New evidence suggests that a mammoth tsunami ravaged Hawaii hundreds of years ago, a phenomenon that could possibly happen again in the future.
In April 1946, an 8.1 earthquake near Alaska's Aleutian Islands resulted in destructive water waves up to 10 feet high surging into Hawaii Island, killing over a hundred people and causing $26 million worth of damages.
Findings of a new study, however, indicate that the 1946 Hawaiian tsunami, known to be the most destructive in the island's recent history, pales in comparison with a monster tsunami that surged across Hawaii's island of Kaua'i about 500 years ago.
The tsunami, which occurred sometime between 1425 and 1665 A.D, was triggered by a powerful 9.0 earthquake that hit Alaska sending waves up to 30 feet high toward the shores of Hawaii and leaving behind fragments of sea objects such as mollusk shells, coral fragments and coarse beach sand in a sinkhole in Kaua'i.
In a new study published in Geophysical Research Letters on Oct. 3, Rhett Butler, from the Hawaii Institute of Geophysics and Planetology at the University of Hawaii in Honolulu, and colleagues used wave models to predict how a tsunami could have flooded Kauai's Makauwahi sinkhole, a collapsed limestone cave whose mouth is separated from the present-day shore by 328 feet of land and is 23 feet above sea level, indicating the possibility that the enormous amount of ocean deposits found there were brought and left by a massive tsunami.
The researchers found that the geometry of the eastern Aleutian Islands is arranged in such a way that it can produce a monster tsunami that would hurl toward the Hawaiian Islands. An earthquake with a magnitude of at least 9 could generate water levels on shore that range between 26 to 30 feet high, which is more than enough to fill the Makauwahi sinkhole.
"A preponderance of evidence indicates that a giant Mw ~9.25 earthquake centered in the eastern Aleutians occurred ~350 to ~575 years ago," Butler and colleagues wrote. "The model-forecast tsunami from this event exceeds all historical tsunamis in the Hawaiian Islands in the last 200 years."
Pacific Tsunami Warning Center geophysicist Gerald Fryer said that mammoth tsunamis such as the one that occurred 500 years ago rarely occur. They could only happen once every thousand years, but there is still a 0.1 percent probability that it could happen; the chances are the same as the likelihood for the 9.0-magnitude 2011 Japan earthquake and tsunamis.
