structural characterization of natural loess and remolded loess under triaxial tests this paper characterizes the microstructural evolution of saturated natural loess from a site in jingyang china during triaxial test along two stress paths for comparison the same soil in remolded state is also characterized mercury intrusion porosimetry mip scanning electron microscopy sem and environmental scanning electron microscopy esem were used for the microstructure investigation results show that the microstructure of natural loess is similar to that of remolded loess before the consolidated undrained cu triaxial tests including conventional triaxial compression ctc test and reduced triaxial compression rtc test on the contrary their microstructures are different after the tests deeper examination shows that loading led to a significant change of inter aggregate pores without modifying the intra aggregate pores in addition the volume of inter aggregate pores after the rtc test is greater than that after the ctc test under the same consolidation stress the microstructure features of natural and remolded loess after the tests are further used to analyze the macro mechanical behavior for better understanding the relationship between them the results show that it is the cementation bonds of which breakage is influenced by stress path and confining pressure that play important roles in the strength and deformation behavior

quantifying climatic change through the last glacial interglacial transition based on lake isotope palaeohydrology from central turkey questions remain as to the nature of climatic change through the last glacial interglacial transition in the eastern mediterranean region particularly the relative contribution of evaporation and precipitation to regional water balance here changes in oxygen isotope values through this time period from eski acigol a crater lake in central turkey are investigated using hydrological and isotope mass balance models these allow changes in evaporation and precipitation to be quantified and their relative importance evaluated we show that it is the volumetric flux rate of water passing through the lake system and not the precipitation to evaporation ratio per se which controlled the stable isotope record in eski acigol early holocene precipitation is shown to be much greater than that during both the latter part of the last glaciation and the present day we test these calculated values against other records in the same region firstly with other lake records in anatolia the konya basin and lake van and secondly with isotope inferred palaeo precipitation data from soreq cave in israel this reveals a contrast between pre and post lgm precipitation values in turkey wetter and drier respectively and also suggests that during the last glacial interglacial transition there was a more marked precipitation gradient than at present between northern interior and southern coastal parts of the eastern mediterranean region

characterization of the mechanisms underlying loess collapsibility for land creation project in shaanxi province china a study from a micro perspective abstract using the major land creation project to bulldoze mountains to build cities implemented in the city of yan an as an example the collapse potential microscopic observations quantitative analyses and qualitative characterization of the microstructures of loess sampled from yan an were investigated to probe the fundamental mechanisms of loess collapsibility at the micro scale the results show that loess in yan an exhibits a severe degree of collapse potential as indicated by its maximum collapse index of 8 10 at a vertical stress value of 600 kpa from a compositional and microstructural perspective a large proportion of loosely arranged skeletal particles are widely separated by variants of clay fabric forming a metastable structure with a high pore area ratio of 32 67 and demonstrating an unstable contact between particles in natural loess these intrinsic microstructural features with a high degree of collapse potential act synergistically to augment collapse when loess is saturated under a certain load the initially high stiffness provided by the delicate clay fabric can be destroyed by its softening dispersion or disruption unsupported skeletal particles are then rearranged significantly into a more stable structure at the same time pores larger than 60 m create favorable spatial conditions for wetting deformation thereby spurring an abrupt reduction in pore size and area particles reorganize into a closely packed structure more interlocking pores of

slip along the sultanhani fault in central anatolia from deformed pleistocene shorelines of palaeo lake konya and implications for seismic hazards in low strain regions

millennial to interannual climate variability in the mediterranean during the last glacial maximum climate change during the late pleistocene is dominated by periodicities on millennial time scales as documented by ice cores and sedimentary marine and terrestrial records of global distribution interannual to decadal variations have also been demonstrated in dust concentrations in greenland ice cores but there is lack of comparable detail in sedimentary records an 8 5 m long multiproxy record from lake albano central italy spanning the time interval between 15 0 and 28 0 cal kyr bp reveals a high temporal resolution window into climate change during the last glacial maximum lgm distinct warm cold cycles of millennial to centennial duration indicate a major response of the lake to climate induced environmental changes flickering interannual to interdecadal variations within these cycles are interpreted to reflect oscillations of the north atlantic nao implying shifts in temperature wind strength source of moisture and atmospheric circulation pattern

new constraints on the active tectonic deformation of the aegean 1 site velocities from six separate global positioning system gps networks comprising 374 stations have been referred to a single common eurasia fixed reference frame to map the velocity distribution over the entire aegean we use the gps velocity field to identify deforming regions rigid elements and potential microplate boundaries and build upon previous work by others to initially specify rigid elements in central greece the south aegean anatolia and the sea of marmara we apply an iterative approach tentatively defining microplate boundaries determining best fit rigid rotations examining misfit patterns and revising the boundaries to achieve a better match between model and data short term seismic cycle effects are minor contaminants of the data that we remove when necessary to isolate the long term kinematics we find that present day aegean deformation is due to the relative motions of four microplates and straining in several isolated zones internal to them the rms misfit of model to data is about 2 sigma very good when compared to the typical match between coseismic fault models and gps data the simplicity of the microplate description of the deformation and its good fit to the gps data are surprising and were not anticipated by previous work which had suggested either many rigid elements or broad deforming zones that comprise much of the aegean region the isolated deforming zones are also unexpected and cannot be explained by the kinematics of the microplate motions strain rates within internally deforming zones are extensional and range from 30 to 50 nanostrain year nstrain year 10 9 year 1 to 2 orders of magnitude lower than rates observed across the major microplate boundaries lower strain rates may exist elsewhere within the microplates but are only resolved in anatolia where extension of 13 4 nstrain year is required by the data our results suggest that despite the detailed complexity of active continental deformation revealed by seismicity active faulting fault geomorphology and earthquake fault plane solutions continental tectonics at least in the aegean is to first order very similar to global plate tectonics and obeys the same simple kinematic rules although the widespread distribution of aegean seismicity and active faulting might suggest a rather spatially homogeneous seismic hazard the focusing of deformation near microplate boundaries implies the highest hazard is comparably localized

late neogene and active orogenic uplift in the central pontides associated with the north anatolian fault implications for the northern margin of the central anatolian plateau turkey 1 surface uplift at the northern margin of the central anatolian plateau cap is integrally tied to the evolution of the central pontides cp between the north anatolian fault naf and the black sea our regional morphometric and plate kinematic analyses reveal topographic anomalies steep channel gradients and local high relief areas as indicators of ongoing differential surface uplift which is higher in the western cp compared to the eastern cp and fault normal components of geodetic slip vectors and the character of tectonic activity of the naf suggest that stress is accumulated in its broad restraining bend seismic reflection and structural field data show evidence for a deep structural detachment horizon responsible for the formation of an actively northward growing orogenic wedge with a positive flower structure geometry across the cp and the naf taken together the tectonic plate kinematic and geomorphic observations imply that the naf is the main driving mechanism for wedge tectonics and uplift in the cp in addition the naf zone defines the boundary between the extensional cap and the contractional cp the syntectonic deposits within inverted intermontane basins and deeply incised gorges suggest that the formation of relief changes in sedimentary dynamics and 1 km fluvial incision resulted from accelerated uplift starting in the early pliocene the central pontides thus provide an example of an accretionary wedge with surface breaking faults that play a critical role in mountain building processes sedimentary basin development and ensuing lateral growth of a continental plateau since the end of the miocene

viscosity structure of the crust and upper mantle in western nevada from isostatic rebound patterns of the late pleistocene lake lahontan high shoreline received 13 july 2005 revised 26 october 2006 accepted 31 january 2007 published 8 june 2007 1 large lakes can both produce and record significant crustal deformation we present an analysis of the isostatic rebound pattern recorded in the shorelines of paleolake lahontan in western nevada using a layered maxwell viscoelastic model the inferred viscosity structure depends on loading history we use three variants of a well documented lake surface elevation model as input and recover corresponding estimates of viscosity and density structure a simple two layer model with an elastic plate over an inviscid half space fits the observed elevation pattern quite well with a residual variance of 32 of the data variance using multilayered finite viscosity models the residual variance is reduced to 20 of the data variance which is very near to the noise level in the higher resolution models the viscosity is below 10 18 pa s over the depth range from 80 to 160 km the minimum viscosity is very similar to the value that has been seen in the eastern great basin from similar analyses of lake bonneville shorelines but the lowviscosity zone is thinner beneath bonneville making small adjustments to a seismically derived density structure allows an improved fit to the shoreline observations additionally we find that small variations in proposed loading models can result in presumably spurious density inversions and suggest that this modeling approach provides a test for loading histories

60 k y record of extension across the western boundary of the basin and range province estimate of slip rates from offset shoreline terraces and a catastrophic slide beneath lake tahoe deformation across three major fault strands within the lake tahoe basin has been mapped by using a novel combination of high resolution seismic chirp airborne laser and acoustic multibeam derived bathymetry and deep and shallow water sediment cores submerged erosional terraces of late pleistocene age 19 2 6 1 8 ka record vertical de formation across fault strands that ranges between 10 and 15 m offset of 10 m is observed across the southern part of the west tahoe fault avalanche deposits from the catastrophic mckinney bay slide ca 60 ka are offset across the stateline fault by at least 21 25 m the submerged shoreline terraces and debris avalanche provide marker beds with which to constrain the extensional history of the region for the past 60 k y this history is then used to assess the future seismic hazard of the region data on deformation across these two important marker beds combined with chronological control from 14 c and optically stimulated luminescence measurements yield an estimate of extension across the lake tahoe basin that is 0 4 0 5 mm yr on the basis of these measurements there exists the potential for a large seiche wave generating m7 earthquake every 3 k y late pleisto cene and holocene vertical deformation rates within the tahoe basin are characteristic of basin and range faulting and place the tahoe basin within the western limits of the extensional basin and range province

temporal and spatial variability of tidal fluvial dynamics in the st lawrence fluvial estuary an application of nonstationary tidal harmonic analysis predicting tides in upstream reaches of rivers is a challenge because tides are highly nonlinear and nonstationary and accurate short time predictions of river flow are hard to obtain in the st lawrence fluvial estuary tide forecasts are produced using a one dimensional model one d forced downstream with harmonic constituents and upstream with daily discharges using 30 day flow forecasts from lake ontario and the ottawa river although this operational forecast system serves its purpose of predicting water levels information about nonstationary tidal fluvial processes that can be gained from it is limited particularly the temporal changes in mean water level and tidal properties i e constituent amplitudes and phases which are function of river flow and ocean tidal range in this paper a harmonic model adapted to nonstationary tides ns tide was applied to the st lawrence fluvial estuary where the time varying external forcing is directly built into the tidal basis functions model coefficients from 13 analysis stations were spatially interpolated to allow tide predictions at arbitrary locations as well as to provide insights into the spatiotemporal evolution of tides model hindcasts showed substantial improvements compared to classical harmonic analyses at upstream stations the model was further validated by comparison with one d predictions at a total of 32 stations the slightly lower accuracy obtained with ns tide is compensated by model simplicity efficiency and capacity to represent stage and tidal variations in a very compact way and thus represents a new means for understanding tidal rivers

faulting associated with historical and recent earthquakes in the eastern mediterranean region summary this paper summarizes evidence for surface faulting in historical and recent earthquakes in the eastern mediterranean region and in the middle east such information is particularly important for studies of active tectonics and for palaeoseismology we have found 78 cases of faulting pre 1900 and 72 post 1900 some of which show that faults that have apparently been inactive this century had already ruptured before 1900 for some cases faulting could not have been predicted from 20th century activity and in others it could have been expected but has not been observed during the instrumental period the data are suycient to allow the derivation of relationships between magnitude and rupture length

strain and rotation rate from gps in tibet anatolia and the altiplano 1 deformation measured by regional gps networks in continental plateaus reflects the geologic and tectonic variability of the plateaus for two collisional plateaus tibet and anatolia and one noncollisional the altiplano we analyze the regional strain and rotation rate by inverting gps velocities to calculate the full two dimensional velocity gradient tensor to test the method we use gridded velocities determined from an elastic block model for the eastern mediterranean middle east region and show that to a first order the deformation calculated directly from the gps vectors provides an accurate description of regional deformation patterns principal shortening and extension rate axes vertical axis rotation and two dimensional 2 d volume strain dilatation are very consistent with long term geological features over large areas indicating that the gps velocity fields reflect processes responsible for the recent geologic evolution of the plateaus differences between geological and gps descriptions of deformation can be attributed either to gps networks that are too sparse to capture local interseismic deformation or to permanent deformation that accrues during strong earthquakes the altiplano has higher internal shortening magnitudes than the other two plateaus and negative 2 d dilatation everywhere vertical axis rotation changes sign across the topographic symmetry axis and is due to distributed deformation throughout the plateau in contrast the collisional plateaus have large regions of quasi rigid body rotation bounded by strike slip faults with the opposite rotation sense from the rotating blocks tibet and anatolia are the mirror images of each other both have regions of positive dilatation on the outboard sides of the rotating blocks positive dilatation in the aegean correlates with a region of crustal thinning whereas that in eastern tibet and yunnan province in china is associated with an area of vertical uplift rollback of the hellenic trench clearly facilitates the rotation of anatolia rollback of the sumatra burma trench probably also enables rotation about the eastern syntaxis of tibet

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

non darcian flow in loess at low hydraulic gradient abstract determining the mechanism of water flow in loess involves many problems that are vital to science and engineering water flow through loess has usually been assumed to follow darcy s law but this has not been properly validated the main objective of this study is to validate the applicability of darcy s law for loess for this purpose we conducted constant head permeability experiments and mercury injection porosimetry mip on loess specimens of different dry densities the results indicate that darcy s law is not suitable for describing water seepage in loess at low hydraulic gradient since there is a threshold hydraulic gradient i0 below which no flow is observed and a critical hydraulic gradient icr below which the relationship between the hydraulic gradient i and seepage velocity v is non linear the mip results show that variation in hydraulic conductivity is closely related to the pore size distribution psd in loess specimens i0 is positively correlated with the content of pores with diameters in the range of 0 01 1 m and negatively correlated with the content of pores with diameters larger than 3 m the existence of bound water on loess is the main reason that its permeability deviates from darcy s law the mechanism of water movement in loess can be fully understood by considering the effect of bound water

short and long term deformation patterns in the aegean anatolian systems insights from space geodetic data gps geodetic measurements gps in the eastern mediterranean suggest higher rates of motion of about 10 mm yr in the aegean western anatolian zone with respect to those in the central eastern anatolia in this work we explore the plausibility of the hypothesis that the observed kinematics may be significantly influenced by post seismic relaxation processes induced by the seismic activation of the north anatolian fault since 1939 the major implications of this hypothesis are tentatively quantified by a simplified model constituted by an elastic lithosphere 100 km thick coupled with a viscous asthenosphere 250 km thick with a viscosity of 10 19 pas the predicted perturbation of the displacement and stress fields is consistent with geodetic velocities and could also account for the major features of seismic activity in the period considered

a fluidized landslide occurred in the loess plateau a study on loess landslide in south jingyang tableland abstract the south jingyang tableland is located on the southern loess plateau of china ever since the introduction of the water division project in the 1970s more than 40 loess landslides have occurred in this tableland terrace slope topography here on the morning of march 8 2016 a loess landslide induced by irrigation occurred in jiangliu village on the south jingyang tableland and around 20 000 m 3 of loess rapidly slid along a 65 m high slope for 260 m the moisture content of the slip mass displayed a dramatic change along the slip direction the water saturation degree in the landslide depression was relatively high and the leading edge was in a flow state there were some local natural sub areas but the overall area showed a characteristic fluidized a field investigation indicated that while macropores developed in the loess and deep joints provided a preferential passage for the infiltration of irrigation water which became a major water source for the slip mass the softening of the toe part of the slope caused by irrigation became the major factor resulting in the instability of the slip mass undrained triaxial shear tests on loess in natural water content and fully saturated state show that the enhanced saturation degree not only lowered the soil mass strength but also increased pore water pressure resulting in the zoning status of the jiangliu landslide the angle of reach formed during this landslide was approximately 14 which demonstrated motion characteristics of long runout further considering the standing water at the slope foot and unique properties of slip soils after the landslide occurred it is speculated that the motion mechanism of this high speed and long runout landslide was associated with loess liquefaction that led to sharp decrease in shear strength of the displaced landslide materials during the shear process

environmental and climatic changes during the last 20 000 years at lake tuz central turkey abstract our study demonstrates the importance of detailed lithostratigraphic and biostratigraphic analyses of deposits of lake side terraces and alluvial fans in attempts to identify fluctuations of climate characteristics such as precipitation and evaporation rates and of local conditions for water balance changes in the central part of turkey during the last 20 000 years lake tuz basin central part of the anatolian plateau turkey had two high lake level stages dated as about 20 000 17 000 years ago and about 13 000 years ago at the high lake stages water level rose more than 15 m higher than the present lake level and the lake area spread widely to near the southern edge of the basin as inferred by lithologic and chronological investigation of drilling cores in the holocene lake level fell and the southeast part of the basin became extensive lake terraces alluvial fans have formed along the edge of the upland area on the terraces in the holocene stratigraphy and dating of the fan deposits show the fluctuations in the depositional rates of the fans major formative stages of the fans are dated about 7000 5500 and 2500 2000 years bp and several times of minor stages probably 4300 and 3000 years bp occurred between the two major stages our archaeological research shows that there are strong relationships between the distributions of archaeological sites of this area and the above geo environmental histories

on the recovery of effective elastic thickness using spectral methods examples from synthetic data and from the fennoscandian shield there is considerable controversy regarding the long term strength of continents te while some authors obtain both low and high te estimates from the bouguer coherence and suggest that both crust and mantle contribute to lithospheric strength others obtain estimates of only 25 km using the free air admittance and suggest that the mantle is weak at the root of this controversy is how accurately te can be recovered from coherence and admittance we investigate this question by using synthetic topography and gravity anomaly data for which te is known we show that the discrepancies stem from comparison of theoretical curves to multitaper power spectral estimates of free air admittance we reformulate the admittance method and show that it can recover synthetic te estimates similar to those recovered using coherence in light of these results we estimate te in fennoscandia and obtain similar results using both techniques te is 20 40 km in the caledonides 40 60 km in the swedish svecofennides 40 60 km in the kola peninsula and 70 100 km in southern karelia and svecofennian central finland independent rheological modeling using a xenolith controlled geotherm predicts similar high te in central finland because te exceeds crustal thickness in this area the mantle must contribute significantly to the total strength te in fennoscandia increases with tectonic age seismic lithosphere thickness and decreasing heat flow and low te correlates with frequent seismicity however in proterozoic and archean lithosphere the relationship of te to age is ambiguous suggesting that compositional variations may influence the strength of continents copyright 2004 by the american geophysical union

surface expression of eastern mediterranean slab dynamics neogene topographic and structural evolution of the southwest margin of the central anatolian plateau turkey 1 the southwest margin of the central anatolian plateau has experienced multiple phases of topographic growth including the formation of localized highs prior to the late miocene that were later affected by wholesale uplift of the plateau margin our new biostratigraphic data limit the age of uplifted marine sediments at the southwest plateau margin at 1 5 km elevation to 7 17 ma and regional lithostratigraphic correlations imply that the age is 6 7 ma single grain ca tims u pb zircon analyses from a reworked ash within the marine sediments yield dates as young as 10 6 ma indicating a maximum age that is consistent with the biostratigraphy our structural measurements within the uplifted region and fault inversion modeling agree with previous findings in surrounding regions with early contraction followed by strike slip and extensional deformation during uplift focal mechanisms from shallow earthquakes show that the extensional phase has continued to the present broad similarities in the change in the tectonic stress regime after 8 ma and the onset of surface uplift after 7 ma imply that deep seated process es caused post 7 ma uplift the geometry of lithospheric slabs beneath the plateau margin pliocene to recent alkaline volcanism and the uplift pattern with accompanying normal faulting point toward slab tearing and localized heating at the base of the lithosphere as a probable mechanism for post 7 ma uplift of the southwest margin considering previous work in the region there appears to be an important link between slab dynamics and surface uplift throughout the anatolian plateau s southern margin

a review of shear and tensile strengths of the malan loess in china abstract loess deposits cover about 640 000 km 2 of china equivalent to about 6 7 of the total area of the country the loess plateau alone covers approximately 317 000 km 2 making it the largest bulk accumulation of loess on the earth land instability hazards in the loess plateau are frequent and varied among which the cracking sliding beng hua in chinese failure is a typical mode cracking sliding failures commonly occur in the malan loess at volumes of the order of 100 m 3 and cause more than 100 deaths per year as the tension in the upper part of the failure plane and shearing sliding along the lower part mobilize cracking sliding failures this failure mode demands an investigation into the tensile and shear strengths this paper presents a review of these properties based on a large collection of literature both tensile and shear strengths of the malan loess decrease with water content and increase with dry density resulting in close multi regression correlations large differences between undisturbed and disturbed tensile strengths of the loess indicate the significance of its structure shear strength of the loess is direction dependent indicating strong anisotropy of the loess structure test method sample size and loading rate all influence the measured tensile strength

influence of structure on shear characteristics of the unsaturated loess in lanzhou china abstract loess is typically a kind of soil with metastable structure which makes loess sensitive to collapse and sliding upon wetting such structure has thus profound influence on loess s mechanical behavior however there have been arguments about how the metastable structure influences on loess s mechanical behavior and what the mechanism behind is in this study the influence of structure on shear characteristics of the unsaturated loess in lanzhou city of china was investigated with comparison of variation of shear strength and its parameters between six pairs of the undisturbed and remolded samples it is found that the peak shear strength and strength parameters of the loess significantly reduced once its structure was destroyed while shear behavior of the loess showed little change strength parameter c was much more sensitive to structure of the loess than shear strength reduction of the loess due to change of structure should be largely attributed to breaking up of cementation bonds between particles evidenced by the difference in pore size distribution and microstructure of soil fabrics between the undisturbed and remolded samples the bonds provided by clays and carbonates contributed the most to structure of the loess with minor by soluble salts while matric suction played little role in structure of the loess

evaluation of wasatch fault segmentation and slip rates using lake bonneville shorelines 1 analysis of lake bonneville shorelines using lidar digital elevation data challenges accepted models of wasatch fault deformation since the late pleistocene while footwall deformation of the weber segment of the wasatch fault is consistent with back rotation of the footwall block and greatest displacement rate toward the center of the segment shorelines along the footwall of the salt lake city segment decrease in elevation toward the interior and are highest at the segment boundaries an opposite pattern of footwall deformation than predicted for boundaries arresting or strongly inhibiting displacement during earthquakes the spatial pattern of footwall rebound implies that some of the proposed persistent fault segment boundaries do not stop earthquake ruptures that originate on adjacent fault segments nor constrain ruptures initiated within the salt lake city segment net vertical fault displacement at the boundary between the salt lake and provo segments is 16 20 m over the past 16 3 18 5 ka corresponding to a vertical displacement rate of 0 8 1 2 mm yr a net fault slip rate of 2 0 2 8 mm yr and horizontal extension rate of 1 8 2 6 mm yr on the 25 west southwest dipping fault that forms the southern salt lake city segment boundary shoreline analysis suggests isostatic rebound caused by a drop in lake level was concentrated during a relatively short 2000 year time period following the bonneville flood at 16 ka lidar derived topography in conjunction with robust geomorphic datums improves our ability to map deformation associated with lithospheric flexure and faulting while demonstrating the limitation of lacustrine shorelines in this type of analysis

segmentation of the 2010 maule chile earthquake rupture from a joint analysis of uplifted marine terraces and seismic cycle deformation patterns abstract the segmentation of major fault systems in subduction zones controls earthquake magnitude and location but the causes for the existence of segment boundaries and the relationships between long term deformation and the extent of earthquake rupture are poorly understood we compare permanent and seismic cycle deformation patterns along the rupture zone of the 2010 maule earthquake m8 8 which ruptured 500 km of the chile subduction margin we analyzed the morphology of mis 5 marine terraces using lidar topography and established their chronology and coeval origin with twelve luminescence ages stratigraphy and geomorphic correlation obtaining a virtually continuous distribution of uplift rates along the entire rupture zone the mean uplift rate for these terraces is 0 5 m ka this value is exceeded in three areas which have experienced rapid emergence of up to 1 6 m ka they are located at the northern central and southern sectors of the rupture zone referred to as topocalma carranza and arauco respectively the three sectors correlate with boundaries of eight great earthquakes dating back to 1730 the topocalma and arauco sectors located at the boundaries of the 2010 rupture consist of broad zones of crustal warping with wavelengths of 60 and 90 km respectively these two regions coincide with the axes of oroclinal bending of the entire andean margin and correlate with changes in curvature of the plate interface rapid uplift at carranza in turn is of shorter wavelength and associated with footwall flexure of three crustal scale normal faults the uplift rate at carranza is inversely correlated with plate coupling as well as with coseismic slip suggesting permanent deformation may accumulate interseismically we propose that the zones of upwarping at arauco and topocalma reflect changes in frictional properties of the megathrust resulting in barriers to the propagation of great earthquakes slip during the 1960 m9 5 and 2010 events overlapped with the 90 km long zone of rapid uplift at arauco similarly slip in 2010 and 1906 extended across the 60 km long section of the megathrust at topocalma but this area was completely breached by the 1730 m 9 event which propagated southward until carranza both arauco and topocalma show evidence of sustained rapid uplift since at least the middle pleistocene these two sectors might thus constitute discrete seismotectonic boundaries restraining most but not all great earthquake ruptures based on our observations such barriers might be breached during multi segment super cycle events

loess geohazards research in china advances and challenges for mega engineering projects 2019 loess is a meta stable cemented assemblage of mainly silt and clay sized particles of low plasticity when dry it behaves like a brittle material but when wetted up the fabric rapidly collapses unique geomorphological features include extensive surface erosion soil piping loess karst catastrophic landslides and widespread collapse hydro consolidation the chinese loess plateau is a more or less continuous drape of thick loess covering some 440 000 km2 it is one of china s regions that is most prone to geohazards this paper reviews advances in the research related to loess geohazards drawing particular attention to the need to apply research findings to recent very large mega construction projects in loess terrain such as the mountain excavation and city construction in yan an levelling 78 km2 for urban expansion the lanzhou new district creating 246 km2 of new level ground for construction and large engineered interventions in the landscape for gully control and land reclamation such as those in shaanxi and gansu generating agricultural land covering an area of some 8000 km2 these projects are in response to increasing pressures to facilitate expansion of urban centres their interconnecting infrastructures and their agricultural support systems it is argued that where proper application of scientific knowledge for engineering control e g densification drainage of these new landscapes is absent these projects could generate a substantial and costly geohazard legacy for future generations

differential uplift along the northern margin of the central anatolian plateau inferences from marine terraces abstract emerged marine terraces and paleoshorelines along plate margins are prominent geomorphic markers that can be used to quantify the rates and patterns of crustal deformation the northern margin of the central anatolian plateau has been interpreted as an actively deforming orogenic wedge between the north anatolian fault and the black sea here we use uplifted marine terraces across principal faults on the sinop peninsula at the central northern side of the pontide orogenic wedge to unravel patterns of quaternary faulting and orogenic wedge behavior we leveled the present day elevations of paleoshorelines and dated marine terrace deposits using optically stimulated luminescence osl to determine coastal uplift the elevations of the paleoshorelines vary between 4 0 2 and 67 1 4 m above sea level and osl ages suggest terrace formation episodes during interglacial periods at ca 125 190 400 and 570 ka corresponding to marine isotopic stages mis 5e 7a 11 and 15 mean apparent vertical displacement rates without eustatic correction deduced from these terraces range between 0 02 and 0 18 mm a with intermittent faster rates of up to 0 26 mm a we obtained higher rates at the eastern and southern parts of the peninsula toward the hinterland indicating non uniform uplift across the different morphotectonic segments of the peninsula our data are consistent with active on and offshore faulting across the sinop peninsula when integrated with regional tectonic observations the faulting pattern reflects shortening distributed over a broad region of the northern margin of the central anatolian plateau during the quaternary

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

river incision circulation and wind regime of pleistocene lake bonneville usa abstract pleistocene lake bonneville of the western u s and its associated alluvial systems present a unique opportunity to understand the relationship between prevailing winds of the time lake circulation and river incision the lake underwent a catastrophic flooding event 18 300 yr b p resulting in the incision of streams entering the lake along its eastern border incision patterns of twelve streams and rivers suggest that they were influenced by the prevailing circulation in the lake at the time in order to match patterns of river incisions simulations of lake circulation were performed with a state of the art numerical model for the maximum transgressive bonneville lake elevation simulations were conducted using the forcing of westerly and easterly prevailing winds simulated circulation can be described in terms of simple geostrophic balances in which the currents are generally cyclonic counter clockwise for westerly winds and anti cyclonic clockwise for easterly winds irregularities in lake shorelines and bathymetry cause localized variation of this general pattern comparison of model output with the deflected stream incision patterns suggest that prevailing winds during the pleistocene in the great basin of north america were westerly and that unlike the interior of north america the continental ice sheet did not exert significant influence on the climatological wind patterns of the great basin

spatial variability and hydrologic evolution of australian lake basins analogue for pleistocene hydrologic change and evaporite formation abstract processes evident in basins across hydrologic gradients from humid to arid regions today provide analogues for systems that may have operated in some individual basins during periods of past hydrologic change thus lakes in humid regions today with low salinity sedimentary facies and with morphology controlled largely by wave action may closely resemble past lacustral pluvial phases experienced in zones which today are relatively arid and saline conversely playas controlled today by groundwater and in some cases subject to defletion may resemble those arid and dune building stages experienced by basins in sub humid regions today as they underwent glacial age desiccation in any such sequence of spatial or temporal gradients from humid to more arid conditions the frequency of basin filling and drying modulates the rate of evaporitive loss of interstitial waters from the exposed basin surface this in turn controls the salinity evolution of the interstitial and local groundwaters the notion of closed systems for terminal lakes while satisfactory for analysis of surface water budgets is quite inapplicable to the evolution of brines where surfacewater groundwater exchange during the high salinity drying stages becomes a controlling factor affecting all salt budgets in these systems evaporites may only be preserved when the sub surface waters have evolved to salinites near saturation for the salts concerned if sub surface waters are frequently diluted by surfacewater groundwater exchange evaporites will not be preserved in the record even though the surface system appears hydrologically closed the process of interstitial water evolution which controls efflorescence deflation and salt weathering exerts a dominating influence on basin geomorphic expression as well as on hydrochemical fractionation

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

east african mid holocene wet dry transition recorded in palaeo shorelines of lake turkana northern kenya rift abstract the wet early to mid holocene of tropical africa with its enhanced monsoon ended with an abrupt shift toward drier conditions and was ultimately replaced by a drier climate that has persisted until the present day the forcing mechanisms the timing and the spatial extent of this major climatic transition are not well understood and remain the subject of ongoing research we have used a detailed palaeo shoreline record from lake turkana kenya to decipher and characterise this marked climatic transition in east africa we present a high precision survey of well preserved palaeo shorelines new radiocarbon ages from shoreline deposits and oxygen isotope measurements on freshwater mollusk shells to elucidate the holocene moisture history from former lake water levels in this climatically sensitive region in combination with previously published data our study shows that during the early holocene the water level in lake turkana was high and the lake overflowed temporarily into the white nile drainage system during the mid holocene 5270 300 cal yr bp however the lake water level fell by 50 m coeval with major episodes of aridity on the african continent a comparison between palaeo hydrological and archaeological data from the turkana basin suggests that the mid holocene climatic transition was associated with fundamental changes in prehistoric cultures highlighting the significance of natural climate variability and associated periods of protracted drought as major environmental stress factors affecting human occupation in the east african rift system

water retention and volumetric characteristics of intact and re compacted loess a laboratory testing program was conducted to investigate the effects of microstructure on the water retention curve wrc and wetting drying induced volume change in loess the axis translation an

slip rate variations on normal faults during glacial interglacial changes in surface loads geologic and palaeoseismological data document a marked increase in the slip rates of the wasatch fault and three adjacent normal faults in the basin and range province during the late pleistocene early holocene epochs the cause of this synchronous acceleration of fault slip and the subsequent clustering of earthquakes during the holocene has remained enigmatic although it has been suggested that the coincidence between the acceleration of slip and the shrinkage of lake bonneville after the last glacial maximum may indicate a causal relationship here we use finite element models of a discrete normal fault within a rheologically layered lithosphere to evaluate the relative importance of two competing processes that affect fault slip postglacial unloading the removal of mass which decreases the slip rate and lithospheric rebound which promotes faster slip we show that lithospheric rebound caused by regression of lake bonneville and deglaciation of adjacent mountain ranges provides a feasible mechanism for the high holocene rates of faulting in the wasatch region our analysis implies that climate controlled changes in loads applied to earth s surface may exert a fundamental control on the slip history of individual normal faults

on the relationship between water flux and hydraulic gradient for unsaturated and saturated clay summary experimental results indicate that the traditional form of darcy s law is not adequate for describing water flow processes in clay media because the observed relationship between water flux and hydraulic gradient can be highly non linear to capture this non darcian flow behavior we propose a new relationship between water flux and hydraulic gradient by generalizing the currently existing relationships the new relationship is shown to be consistent with experimental observations for both saturated and unsaturated conditions in this paper we also develop an empirical relationship between permeability and threshold hydraulic gradient an important measure of non darcian behavior the latter relationship is practically useful because it can reduce the number of parameters whose values need to be determined from experiment data in order to model non darcian behavior how to incorporate the impacts of temperature and electrolyte concentrations into the proposed relationships needs further research

physicochemical mineralogical and geochemical characteristics of lacustrine sediments of the konya basin turkey and their significance in relation to climatic change abstract physicochemical mineralogical and geochemical characteristics of 279 highly calcareous lacustrine sediment samples obtained from a 30 m drilling core in the western part of the great konya basin turkey were studied the sediments have a predominance of silt and clay fractions with a median diameter of 3 5 m vertical changes of the amounts of water soluble components gypsum carbonates and non salt minerals such as quartz feldspars and layer silicates in the sediments suggest that there were climatic changes in the konya basin the dominant clay mineral is smectite followed by kaolinite illite and palygorskite the oxygen isotopic 18 o ratios of six quartz samples from the konya sediments a terra rossa soil beside lake beysehir golu and paleosols at the foot of mt erciyes da ranged from 18 1 to 20 6 the dominant clay minerals and 18 o ratios suggest that part of quartz and coexisting layer silicates is of long range transported and or local aeolian dust origin from arid and semi arid regions such as north africa israel and the surroundings the relatively high deposition rate might be due to aeolian dust input and or the sediment input introduced by the rivers such as the carsamba river from the toros taurus mountains the vertical distributions of electro conductivity amounts of water soluble and non salt components and the gypsum content of the sediments suggest that gypsum rich layers were formed under shallow saline waters possibly associated with warm to hot and dry environments such as the last interglacial epoch and the early holocene the sediments characterized by relatively high amounts of non salt sediments in which gypsum did not accumulate could be deeper water phases formed under the cold and or wet environments such as the glacial epochs

great earthquakes in low strain rate continental interiors an example from se kazakhstan the lepsy fault of the northern tien shan se kazakhstan extends e w 120 km from the high mountains of the dzhungarian ala tau a subrange of the northern tien shan into the low lying kazakh platform it is an example of an active structure that connects a more rapidly deforming mountain region with an apparently stable continental region and follows a known palaeozoic structure field based and satellite observations reveal an 10 m vertical offset exceptionally preserved along the entire length of the fault geomorphic analysis and age control from radiocarbon and optically stimulated luminescence dating methods indicate that the scarp formed in the holocene and was generated by at least two substantial earthquakes the most recent event dated to sometime after 400 years b p is likely to have ruptured the entire 120 km fault length in a m w 7 5 8 2 earthquake the lepsy fault kinematics were characterized using digital elevation models and high resolution satellite imagery which indicate that the predominant sense of motion is reverse right lateral with a fault strike dip and slip vector azimuth of 110 50 s and 317 343 respectively which is consistent with predominant n s shortening related to the india eurasia collision in light of these observations and because the activity of the lepsy fault would have been hard to ascertain if it had not ruptured in the recent past we note that the absence of known active faults within low relief and low strain rate continental interiors does not always imply an absence of seismic hazard

development and evolution of loess vertical joints on the chinese loess plateau at different spatiotemporal scales abstract the vertical joints of aeolian loess are ubiquitous on the chinese loess plateau clp the distribution variability of which mainly depends on the differences in structural characteristics of loess water drivers e g rainfall or irrigation loess strata e g sedimentary depth and microtopography this study conducted extensive field investigation and experiments to enhance the understanding of morphologies cross scale transformation mechanism and structural bases of loess vertical joints lvjs moreover the development and evolution processes of lvjs were refined by considering loess sedimentary dynamics results show that 1 lvjs are the product of diagenesis in loess strata during loess historical sedimentary process 2 the pore concentration zones and vertical tubular channels in loess are the structural bases of forming original vertical joints ovjs at the micro mesoscale which is supported by the results from the three dimensional computing tomography ct scanning and scanning electron microscopy sem tests and 3 the morphologies of lvjs vary with the microtopography at different spatiotemporal scales and is characterized by the cross scale transformation mechanism i e that they could transform up i e an expansion behavior or down i e a degradation behavior at the micro meso and sub macro scales under the influences of dry wet cycles loess pile thickening and exogenic forces besides we also propose the development and evolution mechanism of ovjs in loess from the viewpoint of unsaturated loess which would help understand the loess anisotropic genesis structural evolution preferential flow and the occurrence of geohazards such as landslides and soil erosion

synthetic aperture radar interferometry observations of the m 6 0 orta earthquake of 6 june 2000 nw turkey reactivation of a listric fault we study the coseismic surface displacement field due to the orta earthquake of 6 june 2000 a moderate sized mw 6 0 oblique slip event that took place on a previously unknown fault located about 70 km north of the capital ankara turkey and about 35 km south of the north anatolian fault we use european space agency ers synthetic aperture radar sar data to generate high resolution maps of the surface displacements by a two pass differential sar interferometry method the surface displacement field reaching up to 15 cm line of sight subsidence is captured in several coseismic interferograms from descending orbits and is inverted to determine the source parameters of the earthquake using elastic dislocations on rectangular fault surfaces with a nonlinear minimization procedure based on simulating annealing algorithm modeling of the coseismic interferograms indicates that the earthquake was associated with a shallow 6 km left lateral oblique normal displacement that occurred on a north south striking eastward dipping listric fault trending at a high angle to the plate boundary right lateral strike slip north anatolian fault careful analyses of multiple interferograms together with the field observations allow us to infer the rupture geometry in fine detail modeling shows that coseismic slip occurs nearly only on the lower portion of the listric fault at a centroid depth of about 5 km but partially reaches to the surface along the surface trace of the dodurga fault in agreement with the field observations we show that in the absence of field observations additional measurements or multiple interferograms that capture the surface deformation from different look angles sar interferometry alone may not be sufficient to constrain earthquake rupture geometry if there is no clear surface faulting the results suggest that the dodurga fault developed most probably as a result of a restraining bend along the north anatolian fault and its left lateral kinematics is consistent with the stress regime that favors the right lateral north anatolian fault

uncharted seismic risk the potential for earthquakes along the plate boundaries has been mapped with reasonable success our attention should now focus on the threat posed by unanticipated quakes located in the continental interiors

the p wave velocity structure near the base of the mantle travel times from 16 events recorded at two temporary networks of short period seismometers deployed across australia have been used to study the p wave velocity structure of the mantle below depths of 1700 km the slowness distance curve derived from these times shows small deviations from the slownesses predicted from the preliminary reference earth model of dziewonski and anderson 1981 that may be significant the most important feature is a rapid decrease of more than 0 5 s degree between distances of 85 and 88 velocity filtering of seismograms from 5 nuclear explosions in kazakh recorded at these australian networks indicates the presence of two arrival branches at distances between 83 and 91 whose slownesses differ by 0 40 to 0 55 s degree and which intersect at a distance of 87 processed p wave seismograms from the yellowknife array in canada also indicate the presence of a similar phenomenon in the same distance range in two separate regions the results can be explained by a widespread rapid or sharp increase in velocity of 2 5 to 3 0 about 200 km above the core mantle boundary

late quaternary alluvial fans of emli valley in the ecemis fault zone south central turkey insights from cosmogenic nuclides abstract alluvial fans within the paraglacial ecemis river drainages on the aladaglar mountains in south central turkey were studied using geomorphological sedimentological and chlorine 36 terrestrial cosmogenic nuclide tcn surface exposure dating methods to examine the timing of alluvial fan abandonment incision and to understand the role of climatic and tectonic processes in the region these alluvial fan complexes are among the best preserved succession of alluvial fans in turkey and they were offset by the major strike slip ecemis fault of the central anatolian fault zone the alluvial fans are mostly composed of well lithified limestone cobbles 5 to 25 cm in size and comprise crudely stratified thick beds with a total thickness reaching up to about 80 m tcn surface exposure dating indicates that the oldest alluvial fan surface yalak fan was likely formed and subsequently abandoned latest by 136 0 23 4 ka ago largely on the transition of the penultimate glaciation marine isotope stage 6 mis 6 to the last interglacial mis 5 i e termination ii the second set of alluvial fan emli fan was possibly developed during the last interglacial mis 5 and incised twice by between roughly 97 0 13 8 and 81 2 13 2 ka ago a younger alluvial fan deposit placed on relatively older erosional terraces of the emli fan suggests that it may have been produced during the last glacial cycle mis 2 these events are similar to findings from other fluvial and lacustrine deposits throughout central anatolia the incision times of the ecemis alluvial fan surfaces largely coincide with major climatic shifts from the cooler glacial periods to warmer interglacial interstadial conditions this indicates that alluvial fans were produced by outwash sediments of paleoglaciers during cooler conditions and later when glaciers started to retreat due to a major warming event the excess water released from the glaciers incised the pre existing fan surfaces an alluvial fan in the study area was also cut by the ecemis fault highlighting the influence of tectonics on fan development it was offset vertically 35 3 m since at least 97 0 13 8 ka which suggests a 0 36 0 06 mm a 1 vertical slip rate of the fault

seismology tectonic strain in plate interiors arising from r smalley jr m a ellis j paul r b van arsdale nature 435 1088 1090 2005 r smalley et al reply it is not fully understood how or why the inner areas of tectonic plates deform leading to large although infrequent earthquakes smalley et al 1 offer a potential breakthrough by suggesting that surface deformation in the central united states accumulates at rates comparable to those across plate boundaries however we find no statistically significant deformation in three independent analyses of the data set used by smalley et al and conclude therefore that only the upper bounds of magnitude and repeat time for large earthquakes can be inferred at present

a palaeomagnetic study of the sivas basin central turkey crustal deformation during lateral extrusion of the anatolian block abstract the sivas basin is a complex collage of eocene and younger rocks located within the wedge shaped eastern margin of the anatolian block between the dextral north anatolian fault zone and the sinistral eastern anatolian fault zone it has been subject to ongoing deformation by movement of the arabian block into eurasia and concomittant sideways expulsion of the anatolian block post collisional deformation since mid miocene times has been dominated by n s to nw se compression expressed by thrusting and strike slip faulting cretaceous and eocene rocks were magnetically overprinted to variable degrees during the collisional phase although these overprints have since been rotated mostly anticlockwise rocks emplaced during the neotectonic history are high fidelity palaeomagnetic recorders of subsequent block movements regional anticlockwise rotation is recognised across the basin with differential rotation of fault and thrust bounded blocks an absence of perceptible differences between group mean rotations identified from miocene pliocene and quaternary units shows that most regional rotation has been concentrated within the latest phase of the neotectonic history during quaternary times at an average rate of 10 ma commencement of this rotation postdates initiation of the north anatolian fault zone implying that compression following collision was accomodated initially by crustal thickening during late miocene and pliocene times subsequent anticlockwise rotations have resulted from sideways expulsion of blocks to the south of the central anatolian thrust along major ne sw sinistral faults to achieve the crustal shortening resulting from n s compression these fault orientations and their sense of motion are explained by a prandtl model involving deformation of a triangular plastic terrane the anatolian block between two rigid plates eurasia and afro arabia the variations in regional rotation identified by palaeomagnetism show that average contemporary anticlockwise rotation of anatolia revealed by gps data 1 2 ma is achieved by variable and locally large block rotations between major thrusts and strike slip faults

spatial variation of saturated hydraulic conductivity of a loess slope in the south jingyang plateau china abstract water infiltration in loess soils is an important trigger causing landslides in which the hydraulic conductivity of the loess plays an important role by analyzing a soil trench and soil samples from the south jingyang plateau northwest china a loess slope was investigated a horizontal adit in a lishi loess layer was also analyzed using variable head permeability tests the saturated horizontal hydraulic conductivity k h and saturated vertical hydraulic conductivity k v of the loess samples were measured results showed that the majority of the k h values are larger than the k v values indicating that the loess exhibits permeability anisotropy lilliefors test was used to determine the normality of the k h and k v results test results indicate that k h and k v measurements of the loess samples collected in the trench and adit all show log normal distribution while a number of the k h and k v values also reflect a normal distribution geo statistical analysis shows that the spherical model and the gaussian model provide the best fit variograms of k h and k v values along the trench analysis along the adit indicated the opposite results the variogram range values suggest that the spatial correlation of loess k v is greater in the vertical direction in a horizontal plane while the spatial correlation of k h in the adit is greater than that in the vertical direction loess structure rather than randomness decides the spatial variation of k h and k v measurements except for k h variation along the adit which depends on both structural factor and randomness k h and k v values of loess tend to decrease with depth results which can be described by an exponential decay model

high pressure metasediments in central turkey constraints on the neotethyan closure history 1 the distribution of oceanic domains and continental blocks in central anatolia remains a challenge in understanding the alpine geodynamic evolution of the tethys realm the consumption of a neotethys oceanic branch at the mesozoic cenozoic boundary welded the central anatolian crystalline complex in central turkey and the anatolide tauride block in western turkey with the northerly eurasian margin whether those two regions constituted a single or two distinct continental masses is still matter of debate high pressure metamorphism has been locally evidenced in the afyon zone which was however defined as a greenschist facies metamorphic zone of the anatolide tauride block since the afyon zone composes a metamorphic equivalent of a continental margin exposed far south of the izmir ankara suture zone this encouraged us to reevaluate its metamorphic evolution in order to better understand the relation between western and central turkey our investigations reveal that the high pressure minerals fe mg carpholite and glaucophane are present in the entire afyon zone which we reconsider as a blueschist facies zone we additionally present a tectonic reconstruction stripping off the postcollisional tectonics it reveals that today s bending of the high pressure belt is consistent with an eocene collision of the anatolide tauride block around the southern edge of the central anatolian crystalline complex we argue that the central anatolian crystalline complex and the anatolide tauride block were two distinct continental masses separated by a neotethyan oceanic stripe the closure of which engendered subduction related metamorphism in the latter and arc volcanism and high grade metamorphism in the former by late cretaceous to early cenozoic

the dune systems of the konya plain turkey their relation to environmental changes in central anatolia during the late pleistocene and holocene abstract several sand flats located on the northern shores of the late pleistocene palaeolake of the konya plain inner anatolia turkey are related to changes in lake levels in this paper the two main dune systems are mapped according to their geomorphological sedimentological and dynamic characteristics and their significance is discussed with regard to the environmental changes since the late pleistocene both at time of the former lake and during the drier periods of the holocene cross sections show the relationship of the dunes to the topography of the basement analyses of the sand fraction show distinct characteristics in size distribution quartz and shell contents wind erosion effects on the quartz grains and petrographic composition interpretation of the results coupled with information provided by the geomorphology of the dune systems studied in the field and from aerial photographs and satellite images highlights the importance and variations in time of local factors such as prevailing winds sand sources changes in lake levels and vegetation a chronology of the main sand fields is proposed based on the evidence of three main droughts during the upper pleistocene the older one much eroded maximum height 3 m covers a limestone surface at 50 m above the bottom of the dried lake an optical scanning luminescence osl date shows a last period of accumulation at 14 328 3220 years the younger one maximum height 12 m has moved over the emerged late pleistocene lacustrine marls an osl date gives an age of 5674 988 years for the last accumulation period evidence of very recent activation of this younger dune system is apparent as a result of overgrazing and excessive land reclamation a third period of dominant wind action and dune construction is responsible for the installation of a younger and thin dune field over the mid holocene lacustrine deposits of the karapinar lake the success of the stabilization programme of the dunes over the last 30 years shows that the last period of dune movement is not related to climate change but to overpressure on the land due to the needs and activities of an increasing population

multi phased uplift of the southern margin of the central anatolian plateau turkey a record of tectonic and upper mantle processes abstract uplifted neogene marine sediments and quaternary fluvial terraces in the mut basin southern turkey reveal a detailed history of surface uplift along the southern margin of the central anatolian plateau from the late miocene to the present new surface exposure ages 10be 26al and 21ne of gravels capping fluvial strath terraces located between 28 and 135 m above the goksu river in the mut basin yield ages ranging from ca 25 to 130 ka corresponding to an average incision rate of 0 52 to 0 67 mm yr published biostratigraphic data combined with new interpretations of the fossil assemblages from uplifted marine sediments reveal average uplift rates of 0 25 to 0 37 mm yr since late miocene time starting between 8 and 5 45 ma and 0 72 to 0 74 mm yr after 1 66 to 1 62 ma together with the terrace abandonment ages the data imply 0 6 to 0 7 mm yr uplift rates from 1 6 ma to the present the different post late miocene and post 1 6 ma uplift rates can imply increasing uplift rates through time or multi phased uplift with slow uplift or subsidence in between longitudinal profiles of rivers in the upper catchment of the mut and ermenek basins show no apparent lithologic or fault control on some knickpoints that occur at 1 2 to 1 5 km elevation implying a transient response to a change in uplift rates projections of graded upper relict channel segments to the modern outlet together with constraints from uplifted marine sediments show that a slower incision uplift rate of 0 1 to 0 2 mm yr preceded the 0 7 mm yr uplift rate the river morphology and profile projections therefore reflect multi phased uplift of the plateau margin rather than steadily increasing uplift rates multi phased uplift can be explained by lithospheric slab break off and possibly also the arrival of the eratosthenes seamount at the collision zone south of cyprus

investigation of sinkholes spatial distribution using the weights of evidence method and gis in the vicinity of karapinar konya turkey abstract there are many sinkholes 182 in the vicinity of karapinar approximately 20 large sinkholes 10 m in diameter were formed within the obruk plateau between 1970 and 2012 the formation of sinkholes is the most important geological hazard in the study area because they can damage engineering structures settlements agricultural areas and eventually be a source of casualties to date no study has been conducted on the distribution of sinkholes in this region in this study the spatial distribution of the sinkholes and the factors controlling sinkhole development were studied through the use of geographical information systems using a sinkhole inventory and a spatial database containing information on the topography geology hydrogeology and land use initially 182 sinkholes were identified in the area by examining the digital elevation model produced for this study the sinkholes were verified in the field thirty two factor maps were produced to investigate their relationship with sinkholes using the weights of evidence method the sinkholes are mainly related to dissolution of the neogene age lacustrine insuyu formation consisting of limestone and clayey limestone sinkhole frequency increases in the vicinity of drainages 2000 3000 m and faults

deformation of western turkey from a combination of permanent and campaign gps data limits to block like behavior 1 we present a new geodetic velocity field covering western turkey south of the north anatolian fault our velocity field is derived from a combination of continuously recording gps stations operating since 2003 survey type gps measurements carried out in the period 1997 2005 and velocities from reilinger et al 2006 the velocity field indicates that western turkey currently undergoes extension whose rate increases from the anatolia plateau to the aegean coast the overall extension in westernmost turkey is about 20 mm yr making it one of the fastest areas of continental extension in the world we test whether the observed deformation is better represented by the rotation of crustal blocks or by more distributed deformation while no deformation is detected in the central anatolian plateau we observe a deformation field west of the plateau that cannot be explained by block models unless the blocks are so small as to be essentially indistinguishable from a continuum although concentration of strain rates up to 140 nstrain yr are found across the major grabens strain rates above 50 nstrain yr are found throughout western turkey the distributions of topography and crustal thickness in western turkey agree with the distributions expected if the crust there had a constant thickness at 5 ma equal to that of the present central anatolian plateau and had subsequently been thinned at the present day distribution of strain rates our results therefore suggest that extensional strain affects the whole continental lithosphere of western turkey rather than being restricted to a small number of block boundaries

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

convergence history across zagros iran constraints from collisional and earlier deformation the zagros orogen provides a unique opportunity within the alpine system to evaluate the interplay between a young tertiary collision and earlier subduction obduction processes within the crush zone and the sanandaj sirjan internal zone separating the zagros fold belt from central iran we document several major tectonic events taking place at the end of the cretaceous of the eocene and from the mio pliocene onwards ca 20 15 ma contrary to recent interpretations our data cross sections and description of the overall deformation style strongly suggest that the main zagros thrust mzt is deeply rooted possibly to moho depths and that the suture zone effectively runs along the mzt field observations show that the final resorption of the oceanic domain took place slightly after 35 ma and that collision must have started before ca 23 25 ma in northern zagros the shortening rate across the crush zone since the mid miocene 20 15 ma is estimated at a minimum 3 4 mm year shear movements in the crush zone during the eocene oligocene period and extensional strike slip movements in the internal zones during the late cretaceous point to an oblique setting early in the convergence history a geotectonic scenario for convergence from the time of obduction to the present is finally proposed

from pleniglacial to holocene a 14c chronostratigraphy of environmental changes in the konya plain turkey abstract in the endoreic semi arid konya basin on the central anatolian plateaux long term hydrological evolution has left various landforms and lacustrine deposits reflecting the regional climatic evolution as well as human influence on the local environments this paper presents results from a cooperative programme grouping several institutes from turkey and france on lacustrine marshy and aeolian sediment sequences of upper pleistocene and holocene age the detailed study of environmental evolution is based on the reconstruction as well as on the characterization of the extension and contraction phases of wetlands occupying the lowest parts of the konya plain a soil and a marsh layer are 14c dated ca 28 000 25 000 yr bp three phases of pleniglacial from ca 22 000 to 17 000 yr bp high lake levels are distinguished complementary osl dates on aeolian dunes confirm the occurrence of two drought periods the first occurs around the start of the late glacial the second after the mid holocene climatic optimum the latter being in phase with a similar drought in other eastern mediterranean regions after 17 000 yr bp no lacustrine phase reached as high a level as the pleniglacial lake during the late glacial a shallow freshwater lacustrine phase is identified from 12 500 to 11 000 yr bp the late glacial to holocene transition corresponds to a general absence of deposits and dateable material thus suggesting a period of drought to which no aeolian features have so far been related the holocene environmental evolution shows a period of marsh and shallow lake extansion from 6000 to 5500 yr bp this wetter period is interrupted by the second drought ca 5500 yrs bp as indicated by aeolian dune activity during the late holocene a renewal of marshes as well as soil development on slopes can be interpreted either as climatic changes or as impacts of human use of water and soil resources during prehistoric and historic times

tectonic implications of fluvial incision and pediment deformation at the northern margin of the central anatolian plateau based on multiple cosmogenic nuclides 1 we document quaternary fluvial incision driven by fault controlled surface deformation in the inverted intermontane gok rmak basin in the central pontide mountains along the northern margin of the central anatolian plateau in situ produced 10be 21ne and 36cl concentrations from gravel covered fluvial terraces and pediment surfaces along the trunk stream of the basin the gok rmak river yield model exposure ages ranging from 7 1 ka to 346 45 ka and average fluvial incision rates over the past 350 ka of 0 28 0 01 mm a 1 similarities between river incision rates and coastal uplift rates at the black sea coast suggest that regional uplift is responsible for the river incision model exposure ages of deformed pediment surfaces along tributaries of the trunk stream range from 60 5 ka to 110 10 ka demonstrating that the thrust faults responsible for pediment deformation were active after those times and were likely active earlier as well as explaining the topographic relief of the region together our data demonstrate cumulative incision that is linked to active internal shortening and uplift of 0 3 mm a 1 in the central pontide orogenic wedge which may ultimately contribute to the lateral growth of the northern anatolian plateau

the north anatolian fault zone distributed neogene deformation in its northward convex part abstract the north anatolian fault zone is composed of two almost rectilinear branches which join in a northward convex bend in this bent zone the pontide anatolide collisional system has been cut across by two transpressional belts of fold and thrust and wrench faults of lower neogene age these structures were reactived during the neotectonic period the time of deposition of the pontus group for both of these deformational events and up to the present the tectonic regime remained generally transpressional with a nw se direction of compression and a ne sw direction of extension it is only recently during the upper pleistocene that the dextral wrench faults became more localized and more straight than previously the complexity of the eastern part of the north anatolian fault zone is better understood if one takes into account the role of inherited miocene pliocene transpressional structures

coeval extension and compression in late mesozoic recent thin skinned extensional tectonics in central anatolia turkey abstract the central anatolian crust is composed of high grade metamorphic rocks covered by tertiary shallow marine to continental sedimentary rocks with a middle miocene recent volcanic activity in cappadocia after the late cretaceous closure of the tethyan ocean and following plate collision core complexes formed in nigde and kirsehir regions of central anatolia recent geophysical studies indicate the presence of low seismic velocity zones beneath central anatolia interpreted as regionally thinned and or hot mantle lithosphere or asthenospheric upwelling we present new structural data covering a 300 km wsw nne trending transect between konya and yozgat cities to suggest that central anatolian cenozoic tectonic regime is extensional and the narrow fold thrust zones once taken as evidence of crustal convergence resulted from gravitational movements curie point depths map of central anatolia shows a large scale diameter 140 km upwarping c 15 km of the regional crust we interpret as due to asthenospheric upwelling these considerations suggest that 1 the central anatolian crust deforms by extension transcurrent faults like the central anatolian fault zone accommodate the crustal stretching by transfer faulting 2 post late cretaceous crustal extension favored the placement of hot and low density asthenospheric material in cappadocia by processes that may be explained by rayleigh taylor instability phenomenon 3 in central anatolia large post eocene horizontal crustal displacements we estimate a minimum of 50 km are not achieved by crustal contraction as previously proposed but thin skin extensional tectonics and 4 tethyan suture lines need to be reviewed since their traces may be modified by later extensional displacements

turkish karst aquifers one third of turkey s surface is underlain by carbonate rocks that have been subdivided into four karst regions the carbonate rock units are about 200 km wide along the taurus mountains that attain elevations of 2500 m karst features of western turkey bordering the aegean and mediterranean seas demonstrate the tectonic lithological and climatic controls on the occurrence movement and chemical characteristics of groundwater in turkey all karstic feature such as lapies caves sinkholes uvalas poljes ground river valleys developed in all karstic areas karstification is related not only to the thickness and to purity of limestone climate and height but also to tectonic movements water resources of karst terrains of turkey are relatively rich and as such are very important for the economic development of the country high mountain chains very often associated with the karst terrains are responsible for some important and beneficial characteristics of these water resources four karst regions are 1 taurus karst region 2 southeast anatolia karst region 3 central anatolia karst region and 4 northwest anatolia and thrace karst regions

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

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

effective elastic thickness variations along the andean margin and their relationship to subduction geometry 1 we present a new map of the spatial variations in effective elastic thickness te along the andes estimated using bouguer coherence the te variations reflect interactions between subducting slab and preexisting terrane structure in the forearc conductive cooling of the continent by the subducting slab exerts primary control on rigidity resulting in te that is highest 40 km where the oceanic lithosphere is oldest and coldest 20 s in the central andes te is relatively low 20 km along the volcanic chain and the altiplano and puna plateaus we interpret this weakening to reflect a high geothermal gradient maintained by advective magmatic processes a shallow and hot asthenosphere and a very weak lower crust throughout this region east of the plateaus high te delineates underthrusting of the brazilian shield finally north and south of the plateaus flat subduction areas are characterized by high te high shear wave velocity thick thermal lithosphere and low heat flow indicating that continental lithosphere there is thicker colder and stronger on the basis of these relationships we suggest that variations in slab dip along the margin relate to variations in structure of the continental lithosphere in particular we propose that upper plate structure influences the width and viscosity of the asthenospheric wedge which control the suction moment responsible for the subduction angle at depths 70 100 km for example when oceanic lithosphere subducts beneath thin continental lithosphere the low viscosity asthenosphere allows the slab to detach from the continent and sink into the mantle at normal angles however when oceanic lithosphere subducts close or beneath thick and strong continental lithosphere the asthenospheric wedge narrows and corner flow drags high viscosity mantle from the base of the thick 150 km cold continent into the wedge suction forces increase with both narrowing of the wedge and its increasing viscosity we estimate the asthenospheric viscosity underneath thick cold continents to be 1020 pa s sufficient to induce flat subduction later after prolonged hydration and weakening of the continent s base asthenospheric flow into the wedge may resume allowing the slab to sink again into the mantle at normal angles

late pleistocene piedmont glaciations in the eastern mediterranean insights from cosmogenic 36cl dating of hummocky moraines in southern turkey abstract we report the presence of late pleistocene piedmont glaciers represented by the largest hummocky moraine field observed in the eastern mediterranean the piedmont glaciers originated from the geyikdag ice cap 40 km 2 situated between 2350 and 2650 m above sea level a s l central tauride mountains of turkey and deeply carved the north facing hillslopes before reaching the namaras valley 2000 2050 m a s l the hummocky moraines resulted from in situ deposition of stagnant glacier ice where debris cover was heterogeneously distributed on the glacier surface thirty four boulders from hummocky disintegration lateral and terminal moraines from the namaras valley and the tributary susam valley 2100 2200 m a s l were dated by cosmogenic 36 cl surface exposure dating the moraine ages indicate three phases of deglaciation during the late pleistocene the oldest deglaciation occurred in the namaras valley at 18 0 1 1 ka ka thousand years ago towards the end of the last glacial maximum lgm and is recorded entirely by hummocky moraines we speculate that hummocky moraine forming processes with cycles of relief inversion gave rise to boulder apparent ages up to a few thousand years younger in our study area therefore 18 0 1 1 ka should be regarded as a minimum age with a probable true age much closer to the local lgm values 20 ka as observed in the surrounding mountains paleo piedmont glaciers also deposited several lateral moraines that are 50 m higher than the hummocky moraines although the lateral moraines probably represent the build up and the hummocky moraines the final phase of the same local lgm pulse both lateral moraines started to retreat from the late glacial 14 0 2 7 ka and gradually disappeared by mid holocene 5 2 1 0 ka encompassing the younger dryas yd stadial in the susam valley the late glacial is represented by a terminal moraine 13 4 1 5 ka the glacier retreat was very fast as indicated by an almost instantaneous disappearance of 5 km long susam valley glacier represented by disintegration and hummocky moraines 14 0 1 3 ka alternatively in case the oldest boulder age is taken into account the susam valley glacier can be also attributed to the late lgm 17 ka to late glacial 14 ka transition near the exit of the susam valley a right lateral moraine was deposited 11 6 1 3 ka ago confirming the presence of the yd in geyikdag comparable glacial chronologies were obtained from other turkish and mediterranean mountains

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

distribution and characteristics of landslide in loess plateau a case study in shaanxi province abstract every year about one third of the geohazards in china occur in the loess plateau causing human loss damaging gas and oil pipelines destroying highways railways and degrading farmland field investigation and monitoring in situ tests and laboratory experiments were performed to improve our understanding of the factors effecting the distribution characteristics and causes of loess landslides first we find that 79 of the landslides are shallower than10m 85 have a volume of less than 100 000 m3 second landslides on the loess plateau occur primarily on concave slope profiles that have slope angles of 20 35 and that face south east third the equivalent coefficient of friction of loess landslides is very low resulting in long run out with a low angle sliding surface loess landslides generally transform into mud flows resulting in an increase in volume in transit and forming a geohazard chain antecedent rainfall plays an important role in triggering loess landslides finally clusters of landslides in the loess plateau occur because the loess easily disintegrates under high pressure due to its loose and highly porous structure there is a sharp decrease in cohesive strength with increase in deformation and water content and thus landslides tend to undergo static liquefaction during sliding

optimization of compaction zoning in loess embankments extensive centrifuge model tests were carried out to investigate optimum compaction density zones within loess embankments 30 and 63 8 m high in these tests water infiltration into the slopes and upstream storm water ponds were modelled to simulate the most unfavourable working conditions displacement contours in the cross sections were measured and crest settlements were monitored during the tests finally the optimum compaction zoning was analysed based on the comprehensive evaluation of the total crest settlement the postconstruction settlement and the slope stability of the embankments it was indicated that a properly designed high loess embankment could perform satisfactorily with the lower part compacted looser than the conventional code requirements in terms of total crest settlement and embankment cracking the degree of compaction k of loess fills should not be less than 0 85 for 30 m high embankments and not less than 0 90 for 63 8 m high embankments in terms of the postconstruction settlement 0 2 0 3 m and construction feasibility it is expedient to compact the lower one third to k 0 85 and the top two thirds to k 0 90 for 63 8 m high embankments for 30 m high embankments the bottom zone with k 0 85 can make up two thirds of the height

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

surface exposure dating of late pleistocene glaciations at the dedegol mountains lake beysehir sw turkey situated on the interior side of the western central taurus mountains of sw anatolia the muslu valley in the dedegol mountains mt dipoyraz 37 37 07 n 31 19 42 e 2992 m above sea level a s l represents the lower part of a formerly glaciated valley system of 7 5 km in length surface exposure ages with cosmogenic 10be and 26al date a glacier expansion out of the muslu valley 24 3 1 8 ka ago 1 confidence interval and give evidence for pronounced glacier advances prior to the global last glacial maximum lgm 21 2 ka deglaciation commenced no later than 17 7 1 4 ka ago superimposed climatic oscillations are indicated by glacier fluctuations dated around 19 8 1 6 ka and again 13 9 2 3 ka prior to the first major amelioration of climate the late pleistocene glacier chronology from the western central taurus mountains published lake level fluctuation data of palaeolake konya and lake beysehir and nearby pollen data on the central anatolian plateau reveal a conspicuous time correlation of palaeoenvironmental change copyright 2009 john wiley sons ltd

active tectonics of the andes nearly 90 mm a 1 of relative plate convergence is absorbed in the andean plate boundary zone the pattern of active tectonics shows remarkable variations in the way in which the plate slip vector is partitioned into displacement and strain and the ways in which compatibility between different segments is solved along any traverse across the plate boundary zone the sum of relative velocities between points must equal the relative plate motion we have developed a kinematic synthesis of displacement and strain partitioning in the andes from 47 s to 5 n relevant for the last 5 ma based upon 1 relative plate motion deduced from oceanic circuits giving a roughly constant azimuth between 075 and 080 2 moment tensor solutions for over 120 crustal earthquakes since 1960 3 structural studies of deformed plio pleistocene rocks 4 topographic geomorphic studies 5 palaeomagnetic data and 6 geodetic data we recognize four neotectonic zones with subzones and boundary transfer zones that are partitioned in different ways these zones are not coincident with the classic zones defined by the presence or absence of a volcanic chain or differences in finite displacements and strains and tectonic form the long term segmentation and finite evolution of the andes may not occur in constantly defined segments in space and time in segment 1 47 39 s the slip vector is partitioned into roughly orthogonal benioff zone slip with large magnitude large slip surface earthquakes and both distributed dextral shear giving clockwise rotations of up to 50 and dextral slip in the curved liquine ofqui fault system giving 5 10 of anticlockwise fore arc rotation in segment 2 39 20 s the slip vector is partitioned into benioff zone slip roughly parallel with the slip vector andean crustal shortening and a very small component of dextral slip including that on the atacama fault system between 39 and 34 s a cross strike dextral transfer which deflects the chile trench and the volcanic arc absorbs the shortening contrast between segments 1 and 2 in segment 3 20 6 s the slip vector is partitioned into roughly orthogonal benioff zone slip crustal shortening sinistral trench parallel faulting and northeast southwest extension compatibility between segments 2 and 3 is maintained by the sinistral east southeast trending cochabamba shear zone and north trending dextral faults in segment 4 6 s to 5 n the slip vector is partitioned into roughly orthogonal benioff zone slip and dextral strike slip faulting in the fore arc and volcanic chain

crustal strength in central tibet determined from holocene shoreline deflection around siling co abstract controversial end member models for the growth and evolution of the tibetan plateau demand quantitative constraints of the lithospheric rheology direct determinations of bulk crustal rheology however remain relatively sparse here we use the flexural rebound of lacustrine shorelines developed during the lingtong highstand around siling co in central tibet to place bounds on the effective elastic thickness t e and viscosity of tibetan crust shoreline features associated with the lingtong highstand complex 60 m above present lake level are deflected from horizontal by 2 4 m over wavelengths of 200 km optically stimulated luminescence dating of aggradational shoreline deposits indicates that these lake levels were reached at 6 4 ka assuming that surface loads were entirely supported by an elastic layer overlying an inviscid fluid the range and spatial distribution of variations in shoreline elevation are consistent with deflections predicted by a uniform elastic plate with thickness t e of 20 30 km if viscoelastic relaxation in response to lake withdrawal is complete our data suggest an average viscosity 10 19 pa s these results imply that the apparent viscosity of the lower crust inferred over millennial timescales is comparable with that estimated from post seismic relaxation over decadal timescale