Ohio earthquakes 'caused by fracking' suggests study

A series of earthquakes that were experienced in 2011 by Youngstown, Ohio, have been attributed to the water injection method of hydraulic fracturing (fracking) by scientists after two years of research. Previously the town had never experienced earthquakes, but for nine months in 2011 they became an increasing phenomenon that continued to increase in intensity.

According to a researcher from Columbia University, Won-Young Kim, the 167 earthquakes that occurred in the area in 2011 were due to the single fracking well that was in operation. Previously no earthquakes had been recorded in Youngstown until two weeks after the Northstar 1 injection well began operations at the end of 2010. The 9,200 foot well began having wastewater pumped into it, which was created by shale drilling operations.

An average of 12 earthquakes a month were recorded from the start of 2011 to February 2012. The largest of them was recorded after the final day of wastewater injection operations at the well. Some 495,622 barrels of wastewater at had been pumped into the well before the Ohio Department of Natural Resources shut it down due to the escalation of the earthquakes. Once the well had ceased to be used, the earthquakes petered off.

Mr Kim's research, which is published in 'The Journal of Geographical Research', reveals that the pressure levels within the well had a direct correlation to the intensity of the Youngstown earthquakes. The study also tracked the seismic activity of the area and compared the profile to the earthquakes epicentres. It was found that they occurred at the well site or at points along a connecting fault line.

It was found that the high pressure of the wastewater forced it to move along the fault line, leading to an increase in pressure on the rock formations along the line. This pressure increased the likelihood of earthquakes, which moved further away from the well as more water was pumped in and forced along the fault line.

However, the study did not find that fracking activities will always result in earthquakes. In the case of Youngstown, the earthquakes were caused by the fact that the well was unknowingly located over a fault line.