Earthquakes Raise Fracking ConcernsAug 29, 2011 | Parker Waichman LLP
An earthquake in Colorado last week has helped reignite fears that activities associated with hydraulic fracturing, or fracking, could increase seismic activity. The 5.3 magnitude tremblor occurred last Monday southwest of Trinidad in southern Colorado, an area where fracking is being used to tap shallow coal-bed methane gas reserves.
According to the Colorado Independent, the earthquake was considered rare but "consistent with the region and historic activity in the area," so for now, no one is blaming fracking. But a September 2001 swarm of earthquakes in the same area prompted an investigation by U.S. Geological Survey (USGS) that was unable to rule out fracking activity as a possible cause.
There are two ways fracking operations can cause earthquakes. Fracking itself, which involves injecting a cocktail of water, sands and chemicals into the earth at high pressure, can result in small tremblors.
"You're not going to get a really big earthquake," Mark Zoback, a Stanford University geophysics professor who has studied the issue, told the Chronicle "To get a big earthquake, you'd need a really big fault. When these oil fields are being developed, the companies are very aware of where the faults are. They don't want to do something stupid."
Injecting waste into underground fracking disposal pits may cause bigger quakes.
"It's a little bit like an air hockey table," Cliff Frohlich, associate director of the Institute for Geophysics at the University of Texas, Austin, and a member of a team that studied earthquakes in Dallas that occurred near such disposal pits, told the Chronicle. "You pump air into an air hockey table so that when you push something, it will slip."
This isn't a new phenomenon. Recently, Arkansas has recorded an increase in earthquakes, and even had the largest tremor recorded in the state in 30 years. Most of the earthquakes - 90 percent of - seen in the state since 2009 have occurred within six kilometers of underground salt water disposal sites associated with fracking operations. Earlier this year, those disposal sites where shut down because of the earthquake fears.
Similar concerns have arisen in West Virginia and Texas in recent years. Even last week's 5.8 earthquake that was centered in Virginia and shook much of the East Coast fueled speculation that fracking activities might be to blame. However, according to a report in The San Francisco Chronicle, the Virginia Department of Mines, Minerals and Energy says no fracking activities are underway near the quakes epicenter.