Manitoba is not a common place to encounter earthquakes, due to our distance from any tectonic plate edges, where earthquakes are more common. A rare occurrence happened in August, when two earthquakes happened north of Brandon, within 24 hours. Normally this would be interesting, but what makes it intriguing is that local geologists aren’t completely certain what caused them. This raises questions about the future of earthquakes in Manitoba.
The first earthquake took place on Aug. 11, 2021, at 4:34 a.m. It was felt in the nearest town of Binscarth, around 15 kilometres away from the epicenter. It was 4.2 in magnitude measured on the Richter scale, which is barely noticeable unless you were to stand still. Many reported seeing buildings shaking, or that their bed was shaking as they were trying to sleep. It’s quite possible that if it had occurred during the day, very few people would have noticed.
The second earthquake occurred later that day at 8:25 p.m. It was of a similar magnitude, measuring in at 4.0. The epicenter was in the same spot as the previous one, and once again, the people of Binscarth noticed it. There have not been any reports of damage after these earthquakes, but the cause of these earthquakes would prove to be messy to solve.
When looking into the origin of these earthquakes, many geologists said it was simply caused by a potash deposit, the most common cause of earthquakes in Manitoba. At first, it seemed as though this was the cause, but after a deeper investigation, many geologists found evidence to support the idea that the earthquake was caused by a pre-Cambrian basement.
A pre-Cambrian basement is simply referring to the layers of rocks that were once at the surface during the pre-Cambrian era. These rocks are now covered by new rock layers that were formed or placed on top of the basement. Due to its age, the pressure on it and other factors, the basement has and will continue to break down.
This theory has gained plenty of support. Simon Pattison is a professor of geology at Brandon University who also supports this theory. He stated in an interview that at first, he, like many others, thought it was simply a potash deposit that started this earthquake, but then he looked at the data and decided that it would be worth diving deeper into. He claimed that in all his time working at the university, he has never seen such a strong earthquake in Manitoba that originated from so deep below the surface.
This analysis leads to several new questions that stretch far beyond the one incident. Will Manitobans have to begin preparing for earthquakes in the future? Will they begin to affect major cities? Will they increase in magnitude? These questions can be applied to neighbouring provinces, which commonly have earthquakes that affect towns near the provincial borders. All these concerns rely on whether it’s common to have earthquakes in those regions.
According to Volcano Discovery, mild earthquakes happen in and around Manitoba every couple of years. Most tend to stay in the range of 2.0 magnitude, but two years ago there was an earthquake on the Saskatchewan border that was 4.1 in magnitude, a 4.1 10 years ago, and a 4.4 11 years ago, all of which are very similar range to the Binscarth earthquakes. This shows that it’s not uncommon for earthquakes of that magnitude to occur in the region, making the Binscarth earthquakes less unusual than first thought, making them less concerning overall.
» Lowdin Lourenco is a Grade 10 student at École secondaire Neelin High School.