Assessment of data availability for the development of landslide fatality curves

Abstract

Quick clay landslides are a special feature of Norwegian and Swedish geologies. Vibrations or small initial landslides can cause a quick clay layer to collapse and liquefy, resulting in rapid landslides with little or no time for evacuation, making them a real threat to human life. Research concentrating on damages due to landslides is scarce, and analyses of loss of human lives caused by quick clay landslides in the scientific literature are, to our knowledge, non-existing. Fatality quantification can complement landslide risk assessments and serves as guidance for policy choices when evaluating efficient risk-reducing measures. The objectives of this study were to assess and analyze available damage information in an existing data set of 66 historical landslide events that occurred in Norway and Sweden between 1848 and 2009, and access its applicability for quantifying loss of human life caused by quick clay landslides. Fatality curves were estimated as functions of the number of exposed persons per landslide. Monte Carlo simulations were used to account for the uncertainties in the number of people actually exposed. The results of the study imply that the quick clay fatality curves are non-linear, indicating that the probability of losing lives increases exponentially when the number of exposed persons increases. Potential factors affecting human susceptibility to landslides (e.g., landslide-, area-, or individual-specific characteristics) could not be satisfyingly quantified based on available historical records. Future research should concentrate on quantifying susceptibility factors that can further explain human vulnerability to quick clay landslides.