Tsunamis

A tsunami consists of a series of unusually large waves formed by a large-scale disturbance of water bodies. One of the primary causes of tsunamis is an earthquake, but tsunamis may also be triggered by landslides, volcanoes or explosions.

Did you know that a majority of the capital region’s coastline is quite elevated? This means that most people are safe from the risk of tsunami, or that anyone in a low-lying coastal areas does not need to travel far to reach safety. Generally, 4 metres or 13 feet elevation above sea level is considered a safe distance from the ocean on Southern Vancouver Island.

The risk of tsunami in the Capital Region: Depends on the earthquake source. 

Local Tsunami

A Local Tsunami is the main tsunami threat in the Capital Region and is associated with a “felt” earthquake.

A local tsunami could be generated by a large and strong earthquake, such as a Cascadia Subduction Zone earthquake off the Pacific Coast of Vancouver Island, sometimes referred to as “the big one.”

If you are near the ocean and feel a major earthquake, or if the motion makes it hard to stand, get to higher ground immediately - do not wait for an official warning. The shaking is your warning. Local government officials may not have enough time to issue a warning to residents in the event of tsunami created by a near-shore earthquake.

Stay Alert for natural warning signs of a tsunami such as:

  • Ground shaking
  • A sudden rise or fall of ocean level
  • A loud roaring noise coming from the ocean

Distant Tsunami

A Distant Tsunami may be associated with an earthquake from far away (like Alaska or Japan) and may not be felt. The risk of a distant tsunami is low for a majority of the region. 

Typically, there is time for an official warning and safe evacuation if deemed necessary by officials. Monitor local media and follow the instructions of local emergency officials.

How to Prepare 

  1. Know your risk
  2. Prepare an emergency kit
  3. Make an emergency plan

To learn more about tsunami risk and/or coastal flooding due to sea level rise and storm surge on our coast. Visit the Capital Region Coastal Flood Inundation Mapping Project completed in 2020 or contact your local emergency program.

Know your Zone

British Columbia's Tsunami Notification Zones

BC's coastal communities are divided into five tsunami notification zones. Each zone includes all islands and inlets within it.

Here in the Capital Region, you may find yourself in three of the five notification zones:

  • Zone C: Outer west coast of Vancouver Island including Port Renfrew
  • Zone D: Juan de Fuca Strait from Jordan River to Greater Victoria including the Saanich Peninsula
  • Zone E: Strait of Georgia including the Gulf Islands.

When tsunami warnings, watches or advisories are issued, they may make reference to these zones.

Tsunami Warnings, Advisories and Watches

Here in the capital region, there are two types of tsunamis, local and distant.

  1. Local Tsunami: will be associated with a "felt" earthquake.
  2. Distant Tsunami: will happen far away (like Japan or Alaska) and may not be felt.

If a Tsunami Warning, Advisory or Watch is issued for your area, monitor local media and follow the instructions of local emergency officials. These alerts may be updated, adjusted geographically, downgraded, or cancelled; and are initially normally based only on seismic information to provide the earliest possible alert.

Government officials may issue one of the following alerts:

Warning

  • Threat: Flood wave possible
  • Action: Full evacuation suggested (for areas at risk) 

A warning may be issued through public alert notification systems, radio and television broadcasts, or in the form of a siren in some communities. This is issued when a potential tsunami with significant widespread inundation is imminent or expected. Warnings:

  • alert the public that widespread, dangerous coastal flooding and powerful currents are possible and may continue for several hours
  • alert emergency management officials to take actions like the evacuation of low-lying coastal areas, and the repositioning of ships to deep waters when there is time to safely do so

In the event of an Immediate Tsunami Threat:

  • Move to higher ground, and go on foot if possible.
  • Follow the instructions of all emergency officials for your safety and the safety of those around you.

All areas of the coastline will not be impacted equally. Within very short distances, the effects of a tsunami may vary considerably and there could be dramatic differences in wave height and impact.

Advisory

  • Threat: Strong currents likely
  • Action: Stay away from the shore

This is issued due to the threat of a potential tsunami which may produce strong currents or waves dangerous to those in or near the water. Coastal regions historically prone to damage due to strong currents induced by tsunamis are at the greatest risk. Advisories:

  • may continue for several hours after the arrival of the initial wave, but significant widespread inundation is not expected for areas under an advisory
  • may result in local officials closing beaches, evacuating harbours and marinas, and the repositioning of ships to deep waters when there is time to safely do so

Watch:

  • Threat: Danger level not yet known
  • Action: Stay alert for more information

This is issued to alert emergency management officials and the public of an event which may later impact the watch area. Watches indicate emergency management officials and the public should prepare to take action.

During A tsunami

Never go to the coast to watch a tsunami.

Once at higher ground, stay there! Tsunami waves can last several hours and the first wave is not always the largest. Do not go back to tsunami hazard areas until instructed by local government officials.

Boats in Deep Water

If you are in deep water (at least 200 fathoms or 400 metres) when a tsunami warning is issued, stay there. Tsunami waves are small in deep water and probably won’t cause any damage. Stay tuned to your marine radio (Channel 16) for reports when it is safe to return to port.

Boats in Harbour

If you are still in the harbour when a tsunami warning is issued, you may have time to get to deep water. Listen to official estimated tsunami wave arrival times and plan safely. Do not motor your boat to open water if it is too close to the wave arrival time.

Moored Boats

If there is a local tsunami and you are moored in a harbour, abandon your boat immediately. Head for high ground.

Floatplanes

If you are in a floatplane in a harbour, take off as soon as possible. Land safely on a lake or another area not at risk.

More information is available for boaters.

After a Tsunami

If a Tsunami Warning, Advisory or Watch has been issued for your area, monitor local media and follow the instructions of local emergency officials.

Local government officials will tell you when the danger has passed by cancelling the Tsunami Alert.

Additional Resources

Learn more about tsunami hazards in the Capital Region by visiting the Coastal Flood Inundation Mapping Project that includes new tsunami modelling completed in 2020. 

Visit PreparedBC to download the Earthquake and Tsunami Guide.

Visit the National Tsunami Warning Center (NTWC) which provides tsunami warnings to California, Oregon, Washington, British Columbia and Alaska.