June 23, 1946 Earthquake: British Columbia, Canada

This is Vancouver Island's largest historic earthquake (and Canada's largest historic onshore earthquake). The epicenter was in the Forbidden Plateau area of central Vancouver Island, just to the west of the communities of Courtenay and Campbell River. This earthquake caused considerable damage on Vancouver Island and was felt as far away as Portland, Oregon and Prince Rupert, British Columbia. The earthquake knocked down 75 percent of the chimneys in the closest communities, Cumberland, Union Bay, and Courtenay and did considerable damage at Comox, Port Alberni, and Powell River (on the eastern side of the Strait of Georgia). Some chimneys were shaken down at Victoria and people in Victoria and Vancouver were frightened - many running into the streets.
Two deaths resulted from this earthquake; one person drowned when a small boat was capsized in a wave generated by the collapse into the sea of the end of a sand spit [near Deep Bay, about 30 km SE of Courtenay], and the other person died from a heart attack in Seattle.
Maximum observed Modified Mercalli Intensity (MMI) VIII

Abridged from Significant Canadian earthquakes 1600-2017, by Maurice Lamontagne, Stephen Halchuk, John F. Cassidy and Garry C. Rogers, Geological Survey of Canada Open File 8285, Ottawa, Canada: 2018.

Heavy damage occurred in the epicentral area. The Canadian Hydrographic Department reported the bottom of Deep Bay in the Strait of Georgia sank from about 3 to 25 m. A 3-m vertical ground shift occurred on Read Island [northeast of Campbell River], and ground settlements as much as 30.5 m were observed at other points.
In the United States, some chimneys fell at East Sound, San Juan County, Washington; a concrete mill was damaged at Port Angeles; and buildings were damaged slightly at Northport, Port Townsend, and to the south as far as Olympia. At Seattle, plaster fell in the County-City Building, and a few bricks fell from the Sears-Roebuck Building. The quake was also felt at several towns in Oregon. (Ref. 19, 38, 258.)
Maximum observed Modified Mercalli Intensity (MMI) VIII

Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.

Location and Magnitude updated in catalog 08-Sep-2026
Reference:
Lamontagne, M., Halchuk, S., Cassidy, J.F., and Rogers, G.C. (2018),
Significant Canadian earthquakes 1600-2017,
Geological Survey of Canada Open File 8285, Ottawa, Canada

There was a very strong earthquake in western Canada and in the northwestern United States with source in the central part of the Campbell River and further to Quadra island and Reid Island inclusively. (reference #415)

Reference #45 lists epicenter 49.9N, 125.3W, property damage, magnitude 7.3

One man, Capt. Daniel Fiddler, was drowned off Maple Guard Spit when his dinghy was overturned at the time of the earthquake (reference #2598)