By Matthew Casey
It was a much unexpected event today that had many people talking around the dinner table across eastern Canada. A magnitude 5.0 earthquake occurred in Quebec just 50 kilometres north of the city of Ottawa and was felt as far away as Windsor in southern Ontario. Damage from this event was minor with the most significant damage being a collapsed bridge from a causeway in Bowman, Quebec. Although it may be an occurrence that is not common around this part of the country, it is still a startling reminder that Central Canada is indeed on a fault zone and can be subjected to seismic activity.
When most think of a major earthquake prone area in North America the place that most likely comes to mind is the West coast. But the quake that occurred today has drawn attention to the not often talked about fault lines that exist in Eastern and Central Canada. The quake that occurred on June 23 was centered in the Western Quebec Seismic zone which is an area that encompasses a vast amount of land from the Ottawa Valley from Montreal to Temiscaming, Quebec, as well as the Laurentians and Eastern Ontario.
While this area seems not to be prone to frequent seismic events, there have been some notable quakes in the past. Records from Natural Resources Canada indicate that between the years 1980 and 2000 sixteen earthquakes in this seismic zone have reached or exceeded 4.0 on the Richter scale. The area has also seen more significant quakes in the past that include a 5.8 magnitude quake in 1732 that rocked the city of Montreal and caused significant damage. Another more severe event occurred in 1935 when a magnitude 6.2 earthquake shook the area of Temiscaming, Quebec, a sparsely populated area about 194 kilometres east of Sudbury, Ontario. This quake was followed by another significant one nine years later in 1944 which took place between Cornwall, Ontario and Massena, NY. The magnitude 5.6 quake caused significant damage estimated at two million dollars at the time.
What the quake of June 23, 2010 brings to light is how unprepared the eastern portion of Canada may be to deal with such an event. As history shows there have been stronger quakes than this one and had a stronger one occurred the area may not have been entirely prepared to deal with any damage that would be caused by a more severe event. Today’s event showed that many were caught by surprise because this sort of thing is not something that is thought to happen in this part of the country.
Dr. Arsalan Mohajer, a professor of geology at the University of Toronto said in an interview with the Globe and Mail that there are faults that run across Ontario and Quebec that could be potentially disastrous for this area if it is not prepared for a more violent quake. Dr. Mohajer says that there is a threatening fault that runs along the St. Lawrence River valley that could affect many areas around Montreal, Cornwall and Quebec City. He also mentions that there is another similar fault that is located in the Niagara-Pickering area of Ontario that is in his words “inconveniently close to Toronto and safety-related nuclear facilities east of the city.”
According Dr. Mohajer the western half of Canada is prepared to deal with a major quake by investing in stricter building codes and teaching children what to do in an earthquake. However, he says that eastern half of the country doesn’t expect events like this and is therefore not prepared to deal with them in the same way.
But as history shows, the amount of major activity in this seismic area is fairly low. Dr. Mohajer explained that the area is a “weak zone” that tends to see low to moderate activity. Most quakes that occur in other areas are the result of two plate boundaries pushing together. However the event that occurred today was what is known as an “intraplate quake” which occurs within the plate as a result of pressure building up from constant pushing at the boundaries.
If nothing else, the earthquake of June 23 should be an eye opener that no one should forget that this area is not immune to these types of natural disasters. Hopefully this will cause communities in Eastern and Central Canada to review their preparedness plans to ensure that they have proper plans in place to deal with a more significant event should one occur in the future.
Natural Resources Canada
The Globe and Mail