Cascadia Isn't a Question of If — It's a Question of When

Understanding Earthquake Risk on Canada's West Coast

Recent earthquake activity across South America, Alaska, and Japan has once again drawn global attention to seismic hazards around the Pacific Ring of Fire.

At nearly the same time, researchers studying Southern California reported new findings suggesting that stress has continued to accumulate along several major fault systems over centuries. While these studies focus on California, they also remind us of an important reality much closer to home.

British Columbia sits on one of the most closely monitored seismic zones in North America.

The Cascadia Subduction Zone

Off the west coast of Vancouver Island lies the Cascadia Subduction Zone (CSZ)—a plate boundary stretching roughly 1,000 kilometres from Northern California through Oregon and Washington to Vancouver Island.

Here, the Juan de Fuca Plate slowly slides beneath the North American Plate.

The movement is almost invisible.

Only a few centimetres each year.

But over hundreds of years, enormous amounts of energy can accumulate beneath the Earth's surface.

When that energy is finally released, the result may be a megathrust earthquake capable of producing both strong ground shaking and a Pacific tsunami.

Geologists know this has happened before.

The question is not whether Cascadia can produce another major earthquake.

It is when.

Why Vancouver Should Pay Attention

Unlike California's famous strike-slip faults, Cascadia presents a different type of hazard.

A large offshore earthquake could affect much more than shaking alone.

Potential impacts may include:

• Extended power outages
• Damaged transportation infrastructure
• Temporary communication failures
• Supply chain disruptions
• Localized flooding in coastal areas
• Possible tsunami warnings for parts of the coast

Many of these secondary effects could last far longer than the earthquake itself.

For most households, the greatest challenge may not be the shaking.

It may be the days that follow.

Richmond and Liquefaction

Certain communities face additional geological challenges.

Richmond, for example, is largely built on soft river delta sediments deposited by the Fraser River.

During intense shaking, water-saturated sandy soils can temporarily lose strength—a phenomenon known as soil liquefaction.

Buildings are not guaranteed to collapse, but roads, underground utilities, pipelines, and foundations may experience significant movement.

Modern engineering greatly reduces these risks for newer construction.

However, liquefaction remains an important planning consideration throughout the Lower Mainland.

High-Rise Buildings

Many residents wonder whether high-rise buildings are safe during earthquakes.

Modern towers are intentionally designed to sway.

Controlled movement allows a building to absorb seismic energy instead of resisting it rigidly.

This movement can feel dramatic to occupants, especially on upper floors, but it is part of the engineering design.

Older buildings, however, may not meet today's seismic standards and often require additional retrofitting.

The First 72 Hours

Emergency management agencies across Canada consistently recommend that households prepare to remain self-sufficient for at least 72 hours following a major disaster.

During this period, emergency responders will naturally prioritize life-threatening situations first.

Households may temporarily lose access to electricity, clean water, fuel, grocery stores, or transportation.

Basic preparedness significantly reduces stress during this critical window.

Every emergency kit should include:

• Drinking water
• Shelf-stable food
• Flashlights
• Batteries
• First aid supplies
• Prescription medications
• Emergency radio
• Portable power bank
• Copies of important documents

Preparedness is not about expecting disaster.

It is about reducing uncertainty.

Preparedness Is Confidence

No one can predict the exact day of the next major earthquake.

Fortunately, effective preparedness does not require predicting the future.

Small steps taken today—building an emergency kit, creating a family communication plan, and storing several days of essential supplies—can make a meaningful difference when unexpected events occur.

Preparedness isn't driven by fear.

It is built on resilience.

Prepared Today. Ready Tomorrow.