The Really Big One

portland's earthquakeby karlieeee

The New Yorker has a story BY KATHRYN SCHULZ about the coming earthquake that is going to destroy the Pacific Northwest. Who'd a thunk that New York would care about my neighborhood?
      So we've got an earthquake coming, disaster is looming, but as I am fond of saying, the future is cloudy, I cannot see. It might happen in the next few minutes or it might not happen for a thousand years, and if it is later rather than sooner, any number of other disasters could occur that would potentially make the arrival of a really big earthquake a non-event.
      I do have one quibble with the story and that is this line:

"You can spend a lifetime in many parts of the Northwest—several, in fact, if you had them to spend—and not feel so much as a quiver." 

When I was a kid in Seattle we used to have little earthquakes all the time. My mom pointed out that Japan also frequently had earthquakes and Seattle and Japan were somehow related, possibly because we were both on the Pacific Ocean, or because there were a fair number of Japs living in Seattle, or maybe my mother invented plate tectonics, I really don't have any idea. They were small earthquakes. I don't remember feeling any shaking. Of course, that was over fifty years ago and maybe earthquake memories don't last that long. We had one when we lived in Beaverton 20 years ago. It went on for a few seconds, long enough to wake me up out of a sound sleep.

Update: Jack tells me that this was the Scotts Mills Earthquake. The USGS Earthquake site has the specifics:

M 5.6 - Oregon

Time

1993-03-25 13:34:35 UTC

Location

45.035°N 122.607°W

Depth

20.6 km

It was 31 miles away from where I was.

Earlier I found three earthquakes that were right in Portland in the right time frame:

M 3.5 - Oregon

Time

1991-07-22 09:04:38 UTC

Location

45.638°N 122.869°W

Depth

19.8 km

M 3.1 - Oregon

Time

1991-10-18 02:49:51 UTC

Location

45.633°N 122.896°W

Depth

20.2 km

M 3.0 - Oregon

Time

1991-10-21 00:51:01 UTC

Location

45.631°N 122.887°W

Depth

20.4 km

But they were puny, only 1% as strong as the one in '93.

Map of recent local earthquakes

Our house has earthquake ties, bolts I think, that connect the wooden frame of the house to the concrete footers. I suppose that's a reasonable precaution, they probably didn't add more than 0.1% to the price of the house. It won't matter if we get inundated by a Tsunami, or tidal wave, as we used to call them before we got seduced by this nifty foreign word. I suspect that is unlikely, as we are 50 miles from the coast and we have the a range of hills between us and the ocean. Supposedly this area was inundated by the Missoula flood some 15,000 years ago, but I don't expect a repeat occurrence of that event any time soon.

Map of Tsunami Evacuation Zones

P.S. Is anyone offended by the word 'Japs'? It's so much shorter than having to write out 'people of Japanese ancestry'. Of course now I've gone and written it out. It's all my kids fault. They are the local thought crime enforcers, and they are relentless.

Via Captain of the Thought Crime Police.

Update July 14, 2015: Corrected the USGS search results on account of I forgot how to subtract.
Update July 19, 2015: Added Scotts Mills Earthquake information.