Natural Hazards and Disasters
Tsunamis and tropical cyclones
Explain why tsunamis and cyclones devastate coasts.
Tsunamis: sea-floor movement in earthquakes or eruptions displaces water.
In deep water they are fast (about 700 km/h) with long wavelength and small height; near the coast they slow and grow up to 15 m. [The book wrongly says they are faster in shallow water.]
Cyclones: 30° N-30° S, 500-1,000 km across; need warm moist air, Coriolis force, instability, little wind shear.
Bay of Bengal cyclones peak in October-November; winds average 180 km/h; storm surges flood coasts.
Mitigation: warning systems, cyclone shelters, embankments, coastal forests.
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