First-order loss estimation for subaqueous mass-movement generated tsunamis on perialpine lakes

Abstract

Abstract Subaqueous mass movements can trigger tsunami waves not only in the oceans, but also on lakes. For a few Swiss perialpine lakes, tsunamis have been documented in historical reports (e.g. Cysat 1969; Favrod 1991), mainly caused by earthquake-triggered subaqueous mass movements. In addition, results from numerical modelling show that tsunamis may occur again on perialpine lakes (e.g. Hilbe and Anselmetti 2015). To be prepared for such events, a quantitative risk assessment is essential. Although several authors have tried to quantify marine tsunami risk, the possible impact of lake tsunamis remains understudied. Herein, we leverage recent work that modeled possible earthquake-triggered mass movement tsunami scenarios on the well-investigated Lake Lucerne in Switzerland and proceed to obtain some fist-order estimates of possible earthquake- and tsunami-induced economic losses. We use tsunami intensity footprints, in terms of flow depth and momentum flux, conditional on subaqueous mass movements triggered by 475- and 2475-year ground motions. These are overlaid with the built exposure at the village of Buochs-Ennetbürgen, located at the shore of Lake Lucerne. Earthquake and tsunami damage is computed based on fragility and consequence information retrieved from the Earthquake Risk Model of Switzerland (ERM-CH23) and the HAZUS tsunami model. Earthquake and tsunami losses are further contrasted and discussed. This work provides a first analysis of the tsunami risk around perialpine lakes.