July 20, 2009

Pacific tsunami risk greater than thought

The potential for a huge tsunami on the West Coast of North America warrants immediate review of regional evacuation plans, geologists said.

A future tsunami could be far larger than the one generated by the great 1964 Alaskan earthquake, which sent huge waves as far south as Northern California, University of Utah geologist Ron Bruhn said.

Bruhn's team gauged the power of earthquakes, and resulting tsunamis, by studying 2,000 years of subsoil along the Alaskan coast. Radiocarbon-dating layers within the subsoil suggests earthquakes in Alaska could rupture even larger segments of the sea floor than previously thought, Bruhn said.

Tsunami warning systems have been in place on the West Coast of North America and Hawaii since the 1946 Aleutian Islands tsunami, and improvements were made after the 2004 tsunami in the Indian Ocean that killed more than 230,000 people.

What's needed now is a thorough review of coastal evacuation plans from Alaska south to California, said Bruhn, who conducted his study with researchers at England's Durham University.