approach involving detailed surface and subsurface geological and geophysical investigations is needed for a better assessment of the seismic hazard at the local scale

the use of invariant impedances in magnetotelluric interpretation summary it is suggested that the use of invariant impedances may avoid the possible erroneous interpretation of magnetotelluric data which can occur when 1 d modelling of the e polarization response is carried out the possibility of erroneous interpretation occurs in the vicinity of near surface 3 d conductivity anomalies the suggestion is tested on a numerical 3 d model first published by wannamaker et al 1984 a correct interpretation of the conductivity structure is obtained however over a shallow highly conducting anomaly it is not possible to resolve deep structure

kinematics of the western africa eurasia plate boundary from focal mechanisms and gps data summary the western mediterranean displays a complex pattern of crustal deformation distributed along tectonically active belts developed in the framework of slow oblique plate convergence we used earthquake and global positioning system gps data to study the present day kinematics and tectonics of the africa eurasia plate boundary in this region crustal seismicity and focal mechanisms analysed in terms of seismic moment release and seismic deformation outline the geometry of major seismic belts and characterize their tectonics and kinematics continuous gps data have been analysed to determine euler vectors for the nubian and eurasian plates and to provide the global frame for a new mediterranean gps velocity field obtained by merging continuous and campaign observations collected in the 1991 2005 time span gps velocities and displacements predicted by the nubia eurasia rotation pole provide estimates of the deformation accommodated across the tectonically active belts the rather simple deformation occurring in the atlantic region characterized by extension about perpendicular to the middle atlantic and terceira ridges and right lateral motion along the gloria transform fault turns into a complex pattern of deformation occurring along broader seismic belts where continental lithosphere is involved our analysis reveals a more complex fragmentation of the plate boundary than previously proposed the roughly e w trending mainly compressive segments i e southwestern iberia northern algeria and southern tyrrhenian where plate convergence is largely accomodated across rather localized deformation zones and partially transferred northward to the adjacent domains i e the algero balearic and tyrrhenian basins are interrupted by regions of more distributed deformation i e the rif alboran betics tunisia libya and eastern sicily or limited seismicity i e the strait of sicily which are characterized by less homogeneous tectonics regimes mainly transcurrent to extensional in correspondence of the observed breaks tectonic structures with different orientation interfere and we find belts with only limited deformation i e the high and middle atlas the tunisian atlas and the offshore tunisia libya belt that extends from the plate boundary into the nubian plate along pre existing tectonic lineaments our analysis suggest that the sicilian pelagian domain is moving independently from nubia according to the presence of a right lateral and extensional decoupling zone corresponding to the tunisia libya and strait of sicily deformation zone despite the space variability of active tectonic regimes plate convergence still governs most of the seismotectonic and kinematic setting up to the central aeolian region in general local complexities derive from pre existing structural features inherited from the tectonic evolution of the mediterranean region on the contrary along calabria and the apennines the contribution of the subducted ionian oceanic lithosphere and the occurrence of microplates i e adria appear to substantially modify both tectonics and kinematics finally gps data across the gibraltar arc and the tyrrhenian calabria domain support the hypothesis that slab rollback in these regions is mostly slowed down or stopped

crustal velocity structure in italy from analysis of regional seismic waveforms abstract in this article we use regional seismic waveforms recorded by the recently installed istituto nazionale di geofisica e vulcanologia ingv national network and the mediterranean very broadband seismographic network mednet stations to develop 1d crustal velocity models for the italian peninsula about 55 000 p wave and 35 000 s wave arrival times from 4727 events are used to derive average seismic parameters in the crust and uppermost mantle we define four regions according to geological constraints and recent travel time tomography results based on the average seismic parameters we combine broadband seismic waveforms and travel times of regional phases to model crustal structures for the four regions by applying the genetic algorithm our results indicate smooth velocity gradients with a depth beneath the apennines and a deep moho beneath the central alps green s functions from the regionalized 1d velocity models are used to determine source depths and focal mechanisms for 37 events with a magnitude larger than 3 5 by a grid search technique our results show that normal and strike slip faulting source mechanisms dominate the apenninic belt and that most thrust faulting events occur in the adriatic sea and the outer margin of the northern apennines

coseismic ruptures of the 24 august 2016 mw 6 0 amatrice earthquake central italy on 24 august 2016 a mw 6 0 normal faulting earthquake struck central italy causing about 300 fatalities and heavy damage a geological survey collected the coseismic effects observed at the surface in order to evaluate two competing hypotheses about their nature surface faulting versus gravitational deformation we find that the most significant geological effect is a 5 2 km long alignment of ground ruptures along the mt vettore fault system these ruptures are independent from lithology topography morphology and change in slope and exhibit an average dip slip displacement of 13 cm geometry kinematics and dimensional properties of this zone of deformation strongly lead us to favor the primary surface faulting hypothesis that fits well the predicted estimates from experimental scaling law relationships our study provides relevant hints for surface faulting in extensional domains contributing to implement the worldwide database of the moderate earthquakes

finite element model predictions of static deformation from dislocation sources in a subduction zone sensitivities to homogeneous isotropic poisson solid and half space assumptions 1 dislocation models can simulate static deformation caused by slip along a fault these models usually take the form of a dislocation embedded in a homogeneous isotropic poisson solid half space hipshs however the widely accepted hipshs assumptions poorly approximate subduction zone systems of converging oceanic and continental crust this study uses three dimensional finite element models fems that allow for any combination including none of the hipshs assumptions to compute synthetic green s functions for displacement using the1995 mw 8 0 jalisco colima mexico subduction zone earthquake and associated measurements from a nearby gps array as an example fem generated synthetic green s functions are combined with standard linear inverse methods to estimate dislocation distributions along the subduction interface loading a forward hipshs model with dislocation distributions estimated from fems that sequentially relax the hipshs assumptions yields the sensitivity of predicted displacements to each of the hipshs assumptions for the subduction zone models tested and the specific field situation considered sensitivities to the individual poisson solid isotropy and homogeneity assumptions can be substantially greater than gps measurement uncertainties forward modeling quantifies stress coupling between the mw 8 0 earthquake and a nearby mw 6 3 earthquake that occurred 63 days later coulomb stress changes predicted from static hipshs models cannot account for the 63 day lag time between events alternatively an fem that includes a poroelastic oceanic crust which allows for postseismic pore fluid pressure recovery can account for the lag time the pore fluid pressure recovery rate puts an upper limit of 10 17 m2 on the bulk permeability of the oceanic crust

multidisciplinary inferences on a newly recognized active east dipping extensional system in central italy we use a multidisciplinary approach to gather preliminary evidence for a quaternary east dipping extensional detachment in central italy this structure crops out in the sabini eastern simbruini ses and would be hidden at mid crustal depths beneath the l aquila 2009 mw6 3 epicentral area the ses geometry is reconstructed through geological mapping structural analysis and seismic line interpretation the geometry of the mid crustal segment referred to as the ocre segment os is interpreted through seismological analyses of the largest aftershock mw5 4 of the l aquila 2009 sequence the kinematic compatibility between the ses and the os under a common sw ne tensional field is tested through stress inversion of both geological and seismological data the reliability of os activation is tested through slip tendency analysis like other italian cases the ses and the os are preliminarily interpreted as expressions at different depths of the same unknown east dipping extensional detachment characterized by a ramp flat ramp geometry

complexity of the rupture process during the 2009 l aquila italy earthquake summary in this study we investigate the rupture history of the 2009 april 6 mw 6 1 l aquila normal faulting earthquake by using a non linear inversion of strong motion gps and dinsar data both the separate and joint inversion solutions reveal a complex rupture process and a heterogeneous slip distribution slip is concentrated in two main asperities a smaller shallow patch of slip located updip from the hypocentre and a second deeper and larger asperity located southeastwards along strike direction the key feature of the source process emerging from our inverted models concerns the rupture history which is characterized by two distinct stages the first stage begins with rupture nucleation and with updip propagation at relatively high 4 0 km s 1 but still subshear rupture velocity the second stage starts nearly 2 0 2 5 s after nucleation and it is characterized by the along strike rupture propagation the largest and deeper asperity fails during this stage of the rupture process the rupture velocity is larger in the updip than in the along strike direction the updip and along strike rupture propagation are separated in time and associated with a mode ii and a mode iii crack respectively the comparison between the source models inferred in this study with the poisson ratio anomalies in the crustal volume containing the fault plane allows the interpretation of the delay in along strike rupture propagation in terms of a structural control of the rupture history our results show that the l aquila earthquake featured a very complex rupture with strong spatial and temporal heterogeneities suggesting a strong frictional and or structural control of the rupture process

complex deformation at shallow depth during the 30 october 2016 m w 6 5 norcia earthquake interference between tectonic and gravity processes the relation between slip at the near surface and at depth during earthquakes is still not fully resolved at the moment this deficiency leads to large uncertainties in the evaluation of the magnitude of past earthquakes based on surface observations which is the only accessible evidence for such events a better knowledge of the way slip distributes over distinct rupture strands within the first few kilometers from the surface would contribute greatly to reduce these uncertainties the 30 october 2016 mw6 5 norcia earthquake has been captured by a variety of geodetic techniques which provide access to the slip distribution both at depth and at the ground surface with an unprecedented level of detail for a normal faulting earthquake we first present coseismic surface offset measurements from correlation of optical satellite images of submetric resolution which are compared to field observations made shortly after the earthquake based on a joint inversion of optical data together with insar and gps data we then propose a rupture model that explains the observations both at far field and near field scales finally we explore different rupture geometries at shallow depth in an attempt to better explain the near field deformation i e within the first hundreds of meters around the fault observed at the surface despite the fact that the solution is not unique several lines of evidence suggest that gravity processes could be locally involved which interfere with the dominant tectonic processes

effect of crustal layering upon dislocation modeling slip distribution at depth on a fault may be inferred from the deformation observed on the surface in inverting the surface deformation data to obtain the slip distribution the earth is generally approximated by an elastic half space slip distributions inferred from a half space model may contain artifacts including zones of reversed slip due solely to effects of layering in the real earth this effect is demonstrated for a vertical strike slip fault in an earth consisting of an elastic layer overlying an elastic half space slip on the fault is taken to be independent of the along strike coordinate i e antiplane strain is assumed for a given slip distribution in this model the slip distribution on a similar fault in an elastic half space is found that produces the identical surface deformation comparison of the two slip distributions reveals structure introduced into the half space equivalent slip profile by crustal layering the comparisons suggest that low resolution inversion schemes e g single screw dislocation models are not drastically affected by earth structure but attempts at detailed inversion are likely to produce profiles contaminated by artifacts of earth structure

impacts of topographic relief and crustal heterogeneity on coseismic deformation and inversions for fault geometry and slip a case study of the 2015 gorkha earthquake in the central himalayan arc

homogeneous vs heterogeneous subduction zone models coseismic and postseismic deformation a finite element model fem incorporating geologic properties characteristic of a subduction zone is compared with fems approximating homogeneous elastic half spaces hehs s to investigate the effect of heterogeneity on coseismic and postseismic deformation predictions for the 1995 colima jalisco m w 8 0 earthquake the fems are used to compute a coefficient matrix relating displacements at observation points due to unit dislocations of contact node pairs on the fault surface the green s function responses are used to solve the inverse problem of estimating dislocation distributions from coseismic gps displacements predictions from the fem with heterogeneous material properties loaded with either of the hehs dislocation distributions significantly overestimate coseismic displacements postseismic deformation predictions are also sensitive to the coseismic dislocation distribution which drives poroelastic and viscoelastic relaxation fem generated green s functions which allow for spatial variations in material properties are thus preferable to those that assume a simple hehs because the latter leads to dislocation distributions unsuitable for predicting the postseismic response

the september 26 1997 colfiorito italy earthquakes modeled coseismic surface displacement from sar interferometry and gps the largest events of the 1997 umbria marche seismic sequence were the two september 26 earthquakes of mw 5 7 00 33 gmt and mw 6 0 09 40 gmt which caused severe damage and ground cracks in a wide area around the epicenters we created an ers sar differential interferogram where nine fringes are visible in and around the colfiorito basin corresponding to 25 cm of coseismic surface displacement gps data show a maximum horizontal displacement of 14 1 8 cm and a maximum subsidence of 24 3 cm we used these geodetic data and the seismological parameters to estimate geometry and slip distribution on the fault planes modeled fault depths and maximum slip amplitudes are 6 5 km and 47 cm for the first event and 7 km and 72 cm for the second one in good agreement with those derived from the seismological data

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

slip heterogeneity and directivity of the ml 6 0 2016 amatrice earthquake estimated with rapid finite fault inversion on 24 august 2016 a magnitude ml 6 0 occurred in the central apennines italy between amatrice and norcia causing nearly 300 fatalities the main shock ruptured a nnw sse striking wsw dipping normal fault we invert waveforms from 26 three component strong motion accelerometers filtered between 0 02 and 0 5 hz within 45 km from the fault the inferred slip distribution is heterogeneous and characterized by two shallow slip patches updip and nw from the hypocenter respectively the rupture history shows bilateral propagation and a relatively high rupture velocity 3 1 km s the imaged rupture history produced evident directivity effects both n nw and se of the hypocenter explaining near source peak ground motions fault dimensions and peak slip values are large for a moderate magnitude earthquake the retrieved rupture model fits the recorded ground velocities up to 1 hz corroborating the effects of rupture directivity and slip heterogeneity on ground shaking and damage pattern

geodetic model of the 2016 central italy earthquake sequence inferred from insar and gps data we investigate a large geodetic data set of interferometric synthetic aperture radar insar and gps measurements to determine the source parameters for the three main shocks of the 2016 central italy earthquake sequence on 24 august and 26 and 30 october mw 6 1 5 9 and 6 5 respectively our preferred model is consistent with the activation of four main coseismic asperities belonging to the sw dipping normal fault system associated with the mount gorzano mount vettore mount bove alignment additional slip equivalent to a mw 6 1 6 2 earthquake on a secondary 1 ne dipping antithetic fault and or 2 on a wnw dipping low angle fault in the hanging wall of the main system is required to better reproduce the complex deformation pattern associated with the greatest seismic event the mw 6 5 earthquake the recognition of ancillary faults involved in the sequence suggests a complex interaction in the activated crustal volume between the main normal faults and the secondary structures and a partitioning of strain release

accumulation of fossil fuels and metallic minerals in active and ancient rift lakes a study of active and ancient rift systems around the world suggests that accumulations of fossil fuels and metallic minerals are related to the interactions of processes that form rift valleys with those that take place in and around rift lakes the deposition of the precursors of petroleum gas oil shale coal phosphate barite cu pb zn sulfides and uranium begins with erosion of uplifted areas and the consequent input of abundant nutrients and solute loads into swamps and tectonic lakes hot springs and volcanism add other nutrients and solutes the resulting high biological productivity creates oxidized reduced interfaces and anoxic and h2s rich bottom waters which preserves metal bearing organic tissues and horizons in the depositional phases the fine grained lake deposits are in contact with coarse grained beach delta river talus and alluvial fan deposits earthquake induced turbidites also are common coarse grained deposits of rift lakes postdepositional processes in rifts include high heat flow and a resulting concentration of the organic and metallic components that were dispersed throughout the lakebeds postdepositional faulting brings organic and metal rich sourcebeds in contact with coarse grained host and reservoir rocks a suite of potentially economic deposits is therefore a characteristic of rift valleys

coseismic slip vectors of 24 august and 30 october 2016 earthquakes in central italy oblique slip and regional kinematic implications after 24 august and 30 october 2016 central italy earthquakes mw 6 0 and 6 5 respectively photogrammetry and geodetic survey were performed at various sites along a 6 km long portion of the rupturing monte vettore fault system providing very high resolution georeferenced 3 d point clouds and imagery of the 24 august rupture and a data set of bedrock fault scarp before after the 30 october earthquake the maximum coseismic displacement for both events occurs near scoglio dell aquila with an average normal dip slip of 22 4 and 184 6 cm respectively coseismic slip vectors and meter scale corrugation axis are oriented n280 10 on the n140 striking main vettore fault involving oblique normal slip with a right lateral component and n205 10 on n170 fault strands implying oblique normal slip with a left lateral component we quantify the near field coseismic displacements of the monte vettore fault for the 30 october event the footwall has been translated horizontally by 42 2 cm toward the ene and uplifted by 11 2 cm the hangingwall has moved horizontally by 26 2 cm toward the nw in a direction parallel to the fault plane and subsided by 116 2 cm the fault geometry and our determined surface coseismic slip vectors are mechanically compatible with a 3 n65 15 this stress regime is consistent with the 30 october 2016 focal mechanism and the relative motion between the adriatic microplate and the tyrrhenian coastal region the 30 october surface rupture results from seismic slip at depth and thus has a tectonic origin

nonlinear estimation of geometric parameters in fems of volcano deformation integrating tomography models and geodetic data for okmok volcano alaska 1 the internal structure loading processes and effective boundary conditions of a volcano control the deformation observed at the earth s surface using finite element models fems we simulate the response due to a pressurized magma chamber embedded in a domain having a distribution of elastic material properties we present the pinned mesh perturbation method pmp to automate the mesh generation process in response to perturbations of the position of a simulated magma chamber within an fem domain using insar observed deformation for the 1997 eruption of okmok volcano alaska as an example we combine pmp with nested monte carlo methods to estimate a set of linear and nonlinear parameters that characterize the depressurization and location of the magma chamber beneath okmok s caldera the three dimensional fems used in the pmp method simulate the distribution of material properties of tomography models and account for the irregular geometry of the topography and bathymetry the estimated depth of an assumed spherical magma chamber is 3527 54 55 m below sea level and is sensitive to the distribution of material properties this depth is consistent with lithostatic pressure constraints and very long period tremor observations the fit of this fem to the insar data is a significant improvement at the 95 confidence level compared to the fit of a corresponding fem having homogeneous material properties the methods presented here allow us to construct deformation models that integrate tomography models with geodetic observations in an effort to achieve a deeper understanding of active volcanoes

seismological geological and geophysical constraints for the gualdo tadino fault umbria marche apennines central italy abstract the april 3 1998 mw 5 1 gualdo tadino earthquake central italy was the last significant event in the 6 month long umbria marche seismic crisis this event and its aftershocks occurred in an area where active faulting produces no striking geological and geomorphological effects in this study we investigated the ruptured fault using detailed seismological data and a re processed and re interpreted seismic reflection profile aftershock location and focal mechanisms were used to constrain the geometry and kinematics of the ruptured fault and a comparison was made with the subsurface image provided by the seismic profile we found that the 1998 gualdo tadino earthquake occurred on a wsw dipping normal fault with a length of about 8 km and a relatively gentle dip 30 40 confined between 3 5 and 7 km in depth kinematics of the mainshock and aftershocks revealed a ne trending extension in agreement with the regional stress field active in the northern apennines belt the mw 5 1 earthquake originated above the top of the basement and ruptured within the sedimentary cover which consists of an evaporites carbonates multilayer we hypothesised that the active fault does not reach the surface blind normal fault

very detailed seismic pattern and migration inferred from the april 2010 pietralunga northern italian apennines micro earthquake sequence abstract we propose a very detailed picture of seismicity that occurred in the proximity of the alto tiberina fault atf northern italian apennines a low angle normal fault by presenting the pattern and evolution of a seismic sequence on the hanging wall of the atf in the first months of 2010 that was characterized by about 1000 events with m l ranging from 0 7 to 3 8 to capture the rupture kinematics of the investigated area a cross correlation technique was initially applied to calculate very accurate time shifts among the events of the sequence and then to relocate them the whole sequence was relocated with the double difference method which includes both absolute travel time measurements and cross correlation differential travel times the new locations confirm that the seismic activity was mainly arranged along a nw se oriented structure that ranged in depth from 4 km to 6 km with dipping towards ne at an angle of ca 65 in comparison with geological data the position of the seismic sequence is compatible with the evaporite triassic layer the main nodal planes are consistent with the spatial evolution of the aftershocks and with the tensional state of stress in the area an analysis of waveform similarity was performed at a reference station by merging the capability of the cross correlation technique and the bridging algorithm the detected mutiplets allow us to emphasize the anisotropic spatial and temporal migrations of the seismicity that occurred along a 307 n strike direction with an averaged propagation velocity of ca 0 4 km day we explain the highlighted anisotropic behavior of the migration with the hypothesized presence of overpressured fluids and with physical properties of triassic evaporites this suggests the importance of such very detailed relocation of weak and micro seismicity for improvement of our knowledge of fault system geometry and its evolution

coseismic slip distribution for the mw 9 2011 tohoku oki earthquake derived from 3 d fe modeling 1 the coseismic slip distribution of the mw 9 0 2011 tohoku oki earthquake has been estimated by inverting near field onshore and offshore geodetic data using green s function calculated with a 3 d finite element fe model the fe model simulates several geophysical features of the subduction zone that hosted the rupture surface of the event these features include a 3 d geometric configuration and distribution of material properties of the tectonic system a precise geometric configuration of the irregular rupture surface and an irregular free surface according to the topography and bathymetry a model that simulates rupture along the interface between the relatively weak overriding okhotsk plate and stiff subducting slab of the pacific plate requires less slip to produce the observed surface deformation compared to a model having uniform material properties across the rupture interface furthermore the estimated slip of the heterogeneous model is more widely distributed over the shallow portion of the plate boundary whereas the estimated slip of the homogeneous model is more focused updip of the epicenter this demonstrates the sensitivity of inverse analyses of geodetic data for the 2011 tohoku oki earthquake to the simulated domain geometry and configuration of material properties

uncertainties in strong ground motion prediction with finite fault synthetic seismograms an application to the 1984 m 5 7 gubbio central italy earthquake abstract this study investigates the engineering applicability of two conceptually different finite fault simulation techniques we focus our attention on two important aspects first to quantify the capability of the methods to reproduce the observed ground motion parameters peaks and integral quantities second to quantify the dependence of the strong motion parameters on the variability in the large scale kinematic definition of the source i e position of the nucleation point value of the rupture velocity and distribution of the final slip on the fault we applied an approximated simulation technique the deterministic stochastic method and a broadband technique the hybrid integral composite method to model the 1984 m w 5 7 gubbio central italy earthquake at five accelerometric stations we first optimize the position of the nucleation point and the value of the rupture velocity for three different final slip distributions on the fault by minimizing an error function in terms of acceleration response spectra in the frequency band from 1 to 9 hz we found that the best model is given by a rupture propagating at about 2 65 km sec from a hypocenter located approximately at the center of the fault in the second part of the article we calculate more than 2400 scenarios varying the kinematic source parameters at the five sites we compute the residuals distributions for the various strong motion parameters and show that their standard deviations depend on the source parameterization adopted by the two techniques furthermore we show that arias intensity ai and significant duration are characterized by the largest and smallest standard deviation respectively housner intensity is better modeled and less affected by uncertainties in the source kinematic parameters than ai the fact that the uncertainties in the kinematic model affects the variability of different ground motion parameters in different ways has to be taken into account when performing hazard assessment and earthquake engineering studies for future events

co seismic displacements of the 1994 northridge california earthquake the 17 january 1994 northridge california earthquake significantly deformed the earth s crust in the epicentral region displacements of 66 survey stations determined from global positioning system gps observations collected before and after the earthquake show that individual stations were uplifted by up to 417 5 mm and displaced horizontally by up to 216 3 mm using these displacements we estimate parameters of a uniform slip model fault geometry and slip are estimated independent of seismological information using monte carlo optimization techniques that minimize the model residuals the plane that best fits the geodetic data lies 1 to 2 km above the plane indicated by aftershock seismicity modeling for distributed slip on a coplanar yet larger model fault indicates that a high slip patch occurred up dip and northwest of the mainshock hypocenter and that less than 1 m of slip occurred in the uppermost 5 km of the crust this finding is consistent with the lack of clear surface rupture and with the notion that the intersection with the fault that ruptured in 1971 formed the up dip terminus of slip in the northridge earthquake displacements predicted by either of these simple models explain most of the variance in the data within 50 km of the epicenter on average however the scatter of the residuals is twice the data uncertainties and in some areas there is significant systematic misfit to either model the co seismic contributions of aftershocks are insufficient to explain this mismatch indicating that the source geometry is more complicated than a single rectangular plane

bayesian dynamic finite fault inversion 2 application to the 2016 m w 6 2 amatrice italy earthquake in 2016 central italy was struck by a sequence of three normal faulting earthquakes with moment magnitude mw larger than 6 the mw 6 2 amatrice event 24 august was the first one causing building collapse and about 300 casualties the event was recorded by a uniquely dense network of seismic stations here we perform its dynamic source inversion to infer the fault friction parameters and stress conditions that controlled the earthquake rupture we consider a linear slip weakening friction law with spatially variable parameters along the fault the inversion uses a novel bayesian framework developed in our companion paper which combines efficient finite difference dynamic rupture simulations and the parallel tempering monte carlo algorithm to sample the posterior probability density function the main advantage of such formulation is that by subsequent analysis of the posterior samples we can infer stable features of the result and their uncertainty the inversion results in a million of visited models the preferred model ensemble reveals intriguing dynamic features the rupture exhibits a slow and irregular nucleation followed by bilateral rupture propagation through two asperities accelerating toward the heavily damaged city of amatrice the stress drop reaches locally 10 15 mpa with slip weighted mean of 4 4 5 mpa the friction drop ranges from 0 1 to 0 4 the characteristic slip weakening distance is the most heterogeneously distributed dynamic parameter with values of 0 2 0 8 m the radiation efficiency was rather low 0 2 suggesting that approximately 80 of the total available energy was spent in the fracture process while just 20 was radiated by seismic waves

coseismic deformation and triggered landslides of the 2016 mw 6 2 amatrice earthquake in italy the central apennines in italy have had multiple moderate size but damaging shallow earthquakes in this study we optimize the fault geometry and invert for fault slip based on coseismic gps and interferometric synthetic aperture radar insar for the 2016 mw 6 2 amatrice earthquake in italy our results show that nearly all the fault slip occurred between 3 and 6 km depth but extends 20 km along strike there was less than 4 cm static surface displacement at the town amatrice where the most devastating damage occurred landslides triggered by earthquake ground shaking are not uncommon but triggered landslides with submeter movement are challenging to be observed in the field we find evidence of coseismically triggered deep seated landslides northwest and northeast of the epicenter where coseismic peak ground acceleration was estimated 0 5 g by combining ascending and descending insar data we are able to estimate the landslide thickness as at least 100 and 80 m near monte vettore and west of castelluccio respectively the landslide near monte vettore terminates on the preexisting fault monte vettore fault mvef scarp our results imply that the long term fault slip rate of mvef estimated based on paleoseismic studies could potentially have errors due to triggered landslides from nearby earthquake events

slip kinematics and dynamics during and after the 1995 october 9 mw 8 0 colima jalisco earthquake mexico from gps geodetic constraints we use horizontal and vertical crustal displacements derived from gps measurements at 26 sites in western mexico to study the coseismic and post seismic kinematics and dynamics of the 1995 october 9 m w 8 0 colima jalisco earthquake along the middle america trench the measurements bracket the entire landward edge of the approximately 150 km long rupture zone and span a 4 yr period for most sites we solve for the temporal evolution of slip along the subduction interface by inverting gps displacements for the coseismic and four post seismic intervals march 1995 march 1999 subject to the assumption that the crust responds elastically to slip along a shallow dipping curved subduction interface coseismic rupture of up to 5 m was largely focused above depths of 20 km and was limited to a 120 140 km long segment of the subduction zone within one week of the earthquake post seismic slip migrated downdip to depths of 16 35 km where it has since decayed logarithmically we also find evidence for shallow aseismic slip during 1996 or early 1997 northwest of the coseismic rupture zone and increasingly widespread relocking of shallow regions of the subduction interface after early 1997 the relative lack of afterslip in shallow regions of the subduction interface suggests that the interface lies in the unstable frictional regime and hence is strongly coupled between earthquakes by 1999 the cumulative slip moment associated with post seismic slip equaled 70 per cent of the coseismic moment with nearly all of this slip occurring downdip from the coseismic rupture zone the migration of slip after the earthquake to a deeper and presumably velocity strengthening area of the subduction interface and the logarithmic decay of afterslip conform to the qualitative and quantitative predictions of a model in which the fault kinematics are prescribed by rate and state variable frictional laws however misfits to the geodetic displacements exceed the average displacement uncertainties for all epochs implying one or more of the following 1 the elastic response is heterogeneous due to slip along unmodelled upper crustal faults or variations in the elastic properties of the crust 2 other post seismic mechanisms such as viscoelastic or poroelastic effects contribute to or possibly dominate the post seismic response 3 we have underestimated the uncertainties in the gps displacements

fault slip distribution of the 1999 mw 7 1 hector mine california earthquake estimated from satellite radar and gps measurements we use a combination of satellite radar and gps data to estimate the slip distribution of the 1999 m w 7 1 hector mine earthquake a right lateral strikeslip earthquake that occurred on a northwest southeast striking fault in the southern california mojave desert the data include synthetic aperture radar interferograms insar from both ascending and descending orbits radar amplitude image offset fields sario for both ascending and descending azimuth directions and campaign gps observations from 55 stations provided by agnew et al 2002 we model the fault with nine segments derived from the field mapped fault rupture the sario data and aftershock locations we first estimate the dip of each fault segment as well as a single constant strike slip component across each segment resulting in an average dip of 83 to the northeast and slip of up to 5 6 m then we fix the optimal fault segment dip discretize the fault segments into 1 5 km 1 5 km patches and solve for the variable slip distribution using a nonnegative least squares method that includes an appropriate degree of smoothing our preferred solution has both right lateral strike slip and reverse faulting the estimated geodetic moment is 5 93 10 19 n m m w 7 1 similar to seismological estimates indicating that there are insignificant interseismic and postseismic deformation signals in the data we find strike slip displacements of up to 6 0 m and reverse faulting of up to 1 6 m with the maximum slip located just northwest of the epicenter most of the slip is concentrated northwest and south of the epicenter little slip is found on the northeastern branch of the fault the sario data and our modeling indicate that the amount and extent of surface fault rupture were underestimated in the field

high resolution field mapping and analysis of the august october 2016 coseismic surface faulting central italy earthquakes slip distribution parameterization and comparison with global earthquakes

the effect of elastic layering on inversions of gps data for coseismic slip and resulting stress changes strike slip earthquakes we investigate the effect of depth dependent elasticity on slip inversions and coseismic stress change estimates for large strike slip earthquakes using a series of hypothetical models and the 1999 izmit turkey earthquake as examples slip inversions are performed using both semianalytical and finite element solutions for surface displacements due to a shear dislocation in layered and uniform elastic earth models we find that incorporating realistic increases to shear modulus with depth in our inversions increases recovered centroid depth and seismic potency relative to uniform elastic half space models recovered seismic moment is up to 40 greater for models incorporating depth dependent than it is for uniform elastic half space models incorporating depth dependent also increases our estimate of the maximum slip depth for the izmit turkey earthquake to at least 20 km our estimates of coseismic stress change in the upper crust do not change significantly when we incorporate depth dependent elasticity in our inversions as long as slip at depth is tuned increased to match surface displacements coseismic differential stresses in the lower crust increase by up to a factor of 3 in the near field but further from the fault stresses from layered and uniform elastic models are approximately equal with increasing depth in the mantle the ratio of modeled differential stresses for the layered and uniform elastic models approaches the ratio of mantle values for these two models we conclude that models of postseismic viscoelastic relaxation following large strike slip earthquakes should incorporate depth dependent elasticity but that uniform elastic half space models are adequate to calculate coseismic coulomb stresses in the upper crust for most triggering studies

magnetometer array studies and deep schlumberger soundings in the damara orogenic belt south west africa summary a zone of concentrated induced electric currents crossing parts of zimbabwe botswana and south west africa was discovered during a magnetovariational study conducted in 1972 in 1977 a second study was made with 27 recording magnetometers distributed across the width of south west africa between latitudes 19 and 22 s several geomagnetic disturbances were recorded with high recording efficiencies three of these time sequences were digitized for analysis magnetograms and fourier transform amplitude and phase maps in the period range 22 128 min were used to delineate the westward continuation of the conductive structure revealed by the earlier investigation the conductive zone runs approximately east west from the botswana border 21oe to 17 e longitude from here to the atlantic coast it trends in a ne sw direction anomalous fields normalized to the horizontal field at a station recording the normal field were used to obtain maximum depth estimates of around 45 km for the induced currents several deep schlumberger soundings were done over the anomalous zone and the results showed that the conductive structure is in places only 3 km from the surface and that it has a resistivity of less than 20 qm the resistivity of the upper crust outside the structure ranges from 5000 to more than 20000slm some 14 postkaroo alkaline igneous complexes occur along the course of the resistivity anomaly these intrusive complexes represent the youngest igneous activity in the damara orogenic belt and were most probably emplaced along a line of weakness in the lithosphere the resistivity anomaly would seem to delineate this line of weakness

rupture history of the 2009 l aquila italy earthquake from non linear joint inversion of strong motion and gps data 1 we image the rupture history of the 2009 l aquila central italy earthquake using a nonlinear joint inversion of strong motion and gps data this earthquake ruptured a normal fault striking along the apennines axis and dipping to the sw the inferred slip distribution is heterogeneous and characterized by a small shallow slip patch located up dip from the hypocenter 9 5 km depth and a large deeper patch located southeastward the rupture velocity is larger in the up dip than in the along strike direction this difference can be partially accounted by the crustal structure which is characterized by a high velocity layer above the hypocenter and a lower velocity below the latter velocity seems to have affected the along strike propagation since the largest slip patch is located at depths between 9 and 14 km the imaged slip distribution correlates well with the on fault aftershock pattern as well as with mapped surface breakages

joint inversion of coseismic and early postseismic slip to optimize the information content in geodetic data application to the 2009 m w 6 3 l aquila earthquake central italy when analyzing the rupture of a large earthquake geodetic data are often critical these data are generally characterized by either a good temporal or a good spatial resolution but rarely both as a consequence many studies analyze the coseismic rupture with data that also include one or more days of early postseismic deformation here we invert simultaneously for the coseismic and postseismic slip with the condition that the sum of the two models remains compatible with data covering the two slip episodes we validate the benefits of this approach with a toy model and an application to the 2009 m w 6 3 l aquila earthquake using a bayesian approach and accounting for epistemic uncertainties for the l aquila earthquake we find that if early postseismic deformation is not an explicitly acknowledged coseismic signal coseismic slip models may overestimate the peak amplitude while long term postseismic models may largely underestimate the total postseismic slip amplitude this example illustrates how the proposed approach could improve our comprehension of the seismic cycle fault frictional properties and the spatial and temporal relationship between seismic rupture afterslip and aftershocks

volcanic recycling of carbonates on mars thermal erosion of carbonate deposits by turbulently flowing lava is investigated as a means of recycling carbon dioxide back into the atmosphere of mars erosion rates of several meters day are found implying that up to hundreds of meters of carbonate could be removed over the lifetime of a flow a large fraction of the northern plains and other parts of mars were covered by lava during the hesperian and may have released the carbon dioxide trapped in carbonate deposits this period of time several times 108 years is comparable to that for the re deposition of such carbonate deposits therefore there could have existed a relatively dense atmosphere and enhanced weathering and erosion after the noachian era this may help explain the apparent observational evidence for late fluvial and lacustrine activity on mars

the southern cape conductive belt south africa its composition origin and tectonic significance abstract magnetometer array studies have led to the discovery and mapping of the southern cape conductive belt sccb crossing the southern tip of africa from west to southeast coasts the sccb lies just south of the namaqua natal belt of cratonic rocks remobilized about 1000 m y b p it is shown that it coincides with a zone of weakness which has been exploited by three major geosynclinal accumulations over some 600 m y relationships between the sccb and the basement geochronology geology and tectonics are considered in detail these relationships support the view that the conductive belt was formed by an accumulation of marine sediments and oceanic lithosphere at the top of a proterozoic subduction which stopped about 1000 to 800 m y b p associated with this subduction we propose a proterozoic range of andean mountains whose roots are now exposed in the namaqua natal belt later subduction further south near the present south coast is proposed to account for the intrusion between the south coast and the sccb of the cape granites in the time interval 600 500 m y b p there is some evidence for a third yet more distant subduction episode off permian gondwanaland after outlining this tectonic history the paper turns to a closer examination of the hypothesis that the southern cape conductive belt consists of partly serpentinized basalt accumulated at the top of a proterozoic subduction a large static magnetic anomaly which correlates with the sccb over most of its length is well fitted by a model which strongly supports this hypothesis bouguer gravity anomalies along western and central profiles likewise support the hypothesis a discussion follows of the process of formation of the proposed block of serpentinized marine rocks beginning with serpentinization of the crust near oceanic ridges by reaction of warm porous newly extruded basalt with seawater convecting through it the serpentinized basalt is stable at crustal temperatures and pressures and so is transported in the seafloor until it reaches a subduction where it accumulates because of its low density examples of such accumulations are cited finally it is shown that any iron in the olivine and pyroxene in the original basalt precipitates when these silicates are hydrated to serpentine as magnetite which is the dominant mineral conferring high electrical conductivity and high magnetic susceptibility on serpentinites in particular the beattie static magnetic anomaly requires in our model calculation a very high susceptibility readily attainable in basalt at 15 20 serpentinization the authors know of no other rock able to provide this high susceptibility a similar percentage of serpentinization provides the density required to model the gravity anomalies

ground deformation and source geometry of the 24 august 2016 amatrice earthquake central italy investigated through analytical and numerical modeling of dinsar measurements and structural geological data we investigate the ground deformation and source geometry of the 2016 amatrice earthquake central italy by exploiting alos2 and sentinel 1 coseismic differential interferometric synthetic aperture radar dinsar measurements they reveal two nnw sse striking surface deformation lobes which could be the effect of two distinct faults or the rupture propagation of a single fault we examine both cases through a single and a double dislocation planar source subsequently we extend our analysis by applying a 3 d finite elements approach jointly exploiting dinsar measurements and an independent structurally constrained 3 d fault model this model is based on a double fault system including the two northern gorzano and redentore vettoretto faults ngf and rvf which merge into a single wsw dipping fault surface at the hypocentral depth 8 km the retrieved best fit coseismic surface deformation pattern well supports the exploited structural model the maximum displacements occur at 5 7 km depth reaching 90 cm on the rvf footwall and 80 cm on the ngf hanging wall the von mises stress field confirms the retrieved seismogenic scenario

moment tensor analysis of the central italy earthquake sequence of september october 1997 the larger earthquakes in the umbria marche central italy seismic sequence of september october 1997 are analyzed using long period seismograms from the mediterranean seismographic network mednet and additional data from the global seismographic network gsn we modify the harvard centroid moment tensor cmt algorithm to allow moment tensor inversion of long period waveforms primarily rayleigh and love waves for small earthquakes at local to regional distances 5 5 in the sequence moment tensors have previously been determined using teleseismic waveforms and standard methods of analysis our results agree well with those of earlier studies we determine additional moment tensors for the largest foreshock and 10 aftershocks with mw 4 2 the earthquakes are characterized by normal faulting mechanisms with a ne sw tension axis and the presumed fault plane dips towards the sw only one of the fourteen events studied has a different faulting geometry indicating instead right lateral strike slip faulting on a plane oriented approximately e w or left lateral faulting on a plane oriented n s the september 26 mainshock 09 40 ut accounts for only approximately 50 of the total moment release in the sequence

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

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

crustal seismic velocity in the marche region central italy computation of a minimum 1 d model with seismic station corrections a 1 d velocity model for the marche region central italy was computed by inverting p and s wave arrival times of local earthquakes a total of 160 seismic events with a minimum of ten observations a travel time residual b0 8 s and an azimuthal gap lower than 180 have been selected this minimum 1 d velocity model is complemented by station corrections which can be used to take into account possible near surface velocity heteroge neities beneath each station using this new p wave velocity model and the program hypoellipse lahr 1999 the selected local events were relocated earthquake locations in this study are of higher quality with respect to the original ones the obtained minimum 1 d velocity model can be used to improve the routine earthquake locations and represents a further step towards more detailed seismotectonic studies of the area

decollement depth versus accretionary prism dimension in the apennines and the barbados 1 along representative cross sections of the apennines and the northern barbados accretionary prisms we measured the area the decollement depth the angle a of the upper envelope and the angle b of the dip of the regional monocline the continental sections of the apennines accretionary prism have a deeper decollement than the oceanic sections of the northern barbados 6 10 km depth and 1 km depth respectively because the sediment pile is thinner on the incoming barbados plate and its denser oceanic structure is more easily subducted considering the frontal 50 km the apennines have an average cross sectional area of 500 km 2 and the northern barbados ridge of 100 km 2 the total area is a function of the depth of the decollement plane therefore at a given amount of subduction the deeper the decollement depth is the bigger the area of the wedge will result assuming negligible compaction and erosion as a consequence the larger area volume and higher elevation of the apennines with respect to the barbados is determined by the apenninic deeper decollement despite these differences the geometry of both decollements is in some cases comparable in particular close to the boundary between the crystalline crust and the sediment pile where the main density and strength contrasts are concentrated variations in depth of the decollement occur moving along strike in both accretionary prisms the geometry of the prisms is further controlled by the different values of a and b their sum and the distance of the accretionary prism relative to the subduction hinge index terms 8099 structural geology general or miscellaneous 8150 tectonophysics evolution of the earth plate boundary general 3040 8122 tectonophysics dynamics gravity and tectonics keywords decollement depth accretionary prism apennines barbados citation bigi s f lenci c doglioni j c moore e carminati and d scrocca decollement depth versus

finite element inversion of dinsar data from the mw 6 3 l aquila earthquake 2009 italy 1 fault slip distribution is usually retrieved from geodetic data assuming that the local crust is an elastic homogeneous and isotropic half space in the last decades spatially dense geodetic data e g dinsar maps have highlighted complex patterns of coseismic deformation that require new modeling tools such as numerical methods able to represent rheological and geometrical complexities of the earth s crust in this work we develop a procedure to perform inversion of geodetic data based on the finite element method accounting for a more realistic description of the local crust the method is applied to the 2009 l aquila earthquake mw 6 3 using dinsar images of the coseismic displacement results highlight the non negligible influence of the medium structure homogeneous and heterogeneous models show discrepancies up to 20 in the fault slip distribution values furthermore in the heterogeneous models a new area of slip appears above the hypocenter we also perform a resolution study showing that the information about fault slip distributions retrieved from geodetic data should be considered as averaged on surrounding patches

impedance of black shale from munsterland 1 borehole an anomalously good conductor summary black shale containing about 5 per cent organic matter has very low electrical resistivity in comparison to shale which contains no organic matter the low resistivity of the black shale is attributed to carbon produced by pyrolysis reactions associated with diagensis located at grain boundaries in the black shale some conductivity anomalies in the earth s crust and upper mantle may be caused by carbon produced in this manner