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Perceptions of risk are a key issue when seeking to develop systems, practices and policies to protect local populations. This is particularly evident when risk mitigation strategies involve non-structural measures such as relocation and warning systems which presuppose the active involvement of the communities in question. This study adopts an interdisciplinary approach to studying the perceptions, knowledge and opinions on landslide risk amongst residents in Sarno, a small town in Southern Italy which was hit by disastrous landslides on 5-6 May 1998. The paper presents the results of a survey conducted in the months of March, April and May 2013 using a purpose-designed questionnaire. The survey was conducted using face-to-face interviews with 100 residents, 60 of whom live inside the so-called 'red zone', a territory declared at high residual risk soon after the events of 1998. The questionnaire included questions relating to perceived risk exposure, trust in institutions responsible for risk management, evaluations of risk mitigation measures and the early-warning strategy. The results of the study clearly emerges, amongst other issues, that the organisms which are responsible for risk management in Sarno need to develop more effective communication strategies in order to transmit knowledge about the actions implemented to reduce landslide risk in the area. [ABSTRACT FROM AUTHOR]

Eighteen (18) retrogressive thaw slumps (typical landslides in ice-rich permafrost) in northern Canada were monitored for 3 years to investigate the characteristics of their retrogressive behaviour. The head scarp retreat distances and scarp wall heights were measured annually. The first year monitoring results from 13 of the sites were released earlier, which demonstrated a correlation between thaw retrogression rate and scarp wall height. More data were obtained from a subsequent 2 years of monitoring and with five monitoring locations added. The additional data enhanced the initial findings that the retrogression rate increased with the increase of the scarp wall height. An updated correlation between the retrogression rate and scarp wall height is presented in this paper. The effect of slope orientation on thaw slump retrogression was also investigated. The data provided evidence that the occurrence of the retrogressive thaw slumps had no preference over slope orientation. The retrogression rates were also not affected by the slope facing direction. [ABSTRACT FROM AUTHOR]

This paper analyzes the effects of a historical rain series on pore water pressure distribution in the Costa della Gaveta landslide, in the Southern Apennine, Italy. The effects of pore water pressure variations on the safety factor and on the displacement rate of the landslide are also analysed. The aim of the investigation is to reach a deeper understanding of the influence of hydrological parameters on the mechanism of movements of the widespread type of active, very slow landslides in fine-grained soils. Pore water pressures were evaluated by means of the 3D finite difference code MODFLOW, applying as boundary condition the long historical rainfall series of the site. The transient analysis carried out with a daily resolution successfully reproduces the trend of piezometric data. The results show that because of the subsoil low permeability ( k = 10-10 m/s), pore water pressure variations caused by rain are significant only at depths lower than about 10 m. Furthermore, noticeable depth-depending time lag is evaluated between the external hydrological input and responses of internal pore water pressures. Pore water pressure variations on the shallowest areas of the slip surface have the greatest influence on the 3D limit equilibrium safety factor and thus on the landslide movements. As a matter of fact, the safety factor seems to be well correlated to the displacement rates evaluated by inclinometers at various depths, on the slip surface. The results of the 3D model provide pore water pressure distributions which are significantly different, both in value and in time trend, from those obtained by using 2D models. [ABSTRACT FROM AUTHOR]

On June 17 2017, the western coast of Greenland was the site of a tsunami which flooded several villages, killing 4 people and destroying 11 houses in the village of Nuugaatsiaq. This tsunami was triggered by a subaerial landslide which occurred in a fjord 32 km ENE of Nuugaatsiaq. This paper presents the numerical modeling of this landslide of ∼ 50 million m 3 and of the tsunami propagation from its source to Nuugaatsiaq. The landslide is considered as a granular flow under gravity forces and the water waves generated are related to the displacement of the sea bottom. The results obtained are similar in amplitude to our inferences from videos, i.e., three water waves between 1 and 1.5 m arriving at Nuugaatsiaq with a period of roughly 3 min, and are also in general agreement with the amplitude (1 m) resulting from deconvolution of oscillations recorded on a horizontal seismogram operating at Nuugaatsiaq (NUUG). According to the field survey performed by Fritz et al. (EGU General Assembly Conference Abstracts, Vol. 20 of EGU General Assembly Conference Abstracts, p 18345, 2018a) on July 2017, a second mass next to the landslide is threatening Karrat Fjord. A sensitivity study is realized on its volume, with 2, 7, 14 and 38 million m 3 reaching the sea. The shape of the water waves is found to be independent of volume, and linearity is observed between the volume and the water wave heights. Finally, the orientation of the slide does not seem to influence either the period or the shape of the generated water waves. [ABSTRACT FROM AUTHOR]

The focus of this paper is on two large sequential landslides which formed a dam and the resulting lake that occurred along the Jinsha River on October 11 and November 3, 2018. About 24 and 9 × 106 m3 of material failed and rushed into the river, respectively. Both landslides totally blocked the river and induced hazard chains. Four multi-temporal unmanned aerial vehicle (UAV)-based high-resolution images and digital elevation models (DEMs) before and after the landslides were obtained and merged. The initial deformation of the two landslides can be clearly captured by optical remote-sensing images and interferometric synthetic aperture radar (InSAR) analysis. The depth-integrated continuum method was adopted to analyze the dynamic process of both landslides, using the same basal friction angle and cohesion. The computational results matched well with field measurements and observations. It is shown that the evaluation of potentially landslide-prone areas by the depth-integrated continuum method is feasible and is able to provide significant information before a possible event. [ABSTRACT FROM AUTHOR]

It is a crucial issue to better understand the usability of Sentinel-1 satellites in geomorphologic applications, since Sentinel-1 and the Copernicus Program are considered to be the workhorse of Earth observation by the European Space Agency during the next decades. Yet, a very limited experience is available on the applicability of Sentinel-1 images in the detection and identification of surface deformations and especially landslide mapping and monitoring in densely vegetated (low-coherence) areas. Few Synthetic Aperture Radar images (not more than 20) are sufficient for a successful run of interferometric stacking algorithms. This number is really low compared to the tremendous data flow of Sentinel-1 images that are available for interferometric analysis nowadays. Despite the availability of acquisitions, only a few papers exist on the accuracy of Sentinel-1 data, signal-to-noise ratio and the value of the acquired imagery for geomorphologic interpretation. Two test sites and a control site—affected by active surface deformations—have been investigated using 40 Sentinel-1A images and conventional persistent scatterers (PSI) method. PSI results have been combined with the geomorphologic information of the studied sites. We verified that the given number of Sentinel-1A acquisitions provide a unique base for surface deformation recognition and mapping in low-coherence areas. We found that scatterers were corrupted by a strong noise if their line of sight (LOS) velocity was below ± 6–7 mm/year all over the three test sites, although noise can easily be reduced. Noise reduction was achieved by a significant increase of the length of time series, i.e., time range between the first and last image to reduce the effect of atmospheric phase screen (APS). [ABSTRACT FROM AUTHOR]

Landslides produce large quantities of sediment deposits and reduce reservoir life. This study investigated landslides at the Shihmen Reservoir basin in Taiwan that were induced by Typhoon Sinlaku and Typhoon Jangmi in 2008. We formulate scaling relationships between landslide erosion volume and area and conclude that sediment budget can be estimated based on the easier-todetermine landslide erosion area. The methodologies applied for the investigation were geomorphological analysis through 5 m × 5 m digital terrain models (DTMs) of the basin created before and after the landslide events and spatial analysis through a geographic information system. The erosion area and volume of landslides were measured through the subtraction of DTMs produced before and after the events. Statistical analysis revealed that the landslide erosion frequency-magnitude distribution exhibited power-law behaviors with a scaling exponent of 2.15 for the frequency-area distribution and 1.66 for the frequency-volume distribution. This paper proposes different scaling relationships for different moving depths, and landslide erosion volumes were estimated on the basis of depth; thus, landslides of different scales can be distinguished to avoid errors in volume estimation. Two different scaling exponents are proposed: 1.21 for landslide erosions with depths of less than 2 m and 1.01 for landslide erosions with depths of more than 2 m. The proposed scaling relationships are practical for landslide erosion volume estimation by different depths according to the landslide area, and they can provide preliminary results for sediment budget planning in a reservoir basin. [ABSTRACT FROM AUTHOR]

In this paper, we clustered and analyzed landslides and investigated their underlying driving forces at two levels, country and cluster, all over Iran. Considering 12 conditioning factors, the landslides were clustered into nine relatively homogeneous regions using the Contextual Neural Gas (CNG) algorithm. Next, their underlying driving forces were ranked using the Random Forest (RF) algorithm at country and cluster levels. Our results indicate that the mechanisms for landslide occurrence varied for each cluster and that driving forces of the landslides operated differently at a country level compared to the cluster level. Moreover, slope, altitude, average annual rainfall, and distance to the main roads were identified as the most important causes of landslides within all clusters. Thus, for effective management and modelling landslides on a large scale, the variation in the functionality of effective factors should be considered. [ABSTRACT FROM AUTHOR]

This paper presents the geometric and kinematic features of a landslide in Mabian, Sichuan, China, which occurred on 5 May 2018, derived from data of UAV photography. In combination with a field investigation, the UAV data permits to delineate the source area, overlap area, and accumulation area of this landslide. Coupled with DEM, its total source and accumulation volumes are estimated and the motion process is analyzed using the video record. The results show that Mabian landslide is a planar rocky downslope movement with a total horizontal projection area of 24,871 m2, source volume of 13,750 m3, accumulation volume of 213,200 m3, and the expansion rate of 55%. The sliding video demonstrates that the movement duration of the landsliding is about 16 s with a mean velocity 15.3 m/s, and the maximum velocity is 22.8 m/s. This study shows that the UAV-based aerial photography technology allow us to well characterize landslides rapidly in a quantitative manner. [ABSTRACT FROM AUTHOR]

Significant forces can be applied to embedded pipelines in sloping grounds due to soil instabilities, which potentially might lead to leakage of hazardous fluids into the environment. The soil-pipeline interaction in sandy slopes has been investigated experimentally using small-scale physical models tested in geotechnical centrifuge. A novel method is developed in this paper to estimate the ultimate external forces, induced by slope failures, acting on buried pipes at various locations inside the slope. Instabilities were triggered by surcharge loading on the slope crest in the centrifuge tests. Six dense coarse sandy slopes were tested with different pipe locations with respect to the slope crest. Moreover, two medium dense fine sand slopes were tested in the same manner to study the effect of the grain size distribution on the soil-pipe interaction. The external forces on the pipe induced by the surrounding soil movements were calculated based on the measurements of four strain gauges installed on the pipe. The shape of failure surface and pipe movements were monitored with the aid of advanced image analysis techniques. The results indicate that a buried pipeline has the potential to affect the slope failure mechanism. Normalised force-pipe displacement relationships were derived and compared to the estimation methods suggested in previous studies, which were mainly done on pipes installed in flat grounds. A new prediction method is introduced in this study, which considers the pipe burial distance to the slope crest. Moreover, the slope angle effect on the ultimate force applied to the pipe is also investigated, and a generalised formula is developed. Finally, two examples of the application of the new method are presented for pipelines installed at the toe of two large-scale subarial and submarine slopes. [ABSTRACT FROM AUTHOR]

This paper discusses the effect of the May 12, 2008 Wenchuan earthquake on a landslide where stabilization work had taken place and compares the results to sites without stabilization. Contours of shear strain increment and displacement values obtained using a FLAC3D simulation show that the Wangjiayan landslide, which had stabilization work, was stable before the Wenchuan earthquake. Simulations using input strong motion accelerations from the main shock recorded at Qingping station, within the main seismic fault zone, suggest a shear strain increment about 3,000 times more than it was before the main shock. Although the stability of the stabilized landslide decreased during the earthquake, the displacement values were very small. Modeled displacements suggest that the piles played a major role in keeping the slope from sliding. The anti-slide piles were subjected to high shaking acceleration. The strong ground motion records for a time range of 10 to 30 s show that the piles generally experienced accelerations in the range from 0.0 to 3.0 g, with a few spikes of about 5.0 g. Special observation stations were set up to monitor the slope motion at Qingchuan town, 150 km far from the Wangjiayan landslide, along the main central seismic fault zone, after the Wenchuan earthquake. The variation in acceleration with time and the FOS versus time of the Wangjiayan landslide were investigated using these acceleration records of the aftershocks as input data. The aftershock accelerations did not decrease the stability of the Wangjiayan landslide, but an amplification effect on the acceleration of the slope at different elevations was illustrated. [ABSTRACT FROM AUTHOR]

Landslides are one of the most destructive phenomena in nature and damage both property and lives every year. In this paper, a logistic regression model with datasets developed via a geographic information system and remotely sensed data was used to create a landslide spatial susceptibility map for the Three Gorges Project reservoir region on the Yangtze River in Zigui County. The five causative factors used in the logistic regression model were evaluated in different ways: topographic slope and topographic aspect were derived from a topographical map at 1:50,000 scale; bed rock-slope relationship and lithology were obtained from a geological map at 1:50,000 scale; and fractional vegetation cover (FVC), which represents the reduced frequency of landslides due to the vegetation canopy and ground cover and is also one of the most difficult parameters to estimate over broad geographic areas, was generated using a back propagation neural network (BPNN) method based on CBERS (China-Brazil Earth Resources Satellite) data, the results of which were compared with values measured in the field. The obtained Pearson correlation coefficient ( r) was 0.899. Then, the FVC factor and the other four factors were used as the input to a logistic regression model. By integrating the five factor maps in the geographical information system (GIS) via pixel-based computing, the landslide spatial susceptibility map was obtained. The study area was reclassified into four categories of landslide susceptibility: severe, moderate, low, and very low. Approximately 15.0 % of the study area was identified as severe susceptibility, and very low, low, and moderate susceptibility zones covered 21.8, 41.7, and 21.5 % of the area, respectively. These results have an accuracy of 78.90 %. Thus, by using a logistic regression model in a GIS environment, a spatial susceptibility map of landslides can be obtained, and the regions in Zigui County that are susceptible to landslides and need immediate protective and mitigation measures can be identified. [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]

Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied. Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism. Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample. [ABSTRACT FROM AUTHOR]

Landfills are the most popular means of disposing of construction solid waste owing to the low-cost, large treatment volume and strong adaptability. However, landfill collapses and landslides are common, posing a risk to lives and property. A catastrophic landslide, not triggered by heavy rainfall or earthquakes, occurred on December 20, 2015, at Hongao landfill in Guangming New district of Shenzhen, China. The collapsed waste soil flowed 1100 m down a slope with an elevation difference of 100 m. This catastrophic landslide is typical of long-runout disasters with high mobility, which result in great loss to life and property. In this paper, we focused on reproducing the flow processes and simulating the arriving area of the landslide at Hongao landfill using a full three-dimensional (3D) smoothed particle hydrodynamics (SPH) method. A series of undrained ring shear tests were conducted to determine the viscosity coefficient for the numerical simulation. The calculated geometry of the landslide using the full 3D SPH method agreed well with the field data. Hence, the combination of ring shear tests and SPH method can be widely used to predict the dynamic behavior of potential landslides in landfills, to reduce or prevent similar disasters. [ABSTRACT FROM AUTHOR]

On March 28, 2016, the toe zone of the apparently dormant Pergalla earthslide-earthflow (Northern Apennines, Italy) had a paroxysmal reactivation. In the course of 2 days, displacements up to almost 8 m severely damaged several houses and roads. At the bottom of the slope, the emersion of rotational sliding surfaces determined the uplift of almost 3 m of the Nure river streambed that was consequently partially dammed. The paper describes the landslide event on the basis of field surveys and analysis of post-event aerial photos, as well as data from geophysical surveys and pre- to post-failure displacement monitoring. It also discusses the possible concurrent causes of the event, including antecedent rainfall, the migration of active streambed channels of Nure river toward the landslide toe in the previous year, and the existence of long-term pre-failure slow movements. It is concluded that these factors, together with the presence of sliding surfaces extending beneath the valley floor, should be primarily considered if a preventive assessment of river damming potential due to streambed uplift should be made for other similar landslides in the Apennines. [ABSTRACT FROM AUTHOR]

The effect of variable rock mass properties on pile-rock interaction poses a great challenge to the design of stabilizing piles and numerical analysis of pile-rock interaction. The paper presents a novel method to estimate the properties of weathered bedrock, which can be applied to routine design of landslide-stabilizing piles for collivial landslides. The Ercengyan landslide located in the Three Gorges Reservoir, China, is the area of interest for this study. A geological investigation and triaxial tests were conducted to estimate the basic parameters, including Geological Strength Index (GSI), uniaxial compressive strength σci and Hoek-Brown constant mi of intact bedrock in the study area. Hoek-Brown criterion was used to estimate mechanical properties of the weathered rock, including elastic modulus Em, cohesion c, friction angle Φ, and normal ultimate lateral resistance pmax. A parametric study was performed to evaluate the effect of parameterizations of GSI, σci and mi on the bedrock properties and p-y curves. The estimated rock mass properties were used with PLAXIS 2D software to simulate pile-rock interaction. Effect of GSI on stress at the pile-rock interface and in the rock, pile bending moment, pile shear force, and p-y curve were analysed. [ABSTRACT FROM AUTHOR]

Consequence analysis is, together with hazard evaluation, one of the major steps of landslide risk assessment. However, a significant discrepancy exists between the number of published landslide hazard and landslide consequence studies. While various methodologies for regional-scale hazard assessment have been developed during the last decade, studies for estimating and visualising possible landslide consequences are still limited, and those existing are often difficult to apply in practice mainly because of the lack of data on the historical damage or on landslide damage functions. In this paper, an indicator-based GIS-aided methodology is proposed with an application to regional-scale consequence analysis. The index, called Potential Damage Index, allows describing, quantifying, valuing, totalizing and visualising different types of consequences. The method allows estimating the possible damage caused by landslides by combining weighted indicators reflecting the exposure of the elements at risk. Direct (physical injury, and structural and functional damage) and indirect (socio-economic impacts) consequences are individually analysed and subsequently combined to obtain a map of total consequences due to landsliding. Geographic visualisation of the index allows the delineation of the areas exposed to any type of possible impacts that could be combined with a corresponding map displaying landslide probability of occurrence. The method has been successfully applied to analyse the present consequences in the Barcelonnette Basin (South French Alps). These maps contribute to development of adequate land use and evacuation plans, and thus are important tools for local authorities and insurance companies. [ABSTRACT FROM AUTHOR]

Sassa and others in the Disaster Prevention Research Institute (DPRI), Kyoto University, developed a series of undrained ring-shear apparatus to physically simulate landslide initiation and motion, from DPRI-3 (Sassa ) to DPRI-7 (Sassa et al., Landslides 1(1):7-19, ). The maximum undrained capacities in the DPRI series ranged from 300 to 650 kPa. Sassa and others in the International Consortium on Landslides (ICL) have developed a new series of undrained ring-shear apparatus (ICL-1and ICL-2) for two projects of the International Programme on Landslides (IPL-161 and IPL-175). Both projects are supported by the Science and Technology Research Partnership for Sustainable Development Program (SATREPS) of Japan. ICL-1 was developed to create a compact and transportable apparatus for practical use in Croatia; one set was donated to Croatia in 2012. ICL-2 was developed in 2012-2013 to simulate the initiation and motion of megaslides of more than 100 m in thickness. The successful undrained capacity of ICL-2 is 3 MPa. This apparatus was applied to simulate possible conditions for the initiation and motion of the 1792 Unzen-Mayuyama megaslide (volume, 3.4 × 10 m; maximum depth, 400 m) triggered by an earthquake. The megaslide and resulting tsunami killed about 15,000 people. The Unzen Restoration Office of the Ministry of Land, Infrastructure and Transport (MLIT) of Japan systematically collected various papers and reports and published two summary leaflets: one in English in 2002 and an extended version in Japanese in 2003. Samples were taken from the source area (for initiation) and the moving area (for motion). The hazard area was estimated by the integrated landslide simulation model LS-RAPID, using parameters obtained with the ICL-2 undrained ring-shear apparatus. The estimated hazard area agrees reasonably with the landslide moving area reported in the Ministry leaflets. [ABSTRACT FROM AUTHOR]

This paper examines the public involvement processes contained within the Landslide Management Strategy for the District of North Vancouver in British Columbia, Canada. Following a fatal landslide in the Berkley neighborhood in 2005, the District of North Vancouver convened a community-based Natural Hazards task force to establish risk-tolerance criteria for natural hazards. This paper describes the community task force approach and evaluates it against four criteria for successful public involvement: representative participation; early involvement; information availability; and impact on policy. It is identified that the District could have incorporated a broader understanding of risk, allowing public perspectives to influence the initial framing of the risk issue before charging the Natural Hazards task force to arrive at quantitative risk-tolerance criteria. The District could also have sought to engage a somewhat more representative portion of the population to serve on the Natural Hazards task force, seeking to incorporate a broader set of public values and types of knowledge. Notwithstanding, the Natural Hazards task force successfully utilized social, legal, and scientific information for informed decision-making, and their recommended risk-tolerance criteria were enacted into policy by the District of North Vancouver as a result of the process. The paper also investigates the District's ongoing public involvement and education efforts with respect to landslide risks, considering information accessibility and its usefulness for increasing individual capacity and community resilience. Overall, the District's ongoing, dynamic approach to risk management promises to empower individuals and foster resilient communities in the aftermath of the tragic Berkley landslide. [ABSTRACT FROM AUTHOR]

Sliding mass of landslides highly endangered the area along travel path, especially landslides with long travel distance. It is necessary to develop an effective prediction model for preliminarily evaluating landslide travel distance so as to improve disaster prevention and relocation. This paper collected 54 landslides with 347-4,170 m travel distance triggered by the 2008 Wenchuan earthquake to discuss the effectiveness of various influential factors on landslide travel distance and obtained an empirical model for its prediction. The results revealed that rock type, sliding source volume, and slope transition angle were the predominant factors on landslide travel distance. The validity of proposed model was verified by the satisfactory agreement between observations and predictions. Therefore, this model might be practically applicable in Wenchuan earthquake area and other similar geomorphological and geological regions. [ABSTRACT FROM AUTHOR]

This paper illustrates the main characteristics of the newly developed landslide model r.massmov, which is based on the shallow water equations, and is capable of simulating the landslide propagation over complex topographies. The model is the result of the reimplementation of the MassMov2D into the free and open-source GRASS GIS with a series of enhancements aiming at allowing its possible integration into innovative early warning monitoring systems and specifically into Web processing services. These improvements, finalized at significantly reducing computational times, include the introduction of a new automatic stopping criterion, fluidization process algorithm, and the parallel computing. Moreover, the results of multi-spatial resolution analysis conducted on a real case study located in the southern Switzerland are presented. In particular, this analysis, composed by a sensitivity analysis and calibration process, allowed to evaluate the model capabilities in simulating the phenomenon at different input data resolution. The results illustrate that the introduced modifications lead to important reductions in the computational time (more than 90 % faster) and that, using the lower dataset resolution capable of guaranteeing reliable results, the model can be run in about 1 s instead of the 3.5 h required by previous model with not optimized dataset resolution. Aside, the results of the research are a series of new GRASS GIS modules for conducting sensitivity analysis and for calibration. The latter integrates the automated calibration program 'UCODE' with any GRASS raster module. Finally, the research workflow presented in this paper illustrates a best practice in applying r.massmov in real case applications. [ABSTRACT FROM AUTHOR]

Debris avalanches are complex phenomena due to the variety of mechanisms that control the failure stage and the avalanche formation. Regarding these issues, in the literature, either field evidence or qualitative interpretations can be found while few experimental laboratory tests and rare examples of geomechanical modelling are available for technical and/or scientific purposes. As a contribution to the topic, the paper firstly highlights as the problem can be analysed referring to a unique mathematical framework from which different modelling approaches can be derived based on limit equilibrium method (LEM), finite element method (FEM), or smooth particle hydrodynamics (SPH). Potentialities and limitations of these approaches are then tested for a large study area where huge debris avalanches affected shallow deposits of pyroclastic soils (Sarno-Quindici, Southern Italy). The numerical results show that LEM as well as uncoupled and coupled stress–strain FEM analyses are able to individuate the major triggering mechanisms. On the other hand, coupled SPH analyses outline the relevance of erosion phenomena, which can modify the kinematic features of debris avalanches in their source areas, i.e. velocity, propagation patterns and later spreading of the unstable mass. As a whole, the obtained results encourage the application of the introduced approaches to further analyse real cases in order to enhance the current capability to forecast the inception of these dangerous phenomena. [ABSTRACT FROM AUTHOR]

Seismotectonic activity and slope instability are a permanent threat in the archaeological site of Abakainon and in the nearby village of Tripi in NE Sicily. In recent times, signs of an ancient earthquake have been identified in the necropolis of Abakainon which dating was ascertained to the first century AD earthquake. The site is located on a slope of Peloritani Mts. along the Tindari Fault Line and contains evidence for earthquake-induced landslide, including fallen columns and blocks, horizontal shift and counter slope tilting of the tomb basements. In this paper, we used an integrated geomorphological and geophysical analysis to constrain the landslide. The research was directed to the acquisition of deep geological data for the reconstruction of slope process and the thickness of mobilized materials. The applied geophysical techniques included seismic refraction tomography and electrical resistivity tomography. The surveys were performed to delineate the sliding surface and to assess approximately the thickness of mobilized materials. The geophysical and geomorphologic data confirmed the presence of different overlapped landslides in the studied area. Moreover, a numerical simulation of the slope under seismic loads supports the hypothesis of a mobilization of the landslide mass in case of strong earthquakes (PGA > 0.3 g). However, numerical results highlight that the main cause of destruction for the Abakainon necropolis is the amplification of the seismic waves, occasionally accompanied by surficial sliding. [ABSTRACT FROM AUTHOR]

In this paper, the updating of the landslide inventory of Tuscany region is presented. To achieve this goal, satellite SAR data processed with persistent scatter interferometry (PSI) technique have been used. The updating leads to a consistent reduction of unclassified landslides and to an increasing of active landslides. After the updating, we explored the characteristics of the new inventory, analysing landslide distribution and geomorphological features. Several maps have been elaborated, as sliding index or landslide density map; we also propose a density-area map to highlight areas with different landslide densities and sizes. A frequency-area analysis has been performed, highlighting a classical negative power-law distribution. We also explored landslide frequency for lithology, soil use and several morphological attributes (elevation, slope gradient, slope curvature), considering both all landslides and classified landslide types (flows, falls and slides). [ABSTRACT FROM AUTHOR]

Considering the potential use of cementstabilized loess ( CSL) as a construction material for structures that are subjected to frequent loess landslides, this paper explores the stabilization and improvement of geotechnical characteristics of loess achieved by the addition of 0%-9% cement by dry weight. Laboratory evaluations investigated the consistency limits, compaction, compressibility, California bearing ratio ( CBR), direct shear strength, and unconfined compression strength ( UCS) of CSL for different curing stages. A durability index was quantified to estimate the influence of wetting-drying ( w-d) cycles on CSL strength, and an optimum cement dosage was also identified. The results reveal that the cohesion of CSL is substantially more sensitive to structure than its friction angle and that cohesion is responsible for shear strength increase after remoulding. The cement proportions have an effective role in the enhancement of compressibility. The development of UCS can be categorized into the early stage (<14 days) and the later stage (>14 days). The increase in strength primarily occurred in the first 14 days. The w-d cycles have a significant influence on the decrease in compression strength. The CBR value increases with increments of additional proportions and compaction times. The relationships of UCS versus the compressibility modulus and UCS versus CBR are established to facilitate the mix design for strength. A rational predictive exponential equation is proposed to predict the durability index for different w-d cycles. [ABSTRACT FROM AUTHOR]

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Seismic surges and landslides are both major secondary mountain hazards during an earthquake. This paper investigates earthquake- and landslide-induced composite surges through large-scale shaking table water tank model experiments. A series of tests were conducted for various initial water depths, peak ground accelerations, slide impact velocities, and slide volumes. Based on the results of the tests, the effects of these parameters on the maximum wave heights of the earthquake- and landslide-induced composite surges were analyzed. An amplification coefficient of seismic surges was defined, and the prediction equation for the amplification coefficient was developed through non-dimensional multiple linear regression analysis. Then, an empirical equation for the maximum wave heights of the composite surges was developed based on the amplification coefficient and Demirel's method. This equation provides a calculation method for earthquake- and landslide-induced composite surge waves. [ABSTRACT FROM AUTHOR]

On June 24, 2017, a catastrophic landslide destroyed the village of Xinmo (Maoxian County, Sichuan, China). A 2.87 × 106 m3 rock mass in source area collapsed and entrained the surface soil layer along the run-out path. This disaster took eighty-three people's lives and destroyed more than 103 houses. It is worth noting that rock fragmentation and grinding could expand the spreading area of danger zone in a landslide event. The Xinmo landslide provided a rare opportunity to infer the dynamic fragmentation and grinding of rock masses from the particle size and shape distribution in the entrainment and deposition area. A field investigation combined with an automatic image analysis system was conducted to study the characteristics of particle size and shape distribution along the debris channel. The image analysis of these field data showed that the median size (D50) of particles ranged from 0.41 to 27.71 m in the landslide area. Particle fractal dimension (D) obtained from the Number-size distribution ranged from 1.77 to 2.97 over the entire study area. Moreover, the evolution of D50 and D along the run-out path confirmed that the degree of cumulative rock fragmentation increased as the travel distance increased. Additionally, the particle roundness (R) ranged from 0.51 to 0.88 along the run-out path, which peaked twice during the motion of granular flow, once was in the entrainment area, and another was in the end of the deposition area. Rock scraping occurred in the entrainment area could increase the degree of rock grinding, and reshape coarse stones into smooth particles of large R values (larger roundness of particles could lead to longer spreading distance in a landslide event, due to the lower internal friction among particles). Based on analysis above, the rock scraping phenomena occurred between the source materials and entrainment materials were confirmed to influence the translation and spread of granular flows in landslides. [ABSTRACT FROM AUTHOR]

The paper proposes a methodology for quantitative landslide risk assessment for regional-scale analysis. Each component of risk, i.e., hazard, vulnerability, and consequence analysis, is quantitatively assessed. The developed landslide risk assessment methodology is tested in Kumluca watershed, in Bartın, Turkey. Geographic information systems and remote sensing techniques are used to create landslide factor maps, to obtain susceptibility maps, hazard maps, elements at risk, and risk maps. Susceptibility maps are obtained by using a logistic regression model while adopting a grid-based mapping unit. In addition to spatial probability of occurrence of damaging events, landslide hazard calculation requires the determination of the temporal probability. Precipitation triggers the majority of landslides in the study region. The critical rainfall thresholds were estimated by using antecedent rainfalls and landslide occurrence dates based on Gumble Distribution approach. The elements at risk are extracted from existing digital cadastral databases and the vulnerabilities are obtained by adopting some generalization approaches. To conclude, quantitative risk maps were produced on a continuous scale where numerical values indicate the distribution of risk including the annual probability of expected losses in TL per pixel and the annual probability of life loss per pixel for property and life, respectively. For the considered case study, it is found that the annual probability of property loss is the highest for the provincial highway and the provincial road. The property loss map highlights that the annual expected loss to power network is medium. The annual probability of life loss map illustrates that the region surrounded by Kumluca town, Kızıllar, and Zafer villages have medium and high annual expected loss of population values, respectively. [ABSTRACT FROM AUTHOR]

This paper presents results of recent studies on distribution and category of landslides in one section of the Sichuan–Tibet Highway, adjacent to the northern side of the Yarlu Tsangpo Grand Canyon, Tibet, Southwestern China. In the tectonic setting predominated by compression and strike-slipping, active faults are dominant and result in the genesis of the great alpine relief together with fluvial incision and unloading. In this section, with a distance of about 290 km between Ranwu and Lulang, 34 landslides occurred. Among them, the 12 large and super-large landslides comprise the most dangerous part of the highway system to road users over the past 50 years. The landslides usually occurred in slopes comprised of moraine with a large thickness, fluvio-pluvial and lacustrine deposits and fractured rocks. Based on the examination of the physical geography, structural geology, Quaternary geology, stratigraphy and petrography, this paper presents the temporal-spatial distribution of landslides along the section and classification of them into three types with respect to mechanism and composites of landslides. Each of the three types is presented by distinctive case examples. Type 1 is Yigong Landslide; type 2 includes Dongjiu Landslide group, 102 Landslide group, Suotong Landslide group, Songzong Landslide; and the type 3 is Layue Landslide. A binary landslide, which is seldom seen in nature and which occurred in the outlet of one creek under the integrative function of fluvial incision and road cut, is also presented. These are distributed in different parts of the area with characterized structural geology, topography and composites (gneiss and Quaternary deposits) with accumulative quantity between Suotong and Dongjiu. The most occurred with frequent and rapid translation, shallow shearing planes, various influential factors and unique triggering factors, and a variable period of reoccurrence with a tendency of increasing magnitude. In this region, six influential factors greatly contribute to their occurrence: (a) intensive neotectonic movements, (b) ongoing alpine canyon relief, (c) earthquakes, (d) heavy precipitation, (e) stream erosion, and (f) human activities, to a certain extent. Mostly, the latter four factors play major roles in triggering landslide occurrence. The earthquake causes the rock and soil to fracture and deform, and tends to be unstable, or cause earth-induced landslides. The heavy rainfall in monsoon seasons which saturates the soil and lower the shearing strength is mostly responsible for the occurrence of landslides. The stream erosion disturbs slope toes causing progressive failure. Road construction and deforestation decrease the natural slope stability. Comments and suggestions on the physical measures for remediation of landslides and safety of highways are also made. [ABSTRACT FROM AUTHOR]

Calculating the failure probability of a landslide is important in engineering related to geological process and geomorphological evolution. Strength parameters of a soil (i.e., cohesion and internal friction angle) are regarded as uncertain-but-bounded parameters. In this study, a new method is proposed for computing the landslide failure probability based on a convex set model and artificial neural network (ANN). In the new method, ANN is used to determine the limit state function of landslide stability, and the failure probability is determined using a simple iterative algorithm. The new method was applied to calculate the failure probability of the Gufenping landslide in Nanjiang, Sichuan, China. The results calculated using a Monte Carlo simulation (MCS) method confirmed that the new method accurately and quickly obtains the failure probability of a landslide. Additionally, compared with the two-dimensional calculation method, the one-dimensional analysis method overestimates the failure probability of the landslide. The results of single factor and global sensitivity analysis indicate that the average of internal friction angle is the main factor affecting the stability of the landslide. It is easy to calculate failure probability of landslides using the novel method than using the conventional methods. [ABSTRACT FROM AUTHOR]

Based on an analysis of displacement-monitoring data of Xintan landslide, China, it was discovered that the whole stability of large-scale colluvial landslides can be more accurately described by taking the displacement vector angle into account, and the stability trend of a slope can be evaluated and predicted using the displacement vector angle. This paper also further indicates that the monitored deformation vector angle can be divided into sliding deformation vector angle, plastic-deformation vector angle, compressive deformation vector angle and creep deformation vector angle in terms of the displacement properties of the slope. Through the analysis it is found that the displacement vector angle, for which there is no substitute, is an important parameter serving as an explicit criterion for the stability of the slope, and hence its significance in the prediction of landslides. It is also shown that as far as the displacement vector angle is concerned, there are different constituents and features in the different deformation stage of colluvial landslide. On the basis of these and using the principles of statistics, a discussion on the stability of the colluvial slopes is carried out in terms of the monitoring data of F-series points on Xintan slope. The analysis results coincided with the destabilized time and the sliding laws, thus demonstrating that the parameter of the displacement vector angle has to a certain extent, very important significance in the forecasting of landslides. [ABSTRACT FROM AUTHOR]

The evaluation of the success of soil bioengineering work is an issue still poorly addressed by the scientific community. Nevertheless, soil bioengineering techniques are increasingly used worldwide when mitigating the impact on the environment and the landscape is one, but not the only, goal of intervention. A tool to measure the success of soil bioengineering work, with reference to landslide stabilization, is presented in this paper: the index of ecological success (IES). The IES is based on the phytosociological analysis of vegetation and widens the potential applications of the ecological index of maturity (EIM), recently formulated by Giupponi et al. (Restor Ecol 23:635-644, 2015) to assess the degree of disturbance affecting a plant community. The IES compares the EIM values of the vegetation of an area affected by soil stabilization work with those of the expected vegetation at a precise time after completion of soil stabilization work, providing values ranging between 0 (maximum failure) and 1 (complete success). The IES was applied in two study areas located on two mountain slopes of the Southern Alps (Italy) which, as a result of landslides, were subject to soil bioengineering work aimed at slope stabilization. The results of these first two applications confirm the efficacy of the IES in evaluating the success of soil bioengineering work in mountain areas and bode well as to its future application. [ABSTRACT FROM AUTHOR]

The natural hazard assessment is hampered by many difficulties due to the complexity of the phenomenon and the need to manage simultaneously several natural and/or technological hazards. Such is the case of most unstable urban sites in Algeria. The paper presents a risk analysis study of landslides and their reactivation in Tigzirt coastal city, located in the north of Algeria, which is classified in a moderate seismic zone. The spatial techniques based on geographic information systems are used to assess landslide susceptibility and hazard. Two qualitative studies of landslide hazard assessment are conducted using parameters defining the Algerian landslides context. The hazard is evaluated by performing a combination of the landslide susceptibility and the urban density. Earthquake-induced landslide hazard is assessed taking into account the Algerian seismicity. The study led to determination and mapping of the hazard induced by Tigzirt landslides. [ABSTRACT FROM AUTHOR]

This paper presents the results of monitoring flysch formation shear wave velocities at varying conditions of water content by seismic interferometry. Studies were conducted on a section of the active Just-Tegoborze landslide in the southern region of Poland. The landslide is intersected by the state road no. 75, which has a high traffic density. Measurements of the seismic interferometry were made on the basis of the registration of a local high-frequency noise generated mostly by passing heavy vehicles. Measurements were carried out in three series on January, March and July in 2015. Seismic noise vibration was registered using Güralp CMG-6TD broadband seismometers. One of the seismic profiles was located along a geological engineering cross-section prepared from research boreholes data. One of the main results of the work was the sections of changes of shear wave velocity. The interpreted seismic boundaries made it possible to correlate them with the lithological ones. The trough-like shape of the bedrock boundary may be an effect of weathering processes developed in the zone consisting of weak hieroglyphic beds. It is also supposed to be one of the slip surfaces. The seismic sections of shear wave velocity allowed to analyse velocity variations between three measurement series and to compare them with expected water content in colluvium deposits. The presented results of the study confirmed the utility of seismic interferometry based on ambient noise registration in evaluating the behaviour of landslides in the Carpathian flysch formation. [ABSTRACT FROM AUTHOR]

Landslide hazard maps are often defined as reliable a posteriori, in accordance with the real landslides occurring from the time of the map production. However, to be useful for planning, a reliability judgment concerning the hazard mapping should be a priori, based on data uncertainty characterization, and must be driven by the knowledge of the slope instability mechanisms. The landslide hazard assessment, when based on the deterministic diagnosis of the processes, may really lead to really providing clues about how and why the slope could fail (landslide susceptibility) and, possibly, when (landslide hazard). Such deterministic assessment can be pursued only through the interpretation and the geo-hydro-mechanical modelling of the slope equilibrium. In practice, though, the landslide hazard assessment is still seldom dealt with slope modelling, in particular when it addresses intermediate to regional zoning. The paper firstly offers an overview of the key steps of a methodology called the multiscalar method for landslide mitigation, MMLM, which that is a methodological approach for the intermediate to regional landslide hazard assessment using the hydro-mechanical diagnoses of landsliding. The validation of the MMLM to the geologically complex outer sectors of the Southern Apennines (Daunia-Lucanian mountains; Italy) is also delineated, together with a practical approach to incorporate a reliability judgment in the landslide susceptibility/hazard mapping. [ABSTRACT FROM AUTHOR]

Background: Strong earthquakes are among the prime triggering factors of landslides, which may block rivers, forming landslide dams. Some of these dams may pose serious threats to people and property due to upstream inundation and downstream dam-breach flooding. Evaluating the stability and potential hazard of landslide dams is significant for the mitigation measures, but remains challenging. The 2008 Wenchuan earthquake ( M 7.9) in China triggered numerous landslides over a broad area, some of which dammed rivers, posing severe threats to downstream settlements. Our previous study created one of the most complete landslide dam inventories including detailed geomorphic parameters of 828 landslide dams induced by the Wenchuan earthquake. This paper presents the study of a number of representative landslide dams associated with the 2008 Wenchuan earthquake. Results: The coseismic landslides were classified into rock/debris avalanches, debris flows, rock/debris slides and rock falls. According to dam composition material and sedimentological features, landslide dams were categorized into three types: dams mainly composed of large boulders and blocks; dams composed of unconsolidated fine debris; and dams with partly intact rock strata at the base topped by large boulders and blocks or soil with rock fragments, showing two-layered or three-layered depositional structure. This classification is linked to the typology of damming landslides and considered to be a preliminary indicator of dam stability. In addition, dam stability also largely depends on valley morphometry as well as landslide runout distance and mechanism. The post-earthquake debris flow damming events induced by subsequent rainfalls are also introduced. It was found that there is still a large amount of loose sediment remaining on the slope, which may continue promoting heavy debris flows and dams in the coming years or decades. Conclusions: The classification of landslide dams proposed in this study can be used as a preliminary indicator of dam stability. More reliable assessment requires a geotechnical approach taking into account a variety of dynamic loading scenarios, and also relies on knowledge about the accurate dam and barrier-lake geometry. There is still a large amount of loose sediment remaining on the slopes, which may be reactivated and remobilized during the heavy post-earthquake rainstorms. Therefore, predicting the post-earthquake debris flows and evaluating their potential for damming rivers are still of great concern and remain as a main challenge. [ABSTRACT FROM AUTHOR]

Landslides are considered as one of the natural hazards responsible for casualties, damage of assets, and infrastructures. In many situations, collection of field data from remote places is difficult due to inaccessibility of landslide area. This paper examines landslide susceptibility in the Bukit Antarabangsa, Kuala Lumpur, to ease geographical studies, using image processing and multivariate statistical tools by reviewing the digital images using remote-sensing technique without any physical survey. We considered different pixel resolutions and report the effectiveness of using factor analysis, principal component analysis, linear discriminant analysis, and their hybridization. Eight types of databases for heavy, medium, and no landslide were created. The modeling works were carried out at 2 × 2, 4 × 4, 8 × 8, 16 × 16, 32 × 32, 64 × 64, 128 × 128, and 256 × 256 pixel resolutions. Results indicate 2 × 2 was optimal in both heavy and medium while 8 × 8 found to be ideal for no landslide region. Performance at different pixel resolutions was compared using receiver operating characteristic (ROC) curves, and average success of 87.36% was found. This simple yet robust system holds great potential for saving lives. [ABSTRACT FROM AUTHOR]

Of the natural hazards in Turkey, landslides are the second most devastating in terms of socio-economic losses, with the majority of landslides occurring in the Eastern Black Sea Region. The aim of this study is to use a statistical approach to carry out a landslide susceptibility assessment in one area at great risk from landslides: the Sera River Basin located in the Eastern Black Sea Region. This paper applies a multivariate statistical approach in the form of a logistics regression model to explore the probability distribution of future landslides in the region. The model attempts to find the best fitting function to describe the relationship between the dependent variable, here the presence or absence of landslides in a region and a set of independent parameters contributing to the occurrence of landslides. The dependent variable (0 for the absence of landslides and 1 for the presence of landslides) was generated using landslide data retrieved from an existing database and expert opinion. The database has information on a few landslides in the region, but is not extensive or complete, and thus unlike those normally used for research. Slope, angle, relief, the natural drainage network (including distance to rivers and the watershed index) and lithology were used as independent parameters in this study. The effect of each parameter was assessed using the corresponding coefficient in the logistic regression function. The results showed that the natural drainage network plays a significant role in determining landslide occurrence and distribution. Landslide susceptibility was evaluated using a predicted map of probability. Zones with high and medium susceptibility to landslides make up 38.8 % of the study area and are located mostly south of the Sera River Basin and along streams. [ABSTRACT FROM AUTHOR]

Debris flows can be extremely destructive because they can increase in magnitude via progressive entrainment. In this paper, a total of 18 landslide-type debris flows and 268 channelized debris flows in Wenchuan earthquake and Taiwan region, as well as other regions were collected to analyze the entrainment rate of debris flows in each triggering condition. Results show that there is a power relationship between volume of initial triggered mass and final deposited debris for landslide type debris flow. The debris flows during 2008 and 2013 in Wenchuan earthquake-region have smaller entrainment rate than that from 2001 t0 2009 in Taiwan. The entrainment rate of debris flow events from 2001 to 2009 in Taiwan shows a decaying tendency as elapsed time. Comparison of the entrainment rate in the two earthquake-hit regions with other regions proves that entrainment rate has a close relation with major sediment availability and secondary rainstorm conditions. [ABSTRACT FROM AUTHOR]

The present paper reports on the activities conducted since 2008, within the International Programme on Landslides (IPL), for the realisation of the Geological and Landslides Museum of Civita di Bagnoregio (Central Italy) (IPL project 106-1). The town of Civita di Bagnoregio (Latium Region, Central Italy), located at the border of the ancient Volsini volcano and placed on a high tuff peak that rests on fragile clay, is a stunning case where the human presence has tried for centuries to hinder the natural degradation of the cliff. It is a paradigm of the men who tries to survive in a hostile environment with an incomparable beauty and nature that wants to take its course dismantling and eroding all reliefs. The Geological and Landslides Museum is a scientific institution introducing visitors to the fundamentals of landslide science, describing the site evolution through the relationship between human being and geomorphological processes in the last millennium and, finally, introducing to the 'real museum' that are the ongoing landslides on the cliff and valleys. The visitors will find in the museum many scenic spots that are describing the evolution of territory but, in the meantime, they are encouraged to visit the site and to touch by hand the various geomorphological features of the site. The museum also seeks to develop a culture of resilience to landslide disasters, promoting the site as a 'geomorphological park' to study and test innovative monitoring tools, for the benefit of scientific community. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to exploit information obtained from satellite SAR data to detect and monitor instability phenomena affecting hilly and scarcely urbanized areas, overtaking some of the restrictions due to the presence of thick vegetation. To this end, phase and amplitude analyses of COSMO-SkyMed SAR data were carried out on two landslides located in the North-Eastern Italian pre-Alps: Cischele roto-translational slide and Val Maso rotational slide-earth flow. In the first case, the careful choice of processing parameters allowed to evaluate landslide displacement fields considering the phase difference between SAR acquisitions. In the second case, the speed of movement and the deep changes in morphology and vegetation induced by the landslide did not allow to apply DInSAR techniques; in this case the variation in the amplitude between SAR acquisitions allowed to detect the area affected by the instability. Obtained results show that methods and techniques to analyse satellite SAR data could be further refined in order to provide useful tools for landslide mapping and monitoring. [ABSTRACT FROM AUTHOR]

In Slovenia, rainfall-induced landslides lead to considerable damages, even causing human losses. In order to reduce the impact of this kind of landslide, several researchers analyzed rainfall-induced landslides in this country, but to date, no rainfall thresholds have been developed for a landslide warning system at national scale. In this paper, the definition of rainfall thresholds for rainfall-induced landslides in Slovenia is presented. The thresholds have been calculated by collecting approximately 900 landslide data and the relative rainfall amounts, which have been collected from 41 rain gauges. To define the thresholds, an existing procedure characterized by a high degree of objectiveness has been used. This approach is based on a software that was developed for a test site with very different characteristics (Tuscany, central Italy). At first, a single national threshold has been defined; subsequently, the country was divided into four zones, on the basis of the major river basins. The effectiveness of the thresholds has been verified by the use of several statistical parameters and it resulted in quite good performances, even if with some uncertainties, probably due to the quality of the available data. Besides the setting of a threshold system, usable for civil protection purposes at national scale, an additional outcome of this work was the possibility of applying, with good results, a methodology defined for another region, therefore testing its degree of exportability in different settings. [ABSTRACT FROM AUTHOR]

The denudation of young reliefs prone to landslides can have severe consequences for society and the environment. However, landslide databases and the additional information (landslide type, date and triggering factors) necessary to deal with landslide hazard assessment and the development of effective and reliable landslide warning systems are usually scarce or non-existent. In this way, by taking into account the date of landslide events and by expanding the analysis of cumulative rainfall from these dates to a broader time period that includes the days or months leading up to a landslide, the corresponding triggering rainfall threshold can be assessed more accurately. In this paper, a methodology based on a partial duration series analysis applied to rainfall variables allows the possibility to better understand precipitation patterns. Another advantage of analysing precipitation variables within a broader time period is the ability to identify greater accuracy rainfall anomalies such as extreme rainfalls with their return period related to a low number of dated landslide events (in this case, 20 landslide events). The landslide spatial distribution within a regional area requires the processing and analysis of data from multiple long-term historical daily rainfall records from different rainfall gauges, which notably increase the number of calculations to be dealt with. To overcome this inconvenience, these processes were streamlined by using macro-automation. Additionally, different rainfall durations can be interactively identified from graphical outputs that show anomalies on more than one rainfall variable after applying this methodology. Among these rainfall variables, the antecedent accumulated rainfall (A1) was found to be the most suitable to apply the occurrence probability analysis. When compared to other variables, the return period values of A1 were determined to be conservative, neither too high nor too low. Using this approach, the return period curve was shown to be an important graphic object in detecting uncommon rainfalls that are contemporaneous or previous to landslides. The relevant findings of this research show a power-law trend with α = 88.005 and β = 0.69 in the correlation of intensity and duration associated with antecedent cumulative rainfall (A1) anomalies. The mean return period for these anomalies resulted in 12.4 years, while for 50 % of the landslides, the recurrence interval was estimated in less than or equal to 3.6 years. In addition, significant differences were found between catalogued slope-cut failures and natural landslides. Moreover, differences were also found between simplified types of natural landslides. [ABSTRACT FROM AUTHOR]

Intensity–duration rainfall thresholds are commonly used in regional-scale landslide warning systems. In this manuscript, 3D thresholds are defined also considering the mean rainfall amount fallen in each alert zone (MeAR, mean areal rainfall) in Emilia Romagna region (Northern Italy). In the proposed 3D approach, thresholds are represented by a plane instead of a line, and the third dimension allows to indirectly account for the influence of complex rainfall patterns. MeAR values are calculated according to different time periods ranging from 7 to 30 days, and all threshold parameters are calibrated independently for the 8 alert zones in which the region is divided. The approach was validated and compared with classical intensity–duration thresholds, finding that the 3D threshold may be used to get better performances, especially in terms of a consistent reduction of false alarms:− 20 to − 86%, depending on the alert zone and the selected MeAR duration. These results open new encouraging perspectives for the development of the regional warning system that is operated in the study area. [ABSTRACT FROM AUTHOR]

Wenchuan earthquake occurred 7 years ago, and more than 100 landslides and rock avalanches were triggered by the earthquake in Gaochuan river watershed, in Southwest China, including the Daguangbao landslide, which is the largest one triggered by Wenchuan earthquake, having a volume around 1.15 billion m. The massive landslide deposits provided uncountable material source for debris flow in the study area, resulting in 25 debris flow events occurred in the past 6 years (2009-2014). The purpose of this paper is to analyze the variability in the rainfall threshold for debris flow after the earthquake in the study area. Results suggest that the critical rainfall threshold is closely related to the rainfall intensity ( I) and the antecedent accumulated precipitation ( P). There was a sudden drop of the rainfall threshold when the earthquake happened. During the 6 years, the rainfall threshold value kept increasing gradually in a linear trend. However, it is now still much lower than the original rainfall threshold prior to the earthquake. The threshold is expected to reach the original level around 2022 based on the analysis of existing data. Our study indicates that the increase of rainfall threshold is related to the decrease of sediments. And there are still lots of loose deposits in the gullies. Thus, the debris flow can still happen in a high possibility in the next few years. [ABSTRACT FROM AUTHOR]

The present paper aims at to produce the building vulnerability and its spatial distribution in mountainous regions of the Nilgiris District in the Western Ghats, India. The landslide-susceptible areas were identified based on the existing landslide-susceptible maps. The landslide-prone slope was identified based on the historical and recent landslide information's collected from various authenticated sources as well as the field investigations made on the recent landslides. The high-to-severe landslide hazard-prone areas were selected for the present study of building vulnerability analysis. The areas were divided into ten segments based on the landslide inventory, built-up areas, and transportation corridors in the vicinity of landslide locations. Building foot print map was prepared for each segments using ArcGIS software visual interpretation for 1627 buildings and infrastructures. Different thematic layers viz, building type/material, surrounding wall, sloping side details, warning, and number of floors which contribute to landslide vulnerability in vector formats are used for the present study. Using the formula proposed by Papathoma-Köhle et al. (Nat Hazards Earth Syst Sci 7:765-779, ) the vulnerability score were calculated by scripting in ArcGIS software. Based on the vulnerability score, the buildings were grouped under three categories viz, low, medium, and high vulnerability. The spatial distribution of vulnerability of buildings was prepared and presented. The present study can be useful data for preparation of regional landuse plan as well as evacuation plans and warning systems to safeguard measure for population living in the vulnerable buildings in The Nilgiris District of Western Ghats in India. [ABSTRACT FROM AUTHOR]

Except for simple sliding motions, the stability of a slope does not depend only on the resistance of the basal failure surface. It is affected by the internal distortion of the moving mass, which plays an important role on the stability and post-failure behaviour of a landslide. The paper examines the stability conditions and the post-failure behaviour of a compound landslide whose geometry is inspired by one of the representative cross-sections of Vajont landslide. The brittleness of the mobilized rock mass was described by a strain-softening Mohr-Coulomb model, whose parameters were derived from previous contributions. The analysis was performed by means of a MPM computer code, which is capable of modelling the whole instability procedure in a unified calculation. The gravity action has been applied to initialize the stress state. This step mobilizes part of the strength along a shearing band located just above the kink of the basal surface, leading to the formation a kinematically admissible mechanism. The overall instability is triggered by an increase of water level. The increase of pore water pressures reduces the effective stresses within the slope and it leads to a progressive failure mechanism developing along an internal shearing band which controls the stability of the compound slope. The effect of the basal shearing resistance has been analysed during the post-failure stage. If no shearing strength is considered (as predicted by a thermal pressurization analysis), the model predicts a response similar to actual observations, namely a maximum sliding velocity of 25 m/s and a run-out close to 500 m. [ABSTRACT FROM AUTHOR]

Inclinometer and piezometer measurements have been carried out since 2005 in a slow active earthflow in a clay shale formation of the Italian Southern Apennines. Previous studies outlined the main geometrical and kinematic features of the landslide and the pore pressure response to rainfall. Displacement rates seem to depend on the hydrological conditions as suggested by their seasonal variations. The availability of long time series of data, in some periods recorded in continuum, allows the use of a data mining approach to evaluate the relations among displacement rates in different points of the landslide, and between displacement rates and rainfall. To define such relations, the evolutionary modelling technique EPRMOGA, based on a genetic algorithm, has been used in this paper. The results give a deeper insight into the landslide behaviour on the one hand and, on the other hand, show the reliability of the technique, also in building up management scenarios. In particular, the results show that the landslide displacement rates in different points of the slip surface, although characterized by different values, are linearly dependent and thus have the same time trend, supporting the hypothesis of a constant soil discharge mechanism of movement. Piezometric data in single points cannot be used, in the considered case, to forecast displacements. The obtained relations allow to quantify the displacement rate variations due to contemporary rainfall. The influence of past rainfall is shown to decrease exponentially with temporal distance. Furthermore, the EPRMOGA simulations seem to confirm that there are no other dominant causes, besides rainfall, responsible of displacement rate variations in time. [ABSTRACT FROM AUTHOR]