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Earthquakes, Volcanoes, and a Modern Journey to the Center of the Earth Michael Wysession Professor of Geophysics, Dept of Earth and Planetary Sciences Washington University, St. Louis, Missouri PLATE “Plate Tectonics,” The Basic Idea: Locations of the Major Tectonic “Plates” A Global Map of Earthquakes Also Shows the Plate Boundaries Japanese Folklore: Earthquakes caused by giant Namazu. Following the 1755 Lisbon earthquake on All Saint’s Day, the Spanish Inquisition burned people at the stake to atone for the city’s sins. The San Andreas Fault More reasonable assessment, based upon actual seismicity The Global Seismic Hazard Assessment Program (GSHAP), with the support of the International Council of Scientific Unions (ICSU), and endorsed as a demonstration program in the framework of the United Nations International Decade for Natural Disaster Reduction (UN/IDNDR). Earthquakes occur where earthquakes occur, and… Earthquakes occur where seismometers exist Earthquakes occur where earthquakes occur Earthquakes occur where seismometers exist Almost no seismometers!! The NMFZ is associated with the Reelfoot Rift – a failed rift zone that was active 750 million years ago, as the supercontinent Rodinia began to break up. The Reelfoot Rift is a region of lower elevation (which is why the Mississippi River flows down through it!). New Madrid earthquakes Notice all the earthquakes EAST of the NMSZ! The NMSZ might be finished (for now?). It might be time for a different failed rift to undergo some continental creaking. o Historical o Instrumental Wabash Valley Seismic Zone earthquakes: The latest - Mw 5.2 on April 18, 2008 (last Friday!) A DEVASTATING EVENT: THE SUMATRA EARTHQUAKE OF DECEMBER 26, 2004 Burma Microplate Sumatra Indian Plate Northward Motion of India Deforms the Entire Region Sumatra Earthquake Sumatra-Andaman Dec 26, 2004 EQ & Tsunami Banda Aceh: Before…. Banda Aceh: Before…. and After….. So….could this happen in America?!? Massive landslides in places like the Canary Islands could cause enormous Atlantic tsunamis! There have also been Giant Undersea Landslides in the Puerto Rico Trench!!!! For Large Earthquakes, Seismic Waves Circle the Earth for Months to Years, Making it Ring Like a Gong. (Earth’s Lowest Note, With a Period of ~54 Minutes, is an E, Twenty Octaves Below Middle E on a Piano.) Courtesy of J. Tromp Courtesy of IRIS Can Seismologists Predict Earthquakes? (Only one earthquake was ever successfully predicted: 1975 Tangshan, China) Earthquake Prediction: Animal Behavior? Earthquake Forecasting: Seismic Gap Hypothesis? Lack of success reminiscent of New York City “bear gap” hypothesis USGS Forecast: Parkfield Earthquake in 1987 On Sep. 28, 2004, the Parkfield EQ finally happened!! Was it is successful prediction??? Seismic Imaging Has Allowed Us to Explore the Interior of Our Planet…. Courtesy of A. Dziewonski A Medical CT-Scan DOWNWELLING UPWELLING Courtesy of S. Zhong For a copy of this presentation, please email me at: [email protected] The information can also be found (and more) in the 48-lecture Teaching Company video course “How the Earth Works”