sea cliffs their processes profiles and classification general concavity or convexity of sea cliff profiles is controlled by relative rates of erosion by marine and subaerial processes as well as by positions of more resistant strata in the cliffs profiles supplemented by on site examination can establish the activity and dominance of erosional processes and indicate changes in regimen a sharp angle at the sea cliff base generally indicates active marine erosion whereas a smooth curve at the base means that subaerial erosion may dominate talus shows absence of marine erosion studies of profiles can be useful for estimating stability for residences railroads and highways at the top face and base of sea cliffs generally increased erosion and retreat of sea cliffs are in prospect because of projected regionally wetter and stormier climate rising sea level and increased human activities

crystal fractionation of adakitic magmas in the crust mantle transition zone petrology geochemistry and u pb zircon chronology of the seme adakites eastern pontides ne turkey abstract plutonic and porphyritic intrusions of adakitic rocks are widely distributed in the southern part of the eastern pontides orogenic belt in turkey ranging in age from late paleocene to early eocene these intrusions provide critical information to evaluate the early cenozoic geodynamic evolution of the eastern mediterranean region here we report the results from our field petrologic geochemical and zircon u pb geochronological studies on adakitic intrusions in the seme area from the southern part of eastern pontides belt the seme granitoid daldibi dacite and aslanca dacite porphyry from this region carry abundant plagioclcase amphibole and biotite phenocrysts and have geochemical affinities typical of adakites including high sio2 58 48 75 6 wt al2o3 15 78 18 28 wt na2o 3 94 5 08 wt sr 506 1413 ppm and la 12 6 52 9 ppm moderate k2o 1 77 2 76 wt and low y 4 7 14 2 ppm and yb 0 28 1 29 ppm the early eocene intrusions in the seme area have compositional similarities with high slica adakites and their geochemical features suggest the involvement of slab derived melts the zircons separated from these rocks show euhedral crystal shapes with oscillatory cores typical of crystallization from magmas as also confirmed by their high th u ratios 0 78 to 1 15 u pb analyses of zircons from the quartz diorite yielded a weighted mean 206pb 238u age of 53 16 0 45 ma zircon grains from the aslanca dacite porphyry occurring as a late phase within the seme body show u pb isotopic ages of 53 and 52 ma concordant with u pb ages of zircons from quartz diorite based on major trace and rare earth element data we present a model suggesting crystal fractionation and or differentation processes of subduction related adakitic magmas stored in the crust mantle transition zone and their transfer into shallow depths of the overriding continental lithosphere

analysis of gravity anomalies of sedimentary basins by an asymmetrical trapezoidal model with quadratic density function the decrease of density contrast with depth in many sedimentary basins can be approximated by a quadratic function the interpretation of gravity anomalies over sedimentary strata can be more realistic if variable density contrasts rather than constant density contrasts are assumed i derive the equation for the gravity anomaly of an asymmetrical trapezoidal model assuming a quadratic density function and i develop methods of interpretation using the marquardt algorithm while interpreting a synthetic anomaly profile the convergence of the algorithm is shown by plotting the values of the objective function damping parameter and various parameters of the model with respect to iteration number the results are superior to those obtained when using constant density contrasts in addition i apply the method in the interpretation of gravity anomalies over the san jacinto graben and the lower godavari basin

curie point depth from spectral analysis of magnetic data in erciyes stratovolcano central turkey curie point depth and heat flow values of the erciyes region are determined to identify the thermal regime of the central anatolia by applying the spectral analysis method to the magnetic anomaly data to compute the spectrum of the data the magnetic anomaly of the region is transformed into 2 d fourier domain to attain the average curie depth this method is useful in determining the top boundary of magnetic anomaly sources and reveals the curie depth as 13 7 km in the study area the obtained results imply a high thermal gradient 42 3 c km 1 and corresponding heat flow values 88 8 mwm 2 in the research area using the temperature value measured at borehole drilled by the general directorate of mineral research and exploration of turkey mta the values for the thermal gradient and heat flow value were computed as 50 7 c km 1 106 5 mwm 2 from the heat flow value the curie point depth was determined as 11 4 km in this region it is concluded from the obtained values that the region has very high geothermal potential caused by partial melting of the lower crust

estimation of curie point temperature and geothermal structure of island arcs of japan abstract curie depth analysis from aeromagnetic data was performed in a nationwide project to assess the geothermal resources of japan creation of a curie depth map of japan was completed in 1984 and it agrees well with thermal structures such as the high temperature gradient regions of volcanic chains low temperature regions of the forearc basins and the intermediate temperature regions of the backarc basins measured temperature gradient t data were gathered in order to estimate the curie temperature from the t and the curie depths when t is assumed to be constant with respect to depth a remarkable difference is found in the estimated curie temperature t e c of the backarc and forearc side of the basins in the backarc side an average t e c of 450 c is reasonable for both the curie depth estimated from aeromagnetic data average depth of about 10 km in the backarc side and the temperature gradients average gradient of 4 5 c 100 m the average t e c on the forearc side was found to be low at about 300 c the difference in the curie temperatures between the two areas may be due to a regional difference in rock type e g granite as opposed to basalt in the case of the northeast japan arc as suggested by some authors the isotherms may suddenly fall between the volcanic front and the trench based on model studies we recognized that a curie depth map obtained by the algorithm we developed should include an averaging effect this suggests that the inferred curie depth curve across the line marking the sudden fall in the curie isotherm should gradually increase towards the trench therefore the low curie temperature that we estimated may indicate an apparent shallow curie depth caused by the averaging effect against an area bearing deep curie depths hence the reasons for the inconsistency of the estimated curie temperature between the forearc side and backarc side may be as follows 1 the averaging effect of the curie depth estimate which makes the curie depth apparently shallower in the forearc side and 2 the lower curie temperature of basaltic rocks which are assumed to be distributed along the east side of the aseismic front

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

hydrological characteristics of the drainage system beneath a surging glacier a rare combination of natural circumstances permits assessment of current theories on water flow beneath glaciers outburst floods from the subglacial lake grimsvotn in iceland took place before during and after surging of skei ararjokull the glacier beneath which the outburst floods drain the observable drainage patterns associated with these floods show the different nature of the basal water conduit system of the glacier during surge and non surge phases during surge conditions basal water is dispersed slowly across the bed in a distributed drainage system but when the glacier is not surging water is transported rapidly through a system of tunnels

draining the tangjiashan barrier lake this paper documents the emergency breaching of an approximately 110 m high landslide dam that was created at tangjiashan during the 2008 wenchuan earthquake of china s southwest sichuan province as an emergency measure a 13 m deep channel was excavated to reduce the volume and head of the released water during the dam breaching and to create a controlled flood that was intended to prevent catastrophic consequence for 1 2 million people downstream from detailed monitoring and survey works carried out during and after the dam break it was found that 1 the breaching initiated at a pool water level of 742 1 m with an estimated flow velocity of 2 4 m s and virtually terminated at a pool water level of 720 3 m with an estimated velocity of 2 5 m s which can be regarded as the incipient velocity that initiated erosions for the soils at this particular site 2 a controlled flood released 167 106 m3 reservoir water with a peak flow rate of 6 500 m3 s during which a maximum velocity of about 5 0 m s

meander migration the observation method river meanders migrate over time and the consequences of this migration can create a problem for bridges and embankments near the river this is why it is important to predict the lateral extent of

initiation of the neomagmatism in east anatolia abstract in eastern anatolia the neotectonic episode commenced with the complete elemination of the neo tethyan ocean floor as a result of collision between arabia and eurasia during early miocene time after the collision continuing convergence initiated a new tectonic regime and coeval magmatic activity the post collisional convergence caused crustal shortening and thickening as evidenced by regionwide development of e w trending folds and thrusts and conjugate strike slip faults the related volcanic activity has progressed in three cycles in the initial cycle weakly alkaline volcanic rocks were produced that are known as the solhan volcanics they outcrop at the western end of an e w striking neotectonic depression called the mus basin which constitutes the western prolongation of the lake van basin the basin is a thrust bounded depression that developed out of an original syncline by the disruption of its limbs the lavas of the first cycle reached the surface along n s aligned extensional structures in the second volcanic cycle a widespread k type ca volcanism occurred through crustal contribution during the late miocene early pliocene time when the continuing north south convergence caused substantial shortening and thickening of the continental crust the last volcanic cycle produced a thick volcanic cover consisting of rocks of alkaline affinity during the pleistocene and the quaternary when the thickened crust began to accommodate the ongoing north south shortening by east west extension after the formation of the east and north anatolian transform faults

melting of the glacier base during a small volume subglacial rhyolite eruption evidence from blahnukur iceland abstract although observations of recent volcanic eruptions beneath vatnajokull iceland have improved the understanding of ice deformation and meltwater drainage little is known about the processes that occur at the glacier base we present observations of the products of a small volume effusive subglacial rhyolite eruption at blahnukur torfajokull iceland lava bodies typically 7 m long have unusual conical morphologies and columnar joint orientations that suggest emplacement within cavities melted into the base of a glacier cavities appear to have been steep walled and randomly distributed these features can be explained by a simple model of conductive heat loss during the ascent of a lava body to the glacier base the released heat melts a cavity in the overlying ice the development of vapour escape pipes in the waterlogged permeable breccias surrounding the lava allows rapid heat transfer between lava and ice the formed meltwater percolates into the breccias recharging the cooling system and leaving a steam filled cavity the slow ascent rates of intrusive rhyolitic magma bodies provide ample time for a cavity to be melted in the ice above even during the final 10 m of ascent to the glacier base an equilibrium cavity size is calculated at which melting is balanced by creep closure this is dependent upon the heat input and the difference between glaciostatic and cavity pressure the cavity sizes inferred from blahnukur are consistent with a pressure differential of 2 4 mpa suggesting that the ice was at least 200 m thick this is consistent with the volcanic stratigraphy which indicates that the ice exceeded 350 m in thickness although this is the first time that a subglacial cavity system of this type has been reconstructed from an ancient volcanic sequence it shares many characteristics with the modern firn cave system formed by fumarolic melting within the summit crater of mount rainier washington at both localities it appears that localised heating at the glacier base has resulted in heterogeneous melting patterns despite the different rheological properties of ice and firn similar patterns of cavity roof deformation are inferred the development of low pressure subglacial cavities in regions of high heat flux may influence the trajectory of rising magma with manifold implications for eruptive mechanisms and resultant subglacial volcanic landforms

investigation of rate of erosion of soils in embankment dams the slot erosion test and the hole erosion test have been developed to study the erosion characteristics of soil in cracks in embankment dams the erosion characteristics are described by the erosion rate index which measures the rate of erosion and the critical shear stress which represents the minimum shear stress when erosion starts values of the erosion rate index span from 0 to 6 indicating that soils can differ in their rates of erosion by up to 10 6 times the rate of erosion is shown to be dependent on the soil fines and clay sized content plasticity and dispersivity compaction water content density and degree of saturation and clay mineralogy and possibly the presence of cementing materials such as iron oxides coarse grained noncohesive soils in general erode more rapidly and have lower critical shear stresses than fine grained soils knowledge of the erosion characteristics of the soil in the core of an embankment dam aids in the assessment of the likelihood of dam failure due to piping erosion

improvement of hole erosion test and results on reference soils abstractunderstanding the factors that control the transport of soil particles detached by water is essential in predicting the contingency of internal and surface erosion of embankments during storms and floods it is particularly useful to be able to evaluate the sensitivity of the available soils to erosion at an early stage of a project and the risk assessment of an existing earthwork the presented study is based on laboratory tests with a hole erosion test apparatus and tries to characterize the internal erosion of soils the test consists of eroding a drilled soil specimen by water flow with a constant pressure drop at the boundaries of the specimen while recording the flow rate and studying the hole enlargement a new version of the apparatus with improved instruments and an interpretation method is proposed estimating the erosion rate based on the turbidity of the outflow and independent of hydraulic charge several remolded kaolinite sand mixtures are tested as reference soil textures and the

ash layers from iceland in the greenland grip ice core correlated with oceanic and land sediments four previously known ash layers ash zones i and ii saksunarvatn and the settlement layer all originating in iceland have been identified in the central greenland ice core grip this correlation of the ash between the different environments is achieved by comparison of the chemical composition of glass shards from the ash this establishes and confirms detailed correlations between the different types of depositional records and the absolute dating of the younger part of the ice core by counting annual layers dates the eruptions accurately a precise connection with dates obtained by14c beyond the range of dendrochronology is established which provides an excellent confirmation of230th 234u dates from corals four additional icelandic ash layers have also been identified in the core but not yet correlated with known ash deposits

interpretation of the gravity and magnetic anomalies of the cappadocia region central turkey the cappadocia region located in central turkey is characterized by widespread lava flows and volcanoclastic deposits dating from miocene to quaternary gravity and aeromagnetic anomalies of the region appear to present similar high and low amplitude regions although the aeromagnetic anomalies exhibit a rather complex pattern which is thought to be caused by remanent magnetization the low pass filtered aeromagnetic map shows a deep seated magnetic anomaly which may be linked to the widespread volcanic activity at the surface the pseudogravity transformation of the upward continued anomaly has been constructed the pseudogravity anomaly demonstrates some form of clockwise rotation this anomaly was modelled by means of a three dimensional method the top and bottom of the body are at 6 3km and 11km including the flight height from the ground surface respectively this deep body is ellipsoidal and extends along an e w direction which is in line with the regional stress direction deduced from gps measurements a new mobilistic dynamo tectonic system appears to explain the body s e w elongation the modelled body may be the source for the inferred geothermal energy of the region magnetic measurements were carried out on oriented rock samples collected from outcrops of ignimbrites and basalts providing directions and intensities of remanent magnetization susceptibilities and koeningsberger q ratios standard deviations of remanent directions of the natural remanent magnetization nrm display a wide scatter implying unreliability of the surface data reduction to pole rtp transformation of magnetic anomalies was successful with the induced magnetization angle despite the complex pattern of magnetic anomalies

the combined use of masw and resistivity surveys for levee assessment a case study of the melvin price reach of the wood river levee abstract capacitively coupled resistivity ccr and multichannel analysis of surface waves masw were performed on the melvin price reach of the wood river levee that has experienced considerable piping through the foundation soil causing numerous sand boils along the landside toe of the levee tests were performed along the centerline crest the landside toe and the riverside berm of the levee this study combined the strengths of masw and ccr testing to resolve the distribution and stiffness of cohesive and non cohesive materials in the body and foundation of the levee where invasive testing was not ideal masw and ccr were shown to complement each other in the evaluation ccr successfully classified the near surface clay and sand deposits along the levee and was particularly effective for soil deposits with a high degree of saturation masw revealed that a deeper clay layer appears to be discontinuous at locations where old river bars cross under the levee these bars may have eroded portions of the deeper clay layer locally enhancing seepage rates through the foundation materials and influencing the formation of sand boils during large flood events the use of masw and ccr also successfully detected the locations of the major utilities crossing the levee while ccr was the most effective method for detecting conductive utilities masw was more effective at detecting utilities which increased the overall stiffness of the subsurface either due to the utility itself or the backfill material around the utility a site specific spt vs correlation was developed from the co located boreholes and shear wave velocity profiles comparison of the correlation with previous studies indicates that soil stiffness and geologic age are important factors affecting spt vs correlations for levee soil deposits which are typically young a lower bound spt vs correlation developed using similar soil deposits to the study area should be considered

erosion charts for selected geomaterials abstractknowledge of erodibility is essential to the analysis of problems related to soil erosion including bridge scour embankment and floodwall overtopping dam spillway erosion stream stabilit

gravity and magnetic studies of the subglacial grimsvotn volcano iceland implications for crustal and thermal structure the highly active subglacial grimsvotn volcano is associated with a 20 mgal bouguer gravity high and a broad magnetic low the magnetic low roughly coincides with the gravity high but short wavelength magnetic highs are superimposed on the low especially along caldera rims forward models of the gravity and magnetic fields show variable magnetization 0 12 a m 1 in the uppermost 1 2 km of the crust probably reflecting differences in the proportions of crystalline rocks and hyaloclastites and variations in hydrothermal alteration the models are consistent with but do not require a 10 km3 molten magma chamber in the shallow crust beneath the main caldera between 1 5 and 4 km depth a dense body 2 95 3 0 mg m 3 with a volume of 400 km3 is located probably composed of gabbro modeling suggests that this intrusive body is nonmagnetic which may imply that its temperature is at or above the curie point the distribution of geothermal activity at the glacier bed is consistent with heat extraction from this dense hot intrusive body it may be an important source for the presently observed geothermal heat output of 2000 4000 mw at grimsvotn this high heat transfer rate is difficult to reconcile with estimates of long term heat production in an icelandic rift zone volcano the heat flux may be a transient phenomenon caused by enhanced vertical permeability due to a recent caldera collapse and subsequent heat mining of the intrusive body

crustal model for the middle east and north africa region implications for the isostatic compensation mechanism summary we present a new 3 d crustal model for the middle east and north africa region that includes detailed topography sediment thickness and moho depth values the model is obtained by collecting integrating and interpolating reliable published sedimentary rock thickness and moho depth measurements in the middle east and north africa region to evaluate the accuracy of the model the 3 d gravity response of the model is calculated and compared with available observed bouguer gravity anomalies in the region the gravity modelling shows that the new crustal model predicts large portions of the observed bouguer anomalies however in some regions such as the red sea and caspian sea regions where crustal structure is relatively well determined the residual anomalies are of the order of a few hundred milligals since the new crustal model results in large residual anomalies in regions where reasonably good constraints exist for the model these large residuals cannot simply be explained by inaccuracies in the model to analyse the cause of these residuals further we developed an isostatically compensated airy type moho depth model and calculated its gravity response isostatic gravity anomalies are in nearly perfect agreement with the observed gravity values however the isostatic model differs significantly from the new 3 d crustal model if isostasy is to be maintained crustal and or upper mantle lateral density variations are needed to explain the large observed gravity residuals

variations in the thermal output of the subglacial grimsvotn caldera iceland a 69 year record 1922 1991 of heat release has been obtained from the subglacial geothermal system of the grimsvotn caldera within the vatnajokull ice cap the data were derived from in situ measurements of the volume of meltwater accumulated in the caldera lake subtracting climatically induced melting the overall fluctuations in the heat flux are closely related to volcanic activity and are dominated by a main pulse of 11 600 mw caused by a major eruption in 1938 gradually declining to 1600 mw in 1976 1982 heat extracted from the roof of a magma chamber with the aid of hydrothermal convection may have given a basic contribution to the heat flux of 1500 to 2000 mw an upper bound the variable part of the heat flux from 0 to 10 000 mw was released from magma erupted at the base of the glacier and from shallow intrusions the total heat released over the period 1922 to 1991 was 8 1 1 6 1018j equivalent to the energy released by the solidification and cooling of 2 1 0 4 km of basaltic magma the contribution to the total heat flux was 45 max from a magma chamber 35 min from shallow intrusions and 20 from eruptions this implies that magma at the roof of a chamber solidified and cooled at the rate of 1 2 1 6 107 m a 1 or about 1 km over the last 69 years heat release at grimsvotn was probably more intense in the 19th century when volcanic eruptions were more frequent

borehole erosion test abstractsoil erosion is a major problem in civil engineering it is involved in bridge scour meander migration levee overtopping internal erosion of earth dams surface erosion of embankments a

ice volcano interaction of the 1996 gjalp subglacial eruption vatnajokull iceland volcanic eruptions under glaciers can cause dangerous floods and lahars1 2 3 and create hyaloclastite fragmented glassy rock mountains4 5 6 7 8 but processes such as the rate of heat transfer between ice and magma edifice formation and the response of the surrounding glacier are poorly understood because of the lack of data here we present observations from the fissure eruption at vatnajokull ice cap iceland in october 1996 in the 13 days of the eruption 3 km3 of ice were melted and the erupted magma fragmented into glass forming a hyaloclastite ridge 6 7 km long and 200 300 m high under 500 750 m of ice meltwater of temperatures of 15 20 c flowed along a narrow channel at the glacier bed into the grimsvotn subglacial lake for five weeks before draining in a sudden flood or jokulhlaup subsidence and crevassing of the ice cap occurred over the eruptive fissure and the meltwater path whereas elsewhere the glacier surface remained intact suggesting that subglacial eruptions do not trigger widespread basal sliding in warm based glaciers

imaging the crustal structure throughout the east anatolian fault zone turkey by local earthquake tomography this paper presents new models of the seismic velocity structure of eastern anatolia turkey we applied a local earthquake tomography method to arrival time data produced by local and regional events in eastern anatolia to understand the three dimensional seismic velocity and vp vs models and their correlation with the geological evolution and tectonic processes in the study area the data are obtained from 78 broadband seismic stations owned by the earthquake department of the disaster and emergency management presidency for the period between 2008 and 2017 seven depth cross sections are taken along various segments of the east anatolian fault zone travel times of 53 099 phase readings 29 122 p phase and 23 977 s phase picks from 4249 high quality earthquake recordings are analysed to develop 3 d vp lithological and vp vs petrological models of the study area the resulting p wave velocities describe intrusive magmatic bodies sediment thickness and the structure of the basin the vp vs structures aid to limit the position of the faults areas of weakness and gas or liquid saturated units with regions of high pore pressure four main seismic crustal layers down to 40 km are determined the upper crust 0 8 km has vp 4 6 km s whereas in the middle crust 9 20 km a vp perturbation between 4 6 and 5 8 km s is observed in the lower crust 20 35 km vp changes from 5 9 to 7 3 km s and in the upper mantle layer below 36 km vp exceeds 7 4 km s in all cases seismic velocities are well resolved in the first 40 km tomograms are compatible with the geological characteristics of the region dominant high p velocity values are observed beneath the collision zone conrad discontinuity is detectable at 20 km depth while moho depth is observed to vary between 30 and 40 km in the study area

stochastic flow analysis for predicting river scour of cohesive soils damage to bridge crossings during flood events endangers the lives of the traveling public and causes costly disruptions to traffic flow the most common causes of bridge collapse are scouring of the streambed and banks and erosion of highway embankments this study couples a synthetic river flow simulation technique with a scour model for cohesive soils and determines the expected scour depth for a given lifetime of the bridge a fractionally differenced autoregressive integrated moving average model generates synthetic streamflow sequences of the same length as the expected lifetime of the bridge the scour model predicts the progression of scour depth through time in a multilayered soil the model is used to determine the scour depth associated with different replicates of the synthetic flow sequences of the same length as the lifetime of the bridge the probability distribution of scour depth is estimated by repeating this simulation procedure over a number of independent realizations of streamflow series for a given life of the bridge this approach provides a framework for the probabilistic design and risk analysis of bridge foundations subjected to scour

erosion study of new orleans levee materials subjected to plunging water during hurricane katrina overtopping water caused erosion and subsequent failure of several sections of i type flood walls in new orleans erosion stemmed from the kinetic energy of water falling from the top of the flood wall unlike the typical surface erosion caused by shear flow this study evaluated the effects of important parameters of levee soils fines content degree of compaction doc clay mineralogy and water content in relation to the erosion behavior of new orleans levees subjected to the plunging water in general test results showed that a higher fines content contributed to greater erosion resistance the trend became unclear when fines content exceeded 20 25 a higher degree of compaction did not necessarily contribute to greater erosion resistance underwater soaked soils showed much less erosion resistance than nonsoaked soils soils containing expansive clay minerals showed less erosion resistance than soils containing nonexpansive clay minerals

measurements of sediment erosion and transport with the adjustable shear stress erosion and transport flume soil and sediments play an important role in water management and water quality issues such as water turbidity associated contaminants reservoir sedimentation undesirable erosion and scour and aquatic habitat are all linked to sediment properties and behaviors in situ analysis is necessary to develop an understanding of the erosion and transport of sediments sandia national laboratories has recently patented the adjustable shear stress erosion and transport asset flume that quantifies in situ erosion of a sediment core with depth while affording simultaneous examination of transport modes bedload versus suspended load of the eroded material core erosion rates and ratios of bedload to suspended load transport of quartz sediments were studied with the asset flume the erosion and transport of a fine grained natural cohesive sediment were also observed experiments using quartz sands revealed that the ratio of suspended load to bedload sediment transport is a function of grain diameter and shear

breaching parameters for earth and rockfill dams dam risk analysis is at the heart of dam failure prevention and mitigation in order to assess dam risk it is essential to conduct a quantitative analysis of the process of a dam breach which can be described by such parameters as breach geometry breaching duration and peak outflow rate the main objective of this paper is to develop robust empirical formulas with physical meaning for predicting dam breaching parameters based on past dam failure data a database of 182 earth and rockfill dam failure cases has been compiled among these cases nearly one half are for large dams higher than 15 m a multiparameter nonlinear regression model is recommended to develop empirical relationships between five breaching parameters breach depth breach top width average breach width peak outflow rate and failure time and five selected dam and reservoir control variables dam height reservoir shape coefficient dam type failure mode and dam erodibility the relative importance of each control variable is evaluated the dam erodibility is found to be the most important factor influencing all five breaching parameters the reservoir shape coefficient and the failure mode also play an important role in the prediction models two case studies are presented to show the application of the empirical models developed in this paper

erosional and mechanical strengths of deposited cohesive sediments erosion tests were run on soft cohesive sediment beds freshly deposited from a concentrated slurry in a large rotating annular flume a total of seven tests were carried out with the bed age varying between 1 8 days and 18 9 days a surface type erosion was observed for the applied shear stress range 0 1 1 pa following the increase in the water flow the erosion rate increases quickly to a peak value and then drops off to approximately zero the eroded depth was less than 8 mm for all beds but the resistance to erosion at a given depth and for a given bed structure increased with increasing bed age this phenomenon was attributed to thixotropy the erosional strength of a given sediment layer is found to be one order of magnitude lower than its undrained and drained mechanical shear strengths measured with innovative testing methods hypotheses are given to explain that difference however at constant density and soil water chemistry the erosional and mechanical strengths seem to be affected by the same factors such as bed age structure and temperature

tomographic pn velocity and anisotropy structure beneath the anatolian plateau eastern turkey and the surrounding regions an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017391 shtml http atlas geo cornell edu turkey publications al lazki et al 2003 htm

curie point depth investigation of central anatolia turkey the residual aeromagnetic total field intensity anomalies in central anatolia were calculated from the regional aeromagnetic anomalies surveyed by the mineral research and exploration mta of turkey the residual aeromagnetic data were analyzed to produce curie point estimates by the method of okubo et al 1985 the curie point depth of central anatolia varies from 7 9 km and 22 6 km the shallowest curie point depths were observed around the cappadocia and erciyes volcanic complexes in central anatolia a good correlation was deduced between the curie point depths and the heat flow data measured previously which is most certainly important for the geothermal resources of the region the shallow curie point depths also correlate well with the hot spring locations in central anatolia

a general analytical solution for the evolution of cliffs accounting for strength degradation seismic action formation of tension cracks and seepage abstract the evolution of natural slopes over time is ruled by several concurrent physical phenomena namely the strength of its component geomaterials and their weakening over time due to weathering processes the occurrence of seismic events seepage and the formation of tension cracks the paper presents analytical solutions obtained considering a succession of discrete failure events landslides progressively altering the slope morphology over time the model derived in the framework of limit analysis assuming plane strain conditions provides a tool for the assessment of whether manufacts and or infrastructures located on a slope subject to various natural degradation phenomena will be affected by the occurrence of failures unlike current empirical and semi empirical models of slope evolution the analytical solution that is here presented is derived by applying principles of soil and rock mechanics therefore it is of general validity so that no ad hoc calibration against past observations of the evolving slope is needed this analytical technique only requires knowledge of the geotechnical parameters characterising the geomaterials comprising the slope of interest namely angle of shearing resistance cohesion c tensile strength unit weight together with knowledge of the relevant seepage scenarios strength degradation processes and seismic events likely to occur results show that that earthquake loading and seepage can substantially decrease slope stability increase the volume of material sliding away during each landslide event and alter the evolution of the slope over time while tensile strength exhibits a less strong influence especially as strength degradation progresses dimensionless ready to use charts are provided for the benefit of practitioners

curie point depths of the island of kyushu and surrounding areas japan as part of a comprehensive nationwide evaluation of geothermal resources for japan the first of the curie point depth maps covering the island of kyushu has been prepared the map was created by inverting gridded regional aeromagnetic data two satisfactory algorithms were developed to invert the gridded data based upon a distribution of point dipoles the first algorithm estimates x0 y0 and z0 the coordinates of the centroid of the distribution by computing a least squares fit to the radial frequency of the fourier transform the second algorithm estimates centroid depth only by computing a least squares fit to the squared amplitude of the frequency estimates the average depth to the top zt of the collection of point dipoles was estimated by a variation of the second algorithm the depth to the bottom of the dipoles inferred curie point depth is zb 2z0 zt the depth estimates are hand contoured to produce the final map the curie point depth map is then compared to regional geology and heat

mantle heat flow and geotherms for the main geologic domains in morocco thermal and deep seismic soundings data are used to study the dependence between the compressional pn velocity and the surface heat flow or the temperature at the moho discontinuity in morocco this correlation indicates a significant decrease in pn velocity where high heat flow and moho temperature are observed this result is consistent with respect to other regions of the world crustal heat generation models and geotherms are constructed for the major moroccan geological domains extending from the precambrian units in the south to the alpine units in the north the crustal contribution in surface heat flow is on average 35 mwm 2 with high values of 41 42 mwm 2 in the western and eastern meseta where hercynian granite intrusions could enrich the crust in radioactive heat sources high mantle heat flow values are obtained beneath the alboran neogene basin 62 mwm 2 the rif 47 mwm 2 the middle atlas 41 mwm 2 and the south atlantic margin 40 mwm 2 where the crust is thinned by an extensional tectonic regime despite their similar formation context the intra continental belts of the middle and the high atlas show different geothermal field components a lithospheric heating process in the middle atlas could be the result of a plio quaternary basaltic volcanism finally the precambrian basement of the anti atlas like all the west african shield is a stable domain showing the lowest subsurface temperatures

erosivity of natural intact structured clay evaluation previous studies on erodibility of cohesive soil are briefly reviewed and it is concluded that experimental observations have been mainly concerned with remolded and reconsolidated or weathered cla

new evidence and model on the evolution of the southeast anatolian orogen this paper describes the orogenic evolution of the southeast anatolian orogenic belt based mostly on new geologic data collected from its constituent tectonic units in the course of new mapping programs of the past decade the southeast anatolian orogenic segment of the alpides may be divided into three approximately east west trending zones from south to north they are the arabian platform followed by a zone of imbrication and then a zone of nappes the arabian platform includes a mostly marine sedimentary succession deposited from early cambrian to middle miocene time the zone of imbrication is a narrow belt sandwiched between the arabian platform and the zone of nappes it consists of imbricated thrust slices emplaced onto a late cretaceous to early miocene sequence the zone of nappes is the highest tectonic unit consisting of two stacks of nappes simply designated the lower and upper nappes the lower nappe is represented by the slices of a polyphase metamorpbic ophiolitic assemblage and the maden group the upper nappe rests on the lower nappe and is represented by the bitlis and poturge metamorphic massifs southeastern anatolia underwent two major episodes of alpide deformation the first occurred during the late cretaceous period when ophiolite was emplaced on the arabian platform this event was not the consequence of a continental collision the ophiolite obduction onto the arabian platform was followed by a regionwide extension and a new marine transgression over the platform immediately after the ophiolite obduction the second episode of deformation occurred during middle eocene miocene time in two distinct stages as a result of the progressive elimination and complete closure of the ocean s which led to the collision between the zone of nappes located to the north being a part of eurasia and the arabian plate the maden marginal basin formed north of the subduction zone that eliminated the ocean between eurasia and arabia along the southern margin of the taurus belt and abutted the arabian plate much later during the final collision the second episode of deformation formed the present orogenic segment leading to the amalgamation of different tectonic units these amalgamated nappes collided with the arabian plate and welded onto it at the latest stage of the orogenic evolution during the miocene epoch

stable width and depth of gravel bed rivers with cohesive banks an analytical model is developed to determine the influence of the bank stability on the stable width and depth of alluvial gravel bed rivers with cohesive banks the formulation of the model is based on the assumption that the stable width corresponds with an optimum condition that is equivalent to the maximum bed load transporting capacity the optimum condition develops when the channel banks are at their limiting stability with respect to either mass failure or fluvial erosion two basic channel types are identified bank height and bank shear constrained mass failure stability is estimated using a simple total stress approach a method for estimating the critical bank shear stress based on model calibration is proposed analysis of field data indicates that the effect of the bank vegetation on bank stability can be expressed in terms of the critical bank shear stress the average critical bank shear stress value calculated for riverbanks covered by vegetation with well developed root networks was fo

cohesive material erosion by unidirectional current the initiation of motion of consolidated cohesive sediments under a unidirectional flow of clear water was studied experiments were performed in a flume tunnel capable of providing a bed shear stress up to 26 pa and a velocity of 3 5 m s 3 mm above the bed samples were prepared in a specially designed press using a carefully controlled consolidation procedure critical shear stress and velocity were found to increase with compressive strength vane shear strength plasticity index clay content and consolidation pressure

lithospheric velocity structure of the anatolian plateau caucasus caspian region 1 the anatolian plateau caucasus caspian region is an area of complex lithospheric structure accompanied by large variations in seismic wave velocities despite the complexity of the region little is known about the detailed lithospheric structure using data from 31 new permanent broadband seismic stations along with results from a previous 29 temporary seismic stations and 3 existing global seismic stations in the region a 3 d velocity model is developed using joint inversion of teleseismic receiver functions and surface waves both group and phase dispersion curves love and rayleigh were derived from regional and teleseismic events additional rayleigh wave group dispersion curves were determined using ambient noise correlation receiver functions were calculated using p arrivals from 789 teleseismic 30 90 earthquakes the stacked receiver functions and surface wave dispersion curves were jointly inverted to yield the absolute shear wave velocity to a depth of 100 km at each station the depths of major discontinuities sediment basement crust mantle and lithosphere asthenosphere were inferred from the velocity depth profiles at the location of each station distinct spatial variations in crustal and upper mantle shear velocities were observed the kura basin showed slow 2 7 2 9 km s upper crustal 0 11 km velocities but elevated 3 8 3 9 km s velocities in the lower crust the anatolian plateau varied from 3 1 3 2 in the upper crust to 3 5 3 7 in the lower crust while velocities in the arabian plate south of the bitlis suture were slightly faster upper crust between 3 3 and 3 4 km s and lower crust between 3 8 and 3 9 km s the depth of the moho which was estimated from the shear velocity profiles was 35 km in the arabian plate and increased northward to 54 km at the southern edge of the greater caucasus moho depths in the kura and at the edge of the caspian showed more spatial variability but ranged between 35 and 45 km upper mantle velocities were slow under the anatolian plateau but increased to the south under the arabian plate and to the east 4 3 4 4 km s under the kura basin and greater caucasus the areas of slow mantle coincided with the locations of holocene volcanoes differences between rayleigh and love dispersions at long wavelengths reveal a pronounced variation in anisotropy between the anatolian plateau and the kura basin

sn attenuation in the anatolian and iranian plateau and surrounding regions an edited version of this paper was published in geophysical research letters by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl018020 shtml http atlas geo cornell edu turkey publications gok et al 2003 htm

determination of the crustal and thermal structure of the erzurum horasan pasinler basins eastern turkiye using gravity and magnetic data the erzurum horasan pasinler basin which surrounds miocene rocks is oriented approximately e w and is located in eastern anatolia turkiye east anatolia where ophiolitic and young volcanic rocks are widespread is situated in the alpine himalayan fold thrust fault belt the nw se trending north anatolian transform fault zone and the ne sw trending east anatolian transform fault zone formed by the compressional regime of east anatolia control the main tectonics of the study region while the moho and conrad depths of the study region are 43 0 and 20 9 km respectively the average sedimentary thickness has been determined to be 5 2 km by using the power spectrum method on the other hand it is found that the depth of the moho in the region varies from 41 0 to 44 5 km and the depth of the conrad discontinuity varies between 22 and 26 km as computed using empirical equations the basement of the sedimentary layer is calculated to be 6 km by using inversion results applied to the residual gravity data the curie point depth and average heat flow value in this region are calculated as 18 0 km and 89 1 m wm 2 respectively geotherm calculations reveal that the moho temperature is 1 028 0 c based on the crustal model the high heat flow values obtained are attributed to tectonic activities and melting of the lithospheric mantle caused by upwelling of the asthenosphere

the crustal structure of the east anatolian plateau turkey from receiver functions an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl018192 shtml http atlas geo cornell edu turkey publications zor et al 2003 htm

infrared monitoring of volcanoes by satellite sensors on future satellite platforms will be used routinely for volcano monitoring with infrared channels offering the potential to detect and measure temperatures of features such as lava bodies and fumarole fields this is possible even though the surface temperature distributions associated with such phenomena are typically inhomogeneous at the pixel scale so long as simplifying assumptions can be made to test the applicability of the technique we have carried out field studies of a range of volcanic thermal manifestations using portable infrared thermometers rock surface temperatures around fumarolic vents exhibit greater stability with time than those associated with actively degassing lava bodies but in both cases volcanogenic fumes can significantly attenuate the emitted infrared radiation the scale of the temporal variability at a given wavelength dictates the quantitative value of isolated satellite 9snapshots9 if more spectral channels in the infrared were available on remote sensing platforms then more components of the surface temperature distribution could be extracted from the data imaging spectrometry offers the greatest flexibility although data processing including correction for atmospheric effects would present difficulties

east anatolian high plateau as a mantle supported north south shortened domal structure an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017858 shtml http atlas geo cornell edu turkey publications sengor et al 2003 htm

geothermal structure in a seismoactive region of central india the geothermal structure beneath a seismoactive region of central india has been determined by using two independent geophysical parameters i e p n velocity and curie point depth which are temperature dependent p n velocity has been determined by reanalyzing deep seismic sounding dss records obtained for this region surface heat flow has been computed using the p n velocity data from this region and found to be 55 5 mw m 2 curie point depths have been derived from the magnetic satellite data in this region and reveal an identical value of heat flow of around 56 4 mw m 2 we estimated temperatures of 600 700 c at a moho depth of 39 km by using surface heat flow ranging from 50 to 60 mw m 2 and a simple 1 d geothermal model the present study suggests the presence of a brittle ductile transition high strength zone ranging in depth from 20 to 35 km where the temperatures range from 350 to 550 c we also suggest that the nucleation of earthquakes in this region took place in a relatively high strength zone this is supported by the fact that the focal depths of all the recent earthquakes from 1978 to 2000 of magnitude 3 5 lie in this zone of high strength

investigation of crustal thickness in eastern anatolia using gravity magnetic and topographic data the tectonic regime of eastern anatolia is determined by the arabia eurasia continent continent collision several dynamic models have been proposed to characterize the collision zone and its geodynamic structure in this study change in crustal thickness has been investigated using gravity magnetic and topographic data of the region in the first stage two dimensional low pass filter and upward analytical continuation techniques were applied to the bouguer gravity data of the region to investigate the behavior of the regional gravity anomalies next the moving window power spectrum method was used and changes in the probable structural depths from 38 to 52 km were determined the changes in crustal thickness where free air gravity and magnetic data have inversely correlated and the type of the anomaly resources were investigated applying the euler deconvolution method to bouguer gravity data the obtained depth values are consistent with the results obtained using the power spectrum method it was determined that the types of anomaly resources are different in the west and east of the 40 e longitude finally using the obtained findings from this study and seismic velocity models proposed for this region by previous studies a probable two dimensional crust model was constituted

parabolic density function in sedimentary basin modelling for modelling sedimentary basins of large thickness from their gravity anomalies the concept of parabolic density function which explains the variation of true density contrast of the sediments with depth in such basins is introduced inbott s 1960 procedure the analytical expression the gravity anomaly of a two dimensional vertical prism with parabolic density contrast needed to estimate the gravity effect of the basin in modelling procedure is derived in a closed form two profiles of gravity anomalies one across san jacinto graben california and the other across tucson basin arizona where the density of sediments is found to vary with depth are interpreted

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

an improved rotating cylinder technique for quantitative measurements of the scour resistance of clays the methods developed to predict the action of eroding fluid on cohesive soils lead to contradictory predictions most of them are questionable since they ignore the physicochemical parameters that seem to control the erosion process in order to study the scour resistance of intact or remolded cohesive soils a rotating cylinder technique allowing for the control of essential parameters was recently improved by the authors intact or remolded samples can be used the water quality is controlled in order to respect the in situ physicochemical conditions the shear stress transmitted by water to the clay surface is directly and accurately derived the dry weight of eroded material per unit time and unit area for given conditions is also directly and adequately measured the influence of water quality or of any treatment of the clay may be quantitatively analyzed

determination of tectonic and crustal structure of the eastern pontide orogenic belt ne turkey using gravity and magnetic data the eastern pontide orogenic belt is one of the most complex geodynamic settings within the alpine belt subduction polarity which is responsible for the formation of the eastern pontide magmatic arc is still under debate because of limited geological geophysical and geochemical data this orogenic belt is mainly divided into three subzones depending on lithological characteristics and facies changes as in northern southern and axial zones from north to south these zones are separated from each other by near vertical faults that display the block faulting tectonic style of this belt in this study the tectonic and crustal structure of the eastern pontides which as yet have not been prospected by using geophysical data has been investigated with potential field data the horizontal gradient map obtained from gravity data shows a number of steep and gentle lineaments it seems that these lineaments e w ne and nw trending correspond to major structural zones of continental crust additionally the moho depth and curie point depth variation maps of the eastern pontide orogenic belt have been computed with the power spectral method of the radial wavenumber carried out by using the fast fourier transform method as a result of this method we estimated that the depths of the moho and curie point varied between 29 0 1 2 47 2 1 9 km and 14 3 0 7 27 9 1 4 km respectively our findings indicate that the moho depth generally increases from north to south in the region however the curie point depth level within the crust has an undulating surface not a horizontal one

the 1969 subglacial eruption on deception island antarctica events and processes during an eruption beneath a thin glacier and implications for volcanic hazards a short lived eruption of basaltic andesite to andesite on deception island in 1969 occurred from a series of fissures underneath a glacier the glacier was thin c 100 m and the eruption created a large and sudden discharge of meltwater that overflowed the glacier severely damaging buildings on the island the eruption was unusually well documented and it illustrates several features of subglacial eruptions that are only poorly known and not well understood in particular overflowing meltwater is contrary to predictions based on existing simple hydrological models for eruptions beneath thin glaciers the eruption is analysed in this paper and used as a model for the fluid dynamics and thermodynamics of eruptions beneath a thin glacier mainly composed of impermeable ice it is suggested that in eruptions of relatively fluid magmas with a low magma rise rate volatiles and magma are able to decouple and subglacial melting is strongly influenced by the superheated magmatic and hydrothermal gases mainly steam thus melting is much faster than that due solely to coupled conductive magma and convective meltwater heat transfer the influence of gasdriven melting also has an important effect on the shape of the meltwater cavity and may be at least partly responsible for the cylindrical ice chimneys developed above vents on deception island the results of the study are important for reconstructing the shapes of englacial cavities melted above a vent they also highlight the importance of glacier structure and densification rather than simply glacier thickness in determining the hydraulic evolution of an eruption even eruptions beneath thin glaciers can generate significant meltwater floods

measurements of erosion of undisturbed bottom sediments with depth a unique flume that measures the erosion of sediments at high shear stresses and with sediment depth has been designed constructed and used experiments in this flume sedflume can be done either with reconstructed sediments or with relatively undisturbed sediments from the field with either kind of sediment two different types of experiments can be conducted the first type determines the critical stress for erosion of the sediment as a function of depth while the second type determines the erosion rate of the sediment as a function of both shear stress and depth measurements of the erosion rates of sediments from the trenton channel of the detroit river in michigan and the lower fox river in wisconsin were made by use of sedflume at sediment depths up to 2 m representative results of these measurements are presented here these results demonstrate the capabilities of sedflume and also illustrate the large differences in erosion rates at different sites and the large variations in erosion rates with depth and as a function of shear stress

geochemical and sr nd pb isotopic compositions of the eocene dolek and saricicek plutons eastern turkey implications for magma interaction in the genesis of high k calc alkaline granitoids in a post collision extensional setting abstract the major and trace elements and sr nd pb isotopes of the host rocks and the mafic microgranular enclaves mme gathered from the dolek and saricicek plutons eastern turkey were studied to understand the underlying petrogenesis and geodynamic setting the plutons were emplaced at 43 ma at shallow depths 5 to 9 km as estimated from al in hornblende geobarometry the host rocks consist of a variety of rock types ranging from diorite to granite sio 2 56 98 72 67 wt mg 36 8 50 0 populated by mmes of gabbroic diorite to monzodiorite in composition sio 2 53 21 60 94 wt mg 44 4 53 5 all the rocks show a high k calc alkaline differentiation trend chondrite normalized ree patterns are moderately fractionated and relatively flat la yb n 5 11 to 8 51 they display small negative eu anomalies eu eu 0 62 to 0 88 with enrichment of lile and depletion of hfse initial nd sr isotopic compositions for the host rocks are e nd 43 ma 0 6 to 0 8 and mostly i sr 0 70482 0 70548 the nd model ages t dm vary from 0 84 to 0 99 ga the pb isotopic ratios are 206 pb 204 pb 18 60 18 65 207 pb 204 pb 15 61 15 66 and 208 pb 204 pb 38 69 38 85 compared with the host rocks the mmes are relatively homogeneous in isotopic composition with i sr ranging from 0 70485 to 0 70517 e nd 43 ma 0 1 to 0 8 and with pb isotopic ratios of 206 pb 204 pb 18 58 18 64 207 pb 204 pb 15 60 15 66 and 208 pb 204 pb 38 64 38 77 the mmes have t dm ranging from 0 86 to 1 36 ga the geochemical and isotopic similarities between the mmes and their host rocks indicate that the enclaves are of mixed origin and are most probably formed by the interaction between the lower crust and mantle derived magmas all the geochemical data in conjunction with the geodynamic evidence suggest that a basic magma derived from an enriched subcontinental lithospheric mantle probably triggered by the upwelling of the asthenophere and interacted with a crustal melt that originated from the dehydration melting of the mafic lower crust at deep crustal levels modeling based on the sr nd isotope data indicates that 77 83 of the subcontinental lithospheric mantle involved in the genesis consequently the interaction process played an important role in the genesis of the hybrid granitoid bodies which subsequently underwent a fractional crystallization process along with minor amounts of crustal assimilation en route to the upper crustal levels generating a wide variety of rock types ranging from diorite to granite in an extensional regime

measurement of fluctuating pressures on coarse bed material bed protections are usually characterized by low mobility transport conditions and nonequilibrium turbulence profiles as the present knowledge of the influence of turbulence on stability of cover layer units is minimal an in depth investigation was undertaken regarding the influence of turbulence on the stability of rough granular beds detailed measurements of fluctuating pressures on a bed element are used to evaluate certain concepts that are often used in modeling the entrainment of bed material from hydraulically rough beds three pressure transducers are placed in a cube that is part of a rough granular bed under open channel flow and velocities are measured using laser doppler velocimetry the measurements show that the magnitude of the fluctuating pressure at a certain point of the cube is a function of the exposure relative to the stones upstream of the cube a quadrant analysis reveals that the drag force is not only directly dependent on the horizontal near bed velocity but on the vertical velocity as well further the effect of small scale eddies shedding from the stone during large scale increases of longitudinal velocity is shown the fact that large scale velocity fluctuations create a large part of the pressure or force variance indicates that downstream of a roughness transition these fluctuations have to be taken into account in order to evaluate the stability of the bed

crustal and upper mantle structure across the dead sea rift and israel from teleseismic p wave tomography and gravity data abstract new findings of the structure of the crust and the upper mantle across the dead sea rift and israel were obtained by applying p and pkp wave relative travel time residuals inversion of 612 teleseisms recorded by the seismic networks in israel and jordan independently of the relative teleseismic travel time residuals the bouguer gravity anomalies were used as an additional aid to examine the structure of the crust and upper mantle an examination of the teleseismic travel time residuals in israel suggests the existence of two prominent provinces of distinct crustal structure the northward increase of the teleseismic travel time residuals is in good agreement with a gradual thickening of the sedimentary sequence and a simultaneous thinning of the crust examination of the inverted velocity anomalies indicates that the upper and lower crusts are sub divided into a number of structures we identify several velocity anomalies that are associated with prominent geological structures the southern dead sea basin is characterized with the largest decrease of velocity in both upper and lower crustal layers due to the infilling of light material relative to the surrounding material the velocity anomaly in the carmel structure is probably associated with variations in the upper part of the upper mantle examination of a cross section that traverses the dead sea transform supports the existence of lighter mass density material on the eastern side relative to that on the western side

the 1996 eruption at gjalp vatnajokull ice cap iceland efficiency of heat transfer ice deformation and subglacial water pressure the 13 day long gjlp eruption within the vatnajkull ice cap in october 1996 provided important data on ice volcano interaction in a thick temperate glacier the eruption produced 0 8 km 3 of mainly volcanic glass with a basaltic icelandite composition equivalent to 0 45 km 3 of magma ice thickness above the 6 km long volcanic fissure was initially 550 750 m the eruption was mainly subglacial forming a 150 500 m high ridge only 2 4 of the volcanic material was erupted subaerially monitoring of the formation of ice cauldrons above the vents provided data on ice melting heat flux and indirectly on eruption rate the heat flux was 5 6 10 5 wm 2 in the first 4 days this high heat flux can only be explained by fragmentation of magma into volcanic glass the pattern of ice melting during and after the eruption indicates that the efficiency of instantaneous heat exchange between magma and ice at the eruption site was 50 60 if this is characteristic for magma frag mentation in subglacial eruptions volcanic material and meltwater will in most cases take up more space than the ice melted in the eruption water accumulation would therefore cause buildup of basal water pressure and lead to rapid release of the meltwater continuous drainage of meltwater is therefore the most likely scenario in subglacial eruptions under temperate glaciers deforma tion and fracturing of ice played a significant role in the eruption and modified the subglacial water pressure it is found that water pressure at a vent under a subsiding cauldron is substantially less than it would be during static loading by the overlying ice since the load is partly compensated for by shear forces in the rapidly deforming ice in addition to intensive crevassing due to subsidence at gjlp a long and straight crevasse formed over the southernmost part of the volcanic fissure on the first day of the eruption it is suggested that the feeder dyke may have overshot the bedrock ice interface caused high deformation rates and fractured the ice up to the surface the crevasse later modified the flow of meltwater explaining surface flow of water past the highest part of the edifice the dominance of magma fragmentation in the gjlp eruption suggests that initial ice thickness greater than 600 700 m is required if effusive eruption of pillow lava is to be the main style of activity at least in similar eruptions of high initial magma discharge

quantitative measurement of the scour resistance of natural solid clays the erosion of clayey soils is a complex phenomenon that includes various types of erosive actions a tentative classification of erosion processes is proposed this paper concentrates on the scour resistance of solid clays available prediction methods are reviewed generally they propose relationships between physical or mechanical parameters and the critical hydraulic shear stress tau sub c that defines a boundary between no erosion and erosion it became apparent that the physicochemical parameters of both the clay and eroding water control the erosion process however subsequent studies on these parameters have yet to yield reliable predictions of natural clay erodibility from indirect measurements an erosion testing program was therefore performed on three quebec clays with the improved rotating cylinder technique in this test intact or remolded samples can be tested physicochemical parameters can be controlled and the hydraulic shear stress tau and the erosion rate e can be adequately determined a relatively complete and accurate graph of e versus tau including e values for tau values lower than critical can be established previous and present research underline the need to exert a strict control of all clay and water parameters including that of sample preparation in order to adequately simulate a field problem

one dimensional thermal modeling of the eastern pontides orogenic belt ne turkey the eastern pontides orogenic belt is one of the most complex geodynamic settings in the alpine himalayan belt due to the lack of systematical geological and geophysical data in this study 1d crustal structure and p wave velocity distribution obtained from gravity modeling and seismological data in the area has been used for the development of the thermal model of the eastern pontides orogenic belt the computed temperature depth profiles suggest a temperature of 590 60 c at a moho depth of 35 km indicates the presence of a brittle ductile transition zone this temperature value might be related to water in the subducted crust of the tethys oceanic lithosphere the curie temperature depth value of 29 km which may correspond to the crustal magma chambers is found 5 7 km below the moho depth surface heat flow density values vary from 66 5 and 104 7 mw m 2 high mantle heat flow density value of 48 mw m 2 is obtained for the area should be related to melting of the lithospheric mantle caused by upwelling of asthenosphere

curie point depth map of turkey summary a curie point isotherm map of the whole of turkey has been prepared from aeromagnetic data by means of a spectral analysis technique the most characteristic signature of this map is that the shallow depths generally correlated with the young volcanic rocks and the thinned crustal thicknesses in the west reveal geothermal fields and several hot springs the orogenic pontide belt of the black sea region in the north the western taurus belt in the south and some high plateaus in eastern turkey show that the deepest curie isotherm depths range between 20 and 29 km depth contour lines elongating in an almost e w direction are due to the overlapping percentage of adjacent data blocks of 50 per cent in the e w direction and to magnetic anomalies trending in the e w direction curie isotherm depths are in the range 6 to 10 km in the aegean region and are characterized by e w and ne sw trending graben structures as expected since the region has crustal thinning and many hot springs and geothermal fields these imply the existence of shallow heat sources that could be utilized for electricity heating of towns and cities greenhouse and health purposes

multiflood and multilayer method for scour rate prediction at bridge piers the sricos method was proposed in 1999 to predict the scour depth versus time curve at a cylindrical bridge pier for a constant velocity flow a uniform soil and a deep water condition in this article the method is extended to include a random velocity time history and a multilayer soil stratigraphy it is called the extended sricos or e sricos the algorithms to accumulate the effects of different velocities and to sequence through a series of soil layers are described the procedure followed by the computer program to step into time is outlined a simplified version of e sricos called s sricos is also presented calculations for the s sricos method can easily be done by hand eight bridges in texas are used as case histories to compare predictions by the two new methods e sricos and s sricos with measurements at the bridge sites

genesis of collision volcanism in eastern anatolia turkey late cenozoic volcanism in eastern anatolia extends in a broad sw ne trending belt across the arabia eurasia collision zone from the arabian foreland basin in the southwest and to the kars plateau and lesser caucasus in the northeast foreland volcanism is dominated by basaltic shield and fissure eruptions of transitional tholeiitic alkaline composition volcanism on the thickened crust north of the bitlis thrust zone varies from the mildly alkaline volcano nemrut and older mus volcanics in the south through the transitional calc alkaline alkaline volcanoes bingol and suphan and the alkaline volcano tendurek to the calc alkaline volcano ararat and older kars plateau volcanics in the north isotope sr nd and trace element systematics indicate that the lavas from the foreland were derived from the mantle lithosphere of the arabian continent which had been enriched by small volumes of asthenospheric melts over a period of time and that lavas from the alkaline volcanic area around mus and the volcanoes nemrut and tendurek north of the bitlis thrust zone were derived from a lithospheric source of similar composition either from the same underthrust arabian continent or from the bitlis massif microcontinent by contrast the transitional lavas from bingol and suphan and the calc alkaline lavas from ararat and kars were derived from lithosphere carrying a distinct subduction signature inherited from pre collision subduction events positive correlations between 87sr 86sr and sio2 and rb nb and sio2 in the alkaline and transitional lavas suggest that combined assimilation and fractional crystallization was an important process within at least part of the thickened crust of the collision zone trace element covariation diagrams such as y rb indicate the importance of hornblende crystallization at depth and orthopyroxene at shallow levels within the calc alkaline provinces in contrast to the consistently anhydrous crystallization sequences of the alkaline lavas trace element diagrams based on the covariation of compatible and incompatible elements point to moderate low degrees of partial melting with residual clinopyroxene throughout and residual garnet in the foreland province consideration of mineral stabilities mantle solidi and geothermal gradients before and after collision suggest that lithospheric thickening should both increase the thickness of metasomatized lithosphere and depress the metasomatized zone to greater depths probably beneath the amphibole and dolomite breakdown curves perturbation of the thickened lithosphere by delamination of the thermal boundary layer perhaps coupled with local stretching associated with pull apart basins on strike slip fault systems is then sufficient to generate melt the composition of that melt being largely dependent on the enrichment history of the lithosphere in question in eastern anatolia volcanism appears to have started between about 8 and 6 ma ago some 5 ma after the start of rapid uplift of the east anatolian plateau

the hyaloclastite ridge formed in the subglacial 1996 eruption in gjalp vatnajokull iceland present day shape and future preservation

case histories in soil and rock erosion woodrow wilson bridge brazos river meander normandy cliffs and new orleans levees this lecture presents four case history examples of erosion processes because the topic of soil and rock erosion is relatively underdeveloped in geotechnical engineering an introduction precedes the case histories to describe some fundamental aspects of erosion erosion involves the soil or rock through its erodibility the water through its velocity and the geometry of the obstacle through its size and shape knowledge of these three components is needed for any erosion problem to be studied and solved a set of fundamental issues are addressed in the first part including an erodibility classification for soils and rocks an explanation of the stresses imposed by the water on the soil water or rock water interface and an explanation of how the geometry impacts the problem the woodrow wilson bridge case history outlines a new and less conservative method to compute the scour depth and gives examples of bridge scour calculations the brazos river meander case history outlines a new method to predict m

radiogenic heat production in the lithosphere of sulu ultrahigh pressure metamorphic belt abstract the chinese continental scientific drilling ccsd project is located at the sulu ultrahigh pressure metamorphic uhpm belt it offers a unique opportunity for studying the radiogenic heat production of both shallower and deeper rocks based on the concentrations of radiogenic elements u th and k on 349 samples from main hole of ccsd ccsd mh pilot holes and exposures we determined radiogenic heat productions of all major rock types in the sulu uhpm belt results show the mean values of orthogneiss and paragneiss are respectively 1 65 0 81 and 1 24 0 61 w m 3 due to different composition and grade of retrogressive metamorphism the eclogites display significant scatter in radiogenic heat production ranging from 0 01 to 2 85 w m 3 with a mean of 0 44 0 55 w m 3 the radiogenic heat production in ultramafic rocks also varies within a large range of 0 02 to 1 76 w m 3 and the average turns out to be 0 18 0 31 w m 3 based on the measurements and crustal petrologic model the vertical distribution model of heat production in sulu crust is established the resulting mean heat production 0 76 w m 3 contributes 24 mw m 2 to the surface heat flow 1 d thermal model indicates that the temperature at the moho reaches above 750 c and the thermal thickness of the lithosphere is 75 km in good agreement with the geophysical results the high teat flow 75 mw m 2 together with thin lithosphere presents strong support for the extension events during the late cretaceous and cenozoic

curie point depths based on spectrum analysis of aeromagnetic data west anatolian extensional province turkey the curie point depth map of western anatolia was constituted from spectral analysis of the aeromagnetic data the curie point depth values from 53 overlapping blocks 90 90 km in size have been estimated from the band pass filtered data the slope of the longest wavelength part of the radially averaged log power spectrum divided by the radial frequency produced the depth to the centroid z0 for the deepest crustal block the depth to the top zt was obtained by the slope of the second longest wavelength part of the spectrum from these depths the curie point depth was then calculated by using zb 2z0 zt the curie point depth estimates for western anatolia range between 8 2 and 19 9 km

understanding mass fluvial erosion along a bank profile using peep technology for quantifying retreat lengths and identifying event timing this study provides fundamental examination of mass fluvial erosion along a stream bank by identifying event timing quantifying retreat lengths and providing ranges of incipient shear stress for hydraulically driven erosion mass fluvial erosion is defined here as the detachment of thin soil layers or conglomerates from the bank face under higher hydraulic shear stresses relative to surface fluvial erosion or the entrainment of individual grains or aggregates under lower hydraulic shear stresses we explore the relationship between the two regimes in a representative us midwestern stream with semi cohesive bank soils namely clear creek ia photo electronic erosion pins peeps provide for the first time in situ measurements of mass fluvial erosion retreat lengths during a season the peeps were installed at identical locations where surface fluvial erosion measurements exist for identifying the transition point between the two regimes this transition is postulated to occur when the applied shear stress surpasses a second threshold namely the critical shear stress for mass fluvial erosion we hypothesize that the regimes are intricately related and surface fluvial erosion can facilitate mass fluvial erosion selective entrainment of unbound exposed mostly silt sized particles at low shear stresses over sand sized sediment can armor the bank surface limiting the removal of the underlying soil the armoring here is enhanced by cementation from the presence of optimal levels of sand and clay select studies show that fluvial erosion strength can increase several fold when appropriate amounts of sand and clay are mixed and cement together hence soil layers or conglomerates are entrained with higher flows the critical shear stress for mass fluvial erosion was found to be an order of magnitude higher than that of surface fluvial erosion and proceeded with higher approximately 2 4 times erodibility the results were well represented by a mechanistic detachment model that captures the two regimes copyright 2017 john wiley sons ltd

gravity inversion of basement relief using approximate equality constraints on depths we present a gravity interpretation method for estimating the relief of an arbitrary interface separating two homogeneous media the upper medium is discretized into rectangular juxtaposed prisms whose thicknesses represent the depths to the interface and are the parameters to be estimated from the gravity anomaly the density contrast of each prism is assumed to be constant and known to stabilize the inversion we introduce two kinds of constraints on the depths the first one requires proximity between the observed and computed depths at isolated points such as those obtained from boreholes absolute equality constraint the second one requires that groups of depths approximately follow an established linear relationship among the depths relative equality constraint both kinds of constraints are imposed in the least squares sense we illustrate the method performance by applying it to a synthetic anomaly produced by a simulated basement relief consisting of four narrow and adjacent structural lows

lithospheric structure of the arabian and eurasian collision zone in eastern turkey from s wave receiver functions summary crustal and upper mantle seismic discontinuities beneath eastern turkey are imaged using teleseismic s to p converted phases three crustal phases are observed the moho with depth ranging between 30 and 55 km indicating variable tectonic regimes within this continental collision zone an upper crustal discontinuity at approximately 10 km depth and various crustal low velocity zones possibly associated with recent quaternary volcanism imaging of the upper mantle is complicated by the 3 d geometry of the region in particular due to the bitlis zagros suture zone however several upper mantle s to p converted phase are identified as being the signature of the lithosphere asthenosphere boundary lab the inferred lab for the eastern anatolian accretionary complex indicates that eastern turkey has an anomalously thin between 60 and 80 km lithosphere which is consistent with an oceanic slab detachment model the observed lab phases for the arabian shield and iranian plateau indicate that lithospheric thickness for these stable regions is on the order of 100 to 125 km thick which is typical of continental margins

gravity inversion of basement relief constrained by the knowledge of depth at isolated points we present an interpretation method for the gravity anomaly of an arbitrary interface separating two homogeneous media it consists essentially of a downward continuation of the observed anomaly and the division of the continued anomaly by a scale factor involving the density contrast between the media the knowledge of the interface depth at isolated points is used to estimate the depth d1 of the shallowest point of the interface the density contrast between the two media and the coefficients c1 and c2 of a first order polynomial representing a linear trend to be removed from data the solutions are stabilized by introducing a damping parameter in the computation of the downward continued anomaly by the equivalent layer method different from other interface mapping methods using gravity data the proposed method 1 takes into account the presence of an undesirable linear trend in data 2 requires just intervals for both rather than the knowledge of its true value and coefficients c1 and c2

thermodynamics and fluid dynamics of effusive subglacial eruptions we consider the thermodynamic and fluid dynamic processes that occur during subglacial effusive eruptions subglacial eruptions typically generate catastrophic floods jokulhlaups due to melting of ice by lava and generation of a large water cavity we consider the heat transfer from basaltic and rhyolitic lava eruptions to the ice for typical ranges of magma discharge and geometry of subglacial lavas in iceland our analysis shows that the heat flux out of cooling lava is large enough to sustain vigorous natural convection in the surrounding meltwater in subglacial eruptions the temperature difference driving convection is in the range 10 100 c average temperature of the meltwater must exceed 4 c and is usually substantially greater we calculate melting rates of the walls of the ice cavity in the range 1 40 m day indicating that large subglacial lakes can form rapidly as observed in the 1918 eruption of katla and the 1996 eruption of gjalp fissure in vatnajokull the volume changes associated with subglacial eruptions can cause large pressure changes in the developing ice cavity these pressure changes can be much larger than those associated with variation of bedrock and glacier surface topography previous models of water cavity stability based on hydrostatic and equilibrium conditions may not be applicable to water cavities produced rapidly in volcanic eruptions energy released by cooling of basaltic lava at the temperature of 1200 c results in a volume deficiency due to volume difference between ice and water provided that heat exchange efficiency is greater than approximately 80 a negative pressure change inhibits escape of water allowing large cavities to build up rhyolitic eruptions and basaltic eruptions with less than approximately 80 heat exchange efficiency cause positive pressure changes promoting continual escape of meltwater the pressure changes in the water cavity can cause surface deformation of the ice laboratory experiments were carried out to investigate the development of a water cavity by melting ice from a finite source area at its base the results confirm that the water cavity develops by convective heat transfer