Martin Chapman, the head of Virginia Tech’s Seismological Observatory says the cause of last month’s earthquake in Mineral was a lot of stress centered in an area with several favorable faults.
"It turns out the earthquake was on a kind of a north, northeast trending reverse fault," says Chapman.
Chapman says seismologists have long predicted an earthquake would occur there; they just didn’t expect it to be as large as a 5.8. Since 2004, oil companies have been using the latest practice of hydraulic fracturing, injecting a high pressure water, sand, and chemical solution horizontally into the earth’s crust to split apart rock and release oil and gas deposits.
“In some cases you can trigger larger earthquakes on pre-existing faults that are already near the critical stress level," he says.
Chapman says as hydrofracking becomes more common, especially in the Appalachian region, there may be an increase in the number of earthquakes in Virginia and surrounding areas.