A few minor points on the Virginia earthquake

I had not initially intended to do a post on yesterday’s earthquake in Virginia, mostly because there are a lot of structural geologists and seismologists that can do a much better job of describing this event than I can. For an excellent summary of the geology of the earthquake, check out Callan Bentley’s blog Mountain Beltway.

I do have to add  this outstanding animation of the seismic waves from the earthquake arriving at various seismographs across the U. S., courtesy of Bad Astronomy and paleoseismicity.org:

I can say that, while there was apparent damage at the Washington Monument, the museum was largely unaffected. While we did get several seconds of substantial vibration, the only obvious thing that happened here was that the air extraction pipes that hang from the ceiling in my lab sagged to their fully extended positions.

Beyond the cool factor, I do have a real interest in events like this, because it has a potential tie-in to my own research. Here’s a map of the earthquake area (from Chuck Bailey) showing some of the known faults in the area; I’ve added the location of Carmel Church to this map:

While Carmel Church wasn’t sitting on top of this fault, it does sit in the middle of the Hylas Fault Zone, which has also produced earthquakes. There is ample evidence of Cenozoic sediments being affected by movement along basement faults (for example, Berquist and Bailey, 1999, or this abstract from last year’s southeastern GSA meeting). I’ve suspected for some time that reverse fault motions along the Hylas Fault Zone could be responsible for some of the unusual geology we see at Carmel Church (and, yes, I’m going to leave that as a teaser), so yesterday’s earthquake was a dramatic confirmation of the occurrence of these types of events.

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