Seismologist: Oregon earthquakes not a precursor of the ‘Big One’
You can take a breath of relief — the earthquakes that occurred in the Pacific Ocean off the Oregon coast this week are not a precursor of the “Big One.”
Several earthquakes rattled the waters a few hundred miles west of Newport, Ore. early Wednesday morning, ranging from magnitudes of 3.8 to 5.6.
Harold Tobin, director of the Pacific Northwest Seismic Network and a professor in the Department of Earth and Space Sciences at the University of Washington, said these Pacific Ocean earthquakes are very typical and had nothing to do with the Cascadia Subduction Zone, where the North American Plate and Juan de Fuca Plate meet. The Cascadia Subduction Zone is the fault that will one day cause the “Big One” — the 9.0 magnitude earthquake that happens every 300 years or so.
“This is in an area that actually has quite a lot of earthquakes, so this is not at all unusual,” Tobin said of the Oregon coast rumblers, adding, “Earthquakes like this are incredibly common out there — we see them literally every year — and it’s not connected directly to anything that would change the situation with the Cascadia Subduction Zone.”
Tobin said the earthquakes were along the Blanco Transform Fault, between the Juan de Fuca Plate and Pacific Plate.
“I would not see these earthquakes as any kind of a warning sign or a precursor of something happening that we should be more concerned about close to shore,” he said. “This is sort of business as usual for plate tectonics out in the Pacific Ocean.”
Still, Tobin said these smaller quakes are a good reminder to be prepared for that larger earthquake. There is an estimated 15% chance the “Big One” will happen in the next 50 years.
“Any earthquake offshore is just a reminder that we know that there is the potential for a very large and damaging earthquake with a tsunami from the offshore part of the Pacific Northwest,” Tobin said. “It’s not a matter of if, it’s just a matter of when that will happen.”
Tobin said the biggest earthquake mistake that Puget Sound area residents make is not ensuring their houses are in shape to withstand a large quake by, for example, retrofitting older homes. He also noted that local governments need to make upgrades to buildings like schools.
It is also a good idea for individual families to have a go-bag of food, water and supplies on-hand, as well as a plan for where the family members will meet up in the event of a disaster. Tobin’s motto is, “Prepare, don’t despair.”
“We don’t know whether the so-called ‘Big One’ is going to come a hundred years from now or next week, it could happen really in any place in that kind of timespan, so the more preparation you do, the better,” Tobin said. “There are a lot of really substandard school buildings, housing and industrial buildings all around the state … and I’d really like to see all of the different levels of government, and the voters who have to pass bond measures, take that seriously.”