Pacific tsunami threat may be greater than previously thought

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Washington, July 21 (ANI): A new study of geological evidence along the Gulf of Alaska coast has indicated that the potential for a huge Pacific Ocean tsunami on the West Coast of America may be greater than previously thought.

The new research suggests that future tsunamis could reach a scale far beyond that suffered in the tsunami generated by the great 1964 Alaskan earthquake.

The study suggests that rupture of an even larger area than the 1964 rupture zone could create an even bigger tsunami.

Warning systems are in place on the west coast of North America, but the findings suggest a need for a review of evacuation plans in the region.

The research team from Durham University in the UK, the University of Utah and Plafker Geohazard Consultants, gauged the extent of earthquakes over the last 2,000 years by studying subsoil samples and sediment sequences at sites along the Alaskan coast.

The team radiocarbon-dated peat layers and sediments, and analyzed the distribution of mud, sand and peat within them.

The results suggest that earthquakes in the region may rupture even larger segments of the coast and sea floor than was previously thought.

The study shows that the potential impact in terms of tsunami generation, could be significantly greater if both the 800-km-long 1964 segment and the 250-km-long adjacent Yakataga segment to the east were to rupture simultaneously.

According to Professor Ian Shennan, from Durham University's Geography Department, "Our radiocarbon-dated samples suggest that previous earthquakes were fifteen per cent bigger in terms of the area affected than the 1964 event."

This historical evidence of widespread, simultaneous plate rupturing within the Alaskan region has significant implications for the tsunami potential of the Gulf of Alaska and the Pacific region as a whole.

"Peat layers provide a clear picture of what's happened to the Earth. Our data indicate that two major earthquakes have struck Alaska in the last 1,500 years and our findings show that a bigger earthquake and a more destructive tsunami than the 1964 event are possible in the future," said Professor Shennan.

"The region has been hit by large single event earthquakes and tsunamis before, and our evidence indicates that multiple and more extensive ruptures can happen," he said.

"If the larger earthquake that is suggested by our work hits the region, the size of the potential tsunami could be signficantly larger than in 1964 because a multi-rupture quake would displace the shallow continental shelf of the Yakutat microplate," said Professor Ron Bruhn from the University of Utah. (ANI)

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