Are we at Risk?

The likely threat of a Tsunami will come from a major earthquake in the Cascadia Subduction Zone.   The Cascadia Subduction Zone (CSZ) "megathrust" fault is a 1,000 Km long dipping fault that stretches under the Pacific Ocean, along the west coast of North America from Northern Vancouver Island to Cape Mendocino California.  Tsunamis created elsewhere in the Pacific Ocean are not likely to affect Oak Bay beyond high water, similar to what we experience from a severe winter storm. 

In 2013, local governments in the Capital Regional District (CRD), including Oak Bay, commissioned a tsunami risk assessment which identified Tsunami inundation zones throughout the Region.  In that assessment Oak Bay’s risk was determined to be very low. Click here for the Tsunami Inundation Map.

Even though our risk from a damaging Tsunami is low in Oak Bay, it is important to stay informed and aware of the risk in all the areas in which we live, work or visit.  

Ground Shaking and Changing Sea Levels

The most dangerous tsunami threat to the CRD is from a major earthquake which occurs in the ocean. A tsunami may be generated if the earthquake is strong enough to make it difficult to stand and the shaking lasts longer than 60 seconds.  Another natural warning sign that a tsunami is imminent is the steady rise and fall of sea levels.  The water level may drop so much that the floor of the sea is exposed. 

If you experience or observe any of these natural signals and are in or near an inundation zone, warn others of the risk and seek higher ground immediately. 

It is important to remember that a tsunami is a series of waves and that the first wave is not necessarily the largest wave.  The length of time between waves can be as short as a few minutes or as long as hours.   

Always Be Prepared

  • Make sure your neighbors know of the tsunami potential after a major earthquake.
  • Identify tsunami safe zones within your community.   
  • Be prepared to help others requiring extra assistance reach safety
  • If you are near a tsunami high-risk area (inundation zone), first DROP, COVER and HOLD ON, and then evacuate to higher ground.  Higher ground is defined as 4 meters above the high tide level.  If there isn’t high ground, go as far inland as you can. 
  • Take your Grab & Go kit with you.  Make sure it contains a battery operated radio, so you can stay informed about current conditions and receive updates. 
  • Once you are in a safe place, STAY THERE until a local officials tell you the danger has passed.
  • Never go down to the water to watch or take pictures of the tsunami.  

Tsunami Notifications

A Tsunami Watch (least serious level of alert) is issued if the danger level is not known and you should stay alert.

A Tsunami Advisory (second highest level of alert) indicates that strong currents are likely and you should stay away from the shore. 

A Tsunami Warning (most serious level of alert) indicates that an inundating wave is possible and evacuation may be suggested.  

A Tsunami Cancelation or All Clear – Local government officials will tell you when the danger has passed.

Boost Your Tsunami IQ By

Start by reviewing the PreparedBC TsunamiSmart webpage, which provides an overview of tsunami risk, preparedness and response in British Columbia.

You can also follow @PreparedBC on Twitter for more tips and info, as well as news on what other jurisdictions are doing.

Also check out the helpful links below.

Earthquake & TsunamiSmart Manual
Video: BC’s Tsunami Notification Process 


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