Beaufort Sea more earthquake prone than thought

New research has led seismologists to increase the earthquake hazard rating by up to five times along the Arctic coast and up to two times beneath the Beaufort Sea itself.

Earthquake hazard rating in the area is in the process of going from 'moderate low' to moderate'

New research suggests there’s greater earthquake hazard in the Beaufort Sea and along its coast than previously thought. The area is being targeted for offshore oil exploration and a deep sea port.

The discovery came in part from GPS data that shows land in the central and southern Yukon is moving north toward the Beaufort.

Studies of earthquake activity to the east and west parts of the Beaufort support that theory.

“Based on the size of that area where we think the collision would be taking place, it would allow for an earthquake up to a size of 7.8 [on the Richter scale],” says John Cassidy, an earthquake seismologist with Natural Resources Canada.

The earthquake hazard rating in the area is in the process of being moved from “moderate low” to “moderate.”

To put that in perspective, in Victoria, which has one of the highest earthquake ratings in the country, there’s a 30 per cent chance that people will experience buildings shaking in the next 50 years. In Paulatuk, there’s a five per cent chance of a similar event.

“The largest earthquake ever recorded in the Beaufort Sea region is a magnitude 6.5 earthquake back in 1920,” Cassidy says. “Typically we see a few earthquakes in the magnitude of 3 to 4 range each year.”

Earthquakes of magnitudes less than five are unlikely to cause damage.

The new earthquake hazard rating could have an engineering impact on any future oil and gas exploration in the area. It could also mean earthquake preparedness plays a larger role in the environmental assessment process for oil and gas projects, or any construction in the region.

Seismologists will further investigate the earthquake history of the Beaufort Sea this summer.

"If one of these collisional type earthquakes has occurred in the past — hundreds or thousands of years ago — then it may have generated a tsunami, and we plan to look for evidence of any tsunami that would have been generated by that type of earthquake,” Cassidy says.

Scientists will be examining layers of earth below the surface of the Mackenzie Delta region from mid-July to mid-August.