A Brief Overview: Earthquakes
The earth is comprised of three layers – the crust, the mantle, and the core. The crust is the outer layer which accounts for 1% of the earth’s volume. The earth’s crust consists of sedimentary, igneous, and metamorphic rocks. The inner layer of the earth is known as the mantle, which accounts for 84% of the earth’s volume and is composed of rocks that contain minerals such as silicates, iron, aluminum, calcium, sodium, and potassium. The earth’s core is the hottest part with temperatures reaching over 5000°C (Geological Survey Ireland, 2022). It is theorized that tectonic activity occurs because of convection currents from the magma in the mantle, which then creates currents that move the tectonic plates (Seraphin, et al., 2022). The tectonic plates are composed of large rocks from the lithosphere which is made up of the crust and the upper mantle. There are seven major and eight minor tectonic plates, with the largest plates being the Antarctic, Eurasia, and North American plates (California Earthquake Society, 2020). The tectonic plates are constantly moving, with the North American plate moving 3.2 centimetres per year (Pacific Northwest Seismic Network, 1999). Tectonic activity has led to the creation of volcanoes, mountains, and ocean trenches across the globe. Tectonic activity accounts for 97% of earthquakes in the world. Approximately 5000 earthquakes occur in Canada each year, but only a small number of earthquakes reach a high enough magnitude to be felt (3.5 or greater) (Government of Canada, 2021).
What is the Earthquake Risk in Canada?
The coast of British Columbia is a high-risk zone for experiencing a major earthquake. The St. Lawrence and Ottawa River valleys and the territories are also vulnerable to earthquakes (Government of Canada, 2015). Here in Eastern Ontario, there is an average of approximately 450 earthquakes per year, but they are small and often undetectable – with only 25 earthquakes annually being felt by the communities and surrounding areas (Government of Canada, 2021). Eastern Ontario is part of the stable interior of the North American plate. Earthquakes here are often due to weak crust not because of the fault lines located at the plate boundaries (Government of Canada, 2021).
What Earthquake Zone is Ottawa Located Within?
Ottawa is in the Western Quebec Seismic zone. On June 23rd, 2010, a 5.0 magnitude earthquake occurred in Val-des-Bois, Quebec, located approximately 60 kilometres from Ottawa. The earthquake was one of the strongest experienced in over 200 years in this region (Natural Resources, Canada, 2010).
Earthquake Preparedness Tips
It is important to be prepared for an earthquake before it strikes. To prepare your home for an earthquake, start by securing large objects such as furniture, appliances, and televisions so that they don’t tip over. Heavy and breakable items should be stored on lower shelves in case they fall during the earthquake. Always have an emergency plan and a 72-emergency kit with items such as non-perishable food, water, batteries, radio, first aid supplies, and medications. More information about how to create an emergency plan and kit can be found here.
What to Do During an Earthquake?
During an earthquake, you should immediately drop, cover, and hold on until it is safe to evacuate the building. Drop to the ground and find cover under a piece of furniture or by covering your head and neck. If you are unable to drop to the ground, shield your head and neck from debris. If you use a mobility device, lock your mobility device in place and shield your head and neck. It is important to stay away from doors and windows. If you are not indoors when the earthquake strikes, stay away from buildings. If you are in a vehicle, stay in the vehicle and pull over to the side of the road (FEMA, 2021). If you are in the tunnels, drop, cover, and hold on, until it is safe to evacuate through the nearest safe exit.
References
California Earthquake Society. (2020, August 31). Understanding plate tectonic theory.
https://www.earthquakeauthority.com/Blog/2020/Understanding-Plate-Tectonic-Theory
FEMA. (2021, August 18). Earthquakes. Plan Ahead for Disasters | Ready.gov.
https://www.ready.gov/earthquakes
Geological Survey Ireland. (2022). The Earth’s Structure.
https://www.gsi.ie/en-ie/education/our-planet-earth/Pages/The-Earth-structure.aspx
Government of Canada. (2021, March 6). Earthquake zones in Eastern Canada.
https://www.seismescanada.rncan.gc.ca/zones/eastcan-en.php
Natural Resources Canada. (2010). The 2010 Val-des-Bois Quebec earthquake.
https://www.seismescanada.rncan.gc.ca/pprs-pprp/pubs/GF-GI/GEOFACT_ValdesBois2010.pdf
Pacific Northwest Seismic Network. (n.d.). Plate Tectonics. https://pnsn.org/outreach/about-earthquakes/plate-tectonics
Seraphin, D., Philippoff, K., Pottenger, J., Kaupp, F. M., Lurie, L., H, M., D, L., & Baumgartner, E. (2022). Continental Movement by Plate Tectonics. EXPLORING OUR FLUID EARTH Teaching Science as Inquiry.
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