1. THE TRUTH ABOUT TSUNAMIS: Devastating Forces of Nature or Our 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, 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

10. Giant Landslides Lead to Giant Tsunamis
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

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