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How Exactly Does A Tsunami Start?

LOS ANGELES (CBS) — Once an earthquake hits, a series of events are set in motion to form an tsunami.

Any earthquake can create a tsunami.

The dictionary defines a tsunami as "an unusually large sea wave produced by a seaquake or undersea volcanic eruption." The origin, Japanese. Tsu for "harbor" and nami for "wave."

Melissa McCarty, reporting for KCAL 9 News at 10 p.m. Friday, talked to scientists at Caltech in Pasadena to find out about the anatomy of a tsunami...beyond the definition.

She finds the quake must hit a certain magnitude under the ocean. Also, the sea floor has to move in a significant way. The two plates collide with each other forcing water to run down, as if going down a hill.

That movement forms the tsunami...and it moves with the speed of a jet plane.

Friday's 8.9 quake in Japan was significantly strong enough to speed up the Earth's rotation by 1.6 micro seconds. The Earth's sea floor moved 60 feet. Japan moved 12 feet. And it sunk by two.

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