Earthquake hazards and risk on Canada's west coast
Geologists and geophysicists working along west coast of North America from northern California to southwest British Columbia have demonstrated that giant (magnitude-9) earthquakes occur along the Cascadia subduction zone, where the oceanic Juan de Fuca plate moves down beneath the edge of North America. The evidence includes coseismic land-level change, tsunami deposits, liquefaction structures, and turbidites on the Pacific Ocean floor. The turbidite record spans the past 10,000 years and provides evidence for 20 giant earthquakes with an average return period of 500 years. The most recent of these earthquakes happened in January 1700. Satellite GPS data extending back to the mid-1990s shows a pattern of surface deformation consistent with locking of the megathrust fault separating the Juan de Fuca and North America plates in the build-up to the next giant earthquake. Although the next of these earthquakes will damage all cities along the length of the subduction zone, the risk profile of far more frequent, magnitude 6 and 7 crustal earthquakes is greater than that of much larger plate-boundary events.
https://www.munich-geocenter.org/events/seminars/frontiers-in-earth-sciences-18/earthquake-hazards-and-risk-on-canadas-west-coast
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Earthquake hazards and risk on Canada's west coast
Speaker
John Clague
(
Simon Fraser University, British Columbia)
Abstract
Geologists and geophysicists working along west coast of North America from northern California to southwest British Columbia have demonstrated that giant (magnitude-9) earthquakes occur along the Cascadia subduction zone, where the oceanic Juan de Fuca plate moves down beneath the edge of North America. The evidence includes coseismic land-level change, tsunami deposits, liquefaction structures, and turbidites on the Pacific Ocean floor. The turbidite record spans the past 10,000 years and provides evidence for 20 giant earthquakes with an average return period of 500 years. The most recent of these earthquakes happened in January 1700. Satellite GPS data extending back to the mid-1990s shows a pattern of surface deformation consistent with locking of the megathrust fault separating the Juan de Fuca and North America plates in the build-up to the next giant earthquake. Although the next of these earthquakes will damage all cities along the length of the subduction zone, the risk profile of far more frequent, magnitude 6 and 7 crustal earthquakes is greater than that of much larger plate-boundary events.
