Subject: Hawaii earthquakes

If a large eq-7.8 occurs south of hawaii, do the natives think it bodes ill for them?

    I guess you are referring to the Ms=7.8 Chile earthquake of July 30. The answer is "yes." Chilean earthquakes have a long history of causing damaging tsunamis in the Hawaiian Islands (69 people were killed in Hilo by the tsunami of 1960, for example). With the tsunami warning system, however, we get a very good idea of the size of waves from that direction. We also get plenty of time to react - the travel time of a tsunami from Chile to Hawaii is over fourteen hours.
    Immediately after Saturday's earthquake, the Pacific Tsunami Warning Center near Honolulu went on alert. Within an hour of the event they knew that the depth was probably greater than 50 kilometers, which means that the earthquake was very unlikely to have changed the shape of the seafloor enough to generate big waves. Soon after that came reports that the highest waves along the Chile coast were 1.2 meters. That's too small for the rest of the Pacific to worry about, so a tsunami warning was never issued. Tide gauge reports from French Polynesia verified that the waves were small.
    When the waves finally reached Hawaii they had a maximum height (at Hilo) of 70 centimeters.

Gerard Fryer
Hawaii Institute of Geophysics and Planetology
University of Hawaii, Honolulu HI 96822

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