Asteroid Tsunamis Not So Bad After All?

A new computer simulation has determined that if a 200 metre wide asteroid lands in the ocean, where the water depth is 5 kilometres, the following will occur:

• Initial tsunami with a height of hundreds of metres
• The height of the waves makes them prone to collapse, and they start breaking immediately
• After they are 30 kilometres from the impact site, they have shrunk to a height of less than 60 metres
• Extrapolating the shrinkage suggests a height of less than 10 metres after it has travelled 1000 kilometres

Ultimately, how close to the shore the impact is would make a big difference...

Although 10 metres would ordinarily mean massive devastation, apparently the wavelength would be shorter (2 minutes), and therefore not as damaging as regular tsunamis (8 minutes). The results of another simulation "suggest much slower wave decay", ie worse.

The article concludes with something we all, perhaps, should keep in the back of our mind:

Brian Toon of the Universityof Colorado in Boulder says we should continue surveying for asteroids. "We probably have quite a while before we're going to get hit by a significantly sized [asteroid]," he says. "But nevertheless one of these is going to come at us."