HONOLULU -- On the south side of the Hawaiian island of Kauai lies Makauwahi, a massive cave and sinkhole where scientists have uncovered evidence of an enormous tsunami that struck Hawaii about 500 years ago.
Triggered by a 9.0-magnitude earthquake off the coast of the Aleutian Islands in Alaska, the tsunami likely brought waves up to 30 feet -- enough to devastate Hawaii's coastal populations, infrastructure and economy today.
A new study says there's a chance it will happen again within 50 years.
The study, published Friday in the Journal of Geophysical Research, involved a team of researchers at The University of Hawaii at Manoa who analyzed fault length and plate-convergence rates to estimate the likelihood of a mega-earthquake (magnitude 9 or greater) in the Aleutian Islands.
The findings suggest there is between a 6 percent and 12 percent chance of a mega-earthquake striking the Aleutians and causing a tsunami in Hawaii in the next 50 years. If and when it happens, it could cause some $40 billion in damage and affect 400,000 residents and tourists.
Lead author Rhett Butler, a geophysicist at the UH School of Ocean and Earth Science and Technology, said in a statement that he and his team devised their model precisely because Hawaii has no recorded history of mega-tsunamis.
“Necessity is the mother of invention,” Butler said.
The researchers validated their model by using data from the five largest tsunamis since 1900 -- Kamchatka, 1952; Chile, 1960; Alaska, 1964; Sumatra-Andaman, 2004; and Tohoku, 2011-- as well as evidence found in geological samples, including some from the Makauwahi sinkhole.
The team said it hopes the findings will help Hawaii officials prioritize the potential of a tsunami threat with other risks. It is also considering ways to estimate the threat of smaller-magnitude earthquakes in the Pacific.