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1.
Many landslides occur every year during heavy rains at the Hai Van Pass and surrounding area in central Vietnam, where granitic rocks are distributed. As is common in granite areas, these landslides often occur as small-scale flow-type and slump-type landslides. However, several horseshoe-shaped loose slopes of widths and lengths of 500 to 800 m, which incorporate these landslides, are observed on slopes across the area. These topographies resemble those formed by past and present large-scale landslides. The presence of such a topography and the repeated occurrences of landslides within this topography are rare in granite areas, where shallow flow-type landslides are generally frequent. To understand the mechanism causing the landslides in the Hai Van region, and as a support for future risk assessment, the factors and processes leading to the formation of such a topography and their relationship with these landslides must be identified and assessed. This study investigated the history of past landslide movement in the Hai Van Pass and surrounding area through observations of drill cores and outcrops, and analysis of the direction of remanent magnetism in the granitic rocks. Mineral compositions, cracks, degrees of weathering, and topographic shapes of the granitic rocks and their relationship to the landslides occurring today were also investigated. The results of the study reveal no variation in the direction of remanent magnetism in the granitic rocks in the region that would indicate disturbance of the ground due to a past large-scale landslide. No evidence of such an event could also be found both in the drill cores and the rock outcrops. Further, results of the analysis of cracks and weathering pattern confirm that the topography of the region is affected by the weathering of the granitic rocks that progresses in concentric circles of various sizes. Thus, it can be concluded that these topographies were not formed by a singular large-scale landslide of the past, but rather by a composite of relatively shallow landslides occurring on the slope of dome structures unique to granite areas, which are formed by differential weathering and denudation regulated by cracks.  相似文献   

2.
This paper proposes a methodology aimed at reconstructing the maximum thickness mobilized by shallow landslides in fine-grained soils with the aid of geological and geotechnical analyses. The methodology, implemented within a geographic information system (GIS) environment, is composed of two stages for map reconstruction and two stages for map validation. The first stage of map reconstruction is aimed at individuating the soil thickness on the basis of only topographical and geological analyses; the second stage improves the previously obtained map with the aid of morphological and geotechnical analyses that provide a thickness map usable for shallow landslide susceptibility assessment. This map is validated with the aid of both in situ investigations (stage I), and geotechnical models able to back-analyse shallow precipitation-induced landslides over a wide area (stage II). An application of the proposed methodology is provided for a test area of the Calabria region (southern Italy) that is representative of the Catanzaro Strait, where widely diffused shallow landslides in fine-grained soils systematically occur. The results highlight the usefulness and reliability of the geotechnical models when implemented with the aid of a database representative of fine-grained soils while a secondary role is played by in situ investigations that in the test site have been performed only in a few representative and accessible areas.  相似文献   

3.
The present study was conducted along the Mugling–Narayanghat road section and its surrounding region that is most affected by landslide and related mass-movement phenomena. The main rock types in the study area are limestone, dolomite, slate, phyllite, quartzite and amphibolites of Lesser Himalaya, sandstone, mudstone and conglomerates of Siwaliks and Holocene Deposits. Due to the important role of geology and rock weathering in the instabilities, an attempt has been made to understand the relationship between these phenomena. Consequently, landslides of the road section and its surrounding region have been assessed using remote sensing, Geographical information systems and multiple field visits. A landslide inventory map was prepared and comprising 275 landslides. Nine landslides representing the whole area were selected for detailed studies. Field surveys, integrated with laboratory tests, were used as the main criteria for determining the weathering zones in the landslide area. From the overall study, it is seen that large and complex landslides are related to deep rock weathering followed by the intervention of geological structures as faults, joints and fractures. Rotational types of landslides are observed in highly weathered rocks, where the dip direction of the foliation plane together with the rock weathering plays a principle role. Shallow landslides are developed in the slope covered by residual soil or colluviums. The rock is rather fresh below these covers. Some shallow landslides (rock topples) are related to the attitude of the foliation plane and are generally observed in fresh rocks. Debris slides and debris flows occur in colluviums or residual soil-covered slopes. In few instances, they are also related to the rock fall occurring at higher slopes. The materials from the rock fall are mixed with the colluviums and other materials lying on the slope downhill and flow as debris flow. Rock falls are mainly related to the joint pattern and the slope angle. They are found in less-weathered rocks. From all these, it is concluded that the rock weathering followed by geological structures has prominent role in the rock slope instability along Mugling–Narayanghat road section and its surrounding regions.  相似文献   

4.
This paper presents the results of geographical information system (GIS)-based landslide susceptibility mapping in Ayvalık, western Turkey using multi-criteria decision analysis. The methodology followed in the study includes data production, standardization, and analysis stages. A landslide inventory of the study area was compiled from aerial photographs, satellite image interpretations, and detailed field surveys. In total, 45 landslides were recorded and mapped. The areal extent of the landslides is 1.75 km2. The identified landslides are mostly shallow-seated, and generally exhibit progressive character. They are mainly classified as rotational, planar, and toppling failures. In all, 51, 45, and 4% of the landslides mapped are rotational, planar, and toppling types, respectively. Morphological, geological, and land-use data were produced using existing topographical and relevant thematic maps in a GIS framework. The considered landslide-conditioning parameters were slope gradient, slope aspect, lithology, weathering state of the rocks, stream power index, topographical wetness index, distance from drainage, lineament density, and land-cover and vegetation density. These landslide parameters were standardized in a common data scale by fuzzy membership functions. Then, the degree to which each parameter contributed to landslides was determined using the analytical hierarchy process method, and the weight values of these parameters were calculated. The weight values obtained were assigned to the corresponding parameters, and then the weighted parameters were combined to produce a landslide susceptibility map. The results obtained from the susceptibility map were evaluated with the landslide location data to assess the reliability of the map. Based on the findings obtained in this study, it was found that 5.19% of the total area was prone to landsliding due to the existence of highly and completely weathered lithologic units and due to the adverse effects of topography and improper land use.  相似文献   

5.
香港花岗岩风化分级化学指标体系与风化壳分带   总被引：10，自引：3，他引：7  
火成岩的化学风化过程实质上就是碱、碱土金属组分水解淋失与脱硅富铁铝化的地球化学过程。不同风化程度的岩石处于整个化学风化过程的不同阶段,因而具有不同的化学成分和风化度指标。笔者在对香港九龙两个地方5个钻孔共计150件不同深度、不同风化程度的样品化学全分析结果与岩土风化程度宏观判别结果的相互对比、选择和确认的基础上,建立了香港地区花岗岩风化岩土风化程度工程分级的化学指标体系。这一研究成果的提出不仅有利于提高花岗岩风化岩土工程分类的科。学性、可靠性和实用性,而且可以为风化岩土工程特性与风化作用关系研究提供理论依据。  相似文献   

6.
This work focuses on developing multidisciplinary researches concerning weathering profiles related to landscape evolution of the Capo Vaticano promontory on the Calabria Tyrrhenian side (southern Italy). In this area, the tectonic uplift, occurred at least since Pleistocene, together with the Mediterranean climatic conditions, is the main cause of deep weathering and denudation processes. The latter occurred on the outcropping rocks of the crystalline-metamorphic basement, made up of weathered granitoids, in turn belonging to the Monte Poro granitoid complex (intermediate to felsic plutonic rocks covered by Cenozoic sedimentary successions). Field observations coupled to borehole explorations, geophysical surveys, and minero-petrographical analyses allowed the characterization of the granitoid outcrops typical of the studied area in terms of kind and degree of slope instability. This characterization was based on suitable correlations verified between several factors as weathering degree, elastic properties of rocks, and discontinuity features. Weathering profiles are mainly composed by rock masses varying from completely weathered rock with corestones of highly weathered rock (classes IV–V) to slightly weathered rocks (class II). The weathered rocks are involved in several landslide typologies such as debris flow (frequency 48.5%), translational slide (frequency 33.3%), and minor rock fall and rotational slide (frequency 9%). The achieved data allowed the establishment of a general correlation between weathering degree and type of slope instability. Debris flow-type instabilities are predominant on the steeper slopes, involving very poor rock masses ascribed to the shallowest portions of the weathering class IV. Translational slides are less widespread than the previous ones and often involve a mixture of soil and highly weathered rocks. Rotational slides are more frequently close to the top of the slopes, where the thicknesses of more weathered rocks increase, and involve mainly rock masses belonging to the weathering classes IV and V. Rock falls mostly occur on the vertical escarpments of the road cuts and are controlled by the characteristics of the main discontinuities. The assessment of rock mass rating and slope mass rating, based on the application of the discontinuity data, allowed respectively an evaluation of the quality of rock masses and of the susceptibility of rock slopes to failure. The comparison between the last one and the real stability conditions along the cut slopes shows a good correspondence. Finally, the geological strength index system was also applied for the estimation of rock mass properties. The achieved results give a worthy support for a better understanding of the relationship between the distribution of landslides and the geological features related to different weathering degrees. Therefore, they can provide a reliable tool to evaluate the potential stability conditions of the rock slopes in the studied area and a general reference framework for the study of weathering processes in other regions with similar geological features.  相似文献   

7.
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8.
Shallow landslides are a prevalent concern in mountainous or hilly regions that can result in severe societal, economic, and environmental impacts. The challenge is further compounded as the size and location of a potential slide is often unknown. This study presents a generalized approach for the evaluation of regional shallow landslide susceptibility using an existing shallow landslide inventory, remote sensing data, and various geotechnical scenarios. The three-dimensional limit equilibrium model derived in this study uses a raster-based approach that uniquely integrates tree root reinforcement, earth pressure boundary forces, and pseudo-static seismic accelerations. Contributions of this methodology include the back-calculation of soil strength from a landslide inventory, sensitivity analyses regarding landslide size-pixel size relationships, and the determination of shallow landslide susceptibility for a landscape or infrastructure considering various root, water, and seismic conditions using lidar bare-earth DEMs as a topographic input. Using a distribution of inventoried landslide points and random points in non-landslide locales, the proposed methodology demonstrated reasonable correlation between regions of high landslide susceptibility and observed shallow landslides within a 150-km2 region of the Oregon Coast Range when the water-height ratio was 0.5. The method may be improved by considering spatial hydrologic conditions and geology more explicitly.  相似文献   

9.
The objective of this study was to produce and evaluate a landslide susceptibility map for weathered granite soils in Deokjeok-ri Creek, South Korea. The relative effect (RE) method was used to determine the relationship between landslide causative factors (CFs) and landslide occurrence. To determine the effect of CFs on landslides, data layers of aspect, elevation, slope, internal relief, curvature, distance to drainage, drainage density, stream power index, sediment transport index, topographic wetness index, soil drainage character, soil type, soil depth, forest type, timber age, and geology were analyzed in a geographical information system (GIS) environment. A GIS-based landslide inventory map of 748 landslide locations was prepared using data from previous reports, aerial photographic interpretation, and extensive field work. A RE model was generated from a training set consisting of 673 randomly selected landslides in the inventory map, with the remaining 75 landslides used for validation of the susceptibility map. The results of the analysis were verified using the landslide location data. According to the analysis, the RE model had a success rate of 86.3 % and a predictive accuracy of 88.6 %. The validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide locations. The results of this study can therefore be used to mitigate landslide-induced hazards and to plan land use.  相似文献   

10.
This is the first landslide inventory map in the island of Lefkada integrating satellite imagery and reports from field surveys. In particular, satellite imagery acquired before and after the 2003 earthquake were collected and interpreted with the results of the field survey that took place 1 week after this strong (Mw?=?6.3) event. The developed inventory map indicates that the density of landslides decreases from west to east. Furthermore, the spatial distribution of landslides was statistically analyzed in relation to the geology and topography for investigating their influence to landsliding. This was accomplished by overlaying these causal factors as thematic layers with landslide distribution data. Afterwards, weight values of each factor were calculated using the landslide index method and a landslide susceptibility map was developed. The susceptibility map indicates that the highest susceptibility class accounts for 38 % of the total landslide activity, while the three highest classes that cover the 10 % of the surface area, accounting for almost the 85 % of the active landslides. Our model was validated by applying the approaches of success and prediction rate to the dataset of landslides that was previously divided into two groups based on temporal criteria, estimation and validation group. The outcome of the validation dataset was that the highest susceptibility class concentrates 18 % of the total landslide activity. However, taking into account the frequency of landslides within the three highest susceptibility classes, more than 85 %, the model is characterized as reliable for a regional assessment of earthquake-induced landslides hazard.  相似文献   

11.
In the last decades, physically based distributed models turned out rather promising to achieve the space–time assessment of shallow landslides at large spatial scale. This technical note deals with the application of a physically based stability model named Shallow Landslides Instability Prediction (SLIP), which has been adopted by the Department of National Civil Protection of Italy as a prototype early warning system for rainfall-induced shallow landslides on national scale. The model is used as a main methodology to create space–time shallow landslide susceptibility maps based on a simple deterministic slope-stability approach, combined with high-resolution rainfall information and geographic information system-based geospatial datasets. The safety factor as an index to measure slope instability is modeled as function of topographic, geologic, geotechnical and hydrologic variables. Although the main aim of this work was to prove the operational viability of such model on a nationwide domain and some simplification are adopted at this stage, hind cast tests on some relevant case histories of shallow landslides occurred between October 2009 and October 2011 showed that the model has skill in representing both timing and location of those shallow landslides.  相似文献   

12.
Mineralization with exchangeable rare earth element (REE) and yttrium (MEX-REY) has been recognized in the weathering profiles in South China since the early 1970's. This type of REY mineralization occurs in weathering profiles of parent rocks ranging in composition from granite to acidic volcanic rocks and lamprophyre. The majority of the known resources occurring in the weathering profiles of granitic rocks. Total resources of this type of REY amount to millions tons of rare earth oxides, and therefore represent one of the most important types of rare earth resources in China, particularly for heavy rare earth elements (HREE) and yttrium.Accumulation of REY in the weathering profiles of granitic rocks is strongly controlled by the resistance to weathering of the principal REY-bearing accessory minerals in the parent rocks; only a limited proportion of total REY (< 30%) is incorporated in the rock-forming minerals. MEX-REY more commonly occur in weathering profiles developed on granitic rocks within which most of the REY are incorporated in accessory minerals weakly resistant to weathering (doverite, parisite, etc.). For the well-developed weathering profiles, three horizons can be distinguished from surface downwards: the lateritic horizon (A), the weathered horizon (B), and the weathering front (C). Continuous leaching, coupled with low rate of denudation, results in the accumulation of REY in the subsurface horizons (the B and C horizons), and thus results in REE differentiation within the well-developed, layered, and mature weathering profiles. Exchangeable REY, which can be replaced by cations like NH4+ and Na+ etc. in electrolyte solutions and can be removed by complexing agents such as EDTA, are commonly the major form of REE occurrence in the B horizon. Cerium is enriched in the top layer (A horizon) and depleted in the subsurface horizons of the weathering profiles, most likely due to the oxidation of Ce(III) to Ce(IV) followed by cerianite formation or absorption onto clays and/or Fe and Al oxyhydroxides.  相似文献   

13.
Rare earth element (REE) geochemistry and mineralogy have been studied in the weathered crusts derived from the Early Yanshanian (Jurassic) biotite granites of Dabu and Dingnan, as well as in the Indosinian (Permian) muscovite–biotite granite of Aigao in southern Jiangxi province, China, and the weathered crusts and clay sediments on biotite granites in the Sanyo belt, SW Japan, that is, Okayama, Tanakami, and Naegi areas. In all of the weathered crusts, biotite and plagioclase commonly tend to decrease toward the upper part of the profile, whereas kaolinite and residual quartz and K‐feldspar increase. The weathered crusts of the Dingnan granites and some Naegi granites, which are characterized by the enrichment in light REE (LREE) in C horizons, have higher total REE (ΣREE) content than the parent REE‐enriched granites. Weathering of LREE‐bearing apatite and fluorocarbonates in the Dingnan granites and allanite and apatite in some Naegi granites may account for the leaching of LREE at the B horizons. The leached LREE must result in subsequent enrichment of LREE in the C horizons. The enrichment is probably associated with mainly adsorption onto kaolinite and partly formation of possible secondary LREE‐bearing minerals. In Japan it was found that REE mineralization occurs not in the weathered granitic crusts but in reworked clay sediments, especially kaolinite‐rich layers, derived mainly from the weathering materials of REE‐enriched granitic rocks. The clay sediments are more enriched in LREE, which likely adsorbed onto kaolinite. Concentration of heavy REE within almost all the weathered crusts and clay sediments, however, may reflect mainly residual REE‐bearing minerals such as zircon, which originated in the parent granitic rocks. The findings of the present study support the three processes for fractionation of the REE during weathering: (i) selective leaching of rocks containing both stable and unstable REE‐bearing minerals; (ii) adsorption onto clay minerals; and (iii) presence of possible secondary LREE‐bearing minerals.  相似文献   

14.
Weathered whole rock samples of five lithic units from Maine, Virginia, North Carolina and South Carolina were analyzed to evaluate the effect of chemical weathering on the Rb-Sr ages of the original rocks. Major element and turbidity analyses, as well as standard X-ray diffraction and petrographic studies were made on selected samples. All weathered granitic rocks are friable; several are almost saprolites. Volcanic rocks are powdery or are pitted as a result of the weathering of plagioclase phenocrysts. The weathering profiles studied all are young relative to the age of the unaltered rock. Considering the extent of weathering, however, ages of the weathered samples are remarkably close to the published ages for unaltered samples of the same units. Weathered samples have ages ranging from essentially the same as fresh samples to no more than 20% younger than the age obtained from the fresh samples. In one profile, we have attempted to quantify the extent of weathering: there is a positive correlation between our measure of the degree of weathering and per cent ‘lowering’ of the age. Weathering of plagioclase apparently has little effect on whole rock ages; ages are lowered significantly only where biotite and K-feldspar have undergone considerable alteration.  相似文献   

15.
The “Costa Viola” mountain ridge (southern Calabria), in the sector between Bagnara Calabra and Scilla, is particularly exposed to geo-hydrological risk conditions. The study area has repeatedly been affected by slope instability events in the last decades, mainly related to debris slides, rock falls and debris flows. These types of slope movements are among the most destructive and dangerous for people and infrastructures, and are characterized by abrupt onset and extremely rapid movements. Susceptibility evaluations to shallow landslides have been performed by only focusing on source activation. A logistic regression approach has been applied to estimating the presence/absence of sources in terms of probability, on the basis of linear statistical relationships with a set of territorial variables. An inventory map of 181 sources, obtained from interpretation of air photographs taken in 1954–1955, has been used as training set, and another map of 81 sources, extracted from 1990 to 1991 photographs, has been adopted for validation purposes. An initial set of 12 territorial variables (i.e. lithology, land use, soil sand percentage, elevation, slope angle, aspect, across-slope and down-slope curvatures, topographic wetness index, distance to road, distance to fault and index of daily rainfall) has been considered. The adopted regression procedure consists of the following steps: (1) parameterization of the independent variables, (2) sampling, (3) calibration, (4) application and (5) evaluation of the forecasting capability. The “best set” of variables could be identified by iteratively excluding one variable at a time, and comparing the ROC results. Through a sensitivity analysis, the role of the considered factors in predisposing shallow slope failures in the study area has been evaluated. The results obtained for the Costa Viola mountain ridge can be considered acceptable, as 98.1 % of the cells are correctly classified. According to the susceptibility map, the village of Scilla and its surroundings fall in the highest susceptibility class.  相似文献   

16.
The mechanism underlying rain-induced shallow landslides of non-welded ignimbrite is found to be a special type of weathering profile and the behavior of water infiltrating through that profile, according to our study of Ito ignimbrite in southern Kyushu, Japan. Rhyolitic volcanic glass, the primary component of ignimbrite, is first hydrated and dissolved, forming halloysite. Halloysite near ground surface is then transported through the ignimbrite by infiltrating water and becomes clogged in interstices to form clay bands. Suction monitoring across a weathering profile indicated that downward infiltration of water is disrupted once by a zone of less-permeable clay bands and again at the weathering front. This disruption at the front is caused by a capillary barrier effect caused by the structure where finer, weathered material overlies coarser, fresh material. This results in a well-defined weathering front, particularly beneath a slope where water flux is parallel to the front, whereas the front is transitional beneath a ridge top where the front is nearly horizontal and the water flux is normal to the front. Infiltrating water from rain increases the weight of weathered material and decreases the suction within the material, which is the final trigger of a shallow landslide of non-welded ignimbrite; long-term weathering, which proceeds on the order of years, provides slide material.  相似文献   

17.
The increasing availability of remotely sensed data offers a new opportunity to address landslide hazard assessment at larger spatial scales. A prototype global satellite-based landslide hazard algorithm has been developed to identify areas that may experience landslide activity. This system combines a calculation of static landslide susceptibility with satellite-derived rainfall estimates and uses a threshold approach to generate a set of ‘nowcasts’ that classify potentially hazardous areas. A recent evaluation of this algorithm framework found that while this tool represents an important first step in larger-scale near real-time landslide hazard assessment efforts, it requires several modifications before it can be fully realized as an operational tool. This study draws upon a prior work’s recommendations to develop a new approach for considering landslide susceptibility and hazard at the regional scale. This case study calculates a regional susceptibility map using remotely sensed and in situ information and a database of landslides triggered by Hurricane Mitch in 1998 over four countries in Central America. The susceptibility map is evaluated with a regional rainfall intensity–duration triggering threshold and results are compared with the global algorithm framework for the same event. Evaluation of this regional system suggests that this empirically based approach provides one plausible way to approach some of the data and resolution issues identified in the global assessment. The presented methodology is straightforward to implement, improves upon the global approach, and allows for results to be transferable between regions. The results also highlight several remaining challenges, including the empirical nature of the algorithm framework and adequate information for algorithm validation. Conclusions suggest that integrating additional triggering factors such as soil moisture may help to improve algorithm performance accuracy. The regional algorithm scenario represents an important step forward in advancing regional and global-scale landslide hazard assessment.  相似文献   

18.
Landslide hazard or susceptibility assessment is based on the selection of relevant factors which play a role on the slope instability, and it is assumed that landslides will occur at similar conditions to those in the past. The selected statistical method compares parametric maps with the landslide inventory map, and results are then extrapolated to the entire evaluated territory with a final product of landslide hazard or susceptibility map. Elements at risk are defined and analyzed in relation with landslide hazard, and their vulnerability is thus established. The landslide risk map presents risk scenarios and expected financial losses caused by landslides, and it utilizes prognoses and analyses arising from the landslide hazard map. However, especially the risk scenarios for future in a selected area have a significant importance, the literature generally consists of the landslide susceptibility assessment and papers which attempt to assess and construct the map of the landslide risk are not prevail. In the paper presented herein, landslide hazard and risk assessment using bivariate statistical analysis was applied in the landslide area between Hlohovec and Sered?? cities in the south-western Slovakia, and methodology for the risk assessment was explained in detail.  相似文献   

19.
Aykut Akgun 《Landslides》2012,9(1):93-106
The main purpose of this study is to compare the use of logistic regression, multi-criteria decision analysis, and a likelihood ratio model to map landslide susceptibility in and around the city of İzmir in western Turkey. Parameters, such as lithology, slope gradient, slope aspect, faults, drainage lines, and roads, were considered. Landslide susceptibility maps were produced using each of the three methods and then compared and validated. Before the modeling and validation, the observed landslides were separated into two groups. The first group was for training, and the other group was for validation steps. The accuracy of models was measured by fitting them to a validation set of observed landslides. For validation process, the area under curvature (AUC) approach was applied. According to the AUC values of 0.810, 0.764, and 0.710 for logistic regression, likelihood ratio, and multi-criteria decision analysis, respectively, logistic regression was determined to be the most accurate method among the other used landslide susceptibility mapping methods. Based on these results, logistic regression and likelihood ratio models can be used to mitigate hazards related to landslides and to aid in land-use planning.  相似文献   

20.
Landslide susceptibility zonation mapping is a fundamental procedure for geo-disaster management in tropical and sub-tropical regions. Recently, various landslide susceptibility zonation models have been introduced in Nepal with diverse approaches of assessment. However, validation is still a problem. Additionally, the role of various predisposing causative parameters for landslide activity is still not well understood in the Nepal Himalaya. To address these issues of susceptibility zonation and landslide activity, about 4,000 km2 area of central Nepal was selected for regional-scale assessment of landslide activity and susceptibility zonation mapping. In total, 655 new landslides and 9,229 old landslides were identified with the study area with the help of satellite images, aerial photographs, field data and available reports. The old landslide inventory was “blind landslide database” and could not explain the particular rainfall event responsible for the particular landslide. But considering size of the landslide, blind landslide inventory was reclassified into two databases: short-duration high-intensity rainfall-induced landslide inventory and long-duration low-intensity rainfall-induced landslide inventory. These landslide inventory maps were considered as proxy maps of multiple rainfall event-based landslide inventories. Similarly, all 9,884 landslides were considered for the activity assessment of predisposing causative parameters. For the Nepal Himalaya, slope, slope aspect, geology and road construction activity (anthropogenic cause) were identified as most affective predisposing causative parameters for landslide activity. For susceptibility zonation, multivariate approach was considered and two proxy rainfall event-based landslide databases were used for the logistic regression modelling, while a relatively recent landslide database was used in validation. Two event-based susceptibility zonation maps were merged and rectified to prepare the final susceptibility zonation map and its prediction rate was found to be more than 82 %. From this work, it is concluded that rectification of susceptibility zonation map is very appropriate and reliable. The results of this research contribute to a significant improvement in landslide inventory preparation procedure, susceptibility zonation mapping approaches as well as role of various predisposing causative parameters for the landslide activity.  相似文献   

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