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Background: On September 5, 2022, an Ms 6.8 earthquake occurred in Luding County, Ganzi Tibetan Autonomous Prefecture, Sichuan, China. The casualties and economic losses caused by the earthquake are huge. Most of the landslides triggered by this earthquake are small and medium-sized rock collapses and destructive debris flows, with a small number of large-scale landslides. Results: There are 5007 coseismic landslides in the Luding earthquake VII-degree area and above, with a total area of 17.36 km2. The landslides are generally distributed along the NW-SE direction. The highest landslide area density is 13.8%, and the highest point density of the landslide is 35.73 km2. High-density area is mainly concentrated in the IX-degree area and the northeast side of the seismogenic fault. Coseismic landslides are more likely to develop in the area with the slope more than 40°, the slope direction of 67.5-112.5 degree, and vegetation coverage of 40–50%. More landslides are developed in granite areas and forest areas. The closer distance to active faults, the more the coseismic landslides develop. The correlation between coseismic landslide development and the distance from the active faults is better than that between coseismic landslide development and the distance from the seismogenic faults. Conclusion: The landslide database used in this paper is the most perfect at present, and the research results have also been verified by fieldwork. This is also the first applied study of this landslide inventory, which indirectly confirmed the accuracy of the inventory. The results obtained in the manuscript will provide an important guideline for future disaster prevention and mitigation in southwest China. [ABSTRACT FROM AUTHOR]

The collection of relevant information about the vulnerability of infrastructure damaged by landslides is not an easy task due to the existence of several compounding factors and uncertainties. This makes it difficult to quantitatively estimate their vulnerability to slow-moving landslides. This paper presents a new vulnerability assessment model for masonry buildings on slow-moving landslides based on physical models and field observations. A masonry building model is made of brick and concrete at a scale of 1:10 to physically simulate the damage in structures caused by ground tension cracks commonly developed on slow-moving landslides. The tension crack opening process is simulated through a load-controlled table with an aperture on which the building model is constructed. The strain on the wall and its foundation were measured, and the damage of the model (crack formation and evolution for each loading step) was collected, described, and analyzed. These data were used to develop failure criteria for masonry buildings in rural areas in China in terms of a quantitative vulnerability curve. The quantitative model of vulnerability for masonry structures was established based on fuzzy mathematics and the Weibull function applied on the test data and observations. The vulnerability curve is verified with field cases of masonry buildings damaged by ground tension cracks associated with slow-moving landslides in the Three Gorges Reservoir area. The results support further testing and use of vulnerability curve proposed. [ABSTRACT FROM AUTHOR]

Based on an analysis of the formation mechanism, stability state and development trend, this paper focuses on monitoring key indicators, such as surface deformation and rainfall, to realize the early warning of landslides and provide some guidance for landslide disaster prevention and avoidance in the alpine mountainous area of Nangqian, Qinghai Province. The landslide of the Baima Elin Monastery has the topographic and geomorphological conditions of landslide formation and has the basic characteristics indicating that it can be influenced by rainfall and climate, so a landslide warning should be comprehensive. At the same time, the landslide is currently in an unstable state, and the seasonal freeze–thaw cycle will cause it to become more unstable. Based on macroscopic signs, it is predicted that the deformation of the Baima Elin Monastery landslide will continue to intensify without abatement, the stability will be further reduced after winter, developing in an unfavorable direction, and engineering measures should be taken as soon as possible to manage the landslide. [ABSTRACT FROM AUTHOR]

Rapid assessment of the distribution of earthquake-triggered landslides is an important component of effective disaster mitigation. The effort should be based on both seismic landslide susceptibility and the ground shaking intensity, which is usually measured by peak ground acceleration (PGA). In this paper, we address this issue by analyzing data from the Mw6.1 2014 Ludian, China earthquake. The Newmark method of rigid-block modeling was applied to calculate the critical acceleration of slopes in the study area, which serve as measurement of slope stability under seismic load. The assessment of earthquake-triggered landslide hazard was conducted by comparing these critical accelerations with the distribution of known PGA values. The study area was classified into zones of five levels of landslide hazard: high, moderate high, moderate, light, and very light. Comparison shows that the resulting landslide hazard zones agree with the actual distribution of earthquake-triggered landslides. Nearly 70% of landslides are located in areas of high and moderately high hazard, which occupy only 17% of the study region. This paper demonstrates that using PGA, combined with the analysis of seismic landslide susceptibility, allows a reliable assessment of earthquake-triggered landslides hazards. This easy-operation mapping method is expected to be helpful in emergency preparedness planning, as well as in seismic landslide hazard zoning. [ABSTRACT FROM AUTHOR]

Tunnel excavation in mountainous areas can sometimes reactivate or trigger landslides. The problem of tunneling-induced landslides may be influenced by not only the tunnel location and slope geological conditions but also construction deficiency without timely treatment. This paper presents a case study of Jimei landslide in Sichuan Province, China. This dormant landslide was largely induced by the excavation of a twin tunnel in the landslide body. Field investigation, slope movement monitoring, and numerical simulations show that the formation mechanism of the Jimei landslide triggered by tunneling can be summarized as follows: (1) The adverse geological conditions of stratified sliding mass consists of multilayer sliding surfaces and cracked sliding blocks. (2) The rock surrounding the tunnel underwent large and continuous deformation because of construction deficiency without timely treatment. (3) There was a reduction in the shear strength and increase in the bulk density of the sliding mass because of rainfall infiltration during the rainy season. [ABSTRACT FROM AUTHOR]

Landslides are common occurrences along Chinese rail routes. Accordingly, the accurate determination of sliding-surface locations and the underlying causes become critical from the landslide-disaster-management and loss-mitigation viewpoints. In this study, the landslide in the K66 section of the Jiheng Railway (installed in Jinggangshan City, Jiangxi, China) was investigated. The causative factors and characteristics of the landslide were analyzed using geophysical methods as well as drilling and monitoring techniques. The results reveal that a combination of the transient electromagnetic method and electrical resistivity tomography can be used to identify the location of water-rich landslide-prone regions. When combined with the drilling information, these results reveal the tendency of landslide occurrence in regions comprising strongly weathered carbonaceous shale. Moreover, an uneven slope deformation is observed along the railway line. The seepage of surface water into the slope is revealed as the primary cause of landslides. This is because the reduced strength of the strongly weathered carbonaceous shale facilitates the formation of sliding surfaces. This paper presents a comprehensive survey plan for landslides occurring along railway routes. Furthermore, an assessment of the risk of future landslide occurrences in the investigation area is presented, thereby providing an appropriate reference for landslide prevention and loss mitigation. [ABSTRACT FROM AUTHOR]

Landslide failure time prediction is considered a challenging issue in landslide research. A significant goal of landslide research is to provide scientific and accurate prediction methods. In this paper, the short-term forecasting of landslides (STFL) model is proposed by analyzing landslide deformation characteristics in a known evolution process. The landslides on the southern slope of the West open pit mine (SSWOPM) in Liaoning province, northeast China, and Huangci in Gansu province, northwest China, were selected as the study cases. After pre-processing, which include eliminating abnormal data (t test), adding missing data (cubic spline interpolation), and smoothing noisy data (Savitzky–Golay filters), the displacement data are assembled to serve as the model's input parameters. The parameters of STFL can be obtained through the Levenberg–Marquardt (LM) algorithm. Using the forecasting criterion, the time of failure of landslides can be predicted and determined. Forecasting results provide evidence that the STFL model can achieve an accurate prediction of landslide displacement (correlation coefficient R2 > 0.99). The forecasting results of the SSWOPM and Huangci landslides indicate that the forecasting failure time of the STFL model is March 10, 2014 and January 31, 1995, respectively, which are near the actual failure time compared with those obtained using the Verhulst model. This finding indicates that the new method has excellent reliability and accuracy in landslide prediction and a robust description of the landslide movement. [ABSTRACT FROM AUTHOR]

The Loess Plateau can be considered as a landslide-prone area in northwest China. The genera consensus about the interaction between landslide deposit and terrace sediments is not well studied; this paper summarised 40 loess landslides in the South Jingyang Platform, Shaanxi Province, China to help understand of this issue. Four of the loess landslides with high mobility have been analysed in detail. Three trenches T1, T2 and T3 dug after the loess landslides LD37, LD11 and LD38 highlighted the landslide-induced changes in geomorphology and internal geometry of geology, respectively. Furthermore, observation of upwards seepage flow on the profile of trench T3 is believed to be the trigger of the high speed, and long runout flowslides in the study area. A newly developed sandbox apparatus is used to reproduce the landslide kinematics due to a mass travelling over an inclined plane. The sandbox experiments show that the sediments are sheared and pushed upwards after the collision with the deposits. The deposits are then wrapped in a space between sediments, which tends to form the 'sandwich' structure. The distal sediments are thrust when the loess deposits' kinetic energy consistently dissipates, developing the accumulated folded strata. These results reveal the deposits' interactions with the sediments in the study area and provide key guideposts regarding prevention and mitigation of loess landslide hazards. [ABSTRACT FROM AUTHOR]

The 1718 great Tongwei earthquake in northwest China caused more than 300 large-scale landslides near the epicenter resulting in more than 70,000 deaths. Although previous studies agree that the earthquake-induced landslides in the area are loess-landslides, which slid along ancient terrain surfaces, there is a dearth of evidence to unravel the actual failure mechanisms of these widely-documented events. To clarify their characteristics and mechanisms, the landslides in Pan'an Town, located in Gansu Province, China were rigorously investigated. The field surveys revealed that the landslides occurred in an area comprising loess deposits of several tens of meters underlain by a basal mudstone layer. It was also revealed that instability in the area is strongly influenced by a river valley with large erosion bank slopes, as well as steep mudstone slopes, which are well developed. The majority of the landslides triggered by the Tongwei earthquake were loess-mudstone composite landslides, with the sliding surface in the deep mudstone. Three huge landslides on the northern mountain located at the river bend of Pan'an Town with a total volume of about 6.06 × 10 m are the main mass movements during the 1718 catastrophe. In addition, by taking the typical landslide named the Weijiawan landslide as a case study, the internal structure of the earthquake-triggered landslides and their stability were studied. The new findings not only aided the unraveling of the failure mechanisms but also provided insights and knowledge on early recognition of earthquake-triggered landslides in northwest China towns, especially in the surrounding valley, which shares similar geological conditions with landslides studied in this paper. [ABSTRACT FROM AUTHOR]

This paper describes a recent landslide event, which occurred at Liucheng village in Tianquan County, Sichuan Province, China, on July 15, 2018. The Laochang landslide described in this research is an outstanding and valuable reference for understanding the characteristics of such kind of landslides that are geologically similar to the landslide. The deformation characteristics of the landslide are investigated based on field investigations, drilled boreholes, and exploratory trenches. The 225 residents of 64 households living on the flat platform were threatened by the landslide. Therefore, to guarantee the safety of human life and property becomes the primary emergency task. The anti-sliding piles were taken to stabilize the landslide and mitigate impacts caused by the landslide. Based on the analysis of the monitoring data, the effectiveness of anti-sliding piles is evaluated. The results indicate that the anti-sliding piles are effective in increasing the stability of the landslide, and this work can provide a reference for similar slope engineering projects. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth analysis of the deformation characteristics and reactivation mechanisms of a giant ancient translational landslide in the Three Gorges Reservoir (TGR) based on more than 6 years of monitoring data with the assistance of in situ surveys. The Outang landslide, divided into three active parts, has a total volume of approximately 90 million m3 and slides along weak interlayers (WIs). Since the impoundment, the landslide has been experiencing persistent deformations with some distinct movement signs. The temporal displacements are marked by seasonal cycles of fast displacements in the summer followed by almost imperceptible movements for the remainder of each hydrologic year. The spatial displacement rates gradually increased with the increase in altitude. The primary triggering factors for slope movement could transition from the drawdown of the reservoir water to the periodic rainfall. The affected areas by the former and latter are mainly concentrated in the front part and the upper part of the slope, respectively. The landslide exhibited a composite push-retrogression-type failure evolution with the fluctuating reservoir levels destabilizing rock masses at the front part of the landslide and the precipitation mainly mobilizing materials in the upper part of the slope. Currently, the landslide is in a state of continuous movement. The toe area and upper part of the landslide should receive high priority for the development of preventative measures. [ABSTRACT FROM AUTHOR]

Most landslides induced by reservoir impoundment and rainfall in the Three Gorges Reservoir area of China are usually characterized by bedding-plane shear zones. This paper presents an experimental study of the interaction between water and shear-zone materials. A series of tests, including wetting-drying cycles and soaking tests, were carried out. The results show that the fluid-solid interaction not only reduces the shear strength of shear-zone soil but also accelerates the disintegration process of clastic rock from shear zone. After the fluid-solid interaction at different pH values, the clastic rock samples produce the most clay minerals in acidic solution. Similarly, the clay minerals of shear-zone soil samples increase dramatically after 45 days of soaking in acidic environment. According to the tests, it is found that the shear-zone soil in eluvium may originate from the weathered clastic rock near the shear zones under long-term fluid-solid interaction. [ABSTRACT FROM AUTHOR]

Double-row stabilizing piles are widely used to stabilize large-scale landslides. The construction process of double-row stabilizing piles is often accompanied by constructional time delay (CTD), which is defined as the time interval between the installation of front-row and rear-row stabilizing piles. The CTD is often selected based on the designer's experience and the construction arrangement due to the lack of design guidelines for double-row stabilizing piles. In this paper, the CTD is considered as a design parameter and optimized based on the robust design concept. The signal-to-noise ratio, which is a function of the mean and standard deviation of factors of safety (FOS) of the stabilizing piles, is used as a measure of the design robustness. The FOS of the double-row stabilizing piles are computed using an analytical model that considers the CTD. A framework based on the concept of robust design is proposed for determining the most preferred CTD considering multiple objectives, including safety, cost, and design robustness. This framework is illustrated with a case study, the Hongyan landslide project, Taizhou, Zhejiang, China. Based on the outcome of this study, the most preferred CTD is obtained. [ABSTRACT FROM AUTHOR]

Landslides are one of the most common geological hazards in many parts of the world, which have brought catastrophic consequences to mankind. Seismic shaking can be an important trigger factor generally resulting in large-scale landslides. For some paleolandslides triggered by earthquakes, despite the lack of historical records, certain paleoseismic parameters can be back-analyzed. In this paper, the discrete element method (DEM) was applied to back-analyze the peak ground acceleration (PGA) triggering the Tahman landslide, a paleolandslide located in eastern Pamir, northwest China. Firstly, detailed field geological and geomorphological investigation was conducted to reveal the natural and seismic characteristics of the landslide. Subsequently, discrete element modeling was carried out. Simulation results suggested that the Tahman rock slope was stable under natural conditions. Owing to arid climate and water shortage of the study area, the influence of water was ignored. Additionally, from the perspective of the occurrence time of the landslide and geomorphologic feature of the deposits, the landslide was not caused by glacier activity and freeze–thaw events, and thus, must have been triggered by an earthquake. A peak ground acceleration (PGA) of 0.55 g was found to be a critical value for triggering landslides, and a PGA of 0.76 g could best simulate the kinematic process of a landslide when the simulation results were calibrated against the current geomorphological features of the landslide deposits. It can be concluded from the present study that: (1) PGA amplification in the rock slope was related to the topography during earthquake excitation; (2) the effective duration of the seismic wave had a considerable impact on the back-analyzed PGA, which decreased with increasing effective duration; and (3) the long runout of the Tahman landslide was due to its large volume and the interaction of the slide mass with moraines. [ABSTRACT FROM AUTHOR]

Water impoundment of the Three Gorges Reservoir has induced more than 5,000 landslides or potential landslides. These are huge threats to the safety of the dam and the people living in the reservoir area. The deformation characteristics and failure mode of the landslides are important factors in landslide stability evaluation and reinforcement design. The work reported in this paper used the Zhujiadian landslide as an example to study the deformation characteristics and failure mode of the landslides in the Three Gorges Reservoir region. Field investigations were conducted to analyze the structure of the landslide. Then the deformations of the landslide were observed using an integrated monitoring system, including extensometer monitoring for crack development, GPS monitoring for surface displacement, and inclinometer monitoring for internal displacement. The results obtained suggest that the Zhujiadian landslide is a multi-rotational landslide containing three main rotational sub-landslides at present. The deformation and failure of this landslide have developed from front to back. The failure of the front part opens up space for the back part to slide forward into. The coupled actions of the reservoir water and rainfall have led to the failure of the Zhujiadian landslide. Finally, a risk evaluation of the water surge potentially generated by the landslide was conducted by calculating the maximum wave height at the opposite side of the river. The findings of this paper provide some useful information for the stability evaluation and reinforcement design of landslides in similar geological settings in the Three Gorges Reservoir area and in other parts of the world. [ABSTRACT FROM AUTHOR]

In this paper, an actual landslide process that occurred in Southern China is simulated by a continuum approach, the particle finite element method (PFEM). The PFEM attempts to solve the boundary-value problems in the framework of solid mechanics, satisfying the governing equations including momentum conservation, displacement-strain relation, constitutive relation as well as the frictional contact between the sliding mass and the slip surface. To warrant the convergence behaviour of solutions, the problem is formulated as a mathematical programming problem, while the particle finite element procedure is employed to tackle the issues of mesh distortion and free-surface evolution. The whole procedure of the landslide, from initiation, sliding to deposition, is successfully reproduced by the continuum approach. It is shown that the density of the mass has little influence on the sliding process in the current landslide, whereas both the geometry and the roughness of the slip surface play important roles. Comparative studies are also conducted where a satisfactory agreement is obtained. [ABSTRACT FROM AUTHOR]

The Jishishan Ms 6.2 earthquake occurred at 23:59 on December 18, 2023 in Gansu Province, China. We conducted a field survey to assess the hazards and damages caused by the earthquake and its associated geo-activities. Subsequently, we organized a seminar to discuss the possible causes of the destruction of a prehistoric site—Lajia Settlement—dated back to four thousand years B.P. and located only several kilometers away from the epicenter of the Jishishan earthquake. The Jishishan earthquake was unique for its hazard and disaster process, which featured ground shaking and a series of complex geological and geomorphological activities: sediment and soil spray piles, liquefaction, collapse, landslide, and mudflow along water channels. We define this phenomenon as the Jishishan earthquake ripple hazard (JERH). The most recent evidence from the JERH suggests that a prehistoric earthquake similar to the JERH, instead of riverine floods or earthquake-induced landslide dam outburst flood, as previously hypothesized, destroyed the Lajia Settlement. [ABSTRACT FROM AUTHOR]

There has been considerable research on the prolonged effects and evolution of post-earthquake landslides, as they are of significance for disaster relief and rebuilding plans in earthquake-impacted regions. There is a need to better quantify these prolonged effects and evolution based on the hydro-mechanical mechanisms of post-earthquake landslides. This study investigated the evolution of the hydro-mechanical behaviour and parameters of a single landslide by integrating experimental and theoretical analyses. Analyses were undertaken using a time series of in situ monitoring data over five hydrological years on a single landslide site in the Baisha River basin of Dujiangyan, in the Wenchuan earthquake region, China. Results indicated a linear increase in the angle of internal friction under prolonged effects, while soil cohesion decreased non-linearly, gradually approaching a lower limit. The saturated hydraulic conductivity ( K s ) increased, and the soil residual water content ( θ r ) evolution curve conformed to the Boltzmann function distribution model. The soil–water characteristic curve parameters gradually increased. Based on the hydro-mechanical parameter evolution, the spatiotemporal decay of the landslide over the next decade under extreme rainfall conditions was predicted using the rainfall slope stability models and TRIGRS. This paper proposed a mechanistic explanation for the prolonged effects of a post-earthquake landslide in response to rainfall. Furthermore, it provided a reliable theoretical basis for the early warning and prevention of such landslides. [ABSTRACT FROM AUTHOR]

Background: Landslides and landslide dams are a major natural hazard causing high socioeconomic risk in inhabited mountainous areas. This is also true for vast parts of south-western China, which are highly prone to slope failures due to several factors, such as a humid climate with high precipitation in the summer months, geological predisposing factors with highly weathered sedimentary rocks and a high seismicity. In order to assess possible run-out distances and the potential of landslides to block rivers, it is crucial to understand which factors influence landslide propagation and how they can be quantified. Since it is often difficult or impossible to measure related geotechnical parameters in the field, their back analysis with a numerical modelling approach can be useful. In this study a numerical modelling analysis was implemented for the case of a complex landslide in south-western China, which transformed into a debris flow and blocked the river and a major road after heavy rainfall. For this purpose a quasi-3D smoothed particle hydrodynamics (SPH) model that can account for geotechnical slope parameters, run-out distance, velocities, and deposition heights was used. Based on field observations regarding initial landslide volume and final deposition volume, height, and length, the mechanical properties of the landslide were estimated in a back-analysis. Results: Through stepwise parameter optimisation the best reconstruction of the observed deposition phenomena could be achieved considering an initial landslide volume of about 0.5 million cubic meters, a triggering height of 15 m, an height of the water table equal to half the soil thickness, initial pore water pressures of about 0.6 of the liquefaction value, and non-negligible bed entrainment, which resulted in a deposition with a volume of about one million cubic meters, a length of 615 m and a mean height of 11 m. Compared to models with other parameter combinations, here the total error was minimal, while the final deposition dimensions were only slightly overestimated with regard to the observations in the field. Conclusions: The paper outlines the potential for quantitatively interpreting the field evidence for the propagation of a complex flow-like landslide and related cascading processes, such as landslide damming. However, the analysis should take into account multiple features of the whole processes, such as the initial conditions at the landslide source area, the propagation pattern, the total volume mobilised, and the deposition characteristics. By doing so, the estimated model parameters can be implemented in future studies for the forward modelling of events at the same site, or other sites along this slope, in order to assess the potential of future river blockings through landslide deposits. [ABSTRACT FROM AUTHOR]

During rainfall infiltration and fluctuations in the water level, the seepage process of a landslide changes between a saturated and unsaturated state. The resulting landslide deformations do not occur immediately, but experience a time development with typical rheological properties. Slip-surface soil is a special kind of soil formed during the sliding process of a landslide, and its creep properties reflect the landslide dynamics process. The author conducted an unsaturated creep test on the slip-surface soil of a large landslide to study the unsaturated creep properties of slip-surface soil under different stress levels and matric suction conditions. The results showed that the unsaturated creep process of slip-surface soil includes an instantaneous deformation and attenuation deformation stage, which are mainly affected by the matric suction and net confining pressure. The extended Burgers creep equation (M-2 K) for the triaxial test of unsaturated soil was derived based on the test results, and the rationality of the model was verified by comparing its predicted values with experimental data. [ABSTRACT FROM AUTHOR]

Geological hazards, especially landslides and mudslides, are frequent in Caoke County, Sichuan Province, China. In September 2022, the mechanical parameters of the soil were obtained through a basic investigation of the landslide characteristics of Ni changgou. Upon that, the finite element-discrete element method was used to reconstruct the three-dimensional numerical model of the landslide on the right bank of Ni changgou, and the initiation mechanism of rainfall on landslide and the formation of debris flow impact dam process were simulated. Furthermore, the pore pressure, stability coefficient as well as displacement of the landslide body were analyzed. It turned out that with the increase of rainfall intensity, the pore water pressure value also increases, where pore water pressure rises rapidly. the slope is close to the unstable edge, Eventually, it tends to one under rainfall conditions, and due to gravity, the slide of the landslide is induced. The duration of landslide movement is about 200 s, the maximum average velocity of the landslide reaches 4.85 m/s, and the average movement distance is close to 500 m. In addition, this method is applied to the Chutougou debris flow, and the corresponding hazard analysis is added which could better show the treatment and application of debris flow in actual engineering. [ABSTRACT FROM AUTHOR]

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Abstract  The paper analyzes the characteristics and stability of the Jishixia landslide on the Yellow River in Qinghai Province, China, based on field investigations and various exploratory data. The current stability of the landslide was calculated and the future potential stability was assessed assuming a peak ground acceleration of 0.11g due to an earthquake, and the moisture created by flood discharge from the hydropower station. The results indicate that at present the overall landslide is stable, but further movement could be triggered by an earthquake event and/or significant wetting. [ABSTRACT FROM AUTHOR]

Slope stability models traditionally use simple indicators of root system structure and strength when vegetation is included as a factor. However, additional root system traits should be considered when managing vegetated slopes to avoid shallow substrate mass movement. Traits including root distribution, length, orientation and diameter are recognized as influencing soil fixation, but do not consider the spatial and temporal dimensions of roots within a system. Thick roots act like soil nails on slopes and the spatial position of these thick roots determines the arrangement of the associated thin roots. Thin roots act in tension during failure on slopes and if they traverse the potential shear zone, provide a major contribution in protecting against landslides. We discuss how root traits change depending on ontogeny and climate, how traits are affected by the local soil environment and the types of plastic responses expressed by the plant. How a landslide engineer can use this information when considering slope stability and management strategies is discussed, along with perspectives for future research. This review encompasses many ideas, data and concepts presented at the Second International Conference ‘Ground Bio- and Eco-engineering: The Use of Vegetation to Improve Slope Stability—ICGBE2’ held at Beijing, China, 14–18 July 2008. Several papers from this conference are published in this edition of Plant and Soil. [ABSTRACT FROM AUTHOR]

Take account of the characters of road geological hazard and its supervision, it is very important to develop the Road Landslides Information Management and Forecasting System based on Geographic Information System (GIS). The paper presents the system objective, function, component modules and key techniques in the procedure of system development. The system, based on the spatial information and attribute information of road geological hazard, was developed and applied in Guizhou, a province of China where there are numerous and typical landslides. The manager of communication, using the system, can visually inquire all road landslides information based on regional road network or on the monitoring network of individual landslide. Furthermore, the system, integrated with mathematical prediction models and the GIS’s strongpoint on spatial analyzing, can assess and predict landslide developing procedure according to the field monitoring data. Thus, it can efficiently assists the road construction or management units in making decision to control the landslides and to reduce human vulnerability. [ABSTRACT FROM AUTHOR]

Abstract  The paper discusses rainfall as a dynamic parameter in terms of the load–unload response theory, using the Xintan landslide in China as a case study. The computational results show that an abrupt jump occurs in the curve of the load–unload response ratio just before the landslide takes place. This indicates the potential of the dynamic parameter of rainfall for the prediction of colluvial landslides. [ABSTRACT FROM AUTHOR]

China's economic development is closely related to oil and gas resources, and the country is investing heavily in pipeline construction. Slope geological hazards seriously affect the long-term safe operation of buried pipelines, usually causing pipeline leakage, property and environmental losses, and adverse social impacts. To ensure the safety of pipelines and reduce the probability of pipeline disasters, it is necessary to predict and quantitatively evaluate slope hazards. While there has been much research focus in recent years on the evaluation of pipeline slope disasters and the stress calculation of pipelines under hazards, existing methods only provide information on the occurrence probability of slope events, not whether a slope disaster will lead to pipeline damage. Taking the 2015 Xinzhan landslide in Guizhou Province, China, as an example, this study used discrete elements to simulate landslide events and determine the risk level and scope for pipeline damage, and then established a pipe-soil coupling model to quantitatively evaluate the impact of landslide hazards for pipelines in medium- and high-risk areas. The results provide a reference for future pipeline disaster prevention and control. [ABSTRACT FROM AUTHOR]

Microstructural changes in the loess deposits due to the presence of joint planes is one of the primary causes of the geohazards (ground fissures, ground subsidence, landslides, collapses, and soil and water losses) that occur in the loess regions of western China. By means of uniaxial tensile tests and triaxial shear tests conducted under different confining pressures, we tested fractured loess Q samples with five fracture plane inclination angles (0°, 30°, 45°, 60°, and 90°) taken from Sanyuan County, Shaanxi Province in western China, where geohazards are prevalent. Analysis of the tensile stress-strain and shear stress-strain relationships of the fractured loess specimens revealed the characteristics of the fractures that induce instability in this area. These results provide important baseline data for future research on the mechanism of geohazards in the loess regions of western China. [ABSTRACT FROM AUTHOR]

The losses and damage caused by landslide are countless in the world every year. However, the existing approaches of landslide susceptibility mapping cannot fully meet the requirement of landslide prevention, and further excavation and innovation are also needed. Therefore, the main aim of this study is to develop a novel deep learning model namely landslide net (LSNet) to assess the landslide susceptibility in Hanyin County, China, meanwhile, support vector machine model (SVM) and kernel logistic regression model (KLR) were employed as reference model. The inventory map was generated based on 259 landslides, the training dataset and validation dataset were, respectively, prepared using 70% landslides and the remaining 30% landslides. The variance inflation factor (VIF) was applied to optimize each landslide predisposing factor. Three benchmark indices were used to evaluate the result of susceptibility mapping and area under receiver operating characteristics curve (AUROC) was used to compare the models. Result demonstrated that although the processing speed of LSNet model is the slowest, it still significantly outperformed its corresponding benchmark models with validation dataset, and has the highest accuracy (0.950), precision (0.951), F1 (0.951) and AUROC (0.941), which reflected excellent predictive ability in some degree. The achievements obtained in this study can improve the rapid response capability of landslide prevention for Hanyin County. [ABSTRACT FROM AUTHOR]

An empirical minimum intensity-duration ( I- D) condition of continuous rainfall for mudflows triggering is proposed for Yan'an, northern Shaanxi, China, where rainfall-induced mudflows occur frequently. Adopting the quantile-regression method, a program was built using R programming language and statistical computing environment, and 175 continuous rainfall records were analyzed objectively. The 35th percentile regression line was determined as the minimum I- D condition of continuous rainfall that can potentially trigger mudflows within the duration interval of 24-336 h, where I is measured in millimeters per hour and D in hours. Comparison of the minimum I- D condition of continuous rainfall determined by this study with those rainfall I- D thresholds developed for the world and other regions reveals that lower rainfall intensity has the potential to trigger mudflows in the Yan'an district, which proves the necessity of defining regional minimum rainfall I- D conditions and site-specific operational rainfall I- D thresholds for mudflows triggering in Yan'an. [ABSTRACT FROM AUTHOR]

The monitoring and prediction of the groundwater level (GWL) significantly influence the landslide kinematics. Based on the long-term fluctuation characteristics of the GWL and the time lag of triggering factors, a dynamic prediction model of the GWL based on the Maximum information coefficient (MIC) algorithm and the long-term short-term memory (LSTM) model was proposed. The Sifangbei landslide in the Three Gorges Reservoir area (TGRA) in China, wherein eight GWL monitoring sensors were installed in different locations, was taken as a case study. The monitoring data represented that the fluctuation of the GWL has a specific time lag concerning the accumulated rainfall (AR) and the reservoir water level (RWL). In addition, there were spatial differences in the fluctuation of the GWL, which was controlled by the elevation and the micro landform. From January 19, 2015, to March 6, 2017, the measured data were used to set up the predicted models. The MIC algorithm was adopted to calculate the lag time of the GWL, the RWL, and the AR. The LSTM model is a time series prediction algorithm that can transmit historical information. The Gray wolf optimization (GWO) algorithm was used to seek the most suitable hyperparameter of the LSTM model under the specific prediction conditions. The single-factor GWO-LSTM model without considering triggering factors and the support vector machine regression (SVR) model were considered to compare the prediction results. The results indicate that the MIC-GWO-LSTM model reached the highest accuracy and improved the prediction accuracy by considering the factor selection process with the learner training process. The proposed MIC-GWO-LSTM model combines the advantages of each algorithm and effectively constructs the response relationship between the GWL fluctuation and triggering factors; it also provides a new exploration for the GWL prediction, monitoring, and early warning system in the TGRA. [ABSTRACT FROM AUTHOR]

Dispersive clays are a type of clay in which clay particles are dispersed in low-salt water. Dispersive clays are widely distributed in Northeast China and have caused considerable engineering failures. In this study, we analyzed the engineering geological properties of dispersive clays, including grain size and mineral composition, physico-chemical indices, dispersibility, and physical and mechanical properties. We found that the dispersive clays contained the main minerals, including quartz, albite, potash feldspar, and clay minerals. High exchangeable sodium ion contents and high pH were the main controls on the dispersibility of the dispersive clays. Four types of dispersive clay failure were classified based on the studied characteristics, including erosion failure, piping failure, freeze–thaw cycle failure, and landslide failure. The erosion failure and piping failure influential factors of dispersive clays were determined by their engineering geological characteristics and external climate, including the dispersibility of clays, external water, and climate changes. The influential factors of freeze–thaw cycles failure were cold climate and water supply, and freeze–thaw and soaking were the main factors causing landslide failure. To control dispersive clay failures, we must prevent the frost heave failure and the soaking of dispersive clays with external water. Key methods to control include modification of the clays to improve their durability and isolating them from external water sources. [ABSTRACT FROM AUTHOR]

A novel machine learning ensemble model that is a hybridization of Bagging and random subspace–based naïve Bayes tree (RSNBtree), named as BRSNBtree, was used to prepare a landslide susceptibility map for Zigui County of the Three Gorges Reservoir Area, China. The proposed method is implemented by using the Bagging scheme to integrate the base-level RSNBtree model. To predict landslide susceptibility for the study area, a spatial database consisted of 807 landslides and 11 conditioning factors has been prepared. Evaluation of conditioning factors was conducted using the Pearson correlation coefficient and Relief-F method. The results indicate that all factors except the topographic wetness index can be accepted as modeling inputs. Particularly, the distance to rivers is the most important factor in landslide susceptibility prediction. The performance of landslide models was evaluated using statistical indices and areas under the receiver operatic characteristic curve (AUC). The support vector machines (SVM) and random forest (RF) were adopted for the comparison with our methods. Results show that the BRSNBtree (AUC = 0.968) achieves the highest prediction performance, which successfully refines the RSNBtree (AUC = 0.938) and outperforms the RF (AUC = 0.949) and SVM (AUC = 0.895). Therefore, the proposed BRSNBtree presents advantages in targeting landslide susceptible areas and provides a promising method for landslide susceptibility assessment. The developed susceptibility maps could facilitate effective landslide risk management for this landslide-prone area. [ABSTRACT FROM AUTHOR]

Strong earthquakes in mountainous regions can trigger massive landslides, and not just during the period of shaking. This study uses a time series of remote images to better understand the distribution of landslides near the epicenter of the 2008 Wenchuan Ms8.0 earthquake. We use multi-year high-resolution satellite images to interpret landslides and establish landslide inventories spanning from 2008 to 2019. Based on differencing pre-earthquake and post-earthquake digital elevation models (DEMs), we calculate the factor of safety (Fs, i.e., resisting forces versus driving forces) of slopes using a simplified Newmark model. Results show that landslide occurrence highly relies on slope stability, demonstrated by both co-seismic and post-seismic landslide mapping. According to the Fs analysis, which is closely related to the gradual slope change after the earthquake, most slopes within the study area stabilized after the 2008 Wenchuan earthquake, consistent with the decreasing trend of the landslide activity level. However, due to lithologic variation, the changes of post-earthquake slope stability may differ with landscape features in various regions and result in different geologic hazards. Thus, we highlight the necessity of continuous post-seismic monitoring and analysis of slope stability in different affected regions. The results of this work provide useful information for post-seismic infrastructure reconstruction and future earthquake disaster prevention in mountainous areas. [ABSTRACT FROM AUTHOR]

Sliding liquefaction is considered to be the cause of high-speed and long-distance sliding of some homogeneous loess landslides in western China. However, there is still a lack of necessary experimental research and analysis on the effects of sliding liquefaction on these landslides. In this work, the effects of sliding liquefaction on irrigation-induced, high-speed and long-distance loess landslides on the South Jingyang Tableland area in China are studied by performing large-scale ring shear tests and using the sled mode. The results are as follows. (1) There are two kinds of long-runout sliding modes of loess landslides on the South Jingyang Tableland: sliding along the terrace surface and sliding within the saturated terrace alluvium, which is associated with sliding liquefaction. Both sliding modes can lead to long-runout sliding. (2) There are some differences in the inclination of the sliding surface between the two sliding modes. Based on the inclination of the sliding surface, the corresponding sliding mode can be distinguished. (3) Under the two sliding modes, the large shear mechanical properties of the two-layer soil composed of loess and alluvial sandy silt show significant differences. The friction between the loess and dry terrace alluvium increases with increasing normal stress and shear rate, while the friction between the loess and saturated terrace alluvium presents the opposite trend. The results show that the sliding distances under different sliding modes present opposite trends with the change in sliding speed. (4) Based on the test results from the ring shear tests and the morphological characteristics of the sliding surface, the sliding mode and sliding distance of a loess landslide can be identified and predicted. [ABSTRACT FROM AUTHOR]

Seven landslides among the 110 landslides on the northeastern margin of the Tibetan Plateau in China were selected to analyze the structural development processes within the shear zones. In addition, the platy clay mineral content and mineralogical composition of the shear zone were also investigated. The samples obtained from the vertical profiles were quantitatively studied from top to bottom with respect to their material composition, pore structure, and water properties to understand the changes in the cementation and frictional properties of the shear zone. The results indicate that the structure is progressively modified by fractures, cleavage, and plasticization. Even though there is no sliding surface liquefaction, clayey particles are observed to exhibit slipping and rearrangement. The illite–montmorillonite mixed-mineral layer accumulates near sliding surface in the core zone, and the platy clay minerals are arranged along shearing direction for long shear displacement. [ABSTRACT FROM AUTHOR]

To clarify the sliding mechanism of a landslide, the shear behavior characteristics of slip zone soil are always vital. In the Northwest of China, thousands of landslides generally develop in three main types of slip zone soil, i.e., Quaternary loess, weathered Mesozoic-Cenozoic mudstone, and weathered Mesozoic-Paleozoic phyllite. In the present study, the shear behavior characteristics of these three kinds of slip zone soil were investigated through direct shear tests and their implications for the sliding mechanisms of landslide were also discussed. It was found that, in general, an abrupt failure of loess landslide could be related to the strong strain-softening behavior of loess in the direct shear test, while the ductile shear behavior of weathered mudstone and phyllite coincided with the creep deformation of the corresponding landslides. The residual friction angle of slip zone soil varied with the soil type and its mineral composition, and the lowest residual friction angle about 11.5° could be found in weathered phyllite (SET) with graphite. Compared with the previous research, it is interesting to find that the residual friction angles of mudstone and phyllite in the present study accorded reasonably with the empirical correlations proposed by Wen et al. (2007) for weak rocks in the Three Gorges area, China. [ABSTRACT FROM AUTHOR]

Simulation of the process of landslide occurrence, including deformation and failure, material movement and energy dissipation of slopes, can help in predicting the features, affected area and risk of potential landslides induced by earthquakes, thus providing support to decision-makers, which is of great practical significance in hazard prevention and mitigation. Taking the Chenjiaying potential landslide in Mian County, Shaanxi Province, China, as the scenario, this study used the discrete element method to develop a numerical simulation. The results showed that deformation of the slope started from the trailing edge, then gradually extended to the middle and leading edge until the failure occurred, via a progressive process. With the increase of the friction coefficient, the movement distance, velocity and failure time of the landslide were shortened, reduced and delayed, respectively, but the peak velocity remained at about 7.5 s after the seismic loading. The proportions of kinetic energy and collision energy in the total energy dissipation also decreased as the friction coefficient increased, but friction energy increased gradually, becoming dominant. The simulation also suggested that the landslide could not only bury houses to a depth of more than 3.8 m but also generate an impact of between 1.18 × 105 and 5.50 × 105 kN on the unit width of houses at the leading edge, which would pose a major threat to life and property safety for more than 50 households. These findings will aid in the assessment of landside risk caused by earthquakes. [ABSTRACT FROM AUTHOR]

Long-term agricultural irrigation on the top of the loess tableland will cause the toe of the slope to be eroded by seepage, which will induce repeated landslides. The coupled filter pipe and siphon drainage method (F&S method) is a new drainage method that combines existing methods and materials to focus on the mechanism by which seepage erosion occurs at the toe of the loess slope. The method was tested in the laboratory and the Heifangtai landslide group in Gansu Province, China. By testing the filtered water that was siphoned out during the tests and assessing the geomorphological changes after the field test, it was apparent that the F&S method effectively prevented the loess slope toe from being eroded and transported by the seeping groundwater. The drainage data and monitoring the groundwater level showed that the F&S method has a sensitive response capability and can automatically control the level of the groundwater. The results of the experiment with the physical model indicated the range of the influence of the F&S method on the loess, and this information, combined with the results of the field test, can be used to optimize the layout of F&S devices. The research showed that, compared with the methods that commonly are used to treat loess landslides, the F&S method has the advantages of strong pertinence, quick effect, simplicity, and low cost. This method is suitable for additional applications in loess areas. [ABSTRACT FROM AUTHOR]

There were many gently inclined shallow landslides along the soil-bedrock interface at a depth of 3–5 m in Nanjiang County, Sichuan Province, China. To explain why slope failure occurs at the soil-bedrock interface at a depth of 3–5 m, we conducted ring shear tests on samples of the slip zone soils, slip zone soil-to-the smooth bedrock, slip zone soil-to-the natural bedrock, and slip zone soil-to-the rough bedrock interfaces under various normal stresses. Twelve specimens of the slip zone soils and the slip zone soil-to-the bedrock of the gently inclined shallow landslides were tested by means of a ring shear apparatus. The results show that the peak shear strength and residual strength of the slip zone soils were larger than those of the slip zone soil-to-bedrock interface under a normal stress of 60–100 kPa. Thus, the slope slides along the slip zone soil-bedrock interface at a depth of 3–5 m. This can explain why the slope fails along the slip zone soil-bedrock interface at a depth of 3–5 m. The peak shear strength and residual strength of the slip zone soil-to-bedrock were larger than those of the slip zone soils under a normal stress of more than 100 kPa. Thus, the slope slides along the slip zone at a depth of more than 5 m. This can explain why the slope does not fail along the interface between the slip zone soils and the bedrock at a depth of more than 5 m. [ABSTRACT FROM AUTHOR]

The impoundment of the Three Gorges Reservoir in China inevitably caused the reservoir landslides to develop toward instability, which has attracted widespread attention. Taking the Huangtupo Riverside Slump 1# with the structural characteristics of double sliding zones as a case, this study focuses on the sliding zone soils in the hydro-fluctuation belt affected by the periodic fluctuations of reservoir water level. The wetting-drying cycles test is carried out to simulate the cyclic impact of the fluctuations on the sliding zone soils. Hence the weakening law of the strength parameters is illustrated and well characterized by an exponential function model. Considering the different number of wetting-drying cycles, the long-term reliability of the shallow and deep sliding surfaces is quantified via the imbalance thrust force method and reliability theory. The results indicate that the local failure probability of both sliding surfaces gradually rises as the number of wetting-drying cycles increases. In particular, the shallow sliding surface presents a greater local failure probability than that of the deep one since more slices are in the hydro-fluctuation belt. Besides, the sensitivity of the landslide response to the strength parameters is different, and the internal friction angle is much greater than the cohesion. The area of the hydro-fluctuation belt plays a significant role on the long-term reliability of the landslide, which should be closely monitored to guide the reservoir operation. [ABSTRACT FROM AUTHOR]

Loss Plateau of China is an area with long-term vegetation restoration while serious mass movements. Local vegetation does act as sediment reducing role while quantification of their effect on landslides is lacking. This work presents a first research work about the connection between landslides and vegetation by the example of July 25–26, 2013, extreme rainstorm. High-resolution sensing orthoimages, landside width, and simplified infinite slope theory were used to examine landslide distribution and the lateral apparent cohesion of roots. The results reveal that shallow landslides have a higher probability at the transitional slope area. The majority of them have a gradient of 20–25°, locate on south-facing slopes, and areas with sparse vegetation. Vegetation cover, represented by the Green-Red Vegetation Index (GRVI), is the controlling factor of landslide distribution and size. The estimated lateral apparent cohesion of plant roots is not positively related to GRVI, and increase when GRVI > 0.2. The relationship between landslide width and slope gradient indicates that strong root strength may result in larger landslide volume. This result of this work is a pioneering trial in correlating the lateral apparent cohesion from roots and forest crown, which is helpful for understanding the effect of vegetation on landslides. [ABSTRACT FROM AUTHOR]

Climate change has caused an increase in extreme rainfall and snowfall in many parts of the world. For example, in the Three Gorges Reservoir area, annual precipitation has gradually increased and the occurrence of heavy precipitation events has become more frequent. As the reservoir water level rises in October, the high water combined with heavy precipitation creates a "special hydrological environment," which recently caused the Yanguan landslide. The Yanguan landslide is a large-scale soil landslide that has undergone two slides, pushed the Yanguan Road Bridge into the reservoir, and caused serious damage to roads and buildings. In the present study, the combined effects of high water and heavy precipitation on landslide deformation characteristics (movement patterns and evolution processes) have been analyzed and a stability evaluation was conducted through a field investigation and numerical simulation. To comparatively analyze these combined effects of high water and heavy precipitation, a two-dimensional finite element model was created, and four cases of the hydrological environment were calculated with the model. Results show that the factor of safety was maintained in the range of 1.013 to 1.059 before the precipitation conditions changed. However, as heavy precipitation increased in October 2017 (reaching 356.4 mm in 1 month), this "special hydrological environment" potentially decreased the FoS to 0.948, which is 9.6% lower than that observed under normal conditions, and helped drive the Yanguan landslide activity. The analysis of these various combined effects can also indicate the impacts of climate change on landslides in other areas of the Three Gorges Reservoir. [ABSTRACT FROM AUTHOR]

The mapping unit is the smallest indivisible unit of landslide susceptibility mapping. The mapping unit considerably affects the effect of landslide susceptibility mapping. Among many mapping units, the slope unit is one of the most suitable units for landslide susceptibility mapping. The methods available for classifying slope unit are not uniform, and the dividing effects differ. In this study, the hydrological method and curvature watershed method were used to classify the slope units in the study area on the upper Jinsha River, south-western China. Lithology, slope angle, slope aspect, normalized difference vegetation index (NDVI), land cover, rainfall, curvature, distance-to-river, distance-to-fault, were selected as the landslide conditioning factors. Support vector machine were applied to the landslide susceptibility modeling. Statistical indexes, 5-flod cross validation, Kappa coefficient, and AUC values were introduced to validate the prediction accuracy of the landslide susceptibility model. By comparing the shape characteristics of slope units classified by the two methods, we found that the slope unit classified based on curvature watershed method has a uniform size, shape between circle and equilateral triangle, and small internal terrain variation. As for the mean prediction accuracy, Kappa coefficient and AUC values of landslide susceptibility model, in the training stage, were 81.62%, 63.23%, and 89.72%, respectively, for the hydrological method, while 84.26%, 68.51%, and 90.80%, respectively, for the curvature watershed method; in the testing stage, were 80.70%, 61.40%, and 88.08%, respectively, for the hydrological method, while 83.24%, 66.49%, and 88.96%, respectively, for the curvature watershed method, which means that the curvature watershed method is more effective to produce landslide susceptibility map of the study area. [ABSTRACT FROM AUTHOR]

A consequent slope, comprising weak planes in the same dip direction along the slope face, is the most dangerous type of rock slope. Herein, a consequent landslide that occurred on May 5, 2018, in Mabian County, Southwest China, was investigated. This landslide occurred in a region with a complex geological background and strong geological activity and is considered a typical consequent landslide. Field investigations and aerial photographic interpretations revealed that the rock mass slipped along the contact surface of the strongly and moderately weathered rock mass, triggered by continuous rainfall. A depth-integrated continuum method was used to study the dynamic process of the landslide. The applicability of the depth-integrated method was verified by comparing the moving boundary of the landslide extracted from a video with the simulation results. The results show that the velocity of the landslide first increased and then decreased from the top to the bottom of the landslide and reached a maximum of 21 m/s in the middle of the landslide. Based on this method, we predicted the potential danger zones and velocity distribution of unstable masses next to the Mabian landslide. On comparing the calculated results of a depth-integrated continuum method with the Scheidegger method, in the case of the Mabian landslide, a reduction factor λ was added to the Scheidegger formula to achieve a modified formula that determines the velocity of such consequent landslides relatively accurately. This work could provide reference for the study of landslide velocity and disaster prevention. [ABSTRACT FROM AUTHOR]

A mountain disaster chain always brings about potential danger to the safety of people and the environment based on its characteristics of long time-scale, great destructive power, and broad scope. Mechanisms responsible for this hazard are represented by studying a landslide-caused disaster chain that occurred in the bank of Jinshajiang River, China on 10 October 2018. The evolution process of this disaster chain is simulated and analyzed using a coupled model that consists of several depth-averaged equations, and the results agree well with the measured data. Furthermore, several factors, including frictional coefficient, inflow flux, and critical dam slope coefficient, are tested by applying different values. Results indicate that the evolution of a mountain disaster chain can change at each stage with different initial conditions. [ABSTRACT FROM AUTHOR]

In this study, the cluster analysis (CA), probabilistic methods, and artificial neural networks (ANNs) are used to predict landslide susceptibility. The Geographic Information System (GIS) is used as the basic tool for spatial data management. CA is applied to select non-landslide dataset for later analysis. A probabilistic method is suggested to calculate the rating of the relative importance of each class belonging to each conditional factor. ANN is applied to calculate the weight (i.e., relative importance) of each factor. Using the ratings and the weights, it is proposed to calculate the landslide susceptibility index (LSI) for each pixel in the study area. The obtained LSI values can then be used to construct the landslide susceptibility map. The aforementioned proposed method was applied to the Longfeng town, a landslide-prone area in Hubei province, China. The following eight conditional factors were selected: lithology, slope angle, distance to stream/reservoir, distance to road, stream power index (SPI), altitude, curvature, and slope aspect. To assess the conditional factor effects, the weights were calculated for four cases, using 8 factors, 6 factors, 5 factors, and 4 factors, respectively. Then, the results of the landslide susceptibility analysis for these four cases, with and without weighting, were obtained. To validate the process, the receiver operating characteristics (ROC) curve and the area under the curve (AUC) were applied. In addition, the results were compared with the existing landslide locations. The validation results showed good agreement between the existing landslides and the computed susceptibility maps. The results with weighting were found to be better than that without weighting. The best accuracy was obtained for the case with 5 conditional factors with weighting. [ABSTRACT FROM AUTHOR]

Understanding the hydrological mechanism of rainfall-induced shallow landslides is critical to make reliable predictive assessments and to reduce risks of economic loss and fatalities. An integrated approach was identified by combining the field-based monitored hydrological data with a hydro-mechanical analysis, which can be utilized to better understand seasonal hydrological features in shallow soils and the corresponding triggering mechanism of rainfall induced shallow landslides, with the aim of setting up an improved landslide early warning system. A hydrological monitoring system on a representative slope that was experiencing frequent local shallow failures in the Ren River catchment was constructed to provide available seasonal hydrological features with regard to time trends in volumetric water content and pore water pressure in shallow soils. A transition of vertical downward flow from unsaturated to near-saturated conditions has been fully detected since the significant saturation degree and associated pore pressure varies with vertical depths. Consequently, the triggering mechanism of shallow landslides should be associated with the combined effects of dissipation of matrix suction in the upper unsaturated zone and increased positive pore pressure due to the generation of a temporal perched water table in the deeper saturated zone. This process was confirmed through the field evidence and a back analysis on the long-term hydrological evolution of slope soil using a calibrated one-dimensional hydrological model. Antecedent hydrological conditions were also found to have an effect on rainfall intensity–duration thresholds in the landslide early warning system based on a hydro-mechanical analysis, with the aim of improving the accuracy of the model's predictive ability. The results indicated that this research promoted the effectiveness of a landslide early warning system through a hydro-mechanical analysis based on capturing the real hydrological features of a landslide. [ABSTRACT FROM AUTHOR]

The objective of this study was to produce a landslide susceptibility map along the rapidly uplifting section of the upper Jinsha River. Firstly, a total of 40 landslides were identified in the study area from the interpretation of remote sensing (RS) and field survey data. Following landslide identification, ten variables including slope angle, slope aspect, curvature, land use, normalised difference vegetation index (NDVI), rainfall, lithology, distance to river, distance to fault, and Strahler's integral value were selected as the influencing factors in landslide susceptibility mapping. All of the influencing factors were extracted by the slope unit. The Strahler's integral value was used to represent the relationship between the rate of uplift and rate of denudation in each slope unit. Furthermore, three methods, including logistic regression, a support vector machine, and an artificial neural network, were applied to landslide susceptibility modelling. Five-fold cross validation, a statistical analysis method, and the area under the receiver operating characteristic curve (AUC) were used to compare the evaluation results of the three models. Finally, the variance-based method was used to find the key factors associated with landslides in the study area. The results show that the mean prediction accuracies of the logistic regression model, artificial neural network model, and support vector machine model were 80.47%, 87.30%, and 83.94% in the training stage, respectively, and 81.08%, 82.16%, and 83.51% in the validating stage, respectively. The mean AUCs of the three models were 88.16%, 93.96%, and 89.68% in the training stage, respectively, and 87.68%, 92.60%, and 89.88% in the validating stage, respectively. These results show that the artificial neural network model is the best model for evaluating landslide susceptibility in this study. The landslide susceptibility map produced by the artificial neural network model was divided into five classes, including very low, low, moderate, high, and very high, and the percentages of the areas of the five susceptibility classes were 17.23%, 28.32%, 22.73%, 16.73%, and 15.00%, respectively. Furthermore, the distance to river, slope aspect, lithology, and distance to fault are the most important influencing factors for landslide susceptibility mapping in the study area. Consequently, this study will be a useful guide for landslide prevention, mitigation, and future land planning in the study area. [ABSTRACT FROM AUTHOR]

A catastrophic loess flow slide was triggered by the 2013 Minxian–Zhangxian earthquake in Yongguang village, Minxian County, Gansu Province, China. The landslide destroyed eight houses and killed 12 persons. The landslide involved the failure of 14.0 × 104 m3 of loess deposits from the source area. The displaced materials traveled 1000 m with an elevation descent of 180 m, covering an area of 4.2 × 104 m2. A numerical model (DAN3D) is used to simulate the post-failure behavior of the landslide based on a detailed field investigation. A combination of the frictional model and Voellmy model provides the best performance in simulating the landslide using trial and error. The simulation results indicate that the landslide lasted approximately 120 s and had an average velocity of 8.3 m/s. The final runout distance and deposit distribution are in a good agreement with the actual situation, indicating the accuracy of the simulated results. Therefore, it is expected that the models and parameters could improve the precision of hazard zonation for areas with geological, topographical, and climatic features similar to the Yongguang landslide area. [ABSTRACT FROM AUTHOR]