Virginia Earthquake of 2011, Aug 23

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Discussion Overview

The discussion revolves around the 5.8 magnitude earthquake that occurred in Virginia on August 23, 2011. Participants share their experiences of feeling the quake across various locations, discuss its geological context, and reference historical earthquakes in the region.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Historical

Main Points Raised

  • Some participants note the earthquake's magnitude varied in reports, initially stated as 5.8, then 5.9, and later reverted to 5.8.
  • Several individuals describe their personal experiences of feeling the quake, with varying intensities and durations reported.
  • Some participants express surprise at the earthquake's occurrence, citing the relative inactivity of the Appalachian region in terms of seismic activity.
  • There are mentions of historical earthquakes in Virginia, including a significant event in 1897, and discussions about the geological history of the area.
  • Some participants report discrepancies in USGS data regarding the earthquake, indicating different sources may have reported varying details.
  • Several participants discuss the impact of the quake, including reports of shattered windows and concerns about potential damage in various locations.
  • There is a reference to other recent seismic events, including an earthquake in Colorado, which some participants connect to the discussion.

Areas of Agreement / Disagreement

Participants generally share their experiences and observations, but there is no consensus on the specifics of the earthquake's effects or the accuracy of the reports. Multiple competing views and uncertainties remain regarding the magnitude and impact of the quake.

Contextual Notes

Participants mention limitations in the available data from USGS and the potential for discrepancies in reported magnitudes and effects. There is also a lack of clarity regarding the historical context of seismic activity in Virginia.

Who May Find This Useful

This discussion may be of interest to those studying geology, seismology, or individuals curious about regional seismic activity and historical earthquakes.

  • #61
Astronuc said:
Code: 
          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.
 
Last edited:
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  • #62
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
 

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