Current Tectonic Theory
Plate Tectonic Theory holds that the Earth's crust is composed of a number of "plates" that are moved about by rising and descending plumes or currents of molten rock deep within the earth. Crustal material is created at "Zones of Divergence" and is reabsorbed at "Zones of Convergence". Plates also slip past one another, as along the San Andres Fault.
Plate boundaries are sites of much seismic activity and British Columbia is no exception. Most of the province's earthquakes, however, occur off the west coast.
British Columbia is most directly affected by the actions of the North American Plate and the Juan de Fuca and Explorer Plates. In the 1970s, the Juan de Fuca Plate was moving 4 - 6 centimetres annually.
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