The Perils of Freshwater Tsunamis

Abstract

Most people think that tsunamis happen in the sea, but huge events generated by landslides into lakes, rivers, and dams indicate otherwise. For example, during the 563 event in Lake Geneva, a massive fort and numerous towns and villages along its shores were destroyed. There were earlier tsunamis and there will doubtless be more in the future. Indeed, man-made lakes—reservoirs—also represent spectacular dam-building failures. The Vajont Dam in Italy is a story of human folly, a disregard for Nature’s warnings that led to the death of thousands of people downstream. Landslides fall into rivers and can also produce massive waves. New Zealand’s largest historical tsunami was caused by just such a scenario, and although no people died, it offers an ominous sign of what can happen around any water body, fresh or otherwise, in the world.