An earthquake has struck northern Alberta where past tremors have been blamed on hydraulic fracturing from the oil and gas industry.
Fox Creek, an oil and gas town of 2,000 people, is more than 200 kilometres northwest of Edmonton.
Hydraulic fracturing, commonly known as fracking, was found to be the likely cause of a January 4.4-magnitude earthquake in the same area. The tremor caused some minor damage, reported CBC News.
Fracking is a drilling process where a high-pressure mix of water and chemicals is injected into the earth to break through rock and release the gas inside.
It's a controversial process because of the massive amounts of water that must be transported to each site. Critics also worry about the chemicals involved, as well as the potential to cause tremors.
After the January earthquake near Fox Creek, the Alberta Energy Regulator set up new rules to monitor seismic events.
Since then, a company fracking in the Fox Creek area reported two earthquakes with magnitudes of 2.2 and 2.1 on May 28, according to The Tyee. A third measuring 2.4 was also detected on April 16 in the same region.
Gail Atkinson, who researches induced seismic hazards at Western University in Ontario, found that a "swarm" of 25 earthquakes with magnitudes of 2.5 to 3.5 between 2013 and 2014 in the Crooked Lake region near Fox Creek corresponded "closely to hydraulic fracture treatments of oil and gas production wells in the immediate vicinity."
Fracking is an increasing concern in the U.S. In Oklahoma for example, earthquakes are occurring at a rate that's 600 times the historical average. In 2014, the U.S. state experienced 585 earthquakes of 3.0-magnitude or higher, compared to an average of 1.6 quakes annually between 1978 and 2008.
They are "very likely triggered" by wastewater injection that's part of the fracking process, said a report released by the state this spring.
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A blog post by the Natural Resource Defense Council explains that "Opponents of such regulation [of fracking] claim that hydraulic fracturing has never caused any drinking water contamination. They say this because incidents of drinking water contamination where hydraulic fracutring is considered as a suspected cause have not been sufficiently investigated." It then goes on to list more than two dozen instances of water pollution to which hydraulic fracking is believed to have contributed. A new waterless method of fracking has been proposed, but environmentalists are skeptical.
Methane is a greenhouse gas and major component of shale's carbon footprint. Cornell Professor Robert Howarth said about a study he conducted, "Compared to coal, the footprint of shale gas is at least 20 percent greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years."
Researchers at MIT found that replacing coal power plants with natural gas plants could work as part of a plan to reduce greenhouse emissions by more than 50 percent.
Several earthquakes both in the U.S. and abroad have been linked to the hydraulic fracturing process. One British company, Cuadrilla Resources, admitted in a report that its hydraulic fracturing process well "did trigger a number of minor seismic events."
The industry currently employs more than 1.2 million people in the U.S., and the Department of Energy estimates that natural gas resources have increased nearly 65 percent due to fracking, according to a TreeHugger graphic. Additionally, the gas industry accounts for about $385 billion in direct economic activity in the country, a Nature piece reports.
Fracking is exempt from the Safe Drinking Water Act of 2005, thus allowing companies to conceal the chemicals used in the process.
Former chief of staff to President Clinton and former head of the Center for American Progress John Podesta says natural gas can serve "as a bridge fuel to a 21st century energy economy that relies on efficiency, renewable sources, and low-carbon fossil fuels."
The fracking process can require around five million gallons of water. In some cases less than a third of that water is recovered.