On
July 12, 1993 a magnitude 7.8 earthquake in the Sea of
Japan produced tsunami that totally destroyed the southern
half of Okushiri Island. Waves were greater than 30 feet
and some could have been 100 feet. The earthquake was
about 50 miles offshore and the tsunami arrived within
minutes. 120 people died.
The states most
at risk for Tsunami are California, Hawaii, Oregon and
Washington. Hawaii is at greatest risk and they have about
1 tsunami a year and a dangerous tsunami about every 7
years.
On March 28, 1964
an extremely large earthquake (magnitude 8.4) struck Alaska.
It caused tsunami waves that were very destructive in
southeastern Alaska, in Vancouver Island, Canada, and
in the States of Washington, California and Hawaii. Waves
ranged in size from 6 to 21 feet. The tsunami killed more
than 120 people and damages costing more than $106 million.
It was the costliest tsunami ever to strike the Western
United States and Canada.
Although a large
asteroid impact is highly unlikely, scientists studying
the possibility have decided that a moderately large asteroid
or about 5-6 km in diameter falling in the middle of the
Atlantic Ocean, would generate a tsunami that would travel
all the way to the Appalachian Mountains in the upper
two-thirds of the United States. Coastal cities would
be wiped out by such a tsunami.
Nuclear explosions
could possible create tsunami but none have ever been
generated from testing yet. Furthermore, such testing
is currently banned by international treaty.
