Earthquake epicenters from a catalogue of the earthquakes in Canada, the Northern United States, Alaska, and the Aleutian Islands are plotted on maps. This catalogue contains the instrumentally located earthquakes within the years 1900 to 1960, and the historical record of earthquakes that have been felt along die St. Lawrence River from 1534, Accumulated values of strain release are computed for each unit area (1° × 1°) on the earth's surface. Contour maps are drawn from these. The areas of greatest activity are along the Aleutian arc, in Alaska, along Canada's west coast, and in the St. Lawrence Valley. It isshown that within a 100-year period there may be an earthquake near magnitude 71/4 below Quebec City, and near Vancouver Island. Areas of lesser activity are shown.

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