Oregon's energy hub on the Willamette River a catastrophic risk when a megaquake hits
Workers at Siltronic Corp. in Northwest Portland have a vision of flaming petroleum surging toward them on the Willamette River as bridges and high-voltage transmission towers topple and gas pipelines rupture.Read more
“Geologist [I'm Climate Change]”
Since: Mar 07
#1 Sep 23, 2013
Looks like a scene stage for a big Hollywood movie.
Got some info on the last one as a result of a search of rebound megathrust quakes around the Pacific rim (currently lost in the woods @ Haida Gwaii).
Last event in 1700AD was a 2 stage event in the North In Washington.
Main runout in 1700 was a WNW. vector which decompressed the entire continental North American plate in a great circle through Oregon, Colorado, New Madrid, Charleston & S. of Bermuda,(with big rift spreading quakes along the great circle in the decades following the event. The continent of N. America appears to have decompressed like a rubber block, with the rift events in the upper crust occurring @ random after 1700.
2nd event in Washington area appears to have struck @ the Cascadia-garibaldi junction & extended to central Vancouver & down to @ least N. Oregon. This one had less runout (mostly the equivalent of an arc ~10-15m total), and appears to have been WSW vector covering the great circle between Yellowstone-Chilcotin hotspots @ the Canadian shield. The quakes in the Canadian Adirondacks-N.Appalachians may be related to decompression from this vector.
There may have also been a NW. runout from N.California via the Gorda arc but this appears unlikely as the 1700 runout appears to have added to the forearc creating an end stop @ Mendocino.
Next quake will either be...
SW. vector directly releasing Juan de Fuca-N.America convergence (~4 to 5cm/yr), been over a thousand years since a quake occurred from this vector. The absence of descending plate compression quakes since 1700 is because the Juan De Fuca plate did not lurch NE in January 1700.
NW.vector with epicentre @ Mendocino & spreading N. through either N.California & Oregon, OR California-Washington with the latter event terminating @ the Cascadia-Garibaldi junction box in the region of Seattle. This is the commonest cause of megathrust quakes in the history of Cascadia & releases overpressure caused by spreading of the Gulf of California rift which is extending toward Yellowstone hotspot via the basin & range moving all of the NW. arm of the developing over the top of the Juan de Fuca plate.
The Mendocino epicentre scenario @ NW vector is the most likely to occur. GPS data however currently either omits California-Juan de fuca convergence or does not register it as a result of all the forearc & arc being backed up. A major thrust quake @ uplift has occurred in the forearc @ Mendocino in the recent past so the area is locked & loaded.
have a nice day: Ag
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