USGS Links Fracking to Earthquakes

A hydraulic fracturing drilling rig. Image by Cliff Weathers. Some rights reserved.

The American Midwest has seen something of an earthquake boom in recent years, and speculation that the earthquakes are related to shale gas drilling has run rampant. In 2001, the frequency of earthquakes from Montana to Alabama began to rise, the number of quakes of magnitude 3.0 or greater reaching 87 in 2009. The 134 quakes of that magnitude recorded in 2011 represent a sixfold increase over 20th century levels.

As shale gas production has grown at a rate of 50 percent per year over the past 5 years, official concern has been growing. Back in November, we wrote about a report from the Secretary of Energy laying out recommendations to improve the safety and reduce the environmental impact of shale gas development, including a section on eliminating the use of diesel in fluids used for hydraulic fracturing.

Hydraulic fracturing, commonly called “fracking,” is a method of extracting gas and petroleum from source rocks. The injection of fracturing fluid into a drilled wellbore creates an extended crack in underground rocks typically under high pressure, allowing petroleum or gas to flow from the porous rocks where it is trapped to a natural reservoir from which it can be extracted.

The U.S. Geological Survey (USGS) recently released the abstract of its report finding a link between fracking and the sharp jump in earthquakes, the latest in a wave of research on the process. It follows a USGS report from last August that noting a series of 50 small earthquakes that came shortly after fracking operations began in Oklahoma. In November, a British shale gas developer admitted that they likely caused small earthquakes in the vicinity of their operations, and in March, Ohio regulators found that some fracking processes probably induced twelve earthquakes in northeastern Ohio.

The USGS thinks most of the earthquakes are caused not by the fracking itself, but from the disposal of the millions of gallons of wastewater produced by each well – often by injecting it back into the earth, as regulators found in Ohio. The bottom line is that the dramatic increase in earthquakes has never been seen outside of volcanic activity or in the absence of a main earthquake, neither of which exist in this region.

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