DÖLF BARBEN People tend to associate tsunamis with oceans. Many will recall the devastating Indian Ocean tsunami that killed around 230,000 people on 26 December 2004, triggered by an earthquake off the west coast of Indonesia. But tsunamis in Switzerland? That scenario is nowhere near as improbable as it may seem. “The danger is real,” says professor of geology at the University of Bern, Flavio Anselmetti, who has been studying this possibility with the help of colleagues from Berne and ETH Zurich for over 10 years. Probably no other tsunami in Switzerland has been documented to such a degree as the one that occurred on 18 September 1601 on Lake Lucerne – also after an earthquake. “With a (reconstructed) magnitude of 5.9, the quake violently shook the whole of central Switzerland. Trees and houses were uprooted, mountainsides crumbled.” This quote is from a Swiss National Museum blog post written by 32-yearold historian Noah Businger, who found out about the event while studying at university. Businger, who hails from central Switzerland, was eager to learn more and has proceeded to supplement historical knowledge with the latest research. No singing or shouting Lucerne’s official chronicler Renward Cysat (1545–1614) recorded details of what happened. Waves up to five metres high crashed into the shoreline near Buochs, penetrating as far as one kilometre inland. At least 10 people died. Boats were swept well beyond the shore. In Lucerne, the water in the River Reuss was repeatedly drawn right out into the lake only to suddenly come rushing back in again. This was what we would now call a seiche, or standing wave, where all the water oscillates back and forth from one side of the lake to the other as if it were in a bathtub. The locals had no idea what had hit them. “It must have been terrifying,” says Businger. People thought it was God’s punishment for their sins. The authorities sought to placate the Almighty and banned excessive feasting and celebrating as well as dancTsunamis on Swiss lakes – “the danger is real” In 1601, at least 10 people lost their lives in a tsunami on Lake Lucerne that was triggered underwater after an earthquake. Could such a disaster happen again? ing, singing and shouting for several months. But what exactly had happened? Scientists now know, thanks not least to what Cysat wrote. The boats had run aground as much as “two halberds” – roughly four metres – above the normal waterline, making it possible to deduce how high the waves would have been. Talking to Flavio Anselmetti, however, it becomes clear that the earthquake did not cause the tsunami directly. “Like a slab of snow that comes loose” Many of the slopes surrounding the lake basin at Buochs continue for 200 metres underwater, where large amounts of mud and rock would have piled up over many centuries. The earthquake sent much of this material sliding. Anselmetti: “It was like a slab of snow coming loose.” Multiple sediment avalanches descended to the bottom of the lake, pushing water upwards – after having pulled water downwards into the space it had left behind. Lake Lucerne would have been in tumult. Higher, farther, faster, more beautiful? In search of somewhat unconventional Swiss records Today: extreme waves Many of the slopes surrounding the lake basin at Buochs continue for 200 metres underwater, where large amounts of mud and rock would have piled up over many centuries. Photo: Keystone Swiss Review / October 2026 / No. 4 22 Knowledge
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