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Large slope collapses have been known to trigger extreme rushes of air loaded with projectiles (airblasts) capable of causing destruction and fatalities far beyond run-out of the rock mass. An appraisal of the likelihood of a destructive airblast should be a component of landslide risk assessments. Yet there is an absence of risk studies directly examining landslide-related airblasts. In this work we back-analyze an unreported airblast in the Sikkim Himalayas (India) and several other airblasts documented around the world. We explore the conditions a large slope collapse should meet to trigger a significant airblast, and we establish a semi-empirical relationship linking the potential energy in a collapse with airborne trajectory and the extent of the related airblast. The collapse of thousands or millions of cubic meters falling from a significant height results in a sudden release of energy (1011J to 1013J) and a high degree of comminution of rocks, causing a violent displacement of air. Average wind speeds of airblasts following impacts with airborne trajectory can be double the speed of rock avalanches. The size of the damage zone depends on the potential energy of the falling rock mass and can be amplified or reduced depending on how confined the valley is where the airblast occurs.

Rock avalanche clusters can be relevant indicators of the evolution of specific regions. They can be used to define: the type and intensity of triggering events, their recurrence and potential probability of occurrence, the progressive damage of the rock mass, the mechanisms of transport and deposition, as well as the environmental conditions at the time of occurrence. This paper tackles these subjects by analyzing two main clusters of rock avalanches (each event between 0.6 and 30 Mm 3 ), separated by few kilometers and located along the coastal scarp of Northern Chile, south of Iquique. It lies, hence, within a seismic area characterized by a long seismic gap that ended on April 1st, 2014 with a M w 8.2 earthquake. The scar position, high along the coastal cliff, supports seismic triggering for these clusters. The deposits' relative positions are used to obtain the sequence of rock avalanching events for each cluster. The progressive decrease of volume in the sequence of rock avalanches forming each cluster fits well the theoretical models for successive slope failures. These sequences seem to agree with those derived by dating the deposits with ages spanning between 4 kyr and 60 kyr. An average uplift rate of 0.2 mm/yr in the last 40 kyr is estimated for the coastal plain giving a further constraint to the rock avalanche deposition considering the absence of reworking of the deposits. Volume estimates and datings allow the estimation of an erosion rate contribution of about 0.098–0.112 mm km − 2 yr − 1 which is well comparable to values presented in the literature for earthquake induced landslides. We have carried out numerical modeling in order to analyze the mobility of the rock avalanches and examine the environmental conditions that controlled the runout. In doing so, we have considered the sequence of individual rock avalanches within the specific clusters, thus including in the models the confining effect caused by the presence of previous deposits. Bingham rheology was the most successful at explaining both the distance and the geometry of the observed events.

InSAR Norway, a public national ground motion service, based on Copernicus Sentinel-1 data, was launched in November 2018. The service provides regularly updated ground motion time series on over two billion locations in Norway. The service provides this data freely and openly to all interested users, through a web browser interface. Within the government, this data in instrumental for landslide hazard and risk assessment as well as monitoring. Other applications include evaluation of urban subsidence and infrastructure monitoring. Many scientific applications also benefit, such as in the fields of geomorphology and geodesy.InSAR Norway is operated by the Geological Survey of Norway, with cofunding from the Norwegian Space Centre and the Norwegian Water and Energy Directorate. Processing is done on a high-performance computing cluster (HPCC) using software developed by the KSAT-GMS partnership (NORCE – formerly NORUT, PPO.labs and Kongsberg Satellite Services).

World Landslide Forum (4º. 2017. Liubliana, Eslovenia), Exposure to hazards is expected to increase in Europe, due to rapid population growth in urban areas and the escalation of urbanization throughout many countries. In the framework of the European Geological Surveys (EGS), the Earth Observation and Geohazards Expert Group (EOEG) has carried out a survey based enquiry regarding the integration of geohazards (earthquakes, volcanoes, landslides, ground subsidence, floods and others) into urban and land-use planning. Responses from 19 European countries and 5 regions reveal heterogeneous policies across national borders. 17% of the countries have not yet implemented any legal measures to integrate geohazards into urban and land-use plans and half of the participating countries have no official methodological guides to construct geohazard maps. Additionally, there is a scarce knowledge about real social impacts of geohazards and resulting disasters in many of the countries, although they have a significant impact on their national economies. This overview stresses the need for a common legislative framework and homogenization of the national legislations as well as mutual guidelines which adopt the principles applicable to the management of geohazards and explain the process to be followed in the production of hazard documentation. This is especially relevant in case of landslide and subsidence hazards; although those are of great importance in Europe, there are no common guidelines and practices similar to Directive 2007/60/EC on the assessment and management of flood risk. Based on their expertise, EuroGeoSurveys (EGS) have the potential to coordinate this activity in European geohazard guidelines and to promote the interaction among stakeholders., Geohazards InSAR Laboratory and Modeling Group, Instituto Geológico y Minero de España, España, Bureau de Recherches Géologiques et Minières, Francia, Engineering Geology Department, Institute of Geology and Mineral Exploration, Grecia, GeoHazard team, Geological Institute of Romania, Rumanía, Geological Survey of Slovenia, Eslovenia, Croatian Geological Survey, Croacia, Geological Survey of Italy, Italia, Swiss Federal Office for the Environment, Suiza, Geological Survey of Austria, Austria, Polish Geological Institute, National Research Institute, Polonia, Geological Survey of Ireland, Irlanda, Czech Geological Survey, República Checa, Federal Institute for Geosciences and Natural Resources, Alemania, Geological Survey of Norway, Noruega, Cyprus Geological Survey, Chipre, Geological Survey of Sweden, Suecia, Institut Cartogràfic i Geològic de Catalunya, España, British Geological Survey, Reino Unido, Geological Survey of Slovakia, Eslovaquia, Geological Survey of Lithuania, Lituania, Federalni Zavod Za Geologiju, Nigeria, Geological Survey of Estonia, Estonia, Laboratorio Nacional de Energia e Minas, Portugal, Geological Survey of the Republic of Srpska, Bosnia y Herzegovina

Catastrophic rock avalanches contribute to rapid landscape evolution and can harm humans directly or by secondary effects such as displacement waves. Predicting the volume, timing, and consequences of rock slope failures is therefore essential to managing risk and interpreting landscape response to climatic or tectonic forcing. Here, we synthesize geologic and geodetic observations to document the spatial pattern of movement rates and failure mechanisms at a landslide complex in western Norway, recently identified with systematic interferometric synthetic aperture radar (InSAR) reconnaissance. A differential global navigation satellite system (dGNSS) and global positioning system (dGPS) campaign confirms active slope deformation with horizontal displacement rates of 1.2 to 2.6 mm year−1 at four points distributed across the landslide’s ~1.8-km width. Displacement vectors are consistent with landslide movement occurring on pre-existing discontinuity sets, and a broad synform controls failure mechanisms within the landslide complex. Two ~1.5 million m3 blocks are wedge failures, while flexural toppling and planar sliding of smaller blocks occur throughout the landslide complex. Modern movement rates are comparable to or slower than Holocene-averaged displacement rates, suggesting continued steady deformation or stabilization of parts of the landslide with time. However, a large volume failure with typical run-out for rock avalanches would likely reach the subjacent fjord, causing a displacement wave. We suggest that our collaborative approach of integrating a wide variety of geologic and geodetic methods will be useful for more thoroughly documenting additional landslide sites and for making informed decisions about risk management.

Rockslides have a high socioeconomic and environmental importance in many countries. Norway is particularly susceptible to large rockslides due to its many fjords and steep mountains. One of the most dangerous hazards related with rock slope failures are tsunamis that can lead to large loss of life. It is therefore very important to systematically identify potential unstable rock slopes. Traditional landslide monitoring techniques are expensive and time consuming. Differential satellite interferometric synthetic aperture radar (InSAR) is an invaluable tool for land displacement monitoring. Improved access to time series of satellite data has led to the development of several innovative multitemporal algorithms. Small baseline (SB) methods are based on combining and inverting a set of unwrapped interferograms that are computed with a small perpendicular baseline in order to reduce spatial phase decorrelation. Another well proven technique is the persistent scatterer interferometric method (PSI) that is based on analysis of persistent point targets. In this paper, we apply both approaches to study several rockslide sites in Troms County in the far north of Norway. Moreover, we take the opportunity to address the difference and similarities between the SB and the PSI multitemporal InSAR methods for displacement studies in rural terrain.

Structural, geomorphic, and interferometric synthetic aperture radar (InSAR) surface displacement data show that uplift of the northernmost onshore Scandinavian passive margin is associated with active normal faulting and anomalous clusters of landslides. Regional-scale normal faults separate alpine footwall ranges with impressive range-front scarps from more gentle hanging-wall topography. In the Lyngen region, rockslides, sackung features (i.e., deep-seated slope gravitational deformation), and active faults cluster inside an ~1000 km 2 area of hanging-wall subsidence parallel to an ~30-km-long, faceted range-front scarp. From postglacial to recent time, rockslides have been released along the main range front and other propagating scarps, both in the footwall range and in structurally controlled, glacially oversteepened valleys of the hanging wall. The active rockslides, moving at rates of >10 mm/yr, show a variety of relationships to the controlling structures, reflecting tectonic as well as gravitational faulting. Recent and present-day landscape evolution and large-volume rockslide distribution in Scandinavia should be viewed from the perspective of tectonic processes involving active normal faults.

Satellite and ground-based interferometric radars have the potential to measure the displacement of active rockslides. Data describing the spatial- and temporal displacement patterns of a rockslide are essential contributions to the total understanding of a rockslide. A better overview of the kinematics will in turn improve the quality of a risk assessment. In this study we have processed TerraSAR-X satellite data, collected since 2009, from both ascending and descending satellite tracks together with ground-based interferometric radar observations of an active rockslide in Northern Norway. Findings show that both the satellite and the ground-based data delimit the active rockslide area and that the displacement rates are highest in the upper part of the rockslide. In the lower parts of the rockslide, the displacement pattern shows a possible compressional toe-zone together with a fast moving lobate shaped landform.