Earthquakes in Alberta to become more frequent and stronger, expert says

Tremors caused by industrial activity will become more frequent and large enough to cause significant damage in the future,warns an expert on human-caused earthquakes.

"As we generate more and more earthquakes, we expect that some of them are going to be larger," saidGail Atkinson, who studies induced seismic activity at Western University in London, Ontario.

"So this is another example of the potential for oil and gas activity to generate some larger earthquakes which could become damaging."

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Induced earthquakes are closer to the surface, so the shaking is more intense than a natural earthquake which happens many kilometres further below, said Gail Atkinson, who studies induced seismic activity at Western University in London, Ontario.

An induced earthquake that registers 4.0 on the Richter scale can shake the ground more than a natural 5.0 magnitude quake, she said.

The study of induced quakes is relatively new, Atkinson said.

"We're seeing a lot more earthquakes and we are really just getting a handle on their characteristics.

"A lot of things we know now weren't known two or three years ago."

On Tuesday morning, a magnitude 4.8 quake hit the Fox Creek area in northwest Alberta, the strongest ever recorded in Alberta and perhapsthe largest induced quake in Canada's history.

Repsol Oil and Gas confirmed the seismic event and said it was conducting hydraulic fracturing operations at the time it happened.

The Alberta Energy Regulator ordered Repsol to shut down the site until the quake can be investigated.

While people in the Fox Creek area noticed the quake few thought much of it.

Next quake could be stronger

But next time could be different, Atkinson said.

"They're so close to the surface, so a relatively moderate earthquake is much closer to you than it would be if it was natural earthquake.

"That means the ground movements on the surface are going to be much stronger proportionate to the magnitude."

Induced quakes occur between two and four kilometres below the surface, while natural quakes are much deeper, up to 15 km.

Atkinson also notes that Alberta is not a naturally geologically active region so buildings and other infrastructure are not built with quakes in mind as the Pacific Coast, so quakes may be more hazardous.

Howeverit's the damage that induced quakes can wreak underground that worries Jim Ahn, the mayor of Fox Creek.

Ahn worries a quake stronger than Tuesday's could damage the town's water supply.

"There's always concern it could be larger and we could hit the big one," said Jim Ahn. "I don't know what kind of damage it would do, especially to our aquifers."

While earthquakes are worrisome, Ahn acknowledges oil and gas accounts for almost all employment in the area.

"We rely on the oil patch," he said. "We're a resource driven town. We have oil and gas along with forestry. That's really a sense of why Fox Creek exists."