A report by the Ohio Department of Natural Resources (DNR) suggests a possible link between hydraulic fracturing, or “fracking,” and earthquake activity in the Youngstown area.
The use of natural gas for electric generation has been growing in recent years, due in part to rising environmental concerns over coal-fired power plants and the large domestic supply of unconventional shale gas produced through technologies like fracking. As a result fracking is coming under more scrutiny.
While studies like one recently done by the University of Texas show no direct link between the process and groundwater contamination, the ODNR report suggests the process might be a factor in certain earthquakes.
Since March 2011, the Youngstown area has experienced 12 low-magnitude seismic events along a previously unknown fault line. These events ranged from 2.1- to 4.0-magnitude and were recorded by the DNR’s Ohio Seismic Network (OhioSeis). The state entity works with the U.S. Geological Survey to monitor all seismic activity in Ohio.
While Ohio already meets or exceeds U.S. Environmental Protection Agency (EPA) standards for Class II deep injection wells, the state is moving to revamp its oversight of this process. The ODNR could attach special conditions to natural gas permits or seek potential changes to the Ohio code.
The 2011 earthquakes are distinct from previous seismic activity in the region because of their proximity to a Class II deep injection well, known as the Northstar 1 well. “In fact, all of the events were clustered less than a mile around the well,” the DNR said in the report.
The state agency found that many “coincidental circumstances appear to make a compelling argument for the recent Youngstown-area seismic events to have been induced.”
Evidence gathered by ODNR regulators and geologists suggests that fluid from a deeply drilled injection well intersected an unmapped fault in a near-failure state of stress, causing movement along the fault.
Further analysis and detailed modeling of all factors must be completed on the Northstar 1 well and the surrounding geology in order to get a better understanding of what happened, ODNR said.