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 ID: 1025081
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1. Estimating Ocean Depth by TsunamiGoals Student analysis of real data (reproduces 19th 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 TsunamiContext 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 EquationsCelerity of a deep-water wave is C = L/T = 1.25L0.5 = 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 TsunamiExtrashttp://williams.best.vwh.net/gccalc.htm
5. Tsunami Travel Distances LocationDistance (km)Epicenter61° 6' N 147° 30' W0Whidbey Bay, AK 59° 58' 148° 57' W149Kodiak AK 57° 50' N 152° 30' W461Tofino BC 49° 09' N 125° 54' W1898Crescent City CA 41° 46' N 124° 13' W2661Hilo, HI 19° 44' N 155° 4' W4632Kushiro, Japan43° 00' N 144° 22' E5236Kwajalein, Marshall I.8̊ 45’ N 167̊ 45' E6867La Punta, Peru12° 05' S 77° 10' W10544Sydney, Australia33° 51' S 151° 14' E11887Accounts for “corners”
6. Estimating Ocean Depth by Tsunami
7. SolutionDistance (km)Calc Celerity (m/sec)Calc Water depth (m)Epicenter 0----Whidbey Bay AK149130.71742Kodiak AK461160.12615Tofino BC1898155.12454Crescent City CA2661182.53399Hilo, HI4632238.35793Honolulu, HI4493236.25694Kushiro with corner5236210.34512Kwajalein, Marshall Islands6867227.15262La Punta with corner10544188.03605Sydney, Australia11887192.53783
8. Analysis of ValuesHere is what I seeEpicenter to Alaska shallow seafloor/continental shelf British Columbia wave 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, Sydney Intermediate 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 TsunamiExtrasI 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)