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Subject: Local Earthquakes

I understand that the plate upon which the islands are apart of experiences earthquakes daily. If this is true, how come we do not feel them?

    The Hawaiian Islands are on the Pacific Plate, which extends from the East Pacific Rise to Japan, a distance of about nine thousand miles. There are abundant earthquakes all around the edge of the plate (there are about four magnitude 5 earthquakes on the margins of the Pacific plate every day, and about one magnitude 6 event every week), but for even the largest earthquakes it is very rare for people to feel them more than a thousand miles away. (One notable exception was the recent Bolivian earthquake, which was felt as far away as Montreal, but that was unusually deep.)
    There are also earthquakes in Hawaii, mainly beneath the Big Island, which is as seismically active as anywhere in the U.S. If you lived in Hilo you'd probably feel one earthquake a month. On Oahu, you'll feel two or three a year if you are sensitive. Big earthquakes beneath the Big Island (anything larger than magnitude 6) are felt very well in Honolulu.

Gerard Fryer
Hawaii Institute of Geophysics and Planetology
University of Hawaii


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