High Potential for Pacific Tsunamis Discovered

Experts from the Durham University in the United Kingdom, the University of Utah and Plafker Geohazard Consultants have recently finished conducting a new study on the west coast of North America, which has concluded that the potential for devastating tsunamis is much larger than originally estimated. The team believes that the damages the coastline is looking at may be far more widespread and deep than the ones caused by the 1964 Alaskan earthquake, which killed 130 people and caused extensive damage in Alaska, British Columbia, and the US Pacific region.

Working alongside the Alaskan coast, experts from the three institutions probed the underground layers of deposits, in search of pieces of evidence of earthquakes that struck the region over the millennia. According to statistics, the 1964 earthquake, at its 9.2 degrees of magnitude, generated waves as high as 9.2 meters in the Alaskan Gulf, and as high as 52 meters in the submarine slide in Valdez Arm.

The new study seems to suggest that larger areas of the ocean floor could rupture then the 800-km-long one from 1964, and that the adjacent 250-km-long Yakataga segment to the East could also manifest itself at the same time. If the two gave way together, then the ensuing tsunami would be unlike any other in recorded history. The paper accompanying the finds was published in the latest issue of the academic journal Quaternary Science Reviews. The work was funded by the National Science Foundation (NSF), NASA, and the US Geological Survey (USGS).

“Our radiocarbon-dated samples suggest that previous earthquakes were fifteen percent 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 and the Pacific region as a whole,” Ian Shennan, professor in DU’s Geography Department and the lead author of the study, explains.

“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. 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 adds.

“A large scale earthquake will not necessarily create a large wave. Tsunami height is a function of bathymetry, and the amount of slip and dip of the faults that take up the displacement, and all these factors can vary greatly along the strike. Tsunamis will occur in the future. There are issues in warning and evacuating large numbers of people in coastal communities quickly and safely. The US has excellent warning systems in place, but awareness is vital,” Plafker Geohazard Consultants expert Dr. George Plafker shares.

He believes that existing evacuation routes and contingency plans in effect in the US are more than apt to make people aware of an incoming danger, but he underlines the fact that the evacuation plans need to be reworked, so that more people could escape in the event of a larger wave. A large tsunami in the middle of the Pacific could take up to two and a half hours to get to Alaska, Canada, and the US west coast.