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Content - Switzerland also conducts tsunami research

  • October 15, 2018

Switzerland also conducts tsunami research

Tokyo (SCCIJ) – Switzerland and cheese is a well-known combination, but Switzerland and tsunami does not look like such a “natural” pair because Switzerland has no maritime borders. But largely unknown outside of Europe, there are earthquakes in Switzerland due to some faults under the Alps. As a result, there have been tsunamis in Swiss lakes in the past. This is the reason why researchers from ETH Zurich and the University of Bern are now studying lakes in Switzerland to learn about tsunamis and their hazard, what triggers them and how often they have occurred in the past.

Tsunami research in Swiss lake

Tsunami project Vierwaldstättersee

It has been more than 400 years since a tsunami flooded the banks of Lake Lucerne and the city of Lucerne. The tidal wave was caused by a 5.9-magnitude earthquake, which triggered several underwater landslides as well as a rockslide on the Bürgenstock. These events subsequently caused a shock wave that spread across the entire lake. Based on historical records, it was estimated that the wave was four metres high: near Ennetbürgen, reports describe flooding “1,000 paces or three rifle shots” into the hinterland. 

Today, the lowlands and shores around Ennetbürgen are fully civilized: the shore is dotted with buildings, a marina, a camp site and a water sports centre, while intensively used meadowland stretches far into the hinterland. The risk of tsunamis on Lake Lucerne and other Swiss lakes has not disappeared, however, and the one in 1601 was not a one-off event. They happen rarely, but the possibility cannot be fully ruled out. 

Researching tsunami hazards

This is why researchers from ETH Zurich, the University of Bern and the Center for Marine Environmental Sciences in Bremen began a major research project to learn about the hazards posed by lake tsunamis, how often they have occurred in the past, what triggers them and what effects they have. 

The project focuses on taking seismic measurements in Lake Lucerne. The researchers place special underwater seismometers in various locations to obtain seismic and geotechnical measurements on the lake floor. 

They are also studying landslides in river deltas. In 1687, for example, sections of the Muotha delta slid, causing a tidal wave on Lake Lucerne. By examining cores drilled on the shoreline and in the lake bed, researchers are searching for deposits caused by tsunamis. They are also using computer models to simulate how tidal waves might spread across the lake. 

Extensive sediment testing

ETH professor Donat Fäh is in charge of the main part of the project. Fäh is Head of the Earthquake Hazard & Risk Assessment Section for the Swiss Seismological Service. He plans to closely examine the internal structure, volume and properties of lake sediments. The researchers also want to learn what processes unfold in the sediments and how stable they are. They hope to develop a geophysical and geotechnical 3D model to study the propagation of seismic waves or deformations caused by earthquakes, for example. Finally, they also want to develop computer simulations for earthquake scenarios. 

Another goal for Fäh and his colleagues is to improve the quality of observational data, specifically by upgrading the existing seismic monitoring stations and creating new ones. There are plans to install 70 new stations by 2020. The observational data should allow researchers to better analyse seismic hazards. This project is part of a larger Swiss research program, which aims to understand how the local subsoil affects the earthquake hazard and phenomena caused by earthquakes, such as soil liquefaction or landslides. 

A classic study of natural hazards

“This project is a classic study of natural hazards for Switzerland,” says Flavio Anselmetti, who is a geology professor at the University of Bern and is in charge of the tsunami project together with Donat Fäh. He adds that lakes also offer a perfect model for understanding oceans, and the knowledge they hope to gain from this project is likely to be applied to ocean phenomena as well. To help cover the total cost of CHF 2 million of the tsunami research project, the Swiss National Science Foundation is funding it as an interdisciplinary, multi-university Sinergia project. ETH Zurich and the Federal Office for the Environment are also providing funding.  

 

Text and photo: © Peter Ruegg/ETH Zurich

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