late glacial and holocene vegetation and climate variability including major droughts in the sky lakes region of southeastern new york state abstract sediment cores from lakes minnewaska and mohonk in the shawangunk mountains of southeastern new york were analyzed for pollen plant macrofossils macroscopic charcoal organic carbon content carbon isotopic composition carbon nitrogen ratio and lithologic changes to determine the vegetation and landscape history of the greater catskill mountain region since deglaciation pollen stratigraphy generally matches the new england pollen zones identified by deevey 1939 and davis 1969 with boreal genera picea abies present during the late pleistocene yielding to a mixed pinus quercus and tsuga forest in the early holocene lake minnewaska sediments record the younger dryas and possibly the 8 2 cal kyr bp climatic events in pollen and sediment chemistry along with an 1400 cal yr interval of wet conditions increasing tsuga and declining quercus centered about 6400 cal yr bp both minnewaska and mohonk reveal a protracted drought interval in the middle holocene 5700 4100 cal yr bp during which pinus rigida colonized the watershed lake levels fell and frequent fires led to enhanced hillslope erosion together the records show at least three wet dry cycles throughout the holocene and both similarities and differences to climate records in new england and central new york drought intervals raise concerns for water resources in the new york city metropolitan area and may reflect a combination of enhanced la nina negative phase nao and positive phase pna climatic patterns and or northward shifts of storm tracks

microseismicity in the region of tehran we record and analyze small earthquakes around tehran iran using the permanent seismological network of the institute of geophysics of the university of tehran and two temporary dense seismological networks installed for several weeks during 1999 and 2000 regional seismicity is distributed throughout central alborz extending from the caspian sea to the iran plain with the highest level of activity east of tehran related to the mosha and to the garmsar faults which both dip northward and have had strong historical earthquakes our focal mechanisms the first for these faults confirm a left lateral strike slip motion

size distribution of parkfield s microearthquakes reflects changes in surface creep rate s u m m a r y the nucleation area of the series of m6 events in parkfield has been shown to be characterized by low b values throughout the seismic cycle since low b values represent high differential stresses the asperity structure seems to be always stably stressed and even unaffected by the latest main shock in 2004 however because fault loading rates and applied shear stress vary with time some degree of temporal variability of the b value within stable blocks is to be expected we discuss in this study adequate techniques and uncertainty treatment for a detailed analysis of the temporal evolution of b values we show that the derived signal for the parkfield asperity correlates with changes in surface creep suggesting a sensitive time resolution of the b value stress meter and confirming near critical loading conditions within the parkfield asperity

morphological pedological and sedimentary evolution on the fringe of the southwestern european drylands during the late pleistocene and holocene evidence of climate and land use changes abstract late quaternary alluvial sedimentary units in the guadiana menor river valley a tributary of the guadalquivir river in southern spain are described based on geomorphological mapping sedimentological analysis palaeosol development and radiocarbon chronology four infill units in the valleys were differentiated with surfaces at 45 mu1 70 mu2 8 6 mu3 and 10 m mu4 above the riverbed each unit is capped by a palaeosol unit mu1 late pleistocene 43 5 34 cal kyr bp consists of gravel and sand in channels and bars in braided river systems distally evolving to silty clays in the floodplain with vertic and clayic calcisols it is capped by dark clays with gleysol development representing wetland environments in endorheic basins channelized gravels alternating with sandy silts make up unit mu2 34 24 cal kyr bp capped by a gypsisol and interpreted as a semi arid alluvial fan distally evolving to playa lake depositional systems unit mu3 5600 2700 cal yr bp extending along the valley bottom is represented by gravels and sand distally evolving to a red and white laminated rhythmite of silt and clay deposited in the playa unit mu4 600 700 cal yr bp is scattered and represented by centimetre thick gravels and sand sheet layers deposited by sheet flows in semi arid constrained alluvial fans alternating intervals of alluvial aggradation 43 5 24 kyr bp 5700 2700 cal yr bp late middle ages and fluvial incision 24 6 cal kyr bp 2700 cal yr bp to 1200 ad 1500 ad to present are interpreted as valley responses to climate variations and changes in land use two regional geomorphological changes are recorded in the sediments 1 climate induced aridification after 34 cal kyr bp with an arid climax after 24 cal kyr bp before the incision linked to the last glacial period and 2 two human forced aggradation stages 5600 2700 cal yr bp and 1200 1400 ad interrupting the late pleistocene to early holocene incisional trend

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

contributions of la nina and el nino to middle holocene drought and late holocene moisture in the american southwest eolian landforms in estancia basin central new mexico record two episodes of extreme drought and low groundwater levels during the middle holocene 7000 5400 1 4 c yr b p followed by a rise in the water table throughthe late holocene blowouts and associated lunettes formed when water levels fell below the desiccated floor of pluvial lake estancia allowing widespread deflation elevation of the water table in the basin is regulated by a balance between evaporation from playas that occupy the blowouts and recharge of aquifers in the adjacent manzano mountains isotopic analyses of modern precipitation and groundwater reveal that recharge originates primarily as winter moisture which is amplified during el ninos and diminished during la ninas thus changes in the elevation of a reconstructed holocene water table may reflect systematic changes in el nino southern oscillation enso circulation

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

direct chronometry 14c ams of the earliest copper metallurgy in the guadalquivir basin spain during the third millennium bc first regional database abstract the characterisation of copper metallurgy in the third millennium bc in the southeast of the iberian peninsula as a simple and technological process on a domestic scale was the central axis that sustained a belated underdeveloped appreciation for the prehistory of the iberian peninsula and western europe dependent on the origin of social complexities nevertheless this characterisation was incomplete since it was based more on the contexts of consumption than those of production and in territories used for agricultural rather than for mining purposes above all however it was incomplete because it lacked a precise spatial and temporal framework that evaluated the variability of the behaviours it articulated to overcome these deficiencies we have developed a systematic programme of interdisciplinary research aimed at documenting and dating through the use of 14 c ams the direct contexts of copper production of eight settlements that cover the populational variability from 300 to 0 25 ha of surface area chronology between c 3000 bc and c 2000 bc economic settlements dedicated to mining agriculture etc and territorial along the axis of the backbone of the most fertile soils and primary main supplies of copper in the iberian peninsula the guadalquivir basin results consist of the first systematic database with sixty six precise direct radiocarbon dating of the metallurgical production of copper during the third millennium bc in the iberian peninsula and western europe at the same time it presents a variability of contexts e g household workshop partial time full time factory smelting quarter etc in both time and space affording a precise evaluation of social and territorial variability of behaviours that the production of copper shows us a new historical explanation and the link between this and the development of social complexity

effect of soil conditions on predicted ground motion case study from western anatolia turkey abstract we present a site effect study for the city of izmir western anatolia turkey local amplification was evaluated using state of practice tools ten earthquakes recorded at 16 sites were analysed using spectral ratios relative to a reference site horizontal to vertical spectral ratios and an inversion scheme of the fourier amplitude spectra of the recorded s waves seismic noise records were also used to estimate site effects the different estimates are in good agreement among them although a basic uncertainty of a factor of 2 seems difficult to decrease we used our site effect estimates to predict ground motion in izmir for a possible m6 5 earthquake close to the city using stochastic modelling site effects have a large impact on psv pseudospectral velocity where local amplification increases amplitudes by almost a factor of 9 at 1 hz relative to the firm ground condition our results allow identifying the neighbourhoods of izmir where hazard mitigation measurements are a priority task and will also be useful for planning urban development

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

an assessment of the microseismic activity and focal mechanisms of the izmir smyrna area from a new local network izmirnet abstract izmir metropolitan area is one of the biggest cities of turkey in terms of population and industrial density amount of recordings and quality of located events increased since the new local seismic array izmirnet was installed in 2008 present study addresses to elucidate seismotectonics of izmir vicinity by a new data set and reveal first results of seismological analysis obtained for 4 5 years 930 small earthquakes are well located within less than 1 0 km horizontal error rms 0 15 s over a total of 1421 recorded events data were processed by using seisan earthquake analysis software implemented at seismolab of dokuz eylul university the orhanli tuzla fault zone and izmir faults are capable of producing a destructive earthquake events show clear clusters around the outer bay of izmir gulf and sigacik bay we also detected some dense clusters sigacik bay to the south and in the outer bay of izmir gulf along nw se direction we investigated kinematics of active faults around the izmir and foca areas by using 41 focal mechanism solutions from different algorithms foca is located 60 km in the nw direction of izmir mechanisms generally resulted in pure normal or dominant normal faulting with minor strike slip components in agreement with the kinematics of the other fault zones in western turkey a stress tensor study using selected fault plane solution indicates that the study area is under extension regime in an n s direction with 71 plunge for maximum compressive principal stress axis s1 and closer to horizontals for intermediate s2 and minimum compressive principal stress axis s3

the effectiveness of a distant accelerometer array to compute seismic source parameters the april 2009 l aquila earthquake case history the 6 april 2009 mw 6 3 l aquila earthquake central italy has been recorded by the irpinia seismic network isnet about 250 km southeast of the epicenter up to 19 three component accelerometer stations could be used to infer the main source parameters with different seismological methods we obtained an approximate location of the event from arrival times and array based back azimuth measurements and estimated the local magnitude 6 1 from an at tenuation relation for southern italy assuming an omega square spectral model we inverted s wave displacement spectra for moment magnitude 6 3 corner frequency 0 33 hz stress drop 2 5 mpa and apparent stress 1 6 mpa waveform modeling using a point source and an extended source model provided consistent moment tensors with a centroid depth around 6 km and a prevalently normal fault plane solution with a dominant directivity toward the southeast the relatively high corner frequency and an overestimated moment magnitude of 6 4 from moment tensor inversions are attributed to the rupture directivity effect to image the rupture geometry we implemented a beamforming technique that back projects the recorded direct p wave amplitudes into the earthquake source region a northwest southeast striking rupture of 17 km length is imaged propagat ing with an average velocity up to 3 km s this value is significantly higher than our estimate of 2 2 km s from s wave spectra our case study demonstrates that the use of array techniques and a dense accelerometer network can provide quick and robust estimates of source parameters of moderate sized earthquakes located outside the network

preservation of elemental and isotopic source identification of sedimentary organic matter the amount and type of organic matter in the sediments of lakes and oceans contribute to their paleoenvironmental and paleoclimatological records only a small fraction of the initial aquatic organic matter survives destruction and alteration during sinking and sedimentation selective degradation modifies the character of the surviving small fraction of organic matter which becomes incorporated in bottom sediments organic matter alterations can continue to sub bottom depths of hundreds of meters corresponding to millions of years source and paleoenvironmental information nonetheless remains preserved in the molecular elemental and isotopic compositions of organic matter c n and 13c values of total organic matter in particular appear to retain paleoenvironmental information for multi myr time periods

a study on the variations of recent seismicity in and around the central anatolian region of turkey abstract variations of the recent seismicity in and around the central anatolian region of turkey were evaluated based on the seismic b value standard normal deviate z value genas modelling annual probabilities and return periods of the earthquakes the catalog includes 16 702 earthquakes between 1974 and 2019 with magnitudes from 1 0 to 6 3 time distribution of b value shows that there is a tendency to decrease after the year of 2002 and b value decreased from 1 58 0 03 to 1 25 0 05 at the beginning of 2019 annual probabilities for magnitude ranges of 3 0 4 0 have the values between 3 and 30 return periods for magnitude levels of 5 0 5 5 have the values from 5 to 20 years and a value of 80 years for magnitude level of 6 0 the genas results show the significant temporal variations in the number of earthquakes smaller and larger than specific magnitude intervals by supplying the beginning periods of increases and decreases in the earthquake activity rate remarkable reductions in region time distribution of b value at the beginning of 2019 were detected in the regions covering nigde fault and its vicinity along the south west northwest and southwest directions among the mut fault zone karsanti karaisali fault zone and karatas osmaniye fault zone in and around surgu fault and along its northwest direction between surgu fault and east anatolian fault zone significant seismic quiescence areas in z value distribution include the northwest ends of the tuzgolu fault zone and study area including akpinar fault the northeast of salanda fault between salanda fault and the central anatolian fault zone the northeast parts of the central anatolian fault zone the west of malatya fault between surgu fault and the east anatolian fault zone the southeast end of the tuzgolu fault zone karsanti karaisali fault zone and its vicinity the southwest of tuzgolu thus these anomaly areas observed in the central anatolian region and its vicinity at the beginning of 2019 may be one of the most likely zones for the next strong large earthquake occurrences

monazite ages and the evolution of the menderes massif western turkey the menderes massif experienced polyphase deformation but distinguishing pan african events from alpine tectono metamorphic evolution and discriminating eocene oligocene shortening from recent extension remain controversial to address this monazite in garnet bearing rocks from the massif s gordes central and cine sections were dated in thin section in situ using the th pb ion microprobe method cambro ordovician monazite inclusions in cine and central menderes massif garnets are 450 m y older than matrix grains monazites in reaction with allanite from the kuzey detachment which bounds the northern edge of the central menderes massif are 17 5 ma and 4 5 1 0 ma the pliocene result shows that dating of monazite can record the time of extension the kuzey detachment might have exhumed rocks a lateral distance of 53 km at a rapid rate of 12 mm year assuming the present 20 ramp dip pliocene monazite crystallization at 450 c and a geothermal gradient of 25 c km assuming an angle of 60 the rate decreases to 5 mm year with the detachment surface at 21 km depth in the pliocene two gordes massif monazites show a similar allanite monazite reaction relationship and are 29 6 1 1 ma and 27 9 1 0 ma suggesting that the cenozoic extension in the gordes massif and possibly the entire menderes massif might have begun in the late oligocene

neotectonic structures in izmir gulf and surrounding regions western turkey evidences of strike slip faulting with compression in the aegean extensional regime abstract of single channel 70 km and 900 km of multi channel seismic reflection data show that izmir gulf and surrounding regions are widely deformed by n s to ne sw trending active transpressional strike slip faults reverse faults and some e w normal faults normal faults are mapped offshore karaburun foca in inner part of izmir gulf offshore alacati teke and offshore kusadasi delimiting the southern scarp of lesvos basin izmir basin northern scarp of ikaria basin and continuation of kucuk menderes graben respectively normal faults are cut by strike slip faults the major strike slip faults are the n s oriented karaburun reverse fault bordering izmir gulf on the west and uplifting the karaburun peninsula and the ne sw oriented strike slip tuzla fault extending from doganbey promontory towards seferihisar ridge onland this fault pattern can be explained by pure shear model indicating that the area is under e w compression n s extension ne sw and nw se strike slip deformation moreover tuzla fault has a regional importance it separates ne sw trending structures of the study area from e w oriented gediz and kucuk menderes grabens and probably continues towards to iznik at north constituting a transition zone between northern transpressional region and southern extensional region in the western anatolia aegean sea

late cenozoic volcanic evolution of the northeastern aegean region abstract late cenozoic volcanism occurred in an extensional tectonic regime in the northeastern aegean activity commenced in northeastern greece during the early oligocene and in northwestern turkey during the late oligocene early miocene the beginning of activity was characterized by calc alkaline intermediate acid volcanism however alkaline intermediate basic volcanism became dominant from the late miocene until the pleistocene this change in nature of volcanism is not related to a change of regional tectonic regime as previously thought instead we propose that the volcanic evolution reflects an increasing asthenospheric contribution facilitated by a thinned extended lithosphere arising from the regional extensional tectonics

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

a conjugate strike slip fault system within the extensional tectonics of western turkey summary three main shocks m 1 m 2 and m 3 17 october 2005 at 05 45 utc m w 5 4 17 october at 09 46 utc m w 5 8 and 20 october at 21 40 utc m w 5 9 and their associated after shocks within the gulf of si gacik 50 km southwest of izmir turkey were studied in detail a temporary seismic network deployed during the activity allowed the hypocentre of m 3 and subsequent aftershocks to be determined with high accuracy a relative relocation technique was used to improve the epicentres of m 1 and m 2 all three main shocks have strike slip mechanisms which agree with the linear trends of the aftershock locations two distinct zones were illuminated by the aftershock locations the zones contain clear echelon patterns with slightly different orientations from the trend of the aftershock distribution m 2 and m 3 rup tured along of the eastern rupture zone which aligns n45 e however the strike direction of m 1 is not clearly identified the alignment of the two rupture zones intersect at their southern terminus at an angle of 90 the fault zones form conjugate pair system and static triggering is considered as a probable mechanism for the sequential west to east occurrence of m 1 m 2 and m 3 this earthquake sequence provides seismological evidence for conjugate strike slip faulting co existing within a region dominated by north south extension and well developed east west trending normal faults

the izmit kocaeli turkey earthquake of 17 august 1999 previous seismicity aftershocks and seismotectonics a field experiment carried out from 17 july to 2 november 1999 with a dense seismic network surrounding the marmara sea region and including the rupture zone of the izmit kocaeli destructive earthquake of 17 august 1999 m w 7 6 harvard centroid moment tensor delouis et al 2002 permitted the collection of precise seismic data and the quantitative evaluation of the associated set of surface ruptures a previous experiment conducted in 1995 had already given reliable information about the distribution of seismicity in space focal mechanisms and the regional stress regime aftershock distribution and clustering together with the variations of slip amplitude along the fault allow the identification of at least five segments a maximum horizontal displacement of about 5 m is observed in golcuk and east of sapanca lake the rupture is extremely linear but its complexity increases toward the western end including the bifurcation the stress field associated with the aftershocks is compared with the one obtained in 1995 showing the invariance of the smallest principal axis lack of definition of the other principal axes suggests a transition from shear to extension a clear quiescence period of 18 days preceded the izmit earthquake a precursor which occurred 100 sec before had the same epicenter as the mainshock manuscript received 30 august 2000

evidence from the gediz graben for episodic two stage extension in western turkey western turkey falls within a wide belt of nne ssw directed active continental extension generally similar to the basin and range province of the usa it comprises a zone of wnw ese trending major grabens detailed study of the gediz graben reveals two contrasting infills that represent two distinct extensional stages separated by a short phase of compression the older infill consists of an 800 m thick folded and exhumed continental sedimentary sequence with intercalated calc alkaline volcanics it accumulated in a basin formed in the northern hanging wall of a detachment fault during miocene early pliocene times the younger infill rests on the older infill with angular unconformity and consists of about 170 m of undeformed terraced continental sediments and basaltic lavas it accumulated during plio quaternary times in an asymmetric graben bounded by step like normal faults this later extension was probably triggered by the commencement of sea floor spreading along the red sea in early pliocene times and has persisted to the present almost all the grabens in western turkey are best explained by this episodic two stage graben model with an intervening phase of short term compression which differs from the progressive evolution inferred for the basin and range province of the usa

3 d imaging of the upper crust beneath the denizli geothermal region by local earthquake tomography western turkey abstract the denizli basin and its surroundings are one of the regions that have high seismic activity and rich geothermal fields in western anatolia in the first half of year 2000 an increasing seismic activity was observed around the denizli basin without a large mainshock occurrence a temporary seismic network consisting of 28 stations were deployed to observe the seismic activity in the region by the scientific and technological research council of turkey marmara research center earth and marine science institute tubitak mam emsi in this study one and three dimensional vp and vp vs structure of the denizli basin have been determined by using the travel times of the 635 recorded earthquake data firstly one dimensional inversion schema was performed to stabilize initial velocity model and to have more reliable hypocentral locations then an iterative and simultaneous three dimensional inversion procedure was carried out to obtain 3 d high resolution seismic velocity models furthermore to assess the solution quality of our inversion we conducted a series of resolution tests we concluded high resolution 3 d vp and vp vs seismic velocity models for the upper 20 km of the crust beneath the denizli basin and surroundings and interpreted the results in the context of known geologic and tectonic units the resulting 3 d vp models define the geometry of the basin sediment thickness and intrusive magmatic bodies as well as regions of anomalous velocity the vp vs models help to constrain the location and geometry of the faults zones of weakness and gas or fluid saturated formations with high pore pressure zones all tomographic results show that there is a strong correlation between local seismicity and the high vp and vp vs anomalies consequently this relationship indicates that the reason of the high seismicity in the denizli basin depends on activity of hydrothermal system as well as tectonic regime

strike slip motions in the gulf of sigacik western turkey properties of the 17 october 2005 earthquake seismic sequence abstract the october 2005 series of earthquakes that occurred in the gulf of sigacik western turkey reveal the operation of pure strike slip faults as evidenced from the 49 focal mechanisms we determined in a region dominated by n s extension and bounded by well documented graben structures the sequence is characterized by the occurrence of three moderate size events 17 october 2005 05 45 utc mw 5 4 17 october 2005 09 46 utc mw 5 8 and 20 october 2005 21 40 utc mw 5 8 with an eastward propagation and close spatial separation

timing of cenozoic extensional tectonics in west turkey the timing of the transition from compressional to extensional tectonics in the late cenozoic evolution of west turkey has been constrained by k ar geochronology from acidic volcanic rocks and tourmaline leucogranite dykes in the central and east margin respectively of the gordes basin dacites and rhyolites in the centre of the gordes neogene sedimentary basin cut both the basement ophiolites of the izmir ankara suture zone and the neogene sediments on the basin s eastern margin the leucogranites cut metamorphic basement along a major ne sw trending normal fault that controls the regional structure of the basin pebbles of these leucogranites occur in adjacent neogene turfites and conglomerates k ar dates on biotites from the central volcanic rocks vary from 18 4 0 8 ma to 16 3 0 5 ma early miocene whilst muscovite from a leucogranite on the eastern margin of the basin provides ages of 24 2 0 8 ma and 21 1 1 1 ma latest oligocene to early miocene geochronological data and field relationships demonstrate that the earlier compressional regime had been replaced by extensional tectonics by latest oligocene early miocene

an improved method for determining the regional stress tensor using earthquake focal mechanism data application to the san fernando earthquake sequence the orientations of fault planes and slip directions indicated by a population of earthquake focal mechanisms can be used to determine best fit regional principal stress directions and r 2 1 3 1 a measure of relative stress magnitudes under the assumption of uniform stress in the source region this analysis allows for the possibility that failure occurs on preexisting zones of weakness of any orientation in the inversion we perform a grid search of stress models to find the one which requires the smallest total rotation of all the fault planes that is needed to match the observed and predicted slip directions the method allows for errors in orientations of both the fault planes and slip directions we have an objective means for identifying the more likely of the two possible fault planes from each focal mechanism relative to a given stress model thus we do not face the problem of ambiguity of nodal planes which plagues other analyses of this kind by using a grid search of stress models rather than a linearization scheme we are able to perform a realistic error analysis and thus establish confidence limits for the preferred regional stresses the method can be used to investigate possible stress inhomogeneities during earthquake sequences by analyzing subsets of the data population the technique has been applied to 76 events from the san fernando earthquake sequence for which we have found best fit stresses plunge and azimuth 1 7 187 2 27 281 3 62 84 and r 0 65 the average misfit between this stress model and all the data is about 8 and all but eight of the aftershocks have misfits of less than 20 these values are considerably less than the uncertainty of the focal mechanism determinations therefore significant stress inhomogeneities are not required by the data our analysis does not support the suggestion of a change in stresses during the aftershock sequence as proposed by others on the basis of an apparent change in focal mechanisms

the use of uniaxial recordings in moment tensor inversions for induced seismic sources abstract this study shows that the use of uniaxial recordings maintains the linear dependence of the low frequency displacements with first polarities included on the moment tensor components and thus can be easily incorporated in the evaluation of failure mechanism using a moment tensor approach synthetic data analysis demonstrates that the errors in the orientation of the principal strain axes of the mechanism solution can be reliably evaluated using a linear error propagation approximation for up to 30 variance in the amplitude data case studies at the kidd mine indicate that the general characteristics of the mechanism solution are well retrieved regardless of the type of data used as relatively small disorientation angles of 15 20 are found between the solutions derived from rotated triaxial data and those from unrotated triaxial data used as uniaxial data and of 25 30 between the solutions based on rotated triaxial data and those on independent uniaxial data

block rotation in western turkey 1 observational evidence western turkey is a region of rapid continental extension where extension rate increasing westward causes counterclockwise vertical vorticity and hence counterclockwise rotation around vertical axes on a regional scale field observations and seismicity of the past century are used to deduce positions and slip senses of major active oblique normal faults in this region which take up extension in the upper crustal brittle layer and allow fault bounded blocks to rotate around vertical axes the principal active normal faults in western turkey strike roughly east west near the aegean coast turning gradually toward westnorthwest eastsoutheast strike across 200 km distance inland to the east slip vector azimuths indicate typical extension direction on these faults is s18 8w they truncate a second set of faults with smaller displacement and roughly orthogonal strike and slip vector azimuth as well as subdividing the brittle layer into blocks that show little internal deformation some major oblique normal faults subdivide it into domains that show different neogene rotation around vertical axes some domains contain sets of major active oblique normal faults that bound blocks that are elongated angular and shaped like tilted dominoes these faults take up extension and can also take up rotation around vertical axes provided they and the blocks between them rotate around vertical axes at the same rate where adequate paleomagnetic observations are available they indicate these domains have rotated counterclockwise as expected by up to 40 roughly equal to the change in strike of the principal set of active faults between the aegean coast and the eastern edge of the actively extending zone however evidence is scarce for the right lateral strike slip expected in some kinematic models on a set of oblique normal faults that takes up extension and counterclockwise rotation instead each fault appears to have the component of strike slip necessary to enable it given its local strike to slip in ue direction in which the region is extending two domains that have rotated clockwise are approximately circular in plan view with diameter 90 km and are bounded by faults with variable orientation each comprises a single block with no internal major active faults

calculating horizontal stress orientations with full or partial knowledge of the tectonic stress tensor calculating horizontal stress orientations with full or partial knowledge of the tectonic stress tensor

calibration of an ml scale in northwestern turkey from 1999 izmit aftershocks a local magnitude scale is derived for northwestern turkey using data collected by a temporary network installed by the german task force for earthquakes after the 1999 izmit earthquake m w 7 4 and the permanent sapanca bolu network we computed wood anderson seismograms for over 5353 arrivals at 27 three component stations from 530 earthquakes the hypocentral distances considered range from 5 to 140 km with the best represented range being from 5 to 70 km we inverted the measured amplitudes following both the nonparametric richter s 1958 and parametric bakun and joyner 1984 approaches these methods yield consistent magnitude values and station corrections however the calculated nonparametric distance correction log a implies that ground motion attenuation is higher than what is accounted for by the equation calibrated in central california in the range 5 62 km the best fit is provided by log a log r 17 0 00960 r 17 2 this equation is obtained constraining the geometrical spreading parameter n to 1 the calculated value of k 0 00960 confirms that in this range of distance seismic waves could propagate through a low q volume station corrections which allow for a significant reduction of m l residuals range between 0 5 magnitude units suggesting a strong influence of local site effects on the amplitude of ground motion in accord with the obtained attenuation and station corrections the magnitudes of the considered events range from 0 4 to 4 8

moment tensor inversion of microseisms from the b sand propped hydrofracture m site colorado abstract we apply a moment tensor inversion algorithm to microseismic events generated by hydrofracturing our dataset consists of microseismic events associated with a hydraulic fracturing experiment conducted at the gri doe m site near rifle colorado the event recordings were from a vertical string of 3 component accelerometer pods that are cemented in a borehole the accelerograms clearly show p and s waves which can be rotated into the sh and sv components to invert the p and s amplitudes for moment tensors we use just the first two peaks after the first arrival using this amplitude information and the average pulse width we formed a symmetric stylized pulse for integration and we inverted for the moment tensor resolution tests revealed that with the source microseism to receiver geometry we have at the m site where all receivers are in one borehole and at the same azimuth from the source we can extract the five deviatoric components of the moment tensor using combinations of p sh and sv amplitudes for example a minimum data set of 3 p wave 2 sv wave and 1 sh wave amplitudes to obtain the sixth component which is the isotropic component requires amplitude information from receivers at another azimuth we studied seven high quality events in detail and tested their results against two alternative source geometries these microseismic events tend to have a major double couple nodal plane aligned parallel to the main hydrofracture plane rather than have their tension t axes aligned parallel to the regional minimum principal compressive stress direction the events have seismic moments m0 on the order of 10 5 nm and moment magnitudes mw of about 2 5

gold in the southwest of the iberian peninsula during the 3rd millennium bc abstract in the southwest of the iberian peninsula one of the main gold mining regions in western europe the presence of the first gold products are noted in the archaeological records of 3rd millennium bc megalithic tombs at some distance from the mining districts the lack of systematic programmes to analyse such archaeological gold finds has led them to being identified as ornamental finds of undetermined chronology linked to a simple manufacturing technology of hammering gold nuggets of an uncertain origin or from the eastern mediterranean as well as items with a purely symbolic or prestige value in the funerary practices of simple group oriented or collaborative chiefdoms but however the first documentation radiocarbon dating and systematic analysis of these products in settlement contexts has altered this interpretation the presence of gold manufactures during the third quarter of the 3rd millennium bc c 2500 2350 cal bc in the contexts of a settlement specialised in copper production such as cabezo jure in the south western mining region huelva spain and in the contexts of a huge central site such as valencina de la concepcion in the agrarian region of the lower guadalquivir basin seville spain points to the widespread social use of gold in the period of maximum expression of the inter settlement hierarchisation in the southwest of the iberian peninsula its link with the social spaces of inequality expression and their relationship with a complex production system geochemical characterization by la icp ms lead isotopes analysis by mc icp ms and metallographic study suggest two differentiated and independent supplies of raw material systems fluvial placers vs mines and local vs regional scale with at least four source areas the regional circulation of raw material or products and a manufacturing by a metallurgical technology linked to the copper production

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 quaternary tectonic and sedimentary history of outer izmir and candarli bays western turkey abstract air gun and 3 5 khz seismic profiles from the eastern aegean sea off turkey show that the continental shelf of outer izmir and candarli bays is formed by several superimposed deltaic sequences during times of lowered sea level associated with late quaternary glaciations deltas prograded seaward more than 60 km from their present positions foreset progradation ceased with the rise of sea level in interglacial and post glacial times and deltas were reestablished far inland in drowned river valleys these major transgressions resulted in unconformities within the superimposed prograded delta sequences the most recent three unconformities are correlated with the beginning of oxygen isotope stages 5 3 and 1 and provide chronostratigraphic markers for a detailed analysis of sedimentation patterns in the late quaternary the coastal shelf and basins are subsiding at an average rate of about 1 m per 1000 years this tectonic subsidence manifests itself as widespread normal block faulting which can be related to the pre miocene structural framework of the region

estimation of causative fault parameters of the rudbar earthquake of june 20 1990 from near field sh wave data abstract we analyze the strong motion accelerograms recorded for the large m s 7 7 m w 7 3 m b 6 4 rudbar earthquake of june 20 1990 the earthquake had a complex source process we have identified the imprints of rupture of three localized asperities on the major causative fault on the accelerograms these asperities are interpreted to correspond to i the main shock that initiated the rupture process and was located in the domino block between the kabateh and zard goli faults ii a foreshock that occurred about 10 s earlier in the kabateh fault and iii a later shock on the western end of the baklor fault which terminated the bilateral rupture process at the western end we estimate the strike dip and slip of these causative sub event rupture planes using the sh spectral amplitudes based on a point source representation of sub events and a non linear least square formulation for inversion of the amplitude data the results of our inversion of the near field data are comparable to other studies based on teleseismic data

the aegean sea we summarize briefly the main features of a kinematic model of evolution of the aegean area since 13 ma the formation of the aegean sea by extensional tectonics is related to the subduction of the mediterranean floor below the hellenic arc we then make a quantitative estimate of vertical movements in the aegean area on the basis of geological data and demonstrate that the outer arc was built since the beginning of this episode of subduction by vertical uplift the easiest way to explain the uplift is by underplating finally we discuss briefly the dynamics of the subduction marginal sea formation processes in this continental collision framework

paleoclimatic implications of holocene lake level fluctuations owasco lake new york radiocarbon controlled stratigraphic data from owasco lake valley new york document two cycles of relative lake level change during the holocene in response to regional variations in effective precipitation lake highstands occurred at 10 5 and 6 9 ka with an intervening lowstand at 9 ka the 10 5 ka highstand occurred during the well known killarney younger dryas cold interval 11 2 10 0 ka in response to decreased evaporation and increased precipitation the driest interval of the early middle holocene occurred 9 ka at the time of maximum summer solar insolation a second highstand occurred during the hypsithermal 8 5 5 5 ka in response to increased precipitation at a time when the interior of north america underwent maximum aridity this out of phase relationship between northeastern north america and the midcontinent during the hypsithermal may have been a consequence of a northward shift of the jet stream and a change of precipitation patterns in response to increased global warmth if the hypsithermal can be used as an analog for potential global warming the northeastern united states may experience future increases in regional precipitation

source parameters and scaling relations of local earthquakes from a strong motion network in izmir western turkey this study reports the estimation of source parameters in and around izmir western anatolia turkey using data recorded by 18 strong motion stations belonging to the local accelerometer array izmirnet the displacement spectra of sh waves are calculated for 55 earthquakes with a moment magnitude range mw of 3 4 to 5 7 recorded by at least ten stations the corner frequency f0 spectral level and fmax are acquired from the displacement spectra in order to analyse the source characteristics of the events using brune s source model seismic moment m0 values are computed between 12 74 and 17 93 nm spectral level 0 values are detected between 3 17 and 6 44 nm s source radius r values are calculated from 0 45 to 2 28 km and seismic energy values are estimated between 2 07 1013 and 6 45 1020 erg computed stress drop values vary from 0 72 to 346 9 bar and this result is significantly lower than the values of 0 017 and 647 6 bar reported for the marmara region northwestern anatolia turkey and slightly lower than the source sizes of the events of between 0 0862 and 5 1042 km however similar results were found for seismic moments koseoglu et al in j seismol 18 651 669 https doi org 10 1007 s10950 014 9435 2 2014 from the results of the present study it is concluded that scattering in seismic moment stress drop and hypocentral distance during large earthquakes is observed by an increase in f0 and fmax which is related to the complex tectonism of the study area

multistage exhumation of the menderes massif western anatolia turkey structural analyses along selected transects across the menderes massif and incorporation of existing data have resulted in a synthetic cross section across southwestern turkey the tectonic interpretation has been combined with 40ar 39ar laser probe experiments on two syn kinematic white mica populations which respectively predate and overprint documented early miocene deformational fabrics our results indicate that the regional extension had initiated by eocene oligocene times a 36 2 ma 40ar 39ar age derived from white mica which formed during a regionally observed northward directed tectonic transport suggests that the extension was contemporaneous with the tectonic emplacement of mid crustal continental basement alternatively the age may relate to the regional cooling of the basement sequence and thus postdates the tectonic emplacement in the latter scenario the analysis fails to solve the present ambiguity on the pan african or alpine affinity of the northward directed transport further exhumation of basement rocks is characterized by a dominant displacement along the north dipping gediz detachment at the northern margin of the massif which developed under ductile conditions in the early miocene by partial exploitation of older zones of weakness which originated from an earlier phase of basement emplacement youngest semi ductile activity along the gediz detachment has been recorded as having a 7 1 ma 40ar 39ar age derived from syn kinematic white mica in the top of the detachment following the initiation of the ductile gediz detachment an antithetic semibrittle and south dipping buyuk menderes detachment had developed in the center of the massif which together with the gediz detachment accommodated further doming of the central part of the menderes massif and controlled the architecture of the surrounding supradetachment basins