According to Earthquakes Canada, a tsunami is a series of huge ocean waves caused by a rapid, large-scale disturbance of the sea water. Tsunamis can be caused by submarine volcanic eruptions, submarine landslides, meteor impact, and major earthquakes occurring beneath the seabed causing large vertical movements. In deep water, tsunami waves are less than a metre high, but they can travel at speeds exceeding 800 kilometres per hour and can easily cross an entire ocean basin. When they reach shallow water or narrow inlets the waves slow down and the height can build into a wall of water, which can cause major damage on the shore. The City of Victoria said the community is not at risk compared to places like Tofino and Ucluelet, which are on the open water. Those communities have notification sirens. Victoria does also not expect a large, fast tsunami, such as the one in Japan in 2011. According to the city, the main tsunami threat to Victoria is from a Cascadia Subduction Zone earthquake off the Pacific Coast of Vancouver Island. Tsunami modelling has been completed for the region for the most likely and highest impact scenario, which is a 9.0 magnitude Cascadia Subduction Zone earthquake. An earthquake that happens far away that is not felt may cause a very low-risk and low-impact tsunami event in Victoria. The city said the shaking from an earthquake is a warning of a local tsunami. Anyone who is near the ocean and feels an earthquake that makes it difficult to stand for 60 seconds or more should drop, cover, hold on, count to 60 once all shaking has stopped and move to higher ground or inland immediately. This could happen before an official tsunami warning and people are advised not to wait for the official warning. The projected arrival for a local tsunami at Victoria’s harbour is 76 minutes with a maximum water level of 2.5 metres (8.2 feet). This estimate is based on a 9.0 Cascadia Subduction Zone earthquake. The City of Victoria receives notifications of potential distant tsunamis from the National Tsunami Warning Centre (NTWC). Vic-Alert, the city’s subscriber-based emergency notification service and the government’s Alert Ready system, both send out distant tsunami warnings. The city said residents located four metres (13 feet) above sea level is safe from a tsunami. A compass app on a phone or Google Earth can show the approximate elevation of an address.
#TsunamiPreparednessWeek starts SUN! Altho tsunamis are rare, you're safe in Capital Region 4m or 13ft above sea level. Use your mobile device's compass to see approx elevation or Google Earth. Check out Vic Tsunami Hazard Map & learn to be #TsunamiReady https://t.co/RQzGBeZuFw pic.twitter.com/t7ECeaolbB— City of Victoria (@CityOfVictoria) April 5, 2019
The tsunami hazard zones can be seen on this map. During a tsunami warning, the city said people must move to higher ground immediately, on foot or bicycle if possible, if they are in a low coastal area, beach, marina or harbour. Higher ground may only be a few blocks away. People should take an emergency kit with them and not stop to watch the waves. People will not be able to return to lower ground until officials say it is safe to do so. People who are not in tsunami hazard zone should stay in place, assist family, friends and neighbours in need of shelter and stay tuned to local media.