ALBERT

Description: Preparation of reliable landslide hazard and risk maps is crucial for hazard mitigation and risk management. In recent years, various approaches have been developed for quantitative assessment of landslide hazard and risk. However, possibly due to the lack of new data, very few of these hazard and risk maps were updated after their first generation. In this study, aiming at an ongoing assessment, a novel approach for updating landslide hazard and risk maps based on Persistent Scatterer Interferometry (PSI) is introduced. The study was performed in the Arno River basin (central Italy) where most mass movements are slow-moving landslides which are properly within the detection precision of PSI point targets. In the Arno River basin, the preliminary hazard and risk assessment was performed by Catani et al. (Landslides 2:329–342, 2005) using datasets prior to 2002. In this study, the previous hazard and risk maps were updated using PSI point targets processed from 4 years (2003–2006) of RADARSAT images. Landslide hazard and risk maps for five temporal predictions of 2, 5, 10, 20 and 30 years were updated with the exposure of losses estimated in Euro (€). In particular, the result shows that in 30 years a potential loss of approximate €3.22 billion is expected due to these slow-moving landslides detected by PSI point targets.

Description: The present paper illustrates the results of an integrated study of a large landslide located on the southern slope of Mount la Civita (Molise, Southern Apennine), an E–W elongated, SSE dipping and 890-m-high monocline carbonate ridge. The upper part of the slope affected by the landslide is largely controlled by strata attitude while its basal part is marked by a strike–slip fault causing the tectonic juxtaposition of the carbonate successions against predominantly clayey flysch units. An integrated study, including geological, geomorphological and geotechnical investigations, was carried out to determine the features of the landslide and to plan further investigation and monitoring. In particular, from 2002 to 2004, Differential Global Positioning System monitoring and core drillings, coupled with inclinometer measurements, were carried out to determine the landslide’s kinematics, extent, depth to the surface of rupture and rates of movement. Inclinometer data revealed the presence of the rupture surface at a depth of about 20 m. DGPS monitoring allowed rates of movement up to several tens of centimetres per year to be recorded. The nearby village of Civitanova del Sannio can still be considered at risk due to the landslide, as recent remedial works, consisting mainly of very shallow re-shaping of the slope by blasting and partial filling of trenches, did not succeed in stopping its movement.

Description: The objective of this paper is to develop an efficient analytical method for assessing the vulnerability of low-rise reinforced concrete buildings subjected to seismically induced slow-moving earth slides. Vulnerability is defined in terms of probabilistic fragility curves, which describe the probability of exceeding a certain limit state of the building, on a given slope, versus the Peak Horizontal Ground Acceleration (PHGA) at the assumed “seismic bedrock”, allowing for the quantification of various sources of uncertainty. The proposed method is based on a two-step, uncoupled approach. In the first step, the differential permanent landslide displacements at the building’s foundation level are estimated using a dynamic non-linear finite difference slope model. In the second step, the calculated differential permanent displacements are statically imposed at the foundation level to assess the building’s response to differing permanent seismic ground displacements using a finite element code. Structural limit states are defined in terms of threshold values of strains for the reinforced concrete structural components. The method is applied to typical low-rise reinforced concrete frame buildings on shallow foundations with varying strength and stiffness characteristics (isolated footings and continuous slab foundation), standing near the crest of a relatively slow-moving earth slide. Two different slope models are selected representing a cohesive and a purely frictional soil material. The paper describes the method and the derived fragility curves for the selected building and slope typologies that could be used in quantitative risk assessment studies at site-specific and local scales.

Description: Semi-empirical models based on Newmark’s sliding block permit the estimation of expected co-seismic displacements in relation to one or more parameters which characterize the ground motion that theoretically caused them. Taking this into consideration, a regression analysis, based on a double-phase viscoplastic (DPV) model, was developed using 96 Italian ground motion accelerograms for a total of 1,448 combinations obtained for different parametric conditions of the indefinite slope model. Repeated stability analysis, performed by means of the DPV model, allows for the assessment of the seismic instability of a slope in relation to different reached behaviour levels, as well as seismically induced permanent displacements. At these behaviour levels, co-seismic increases and possible subsequent decreases of viscoplastic shear strengths are associated. This implies that the post-seismic persistent mobility (collapse) of the slope can be obtained from the computation. On the other hand, coherently with the increasing of shear resistances during fast sliding displacements in clay soils, the seismic-forced displacements result substantially lower than corresponding values obtained by means of the rigorous Newmark’s sliding block. In addition, in relation to some seismic ground motion parameters, regression and functional border and separation curves were obtained with the aim of providing an expeditious seismic slope stability evaluation in reference to the co-seismic and post-seismic behaviour of clayey slopes. Regarding this, the real behaviour of two historical landslide events is discussed in the light of the results of the regression analysis outlined in this work.

Description: Landslide dams in mountainous areas are quite common. Typically, intense rainfalls can induce upstream flows along the sloping channel, which greatly affects the stability and failure modes of landslide dams. If a series of landslide dams are sequentially collapsed by an incoming mountain torrent (induced by intense rainfall), large debris flows can be formed in a short period of time. This also amplifies the magnitude of the debris flows along the flow direction. The catastrophic debris flows, which occurred in Zhouqu, China on August 8, 2010, were indeed caused by intense rainfall and the upstream cascading failure of landslide dams along the gullies. Experimental tests were conducted in a sloping channel to understand the dynamic process of cascading landslide dam failures and their effect on flow scale amplification. Similar to the Zhouqu conditions, the modeled landslide dams were distributed along a sloping channel and breached by different upstream flows. For each experiment, the front flows were sampled, the entrained grain sizes were analyzed, and the front discharge along the channel was measured. The results of these experiments show that landslide dams occurring along the channel can be destroyed by both high and low discharge flows, although the mechanisms are quite different for the two flow types. Regardless of flow type, the magnitude of the flows significantly increases after a cascading failure of landslide dams, resulting in an increase in both the diameter and the entrained coarse particles percentage.

Description: Landslides are widespread along the north-western coast of the Island of Malta and are strictly linked to the structural setting. Exemplary cases of rock spreading and block sliding phenomena characterise this stretch of coast. They are favoured by the overposition of two different geological units widely outcropping there, the Blue Clay Formation and the Upper Coralline Limestone Formation. The latter forms a wide plateau, bordered by vertical cliffs. At the foot of the cliffs, clayey terrains crop out and develop gentle slopes covered by large blocks detached and moved by rock spreading and block sliding phenomena. These mass movements are favoured by the fragile behaviour of limestones, which cap clays, otherwise characterised by visco-plastic properties. In order to investigate the kinematics and the evolution of these types of coastal landslides, a multidisciplinary and multitechnical approach was applied on a study site, named Il-Prajjet, which provides a spectacular case of rock spreading evolving into block sliding. This paper illustrates the results achieved by means of different engineering geological and geophysical techniques allied with traditional detailed geomorphological survey and mapping. In particular, the surface displacements of the landslides were determined using long-term GPS observations, acquired approximately every 6 months, over a 4.5-year period. A network of GPS benchmarks were distributed on the edge of a limestone plateau affected by rock spreading and on a series of displaced blocks making up a large block slide, finally enabling the definition of the state of activity and the rates of movement to be performed. In addition, the results deriving from two continuous fissurimeters more recently installed at the edge of two persistent joints over the block sliding area are outlined, with reference to the correlation between variations of crack apertures and precipitation input. In order to identify main structural discontinuities and to reconstruct variability of underground surface contact between clays and overlying limestones, Resistivity Tomography profiles and GPR investigations were carried out. Finally, the results obtained by combining the outputs of geophysical surveys and different field monitoring activities can be considered a first step on which numerical models can be developed and validated, in order to assess landslide hazard and risk of this stretch of Maltese coastline.

Description: The Faroe Islands in the North Atlantic Ocean are susceptible to flow-type landslides in coarse-grained highly organic colluvium. Following several hazardous debris avalanche events, research work has been initiated to quantify landslide risk. A central task in this work is to predict landslide runout behavior. From numerical simulation of four debris avalanches, this study provides a first screening of which rheology and appertaining input parameters best predict runout behavior of debris avalanches in the Faroe Islands. Three rheologies (frictional, Voellmy, and Bingham) are selected and used for individual back analysis of the events in the numerical models BING and DAN3D. A best fit rheology is selected from comparing predicted and observed landslide runout behavior. General back analysis to identify the optimal input parameters for the chosen rheology is performed by cross validation, where each debris avalanche is modeled with input parameters from the three other events. Optimal input parameters are found from the model run producing the most accurate runout length and velocity. The Bingham is selected as the best fit rheology, a result differing from similar studies of coarse-grained landslides. A reason for why particularly the frictional rheology proves unsuitable is its tendency to produce too long runout lengths of the low-weight runout material, a result showing important limitations for using the frictional rheology in DAN3D. Optimal Bingham input parameters are τ y  = 980 Pa and μ b  = 117 Pa/s. However, future studies performed in 2D models are needed for precise parameterization before results can be used for landslide risk assessment.

Description: In the framework of the European Soil Thematic Strategy and the associated proposal of a Framework Directive on the protection and sustainable use of soil, landslides were recognised as a soil threat requiring specific strategies for priority area identification, spatial hazard assessment and management. This contribution outlines the general specifications for nested, Tier-based geographical landslide zonings at small spatial scales to identify priority areas susceptible to landslides (Tier 1) and to perform quantitative susceptibility evaluations within these (Tier 2). A heuristic, synoptic-scale Tier 1 assessment exploiting a reduced set of geoenvironmental factors derived from common pan-European data sources is proposed for the European Union and adjacent countries. Evaluation of the susceptibility estimate with national-level landslide inventory data suggests that a zonation of Europe according to, e.g. morphology and climate, and performing separate susceptibility assessments per zone could give more reliable results. To improve the Tier 1 assessment, a geomorphological terrain zoning and landslide typology differentiation are then applied for France. A multivariate landslide susceptibility assessment using additional information on landslide conditioning and triggering factors, together with a historical catalogue of landslides, is proposed for Tier 2 analysis. An approach is tested for priority areas in Italy using small administrative mapping units, allowing for relating socioeconomic census data with landslide susceptibility, which is mandatory for decision making regarding the adoption of landslide prevention and mitigation measures. The paper concludes with recommendations on further work to harmonise European landslide susceptibility assessments in the context of the European Soil Thematic Strategy.

Description: Rainfall intensity–duration (ID) thresholds are commonly used to predict the temporal occurrence of debris flows and shallow landslides. Typically, thresholds are subjectively defined as the upper limit of peak rainstorm intensities that do not produce debris flows and landslides, or as the lower limit of peak rainstorm intensities that initiate debris flows and landslides. In addition, peak rainstorm intensities are often used to define thresholds, as data regarding the precise timing of debris flows and associated rainfall intensities are usually not available, and rainfall characteristics are often estimated from distant gauging locations. Here, we attempt to improve the performance of existing threshold-based predictions of post-fire debris-flow occurrence by utilizing data on the precise timing of debris flows relative to rainfall intensity, and develop an objective method to define the threshold intensities. We objectively defined the thresholds by maximizing the number of correct predictions of debris flow occurrence while minimizing the rate of both Type I (false positive) and Type II (false negative) errors. We identified that (1) there were statistically significant differences between peak storm and triggering intensities, (2) the objectively defined threshold model presents a better balance between predictive success, false alarms and failed alarms than previous subjectively defined thresholds, (3) thresholds based on measurements of rainfall intensity over shorter duration (≤60 min) are better predictors of post-fire debris-flow initiation than longer duration thresholds, and (4) the objectively defined thresholds were exceeded prior to the recorded time of debris flow at frequencies similar to or better than subjective thresholds. Our findings highlight the need to better constrain the timing and processes of initiation of landslides and debris flows for future threshold studies. In addition, the methods used to define rainfall thresholds in this study represent a computationally simple means of deriving critical values for other studies of nonlinear phenomena characterized by thresholds.

Description: The UK is a country with limited direct experience of natural disasters. Whilst landslide losses are not negligible and fatalities are rare, accounts are under-reported. Financial losses from landslides are poorly understood but likely to be considerably in excess of £10 million per year. As a result, a strategic management framework has evolved based upon small, low-impact events punctuated by occasional larger events or larger landslides affecting urban areas. We present an overview of the different landslide management mechanisms in the UK and discuss them in context of cases studies to explore their effectiveness. We conclude with three issues that may have implications for landslide management in the UK and other ‘ low-risk ’ countries. Firstly, the evidence base by which landslide hazards and risks are measured is insufficient and limitations in existing information need to be better understood. Secondly, existing guidance on strategic and responsive management needs to be assessed for its fitness for purpose. Thirdly, we encourage debate about the importance of near misses .

Description: The western part of the Argentera–Mercantour massif (French Alps) hosts very large currently active landslides responsible of many disorders and risks to the highly touristic valleys of the Mercantour National Park and skiing resorts. A regional scale mapping of gravitational deformations has been compared to the main geo-structures of the massif. A relative chronology of the events has been established and locally compared to absolute 10 Be dating obtained from previous studies. Two types of large slope destabilisations were identified as follows: deep-seated landslides (DSL) that correspond to rock volumes bounded by a failure surface, and deep-seated gravitational slope deformations (DSGSD) defined as large sagging zones including gravitation landforms such as trenches and scarps or counterscarps. Gravitational landforms are mainly collinear to major N140°E and N020°E tectonic faults, and the most developed DSGSD are located in areas where the slope direction is comparable to the orientation of faults. DSL are mostly included within DSGSD zones and located at the slopes foot. Most of DSL followed a similar failure evolution process according to postglacial over steepened topographies and resulting from a progressive failure growing from the foot to the top of the DSGSD that lasts over a 10 ky time period. This massif-scale approach shows that large-scale DSGSD had a peak of activity from the end of the last deglaciation, to approximately 7000 years bp . Both morphologic and tectonic controls can be invoked to explain the gravitational behaviour of the massif slopes.

Description: This study focused on the landslide case at Su-Hua Highway 115.9k, Taiwan. A preliminary investigation was conducted on geomorphologic features change and landslide mechanisms using digital elevation models, geographical maps, and remote sensing images at different times in conjunction with geological surveys and analysis results. Using the results of geological surveys and physical model experiments, we constructed a discrete element method to simulate the process of landslide movement. The results revealed deformation in the metamorphic rock slopes upstream of 115.9k. The slopes around the erosion gully upstream presented visible slope toes cutting and tension cracks at the crest as well as unstable rock masses. According to the results of numerical simulation for typhoon Megi event, intense rains could induce slippage in the rock debris/masses in the source area, initially at a speed of 5–20 m/s. Subsequently, steeper terrain could cause the rock debris/masses to accelerate to form a high-speed (〉30 m/s) debris slide quickly moving downstream to form an alluvial fan downstream by the sea.

Description: The initiation of loess landslides is a common engineering problem during the construction of the expressway or other engineering works in the Loess Plateau of China. The engineers and researchers should devote themselves to the prevention of the initiation of loess landslides. This study focused on a loess landslide which was induced during the construction of an expressway in Shanxi Province of China. The stabilities of the loess hillside slope before and after excavation were analyzed using limit equilibrium analysis method and the strength reduction finite element method, respectively. The analysis results indicated that the loess hillside slope, before excavation, was stable under both natural state and rainfall conditions. The collapse of the loess hillside slope, or the initiation of loess landslides, after having been excavated, was induced by excavation and rainfall. The integrated stabilization method including four parts was used to stabilize the loess landslide. The four parts were a reinforced concrete piles row, a rubble concrete retaining wall, alteration of slope geometry, and interception and drainage of water. The initiation of the loess landslide might be evitable if it was given enough attention before excavation; thus, the problem of loess landslides should be paid big attention during the survey and design of the engineering works, not only during the construction.

Description: Earthquakes in mountainous areas may produce many landslides that involve abundant snow, but few observations have been made of these hazardous phenomena. The 12 March 2011 north Nagano Prefecture earthquake (M JMA 6.7) occurred in a mountainous part of Japan that typically has an annual snow cover of more than 2 m, and it induced many snowy landslides. Some of these traveled relatively long distances. We examined the snowy Tatsunokuchi landslide to reconstruct the landsliding processes over deep snow. We infer that the Tatsunokuchi landslide occurred by collapse of a rock debris mass of 5 × 10 4  m 3 that plunged into the abundant snow, forming a mixture of snow and rock debris, which then traveled on top of the snow. Later, the displaced mass included a large amount of snow which was pushed forward at the front and to the sides. The velocity of the landslide was estimated to be approximately 14 m/s. It appears that the displaced mass, having only a small proportion of rock debris, had a low enough density to travel easily on top of the snow. Our observations suggest that there was much liquid water at the base of the displaced mass shortly after the event. Our results suggest that landslides may damage wider areas than expected if they travel over deep snow.

Description: Identification of landslides and production of landslide susceptibility maps are crucial steps that can help planners, local administrations, and decision makers in disaster planning. Accuracy of the landslide susceptibility maps is important for reducing the losses of life and property. Models used for landslide susceptibility mapping require a combination of various factors describing features of the terrain and meteorological conditions. Many algorithms have been developed and applied in the literature to increase the accuracy of landslide susceptibility maps. In recent years, geographic information system-based multi-criteria decision analyses (MCDA) and support vector regression (SVR) have been successfully applied in the production of landslide susceptibility maps. In this study, the MCDA and SVR methods were employed to assess the shallow landslide susceptibility of Trabzon province (NE Turkey) using lithology, slope, land cover, aspect, topographic wetness index, drainage density, slope length, elevation, and distance to road as input data. Performances of the methods were compared with that of widely used logistic regression model using ROC and success rate curves. Results showed that the MCDA and SVR outperformed the conventional logistic regression method in the mapping of shallow landslides. Therefore, multi-criteria decision method and support vector regression were employed to determine potential landslide zones in the study area.

Description: Four statistical techniques for modelling landslide susceptibility were compared: multiple logistic regression (MLR), multivariate adaptive regression splines (MARS), classification and regression trees (CART), and maximum entropy (MAXENT). According to the literature, MARS and MAXENT have never been used in landslide susceptibility modelling, and CART has been used only twice. Twenty independent variables were used as predictors, including lithology as a categorical variable. Two sets of random samples were used, for a total of 90 model replicates (with and without lithology, and with different proportions of positive and negative data). The model performance was evaluated using the area under the receiver operating characteristic curve (AUC) statistic. The main results are (a) the inclusion of lithology improves the model performance; (b) the best AUC values for single models are MLR (0.76), MARS (0.76), CART (0.77), and MAXENT (0.78); (c) a smaller amount of negative data provides better results; (d) the models with the highest prediction capability are obtained with MAXENT and CART; and (e) the combination of different models is a way to evaluate the model reliability. We further discuss some key issues in landslide modelling, including the influence of the various methods that we used, the sample size, and the random replicate procedures.

Description: The First Meeting of ICL Landslides in Cold Regions Network and First Symposium on Landslides in Cold Regions were held in Harbin, China on 23–27 July 2012. The main goal of the network is to promote cooperation of scientists studying landslides in the permafrost regions and regions with extreme weather conditions. It will support joint comprehensive investigations carried out by geographers, geologists, geocryologists, and meteorologists from different countries and regions, landslide mechanisms study, distinguishing of landforms, provision of landslide hazard assessment, and elaboration of early warning systems. Such cooperation will enhance our understanding of hazardous phenomena in cold regions and the safety of people living there, their property, and infrastructure. This meeting included an international symposium “Landslide in Cold Regions,” 2-day field trip, discussion, and approval of the “Constitution of ICL Landslides in Cold Regions Network,” “2012–2016 Action Plan of ICL Landslides in Cold Regions Network,” and “Declaration of the First Meeting of ICL Landslides in Cold Regions Network.”

Description: A granular body may deform in a continuous fashion such that the solid particles remain in close contact. Previous research works have always used the frictional Coulomb-like continuum treatment for analyzing granular bodies. However, this approach is only applicable for quasi-static conditions and cannot capture the complicated granular contact behavior of solid particles inside a failing granular body. This paper applies a revised Savage–Hutter equation to model granular flows moving down a confined, sloping channel. The Coulomb contact friction law is modified to consider the effect of the shear rate inside a granular body. This new method also considers the confinement effect of a sloping channel on granular flow mobility. The derived depth-averaged equations of motion bear a resemblance to nonlinear shallow-water wave equations. Results computed using the derived equations are compared with measurements from flume model tests, and consistency is found between the two.

Description: The kinematics and internal deformation of a failure mass during the flow-like moving off a slope were monitored and quantified with the particle flow method in this study. Two kinds of cases were investigated, noncohesive and cohesive granular slopes. Three different internal friction angles and cohesive strengths were considered to systematically investigate their effect on the kinematics and internal deformation of the failure mass. We analyzed the movement within the failure mass and concluded that the mass moves downwards in an undulating pattern. The slope surface topography changes from a straight line to curved lines with slope breaks in a convex geometry. In addition, dilatation within the failure mass, which deforms internally and heterogeneously, is strongly dependent on its mechanical properties. A larger mass moves downslope, and the mass moves faster and further in the model with lower internal friction and cohesion. The internal friction and cohesion have a positive impact on porosity and two-dimensional (or volumetric in 3D) strain within the failure mass.

Description: Landslide susceptibility (LS) assessment by indirect approaches presents some limitations due to (1) the tendency to simplify the environmental factors (i.e., variables) and (2) the assumptions that landslides occur under the same combination of variables for a study site. Recently, some authors have discussed the interest to introduce expert knowledge in the indirect approaches in order to improve the quality of indirect LS maps. However, if the results are reliable, the procedures used seem fastidious and a very good knowledge of the study site is essential. The objectives of this paper are to discuss a methodology to introduce the expert knowledge in the indirect mapping process. After the definition of the expert rules associated to three landslide types, several indirect LS maps are produced by two indirect exploratory approaches, based on fuzzy set theory and on a modification of a bivariate method called expert weight of evidence. Then, the indirect LS maps are confronted to a landslide inventory and a LS map produced by a direct approach. The analyses indicate that the methodology used to introduce the expert rules in the mapping process increases the predictive power of indirect LS map. Finally, some indications about advantages and drawbacks of each approach are given to help the geoscientist to introduce his expert knowledge in the landslide susceptibility mapping process.

Description: International Consortium on Landslides (ICL) Adriatic-Balkan Network was established in January 2012 as one of eight regional and thematic ICL networks to promote activities of the International Consortium on Landslides and the International Programme on Landslides. This paper presents the annual report of the ICL Adriatic-Balkan Network for the year 2012. The main activity of the regional network was to complete an overview of publicly available data and sources about landslides in the region, scientific and professional practices related to evaluation and mitigation of landslide hazard, as well as related legislative framework. Recommendations for the discussion and endorsement in the course of the ICL Adriatic-Balkan Network activities will be derived from the analysis of strengths, weaknesses, opportunities, and threats related to landslide issues which are present at the national level in Croatia, Slovenia, and Serbia and at the regional level. Discussion and endorsement of the recommendations are planned as a further activity which will be held in March 2013 in Zagreb (Croatia), during the planned first regional symposium on landslides in the Adriatic-Balkan Region.

Description: Catastrophic deep-seated rock slope failures (RSFs; e.g., rock avalanches) can be particularly useful proxies for fault rupture and strong ground motion, and currently represent an underappreciated hazard of earthquakes in New Zealand. This study presents observations of the previously undescribed Cascade rock avalanche (CRA), a c. 0.75 km 3 single-event, long-runout, catastrophic failure interpreted to have been coseismically triggered by a large to great earthquake c. 660 AD on the Alpine Fault. Despite its size and remarkable preservation, the CRA deposit has been previously identified as a terminal moraine and fault-damaged outcrop, highlighting the common misinterpretation of similar rock avalanche deposits. Comparisons are drawn between the CRA and other Alpine Fault-attributed rock avalanches, such as the better-studied c. 860 AD Round Top rock avalanche, to re-assess coseismic rock avalanche hazard. Structural relationships indicate the rock mass comprising the CRA may have formerly been a portion of a larger (c. 3 km 3 ) RSF, before its catastrophic collapse on a deep-seated gravitational collapse structure (sackung). Sackungen and RSFs are common throughout the Southern Alps and other mountainous regions worldwide; in many cases, they should be considered potential precursors to catastrophic failure events. Two masses of rock in the Cascade River Valley show precursory signs of potential catastrophic failures of up to c. 2 km 3 ; a similar mass may threaten the town of Franz Josef.

Description: This study analyzes the mechanism of the landslide event at Hsiaolin Village during Typhoon Morakot in 2009. This landslide event resulted in 400 deaths. The extremely high intensity and accumulative rainfall events may cause large-scale and complex landslide disasters. To study and understand a landslide event, a combination of field investigations and numerical models is used. The landslide area is determined by comparing topographic information from before and after the event. Physiographic parameters are determined from field investigations. These parameters are applied to a numerical model to simulate the landslide process. Due to the high intensity of the rainfall event, 1,675 mm during the 80 h before the landslide event, the water content of soil was rapidly increased causing a landslide to occur. According to the survivors, the total duration of the landslide run out was less than 3 min. Simulation results indicated that the total duration was about 150 s. After the landslide occurrence, the landslide mass separated into two parts by a spur at EL 590 in about 30 to 50 s. One part passed the spur in about 30 to 60 s. One part inundated the Hsiaolin Village and the other deposited at a local river channel and formed a landslide dam. The landslide dam had height between 50 and 60 m and length between 800 and 900 m. The simulation result shows that the proposed model can be used to evaluate the potential areas of landslides induced by extremely high intensity rainfall events.

Description: The prediction of active landslide displacement is a critical component of an early warning system and helps prevent property damage and loss of human lives. For the colluvial landslides in the Three Gorges Reservoir, the monitored displacement, precipitation, and reservoir level indicated that the characteristics of the deformations were closely related to the seasonal fluctuation of rainfall and reservoir level and that the displacement curve versus time showed a stepwise pattern. Besides the geological conditions, landslide displacement also depended on the variation in the influencing factors. Two typical colluvial landslides, the Baishuihe landslide and the Bazimen landslide, were selected for case studies. To analyze the different response components of the total displacement, the accumulated displacement was divided into a trend and a periodic component using a time series model. For the prediction of the periodic displacement, a back-propagation neural network model was adopted with selected factors including (1) the accumulated precipitation during the last 1-month period, (2) the accumulated precipitation over a 2-month period, (3) change of reservoir level during the last 1 month, (4) the average elevation of the reservoir level in the current month, and (5) the accumulated displacement increment during 1 year. The prediction of the displacement showed a periodic response in the displacement as a function of the variation of the influencing factors. The prediction model provided a good representation of the measured slide displacement behavior at the Baishuihe and the Bazimen sites, which can be adopted for displacement prediction and early warning of colluvial landslides in the Three Gorges Reservoir.

Description: Calabria is one of the Italian regions mostly affected by mass movements. The case study of a densely populated neighborhood (Ianò) located in the central-western sector of Calabria is presented. The several landslides triggered in February 2010 caused heavy damages to the built area, infrastructures and productions of this neighborhood, and increased the risk for the inhabitants. The results obtained through field surveys, photo interpretation, analyses of rainfall data and of the urban fabric evolution, historical survey on the reports of the damages caused by landslides, have enabled to formulate hypotheses on the potential causes that triggered landslide events and produced severe consequences on the area. These results have revealed that almost all landslides of February 2010 are partial reactivations of pre-existing landslide deposits. Moreover, the analyses have indicated a critical role of cumulative rainfalls over an interval of 15 days. However, the severe damage framework is explained through an unplanned urbanization which took place across the years on an area characterized by a high level of instability per se. Some buildings have been erected in proximity of or within pre-existing landslide scarps; in other cases, buildings have been constructed even inside the landslide bodies.

Description: 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.

Description: The fluctuation of the water level in a reservoir may induce various types of slope movements. Some of these movements are new, whereas others are old but reactivated. Many ancient landslide accumulations are distributed in the deep valleys of the eastern Qinghai–Tibet Plateau margin in China and will likely be reactivated after the completion of reservoirs and pose a risk to reservoirs, dams, facilities, and towns near mountainous areas. The Shuangjiaping ancient landslide, located in the Dadu River, Sichuan Province, China, is an example of this case. Since August 2010, the western part of the accumulation body has seen the gradual appearance of deformations. The Pubugou reservoir water level rises and inundates the front edge of the accumulation body, thus threatening the safety of the national highway G108 and 37 houses on it. This study is based on field work investigation, drilling work, aerial photography, and profile survey. The site-scale investigation shows that the deformation area is only a part of an ancient landslide accumulation, with an area of approximately 50.4 × 10 4  m 2 and a volume of ca. 956 × 10 4  m 3 . Boundary and deposit characteristics of landslide accumulation are specified, which could be divided into four zones, namely, zones A and C, which are an avalanche accumulation area mainly composed of large blocks with diameter ranging from 1 to 3 m (some blocks have a diameter ranging from 5 to 10 m), zone B, a residual integrated rock mass accumulation area with “fake bedrock,” and zone D, a fine material accumulation area. A conceptual model is proposed to explain the mechanism and sliding process of this ancient landslide. The model includes translational sliding, stopping and hanging in air, avalanche accumulating, and transforming. The saltation of topography, material structure, and kinematic characteristics is the evidence used to identify the ancient landslide in deeply incised mountain areas. The current activity is found to be a surficial deposit displacement, and the whole landslide accumulation is stable or quasi-stable.

Description: The initiation of debris flows is commonly attributed either to fluidization as a result of rainfall-induced landslides or to gully erosion induced by concentrated runoffs. A series of flume tests have been performed to show how the initial soil moisture influences the initiation of debris flows. At the start of each experiment, surface runoff was generated over loose granular deposits, triggering debris flows. These experimental debris flows enacted different scenarios according to the small variations among the initial soil moistures. In the loose granular deposits with initial soil moistures ranging from 1 to 5 %, most runoff water could infiltrate and trigger a landslide, which accelerated within 1 s to speed over 1 ms −1 and then transformed into a debris flow. In the same soil deposits with initial moistures 〉5 or 〈1 %, the debris flow was initiated by slow gully erosion with episodic events of damming and breaching due to small-scale landslides occurring on the side-slopes of the erosion valley. The slope failures were not triggered by positive pore pressure but by a decrease in suction due to the wetting of the soil. This suction decrease in initially unsaturated slopes explains why the transformation of these slope failures into debris flows are due not only to an increase of pore pressure leading to soil liquefaction, which is one of the expected triggering mechanisms, but also to a loss of the cohesive strength of the soil.

Description: This paper presents a methodology for constructing fragility functions to characterise slope stability under a range of catastrophic earthquakes and rainfalls. The procedures for creating fragility functions, including the first-order reliability method (FORM) and the copula-based sampling method (CBSM), are demonstrated using a selection of typical slopes. The most common failure modes are included, such as the shallow sliding of an infinite slope, circular slip surface of a homogeneous slope, and tetrahedral wedge failure in a rock slope. Owing to the proposed approach, the fragility function can be applied to quantify the failure probabilities over a range of loading conditions with ease, as these are attributed to a function, rather than a design point. The advantage of these definitions is that the uncertainties of correlated soil shear strengths can be incorporated into the reliability models. The established procedure can provide a basis for describing vulnerable behaviour of a slope under various loading conditions and geometries.

Description: Early warning systems (EWSs) rely on the capacity to forecast a dangerous event with a certain amount of advance by defining warning criteria on which the safety of the population will depend. Monitoring of landslides is facilitated by new technologies, decreasing prices and easier data processing. At the same time, predicting the onset of a rapid failure or the sudden transition from slow to rapid failure and subsequent collapse, and its consequences is challenging for scientists that must deal with uncertainties and have limited tools to do so. Furthermore, EWS and warning criteria are becoming more and more a subject of concern between technical experts, researchers, stakeholders and decision makers responsible for the activation, enforcement and approval of civil protection actions. EWSs imply also a sharing of responsibilities which is often averted by technical staff, managers of technical offices and governing institutions. We organized the First International Workshop on Warning Criteria for Active Slides (IWWCAS) to promote sharing and networking among members from specialized institutions and relevant experts of EWS. In this paper, we summarize the event to stimulate discussion and collaboration between organizations dealing with the complex task of managing hazard and risk related to active slides.

Description:    We present a new approach for mapping open cracks and tension fractures within rock slope instabilities and rock cliffs, which resides in high-resolution ground-based and airborne infrared thermography (IRT). The method is restricted to cold seasons, and its utility is demonstrated through three examples from the Flysch Belt of the Outer West Carpathians (rockslides at Kopce Hill and Mt. Kněhyně) and from the Northern Calcareous Alps (deep-seated gravitational slope deformations in Gschliefgraben/Mt. Traunstein). The approach is based on a contrast between temperatures deep within the rock mass, which at a depth of few meters represent local mean annual values, and winter-time temperatures of the ground surface. In winter, warmer, buoyant air from depth rises to the ground surface through open cracks and joints, and the temperature contrast can be detected by IRT. Our test survey was conducted in the beginning of February 2012, in order to achieve the best contrast between temperatures around open tension cracks and the adjacent ground. For temperature sensing, we used a FLIR B360 thermal camera; for airborne surveys in the ambient air, temperatures at the time of our surveys ranged from approximately −19 to −7 °C. IRT results conclusively revealed the presence of open cracks, loosened rock zones, and pseudo-karst caves over a distance sometimes greater than 1 km. The IRT approach proved useful for rapidly assessing the distribution of open cracks and tension fractures, key information required for assessing rockfall and rockslide hazard. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s10346-012-0367-z Authors Ivo Baroň, Geological Survey of Austria, Neulinggasse 38, 1030 Vienna, Austria David Bečkovský, Centre AdMaS, Faculty of Civil Engineering, Technical University Brno, Veveří 95, 602 00 Brno, Czech Republic Lumír Míča, Centre AdMaS, Faculty of Civil Engineering, Technical University Brno, Veveří 95, 602 00 Brno, Czech Republic Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    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. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s10346-012-0366-0 Authors L. Cascini, University of Salerno, Salerno, Italy S. Cuomo, University of Salerno, Salerno, Italy M. Pastor, Universidad Politecnica de Madrid, Madrid, Spain Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Landslides are widespread along the north-western coast of the Island of Malta and are strictly linked to the structural setting. Exemplary cases of rock spreading and block sliding phenomena characterise this stretch of coast. They are favoured by the overposition of two different geological units widely outcropping there, the Blue Clay Formation and the Upper Coralline Limestone Formation. The latter forms a wide plateau, bordered by vertical cliffs. At the foot of the cliffs, clayey terrains crop out and develop gentle slopes covered by large blocks detached and moved by rock spreading and block sliding phenomena. These mass movements are favoured by the fragile behaviour of limestones, which cap clays, otherwise characterised by visco-plastic properties. In order to investigate the kinematics and the evolution of these types of coastal landslides, a multidisciplinary and multitechnical approach was applied on a study site, named Il-Prajjet, which provides a spectacular case of rock spreading evolving into block sliding. This paper illustrates the results achieved by means of different engineering geological and geophysical techniques allied with traditional detailed geomorphological survey and mapping. In particular, the surface displacements of the landslides were determined using long-term GPS observations, acquired approximately every 6 months, over a 4.5-year period. A network of GPS benchmarks were distributed on the edge of a limestone plateau affected by rock spreading and on a series of displaced blocks making up a large block slide, finally enabling the definition of the state of activity and the rates of movement to be performed. In addition, the results deriving from two continuous fissurimeters more recently installed at the edge of two persistent joints over the block sliding area are outlined, with reference to the correlation between variations of crack apertures and precipitation input. In order to identify main structural discontinuities and to reconstruct variability of underground surface contact between clays and overlying limestones, Resistivity Tomography profiles and GPR investigations were carried out. Finally, the results obtained by combining the outputs of geophysical surveys and different field monitoring activities can be considered a first step on which numerical models can be developed and validated, in order to assess landslide hazard and risk of this stretch of Maltese coastline. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s10346-012-0347-3 Authors Matteo Mantovani, Research Institute for Geo-hydrological Protection, CNR-IRPI. National Research Council of Italy, Corso Stati Uniti 4, 35127 Padua, Italy Stefano Devoto, Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Largo S. Eufemia 19, 41121 Modena, Italy Emanuele Forte, Department of Mathematics and Geosciences, University of Trieste, Via E. Weiss 1, 34128 Trieste, Italy Arianna Mocnik, Department of Mathematics and Geosciences, University of Trieste, Via E. Weiss 1, 34128 Trieste, Italy Alessandro Pasuto, Research Institute for Geo-hydrological Protection, CNR-IRPI. National Research Council of Italy, Corso Stati Uniti 4, 35127 Padua, Italy Daniela Piacentini, Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Largo S. Eufemia 19, 41121 Modena, Italy Mauro Soldati, Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Largo S. Eufemia 19, 41121 Modena, Italy Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    GIS-based landslide susceptibility maps for the Kankai watershed in east Nepal are developed using the frequency ratio method and the multiple linear regression technique. The maps are derived from comparing observed landslides with possible causative factors: slope angle, slope aspect, slope curvature, relative relief, distance from drainage, land use, geology, distance from faults and mean annual rainfall. The consistency of the maps is evaluated using landslide density analysis, success rate analysis and spatially agreed area approach. The first two analyses produce almost identical quantitative results, whereas the last approach is able to reveal spatial differences between the maps and also to improve predictions in the agreed high landslide-susceptible area. Content Type Journal Article Category Original Paper Pages 1-15 DOI 10.1007/s10346-012-0361-5 Authors Prabin Kayastha, Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, 1050 Brussels, Belgium Megh Raj Dhital, Mountain Risk Engineering Unit, Tribhuvan University, Kirtipur, Kathmandu, Nepal Florimond De Smedt, Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, 1050 Brussels, Belgium Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Landslides are one of the most dangerous hazards in Vietnam. Most landslides occur at excavated slopes, and natural slope failures are rare in the country. However, the volume of natural slope failures can be very significant and can badly affect large areas. After a long period of heavy rainfall in the fourth quarter of 2005 in Van Canh district, a series of landslides with volumes of 20,000–195,000 m 3 occurred on 15 December 2005. The travel distances for the landslides reached over 300–400 m, and the landslides caused some remarkable loud booming noises. The failures took place on natural slopes with unfavorable geological settings and slope angles of 28–31°. The rainfall in the fourth quarter of 2005 is estimated to have a return period of 100 years and was the main triggering factor. Because of the large affected area and low population density, resettling people from the dangerous landslide-prone residential areas to safer sites was the most appropriate solution. In order to do so, a map of landslide susceptibility was produced that took into account slope angle, distance to faults, and slope aspect. The map includes four levels from low to very high susceptibility to landslides. Content Type Journal Article Category Recent Landslides Pages 1-12 DOI 10.1007/s10346-012-0362-4 Authors Do Minh Duc, Department of Geotechnics, Faculty of Geology, VNU University of Science, 334 Nguyen Trai,, Thanh Xuan,, Hanoi, Vietnam Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    In recent years, climate change and retreating glaciers constitute a major hazard in the Himalaya of South Asia. Glacial lakes are rapidly developing or increasing due to climate change. The rapid development of the lake may cause outburst of the lake. The outburst discharge from the glacial lake can cause catastrophic flooding and disaster in downstream area. Therefore, it is necessary to investigate the impact of climate change on glacial lakes and to understand the characteristics of the glacial lake outburst. In this study, the field assessment of Tsho Rolpa Glacial Lake in the Himalaya of Nepal has been presented and the impact of climate change on this glacial lake has been discussed. The Tsho Rolpa Glacial Lake is the largest and most potentially dangerous glacial lake in Nepal. In addition, a numerical model has been also developed for computing the characteristics of glacial lake outburst due to moraine dam failure by seepage and water overtopping. The numerical model is tested for the flume experimental cases. The simulated results of the outburst discharge, the dam surface erosion, and the temporal variation of the moisture movement in the dam are compared with those obtained from the hydraulic model experiments. The moisture profile calculated by numerical model was agreeable with the experimental moisture profile. The simulated failure surface of the dam due to seepage by considering the suction in slope stability analysis gave more agreeable results than the Janbu's simplified method. The results of the outburst discharge and dam surface erosion also agreed with the experimental results. Content Type Journal Article Category Original Paper Pages 1-15 DOI 10.1007/s10346-012-0327-7 Authors Badri Bhakta Shrestha, International Centre for Water Hazard and Risk Management (ICHARM), Public Works Research Institute (PWRI), Tsukuba, Japan Hajime Nakagawa, Disaster Prevention Research Institute (DPRI), Kyoto University, Kyoto, Japan Kenji Kawaike, Disaster Prevention Research Institute (DPRI), Kyoto University, Kyoto, Japan Yasuyuki Baba, Disaster Prevention Research Institute (DPRI), Kyoto University, Kyoto, Japan Hao Zhang, Disaster Prevention Research Institute (DPRI), Kyoto University, Kyoto, Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    In the framework of the European Soil Thematic Strategy and the associated proposal of a Framework Directive on the protection and sustainable use of soil, landslides were recognised as a soil threat requiring specific strategies for priority area identification, spatial hazard assessment and management. This contribution outlines the general specifications for nested, Tier-based geographical landslide zonings at small spatial scales to identify priority areas susceptible to landslides (Tier 1) and to perform quantitative susceptibility evaluations within these (Tier 2). A heuristic, synoptic-scale Tier 1 assessment exploiting a reduced set of geoenvironmental factors derived from common pan-European data sources is proposed for the European Union and adjacent countries. Evaluation of the susceptibility estimate with national-level landslide inventory data suggests that a zonation of Europe according to, e.g. morphology and climate, and performing separate susceptibility assessments per zone could give more reliable results. To improve the Tier 1 assessment, a geomorphological terrain zoning and landslide typology differentiation are then applied for France. A multivariate landslide susceptibility assessment using additional information on landslide conditioning and triggering factors, together with a historical catalogue of landslides, is proposed for Tier 2 analysis. An approach is tested for priority areas in Italy using small administrative mapping units, allowing for relating socioeconomic census data with landslide susceptibility, which is mandatory for decision making regarding the adoption of landslide prevention and mitigation measures. The paper concludes with recommendations on further work to harmonise European landslide susceptibility assessments in the context of the European Soil Thematic Strategy. Content Type Journal Article Category Original Paper Pages 1-18 DOI 10.1007/s10346-012-0349-1 Authors Andreas Günther, Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655 Hannover, Germany Paola Reichenbach, Consiglio Nazionale delle Ricerche, Istituto di Ricerca per la Protezione Idrogeologica, Perugia, Italy Jean-Philippe Malet, Institut de Physique du Globe de Strasbourg (CNRS UMR 7516), Université de Strasbourg/EOST, Strasbourg, France Miet Van Den Eeckhaut, Institute for Environment and Sustainability, Joint Research Centre, European Commission, Ispra, Varese, Italy Javier Hervás, Institute for Environment and Sustainability, Joint Research Centre, European Commission, Ispra, Varese, Italy Claire Dashwood, British Geological Survey, Nottingham, UK Fausto Guzzetti, Consiglio Nazionale delle Ricerche, Istituto di Ricerca per la Protezione Idrogeologica, Perugia, Italy Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The Faroe Islands in the North Atlantic Ocean are susceptible to flow-type landslides in coarse-grained highly organic colluvium. Following several hazardous debris avalanche events, research work has been initiated to quantify landslide risk. A central task in this work is to predict landslide runout behavior. From numerical simulation of four debris avalanches, this study provides a first screening of which rheology and appertaining input parameters best predict runout behavior of debris avalanches in the Faroe Islands. Three rheologies (frictional, Voellmy, and Bingham) are selected and used for individual back analysis of the events in the numerical models BING and DAN3D. A best fit rheology is selected from comparing predicted and observed landslide runout behavior. General back analysis to identify the optimal input parameters for the chosen rheology is performed by cross validation, where each debris avalanche is modeled with input parameters from the three other events. Optimal input parameters are found from the model run producing the most accurate runout length and velocity. The Bingham is selected as the best fit rheology, a result differing from similar studies of coarse-grained landslides. A reason for why particularly the frictional rheology proves unsuitable is its tendency to produce too long runout lengths of the low-weight runout material, a result showing important limitations for using the frictional rheology in DAN3D. Optimal Bingham input parameters are τ y  = 980 Pa and μ b  = 117 Pa/s. However, future studies performed in 2D models are needed for precise parameterization before results can be used for landslide risk assessment. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s10346-012-0355-3 Authors Mads-Peter J Dahl, Norwegian Water Resources and Energy Directorate, Middelthunsgate 29, Majorstua, Postbox 5091, 0301 Oslo, Norway Peter Gauer, Norwegian Geotechnical Institute, Postbox 3930,, Ullevaal Stadion, 0806 Oslo, Norway Bjørn G Kalsnes, Norwegian Geotechnical Institute, Postbox 3930,, Ullevaal Stadion, 0806 Oslo, Norway Lis E Mortensen, Jarðfeingi (Faroese Earth and Energy Directorate), Brekkutún 1, Postbox 3059, 0110 Tórshavn, Faroe Islands Niels H Jensen, Department of Environmental, Social and Spatial Change, Roskilde University, Universitetsvej 1, Postbox 260, 4000 Roskilde, Denmark Anita Veihe, Department of Environmental, Social and Spatial Change, Roskilde University, Universitetsvej 1, Postbox 260, 4000 Roskilde, Denmark Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The present paper illustrates the results of an integrated study of a large landslide located on the southern slope of Mount la Civita (Molise, Southern Apennine), an E–W elongated, SSE dipping and 890-m-high monocline carbonate ridge. The upper part of the slope affected by the landslide is largely controlled by strata attitude while its basal part is marked by a strike–slip fault causing the tectonic juxtaposition of the carbonate successions against predominantly clayey flysch units. An integrated study, including geological, geomorphological and geotechnical investigations, was carried out to determine the features of the landslide and to plan further investigation and monitoring. In particular, from 2002 to 2004, Differential Global Positioning System monitoring and core drillings, coupled with inclinometer measurements, were carried out to determine the landslide’s kinematics, extent, depth to the surface of rupture and rates of movement. Inclinometer data revealed the presence of the rupture surface at a depth of about 20 m. DGPS monitoring allowed rates of movement up to several tens of centimetres per year to be recorded. The nearby village of Civitanova del Sannio can still be considered at risk due to the landslide, as recent remedial works, consisting mainly of very shallow re-shaping of the slope by blasting and partial filling of trenches, did not succeed in stopping its movement. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s10346-012-0351-7 Authors Pietro P. C. Aucelli, Department of Sciences for the Environment, University of Naples Parthenope, Centro Direzionale C/4, 80143 Naples, Italy Emilio Casciello, Institute of Earth Sciences “Jaume Almera”, Consejo Superior de Investigaciones Cientificas - CSIC, Barcelona, Spain Massimo Cesarano, Department of Biosciences and Territory, University of Molise, C.da Fonte Lappone, 86090 Pesche (IS), Italy Sebastiano Perriello Zampelli, Department of Architectural and Environmental Design, University of Naples Federico II, via Forno Vecchio 36, 80134 Naples, Italy Carmen M. Rosskopf, Department of Biosciences and Territory, University of Molise, C.da Fonte Lappone, 86090 Pesche (IS), Italy Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The Aresawa rockslide in the Japanese Alps encountered a deep, partial collapse during an early snow-melting period in May 2004, followed by further progressive movement of the headscarp area. This paper reconstructs the pre-failure topography of the Aresawa rockslide based on the analysis of aerial photographs taken in multiple periods, and analyzes the factors controlling the threshold for the 2004 collapse. At least seven months before the collapse, new tension cracks emerged about 25 m behind the headscarp as a result of downslope movement of an unstable rock slab 5–10 × 10 5  m 3 in volume, accompanied by the development of a slip plane below a pre-existing shallow trough (sackung feature). The collapse finally occurred when progressive weakening of the rock mass was combined with water infiltration into the ground during rapid snow melting. Content Type Journal Article Category Recent Landslides Pages 1-8 DOI 10.1007/s10346-012-0353-5 Authors Ryoko Nishii, Faculty of Life and Environmental Sciences (Ikawa University Forest), University of Tsukuba, Shizuoka, Japan Norikazu Matsuoka, University of Tsukuba, Ibaraki, Japan Hiromu Daimaru, Forestry and Forest Products Research Institute, Ibaraki, Japan Masatsugu Yasuda, Chiba University, Chiba, Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The UK is a country with limited direct experience of natural disasters. Whilst landslide losses are not negligible and fatalities are rare, accounts are under-reported. Financial losses from landslides are poorly understood but likely to be considerably in excess of £10 million per year. As a result, a strategic management framework has evolved based upon small, low-impact events punctuated by occasional larger events or larger landslides affecting urban areas. We present an overview of the different landslide management mechanisms in the UK and discuss them in context of cases studies to explore their effectiveness. We conclude with three issues that may have implications for landslide management in the UK and other ‘ low-risk ’ countries. Firstly, the evidence base by which landslide hazards and risks are measured is insufficient and limitations in existing information need to be better understood. Secondly, existing guidance on strategic and responsive management needs to be assessed for its fitness for purpose. Thirdly, we encourage debate about the importance of near misses . Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s10346-012-0346-4 Authors A. D. Gibson, School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth, UK M. G. Culshaw, School of Civil Engineering, University of Birmingham, Birmingham, UK C. Dashwood, British Geological Survey, Nottingham, UK C. V. L. Pennington, British Geological Survey, Nottingham, UK Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Landslide dams in mountainous areas are quite common. Typically, intense rainfalls can induce upstream flows along the sloping channel, which greatly affects the stability and failure modes of landslide dams. If a series of landslide dams are sequentially collapsed by an incoming mountain torrent (induced by intense rainfall), large debris flows can be formed in a short period of time. This also amplifies the magnitude of the debris flows along the flow direction. The catastrophic debris flows, which occurred in Zhouqu, China on August 8, 2010, were indeed caused by intense rainfall and the upstream cascading failure of landslide dams along the gullies. Experimental tests were conducted in a sloping channel to understand the dynamic process of cascading landslide dam failures and their effect on flow scale amplification. Similar to the Zhouqu conditions, the modeled landslide dams were distributed along a sloping channel and breached by different upstream flows. For each experiment, the front flows were sampled, the entrained grain sizes were analyzed, and the front discharge along the channel was measured. The results of these experiments show that landslide dams occurring along the channel can be destroyed by both high and low discharge flows, although the mechanisms are quite different for the two flow types. Regardless of flow type, the magnitude of the flows significantly increases after a cascading failure of landslide dams, resulting in an increase in both the diameter and the entrained coarse particles percentage. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s10346-012-0352-6 Authors Gordon G. D. Zhou, Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu, China P. Cui, Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu, China H. Y. Chen, Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu, China X. H. Zhu, Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu, China J. B. Tang, Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu, China Q. C. Sun, State Key Laboratory for Hydroscience and Engineering, Tsinghua University, Beijing, China Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Rainfall-induced debris flows involving ash-fall pyroclastic deposits that cover steep mountain slopes surrounding the Somma-Vesuvius volcano are natural events and a source of risk for urban settlements located at footslopes in the area. This paper describes experimental methods and modelling results of shallow landslides that occurred on 5–6 May 1998 in selected areas of the Sarno Mountain Range. Stratigraphical surveys carried out in initiation areas show that ash-fall pyroclastic deposits are discontinuously distributed along slopes, with total thicknesses that vary from a maximum value on slopes inclined less than 30° to near zero thickness on slopes inclined greater than 50°. This distribution of cover thickness influences the stratigraphical setting and leads to downward thinning and the pinching out of pyroclastic horizons. Three engineering geological settings were identified, in which most of the initial landslides that triggered debris flows occurred in May 1998 can be classified as (1) knickpoints, characterised by a downward progressive thinning of the pyroclastic mantle; (2) rocky scarps that abruptly interrupt the pyroclastic mantle; and (3) road cuts in the pyroclastic mantle that occur in a critical range of slope angle. Detailed topographic and stratigraphical surveys coupled with field and laboratory tests were conducted to define geometric, hydraulic and mechanical features of pyroclastic soil horizons in the source areas and to carry out hydrological numerical modelling of hillslopes under different rainfall conditions. The slope stability for three representative cases was calculated considering the real sliding surface of the initial landslides and the pore pressures during the infiltration process. The hydrological modelling of hillslopes demonstrated localised increase of pore pressure, up to saturation, where pyroclastic horizons with higher hydraulic conductivity pinch out and the thickness of pyroclastic mantle reduces or is interrupted. These results lead to the identification of a comprehensive hydrogeomorphological model of susceptibility to initial landslides that links morphological, stratigraphical and hydrological conditions. The calculation of intensities and durations of rainfall necessary for slope instability allowed the identification of deterministic hydrological thresholds that account for uncertainty in properties and observed rainfall intensities. Content Type Journal Article Category Original Paper Pages 1-16 DOI 10.1007/s10346-012-0348-2 Authors P. De Vita, University of Naples “Federico II”, Naples, Italy E. Napolitano, University of Naples “Federico II”, Naples, Italy J. W. Godt, U.S. Geological Survey, Denver, CO 80225, USA R. L. Baum, U.S. Geological Survey, Denver, CO 80225, USA Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    This is the first landslide inventory map in the island of Lefkada integrating satellite imagery and reports from field surveys. In particular, satellite imagery acquired before and after the 2003 earthquake were collected and interpreted with the results of the field survey that took place 1 week after this strong (Mw = 6.3) event. The developed inventory map indicates that the density of landslides decreases from west to east. Furthermore, the spatial distribution of landslides was statistically analyzed in relation to the geology and topography for investigating their influence to landsliding. This was accomplished by overlaying these causal factors as thematic layers with landslide distribution data. Afterwards, weight values of each factor were calculated using the landslide index method and a landslide susceptibility map was developed. The susceptibility map indicates that the highest susceptibility class accounts for 38 % of the total landslide activity, while the three highest classes that cover the 10 % of the surface area, accounting for almost the 85 % of the active landslides. Our model was validated by applying the approaches of success and prediction rate to the dataset of landslides that was previously divided into two groups based on temporal criteria, estimation and validation group. The outcome of the validation dataset was that the highest susceptibility class concentrates 18 % of the total landslide activity. However, taking into account the frequency of landslides within the three highest susceptibility classes, more than 85 %, the model is characterized as reliable for a regional assessment of earthquake-induced landslides hazard. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s10346-012-0357-1 Authors George Papathanassiou, Department of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece Sotiris Valkaniotis, Department of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece Athanassios Ganas, Institute of Geodynamics, National Observatory of Athens, Athens, Greece Spyros Pavlides, Department of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The objective of this paper is to develop an efficient analytical method for assessing the vulnerability of low-rise reinforced concrete buildings subjected to seismically induced slow-moving earth slides. Vulnerability is defined in terms of probabilistic fragility curves, which describe the probability of exceeding a certain limit state of the building, on a given slope, versus the Peak Horizontal Ground Acceleration (PHGA) at the assumed “seismic bedrock”, allowing for the quantification of various sources of uncertainty. The proposed method is based on a two-step, uncoupled approach. In the first step, the differential permanent landslide displacements at the building’s foundation level are estimated using a dynamic non-linear finite difference slope model. In the second step, the calculated differential permanent displacements are statically imposed at the foundation level to assess the building’s response to differing permanent seismic ground displacements using a finite element code. Structural limit states are defined in terms of threshold values of strains for the reinforced concrete structural components. The method is applied to typical low-rise reinforced concrete frame buildings on shallow foundations with varying strength and stiffness characteristics (isolated footings and continuous slab foundation), standing near the crest of a relatively slow-moving earth slide. Two different slope models are selected representing a cohesive and a purely frictional soil material. The paper describes the method and the derived fragility curves for the selected building and slope typologies that could be used in quantitative risk assessment studies at site-specific and local scales. Content Type Journal Article Category Original Paper Pages 1-20 DOI 10.1007/s10346-012-0345-5 Authors S D Fotopoulou, Department of Civil Engineering, Laboratory of Soil Mechanics, Foundations and Geotechnical Earthquake Engineering, Aristotle University, Thessaloniki, Greece K D Pitilakis, Department of Civil Engineering, Laboratory of Soil Mechanics, Foundations and Geotechnical Earthquake Engineering, Aristotle University, Thessaloniki, Greece Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    An earthflow near Cenes de la Vega (southern Spain) was first observed after a heavy rain in January 2010 in an area where a spring had existed. Initially, the landslide affected only the lower part of the slope. Displaced materials accumulated over terraces and the river course, damming it. A year later, a new rainy period reactivated (or increased the activity of) the instability. It progressed in two ways: by sliding and involving progressively higher parts of the slope with the head scarp approaching the top of the slope, and by widening in the central part of the body. Near the top of the slope, there is a pipeline that supplies water to the city of Granada. The most probable triggering factor of the landslide seems to be a combination of persistent water leakage from the pipe, which has saturated the materials, and intense rainfall. Content Type Journal Article Category Recent Landslides Pages 1-7 DOI 10.1007/s10346-012-0358-0 Authors Jesús Garrido, Departamento de Ingeniería Civil, Universidad de Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain José Delgado, Departamento de Ciencias de la Tierra, Universidad de Alicante, P.O. Box 99, Alicante, 03080 Spain Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The goals of this work are to show the range of debris-flow volumes and watershed characteristics for several locations, and the differences in flow volumes for events triggered soon after wildfire. A dataset of 929 events was divided into groups based on location and burn status. The three unburned locations show significant differences: debris flows from the Italian Alps are larger and generate more debris per unit basin area or unit channel length than flows in the Western USA or in the Pacific Northwest. However, some of the observed differences may be attributed to the skew of the Italian Alps dataset towards larger events, and the small size and limited range of the Pacific Northwest data. For burned watersheds in the Western U.S. events, there is a clear progression in decreasing volume in debris flows as basins recover from the wildfire: it takes approximately 1 year, or at a few locations, as much as 3 years, for debris production to return to pre-fire rates. The difference is most apparent when the data are normalized for basin area (the area yield, which is 2× larger for burned basins) or for channel length (the length yield, which is 1.6× larger for burned basins). When normalized simultaneously for basin area, channel length, and channel gradient, burned areas produce significantly more debris (2.7–5.4 times as much). Burned areas in the Western USA are more sensitive to wildfire and produce larger debris flows than burned areas in more humid climates such as the Pacific Northwest. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s10346-012-0354-4 Authors Paul M. Santi, Department of Geology and Geological Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA Luca Morandi, Department of Geology and Geological Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The northern Nagano Prefecture earthquake, M JMA  6.7 (Mw 6.2), which is inferred to have been triggered by the huge (Mw 9.0) March 11, 2011 Tohoku earthquake, occurred on March 12, 2011, in northern Nagano Prefecture, an area in Japan famous for heavy snowfall. A large number of landslides were triggered by the 12 March earthquake, and it caused building damage in the area of the epicenter. To clarify characteristics of the distribution and dynamic behavior of these landslides, we analyzed aerial photographs and conducted field surveys in and around the epicentral area. Large-scale landslides with long distance run-outs are a remarkable characteristic of the landslides induced by this earthquake. The long travel distance is considered to be related to the thick snowpack at the time the earthquake occurred. Moderate scale deep-seated landslides and shallow landslides were also observed in the study area. Based on an analysis of landslides with the active fault on which the earthquake is believed to have occurred, most of these landslides were distributed on the hanging wall of the active fault, within a distance of 12 km from the fault. Content Type Journal Article Category Recent Landslides Pages 1-8 DOI 10.1007/s10346-012-0344-6 Authors Baator Has, Asia Air Survey, Co., Ltd, Kawasaki, Japan Tomoyuki Noro, Snow Avalanche and Landslide Research Center, PWRI, Myoko, Japan Kiyoteru Maruyama, Snow Avalanche and Landslide Research Center, PWRI, Myoko, Japan Akira Nakamura, Snow Avalanche and Landslide Research Center, PWRI, Myoko, Japan Kiichiro Ogawa, Asia Air Survey, Co., Ltd, Kawasaki, Japan Satoshi Onoda, Asia Air Survey, Co., Ltd, Kawasaki, Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    On 14 April 2010 at 07:49 (Beijing time), a catastrophic earthquake with Ms 7.1 struck Yushu County, Qinghai Province, China. A total of 2,036 landslides were interpreted from aerial photographs and satellite images, verified by selected field checking. These landslides cover about a total area of 1.194 km 2 . The characteristics and failure mechanisms of these landslides are presented in this paper. The spatial distribution of the landslides is evidently strongly controlled by the locations of the main co-seismic surface fault ruptures. The landslides commonly occurred close together. Most of the landslides are small; there were only 275 individual landslide (13.5 % of the total number) surface areas larger than 1,000 m 2 . The landslides are of various types. They are mainly shallow, disrupted landslides, but also include rock falls, deep-seated landslides, liquefaction-induced landslides, and compound landslides. Four types of factors are identified as contributing to failure along with the strong ground shaking: natural excavation of the toes of slopes, which mean erosion of the base of the slope, surface water infiltration into slopes, co-seismic fault slipping at landslide sites, and delayed occurrence of landslides due to snow melt or rainfall infiltration at sites where slopes were weakened by the co-seismic ground shaking. To analyze the spatial distribution of the landslides, the landslide area percentage (LAP) and landslide number density (LND) were compared with peak ground acceleration (PGA), distance from co-seismic main surface fault ruptures, elevation, slope gradient, slope aspect, and lithology. The results show landslide occurrence is strongly controlled by proximity to the main surface fault ruptures, with most landslides occurring within 2.5 km of such ruptures. There is no evident correlation between landslide occurrences and PGA. Both LAP and LND have strongly positive correlations with slope gradient, and additionally, sites at elevations between 3,800 and 4,000 m are relatively susceptible to landslide occurrence; as are slopes with northeast, east, and southeast slope aspects. Q 4 al-pl , N, and T 3 kn 1 have more concentrated landslide activity than others. This paper provides a detailed inventory map of landslides triggered by the 2010 Yushu earthquake for future seismic landslide hazard analysis and also provides a study case of characteristics, failure mechanisms, and spatial distribution of landslides triggered by slipping-fault generated earthquake on a plateau. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s10346-012-0340-x Authors Chong Xu, Key Laboratory of Active Tectonics and Volcano, Institute of Geology, Chinese Earthquake Administration, Qijiahuozi, Deshengmenwai, P.O. Box 9803, Beijing, 100029 People’s Republic of China Xiwei Xu, Key Laboratory of Active Tectonics and Volcano, Institute of Geology, Chinese Earthquake Administration, Qijiahuozi, Deshengmenwai, P.O. Box 9803, Beijing, 100029 People’s Republic of China Guihua Yu, Key Laboratory of Active Tectonics and Volcano, Institute of Geology, Chinese Earthquake Administration, Qijiahuozi, Deshengmenwai, P.O. Box 9803, Beijing, 100029 People’s Republic of China Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Today, a stimulating debate involves the scientific community about the impact of presumable future climate changes on the human life. One of the main question marks concerns their effects on hydrological hazards. Unfortunately, often such a debate is not based on reliable data. The paper proposes a methodology based on the coupling of climatic scenarios and geotechnical analyses accounting for the potential changes in climate parameters. Some analyses have been carried out to forecast the future behaviour of a slow landslide in clay. According to the adopted model, local climate effects should cause a slow decrease in the displacement rate. Content Type Journal Article Category Original Paper Pages 1-19 DOI 10.1007/s10346-012-0339-3 Authors Luca Comegna, Department of Civil Engineering, Seconda Università degli Studi di Napoli, Via Roma 29, 81031 Aversa, Italy Luciano Picarelli, Department of Civil Engineering, Seconda Università degli Studi di Napoli, Via Roma 29, 81031 Aversa, Italy Edoardo Bucchignani, Italian Aerospace Research Center, CIRA, Capua, Italy Paola Mercogliano, Italian Aerospace Research Center, CIRA, Capua, Italy Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The International Consortium on Landslides (ICL) was founded on 21 January 2002, during the United Nations Educational, Scientific and Cultural Organization–Kyoto University Joint Symposium on Landslide Risk Mitigation and Protection of Cultural and Natural Heritage, as an activity of IGCP-425. In its first decade, ICL established the first scientific full-color journal Landslides , a new International Programme on Landslides, organized and held the First World Landslide Forum in 2008 and the Second World Landslide Forum in 2011, and recognized 15 World Centres of Excellence on Landslide Risk Reduction. A 10th anniversary conference was held on 17–20 January at the facility in which ICL’s founding meeting had been held. This conference was jointly organized by ICL and ICL-supporting organizations. During the conference, the ICL Strategic Plan 2012–2021: to create a safer geo-environment — was developed and adopted. This strategic plan accompanies this preface. Content Type Journal Article Category Preface Pages 1-10 DOI 10.1007/s10346-012-0334-8 Authors Kyoji Sassa, ICL, UNITWIN Headquarters Building, Kyoto University Uji-Campus, Uji, Kyoto 611-0011, Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    On October 12th, 2007 about 40,000 m 3 of dolomitic rock detached from the northern wall of the peak known as “Cima Una” (Val Fiscalina, Sesto Dolomites, Bolzano, Italy), and fell 900 m to Fiscalina Valley below. The event generated a dense dust cloud, which traveled up to 4 km from the source area. The failure surface was formed by two near-vertical surfaces, almost perpendicular to each other. The orientation of these surfaces is consistent with two of the main regional tectonic sets. Only a small portion of the fallen material appeared to be preserved as blocks deposited at the base of the rock wall. About a fifth of the fallen mass was deposited on a colluvial cone. The missing mass, estimated to be about 80 %, may be represented by highly fragmented rock in part deposited as sand on the valley floor and in part dispersed as a dense dust cloud generated during the rockfall. There appears to be a deficit of deposited material, which could lead underestimation in the calculation of rock–cliff recession rates. The dynamics of the rockfall, strongly conditioned by the local topography, partially explains the intense rock breakage and the generation of the dust cloud. The rockfall was not caused by an external trigger, such as an earthquake or heavy rainfall; the failure was most likely progressive due to mechanical and physical degradation along highly stressed failure surfaces, possibly promoted by permafrost degradation and freeze and thaw processes. Content Type Journal Article Category Original Paper Pages 1-16 DOI 10.1007/s10346-012-0338-4 Authors Alessia Viero, Dipartimento di Geoscienze, Università degli Studi di Padova, Padova, Italy Sandro Furlanis, Dipartimento di Scienze della Terra, Università degli Studi di Ferrara, Ferrara, Italy Cristina Squarzoni, Dipartimento di Geoscienze, Università degli Studi di Padova, Padova, Italy Giordano Teza, Dipartimento di Geoscienze, Università degli Studi di Padova, Padova, Italy Antonio Galgaro, Dipartimento di Geoscienze, Università degli Studi di Padova, Padova, Italy Piero Gianolla, Dipartimento di Scienze della Terra, Università degli Studi di Ferrara, Ferrara, Italy Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Rainfall intensity–duration (ID) thresholds are commonly used to predict the temporal occurrence of debris flows and shallow landslides. Typically, thresholds are subjectively defined as the upper limit of peak rainstorm intensities that do not produce debris flows and landslides, or as the lower limit of peak rainstorm intensities that initiate debris flows and landslides. In addition, peak rainstorm intensities are often used to define thresholds, as data regarding the precise timing of debris flows and associated rainfall intensities are usually not available, and rainfall characteristics are often estimated from distant gauging locations. Here, we attempt to improve the performance of existing threshold-based predictions of post-fire debris-flow occurrence by utilizing data on the precise timing of debris flows relative to rainfall intensity, and develop an objective method to define the threshold intensities. We objectively defined the thresholds by maximizing the number of correct predictions of debris flow occurrence while minimizing the rate of both Type I (false positive) and Type II (false negative) errors. We identified that (1) there were statistically significant differences between peak storm and triggering intensities, (2) the objectively defined threshold model presents a better balance between predictive success, false alarms and failed alarms than previous subjectively defined thresholds, (3) thresholds based on measurements of rainfall intensity over shorter duration (≤60 min) are better predictors of post-fire debris-flow initiation than longer duration thresholds, and (4) the objectively defined thresholds were exceeded prior to the recorded time of debris flow at frequencies similar to or better than subjective thresholds. Our findings highlight the need to better constrain the timing and processes of initiation of landslides and debris flows for future threshold studies. In addition, the methods used to define rainfall thresholds in this study represent a computationally simple means of deriving critical values for other studies of nonlinear phenomena characterized by thresholds. Content Type Journal Article Category Original Paper Pages 1-16 DOI 10.1007/s10346-012-0341-9 Authors Dennis M. Staley, U.S. Geological Survey, Box 25046, MS966 DFC, Denver, CO 80225, USA Jason W. Kean, U.S. Geological Survey, Box 25046, MS966 DFC, Denver, CO 80225, USA Susan H. Cannon, U.S. Geological Survey, Box 25046, MS966 DFC, Denver, CO 80225, USA Kevin M. Schmidt, U.S. Geological Survey, Menlo Park, CA, USA Jayme L. Laber, National Oceanic and Atmospheric Administration, National Weather Service, Oxnard, CA, USA Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Particularly in the last decade, landslide susceptibility and hazard maps have been used for urban planning and site selection of infrastructures. Most of the procedures for preparing of landslide susceptibility maps need high-quality landslide inventory map. Although the rainfall and seismic activities are accepted as triggering factor for landslides, designation of the triggering factor for each landslide in the inventory is almost impossible when well-documented records are unavailable. Therefore, during preparation of landslide susceptibility map, whole landslide records in the inventory map are used together without classifying based on the triggering factors. Although seismic activity is accepted as a triggering factor, possible effect of the use of seismic activity on production of landslide susceptibility map was investigated in this study, and the subject is open to discussion. For this purpose, a series of stability analyses based on circular failure and infinite slope model were performed considering different pseudostatic conditions. The results of analyses show that gentle slopes have higher susceptibility to failure than steeper ones, even if their stability conditions (susceptibilities) are similar for static condition. The seismic forces acting on failure surfaces may not be sufficiently taken into consideration in the conventionally prepared landslide susceptibility maps. Employing the general decreasing trend in stability condition based on slope face angle and the seismic acceleration, a new procedure was introduced for preparing of the landslide susceptibility map for a scenario earthquake. The prediction performance of occurring landslides increased after the procedure was applied to the conventionally prepared landslide susceptibility map. According to the threshold independent spatial performance analyses of the proposed methodology and the produced landslide susceptibility maps, the area under ROC curve values were calculated as 0.801, 0.933, and 0.947 for the maps prepared by considering conventional method and scenario earthquakes having M w values of 5.5 and 7.5, respectively. Content Type Journal Article Category Original Paper Pages 1-22 DOI 10.1007/s10346-012-0342-8 Authors H. O. Das, General Directorate of the Bank Provinces, Ankara, Turkey H. Sonmez, Department of Geological Engineering, Applied Geology Division, Hacettepe University, 06800 Ankara, Turkey C. Gokceoglu, Department of Geological Engineering, Applied Geology Division, Hacettepe University, 06800 Ankara, Turkey H. A. Nefeslioglu, Department of Geological Engineering, Faculty of Engineering, Cumhuriyet University, 58140 Sivas, Turkey Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Numerous field monitoring programs have been conducted to investigate the performance of an unsaturated soil slope subjected to rainfalls in wet seasons. Most case histories focus on the response of matric suction, which is one of the two stress-state variables governing unsaturated soil behaviour. However, effects due to another variable, net normal stress, are often ignored. Also, slope performance under alternative wet and dry seasons is rarely reported and analysed. In this study, a saprolitic hillslope situated in Hong Kong was instrumented heavily to investigate its seasonal movement due to changes of the two variables and also groundwater flow mechanism. Two-year seasonal variations of matric suction and net normal stress were monitored by tensiometers together with heat dissipation matric water potential sensors and earth pressure cells, respectively. During heavy rainstorms in wet season, there was a substantial recharge of the main groundwater table, causing a significant increase of positive pore-water pressure in deeper depths. Rupture surface likely developed at depths between 5.5 and 6 m, hence resulting in a “deep-seated” mode of downslope movement. The downslope movement resulted in a peak increase of horizontal stress. In dry seasons, matric suction of up to 190 kPa was recorded, and the associated soil shrinkage led to substantial upslope rebounds. The stress built up in wet seasons hence reduced. After monitoring period of 2 years, downslope ratcheting is identified. Up to 40 % of the downslope displacements were recovered by the upslope rebounds. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s10346-012-0343-7 Authors Anthony Kwan Leung, Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Charles Wang Wai Ng, Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Horizontal drains, used independently or as part of a more complex remediation scheme, are frequently installed to mitigate the effects of increased groundwater in slope stabilization projects. Due to a general trial and error approach to their design, the need for improved design practices has been recognized. The procedures established by Crenshaw and Santi in 2004 made some advances in this direction, but did not account for slopes with drains that were not horizontal or for sloping low-permeability layers underneath the slide mass. Furthermore, the method outlined by Crenshaw and Santi is time-consuming and requires some trial and error calculations to achieve convergence. Therefore, the method has been modified to account for nonhorizontal elements, and a horizontal drain spreadsheet has been developed to streamline the design for projects where horizontal drains will be installed. The horizontal drain spreadsheet may be used to: (1) predict a conservative piezometric profile in a drained slope for use in slope stability analyses, (2) predict piezometric heads in any single piezometer in a drainage field, and (3) predict drain spacing for design purposes. This document explains the revisions to Crenshaw and Santi’s procedures and provides instructions for applying the method. The instructions may be used for hand calculations, but are specifically intended for use with the horizontal drain spreadsheet. The spreadsheet may be used for slopes composed of silty or clayey sands, silts, and silty or sandy clays. Content Type Journal Article Category Technical Note Pages 1-10 DOI 10.1007/s10346-012-0337-5 Authors Diana I. Cook, Tetra Tech, 350 Indiana Street, Suite 500, Golden, CO 80401, USA Paul M. Santi, Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401, USA Jerry D. Higgins, Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401, USA Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The Second World Landslide Forum was held at the headquarters of Food and Agriculture Organization of the United Nations on 3–9 October 2011 in Rome, Italy. The Third World Landslide Forum (WLF3) is to be held at the China National Convention Center in Beijing, China from 2 to 6 June 2014. This article first outlines the aims and background of the World Landslide Forums, reports on the Second World Landslide Forum in Rome, and then announces the plans for the Third World Landslide Forum in Beijing. Finally, it calls for contributions for the organization of WLF3 and participation in the International Consortium on Landslides (ICL) and the International Programme on Landslides. Content Type Journal Article Category ICL/IPL Activities Pages 1-13 DOI 10.1007/s10346-012-0328-6 Authors Kyoji Sassa, International Consortium on Landslides, UNITWIN Headquarters Building, Kyoto University Uji-Campus, Uji, Kyoto, 611-0011 Japan Paolo Canuti, International Consortium on Landslides, Via La Pira 4, 50121 Florence, Italy Claudio Margottini, ISPRA-Institute for Environmental Protection & Research, Geological Survey of Italy, Vitaliano Brancati 60, 00144 Rome, Italy Yueping Yin, China Institute of Geo-Environment Monitoring, China Geological Survey, Dahuist 20#, Haidian, Beijing, China Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description: ICL-CGS Seminar on Geo-hazards in Xi’an Content Type Journal Article Category ICL/IPL Activities Pages 405-405 DOI 10.1007/s10346-011-0289-1 Authors Yueping Yin, China Geological Survey, Xicheng, Huangsidajie No.45, Beijing, 100037 China Xiaochuan Li, China Geological Survey, Xicheng, Huangsidajie No.45, Beijing, 100037 China Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X Journal Volume Volume 8 Journal Issue Volume 8, Number 3

Description:    An earthquake of M w 9.0 struck the Pacific coast in northeast Japan on March 11, 2011 and was followed by a hugely damaging tsunami along 500 km of the Japanese coastline. An inland aftershock of M. 7.0 occurred on April 11; during which, surface fault ruptures appeared on land. A large variety of landslide disasters resulted from these earthquakes in various parts of northeastern Honshu, Japan. The full extent of the landslides is still being determined. This brief report introduces some of the landslide phenomena so far investigated by the Japanese Landslide Society. These are (1) failure of a water reservoir embankment dam in Sukagawa, Fukushima prefecture, (2) landslides and surface seismic fault rupture from the April 11 aftershock in Iwaki, Fukushima, (3) a concentration of surface failures at Matsushima Bay in Miyagi prefecture, and (4) small landslides on modified slopes in residential areas around Sendai city. Content Type Journal Article Category Recent Landslides Pages 339-342 DOI 10.1007/s10346-011-0281-9 Authors Toyohiko Miyagi, Tōhoku Gakuin University, Tōhoku, Japan Daisuke Higaki, Tōhoku Gakuin University, Tōhoku, Japan Hiroshi Yagi, Tōhoku Gakuin University, Tōhoku, Japan Shoji Doshida, Tōhoku Gakuin University, Tōhoku, Japan Noriyuki Chiba, Tōhoku Gakuin University, Tōhoku, Japan Jun Umemura, Tōhoku Gakuin University, Tōhoku, Japan Go Satoh, Tōhoku Gakuin University, Tōhoku, Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X Journal Volume Volume 8 Journal Issue Volume 8, Number 3

Description: 2010 Recipient of the ICL Varnes Medal: Dr. Zaiguan Lin Content Type Journal Article Category ICL/IPL Activities Pages 403-404 DOI 10.1007/s10346-011-0288-2 Authors Kyoji Sassa, UNITWIN Headquarters Building, Professor Emeritus, Kyoto University, Uji Campus, Uji, Kyoto 611-0011, Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X Journal Volume Volume 8 Journal Issue Volume 8, Number 3

Description: Discussion to the paper “Expected damage from displacement of slow-moving slides” by M.F. Mansour, N.R. Morgenstern and C.D. Martin Content Type Journal Article Category Discussion Pages 553-555 DOI 10.1007/s10346-011-0292-6 Authors Luciano Picarelli, Department of Civil Engineering, Seconda Universita di Napoli, Aversa, Italy Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X Journal Volume Volume 8 Journal Issue Volume 8, Number 4

Description:    The international journal Landslides (ISSN 1612-510X), launched in 2004 and published by Springer Verlag, soon gained international recognition as the only specialized scientific journal in the world dedicated to different aspects of landslides, and as one of the leading world journals in the field of geological engineering. After 7 years, seven published volumes with 28 issues and 290 published papers on 2,794 pages, there is time to make a comparison with other related journals that also cover the field of landslide risk mitigation. The critical review of these seven publishing years was done using ISI Journal Citation Reports produced by Thomson Reuters, and available scientometric data from the ISI Web of Knowledge and SCOPUS. The data presented in this paper and the analysis shown may help the Editorial Board to further improve the journal into the direction of a high quality scientific journal with even higher impact on the international research community in the field of landslide risk mitigation. Content Type Journal Article Category Technical Note Pages 541-551 DOI 10.1007/s10346-011-0297-1 Authors Matjaž Mikoš, Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova cesta 2, SI-1000 Ljubljana, Slovenia Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X Journal Volume Volume 8 Journal Issue Volume 8, Number 4

Description:    The dense recordings of the K-NET and KiK-net nationwide strong motion network of 1,189 accelerometers show clearly the radiation and propagation properties of the strong ground motions associated with the 2011 off-the-Pacific Coast-of-Tohoku, Japan (Mw = 9.0) earthquake. The snapshots of seismic wave propagation reveal strong ground motions from this earthquake that originate from three large slips; the first two slips occurred over the plate interface of off-Miyagi at the southwest and the east of the hypocenter, and the third one just beneath the northern end of Ibaraki over the plate interface or in the crust. Such multiple shocks of this event caused large accelerations (maximum 1–2 G) and prolonged ground shaking lasting several minutes with dominant high-frequency ( T  〈 1 s) signals over the entire area of northern Japan. On the other hand, ground motions of relatively longer–period band ( T  = 1–2 s), which caused significant damage to wooden-frame houses, were about 1/2–1/3 of those observed near the source area of the destructive 1995 Kobe, Japan (M = 7.3) earthquake. Also, the long-period ( T  = 6–8 s) ground motion in the Kanto (Tokyo) sedimentary basin was at an almost comparable level of those observed during the recent Mw = 7 inland earthquakes, but not as large as that from the former M = 8 earthquakes. Therefore, the impact of the strong ground motion from the present M = 9 earthquake was not as large as expected from the previously M = 7–8 earthquakes and caused strong motion damage only to short-scale construction and according to instruments inside the buildings, both have a shorter ( T  〈 1 s) natural period. Content Type Journal Article Category Recent Landslides Pages 333-338 DOI 10.1007/s10346-011-0279-3 Authors Takashi Furumura, Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, Tokyo, Japan Shunsuke Takemura, The Earthquake Research Institute, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan Shinako Noguchi, Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, Tokyo, Japan Teito Takemoto, The Earthquake Research Institute, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan Takuto Maeda, Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, Tokyo, Japan Kazuhisa Iwai, Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, Tokyo, Japan Simanchal Padhy, Center for Integrated Disaster Information Research, Interfaculty Initiative in Information Studies, The University of Tokyo, Tokyo, Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X Journal Volume Volume 8 Journal Issue Volume 8, Number 3

Description:    At 4:40p.m. on November 23, 2008, the Gongjiafang slope collapsed on the north bank of Yangtze River in Wu Gorge of Three Gorges Reservoir. The 380,000-m 3 sliding mass consisted mainly of cataclastic rock. A video record of the major sliding incident was analyzed using the general laws of physical motion. The analysis indicated that the maximum speed and maximum acceleration of the sliding mass were 11.65 m/s and 2.23 m/s 2 , respectively, and that the maximum amplitude and the propagation velocity of the water wave near the landslide were 31.8 m and 18.36 m/s, respectively. Wave run-up investigation indicated that the maximum run-up on shore was 13.1 m, which declined to 1.1 m at Wushan dock 4 km away. The incident causes no casualties, but did result in economic losses of RMB five million. The numerical simulation model GEOWAVE was used to simulate and reproduced the impulse wave generated by the landslide; the results were in good agreement with the observed incident. The numerical simulation data were then applied to analyze the decay and amplification effects of the landslide wave in the river course. The field investigations and witness information provide valuable materials for the studies of landslide kinematics and impulse waves generated by landslides. In addition, the research results provide a useful reference for future similar waves generated by landslides in reservoirs. Content Type Journal Article Category Recent Landslides Pages 1-11 DOI 10.1007/s10346-012-0331-y Authors Bolin Huang, China University of Geosciences, Wuhan, China 430074 Yueping Yin, China Institute for Geo-Environment Monitoring, Beijing, China 100081 Guangning Liu, Wuhan Centre of China Geological Survey, Wuhan, China 430223 Shichang Wang, Wuhan Centre of China Geological Survey, Wuhan, China 430223 Xiaoting Chen, Wuhan Centre of China Geological Survey, Wuhan, China 430223 Zhitao Huo, Wuhan Centre of China Geological Survey, Wuhan, China 430223 Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description: Retraction Note to: Real-time slope water table forecasting by multi-tank model combined with dual ensemble Kalman filter Content Type Journal Article Category Retraction Note Pages 1-1 DOI 10.1007/s10346-012-0321-0 Authors Jun Xiong, Department of Urban and Environmental Engineering, Kyoto University, Kyoto, 615-8540 Japan Tomofumi Koyama, Department of Urban and Environmental Engineering, Kyoto University, Kyoto, 615-8540 Japan Satoshi Nisiyama, Department of Urban and Environmental Engineering, Kyoto University, Kyoto, 615-8540 Japan Yuzo Ohnishi, Department of Urban and Environmental Engineering, Kyoto University, Kyoto, 615-8540 Japan Kenji Takahashi, Department of Urban and Environmental Engineering, Kyoto University, Kyoto, 615-8540 Japan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    The slopes of western Lesser Himalaya (at Sangaldhan Block of Udhampur near Ramban, Jammu and Kashmir India) are being severely affected by tectonic and erosional activities. These activities result in deposit of a thick cover of rock fragments and overburden just above the hard rock. The thickness of overburden cover has directly affected the stability of slope in the study area, though the traditional stability estimation techniques, rock mass rating and slope mass rating, rate this area as moderately stable which does not represent the real stability condition. In this research work, the geotechnical and geophysical surveys have been carried out to reckon the slope stability conditions more accurately as compared to traditional slope stability estimation techniques. A new rating, new slope mass rating, is developed, which gives a better picture of the stability of slopes. It incorporates a new parameter of overburden thickness profile, along with slope angle and other associated factors on the slopes of the mountainous terrains. The vertical electrical sounding surveys were conducted for the demarcation of rock–overburden interface and for determining the overburden cover. This new classification depicts an increase of 12.84 % in unstable slope areas giving a better assessment and factual picture of slope stability in our study area. This study also enumerates the importance of geophysical applications in slope stability studies. The research work is applicable in mountainous terrains such as Himalaya, and the major component of the application is the orientation of overburden or the profile of thickness in relation with slope of surface. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s10346-012-0323-y Authors R. P. Singh, Department of Geology, Centre for Advanced Studies (Environment and Neotectonic Group), University of Delhi, Delhi, 110 007, India C. S. Dubey, Department of Geology, Centre for Advanced Studies (Environment and Neotectonic Group), University of Delhi, Delhi, 110 007, India S. K. Singh, Department of Geology, Centre for Advanced Studies (Environment and Neotectonic Group), University of Delhi, Delhi, 110 007, India D. P. Shukla, Department of Geology, Centre for Advanced Studies (Environment and Neotectonic Group), University of Delhi, Delhi, 110 007, India B. K. Mishra, Department of Geology, Centre for Advanced Studies (Environment and Neotectonic Group), University of Delhi, Delhi, 110 007, India M. Tajbakhsh, Department of Watershed Management, Birjand University, Birjand, Iran P. S. Ningthoujam, Department of Geology, Centre for Advanced Studies (Environment and Neotectonic Group), University of Delhi, Delhi, 110 007, India M. Sharma, Department of Geology, HPU Regional Centre, Dharamshala, Himachal Pradesh, India N. Singh, Department of Geology, Centre for Advanced Studies (Environment and Neotectonic Group), University of Delhi, Delhi, 110 007, India Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    On 20 August 2005, a landslide with a volume of about 400  m 3 occurred at Fu Yung Shan Tsuen, Tsuen Wan in Hong Kong during a severe rainstorm with a return period of about 100  years on a hillside that has been disturbed locally by past human activities. The incident resulted in one fatality and permanent evacuation of residents of four squatter structures in the vicinity. A forensic investigation into the landslide was carried out to review the mechanism and probable causes of the landslide. The key contributory factors in the landslide were diagnosed. The investigation concluded that the landslide was probably caused by the loss of soil suction and transient build-up of groundwater pressure in the near-surface soil materials following prolonged and intense rainfall. The paper presents the methodology adopted for the landslide study, findings of the investigation and the lessons learnt from this fatal landslide. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s10346-012-0332-x Authors K. K. S. Ho, Geotechnical Engineering Office, Civil Engineering and Development Department, Government of the Hong Kong SAR, 101 Princess Margaret Road, Homantin, Kowloon, Hong Kong P. A. Chao, AECOM Asia Company Limited, 20/F Grand Central Plaza, 138 Shatin Rural Committee Road, Shatin, Hong Kong T. M. F. Lau, Geotechnical Engineering Office, Civil Engineering and Development Department, Government of the Hong Kong SAR, 101 Princess Margaret Road, Homantin, Kowloon, Hong Kong S. De Silva, AECOM Asia Company Limited, 20/F Grand Central Plaza, 138 Shatin Rural Committee Road, Shatin, Hong Kong Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    This study outlines the relationship between antecedent precipitations and activation of the translational rock-block slides (TRBSs). This type of landslide has the peculiarity to involve wide sectors of the sedimentary bedrock, and it is emblematic in the Langhe area, in the southern hilly part of Piemonte in the Tertiary Piemonte Basin. The Langhe hills are particularly renowned for the cultivation of valuable vineyards, and therefore, constitute a place of important economic and tourist interest. Furthermore, the high density of structures and infrastructures in this area exposes a number of elements to the activity of these large landslides. In order to minimize human and economic losses, it is particularly important to establish a warning system capable of providing announcement of activation of TRBSs with sufficient advance. In this direction, the Environmental Protection Agency of Piemonte (ARPA Piemonte) developed a precipitation–threshold-based model. The model is set up on an extensive collection of historical data about the landslides movements (since 1917) and the related complete meteorological dataset. The regional weather gauge network and the forecasted precipitation amount, including snow melt’s contribution, provide input data to the model. Output model can be tested by observations derived by the regional landslides monitoring network consisting of inclinometers and groundwater gauges managed by ARPA Piemonte. Content Type Journal Article Category Original Paper Pages 1-18 DOI 10.1007/s10346-012-0319-7 Authors D. Tiranti, Department of Forecasting Systems, Environmental Protection Agency of Piemonte, Torino, Italy D. Rabuffetti, Department of Forecasting Systems, Environmental Protection Agency of Piemonte, Torino, Italy A. Salandin, Department of Forecasting Systems, Environmental Protection Agency of Piemonte, Torino, Italy M. Tararbra, Department of Geology and Geohazards, Environmental Protection Agency of Piemonte, Torino, Italy Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description:    Landslides induced by typhoon Morakot during its passage across Taiwan on 7–9 Aug 2009 claimed more than 700 lives and caused heavy economic loss. Unlike earthquake monitoring, precise locations of landslides could not be determined in near-real time because their seismic phases are difficult to identify. Here, we show that large, damaging landslide events are characterized seismically by a distinct waveform pattern of frequent intermixes of P and S waves over a time window of several tens of seconds. The predominant frequency band during these time windows ranges from 0.5 to 5 Hz. The high-frequency content is clearly deficient relative to that of local earthquakes by about one to two orders. We also demonstrate that large landslide events can be located and monitored with algorithms specifically designed for real-time seismic applications. This near-real-time monitoring capability would be particularly useful for emergency responders and government organizations to coordinate effective relief-and-rescue operations. Content Type Journal Article Category Technical Note Pages 1-7 DOI 10.1007/s10346-012-0322-z Authors Honn Kao, Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sideny, BC V8L 4B2 Canada Chih-Wen Kan, Central Weather Bureau, 64, Gongyuan Road, Taipei, 10048 Taiwan Rong-Yuh Chen, Central Weather Bureau, 64, Gongyuan Road, Taipei, 10048 Taiwan Chien-Hsin Chang, Central Weather Bureau, 64, Gongyuan Road, Taipei, 10048 Taiwan Andreas Rosenberger, Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sideny, BC V8L 4B2 Canada Tzay-Chyn Shin, Central Weather Bureau, 64, Gongyuan Road, Taipei, 10048 Taiwan Pei-Ling Leu, Central Weather Bureau, 64, Gongyuan Road, Taipei, 10048 Taiwan Kai-Wen Kuo, Central Weather Bureau, 64, Gongyuan Road, Taipei, 10048 Taiwan Wen-Tzong Liang, Institute of Earth Sciences, Academia Sinica, 128, Sec. 2, Academia Road, Nangang, Taipei 11529 Taiwan Journal Landslides Online ISSN 1612-5118 Print ISSN 1612-510X

Description: Rock avalanches onto glacier surfaces, involving volumes 1 Mm 3 or more, are common in the glacier environments of NW North America. We analyse the Mount Munday rock avalanche (British Columbia) which occurred in July 1997. It involved the initial movement of 3.2 Mm 3 of granitic gneiss that underwent a high degree of fragmentation as it was emplaced on Ice Valley Glacier as a thin 2.6-km 2 debris sheet. The total height of the path was 850 m, and its length was 4,163 m yielding a fahrböschung of 10°, suggestive of a long runout in relation to volume. Potential energy expended in the movement was calculated as 4.33 × 10 13  J and its specific energy was estimated at 5,204 J/kg. A simulation of the movement using 2D DAN-W and DAN 3D strongly supports the idea that debris sheet geometry (runout and thickness) and behaviour (velocity profile) resulted from movement on a low friction surface (glacier ice). Our analysis of the debris sheet geometry of 23 unconstrained rock avalanches on glacier surfaces in NW North America indicated that the debris sheets are distinct from those in non-glacial environments in that they are (a) longer in relation to volume and (b) more extensive in area in relation to volume. These two effects result in a very thin supra-glacial debris sheet. Using image analysis software, we found that ∼85 % of the initial source rock volume was fragmented to fragment sizes less than 4.7 m 3 in volume during emplacement, and that within the debris sheet, the highest degree of fragmentation is associated with the thinnest debris. In the emplacement of rock avalanche debris sheets on glacier surfaces, the low friction glacier surface drives debris sheet thinning through spreading, which in turn results in the fragmentation of its entire thickness. We thus propose low friction surface-driven fragmentation as a process that contributes to long runout of rock avalanches on glacier surfaces and explains their distinctive debris sheet geometry.

Description: 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.

Description: An ensemble algorithm of data mining decision tree (DT)-based CHi-squared Automatic Interaction Detection (CHAID) is widely used for prediction analysis in variety of applications. CHAID as a multivariate method has an automatic classification capacity to analyze large numbers of landslide conditioning factors. Moreover, it results two or more nodes for each independent variable, where every node contains numbers of presence or absence of landslides (dependent variable). Other DT methods such as Quick, Unbiased, Efficient Statistic Tree (QUEST) and Classification and Regression Trees (CRT) are not able to produce multi branches based tree. Thus, the main objective of this paper is to use CHAID method to perform the best classification fit for each conditioning factors, then, combined it with logistic regression (LR) to find the corresponding coefficients of best fitting function that assess the optimal terminal nodes. In the first step, a landslide inventory map with 296 landslide locations were extracted from various sources over the Pohang-Kyeong Joo catchment (South Korea). Then, the inventory was randomly split into two datasets, 70 % was used for training the models, and the remaining 30 % was used for validation purpose. Thirteen landslide conditioning factors were used for the susceptibility modeling. Then, CHAID was applied and revealed that some conditioning factors such as altitude, soil drain, soil texture and TWI, as terminal nodes and reflected the best classification fit. Then, a proposed ensemble technique was applied and the interpretations of the coefficients showed that the relationship between the decision tree branch nodes distance from drain, soil drain, and TWI, respectively, leads to better consequences assessment of landslides in the current study area. The validation results showed that both success and prediction rates, 75 and 79 %, respectively. This study proved the efficiency and reliability of ensemble DT and LR model in landslide susceptibility mapping.

Description: There is a clear need for integrated research on landslide disaster risk. Landslide disasters have major impacts in developing countries due to the increasing social vulnerability of both rural and urban communities. In recent decades, landslide disasters in Latin America triggered by both precipitation and earthquakes have also increased considerably. Thus, scientific contributions based on integrated risk research are quite urgent for improving the knowledge base for reducing the vulnerability of exposed communities to landslides. Thus, there is a parallel necessity to promote capacity building for young scientists in Latin America by considering the shift of disaster paradigm to recognize the “unnaturalness” of disasters. Under such a framework, there are particular goals to be pursued including: (1) Development of landslide regional networks with a commitment for understanding risk as a socially constructed process; (2) Engagement of young scientists in integrated landslide risk research; (3) Inducing a scientific multi- and transdisciplinary approach for integrated landslide risk research; (4) Development and implementation of capacity building; (5) Contributing to the dissemination and application of common methodologies on landslide disasters investigations; and (6) Strengthening collaboration on integrated landslide disaster risk research in Latin America. In this paper, we present one of the main activities of the ICL Latin-American network in terms of capacity building carried out in 2013; to that end, the first international workshop on forensic investigations of disasters associated with landslides was held in the University of Sciences and Arts of Chiapas in the city of Tuxtla Gutierrez, Chiapas, Mexico, from June 26th to July 4th, 2013.

Description: The gently concave piedmont of the marginal slope of the Flysch Carpathians in the Czech Republic has long been considered to comprise a system of pediments or coalescent alluvial fans. However, within one of the typical sections of this piedmont, large successive landslides with long travel distances of ~2.5 km have been identified through geophysical measurements and the investigation of an extensive artificial exposure. Accelerator mass spectrometry (AMS) radiocarbon dating and pollen analysis demonstrate that the uppermost generations of landslide deposits have originated since ~56 ka BP during the warmer and more humid interpleniglacial conditions of Marine Isotope Stage 3 (MIS 3). The geomorphological evidence for landsliding during MIS 3 has almost completely disappeared from this region due to intensive periglacial processes operating during the Last Glacial Maximum and subsequent fluvial and anthropogenic processes operating during the Holocene. The considerable antiquity of the studied terrestrial landslide bodies is unique within the context of Europe. This study shows the value of re-examining landscape development using new techniques and fresh exposures.

Description: During the five rainy seasons following the 2008 Wenchuan earthquake, at least eight catastrophic events of multiple debris flows occurred in the Yinchanggou area of Baishui River basin, in southwestern China. The deposits had some serious impacts on the transportation, communication, and reconstruction activities. It indicates the start of a period with a high-frequency debris flow activities. In this paper, a detailed review is made of the latest 12 debris flow events, which occurred on 18th August 2012. Field reconnaissance and measurements, supported by a remote sensing interpretation, were conducted to reveal the locations and morphological characteristics of debris flow catchments. A total volume of 50.26 million m 3 co-seismic landslides, triggered by the Wenchuan earthquake, served as source materials for these debris flows and/or shallow landslides. Bedrocks, which were on the hanging wall of the Yingxiu-Beichuan Fault with a mean slope gradient larger than 30°, were the most susceptible for these seism-triggered failures. The volume of debris flow deposits on individual fans vary by many orders of magnitude from 2,900 to 223,500 m 3 . The huge amount of reserves of source material compared to debris flow volumes currently deposited and taking into account the relatively low morphology index values form an indication of the early stage in the development of debris flows and the immense potential for debris flow occurrence in the future. There are two patterns of debris flow initiation which can be distinguished in this study: (a) the channel initiation pattern of concentrated overland flow erosion in the channel beds and (b) the slope initiation pattern which shows the development of new landslides and a transition into debris flows during a heavy rainfall. A catastrophic debris flow in the Haihuiqiao watershed of the Yinchanggou area was selected to show in detail the mechanism of debris flow initiation as a result of intensive erosion in loose debris materials. The critical rainfall threshold in terms of daily precipitation decreased by 77 % compared to the pre-earthquake threshold. A primary rainfall intensity–duration ( ID ) threshold curve was constructed for debris flows for an early-warning system and compared with other global rainfall thresholds. The discussion is focused on the initiation mechanisms of debris flows and the assessment of the critical meteorological threshold.

Description: 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.

Description: The objective of this study was to present an advanced methodology for assessing seismic slope stability by taking into account the uncertainties related to the main input parameters. The methodology was applied on a real landslide in order to show the advantages of using the proposed procedure and establish the baseline trends of dynamic response and calculated permanent seismic displacements. It involves the following steps: preliminary analysis, probabilistic static and seismic factor of safety analysis, and permanent seismic displacement analysis. Estimating post-failure maximum seismic deformation of landslide mass and sounding properties is the most important part of this study. It involves both Newmark sliding block method and continuum mechanics approach, applied for characteristic set of input values in order to have more accurate assessment of slope performance and determine the relative importance of input parameters. The results of the analysis showed the benefits of using the proposed step-by-step methodology. The obtained difference in the results between the two methods depends strongly on the set input data for a particular analysis.

Description: This is the first landslide inventory map in the island of Lefkada integrating satellite imagery and reports from field surveys. In particular, satellite imagery acquired before and after the 2003 earthquake were collected and interpreted with the results of the field survey that took place 1 week after this strong (Mw = 6.3) event. The developed inventory map indicates that the density of landslides decreases from west to east. Furthermore, the spatial distribution of landslides was statistically analyzed in relation to the geology and topography for investigating their influence to landsliding. This was accomplished by overlaying these causal factors as thematic layers with landslide distribution data. Afterwards, weight values of each factor were calculated using the landslide index method and a landslide susceptibility map was developed. The susceptibility map indicates that the highest susceptibility class accounts for 38 % of the total landslide activity, while the three highest classes that cover the 10 % of the surface area, accounting for almost the 85 % of the active landslides. Our model was validated by applying the approaches of success and prediction rate to the dataset of landslides that was previously divided into two groups based on temporal criteria, estimation and validation group. The outcome of the validation dataset was that the highest susceptibility class concentrates 18 % of the total landslide activity. However, taking into account the frequency of landslides within the three highest susceptibility classes, more than 85 %, the model is characterized as reliable for a regional assessment of earthquake-induced landslides hazard.

Description: GIS-based landslide susceptibility maps for the Kankai watershed in east Nepal are developed using the frequency ratio method and the multiple linear regression technique. The maps are derived from comparing observed landslides with possible causative factors: slope angle, slope aspect, slope curvature, relative relief, distance from drainage, land use, geology, distance from faults and mean annual rainfall. The consistency of the maps is evaluated using landslide density analysis, success rate analysis and spatially agreed area approach. The first two analyses produce almost identical quantitative results, whereas the last approach is able to reveal spatial differences between the maps and also to improve predictions in the agreed high landslide-susceptible area.

Description: Rainfall-induced debris flows involving ash-fall pyroclastic deposits that cover steep mountain slopes surrounding the Somma-Vesuvius volcano are natural events and a source of risk for urban settlements located at footslopes in the area. This paper describes experimental methods and modelling results of shallow landslides that occurred on 5–6 May 1998 in selected areas of the Sarno Mountain Range. Stratigraphical surveys carried out in initiation areas show that ash-fall pyroclastic deposits are discontinuously distributed along slopes, with total thicknesses that vary from a maximum value on slopes inclined less than 30° to near zero thickness on slopes inclined greater than 50°. This distribution of cover thickness influences the stratigraphical setting and leads to downward thinning and the pinching out of pyroclastic horizons. Three engineering geological settings were identified, in which most of the initial landslides that triggered debris flows occurred in May 1998 can be classified as (1) knickpoints, characterised by a downward progressive thinning of the pyroclastic mantle; (2) rocky scarps that abruptly interrupt the pyroclastic mantle; and (3) road cuts in the pyroclastic mantle that occur in a critical range of slope angle. Detailed topographic and stratigraphical surveys coupled with field and laboratory tests were conducted to define geometric, hydraulic and mechanical features of pyroclastic soil horizons in the source areas and to carry out hydrological numerical modelling of hillslopes under different rainfall conditions. The slope stability for three representative cases was calculated considering the real sliding surface of the initial landslides and the pore pressures during the infiltration process. The hydrological modelling of hillslopes demonstrated localised increase of pore pressure, up to saturation, where pyroclastic horizons with higher hydraulic conductivity pinch out and the thickness of pyroclastic mantle reduces or is interrupted. These results lead to the identification of a comprehensive hydrogeomorphological model of susceptibility to initial landslides that links morphological, stratigraphical and hydrological conditions. The calculation of intensities and durations of rainfall necessary for slope instability allowed the identification of deterministic hydrological thresholds that account for uncertainty in properties and observed rainfall intensities.

Description: The goals of this work are to show the range of debris-flow volumes and watershed characteristics for several locations, and the differences in flow volumes for events triggered soon after wildfire. A dataset of 929 events was divided into groups based on location and burn status. The three unburned locations show significant differences: debris flows from the Italian Alps are larger and generate more debris per unit basin area or unit channel length than flows in the Western USA or in the Pacific Northwest. However, some of the observed differences may be attributed to the skew of the Italian Alps dataset towards larger events, and the small size and limited range of the Pacific Northwest data. For burned watersheds in the Western U.S. events, there is a clear progression in decreasing volume in debris flows as basins recover from the wildfire: it takes approximately 1 year, or at a few locations, as much as 3 years, for debris production to return to pre-fire rates. The difference is most apparent when the data are normalized for basin area (the area yield, which is 2× larger for burned basins) or for channel length (the length yield, which is 1.6× larger for burned basins). When normalized simultaneously for basin area, channel length, and channel gradient, burned areas produce significantly more debris (2.7–5.4 times as much). Burned areas in the Western USA are more sensitive to wildfire and produce larger debris flows than burned areas in more humid climates such as the Pacific Northwest.

Description: Cheekye River fan is the best-studied fan complex in Canada. The desire to develop portions of the fan with urban housing triggered a series of studies to estimate debris-flow risk to future residents. A recent study (Jakob and Friele 2010 ) provided debris-flow frequency-volume and frequency-discharge data, spanning 20-year to 10,000-year return periods that form the basis for modeling of debris flows on Cheekye River. The numerical computer model FLO-2D was chosen as a modelling tool to predict likely flow paths and to estimate debris-flow intensities for a spectrum of debris-flow return periods. The model is calibrated with the so-called Garbage Dump debris flow that occurred some 900  years ago. Field evidence suggests that the Garbage Dump debris flow has a viscous flow phase that deposited a steep-sided debris plug high in organics in centre fan, which then deflected a low-viscosity afterflow that travelled to Squamish River with slowly diminishing flow depths. The realization of a two-phase flow led to a modelling approach in which the debris-flow hydrograph was split into a high viscosity and low viscosity phase that were modelled in chronologic sequence as two separate and independent modelling runs. A perfect simulation of the Garbage Dump debris flow with modelling is not possible because the exact topography at the time of the event is, to some degree, speculative. However, runout distance, debris deposition and deposit thickness are well known and serve as a good basis for calibration. Predictive analyses using the calibrated model parameters suggest that, under existing conditions, debris flows exceeding a 50-year return period are likely to avulse onto the southern fan sector, thereby damaging existing development and infrastructure. Debris flows of several thousand years return period would inundate large portions of the fan, sever Highway 99, CN Rail, and the Squamish Valley road and would impact existing housing development on the fan. These observations suggest a need for debris-flow mitigation for existing and future development alike.

Description: The wired and wireless monitoring system installed in the Rebaixader catchment detected six debris flows and 11 debris floods between 2009 and 2012. Apart from results directly related to the processes, many experiences associated with monitoring were collected. Debris flows and debris floods showed clear differences in both the recorded data and field observations. The distinction was especially visible in the stage measurements and the ground vibration registered by the most downstream geophone. At this geophone, a positive relation between the maximum ground vibration and the volume was also observed. The triggering of most events was associated with short, high-intensity rainstorms in summer, but some were also generated in spring, when the melting of snow cover and frozen soil played an additional role. A positive correlation between the volume and both the amount and the intensity of the triggering rainfall was observed. Regarding technical aspects, a switch between a “no-event” mode with a low sample rate and an “event” mode with a fast sampling was particularly useful at the station that register the passing of a flow. In addition, the stations, which most recently were installed at Rebaixader, apply wireless devices because wireless techniques include multiple advantages against standard wired systems. Although recorded data or even video images provide detailed information on the debris-flow behavior, we strongly recommend periodic field surveys along the entire torrent to verify and improve the interpretation obtained from the monitoring system.

Description: Rockslides in alpine areas can reach large volumes and, owing to their position along slopes, can either undergo large and rapid evolution originating large rock avalanches or can decelerate and stabilize. As a consequence, in particular when located within large deep-seated deformations, this type of instability requires accurate observation and monitoring. In this paper, the case study of the La Saxe rockslide (ca. 8 × 10 6  m 3 ), located within a deep-seated deformation, undergoing a major phase of acceleration in the last decade and exposing the valley bottom to a high risk, is discussed. To reach a more complete understanding of the process, in the last 3 years, an intense investigation program has been developed. Boreholes have been drilled, logged, and instrumented (open-pipe piezometers, borehole wire extensometers, inclinometric casings) to assess the landslide volume, the rate of displacement at depth, and the water pressure. Displacement monitoring has been undertaken with optical targets, a GPS network, a ground-based interferometer, and four differential multi-parametric borehole probes. A clear seasonal acceleration is observed related to snow melting periods. Deep displacements are clearly localized at specific depths. The analysis of the piezometric and snowmelt data and the calibration of a 1D block model allows the forecast of the expected displacements. To this purpose, a 1D pseudo-dynamic visco-plastic approach, based on Perzyna’s theory, has been developed. The viscous nucleus has been assumed to be bi-linear: in one case, irreversible deformations develop uniquely for positive yield function values; in a more general case, visco-plastic deformations develop even for negative values. The model has been calibrated and subsequently validated on a long temporal series of monitoring data, and it seems reliable for simulating the in situ data. A 3D simplified approach is suggested by subdividing the landslide mass into distinct interacting blocks.

Description: Landslide displacement is widely obtained to discover landslide behaviors for purpose of event forecasting. This article aims to present a comparative study on landslide nonlinear displacement analysis and prediction using computational intelligence techniques. Three state-of-art techniques, the support vector machine (SVM), the relevance vector machine (RVM), and the Gaussian process (GP), are comparatively presented briefly for modeling landslide displacement series. The three techniques are discussed comparatively for both fitting and predicting the landslide displacement series. Two landslides, the Baishuihe colluvial landslide in China Three Georges and the Super-Sauze mudslide in the French Alps, are illustrated. The results prove that the computational intelligence approaches are feasible and capable of fitting and predicting landslide nonlinear displacement. The Gaussian process, on the whole, performs better than the support vector machine, relevance vector machine, and simple artificial neural network (ANN) with optimized parameter values in predictive analysis of the landslide displacement.

Description: Majority of landslides in the Indian sub-continent are triggered by rainfall. Several attempts in the global scenario have been made to establish rainfall thresholds in terms of intensity-duration and antecedent rainfall models on global, regional and local scales for the occurrence of landslides. However, in the context of the Indian Himalayas, the rainfall thresholds for landslide occurrences are not yet understood fully. Neither on regional scale nor on local scale, establishing such rainfall thresholds for landslide occurrences in Indian Himalayas has yet been attempted. This paper presents an attempt towards deriving local rainfall thresholds for landslides based on daily rainfall data in and around Chamoli-Joshimath region of the Garhwal Himalayas, India. Around 128 landslides taken place in last 4 years from 2009 to 2012 have been studied to derive rainfall thresholds. Out of 128 landslides, however, rainfall events pertaining to 81 landslides were analysed to yield an empirical intensity–duration threshold for landslide occurrences. The rainfall threshold relationship fitted to the lower boundary of the landslide triggering rainfall events is I  = 1.82 D −0.23 ( I  = rainfall intensity in millimeters per hour and D  = duration in hours). It is revealed that for rainfall events of shorter duration (≤24 h) with a rainfall intensity of 0.87 mm/h, the risk of landslide occurrence in this part of the terrain is expected to be high. Also, the role of antecedent rainfall in causing landslides was analysed by considering daily rainfall at failure and different period cumulative rainfall prior to failure considering all 128 landslides. It is observed that a minimum 10-day antecedent rainfall of 55 mm and a 20-day antecedent rainfall of 185 mm are required for the initiation of landslides in this area. These rainfall thresholds presented in this paper may be improved with the hourly rainfall data vis-à-vis landslide occurrences and also data of later years. However, these thresholds may be used in landslide warning systems for this particular region of the Garhwal Himalayas to guide the traffic and provide safety to the tourists travelling along this pilgrim route during monsoon seasons.

Description: This paper presents a new methodology for ex post assessment of direct landslide costs for transportation infrastructures. The methodology includes tools to compile, model, and extrapolate landslide losses on different spatial scales over time. A landslide susceptibility model enables regional cost extrapolation by means of a cost figure obtained from local cost compilation for a representative case study area. On a local level, cost survey is closely linked with cost modeling, a toolset for cost estimation based on landslide databases. Cost modeling uses landslide disaster management process models (LDMMs) and cost modules to simulate and monetize cost factors for certain types of landslide damage. The landslide susceptibility model provides a regional exposure index and updates the cost figure to a cost index which describes the costs per kilometer of traffic route at risk of landslides. Both indexes enable the regionalization of local landslide losses. The methodology is applied and tested in a cost assessment for highways in the Lower Saxon Uplands, NW Germany, in the period 1980 to 2010. In this 7,400-km 2 large mountain region, 77 km of highway is located in landslide hazard area. Annual average costs of US$52,000 per km of highway at risk of landslides are identified as cost index for a local case study area. The cost extrapolation results in annual average costs for highways in the Lower Saxon Uplands of US$4.02 million. This test application as well as a validation of selected modeling tools verifies the functionality of this methodology.

Description: Massive rock avalanches form some of the largest landslide deposits on Earth and are major geohazards in high-relief mountains. This work reinterprets a previously reported glacial deposit in the Alai Valley of Kyrgyzstan as the result of an extremely long-runout, probably coseismic, rock avalanche from the Komansu River catchment. Total runout of the rock avalanche is ~28 km, making it one of the longest-runout subaerial non-volcanic rock avalanches thus far identified on Earth. This runout length appears to require a rock volume of ~20 km 3 ; however, the likely source zone in the Trans Alai range likely contained just ~4 km 3 of rock, and presently, the deposit has a volume of only 3–5 km 3 ; a pure rock avalanche volume of 〉10 km 3 is therefore impossible, so the event was much more mobile than most non-volcanic rock avalanches. Explaining this exceptional mobility is crucial for present-day hazard analysis. There is unequivocal sedimentary evidence for intense basal fragmentation, and the deposit in the Alai Valley has prominent hummocks; these indicate a rock avalanche rather than a rock-ice avalanche origin. The event occurred 5,000–11,000 yr B.P., after the region’s glaciers had begun retreating, implying that supraglacial runout was limited. Current volume—runout relationships suggest a maximum runout of ~10 km for a 4-km 3 rock avalanche. Volcanic debris avalanches, however, are more mobile than non-volcanic rock avalanches due to their much higher source water content; a rock avalanche containing a similarly high water content would require a volume of about 8 km 3 to explain the extreme runout of the Komansu event. Rock and debris avalanches can entrain large amounts of material during runout, with some doubling their initial volume. The best current explanation of the Komansu rock avalanche thus involves an initial failure of ~4 km 3 of rock debris, with high water content probably deriving from large glaciers on the edifice that subsequently entrained ~4 km 3 of valley material together with further glacial ice, resulting in a total runout of 28 km. It is as yet unclear whether glacial retreat has rendered a present-day repetition of such an event impossible.

Description: The Son Poc rockfall took place on the 6th of March 2013 in the municipality of Bunyola, on the southern side of the Tramuntana Range (Mallorca) and after a rainy and cold period on the region. A volume of rock of 4.000 m 3 was detached from the cliff crowning the peak falling down by toppling. The impact of the boulder caused its fragmentation, and numerous boulders bounced and rolled downslope with volumes from 1 to 35 m 3 , following two trajectories: southwest (SW) and southeast (SE). The SE trajectory, with a larger runout (376 m), reached an urban area, where some of the boulders hit the roofs and walls of nearby houses, stopping others in their gardening areas. Fortunately, no fatalities occurred despite of the presence of some people at that moment, but the event caused great concern in a region which lives from and for tourism. The Son Poc rockfall has been simulated using RocPro3D software which uses GIS technology to produce 3D rockfall trajectories lines, estimated velocity and energy of falling blocks, as well as bounce heights, impacts, and stopping points. The results are in agreement with field observations and with a very good accuracy between real and modeled outcomes.

Description: Permafrost decline, observed in the last few decades as a result of climate change, causes an activation of cryogenic landslide processes. This study on Olkhon Island in Lake Baikal (Eastern Siberia), located within the discontinuous permafrost zone, was aimed to determine how strongly the landslide forms found there are associated with climatic conditions and if they can react to climate change. It was also important to identify which type of landslides in this area is the most sensitive indicator of the observed changes and to what extent they can react to them. For this purpose, landslides were identified, and their morphology, geological structure, and thermal parameters were assessed. The results show that the key process is the increase in thickness of the active layer, partly due to the presence of Miocene lake clays and changes in water level in Lake Baikal.

Description: This paper focuses on characteristics of debris flows from the lower part of the Lotru River basin (South Carpathians, Romania). The damage produced by these debris flows has included burial of agricultural land, roads covered by debris flows, and even the obstruction of the Lotru River. Simple statistical analysis has been used to emphasize the characteristics of the debris flow sites. The collected data show that heavy rainfall is the main triggering mechanism of debris flow events in the Lotru hydrographic basin. The daily rainfall data for this region show that important debris flow events generally occur when rainfall exceeds 40 mm in 24 h, while rainfall levels between 25 and 40 mm in 24 h result in hyperconcentrated flows. For 11 of 14 studied debris flow sites, the fan area is greater than the source area, probably due to the thickness of the regolith, which is up to 5–10 m deep. Both source area and deposition area are very dynamic. The retreat rate calculated for five debris flow sites ranges from 5 to 30 m in 30 years (from 1975 to 2005). Channel cross section measurements on one of the debris flows show that velocity values vary from 1.31 to 2.64 m/s; corresponding discharge values vary from 4 to 10.03 m 3 /s.

Description: Existence of soil pipes is reported in many collapsed slopes indicating their influences on landslide initiation. Flume model tests with different soil pipe configurations, (a) no pipe, (b) closed pipe and (c) open pipe, were conducted to understand the influence of soil pipes on slope stability during rainfall. Porewater pressures, discharges through the soil pipe and seepage from the slope end were recorded. Open pipe works as a hillslope drainage and reduces the porewater pressure of an entire slope, but if blocked, porewater pressure close to the lower end of pipe rises up rapidly, leading to immediate soil mass movement. Average hillslope saturation at the time of failure in a hillslope with “initially open but later blocked” pipe is lower than that in other cases. Discharge measurement shows that soil pipe even if ended within the hillslope, increases hillslope discharge. In all the three cases of experiments, shallow retrogressive sliding occurred. However, backward progress is faster in the hillslope without soil pipe because of more uniform distribution of moisture throughout the slope than the other two cases. The simple numerical analysis developed is able to predict the timing of the first crack for piped and no-piped hillslope.

Description: Downie Slide has been interpreted as a massive, composite rockslide, and a number of landslide zones have been defined based on the interpretation of morphological features and a detailed assessment of spatially discriminated slope behaviour. Key factors controlling the mechanics of massive slow-moving landslides can be interpreted through the observation and detailed study of the slope behaviour and physical characteristics. Once identified, key components influencing slope deformation can be tested using three-dimensional numerical models. Two series of numerical simulations have been developed to test how explicitly defined internal shear zones, and the interaction between landslide morphological regions, influence global landslide behaviour. Results from these numerical simulations, when compared to field monitoring data, indicate that internal shear zones have little influence on Downie Slide deformation, while the interaction between morphological zones plays a larger role in slope kinematics.

Description: A debris-flow hazard assessment was conducted for the Medano Creek drainage basin, at Great Sand Dunes National Park and Preserve, following the 2,400  ha Medano Fire in 2010. Debris-flow probability and volume predictions were made using empirical regression models. Model parameters include burn severity, rainfall intensity, topographic characteristics, and soil properties. Model results provided park resource managers with information on potential sub-basin-specific hazards to park visitors, roads, and campsites. Monitoring of the first significant rainfall events following the fire and the resulting debris-flow responses provided means for model validation. Of the three probability models utilized, two predicted high probability of debris-flow occurrence for all sub-basins that produced debris flows, with numerous false positives, while the third failed to predict high probability in any of the sub-basins. The volume model predicted volumes within approximately one order of magnitude higher than those measured.

Description: This paper illustrates the quantitative estimation of specific risk (i.e., the product of hazard and vulnerability) for 39 buildings located upon the Ancona landslide based on the characterization of landslide kinematics presented in a companion paper. Hazard is quantified based on intensity, intended as the damaging potential of the kinetic and/or geometric attributes of the landslide, and is expressed in terms of expected exceedance of preset cumulative displacement thresholds for a set of five reference time intervals, ranging from 1 to 100 years. The estimation of hazard relies sequentially on (1) Monte Carlo simulation of displacement series, with sampling distributions of average yearly displacement defined on the basis of the statistical processing of inclinometer and radar interferometer data; and (2) the subsequent spatialization of displacement using radial basis interpolation as described in the companion paper. The vulnerability of the set of buildings relies on a quantitative model in which vulnerability is a function of landslide intensity and the resilience of the buildings. Resilience is a function of a set of indicators including structural type, age, and foundation type and is temporally variable due to the progressive structural degradation. Hazard, vulnerability, and specific risk are estimated for the set of five aforementioned reference time intervals. The magnitude and temporal dependence of hazard, vulnerability, and specific risk are assessed critically.

Description: The rehabilitation construction in the reservoir area of Xiangjiaba hydropower station in Southwest China has caused many landslides. A shallow progressive failure that occurred on the resettlement site of Xin’an Town of Pingshan County in Sichuan Province was selected as a case study. This landslide occurred in a long and gently inclined area by slope excavation under rainfall conditions. It is about 3.0 m deep with a total length of 35 m and is composed of some subfailures. Undisturbed samples were retrieved, on which the basic properties, shear strength, expansive potential, mineral compositions, and microstructures were tested and analyzed. The results show (1) the landsliding materials belong to medium expansive soil, consisting of the clay minerals of illite–smectite (I/S) and chlorite–smectite (C/S); (2) shear strength of the soil is sensitive to water, which greatly decreases once saturated; and (3) many fractures and relatively large pores are developed in the soils. Back analysis of the landslide shows that the shear strength at failure is less than the residual shear strength obtained from lab tests, indicating that some processes contributing to the slope failure could not be reflected by the shear box test. Based on the above analysis, the progressive process of the slope failure was interpreted, and it is inferred that the rainfall entered into the slope mainly through fractures and relatively large pores in the soil. It caused not only the great decrease in soil strength but also the swelling trend. The latter one would lead to growth, interaction, and coalescence of the fractures. Soon after, these fractures formed the shear planes (zones), which further decreased the resistance of the landslide. Under these favorable conditions, the slope excavation directly triggered the failure.

Description: Hummocks are topographic features of large landslides and rockslide-debris avalanches common in volcanic settings. We use scaled analog models to study hummock formation and explore their importance in understanding landslide kinematics and dynamics. The models are designed to replicate large-scale volcanic collapses but are relevant also to non-volcanic settings. We characterize hummocks in terms of their evolution, spatial distribution, and internal structure from slide initiation to final arrest. Hummocks initially form by extensional faulting as a landslide begins to move. During motion, individual large blocks develop and spread, creating an initial distribution, with small hummocks at the landslide front and larger ones at the back. As the mass spreads, hummocks can get wider but may decrease in height, break up, or merge to form bigger and long anticlinal hummocks when confined. Hummock size depends on their position in the initial mass, modified by subsequent breakup or coalescence. A hummock has normal faults that flatten into low-angle detachments and merge with a basal shear zone. In areas of transverse movement within a landslide, elongate hummocks develop between strike–slip flower structures. All the model structures are consistent with field observations and suggest a general brittle-slide emplacement for most landslide avalanches. Absence of hummocks and fault-like features in the deposit may imply a more fluidal flow of emplacement or very low cohesion of lithologies. Hummocks can be used as kinematic indicators to indicate landslide evolution and reconstruct initial failures and provide a framework with which to study emplacement dynamics.

Description: This paper proposes a hydro-geomechanical finite element model to reproduce the kinematic behaviour of large slow landslides. The interaction between solid skeleton and pore fluids is modelled with a time dependent u – p w formulation and a groundwater model that takes into account recorded daily rainfall intensity. A viscoplastic constitutive model based on Perzyna’s theory is applied to reproduce soil viscous behaviour and the delayed creep deformation. The proposed model is applied to Portalet landslide (Central Spanish Pyrenees). This is an active paleo-landslide that has been reactivated by the construction of a parking area at the toe of the slope. The stability analysis reveals that, after the constructive solutions were undertaken, the slope is in a limit equilibrium situation. Nevertheless, time-dependent analysis reproduces the nearly constant strain rate (secondary creep) and the acceleration/deceleration of the moving mass due to hydrological changes. Overall, the model reproduces a 2-m displacement in the past 8  years that coincides with in situ monitoring data. The proposed model is useful for short- and mid-term predictions of secondary creep. However, long-time predictions remain uncertain, stability depends strongly on the position of the water table depth and new failures during tertiary creep due to soil temporal microstructural degradation are difficult to calibrate.

Description: Dam-breaches that cause outburst floods may induce downstream hazards. Because landslide dams can breach soon after they are formed, it is critical to assess the stability quickly to enable prompt action. However, dam geometry, an essential component of hazard evaluation, is not available in most cases. Our research proposes a procedure that utilizes post-landslide orthorectified remote sensing images and the pre-landslide Digital Terrain Model in the Geographic Information System to estimate the geometry of a particular dam. The procedure includes the following three modules: (1) the selection of the reference points on the dam and lake boundaries, (2) the interpolation of the dam-crest elevation, and (3) the estimation of dam-geometry parameters (i.e., the height, length, and width), the catchment area, the volumes of barrier lake and landslides dam. This procedure is demonstrated through a case study of the Namasha Landslide Dam in Taiwan. It was shown the dam-surface elevation estimated from the proposed procedure can approximate the elevation derived from profile leveling after the formation of the landslide dam. Thus, it is feasible to assess the critical parameters required for the landslide dam hazard assessment rapidly once the ortho-photo data are available. The proposed procedure is useful for quick and efficient decision making regarding hazard mitigation.

Description: The primary objective of this paper is to present a semiautomatic procedure that, integrated with traditional methods, can be useful for a rapid definition of rock fall susceptibility scenarios with the purpose of civil protection. Due to its morphology (steep slopes and narrow valleys), regional seismicity, and rock mass characteristics, the Nera Valley (Valnerina, Umbria Region, Italy) is characterized by high rock fall risk. With the aim of covering a wide range of features and investigating the main advantages and drawbacks of the proposed approach, data collection (terrestrial laser scanning (TLS) and geomechanical surveys) was carried out at three different slopes. Detailed three-dimensional (3D) models were created to reconstruct the shape and volume of the most unstable blocks, to define the position of the main rock fall source areas, and to precisely distinguish the outcropping materials and the position of the elements at risk for reliable runout analyses. The proposed approach can be useful in supporting proper maintenance and land management programs both in ordinary and in emergency circumstances.