Earthquakes in the nation's capitol are as rare as hen's teeth. The epicenter of Tuesday's quake was in Mineral, Virginia, which is located on three very quiet fault lines. The occurrence of yet another freak earthquake in an unusual location is leading many anti-fracking activists (including me -- they have just started fracking in Stratford, which is 40 minutes from New Plymouth) to wonder whether "fracking" in nearby West Virginia may be responsible.
Fracking, or hydraulic fracturing, is the process of initiating and subsequently propagating a fracture in a rock layer, employing the pressure of a fluid as the source of energy. The fracturing is done from a wellbore drilled into reservoir rock formations, in order to increase the extraction rates and ultimate recovery of oil and natural gas and coal seam gas.
How Fracking Causes Earthquakes
According to geologists, it isn't the fracking itself that is linked to earthquakes, but the re-injection of waste salt water (as much as 3 million gallons per well) deep into rock beds.
Braxton County West Virginia (160 miles from Mineral) has experienced a rash of freak earthquakes (eight in 2010) since fracking operations started there several years ago. According to geologists fracking also caused an outbreak of thousands of minor earthquakes in Arkansas (as many as two dozen in a single day). It's also linked to freak earthquakes in Texas, western New York, Oklahoma and Blackpool, England (which had never recorded an earthquake before).
Industry scientists deny the link to earthquakes, arguing that energy companies have been fracking for nearly sixty years. However it's only a dozen years ago that "slick-water fracks" were introduced. This form of fracking uses huge amounts of water mixed with sand and dozens of toxic chemicals like benzene, all of which is injected under extreme pressure to shatter the underground rock reservoir and release gas trapped in the rock pores. Not only does the practice utilize millions of gallons of freshwater per frack (taken from lakes, rivers, or municipal water supplies), the toxic chemicals mixed in the water to make it "slick" endanger groundwater aquifers and threaten to pollute nearby water-wells.
Horizontal drilling and multi-stage fracking (which extend fractures across several kilometres) were introduced in 2004.
The Research Evidence
I think it's really hard to deny there's a connection when the frequency of Arkansas earthquakes dropped by two-thirds when the Arkansas Oil and Gas Commission banned fracking (see http://www.huffingtonpost.com/2011/04/21/fracking-shutdown-earthquakes-arkansas_n_851930.html). Note that they didn't stop entirely, which suggests that fault disruption may persist even after fracking stops.
Braxton County West Virginia also experienced a marked reduction in their quakes after the West Virginia Oil and Gas Commission forced fracking companies to cut back on the pressure and rate of salt water injection into the bedrock (see http://www.hurherald.com/cgi-bin/db_scripts/articles?Action=user_view&db=hurheral_articles&id=43334).
According to a joint study by Southern Methodist University and University of Texas-Austin, earthquakes started in the Dallas/Fort Worth region after a fracking disposal well there began operating in 2008 and stopped when it was closed in 2009 (see http://www.watershedsentinel.ca/content/does-gas-fracking-cause-earthquakes).
Blackpool, England banned fracking immediately, without waiting to see if more earthquakes would occur.
The Need for Federal Action
Despite strong anti-fracking movements in New York, Pennsylvania and West Virginia -- based on dozens of cases of contaminated well water, poisoned livestock, destruction of wildlife, and tap water that catches fire and explodes -- fracking has proved extremely difficult to regulate on a state and local level. New York governor Andrew Cuomo seems intent to allow the New York fracking to lapse. And a West Virginia judge has recently overturned Morgantown's ban on fracking, on the basis that it violated the constitutional rights of Northeast Natural energy company.