Hunting Archeo-Tsunamis

October 30, 2008

The catastrophic Indian Ocean tsunami four years ago has done one very important thing for tsunami researchers: Given them a view of exactly what a bona fide vast tsunami looks like in the sediments it leaves behind. That has led to some big advances in searching for signs of past tsunamis. There's a nice bit of news on this matter here from this week's Nature.

But here is the back story: For years the difficulty with studying tsunami sediments -- those created by the waves washing over barrier islands and into bays, for instance -- has been pinning them to tsunamis. How do you distinguish them from sediments left by powerful storms? Since researchers would like to know more about the "deep time" frequencies and risks of both big cyclones and tsunamis, it's imperative that they be separated in the sediments. That's where the 2004 event provided a windfall of data from a wide area all over the Indian Ocean. Among the most surprising finds was that the tsunami actually managed to increase the height of some of the Maldives islands (shown to the left). Wonders never cease!