Virginia Earthquake of 2011, Aug 23

[Evo]

          UTC DATE-TIME       LAT      LON     DEPTH    Location
Mag       y/m/d     h:m:s     deg      deg       km  
5.8   2011/08/23 17:51:04    37.936  -77.933    6.0    8 km ( 5 mi) SSW of Mineral, VA   
2.8   2011/08/23 18:46:50    37.931  -77.935    0.1    9 km ( 5 mi) SSW of Mineral, VA   
2.2   2011/08/23 19:20:26    37.911  -78.004    0.1   13 km ( 8 mi) S of Louisa, VA   

4.2   2011/08/24 00:04:36    37.912  -77.951    7.9   11 km ( 7 mi) SSW of Mineral, VA 
3.4   2011/08/24 04:45:26    37.925  -77.994    4.9   11 km ( 7 mi) S of Louisa, VA 

2.5   2011/08/25 04:06:47    37.923  -77.988    0.1   11 km ( 7 mi) S of Louisa, VA 
4.5   2011/08/25 05:07:50    37.940  -77.896    5.0    7 km ( 5 mi) S of Mineral, VA 
2.3   2011/08/25 06:37:31    37.912  -77.969    0.1   12 km ( 7 mi) SSW of Mineral, VA 
2.4   2011/08/25 15:27:47    37.951  -77.924    0.1    6 km ( 4 mi) S of Mineral, VA

17:51:04 UTC = 01:51 PM EDT

This is interesting, not only since it was about 8-9 miles from a nuclear plant, or that the magnitude of the initial event was within about 0.2 to 0.3 mag of the DBE of the NPP, but they have having a little swarm - and this is an area that doesn't normally get 4s and 5s.

In the NE, there's been a few more tremors.

It bears watching, because something has changed.

I thought it was normal for any earthquake to have aftershocks for months.

Scientists are actually surprised at the low number of aftershocks.

"Low" number of Va. earthquake aftershocks felt

For the size earthquake that occurred, I think the number of aftershocks so far has been remarkably low," said Amy Vaughan, a geophysicist with the USGS Earthquake Information Center in Colorado. "I don't know if that's an indication of things to come or not. ... There's likely there will be some more, but I don't know for how long and how large."

http://www.cbsnews.com/stories/2011/08/24/national/main20096620.shtml

It would be bad it this turns out to be a foreshock and a larger earthquake is yet to come.

 

[Astronuc]

Given a 5.8 mag, the aftershocks are not surprising. There are usually some aftershocks.

Of interest is - what has changed that initiated the 5.8 mag in an area that rarely gets those kind of quakes.

We see small quakes - on the order of 2s or 3s - and these are usally isolated. We could have a 4, but that would be unusual.
Recent earthquakes in NE US - http://www.ldeo.columbia.edu/cgi-bin/quake.cgi