JP5 Tsunamis (IAPSO, IASPEI)

Joint Inter-Association Symposium

28-Jun-2015, 16:30 - 18:00

Abstract content:

Understanding tsunami hazard and risk in lakes: the case of western Lake Geneva

Catastrophic events linked to tsunami waves, such as the Tohoku-Oki Tsunami (2011), have raised strong societal interest in understanding and assessing risk associated with these phenomena. However, killer waves are not only restricted to oceanic water bodies but can also occur in lakes.

This research focuses on tsunami risk assessment for the shores of Lake Geneva (France – Switzerland) region. Indeed, previous seismic and sedimentological studies have shown that at least six sublacustrine mass failures triggered tsunamis in Lake Geneva, during the last 4000 years. Numerical simulations of the most recent event (563 AD) show wave heights exceeding 8 meters at the end of the Western Lake.

Since this event, Lake Geneva region has become a major economic and urban area with most of its shore urbanized. However, no tsunami early warning system and little or no awareness of tsunami risk exist. It is therefore of prime importance to better understand the possible consequences of tsunamis in lakes.

The study is based on two step assessments: the hazard and the exposure carried out within a GIS environment, in order to identify sensitive locations in space. The hazard assessment has been carried out using a new physical tsunami wave model based on a Non-Oscillatory central differencing scheme. Output of this model are expressed in terms of wave height, propagation speed and inundation zone. Exposure considers the population, the buildings and the infrastructures at risk in the Western Lake Geneva region.

Our work shows that a tsunami on Lake Geneva could have disastrous consequences. This is mainly due to the combined effects of (1) short wave arrival times (2) significant exposure (3) little or no awareness of the tsunami risk and (4) the lack of an early warning system.

C. Calpini1, G. Simpson1, C. Frischknecht1, S. Girardclos1,2.
1Earth and Environmental Sciences, Earth Sciences, Genève, Switzerland.


Tsunami     Lake     Geneva     Risk