systematic comparisons of earthquake source models determined using insar and seismic data abstract robust earthquake source parameters e g location seismic moment fault geometry are essential for reliable seismic hazard assessment and the investigation of large scale tectonics they are routinely estimated using a variety of data and techniques such as seismic data and more recently interferometric synthetic aperture radar insar comparisons between these two datasets are frequently made although not usually in a comprehensive way this review compares source parameters from global and regional seismic catalogues with those from a recent database of insar parameters which has been expanded with 18 additional source models for this study we show that moment magnitude mw estimates agree well between the two datasets with a trend for thrust events modelled using insar to have slightly larger mw estimates earthquake locations determined using insar agree well with those reported in regional catalogues with a median difference of 6 3 km between them which is smaller than for global seismic catalogues we also investigate the consistency of source parameters and source directivity by comparing isc hypocentres with gcmt and icmt centroid locations for earthquakes with mw 6 5 in some cases the source directivity is qualitatively comparable with previous studies especially when comparing isc and icmt locations the average difference between insar determined depths and those in the ehb catalogue is reduced if a layered half space is used in the inversion of insar data overall faulting geometry strike dip and rake angles remain in good agreement with values from the gcmt catalogue and any large discrepancies can be attributed to tradeoffs between parameters with continued investment in satellites for radar interferometry insar is a valuable technique for the estimation of earthquake source parameters the observed trends and discrepancies between insar and seismically determined source parameters are the result of issues with the data different inversion techniques and the assumed earth structure model

the 1976 friuli ne italy thrust faulting earthquake a reappraisal 23 years later we revisit the 1976 friuli earthquake sequence by combining hypocenters relocation long period surface wave inversion field geology and strong motion modelling we show that fault related folding is the main active deformation by which the seismic energy was released during the main shock ms 6 5 and that some of the surface effects reported in 1976 correspond to widespread bedding planes displacements induced by flexural slip folding the fault evolved from blind to semi blind along strike showing the control of the inherited structural geology on the fault surface break and rupture arrest our fault model produces waveforms that fit the accelerograms recorded in the area

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

tomographic images of the el asnam fault zone and the evolution of a seismogenic thrust related fold the p wave velocity structure of the upper 9 km of the el asnam algeria fault zone the site of the ms7 3 earthquake october 10 1980 is obtained by inverting arrival times from 310 selected aftershocks computed crustal structure and relocation of aftershocks yield new insight on the structural geology of the area and help to clarify the evolution of fault related folding and the complexity of the rupture episodes during the el asnam earthquake the correlation between tomograms and geologic structures observed at the surface and inferred at depth delineates local heterogeneities of the upper crust there is evidence for distinct large scale structural trends consisting of two main thrusts with antithetic reverse faults seismic tomography provides reasonable constraints on the el asnam fault related fold geometry pointing out a complex preexisting structure along which the rupture evolution is controlled by the heterogeneous crust we propose that the main shock originated along an inverted normal fault bordering the pre neogene basement lateral lithologic heterogeneities obtained by seismic tomography reflect the fault segmentation and geometrical discontinuities along strike in agreement with the tectonic pattern

seismic potential revealed by surface folding 1983 coalinga california earthquake the 2 may 1983 coalinga california earthquake magnitude 6 5 failed to rupture through surface deposits and instead elastically folded the top few kilometers of the crust the subsurface rate of fault slip and the earthquake repeat time are estimated from seismic geodetic and geologic data three larger earthquakes up to magnitude 7 5 during the past 20 years are also shown to have struck on reverse faults concealed beneath active folds

ambient noise tomography of the pyrenees and the surrounding regions inversion for a 3 d vs model in the presence of a very heterogeneous crust we thank all participants in the fieldwork and the municipalities and landlords that hosted a pyrope temporary station we also acknowledge sismob the french seismic mobile pool a com ponent of the resif research facility for providing us with the seismological instrumentation for the temporary deployments we used data from the fr and rd resif g geoscope and ca institut cartogr afic i geol ogic de catalunya permanent net works resif http portal resif fr is a national research infras tructure recognized as such by the french ministry of higher education and research resif is managed by the resif con sortium composed of 18 research institutions and universities in france resif additionally supported by a public grant overseen by the french national research agency anr as part of the investissements d avenir program reference anr 11 eqpx 0040 andthefrenchministryofecology sustainabledevelopment and energy the pyrope experiment was supported by the french research agency anr blanc program project pyrope anr 09 blan 0229 this is a contribution of the team consolider ingenio 2010 topo iberia csd2006 00041 c

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

zemmouri earthquake rupture zone mw 6 8 algeria aftershocks sequence relocation and 3d velocity model 1 we analyze the aftershocks sequence of the zemmouri thrust faulting earthquake 21 may 2003 mw 6 8 located east of algiers in the tell atlas the seismic sequence located during 2 months following the mainshock is made of more than 1500 earthquakes and extends ne sw along a 60 km fault rupture zone crossing the coastline the earthquake relocation was performed using handpicked p and s phases located with the tomodd in a detailed 3d velocity structure of the epicentral area contrasts between velocity patches seem to correlate with contacts between granitic volcanic basement rocks and the sedimentary formation of the eastern mitidja basin the aftershock sequence exhibits at least three seismic clouds and a well defined se dipping main fault geometry that reflects the complex rupture the distribution of seismic events presents a clear contrast between a dense sw zone and a ne zone with scattered aftershocks we observe that the mainshock locates between the sw and ne seismic zones it also lies at the nns sse contact that separates a basement block to the east and sedimentary formations to the west the aftershock distribution also suggests fault bifurcation at the sw end of the fault rupture with a 20 km long n 100 trending seismic cluster with a vertical fault geometry parallel to the coastline juxtaposed another aftershock cloud may correspond to 75 se dipping fault the fault geometry and related sw branches may illustrate the interference between pre existing fault structures and the sw rupture propagation the rupture zone related kinematics and velocity contrasts obtained from the aftershocks distribution are in agreement with the coastal uplift and reflect the characteristics of an active zone controlled by convergent movements at a plate boundary

the 2003 boumerdes algeria earthquake regional moment tensor analysis 1 we used regional broadband seismograms to determine seismic moment tensors for the destructive may 21 2003 boumerdes algeria mw 7 0 earthquake and its larger aftershocks fully automatic inversions using near real time data provided solutions for seven mw 4 7 events within 90 minutes after event occurrence after adding off line data we manually obtained 30 solutions mw 3 8 from may 2003 to january 2004 all have shallow source depths 6 21 km the median p axis orientation 338 of 24 thrust and four strike slip events is consistent with africa eurasia plate motion 330 the main shock hypocenter at 8 10 km depth at the coastline and its shallow southward dip 25 5 puts the fault surface trace 15 20 km offshore consistent with documented seafloor deformation at the base of the continental slope a main shock rupture length of about 50 km is deduced from first day aftershocks and location of strike slip events the strike slip events probably define the western rupture end and indicate a left step of main convergence fault strike variability of thrust events suggests fault orientation changes and possibly fault segmentation

rupture parameters of the 2003 zemmouri mw 6 8 algeria earthquake from joint inversion of interferometric synthetic aperture radar coastal uplift and gps 1 we study the surface deformation associated with the 21 may 2003 mw 6 8 zemmouri algeria earthquake the strongest seismic event felt in the algiers region since 1716 the thrust earthquake mechanism and related surface deformation revealed an average 0 50 m coastal uplift along 55 km long coastline we obtain coseismic interferograms using envisat advanced synthetic aperture radar asar is2 and radarsat standard beam st4 data from both the ascending and descending orbits of envisat satellite whereas the radarsat data proved useful only in the descending mode while the two radarsat interferograms cover the earthquake area envisat data cover only the western half of the rupture zone although the interferometric synthetic aperture radar insar coherence in the epicenter area is poor deformation fringes are observed along the coast in different patches in the boumerdes area the maximum coseismic deformation is indicated by the high gradient of fringes visible in all interferograms in agreement with field measurements tape differential gps leveling and gps to constrain the earthquake rupture parameters we model the interferograms and uplift measurements using elastic dislocations on triangular fault patches in an elastic and homogeneous half space we invert the coseismic slip using first a planar surface and second a curved fault both constructed from triangular elements using poly3dinv program that uses a damped least square minimization the best fit of insar coastal uplift and gps data corresponds to a 65 km long fault rupture dipping 40 to 50 se located at 8 to 13 km offshore with a change in strike west of boumerdes from n60 65 to n95 105 the inferred rupture geometry at depth correlates well with the seismological results and may have critical implications for the seismic hazard assessment of the algiers region

fike et al reply replying to k grey c r calver doi 10 1038 nature06360 2007 calver and grey1 point out the difficulties of relating the australian acritarch record to the global record of environmental change this results from the lack of documented stratigraphic sections that have overlapping chronologies of both acritarch evolution and global chemostratigraphic proxies such as 13ccarb and we agree that coupled records are required to confirm our hypothesis2 until such records exist any correlations between australian acritarch bearing strata and strata containing records of global secular variations in 13ccarb are necessarily tenuous this uncertainty however does not affect the principal conclusion of our paper which emphasizes the evidence for sequential chemical oxidation of the ediacaran ocean our inferred correlation between chemical oxidation and biological evolution is supported by subsequent results on strata containing strong geochronologic tie points and a robust biostratigraphic and chemostratigraphic record3 4

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

moment tensor solutions for small and moderate earthquakes in the ibero maghreb region 1 we applied time domain moment tensor inversion of local and regional waveforms to small and moderate mw 3 5 5 7 shallow earthquakes from the iberian peninsula northern morocco and northern algeria for the 6 years period from november 1995 to march 2002 and the previous network of autonomously recording seismograms nars experiment moment tensor solutions were obtained for 58 events considerably increasing the total number of available solutions in the study area for each event we performed a moment tensor inversion and a double couple grid search for simple faulting events the grid search is valuable as a quality test for its ability to reveal potential ambiguities of the solutions and to assess confidence limits of fault plane parameters or principal axes orientation the computed mechanisms show regional consistency a large part of the iberian peninsula is characterized by normal faulting mechanisms with sw ne oriented t axes thrusting and se nw compression is dominant in algeria in the alboran sea the westernmost part of the mediterranean and the transition between both regimes strike slip mechanisms dominate with approximately n s oriented p axes this pattern suggests a regional anomaly characterized by clockwise rotation of the principal horizontal stress orientations

slip distribution of the 2003 boumerdes zemmouri earthquake algeria from teleseismic gps and coastal uplift data 1 using a joint inversion of seismological waveforms and ground displacement observations we estimate several parameters of the fault geometry and rupture process of the mw 6 9 may 21 2003 boumerdes zemmouri earthquake the relocated epicenter is considered as a known parameter total rupture length rupture duration and maximum slip are 55 km from 3 4 e to 4 0 e 12 s and 3 m the modeled south dipping reverse fault oriented ene wsw outcrops a few km offshore which is consistent with the absence of observed surface rupture inland two shallow and relatively localized slip zones are found on both sides of the hypocenter to the sw between boumerdes and zemmouri slip is concentrated between 11 and 2 km depth to the ne between zemmouri and dellys slip is concentrated between 6 km depth and the sea floor various resolution tests indicate that our model is well constrained by the available data and help understanding which data constrains each parameter of the model

reply to comment by j deverchere et al on zemmouri earthquake rupture zone mw 6 8 algeria aftershocks sequence relocation and 3d velocity model

constraining the slip distribution and fault geometry of the mw 7 9 3 november 2002 denali fault earthquake with interferometric synthetic aperture radar and global positioning system data the m w 7 9 denali fault earthquake dfe is the largest continental strike slip earthquake to occur since the development of interferometric synthetic aperture radar insar we use five interferograms constructed using radar images from the canadian radarsat 1 satellite to map the surface deformation at the western end of the fault rupture additional geodetic data are provided by displacements observed at 40 campaign and continuous global positioning system gps sites we use the data to determine the geometry of the susitna glacier fault thrusting on which initiated the dfe and to determine a slip model for the entire event that is consistent with both the insar and gps data we find there was an average of 7 3 0 4 m slip on the susitna glacier fault between 1 and 9 5 km depth on a 29 km long fault that dips north at 41 0 7 and has a surface projection close to the mapped rupture on the denali fault a simple model with large slip patches finds a maximum of 8 7 0 7 m of slip between the surface and 14 3 0 2 km depth a more complex distributed slip model finds a peak of 12 5 0 8 m in the upper 4 km significantly higher than the observed surface slip we estimate a geodetic moment of 670 10 10 18 n m m w 7 9 consistent with seismic estimates lack of preseismic data resulted in an absence of insar coverage for the eastern half of the dfe rupture a dedicated geodetic insar mission could obviate coverage problems in the future

seven years of postseismic deformation following the 2003 mw 6 8 zemmouri earthquake algeria from insar time series 1 we study the postseismic surface deformation of the mw 6 8 2003 zemmouri earthquake northern algeria using the multi temporal small baseline insar technique insar time series obtained from 31 envisat asar images from 2003 to 2010 reveal sub cm coastline ground movements between cap matifou and dellys two regions display subsidence at a maximum rate of 2 mm yr in cap djenet and 3 5 mm yr in boumerdes these regions correlate well with areas of maximum coseismic uplifts and their association with two rupture segments inverse modeling suggest that subsidence in the areas of high coseismic uplift can be explained by afterslip on shallow sections 5 km of the fault above the areas of coseismic slip in agreement with previous gps observations the earthquake impact on soft sediments and the ground water table southwest of the earthquake area characterizes ground deformation of non tectonic origin the cumulative postseismic moment due to 7 years afterslip is equivalent to an mw 6 3 earthquake therefore the postseismic deformation and stress buildup has significant implications on the earthquake cycle models and recurrence intervals of large earthquakes in the algiers area

stress transfer among en echelon and opposing thrusts and tear faults triggering caused by the 2003 mw 6 9 zemmouri algeria earthquake stress transfer among en echelon and opposing thrusts and tear faults triggering caused by the 2003 m w 6 9 zemmouri algeria earthquake 1 the essential features of stress interaction among earthquakes on en echelon thrusts and tear faults were investigated first through idealized examples and then by study of thrust faulting in algeria we calculated coseismic stress changes caused by the 2003 m w 6 9 zemmouri earthquake finding that a large majority of the zemmouri afterslip sites were brought several bars closer to coulomb failure by the coseismic stresses while the majority of aftershock nodal planes were brought closer to failure by an average of 2 bars further we calculated that the shallow portions of the adjacent thenia tear fault which sustained 0 25 m slip were brought 2 bars closer to failure we calculated that the coulomb stress increased by 1 5 bars on the deeper portions of the adjacent boumerdes thrust which lies just 10 20 km from the city of algiers both the boumerdes and thenia faults were illuminated by aftershocks over the next 6 years the entire south dipping thrust system extending 80 km to the southwest experienced an increased rate of seismicity the stress also increased by 0 4 bar on the east sahel thrust fault west of the zemmouri rupture algiers suffered large damaging earthquakes in a d 1365 and 1716 and is today home to 3 million people if these shocks occurred on the east sahel fault and if it has a 2 mm yr tectonic loading rate then enough loading has accumulated to produce a m w 6 6 6 9 shock today thus these potentially lethal faults need better understanding of their slip rate and earthquake history among en echelon and opposing thrusts and tear faults triggering caused by the 2003 m w 6 9 zemmouri algeria earthquake

integrating high precision aftershock locations and geodetic observations to model coseismic deformation associated with the 1995 kozani grevena earthquake greece 1 we integrate high precision aftershock locations with geodetic inverse modeling to create a more complete kinematic model for the kozani grevena earthquake sequence using the double difference algorithm we have improved relative hypocentral locations by a factor of 7 and thus imaged the details of the fault network associated with the seismic sequence the interpreted fault network consists of multiple segments including 1 a master normal fault that strikes nearly due west and dips toward the north at 43 extending from 6 to 15 km depth 2 an upper segment that connects the top of the seismicity to the observed surface ruptures and dips 70 3 hanging wall antithetic faults 4 a more steeply dipping southwest striking linking structure at the southwest end of the rupture and 5 a separate south dipping segment at the southwestern end of the aftershock cluster the imaged fault segment dimensions orientations and geometric relationships are consistent with regional fault patterns using slip inversion on triangular dislocation patches we calculate variable slip on the imaged three dimensional fault network that best fits the surface displacements observed by satellite interferometric synthetic aperture radar insar in our preferred model we find that the majority of slip occurred at depth on the west and southwest striking segments by comparing these results to a planar fault model derived solely from the insar data using nonlinear inversion methods we demonstrate that the three dimensional model improves the fit to the geodetic data while incorporating the observations of surface rupturing and aftershock distributions

the 21 may 2003 zemmouri algeria earthquake mw 6 8 relocation and aftershock sequence analysis 1 a strong earthquake mw 6 8 struck the coastal region east of algiers and the tell atlas of algeria on 21 may 2003 and was responsible of severe damage and about 2400 casualties the coastal mainshock was followed by a large number of aftershocks the largest reaching mw 5 8 on 27 may 2003 we study the mainshock first major aftershocks and about 900 events recorded by temporary seismic stations using master event approach and double difference dd methods although the seismic station array has a large gap coverage the dd algorithm provides with an accurate aftershocks location the mainshock hypocenter relocation is determined using three major aftershocks 5 0 mw 5 8 chosen as master events the new mainshock location shifted on the coastline 36 83n 3 65e at 8 10 km depth seismic events extend to about 16 km depth and form a n 55 60 e trending and 45 55 se dipping fault geometry up to now it is the unique among the recently studied seismic events of the tell atlas of algeria mainshock and aftershocks relocation the thrust focal mechanism harvard cmt n 57 44 se dip 71 rake and the seismic moment 2 86 1019 nm infer a 50 km long fault rupture that may appear at the sea bottom at 6 to 12 km offshore north of the coastline the zemmouri earthquake occurred along the complex thrust and fold system of the tell atlas and provides with new constraints on the earthquake hazard evaluation in northern algeria

deformation on nearby faults induced by the 1999 hector mine earthquake interferometric synthetic aperture radar observations of surface deformation due to the 1999 hector mine earthquake reveal motion on several nearby faults of the eastern california shear zone we document both vertical and horizontal displacements of several millimeters to several centimeters across kilometer wide zones centered on pre existing faults portions of some faults experienced retrograde that is opposite to their long term geologic slip motion during or shortly after the earthquake the observed deformation likely represents elastic response of compliant fault zones to the permanent co seismic stress changes the induced fault displacements imply decreases in the effective shear modulus within the kilometer wide fault zones indicating that the latter are mechanically distinct from the ambient crustal rocks

global compilation of interferometric synthetic aperture radar earthquake source models 1 comparisons with seismic catalogs 1 while many earthquakes have now been studied using interferometric synthetic aperture radar insar data a full assessment of the quality and additional value of insar source parameters compared to seismological techniques is still lacking we compile a catalog of source models obtained using insar and estimate the corresponding centroid moment tensor cmt parameters we refer to this compilation as the icmt archive we compare source parameters from over 70 insar studies of 57 global earthquakes with those in the global cmt gcmt international seismological centre isc and engdahl hilst buland ehb seismic catalogs we find an overall good agreement between fault strike dip and rake values in the gcmt and icmt archives likewise the differences in seismic moment between these two archives are relatively small and we do not find support for previously suggested trends of insar leading to larger moments than seismic data however epicentral locations show substantial discrepancies which are larger for the gcmt median differences of 21 km than for the ehb and isc catalogs median differences of 10 km since insar data have a high spatial resolution and thus should map epicentral locations accurately this allows us to obtain a first independent estimate of epicentral location errors in the seismic catalogs earthquake depths from insar are systematically shallower than those in the ehb catalog with a median of differences of 5 km while this trend may be partly due to unmodeled crustal complexity it is also compatible with the observation that the rupture of crustal earthquakes tends to propagate upward in the seismogenic layer

inversion of moment tensor focal mechanisms for active stresses around the microcontinent iberia tectonic implications the iberian microcontinent and its connected oceanic crust are affected by deformations related to the eurasian african plate boundary active stress inversions from populations of moment tensor focal mechanisms have been performed around and inside the iberian peninsula using a total of 213 moment tensor estimates main results are 1 the tensorial solutions show better consistency and lower misfits compared to those obtained previously from first p arrival focal mechanisms 2 along the eurasia africa western boundary the type of active stresses progressively changes easternwards from triaxial extension to uniaxial compression along the terceira ridge the gloria fault zone and the gulf of cadiz 3 in the betics alboran rif zone uniaxial extension predominates with shmax n155oe trending 4 in n algeria uniaxial compression reappears 5 the iberian foreland is currently under strike slip to uniaxial extension tensorial conditions

integrating high precision aftershock locations and geodetic observations to model coseismic deformation associated with the 1995 kozani grevena earthquake greece kinematic model of the kozani earthquake

geodetic measurements of crustal deformation in the western mediterranean and europe geodetic measurements of crustal deformation over large areas deforming at slow rates 5 mm yr over more than 1000 km such as the western mediterranean and western europe are still a challenge because 1 these rates are close to the current resolution of the geodetic techniques 2 inaccuracies in the reference frame implementation may be on the same order as the tectonic velocities we present a new velocity field for western europe and the western mediterranean derived from a rigorous combination of 1 a selection of sites from the itrf2000 solution 2 a subset of sites from the european permanent gps network solution 3 a solution of the french national geodetic permanent gps network rgp and 4 a solution of a permanent gps network in the western alps regal the resulting velocity field describes horizontal crustal motion at 64 sites in western europe with an accuracy on the order of 1 mm yr or better its analysis shows that central europe behaves rigidly at a 0 4 mm yr level and can therefore be used to define a stable europe reference frame in that reference frame we find that most of europe including areas west of the rhine graben the iberian peninsula the ligurian basin and the corsica sardinian block behaves rigidly at a 0 5 mm yr level in a second step we map recently published geodetic results in the reference frame previously defined geodetic data confirm a counterclockwise rotation of the adriatic microplate with respect to stable europe that appears to control the strain pattern along its boundaries active deformation in the alps apennines and dinarides is probably driven by the independent motion of the adriatic plate rather than by the africa eurasia convergence the analysis of a global gps solution and recently published new estimates for the african plate kinematics indicate that the africa eurasia plate motion may be significantly different from the nuvel1a values in particular geodetic solutions show that the convergence rate between africa and stable europe may be 30 60 slower than the nuvelia prediction and rotated 10 30 counterclockwise in the mediterranean

seismotectonics of the el asnam earthquake the mechanism of the el asnam earthquake of 10 october 1980 ms 7 2 the strongest recorded in northwestern africa is compatible with a convergence between the african and european plates the thrust is also consistent with field observations and with long period data from the global network aftershocks cluster around the fault trace with a maximum depth of 12 km maximum vertical displacement is 6 m and there is some left lateral motion the fault trace of the 1954 earthquake at beni rached was also reactivated

the 1994 2004 al hoceima morocco earthquake sequence conjugate fault ruptures deduced from insar abstract we study the may 26 1994 mw 6 0 and february 24 2004 mw 6 4 earthquakes that affected the al hoceima region of northern morocco these events are the two strongest earthquakes recorded in this region yet the exact location kinematics and relationships between these earthquakes are poorly known since neither of them produced surface ruptures using synthetic aperture radar interferometry insar we mapped the surface displacement field of the two earthquakes to characterize their seismic source parameters analysis of the interferograms constructed from ascending and descending orbits for both earthquakes and subsequent elastic modeling using slip inversions on triangular fault patches suggest that the two mainshocks occurred on blind conjugate strike slip faults the 1994 earthquake being associated with n23 e trending left lateral fault and the 2004 earthquake with n45 w trending right lateral fault this result contradicts previous inferences on the kinematics location and rupture geometry of the earthquakes deduced from conventional analyses of seismic waveforms and aftershocks distribution the insar analysis reveals the fragmentation of the rif mountain throughout a complex network of conjugate blind faults consistent with the transpression tectonics along the plate boundary in north africa although the two earthquakes took place in the rif thrust and fold belt the late quaternary deformation indicates e w extension in agreement with the nw se and ne sw trending conjugate strike slip faulting

displacement field and slip distribution of the 2005 kashmir earthquake from sar imagery 1 the 8th october 2005 kashmir earthquake mw 7 6 involved primarily thrust motion on a ne dipping fault sub pixel correlation of envisat sar images gives the location of the 80 km long fault trace within 300 800 m and a 3d surface displacement field with a sub metric accuracy covering the whole epicentral area the slip distribution inverted using elastic dislocation models indicates that slip occurs mainly in the upper 10 km between the cities of muzaffarabad and balakot the rupture reached the surface in several places in the hanging wall horizontal motions show rotation from pure thrust to oblique right lateral motion that are not observed in the footwall a segmentation of the fault near muzaffarabad is also suggested north of the city of balakot slip decreases dramatically but a diffuse zone of mainly vertical surface displacements which could be post seismic exists further north where most of the aftershocks occur aligned along the nw se indus kohistan seismic zone

seismic image of the cantabrian mountains in the western extension of the pyrenees from integrated escin reflection and refraction data abstract integrated analysis of normal incidence and large aperture seismic reflection data collected in 1992 and 1993 within the spanish escin and complementary projects provide a first complete n s crustal transect across the northern iberian peninsula and continental margin images of the crustal structure of the cantabrian mountains and their transition to the duero basin and to the cantabrian margin are obtained from a a 65 km long vertical reflection profile escin 2 on land b a 200 km long reversed refraction profile and c wide angle recordings of the marine escin 4 profile consistent results between reflectivity pattern and velocity depth distribution reveal important lateral variations in the deep structure the reflective crust imaged in the escin 2 profile changes its attitude from sub horizontal beneath the duero basin to north dipping beyond the mountain front basement thrusts are observed in the upper crust merging into a detachment at 6 s twt and may have triggered the alpine uplift of the range the moho is identified at the bottom of the reflective lower crust and deepens from 12 to 15 s at the northern end of the profile about 35 km inland modelling of the refraction data laterally extends the seismic image and provides evidence for variscan crustal features beneath the duero basin northwards the velocity in the lower crust decreases and the moho constrained by the wide angle data from profile escin 2 deepens to about 60 km ending abruptly at the shoreline the velocity depth model is constrained along the asturian platform up to the continental slope where the crust mantle boundary is located at 24 km depth this margin moho shows a progressive deepening southwards and extends to the coast where it is found at 30 km depth the present seismic data support an important alpine reworking and thickening of the crust under the cantabrian mountains the onshore offshore transition is marked by an imbrication of two crusts of very different thicknesses this signature offers a strong parallelism with the one previously observed further east across the pyrenees in the ecors seismic profile

characterization of shallow geology by high frequency seismic noise tomography summary to study the applicability of the passive seismic interferometry technique to near surface geological studies seismic noise recordings from a small scale 2 d array of seismic stations were performed in the test site of nauen germany rayleigh wave green s functions were estimated for different frequencies a tomographic inversion of the traveltimes estimated for each frequency from the green s functions is then performed allowing the laterally varying 3 d surface wave velocity structure below the array to be retrieved at engineering geotechnical scales furthermore a 2 d s wave velocity cross section is obtained by combining 1 d velocity structures derived from the inversion of the dispersion curves extracted at several points along a profile where other geophysical analyses were performed it is shown that the cross section from passive seismic interferometry provides a clear image of the local structural heterogeneities that are in excellent agreement with georadar and geoelectrical results such findings indicate that the interferometry analysis of seismic noise is potentially of great interest for deriving the shallow 3 d velocity structure in urban areas

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

fault location and source process of the boumerdes algeria earthquake inferred from geodetic and strong motion data the boumerdes earthquake occurred on a fault whose precise location offshore the algerian coast was unknown geodetic data are used to determine the absolute position of the fault the fault might emerge at about 15 km offshore accelerograms are used to infer the space time history of the rupture using a two step inversion in the spectral domain the observed strong motion records agree with the synthetics for the fault location inferred from geodetic data the fault plane ruptured for about 18 seconds the slip distribution on the fault indicates one asperity northwest of the hypocenter with maximum slip amplitude about 3 m this asperity is probably responsible for most of the damage another asperity with slightly smaller slip amplitude is located southeast of the hypocenter the rupture stops its westward propagation close to the thenia fault a structure almost perpendicular to the main fault

whole mantle p wave travel time tomography abstract a method of tomographic inversion to obtain three dimensional velocity perturbations in the earth s whole mantle has been developed and applied to more than two million p wave arrival time data reported by international seismology center isc the model is parameterized with 32 768 blocks the divisions in latitude longitude and radius are 32 64 and 16 respectively horizontal cell size is 5 6 5 6 the layer thicknesses vary with depth 29 km just below the surface and 334 km just above the core mantle boundary starting from a spherically symmetric earth model we obtained a three dimensional model using the following iterative procedures first we relocated all the events second we backprojected the residual into the whole mantle third we refined the spherically symmetric earth model the solutions have been converged in five iterations we adopted the following techniques in the backprojection procedure the first order smoothness was introduced as a damping which makes the solution independent of the starting model and its apparent fluctuation minimal the basic equations for delay times and smoothness are solved using the conjugate gradient method an iterative method which guarantees the convergence of solution into the exact least squares solution the weight on the smoothness i e the damping factor was objectively determined by a simplified cross validation technique the final solution was obtained as an average of the ten solutions each of which was derived from one tenth of the total data set the reliability of the solution is examined in two ways 1 mapping the resolution given by the reconstruction of checkerboard patterns and 2 mapping the variance given from the gaussian noise input this is the first result which delineates the whole mantle structure with its reliability mapping the longest wavelength anomalies of the lower mantle are similar to those of previous studies by dziewonski 1984 and hager and clayton 1989 however the shorter wavelength patterns have many discrepancies the fast anomalies of the uppermost mantle beneath the shield and the slow anomalies beneath the active tectonic regions are clearly seen we also revealed the l 2 pattern at the transition zone reported by the previous surface wave and free oscillation studies the most striking feature is that of the fast anomalies lying along the extension of the large subducting plate up to depths of about 1000 km or more the resolving powers in these regions are generally good

european continuous active tectonic strain stress map this paper shows a new continuous strain stress map for europe obtained from the direct inversion of earthquake focal mechanisms calculated from the centroid tensor method a total of 1608 focal mechanisms have been selected with several quality criteria from different catalogues cmt harvard eth med net i g n and i a g from 1973 to the present day values for the maximum horizontal shortening direction and brittle strain stress regime defined by the k ratio ey ez horizontal maximum vertical strain have been calculated following in europe and pannonian basin the slip model of tri axial deformation the individual results including dey and the shape of the active brittle strain ellipsoid have been interpolated to a final 15 regular grid taking into account the relationship between the tectonic horizontal strain stress value and the vertical load both continuous strain regime and maximum horizontal shortening dey maps show a good correlation with the primary tectonic forces generated along the plate boundaries plate kinematics and also some local perturbations related with main crustal heterogeneities and topography as well as significant spatial variations in integrated crustal strength

ediacaran oxidation and biotic evolution arising from d a fike et al 744 747 2006 10 1038 nature05345 fike et al reply the link between the radiation of various lineages of eukaryotes in the latest proterozoic and massive environmental changes oxygenation global ice ages and bolide impact is the focus of much research interest fike et al 1 use carbon and sulphur isotope chemostratigraphic data from oman to propose three stages of oxidation in the ediacaran oceans and link the second and third stages to eukaryote diversification the second stage signalled by strongly 13c depleted sedimentary carbonates the shuram excursion is believed to result from oxidation of a large deep ocean reservoir of organic carbon1 fike et al use our data2 3 to assert that a correlative carbon isotope excursion in australia coincided with the initial diversification of acanthomorphic acritarchs peak diversity is claimed to have coincided with subsequent deposition of 13c enriched carbonate and the third oxidation stage however the authors seem to have misinterpreted our data which instead indicate that diversification significantly preceded the shuram excursion this weakens their argument for a link between the inferred oxidation events and eukaryote evolution

rayleigh wave phase velocity maps of tibet and the surrounding regions from ambient seismic noise tomography ambient noise tomography is applied to the significant data resources now available across tibet and surrounding regions to produce rayleigh wave phase speed maps at periods between 6 and 50 s data resources include the permanent federation of digital seismographic networks five temporary u s program for array seismic studies of the continental lithosphere passcal experiments in and around tibet and chinese provincial networks surrounding tibet from 2003 to 2009 totaling 600 stations and 150 000 interstation paths with such a heterogeneous data set data quality control is of utmost importance we apply conservative data quality control criteria to accept between 5000 and 45 000 measurements as a function of period which produce a lateral resolution between 100 and 200 km across most of the tibetan plateau and adjacent regions to the east misfits to the accepted measurements among passcal stations and among chinese stations are similar with a standard deviation of 1 7 s which indicates that the final dispersion measurements from chinese and passcal stations are of similar quality phase velocities across the tibetan plateau are lower on average than those in the surrounding nonbasin regions phase velocities in northern tibet are lower than those in southern tibet perhaps implying different spatial and temporal variations in the way the high elevations of the plateau are created and maintained at short periods 20 s very high velocities are imaged in the tarim basin the ordos block and the sichuan basin these phase velocity dispersion maps provide information needed to construct a 3 d shear velocity model of the crust across the tibetan plateau and surrounding regions

locations of selected small earthquakes in the zagros mountains the zagros mountains of southern iran are marked by a zone of high seismicity and accommodate a significant portion of the convergence between arabia and eurasia due to the lack of dense local seismic or geodetic networks the inferred kinematics of the collision in iran is mainly based on catalogs of teleseismically determined earthquake locations we surveyed all mw 4 5 earthquakes in the harvard centroid moment tensor hcmt and international seismological centre isc catalogs that occurred in the zagros mountains during the period 1992 2002 and that were spanned by interferometric synthetic aperture radar insar images from the ers 1 and 2 satellites we invert the observed deformation for the best fitting point source single fault plane and distributed fault slip for four earthquakes and one unexplained deformation event we find that we can precisely locate earthquakes that are too small to be well located by either the hcmt or isc catalogs allowing us to tie specific earthquakes to active geologic structures

synthetic aperture radar interferometry to measure earth s surface topography and its deformation synthetic aperture radar interferometry insar from earth orbiting spacecraft provides a new tool to map global topography and deformation of the earth s surface radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter scale accuracy these data sets aid in the analysis and interpretation of tectonic and volcanic landscapes if the earth s surface deformed between two radar image acquisitions a map of the surface dis placement with tens of meters resolution and subcentimeter accuracy can be con structed this review gives a basic overview of insar for earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of insar for mapping the topography and deformation of the earth

seismic imaging of the western iberian crust using ambient noise boundaries and internal structure of the iberian massif abstract we present new rayleigh wave dispersion maps of the western iberian peninsula for periods between 8 and 30 s obtained from correlations of seismic ambient noise following the recent increase in seismic broadband network density in portugal and spain group velocities have been computed for each station pair using the empirical green s functions generated by cross correlating one day length seismic ambient noise records the resulting high path density allows us to obtain lateral variations of the group velocities as a function of period in cells of 0 5 0 5 with an unprecedented resolution as a result we were able to address some of the unknowns regarding the lithospheric structure beneath sw iberia the dispersion maps allow the imaging of the major structural units namely the iberian massif and the lusitanian and algarve meso cenozoic basins the cadiz gulf gibraltar strait area corresponds to a strong low velocity anomaly which can be followed to the largest period inverted although slightly shifted to the east at longer periods within the iberian massif second order perturbations in the group velocities are consistent with the transitions between tectonic units composing the massif

isotope stratigraphy of the ediacarian neoproterozoic iii of the adelaide rift complex australia and the overprint of water column stratification abstract this study establishes a high resolution 13c chemostratigraphic framework for the type ediacarian terminal proterozoic section in the adelaide rift complex a framework that contributes to the emerging global chronostratigraphic synthesis of a period that saw momentous changes in the earth s surface environment only 15 m of the 3 5 km thick type section consists of shallow water carbonates of the kind that have formed the basis of most previous studies of neoproterozoic chemostratigraphy however the organic 13corg record reveals a surprising richness of information and shows excellent utility in correlation between sections in the adelaide rift complex lateral variations in 13corg profiles correspond to expected diachronous patterns of basin fill with the addition of 87sr 86sr data correlation can also be made to the officer and amadeus basins consistent with known lithostratigraphic and sequence stratigraphic constraints sublittoral micritic carbonates of the upper nuccaleena formation cap dolostone and lower and middle wonoka formation show strong basinwide 13c depletion 13ccarb 3 to 10 despite compelling evidence for preservation of depositional 13ccarb such as good textural preservation evidence for sea floor lithification and in the wonoka formation pristine 87sr 86sr and low mn sr associated with the depleted carbonates are rare subaqueous evaporite relatively heavy 13corg and anomalously 13c depleted organic carbon of benthic microbial mat origin and a common cause salinity stratification of the water column is postulated the indicated palaeogeographic setting an evaporative mediterranean like basin tenuously connected to the world ocean is entirely consistent with previous suggestions of one or more messinian type desiccation events to explain very deep 1 km incised valleys or canyons in the adelaide rift complex and officer basin at horizons within the wonoka formation and correlates positive excursions in 13corg during basin stratification may in part be due to 12c depletion of surface waters by photosynthetic carbon fixation despite the proposed semi isolation of australian ediacarian basins from the world ocean major 13c excursions which can to some extent be differentiated by the monotonic rise in ediacarian marine 87sr 86sr appear to be correlatable to the upper windermere supergroup northwest canada

surface deformation associated with the mw 6 4 24 february 2004 al hoceima morocco earthquake deduced from insar implications for the active tectonics along north africa we study the surface deformation associated with the 24 february 2004 al hoceima earthquake mw 6 4 that recently affected the rif mountains of mo rocco the coseismic displacement field is mapped using synthetic aperture radar interferometry insar with the envisat esa satellite data acquired in the ascend ing and descending modes our analysis and modeling of insar data suggest that the earthquake is associated with a northwest southeast trending right lateral ap parently blind strike slip fault with a seismic moment reaching 6 8 10 18 n m this result is in contrast with the north northeast south southwest left lateral fault mech anism inferred from the modeling of seismic waves thrust and fold structures of the rif mountains developed during the tertiary period but the recent significant seismic events and late quaternary deformation indicate east west extension accom modated by north south trending normal and northwest southeast and northeast southwest trending conjugate strike slip faults the active deformation illustrates the fragmentation of the rif mountain range due to the africa iberia collision and west southwestward escape tectonics

the rupture process and location of the 2003 zemmouri boumerdes earthquake mw 6 8 inferred from seismic and geodetic data this work is a study of the earthquake mw 6 8 that occurred on may 21 2003 in zemmouri boumerdes algeria using methodology based on teleseismic data uplift measurements and synthetic aperture radar data as a starting point we fix the two source fault models obtained in this work solution 1 strike 64 dip 50 and rake 97 solution 2 strike 256 dip 40 and rake 91 with a length of 60 km and width of 20 km to calculate the slip distribution that best explains the seismic and geodetic observations the interferometric fringes revealed a strong displacement in the satellite direction 53 cm along the coast of algeria between the cities of boumerdes and zemmouri the inversion of teleseismic body waves for the two focal solution types one plane dipping to the se and the second plane dipping to the nw showed distinct ruptures however both bilateral ruptures included two asperities one near the hypocentre and the other at a shallower location the maximum slip solution 1 3 8 m and solution 2 4 0 m occurred near the hypocentre in both seismic source models the surface displacement model was obtained with okada s equations using the edcmp algorithm the three components of the displacements calculated were projected regarding the satellite direction los line of sight for comparison with the interferogram the geographic location of the fault plane was determined by comparing the uplift measurements with the vertical displacement models calculated with the source at several locations the surface displacements calculated from these source models indicate that the model based on the se plane and the epicentre location at 36 846 n and 3 660 e produces results closer to the interferogram and the uplift measurements

the tsunami induced by the 2003 zemmouri earthquake mw 6 9 algeria modelling and results summary a strong tsunami with sea disturbances observed along the algerian coast but with significant damage mainly in the balearic islands spain harbours affected the western mediterranean following the 2003 zemmouri earthquake m w 6 9 algeria an average regional uplift of 0 55 m was measured along the shoreline in the epicentral area field observations main shock and aftershocks characteristics are consistent with thrust along a 55 km long rupture trending ne sw dipping se the seismotectonic parameters indicate a hypocentre 7 8 km deep and a possible fault break between 5 and 15 km offshore several tide gauges located in the western mediterranean coast indicated an average of 0 4 m of sea level change with a maximum of 2 m in the balearic islands we generated high resolution bathymetry grids from the algerian coasts to the balearic islands coasts in order to test different seismic sources with different fault rupture location strike and dip and model the tsunami initiation and propagation for the modelling we employed the crank nicolson numerical schema with a finite difference method and the okada elastic dislocation theory for the fault rupture we also highlight the different factors responsible for waves amplification around the balearic coast the best fit between synthetic and real data tide gauges gps levelling and coastal uplift as compared to run up values are obtained for a thrust rupture comparable with the earthquake fault inferred from seismotectonic studies and located within 15 km offshore an analysis of t waves reinforces the earthquake rupture origin for the tsunami this study presents the results and modelling of a major tsunami recorded in the western mediterranean sea

complex tectonic and tectonostratigraphic evolution of an alpine foreland basin the western duero basin and the related tertiary depressions of the nw iberian peninsula abstract the tectonic and tectonostratigaphic evolution of foreland basins and related tertiary depressions are the key to investigate deformation history and the uplifting of the continental lithosphere of the alpine pyrenean orogeny the northern part of the duero basin is the foreland basin of the cantabrian mountains which are in turn the western part of the pyrenean orogen we have studied the western sharp end of the duero foreland basin and its relation to the tertiary deposits of the nw iberian peninsula and the topography evolution in order to propose a coherent tectonic and tectonosedimentary model that could explain all tertiary deposits we have analysed the depositional environment stratigraphic sequences paleocurrents and established a correlation of the main outcrops besides a detailed structural mapping of the alpine structures that limit and affect the main tertiary outcrops has been carried out the tertiary deposits of the nw iberian peninsula depressions are affected and fragmented by alpine structures that limit their extensions and locations the stratigraphic succession is similar in the nw tertiary outcrops they are mainly terrigenous and carbonated continental deposits formed by assemblage of alluvial fans developed at the mountains front in arid or semiarid conditions three formations can be identified in the main depressions toral fm santalla fm and medulas fm the nw tertiary outcrops were the western deposits of the duero foreland basin that surrounded the lateral termination of the pyrenean orogen these deposits were fragmented and eroded by the subsequent uplift of the galaico leoneses mountains and the ne sw strike slip faults activity broken foreland basin only the latest stages of some of these outcrops can be considered as intramontane basins as traditionally have been interpreted the sedimentation started in the northeast oviedo infiesto during the eocene and migrated to the west as pontes during the late oligocene early miocene times meanwhile southern areas were far away from the tectonic activity el bierzo o barco monforte sarria depressions

surface wave tomography from ambient seismic noise of accelerograph networks in southern korea 1 an efficient and robust cross correlation technique for estimation of surface wave green s function between two locations is applied to a set of ambient noise data recorded by accelerograph networks in the southern korea we have estimated 1843 group velocities of rayleigh waves in the period band of 2 4 seconds from correlation pairs of 91 accelerograph stations relatively dense and uniform coverage of the pairs provides us with high resolution tomographic image of surface wave group velocities in the region the resulting group velocity distribution correlates well with the characteristic features of geological map of the region displaying low velocities for the sedimentary basins and regions of volcanic and metasedimentary rocks and high velocities for the regions where granitoid basement rocks outcrop the short period information from the accelerograph network can enhance resolution of the subsurface structures at depths within a few kilometers which may be predominantly responsible for simulation results of strong ground motions

aseismic deformation of a fold and thrust belt imaged by synthetic aperture radar interferometry near shahdad southeast iran at depth many fold and thrust belts are composed of a gently dipping basal thrust fault and steeply dipping shallower splay faults that terminate beneath folds at the surface movement on these buried faults is difficult to observe but synthetic aperture radar sar interferometry has imaged slip on at least 600 km 2 of the shahdad basal thrust and splay fault network in southeast iran approximately 70 mm of thrust motion on the 88 dipping shahdad basal thrust occurred 8 30 km to the east of the 14 march 1998 fandoqa earthquake mw 5 6 6 that involved 1 6 m of oblique strike slip and normal slip displacement on a steeply dipping fault that earthquake transferred stress to the shahdad basal thrust and associated splays triggering slip either immediately or in the following six months modeling shows that to produce the observed surface deformation the shahdad faults must have accommodated a nearly complete release of the shear stress increase this could be due to either low friction on the faults or deformation throughout a wedge of material that is everywhere close to failure the anomalously small magnitude of displacement on the shahdad basal thrust and splay faults compared to the area of slip suggests a slip mechanism that is likely aseismic

inverting for slip on three dimensional fault surfaces using angular dislocations the increasing quality of geodetic data synthetic aperture radar interferometry insar dense global positioning system gps arrays now available to geophysicists and geologists are not fully exploited in slip inversion procedures most common methods of inversion use rectangular dislocation segments to model fault ruptures and therefore oversimplify fault geometries these geometric simplifications can lead to inconsistencies when inverting for slip on earthquake faults and they preclude a more complete understanding of the role of fault geometry in the earthquake process we have developed a new three dimensional slip inversion method based on the analytical solution for an angular dislocation in a linear elastic homogeneous isotropic half space the approach uses the boundary element code poly3d that employs a set of planar triangular elements of constant displacement discontinuity to model fault surfaces the use of triangulated surfaces as discontinuities permits one to construct fault models that better approximate curved three dimensional surfaces bounded by curved tiplines shapes that commonly are imaged by three dimensional reflection seismic data and inferred from relocated aftershock data we demonstrate the method s ability to model three dimensional rupture geometries by inverting for slip associated with the 1999 hector mine earthquake the resulting model avoids displacement anomalies associated with the overlapping rectangular dislocations used in previous models improving the fit to the geodetic data by 32 and honors the observed surface ruptures thereby allowing more direct comparisons between geologic and geodetic data on slip distributions online material hector mine input files and file format description

evidence for tear faulting from new constraints of the 23 october 2011 mw 7 1 van turkey earthquake based on insar gps coastal uplift and field observations

broadband ambient noise surface wave tomography across the united states 1 this study presents surface wave dispersion maps across the contiguous united states determined using seismic ambient noise two years of ambient noise data are used from march 2003 through february 2005 observed at 203 broadband seismic stations in the us southern canada and northern mexico cross correlations are computed between all station pairs to produce empirical green functions at most azimuths across the us coherent rayleigh wave signals exist in the empirical green functions implying that ambient noise in the frequency band of this study 5 100 s period is sufficiently isotropically distributed in azimuth to yield largely unbiased dispersion measurements rayleigh and love wave group and phase velocity curves are measured together with associated uncertainties determined from the temporal variability of the measurements a sufficient number of measurements 2000 is obtained between 8 and 25 s period for love waves and 8 and 70 s period for rayleigh waves to produce tomographic dispersion maps both phase and group velocity maps are presented in these period bands resolution is estimated to be better than 100 km across much of the us from 8 40 s period for rayleigh waves and 8 20 s period for love waves which is unprecedented in a study at this spatial scale at longer and shorter periods resolution degrades as the number of coherent signals diminishes the dispersion maps agree well with each other and with known geological and tectonic features and in addition provide new information about structures in the crust and uppermost mantle beneath much of the us

the tadjena earthquake mw 5 0 of december 16 2006 in the cheliff region northern algeria waveform modelling regional stresses and relation with the boukadir fault the cheliff region has experienced some significant earthquakes in the last century 1937 1954 and 1980 the most destructive one is that of el asnam on october 10 1980 ms 7 3 io ix which destroyed the chlef city formerly el asnam and its surrounding villages on december 16 2006 a moderate earthquake mw 5 0 hit the cheliff region the maximum observed intensity io v msk scale was observed at abou el hassen benaria bouzghaia and tadjena no damages or human losses were recorded nevertheless minor cracks on walls of the old school at tadjena were observed the point source focal mechanism of the event was determined by inverting the waveforms of three regional broadband stations of the adsn algerian digital seismic network it corresponds to thrust reverse faulting with a strike slip component the stress tensor obtained by the inversion of the 15 focal mechanisms available in the cheliff region exhibits a well constrained compression axis 1 horizontal and trending n145 the nw dipping nodal plane indicating a ne sw thrust fault with a right lateral component strike dip rake 249 38 137 is more compatible with the regional stress tensor than the steep dipping nne ssw nodal plane showing reverse faulting with a left lateral component strike dip rake 15 65 60 accordingly the tadjena moderate size earthquake can be related to the boukadir active fault bordering the lower cheliff basin to the north a situation similar to that of the el asnam fault bordering the middle cheliff basin to the north

reply to the comment of pedoja et al by maouche s meghraoui m morhange c belabbes s bouhadad y and haddoum h on the published paper maouche s meghraoui m morhange c belabbes s bouhadad y and haddoum h 2011 active coastal thrusting and folding and uplift rate of the sahel anticline and zemmouri earthquake area tell atlas algeria tectonophysics 509 2011 69 80 reply to the comment of pedoja et al by maouche s meghraoui m morhange c belabbes s bouhadad y and haddoum h on the published paper maouche s meghraoui m morhange c belabbes s bouhadad y and haddoum h 2011 active coastal thrusting and folding and uplift rate of the sahel anticline and zemmouri earthquake area tell atlas algeria tectonophysics 509 2011 69 80 said maouche mustapha meghraoui christophe morhange samir belabbes youcef bouhadad hamid haddoum

low velocity damaged structure of the san andreas fault at parkfield from fault zone trapped waves 1 we used dense linear seismic arrays across and along the san andreas fault saf at parkfield california to record fault zone trapped waves generated by explosions and microearthquakes in 2002 prominent trapped waves appeared at stations close to the saf main fault trace while some energy was trapped in the north strand at the array site observations and 3 d finite difference simulations of trapped waves at 2 5 hz show evidence of a damaged core zone on the main saf the zone from the surface to seismogenic depths is marked by a low velocity waveguide 150 m wide in which q is 10 50 and shear velocities are reduced by 30 40 from wall rock velocities with the greatest velocity reduction at shallow depth we interpret that this distinct low velocity zone on the main saf is a remanent of damage due to past large earthquakes on the principal fault plane at parkfield a less developed low velocity zone may be evident on the north strand that experienced minor breaks in the 1966 m6 event

coseismic deformation of the may 21st 2003 mw 6 8 boumerdes earthquake algeria from gps measurements 1 on may 21st 2003 a mw 6 8 earthquake struck the central part of northern algeria causing extensive damage in the boumerdes area 40 km east of algiers it is among the largest events to occur in the western mediterranean over the past 25 years we present gps measurements of horizontal coseismic displacements that provide new constraints on the rupture geometry modeling the data with a uniform dislocation on a rectangular fault in an elastic half space we find that the rupture occurred on a reverse fault dipping 42 s with its upper edge 6 km offshore and lower edge 4 km inland the amplitude distribution of the coseismic displacements indicates that the rupture did not reach the surface at least in its western part and ended to the west around 3 4 e offshore faults like that of the boumerdes earthquake could account for part of the africa eurasia relative plate motion in the western mediterranean and represent a significant seismic threat for algeria

geologic structures related to new madrid earthquakes near memphis tennessee based on gravity and magnetic interpretations new inversions of gravity and magnetic data in the region north of memphis tennessee and south of latitude 36 define boundaries of regional structures and igneous complexes in the upper crust microseismicity patterns near interpreted boundaries suggest that igneous complexes influence the locations of microseismicity a weak seismicity cluster occurs near one intrusion covington pluton at the intersection of the southwest margin of the missouri batholith and the southeast margin of the reelfoot rift a narrow seismicity trend along the reelfoot rift axis becomes diffuse near a second intrusion osceola intrusive complex and changes direction to an area along the northwest flank of the intrusion the axial seismicity trend also contains a tight cluster of earthquakes located just outside the osceola intrusive complex the mechanical explanation of the two seismicity patterns is uncertain but the first cluster may be caused by stress concentration due to the high elastic stiffness and strength of the covington intrusion the spatially changing seismicity pattern near the osceola complex may be caused by the preceding factors plus interaction with faulting along the rift axis the axial seismicity strand itself is one of several connected and interacting active strands that may produce stress concentrations at strand ends and junctions the microseismicity clusters at the peripheries of the two intrusions lead us to conclude that these stress concentrations or stressed volumes may be locations of future moderate to large earthquakes near memphis

full aftershock sequence of the m w 6 9 2003 boumerdes earthquake algeria space time distribution local tomography and seismotectonic implications we present a detailed analysis of the aftershocks of the may 21 2003 boumerdes earthquake m w 6 9 recorded by 35 seismological stations and 2 obs deployed in the epicentral area this network recorded the aftershock activity for about 1 year and resulted in locating about 2500 events the five main aftershocks 4 7 m 5 8 display thrust faulting consistent with the main shock except for the second event m5 8 29 05 2003 which depicts a strike slip focal solution at the western tip of the rupture zone most aftershocks are clustered near the main rupture plane in the footwall or at the westernmost tip of the 2003 boumerdes rupture area many aftershocks last over the whole seismic crisis ahead north of the main rupture zone forming a diffuse low angle surface within the footwall where the coseismic static stress change is predicted to increase at the sw tip of the rupture short lived clusters locate at intersections of faults near the contact between the inner kabylia and outer tell zones the tomographic inversion depicts high velocity p and s wave anomalies coinciding with miocene magmatic intrusive bodies in the upper crust partially hidden by surrounding basins the area of the main shock is associated with a large low velocity body subdivided into sub domains including neogene basins on land and offshore our results support a rupture model strongly controlled by geological inhomogeneities and extending as ramp flat ramp systems upward favoring heterogeneous slip and segmentation in the fault plane with strong afterslip toward the surface the diffuse aftershock activity in the footwall evidences an inherited discontinuity at mid crustal depth that we interpret as the contact of kabylian and african tethyan continental crusts that were stacked during the upper miocene collision

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

rayleigh wave group velocity tomography of the borborema province ne brazil from ambient seismic noise ambient seismic noise has traditionally been regarded as an unwanted perturbation that contaminates earthquake data over the last decade however it has been shown that consistent information about subsurface structure can be extracted from ambient seismic noise by cross correlation of noise simultaneously recorded at two seismic stations the empirical green s function for the propagating medium between them can be reconstructed moreover for periods less than 30 s the seismic spectrum of ambient noise is dominated by microseismic energy and because microseismic energy travels mostly as surface waves the reconstruction of the empirical green s function is usually proportional to the surface wave portion of the seismic wavefield in this paper we present 333 empirical green s functions obtained from stacked cross correlations of one month of vertical component ambient seismic noise for different pairs of seismic stations in the borborema province of ne brazil the empirical green s functions show that the signal obtained is dominated by rayleigh waves and that dispersion velocities can be measured reliably for periods between 5 and 20 s the study includes permanent stations from a monitoring seismic network and temporary stations from past passive experiments in the region resulting in a combined network of 34 stations separated by distances between approximately 40 and 1 287 km fundamental mode group velocities were obtained for all station pairs and then tomographically inverted to produce maps of group velocity variation for short periods 5 10 s the tomographic maps correlate well with surface geology with slow velocities delineating the main rift basins potiguar tucano and reconcavo and fast velocities delineating the location of the precambrian sao francisco craton and the rio grande do norte domain for longer periods 15 20 s most of the velocity anomalies fade away and only those associated with the deep tucano basin and the sao francisco craton remain the fading of the rio grande do norte domain fast velocity anomaly suggests this is a supracrustal structure rather than a lithospheric terrain and places new constraints on the precambrian evolution of the borborema province

coastal uplift and thrust faulting associated with the mw 6 8 zemmouri algeria earthquake of 21 may 2003 1 a shoreline uplift marked by a continuous white band visible at rocky headlands occurred during the 21 may 2003 earthquake mw 6 8 in northern algeria we measured the amount of coastal uplift on a white band emerged algae and harbors quays between boumerdes and dellys most of measured points were collected using tape and differential gps on rocky headlands with 0 15 m error bar tidal prism leveling lines running parallel and orthogonal to the coast also provide the precise amount of uplift in the epicentral area the uplift distribution shows an average 0 55 m along the shoreline with a maximum 0 75 m east of boumerdes and a minimum close to 0 near cap djinet the active deformation related to a thrust fault is modeled along the 55 km coastline the dislocation model predicts surface slip on a n 54 e trending reverse fault dipping 50 se in agreement with cmt solution and coastal uplift the faulting characteristics imply a fault geometry with possible sea bottom ruptures between 5 to 10 km offshore

surface wave tomography from microseisms in southern california received 5 april 2005 revised 23 may 2005 accepted 9 june 2005 published 26 july 2005 1 since it has already been demonstrated that point topoint seismic propagation green functions can be extracted from seismic noise it should be possible to image earth structure using the ambient noise field seismic noise data from 148 broadband seismic stations in southern california were used to extract the surface wave arrival times between all station pairs in the network the seismic data were then used in a simple but densely sampled tomographic procedure to estimate the surface wave velocity structure within the frequency range of 0 1 0 2 hz for a region in southern california the result compares favorably with previous estimates obtained using more conventional and elaborate inversion procedures this demonstrates that coherent noise field between station pairs can be used for seismic imaging purposes citation sabra k g p gerstoft p roux w a kuperman and m c fehler 2005 surface wave tomography from microseisms in southern california geophys res lett 32 l14311 doi 10 1029 2005gl023155

active coastal thrusting and folding and uplift rate of the sahel anticline and zemmouri earthquake area tell atlas algeria abstract major uplifts of late quaternary marine terraces are visible along the coastline of the tell atlas of algeria located along the africa eurasia convergent plate boundary the active tectonics of this region is associated with large shallow earthquakes m 6 5 numerous thrust mechanisms and surface fault related fold we conducted a detailed levelling survey of late pleistocene and holocene marine notches in the algiers region that experienced 0 50 m coastal uplift during the 2003 zemmouri earthquake mw 6 8 east of algiers holocene marine indicators show three pre 2003 main notch levels formed in the last 21 9 ka west of algiers on the sahel anticline the levelling of uplifted marine terraces shows a distinct staircase morphology with successive notches that document the incremental folding uplift during the late pleistocene and holocene the timing of successive uplifts related to past coseismic movements along this coastal region indicates episodic activity during the late holocene modelling of surface deformation in the zemmouri earthquake area implies a 50 km long 20 km wide ne sw trending se dipping fault rupture and an average 1 3 m coseismic slip at depth further west the 70 km long sahel fold is subdivided in 3 sub segments and shows 0 84 1 2 mm yr uplift rate in the last 120 140 ka the homogeneous holocene uplift of marine terraces and the anticline dimensions imply the possible occurrence of large earthquakes with mw 7 in the past the surface deformation and related successive uplifts are modelled to infer the size and characteristics of probable future earthquakes and their seismic hazard implications for the algiers region

high resolution biostratigraphic and chemostratigraphic data from the chenjiayuanzi section of the doushantuo formation in the yangtze gorges area south china implication for subdivision and global correlation of the ediacaran system intensive investigations on the doushantuo formation of south china have greatly advanced our understanding of the evolution of multicellular life and the atmospheric oceanic system during the ediacaran period particularly the well established carbon isotope profile and rich acritarch microfossils from the composite carbonate and shale successions of the yangtze gorges area provide potential for chronostratigraphic subdivision and global correlation of the ediacaran system here we present high resolution biostratigraphic and carbon isotope data from a well exposed section the chenjiayuanzi section in the yangtze gorges area the bio and chemostratigraphic data confirm the presence of three distinct negative and two positive 13c excursions and two characteristic assemblages of acanthomorphic acritarchs the lower tianzhushania spinosa assemblage and upper hocosphaeridium scaberfacium hocosphaeridium anozos tanarium conoideum tanarium anozos in liu et al 2013 assemblage within the doushantuo formation the results demonstrate the clear stratigraphic relationship between the acritarch assemblages and carbon isotope excursions of the doushantuo formation and that the last occurrence of acanthomorphic acritarchs in the chenjiayuanzi section represents the last occurrence datum found so far in the yangtze gorges of south china four stratigraphic markers are suggested here for defining chronostratigraphic boundaries of the ediacaran system based on bio and chemostratigraphy combined with intra and interbasinal correlation in particular the base of the most significant and distinctive carbon isotope excursion dounce at the top of the doushantuo formation which is equivalent to the shuram wonoka event elsewhere shows potential to be a marker to define the series lower and upper boundary of the ediacaran system because it also marks the extinction of the ediacaran acanthomorphic acritarchs

blind reverse faulting system associated with the mont chenoua tipaza earthquake of 29 october 1989 north central algeria a shallow and damaging earthquake struck the region of tipaza located on the coast 70 km to the west of algiers north central algeria the main shock was felt as far as 200 km from the epicentral area and particularly in the urbanized zone of algiers the main shock epicentre determined by craag is on mt chenoua close to the coastline coseismic surface breaks with 4 0 km of fault length and 7 0 cm of vertical displacement appeared on the southern side of mt chenoua they consist of cracks and fissures on vertical bedding planes that belong to a neogene flexure the aftershock activity was recorded for several weeks and comprised more than 100 seismic events per day with 1 m 5 aftershocks are distributed in a ene wsw to ne sw zone extending offshore a nw se cross section indicates that seismic events affect the crust to a maximum depth of 20 km showing a complex fault plane geometry dipping to the nw for the main shock the focal mechanism solution obtained from the readings of first motion polarities of seismograms yields an ene wsw reverse fault dipping to the nnw which is in good agreement with both field observations and the aftershock distribution at depth the occurrence of the mt chenoua tipaza moderate sized event in a previously identified active zone improves the seismotectonic characterization of this part of the tellan atlas mountains this thrust and fold geological domain also shows active folds capable of producing larger earthquakes since only a small portion of the sahel anticline ridge has been reactivated a serious seismic hazard must be urgently recognized in the algiers region

active thrust faulting offshore boumerdes algeria and its relations to the 2003 mw 6 9 earthquake 1 we investigate the active seismogenic fault system in the area of the 2003 mw 6 9 boumerdes earthquake algeria from a high resolution swath bathymetry and seismic survey a series of 5 main fault propagation folds 20 35 km long leave prominent cumulative escarpments on the steep slope and in the deep basin fault activity creates plio quaternary growth strata within uplifted areas such as a rollover basin on the slope and piggyback basins in the deep ocean most thrusts turn to fault propagation folds at the sub surface and depict ramp flat trajectories we find that the two main slip patches of the 2003 mw 6 9 boumerdes earthquake are spatially correlated to two segmented cumulative scarps recognized on the slope and at the foot of the margin the overall geometry indicates the predominance of back thrusts implying underthrusting of the neogene oceanic crust

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

fault geometry and earthquakes in continental interiors abstract although large earthquakes in continental interiors are much less frequent than those along plate boundaries they have been responsible for a disproportionate amount of destruction i present a testable model for strain accumulation and seismicity in the upper crust of continental interiors intersecting faults provide a focus for strain build up resulting in local pockets of high strain accumulation rigid plates typically deform at strain rates 10 10 to 10 9 strain yr 1 but at intersecting fault zones strain accumulates at anomalously high rates of 10 8 to 10 7 strain yr 1 i e the strain rates are comparable with those at plate boundaries the resulting large earthquakes are associated with relatively short return times hundreds of years typically one of the intersecting faults appears to split and to offset the other main fault defined as a fault on which the larger offset occurs forming two parallel strands separated by a jog i also observe a rotation of one leg of the main fault with respect to the other the region of intersection is usually associated with intense fracturing increased microseismicity and uplift

comment on zemmouri earthquake rupture zone mw 6 8 algeria aftershocks sequence relocation and 3d velocity model by a ayadi et al although often difficult to characterize the relationship between a seismic rupture its aftershock sequence and cumulative subsurface or surface faulting or folding is an important challenge to modern seismology and seismotectonics among other benefits it helps document fault length slip and magnitude relationships reconstruct the evolution of the rupture process through historical and prehistorical times and identify the complexity of the deformation in its path toward the surface this approach is a prerequisite to any seismic hazard assessment but is particularly difficult for faults whose surface trace projects offshore a specific effort to identify and quantify the source parameters of large earthquakes in coastal areas is therefore needed not only in subduction zones but also in areas of slow rate and or diffuse deformation

high resistant sand injected marl and low resistant damaged marl to locate and characterize the thenia fault zone in boumerdes city north central algeria the purpose of this study was to locate and characterize the thenia fault zone tfz in the urban area of boumerdes city geological and electrical resistivity tomography surveys have targeted the plaisancian marl and its quaternary cover as a whole data indicate a complex near vertical fault zone with an asymmetric and zoned internal structure of at least 150 m wide and with a straight n120 overall trending the fault zone is traversed with two elongated parallel fault branches fb1 and fb2 generally 70 m distant from each other these fault branches locate two intense damage zones idzs of 10 15 m thick each situated at the margin of two damage zones each having a thickness of several tens of meters downward sand injections into idzs during pleistocene epoch possible pulverization of plaisancian marl rocks systematic deflection of actual stream channels and vertical displacement of at least 30 m affecting quaternary alluvial deposits show that the area would have undergone active tectonic driven by the tfz

crustal transition between continental and oceanic domains along the north iberian margin from wide angle seismic and gravity data deep crustal features of the transition between the north iberian mainland and the bay of biscay are constrained from new wide angle seismic and gravity data velocity depth models are derived from far offset recordings onshore of two n s marine profiles complemented with new refraction data inland and tested against models that fit the gravity anomalies important lateral variations are inferred along the north iberian margin in the western transect a variscan crust is documented from the mainland across the continental shelf and a rapid crustal thinning beneath the slope marks the transition to the oceanic domain the eastern transect shows an outstanding crustal thickening beneath the coastline moho depths around 50 km and a gradual thinning across the shelf differences are related to the v shape of the bay of biscay that causes a w e transition along the margin from a short lived oceanic subduction to continental collision during the tertiary oblique convergence between europe and iberia

the recent upper miocene to quaternary and present tectonic stress distributions in the iberian peninsula a general synthesis of the recent and present stress situation and evolution in the iberian peninsula was obtained from microstructural and seismological analysis the stress evolution was deduced from 1 fault population analysis fpa from 409 sites distributed throughout the iberian peninsula 2 paleostress indicators given by 324 stations taken from the bibliography and 3 seismic data corresponding to 161 focal mechanisms evenly spread in the studied region the application of fpa together with the determination of stress tensors and focal mechanisms for the whole iberian microplate has provided two main results 1 the iberian peninsula is undergoing a nw se oriented compression except for the northeastern part pyrenees ebro basin and iberian chain where it is n s to ne sw and the gulf of cadiz where it seems to be e w and 2 the main trends of the stress field have remained almost constant since the upper miocene the analysis performed by zones suggests the presence of local heterogeneities in the stress field

the seismogenic zone of the continental crust in northwest iberia and its relation to crustal structure the distribution of seismicity at the western end of the cantabrian mountain range nw iberia reflecting current crustal dynamics is investigated integrating seismically active structures long term structures and the topographic features at the surface the thickness of the seismogenic zone within the continental crust is established in 20 km two crustal domains can be distinguished in the study area in terms of the seismicity pattern the style of alpine structures and the relief the presence of crustal fluids arises as a very likely contributing factor to the excessive thickness of the seismogenic zone in the study area more importantly a switch in tectonic style at the transition between crustal domains in coincidence with the lateral termination of orogenic frontal thrusts is envisaged as involving sufficient stress heterogeneity and amplification to explain the current concentration and characteristic pattern of historical seismicity in the region overall the distribution of seismicity in the crust is sensitive to the type and style of crustal structures

seismic signature of variscan and alpine tectonics in nw iberia crustal structure of the cantabrian mountains and duero basin the seismic structure of the crust of the nw iberian peninsula along the cantabrian mountains and their southern foreland the duero basin is investigated from the first data set available from refraction and wide angle reflection profiles the velocity depth distributions obtained along e w and n s transects evidence lateral variations in crustal structure that can be associated to variscan and alpine tectonic episodes the western part of the range toward the variscan hinterland zones as well as the duero basin below the sediments show a crustal structure similar to that of the variscan belt elsewere in europe the total crustal thickness is 30 32 km and three main layers upper middle and lower crust with average velocities 6 0 6 25 and 6 8 km s are resolved some paleozoic structures such as the basal detachment of the cantabrian zone are expressed in the seismic models the crust appears to vary eastward in the external zones the most outstanding feature is a crustal root beneath the highest cantabrian summits where the moho is found at 47 km depth a prominent alpine reworking of the crust in the eastern part of the cantabrian zone is thus revealed and the n s seismic transects delineate a geometry similar to the one found across the central pyrenees in the etude continentale et oceanique par reflexion et refraction sismique ecors profile revealing the importance of the alpine deformations in the northern part of the iberian plate

shallow afterslip following the 2003 may 21 mw 6 9 boumerdes earthquake algeria summary we investigated post seismic deformation following the 2003 may 21 mw 6 9 boumerdes algeria earthquake using surface displacements from six continuous global positioning system sites that operated in the epicentral area for 2 5 yr following the event we find up to 4 cm of cumulative horizontal displacement during that time period with a time dependence well fit by a logarithmic decay post seismic deformation appears to continue at all sites after the 2 5 yr observation period with rates on the order of 1 cm yr 1 or less the data is consistent with shallow afterslip 0 5 km and shows no evidence for afterslip downdip of the coseismic rupture the data is poorly explained by viscoelastic relaxation in the lower crust or upper mantle or by poroelastic rebound the concentration of afterslip adjacent to and updip of the coseismic rupture at least in the western half of the fault suggests that afterslip is driven by coseismic stresses the correlation between the depth of afterslip and that of the sedimentary wedge along the algerian margin while coseismic slip occurs in deeper basement rocks suggests 1 that post seismic deformation may also involve folding and 2 that spatial variations in frictional properties along the fault correlate with the type of rocks involved

proliferation of miss forming microbial mats after the late neoproterozoic glaciations evidence from the kimberley region nw australia abstract a total of 20 morphological types of microbially induced sedimentary structures miss are recognized from the late neoproterozoic tillite bearing successions of the kimberley northwestern australia which include alpha petees triradiate cracks multidirectional linear ridges millimeter ripples erosional remnants and pockets and so on of these triradiate cracks multidirectional linear ridges and millimeter ripples are reported for the first time from the neoproterozoic worldwide most kimberley miss are morphologically comparable with their ancient and present day counterparts whose biogenicity have been well demonstrated in the kimberley during the interglacial period miss have colonization preference to relatively coarse sandy substrates ranford formation and their abundance decreased towards the younger strata throssell shale in contrast miss abundance increased from the older strata yurabi formation towards the younger strata flat rock formation during the postglacial period however overall both miss abundance and bedding plane coverage percentage increased from the marinoan younger marinoan gaskiers interglacial successions to younger marinoan gaskiers postglacial successions indicating a proliferation of microbial mats after the younger marinoan gaskiers glaciation the increase of microbial mats could have ameliorated marine biogeochemical conditions and ecosystems and thus laid the foundation for the rise of ediacaran biota in australian basins