Experts: Chances for local aftershocks from Tuesday's quake are slim

Area experienced little structural damage

August 24, 2011|By KATE S. ALEXANDER |
  • Bricks fell from a chimney to the sidewalk along Washington Street at West Side Avenue Tuesday. Effects of an earthquake in central Virginia are believed to have toppled the chimney at the West Side Avenue residence.
By Kevin G. Gilbert/Staff Photographer

Vibrations from Tuesday’s earthquake in central Virginia were felt along the East Coast thanks to the “old and cold” geology of the region, an expert said Wednesday.

Gavin Hayes, a research seismologist with the U.S. Geological Survey in Golden, Colo., said the geology of the region allowed Tuesday’s temblor to transmit over greater distances than have earthquakes of similar magnitude in other parts of the nation.

However, the chances of Washington County feeling aftershocks from the 5.8-magnitude earthquake centered 123 miles south in Louisa County, Va., are slim because the USGS expects those to only be felt near the epicenter, he said.

Multiple aftershocks have been registered since the initial earthquake, Hayes said, the largest of which was a magnitude 4.2.

Aftershocks — which are normal quakes that occur as the earth works back to equilibrium after an initial event — are generally less intense, he said. They are expected to continue at the epicenter for the next few days and weeks.

In the wake of Tuesday’s quake, the USGS has begun to study the region to better understand its stresses, fault lines and energy, Hayes said.

Large earthquakes are infrequent and generally unexpected on the East Coast.

The largest temblor to shake Virginia was a magnitude 5.9 near Blacksburg in 1897, Hayes said.

Only three earthquakes were listed in Virginia’s history, according to the USGS website,

Maryland and West Virginia each only had one recorded earthquake, while three were recorded in Pennsylvania, according to the site.

Brunswick water affected

In the hour after the earthquake happened at 1:51 p.m., Washington County’s emergency dispatch center received more than 130 calls to 911 and 278 total calls for service, said Kevin L. Lewis, director of Washington County Emergency Services.

Although there were no serious problems reported in the Tri-State area as a result of Tuesday’s earthquake, the area was not entirely unscathed.

Users of Yourtee Spring water in Washington County near the Frederick County line were warned by officials in nearby Brunswick, Md., to halt consumption of the water.

About 10 to 15 households on Boteler, Rohrersville, Weverton and Yourtee roads were notified that the earthquake “has affected the quality of the water that flows naturally from Yourtee Spring,” Brunswick City Administrator Rick Weldon said.

“It (looked) like water from the Potomac River,” Weldon said Wednesday.

By late Wednesday morning the condition had improved to the point that people could drink the water after boiling it, he said.

The city also arranged to have fresh water available to residents through a tanker in the parking lot of Himes Country Store at 1325 Weverton Road in Knoxville.

“We will continue to provide this service until we can confirm that all users have unrestricted access to potable water,” Weldon wrote in a letter to Verna Brown,  Washington County emergency management coordinator.

The water will be available at no cost to users of the Brunswick water system served by Yourtee Springs until the spring can be reactivated, according to an official notice from the city. Personnel will be on hand to assist with filling container between 7 a.m. and 7 p.m., Weldon said in an email.

Pleasant Valley Elementary School also was affected by the Brunswick water system problems, but the school had a sufficient supply of water from a 10,000-gallon storage tank, Weldon said.

The turbidity level of the water, or the amount of sediment in the water, started to drop dramatically starting at 2 a.m. Wednesday, Weldon said.  

The city of Brunswick serves about 2,200 water customers, Weldon said.

Little structural damage

Damage-assessment teams were assembled immediately after the earthquake and deployed to all major Washington County facilities, but no damage was found, county Public Works Director Joseph Kroboth III said.

Minor damage was found at the Clear Spring High School building, which is not county-owned, Kroboth said. Some pre-existing cracks in the walls were enlarged, and a non-load-bearing partition wall was displaced by about 2 or 3 inches, he said.

“A determination was made between the board of education and the building inspectors on the scene that the building was safe and suitable for the opening of school,” Kroboth said.

The Clear Spring water system was also found to have an increase in turbidity, but that cleared up by Wednesday morning, Kroboth said.

The city of Hagerstown reported no injuries or significant property damage as a result of the earthquake.

Mary King, city communications manager, said in a news release Tuesday that the city’s fire department responded to a call for a fallen chimney on West Side Avenue and Washington Street.

City inspectors determined that the earthquake was likely to blame for the chimney collapsing, which was older structure, she said Wednesday.  

No utility or public safety disruptions were experienced in the city as a result of the quake.  

Staff Writers Heather Keels and Dan Dearth and mobile journalist Caleb Calhoun contributed to this story.

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