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Urban avalanche search and rescue operations in Longyearbyen: A study of public-private cooperation
Published in Stein Haugen, Anne Barros, Coen van Gulijk, Trond Kongsvik, Jan Erik Vinnem, Safety and Reliability – Safe Societies in a Changing World, 2018
It is quite common to distinguish between two main types of avalanches; loose snow avalanches and slab avalanches. A loose snow avalanche is a chain reaction initiated at a specific point, and expands both in width and depth as it continues downwards (Landrø 2007). The initiating point in a loose snow avalanche consists of a small layer of surface snow that loosens, while it is a thin and weak layer of snow at a deeper level that fails in a slab avalanche. A slab avalanche is further characterized by a large and coherent mass of snow that loosens and splits into blocks as it moves downwards (McClung and Schaerer 2006). This type of avalanche reaches high speed in a short period of time, and the width can be several hundred meters, within seconds (Landrø 2007). A loose snow avalanche has a pear shaped pattern, while a slab avalanche usually has a rectangular shape (McClung and Schaerer 2006). 99 per cent of the avalanche accidents occur due to slab avalanches (Landrø 2007). The 2015 and 2017 urban avalanches in Longyearbyen were slab avalanches.
Introduction
Published in Yasmina Bestaoui Sebbane, Intelligent Autonomy of Uavs, 2018
Mountain risks Snow avalanches are an inherent consequence of the dynamic and variable snow cover in steep mountainous terrain. Even though avalanches are rare natural hazards, they cause the majority of winter fatalities as well as significant infrastructure loss worldwide. Thus, avalanche research is risk research, dealing with risk reduction by trying to understand avalanche formation in space and time, relative to meteorological and snow pack triggering factors. Traditionally, field-testing of snow properties, field reconnaissance of avalanche activity and dynamics, and modeling of both are used to study avalanche formation. Remote sensing enables objective, safe, and spatial continuous observations of snow avalanches at different spatial scales. Today’s abundance of sensor platforms and their sensitivity to a broad range of wavelengths allows for detection of avalanches and associated snow-pack processes. UAV is one of them [38]. Search for victims is resource intensive and time consuming to do if the avalanche spans a large geographical area in rough terrain. Survival decreases rapidly with time to extrication. More than half of avalanche victims are partially buried and visible on the surface. The objective in [14] was to evaluate feasibility of using a rotor-craft UAV to support situation assessment in search and rescue operations in the mountains.
Landslide risk management in Norway
Published in Ken Ho, Suzanne Lacasse, Luciano Picarelli, Slope Safety Preparedness for Impact of Climate Change, 2017
B. Kalsnes, F. Nadim, R.L. Hermanns, H.O. Hygen, G. Petkovic, B.K. Dolva, H. Berg, D.O. Høgvold
In the changing climate, the landslide types most likely to increase in frequency are “wet” landslide types, such as debris flow and slush avalanches. These landslide types are usually not taken into account for when planning new roads. “Wet” avalanches are often triggered by human activity in the release area. Prevention methods are drainage, open or closed control dams and/or bridges in avalanche course, deflectors, sedimentation basins, alternative drainage paths in the runout area, and moving the road. Alternative drainage paths are an important remedial measure for sediment transport along streams and rivers, for ensuring operative drainage systems. A risk assessment of existing roads with respect to increased erosion and sediment transport should be carried out. One of the conclusions from the programme was that more effort should be put into operation of drainage systems than is done today.
Acoustic emission monitoring and analyses for avalanche release and slab fracturing events observed in Great Himalaya
Published in Nondestructive Testing and Evaluation, 2023
J C Kapil, Sakshi Sharma, Karmjeet Singh, J S Shahi, Rama Arora
AE activities with abrupt increase were identified during the periods of avalanche release and slab fracturing events. The abrupt increase in the AE parameters with progressively increasing trends of βin were observed nearly 13 hours prior to avalanche release, which is attributed to the evolution of the instability within the snowpack. In our exploration of avalanche release case, the failure activity was started presumably within a persistent weak layer formed below a cohesive slab under the excessive loading by continuous accumulation of new snow. In this case, crack propagation occurred after the critical strength is exceeded which resulted into avalanche release. The progressively increasing βin-values were likely related to the ongoing damage process in snow under the excessive loading, and a sharp increase in the βin-values prior to avalanche release can be considered as an indicator for the onset of critical instability. The associated snowpack profiles, stability information, prevailing snow-meteorological parameters along with the images for avalanche release and fractures on snow surface have also supported this investigation.