Signs of the Times - Virginia Earthquake 2003

December 2003

Seen Around Town: Virginia Earthquake 2003

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That seismic boom you felt today in Charlottesville (December 9, 2003) at 3:59 p.m. EST was not Gore's endorsement of Dean but rather a light earthquake of 4.5 magnitude 28 miles west of Richmond (37.6 degrees North, 77.9 degrees West): zip code 23063 in Goochland. Its depth was 5 km (3 miles) (USGS, December 9, 2003)

NEIC/USGS Bulletin

Minor damage has been reported in Nelson County, Virginia and the earthquake has been felt in Virginia, Washington, D.C. and areas of Maryland bordering on Washington, D.C., as well as in Raleigh, North Carolina.

"The above figure, from the 9 December event, [indicates] that there are two sets of P-wave and S-wave arrivals. The P-wave and S-wave arrivals for the first event are at a little before 59 seconds and 88 seconds respectively, and those for the second event are about 12 seconds later for each arrival. Based on the relative amplitudes, the two events have the same magnitude to within 0.1 magnitude units.

The ground shaking which people feel comes from the S-wave arrivals. Many of the felt reports reported a duration of up to 30 seconds. If this were from a normal event (one with only a single set of arrivals), one would infer from this that the magnitude was larger than 4.5. Based on these records, we think that what the observers actually experienced was shaking from the two separate events. A few observers at more distant locations (Waynesboro and Blacksburg) report feeling two successive "bumps" with about a ten-second time separation." (VTSO, December 2003)

"Kevin McCleary, 26, a systems engineer in Tysons Corner, said he experienced a rumble that he likened to a heavy desk being dragged across the floor. "After 40 seconds of that, I realized it was not furniture-related," he said. Then he called police.

"I hope you don't think I'm crazy, but I think we had an earthquake," he said he told a police dispatcher. "I thought we were crazy," he said the dispatcher replied.

"I didn't know we got earthquakes here," McCleary said.

" Slight damage (VI)at Bremo Bluff and Kents Store. Felt (V) at Columbia, Fork Union, Goochland, Oilville, Rockville andSandy Hook; (IV) at Appomattox, Amelia Court House, Amherst, Blackstone, Bumpass, Charlottesville,Chester, Chesterfield, Colonial Heights, Cumberland, Dillwyn, Farmville, Glen Allen, Lawrenceville,Louisa, Manakin Sabot, Mechanicsville, Midlothian, Mineral, Palmyra, Petersburg, Powhatan, Richmond,Scottsville and Spotsylvania; (III) at Alexandria, Fairfax, Falls Church, Fredericksburg, Lexington,Lynchburg, McLean, Roanoke, Staunton and Vienna. Also felt (III) at Bethesda, Rockville and SilverSpring, Maryland and at Rocky Mount and Winston Salem, North Carolina. Felt (II) at Chapel Hill,Greensboro and Raleigh, North Carolina and at Washington, DC. Felt in much of Maryland and Virginia.Also felt in north-central North Carolina and a few areas of Delaware, New Jersey, New York,Pennsylvania and West Virginia." (VTSO, December 12, 2003)

In Charlottesville, Va., Larry J. Sabato, a University of Virginia political scientist, told interviewers on NBC4-TV, "It shook my house pretty violently. I lost some glassware and pieces of china. I've been here in Charlottesville 33 years and never felt another earthquake."" (William Branigin, The Washington Post, December 9, 2003)

"We just had some new equipment installed today in Pavilion IV, plus this Pavilion has all the University's pipes running through it deep down below. I was working on the third floor, and I was convinced the equipment/pipes/boiler had exploded. The rumble was deep and forbidding! I ran out to the Lawn and found many students gathered outside wondering what had happened, too. If that was a 4.5, I never, ever want to experience a 6 or 7!" (Larry Sabato, electronic mail, December 9, 2003)

Ginger Greene says, "Interesting that they would rush to ask Larry Sabato, instead of a local meteorologist. Maybe it was the Gore/Dean endorsement after all." (electronic mail, December 9, 2003).

Barnie Day explains, "What set it off was that poll indicating that a clear majority of Virginians support Governor Warner's tax reform plan." (electronic mail, December 10, 2003).

Virginia Tech Seismological Observatory, December 9, 2003

For more information, call 540-2316521 or 303-273-8500.

Virginia has had over 160 earthquakes ince 1977 of which 16% were felt. This equates to an average of one earthquake occurring every month with two felt each year.

"On May 5, 2003, A minor earthquake, preliminary magnitude 3.9 according to the U.S. Geological Survey, occurred in central Virginia at 12:32 p.m on May 5, 2003. The epicenter was about 30 miles southeast of Charlottesville [near the town of Columbia], about 35 miles north-northeast of Farmville, and about 35 miles west-northwest of Richmond." (USGS Release, May 5, 2003)

"The September 22, 2001 Charlottesville earthquake was notable for its shallow focal depth and location: it probably occurred within the eastern city limits. Most residents on the eastern side of town both felt and heard the shock, and many called the local officals.Initially, the sheriff's department reported that the cause of the event was unknown, but possibly a sonic boom. The author was able to confirm the fact that the event was an earthquake, and distributed that information to the local authorities, press and public. (Cooperative Central and Southeastern US Integrated Seismic Network - VPI & SU Grant Award No. 01HQA, Annual Project Summary, November 1, 2001)

See also accounts by Diane Taylor and Downing Smith (with annotation on the earthquake of 1897) and comments by Rey Barry and Jim Peterson.

Comments? Questions? Write me at george@loper.org.