Just wanted to show the current tremor movement over time.
This 1st pic is only showing Vancouver Island and northern Washington envelopes over the past 3 weeks. (There was also tremor that moved north, but I
couldn't get it to process. In fact, the pic below only shows about 1/2 of the epicenter locations.)
Both images are from www.pnsn.org/tremor (dark red color is most recent)
This next pic shows the smaller tremor episode that began a week later in northern California (for the most part) and has marched north into southern
Oregon over the past 2 weeks.
I wonder what the chances are of these 2 packets of tremor meeting in the middle? Say near Portland?
Personally, I don't think the southern bubble of tremor will continue its trek north...but I can certainly be wrong.
At the moment, the tremor under Puget Sound in Washington is particularly strong.
Have a look at the spectrogram from Station HDW
Hoodsport, WA over the past
(click to enlarge)
If you are familiar with those glass-top cooking surfaces, and what happens when you heat a heavy pot on one that has water droplets on the bottom of
the pan--it pops and skitters furiously--that is how I visualize these tremor events. A lot of tiny pops and a bit of slow skitter or shift at the
plate interface, between the under side of the North American continent and the top side of the subducting Juan de Fuca plate. Then the episode ends,
when all of the "water droplets" have evaporated; or in the case of the subduction interface, the fluids have migrated away or reached a less volatile
I don't know if that is how it really works, but that is how I wrap my head around it.
edit on 9/23/2012 by Olivine because: rewriting
edit on 9/23/2012 by Olivine because: (no reason given)