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[Physltest] [Phys-L] Re: earthquake



At 09:10 AM 1/3/2005, Chuck Britton, you wrote:
///
A wrong impression is given by this Tulane site by 'implying' that
the tsunami consists of DEEP water waves while 'out to sea'.

It is important to note that the wavelength of the tsunami is GREATER
than the depth of the ocean. These are SHALLOW water waves that are
traveling across the oceans!!!!
///
Deep water waves have an amplitude that is quite comparable to the wavelength.
///

I expect Chuck would be happier with these selected quotes,
taken from the same URL:

A tsunami is a very long-wavelength wave of water that is generated by
sudden displacement of the seafloor or disruption of any body of standing
water.
///
Normal ocean waves have wavelengths of about 100 meters.
Tsunami have much longer wavelengths, usually measured
in kilometers and up to 200 kilometers.
///
Velocities of normal ocean waves are about 90 km/hr while tsunami
have velocities up to 950 km/hr (about as fast as jet airplanes)
///
Tsunami are characterized as shallow-water waves.
///
A tsunami can have a period in the range of ten minutes to two hours and
wavelengths greater than 500 km.
A wave is characterized as a shallow-water wave when the ratio of the
water depth and wavelength is very small. The velocity of a shallow-water
wave is also equal to the square root of the product of the acceleration
of gravity, g, (980cm/sec/sec) and the depth of the water, d.

V=Ög * d

The rate at which a wave loses its energy is inversely related to its
wavelength.
Since a tsunami has a very large wavelength, it will lose little energy as it
propagates
///

Brian W


Brian Whatcott Altus OK Eureka!
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