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Pacific Northwest to be hit by hundreds of tremors over a number of weeks

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Summary

'Every 14 months, we get hundreds of tiny earthquakes,' says an SFU prof

Science is still developing, when it comes to predicting how much risk of major quake goes up during slow-slips

VANCOUVER (NEWS 1130) – The Pacific Northwest will soon be at a greater risk of an earthquake.

Both British Columbia and Washington state will soon be entering a slow-slip event, which actually occurs with surprising regularity.

“It means that about every 14-months, we get hundreds of tiny earthquakes, they call them tremors. You can’t feel them, they’re below the threshold that someone on the earth’s surface could feel them. They occur very deep within the crust of the earth,” explains John Clague, an earth sciences professor at Simon Fraser University.

The next seismic cycle is expected to begin on April 18th though the date is somewhat fluid. It happens because of the stress built up where the Juan de Fuca and North American plates connect in the Cascadia subduction zone.

“They’re kind of scary because they are so regular. We think they are related to the build-up of stress that occurs where the two plates that are colliding off our shores are coming together,” says Clague.

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The science is still developing, when it comes to predicating by just how much the risk factor of a major earthquake occurring increases during the slow-slips.

“You reach a point where it takes trivial event. It’s kind of like the straw that breaks the camel’s back that leads to a full-scale rupture and a magnitude 8 or 9 earthquake,” says Clague.

“The thinking is that we have an increased possibility that one of these events will lead to the full-scale rupture during one of these cycles, these 12 to 16-month cycles.”

Similar events happen along other fault lines across the world, most notably near Japan. But when they’re over, says Clague, they’re over quickly.

“The earthquakes stop. It’s crazy. You get hundreds of these earthquakes, it’s like they light up the seismometers and then they just stop. It’s a little frightening, actually. We don’t feel it.”

There is still a lot to learn about the phenomenon, and Clague say though many people may not know about the regular occurrences, it important to spread the word.

“I think it’s useful to alert people that these cycles do exist. There is an increased likelihood of a big earthquake during one of these cycles. It doesn’t mean that there will be one but probability increases during this short period of time.”