inversion of complex body waves we have developed a method that inverts seismic body waves to determine the mechanism and rupture pattern of earthquakes the rupture pattern is represented as a sequence of subevents distributed on the fault plane this method is an extension of our earlier method in which the subevent mechanisms were fixed in the new method the subevent mechanisms are determined from the data and are allowed to vary during the sequence when subevent mechanisms are allowed to vary however the inversion often becomes unstable because of the complex trade offs between the mechanism the timing and the location of the subevents many different subevent sequences can explain the same data equally well and it is important to determine the range of allowable solutions some constraints must be imposed on the solution to stabilize the inversion we have developed a procedure to explore the range of allowable solutions and appropriate constraints in this procedure a network of grid points is constructed on the i plane where and i are respectively the onset time and the distance from the epicenter of a subevent the best fit subevent is determined at all grid points then the correlation is computed between the synthetic waveform for each subevent and the observed waveform the correlation as a function of and i and the best fit mechanisms computed at each i grid point depict the character of allowable solutions and facilitate a decision on the appropriate constraints to be imposed on the solution the method is illustrated using the data for the 1976 guatemala earthquake

nucleation linkage and active propagation of a segmented quaternary normal dextral fault the loma del viento fault campo de dalias eastern betic cordillera se spain active faults from the campo de dalias se betic cordillera allow us to constrain the deformation styles involved in the development of segmented oblique slip faults this sector constitutes the widest outcrop of plio quaternary sediments in the northern boundary of the alboran sea it has emerged since the late pliocene and therefore provides recent deformation markers that are not disturbed by erosive processes the faults started to grow during the pleistocene reactivating previous hybrid joints with a normal dextral slip we present a detailed map of the largest fault in the area the loma del viento fault comprising six onshore segments based on field work and aerial photography the distributions of the contiguous joints have been mapped and the joints reactivated as faults are identified some of these fault segments are hard linked and fault slip enhances toward the linkage sectors between them with associated sedimentary depocenters an electrical tomography profile reveals the wedge geometry of a unit of pleistocene conglomerates and red silts that were coevally deposited during the fault movement long term slip rate in the central part of the fault is estimated at 0 07 0 03 mm y in addition a seismic crisis nucleated close to the loma del viento fault during november 2010 was recorded moment tensor analysis of the two mainshocks mw 3 5 and 4 2 provides a focal solution indicating a n120 e striking right lateral strike slip fault the corrugated morphology of the loma del viento fault may have influenced its seismic behavior some of the fault segments are oblique to the general motion of the fault these oblique segments would provide higher resistance against the general fault motion and could lock the fault leading to accumulate elastic energy

seismicity and active tectonics in the alboran sea western mediterranean constraints from an offshore onshore seismological network and swath bathymetry data seismicity and tectonic structure of the alboran sea were derived from a large amphibious seismological network deployed in the offshore basins and onshore in spain and morocco an area where the convergence between the african and eurasian plates causes distributed deformation crustal structure derived from local earthquake data suggests that the alboran sea is underlain by thinned continental crust with a mean thickness of about 20 km during the 5 months of offshore network operation a total of 229 local earthquakes were located within the alboran sea and neighboring areas earthquakes were generally crustal events and in the offshore domain most of them occurred at crustal levels of 2 to 15 km depth earthquakes in the alboran sea are poorly related to large scale tectonic features and form a 20 to 40 km wide nne ssw trending belt of seismicity between adra spain and al hoceima morocco supporting the case for a major left lateral shear zone across the alboran sea such a shear zone is in accord with high resolution bathymetric data and seismic reflection imaging indicating a number of small active fault zones some of which offset the seafloor rather than supporting a well defined discrete plate boundary fault moreover a number of large faults known to be active as evidenced from bathymetry seismic reflection and paleoseismic data such as the yusuf and carboneras faults were seismically inactive earthquakes below the western alboran basin occurred at 70 to 110 km depth and hence reflected intermediate depth seismicity related to subducted lithosphere

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

source parameters of the mw 6 1 1910 adra earthquake southern spain summary we examine and model analogue recordings from 6 early mechanical seismographs for the 1910 june 16 earthquake at adra southern spain modern standard time domain analysis techniques were applied to the historical data to estimate the source parameters of the event the regional sparse network data were inverted for the deviatoric seismic moment tensor the best moment tensor solution corresponds to a m0 1 50 1018 nm mw 6 1 oblique strike slip event at 16 km depth our preferred faulting solution is strike 122 dip 80 rake 137 in very good agreement with available neo and seismotectonic data the source time function of this earthquake was estimated by deconvolving recordings of a mw 5 5 aftershock that occurred the same day the time function indicates a total rupture time of 4 5 s corresponding to estimates for mainshock rupture length of 12 km and stress drop of 29 bar

3 d geologic modeling in the flin flon mining district trans hudson orogen canada evidence for polyphase imbrication of the flin flon 777 callinan volcanogenic massive sulfide ore system three dimensional geologic modeling by integrated analysis and interpretation of drill core 2 d and 3 d seismic mine survey and geologic map data provides new insights into the structural setting of the 85 5 million tonne mt flin flon callinan 777 volcanogenic massive sulfide vms ore system hosted in the paleoproterozoic flin flon belt of manitoba and saskatchewan canada the resultant camp scale 3 d geologic model was in addition to the densely drill intersected vms hosting mine horizon constrained by lithostratigraphic reference drill holes intersecting the footwall and hanging wall rock successions of the ore system which were established by relogging 52 drill holes and systematically reconciling the lithofacies classes in their log descriptions with the lithofacies units of the 1 10 000 scale flin flon mining district geologic map the lateral persistence and large stratigraphic range of these drill hole markers supported seismic interpretation and allowed tracing lithostratigraphic horizons and structures in areas with low drill hole density expanding 3 d subsurface insight from the local to the more regional structural setting of the ore system the overall 3 d modeled geometry and topological relationships between lithostratigraphic surfaces and multiple generations of thrust faults suggest that the flin flon mining district is underlain by an e dipping stack of w vergent thrust imbricates that formed during precollisional and collisional stages of the 1 9 to 1 8 ga trans hudson orogeny the imbricate stack was subsequently deformed by e trending ductile thrust faults that internally imbricated the flin flon arc assemblage and the molasse cover rocks of the missi group and brought up rocks of the former over the latter in a northerly direction the vms hosting millrock member has been stacked on at least four structural levels enhancing the vms potential in the footwall and hanging wall of the known ore deposits where both thrust systems intersect

source parameters for small events associated with the 1986 north palm springs california earthquake determined using empirical green functions using small events as empirical green functions which include path site and instrument effects on the p waveforms source parameters were estimated for 25 ml 3 4 to 4 4 events associated with the 1986 north palm springs earthquake the static stress drops ranged from 3 to 80 bars for moments of 0 7 to 11 1021 dyne cm there was a spatial pattern to the stress drops of the aftershocks which showed increasing values along the fault plane toward the northwest compared to relatively low values near the hypocenter of the mainshock the highest values were outside the main area of slip and are believed to reflect a loaded area of the fault that still has an higher level of stress which was not released during the main shock the relatively high stress drop of a preshock in 1983 located close to the hypocenter of the main shock is also interpreted as evidence that stress drops of magnitude 3 and 4 events can be used as indicators of the stress level in a particular area

mechanism of the 1992 erzincan earthquake and its aftershocks tectonics of the erzincan basin and decoupling on the north anatolian fault summary the 1992 march 13 erzincan earthquake ms 6 8 affected the erzincan basin on the eastern part of the north anatolian fault naf this event occurred on the eastern tip of a westward propagating series of major north anatolian earthquakes between 1939 and 1967 ambraseys 1970 it is located within a key region of eastern anatolia which displays both expulsion of the anatolian block towards the west and regional n s convergence due to the arabian eurasian collision philip et al 1989 a reinterpretation of the tectonics of the erzincan basin is made from field information and the analysis of satellite images a model explaining the development of the basin is proposed it combines a pull apart on the naf with the effect of two compressional wedges one is formed by the northeast anatolian fault neaf and the naf the other around pulumur is limited by the ovacik fault of and the naf both e w extension and n s compression occur according to this model normal faulting on the southwestern border and extension related quaternary rhyolitic volcanic domes along the northeastern boundary of the basin support the proposed e w extension the block limiting the southern side of the basin is uplifted and displaced left laterally along the of suggesting southward growth of the basin a kinematic model of the 1992 erzincan earthquake combines aftershock field information neotectonic observations satellite image interpretation and bodywaveform inversion the complex earthquake rupture starts on the naf and propagates bilaterally westward rupture propagation progresses along the northern border of the basin eastward propagation is shifted on a segment of the naf south of the euphrates and ends within the pulumur wedge both branches are connected by a system of normal faults the main focal mechanism is strike slip with a slight normal component o 122 63 164 the strongest aftershock mechanism is compatible with n s compression within the pulumur wedge aftershock mechanisms and stress tensor analyses give detailed insight into the earthquake sequence the 1992 erzincan earthquake is located between two segments of the naf that suffered large destructive earthquakes in the past the 1939 earthquake ms 8 2 ruptured 370 km west of erzincan the last major earthquake east of the erzincan basin occurred in 1784 rupturing a segment of at least 75 km length this area has displayed a seismic gap since then the mechanism of the main shock and the absence of aftershock activity east of tanyeri indicate decoupling between the 1992 event and the 1784 gap aftershocks within the pulumur wedge suggest that the probability of the occurrence of a future earthquake is higher on the of than in the 1784 earthquake gap

geodynamic evolution of the lithosphere and upper mantle beneath the alboran region of the western mediterranean constraints from travel time tomography an edited version of this paper was published by the american geophysical union copyright 2000 agu see also http www agu org pubs crossref 2000 2000jb900024 shtml http atlas geo cornell edu morocco publications calvert2000 htm

vertical ground motion in southern spain we quantify the attenuation of ground motion with distance in south ern spain using 6052 velocity recordings from 1107 local and regional earthquakes registered by the andalusianvertical component short period network epicentral dis tances and magnitudes range from 3 to 500 km and from 1 0 to 5 1 respectively the observed peak velocity and the root mean square rms fourier velocity amplitudes with distance are parameterized by excitation distance and site terms for a set of fre quencies ranging from 1 to 12 hz we obtain these terms by performing an iterative damped least squares regression from the excitation term we extract its scaling law with magnitude by using brune s source model the distance terms are fitted by ana lytic functions that depend on geometrical spreading coefficients and a frequency dependent attenuation parameter apart from the analysis of the entire data set we perform two separate analyses of two subdata sets offshore earthquakes alboran data set and inland earthquakes betic data set these data sets have differences in their probed earth structures showing distance terms clearly distinct with higher attenuation in the alboran area q0 100 compared to the betic area q0 200 random vibration theory proved to be a suitable tool to simulate observed peak am plitudes from the obtained spectral scaling laws and signal durations

moment tensor inversion with single component historical seismograms the 1909 benavente portugal and lambesc france earthquakes summary moment tensor inversion of early xx century mechanical seismograph recordings offers the opportunity to estimate source parameters for a number of important earthquakes this knowledge is crucial for understanding regional tectonics and estimating seismic hazard but processing of the historical seismograms is often difficult especially the rotation of horizontal seismograms into radial p sv and transverse sh components tends to fail for example if one polarity is wrong if the alignment of the seismograms is not correct or if one component is lost to avoid these kind of problems we use a moment tensor inversion scheme that processes the original single component horizontal traces without rotation and rotates the theoretical green s functions instead we show how this approach simplifies the analysis and allows a better use of available data we present moment tensor solutions for two destructive earthquakes in southwestern europe in 1909 the april 23 earthquake near benavente in the lower tagus valley portugal had a moment magnitude mw 6 0 and an estimated centroid depth of 10 km our preferred moment tensor solution indicates reverse faulting nodal planes have strike dip rake of n51 e 52 83 and n242 e 38 99 we propose a blind thrust beneath the tagus valley sediment basin as the responsible fault the june 11 earthquake near lambesc provence france was found to be slightly smaller mw 5 5 and related to oblique reverse faulting at 4 km depth nodal planes of the preferred solution have strike dip rake of n80 e 53 53 and n311 e 50 128 subparallel to the trevaresse fold

lateral variation of the crust in the iberian peninsula new evidence from the betic cordillera abstract new results from a seismic refraction wide angle reflection survey carried out in the betic cordillera in autumn 1989 contribute to a better picture of its deep structure one nw se profile cuts across the iberian massif the external and internal betics the structure of the crust in the iberian massif shows characteristics similar to those found in previous experiments the lower crust is found as a distinct layer 12 km thick with an average velocity of 6 8 km s 1 the moho is found at about 35 km depth this structure extends southeastward until a 3 4 km upwelling of the moho about 30 km north of the present day surface boundary between the external and internal betic units further southeast the moho deepens to 38 km and the lower crust is no longer seismically detected the absence of differentiated lower crust beneath part of the external betics may be related with the mesozoic rifting of the south iberian passive margin instead this absence under the internal betics may be caused by rifting in conjunction with the collisional evolution of the orogen a wnw ese profile lying in the internal betics shows the presence of a prominent reflector at 10 12 km depth this seems to be a widespread feature in the internal betics and may be interpreted as a detachment surface the moho is found at 38 km depth rising strongly in the easternmost betics seismic data suggest a thin crust in the offshore area southwest of malaga probably containing a massive zone of high velocity rocks which is also supported by available geophysical and geological data

efficient calculation of complete differential seismograms for laterally homogeneous earth models summary differential seismograms the sensitivity of the seismogram to perturbations of parameters of the earth model are essential for waveform modelling with iterative non linear optimization techniques the growing number of broad band highdynamic range fixed and portable stations provide a rich data set of regional distance events with accurate locations and source mechanisms that are ideal for modelling lithospheric structure an efficient technique for calculating differential seismograms for complete synthetic seismograms in laterally homogeneous earth models will significantly decrease the computational burden of seismic waveform inverse modelling the technique we present here is equivalent to computing three synthetic seismograms in multilayered models contrasted with n 1 seismograms for a typical brute force approach which reduces the work to 3 n 1 or about a 90 per cent saving for 30 layers the lateral homogeneity requirement will yield path averaged structures which may form the basis for later tomographic studies to resolve lateral variations

point source inversion techniques abstract a variety of approaches for obtaining source parameters from waveform data using moment tensor or dislocation point source models have been investigated and applied to long period body and surface waves from several earthquakes generalized inversion techniques have been applied to data for long period teleseismic body waves to obtain the orientation time function and depth of the 1978 thessaloniki greece event of the 1971 san fernando event and of several events associated with the 1963 induced seismicity sequence at kariba africa the generalized inversion technique and a systematic grid testing technique have also been used to place meaningful constraints on mechanisms determined from very sparse data sets a single station with high quality three component waveform data is often sufficient to discriminate faulting type e g strike slip etc sparse data sets for several recent california earthquakes for a small regional event associated with the koyna india reservoir and for several events at the kariba reservoir have been investigated in this way although linearized inversion techniques using the moment tensor model are often robust even for sparse data sets there are instances where the simplifying assumption of a single point source is inadequate to model the data successfully numerical experiments utilizing synthetic data and actual data for the 1971 san fernando earthquake graphically demonstrate that severe problems may be encountered if source finiteness effects are ignored these techniques are generally applicable to on line processing of high quality digital data but source complexity and inadequacy of the assumed green s functions are major problems which are yet to be fully addressed

lateral variations of the local magnitude at ebre station northeastern iberian peninsula since 1984 a seismic surveillance at the baix ebre region ne of the iberian peninsula has been carried out from a seismic network consisting of two digital and one analog stations large discrepancies between the recorded amplitudes and the magnitude estimates given by different agencies have been observed to explain these discrepancies that consist of a large reduction of amplitude and a strong dependence of the azimuth a local magnitude formula for the area has been computed using the analog records obtained at ebr short period station global results show an average station correction factor between the computed local magnitude and the reported magnitude of the order of 1 presenting large variations around the mean value with a clear dependence on the azimuth a detailed analysis of this variation around the mean value reveals that earthquakes can be classified according to their location in different geological units thus obtaining for each zone a distinct station correction factor that can fluctuate as much as 0 6 around the average these large lateral variations of the magnitude are in good agreement with previous studies of coda q attenuation

geomorphic evidence of active tectonics in the sierra alhamilla eastern betics se spain abstract active tectonic deformation influencing the streams and hillslopes of the sierra alhamilla ridge anticlinorium in southeast spain is related to the dextral reverse polopos fault zone to the north and east of the ridge and to normal faulting in the southern side of the ridge a fault segmentation and fluvial terrace mapping is presented in this paper the following geomorphic indices were calculated in the area the mountain front sinuosity valley floor width to height ratio drainage basin asymmetry factor basin hypsometric curve and integral longitudinal river profile and stream length gradient index normalized by the graded river gradient slk index the slk map shows two sets of high anomalies a an e w striking anomaly due to the dextral reverse polopos fault zone located in the northern limb of the anticlinorium b a group of nnw sse striking anomalies associated with pliocene quaternary nw se to nnw sse striking high angle normal faults that cut the southern limb late pleistocene holocene activity occurred along the north alhamilla reverse fault and the dextral transpressive south gafarillos fault two segments in the polopos fault zone the former fault produces rejuvenation of the streams at the base of the northern slope in this area mountain front sinuosity and valley floor width to height ratio suggest quaternary uplift rates between 0 05 and 0 5 m ky 1 holocene to present day activity of the south gafarillos fault is demonstrated by faulted late pleistocene terraces and holocene colluvial deposits and suggested by deflected streams that have complex or convex hypsometric curves pliocene quaternary high angle normal faults control the relief in the southern limb and the western end of the sierra alhamilla these faults produce low mountain front sinuosity and valley floor width to height ratio indices typical of uplift rates quite higher than field based rates from some other studies

geodetic evidence for continuing tectonic activity of the carboneras fault se spain abstract the carboneras fault zone cfz is a prominent onshore offshore strike slip fault that forms part of the eastern betic shear zone ebsz located in se spain in this work we show for the first time the continuing tectonic activity of the cfz and quantify its geodetic slip rates using continuous and campaign gps observations conducted during the last decade we find that the left lateral motion dominates the kinematics of the cfz with a strike slip rate of 1 3 0 2 mm yr along the n48 direction the shortening component is significantly lower and poorly constrained recent onshore and offshore paleoseismic and geomorphic results across the cfz suggest a minimum late pleistocene to present day strike slip rate of 1 1 mm yr considering the similarity of the geologic and geodetic slip rates measured at different points along the fault the northern segment of the cfz must have been slipping approximately at a constant rate during the quaternary regarding the eastern alpujarras fault zone corridor afz located to the north of the cfz our gps measurements corroborate that this zone is active and exhibits a right lateral motion these opposite type strike slip motion across the afz and cfz is a result of a push type force due to nubia and eurasia plate convergence which in turn causes the westward escape of the block bounded by these two fault zones

active faulting offshore se spain alboran sea implications for earthquake hazard assessment in the southern iberian margin the southern margin of the iberian peninsula hosts the convergent boundary between the european and african plates the area is characterised by low to moderate magnitude shallow earthquakes although large historical events have also occurred in order to determine the possible sources of these events we recently acquired swath bathymetry tobi sidescan sonar and high resolution seismic data on the almeria margin eastern alboran sea the new dataset reveals the offshore continuation of the ne sw trending carboneras fault a master fault in the eastern betic shear zone and its associated structures n150 and ns faults these structures are active since they cut the late quaternary sedimentary units the submarine carboneras fault zone is 100 km long 5 10 km wide and is divided into two n045 and n060 segments separated by an underlapping restraining stepover geomorphic features typically found in subaerial strike slip faults such as deflected drainage water gaps shutter ridges pressure ridges and ben echelonq folds suggest a strike slip motion combined with a vertical component along the submarine carboneras fault considering the nnw sse regional shortening axis a left lateral movement is deduced for the carboneras fault whereas right lateral and normal components are suggested for the associated n150 and ns faults respectively the offshore portion of this fault is at least twice as long as its onshore portion and together they constitute one of the longest structures in the southeastern iberian margin despite the fact that present day seismicity in the almeria margin seems to be associated with the n150 to ns faults the carboneras fault is a potential source of large magnitude mw 7 2 events hence the carboneras fault zone could pose a

the 1951 mw 5 2 and mw 5 3 jaen southern spain earthquake doublet revisited we collected analog seismogram recordings and seismic bulletins for two moderate magnitude earthquakes in the province of jaen southern spain on 10 march and 19 may 1951 and the series of aftershocks seismograms from the two main events reveal striking similarity pointing to nearby locations and similar source mechanisms this casts a shadow on the quality of preserved phase readings and macroseismic data which suggests a distance of several tens of kilometers between both mainshocks and aftershocks a critical review of available phase readings permitted us to detect several misinterpretations in the original bulletins and to obtain better constrained hypocenter relocations about 10 km apart for the two mainshocks as well as location estimates for 20 aftershocks the recording of the 1951 jaen earthquake doublet at a network of common stations allows a straightforward quality control of our digitized seismograms by waveform comparison we estimate faulting parameters of the two mainshocks from regional moment tensor inversion obtaining moment magnitude m w 5 2 and m w 5 3 respectively depth of 20 km and strike slip faulting mechanisms with minor normal slip component and northeast southwest oriented t axes deconvolution of body waveforms from an m w 4 4 aftershock yields simple triangular source time functions for both main events with durations close to 1 sec while several previous studies had difficulties in characterizing these earthquakes partially describing them as unusual intermediate deep focus events we propose simple shear faulting sources in the middle crust and faulting geometries consistent with the regional seismotectonic framework

source analysis of the mw 6 3 2004 al hoceima earthquake morocco using regional apparent source time functions 1 we use small and moderate aftershocks of the 24 february 2004 al hoceima earthquake as empirical greens functions egfs to retrieve the rupture history of the main event the magnitude depth and geometry of faulting were estimated for the main shock and 20 small and moderate aftershocks mw between 3 9 and 5 2 computing moment tensor solutions for the main shock we obtain a moment magnitude of mw 6 3 and a nearly pure double couple source 4 compensated linear vector dipole with predominately strike slip faulting the preferred fault plane has a strike of n11 e a dip of 72 and a rake of 17 fourteen aftershocks having depths 4 km and faulting geometries 11 for the strike of the preferred plane similar to the ones found for the main event were used as egfs apparent source time functions astfs of the al hoceima event were retrieved at twelve regional stations using an iterative time domain deconvolution on the p waveforms at each station time functions are enhanced by stacking of the deconvolved waveforms for different egfs astfs show total durations of 5 to 6 s two consecutive subevents separated by about 3 s and only a weak effect of directivity we further investigate the source history by inverting the set of astfs for the distribution of fault slip and rupture propagation two different source models were selected for presentation one involving one single fault plane and the other involving two parallel fault planes the two fault model fits more accurately the observations and leads to a more plausible slip distribution we estimate rupture dimensions of about 10 10 km2 and 8 8 km2 and moment magnitudes of mw 6 2 and 6 0 for the first and second subevent respectively

seismostratigraphy and tectonic architecture of the carboneras fault offshore based on multiscale seismic imaging implications for the neogene evolution of the ne alboran sea in the se iberian margin which hosts the convergent boundary between the european and african plates quaternary faulting activity is dominated by a large left lateral strike slip system referred to as the eastern betic shear zone this active fault system runs along more than 450 km and it is characterised by low to moderate magnitude shallow earthquakes although large historical events have also occurred the carboneras fault is the longest structure of the eastern betic shear zone and its southern termination extends further into the alboran sea previously acquired high resolution data i e swath bathymetry tobi sidescan sonar and sub bottom profiler show that the offshore carboneras fault is a ne sw trending upwarped zone of deformation with a length of 90 km long and a width of 0 5 to 2 km which shows geomorphic features typically found in subaerial strike slip faults such as deflected drainage pressure ridges and en echelon folds however the neotectonic depth architecture and neogene evolution of carboneras fault offshore are still poorly known in this work we present a multiscale seismic imaging of the carboneras fault i e topas high resolution multichannel seismic reflection and deep penetration multichannel seismic reflection carried out during three successive marine cruises from 2006 to 2010 the new dataset allowed us to define a total of seven seismostratigraphic units from tortonian to late quaternary above the basement to characterise the tectonic architecture and structural segmentation of the carboneras fault and to estimate its maximum seismic potential we finally discuss the role of the basement in the present day tectonic evolution of the carboneras fault and explore the northern and southern terminations of the fault and how the strain is transferred to nearby structures

active continental subduction beneath the betic cordillera and the alboran sea p and s wave seismic tomography detect a low velocity anomaly in the upper mantle beneath the betic cordillera and the alboran sea region the anomaly is associated with the intermediate depth seismicity h

constraining pre instrumental earthquake parameters from slope stability back analysis palaeoseismic reconstruction of the guevejar landslide during the 1st november 1755 lisbon and 25th december 1884 arenas del rey earthquakes abstract slope stability back analysis performed for landslides known to have been triggered by an earthquake can provide additional constraints on the size and location of pre instrumental seismic events this paper reconstructs the pre earthquake conditions of a major landslide located in the granada basin the guevejar landslide which was triggered twice by the 1755 lisbon and 1884 arenas del rey earthquakes for each case the minimum seismic acceleration needed to trigger the instability has been calculated and from this datum the most likely magnitude and epicentral location have been inferred for each event the results suggest that the moment magnitude of the 1755 lisbon earthquake was at least 8 5 and that it was located as far as 580 km from the landslide for the 1884 arenas del rey earthquake the moment magnitude was at least 6 5 and it was located within 55 km of guevejar these results indicate the ventas de zafarraya fault as the seismogenic source of the event apart from these two major events other significant historical earthquakes which took place in the granada basin are also analysed in the paper it is confirmed that none of these was able to reactivate the landslide not even the 1806 pinos puente earthquake the guevejar landslide is stable under present day conditions but it could be reactivated by an earthquake as small as m w 4 7 directly at the site

non double couple earthquakes 1 theory historically most quantitative seismological analyses have been based on the assumption that earth quakes are caused by shear faulting for which the equiv alent force system in an isotropic medium is a pair of force couples with no net torque a double couple or dc observations of increasing quality and coverage however now resolve departures from the dc model for many earthquakes and find some earthquakes especially in volcanic and geothermal areas that have strongly non dc mechanisms understanding non dc earth quakes is important both for studying the process of faulting in detail and for identifying nonshear faulting processes that apparently occur in some earthquakes this paper summarizes the theory of moment tensor expansions of equivalent force systems and analyzes many possible physical non dc earthquake processes contrary to long standing assumption sources within the earth can sometimes have net force and torque components described by first rank and asymmetric sec ond rank moment tensors which must be included in analyses of landslides and some volcanic phenomena non dc processes that lead to conventional symmetric second rank moment tensors include geometrically complex shear faulting tensile faulting shear faulting in an anisotropic medium shear faulting in a heteroge neous region e g near an interface and polymorphic phase transformations undoubtedly many non dc earthquake processes remain to be discovered progress will be facilitated by experimental studies that use wave amplitudes amplitude ratios and complete waveforms in addition to wave polarities and thus avoid arbitrary assumptions such as the absence of volume changes or the temporal similarity of different moment tensor com ponents

evidence for active subduction beneath gibraltar we report on a marine seismic survey that images an active accretionary wedge west of gibraltar ramp thrusts offset the seafloor and sole out to an east dipping decollement indicating ongoing westward vergent tectonic shortening new traveltime tomographic re sults image a slab of oceanic lithosphere descending from the atlantic domain of the gulf of cadiz passing through intermediate depth 60 120 km seismicity beneath the west ernmost alboran sea and merging with a region of deep focus earthquakes 600 660 km below granada spain together these new data provide compelling evidence for an active east dipping subduction zone

comparing seismic parameters for different source zone models in the iberian peninsula abstract seismical parameters of five seismogenic zonings for the iberian peninsula have been determined in this work for that purpose this research has two key goals the first is to generate a seismic catalog the second to calculate the seismical parameters of all the zones of the seismogenic zonings selected the first key goal has been the creation of a catalog of earthquakes for the iberian peninsula and adjacent areas first the national geographic institute of spain s catalog has been completed and reviewed with the information from other catalog reviews and specific studies second all magnitude calculations have been homogenized third all dependent data have been eliminated through declustering finally the year of completeness for each magnitude has been considered the quaternary active faults database of iberia has also been used as input data all of this information has been integrated into a geographic information system the second key aim is the calculation of the seismical parameters the first parameter obtained has been the b value a method which considers different years of completeness in accordance with the magnitude has been used also the annual rate of earthquakes per square kilometer has been calculated moreover the maximum magnitude known that quaternary active faults might generate and maximum magnitude recorded in the catalog have been determined finally based solely on the statistical parameters obtained a critical discussion of the seismogenic zonings of the iberian peninsula has been conducted the results show that some zonings possess insufficient data for a proper calculation of the seismic parameters from a statistical point of view

seismological evidence for a delamination process in the lithosphere under the alboran sea summary the continental collision between the african and eurasian plates in the iberian peninsula is solved with a nw se compression with an extensional basin the alboran sea to explain this paradox several models have been proposed including the subduction process of a lithospheric plate in this study a relocation of the seismicity of the area using a jhd algorithm for the period 1950 1995 has been performed which shows a specific hypocentre pattern that is not compatible with plate subduction in addition the direction of the stresses acting in the area has been determined through a comprehensive study of all existing focal mechanisms together with calculations for 19 new earthquakes with sufficient data to determine the focal solution after considering all these data the absence of intermediate shocks in the central part of the alboran basin and the predominantly thrusting mechanisms at the borders of the basin with pressure axes perpendicular to the front we consider a delamination process as a possible mechanism acting in the area

re evaluation of seismic intensities and relocation of 1969 saint vincent cape seismic sequence a comparison with the 1755 lisbon earthquake seismic intensity for the february 28 1969 mw 7 8 earthquake have been re evaluated using original documents in local archives such as contemporary newspapers council minutes monographic studies among other sources for spain portugal and morocco and answers to macroseismic questionnaires for morocco this information is used to plot a new intensity map for the whole region affected by the earthquake portugal spain and morocco the intensity values vary from viii to ix in the e w coast of algarve southern portugal to ii iii furthermore we have relocated the hypocentres for main shock and 24 aftershocks using a new 3d crustal velocity model for the gulf of cadiz region and a non linear probabilistic location methodology most of them previously lacking a depth estimate the new locations show an e w distribution of epicenters with focus located in the uppermost mantle most of them with depths between 30 and 50 km no earthquakes have been located at depths shallower than 30 km a comparison between peak ground accelerations pgas estimated from the observed intensities for the 1969 and the lisbon 1755 earthquakes and synthetic pga values generated assuming two different scenarios using the 1969 and 2009 earthquakes for the 1755 lisbon event shows that the observed damage produced by the 1755 earthquake may be better explained assuming a reverse dip slip mechanism oriented in ne sw direction similar to that of the 2009 earthquake rather than assuming focal mechanism similar to that of the 1969 earthquake

the relative locations of multiplets in the vicinity of the western almeria southern spain earthquake series of 1993 1994 summary we have analysed 721 earthquakes 1 5jmbj5 0 of the 1993 1994 western almero a southern spain series and the following seismicity in the area until 1998 among the data there are several multiplets events characterized by very similar seismograms at the short period stations of the local network we detected similar seismograms using crosscorrelation analysis of the p and s arrivals and classified similar events into families or clusters we found 39 multiplet clusters of 3 33 events within each cluster relocations relative to a master event have been calculated by using the interpolated cross correlation maxima for the precise relative timing of p and s phases at each station relative arrival times have been compared for all the possible selections of the master event and adjusted by forming the mean value after removing the outliers the distribution of the stations does not permit a satisfactory resolution of focal depths but relative epicentres have been determined with an accuracy of a few tens of metres typically they draw well defined lineaments and show two dominant strike directions n120u 130ue and n60u 70ue these directions are coincident with known fault systems in the area and with the source parameters of three of the largest events mw 4 8 3 6 and 4 9 which were estimated from waveform modelling of near field acceleration records at a single station consistent with previous studies distances within multiplets typically several tens of metres are for the most part clearly smaller than the fracture radii of these events this indicates repeated slip on the same fault segment it was possible to obtain precise relative locations between several nearby clusters thereby imaging a very heterogeneous seismotectonic fine structure of the source area i e the positions of adjacent active fault segments and the fragmentation of the crust into small approximately 1 km tectonic blocks