A danger is lurking in the bucolic mountains of Switzerland: the alpine lake tsunami. Yes, it’s a real thing, and yes it has happened before — many times, according to unsettling new geological research.
Like a tsunami in the ocean, a lake tsunami is the result of an earthquake under the water. Rocks and sediments might shift, creating a huge wave that sloshes around in the enclosed lake. “The same source placed inside a lake can have a bigger impact than along the coast of an open ocean,” Hermann Fritz, a tsunami research, tells Nature.
Lake tsunamis have killed before, like at Lake Yanawayin in Peru in 1971, where 400 to 600 people died. And geologists are aware of the risks of lakes near faults, such as Lake Tahoe in California. But the alpine lakes of Switzerland were never singled out for tsunami risk until two years ago, when limnogeologist Katrina Kremer and her colleagues published an unsettling study about a tsunami that wiped out the area around Lake Geneva in the year 563.
As Nature reports, Kremer’s team has now studied lakebed sediment cores and identified a total of five likely tsunamis in Lake Geneva’s past 4000 years. It’s rare, but it’s still common enough to worry inhabits (and insurance companies). Other lakes in the region show evidence of tsunamis, too.
Nidwalden, a canton that borders Lake Lucerne, has commissioned geologists to study the landscape in and under the lake to predict tsunami scenarios. The assessment will guide future construction plans in the area. Humans have shown a stubborn persistence to keep living in seismically active zones, and if that’s the case, we might as well be prepared. [Nature]