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Friday, November 02, 2012

The Lake Geneva tsunami in the year 563AD.

The Economist Magazine just published an article online entitled "Lake monsters" talks about the Tsunami that was devastated Lake Geneva in the year 563AD, nearly 1500 years ago.
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.
As the article reported "What caused the wave, and the extent of the damage that resulted, have been matters of conjecture for centuries."  Also "Two accounts of the disaster, one by Gregory of Tours and the other by Marius of Avenches, have survived." So
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.

One popular theory was that
this rockfall created a created a natural dam across the Rhône, which held the waters back until it could no longer sustain the pressure. When the dam burst, the resulting wave swept the length of the lake.

Now local researcher at the University of Geneva, Dr.Katrina Kremer,
thinks that the rocks crashed down onto soft sediments which had accumulated at the river mouth because of the slowing of the river’s flow when it enters the lake. These sediments form an underwater delta that has several canyon-like channels. When the falling rocks hit the delta they destabilised the sediments and caused the canyons to collapse. It was this collapse that created the Tsunami.
which is a plausible theory.  I guess developing explanations for ancient happenings is always an academic exerecise of interest. Kremer and colleagues, with the help of information revealed by archaeology are able to formulating a computer model for what might have happened. It's a long article well worth the time to read the details.  The only drawback of models for the times 15 centuries before, similar to some of the climate models for decades in the future, how much can we really take it seriously -- especially when they indicate that might be happening again.  Should anyone would wish to suggest that people reside around the Lake for generations to be evacuated based on the academic exercises?  Well, anyway we have plenty of professional alarmist already!

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