Earthquakes in Montreal? No way!

Published: November 12, 2021

by Meghomita Das, Science & Policy Exchange

In the early morning hours of May 17, 2021, Montrealers across the island woke up with a jolt to start their day.

A small 3.8 magnitude earthquake struck about 70km northeast of Montreal. The shaking was felt in parts of Laval, Saint-Bruno-de-Montarville, and Notre-Dame-de-Grace (NDG).

Even though this was a small magnitude earthquake (on the grand scale of earthquake magnitudes), it wasn’t the first one to hit Quebec and it definitely won’t be the last. Earthquakes pose huge threats to communities living in earthquake-prone areas and cause billion-dollar losses to the economy. Canada records over 4000 earthquakes each year, approximately 11 per day. Fortunately, most of these earthquakes are not strong enough for us to feel them. For people living on the west coast of Canada, strong earthquakes are a reality and a big one is long overdue. However, eastern Canada holds its own seismic surprises. Earthquakes Canada, which is affiliated with Natural Resources Canada, monitors earthquake activity across Canada and determines the ground shaking potential of various locations across the country during an earthquake. The agency categorizes southwestern Quebec under the “High to Moderately High” seismic hazard zone, with a thirty percent chance of significant damage every 50 years.

Why does Montreal experience earthquakes?

The city of Montreal sits between two active earthquake-producing zones: the Charlevoix-Kamouraska Seismic Zone (CSZ) and the Western Quebec Seismic Zone (WQZ). The Charlevoix zone follows the St Lawrence river, close to Quebec City and the Western Quebec zone covers the vast land from Montreal to Temiscaming, along the Ottawa Valley. These two zones have produced some high magnitude earthquakes in the historic past. The largest earthquake recorded in Quebec is the 1925 magnitude 6.2 earthquake in Charlevoix. The largest earthquake recorded within the Western Quebec Seismic Zone was a magnitude 6.2 that hit the area of Temiscaming, along the upper Ottawa River. Prior to the use of seismometers, earthquake stories can be found within the first nation’s oral traditions with reports describing the collapse of houses, destruction of villages, and intense shaking of the ground. These historical events along with the recently felt earthquakes alert us to the reality that Montreal is indeed on shaky grounds.

How can we prepare for earthquakes?

As earthquakes cannot be predicted and cannot be controlled, preparing for earthquakes requires a collective effort, both at the governance level and at the community level. At the governance level, the focus should be directed at infrastructure needs and effective disaster communication plans that alert the communities at risk. Updating building codes, retrofitting old buildings to stabilize them, and conducting regular emergency drills with designated emergency evacuation paths is a good starting point. Lack of robust building structures, both residential and commercial, could cause severe damages even when the earthquake magnitude is low. For an unprepared city like Montreal, with a growing population and a large percentage of outdated building infrastructure sitting in the middle of earthquake-prone zones, even a small magnitude earthquake can wreak severe havoc and cause massive damage to lives and property. This fact came to reality in 1732 when a magnitude 5.8 earthquake shook the city of Montreal causing significant damages to chimneys, walls, and around three hundred houses. Another way to make earthquake-safe cities is the implementation of earthquake early warning systems (EEW) where earthquakes are rapidly detected and real-time alerts are sent to the citizens and prompt them to take necessary actions. Natural Resources Canada is currently developing such a system for Canada.

Epicentral earthquake locations (colored circles) in eastern Canada in five-year intervals starting in 1985. The size of the circles is scaled by their magnitudes. Only earthquakes reported as felt are shown. Animation by Dr. Andres Peña-Castro, McGill University, using data from Natural Resources Canada (NRCan)

At the community level, earthquake preparedness comes down to effective communication between the government authorities and the community. Earthquakes Canada provides an extensive list of best practices one can implement in order to be ready for an earthquake. These practices are not that different from preparing for any other natural disaster like floods or hurricanes, but it does require nationwide implementation. Getting an earthquake kit ready, insuring your property, testing the land for seismic hazards, participating in emergency drills at schools and offices, and knowing what to do during an earthquake are all effective strategies that can reduce the panic levels during the earthquake and provide valuable time to get to safety and thus save lives. Several cities across Canada instituted mock emergency preparedness campaigns such as the Great Shakeout or La Grande Secousse to help with what to do during an earthquake and how to prepare for it. These campaigns are yearly initiatives directed to participants from across the globe, and they promote three simple actions: Drop under a table, Cover your head, and Hold on to the table.

As the United States Geological Survey states, we cannot forecast earthquakes or state conclusively when the next big one will strike. While we wait for it, however, we need government instituted policies and more awareness about such disasters that will safeguard our vulnerable cities and save countless lives.