This causes tremendous strain and deformation of the Earth's crust in the coastal region and causes ongoing earthquake activity. In the interval between great earthquakes, the tectonic plates become stuck together, yet continue to move towards each other. However, because the fault is offshore, it is not the greatest earthquake hazard faced by major west coast cities. We now know that a similar offshore event will happen sometime in the future and that it represents a considerable hazard to those who live in southwest B.C. Geological evidence indicates that 13 great earthquakes have occurred in the last 6000 years. The recognition of definitive signatures in the geological record tells us the Januevent was not a unique event, but has repeated many times at irregular intervals of hundreds of years. The earthquake also left unmistakeable signatures in the geological record as the outer coastal regions subsided and drowned coastal marshlands and forests that were subsequently covered with younger sediments. It is the accurate descriptions of the tsunami and the accurate time keeping by the Japanese that allows us to confidently know the size and exact time of this great earthquake. The tsunami swept across the Pacific also causing destruction along the Pacific coast of Japan. These events are recorded in the oral traditions of the First Nations people on Vancouver Island.
On the west coast of Vancouver Island, the tsunami completely destroyed the winter village of the Pachena Bay people with no survivors. The shaking was so violent that people could not stand and so prolonged that it made them sick. The earthquake shaking collapsed houses of the Cowichan people on Vancouver Island and caused numerous landslides. The Cascadia fault is the boundary between two of the Earth's tectonic plates: the smaller offshore Juan de Fuca plate that is sliding under the much larger North American plate. The undersea Cascadia thrust fault ruptured along a 1000 km length, from mid Vancouver Island to northern California in a great earthquake, producing tremendous shaking and a huge tsunami that swept across the Pacific. The M9 Cascadia Megathrust Earthquake of January 26, 1700Īt 9PM on Januone of the world's largest earthquakes occurred along the west coast of North America.
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