earthquake induced landslide susceptibility mapping using an integrated ensemble frequency ratio and logistic regression models in west sumatera province indonesia an 8 richter scale rs earthquake struck west sumatra on wednesday 30 september 2009 at 17 16 pm which led to huge number of landslides hence a comprehensive landslide susceptibility mapping lsm should be produced in order to reduce the damages to people and infrastructures in the international landslide literature various statistical methods such as frequency ratio fr and logistic regression lr have been widely used individually for lsm but they have some weaknesses fr which is able to perform bivariate statistical analysis bsa assesses the influence of classes of each conditioning factor on landslide occurrence however the correlation between the factors is mostly neglected on the other hand lr is able to analyze the relationship among the factors while it is not capable to evaluate the classes of each landslide conditioning factor this paper aims to propose an ensemble method of fr and lr in order to overcome their weak points for lsm a landslide inventory map with a total of 87 landslide locations was extracted from various sources then the landslide inventory was randomly divided into two datasets 70 for training the models and the remaining 30 was used for validation purpose the landslide conditioning factors consist of altitude curvature river spi rainfall soil type soil texture land use cover lulc peak ground acceleration pga geology slope aspect lineament and topographic wetness index twi four pga of 7 5 8 8 6 and 9 were acquired and pga 8 which was related to the 2009 earthquake was used to generate the model finally the produced landslide susceptibility maps were validated using an area under the roc curve method for the model which was derived by pga 8 the validation results showed 84 and 78 success and prediction rates respectively furthermore the prediction rates for the models made by pga 7 2 8 6 and 9 are 79 78 and 81 respectively the result proved the reasonable efficiency of the proposed method for earthquake induced landslide susceptibility mapping also the proposed ensemble method can be used in other hazard studies as it is capable to produce rapid and accurate assessment for disaster management and decision making

balancing rare earth element distributions in the northwestern mediterranean sea abstract elemental concentrations of rare earth elements ree and isotopic compositions of neodymium end have been measured in three water column profiles in the north western mediterranean sea clear enrichments of ree are observed when comparing to adjacent atlantic waters suggesting ree inputs along the circulation in this area for the first time relative proportions of external sources including submarine groundwater discharges sgd have been quantified for the studied area atmospheric deposition is estimated to be the most important external source for all the ree with an average contribution of 44 followed by diffusion from porewaters which provide a 30 dissolved riverine fluxes account for 11 sgd for 10 and dissolution of remobilized surface sediments the remaining 6 mass balances accounting for seawater transport and identified external sources have been delineated for the three main water masses modified atlantic waters levantine intermediate waters and western mediterranean deep waters they show that the balances of ree in this area are dominated by seawater mass mixing superimposed on this hydrography ree vertical profiles are affected by external sources and biogeochemical cycling dissolved ree are correctly balanced in deep waters whereas substantial missing fluxes are identified in the surface and intermediate water masses additional net lree outputs and hree inputs are required in the surface waters while net output fluxes for all the ree are missing at intermediate waters the most likely process suggested here is an active reversible scavenging consistent with a stronger adsorption of lree compared to hree in the particular case of the redox sensitive cerium the most plausible mechanism to explain the net output missing fluxes is ce 3 removal by particle scavenging via oxidation to insoluble ce 4 estimated ce oxidation rates of 0 33 d 1 in surface waters agree well with previously published values exchange fluxes derived from the isotopic nd mass balance indicate higher nd scavenging in surface compared to intermediate waters

landslides triggered by the 22 july 2013 minxian zhangxian china mw 5 9 earthquake inventory compiling and spatial distribution analysis abstract on july 22 2013 an earthquake of ms 6 6 occurred at the junction area of minxian and zhangxian counties gansu province china this earthquake triggered many landslides of various types dominated by small scale soil falls slides and topples on loess scarps there were also a few deep seated landslides large scale soil avalanches and fissure developing slopes in this paper an inventory of landslides triggered by this event is prepared based on field investigations and visual interpretation of high resolution satellite images the spatial distribution of the landslides is then analyzed the inventory indicates that at least 2330 landslides were triggered by the earthquake a correlation statistics of the landslides with topographic geologic and earthquake factors is performed based on the gis platform the results show that the largest number of landslides and the highest landslide density are at 2400 m 2600 m of absolute elevation and 200 m 300 m of relative elevation respectively the landslide density does not always increase with slope gradient as previously suggested the slopes most prone to landslides are in s sw w and nw directions concave slopes register higher landslide density and larger number of landslides than convex slopes the largest number of landslides occurs on topographic position with middle slopes whereas the highest landslide density corresponds to valleys and lower slopes the underlying bedrocks consisting of conglomerate and sandstone of lower paleogene eb register both the largest number and area of landslides and the highest landslide number and area density values correlations of landslide number and landslide density with perpendicular and along strike distance from the epicenter show an obvious spatial intensifying character of the co seismic landslides the spatial pattern of the co seismic landslides is strongly controlled by a branch of the lintan dangchang fault which indicates the effect of seismogenic fault on co seismic landslides in addition the area affected by landslides related to the earthquake is compared to the relationship of area affected by landslides vs earthquake magnitude constructed based on earthquakes worldwide and it is shown that the area affected by landslides triggered by the minxian zhangxian earthquake is larger than that of almost all other events with similar magnitudes

exchange of neodymium and its isotopes between seawater and small and large particles in the sargasso sea the concentrations and isotopic ratios of nd were measured in small 1 53 m and large 53 m in situ filtered particles sediment trap material sediment and aerosol samples collected during oligotrophic and productive conditions in the sargasso sea atmospheric input is the main source of exogeneous nd into the sargasso sea based on ndal ratios in trapped material we suggest that up to 50 of atmospheric nd could dissolve at the air sea interface the concentration and isotopic composition of nd vary with both depth and the particle size neodymium concentrations of small and large particles increase with depth from 2 9 12 g g and 5 8 11 8 g g respectively at 40 m the nd signature of large particles is significantly more negative nd 0 13 1 0 2 than that of the small ones nd 0 11 7 0 3 and the particles filtered deeper below 237 m the nd 0 values for small particles match the seawater whereas the nd 0 values of large particles remain less radiogenic these differences are related to the different behaviors of the particulate fractions small particles apparently exchange nd with seawater and then sink rapidly to depth as biologically formed aggregates large particles these aggregates isolate the small particles slowing the exchange with the water to produce different signatures between large particles and seawater since these exchange processes modify the particulate nd signature the shallow radiogenic nd 0 signature observed in the surface and subsurface waters in the nw atlantic is not due to external contributions and is likely of advective origin at depth below 800 m the magnitude of the aggregation disaggregation process varies significantly with season the fraction of small particles repackaged into large aggregates can vary from 0 8 to 80 100 in productive and oligotrophic conditions respectively this seasonal variation may correspond to sinking particles of different zooplanktonic origin vertical fluxes of nd into and out of the sargasso sea as well as exchange fluxes in the water column are examined about 50 of the particulate flux from the surface is remineralized at depth a net scavenging flux of 0 8 10 4 g m2 y is required this value corresponds to a scavenging nd residence time of 1900 y considerably longer than previous estimates of global oceanic residence time of nd on the order of 400 y

why so few landslides triggered by the 2002 denali earthquake alaska abstract the 2002 m w 7 9 denali fault earthquake alaska provides an unparalleled opportunity to investigate in quantitative detail the regional hillslope mass wasting response to strong seismic shaking in glacierized terrain we present the first detailed inventory of 1580 coseismic slope failures out of which some 20 occurred above large valley glaciers based on mapping from multi temporal remote sensing data we find that the denali earthquake produced at least one order of magnitude fewer landslides in a much narrower corridor along the fault ruptures than empirical predictions for an m 8 earthquake would suggest despite the availability of sufficiently steep and dissected mountainous topography prone to frequent slope failure in order to explore potential controls on the reduced extent of regional coseismic landsliding we compare our data with inventories that we compiled for two recent earthquakes in periglacial and formerly glaciated terrain i e at yushu tibet m w 6 9 2010 and aysen fjord chile 2007 m w 6 2 fault movement during these events was similarly to that of the denali earthquake dominated by strike slip offsets along near vertical faults our comparison returns very similar coseismic landslide patterns that are consistent with the idea that fault type geometry and dynamic rupture process rather than widespread glacier cover were among the first order controls on regional hillslope erosional response in these earthquakes we conclude that estimating the amount of coseismic hillslope sediment input to the sediment cascade from earthquake magnitude alone remains highly problematic particularly if glacierized terrain is involved

231pa 230th fractionation by ocean transport biogenic particle flux and particle type 231pa and 230th are removed from the water column by a process of reversible scavenging which quickly removes 230th to the sediment 231pa is less efficiently scavenged onto particles than 230th and is therefore more effectively transported via advection and diffusion before it reaches the ocean sediment this study combines particle fields dust opal caco3 poc derived from observations with the bern3d intermediate complexity ocean model and an equilibrium scavenging model for isotopes the equilibrium partition coefficient for particulate versus dissolved isotope activity is varied with particle type the model can explain many of the features of the global 231pa and 230th distribution the success of such a simple model at representing the global pattern of 231pa 230th activity ratio supports the use of this proxy in paleoceanographic studies we use the model to address the controversy concerning which particle types are dominant in fractionating 231pa 230th in the ocean the lithogenic dust flux is found to be unimportant for 231pa 230th fractionation the ocean fractionation of 231pa 230th is dominated by the distribution of the caco3 and opal flux we also confirm that opal is a weak scavenger of 230th

the large scale evolution of neodymium isotopic composition in the global modern and holocene ocean revealed from seawater and archive data neodymium isotopic compositions 143nd 144nd or end have been used as a tracer of water masses and lithogenic inputs to the ocean to further evaluate the faithfulness of this tracer we have updated a global seawater end database and combined it with hydrography parameters temperature salinity nutrients and oxygen concentrations carbon isotopic ratio and radiocarbon of dissolved inorganic carbon archive end data are also compiled for leachates foraminiferal tests deep sea corals and fish teeth debris from the holocene period 10 000 years at water depths 1500 m property property plots show clear correlations between seawater end and the other variables suggesting that large scale water mass mixing is a primary control of deepwater end distribution at 200 m basin scale seawater t s end diagrams demonstrate the isotopic evolution of different water masses seawater and archive end values are compared using property property plots and t s end diagrams archive values generally agree with corresponding seawater values although they tend to be at the upper limit in the pacific both positive and negative offsets exist in the northern north atlantic applying multiple regression analysis to deep 1500 m seawater data we established empirical equations that predict the main large scale deepwater end trends from hydrography parameters large offsets from the predicted values are interpreted as a sign of significant local regional influence dominant continental influence on seawater and archive end is observed mainly within 1000 km from the continents generally seawater and archive end values form gradual latitudinal trend in the atlantic and pacific at depths 600 m consistent with the idea that nd isotopes help distinguish between northern southern sourced water contributions at intermediate and deep water depths

tracing past ocean circulation to understand how ocean circulation and climate may change in the future we must first understand how the system operated in the past without man9s influence new inorganic isotopic tracers are now helping to elucidate past ocean circulation patterns but controversies remain regarding the relative influence of ocean circulation and weathering on the isotopic signals

mechanics of the earthquake induced hongshiyan landslide in the 2014 mw 6 2 ludian earthquake yunnan china abstract the hongshiyan landslide the largest landslide volume 12 24 mm3 triggered by 2014 mw 6 2 ludian earthquake blocked the niulan river forming a rockslide dam the failure potential of the dam created an elevated risk to population and infrastructure downstream we provide insight into the failure mechanics of the hongshiyan landslide using data obtained by means of remote sensing techniques and traditional in situ surveys geological data obtained by these methods was then used for kinematic and numerical analyses our study shows that failure of the hongshiyan landslide involved a high rock slope with an average slope of 55 and aspect of 185 ssw in which the geological setting consists of an upper strong limestone slab and an underlying weak silty mudstone the geological setting allowed the landslide to develop as follows i the silty mudstone due to its poor mechanical properties was subject to ductile deformation under the compressive loading from the overlying strong limestone slabs ii a large number of release fractures in the limestone developed as a consequence of pre failure progressive deformation in the underlying weak mudstone iii the oxidation and solution along steep joint walls in the upper limestone indicates that the joints are pathways that allow water ingress into the mudstone further promoting the degradation of shear strength in this layer distinct element modelling udec was used to back analyse the failure mechanism and develop the geological model that best reproduced the hongshiyan failure geometry results show that the failure surface consisted of two elements the upper steeply dipping release surface formed along the slope parallel steep cross joints defining a jointed strong limestone slab and the toe of the failure formed a curved failure surface through the ductile weak silty mudstone underlying the limestone slab independent of any discontinuities within it the pre failure observations and numerical analysis suggest that the hongshiyan slope was in a state of marginal static stability prior to the earthquake as a result of pre failure progressive deformation controlled by the shear strength of the underlying mudstone overall the marginal pre earthquake stability of the hongshiyan slope coupled with the strongest seismic loading which the hongshiyan slope has been historically subjected to are the reasons why this moderate earthquake induced a large scale catastrophic rock slope failure

near real time modelling of landslide impacts to inform rapid response an example from the 2016 kaikōura new zealand earthquake reliable methods for the near real time modeling of landslide hazard and associated impacts that follow an earthquake are required to provide crucial information to guide emergency responses after the 2016 kaikoura earthquake in new zealand we undertook such a near real time modeling campaign in an attempt to pinpoint the location of landslides and identify the locations where roads and rivers had been blocked the model combined an empirical analysis of landslide hazard based on previously published global relationships with a simple runout model based on landslide reach angles it was applied manually with a first iteration completed within 24 hrs of the earthquake and a second iteration based on updated shaking outputs within 72 hrs both models highlighted the expectation that landsliding would be widespread and that impacts to roads likely meant that the township of kaikoura was cut off from the surroundings these results were used by responders at the time to formulate aerial reconnaissance flight paths and to identify the risk that landslide dams could cause further damage subsequent model verification based on available landslide inventories shows that although these models were able to capture a large percentage of landslides and landslide impacts the outputs were overpredicted limiting their use for pinpointing the precise locations of triggered landslides to make future versions of the model more useful for informing emergency responses continued work must be done on modification and adaptation of the approach so that this overprediction is minimized nevertheless the results from this study show that the model is a promising initial attempt at near real time landslide modeling and that efforts to automate the approach would greatly increase the utility and speed of modeling in future earthquakes

application and evaluation of a rapid response earthquake triggered landslide model to the 25 april 2015 mw 7 8 gorkha earthquake nepal abstract the 25 april 2015 m w 7 8 gorkha earthquake produced strong ground motions across an approximately 250 km by 100 km swath in central nepal to assist disaster response activities we modified an existing earthquake triggered landslide model based on a newmark sliding block analysis to estimate the extent and intensity of landsliding and landslide dam hazard landslide hazard maps were produced using shuttle radar topography mission srtm digital topography peak ground acceleration pga information from the u s geological survey usgs shakemap program and assumptions about the regional rock strength based on end member values from previous studies the instrumental record of seismicity in nepal is poor so pga estimates were based on empirical ground motion prediction equations gmpes constrained by teleseismic data and felt reports we demonstrate a non linear dependence of modeled landsliding on aggregate rock strength where the number of landslides decreases exponentially with increasing rock strength model estimates are less sensitive to pga at steep slopes 60 compared to moderate slopes 30 60 we compare forward model results to an inventory of landslides triggered by the gorkha earthquake we show that moderate rock strength inputs over estimate landsliding in regions beyond the main slip patch which may in part be related to poorly constrained pga estimates for this event at far distances from the source area directly above the main slip patch however the moderate strength model accurately estimates the total number of landslides within the resolution of the model landslides 0 0162 km 2 observed n 2214 modeled n 2987 but the pattern of landsliding differs from observations this discrepancy is likely due to the unaccounted for effects of variable material strength and local topographic amplification of strong ground motion as well as other simplifying assumptions about source characteristics and their relationship to landsliding

a new approach to the nd residence time in the ocean the role of atmospheric inputs concentrations of rare earth elements ree and nd isotopic ratios were analyzed for seawater filtered suspension and sediment trap samples collected in the tropical atlantic ocean eumeli program eutrophic mesotrophic and oligotrophic sites 20 n 18 21 w this is the first ree nd dataset on solution and different sized particles collected at the same site we present direct evidence of the nd isotopic exchange between particulate lithogenic fraction and seawater without significant mass transfer this exchange is probably one of the main factors that simultaneously constrains the nd concentration and isotopic ratio budget we propose a new approach to estimate the residence time of nd in the ocean nd based on isotopic exchange 200 yr nd 1000 yr the exchange requires a partial dissolution of lithogenic nd we estimate that the fraction of soluble nd proportion in atmospheric dust is of the order of 20 based on the isotopic ratios we suggest that the partial dissolution of atmospheric fallout is probably one of the main ree sources of the ocean

effects of sampling intensity and non slide slide sample ratio on the occurrence probability of coseismic landslides abstract due to the influence of sampling strategy the resulting probability of landslides using logistic regression lr can deviate considerably from the actual areal percentage of coseismic landslides this study used the landslides data of the 2013 lushan china earthquake to further address this issue based on the bayesian theory we proposed a sampling method that selects the sliding samples and non sliding samples based on the ratio of the stable area to the landslide area using this method we tested 15 values of sampling intensities 1 10 20 30 40 50 60 70 80 90 100 200 500 1000 and 2000 grid cell km 2 and 12 values of non sliding sliding sample ratios 1 5 10 25 50 75 100 125 150 175 200 and 228 for the analysis of the lr model ten factors were considered in this analysis including elevation slope gradient aspect the topographic wetness index twi peak ground acceleration pga distance to the epicenter distance to rivers distance to roads lithology and annual precipitation in terms of these 15 sampling intensities and 12 sample ratios the samples were trained 200 and 150 times respectively using the lr model yielding 4800 predicted pictures of potential landslides in the study area the results show that different sampling intensities have a certain effect on the total predicted landslide area the higher the intensity of the samples the more stable the prediction results especially when the sampling intensity reaches 1000 grid cell km 2 the total area of the predictive model is about 17 1 km2 which is close to the real area with 17 16 km2 with a difference within 2 different ratios of non slide slide sample greatly affect the occurrence probability of coseismic landslides when the ratio is 1 1 the predicted landslide area ap is between 1265 and 1290 km2 with an average of 1280 km2 which is 75 times the actual landslide area the functional relationship between the ratio of predicted area to real area rpa and the ratio of non sliding samples to sliding samples rns is r pa 99 156 r ns 0 826 it implies that the non slide slide sample ratio determined by the ratio of stable area to the landslide area permits us to construct real probability models to predict the areal percentages of landslides and based on such models the predicted probability is largely consistent with the actual areal percentage of coseismic landslides

variation in landslide affected area under the control of ground motion and topography abstract earthquake induced landslide eqil inventories are the key to improve our understanding of the relationship between landslides and their causes including environmental settings and ground shaking parameters however creating a high quality inventory can take years as a result reliable information on landslide affected areas typically remains unknown until a complete inventory is compiled in this paper we analyze 20 digital eqil inventories of varying quality and completeness that represent a range of geologic and climatic settings around the globe we examine the landslide affected area with respect to peak ground acceleration pga and topography and develop a statistical model to estimate the landslide distribution without prior knowledge of the actual landslide triggering locations for each eqil inventory we initially calculated the pga contours where 90 of the total landslide population fell into subsequently we define landslide susceptible areas as those pixels with slope 5 and local relief 100 m the latter is used to normalize the total landslide affected area and to compute correlations with local pga values we find that the landslide affected area may be predicted from pga values only with the mean error ranging from 20 0 to 7 1 with respect to total landslide population this relationship can be used immediately following a disaster to identify areas of greatest landslide impact and to prioritize emergency response actions even without a landslide inventory

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

development of a globally applicable model for near real time prediction of seismically induced landslides substantial effort has been invested to understand where seismically induced landslides may occur in the future as they are a costly and frequently fatal threat in mountainous regions the goal of this work is to develop a statistical model for estimating the spatial distribution of landslides in near real time around the globe for use in conjunction with the u s geological survey usgs prompt assessment of global earthquakes for response pager system this model uses standardized outputs of ground shaking from the usgs shakemap atlas 2 0 to develop an empirical landslide probability model combining shaking estimates with broadly available landslide susceptibility proxies i e topographic slope surface geology and climate parameters we focus on four earthquakes for which digitally mapped landslide inventories and well constrained shakemaps are available the resulting database is used to build a predictive model of the probability of landslide occurrence the landslide database includes the guatemala 1976 northridge 1994 chi chi 1999 and wenchuan 2008 earthquakes performance of the regression model is assessed using statistical goodness of fit metrics and a qualitative review to determine which combination of the proxies provides both the optimum prediction of landslide affected areas and minimizes the false alarms in non landslide zones combined with near real time shakemaps these models can be used to make generalized predictions of whether or not landslides are likely to occur and if so where for earthquakes around the globe and eventually to inform loss estimates within the framework of the pager system

relation of landslides triggered by the kiholo bay earthquake to modeled ground motion abstract the 2006 kiholo bay hawaii earthquake triggered high concentrations of rock falls and slides in the steep canyons of the kohala mountains along the north coast of hawaii within these mountains and canyons a complex distribution of landslides was triggered by the earthquake shaking in parts of the area landslides were preferentially located on east facing slopes whereas in other parts of the canyons no systematic pattern prevailed with respect to slope aspect or vertical position on the slopes the geology within the canyons is homogeneous so we hypothesize that the variable landslide distribution is the result of localized variation in ground shaking therefore we used a state of the art high resolution ground motion simulation model to see if it could reproduce the landslide distribution patterns we used a 3d finite element analysis to model earthquake shaking using a 10 m digital elevation model and slip on a finite fault model constructed from teleseismic records of the mainshock ground velocity time histories were calculated up to a frequency of 5 hz dynamic shear strain also was calculated and compared with the landslide distribution results were mixed for the velocity simulations with some areas showing correlation of landslide locations with peak modeled ground motions but many other areas showing no such correlation results were much improved for the comparison with dynamic shear strain this suggests that 1 rock falls and slides are possibly triggered by higher frequency ground motions velocities than those in our simulations 2 the ground motion velocity model needs more refinement or 3 dynamic shear strain may be a more fundamental measurement of the decoupling process of slope materials during seismic shaking

regional coseismic landslide hazard assessment without historical landslide inventories a new approach currently regional coseismic landslide hazard analyses require comprehensive historical landslide inventories as well as detailed geotechnical data consequently such analyses have not been possible where these data are not available a new approach is proposed herein to assess coseismic landslide hazard at regional scale for specific earthquake scenarios in areas without historical landslide inventories the proposed model employs fuzzy logic and geographic information systems to establish relationships between causative factors and coseismic slope failures in regions with well documented and substantially complete coseismic landslide inventories these relationships are then utilized to estimate the relative probability of landslide occurrence in regions with neither historical landslide inventories nor detailed geotechnical data statistical analyses of inventories from the 1994 northridge and 2008 wenchuan earthquakes reveal that shaking intensity topography and distance from active faults and streams are the main controls on the spatial distribution of coseismic landslides average fuzzy memberships for each factor are developed and aggregated to model the relative coseismic landslide hazard for both earthquakes the predictive capabilities of the models are assessed and show good to excellent model performance for both events these memberships are then applied to the 1999 chi chi earthquake using only a digital elevation model active fault map and isoseismal data replicating prediction of a future event in a region lacking historic inventories and or geotechnical data this similarly results in excellent model performance demonstrating the model s predictive potential and confirming it can be meaningfully applied in regions where previous methods could not for such regions this method may enable a greater ability to analyze coseismic landslide hazard from specific earthquake scenarios allowing for mitigation measures and emergency response plans to be better informed of earthquake related hazards

digital terrain modelling a review of hydrological geomorphological and biological applications the topography of a catchment has a major impact on the hydrological geomorphological and biological processes active in the landscape the spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques many geographic information systems are being developed that store topographic information as the primary data for analysing water resource and biological problems furthermore topography can be used to develop more physically realistic structures for hydrologic and water quality models that directly account for the impact of topography on the hydrology digital elevation models are the primary data used in the analysis of catchment topography we describe elevation data sources digital elevation model structures and the analysis of digital elevation data for hydrological geomorphological and biological applications some hydrologic models that make use of digital representations of topography are also considered

database and spatial distribution of landslides triggered by the lushan china mw 6 6 earthquake of 20 april 2013 abstract on 20 april 2013 an earthquake with mw 6 6 ms 7 0 hit lushan county sichuan province of china 30 3 n 103 e only 85 km southwest of the 2008 wenchuan mw 7 9 event the lushan shock triggered a large number of landslides with various types including highly disrupted shallow slides and rock falls deep seated landslides and large scale rock avalanches post earthquake high resolution aerial photographs and satellite images as well as a series of pre earthquake high resolution satellite images were collected to construct a detailed accurate objective and complete coseismic landslide database inventory which was validated by field investigation in selected areas based on the aerial photographs 0 2 or 0 6 m resolution that partly cover the affected area and pre earthquake satellite images 14 580 coseismic landslides were recognized and mapped in those areas without post earthquake aerial photographs coverage we mapped 7 948 more coseismic landslides based on post earthquake satellite images rapideye images with 5 m resolution and zy 3 images including panchromatic images with 2 1 m resolution and multi spectral images with 5 8 m resolution and pre earthquake satellite images the 22 528 coseismic landslides with a horizontal projection area of 18 88 km 2 and an estimated total volume of 41 56 10 6 m 3 were distributed in a nearly elliptic area of about 5 400 km 2 correlations between coseismic landslide abundances and topographic geologic and seismic factors were analyzed on 15 546 landslides of area 100 m 2 scatter plots between regional slope angle and landslide abundances in generalized homogeneous lithology combinations show no obvious relationship is present between them which challenges the conclusions of previous studies combining the lushan earthquake triggered landslides with other events on reverse and or thrust faults such as the 1999 chi chi and 2008 wenchuan shocks we found that coseismic landslides tend to occur in areas enveloped by two or more imbricated reverse and or thrust faults rather than only along the seismogenic fault the lushan event shows a higher ability of triggering landslides compared with other earthquakes of similar magnitudes which is likely due to the steep and rugged topography and fractured and densely jointed lithology resulted from long term tectonic activity the blind reverse seismogenic fault is likely also another significant factor based on detailed coseismic landslide inventory maps and databases of several recent major earthquakes such as the 2008 wenchuan 2010 haiti 2010 yushu and 2013 lushan temblors we suggest that the empirical correlations between earthquake magnitude and coseismic landslides need to be updated

neodymium isotopic variations in northwest pacific waters abstract four vertical profiles of the concentration and isotopic composition of nd in seawater were obtained in the western north pacific two profiles from the kuroshio current regime showed congruently that although the nd concentration increases gradually with depth its isotopic composition varies significantly with depth depending upon the water mass occupying the water column the high salinity kuroshio waters originating from the north pacific tropical water nptw carry the least radiogenic nd nd 7 4 to 8 7 to this region at 250 m from the western margin continental shelves most likely from the east china sea the nd isotopic compositions in the north pacific intermediate water npiw that occurs at 600 to 1000 m in the subtropical region are fairly uniform at nd 3 7 the profile data from the 38 to 40 n kuroshio oyashio mixed water region off sanriku of honshu japan also suggest that the newest npiw with nd 3 2 is formed there by the mixing of various source waters and the radiogenic component of nd is derived mainly from the oyashio waters in the pacific deep water pdw below 1000 m the nd isotopic composition is neither vertically nor horizontally homogeneous suggesting that it serves as a useful tracer for sluggish deep water circulation as well two profiles from the izu ogasawara trench showed a minimum nd value at 2000 m suggesting that there exists a horizontal advective flow in the vicinity of honshu japan there is some evidence from other chemical properties to support this observation the waters below 4000 m including those within the trench in the subtropical region have nd values of around 5 suggesting that the deep waters are fed from the south along the western boundary ultimately from the antarctic bottom water aabw in the south pacific this extends up to 40 n along the japanese islands in the subarctic region 42 n the waters have more radiogenic nd with nd 4 0 throughout the water column presumably due to the supply of nd by weathering in such igneous provinces as the kuril kamchatska aleutian island chain the lateral inhomogeneity of the nd isotopic composition in pdw suggests that there may be different circulation and mixing regimes in the north pacific basin

the sedimentary flux of dissolved rare earth elements to the ocean abstract we determined pore fluid rare earth element ree concentrations in near surface sediments retrieved from the continental margin off oregon and california usa these sites represent shelf to slope settings which lie above within and below the oxygen minimum zone of the northeast pacific the sediments are characterized by varying degrees of net iron reduction with pore fluids from the shelf sites being generally ferruginous and the slope sediments having less pronounced iron reduction zones that originate deeper in the sediment package ree concentrations show maxima in shallow upper 2 10 cm subsurface pore fluids across all sites with concentrations that rise more than two orders of magnitude higher than seawater these pore fluid enrichments highlight the importance of a sedimentary source of rees to the ocean s water column here we use our measurements to estimate the diffusive flux of nd out of ocean sediments resulting in a global flux between 18 and 110 10 6 mol nd yr 1 while we do assume that our pore fluid profiles as well as the very limited data previously published are representative of a wide array of ocean environments this calculated flux can account for the modeled missing nd source flux 76 10 6 mol nd yr 1 in global budgets arsouze et al 2009 pore fluid normalized ree patterns show distinct variation in the middle ree and heavy ree enrichments with sediment depth and amongst sites these patterns show that the heavy ree enrichment of pore fluids at our deep slope site 3000 m water depth is closest to the heavy ree enrichment of seawater this observation supports the view that ree cycling within the upper ten centimeters of deep sea marine sediments as opposed to shallower continental shelf and slope sediments plays a significant role in controlling the integrated global ree flux from the pore fluids and consequently the broad scale ree pattern in seawater

the profile of the rare earth elements in the canada basin arctic ocean we analyzed the dissolved rare earth element ree content of three water column profiles two shelf sites and one deep basin site in the canada basin in order to better constrain the behavior of rees in the arctic ocean dissolved concentrations of the rees in the surface are 1 3 to 1 9 times higher than deep water 500 m concentrations which are constant with depth la 19 23 pm nd 14 17 pm yb 4 0 4 3 pm the dominant source of rees to the surface waters of the canada basin is most likely pacific water flowing through the bering strait and chukchi sea and or the mackenzie river dissolved rees in the intermediate and deep waters are constant and appear to behave conservatively allowing us to investigate this aspect of ree behavior in the oceans calculated deep ocean residence times of the rees in the canada basin range from 450 700 years and match the age of these waters we postulate that these values are likely applicable to global deep ocean reservoirs and that observed deviations from this conservative value can help to constrain non conservative processes acting on the rees this article is protected by copyright all rights reserved

a seismologically consistent expression for the total area and volume of earthquake triggered landsliding we present a new seismologically consistent expression for the total area and volume of populations of earthquake triggered landslides this model builds on a set of scaling relationships between key parameters such as landslide spatial density seismic ground acceleration fault length earthquake source depth and seismic moment to assess the model we have assembled and normalized a catalog of landslide inventories for 40 shallow continental earthquakes low landscape steepness causes systematic overprediction of the total area and volume of landslides when this effect is accounted for the model predicts the total landslide volume of 63 of 40 cases to within a factor 2 of the volume estimated from observations r2 0 76 the prediction of total landslide area is also sensitive to the landscape steepness but less so than the total volume and it appears to be sensitive to controls on the landslide size frequency distribution and possibly the shaking duration some outliers are likely associated with exceptionally strong rock mass in the epicentral area while others may be related to seismic source complexities ignored by the model however the close match between prediction and estimate for about two thirds of cases in our database suggests that rock mass strength is similar in many cases and that our simple seismic model is often adequate despite the variety of lithologies and tectonic settings covered this makes our expression suitable for integration into landscape evolution models and application to the anticipation or rapid assessment of secondary hazards associated with earthquakes

a global empirical model for near real time assessment of seismically induced landslides earthquake triggered landslides are a significant hazard in seismically active regions but our ability to assess the hazard they pose in near real time is limited in this study we present a new globally applicable model for seismically induced landslides based on the most comprehensive global dataset available we use 23 landslide inventories that span a range of earthquake magnitudes and climatic and tectonic settings we use logistic regression to relate the presence and distribution of earthquake triggered landslides with spatially distributed estimates of ground shaking topographic slope lithology land cover type and a topographic index designed to estimate variability in soil wetness to provide an empirical model of landslide distribution we tested over 100 combinations of independent predictor variables to find the best fitting model using a diverse set of statistical tests blind validation tests show the model accurately estimates the distribution of available landslide inventories the results indicate that the model is reliable and stable with high balanced accuracy correctly vs incorrectly classified pixels for the majority of test events a cross validation analysis shows high balanced accuracy for a majority of events as well by combining near real time estimates of ground shaking with globally available landslide susceptibility data this model provides a tool to estimate the distribution of coseismic landslide hazard within minutes of the occurrence of any earthquake worldwide for which a u s geological survey shakemap is available

depth dependence of anisotropy of earth s inner core both body wave pkp travel times creager 1992 song and helmberger 1993a mcsweeney and creager 1993 shearer 1994 and fits to the splitting of core modes tromp 1993 show general agreement that the top 300 km of inner core is very anisotropic the anisotropy displays axial symmetry around the earth s spin axis with the polar direction 3 faster than the equatorial direction one key problem now is the depth dependence of the inner core anisotropy here we extend our polar path studies to include both long period and short period modeling for the pkp phases at ranges 120 to 173 arrivals from the top of the inner core pkikp and reflections from the inner core boundary pkikp can be observed distinctly in short period records at ranges 130 to 140 and as waveform distortions in the long period records at ranges 130 to 146 these waveforms provide a new set of data for examining the topmost 150 km of the inner core which is not well sampled by the previous body wave travel times record sections of waves traversing the inner core nearly parallel to the earth s spin axis polar paths from three events two beneath the south sandwich islands and one along the macquarie ridge recorded at world wide standardized seismograph network canadian network and long range seismic measurements stations are analyzed our results suggest that the top 150 km of the inner core is only weakly anisotropic less than 1 with strong evidence indicating that the top 60 km is not anisotropic at all

presentation and analysis of a worldwide database of earthquake induced landslide inventories earthquake induced landslide eqil inventories are essential tools to extend our knowledge of the relationship between earthquakes and the landslides they can trigger regrettably such inventories are difficult to generate and therefore scarce and the available ones differ in terms of their quality and level of completeness moreover access to existing eqil inventories is currently difficult because there is no centralized database to address these issues we compiled eqil inventories from around the globe based on an extensive literature study the database contains information on 363 landslide triggering earthquakes and includes 66 digital landslide inventories to make these data openly available we created a repository to host the digital inventories that we have permission to redistribute through the u s geological survey sciencebase platform it can grow over time as more authors contribute their inventories we analyze the distribution of eqil events by time period and location more specifically breaking down the distribution by continent country and mountain region additionally we analyze frequency distributions of eqil characteristics such as the approximate area affected by landslides total number of landslides maximum distance from fault rupture zone and distance from epicenter when the fault plane location is unknown for the available digital eqil inventories we examine the underlying characteristics of landslide size topographic slope roughness local relief distance to streams peak ground acceleration peak ground velocity and modified mercalli intensity also we present an evaluation system to help users assess the suitability of the available inventories for different types of eqil studies and model development

a global slope unit based method for the near real time prediction of earthquake induced landslides abstract rapid assessment of spatial distribution of earthquake induced landslides could provide valuable information in the emergency response phase previous studies proposed global analyses with the aim of predicting earthquake induced landslide distributions in near real time however in all those studies mapping units are constituted by pixels which do not reflect homogeneously distributed physical property for a given terrain unit and whose size do not match the resolution of existing thematic data at global scale moreover none of the existing analyses considers sampling balance between different inventories or categorizing the inventories to construct a training set with higher statistical representativeness we develop an improved global statistical method to address these drawbacks we use slope units which are terrain partitions attributed to similar hydrological and geomorphological conditions and to processes that shape natural landscapes a set of 25 earthquake induced landslide events are selected and categorized based on the similarity between causal factors to determine the most relevant training set to make a prediction for a given landslide event as a result we develop a specific model for each category we sample an equal number of landslide points from each inventory to overcome the dominance of some inventories with large landslide population we use seven independent thematic variables for both categorizing the inventories and modeling based on logistic regression the results show that categorizing landslide events introduces a remarkable improvement in the modeling performance of many events the categorization of existing inventories can be applied within any statistical global approach to earthquake induced landslide events the proposed categorization approach and the classification performance can be further improved with the acquisition of new inventory maps

study on vertical profiles of rare earth elements by using an ocean general circulation model 1 observed vertical profiles of rare earth elements rees in the north pacific ocean show a systematic change from lighter to heavier rees their source and sink consist of external fluxes coming from the surface and the bottom of the ocean and internal recycling within the ocean in order to evaluate the role of each source and sink in controlling the vertical profiles of rees we conduct numerical simulations of rees by using an ocean general circulation model these simulations demonstrate that the shape of their vertical profiles is not directly related to the external sources from river runoff atmospheric dust deposition and coastal regions but is sensitive to the internal recycling processes within the ocean nutrient like treatment where rees are removed at the surface and released in the deep ocean is suitable for simulating the vertical profiles of lighter rees but not for heavier rees when the irreversible scavenging is considered as a sink term and particle dissolution is taken into consideration as a source term the vertical profiles of heavier rees can be reproduced but those of lighter rees cannot the observed difference in the vertical profiles among rees can be reproduced only when the reversible scavenging process is incorporated into the model only the reversible scavenging process accounts for the observed vertical profiles of different rees in comprehensive manner

earthquake triggered 2018 palu valley landslides enabled by wet rice cultivation the death toll and economic impact of an earthquake can be greatly exacerbated if seismic ground shaking triggers landslides earthquake triggered landslides typically occur in two different contexts localized failure of steep slopes and resulting landslides that pose a major threat to life in areas below and lateral spreading of nearly flat sediment plains due to shaking induced liquefaction which can damage large areas of critical infrastructure unexpected catastrophic landsliding triggered by the 28 september 2018 earthquake at palu indonesia did not occur in either typical context but produced both destructive outcomes here we show that alluvial ground failure in the palu valley was a direct consequence of irrigation creating a new liquefaction hazard aqueduct supported cultivation primarily of wet rice raised the water table to near ground level saturating sandy alluvial soils that liquefied in response to strong ground shaking large displacement lateral spreads occurred on slopes of 1 slopes steeper than 1 5 sourced long runout landslides and debris flows that swept through villages occupying the gentler slopes below the resulting damage and loss of life would probably not have occurred in the absence of a raised water table earthquake triggered landsliding of gentle irrigated alluvial slopes is an under recognized but avoidable anthropogenic hazard aqueduct supported cultivation of rice resulted in liquefaction of the alluvial soils that led to the landslides triggered by the palu 2018 earthquake according to satellite analyses

contrasting geochemical cycling of hafnium and neodymium in the central baltic sea the central baltic sea is a marginal brackish basin which comprises anoxic bottom waters and is surrounded by geological source terrains with a wide variety of compositions and ages this allows the investigation of water mass mixing using radiogenic isotope compositions of nd and hf as well as their geochemical cycling across varying redox conditions in the water column in this study we present the distribution of nd and hf concentrations and their isotopic compositions for 6 depth profiles and 3 surface water sites obtained during a cruise in the central baltic sea onboard the rv oceania as a part of the international geotraces program the results obtained indicate that nd isotopes effectively trace the mixing between more radiogenic saline waters from the south and unradiogenic fresh waters from the north which helps to understand the reliability of nd isotopes as water mass tracer in the open ocean in surface waters nd shows higher concentrations and less radiogenic isotope compositions at the northern stations which are progressively diluted and become more radiogenic to the south consistent with the counterclockwise circulation pattern of central baltic sea surface waters in contrast to the variable nd concentrations hf shows much less variability at the gotland deep station the nd concentrations of the euxinic waters are higher by a factor 10 than those of the overlying oxygen depleted waters whereas hf only shows small concentration variations this indicates faster removal of hf from the water column than nd moreover the dissolved hf isotope signatures document great variability but no consistent mixing trends our explanation is that hf has a lower residence time than nd and also that the hf isotope signatures of the sources are highly heterogeneous which is attributed to their differing magmatic and tectonic histories as well as incongruent post glacial weathering around the central baltic sea

seismically induced mass movements and volumetric fluxes resulting from the 2010 mw 7 2 earthquake in the sierra cucapah mexico the observation that sediment flux from mountain ranges struck by high magnitude earthquakes can be strongly influenced by coseismic mass movements brings into question the nature of coseismic deformation as a net contributor to mountain building to better constrain the role of high magnitude earthquakes in orogenesis high resolution data of earthquake induced mass wasting is required for areas of differing tectonic morphological and climatic settings here we compare the erosional flux to the tectonic flux associated with the 2010 mw 7 2 sierra el mayor earthquake in mexico and examine the landslide patterning of coseismic mass movements associated with this event the ruptured fault system has a significant strike slip component with subsidence along the eastern flank and uplift on the western flank of the range peak ground acceleration was highest along the steepest sections of the range such that the frequency of landslide occurrence was strongly correlated to slope gradient both vertical and horizontal coseismic displacement demonstrated a strong control over landslide initiation this result suggests that strike slip systems experience very different landslide patterning to thrust faults during earthquakes based on interferometric analysis of synthetic aperture radar images the earthquake resulted in a total uplifted volume of 41 6 106 m3 and a loss of 95 2 106 m3 due to subsidence this suggests a net tectonic volumetric flux of 53 6 106 m3 sediment mobilisation by coseismic landslides is estimated at 2 7 106 m3 derived from a manually mapped inventory using spot 5 multispectral imagery thus the net volume loss through coseismic subsidence of the mountain range generated a strongly negative mass flux which was only marginally enhanced by mass wasting

rare earth element association with foraminifera abstract neodymium isotopes are becoming widely used as a palaeoceanographic tool for reconstructing the source and flow direction of water masses a new method using planktonic foraminifera which have not been chemically cleaned has proven to be a promising means of avoiding contamination of the deep ocean palaeoceanographic signal by detrital material however the exact mechanism by which the nd isotope signal from bottom waters becomes associated with planktonic foraminifera the spatial distribution of rare earth element ree concentrations within the shell and the possible mobility of ree ions during changing redox conditions have not been fully investigated here we present ree concentration and nd isotope data from mixed species of planktonic foraminifera taken from plankton tows sediment traps and a sediment core from the nw atlantic we used multiple geochemical techniques to evaluate how where and when rees become associated with planktonic foraminifera as they settle through the water column reside at the surface and are buried in the sediment analyses of foraminifera shells from plankton tows and sediment traps between 200 and 2938 m water depth indicate that only 20 of their associated nd is biogenically incorporated into the calcite structure the remaining 80 is associated with authigenic metal oxides and organic matter which form in the water column and remain extraneous to the carbonate structure remineralisation of these organic and authigenic phases releases ions back into solution and creates new binding sites allowing the nd isotope ratio to undergo partial equilibration with the ambient seawater as the foraminifera fall through the water column analyses of fossil foraminifera shells from sediment cores show that their ree concentrations increase by up to 10 fold at the sediment water interface and acquire an isotopic signature of bottom water adsorption and complexation of ree3 ions between the inner layers of calcite contributes significantly to elevated ree concentrations in foraminifera the most likely source of ree ions at this stage of enrichment is from bottom waters and from the remineralisation of oxide phases which are in chemical equilibrium with the bottom waters as planktonic foraminifera are buried below the sediment water interface redox sensitive ion concentrations are adjusted within the shells depending on the pore water oxygen concentration the concentration of ions which are passively redox sensitive such as ree3 ions is also controlled to some extent by this process we infer that a the nd isotope signature of bottom water is preserved in planktonic foraminifera and b that it relies on the limited mobility of particle reactive ree3 ions aided in some environments by micron scale precipitation of mnco3 this study indicates that there may be sedimentary environments under which the bottom water nd isotope signature is not preserved by planktonic foraminifera tests to validate other core sites must be carried out before downcore records can be used to interpret palaeoceanographic changes

an updated geospatial liquefaction model for global application abstract we present an updated geospatial approach to estimation of earthquake induced liquefaction from globally available geospatial proxies our previous iteration of the geospatial liquefaction model was based on mapped liquefaction surface effects from four earthquakes in christchurch new zealand and kobe japan paired with geospatial explanatory variables including slope derived v s 30 compound topographic index and magnitude adjusted peak ground acceleration pga from shakemap the updated geospatial liquefaction model presented herein improves the performance and the generality of the model the updates include 1 expanding the liquefaction database to 27 earthquake events across six countries 2 addressing the sampling of nonliquefaction for incomplete liquefaction inventories 3 testing interaction effects between explanatory variables and 4 overall improving the model s performance we inspected 14 geospatial proxies for soil density and soil saturation the most promising of these are slope derived v s 30 modeled water table depth distance to coast distance to river distance to the closest water body and precipitation we found that peak ground velocity pgv performs better than pga as the shaking intensity parameter we present two models which offer improved performance over prior models we evaluate model performance using the area under the receiver operating characteristic curve and the brier score the best performing model in a coastal setting uses distance to the coast but is problematic for regions away from the coast the second best model using pgv v s 30 water table depth distance to the closest water body and precipitation performs better in noncoastal regions and thus is the model we recommend for global implementation

temporal relationships of carbon cycling and ocean circulation at glacial boundaries evidence from high sedimentation rate south atlantic deep sea cores indicates that global and southern ocean carbon budget shifts preceded thermohaline circulation changes during the last ice age initiation and termination and that these were preceded by ice sheet growth and retreat respectively no consistent lead lag relationships are observed during abrupt millennial warming events during the last ice age allowing for the possibility that ocean circulation triggered some millenial climate changes at the major glacial interglacial transitions the global carbon budget and thermohaline ocean circulation responded sequentially to the climate changes that forced the growth and decline of continental ice sheets

landslides triggered by the avaj iran earthquake of june 22 2002 abstract the 2002 avaj iran earthquake mw 6 5 triggered many landslides over an area of about 3600 km 2 in this paper we describe a ground based field study conducted during several days immediately after the earthquake and pre and post earthquake landslide inventory maps that were prepared the landslides due to earthquake include 47 fall and topple zones 9 slides and 3 lateral spreads the largest slide is a rockslide 150 100 m which occurred southeast of the village of changureh the main results of this study are the density of earthquake triggered landslides decreases away from the fault zone in a manner that is asymmetric with respect to direction although several slides and lateral spreads were seen the most common types of triggered landslides are falls and topples the area throughout which landslides occurred and maximum epicentral and fault zone distances of landslides are comparable to similar data from other historical earthquakes landslides mostly occurred in the most susceptible geologic units in which there were many landslides before the earthquake new disrupted slides and falls generally occurred in ancient fall zones but no information about reactivation of coherent slides is available

towards explaining the nd paradox using reversible scavenging in an ocean general circulation model abstract the isotopic composition of the rare earth element neodymium nd has the potential to serve as water mass tracer because it is naturally tagged by continental sources with distinct ages and lithologies however in order to understand the limitations of this approach we need to know more about the physical and biogeochemical processes controlling the distribution of nd in the modern ocean for example nd isotope ratios behave quasi conservatively while concentrations in the water column generally increase with depth showing a broadly nutrient like behaviour we define this decoupling of nd concentrations and isotopic compositions as the nd paradox for the first time we model nd concentrations and isotopic compositions simultaneously and address the hypothesis that the nd paradox can be explained by a combination of lateral advection and reversible scavenging we impose a reversible scavenging model of nd removal from the ocean on the ocean circulation fields from the mit general circulation model using the transport matrix method we conclude that reversible scavenging is an active and important component in the cycling of nd in the ocean in the absence of an adequate alternative explanation reversible scavenging should be considered a necessary component in explaining the nd paradox

intensification and variability of ocean thermohaline circulation through the last deglaciation neodymium isotope ratios in the authigenic ferromanganese oxide component in a southeastern atlantic core reveal a history of the global overturning circulation intensity through the last deglaciation from a minimum during the last glacial maximum lgm north atlantic deep water nadw began to strengthen between 18 and 17 kyr cal bp approximately 2000 3000 years before the bolling warming it exhibits a gradually increasing baseline intensity that plateaus in the early holocene tracks increasing northern hemisphere insolation and parallels atmospheric co2 concentration millennial scale fluctuations are superimposed on this baseline nadw increase corresponding to events in northern hemisphere climate records the millennial excursions show sharp increases associated with the pre bolling retreat of continental glaciers and the bolling warming itself a decrease with allerod cooling and a recovery through the younger dryas and early holocene the data confirm a close link between deep ocean circulation and north atlantic climate changes there is no clear linkage with meltwater pulses indicating that rapid meltwater additions did not trigger observable mode changes in nadw production however rapid changes in north atlantic sea ice cover show a strong relationship with the millennial perturbations of nadw flux to the deep southern ocean the data indicate that the baseline intensity of nadw reaching the cape basin is paced by northern hemisphere insolation and that north atlantic sea ice coverage acts as a major amplifying link between the oceans and the atmosphere d 2004 elsevier b v all rights reserved

a method for producing digital probabilistic seismic landslide hazard maps abstract the 1994 northridge california earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability these data sets include 1 a comprehensive inventory of triggered landslides 2 about 200 strong motion records of the mainshock 3 1 24 000 scale geologic mapping of the region 4 extensive data on engineering properties of geologic units and 5 high resolution digital elevation models of the topography all of these data sets have been digitized and rasterized at 10 m grid spacing using arc info gis software on a unix computer combining these data sets in a dynamic model based on newmark s permanent deformation sliding block analysis yields estimates of coseismic landslide displacement in each grid cell from the northridge earthquake the modeled displacements are then compared with the digital inventory of landslides triggered by the northridge earthquake to construct a probability curve relating predicted displacement to probability of failure this probability function can be applied to predict and map the spatial variability in failure probability in any ground shaking conditions of interest we anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure

rare earth elements in pore waters of marine sediments abstract the rare earth elements rees were measured in pore waters of the upper 25 cm of sediment from one site off peru and three sites on the california margin the pore water ree concentrations are higher than sea water and show systematic down core variations in both concentration and normalized pattern from these analyses and from comparison to other chemical species measured dissolved fe mn ba oxygen nitrate phosphate it is suggested that pore water rees can be grouped into three categories those that are from an fe source those that are from a poc source and cerium oxide rees from the fe source appear where anoxia is reached they have a distinctive middle ree mree enriched pattern the concentrations in this source are so elevated that they dominate ree trends in the fe oxide reduction zone the net result of flux from the poc source is relative enrichment of heavy rees hrees over light rees lrees reflecting remineralizing poc and complexation with doc a common linear ree pattern seen in both oxic and anoxic sediments is associated with this poc source as well as a hree enriched pattern that is seen in surficial sediments at the peru site overall the pore water results indicate that mn oxides are not an important carrier of rees in the oceans a ree biogeochemical model is presented which attempts to reconcile ree behavior in the water and sediment columns of the oceans the model proposes that poc fe oxide and ce oxide sources can explain the ree concentration profiles and relative abundance patterns in environments ranging from oxic sea water to anoxic pore water the model is also consistent with our observation that the ce anomaly of pore water does not exceed unity under any redox condition

new insights into cycling of 231pa and 230th in the atlantic ocean abstract we use the bern3d model of intermediate complexity to examine the marine cycle of isotopes 231pa and 230th and the relationship between the particle bound ratio pa p th p and changes in the formation of the north atlantic deep water nadw model parameters describing reversible scavenging of isotopes by organic particles opal calcite and resuspended sediments were systematically varied and alternative sink parametrisations explored it proves difficult to simultaneously achieve a good agreement with observations of dissolved and particle associated concentrations of 231pa and 230th pa d th d pa p th p as well as the particle bound ratio pa p th p within the classical concept of reversible scavenging alone agreement between simulated and observed pa d th d and estimates of mean ocean residence times is improved by taking into account simplified representations of additional sinks at the sea floor bottom scavenging and at continental boundaries boundary scavenging we also find improved agreement between model and data by increasing lateral advection in particular for pa d these results point to the importance of sink processes that act in addition to reversible scavenging to shape the steady state distribution of 231pa and to a lesser degree of 230th in transient experiments in which the strength of the atlantic meridional overturning circulation amoc is periodically turned on and off we find a strong statistical relationship between variations in amoc strength and pa p th p at great depths in the northwest atlantic region these conclusions are robust across the range of sink parametrisations that are consistent with estimates in the mean ocean residence time of 231pa and 230th our results indicate that the relationship between pa p th p and amoc strength may not be fundamentally affected by uncertainties in sink processes at least on the large spatial and temporal scale considered here and support the idea that changes in pa p th p in sediments of the northwest atlantic are indicative of changes in amoc strength taking into account our simplified approach our results indicate that the relationship between pa p th p and amoc strength in the deep northwest atlantic is not affected by boundary scavenging or bottom scavenging our results thus support the idea that changes in pa p th p in sediments of the northwest atlantic are indicative of changes in amoc strength

regional patterns of earthquake triggered landslides and their relation to ground motion 1 we have documented patterns of landsliding associated with large earthquakes on three thrust faults the northridge earthquake in california chi chi earthquake in taiwan and two earthquakes on the ramu markham fault bounding the finisterre mountains of papua new guinea in each case landslide densities are shown to be greatest in the area of strongest ground acceleration and to decay with distance from the epicenter in california and taiwan the density of co seismic landslides is linearly and highly correlated with both the vertical and horizontal components of measured peak ground acceleration based on this observation we derive an expression for the spatial variation of landslide density analogous with regional seismic attenuation laws in its general form this expression applies to our three examples and we determine best fit values for individual cases our findings open a window on the construction of shake maps from geomorphic observations for earthquakes in non instrumented regions

simulations of temperature and turbulence structure of the oceanic boundary layer with the improved near surface process an improved model for the oceanic boundary layer is presented in view of the recent observation of the microstructure of the upper ocean including the high dissipation rate near the sea surface in the new model the surface boundary conditions for both the turbulent kinetic energy flux and the roughness length scale are modified the parameterization of stratification effects on turbulence is improved and the convective process is reformulated on the basis of the observation of uniform temperature and velocity profiles within the convective mixed layer evolutions of the profiles of both the dissipation rate and temperature of the observation data patches experiment as well as the time series of the sea surface temperature over the observation days are successfully simulated during a diurnal cycle for the first time it is also shown that the model reproduces various important features of the oceanic boundary layer for example the formation of a diurnal thermocline the profiles of buoyancy flux and the magnitudes of the buoyancy gradients both within the mixed layer and at the diurnal thermocline performance of the model is compared with that of the widely used mellor yamada model

tracing papua new guinea imprint on the central equatorial pacific ocean using neodymium isotopic compositions and rare earth element patterns abstract the nd isotopic composition ic and rare earth patterns of hydrodynamic structures of the equatorial pacific ocean were characterized along 140 w the nd ic of antarctic intermediate water aaiw and of the lower layer of the equatorial undercurrent euc at 140 w 13 c water are much more radiogenic at the equator than at their origin in the south equatorial current 12 s revealing that these water masses have been in contact with the highly radiogenic papua new guinea png slope in both cases only a small fraction less than 9 of the sediment deposited on the png slope is required to be exchanged or dissolved to explain these nd ic variations whereas the hydrographic properties of the same water masses remain unchanged this confirms the usefulness of this tracer to identify pathways of water masses these results emphasize the importance of jets in transporting lithogenic material into the subsurface layers of remote areas where aeolian inputs are particularly weak and corroborate the previous results on fe and al maximum in this area m l wells g k vallis e a silver nature 398 1999 601 604 the nd ic of the upper layer of the euc contrasts strongly to that of the subpycnocline layer indicating that the equatorial upwelling only affects the surface waters and is not effective between 120 and 150 m we calculate that the nd imprint of the png input is likely to vanish from this surface layer as it traverses the basin due to the replacement of upwelled waters by non radiogenic ones

geostatistical modeling to capture seismic shaking patterns from earthquake induced landslides we investigate earthquake induced landslides using a geostatistical model featuring a latent spatial effect lse the lse represents the spatially structured residuals in the data which remain after adjusting for covariate effects to determine whether the lse captures the residual signal from a given trigger we test the lse in reproducing the pattern of seismic shaking from the distribution of seismically induced landslides without prior knowledge of the earthquake being included in the model we assessed the landslide intensity that is the expected number of landslides per mapping unit for the area in which landslides triggered by the wenchuan and lushan earthquakes overlap we examined this area to test our method on landslide inventories located in near and far fields of the earthquake we generated three models for both earthquakes i seismic parameters only proxy for the trigger ii the lse only and iii both seismic parameters and the lse the three configurations share the same morphometric covariates this allowed us to study the lse pattern and assess whether it approximated the seismic effects our results show that the lse reproduced the shaking patterns for both earthquakes in addition the models including the lse perform better than conventional models featuring seismic parameters only due to computational limitations we carried out a detailed analysis for a relatively small area 2 112 km2 using a data set with higher spatial resolution results were consistent with those of a subsequent analysis for a larger area 14 648 km2 using coarser resolution data

widespread landslides induced by the mw 5 1 earthquake of 11 may 2011 in lorca se spain abstract on 11 may 2011 a moderate magnitude mw 5 1 earthquake struck the city of lorca se spain and nearby areas causing notable damage injuries and fatalities field inspection of the area affected allowed the location and characterization of more than 250 induced landslides mainly of disrupted type rock soil falls disrupted soil slides and rock avalanches this number was very high when compared with the inventories of previous events of similar magnitude mw 4 7 to 5 0 in the zone and with the results of previous models for predicting slope behavior during earthquakes several factors are proposed here to explain the observed differences i the comparatively high magnitude mw 4 5 of a foreshock of the seismic series that may have weakened the slopes ii the high peak ground motion values recorded for these events and iii the occurrence of topographic site effects the results of this study point out the importance of including such effects as improvements in the models for studying the regional behavior of slopes

the geochemical balance of the rare earth elements and neodymium isotopes in the oceans profiles of ree concentrations and neodymium isotope measurements in the western indian ocean are consistent with published data from the other major oceans ree concentrations show a strong hydrographic control the influence of intermediate water masses is particularly significant surface water concentrations vary with salinity paniculate rees are less than 5 of dissolved concentration except for ce where up to 20 of total rees are present as 0 4 m particles in contrast to dissolved profiles concentration profiles of paniculate rees including ce all increase with depth ree concentrations correlate with silica over all but the deepest waters although in detail correlations are complex the neodymium isotopic composition of indian ocean seawater avg nd 0 8 3 is intermediate between that for the atlantic and pacific oceans comparison of ree data from the major oceans shows that the hrees behave more like si than do the lrees sm nd ratios are near constant for all oceans whereas ernd ratios vary between the atlantic indian and pacific oceans the fractionation of the rees in surface seawaters can be explained by fractionation factors relative to silica from 0 12 for la to 0 05 for er use of a seven box model shows that the interoceanic variations in neodymium isotopic compositions and nd concentrations cannot be reconciled unless particle water exchange is invoked the degree of exchange required is consistent with particle residence times of 1 10 yr

limits on conservative behavior of nd isotopes in seawater assessed from analysis of fish teeth from pacific core tops abstract neodymium nd isotopes have become an accepted water mass tracer for paleoceanographic reconstructions however high rates of radiogenic nd input from volcanic islands arcs in the western equatorial pacific wep and the subarctic north pacific sanp can significantly alter the isotopic composition of ambient seawaters leading to questions about the conservative nature of nd isotopes in the pacific here we present the first comprehensive study of nd isotopes preserved in core top fossil fish teeth debris from 31 sites in the pacific to define the vertical and horizontal distributions of seawater nd isotopes and to test the reliability of nd isotopes as a water mass tracer in the pacific we found that nd isotopic values of northward flowing lower circumpolar deep water lcdw are significantly modified in the western central equatorial pacific and the sanp as a result of local radiogenic inputs from young circum pacific island arcs consequently modified lcdw with 5 end is created in the central equatorial pacific while recirculated north pacific deep water npdw acquires a radiogenic nd isotope value 2 end in the sanp nd isotopic ratios of fish teeth debris in the central north pacific plotted against salinity or phosphate concentration from the overlying bottom water produce a mixing envelope between modified lcdw and npdw indicating that these nd isotopic values represent the southern and northern sourced end member values for the central north pacific and that mixing of these water masses defines vertical profiles of nd isotopes in this region in the eastern equatorial pacific eep three water masses modified lcdw npdwsanp and npdwwestern pacific combine to produce nd isotopic values that reflect this conservative mixture therefore nd isotopes behave as a conservative water mass tracer in the central north pacific and the eep but high rates of lithogenic inputs from young circum pacific island arcs compromise the conservative behavior of nd isotopes in the wep and sanp

modeling the distribution of nd isotopes in the oceans using an ocean general circulation model nd isotopic compositions of authigenic phases in marine archives are increasingly used as a tracer of past changes in ocean circulation such applications assume that water masses are tagged with distinct nd isotope compositions in source regions and that away from these regions the nd isotope ratios observed in deep waters mainly reflect water mass mixing however the degree to which the simple assumption of quasi conservative mixing reflects the complicated reality of general circulation in the oceans is not well understood here we present numerical simulations of the nd isotope distribution in seawater using an offline ocean general circulation model ogcm treating the nd isotopic composition of seawater as a conservative tracer nd isotope data from modern surface waters are used to generate an interpolated map of nd isotope compositions for the entire surface ocean this map is treated as a fixed surface boundary condition that is propagated into the interior ocean by the advective diffusive transport of the ocean model until a steady state is reached this treatment of nd isotopes was chosen because it mimics the behavior of well known and well understood conservative tracers such as potential temperature and salinity the model results for all non surface grid points are then compared to published data this simple approach produces nd isotope estimates for north atlantic deep water that are consistent with observations but produces values lower than observed in the deep pacific and southern oceans indicating the need for a source of radiogenic nd directly to the deep pacific ocean sensitivity tests show this to be a robust result by fixing the return flow of the pacific ocean to the southern ocean with nd isotope ratios that are consistent with modern observations the model results are brought into close agreement with a majority of the available data with the addition of a deep pacific source of radiogenic nd more than half of the simulated values from the interior ocean fall within one e unit of the corresponding observations our results thus indicate that the deep pacific ocean requires a source of radiogenic nd in addition to inputs to the surface ocean and that when the deep waters of the north atlantic and north pacific are set with realistic values a majority of intermediate areas are consistent with quasi conservative mixing of these two end members

landslides in eastern honshu induced by the 2011 tohoku earthquake in this article we discuss the character and spatial pattern of coseismic landslides from the eastern honshu region of japan which was strongly shaken in the 2011 tohoku earthquake we developed a detailed geospatial database of 3477 landslides based on postearthquake field surveys and examination of high resolution satellite imagery across a 28 380 km2 landslide study area analysis of the database shows that a substantial majority 80 of landslides occurred in quaternary soil and neogene rock units despite their abundance in the study area relatively few landslides occurred in pre neogene rocks i e older than 23 ma further examination of the data showed that the most common types of landslides were 1 disrupted landslides in neogene sedimentary rocks and 2 lateral spreading in quaternary sediments however we found that coseismic landslide erosion i e debris mobilization was almost fully dominated by lateral spreading within quaternary sediments when comparing the landslide inventory with ground motions recorded by dense regional seismic arrays we found no statistically significant correlation between landslide intensity and ground motion within the study area online material derivation of empirical parameters used in the area to volume transformations for lateral spreads

modeling the neodymium isotopic composition with a global ocean circulation model abstract for the first time modeling of the neodymium nd isotopic composition expressed as end is performed in an ocean global circulation model opa orca2 0 model in the interest of simplicity nd concentration is not explicitly included and end is modeled as a passive tracer recent studies suggest that dissolved particulate exchanges between continental margin sediments and seawater termed boundary exchange be could be the dominant source sink terms that determine the distribution of neodymium isotopes in the global ocean to test this hypothesis we only included this be source sink term in the model be was parameterized as a relaxing term that forces end of seawater to the isotopic composition of the continental margin over a characteristic exchange time sensitivity tests were made using different exchange times and parameterizations the model reproduces most of the general trends of end composition in seawater at global scale inter basin gradient composition of some of the main water masses these results suggest that be process may account for the major sources and sinks of oceanic nd while indicating that the characteristic time of interaction between seawater and margins varies from about half a year in surface waters to several years at depth the disparities between the model and observations might reflect the typical shortcomings of utilizing a coarse resolution ocean model circulation fields or neglected sources of neodymium such as dissolution of aeolian inputs or dissolved river loads

comparison of two landslide susceptibility assessments in the champagne ardenne region france abstract the vineyards of the montagne de reims are mostly planted on steep south oriented cuesta fronts receiving a maximum of sun radiation due to the location of the vineyards on steep hillslopes the viticultural activity is threatened by slope failures this study attempts to better understand the spatial patterns of landslide susceptibility in the champagne ardenne region by comparing a heuristic qualitative and a statistical quantitative model in a 1120 km study area the heuristic landslide susceptibility model was adopted from the bureau de recherches geologiques et minieres the gegeaa reims university and the comite interprofessionnel du vin de champagne in this model expert knowledge of the region was used to assign weights to all slope classes and lithologies present in the area but the final susceptibility map was never evaluated with the location of mapped landslides for the statistical landslide susceptibility assessment logistic regression was applied to a dataset of 291 old holocene landslides the robustness of the logistic regression model was evaluated and roc curves were used for model calibration and validation with regard to the variables assumed to be important environmental factors controlling landslides the two models are in agreement they both indicate that present and future landslides are mainly controlled by slope gradient and lithology however the comparison of the two landslide susceptibility maps through 1 an evaluation with the location of mapped old landslides and through 2 a temporal validation with spatial data of recent 1960 1999 n 48 and very recent 2000 2008 n 46 landslides showed a better prediction capacity for the statistical model produced in this study compared to the heuristic model in total the statistically derived landslide susceptibility map succeeded in correctly classifying 81 0 of the old and 91 6 of the recent and very recent landslides on the susceptibility map derived from the heuristic model on the other hand only 54 6 of the old and 64 0 of the recent and very recent landslides were correctly classified as unstable hence the landslide susceptibility map obtained from logistic regression is a better tool for regional landslide susceptibility analysis in the study area of the montagne de reims the accurate classification of zones with very high and high susceptibility allows delineating zones where viticulturists should be informed and where implementation of precaution measures is needed to secure slope stability

neodymium budget in the modern ocean and paleo oceanographic implications the oceanic nd budget is calculated using a steady state 10 box model and a compilation of field data this is the first attempt to propose consistent estimates of the nd fluxes entering the ocean as well as indicating possible nd sources and the proportion of nd fluxes exchanged between dissolved and particulate fractions with presently available nd data the best estimates give a total nd influx of 9 x 10 9 g yr which leads to an oceanic nd residence time of 500 years from modeling tests we suggest that the authigenic nd scavenged by particulates is 100 remineralized in the deep ocean the total exchanged nd flux may be as high as 2 x 10 10 g yr the epsilon nd 0 values of the influxes are 22 11 1 and 4 for the north atlantic surface atlantic north pacific and surface indo pacific regions respectively atmospheric and riverine nd fluxes are insufficient to explain the magnitude and regional variability of calculated nd influxes and epsilon nd 0 we propose continental margins as an additional source supplying nd to the ocean using the model calibrated for nd we examine the sensitivity of deep water epsilon nd 0 to variations of nd inputs to the ocean deep water nd concentrations and epsilon nd 0 vary with the changes in nd influxes and their epsilon nd 0 as nd sources to the ocean may change during glacial interglacial periods the epsilon nd 0 shifts recorded in ferromanganese nodules and crusts do not necessarily reflect changes in paleoceanic circulation the effects of continental erosion should be considered in reconstructing patterns of ocean circulation using nd isotopes