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Seismic Activity on the West Coast “Waiting for the Big One” Earthquakes in Western Canada Most earthquake prone region in Canada Part of the Pacific Ring of Fire, the concentration of earthquakes along the west coast is related to the presence of active faults, or breaks in the earth's crust Plates can either slide past one another, or they can collide, or they can diverge Pacific Ring of Fire Earthquakes in Western Canada The west coast of Canada is one of the few areas in the world where all three types of plate movements take place Subduction – Sliding past one another Collision – Crashing into one another Divergence – Moving away from one another Plate Movements on the West Coast Cascadia Subduction Zone Here, the much smaller Juan de Fuca plate is sliding (subducting) beneath the North American plate Juan de Fuca and North America plates are currently locked together, causing strain to build up in the earth's crust. At some time in the future, these plates will snap loose, generating a huge offshore "subduction" earthquake - one similar to the 1964 M=9.2 Alaska earthquake, or the 1960 M=9.5 Chile earthquake Japanese Tsunami Tsunamis A tsunami is a wave train, or series of waves, generated in a body of water by an impulsive disturbance that vertically displaces the water column Subduction earthquakes are particularly effective in generating tsunamis As the tsunami's speed diminishes as it travels into shallower water, its height grows http://www.youtube.com/watch?v=4YPOK_3r8Dc http://www.theguardian.com/world/video/2011/mar/12/japan-confronts-quake-devastationvideo Tsunamis What do we need to do as a class? Take cover under a table or desk, hold on Stay away from doors and windows Count to 60 seconds in unison Wait 10 seconds Count to 60 in unison again Stay calm, evacuate carefully to exit Homework 1. Draw, label and colour the tectonic processes on the Pacific Coast 2. Include in your diagram of tectonic processes: - North America Plate - Juan de Fuca Strait - Juan de Fuca Ridge - Pacific Plate - Direction of plates - Seattle - Vancouver - Victoria - Vancouver Island - Cascade Volcanoes - Megathrust Quakes
