Monumental earthquakes in Haiti and Chili make me wonder....Are we safe in central Virginia

As one who has experienced an 8.9 shaker in Shemya Alaska in 1965, I am acutely aware of the pure horror one experiences when terra firma turns to jelly. So I wondered, are we safe here in the Charlottesville area? The short answer is yes. Though we are in a seismically active zone, quakes here are relatively frequent, but generally small. The central Virginia Seismic Zone is a region of persistent seismic activity in the Piedmont province covering approximately 3,000 mi². As recently as 12/09/2009 at 3:59 PM about thirty miles west of Richmond there was a 4.5 Mag. quake. It was at a depth of about 3 miles. It was preceded by a magnitude 3.8 event on May 5, 2003. The largest Virginia earthquake in recorded history occurred on May 31, 1897 in Giles County and is estimated to have had a magnitude of 5.8.

A little on the Ricter scale for determining the strength of a quake. It is a base-10 logarithmic scale obtained by calculating the logarithm of the combined horizontal amplitude of the largest displacement from zero on a Wood–Anderson torsion seismometer output. So, for example, where an earthquake one whole number greater has 10 times the amplitude and has approximately 31.6 times more energy. For example, M7.0 has about 31.6 times the energy of M6.0, and 1000 (which is to say 31.6²) times the energy of M5.0. More pointedly, the quake in Chile measuring 8.8 was 800 times as powerful as the one in Haiti. However, the quake in Haiti was only a few miles from the surface and Chile's was about twenty miles from the surface.