When Was the Last Earthquake Near Washington, D.C.?

Remy Melina

Date: 16 July 2010 Time: 06:10 AM ET

The mild, 3.6-magnitude earthquake that rattled Washington, D.C., and the surrounding area at 5:04 a.m. local time was the largest earthquake to strike near the nation's capital since 1984. On April 23 of that year, a 4.4-magnitude quake struck near Wicomico Church, Va., about 120 miles (193 km) north of D.C., according to the U.S. Geological Survey.

Before today, the most recent earthquake to strike in the D.C. area was a minor, 1.8-magnitude quake that struck on May 6, 2008 in Annandale, Va., which is 13 miles (21 km) west-southwest of the district, according to the USGS. Like today's earthquake, it was just large enough to be felt, but not large enough to cause damage.

Today's earthquake was felt by thousands, and was centered in Montgomery County, about 20 miles (32 km) northwest of the capital.

The Northeast rarely experiences extreme earthquakes, especially compared with the West Coast, because the Northeast is not near any plate boundary, said USGS geophysicist Paul Caruso. The closest plate boundary, where two tectonic plates meet up, is the Atlantic spreading center, located in the middle of the Atlantic Ocean, Caruso said.

However, scientists have warned that the Northeast is more prone to earthquakes than previously thought, according to a 2008 study, with researchers estimating that quakes with a magnitude of at least 5.0 should be expected, on average, about every 100 years.

Though today's temblor is the largest one to have occurred since 1984, the largest recorded earthquake ever to strike in the area, a magnitude 5.6, occurred more than 100 years ago on May 31, 1897, in Giles County, Va. When an earthquake reaches a magnitude of 5.5 or higher it can theoretically cause a significant amount of damage, according to Caruso.

Within two hours of this morning's temblor, more than 6,700 people had reported the quake on the USGS's "Did You Feel It?" website, which tracks earthquake activity as it is reported by the public. People reported feeling the rumble all across Maryland, in Washington, and in states including West Virginia, Virginia and Delaware.

"It was a very small earthquake," Caruso told Life's Little Mysteries. "The worst damage it caused is probably some cracked sidewalks – nothing significant."

This article was provided by LifesLittleMysteries, a sister site to LiveScience.