New Study finds mega-tsunamis pose potential threat to Hawiian Islands

SAN FRANCISCO — It's almost unimaginable: a tsunami more than 1,000 feet (300 meters) high bearing down on the island of Hawaii.

But scientists have new evidence of these monster waves, called megatsunamis, doing just that. The findings were presented here yesterday (Dec. 5) at the annual meeting of the American Geophysical Union.

Unlike tsunamis from earthquakes, the Hawaiian tsunamis strike when the island chain's massive volcanoes collapse in humongous landslides. This happens about every 100,000 years, and is linked to climate change, said Gary McMurtry, a professor at the University of Hawaii in Honolulu.

Sitting about 30 feet (10 m) away from today's Ka Le (South Point) seashore are boulders the size of cars. Some 250,000 years ago, a tsunami tossed the enormous rocks 820 feet (250 m) up the island's slopes, said Fernando Marques, a professor at the University of Lisbon in Portugal. (The boulders are closer to the shore now because the main island of Hawaii is one of the world's largest volcanoes, and its massive weight sends it sinking into the Earth at a rate of about 1 millimeter a year.)
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