April 21, 2009

Tsunami Threat From Dominica’s Devil’s Peak

A new study finds that tsunami waves, brought about by the collapse of a volatile volcano in Dominica known as Devil's Peak, would hit the densely populated coast of neighboring Guadeloupe within minutes.

"It's not a case of 'if' this landslide and tsunami will happen, but 'when'," said University of Portsmouth geologist Richard Teeuw, the study's lead researcher, in a statement on Tuesday.

"The trigger will probably be a major earthquake, occurring after the heavy rain and coastal erosion of the hurricane season. It could happen in a hundred years or it could happen next week," he said.

As many as 30,000 residents and tourists along the coast of Guadeloupe, a French territory 30 miles north of Dominica, would have virtually no time to seek safety on higher ground, the study found.

The researchers calculated that a million-ton piece of rock from Devil's Peak set to crash into the sea would create tsunami waves up to 10 feet high.  The landslide would also destabilize an additional three million tons of rock upslope, potentially resulting in even larger waves of up to 16 ft.

The catastrophe would likely result in severe property damage and possible loss of life, the geologists said.

"Guadeloupe is a densely populated island with popular tourist beaches, many of which are wide with low angle gradients," an ideal environment for "tsunami run-up" and larger wave heights, Teeuw told AFP.

"This part of the world is well-prepared for hurricane hazards, but is relatively unprepared for the rapid impact of a tsunami."

Some places have no protection from coral reefs, which might otherwise absorb a proportion of the tsunami's wave energy.

Devil's Peak's unstable rock formation was exposed thousands of years ago after a previous collapse, and coastal erosion has undercut cliffs under the volcano since that time.

Teeuws and his team reached their conclusion after conducting geological surveys supported by 3-D images from Google Earth, which showed clearly visible tension cracks.

An  upcoming survey next year will assess the volcano's seafloor to better estimate the chances of a tsunami event.

Dominica has the highest concentrations of potentially active volcanoes anywhere in the world.  The Caribbean island is consistently exposed to hurricanes and occasionally severe seismic activity.

The study was published in the newsletter of the American Geophysical Union.


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