A "monster tsunami" once struck Hawaii, wiping out much of the life on the island chain, and a similar event could happen again, researchers warn.
A tsunami struck Hawaii in 1946, causing a great deal of damage, but this monster tsunami dwarfed the power of the storm 68 years ago.
The Japanese tsunami of 2011 was accompanied by a water swell of 128 feet in some locations. This event led some researchers to question whether or not the state of Hawaii would be prepared to deal with a similar event. When scientists investigated that question, they came across evidence of a far greater storm.
Marine debris discovered in a massive sinkhole told a tale of a massive storm that took place 500 years in the past. An earthquake in the Aleutian Islands off the coast of Alaska, measuring 9.0 on the Richter scale, formed a massive water swell that reached 30 feet high when it arrived at the island chain. That megastorm was roughly three times more powerful than the 1946 tsunami.
Earthquakes in the Aleutian Island chain powerful enough to cause massive tsunamis happen, on average, about once every thousand years. Even though it may be centuries before such an event were to occur again, such a monster tsunami could hit the islands at any time. This prompted the government of Honolulu to revise their plan for such an event, greatly increasing the number of people in the area who would be subject to evacuation.
"You're going to have great earthquakes on planet Earth, and you're going to have great tsunamis. People have to at least appreciate that the possibility is there," Rhett Butler, geophysicist from the University of Hawaii at Manoa, and lead author of a paper announcing the results of a study on the historic event, said.
The National Tropical Botanical Garden in Kalaheo was being examined by David Burney, a paleoecologist, who discovered large quantities of aquatic debris within a sinkhole there. Similar artifacts found on the continental United States and Canada were compared to the debris found in Hawaii, and dated to the same period. This provided additional evidence such a monster tsunami took place five centuries ago.
"[The authors] stitched together geological evidence, anthropological information as well as geophysical modeling to put together this story that is tantalizing for a geologist but it's frightening for people in Hawaii," Robert Witter, geologist for the U.S. Geological Survey, told the press.
Investigation of the marine debris found in the Hawaiian sinkhole and what it can tell us about the ancient monster tsunami was published in the journal Geophysical Research Letters.
