Fracking behind Alberta quakes, study suggests

New research suggests that hydraulic fracking of oiland gas wells is behind earthquakes caused by humans in WesternCanada.

A study, publishedTuesdayby a group of top Canadianresearchers, says problems in Alberta and British Columbia aren'tbeing caused by injecting waste water underground. It's a major stepin understanding seismic events that have already led to changedregulations in Alberta and caused public concern in both provinces.

• Earthquakes in Alberta to become more frequent and stronger, expert says
• Fox Creek fracking operation closed indefinitely after earthquake
• 4.4-magnitude earthquake recorded near Fox Creek
• Fracking and earthquakes: Exploring the connection

"It's critical that we get to a complete scientificunderstanding of the issue," said David Eaton, a University ofCalgary geophysicist and a co-author of the study.

Fracking involves pumping high-pressure fluids underground tocreate tiny cracks in rock to release natural gas or oil.

Scientistshad previously concluded that oilpatch activity can causeearthquakes by making it easier for faults in underground rock toslip, but they didn't know whether the Canadian quakes were causedby fracking or by the disposal of waste water by injecting it backunderground.

Public interest has been high, especially after a tremblor inJanuary shook pictures on the walls of homes in Fox Creek, Alta., acommunity in the centre of the Duvernay oil and gas field. Measuringbetween 4.2 and 4.8 on the Richter scale, the quake was the largestof hundreds of similar shakers around the community since 2013.

Eaton and his colleagues began with a database of more than12,000 fracked and disposal wells drilled between 1985 and 2015.They cross-referenced that with another database of seismic eventsover that time.

A complex statistical analysis pinned the blame convincingly onfracking and not disposal, Eaton said.

"There are more earthquakes in Western Canada that are morerelated to hydraulic fracturing than waste-water injection by afactor of about two."

Eaton said the situation is reversed in the United States, wherewaste-water disposal is considered to be behind most human-causedseismic activity.

That doesn't mean that a lot of wells cause earthquakes. Eatoncalculates that about 0.3 per cent of fracked wells create problems.

But there are enough wells drilled for even that tiny fraction tobe a concern.

"Even at 0.3 per cent, because of the very large number ofhydraulically fractured wells, it still represents an issue that isof high priority to address scientifically," said Eaton.

Alberta's energy regulator has already changed regulations forthe industry as a result of the Fox Creek earthquakes. Eaton saidregulators in British Columbia are also considering changes.

"The regulators have been quite responsive."

Eaton suggested his findings raise questions about how well thegeology of heavily fracked oilfields in Alberta and British Columbiais understood,

"The occurrences in Canada have come as a surprise -- in somecases to industry -- because there was a belief that all thepotential faults had been identified," he said. "One of the thingswe're actively researching is to find new and better ways toidentify these features.

"We're looking for the signature of critically stressed faultsin new and different ways."

Scientists are aware of the pressure they face getting the issueright, Eaton said.

"There's a mixture of science and the whole social-politicalaspect of this."