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Unformatted text preview: Chapter 5- More United States and Canadian Earthquakes Earthquake- significant- USGS deems magnitude of 6.5 of higher Western North America: Plate Tectonic-Related Earthquakes North American plate is moving into the Pacific plate at 2.5 cm/yr and that a tremendous volume of the Farallon plate has subducted beneath N. America. April 1949, Puget Sound Washington- Down-to-the-east movements of the subducting Juan de Fuca plate, surface wave magnitude was 7.1 with eight deaths. $150M. April 1965, Tacoma- Seattle area- 6.5 M killing seven people totaling $50M. Because of subducting Juan de Fuca plate is only 10 to 15 million years old and is warm and buoyant enough to couple with the North American plate. Seattle fault zone occurred 1,100 years ago 1) Restoration Point was uplifted about 7 m. 2) Large landslides carried trees in growth position to the bottom of Lake Washington. 3) Tsunamis buried logs and trunks. 4) Major rock avalanches occurred around same time....
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- Spring '08