testing the sensitivity of geomorphic indices in areas of low rate active folding eastern betic cordillera spain abstract active deformation structures have an incidence in topography that can be quantified by using geomorphic indices most of these indices have been checked in faulted regions with high deformation rates the application of several geomorphic indices hypsometric curve analysis normalized stream length gradient and valley width to valley height ratio to the drainage network of the southern limb of the sierra de las estancias antiform internal zones eastern betic cordillera where low rate active folding has been recognized allows us to investigate the suitability of these indices to identify active structures in such a scenario hypsometric curves clearly identify regions with recent uplift and young topography but they do not provide any constraint on the location of active folds local valley width to valley height index variations have been detected just coinciding whit the position of ene wsw active folds normalized stream length gradient index serves to locate active folds in areas of hard rock substratum but not in those areas with soft sediments neogene quaternary sedimentary basins this is most likely due to the fact that in the basins erosion is much more intense than in the hard rock sectors in view of these results we consider that geomorphic indices constitute a valuable tool for identifying sectors affected by low rate uplift related to active folding with the best results obtained in hard rock areas

seismic risk in turkey the aegean and the eastern mediterranean the occurrence of large magnitude earthquakes summary the file of turkish seismicity developed by kandilli observatory istanbul for earthquakes to 1970 is extended here up to 1978 using 1sc and pde data entries into this file are maintained on the surface wave magnitude scale m and conversion of body wave magnitude mb to m has been carried out where necessary using a formula derived for turkish earthquakes completeness analysis suggests that magnitudes m 4 5 may be used for statistical evaluation of seismic risk this file is analysed by a range of methods to provide a suite of risk forecasts forecasting results from least squares and maximum likelihood estimates of the whole process gutenberg richter cumulative frequency law of earthquake magnitude occurrence and from the part process of gumbel s first extreme value distribution all show small systematic differences in forecasts but all three methods lead to magnitude forecasts which fall well within the range of standard deviation however these forecasts are obtained by subdividing turkish seismicity in a cellular manner and many of these cells show curvature of the earthquake frequency magnitude distribution curve concave with respect to the origin gumbel s third asymptotic distribution of extreme values is chosen as an appropriate statistical description approximate upper bounds o to earthquake surface wave magnitude occurrence are evaluated and estimates of largest magnitudes expected over an interval of 75yr are forecast with uncertainties values of w are asymptotic uncertain and theoretically correspond to infinite return periods strain energy release diagrams are then invoked to estimate empirically the large magnitude m which is equivalent to the total strain energy which may be accumulated in a region this equivalent magnitude m is consistently less than w and there is a finite waiting time typically ranging from about 15 to 70 yr during which the energy equivalent to m3 may be accumulated

a strike slip fault corridor within the alpujarra mountains betic cordilleras spain in a long corridor in the internal zone of the betic cordilleras bounded to the north by the sierra nevada and to the south by the sierras lujar contraviesa and gador two discernible bands of strike slip faults exist these bands lie in an approximately e w direction and are well exposed throughout and beyond the 85 km long belt the characteristic features of strike slip faults such as cataclastic rocks composed of variously textured fault breccia which also include fragments of rocks up to several metres in size incipient foliation and striation demonstrate the right lateral nature of the displacement there are also fractures which run in a nw se and nne ssw direction and apparently originated after formation of the e w faults the magnitude of lateral displacements is difficult to calculate evidence of considerable vertical movement can be found locally these strike slip displacements have essentially occurred since the middle miocene period and might still be taking place

historical earthquake activity of the northern part of the dead sea fault zone southern turkey abstract the northern part of the dead sea fault zone is one of the major active neotectonic structures of turkey the main trace of the fault zone called hacipasa fault is mapped in detail in turkey on the basis of morphological and geological evidence such as offset creeks fault surfaces shutter ridges and linear escarpments three trenches were opened on the investigated part of the fault zone trench studies provided evidence for 3 historical earthquakes and comparing trench data with historical earthquake records showed that these earthquakes occurred in 859 ad 1408 and 1872 field evidence palaeoseismological studies and historical earthquake records indicate that the hacipasa fault takes the significant amount of slip in the northern part of the dead sea fault zone in turkey on the basis of palaeoseismological evidence it is suggested that the recurrence interval for surface faulting event is 506 42 years on the hacipasa fault

active faulting and folding along the jumilla fault zone northeastern betics spain abstract the jumilla fault zone jfz is an ene wsw topographic lineament in the external part of the eastern betic cordillera it represents an active fault three small basins are aligned along the jfz the la celia alqueria and jumilla basins the tectonic geomorphology of the la celia and alqueria basins consists of folds a set of normal fault scarps strike slip lineaments fault springs tectonically modified drainage lines and elevated gypsum anhydrite diapirs two of the scarps are normal faults generated by the extensional collapse of one of the folds the other scarps are secondary normal faults generated by transtensional left lateral motions along the jfz normal fault scarps that developed on conglomerates are considerably steeper 30 than those affecting softer marly materials the onset of fault activity is constrained by the late tortonian messinian age of the sedimentary rocks in the basins interbedded lavaflows and lamproitic dykes in the lacustrine sediments have been dated at 7 6 7 2 ma however the morphology of fault scarps and relief of the diapirs suggest a younger age of the deformation results from modelling of fault scarp evolution indicate middle pleistocene and younger ages of faulting and scarp formation furthermore in at least one of the fault scarps quaternary alluvial pediment deposits are involved in the deformation the drainage pattern anomalies and moderate earthquake activity mb 4 2 in the jfz also indicate slow ongoing tectonic activity in addition the ene prolongation of the jfz outside the study area shows geodetic displacement rates of approximately 2 mm year we thus conclude that the jfz is still active despite the general lack of post messinian deposits in the studied basins the discrepancy between the age of the tectonic landforms and the late neogene age of the basin infill can be explained by an endo to exhorheic change in the drainage system due to the capture of the ancient basin lake system by tributaries of the nearby segura river the cessation of sedimentation in the basins resulted in the preservation of tectonic landforms

active tectonics and human survival strategies tectonic movements continuously remould the surface of earth in response to plate motion yet such deformation is rarely taken into account when assessing landscape change and its impact on human land use except perhaps as an occasional hazard to human life or a temporary disruption in the longer term parems of human history however active tectonics also create and sustain landscapes that can be beneficial to human survival forming a complex topography of potentially fertile sedimentary basins enclosed by mountain bard that can facilitate the control and exploitation of food resources especially animal prey we discuss the tectonic history of northwest greece and show how the paleolithic sites of the region are located to take advantage of tectonically created features at both a local and a regional scale we suggest that the association of significant concentrations of early paleolithic sites with tectonically active regions is not coincidental and that on the longer time spans of human biological evolution active tectonics has been an importam selective agent contributing to the development of the human species as an intelligent predator

the summit erosion surfaces of the inner betic cordillera their value as tools for reconstructing the chronology of topographic growth in southern spain erosion surfaces at the top of mountain ranges have suggested to geomorphologists that the earth s crust can undergo rapid pulses of uplift during which rates of denudation fail to balance with rates of crustal uplift thereby preserving much of the initial plateau topography as it rises to greater elevations here we analyze a regionally extensive population of mappable planar surfaces which crown several major tectonically active sierras of the inner south eastern betic cordillera se spain based on a synthesis of long term landscape evolution involving landform reconnaissance dem based morphometric analysis structural geology sediment provenance analysis and field stratigraphy we conclude that the summit surfaces are a mosaic of discrete post orogenic erosion surfaces that each developed in relation to mediterranean marine base levels at a time when the sierras formed a series of low elevation islands they are not therefore fragments of a once regionally continuous paleoplain the summit surfaces were partly the result of shallow angle detachment faulting during the middle miocene in response to lithospheric slab detachment where evidence exists that the resulting low relief topography was reworked by marine abrasion during the tortonian sea level rise the terminal age of the surfaces is latest miocene age bracketing based on stratigraphic correlations among the many depocentres of the region and on published thermochronological data indicates that some erosion surfaces locally formed in less than 3 million years 8 ma 5 7 ma they were subsequently uplifted to their current elevations 1 7 to 2 km by pliocene to quaternary neotectonics in at least two major pulses

fault generated mountain fronts in southeast spain geomorphologic assessment of tectonic and seismic activity abstract tectonic activity of se spain is evaluated through the application of a general morphometric analysis over 17 different mountain fronts the selected fronts are distributed along the two most prominent crustal scale structures of the mediterranean sector of spain the eastern betic shear zone ebsz and the valencia trough geomorphic indexes used in this study are mountain front sinuosity index smf and valley floor width ratio vf this work is largely based on the smf vf regression analysis of the studied fronts together with previous available data from sw usa the development of mountain fronts in both different lithologies and tectonic contexts enabled characteristic morphometric signatures for different activity scenarios tectonic activity classes to be obtained this study thus indicates that variations of mountain front geomorphology triggered by different styles of faulting can be detected by morphometric analysis it is demonstrated that discrete uplift rates of 0 15 0 08 m ka are sufficient to keep relatively low smf values down to 1 4 in active fronts class 1 taking into account the reported uplift rates and preliminary palaeoseismic data for some of the class 1 studied fronts recurrence periods for surface rupture events can be theoretically bracketed for se spain recurrence periods for class 1 fronts could theoretically range between 10 000 and 12 500 years for maximum slip conditions and 1750 and 2600 years for minimum slip conditions inactive fronts class 3 develop under uplift rates down to 0 03 m ka and tested recurrence intervals for rupture events range between 25 000 and 50 000 years class 2 fronts of intermediate characteristics and activity display uplift rates between 0 07 and 0 03 m ka

the late cenozoic landscape development in the westernmost mediterranean southern spain abstract the terrains of the western costa del sol in the westernmost mediterranean represent an outstanding example of the influence of major tectonic and climatic factors in the development of the landscape this region belongs to the alboran domain which is a small continental lithosphere fragment embedded between the large eurasian and african plates the territory between malaga and marbella is composed mainly of the sierra de mijas and three adjacent subsidence areas malaga torremolinos and fuengirola basins from the late miocene dip faults of approximate directions n s ne sw and nw se limited the sierra de mijas with respect to the adjacent subsidence areas and have marked the main features of the coastal morphology since then the sierra underwent mainly erosive processes linked to strong uplifting while the surrounding basins were subjected to alternate stages of sedimentation and erosion thus the paleogeographic and geomorphological evolution has been driven both by the regional tectonics and by significant base level changes ranging from the spectacular messinian low stand to the catastrophic overflow at gibraltar followed by the global late tertiary and quaternary sea level changes in the mountain relief three different erosive leveling surfaces have been recognized which developed in a staggered sequence during the miocene and are currently fragmented by tectonics at different elevations the first two leveling surfaces continental in origin were carved during the middle miocene pro part the late one correlating with upper miocene marine deposits from the malaga basin appears to correspond partially to an abrasion platform developed during the highstand of the late tortonian the strong incision of the fluvial network especially due to the low sea level during the messinian salinity crisis but also to the tectonic rise of the sierra has largely eroded these surfaces which can be recognized only in narrow inter fluvial areas the noteworthy marine transgression in the miocene pliocene transition reached the edge of the sierra de mijas developing both a broad marine abrasion platform around it and the main stage of sedimentary filling in the malaga basin tectonics combined with sea level changes influenced the formation of a lower second abrasion platform in the torremolinos sector and along the s edge of the sierra showing continuity with the late zanclean marine deposits in the torremolinos and fuengirola areas during most of the late pliocene and the gelasian the region remained emerged and subjected to erosion conversely climate eustatic changes throughout the pleistocene and holocene led to the development of three major generations of progradant alluvial fans interrupted by stages of erosion and incision of the fluvial network in parallel up to five episodes of travertine build up occurred usually coinciding with the humid and warm odd numbered isotopic stages

rate of strike slip motion on the amanos fault karasu valley southern turkey constrained by k ar dating and geochemical analysis of quaternary basalts the left lateral amanos fault follows a 200 km long and up to 2 km high escarpment that bounds the eastern margin of the amanos mountain range and the western margin of the karasu valley in southern turkey just east of the northeastern corner of the mediterranean sea regional kinematic models have reached diverse conclusions as to the role of this fault in accommodating relative motion between either the african and arabian turkish and african or turkish and arabian plates local studies have tried to estimate its slip rate by k ar dating quaternary basalts that erupted within the amanos mountains flowed across it into the karasu valley and have since become offset however these studies have yielded a wide range of results ranging from 0 3 to 15 mm a 1 which do not allow the overall role and significance of this fault in accommodating crustal deformation to be determined we have used the cassignol k ar method to date nine quaternary basalt samples from the vicinity of the southern part of the amanos fault these basalts exhibit a diverse chemistry which we interpret as a consequence varying degrees of partial melting of their source combined with variable crustal contamination this dating allows us to constrain the quaternary slip rate on the amanos fault to 1 0 to 1 6 mm a 1 the dramatic discrepancies between past estimates of this slip rate are partly due to technical difficulties in k ar dating of young basalts by isotope dilution in addition previous studies at the key locality of hacilar have unwittingly dated different chemically distinct flow units of different ages that are juxtaposed this low slip rate indicates that at present the amanos fault takes up a small proportion of the relative motion between the african and arabian plates which is transferred southward to the dead sea fault zone it also provides strong evidence against the long standing view that its slip continues offshore to the southwest along a hypothetical left lateral fault zone located south of cyprus

late quaternary large scale rotational slides induced by river incision the arroyo de gor area guadix basin se spain the arroyo de gor is a highly incised stream up to 200 m that has eroded into the pliocene pleistocene infill of the guadix basin in the betic cordillera se spain this paper concentrates on a particular reach of this stream namely the cenascuras gorafe reach where abundant inactive rotational slides can be recognized on both hillslopes of the canyon shaped valley the rotational slides have surface areas of 5 15 ha and volumes of mobilized material of 5 15 hm3 these rotational slides can be recognized by their main scarps which are still well featured at both margins of the valley as well as by the counter hillslope rotation of the strata in their bodies the surfaces of rupture are concave their width being greater than their length i e the landslides are elongated in a direction perpendicular to the landsliding displacement and parallel to the stream at depth the surfaces of rupture developed on fine grained sediments mostly clays underlying the conglomerates and sands affected by the rotational slides the clays at the surface of rupture are smectite rich and show several features produced by the landsliding such as striations and sigmoidal shaped structures the cenascuras gorafe canyon has been developed by a combination of entrenchment fracturing and landsliding initial deep entrenchment of the stream is attributed to a base level lowering related to the capture of the former endorheic basin by the gualdalquivir river in the late pleistocene this river incision created a canyon with subvertical unstable walls which due to gravitational instability would give way to vertical open tension cracks some distance from the canyon edge the tension cracks would end at depths equal to the base of the canyon which also coincides with the contact between the conglomerates and the underlying clays the rotational slides are thought to have occurred during heavy rains by a combination of piping which would have lengthened the tension cracks and infiltration which would reduce the shear strength along the gently dipping contact between conglomerates and the underlying clays thus the blocks bounded by the tension cracks and the subhorizontal lithological contact would slide under their own weight on the subhorizontal surfaces of reduced shear strength several age constraints lead us to tentatively assign the landslides to the isotope stage 5 around 32 ka an interglacial period agreed to be wetter and slightly warmer than the present day semi arid climate

kinematics of the amanos fault southern turkey from ar ar dating of offset pleistocene basalt flows transpression between the african and arabian plates

tectonic significance of the present relief of the betic cordillera abstract tortonian calcarenites of the betic cordillera were deposited in coastal or very shallow marine environments and represent an ideal marker for estimating vertical movements from the late miocene to the present a map showing the heights at which these tortonian marine rocks are situated has a clear correlation with the present relief indicating that today s relief has been formed since the tortonian there is also a good correlation between present relief and the bouguer anomaly distribution in the betic cordillera as well as with crustal thickness likewise the present relief is directly related to the geodynamic setting of a horizontal n s to nnw sse compression and an almost perpendicular extension along with isostatic readjustment existing in the betic cordillera from the tortonian as a result of these regional stresses faults and folds have produced notable vertical movements the highest rates of uplift of the betic cordillera coincide with large antiforms in particular those of the sierra nevada and the sierra filabres several subsiding sectors also exist for example the granada basin or the guadalquivir basin the foreland guadalquivir basin has a complex history because the uplift in its eastern sector and subsidence in the western sector coexisted during the late tortonian today the whole betic cordillera is characterized by differential regional uplift even in the aforementioned subsiding sectors

transposition of foliations and superposition of lineations during polyphase deformation in the nevado filabride complex tectonic implications detailed structural analysis in a ca 80 km2 area of the western nevado filabride complex betic cordillera reveals a heterogeneous internal structure characterized by multiple cross cutting foliations and lineations that locally transpose earlier ones the large scale geometry of these fabrics conflicts with continuous westward to south westward tectonic transport related to thrusting or crustal extension and mismatches a previously inferred extensional detachment in the area multiple crenulation lineations can be distinguished in the field and correlated with five foliation intersection axes fia1 5 preserved in garnet and plagioclase porphyroblasts of the western sierra nevada these indicate crustal shortening in different directions associated with vertical foliation development and intermitted stages of gravitational collapse producing horizontal foliations the large spread of lineation and fold axes trends in the nevado filabride complex results from the mixed presence of multiple generations of these structures whose distinction is critical for tectonic models the five principal fia trends remarkably match successive vectors of relative africa iberia plate motion since the eocene suggesting that deformation of the nevado filabride took place during this period although peak metamorphism in at least some of its parts was reached as late as the middle miocene

time dependent modelling of a mountain front retreat due to a fold to fault controlled lateral spreading abstract the eastern betic cordillera spain exemplifies at the sierra de aitana an impressive case of lateral spreading which involves a mountain anticline ridge dislodged by a post orogenic extensional tectonic the deep trenches testify the ongoing gravitational slope deformation featured by a rock mass lateral spreading the sierra de aitana anticline ridge was dislodged along a normal fault zone which generated a scarp with a kilometric lateral continuity the lateral spreading originated because eocene limestone overlays eocene marls inducing a continuous evolution over time due to visco plastic deformations and isolating huge prismatic blocks to quantify the creep driven stress strain effects at sierra de aitana ridge the mechanical and rheological parameter values of the involved rocks were quantified through field and laboratory tests which allowed to constrain an engineering geological model based on equivalent continuum approach a stress strain numerical modelling aimed at back analysing the sequential morpho structural evolution of the sierra de aitana anticline ridge was performed by reproducing the retreat of the ridge front and the time succession of faults re activations a time dependent solution was approached by assuming a time dependent creep configuration of the modelling and a parametric solution adopted to calibrate rock mass rheology also taking into account tectonic displacement due to the aitana normal fault system by simulating these element as interface in the discretized domain influence of pre existing joint sets by assuming a main anisotropy in the elasto plastic failure solution admissible variations of the regional stress field related to compressive and extensional phases and a generalised visco plastic behaviour representing the ductile marls the numerical modelling outputs that the lateral spreading mainly evolved as a creep driven process while stress release induced by tectonic activity is not sufficient to justify the observed landforms the obtained results highlight a not negligible role of inherited structural elements for regulating the time evolution of the ongoing gravitational process at the sierra the aitana anticline

earthquake clustering in the eastern mediterranean during historical times most coastal sectors which show evidence of holocene coseismic uplift in greece and the eastern mediterranean were raised during a short period called here the early byzantine tectonic paroxysm ebtp between the middle of the fourth and the middle of the sixth century a d the areas uplifted at that time include cephalonia and zante in the ionian islands lechaion and the perachora peninsula in the gulf of corinth the pelion coast of thessaly antikythira and the whole of western crete a coastal sector near alanya in southern turkey and the entire levant coast from hatay turkey to syria and the lebanon the amount of the ebtp uplift was generally between 0 5 m and 1 0 m but reached a maximum of about 9 m in southwestern crete in several areas zante pelion coast antikythira western crete alanya the ebtp uplifted shoreline is the only evidence of holocene emergence in other areas however a similar uplift occurred earlier in the holocene levant coast or more recently cephalonia evidence of preseismic subsidence prior to the ebtp uplift has been reported from thessaly antikythira and crete in both the latter islands the ebtp uplift was preceded by a series of about 10 coseismic small subsidence movements each measuring some tens of centimeters which took place in the preceding 3000 years no evidence was observed of postseismic vertical displacements

structure and present day compression in the offshore area between alicante and ibiza island eastern iberian margin abstract this study deals with the structure and recent deformation of the eastern iberian margin extending from basement to seafloor and including the south western margin of the valencia basin the alicante shelf the ibiza channel and its southern margin descending into the algerian basin this area underwent a complex tectonic evolution linked to the back arc opening of the north western mediterranean and the concomitant contraction of the betic belt due to the collision with blocks located between africa and europe this oligo miocene structural heritage gave rise to a complex and continuous deformation through times including late miocene post orogenic extension and pliocene to quaternary compression in the western balearic area and coeval extension in the valencia basin this study presents maps of the depth to basement and base of the pliocene as well as bathymetry data and seismic lines which provide a precise integrated 3d study of the offshore domain it reveals a major reactivation of the area represented by the n80 to n60 trending structures small discontinuous folds and thrusts in the ibiza channel and a large flexure on the alicante shelf the structures are picked out by erosion surfaces or deposits linked to the messinian salinity crisis msc these markers are ubiquitous in the seismic sedimentary sequences and record the lateral and vertical deformation active from the messinian salinity crisis to the present the contraction in the western iberian margin and concomitant extension in the southern valencia basin are consistent with the regional stress field as determined from the focal mechanisms of offshore earthquakes or recent gps measurements the tectonic compression of the studied area casts doubt on the eventual propagation of the present day compressive stress from the algerian margin to the western balearic promontory

distribution of interseismic coupling along the north and east anatolian faults inferred from insar and gps data the north anatolian fault naf has produced numerous major earthquakes after decades of quiescence the mw 6 8 elazig earthquake january 24 2020 has recently reminded us that the east anatolia

fold and fault interactions during the development of an elongated narrow basin the almanzora neogene quaternary corridor se betic cordillera spain 1 elongated corridors grow in different tectonic settings mainly in areas deformed by fold and fault sets parallel to the borders the almanzora corridor however is a good example of an e w elongated asymmetrical narrow basin developed in a changing stress scenario generated by the interaction of fold and fault sets oriented parallel and oblique to the corridor borders the initial crustal thickening process was mainly related to the development of the e w oriented sierra de los filabres large antiform which constitutes a major heterogeneity during the tortonian a nw se convergent tectonic setting oblique to this already emerged antiform gives rise to a large dextral simple shear band that determines the development of a major fold las estancias antiform the asymmetrical location of minor tectonic structures faults and minor folds and the distribution of sedimentation denudation areas that finally configure the almanzora corridor synform furthermore development of nw se oriented normal faults points to ne sw orthogonal extension in a new stress field oblique to the corridor borders this region illustrates that the elongated character of the corridors may persist inherited from the orientation of previous crustal rheological heterogeneities in addition marine transgression may be produced in compressional settings favored by the synform development during initial stages of crustal thickening finally led to the relief uplift

mountain front development by folding and crustal thickening in the internal zone of the betic cordillera alboran sea boundary the boundary between the alboran sea and betic cordillera is a good example of a fold related mountain front in the internal zone of an alpine mountain range since the late miocene nnw sse convergence between the eurasian and african plates has produced shortening and related orthogonal extension to improve the characterisation of the geometry of the deep structure in the region and to establish the recent tectonic evolution of the mountain front well logs and newly acquired geophysical data multichannel reflection seismic and gravimetric surveys have been interpreted and integrated with available surface data the most marked tectonic structure corresponds to large antiforms and synforms of ene wsw trend which are related to mountain ranges and basins respectively the fold belt continues toward the northern continental shelf of the alboran sea the fold vergence is generally northwards and its amplitude decreases progressively towards sse until disappearring in a sharp boundary where the reflectors are undeformed the deep geometry suggests that fold growth started during upper tortonian times and continued its activity up to pliocene or even quaternary times the nnw sse compression produces crustal thickening and a regional and progressive southwards emersion the location of main present day deformation fronts in the internal zones contrasts with classical models where the deformation progresses towards the frontal part of external zones of cordilleras in addition this fold related deformation mountain front has features different from fault related fronts as it does not show a sharp boundary and folds that determine rectilinear mountain boundaries decrease progressively in amplitude or in wavelength up to undeformed areas

active shallow extension in central and eastern betic cordillera from cgps data abstract the betic cordillera is an alpine belt formed in the western mediterranean by the westward displacement of the alboran domain in between the eurasian and african convergent plates new cgps data from the central and eastern betic cordillera and its foreland obtained mainly from the topo iberia project allowed us to precisely determine the rate of tectonic deformation most of the displacements of the central and eastern betics are westward with a variable southwestward component in relation to the eurasian stable plate while in the iberian foreland the displacements are extremely low some deformation related to low compressional deformation occurs in the easternmost foreland basin and eastern betic cordillera the displacement increases substantially southwards and westwards in relation to present day extensional deformation major active discontinuities correspond to the nw se normal fault zones which dip westwards they are located in almeria tabernas balanegra and western sierra de gador whereas the padul fault zone located west of sierra nevada extends northwards to the granada basin nw se extensional faults are also observed to the north in the baza basin moreover the activity of dextral faults along the sorbas tabernas alpujarras guajares band generally considered as a transfer fault zone is evidenced by the displacement data these results come to demonstrate the low activity or inactivity of the large northern e w oriented folds of the central and eastern internal zone such as the sierra de los filabres antiform they also point to the possible residual activity of the northern part of the ne sw sierra nevada antiform where the maximum relief of the cordillera is found altogether our data support a heterogeneous present day westward extension that affects the upper crust of the betic cordillera and increases towards the thinned continental crust of the alboran sea and towards the west which is compatible with roll back subduction along the gibraltar arc

an evaporite bearing accretionary complex in the northern front of the betic rif orogen the guadalquivir accretionary complex forms a largely oblique prism at the northern edge of the betic rif orogen where miocene sediments plus allochthonous evaporite bearing units were accreted during the displacement of the alboran domain towards the west traditional interpretations end the tectonic structuring of the betic cordillera at the present topographic front beyond which gravitational and or diapiric processes would predominate however this study shows pervasive tectonic deformation in the outer prism with coherent oblique shortening kinematics which is achieved through an alternation of roughly n s arcuate thrust systems connected by e w transfer fault zones these structures accord well with the geophysical models that propose westward rollback subduction the main stage of tectonic activity occurred in the early middle miocene but deformation lasted until the quaternary with the same kinematics evaporite rocks played a leading role in the deformation as evidenced by the suite of ductile structures in gypsum distributed throughout the area s and l gypsum tectonites scaly clay fabrics and brittle fabrics coexist and consistently indicate westward motion top to 290 with subordinate n s contraction almost perpendicular to the transfer zones this work reveals ductile tectonic fabrics in gypsum as a valuable tool to elucidate the structure and deformational history of complex tectonic melanges involving evaporites above the decollement level of accretionary wedges

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

eustatic and tectonic controls on quaternary ras leona marine terraces strait of gibraltar northern morocco well preserved quaternary staircased marine terraces appear on ras leona limestone relief this is a peculiar sector of the betic rif cordillera lying in the four way junction between the atlantic and the mediterranean and europe and africa the age and altitude correlation of the ras leona terraces with travertine covered lateral equivalent terraces fashioned in the neighbouring beni younech area and comparison with those along the moroccan atlantic coasts would suggest that the ras leona terraces were mainly formed by eustatic factors the importance of the eustasy is supported by further comparisons with spanish and moroccan mediterranean terraces and with different marine terraces developed on passive margin coasts around the world a tectonic event occurred mainly during the period between the formation of the maarifian and the ouljian terraces i e between 370 and 150 ka the moderate quaternary tectonic uplift deduced from the marine terraces and its comparison with uplifted marine terraces developed in active subduction setting disagrees with the model of an active eastwards subduction below the gibraltar tectonic arc

lithospheric structure beneath the alboran basin results from 3d gravity modeling and tectonic relevance a three dimensional gravity modeling combined with integrated heat flow and elevation modeling is conducted to map out the crustal and lithospheric mantle thickness in the alboran basin in the westernmost mediterranean a sediment corrected bouguer anomaly has been derived using a depth to the basement map and densities determined from well logs and seismic data the gravity effect of the base of the lithosphere has been removed from the sediment corrected bouguer anomaly to obtain a crustal bouguer anomaly which has been inverted for crustal thickness the resulting lithospheric structure is further constrained by elevation data under the assumption of local isostasy the low residual elevation anomalies obtained 100 m in average suggest that the area is in local isostasy particularly the medium and long wavelength topography features variations in crustal thickness range from 36 km underneath the betic and rif chains to 12 km beneath the easternmost part of the alboran sea basin in the transition to the south balearic basin in western alboran the moho lies at a rather constant depth of 18 km deepening sharply toward the gibraltar strait down to 30 32 km the base of the lithosphere shallows from 140 km depth in the gibraltar strait to 45 km depth in the easternmost alboran sea lithospheric thinning penetrates to the southeastern side of the iberian margin crosscutting topographic highs of the central and eastern betic chain our results favor mantle delamination produced by detachment and subsequent peeling away of the lithospheric mantle rather than convective removal of the lithospheric mantle either by orogenic collapse or detachment and sinking of a lithospheric slab

active tectonics in the sierra nevada betic cordillera se spain insights from geomorphic indexes and drainage pattern analysis article i nfo the sierra nevada of the central betic cordillera is a 3000 m high mountain range surrounded by neogene quaternary sedimentary basins having been uplifted since late miocene times the southern and western mountain fronts of the sierra nevada are fault bounded while the northern one is an unconformity between the neogene quaternary sediments of the guadix baza basin and the metamorphic rocks of the nevado filabride complex we have carried out a geomorphic study by examining drainage patterns and characteristics of mountain fronts in order to reveal areal variations and styles of rock uplift mountain front sinuosity smf area altitude relations hypsometric curves and valley floor entrenchment differ significantly between the northern western and southern mountain fronts the lack of important faults along the northern sierra nevada mountain front together with the elevated topographic position of the guadix baza basin average altitude is around 1100 m points to similar uplift of both geomorphic units sierra and basin in a single large scale crustal block the asymmetry factors show systematic asymmetries at both sides of the lanjaron river probably due to the presence of an active nne ssw oriented antiform in the western sierra nevada finally river profiles indicate maximal river entrenchment in the western part of the sierra nevada probably related to the uplift of the footwall of the padul niguelas fault system therefore our geomorphic analysis suggests that the western part of the sierra nevada is tectonically active by means of a combination of normal faults along the mountain front and nne ssw oriented active folds which in turn likely have a gravitational origin related to the exhumation of the footwall of the normal fault system

present day seismicity and seismotectonics of the cilician basin eastern mediterranean region of turkey the nature of the interaction between the anatolian arabian and af rican plates is an important problem of northeastern mediterranean tectonics the dead sea fault and east anatolian fault zone are the most prominent structural elements in this region the cilician basin which is located at the junction of these faults is known to have a very active seismic history however instrumental obser vations have been insufficient because of the lack of an adequate local seismic net work to monitor ongoing seismic activity and to analyze the seismotectonics of the cilician region 36 to 38 n 34 to 38 e a digital seismic network of 18 stations with velocity transducers has been operated by the earth and marine sciences re search institute emsri of the scientific and technical research council of turkey tubitak since 1993 no previous studies have been carried out in this region for crustal structure an optimum 1d velocity model was obtained by using the velest algorithm for reliable determination of earthquake hypocenter locations approxi mately 2500 earthquakes detected between 1993 and 2002 with local magnitude greater than 1 5 have been located by using this optimum velocity model the most notable feature of the epicentral distribution is the presence of dense clusters of activity along local fault trends the majority of hypocentral depths of the events range between 5 and 35 km single fault plane solutions of reliable events were calculated in order to analyze the seismotectonic characteristics of the region results show that the cilicia region constitutes a wide left lateral shearing zone that indicates a diffuse plate boundary between the african arabian and anatolian plates

evidence for hydrothermal alteration and source regions for the kiruna iron oxide apatite ore northern sweden from zircon hf and o isotopes zircon grains from the kiruna iron oxide apatite ioa ore bodies in northern sweden are distinct in their hafnium and oxygen isotopic ratios compared to zircon grains from adjacent metavolcanic host rocks and related intrusions here we combine these two isotopic systems on previously dated zircon grains to improve our understanding of these ore deposits with a long debated origin contrasting theories for the formation of the kiruna iron ores suggest either 1 emplacement through immiscible silicate iron oxide melts or 2 transportation and deposition of iron by hydrothermal fluids zircon from the metavolcanic host rocks and intrusions have oxygen isotopic ratios 18 o 3 that lie below typical magmatic compositions which is evidence that roof rocks altered by meteoric water were digested into the magma in contrast the ores show an influence of a fluid that is higher in 18 o 7 based on these findings we propose the involvement of episodic magmatic hydrothermal fluids in the ore genesis of the kiruna iron ore deposits 1 the first episode related to a deep seated magmatism and to regional scale metasomatic alteration and 2 a later fluid event related to shallow intrusions and responsible for the ore formation distinct differences in the hf isotopic ratios for host rocks and intrusions e hfi 6 to 10 archean crust and ore e hfi 5 to 3 depleted mantle further allow us to screen possible fluid sources for their involvement in the ore process

3d geometry of growth strata in a fault propagation fold insights into space time evolution of the crevillente fault abanilla alicante sector betic cordillera spain this work presents a 3d geometric model of growth strata cropping out in a fault propagation fold associated with the crevillente fault abanilla alicante sector from the bajo segura basin eastern betic cordillera southern spain the analysis of this 3d model enables us to unravel the along strike and along section variations of the growth strata providing constraints to assess the fold development and hence the fault kinematic evolution in space and time we postulate that the observed along strike dip variations are related to lateral variation in fault displacement along section variations of the progressive unconformity opening angles indicate greater fault slip in the upper tortonian messinian time span from the messinian on quantitative analysis of the unconformity indicate a constant or lower tectonic activity of the crevillente fault abanilla alicante sector the minor abundance of striated pebbles in the pliocene quaternary units could be interpreted as a decrease in the stress magnitude and consequently in the tectonic activity of the fault at a regional scale comparison of the growth successions cropping out in the northern and southern limits of the bajo segura basin points to a southward migration of deformation in the basin this means that the bajo segura fault became active after the crevillente fault abanilla alicante sector for which activity on the latter was probably decreasing according to our data consequently we propose that the seismic hazard at the northern limit of the bajo segura basin should be lower than at the southern limit

the 2011 mw 7 1 van eastern turkey earthquake 1 we use interferometric synthetic aperture radar insar body wave seismology satellite imagery and field observations to constrain the fault parameters of the mw 7 1 2011 van eastern turkey reverse slip earthquake in the turkish iranian plateau distributed slip models from elastic dislocation modeling of the insar surface displacements from envisat and cosmo skymed interferograms indicate up to 9 m of reverse and oblique slip on a pair of en echelon nw 40 54 dipping fault planes which have surface extensions projecting to just 10 km north of the city of van the slip remained buried and is relatively deep with a centroid depth of 14 km and the rupture reaching only within 8 9 km of the surface consistent with the lack of significant ground rupture the up dip extension of this modeled wsw striking fault plane coincides with field observations of weak ground deformation seen on the western of the two fault segments and has a dip consistent with that seen at the surface in fault gouge exposed in quaternary sediments no significant coseismic slip is found in the upper 8 km of the crust above the main slip patches except for a small region on the eastern segment potentially resulting from the mw 5 9 aftershock on the same day we perform extensive resolution tests on the data to confirm the robustness of the observed slip deficit in the shallow crust we resolve a steep gradient in displacement at the point where the planes of the two fault segments ends are inferred to abut at depth possibly exerting some structural control on rupture extent

the role of extension in the miocene denudation of the nevado filabride complex betic cordillera se spain the internal zone of the betic cordillera se spain consists of a nappe stack of three complexes the deepest of which is the nevado filabride complex the zone is separated from the overlying alpujarride complex by a crustal scale shear zone that has variously been interpreted as a thrust or an extensional detachment a suite of 74 new apatite and zircon fission track results have been obtained from the nevado filabride complex and these have been used to define regional cooling patterns for the complex rapid cooling 105 c 200 c ma 1 is spatially related to the tectonic contact with the overlying alpujarride complex cooling to near surface temperatures occurred first in the east sierra de los filabres during the mid serravallian 12 1 ma and was completed by the early tortonian 9 8 ma in the west sierra nevada there is no correlation between fission track age and sample elevation these results are consistent with tectonic unroofing of this complex a finding that favors extension as the mechanism by which the two complexes were brought into contact extension spans the middle and earliest upper miocene 12 8 ma in the study area and therefore lasted much longer than previously documented a hypothesis is advanced which links oblique convergence between the iberian plate and the betic internal zones resulting in crustal contraction at depth with orogen parallel extension in the middle and upper crust

salt deposition and brine evolution in the granada basin late tortonian se spain abstract a group of sedimentary basins in the betic chain were formed during the middle late miocene as a result of the closure of the tethys during the alpine orogeny in the late miocene tortonian messinian the connections between the atlantic ocean and mediterranean sea were interrupted and those basins hosted major evaporites the granada basin an inner basin located far from the mediterranean contains a thick rock salt deposited during the latest tortonian in the transition from marine to non marine conditions in the centre of the basin three halite bearing units overlie a basal anhydrite bed the lower halite unit the intermediate sandstone unit and the upper halite unit fluid inclusion compositions and bromine concentrations in halite together with stable isotopes 34 s sulfate 18 o sulfate and 87 sr 86 sr indicate a mixture of different inflow waters in the granada basin beginning with a marine lagoon that evolved into a salt pan strongly isolated from the sea saline waters evolved from sulfate rich marine derived to sulfate depleted non marine brines influenced by the addition of cacl 2 rich inputs these cacl 2 rich waters were probably linked to thermal fluids associated with a major crustal fracture system crevillente or cadiz alicante fault system that cuts through the granada basin

onshore and offshore compressional tectonics in the eastern betic cordillera se spain abstract this study concerns the northern terminal splay of the eastern betic shear zone betic cordillera se spain where the bajo segura basin lies and its offshore prolongation along the western mediterranean margin we have integrated seismic reflection profiles with gravimetry seismicity wells and outcrop data from the bajo segura basin and the alicante shelf in order to determine the current geodynamic setting of the area the results indicate that the same compressional structures in upper miocene quaternary rocks are observed both on and offshore in the onshore bajo segura basin there are ene wsw growth folds related to reverse faults in the basement in the alicante shelf the main structure is an ene wsw anticlinorium which deforms upper miocene quaternary syntectonic deposits these compressional structures are still active at present as shown by the offshore seismicity from the structural analysis and focal mechanisms of the earthquakes we conclude that the bajo segura basin and its adjacent shelf have been subject to nnw sse compression since late miocene until the present folding and reverse faulting of the upper miocene quaternary sedimentary cover and of its basement have accommodated this compression the main active structures onshore located in the bajo segura basin extend eastwards into the mediterranean sea this fact is interpreted as the eastern betic shear zone continues offshore to the east

the palomares brittle ductile shear zone of southern spain the palomares shear zone is a major neogene quaternary strike slip zone which transects the crust of the betic cordillera in se spain the shear zone and the mechanisms that led to its formation are discussed and illustrated on the basis of detailed compilations of both the local and regional geology it is emphasized that the formation of the palomares shear zone was not an isolated tectonic event but part of a complex neogene tectonic history the neogene evolution of the betic rif orogen and its central alboran basin is characterised by the following events 1 emplacement of the alboran diapir with resulting nappe shedding from the overlying crust between 25 and 20 ma ago 2 onset of the subsidence of the alboran basin between 20 and 15 ma ago due to cooling of the alboran diapir and the overlying crust 3 formation of the cabo de gata volcanic chain between 15 and 8 ma ago and 4 refolding of the nappe sheets in the betic rif orogen into a basin and range structure about 7 ma ago continuous activity of the crevillente fault of southern spain may have occured over a period from 20 ma ago up to the present the interrelated palomare fault in se spain was probably formed between 15 and 8 ma ago and seem to be active still the palomares shear zone affects a rock volume 44 km wide at least 80 km long and 30 km deep a shear strain distance diagram constructed across the palomares shear zone and its axial palomares fault involves a new method to estimate or constrain the shear strain magnitude along brittle ductile shears the typical tensor shear strain rates in the approximately 20 km thick ductilely deformed walls of the palomares fault are of the order 10 13 10 14 s 1 the tensor shear strain rate along the palomares fault itself is of the order 10 12s 1 and the time averaged relative displacement rate of its walls is about 2 mm a 1 the range of strain rates within the palomares shear zone are interpreted to be due to a combination of various flow softening mechanisms geometric structural thermal and strain rate softening these softening mechanisms might explain the difference in vertically averaged viscosities of 1020 pa s and 1025 pa s or lower suggested for the crustal rocks in the palomares fault proper and that of the relatively rigid boundaries of the palomares shear zone respectively

irregular earthquake cycle along the southern tianshan front aksu area china 1 a long deformation record 16 5 ka showing nonsteady earthquake recurrence is established for the aksu thrust tianshan china on the basis of cosmogenic 10be dating of faulted surfaces topographic leveling across the aksu fault scarp indicates up to 10 m uplift across a moraine abandoned 16 5 ka and similar uplift of 6 m across two inset surfaces yielding ages of 12 5 and 5 ka successively smaller uplifts of terraces younger than 5 ka indicate that three or more major earthquakes occurred during this period these data show that the aksu thrust fault was quiet for at least 7500 years and active in the last 5000 years and probably in the interval 16 5 12 5 ka the seismic cycle along the aksu thrust fault over the last 16 500 years was thus strongly irregular showing long quiescence and clustering which is a challenge for paleoseismology and hazard assessment this irregularity also makes it more difficult to estimate long term shortening rates nevertheless we are able to constrain a minimum total shortening rate 7 mm yr across the southern tianshan front for the last 12 500 years that is about a third of the total geodetic rate for the western tianshan 20 mm yr

the 1759 earthquake in the bekaa valley implications for earthquake hazard assessment in the eastern mediterranean region analysis of macroseismic data based on primary sources for large though infrequent historical earthquakes ms 6 5 that occurred along an approximately 350 km long segment of the northern part of the dead sea fault system primarily in lebanon and syria for the period 1100 1988 reveals the following 1 ten events occurred in three relatively short periods tens of years with repeat times of 200 350 years 2 the events most probably broke this north segment of the dead sea fault system possibly including the westernmost segment of the east anatolian fault system near the border between syria and turkey 3 the lack of such large events during the past 100 years should not be interpreted to minimize potential earthquake hazard in this region and 4 the ms 7 plus earthquake on november 25 1759 almost certainly produced surface faulting probably along the yammouneh fault in the bekaa valley and caused heavy destruction with great loss of life in numerous villages and towns including safad damascus beirut and baalbek this main event was preceded by a ms 6 plus foreshock on october 30 1759 in the southern part of the epicentral area of the main shock near the towns of safad and qunaitra which were almost totally destroyed with considerable loss of life

stress distribution at the transition from subduction to continental collision northwestern and central betic cordillera 1 we analyze focal mechanisms of shallow intermediate earthquakes in a nw se transect along the western betic cordillera and alboran sea and deep earthquakes located in the central betics to constrain the state of stress at the gibraltar arc slow convergence area shallow earthquakes 620 km show very similar focal mechanisms fitting the general slab behavior of resistance to further descent at the 660 km discontinuity seismicity features evidence the present day stress distribution in a context of transition from subduction to continental collision

landscape response to strike slip faulting linked to collisional settings quaternary tectonics and basin formation in the eastern betics southeastern spain abstract neotectonic behaviour of the eastern betics southeastern spain has been controlled by the presence of a large left lateral shear zone this is an intraplate transcurrent zone probably decoupled by a mid crustal detachment horizon the morphological expression of this crustal structure is a sigmoidal corridor in which the main quaternary basins are located three types of morphostructural domains can be distinguished in the sigmoidal corridor the central segment and the northern and southern terminal splays the central segment is characterized by wrench tectonics whilst the southern and northern terminal splays are controlled by transtensional and transpressional tectonics respectively the quaternary morphostructural pattern is only the more recent picture of the tectonic processes that have controlled the late orogenic evolution of the eastern betics the indentation of the aguilas arc accompanied by thin skinned thrusting and tectonic escape in its easternmost sector and extensional collapse accompanied by thin skinned stretching in its westernmost sector

pleistocene raised marine terraces of the spanish mediterranean and atlantic coasts records of coastal uplift sea level highstands and climate changes detailed geological mapping morphostratigraphic palaeontological and geochronological uranium series analyses were undertaken on the raised marine terraces and interbedded terrestrial deposits along the spanish peninsular and insular atlantic and mediterranean coasts several sets of pleistocene shallow marine to coastal deposits exposed in a staircase arrangement are interpreted as being emplaced during sea level highstands coeval with interglacials or interstadials correlating with marine oxygen isotopic stages ois 5a 5c 5e 7 9 11 and older up to three highstands have been identified in deposits formed during ois 5e close to the end of ois 5e there is a record of sudden changes in sea surface conditions and climate marked by the disappearance of a major proportion of the warm senegalese fauna switches from oolitic to non oolitic facies and accumulation of boulder beaches dating of the coral cladocora caespitosa found in a layer that also contains strombus bubonius confirms the occurrence of warm fauna in the mediterranean basin during ois 7 as previously suggested by hillaire marcel et al 1986 goy et al 1986a b zazo and goy 1989 also the occurrence of warm faunas in deposits corresponding to an older interglacial probably ois 9 or 11 in the balearic islands suggests similar oceanographic conditions sea surface temperature assuming constant salinity during the last interglacial and at least two interglacials of the middle pleistocene in the western mediterranean a 2002 elsevier science b v all rights reserved

late neogene recent uplift of the cabo de gata volcanic province almeria se spain abstract cabo de gata is a miocene volcanic province in the betic cordillera in southeastern spain the distribution of coastal deposits in the successive marine sedimentary units overlying the last volcanic episode about 7 5 ma old has been used to reconstruct the post volcanic palaeogeographic evolution of the region during the late neogene the current elevation of well dated shoreline marker rocks has been used to estimate uplift amount and rates since the late tortonian a n45 e aligned the strike of the carboneras fault system topographic relief was emergent in the cabo de gata region the extension and height of this island increased throughout the late neogene smaller independent islands were emergent and finally became connected to the main island during the messinian the carboneras and agua amarga pliocene sub basins were the last two marine basins prior to the final emergence of the region since the last volcanic eruption ca 7 5 ma maximum uplift of sedimentary rocks in cabo de gata has taken place on the western margin of the n45 e aligned palaeorelief the altitude of the shoreline marker rocks in the successive sedimentary units decreases eastwards to the present day coast and northwards of the rambla del plomo uplift rates since deposition remain nearly constant for the successive messinian rocks and decrease slightly for the lower pliocene outcrops most of the uplift took place before the pliocene while the main island enlarged uplift amounts and rates since deposition of the upper neogene sedimentary units in the cabo de gata area are similar to the ones estimated for laterally equivalent units in the eastern betic basins approximately 50 m ma despite its volcanic nature and the occurrence of the carboneras fault system the cabo de gata probably became elevated as a consequence of regional uplift in connection with the rest of the betic cordillera

shear wave velocity structure of the south eastern part of the iberian peninsula from rayleigh wave analysis in this study we present the lithospheric structure of the south eastern part of the iberian peninsula by means of a set of 2d images of shear velocity for depths ranging from 0 to 50 km this goal will be attained by means of the inversion of the rayleigh wave dispersion for it the traces of 25 earthquakes occurred on the neighbouring of the study area from 2001 to 2003 will be considered these earthquakes have been registered by 11 broadband stations located on iberia all seismic events have been grouped in source zones to get an average dispersion curve for each source station path the dispersion curves have been measured for periods between 2 and 45 s by combination of two digital filtering techniques multiple filter technique and time variable filtering the resulting set of source station averaged dispersion curves has been inverted according to the generalized inversion theory to get s wave velocity models for each source station path later these models have been interpolated using the method of kriging to obtain a 2d mapping of the s wave velocity structure for the south eastern part of iberia the results presented in this paper show that the techniques used here are a powerful tool to investigate the crust and upper mantle structure through the dispersion analysis and its inversion to obtain shear velocity distributions with depth by means of this analysis principal structural features of the south eastern part of iberia such as the existence of lateral and vertical heterogeneity in the whole study area or the location of the moho discontinuity at 30 km of depth with an average s velocity of uppermost mantle of 4 7 km s have been revealed other important structural features revealed by this analysis have been that the uppermost of iberian massif shows higher velocity values than the uppermost of the alpine domain indicating that the massif is old and tectonically stable the average velocity of the crust in betic cordillera is of 3 5 km s while in the iberian massif is 3 7 km s all these features are in agreement with the geology and other previous geophysical studies

flow dynamics at the origin of thin clayey sand lacustrine turbidites examples from lake hazar turkey turbidity currents and their deposits can be investigated using several methods i e direct monitoring physical and numerical modelling sediment cores and outcrops the present study focused on thin clayey sand turbidites found in lake hazar turkey occurring in eleven clusters of closely spaced thin beds depositional processes and sources for three of those eleven clusters are studied at three coring sites bathymetrical data and seismic reflection profiles are used to understand the specific geomorphology of each site x ray thin sections and ct scan imagery combined with grain size geochemical and mineralogical measurements on the cores allow characterization of the turbidites turbidites included in each cluster were produced by remobilization of surficial slope sediment a process identified in very few studies worldwide three types of turbidites are distinguished and compared with deposits obtained in flume studies published in the literature type 1 is made of an ungraded clayey silt layer issued from a cohesive flow type 2 is composed of a partially graded clayey sand layer overlain by a mud cap attributed to a transitional flow type 3 corresponds to a graded clayey sand layer overlain by a mud cap issued from a turbulence dominated flow while the published experimental studies show that turbulence is damped by cohesion for low clay content type 3 deposits of this study show evidence for a turbulence dominated mechanism despite their high clay content this divergence may in part relate to input variables such as water chemistry and clay mineralogy that are not routinely considered in experimental studies furthermore the large sedimentological variety observed in the turbidites from one coring site to another is related to the evolution of a sediment flow within a field scale basin made of a complex physiography that cannot be tackled by flume experiments

the structure of the alboran sea an interpretation from seismological and geological data abstract almost all the earthquakes included in the catalog for the iberian maghrebian area up to 2000 have been used in order to know the structure of the alboran sea area after the verification of the aleatory nature of the errors in their spatial localization a new focal mechanisms catalog has also been used as well as many of the available geological data during the mesozoic and till the oligocene the betic rif internal zone was situated further e but with the opening of the algero provencal basin in the early miocene the betic rif internal zone moved to the w contemporary the alboran sea was created as the western prolongation of the algero provencal basin the betic rif internal zone overthrused part of the iberian and african plates producing the partial sinking of both plates and being responsible of the intermediate seismicity existing in the western sector of the alboran sea the intermediate earthquakes in the atlas towards the ne and wsw are not related to lithospheric sinking but to significant deep faults limiting a subplate in nw africa in the atlantic the intermediate earthquakes between the gorringe sector and gibraltar are produced in the contact between the iberian and african plates and by the important faults crossing it the existence of four very deep earthquakes is related to the previous sinking of the lithosphere originally associated to the domain in which the betic rif internal zone was situated

patterns and average rates of late neogene recent uplift of the betic cordillera se spain abstract the facies distribution in the sedimentary units infilling a series of neogene basins has been used to reconstruct the relief generation and uplift across the internal zone of the betic cordillera in southern spain uplift amounts and average rates can be estimated using the current elevation of the outcrops of well dated deposits indicative of ancient sea level positions coral reefs and coastal conglomerates record the initial development of emergent betic relief during the langhian continental and marginal marine deposits indicate the existence of a large island centred on the present sierra nevada sierra de los filabres chain by the end of the middle miocene the precursor of the sierra nevada sierra de los filabres chain originally part of this large island remained emerged whilst the surrounding areas were re invaded by the sea during the early tortonian at the end of the tortonian the inland basins granada and guadix basins became continental while the sierras de la contraviesa sierra de gador and sierra alhamilla emerged separating the alboran basin from the alpujarra tabernas and sorbas basins which became narrow passages of the mediterranean sea in contrast the sierra cabrera emerged during the late messinian suggesting a progressive uplift from west to east of the sierras south of the sierra nevada sierra de los filabres chain during the pliocene only the low areas closest to the present day coast remained as marine basins and progressively emerged throughout this stage the highest average uplift rate recorded is 280 m ma for the sierra de gador although the average uplift rates of upper neogene coastal marine rocks since depositon have maximum values of approximately 200 m ma most of the uplift of the betic mountains took place before the early pliocene the recorded uplift of neogene rocks was highest at the margins of western sierra nevada where peaks higher than 3000 m occur the average rates of uplift were lower to the east of this major relief the main sierras and depressions in the present day landscape correspond respectively to the emergent land in which uplift was concentrated and to the marine basins that existed before the final emergence of the region the altitude of the sierras reflects the time at which they became emergent the highest mountains being the first to rise above sea level

the padul normal fault activity constrained by gps data brittle extension orthogonal to folding in the central betic cordillera abstract the padul fault is located in the central betic cordillera formed in the framework of the nw se eurasian african plate convergence in the internal zone large e w to ne sw folds of western sierra nevada accommodated the greatest nw se shortening and uplift of the cordillera however gps networks reveal a present day dominant e w to ne sw extensional setting at surface the padul fault is the most relevant and best exposed active normal fault that accommodates most of the ne sw extension of the central betics this wsw wards dipping fault formed by several segments of up to 7 km maximum length favored the uplift of the sierra nevada footwall away from the padul graben hanging wall a non permanent gps network installed in 1999 constrains an average horizontal extensional rate of 0 5 mm yr in n66 e direction the fault length suggests that a maximum 6 magnitude earthquake may be expected but the absence of instrumental or historical seismic events would indicate that fault activity occurs at least partially by creep striae on fault surfaces evidence normal sinistral kinematics suggesting that the padul fault may have been a main transfer fault of the westernmost end of the sierra nevada antiform nevertheless gps results evidence 1 shortening in the sierra nevada antiform is in its latest stages and 2 the present day fault shows normal with minor oblique dextral displacements the recent change in padul fault kinematics will be related to the present day dominance of the ene wsw regional extension versus nnw sse shortening that produced the uplift and northwestwards displacement of sierra nevada antiform this region illustrates the importance of heterogeneous brittle extensional tectonics in the latest uplift stages of compressional orogens as well as the interaction of folding during the development of faults at shallow crustal levels

climatic control on palaeohydrology and cyclical sediment distribution in the plio quaternary deposits of the guadix basin betic cordillera spain abstract a cyclical pattern can be observed in the central sector of the guadix basin southern spain in the late pliocene quaternary alluvial fan deposits prograding into its axial valley a climatic significance has been attributed to this cyclicity on the basis of sedimentological and preliminary isotopic studies the progradation phases of the alluvial fans are here attributed to more arid time intervals in which the vegetation cover would be less developed erosion and sediment supply would be higher and base level would be lower in contrast the time intervals during which the fluvial system sediments dominated the area are inferred to be wetter and base level higher with vegetation cover retaining the soils and preventing erosion permanent water supply to the river would therefore facilitate the aggradation of the floodplain and prevent progradation of the fans starting from a litho bio and magnetostratigraphical frame provided for the area an age is assigned to the alternation of the reddish sediments of the transverse alluvial fans and the greyish to white fluvio lacustrine sediments of the axial drainage system a cyclicity of ca 100 ky has been identified in most of the alluvial fan progradation phases falling within milankovitch high frequency eccentricity periodicities correlation of the phases with insolation curves is accordingly discussed as a possible origin for the cyclicity finally the results offer new insights into early hominin occupation patterns in the region through the identification of predictable resources of permanent fresh water that would have remained available throughout the recorded time span that includes the early middle pleistocene transition even during times of aridification

modeling the evolution of the guadalquivir foreland basin southern spain 1 previous quantitative studies dealing with the origin of foreland basins have focused primarily either on the rheological basis of the lithosphere mechanical response or on the relationship between orogenic loading and sediment geometry to link the evolution of the guadalquivir foreland basin south iberia with the thermomechanical stratification of the iberian lithosphere we combine quantitative approaches to deep and shallow processes thrust loading lithospheric flexure thickness changes of the crust and the lithospheric mantle and surface mass transport a planform flexural analysis of the present day load distribution shows that basement subsidence is related not only to upper crustal thrusting but also to a deep seated additional load on the basis of the observed gravity and geoid fields we propose this additional load to be related to a lithospheric mantle thickening larger than the coeval crustal thickening further modeling of the evolution of a basin cross section reveals that the architecture of the sedimentary basin is additionally related to the lithosphere rheological response the quantitative study of the evolution of basement faulting and the forebulge uplift of sierra morena leads us to conclude that viscous stress relaxation and or plastic yielding within the lithosphere are key processes to explain the flexural evolution of the basin

downslope migrating sandwaves and platform margin clinoforms in a current dominated distally steepened temperate carbonate ramp guadix basin southern spain during the late tortonian platform margin prograding clinoforms developed at the south western margin of the guadix basin large scale wedge shaped deposits here comprise 26 rhythms of mixed carbonate siliciclastic bedset packages and marl beds these sediments were deposited on a shallow water temperate carbonate distally steepened ramp a downslope migrating sandwave field developed in this ramp with sandwaves moving progressively down the ramp to the ramp slope where they destabilized folded and occasionally collapsed downslope sandwave migration was induced by currents flowing basinwards during the late tortonian the guadix basin was open north to the atlantic ocean via the dehesas de guadix strait and connected east to the mediterranean sea through the almanzora corridor according to the proposed current circulation model for the guadix basin for this time surface marine currents from the atlantic entered the basin from the northern seaway these currents moved counter clockwise and shifted the sediment on the ramp forming sandwaves that migrated downslope the development of platform margin prograding clinoforms by the basinward sediment transport mechanisms inferred here is known relatively poorly in the ancient sedimentary record moreover these wedge shaped geometries are similar to those found in some shelves in the western mediterranean sea and could represent an outcrop analogue to sub recent platform margin clinoforms revealed by high resolution seismic studies

recent fault controlled glacis deformation and its role in the fluvial capture of the guadix baza basin betic cordillera southern spain abstract this work is focussed on the geomorphological changes related to the pleistocene capture of the formerly endorheic guadix baza basin betic cordillera we explore the possible tectonic controls in the basin opening through a combined geomorphological and structural study for this we have selected a study area that includes the connecting zone between the former endorheic basin and the capture channel guadiana menor river this zone also includes the se end of the so called tiscar fault zone tfz that has been active during the upper miocene and onwards we use the glacis surface that marks the end of the endorheic sedimentation middle upper pleistocene as the main reference surface to identify recent deformation structures our results indicate that the main channel crossing the pozo alcon glacis guadalentin river shows evidence of high levels of fluvial incision and that some anomalies in the stream longitudinal profile could be correlated to the presence of pre glacis faults linked to the tfz conversely abrupt changes in the stream orientation seems to be related to post glacis downthrow faults we have identified that the dextral strike slip tiscar fault the northern boundary of the tfz propagates towards the se as far as the guadalentin river giving rise to a deformation band with oblique slip that descends the sw block down to 250 m and affects the glacis surface additionally the pozo alcon glacis has undergone distributed deformation mainly achieved by n s to ne sw downthrow faults and subordinate wnw faults the roughly e w extension within the pozo alcon glacis can be interpreted as developed in the extensional lobe at the tip of a dextral strike slip fault the tiscar fault according to the orientation wnw ese and location of the guadiana menor river following the southern boundary of the tfz and the relief attenuation and tilting produced by the extensional systems in the pozo alcon glacis we interpret that the later stages of tfz activity probably controlled and favoured the localisation of the basin capture

active tectonics of the alpine himalayan belt between western turkey and pakistan summary over 80 new fault plane solutions combined with satellite imagery as well as both modern and historical observations of earthquake faulting are used to investigate the active tectonics of the middle east between western turkey and pakistan the deformation of the western part of this region is dominated by the movement of continental material laterally away from the lake van region in eastern turkey this movement helps to avoid crustal thickening in the van region and allows some of the shortening between arabia and eurasia to be taken up by the thrusting of continental material over oceanic type basement in the southern caspian mediterranean makran and black sea thus central turkey bounded by the north and east anatolian strike slip faults is moving west from the van region and overrides the eastern mediterranean at two intermediate depth seismic zones one extending between antalya bay and southern cyprus and the other further west in the hellenic trench the motion of northern iran eastwards from the van region is achieved mainly by a conjugate system of strike slip faults and leads to the low angle thrusting of iran over the southern caspian sea the seismicity of the caucasus shows predominantly shortening perpendicular to the regional strike but there is also some minor elongation along the strike of the belt as the causcasus overrides the caspian and black seas the deformation of the eastern part of this region is dominated by the shortening of iran against the stable borders of turkmenistan and afghanistan the north east direction of compression seen in zagros is also seen in north east iran and the kopet dag where the shortening is taken up by a combination of strike slip and thrust faulting large structural as well as palaeomagnetic rotations are likely to have occurred in ne iran as a result of this style of deformation north south strike slip faults in southern iran allow some movement of material away from the collision zone in ne iran towards the makran subduction zone where genuinely intermediate depth seismicity is seen within this broad deforming belt large areas such as central turkey nw iran azerbaijan central iran and the southern caspian appear to be almost aseismic and therefore to behave as relatively rigid blocks surrounded by active belts 200 300 km wide the motion of these blocks can usefully be described by poles of rotation the poles presented in this paper predict motions consistent with those observed and also predict the opening of the gulf of iskenderun ne of cyprus the change within the zagros mountains from strike slip faulting in the nw to intense thrusting in the se and the relatively feeble seismicity in se iran baluchistan this description also explains why the north south structures along the iran afghanistan border do not cut the east west ranges of the makran within the active belts surrounding the relatively aseismic blocks a continuum approach is needed for a description of the deformation even though motions at the surface may be concentrated on faults the evolution of fault systems within the active zones is controlled by geometric constraints such as the requirement that simultaneously active faults do not in general intersect many of the active processes discussed in this paper particularly large scale rotations and lateral movement along the regional strike are likely to have caused substantial complexities in older mountain belts and should be accounted for in any reconstructions of them

chronology of miocene terrestrial deposits and fossil vertebrates from quebrada honda bolivia abstract at 3500 m above sea level in the eastern andean cordillera quebrada honda basin exposes more than 300 m of middle miocene sedimentary strata developed on distal alluvial fan sediments interstratified with volcanoclastic deposits overlying paleozoic basement these deposits are rich in exotic vertebrate fauna adapted to a wetter and warmer climate at lower paleoelevation as contrasted with the present high elevation cold and dry andean conditions this study provides new magnetostratigraphic and 40ar 39ar age control of the quebrada honda rio rosario and huayllajara fossiliferous areas demonstrating that they are 13 1 12 4 ma part of the succession evidences cyclical deposition of calcretes and reddish mudstones which may be a response to precessional orbital forcing climatic processes paleomagnetic measurements show a significant clockwise tectonic rotation related to postdepositional tectonism associated with evidence of an important uplift after the deposition of quebrada honda sediments this uplift of the andean eastern cordillera was associated with the formation of the subandean fold thrust belt and the development of the amazon and la plata drainage basins proposed uplift rates of 200 m ma are compatible with well established rates of uplift recorded in contemporaneous alpine sections

the baza fault a major active extensional fault in the central betic cordillera south spain in the guadix baza basin betic cordillera lies the baza fault a structure that will be described for the first time in this paper eight gravity profiles and a seismic reflection profile coupled with surface studies indicate the existence of a ne dipping normal fault with a variable strike with n s and nw se segments this 37 km long fault divides the basin into two sectors guadix to the west and baza to the east since the late miocene the activity of this fault has created a half graben in its hanging wall the seismic reflection profile shows that the fill of this 2 000 3 000 m thick asymmetric basin is syntectonic the fault has associated seismicity the most important of which is the 1531 baza earthquake since the late tortonian to the present i e over approximately the last 8 million years extension rates obtained vary between 0 12 and 0 33 mm year for the baza fault being one of the major active normal faults to accommodate the current ene wsw extension produced in the central betic cordillera the existence of this fault and other normal faults in the central betic cordillera enhanced the extension in the upper crust from the late miocene to the present in this regional compressive setting

the 2020 mw 6 8 elazig turkey earthquake reveals rupture behavior of the east anatolian fault the 2020 mw 6 8 elazig earthquake was the largest along the eastern anatolian fault eaf in over a century and so provides valuable insights into its rupture behavior because the eaf is of low to

glacis geometry as a geomorphic marker of recent tectonics the guadix baza basin south spain abstract the guadix baza basin occupies 4000 km 2 and constitutes the largest intramontane basin of the betic cordillera southern spain it has a well preserved geomorphic surface a glacis which started to be eroded when the basin conditions changed from endorheic to exorheic taking into account its large preserved surface area more than 1200 km 2 and its pre deformational geometry this geomorphic surface is a useful marker of recent deformation combining geological and geomorphological data and high resolution dem topographic profiles of the glacis have been produced to estimate vertical displacements caused by active compression and extension structures these structures have produced relative vertical displacements of up to 100 m from the late middle pleistocene to the present assuming an age for the glacis of between 205 and 600 ka it has been possible to estimate long term minimum and maximum vertical rates of the activity of normal faults and folds using this geomorphic surface as a marker vertical slip rates range from 0 07 to 0 49 mm year for the main active normal faults and vertical folding rates range from 0 05 to 0 17 mm year for several active folds these long term vertical slip and folding rates are in accordance with other values previously estimated in other sectors of the betic cordillera when present detailed geomorphic study of recent glacis is an excellent tool for evaluating active tectonics over large regions

sediment supply from the betic rif orogen to basins through neogene abstract we present a quantification of total and partial divided by time slices sedimentary volumes in the neogene basins of the betic rif orogen these basins include the alboran sea the intramontane basins the guadalquivir and rharb foreland basins and the atlantic margin of the gibraltar arc the total volume of neogene sediments deposited in these basins is 209 000 km3 and is equally distributed between the internal alboran basin and intramontane basins and the external basins foreland basins and atlantic margin the largest volumes are recorded by the alboran basin 89 600 km3 and the atlantic margin 81 600 km3 the guadalquivir and rharb basins amount 14 000 km3 and 14 550 km3 respectively whereas the intramontane basins record 9235 km3 calculated mean sediment accumulation rates for the early middle miocene show an outstanding asymmetry between the alboran basin 0 24 mm yr and the foreland basins 0 06 0 07 mm yr and the atlantic margin 0 03 mm yr during the late miocene sedimentation rates range between 0 17 and 0 18 mm yr recorded in the alboran basin and 0 04 mm yr in the intramontane basins in the pliocene quaternary the highest sedimentation rates are recorded in the atlantic margin reaching 0 22 mm yr sedimentary contribution shows similar values for the inner and outer basins with a generalized increase from late miocene to present from 3500 to 6500 km3 my interestingly the alboran basin records the maximum sedimentary contribution during the late miocene 5500 km3 my whereas the atlantic margin does during the pliocene quaternary 6600 km3 my the spatial and time variability of the sediment supply from the betic rif orogen to basins is closely related to the morphotectonic evolution of the region the high sedimentation rates obtained in the alboran basin during the early middle miocene are related to active extensional tectonics which produced narrow and deep basins in its western domain the highest sedimentary contribution in this basin as well as in the foreland and intramontane basins is recorded during the late miocene due to the uplift of wide areas of the betics and rif chains the analysis of the sedimentary supply also evidences strong relationships with the post tortonian crustal thickening and coeval topographic amplification that occurred in the central betics and rif with the concomitant evolution of the drainage network showing the fluvial capture of some internal basins by rivers draining to the atlantic ocean the ancestral guadalquivir

structure and geological history of the carboneras fault zone se spain part of a stretching transform fault system abstract the carboneras fault zone cfz is a major ne sw trending tectonic lineament in se spain active from upper miocene to recent times it separates the volcanic cabo de gata terrain to the se accumulated over 18 6 ma bp from the tract of uplifted alpine metamorphic basement blocks and post orogenic basins that comprise the betic cordilleras lying to the nw new geological mapping and age determinations have been used to constrain the geometry and geological history of the fault zone the cfz consists of left lateral strike slip faults bearing fault gouge formed in the uppermost 5 km of the crust the faults cut metamorphic basement and folded post orogenic sediments and volcanic rocks and acted as a conduit for calc alkaline volcanic rocks rising to the surface nw of the cfz a series of unconformities and deformation episodes affect successive sedimentary formations of upper miocene age the cfz is interpreted as part of a transform fault system separating ne sw stretched and nw se shortened crust deformed above a south westward retreating subducted slab from a less deformed terrain lying to the south east total offset on the cfz may be up to 40 km but is at least 15 km

quaternary landscape evolution and erosion rates for an intramontane neogene basin guadix baza basin se spain abstract the landscape evolution in neogene intramontane basins is a result of the interaction of climatic lithologic and tectonic factors when sedimentation ceases and a basin enters an erosional stage estimating erosion rates across the entire basin can offer a good view of landscape evolution in this work the erosion rates in the guadix baza basin have been calculated based on a volumetric estimate of sediment loss by river erosion since the late pleistocene to do so the distribution of a glacis surface at ca 43 kyr characterised by a calcrete layer that caps the basin infilling has been reconstructed to support this age new radiometric data of the glacis are presented the volume of sediment loss by water erosion has been calculated for the entire basin by comparing the reconstructed geomorphic surface and the present day topography the resulting erosion rates vary between 4 28 and 6 57 m3 ha 1 yr 1 and are the consequence of the interaction of climatic lithologic topographic and tectonic factors individual erosion rates for the guadix and baza sub basins 11 80 m3 ha 1 yr 1 and 1 77 m3 ha 1 yr 1 respectively suggest different stages of drainage pattern evolution in the two sub basins we attribute the lower values obtained in the baza sub basin to the down throw of this sub basin caused by very recent activity along the baza fault

the earthquake of 1546 in the holy landz the earthquake of 1546 is considered to be one of the largest shocks in the middle east associated with surface faulting and great loss of life the examination of contemporary documents shows that this seismic event was a medium magnitude earthquake of ms about 6 0 in many respects similar to that of the earthquake of 1927 that is one of those early and grossly exaggerated events which excited widespread interest rather on account of the geographical location than because of their size or special violence we cpud find no evidence of faulting or excessive damage and no justification to regard this earthquake as one of the most destructive in the jordan rift valley

denudation rates and tectonic geomorphology of the spanish betic cordillera abstract the tectonic control on landscape morphology and long term denudation is largely documented for settings with high uplift rates relatively little is known about the rates of geomorphic response in areas of low tectonic uplift here we evaluate spatial variations in denudation of the spanish betic cordillera based on cosmogenic 10be derived denudation rates denudation rates are compared to published data on rock uplift and exhumation of the betic cordillera to evaluate steady state topography the spatial patterns of catchment wide denudation rates n 20 are then analysed together with topographic metrics of hillslope and channel morphology catchments draining the betic ranges have relatively low denudation rates 64 54 mm kyr 1 but also show large variation as they range from 14 to 246 mm kyr 1 catchment wide denudation is linearly proportional to the mean hillslope gradient and local relief despite large spatial variation in denudation the magnitude and spatial pattern of denudation rates are generally consistent with longer term local uplift rates derived from elevated marine deposits fission track measurements and vertical fault slip rates this might be indicative of a steady state topography where rock uplift is balanced by denudation

widespread landslides induced by the mw 5 1 earthquake of 11 may 2011 in lorca se spain abstract on 11 may 2011 a moderate magnitude mw 5 1 earthquake struck the city of lorca se spain and nearby areas causing notable damage injuries and fatalities field inspection of the area affected allowed the location and characterization of more than 250 induced landslides mainly of disrupted type rock soil falls disrupted soil slides and rock avalanches this number was very high when compared with the inventories of previous events of similar magnitude mw 4 7 to 5 0 in the zone and with the results of previous models for predicting slope behavior during earthquakes several factors are proposed here to explain the observed differences i the comparatively high magnitude mw 4 5 of a foreshock of the seismic series that may have weakened the slopes ii the high peak ground motion values recorded for these events and iii the occurrence of topographic site effects the results of this study point out the importance of including such effects as improvements in the models for studying the regional behavior of slopes

temporary seismic quiescence se turkey summary the border zone that is the contact of the arabian plate with the three plates of turkey eurasia and iran to the north has been remarkably aseismic during this century by extending the period of observation backwards in time by a few centuries it is shown that this seismicity is atypical of the long term behaviour of the zone and due to a quiescent period in the activity of the area during the 20th century in turn this implies that short term data alone do not provide a reliable assessment of earthquake hazard

is the northwestern betic cordillera mountain front active in the context of the convergent eurasia africa plate boundary the present relief of the betic rif cordillera has been mainly developed since the late miocene in the context of the eurasia africa nw se oblique convergence and other interacting processes like slab roll back or delamination however seismicity distribution and field observations reveal that most of the external mountain front of the betics is not clearly active at present and tectonic activity is generally concentrated towards

recent and present day stresses in the granada basin betic cordilleras example of a late miocene present day extensional basin in a convergent plate boundary the diffuse convergent boundary between the eurasian and african plates in the western mediterranean is associated with a seismicity zone more than 300 km wide although the two plates are converging nw se the betic and rif cordilleras contain extensional structures that have been active since the miocene the extensional tectonics in the region which occurred simultaneously with the uplift of the cordillera have been analyzed in the southeastern sector of the late miocene to recent granada basin using earthquake focal mechanisms the determination of paleostresses from the study of the orientation and kinematics of microfaults and the study of the major structures both the geological surface data and the focal mechanisms indicate present day regional conditions of ne sw extension with triaxial to prolate stress ellipsoids however the stress field is heterogeneous with local variations in stress over time with different stresses sometimes even acting simultaneously in adjacent areas the most frequent changes consist of pluridirectional or ne sw extension favored by the prolate character of the stress ellipsoids and nw se subhorizontal compression favored by the regional tectonic setting strike slip faults are scarce even though they are the most likely structure to be expected in a region with sw ne extension and nw se compression seismicity is concentrated in the upper crust and may correspond to the activity of low to high angle normal faults similar to the surface faults although they can not be correlated with them the lower cutoff of this seismicity probably coincides with the 300 c isotherm and suggests a low thermal gradient for the region present day regional stresses have 1 vertical at the surface but in depth plunge toward the sw

nature and impact of the neotectonic deformation in the western sierra nevada spain abstract the current high relief of the western sector of the sierra nevada was practically nonexistent before the tortonian as attested by the marine late neogene outcrops that reach a height of 1830 m which would easily surpass 2000 m if not for erosion the significant uplift produced over 3500 m has caused considerable thinning detachments and gravitational slides in the alpujarride units the general displacements of these movements are towards the wnw to ssw on the whole the morphology is fan like adapting itself to the border of the sierra nevada this border contains normal conjugate nw se and n s to nne ssw faults the latter also with sinistral strike slip character these faults have accommodated the uplift of the sierra nevada within an almost n s compressive context and linked e w extension this sector coincides with the western boundary of the nevado filabride complex and in its southern continuation with the western limit of the lower alpujarride units seeming to indicate a fault or faults reaching deep into the basement uplift has taken place unevenly over the last few million years with three noteworthy periods during the deposition of the block formation in the late tortonian towards the early middle pleistocene and in the middle late pleistocene this has resulted in considerable deepening of the fluvial net surrounding sierra nevada at the present time

geologic evolution of the betic cordilleras in the western mediterranean miocene to the present abstract the betic cordilleras were formed during the eo meso and neo alpine evolution of the western mediterranean area during the neo alpine stage the northward subduction of the african plate took place and the algerian provencal basin opened with the creation of oceanic floor associated space problems produced the expulsion and extensive stretching of the internal zones to the west which in turn disrupted and deformed the external zones of the betic and rif cordilleras these occurrences essentially took place in the burdigalian and continued with diminished intensity into the middle miocene following the suturing of the transcurrent contact between the internal and external zones important n60 90 e and nw se faults occurred the betic cordilleras are characterized as having been deformed by regional horizontal shortening compression oriented wnw ese or nw se which gradually rotated to the nnw sse in the late miocene when its most important intramontane neogene basins were formed the alboran basin with a thinned continental crust was formed as a western prolongation of the opening of the algerian provencal basin with its basic features already apparent in the burdigalian the volcanism present in the southeast of the betic cordilleras and in northeast morocco crossing the alboran basin is mainly late miocene in age it is linked to fracturing and exhibits chemistry related to the different thickness of the crust

the betic segment of the lithospheric trans alboran shear zone during the late miocene abstract the betic sinistral transcurrent shear zone betic cordilleras crosses the southeastern part of spain the study of the geodynamics of this area is approached from tectonic sedimentary magmatic and geophysical data large strike slip movements tectono sedimentary processes and magmatic events are seen at the boundary between two different lithospheric slabs they are located in a thinned compartment with a high geothermal gradient the large scale movements vertical and horizontal and the intensity of magmatic activity are the expression of the mechanical behaviour of this hot and thin crust all the geological events from the late miocene to recent are integrated in a crustal scale cross section which shows that the betic sinistral transcurrent shear zone widely affects the lithosphere it appears that subduction zones are not the only geodynamic context in which calc alkaline magmatism occurs

source inversion of the 1993 and 1995 gulf of aqaba earthquakes abstract the teleseismic body waves of two earthquakes were inverted to their sources so as to obtain a rupture process for each the events of august 3 1993 m s 6 1 and november 22 1995 m s 7 2 took place at the southern end of the dead sea fault system dsfs which has been seismically quiet for the last few centuries the inversion results show that the rupture of the 1995 event originated in the vicinity of the 1993 event and propagated to the north where the major moment release of two subevents took place the first being 20 km and the second being 40 km away the seismic moment of the first and second subevents were m o 7 4 10 18 nm and m o 38 10 18 nm respectively despite their proximity they show completely different focal mechanisms the first subevent has a predominantly normal faulting mechanism like the 1993 event which probably took place on the faults forming the pull apart basins beneath the gulf of aqaba the major subevent shows a predominantly left lateral strike slip mechanism which clearly identifies the dsfs as accommodating the motion between africa and arabia we attribute the abrupt change of the mechanisms of the 1993 and 1995 events to segmentation of the dsfs beneath the gulf of aqaba which probably gave rise to an extensional regime the locations of the 1993 and 1995 earthquakes their aftershock distribution and the spatial distribution of the subevents of the 1995 earthquake show end to end migration of sources from south to north taking into account the long seismic quiescence of the dsfs and the source inversion results one may conclude that the area to the north of the rupture zone of the 1995 event is prone to a large earthquake

clues for a tortonian reconstruction of the gibraltar arc structural pattern deformation diachronism and block rotations abstract we proposed a reconstruction of one of the tightest orogenic arcs on earth the gibraltar arc system this reconstruction which includes onshore and offshore data is completed for approximately 9 ma the clues that lead us to draw it are based on a review in terms of structures and age of the superposed deformational events that took place during miocene with special attention to the external zones this review and new structural data presented in this paper permit us to constrain the timing of vertical axis rotations evidenced by previously published paleomagnetic data and to identify homogeneous domains in terms of relationships between timing of deformation events re magnetization and rotations in particular remagnetization in the betics took place after the main shortening which produced the external fold and thrust belts pre upper miocene but was mostly previous to a contractive reorganization that affected the whole area it should have occurred during lower tortonian between 9 9 and 11 ma from tortonian to present block rotations as high as 53 took place together with plate convergence they accommodated a tightening and lengthening of the gibraltar arc system and drastically altered its geometry as the orientation and position of any pre 9 ma kinematic indicator or structural element is also modified our reconstruction should be used as starting point for any pre tortonian model of the westernmost orogenic segment of the alpine mediterranean system

a reappraisal of the alpine structure of the alpujarride complex in the betic cordillera interplay of shortening and extension in the westernmost mediterranean abstract the alpujarride complex has concentrated discussion on the extent and role of orogenic extension in the betic rif orogen westernmost mediterranean structural analysis on permo triassic rocks of the alpujarride complex is a firm basis to assess extension and to integrate it in the plate tectonic scenario the main alpine deformation was dominated by top to the ne shearing with rare map scale folds as a whole this deformation attests ductile extension during exhumation of previously subducted rocks some authors have suggested that the alpujarride complex continued evolving extensionally since this early exhumation but in this paper a stage of regional shortening is documented thus km scale overturned nw vergent folds are interpreted as witnessing shortening subsequently post metamorphic low angle faults of burdigalian langhian age cut the train of folds in two ways firstly top to the n thrusts generated stratigraphic and metamorphic superpositions then top to the n low angle normal faults kinematically congruent with the thrusts formed due to accretion at deep levels of the orogenic wedge when the nevado filabride complex underthrust the alpujarride complex the shortening stage occurred at latest oligocene early middle miocene and can be related to fast convergence rates between africa and iberia later a drop in the convergent rates prompted lithospheric rollback and top to the sw crustal extension since serravallian time coexisting with moderate orthogonal shortening that gave way to e w trending upright folds

source parameters of large earthquakes in the east anatolian fault zone turkey summary the east anatolian fault zone accommodates most of the motion between the arabian plate and the apparently little deforming interior of central turkey the direction of overall slip across this zone is crucial to the determination of the slip rate on the north anatolian fault we use long period p and sn waveforms to determine the source parameters of the four largest earthquakes that occurred in or near the east anatolian fault zone in the last 35 years only one of these actually involved left lateral strike slip motion on a ne sw fault but the other three and the nearby 1975 lice earthquake all had steeply dipping nodal planes with a nnw strike if these were the auxiliary planes then all the earthquakes had a slip vector direction within about 10 of 063 if this direction represents the arabia turkey motion then the slip rate on the north anatolian fault must be in the range 31 to 48 mm yr with a probable value of 38 mm yr and the overall slip rate across the east anatolian fault zone must be about 29mmyr with a range of 25

block like plate movements in eastern anatolia observed by insar 1 the question whether continental plates deform internally or move as rigid blocks has been debated for several decades to further address this question we use large scale interferometric synthetic aperture radar insar data sets to study how eastern anatolia and its surrounding plates deform we find that most of the deformation is focused at the north and east anatolian faults and little intraplate deformation takes place anatolia is therefore moving at least its eastern part as a uniform block we estimate the slip velocity and locking depth of the north anatolian fault at this location to be 20 mm yr and 14 km respectively high deformation gradient found near the east anatolian fault on the other hand suggests that little stress is accumulating along the eastern sections of that fault

quantitative paleotopography and paleogeography around the gibraltar arc south spain during the messinian salinity crisis abstract the malaga basin contains an important geological record documenting the complex paleogeographic evolution of the gibraltar arc before during and after the closure and desiccation of the mediterranean sea triggered by the messinian salinity crisis msc proxy paleo elevation data estimated from the stratigraphic and geomorphological records allow the building of quantitative paleogeoid paleotopographic and paleogeographic models for the three main paleogeographic stages pre msc tortonian early messinian syn msc late messinian and post msc early pliocene the methodological workflow combines classical contouring procedures used in geology and isobase map models from geomorphometric analyses and proxy data overprinted on present digital terrain models the resulting terrain quantitative models have been arranged managed and computed in a gis environment the computed terrain models enable the exploration of past landscapes usually beyond the reach of classical geomorphological analyses and strongly improve the paleogeographic and paleotopographic knowledge of the study area the resulting models suggest the occurrence of a set of uplifted littoral erosive and paleokarstic landforms that evolved during pre msc times these uplifted landform assemblages can explain the origin of key elements of the present landscape such as the torcal de antequera and the large amount of mogote like relict hills present in the zone in terms of ancient uplifted tropical islands the most prominent landform is the extensive erosional platform dominating the betic frontal zone that represents the relic atlantic wave cut platform elaborated during late tortonian to early messinian times the amount of uplift derived from paleogeoid models suggests that the area rose by about 340 m during the msc this points to isostatic uplift triggered by differential erosional unloading towards the mediterranean as the main factor controlling landscape evolution in the area during and after the msc former littoral landscapes in the old emergent axis of the gibraltar arc were uplifted to form the main water divide of the present betic cordillera in the zone

the regional time and magnitude predictable model and its application to the alpine himalayan belt abstract the regional time and magnitude predictable model has been introduced and has been shown to be appropriate to describe the behaviour in the occurrence of mainshocks the model implies that the magnitude of the preceding mainshock in a seismogenic region that is the largest earthquake during a seismic excitation governs the time of occurrence and the magnitude of the expected mainshock in this region this model has been applied in 149 seismogenic regions of the alpine himalayan seismic belt the model probability for the occurrence of the next very strong main shock ms 6 5 during the decade 1993 2002 as well as the magnitude of this shock in each of these regions have been calculated furthermore two tests have been performed to check the validity of this model these tests have shown the reliability of the model and its superiority compared to the classical time independent model

stress accumulation and increased seismic risk in eastern turkey abstract unlike the north anatolian fault zone which has produced 11 large earthquakes since 1939 the east anatolian fault zone eafz has been relatively quiescent in the last century when compared to historical records and has therefore accumulated significant stresses along its length determination of the location and likely magnitude of a future probable earthquake along the eafz is of interest both because of this history of large earthquakes m 8 and the density of population in the area here we calculate stress evolution along the fault zone due to both seismic and tectonic loading since 1822 a sequence of 10 well constrained historical earthquakes is selected and the resulting stresses are calculated summed with tectonic loading stresses and resolved onto the mapped active faults we identify two areas of particular seismic risk one of which might be expected to yield a large event our results are sensitive to the previous history of large earthquakes in the region and indicate a need for detailed investigations to constrain the exact rupture geometries of previous earthquakes on these segments

smooth folds favoring gypsum precipitation in the messinian poniente marginal basin western mediterranean abstract the poniente basin lies in a folded sector located at the boundary between the eastern betic cordillera and the alboran sea we reconstruct its 3d geometry combining depth migrated 2d seismic reflection sections with borehole and surface structural data the folds have been interplaying with sedimentation since late miocene time growth strata allow us to reconstruct both the folding history and the average shortening rate two isolated antiforms began to grow during the late tortonian separated by an antiformal saddle point a rectilinear fold linkage sector between initially isolated short segments developed during the messinian eventually forming a subcylindrical ene wsw trending antiform that has continued growing symmetrically since the pleistocene the antiform formed a barrier that favored messinian evaporite deposition along the contiguous synform to the north the vertical breakup between the lower parts of the synform and the barrier anticline culmination ranges from 500 to 700 m in the last 7 2 ma the analyzed folds accommodated a shortening of 52 m ma along a 20 km wide band at a mediterranean scale our study sheds light on the propagation mode of barriers that favor the precipitation of gypsum in peripheral basins by restricting water exchange with the open sea before the main phase of evaporite deposition occurred in the deep basin