What Is a Tsunami

Tsunamis (pronounced soo-ná-mees), also known as seismic sea waves (mistakenly called “tidal waves”). They are a series of waves (not just one big one), most often generated by a major earthquake beneath the ocean floor. The time between crests can range from minutes to hours, and in height from a few centimetres to several metres. In the deep ocean, the waves travel about 800 kilometres per hour, but, start to slow in shallower, coastal waters where their heights increase dramatically.

Tsunami Preparedness

If you live in coastal British Columbia, know your Tsunami Notification Zone, then get prepared to manage on your own for a minimum of 72 hours.

How to Prepare

  • Review Before an Emergency for general information on how to prepare.
  • Prepare your family plan and your property.
  • Have a plan and practice it with your family.
  • Review our Tsunami Safety Checklist (PDF) .
  • Learn the tsunami alert terminology.
  • If you live in coastal British Columbia, know your Tsunami Notification Zone (PDF).
  • Learn more by reading the Earthquake and Tsunami Awareness Manual (PDF).
  • Know the height of your street above sea level and the distance of your street from the coast or other high-risk waters. Evacuation orders may be based on these numbers.
  • If you are a tourist, familiarize yourself with local tsunami evacuation protocols. You may be able to safely evacuate to the third floor and higher in reinforced concrete hotel structures.
  • If an earthquake occurs and you are in a coastal area, turn on your radio to learn if there is a tsunami warning.
Download: Earthquake and Tsunami Preparedness Guide
Download: Tsunami Safety Checklist

During a Tsunami

  • Earthquakes are often a precursor to a tsunami. If you feel strong shaking, drop, cover and hold on. Then move to higher ground or, in some communities, a pre-identified safe area.
  • Tsunami waves can last several hours, so stay there until you receive the “All Clear” message from your local government before assuming the event is over. Never go to the beach to watch the waves. A tsunami can move faster than you can run.
  • Follow the evacuation order issued by authorities and evacuate immediately. Take your animals with you.
  • Move inland to higher ground immediately. Pick areas 100 feet (30 meters) above sea level or go as far as 2 miles (3 kilometers) inland, away from the coastline. If you cannot get this high or far, go as high or far as you can. Every foot inland or upward may make a difference.
  • Stay away from the beach. Never go down to the beach to watch a tsunami come in. If you can see the wave you are too close to escape it. CAUTION - If there is noticeable recession in water away from the shoreline this is nature's tsunami warning and it should be heeded. You should move away immediately.
  • Save yourself - not your possessions.
  • Remember to help your neighbors who may require special assistance - infants, elderly people, and individuals with access or functional needs.

After a Tsunami

  • Return home only after local officials tell you it is safe. A tsunami is a series of waves that may continue for hours. Do not assume that after one wave the danger is over. The next wave may be larger than the first one.
  • Go to a designated public shelter if you have been told to evacuate or you feel it is unsafe to remain in your home.
  • Avoid disaster areas. Your presence might interfere with emergency response operations and put you at further risk from the residual effects of floods.
  • Stay away from debris in the water; it may pose a safety hazard to people or pets.
  • Check yourself for injuries and get first aid as needed before helping injured or trapped persons.
  • If someone needs to be rescued, call professionals with the right equipment to help. Many people have been killed or injured trying to rescue others.
  • Help people who require special assistance—infants, elderly people, those without transportation, people with access and functional needs and large families who may need additional help in an emergency situation.
  • Continue listening to your local radio or television station for the latest updates.
  • Stay out of any building that has water around it. Tsunami water can cause floors to crack or walls to collapse.
  • Use caution when re-entering buildings or homes. Tsunami-driven floodwater may have damaged buildings where you least expect it. Carefully watch every step you take.
  • To avoid injury, wear protective clothing and be cautious when cleaning up.

How Will I Know If a Tsunami is Coming?

B.C. receives notification of a potential distant tsunami from the U.S. National Tsunami Warning Center. All information is then assessed by federal and provincial emergency officials and technical staff to determine if there is a threat to coastal BC.

If a tsunami threat is identified, Emergency Management BC will activate the Provincial Emergency Notification System (PENS), which notifies local communities and agencies with information on alert levels for the province’s five tsunami zones. Each zone includes all islands and inlets within it. What zone are you in? Emergency response plans are implemented at the local level as required.

You can also subscribe to Twitter, text and email notifications via the Intergovernmental Oceanographic Commission, US National Tsunami Warning Center (@NWS_NTWC) and Emergency Info BC (@EmergencyInfoBC).

Throughout the event, official tsunami emergency warnings and information will be broadcast by radio, television, telephone, text message, door-to-door contact, social media, weather radios and/or outdoor sirens. Always follow instructions from local emergency officials.

Types of Tsunami Alerts

There are five alert levels and each of which has a distinct meaning.  The alert levels are: 
  • Warning: Flood Wave Possible | Full evacuation suggested.
  • Advisory: Strong Currents Likely | Stay away from the shore.
  • Watch: Danger Level Not Yet Known | Stay alert for more information.
  • Information Statement: Minor Waves At Most | No action suggested.
  • Cancellation: Tidal Gauges Show No Wave Activity | Confirm safety of local areas