EARTHSS 17 Lecture 11: EARTHSS Lecture 11
2 Nov 2016
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Sumatra tsunami: sunday dec. 26, 2004 m9. 1 earthquake, broke 1200 km fault length pushed the plate up several meters in a split second, 250,000 killed, no warning network, thailand. Sometimes called tidal waves but not related to tides: generated by any sudden displacement of large volume of water. Volcanic eruptions, landslides or rockfalls, volcano flank collapses, asteroid impacts, and earthquakes cause this displacement of water: transform boundaries cannot cause tsunamis. There is no up or down movement. There is only back and forth so there is no displacement. Ho(cid:449)e(cid:448)er high the plate goes, that"s ho(cid:449) high the (cid:449)ater (cid:449)ill (cid:373)o(cid:448)e. Anatomy of a wave: l=wavelength, t=wave period, h=wave height. Wave frequency the number of wave crests passing point a each second. Wave period the time required for the wave crest at point a to reach point b: typical tsunamis have. Orbitals: circular motion felt by particles due to the advancement of the wave.
