on the spatial relationship between landslides and causative factors on lantau island hong kong abstract this paper presents a statistical approach to study the spatial relationship between landslides and their causative factors at the regional level the approach is based on digital databases and incorporates such methods as statistics spatial pattern analysis and interactive mapping firstly the authors propose an object oriented conceptual model for describing a landslide event and a combined database of landslides and environmental factors is constructed by integrating the various databases within such a conceptual framework the statistical histogram spatial overlay and dynamic mapping methods are linked together to interactively evaluate the spatial pattern of the relationship between landslides and their causative factors a case study of an extreme event in 1993 on lantau island indicates that rainfall intensity and the migration of the center of the rainstorm greatly influence the occurrence of landslides on lantau island a regional difference in the relationship between landslides and topography is identified most of the landslides in the middle and western parts of the island occurred on slopes with slope angles of 25 35 while in the eastern part the corresponding range is 30 35 overlaying landslide data with land cover reveals that a large number of landslides occurred in the bareland and shrub covered area and in the transition zones between different vegetation types the proposed approach can be used not only to analyze the general characteristics of such a relationship but also to depict its spatial distribution and variation thereby providing a sound basis for regional landslide prediction

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

global magsat anomaly maps at ground level abstract four maps of the vertical component of the magnetic anomaly field are derived at ground level from magsat data at satellite altitude measurements performed below and above an altitude of 425 km are treated as two independent datasets by two different methods 1 a local downward continuation inverse method and 2 a global spherical harmonic decomposition for each map one and two dimensional energy density spectra are obtained and correlation coefficients are computed it is shown that anomalies with wavelengths as short as 700 km can be significantly recovered at ground level corresponding to a ground resolution of 350 km the improved correlation between anomalies and geodynamic features achieved with downward continued maps is illustrated with the example of southeast asia

intermediate wavelength magnetic anomalies over ocean basins we have examined three very long magnetic field profiles taken over ocean basins for the presence of intermediate wavelength magnetic anomalies one profile was from the atlantic ocean in the transatlantic geotraverse area one ran along latitude 35 sup 0 s in the se pacific and one ran along 150 sup 0 w in the pacific all three profiles show the presence of intermediate wavelength 65 1500 km magnetic anomalies generated in the crust or upper mantle the analysis of magnetic field power spectra shows that the core field becomes unimportant at about a wavelength of 1500 km sea floor spreading anomalies should produce a maximum in power at about a wavelength of 65 km between these two wavelengths there should be a minimum in power which is not seen on observed records inverting the anomalous field to obtain some idea of the magnetization necessary to explain these intermediate wavelength magnetic anomalies shows that values of magnetization in excess of 1 a m sup 1 are needed if the magnetized layer is as thick as the ocean crust alternatively rather large thicknesses of upper mantle material with lower intensities of magnetization need to be used the reason why such magnetization variations exist is not known itmore can be shown that upward continuation of the magnetic anomaly signature to an altitude of 350 km about the perihelion altitude of magsat will produce anomalies up to 10 nt in amplitude these should be capable of being seen by magsat and thus allow us to determine the spatial arrangement of the intermediate wavelength anomalies and hence hopefully a clue as to their origin less

estimating potential landslide sites of an upland sub watershed in western ghat s of kerala india through frequency ratio and gis the purpose of this study is to assess the susceptibility of landslides in parts of western ghats kerala india using a geographical information system gis landslide inventory of the area was made by detailed field surveys and the analysis of the topographical maps the landslide triggering factors are considered to be slope angle slope aspect slope curvature slope length distance from drainage distance from lineaments lithology land use and geomorphology arcgis version 8 3 was used to manipulate and analyse all the collected data probabilistic likelihood ratio was used to create a landslide susceptibility map for the study area the result was validated using the area under curve auc method and temporal data of landslide occurrences the validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide locations as the result the success rate of the model was 84 46 and the prediction rate of the model was 82 38 shows high prediction accuracy in the reclassified final landslide susceptibility zone map 5 68 of the total area is classified as critical in nature the landslide susceptibility map thus produced can be used to reduce hazards associated with landslides and to land cover planning

magnetization of lower crust and interpretation of regional magnetic anomalies example from lofoten and vesteralen norway the interpretation of regional magnetic anomalies commonly observed over continental crust in both satellite and near surface magnetic data has remained enigmatic in its requirement for laterally extensive thick highly magnetic and deep seated sources presented here are the results of a detailed field analytical and experimental study of the magnetic mineralogy and magnetic properties of rocks from lofoten and vesteralen norway a province of deep seated origin with associated regional magnetic and gravity anomalies these rocks have a bulk magnetic character of surprising uniformity with susceptibilities hysteresis and curie temperatures defined solely by coarse grained magnetite stable remanence is observed in samples from sw lofoten but is not of significant magnitude the thermal enhancement of magnetic susceptibility the hopkinson effect is not important rocks from the deepest part of the section have the largest average susceptibilities 6 10 2 si and magnitudes of natural remanent magnetization nrm 5 10 4 a m2 kg these values of susceptibility together with the oft observed viscous character of the nrm suggest that these granulite facies lithologies particularly those of sw lofoten are perfect examples of lower crustal sources of typical regional magnetic anomalies furthermore these intermediate pressure granulites define a unique magnetic petrology especially for mafic compositions at higher grades of metamorphism high pressure granulites and eclogites or lower grades greenschist and amphibolite facies such magnetite bearing assemblages will be unstable and their high or low grade equivalents will be only weakly magnetic this evidence and these conclusions may be used to constrain models of lower crustal sources of regional magnetic anomalies over stable cratons it portrays the lower crust as a highly magnetic unit defined by metamorphic grade with a curie isotherm of 575 c magnetite and magnetization parallel to the ambient geomagnetic field induced and viscous components

a comparison of the gis based landslide susceptibility assessment methods multivariate versus bivariate the purpose of this study is to evaluate and to compare the results of multivariate logical regression and bivariate landslide susceptibility methods in geographical information system gis based landslide susceptibility assessment procedures in order to achieve this goal the asarsuyu catchment in nw turkey was selected as a test zone because of its well known landslide occurrences interfering with the e 5 highway mountain pass

extraction of potential debris source areas by logistic regression technique a case study from barla besparmak and kapi mountains nw taurids turkey debris flow is one of the most destructive mass movements sometimes regional debris flow susceptibility or hazard assessments can be more difficult than the other mass movements determination of debris accumulation zones and debris source areas which is one of the most crucial stages in debris flow investigations can be too difficult because of morphological restrictions the main goal of the present study is to extract debris source areas by logistic regression analyses based on the data from the slopes of the barla besparmak and kapi mountains in the sw part of the taurids mountain belt of turkey where formation of debris material are clearly evident and common in this study in order to achieve this goal extensive field observations to identify the areal extent of debris source areas and debris material air photo studies to determine the debris source areas and also desk studies including geographical information system gis applications and statistical assessments were performed to justify the training data used in logistic regression analyses as representative a random sampling procedure was applied by using the results of the logistic regression analysis the debris source area probability map of the region is produced however according to the field experiences of the authors the produced map yielded over predicted results the main source of the over prediction is structural relation between the bedding planes and slope aspects on the basis of the field observations for the generation of debris the dip of the bedding planes must be taken into consideration regarding the slope face in order to eliminate this problem in this study an approach has been developed using probability distribution of the aspect values with the application of structural adjustment the final adjusted debris source area probability map is obtained for the study area the field observations revealed that the actual debris source areas in the field coincide with the areas having high probability values on this final map

wrenching in the external zone of the betic cordilleras southern spain abstract regional structural trends in the caravaca huescar area forming the central part of the external zone in the betic cordilleras indicate that deformation of the area results from right lateral wrenching subparallel to the paleogeographic zonation the structural trends do not fit the nappe interpretation generally used elsewhere in the external zone arguments for wrenching in the area are the structural inverse symmetry with respect to a central transcurrent fault zone the crevillente fault zone the distributional pattern of stratigraphic anomalies and types of deformation and the outcrop pattern of the paleogeographic zones it is argued that certain tectonic units in the area formerly interpreted as klippes in a nappe configuration form centers of flower structures and are vertically squeezed out blocks a theoretical model is sketched illustrating the evolution of a wrench zone under the stratigraphic conditions of the studied area and resulting in its present characteristics many of the features of the caravaca huescar area are also present elsewhere in the external zone and support the idea that wrenching was a major deformational mechanism it is therefore suggested that the external zone should in general not be described in terms of a nappe structure as has been done so far but in terms of a strike slip orogen or a wrenched continental margin

gis based landslide susceptibility mapping for a problematic segment of the natural gas pipeline hendek turkey a segment of natural gas pipeline was damaged due to landsliding near hendek re routing of the pipeline is planned but it requires the preparation of a landslide susceptibility map in this study the statistical index wi and weighting factor wf methods have been used with gis to prepare a landslide susceptibility map of the problematic segment of the pipeline for this purpose thematic layers including landslide inventory lithology slope aspect elevation land use land cover distance to stream and drainage density were used in the study area landslides occur in the unconsolidated to semi consolidated clayey unit and regolith the wf method gives better results than the wi method lithology is found to be the most important aspect in the study area based on the findings obtained in this study the unconsolidated to semi consolidated clayey unit and alluvium should be avoided during re routing agricultural activities should not be allowed in the close vicinity of the pipeline

landslide hazard zonation using remote sensing and gis a case study of dikrong river basin arunachal pradesh india landslides are among the most costly and damaging natural hazards in mountainous regions triggered mainly under the influence of earthquakes and or rainfall in the present study landslide hazard zonation lhz of dikrong river basin of arunachal pradesh was carried out using remote sensing and geographic information system gis various thematic layers namely slope photo lineament buffer thrust buffer relative relief map geology and land use land cover map were generated using remote sensing data and gis the weighting rating system based on the relative importance of various causative factors as derived from remotely sensed data and other thematic maps were used for the lhz the different classes of thematic layers were assigned the corresponding rating value as attribute information in the gis and an attribute map was generated for each data layer each class within a thematic layer was assigned an ordinal rating from 0 to 9 summation of these attribute maps were then multiplied by the corresponding weights to yield the landslide hazard index lhi for each cell using trial and error method the weight rating values have been re adjusted the lhi threshold values used were 142 165 189 and 216 a lhz map was prepared showing the five zones namely very low hazard low hazard moderate hazard high hazard and very high hazard by using the slicing operation

initial scalar magnetic anomaly map from magsat a scalar magnetic anomaly map between 50 geographic latitude was derived from magsat data acquired during the november 1979 to june 1980 mission lifetime separation of anomaly fields from core and external fields was accomplished utilizing techniques developed for pogo data mayhew 1979 langel et al 1980 comparison with a similar map from pogo data shows that the basic anomaly patterns are essentially reproducible except in a few regions such as the atlantic and pacific at latitudes south of 15 increased resolution due to a lower measurement altitude is evident in the magsat map

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

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

the application of predictive modeling techniques to landslides induced by earthquakes the case study of the 26 september 1997 umbria marche earthquake italy abstract during september and october 1997 an earthquake sequence of moderate magnitude struck the umbria and marche regions central italy as a consequence of the most severe shocks several landslides were triggered on bedrock calcareous debris and sandy clay deposits the landslide inventory collected in the field and by aerial photo interpretation provided an opportunity to test the accuracy of existing predictive relations for landslide hazard zoning and to formulate new ones shallow soil slides and debris slides were selected to verify the prediction performance of the methods which are based on a simplified model geotechnique 15 1965 139 that calculate landslide displacements during cyclic seismic loading rock falls were modeled using a different approach to produce an empirical predictive rule for determining the probability of detachment of blocks when landslides occur along pre existing or newly formed failure surfaces the arias intensity and destructiveness potential are the strong ground motion parameters that best relate to displacements the predictive relation proposed for rock falls evaluates the probability of occurrence as a function of the slope angle and the peak ground acceleration pga

numerical simulations of a gravity wave event over ccope part iii the role of a mountain plains solenoid in the generation of the second wave episode abstract mesoscale model simulations have been performed of the second episode of gravity waves observed in great detail in previous studies on 11 12 july 1981 during the cooperative convective precipitation experiment the dominant wave simulated by the model was mechanically forced by the strong updraft associated with a mountain plains solenoid mps as this updraft impinged upon a stratified shear layer above the deep well mixed boundary layer that developed due to strong sensible heating over the absaroka mountains the gravity wave was created this wave rapidly weakened as it propagated eastward however explosive convection developed directly over the remnant gravity wave as an eastward propagating density current produced by a rainband generated within the mps leeside convergence zone merged with a westward propagating density current in eastern montana the greatly strengthened cool pool resulting from this new convection then generated a bore wave that appeared to be continuous with the move

landslide susceptibility analysis and verification using the bayesian probability model the bayesian probability model using the weight of evidence method was applied to the task of evaluating landslide susceptibility using gis data the location chosen for the study was the janghung area in korea which suffered substantial landslide damage following heavy rain in 1998 using the location of the landslides as well as topographic factors such as soil forest and land use the weight of evidence method was used to calculate each factor s rating tests of conditional independence were performed for the selection of the factors allowing the large number of combinations of factors to be analyzed for each factor rating the contrast values w and w were overlaid for landslide susceptibility mapping the results of the analysis were verified using the observed landslide locations and among the combinations the slope aspect curvature soil material and wood types show the best results

gis modelling of slope stability in phewa tal watershed nepal abstract hazards are an inherent but dangerous and costly element of mountainous environments conventional maps of mountain hazards provide useful inventories of hazardous sites but provide little insight into the operation of the hazards furthermore this approach tends to rely heavily on subjective interpretation of the landscape which means that the results can not be replicated or transferred to other areas thus alternative approaches employing the quantitative capabilities of geographic information systems gis to model and predict slope stability are receiving increasing attention this paper reports on the use of a diverse gis database compiled primarily from existing maps and aerial photographs to construct a regional model of slope stability in phewa tal watershed nepal an integral part of the research was to explore an alternative approach to the commonly used grid cell approach by employing geomorphometrically significant terrain units the terrain units employed were created by generating line networks representing local maxima and minima extracted from elevation and curvature surfaces one of the chief benefits of applying gis technology in this research was the ability to georeference all of the attribute data to these terrain units in doing so it allowed the database to be exported into an external statistical package where the terrain units could be statistically explored as the basic analytical unit the application of a variety of statistical techniques resulted in logistic regression being selected as the most useful logistic regression successfully predicted terrain units as being either stable or unstable at a rate of approximately 90 concordance with a conventionally produced map of slope stability the statistical probabilities of terrain unit stability were imported back into the gis to produce a map of predicted slope stability that compared well with the conventional map of slope stability the findings of this research suggest that the use of geomorphometrically significant terrain units extracted from a digital elevation model dem are an efficient alternative to approaches using regular grid cells in particular the terrain units facilitated the use of logistic regression and significantly decreased the amount of computing costs finally this research also suggests that important information can be gathered from existing information sources such as maps aerial photographs and written documents thereby limiting the need for costly and time consuming field work at the reconnaissance level based on this latter finding other information sources such as satellite imagery should be examined

a gis based automated procedure for landslide susceptibility mapping by the conditional analysis method the baganza valley case study italian northern apennines among the many gis based multivariate statistical methods for landslide susceptibility zonation the so called conditional analysis method holds a special place for its conceptual simplicity in fact in this method landslide susceptibility is simply expressed as landslide density in correspondence with different combinations of instability factor classes to overcome the operational complexity connected to the long tedious and error prone sequence of commands required by the procedure a shell script mainly based on the grass gis was created the script starting from a landslide inventory map and a number of factor maps automatically carries out the whole procedure resulting in the construction of a map with five landslide susceptibility classes a validation procedure allows to assess the reliability of the resulting model while the simple mean deviation of the density values in the factor class combinations helps to evaluate the goodness of landslide density distribution the procedure was applied to a relatively small basin 167 km2 in the italian northern apennines considering three landslide types namely rotational slides flows and complex landslides for a total of 1 137 landslides and five factors namely lithology slope angle and aspect elevation and slope bedding relations the analysis of the resulting 31 different models obtained combining the five factors confirms the role of lithology slope angle and slope bedding relations in influencing slope stability

doline probability map using logistic regression and gis technology in the central ebro basin spain in the surroundings of zaragoza karstification processes are especially intense in covered karst areas where fluvial terraces lie directly on tertiary evaporites since the beginning of quaternary these processes have lead to the development of collapse and subsidence dolines with a wide range of sizes which have significant economic impacts to reduce economic impact and increase safety a regional analysis of this phenomenon is needed for spatial management therefore a probability map of dolines was developed using logistic regression and geographic information system gis techniques this paper covers the selection of input data manipulation of data using the gis technology and the use of logistic regression to generate a doline probability map the primary variable in the doline development in this area is geomorphology represented by the location of endorheic areas and different terrace levels secondary variables are the presence of irrigation and the water table gradient

neural network modeling for regional hazard assessment of debris flow in lake qionghai watershed china this paper presents a neural network nn based model to assess the regional hazard degree of debris flows in lake qionghai watershed china the nn model was used as an alternative for the more conventional linear model mfcam multi factor composite assessment model in order to effectively handle the nonlinearity and uncertainty inherent in the debris flow hazard analysis the nn model was configured using a three layer structure with eight input nodes and one output node and the number of nodes in the hidden layer was determined through an iterative process of varying the number of nodes in the hidden layer until an optimal performance was achieved the eight variables used to represent the eight input nodes include density of debris flow gully degree of weathering of rocks active fault density area percentage of slope land greater than 25 of the total land apl25 frequency of flooding hazards average covariance of monthly precipitation by 10 years acmp10 average days with rainfall 25 mm by 10 years 25d10y and percentage of cultivated land with slope land greater than 25 of the total cultivated land pcl25 the output node represents the hazard degree ranks hdr the model was trained with the 35 sets of data obtained from previous researches reported in literatures and an explicit uncertainty analysis was undertaken to address the uncertainty in model training and prediction before the nn model is extrapolated to lake qionghai watershed a validation case different from the above data is conducted in addition the performances of the nn model and the mfcam were compared the nn model predicted that the hdrs of the five sub watersheds in the lake qionghai watershed were iv iv iii iii and iv v indicating that the study area covers normal hazard and severe hazard areas based on the nn model results debris flow management and economic development strategies in the study are proposed for each sub watershed

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

magnetic measurements aboard a stratospheric balloon abstract we have measured the total intensity of the earth s magnetic field above the western mediterranean along a 2000 km profile flown at an altitude of 40 km a proton magnetometer was aboard a cnes centre national d etudes spatiales stratospheric balloon the core field and transient external field contributions have been carefully determined and removed from the data the resulting profile reveals significant anomalies of 10 20 nt amplitudes with 100 1200 km wavelengths these anomalies have a clear crustal origin and can be related to heterogeneities in magnetisation in the oceanic algero provencal basin and to major faults of the spanish continental crust comparison of our new data with previous data obtained over the same area at about 1 km altitude aeromagnetic surveys and about 400 km altitude magsat demonstrates the potential of stratospheric balloon measurements in bridging the 200 1500 km gap that exists in the knowledge of crustal anomalies a gap that is unavoidable if only aeromagnetic and satellite like magsat data are used

role of strike slip faults in the betic rifian orogeny abstract a new model for the betic rifian orogeny of the western mediterranean spain and north africa is proposed in which four strike slip faults play an important role the faults are not of the same age two faults the left lateral jebha fault to the south in morocco and principally in the mediterranean sea and the right lateral north betic fault southern spain to the north define the boundaries of the alboran block betic and rifian internal zones final movement along these faults was during the burdigalian time two other faults the left lateral nekor fault north africa to the south of the jebha fault and the right lateral crevillente fault somewhat to the north of the north betic fault define a larger alboran block including part of the betic and rifian external zones that was present during the tortonian the following sequence of events is proposed 1 a during the eocene and oligocene the african and european plates converged in a n s sense causing the breakup and overthrusting of the betic rifian and kabyle internal zones and then the movement towards the wsw of the alboran block by slip along the jebha and north betic faults 2 b by the end of burdigalian time movement along the jebha and north betic faults ceased 3 c with continued n s convergence the nekor and crevillente faults which bound a larger alboran block were formed during the mid and late miocene the arc of gibraltar the zone lying between the four major faults seems to be a result of wsw motion of a crustal block being thrust over external zones the model proposed adds to the earlier idea that tectogenesis proceeds from the interior to the exterior of an erogenic belt in the betic rifian orogeny major strike slip fracture zones shifted to the exterior of the orogenic belt as the orogeny progressed in order to relieve the stress caused by locking of the more internal faults

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

a back propagation network for the assessment of susceptibility to rock slope failure in the eastern portion of the southern cross island highway in taiwan an assessment of the susceptibility to rock slope failure by means of a back propagation network is proposed for the eastern portion of the southern cross island highway in taiwan the model was developed on the basis of six influence parameters of rock slope instability which include the rock type slope aspect slope angle joint set number joint spacing and bedding slope relationship the values of these influence parameters were used as inputs for the network and were classified as nominal scales in terms of binary numbers while the state of failure non failure of a given slope was assumed to be the output variable data on a total of 170 slopes along the highway was fed into the network for learning according to the outputs of the network the susceptibility to rock slope failure is categorized into four levels namely low medium low medium and high which are mapped along the highway three highly susceptible regions are found which can be viewed as hazardous sections requiring cautionary measures moreover the proposed model can be used as a tool for determining the possible state of an unfamiliar rock slope in the context of devising management strategies to be applied to the investigated portion of the highway

intermediate wavelength magnetic anomalies over the central pacific we have extracted the intermediate wavelength magnetic anomaly field from the marine survey data of the central pacific in the band pass of 4000 400 km spherical harmonic degree 10 100 our technique minimizes the effects of external field sources secular variation and strike aliasing the objective of this paper is to demonstrate this capability compare the derived sea surface field to the equivalent magsat data set and demonstrate that anomalies observed in both fields are correctable to geologic features within the oceanic lithosphere as expected the sea surface field exhibits a strong spatial correlation to and a better resolution than the magsat field however the magsat field also displays a diminished resolution for wavelengths less than 1900 km when compared to the upward continued sea surface data two reasons are likely for this diminished resolution 1 differences in the resolution of the spherical harmonic reference fields and 2 an increased noise level in the magsat data at the shorter wavelengths other sources of error are also considered we also demonstrate that the remanent magnetization of the central pacific seamounts produces negative magnetic anomalies which are observed at satellite altitude other sources including the thickened crust of the oceanic plateaus and regional petrologic variations can be associated with intermediate wavelength anomalies observed in both the magsat and the sea surface fields

seafloor spreading anomalies in the magsat field of the north atlantic we show that a simple magnetization model for the crust of the north atlantic basin will explain the major anomalies of the magsat intermediate wavelength magnetic field over the basin our seafloor spreading model incorporates anomalous skewness and enhanced magnetization near the spreading axis and at the cretaceous quiet zones the anomalies over the young oceanic crust indicate a decrease in susceptibility away from the spreading axis the enhanced magnetization over the cretaceous quiet zone could be due to an increased main field intensity or a change in the spreading center processes during the cretaceous though similar observations are not readily apparent for other basins the north atlantic correlation indicates that an investigation of the remanent magnetization of the ocean crust could provide a standard for the evaluation of the intermediate wavelength magnetic field the models presented in this paper demonstrate that a sizable percentage of the intermediate wavelength energy in the magsat field is derived from sources within the earth s crust it also demonstrates that remanent magnetization is an important source of the magsat field over oceanic areas we seek to demonstrate in this paper that although components of the main field are likely to contribute to the intermediate wavelength scalar field we can correlate the anomaly field over the north atlantic to the well studied thermal remanent magnetization of the oceanic crust with a minor component of induced magnetization associated with younger oceanic crust

a time space based approach for mapping rainfall induced shallow landslide hazard a rainfall induced shallow landslide is a major hazard in mountainous terrain but a time space based approach is still an unsettled issue for mapping rainfall induced shallow landslide hazards rain induces a rise of the groundwater level and an increase in pore water pressure that results in slope failures in this study an integrated infinite slope analysis model has been developed to evaluate the influence of infiltration on surficial stability of slopes by the limit equilibrium method based on this new integrated infinite slope analysis model a time space based approach has been implemented to map the distributed landslide hazard in a gis geographic information systems and to evaluate the shallow slope failure induced by a particular rainfall event that accounts for the rainfall intensity and duration the case study results in a comprehensive time space landslide hazard map that illustrates the change of the safety factor and the depth of the wetting front over time

landslide susceptibility mapping by correlation between topography and geological structure the janghung area korea the purpose of this study is to develop and apply the technique for landslide susceptibility analysis using geological structure in a geographic information system gis in the study area the janghung area of korea landslide locations were detected from indian remote sensing irs satellite images by change detection where the geological structure of foliation was surveyed and analysed the landslide occurrence factors location of landslide geological structure and topography were constructed into a spatial database then strike and dip of the foliation and the aspect and slope of the topography were compared and the results which were verified using landslide location data show that foliation of gneiss has a geometrical relation to the joint or fault that leads to a landslide using the geometrical relations the landslide susceptibility was assessed and verified the verification results showed satisfactory agreement between the susceptibility map and the landslide location data

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

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

discontinuity controlled probabilistic slope failure risk maps of the altindag settlement region in turkey the evaluation of potential rock slope problems using stereographic projection techniques known as kinematic analysis is one of the most important parts of a slope stability investigation to be carried out in jointed rock media in conventional stereoprojection techniques for the assessment of possible rock slope failures the peak orientations of joints together with the slope geometry and the friction angle of the weakness planes are used other possible joint orientations which may be encountered in the rock media are ignored although they belong to the group of joint peak orientations in this study nearly vertical jointed andesites cropped out at the altindag settlement region in ankara were studied in order to evaluate the relevance of this ignored discontinuity orientation data on slope stability as a result probabilistic risk maps for planar toppling and wedge failures were produced using the kinematic rules and digital elevation model of the study area the comparison of the distribution of the actual failures in the area and the probabilistic risk maps prepared for the study area revealed that all of the identified failures are found to be located in the higher risk zones on the probabilistic risk maps

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