Landslide Development Research Articles

Historical reconstruction and evolution of the large landslide of Inza (Navarra, Spain)

In the winter of 1714–1715, a large rotational landslide originated on the northern slope of the Sierra de Aralar (Navarra, Spain), generating an earthflow that slowly descended through the valley for a kilometer and a half destroying the village of Inza. An interdisciplinary research recreated the historical process of the event and the geomorphological characterization of this large landslide. The geological analysis and hydrogeological characteristics of the site also identified the determining factors of this historical event. From the analysis that triggered the landslide and how the climate affected events can now be demonstrated from historical records of excess rainfall and the initial start of the process. From the recreated pre-failure topography, the stability of the original slope was studied using a 3D numerical model to identify the factors, causes and mechanism that controlled the development of the landslide.

New Insight into Post-seismic Landslide Evolution Processes in the Tropics

Earthquakes do not only trigger landslides in co-seismic phases but also elevate post-seismic landslide susceptibility either by causing a strength reduction in hillslope materials or by producing co-seismic landslide deposits, which are prone to further remobilization under the external forces generated by subsequent rainfall events. However, we still have limited observations regarding the post-seismic landslide processes. And, the examined cases are rarely representative of tropical conditions where the precipitation regime is strong and persistent. Therefore, in this study, we introduce three new sets of multi-temporal landslide inventories associated with subsets of the areas affected by 1) 2016 Reuleuet (Indonesia, Mw = 6.5), 2) 2018 Porgera (Papua New Guinea, Mw = 7.5) and 3) 2012 Sulawesi (Indonesia, Mw = 6.3), 2017 Kasiguncu (Indonesia, Mw = 6.6) and 2018 Palu (Indonesia, Mw = 7.5) earthquakes. Overall, our findings show that the landslide susceptibility level associated with the occurrences of new landslides return to pre-seismic conditions in less than a year in the study areas under consideration. We stress that these observations might not be representative of the entire area affected by these earthquakes but the areal boundaries of our study areas.

ГЕОДИНАМІКА

Purpose. The aim of the research presented in this article is to analyze the features of the reflection of the damage to the territory of the Transcarpathian region by landslide processes based on the anomalies in the magnetic and gravitational fields, taking into account tectonic zoning. The study is an important stage in predicting the landslide processes and it is aimed at reducing their negative effects on the environment. The relevance of the research is due to the growing intensification of landslides in the Carpathian region of Ukraine. Methodology. The development of landslides in each structural-tectonic zone is associated with its tectonic structure, and therefore these processes can have different intensity, dynamics, tendencies for further development and distribution area. Lithological-facies composition and bedding conditions of rocks form the physical and mechanical properties of rocks, determining the rate and mechanism of the development of landslides. The spatial confinedness of landslide processes in the fault zones is reflected in the gravitational and magnetic fields. Results. With the help of GIS MapInfo tools, a number of landslides in each tectonic zone, anomalies in the gravitational and magnetic fields, areas affected by landslides, the distance to the fault zones were calculated. The important result of the research is to prove a direct correlation between the spatial distribution of landslides and fault zones, tectonic structure, the lithological composition of rocks, which are reflected in gravimagnetic anomalies. Scientific novelty. The peculiarities of the reflection of the tectonic structure, zones of decompression, fragmentation of rocks and lithological composition in gravimagnetic fields on a regional scale are examined, and their association with landslide processes is evaluated for the first time. Practical significance. The theoretical substantiation of the peculiarities of the behaviour of gravimagnetic fields in the zones of distribution of landslide processes makes it possible to assess the natural conditions for the formation and development of landslides in a given region. The connection between the impact of the fault zones on landslide processes by their reflection in gravimagnetic fields is established, which can be used in the future for spatial forecasting of the development of landslides in territories with related structural-tectonic conditions.

RS AND GIS ANALYSIS ON RELATIONSHIP BETWEEN LANDSLIDE SUSCEPTIBILITY AND LAND USE CHANGE IN THREE GORGES RESERVOIR AREA

Since the construction of the Three Gorges Project,the land use types in the Reservoir Area have changed greatly. In order to get better coordination between landslide development and land use change since the impoundment of the Three Gorges Reservoir,this paper studies the land use change of the Yangtze River mainstream from Zigui to Badong,where is the head area of the Three Gorges Reservoir,based on image data in the year of 1987,2000,and 2010. The Landslide Area Modulus Ratio(Rsi) is used for analyzing and valuating the relationship between landslide development and land use change. The research result shows that:(1)From 1987 to 2010,the vegetation coverage rate in the study area decreased continuously,while the residential building area and cultivated land area increased continuously. (2)The Rsi value increases in vegetation area,cultivated land and residential building area in turn,increasing with the more intensive human activities,which indicates that landslide development is positively correlated with human activity intensity; (3)According to Rsi value,the study area is divided into three sub areas: high,medium and low area,and landslides are mainly distributed in high and medium areas,which is in good agreement with the actual situation. Therefore,it is necessary to consider the change of land use when carrying out landslide risk assessment in the reservoir area. This research is expected to provide theoretical support for land use planning,disaster prevention and mitigation in the Three Gorges Reservoir Area.

Depth-Integrated Two-Phase Modeling of Two Real Cases: A Comparison between r.avaflow and GeoFlow-SPH Codes

Due to the growing populations in areas at high risk of natural disasters, hazard and risk assessments of landslides have attracted significant attention from researchers worldwide. In order to assess potential risks and design possible countermeasures, it is necessary to have a better understanding of this phenomenon and its mechanism. As a result, the prediction of landslide evolution using continuum dynamic modeling implemented in advanced simulation tools is becoming more important. We analyzed a depth-integrated, two-phase model implemented in two different sets of code to stimulate rapid landslides, such as debris flows and rock avalanches. The first set of code, r.avaflow, represents a GIS-based computational framework and employs the NOC-TVD numerical scheme. The second set of code, GeoFlow-SPH, is based on the mesh-free numerical method of smoothed particle hydrodynamics (SPH) with the capability of describing pore pressure’s evolution along the vertical distribution of flowing mass. Two real cases of an Acheron rock avalanche and Sham Tseng San Tsuen debris flow were used with the best fit values of geotechnical parameters obtained in the prior modeling to investigate the capabilities of the sets of code. Comparison of the results evidenced that both sets of code were capable of properly reproducing the run-out distance, deposition thickness, and deposition shape in the benchmark exercises. However, the values of maximum propagation velocities and thickness were considerably different, suggesting that using more than one set of simulation code allows us to predict more accurately the possible scenarios and design more effective countermeasures.

Pre- and post-failure spatiotemporal evolution of loess landslides: a case study of the Jiangou landslide in Ledu, China

Pre- and post-failure spatiotemporal evolution of loess landslides: a case study of the Jiangou landslide in Ledu, China

Decadal Evolution of Landslides in the Siwalik Zone: a Case Study of Babai Watershed, Nepal

The Siwalik zone of the Nepal Himalaya is highly sensitive to landslides. The study of landslides in the catchment scale gives the basic concept of the overall landslides of the typical zone. In this study, the decadal evolution trend of the four largest landslides of the Babai River watershed was evaluated. The Landsat, Sentinel-2, and Google Earth imageries were used to obtain the physical data of the landslide from 2010 to 2019. The area, total length, and width of scar toe, and the body of landslides were obtained from the images. The rainfall data of two stations was used to evaluate the role of rainfall in the landslide development and evolution process. The trend of rainfall and area of landslides was not the same but the development process of all four landslides was more or less similar. The area of landslides fluctuated till 2014 but suddenly increased after 2015. The landslide area was highest in 2017 and moderately changed in 2018 and 2019. The landslides showed dynamic behavior in a decade with their typical expanding, widening, and reducing characters.

Automatic identification of continuous or non-continuous evolution of landslides and quantification of deformations

Automatic identification of continuous or non-continuous evolution of landslides and quantification of deformations

Depth integrated modelling of submarine landslide evolution

Submarine landslides are a major geohazard among worldwide continental slopes, posing significant threats to offshore infrastructure, marine animal habitats and coastal urban centres. This study establishes an original numerical package for time-efficient modelling of the entire submarine landslide evolution covering the pre-failure shear band propagation, slab failure and post-failure dynamics. The numerical scheme is based on the conservation of mass and the conservation of momentum and combines the shear band propagation theory and the depth-integrated method, with the consideration of the drag force from the ambient water. Shear band propagation in the weak layer and slab failure in the sliding layer are controlled by the strain softening and rate dependency of the corresponding undrained strength parameters. The post-failure behaviour in the sliding layer, such as retrogression upslope and frontally confined and frontally emergent mechanisms downslope, is also simulated. The numerical results from the proposed method are comparable to the analytical solutions and the large deformation finite element analysis. Application of this method to a back analysis of the St. Niklausen slide in Lake Lucerne reproduced the observed shape of the mass transport deposits, the position of the main scar and the travel distance. Because of its easy implementation and efficiency, the proposed numerical method for modelling of submarine landslides seems promising for practical applications.

Monitoring and Data Analysis in Small-Scale Landslide Physical Model

Physical modeling of landslides using scaled landslide models began in the 1970s in Japan at scaled natural slope physical models. Laboratory experiments of landslide behavior in scaled physical models (also known as flume or flume test) started in the 1980s and 1990s in Canada, Japan, and Australia under 1 g conditions. The main purpose of the landslide physical modeling in the last 25 years was research of initiation, motion, and accumulation of fast flow-like landslides caused by infiltration of water in a slope. In October 2018, at the Faculty of Civil Engineering University of Rijeka, started a four-year research project “Physical modeling of landslide remediation constructions’ behavior under static and seismic actions” funded by the Croatian Science Foundation. This paper presents an overview of the methods and monitoring equipment used in the physical models of a sandy slope exposed to artificial rainfall. Landslide development was monitored by observation of volumetric water content and acceleration as well as by observations of surface displacement by means of high-speed stereo cameras, terrestrial laser scanning, and structure-from-motion photogrammetry. Some of the preliminary results of the initial series of experiments are presented, and advantages and disadvantages of the used equipment are discussed.

Transient motion of the largest landslide on earth, modulated by hydrological forces

Sea-level rise of the Caspian Sea (CS) during the early Khvalynian (approximately 40–25 ka BP) generated hundreds of giant landslides along the sea’s ancient coastlines in western Kazakhstan, which extended hundreds of kilometers. Although similar landslides have been observed along the present-day coastlines of the CS in the area of a prominent high escarpment, it remains unclear whether some of these ancient landslides are still active and whether the movement is slow or catastrophic, as previously suggested. The present study is the first to show evidence proving that the geomorphic responses to sea-level changes of the CS that were triggered in the Pleistocene are currently active. Using interferometric synthetic aperture radar (InSAR) data, we show that one of these giant landslides occurring along the western shore of the Kara-Bogaz-Gol (KBG) lagoon of the CS presents active transient motion, which makes it the world’s largest active landslide reported thus far. Extending more than 25 km along the eastern coast of the inundated KBG depression in a N–S direction with maximum landward expansion of 5 km from the shoreline to the flat Ustyurt Plateau, this landslide conveys ~ 10 × 109 m3 rocks toward the lagoon at a rate of ~ 2.5 cm/year. This event releases a nearly episodic aseismic moment of 6.0 × 1010 Nm annually, which is equivalent to the response of an Mw 5.1 earthquake. We analyze the present-day evolution of this giant coastal landslide at high temporal and spatial resolutions using Sentinel-1 radar images acquired on descending and ascending modes every 12 days between 2014 and 2020. Modelling with elastic dislocations suggests that the KBG landslide was accommodated mostly by a shallow basal décollement with a nearly horizontal listric slip plane. Moreover, our analysis reveals week-long accelerating slip events at changing amplitudes that occur seasonally with slow, lateral spreading rather than sudden catastrophic motion. A strong correlation between the episodic slip events and seasonal water-level changes in the KBG lagoon suggests a causative mechanism for the transient accelerating slip events. Although water-level changes are widely acknowledged to trigger transient motion on a land mass, such movement, which is similar to a silent earthquake, has not been observed thus far at this mega scale; on an extremely low-angle detachment planes at < 5° with modulation by sea-level changes. This study suggests that present-day sea-level changes can reactivate giant landslides that originated 40–25 ka.

A data mining approach to the relationships between landslides and open-pit mining activity: a case study in Soacha (Cundinamarca)

Landslides caused by changes in land use, or by anthropic activities such as open-pit mining, constitute one of the most important socio-economic risk factors in countries with developing economies. This article presents an approach to the relationships between mining activity and the development of landslides in a pilot area located in Soacha, Cundinamarca. Through data mining analysis and the use of Geographic Information Systems (GIS), an evaluation of the possible relationships of these factors was carried out, including socioeconomic aspects. From an inventory of open-pit mining sites, the geomechanical characterization of soil and rock units, and the characterization of environmental and social variables, data were obtained to define variables whose relationships were determined by algorithms programmed in the GIS. The results show that there is an indirect relationship between open-pit mining activity and landslides development over the last four decades in the studied zone.

AI-Based Susceptibility Analysis of Shallow Landslides Induced by Heavy Rainfall in Tianshui, China

Groups of landslides induced by heavy rainfall are widely distributed on a global basis and they usually result in major losses of human life and economic damage. However, compared with landslides induced by earthquakes, inventories of landslides induced by heavy rainfall are much less common. In this study we used high-precision remote sensing images before and after continuous heavy rainfall in southern Tianshui, China, from 20 June to 25 July 2013, to produce an inventory of 14,397 shallow landslides. Based on the results of landslide inventory, we utilized machine learning and the geographic information system (GIS) to map landslide susceptibility in this area and evaluated the relative weight of various factors affecting landslide development. First, 18 variables related to geomorphic conditions, slope material, geological conditions, and human activities were selected through collinearity analysis; second, 21 selected machine learning models were trained and optimized in the Python environment to evaluate the susceptibility of landslides. The results showed that the ExtraTrees model was the most effective for landslide susceptibility assessment, with an accuracy of 0.91. This predictive ability means that our landslide susceptibility results can be used in the implementation of landslide prevention and mitigation measures in the region. Analysis of the importance of the factors showed that the contribution of slope aspect (SA) was significantly higher than that of the other factors, followed by planar curvature (PLC), distance to river (DR), distance to fault (DTF), normalized difference vehicle index (NDVI), distance to road (DTR), and other factors. We conclude that factors related to geomorphic conditions are principally responsible for controlling landslide susceptibility in the study area.

Long-term changes in the landslide sediment supply capacity for debris flow occurrence in Wenchuan County, China

After the Wenchuan earthquake, a large number of landslides in debris flow basins continued to provide loose debris for channels and further affected the occurrence of debris flows. Evaluating the landslide sediment supply capacity in debris flow basins requires understanding the landslide activity and the coupled relationship between the landslide and the channel. In this study, we proposed a model based on the landslide area density index (PAls) and the landslide connectivity (ICl) to evaluate the capacity of the landslide sediment supply for channels in 46 sub-catchments in the study area. The capacity of the landslide sediment supply for channels generally decreased from 2008 to 2018, but due to the influence of heavy rainfall, the actual capacity of the landslide sediment supply for channels in the study area may gradually diminish in an unstable way, and it may arrive at the pre-earthquake level by 2025 without the influence of extreme rainfall. However, higher debris flow activity may last longer than 2025 because sufficient gully materials are still accumulated in the channel. The sediment transport capacity of landslides was divided into five levels: extremely, high, moderate, slight and low. The capacity of the landslide sediment supply for channels changed from extreme levels and high levels to moderate levels and slight levels after the first 5 years of the Wenchuan earthquake and was then dominated by low levels. Simultaneously, the regions with higher landslide sediment supply capacities gradually changed from along the Minjiang River regions to the upper and middle reaches of the debris flow basin from 2008 to 2018. Hongchun gully, which is in the study area, was chosen as an example to compare the assessment results and field investigation. The long-term evolution of landslides is an important reason for the decrease in the sediment supply capacity of landslides.

Prediction interval estimation of landslide displacement using adaptive chicken swarm optimization-tuned support vector machines

Accurate and reliable displacement prediction is vital for developing landslide early warning system, since displacement variations directly reveal the evolution of landslide. The past decade has seen the rapid development of displacement prediction technology. Most of the existing studies are based on deterministic point prediction models, with the goal of obtaining high-precision predictions. However, these pointwise predictions do not give any indication of credibility, which makes it difficult to make accurate decisions for subsequent landslide treatment. To address this problem, a prediction interval estimation method, instead of point prediction, for landslide displacement is proposed. In the methodology, double exponential smoothing is employed to deal with the nonlinear cumulative displacement, while two support vector machines are proposed to directly generate the displacement lower boundary and upper boundary. To obtain optimal model parameters, the adaptive chicken swarm optimization using chaotic mapping and adaptive inertia weight strategies is proposed to minimize a modified prediction interval-based objective function. A real-world landslide displacement data set is used to demonstrate the proposed method. Experimental results show that it is a promising tool for the construction of high-quality prediction intervals, which can inform the landslide treatment-related decision-making.

Slope movement classification and new insights into failure prediction based on landslide deformation evolution

This study aims to investigate the features of landslide evolution from the perspectives of statistics and nonlinear systems. First, to understand the complex processes of landslide evolution intuitively, a new landslide classification based on deformation patterns is presented. Then, frequency-size statistics of velocity events are performed in five historical landslides, including four failure cases and one non-failure case. The results show that velocity events follow power-law distributions within a certain size range. The power-law behaviors are usually associated with a ubiquitous phenomenon of self-organized criticality (SOC). A statistical test indicates that some outliers with extreme sizes significantly exceed power-law extrapolation. One possible explanation is that they are “dragon-kings” (DKs), possessing different formation mechanisms from their peers in power laws. Herein, the role of SOC and DKs in landslide evolution is analyzed in detail. The two theories provide new ways to understand the underlying mechanisms of landslide evolution. Meanwhile, power-law distributions and DKs provide new insights to predict landslide deformation.

The dendrogeomorphic spatio-temporal reconstruction of flow-like landslides activity in one of the most susceptible region of Central Europe (the Vsetínské vrchy Mts.)

Flow-like landslides are a dangerous landslide type. They often express gradual movement or seeming dormancy, but occasional reactivation can, in extreme cases, result in catastrophic events. To predict their future behaviour, knowledge of past spatio-temporal development and relationships with hydrometeorological triggers is crucial. Moreover, regional data are more robust than case studies. Dendrogeomorphic (tree-ring-based) methods are a very precise approach for reconstructing past landslide behaviour. Nevertheless, regional reconstructions are very rare, which is probably due to their time-consuming procedures. This paper presents the results of a regional tree-ring-based reconstruction of the spatio-temporal development of flow-like landslides in a selected region in the Outer Western Carpathians. Six selected landslides were studied via analysis of 614 increment cores that came from 307 disturbed trees. The reconstruction provided data for approximately 70 individual landslide reactivation phases that were distributed in 44 event years. Events with regional extension (at least half of the studied landslides were active) were detected in six years (1940, 1941, 1953, 1961, 1985, and 1997). Periods of increased (1950s, 1990s) as well as decreased (1940s, 1970s, 2010s) landslide activity were reconstructed. The use of tree-ring data enabled the construction of landslide probability maps. Based on this analysis, all studied landslides exhibit extremely high probabilities of reactivation during a temporal horizon of 100 years, but even over shorter periods (5 and 20 years), their probability of reactivation is very high. Finally, analysis of meteorological triggers suggests the positive effect of precipitation in May (and possibly in September) to activate landslides with regional extent. Extreme short-duration (1-day) precipitation events probably do not play a role in landslide triggering. Moreover, gradual increases in precipitation totals during periods of at least one-half year preceding the event years were detected.

Activity evolution of landslides and debris flows after the Wenchuan earthquake in the Qipan catchment, Southwest China

The Wenchuan earthquake that occurred on 12 May 2008 induced numerous landslides. Loose landslide materials were deposited on hillslopes, and deep channels were easily remobilized and transformed into debris flows by extreme rainstorms. Twelve years after the Wenchuan earthquake, debris flows were still active in the Qipangou Ravine in the quake-hit area. In this paper, we continuously tracked the spatiotemporal evolution of the landslides and vegetation restoration and evaluated the evolution of debris flow activity in the Qipan catchment with the aid of a GIS platform and field investigations from 2008 to 2019. We observed that the area with active landslides increased sharply immediately following the earthquake, and then decreased with time; however, the total area of landslides continued to increase from 6.93 km2 in 2008 to 10.55 km2 in 2019. The active landslides shifted towards lower angles and higher elevations after 2013. Since 2009, the vegetation coverage has been gradually increasing and approaching the coverage present before the earthquake as of 2019. The landslide activity was high and the vegetation recovery rates were rapidly rising during the first five years after the earthquake; the recovery rates then slowed over time. Therefore, we divided the evolution that occurred during the post landslide period into an active period (2008–2013), a self-adjustment period (2013–2026) and a stable period (after 2026). We then proposed a quantitative model to determine the trends of landslide activity rates and NDVI values in the catchment, which indicated that the landslide activities and postseismic vegetation restoration rates in this catchment will return to preseismic levels within approximately two decades. We also analysed the runout volumes of the debris flows after the earthquakes (Diexi and Wenchuan) and the standard deviation of the vegetation coverage and predicted that the debris flow activities will last for an additional 50 years or more.

Changes in Floristic Composition of Meadow Phytocenoses on the Anthropogenically Eroded Slope

It is noted that the solution of geoecological problems largely depends on the availability of reliable and comprehensive information about the state of the geosystem and its development trends. The paper presents ecological-dynamic series reflecting changes in the floristic composition of meadow phytocenoses on the anthropogenically eroded slope under conditions of a developing landslide in 2000–2019. The data obtained make it possible to assess the degree of disturbance of the geosystem and can be used to plan economic and environmental protection measures. The article notes to reduce the anthropogenic load on such easily vulnerable biogeosystems as floodplain meadows located on a landslide slope near the built-up area, first of all it is necessary to identify the boundaries of the water protection zone and the coastal protective zone in the site of landslide process, to provide soil consolidation and to restore the vegetation cover, to organize groundwater discharge points on slope, to catch and to organize and surface runoff treatment. It is important to carry out engineering measures for monitoring the landslide development in order to prevent the adverse consequences.

Analysis of the failure modes and development of landslides using the material point method

Abstract Mass movements are frequent natural phenomena and especially dangerous due to increased population and irregular settlements in mountainous areas. Carrying out studies using methods that allow the numerical evaluation of their behavior is essential to mitigate and prevent these events' possible impacts. The traditional Limit Equilibrium and Finite Element methods fail to reproduce the problem from the beginning of the movement until the end of its development, so it is necessary to use new formulations. In this work the Material Point Method was selected to evaluate these movements in the stages of failure mode formation and development of landslide through an analysis of the soil shear strength and deformability parameters of a slope using the elastoplastic model with Mohr-Coulomb failure criterion. Maintaining a geometry and assuming soil mass behaves like a fluid, a single strength parameter and a single deformability parameter are analyzed to understand their influence before and after the failure.