earthquakes 6

earthquakes 6 - A.D accompanied by a tsunami in Puget...

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Earthquakes 6 notes Tectonics and earthquakes of western US. The mountains of western North America are called the cordillera and they are the still  evolving product of 780 million years of construction. Their appearance today is largely the  result of earth movements during only the past 20-30 million years. The movements continue  today and are responsible for earthquakes throughout the cordillera.  Queen charlotte ocean fault is similar to san andreas fault, stretching into Alaska.  Major western cities at seismic risk -LA : thrust, strike slip faulting - SD: strike slip -SF : strike slip - portland: subduction zone -Reno: normal -Salt lake – normal faulting -Seattle: subduction eq’s thrust faulting -Vancouver subduction zone The Seattle fault zone - north south shortening.  -forms 4-6 km wide, west trending zone of three or more reverse faults - 7m of uplift occurred during a large M> 7 earthquake on the seattle fault about 900 - - - 
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Unformatted text preview: A.D accompanied by a tsunami in Puget sound- Rates of displacement and earthquake recurrence intervals for the Seattle fault are essentially unknown. Cascadia subduction zone northwestern NA, boundary between juan de fuca and north American plate-its trenches disappeared only because rivers filled it up after the glaciers left. - the two plates are locked, the NA plate is being uplifted and shortened. - such large earthquakes occur every 539 years. Basin and range province of the western US is a world-famous region of crustal extension and thinning. Extension occurs by displacements along the normal faults that bound the many mountain ranges within the province and that define its western sierra Nevada and eastern Wasatch front boundaries....
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