Over 4,000 m of open ocean a tsunami stands less than half a metre tall and ships pass over it unaware, even though it is travelling at roughly 710 km/h, as fast as a jet. In shallow water its speed falls as the square root of depth, the wavelength contracts, and all that energy is forced into height. Sometimes the sea first pulls unnaturally far out, minutes before the water comes in — the very sign that saved an entire beach in 2004.
Over 4,000 m of open ocean a tsunami stands less than half a metre tall and ships pass over it unaware, even though it is travelling at roughly 710 km/h, as fast as a jet. In shallow water its speed falls as the square root of depth, the wavelength contracts, and all that energy is forced into height. Sometimes the sea first pulls unnaturally far out, minutes before the water comes in — the very sign that saved an entire beach in 2004.
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