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1.
The Thompson River valley, south of Ashcroft in British Columbia, Canada, has experienced several landslides since the mid-1800s. The national railways that run along the valley cross a number of these landslides. All the landslides occur in glacial deposits, typically sliding on weak clay layers. Some have failed rapidly to very rapidly and are currently inactive or showing deformation rates from a few millimeters to centimeters per year. An evaluation of satellite InSAR (Interferometric Synthetic Aperture Radar) using RADARSAT-2 images between September 2013 and November 2015 provides new insight into landslide displacements in the Thompson River valley. This information enhances the ongoing hazard management of unstable terrain. This paper presents the comparison of the InSAR measurements with other instrumentation (GPS and ShapeAccelArrays? -SAA) installed at one moving landslide and then addresses the extent and magnitude of the slope movements observed. InSAR was found to provide similar displacement values to those measured otherwise. The stable location showed displacements of +/?1 mm with an average near zero during the whole monitoring period. Six areas of slope movement were identified within the study area, all within or adjacent to the footprints of past landslides. The average line of sight (LOS) displacement rates range between 11 and 39 mm/year. Most of the landslides exhibited seasonal variations in velocity that corresponds to changes in river elevation in the valley.  相似文献   

2.
The prediction of landslide movement acceleration is a complex problem, among others identified for deep-seated landslides, and represents a crucial step for risk assessment. Within the scope of this problem, the objective of this paper is to explore a modelling method that enables the study of landslide function and facilitates displacement predictions based on a limited data set. An inverse modelling approach is proposed for predicting the temporal evolution of landslide movement based on rainfall and displacement velocities. Initially, the hydrogeology of the studied landslides was conceptualised based on correlative analyses. Subsequently, we applied an inverse model with a Gaussian-exponential transfer function to reproduce the displacements. This method was tested on the Grand Ilet (GI) and Mare-à-Poule-d’Eau (HB) landslides on Reunion Island in the Indian Ocean. We show that the behaviour of landslides can be modelled by inverse models with a bimodal transfer function using a Gaussian-exponential impulse response. The cumulative displacements over 7 years of modelling (2 years of calibration period for GI, and 4 years for HB) were reproduced with an RMSE above 0.9. The characteristics of the bimodal transfer function are directly related to the hydrogeological functioning demonstrated by the correlative analyses: the rapid reaction of a landslide can be associated with the effect of a preferential flow path on groundwater level variations. Thus, this study shows that the inverse model using a Gaussian-exponential transfer function is a powerful tool for predicting deep-seated landslide movements and for studying how they function. Beyond modelling displacements, our approach effectively demonstrates its ability to contribute relevant data for conceptualising the sliding mechanisms and hydrogeology of landslides.  相似文献   

3.
Large landslides and deep-seated gravitational slope deformations (DSGSD) represent an important geo-hazard in relation to the deformation of large structures and infrastructures and to the associated secondary landslides. DSGSD movements, although slow (from a few millimetres to several centimetres per year), can continue for very long periods, producing large cumulative displacements and undergoing partial or complete reactivation. Therefore, it is important to map the activity of such phenomena at a regional scale. Ground surface displacements at DSGSD typically range close to the detection limit of monitoring equipment but are suitable for synthetic aperture radar (SAR) interferometry. In this paper, permanent scatterers (PSInSAR?) and SqueeSAR? techniques are used to analyse the activity of 133 DSGSD, in the Central Italian Alps. Statistical indicators for assigning a degree of activity to slope movements from displacement rates are discussed together with methods for analysing the movement and activity distribution within each landslide. In order to assess if a landslide is active or not, with a certain degree of reliability, three indicators are considered as optimal: the mean displacement rate, the activity index (ratio of active PS, displacement rate larger than standard deviation, overall PS) and the nearest neighbor ratio, which allows to describe the degree of clustering of the PS data. According to these criteria, 66% of the phenomena are classified as active in the monitored period 1992–2009. Finally, a new methodology for the use of SAR interferometry data to attain a classification of landslide kinematic behaviour is presented. This methodology is based on the interpretation of longitudinal ground surface displacement rate profiles in the light of numerical simulations of simplified failure geometries. The most common kinematic behaviour is rotational, amounting to 41 DSGSDs, corresponding to the 62.1% of the active phenomena.  相似文献   

4.
The increased socio-economic significance of landslides has resulted in the application of statistical methods to assess their hazard, particularly at medium scales. These models evaluate where, when and what size landslides are expected. The method presented in this study evaluates the landslide hazard on the basis of homogenous susceptible units (HSU). HSU are derived from a landslide susceptibility map that is a combination of landslide occurrences and geo-environmental factors, using an automated segmentation procedure. To divide the landslide susceptibility map into HSU, we apply a region-growing segmentation algorithm that results in segments with statistically independent spatial probability values. Independence is tested using Moran’s I and a weighted variance method. For each HSU, we obtain the landslide frequency from the multi-temporal data. Temporal and size probabilities are calculated using a Poisson model and an inverse-gamma model, respectively. The methodology is tested in a landslide-prone national highway corridor in the northern Himalayas, India. Our study demonstrates that HSU can replace the commonly used terrain mapping units for combining three probabilities for landslide hazard assessment. A quantitative estimate of landslide hazard is obtained as a joint probability of landslide size, of landslide temporal occurrence for each HSU for different time periods and for different sizes.  相似文献   

5.
Post-disaster very high resolution(VHR) satellite data are potential sources to provide detailed information on damage and geological changes for a large area in a short time.In this paper,we studied landslides triggered by the M_w 6.9 earthquake in Sikkim,India which occurred on 18 September 2011 using VHR data from Cartosat-1,GeoEye-1,QuickBird-2 and WorldView-2 satellites.Since the earthquake-affected area is located in mostly inaccessible Himalayan terrain,VHR data from these satellites provided a unique opportunity for quick and synoptic assessment of the damage.Using visual change analysis technique through comparison of pre- and post-earthquake images,we assessed the damage caused by the event.A total of 123 images acquired from eight satellites,covering an area of4105 km2 were analysed and 1196 new landslides triggered by the earthquake were mapped.Road blockages and severely affected villages were also identified.Geological assessment of the terrain highlighted linear disposition of landslides along existing fault scarps,suggesting a reactivation of fault.The landslide inventory map prepared from VHR images also showed a good correlation with the earthquake shake map.Results showed that several parts of north Sikkim,particularly Mangan and Chungthang,which are close to the epicentre,were severely affected by the earthquake,and that the event-based landslide inventory map can be used in future earthquake-triggered landslide susceptibility assessment studies.  相似文献   

6.
The paper deals with a methodology for quantitative landslide hazard and risk assessments over wide-scale areas. The approach was designed to fulfil the following requirements: (1) rapid investigation of large study areas; (2) use of elementary information, in order to satisfy the first requirement and to ensure validation, repetition and real time updating of the assessments every time new data are available; (3) computation of the landslide frequency of occurrence, in order to compare objectively different hazard conditions and to minimize references to qualitative hazard attributes such as activity states. The idea of multi-temporal analysis set forth by Cardinali et al. (Nat Hazards Earth Syst Sci 2:57–72, 2002), has been stressed here to compute average recurrence time for individual landslides and to forecast their behaviour within reference time periods. The method is based on the observation of the landslide activity through aerial-photo surveys carried out in several time steps. The output is given by a landslide hazard map showing the mean return period of landslides reactivation. Assessing the hazard in a quantitative way allows for estimating quantitatively the risk as well; thus, the probability of the exposed elements (such as people and real estates) to suffer damages due to the occurrence of landslides can be calculated. The methodology here presented is illustrated with reference to a sample area in Central Italy (Umbria region), for which both the landslide hazard and risk for the human life are analysed and computed. Results show the powerful quantitative approach for assessing the exposure of human activities to the landslide threat for a best choice of the countermeasures needed to mitigate the risk.An erratum to this article can be found at  相似文献   

7.
A methodology for monitoring system of an impoundment-induced landslide in Three Gorges Reservoir Area, China is introduced. Currently, based on landslide geological classification, the monitoring regions and methods which include types of monitoring instruments, placement and calibration precision of instruments, and appropriate periods for instrumental placement is confirmed. To optimize the monitoring system, sensitivity analysis of displacements and the water table in landslides affected by reservoir surface fluctuation is completed to determine the layout of the monitoring cross sections and the monitoring points. As a case study, the behavior of displacements and the potential fluctuation of the water table in the Shiliushubao landslide, produced by the gradual water impoundment at Three Gorges Reservoir, has been simulated using 3D finite element method analysis. The sensitivity analysis of Shiliushubao landslide is investigated by the fuzzy set evaluation method. As a result, the monitoring network of Shiliushubao landslide is established.  相似文献   

8.
 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. Received: 17 December 1999 · Accepted: 21 March 2000  相似文献   

9.
晚更新世以来,特别是全新世以来,黄土高原西北部发育了多期次的滑坡事件。临夏盆地巴谢河流域较好地保留了多期次滑坡的遗存,有研究历史滑坡发育规律的良好素材。文章通过详细的野外调查,初步厘清了滑坡空间分布及新老滑坡相互叠置关系,总结得到本地区滑坡的四种发展类型:压裂型深层黄土-泥岩滑坡、滑移型深层黄土-泥岩滑坡、蠕变型中浅层黄土-泥岩滑坡和塌滑型黄土滑坡。不同时期发育的滑坡在野外呈现明显不同的特征:发育于晚更新世的古滑坡有圈椅状的地形和高陡的后缘陡壁,滑坡堆积体已固结,堆积体表面冲沟发育;发育于全新世早期的老滑坡除了具有圈椅状地形和高陡后壁外,堆积体较为松散,堆积平台形态较为完整;发育于全新世晚期的新滑坡则保留了更多的滑坡特征,可见滑坡后缘和侧缘裂缝。巴谢河流域滑坡大多有多次滑动的迹象,不同期次的滑坡相互重叠,在同一范围发生多次滑动,形成多级滑坡堆积平台。滑坡埋压动植物、滑坡洼地短期水体沉积物等有着明显的滑坡指示意义。通过采集此类样品,利用14C和光释光等测年手段,获取了本地区一系列滑坡事件的年龄。对测年数据进行统计分析,得到巴谢河流域晚更新世以来的五个滑坡高发时段,分别为100~63 kaBP、45.2~41.5 kaBP、33.3~28.2 kaBP、22.5~15.2 kaBP和10.4~0.2 kaBP。以上滑坡高发时段的推断将为认识去环境变迁提供证据。  相似文献   

10.
Statistical approach to earthquake-induced landslide susceptibility   总被引：13，自引：0，他引：13  
Susceptibility analysis for predicting earthquake-induced landslides has most frequently been done using deterministic methods; multivariate statistical methods have not previously been applied. In this study, however, we introduce a statistical methodology that uses the intensity of earthquake shaking as a landslide triggering factor. This methodology is applied in a study of shallow earthquake-induced landslides in central western Taiwan. The results show that we can accurately interpret landslide distribution in the study area and predict the occurrence of landslides in neighboring regions. This susceptibility model is capable of predicting shallow landslides induced during an earthquake scenario with similar range of ground shaking, without requiring the use of geotechnical, groundwater or failure depth data.  相似文献   

11.
If prediction of a debris landslide is to be completed, the first problem is how to determine and correlate the dynamic factors. The special composition and complicated geological conditions of debris landslides have many dynamic factors influencing displacement and stability. Correlations are generally very complicated. The relationship and sequence of factors is too complex to be completed by traditional mathematical model. In order to solve the problem above, a systematical study of the quantitative and qualitative dynamic factors using a model of the quantitative theory was performed based on the displacements of Xintan landslide, China. Rainfall was found to be the most important dynamic factor among the six factors controlling displacements. Relative importance sequence and correlation was also established. All prediction results agree with the mechanism and displacement pattern of the Xintan landslide. Optimized measures of prevention and control for debris landslides can be completed with correlation of the dynamic factors by means of the quantitative theory model.  相似文献   

12.
岩土体含水量对滑坡,尤其是土质滑坡的稳定性具有极大的影响。本文以三峡库区秭归段内土质滑坡作为研究对象,利用Sentinel-1雷达数据反演地表岩土体含水量来替代传统的湿度指数因子,在保持其他因子不变的情况下,构建二元逻辑回归模型进行滑坡易发性评价。结果表明,利用成功率曲线对结果进行分析,采用岩土体含水量因子时预测精度达到80.2%,高于采用地形湿度指数的77.2%。利用雷达数据反演得到的岩土体含水量代替地形湿度指数进行滑坡易发性评价精度较高、预测能力较强。  相似文献   

13.
我国黄土梁峁区历史强震频发,地震触发的滑坡等地质灾害是导致震后大量人员伤亡和财产损失的主要因素。1718年甘肃通渭7.5级地震在极震区附近诱发了300多处大规模滑坡,其中在甘谷县磐安镇（原永宁镇）地震使得“北山南移,覆压永宁全镇”,导致3万余人伤亡。以往的研究认为,该类地震滑坡是黄土沿古地形面的滑动,属于黄土滑坡。通过详细野外地质灾害调查,对通渭地震诱发滑坡的分布特征、灾害类型和失稳模式进行了研究;以研究区最大的滑坡——尉家湾巨型地震滑坡为典型案例,结合工程地质钻探,对该滑坡的深部结构特征进行了分析,并对其力学机制进行了探讨。研究发现,该类滑坡的滑动面主要位于下伏新近纪泥岩中,且深度大,属于一类典型的黄土-泥岩复合滑坡;这一新成果和发现能够更好地解译历史文献记载当时的地震滑坡现象。同时,新的成果和认识可以为我国西北黄土梁峁区河谷两岸具有类似地质地貌条件的城镇在强震作用下的地震滑坡早期识别提供参考和启示。  相似文献   

14.
Landslide zoning in a part of the Garhwal Himalayas   总被引：21，自引：1，他引：20  
 The Himalayas are undergoing constant rupturing in the thrust belt zone in the Garhwal Himalayas, due to which earthquake and mass movement activity is triggered. These processes of mass movement and landslides have been constantly modifying the landscape. Landslides are one of the indicators of the geomorphological modifications taking place in this active and fragile terrain. This work is aimed at providing another example of landslide susceptibility mapping based on geological and geomorphological attributes. The data collected from aerial photographs, topographic sheets and the image suggests that there is a correlation between the distribution of landslides and some of the geological and geomorphological factors, for example, the distance from an active fault, relative relief and slope. Parameters like factor of safety, altitude, relief, slope and the distance from the fault lineament have been included in the study. A rating system has been applied to the factors for arriving at a quantitative estimate of landslide susceptibility for each physiographic unit. Since terrain classification forms the foundation of this work, the entire study can be grouped into two sequential activities: (1) the terrain classification and (2) landslide susceptibility mapping. The result is the landslide susceptibility zoning map presented. The landslides have not been classified with respect to time and may represent the final result of the on-going geological, geomorphological and seismic activity since the Holocene period or late Pleistocene time when the glaciers retreated. The area chosen for the study lies between Badri gad and Barni gad in Yamuna valley region of the Garhwal Himalaya where a very large scale investment is in the pipe line for Hydroelectric power generation. Received: 12 August 1993 · Accepted: 13 January 1998  相似文献   

15.
滑坡形态要素及发育特征研究是古(老)滑坡野外调查和遥感影像识别以及复杂艰险山区基础设施选线(址)工程地质研究的重要内容。青藏高原东缘地质环境条件复杂,在内外动力地质作用下该区域发育有大量古(老)滑坡体。本文以位于青藏高原东缘毛垭坝盆地的大型老滑坡——乱石包滑坡为例,以滑坡塘形态要素为研究对象,综合利用无人机摄影测量技术、水文地质调查、自然电位地球物理勘探以及渗流数值模拟等研究方法,探明了乱石包滑坡塘形态要素几何特征和渗流发育特征并揭示了其成因和演化机制。研究结果表明乱石包滑坡发生后在滑坡后缘平台和主滑壁处形成低洼地形,地下水沿该处发育的理塘—德巫断裂产生泉水出露,地下水持续补给最终形成体积约为5505 m3的大型滑坡塘,最大水深位于滑坡塘西侧,深度约为2 m。滑坡运动过程中在滑坡后缘平台下部形成次级滑壁,在上部滑坡塘高水头长期作用下,物质结构松散破碎的滑坡后缘平台西侧坡体内形成内部渗流并在陡峭的次级滑壁中部产生泉水出露,进而在下部滑坡洼地处形成体积约为35 m3的小型滑坡塘。长期渗流作用下,堆积体内部存在渗流潜蚀风险,建议后期针对次级滑壁上泉...  相似文献   

16.
Back-analysis is broadly used for approaching geotechnical problems when monitoring data are available and information about the soils properties is of poor quality.For landslide stability assessment back-analysis calibration is usually carried out by time consuming trial-and-error procedure.This paper presents a new automatic Decision Support System that supports the selection of the soil parameters for three-dimensional models of landslides based on monitoring data.The method considering a pool of possible solutions,generated through permutation of soil parameters,selects the best ten configurations that are more congruent with the measured displacements.This reduces the operator biases while on the other hand allows the operator to control each step of the computation.The final selection of the preferred solution among the ten best-fitting solutions is carried out by an operator.The operator control is necessary as he may include in the final decision process all the qualitative elements that cannot be included in a qualitative analysis but nevertheless characterize a landslide dynamic as a whole epistemological subject,for example on the base of geomorphological evidence.A landslide located in Northeast Italy has been selected as example for showing the system potentiality.The proposed method is straightforward,scalable and robust and could be useful for researchers and practitioners.  相似文献   

17.
The 1989 Loma Prieta, California earthquake (moment magnitude, M=6.9) generated landslides throughout an area of about 15,000 km2 in central California. Most of these landslides occurred in an area of about 2000 km2 in the mountainous terrain around the epicenter, where they were mapped during field investigations immediately following the earthquake. The distribution of these landslides is investigated statistically, using regression and one-way analysis of variance (ANOVA) techniques to determine how the occurrence of landslides correlates with distance from the earthquake source, slope steepness, and rock type. The landslide concentration (defined as the number of landslide sources per unit area) has a strong inverse correlation with distance from the earthquake source and a strong positive correlation with slope steepness. The landslide concentration differs substantially among the various geologic units in the area. The differences correlate to some degree with differences in lithology and degree of induration, but this correlation is less clear, suggesting a more complex relationship between landslide occurrence and rock properties.  相似文献   

18.
In this paper, a quantitative landslide hazard model is presented for transportation lines, with an example for a road and railroad alignment, in parts of Nilgiri hills in southern India. The data required for the hazard assessment were obtained from historical records available for a 21-year period from 1987 to 2007. A total of 901 landslides from cut slopes along the railroad and road alignment were included in the inventory. The landslides were grouped into three magnitude classes based on the landslide type, volume, scar depth, and run-out distance. To calculate landslide hazard, we estimated the total number of individual landslides per kilometer of the (rail) road for different return periods, based on the relationship between past landslides (recorded in our database) and triggering events. These were multiplied by the probability that the landslides belong to a given magnitude class. This gives the hazard for a given return period expressed as the number of landslides of a given magnitude class per kilometer of (rail) road. The relationship between the total number of landslides and the return period was established using a Gumbel distribution model, and the probability of landslide magnitude was obtained from frequency–volume statistics. The results of the analysis indicate that the total number of landslides, from 1- to 50-year return period, varies from 56 to 197 along the railroad and from 14 to 82 along the road. In total, 18 hazard scenarios were generated using the three magnitude classes and six return periods (1, 3, 5, 15, 25, and 50 years). The hazard scenarios derived from the model form the basis for future direct and indirect landslide risk analysis along the transportation lines. The model was validated with landslides that occurred in the year 2009.  相似文献   

19.
In this paper, for the first time, disk-based discontinuous deformation analysis (DDA) is applied to simulate a real landslide triggered by an earthquake. For this purpose, the kinematic behaviour of the Donghekou landslide triggered by the Wenchuan earthquake is simulated and the results obtained using disk-based DDA are compared with actual data. The comparisons show that there is a good agreement between the results obtained using disk-based DDA and observed data. The simulation results provided an understanding of the failure behaviour and temporal evolution of the landslide. This study shows that disk-based DDA is a practical numerical tool that can be used to simulate the post-failure behaviour of landslides triggered by an earthquake.  相似文献   

20.
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   

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