Q&A: How long before tsunami after earthquake happens?

Question by Laurie L: How long before tsunami after earthquake happens?
An earthquake struck in Japan and a tsunami is expected. What is the length of time between the earthquake and the tsunami?

Best answer:

Answer by John M
The experts can’t answer your question. In Japan, yesterday, they gave the tsunami warnings and had to sit and wait. Sometimes they don’t occur or their effect is minimal. But all you can do is sit and wait…

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3 Responses to “Q&A: How long before tsunami after earthquake happens?”

  • Vincent G says:

    The tsunami starts immediately, as it is caused by the movement of the bottom of the sea. How long it will take before it hits a specific point depends on how far that point is from the epicenter of the quake, and how many obstacles there are (it is not distance as the crow flies, it is distance as the wave moves).
    The wave propagates at the speed of a jet airliner across an ocean.

  • kirlia7755 says:

    Well, water will first contract back into the sea, leaving fish exposed. Around five to ten minutes later, a tsunami MAY strike. The 2004 boxing day tsunami lasted 1 1/2 hours, with a few waves hitting. AND till the next day, small waves still continue to strike.

  • lare says:

    The quake movement is what initiates the tsunami, so they start simultaneously. However the movenment travels through rock at a very high speed so that the quake can be detected at seismographs first. once 3 seismographs record the first arrival, the epicenter can be plotted and if under the ocean, a tsunami alert can be issued. where the quake is close to land as in Japan, the warning may only be a couple of minutes. The seismograph does not measure tsunami, only gives a warning that one could happen.

    to get more accurate tsunami information, sensors measuring sea surface movement have been placed at strategic locations. these verify a disturbance was generated and provide better arrival predictions at long distances from the quake as a tsunami can travel 1000s of miles and arrive many hours after the quake occured.

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