I wrote about “deep tremors” (also nicknamed “slow earthquakes”) last January, both in this blog and for KPLU. You didn’t feel it, no matter where you live, but the quake happened under western Washington during April and May. That was a couple months earlier than scientists expected. So, they didn’t get their instruments in the ground in time to record it. No matter — the deep tremors come back approximately every 15 months.
There’s a nice write-up by Sandy Doughton in The Seattle Times today. She went on the scene, in Sequim, as the researchers lay down their seismometers in the Olympic forest (great photos, too), and she gives a lengthier explanation of the science behind (or beneath) these episodic tremors.