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Re: Quakes Shift Whole Island Of Sumatra...
Sorry about the off subject comment on the DML list.
The USGS site is...
http://earthquake.usgs.gov/recenteqsww/Quakes/usslav.htm Which has
more data than any of us could possibly process. Having said that....
Just a standard "Ring of Fire" megathrust event really. The earthquake
occurred at a spot where the Indian Ocean plate is gradually being
forced underneath Sumatra, which is part of the Sundra/Eurasian plate,
at about twice the speed a human fingernail grows. This area is a
quadruple plate boundary area and under intense oblique convergence
The quake was 6 miles under the ocean floor. The resulting bulge on
the sea floor could be as high as 30 feet and is probably a hundred or
more miles long for an earthquake this big. It really displaced a huge
amount of water (several meters of uplift) so it is amazing to me that
it didn't kill more than has been reported. I am equally amazed that
the west coast of Australia didn't get hit by the "ripples". Some of
the aftershocks could easily set off more waves too. I hear a lot of
misinformation in the news media though. The waves did not hit the
shore at the speed of an airliner. The wave front slowed considerably
by the shallowing effect of the shore which is why the rear of the wave
catches up and rises up so high. The speed at which the wave hits the
shore in Thailand looked about the same speed as the really scared
people running ahead of it or maybe slightly faster. The waves travel
as a long wavelength low amplitude phenomena very quickly across the
open ocean though.
The region is in deep do do as it is wet season to begin with, they
were reeling from terrorist attacks and the resultant drop in tourism
any way, and they will now suffer from massive epidemics of disease due
to lack of sanitary water supplies. Let's hope that our government
takes notice and increases vigilance of the Atlantic basin to the level
that they watch the Pacific. As big as this one was, it was relatively
small compared to the 1960 Chile quake (9.5) and the 1964 Alaska quake
(9.2). I live as far from the ocean as you can get on the North
American Plate for a reason! Now if Yellowstone just doesn't blow up in
(70 miles from the geographic center of the continent)