processing correlating and interpreting converted shear waves from borehole data in southern alberta borehole measurements coupled with phase information from zoeppritz equation modeling has assisted in accurate correlation between a vsp converted s wave section and both the surface and vsp p wave sections from southern alberta for the most part both the character and polarities of the sections agree however there are some differences some reflections are stronger and more distinct on the s wave section than on the p wave section spectral analysis of the time domain upgoing p wave and s wave energy shows that the frequency content of the s waves is comparable to the p waves thus the slower velocity s waves have a shorter wavelenght and provide better vertical resolution of some interfaces other upgoing s wave modes can interfere with the p sv mode and contribute to the differences between the p and s wave sections the match between p wave and s wave velocities vp and vs determined from vsp traveltime inversion and the full waveform sonic log is best in the paleozoic carbonate section ther

method for identification of shallow water flow hazards using marine seismic data the problem of detecting sedimentary formations having an abnormally high fluid pressure that are underneath a relatively impermeable formation having normal fluid pressures is addressed at shallow depths a formation with abnormally high fluid pressure has a shear velocity that is close to zero and is thus significantly different from the shear velocity of overlying sediments the high shear wave velocity contrast is detected by measuring a change in the amplitude of seismic waves reflected from the top of the abnormally pressured formation this may be done by an amplitude versus offset avo analysis of the reflected amplitudes of compressional or shear reflections measurements of the amplitude of reflected shear waves from a formation at some depth below the anomalous zone are may also be used to detect the presence of abnormally pressured intervals with low shear velocity and high shear wave attenuation

reconstruction of reflecting structures from vertical seismic profiles with a moving source when a vertical seismic profile vsp is recorded the illuminated part of a reflector depends upon the shape and position of the reflector itself as well as on the seismic velocities and the positions of sources and receivers a preferable arrangement for the investigation of structures of reflectors is to fix the receiver s at constant depth s in the well and move the source horizontally along a line at the earth s surface usually called a multioffset vsp msp or walkaway vsp as a test of the resolution power of this survey geometry synthetic records were generated from a subsurface model by inverse kirchhoff migration three different methods were applied for the reconstruction wavefront construction leads to the correct shape of the reflectors thus assuring the validity of the modeling method applied reflection point mapping delivered a near similarity to the model but without focusing fault edges kirchhoff migration resulted in a detailed image of the reflectors with fault edges focuse

gis based support vector machine modeling of earthquake triggered landslide susceptibility in the jianjiang river watershed china abstract support vector machine svm modeling is based on statistical learning theory it involves a training phase with associated input and target output values in recent years the method has become increasingly popular the main purpose of this study is to evaluate the mapping power of svm modeling in earthquake triggered landslide susceptibility mapping for a section of the jianjiang river watershed using a geographic information system gis software the river was affected by the wenchuan earthquake of may 12 2008 visual interpretation of colored aerial photographs of 1 m resolution and extensive field surveys provided a detailed landslide inventory map containing 3147 landslides related to the 2008 wenchuan earthquake elevation slope angle slope aspect distance from seismogenic faults distance from drainages and lithology were used as the controlling parameters for modeling three groups of positive and negative training samples were used in concert with four different kernel functions positive training samples include the centroids of 500 large landslides those of all 3147 landslides and 5000 randomly selected points in landslide polygons negative training samples include 500 3147 and 5000 randomly selected points on slopes that remained stable during the wenchuan earthquake the four kernel functions are linear polynomial radial basis and sigmoid in total 12 cases of landslide susceptibility were mapped comparative analyses of landslide susceptibility probability and area relation curves show that both the polynomial and radial basis functions suitably classified the input data as either landslide positive or negative though the radial basis function was more successful the 12 generated landslide susceptibility maps were compared with known landslide centroid locations and landslide polygons to verify the success rate and predictive accuracy of each model the 12 results were further validated using area under curve analysis group 3 with 5000 randomly selected points on the landslide polygons and 5000 randomly selected points along stable slopes gave the best results with a success rate of 79 20 and predictive accuracy of 79 13 under the radial basis function of all the results the sigmoid kernel function was the least skillful when used in concert with the centroid data of all 3147 landslides as positive training samples and the negative training samples of 3147 randomly selected points in regions of stable slope success rate 54 95 predictive accuracy 61 85 this paper also provides suggestions and reference data for selecting appropriate training samples and kernel function types for earthquake triggered landslide susceptibility mapping using svm modeling predictive landslide susceptibility maps could be useful in hazard mitigation by helping planners understand the probability of landslides in different regions

analyzing three component 3d vertical seismic profiling data a three component 3d vertical seismic profile vsp was acquired over the blackfoot oil field in alberta canada the vsp survey was recorded simultaneously with a surface seismic program the objectives of the vsp were to develop recording logistics data handling and processing procedures and to determine if the 3d vsp volumes could image the glauconitic sand reservoir of the blackfoot field dynamite shots from the surface seismic survey which fell within a 2200 m offset from the recording well were used in the vsp analysis the shots were recorded by a string of three component borehole receivers that was moved seven times resulting in a receiver depth range of 400 to 910 m the borehole data were processed using basic vsp processing techniques that included hodogram analysis wavefield separation using median filters and vsp deconvolution the final p p and p s image volumes were obtained by vsp common depth point and vsp common conversion point stacking the upgoing wavefields followed by f xy de

identifying post earthquake debris flow hazard using massflow catastrophic debris flows are common after large earthquakes and pose a significant risk for recovering communities the depositional volume of these large debris flows is often much greater than the initiation volume suggesting that bulking of the flow plays an important role in determining their volume speed and runout distance observations from recent earthquakes have driven progress in understanding the relationship between triggering rainfall events and the timing of post earthquake debris flows however we lack an adequate mechanism for quantifying bulking and applying it within a hazard context here we apply a 2d dynamic debris flow model massflow that incorporates a process based expression of basal entrainment to understand how debris flow bulking may occur within post earthquake catchments and develop hazard maps focussing on catchments in the epicentral area of the 2008 mw 7 9 wenchuan earthquake we first parameterised the model based on a large debris flow that occurred within the hongchun catchment before applying the calibrated model to adjoining catchments a model sensitivity analysis identified three main controls on debris flow bulking the saturation level of entrainable material along the flow pathway and the size and position of initial mass failures the model demonstrates that the difference between small and very large debris flows occur across a narrow range of pore water ratios below 0 65 flows falter at the base of hillslopes and come to rest in the valley bottom above 0 70 they build sufficient mass and momentum to sustain channelised flow and transport large volumes of material beyond the valley confines finally we applied the model across different catchments to develop hazard maps that demonstrate the utility of massflow in post earthquake planning within the wenchuan epicentral region

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

trace metal enrichments in the mediterranean sea copper nickel and cadmium occur at higher concentrations in the surface waters of the mediterranean than in nutrient depleted waters of the open ocean trace metal profiles have been taken on both sides of the strait of gibraltar to constrain a mass balance deep mediterranean waters have trace metal levels comparable to surface waters in regions of mediterranean deep water formation implying a minimal role for vertical transport by biological activity excess trace metals are not present in open atlantic source waters but a detailed map of trace metal distributions in the alboran sea immediately east of the strait reveals a metal enriched plume with concentrations as high as copper 3 6 nmol kg nickel 2 8 nmol kg and cadmium 120 pmol kg a substantial enrichment in trace metal concentrations therefore can occur in transit from the open atlantic through the coastal zone into the strait this trace metal enrichment may derive either from river inflow masked by evaporation diffusion out of continental shelf sediments eolian particulate fallout or anthropogenic sources metal sources fluvial sedimentary or atmospheric natural or anthropogenic are difficult to discern from the large scale oceanographic distribution metal retention in nutrient depleted surface waters is not due to unusual metal fluxes relative to nutrients but instead is a consequence of less frequent recycling of nutrients in the mediterranean compared to the open ocean metal enrichments would be expected before human intervention with anthropogenic input reflected in proportion to the relative augmentation of inputs over natural levels mediterranean water produces small trace metal anomalies in the outflow core positive for ni negative for cd present observations are consistent with this prediction but high precision data would be necessary to observe these at distance from gibraltar

rapid map and inversion of p sv waves multicomponent seismic recordings are currently being analyzed in an attempt to improve conventional p wave sections and to find and use rock properties associated with shear waves e g dohr 1985 danbom and dominico 1986 mode converted p sv waves hold a special interest for several reasons they are generated by conventional p wave sources and have only a one way travel path as a shear wave through the typically low velocity and attenuative near surface for a given frequency they will have a shorter wavelength than the original p wave and thus offer higher spatial resolution this has been observed in several vertical seismic profiling vsp cases e g geis et al 1990 however for surface seismic data converted waves are often found to be of lower frequency than p p waves e g eaton et al 1991

sources of debris flow material in burned areas abstract the vulnerability of recently burned areas to debris flows has been well established likewise it has been shown that many if not most post fire debris flows are initiated by runoff and erosion and grow in size through erosion and scour by the moving debris flow as opposed to landslide initiated flows with little growth to better understand the development and character of these flows a study has been completed encompassing 46 debris flows in california utah and colorado in nine different recently burned areas for each debris flow progressive debris production was measured at intervals along the length of the channel and from these measurements graphs were developed showing cumulative volume of debris as a function of channel length all 46 debris flows showed significant bulking by scour and erosion with average yield rates for each channel ranging from 0 3 to 9 9 m 3 of debris produced for every meter of channel length with an overall average value of 2 5 m 3 m significant increases in yield rate partway down the channel were identified in 87 of the channels with an average of a three fold increase in yield rate yield rates for short reaches of channels up to several hundred meters ranged as high as 22 3 m 3 m debris was contributed from side channels into the main channels for 54 of the flows with an average of 23 of the total debris coming from those side channels rill erosion was identified for 30 of the flows with rills contributing between 0 1 and 10 5 of the total debris with an average of 3 debris was deposited as levees in 87 of the flows with most of the deposition occurring in the lower part of the basin a median value of 10 of the total debris flow was deposited as levees for these cases with a range from near zero to nearly 100 these results show that channel erosion and scour are the dominant sources of debris in burned areas with yield rates increasing significantly partway down the channel side channels are much more important sources of debris than rills levees are very common but the size and effect on the amount of debris that reaches a canyon mouth is highly variable

estimation of debris flow magnitude in the eastern italian alps the estimation of debris ow magnitude is an essential step in the assessment of debris ow hazard although different methods have been developed for the assessment of debris ow magnitude this is still a dif cult task because of the complexity of ow processes and the lack of data to test estimation procedures in many mountainous regions data on debris ow magnitude from 127 basins in the eastern italian alps have been collected from scienti c and technical journals technical reports historical documents gathered from local archives and eld surveys these data were used to develop and test different predictive approaches encompassing regression equations geomorphological surveys and probabilistic analysis of time series regression techniques were used to correlate debris ow magnitude to morphometric parameters and geological characteristics of the basins values of the channel debris yield rate contribution per unit length of channel proposed in the literature were compared with data from the study area for identifying reference values for channel stretches of different morphological characteristics although limited to the few basins in which suf cient data were available the probabilistic analysis of time series of debris ow magnitude provides indications about the relations between magnitude and frequency of debris ows some observations about the capability and drawbacks of considered methods are presented and the combined use of different approaches for the estimation of debris ow magnitude is suggested copyright 2004 john wiley sons ltd

the role of debris supply conditions in predicting debris flow activity debris flow frequency and magnitude were determined for 33 basins in southwest british columbia basins were first classifiedaseitherweathering limitedortransport limitedusingadiscriminantfunctionbasedondebris contributingarea an area weighted terrain stability number and drainage density multiple regression was used to predict magnitude peak discharge frequency and activity frequency times magnitude within each group of basins model performance was improved by stratifying the total sample of debris flow basins into weathering and transport limited groups explained varianceincreasedbyanaverageof15percentinthetransport limitedsample indicatingthatsedimentsupplyconditionsin themoreactivebasinsarefundamentalinpredictingdebrisflowactivity anindependenttestoftheregressionmodelswith 11basinsyieldedgenerallygoodresultsfordebrisflowmagnitudeandpeakdischarge predictionofdebrisflowfrequency provedproblematicalinweathering limitedbasins themethodsdevelopedhereprovideestimatesofdebrisflowattributes in basins for which few data on past events are available copyright 1999 john wiley sons ltd

offset source vsp surveys and their image reconstruction zero offset source vsp surveys provide information about the subsurface only within the fresnel zone centered at the well offsetting the source location moves the reflection zones away from the well thus providing lateral cover conventional processing of this type of data gives rise to a distorted image of the subsurface using a simple ray tracing scheme this image may be reconstructed into the more familiar coordinate system of the surface seismic section this simple data independent mapping is based on the assumption of horizontal layering and requires a vertical velocity profile the technique of placing the source away from the borehole was first applied to the single offset source vsp survey however data from any survey geometry such as deviated well with rig source walkaway vsp etc can be mapped to the coordinate system defined by the appropriate seismic section to obtain the best results from this type of survey the target area must be defined and simple modeling techniques used to optimize the source location s these pre survey modeling methods may also be used to anticipate and hence avoid a number of problem areas which experience has highlighted the data from any vsp survey is the result of a realizable experiment and as such obeys the wave equation this implies that the wave equation may be used to migrate the data to its true subsurface location theoretically such a process is more secure than ray tracing techniques although its practice presents many difficulties

rapid vsp cdp mapping of 3 d vsp data vertical seismic profiling common depth point vsp cdp mapping with rapid ray tracing in a horizontally layered velocity model is used to create 3 d image volumes using blackfoot and oseberg 3 d vertical seismic profiling vsp data the ray tracing algorithm uses fermat s principle and is specially programmed for the layered model the algorithm is about ten times faster than either a 3 d vsp cdp mapping program with an eikonal traveltime computation method or a 3 d vsp kirchhoff migration program the mapping method automatically separates the image zone from the nonimage zone within the 3 d image volume the oseberg data example shows that the lateral extent of the image zone created by the 3d vsp cdp mapping is larger than that created by 3 d vsp kirchhoff migration the same sample result also provides high frequency events at target zones we include an analysis of the imaging error induced from using a horizontally layered model for the oseberg data indicating that the method is reliable in the presence of gently dipping structure

empirical models to predict the volumes of debris flows generated by recently burned basins in the western u s abstract recently burned basins frequently produce debris flows in response to moderate to severe rainfall post fire hazard assessments of debris flows are most useful when they predict the volume of material that may flow out of a burned basin this study develops a set of empirically based models that predict potential volumes of wildfire related debris flows in different regions and geologic settings the models were developed using data from 53 recently burned basins in colorado utah and california the volumes of debris flows in these basins were determined by either measuring the volume of material eroded from the channels or by estimating the amount of material removed from debris retention basins for each basin independent variables thought to affect the volume of the debris flow were determined these variables include measures of basin morphology basin areas burned at different severities soil material properties rock type and rainfall amounts and intensities for storms triggering debris flows using these data multiple regression analyses were used to create separate predictive models for volumes of debris flows generated by burned basins in six separate regions or settings including the western u s southern california the rocky mountain region and basins underlain by sedimentary metamorphic and granitic rocks an evaluation of these models indicated that the best model the western u s model explains 83 of the variability in the volumes of the debris flows and includes variables that describe the basin area with slopes greater than or equal to 30 the basin area burned at moderate and high severity and total storm rainfall this model was independently validated by comparing volumes of debris flows reported in the literature to volumes estimated using the model eighty seven percent of the reported volumes were within two residual standard errors of the volumes predicted using the model this model is an improvement over previous models in that it includes a measure of burn severity and an estimate of modeling errors the application of this model in conjunction with models for the probability of debris flows will enable more complete and rapid assessments of debris flow hazards following wildfire

debris flow volume quantile prediction from catchment morphometry estimation of the volumes of potential future debris flows is a key factor in hazard assessment and mitigation worldwide however there are few catchments for which detailed volume frequency information is available we 1 reconstructed volume frequency curves for 10 debris flow catchments in saline valley california usa from a large number of well preserved unmodified surficial flow deposits and 2 assessed the correlations between lobe volume quantiles and a set of morphometric catchment characteristics we found statistically significant correlations between lobe volume quantiles including median and maximum and catchment relief length planimetric distance from the fan apex to the most distant point along the watershed boundary perimeter and melton ratio relief divided by the square root of catchment area these findings show that it may be possible to roughly estimate debris flow lobe volume quantiles from basic catchment characteristics that can be obtained from globally available elevation data this may assist in design volume estimation for debris flow catchments where past flow volumes are otherwise unknown

positive feedback and momentum growth during debris flow entrainment of wet bed sediment debris flows typically occur when intense rainfall or snowmelt triggers landslides or extensive erosion on steep debris mantled slopes the flows can then grow dramatically in size and speed as they entrain material from their beds and banks but the mechanism of this growth is unclear indeed momentum conservation implies that entrainment of static material should retard the motion of the flows if friction remains unchanged here we use data from large scale experiments to assess the entrainment of bed material by debris flows we find that entrainment is accompanied by increased flow momentum and speed only if large positive pore pressures develop in wet bed sediments as the sediments are overridden by debris flows the increased pore pressure facilitates progressive scour of the bed reduces basal friction and instigates positive feedback that causes flow speed mass and momentum to increase if dryer bed sediment is entrained however the feedback becomes negative and flow momentum declines we infer that analogous feedbacks could operate in other types of gravity driven mass flow that interact with erodible beds the mechanisms by which debris flows acquire mass and momentum as they entrain material are unclear large scale experiments suggest that the pore pressure of wet bed sediment increases as the flow moves over the bed leading to reduced friction and progressive scouring of the base

catastrophic debris flows on 13 august 2010 in the qingping area southwestern china the combined effects of a strong earthquake and subsequent rainstorms in the wenchuan area in sw china an abundance of loose co seismic landslide debris was present on the slopes after the wenchuan earthquake which in later years served as source material for rainfall induced debris flows or shallow landslides slopes composed of cambrian sandstones and siltstones intercalated with slates appeared to be most susceptible to co seismic landsliding a total of 20 debris flows are described in this paper all were triggered by heavy rainfall on 13th of august 2010 field reconnaissance and measurements supported by aerial photo interpretation were conducted to identify the locations and morphological characteristics of the debris flow gullies in order to obtain information about surface area and volume of landslides and the debris flows the debris flows in the study area were initiated by two processes a run off erosion on co seismic landslide material and concentrated erosion of landslide debris in steep channels b new landslides that transform into debris flows the volume of debris flow deposits on individual fans varies by many orders of magnitude the smallest deposit has a volume of from 5760 to 3 1 million m3 a comparison of the measured volumes deposited on the fan with the volumes of debris stored in the catchment shows the huge potential for future debris flow activity whilst there is a weakly significant positive correlation between these two volumes no significant statistical correlation could be established between volumes of debris flow deposits and other morphometric parameters of the catchment a catastrophic debris flow catchment the wenjia catchment was selected as an extreme case to show in detail the mechanism of debris flow formation as a result of intensive erosion in loose material which was deposited by a rock avalanche during the 2008 earthquake event analyses of the meteorological conditions that triggered these debris flows show one day antecedent precipitation varying between 67 7 and 137 6 mm with a mean rainfall intensity of about 7 3 to 22 5 mm h a rainfall event with peak intensity of 38 7 mm h triggered the largest debris flow event rainfall data related to five debris flow events in the wenjia torrent was used to establish a primary rainfall intensity duration relationship for the triggering of debris flows which was compared to other rainfall duration thresholds from other parts of the world in the discussion emphasis is laid on the need to unravel the process mechanisms which initiated the debris flows for a better understanding and assessment of meteorological thresholds

migration of mixed mode vsp wavefields1 two dimensional vsp surveys are often conducted to provide structural illumination of the subsurface away from the borehole the illumination is achieved through offsetting the source with respect to the downhole geophone this inevitably gives rise to mode conversions in both downgoing and upgoing wavefields migration of mixed mode wavefields is complex because the velocity profile used for wavefield extrapolation is valid only for a particular propagation mode the other mode always propagates at a different velocity it is therefore advisable to separate the wave types p wave and sv wave prior to migration this may be achieved through wavemode filtering a multichannel process which exploits the relation between propagation velocity slowness of events at the recording array and particle motion the necessary information about particle motion is available only if the vsp data are acquired with a three component downhole geophone assembly the wavemode filter partitions wave types at the recording array it provides no information about the various changes of propagation mode experienced by the energy as it travels from source to geophone for the purpose of migration the intermediate modes of propagation must be deduced much of the energy arriving at the receivers is p wave which has followed the p wave velocity profile from the source it can therefore be imaged by conventional kirchhoff migration as an example of sv wave imaging a common mode code is p wave from source to reflector and sv wave from reflector to geophone migration of such data calls for back propagation of the geophone array wavefield at sv wave velocity to the point in the subsurface where it is time coincident with the forward propagated downwave at p wave velocity

north sea reservoir description benefits of an elastic migration inversion applied to multicomponent vertical seismic profile data a linearized elastic migration inversion m i technique is applied to multicomponent offset vsp data collected in the north sea high resolution elastic images of the target zone p and s wave velocities and density are obtained from upgoing p p and p s wave fields these m i images are an approximate representation of rapid variations of subsurface parameters three image confidence criteria provide a measure of uncertainty in the interpretation vsp cdp transform maps assisted in the definition of the confidence region in m i images m i was helpful in delineating the brent reservoir and detecting a twofault system preliminary interpretation indicates an increase in poisson s ratio at the top of the reservoir surface data were not able to image this target due to strong multiples at the cretaceous base this is the first time elastic depth images have been obtained from m i of offset vsp field data generally image artifacts depend on the following conditions 1 good quality data with satisfact

seismic transmission survey mapping in two layered media i propose a new concept of a seismic survey which takes advantage of mode converted transmission waves this method furnishes us with valuable information independent of any other survey which have been used to explore the earth s structure in the seismic reflection survey both not mode converted and mode converted reflection waves are used in order to obtain the section of the reflectivity in the seismic transmission survey refraction waves with mode changes from p to sv or from sv to pin propagating through the interfaces are used in order to obtain the section of the transmissivity the model consists of only a horizontally layered elastic medium to correct the normal move out of the transmission waves i apply the method which have been developed to process the mode converted reflection waves the approximation error is estimated by comparing with the exact solution in the case of a horizontally two layered medium numerical simulations prove that this method is available for the two layered medium with the discontinuity which has the inclination of 30 degrees

uncertainty of debris flow mobility relationships and its influence on the prediction of inundated areas abstract empirical mobility relationships can be used for delineating debris flow inundated areas a database of documented events in alpine mountain catchments of northeastern italy is used to test the model dflowz berti and simoni 2007 we back analyzed 25 df events ranging in volume from 3000 to 350 000 m 3 with the support of high resolution topographic information derived from lidar the analysis makes use of an objective methodology for evaluating the accuracy of the predictions and involves the calibration of the model based on factors describing the uncertainty associated with the empirical relationships results indicate that the model is capable of reproducing the observed behavior with a maximum uncertainty of a factor of 3 the most relevant source of error lies in the estimation of the deposited volumes which affects the results of back calculation and is mainly responsible also for the scatter associated with the empirical mobility relationships on the contrary the influence of different flow properties on the depositional process appears to play a minor role as the mutual relations between the three main scaling parameters volume inundated area and cross sectional area are respected in the vast majority of cases and calibrated mobility coefficients show no significant relationship with the angle of reach of the deposit

application of time series analysis and pso svm model in predicting the bazimen landslide in the three gorges reservoir china abstract the landslide displacement in the three gorges reservoir china experiences step like deformation that is influenced by rainfall and the periodic scheduling of the reservoir in view of the step like characteristic the particle swarm optimization and support vector machine pso svm coupling model based on the response of the induced factors was proposed to predict the landslide displacement the moving average method was adopted to divide the total displacement into trend term and periodic term the trend displacement was controlled by the geological conditions and predicted by polynomial function while the periodic displacement was under the combined control of the triggers and the evolution state of the landslide therefore the pso svm model based on the factors of the precipitation the variation range of the reservoir and the displacements of the prior periods was proposed to predict the periodic displacement the typical step like landslide in the three gorges reservoir which is known as the bazimen landslide was taken as a case study to verify the prediction results the values of the root mean square error and the mean absolute percentage error were 13 28 and 25 95 respectively the results showed that rainfall and reservoir water level were the dominant factors for the step like landslide deformation the evolution state of the landslide was also significant in reflecting the response relationship between the displacement and inducing factors in conclusion the proposed pso svm model can better represent the response relationship between the factors and the periodic displacement which made the predicted values of the total displacement fit with the measured values greatly

a hybrid machine learning model to estimate potential debris flow volumes abstract empirical statistical models of debris flow are challenging to implement in environments where sedimentary and hydrologic triggering processes change through time such as after a large earthquake the flexible and adaptive statistical methods provided by machine learning algorithms may improve the quality of debris flow predictions where triggering conditions and the nature of sediment that can bulk flows varies with time we developed a hybrid machine learning model of future debris flow volumes using a dataset of measured debris flow volumes from 60 catchments that generated post wenchuan earthquake mw 7 9 debris flows we input topographic variables catchment area topographic relief channel length distance from seismic fault and average channel gradient and the total volume of co seismic landslide debris into the pso elm adaboost machine learning model created by combining extreme learning machine elm particle swarm optimization pso and adaptive boosting machine learning algorithm adaboost the model was trained and tested using post 2008 mw 7 9 wenchuan earthquake debris flows then applied to understand potential volumes of post earthquake debris flows associated with other regional earthquakes 2013 mw 6 6 lushan earthquake 2010 mw 6 9 yushu earthquake we compared the pso elm adaboost method with different machine learning methods including back propagation neural network bpnn support vector machine svm elm pso elm the comparative analysis demonstrated that the pso elm adaboost method has a higher statistical validity and prediction accuracy with a mean absolute percentage error mape less than 0 10 the prediction accuracy of debris flow volumes trigged by other earthquakes decreases to 0 11 0 16 absolute percentage error suggesting that once calibrated for a region this method can be applied to other regional earthquakes this model may be useful for engineering design to mitigate the risk of large post earthquake debris flows

vertical seismic profiling vertical seismic profiling is one of the rapidly developing areas of geophysical technology for exploring in mature basins the measurement basically involves recording the total upgoing and downgoing seismic wave fields propagating through a stratigraphic section by means of geophones clamped to the wall of a drilled well

evolution of debris flow activities in gaojiagou ravine during 2008 2016 after the wenchuan earthquake abstract the 2008 wenchuan earthquake in sichuan china triggered numerous landslides in the stricken area the loose landslide materials retained on mountain slopes and in gullies are prone to reactivation and may transform into debris flows in the rainy season nine years after the wenchuan earthquake debris flows are still active in gaojiagou ravine 16 5 km north of the epicentre on 14 august 2010 3 july 2011 13 july 2013 and 6 july 2016 four large scale debris flows were triggered by heavy storms in gaojiagou ravine the four debris flows blocked the minjiang river twice and caused severe damage to nearby villages and reconstruction sites several questions arise from these repeated debris flows did the level of triggering rainfall change in the four debris flow events how did the initiation mechanism evolve over time what are the differences in the runout characteristics in the four events how did the check dams constructed in 2012 function in the subsequent debris flows in this paper we evaluated the loose deposit volumes in gaojiagou ravine before and after each of the four debris flows and the runout volumes and analysed the triggering rainfall intensities initiation mechanisms and runout characteristics of the four debris flows the rainfall threshold for the debris flows in gaojiagou ravine increased over time and the initiation mechanisms evolved from landslides to channel bed failure and subsequently to channel bank erosion the mobility of the debris flows decreased from 2010 to 2016 as the initiation positions moved lower and the particle size of the runout materials became coarser

use of backpropagation neural network for landslide monitoring a case study in the higher himalaya abstract this paper presents a case study of landslide monitoring and evaluation at okharpauwa 19 km chainage along kathmandu trishuli highway in nepal an attempt has been made to predict slope movements using backpropagation neural network bpnn a matlab based bpnn model is developed and the data from the case study are used to train and test the developed model to enable prediction of the magnitude of the ground movements with the help of input variables that have direct physical significance an infiltration coefficient is introduced in the network architecture apart from antecedent rainfall slope profile groundwater level and shear strength of soil a four layered backpropagation neural network with an input layer two hidden layers and one output layer is found optimal the developed bpnn model demonstrates a promising result and fairly accurately predicts the slope movement

determination of the copper isotope composition of seawater revisited a case study from the mediterranean sea abstract a new technique for the determination of dissolved copper isotope composition 65cu of seawater was applied to examine copper sources and internal cycling in the mediterranean sea along the geotraces ga04n transect a succession of chelating resin with nitrilotriacetic acid functional groups and strong base anion exchange resin together with optimization of the multi collector inductively coupled plasma mass spectrometry set up allowed to isolate copper from seawater matrix and to measure the 65cu 63cu ratios in seawater with an external precision of 0 06 2 s d this method was first applied for inter comparison measurements to surface and deep waters sampled at the bermuda atlantic time series station bats in the north atlantic ocean during the geotraces intercalibration cruise 1 disparities in 65cu reported here and in the literature over these samples showed a need to investigate whether a new inter comparison sample should be decided upon or whether the use of uv oxidation can also affect the measurement of 65cu we also measured total dissolved cu concentration dcu t and 65cu for 12 stations in the mediterranean sea the 65cu distribution showed significant variations in the euphotic zone at the chl a maximum and at bottom depths copper isotope ratios ranged from 0 21 to 0 76 0 06 2 s d yielding an average of 0 51 0 20 2 s d n 96 for the mediterranean sea a strong zonation between natural aerosol deposition to the south and anthropogenic aerosol deposition to the north was seen in the sample set dulaquais et al 2017 gerringa et al 2017 rolison et al 2015 natural dust deposits seemed to draw 65cu toward lower values and deeper in the euphotic zone whereas the impact of anthropogenic aerosols seemed restricted to an increase in dcu t at the chl a maximum 65cu showed significant increase which we attributed to scavenging on and or uptake by phytoplankton the isotope signature of cu sources to the mediterranean sea was also investigated and we inferred a significant source of isotopically heavy cu in the gibraltar area potentially originating from a release of cu sulfide leached in the mining area of southern spain i e iberian pyrite belt in rivers and transported to the mediterranean sea in surface by seasonal water mass circulation conversely marine sediments appear to be a source of isotopically light cu to deep waters this study provides new hints on the use of copper isotopes to study sources and sinks of cu in seawater this article is part of a special issue entitled cycles of trace elements and isotopes in the ocean geotraces and beyond edited by tim m conway tristan horner yves plancherel and aridane g gonzalez

effects of topography lithology rainfall and earthquake on landslide and sediment discharge in mountain catchments of southeastern taiwan abstract from 1996 through 2007 several heavy typhoons and earthquakes precipitated landslide hazards in southeast taiwan in the present study we analyze the impact of topography lithology rainfall and earthquakes on landsliding and sediment transport by quantifying the landslide ratio ratio of landslide area to catchment area and the sediment discharge for the sinwulu and luye upstream catchments of the peinan river the steep topography in these two catchments causes a large proportion of landslide ratios on slopes to exceeding 50 a condition which accelerates the delivery of landslide debris to the downslope channel the landslide ratios of 0 84 2 30 are obviously related to the rock strength and discontinuity density of the terrain but we find the magnitude of landsliding and sediment discharge to vary with the occurrence of earthquakes typhoon induced rainstorms generate the bulk of sediment discharge in the study catchments though the landslide debris is transported by the huge amounts of runoff produced by rainstorms a contributing factor is the recent occurrence of severe earthquakes which weakened the geomaterial leading in turn to further increases of fluvial sediment during subsequent typhoons additionally the finding that eventual reduction of unit sediment concentration after high magnitude earthquake events reveals that the downslope transport of landslide debris associated with earthquake activity and subsequent typhoon events precipitates a relatively short term 1 3 year increase of erosion rates in these two study areas in southeastern taiwan

converted wave seismic exploration methods multicomponent seismic recording measurement with vertical and horizontal component geophones and possibly a hydrophone or microphone captures the seismic wavefield more completely than conventional single element techniques in the last several years multicomponent surveying has developed rapidly allowing creation of converted wave or p s images these make use of downgoing p waves that convert on reflection at their deepest point of penetration to upcoming s waves survey design for acquiring p s data is similar to that for p waves but must take into account subsurface vp vs values and the asymmetric p s ray path p s surveys use conventional sources but require several times more recording channels per receiving location some special processes for p s analysis include anisotropic rotations s wave receiver statics asymmetric and anisotropic binning nonhyperbolic velocity analysis and nmo correction p s to p p time transformation p s dip moveout prestack migration with two velocities and wa

entrainment of trace metal enriched atlantic shelf water in the inflow to the mediterranean sea surface waters of the mediterranean sea have higher trace metal concentrations than open atlantic surface waters1 this observation could be explained by sources within the basin but recent data from the alboran sea2 indicate that trace metals may already be enriched in atlantic waters flowing into the mediterranean through the strait of gibraltar here we present new data documenting the presence of trace metal enriched source waters west of the strait and present a mathematical analysis showing that cu ni cd and zn distributions in the alboran sea can be explained as linear mixtures of four well defined sources 1 spanish coastal waters 2 north atlantic central water 3 atlantic surface water and 4 mediterranean levantine intermediate water in this analysis salinity and trace metals are used for the first time to deconvolve mixing between water masses of different origins