By Felix Würsten

It was a harsh blow for limnogeologists at ETH Zurich. In April 2002 a fire, the cause of which is still not known, destroyed the research vessel "Tethys", which was anchored in the harbour at Zurich-Wollishofen (1). Now researchers have a worthy successor. Last Thursday, in a festive ceremony at the Barfuss Bar of the women's lido, they christened their new motorboat "Arethuse".

From mother to daughter

It was a stormy christening. Shortly after the guests had assembled a heavy thunderstorm passed over Zurich bringing high winds and hail. It failed to dampen the celebrants' good cheer, especially as the rain had disappeared by the time Judith A. McKenzie and Flavio Anselmetti of the Geological Institute accompanied by Barbara Haering, Member of Parliament, led the company to the boat.

The new emblem of the Limnogeology Laboratory, a Finnish ship "Tarfish 700", was keeled at the Faul wharf in Horgen. The name Ar-ETH-use was chosen because first of all, it includes the letters "ETH", and because it is a reminder of the destroyed vessel "Tethys", says McKenzie. Arethuse is the Greek nymph of water and Tethys the mother of all sea nymphs. The acquisition was jointly funded by ETH and PartnerRe.

Research into catastrophes

There is a good reason why an important reinsurance company, like PartnerRe should act as sponsor for such an undertaking. Amongst other things, PartnerRe insures against damage caused by natural catastrophes. For this reason the company is very interested in research that helps it to manage risk by assessing the probability of major catastrophes.

"Arethuse", the new flagship of the Laboratory of Limnogeology large

Judith McKenzie, Barbara Haering and Flavio Anselmetti at the christening ceremony large

This is precisely the kind of research, as Anselmetti explains, the ETH limnogeology group carries out. Using the boat, researchers can gather samples of sediment from the bed of a lake. Fine layers of sediment layers that have been stored and stratified over the years on the bed can then be used to reconstruct past climate.

Treacherous tidal waves

For example, light coloured layers in the samples are evidence of heavy rainfall and flooding because they cause unusually high amounts of sediment to be washed into a lake. Earthquakes, too, leave traces behind in the form of less compact stratification, because heavy quakes can trigger underwater slides. Such slides can be very treacherous because in their turn they can trigger huge tidal waves, so-called tsunami that can spread across the lake. Such waves were occasioned, for example, during the heavy earthquake of 1601 in the Lake of Lucerne in Central Switzerland. Disturbances in the sediment layers can help researchers to estimate the frequency of heavy earthquakes.

Strong and handy

The new boat might not be as elegant as its predecessor, but it is better adapted to research purposes. In contrast to Tethys, Arethuse has no cabins under the foredeck. This means that it is easier to move around on the boat. One important criterion for the choice of the boat was that it can easily be transported from one lake to the next on a trailer.

In coming months Arethuse will be travelling around Switzerland on a short tour, as Anselmetti tells us. Investigations are planned for the Lake of Lucerne, as well as the lakes of Brienz and Zurich.