For several decades, scientists have been developing a theory: 500 years ago, an earthquake in Alaska triggered a massive tsunami that hit Hawaii with waves up to 30 feet high—three times the size of the largest recorded tsunami in the state's history.
A team of researchers, led by University of Hawaii geophysicist Rhett Butler, published their findings in Geophysical Research Letters, a journal of the American Geophysical Union (AGU). In a press release, the AGU described how the so-called great Aleutian tsunami first came to scientists' attention when fragments of coral and other ocean debris were discovered during the 1990s excavation of a sinkhole in southern Kauai.
New theory substantiated by 2011 Tohoku earthquake and tsunami
The initial evidence was inconclusive and researchers are still searching for answers, but a breakthrough came in 2011 after the Tohoku earthquake unleashed a 128-foot tsunami on northeastern Japan. Butler, the lead researcher on the new tsunami study, said the 2011 event was "bigger than almost any seismologist thought possible." In the aftermath, scientists began to rethink their established risk forecasts and public safety plans in vulnerable areas such as Hawaii.
This turn of events boosted the credibility of the mammoth tsunami theory in Hawaii and provided a wealth of new information about how those events work in practice. Butler's team developed a new wave model to show how a large earthquake in the Aleutian-Alaska zone where the North American and Pacific tectonic plates meet could send a tsunami of the right size toward Hawaii. The researchers also began searching for other debris that may have come from the same event.
Stakeholders adapting to heightened awareness of tsunami risk
For an independent perspective on the new findings, the AGU spoke to geophysicist Gerald Fryer at the Tsunami Warning Center in Ewa Beach, Hawaii. Fryer said that an event of the scale described by researchers is unlikely to occur in any given year, but there is enough of a risk that it must be taken seriously.
Given the extent of modern residential and commercial development in Hawaii, this type of event would be devastating if it occurred today. Officials in Honolulu have already revised their evacuation maps to account for the possibility of larger tsunamis. They intend to distribute the updated maps by the end of the year.
Homeowners and insurance carriers have roles to play in ensuring that vulnerable communities are prepared for a tsunami, or any other disaster. Keeping valuations for insured structures accurate and up to date can facilitate the recovery process and help affected home and business owners get back on their feet.
Interested parties can read the full report on the great Aleutian tsunami here.