In the heartland of Oklahoma sits a pretty town dotted with American flags and a quaint main street of century-old brick buildings. But in Guthrie, the devastating impact of oil-industry-induced earthquakes is being felt hard.

Look closely and you see cracks in the historic buildings, where the old masonry is giving way to a shifting ground. Guthrie has seen a wave of earthquakes since hydraulic fracturing — or fracking — picked up in the area.

There's no denial from the Oklahoma government or seismologists from 20 countries who met in Reno, Nev., last week that practices related to fracking are behind the swarms of earthquakes that have increased in volume and intensity since 2011.

"There's definitely a relationship between deep well disposal and the earthquake activity," the state's oil and gas regulator, Tim Baker, said in an interview with CBC News, referring to the practice of injecting fracking waste water deep into the ground.

Hydraulic fracturing sites dot the landscape near Guthrie, Okla. The historic town has been shaken by hundreds of earthquakes that are damaging homes and heritage brick buildings on its main street. (Terry Reith/CBC)

At the Reno meeting, seismologists from Canada also warned that fracking in Alberta and British Columbia could bring similar consequences.

"In Western Canada, most of the seismicity we're experiencing is being actually directly related to hydraulic fracturing," says Gail Atkinson, a specialist in induced seismicity from Western University in London, Ont.

While there's been little noticeable damage in Canada so far, she warns it could happen.

"I think damage is a function of getting the wrong ground motions in the wrong place at the wrong time."

Atkinson helped chair a day-long session on the impacts of fracking and earthquakes at the annual meeting of the Seismological Society of America. She also presented her own Canadian research.

She says smaller earthquakes shouldn't be ignored because they can lead to larger, more destructive ones.

"For every 100 magnitude three earthquakes, you'll get 10 of magnitude four and one magnitude five," she says. "The higher the rate of seismicity, the greater likelihood you'll trigger at least one large event."

In Alberta's Fox Creek area, there were 367 tremors measured in 2015, according to Alberta's Energy Regulator. Most of them were under magnitude three, but a magnitude 4.4 hit in January 2015, and an even stronger magnitude 4.6 shook the area in January 2016.

After that, the regulator shut down a nearby fracking operation. It has now restarted.

Atkinson says it's wise for Canada to pay attention to what's happening in Oklahoma.

The Oklahoma experience

Oklahoma, like Alberta, is oil country. The landscape is dotted with huge pumpjacks and sites where waste water from fracking is injected deep into the ground.

The petroleum industry also fuels local economies and the state government. For the longest time, it was easy to ignore a growing body of science and ever-increasing damage that was being caused by the industry. But now it's serious — and the denial is over.

"For us to ignore this problem, or industry to ignore this problem — that wasn't an option," said Baker, adding industry has also acknowledged the problem and is working on solutions.

"They want this problem to go away as bad as anybody else does because it's a black eye for them as well."

Gail Atkinson, a specialist in induced seismicity from Western University in London, Ont. led sessions on industry-induced earthquakes at the Seismological Society of America annual meeting in Reno, Nev., on April 20. (Terry Reith/CBC)

Baker describes the task ahead of him as "Herculean." He says that earthquakes caused by the oil and gas industry threaten not just homes and residential buildings, but critical infrastructure like the oil terminal at Cushing, which is the largest pipeline and oil storage facility in the United States.

"We started having earthquakes in the Cushing area," Baker said, "so there is concern."

It happened in 2014 when a new injection well opened near the town. There was enough concern that the well was shut down and the earthquakes stopped.

When new wells were drilled, the earthquakes started again. When three of them were capped, the earthquakes subsided, but not entirely.

Tim Baker, Oklahoma's state oil and gas regulator, says the link between fracking related activities and earthquakes is undeniable. (Terry Reith/CBC)

Based on its observations at Cushing, the state felt that simply modifying the wells and shutting down those that were considered too deep would be a solution. About 200 of the deeper wells were plugged.

Baker says there was "some success, but it was measured. It wasn't enough to solve the problem."

Now the state is phasing in a plan that will reduce the amount of waste water injected into more than 600 wells by up to 40 per cent.

The plan is in its early stages and earthquakes in Oklahoma are down, according to Baker, but he admits it's hard to determine if that's because of regulation or the fact the downturn in oil prices has curtailed drilling substantially.

Less doubt

The meeting in Reno last week drew nearly 700 seismologists and other experts from government, academia and industry.

During a full-day session on induced earthquakes, 29 scientists presented new research in a series of 15-minute oral presentations, while 35 researchers presented new findings in poster presentations.

The area around the Enbridge pipelines tank farm at Cushing, Okla., began to get earthquakes when fracking disposal wells were drilled. (Terry Reith/CBC)

The cumulative volume of research leaves little doubt about the link between fracking and earthquakes. One point of debate that did emerge is the significant difference between how the quakes are caused in Canada and the U.S.

In Oklahoma, the earthquakes are blamed on the industry practice of injecting waste water from oil production into wells dug deep into the ground. This causes changes in underground pressure and deep underground faults to slip, resulting in earthquakes.

In Canada, the direct action of fracking is blamed, as less water is used and injected back into the ground.

University of Calgary seismologist David Eaton says in the past six years, 90 per cent of earthquakes larger than magnitude three taking place in the Western Canada Sedimentary Basin can be linked to fracking or waste water disposal. The vast majority — 62 per cent — are directly linked to fracking.

He believes that like those in Oklahoma, the earthquakes are being caused by changes in pressure underground.

Atkinson believes part of the difference between Canadian and U.S. quakes can be attributed to different geology.

"There's evidence that the types of formations that are being explored have differences that would explain why hydraulic fracturing is so much more likely to induce seismicity in Western Canada than it is in Oklahoma."

David Eaton of the University of Calgary was among the Canadians presenting new research on links between fracking activities and earthquakes. (Terry Reith/CBC)

Another key difference is the earthquakes in Canada have so far caused very little damage.

Part of the reason may be that the larger Canadian quakes have happened in largely isolated areas, where the Oklahoma quakes have affected highly populated areas.

Atkinson warns that Canadians shouldn't get complacent.

"As much as it would be nice to say we've had magnitude four and a half earthquakes in Western Canada and we haven't seen any damage yet and therefore we'll never see any damage, I don't think you can reach that conclusion."

Canadian researchers are now turning their sights toward learning how to better predict which fracking operations might cause earthquakes.

"The first level of mitigation is avoidance. So if we know that there's a problem and we can map areas where it's more problematic ... then what we need to do is design strategies that would minimize risk within those areas," says Eaton.

Putting an end to fracking isn't on the table on either side of the border. Regulators in Oklahoma, B.C. and Alberta are instead looking toward regulations and changing industry practices as a means to mitigate the damage.

But no one really knows if that will help stop the shaking, and no one even knows whether an end to fracking altogether would be enough to completely stop the earthquakes.