More industry-linked earthquakes have shaken up Alberta's oil and gas fields in recent weeks from Fox Creek to Peace River, say experts and regulators.
In Fox Creek, Alberta, where industry triggered a 4.4 magnitude earthquake, a company fracking in the Duvernay Formation has reported more tremors.
"On May 28, an operator in the Fox Creek area reported two seismic events, of a magnitude 2.2 and 2.1 respectively," confirmed Ryan Bartlett, a spokesperson for the Alberta Energy Regulator.
"The events were associated with hydraulic fracturing operations," said Bartlett, "and were reported to the [regulator] as required by Subsurface Order #2," a new set of regulations to monitor seismicity set up last February.
In addition, a shallow 3.5 magnitude earthquake occurred near Rocky Mountain House in central Alberta where a history of quick and high-volume gas extraction from the Strachan gas pool has triggered swarms of tremors since 1976.
Gail Atkinson, one of Canada's foremost experts on earthquake hazards, said the June 2 event near Rocky Mountain House "appears likely to have been triggered by hydraulic fracture operations nearby, though the details of those operations are not yet available."
The fracking of tight oil formations along the Rocky Mountains, says a recent industry case study, can divert fracking fluids into faults with the risk of "generating induced seismicity of large enough magnitude to be felt at the surface."
Just northeast of the town of Peace River, residents recently heard a loud boom as two earthquakes shook an area where industry extracts bitumen by injecting steam into the ground. The regulator's Alberta Geological Survey branch is investigating the events.
"We can't take things out of the earth and expect things not to move," said nearby resident and rancher Carmen Langer.
'Traffic light system' in place
Fluid injection of gases or liquids by the oil industry deep into the ground, including salt water disposal, steam injection, and hydraulic fracturing has been known to trigger earthquakes since the 1960s.
The industry has also caused earthquakes from California to the Netherlands by extracting oil and gas from a formation at such high rates that the formation begins to subside and fracture.
After The Tyee reported last January that fracking had caused a swarm of earthquakes as well as a 4.4 magnitude earthquake near Fox Creek, the Alberta Energy Regulator set up a seismic reporting "traffic light system."
The novel system forces companies to report seismic events greater than a magnitude of 2.0, and to shut down operations once a 4.0 magnitude quake is observed near their operations.
Atkinson, who is also the NSERC/TransAlta/Nanometrics Industrial Research Chair in Hazards from Induced Seismicity at Ontario's Western University, said that the traffic light system is "a good start, but like many approaches it is not perfect."
"Once a sequence [of earthquakes] is initiated, it may continue for some time, with larger events continuing to occur after a company has been ordered to stop," she said.
Furthermore, "the largest event in the sequence might happen first. Thus the approach is a sensible precaution, but not foolproof protection."
Experts at a 2014 Banff workshop on the subject questioned the effectiveness of traffic light systems because "there are few examples where such systems have been successfully used to modify an operation to mitigate seismicity."
Since the regulator set up its traffic light system, three reportable seismic events have occurred in the Fox Creek area: a 2.4 magnitude event on April 16, 2015, and 2.2 and 2.1 magnitude events on May 28, 2015.
'We need to understand why'
Earthquakes triggered by the technology of hydraulic fracturing and waste disposal wells in Ohio, Texas, British Columbia, Oklahoma, Arkansas, and Alberta have increased the need for more seismic monitoring throughout the oil patch.
One company, Spectraseis, advises companies that "Seismic events near oil and gas wells and water injection sites can lead to costly operational suspensions or shut downs, wellbore integrity losses, and serious public and regulatory concerns."
At a recent meeting in Fox Creek, Todd Shipman, manager of landscape and geological hazards for the Alberta Geological Survey, reportedly told concerned city councillors that hydraulic fracturing will cause small earthquakes, but that the large January tremor occurred after fracking operations stopped.
"Four point four magnitude earthquakes are not normally seen so we need to understand why," Shipman said. "The [regulator] is trying to develop a geological framework to see what is going on in the Fox Creek area."
The U.S. Geological Survey has called for better monitoring and response to the industry-triggered events.
"The general public is the most important stakeholder because they may be exposed to potential injury and damage," warned the USGS in a recent paper.