Tsunamis savagely attack coastlines, devastating property and
causing loss of life. The cause may be earthquakes, landslides,
volcanic eruptions, explosions, and even the impact of cosmic
bodies, such as meteorites.
Today we are fortunate that there are warning systems in place.
We have a bit of time to evacuate dangerous areas.
Normal waves we see at the beach or on lakes are wind-generated.
Their characterizes as shallow-water waves are with long periods
and wave lengths, rhythmically rolling in, one wave after another,
might have a period of about 10 seconds and a wave length of 150
meters. A tsunami, on the other hand, can have a wavelength in
excess of 100 km and period on the order of one hour.
A wave's energy will be constant, dependent on its speed and
height. The speed will slow as the wave travels into shallower
water but its height will grow. Because of this shoaling effect,
a tsunami, imperceptible at sea, may grow to be several meters or
more in height near the coast. When it finally reaches the coast,
a tsunami may appear as a rapidly rising or falling tide, a series
of breaking waves, or even a wall of water.
What can you do? In general, if you think a tsunami may be coming,
the ground shakes under your feet or you hear there is a warning,
repeat the warning to everyone and then quickly get to higher
ground. Remember that all coastal areas can be struck by tsunamis;
that they consist of a series of waves, and that the first wave may
not be the largest. The danger from a tsunami can last for several
hours after the arrival of the first wave. Do not hurry back into an
area. The next wave may be coming, and it can move faster than a
person can run.
If you are on a boat, remember that tsunami wave activity is
imperceptible in the open ocean. Do not return to port. Tsunamis
can cause rapid changes in water level and unpredictable dangerous
currents in harbors and ports. If possible, contact the harbor
authority before returning to port.
Make evacuation plans. Plan at least two evacuation routes since
roads may become blocked or closed. Develop an emergency
communication plan, for your family, neighbors and co-workers.
If family members are separated from one another because of
a tidalwave, have a plan for getting back together. Use an
out-of-area relative or friend to serve as the "family
contact" after a disaster. Often it is easier to call long
distance than get through to a local number (lines down,
congested, etc.). Every family member should know the name,
address, and phone number of the contact person.
Some fine sources of information are:
Last Modified: Nov. 15, 1999 by Fred Klusmann You are Visitor #
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