Geological evidence also indicates that huge subduction earthquakes have struck this coast every 300-800 years. The main map presents the geographic distribution of average annual loss (USD) normalised. Current crustal deformation measurements in this area provide evidence for this model. The Global Seismic Risk Map (v2018.1) comprises four global maps. At some time in the future, these plates will snap loose, generating a huge offshore “subduction” earthquake – one similar to the 1964 M=9.2 Alaska earthquake, or the 1960 M=9.5 Chile earthquake. It is this squeezing of the crust that causes the 300 or so small earthquakes that are located in southwestern British Columbia each year, and the less-frequent (once per decade, on average, damaging crustal earthquakes (e.g., a magnitude 7.3 earthquake on central Vancouver Island in 1946). There is good evidence that the Juan de Fuca and North America plates are currently locked together, causing strain to build up in the earth’s crust. The ocean plate is not always moving though. Here, the much smaller Juan de Fuca plate is sliding (subducting) beneath the continent (it is about 45 km beneath Victoria, and about 70 km beneath Vancouver). This region is called the Cascadia subduction zone. West of Vancouver Island, and extending from the north tip of the Island to northern California, the oceanic Juan de Fuca plate is moving towards North America at about 2-5 cm/year. This earthquake, larger than the 1906 San Francisco earthquake, caused nearly a 500-km-long segment of the Queen Charlotte fault to break. Canada’s largest historical earthquake – a magnitude 8.1, occurred along this fault on August 22, 1949.
The boundary between these two giant plates is the Queen Charlotte fault – Canada’s equivalent of the San Andreas fault.
#Earth quake map windows
In Prince Rupert, windows were shattered and buildings swayed.įrom northern Vancouver Island, to the Queen Charlotte Islands, the oceanic Pacific plate is sliding to the northwest at about 6 cm/year relative to North America. In Terrace, on the adjacent mainland, cars were bounced around, and standing on the street was described as “like being on the heaving deck of a ship at sea”. Chimneys toppled, and an oil tank at Cumshewa Inlet collapsed. The shaking was so severe on the Haida Gwaii that cows were knocked off their feet, and a geologist with the Geological Survey of Canada working on the north end of Graham Island could not stand up.
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