Is Another DC Earthquake Coming?

Scientists have uncovered the cause of the 2011 Virginia earthquake that shook the Nation's Capital, and have made an ominous discovery along with it: the possibility that it could strike again.

It was quite the shock when the 5.8 magnitude earthquake struck a town in central Virginia on Aug. 23, 2011 and reverberated up the coast, rocking the D.C. area and causing a region-wide panic as people flooded out of buildings and into the streets. Now, a new study published in the Journal of Geophysical Research - Solid Earth indicates that pieces of the mantle have been breaking off below the North American Plate, and the region is sinking into the earth -- meaning we could get another earthquake at some point.

Earthquakes are extremely rare in the eastern United States since we aren't near a fault line, which is an area where two tectonic plates rub against each other. The existence of earthquakes smack dab in the middle of a tectonic plate has baffled scientists, and so the researchers wanted to look deeper into this particular quake.

The huge plate that Virginia sits on covers much of North America and a good chunk of the Atlantic and Greenland. The research team that published the paper wanted to better understand what is happening with this plate, and used seismic waves generated by earthquakes hundreds and even thousands of miles away to create a 3D map of the area, according to a statement accompanying the paper.

What they found was an uneven plate thickness, and a mix of old and new rock, which could explain why it's so unstable. Sometimes, dense parts break off from the plate and sink into the warm "asthenosphere" below the plate. The asthenosphere, which is lighter, surges into the void and turns into new rock. This causes old fault lines to become active again, resulting in earthquakes.

As a result, these seismic zones are likely to remain active, and we'll probably see another earthquake in the future -- when, however, remains a mystery.

Image via Wikimedia