Wednesday, March 30, 2011

Tsunami reprise

When I said earlier that the tsunami was not detectable in Puget Sound, I meant that *I* did not sense it.  However King County's instrumentation did, as I mentioned in a comment on that earlier posting.  My daughter Erica, who works for King County Environmental, sent me this chart:
The tidal cycle shows clearly, of course.  But notice the jaggedness on the peaks beginning between 3/11 and 3/12?  (You might want to click on it to get a larger version.)  That is the tsunami.  The instrumentation only responds to very long-period waves, so wakes from ferries (or fairies, Mr. Rawles!), shipping, etc are ignored.  The number and duration of jags shows that the wave sloshed around in Puget Sound for more than two days before it's amplitude fell below the instrument's detection limit. 

Thought you might be interested.

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