Earth Science Hawaii... The Ticking Time bomb!

Discussion in 'Earth Science' started by JcMinJapan, Sep 12, 2004.

  1. JcMinJapan

    JcMinJapan Premium Member

    The "crack" on the Big Island of Hawaii from what I have seen is showing signs of slowly getting large. Now, if this is true above, a large portion of the western side of the big Island will fall into the ocean and cause a huge mega tsunami, that I would gess would devistate Asutralia, New Zealand, The west coast of America, Japan, Phillipines, etc etc. The whole Pacific ocean would be torn up I guess.

    any thoughts, or has anyone heard of this before?

    Map References of USGS Hawai`i Geologic and Thematic Maps
  2. Cinderloft

    Cinderloft Premium Member

    For some reason I just can not visualize how it could create a tsunami in my head. Granted it is a big piece of rock falling in the ocean, but to me, that ocean is pretty friggen huge. I cant see how it would maintain height and momentum and be able to cross thousands of miles of ocean still intact (even partially) and cause devestation. I see it as going for a few miles, and slowly petering out, running out of steam. I do not know much about a tsunamis mechanics however, but this has always puzzled me.
  3. JcMinJapan

    JcMinJapan Premium Member

    Tsunamis are unlike wind-generated waves, which many of us may have observed on a local lake or at a coastal beach, in that they are characterized as shallow-water waves, with long periods and wave lengths. The wind-generated swell one sees at a California beach, for example, spawned by a storm out in the Pacific and rhythmically rolling in, one wave after another, might have a period of about 10 seconds and a wave length of 150 m. A tsunami, on the other hand, can have a wavelength in excess of 100 km and period on the order of one hour.
    As a result of their long wave lengths, tsunamis behave as shallow-water waves. A wave becomes a shallow-water wave when the ratio between the water depth and its wave length gets very small. Shallow-water waves move at a speed that is equal to the square root of the product of the acceleration of gravity (9.8 m/s/s) and the water depth - let's see what this implies: In the Pacific Ocean, where the typical water depth is about 4000 m, a tsunami travels at about 200 m/s, or over 700 km/hr. Because the rate at which a wave loses its energy is inversely related to its wave length, tsunamis not only propagate at high speeds, they can also travel great, transoceanic distances with limited energy losses.

    On the above link, there is also a movie that shows how it can happen. Also, the movie covers a tsunami that happened in Chile and killed 200 in Japan. Quite interesting info here.