Researchers study aftershocks of Fox Creek earthquake possibly linked to fracking
EDMONTON - Researchers recorded as many as 100 aftershocks after a 4.4-magnitude earthquake near Fox Creek, including one that measured 2.3 on the Richter scale.
Preliminary analysis of the data indicates the Jan. 22 earthquake was caused by hydraulic fracturing, University of Calgary geophysicist David Eaton said Monday.
“If the earthquake took place very deep in the Earth’s crust, it’s less likely that it was induced by hydraulic fracturing and more likely that it’s natural,” Eaton said.
“Our results are consistent with it being induced by hydraulic fracturing — in other words, quite a shallow earthquake (within the first three kilometres of the surface.)”
The earthquake was recorded at 11:49 p.m. about 33 kilometres west of Fox Creek in an area that has seen episodes of increased seismic activity since late 2013.
The Alberta Energy Regulator is investigating and a spokesman has said preliminary information indicates it may be related to hydraulic fracturing operations.
On Jan. 23, Eaton and two other U of C researchers loaded four seismograph stations into a rented truck and drove toward the quake’s epicentre. They were recording aftershocks by the morning of Jan. 24.
Eaton said he is “very confident” the equipment recorded four significant aftershocks. The total number may be as high as 100, he said.
Measuring aftershocks can help pinpoint an earthquake’s exact location and its depth below the Earth’s surface. Magnitude and timing of aftershocks can provide information about the earthquake’s dynamics.
Eaton said a 3.8-magnitude earthquake on Jan 14, 38 km west of Fox Creek, may also be related to fracking. “Being in the same area and not too far apart in time, one might conclude that there is likely to be something very similar between the two events,” he said. “And they are both in an area of high industry activity.”
Gail Atkinson, the NSERC/TransAlta/Nanometrics Industrial Research Chair in Hazards from Induced Seismicity at Western University, said she is “99.99 per cent” certain the Jan. 22 earthquake resulted from hydraulic fracturing.
“That area did not have a lot of seismicity until they started hydraulic fracturing operations in 2013,” Atkinson said. “We have seen — in that area in the last year — hundreds of earthquakes, and we never saw any before.”
Fracking operations should be evaluated more carefully so that risks can be mitigated, she said. “We need to keep working on ways to make the technology better so that we don’t get any nasty surprises.”
The Jan. 22 earthquake was felt by Fox Creek resident Lee-Anna Jack, who was in her bedroom watching TV with her husband when the door slammed open and the bed moved.
“It felt like when you’re on a roller-coaster and how your stomach does flip flops,” Jack said.
Jack, a 30-year resident of Fox Creek, had never experienced anything like it before. She posted to Facebook and learned the neighbour directly across the street had felt something similar.
Jack suspects the quake could be linked to fracking. In the long term, that may mean that work in the community will have to change, she said.
Town councillor Jim Hailes said the community needs more information about what happened.
“I’d assume that if the regulator discovers there’s a problem, they will move to do something about it.”
With files from Alexandra Zabjek