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Explore the catastrophic impacts of tsunamis―"large harbor waves" with origins like earthquakes, underwater landslides, volcanic collapses, and asteroid impacts. Learn about the Indonesian Tsunami, subduction zones, warning systems, and the importance of tsunami runup and hazard maps in preventing disasters.
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Lecture 6: Tsunamis Our Hazardous EnvironmentGEOG 1110Dr. Thieme
Japanese for "large harbor wave" catastrophic impacts occur thousands of kilometers from geologic source Four possible causes earthquake (along subduction zone) underwater landslide collapse of a volcano asteroid impact Tsunami
Indonesian Tsunami • Indian and Australian plates • eastward subduction beneath Eurasian plate • "stick-slip" of subducting plates • M 9.1 Earthquake on December 26, 2004
Banda Aceh • provincial capital on northern Sumatra • shaking by earthquake • pummeling waves • flooding after land subsided
Distant vs. Local • water depth varies as wave departs epicenter • wave splits into • "local" tsunami along adjacent coast • "distant" tsunami in deep water
Local Tsunami • 1993 in Sea of Japan • 15-30 m waves struck Okushiri Island • arrived only 2-5 minutes after earthquake • 120 people killed
Tsunami Warning System • "buoys in the ocean" • depth gauges • water pressure recorder on sea bottom • also need PUBLIC EDUCATION ! !
Tsunami Hazard Map • indicates possible areas of wave impact • based upon elevation • slope of sea bottom • orientation of coast