Experts say it will happen again with a 10-15% chance of a mega earthquake in the next 50 years
CORVALLIS, Ore. -- The 323-year anniversary of the last major earthquake and tsunami that hit Oregon was Thursday, January 26, 1700.
Experts say it will happen again, with a 10-15% chance of a mega earthquake in the next 50 years.
Oregon State University Marine Geologist Chris Goldfinger says on a scale of 1-10, with 1 being not prepared and 10 being fully prepared, we are at a 1.5 in terms of being ready for the next earthquake and tsunami.
“So far the evidence that these events happened across the full length of the Cascadia Margin is very strong and almost as airtight as you can get in geology," Goldfinger said.
He says sediment deposit readings show evidence of an undersea landslide that occurred over 300 years ago. That would be consistent with a mega earthquake.
He also says there is evidence in Japan from a distant tsunami from that same day.
Tree ring data from a ghost forest along the Oregon coast shows that around 1700, the trees stopped growing and suddenly died, which Goldfinger says would be caused by the land dropping 6 feet, which flooded the trees with salt water and killed them.
Looking ahead, Goldfinger gives a 10-15% of a megathrust earthquake and tsunami in the next 50 years.
“What you would get is a minute or two of light shaking. It would feel like someone was jack hammering out in the street and everyone would be looking around wondering what it was,” he says.
“That shaking comes from the initial P-Waves. Then the S-Waves come a minute later and that’s where the real shaking starts to happen," he continued... It’s not a movie tsunami. It’s a series of waves that could take up to an hour or several hours to play out," Goldfinger said.
Pedro Lomonoco, the director of the Hindale Wave Research Laboratory in Corvallis, says we would need to retrofit our infrastructure to withstand a magnitude 9 earthquake.
“The houses that are less strong are going to be easily destroyed,” Lomonoco said.
He says a big priority should be building homes along the coast with stilts.
“What happens when you have a space that allows the water under the structure to go through,” he said.
This also means that businesses, such as schools and hotels, that are in the tsunami inundation zone should be built with an evacuation area on the roof where people can go in a tsunami warning.
Already, schools in seaside Oregon have been made vertical evacuation structures in the event of a tsunami.
“This is a solvable problem; we’ve discussed we have this big problem but it does have a solution. The solution is expensive and time consuming and require steady effort to solve,” Goldfinger says.
