Tsunami

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A tsunami is a natural hazard where a series of long, surge-like waves are generated when a large amount of ocean water is rapidly displaced. Most tsunamis are caused by major earthquakes, where there is significant displacement of the ocean floor. Tsunami waves differ from ordinary coastal waves in that the entire column of water from the ocean floor to the surface is affected. These waves contain considerable energy and can travel further inland compared to ordinary waves. A tsunami may not look like a wave at all but will have very strong currents under its surface.

Tsunamis are a challenging hazard to respond to. The arrival time of the wave generated far out at sea can be predicted accurately, but the intensity of the wave when it reaches shore is more difficult to predict. To help prepare for a potential tsunami, the Strathcona Regional District (SRD) has completed a risk assessment for the Northwest Vancouver Island.

Local vs. Distant Tsunamis

On the west coast of North America, tsunamis are categorized as local or distant, depending on the location of the earthquake and the size of the area affected. 

Local Tsunamis 

A local tsunami is a tsunami that begins at a source within 1,000 km, or less than 1 hour tsunami travel time, from the area impacted. For the west coast of the SRD, it could be minutes before the tsunami reaches the shoreline.  

Damage and inundation from a local tsunami is typically widespread. Major earthquakes are often a precursor to a local tsunami. The most dangerous tsunami threat to the BC coast will follow a major, “megathrust” earthquake. Such an earthquake will cause ground shaking lasting three to five minutes. The shaking will be so strong it will be difficult to stand in many places. 

Distant Tsunamis

A distant tsunami is a tsunami that begins at a source more than 1,000 km away, or more than 3 hours travel time, from the area impacted. Damage from a distant tsunami is typically limited to low-lying coastal areas. Response to a distant tsunami is significantly different than to a local tsunami. Typically, there is more time for an official warning and evacuation to safety. More evacuation infrastructure and support will be readily available during this type of event.

Northwest Vancouver Island (NWVI) Risk Assessment and Mapping

The northwest coast of Vancouver Island is characterized by its natural beauty and rich history. Open to the Pacific Ocean, this region is particularly exposed to tsunami hazards.

In partnership with local First Nations, the SRD has completed a tsunami risk assessment to strengthen public awareness and support emergency planning and management.

NWVI Tsunami Risk Project 

Westcoast Tsunami Story Map

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