searching for ulf signatures of the cusp observations from search coil magnetometers and auroral imagers in svalbard 1 spacecraft traveling through the cusp at a variety of altitudes have consistently found the cusp to be filled with intense often irregular power in the upper ulf frequency range some ground based studies have observed narrowband waves in this same frequency range in the vicinity of the cusp foot point but it has not been possible with magnetometers alone to either confirm or deny a cusp source for these waves we report here on the first simultaneous collocated observations of a set of induction magnetometers installed at three near cusp sites on svalbard and an all sky auroral imager located at longyearbyen data during northern winters of 2006 2007 and 2007 2008 when the cusp foot point was in darkness showed occasional broadband noise when energetic particle precipitation occurred overhead but on most days no broadband ulf power was observed above the noise level near noon when only soft cusp precipitation or poleward moving auroral forms occurred overhead however on 3 days including 15 january 2007 several bursts of band limited pc 1 2 waves were observed in association with regions of intense soft precipitation that peaked near the poleward edge of the cusp their properties are consistent with an origin in the plasma mantle as observed in a recent satellite ground study by engebretson et al 2005 these observations confirm that even intense cusp precipitation is not effective in generating ion cyclotron waves that penetrate to the ground if it is embedded within the central regions of the cusp whereas regions of enhanced precipitation at the poleward edge of the cusp are associated with observed waves

trace metal geochemistry of sediments from baffin bay the major si al ti fe mn ca mg and trace metal zn cu pb co ni cr v li cd hg compositions of surficial sediments from baffin bay and the sounds lancaster jones smith leading into the arctic ocean have been determined the sediment composition varies regionally and in response to textural variations and the heavy metal concentrations are at or near natural levels in relation to their source rocks and other uncontaminated shelf and oceanic sediments chemical partition indicates that most of the heavy metal concentrations 80 99 except for cd 27 71 are derived from various sulphide oxide and silicate minerals the host minerals are predominantly fine grained and have accumulated at the same rate as other detrital clastic material of comparable grain size as a result the highest trace metal concentrations occur in the fine grained sediments occupying the deepest parts of the sounds and baffin bay although most of the metals have reached their depositional site by water transpo

regional scale co seismic landslide assessment using limit equilibrium analysis abstract traditionally regional assessment of seismic slope stability has been done using the infinite slope rigid sliding block analysis a major disadvantage of this approach is the resulting overestimation of the critical acceleration of the slope due to the underlying assumption of a predefined slope failure plane and consequently the underestimation of hazard areas prone to sliding in this paper we present a modified approach for assessing seismic slope instabilities using a model based on limit equilibrium analysis and circular slip surfaces with no restriction to any predefined slope failure plane for this purpose we conduct a parametric study to identify the relationship between the critical acceleration of the slope the slope angle and the slope shear strength parameters we model typical slopes in the rocscience software slide using bishop s limit equilibrium method to identify the critical accelerations that corresponds to a failure plane with factor of safety equal to one the critical accelerations were plotted against the variables in the parametric study and the best fit equations were obtained the proposed approach was developed for global application but it was tested using the well documented co seismic landslide database of the 1994 northridge ca earthquake the predicted sliding areas were compared to the inventory of landslides that were triggered in the val verde region in los angeles by the earthquake qualitative and quantitative assessments of the proposed model clearly show its advantages in predicting potential sliding areas

case history of landslide movement during the northridge earthquake we document a case history of northridge earthquake induced movement of a coherent landslide mass comprised principally of weathered previously sheared siltstone information on the residual shear strength of the material through which the sliding occurred is available both from backanalysis of a static rainfall induced failure on the same slope and laboratory test data postearthquake field reconnaissance data establishes the seismic slope displacements near the slope crest a yield coefficient is estimated for the slope based on residual shear strengths and measured groundwater levels at the time of the northridge earthquake this yield coefficient is used with four horizontal equivalent acceleration time histories that approximate the seismic demand within the slide mass in newmark sliding block displacement analyses the calculated displacements range from approximately 20 to 90 mm which compares well with observed displacements at the slide scarp of approximately 50 mm

a case study of upstream wave transmission to the ground at polar and low latitudes 1 in this study we analyzed a long duration ulf wave event detected on 18 19 february 2005 by cluster satellites upstream of the nose of the bow shock the availability of simultaneous data from geotail satellite located in the foreshock region close to the dawn flank of the bow shock allowed us to make a comparison between the observations at the two different sites the results can be explained in terms of local wave generation depending on the orientation of the interplanetary magnetic field with respect to the local bow shock normal in addition simultaneous data from polar satellite in the inner magnetosphere and from ground stations in the southern polar cap and at low latitude allowed us to investigate the transmission of the external waves through the magnetosphere up to the ground the observations suggest different paths of transmission waves generated upstream of the bow shock nose directly transmit near the subsolar point progressively propagate into the magnetosphere and after conversion into field guided alfven modes reach the ground at high and low latitudes waves generated on the flanks of the bow shock do not affect the subsolar magnetosphere and consequently there is no propagation along the closed field lines at both high and low latitudes on the other hand near the geomagnetic pole the occurrence of pulsations can be related to the transmission across the magnetopause flanks of upstream waves anywhere generated as they are convected downstream by the solar wind the compressional waves do not propagate deeply into the tail lobes but can couple to alfven guided waves along the outermost field lines

centrifuge modeling of dynamic response of high fill slope by using generalized scaling law abstract the development of physical modeling for mega engineering prototypes requires sophisticated use of the capability of current centrifuge facilities in this study centrifuge model tests were performed to investigate the dynamic response of high fill slope by using generalized scaling law in an improved way firstly the two stage generalized scaling law was partly re organized by considering the separate similitude of dynamic strain for the virtual 1 g field to solve the inherent problem of the scaling of soil strain when the derived prototype strain exceeded some important thresholds then a series of centrifuge model tests were conducted under different centrifugal accelerations to model a high fill slope with a prototype height of 100 m by the approach of modeling of models dynamic responses under sine waves with different amplitudes were monitored and the re organized generalized scaling law was validated for nonlinear dynamic response with shear strain less than 1 it was observed that site amplification of high fill slope was affected by both soil nonlinearity and soil strata non uniformity where soil nonlinearity led to smaller acceleration amplification under stronger excitation and soil strata non uniformity contributed to the acceleration de amplification and larger displacement amplification at the weak sublayer the large dynamic displacement near the slope surface consequently contributes to the development of lateral cracks after strong shaking seismic response under earthquake motions revealed that high fill slope with inclined non uniform strata was characterized by multiple vibration modes and lower fundamental frequency which was more vulnerable to earthquake motions with abundant frequency components this study provides a more physically meaningful use of the similitude of dynamic stress strain relation in centrifuge modeling for large scale geotechnical problems under dynamic loadings

arsenic trace metals and organic micro contaminants in sediments from the pechora sea russia grain size material 63 m toc tn pahs and organochlorines and the major al and fe and trace as cd cr cu hg li mn ni pb v and zn elements have been determined for grab and core samples from the southeast part of the barents sea known as the pechora sea russia most of the organic matter appears to be of marine origin but a terrestrial origin for om is indicated for the coastal areas in the vicinity of the pechora estuary all organic micro contaminant concentrations except lindane were low lithium normalization of cd cr cu hg ni pb v and zn concentrations indicates that they are at or near natural levels as a result of natural granular and mineralogical variability in the sediments high levels of arsenic however occur in fine grained surface and subsurface sediments the as enrichment is most likely due to the deposition and post depositional modification of as rich radioactive particulate material dispersed into the pechora sea by underwater nuclear explosions in guba chernaya on the southwest coast of novaya zemlya during the 1950s and 1960s

evaluation of surficial stability for homogeneous slopes considering rainfall characteristics shallow slope failures in residual soil during periods of prolonged infiltration are commonly occurring in the world this study examines an infinite slope analysis to estimate the influence of infiltration on surficial stability of slopes by the limit equilibrium method an approximate method that accommodates the boundary condition of a uniform rainfall has been proposed to evaluate the likelihood of shallow slope failure that is induced by a particular rainfall event the method based on the mein and larson model which provides an explicit solution for preponding infiltration has been applied to various types of soil having measured unsaturated hydraulic properties to compare results with those obtained from the approximate method a series of numerical analyses were carried out according to the results with the use of properly estimated input parameters the approximate method was found to give results that compare reasonably well with those of more rigorous finite element analyses

a scenario study of seismically induced landsliding in seattle using broadband synthetic seismograms abstract we demonstrate the value of utilizing broadband synthetic seismograms to assess regional seismically induced landslide hazard focusing on a case study of an m w 7 0 seattle fault earthquake in seattle washington we computed broadband synthetic seismograms that account for rupture directivity and 3d basin amplification we then adjusted the computed motions on a fine grid for 1d amplifications based on the site response of typical geologic profiles in seattle and used these time series ground motions to trigger shallow landsliding using the newmark method the inclusion of these effects was critical in determining the extent of landsliding triggered we found that for inertially triggered slope failures modeled by the newmark method the ground motions used to simulate landsliding must have broadband frequency content in order to capture the full slope displacement we applied commonly used simpler methods based on ground motion prediction equations for the same scenario and found that they predicted far fewer landslides if only the mean values were used but far more at the maximum range of the uncertainties highlighting the danger of using just the mean values for such methods our results indicate that landsliding triggered by a large seattle fault earthquake will be extensive and potentially devastating causing direct losses and impeding recovery the high impact of landsliding predicted by this simulation shows that this secondary effect of earthquakes should be studied with as much vigor as other earthquake effects online material high resolution maps of relative seismically induced landslide hazard for an m w 7 0 seattle fault earthquake for dry and saturated soil conditions

earthquake response of reinforced segmental retaining walls backfilled with substantial percentage of fines abstractthis paper reports on the seismic performance of three geosynthetic reinforced segmental retaining wall systems backfilled with a silty sand mixture using a shaking table excited by 1995 kobe earthquake loadings the preparation of the backfill mixture and its properties the tested wall configurations the reinforcement layouts and instrumentations and the observed wall performance are described visual observations and test results indicate that walls having 0 4 m vertical reinforcement spacing backfilled with soil containing a large percentage of fines performed better than those having good quality sandy soil under otherwise identical conditions vertical spacing of 0 8 m with removal of interlocking facing blocks in one of the walls did not lead to global collapse under repeated applications of the kobe earthquake loadings only localized shear failure behind the top block layer was observed as the top facing blocks tended to topple the good performance was attributable to apparent cohes

ulf geomagnetic pulsations in the southern polar cap simultaneous measurements near the cusp and the geomagnetic pole 1 during november 2003 a 1 week test campaign of ulf geomagnetic field measurements was conducted at the new italian french base of concordia dome c antarctic plateau close to the geomagnetic pole at a corrected geomagnetic latitude of 89 s an analysis of these measurements is presented together with a comparison with simultaneous measurements conducted at the italian mario zucchelli base at terra nova bay also located in the polar cap but at lower latitude 80 s the variable solar wind and interplanetary magnetic field conditions made it possible to monitor the pc 3 4 ulf pulsation activity under different magnetospheric conditions for quiet conditions the pulsation power does not show evidence for a diurnal modulation at dome c while at terra nova bay it maximizes around local magnetic noon this result can be interpreted in terms of the different latitude of the two stations which might be linked to different magnetospheric regions dome c deep in the polar cap and terra nova bay approaching the cusp around noon conversely during a strong geomagnetic storm the wave activity at the two stations becomes very similar and major ground manifestations are driven by strong solar wind pressure pulses the clear dependence of the pulsation frequency with the interplanetary magnetic field strength suggests that upstream waves can be the source of pulsations not only at terra nova bay but also at dome c in the deep polar cap we also find a clear relationship between the pulsation power and the solar wind speed which is more pronounced at dome c where cusp related phenomena are not present

polycyclic aromatic hydrocarbons pahs and pb isotopic ratios in a sediment core from shilianghe reservoir eastern china implying pollution sources the history records of polycyclic aromatic hydrocarbons pahs lead and its stable isotope ratios were determined in a sediment core to receive anthropogenic impacts on the shilianghe reservoir in eastern china the historical changes of pahs concentrations pahs fluxes pb al and pb isotope ratios showed a synchronous trend throughout the core suggesting changes in energy usage and correlating closely with the experience of a rapid economic and industrial development of the catchment linyi city in eastern china pahs isomer ratios results reveal pahs in sediments are dominantly anthropogenic pyrogenic source dominated by the combustion of coal and biomass furthermore the pb isotopic composition also clearly indicates that coal combustion dust mainly contributed to the pb burden in the reservoir sediments based on mix end member model of pb isotope ratios coal combustion dust dominated anthropogenic pb sources over fifty years contributing from 31 to 62 of total pb in sediment and the contribution of leaded gasoline was low than average 25 in addition a stable increase of coal combustion source was found in sediment core while the contribution of leaded gasoline had declined in recent decades with the phase out of leaded gasoline in china c 2015 elsevier ltd all rights reserved

simplified method for evaluating seismic stability of steep slopes steep slopes composed of weakly cemented granular soils are common along the pacific coast of north america these slopes standing at angles of 30 to near vertical are observed to be prone to seismically induced failures the steep topography of these slopes makes them particularly susceptible to amplification of seismic waves and the brittle nature of these materials make deformation based stability analyses inappropriate in this paper a simplified method is presented for assessing the seismic stability of these slopes utilizing average seismic coefficients to account for the effect of topography this procedure is based on a review of field and laboratory observations as well as analyses carried out using generalized consistent transmitting boundaries the results of the analyses indicate that the amplification due to the soil column in the free field behind the crest dominates the response the amplification due to topography on the other hand shows little variability and is on the order of 50 the proposed procedure presented herein gives practicing engineers a method to conduct stability analyses that better represents the actual field conditions for these steep brittle slopes

simplified procedure for estimating seismic slope displacements for subduction zone earthquakes abstractseismic slope displacements are estimated for earth structures or natural slopes subjected to interface earthquakes in subduction zones the fully coupled nonlinear seismic slope displacem

critical slip surface and landslide volume of a soil slope under random earthquake ground motions finding the critical slip surface and estimating the landslide volume are of primary importance for slope seismic design however this may be difficult due to the uncertainty of ground motions to address this problem a new method for calculating uncertainties is recommended in this paper especially for the critical slip surface and landslide volume under random earthquake ground motions firstly a series of intensity frequency nonstationary random earthquake ground motions were generated based on an improved orthogonal expansion method a given number of potential slip surfaces were set in a soil slope subsequently the factor of safety fos of each slip surface for all ground motions was calculated and the minimum fos curves were obtained it was found that the critical slip surfaces and failure times are uncertain under different earthquakes the monte carlo method was used to verify the accuracy of probability density evolution method pdem and the results of the pdem and the monte carlo method are consistent meaning that the pedm has higher computational efficiency moreover the distributions of earthquake triggered landslide volume and landslide depth were analyzed by considering equivalent extreme events both landslide volume and depth exhibit a normal distribution for a homogeneous soil slope the framework of this study is meaningful for slope seismic design in engineering for example the location of critical slip surface can be used for slope reinforcement and the distribution of sliding volume can be used for disaster assessment

the 2002 denali fault earthquake alaska a large magnitude slip partitioned event the mw moment magnitude 7 9 denali fault earthquake on 3 november 2002 was associated with 340 kilometers of surface rupture and was the largest strike slip earthquake in north america in almost 150 years it illuminates earthquake mechanics and hazards of large strike slip faults it began with thrusting on the previously unrecognized susitna glacier fault continued with right slip on the denali fault then took a right step and continued with right slip on the totschunda fault there is good correlation between geologically observed and geophysically inferred moment release the earthquake produced unusually strong distal effects in the rupture propagation direction including triggered seismicity

dynamic centrifuge testing of slickensided shear surfaces movement along preexisting slickensided rupture surfaces in overconsolidated clay and clay shale slopes can represent a critical sliding mechanism during earthquakes the seismic behavior of preexisting slickensided surfaces in overconsolidated clay was examined by performing dynamic centrifuge model tests of two slickensided sliding block models constructed using rancho solano lean clay dynamic shear displacements were concentrated along the preformed slickensided surfaces the peak shear resistances mobilized along the slickensided surfaces during dynamic loading were 90 120 higher than the drained residual strength measured prior to shaking to accurately predict the displacements of the sliding blocks using newmark s method it was necessary to use dynamic strengths that were 37 64 larger than the drained residual strength of the soil dynamic loading caused a positive pore pressure response in the soil surrounding the slickensided planes the postshaking shear strengths were 17 31 higher than those measured prior to shaking

pc3 pulsations in the polar cap and at low latitude 1 we present a statistical analysis of pc3 4 pulsations during 2005 at two polar cap stations terra nova bay and dome c antarctica and for comparison at a low latitude station l aquila the analysis technique allows to discriminate the signal component from the background noise in the power spectrum and to determine the frequency of such ulf signal commonly associated to the upstream wave source the comparison of data makes evident that the characteristics of the ulf pulsations are different at low and high latitudes and significant differences emerge also between the two polar cap stations at dome c the ulf signals are observed during the whole day while at terra nova bay and at l aquila the signals are mainly observed in the dayside sector the different cone angle dependence at l aquila and dome c the steeper slope in the frequency dependence on the interplanetary magnetic field strength at dome c with respect to l aquila and terra nova bay and the time dependence of the coherence between pulsations at the antarctic stations suggest that at low latitude waves are transmitted to the ground from a region close to the subsolar bow shock while near the geomagnetic pole waves are mainly transmitted through the magnetotail lobes at terra nova bay where the local field lines approach the cusp around noon and are stretched into the magnetotail around midnight the transmission path seems to be time dependent with daytime and nighttime pulsations penetrating through the subsolar point and via the magnetotail lobes respectively

initiation and displacement of landslide induced by earthquake a study of shaking table model slope test landslide researches often focus on factor of safety critical acceleration and displacement for an earthquake induced landslide the initiation and displacement of the landslide were important factors for definition of failure in this research the shaking table model slope test is adopted for study of slope failure initiation based on analyses of limit equilibrium particle image velocimetry piv analysis and acceleration time history recorded within the model slope based on the analyses landslide initiation could be defined as surface and local movement of the slope slope failure could be defined based on the massive movement of the slope the piv analysis provides good information for identifying both surface movement and massive movement the landslide displacement determined from the slope movement provides consistent results compared to observed displacements

evolution of the aqueous geochemistry of mine pit lakes blanzy montceau les mines coal basin massif central france origin of sulfate contents effects of stratification on water quality abstract the flooding of two mine pit lakes lake st louis and lake fouthiaux situated in the blanzy montceau les mines coal basin massif central france has been under close scrutiny for 5 a the aim was to understand i what sources can influence the lake water geochemistry ii what is the role of lake stratification on water chemistry iii how the lake water chemistry evolves during flooding to answer these questions t conductivity ph and eh depth profiles were measured with a specific probe seabird in the lakes seven surveys between july 1998 and february 2002 at the same time water samples were collected every 5 m along the profiles and were analysed for na ca2 k mg2 so 4 2 no 3 f cl hco 3 fe cu ni zn co cd and mn the geological and hydrogeological contexts play a major role on the water chemistry of the lakes and three sources of influence have been distinguished i the contribution of underlying mine groundwater enriched in so 4 2 due to the leaching of sulfide oxidation products from old flooded underground works ii the seepage through coal mine spoils also containing sulfides iii to a lesser extent triassic formations containing gypsum present in the fouthiaux area which lead to a so 4 2 enrichment of lake waters all these influences result in an enrichment in so 4 2 showing essentially a neutralised acid mine drainage process that is characterised by neutral to slightly alkaline waters and an absence of high metal contents except for fe and mn which are non soluble at the ph and eh conditions present in the lakes the two studied lakes were initially meromictic and ions such as so 4 2 or mn can show high concentrations at depth in the lake layers which are not subject to winter mixing during the studied period lake st louis remained meromictic and non removed elements continue to have high concentrations in deep zones in contrast lake fouthiaux initially meromictic became holomictic with time and the bottom layer did not maintain the enrichment in so 4 2 mn and other elements shown at the beginning

motions of gently sloping ground during earthquakes 1 during past earthquakes gently sloping ground surfaces have been observed to shift laterally over areas as large as a few square kilometers these permanent downward motions have been attributed to temporary and partial reductions in shear strength of soil deposits e g liquefaction static gravity forces and transient earthquake shakings these motions the amplitudes of which remain challenging to predict have been frequently modeled using newmark sliding blocks for ground that is statically stable and occasionally partially or completely loses its shear strength during earthquakes this paper investigates in more details the deformations of gently sloping ground that becomes temporarily unstable under the combined effects of gravitational forces and earthquake shakings using a physical model we propose two definitions of earthquake contributions to the displacement of gently sloping ground which may include or not the effects of initial velocity in both cases monte carlo simulations reveal that motions of gently sloping ground are influenced by pulses of earthquake ground velocity for a wide range of reduction in soil shear strength even for very severe loss of shear strength for practical purposes when large soil deposits become unstable during earthquakes the analysis concludes that the motions of gently sloping ground are likely influenced by earthquake ground velocity

high altitude cusp flow dependence on imf orientation a 3 year cluster statistical study 1 we report on the statistical properties of the plasma flows measured by the cluster spacecraft in the high altitude cusp region of the northern hemisphere as a function of the interplanetary magnetic field imf orientation with selected clock angle intervals the technique uses a magnetic field model taking into account the actual solar wind conditions and level of geomagnetic activity in order to model the magnetopause and cusp displacements as a function of these conditions the distributions of the magnetic field vector show a clear consistency with the imf clock angle intervals chosen and demonstrate that the technique used here fixes the positions of the cusp boundaries adequately the antisunward convection observed in the exterior cusp suggests that this region is statistically quite convective under southward imf while for northward imf the region appears more stagnant the presence of large parallel downward flows at the equatorward edge of the cusp shows that plasma penetration occurs preferentially at the dayside low latitude magnetopause for southward imf conditions in contrast under northward imf the results are suggestive of plasma penetration from the poleward edge of the cusp combined with a substantial sunward convection but no flows are observed at all at the dayside boundary with the plasma sheet the comparison of the measured flow speed with the alfven speed suggests that the magnetosheath adjacent to the external boundary is more sub alfvenic even for high magnetic latitudes under northward imf than under southward imf this result is consistent with the preference for the plasma depletion layer to develop under such conditions the transverse plasma convection in the exterior cusp appears to be controlled by the imf by component as well for dawnward duskward imf orientations the convection is preferentially directed toward dusk dawn these results are interpreted as strong arguments in favor of the cusp being structured at large scales by the occurrence of magnetic reconnection at the high latitude magnetopause for northward imf and at the low latitude magnetopause for southward imf

evaluation of simplified methods for predicting earthquake induced slope displacements in earth dams and embankments abstract this paper provides a review and comparison of existing simplified displacement based sliding block models analyses were performed to evaluate the relative accuracy of fifteen of these simplified models for predicting earthquake induced displacements to accomplish this task the predictive capability of the models was assessed by comparing model predictions with the actual displacements that were observed after earthquake shaking in 122 case histories of earth dams and embankments the results indicate that the model predictions of displacement were less than the observed displacement for a large majority of the case histories that were examined the difference between the observed and predicted displacements was relatively large for a significant percentage of the cases for each model that was examined the shapes and positions of the models relative error cumulative distribution functions did not change significantly if the case histories were filtered to include only those with intermediate levels of observed displacement i e 0 01 m

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

ecological risk assessment of the assaluyeh and bassatin estuaries northern persian gulf using sediment quality indices abstract the assaluyeh and bassatin estuaries are located in nayband bay in the northern persian gulf which faces long term contamination and ecological risks the research objectives of this study were designed to assess the ecological risks for human health and aquatic life and to evaluate impacts on environmental changes accordingly an index analysis approach using the contamination factor c f contamination degree c d potential ecological risk factor for individual metals e r and potential ecological risk index for the basin ri in conjunction with the enrichment factor e f and sediment quality levels comprised of the threshold effect level tel the probable effect level pel and the effects range medium erm were employed in total 147 sediment samples were tested to determine the content of organic matter and sulfur as well as the concentrations of terrestrial and rare earth elements rees and toxic metals namely as cd cr cu ni and hg using inductively coupled plasma optical emission spectroscopy icp oes gulf war oil spills in addition to oil and gas industries of the pars south especial economic zone pseez were identified as the primary source of pollution in the study area gulf war contamination in the study area is highlighted by increased levels of c d and ri at key horizons at 29 cm 35 cm and 49 cm depth in the sedimentary columns of the assaluyeh and bassatin estuaries and gavbandi river respectively adverse effects of pseez were revealed by increasing concentrations of toxic metals p and s in the top 25 30 cm of the sedimentary columns as a result superficial sediments have been severely polluted by as ni cd cu and cr while the entire sedimentary column of the assaluyeh estuary has been polluted by hg based on the locations of the key horizons the sedimentation rates of the previous decade at the assaluyeh and bassatin estuaries and the gavbandi river were calculated to be 1 26 cm 1 52 cm and 2 13 cm respectively the capability of the index analysis approach as well as of certain lanthanides for highlighting environmental evolutionary trends in catchments in which extensive land use changes have occurred was demonstrated by the present investigation the present research concluded that aquatic life and human health in the study area have been subjected to different ranges of hazards by toxic metals due to regional and local anthropogenic activities

simplified methodology for consideration of two dimensional dynamic response of levees in liquefaction triggering evaluation abstractlevees are very challenging engineering structures to study in part because they are not typically well engineered structures unfortunately there is little to no guidance as to how to evaluate the seismic vulnerability of levees this study focuses on systematically studying the dynamic response of levees using a wide range of input ground motions and developing a simplified procedure for the liquefaction triggering evaluation of earthen levees accounting for the dynamic response of the levee the study was based on three levee sites representative of three select california central valley regions however because floodplains tend to generally have similar depositional environments the study can be extended to other regions as long as some of the principal characteristics are still applicable a wide range of input ground motions was used to capture and assess the variability in response and performance because of multiple possible earthquake scenarios two aspects of the dynamic response an

topographic effects on the seismic response of steep slopes a frequency domain parametric study using generalized consistent transmitting boundaries has been performed to evaluate the significance of topographic effects on the seismic response of steep slopes the results show that the peak amplification of motion at the crest of a slope occurs at a normalized frequency h 0 2 where h is the slope height and is the wavelength of the motion the importance of the natural site frequency is illustrated by the analysis of a stepped layer over a half space it was found that the natural frequency of the region behind the crest can dominate the response relative to the topographic effect for the conditions studied moreover the effect of topography can be handled separately from the amplification due to the natural frequency of the deposit behind the crest of the slope this concept of separating the amplification caused by topography from that caused by the natural frequency is advantageous to the development of a simplified method to estimate topographic effects

centrifuge model testing of a loess landslide induced by rising groundwater in northwest china abstract considerable artificial irrigation in the heifangtai area has caused the continued rise of groundwater levels which has resulted in several large scale landslides in the loess platform area considering the no 13 landslide of jiaojia in the heifangtai area as a geological archetype a series of centrifuge tests was conducted to study the deformation and failure characteristics of the slope due to the continuous rise in the groundwater level meanwhile the pore water pressure earth pressure deformation and evolution characteristics of the slope were monitored and recorded in real time furthermore isotropically consolidated undrained triaxial testing icu was conducted to investigate the static liquefaction of loess specimens which was related to the slope instability the centrifuge test results showed that a series of parallel and steep tension cracks at the top of the slope were present before the landslide which was caused by the rising groundwater the icu experimental results showed that as the pore water pressure increased strong strain softening and static liquefaction of saturated loess soils were found which was related to the sudden destruction of the slope

hydrocarbons in washington coastal sediments the sources and distributions of polycyclic aromatic hydrocarbons pah and aliphatic hydrocarbons are characterized in seventeen sediments from a highly river influenced sedimentary environment off the southwestern coast of washington the major hydrocarbons are land derived introduced as preformed compounds and display long term stability in sediment cores a series of pah of anthropogenic origin and two naturally derived compounds retene and perylene dominate the pah composition in these sediments plantwax n alkanes are the major aliphatic hydrocarbon constituents aliphatic hydrocarbons of marine origin pristane and a series of four acyclic multibranched c25 polyolefins are also observed in many sediments the concentrations of these marine derived hydrocarbons decrease to negligible levels rapidly with sediment depth from the sea sediment interface suggesting degradation in general the major land derived hydrocarbons are concentrated in the midshelf silt deposit which extends northwestward along the continental shelf from the columbia river mouth a quantitatively more minor natural series of phenanthrene homologs also of terrestrial origin is preferentially advected further offshore and deposited in continental slope sediments these distributions are consistent with recognized particle associations for these compounds and sediment dispersal processes in this coastal environment sediment core records suggest the present pattern of dispersal has persisted for at least the past century and possibly since the late pleistocene

seismically induced rock slope failures resulting from topographic amplification of strong ground motions the case of pacoima canyon california abstract the 1994 northridge earthquake mw 6 7 triggered extensive rock slope failures in pacoima canyon immediately north of los angeles california pacoima canyon is a narrow and steep canyon incised in gneissic and granitic rocks peak accelerations of nearly 1 6 g were recorded at a ridge that forms the left abutment of pacoima dam peak accelerations at the bottom of the canyon were less than 0 5 g suggesting the occurrence of topographic amplification topographic effects have been previously suggested to explain similarly high ground motions at the site during the 1971 mw 6 7 san fernando earthquake furthermore high landslide concentrations observed in the area have been attributed to unusually strong ground motions rather than higher susceptibility to sliding compared with nearby zones we conducted field investigations and slope stability back analyses to confirm the impact of topographic amplification on the triggering of landslides during the 1994 earthquake our results suggest that the observed extensive rock sliding and falling would have not been possible under unamplified seismic conditions which would have generated a significantly lower number of areas affected by landslides in contrast modelling slope stability using amplified ground shaking predicts slope failure distributions matching what occurred in 1994 this observation confirms a significant role for topographic amplification on the triggering of landslides at the site and emphasises the need to select carefully the inputs for seismic slope stability analyses

modified newmark model for seismic displacements of compliant slopes newmark sliding block analyses are widely used for estimation of permanent displacements of slopes in earthquakes the conventional newmark model however neglects the dynamic response of the material above a potential failure surface decoupled procedures have been developed to account for that response but they neglect the effects of permanent displacements on the response a modified newmark analysis that considers the dynamic response including the effects of permanent displacements of the material above the failure surface is presented the modified newmark analysis shows that the decoupled approach produces somewhat conservative estimates of permanent displacements for stiff and or shallow failure masses but that it may produce unconservative estimates for failure masses that are soft and or deep many slopes of large lined landfills may fall into this latter category the notion of a slope spectrum which illustrates the effect of the natural period of a potential failure mass on permanent slope displacement is also introduced

methods for assessing the stability of slopes during earthquakes a retrospective abstract during the twentieth century several methods to assess the stability of slopes during earthquakes were developed pseudostatic analysis was the earliest method it involved simply adding a permanent body force representing the earthquake shaking to a static limit equilibrium analysis stress deformation analysis a later development involved much more complex modeling of slopes using a mesh in which the internal stresses and strains within elements are computed based on the applied external loads including gravity and seismic loads stress deformation analysis provided the most realistic model of slope behavior but it is very complex and requires a high density of high quality soil property data as well as an accurate model of soil behavior in 1965 newmark developed a method that effectively bridges the gap between these two types of analysis his sliding block model is easy to apply and provides a useful index of co seismic slope performance subsequent modifications to sliding block analysis have made it applicable to a wider range of landslide types sliding block analysis provides perhaps the greatest utility of all the types of analysis it is far easier to apply than stress deformation analysis and it yields much more useful information than does pseudostatic analysis

the effects of normal and shear stress wave phasing on coseismic landslide displacement predictive models used to assess the magnitude of coseismic landslide strain accumulation in response to earthquake ground shaking typically consider slope parallel ground accelerations only and ignore both the influence of coseismic slope normal ground accelerations and the phase relationship between dynamic slope normal and slope parallel accelerations we present results of a laboratory study designed to assess the significance of the phase offset between slope normal and slope parallel cyclic stresses on the generation of coseismic landslide displacements using a dynamic back pressured shearbox that is capable of simulating variably phased slope normal and slope parallel dynamic loads we subjected sediment samples to a range of dynamic loading scenarios indicative of earthquake induced ground shaking we detail the variations in strain accumulation observed when slope normal and slope parallel stresses occur independently and simultaneously both in and out of phase using a range of dynamic stress amplitudes our results show that the instantaneous phasing of dynamic stresses is critical in determining the amount of coseismic landslide displacement which may vary by up to an order of magnitude based solely on wave phasing effects instantaneous strain rate is an exponential function of the distance normal to the mohr coulomb failure envelope in plots of shear stress against normal effective stress this distance is strongly controlled by the phase offset between dynamic normal and shear stresses our results demonstrate that conditions considered by conventional coseismic slope stability models can either overestimate or underestimate earthquake induced landslide displacement by up to an order of magnitude this has important implications for accurate assessment of coseismic landslide hazard

centrifugal modeling of seismic behavior of large diameter pipe in liquefiable soil this study focused on the behavior of a large diameter burial pipe with special reference to its stability against flotation subject to soil liquefaction centrifugal modeling technique was used where the results are presented for a total of eight shaking table tests conducted on the burial pipe in a laminar box under 30g gravitational field the ground was prepared with nevada sand at a relative density of 38 and shaken with a sinusoidal wave at an amplitude of 0 5g the use of a viscous fluid in a saturated soil deposit satisfied the time scaling relationships of both dynamic and dissipation phenomena the centrifugal modeling technique simulated flotation of pipeline as the soil liquefied a technique that used gravels and geosynthetic material was used to mitigate flotation the response of the soil deposit in terms of acceleration and excess pore pressure was investigated the uplifting of the pipe earth pressure response and ground surface deformation were also presented based on the test results a design procedure was proposed for the burial pipe in resisting flotation due to soil liquefaction the deadweight and stiffness of the gravel unit which was confined by geosynthetic were important items in design

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

evaluation of factors controlling earthquake induced landslides caused by chi chi earthquake and comparison with the northridge and loma prieta events over 10 000 landslides were triggered by the september 21 1999 chi chi earthquake a large number of these landslides have been mapped from spot images and a smaller number were described in a detailed field investigation geographic information systems gis was used to conduct a spatial characterization of the slope failures including distribution of type size slope angle bedrock geology ground motion and distance from earthquake source the most abundant landslides were shallow disaggregated rock and soil slides landslides occurred primarily in tertiary sedimentary rocks which are well known for their susceptibility to landsliding in many parts of the world landslide concentration values diminish beyond epicentral distances of 40 and 70 km from the epicenter and the surface projection of the fault plane respectively ground motion was found to be the most significant factor in triggering the shallow landslides in the chi chi earthquake overall 74 of all slope failures occurred in regions with vertical ground motions greater than 0 2g and 81 of all slope failures occurred in the region with mean horizontal peak ground accelerations pga greater than 0 15g these factors were used to compare landslides generated by the chi chi earthquake to the landslides triggered by the 1989 loma prieta earthquake and the 1994 northridge earthquake the major difference in distribution of landslides between the chi chi earthquake and the two california earthquakes was the distribution of slope angles in the chi chi earthquake 90 of the failures occurred on slopes steeper than 45 while more than 80 of failures occurred on slopes less than 50 in california apparently reflecting much steeper and tectonically more active geologic setting in taiwan

experimental and numerical investigations of the seismic response of a rock soil mixture deposit slope inertial instability induced slope failure is one of the most destructive seismic hazards encountered in china depositional slopes are widely distributed across the south western part of china to study the seismic performance of rock soil mixture deposit rsmd slopes in detail physical and mechanical tests of air dried rsmd and a 1 50 geometric scale generalised rsmd slope centrifugal shaking table modelling tests were conducted the acceleration response slope deformation and instability mode of the air dried rsmd slope under the continuous action of four earthquakes with different intensities are analysed besides the dynamic finite difference numerical simulations were performed with flac to simulate the centrifuge model test the numerical simulation results were compared with the test results in terms of the horizontal acceleration response time history of crest settlements and the slope failure characteristics the results show that the horizontal peak ground acceleration pga amplification factors of the rsmd slope reflect typical elevation and surface amplification effects in addition the spectral distribution of the seismic wave has changed significantly with propagation along the slope elevation the energy of input seismic wave in a frequency range close to the natural frequency of an rsmd slope is significantly amplified during the test it was observed that the failure of an air dried rsmd slope occurred when the pga reached 0 216 g and the settlement at the crest of the slope was obvious the failure mode was dominated by shallow collapse

lateral spreading within a limit equilibrium framework newmark s sliding blocks with degrading yield accelerations lateral spreading is a prevalent geotechnical problem associated with earthquake induced liquefaction often occurring at gentle slopes of loose saturated sand near bodies of water and causing sig

assessment of earthquake induced landslide hazard in greece from arias intensity to spatial distribution of slope resistance demand abstract the earthquake induced landslide hazard in greece is evaluated by means of a parametric time probabilistic approach first by taking into account the characteristics of seismicity affecting greece we calculated occurrence probabilities for different levels of seismic shaking expressed in terms of arias intensity for a time interval of 50 yrs then by utilizing the linkage of newmark displacement with arias intensity and critical acceleration we mapped the spatial distribution of the slope strength demand that imply a 10 probability that displacement will exceed critical thresholds for potential seismic triggering of incoherent and coherent landslides the obtained results suggest that the areas of western greece and the broader region of the gulf of corinth are the most exposed to conditions of seismic triggering of both kinds of landslides the derived slope strength demand maps could provide the basis for the assessment of whether particular slopes have a significant failure probability by comparing the estimated strength demand with the actual critical acceleration values calculated from slope material properties and slope angle we exemplified this approach at a coastal area of the western gulf of corinth where by considering situations expected in dry and wet periods we also demonstrated that earthquake effects on slope stability depend on the season of earthquake occurrence

uncertainty in seismic slope deformation model predictions in this article we examine how variability in driving and resisting force parameters together translate into uncertainty in seismic slope deformation predictions predictive uncertainty of the newmark rigid block and makdisi seed decoupled deformation based methods was evaluated by performing a series of probabilistic monte carlo simulations for two idealized slope models results from these analyses demonstrate that the highly non linear relationship between acceleration ratio and displacement associated with the deformation models dictates the way in which parametric variability is propagated through the analysis and can lead to varying degrees of uncertainty in the deformation predictions based on this observation three zones along the displacement acceleration ratio relationship were identified according to their relative degree of non linearity and correlated with their relative influence on predictive uncertainty these are i highly uncertain ii moderately uncertain and iii low uncertainty using this framework the widely held notion of a generic order of magnitude estimate for deformation predictions is a misnomer based on this it is recommended that realistic levels of parametric variability be incorporated in the seismic slope deformation analysis to establish the operating conditions of the slope system slopes identified as highly uncertain or moderately uncertain require a more robust probabilistic analyses to meaningfully interpret poorly constrained deformation predictions

seismic triggering of catastrophic failures on shear surfaces in saturated cohesionless soils this paper is concerned with an analysis of the seismic performance of infinite slopes in undrained conditions the material assumed on the sliding surface is a loose saturated sand susceptible to a gradual loss in undrained shear strength after failure with the progress of unidirectional shear displacement the undrained monotonic and cyclic shear behavior of this sand was investigated through an experimental study based on ring shear tests with initial stresses corresponding to the static conditions on the sliding surface of the analyzed slopes these tests provide the experimental framework for a modified sliding block method to estimate the earthquake induced undrained shear displacements for conditions of no shear stress reversals on the sliding surface the proposed estimation procedure incorporates the shearing resistance obtained from undrained monotonic ring shear tests to approximate the undrained yield resistance at a certain displacement during an earthquake the term catastrophic failure is

geochemistry of surficial and ice rafted sediments from the laptev sea siberia the laptev sea as a part of the world s widest continental shelves surrounding the arctic ocean is a key area for understanding the land ocean interaction in high latitude regions with a yearly freshwater input of 511 km3 the lena river one of the eight major world rivers has an influencing control over the environment of this arctic marginal sea which is ice covered during most of the year in this paper the first measurements are presented of the major and trace element distribution within the 20 m grain size fraction of surficial sediments and of particulate matter in new and young ice from the laptev sea siberian arctic the concentration and distribution of major and trace elements have been determined in 51 surficial sediment samples covering the whole laptev sea shelf south of the 50 m isobath thirty one samples of particulate matter in newly formed ice were taken during the freeze up period in 1995 median concentration levels of heavy metals in surficial sediments ni 46 g g 1 cu 26 g g 1 zn 111 g g 1 and pb 21 g g 1 are within the concentration range of marine unpolluted sediments also the sediment laden ice showed no indication of anthropogenic perturbation of the trace metal inventory spatial distribution patterns of heavy metals are mainly determined by variation of mineral composition and different fluvial sediment sources in the eastern and western laptev sea the laptev sea shelf is cut by five north south trending submarine valleys enrichment of manganese in the oxic surficial sediment layer within these valleys and the occurrence of small ferromanganese nodules are caused by a high input of dissolved and particulate mn from the lena river and a strong diagenetic cycling of mn on the laptev sea shelf evidence is given that the content of as in surficial sediments is also strongly affected by diagenetic cycling this causes surficial sediment as concentrations of more than 100 g g 1 enrichment of mn and as was mainly observed in the submarine valleys distant from the major river mouth the sediment dilution due to higher sedimentation rates near the river outlets and a strong sediment re working by ice gouging in the shallow areas are the principle causes for the absence of diagenetic accumulation in this region during the formation of new ice scavenging of riverine suspended matter and resuspension of sediments followed by an incorporation of particles into the ice are important processes for the river shelf ocean transport of particulate trace elements it could be shown that particle loaded ice posseses the same geochemical signatures as the suspended matter and surficial seafloor sediments in the area of ice origin this has also strong implications for the contaminant transport on the arctic shelves and allows to use the geochemical signature of sea ice for the reconstruction of ice drift pattern within the arctic ocean

a sedimentary record of the deposition of heavy metals and magnetic oxides in the loch dee basin galloway scotland since c ad 1500 geochemical analyses of a 210pb dated piston core from loch dee have highlighted trends of increased pb and cu deposition within the catchment as early as ad 1500 probably as a consequence of local mining and smelting activity more marked atmospheric pollutant deposition appears to have occurred in association with european industrialization after c 1840 causing a conspicuous enhancement of pb zn cu and magnetically detectable fe oxide concentrations in the uppermost 8 cm of sediment the co variability of these contaminants through the surficial sediment suggests that they emanate from a common industrial process and the presence of magnetic oxides in cenospheric particulates implicates thermal power generation plant as a principal pollutant source this interpretation is further supported by the temporal comparability of trace metal magnetic oxide influxes at loch dee and documented records regarding european fossil fuel combustion levels over the past 150 years the reduced heavy metal concentrat

investigating the imf cone angle control of pc3 4 pulsations observed on the ground many studies have shown that pc3 4 pulsations 0 014 0 1 hz observed in earth s magnetosphere during daytime hours originate in the ion foreshock region of the solar wind just upstream from earth s bow shock they occur when the interplanetary magnetic field imf is primarily radial when the imf cone angle xb 45 however our knowledge of ion foreshock conditions is often incomplete because of the very limited number of spacecraft providing upstream data in this study we compared 13 months of wave observations at two widely separated ground stations hornsund svalbard and halley antarctica to imf values in the omni database in order to test this relation values of xb and the empirically predicted wave frequency fcalc 0 06 bimf were compared to daily fourier spectrograms displaying pulsation power and frequency although there was often good temporal agreement between low xb and increased pc3 4 wave power numerous counterexamples were also evident a statistical study of wave activity in quarter hour increments showed that pc3 4 pulsations were associated with low xb values 81 of the time at hornsund and 83 at halley imf cone angle data from all available upstream monitors were compared to wave observations for a more limited number of days many of these showed inconsistent imf orientations this study indicates some of the limitations of the existing upstream monitors and provides a quantitative estimate 80 of the accuracy of the omni data set in characterizing conditions near the nose of earth s bow shock under predominantly radial imf conditions

centrifuge modeling of slope instability this paper demonstrates the use of a centrifuge modeling technique in studying slope instability the slope models were prepared from sand and sand mixed with 15 and 30 fines by weight compacted at optimum water content the validity of the modeling technique was confirmed using slope models of different heights inclinations and soil types the soil behavior was studied under triaxial and plane strain conditions and the extended mohr coulomb failure criterion was found relevant for expressing the strength of unsaturated compacted soil based on the angle of internal friction and apparent cohesion the bishop s circular mechanism together with the extended mohr coulomb failure criterion was able to simulate the slope failure reasonably well the rainfall of different intensities was then induced on the 60 stable slopes of sand with 15 fines it was found that the failure of slope under rainfall may be interpreted as a reduction in apparent cohesion the centrifuge tests also allowed the rainfall intensity duration threshold curve local curve to be generated for the test slopes and the accumulated rainfall corresponded well to some of the reported field observations

analysis of topographic amplification of inclined shear waves in a steep coastal bluff abstract the effect of inclined shear waves on the seismic response of a steep bluff is analyzed using generalized consistent transmitting boundaries the results of the frequency domain analysis of a stepped half space subjected to incident shear waves inclined from 0 to 30 show that the motion at the crest of the slope is amplified for waves traveling into the slope and attenuated for waves traveling away from the slope as compared to the motion in the free field behind the crest of the slope this amplification can be as much as twice that observed for vertically propagating waves a time domain analysis of bluffs at seacliff state beach california is used to estimate the effect of topography using realistic conditions taking into account wave inclination and site effects the analysis of the site shows that although topographic amplification does in fact nearly double the amplitude of the motion in some cases this amplification is offset by reduced site amplification and by wave splitting at material interfaces thus the actual peak acceleration occurring at the crest of the slope changes little with incident angle as compared to the amplification of the free field motion and actually decreases in many cases though a more general study is recommended these results suggest that wave orientation and inclination substantially increase topographic amplification however it may be adequate to only account for vertically propagating waves for site response and slope stability analyses where only the magnitude of acceleration is considered

distribution and characteristics of loess landslides triggered by the 1920 haiyuan earthquake northwest of china abstract on december 16 1920 an earthquake with a magnitude of 8 5 occurred in haiyuan county ningxia hui autonomous region northwest of china this earthquake triggered several thousand loess landslides which resulted in thousands of deaths and blockages of rivers the distribution and characteristics of the landslides triggered by the haiyuan earthquake in loess areas were studied using satellite images and field investigation a total of about 3700 landslides with a cumulative area of about 177 km2 were interpreted over an area of 21 000 km2 it was found that landslides triggered by the earthquake were concentrated in a western of 40 55 km from the haiyuan fault landslides were concentrated near ridge crests with 65 7 of the landslides originating in the upper quadrant of slopes the aspects of the landslides triggered by the haiyuan earthquake were parallel to the faults and there is no back direction effect in landslides triggered by haiyuan earthquake these landslides have long run out distances travel distance l height different h 0 6 and deposited materials in river channels forming 51 dammed lakes that still exist the relationship between the area a and volume v of the landslides is v 4 170 a1 086 based on the relationship between number and volume of landslide and the magnitude of earthquake 100 000 landslides with a cumulative volume of 0 5 1010 m3 were triggered by the haiyuan earthquake as loess is sensitive to liquefaction during an earthquake and tends to produce landslides with long travel distances hence the loess depth slope and geological stresses are the primary factors responsible for the high density of landslides in this region

natural enrichment of arsenic in loch lomond sediments abstract concentrations of arsenic in surface or near surface sediment in 12 of 13 cores from the three major basins of loch lomond are substantially enhanced up to 675 mg kg compared with background values of 15 50 mg kg sedimentary as profiles are attributed to post depositional enrichment processes since there are no recent significant sources of environmental as contamination anthropogenic or natural in the loch lomond area the enrichments can be interpreted in terms of post depositional diagenetic remobilization processes in sediment reducing zones followed by upward migration of as through interstitial waters and oxidation adsorption precipitation reactions in near surface oxidizing layers confirmation of the diagenetic adsorption hypothesis is provided directly by the analysis of as species 1 5 81 g l in pore water and indirectly via comparison with sedimentary phosphorus

metal contamination and solid phase partitioning of metals in the stream and bottom sediments in a reservoir receiving mine drainage abstract this study was conducted to assess the anthropogenic impact on metal concentrations in the bottom sediments of the juam reservoir korea and in stream sediments in its catchment and to estimate the potential mobility of selected metals fe mn cu ni pb and zn using sequential extraction a comparison of the metal concentrations in the stream sediments with mean background values in sediments collected from first or second order creeks shows that pb cu and ni are the most affected by anthropogenic inputs the 206pb 207pb ratios of the bottom and core sediments means 1 2320 0 0502 and 1 2212 0 0040 respectively suggest that pb contamination is mainly due to the waste discharge of abandoned coal and metal mines rather than industrial and airborne sources considering the proportion of metals bound to the exchangeable carbonate and reducible fractions the comparative mobility of metals is suggested to decrease in the order mn pb zn ni fe cu

regression models for estimating coseismic landslide displacement newmark s sliding block model is widely used to estimate coseismic slope performance early efforts to develop simple regression models to estimate newmark displacement were based on analysis of the small number of strong motion records then available the current availability of a much larger set of strong motion records dictates that these regression equations be updated regression equations were generated using data derived from a collection of 2270 strong motion records from 30 worldwide earthquakes the regression equations predict newmark displacement in terms of 1 critical acceleration ratio 2 critical acceleration ratio and earthquake magnitude 3 arias intensity and critical acceleration and 4 arias intensity and critical acceleration ratio these equations are well constrained and fit the data well 71 br 2 b88 but they have standard deviations of about 0 5 log units such that the range defined by the mean one standard deviation spans about an order of magnitude these regression models therefore are not recommended for use in site specific design but rather for regional scale seismic landslide hazard mapping or for rapid preliminary screening of sites 2007 elsevier b v all rights reserved

amplification of seismic accelerations at slope crests earthquake accelerations can cause many problems in sloping ground one such problem is that accelerations are greatly amplified at the crest of slopes this topographic amplification can lead to a

stability analyses of rainfall induced landslides the slope stability issues concerning rainfall induced slope failures are investigated and presented specifically the effect of both negative and positive pore water pressures on the stability of initially unsaturated slopes are carefully explained and coupled with infinite slope analysis methods in order to present a predictive formulation of slope failures that occur as a result of rainfall events the formulation serves as a baseline analysis method for evaluating potentially unstable soil slopes that are subject to surface infiltration and explains the various triggering mechanisms that may occur based on individual combinations of the slope geometry soil strength and infiltration parameters a procedural method is outlined for utilizing the analytical formulation to predict the change in the factor of safety for a slope subject to infiltration and a detailed analysis of a case study is presented to verify the method quantitative statements are made concerning the time and depth of failure in relationship to the soil slope and rainfall parameters

simplified procedure for estimating earthquake induced deviatoric slope displacements a simplified semiempirical predictive relationship for estimating permanent displacements due to earthquake induced deviatoric deformations is presented it utilizes a nonlinear fully coupled stick slip sliding block model to capture the dynamic performance of an earth dam natural slope compacted earth fill or municipal solid waste landfill the primary source of uncertainty in assessing the likely performance of an earth waste system during an earthquake is the input ground motion hence a comprehensive database containing 688 recorded ground motions is used to compute seismic displacements a seismic displacement model is developed that captures the primary influence of the system s yield coefficient ky its initial fundamental period ts and the ground motion s spectral acceleration at a degraded period equal to 1 5 ts the model separates the probability of zero displacement i e 1 cm occurring from the distribution of nonzero displacement so that very low values of calculated

shaking table modeling of seismically induced deformations in slopes physical model experiments were performed on a 1 g shaking table with the principal goals of 1 investigating the mechanisms of seismically induced permanent deformations in slopes and 2 assessing the accuracy and applicability of the newmark sliding block procedure for estimating seismically induced deformations in slopes each of the clayey slope models deformed in response to strong shaking with the principal mode of deformation being deep rotational translational sliding displacement deformations were principally focused along one or more highly localized shear surfaces though a significant amount of additional deformation was also distributed over a relatively wide region of the models the newmark analyses generally provided moderately accurate although somewhat unconservative estimates of deformations displacements computed using the rigid sliding block analysis ranged from 27 to 225 of maximum measured displacements and averaged about 75 of measured displacements for the test series the newmark type analyses were most reliable for those model tests that experienced large deformations where the sliding resistance was controlled principally by postpeak to residual strengths

residual shear strength variability as a primary control on movement of landslides reactivated by earthquake induced ground motion implications for coastal oregon u s most large seismogenic landslides are reactivations of preexisting landslides with basal shear zones in the residual strength condition residual shear strength often varies during rapid displacement but the response of residual shear zones to seismic loading is largely unknown we used a ring shear apparatus to perform simulated seismic loading tests constant displacement rate tests and tests during which shear stress was gradually varied on specimens from two landslides to improve understanding of coseismic landslide reactivation and to identify shear strength models valid for slow gravitational failure through rapid coseismic failure the landslides we studied represent many along the oregon u s coast seismic loading tests resulted in 1 catastrophic failure involving unbounded displacement when stresses represented those for the existing landslides and 2 limited to unbounded displacement when stresses represented those for hypothetical dormant landslides suggesting that coseismic landslide reactivation may be significant during future great earthquakes occurring near the oregon coast constant displacement rate tests indicated that shear strength decreased exponentially during the first few decimeters of displacement but increased logarithmically with increasing displacement rate when sheared at 0 001 cm s 1 or greater dynamic shear resistance estimated from shear strength models correlated well with stresses observed during seismic loading tests indicating that displacement rate and amount primarily controlled failure characteristics we developed a stress based approach to estimate coseismic landslide displacement that utilizes the variable shear strength model the approach produced results that compared favorably to observations made during seismic loading tests indicating its utility for application to landslides

effects of near fault ground shaking on sliding systems a numerical study is presented for a rigid block supported through a frictional contact surface on a horizontal or an inclined plane and subjected to horizontal or slope parallel excitation the latter is described with idealized pulses and near fault seismic records strongly influenced by forward directivity or fling step effects from northridge kobe kocaeli chi chi aegion in addition to the well known dependence of the resulting block slippage on variables such as the peak base velocity the peak base acceleration and the critical acceleration ratio our study has consistently and repeatedly revealed a profound sensitivity of both maximum and residual slippage 1 on the sequence and even the details of the pulses contained in the excitation and 2 on the direction or in which the shaking of the inclined plane is imposed by contrast the slippage is not affected to any measurable degree by even the strongest vertical components of the accelerograms moreover the slippage from a specific record may often be poorly correlated with its arias intensity these findings may contradict some of the prevailing beliefs that emanate from statistical correlation studies the upper bound sliding displacements from near fault excitations may substantially exceed the values obtained from some of the currently available design charts

nested newmark model to calculate the post earthquake profile of slopes abstract the newmark sliding block approach is a common means of evaluating permanent displacements of slopes undergoing seismic loading however the conventional newmark approach omits the presence of multiple shear zones or regions of dispersed shear movement the occurrence of these shear movements within slopes can often materialize with added vertical and lateral movements above the basal failure surface typically considered in the conventional newmark approach this study modifies the conventional newmark sliding block approach by discretizing a given slope into a series of nested critical failure wedges each with an associated yield acceleration termed a nested newmark model nnm use of the nnm enables assessment of a post earthquake slope profile within a limit equilibrium framework based on the integration of relative displacements from the toe to the crest the results demonstrate a different response than conventional newmark approaches the model outputs can account for the restriction of toe movements as well as heaving and slumping behavior of the slope face and crest respectively larger seismic excitation resulted in further destabilization of nested wedges near the crest the presented approach establishes a framework that can be extended to any type of failure geometry or series of failures including rotational geometry these results are compared to a numerical model which exhibit similar behavior this framework is conceptual but builds upon the well accepted newmark sliding block approach to provide an alternative means of assessing post earthquake slope movements

stability analysis of slopes with ground water during earthquakes abstract heavy seismic damage tends to occur in embankments when ground water is present this paper proposes and applies a numerical procedure to evaluate slope stability during seismic loading seismic failure is herein defined to occur when a cumulative plastic deformation exceeds a critical value of deformation determined by static slope stability analysis the numerical procedure relies on finite element analysis of dynamic stress and deformation in slopes to assess their stability during earthquakes considering the effect of ground water level the performance of the proposed numerical procedure is assessed by applying it to evaluate the seismic slope stability of hypothetical and actual slopes affected by high ground water levels

nonlinear coupled seismic sliding analysis of earth structures earthquake induced sliding displacements of earth structures are generally evaluated using simplified sliding block analyses that do not accurately model the seismic response of the sliding mass nor the seismic forces along the slide plane the decoupled approximation introduced to capture each of these effects separately is generally believed to be conservative however recent studies using linear viscoelastic sliding mass models have revealed instances where the decoupled approximation is unconservative in this paper a coupled analytical model that captures simultaneously the fully nonlinear response of the sliding mass necessary for intense motions and the nonlinear stick slip sliding response along the slide plane is presented the proposed sliding model is validated against shaking table experiments of deformable soil columns sliding down an inclined plane the effect of sliding on the response of earth structures is evaluated and comparisons are made between sliding displacements calculated us

investigations into the relationship between changes in internal moisture regimes and rock surface deterioration in cavernous sandstone features cavernous features commonly develop in sandstone but their development over time remains enigmatic it has been suggested that moisture movements within the rock mass play a key role in the location development and dynamics of cavernous features in this research the role of internal moisture movement is tested through monitoring moisture and surface deterioration dynamics in april 2008 and april 2009 within two large cavernous features mega tafoni in the golden gate highlands national park south africa gghnp data are presented from surveys of internal moisture using electrical resistivity tomography ert surface moisture using a protimeter and deterioration using surface hardness as recorded with an equotip as a proxy for surface deterioration across five 2 45 m long transects in addition a high resolution temperature record is presented to assess the influence of micro climates within the caverns the results indicate consistency in the gross spatial pattern of moisture flow within the rock mass over a one year period but significant changes in mean moisture contents and in the fine detail of moisture patterning some noticeably weakened areas had developed within the central parts of the cavernous features often linked to wetter subsurface conditions supporting the theory that core softening is a main driver of cavernous feature formation however in some areas surface hardening is also found to be associated with wetter subsurface conditions supporting the theory that case hardening is a main driver of cavernous feature formation in addition the presence of well established biofilms suggests an even more complex interaction between moisture surface development and biological activity a model is presented therefore which integrates this paradox by proposing a non linear relationship between moisture dynamics facilitation of biofilm formation and deterioration within cavernous features

centrifuge model simulations of rainfall induced slope instability abstractthis study focused on landslides resulting from heavy precipitation such as rainfall from hurricanes a series of centrifuge model simulations were performed with reference to a landslide that occurred during typhoon nabi in japan in 2005 the procedures of simulation on the slope using a sand clay soil mixture were illustrated the rainfall event was simulated by applying precipitation in increments to the slope surface until it exceeded that of the field measurements the instability was examined using an infinite slope analysis and the mechanism of rainfall induced failure was discussed for this particular study the results showed that incremental rainfall of less than 200 mm led to local failures whereas total accumulation of 400 mm resulted in a global slope failure a reduction in apparent cohesion in the soil combined with an increase in pore pressure because of infiltration was responsible for the slope instability during rainfall

deformation failure mechanism of saturated fill slopes due to resonance phenomena based on 1g shaking table tests earthquake motions include waves of various frequency bands ranging from low to high frequency notably the dominant frequency affects the seismic stability of fill slopes hence to analyze the d

dynamic stability analysis of jointed rock slopes using the dda method king herod s palace masada israel abstract a dynamic two dimensional stability analysis of a highly discontinuous rock slope is demonstrated in this paper the studied rock slope is the upper terrace of king herod s palace in masada situated on the western margins of the seismically active dead sea rift the slope consists of sub horizontally bedded and sub vertically jointed stiff dolomite blocks the dynamic deformation of the slope is calculated using a fully dynamic version of dda in which time dependent acceleration is used as input the analytically determined failure modes of critical keyblocks in the jointed rock slope are clearly predicted by dda at the end of the dynamic calculation it is found however that for realistic displacement estimates some amount of energy dissipation must be introduced into the otherwise fully elastic un damped dda formulation comparison of predicted damage with actual slope performance over a historic time span of 2000 years allows us to conclude that introduction of 2 kinetic damping should suffice for realistic damage predictions this conclusion is in agreement with recent results of tsesarsky et al in y h hatzor ed stability of rock structures proceedings of the fifth international conference of analysis of discontinuous deformation balkema publishers lisse 2002 pp 195 203 who compared displacements of a single block on an inclined plane subjected to dynamic loading obtained by dda and by shaking table experiments using dynamic dda it is shown that introduction of a simple rock bolting pattern completely stabilizes the slope

shoreline reconstructions for the persian gulf since the last glacial maximum abstract sea level change in the persian gulf since the time of the last maximum glaciation at about 18 000 yr bp is predicted to exhibit considerable spatial variability because of the response of the earth to glacial unloading of the distant ice sheets and to the meltwater loading of the gulf itself and the adjacent ocean models for these glacio hydro isostatic effects have been compared with observations of sea level change and palaeoshoreline reconstructions of the gulf have been made from the peak of the glaciation until about 14 000 yr bp the gulf is free of marine influence out to the edge of the biaban shelf by 14 000 yr bp the strait of hormuz had opened up as a narrow waterway and by about 12 500 years ago the marine incursion into the central basin had started the western basin flooded about 1000 years later momentary stillstands may have occurred during the gulf flooding phase at about 11 300 and 10 500 yr bp the present shorelines was reached shortly before 6000 yr ago and exceeded as relative sea level rose 1 2 m above its present level inundating the low lying areas of lower mesopotamia these reconstructions have implications for models of the evolution of the euphrates tigris karun delta as well as for the movements of people and the timing of the earliest settlements in lower mesopotamia for example the early gulf floor would have provided a natural route for people moving westwards from regions to the east of iran from the late palaeolithic to early neolithic

alkane terpene and polycyclic aromatic hydrocarbon geochemistry of the mackenzie river and mackenzie shelf riverine contributions to beaufort sea coastal sediment abstract to study the largest source of river sediment to the arctic ocean we have collected suspended particulates from the mackenzie river in all seasons and sediments from the mackenzie shelf between the river mouth and the shelf edge these samples have been analyzed for alkanes triterpenes and polycyclic aromatic hydrocarbons pahs we found that naturally occurring hydrocarbons predominate in the river and on the shelf these hydrocarbons include biogenic alkanes and triterpenes with a higher plant peat origin diagenetic pahs from peat and plant detritus petrogenic alkanes triterpenes and pahs from oil seeps and or bitumens and combustion pahs that are likely relict in peat deposits because these components vary independently the season is found to strongly influence the concentration and composition of hydrocarbons in the mackenzie river while essentially the same pattern of alkanes diagenetic hopanes and alkyl pahs is observed in all river and most shelf sediment samples alkane and triterpene concentration variations are strongly linked to the relative amount of higher plant peat material polycyclic aromatic hydrocarbon molecular mass profiles also appear to be tied primarily to varying proportions of peat with an additional petrogenic component which is most likely associated with lithic material mobilized by the mackenzie river at freshet consistent with the general lack of alkyl pahs in peat the higher pahs found in the river are probably derived from forest and tundra fires a few anthropogenic pyrogenic compounds are manifest only at the shelf edge probably due to a weakening of the river influence we take this observation of pyrogenic pahs and the pronounced source differences between two sediment samples collected at the shelf edge as evidence of a transition from dominance by the mackenzie river to the geochemistry prevalent in arctic regions far removed from major rivers

study on a failed dip slope with a thin sandy layer in 2004 niigata ken chuetsu earthquake among the extensive failed slopes in the 2004 niigata ken chuetsu earthquake japan a dip slope at yokowatashi ojiya was investigated intensively the sliding plane was along a weak thin tuff sandy layer which had been deeply weathered triaxial compression tests and plane strain compression tests were performed on undisturbed specimens obtained by block sampling and boring sampling to evaluate the strength that was mobilized on the sliding plane stability analysis based on the test results reveals that at normal time without earthquake and without an extremely high groundwater level the slope is stable furthermore the calculation of earthquake induced displacement provides a reasonable simulation of the failure of this slope

large deformation finite element modelling of earthquake induced landslides considering strain softening behaviour of sensitive clay large scale landslides in sensitive clays cannot be explained properly using the traditional limit equilibrium or lagrangian based finite element fe methods in the present study dynamic fe anal

a multi block sliding approach to calculate the permanent seismic displacement of slopes abstract the newmark sliding block method is widely used to assess the seismic performance of earth slopes by calculating the permanent displacement of the simplified sliding mass the conventional newmark method models the potential landslide mass as a single rigid block sliding on a well defined slip surface in this study a multi block approach to calculate the sliding displacement of slopes is presented the dynamic equation of a series of rigid blocks in different sliding conditions is established and the complex interactions within the slip episodes of rigid block assemblies are explicitly resolved the results show that the original newmark single block method may produce unconservative estimates of permanent displacement of the shallow sliding mass when the deep seated sliding subsequently occurs during the earthquake the predicted displacement of the upper sliding mass which is simplified as a summation of the newmark displacement of each single sliding mass may either overestimate or underestimate the computed displacement including the coupling of sliding of multiple soil masses the developed approach extends the well accepted newmark sliding block method and can serve as an alternative to predict the seismic slope displacement in which multiple failure surfaces are expected during earthquakes

inclined plane studies of the newmark sliding block procedure this study considers the shaking induced displacement and dynamic response of a rigid block and deformable columns of soil on an inclined plane this work demonstrates that because of the coupled d

coupled analysis of earthquake induced permanent deformations at shallow and deep failure planes of slopes abstract the seismic performance of slopes is commonly evaluated by simplified sliding block analyses in this paper an extended sliding block model is developed to compute the earthquake induced deformations at both shallow and deep failure planes of slopes the coupled analytical model captures simultaneously the stick stick stick slip and slip slip behaviors of the lumped mass system of soil profile the complex interactions between the dynamic response of the soil and the slip episodes at shallow and deep slide planes are revealed the proposed sliding model is compared to the conventional single base sliding analyses and the influence of the presence of shallow failure sliding is emphasized then the dynamic response and permanent displacement of slopes with different locations of the shallow sliding plane and different yield accelerations of shallow and deep sliding planes are examined the comparisons are also performed for permanent displacements determined from the developed coupled multi sliding procedure and from the seismic sliding model with multiple rigid blocks finally an example is presented to demonstrate the procedure in the application and the differences of the results from the traditional coupled approach the coupled model in this study provides a rigorous procedure to combine the shallow and deep failure modes for the assessment of the co seismic landslide hazard

early diagenesis of trace metals used as an indicator of past productivity changes in coastal sediments in sediments of kiel bight which differ significantly in their redox states and the rates of corg degradation depth profiles of both dissolved and solid phase fe mn cd cu ni and co were measured porewater fluxes of cd cu and ni were significantly higher at shallower more oxic stations as compared to highly reducing deeper subthermocline sediments while mn fluxes behaved the opposite way when normalized to fe for grain size correction the measured solid phase metal contents revealed that the high porewater flux has led to a near surface depletion of mn from more anoxic sediments and to a reduced rate of accumulation of anthropogenic cd in more oxic sediments this difference in early diagenetic behaviour suggests the use of these metals as a proxy for the redox state and the intensity of carbon recycling contrary to the recent sediment layers the normalized metal contents of preindustrially deposited sediment layers were similar for both metals at all stations thus at stations having highly anoxic sediments today the preindustrial benthic flux must have been lower for mn and higher for cd reflecting a shift from more oxic to more reducing conditions in subthermocline sediments during the last 100 years this change of the redox state in subthermocline sediments reflects an increase of primary production and of subsequent corg input to the sediment due to eutrophication which accompanied industrialization

can tilt tests provide correct insight regarding frictional behavior of sliding rock block under seismic excitation earthquake induced dip slope sliding or rock block sliding is usually analyzed using friction angles or friction coefficients measured at the sliding interface a tilt test is a convenient test for measuring the required friction angle however a tilt test is a test under static conditions and the applicability of measured friction parameters to analyze slopes under dynamic excitation requires further discussion this study conducts a static tilt test and a dynamic shaking table test to simulate block sliding with base excitation compares differences in measured sliding thresholds and discusses the cause of these differences tests on three different materials aluminum sandstone and synthetic sandstone show that friction coefficients measured by tilt tests are always larger than the ones derived by shaking table tests moreover high frequency tests yield larger friction coefficients suggesting the sliding threshold is non constant under excitation in addition tests with varying normal stresses on the sliding block show that with increasing contact stresses sliding thresholds decrease implying that sliding threshold varies with normal stress instantaneous friction coefficients i t during sliding are also studied in this work it has been found that frictional behavior of synthetic sandstone deviates from the idealized coulomb friction model the instantaneous friction coefficient varies with relative displacement and relative velocity during sliding finally reasons for differences between a static tilt test and a dynamic shaking table test are discussed this study preliminarily identifies the limitations of the tilt test when applied to dynamic problems and concludes that realistic sliding thresholds can only be obtained using dynamic tests such as shaking table tests