US geologists link small quakes to fracking

Geologists in Ohio have for the first time linked earthquakes to the intensely scrutinised drilling method called hydraulic fracturing, or fracking, leading the state to issue new permit conditions in certain areas that are among America's strictest.
A state investigation of five small tremors last month in the Youngstown area, in the Appalachian foothills, found the injection of sand and water that accompanies hydraulic fracturing, in the Utica Shale may have increased pressure on a small, unknown fault, said State Oil & Gas Chief Rick Simmers yesterday. He called the link "probable."
While earlier studies had linked earthquakes in the same region to deep-injection wells used for disposal of fracking wastewater, this marks the first time tremors in the region have been tied directly to fracking, Simmers said. The five seismic events in March couldn't be easily felt by people.

Fracking involves pumping huge volumes of water, sand and chemicals underground to split open rocks to allow oil and gas to flow. Improved technology has allowed energy companies to gain access to huge stores of natural gas but has raised widespread concerns that it might lead to groundwater contamination and, yes, earthquakes.
A US government-funded report released in 2012 found that two worldwide instances of shaking can be attributed to actual extraction of oil and gas, as opposed to wastewater disposal in the ground a magnitude-2.8 quake in Oklahoma and a magnitude-2.3 quake in England. Both were in 2011.
Later, the Canadian government tied quakes in British Columbia's Horn River Basin between 2009 and 2011 to fracking. Those led to stricter regulations, which news reports indicated had little effect on the pace or volume of drilling.

The oil and gas drilling boom targets widely different rock formations around the United States, so the Ohio findings may not have much relevance to other areas other than perhaps influencing public perception of fracking's safety. The types of quakes connected to the industry are generally small and not easily felt, but the idea of human activity causing the earth to shake often doesn't sit well.
The state says the company that set off the Ohio quakes was following rules and appeared to be using common practices. It just got unlucky, Simmers said.
Gerry Baker, associate executive director of the Interstate Oil and Gas Commission, said state regulators across the US will study the Ohio case for any implications for the drilling industry. A consortium of states has already begun discussions.