Scientists say there is no link between a controversial natural gas drilling technique and the Virginia earthquake that rattled the East Coast in August.
“Let’s be very clear: fracking did not cause the Virginia earthquake,” said Christopher “Chuck” Bailey, professor and chairman of the geology department at the College of William & Mary in Williamsburg.
Fracking, a short-hand term for hydraulic fracturing, typically involves injecting millions of gallons of water, sand and chemicals underground to break apart rock that contains natural gas. The practice has been linked to minor quakes in Oklahoma and Great Britain.
Energy companies are fracking wells in the Marcellus Shale, a gas-rich rock formation that stretches from upstate New York to the Blue Ridge Mountains. While active in Pennsylvania and West Virginia, they are not drilling Marcellus Shale in Virginia.
The nearest active Marcellus wells to the quake’s epicenter in Mineral — about 45 miles northwest of Richmond — are roughly 100 miles away in West Virginia. Bailey and other scientists said those wells could not have induced the 5.8 magnitude temblor.
“It’s impossible,” said David Spears, a geologist with the Virginia Department of Mines, Minerals and Energy. “The kinds of pressure required to cause something like that can’t be transmitted over those distances from fracking.”
The power surge from a typical gas frack is small even compared to minor quakes, Spears said. Additionally, there are several fault lines separating West Virginia and Mineral that would prevent the spread of underground tremors, he said.
While uncommon, earthquakes occur in Virginia. The most powerful recorded was a 5.9 quake in 1897 in Giles County, which is located within one of the state’s two historically active quake zones. The other — an oval-shaped 40-mile swath between Richmond and Charlottesville — includes Mineral.
The shifting of fault lines 2.5 to 3 miles underneath Mineral caused the quake, Bailey said. The temblor sent waves pulsating through the ground at nearly 4 miles per second. It toppled buildings in Louisa County and damaged structures as far away as the Washington Monument in the District of Columbia.
The underground dumping of fracking fluid — toxic wastewater left over after the gas is extracted — also has been linked to quakes.
In Ohio, which accepts wastewater from Pennsylvania drillers, Gov. John Kasich closed disposal wells suspected of leading to a 4.0 quake in Youngstown on Dec. 31. In Arkansas, home to the Fayetteville Shale reserve, officials took similar action in July after hundreds of minor quakes occurred near a disposal well.
Energy companies say that treating wastewater is too expensive so they pump it deep underground. It causes pressure, occasionally in earthquake prone areas, that is linked to seismic activity.
“They’re essentially lubricating ancient faults,” said John Filson, chief of earthquake studies at the U.S. Geological Survey.
None of the eight disposal wells in southwestern Virginia accept out-of-state fracking fluid, said Rick Cooper, acting chief of the gas and oil division of the state Department of Mines, Minerals and Energy.
While better known for coal production, the region has produced gas since 1931. Some is obtained from fracking but the technique is different from what’s happening in Pennsylvania and West Virginia, Cooper said.
Fracking in Virginia
Drillers fracking in Virginia rely mostly on nitrogen — not water — to force gas to the surface, he said. There is some wastewater, but significantly less than what comes out of a typical Marcellus well, he said.
Virginia drillers are allowed to pump wastewater into disposal wells, Cooper said, but there is no evidence that it has led to an increase in seismic activity. Also, he said it could not have migrated to the fault that caused the Mineral quake.
Gov. Bob McDonnell, who is trying to make Virginia the “energy capital of the East Coast,” supports all types of fracking for natural gas. At least one company has leased land in Rockingham County to tap into the Marcellus Shale reserve.
But Rockingham leaders, worried that fracking could lead to groundwater contamination, have not approved the project. Their concern appeared validated last month after the U.S. Environmental Protection Agency said for the first time that fracking may have caused water pollution in Wyoming.
The draft finding could have significant implications as states weigh whether to allow fracking in shale reserves and utility companies move away from coal-fired power plants in favor of natural gas plants.
Dominion Virginia Power, a subsidiary of Richmond-based Dominion Resources, has built several gas plants in recent years. It also plans to convert a handful of coal plants to natural gas.