timing kinematics and cause of aegean extension a scenario based on a comparison with simple analogue experiments abstract since the early 1970s most geodynamic models proposed for the eastern mediterranean consider that the initiation of extension in the aegean during the late middle miocene or later was a direct consequence of the westward extrusion of anatolia away from the arabia eurasia collision front in the late 1990s a few models have taken into account the increasing evidence for an earlier initiation of aegean extension arising mostly from the analysis of deformation within the various alpine metamorphic complexes of the area based largely on our own investigations we first present a review of the data that reliably constrain the minimum age for the initiation of extension in these complexes it shows that regional scale extension with a pattern of stretching orientations similar to that of the pliocene pleistocene was already strongly active in the aegean before the onset of arabian indentation into eurasia lower miocene vs middle or upper miocene this implies that the initiation of aegean extension did not result from the lateral extrusion of anatolia instead extension may have started owing to a process of gravity spreading of the continental lithosphere that had previously been thickened during alpine collision the main arguments favouring this interpretation are presented and a preliminary scenario is proposed for the neogene evolution of the eastern mediterranean in which lateral extrusion of anatolia occurred lately during southward spreading of the aegean lithosphere in order to test this hypothesis further physical experiments simulating the horizontal spreading of a continental lithosphere toward a free boundary have been carried out the analysis of various elements of the deformation field displacements strain rotations fault pattern and kinematics both in the experiments and in the aegean domain reveals an excellent agreement between the two not only do early stages of aegean extension appear to fit the gravity spreading hypothesis but so does the recent to present internal deformation of the aegean transverse e w active shortening observed in the northern aegean is commonly taken as one of the most striking pieces of evidence that aegean extension results from the lateral extrusion of anatolia the experiments indicate that such transverse shortening may equally develop as a result of pure gravity spreading associated with a pattern of faults and rotations that compares well with that of the northern aegean pure dextral shearing along some strands of the north aegean trough fault system and the related development of an asymmetric pattern of faults in the northern aegean are eventually the only features that evidently arise from the extrusion of anatolia since less than 3 ma finally we argue that during the early stages of aegean extension since at least 21 ma and until ca 11 ma the distribution of extensional strain on a regional scale has been controlled by the distribution of earlier thickening post thickening thermal weakening through partial melting of deep levels of the crust probably accounts for the localization of extensional strain within the areas of thick crust restoring the aegean in its most likely configuration at the onset of bulk crustal extension suggests that 1 the extensional strain rate remained roughly constant or has eventually decreased since the onset of aegean extension and 2 the amounts of extension before and after 16 ma have been roughly equal

global positioning system measurements of present day crustal movements in the arabia africa eurasia plate collision zone we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1994 at 54 sites extending east west from the caucasus mountains of southern russia georgia and armenia to the aegean coast of turkey and north south from the southern edge of the eurasian plate pontus block to the northern edge of the arabian platform viewed from a eurasia fixed reference frame sites on the northern arabian platform move n38 13 w at 20 3 mm yr roughly consistent with the velocity implied by nuvel 1a circuit closure n23 7 w at 24 2 mm yr the motion of arabia appears to be transferred directly to the region of turkey north of the suture however eastern turkey is characterized by distributed deformation while central western turkey is characterized by coherent plate motion involving westward displacement and counterclockwise rotation of the anatolian plate internal deformation within the central part of the anatolian plate is less than 2 mm yr the anatolian plate is decoupled from eurasia along the right lateral strike slip north anatolian fault naf this different response in eastern and western turkey to the collision of arabia may result from the different boundary conditions the hellenic arc forming a free boundary to the west and the asian continent and oceanic lithosphere of the black and caspian seas forming a resistant boundary to the north and east we derive a best fitting euler vector for anatolia eurasia motion of 29 2 0 8 n 32 9 0 4 1 3 0 1 m y the mapped surface trace of the naf corresponds well to a small circle about this pole the new euler vector implies an upper bound for naf slip rate of 30 2 mm yr i e assuming all relative motion is accommodated along the naf using the nuvel 1a euler vector for arabia eurasia and the gps euler vector for anatolia eurasia we determine an arabia anatolia euler vector of 31 2 n 45 2 e 0 9 0 1 m y and an upper bound on the east anatolian fault slip rate of 15 3 mm yr the aegean trough region of western turkey deviates significantly from coherent plate rotation in addition to rotating with anatolia this region shows roughly n s extension at a rate of 14 5 mm yr taken together with satellite laser ranging results along the hellenic arc the contemporary pattern of deformation indicates increasing motions toward the arc suggesting that the westward displacement and counterclockwise rotation of anatolia is driven both by pushing from the arabian plate and by pulling or basal drag associated with the foundering african plate along the hellenic subduction zone

impact of hellenic arc tsunamis on corsica france in the historical period the eastern mediterranean has been devastated by several tsunamis the two most damaging were those of ad 365 and ad 1303 generated by great earthquakes of magnitude 8 at the hellenic plate boundary recently events of 6 7 magnitude have occurred in this region as the french tsunami warning center has to ensure the warning for the french coastlines the question has raised the possibility for a major tsunami triggered along the hellenic arc to impact the french coasts the focus is on the corsica coasts especially to estimate what would be the expected wave heights and from which threshold of magnitude it would be necessary to put the population under cover this study shows that a magnitude 8 0 earthquake nucleated along the hellenic arc could induce in some cases a tsunami that would be observed along the corsica coasts and for events of 8 5 magnitude amplitudes exceeding 50 cm can be expected which would be dangerous in harbors and beach areas especially the main contribution of these results is the establishment of specific thresholds of magnitude for the tsunami warning along the french coasts 7 8 for the advisory level coastal marine threat with harbors and beaches evacuation and 8 3 for the watch level inland inundation threat for tsunamis generated along the hellenic arc

the north cycladic detachment system and associated mineralization mykonos greece insights on the evolution of the aegean domain 1 in the aegean back arc domain some 30 35 ma ago an increase of the rate of slab retreat led to the initiation of post orogenic extension largely accommodated by large scale structures such as the north cycladic detachment system ncds although this extension is still active nowadays an e w compressional regime developed in the late miocene with the propagation of the north anatolian fault on mykonos island cyclades the ne sw back arc extension is particularly well expressed with the livada and mykonos detachments that belong to the ncds and that are associated with nw se barite veins emplaced during the synkinematic cooling of the mykonos intrusion this study shows that the formation of the mineralization occurred when the pluton crossed the ductile to brittle transition during its exhumation below the ncds at 11 10 ma in addition the kinematics of mineralized structures evolved with time 1 most of the displacement was accommodated by the top to the ne livada and mykonos detachments accompanied by the formation of mineralized normal faults that were 2 reworked in a strike slip regime with an e w direction of shortening and a persistent ne sw stretching and 3 a late post mineralization e w compressional stage with a minor reworking of shallow dipping faults locally including the detachments themselves we interpret this increase of the e w shortening component recorded during the mineral deposition as a consequence of the initiation of the westward motion of anatolia from 10 ma thus 4 ma before the propagation of the north anatolian fault in the dardanelles strait and the localization of the strain on the aegean sea margins

differentiation conditions of a basaltic magma from santorini and its bearing on the production of andesite in arc settings santorini volcano in the aegean region greece is characterized by andesitic to silicic dominated explosive activity and caldera forming eruptions sourced from magmatic reservoirs located at various structural levels beneath the volcano there is a good understanding of the silica rich magmatism of the island whereas the andesite dominated volcanism and the petrogenesis of the parental mafic magmas are still poorly understood to fill this gap we have performed crystallization experiments on a representative basalt from santorini with the aim of determining the conditions of differentiation pressure temperature volatile fugacities and the parental magma relationship with the andesitic eruptive rocks experiments were carried out between 975 and 1040 c in the pressure range 100 400 mpa fo2 from qfm to nno 3 5 where qfm is quartz fayalite magnetite and nno is nickel nickel oxide with h2omelt contents varying from saturation to nominally dry conditions the results show that basalt phenocrysts within the basalt crystallized at around 1040 c in a magma storage reservoir located at a depth equivalent to 200 400 mpa pressure with 3 5 wt dissolved h2o and fo2 around qfm comparison with the xenocryst and phenocryst assemblages of the upper scoria 1 andesite shows that andesitic liquids are produced by fractionation of a similar basalt at 1000 c and 400 mpa following 60 80 wt crystallization of an ol cpx plag ti mag opx 6 pig ilm assemblage with melt water contents around 4 6 wt at santorini the andesitic low viscosity and water rich residual liquids produced at these depths segregate from the parent basaltic mush and feed the shallow magma reservoirs eventually erupting upon mixing with resident magma changes in prevailing oxygen fugacity may control the tholeiitic calc alkaline character of santorini magmas explaining the compositional and mineralogical differences observed between the recent thyra and old eruptive products from akrotiri

plio quaternary stress state in the burdur basin sw turkey abstract this study defines the plio quaternary to present day stress regime in the burdur basin located at the northeastern end of the fethiye burdur fault zone in sw turkey this fault length which is considered the landward continuation of the pliny strabo trench is an important feature in sw turkey the inversion slip vectors measured on fault planes indicate a consistent normal faulting stress regime during plio quaternary time continuing into recent times as indicated by earthquake focal mechanism inversions both states have consistent nw se trending horizontal minimum stress axes 3 the orientation of fault sets is predominantly around the ne sw direction in the major fethiye burdur fault zone making the extension nw se the mean stress ratio is 0 74 indicating a triaxial stress state which is clearly different from radial extension the nw se extension is probably responsible for the formation of the burdur basin during plio quaternary time this extension which is probably caused by slab pull force due to the subduction process along the cyprus arc produces a dominant normal motion along the fbfz

effect of compaction pressure on consolidation behaviour of unsaturated silty soil the effect of compaction pressure on subsequent soil behaviour during isotropic consolidation has been investigated by conducting controlled suction triaxial tests on samples of an unsaturated compacted silty soil a comprehensive set of laboratory experiments was carried out in a double walled triaxial apparatus on samples of unsaturated soil that were prepared using two different compaction pressures the axis translation technique was used for creating the desired suctions in the samples in the experiments the soil samples were subjected to isotropic consolidation under constant suctions the results show that different compaction pressures produce different fabrics in a soil and therefore affect the behaviour of the soil the results also show that the value of yield stress and the location of the loading collapse lc yield curve are functions of soil fabric furthermore it is shown that the slopes of normal consolidation lines for densely and loosely compacted samples differ in unsaturated condit

crustal investigation of the hellenic subduction zone using wide aperture seismic data abstract we present the results of a wide aperture seismic onshore offshore study crete seismic experiment in the cretan region as part of the hellenic arc compressional system three seismic lines were carried out on and around the island of crete in order to investigate the crustal structure of the region up to 119 three component recording stations were deployed on each profile that observed seismic energy generated by a 48 l airgun array and eight 20 kg landshots a total of 6208 shots were fired upon completing the fieldwork the vertical components of all stations were evaluated 300 common receiver gather crg sections of the ocean bottom seismographs obs and land stations as well as 100 common source gather csg sections of the land shots and selected airgun shots were compiled and modeled in order to generate a 2d p wave velocity depth model for each profile the accuracy of the model depends on the depth and position along the profiles and does not exceed 5 for both depth and p wave velocity we identified strong lateral variations in crustal and sedimentary thickness mainly in a north south direction but also along strike east west the crust is continental and has a maximum thickness of 32 5 km below northern central crete its subdivision in an upper v p 5 8 6 3 km s locally up to 6 5 km s and a lower v p 6 4 6 9 km s part is justified by a first order discontinuity with v p velocity a contrast of up to 0 6 km s the eastern part of crete shows a significantly thinner crust of 24 to 26 km to the north the crustal thickness decreases to 15 km below the central cretan sea the prominent decrease of the moho depth north of central crete is interpreted to represent the northern end of a microcontinent that was subducted in oligocene times and later surfaced by buoyant escape stockhert et al 1999 thomson et al 1999 the p t t d history of the high pressure rocks of crete greece denudation by buoyant escape in exhumation processes normal faulting ductile flow and erosion ring u lister g willet s brandon m eds spec publ of the geol soc of london p 154 to the south and southwest of the island the continental crust gradually thins to a minimum of 17 km and at approximately 100 km off the southern coast of crete it is in contact with oceanic crust below the mediterranean ridge upper mantle velocities were determined to be 7 7 km s below the cretan sea and 8 0 km s south of crete below the continental cretan crust a 6 to 7 km thick layer with v p velocities between 6 6 and 7 1 km s was identified on each line and could be followed by reflections to a depth of 42 km it is decoupled from the overlying continental crust at central crete and is interpreted as oceanic crust presently under subduction towards the nne below the aegean sea

tectonic motion and deformation from satellite laser ranging to lageos satellite laser ranging slr to lageos acquired during the period 1978 1988 has been analyzed to yield estimates of tectonic motion for 22 laser tracking stations situated on seven major plates the analysis is based on the precise modeling of the orbit dynamics of lageos and includes the determination of other geodynamic and nonconservative force model parameters involved in the orbit determination problem at the centimeter level site velocities were recovered from station positions determined each calendar quarter using a network adjustment procedure which maintains the reference frame within the stable interior of tectonic plates the recovered motions indicate good agreement with existing estimates of stress fields particularly across northern europe the eastern pacific and in the basin and range province of north america a comparison of the intersite motions for stations centrally located on separate plates between slr and those implied by the nuvel 1 geologic motion model yield a strong positive correlation of 0 989 and a 3 7 scale difference which may be attributable to recent changes in relative velocities or geologic time scale uncertainties sites located at or within 250 km of convergent plate boundaries have additional components of motion indicating a need for further tectonic modeling beyond that provided by simple rigid plate motions for lines crossing the north atlantic the san andreas fault and within the basin and range province the geodesic rates determined by slr are in good agreement with those determined by very long baseline interferometry an alternative space geodetic technique

aegean tectonics strain localisation slab tearing and trench retreat abstract we review the geodynamic evolution of the aegean anatolia region and discuss strain localisation there over geological times from late eocene to present crustal deformation in the aegean backarc has localised progressively during slab retreat extension started with the formation of the rhodope metamorphic core complex eocene and migrated to the cyclades and the northern menderes massif oligocene and miocene accommodated by crustal scale detachments and a first series of core complexes mccs extension then localised in western turkey the corinth rift and the external hellenic arc after messinian times while the north anatolian fault penetrated the aegean sea through time the direction and style of extension have not changed significantly except in terms of localisation the contributions of progressive slab retreat and tearing basal drag extrusion tectonics and tectonic inheritance are discussed and we favour a model 1 where slab retreat is the main driving engine 2 successive slab tearing episodes are the main causes of this stepwise strain localisation and 3 the inherited heterogeneity of the crust is a major factor for localising detachments the continental crust has an inherited strong heterogeneity and crustal scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation the dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate successive slab ruptures from the middle miocene to the late miocene have isolated a narrow strip of lithosphere still attached to the african lithosphere below crete the formation of the north anatolian fault is partly a consequence of this evolution the extrusion of anatolia and the aegean extension are partly driven from below asthenospheric flow and from above extrusion of a lid of rigid crust

the m w 6 7 12 october 2013 western hellenic arc main shock and its aftershock sequence implications for the slab properties the 12 october 2013 m w6 7 earthquake offshore crete island is one of the few strong earthquakes to have occurred in the last few decades in the southwestern part of the hellenic subduction zone hsz providing the opportunity to evaluate characteristics of the descending slab the hsz has experienced several strong m 7 0 earthquakes in historical times with the largest one being the 365 ad m w 8 4 earthquake the largest known ever occurred in the mediterranean region the 2013 main shock occurred in close proximity with the 365 event on an interplate thrust fault at a depth of 26 km onto the coupled part of the overriding and descending plates gcmt solution shows a slightly oblique rake 130 thrust faulting with downdip compression on a nearly horizontal dip 3 northeast dipping fault plane with strike 340 parallel to the subduction front with the compression axis being oriented in the direction of plate convergence the subduction interface can be more clearly resolved with the integration of aftershock locations and cmt solution for this scope the aftershocks were relocated after obtaining a v p v s ratio equal to 1 76 a one dimensional velocity model and time delays that approximate the velocity structure of the study area and the employment of double difference technique for both phase pick data and cross correlation differential times the first day relocated seismicity alike aftershocks in the first 2 months shows activation of an area at the upper part of the descending slab with most activity being concentrated between 13 and 27 km where the main shock is also encompassed aftershocks are rare near to the main shock implying homogeneous slip on a large patch of the rupture plane based on the aftershock distribution the size of the activated area estimated is about 24 km long and 17 km wide coulomb stress changes resolved for transpressive motion reveal negligible off fault aftershock triggering evidencing a comparatively stable regime in the downdip part of the slab or different fault mechanism

active faulting at the western tip of the gulf of corinth greece from high resolution seismic data abstract the gulf of corinth is one of the fastest spreading intra continental rifts on earth gps data indicate that the rift is currently opening in a nne ssw direction with a rate of extension reaching up to 16 mm yr 1 in its westernmost part although the rest of the offshore rift has been well studied the western tip of the rift is still poorly explored we present an accurate map of submarine faults in this area based on two high resolution seismic reflection surveys single channel sparker in the eastern part of the studied area the sedimentary infill is affected by the known north eratini south eratini and west channel faults further to the west the seafloor is mostly flat and is bounded to the north by the normal south dipping trizonia fault to the north the shallower part of the gulf shows to the east a diffuse pattern of normal and strike slip deformation which is replaced to the west by a 7 5 km long se striking strike slip fault zone called the managouli fault zone to the westernmost tip of the gulf in the nafpaktos basin two fault sets with different strikes are encountered the one with a ne sw strike exhibits a clear strike slip component the western tip of the gulf of corinth is the only part of the corinth rift where convincing evidence for strike slip movement has been found this fault pattern is likely related to the complex deformation occurring at the diffuse junction at the western tip of the rift between three crustal blocks continental greece peloponnese and the ionian island akarnania block

slip partitioning in the sea of marmara pull apart determined from gps velocity vectors summary dislocation modelling is used to examine the gps velocity vectors for the marmara sea region first the vectors due to the known anatolia eurasia rotation are reproduced by introducing structures that approximate the large scale tectonics observed features of the smaller scale fault system in the marmara region are then progressively included with slip amplitudes and directions adjusted to fit an 80 vector subset of the gps data the motion in the marmara sea region is partitioned with the faults that bound the north of the basin carrying more strike slip motion than predicted from the anatolia eurasia plate motion and faults to the south having a greater perpendicular component taken together however there is no net opening across the marmara sea perpendicular to the overall trend of the boundary and thus deformation in the marmara region results only from the pull apart geometry of the north anatolian fault no extension related to the aegean system is needed to explain the observations the gps results are consistent with motion over the last 5 myr that has been determined from geological reconstructions

present day kinematics of the middle east and eastern mediterranean the middle east and eastern mediterranean regions contain three major strike slip fault zones the dead sea fault zone dsfz and the north and east anatolian fault zones nafz and eafz these accommodate northward motion of the african and arabian plates relative to eurasia and westward motion of the small turkish plate this study deduces an internally consistent solution for the present day kinematics of these plates which is accurate to better than 20 and applicable throughout time since 5 ma by constraining the slip senses and rates on these strike slip fault zones the 7 0 5 mm yr 1 left lateral slip rate on the dsfz is associated with counterclockwise rotation of arabia relative to africa at 0 33 m y 1 around an eulcr pole near 33 n 23 e the nafz takes up counterclockwise rotation of the turkish plate relative to eurasia at 0 83 m y 1 13 around a pole at 31 n 35 5 e with right lateral slip rate 15 mm yr 1 the resulting prediction for the eafz involves 14 mm yr 1 left lateral motion and 2 mm yr 1 of shortening between arabia and turkey the triple junction of africa arabia and turkey is near the city of kahramanmaras this locality contains a narrow promontory bounded by ssw trending left lateral faults at the edges of the arabian and turkish plates which is loosely attached to the african plate moving westward relative to its interior at 4 mm yr 1

gps derived strain rate field within the boundary zones of the eurasian african and arabian plates we use the gps velocity field 1988 1998 for eastern mediterranean and asia minor to determine the crustal deformation strain rate field in an area bounded by 35 n and 43 n and 20 e and 48 e we calculate the normal and shear strain rate components associated with the major faults and compare these qualitatively with seismological data uncertainties in the calculation of the strain rates reach 50 nstrain yr 1 in sparsely observed parts of anatolia whereas we estimate errors 20 nstrain yr 1 in the aegean and marmara regions the largest compressional strain rate components in the eastern part of the study area occur along the greater caucasus mountain front reaching 70 nstrain yr 1 1 nstrain yr 1 0 0317 10 15 s 1 the north anatolian fault zone is the clearest feature in the shear strain rate field it is expressed as a pronounced dextral strike slip fault zone reaching rates of up to 170 nstrain yr 1 this holds true also for the izmit area where the august 17 1999 earthquake occurred central anatolia is almost strain free whereas extension prevails in western anatolia the principal axes of extension vary around the n s direction with strain rates of up to 85 nstrain yr 1 these extensional areas coincide with graben features and normal faulting earthquakes the central and southwestern aegean sea is strain free with values far below 40 nstrain yr 1 the seismic cluster around the dodekanissa islands southeastern aegean sea coincides with nw se oriented extension attaining strain rates of up to 90 nstrain yr 1 this area of extension also exhibits recent active volcanism the entire hellenic arc shows compressional strain rates perpendicular to the arc the pliny strabo troughs along the eastern segment of the arc show left lateral shear strain rates reaching 80 nstrain yr 1 significant extension is found in central greece with a nne ssw oriented maximum of 120 nstrain yr 1 centered around the gulf of corinthos the kephalonia fault zone in nw greece is a distinct dextral fault zone separating apulia from the rapidly moving aegean microplate right lateral shear strain rates reach 150 nstrain yr 1

difference in the gps deformation pattern of north and central zagros iran summary measurements on either side of the kazerun fault system in the zagros mountain belt iran show that the accommodation of the convergence of the arabian and eurasian plates differs across the region in northwest zagros the deformation is partitioned as 3 6 mm yr 1 of shortening perpendicular to the axis of the mountain belt and 4 6 mm yr 1 of dextral strikeslip motion on northwest southeast trending faults no individual strike slip fault seems to slip at a rate higher than 2m m yr 1 in southeast zagros the deformation is pure shortening of 8 2m m yr 1 occurring perpendicular to the simple folded belt and restricted to the persian gulf shore the fact that most of the deformation is located in front of the simple folded belt close to the persian gulf while seismicity is more widely spread across the mountain belt confirms the decoupling of the surface sedimentary layers from the seismogenic basement a comparison with the folding and topography corroborates a southwestward propagation of the surface deformation the difference in deformation between the two regions suggests that right lateral shear cumulates on the north south trending kazerun strike slip fault system to 6 2m m yr 1

the tectonic expression slab pull at continental convergent boundaries examination of five thrust belt systems developed at continental subduction boundaries suggests that they comprise two distinct groups that display pronounced and systematic differences in structural style topographic elevation denudation metamorphism postcollisional convergence and foredeep basin geometry and facies the distinctive geological features developed within each thrust belt group appear to be causally linked to the relative rates of subduction and convergence via the magnitude of horizontal compressional stress transmitted across the subduction boundary at subduction boundaries where the rate of overall plate convergence is less than the rate of subduction termed here retreating subduction boundaries the transmission of horizontal compressive stress across the plate boundary is small and regional deformation of the overriding plate is by horizontal extension the tectonic expression of these retreating subduction boundaries includes topographically low mountains little erosion or denudation low grade to no metamorphism little to no involvement of crystalline basement in shortening little to no postcollisional convergence anomalously deep foredeep basins and a protracted history of flysch deposition within the adjacent foredeep basin analysis of deflection and gravity data across three retreating subduction boundaries apennine carpathian and hellenic systems shows that subduction is driven by gravitational forces acting on dense subducted slabs at depths between about 40 and 80 km carpathians 50 and 150 km apennines and 50 and 250 km hellenides the total mass anomalies represented by the slabs are approximately 3 1012 6 1012 and 12 1012 n m respectively the slabs are partially supported by flexural stresses transmitted through the subducted lithosphere to the foreland and partially supported by dynamic viscous stresses in the asthenosphere at subduction boundaries where the rate of overall plate convergence is greater than the rate of subduction termed here advancing subduction boundaries the transmission of horizontal compressive stress across the plate boundary is large and regional deformation of the overriding plate is by horizontal shortening the tectonic expression of these advancing subduction boundaries includes topographically high mountains antithetic thrust belts large amounts of erosion and denudation exposure of high grade metamorphic rocks at the surface extensive deformation of crystalline basement to midcrustal depths protracted postcollisional convergence tens of millions of years and a protracted history of molasse deposition within the adjacent foredeep basins analysis of gravity and deflection data across two advancing subduction boundaries developed within the continental lithosphere western to eastern and southern alps and himalayas shows that the thrust sheets have been translated for great distances over the foreland lithosphere relative to the point at which the subduction forces are applied thus obscuring any flexural and gravity signals from the subducted slab however it appears that far field stresses presumably related to global plate motions drive most of the convergent motion across these subduction boundaries the concept that orogenic belts formed above retreating subduction boundaries have recognizable tectonic signatures that differ from those of orogenic belts formed above advancing subduction boundaries suggests that it may be possible to interpret the plate boundary settings in which ancient orogenic belts evolved appendix b is available with entire article on microfiche order from the american geophysical union 2000 floridaavenue n w washington d c 20009 document t92 004 2 50 payment must accompany order

the north anatolian fault in the sea of marmara 1 using the detailed geometry and tectonics of the main marmara fault that connects the gulf of izmit fault with the ganos fault established by le pichon et al 2001 and the new gps data set recently analyzed by meade et al 2002 we confirm the existence of a marmara block delimited to the north by the northern branch of the north anatolian fault the marmara branch and to the south by the southern branch the kinematics of this block indicate that the marmara branch that crosses the sea of marmara is close to pure dextral strike slip at a rate of 23 mm yr on its whole length the short cinarcik section is the only one where a significant extensional component is predicted a simple kinematic model accounts for slip partitioning there with 8 10 mm yr of extension to the south of the basin and 23 mm yr of dextral strike slip along the northern cinarcik margin the new gps data demonstrate the existence of important asymmetric elastic loading along the main marmara fault that may have significant implications for the seismotectonics of the area the expected future large earthquake may rupture the whole main marmara fault the partitioning in the cinarcik basin may produce magnitude 7 normal faulting earthquakes if their repetition time is about 250 years the 1896 earthquake may have been one of these normal fault earthquakes the marmara block is less than 1 ma prior to its formation it was part of the anatolian block at this time the ganos fault was already a dextral strike slip fault but the fault system in the sea of marmara would have been affected by an extensional component increasing toward the east that accounts for the increasing size of the sedimentary basins eastward

seismicity of the hellenic subduction zone in the area of western and central crete observed by temporary local seismic networks temporary local seismic networks were installed in western crete in central crete and on the island gavdos south of western crete respectively in order to image shallow seismically active zones of the hellenic subduction zone more than 4000 events in the magnitude range between 0 5 and 4 8 were detected and localized the resulting three dimensional hypocenter distribution allows the localization of seismically active zones in the area of western and central crete from the mediterranean ridge to the cretan sea furthermore a three dimensional structural model of the studied region was compiled based on results of wide angle seismics surface wave analysis and receiver function studies the comparison of the hypocenter distribution and the structure has allowed intraplate and interplate seismicity to be distinguished high interplate seismicity along the interface between the subducting african lithosphere and the aegean lithosphere was found south of western crete where the interface is located at about 20 to 40 km depth an offset between the southern border of the aegean lithosphere and the southern border of active interplate seismicity is observed in the area of crete the offset varies laterally along the hellenic arc between about 50 and 70 km a southwards dipping zone of high seismicity within the aegean lithosphere is found south of central crete in the region of the ptolemy trench it reaches from the interface between the plates at about 30 km depth towards the surface in comparison the aegean lithosphere south of western crete is seismically much less active including the region of the ionian trench intraplate seismicity within the aegean plate beneath crete and north of crete is confined to the upper about 20 km between 20 and 40 km depth beneath crete the aegean lithosphere appears to be seismically inactive in western crete the southern and western borders of this aseismic zone correlate strongly with the coastline of crete

tearing segmentation and backstepping of subduction in the aegean new insights from seismicity abstract this study revisits subduction processes at the hellenic subduction zone hsz including tearing segmentation and backstepping by refining the geometry of the nubian slab down to 150 180 km depth using well located hypocentres from global and local seismicity catalogues at the western termination of the hsz the kefalonia transform fault marks the transition between oceanic and continental lithosphere subducting to the south and to the north of it respectively a discontinuity is suggested to exist between the two slabs at shallow depths the kefalonia transform fault is interpreted as an active subduction transform edge propagator fault formed as consequence of faster trench retreat induced by the subduction of oceanic lithosphere to the south of it a model reconstructing the evolution of the subduction system in the area of peloponnese since 34 ma involving the backstepping of the subduction to the back side of adria provides seismological evidence that supports the single slab model for the hsz and suggests the correlation between the downdip limit of the seismicity to the amount of subducted oceanic lithosphere in the area of rhodes earthquake hypocentres indicate the presence of a nw dipping subducting slab that rules out the presence of a ne sw striking subduction transform edge propagator fault in the pliny strabo trenches region earthquake hypocentres also allow refining the slab tear beneath southwestern anatolia down to 150 180 km depth furthermore the distribution of microseismicity shows a first order slab segmentation in the region between crete and karpathos with a less steep and laterally wider slab segment to the west and a steeper and narrower slab segment to the east thermal models indicate the presence of a colder slab beneath the southeastern aegean that leads to deepening of the intermediate depth seismicity slab segmentation affects the upper plate deformation that is stronger above the eastern slab segment and the seismicity along the interplate seismogenic zone

westward propagation of the north anatolian fault into the northern aegean timing and kinematics we present new evidence for the propagation processes of the north anatolian fault folding in the dardanelles straits region allows us to document the timing of the deformation preceding and the finite displacement after the passage of the propagating tip of the fault the accuracy of the observations is due to interplay between deformation and the sea level changes in the mediterranean the well known messinian regression followed by the pliocene transgression the long term kinematics around the sea of marmara pull apart total displacement of about 85 km over the past 5 m y is similar to the present day kinematics deduced from space geodesy at a larger scale westward propagation of the north anatolian fault over nearly 2000 km in the past 10 m y appears to be associated with strain recovery suggesting that the continental lithosphere retains long term elasticity

effects of margin parallel shortening and density contrasts on back arc extension during subduction experimental insights and possible application to anatolia so as to investigate the parameters influencing subduction and back arc extension we have done three series of laboratory experiments 32 in all on physical models each model consisted of adjacent oceanic and continental plates floating on an asthenosphere in experiments of series a a wide rigid piston moving horizontally controlled the rate of convergence of the oceanic and continental plates whereas in series b or c a wide or narrow piston produced lateral compression parallel to the continent ocean boundary cob and perpendicular to the subduction direction the parameters that we tested were 1 the velocity of plate convergence series a 2 the width of the compressing piston series b and c and 3 the density ratio between oceanic and continental plates series b and c this density ratio was a key factor for a ratio of 1 4 the amount of extension in the continental plate increased regularly throughout time for a ratio of 1 3 the extension remained small until the piston stopped moving laterally and for a ratio of 1 1 there was little or no extension the width of the compressing piston had a smaller effect although a narrow piston provided more space into which the continental plate could extend one possible application of our models is to anatolia despite similar geological settings the areas north of the hellenic and cyprus subduction zones differ in that extension is large in the former and much smaller in the latter we suggest that one of the main driving forces for aegean extension may have been a high density ratio between subducting oceanic lithosphere and a hellenic balkanic upper plate

global plate velocities from the global positioning system we have analyzed 204 days of global positioning system gps data from the global gps network spanning january 1991 through march 1996 on the basis of these gps coordinate solutions we have estimated velocities for 38 sites mostly located on the interiors of the africa antarctica australia eurasia nazca north america pacific and south america plates the uncertainties of the horizontal velocity components range from 1 2 to 5 0 mm yr with the exception of sites on the pacific and nazca plates the gps velocities agree with absolute plate model predictions within 95 confidence for most of the sites in north america antarctica and eurasia the agreement is better than 2 mm yr we find no persuasive evidence for significant vertical motions 3 standard deviations except at four sites three of these four were sites constrained to geodetic reference frame velocities the gps velocities were then used to estimate angular velocities for eight tectonic plates absolute angular velocities derived from the gps data agree with the no net rotation nnr nuvel 1a model within 95 confidence except for the pacific plate our pole of rotation for the pacific plate lies 11 5 west of the nnr nuvel 1a pole with an angular speed 10 faster our relative angular velocities agree with nuvel 1a except for some involving the pacific plate while our pacific north america angular velocity differs significantly from nuvel 1a our model and nuvel 1a predict very small differences in relative motion along the pacific north america plate boundary itself our pacific australia and pacific eurasia angular velocities are significantly faster than nuvel 1a predicting more rapid convergence at these two plate boundaries along the east pacific rise our pacific nazca angular velocity agrees in both rate and azimuth with nuvel 1a

late holocene slip rate for the north anatolian fault turkey from cosmogenic 36cl geochronology implications for the constancy of fault loading and strain release rates geomorphologic mapping and cosmogenic radionuclide 36cl dating of an offset fluvial terrace yield a preferred late holocene slip rate of 20 5 5 5 mm yr for the central part of the north anatolian fault turkey an independent slip rate constrained by 14c ages is 20 5 8 5 mm yr these rates are generally similar to but possibly slightly slower than the short term rate of elastic strain storage of 25 1 measured geodetically across this major strike slip fault reilinger et al 2006 1 suggesting that loading and strain release on this part of the north anatolian fault have been relatively constant when averaged over the past 2 2 5 k y we attribute this consistency to the relatively simple structure of the anatolia eurasia plate boundary in north central turkey where almost all plate boundary strain is accommodated along the north anatolian fault the absence of other moderate to high slip rate faults and the earthquakes they produce leads to a relatively simple stress evolution for the fault dominated by steady tectonic loading 1 ref 10

an integrated global model of present day plate motions and plate boundary deformation summary in this paper we present a global model gsrm 1 of both horizontal velocities on the earth s surface and horizontal strain rates for almost all deforming plate boundary zones a model strain rate field is obtained jointly with a global velocity field in the process of solving for a global velocity gradient tensor field in our model we perform a least squares fit between model velocities and observed geodetic velocities as well as between model strain rates and observed geological strain rates model velocities and strain rates are interpolated over a spherical earth using bi cubic bessel splines we include 3000 geodetic velocities from 50 different mostly published studies geological strain rates are obtained for central asia only and they are inferred from quaternary fault slip rates for all areas where no geological information is included a priori constraints are placed on the style and direction but not magnitude of the model strain rate field these constraints are taken from a seismic strain rate field inferred from normalized focal mechanisms of shallow earthquakes we present a global solution of the second invariant of the model strain rate field as well as strain rate solutions for a few selected plate boundary zones generally the strain rate tensor field is consistent with geological and seismological data with the assumption of plate rigidity for all areas other than the plate boundary zones we also present relative angular velocities for most plate pairs we find that in general there is a good agreement between the present day plate motions we obtain and longterm plate motions but a few significant differences exist the rotation rates for the indian arabian and nubian plates relative to eurasia are 30 13 and 50 per cent slower than the nuvel1a estimate respectively and the rotation rate for the nazca plate relative to south america is 17 per cent slower on the other hand caribbean north america motion is 76 per cent faster than the nuvel 1a estimate while crustal blocks in the india eurasia collision zone move significantly and self consistently with respect to bounding plates only a very small motion is predicted between the nubian and somalian plates by integrating plate boundary zone deformation with the traditional modelling of angular velocities of rigid plates we have obtained a model that has already been proven valuable in for instance redefining a no net rotation model of surface motions and by confirming a global correlation between seismicity rates and tectonic moment rates along subduction zones and within zones of continental deformation

continental transforms a view from the alpine fault abstract continental transform faults are dominantly highly localized strike slip shear zones hundreds of kilometers long that accumulate tens to hundreds of kilometers of displacement from work on the alpine fault we pose the questions what is the deep structure of a continental transform and how does the displacement become localized we review research on the alpine fault and propose a model in which the fault partitions at depth into a steep zone extending into the mantle with largely fault parallel motion and a flat ductile decollement in the lower crust the fault localizes around two thirds of the plate motion within a 100 km wide zone of distributed deformation a review of other active continental fault systems suggests that variation between them may reflect their tectonic origins the nature of the crust in which they develop the presence of a significant oblique component of motion and the displacement rate all however have evidence for the development of a single principal fault zone that carries 50 of the total displacement and extends as a localized zone of shear into the upper mantle we review mechanisms of strain weakening and suggest that localization of a principal fault may be initiated in the seismogenic crust and through a series of positive feedbacks eventually extend through the lower crust into the upper mantle

the 10 june 2012 fethiye mw 6 0 aftershock sequence and its relation to the 24 25 april 1957 ms 6 9 7 1 earthquakes in sw anatolia turkey abstract the 10 june 2012 mw 6 0 aftershock sequence in southwestern anatolia is examined centroid moment tensors for 23 earthquakes with moment magnitudes mw between 3 7 and 6 0 are determined by applying a waveform inversion method the mainshock is a shallow focus strike slip with reverse component event at a depth of 30 km the seismic moment mo of the mainshock is estimated as 1 28 1018 nm and rupture duration of the fethiye mainshock is 38 s the focal mechanisms of the aftershocks are mainly strike slip faulting with a reverse component the geometry of the focal mechanisms reveals a strike slip faulting regime with ne sw trending direction of t axis in the entire activated region a stress tensor inversion of focal mechanism data is performed to obtain a more accurate picture of the fethiye earthquake stress field the stress tensor inversion results indicate a predominant strike slip stress regime with a nw se oriented maximum horizontal compressive stress sh according to variance of the stress tensor inversion to first order the fethiye earthquake area is characterized by a homogeneous interplate stress field the coulomb stress change associated with the mainshock and the largest aftershock are also investigated to evaluate any significant enhancement of stresses along the gulf of fethiye and surrounding region positive lobes with stress more than 0 4 bars are obtained indicating that these values are large enough to increase the coulomb stress failure towards nnw sse and e w directions

a miocene onset of the modern extensional regime in the isparta angle constraints from the yalvac basin southwest turkey the pre neogene tauride fold and thrust belt comprising cretaceous ophiolites and metamorphic rocks and non metamorphic carbonate thrust slices in southern turkey is flanked and overlain by neogene sedimentary basins these include poorly studied intra montane basins including the yalvac basin in this paper we study the stratigraphy sedimentology and structure of the yalvac basin which has a middle miocene and younger stratigraphy our results show that the basin formed as a result of multi directional extension with ne sw to e w extension dominating over subordinate nw se to n s extension we show that faults bounding the modern basin also governed basin formation with proximal facies close to the basin margins grading upwards and basinwards into lacustrine deposits representing the local depocentre the yalvac basin was a local basin but a similar contemporaneous history recently reconstructed from the altinapa basin 100 km to the south shows that multi directional extension dominated by e w extension was a regional phenomenon extension is still active today and we conclude that this tectonic regime in the study area has prevailed since middle miocene times previously documented e w shortening in the isparta angle along the aksu thrust 100 km to the southwest of our study area is synchronous with the extensional history documented here and e w extension to its east shows that anatolian westwards push is likely not the cause synchronous e w shortening in the heart and e w extension in the east of the isparta angle may be explained by an eastwards dipping subduction zone previously documented with seismic tomography and earthquake hypocentres we suggest that this slab surfaces along the aksu thrust and creates e w overriding plate extension in the east of the isparta angle neogene and modern anatolian geodynamics may thus have been driven by an aegean antalya and cyprus slab segment that each had their own specific evolution

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

crustal motion and deformation in greece from a decade of gps measurements 1993 2003 abstract the hellenic plate boundary region located in the collision zone between the nubian arabian and eurasian lithospheric plates is one of the seismo tectonically most active areas of europe during the last 15 years gps measurements have been used to determine the crustal motion in the area of greece with the aim to better understand the geodynamical processes of this region an extended reoccupation network covering whole greece has been measured periodically in numerous gps campaigns since the late eighties and a continuous gps network has been operated in the region of the ionian sea since 1995 in this paper we present a new detailed high quality solution of continuous and campaign type measurements acquired between 1993 and 2003 during the gps processing a special effort was made to obtain consistent results with highest possible accuracies and reliabilities data of 54 mainly european igs and euref sites were included in the gps processing in order to obtain results which are internally consistent with the european kinematic field and order to allow for a regional interpretation after an overview of the results of the igs euref sites the results from more than 80 stations in greece are presented in terms of velocities time series trajectories and strain rates previous geodetic geological and seismological findings are generally confirmed and substantially refined new important results include the observation of deformation zones to the north and to the south of the north aegean trough and in the west hellenic arc region arc parallel extension of about 19 mm yr along the hellenic arc and compression between the ionian islands and the greek mainland due to continuous long term observations of 4 8 years it was possible to extract height changes from the gps time series in greece we observe a differential subsidence of the order of 2 mm yr between the northern and central ionian islands across the kefalonia fault zone the differential subsidence of the central ionian islands with respect to the northwestern greek mainland amounts to 4 mm yr

earthquake swarms slow slip and fault interactions at the western end of the hellenic subduction system precede the mw 6 9 zakynthos earthquake greece the month to year long deformation of the earth s crust where active subduction zones terminate is poorly explored here we report on a multidisciplinary dataset that captures the synergy of slow s

eastern mediterranean tectonics and tsunami hazard inferred from the ad 365 earthquake historical accounts describe an earthquake and tsunami on 21 july ad 365 that destroyed cities and drowned thousands of people in coastal regions from the nile delta to modern day dubrovnik the location and tectonic setting of this earthquake have been uncertain until now here we present evidence from radiocarbon data and field observations that western crete was lifted above sea level by up to 10 m synchronously with the ad 365 earthquake the distribution of uplift combined with observations of present day seismicity suggest that this earthquake occurred not on the subduction interface beneath crete but on a fault dipping at about 30 within the overriding plate calculations of tsunami propagation show that the uplift of the sea floor associated with such an earthquake would have generated a damaging tsunami through much of the eastern mediterranean measurement of the present rate of crustal shortening near crete yields an estimate of 5 000 yr for the repeat time of tsunamigenic events on this single fault in western crete but if the same process takes place along the entire hellenic subduction zone such events may occur approximately once every 800 yr in the year ad 365 an earthquake and tsunami destroyed much of the eastern mediterranean coastal regions the distribution of uplift at the time suggests that the earthquake occurred on a fault within the overriding plate at the subduction zone beneath crete and not on the subduction interface itself

gps constraints on africa nubia and arabia plate motions summary we use continuously recording gps cgps and survey mode gps sgps observations to determine euler vectors for relative motion of the african nubian arabian and eurasian plates we present a well constrained eurasia nubia euler vector derived from 23 igs sites in europe and four cgps and three sgps sites on the nubian plate 0 95 4 8 n 21 8 4 3 e 0 06 0 005 myr 1 we see no significant 1m m yr 1 internal deformation of the nubian plate the gps nubian eurasian euler vector differs significantly from nuvel 1a 21 0 4 2 n 20 6 0 6 e 0 12 0 015 myr 1 implying more westward motion of africa relative to eurasia and slower convergence in the eastern mediterranean the arabia eurasia and arabia nubia gps euler vectors are less well determined based on only one cgps and three sgps sites on the arabian plate the preliminary arabia eurasia and arabia nubia euler vectors are 27 4 1 0 n 18 4 2 5 e 0 40 0 04 myr 1 and 30 5 1 0 n 25 7 2 3 e 0 37 0 04 myr 1 respectively the gps arabia nubia euler vector differs significantly from nuvel 1a 24 1 1 7 n 24 0 3 5 e 0 40 0 05 myr 1 but is statistically consistent at the 95 per cent confidence level with the revised euler vector reported by chu gordon based on a re evaluation of magnetic anomalies in the red sea 31 5 1 2 n 23 0 2 7 e 0 40 0 05 myr 1 the motion implied in the gulf of aqaba and on the dead sea fault dsf by the new gps nubia arabia euler vector i e ignoring possible sinai block motion and possible internal plate deformation grades from pure left lateral strike slip in the gulf and on the southern dsf with increasing compression on the central and northern dsf with relative motion increasing from 5 6 to 7 5 mm yr 1 1m m yr 1 from south to north along the northern dsf i e north of the lebanon restraining bend motion is partitioned between 6 1m m yr 1 left lateral motion parallel to the fault trace and 4 1m m yr 1 faultnormal compression relative motions on other plate boundaries including the anatolian and aegean microplates derived from the gps euler vectors agree qualitatively with the sense of motion indicated by focal mechanisms for large crustal earthquakes m 6 where data are available on fault slip rates on plate bounding faults north anatolian fault east anatolian fault dead sea fault red sea rift they are generally lower than but not significantly different from the full plate motion estimates suggesting that the majority of relative plate motion is accommodated on these structures

geodetic constraints on the tectonic evolution of the aegean region and strain accumulation along the hellenic subduction zone article i nfo we present evidence that gps velocity estimates of plate motions and fault slip rates agree to within uncertainties with geologic estimates during the most recent phase of the geologic evolution of the e mediterranean region post late miocene on this basis we use the gps differential velocities to estimate the timing of initiation of the principal structures in nw turkey the n aegean sea and central greece including the marmara sea the gulfs of evia goe and corinth goc and the kephalonia transform fault ktf we interpret these ages to indicate that the north anatolian fault propagated across the n aegean opening the goe and goc and initiating the ktf during the past 1 4 ma we further suggest that aegean extension that was earlier more distributed across the aegean basin became focused on this new fault system allowing the southern aegean and peloponnisos to translate sw with little internal deformation as observed today with gps this change in tectonic configuration may account for the clear geologic evidence for crustal thinning throughout the s aegean in apparent contradiction with low present day strain rates we further show that the low present day strain rate along the southern edge of the aegean micro plate requires substantial aseismic slip along the plate interface below crete consistent with the low level of historic subduction type earthquakes along this segment of the subduction zone

alkali feldspars as a main phosphorus reservoirs in rare metal granites three examples from the bohemian massif czech republic phosphorus rich alkali feldspars were found in three peraluminous highly differentiated albite topaz li mica granites in the w and s parts of the bohemian massif the average contents of p2o5 in k feldspars k i ovy kamen 0 57 wt homolka 0 77 wt and podlesi 0 83 wt are higher than the average contents of p2o5 in albites k i ovy kamen 0 23 wt homolka 0 23 wt and podlesi 0 39 wt the analyses of feldspars indicate that partition coefficient of phosphorus between k feldspar and albite range from 1 5 to 2 5 measured data in k feldspars suggest a statistically significant difference from the al3 p5 2 si4 substitution mechanism for higher phosphorus concentration the p content in k feldspars from the podlesi granite represent the highest p content in natural feldspar known to date up to 2 5 wt of p2o5 it is suggested that all studied granites retained nearly all phosphorus of granitic melts and that their alkali feldspars represent major reservoirs of phosphorus

current plate motions across the red sea summary a new objective method is used to estimate precisely 64 rates of seafloor spreading since chron 2a 3 2 ma from all the red sea magnetic profiles available from 15 9 to 26 n the fastest spreading rate 16 mm yr 1 occurs near 18 n whereas the slowest rate 10 mm yr 1 occurs at 25 5 n and is consistent with the rate predicted from arabia nubia data to the south the standard deviation of the spreading rates is 0 8 mm yr 1 much smaller than the median standard deviation of 4 mm yr 1 previously assigned to spreading rates in the global plate motion model nuvel 1 demets et al 1990 the fit to the spreading rates as well as the locations of earthquakes in and near the red sea indicate that spreading south of approximately 17 7 n is less than the full rate of spreading between the arabian and nubian plates the red sea spreading centre is instead usefully interpreted as the boundary between the arabian plate and a danakil microplate that includes the subaerial danakil block and a larger oceanic portion of lithosphere despite the absence of reliable azimuths of transform faults in the red sea all components of the angular velocity of arabia relative to nubia are usefully constrained from just the 45 relevant spreading rates the new compact 95 per cent confidence region of the angular velocity excludes prior estimates based on only four and two spreading rates by chase 1978 and jestin et al 1994 respectively 19 spreading rates in the southern red sea are used to estimate the angular velocity between the danakil microplate and arabia an approach based on singular value decomposition shows that without slip vectors only two of the three components of the angular velocity of the danakil microplate relative to arabia or nubia are usefully constrained but that all three components are usefully constrained if one earthquake slip vector is included

map view restoration of aegean west anatolian accretion and extension since the eocene 1 the aegean region greece western turkey is one of the best studied continental extensional provinces here we provide the first detailed kinematic restoration of the aegean region since 35 ma the region consists of stacked upper crustal slices nappes that reflect a complex paleogeography these were decoupled from the subducting african adriatic lithospheric slab especially since 25 ma extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes we reconstruct up to 400 km of trench perpendicular ne sw extension in two stages from 25 to 15 ma the aegean forearc rotated clockwise relative to the moesian platform around euler poles in northern greece accommodated by extensional detachments in the north and an inferred transfer fault se of the menderes massif the majority of extension occurred after 15 ma up to 290 km by opposite rotations of the western and eastern parts of the region simultaneously the aegean region underwent up to 650 km of post 25 ma trench parallel extension leading to dramatic crustal thinning on crete we restore a detachment configuration with the mid cycladic lineament representing a detachment that accommodated trench parallel extension in the central aegean region finally we demonstrate that the sakarya zone and cretaceous ophiolites of turkey cannot be traced far into the aegean region and are likely bounded by a pre 35 ma n s fault zone this fault became reactivated since 25 ma as an extensional detachment located west of lesbos island the paleogeographic units south of the izmir ankara sava suture however can be correlated from greece to turkey

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates the arabia eurasia collision deforms an area of 3 000 000 km2 of continental crust making it one of the largest regions of convergent deformation on earth there are now estimates for the active slip rates total convergence and timing of collision related deformation of regions from western turkey to eastern iran this paper shows that extrapolating the present day slip rates of many active fault systems for 3 7 million years accounts for their total displacement this result means that the present kinematics of the arabia eurasia collision are unlikely be the same as at its start which was probably in the early miocene 16 23 ma or earlier in some but not all active fault systems short term 10 year and long term 5 million year average deformation rates are consistent there is little active thickening across the turkish iranian plateau and possibly the interior of the greater caucasus these are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening and where there are structural and or stratigraphic data for pre late miocene deformation we suggest that once thick crust up to 60 km built up in the turkish iranian plateau and the greater caucasus convergence took place more easily by crustal shortening in less elevated regions such as the zagros simple folded zone the south caspian region and foothills of the greater caucasus or in other ways such as westward transport of turkey between the north and east anatolian faults the time and duration of this changeover are not known for certain and are likely be diachronous although deformation started or intensified in many of the currently active fault systems at 5 2 ma

the rare earth element geochemistry on surface sediments shallow cores and lithological units of lake acigol basin denizli turkey abstract the sediments in lake acigol located in sw anatolia turkey were formed under tectono sedimentary events ree geochemical investigations of the lake acigol sediments from surface and shallow core sediments at different depths 0 10 cm 10 20 cm and 20 30 cm are presented to clarify the characteristics of ree and the nature of source rocks in the lake sediments and to deduce their paleoenvironmental proxies the chondrite normalized ree patterns of these sediments are shown as light enrichment in lree and flat hree with a negative eu anomaly that is close to the continental collision basin ccb in its profile this is not comparable with paas and ucc inorganic detrital materials control the ree characteristics of the lake acigol sediments and these sediments were accumulated in oxic and dysoxic depositional conditions and or at passive margins derived from oceanic island arc rocks they were affected by low chemical weathering either at the original source or during transport before deposition under arid or subtropical humid climatic conditions in addition we used gis techniques such as inverse distance weighted idw and geographically weighted regression gwr to investigate the spatial interpolation and spatial correlation of the rees from the lake surface sediments in lake acigol and its surrounding lithological units gis techniques showed that the lithological units e g hayrettin formation north of lake acigol have high ree contents however eu eu values were higher in some lake surface sediments than in lithological units and that refers to a negative eu anomaly therefore lake acigol sediments are derived from the weathered products mainly from local highly basic bedrock around the lake from the archean crust the chronology of lake acigol sediment was conducted using the constant rate of supply crs model using the crs methods for the calculation of sedimentation rate we obtained a 0 012 g cm 2 year value which is an average value for the first 20 cm depth of this lake the core activity profiles of 210 pb and 137 cs were measured to estimate the age of the sediments we observed activities of 8 08 5 5 bq kg for 210 pb and 0 86 0 6 bq kg for 137 cs

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

strike slip fault geometry in turkey and its influence on earthquake activity the geometry of turkish strike slip faults has been reviewed and described from this data set it appears that fault geometry the distribution of discontinuities such as bends and stepovers along the main fault trace plays an important role in controlling the location of large earthquake rupture segments along the fault zones large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30 more important than the size of each discontinuity however is the total geometric pattern i e the distribution of adjacent bends and stepovers based not only on distance from one another but also on relative discontinuity size certain geometric patterns restraining single or double bends are particularly common and can be viewed as responsible for strain accumulation along portions of the fault zone fault geometry not only plays a role in the extent of earthquake rupture but also in characteristics of earthquake behavior for example large earthquake epicenters often occur near restraining bends or double bends furthermore aftershocks and swarm activity can often be associated with releasing areas areas along the strike slip fault that are undergoing a relatively large amount of extension

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

seismicity of the 24 may 2014 mw 7 0 aegean sea earthquake sequence along the north aegean trough abstract the northern aegean sea was hit by a large size mw 7 0 earthquake on 2014 may 24 centroid moment tensor solutions for 40 events with moment magnitudes mw between 3 3 and 7 0 are computed by applying a waveform inversion method on data from the turkish and greek broadband seismic networks the time span of data covers the period between 2014 may 24 and 2014 june 26 the mainshock is a shallow focus strike slip event at a depth of 15 km focal depths of aftershocks range from 6 to 30 km the seismic moment mo of the mainshock is estimated as 4 60 1019 nm the calculated rupture duration of the north aegean sea mainshock is 40 s the focal mechanisms of the aftershocks are mainly strike slip faulting with a minor normal component the geometry of focal mechanisms reveals a strike slip faulting regime with ne sw trending direction of t axis in the entire activated region a stress tensor inversion of focal mechanism data is performed to acquire a more accurate picture of the northern aegean sea stress field along the north aegean trough the stress tensor inversion results indicate a predominant strike slip stress regime with a nw se oriented maximum principal compressive stress 1 in the development of the north aegean trough in aegean sea is in good agreement with the resolved stress tensors with respect the newly determined focal mechanisms the effect of the propagating of the north anatolian fault into aegean sea is very clearly pronounced according to high resolution hypocenter relocation of the north aegean sea seismic sequence three main clusters are revealed the aftershock activity in the observation period between 2014 may 24 and 2014 july 31 extends from the mainshock cluster from ne to the sw direction seismic cross sections indicate that a complex pattern of the hypocenter distribution with the activation of seventeen segments the eastern cluster is associated with a fault plane trending mainly ene wsw and dipping vertical while the western is related to a fault plane trending ne sw and dipping towards nnw the best constrained focal depths indicate that the aftershock sequence is mainly confined in the crust depth 30 km and is operating in the approximate depth range from 1 5 to 30 km consequently coulomb stress analysis is performed to calculate the stress transfer and correlate it with the activated region positive lobes with stress more than 3 bars are obtained indicating that these values are large enough to increase the coulomb stress failure towards ene wsw direction

active tectonics of the aegean region the aegean sea and its surrounding regions comprise one of the most rapidly deforming parts of the alpine himalayan mountain belt though the deformation of the belt as a whole is related to thc northward move ment of africa arabia and india relative to eurasia the tectonics of the aegean region itself is dominated by strike slip and extensional motions the actively deforming part of the aegean region is not large about 700 x 700 km2 compared with that in asia yet it has had an influence on our views of continental tectonics disproportionate to its size and comparable perhaps only to tibet fundamental contributions from the aegean have been made to many topics including