Vibrations from a major earthquake in rural Virginia rattled residents across much of the Eastern United States today, prompting evacuations of many buildings in Washington DC, New York and Boston. Ivan Semeniuk, from Nature’s Washington DC bureau, snapped this image of evacuees on Pennsylvania Avenue, within sight of the Capitol building.
The US Geological Survey pegged the quake size at a magnitude 5.9, which would make this shock one of the biggest in Virginia’s recorded history. A quake of about the same size occurred in the state in 1897. Today’s quake struck at 1:51 (EDT) and reverberated up the east coast, momentarily interrupting a busy working day in some of the most densely populated cities in North America.
Major earthquakes in the eastern United States are rare because the crust is old and mostly stable. But when quakes do occur, the strong crustal rock transmits the seismic waves with relatively little loss of energy, so they can race across vast distances. Initial reports suggested the vibrations were felt at least as far as New Hampshire, some 500 miles away.
The south-eastern United States has been hit by devastating quakes in the past. In 1886, an earthquake estimated at magnitude 7.3 killed 60 people in Charleston South, Carolina. And 200 years ago, a series of three very large quakes struck the sparsely populated area around New Madrid, Missouri. The quakes were so strong they woke people up in Washington DC and New York City.
UPDATE: In the video below, you can see how seismometers from the EarthScope project Transportable Array measured the up-and-down motion of the ground. You can see the waves move across the country – red is upward motion; blue down.