Earthquakes are hardly predictable, but a team of researchers says it came up with a “forecast” that estimates the chances of a megaquake striking Alaska’s Aleutian Islands in the next half-century.
Earthquakes are hardly predictable, but a team of researchers says it came up with a “forecast” that estimates the chances of a megaquake striking Alaska’s Aleutian Islands in the next half-century.
After looking at recorded earthquake data, and evidence of “paleotsunamis,” the team led by University of Hawaii at Manoa researcher Rhett Butler pegs the chance of a monster temblor at least 9.0 in magnitude at 9 percent in the next 50 years, give or take 3 percent.
That estimate is important for Hawaii since the state is in the line of fire of tsunamis generated from that region.
The 1946 tsunami that devastated Hilo and killed 159 people was generated by an 8.1-magnitude quake, according to U.S. Geological Survey, off the Alaska coast. The tsunami that killed 61 people in 1960 was the result of a 9.5-magnitude quake in Chile.
While the researchers’ estimate might seem low, Butler noted they’re talking about a wave causing nearly $40 billion in damage and impacting more than 300,000 people in Hawaii, based on recent estimates.
The chance of a megaquake hitting the eastern portion of the Aleutian Islands, the worst-case scenario for Hawaii, is 3.5 percent.
That’s $30 million to $70 million “a year analyzed risk, which is not small,” said Butler, a geophysicist, referring to the chance of a direct hit.
The researchers say the study can help officials better plan for these natural disasters and prioritize their emergency preparations.
“This is a new step forward,” Butler said.
To validate their model, they looked at the five largest earthquakes to hit the Aleutians since 1900 and paleotsunami data, researchers say.
“These five events represent half of the seismic energy that has been released globally since 1900,” Butler was quoted as saying in a press release. “The events differed in details, but all of them generated great tsunamis that caused enormous destruction.”
UH researchers also are working with state Civil Defense officials to prepare for such a mammoth tsunami, known as the Great Aleutian Tsunami, by developing new inundation maps.
While existing tsunami warning signs aren’t expected to change, a separate and much larger evacuation area might be set aside for when the ‘big one’ strikes.
These “extreme evacuation zones” were unveiled on Oahu last year. Officials are still drafting such zones for Hawaii Island.
Email Tom Callis at tcallis@hawaiitribune-herald.com.