A freight train? Thunder? �Holy cow ... earthquake!�

MSNBC (Link) (July 16, 2010)

The largest earthquake ever recorded near the capital rattled Washington, D.C., early Friday, waking many residents but causing no reported damage.

The quake hit at 5:04 a.m. ET with a magnitude of 3.6, according to the U.S. Geological Survey. It was centered near Rockville, Md., the USGS said.

NBC News reported that the quake was felt in the D.C.-area, Maryland, Virginia, West Virginia and Pennsylvania.

Amy Vaughn, a spokeswoman for USGS, told NBC station WRC that the quake was the largest recorded within 50 kilometers (31 miles) of Washington since a database was created in 1974.

The previous record within that time period was a 2.6 magnitude temblor in 1990.

�So this is pretty significant for your area,� Vaughn told WRC-TV.

The area�s last quake � with a magnitude of 2.0 � occurred in May 2008.

Gloria Jackson, a police communications supervisor for the Montgomery County Police Department, said the department has received numerous calls about the earthquake.

However, there were no reports of any damage or injuries.

�Thunder�

Debby Taylor Busse said she was in the basement of her home in Vienna, Va., when she felt the quake hit. She was already awake watching television, but her husband had been asleep in a second-floor bedroom when the tremor woke him.

�I didn�t know what it was,� Busse said. �I have never been in an earthquake before. It felt like an airplane going overhead or thunder, but it wasn�t coming from above.�

�I heard a sustained rumbling, like the sound of thunder or a low-flying helicopter,� Nancy Kochli, of Culpeper County, Va., told WRC-TV. �I did not feel it at our home, but I distinctly heard it. It was loud enough to wake me from the half-sleep right before my alarm went off.�

NBC News correspondent Jim Miklaszewski said he felt the quake for about 10 seconds at his Maryland home, which is located about 25 miles north of the capital.

�It started as a low audible rumble that built to a crescendo and shook the house and rattled the windows,� he added.

NBC News colleague Tom Costello told TODAY that the quake reminded him of a �massive freight train� passing nearby.

Thousands of messages were posted to social networking website Twitter following the quake, with many people expressing surprise but not reporting any adverse effects.

One Twitter user, @olli85olli, wrote: �Holy cow ... earthquake! 3.7 on the Richter scale. Nothing in comparison to others, but this is new for us in Maryland/VA.�

However another, @stevebuttry, wrote: �Quake didn�t disturb any of the tiny items in @mimijohnson�s shadow box, which can fall if you slam the door. Not that I ever do that.�

Aftershocks possible

The USGS said it was possible that �smaller aftershocks� might hit the area. USGS geophysicist Jessica Sigala told WRC-TV: �But they should die out in a few days.�

Sigala said the incident would help experts to discover the fault lines in the D.C. area.

�We all know the San Andres fault by name,� she said. �But over here, they don�t happen very often. So this one will help us (find the fault lines).�

The USGS said there had never been an earthquake centered within the District of Columbia itself.

However, ground vibrations from earthquakes far away have been felt by D.C. residents before.

A quake which did considerable damage to Guadeloupe, West Indies, in 1843 was felt in the eastern United States, including D.C., according to USGS information.

The earliest shock that may have affected some sections of Washington occurred on April 24, 1758, the USGS said. Its probable center was near Annapolis, Md., and it was felt into Pennsylvania.

A sequence of great earthquakes occurred in the Mississippi Embayment in 1811 and 1812, which were noticed by people over an area of 2 million square miles, including D.C., where people were �badly frightened,� according to records.

First lady �much alarmed�

And a quake in March 1828 was felt over a wide area including seven eastern states and D.C., according to the USGS.

John Quincy Adams, then president of the United States, left the following account in his diary: �There was this evening the shock of an earthquake, the first which I ever distinctly noticed at the moment when it happened.�

�I was writing in this book, when the table began to shake under my hand and the floor under my feet. The window shutters rattled as if shaken by the wind, and there was a momentary sensation as of the heaving of a ship on the waves.�

�It continued about two minutes, then ceased. It was about eleven at night. I immediately left writing, and went to my bedchamber, where my wife was in bed, much alarmed.�