Articles de revues : « Landslide Size Distribution »

1

Piegari, E., R. Di Maio et L. Milano. « Characteristic scales in landslide modelling ». Nonlinear Processes in Geophysics 16, n^o 4 (22 juillet 2009) : 515–23. http://dx.doi.org/10.5194/npg-16-515-2009.

Texte intégral

Résumé :

Abstract. Landslides are natural hazards occurring in response to triggers of different origins, which can act with different intensities and durations. Despite the variety of conditions that cause a landslide, the analysis of landslide inventories has shown that landslide events associated with different triggers can be characterized by the same probability distribution. We studied a cellular automaton, able to reproduce the landslide frequency-size distributions from catalogues. From the comparison between our synthetic probability distribution and the landslide area probability distribution of three landslide inventories, we estimated the typical size of a single cell of our cellular automaton model to be from 35–100 m2, which is important information if we are interested in monitoring a test area. To determine the probability of occurrence of a landslide of size s, we show that it is crucial to get information about the rate at which the system is approaching instability rather than the nature of the trigger. By varying such a driving rate, we find how the probability distribution changes and, in correspondence, how the size and the lifetime of the most probable events evolve. We also introduce a landslide-event magnitude scale based on the driving rate. Large values of the proposed intensity scale are related to landslide events with a fast approach to instability in a long distance of time, while small values are related to landslide events close together in time and approaching instability slowly.

Styles APA, Harvard, Vancouver, ISO, etc.

2

Roering, Joshua J., Kevin M. Schmidt, Jonathan D. Stock, William E. Dietrich et David R. Montgomery. « Shallow landsliding, root reinforcement, and the spatial distribution of trees in the Oregon Coast Range ». Canadian Geotechnical Journal 40, n^o 2 (1 avril 2003) : 237–53. http://dx.doi.org/10.1139/t02-113.

Texte intégral

Résumé :

The influence of root reinforcement on shallow landsliding has been well established through mechanistic and empirical studies, yet few studies have examined how local vegetative patterns influence slope stability. Because root networks spread outward from trees, the species, size, and spacing of trees should influence the spatial distribution of root strength. We documented the distribution and characteristics of trees adjacent to 32 shallow landslides that occurred during 1996 in the Oregon Coast Range. Although broadly classified as a conifer-dominated forest, we observed sparse coniferous and abundant hardwood trees near landslide scars in an industrial forest (Mapleton) that experienced widespread burning in the 19th century. In industrial forests that were burned, selectively harvested, and not replanted (Elliott State Forest), swordfern was ubiquitous near landslides, and we observed similar numbers of live conifer and hardwood trees proximal to landslide scarps. We demonstrate that root strength quantified in landslide scarps and soil pits correlates with a geometry-based index of root network contribution derived from mapping the size, species, condition, and spacing of local trees, indicating that root strength can be predicted by mapping the distribution and characteristics of trees on potentially unstable slopes. In our study sites, landslides tend to occur in areas of reduced root strength, suggesting that to make site-specific predictions of landslide occurrence slope stability analyses must account for the diversity and distribution of vegetation in potentially unstable terrain.Key words: slope stability, vegetation, root strength, shallow landslide, debris flow, Oregon Coast Range.

Styles APA, Harvard, Vancouver, ISO, etc.

3

Litoseliti, Aspasia, Ioannis K. Koukouvelas, Konstantinos G. Nikolakopoulos et Vasiliki Zygouri. « An Event-Based Inventory Approach in Landslide Hazard Assessment : The Case of the Skolis Mountain, Northwest Peloponnese, Greece ». ISPRS International Journal of Geo-Information 9, n^o 7 (20 juillet 2020) : 457. http://dx.doi.org/10.3390/ijgi9070457.

Texte intégral

Résumé :

Assessment of landslide hazard across mountains is imperative for public safety. Pre- and post-earthquake landslide mapping envisage that landslides show significant size changes during earthquake activity. One of the purposes of earthquake-induced landslide investigation is to determine the landslide state and geometry and draw conclusions on their mobility. This study was based on remote sensing data that covered 72 years, and focused on the west slopes of the Skolis Mountains, in the northwest Peloponnese. On 8 June 2008, during the strong Movri Mountain earthquake (Mw = 6.4), we mapped the extremely abundant landslide occurrence. Historical seismicity and remote sensing data indicate that the Skolis Mountain west slope is repeatedly affected by landslides. The impact of the earthquakes was based on the estimation of Arias intensity in the study area. We recognized that 89 landslides developed over the last 72 years. These landslides increased their width (W), called herein as inflation or their length (L), termed as enlargement. Length and width changes were used to describe their aspect ratio (L/W). Based on the aspect ratio, the 89 landslides were classified into three types: I, J, and Δ. Taluses, developed at the base of the slope and belonging to the J- and Δ-landslide types, are supplied by narrow or irregular channels. During the earthquakes, the landslide channels migrated upward and downward, outlining the mobility of the earthquake-induced landslides. Landslide mobility was defined by the reach angle. The reach angle is the arctangent of the landslide’s height to length ratio. Furthermore, we analyzed the present slope stability across the Skolis Mountain by using the landslide density (LD), landslide area percentage (LAP), and landslide frequency (LF). All these parameters were used to evaluate the spatial and temporal landslide distribution and evolution with the earthquake activity. These results can be considered as a powerful tool for earthquake-induced landslide disaster mitigation

Styles APA, Harvard, Vancouver, ISO, etc.

4

Kubwimana, Désiré, Lahsen Ait Brahim, Pascal Nkurunziza, Antoine Dille, Arthur Depicker, Louis Nahimana, Abdellah Abdelouafi et Olivier Dewitte. « Characteristics and Distribution of Landslides in the Populated Hillslopes of Bujumbura, Burundi ». Geosciences 11, n^o 6 (17 juin 2021) : 259. http://dx.doi.org/10.3390/geosciences11060259.

Texte intégral

Résumé :

Accurate and detailed multitemporal inventories of landslides and their process characterization are crucial for the evaluation of landslide hazards and the implementation of disaster risk reduction strategies in densely-populated mountainous regions. Such investigations are, however, rare in many regions of the tropical African highlands, where landslide research is often in its infancy and not adapted to the local needs. Here, we have produced a comprehensive multitemporal investigation of the landslide processes in the hillslopes of Bujumbura, situated in the landslide-prone East African Rift. We inventoried more than 1200 landslides by combining careful field investigation and visual analysis of satellite images, very-high-resolution topographic data, and historical aerial photographs. More than 20% of the hillslopes of the city are affected by landslides. Recent landslides (post-1950s) are mostly shallow, triggered by rainfall, and located on the steepest slopes. The presence of roads and river quarrying can also control their occurrence. Deep-seated landslides typically concentrate in landscapes that have been rejuvenated through knickpoint retreat. The difference in size distributions between old and recent deep-seated landslides suggests the long-term influence of potentially changing slope-failure drivers. Of the deep-seated landslides, 66% are currently active, those being mostly earthflows connected to the river system. Gully systems causing landslides are commonly associated with the urbanization of the hillslopes. Our results provide a much more accurate record of landslide processes and their impacts in the region than was previously available. These insights will be useful for land management and disaster risk reduction strategies.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Zhang, Jianqiang, Cees J. van Westen, Hakan Tanyas, Olga Mavrouli, Yonggang Ge, Samjwal Bajrachary, Deo Raj Gurung, Megh Raj Dhital et Narendral Raj Khanal. « How size and trigger matter : analyzing rainfall- and earthquake-triggered landslide inventories and their causal relation in the Koshi River basin, central Himalaya ». Natural Hazards and Earth System Sciences 19, n^o 8 (15 août 2019) : 1789–805. http://dx.doi.org/10.5194/nhess-19-1789-2019.

Texte intégral

Résumé :

Abstract. Inventories of landslides caused by different triggering mechanisms, such as earthquakes, extreme rainfall events or anthropogenic activities, may show different characteristics in terms of distribution, contributing factors and frequency–area relationships. The aim of this research is to study such differences in landslide inventories and the effect they have on landslide susceptibility assessment. The study area is the watershed of the transboundary Koshi River in the central Himalaya, shared by China, Nepal and India. Detailed landslide inventories were generated based on visual interpretation of remote-sensing images and field investigation for different time periods and triggering mechanisms. Maps and images from the period 1992 to 2015 were used to map 5858 rainfall-triggered landslides, and after the 2015 Gorkha earthquake, an additional 14 127 coseismic landslides were mapped. A set of topographic, geological and land cover factors were employed to analyze their correlation with different types and sizes of landslides. The frequency–area distributions of rainfall- and earthquake-triggered landslides (ETLs) have a similar cutoff value and power-law exponent, although the ETLs might have a larger frequency of a smaller one. In addition, topographic factors varied considerably for the two triggering events, with both altitude and slope angle showing significantly different patterns for rainfall-triggered and earthquake-triggered landslides. Landslides were classified into two size groups, in combination with the main triggering mechanism (rainfall- or earthquake-triggered). Susceptibility maps for different combinations of landslide size and triggering mechanism were generated using logistic regression analysis. The different triggers and sizes of landslide data were used to validate the models. The results showed that susceptible areas for small- and large-size rainfall- and earthquake-triggered landslides differed substantially.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Xu, C., J. B. H. Shyu et X. W. Xu. « Landslides triggered by the 12 January 2010 Mw 7.0 Port-au-Prince, Haiti, earthquake : visual interpretation, inventory compiling and spatial distribution statistical analysis ». Natural Hazards and Earth System Sciences Discussions 2, n^o 2 (10 février 2014) : 1259–331. http://dx.doi.org/10.5194/nhessd-2-1259-2014.

Texte intégral

Résumé :

Abstract. The 12 January 2010 Port-au-Prince, Haiti, earthquake (Mw 7.0) triggered tens of thousands of landslides. The purpose of this study is to investigate the correlations of the occurrence of landslides and their erosion thicknesses with topographic factors, seismic parameters, and their distance from roads. A total of 30 828 landslides triggered by the earthquake covered a total area of 15.736 km2, distributed in an area more than 3000 km2, and the volume of landslide accumulation materials is estimated to be about 29 700 000 m3. These landslides are of various types, mostly belonging to shallow disrupted landslides and rock falls, but also include coherent deep-seated landslides and rock slides. These landslides were delineated using pre- and post-earthquake high-resolutions satellite images. Spatial distribution maps and contour maps of landslide number density, landslide area percentage, and landslide erosion thickness were constructed in order to analyze the spatial distribution patterns of co-seismic landslides. Statistics of size distribution and morphometric parameters of co-seismic landslides were carried out and were compared with other earthquake events in the world. Four proxies of co-seismic landslide abundance, including landslides centroid number density (LCND), landslide top number density (LTND), landslide area percentage (LAP), and landslide erosion thickness (LET) were used to correlate co-seismic landslides with various landslide controlling parameters. These controlling parameters include elevation, slope angle, slope aspect, slope curvature, topographic position, distance from drainages, lithology, distance from the epicenter, distance from the Enriquillo–Plantain Garden fault, distance along the fault, and peak ground acceleration (PGA). A comparison of these impact parameters on co-seismic landslides shows that slope angle is the strongest impact parameter on co-seismic landslide occurrence. Our co-seismic landslide inventory is much more detailed than other inventories in several previous publications. Therefore, we carried out comparisons of inventories of landslides triggered by the Haiti earthquake with other published results and proposed possible reasons of any differences. We suggest that the empirical functions between earthquake magnitude and co-seismic landslides need to update on the basis of the abundant and more complete co-seismic landslide inventories recently available.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Bostjančić, Iris, Radovan Avanić, Tihomir Frangen et Mirja Pavić. « Spatial distribution and geometric characteristics of landslides with special reference to geological units in the area of Slavonski Brod, Croatia ». Geologia Croatica 75, n^o 1 (28 février 2022) : 3–16. http://dx.doi.org/10.4154/gc.2022.03.

Texte intégral

Résumé :

A preliminary analysis of landslide spatial distribution and their geometric characteristics is presented for the area of Slavonski Brod, located in the northeastern part of Croatia and belonging to the Pannonian Basin System. A landslide inventory for the study area of 55.1 km2 is accomplished for the first time, based on the visual interpretation of a high resolution LiDAR digital terrain model. In total, 854 landslide polygons are delineated, corresponding to an average density of 15.5 landslides per square kilometre. The average landslide area is 839 m2, and most of the landslides can be classified as small landslides (76 %). The spatial relationship between landslides and geological units is analysed and expressed as a landslide index. The Late Pannonian sands with silts and gravel interlayers and Pliocene clay, sands, gravels, and coal are determined as the units that are most susceptible to landslide processes. The majority of landslides (85 %) are concentrated within these two units, for which a detailed analysis is performed, determining the morphometric parameters (slope and relief) and drainage network. The parameters’ classes that create favourable preconditions to slope instabilities are defined, based on the landslide density within individual classes. Besides, the geometric characteristics of landslides (size and shape) within these two units are compared. The results serve as the basis for further investigations. They help to foresee the area of future landslides through landslide susceptibility maps, and offer a better understanding of the influence of fluvial-denudation and slope processes on recent landscape evolution and form.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Xu, C., J. B. H. Shyu et X. Xu. « Landslides triggered by the 12 January 2010 Port-au-Prince, Haiti, Mw ; = 7.0 earthquake : visual interpretation, inventory compiling, and spatial distribution statistical analysis ». Natural Hazards and Earth System Sciences 14, n^o 7 (21 juillet 2014) : 1789–818. http://dx.doi.org/10.5194/nhess-14-1789-2014.

Texte intégral

Résumé :

Abstract. The 12 January 2010 Port-au-Prince, Haiti, earthquake (Mw= 7.0) triggered tens of thousands of landslides. The purpose of this study is to investigate the correlations of the occurrence of landslides and the thicknesses of their erosion with topographic, geologic, and seismic parameters. A total of 30 828 landslides triggered by the earthquake covered a total area of 15.736 km2, distributed in an area more than 3000 km2, and the volume of landslide accumulation materials is estimated to be about 29 700 000 m3. These landslides are of various types, mostly belonging to shallow disrupted landslides and rock falls, but also include coherent deep-seated landslides and rock slides. These landslides were delineated using pre- and post-earthquake high-resolution satellite images. Spatial distribution maps and contour maps of landslide number density, landslide area percentage, and landslide erosion thickness were constructed in order to analyze the spatial distribution patterns of co-seismic landslides. Statistics of size distribution and morphometric parameters of co-seismic landslides were carried out and were compared with other earthquake events in the world. Four proxies of co-seismic landslide abundance, including landslides centroid number density (LCND), landslide top number density (LTND), landslide area percentage (LAP), and landslide erosion thickness (LET) were used to correlate co-seismic landslides with various environmental parameters. These parameters include elevation, slope angle, slope aspect, slope curvature, topographic position, distance from drainages, lithology, distance from the epicenter, distance from the Enriquillo–Plantain Garden fault, distance along the fault, and peak ground acceleration (PGA). A comparison of these impact parameters on co-seismic landslides shows that slope angle is the strongest impact parameter on co-seismic landslide occurrence. Our co-seismic landslide inventory is much more detailed than other inventories in several previous publications. Therefore, we carried out comparisons of inventories of landslides triggered by the Haiti earthquake with other published results and proposed possible reasons for any differences. We suggest that the empirical functions between earthquake magnitude and co-seismic landslides need to be updated on the basis of the abundant and more complete co-seismic landslide inventories recently available.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Marc, Odin, Robert Behling, Christoff Andermann, Jens M. Turowski, Luc Illien, Sigrid Roessner et Niels Hovius. « Long-term erosion of the Nepal Himalayas by bedrock landsliding : the role of monsoons, earthquakes and giant landslides ». Earth Surface Dynamics 7, n^o 1 (25 janvier 2019) : 107–28. http://dx.doi.org/10.5194/esurf-7-107-2019.

Texte intégral

Résumé :

Abstract. In active mountain belts with steep terrain, bedrock landsliding is a major erosional agent. In the Himalayas, landsliding is driven by annual hydro-meteorological forcing due to the summer monsoon and by rarer, exceptional events, such as earthquakes. Independent methods yield erosion rate estimates that appear to increase with sampling time, suggesting that rare, high-magnitude erosion events dominate the erosional budget. Nevertheless, until now, neither the contribution of monsoon and earthquakes to landslide erosion nor the proportion of erosion due to rare, giant landslides have been quantified in the Himalayas. We address these challenges by combining and analysing earthquake- and monsoon-induced landslide inventories across different timescales. With time series of 5 m satellite images over four main valleys in central Nepal, we comprehensively mapped landslides caused by the monsoon from 2010 to 2018. We found no clear correlation between monsoon properties and landsliding and a similar mean landsliding rate for all valleys, except in 2015, where the valleys affected by the earthquake featured ∼5–8 times more landsliding than the pre-earthquake mean rate. The long-term size–frequency distribution of monsoon-induced landsliding (MIL) was derived from these inventories and from an inventory of landslides larger than ∼0.1 km2 that occurred between 1972 and 2014. Using a published landslide inventory for the Gorkha 2015 earthquake, we derive the size–frequency distribution for earthquake-induced landsliding (EQIL). These two distributions are dominated by infrequent, large and giant landslides but under-predict an estimated Holocene frequency of giant landslides (> 1 km3) which we derived from a literature compilation. This discrepancy can be resolved when modelling the effect of a full distribution of earthquakes of variable magnitude and when considering that a shallower earthquake may cause larger landslides. In this case, EQIL and MIL contribute about equally to a total long-term erosion of ∼2±0.75 mm yr−1 in agreement with most thermo-chronological data. Independently of the specific total and relative erosion rates, the heavy-tailed size–frequency distribution from MIL and EQIL and the very large maximal landslide size in the Himalayas indicate that mean landslide erosion rates increase with sampling time, as has been observed for independent erosion estimates. Further, we find that the sampling timescale required to adequately capture the frequency of the largest landslides, which is necessary for deriving long-term mean erosion rates, is often much longer than the averaging time of cosmogenic 10Be methods. This observation presents a strong caveat when interpreting spatial or temporal variability in erosion rates from this method. Thus, in areas where a very large, rare landslide contributes heavily to long-term erosion (as the Himalayas), we recommend 10Be sample in catchments with source areas > 10 000 km2 to reduce the method mean bias to below ∼20 % of the long-term erosion.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Rabby, Yasin Wahid, et Yingkui Li. « Landslide Inventory (2001–2017) of Chittagong Hilly Areas, Bangladesh ». Data 5, n^o 1 (25 décembre 2019) : 4. http://dx.doi.org/10.3390/data5010004.

Texte intégral

Résumé :

Landslides are a frequent natural hazard in Chittagong Hilly Areas (CHA), Bangladesh, which causes the loss of lives and damage to the economy. Despite this, an official landslide inventory is still lacking in this area. In this paper, we present a landslide inventory of this area prepared using the visual interpretation of Google Earth images (Google Earth Mapping), field mapping, and a literature search. We mapped 730 landslides that occurred from January 2001 to March 2017. Different landslide attributes including type, size, distribution, state, water content, and triggers are presented in the dataset. In this area, slide and flow were the two dominant types of landslides. Out of the five districts (Bandarban, Chittagong, Cox’s Bazar, Khagrachari, and Rangamati), most (55%) of the landslides occurred in the Chittagong and Rangamati districts. About 45% of the landslides were small (<100 m2) in size, while the maximum size of the detected landslides was 85202 m2. This dataset will help to understand the characteristics of landslides in CHA and provide useful guidance for policy implementation.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Marc, Odin, Jens M. Turowski et Patrick Meunier. « Controls on the grain size distribution of landslides in Taiwan : the influence of drop height, scar depth and bedrock strength ». Earth Surface Dynamics 9, n^o 4 (17 août 2021) : 995–1011. http://dx.doi.org/10.5194/esurf-9-995-2021.

Texte intégral

Résumé :

Abstract. The size of grains delivered to rivers by hillslope processes is thought to be a key factor controlling sediment transport, long-term erosion and the information recorded in sedimentary archives. Recently, models have been developed to estimate the grain size distribution produced in soil, but these models may not apply to active orogens where high erosion rates on hillslopes are driven by landsliding. To date, relatively few studies have focused on landslide grain size distributions. Here, we present grain size distributions (GSDs) obtained by grid-by-number sampling on 17 recent landslide deposits in Taiwan, and we compare these GSDs to the geometrical and physical properties of the landslides, such as their width, area, rock type, drop height and estimated scar depth. All slides occurred in slightly metamorphosed sedimentary units, except two, which occurred in younger unmetamorphosed shales, with a rock strength that is expected to be 3–10 times weaker than their metamorphosed counterparts. For 11 landslides, we did not observe substantial spatial variations in the GSD over the deposit. However, four landslides displayed a strong grain size segregation on their deposit, with the overall GSD of the downslope toe sectors being 3–10 times coarser than apex sectors. In three cases, we could also measure the GSD inside incised sectors of the landslides deposits, which presented percentiles that were 3–10 times finer than the surface of the deposit. Both observations could be due to either kinetic sieving or deposit reworking after the landslide failure, but we cannot explain why only some deposits had strong segregation. Averaging this spatial variability, we found the median grain size of the deposits to be strongly negatively correlated with drop height, scar width and depth. However, previous work suggests that regolith particles and bedrock blocks should coarsen with increasing depth, which is the inverse of our observations. Accounting for a model of regolith coarsening with depth, we found that the ratio of the estimated original bedrock block size to the deposit median grain size (D50) of the deposit was proportional to the potential energy of the landslide normalized to its bedrock strength. Thus, the studied landslides agree well with a published, simple fragmentation model, even if that model was calibrated on rock avalanches with larger volume and stronger bedrock than those featured in our dataset. Therefore, this scaling may serve for future modeling of grain size transfer from hillslopes to rivers, with the aim to better understanding landslide sediment evacuation and coupling to river erosional dynamics.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Argentin, Anne-Laure, Jörg Robl, Günther Prasicek, Stefan Hergarten, Daniel Hölbling, Lorena Abad et Zahra Dabiri. « Controls on the formation and size of potential landslide dams and dammed lakes in the Austrian Alps ». Natural Hazards and Earth System Sciences 21, n^o 5 (27 mai 2021) : 1615–37. http://dx.doi.org/10.5194/nhess-21-1615-2021.

Texte intégral

Résumé :

Abstract. Controls on landsliding have long been studied, but the potential for landslide-induced dam and lake formation has received less attention. Here, we model possible landslides and the formation of landslide dams and lakes in the Austrian Alps. We combine a slope criterion with a probabilistic approach to determine landslide release areas and volumes. We then simulate the progression and deposition of the landslides with a fluid dynamic model. We characterize the resulting landslide deposits with commonly used metrics, investigate their relation to glacial land-forming and tectonic units, and discuss the roles of the drainage system and valley shape. We discover that modeled landslide dams and lakes cover a wide volume range. In line with real-world inventories, we further found that lake volume increases linearly with landslide volume in the case of efficient damming – when an exceptionally large lake is dammed by a relatively small landslide deposit. The distribution and size of potential landslide dams and lakes depends strongly on local topographic relief. For a given landslide volume, lake size depends on drainage area and valley geometry. The largest lakes form in glacial troughs, while the most efficient damming occurs where landslides block a gorge downstream of a wide valley, a situation preferentially encountered at the transition between two different tectonic units. Our results also contain inefficient damming events, a damming type that exhibits different scaling of landslide and lake metrics than efficient damming and is hardly reported in inventories. We assume that such events also occur in the real world and emphasize that their documentation is needed to better understand the effects of landsliding on the drainage system.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Zhang, Ming, Fei Wang, Gu Jie Mouse, Wei Tao Luo, Hong Wu Zhang et Yao Ru Liu. « Experimental Investigation on the Segregation of Landslide Dam Materials ». Applied Mechanics and Materials 580-583 (juillet 2014) : 2103–7. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.2103.

Texte intégral

Résumé :

Large landslides usually dam lakes that may easily fail and then result in catastrophic flood threatening the population downstream. The grain size composition within landslide dams is considered as a vital factor that impacts the timing of failure and the resulting magnitude of flood. Therefore, experiments were conducted to investigate the features of size distribution in accumulation bodies. The results indicate that the grain size distribution varies in different parts of the deposits. The inverse grading phenomenon can be observed. Grains in the front of the deposit are coarser, while grains in the rear are finer. For the front of the deposit, the grains in the middle are finer than the other two sides. The grain size segregation is believed to be the governing mechanism that contributes to this special distribution. The speculations of the grain size distribution inside the landslide dam are presented.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Hashiba, H., et M. Sonobe. « EXTRACTION OF SCATTERED SMALL-SCALE LANDSLIDES DISTRIBUTION BY OBJECT-BASED CLASSIFICATION USING OPTICAL HIGH-RESOLUTION SATELLITE IMAGES ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2020 (21 août 2020) : 1213–18. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2020-1213-2020.

Texte intégral

Résumé :

Abstract. Continuous heavy rain for a long duration over mountainous terrain, where the elevation is relatively low and the topography is complex leads to multiple small-scale landslides over a wide area. Detailed investigations of small-scale landslides have been effectively carried out using optical high-resolution satellite images with spatial resolution of about 2 m or less. In this study, the sediment-related disaster caused by heavy rain in northern Kyushu, Japan that occurred in July 2017 was selected as a typical example of small-scale landslide. For this landslide event, the applicability of the conventional superpixel segmentation for landslide separation was examined. The applicability of the representative SLIC and SLICO methods in the superpixel segmentation method by image interpretation in the case of a large number of small-scale landslides in a wide area was assessed. These results suggest that in the case of such a disaster, segmentation by the SLICO method will be better. In addition, the set value of the area size for the area division was systematically examined from the distribution tendency of the average NDVI value in the divided area. It was shown that the landslide region can be extracted with relatively high accuracy by the land cover classification process by the NN method by using the appropriate region size examined by the SLICO method.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Oli, Tej Raj. « Landslide Hazard Assessment and Distribution Mapping : A Case from Triveni Rural Municipality, Nepal ». American Journal of Geospatial Technology 1, n^o 1 (29 août 2022) : 34–43. http://dx.doi.org/10.54536/ajgt.v1i1.468.

Texte intégral

Résumé :

An application of GIS for landslide hazard assessment using multivariate statistical analysis, mapping, and the evaluation of the hazard maps is crucial for disaster risk reduction. Landslides are the rapid downward movement of a mass of rock, earth or artificial fill to the slope. The study was conducted the Khara of Triveni Rural municipality of Rukum West district and it covers three wards (3, 4 & 5) of rural municipality covering the total area of about 33.52 square kilometres located in the Karnali province of Nepal which is under the pressure of high road construction activities. Data used to construct the landslide distribution map and hazard assessments were obtained from the direct field, and mapping using GIS. More data sources and verifications were made from the rural municipality, published articles and journals, topographical and geological maps, google images and aerial photographs and other digital sources. To determine the factors and classes influencing land sliding, the layers of topographic factors derived from a digital elevation model, geology, and land use/land covers were analyzed and the results were used for landslide distribution mapping and hazard analyses. From the landslide inventory of more than 200 landslides that were occurred during the last five years since 2015, the landslide distribution map, landslide-size distribution map and hazard level of sliding graphics were presented. Hazard map of the study area shows 4.34% area lies in the high hazard level, 53.64% on moderate hazard level and 42.02% in low hazard level in the study area. The results would give insights to the landslide distribution in the area that could support rural municipality for shaping disaster risk reduction policies and strategies.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Piegari, E., R. Di Maio et A. Avella. « Recurrence time distribution and temporal clustering properties of a cellular automaton modelling landslide events ». Nonlinear Processes in Geophysics 20, n^o 6 (5 décembre 2013) : 1071–78. http://dx.doi.org/10.5194/npg-20-1071-2013.

Texte intégral

Résumé :

Abstract. Reasonable prediction of landslide occurrences in a given area requires the choice of an appropriate probability distribution of recurrence time intervals. Although landslides are widespread and frequent in many parts of the world, complete databases of landslide occurrences over large periods are missing and often such natural disasters are treated as processes uncorrelated in time and, therefore, Poisson distributed. In this paper, we examine the recurrence time statistics of landslide events simulated by a cellular automaton model that reproduces well the actual frequency-size statistics of landslide catalogues. The complex time series are analysed by varying both the threshold above which the time between events is recorded and the values of the key model parameters. The synthetic recurrence time probability distribution is shown to be strongly dependent on the rate at which instability is approached, providing a smooth crossover from a power-law regime to a Weibull regime. Moreover, a Fano factor analysis shows a clear indication of different degrees of correlation in landslide time series. Such a finding supports, at least in part, a recent analysis performed for the first time of an historical landslide time series over a time window of fifty years.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Fu, Sheng, Lixia Chen, Tsehaie Woldai, Kunlong Yin, Lei Gui, Deying Li, Juan Du, Chao Zhou, Yong Xu et Zhipeng Lian. « Landslide hazard probability and risk assessment at the community level : a case of western Hubei, China ». Natural Hazards and Earth System Sciences 20, n^o 2 (26 février 2020) : 581–601. http://dx.doi.org/10.5194/nhess-20-581-2020.

Texte intégral

Résumé :

Abstract. Small communities living in mountainous terrain in Hubei province are often affected by landslides. Previous studies by the China Geological Survey focused on the 1:100 000 scale. Therefore, a more detailed assessment, especially at the community level, is urgently required by local governments for risk management. In this study, we conducted a more detailed semiquantitative landslide and risk assessment at the community level using a scale of 1:10 000. We applied the probabilistic method to assess landslide spatial, temporal, and size probabilities, while the hazard and risk assessment were considered for four return periods (5, 10, 20, and 50 years) and two size scenarios (landslide volume). The spatial probability from susceptibility mapping with an accuracy of 84 % indicates that the major controlling factors are Quaternary deposits and weathered eluvium from Ordovician limestones. This study revealed that most building areas in hazard maps are at the foot of major slopes with very high hazard probabilities, and therefore we computed the potential loss of life and property for each slope. The results reveal that 1530 people and USD 18 million worth of property were at risk of landslides within a 50-year return period and a landslide volume of 50 000 m3. The longer the return period is, the higher the hazard probability is. Compared with the classic inverse gamma and power law distribution of landslide magnitude and frequency, the function by the ordinary least squares method is more suitable for landslide size probability analysis of the study area. According to these methods, the proposed procedure of landslide risk assessment proves more useful than the existing data from the 1:100 000 scale in western Hubei, China.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Mergili, M., et H. J. Chu. « Integrated statistical modelling of spatial landslide probability ». Natural Hazards and Earth System Sciences Discussions 3, n^o 9 (24 septembre 2015) : 5677–715. http://dx.doi.org/10.5194/nhessd-3-5677-2015.

Texte intégral

Résumé :

Abstract. Statistical methods are commonly employed to estimate spatial probabilities of landslide release at the catchment or regional scale. Travel distances and impact areas are often computed by means of conceptual mass point models. The present work introduces a fully automated procedure extending and combining both concepts to compute an integrated spatial landslide probability: (i) the landslide inventory is subset into release and deposition zones. (ii) We employ a simple statistical approach to estimate the pixel-based landslide release probability. (iii) We use the cumulative probability density function of the angle of reach of the observed landslide pixels to assign an impact probability to each pixel. (iv) We introduce the zonal probability i.e. the spatial probability that at least one landslide pixel occurs within a zone of defined size. We quantify this relationship by a set of empirical curves. (v) The integrated spatial landslide probability is defined as the maximum of the release probability and the product of the impact probability and the zonal release probability relevant for each pixel. We demonstrate the approach with a 637 km2 study area in southern Taiwan, using an inventory of 1399 landslides triggered by the typhoon Morakot in 2009. We observe that (i) the average integrated spatial landslide probability over the entire study area corresponds reasonably well to the fraction of the observed landside area; (ii) the model performs moderately well in predicting the observed spatial landslide distribution; (iii) the size of the release zone (or any other zone of spatial aggregation) influences the integrated spatial landslide probability to a much higher degree than the pixel-based release probability; (iv) removing the largest landslides from the analysis leads to an enhanced model performance.

Styles APA, Harvard, Vancouver, ISO, etc.

19

Korte, David M., et Abdul Shakoor. « Landslide Susceptibility and Soil Loss Estimates for Drift Creek Watershed, Lincoln County, Oregon ». Environmental and Engineering Geoscience 26, n^o 2 (27 mai 2020) : 167–84. http://dx.doi.org/10.2113/eeg-2251.

Texte intégral

Résumé :

ABSTRACT Drift Creek watershed, Lincoln County, Oregon, is a source of drinking water as well as a reproductive habitat for endangered salmon and trout species. Landslides, exacerbated by logging, are suspected as a cause of water quality deterioration in the watershed. To investigate the impact of landslides on water quality, we mapped landslide distribution and susceptibility, determined engineering properties of landslide-prone soil and rock, and estimated soil loss resulting from landslide-derived sediment within 30 m of Strahler third-order-or-higher streams in the watershed. We mapped 570 landslides using LiDAR imaging, orthophotographs, and field observations. We used logistic regression to determine the most significant variables contributing to landslide occurrence and to create a watershed-scale landslide susceptibility map. Siletz River Volcanics and the sedimentary Tyee Formation make up 85 percent of the watershed, with the sedimentary Yamhill and Nestucca formations making up the majority of the rest. Sedimentary rocks dominate in the Upper Drift Creek watershed, and volcanic dominate in the lower portion. The largest landslide deposits and the highest susceptibility occur in the sedimentary rock formations. The Siletz River Volcanics has a larger abundance of landslides than the sedimentary rock formations, but they are smaller in size with lower susceptibility of occurrence. The soil loss model indicates that the average annual soil loss from landslide deposits in the Upper Drift Creek watershed is 65 tons/acre/yr compared to 29 tons/acre/yr in the Lower Drift Creek watershed. The model also indicates that soil loss from areas along roads in the watershed is high.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Gariano, S. L., O. Petrucci et F. Guzzetti. « Changes in the occurrence of rainfall-induced landslides in Calabria, southern Italy, in the 20th century ». Natural Hazards and Earth System Sciences 15, n^o 10 (13 octobre 2015) : 2313–30. http://dx.doi.org/10.5194/nhess-15-2313-2015.

Texte intégral

Résumé :

Abstract. Only a few studies have investigated the geographical and temporal variations in the frequency and distribution of rainfall-induced landslides, and the consequences of the variations on landslide risk. Lack of information limits the possibility to evaluate the impact of environmental and climate changes on landslide frequency and risk. Here, we exploit detailed historical information on landslides and rainfall in Calabria, southern Italy, between 1921 and 2010 to study the temporal and the geographical variation in the occurrence of rainfall-induced landslides and in their impact on the population. We exploit a catalogue with information on historical landslides from June 1920 to December 2010, and daily rainfall records obtained by a network of 318 rain gauges in the same period, to reconstruct 448 493 rainfall events (RE). Combining the rainfall and the landslide information, we obtain a catalogue of 1466 rainfall events with landslides (REL), where an REL is the occurrence of one or more landslide during or immediately after a rainfall event. We find that (i) the geographical and the temporal distributions of the rainfall-induced landslides have changed in the observation period, (ii) the monthly distribution of the REL has changed in the observation period, and (iii) the average and maximum cumulated event rainfall that have resulted in landslides in the recent 30-year period 1981–2010 are lower than the rainfall necessary to trigger landslides in previous periods, whereas the duration of the RE that triggered landslides has remained the same. We attribute the changes to variations in the rainfall conditions and to an increased vulnerability of the territory. To investigate the variations in the impact of REL on the population, we compared the number of REL in each of the 409 municipalities in Calabria with the size of the population in the municipalities measured by national Censuses conducted in 1951, 1981, and 2011. We adopted two strategies; the first strategy considered impact as IREL = #REL / P, and the second strategy measured impact as RREL = #REL × P, where #REL is the total number of REL in a period, and P is the size of the population in the same period and geographical area. The analysis has revealed a complex pattern of changes in the impact of rainfall-induced landslides in Calabria in the recent past, with areas where IREL and RREL have increased, and other areas where they have decreased. Municipalities where IREL has increased are mainly in the mountains, and municipalities where RREL has increased are mainly along the coasts. The complexity of the changes in the frequency and impact of rainfall-induced landslides observed in Calabria suggests that it remains difficult and uncertain to predict the possible variations in the frequency and impact of landslide in response to future climatic and environmental changes.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Huang, Yidan, et Lingkan Yao. « Size distribution law of earthquake-triggered landslides in different seismic intensity zones ». Nonlinear Processes in Geophysics 28, n^o 2 (16 avril 2021) : 167–79. http://dx.doi.org/10.5194/npg-28-167-2021.

Texte intégral

Résumé :

Abstract. The Ms 8.0 Wenchuan earthquake in 2008 and Ms 7.0 Lushan earthquake in 2013 produced thousands of landslides in the southern region of the Longmen Mountains in China. We conducted field investigations and analyzed remote sensing data to determine the distribution law of earthquake-triggered landslides. The results show a strong negative power law relationship between the size and frequency of landslides in VII, VIII, and IX seismic intensity zones, a weak power law in the X seismic intensity zone, and a lognormal distribution in the XI seismic intensity zone. Landslide density increases with increasing seismic intensity. A sandpile cellular automata model was built under the conceptual framework of self-organized criticality theory to simulate earthquake-induced landslides. Data from the simulations demonstrate that, with increasing disturbance intensity, the dynamical mechanism of the sandpile model changes from a strong power law to a weak power law and then to a lognormal distribution. Results from shaking table experiments of a one-sided slope sandpile show that, for peak ground acceleration (PGA) in the range of 0.075–0.125 g, the relation between the amount and frequency of sand follows a negative power law. For PGA between 0.15 and 0.25 g, the relation obeys a lognormal distribution. This verifies that the abovementioned distribution of earthquake-induced landslides should be a universal law from a physical viewpoint and may apply to other areas. This new perspective may be used to guide the development of an inventory of earthquake-triggered landslides and provide a scientific basis for their prediction.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Hurst, M. D., M. A. Ellis, K. R. Royse, K. A. Lee et K. Freeborough. « Controls on the magnitude-frequency scaling of an inventory of secular landslides ». Earth Surface Dynamics 1, n^o 1 (11 décembre 2013) : 67–78. http://dx.doi.org/10.5194/esurf-1-67-2013.

Texte intégral

Résumé :

Abstract. Linking landslide size and frequency is important at both human and geological timescales for quantifying both landslide hazards and the effectiveness of landslides in the removal of sediment from evolving landscapes. The statistical behaviour of the magnitude-frequency of landslide inventories is usually compiled following a particular triggering event such as an earthquake or storm, and their statistical behaviour is often characterised by a power-law relationship with a small landslide rollover. The occurrence of landslides is expected to be influenced by the material properties of rock and/or regolith in which failure occurs. Here we explore the statistical behaviour and the controls of a secular landslide inventory (SLI) (i.e. events occurring over an indefinite geological time period) consisting of mapped landslide deposits and their underlying lithology (bedrock or superficial) across the United Kingdom. The magnitude-frequency distribution of this secular inventory exhibits an inflected power-law relationship, well approximated by either an inverse gamma or double Pareto model. The scaling exponent for the power-law scaling of medium to large landslides is α = −1.71 ± 0.02. The small-event rollover occurs at a significantly higher magnitude (1.0–7.0 × 10−3 km2) than observed in single-event landslide records (~ 4 × 10−3 km2). We interpret this as evidence of landscape annealing, from which we infer that the SLI underestimates the frequency of small landslides. This is supported by a subset of data where a complete landslide inventory was recently mapped. Large landslides also appear to be under-represented relative to model predictions. There are several possible reasons for this, including an incomplete data set, an incomplete landscape (i.e. relatively steep slopes are under-represented), and/or temporal transience in landslide activity during emergence from the last glacial maximum toward a generally more stable late-Holocene state. The proposed process of landscape annealing and the possibility of a transient hillslope response have the consequence that it is not possible to use the statistical properties of the current SLI database to rigorously constrain probabilities of future landslides in the UK.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Bernard, Thomas G., Dimitri Lague et Philippe Steer. « Beyond 2D landslide inventories and their rollover : synoptic 3D inventories and volume from repeat lidar data ». Earth Surface Dynamics 9, n^o 4 (26 août 2021) : 1013–44. http://dx.doi.org/10.5194/esurf-9-1013-2021.

Texte intégral

Résumé :

Abstract. Efficient and robust landslide mapping and volume estimation is essential to rapidly infer landslide spatial distribution, to quantify the role of triggering events on landscape changes, and to assess direct and secondary landslide-related geomorphic hazards. Many efforts have been made to develop landslide mapping methods, based on 2D satellite or aerial images, and to constrain the empirical volume–area (V–A) relationship which, in turn, would allow for the provision of indirect estimates of landslide volume. Despite these efforts, major issues remain, including the uncertainty in the V–A scaling, landslide amalgamation and the underdetection of landslides. To address these issues, we propose a new semiautomatic 3D point cloud differencing method to detect geomorphic changes, filter out false landslide detections due to lidar elevation errors, obtain robust landslide inventories with an uncertainty metric, and directly measure the volume and geometric properties of landslides. This method is based on the multiscale model-to-model cloud comparison (M3C2) algorithm and was applied to a multitemporal airborne lidar dataset of the Kaikōura region, New Zealand, following the Mw 7.8 earthquake of 14 November 2016. In a 5 km2 area, the 3D point cloud differencing method detects 1118 potential sources. Manual labeling of 739 potential sources shows the prevalence of false detections in forest-free areas (24.4 %), due to spatially correlated elevation errors, and in forested areas (80 %), related to ground classification errors in the pre-earthquake (pre-EQ) dataset. Combining the distance to the closest deposit and signal-to-noise ratio metrics, the filtering step of our workflow reduces the prevalence of false source detections to below 1 % in terms of total area and volume of the labeled inventory. The final predicted inventory contains 433 landslide sources and 399 deposits with a lower limit of detection size of 20 m2 and a total volume of 724 297 ± 141 087 m3 for sources and 954 029 ± 159 188 m3 for deposits. Geometric properties of the 3D source inventory, including the V–A relationship, are consistent with previous results, except for the lack of the classically observed rollover of the distribution of source area. A manually mapped 2D inventory from aerial image comparison has a better lower limit of detection (6 m2) but only identifies 258 landslide scars, exhibits a rollover in the distribution of source area of around 20 m2, and underestimates the total area and volume of 3D-detected sources by 72 % and 58 %, respectively. Detection and delimitation errors in the 2D inventory occur in areas with limited texture change (bare-rock surfaces, forests) and at the transition between sources and deposits that the 3D method accurately captures. Large rotational/translational landslides and retrogressive scars can be detected using the 3D method irrespective of area's vegetation cover, but they are missed in the 2D inventory owing to the dominant vertical topographic change. The 3D inventory misses shallow (< 0.4 m depth) landslides detected using the 2D method, corresponding to 10 % of the total area and 2 % of the total volume of the 3D inventory. Our data show a systematic size-dependent underdetection in the 2D inventory below 200 m2 that may explain all or part of the rollover observed in the 2D landslide source area distribution. While the 3D segmentation of complex clustered landslide sources remains challenging, we demonstrate that 3D point cloud differencing offers a greater detection sensitivity to small changes than a classical difference of digital elevation models (DEMs). Our results underline the vast potential of 3D-derived inventories to exhaustively and objectively quantify the impact of extreme events on topographic change in regions prone to landsliding, to detect a variety of hillslope mass movements that cannot be captured by 2D landslide mapping, and to explore the scaling properties of landslides in new ways.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Jeandet, L., P. Steer, D. Lague et P. Davy. « Coulomb Mechanics and Relief Constraints Explain Landslide Size Distribution ». Geophysical Research Letters 46, n^o 8 (17 avril 2019) : 4258–66. http://dx.doi.org/10.1029/2019gl082351.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

25

Hurst, M. D., M. A. Ellis, K. R. Royse, K. A. Lee et K. Freeborough. « Controls on the magnitude-frequency scaling of an inventory of secular landslides ». Earth Surface Dynamics Discussions 1, n^o 1 (1 juillet 2013) : 113–39. http://dx.doi.org/10.5194/esurfd-1-113-2013.

Texte intégral

Résumé :

Abstract. Linking landslide size and frequency is important at both human and geological time-scales for quantifying both landslide hazards and the effectiveness of landslides in the removal of sediment from evolving landscapes. Landslide inventories are usually compiled following a particular triggering event such as an earthquake or storm, and their statistical behavior is typically characterized by an inflected power-law relationship. The occurrence of landslides is expected to be influenced by the material properties of rock and/or regolith in which failure occurs. Here we explore the statistical behavior and the controls of a secular landslide inventory (SLI) (i.e. events occurring over an indefinite time period) consisting of mapped landslide deposits and their underlying lithology (bedrock or superficial) across the United Kingdom. The magnitude-frequency distribution of this secular inventory exhibits an inflected power law relationship, well approximated by an inverse Gamma or double Pareto model. The scaling exponent for the power-law relationship is α = −1.76. The small-event rollover occurs at a significantly higher magnitude than observed in single-event landslide records, which we interpret as evidence of “landscape annealing” at these relatively short length-scales, noting the corollary that a secular dataset will tend to underestimate the frequency of small landslides. This is supported by a subset of data where a complete landslide inventory was recently mapped. Large landslides also appear to be under-represented relative to model predictions, which we interpret as a non-linear or transient landscape response as the UK emerged from the last glacial maximum and through relatively volatile conditions toward a generally more stable late Holocene climate.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Dewitte, O., et A. Demoulin. « Morphometry and kinematics of landslides inferred from precise DTMs in West Belgium ». Natural Hazards and Earth System Sciences 5, n^o 2 (3 mars 2005) : 259–65. http://dx.doi.org/10.5194/nhess-5-259-2005.

Texte intégral

Résumé :

Abstract. The Flemish Ardennes (W Belgium) are known to be affected by deep-seated landslides. The assessment of the landslide reactivation hazard requires understanding the driving processes and delimiting precisely not only the landslide boundaries but especially that of their most active parts. Precise 3D models of 13 landslides were produced by digital stereophotogrammetry using aerial photographs of different dates. Dealing with photographs at the scale 1:25000 or larger, we obtained for each model an accuracy better than 0.5m. As a first result, the main size parameters of the landslides (width, length, depth, volume, ...) are easily computed. Moreover, the obtained DTMs may be subtracted from each other in order to determine the apparent vertical displacement of each pixel during the interval of time considered. Provided that more than 2 epochs are documented, such DTMs not only supply precise information about distribution and style of the landslide activity but may also point to temporal variations in this activity. The subtraction of DTMs allows us to give an estimation of the volume of the "uplifted" and "collapsed" terrains between two epochs.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Wu, Chun-Yi, et Po-Kai Chou. « Prediction of total landslide volume in watershed scale under rainfall events using a probability model ». Open Geosciences 13, n^o 1 (1 janvier 2021) : 944–62. http://dx.doi.org/10.1515/geo-2020-0284.

Texte intégral

Résumé :

Abstract This study established a probability model based on the landslide spatial and size probabilities to predict the possible volume and locations of landslides in watershed scale under rainfall events. First, we assessed the landslide spatial probability using a random forest landslide susceptibility model including intrinsic causative factors and extrinsic rainfall factors. Second, we calculated the landslide volume probability using the Pearson type V distribution. Lastly, these probabilities were joined to predict possible landslide volume and locations in the study area, the Taipei Water Source Domain, under rainfall events. The possible total landslide volume in the watershed changed from 1.7 million cubic meter under the event with 2-year recurrence interval to 18.2 million cubic meter under the event with 20-year recurrence interval. Approximately 62% of the total landslide volume triggered by the rainfall events was concentrated in 20% of the slope units. As the recurrence interval of the events increased, the slope units with large landslide volume tended to concentrate in the midstream of Nanshi River subwatershed. The results indicated the probability model posited can be used not only to predict total landslide volume in watershed scale, but also to determine the possible locations of the slope units with large landslide volume.

Styles APA, Harvard, Vancouver, ISO, etc.

28

Hölbling, Daniel, Raphael Spiekermann, Andrea Binn et Harley Betts. « Analysing and visualizing spatio-temporal landslide patterns ». Abstracts of the ICA 1 (15 juillet 2019) : 1–2. http://dx.doi.org/10.5194/ica-abs-1-116-2019.

Texte intégral

Résumé :

Abstract. Landslide erosion is a serious land management problem in many parts of the world. In New Zealand, a combination of steep erodible hill country, frequent and intense rainstorms, and recent forest clearance for pastoral farming has led to extensive landslide erosion in many parts of the country. Effective mitigation measures against landslide erosion and its consequences require a detailed understanding of the history, location, extent, and severity of landsliding. Consequently, the preparation and availability of comprehensive and meaningful landslide inventories and spatial representation using advanced cartographic techniques can support mitigation of landslide erosion, risk communication, decision making and land management.Remote sensing and new geospatial technologies have significantly increased objectivity and efficiency of geomorphological mapping, while at the same time recent developments in GIScience allow different theoretical perspectives on space, time, processes, and systems to be merged (Bishop et al., 2012; Napieralski et al., 2013). The complexity of natural phenomena such as landslides requires advanced and innovative image analysis methods for adequate and effective landslide inventory mapping (Guzzetti et al., 2012). Remote sensing data is well suited for detecting landslides and for deriving spatio-temporal landslide patterns. Manually or semi-automatically mapped landslides from optical satellite images or aerial photographs can be used as input for creating landslide pattern or hotspot maps, which constitute an easy-to-grasp visual representation of the worst landslide-affected areas following landslide triggering events such as heavy rainstorms.For analysing and visualizing spatio-temporal landslide patterns we use historical and recent aerial photography from five different dates, ranging from 1944 to 2011, for a study site near the town of Pahiatua, New Zealand. Landslide hotspots are identified from the distribution of semi-automatically detected landslides using object-based image analysis (OBIA) (cf. Hölbling et al., 2016). The development of semi-automated image classification techniques such as OBIA offers the potential to considerably improve existing manual landslide mapping techniques, in particular the time needed for landslide detection can be significantly reduced while achieving acceptable mapping accuracies. The semi-automatically identified landslide polygons are rasterized at 1&thinsp;m cell size and aggregated to 25&thinsp;m pixel resolution by calculating the sum of 1&thinsp;m landslide pixels per 25&thinsp;m cell. The resulting map is a landslide cover or density map which displays the proportion of landslide area covering each pixel (625&thinsp;m2) in percent. Figure 1 shows an example of the identified landslide hotspots based on the OBIA mapping using the aerial photograph from 2005. The comparison of the landslide hotspots based on the OBIA mapping with those based on manually mapped landslides shows very similar results for all periods. Advanced visualization techniques and cartographic representations are finally used to illustrate the evolution of the landslide hotspots over space and time. Such a space-time and multidimensional representation of landslide patterns can reveal relevant new information about past and recent landslide activity and can be valuable for risk communication and targeted mitigation of landslide erosion.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Bellugi, Dino G., David G. Milledge, Kurt M. Cuffey, William E. Dietrich et Laurel G. Larsen. « Controls on the size distributions of shallow landslides ». Proceedings of the National Academy of Sciences 118, n^o 9 (26 février 2021) : e2021855118. http://dx.doi.org/10.1073/pnas.2021855118.

Texte intégral

Résumé :

Rainfall-triggered shallow landslides are destructive hazards and play an important role in landscape processes. A theory explaining the size distributions of such features remains elusive. Prior work connects size distributions to topography, but field-mapped inventories reveal pronounced similarities in the form, mode, and spread of distributions from diverse landscapes. We analyze nearly identical distributions occurring in the Oregon Coast Range and the English Lake District, two regions of strikingly different topography, lithology, and vegetation. Similarity in minimum sizes at these sites is partly explained by theory that accounts for the interplay of mechanical soil strength controls resisting failure. Maximum sizes, however, are not explained by current theory. We develop a generalized framework to account for the entire size distribution by unifying a mechanistic slope stability model with a flexible spatial-statistical description for the variability of hillslope strength. Using hillslope-scale numerical experiments, we find that landslides can occur not only in individual low strength areas but also across multiple smaller patches that coalesce. We show that reproducing observed size distributions requires spatial strength variations to be strongly localized, of large amplitude, and a consequence of multiple interacting factors. Such constraints can act together with the mechanical determinants of landslide initiation to produce size distributions of broadly similar character in widely different landscapes, as found in our examples. We propose that size distributions reflect the systematic scale dependence of the spatially averaged strength. Our results highlight the critical need to constrain the form, amplitude, and wavelength of spatial variability in material strength properties of hillslopes.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Chen, X. L., Q. Zhou, H. Ran et R. Dong. « Earthquake-triggered landslides in southwest China ». Natural Hazards and Earth System Sciences 12, n^o 2 (17 février 2012) : 351–63. http://dx.doi.org/10.5194/nhess-12-351-2012.

Texte intégral

Résumé :

Abstract. Southwest China is located in the southeastern margin of the Tibetan Plateau and it is a region of high seismic activity. Historically, strong earthquakes that occurred here usually generated lots of landslides and brought destructive damages. This paper introduces several earthquake-triggered landslide events in this region and describes their characteristics. Also, the historical data of earthquakes with a magnitude of 7.0 or greater, having occurred in this region, is collected and the relationship between the affected area of landslides and earthquake magnitude is analysed. Based on the study, it can be concluded that strong earthquakes, steep topography as well as fragile geological environment, are the main reasons responsible for serious landslides in southwest China. At the same time, it is found that the relationship between the area affected by landslides and the earthquake magnitude in this region are consistent with what has been obtained worldwide. Moreover, in this paper, it is seen that the size of the areas affected by landslides change enormously even under the same earthquake magnitude in the study region. While at the same tectonic place or fault belt, areas affected by landslides presented similar outline and size. This means that local geological conditions and historical earthquake background have an important influence on landslides distribution, and they should be considered when assessing earthquake-triggered landslide hazards at Grade 1 according to ISSMGE.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Qiu, Haijun, Peng Cui, Amar Deep Regmi, Sheng Hu, Yuzhu Zhang et Yi He. « Landslide distribution and size versus relative relief (Shaanxi Province, China) ». Bulletin of Engineering Geology and the Environment 77, n^o 4 (12 juillet 2017) : 1331–42. http://dx.doi.org/10.1007/s10064-017-1121-5.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

32

Chen, Lien-Kuang, Chih-Hsin Chang, Che-Hsin Liu et Jui-Yi Ho. « Application of a Three-Dimensional Deterministic Model to Assess Potential Landslides, a Case Study : Antong Hot Spring Area in Hualien, Taiwan ». Water 12, n^o 2 (11 février 2020) : 480. http://dx.doi.org/10.3390/w12020480.

Texte intégral

Résumé :

This study proposes a landslide disaster assessment model combining a fully three-dimensional, physically-based landslide model with high precision of in situ survey data such as surface slip signs, geologic drilling results, underground water observation, and displacement monitoring results over time to perform distribution of potential landslide zones and the size of landslides (area and volume) in the Antong hot spring area in Hualien, Taiwan. The distribution of potential landslide zones in the study area was represented by slope stability safety factors. The results of the analysis showed that the toe of the slope and two upward slopes in the study area were potential landslide areas with safety factors of 1.37, 0.92, and 1.19, respectively. The 3D model analysis results indicated that a landslide could occur at a depth of 20 m at the toe of the slope. Monitoring results for 2015 and 2016 showed that the sliding depth at the toe of the slope was approximately 22.5 m; consequently, the error of landslide depth was only 2.5 m. The simulated results and in situ monitoring results were in good agreement. In addition, the simulated landslide volume was also compared with the results of an empirical equation commonly used in Taiwan to determine their differences. The landslide volumes estimated using the empirical equation were only approximately 38.5% in zone 1, 42.9% in zone 2, and 21.7% in zone 3 of that generated by the proposed model. The empirical equation was used to calculate the landslide volume according to the landslide area, which was subsequently converted into landslide depth. However, the obtained landslide depth was considerably lower than that derived from the in situ monitoring, implying that an empirical estimation approach may result in serious underestimation. Thus, the proposed model could predict landslide area and volume in advance to assist authorities in minimizing loss of life and property damage during a heavy rainfall event.

Styles APA, Harvard, Vancouver, ISO, etc.

33

Wallace, Cory S., et Paul M. Santi. « Runout Number : A New Metric for Landslide Runout Characterization ». Environmental and Engineering Geoscience 27, n^o 4 (1 novembre 2021) : 455–70. http://dx.doi.org/10.2113/eeg-d-20-00144.

Texte intégral

Résumé :

ABSTRACT Landslide runout has traditionally been quantified by the height-to-length ratio, H/L, which, in many cases, is strongly influenced by the slope of the runout path. In this study, we propose an alternative mobility measure, the unitless Runout Number, measured as the landslide length divided by the square root of the landslide area, which characterizes landslide shape in terms of elongation. We used a database of 158 landslides of varying runout distances from locations in northern California, Oregon, and Washington state to compare the two runout measurement methods and explore their predictability using parameters that can be measured or estimated using geographic information systems. The Runout Number better describes the overall runout for several landslide and slope geometries. The two mobility measures show very little correlation to each other, indicating that the two parameters describe different landslide mobility mechanisms. When compared to predictive parameters shown by prior research to relate to landslide runout, the two runout measurement methods show different correlations. H/L correlates more strongly to initial slope angle, upslope contributing area, landslide area, and grain size distribution (percent clay, silt, total fines, and sand). The Runout Number correlates more strongly to planimetric curvature, upslope contributing area normalized by landslide area, and percent sand. Although these correlations are not necessarily strong enough for prediction, they indicate the validity of both runout measurement methods and the benefit of including both numbers when characterizing landslide mobility.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Yu, T. T., Y. S. Cheng, W. F. Peng et P. L. Lee. « ANALYSIS OF THE TEMPORAL AND SPATIAL CONTROLLING FACTORS IN AFFECTING THE ACCURACY OF LANDSLIDE PREDICTING MODEL AT TAIWAN ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W4 (6 mars 2018) : 579–82. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w4-579-2018.

Texte intégral

Résumé :

Abstract. Most of the landslides are triggered by rainfall, earthquake or the joint effect from both. Landslide inventory map by GIS via remote sensing offer the spatial distribution of it across certain external event. The landslide model thus been trained to link the occurrence and non-occurrence of individual mass wasting on top of proposing factors/layers. Chosen factors with various calculated weighting values becomes as the base of predicting the region and condition for future landslide called as Landslide Susceptibility Mapping (LSM). It is found that the temporal factor has less AUC values than spatial factors at Taiwan, after examining the 20 years catalog and thousand cases of landslide island wide. Different resolution of DEM and NDVI from satellite image, hyper spectrum and LiDAR are utilized to resolve the degree of impact of it. The require accuracy and resolution of base map is directly link to the accuracy and also minimum mapping size of catalog, and the non-linear relationship of external factors still cannot be well predicted by the training model. To achieve better accuracy of LSM the temporal and non-linearity properties should be addressed, especially under the influence of global warming.

Styles APA, Harvard, Vancouver, ISO, etc.

35

Glassmeyer, Michael P., et Abdul Shakoor. « Factors Contributing to Landslide Susceptibility of the Kope Formation, Cincinnati, Ohio ». Environmental and Engineering Geoscience 27, n^o 3 (11 mars 2021) : 307–18. http://dx.doi.org/10.2113/eeg-d-20-00077.

Texte intégral

Résumé :

ABSTRACT The objective of this study was to evaluate the factors that contribute to the high frequency of landslides in the Kope Formation and the overlying colluvial soil present in the Cincinnati area, southwestern Ohio. The Kope Formation consists of approximately 80 percent shale inter-bedded with 20 percent limestone. The colluvium that forms from the weathering of the shale bedrock consists of a low-plasticity clay. Based on field observations, LiDAR data, and information gathered from city and county agencies, we created a landslide inventory map for the Cincinnati area, identifying 842 landslides. From the inventory map, we selected 10 landslides that included seven rotational and three translational slides for detailed investigations. Representative samples were collected from the landslide sites for determining natural water content, Atterberg limits, grain size distribution, shear strength parameters, and slake durability index. For the translational landslides, strength parameters were determined along the contact between the bedrock and the overlying colluvium. The results of the study indicate that multiple factors contribute to landslide susceptibility of the Kope Formation and the overlying colluvium, including low shear strength of the colluvial soil, development of porewater pressure within the slope, human activity such as loading the top or cutting the toe of a slope, low to very low durability of the bedrock that allows rapid disintegration of the bedrock and accumulation of colluvial soil, undercutting of the slope toe by stream water, and steepness of the slopes.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Shen, Yong Jiang, Hai Hao Cui, Biao Deng et Wen Kang. « Optimization Design of Coupling Beam of the Frame Double-Row Piles ». Applied Mechanics and Materials 353-356 (août 2013) : 918–23. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.918.

Texte intégral

Résumé :

Double-row piles are often used for the large-scale landslide control. The frame double-row piles are the common types. Coupling beam is an important component of frame double-row piles. It plays an important role in transferring landslide thrust. A finite element model of landslide was established to evaluate the effect of section size and length of coupling beam on the internal force of double-row piles. It was found that the internal force of double-row piles increased with the length of coupling beam, and found that it was unfavorable for the moment distribution of double-row piles if the section size of coupling beam was too large or small. Therefore, the reasonable length of coupling beam is equal to the height of the piles section. With the reasonable moment distribution of double-row piles, the section size of coupling beam has an optimum value.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Maki Mateso, Jean-Claude, Charles L. Bielders, Elise Monsieurs, Arthur Depicker, Benoît Smets, Théophile Tambala, Luc Bagalwa Mateso et Olivier Dewitte. « Characteristics and causes of natural and human-induced landslides in a tropical mountainous region : the rift flank west of Lake Kivu (Democratic Republic of the Congo) ». Natural Hazards and Earth System Sciences 23, n^o 2 (10 février 2023) : 643–66. http://dx.doi.org/10.5194/nhess-23-643-2023.

Texte intégral

Résumé :

Abstract. Tropical mountainous regions are often identified as landslide hotspots with growing population pressure. Anthropogenic factors are assumed to play a role in the occurrence of landslides in these densely populated regions, yet the relative importance of these human-induced factors remains poorly documented. In this work, we aim to explore the impact of forest cover dynamics, roads and mining activities on the characteristics and causes of landslides in the rift flank west of Lake Kivu in the Democratic Republic of the Congo (DR Congo). To do so, we compile a comprehensive multi-temporal inventory of 2730 landslides. The landslides are of different types and are grouped into five categories that are adapted to study the impact of human activities on slope stability: old (pre-1950s) and recent (post-1950s) deep-seated landslides, shallow landslides, landslides associated with mining and landslides associated with road construction. We analyse the landslides according to this classification protocol via frequency–area statistics, frequency ratio distribution and logistic regression susceptibility assessment. We find that natural factors contributing to the cause of recent and old deep-seated landslides were either different or changed over time. Under similar topographic conditions, shallow landslides are more frequent, but of a smaller size, in areas where deforestation has occurred since the 1950s. We attribute this size reduction to the decrease in regolith cohesion due to forest loss, which allows for a smaller minimum critical area for landsliding. In areas that were already deforested in the 1950s, shallow landslides are less frequent, larger and occur on less steep slopes. This suggests a combined role between regolith availability and soil management practices that influence erosion and water infiltration. Mining activities increase the odds of landsliding. Landslides associated with mining and roads are larger than shallow landslides but smaller than the recent deep-seated instabilities, and they are controlled by environmental factors that are not present under natural conditions. Our analysis demonstrates the role of human activities on the occurrence of landslides in the Lake Kivu region. Overall, it highlights the need to consider this context when studying hillslope instability characteristics and distribution patterns in regions under anthropogenic pressure. Our work also highlights the importance of using landslide classification criteria adapted to the context of the Anthropocene.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Dellow, Sally, Chris Massey, Simon Cox, Garth Archibald, John Begg, Zane Bruce, Jon Carey et al. « Landslides caused by the Mw7.8 Kaikōura earthquake and the immediate response ». Bulletin of the New Zealand Society for Earthquake Engineering 50, n^o 2 (30 juin 2017) : 106–16. http://dx.doi.org/10.5459/bnzsee.50.2.106-116.

Texte intégral

Résumé :

Tens of thousands of landslides were generated over 10,000 km2 of North Canterbury and Marlborough as a consequence of the 14 November 2016, Mw7.8 Kaikōura Earthquake. The most intense landslide damage was concentrated in 3500 km2 around the areas of fault rupture. Given the sparsely populated area affected by landslides, only a few homes were impacted and there were no recorded deaths due to landslides. Landslides caused major disruption with all road and rail links with Kaikōura being severed. The landslides affecting State Highway 1 (the main road link in the South Island of New Zealand) and the South Island main trunk railway extended from Ward in Marlborough all the way to the south of Oaro in North Canterbury. The majority of landslides occurred in two geological and geotechnically distinct materials reflective of the dominant rock types in the affected area. In the Neogene sedimentary rocks (sandstones, limestones and siltstones) of the Hurunui District, North Canterbury and around Cape Campbell in Marlborough, first-time and reactivated rock-slides and rock-block slides were the dominant landslide type. These rocks also tend to have rock material strength values in the range of 5-20 MPa. In the Torlesse ‘basement’ rocks (greywacke sandstones and argillite) of the Kaikōura Ranges, first-time rock and debris avalanches were the dominant landslide type. These rocks tend to have material strength values in the range of 20-50 MPa. A feature of this earthquake is the large number (more than 200) of valley blocking landslides it generated. This was partly due to the steep and confined slopes in the area and the widely distributed strong ground shaking. The largest landslide dam has an approximate volume of 12(±2) M m3 and the debris from this travelled about 2.7 km2 downslope where it formed a dam blocking the Hapuku River. The long-term stability of cracked slopes and landslide dams from future strong earthquakes and large rainstorms are an ongoing concern to central and local government agencies responsible for rebuilding homes and infrastructure. A particular concern is the potential for debris floods to affect downstream assets and infrastructure should some of the landslide dams breach catastrophically. At least twenty-one faults ruptured to the ground surface or sea floor, with these surface ruptures extending from the Emu Plain in North Canterbury to offshore of Cape Campbell in Marlborough. The mapped landslide distribution reflects the complexity of the earthquake rupture. Landslides are distributed across a broad area of intense ground shaking reflective of the elongate area affected by fault rupture, and are not clustered around the earthquake epicentre. The largest landslides triggered by the earthquake are located either on or adjacent to faults that ruptured to the ground surface. Surface faults may provide a plane of weakness or hydrological discontinuity and adversely oriented surface faults may be indicative of the location of future large landslides. Their location appears to have a strong structural geological control. Initial results from our landslide investigations suggest predictive models relying only on ground-shaking estimates underestimate the number and size of the largest landslides that occurred.

Styles APA, Harvard, Vancouver, ISO, etc.

39

Wu, C. Y., et S. C. Chen. « Integrating spatial and temporal probabilities for the annual landslide hazard maps in Shihmen watershed, Taiwan ». Natural Hazards and Earth System Sciences Discussions 1, n^o 2 (19 mars 2013) : 471–508. http://dx.doi.org/10.5194/nhessd-1-471-2013.

Texte intégral

Résumé :

Abstract. Landslide spatial probability, temporal probability, and landslide size probability were employed to perform landslide hazard assessment in this study. Following a screening process, landslide susceptibility-related factors included eleven intrinsic geomorphological factors and two extrinsic rainfall factors, which were evaluated as effective factors because of the higher correlation with the landslide distribution. Landslide area analysis was first employed to establish the power law relationship between landslide area and noncumulative number, and a probability density function was then used to convert this relationship to cumulative probability of landslide area. The exceedance probability of rainfall with different recurrence intervals was used to determine the temporal probability of those events. Finally, the landslide spatial probability, landslide area probability, and exceedance probability were integrated to estimate the annual probability of each slope-unit with a landslide area exceeding a certain threshold in a watershed. The slope-units with high landslide probability were concentrated in Taigang River watershed, which should be the leading target of future management efforts.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Havenith, Hans-Balder, Kelly Guerrier, Romy Schlögel, Anika Braun, Sophia Ulysse, Anne-Sophie Mreyen, Karl-Henry Victor et al. « Earthquake-induced landslides in Haiti : analysis of seismotectonic and possible climatic influences ». Natural Hazards and Earth System Sciences 22, n^o 10 (18 octobre 2022) : 3361–84. http://dx.doi.org/10.5194/nhess-22-3361-2022.

Texte intégral

Résumé :

Abstract. First analyses of landslide distribution and triggering factors are presented for the region affected by the 14 August 2021 earthquake (Mw=7.2) in the Nippes Department, Haiti. Landslide mapping was mainly carried out by comparing pre- and post-event remote imagery (∼0.5–1 m resolution) available on Google Earth Pro® and Sentinel-2 (10 m resolution) satellite images. The first covered about 50 % of the affected region (for post-event imagery and before completion of the map in January 2022), and the latter were selected to cover the entire potentially affected zone. On the basis of the completed landslide inventory, comparisons are made with catalogs compiled by others both for the August 2021 and the January 2010 seismic events, including one open inventory (by the United States Geological Survey) that was also used for further statistical analyses. Additionally, we studied the pre-2021 earthquake slope stability conditions. These comparisons show that the total number of landslides mapped for the 2021 earthquake (7091) is larger than the one recently published by another research team for the same event but slightly smaller than the number of landslides mapped by a third research team. It is also clearly smaller than the one observed by two other research teams for the 2010 earthquake (e.g., 23 567, for the open inventory). However, these apparently fewer landslides triggered in 2021 cover much wider areas of slopes (>80 km2) than those induced by the 2010 event (∼25 km2 – considering the open inventory). A simple statistical analysis indicates that the lower number of 2021 landslides can be explained by the missing detection of the smallest landslides triggered in 2021, partly due to the lower-resolution imagery available for most of the areas affected by the recent earthquake; this is also confirmed by an inventory completeness analysis based on size–frequency statistics. The much larger total area of landslides triggered in 2021, compared to the 2010 earthquake, can be related to different physical reasons: (a) the larger earthquake magnitude in 2021, (b) the more central location of the fault segment that ruptured in 2021 with respect to coastal zones, (c) and possible climatic preconditioning of slope instability in the 2021 affected area. These observations are supported by (1) a new pre-2021 earthquake landslide map; (2) rainfall distribution maps presented for different periods (including October 2016 – when Hurricane Matthew had crossed the western part of Haiti), covering both the 2010 and 2021 affected zones; and (3) shaking intensity prediction maps.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Jibson, Randall W. « Types and Areal Distribution of Ground Failure Associated with the 2019 Ridgecrest, California, Earthquake Sequence ». Bulletin of the Seismological Society of America 110, n^o 4 (5 mai 2020) : 1567–78. http://dx.doi.org/10.1785/0120200001.

Texte intégral

Résumé :

ABSTRACT The July 2019 Ridgecrest, California, earthquake sequence included the largest earthquake (M 7.1) to strike the conterminous United States in the past 20 yr. To characterize the types, numbers, and areal distributions of different types of ground failure (landslides, liquefaction, and ground cracking), I conducted a field investigation of ground failure triggered by the sequence around the periphery of the epicentral area (which had limited access). The earthquake sequence triggered sparse and widely scattered landslides over an area of ∼22,000 km2 and at a maximum epicentral distance of 114 km; these metrics are within the upper bounds as compared with global averages for earthquakes of similar size. Some rock falls blocked primary and secondary roads, but no other landslide damage was reported. Almost all of the landslides in the peripheral area were small rock falls (∼1–10 m3), but a few larger (∼100 m3) rock slides also occurred. Though there are only informal reports about ground failure in the immediate epicentral area and we lack a detailed survey there, the small number (hundreds) and size of the landslides still seems to be far below global averages for M 7.1. This could be a result of the arid landscape and lack of a deeply weathered zone of soil and regolith. Liquefaction occurred along part of the western margin of Searles Valley. One large (∼0.4 km2) lateral spread caused by liquefaction severely damaged parts of Trona. Minor liquefaction also occurred in a ∼100-m-wide band along the fault-rupture zone in some places.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Iwahashi, Junko, Shiaki Watanabe et Takahiko Furuya. « Mean slope-angle frequency distribution and size frequency distribution of landslide masses in Higashikubiki area, Japan ». Geomorphology 50, n^o 4 (mars 2003) : 349–64. http://dx.doi.org/10.1016/s0169-555x(02)00222-2.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

43

Krzeminska, D. M., T. A. Bogaard, Th W. J. van Asch et L. P. H. van Beek. « A conceptual model of the hydrological influence of fissures on landslide activity ». Hydrology and Earth System Sciences 16, n^o 6 (1 juin 2012) : 1561–76. http://dx.doi.org/10.5194/hess-16-1561-2012.

Texte intégral

Résumé :

Abstract. Hydrological processes control the behaviour of many unstable slopes, and their importance for landslide activity is generally accepted. The presence of fissures influences the storage capacity of a soil and affects the infiltration processes of rainfall. The effectiveness of the fissure network depends upon fissure size, their spatial distribution, and connectivity. Moreover, fissure connectivity is a dynamic characteristic, depending on the degree of saturation of the medium. This research aims to investigate the influence of the fissure network on hydrological responses of a landslide. Special attention is given to spatial and temporal variations in fissure connectivity, which makes fissures act both as preferential flow paths for deep infiltration (disconnected fissures) and as lateral groundwater drains (connected fissures). To this end, the hydrological processes that control the exchange of water between the fissure network and the matrix have been included in a spatially distributed hydrological and slope stability model. The ensuing feedbacks in landslide hydrology were explored by running the model with one year of meteorological forcing. The effect of dynamic fissure connectivity was evaluated by comparing simulations with static fissure patterns to simulations in which these patterns change as a function of soil saturation. The results highlight that fissure connectivity and fissure permeability control the water distribution within landslides. Making the fissure connectivity function of soil moisture results in composite behaviour spanning the above end members and introduces stronger seasonality of the hydrological responses.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Chunga, Kervin, Franz A. Livio, Carlos Martillo, Hernán Lara-Saavedra, Maria Francesca Ferrario, Ivan Zevallos et Alessandro Maria Michetti. « Landslides Triggered by the 2016 Mw 7.8 Pedernales, Ecuador Earthquake : Correlations with ESI-07 Intensity, Lithology, Slope and PGA-h ». Geosciences 9, n^o 9 (26 août 2019) : 371. http://dx.doi.org/10.3390/geosciences9090371.

Texte intégral

Résumé :

We provide a dataset of the landslides induced by the 2016 Pedernales megathrust earthquake, Ecuador (Mw 7.8, focal depth of 20 km) and compare their spatial distribution with mapped bedrock lithology, horizontal peak ground acceleration (PGA-h) and the macroseismic intensity based on earthquake-induced environmental effects (ESI-07). We studied 192 coseismic landslides (classified as coherent, disrupted and lateral spreads) located in the epicentral area, defined by the VII to IXESI-07 isoseismals. Based on our findings, lahar deposits, tuffs and volcanoclastic units are the most susceptible to landslides occurrence. Alluvial plains with fluvial loose fine sand are the most susceptible setting for lateral spreading, with a maximum intensity of IXESI-07. The coherent landslides are frequently found in altered shale and siltstone geological units with moderate slopes (8°–16°), with typical intensity ranging between VII and VIIIESI-07. Our analysis draws a typical framework for slope movements triggered by subduction earthquakes in Ecuador. The most dangerous setting is the coastal region, a relatively highly urbanized area located near the epicenter and where liquefaction can trigger massive lateral spreading events. Coherent and disrupted landslides, dominating the more internal hilly region, can be triggered also in moderate slope settings (i.e., less than 10°). Indeed, the regression analysis between seismic intensity, PGA-h and landslide occurrence shows that most of the events occurred at PGA-h values between 0.4 g and 1.2 g, at a distance of 30 to 50 km from the rupture plane. Our database suggests that lithology and hillslope geometry are the main geological/geomorphological factors controlling coseismic landslides occurrence; while the distance from the rupture plane plays a significant role on determining the landslide size. Finally, we underline that coseismically-triggered landslides are among the most common environmental effects occurring during large subduction events that can be effectively used to properly evaluate the earthquake macroseismic field. The landslide inventory we compiled is suitable for assessing the vulnerability of physical environment from subduction earthquakes in Ecuador, and offers a primary data source for future worldwide analysis.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Guthrie, R. H., et S. G. Evans. « Magnitude and frequency of landslides triggered by a storm event, Loughborough Inlet, British Columbia ». Natural Hazards and Earth System Sciences 4, n^o 3 (4 août 2004) : 475–83. http://dx.doi.org/10.5194/nhess-4-475-2004.

Texte intégral

Résumé :

Abstract. One hundred and one landslides were documented across 370km2 following a rainstorm that swept the British Columbia coastline on 18 November 2001. Despite the regional nature of the storm, the landslides were spaced close together, even within the study area. Landslide clustering is attributed to high intensity storm cells too small to be recorded by the general hydrometric network. The evidence nicely corroborates previous historical studies that reached similar conclusions, but against which there was no modern analog analyzed for coastal British Columbia. Magnitude-cumulative frequency data plotted well on a power law curve for landslides greater than 10000m2, however, below that size several curves would fit. The rollover effect, a point where the data is no longer represented by the power law, therefore occurs at about 1.5 orders of magnitude higher than the smallest landslide. Additional work on Vancouver Island has provided evidence for rollovers at similar values. We propose that the rollover is a manifestation of the physical conditions of landslide occurrence and process uniformity. The data was fit to a double Pareto distribution and P-P plots were generated for several data sets to examine the fit of that model. The double Pareto model describes the bulk of the data well, however, less well at the tails. For small landslides (<650m2) this may still be a product of censoring. Landscape denudation from the storm was averaged over the study area and equal to 2mm of erosion. This is more than an order of magnitude larger than the annual rate of denudation reported by other authors for coastal British Columbia, but substantially less than New Zealand. The number is somewhat affected by the rather arbitrary choice of a study area boundary.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Daxer, Christoph, Maddalena Sammartini, Ariana Molenaar, Thomas Piechl, Michael Strasser et Jasper Moernaut. « Morphology and spatio-temporal distribution of lacustrine mass-transport deposits in Wörthersee, Eastern Alps, Austria ». Geological Society, London, Special Publications 500, n^o 1 (19 décembre 2019) : 235–54. http://dx.doi.org/10.1144/sp500-2019-179.

Texte intégral

Résumé :

AbstractIn lakes, landslides can be studied in high resolution due to their accessibility and limited size. Here, we investigate mass-transport deposits in glacigenic Wörthersee (Eastern European Alps) by integration of seismic, sediment core and multibeam bathymetric data. Two outstanding landslide events were revealed: the first occurred in the Late Glacial, leading to multiple deposits of up to 15 m thickness; they consist of sandy turbidites and mudclast conglomerates, which are overlain by a 2.5 m thick megaturbidite. The extensive, likely earthquake-triggered failure linked to this event was preconditioned by rapid sedimentation of fine-grained glaciolacustrine sediments and associated build-up of excess pore pressure. The second event was presumably triggered by a major earthquake (Mw≈7) in AD 1348 and comprises a mass-transport complex and several landslides, which led to a c. 30 cm thick turbidite. In total, 62 landslides are imaged in the multibeam map, 6 of which are most likely human-induced. Some of these show horseshoe-type compressional ridges and frontal breaching, whereas others exhibit an extensive zone of rafted blocks. We attribute these morphological differences to four main factors: (1) slope gradient and changes therein; (2) preconditioning of the impacted zone; (3) volume of remobilized sediment; and (4) type of impactor.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Gariano, S. L., O. Petrucci et F. Guzzetti. « Changes in the occurrence of rainfall-induced landslides in Calabria, Southern Italy, in the 20th century ». Natural Hazards and Earth System Sciences Discussions 3, n^o 6 (4 juin 2015) : 3579–619. http://dx.doi.org/10.5194/nhessd-3-3579-2015.

Texte intégral

Résumé :

Abstract. We exploit a catalogue of 1466 rainfall events with landslides in the 90 year period 1921–2010 to study temporal and geographical variations in the occurrence of landslides in Calabria, Southern Italy. We use daily rainfall records obtained by a network of 318 rain gauges to reconstruct 448 493 rainfall events. Combining the rainfall and the landslide information, we obtain a catalogue of 1466 rainfall events with landslides (REL) in Calabria from 1921 to 2010, where a REL is the occurrence of one or more landslide during or immediately after a rainfall event. We find that the geographical and the temporal distributions of the rainfall-induced landslides have changed in the observation period. The average and the maximum values of the cumulated event rainfall that have resulted in landslides in the recent-most 30 year period 1981–2010 are lower than the values necessary to trigger landslides in previous periods, whereas the duration of the rainfall events that triggered landslides has remained the same. This can be considered evidence of variations in rainfall conditions, but also an increase in the vulnerability of the territory. We further find that the yearly distribution of rainfall-induced landslides has changed in the observation period, analysing the variations in the number of rainfall events with landslides occurred in each month in three 30 year periods. To investigate variations in the impact of REL on the population, we compared the number of REL in each of the 409 municipalities in Calabria, with the size of the population in the municipalities, measured by national Censuses conducted in 1951, 1981, and 2011. For the purpose, we adopted two strategies. The first strategy considered impact as IREL = #REL/P and the second strategy measured impact as RREL = #REL × P, where #REL is the total number of REL in a period, and P is the size of the population in the same period and geographical area. Considering the entire observation period, IREL and RREL have both increased in Calabria. However, considering the changes between the recent period 1981–2010 and the previous period 1951–1980, results are more variegated with a number of municipalities where IREL and RREL have increased, or decreased. Municipalities where IREL has increased are mainly in the mountains, and municipalities where RREL has increased are mainly along the coasts.

Styles APA, Harvard, Vancouver, ISO, etc.

48

Tessema, Netsanet Nigatu, Fjóla G. Sigtryggsdóttir, Leif Lia et Asie Kemal Jabir. « Case Study of Dam Overtopping from Waves Generated by Landslides Impinging Perpendicular to a Reservoir’s Longitudinal Axis ». Journal of Marine Science and Engineering 7, n^o 7 (15 juillet 2019) : 221. http://dx.doi.org/10.3390/jmse7070221.

Texte intégral

Résumé :

Landslide-generated impulse waves in dammed reservoirs run up the reservoir banks as well as the upstream dam slope. If large enough, the waves may overtop and even breach the dam and cause flooding of the downstream area with hazardous consequences. Hence, for reservoirs in landslide-prone areas, it is important to provide a means to estimate the potential size of an event triggered by landslides along the reservoir banks. This research deals with landslide-generated waves and the overtopping process over the dam crest in a three-dimensional (3D) physical model test, presenting a case study. The model set-up describes the landslide impacting the reservoir in a perpendicular manner, which is often the case in natural settings. Based on the experimental results, dimensionless empirical relations are derived between the overtopping volume and the governing parameters, namely the slide volume, slide release height, slide impact velocity, still-water depth, and upstream dam face slope. Predictive relations for the overtopping volume are presented as applicable for cases relating to the specific model set-up. Measured overtopping volumes are further compared to a two-dimensional (2D) case reported in the literature. An important feature regarding the overtopping process for the 3D case is the variation in time and space, resulting in an uneven distribution of the volume of water overtopping the dam crest. This observation is made possible by the 3D model set-up, and is of value for dam safety considerations as well as for foundation-related issues, including erosion and scouring.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Harianto, T., A. B. Muhiddin, S. H. Nur et C. E. Wibowo. « Properties of debris flow deposits in Masamba, South Sulawesi, Indonesia ». IOP Conference Series : Earth and Environmental Science 921, n^o 1 (1 novembre 2021) : 012062. http://dx.doi.org/10.1088/1755-1315/921/1/012062.

Texte intégral

Résumé :

Abstract On 13 July 2020, a huge landslide-induced debris flow struck Masamba city and its vicinity, providing a massive amount of sedimentation materials. The landslide-induced debris flow was triggered by heavy rainfall, causing damages such as life and property losses, traffic disruption. Landslide-induced debris flow is a sudden natural hazard in mountain regions characterized by fast velocity, huge impact area, large scale, and often causes disastrous accidents. This study aims to investigate the properties of the debris flow materials including the soil size distribution, density, shear strength and bearing capacity. The results showed that the sedimentation material at landslide sites containing a large amount of sand which is classified as a poorly graded sand (SP). The engineering properties such as density, cohesion, internal friction angle and the value California Bearing Ratio (CBR) were also discussed.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Oktaviani, Revia, Paulus P. Rahardjo et Imam A. Sadisun. « Landslides induced by slaking of geomaterial ». MATEC Web of Conferences 229 (2018) : 03011. http://dx.doi.org/10.1051/matecconf/201822903011.

Texte intégral

Résumé :

The geological event that happens because of an unbalance between shear strength and shear stress on rock mass is known as a landslide. This usually occurs due to improper handling of the exposed material. The landslide occurs because of the reaction to reduce the burden it bears so that the mass of the rock will move rock mass from the higher elevation to lower elevation. Many landslides, in west java, Indonesia occurred on exposed clay shale that is protected by soldier pile with 3m in distance between pile. On top of the clay shale, there is a building which gives an additional load on the clay shale. To determine the effect of water and temperature on clay shale, static slaking index test was conducted. With a submerge variation, it was found that the slaking index value ranged from 2.17% to 12.0% with the slaking classification from very low to medium. The size distribution was produced from 1/4 and 1/2 sample submerge show bigger rock breakage than rock with 3/4 sample submerge and sample fully submerge. Observations of the sample in room temperature without contact of water and no additional mass were also done. The sample was still intact until the end of research work.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Landslide Size Distribution »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres