[Scan-DC] EXTERNAL: EARTHQUAKE

[Hoyden, Sean R (N-The SI)]

http://www.washingtonpost.com/blogs/capital-weather-gang/post/alert-earthquake-rocks-central-virginia-dc-region/2011/08/23/gIQAMwvEZJ_blog.html

Minutes after the quake, the director of the U.S. Geological Survey, Marcia McNutt -- who watched objects falling from the shelves in her office -- cautioned that the shaking might not be over.

"What the concern is, of course, is that this is a foreshock. If it's a foreshock, then the worse is yet to come."

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The USGS director mentioned here was quoted as inferring that this may have only been a "fore-shock"... is that just sensationalizing at its finest, or is there legitimate concern here?

Sean


-----Original Message-----
From: scan-dc-bounces at mailman.qth.net [mailto:scan-dc-bounces at mailman.qth.net] On Behalf Of johnson at cpcug.org
Sent: Tuesday, August 23, 2011 3:05 PM
To: scan-dc at mailman.qth.net
Subject: EXTERNAL: [Scan-DC] EARTHQUAKE

all -

The tensor solutions from the quake indicated a a thrust, or reverse,
fault with a North by Northeast strike, close to the general trend of the
Appalachians.  The solutions also show a slight obliqueness to the rocks'
motion.

In other words the Earth squeezed together a certain amount and shortened
the crust down in the Mineral area.  It was not a purely compressive
because the "beachball" pattern shown on the USGS site shows there was
some oblique slippage to one side.  The USGS site said it was only a half
mile deep, a very shallow depth.

Ralph Johnson



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