modeling susceptibility to landslides using the weight of evidence approach western colorado usa abstract the paonia mcclure pass area of colorado is well known for active mass movements we examined 735 active shallow movement features including debris flows debris slides rock slides and soil slides in this area identification of the hazardous areas is a fundamental component of disaster management and an important basis for promoting safe human occupation and infrastructure development in landslide prone areas bayes theorem based on the weight of evidence woe was used to create a map of landslides that could be hazardous the modeling was accomplished by employing a geographical information system gis and a statistical package seventeen factors that cause landslides were measured and weighted using the woe method to create a map of areas susceptible to landslides the maps of weighted factors were summed on a pixel by pixel basis after performing chi square tests to determine factors that are conditionally independent of each other by combining factors that represent topography hydrology geology land cover and human influences six models were developed the performance of each model was evaluated by the distribution of the observed landslides the validity of the best map was checked against landslides which were not entered in the analysis the resulting map of areas susceptible to landslides has a prediction accuracy of 78

dynamic deformation of seguam island aleutian islands alaska 1993 2000 implications for magmatic and hydrothermal processes 1 the most recent volcanic eruption on seguam island was detected in december 1992 and lasted until july or august of 1993 a series of radar interferograms generated from imagery collected by the european space agency s ers 1 and ers 2 satellites are used here to map the spatial and temporal evolution of the deformation field from june of 1993 to september of 2000 this evolution consists of a coeruptive period of uplift surrounding the eruption two posteruptive subsidence signals centered within each of the two calderas on the island each of which lasted for 4 years after the end of the eruption and then uplift beneath the caldera on the eastern side of the island and the surrounding region from mid 1999 through the end of the time series in september 2000 the locations and magnitudes of the sources of the deformation are inferred from the interferometric synthetic aperture radar displacement data using an elastic half space earth model with multiple mogi point sources and a levenburg marquardt nonlinear inversion technique this inference reveals that the sources of subsidence are located within the upper 2 km of the earth s crust while the sources of uplift are located below 2 5 km the locations of dilatational sources are consistent with a model of the volcanic system where ascending magma accumulates below a density or structural boundary near 2 5 3 km depth the subsidence signals are most likely associated with cooling of shallow magmatic bodies emplaced during the 1992 1993 eruption however the possibility that they indicate a combination of magma cooling and depressurization of a hydrothermal system cannot be ruled out using the geodetic data alone implications for the long term evolution of the volcanic edifice are discussed

using multiple logistic regression and gis technology to predict landslide hazard in northeast kansas usa abstract landslides in the hilly terrain along the kansas and missouri rivers in northeastern kansas have caused millions of dollars in property damage during the last decade to address this problem a statistical method called multiple logistic regression has been used to create a landslide hazard map for atchison kansas and surrounding areas data included digitized geology slopes and landslides manipulated using arcview gis logistic regression relates predictor variables to the occurrence or nonoccurrence of landslides within geographic cells and uses the relationship to produce a map showing the probability of future landslides given local slopes and geologic units results indicated that slope is the most important variable for estimating landslide hazard in the study area geologic units consisting mostly of shale siltstone and sandstone were most susceptible to landslides soil type and aspect ratio were considered but excluded from the final analysis because these variables did not significantly add to the predictive power of the logistic regression soil types were highly correlated with the geologic units and no significant relationships existed between landslides and slope aspect

the evolution of the mecklenburg bay environment in the holocene in the light of multidisciplinary investigations of the sediment cores abstract multi proxy studies of the sediment cores and acoustic profiles from mecklenburg bay display a more detailed picture of the evolution of the environment in the holocene studies of diatoms geochemistry grain size and radiocarbon dating clearly reveal the age and character of freshwater and marine transgressions and regressions after the final regression of the baltic ice lake a local lake and swamp environment was recorded by peat gyttja sediments this environment existed until the ancylus lake transgression dated ca 10 500 cal bp during the ancylus lake period the area remained a shallow water lake transitional isolated from the main baltic basin the first slightly brackish marine inflows confirmed by the appearance of planktonic mesohalobous and halophilous diatoms were identified at the beginning of the initial littorina sea stage and dated ca 8800 cal bp the boundary between the ancylus lake and the initial littorina sea is marked by increasing contents of biogenic silica and iron the initial littorina sea stage was characterized by increasing mesohalobous and polyhalobous diatom forms and decreasing oligohalobous species the initial littorina sea environment was recorded as a slightly brackish reservoir sporadically affected by weak marine inflows the littorina transgression appeared in the mecklenburg bay at ca 7500 7700 cal bp and is reflected by the domination of polyhalobous diatoms increasing mean grain size biogenic silica and calcium and magnesium contents the initial littorina sea was a 1500 year long period in mecklenburg bay existing until the littorina transgression the main littorina transgression first appeared in mecklenburg bay around 7700 cal bp and after a few hundred years at around 7200 cal bp in the arkona basin

statistical models for slope instability classification abstract statistical models for reliable hazard assessment of landslides in a given area are presented the models are based on information theory and regression analysis information theory is a branch of probability in which the most significant feature is unpredictability and regression analysis is based on simple statistical theory both methods of statistical prediction have been applied to slope instability to provide cross validation of the results a fortran 77 program for computer aided assessment of the landslide hazard has been developed the program considers the factors affecting the slope instability and history of past landslides of the area as its input the program also calculates the information and regression value in a given area and classifies the area into different grades of instability a case study of landslide hazard assessment of a 66 km2 area in parts of the alkananda valley the gharwal himalaya is presented the factors considered in the analysis are angle and height of the slope rock type and geological structures such as faults and thrusts the results obtained are illustrated in the form of landslide hazard maps the predicted results are compared by the above methods

petrologic constraints on the spatial distribution of crustal magma chambers atka volcanic center central aleutian arc the atka volcanic center the largest modern central aleutian magmatic complex covers 360 km2 with an estimated eruptive volume of 200 km3 the oldest exposed rocks the old harbor series are a suite of basaltic andesite to dacite flows pyroclastic rocks and lahars of presumed tertiary age the youngest phase of activity on atka probably began 1 2 ma ago near the center of the present volcanic field and consists of basaltic and basaltic andesite flows which produced a large shield volcano atka volcano subsequent to this activity satellite vents formed along the margin of this structure collapse of the ancestral atka volcano produced a caldera 5 km in diameter and was accompanied by the eruption of a large dacitic flow big pink after caldera formation four major volcanic cones korovin mount kliuchef sarichef and konia grew around the margins of atka caldera this study focuses on the atka volcano korovin and mount kliuchef volcanic centers atka lavas range from basalt through dacite with all major volcanic vents erupting lavas spanning similar compositional ranges they are porphyritic with phenocrysts of plagioclase 25 36 olivine 0 4 3 6 or orthopyroxene 2 8 clinopyroxene 1 12 and a single fe ti oxide 0 2 hydrous phases are lacking even in the most evolved lavas two generations of plagioclase occur in the korovin suite but not in lavas from mount kliuchef korovin plagioclase also displays resorption surfaces and inclusion zones which are either absent in the phenocrysts of mount kliuchef lavas or very rare similarly clinopyroxene in korovin has reaction rims and abundant glass inclusions which are absent in the mount kliuchef lavas lavas erupted in the atka volcanic field vary from 47 to 66 sio2 although the complex is dominated volumetrically by basaltic lavas on major element harker diagrams mafic and intermediate atka volcano lavas form linear trends but the most siliceous lavas do not fall along these trends by contrast mount kliuchef lavas are compositionally bimodal whereas korovin samples range from 51 to 62 wt silica with intermediate lavas clustering around 55 sio2 incompatible trace element abundances of korovin lavas do not increase with silica content but those of atka volcano and mount kliuchef do on incompatible incompatible element diagrams the three suites behave very differently differences also exist between the ree characteristics of the three atka suites the petrographic and geochemical differences between the three suites suggest formation by markedly different crustal magmatic processes the characteristics of the atka volcano suite suggest formation of the basalt to dacite suite by crystal fractionation of an anhydrous phenocryst assemblage incompatible incompatible element trends suggest the mafic mount kliuchef lavas were also produced by crystal fractionation a conclusion supported by quantitative mass balance calculations the difference in slope between the atka volcano and mount kliuchef suites indicates however that there were significant differences in these fractionation schemes modeling as well as geochemical characteristics suggest that the mount kliuchef dacites are not the product of crystal fractionation they may represent 1 crustal melts 2 complete melts of siliceous lava produced during earlier magmatic stages or 3 residual liquids from the atka volcano magmatic system in contrast to these suites the korovin lavas could not have been formed by crystal fractionation rather the andesites are probably the result of mixing basaltic and dacitic magmas the atka data suggest 1 large volcanic centers may be supplied by a series of non communicating crustal magma chambers 2 local factors may be important in determining liquid lines of descent and 3 very different magmatic processes may occur in adjacent magma chambers if the complexity of the atka suite is a common feature of arc magmatic plumbing systems reconstructing differentiation processes requires analytical sample sets which are well constrained spatially and temporally

a gis based landslide susceptibility evaluation using bivariate and multivariate statistical analyses bivariate and multivariate statistical analyses were used to predict the spatial distribution of landslides in the cuyahoga river watershed northeastern ohio u s a the relationship between landslides and various instability factors contributing to their occurrence was evaluated using a geographic information system gis based investigation a landslide inventory map was prepared using landslide locations identified from aerial photographs field checks and existing literature instability factors such as slope angle soil type soil erodibility soil liquidity index landcover pattern precipitation and proximity to stream responsible for the occurrence of landslides were imported as raster data layers in arcgis and ranked using a numerical scale corresponding to the physical conditions of the region in order to investigate the role of each instability factor in controlling the spatial distribution of landslides both bivariate and multivariate models were used to analyze the digital dataset the logistic regression approach was used in the multivariate model analysis both models helped produce landslide susceptibility maps and the suitability of each model was evaluated by the area under the curve method and by comparing the maps with the known landslide locations the multivariate logistic regression model was found to be the better model in predicting landslide susceptibility of this area the logistic regression model produced a landslide susceptibility map at a scale of 1 24 000 that classified susceptibility into four categories low moderate high and very high the results also indicated that slope angle proximity to stream soil erodibility and soil type were statistically significant in controlling the slope movement

how wide is a road the association of roads and mass wasting in a forested montane environment a spatial data base of 1609 landslides was analysed using a geographic information system to determine landslide frequency in relation to highways a 126 km long transportation network in a 201km 2 area of humid tropical mountainous forested terrain in puerto rico was used in conjunction with a series of 20 buffer disturbance zones varying from 5 to 400 m in length measured perpendicular to the highways average landslide frequency in the study area at distances greater than 85 m from roads was about six landslides per square kilometre at distances of 85 m or less on either side of a highway landslide frequency was about 30 landslides per square kilometre on average this elevated disturbance rate affected 330 m 2 km 2 a 1 within the 170 m swath the mass wasting rate outside of the disturbance zone affected 40 m 2 km 2 a 1 these results indicate that the rate of mass wasting disturbance is increased from five to eight times in a 170 m wide swath along road corridors the lateral extent of the environmental impact of roads in the study area is greater than is commonly perceived the approach described herein demonstrates a simple method to assess the spatial association of mass wasting with highways 1997 by john wiley sons ltd

landslide susceptibility assessment in lianhua county china a comparison between a random forest data mining technique and bivariate and multivariate statistical models abstract landslides are an important natural hazard that causes a great amount of damage around the world every year especially during the rainy season the lianhua area is located in the middle of china s southern mountainous area west of jiangxi province and is known to be an area prone to landslides the aim of this study was to evaluate and compare landslide susceptibility maps produced using the random forest rf data mining technique with those produced by bivariate evidential belief function and frequency ratio and multivariate logistic regression statistical models for lianhua county china first a landslide inventory map was prepared using aerial photograph interpretation satellite images and extensive field surveys in total 163 landslide events were recognized in the study area with 114 landslides 70 used for training and 49 landslides 30 used for validation next the landslide conditioning factors including the slope angle altitude slope aspect topographic wetness index twi slope length ls plan curvature profile curvature distance to rivers distance to faults distance to roads annual precipitation land use normalized difference vegetation index ndvi and lithology were derived from the spatial database finally the landslide susceptibility maps of lianhua county were generated in arcgis 10 1 based on the random forest rf evidential belief function ebf frequency ratio fr and logistic regression lr approaches and were validated using a receiver operating characteristic roc curve the roc plot assessment results showed that for landslide susceptibility maps produced using the ebf fr lr and rf models the area under the curve auc values were 0 8122 0 8134 0 7751 and 0 7172 respectively therefore we can conclude that all four models have an auc of more than 0 70 and can be used in landslide susceptibility mapping in the study area meanwhile the ebf and fr models had the best performance for lianhua county china thus the resultant susceptibility maps will be useful for land use planning and hazard mitigation aims

a new technique for recognition of geological and geomorphological patterns in digital terrain models abstract we have developed a technique that recognizes monoclinal sedimentary strata showing strike ridge geomorphology and fluvial deposits from digital terrain models dtms this technique is efficient and reliable and may be expanded to analysis of other landforms techniques for rapid geomorphic analysis of dtms are becoming increasingly useful since digital stereoscopic spot data will soon be available worldwide our technique recognizes geomorphic elements in two steps first elementary objects including crests thalwegs and various slope types are classified from slope changes along n s e w nw se and ne sw profiles through pixels in the dtm image second grammatical pattern recognition is used to identify and map geomorphic forms from the succession of elementary objects

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

mid pleistocene basalt from the seguam volcanic center central aleutian arc alaska local lithospheric structures and source variability in the aleutian arc recent geophysical and tectonic studies make it possible to examine the relation between local structural and tectonic evolution of the modern aleutian arc and the sources and processes that produce the broad spectrum of aleutian basaltic lavas mid pleistocene basalt from the seguam island volcanic center in the central aleutian arc erupted through strongly extended arc crust contains 4 8 mgo is low in k2o 18 and is distinguished from aleutian basalt erupted through less extended crust by a low abundance of incompatible and rare earth elements ree and low sr and pb content the ba la 47 72 and pb la 0 7 1 5 ratios are high incompatible element ratios are variable and ree patterns cross one another the 87sr 86sr ratio 0 70365 0 00003 is the highest value obtained from the aleutian islands also 206pb 204pb 18 91 0 02 207pb 204pb 15 60 0 02 and 208pb 204pb 38 51 0 04 ratios are among the most radiogenic values known whereas the 143nd 144nd ratio 0 51297 0 00003 is among the lowest measured low abundances of incompatible elements high ba la and pb la ratios uniform sr nd and pb isotope ratios and high eruptive temperatures 1160 c suggest that basalt erupted at seguam ascends through extended subarc lithosphere without extensive chemical exchange with the upper mantle or lower crust partial melting of geochemically distinct portions of an isotopically uniform source region best explains observed geochemical characteristics trace element abundances rule out an eclogite source and suggest instead a peridotite dominated source with 5 10 of a subducted sediment component this peridotite may reside in the mantle wedge or in the amlia fracture zone afz of the pacific plate that was subducted beneath seguam 1 ma in addition the afz possibly enhanced the subduction of terrigenous sediment into the source region beneath seguam and this extra terrigenous component may explain the ba la pb la and sr nd and pb isotope ratios the distinctive composition of seguam basalt reflects a complex set of physical conditions including fracture zone subduction and intraarc extension that affected both the source region and thermo chemical history of magma ascent local structural and tectonic factors impact profoundly the nature of island arc magma sources and processes models that propose a common parental arc magma type or common processes on a global or arcwide scale are too generalized to explain the diversity actually observed in the aleutian arc

relationships between tectonic and geomorphological linear features in the guadix baza basin southern spain linear elements of the landscape of the guadix baza basin southern spain were identified from a landsat tm image three important lineament trends have been identified in the guadix baza basin the first is ne sw which is the dominant trend in the basin the second is nw se and the third is ene wsw these three trends are correlated to the major faults of the guadix baza basin the study of linear features by the analysis of satellite data has revealed a strong link between the buried tectonic structures and the morphological features appearing at the surface the distribution and density of lineaments explains much of the morphology of the land surface it is possible to reconstruct elements of the tectonic and denudational history of the region and show that during quaternary times lineaments controlled the sedimentation of the basin and the drainage pattern copyright 1999 john wiley sons ltd

landslide susceptibility mapping along kolli hills ghat road section india using frequency ratio relative effect and fuzzy logic models this article emphasizes landslide susceptibility mapping along ghat road of kolli hills tamil nadu india using frequency ratio relative effect and fuzzy gamma operator models with the help of remote sensing data and gis technique the purpose of the study is to generate compare and validate landslide susceptibility zones landslide inventory was done with data collected from the state highways department there are nine landslide influencing parameters such as slope gradient slope aspect slope curvature relief lithology land use and land cover proximity to road proximity to drainage and proximity to lineament analyzed with help of topo map existing geology map and satellite data to produce landslide susceptibility maps landslide susceptibility maps were generated by calculating relationship between the landslide influencing factors with past landslide locations using frequency ratio relative effect and fuzzy gamma operator models these landslide susceptibility maps were verified and compared using the existing landslide inventory data the prediction accuracy of frequency ratio model was 87 93 for fuzzy gamma operator model was 87 33 and for relative effect model it was 85 26 out of which the frequency ratio model provide maximum prediction accuracy on landslide susceptibility

the application of gis based logistic regression for landslide susceptibility mapping in the kakuda yahiko mountains central japan as a first step forward in regional hazard management multivariate statistical analysis in the form of logistic regression was used to produce a landslide susceptibility map in the kakuda yahiko mountains of central japan there are different methods to prepare landslide susceptibility maps the use of logistic regression in this study stemmed not only from the fact that this approach relaxes the strict assumptions required by other multivariate statistical methods but also to demonstrate that it can be combined with bivariate statistical analyses bsa to simplify the interpretation of the model obtained at the end in susceptibility mapping the use of logistic regression is to find the best fitting function to describe the relationship between the presence or absence of landslides dependent variable and a set of independent parameters such as slope angle and lithology here an inventory map of 87 landslides was used to produce a dependent variable which takes a value of 0 for the absence and 1 for the presence of slope failures lithology bed rock slope relationship lineaments slope gradient aspect elevation and road network were taken as independent parameters the effect of each parameter on landslide occurrence was assessed from the corresponding coefficient that appears in the logistic regression function the interpretations of the coefficients showed that road network plays a major role in determining landslide occurrence and distribution among the geomorphological parameters aspect and slope gradient have a more significant contribution than elevation although field observations showed that the latter is a good estimator of the approximate location of slope cuts using a predicted map of probability the study area was classified into five categories of landslide susceptibility extremely low very low low medium and high the medium and high susceptibility zones make up 8 87 of the total study area and involve mid altitude slopes in the eastern part of kakuda mountain and the central and southern parts of yahiko mountain

a data based landslide susceptibility map of africa abstract our understanding of the spatial patterns of landslides in africa is limited with available landslide studies typically focusing on only one or a few study areas moreover africa is clearly underrepresented in terms of available landslide inventories this study aims to produce a first continent wide landslide susceptibility map for africa calibrated with a well distributed landslide dataset we reviewed the literature on landslides in africa and compiled all available landslide inventories ca 10 800 landslides supplemented by additional landslide mapping using google earth imagery in underrepresented regions ca 7250 landslides this resulted in a dataset of approximately 18 050 landslides various environmental variables were investigated for their significance in explaining the observed spatial patterns of landslides to account for potential mapping biases in the dataset we used monte carlo simulations that selected different subsets of mapped landslides to test the significance of the considered environmental variables based on these analyses we constructed two landslide susceptibility maps for africa one for all landslide types and one excluding the known rockfalls in both maps topography is by far the most significant variable we evaluated the performance of the fitted multiple logistic regression models using independent subsets of landslides selected from the total dataset overall both maps perform very well in predicting intra continental patterns of landslides in africa and explain about 80 of the observed variance in landslide occurrence to further test the robustness and sensitivity to mapping biases we also modelled landslide susceptibility while excluding regions with arid climates as landslides in these environments are expected to be better preserved over time and therefore likely relatively overrepresented despite this potential bias the effect on the landslide susceptibility model is limited based on the constructed database and our analyses we further discuss potential research gaps for landslide prediction in africa and at continental scales for example analysis of the african countries mean landslide susceptibility shows a lack of landslide research in various countries prone to landsliding e g guinea gabon lesotho madagascar apart from the intrinsic value of this landslide susceptibility map as a natural hazard risk management tool the map and compiled database are highly promising for other applications for example we explored the potential significance of landslides as a geomorphic process by confronting our landslide susceptibility map with an available database of measured catchment sediment yield for 500 rivers in africa overall a significant positive but relatively weak relation between landslide susceptibility and sediment yield is observed

assessment of landslide susceptibility on the natural terrain of lantau island hong kong steep terrain and the high frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon in hong kong for example more than 800 slope failures were triggered by a rainstorm in november 1993 on lantau island hong kong maps of recent landslides interpreted from aerial photographs in combination with a geographical information system were used to evaluate the frequency and distribution of landslides with particular reference to such physical parameters as lithology slope gradient slope aspect elevation vegetation cover and proximity to drainage line all of which are considered to be influential in the occurrence of landslides a stepwise logistic regression model was obtained between landslide susceptibility and the above mentioned physical parameters the study area has been classified into five classes of relative landslide susceptibility namely very low low moderate high and very high based on this methodology

landslide susceptibility assessment what are the effects of mapping unit and mapping method landslide susceptibility assessment forms the basis of any hazard mapping which is one of the essential parts of quantitative risk mapping for the same study area different susceptibility maps can be achieved depending on the type of susceptibility mapping methods mapping unit and scale although there are various methods of obtaining susceptibility maps the efficiency and performance of each method should be evaluated in this study the effect of mapping unit and susceptibility mapping method on landslide susceptibility assessment is investigated when analyzing the effect of susceptibility mapping method logistic regression lr which is widely used in landslide susceptibility mapping and spatial regression sr which have not been used for landslide susceptibility mapping are selected the susceptibility maps with logistic and spatial regression models are obtained using two different mapping units namely slope unit based and grid based mapping units the procedure for investigation of effect of mapping unit on different susceptibility mapping methods is applied to kumluca watershed in bartin province of western black sea region turkey 18 factor maps are prepared for landslide susceptibility assessment in the study region geographic information systems and remote sensing techniques are used to create the landslide factor maps to obtain susceptibility maps and to compare the results the relative operating characteristics roc curve is used to compare the predictive abilities of each model and mapping unit and also the accuracy is evaluated depending on the observations made during field surveys by analyzing the area under the roc curve for grid based and slope unit based mapping units it can be concluded that sr model provide better predictive performance 0 774 in grids and 0 898 in slope units as compared to the lr model 0 744 in grids and 0 820 in slope units this result is also supported by the accuracy analysis for both mapping units the sr model provides more accurate result 0 55 for grids and 0 57 for slope units than the lr model 0 50 for grids and 0 48 for slopes the main reason for this better performance is that the spatial correlations between the mapping units are incorporated into the model in sr while this fact is not considered in lr model

sedimentary alkenone distributions reflect salinity changes in the baltic sea over the holocene the baltic sea has had a complex salinity history since the last deglaciation here we show how distributions of alkenones and their d values varied with past fluctuations in salinity in the baltic sea over the holocene by examining a holocene record 11 2 0 1 cal kyr bp from the arkona basin major changes in the alkenone distribution i e changes in the fractional abundance of the c37 4 me alkenone the c38 2 et alkenone and a c36 2 me alkenone the latter which has not been reported in the baltic sea previously correlated with known changes in salinity both alkenone distributions and hydrogen isotopic composition suggest a shift in haptophyte species composition from lacustrine to brackish type haptophytes around 7 7 7 2 cal kyr bp corresponding with a salinity change that occurred when the connection between the basin and the north sea was re established a similar salinity change occurred in the black sea previously published alkenone distributions and their d values from the black sea were used to reconstruct holocene changes in surface water salinity and hence it was shown that the unusual c36 2 alkenone dominates the alkenone distribution at salinities of 2 8 ppt g kg this information was used to corroborate the interpretations made about salinity changes from the data presented for the baltic sea low and variable salinity waters in the baltic sea over the holocene have led to a variable alkenone producing haptophyte community composition including low salinity adapted species hindering the use of the unsaturation ratios of long chain alkenones for sea surface temperature reconstruction however these alkenone based indices are potentially useful for studying variations in salinity regionally as well as in the past

assessment of landslide susceptibility for a landslide prone area north of yenice nw turkey by fuzzy approach regional landslide susceptibility assessments pose complex problems to solve these problems numerous approaches such as statistical analysis geotechnical engineering approach geomorphologic approach and fuzzy logic have been employed however all the available methods for regional landslide susceptibility assessments have some uncertainties due to a lack of knowledge and variability minimizing these uncertainties provides realistic approaches use of the fuzzy logic approach to produce a landslide susceptibility map of a landslide prone area in nw turkey is the main purpose of the present study for this purpose the study includes five main stages these being the preparation of a landslide inventory of the study area the application of factor analysis the extraction of fuzzy if then rules the use of a geographical information system and the control of the reliability of the resulting landslide susceptibility map slope angle slope aspect land use weathering depth water conditions and topographical elevation were considered as landslide conditioning factors for the study area a total of 23 if then rules was extracted from the field data employing these rules fuzzified index maps representing each parameter were obtained finally combining these maps the landslide susceptibility map of the area was prepared when compared with the landslide susceptibility map the landslides identified in the area were found to be located in the very high and high susceptibility zones as far as the performance of the fuzzy approach for processing is concerned the images appear to be quite satisfactory the zones determined on the map being zones of relative susceptibility

different landslide sampling strategies in a grid based bi variate statistical susceptibility model abstract this study had three aims the first was to assess the performance of the weights of evidence wofe landslide susceptibility model in areas that are very different in terms of size geoenvironmental settings and landslide types the second was to test the appropriate strategies to sample the mapped landslide polygon the final aim was to evaluate the performance of the method to changes in the landslide sample size used to train the model the method was applied to two areas the fella river basin eastern italian alps containing debris flows and buzau county romanian carpathians with shallow landslides the three landslide sampling strategies used were 1 the landslide scarp centroid 2 points populating the scarp on a 50 m grid and 3 the entire scarp polygon the highest success rates were obtained when sampling shallow landslides as 50 m grid points and debris flow scarps as polygons prediction rates were highest when using the entire scarp polygon method for both landslide types the sample size test using the landslide centroids showed that a sample of 104 debris flow scarps was sufficient to predict the remaining 941 debris flows in the fella river basin while 161 shallow landslides was the minimum required number to predict the remaining 1451 scarps in buzau county below these landslide sample thresholds model performance was too low however using more landslides than the threshold produced a plateau effect with little to no increase in the model performance rates

stress fields of the overriding plate at convergent margins and beneath active volcanic arcs tectonic stress fields in the overriding plate at convergent plate margins are complex and vary on local to regional scales volcanic arcs are a common element of overriding plates stress fields in the volcanic arc region are related to deformation generated by subduction and to magma generation and ascent processes analysis of moment tensors of shallow and intermediate depth earthquakes in volcanic arcs indicates that the seismic strain field in the arc region of many convergent margins is subhorizontal extension oriented nearly perpendicular to the arc a process capable of generating such a globally consistent strain field is induced asthenospheric corner flow below the arc region

autologistic modelling of susceptibility to landsliding in the central apennines italy in previous research a logistic regression of landslide occurrence on several explanatory variables was fitted and used to map landslide susceptibility for a small area in the central apennines italy here the spatial dependence or spatial correlation in the residuals from the fitted regression model was accounted for by inserting an autocovariate into the model the autocovariate was estimated by applying a gibbs sampler to the susceptibilities for neighbouring pixels as in any landslide susceptibility analysis accuracy was difficult to assess because of the requirement for data on future landslides however by comparing the ordinary logistic model to the autologistic model obtained on the same set of data it was possible to assess the influence of the autocovariate the autocovariate rendered the model simpler because several variables lost their significance and were therefore omitted from the model further areas of high landslide susceptibility estimated from the autologistic model were geographically clustered as one would expect and this may be advantageous in terms of i interpreting the model and ii displaying the results to non experts

composite transform convergent plate boundaries description and discussion abstract the leading edge of the overriding plate at an obliquely convergent boundary is commonly sliced by a system of strike slip faults this fault system is often structurally complex and may show correspondingly uneven strain effects with great vertical and translational shifts of the component blocks of the fault system the stress pattern and strain effects vary along the length of the system and change through time these margins are considered to be composite transform convergent ctc plate boundaries examples are given of structures formed along three ctc boundaries the aleutian ridge the solomon islands and the philippines the dynamism of the fault system along a ctc boundary can enhance vertical tectonism and basin formation this concept provides a framework for the evaluation of petroleum resources related to basin formation and mineral exploration related to igneous activity associated with transtensional processes

comparison of the implementation of rock engineering system and analytic hierarchy process methods upon landslide susceptibility mapping using gis a case study from the eastern achaia county of peloponnesus greece as landslides are very common in greece causing serious problems to the social and economic welfare of many communities the implementation of a proper hazard analysis system will help the creation of a reliable susceptibility map his will help local communities to define a safe land use and urban development the purpose of this study is to compare the implementation of two semi quantitative landslide assessment approaches using landslide susceptibility maps compiled in a gis environment the compared methods are rock engineering system res and the analytic hierarchy process ahp for the landslide susceptibility analysis the northeastern part of the achaia county was examined this area suffers from many landslides because of its neighborhood with the tectonically active corinthian gulf and its geological setting neogene sediments flysch and other bedrock formations with local overthrusts ten parameters were used in both methodologies and each one was separated into five categories ranging from 0 to 4 representing their specific conditions derived from the investigation of the landslides in the western part of the study area ranking area a layer map was generated for each parameter using gis while the weighting coefficients of each methodology were used for the compilation of res and ahp final maps of the eastern part of the study area validating area by examining these two maps it is revealed that even though both correctly show the landslide status of the second site the res map reveals a better behavior in the spatial distribution of the various landslide susceptibility zones

gis techniques and statistical models in evaluating landslide hazard geographical information systems gis and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard from a small drainage basin located in central italy relevant geological and geomorphological factors were collected and processed by applying gis technology in particular modules were used which both generate high fidelity digital terrain models and automatically partition the terrain into main slope units the resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope unit although not lacking drawbacks the method proved to be a feasible and cost effective approach to landslide susceptibility assessment and mapping

gis based landslide susceptibility mapping using analytical hierarchy process and bivariate statistics in ardesen turkey comparisons of results and confirmations abstract the ardesen area is prone to landslides because of the climate conditions geologic and geomorphologic characteristics of the region as in previous years in 2001 due to heavy rainfall there were many landslides resulting in damage and human casualties there is still a great danger of further landslides in the region therefore it is vitally important to prepare a landslide susceptibility map of the region in this study the analytical hierarchy process ahp the statistical index wi and weighting factor wf methods were used to produce and later compare three susceptibility maps for this purpose thematic layers including landslide inventory lithology weathering slope aspect land cover distance to stream drainage density and distance to road were used in this study area 98 of landslides occurred in highly or completely weathered units lithology weathering land cover and slope data layers were found to be important factors in the study area to confirm the practicality of the three susceptibility maps were compared with a landslide activity map containing 16 active landslide zones the outcome was that the active landslide zones do not completely fit into the high and very high susceptibility classes but 81 3 of these landslide zones fall into the high and very high susceptibility zones of the ahp method while this is 62 5 in the case of wi method and 68 8 with the wf method in spite of the results obtained in this study the development of a susceptibility map is usually determined by the needs and available resources the results showed that the ahp method gave a more realistic picture of the actual distribution of landslide susceptibility than the wi and wf methods

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

a reappraisal of earthquake focal mechanisms and active shortening in the zagros mountains of iran summary the zagros mountains of sw iran are one of the most seismically active intra continental fold and thrust belts on earth and an important element in the active tectonics of the middle east surface faulting associated with earthquakes is extremely rare and so most information about the active faulting comes from earthquakes we use long period teleseismic p and sh body waves to determine the orientation and depth of faulting in 16 new earthquakes and then evaluate and synthesize all the available teleseismic data on earthquake source parameters in the zagros we use this information to investigate the style and distribution of active faulting in the zagros and how it contributes to the n s shortening of the arabia eurasia collision when the data are ranked in quality and carefully evaluated simple patterns are seen that are not apparent when routine catalogue data are taken at face value an important change in the fault configuration occurs along strike of the belt in the nw overall convergence is oblique to the trend of the belt and the surface anticlines and is achieved by a spatial separation partitioning of the orthogonal strike slip and shortening components on separate parallel fault systems by contrast in the se overall convergence is orthogonal to the regional strike and achieved purely by thrusting in the central zagros between these two structural regimes deformation involves parallel strike slip faults that rotate about vertical axes allowing extension along the strike of the belt the overall configuration is similar to that seen in other curved shortening belts such as the himalaya and the java sumatra trench all the zagros earthquakes we have been able to check have centroids shallower than 20 km and are confined to the upper crust many of the larger earthquakes are likely to occur in the basement beneath the sedimentary cover which is active even beneath areas of known shallow structural decollement such as the dezful embayment the dominant style of shortening is high angle reverse faulting with dips 30 though some lower angle thrusting occurs in places active thrust and reverse faulting is relatively confined to the lower topography on the sw edge of the belt today and only strike slip faulting affects the higher topography profound vertical changes in structural and stratigraphic level indicate that a similar style of deformation was once active across the width of the simple folded belt but has progressively migrated sw over the last 5 ma there is no evidence for a seismically active structural decollement such as a low angle thrust beneath the zagros nor is there any seismic evidence for active subduction either beneath the zagros or beneath central iran instead the arabian margin seems to have shortened by distributed thickening of the basement only in the syntaxis of the oman line at the se end of the zagros is there any evidence for a low angle thrust of regional extent here earthquakes continue 50 km north of the zagros thrust line the geological suture between the arabian margin and central iran reaching depths of 30 km and may represent thrusting of arabian basement beneath central iran to this extent

analytic network process model for landslide hazard zonation various controlling factors such as lithology slope angle slope aspect landuse channel proximity etc are generally considered for the landslide hazard assessment although outer dependence of these parameters to a landslide is inevitably taken into account inter dependence among the factors is seldom addressed analytic network process anp is the multi criteria decision making mcdm tool which takes into account such a complex relationship among parameters in this research an anp model for landslide susceptibility is proposed priority weights for each parameter controlling the landslide were determined and a hazard map was prepared of an area in a fragile mountainous terrain in the eastern part of nepal the data used in the example were derived from published sources aerial photographs and a topographic map however the procedures developed can readily incorporate additional information from more detailed investigations

geomorphological and historical data in assessing landslide hazard traditionally earth scientists assess landslide occurrence on the basis of geomorphological investigations carried out through aerial photograph interpretation and eldwork conversely local administrators primarily evaluate the impact of natural catastrophes such as landsliding on the basis of historical records and data owing to the substantial difference in the structure and spatial density of these two types of information it is dif cult to compare them directly and few investigators have attempted this we compared landslide information derived from geomorphological mapping and historical data in a pilot area the staffora river basin northern italy to do this we generated two multivariate statistical models where the dependent variable was either the mapped landslide deposits geomorphological model or the historical sites affected by landslide induced damage historical model by quantitatively comparing these two model maps we demonstrate that the geomorphological model performs better in terms of percentage of terrain units correctly predicted as stable or unstable the historical model underestimates landslide hazard mainly where human structures are lacking however it highlights slopes where landslide movements take place with a high frequency at the temporal scale of human life hence the joint use of these two models may facilitate the knowledge of the overall instability conditions of a given region and the identi cation of the landslides that are most frequently reactivated copyright 2003 john wiley sons ltd

susceptibility assessments of shallow earthflows triggered by heavy rainfall at three catchments by logistic regression analyses abstract sometimes regional meteorological anomalies trigger different types of mass movements in may 1998 the western black sea region of turkey experienced such a meteorological anomaly numerous residential and agricultural areas and engineering lifelines were buried under the flood waters besides the reactivation of many previously delineated landslides thousands of small scale landslides mostly the earthflow type occurred all over the region the earthflows were mainly developed in flysch type units which have already presented high landslide concentrations in this study three different catchments namely agustu egerci and kelemen were selected because they have the most landslide prone geological units of the region the purposes of the present study are to put forward the spatial distributions of the shallow earthflows triggered to describe the possible factors conditioning the earthflows and to produce the shallow earthflow susceptibility maps of the three catchments the unique condition units ucu were employed during the production of susceptibility maps and during statistical analyses the unique condition units numbered 4052 for the agustu catchment 13 241 for the egerci catchment and 12 314 for the kelemen catchment the earthflow intensity is the highest in the agustu catchment 0 038 flow ucu and lowest in the egerci catchment 0 0035 flow ucu logistic regression analyses were also employed however during the analyses some difficulties were encountered to overcome the difficulties a series of sensitivity analyses were performed based on some decision rules introduced in the present study considering the decision rules the proper ratios of ucu free from earthflow 0 ucu including the earthflow 1 for the agustu egerci and kelemen catchments were obtained as 3 6 and 5 respectively also a chart for the proper ratio selection was developed the regression equations from the selected ratios were then applied to the entire catchment and the earthflow susceptibility maps were produced the landslide susceptibility maps revealed that 15 of the agustu catchment 8 of the egerci catchment and 7 of the kelemen catchment have very high earthflow susceptibility and most of the earthflows triggered by the may 1998 meteorological event were found in the very high susceptibility zones

darss sill as a biological border in the fossil record of the baltic sea evidence from diatoms abstract biostratigraphical and palaeoecological analyses of cores along a transect from femer belt to the arkona basin reveal that north sea waters began to enter the western baltic sea between 8600 and 8400 calibrated years bp studies of diatoms indicate that mecklenburg bay was characterised by slightly brackish water conditions between 8400 and 8000 cal years bp at around 8000 cal years bp increasing salinity is indicated by a strong dominance of the diatoms paralia sulcata and dimeregramma minor some centuries later another diatom assemblage appeared and became dominant in mecklenburg bay this assemblage includes hyalinella lateripunctata and pravifusus hyalinus species typical of shallow water areas along the atlantic coast today at this time the first marine molluscs made their appearance the oldest shell of a marine mollusc found in our material is dated to 7600 cal years bp the associated assemblage that includes adult specimens of the gastropod aporrhais pespelicani indicates higher salinities than today during the littorina sea stage a marine diatom flora with p sulcata catenula adhaerens and d minor crossed the darss sill and became widely distributed in the arkona basin pomeranian bay and the baltic sea proper in contrast taxa indicative of the hyalinella lateripunctata p hyalinus assemblage are only found west of the darss sill in femer belt and mecklenburg bay apparently the darss sill threshold has been acting as an important salinity border from around 7800 cal years bp until today

gis based landslide susceptibility for arsin yomra trabzon north turkey region the purpose of this study is to assess the susceptibility of landslides around yomra and arsin towns near trabzon in northeast of turkey using a geographical information system gis landslide inventory of the area was made by detailed field surveys and the analyses of the topographical map the landslide triggering factors are considered to be slope angle slope aspect distance from drainage distance from roads and the weathered lithological units which were called as geotechnical units in the study idrisi and arcgis packages manipulated all the collected data logistic regression lr and weighted linear combination wlc statistical methods were used to create a landslide susceptibility map for the study area the results were assessed within the scope of two different points a effectiveness of the methods used and b effectiveness of the environmental casual parameters influencing the landslides the results showed that the wlc model is more suitable than the lr model regarding the casual parameters geotechnical units and slopes were found to be the most important variables for estimating the landslide susceptibility in the study area

intra arc extension and magmatic evolution in the central aleutian arc alaska new geologic petrologic and sr isotope data from seguam island alaska reveal substantial variation in the composition of magmas of the central aleutian arc the data indicate that variable magmatic processes occur along the strike of the arc seguam is situated on extended arc crust and has erupted voluminous basalt and dacite in contrast to basalt from adjacent volcanic centers atop unextended crust which evolved by polybaric open system crystallization seguam lavas crystallized at shallow levels under closed system conditions seguam basalt therefore better reflects the character of its source materials than basalt erupted through unextended arc crust the authors conclude that along arc differences in the nature of crystallization were facilitated by changes in the thermal and density structure of the subarc lithosphere caused by intra arc extension

a gis based approach for gully erosion susceptibility modelling using bivariate statistics methods in the ourika watershed morocco gully erosion is an important environmental issue with severe impacts this study aimed to characterize gully erosion susceptibility and assess the capability of information value infval and frequency ratio fr models for its spatial prediction in ourika watershed of the high atlas region of morocco these two bivariate statistical methods have been used for gully erosion susceptibility mapping by comparing each data layer of causative factor to the existing gully distribution weights to the gully causative factors are assigned based on gully density gullies have been mapped through field surveys and google earth high resolution images lithofacies land use slope gradient length slope aspect stream power index topographical wetness index and plan curvature were considered predisposing factors to gullying the digitized gullies were randomly split into two parts sixty five percent 65 of the mapped gullies were randomly selected as training set to build gully susceptibility models while the remaining 35 cases were used as validation set for the models validation the results showed that barren and sparse vegetation lands and slope gradient above 50 were very susceptible to gully erosion the roc curve was used for testing the accuracy of the mentioned models the analysis confirms that the fr model auc 80 61 shows a better accuracy than infval model auc 52 07 the performance of the gully erosion susceptibility map constructed by fr model is greater than that of the map produced by infval model the findings proved that gis based bivariate statistical methods such as frequency ratio model could be successfully applied in gully susceptibility mapping in morocco mountainous regions and in other similar environments the produced susceptibility map represents a useful tool for sustainable planning conservation and protection of land from gully processes

a comparative study of dempster shafer and fuzzy models for landslide susceptibility mapping using a gis an experience from zagros mountains sw iran abstract a catchment area at the zagros mountains nw shiraz iran is selected as a test site to comparing the output results of the dempster shafer d s and fuzzy models in landslide hazard mapping lithology slope angle slope aspect land cover and soil depth were considered as landslide causal factors the factor maps were input into a gis and a modified landslide hazard evaluation factor mlhef rating and fuzzy membership functions as well as belief function values were assessed for each class of the factor maps the fuzzy sum product and gamma combination approaches were examined and output maps were assessed based on the known landslides the outputs of fuzzy sum and product combination rules were not reasonable because these approaches classified the area into very high or very low susceptibility zones respectively which were not compatible to the field and factor maps criteria a value of 0 94 yielded the most reliable susceptibility for landslides overlay of the known landslides with the output favorability map showed that the identified landslides were located in the high and very high susceptible zones the output results of the dempster shafer model plausibility belief and uncertainty images were also evaluated based on the known landslides the results of this approach revealed that although it was expected that most of the known landslides correspond the plausibility or the belief map only a few of them supported the case and some landslides were coincided into the disbelief or uncertainty maps it is concluded that in comparison to the fuzzy model the d s model obtains less reliable results for landslide hazard mapping since the belief functions were assigned based on the fuzzy membership functions this might be due to the integration equations used by the model or the number of evidence maps used as input layers

a comparative study of frequency ratio weights of evidence and logistic regression methods for landslide susceptibility mapping sultan mountains sw turkey abstract this study evaluated and compared landslide susceptibility maps produced with three different methods frequency ratio weights of evidence and logistic regression by using validation datasets the field surveys performed as part of this investigation mapped the locations of 90 landslides that had been identified in the sultan mountains of south western turkey the landslide influence parameters used for this study are geology relative permeability land use land cover precipitation elevation slope aspect total curvature plan curvature profile curvature wetness index stream power index sediment transportation capacity index distance to drainage distance to fault drainage density fault density and spring density maps the relationships between landslide distributions and these parameters were analysed using the three methods and the results of these methods were then used to calculate the landslide susceptibility of the entire study area the accuracy of the final landslide susceptibility maps was evaluated based on the landslides observed during the fieldwork and the accuracy of the models was evaluated by calculating each model s relative operating characteristic curve 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 frequency ratio logistic regression and weights of evidence methods are 0 976 0 952 and 0 937 respectively these results indicate that the frequency ratio and weights of evidence models are relatively good estimators of landslide susceptibility in the study area specifically the results of the correlation analysis show a high correlation between the frequency ratio and weights of evidence results and the frequency ratio and logistic regression methods exhibit correlation coefficients of 0 771 and 0 727 respectively the frequency ratio model is simple and its input calculation and output processes are easily understood the interpretations of the susceptibility map reveal that geology slope steepness slope aspect and elevation played major roles in landslide occurrence and distribution in the sultan mountains the landslide susceptibility maps produced from this study could therefore assist planners and engineers during development and land use planning

on the causes for salinity variations in the baltic sea during the last 8500 years 1 the baltic sea became connected to the open sea about 8500 years b p and that marked the beginning of the still continuing litorina sea stage there have since been significant long term variations of the salinity from a maximum of some 10 15 to the present of 7 8 the salinity variations have been known since the beginning of the twentieth century and various mechanisms have been proposed to explain these however so far no one has actually tried to quantify and thereby rank the relative importance of the different proposed mechanisms in this paper we used a simple oceanographic model to quantify the impact of changes in cross sectional areas of the inlets to the baltic we found that such changes cannot explain the full variation of the salinity we propose that the remaining salinity variations 0 5 5 are explained by changes in net freshwater input in the range 15 60 the calculated variations in the freshwater supply are in large coherent with known variations of the northern european climate we show that other possible factors as increased mixing frontal displacements higher deep water salinity and larger depths in kattegat and larger oscillating flows across the sills due to increased sea level variability are less likely to have made substantial contributions to the salinity variations in the baltic sea

prediction of landslide susceptibility using rare events logistic regression a case study in the flemish ardennes belgium abstract in this article a statistical multivariate method i e rare events logistic regression is evaluated for the creation of a landslide susceptibility map in a 200 km2 study area of the flemish ardennes belgium the methodology is based on the hypothesis that future landslides will have the same causal factors as the landslides initiated in the past the information on the past landslides comes from a landslide inventory map obtained by detailed field surveys and by the analysis of lidar light detection and ranging derived hillshade maps information on the causal factors e g slope gradient aspect lithology and soil drainage was extracted from digital elevation models derived from lidar and from topographical lithological and soil maps in landslide affected areas however we did not use the present day hillslope gradient in order to reflect the hillslope condition prior to landsliding the pre landslide hillslope was reconstructed and its gradient was used in the analysis because of their limited spatial occurrence the landslides in the study area can be regarded as rare events rare events logistic regression differs from ordinary logistic regression because it takes into account the low proportion of 1s landslides to 0s no landslides in the study area by incorporating three correction measures the endogenous stratified sampling of the dataset the prior correction of the intercept and the correction of the probabilities to include the estimation uncertainty for the study area significant model results were obtained with pre landslide hillslope gradient and three different clayey lithologies being important predictor variables receiver operating characteristic roc curves and the kappa index were used to validate the model both show a good agreement between the observed and predicted values of the validation dataset based on a qualified judgement the created landslide susceptibility map was classified into four classes i e very high high moderate and low susceptibility if interpreted correctly this classified susceptibility map is an important tool for the delineation of zones where prevention measures are needed and human interference should be limited in order to avoid property damage due to landslides

frequency and spatial distribution of landslides in a mountainous drainage basin western foothills taiwan maps from 1904 and 1915 and air photographs from 1963 1980 1985 1993 and 1996 provide a record of landslide incidence in a 92 1 km2 drainage basin a headwater tributary of the cho shui river in taiwan interpretation of landslide patterns from the early maps indicate that in four sub basins 36 km2 structural geological factors control chronic landsliding regularly reactivated by intense rains within these four sub basins all later air photographs reveal a continuing high incidence of landslides with landslide densities of 3 11 ha km2 air photographs taken in 1963 following extensive logging in 1985 following highway construction and in 1996 following the very large typhoon herb event demonstrate the short term effects of disturbance in these structurally weak sub basins air photographs from 1980 and 1993 demonstrate recovery of the land surface from logging and highway construction impacts respectively for the adjacent sub basins 56 km2 two modes of response to perturbations were identified six sub basins 48 km2 showed direct response to logging road construction and typhoon herb and five sub basins 8 km2 were more buffered and showed some lagged responses even this last category of sub basins is more active than the average for taiwan where the mean landslide density is 0 84 ha km2 it is proposed that for the 92 1 km2 hoshe basin the formative event sensu brunsden z geomorphol suppl 79 1990 1 is one that produces approximately 200 ha of landslides a value that has been equaled or exceeded in each of the periods of study 1963 1980 1980 1985 1985 1993 and 1993 1996 logging activity major road construction and extreme typhoon and earthquake events produce short term acceleration of landslide incidence in principle recovery rates of the land from pulsed perturbations of about 20 years for logging activity and about 8 years for major road construction may also be suggested

anthropogenically accelerated mass movement kulu valley himachal pradesh india abstract a devastating landslide occurred on 12 september 1995 near luggar bhatti kulu himachal pradesh and killed 65 people an estimated 0 96 106 m3 of unconsolidated mass slid sse down the terminal part of a thick alluvial fan of quaternary age on the left bank of the beas river about 0 03 106 m3 of dislodged material formed a 15 m high and 150 m long hump at the bottom of the failed slope a shallow sag pond developed in the rear the slide occurred after heavy rains on 3 6 september in the region when the beas rose to a bankfull position factors involved in this toppling cum debris slide include steep slope continuous seepage with high pore water pressure in unconsolidated material a road cut obliterating the foot of the fan slope and impinging by the beas river during the flood a survey in the area showed that a variety of mass movement processes were triggered by the heavy rains in september the most predominant being a series of slope failures on the outside of meander loops and bank erosion caused by turbulence of the overflowing beas river extensive damage was sustained by national highway 21 nh 21 a bridge ramp near bhuntar a suspension bridge at kulu and two other bridges upstream most damage occurred in the manali area where massive buildings were washed away by the flash flood this paper examines the factors and processes responsible for triggering widespread mass movement and related damages in the kulu valley whereas some smaller events occurred in the early and middle part of this century the recurrence and intensity of mass movements are recent phenomena attributed mainly to escalating socio economic development growth of tourism and population pressure some long term policy is suggested for mitigation of landslides and other denudational processes in relation to impelling human factors

multidisciplinary investigations in evaluating landslide susceptibility an example in the serchio river valley italy abstract the proposed experimental study is aimed at contributing to the landslide susceptibility evaluation using a multidisciplinary approach geological geomorphological and geo engineering survey together with multivariate statistical analysis and gis technique it is included in a wider research project aimed at defining the landslide hazard in the area of the map no 250 castelnuovo di garfagnana 1 50 000 scale this study is based on the realization of a landslides inventory map and statistical data analysis using probabilistic methods the methodology applied in ranking slope instability proceeded step by step at first geomorphologic investigation was performed in order to realize a landslide inventory map a gis database was created to collect the characteristics related to landslides geometry type of movement and state of activity geo engineering survey and characterization with in situ and laboratory tests allowed assessing rock mass classification and geotechnical properties of soils texture and consistency the statistical approach for evaluating the landslide susceptibility is based on the assumption that the landslide probability for the currently landslides free areas could be evaluated studying the conditions which led to past and present instability a set of environmental factors thought to be related to landslides were analysed and their spatial distribution organized in different layers then gis supported spatial analysis conditional and multivariate analysis allowed to calculate the connections between instability factors and landslide distribution this step evolved towards two distinct statistical methods both indirect and quantitative leading to a classification of the land surface in some different susceptibility domains conditional analysis was applied to a particular type of terrain unit named unique condition unit ucu that is a unique combination of the instability factors the computer aided evaluation of the landslide index within each ucu represents the probability of landslide occurrence according to bayes statistical concept multivariate analysis was applied to the same set of instability factors but to a different type of terrain unit the grid cell the results showed a quantitative response more reliable about the effectiveness of each instability factors with the possibility of verifying their statistical significance

landslide characteristics and slope instability modeling using gis lantau island hong kong steep terrain and high a frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon in hong kong this paper reports on the use of a geographical information systems gis database compiled primarily from existing digital maps and aerial photographs to describe the physical characteristics of landslides and the statistical relations of landslide frequency with the physical parameters contributing to the initiation of landslides on lantau island in hong kong the horizontal travel length and the angle of reach defined as the angle of the line connecting the head of the landslide source to the distal margin of the displaced mass are used to describe runout behavior of landslide mass for all landslides studied the horizontal travel length of landslide mass ranges from 5 to 785 m with a mean value of 43 m and the average angle of reach is 27 7 this gis database is then used to obtain a logistic multiple regression model for predicting slope instability it is indicated that slope gradient lithology elevation slope aspect and land use are statistically significant in predicting slope instability while slope morphology and proximity to drainage lines are not important and thus excluded from the model this model is then imported back into the gis to produce a map of predicted slope instability the results of this study demonstrate that slope instability can be effectively modeled by using gis technology and logistic multiple regression analysis

a petrologic re investigation of the adak volcanic center central aleutian arc alaska the adak volcanic center is located in the central part of the aleutian arc and consists of three main volcanic vents andrew bay volcano the oldest center has been mostly removed by erosion the next youngest vent mount adagdak was built in three major volcanic stages whereas mount moffett the largest volcanic edifice consists of a main cone and a parasitic cone each with several magmatic phases adak is unique compared to other modern aleutian volcanic centers in that it contains two xenolith suites conrad and kay 1984 debari et al 1987 one suite consisting predominantly of mafic xenoliths occurs on mount moffett whereas an assemblage of ultramafic and mafic xenoliths is found on mount adagdak lavas erupted at adak span the compositional range from 48 4 to 65 0 wt sio2 and are characterized by significant variations in al2o3 mgo sr ni and cr on harker diagrams this variability produces compositional trends with significant scatter the adak suite has total ree contents that vary from 32 to 154 ppm but do not correlate systematically with silica layb n ratios range from 2 41 to 21 72 with the majority of lavas between 2 41 and 6 06 on process identification diagrams the adak suite plots as steeply sloping trends that contrast with the horizontal patterns of most other aleutian centers measured isotopic ranges are large and nearly equal to those for the entire arc although they span similar silica ranges subtle geochemical and isotopic differences distinguish the different volcanic vents of adak on mount moffett a geochemically and isotopically distinct group of andesites 55 5 57 9 sio2 the mafic andesites occur on its ne flank these lavas have elevated mgo ni and cr but are depleted in al2o3 relative to other mount moffett andesites with similar silica they also have more heterogeneous ree abundances and isotopic ratios than most of the other andesites significant compositional differences exist between adak and the other volcanic centers of the central aleutian arc although these differences are characteristic of all geochemical systems they are greatest for major and rare earth elements and isotopic ratios the lack of coherent relationships on major and trace element harker diagrams the isotopic variability as well as the steeply sloping trends on ree process identification diagrams suggest that the adak volcanic suite was not formed predominantly by closed system crystal fractionation but must be the product of a complex open system process es the significant isotopic variability displayed by the suite suggests that contamination by an isotopically distinct contaminant must also have been an important petrologic component in the evolution of the suite ree data are also suggestive of a role for magma mixing such a complex petrologic evolution is consistent with an immature lithospheric plumbing system based on ree systematics the xenolith suites of adak cannot as previously proposed be related to the host lavas or the rest of the adak suite through crystal fractionation schemes rather they are probably accidental fragments derived from various depths along lithospheric conduits in light of their relation to xenolith bearing units the mafic andesites of adak presumably represent hybrid magmas formed during the interaction of ascending magmas with lithospheric wall rock they are therefore characteristic of immature volcanic centers and unlikely to be related directly to the magmatic processes responsible for the generation of primary arc magmas because of the close proximity of the vents and the subtle compositional differences between their lavas the adak volcanic center was probably supplied by a single deep lithospheric plumbing system that fed separate crustal magma chambers the absence of historic volcanic activity on adak suggests this plumbing system was abandoned before complete conduit development this decline in magmatism may reflect a re adjustment of volcano spacing within this part of the aleutian arc

lidar supported prediction of slope failures using an integrated ensemble weights of evidence and analytical hierarchy process the present study investigates a potential application of different resolution topographic data obtained from airborne lidar and an integrated ensemble weight of evidence and analytic hierarchy process woe ahp model to spatially predict slope failures previously failed slopes of the pellizzano italy were remotely mapped and divided into two subsets for training and testing purposes 1 2 5 10 15 and 20 m topographic data were processed to extract nine terrain attributes identified as conditioning factors for landslides slope degree aspect altitude plan curvature profile curvature stream power index topographic wetness index sediment transport index and topographic roughness index landslide slope failure susceptibility maps were produced using a single woe model 1 an ensemble woe ahp model that used all conditioning factors model 2 and an ensemble woe ahp model that only used highly nominated conditioning factors model 3 the validation results proved the efficiency of high resolution 5 m topographic data and the ensemble model particularly when all factors were used in the modeling process model 2 the average success rates and prediction rates for model 2 that used 5 m resolution datasets were 84 26 and 82 78 respectively the finding presented in this paper can aid in planning more efficient lidar surveys and the handling of large datasets and in gaining a better understanding of the nature of the predictive models

spatio temporal patterns of historical shallow landslides in a volcanic area mt aso japan abstract the evaluation of spatially and temporally distributed records of translational shallow landslides in heterogeneous watersheds provides insights needed to understand disastrous processes recurrent slope instability events occurred between 1953 and 1998 in two watersheds of mt aso western japan this paper investigates 1 the spatio temporal characteristics of translational shallow landslides dimensions numbers densities and area subjected to failure observed at a particular location 2 dem based landform characteristics elevation slope angles curvatures and their control on landslide distribution and 3 rainfall characteristics the evaluation of the landslide history consequences and characteristics of spatially and temporally distributed landslides are based on the series of inventory maps for years 1954 1977 1990 and 1998 geologically the watersheds consist of pyroxene olivine andesite basalt lava pyroclastics deposits gravel sand and clay deposits originated from takadake nekodake and washigamine volcanoes during 45 years 1953 1998 a total of 619 and 976 numbers of shallow landslides have been recognized in the sakurakigawa and furuegawa watersheds respectively repeated sliding denuded a total surface area of 0 372 km 2 in the sakurakigawa watershed representing 35 of the watershed area similarly slides denuded a total of 0 534 km 2 in the furuegawa watershed representing 12 of the watershed area for example storm events of june 1953 and july 1990 with rainfall intensities of 49 and 61 mm h 1 respectively triggered numerous landslides about 25 and 47 of sakurakigawa and furuegawa watersheds respectively still bears the potential to produce landslides landslides were commonly observed where thick unconsolidated tephra layers and pyroclastics rocks overlain by thin tephra bed existed and for a slope inclination range of 30 35

littorina and post littorina sedimentological processes in the odra channel in light of multidisciplinary investigations of a sediment core pomeranian bay southern baltic sea abstract a multi proxy study was performed on a gravity core supplemented by acoustics profiles and new radiocarbon dates of macrofossils found in the sedimentation history of the odra channel during the holocene the channel is located in the western part of pomeranian bay and was shaped by a pre odra river that flowed northwest along the peene valley and the eastern part of rugen island during a drop in yoldia sea level the acoustic profiling enabled identification of glacial till the baltic ice lake and littorina sediments the studied core penetrated only marine sediments deposited during littorina and post littorina stages and was the subject of grain size geochemical and diatom analyses the age of appearance of a marine environment in the studied area was estimated at 7200 yrs bp the performed studies enabled division of the core into three phases of environmental evolution the littorina i phase occurred during the time span 7200 6000 yrs bp and is described as a shallow water brackish basin with a low rate of sea level rise and favourable conditions for biogenic production the littorina ii phase dated at 6000 3800 yrs bp reflects a deep marine environment with relatively high salinity and greater current velocity and the last phase post littorina covered the last 3800 yrs bp and turned out to be a strongly energetic environment with decreasing salinity the change from littorina ii to post littorina phase correlates clearly with a change in the acoustic reflection core analyses could be associated with extreme stormy cold events known as bond events dated at 5900 5500 yrs bp and 4200 yrs bp evidencing the final destruction of the odra bank barrier

landslide hazard zonation using analytical hierarchy process along national highway 3 in mid himalayas of himachal pradesh india landslide zonation studies emphasize on preparation of landslide hazard zonation maps considering major instability factors contributing to occurrence of landslides this paper deals with geographic information system based landslide hazard zonation in mid himalayas of himachal pradesh from mandi to kullu by considering nine relevant instability factors to develop the hazard zonation map analytical hierarchy process was applied to assign relative weightages over all ranges of instability factors of the slopes in study area to generate landslide hazard zonation map layers in geographic information system were created corresponding to each instability factor an inventory of existing major landslides in the study area was prepared and combined with the landslide hazard zonation map for validation purpose the validation of the model was made using area under curve technique and reveals good agreement between the produced hazard map and previous landslide inventory with prediction accuracy of 79 08 the landslide hazard zonation map was classified by natural break classifier into very low hazard low hazard moderate hazard high hazard and very high landslide hazard classes in geographic information system depending upon the frequency of occurrence of landslides in each class the resultant hazard zonation map shows that 14 30 of the area lies in very high hazard zone followed by 15 97 in high hazard zone the proposed model provides the best fit classification using hierarchical approach for the causative factors of landslides having complex structure the developed hazard zonation map is useful for landslide preparedness land use planning and social economic and sustainable development of the region

environmental evolution of western baltic sea in the holocene in the light of multidisciplinary investigations of sediments cores from arkona basin abstract a multidisciplinary investigation performed on gravity cores supplemented by a new radiocarbon dating of macrofossils outlined the environmental evolution of arkona basin in the holocene studies comprising the analysis of diatoms geochemistry grain size and radiocarbon dating clarified the knowledge about the age and environmental changes during freshwater and marine transgressions and regressions the acoustic profiling method allowed proper interpretation of the analysis results from sediment cores and created a proper lithostratigraphic model of the investigated basin baltic ice lake and yoldia sea sediment layers were identified acoustically and cores penetrated the final regression surface of the baltic ice lake the analyses of cores concentrated on ancylus lake and littorina sea sediments two phases of the ancylus lake stage were identified the peaks of loss on ignition in the cores observed as a strong acoustic reflector were identified as a marker of ancylus lake regression between the first high water level phase and the second shallow water phase the age of onset of littorina transgression was estimated at around 7000 7200 cal bp and was younger than some previous estimations the retrieved age confirmed the suggestion that the marine environment appeared first in mecklenburg bay and then after a few hundred years in arkona basin as an intensive transgression the appearance of littorina sea revealed a fast shift of the environment from lacustrine to marine the first phase of the littorina stage was recognised as a rapidly increasing water level and high energy environment the second showed rapidly increasing salinity in the calmer conditions of sedimentation

use of fuzzy relations to produce landslide susceptibility map of a landslide prone area west black sea region turkey abstract preparation of landslide susceptibility maps is important for engineering geologists and geomorphologists however due to complex nature of landslides producing a reliable susceptibility map is not easy for this reason many procedures have been used to produce such maps in this study a new attempt is tried to produce landslide susceptibility map of a part of west black sea region of turkey to obtain the fuzzy relations for producing the susceptibility map a landslide inventory database is compiled by both field surveys and airphoto studies a total of 266 landslides are identified in the study area and dominant mode of failure is rotational slide while the other mode of failures are soil flow and shallow translational slide the landslide inventory and the parameter maps are analyzed together using a computer program fullsa developed in this study the computer program utilizes the fuzzy relations and produces the landslide susceptibility map automatically according to this map 9 6 of the study area is classified as very high susceptibility 10 3 as high susceptibility 8 9 as moderate susceptibility 27 5 as low susceptibility and 43 8 as very low susceptibility or nonsusceptible areas the prediction performance of the susceptibility map is checked by considering actual landslides in the study area for this purpose strength of the relation rij and the root mean square error rmse values are calculated as 0 867 and 0 284 respectively these values show that the produced landslide susceptibility map in the present study has a sufficient reliability it is believed that the approach employed in this study mainly prevents the subjectivity sourced from the parameter selection and provides a support to improve the landslide susceptibility mapping studies

geo acoustic modelling of late and postglacial sedimentary units in the baltic sea and their acoustic visibility abstract acoustic profiling methods are commonly used in the geosciences to obtain knowledge about the sedimentary structures of marine deposits however their interpretation and the correlation of acoustic reflectors with sedimentological boundaries remain difficult the gradient in acoustic impedance determines the intensity of acoustic reflectors which are not necessarily sedimentary boundaries suitable geo acoustic models that cover a wide range of sediment types have not yet been developed for the baltic sea based on comprehensive investigations of sediment cores from mecklenburg bay and the arkona basin we developed geo acoustic models that enable the transfer of laboratory p wave velocity measurements to in situ conditions while considering changes in pressure salinity temperature and the frequency dependence of the p wave velocity i e acoustic dispersion this modelling allows the calculation of the wet bulk density and in situ p wave velocity from which the acoustic impedance is calculated from core logging and selected sedimentological data such as the water content loss on ignition and grain size precise plotting of core data into the acoustic profiles is now possible and represents a crucial step towards the interpretation of these profiles modelled p wave velocities are used to convert two way travel time to depth the average sedimentological parameters for the different development phases of the baltic sea are calculated using geo statistical methods and may allow for rough p wave estimations if core logging data are not available

landslide susceptibility mapping by neuro fuzzy approach in a landslide prone area cameron highlands malaysia this paper presents the results of the neuro fuzzy model using remote sensing data and geographic information system for landslide susceptibility analysis in a part of the cameron highlands areas in malaysia landslide locations in the study area were identified by interpreting aerial photographs and satellite images supported by extensive field surveys landsat tm satellite imagery was used to map the vegetation index maps of the topography lineaments normalized difference vegetation index ndvi and land cover were constructed from the spatial data sets eight landslide conditioning factors such as altitude slope gradient curvature distance from the drainage distance from the road lithology distance from the faults and ndvi were extracted from the spatial database these factors were analyzed using a neuro fuzzy model adaptive neuro fuzzy inference system to produce the landslide susceptibility maps during the model development works a total of five landslide susceptibility models were constructed for verification the results of the analyses were then compared with the field verified landslide locations additionally the receiver operating characteristic curves for all landslide susceptibility models were drawn and the area under curve values were calculated landslide locations were used to validate the results of the landslide susceptibility map and the verification results showed a 97 accuracy for model 5 employing all parameters produced in the present study as the landslide conditioning factors the validation results showed a sufficient agreement between the obtained susceptibility map and the existing data on the landslide areas qualitatively the model yields reasonable results which can be used for preliminary land use planning purposes

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

mid pleistocene lavas from the seguam volcanic center central aleutian arc closed system fractional crystallization of a basalt to rhyodacite eruptive suite in contrast to adjacent volcanic centers of the modern central aleutian arc seguam island developed on strongly extended arc crust k ar dates indicate that mid pleistocene late pleistocene and holocene eruptive phases constitute seguam this study focuses on the petrology of the mid pleistocene 1 07 07 ma turf point formation tpf which is dominated by an unusual suite of porphyritic basalt and basaltic andesite lavas with subordinate phenocryst poor andesite to rhyodacite lavas increasing whole rock feo mgo from basalt to dacite the anhydrous plag ol cpx opx mt phenocryst assemblage groundmass pigeonite and the reaction ol liq opx preserved in the mafic lavas indicate a tholeiitic affinity thermometry and comparison to published phase equilibria suggests that most tpf basalts crystallized plag ol cpx mt at 1160 c between about 3 5 kb 1 2 h2o andesites crystallized plag cpx opx mt at 1000 c between 3 4 kb with 3 5 h2o and dacites crystallized plag cpx opx mt at 1000 c between 1 2 kb with 2 3 h2o all lavas crystallized at f o 2 close to the nno buffer mineral compositions and textures indicate equilibrium crystallization of the evolved lavas petrographic evidence of open system mixing or assimilation is rare mgo cao al2o3 cr ni and sr abundances decrease and k2o na2o rb ba zr and pb increase with increasing sio2 50 71 lree enrichment ce yb n 1 7 0 2 characterizes most tpf lavas total ree contents increase and eu anomalies become more negative with increasing sio2 relative to other aleutian volcanic centers tpf basalts and basaltic andesites have lower k2o na2o tio2 rb ba sr zr y and lree abundances 87sr 86sr ratios 0 70361 0 70375 and ratios of 206pb 204pb 18 88 18 97 207pb 204pb 15 58 15 62 208pb 204pb 38 46 38 55 are the highest measured for any suite of lavas in the oceanic portion of the aleutian arc conversely end values 5 8 to 6 7 are among the lowest from the aleutians sr nd and pb ratios are virtually constant from basalt through rhyodacite whereas detectable isotopic heterogenity is observed at most other aleutian volcanic centers major and trace element ree and sr nd and pb isotopic compositions are consistent with the basaltic andesitic andesitic dacitic and rhyodacitic liquids evolving from tpf basaltic magma via closed system fractional crystallization alone fractionation models suggest that removal of 80 wt cumulate 61 plag 17 cpx 12 opx 7 ol and 3 mt can produce 20 wt rhyodacitic residual liquid per unit mass of parental basaltic liquid petrologic and physical constraints favor segregation of small batches of basalt from a larger mid crustal reservoir trapped below a low density upper crustal lid in these small magma batches the degree of cooling crystallization and fractionation are functions of the initial mass of basaltic magma segregated the thermal state of the upper crust and the magnitude of extension tholeiitic magmas erupted at seguam evolved by substantially different mechanisms than did calc alkaline lavas erupted at the adjacent volcanic centers of kanaga and adak on unextended arc crust these variable differentiation mechanisms and liquid lines of descent reflect contrasting thermal and mechanical conditions imposed by the different tectonic environments in which these centers grew at seguam intra arc extension promoted eruption of voluminous basalt and its differentiates unmodified by interaction with lower crustal or upper mantle wallrocks

statistical analysis of landslide susceptibility at yongin korea the aim of this study is to evaluate the susceptibility of landslides at yongin korea using a geographic information system gis landslide locations were identified in the yongin area from interpretation of aerial photographs field surveys and maps of the topography soil type timber cover and geology these data were collected and constructed into a spatial database using gis the factors that influence landslide occurrence such as slope aspect and curvature of topography were calculated from the topographic database texture material drainage and effective soil thickness were extracted from the soil database and type age diameter and density of timber were extracted from the forest database lithology was extracted from the geological database and land use was classified from the landsat tm satellite image landslide susceptibility was analyzed using the landslide occurrence factors by probability and logistic regression methods the results of the analysis were verified using the landslide location data the validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide location the gis was used to analyze the vast amount of data efficiently and statistical programs were used to maintain specificity and accuracy the results can be used to reduce associated hazards and to plan land use and construction

composition and structure of the central aleutian island arc from arc parallel wide angle seismic data new results from wide angle seismic data collected parallel to the central aleutian island arc require an intermediate to mafic composition for the middle crust and a mafic to ultramafic composition for the lower crust and yield lateral velocity variations that correspond to arc segmentation and trends in major element geochemistry the 3 d ray tracing 2 5 d inversion of this sparse wide angle data set which incorporates independent phase interpretations and new constraints on shallow velocity structure produces a faster and smoother result than a previously published velocity model middle crustal velocities of 6 5 7 3 km s over depths of 10 20 km indicate an andesitic to basaltic composition high lower crustal velocities of 7 3 7 7 km s over depths of 20 35 km are interpreted as ultramafic mafic cumulates and or garnet granulites the total crustal thickness is 35 37 km this result indicates that the aleutian island arc has higher velocities and thus more mafic compositions than average continental crust implying that significant modifications would be required for this arc to be a suitable building block for continental crust lateral variations in average crustal velocity below 10 km roughly correspond to trends in major element geochemistry of primitive mg 0 6 lavas the highest lower crustal velocities and presumably most mafic material are detected in the center of an arc segment between unmak and unalaska islands implying that arc segmentation exerts control over crustal composition

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

constraints on the composition of the aleutian arc lower crust from vp vs 1 determining the bulk composition of island arc lower crust is essential for distinguishing between competing models for arc magmatism and assessing the stability of arc lower crust we present new constraints on the composition of high p wave velocity vp 7 3 7 6 km s lower crust of the aleutian arc from best fitting average lower crustal vp vs ratio using sparse converted s waves from an along arc refraction profile we find a low vp vs of 1 7 1 75 using petrologic modeling we show that no single composition is likely to explain the combination of high vp and low vp vs our preferred explanation is a combination of clinopyroxenite 50 70 and alpha quartz bearing gabbros 30 50 this is consistent with aleutian xenoliths and lower crustal rocks in obducted arcs and implies that 30 40 of the full aleutian crust comprises ultramafic cumulates these results also suggest that small amounts of quartz can exert a strong influence on vp vs in arc crust

debris flow susceptibility mapping using frequency ratio and seed cells in a portion of a mountain international route dry central andes of argentina abstract debris flow and floods represent one of the main natural hazards that impact transport infrastructure causing serious damage economic losses and hinder regional economic development these processes are eventually associated with massive traffic cuts and direct damage to road structures to enable the prevention of such consequences this paper employs statistical modeling techniques various instability factors and geomorphological mapping to generate debris flow susceptibility maps in a portion of an important route on the dry andes of san juan in the agua negra river basin argentina a debris flows inventory map was prepared using satellite images and field checks the debris flows inventory was randomly divided into a model dataset 80 47 debris flows and remaining 20 12 debris flows data was used for validation purpose the instability factors chosen that influence debris flows occurrence were elevation slope angle slope aspect solar radiation topographic wetness index stream power index topographic position index melton ruggedness number terrain ruggedness index sediment transport capacity index plan curvature profile curvature lithology distance to road and proximity to stream using these factors six different models of debris flow susceptibility were calculated by frequency ratio fr lithology igneous complex was found to be important debris flows related factor in the study area the precision of the results was evaluated by receiver operating characteristic roc analysis according to the area under the curve auc the models of all flow track and natural breaks and all flow track and geometrical interval were 0 83 and 0 84 respectively showing a practically identical predictive capacity

gis based assessment of risk due to salt mining activities at tuzla bosnia and herzegovina ground subsidence triggered by salt mining from deposits located beneath the city of tuzla bosnia and herzegovina is one of the major dangers acting on a very densely urbanized area since 1950 when the salt deposit exploitation by means of boreholes began as demonstrated in this paper subsidence induced several hazard factors such as severe ground deformations the arising of deep and superficial fractures and a very fast water table rise connected with the brine extraction now affecting several districts the above mentioned factors have been quantified by the use of geomatic methodologies including field surveys and analysis of geographical data in order to estimate the historical sinking rates authors processed the large and never before processed amount of topographical data collected during two periods from 1956 to 1991 and from 1992 to 2003 with only poor data collected afterward traditional surveys were completely and definitively stopped the analysis reveals a cumulative subsidence as high as 12 m during the whole period causing damage to buildings and infrastructures within an area that includes a large portion of the historical town at present almost entirely destroyed modern sinking rates have been monitored with static gps whereas the presence of superficial fractures monitored with kinematic gps factors related to the presence of deep fractures and water table rise have been evaluated by curvature analysis techniques and piezometric data respectively finally hazard factors have been combined in a risk map using the gis geographical information system map algebra capabilities and a simple multicriteria decision analysis mda in order to do that a vulnerability map has been derived on the basis of information reported on a couple of recently sensed high resolution satellite imageries the final risk arisen from the combination of single hazard factors and vulnerability map highlights critical scenarios and unsuspected threatening that are under consideration by the local decision makers and urban planners in particular as highlighted in the final risk map the present day water table rise triggered by the decrease in brine pumping is seriously posing a threat to a portion of the city which is not the most involved in ground deformations

glacier fluctuations of jostedalsbreen western norway during the past 20 years the sensitive response of maritime mountain glaciers the steep outlet glaciers of jostedalsbreen western norway are good examples of sensitively reacting maritime mountain glaciers their changes in length frontal position and lower tongue s morphology during the past 20 years have been well documented at first they experienced a strong frontal advance after ad 2000 glacier behaviour was dominated by a strong frontal retreat in some cases causing a separation of the lowermost glacier tongue in this paper the glacier length changes are presented both visually and numerically supplemented by mass balance and meteorological data the glacier behaviour is interpreted and its causes are discussed whereas the factors controlling the advance during the 1990s seem clear the interpretation of the most recent retreat still leaves some uncertainties the actual glacier front behaviour cannot fully be related to the mass balance data terminus response times and relations between individual mass balance and meteorological parameters have changed some hypoth

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

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

landslide spatial susceptibility mapping by using gis and remote sensing techniques a case study in zigui county the three georges reservoir china landslides are one of the most destructive phenomena in nature and damage both property and lives every year in this paper a logistic regression model with datasets developed via a geographic information system and remotely sensed data was used to create a landslide spatial susceptibility map for the three gorges project reservoir region on the yangtze river in zigui county the five causative factors used in the logistic regression model were evaluated in different ways topographic slope and topographic aspect were derived from a topographical map at 1 50 000 scale bed rock slope relationship and lithology were obtained from a geological map at 1 50 000 scale and fractional vegetation cover fvc which represents the reduced frequency of landslides due to the vegetation canopy and ground cover and is also one of the most difficult parameters to estimate over broad geographic areas was generated using a back propagation neural network bpnn method based on cbers china brazil earth resources satellite data the results of which were compared with values measured in the field the obtained pearson correlation coefficient r was 0 899 then the fvc factor and the other four factors were used as the input to a logistic regression model by integrating the five factor maps in the geographical information system gis via pixel based computing the landslide spatial susceptibility map was obtained the study area was reclassified into four categories of landslide susceptibility severe moderate low and very low approximately 15 0 of the study area was identified as severe susceptibility and very low low and moderate susceptibility zones covered 21 8 41 7 and 21 5 of the area respectively these results have an accuracy of 78 90 thus by using a logistic regression model in a gis environment a spatial susceptibility map of landslides can be obtained and the regions in zigui county that are susceptible to landslides and need immediate protective and mitigation measures can be identified

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

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

spatial analysis of factors controlling the presence of closed depressions and gullies under forest application of rare event logistic regression abstract although numerous studies have reported on past geomorphic change it is a common difficulty to identify the relative role of driving human or climatic forces to that end the possibilities of rare events logistic regression are explored in a 1300 hectare large ancient forest in central belgium here 43 permanent gullies and 71 closed depressions were observed that were probably caused by an anthropogenically induced land use change in the past this human origin was confirmed for a limited number of case study areas by recent geomorphic research with dating and soil profile analysis the objective of this study is to analyze the factors controlling the position of all gullies and closed depressions in the study area and investigate their mutual relation this will indicate whether or not the results obtained for the small case study areas can be extrapolated to the rest of the geomorphic features found in the whole study area the obtained logistic regression models show that both anthropogenic and physical factors are important in the spatial distribution of both geomorphic features for the prediction of the occurrence of closed depressions anthropogenic factors are most important however the probability of finding a depression is larger close to reported prehistoric and roman archaeological sites on well developed undisturbed luvisols and on northeast to southeast facing slopes the local slope gradient of the soil surface is the most important factor in the multivariate model for predicting the presence of the permanent gullies the occurrence probability of permanent gullies is also larger on northeast to southeast facing slopes the anthropogenic factor expressed by the distance to the closed depressions is significant as a univariate model this suggests that a critical slope gradient is a prerequisite for gully incision but gully formation still needs to be triggered by a human induced land use change it can therefore be concluded that both the gullies and the closed depressions in the meerdaal forest are related to past human activity either directly through mining of loess or indirectly through runoff production on cropland this study also showed the potential of rare events logistic regression for analyzing the spatial pattern of geomorphological features in relation to environmental factors

early holocene history of the baltic sea as reflected in coastal sediments in blekinge southeastern sweden integrated palaeoecological studies of two fiord sediment sequences in the province of blekinge se sweden covering the time span 11 000 5000 cal bp reveal the timing and the environment for the ancylus lake littorina sea transition 9800 8500 cal bp the first ingression of saline water into the baltic sea through the danish straits occurred earlier than formerly assumed new evidence particularly mineral magnetic and palaeobotanical analyses demonstrate that on the general trend of the eustatically caused littorina transgression several minor fluctuations of the water level can be identified between 8500 and 5000 cal years bp a distinct regression phase around 8 100 cal bp is correlated with the greenland ice core cold event dated to 8200 ice core years bp this is described as a regional climatic catastrophe for the baltic sea region the coastal stratigraphy is compared with the offshore stratigraphy earlier studied a tentative shore displacement curve for early and middle holocene is presented

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

a spatiotemporal probabilistic modelling of storm induced shallow landsliding using aerial photographs and logistic regression landslides constitute one of the major natural hazards that could cause significant losses of life and property mapping or delineating areas prone to landsliding is therefore essential for land use activities and management decision making in hilly or mountainous regions a landslide hazard map can be constructed by a qualitative combination of maps of site conditions including geology topography and geomorphology by statistical methods through correlating landslide occurrence with geologic and geomorphic factors or by using safety factors from stability analysis a landslide hazard map should provide information on both the spatial and temporal probabilities of landsliding in a certain area however most previous studies have focused on susceptibility mapping rather than on hazard mapping in a spatiotemporal context this study aims at developing a predictive model based on both quasi static and dynamic variables to determine the probability of landsliding in terms of space and time the study area selected is about 13 km 2 in north lantau hong kong the source areas of the landslides caused by the rainstorms of 18 july 1992 and 4 5 november 1993 were interpreted from multi temporal aerial photographs landslide data lithology digital elevation model data land cover and rainfall data were digitized into a geographic information system database a logistic regression model was developed using lithology slope gradient slope aspect elevation slope shape land cover and rolling 24 it rainfall as independent variables since the dependent variable could be expressed in a dichotomous way this model achieved an overall accuracy of 87 2 with 89 5 of landslide grid cells correctly classified and found to be performing satisfactorily the model was then applied to rainfalls of a variety of periods of return to predict the probability of landsliding on natural slopes in space and time it is observed that the modelling techniques described here are useful for predicting the spatiotemporal probability of landsliding and can be used by land use planners to develop effective management strategies copyright 0 2003 john wiley sons ltd

experiments on vertical basement fault reactivation below volcanoes scaled modeling has been conducted to study the role played by the reactivation of vertical basement faults in the destabilization process of overlying volcanoes results show that basement fault reactivation induces the formation of faults within the volcanic edifice these faults delimite a central block which is extruded from between the two undeformed lateral parts of the edifice collapse of this central block can occur when heterogeneous cones are used in experiments revealing that mechanical interfaces are of paramount importance in triggering rockslide avalanches collapse structures may display horseshoe shapes in map view and are then surprisingly similar to avalanche scars resulting from failure created by magmatic intrusions in natural volcanoes large scale destabilisation of half the surface of the cone may also occur in a single event depending on the position of the reactivated basement fault below the edifice it is emphasized that the process under consideration may occur on a dormant volcano as well provided that a fault is reactivated below it

modeling landslide susceptibility in data scarce environments using optimized data mining and statistical methods abstract this study evaluated the generalizability of five models to select a suitable approach for landslide susceptibility modeling in data scarce environments in total 418 landslide inventories and 18 landslide conditioning factors were analyzed multicollinearity and factor optimization were investigated before data modeling and two experiments were then conducted in each experiment five susceptibility maps were produced based on support vector machine svm random forest rf weight of evidence woe ridge regression rid r and robust regression rr models the highest accuracy auc 0 85 was achieved with the svm model when either the full or limited landslide inventories were used furthermore the rf and woe models were severely affected when less landslide samples were used for training the other models were affected slightly when the training samples were limited

landslide susceptibility mapping using geological data a dem from aster images and an artificial neural network ann an efficient and accurate method of generating landslide susceptibility maps is very important to mitigate the loss of properties and lives caused by this type of geological hazard this study focuses on the development of an accurate and efficient method of data integration processing and generation of a landslide susceptibility map using an ann and data from aster images the method contains two major phases the first phase is the data integration and analysis and the second is the artificial neural network training and mapping the data integration and analysis phase involve gis based statistical analysis relating landslide occurrence to geological and dem digital elevation model derived geomorphological parameters the parameters include slope aspect elevation geology density of geological boundaries and distance to the boundaries this phase determines the geological and geomorphological factors that are significantly correlated with landslide occurrence the second phase further relates the landslide susceptibility index to the important geological and geomorphological parameters identified in the first phase through ann training the trained ann is then used to generate a landslide susceptibility map landslide data from the 2004 niigata earthquake and a dem derived from aster images were used the area provided enough landslide data to check the efficiency and accuracy of the developed method based on the initial results of the experiment the developed method is more than 90 accurate in determining the probability of landslide occurrence in a particular area

comparison of landslide susceptibility based on a decision tree model and actual landslide occurrence the akaishi mountains japan abstract this paper proposes a statistical decision tree model to analyze landslide susceptibility in a wide area of the akaishi mountains japan the objectives of this study were to validate the decision tree model by comparing landslide susceptibility and actual landslide occurrence and to reveal the relationships among landslide occurrence topography and geology landslide susceptibility was examined through ensemble learning with a decision tree decision trees are advantageous in that estimation processes and order of important explanatory variables are explicitly represented by the tree structures topographic characteristics elevation slope angle profile curvature plan curvature and dissection and undissection height and geological data were used as the explanatory variables these topographic characteristics were calculated from digital elevation models dems the objective variables were landslide occurrence and reactivation data between 1992 and 2002 that were depicted by satellite image analysis landslide susceptibility was validated by comparing actual data on landslides that occurred and reactivated after the model was constructed between 2002 and 2004 this study revealed that from 2002 to 2004 landslides tended to occur and reactivate in catchments with high landslide susceptibility the landslide susceptibility map thus depicts the actual landslide occurrence and reactivation in the akaishi mountains this result indicates that the decision tree model has appropriate accuracy for estimating the probabilities of future landslides the tree structure indicates that landslides occurred and reactivated frequently in the catchments that had an average slope angle exceeding ca 29 and a mode of slope angle exceeding 33 which agree well with previous studies a decision tree also quantitatively expresses important explanatory variables at the higher order of the tree structure

intra arc sedimentation in a low lying marginal arc eocene clarno formation central oregon abstract the clarno formation consists of andesitic volcaniclastic rocks interstratified with clayey paludal sediments and lava flows and cut locally by irregular hypabyssal stocks dikes and sills lateral lithofacies variations are pronounced and intrusive and extrusive volcanic rocks appear haphazardly emplaced throughout the formation a range of sedimentary environments is represented in the volcaniclastic sequences including near vent flow and breccia accumulations bouldery high gradient braided streams and relatively low gradient sandy tuff braidplains associated with paludal deposits we infer that the coarse grained volcaniclastic rocks of the clarno formation accumulated largely in volcanic flank and apron settings the formation s stratigraphy reflects an abundance of small volcanoes erupting into sedimentary lowlands and only a few scattered remnants of large central vent volcanoes are known the absence of systematic variation across a large outcrop belt argues against derivation of the succession from a line of volcanoes beyond the reaches of the present outcrop we infer that the arc was composed of small to medium size volcanoes arranged haphazardly across a broad area the sedimentary succession most probably accumulated in a series of intra arc depressions formed by diffuse block rotation driven by oblique subduction during the eocene

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