Fracking Industry Has Changed Earthquake Patterns in Northeast BC
Impact on groundwater and migrating gases mostly unknown, critics say. A special report.
New research and presentations by both provincial and federal scientists show that the shale gas industry, which the B.C. government hopes will eventually supply proposed liquefied natural gas terminals with fracked gas, has caused more than a thousand earthquakes in northeast B.C. since 2006 and changed the region’s seismicity.
The earthquakes, ranging in magnitude from 1.0 to 4.3, include six events higher than 4.0 and more than 20 events that shook buildings and moved furniture in places like Fort St. John. Several events caused casing damage to horizontal wells. Moreover, industry-caused tremors remain an ongoing geological revolution for the region.
Earthquakes with a magnitude of about 2.0 or less are called microquakes and can’t be felt at the surface. Events above 3.0 can be felt on the ground, and tremors just larger than 4.0 can cause minor damage. A great earthquake, capable of extensive damage, typically measures a magnitude of 8.0.
Scientists originally thought that hydraulic fracturing wouldn’t trigger anything more than microquakes. But now that the technology has set off magnitude 4.4 quakes in Alberta, scientists are grappling to determine what kind of hazard industrial tremors might pose to pipelines, dams and other infrastructure.
At Upper Halfway, a community northeast of Fort St. John, residents have described the tremors as a series of crashes and bangs comparable to someone driving “a truck into the side of the house.”
The shale gas industry involves the injection of highly pressurized fluids into wells to crack open difficult oil and gas deposits. The injections create a network of cracks that can also connect to fault zones. The reactivation of these faults can then trigger an earthquake, scientists say.
Due to limited monitoring, industry and government lack a full understanding of how the wave of quakes is changing the flow of groundwater in the region or the migration of gases such as methane, radon and carbon dioxide into the atmosphere throughout northeast B.C.
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