1946 Vancouver Island earthquake
The 1946 Vancouver Island earthquake struck Vancouver Island on the coast of British Columbia, Canada, on June 23 at 10:15 a.m. with a magnitude estimated at 7.0 and 7.5 . The main shock epicenter occurred in the Forbidden Plateau area northwest of Courtenay. While most of the large earthquakes in the Vancouver area occur at tectonic plate boundaries, the 1946 Vancouver Island earthquake was a crustal event. Shaking was felt from Portland, Oregon, to Prince Rupert, British Columbia. This is one of the most damaging earthquakes in the history of British Columbia, but damage was restricted because there were no heavily populated areas near the epicentre, where severe shaking occurred. This earthquake is Canada's largest historic onshore earthquake. However, the greatest earthquake in Canadian history recorded by seismometers was the 1949 Queen Charlotte earthquake, an interplate earthquake that occurred on the ocean bottom just off the rugged coast of Graham Island, which reached magnitude 8.1 on the moment magnitude scale. Background and tectonics The tectonics that caused the 1946 Vancouver Island earthquake are poorly known. No surface expression of the offset was noticed, most likely because the epicenter area is very remote and densely forested. A comprehensive examination and computer interpretation of seismic data from over 50 stations have shown that a possible explanation of the earthquake includes a strike-slip fault corresponding to the lengthy axis of Vancouver Island, known as the Beaufort Range Fault. A fault running across Vancouver Island, corresponding to the projection of the underwater Nootka Fault on the British Columbia Coast, is also a possibility but an unlikely one because the earthquake showed no evidence of offsets along with a series of highways that follows much of the eastern coastline of Vancouver Island, called Island Highway, and other roads between Courtenay and Campbell River. The estimated depth of the earthquake places it within the continental crust, not at the margin with the Cascadia subduction zone, and certainly not inside the subduction zone itself. Specifically, the earthquake's epicenter was positioned somewhere in the Forbidden Plateau region, in central Vancouver Island. Damage and casualties Though very destructive, the earthquake caused only two deaths: Jacob L. Kingston, aged 69, and Daniel Fidler, who was 50. Kingston suffered a heart attack in Seattle, while Fidler drowned when his dinghy was swamped by a wave. In Vancouver, damage consisted of lofty buildings oscillating violently, and a piece of masonry fell from the local railway station. In addition, within the city, at least one gas line cracked and several power outages occurred. Fires broke out in several chimneys, and at least one swing-span bridge was fractured by the shaking. In the Hotel Vancouver, which housed the elderly and caught on fire, more than 500 war veterans' families fled the flames. One writer, George Finley, stated that the Lions' Gate Bridge "swayed like a leaf", coinciding with a "low, rumbling sound, like a deep growl." The 1946 Vancouver Island earthquake demolished 75% of the chimneys in the communities of Cumberland, Union Bay, and