Moderate quake hits Yorkton area

“With an earthquake of this magnitude unless you are very close to the epicentre, you might not even be woken up by it.”
— Michal Kolaj, a seismologist with Natural Resources Canada

It was not all that significant and it happened really early in the morning, but some people around the Yorkton area felt the earth move Monday.

The earthquake hit 32 kilometres southest of Yorkton at 4:40 a.m. September 5 at a depth of approximately 10 kilometres. It registered 3.8 on the Richter Scale. Quakes of that magnitude at similar depth can shake objects on tables and shelves but rarely cause damage. Authorities received no reports of damage or injury from the Yorkton quake, although SaskPower reported one of its substations may have been affected resulting in a two-hour power outage for rural customers in the Melville and Esterhazy areas.

Michal Kolaj, a seismologist with Natural Resources Canada (NRC), said by Tuesday morning the ministry had received 20 reports from people who claimed to have felt the quake. He estimated that is probably a small percentage of those who potentially would have experienced it, although many may not have even recognized what it was.

“With an earthquake of this magnitude unless you are very close to the epicentre, you might not even be woken up by it,” he said.

The reports NRC did receive were mostly from Yorkton and Esterhazy and were pretty generic, Kolaj noted.

“We haven’t had anything that really sticks out for me,” he said.

Worldwide more than 100,000 quakes of similar intensity are recorded every year, but they are relatively rare in the Yorkton area. That is because the city lies on top of the western part of the North American Craton, a huge chunk of ancient continental crust that underlies most of Canada and the United States from Alberta to Labrador and from the Canadian Arctic Archipelago to Texas. This mass of rock has been relatively stable for roughly 600 million years.

The Yorkton region has experienced 11 similar earthquakes since 1981. The last, a 3.1 magnitude event, was in 2014. The largest recorded earthquake in Saskatchewan history occurred in 1909 near Regina. It measured 5.3 and was felt as far north as Saskatoon, as far east as Winnipeg and into eastern Montana. Earthquakes of that magnitude are capable of causing minor damage.

The probability of a major Earthquake hitting Saskatchewan—up to around 7.0, which could cause serious damage and injury—is not zero, but is highly unlikely.

It is too early to say whether this week’s local event was entirely natural or aided by human activity, such as mining, although its proximity to the Esterhazy potash operation bears further investigation. In general terms, earthquakes occur when there is slippage along a fault line in rock.

The Richter Scale is a logarithmic representation designed to keep the numbers manageable. That means each integer on the scale is 10 times the intensity of the previous one. As such an 8.0 magnitude earthquake is 10 times 10 times 10 times 10 (10,000 times) stronger than a 4.0 event.