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Martina Sttele I Michael Krautblatter I Michael Brndl I Daniel Straub
Landslides (2016) 13:737750DOI 10.1007/s10346-015-0605-2 Received: 23 December 2014Accepted: 29 June 2015Published online: 15 July 2015 The Author(s) 2015This article is published with open access at Springerlink.com
Abstract Warning systems are increasingly applied to reduce damage caused by different magnitudes of rockslides and rock-falls. In an integrated risk-management approach, the optimal risk mitigation strategy is identified by comparing the achieved effectiveness and cost; estimating the reliability of the warning system is the basis for such considerations. Here, we calculate the reliability and effectiveness of the warning system installed in Preonzo prior to a major rockfall in May 2012. BReliability^ is defined as the ability of the warning system to forecast the hazard event and to prevent damage. To be cost-effective, the warning system should forecast an event with a limited number of false alarms to avoid unnecessary costs for intervention measures. The analysis shows that to be reliable, warning systems should be designed as fail-safe constructions. They should incorporate components with low failure probabilities, high redundancy, have low warning thresholds, and additional control systems. In addition, the experts operating the warning system should have limited risk tolerance. In an additional hypothetical probabilistic analysis, we investigate the effect of the risk attitude of the decision makers and of the number of sensors on the probability of detecting the event and initiating a timely evacuation, as well as on the related intervention cost. The analysis demonstrates that quantitative assessments can support the identification of optimal warning system designs and decision criteria.
Keywords Rockfall . Inverse velocity . Warning system . Reliability . Effectiveness
IntroductionMountain regions are prone to gravitationally driven natural hazard processes. Mid- (>104 m3) and high-magnitude (>106 m3) rockfalls and rockslides can cause much damage due to on-site and off-site effects such as inundation, dam failure, and subsequent debris flow activity in released debris (Hewitt et al. 2008). In some areas, especially those affected by melting permafrost and rapid deglaciation, there is increasing evidence for rising frequencies of rock slope failure (Ravanel and Deline 2011; Huggel et al. 2012; Krautblatter et al. 2013). Out of 38 recorded landslide disasters (10001999 AD) that have each caused more than 1000 casualties worldwide, 75 % were...