Scientist still gathering data to determine cause of Fox Creek earthquake
If you believe Andrew Nikiforuk of The Tyee, Alberta broke a world record on Jan. 22 for the strongest earthquake induced by hydraulic fracturing operations. But the Alberta Geological Survey says scientists haven’t collected the data yet to concluding fracturing was even the cause of the 4.4 Fox Creek earthquake.
Natural Resources Canada recorded the quake just before midnight 30 kilometres west of Fox Creek (268 kilometres WNW of Edmonton). According to the Alberta Energy Regulator, in December 2013 there were 18 seismic events between magnitudes 2.7 and 3.7 recorded in the region and in mid-January 2014 five events were recorded between magnitudes of 2.4 and 3.8. Earthquake swarms are one of the signs of fracturing-induced seismic activity.
One person reported to the federal department that they felt weak shaking, but no damage to buildings. Local accounts suggest the quake was felt.
“It was like a big gust of wind hit the house. The back door opened and I felt the couch move. We were all up at the time. We had no idea what had just happened until I got up and saw it on Facebook,” Kelli McPhee told the Fox Creek Times Online.
Hydraulic fracturing – pumping fluid downhole at high pressures to fracture geological formations and free up oil and gas – does cause small earthquakes, though they are rarely felt at surface.
In 2012, the BC Oil and Gas Commission released a report on 272 minor seismic events (2 to 3.8 magnitude) that scientists concluded were induced by fracturing. Only one was felt at surface, faintly by a brush crew.
Sometimes, my media colleagues mistakenly attribute earthquakes to fracturing when the cause is something else, such as the 13 small quakes that CBC reported last November were the fault of fracturing when the real culprit was a waste-water disposal well.
The Fox Creek quake may have been induced by fracturing, but Dr. Todd Shipman, manager, landscapes and geological hazards, of the Alberta Geological Survey says his team has not yet gathered the data from the service company crews so they can correlate seismic data with pumping information.
“There’s information we don’t have from operators. We’re trying to collect that information,” Dr. Shipman said in an interview with Beacon News. “We don’t have pump rates or activity.”
Shipman says earthquakes can occur at various times within the fracturing cycle, such as when the crew is pumping, after it stops, or when they withdraw fluid. Once scientists get the data from the service company, they can crunch the numbers and look for correlations between quake activity and fracturing activity.
Shipman cautions that scientists can never state with certainty that fracturing induces earthquakes.
“We look for correlation, we look for likelihood, but you’re never going to have a definitive answer,” he said.
The strength of the 4.4 quake is so unusual it raises the question if the tremor was caused naturally, says Dr. Shipman.
It also begs the question if seismologists should be worried about magnitude or effect on surface.Dr. Shipman explains that in some regions, like Oklahoma, earthquakes of 2.0 or less have been felt on surface. And regulators become concerned when people feel quakes or have their property damaged.
“Whether it’s natural or induced, this is something we have to address,” he said. “We’re [Alberta Geological Survey] in the process of coming out with a response to this.”
In the meantime, claims of fracturing-induced earthquakes should be based on analysis by seismologists who have completed their analysis and speak confidently about correlation and causation.
Otherwise, such claims are propaganda, not news.
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