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THE TRUTH ABOUT TSUNAMIS: Devastating Forces of Nature or Our Friends?

THE TRUTH ABOUT TSUNAMIS: Devastating Forces of Nature or Our Friends?. Ben Black EPS 131 Professor Tziperman. What is a tsunami?. A tsunami series of waves generated by a displacement of water. Tsunamis can be extremely destructive when they contact a shoreline. How is a tsunami generated?.

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THE TRUTH ABOUT TSUNAMIS: Devastating Forces of Nature or Our Friends?

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  1. THE TRUTH ABOUT TSUNAMIS:Devastating Forces of Nature orOur Friends? Ben Black EPS 131 Professor Tziperman

  2. What is a tsunami? • A tsunami series of waves generated by a displacement of water. Tsunamis can be extremely destructive when they contact a shoreline.

  3. How is a tsunami generated? • Mudslides • Earthquakes • Vulcanism • Meteor Impacts

  4. Tsunami Waves in Deep Water • Extremely long wavelength (often 100 miles) • Means less energy loss • Speed proportional to depth (600 mph in deep ocean): C = (gh)^.5 • (NOTE! Still shallow water waves) • In deep ocean, amplitude of only several feet • Period of 60 or so minutes

  5. But When Tsunamis get to Shallow Water… • Energy in the wave not immediately diminished • Shorter wavelength • Slower • So higher! Up to 100 feet high

  6. The Impact of Tsunamis • A series of waves • Erosion • Flooding • Deadly—thousands killed in past century • Can impact entire Pacific Inundation of Aonae During Hokkaido-Nansei-Oki Tsunami, 1993. Modeling by Vasily Titov.

  7. Recent Tsunamis • 1960—9.5 Earthquake in Chile (largest of the century). 122 killed in Japan, 16,000 miles away! • 1964—9.3 Earthquake in Alaska. 20 foot waves in Crescent City, CA. • 1992—7.6 Earthquake in Nicaragua. 170 dead, 13,000 homeless. • 1 global tsunami per 12 yrs

  8. Tsunami Prediction • Very difficult to actually detect waves—low amplitude, long wavelength • Based on Earthquakes, tidal stations • >6.75 Richter EarthquakeTsunami Watch Bulletin • Potential tsunami readings from tidal stations  Tsunami Warning Bulletin • Unreliable: 75% of warnings since 1948 false • Agencies: Pacific Tsunami Warning Center, National Agencies, National Weather Service

  9. Research Paper • Giant landslides, mega-tsunamis, and paleo-sea level in the Hawaiian Islands • G. M. McMurtry, P. Watts, G. J. Fryer, J. R. Smith and F. Imamura • Marine Geology Volume 203, Issues 3-4, 30 January 2004, Pages 219-233.

  10. Authors explore effects of giant submarine landslides over past 5 Ma in Hawai’i. Model volcano flank collapse: 6 km^3 Almost 1000 m wave Giant Landslides Lead to Giant Tsunamis

  11. GSLs correlate with onset of interglacial periods More water retained by volcanoes Currently seeing similar effects on Kilauea Correlation of GSLs with Climate

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