A new study on the practice of hydraulic fracturing has found a direct connection to some 400 micro-earthquakes in an Ohio town. This is the second report on the Utica Shale this year. The town is one of very few where the quakes took place on a fault.
The new study, published Tuesday in the journal Seismological Research Letters, focuses on the eastern town of Canton, Harrison County, and three particular wells. It has found that the three wells operated in September-October 2013 in the Utica Shale caused 10 quakes of magnitude 1.7-2.2, among others.
But the case of Harrison County is one of a very few where, according to seismologist and lead author Paul Friberg, the quakes happened on a fault line.
Other locations where this happened included the United Kingdom, British Columbia in Canada and Poland Township, Ohio, according to LiveScience.
An earlier March study led to scientists with Ohio’s Department of Natural Resources to shut down seven other wells in the Poland Township after fracking there led to two small quakes.
The current spate of Harrison County quakes struck less than 1.4km (1 mile) below ground, with tremors starting to be felt 26 hours after fracking started on September 29, 2013. This was followed by a total of 190 earthquakes in the 39 hours just two days later. When the pressure stopped, so did the quakes, according to the study.
Ohio Department of Natural Resources spokeswoman Bethany McCorkle told the AP that over the past year new seismic monitoring equipment has been installed in eastern Ohio in order to monitor for stronger quakes.
There is also an opinion that some underground dangers cannot be spotted until hydraulic fracturing is carried out there. In this sense, the findings can be used to prevent further, worse quakes.
It has been known for a while that hydraulic fracturing — which implies pumping huge quantities of water, chemicals and sand into rock to shatter it and extract oil and gas — leads to earthquakes. But it was previously thought that the effect is negligible. Now a growing body of evidence seems to suggest otherwise.
Rowena Lohman, an assistant professor of geophysics at Cornell University, who was not involved in the study, told AP that the oil and gas community have “known for a really long time, going back to the ’70s, that when you do any subsurface manipulation you cause small earthquakes,” but also that “the big question is: are we doing something now that increases the probability that it will induce larger quakes?”
It was found in another, unrelated study that just four wastewater wells in Oklahoma — where water is stored after fracking completes — are to blame for a massive number of earthquakes this year all taking place within a 30km radius.
As with Ohio, incidences of earthquakes increasing as a result of fracking have been witnessed largely in Oklahoma. Similar problems are affecting Colorado, where a well was shut down after a small earthquake caused by an injection well in Weld County.
Idaho and Texas are among other states which have directly suffered from the practice.
In July this year, the USGS also released a report that predicted the number of states with earthquakes to double over the next 50 years. This prediction concerns events that actually cause damage.