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‘Strong’ tremors recorded for the past week under Hood Canal

A "slow slip" event continues to produce small tremors in the Puget Sound region. (PNSN)

There’s little doubt in local seismologists’ minds that the numerous tremors recorded in the Puget Sound region over the past several days are related to a phenomenon that some say increases the risk of a major earthquake.

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Just how much the event increases the risk of a mega-quake is up for debate, but one thing is for sure, the tremors are spreading.

“Just over a week with strong tremor[s] every day and spreading mostly north,” the Pacific Northwest Seismic Network wrote on its blog.

About every 14 months, the Cascadia Subduction Zone that stretches from Northern Vancouver Island to Cape Mendocino, Calif., experiences an episodic tremor and slip, or “slow slip” for short. During these events, the Juan de Fuca Plate moves westward and adds stress to the Cascadia Subduction Zone some. Some scientists believe the 620-mile subduction zone is at slightly higher risk for a major earthquake.

The last slow slip event was recorded around the end of December 2015 through January 2016.

If you asked seismologist Alison Bird, of the Geological Survey of Canada, the heightened risk of a “megathrust” quake is like driving in rush hour traffic, compared to driving in the country on a Sunday. Here’s what she told CBC:

Going for a drive in the country on a Sunday, you’re not that likely to be in a car accident. But if it’s rush hour in Vancouver and there’s a game on … you’re more likely to be in an accident. You’re not necessarily going to be, but the probabilities are higher.

Down in Seattle, Ken Creager, an earth sciences professor at the University of Washington, says the event isn’t anything worth wringing your hands over. Though he said there is reason to believe the changes are higher, it’s still “highly unlikely,” he told Patch.

On Feb. 25, University of Washington Professor of Seismology John Vidale noted the tremors are spreading north and south — as far north as the Strait of Juan de Fuca and as far south as Olympia.

A 4.2 magnitude earthquake near Belfair was the most notable event in Washington during the timeframe of the slow slip. Thousands of people reported feeling the quake.

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