Swarm of tremors rumble beneath Central Oregon Coast, could be precursor to the 'big one'

(KATU Photo)

Experts are watching a swarm of tremors along the Pacific Northwest coast, which they say could one day be a precursor to the “big one.”

These tremors are tiny earthquakes that happen while tectonic plates slowly slip past each other. Most of the time they are too small for people to feel.

“Those are just reminders. We don't know what they mean. They are reminders that we are in earthquake country, and they may be precursors to the ‘big one,’” said Scott Burns, a geology professor at Portland State University.

The Pacific Northwest Seismic Network began tracking and mapping tremors along the Cascadia Subduction Zone just recently.

Currently, the tremor swarm is centered around the Central Oregon Coast. These tremors started on the Kitsap Peninsula, moved to Canada, then appeared in Oregon.

Experts say these tremors are a result of a “slow-slip” seismic event. On average, these happen every 14 months. This event appears to have come a little early.

“We've always wondered why, periodically, we've always had these tremors. It's because the plate stops, goes back a little bit, and then continues on,” said Burns.

Burns says these slips may be adding more stress to what is considered a “locked” part of the fault.

“This is all new,” said Burns. “We collect a lot of data. Then when the big earthquake occurs, we go back and say, are there any signals we missed?”

Burns says this is a good reminder to get prepared for a major earthquake.

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