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

gis based landslide susceptibility mapping using bivariate statistical analysis in devrek zonguldak turkey devrek town with increasing population is located in a hillslope area where some landslides exist therefore landslide susceptibility map of the area is required the purpose of this study was to generate a landslide susceptibility map using a bivariate statistical index and evaluate and compare the results of the statistical analysis conducted with three different approaches in seed cell concept resulting in different data sets in geographical information systems gis based landslide susceptibility mapping applied to the devrek region the data sets are created from the seed cells of a crowns and flanks b only crowns and c only flanks of the landslides by using ten different causative parameters of the study area to increase the data dependency of the analysis all parameter maps are classified into equal frequency classes based directly on the percentile divisions of each corresponding seed cell data set the resultant maps of the landslide susceptibility analysis indicate that all data sets produce fairly acceptable results in each data set analysis elevation lithology slope aspect and drainage density parameters are found to be the most contributing factors in landslide occurrences the results of the three data sets are compared using seed cell area indexes scai this comparison shows that the crown data set produces the most accurate and successful landslide susceptibility map of the study area

landslide hazard evaluation and zonation mapping in mountainous terrain abstract landslide hazard zonation lhz maps are of great help to planners and field engineers for selecting suitable locations to implement development schemes in mountainous terrain as well as for adopting appropriate mitigation measures in unstable hazard prone areas a new quantitative approach has been evolved based on major causative factors of slope instability a case study of landslide hazard zonation in the himalaya adopting a landslide hazard evaluation factor lhef rating scheme has been presented

evaluation of prediction capability of the artificial neural networks for mapping landslide susceptibility in the turbolo river catchment northern calabria italy abstract landslides are one of the most widespread natural hazards that cause damage to both property and life every year and therefore the spatial distribution of the landslide susceptibility is necessary for planning future developmental activities in this paper the artificial neural network ann technique is tested for developing a landslide susceptibility map in turbolo river catchment north calabria south italy landslides were mapped through air photo interpretation and field surveys by identifying both the landslide depletion zones dzs and accumulation zones azs and relevant geo environmental thematic layers pertaining to landslide predisposing factors were generated using air photo interpretation field surveys and geographic information system gis tools ten predisposing factors were related to the occurrence of landslide lithology faults land use drainage network and a series of topographic factors elevation slope aspect plan curvature topographic wetness index twi and stream power index spi in order to evaluate and validate landslide susceptibility the dzs were divided in two groups using a random partition strategy the first group training set was used to prepare the susceptibility map employing a back propagation learning algorithm in the idrisi taiga software the second group testing set was used to validate the landslide susceptibility model using the confusion matrix and the receiver operating characteristic roc curve the susceptibility map was classified into five susceptibility classes very low low moderate high and very high about 46 of the study area falls in high to very high susceptible classes and most of the dzs mapped 87 3 occur in the same classes the validation results showed satisfactory agreement between the susceptibility map and the dzs locations over 85 of the dzs of the validation set are correctly classified falling in high and very high susceptibility areas also the roc curve had shown an area under curve auc value of 0 90 which demonstrates the robustness and good reliability of the landslide susceptibility model according to these results we conclude that the map produced by the artificial neural network is reliable and the methodology applied in the study produced high performance and satisfactory results which may be useful for land planning policy

reconstructing recent landslide activity in relation to rainfall in the llobregat river basin eastern pyrenees spain abstract a chronology of recent landslides in the upper basin of the llobregat river eastern pyrenees has been reconstructed from technical reports field reconnaissance and dendrogeomorphological analysis the precipitation conditions responsible for triggering and reactivating landslides have been deduced by analysis of rainfall records from two rain gauges located in the area two different rainfall patterns relate to landslide occurrence i without antecedent rainfall high intensity and short duration rains trigger mostly debris flows and shallow slides developed in colluvium and weathered rocks a rainfall threshold of around 190 mm in 24 h initiates failures whereas more than 300 mm in 24 48 h are needed to cause widespread shallow landsliding ii with antecedent rain moderate intensity precipitation of at least 40 mm in 24 h reactivates mudslides and both rotational and translational slides affecting clayey and silty clayey formations in this case several weeks and 200 mm of precipitation are needed to cause landslide reactivation dendrochronological analysis shows that landslide activity in the eastern pyrenees was relatively low between 1926 and 1959 but has since increased significantly with reactivation now occurring about every 3 years

linking hydrological infinite slope stability and land use change models through gis for assessing the impact of deforestation on slope stability in high andean watersheds in the ecuadorian andes episodic slope movements comprising shallow rotational and translational slides and rapid flows of debris and soil material are common consequently not only considerable financial costs are experienced but also major ecological and environmental problems arise in a larger geographical area sediment production by slope movement on hillslopes directly affects sediment transport and deposition in downstream rivers and dams and morphological changes in the stream channels in developing countries world wide slope movement hazards are growing increasing population pressure and economic development force more people to move to potentially hazardous areas which are less suitable for agriculture and rangelands this paper describes the methods used to determine the controlling factors of slope failure and to build upon the results of the statistical analysis a process based slope stability model which includes a dynamic soil wetness index using a simple subsurface flow model the model provides a time varying estimate of slope movement susceptibility by linking land use data with spatially varying hydrologic soil conductivity evapotranspiration soil wetness and soil strength properties the slope stability model was applied to a high andean watershed gordeleg catchment 250 ha southern ecuadorian andes and was validated by calculating the association coefficients between the slope movement susceptibility map of 2000 and the spatial pattern of active slope movements as measured in the field with gps the proposed methodology allows assessment of the effects of past and future land use change on slope stability a realistic deforestation scenario was presented past land use change includes a gradual fragmentation and clear cut of the secondary forests as observed over the last four decades 1963 2000 future land use change is simulated based on a binary logistic deforestation model whereby it was assumed that future land use change would continue at the same rate and style as over the last 37 years 1963 2000 c 2002 elsevier science b v all rights reserved

segmentation and coalescence of cenozoic carbonate platforms northwestern great bahama bank seismic profiles over the northwestern great bahama bank reveal that it is formed by the coalescence of three smaller platforms and significant lateral progradation this conclusion is contrary to previous models which assumed that the bank is the result of continuous accumulation on one huge buildup in late cretaceous to early tertiary time a north south trending depression the straits of andros separated an eastern platform andros bank from a western platform bimini bank initially the straits of andros had dimensions similar to the modem tongue of the ocean but was progressively filled from east to west in early to middle tertiary time a second depression the bimini embayment formed within bimini bank by folding it had a maximum depth of about 470 m this depression was also filled from east to west in addition prograding systems built the western margin of bimini bank more than 25 km westward into the straits of florida

the role of the sediment budget in understanding debris flow susceptibility this study proposes a sediment budget model to predict the temporal variation of debris volume stored in a debris flow prone watershed the sediment budget is dominated by shallow landslides and debris outflow the basin topography and the debris volume stored in the source area of the debris flow prone watershed help evaluating its debris flow susceptibility the susceptibility model is applied to the tungshih area of central western taiwan the importance of the debris volume in predicting debris flow susceptibility is reflected in the standardized coefficients of the proposed statistical discriminant model the high prediction rate 0 874 for the occurrence of debris flows justifies the capability of the proposed susceptibility models to predict the occurrence of debris flows this model is then used to evaluate the temporal evolution of the debris flow susceptibility index the analysis results show that the numbers of watershed which are classified as a debris flow group correspond well to storage of sediment at different time periods these numbers are 10 before the occurrence of chi chi earthquake 13 after the occurrence of chi chi earthquake 16 after the occurrence of landslides induced by typhoon mindulle typhoon m and 14 after the occurrence of debris flows induced by typhoon m it indicates that the occurrence of 7 6 chi chi earthquake had significant impact on the debris flow occurrence during subsequent typhoons copyright 2009 john wiley sons ltd

submarine landslides on the great barrier reef shelf edge and upper slope a mechanism for generating tsunamis on the north east australian coast shallow 200 m submarine landslides influence margin evolution and can produce devastating tsunamis yet little is known about these processes on mixed siliciclastic carbonate margins we have discovered seven landslides along the shelf edge and upper slope of the central great barrier reef gbr australia the largest shelf edge landslide is investigated in detail and represents a collapse of a 7 km long section of the shelf edge at 90 m water depth with coarse debris deposited up to 5 5 km away on the upper slope down to 250 m the precise timing and triggering mechanisms are uncertain but available chronologic and seismic stratigraphic evidence suggest this event occurred during the last deglacial sea level rise between 20 and 14 ka regional bathymetric data confirms that these shelf edge and upper slope slides are restricted to the central gbr between latitude 18 and 19 s suggesting a spatial relationship between the extensive burdekin paleo fluvial delta system and shallow landslide activity this study highlights an important local mechanism for the generation of tsunamis on this margin type and numerical simulations under present conditions confirm a 2 to 3 m tsunami wave could be produced locally however we consider that the risk of such slides and their resulting tsunamis to the modern coastline is negligible due to their relatively small size and the capacity of the gbr to dissipate the wave energy

application of lidar and discriminant analysis to determine landscape characteristics for different types of slope failures in heavily vegetated steep terrain horseshoe run watershed west virginia abstract a landslide inventory map was created for horseshoe run watershed west virginia using high resolution topographic data obtained from airborne lidar a total of 152 landslides were remotely mapped and classified as planar slides rotational slumps debris flows debris fans debris slides and active slopes based on morphologic characteristics interpreted from lidar derived shaded relief maps with field verification at several locations seven landscape variables were calculated for the watershed from the high resolution 0 5 m topographic data elevation slope angle slope aspect distance from roads distance from streams plan curvature and profile curvature statistical analyses were conducted to determine the mean and standard deviations for each variable and corresponding slope failure type discriminant analyses were conducted on the different types of failed slopes with a maximum 86 accuracy level to determine which landscape characteristics contribute to each type of landslide results from the discriminant analyses indicate that statistically significant differences exist between the failure classes mapped within the watershed and that slope angle slope aspect and landscape curvature are important variables influencing the type of process the results from this study have important implications for predicting where certain types of slope failures may occur based on landscape characteristics

discriminant analysis of the geomorphic characteristics and stability of landslide dams article i nfo landslides can cause the formation of dams but these dams often fail soon after lake formation thus rapidly evaluating the stability of a landslide dam is crucial for effective hazard mitigation this study utilizes discriminant analysis based on a japanese dataset consisting of 43 well documented landslide dams to determine the significant variables including log transformed peak flow or catchment area and log transformed dam height width and length in hierarchical order which affect the stability of a landslide dam the high overall prediction power 88 4 of the 43 training cases are correctly classified and the high cross validation accuracy 86 demonstrate the robustness of the proposed discriminant models phwl with variables including log transformed peak flow and log transformed dam height width and length and ahwl with variables including log transformed catchment area and log transformed dam height width and length compared to a previously proposed dbi index based graphic approach the discriminant model ahv which uses the log transformed catchment area dam height and dam volume as relevant variables shows better ability to evaluate the stability of landslide dams although these discriminant models are established using a japanese dataset only the present multivariate statistical approach can be applied for an expanded dataset without any difficulty when more completely documented worldwide landslide dam data are available

mapping bathymetry and depositional facies on great bahama bank satellite imagery and an extensive set of water depth measurements have been used to map and critically evaluate the magnitude and patterns of bathymetry across great bahama bank descriptions of previously collected sediment samples were combined with satellite imagery to map and refine the interpreted distribution of surficial carbonate sediments depositional facies data reveal that 60 of great bahama bank lies in 5 m or less of water the deep portion occurs mainly in a generally east west trending area in the southern portion of the platform the re evaluation of the facies reveals that great bahama bank is essentially a very grainy platform with muddier accumulations primarily in the lee of andros island this area of great bahama bank also experiences currents related to an excursion of the florida current onto the platform top possibly enhancing sediment mud production through the generation of whitings sediment equivalents to mudstones wackestones and mud rich packstones cover 8 5 and 14 respectively of the platform top whereas sediment equivalents to mud poor packstones grainstones and rudstones account for 20 45 and 3 of the surface area boundstones reefs were not specifically mapped in this study due to the resolution of the mapping there is a poor relationship between the occurrence of the depositional texture and water depth in that the grainier sediment types are abundant across the full range of water depths the most abrupt lateral facies changes portrayed on the facies maps are observed leeward of islands areas which also hold the highest diversity in facies type the majority of the islands on the platform align with the north west south east strike of the platform margin and these islands in turn exert control on the shape and orientation of facies belts that develop in proximity to them for this reason regions of the platform that contain principal islands host facies belts that align with the principal axis of the platform whereas for regions lacking islands the facies belts adopt an east west trend consistent with prevailing winds and currents there is a clear trend that the wide southern portion of the platform hosts the most continuous expanses of grain rich sediments

magnitude frequency characteristics and preparatory factors for spatial debris slide distribution in the northern faroe islands abstract the faroe islands in the north atlantic ocean are highly susceptible to debris avalanches and debris flows originating from debris slide activity in shallow colluvial soils to provide data for hazard and risk assessment of debris avalanches and debris flows this study aims at quantifying the magnitude and frequency of their debris slide origins as well as identifying which preparatory factors are responsible for the spatial debris slide distribution in the landscape for that purpose a debris slide inventory was generated from aerial photo interpretation api fieldwork and anecdotal sources covering a 159 km2 study area in the northern faroe islands a magnitude cumulative frequency mcf curve was derived to predict magnitude dependant debris slide frequencies while preparatory factors responsible for spatial debris slide distribution were quantified through gis supported discriminant function analysis dfa nine factors containing geological lithology dip geomorphological slope angle altitude aspect plan and profile curvature and land use infield outfield sheep density information were included in the multivariate analysis debris slides larger than 100 m2 with magnitude expressed as topographic scar area can be predicted from the power law function y 936 26x 1 277 r2 0 98 while a physical explanation is preferred for the roll over pattern of smaller slope failures the dfa is able to correctly classify app 70 of the modeled terrain units into their pre determined stable unstable groups preparatory factors responsible for the spatial debris slide distribution are aspect slope angle sheep density plan curvature and altitude while influence of the remaining factors is negligible

artificial neural networks applied to landslide susceptibility assessment abstract landslide hazard mapping is often performed through the identification and analysis of hillslope instability factors usually managed as thematic data within geographic information systems gis in heuristic approaches these factors are rated by the attribution of scores based on the assumed role played by each of them in controlling the development of a sliding process other more refined methods based on the principle that the present and the past are keys to the future have also been developed thus allowing less subjective analyses in which landslide susceptibility is assessed by statistical relationships between past landslide events and hillslope instability factors the objective of this research is to define a method with the ability to forecast landslide susceptibility through the application of artificial neural networks anns the riomaggiore catchment a subwatershed of the reno river basin located in the northern apennines italy was chosen as an ideal test site as it is representative of many of the geomorphological settings within this region in the present application two different anns used in classification problems were set up and applied one belonging to the category of multi layered perceptron mlp and the other to the probabilistic neural network pnn family the hillslope factors that have been taken into account in the analysis were the following a lithology b slope angle c profile curvature d land cover and e upslope contributing area these factors have been classified on nominal scales and their intersection allowed 3342 homogeneous domains unique condition unit ucu to be singled out which correspond to the terrain units utilized in this analysis the model vector used to train the anns is a subset of that derived from the production of unique condition units and consists of 3342 records organized in input and output variable vectors in particular the hillslope factors once classified on nominal scales as binary numbers represent the 19 input variables while the presence absence of a landslide in a given terrain unit is assumed to be the output variable the comparison between the most up to date landslide inventory of the riomaggiore catchment and the hazardous areas as predicted by the anns showed satisfactory results with a slight preference for the mlp for this reason this is an encouraging preliminary approach towards a systematic introduction of ann based statistical methods in landslide hazard assessment and mapping

assessment of shallow landslide susceptibility by means of multivariate statistical techniques several multivariate statistical analyses have been performed to identify the most influential geological and geomorphological parameters on shallow landsliding and to quantify their relative contribution a data set was first prepared including more than 30 attributes of 230 failed and unfailed slopes the performance of principal component analysis t test and one way test allowed a preliminary selection of the most significant variables which were used as input variables for the discriminant analysis the function obtained has classified successfully 88 5 per cent of the overall slope population and 95 6 per cent of the failed slopes slope gradient watershed area and land use appeared as the most powerful discriminant factors a landslide susceptibility map based on the scores of the discriminant function has been prepared for ensija range in the eastern pyrenees an index of relative landslide density shows that the results of the map are consistent copyright 2001 john wiley sons ltd language en

impact of strong easterly trade winds on carbonate petroleum exploration relationships developed from caicos platform southeastern bahamas abstract brisk persistent easterly trade wind influences define holocene patterns of carbonate sedimentation across the caicos platform southeastern bahamas resultant predictive sedimentary facies models based on trade wind influences are more widely applicable to the exploration for subsurface carbonate plays than are existing models based on the northern bahamas facies patterns which are characterized by gentle trade winds and strong platform margin related oceanic processes swells and tidal currents the caicos platform relationships may be more applicable because many ancient shallow carbonate depositional environments were within the trade wind belts and commonly within broad intracratonic seas that were little influenced by oceanic processes the grainstone dominated caicos platform exhibits reservoir potential over much of its surface in contrast to northern bahamian platforms where oceanic tidal currents or swells and gentle easterly trade winds confine higher energy environments with reservoir potential to platform margins strong easterly trade winds across caicos platform promote widespread holocene platform interior oolitic skeletal and grapestone grainstone bodies on this platform orientations of ooid sand bodies vary depending on preexisting topography water depth and bottom energy shallow subtidal ooid sand shoals orient parallel to these winds ooid sands developed along older shorelines orient parallel to the shorelines but prograde perpendicular into these winds deeper platform interior oolitic sands exist as widespread sheet like deposits these trade winds allow reefs and ooids to coexist in many settings permit isolated linear reefs to flourish on certain leeward platform margins and promote effective off bank transport of carbonate sands that create onlapping grainstone wedges these relationships are very applicable to the rock record strong trade wind influences such as seen on caicos platform better explain the occurrence of cretaceous reef and or oolitic grainstone reservoirs developed well in from platform margins fairway field in east texas black lake field in louisiana than do existing northern bahamian models depositional models based on conditions in the northern bahamian models would predict low energy facies in these platform interior settings a trade wind driven depositional model characterized by strong persistent easterlies also better explains the origin of the onlapping wedge of skeletal grainstones at poza rica oilfield in mexico the caicos platform easterly trade wind driven depositional model should generally apply to any ancient shallow carbonate environment that developed 5 22 north or south of the paleoequator whether or not a platform margin was near by future carbonate exploration or exploitation should always factor in not only geological age but also physiographic latitudinal and climatic setting at a global and local scale

susceptibility zoning of shallow landslides in fine grained soils by statistical methods abstract the paper proposes a methodology in two successive steps to zone the susceptibility to shallow landslides in fine grained soils by means of statistical methods the first step of the methodology aiming at defining calibrating and validating the statistical analysis ends with a landslide susceptibility computational map the second step of the methodology is employed to produce a susceptibility map for zoning purposes this structured methodology arises from the need to distinguish at any given scale of analysis between the spatial discretization needed to perform the statistical computations terrain computational units and terrain units useful for zoning purposes terrain zoning units the applicability of the proposed methodology is tested at two different scales 1 25 000 and 1 5000 in two areas of southern italy the test area for the larger scale being a portion of the test area used for the analysis at the smaller scale this allows for the generalization of the obtained results through the comparison for the same phenomena in the same geo environmental context of the predisposing factors at two scales of analysis in both analyses the relevant variables for the susceptibility assessment are elevation zone slope gradient slope curvature and geology in the analysis at large scale also the weathered rock thickness available only at this scale assumes a relevant role in both cases the aggregation of multiple terrain computational units tcu into a larger terrain zoning unit tzu works best when focal statistic techniques are used with a characteristic dimension of the area of influence equal to 16 tcus

slope instability in nicaragua triggered by hurricane mitch distribution of shallow mass movements the heavy rains associated with hurricane mitch triggered off a number of slope instability processes in several central american countries different instability processes have been acknowledged for the various mountainous regions of nicaragua an enormous movement of the casita volcano slopes resulted in numerous deaths and some deep movements have been reactivated on the other hand numerous shallow mass movements and debris flows have given rise to great material loss throughout a large part of nicaraguan mountains

influence of paleo trade winds on facies patterns of the cambrian shanganning carbonate platform north china abstract the shanganning carbonate platform scp of the north china craton ncc was located in the trade winds belt during the cambrian which influenced its facies development in recent years numerous drillcores have been recovered from these units but the depositional environments and facies architecture of this large 2 0 105 km2 carbonate platform system have not yet been reported in detail in this study we integrate sedimentological and magnetic fabric data collected from outcrops and drillcores in order to document variation in microfacies and facies associations within the scp to infer paleowind directions and constrain the paleogeographic location of the scp and to evaluate eolian controls on platform development this analysis documented numerous carbonate microfacies belonging to six fabric types mudstone wackestone packstone grainstone framestone and dolostone along with rarer siliciclastic sediments these microfacies belong to facies associations representing tidal flat open platform platform margin slope and deep basinal depositional environments anisotropy of magnetic susceptibility ams measurements yielded mean paleocurrent directions for the early middle and late cambrian of 114 63 and 83 30 from paleo north respectively that were relatively consistent for 12 out of 13 platform margin sites all vectors being corrected for a post cambrian 150 clockwise rotation of the ncc these wind orientations are consistent with the scp shifting from south of the paleo equator in the early cambrian to north of it by the middle cambrian paleo trade winds influenced facies patterns across the platform producing a distinct windward leeward zonation the windward margin is characterized by well sorted oolitic grainstone as well as favositids coral and dasycladacean algal sponge framestone and the leeward margin by poorly sorted oolitic wackestone grainstone and fine bioclastic sediments the present study is innovative in 1 integrating microfacies and ams analyses in order to establish paleowind patterns and influences on an ancient carbonate platform 2 documenting windward leeward variation in quantifiable sediment properties across the scp and 3 constraining the paleo hemispheric location of the ncc during the cambrian

discovery of ring faults associated with salt withdrawal basins early cretaceous age in the east texas basin abstract the jurassic louann salt in the east texas basin has played a dominant role in influencing the structural and depositional history of the basin particularly during the jurassic and cretaceous periods salt tectonics is closely associated with sandstone distribution depositional facies and reef growth and consequently with petroleum traps in the basin salt withdrawal basins developed during the early cretaceous in response to salt movement and dissolution processes are characterized by the presence of an expanded section of lower cretaceous marine and deltaic sedimentary rocks recognition of fault sets associated with the evolution of these salt withdrawal basins has gone undetected until the recent coherence cubetm processing of a non proprietary 3 d seismic survey conducted by schlumberger in the la rue dome fairway field area henderson county texas images from coherence cube processing aptly exhibit extraordinary sets of concentric ring faults that comprise the periphery of two salt withdrawal basins the fairway oil field is located at the junction of these two sets of ring faults the structural style of these high angle ring faults creates a multitude of possible fault traps in a previously unattractive structural setting early cretaceous age of the ring faults establishes that these faults are a significant element in evaluating petroleum migration patterns and traps in the basin the discovery of early cretaceous ring faults in the east texas basin by coherence cube processing brings new perspectives to development and exploration drilling in this mature petroleum province

hurricane deposits on carbonate platforms a case study of hurricane irma deposits on little ambergris cay turks and caicos islands the study of modern hurricane deposits is useful in both identifying ancient hurricane deposits in the rock record and predicting patterns of deposition and erosion produced by future storm events hurricane deposits on carbonate platforms have been studied less frequently than have been those along continental coasts here we present observations of the characteristics of deposition and scour caused by hurricane irma on little ambergris cay a small uninhabited island located near the southeastern edge of the caicos platform in the turks and caicos islands hurricane irma passed directly over little ambergris cay on 7 september 2017 as a category 5 hurricane we described and sampled multiple types of hurricane deposits and determined that the washover fans were the best sedimentological records for hurricane conditions as they were subject to very little reworking over time we compared different model predictions of storm tide and wave height with eyewitness reports and distributions of scour examining the washover fans allowed for the construction of a conceptual model for hurricane deposits formed in a high energy storm event on a carbonate platform characteristics of the washover fans were their small size the lack of sedimentary structures and very well sorted sediment the size and distribution of carbonate boulders eroded and transported by the storm are consistent with depth averaged flow velocities in the range of 1 5 5 3 m s the strength of the storm and the low lying topography distinct features of a carbonate platform setting contributed to high levels of sediment bypass and high flow velocities resulting in small unstructured deposits

comparison of logistic regression and random forests techniques for shallow landslide susceptibility assessment in giampilieri ne sicily italy abstract the aim of this work is to define reliable susceptibility models for shallow landslides using logistic regression and random forests multivariate statistical techniques the study area located in north east sicily was hit on october 1st 2009 by a severe rainstorm 225 mm of cumulative rainfall in 7 h which caused flash floods and more than 1000 landslides several small villages such as giampilieri were hit with 31 fatalities 6 missing persons and damage to buildings and transportation infrastructures landslides mainly types such as earth and debris translational slides evolving into debris flows were triggered on steep slopes and involved colluvium and regolith materials which cover the underlying metamorphic bedrock the work has been carried out with the following steps i realization of a detailed event landslide inventory map through field surveys coupled with observation of high resolution aerial colour orthophoto ii identification of landslide source areas iii data preparation of landslide controlling factors and descriptive statistics based on a bivariate method frequency ratio to get an initial overview on existing relationships between causative factors and shallow landslide source areas iv choice of criteria for the selection and sizing of the mapping unit v implementation of 5 multivariate statistical susceptibility models based on logistic regression and random forests techniques and focused on landslide source areas vi evaluation of the influence of sample size and type of sampling on results and performance of the models vii evaluation of the predictive capabilities of the models using roc curve auc and contingency tables viii comparison of model results and obtained susceptibility maps and ix analysis of temporal variation of landslide susceptibility related to input parameter changes models based on logistic regression and random forests have demonstrated excellent predictive capabilities land use and wildfire variables were found to have a strong control on the occurrence of very rapid shallow landslides

application of analytic hierarchy process model for landslide susceptibility mapping in the gangu county gansu province china the purpose of the present study was to produce a landslide susceptibility map using analytic hierarchy process ahp model based on gis for gangu county china for this purpose a detailed landslide inventory map was prepared and eight landside conditioning factors were considered these factors were slope angle plan curvature altitude distance from faults distance from rivers distance from roads rainfall and lithology the landslide inventory map was prepared by literatures aerial photographs and field surveys and a total of 328 landslides were identified in the study area all landslides were applied for establishing the model and validating the model the arcgis package was used to evaluate landslide susceptibility and analyze landslide conditioning factors as a result a landslide susceptibility map was generated using analytic hierarchy process model based on arcgis 10 0 and divided into five susceptibility classes very low low moderate high and very high finally in order to validate the accuracy of the landslide susceptibility map produced from ahp model both physical and statistical methods were applied the success rate curve results showed that the susceptibility map using ahp model has a success rate of 73 74 therefore the landslide susceptibility map will be helpful for landside hazard assessment and land use planning in the study area

reflux dolomitization a holocene example beneath a coastal salina west caicos island turks and caicos islands abstract holocene reflux dolomitization occurred beneath the company point evaporitic coastal salina on west caicos island less than 1 km in from the edge of caicos platform in the southeastern bahamas poorly ordered calcian rich protodolomites replaced coralgal grainstones shed into the salina as storm washover deposits and also cemented them finer grained carbonate sands were replaced by fine crystalline dolomites but coarser grained skeletal fragments including halimeda sp dissolved out to create late holocene precompactional secondary moldic porosity precipitation of overlying evaporitic deposits principally gypsum generated magnesium rich brines below these evaporites the downward increase in the degree of replacement dolomitization toward the impermeable calcrete that caps pleistocene grainstones at the base of the holocene sequence strongly implies reflux dolomitization company point dolomitization less than 1 km in from the western edge of caicos platform demonstrated that this process is not limited to platform or ramp interior settings well removed from the open ocean a semi arid climate combined with depositional ridge topography and periodic storm surge and groundwater recharge allowed this coastal salina to initiate and evolve as these beach ridge and evaporitic deposits continue to prograde as they are doing on the eastern side of west caicos island then one can expect associated evaporitic deposits to have the potential not only to serve as an updip sealing facies but to generate mg rich fluids to create precompactional porous dolostones with sheet like reservoir quality

permian wolfcamp limestone reservoirs powell ranch field eastern midland basin deep water carbonate channel reservoirs form important oil reservoirs along the toe of the eastern shelf of the permian basin in west texas in northwestern glasscock county these wolfcamp reservoirs are leonardian early permian in age and define high energy channels incised into surrounding carbonate detritus and basinal shale porous grain flow material filling these channels along with encasing detritus was derived from the shallow shelf located six miles to the east reservoirs are in packstone and grainstone facies and have significant interparticle and moldic porosity relevant exploration began in the 1960s but expanded slowly thereafter due to lack of success caused by complex patterns of channel occurrence results of a three dimensional 3 d seismic survey conducted in 1990 have greatly enhanced the identification and mapping of productive channels in the powell ranch field complex wells in this complex are capable of flowing 400 1200 bbl of oil per day and have reserves ranging from 0 2 to 1 3 mbo the new 3 d data have improved the relevant geologic model and dramatically increased rates of drilling success application of such data to this setting offers a potential model for other parts of the permian basin

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

random forests and evidential belief function based landslide susceptibility assessment in western mazandaran province iran in many parts of the world landslide susceptibility remains inadequately mapped due to the lack of both data and suitable methods for widespread implementation iran is one of those countries with extensive landslide problems with nearly 4900 large landslides occurring between 1993 and 2007 at the same time landslide susceptibility has not been assessed for the country random forest rf has recently been shown to be a suitable tool for such mapping in this study we further coupled the rf method with an evidential belief function ebf approach and tested the suitability for landslide susceptibility mapping for variable terrain and data conditions in the west of mazandaran province northern iran locations of earlier landslides were identified by interpreting aerial photographs and through extensive field surveys eleven conditioning factors were used in the rf model the spatial relationship between landslide occurrence and conditioning factors was then assessed using the data driven ebf model and ebf values paired to each map finally the ebf maps were used for running the rf model finally the efficiency of the rf ebf model was tested using the area under the curve to measure the success and prediction rates of the incorporated data this resulted in a success rate of 85 2 and a prediction rate of 81 8 the most important conditioning factors identified were lithology altitude distance from roads and land use respectively based on the overall assessment the combined rf and ebf approach was found to be objective and an applicable estimator that improves the predictive accuracy and controls for overfitting and thus useful for landslide susceptibility mapping at regional scales

analysis of environmental controls on tsunami deposit texture abstract tsunamis transport large amounts of sediment and can leave recognisable signatures in the landscape the form and composition of onshore tsunami deposits are a function of wave dynamics sediment availability and characteristics of the local environment the latter of which also partially controls preservation of the deposit this research reviews these relationships in a global context and assesses the connection between tsunami deposit particle size and four controlling parameters climate temperature and rainfall density of tsunami sediments degree of coastal protection and distance between tsunami source and sediment deposition an international dataset of tsunami deposit locations and texture was compiled from published literature and existing databases values for environmental variables were calculated for each location from global datasets of temperature rainfall coastline shape and tsunami source locations spearman s rank order correlation principal component analysis pca and hierarchical cluster analysis ca were used to analyse relationships between these variables pca results show an inverse relationship between particle size and sediment density climate variables and distance from source ca results support this suggesting a cluster structure controlled primarily by particle size and secondly by climate and sediment density these relationships can be explained by the influence of the environment on antecedent morphology and the composition of sediments available for tsunami transport

landslide susceptibility mapping using frequency ratio analytic hierarchy process logistic regression and artificial neural network methods at the inje area korea every year the republic of korea experiences numerous landslides resulting in property damage and casualties this study compared the abilities of frequency ratio fr analytic hierarchy process ahp logistic regression lr and artificial neural network ann models to produce landslide susceptibility index lsi maps for use in predicting possible landslide occurrence and limiting damage the areas under the relative operating characteristic roc curves for the fr ahp lr and ann lsi maps were 0 794 0 789 0 794 and 0 806 respectively thus the lsi maps developed by all the models had similar accuracy a cross tabulation analysis of landslide occurrence against non occurrence areas showed generally similar overall accuracies of 65 27 64 35 65 51 and 68 47 for the fr ahp lr and ann models respectively a correlation analysis between the models demonstrated that the lr and ann models had the highest correlation 0 829 whereas the fr and ahp models had the lowest correlation 0 619

comparing models of debris flow susceptibility in the alpine environment abstract debris flows are widespread in val di fassa trento province eastern italian alps where they constitute one of the most dangerous gravity induced surface processes from a large set of environmental characteristics and a detailed inventory of debris flows we developed five models to predict location of debris flow source areas the models differ in approach statistical vs physically based and type of terrain unit of reference slope unit vs grid cell in the statistical models a mix of several environmental factors classified areas with different debris flow susceptibility however the factors that exert a strong discriminant power reduce to conditions of high slope gradient pasture or no vegetation cover availability of detrital material and active erosional processes since slope and land use are also used in the physically based approach all model results are largely controlled by the same leading variables overlaying susceptibility maps produced by the different methods statistical vs physically based for the same terrain unit of reference grid cell reveals a large difference nearly 25 spatial mismatch the spatial discrepancy exceeds 30 for susceptibility maps generated by the same method discriminant analysis but different terrain units slope unit vs grid cell the size of the terrain unit also led to different susceptibility maps almost 20 spatial mismatch maps based on different statistical tools discriminant analysis vs logistic regression differed least less than 10 hence method and terrain unit proved to be equally important in mapping susceptibility model performance was evaluated from the percentages of terrain units that each model correctly classifies the number of debris flow falling within the area classified as unstable by each model and through the metric of roc curves although all techniques implemented yielded results essentially comparable the discriminant model based on the partition of the study area into small slope units may constitute the most suitable approach to regional debris flow assessment in the alpine environment

landslide zoning over large areas from a sample inventory by means of scale dependent terrain units abstract a procedure is proposed to produce landslide distribution zoning maps to be considered preparatory to susceptibility hazard and risk zoning maps based on 1 the results from a statistical multivariate analysis of a landslide inventory which must be available for only a portion of the territory to be zoned and 2 the use of appropriately defined terrain mapping units the units are divided into terrain computational units tcus and terrain zoning units tzus whose size is related to the scale of zoning the procedure comprises three phases calibration validation and prediction the purpose of the prediction phase is the application of a calibrated and validated statistical model in a territory previously recognized as viable on the basis of a priori applicability maps for which no information is available regarding the distribution of landslides or where the information provided by the landslides inventory is unreliable or heterogeneous the proposed procedure is applied to two case studies in southern italy for the analysis and zoning of slow moving landslides at 1 25 000 and 1 100 000 scales respectively the first case study illustrates the applicability of the procedure the aim of the second case study is to address the part of the procedure related to the evaluation of the computational maps at the end of the calibration and validation phases

impacts of post glacial rebound on landslide spatial distribution at a regional scale in northern iceland skagafjorður in de glaciated areas para glaciation i e the conditioning of landscapes by prior glaciation has often been considered a major predisposing factor in landslide occurrence its consequences have been particularly well identified at a fine scale especially on bedrock jointing hitherto the relative impacts of para glaciation on hillslope dynamics at a regional scale had nevertheless not been quantified statistically we examine skagafjor ur area northern iceland where landslides are widespread at least 108 were mapped in an area of c 3000km2 we compare the role of para glaciation debuttressing influence of post glacial rebound with that of classic factors topography lithology etc in landslide occurrence and location using a spatial analysis based on a chi square test on the one hand the results highlight that landslides are over represented in areas where post glacial rebound was at its maximum with a stronger concentration of landslides in the northern part of the fjord on the other hand the distribution of landslides did not show any clear relationship with the pattern of glacial debuttressing tschuprow coefficient highlights that the influence of post glacial rebound on landslide location is higher than the combined influence of slope gradient curvature or geological structure this result is supported by our initial evidence for the timing of landslides in the area most landslides occurred during the first half of the holocene and a period of hillslope instability was initiated when the post glacial uplift was at its maximum finally the mechanisms that link post glacial rebound and landsliding as well as the geomorphic impacts of landslides are discussed

gis based frequency ratio and index of entropy models to landslide susceptibility mapping daguan china the main goal of this study is to produce landslide susceptibility maps by frequency ratio fr and index of entropy ioe models based on geographic information system gis for the daguan county of yunnan province china at first landslide locations were identified by earlier reports and aerial photographs as well as by carrying out field surveys and a total of 194 landside locations were constructed from various sources then the landslide inventory map was randomly split into a training dataset 70 136 landslide locations for training the fr and ioe models and the remaining 30 58 landslides locations were used for validation purposes fifteen landslide conditioning factors were constructed in gis the susceptibility maps produced using fr and ioe models were divided into five different susceptibility classes such as very low low moderate high and very high finally the validation of landslide susceptibility maps was carried out based on training dataset and the validation data using the area under the curve auc method the success rate curve showed that the area under the curve for fr and ioe models were 0 8191 and 0 8109 accuracy respectively similarly the validation result showed that the prediction accuracy of the two models was 81 75 for fr model and 81 44 for ioe model respectively the maps produced by both models exhibits better satisfactory properties the landslide susceptibility maps may be useful for planning purposes for environmental protection and natural hazard mitigation studies in the near future

granite cored domes and gold mineralisation architectural and geodynamic controls around the archaean scotia kanowna dome kalgoorlie terrane western australia abstract granite cored domes are associated with many of the larger gold deposits of the archaean eastern yilgarn craton of western australia the scotia kanowna dome is eroded to sufficiently deep levels to provide insights into the role granite cored domes play in controlling fluid flow and gold deposition at the centre of the scotia kanowna dome is a granite batholith which is surrounded by outward dipping greenstone belts and associated shear zones this upper crustal dome sits above mid crustal domes providing a series of stacked geometries favourable to focussed fluid flow a number of small to medium sized gold deposits occur on the limbs and the centre of the dome and the world class kanowna belle gold mine occurs on the nose of the dome at least three separate gold mineralising events are defined each of regional significance which can be correlated with other well known gold deposits of the eastern yilgarn craton the palaeostress across this region was dominated by both maximum contractional and extensional vectors oriented perpendicular to the north northwest trending grain the resultant strain is seen in the architecture of the scotia kanowna dome with its margins and associated shear zones controlling the distribution of stratigraphy which is relatively linear and parallel to the margin throughout most of the tectonic history the flanking shear zones were high strain domains that recorded multiple stages of contraction with thrust and mostly sinistral strike slip shear kinematics in contrast the dome nose region was a relatively low strain domain as it was located in the strain shadow of the regional contractional events for example the early extensional record has been preserved at the nose with late stage basins formed in the hangingwall to the extensional faults adding to the stratigraphic complexity of the local region these late basins also may have contributed to the fluid budget in contrast along the flanks of the domes there is no record of these late basins or the extensional faults that controlled their deposition the architecture of the dome played an important role in controlling mineralisation during a significant deviation in the maximum contractional stress vector to an east southeast west southwest orientation at this time basins in the nose region underwent inversion with thrusting to the north and northwest shortening was accommodated along the dome flanks by sinistral strike slip shearing which was relatively free to move due to the mostly linear stratigraphy combined with limited anisotropy and perturbations along the flank however the stratigraphic and geometrical complexity around the dome nose resulted in localised maximum dilation and gold deposition at this time the dome nose area was also a favoured locus for gold enriched dominantly mafic type magmas which are seen as the extensive porphyry swarms in the region these felsic intermediate rocks also may have contributed to the complex fluid budget and are considered as indicators of particular fertility for gold they may have been the primary source for much of the metal endowment the architecture of granite cored domes has played a critical role in focussing magma as well as mineralising fluids into regions of maximum dilation they did this by virtue of their inherent competence and by influencing the position and geometry of shear zones fluid pathways and hence distribution of stratigraphy depositional sites across the region the scotia kanowna dome is a good example of this effect and inferences can be made in favour of similar controls by concealed domes such as beneath kalgoorlie

quantitative landslide hazard assessment along a transportation corridor in southern india abstract a quantitative model for landslide hazard assessment on natural slopes is presented for a transportation corridor of the nilgiri hills in southern india the data required for the hazard assessment were mostly obtained from historical records for the hazard modeling a landslide inventory map was prepared from technical reports and maintenance records for a road and a railroad available for a 21 year period from 1987 to 2007 most landslides are shallow translational debris slides and debris flow slides triggered by rainfall on natural slopes landslides occurred as first time failures a logistic regression model was used to determine the spatial probability of landslides for each pixel by taking the source area of the existing landslides as dependent and slope angle aspect regolith thickness and land use as independent variables the temporal probability of landslides was estimated indirectly using the exceedance probability of the rainfall threshold required to trigger landslides for the first time on natural slopes the probability of landslide size was estimated as frequency percentage of landslide volume a proxy for landslide magnitude and the percentage values were then expressed as probability by assuming independence among the three probabilities a quantitative estimate of a landslide hazard was obtained as the joint probability of landslide volume of landslide occurrence in an established time period and of spatial probability of a landslide initiation the models were validated using the rainfall and landslide events that occurred during 2008 and 2009 total 12 specific landslide hazard maps were generated considering six time periods 1 3 5 15 25 and 50 years and two landslide volumes volume exceeding 1000 m 3 and 10 000 m 3

accumulation of bank top sediment on the western slope of great bahama bank rapid progradation of a carbonate megabank high resolution seismic profiles and submersible observations along the leeward slope of western great bahama bank show large scale export of bank top sediment and rapid progradation of the slope during the holocene a wedge shaped sequence up to 90 m thick is present along most of the slope and consists of predominantly aragonite mud derived from the bank since flooding of the platform 6 8 ka total sediment volume of the slope sequence is 40 80 that of holocene sediment currently retained on the bank maximum rates of vertical accumulation and lateral progradation are 11 15 m ka and 80 110 m ka respectively 10 to 100 times greater than previously known for periplatform muds slope deposition of exported mud during sea level highs appears to have been a major mechanism for the westward progradation of great bahama bank throughout the quaternary this may provide a critical modern analogue for ancient progradational margins

combining spatial data in landslide reactivation susceptibility mapping a likelihood ratio based approach in w belgium a key issue in landslide susceptibility mapping concerns the relevance of the spatial data combination used in the prediction various combinations of high resolution predictor variables and possibilities of selecting them from a larger dataset are analysed the scarp reactivation of several landslides in a hilly region of w belgium is investigated at the pixel scale the susceptibility modelling uses the reactivated scarp segments as the dependent variable and 13 factors at a 2 m resolution related to topography hydrology land use and lithology as potential independent variables the modelling uses a likelihood ratio approach based on the comparison for each independent variable between two empirical distribution functions edfs respectively for the reactivated and non reactivated areas it uses these edfs as favourability values to build membership values and combine them with a fuzzy gamma operator five different data combinations are tested and compared by analysing the prediction rate curves obtained by cross validation the geomorphological value of the resulting susceptibility maps is also discussed this research shows relevant results for predicting the susceptibility to scarp reactivation we highlight the need for testing several data combinations and underline that combining quantitative criteria with expert opinion is an asset for reliable predictions

probabilistic landslide hazard assessment at the basin scale abstract we propose a probabilistic model to determine landslide hazard at the basin scale the model predicts where landslides will occur how frequently they will occur and how large they will be we test the model in the staffora river basin in the northern apennines italy for the study area we prepare a multi temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1955 and 1999 we partition the basin into 2243 geo morpho hydrological units and obtain the probability of spatial occurrence of landslides by discriminant analysis of thematic variables including morphological lithological structural and land use for each mapping unit we obtain the landslide recurrence by dividing the total number of landslide events inventoried in the unit by the time span of the investigated period assuming that landslide recurrence will remain the same in the future and adopting a poisson probability model we determine the exceedance probability of having one or more landslides in each mapping unit for different periods we obtain the probability of landslide size by analysing the frequency area statistics of landslides obtained from the multi temporal inventory map assuming independence we obtain a quantitative estimate of landslide hazard for each mapping unit as the joint probability of landslide size of landslide temporal occurrence and of landslide spatial occurrence

lithology controls the regional distribution and morphological diversity of montane mediterranean badlands in the upper llobregat basin eastern pyrenees abstract badlands are pervasive in a wide range of environmental conditions across the mediterranean region including arid semiarid and humid environments on montane cold subhumid and humid mediterranean landscapes harsh thermal conditions on north facing hillslopes favour intense bedrock weathering by freezing and impose serious constraints on plant colonization the above are the customary arguments to explain the high abundance of montane badlands on north exposed shady aspects we studied the distribution and morphological diversity of badlands in the upper llobregat basin catalan pyrenees ne spain using remote sensing information high resolution orthophotos and complementary landsat 8 imagery digital elevation data and regional information on lithology badlands extend over about 200 ha in the upper llobregat basin and occur on two different parent materials swelling smectite rich continental garumnian lutites of late cretaceous age and nonswelling illitic marine eocene marls vegetation assessed by remote sensed vegetation greenness is less developed on north facing badland slopes however badland slope aspect distribution varies considerably with lithology while badlands on eocene marls show preferential distribution on north facing shady slopes badland occurrence on garumnian lutites does not reveal clear slope aspect anisotropy patterns lithology also affects slope gradient with badlands on eocene marls showing rougher topography 30 40 average slope angle than on garumnian lutites 20 30 badland morphological differences induced by lithology are discussed in terms of the greater weathering susceptibility and slope instability of the swelling smectite rich garumnian lutites than of the nonswelling eocene marls elevation which broadly controls annual precipitation and winter air temperature within the region shows no clear influence on badland distribution overall our results reveal lithology as the main factor controlling badland distribution and morphological diversity under the montane mediterranean conditions of the upper llobregat basin

beach and shoreface ooid deposition on shallow interior banks turks and caicos islands british west indies abstract modern ooids are forming and accumulating as beach dune complexes which face into and prograde across the very shallow broad low energy caicos bank this contrasts with other modern oolite occurrences that are located at shelf margins or at the heads of steep ramps facing deeper water where tidal energy plays an important role in ooid generation ooid quality and distribution coupled with radiocarbon dating indicates that the caicos ooids are forming in the beach and shoreface environment in response to wave and current agitation generated by prevailing southeasterly trade winds the caicos model is a useful analog for many ancient sheetlike oolite accumulations deposited on broad epeiric shelves or gently sloping ramps

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

comparison of satellite and air photo based landslide susceptibility maps landslide susceptibility maps can be prepared in a variety of ways many geoscientists favour the use of an overlay model approach in which several map layers are combined by some arithmetic rules to determine the potential for sliding in an area or region the resulting susceptibility maps although based on a subjective weighting of relevant factors can often be of high accuracy and utility in order to obtain the relevant input data for this type of analysis remotely sensed data are often used to date susceptibility mapping just as the mapping of historic and individual landslides has tended to require higher resolution imagery this has somewhat limited the application of landslide susceptibility mapping while high resolution air photo or satellite imagery is superior to lower resolution imagery for the purpose of mapping of historic and individual landslides such higher levels of resolution may not be required for the development of landslide susceptibility maps in order to determine if medium resolution satellite imagery such as spot or aster could provide the needed data for landslide susceptibility mapping a comparison was undertaken of landslide susceptibility model output resulting from the use of stereo napp aerial photography versus the use of data obtained from stereo spot imagery the test area selected for this study consisted of two watersheds pena canyon and big rock canyon situated west of santa monica california usa along the pacific coast highway both watersheds have a long and well documented history of landslide activity and sufficient geologic variability and complexity to provide a good test site the specific overlay model used in this evaluation required input data consistent with the needs of many other models of this type the model output derived from the two different data sources and presented here in the form of susceptibility maps were virtually identical statistical and difference analysis confirmed that both methods of obtaining input data provide similar results and successfully identified landslide prone areas these results suggest that satellite imagery in this instance spot images could potentially be used in lieu of conventional air photos to evaluate landslide susceptibility in many situations especially in the case of remote locations and or developing countries this capability should result in substantial savings in terms of time financial resources and overall viability

slope instability analysis in south patagonia applying multivariate and bivariate techniques on landsat images during 2001 2015 period abstract we present results of the estimation of surface changes associated with slope instability processes on the upsala channel by remote sensing and statistic techniques hillslopes involving lateral moraines of upsala channel at the argentino lake have become potentially unstable due to the retreat of upsala glacier during the last century the glaciation and deglaciation processes modify the tensions on the slope stability and may generate landslide processes a landslide movement destroyed the western edge of the upsala channel in february 2013 in addition the region represents a great tourist attraction usually ships navigate through the upsala channel seeing impressive landscapes especially the upsala glacier stand out due to this risky situation the necessity of increasing the knowledge in the area has arisen but has not been addressed yet therefore the main goal of the present study is to investigate the multivariate statistical techniques by the principal component analysis pca and discriminative analysis da in four testing areas tasn besides we include pearson s correlation coefficient pcc and normal distribution nd to determine whether the testing areas suffered slope movements or were temporally stable the study is based on landsat optical satellite images acquired during the period from october 2001 to april 2015 the results show that tas1 2 4 are less stable whereas tas5 is a more stable area as compared to another tas the pc1 and pc2 principal components explained the total variability of the 76 data the total apparent error of da reached 2 2 points the pcc achieved a positive trend during the years when movement on the slope surface was not observed while during the periods when slope instability was observed the correlation showed a negative trend the tasn that had shown a different behavior presented contrasted gaussian bells they are more flattened in those years with instability events

assessment of susceptibility to earth flow landslide using logistic regression and multivariate adaptive regression splines a case of the belice river basin western sicily italy abstract in this paper terrain susceptibility to earth flow occurrence was evaluated by using geographic information systems gis and two statistical methods logistic regression lr and multivariate adaptive regression splines mars lr has been already demonstrated to provide reliable predictions of earth flow occurrence whereas mars as far as we know has never been used to generate earth flow susceptibility models the experiment was carried out in a basin of western sicily italy which extends for 51 km 2 and is severely affected by earth flows in total we mapped 1376 earth flows covering an area of 4 59 km 2 to explore the effect of pre failure topography on earth flow spatial distribution we performed a reconstruction of topography before the landslide occurrence this was achieved by preparing a digital terrain model dtm where altitude of areas hosting landslides was interpolated from the adjacent undisturbed land surface by using the algorithm topo to raster this dtm was exploited to extract 15 morphological and hydrological variables that in addition to outcropping lithology were employed as explanatory variables of earth flow spatial distribution the predictive skill of the earth flow susceptibility models and the robustness of the procedure were tested by preparing five datasets each including a different subset of landslides and stable areas the accuracy of the predictive models was evaluated by drawing receiver operating characteristic roc curves and by calculating the area under the roc curve auc the results demonstrate that the overall accuracy of lr and mars earth flow susceptibility models is from excellent to outstanding however auc values of the validation datasets attest to a higher predictive power of mars models auc between 0 881 and 0 912 with respect to lr models auc between 0 823 and 0 870 the adopted procedure proved to be resistant to overfitting and stable when changes of the learning and validation samples are performed in conclusion the highly acceptable predictive skill of the statistical models confirms the reliability of the procedure adopted to reconstruct the pre failure topographic conditions such a method solves the conceptual problem arising when post failure elevation data are the only source of topographic information available to model landslide susceptibility furthermore with respect to other solutions proposed in the past which identify as unstable the conditions of landslide surroundings our approach allows for more accurate measurement of those variables e g curvature convergence index topographic position index that depend on the relative position of a cell with respect to its nearby pixels

landslide susceptibility assessment using logistic regression and its comparison with a rock mass classification system along a road section in the northern himalayas india landslide studies are commonly guided by ground knowledge and field measurements of rock strength and slope failure criteria with increasing sophistication of gis based statistical methods however landslide susceptibility studies benefit from the integration of data collected from various sources and methods at different scales this study presents a logistic regression method for landslide susceptibility mapping and verifies the result by comparing it with the geotechnical based slope stability probability classification sspc methodology the study was carried out in a landslide prone national highway road section in the northern himalayas india logistic regression model performance was assessed by the receiver operator characteristics roc curve showing an area under the curve equal to 0 83 field validation of the sspc results showed a correspondence of 72 between the high and very high susceptibility classes with present landslide occurrences a spatial comparison of the two susceptibility maps revealed the significance of the geotechnical based sspc method as 90 of the area classified as high and very high susceptible zones by the logistic regression method corresponds to the high and very high class in the sspc method on the other hand only 34 of the area classified as high and very high by the sspc method falls in the high and very high classes of the logistic regression method the underestimation by the logistic regression method can be attributed to the generalisation made by the statistical methods so that a number of slopes existing in critical equilibrium condition might not be classified as high or very high susceptible zones

identification of topographic settings conducive to landsliding from dem in nelson county virginia u s a the steep terrains in the blue ridge mountains of virginia are potentially vulnerable to landsliding hundreds of slope failures were initiated by a severe storm in 1969 in nelson county virginia the outlines of 87 landslide scars were delineated on aerial photographs within a 28 8 km2 area a digital elevation model dem of the same area was constructed from which three topographic variables slope orientation gradient and form were derived overlay analyses of the landslide data and the topographic data followed by chi square tests revealed that the topographic variables studied are statistically significant to the spatial distribution of the sites disturbed by landslide paths while the landsliding potential is low at very low and high elevations it is found to be high in the median range of elevation west northwest north and northeast facing slopes are consistently more vulnerable to landsliding than their east southeast south and southwest facing counterparts terrains with a gentle gradient are stable but the potential for landslides to develop increases greatly as the terrains become steeper the slopes with a concave cross section are more susceptible to landsliding than those having other shapes furthermore the landsliding potential does not vary significantly with slope forms in the profile direction it is concluded that the introduction of a dem to this study has provided renewed insight into topographic settings conducive to landsliding which could not have been achieved otherwise

comments on anatomy of a late quaternary carbonate island constraints on timing and magnitude of sea level fluctuations west caicos turks and caicos islands bwi by kerans et al quat sci rev 205 2019 193 223 abstract we comment on interpretations of the evolution of late pleistocene geology on west caicos island caicos platform b w i by kerans et al 2019 which omits our documentation of the interrelationship of carbonate facies in outcrop and in boreholes dravis and wanless 2017 we further disagree with their geochronological dating assumptions results that are the basis for interpreting late quaternary sea level fluctuations

assessment of debris flow hazards using a bayesian network abstract comprehensive assessment of debris flow hazard risk is challenging due to the complexity and uncertainties of various related factors a reasonable and reliable assessment should be based on sufficient data and realistic approaches this study presents a novel approach for assessing debris flow hazard risk using bn bayesian network and domain knowledge based on the records of debris flow hazards and geomorphological environmental data for the chinese mainland approaches based on bn svm support vector machine and ann artificial neural network were compared bn provided the highest values of hazard detection probability precision and auc area under the receiver operating characteristic curve the bn model is useful for mapping and assessing debris flow hazard risk on a national scale

tectonic and paleogeographic controls on development of the early middle ordovician shanganning carbonate platform ordos basin north china lower middle ordovician platform carbonates are important oil and gas reservoir rocks in the ordos basin of the north china craton ncc in recent years numerous cores have been recovered from these units but the depositional environments and facies architecture of this large carbonate platform system have not yet been reported in detail this study integrates sedimentological and magnetic fabric data collected from outcrops and cores to document variation in microfacies and facies associations within the shanganning carbonate platform scp infer paleowind directions and the paleogeographic location of the scp and evaluate tectonic and paleogeographic controls on platform development this analysis documented 25 microfacies belonging to 7 microfacies fabric and sediment types carbonate mudstone wackestone packstone grainstone evaporite bindstone framestone siliciclastics and dolostone microfacies can be grouped into facies associations that represent tidal flat open platform restricted platform evaporite platform platform margin slope and deep basinal depositional environments these environments are mainly distributed zonally around the l shaped qingyang paleo uplift on the western and southern margins of the scp anisotropy of magnetic susceptibility measurements at five platform margin locales yielded paleocurrent directions of all approximately 318 348 51 81 42 72 80 110 and 54 84 from paleo north after correction for a 120 150 clockwise rotation of the ncc since the ordovician the depositional architecture of the scp depended on a combination of tectonic and paleogeographic wind influences local tectonic movements controlled the spatial distribution of facies associations around the qingyang paleo uplift which was characterized by open restricted and evaporite platform facies in the platform interior and mainly slope and basinal facies on the outer platform margin to the west and south of the qingyang paleo uplift vertical tectonic movements resulted in cyclic submergence and emergence of the platform over its approximately 20 m y long formation history paleo trade winds influenced aspects of facies zonation across the platform including growth of metazoan reefs on the windward platform margin and formation of oolitic grainstone and microbial reefs on the leeward platform margin the facies model for the scp developed in this study should provide a useful reference framework for future carbonate oil and gas exploration in lower middle ordovician units of the ordos basin furthermore this study makes innovative use of magnetic anisotropy data in combination with standard petrographic core and field data to discern facies patterns and controls on a paleo carbonate platform which is an integrated methodology that may serve as a model for future studies of other carbonate platforms

thrust sequences in the eastern spanish pyrenees detailed mapping of the south pyrenean zone in the eastern spanish pyrenees shows that a great number of alpine thrusts affect the basement and the cover the geometry of the thrust structures and their propagation sequence can be interpreted from balanced sections the folding dies out downwards from the higher thrust sheets to the lower ones and demonstrates a piggy back thrusting sequence these thrusts form a duplex the sole thrust of this duplex is the vallfogona thrust the roof thrust is rooted somewhere within the axial zone the thrusts climb southwards from the axial zone basement up into tertiary cover sediments these thrusts have been folded so that they now dip to the south and form the southern side of the axial zone antiformal stack locally smaller antiformal stacks developed and produced strong folds in the higher thrust sheets the south pyrenean zone studied is equivalent to the gavarnie nappe and the connection between them below the detached south pyrenean central unit may be the nogueres zone

landslide susceptibility mapping at central zab basin iran a comparison between analytical hierarchy process frequency ratio and logistic regression models abstract the purpose of this study is to compare the landslide susceptibility mapping models of logistic regression lr analytical hierarchy process ahp and frequency ratio fr applied in the central zab basin west azerbaijan iran eight factors were used for landslide susceptibility mapping including slope aspect land cover precipitation lithology and the distance to roads drainage and faults that affect the occurrence of landslides to get more precision speed and facility in our analysis all descriptive and spatial information was entered into gis system satellite images landsat etm and spot 5 are also used to prepare for land use and landslide inventory mapping respectively landslide events as used as dependant variable and data layers as independent variable making use of the correlation between these two variables in landslide susceptibility the three models are validated using the relative landslide density index r index and the receiver operating characteristic roc curves the predictive capability of each model was determined from the area under the relative operating characteristic curve and the areas under the curves obtained using the lr ahp and fr methods are 0 8941 0 8115 and 0 8634 respectively these results indicate that the lr and fr models are relatively good estimators of landslide susceptibility in the study area the interpretations of the susceptibility map reveal that precipitation lithology and slope played major roles in landslide occurrence and distribution in the central zab basin in general all three models were reasonably accurate the resultant maps would be useful for regional spatial planning as well as for land cover planning

assessment of sidewall erosion in large gullies using multi temporal dems and logistic regression analysis although in the last decades gully erosion has been a thriving research field few studies have specifically addressed the contribution and location of sidewall erosion processes in gullies in this paper sidewall erosion in some large gullies in a mediterranean area anoia penedes ne spain is mapped and assessed for two time intervals 1975 1995 and 1995 2002 using detailed digital elevation models derived from aerial photographs at a scale of 1 5000 to 1 7000 logistic regression analysis is applied to compute the probability of occurrence of gully sidewall erosion from terrain variables the results confirm the complex nature of sidewall processes whose intensity is most probably related to rainfall characteristics prolonged wet soil conditions in the period 1995 2002 together with the large and high intensity rainfall of an extreme event occurred on 10th june 2000 help to explain the different sediment production rates 16 0 4 mg ha 1 year 1 in 1975 1995 and 83 6 3 mg ha 1 year 1 in 1995 2002 the logistic regression analysis revealed that gully wall slope angle was the main factor controlling gully sidewall failure in gully walls with high slope angles tension crack development is the main process promoting wall collapse the application of the logistic regression model showed a high overall accuracy 87 but over 50 of commission and omission errors for the class of interest sidewall erosion in agreement with the variance explained by the model

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

hydrodynamics of carbonate fecal pellets abstract sand sized carbonate fecal pellets are a common to dominant constituent of many shallow marine tropical environments ovoid pellets 100 1000 in median diameter predominate pellets may be soft or hardened by intragranular micritization or cementation single grain settling of pellets collected from eight shallow marine environments in south florida and the bahamas permits calibration with the hydrodynamic behavior of quartz spheres well hardened carbonate pellets settle at rates equivalent to quartz spheres having a median diameter 70 percent to 100 percent of the pellet size soft carbonate pellets containing abundant silt settled as quartz spheres 90 to 30 percent in diameter soft carbonate pellets composed mainly of aragonite needle mud settled as quartz spheres 60 to 25 ercent in diameter from this data preliminary estimates can be made of the shear velocities necessary for entertainment of pellet or peloidal sands and the propensity of suspended versus bedload transport of different grain types and sizes

a comparison of gis based landslide susceptibility assessment of the satuk village yenice nw turkey by frequency ratio and multi criteria decision methods landslide is one of the most influential natural disasters that cause losses of life and property on a large scale to identify the landslide susceptible areas the layers of data showing different characteristics of the earth must be evaluated together in the course of evaluating data layers together the emerging technology of geographical information systems gis allows the collection processing and analysis of data the purpose of this study is to produce a landslide susceptibility map of the satuk village in the yenice district of the province of karabuk in the western black sea region where landslides causing frequent loss of life and property occur frequently in the area the slope lithology aspect elevation distance to river and distance to road parameters were considered as the parameters causing the landslides all of the parameters were standardized in a common scale using fuzzy membership functions then the contributions of each of these parameters for the landslide occurrence were investigated by frequency ratio and gis based multi criteria decision analysis and the weight values of the parameters were calculated the generated landslide susceptibility map is divided into five classes additionally the landslide inventory map was compared to the obtained landslide susceptibility maps to find out how well the constructed models fit the reality an overlap of 81 56 was found based on the multi criteria decision analysis method and an overlap of 89 96 was found based on the frequency ratio method the results showed that the frequency ratio method provides better results than the multi criteria decision analysis method considering the data used for the study area

reply to comments on anatomy of a late quaternary carbonate island constraints on timing and magnitude of sea level fluctuations west caicos turks and caicos islands bwi by wanless and dravis quat sci rev doi 10 1016 j quascirev 2020 106216 abstract we address concerns raised by wanless and dravis 2020 on our paper documenting the late quaternary evolution of west caicos island we negate the claim that omitting their paper dravis and wanless 2017 had any consequences for our interpretations we also provide reasoning and data to demonstrate that our interpretation of the quaternary stratigraphy of the island was derived from detailed field work and high resolution remote sensing data which was subsequently corroborated by aar and u th age dating control the opposite of the claim by wanless and dravis

selecting and weighting spatial predictors for empirical modeling of landslide susceptibility in the darjeeling himalayas india in this paper we created predictive models for assessing the susceptibility to shallow translational rocksliding and debris sliding in the darjeeling himalayas india by empirically selecting and weighting spatial predictors of landslides we demonstrate a two stage methodology 1 quantifying associations of individual spatial factors with landslides of different types using bivariate analysis to select predictors and 2 pairwise comparisons of the quantified associations using an analytical hierarchy process to assign predictor weights we integrate the weighted spatial predictors through multi class index overlay to derive predictive models of landslide susceptibility the resultant model for shallow translational landsliding based on selected and weighted predictors outperforms those based on all weighted predictors or selected and unweighted predictors therefore spatial factors with negative associations with landslides and unweighted predictors are ineffective in predictive modeling of landslide susceptibility we also applied logistic regression to model landslide susceptibility but some of the selected predictors are less realistic than those from our methodology and our methodology gives better prediction rates although previous predictive models of landslide susceptibility indicate that multivariate analyses are superior to bivariate analyses we demonstrate the benefit of the proposed methodology including bivariate analyses

active ooid growth driven by sediment transport in a high energy shoal little ambergris cay turks and caicos islands ooids are a common component of carbonate successions of all ages and present significant potential as paleoenvironmental proxies if the mechanisms that control their formation and growth can be understood quantitatively there are a number of hypotheses about the controls on ooid growth each offering different ideas on where and how ooids accrete and what role if any sediment transport and abrasion might play these hypotheses have not been well tested in the field largely due to the inherent challenges of tracking individual grains over long timescales this study presents a detailed field test of ooid growth hypotheses on little ambergris cay in the turks and caicos islands british overseas territories this field site is characterized by westward net sediment transport from waves driven by persistent easterly trade winds this configuration makes it possible to track changes in ooid properties along their transport path as a proxy for changes in time ooid size shape and radiocarbon age were compared along this path to determine in which environments ooids are growing or abrading ooid surface textures petrographic fabrics stable isotope compositions 13 c 18 o and 34 s lipid geochemistry and genetic data were compared to characterize mechanisms of precipitation and degradation and to determine the relative contributions of abiotic e g abiotic precipitation physical abrasion and biologically influenced processes e g biologically mediated precipitation fabric destruction through microbial microboring and micritization to grain size and character a convergence of evidence shows that active ooid growth occurs along the transport path in a high energy shoal environment characterized by frequent suspended load transport median ooid size increases by more than 100 m and bulk radiocarbon ages decrease by 360 yr westward along the 20 km length of the shoal crest lipid and 16s rrna data highlight a spatial disconnect between the environments with the most extensive biofilm colonization and environments with active ooid growth stable isotope compositions are indistinguishable among samples and are consistent with abiotic precipitation of aragonite from seawater westward increases in ooid sphericity and the abundance of well polished ooids illustrate that ooids experience subequal amounts of growth and abrasion in favor of net growth as they are transported along the shoal crest overall these results demonstrate that in the ambergris system the mechanism of ooid growth is dominantly abiotic and the loci of ooid growth is determined by both carbonate saturation and sediment transport mode microbes play a largely destructive rather than constructive role in ooid size and fabric

improving landslide susceptibility mapping using morphometric features in the mawat area kurdistan region ne iraq comparison of different statistical models abstract susceptibility mapping provides information about vulnerable locations and thus helps to potentially decrease infrastructure damage due to mass wasting during the past decades expansion of settlements into areas prone to landslides in iraq has highlighted the importance of accurate landslide susceptibility studies the main goal of this research is to implement selected morphometric parameters to improve prediction of landslide susceptibility in the zagros mountain region we used the mawat area in the kurdistan region ne iraq to test the added value of morphometric indicators sixteen morphometric factors mainly derived from a digital elevation model dem extracted using the stereo ability of the advanced spaceborne thermal emission and reflection radiometer aster satellite as well as geological and environmental predictive factors were appraised we evaluated and compared frequency ratio fr weight of evidence woe logistic regression lr and probit regression pr approaches in combination with morphometric indices to determine the landslide susceptibility ls the areas under the curve auc of the prediction rate curve prc relative landslide density index r index and true positive percentage tpp for the four models show that all models perform similarly and the focus should be on careful selection of the predictive factors which is far more important than the methods used results indicate that lithology and slope aspects are the more dominant factors that lead to detect possible occurrence of landslides furthermore this work demonstrates that the hypsometric integral performs better than the commonly used slope curvature as a predictor and thus increases the prediction accuracy of the susceptibility map we argue that the use of adequate morphometric parameters can increase the efficiency of the ls mapping in other regions of the world