August 23, 2011 by Chuck Bailey
This afternoon, our Geology faculty meeting was adjourned by a motion from the floor. A 20-second motion from the floor, but more to the point, a 20-second motion from the Earth. Virginia and the East Coast experienced a moderate, but widely felt earthquake at 1:51 p.m. (local time). It was quite a jolt.
The earthquake’s epicenter was about 60 km (~40 miles) northwest of Richmond, Virginia and occurred in the central Virginia seismic zone- an area of modest (or so we thought), but persistent seismic activity in the Piedmont. This region is laced with ancient faults that formed 200 to 300 million years ago when Virginia was at the frontline in an ugly collision between tectonic plates. I study these fault zones. Today’s temblor makes it clear that these faults are 1) not inactive and 2) have the potential to produce significant and damaging earthquakes. We have much to learn about the stresses that cause faults to slip this far from modern tectonic plate boundaries (in this case at the Mid-Atlantic Ridge some 3,000 km from central Virginia) and the hazards that these old, but restless, faults pose. It’s why we do research at William & Mary.
An earthquake presaging a hurricane- this could be quite a semester to study the Earth!