1. Estimating Ocean Depth by Tsunami Goals Student analysis of real data (reproduces 19 th century approach). Reinforce shallow water wave celerity and water depth Student reasoning of how to do this; analysis of tsunami routes Exercise in basic math skills (re-arranging an equation, calculating travel time and velocity, and ocean depth)

2. Estimating Ocean Depth by Tsunami Context Just after introduction to waves: Lecture and lab on waves, wave types, including calculating and graphing shallow and deep water waves, internal waves, and seiches.

3. Possibly Handy Equations Celerity of a deep-water wave is C = L/T = 1.25L 0.5 = 1.56T Celerity of a shallow-water wave is C = (gD) 0.5 L = wavelength (meters)T = wave period (seconds) D= water depth (meters) g=acceleration due to gravity (9.8 m sec -2 )

4. Estimating Ocean Depth by Tsunami Extras http://williams.best.vwh.net/gccalc.htm

5. Tsunami Travel Distances LocationDistance (km) Epicenter 61° 6' N 147° 30' W 0 Whidbey Bay, AK 59° 58' 148° 57' W 149 Kodiak AK 57° 50' N 152° 30' W 461 Tofino BC 49° 09' N 125° 54' W 1898 Crescent City CA 41° 46' N 124° 13' W 2661 Hilo, HI 19° 44' N 155° 4' W 4632 Kushiro, Japan 43° 00' N 144° 22' E 5236 Kwajalein, Marshall I. 8̊ 45’ N 167̊ 45' E 6867 La Punta, Peru 12° 05' S 77° 10' W 10544 Sydney, Australia 33° 51' S 151° 14' E 11887 Accounts for “corners”

6. Estimating Ocean Depth by Tsunami

7. Solution Distance (km) Calc Celerity (m/sec) Calc Water depth (m) Epicenter 0 -- Whidbey Bay AK 149130.7 1742 Kodiak AK 461160.1 2615 Tofino BC 1898155.1 2454 Crescent City CA 2661182.5 3399 Hilo, HI 4632238.3 5793 Honolulu, HI 4493236.2 5694 Kushiro with corner 5236210.3 4512 Kwajalein, Marshall Islands 6867227.1 5262 La Punta with corner 10544188.0 3605 Sydney, Australia 11887192.5 3783

8. Analysis of Values Here is what I see Epicenter to Alaskashallow seafloor/continental shelf British Columbiawave apparently travels close to North America in relatively shallow water Mid-Pacific deepest water depths over very open (Hilo, Kwajalein) ocean (i.e., into center of Pacific) Japan, California, Peru, SydneyIntermediate depths (3300-3800 m) Travel through water depths like those of mid-Pacific but has shallower water on ends to slow wave Average depth ~3600 m

9. Estimating Ocean Depth by Tsunami Extras I once had a Japanese student ask me to explain what connection tsunamis, as defined, had with waves in harbors, which is apparently its primitive meaning. Kinsman (1965)