A small earthquake struck the D.C. area Tuesday afternoon, the U.S. Geological Survey says. The earthquake measured 1.8 on the Richter scale and the epicenter was 1 mile west-southwest of Annandale (38.828°N, 77.234°W), the U.S. Geological Survey says. The U.S. Geological Survey says the quake struck at 1:30 p.m. About four miles NW of my office, ten miles west of the Pentagon. I heard a boom, no shaking.
Earthquakes with a magnitude of about 2.0 or less are usually called microearthquakes, and about 1,000 occur around the world each day, says Bruce Presgrave, a geophysicist with the U.S. Geological Survey National Earthquake Information Center in Golden, Colo. U.S. Geological Survey spokesman Bill Leith says it is not uncommon for a D.C. area earthquake to be felt 15 to 20 miles away from the epicenter. In California, a 1.8 magnitude earthquake may not be felt at all, Leith says.