Advancing Culture of Living with Landslides

Sub-theme 5.1 focuses on the interaction of landslides in natural and engineered slopes with the built environment. The associated socio-economic issues are particularly important given population growth and the associated demand for new and enhanced infrastructure. The papers included herein provide a wide-ranging overview of methodologies and techniques that can be used to identify the effects of landslides on buildings, infrastructure and large engineering works, as well as cultural heritage.

This paper presents an overview of the findings from a series of country-scale landslide risk assessments conducted on behalf of the governments of five Sub-Saharan countries, the World Bank and the Global Facility for Disaster Reduction and Recovery (GFDRR). Ethiopia, Kenya, Uganda, Niger and Senegal sample a wide range of Sub-Saharan Africa’s different geographies and are characterised by contrasting levels of development. Landslide hazard, exposure and vulnerability therefore differ from country to country, resulting in significant spatial variation of landslide risk. In East Africa; Ethiopia, Kenya and Uganda are characterised by mountainous and seismically active terrain which results in a relatively high landslide hazard. In conjunction with rapid urbanisation and a population which is expected to rise from around 170 million in 2010 to nearly 300 million in 2050, this means that landslides pose a significant risk to the built environment. In West Africa, a combination of low landslide hazard and lower exposure in Niger and Senegal results in comparatively low landslide risk. This paper also describes areas with perceived misconceptions with regard to the levels of landslide risk. These are areas of only low to moderate landslide hazard but where urbanisation has resulted in a concentration of exposed buildings and infrastructure that are vulnerable to landslides, resulting in higher landslide risk.

Rainfall-induced debris flows frequently cause disruption to the Scottish road network. A regional assessment of debris flow hazard and risk allows risk reduction actions to be targeted effectively. To this end a strategic approach to landslide risk reduction, which incorporates a classification scheme for landslide management and mitigation has been developed, in order to provide a common lexicon (or group of words) that can be used to describe goals, outcomes, approaches and processes related to risk reduction, and to allow a clear focus on those goals, outcomes and approaches. The focus is thus first on the desired outcome from risk reduction: whether the exposure, or vulnerability, of the at-risk infrastructure and people (and their associated socio-economic activities, which may be impacted over significant areas) is to be targeted for reduction or whether the hazard itself is to be reduced (either directly or by affecting the physical elements at risk).

The landslide risk for the entire Czech road network is presented here. The risk was computed using data on landslide hazard and data on potential impacts of road blockage. Data from the official landslide database were used for landslide hazard computation combined with data from historical records on roads interrupted by landsliding. Vulnerability was computed as direct costs which are related to road construction costs and indirect costs. The latter express additional economic losses from the blocked roads. This concept was applied at II/432 road link as a case study where a landslide interrupted traffic in May 2010. Indirect losses were estimated as being 2.5 times higher than costs related to mitigation works. All data can be viewed at rupok.cz website.

We examine how large, slow moving landslides impact urban house prices in three areas of England and Wales. 12,663 house transaction values were analysed covering all house sales 1995–2012 in Lyme Regis, Dorset; Ventnor, Isle of Wight and Merthyr Tydfil, Glamorgan. Values were analysed with respect to local landslide events and visible landslide damage. In all three study areas, individual landslide events caused little or no negative impacts on nearby property prices, though remediation is likely to have short-term positive impacts on local house prices. Localised blight and suppressed house prices to a distance of 75 m was found in areas affected by ongoing incipient movement. By comparison with other sources of property blight, the radius of influence is 25% of that expected from an abandoned property or electricity pylon and less than 5% that of a windfarm. The socio-economic environment was important in determining the degree of house price impact of landslide events and for most locations, landslides form only a minor impact compared to other factors.

The paper presents slope instabilities together with monitoring and counteraction techniques in lignite opencast mines. It includes examples of landslides in two of the largest open-pit mines and external spoil dumps in Poland. The Belchatow mine, one of the largest excavations in Europe, is located in the central part of Poland and has lignite resources of 2 bln tons and an annual production of 42 mln tons. Landslides are registered there every year. The largest with a volume of a few thousand to 3.5 mln m3 with displacements of 2 mm-2 m per day. In the past, similar threats have occurred at the Turow mine, the second largest in Poland. It is located in the Lower Silesia District, close to the German and Czech borders. Its estimated lignite reserves are equal to 760 mln tons, with an annual production of 27.7 mln tons. In previous years, the author of this paper had the opportunity to participate in parts of landslide investigations at these mines. The research included CPTU in situ tests, laboratory tests, displacement monitoring and numerical modelling. It was difficult to come up with an interpretation of soil strength parameters. Dump soils varied in strength due to their anthropogenetic nature. The interpretation of the clayey soils parameters in the pit was complicated because of high preconsolidation and partial saturation. The new Euracoal Slopes Project conducted by an international consortium of six European countries aims for the practical implementation of new geotechnical monitoring methods. Complementary methods should allow for better prediction of landslide activity. PSI interferometry, UAV and ground-based laser scanning, in situ monitoring, shallow geophysics and laboratory triaxial and centrifuge testing should deliver new data for slope stability analysis. Although the mines have advanced monitoring systems and remediation procedures, the full elimination of hazards in mines of this size and depth is not possible.

Urban issues are increasingly prominent on the national policy agenda in Austria. The biggest policy challenges consist of the development of an integrated evaluation of the threats and risks (security level, protection objectives), in the preparation of accepted standards for the consideration of landslides as well as their use in spatial planning (ÖROK 2015). The Austrian Concept on Spatial Development (ACSD), which is a strategic instrument for federal policies in regional development, was set up to create a new cooperation at expert level and to develop basic approaches for key issues in an interdisciplinary forum. The ACSD-partnership for “Risk management for gravitative natural hazards” in spatial planning concerning slope processes (landslides including rock falls) was established in 2012 under the leadership of the Federal Ministry for Agriculture, Forestry, Environment and Water Management and Geological Survey of Austria to bridge the gap between geohazard mapping, risk management and spatial planning for these relevant phenomena. The results of this partnership are based on working papers produced by the working groups Spatial Planning, Geology and Sectoral Planning. The activities of the working group “Geology”, presented in this paper, consisted in the evaluation of the existing methods for the calculation of landslide susceptibility (and rock falls) and the impact area in terms of their suitability as well as in the creation of standards and guides to draw up susceptibility maps for spatial planning. Further recommendations are given in terms of the quality assurance, uncertainties, model validation and traceability.

The Rest and be Thankful (A83) in Scotland has been subject to frequent landslide activity in recent years and the trunk road has gained a reputation as one of the most active landslide sites in the UK. An average of two road closures per annum has been recorded over the last five years. This paper compares the site with other locations in Scotland that are prone to debris flows and explores a range of geomorphological factors using high resolution Terrestrial Laser Scanning data. The site is found to be relatively active, although normalization for mean annual rainfall makes activity at the site comparable to the likes of the Drumochter Pass. Macro-scale slope morphology is found to correspond strongly with the spatial distribution of recent activity. Channelisation is considered to be a significant factor in the overall debris flow hazard by confining flow and enabling entrainment. This was demonstrated during two recent events that mobilized at high elevations and entrained significant volumes of material along long runout paths.

Deep-seated Gravitational Slope Deformations (DsGSDs) are widespread phenomena in mountain regions. In the Valle d’Aosta alpine region of northern Italy, DsGSDs occupy 13.5% of the entire regional territory. A total of 280 phenomena have been inventoried in the IFFI (Italian Landslide Inventory) project. These large slope instabilities often affect urbanized areas and strategic infrastructure and may involve entire valley flanks. The presence of settlements on DsGSDs has led the regional Geological Survey to assess the possible effects of these phenomena on human activities. This study is aimed at implementing a methodology that is based on interpreting Synthetic Aperture Radar (SAR) data for recognizing the most active sectors of these phenomena. Starting from the available RADARSAT−1 dataset, we attempt to propose a methodology for the identification of the main morpho-structural domains that characterize these huge phenomena and the definition of different sectors that make up the DsGSDs, which are characterized by different levels of activity. This subdivision is important for linking the different kinematic domains within DsGSDs with the level of attention that should be given to them in the studies that support the request for authorization of new infrastructure. We apply this method to three case studies that represent significant phenomena involving urban areas within the Valle d’Aosta region. In particular, we analyze study areas containing the Cime Bianche DsGSD, the Valtourenenche DsGSD, and the Quart DsGSD. These phenomena have different levels of evolution that are controlled by the interaction of diverse factors, and involve buildings and other infrastructure. This setting has been useful for testing the development of the methodology, which takes advantage of remote-sensing investigations, together with the local geological, geomorphological and structural setting of each case study that we analyzed. This method aims to produce a useful method for delineating guidelines for the building of new infrastructure, in support of the Regional Agency.

The remaining buildings of Gediminas’s Castle in Vilnius stand on the top of a 40 m high hill composed of Quaternary glacial, glaciolacustrine, glaciofliuvial inter-layered deposits and technogenic (cultural layer) accumulations. The city center and castles are located in an area at the very margin at the maximum advance of the Weichselian glaciation. There was no direct erosion impact in the area of Vilnius’s hills from meltwater for the formation of the upper reaches of the highest ravines. Therefore, it is proposed that the main features of the Vilnius Castles hills were formed by periglacial thermal erosion—the movement of land masses due to the thawing of permafrost at a time of climate change and the beginning of the vanishing of the Weichselian ice body. Over the course of history people reshaped the slopes of these hills for living and defense purposes. The saddle connecting Gediminas’s Hill and the massif of the Hill of Three Crosses goes back to historical times when the artificial channel for the Vilnia River was dug and it became a separate hillfort. Due to the steep slopes of the hills, slope deformations and landslides have been occurring since the historical past until the present. Recently a landslide formed on the eastern slope in 2004 and reactivated in 2008. In early spring of 2016 two new landslides appeared on the northwestern slope preceded by a number of cracks on the ground surface. Causes of slopes failure and general problems of stabilization are dealt with this article, also covered is the necessity of early warning system installation, slopes surfaces permanent monitoring based on 3D laser scanning, etc.

This paper presents the approach, hereafter named “dual approach”, applied in reducing risks of roadworks-related landslides, based on the preliminary landslide assessment and the Observational Method (OM). This approach has been implemented to the design of a 110 km motorway project in Algeria, during the last 10 years. The North-South oriented alignment of this motorway crosses different environments starting from the plain area of the Djen Djen valley, passing through a very irregular and geomorphological composite area of the “Petit Kabylie” massif, up to the future connection with the existing East-West Highway. The geological context is characterized by the presence of several complex rock formations, including heterogeneous rock masses as Flysch. These rock formations are strongly deformed and weathered such that landslide occurrence can be often related to the poor unfavorable geological, structural and geotechnical conditions. Roadworks design and construction in such complex and irregular mountainous areas are faced with various and significant natural hazards including large extended landslides. The parallelism of and partial superimposition between the design and the construction phase had mainly two consequences; notwithstanding the fact it forced the timing of the two phases, on the other hand, it allowed designers to quickly update the base reference model and design choices in several cases, with significant improvements and advantages in terms of time and cost.

The active Irazú Volcano is the highest of several composite volcanic cones which make up the Cordillera Central in Costa Rica, close to the city of Cartago. The top of the volcano is strategic for the Country, since at the height of over 3400 m sit 84 telecommunication towers used by government agencies and several TV and radio stations, which guarantee the station coverage of more than 60 percent of the national territory. Since December 2014, a series of minor tremors, or microseisms, occurred at the Irazú and some open and deep fissures formed on the upper part of the volcano associated with formation of landslides. More research is needed to determine if these fissures are directly related to recent seismic activity. However, the landslide formation has made it necessary to relocate the towers and there is evidence of the possible destabilization of a volume of about 3.5 million cubic meters of material. In particular, if the landslide triggers in conjunction with heavy rains the movement could evolve into a huge debris flow that could affect Cartago city, similar to the debris flow disaster of December 1963. The dynamics of this potential event have been analyzed using the numerical code RASH3D. The calculated flow intensities and flow paths could be used to support hazard mapping and the design of mitigation measures. The reliability of the obtained results are a function of assumptions regarding source areas, magnitudes of possible debris flows and calibration of rheological characteristics, but also digital terrain model (DTM) quality. As to this last aspect, a systematic comparison of numerical results, DTM and air photos enabled identification of various weak points of the digital terrain model and identified potentially critical zones due to the presence of man-made structures.

Landslides are the most common geomorphic hazard processes in Sub-Carpathians regions. Crossing the Getic Sub-Carpathians between Campulung Muscel city (the first royal residence of Romanian Country) and Ramnicu Valcea city, the 73C National Road is constructed for more than 90% on sloping surfaces. A wide variety of landslide types, a high landslide frequency (over 5 landslides reactivations/year and other new triggering) and a high density (between 0.5 and 3.3 landslides/km) are the main characteristics of the slope instability along the 73C National Road. Many stabilisation and repair works have been completed, but different section remain vulnerable to landslide damage. The study aims are to map the different types of landslides, to identify the landslides causes and their impact of landslides related to 73C National Road and its communities, to identify new morphological surfaces which may have a high landslide susceptibility at and to assess the impact of landslides. The main causes of landslides along 73C National Road are hydrogeologically controlled and are linked to high degree of drainage density and deforestation. A multy-disciplinary approach was taken, consisting: landslides mapping, historical maps analysis, geomorphological and geophysical methods, topographic and geotechnical surveys. The results highlight considerable vulnerability of slope stabilisation works as a consequence of an incomplete understanding of landslide processes and limited stabilisation works involving just the road embankment.

This paper aims to detecting terrain movements in landslide-affected and landslide-prone zones and their damaging effects on the urban fabric. The case study is the Volterra area in Tuscany region (Italy), covers about 20 km2 and is extensively affected by diffuse slope instability. Firstly, the spatial distribution and types of the landslides were studied on the basis of the geological and geomorphological setting coupled with a geotechnical monitoring. Secondly, satellite SAR (Synthetic Aperture Radar) images acquired by ENVISAT and COSMO-SkyMed sensors respectively in 2003–2009 and 2010–2015 and processed with Persistent Scatterer Interferometry (PSI) techniques, were exploited. In particular, these satellite radar data combined with thematic data and in situ field surveys allowed the improvement of the geometric and kinematic characterization of landslides, as well as allowing a deformation and damage assessment to be undertaken on built-up zones. The classification of damage degree and building deformation velocity maps of the study area were also evaluated through PSI displacement rates. Furthermore, as a single building-scale analysis, maximum differential settlement parameters of some sample buildings were derived from radar measurements, and then cross-compared with constructive features, geomorphological conditions and with field evidences of known landslide areas. This work allowed the correlation of landslide movements and their effects on the urban fabric and provided a useful stability analysis within future risk mitigation strategies.

The aim of this study is to describe the modifications of the built environment that have occurred in 36 years following the Irpinia-Basilicata, 1980 earthquake. In particular, especially in the villages of the epicentral area, changes in the urban and territorial setting have been examined, as well as the consequences of ground effects that have influenced the choices of reconstruction, both in situ, and far from the original historical centers. The November 23, 1980 Irpinia–Basilicata earthquake (Mw = 6.9; Io = X MCS; Io = X ESI-07), killing 3000 people, hit 800 localities over a large area of Southern Italy; 75,000 houses totally collapsed and 275,000 were badly damaged. The earthquake induced primary and secondary environmental effects, over all slope movements. The total amount of surface faulting was 40 km in length with the maximum displacement of 100 cm; the total area affected by slope movements was estimated to be about 7400 km2, with 200 landslides classified. One of the largest landslides damaged Calitri village, in Avellino province. We have examined, as case histories, the reconstruction of Calitri and San Mango sul Calore villages, that were affected by severe landslides and were rebuilt in situ; we have also studied Conza della Campania that was reconstructed far from the original location. In the so-called Anthropocene age, the role of technical experts both in the built environment and in the social and ethical context is extremely important, for rebuilding the villages destroyed by earthquakes, especially in respect of the people resilience.

Results from a recent study on landslide distribution in the Republic of Macedonia have shown that the northwest part of the country is most prone to landsliding processes. In the past, there have been numerous landslides which have caused great damage to the infrastructure and endangered many villages. The last catastrophic event occurred on 3rd of August 2015 in the wider area of town Tetovo. The triggering factor for flooding and number of slope mass movements was heavy rainfall. The storms and floods were described as the worst to hit the area in over a decade. Relevant seismic events before and during the rainfall were not recorded. As a result of fast debris flow, 6 people lost their lives in Poroj village, while parts of it were covered by deep debris deposits. Roads and communal infrastructure in the entire region suffered of significant damages which caused problems in search and rescue operations. The study area Polog is located in the foothills of the Sar Mountain and divided by the river Pena. The broad area of the Municipality Tetovo itself has complex geological and tectonic conditions which also contributed to the degree of damage of the affected areas. Therefore, Tetovo and surrounding areas are vulnerable to both storm run-off and river flooding and consequently to different slope mass movements processes. In order to prevent such disasters in the future it is crucial to develop an integrated landslide risk management strategy. Efforts are made to prepare basic landslide susceptibility map of the region, which can serve as an integral part in the development of the strategy. Certain applications for risk management projects have been submitted by teams of domestic and international experts, which if approved can be of great value for the regional and local population and infrastructure.

The perspective of this study is based on the relationship between geomorphological and hydrogeological environments as natural support of the Sighisoara Citadel UNESCO heritage site and the impact of human activities on both of these. Since this system of the heritage site of the Sighisoara Citadel is composed of both natural and anthropogenic elements, the slope morphodynamic are controlled by their spatial distribution. The achievement of the main objectives of our study was possible using complex methodology: historical landslides mapping, geomorphological and geophysical methods, topographic and geotechnical survey and statistical analysis. Our results show that the geomorphological environment has changed dynamic features in the last decades. Also the hydrogeological conditions at shallow depth are different in the new context of higher values of human pressure generated especially by tourism phenomenon.

Involvement of local people in landslides disaster risk reduction planning, implementation and benefit sharing is the key to a participatory sustainable development approach at a local level. With this approach, Rolpa district which covers an area of 1879 km2 in the foot hills of Nepal Himalayas has been chosen as the study site. Almost 103 landslides were recorded through the participatory method, analyzed and compared with rainfall data and topographic features. Linear regression model showed that occurrence of landslides is increasing significantly over time but rainfall trend is decreasing gradually. Physical infrastructures and properties such as settlement areas, arable lands, roads, forests, spring (water sources) and irrigation canals were found to be damaged. More than 80% of the landslides affected settlements whereas only 20% affected irrigation canals. The ANOVA test showed that the size of landslide has insignificant (p > 0.05) effect on the number of places caused damage except in settlement areas. Moreover, slope failure due to steep relief is not significant rather larger sized and higher numbers of landslides occurred in gentle slope areas (slope ≤ 30°). Almost 80% of landslides occurred between elevations of 1200–2400 m a.s.l. with the majority in northern aspect. This study concluded that the causative factor of occurring of landslides is rain but occurrence further accelerated by anthropogenic activities either changing the topographic reliefs or application of improper conservation measures or both reasons. Major anthropogenic activities could be construction of roads, slope farming practices, houses constructed without due consideration of conservation measures in the recent decades. These results will be helpful to guide land use related planning related to soil and its productivity conservation, and water for the government, development agencies, stakeholders of Nepal, in general, and locals of Rolpa district, in particular to get the optimum benefits from those natural resources.

This session presents contributions describing landslides from highly contrasting climatic conditions ranging from boreal zone to mountains in temperate and tropical climate. Majority of the presented research is motivated by solving landslide problems with aim to prevent negative effects of landsliding on societies through improving knowledge about conditions and processes responsible for landslide occurrence and size. Large attention is paid to climate driven environmental processes (e.g. permafrost degradation) which increase landslide occurrence frequencies and magnitude.

During the last decade, the State of Veracruz (Mexico) experienced a series of intense rainfall seasons with more than 1000 registered landslides. As a consequence, more than 45,000 people had to be evacuated and resettled. Even though the mountainous areas of Veracruz are highly prone to landslides, neither susceptibility maps nor any other relevant information (distribution of landslides, geology, etc.) with high spatial resolution is available. The high social impact of the most recent landslide hazards points out the necessity of detailed investigations in the affected areas. The aim of this study is to improve the understanding of process dynamics for the landslides and to provide the base for future susceptibility mapping. As an example, a young landslide with a high complexity of nested processes from the year 2013 is selected for detailed investigations in the east Trans Mexican Volcanic Belt in the State of Veracruz, related to the complexity of the studied landslide a multi-methodological approach is applied, which includes geomorphological mapping, sediment characterization as well as geophysical methods (electrical resistivity tomography, seismic refraction tomography). Field results indicate that the studied landslide must be regarded as a reactivated older landslide body, with a variety of intricate processes and numerous secondary slides. Detailed investigations provide deep insights in the dynamics and interactions of landslide processes related to their natural and anthropogenic settings.

Understanding the formation and distinctive conditions that contribute to icing in cut slopes are needed to mitigate it for highway engineering. Using the K162 cut slope of the Bei’an-Heihe Expressway as a study site, we conducted field surveys, geological exploration, field monitoring, laboratory tests and numerical simulations to carry out an integrated study on the icing formation mechanisms and its influence on the slope stability. Research results show that: the surface unconsolidated Quaternary sediment and Tertiary sandstone provide passage for atmospheric precipitation infiltration; but underlying mudstone forms an aquiclude. Phreatic water forms in the loose overburden after infiltration. As the freezing front thickens, the phreatic aquifer thins and becomes pressurized. Slope cutting has exposed the phreatic aquifer. When the excess pore water pressure exceeds the strength of surface material, the pressurized water flows out of the slope, and freezes, forms icing. In the spring melt period, surface icing and shallow seasonal frozen soil melt completely, water infiltrates into the slope; but meltwater is blocked by the unfrozen soil in infiltrating process, accumulates on the interface between melted and frozen layers, increasing the water content at the mudstone interface. The mudstone reaches a saturated state, and its shear strength decreases, and forms a potential rupture surface.

Global climate change linked to meso-scale environment modifications such as regional above average precipitations, stronger El Niño-ENSO warm phase, global warming, permafrost degradation, and glacier retreatment could promote slope instability. However, which of these mechanisms is leading landslide activity in the high mountain landscape of Central Andes is still uncertain. Otherwise, changes of landslide features as consequence of these climate drivers is rare approached so proposal of effective preventive measures is not viable. The main concern of this research is to elucidate whether climate change is driving more frequent slope instability in the Central Andes. We focus on two key questions of our research: (1) Which landslide features are changing due to climate change? and (2) Which climate change mechanisms are certainly forcing landslides generation in the Central Andes? Our findings explain how the global environment change is shifting slope behavior in the Central Andes increasing landslide frequency and intensity, modifying landslide spatial distribution, shifting initial points of slope instability to higher topography, and generating more complex landslides. Main explanation for this shifting on slope instability behavior is intensified summer rainfall and global warming.

Chandmari Hill lies in Gangtok City in the Himalayan Mountain Ranges of Northeast India. The Himalayas are particularly prone to landslides due to complex geology combined with high tectonic activity, steep slopes, and heavy rainfall. Chandmari Hill has experienced a significant number of landslides, both rainfall and earthquake triggered, during the past several decades. Recently, the Government of India commissioned Amrita University to develop and deploy a landslide early warning system at Chandmari Hill. During the initial phase of the deployment, we conducted walkover surveys at Chandmari Locality, which comprises a large portion of Chandmari Hill. We also extracted and tested soil samples, drilled a 33.5 m borehole, and analyzed rock cores from the borehole. We present the results of laboratory soil tests and use these results in mathematical models. We examine all landslides (rainfall-triggered and earthquake-induced) recorded at Chandmari Locality during the past five decades. Simple calculations demonstrate that when the input parameters of the models mimic the field conditions precursory to an actual landslide, the factor of safety of the slope is less than unity. Gangtok City lies close to the Main Central Thrust, MCT2, which separates the gneissic rocks of the Paro/Lingtse Formation from the mica schists of the Daling Formation. Our field investigations revealed that at Chandmari Locality, gneissic rock overlies highly weathered mica schist. We postulate that surface runoff infiltrates through fractures in the overlying gneiss and results in an extrusion of the finer micaceous material, leading to subsidence which is routinely observed during the monsoon season. During torrential rains, rainwater infiltration causes the sliding of the soft micaceous bands underlying the gneissic rock, leading to rockslides at the hill. We suggest that similar processes are responsible for the frequent and widespread occurrences of landslides and subsidence observed throughout the region.

Study area in continuous permafrost zone, characterized by tabular ground ice distribution, is known for active slope processes. In 90-s main attention was paid to translational landslides (active layer detachments). Due to climate trends summer temperature became warmer, active layer depth increased. As a result, active-layer base ice thawed and stopped development of translational landslides. At the same time, tabular ground ice table got involved into seasonal thaw and triggered earth flows at the lake shores, the second known type of cryogenic landslides found previously mainly at the sea coasts. Earth flows are the main process in thermal denudation: a complex of processes responsible for formation of thermocirques. Thermocirques are semi-circle shaped depressions resulting from massive ground ice thaw and removal of detached material downslope. Monitoring of thermocirque activation and development allows analyzing climatic controls of thermal denudation, and rates of thermocirque enlargement. At present in the Yamal Peninsula tundra predominance of processes associated with tabular ground ice thaw (cryogenic earth flows) over the processes associated with the ice formation at the bottom of the active layer (cryogenic translational landslides) is observed. This is caused by deepening of the active layer and exposure of the massive ground ice (tabular ground ice or ice-wedges) within permafrost to first seasonal and then perennial thaw. Activation of thermal denudation which started on Yamal Peninsula in summer 2012, is associated with extremely warm spring and summer of this year, and the warmest July of 2013. By the end of the warm season thawing of the top of icy permafrost and tabular ground ice on some slopes resulted in cryogenic landsliding in the form of earth flows and further thermocirque development. Thermocirques may form on slopes of various aspects but develop faster on south-facing slopes.

In the northwest section of the Lesser Khingan Range located in the high-latitude permafrost region of northeast China, landslides occur frequently due to permafrost melting and atmospheric precipitation. High-density resistivity (HDR) and ground penetrating radar (GPR) methods are based on soil resistivity values and characteristics of radar-wave reflection, respectively. The combination of these methods together with geological drilling can be used to determine the stratigraphic distribution in this region, which will allow precise determination of the exact location of the sliding surface of the landslide. Field measurements show that the resistivity values and radar reflectivity characteristics of the soil in the landslide mass are largely different from the soil outside the landslide mass. The apparent resistivity values exhibit abrupt change at the position of the sliding surface in the landslide mass, and the apparent resistivity value decreased suddenly. In addition, the radar wave shows strong reflection at the position of the sliding surface where the amplitude of the radar wave exhibits a sudden increase. Drilling results indicate that at the location of the sliding surface of the landslide mass in the study area, the soil has high water content, which is entirely consistent with the GPR and HDR results. Thus, in practice, sudden changes in the apparent resistivity values and abnormal radar-wave reflection can be used as a basis for determining the locations of sliding surfaces of landslide masses in this region.

In boreal forests developed on permafrost, landslide processes are widespread, occur in years of above average summer-autumn precipitation and can cover up to 20% of total area of slopes adjacent to rivers. Permafrost landslides will escalate with climate change. These processes are the most destructive natural disturbance events resulting in complete disappearance of initial ecosystems (vegetation cover and soil). We have studied sites of landslides of different ages (occurred at 2009, 2001 and 1972) along with Nizhnyaya (Lower) Tunguska River and Kochechum River to analyze postsliding ecosystem changes. Just after the event (as at 1-year-old site in 2010), we registered drop in soil respiration, 3 times decreasing of microbial respiration contribution, 4 times lower mineral soil C and N content at bare soil (melkozem) middle location of a site. Results show that regeneration of soil respiration and eco-physiological status of microbial communities in soil during post disturbance succession starts with vegetation re-establishment and organic soil layer accumulation. As long as ecosystems regenerate (as at 35-year-old site), accumulated litter contains similar to control C and N content as well as the main pool of microorganisms, though microbial biomass and soil C and N content of old landslide area does not reach the value of these parameters in control plots. Therefore, forested ecosystems in permafrost area disturbed after landsliding requires decades for final successful restoration.

The present volume is devoted to landslides in various environments. Needless to remember here that landslide process is an extensive phenomenon able to affect the entire topographical context, from mountainous steep slopes to sub-horizontal area and that it is one of the major causes of disasters on earth.

Landslides are one of the most dangerous natural hazards in the world causing fatalities, destructive effects on properties, infrastructures, and environment. A correct evaluation of landslide risk is based on an accurate landslide susceptibility mapping that will affect urban planning, landuse planning, and infrastructure designs. Great effort has been devoted by the scientific community to develop landslide susceptibility models. Only few studies have been focused on defining accurate procedures for model selection, assessment, and inter-comparison. In this study we applied a methodology for objectively calibrate and compare different landslide susceptibility models in a framework based on three steps. The first step involves the automatic model parameter calibration based on different objective functions and the comparison of the models results in the ROC plane. The second step involves the intercomparison of a set of model performance indicators in order to exclude objective functions that provide the same information. Finally the third step involves a model parameter sensitivity analysis to understand how model parameter variations affect the model performances. In this study the three-step procedure was applied to compare two different simplified physically based landslide susceptibility models along the highway Salerno-Reggio Calabria in Italy. The model M2, able to consider the spatial variability of the soil depth respect to the model M1, coupled the distance to perfect classification index provided the most accurate result for the study area.

In hilly and mountainous regions, landslide dams can be recurring events involving river networks. A landslide dam can form when sliding material reaches the valley floor and closes a riverbed causing the formation of a water basin. Unstable landslide dams may collapse with catastrophic consequences in populated regions because of the resulting destructive flooding wave released. To prevent these consequences, the assessment of landslide dam evolution is a fundamental but not easy task, because of the complex interaction between watercourse and slope dynamics. Several researchers proposed geomorphological indexes to evaluate dam formation and stability for risk assessment purpose. These indexes are usually composed by two or more morphological parameters, characterizing the landslide (e.g. sliding material volume or velocity) and the river (e.g. catchment area or valley width). In this work, a procedure to evaluate landslide dam evolution is applied and reviewed. About 300 obstruction cases occurred in Italy were analyzed with two recently proposed indexes, the Morphological Obstruction Index (MOI) and the Hydromorphological Dam Stability Index (HDSI). The former, which combines the landslide volume and the river width, is used to identify the conditions that lead to the formation of a landslide dam or not. The latter, which combines the landslide volume and a simplified formulation of the stream power (composed by the upstream catchment area and the local slope), allows a near real time evaluation of the stability of a dam after its formation. The two indexes show a good forecasting effectiveness (61% for MOI and 34% for HDSI) and employ easily and quickly available input parameters that can be assessed on a distributed way even over large areas. The indexes can be combined in a convenient procedure to assess, through two subsequent steps, the final stage in which a landslide dam will evolve.

Despite the fact that landslide-dammed lakes represent less common lake type (n = 23; 2.6% share) in the Cordillera Blanca of Peru, these entities require appropriate scientific attention, because: (i) significantly influence geomorphological processes (erosion-accumulation interactions) at the catchment spatial scale; (ii) act as a natural water reservoirs and balance stream fluctuation on different temporal scales (daily to seasonal); (iii) may represent threat for society (lake outburst flood; LOF). The main objective of this study is to provide inventory of landslide-dammed lakes in the Cordillera Blanca, overview on their typology and discuss their geomorphological significance exemplified by two case studies. Existing, failed and infilled landslide-dammed lakes are simultaneously present in the area of interest. Three sub-types of existing landslide-dammed lakes are distinguished: (i) landslide/rockslide-dammed lakes situated in the main valleys; (ii) debris cone-dammed lakes situated in the main valleys; (iii) lakes situated on landslide bodies irrespective their location. Lakes of sub-types (i) and (ii) reach significant sizes, while lakes of sub-type (iii) do not. The dam formation of lake sub-types (i) and (iii) is usually connected with a single event, while the dams of sub-type (ii) are usually formed by several generations of debris deposition over time. It was shown, that landslide-dammed lakes in the study area are characterized by relatively low mean lake water level elevation (4115 m a.s.l.) and large catchments (in some cases up to 80 km2), compared to other lake types. Lakes of sub-type (ii) are predominantly situated in central glacierized part of the Cordillera Blanca, while lakes of sub-types (i) and (iii) are situated rather in the already deglaciated piedmont areas, reflecting the conditions and mechanisms of dam formation. Two illustrative examples are, further, studied in detail: rockslide-dammed Lake Purhuay close Huari in Marañon River catchment; debris cone-dammed Lake Jatuncocha in Santa Cruz valley, Santa River catchment.

Triggering factors for landslides could vary from heavy rainfalls/glacial activities to earthquakes, volcanisms or even vibrations due to nuclear explosions or heavy vehicle movement. However, in Sri Lanka landslides are mostly triggered due to heavy and prolonged rainfall. During last few decades, landslides have occurred with increasing frequency and intensity, causing extensive damage to lives and properties. Therefore, it becomes a necessity to predict and warn landslide hazards before it actually takes place which is still a mammoth task to achieve. Although several researches were done based on daily rainfall data in Sri Lanka, it has been identified that the extreme rainfalls with shorter durations could trigger more disastrous landslides. Hence, recommending hourly rainfall thresholds for landslides is much important in terms of hazard warning and preparedness. In this research an hourly rainfall trend was proposed in order to predict occurrences of landslides in Sri Lanka considering hourly rainfall data from twelve hours before to any disastrous event. Special attention was paid to data from Badulla District where more than 200 people were believed to be dead due to one major landslide in November 2014. The developed relationships are compared with Caine (1980) and observed to be matching to a considerable accuracy. Obtaining hourly rainfall data at exact location was almost impossible with the available rainfall measurement procedure in Sri Lanka. Much finer conclusions could have been made with more accurate data.

The Brahmaputra River has been the lifeline of north- eastern India since ages. This mighty trans-Himalayan trans-boundary river runs for 2880 kms through China, India and Bangladesh. The gradient of the Brahmaputra River varies from very steep near the source at the Tibetan plateau (1:385) to very flat in the lower part of Bangladesh (from 1:11,340 to 1:37,700). Geomorphologically, the Brahmaputra basin is very unstable as it is located in a high seismic zone. The Brahmaputra is a large alluvial river with highly variable channel morphology and a high degree of braidedness. The dominant flow is multichannel flow acknowledged to be very complex for mathematical modelling. The problems of flood, erosion and drainage congestion in the Brahmaputra basin are gigantic. The river bank failures are responsible for large scale bank erosion, aggradations and widening of the river channel. This in turn is responsible for lateral channel changes of the Brahmaputra River in many reaches leading to a considerable loss of good fertile land each year. Bank dynamics is also causing shifting of outfalls of its tributaries bringing newer areas under waters. Frequent changes of channel courses and bank erosion with high rate of siltation have also been identified as major threats to the riverine biota. This in turn has a negative impact on the sustainability of the wetlands. Degradation and destruction of the wetlands have considerable impact on the deteriorating flood hazard scenario in the state. This paper outlines the types of river bank failure mechanism and erosion process in the Brahmaputra River. The paper also presents information on the river reaches of Brahmaputra suffering from high bank erosion rates and the impacts of bank erosion on the Brahmaputra basin and people of the region.

On August 4, 2014, the failure of the Tailings Storage Facility dam at the Mount Polley copper and gold mine in British Columbia (Canada) produced a dynamic and complex geomorphic response downstream. The dam breach was caused by rotational sliding of the embankment due to foundation failure, resulting in sudden loss of containment of water and tailings. The released volume was estimated to be 25 Mm3. The resulting flow traveled approximately 9 km down the Hazeltine Creek valley over a vertical elevation of 205 m. The August 2014 event is the largest tailings dam failure recorded in Canada and the second largest recorded globally in the last decade. This investigation documents and analyzes the general downstream geomorphic response of the event in the Hazeltine Creek channel and floodplain. It utilizes an integrated approach of geomorphological mapping, topographic analysis, historical aerial photograph analysis, and field surveys to identify and quantify the geomorphic impacts of the event. Overall results indicate that these impacts are significant and comparable to those resulting from extreme debris flow and outburst flood events in mountainous environments in Canada and worldwide.

This study examined differences in landslide sediment production and sediment transportation abilities of reservoir watersheds in different geological environments after extreme rainfall. The watershed in this study covered an area of 109 km2; the upstream river banks of the reservoir contained interbedded shale and faulted shale and had a sandstone dip slope. This paper uses a LiDAR-derived DTM taken in 2005 and 2010 to investigate the landslide sediment production and riverbed erosion and deposition in the watershed. This study also applied the conservation of mass concept to analyze the sediment outflux in the subwatersheds. The research results indicated that although the right bank, which had interbedded shale and a sandstone dip slope, had a substantially greater number of landslides, the sediment production of it was less than that of the left bank, which had numerous deep-seated landslides caused by fault zones. However, affected by the higher sediment production of the left bank and under the same stream power, the left bank subwatersheds also had higher sediment outflux.

Spatially distributed physically based slope stability models are commonly used to assess landslide susceptibility of hillslope environments. Several of these models are able to account for vegetation related effects, such as evapotranspiration, interception and root cohesion, when assessing slope stability. However, particularly spatial information on the subsurface biomass or root systems is usually not represented as detailed as hydropedological and geomechanical parameters. Since roots are known to influence slope stability due to hydrological and mechanical effects, we consider a detailed spatial representation as important to elaborate slope stability by means of physically based models. STARWARS/PROBSTAB, developed by Van Beek (2002), is a spatially distributed and dynamic slope stability model that couples a hydrological (STARWARS) with a geomechanical component (PROBSTAB). The infinite slope-based model is able to integrate a variety of vegetation related parameters, such as evaporation, interception capacity and root cohesion. In this study, we test two different approaches to integrate root cohesion forces into STARWARS/PROBSTAB. Within the first approach, the spatial distribution of root cohesion is directly related to the spatial distribution of land use areas classified as forest. Thus, each pixel within the forest class is defined by a distinct species related root cohesion value where the potential maximum rooting depth is only dependent on the respective species. The second method represents a novel approach that approximates the rooting area based on the location of single tree stems. Maximum rooting distance from the stem, maximum depth and shape of the root system relate to both tree species and external influences such as relief or soil properties. The geometrical cone-shaped approximation of the root system is expected to represent more accurately the area where root cohesion forces are apparent. Possibilities, challenges and limitations of approximating species-related root systems in infinite slope models are discussed.

A few ancient landslides have been reported to be reactivated by the water level fluctuation in the Three Gorges Reservoir, China. On-site monitoring by Global Positioning System (GPS) is one of the most effective and accessible methods to understand the landslide deformation characteristic, which is the dominant factor for evaluating and predicting landslide stability. However, the monitoring points are usually limited and dispersed in landslides. A 3-D numerical simulation model was employed to study the spatial deformation of a landslide in the Three Gorges area, which was established according to its geological condition, and verified by comparisons of actual monitoring information and simulation recording data during a filling-drawdown cycle of the reservoir. The water level fluctuation has caused the landslide deformation, especially during the drawdown. The strong deformation zone exists in the forepart of the landslide, which lies mainly between 140.0 m and 200.0 m (EL.). The reservoir water variation controls the deformation of forepart near the river of the landslide. If the shear strength of slip surface reduces to c = 22.1 kPa, Φ = 8.7°, which is resulted by cyclic water filling-drawdown, the failure would occur and almost whole part of the landslide would be in plastic state.

The development of abrasion-landslide processes on the north-west coast of the Black Sea depends on several factors: geological structure, slope exposure, neotectonic, climatic and hydrodynamic conditions. However, the nature of this relation is not always obvious and insufficiently studied. The goal is to identify patterns of spatial and temporal development of landslide processes in the north-west coast of the Black Sea. Methods of correlation-regression, and spectral analysis were used. Periods of activation of landslide processes depending on changing climatic and hydrodynamic conditions were determined. On the south-west from the Odessa bay, abrasion process is described by dependence model abrasion indicators from wind wave energy, width of a beach and a precipitation. On the east from the Odessa bay the most proved model is dependence between abrasion indicators, sea level and a precipitation. Beaches have a significant role in the rate of abrasion and landslide processes. Gentle slopes at some sections of the beaches are the result of the predominance of silt and clay components in abraded loess strata of coastal slopes. All identified patterns have significant correlation coefficients (r > 0.5). It was found that the landslide processes in relation to climate and hydrodynamic impacts have a delay of 1–2 years, due to the inertia of the coastal geological system.

Slope stability reacts sensitively to changes of external factors including tectonic strain, temperature and precipitation regime, permafrost degradation, sea-level oscillations and land-use patterns.

We have compiled recently published and unpublished cosmogenic 10Be exposure ages of rock-avalanche deposits and break away scars in western and southern Norway in order to compare those to the retreat of the Scandinavian ice sheet. In total 22 rock-avalanche events were dated by their deposits (19) or break away scars (3). Sampling of rock-avalanche deposits and failure surfaces was not systematic over the region but with few exceptions we sampled all deposits within the same valley. All ages were recently calculated using the CRONUS online calculator and the geochronology ensemble reveal five late Pleistocene events, eight Preboreal events, and nine younger events. The decay of the Scandinavian ice sheet was not spatially synchronous but differed regionally and lasted over several thousand years in places, hence the requirement for widespread dating targets. One rock avalanche (at Innerdalen at 14.1 ka) occurred when ice existed in the valley, which is in agreement with the latest deglacial models. Depositional characteristics of ten (44%) of the rock avalanches suggest ice free conditions although they occurred within the first millennia following local deglaciation. Five events (22%) occurred between 9 and 7.5 ka at a time when climate was warmer and moister than today. Finally seven events (30%) appear to be relatively evenly distributed throughout the rest of the Holocene. Although limited in number we interpret that the dated events are representative of the temporal distribution of post-ice sheet rock avalanches in western Norway. However, the number of rock avalanches occurring onto the decaying ice sheet is likely underrepresented as those deposits are reworked and can be difficult to distinguish from moraine deposits. Our widespread data reveal a rapid rock slope instability response to the initial local decay of the Scandinavian ice sheet followed by a lower and constant frequency following the climate optimum (ca. 8.5 ka) in the Holocene.

Urbanization in hazardous regions, the abandonment of rural and mountain areas, and changed agricultural and forest practices have increased the impact of landslides through the years. Hence, the changing climate variables, like rainfall, acted and will act on a human-modified landscape. In this work, we analyze the role of rainfall variation and land use/cover change in the occurrence of landslides in Calabria in the period 1921–2010. Combining rainfall and landslide information, we reconstruct and analyze a catalogue of 1466 rainfall events with landslides (i.e., the occurrence of one or more landslide during or immediately after a rainfall event). To investigate the impact of land use/cover changes in the occurrence of landslides, we consider the “Land Use Map” made by the Italian National Research Council and the Italian Touring Club in 1956, and the “CORINE Land Cover” map released in 2000. Since our landslide catalogue is at municipality scale (i.e., for each landslide we known the municipality in which it occurred), we attribute a prevailing land use/cover class to each of the 409 municipalities of Calabria. We split the catalogue in two subsets (1921–1965 and 1966–2010) and correlate the landslides occurred in the first period to the 1956 land use and the landslides occurred in the second period to the 2000 land cover. We find that: (i) the geographical and the temporal distributions of rainfall-induced landslides have changed in the observation period; (ii) land use/cover in Calabria has changed between the two periods, with a huge decrease of arable land and an increase of heterogeneous agricultural areas and forests; (iii) in both periods, most of the landslides occurred in areas characterized by forests and arable land; (iv) in the second period, there was an increase (decrease) of landslides occurred in agricultural areas (arable land).

Within a project aimed at understanding past catastrophic rock slope failure in the Trentino Province of Italy, we studied the Castelpietra landslide. Castelpietra encompasses a main blocky deposit, with an area of 1.2 km2, which is buried on the upper side by more recent rockfall debris. The release area is the Cengio Rosso rock wall, which is comprised of Dolomia Principale and overlying Calcari Grigi Group dolomitized limestones. 36Cl exposure dates from two boulders in the main blocky deposit indicate that the landslide occurred at 1060 ± 270 AD (950 ± 270 yr ago). The close coincidence in time of the Castelpietra event with several events that lie within a maximum distance of 20 km, including Kas at Marroche di Dro, Prà da Lago and Varini (at Lavini di Marco) landslides, strongly suggests a seismic trigger. Based on historical seismicity compilations, we have identified the “Middle Adige Earthquake” at 1046 AD as the most likely candidate. Its epicenter lies right in the middle of the spatial distribution of the discussed landslides.

This paper presents coupled geomorphological processes such as glacial advances, gravitational collapses, and solifluction engaged to the environment climate changes. Complex landslides with a puzzling classification were identified by a landslide inventory of the Aconcagua Park involving the highest peak of South America (Aconcagua peak 6958 m a.s.l.). These deformed deposits were interpreted as gravitational collapsed moraines occurred after the Holocene–Pleistocene ice retreat on these Andean valleys. The stabilized huge masses began to be partially remobilized by solifluction phenomena generating protalus ramparts. At present well developed debris rock glaciers are established at the top landslide surfaces. This finding confirms glacial/interglacial cycles in the Central Andes are related to glacial advances supported by preserved moraines and gravitational collapses caused by ice loss during glacial retreat. However, the occurrence of cryogenic processes after collapse could evidence a periglacial environment restoration linked to a colder period. Therefore, available debris/sediments infilling deglaciated valleys will be mainly mobilized by glaciers, slope collapses or periglacial processes depending on the climate environment conditions.

This paper presents the influence of the marine erosion on slope stability in the south eastern coastal area of the Krk Island (north-eastern part of the Adriatic Sea). The bedrock (Paleogene marls and flysch) is occasionally covered with talus breccia from Quaternary period. The coast is strongly exposed to wave attack and thereby to marine erosion. Comparison of few orthophoto map generations shows significant coastal retreat during the fifty-year period. This phenomenon has been a fundamental trigger off different instability phenomena. The type of instabilities is a consequence of local geological fabric and resistivity of rock mass to marine erosion. In the investigated area, rock falls and slumps prevail in cliffs formed in talus breccias. Extremely high tides from 2008 and 2012 have caused significant coastal erosion. This is obviously an indicator of the possible higher hazard degree caused by the sea-level rise.

Rock avalanches can form complex deposits for which the interpretation can be challenging, especially if they occur in valleys affected by other ‘fast’ geological processes, such as, glaciations or isostatic rebound. The mountains of western Norway enable to study rock avalanches in such a complex geological setting. Within the two valleys of Innerdalen and Innfjorddalen (~70 km afar), several rock avalanches occurred since the Late Pleistocene. The rock avalanches in Innerdalen have volumes of 31 × 106 and 23 × 106 m3 and yielded terrestrial cosmogenic nuclide 10Be ages of 14.1 ± 0.4 and 7.97 ± 0.94 ka, while those in Innfjorddalen have volumes of 15.1 × 106, 5.4 × 106 and 0.3 × 106 m3 and yielded ages of 14.3 ± 1.4, 8.79 ± 0.92 ka and 1611–12 CE, respectively. Although being of nearly similar age, the rock avalanches in both valleys occurred under different environmental settings associated with the decay of the Scandinavian ice sheet. One of which fell onto a retreating valley glacier, partly depositing as supraglacial debris (Innerdalen), while the contemporaneous one fell into a fjord, partly forming a subaqueous deposit which is today exposed due to post-glacial isostatic uplift (Innfjorddalen). The younger rock avalanches fell into the ice-free valleys onto the older rock-avalanche deposits. All of the observed rock avalanches are preserved in rock-boulder deposits distributed on the valley floor and its slopes showing a variety of geomorphological features and landforms, which are diagnostic for their paleodynamics. Numerical runout modeling using DAN3D supports the landform interpretations, which are further confirmed by 10Be ages of the rock-avalanche deposits. The presented description of rock-avalanche deposits can enable a better identification and interpretation of similar deposits in other mountain areas and contributes to the knowledge of Quaternary landscape evolution in western Norway, such as, ice-sheet thickness and post-glacial isostatic rebound.

Human activities, including extensive land use practices, such as deforestation and intensive cultivation, may severely affect the landscape, and have caused important changes to the extent of natural forests during the last century in Southern Italy. Such changes had a strong influence on the frequency of occurrence of natural hazards, including landslides. Being one of the most significant control factors of slope movements, any variation in land cover pattern may determine changes in landslide distribution. The study area is the Rivo Basin which is located in Molise (Southern Apennines of Italy), a region severely affected by landslides. We prepared multi-temporal land cover and landslide inventory maps, aimed at developing different susceptibility maps to evaluate the effects of land cover changes in the predisposition to landslides. Based on the observed land cover trends in the study area, we simulated future scenarios of land cover in the attempt to assess potential future changes in landslide distribution and susceptibility. By investigating the relationship between the spatial pattern and distribution of past land cover settings and location factors (as elevation, slope, distance to settlements), we were able to calibrate a land cover change model to simulate future scenarios. The obtained results give important information both regarding the impact of past trends of land cover changes on landslide occurrence and possible future directions. They could be useful to provide insights toward a better land management for the study area, as well as for similar landslide-prone environments in Southern Italy, contributing to establish good practices for future landslide risk mitigation.

Study of post Last Glacial relief evolution in the southeastern part of Russian Altai (SE Altai) revealed that debris flows were widely presented in the region. After degradation of the last Pleistocene glaciation and drying giant ice-dammed lakes seismic excitation was one of the main factors that controlled intensification of slope activity. Geological and geomorphological researches of 2011–2015 in the Boguty river valley, SE Altai, were focused on studying geomorphic processes and reconstructing landscape evolution within the eastern periphery of the Chuya intermountain depression and Chikhachev range during the late Pleistocene-Holocene. Multidisciplinary approach, including determination of bio-composition of plant remnants from deposits of different genesis, tree species composition from charcoal fragments, micromorphological studies of surface and buried soils as well as litho-stratigraphic and pedogenetic analysis were applied for paleoclimatic and paleoenvironmental reconstructions. Geochronological investigations included radiocarbon dating of fossil soils, buried peats, lacustrine gyttjas and charcoal fragments. Within area of investigations seven sections were studied and 18 radiocarbon age estimations, covered time interval of the last 14 ka, were obtained. Obtained results indicate the tectonic origin of tributary valley of the Boguty river, which was settled along one of the faults in the late Pleistocene. Periods of tectonic quiescence and slope stability were repeatedly interrupted by periods of intensification of slope processes. Debris flows took place here about 7000, between 2800 and 1000, 650, 250 cal. years BP and could be triggered by both climatic and seismic events.

The bi-planar failure, sometimes referred to as “bi-linear failure”, is a particular type of rupture of rock slopes that occurs when a steep rock joint intersects a discontinuity having a lower inclination and that daylights at the rock face. The bi-planar configuration requires, differently from other well-known failure types (such as planar, wedge and circular failures), a considerable inner deformation and/or rock fracturing to make the block movement and the subsequent collapse possible. In the present paper, a forward analysis has been performed on a high natural rock slope (height = 150 m) made up of stratified limestone and characterised by a bi-planar sliding surface. The slope stability has been investigated adopting a 2D finite difference analysis (FDA). Two specific failure mechanisms (1 and 2) have been identified, based on the different strength parameters assumed in the models. In failure mechanism 1, a combination of internal shear and tensile fracturing occurs so as to form a deep, curvilinear rupture surface that links the two pre-existing planar surfaces. The block kinematism is an en-block roto-translation that, in turn, causes additional internal fracturing to accommodate deformation. In failure mechanism 2, a large shear band with obsequent dip enucleates within the unstable block, thus subdividing it into two main sub-blocks with different kinematisms. Model results demonstrate that bi-planar rock slope failures are associated with internal block damage that can also determine possible inner block splitting and differential movements between the secondary blocks. Stress-strain modelling is a very effective study approach that can be used to understand the key role played by rock fracturing and inner deformation occurring during the long preparatory phase that precedes the final collapse.

Slope instability is a major problem in hilly terrains. Stability assessment of road cut rock slopes is of paramount importance for planning and construction of infrastructures in hilly terrain. Slope Mass Rating (SMR) technique developed by Romana (1985) is a geomechanical method to assess the stability of rock slopes, that in principle uses basic Rock Mass Rating (Bieniawski 1979, 1989) and geometrical relationship between slope and rock discontinuities. In the present study, 39 rock slopes along Gopeswar-Almora road from Karnprayag to Narainbagarh in Chamoli district of Garhwal Himalayas have been studied in detail for their slope mass assessment using the mentioned technique. Based on the field observations, quartzite is the dominant lithotype with maximum of three sets of discontinuities in the study area. Meta Volcanic and Meta Sedimentary rocks are also present, but within narrow patches along the road, with phyllitic and schistose rocks. The parameters pertaining to Rock Mass Rating (RMR) and Slope Mass Rating (SMR) techniques were collected from field and laboratory studies for all the rock slopes. The basic RMR values of quarzitic rocks range between 50 and 88 whereas the SMR values vary from 07 to 84 depending upon the geometrical relationship between orientation of Slope face and discontinuities. For most of the schistose and phyllitic rocks basic RMR values are observed to be below 50 and the SMR values lie between 0 and 38. Based on the SMR values, these cut slopes were categorized into five different failure potential classes (Romana 1985). From the results, it is inferred that out of total 39 rock slopes, six slopes are completely unstable, 17 slopes are unstable, another six slopes are partially stable, nine slopes are stable, and only one slope is completely stable. From the kinematic analysis of slope face in relation to discontinuities, it was found that planar mode of failure is the most predominant type followed by wedge mode of failure in these rock slopes. Out of total slopes, 19 slopes are prone to planar failure, 8 slopes are prone to wedge failure, 3 slopes are more likely to fail by planar mode but has significant wedge failure component, 1 slope is prone to topple failure and 8 stable slopes.

Decentralized governance is critical to reducing disaster risks. This paper evaluates the decentralized landslide disaster risk governance in Uganda. Primary data were collected through household surveys and key informant interviews conducted in the landslide disaster prone Mount Elgon district of Bududa, Eastern Uganda. Secondary data were collected through document review. Primary and secondary data were analyzed using descriptive statistics and content analysis. The study findings reveal that in Uganda, landslide disaster risk reduction is perceived as a shared responsibility between different actors and involves wider stakeholder participation that has enhanced resource mobilization. Coordination of landslide disaster risk reduction has also been streamlined. Decentralized landslide disaster risk governance however, faces several challenges, including; financial and human resource constraints, political interference, corruption, uncooperative constituents and lack of an enabling sectoral law. Decentralized governance should therefore be upscaled to achieve landslide disaster risk reduction. Future research should focus on mapping key actors and institutions using Social Network Analysis to enable better resource allocation for landslide disaster risk reduction in the Country.

The availability of digital elevation model (DEM) delivered by airborne laser scanning (ALS) opens new horizons in the geomorphological research, especially in the landslide studies. This detailed geomorphological information allows for mapping of landslide affected areas using DEM data only. In order to map landslide areas in the automatic manner using machine learning classification algorithms and only DEM, generation of several DEM derivatives is needed. These first and second order derivatives provide information about specific properties of the terrain. However, involving a set of topographic features in the machine learning process increases significantly time of computations. Moreover, the topographic features are correlated since they are generated using the same DEM. The objective of this study is an in-depth exploration of the topographic information provided by the DEM data as well as the reduction of the computational time while the automatic landslide mapping. For this reason, a set of DEM derivatives have been generated and transformed into the principal component domain. The Principal Component Analysis (PCA) is a procedure that converts the set of correlated features into a set of linearly uncorrelated components using the orthogonal transformation. For the automatic landslide detection, the support vector machine (SVM) algorithm was used. The achieved results were compared with the existing landslide inventory map and overall accuracy and kappa coefficient were calculated. For the non-reduced original topographic model, we received 73% of overall accuracy. For the PCA-reduced models, accuracy parameters are not significantly worse. For instance, using only 7 principal components, which provide 90% of the total variability of the original topographic features, we received the overall accuracy of 72% while the computation time was reduced.

This Kamojang area is an Indonesian geothermal field that produces electricity since 1983. As many other geothermal fields in Indonesia, Kamojang area is located in high relief volcanic terrain where landslides frequently occur. Hydrothermal alteration of volcanic rocks is an important geological process which reduce slope stability due to the reduction of the rock mass strength properties. Landslides in a geothermal area are hazards that can adversely affect roads, pipelines, as well as injection and geothermal wells. The aim of this study is to enhance the understanding of landslide processes in highly weathered and hydrothermal altered volcanic rock masses based on field, laboratory and numerical modelling studies. Exemplarily for this geological situation, the study site of the geothermal area of Kamojang in Indonesia was chosen. This article presents an overview of the study area and some preliminary results from a data compilation study and a field survey during this summer.

A forecasting algorithm using Support Vector Regression (SVR) used to forecast potential landslides in Munnar region of Western Ghats, India (10.0892 N, 77.0597 E) is presented in this paper. Forecasting for the possibility of landslide is accomplished by forecasting the pore-water pressure (PWP) 24 h ahead of time, at different locations and across soil layers under the ground at varying depths, and computing Factor of Safety (FoS) of the slope. It is done by learning from the real-time sensor data gathered from Amrita University’s Wireless Sensor Network (WSN) system deployed in Western Ghats for monitoring and early warning of landslides. We use two variations of SVR, SVR-Historic and SVR-Adaptive. SVR-Historic algorithm is trained with the data from July 2011 to December 2015 and tested for the period from January to November 2016. SVR-Adaptive algorithm is adaptively trained from July-2011 onwards and tested for the period from January to November 2016. PWP and the computed FoS from both the algorithms are compared with the actual PWP and FoS data and the Mean Square Error (MSE) for the SVR-Historic model is found to be 48.726 and 0.002 whereas the MSE for SVR-Adaptive model is found to be 12.438 and 0.0007 respectively. The PWP and the computed FoS from both the algorithms are tested for correlation using Pearson’s correlation test, with 95% confidence interval and the coefficients for PWP is found to be 0.804 and 0.959 respectively with p-value of 2.2e−16, whereas for FoS it is 0.802 and 0.955 with p-value of 2.2e−16. The confidence intervals for PWP and FoS from both the models is 0.763 to 0.839 and 0.950 to 0.969 respectively. Among the two forecasting models, SVR-Adaptive model performs better with a low MSE of 12.438 and 0.0007 in forecasting PWP and the computed FoS values respectively and correlates with the real-time data ~95% of the times. Application of this forecasting algorithm in real-world can thus provide 24 h extra time for early warning which is a boon for government and public to prepare for landslides after early warnings.

The collapse and consequent spreading of a column of granular or cohesive material is a simple experiment used by many research groups to study the rheology of the soils and for calibrating numerical propagation models. This paper deals with the results of a comprehensive experimental program carried out with mixtures of sand, kaolin and water: the main aim of the program is to know and understand how the mixture composition influences the collapse and run-out mechanism. In particular, the run-out length and the profile of the final deposit are the two fundamental characteristics taken into consideration to distinguish each test and to find a relation with the mixture composition. Four percentages of kaolin and water are considered for the experiments and different amounts of sand are added to these matrices. The main aim is the comprehension of the role of the coarser granular material in a cohesive collapsing mass. Finally, the dependency of the final runout on the aspect ratio of the initial column is discussed.

Flexible barriers have received increasing attention in debris flow control because they are more economical and easier to install when compared with rigid barriers. However, in the design of a flexible barrier, the debris impact force is difficult to estimate, even if sophisticated numerical analysis is employed. In this paper, suggestions for simplified impact force estimations are given. At first, the existing approaches to estimate the impact force for impermeable rigid barriers are modified to cater for the case of a flexible barrier. We consider that there are two key characteristics of flexible barriers when compared with rigid barriers: flexibility and permeability. Flexibility exemplifies itself in a longer duration of impact. A simple spring-mass system is used to represent the interaction of the debris flow and barrier and observed impact times are considered. It is deduced that the impact force on a flexible barrier should be less than half of that for a rigid barrier, both being impacted by the same/similar debris flow. Furthermore, for a ring net which is impacted by a debris flow of substantial mass and velocity, it is considered that the impact load is proportional to the elastic deformation of the flexible barrier in the direction of flow. Impact force calculated using the preceding assertion has been compared with the impact force in published results, and a satisfactory comparison is found. Large-scale experiments are proposed so that the validity of the above assertions can be ascertained. Permeability, the other key characteristic of a flexible barrier, can also influence the impact force as less force will be imposed on the barrier if less debris mass is retained by the barrier. Large-scale experiments are also proposed to investigate the relationship between the barrier net opening size and the debris impact force. Besides, existing approaches for estimating debris flow loading on impermeable rigid barriers are reviewed and improved by introducing a drag force which can impede the impact force. Then the largest force combination during the impact process cannot be simply determined as the largest dynamic loading or the largest earth pressure loading, and it can only be decided by calculating the largest force of all three stages.

To design technical mitigation structure against debris flows in torrents it is important to define realistic design impact loads. Presented impact forces were mostly derived from back calculations of past events and yielded a rough estimation. The majority of scientific publications of impact force are based on small scale experiments in laboratories, but the transfer to real scale problems is limited due to scaling issues. Monitoring in real scale of debris flows is necessary to understand the process and the apparent phenomena. The Gadria valley in the Autonomous Province of Bozen-Bolzano is one of the rare areas were debris flows frequently occur. Therefore the Gadria torrent is already equipped with a monitoring station to provide data to analyze the occurring debris flows. To measure real scale impact forces of a debris flow and the variables that are necessary to calculate and understand the impact process and the debris flow/structure/ground interaction, a special monitoring check dam is designed and will be built in September 2016. An arrangement of 38 sensors will measure the impact forces on the check dam, the acceleration of the construction and the interaction with the ground. Also the pore water pressures, weights and heights of the debris flows will be recorded. This arrangement of sensors should help to understand the debris flow structure interaction to facilitate the calibration of numerical models and to improve guidelines for national standards.

The deep large-scale landslide near Aratozawa Dam in Miyagi Prefecture of Japan was occurred in 2008 and still the initiation mechanism and motion behavior were not explained in detail up to now. This paper aims to report briefly the detail study of the Aratozawa landslide. We conducted several experiments to test the Aratozawa samples using the newest version of the undrained dynamic loading ring shear apparatus. As reported by Sassa et al. (2014), the ring shear apparatus was designed with the single central axis-based for the normal stress loading system, with the normal stress and pore pressure measurement capacities of up to 3.0 MPa. The friction coefficient, shear displacement at the start and end of shear strength reduction, mobilized friction angle and steady state shear resistance of the Aratozawa samples were obtained from the ring shear tests. Experiments results implied that the shear strength reduction in progress of shear displacement of the Aratozawa samples was caused not only by the earthquake but also by factor of the initial pore pressure (Setiawan et al. 2014, 2016). Further analysis has been conducted by occupying shear parameters of soil failure resulted from experiment as a critical inputs for the LS-RAPID geotechnical simulation. LS-RAPID landslide simulation model is used to observe the overall process of landslide phenomena started from initiation to moving process. The Aratozawa landslide was successfully simulated using LS-RAPID model which involves the pore pressure increase, seismic loading, and landslide volume enlargement during traveling process. However, factor of the reservoir and its relation to the groundwater and bedrock is still needed to analyze in further.

The aim of this paper was identification of rock fall prone areas above the historical town of Omiš, located at the Adriatic coast in Croatia. Unstable areas were identified by kinematic analysis performed based on relative orientations of discontinuities and slope face. Input data was extracted from the surface model created from the high-resolution point cloud. The town of Omiš is threatened by rock falls, because of its specific location just at the toe of Mt. Omiška Dinara. Rock fall risk is even higher due to rich cultural and historical heritage of the town. Collection of spatial data was performed by Time of Flight and phase-shift terrestrial laser scanners in order to derivate high resolution point cloud necessary for derivation of surface model. Split-FX software was used to extract discontinuity surfaces were semi-automatically from the point cloud data. Spatial kinematic analysis was performed for each triangle of TIN surface model of the investigated slopes to identify locations of possible instability mechanism. From the results of the spatial kinematic analysis, the most critical parts of the slope have identified for planar and wedge failure and flexural and block toppling. Verification of identified rock fall areas was performed by visual inspection of hazardous blocks at the surface model. Identified rock fall prone areas, unstable blocks and probable instability mechanisms on the steep slopes above the town Omiš, present the input data for risk reduction by efficient design of countermeasures.

The automatic detection of sediment related disasters like landslides, debris flows and debris floods, gets increasing importance for hazard mitigation and early warning. Past studies showed that such processes induce characteristic seismic signals and acoustic signals in the infrasonic spectrum which can be used for event detection. So already many studies has been done on signal processing and detection methods based on seismic or infrasound sensors. But up to date no system has been developed which uses a combination of both technologies for an automatic detection of debris flows, debris floods or landslides. This work aims to develop a system which is based on one infrasound and one seismic sensor to detect sediment related processes with high accuracy in real time directly at the sensor site. The developed system compose of one geophone, one infrasound sensor and a microcontroller where a specially developed detection algorithm is executed. Further work tries to get out more information of the seismic and infrasound signals to enable an automatic identification of the process type and the magnitude of an event. Currently the system is installed on several test sites in Austria, Switzerland and Italy and these tests show promising results.

The Akatani landslide triggered by heavy rainfall during Typhoon Talas on 4 September 2011 is one of 72 deep-seated catastrophic rock avalanches in Kii Peninsula, Japan. The landslide is about 900 m in length, 350 m in average width and 66.5 m of maximum depth of the sliding surface. A rapid movement of the landslide was downward the opposite valley and formed a natural reservoir that has a height of about 80 m and a volume of 10.2 million m3. This paper presents preliminary results of the simulation of the formation process of the Akatani landslide dam by using ring shear apparatus incorporated with a computer simulation model LS-Rapid. Ring shear tests on sandstone-rich materials and mudstone-rich materials taken near the sliding surface indicated that a rapid landslide was triggered due to excess pore water pressure generation under shear displacement control tests and pore water pressure control tests. The pore water pressure ratio (r_u) due to rainfall was monitored from 0.33 to 0.37 in the ring shear tests on rainfall-induced landslides, approximately. Particularly, the formation process of the Akatani landslide dam and its rapid movement were well simulated by the computer model with physical soil parameters obtained from ring shear experiments. The actual ratio of pore water pressure triggering landslides was 0.35 in the computer simulation model. The results of the Akatani landslide simulation would be helpful to the understanding of failure process of deep-seated landslide induced by rainfall for future disaster mitigation and preparation in the area.

Numerous landslides of different types present common hazardous phenomena in the Vinodol Valley (64.57 km2), situated near the City of Rijeka in coastal part of Croatia. During the previous and present geological investigations in the Vinodol Valley almost all landslide types were identified: falls, topples, slides and flows. The Vinodol Valley is characterized by irregular shape and a range of different landforms due to complex geological and geomorphological conditions. The inside of the valley is built of Paleogene siliciclastic (flysch) deposits, which is surrounded by the relatively steep carbonate borders composed of Upper and Cretaceous limestone. Along the most part of the NE border vertical rocky cliffs occur. The lower parts and the bottom of the valley (i.e., flysch deposits) are covered by heterogeneous Quaternary superficial deposits. In the Vinodol Valley more than 200 active and dormant landslides in soils were identified. Most of the active landslides are covered by dense forest vegetation. Original landslide topographies of dormant landslides are significantly modified by the anthropogenic agricultural activities. For this reason, the appropriate landslide identification and mapping method is the visual interpretation of the high-resolution LiDAR-derived imagery. Identified landslides are generally shallow to moderate shallow, with slip surface depth of several meters, and small to moderate small, with volumes in a range of 103–105 m3. Due to the diversity of geological conditions in the Vinodol Valley and the large number of identified landslides, the index and classification properties of soils from the landslide-forming materials were investigated. Soil samples were taken and laboratory tested according to the rules of the European Soil Classification System. In this paper, results of preliminary investigations of the relationship between the different types of landslides and the landslide-forming materials are presented.

Rainfall-induced landslide might transformed into more severe disaster, namely debris flow and natural dam which both holds serious threats on human life and material. The runout distance has crucial role for determining affected areas of a landslide. Our previous research found the correlation of inflow angle and stream gradient to transformation of landslide collapsed sediment either into natural dam or debris flow. This research intended to test our previous research result with a small flume experiment and aimed to analyze the influence of sediment inflow angle and stream gradient to the sediment deposition percentages as representative of runout distance and the possibility of natural dam formation. Soil samples were taken from landslide-triggered debris flow disaster initiation zone in Hiroshima (Hiroshima Pref.) and Izu Oshima (Tokyo Pref.), Japan which were induced by heavy rainfall. The small flume was 10 cm width and 15 cm height, the inflow segment angle was varied to 60° and 90°, and the stream segment gradient was varied to 10° and 15°. From the experiment results, stream gradient influence the sediment movement effectively rather than inflow angle, and it was sufficient to examine the possibility of collapsed sediment to form natural dam or debris flow. Soil samples from natural dam initiation zones and consideration of water content factor are essential for further experiment.

This paper represents a relative landslide risk assessment of the City of Valjevo in Western Serbia. After the extreme rainfall during the May 2014, many new landslides were triggered, and Valjevo was one of the most affected areas in Serbia. The modeling was preceded by the data selection, and included ranging and preprocessing of the conditioning factors. The following eight factors were chosen as representative: stream distance, slope, lithology, elevation, distance from hydrogeological borders, land use, erodibility and aspect. Landslide susceptibility analysis was completed using the Analytical Hierarchy Process (AHP) multi-criteria method. Validation was performed by cross-referencing with an existing landslide inventory, which was made by field mapping and interpretation of satellite images. Finally, the relative risk was determined for the City of Valjevo by using a realistic population distribution model as a source for elements at risk. The results show the distribution of risk and suggest that 20% of the inhabited area falls into the high risk class, but this encompasses less than 5% of the total population.

The study area is located along the Andean active orogenic front comprising the most seismically active region of Argentina. Main Quaternary deformation is concentrated in this Western central part of the country associated with active faults linked to an intense shallow seismic activity (<35 km depth). During the last 150 years, the region has suffered at least six major earthquakes with a magnitude greater than Ms ≥ 7.0. The focus of this research is to analyse the landslide behaviour along this Andean active orogenic front. To that end, we carried out a landslide inventory along Precordillera (31°–33°S). We analysed type, size, activity grade and other morphological parameters of these landslides. We found huge collapses coincide with traces of active Quaternary faults in this region. However, landslides are clustered being denser splayed in the centre of study area. Furthermore, activity grade of such landslides is higher in this central zone decreasing gradually towards the north and the south. This central area is affected by the Juan Fernandez Ridge which is likely related to higher deformation rate.