How the pursuit of oil and gas — by fracking — causes earthquakes
The whole point of fracking is to cause tiny earthquakes that fracture rock and release oil or natural gas. But the process of injecting high-pressure fluids into the earth’s surface can sometimes cause quakes that are big enough for us to feel
In mid-February, B.C.’s northeast was shaken by a series of earthquakes that both the province’s energy regulator and Natural Resources Canada say were linked to hydraulic fracturing, or fracking, for natural gas.
To release oil or gas from rock formations deep underground, companies blast a mix of water, chemicals and sand into the earth, a process that can sometimes trigger earthquakes.
Honn Kao is a seismologist, or earthquake scientist, who leads a Natural Resources Canada research project on “induced seismicity,” which refers to earthquakes caused by human activities. He says the whole point of hydraulic fracturing is to cause very, very small earthquakes, known as microseismicity, to fracture rock and release gas. “That is totally normal, because that’s the purpose of it.”
“It is not a particular surprise to see induced earthquakes that happened in the area where you have a lot of hydraulic fracturing operations or wastewater disposal injections,” Kao says in an interview. The two, he says, “usually go hand in hand.”
Six earthquakes with a magnitude of 3.0 or higher struck northeast B.C. from Feb. 8 to Feb. 13 local time. Source: Natural Resources Canada earthquake database. Map: Shawn Parkinson / The Narwhal
Naturally occurring earthquakes happen when underground rock suddenly breaks and there is motion along a fault. The sudden release of energy causes seismic waves that shake the ground.
When fracking fluids are injected into the earth’s subsurface at high pressure, they sometimes cause faults to slip earlier than they would naturally, inducing an earthquake, Kao explains. “So quite often [when] you have an increased level of hydraulic fracturing operation in the region, then the level of seismicity becomes larger, higher as well.”
But that doesn’t necessarily mean bigger earthquakes will occur. The vast majority, Kao says, are “small events that can be located or detected by seismometres, but not necessarily felt by local residents.”
The issue, Kao says, is when earthquakes are large enough to be felt in nearby communities. “That means the energy released by the earthquake is way bigger than the energy that we input through fluids.” The implication, he says, is that it must have triggered a fault where energy is already building up for an earthquake … “and you just simply make it happen earlier.”
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And that has long concerned local residents, from ranchers to people worried about their well-being and drinking water. Some northeast B.C. residents affected by fracking can no longer get earthquake insurance.
How do experts determine if an earthquake was caused by fracking?
Determining if an earthquake is induced by fracking requires investigation and research that includes examining the rock properties where the earthquake occurred and the injection history for nearby fracking operations, Kao explains. An earthquake is generally deemed to be induced if it occurs near an active fracking injection operation, he says.
Injection operations take place at relatively shallow depths, while many natural earthquakes occur at deeper depths. “Generally speaking, most of the induced earthquakes occur at or slightly above the injection depths.” But sometimes they are deeper, so seismologists have to examine different factors to infer whether a quake is caused by industrial activity.
Induced earthquakes usually occur in clusters, like the February earthquakes in B.C.’s northeast, Kao adds. “Once the hydraulic fracturing operations finish, they die down very quickly.”
The BC Energy Regulator requires any fracking operations that trigger an earthquake with a magnitude of 4.0 or greater to immediately suspend operations. In an emailed response to questions, the regulator said the operations may continue with written permission “once the well permit holder has submitted operational changes satisfactory to the BC Energy Regulator to reduce or eliminate the initiation of additional induced seismic events.”
Do fracking earthquakes cause damage?
Kao says B.C. hasn’t experienced induced earthquakes large enough to cause significant damage to buildings or infrastructure.Most earthquakes causing damage to buildings and infrastructure have a magnitude of 5.5 on the Richter scale or higher, Kao explains.
A cattle ranch in northeast B.C. reported the birth of twice as many calves as expected in the two days after a series of fracking-induced earthquakes in mid-February.
That doesn’t mean smaller earthquakes can’t have impacts. A B.C. family says a 4.3 earthquake on Feb. 11 precipitated a rush of calf births on its ranch, including premature twins, and the loss of most of their main water supply. While the quake may not have caused damage to buildings and infrastructure, Kao says “it certainly is a warning sign.”
He says it’s important to make sure a robust regulatory framework is in place that will prevent fracking-induced earthquakes from becoming large enough to cause significant damage in the community. “I think that is really the ultimate balance we want to achieve between public [safety and concerns] and the economic benefit of the industrial activity.”
The regulatory framework appeared to be working in the case of the February earthquakes he says, because they died down once the fracking operations responsible ceased.
Can fracking companies prevent earthquakes from happening?
Fracking companies can take steps to prevent earthquakes by controlling the number of injection wells or the volume of injected fluids. If an earthquake occurs, Kao says the operator can immediately change the injection pattern by reducing the injection rate, “or even completely shut down their injection operation.”
Kao and other researchers are studying the spate of February earthquakes in northeast B.C.
“We want to figure out why it happened, what we have missed, what kind of sign can we actually see beforehand? And hopefully we’ll build that into the regulatory framework, so that we can prevent these kinds of things … in the future.”
Another year of keeping a close watch
Here at The Narwhal, we don’t use profit, awards or pageviews to measure success. The thing that matters most is real-world impact — evidence that our reporting influenced citizens to hold power to account and pushed policymakers to do better.
And in 2024, our stories were raised in legislatures across the country and cited by citizens in their petitions and letters to politicians.
In Alberta, our reporting revealed Premier Danielle Smith made false statements about the controversial renewables pause. In Manitoba, we proved that officials failed to formally inspect a leaky pipeline for years. And our investigations on a leaked recording of TC Energy executives were called “the most important Canadian political story of the year.”
Here at The Narwhal, we don’t use profit, awards or pageviews to measure success. The thing that matters most is real-world impact — evidence that our reporting influenced citizens to hold power to account and pushed policymakers to do better.
And in 2024, our stories were raised in legislatures across the country and cited by citizens in their petitions and letters to politicians.
In Alberta, our reporting revealed Premier Danielle Smith made false statements about the controversial renewables pause. In Manitoba, we proved that officials failed to formally inspect a leaky pipeline for years. And our investigations on a leaked recording of TC Energy executives were called “the most important Canadian political story of the year.”
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