geomorphologic characteristics of catastrophic landslides during typhoon morakot in the kaoping watershed taiwan abstract a high resolution digital elevation model dem and field investigations are used to analyze the distribution and characteristics of rainfall induced landslides in the kaoping watershed of southwest taiwan during typhoon morakot the heavy rainfall brought by typhoon morakot is characterized as high intensity and long duration with a return period well over 200 years the landslide distribution correlates well with the heavy rainfall distribution heavy rainfall and flood triggered 12 697 landslides including four giant landslides the cumulative area of the landslides was 183 1 km 2 the landslide ratio in four sub watersheds of the kaoping watershed exceeded 6 5 analysis results indicate that the percentage of the downslope landslide areas is approximately 3 2 10 5 times higher than that of upslope landslide areas owing to serious scour of the riverside the power law exponent for rainfall induced landslide distribution during typhoon morakot is lower 1 3 1 4 than that for earthquake induced landslide distribution in the comparison of self organized criticality because the heavy rainfall induced many new landslides at different scales the hsiaolin landslide one of four giant landslides was a deep seated dip slope landslide with an area of 2 5 km 2 and a volume of 2 7 10 7 m 3 a portion of the sediment slid into the original valley and dammed the chishan river while another portion buried hsiaolin village based on the results the extremely high intensity and long duration of rainfall caused numerous landslides with different scales near the downslope region we recommend using the detailed topographic changes that occurred during the hsiaolin landslide to identify and prevent similar deep seated landslide disasters

unconventional pattern of reservoir facies distribution in epeiric successions lessons from an outcrop analog lower keuper germany this article presents 1 a process oriented description of an outcrop analog for epeiric successions 2 a discussion of fundamental characteristics of epeiric basin fills and 3 a generic depositional model which may be used for improved reservoir prediction in epeiric settings the case study focuses on the upper ladinian mixed siliciclastic carbonate lower keuper formation it is composed of storm generated tide generated and bioturbated facies paleogeographically the succession shows an unusual lateral energy zonation comprising a seaward low energy zone close to wave base an intermediate reservoir prone high energy zone within wave base and a landward low energy zone above wave base stratigraphically the lower keuper formation is subdivided into meter scale transgressive regressive cycles correlatable over distances of more than 500 km cycle boundaries are interpreted to be isochronous within the resulting chronostratigraphic framework facies distributions have been mapped out in three dimensions revealing that reservoir prone facies are most extensive in shoreline detached positions reservoir bodies are thin have sheetlike geometries but extend for several tens of kilometers and are stacked in an aggradational facies architecture additionally the reservoir prone facies is thicker developed in zones of stronger subsidence a few kilometers wide linked to underlying basement blocks resulting unconventional reservoir prediction strategies for similar shallow marine epeiric settings should target shoreline detached high energy facies belts that are preferentially developed within zones of stronger subsidence controlled by basement tectonics

effects of strength properties of discontinuities on the unstable lower slope in the chiu fen erh shan landslide taiwan abstract the chiu fen erh shan landslide was a huge dip slope avalanche triggered by the devastating chi chi earthquake in central taiwan in 1999 anomalous geomorphic precursors such as ground subsidence and thrust which are signs of slope instability were subsequently observed on the lower slope of the chiu fen erh shan landslide in november 2002 post failure behavior and affected area of the lower part of the landslide must be investigated to provide adequate countermeasures this study presents the results of the post failure behavior simulation of the lower slope of the chiu fen erh shan landslide using discontinuous deformation analysis dda the simulation results show that the surface rocks in the sliding mass move faster and further than the rocks at great depth the angle of internal friction is found to have a great influence on the failure process than does the cohesion the sliding rocks are accumulated in the depression in front of the toe of the landslide except under the conditions of very low internal friction the depression performs as a buffer zone when the lower slope fails

new insights on subsurface energy resources in the southern north sea barrin area the southern north sea basin area stretching from the uk to the netherlands has a rich hydrocarbon exploration and production history the past present and expected future hydrocarbon and geothermal exploration trends in this area are discussed for eight key lithostratigraphic intervals ranging from the lower carboniferous to cenozoic in the period between 2007 and 2017 a total of 95 new hydrocarbon fields were discovered particularly in upper carboniferous rotliegend and triassic reservoirs nineteen geothermal systems were discovered in the netherlands onshore mainly targeting aquifers in the rotliegend and upper jurassic lower cretaceous formations although the southern north sea basin area is mature in terms of hydrocarbon exploration it is shown that with existing and new geological insights additional energy resources are still being proven in new plays such as the basal upper rotliegend ruby discovery for natural gas and a new chalk play for oil it is predicted that hydrocarbon exploration in the southern north sea basin area will probably experience a slight growth in the coming decade before slowing down as the energy transition further matures geothermal exploration is expected to continue growing in the netherlands onshore as well as gain more momentum in the uk

frequency ratio model based landslide susceptibility mapping in lower mae chaem watershed northern thailand the purpose of this study is to produce a landslide susceptibility map for the lower mae chaem watershed northern thailand using a geographic information system gis and remotely sensed images for this purpose past landslide locations were identified from satellite images and aerial photographs accompanied by the field surveys to create a landslide inventory map ten landslide inducing factors were used in the susceptibility analysis elevation slope angle slope aspect lithology distance from lineament distance from drainage precipitation soil texture land use land cover lulc and ndvi the first eight factors were prepared from their associated database while lulc and ndvi maps were generated from landsat 5 tm images landslide susceptibility was analyzed and mapped using the frequency ratio fr model that determines the level of correlation between locations of past landslides and the chosen factors and describes it in terms of frequency ratio index finally the output map was validated using the area under the curve auc method where the success rate of 80 06 and the prediction rate of 84 82 were achieved the obtained map can be used to reduce landslide hazard and assist with proper planning of lulc in the future

sequence stratigraphy of carbonate evaporite basins models and application to the upper permian zechstein of northeast england and adjoining north sea the successions of carbonate evaporite basins which are periodically cut off from the world ocean are considered in terms of their sequence stratigraphy two basin types are distinguished those where incomplete drawdown takes place and those showing complete drawdown and wholesale basin desiccation it is argued that following relative sea level falls sequences begin with the evaporites precipitated as marginal lowstand gypsum wedges in the first basin type and as lowstand basin centre halite fills in the second the evaporites pass up into carbonate sediments which are mainly deposited on shallow water platforms around the basin during transgressive and highstand systems tracts the concepts and models developed are applied to the zechstein upper permian strata of northeast england and adjoining north sea seven sequences are proposed with some containing thin parasequences the sequence approach to carbonate evaporite basins which considers both basin margin and basin centre facies gives a more encompassing perspective of sedimentation than the traditional cycle concept with its emphasis on the basin centre

differential dissolution of a pleistocene reef in the ground water mixing zone of coastal yucatan mexico a geochemical explanation is provided for the extensive dissolution observed along the carbonate coast of the yucatan peninsula mexico mixing of fresh ground water with subterranean caribbean seawater generates a highly reactive geochemical zone that enhances aragonite and calcite dissolution and permits neomorphism of aragonite mixing zone dissolution caused by ground water discharge is a major geomorphic process in developing caves coves and crescent shaped beaches along the yucatan coast such dissolution has probably been a significant control on permeability and porosity distribution in carbonate rocks in the geologic record

landslide susceptibility mapping using rough sets and back propagation neural networks in the three gorges china in the three gorges of china there are frequent landslides and the potential risk of landslides is tremendous an efficient and accurate method of generating landslide susceptibility maps is very important to mitigate the loss of lives and properties caused by these landslides this paper presents landslide susceptibility mapping on the zigui badong of the three gorges using rough sets and back propagation neural networks bpnns landslide locations were obtained from a landslide inventory map supported by field surveys twenty two landslide related factors were extracted from the 1 10 000 scale topographic maps 1 50 000 scale geological maps landsat etm satellite images with a spatial resolution of 28 5 m and hj a satellite images with a spatial resolution of 30 m twelve key environmental factors were selected as independent variables using the rough set and correlation coefficient analysis including elevation slope profile curvature catchment aspect catchment height distance from drainage engineering rock group distance from faults slope structure land cover topographic wetness index and normalized difference vegetation index the initial three layered and four layered bpnn were trained and then used to map landslide susceptibility respectively to evaluate the models the susceptibility maps were validated by comparing with the existing landslide locations according to the area under the curve the four layered bpnn outperforms the other two models with the best accuracy of 91 53 approximately 91 37 of landslides were classified as high and very high landslide prone areas the validation results show sufficient agreement between the obtained susceptibility maps and the existing landslide locations

sequence stratigraphy and cyclic development of basal zechstein carbonate evaporite deposits with emphasis on zechstein 2 off platform carbonates upper permian northeast germany abstract although the basal zechstein is classically subdivided into two cycles z1 and z2 lower part it can alternatively be subdivided into three complete third order depositional sequences zs1 zs3 and the associated lowstand systems tract transgressive systems tract of a fourth sequence zs4 third and higher order sea level fluctuations influenced the depositional and diagenetic history of the carbonate evaporite alternations within the basal zechstein the main subject of the present study the zechstein 2 carbonate stassfurt carbonate or ca2 is interpreted to encompass both transgressive predominantly in slope and basinal settings and highstand systems tracts of zechstein sequence zs3 as well as part of the lowstand systems tract of the fourth zechstein sequence zs4 in northeastern germany hydrocarbon reservoirs of the ca2 developed along both northern and southern margins of the southern permian basin on top of the topography of the zechstein 1 cycle z1 this z1 topography resulted from deposition of the werra anhydrite a1 the highstand systems tract of the second zechstein sequence zs2 the northern ca2 carbonate platform is consistently narrow and fringed by coated grain and composite grain bars and shoals it is characterized by a steep fault controlled slope which precluded the formation of in situ shallow water grain dominated carbonates during relative sea level lowstands displaced shallow water coated grain and composite grain packstones wackestones may however occur as slope fan deposits turbidites in contrast the southern carbonate platform is wide tectonically dissected and fringed by grain dominated shallow water carbonates coated grain and composite grain bars and shoals zechstein 2 shallow water carbonates detectable by basal zechstein seismic anomalies also developed on pre existing topographical highs in off platform positions three depositional cycles ca2 cycles i ii and iii most probably reflecting high amplitude fourth order sea level fluctuations can be identified within the stassfurt carbonate our observations suggest that sea level variations possibly reflecting cyclicity in the milankovitch frequency band 0 1 0 4 ma and the pre zechstein topography pronounced during formation of the werra anhydrite were the most important factors in controlling the depositional as well as the diagenetic history of the zechstein 2 carbonate in off platform positions

predictive landslide susceptibility mapping using spatial information in the pechabun area of thailand for predictive landslide susceptibility mapping this study applied and verified probability model the frequency ratio and statistical model logistic regression at pechabun thailand using a geographic information system gis and remote sensing landslide locations were identified in the study area from interpretation of aerial photographs and field surveys and maps of the topography geology and land cover were constructed to spatial database the factors that influence landslide occurrence such as slope gradient slope aspect and curvature of topography and distance from drainage were calculated from the topographic database lithology and distance from fault were extracted and calculated from the geology database land cover was classified from landsat tm satellite image the frequency ratio and logistic regression coefficient were overlaid for landslide susceptibility mapping as each factor s ratings then the landslide susceptibility map was verified and compared using the existing landslide location as the verification results the frequency ratio model showed 76 39 and logistic regression model showed 70 42 in prediction accuracy the method can be used to reduce hazards associated with landslides and to plan land cover

twenty ninth canadian geotechnical colloquium the role of advanced numerical methods and geotechnical field measurements in understanding complex deep seated rock slope failure mechanisms the underlying complexity associated with deep seated rock slope stability problems usually restricts their treatment to phenomenological studies that are largely descriptive and qualitative quant

probabilistic landslide susceptibility and factor effect analysis the susceptibility of landslides and the effect of landslide related factors at penang in malaysia using the geographic information system gis and remote sensing data have been evaluated landslide locations were identified in the study area from interpretation of aerial photographs and from field surveys topographical and geological data and satellite images were collected processed and constructed into a spatial database using gis and image processing the factors chosen that influence landslide occurrence were topographic slope topographic aspect topographic curvature and distance from drainage all from the topographic database lithology and distance from lineament taken from the geologic database land use from landsat thermatic mapper tm satellite images and the vegetation index value from spot hrv high resolution visible satellite images landslide hazardous areas were analyzed and mapped using the landslide occurrence factors employing the probability frequency ratio method using the all factors to assess the effect of these factors each factor was excluded from the analysis and its effect verified using the landslide location data as a result all factors had relatively positive effects except lithology on the landslide susceptibility maps in the study area

pre processing algorithms and landslide modelling on remotely sensed dems abstract terrain analysis applications using remotely sensed digital elevation models dems nowadays easily available permit to quantify several river basin morphologic and hydrologic properties e g slope aspect curvature flow path lengths and indirect hydrogeomorphic indices e g specific upslope area topographic wetness index able to characterize the physical processes governing the landscape evolution e g surface saturation runoff erosion deposition such dems often contain artifacts and the automated hydrogeomorphic characterization of the watershed is influenced by terrain analysis procedures consisting in artificial depression pit and flat area treatment approaches combined with flow direction methods in shallow landslide deterministic models when applied using topographic dataset at medium scale e g 30 m of resolution the choice of the most suitable dem processing procedure is not trivial and can influence model results this also affects the selection of most critical areas for further finer resolution studies or for the implementation of countermeasures aiming to landslide risk mitigation in this paper such issue is investigated using as topographic input the aster dems and comparing two different combinations of dem correction and flow routing schemes the study areas comprise ten catchments in italy for which hydrogeomorphic processes are significant aims of this paper are 1 to introduce a parameter estimation procedure for the physically based dem correction method pem4pit physical erosion model for pit removal 2 to investigate the influence of different terrain analysis procedures on results of the slope stability model shalstab shallow landsliding stability using remotely sensed aster dems 3 trying to assess which of terrain analysis methods is more appropriate for describing terrain instability

determining landslide susceptibility in central taiwan from rainfall and six site factors using the analytical hierarchy process method this work provides a landslide susceptibility assessment model for rainfall induced landslides in central taiwan based on the analytical hierarchy process method the model considers rainfall and six site factors including slope geology vegetation soil moisture road development and historical landslides the rainfall factor consists of 10 day antecedent rainfall and total rainfall during a rainfall event landslide susceptibility values are calculated for both before and after the beginning of a rainfall event the 175 landslide cases with detailed field surveys are used to determine a landslide susceptibility threshold value of 9 0 when a landslide susceptibility assessment value exceeds the threshold value slope failure is likely to occur three zones with different landslide susceptibility levels below slightly above and far above the threshold are identified the 9149 landslides caused by typhoon toraji in central taiwan are utilized to validate the study s result approximately 0 2 0 4 and 15 3 of the typhoon caused landslides are located in the three landslide susceptibility zones respectively three villages with 6 6 0 4 and 4 9 of the landslides respectively are used to validate the accuracy of the landslide susceptibility map and analyze the main causes of landslides the landslide susceptibility assessment model can be used to evaluate susceptibility relative to accumulated rainfall and is useful as an early warning and landslide monitoring tool

the hydrological setting occurrence and significance of gypsum in late quaternary salt lakes in south australia well exposed often laminated gypsum sequences occur in many quarternary salt lakes in southern south australia the gypsum in the salt lakes is classified by increasing grain size into gypsite gypsarenite and selenite the salt lakes are classified by age and hydrological setting into coastal salinas which are holocene sea water fed groundwater lakes and continental playas which are late pleistocene endorheic basins a study of the relationships between coastal salina hydrology and the associated gypsum deposition has shown the different types of gypsum form under distinct hydrological regimes as the hydrology above a coastal salina depositional surface changes through time so does the type of gypsum deposited application of a gypsum depositional model derived from a study of the coastal salina gypsum to those portions of a continental playa gypsum unit where deposition is no longer occurring confirms the applicability of the model to non salina gypsum deposits

influence of thermomechanics in the catastrophic collapse of planar landslides frictional heating has long been considered a mechanism responsible for the high velocities and long run out of some large scale landslides in this work a landslide model is presented applicable

upper permian zechstein supergroup carbonate evaporite platform palaeomorphology in the uk southern north sea abstract seismic interpretation geological mapping and depth conversion of the zechstein supergroup z2 cycle using high quality well calibrated three dimensional 3 d seismic has revealed the complex palaeomorphology of a deeply buried ancient carbonate shelf margin on the southwestern margin of the southern permian basin the new mapping shows that the margin comprises a series of corrugated embayments and promontories which extend up to 5 km 3 mi into the basin and locally have a palaeobathymetric relief of 200 m 650 ft well calibration across the margin demonstrates a strongly bipartite lateral thickness distribution between a high velocity anhydrite dominated shelf and a lower velocity halite dominated basin strong lateral and vertical velocity variations in the upper permian zechstein supergroup are known to have major impacts upon seismic imaging and depth conversion in the spb the resulting uncertainty remains one of the major challenges when interpreting and assessing the prospectivity of the underlying upper permian rotliegend group leman sandstone formation reservoirs in the uk southern north sea an understanding of the zechstein shelf edge s 3 d physiography and its velocity variation has implications for the delineation of traps containing the prospective reservoirs that lie below recognition of the complexity and effects of this shelf margin contributed to the recent juliet discovery whose position outside of the presently defined rotliegend group play fairway suggests that prospectivity is more extensive along the basin margin than previously thought as such the work provides a means by which to identify and delineate new structures and extend the life of this mature yet prolific gas province

3d numerical modeling using smoothed particle hydrodynamics of flow like landslide propagation triggered by the 2008 wenchuan earthquake abstract the extremely strong wenchuan earthquake triggered thousands of landslides in sichuan province china flow like landslides such as the tangjiashan wangjiayan and donghekou landslides were among the most destructive causing many casualties and serious economic damage it is therefore important to identify the flow mechanisms and investigate the specific characteristics of these flow like landslides this paper presents a three dimensional model based on smoothed particle hydrodynamics sph to simulate rapid landslide motion across 3d terrain the navier stokes equations in a cfd framework are used as governing equations and artificial viscosity is incorporated into the pressure terms in the momentum equation to dissipate energy to avoid numerical oscillation and particle penetration thus improving the stability of the numerical results a non newtonian fluid model the bingham model has proven suitable for describing the relationship between the shear strain rate and the shear stress in highly deformed soil materials in the proposed model it is used as the constitutive model to describe the fluidization characteristics of flow like landslides combined with the mohr coulomb yield criterion the model incorporates a no slip boundary condition to consider the effect of a solid boundary on slope movement ghost particles are created and assigned an artificial velocity the viscous force caused by the solid boundary is calculated using the relative velocities between the fluid and the boundary particles open multiprocessing openmp an api for multi platform shared memory parallel programming is used to improve the efficiency of the sph code running to show the validity of the proposed approach a benchmark problem of 3d dam break was simulated the calculated distances of the surge front at different times agree well with the test results numerical modeling of the propagation of the tangjiashan wangjiayan and donghekou landslides was performed by the application of sph models to real flow like landslides the whole flow processes of these flow like landslides across the 3d terrain are represented the landslides change direction split or join in and spread or contract in their flow path in response to the local topography time history curves of the velocity and displacement were obtained to analyze the movement characteristics of the landslide mass the shapes of the deposition zones after slide occurrence were investigated comparisons of the sph simulated geometry and the surveyed landslide configurations for the tangjiashan wangjiayan and donghekou landslides were conducted and show a high degree of similarity this indicates that the proposed 3d sph model can accurately represent the evolution of the final slide shape the prediction of the fluidization characteristics of earthquake induced flow like landslides can notably reduce sudden loss of life as it provides a means for mapping hazardous areas for estimating the hazard intensity and for identification and design of appropriate protective measures

impacts of the chi chi earthquake on subsequent rainfall induced landslides in central taiwan abstract the influence of the chi chi earthquake on subsequent rainfall induced landslides was evaluated by comparing the occurrence of landslides in the choushui river watershed through eight spot images that covered the period from 1996 to 2001 the chi chi earthquake not only triggered serious coseismic landslides itself but also extensively disturbed surface strata around the epicentral area after surface strata have been highly disturbed heavy rainfalls in 2000 and 2001 have triggered more landslides than the earthquake itself compared with the data obtained from images before the earthquake it is obvious that the density of rainfall induced landslides increased significantly after the earthquake and the places where landslides occurred changed as well although typhoon herb in 1996 brought more precipitation than typhoon toraji in 2001 only 9 77 km 2 landslides were induced by herb while 48 8 km 2 landslides almost five times larger than those caused by herb were triggered by toraji besides landslides induced by herb were mainly distributed in mid slope areas with slopes of 20 30 after the chi chi earthquake the rainfall induced landslides occurred mainly in places with slopes between 40 and 50

landslide susceptibility assessment in the izmir west anatolia turkey city center and its near vicinity by the logistic regression method a landslide susceptibility assessment for izmir city western turkey which is the third biggest city of turkey was performed by a logistic regression method a database of landslide characteristics was prepared using detailed field surveys the major landslides in the study area are generally observed in the field dominated by weathered volcanics and 39 63 of the total landslide area is in this unit the parameters of lithology slope gradient slope aspect distance to drainage distance to roads and distance to fault lines were used as variables in the logistic regression analysis the effect of each parameter on landslide occurrence was assessed from the corresponding coefficients that appear in the logistic regression function on the basis of the obtained coefficients lithology plays the most important role in determining landslide occurrence and distribution slope gradient has a more significant effect than the other geomorphological parameters such as slope aspect and distance to drainage using a predicted map of probability the study area was classified into five categories of landslide susceptibility very low low moderate high and very high whereas 49 65 of the total study area has very low susceptibility very high susceptibility zones make up 11 69 of the area

dedolomitization review and case study of uncommon mesogenetic formation conditions abstract dedolomitization converts a dolomite into a calcite and conventionally is interpreted to form in an eogenetic or telogenetic diagenetic environment where meteoric water dissolves evaporites to supply excess calcium hydrologic connectivity between a dolostone and the surface water may then lead to a dedolomitized interval often times being a diagnostic indicator for an erosional unconformity subaerial exposure and or karst in contrast to the classic models we present a case study for pervasive burial dedolomitization unrelated to meteoric fluids dedolomitization of the zechstein 2 carbonate ca2 gas reservoir in nw germany is strongly altering reservoir quality on a regional scale the ca2 shows a textbook correlation between reservoir quality and mineralogy petrographic analyses show that approximately 80 of all observed calcite reveal a dedolomite microtexture causing a reduction of average matrix porosity by 5 to 10 compared to the dolomite dedolomite follows initial layering and abundantly forms massive concretions which are surrounded by compaction related curvature of the depositional layering in the dolomite host rock such an early burial timing is supported by a slight burial related shift of 3 18o and 1 13c towards lighter values in the dedolomites compared to dolomite an exceptionally large amount of calcium rich fluids must have been mobilized to account for 50 of the ca2 rock volume to be dedolomitized however core fabrics related to meteoric diagenesis such as karst fabrics or typical fresh water stable isotope signatures have been observed neither in the ca2 nor in over and underlying anhydrite beds instead excess calcium likely comes from gypsum to anhydrite conversion and pressure solution within over and underlying anhydrites an influx of strontium rich waters from the anhydrite beds is indicated by up to 5 times higher strontium contents measured in dedolomite fabrics compared to their dolomite host rock homogenization temperatures between 51 and 56 c measured in some early fluid inclusions in dedolomite textures further exclude a pristine meteoric water input and suggest fluid entrapment in a burial depth range of 900 to 1400 m comparing these results with literature data furthermore indicates that mesogenetic dedolomite is either volumetrically underestimated in other carbonate evaporite settings or formed under unique diagenetic conditions across the southern permian basin during zechstein times

non catastrophic landslides induced by the mw 7 6 chi chi earthquake in central taiwan as revealed by piv analysis abstract the chi chi earthquake occurred in the western foothills of central taiwan which triggered coseismic and catastrophic chiufengershan dip slope landslides tsaoling rockslides and surface stripping of the jiujiufeng area after a few days of the chi chi event the hongtsaiping area in central taiwan was reported to have several meters of slide in a small scale area the reported landslides are dissimilar to the catastrophic events to better understand the characteristics of such non catastrophic and unobvious landslide we try to characterize in detail the sliding directions their magnitudes and region of the landslide we analyzed three orthorectified aerial photographs of the hongtsaiping area which were taken in 1998 06 13 1999 11 18 and 2002 10 26 using the particle image velocimetry piv technique through the method we correlated the image pixels of the two aerial photographs in order to derive the displacement vector field the results of the piv analysis have helped us not only find the areas where sliding had happened but also evaluate the azimuth and magnitudes of the sliding event the piv analysis in the hongtsaiping area covers a dimension of about 3228 2448 pixels in an area of about 1 2 km2 our results show that the maximum horizontal displacement of the landslide is about 24 m towards nw in the study area this unobvious but wide coverage landslide may need further investigation in mechanisms combining with available or new geological data

dynamic response of a physical anti dip rock slope model revealed by shaking table tests abstract the anti dip rock slopes are common geological features in taiwan and the failure of this type of rock slope is prone to be triggered by seismic loads thus it is important to investigate its dynamic behavior for further mitigation and prevention the response of an anti dip slope to an earthquake was modeled in this study by conducting a series of shaking table tests to determine the stability and the failure process for an anti dip slope under different seismic loads a high speed camera was used for noncontact measurement and the captured images were analyzed to identify block sliding rotation and toppling the results demonstrated that 1 an anti dip slope with a low block inclination angle p has better resistance to seismic loads 2 for the same peak ground acceleration pga the lower the frequency the greater is the extent of block sliding and toppling failure 3 at a constant frequency the greater the pga the greater is the extent of block sliding and toppling failure 4 when an anti dip slope is subjected to a seismic load the blocks with the smallest aspect ratio start to move first and the order of force transmission between blocks depends on the aspect ratio x yn 5 the noncontact measurement and image analysis indicated a maximum error of only 5 for block displacement in conclusion this study determined the sequence of the movement of the blocks in an anti dip rock slope model subjected to seismic loading the results showed that the slenderest block defines the stability of the models the models could be used as benchmarks for numerical approaches aimed at mitigation of anti dip slope failures

analysis of the chiufengershan landslide triggered by the 1999 chi chi earthquake in taiwan abstract a disastrous earthquake rocked taiwan on september 21 1999 with magnitude m l 7 3 and an epicenter near the small town of chi chi in central taiwan the chi chi earthquake triggered landslide on the dip slope at the chiufengershan in this study a review of the topography and geology of this area was followed by field investigations laboratory testing was applied to understand the geomaterial composing the slope then based on a series of limit equilibrium analyses the failure mechanism of this landslide and the risk of the residual slope were studied according to the stability analyses the pre quake slope is quite stable with factor of safety of 1 77 dry to 1 35 full groundwater level explaining why there is no written record of a landslide here for the past 100 years in contrast a back analysis shows that the chi chi earthquake induced dynamic loading is far more than the dip slope can sustain due in part to the short distance to the epicenter a monte carlo type probability analysis suggests that the residual slope is more dangerous than the pre quake slope and needs more attention

quantitative landslide susceptibility mapping at pemalang area indonesia for quantitative landslide susceptibility mapping this study applied and verified a frequency ratio logistic regression and artificial neural network models to pemalang area indonesia using a geographic information system gis landslide locations were identified in the study area from interpretation of aerial photographs satellite imagery and field surveys a spatial database was constructed from topographic and geological maps the factors that influence landslide occurrence such as slope gradient slope aspect curvature of topography and distance from stream were calculated from the topographic database lithology was extracted and calculated from geologic database using these factors landslide susceptibility indexes were calculated by frequency ratio logistic regression and artificial neural network models then the landslide susceptibility maps were verified and compared with known landslide locations the logistic regression model accuracy 87 36 had higher prediction accuracy than the frequency ratio 85 60 and artificial neural network 81 70 models the models can be used to reduce hazards associated with landslides and to land use planning

analysis of landsliding by earthquake shaking using a block on slope thermo mechanical model example of jiufengershan landslide central taiwan the jiufengershan rock and soil avalanche is one of the largest landslides triggered by the chi chi taiwan earthquake september 21 1999 in order to study landslide triggering and propagation by seismic shaking we propose a method that combines features of the classic newmark approach with mechanical relations involving mohr coulomb failure criteria pore water pressure and shear heating during the sliding process the effective shear strength is affected by shear heating and by pore pressure variations during the sliding process the shaking process was simulated using strong motion accelerograms of the three nearest free field stations which surrounded the landslide the initiation and propagation of earthquake induced landslides are mainly controlled by the peak and residual shear strengths respectively the increase in temperature in the shear zone increases the pore water pressure and weakens the shear strength rock avalanches are generated when mechanical parameters achieve critical threshold values such that the residual shear strength is less than the tangential projection of body forces

validation of an artificial neural network model for landslide susceptibility mapping the aim of this study was to validate an artificial neural network model at youngin janghung and boeun korea using the geographic information system gis the factors that influence landslide occurrence such as the slope aspect curvature and geomorphology of topography the type material drainage and effective thickness of soil the type diameter age and density of forest distance from lineament and land cover were either calculated or extracted from the spatial database and landsat tm satellite images landslide susceptibility was analyzed using the landslide occurrence factors provided by the artificial neural network model the landslide susceptibility analysis results were validated and cross validated using the landslide locations as study areas for this purpose weights for each study area were calculated by the artificial neural network model among the nine cases the best accuracy 81 36 was obtained in the case of the boeun based janghung weight whereas the janghung based youngin weight showed the worst accuracy 71 72

formation of south facing bald mudstone slopes in southwestern taiwan abstract in the southwestern part of taiwan most foothills are covered by mudstones the mudstone formed during miocene to pliocene and pleistocene is a young and weak sedimentary rock when subjected to water slaking of the mudstone can easily take place and in dry seasons severe shrinkage can occur thus erosion of mudstone slopes is easily induced by rainfalls heavily eroded natural mudstone slopes in southwestern taiwan frequently become bald i e not covered by any plants or bushes and are very susceptible to geologic damages such as mudflow and slope failure one interesting observation of the mudstone slopes in southwestern taiwan is that most of the bald slopes are south facing the causes of this directional variation are thoroughly examined in this paper it is concluded that solar radiation rather than the direction of typhoons is the main reason for forming bald slopes in the south facing direction

dip slope mapping of sedimentary terrain using polygon auto tracing and airborne lidar topographic data abstract dip slope mapping is a fundamental task for landslide investigation and mitigation however most dip slope mapping methods involve visual interpretations and manual processes that are inevitably subjective and time consuming the advent of high resolution digital elevation models dem and increases in computing power have provided opportunities to improve the dip slope mapping process this study proposes a polygon auto tracing method for generating dip slope maps based on airborne light detection and ranging lidar data and a customized spatial analysis toolset developed in python this method requires the input of strata boundaries produced for sedimentary terrain based on 2 m resolution lidar dems the method begins by deriving the raster layer of the dip direction of the bedding and it then executes a series of raster calculations among the three raster layers slope aspect and dip direction to extract the dip slope raster cells using the clustering pattern of the dip slope raster cells we implement the point density analysis tool to determine the dip slope areas the arcgis modelbuilder platform is used to lay out an automated workflow for the proposed polygon auto tracing method using the customized toolset for demonstration purposes we successfully mapped 298 dip slopes in the study area which frequently experiences dip slope landslides and is located in the sedimentary terrain of northern taiwan the dip slope mapping results were compared and validated against two government funded visually interpreted dip slope maps our dip slope mapping results were also used in a daylight analysis along major freeways to identify potential locations of daylighted dip slopes

landslide susceptibility mapping for a landslide prone area findikli ne of turkey by likelihood frequency ratio and weighted linear combination models landslides are very common natural problems in the black sea region of turkey due to the steep topography improper use of land cover and adverse climatic conditions for landslides in the western part of region many studies have been carried out especially in the last decade for landslide susceptibility mapping using different evaluation methods such as deterministic approach landslide distribution qualitative statistical and distribution free analyses the purpose of this study is to produce landslide susceptibility maps of a landslide prone area findikli district rize located at the eastern part of the black sea region of turkey by likelihood frequency ratio lrm model and weighted linear combination wlc model and to compare the results obtained for this purpose landslide inventory map of the area were prepared for the years of 1983 and 1995 by detailed field surveys and aerial photography studies slope angle slope aspect lithology distance from drainage lines distance from roads and the land cover of the study area are considered as the landslide conditioning parameters the differences between the susceptibility maps derived by the lrm and the wlc models are relatively minor when broad based classifications are taken into account however the wlc map showed more details but the other map produced by lrm model produced weak results the reason for this result is considered to be the fact that the majority of pixels in the lrm map have high values than the wlc derived susceptibility map in order to validate the two susceptibility maps both of them were compared with the landslide inventory map although the landslides do not exist in the very high susceptibility class of the both maps 79 of the landslides fall into the high and very high susceptibility zones of the wlc map while this is 49 for the lrm map this shows that the wlc model exhibited higher performance than the lrm model

carbonate dissolution in a modern mixing zone the potential for dissolution of calcite and aragonite and precipitation of dolomite by the mixing of fresh and saline ground waters has been demonstrated theoretically1 3 although geologists have used these processes in the explanation of the diagenesis of recent4 7 and ancient8 12 carbonates there has been only limited investigation of the geochemical processes of modern mixing zones13 14 here we report the results of chemical and rock profiling through a modern mixing zone on andros island in the bahamas our results demonstrate undersaturation of the waters in the mixing zone with respect to aragonite and calcite and corresponding pervasive dissolution of the carbonate rocks at this level undersaturation is significantly enhanced by bacterial processes which are also responsible for precipitation of an iron rich crust despite chemical supersaturation precipitation of dolomite was not observed thereby casting some doubt on the mixing zone model of dolomitization

constraining regional paleo peak ground acceleration from back analysis of prehistoric landslides example from sea of galilee dead sea transform article i nfo accurate estimation of expected peak ground acceleration pga in seismically active regions is a challenging task the best way to estimate quantitatively expected pga is by investigating instrumental data of past strong earthquakes in a given area in some regions of the world however recorded data are scarce and if they exist they are typically available only since the late 19th century as such they are hardly representative of the true seismicity in the studied region we propose here an analytical approach to constrain the lower threshold of paleoseismic pga on the basis of back analysis of old landslides to perform the analysis we need a mapped landslide with geomorphic features that have been preserved in the field the slip surface a good reconstruction of the slope geometry and ground water level prior to failure and the mechanical properties of the sheared material we perform static and pseudo static limit equilibrium analyses using standard solution procedures to obtain lower bounds of paleoseismic pga back analyses of three different landslides around the sea of galilee sog return similar results that range between 0 15 and 0 5 g thus constraining the threshold paleoseismic pga range for this region the analytically inferred regional pga is supported by results of an independent numerical analysis of toppled columns in a nearby byzantine church using results from a recent paleoseismic trenching study performed on one of the studied landslides and a modified attenuation relationship for the study area we localize the loci of moment magnitude mw 7 0 earthquakes that can explain the studied failures along the boundaries of the sog and find that they coincide with traces of the eastern and western margin faults of the dead sea transform the temporal relationships between the observed failures are discussed on the basis of dated colluvial sediments geomorphologic constraints and archeological evidence

geological and morphological study of the jiufengershan landslide triggered by the chi chi taiwan earthquake the jiufengershan rock and soil avalanche is one of the largest landslides triggered by the chi chi earthquake taiwan 1999 the landslide destabilized the western limb of the taanshan syncline along a weak stratigraphic layer it involved a flatiron remnant which was almost entirely mobilized during the earthquake the avalanche was slowed down by ns trending ridges located downstream along the jiutsaihu creek the landslide affected a 60 m thick and 1 5 km long sedimentary pile composed of shales and sandstones which dip 228se toward a transverse valley the triggering mechanism and the sliding process were analyzed by means of geological and morphological data from aerial photographs and observed in the field a high resolution airborne light detection and ranging lidar image taken 2 5 years after the landslide allows the identification of morphological structures along the sliding surface and the landslide accumulation the sliding surface shows several deformation structures such as fault scarps and folds these structures are interpreted in terms of basal shear stresses created during the avalanche three major joint sets were identified at the sliding surface the isopach map of the landslide was calculated from the comparison between elevation models before and after the earthquake the coseismic volume of mobilized material and landslide deposit data are 4210 6 m 3 and 5010 6 m 3 respectively the geometry of the landslide accumulation in the field has an irregular star shape the morphology of the deposit area shows a sequence of smooth reliefs and depressions that contrast with the neighboring ridges d 2005 elsevier b v all rights reserved

probabilistic landslide susceptibility mapping in the lai chau province of vietnam focus on the relationship between tectonic fractures and landslides this study evaluates the susceptibility of landslides in the lai chau province of vietnam using geographic information system gis and remote sensing data to focus on the relationship between tectonic fractures and landslides landslide locations were identified from aerial photographs and field surveys topographic geological data and satellite images were collected processed and constructed into a spatial database using gis data and image processing techniques a scheme of the tectonic fracturing of crust in the lai chau region was established lai chau was identified as a region with many crustal fractures where the grade of tectonic fracture is closely related to landslide occurrence the influencing factors of landslide occurrence were distance from a tectonic fracture slope aspect curvature soil and vegetative land cover landslide prone areas were analyzed and mapped using the landslide occurrence factors employing the probability frequency ratio model the results of the analysis were verified using landslide location data and showed 83 47 prediction accuracy that emphasized a strong relationship between the susceptibility map and the existing landslide location data the results of this study can form a basis stable development and land use planning for the region

the kuroshio bifurcation associated with islands at the luzon strait based upon a suite of satellite and hydrology data along with numerical model simulations the kuroshio is found to be separated into two branches the two branches are located on the western and eastern sides of the batanes islands the western branch which is the main branch of the kuroshio is estimated to carry roughly 68 of the transport while the eastern branch which has not been reported before carries the remainder both branches bring warmer water northward producing two separate warm tongues east of the luzon strait the western warm tongue has an obvious seasonal variation due to the seasonal variation of the kuroshio in the northern luzon strait while the eastern warm tongue is associated with pacific mesoscale eddies as an anticyclonic a cyclonic eddy approaches the batanes islands from the east the eastern branch of the kuroshio is strongly intensified weakened and a more less pronounced warm tongue is induced consequently interannual variability of pacific mesoscale eddies affects the strength of the eastern branch

evolution of the nw margin of the north permian basin uk north sea mapping of depositional zones within the zechstein supergroup using semi regional 2d and 3dseismic data constrains the geological evolution of the northwestern margin of the north permian basinin uk offshore quadrants 14 15 19 20 and 21 four depositional zones are identified on the basis of mappable seismic facies which are assumed to vary with halite content well control characterizes the most reflective seismic facies as an interbedded carbonate and anhydrite shelf succession which grades laterally through clastic rich sequences to the least reflective a thick halite basinal equivalent the trendsof the depositional zones illustrate the geometry of the north permian basin and may have been locally controlled by basement lineaments within the north permian basin a n s trending axis devil s hole high characterized by thick reflective facies separates the central north sea from the forth approaches basin basement fault blocks control facies type and thickness along the northwest margin of the north permian basin in the moray firth area permian tilt of the zechstein shelf related to regional flexure played a role in precipitating gravity driven tectonics within the seismically reflective facies on the east flank of the devil s hole high this permian phase of salt tectonics resulted in numerous intra zechstein structures which can be interpreted as rafted and folded zones of interbedded halite carbonate sulphate and clastics the rafts initially slid downdip towards the main halite basin then their evolution became dominated by differential subsidence of the interbeds which forced salt layers into adjacent passive diapirs this episode predates deposition of the triassic smith bank shales which rest upon the zechstein with local angular unconformity the spatial distribution of zechstein facies influenced the tectonostratigraphy of the triassic jurassic and cretaceous systems boundaries between zechstein facies correspond to the limit of triassic halokinesis on the west central shelf and the limit of detachment of jurassic and lower cretaceous thin skinned tectonics in moray firth half graben

regional extraction of flexural toppled slopes in epicentral regions of subduction earthquakes along the nankai trough using dems in the epicentral region of subduction earthquakes large scale landslides are triggered by strong shaking of slopes weakened by flexural toppling the distribution of flexural toppled slopes is the primary information for predicting and mitigating landslide damage beforehand this study proposes and tests a simple algorithm for extracting flexural toppled slopes on a regional basis from a 10 m resolution digital elevation model by windows of two sizes local relief is extracted with a large window 200 200 pixels and microtopography is extracted with a small window 3 3 pixels the algorithm was derived from the region of the kanagi kuzure landslide in shikoku and tested at aka kuzure landslide in honshu in japan both areas are underlain by strongly tilted sedimentary rocks in epicentral regions of subduction earthquakes along the nankai trough

diagenesis of nearshore carbonate rocks in the sprotbrough member of the cadeby magnesian limestone formation upper permian of eastern england

geometry and quaternary kinematics of fold and thrust units of southwestern taiwan structural and paleostress analyses provide new insights into the quaternary kinematics of the outermost fold and thrust units of southwestern taiwan foothills the frontal folds are interpreted as fault related folds and their tectonic evolution through space and time is tightly constrained fold development is correlated with reef building on top of the anticlines moreover we provide field evidence that nw se fault zones oblique to the structural grain of the belt probably acted as transfer fault zones during the the quaternary fold thrust emplacement two successive quaternary stress regimes are evidenced in southwestern taiwan a nw se compression followed by a recent nearly e w compression the latter shows an along strike change from pure e w contraction to the north to perpendicular n s extension in the south this southward decrease in n s confinement probably represents the on land signature of the incipient quaternary tectonic escape predicted by analogue and numerical modelling and evidenced at present day by global positioning system data

discrete element simulation of the jiufengershan rock and soil avalanche triggered by the 1999 chi chi earthquake taiwan we present contact dynamics discrete element simulations of the earthquake triggered jiufengershan avalanche which mobilized a 60 m thick 1 5 km long sedimentary layer dipping similar to 22 degrees se toward a valley the dynamic behavior of the avalanche is simulated under different assumptions about rock behavior water table height and boundary shear strength additionally seismic shaking is introduced using strong motion records from nearby stations we assume that seismic shaking generates shearing and frictional heating along the surface of rupture which in turn may induce dynamic weakening and avalanche triggering a simple slip weakening criterion was adopted to simulate shear strength drop along the rupture surface we investigate the mechanical processes occurring during triggering and propagation of an avalanche mobilizing shallowly dipping layers incipient deformation forms a pop up structure at the toe of the dip slope as the avalanche propagates the pop up deforms into an overturned fold which overrides the surface of separation along a decollement simultaneously uphill layers slide at high velocity 125 km h and are folded and disrupted as they reach the toe of the dip slope the avalanche foot forms a wedge that is pushed forward as deformed rocks accrete at its rear we simulated five cross sections across the jiufengershan avalanche which differ in the geometry of the surface of separation topographic and simulated surface profiles are similar the friction coefficient at the surface of separation determined from back analysis is abnormally low mu ss 0 2 possibly due to lubrication by liquefied soils the granular deposits of simulated earthquake and rain triggered avalanches are similar

landslide susceptibility mapping in the damrei romel area cambodia using frequency ratio and logistic regression models this study applied tested and compared a probability model a frequency ratio and statistical model a logistic regression to damre romel area cambodia using a geographic information system for landslide susceptibility mapping landslide locations were identified in the study area from interpretation of aerial photographs and field surveys and a spatial database was constructed from topographic maps geology and land cover the factors that influence landslide occurrence such as slope aspect curvature and distance from drainage were calculated from the topographic database lithology and distance from lineament were extracted and calculated from the geology database land cover was classified from landsat tm satellite imagery the relationship between the factors and the landslides was calculated using frequency ratio and logistic regression models the relationships frequency ratio and logistic regression coefficient were overlaid to make landslide susceptibility map then the landslide susceptibility map was compared with known landslide locations and tested as the result the frequency ratio model 86 97 and the logistic regression 86 37 had high and similar prediction accuracy the landslide susceptibility map can be used to reduce hazards associated with landslides and to land cover planning

dynamic discrete analysis of an earthquake induced large scale landslide abstract the chiu fen erh shan landslide estimated to have a volume of 36 million cubic meters was triggered by the m w 7 6 taiwan chi chi earthquake of 1999 the debris covered an area of 1 95 km 2 and claimed 36 lives during the sliding the landslide mass disintegrated with its debris acquiring high speeds to reach over 1 km of travel distance the main objectives of the study were to investigate if it was possible to numerically model the landslide progression including slope disintegration and to reproduce the post failure configuration toward these goals the study employed a discrete element method called discontinuous deformation analysis for the dynamic analysis by incorporating the spacing and orientation information of the joints and bedding planes the slope was modeled as an assemblage of discrete deformable blocks horizontal and vertical ground motions were simultaneously applied the near field digital strong records were affected by the large uplift of the hanging wall of the reverse thrust fault and corrections were made to address this issue the study showed that the methodology adopted was able to capture essential characteristics of the landslide and gave a post failure configuration resembling that observed in the field