Well being the skeptic that I am, when I saw the "pay to read more" nonsense on that site I knew that had to be like one of those, "pay us for the free stuff the government gives out but we aren't telling you that part".
The USGS and the Pacific Geoscience Center would hardly be publishing a copyrighted pay per view earthquake report. And they indeed aren't.
It's fascinating stuff. I've been reading about the monitoring around here for years and this is typical but still intriguing stuff.
SCIENTISTS MONITOR A PREDICTED EPISODE OF DEEP FAULT SLIP DEEP BENEATH VANCOUVER ISLAND AND PUGET SOUNDFeb 1,07
Quote:
A forecast episode of the phenomena called "Episodic Tremor and Slip" (ETS) has begun on the Cascadia subduction zone....
Present understanding of ETS suggests slow slip of several centimetres is happening on the deeper portion of the Cascadia subduction fault at depths of 25 to 45 kilometres This slip causes a small change in stress which triggers the tremor activity. Each event adds stress to the upper locked portion of the subduction thrust fault, bringing it closer to failure. Further research is required to determine whether these very small stress increments play a significant role in triggering giant megathrust earthquakes.
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Further reading
I imagine it will be like Mt St Helens. Not having monitored the slip so closely before we won't realize how obviously ominous 10 feet of ground swell per day is until the
blast big slip.
"The catastrophic eruption on May 18, 1980, was preceded by 2 months of intense activity that included more than 10,000 earthquakes, hundreds of small phreatic (steam-blast) explosions, and the outward growth of the volcano's entire north flank by more than 80 meters."
You kind of think with that much ground swell they wouldn't have had a person stay on the top for more than the brief time it took to take necessary measurements. But they hadn't monitored an explosive volcano so closely before.
I liken the ground movement around here to a sort of breathing like movement. The Olympic Peninsula will bulge upwards, slowly slip and sink back down in 18 month cycles. All the while the upper sliding puts more and more tension on the locked portion deeper down. I just hope when the big one is close, something will be different enough we get some warning.