Although fracking itself can cause earthquakes, they are smaller and less frequently felt than earthquakes produced from underground injection control wells. A study in Seismological Research Letters found that fracking was the likely culprit of hundreds of small tremors in Ohio during 2013; another Ohio-based study that came out in 2015 pinpointed fracking as the cause of a 3.0 magnitude earthquake near
In 2011, fracking was associated with a 3.8 magnitude earthquake in British Columbia, Canada; that same year, in Blackpool, England, two earthquakes were directly linked to fracking operations. Fracking has also been linked to an earthquake that was felt in Garvin County, Oklahoma in 2011.
More typically when talking about fracking-related earthquakes, the conversation is referring to the seismic events triggered by injection wells, a common method of disposal for fracking waste. In the eastern and central United States, earthquake activity has increased about fivefold, from an annual average of 21 earthquakes above a 3.0 magnitude between 1967 and 2000, to more than 300 earthquakes over three years from 2010 to 2012.
According to scientists withthe U.S. Geological Survey (USGS), this increased seismic activity is associated with wastewater disposal wells in states such as Oklahoma, Colorado, Arkansas, Ohio and Texas. The threat of increased earthquake activity is also of concern for the seismically active state of California, where the Monterey Shale overlaps the San Andreas Fault.
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