Fracking has once again been shown to cause earthquakes, according to a study released by the Seismological Society of America on January 5.
A rare “felt” earthquake in Ohio in March 2014 was definitely caused by practices associated with hydraulic fracturing, the gas-and-oil extraction method that entails injecting highly pressurized water infused with chemicals to loosen the oil and gas trapped between shale layers, said researchers at Miami University in Ohio.
Before fracking began in the state, earthquakes were unheard-of, the researchers noted in a statement. Normally, the earthquakes generated by fracking are “micro,” the study authors said, not felt by humans. But a 3.0-magnitude quake in March 2014 that caused the closure of a well is was definitely triggered by the controversial practice, said the research published in the online Bulletin of the Seismological Society of America (BSSA).
“These earthquakes near Poland Township occurred in the Precambrian basement, a very old layer of rock where there are likely to be many pre-existing faults,” said study co-author Robert Skoumal of Miami University, in the statement. “This activity did not create a new fault, rather it activated one that we didn’t know about prior to the seismic activity.”
It was just the most jarring in a series of five recorded earthquakes that ranged from 2.1 to 3.0, the researchers said, all of which occurred within half a mile of a group of oil and gas wells operated by Hilcorp Energy as it conducted fracking operations. The public did not report feeling anything but the 3.0 quake, the scientists said.
“It remains rare for hydraulic fracturing to cause larger earthquakes that are felt by humans,” the researchers’ statement said. “However, due to seismic monitoring advances and the increasing popularity of hydraulic fracturing to recover hydrocarbons, the number of earthquakes—felt and unfelt—associated with hydraulic fracturing has increased in the past decade.”
Fracking has been implicated in other earthquakes as well, including a string of them in and around Dallas in 2012.
In addition, last May the U.S. Geological Survey (USGS) warned Oklahoma officials to be prepared for more numerous and stronger earthquakes than in the past, noting that from 1975 to 2008, central Oklahoma had experienced one to three 3.0-magnitude earthquakes a year, as opposed to an average of 40 annually between 2009 and 2013. Further, the quakes did “not seem to be due to typical, random fluctuations in natural seismicity rates,” the USGS said. “The analysis suggests that a likely contributing factor to the increase in earthquakes is triggering by wastewater injected into deep geologic formations.”
This is what is done with the water left over from fracking. In 2011 Oklahoma experienced its largest earthquake ever, measuring 5.6, which damaged homes and prominent buildings.
Last year, the Oklahoma Geological Survey received nearly $2 million to research potential links between fracking and earthquakes.