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1.
The dynamic interaction of endogenic and exogenic processes in active geodynamic context leads to the deterioration of the physico-mechanical characteristics of the rocks, inducing slopes instability. In such context, the morphometric parameters and the analysis of landslide distribution contribute to appraise the evolutive state of hydrographic basins. The aim of the study is the morphometric characterization of the Roccella Torrent basin (Rtb) located in South Italy. Landsliding and tectonic structure dynamically interact with the drainage pattern that records these effects and permits the definition of the evolutive geomorphic stage of the basin. The Air Photograph Investigation and field surveys permitted to draw the main geomorphic features, the drainage pattern of the Rtb, to calculate the morphometric parameters and to delimit the landslides’ bodies. Detailed analysis about the landslide distribution within a test site 17 km2 wide were carried out to elaborate indicative indexes of the landslides type and to single out the lithotypes that are more involved in slope instability phenomena. The morphometric parameters indicate the rejuvenation state within the Rtb where the stream reaches show the effects of increased energy relief in agreement with the geological settings of this sector of the Apennine–Maghrebian Chain.  相似文献   

2.
Kat County, which is located in a slope of hilly region and constructed in the side of a mountain along the North Anatolian Fault Zone, is frequently subject to landslides. The slides occur during periods of heavy rainfall, and these events cause destruction to property, roads, agricultural lands and buildings. In the last few decades, a lot of houses and buildings have been damaged and destroyed. Settlement areas have remained evacuated for a long time. The slope instabilities in the study area are a complex landslide extending from north to south containing a lot of landslides. Field investigations, interpretation of aerial photography, analyses of geological data and laboratory tests suggest that some factors have acted together on the slopes to cause the sliding. In the wet season, the slopes became saturated. As the saturation of the earth material on the slope causesa rise in water pressure, the shear strength (resisting forces) decreases and the weight (driving forces) increases; thus, the net effect was to lower the safety factor. Previous failures have affected the rock mass, leading to the presence of already sheared surfaces at residual strengths. The relation between the joint planes and the instability of the slope in the study area was discussed and it was found that the potential slope instabilities are mainly in the directions of NW–SE, NE–SW and N–S. The landslide susceptibility map obtained by using the geographical information system showed that a large area is susceptible and prone to landslides in the northern part of the study area.An erratum to this article can be found at  相似文献   

3.
天水市“7.25”群发性山洪地质灾害发育特征及成因分析   总被引：4，自引：0，他引：4  
通过对天水市"7.25"群发性山洪地质灾害的现场调查,系统查明了此次地质灾害的灾情、致灾因素、灾害特征、致灾范围以及分布规律,分析了此次山洪地质灾害发育特征及成因。结果表明:本次由强降雨引发并加剧的地质灾害类型主要以黄土-泥岩及黄土滑坡为主,中小型沟谷泥石流、土质崩塌和土质不稳定斜坡次之。"7.25"山洪地质灾害具有普遍性、群发性、局地爆发性等特征,其隐蔽性强,潜在危害大,灾害链模式显著。灾害发生期间降雨具有强度大、范围广等特点,使区内山体岩土体饱和,显著降低了岩土体抗剪强度,加之与地震的叠加效应明显加剧了此次群发性山洪地质灾害。  相似文献   

4.
This study aims at contributing to the soil slip susceptibility assessment in a typical basin of the southern Apuan Alps, Italy. On June 1996, this basin (Cardoso Torrent, 13 km2 large) was hit by an extremely heavy rainstorm (maximum intensity of about 160 mm/h), which caused many landslides (debris slide–debris flows) and valley bottom flows (hyperconcentrated flows), destruction and deaths. Detailed surveys provided the characterization of the main factors (geological, geomorphologic, hydrological, hydrogeological and geotechnical) which contributed in triggering landslides. In order to evaluate the soil slip susceptibility in this area, a physically based model was applied and a GIS analysis of digital elevation model was performed. This approach couples a mechanical model based on an infinite slope form of the Mohr–Coulomb failure criterion, and a steady-state hydrological one (a modified version of Shalstab, which considers the cohesion of the debris material potentially involved in landsliding). GIS techniques allowed evaluating the effects of topographic convergence and drainage area on slope failure. In this way, based on the infiltration rate, the triggering of the June 1996 landslides was simulated and the critical rainfall thresholds assessed at about 200–250 mm/24 h.  相似文献   

5.
汶川地震极重灾区地质背景及次生斜坡灾害空间发育规律   总被引：22，自引：4，他引：18  
512汶川大地震造成大量的次生斜坡灾害,本次研究区域为汶川大地震的11个重灾区,包括汶川、北川、青川、安县、平武、茂县、江油、彭州、什邡、绵竹、理县等市县。通过对重灾区航片、卫片、雷达图像的解译研究发现,重灾区次生斜坡灾害的主要灾种表现为崩塌、滑坡以及崩塌、滑坡高速运动解体形成的碎屑流（个别地方由于水的参与表现为泥石流）以及它们堵江形成的堰塞湖。研究发现地震次生斜坡灾害的发育具有明显的丛集性规律。从区域上看,次生斜坡灾害明显呈带状,沿龙门山断裂带展布,并主要受北川映秀断裂控制。各灾种的发育在不同地段发育的规模、频率差别较大。以灾害分布面积来排序,汶川县灾害面积最大,为131.55km2,其次为北川县,为45.57km2,其余9个县（市）灾害面积相差不大,均介于6~17km2,其中理县灾害面积最小,为6.25km2。各灾种的发育在不同地段发育的规模、频率差别较大。青川县、平武县灾种主要为滑坡,汶川县、茂县、安县、理县灾种主要表现崩塌转化的碎屑流,北川的主要灾种则为碎屑流,其次为滑坡,什邡、彭州、绵竹、江油等地主要灾种为崩塌。 灾种发育的这种地域性差别主要受控于地层岩性,除此而外,还与构造特征、地形地貌等因素紧密相关。研究表明:岩性对灾害种类的展布有决定性控制作用。统计发现,岩性越坚硬,崩塌、碎屑流发育率越高,滑坡则在软岩地区、较软岩地区和较坚硬区发育率最高,泥石流则在软岩地区最为发育。地形地貌对次生斜坡灾害的发育有重要影响,统计表明,崩塌、碎屑流以及泥石流在1200～2000m坡段范围内发育率最高,其次为800～1200m坡段;而滑坡则在800～1200m坡段范围发育率最高。对坡度而言,除11~20坡度范围外,崩塌和碎屑流的发育率总体具有随坡度增高而增大的特点;而滑坡和泥石流的发育率呈现典型的单峰特征,在1~20范围内发育率最大。坡向对地震次生斜坡灾害的发育影响不明显。 地震次生斜坡灾害的发育规律表明,地震斜坡灾害的发生主要受控于活动构造本身,并沿活动构造呈带状展布,同时受场地条件如岩性、地形地貌等因素的强烈控制。  相似文献   

6.
The present study was conducted along the Mugling–Narayanghat road section and its surrounding region that is most affected by landslide and related mass-movement phenomena. The main rock types in the study area are limestone, dolomite, slate, phyllite, quartzite and amphibolites of Lesser Himalaya, sandstone, mudstone and conglomerates of Siwaliks and Holocene Deposits. Due to the important role of geology and rock weathering in the instabilities, an attempt has been made to understand the relationship between these phenomena. Consequently, landslides of the road section and its surrounding region have been assessed using remote sensing, Geographical information systems and multiple field visits. A landslide inventory map was prepared and comprising 275 landslides. Nine landslides representing the whole area were selected for detailed studies. Field surveys, integrated with laboratory tests, were used as the main criteria for determining the weathering zones in the landslide area. From the overall study, it is seen that large and complex landslides are related to deep rock weathering followed by the intervention of geological structures as faults, joints and fractures. Rotational types of landslides are observed in highly weathered rocks, where the dip direction of the foliation plane together with the rock weathering plays a principle role. Shallow landslides are developed in the slope covered by residual soil or colluviums. The rock is rather fresh below these covers. Some shallow landslides (rock topples) are related to the attitude of the foliation plane and are generally observed in fresh rocks. Debris slides and debris flows occur in colluviums or residual soil-covered slopes. In few instances, they are also related to the rock fall occurring at higher slopes. The materials from the rock fall are mixed with the colluviums and other materials lying on the slope downhill and flow as debris flow. Rock falls are mainly related to the joint pattern and the slope angle. They are found in less-weathered rocks. From all these, it is concluded that the rock weathering followed by geological structures has prominent role in the rock slope instability along Mugling–Narayanghat road section and its surrounding regions.  相似文献   

7.
. Recently, numerous landslides occurred in the northern part of Koyulhisar. In 1998 and 2000, which were very wet years, landslides in different masses affected the geological formations which are well known for being prone to slope movements. Detailed geological, geomorphological and geotechnical surveys were carried out, and stability conditions in Koyulhisar village, located NE of Sivas (Turkey), are discussed in this paper. Kinematical analyses showed that the potential slope instabilities are in two main directions: the first direction is SE and the second is SW, these directions corresponding to the dominant slope directions of the study area. Geomechanic surveys confirmed that most of the rock slopes analysed are highly prone to instability. The SMR criterion gave results which correspond well with real stability conditions. Jointing and faulting, steep topography, water incisions, and heavy rainfall played a significant role in the occurrence of the landslides.  相似文献   

8.
映秀—卧龙公路沿线汶川地震地质灾害研究   总被引：4，自引：0，他引：4  
映秀—卧龙公路是汶川地震灾区距震中最近、震害最为严重的一条公路,本文对沿线地震地质灾害进行了详细的调查研究。依据震害特征,将沿线震害划分为斜坡中上部强风化岩体及土层失稳、结构面切割岩体崩滑失稳、滑坡、泥石流等4类,并分析了沿线震害发育规律。调查表明:龙门山后山断裂两侧地震地质灾害呈现显著的差异性,主要是由深大断裂的消震隔震效应,地貌放大效应,地质结构等三方面因素决定的。通过134条实测剖面分析,研究了地震失稳斜坡坡度和失稳部位。地震诱发失稳斜坡坡度在33°~84°之间,主要分布在41°~65°之间,可以认为地震诱发斜坡失稳灾害主要发生在40°以上的斜坡。斜坡失稳部位主要分布在斜坡中上部以及地貌突出部位,主要失稳部位在0.4坡高以上。从研究斜坡动力失稳的角度,将沿线斜坡划分为基岩-土层及强风化层斜坡地质结构、不利外倾结构面基岩斜坡地质结构、块状构造基岩斜坡地质结构、块碎石土层斜坡地质结构等几种地质结构模型,分析论述了各种地质结构相应的地震地质灾害类型及特点。  相似文献   

9.
Detailed geomorphological mapping carried out in 5 sample areas in the North of Lisbon Region allowed us to collect a set of geological and geomorphological data and to correlate them with the spatial occurrence of landslide. A total of 597 slope movements were identified in a total area of 61.7 km2, which represents about 10 landslides per km2.The main landslide conditioning factors are: lithology and geological structure, slope angle and slope morphology, land use, presence of old landslides, and human activity.The highest landslide density occurs in Cretaceous marls and marly limestones, but the largest movements are in Jurassic clays, marls and limestones.The landslide density is higher on slopes with gradients above 20 °, but the largest unstable area is found on slopes of 10 ° to 15 °, thus reflecting the presence of the biggest slope movements. There is a correlation between landslides and topographical concavities, a fact that can be interpreted as reflecting the significance of the hydrological regime in slope instability.Concerning land use, the highest density of landslides is found on slopes covered with shrub and undergrowth vegetation.About 26% of the total number of landslides are reactivation events. The presence of old landslides is particularly important in the occurrence of translational slides and complex and composite slope movements.20% of the landslide events were conditioned by anthropomorphic activity. Human's intervention manifests itself in ill-consolidated fills, cuts in potentially unstable slopes and, in a few cases, in the changing of river channels.Most slope movements in the study area exhibit a clear climatic signal. The analysis of rainfall distribution in periods of recognised slope instability allows the distinction of three situations: 1) moderate intensity rainfall episodes, responsible for minor slope movements on the bank of rivers and shallow translational slides, particularly in artificial trenches; 2) high intensity rainfall episodes, originating flash floods and most landslides triggered by bank erosion; 3) long-lasting rainfall periods, responsible for the rise of the groundwater table and triggering of landslides with deeper slip surfaces.  相似文献   

10.
On October 23, 2004, a series of powerful earthquakes with a maximum M w = 6.6 located near the western coast of northern Honshu struck parts of northern Japan, particularly Niigata Prefecture; these earthquakes were known as the Chuetsu event. Thousands of landslides, as a secondary geotechnical hazard associated with these earthquakes, were triggered over a broad area; these landslides were of almost all types. The purpose of this study was to detect correlations between landslide occurrence with geologic and geomorphologic conditions, slope geometry, and earthquake parameters using two indexes based on Geographic Information Systems (GIS). In the study area, the landslide–area ratio (LAR), which is defined as the percentage of the area affected by landslides, was 2.9%, and the landslide concentration (LC), the number of landslides per square kilometer, was 4.4 landslides/km2, which is much more than other reported cases of seismic activity with the same magnitude. This was possibly due to heavy rainfall just before the Chuetsu earthquakes. Statistical analyses show that LAR has a positive correlation with slope steepness and distance from the epicenter, while LC is inversely correlated with distance from the epicenter. The Wanazu Formation had the most concentrated landslide activity, followed by the Kawaguchi, Ushigakubi, Shiroiwa and Oyama Formations, although the Wanazu Formation occupied only 4.5% of the total area of geological units. With 8.2% of the area affected by seismic landslides, the Kawaguchi Formation had the highest LAR. It was followed by the Shiroiwa, Ushigakubi and Wanazu Formations with LAR ranging from 4.6% to 6.0%. For lots of geological subunits, landslides are more frequent in a range of slope angles between 15° and 40°. The susceptibility to landsliding of each geologic unit was thus evaluated to correlate with slope steepness. It was also noted that the effects of the earthquakes were made far worse by antecedent rainfall conditions induced by a␣typhoon, and further research emphasizing the role of antecedent rainfall was discussed.  相似文献   

11.
溃屈型破坏是一种常见的顺层岩质边坡破坏模式,溃屈变形发展机制及失稳破坏的定量研究对滑坡工程勘查和防治指导十分重要。本文根据边坡的地质环境和力学作用机制,建立了三维受压板简化模型,其能够考虑岩层自身重力、地震力、静水压力的共同作用和岩体材料塑性变形的影响。基于弹塑性受压板稳定理论,利用能量法推导得到了边坡溃屈变形破坏的临界方程。对于溃屈型边坡的结构失稳和滑动失稳分别提出了相应的稳定性判定方法,并针对不同状态的边坡提出了相应的防治措施建议。以四川省甘孜藏族自治州巴塘县下归哇边坡为例,对所提判定方法的正确性进行了验证。计算结果表明,边坡的临界溃屈长度（a1）为483.8 m,说明下归哇边坡能够发生溃屈变形;现场勘查得知边坡实际溃屈长度（a′）为530.0 m,a′＞a1,可知边坡是稳定的。这与实际情况相吻合,由此证明本文所提出的判定方法可行。  相似文献   

12.
红层区边坡的变形破坏引发的地质灾害类型多、数量大,造成的人员伤亡和财产损失较大。以彝良县红层地区地质灾害为研究对象,结合实地调查,对彝良县红层边坡变形破坏所引发的49处不稳定斜坡、150处滑坡、53处崩塌进行了统计分析,总结了发育规律及特征。对不同斜坡结构下的红层边坡的成灾模式及破坏过程进行了分析,红层顺向边坡常见破坏模式为滑移-拉裂式;横向边坡常见破坏模式为崩解-冲刷式;反向坡、斜向坡的常见破坏模式为软岩崩解剥落-硬岩卸荷拉裂坠落式。研究可为彝良县等红层发育地区的地质灾害防治和管理提供一定的技术支持和参考。  相似文献   

13.
A Luoi is a Vietnamese–Laotian border district situated in the western part of Thua Thien Hue province, central Vietnam, where landslides occur frequently and seriously affect local living conditions. This study focuses on the spatial analysis of landslide susceptibility in this 263-km2 area. To analyze landslide manifestation in the study area, causative factor maps are derived of slope angle, weathering, land use, geomorphology, fault density, geology, drainage distance, elevation, and precipitation. The analytical hierarchical process approach is used to combine these maps for landslide susceptibility mapping. A landslide susceptibility zonation map with four landslide susceptibility classes, i.e. low, moderate, high, and very high susceptibility for landsliding, is derived based on the correspondence with an inventory of observed landslides. The final map indicates that about 37% of the area is very highly susceptible for landsliding and about 22% is highly susceptible, which means that more than half of the area should be considered prone to landsliding.  相似文献   

14.
On the basis of research and analysis of the landslide system of the Three Gorges Reservoir area, this paper systematically analyzes and studies the temporal–spatial distribution law of landslides of this reservoir area and their impacts on environment of this area. The paper puts forward that the temporal–spatial distribution of this area’s landslides is mainly controlled by lithologic characters of strata, geological structure, valley landscape, and types of bank slope structure; landslide deformation and failure have such characteristics as simultaneity, laggardness, cyclical instability, and stage. Besides, the paper systematically analyzes and studies the main impacts of landslide on environment and points out that landslides and collapses will bring about relatively serious impacts on relocation and layout of cities and towns along the banks. These impacts mainly include the increase of relocation investment, number of migrants, and compensation for losses. Much attention and evaluation should be paid to the impacts of Xintan Landslide and Lianziya Landslide—large landslides near the Dam—on the construction and safety of the Three Gorges Project. However, landslides have relatively small impacts on shipping and reservoir capacity. The above-mentioned research is of great guiding significance for the construction of the Three Georges Project, planning and construction of cities and towns along the banks, and protection of geological environment.  相似文献   

15.
On June 19, 1996, an extremely heavy rainstorm hit a restricted area in the Apuan Alps (northwestern Tuscany, Italy). Its max intensity concentrated over an area of about 150 km2 astride the Apuan chain, where 474 mm was recorded in about 12 h (21% of the mean annual precipitation, with an intensity up to 158 mm/h). The storm caused floods and hundreds of landslides and debris flows, which produced huge damage (hundreds of millions of Euros), partially destroyed villages and killed 14 people. This paper reports the results obtained from a detailed field survey and aerial view interpretation. In the most severely involved area, 647 main landslides were investigated, mapped and related to the geologic, geomorphic and vegetational factors of the source areas. This was in order to define the influence of these factors and contribute to an evaluation of the landslide hazard in the study area. An assessment was also made of the total area and volume of material mobilised by landsliding. The study area, about 46 km2 wide, includes three typically mountainous basins, characterised by narrow, deep cut valleys and steep slopes, where many rock types outcrop. Most of the landslides were shallow and linear, referable to complex, earth and debris translational slide, which quickly developed into flow (soil slip–debris flow). Usually, they involved colluvium and started in hollows underlain by metamorphic rock (metasandstone and phyllite), often dipping downslope. Therefore, bedrock lithology and impermeability appeared to be important factors in the localisation of the landslide phenomena. The investigation of the geomorphic and land use features in the source areas also frequently highlighted a rectilinear profile of the slope, a high slope gradient (31–45°) and dense chestnut wood cover. In the area, about 985,000 m2 (2.1% of 46 km2) was affected by landsliding and about 700,000 m2 of this area was covered by chestnut forest. The landslides removed about 7000 trees. The volume of mobilised material was about 1,360,000 m3; about 220,000 m3 remained on the slopes, while the rest poured into the streams. In addition, about 945,000 m3 was mobilised by the torrential erosion in the riverbeds.  相似文献   

16.
 An expert system is developed for evaluating failure potential of cut slopes and embankments. The fuzzy sets theory is used with the modified Monte Carlo simulation technique to obtain the Slope Failure Potential Index (SFPI) incorporating factors affecting slope stability, such as geology, topography, geomorphology, precipitation, vegetation and drainage conditions. The developed Cut Slopes and Embankments Expert System (CSEES) includes a classification system for evaluating failure potential of cut slopes and embankments, and a data bank on landslides in Jordan. The proposed classification system and slope failure-potential method proved to be successful for the areas that experienced landslides in the past. The expert system can be used directly for areas with the same geological formations as those areas in which landslides occurred in the past and can be used for areas with other geological formations by modifying the rock type or foundation-material type factor incorporated in the expert system. Received: 18 February 1998 · Accepted: 19 October 1998  相似文献   

17.
Rock slopes require geo-engineering evaluation to assess the instability of critical slopes leading to landslides particularly in Himalayan terrain where rocks are highly jointed, fractured and weathering prone. Interplay of discontinuities in the rocks coupled with other parameters is one of the prime causes of failure of slopes. Engineering rock mass classification, such as, rock mass rating (RMR) and slope mass rating (SMR) along with geological strength index (GSI) have widely been used for stability assessment of rock slopes above tunnel portals, and these classifications are employed here for assessment of stability of slopes of critical nature along Rampur-Powari highway in Himachal Pradesh. In the present study, out of 154 numbers of slopes, a total of 29 have been selected for assessment of their criticality by employing RMR, SMR and GSI.  相似文献   

18.
Yao  Jiaming  Lan  Hengxing  Li  Langping  Cao  Yiming  Wu  Yuming  Zhang  Yixing  Zhou  Chaodong 《Landslides》2022,19(3):703-718

The Sichuan-Tibet railway goes across the Upper Jinsha River, along which a large number of large historical landslides have occurred and dammed the river. Therefore, it is of great significance to investigate large potential landslides along the Jinsha River. In this paper, we inspect the deformation characteristics of a rapid landsliding area along the Jinsha River by using multi-temporal remote sensing, and analyzed its future development and risk to the Sichuan-Tibet railway. Surface deformations and damage features between January 2016 and October 2020 were obtained using multi-temporal InSAR and multi-temporal correlations of optical images, respectively. Deformation and failure signs obtained from the field investigation were highly consistent. Results showed that cumulative deformation of the landsliding area is more than 50 cm, and the landsliding area is undergoing an accelerated deformation stage. The external rainfall condition, water level, and water flow rate are important factors controlling the deformation. The increase of rainfall, the rise of water level, and faster flow rate will accelerate the deformation of slope. The geological conditions of the slope itself affect the deformation of landslide. Due to the enrichment of gently dipping gneiss and groundwater, the slope is more likely to slide along the slope. The Jinsha River continuously scours the concave bank of the slope, causing local collapses and forming local free surfaces. Numerical simulation results show that once the landsliding area fails, the landslide body may form a 4-km-long dammed lake, and the water level could rise about 200 m; the historic data shows that landslide dam may burst in 2–8 days after sliding. Therefore, strategies of landslide hazard mitigation in the study area should be particularly made for the coming rainy seasons to mitigate risks from the landsliding area.

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19.
The 2005 northern Pakistan earthquake (magnitude 7.6) of 8 October 2005 occurred in the northwestern part of the Himalayas. We interpreted landslides triggered by the earthquake using black-and-white 2.5-m-resolution System Pour l’Observation de la Terre 5 (SPOT 5) stereo images. As a result, the counts of 2,424 landslides were identified in the study area of 55 by 51 km. About 79% or 1,925 of the landslides were small (less than 0.5 ha in area), whereas 207 of the landslides (about 9%) were large (1 ha and more in area). Judging from our field survey, most of the small landslides are shallow rock falls and slides. However, the resolution and whitish image in the photos prevented interpreting the movement type and geomorphologic features of the landslide sites in detail. It is known that this earthquake took place along preexisting active reverse faults. The landslide distribution was mapped and superimposed on the crustal deformation detected by the environmental satellite/synthetic aperture radar (SAR) data, active faults map, geological map, and shuttle radar topography mission data. The landslide distribution showed the following characteristics: (1) Most of the landslides occurred on the hanging-wall side of the Balakot–Garhi fault; (2) greater than one third of the landslides occurred within 1 km from the active fault; (3) the greatest number of landslides (1,147 counts), landslide density (3.2 counts/km2), and landslide area ratio (2.3 ha/km2) was found within Miocene sandstone and siltstone, Precambrian schist and quartzite, and Eocene and Paleocene limestone and shale, respectively; (4) there was a slight trend that large landslides occurred on vertically convex slopes rather than on concave slopes; furthermore, large landslides occurred on steeper (30° and more) slopes than on gentler slopes; (5) many large landslides occurred on slopes facing S and SW directions, which is consistent with SAR-detected horizontal dominant direction of crustal deformation on the hanging wall.  相似文献   

20.
Characteristics of landslides in western Colorado,USA   总被引：1，自引：1，他引：0  
Mass movement can be activated by earthquakes, rapid snowmelt, or intense rainstorms in conjunction with gravity. Whereas mass movement plays a major role in the evolution of a hillslope by modifying slope morphology and transporting material from the slope to the valley, it is also a potential natural hazard. Determining the relationships of frequency and magnitude of landslides are fundamental to understanding the role of landslides in the study of landscape evolution, hazard assessment, and determination of the rate of hillslope denudation. We mapped 735 shallow and active landslides in the Paonia to McClure Pass area of western Colorado from aerial photographs and field surveys. The study area covers ～815 km2. The frequency–magnitude relationships of the landslides illustrate the flux of debris by mass movement in the area. The comparison of the probability density of the landslides with the double Pareto curve, defined by power scaling for negative slope (α), power scaling for positive slope (β), and location of rollover (t), shows that α?=?1.1, β?=?1.9, and t?=?1,600 m2 for areas of landslides and α?=?1.15, β?=?1.8, and t?=?1,900 m3 for volumes of landslides. The total area of landslides is 4.8?×?106 m2 and the total volume of the landslides is 1.4?×?107 m3. The areas (A) and the volumes (V) of landslides are related by V?=?0.0254?×?A 1.45. The frequency–magnitude analysis shows that landslides with areas ranging in size from 1,600 to 20,000 m2 are the most hazardous landslides in the study area. These landslides are the most frequent and also do a significant amount of geomorphic work. We also developed a conceptual model of hillslope development to upland plateau driven by river incision, shallow landsliding, and deep-seated large landsliding. The gentle slope to flat upland plateau that dominated the Quaternary landscape of the study area was modified to the present steep and rugged topography by the combined action of fluvial incision and glacial processes in response to rock uplift, very-frequent shallow landsliding, and less-frequent deep-seated landsliding.  相似文献   

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