Lake monsters

IN 563AD a tsunami devastated Geneva. Two accounts of the disaster, one by Gregory of Tours and the other by Marius of Avenches, have survived. What caused the wave, and the extent of the damage that resulted, have been matters of conjecture for centuries. But over the past decade several groups of scientists have pieced together the sequence of events and one of those groups, led by Katrina Kremer of the University of Geneva, has now created a computer model of what happened. Unfortunately for the 1m people who live around the lake’s shore, the conclusion of this research is that something similar could easily happen again.

The tsunami of 563 started at the opposite end of the lake from Geneva, at the point where it is fed by glacial meltwater carried into it by the Rhône. Both accounts say the wave began with a massive rockfall on what was then called Mount Tauredunum (this has led to the tsunami becoming known as the Tauredunum event). Tauredunum is thought to be a mountain now called the Grammont, which is located near the river mouth.