News Release |
U.S. Department of the Interior January 7, 2005 |
|
The seismic waves generated by the Sumatra-Andaman
Islands Earthquake caused the water level in a well in Christiansburg, Va., to
oscillate nearly 3 feet (see below). The epicenter for this earthquake was
9,600 miles away from the well; seismic waves travel through the Earth at
about 7,400 miles per hour. The water-level oscillations started about an hour
after the earthquake and were slowly dampened out over a 5-hour period. This
well is 450 feet deep, finished in limestone of the Beekmantown Formation, and
water enters the well via fractures or cracks in the rock. Compression and
expansion of these fractures by seismic waves cause the water to be drawn in
and out of the well, similar to the way bellows work.
Earthquake effects have frequently been detected in this well since the Virginia Department of Environmental Quality (VADEQ) began monitoring the well in 1969, according to David Nelms, ground-water specialist for the U.S. Geological Survey (USGS) in Virginia. "This is the first time that the effect of an earthquake has been recorded and available online in near real-time," he said. Recent appropriations in the Commonwealth’s
budget, and funding provided by the Interstate Commission on the Potomac River
Basin, in response to the recent drought, has expanded the real-time
ground-water monitoring network across Virginia. This monitoring is part of a
cooperative program between VADEQ and the USGS, which measures 280 wells
statewide. Real-time water levels can be viewed at http://va.water.usgs.gov/ *
* * USGS * * *
|
|
Contact: GS-W-VArmd_webmaster@usgs.gov
U.S. Department of Interior,
U.S. Geological Survey
Privacy Statement
Disclaimer
URL://va.water.usgs.gov/NEWS_RELEASE/quake_dec26_2004.html Last modified: 01/19/05 12:45:08 PM