Earthquakes in Canada... What are the Chances?
Wednesday, July 22, 2015
It may surprise you to learn that about 4,000 earthquakes are recorded in Canada each year. There are 1,000 recorded annually in Western Canada alone. Most of them are small and barely detectable. But every year, there are more than 50 earthquakes that are strong enough to be felt by Canadians.
Over the past 300 years, there have been 24 significant earthquakes in Canada, which were concentrated in two regions: off the west coast of B.C., and in the area encompassing southern Quebec and southeastern Ontario. Although these two seismic source zones cover a small fraction of Canadian land area, they impact about 40 percent of our national population.
What are the chances of a significant earthquake happening in Canada again?
Western Canada is the most seismically active region in our country. The most seismic of these regions is offshore, west of Vancouver Island. More than 100 earthquakes with a magnitude of 5 or greater have occurred here in the past 70 years.
According to government studies, there is a 30 percent chance in the next 50 years that an earthquake strong enough to cause significant damage will strike the coastal area of British Columbia – including Victoria and Vancouver.
In the southeast, the slow movement of the North American plate at a few centimetres per year creates sufficient stresses to cause earthquakes along faults or zones of weakness (such as along the St. Lawrence and Ottawa valleys and the Atlantic seaboard).
Because of this, there is a 5 to 15 percent chance in the next 50 years that a strong earthquake will occur in the region from the St. Lawrence River Valley to the Ottawa Valley – including Quebec City, Montreal and Ottawa.
Whole lot of shaking going on
Unlike natural disasters like hurricanes, earthquakes don’t have a specific season in which they occur. Earthquakes do not come with a warning, and they can happen at any time.
An earthquake is usually caused when rock deep underground suddenly breaks along a fault. Stress builds up and the two sides of the fault slip against each other, releasing energy in waves that travel through the earth's crust and cause the earth to shake.
The way an earthquake feels depends on where you are when it occurs. If you happen to be near the source of an earthquake, known as the epicentre, you will feel a sudden jolt followed quickly by a strong shaking or rolling feeling like you’re on a ship in rough water. That may continue for a few seconds or even a couple of minutes if it’s a significant event.
If you’re far from the source, you may feel a light trembling, hear clinking glasses, and notice that the pictures hanging on the wall are slightly askew.
After the initial earthquake, there are aftershocks, which can feel a lot like an earthquake, but they are not as strong as the first one. The larger the earthquake, the bigger and more numerous the aftershocks. The biggest usually hit within days of the original earthquake and trail off in days or months.
Contrary to what many believe, the earth does not open up and swallow everything that once stood on it. The ground on the two sides of the fault slide past each other, they do not pull apart. Shallow crevasses may form during an earthquake but they do not gape open.
Can Canadian homes withstand earthquakes?
There are some variables that determine how well your home will withstand the impact of an earthquake such as how close you are to the epicentre, or when your home was built.
Modern homes must be built to national and provincial building standards, which help to minimize the possibility of a home collapsing in an earthquake. But an older building that is not upgraded to current building codes may be more vulnerable.
In general, Canadian homes are structurally sound and should be able to withstand vibrations generated by most earthquakes.
There may be some visible damage to your home such as cracks in the walls or in the masonry of brick walls and fireplaces. Vibrations may also cause ground settlement under a house, which can cause cracks in the basement or walls to warp.
Sometimes the shaking ground can cause substantial harm. A broken gas line may result in a fire. Or falling items and shattered glass can injure people.
Do you need earthquake insurance?
The Insurance Bureau of Canada (IBC) recently commissioned a study to determine the scale of losses possible in the event of a major earthquake. The study estimated the overall costs after a 9.0-magnitude earthquake in British Columbia at almost $75 billion. The study also estimated that a 7.1-magnitude earthquake in the Quebec City – Montreal – Ottawa corridor would cost Canadians almost $61 billion.
- If you live in or near a seismic source zone, considering earthquake insurance may be a smart decision. The cost of insurance will depend on where your home is and how it was built.
- Here are some things you need to know about earthquake insurance:
- Coverage for earthquake damage is not included in a standard home insurance policy but can be purchased as an add-on to your existing policy.
- Earthquake insurance covers the loss or damage to your property and its contents caused by the shaking of the earth.
- Earthquake insurance is subject to a higher deductible.
- If an earthquake breaks a gas main and starts a fire, the resulting fire damage would likely be covered under a standard home insurance policy. Your coverage will depend on the legislation in your province or territory.
In certain circumstances, homeowners who are unable to return to their home as a result of insurable damage are entitled to additional living expenses.
What to do when the earth starts shaking
Wherever you are when an earthquake starts, take cover immediately. The biggest threat during a major earthquake is falling debris such as light fixtures, ceiling plaster, or chimneys that can fall outside or even through the roof of your home.
- Move to a nearby safe place and stay there until the shaking stops. Keep these safety tips in mind:
- Try to stay calm – don’t panic.
- If you’re indoors, stay indoors. Take cover under a heavy table, desk or other solid furniture. If this type of furniture is not available, go to a hallway, a corner or an archway. Avoid doorways and areas near windows.
- If you’re outdoors, stay clear of buildings, tall fireplaces on buildings and power lines. Keep a lookout for falling debris.
- If you are in a wheelchair, lock the wheels and protect the back of your head and neck.
- Avoid elevators. They may be damaged or the power may fail. If you’re in an elevator when an earthquake starts, get out as soon as possible.
- If you’re in a vehicle, drive away from any buildings. If you’re on a bridge, drive off the bridge or overpass. Pull over to the side of the road and stop. Stay inside your car. If possible, listen to your radio for instructions from emergency officials.
After an earthquake:
- Try to remain calm.
- If you’re able, help the injured, if any.
- Speak calmly with family members, especially children.
- If it is safe, check your home for structural damage and any hazards that could be a threat to you and your family.
- Secure your home against intruders.
- Do not shut off utilities unless there is damage to them.
- Check gas lines. Don’t light matches or turn on light switches unless you are sure there are no gas leaks or flammable liquids in the area.
- Don’t flush the toilet if you suspect that nearby sewer lines may be broken.
- Be careful around debris, especially broken glass.
- Place “HELP” signs in the window if you need assistance.
- Stay away from downed power lines.
- Stay away from any waterfront areas because there is a threat of large waves and currents after an earthquake.
- Stay tuned to the radio for emergency instructions.
- Use the telephone only in an emergency.
- Do not enter damaged buildings.
You may be without help for 72 hours or more, so it’s a good idea to have an emergency kit packed and ready to go in the event of an earthquake or other disaster.
Earthquakes do occur in Canada. While most earthquakes are minor and hardly noticeable, there is the potential for significant earthquakes to hit our country and cause considerable damage. Understanding where they can happen, and knowing what to do in the event of an earthquake is the best way to ensure everyone’s safety.
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