Fracking caused small earthquakes in western Pennsylvania, PA-DEP confirms
From an Article by Dennis Owens, ABC News (WHTM – Harrisburg), February 17, 2017
The Pennsylvania Department of Environmental Protection made a big announcement Friday via an online webinar. “The Lawrence County event is properly classified as an induced tectonic seismic event,” droned an unseen scientist.
It was a webinar that only a geologist could love. Lots of science talk, geology terms and slides. There were no faces to be found. But we found the guy behind the Power Point and drilled down for a translation, in English.
“We found a connection between oil and gas activities and these detected seismic events, essentially earthquakes,” explained Seth Pelepko, a geologist who’s also in the DEP’s Oil and Gas program as the Chief of Well Plugging.
The report found that last April in Lawrence County near the Ohio border, five small earthquakes were caused by hydraulic fracturing or fracking in the Utica shale which is deeper than the more frequently mentioned Marcellus shale.
The DEP found that those earthquakes were the equivalent of a lightning strike, that they were caused by a very specific type of drilling in a very specific spot of instability. “There’s multiple contributing factors and they almost have to arrive in a certain combination to trigger an event,” Pelepko said.
The earthquakes are the first in Pennsylvania linked to drilling. The industry points out that there are more than 7,000 well statewide that have been drilled without incident. In a statement, it called the quakes, “isolated and exceptionally rare.”
But environmental group, Sierra Club PA, sees it differently.
“It’s the kind of activity that should not be allowed to move forward at this point because we know that it’s not safe,” Joanne Kilgour, Director of Sierra Club PA chapter, said.
The club typically opposes fracking because it believes fracking endangers drinking water, and now causes earthquakes. “It’s one more evidence that fracking poses threats to our communities,” Kilgour said. “We need to think very seriously about the kind of energy future that we want here in Pennsylvania.”
But fracking and natural gas drilling has been a fiscal geyser, so it’s not going anywhere anytime soon. Nor should it, says the DEP, which has increased its earthquake detection and is insisting keeping a close eye on drillers.
“I think the average person shouldn’t be concerned about this,” Pelepko said.
The five earthquakes were small, around 2.0 on the Richter scale, too small to be felt by people standing on the surface and only registering on seismometers.
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Fracking Earthquakes Confirmed in Penna.
Fracking Earthquakes in Pennsylvania
From an Article by David Pacchioli, Penn State University News, January 25, 2017
Last summer, with funding from the state Department of Conservation and Natural Resources, a Penn State team led by geophysicist Andrew Nyblade completed a major expansion of the Pennsylvania Seismic Monitoring Network, creating a system of 30 seismic stations spread across the Commonwealth. Located at Penn State campuses and state parks, the stations contain state-of-the-art ground motion sensors and GPS clocks. The added coverage provides for much more uniform seismic monitoring than was possible before.
Photo: Seismograph traces due to blasting activity look very different from those due to earthquakes (shown above).
Why do we need an expanded seismic monitoring network in Pennsylvania?
There are three reasons. One is that there are areas of natural seismicity in Pennsylvania—one in the Lancaster-Reading area, where there have been magnitude 4 earthquakes, and the other just south of Lake Erie on the Pennsylvania-Ohio border. The largest earthquake yet recorded in Pennsylvania was the Pymatuning earthquake of 1998, just south of Erie. That was a 5.2 magnitude event. When you get to magnitude 4 and 5 events, they can be felt, and they have potential to cause damage to structures, so we need to better understand those zones of seismicity.
Then there are the reasons related to oil and gas activities—induced seismicity, possibly by fracking and more probably by wastewater disposal.
How much seismic monitoring has been done here before, and what did it find?
In 2013-14 we were able to take advantage of a temporary array of seismic stations, part of the NSF EarthScope project, to get a good baseline read on seismicity within the state. What we found was that over 99 percent of the seismic activity in the state actually comes from blasting. There is blasting in coal mines and quarries going on all the time, and some of those blasts are equivalent to magnitude 2, 2.5 earthquakes. So there’s all this background seismic activity, and we need to be able to detect and locate those events so that we can discriminate between them and anything else that might be happening.
Are fracking-related earthquakes a real possibility in Pennsylvania?
We don’t yet know for sure, but Pennsylvania may have had its first fracking-induced seismicity already. In late April [2016], we had a series of seismic events in Lawrence County, near the Ohio border, that have been correlated with a well that was being fracked there.
The bigger concern, though, is with seismicity that’s induced from wastewater disposal. The flowback waters from fracked wells, and also the wastewater that comes from conventional oil and gas wells, has to be disposed of, and a common practice is to pump it back into the ground. There’s been a huge ramp-up of seismicity in places in Oklahoma, Kansas, Texas, and some places in Canada, and most of that is related to wastewater disposal, not to fracking itself.
Would it be possible that any induced activity would be on a par with natural earthquakes that have been recorded in the state?
Yes. In Oklahoma there have been events induced by wastewater injection that were 5.7, 5.8 magnitude. Magnitude 4s have been recorded in Arkansas and Texas related to wastewater injection. The largest fracking-related events reported so far are magnitude 4s, and those have been in Canada. So there is potential for magnitude 4s and 5s—potentially damaging earthquakes—that could be induced by either fracking or wastewater disposal.
Is there something we can do to mitigate the concern?
Absolutely. As we monitor seismicity across the state, we can detect small events when they happen and determine if they are related to fracking or to wastewater disposal, and if so notify the Department of Environmental Protection, who can then ask the well operator to shut down or take other steps. That’s one of the main purposes of the network, to be able to detect events before they get too large, so that the state authorities can take remedial action.
>>> Andrew Nyblade, professor of geosciences, studies seismology and tectonics in Africa, Antarctica, and North America. He is co-director of the Marcellus Center for Outreach and Research.
>>> This interview first appeared in the Fall 2016 issue of Research/Penn State magazine.
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