Today: 317 Years Since Last Subduction Zone Quake

January 26, 2017

8am Thursday…

The weather is quite slow again today with areas of morning fog/clouds leading to at least partly cloudy conditions this afternoon.  A little more easterly flow Friday through Sunday SHOULD give us more sunshine.  We’ll see how that works.  The next chance for a real soaking isn’t going to be until February!  That would be next Wednesday of course.

As of Wednesday, January is the 5th coldest month on record here in Portland.  We still have 6 relatively mild days to go, but we could easily end up with the coldest month since 1990 here in Portland and one of the top 10 coldest months!

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On another note, today is the anniversary of the last great Cascadia Subduction Zone earthquake.  It was in the evening, January 26th, 1700.  Geologists tell us it was likely at least a 9.0 magnitude quake just offshore.

How do geologists know?

If you have some time take a look at this info on the Orphan Tsunami of 1700 .  I think it’s fascinating reading, but of course I find almost anything scientific to be fascinating.  It’s a paper written by Brian Atwater  and others about the clues to a massive West Coast earthquake, summarized in the graphic below

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Some have theorized the massive Bonneville Landslide and the resulting “Bridge of the Gods” in the central Columbia River Gorge could have been triggered/formed by the big quake, but it appears maybe it is too old for that to be the case.  Great reading again just on the Wikipedia link.

Enjoy the weekend!

Chief Meteorologist Mark Nelsen