Hard to believe, isn't it? That a wave could be born in a body of water as calm and peaceful as a lake seems improbable. However, tsunamis do not only occur in seas or oceans, but can also form in a lake following an overland or underwater landslide. The first record of a tsunami on a lake in Switzerland dates back to 563 AD. It took place on Lake Geneva, where an immense wave, reaching 13 metres in Lausanne and 8 in Geneva, was apparently caused by a landslide of 50 million m3 of rock in the Chablais region. Following the rockslide, a giant wave crossed the entire length of the lake and reached Geneva, causing catastrophic damage. Earth archives discovered by geologists in 2010, together with literary archives of two bishops describing this disaster, make it possible to date and validate the appearance of this tsunami.
Still not convinced? Other dates marking lake disasters might change your mind. In 1584, following a series of earthquakes in Aigle, a section of mountain collapsed. The tremors were felt throughout the Lake Geneva basin, causing ebbs and flows as far away as Geneva, and claiming around a hundred lives. A few centuries later, in 1806, still in Switzerland, more than 30 million m3 of rock fell from the Rossberg mountain, destroying the village of Goldau and causing a 15-metre-high tsunami on Lake Lauerz! The disaster killed 457 people and reduced the surface area of Lake Lauerz by one seventh. Finally, in 2007, a wave measuring one and a half metres was measured at the port of Weggis, on Lake Lucerne, following a landslide in a former quarry.
Lake Geneva hasn't suffered another event of this kind since the 6th century, but it would seem that we're not safe from another catastrophe. Hopefully a few more centuries will pass before then, so let's continue to enjoy the serenity and calm that our wonderful Lake Geneva has to offer.
Information from the article A tsunami on Lake Geneva?Sylvain Bolt, La Côte, 07.08.2015
For further information: "A giant tsunami on Lake GenevaVideo presenting the exhibition at the Musée du Léman in Nyon, Nouvo, 12.05.2019
Photo credit: ©DR/Collection Bergsturz von Goldau
