Formation Mechanism Of Landslide Research Articles

Application of the electrical resistivity tomography in groundwater detection on loess plateau

Agricultural irrigation of the South Jingyang tableland in Shaanxi Province, China has led to a continuous rise of the groundwater level and has triggered a series of loess landslides, thereby seriously affecting the life and property safety of local residents. Research shows that the major cause of the landslide in the loess layer of the South Jingyang tableland is the rising groundwater level. Therefore, the research on the formation mechanism of landslide in this area should include the investigation of the stratigraphic structure and groundwater level distribution characteristics. On this basis, a series of approaches, such as electrical resistivity tomography (ERT), borehole, and laboratory tests, was carried out on the South Jingyang tableland, and the groundwater level distribution and stratigraphic structure in the study area were determined. The qualitative relationship between resistivity value and water content at different depths was detected using the inversion results of ERT and borehole data. Through laboratory tests, the quantitative relationship between resistivity values under different water contents was established. The precise depth of the groundwater level was inferred by connecting the qualitative relationship with the quantitative relationship, and then a detailed 3D geological model was established by linking the inversion results of ERT with the field borehole lithology data and geological survey data. The detection results show that when the qualitative and quantitative analyses of the ERT inversion results were combined, the distribution of the groundwater level was accurately judged. The ERT is effective in reflecting the stratigraphic structure and hydrological characteristics of the Loess Plateau, and its potential as a supplementary technology for detecting the groundwater level is reasonable. This study addresses the limitation and inaccuracy in determining the stratum structure and groundwater level by solely relying on borehole information or ERT. The established 3D geological model not only provides a basis for the study of groundwater table fluctuation, but also a technical guidance for the stability evaluation of loess slope, landslide prediction, and early warning in the study area.

The formation mechanism of landslides in typical fault zones and protective countermeasures: A case study of the Nanpeng River fault zone

Landslides are frequent in the Nanpeng River fault zone in southwest Yunnan. Based on a Zhen Qing Expressway survey, the geological conditions and characteristics of landslides in this area were studied. The conclusions are as follows: 1) the geological background was the internal cause of local highly steep slopes and broken rock masses. The main landslide types in study area are fault-type and accumulation landslides. 2) The formation of fault-type landslides is related to endogenous causes, such as tectonic movements, but they are less easily triggered than accumulation landslides. Accumulation landslides are related to broken rock masses and are sensitive to external factors such as rainfall and artificial unloading. 3) The coordinated control of permanent support engineering, local deformation control, and overall support reinforcement should be considered as preventive measures.

Failure Mechanism Analysis of Mining-Induced Landslide Based on Geophysical Investigation and Numerical Modelling Using Distinct Element Method

Underground mining activity in the karst mountain in southwestern China has induced several large-scale rocky landslides and has caused serious casualties. At present, there is a lack of systematic research on the formation mechanism of landslides in this area using multi-method fusion technology. First, the orthophoto images of the landslide area obtained by UAV photography were used to analyze the deformation characteristics of the landslide. Second, the failure characteristics of the strata overlying the goaf were analyzed by geophysical detection. Finally, the deformation response characteristics of the mountain under underground mining were analyzed by UDEC numerical simulation. The results revealed that during the underground mining, the failure process of the mountain occurred in four stages: fracture expansion, subsidence and collapse, shear sliding, and multi-level sliding. Gently dipping soft–hard alternant strata and a blocky rock mass structure formed the geological foundation of the landslides. Underground mining accelerated the fracturing of the overlying strata and the formation of a stepped penetrating sliding surface. Tensile movement of the structural planes of hard sandstone in the free face, and shear sliding of the weak mudstone layer, were the main causes of the landslides. The slope instability mode was tension-shear fracturing, shear sliding, back toppling, and compressive shear failure. In addition, the fracture propagation in the overlying strata and damaged geological structure revealed by the geophysical detection were consistent with the simulation results. This study provides ideas for the precise countermeasures of disaster prevention and mitigation for similar landslides in this area.

Pre-landslide topographic reconstruction in Baetis Chaos, mars using a CaSSIS Digital Elevation Model

Planview detailed morphological analysis of martian landslides is usually performed using orbital imagery such as from the ConTeXt camera (CTX) at 6 ​m/pix, the Colour and Stereo Surface Imaging System (CaSSIS) at 4.5 ​m/pix or the High-Resolution Imaging Science Experiment (HiRISE) at 0.25–0.5 ​m/pix. However, topographic information is key to fully understand a landslide's formation mechanism and its mobility, by estimating the material volumes mobilised and the spatial distribution of erosion and deposition. Digital Elevation Models (DEM) are required to carry out these analyses; nevertheless, there is currently a gap in landslide-volume studies between those using Mars Orbiter Laser Altimeter (MOLA) dataset at ∼450 ​m/pix or HRSC at 50–200 m/pix and those using HiRISE data at 1–2 m/pix, which is only partially filled by CTX elevation data at ∼20 ​m/pix. The CaSSIS camera on board the ESA/Trace Gas Obiter (TGO) can be used to produce DEMs, but so far, such data have not yet been used to conduct a landslide volume analysis. Here, we use three reconstruction methods (semi-automatic, morphology-based and tilted) on a CaSSIS DEM to estimate the initial topography and hence the volume and the distribution of erosion and deposition of a 6 ​km long landslide in Baetis Chaos. Despite the complex topography of the surrounding area due to the presence of an ejecta deposit beneath the landslide, we were able to estimate the landslide's volume and mass distribution. Using a tilted plane as part of estimating the initial topography produced the best results. We evaluated the success by considering the quantifiable balance between erosion and deposition (given the uncertainties) and more subjectively by considering whether the volume distribution matched with what was expected based on the morphology in images alone. Therefore, we recommend the use of this method for individual landslide studies in complex topography where detailed knowledge of the deposit-thickness distribution is required. The semi-automatic reconstruction method produces satisfactory volume estimates and would be better suited to studies where hundreds of landslides are present. We found that CaSSIS data can be used to successfully conduct such analyses, providing additional DEM coverage to study martian medium-scale landslides or other landforms of similar scale (5–15 ​km) with the notable benefit that it provides single-pass stereo image acquisition. • Digital Elevation Model are needed to estimates landslide's material volumes and distribution in order to fully understand their mobility. • CaSSIS (Colour and Stereo Surface Imaging System) DEM have not yet been used to conduct such landslide analysis. • Three reconstruction on a CaSSIS DEM have been used to estimate the volume and the material distribution of a landslide in Baetis Chaos on Mars. • CaSSIS data can be used to conduct analysis and provide additional coverage to study medium-scale landslides or other landforms (scale 5–15 km).

IDENTIFICATION OF WAVE DEFORMATION PROCESSES OF LANDSLIDES IN THE NORTHWESTERN BLACK SEA USING THE INSTRUMENTAL OBSERVATION DATA

Problem Statement and Purpose. At present, considering the conditions of slopes equilibrium, only the stresses caused by gravity, hydrodynamic and seismic effects are most often taken into account. As for tectonic stresses, their effect on landslide slopes has hardly been studied. At the same time, landslides and deformations ofslopes in a wide spatio-temporal range (with the frequency from several months to several dozens of years and the levels of massifs tectonic discreteness from first tensof meters to first kilometres) is also recorded in fact. Empirical data indicate that wave mechanism caused by rotational regime of the Earth can be one of the possible mechanisms explaining the high-frequency quasi-cyclic spatio-temporal variability of the rock mass stress-strain state. Purpose of the work has been to identify wave deformation processes in the Earth’s upper crust according to the data of instrumentalobservation of landslide slopes and relatively long line facilities deformation regime. In this work, we also intend to substantiate the thesis that wave exotectogenesis isone of the factors reducing the overall stability of landslide slopes. Data&Methods. The data of instrumental observations of structural components deformation in the underground drainage facilities of the landslide prevention works on Odesa coast that have accumulated during 50 years of operation, as well as the results of geodetic monitoring of landslide slope and the crest of plateau on the right bank of the Malyi Adzhalyk Liman within the territory of the Port Plant (ammonium plant) in 2000–2019 have been used to study the dynamics of deformation wave processes in the Earth’s upper crust. Statistical and cartographic analyses of the data sets mentioned above were carried out according to traditional methods using the Statistica, Matlab and Surfer software packages. Results. It has been found that modern dynamics of landslide slopes is significantly influenced by the periodic change of the stress-strainstate of rocks in space and time. The authors interpret the empirically revealed alternating in space zones of compression and extension, which cause the dynamics of vertical and horizontal reference benchmarks displacements in the inter-annual regime of marks displacement on the right bank of the Malyi Adzhalyk Liman and in the tunnels of Odesa coast as thereflection of wave geodynamics with periodic change of the stress-strainstate of rocks in space and time. Hierarchical layering of the tectonosphere in depth (the presence of layers with different elastic properties), tectonic discreteness and blockiness of rock massifs determine the spatial framework of the dynamically complex structure of the deformation field. Multiple cycles of compression-extensionof rocks lead to decrease in the rocks strength, accumulation of plastic deformations and activation of landslide displacements even on the coastal areas where anti-landslide measures have been implemented. To prepare design models correctly, it is important to take into account both the landslide formation mechanism and the factors that reduce the overall stability of the slope. The latter include the quasiperiodic variability of the rock mass stress-strain state controlled by rotational dynamics via wave mechanism.

Formation Mechanism and Stability Analysis of the Hejia Landslide

The existing research data show that, after reservoir impoundment, due to the repeated rise and fall of water level and water-rock interaction, the mechanical parameters of landslide are reduced, which will have an adverse effect on the stability of landslide. Therefore, sufficient attention must be paid to the stability of slope after reservoir impoundment. Hejia landslide is the largest landslide near the bank of Miaojiaba hydropower station, and its stability plays an important role in the normal operation of the hydropower station. Through field investigation and analysis of regional geological conditions, it is concluded that Hejia landslide is a large-scale landslide, through long-term sliding-bending deformation; it is generated from the external hard rock with thick layers and sliding zone for layered soft rock; the formation mechanism of landslide is as follows: (1) high-steep and hard-soft layered slope is the slope structure condition that caused the large landslide; (2) the existence of thick soft rock belt provides material conditions for the formation of slip surface; (3) certain air conditions provide displacement space for the separation and disintegration of the sliding body, and the landslide is stable at present. Numerical analysis results show that reservoir impoundment will adversely affect the stability of landslide. In order to ensure the normal operation of power station, certain engineering measures must be taken to treat Hejia landslide. After taking measures, years of monitoring data show that the deformation of Hejia landslide tends to be stable, and the current operation is normal, indicating that the engineering treatment measures are reasonable and feasible.

Acid rain: an unsuspected factor predisposing Panzhihua airport landslide, China.

Understanding the effect of acid rain to landslides is crucial for a better landslide risk assessment. This work aims to reveal the unsuspected but key role of acid rain in Panzhihua airport landslide, China. Firstly, we propose a hypothesis that acid rain may aggravate the slaking behavior of mudstone at weak interlayer and make it more fragmented, eventually further reducing its shear strength and predisposing the Panzhihua airport landslide. Subsequently, mudstone samples are subjected to slaking durability test, respectively, using water with a pH of 7 and two dilute hydrochloric acid solution with pH of 5 and 3. Slaking durability index (Idn) is adopted aiming to quantitatively evaluate the impact of acid rain on the slaking. Moreover, the mechanisms of acid rain affecting the slaking behavior of mudstone are revealed by (1) analyzing cation compositions changes in different pH slaking fluid and (2) observing micro-structure change of mudstone-chip before and after acid rain treatment. Finally, three works are conducted as evidences to prove that acid rain indeed plays a key role in the occurrence of Panzhihua airport landslide, including (1) analysis of the link between the slaking behavior of mudstone and its shear strength, (2) comparison of cations between spring water at the edge of the toe of landslide and acid rain, and (3) comparison of mineral contents of mudstone samples collected from different locations. These findings have implications for comprehensively analyzing the formation mechanism of landslide in acid rain area (such as Europe, North America, and China).

Effect of Soluble Salt Loss via Spring Water on Irrigation-Induced Landslide Deformation

Landslide exposes the previously blocked groundwater discharge. High concentrations of soluble salt form salt sinters that can be observed near discharge passages. Based on existing laboratory investigation results of soil leaching and shearing reported in the literature, the effect of the soluble salt loss via spring water on irrigation-induced landslide deformation was studied under large-scale conditions. During our field investigation of landslides in the Heitai terrace of the Yellow River’s upper reaches in Gansu Province, China, 35 spring outlets were found, and the Heitai terrace was divided into five subareas, based on the difference in spring flow. Deformation data for the terrace were obtained by small baseline subset technology (SBAS-InSAR). These data were analyzed in combination with the amount of soluble salt loss, to explore the correlation between the deformation of the landslide and the soluble salt loss in the loess irrigation area. The results showed that the cumulative deformation and the loss of soluble salt were increasing continuously in the terrace. Although the increasing intensity of each subarea was different, the changing intensity of the two during the corresponding monitoring period was highly consistent. The statistical analysis revealed a strong positive correlation between the accumulated loss of soluble salt via spring water and the accumulated displacement of the terrace edge (p < 0.01). After the slope k between the two was tested by the Grubbs test and t-test, the k was no abnormality (α = 0.05) and difference (Sig > 0.05), further providing the basis for confirming the existence of this positive correlation. When the loss of soluble salt in rock and soil increased gradually, the accumulated deformation of the terrace edge also increased continuously. The findings of this study are of great significance for understanding the formation mechanism of landslides and the identifying landslide revival in irrigation areas of the Loess Plateau.

A Multiple Method of Monitoring for Rainfall Induced Landslide

Landslide induced by rainfall is very common in the world, which seriously threatens the safety and construction. Taking the landslide on the right bank of the Xiajiang Water Control Project as an example, this paper carried out comprehensive monitoring of groundwater level, earth pressure, and surface deformation of the landslide analyzed the landslide formation mechanism and predicted the stability of the landslide. The results show that the rainfall infiltration caused fluctuations in the groundwater level of the slope, which caused the instability of liquefaction in the shallow surface layer, fluctuations in the reservoir reduced the stability of the slope. Groundwater activity between the bedrock and the soil-rock mixture controls the slope stability to a large extent. Based on the comprehensive impact analysis of these triggering events, it is considered that the slope is undergoing continuous deformation and needs to be landslide management.

Study on the formation mechanism of the landslide in the old cellar in Wanzhou

The natural geological conditions in the Three Gorges Reservoir Area are complex, which are the frequent and severe geological hazards in China. With the operation of reservoirs, the occurrence of geological hazards is aggravated. This not only causes great loss of life and property, but also destroys the geological environment and hinders the sustainable development of regional economy. Since the formation of Laojiaolin landslide in Wanzhou District, there have been many landslides and deformations, and the landslide body is densely populated and houses are dense. Deformation bodies often cause cracks and dislocations of main road facilities and residential buildings, triggered by extreme rainstorms, floods and other factors, which can cause sustained and rapid deformations, which will directly promote the inclination of residential buildings. The collapse has resulted in major disasters and accidents, which have posed a serious threat to the lives and property safety of the people in the region. It is of great practical significance to study the formation mechanism of landslides.

Process analysis of the Moxi earthquake-induced Lantianwan landslide in the Dadu River, China

Many large-scale landslides have occurred along the Dadu River, in particular in the middle section of the river, located on the eastern edge of the Qinghai–Tibet Plateau. The large-scale Lantianwan landslide was triggered by the 1786 Moxi earthquake (Ms = 7.75) at Luding, Sichuan province, China. Field investigations and 3D discrete element methods were used to examine the landslide formation mechanism and simulate landslide movement. The evolution of the landslide can be divided into four stages: initiation, high-speed motion, debris flow, and accumulation and river blocking. The results indicate that tension cracking and horizontal sliding were the geological origins of the Lantianwan landslide. The Moxi earthquake combined with the magnifying effect of the topography and the back slope formed deep-dip tensile structural planes in the Lantianwan slope, which triggered the landslide.

The formation mechanism of river erosion-induced loess landslide

The Jingyang South Plateau is located near the right bank of Jinghe river, belonging to Weibei Loess Plateau. Since the large-scale irrigation from 1976s, many river erosion-induced loess landslides have occurred in the Jingyang South Plateau. Landslide disasters has seriously affected local economic development and the safety of people’s live and property. To better understand the formation mechanism of landslides in this area, this paper uses field investigation, reduced triaxial compression shear test on saturated Q2 loess and numerical simulation to understand the formation mechanism of erosion-induced loess landslides. It is concluded that (1) Under the reduced confining pressure stress path, the yield strength of saturated Q2 loess is related to the initial confining pressure and shear rate. (2) The formation mechanism of river erosion-induced landslide of loess has been proposed: river erosion is the fundamental cause of river erosion-induced landslide of loess, and some blocks of soil laying at the foot of the slope plays a key character for the stability of the slope. This research could be helpful in preventing landslide disasters.

Response mechanism of post-earthquake slopes under heavy rainfall

This paper uses the catastrophic landslide that occurred in Zhongxing Town, Dujiangyan City, as an example to study the formation mechanism of landslides induced by heavy rainfall in the post-Wenchuan earthquake area. The deformation characteristics of a slope under seismic loading were investigated via a shaking table test. The results show that a large number of cracks formed in the slope due to the tensile and shear forces of the vibrations, and most of the cracks had angles of approximately 45° with respect to the horizontal. A series of flume tests were performed to show how the duration and intensity of rainfall influence the responses of the shaken and non-shaken slopes. Wetting fronts were recorded under different rainfall intensities, and the depth of rainfall infiltration was greater in the shaken slope than in the non-shaken slope because the former experienced a greater extreme rainfall intensity under the same early rainfall and rainfall duration conditions. At the beginning of the rainfall infiltration experiment, the pore water pressure in the slope was negative, and settling occurred at the top of the slope. With increasing rainfall, the pore water pressure changed from negative to positive, and cracks were observed on the back surface of the slope and the shear outlet of the landslide on the front of the slope. The shaken slope was more susceptible to crack formation than the non-shaken slope under the same rainfall conditions. A comparison of the responses of the shaken and non-shaken slopes under heavy rainfall revealed that cracks formed by earthquakes provided channels for infiltration. Soil particles in the cracks of slopes were washed away, and the pore water pressure increased rapidly, especially the transient pore water pressure in the slope caused by short-term concentrated rainfall which decreased rock strength and slope stability.

Variation of cavity gas pressure in slopes with weak intercalation under seismic load

This study discussed how cavity gas pressure affects the stability of rock mass with fractures under well controlled laboratory experiments. Suddenly-created void space created and the induced gas pressures have been the focus of active researches because they are associated with fast movement of large-scale landslides. A shaking table experiment was set up to mimic weak-intercalated rock slope under seismic loads. Excessive cavity gas pressure would be produced in weak spots upon a sudden vibration load. The drastically elevated gas pressure is believed to be responsible for the creation of cavities surrounding the tension fracture. With dissipation of the excessive cavity gas pressure, the fractures are in unbounded closed-state. This observation explains that the slope body would be split and loosened under several aftershocks, and with the expanding of the cracks, the slope failure eventually occurred. The research of the mechanism of cavity gas pressure could provide a novel insight into the formation mechanism of landslides under seismic load and has implications for the disaster prevention and control theory for the slope stability evaluation.

The Research on Loose Body Landslide Stability and Treatment

The formation of a loose engineering landslide is carried on, and the comprehensive analysis on the formation mechanism of landslide is studied. The stability checking is carried out. Accordingly, the treatments are put forward.

Landslide Formation Mechanism and its Control Measures in Dabaolang

Through analyzing Dabaoliang geological characteristics, this paper discussed the factors of the mechanism of landslide in Dabaoliang area and simulated its evolutionary process. The paper could get some conclusions, and the factors of landslide are as follow: the stability of the slope which mainly composed by clastic rock not only depended on the performance of the mudstone layer but also the skid resistance of the sliding surface and the shape of slope. Under the influence of regional structure, the joint fissures which developed along the boundary of the landslide will connect the crack and benefit the permeation of the surface water. The heavy rain is one of the main factors caused the slope unstable and sliding. Provide effective prevention and control for prevention and control of projects.

Stability Analysis and Treatment of a Landslide Engineering Along a Highway

This paper describes landslide rock-soil structure characteristics and physical-mechanical properties on the left side of a roadbed, and landslide formation mechanism and harm were analyzed in construction, with the transfer coefficient method and finite element method, the stability of the foundation and structures were evaluated, the stability coefficient and surplus sliding force of landslide were calculated, according to the calculation results, treatment measures are proposed, and the landslide stability were made comparative analysis before and after treatment, and that valuable experience and lesson were gained, which provide a strong basis for the landslide recognition and design, at the same time has a certain reference value for similar landslide governance.

Foreword: special issue on Wenchuan earthquake geohazards

A devastating earthquake of Ms 8.0 struck Wenchuan, Sichuan, on May 12, 2008. It lasted more than 80 s. The major faults extend 300 km from southwest to northeast. Thousands of aftershocks followed; 250 were Ms 4 or greater. Numerous surface fractures, landslides, avalanches, debris flows, and dammed lakes resulted. Landslides were the most widely distributed effect and have killed 20,000 people and destroyed traffic lines and property. Loose deposits from the landslides provide materials for debris flows. Debris flows have occurred in clusters in the quake area, resulting in 100 deaths. Historic reports from other earthquake areas indicate that such disastrous effects may continue for 10–20 years after the initial event. Scientists all over the world are researching the geohazards induced by Wenchuan earthquake. Many achievements have been made in better understanding formation mechanism, distribution, assessment and mitigation of geohazards induced by an earthquake. Some new research papers have been collected about the geohazards in the Wenchuan earthquake with the aim of promoting the development of formation mechanism, prevention methods and prediction theory of geohazards in an earthquake area. The goal of this special issue is to present lessons for those both planning for, and responding to the great earthquakes. Hopefully, these lessons can be used in the future to minimize human suffering and economic loss. This special issue contains 14 papers and this introduction on different aspects of the geohazards induced by Wenchuan earthquake. There are three papers that describe the geohazards triggered by Wenchuan earthquake: first, the study of the distribution characteristics and disaster chains initiated of geohazards after the Wenchuan earthquake; then, the analysis of the seismic damage of earth structures of road engineering according to the 41 roads that were investigated in the Wenchuan earthquake area. There are two papers on the study of the debris flow following the Wenchuan earthquake: one paper focuses on the enlargement of the debris flow volume and a new method conducted to predict the debris flow scales post-earthquake; the other is an analysis of the debris flow formation conditions which proposes the optimal characteristics of drainage canal to mitigation of the debris flow after the earthquake. There are six papers on the study of the landslide failure mechanism in the quake, activity characteristics, mitigation of technical and susceptibility and risk assessment of earthquake-induced landslides with the Subao River basin as an example. One paper uses the case of the Donghekou landslide to study the landslide formation mechanism. There are three papers on the analysis of the dammed lakes (quake lakes) induced by Wenchuan earthquake: one paper is on the study of the stability of the landslide dams which discusses the advantages and disadvantages of dammed lake development; two papers discuss the largest induced dammed lake as an example to simulate the dam breach development, risk assessment and discuss the flaws of the mitigation strategy in the disposal process and propose new methods to relieve the risk in an emergency. This special issue reflects formation, distribution, assessment and mitigation with the hopes of promoting the study of geohazards induced by an earthquake. The editors appreciate the generous response to the call for papers and also thank those who have served as technical and editorial reviewers with an aim of providing the best possible research.

Micromorphology of landslide soil

Landslide is one of natural catastrophes affecting national economy and people’s livelihood. There are many reports on the forming mechanism and control of landslide, but the studies on micromorphology of landslide soil are few. There are many potential landslides in the Three Gorges Region in China. In this paper, the micromorphologic features of the Jibazi landslide soil in Yunyang in the Three Gorges Region of the Yangtze River were studied using routine methods, that is, soil micromorphology, X-ray diffractometer and scanning electron microscope. The main conclusions are as follow: (1) The basic micromorphologic characteristics of the landslide soil are that the fine soil particles are commonly cohesive matrix, finer and lower content of skeleton grains, the microstructures are mainly types of phenocrystal gelatinization, densely chap and fissure structure. As a result, these micromorphologic features affect the discharging of soil water, favor the movement of landslide body and provide an internal basis of materials for the formation of landslide. (2) The concept on the forming material of landslide was proposed, and types of optical beamed clay aggregates, Fe-Mn isolates and glassy material were found in landslide-belt soil, which were remarkably different from the natural soil formation, and had some scientific significance in analyzing the forming mechanism of landslide and distinguishing the landslide-belt soil. (3) Some special micromorphologic and sub-micromorphologic characteristics, such as fingerprint microstructure, clay beamed bedding microstructure, oppressive microstructure, moulage microstructure and extending hole microstructure, could bring useful micromorphologic evidences for the observation and forecasting of landslide. The results mentioned above will bring helpful micromorphologic evidences for distinguishing slide soil, analyzing the formation mechanism of landslide, and monitoring and forecasting the occurrence of landslide.