The last major Cascadia earthquake was 316 years ago - KPTV - FOX 12

The last major Cascadia earthquake was 316 years ago

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PORTLAND, OR (KPTV) -

Tuesday marks 316 years since the last major earthquake hit the Cascadia Subduction Zone off the coast of the Pacific Northwest.

Scientists believe a quake of magnitude 9.0 or higher shook the region in the late evening of January 26, 1700, generating a tsunami that reached all the way to Japan.

How do they know the date, considering the earthquake happened so long ago?

Part of the credit goes to Japan, which has record of a tsunami on that date in 1700 but no reports of a corresponding earthquake.

Scientists have also been able to determine that forests along the coast of the Pacific Northwest were submerged at the same time, according to an article last summer in The New Yorker, which quickly spread fear among many in the Northwest that a devastating earthquake could hit the region anytime.

Scientists have been able to deduce that earthquakes similar to the one that occurred in 1700 have happened every 300 to 600 years or so in the past 3,500 years. Since it's been 316 years since the last one, we could potentially be at risk of a quake hitting at any time.

In recognition of the 1700 quake's 316th anniversary and to highlight the area's risk of another potentially catastrophic earthquake, public agencies from across the Pacific Northwest are holding a Twitter chat Wednesday morning.

You can follow along with the chat by searching for the hashtag #CascadeEQ on Twitter. The chat begins at 10 a.m. Pacific Time.

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