Strange Weather in Southern Ontario
On Tuesday, January 27th, at 11pm, it was around -12C in Orillia. After weeks of consistent, heavy snowfall, it would be intuitive to assume any loud rumbling noises outside your house at that time of night would more than likely be from a snow plow diligently clearing the streets.
Instead, a 3.7 (some say 4.1) magnitude earthquake hit. Fear not, Thunder Bay readers. None were harmed. But many were rattled, with reports saying shaking was felt by around 2,600 people across southern Ontario, some of whom were hundreds of kilometers away from the epicenter.
While earthquakes aren't generally considered weather events, there is a weather-related "frost quake", where water deep within the earth's crust freezes and expands, causing the ground to crack and "pop". However, experts say that wasn't what happened here.
In fact, CBC reported that in the last 25 years, the area has experienced two other "classic" earthquakes of similar magnitude. Almost a hundred years ago now, the region was hit with a historically-high 5.5 magnitude earthquake. Why?
A seismologist who spoke to CBC commented that this region does not generally incur seismic activity, due to it being an intraplate region towards the middle of the North American plate. Plate boundaries, rather than centers, tend to be subject to the most deformation (when tectonic forces accumulate in the crust, changing the surface of the earth), and in turn experience substantially more earthquake activities than plate interiors (or intraplate regions).
Intraplate earthquakes are poorly understood. Many researchers believe they are caused by old rifts (places where the crust of the earth and the upper portion of the earth's mantle, the lithosphere, become pulled apart) reactivating. However, why these old rifts would reactivate is still a subject of debate.
Southern Ontario often experiences periodic earthquakes with similar magnitude to last Tuesday's, but these have not been severe enough to make international headlines.
The same cannot exactly be said for tornadoes. In 2021, Barrie was hit with a devastating tornado that boasted 210km/hr winds, destroyed over a hundred homes along a 12 kilometer path, and resulted in over 2,200 insurance claims.
Canada ranks high globally for tornado occurrences, and Ontario is actually considered to be the leading province for tornadoes per year, with the most activity during the warm, summer months. You might be wondering - why does Ontario rank so high? Isn't Saskatchewan our biggest offender for tornadoes? While this seems to have been true once, there has been a clear pattern in recent research showing that our "tornado alley" is moving eastwards, causing an increase in activity in Ontario and Quebec.
While it's nice that these tornadoes are generally less threatening in the winter, Eastern Canada (Ontario included) does have a bad track record for its nasty ice storms. Many will remember the immense damage incurred by last spring's freezing rain event, which incapacitated powerlines and caused massive trees to collapse, both contributing to major power outages across the province that lasted several days.
Those who have seen many winters may recall the "January 1998 North American Ice Storm" that resulted in 34 fatalities, shutdowns of major cities (like Ottawa and Montreal), and, in some areas, no electricity for months.
A historically severe event, this, and other freezing rain storms, are caused by cold air damming, which happens when warm air masses (usually heading north from the Mississippi Valley), overrun more shallow layers of cold air.
In these circumstances, snow melts into rain upon coming into contact with that warm layer of air, and then freezes again once it hits the cold air layer below. The most hazardous form of freezing rain occurs when the cold air layer isn't very thick, and, rather than turn into ice pellets, the rain simply freezes on contact with the ground. Yikes!
In our constantly changing environment, keeping your eyes peeled for unusual weather systems and paying attention to alerts can make some of these strange surprises a lot less unexpected.
If you're interested, you can always keep track of weather patterns yourself, with some simple equipment, or by monitoring governmental databases. Perhaps, in a few years, you'll find some fascinating trends that might help to give the unusual an explanation, or, at least, a theory.