Earthquakes happen every day across the Pacific Ocean and West Coast of BC and the USA. Major earthquakes are infrequent but invariably will occur. An earthquake is a sudden, violent shaking of the Earth’s crust, producing strong shaking that may last more than a minute or might make it difficult to stand. Areas with homes built on loose and sandy soil near the water may be at higher risk of liquefaction. Liquefaction occurs where the earth shakes so violently that loose soil near the ocean becomes saturated with water which could cause structures to collapse.
A tsunami consists of a series of waves that may last for up to twelve hours. A tsunami may not look like a big wave, but more like a rapid rise and fall in the ocean level. The first wave from a Cascadia Subduction Zone earthquake could arrive in the Tofino area in 20 minutes, and Greater Victoria in 75 minutes, but the largest wave may not arrive until later.
The eastern side of Cowichan region is at a lower risk during a tsunami event but low laying areas may still experience some impacts in the event of a major tsunami. The coastal areas on the western side of the Cowichan region including sections of the West Coast Trail could be in the tsunami inundation zone.
The National Tsunami Warning Centre identifies tsunami threats using deep water buoys, seismometers, and tide gauges. Any seismic activity large enough will trigger a warning that will be broadcast across Cowichan Alert, local media, and other emergency notification systems.