1964 Good Friday
The Aleutian Islands and Trench
across the northern Pacific Ocean between Kamchatka
in Siberia and south central Alaska.
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- In this area the Pacific Plate moves northwestward
at a rate of approximately five to seven centimeters
(2 to 2.75 inches) per year.(2)
- At the same time it is
or pulled down and under the North
- This causes some of the southern
Alaskan crust to be
- Some areas along the coast
while others are
- After tens to thousands
of years the stress in the rocks
becomes too much and they break, causing
a sudden slipping of the earthís crust.
- This breaking and slipping of the rocks is called an
- The surface along which two blocks of rock slip
is called a fault.
Some faults are small and some are 1000's of
kilometers long. The fault in Alaska is 1000's of kilometers
long and divides two large plates
of rock called the Pacific Plate
and the North American Plate.
- In the case of the Alaskan earthquake,
, place under the surface of the Earth where
the earthquake actually occurred, was
(18.6 miles) deep.
- This is a shallow earthquake.
It means that a lot of the energy that the earthquake
produced was felt at the Earthís surface, over
1,300,000 square kilometers
(over 500,000 square miles)
throughout Alaska, parts of Canada, and the
southern part of Washington State.(2)
- In addition,
a magnitude of 8.6
it had the same amount of energy as
would be produced by detonating one billion
tons of TNT.(3) It also had one hundred
times more ground movement than the earthquake
in Northridge, CA that took place on January 17, 1994.(4)
This earthquake caused the Earth to
, or break,eight hundred kilometers
(497 miles)along a fault that runs
parallel to the Aleutian Trench.(1) Rupture extended from
Prince William Sound to the southwest end of Kodiak Island.
This rupture caused the sea floor at Montague Island in
Prince Williamís Sound to uplift 4.8 meters (16ft)(4)
and generated a powerful
which was responsible for 90% of the death
and destruction caused by this earthquake.
Within twenty-four hours of the quake,
a zone two hundred fifty kilometers (155 mi) wide
and eight hundred kilometers (497 miles) long had
experienced twenty eight
smaller earthquakes after the main one, ten of which
were over magnitude 6.0.(3)
Learn more the 1964 Good Friday Great Alaskan Earthquake
Other sites of interest:
Windows to Arizona Geology
United States Geological Survey Report on
With many thanks to the following sources:
Macklin, T. for
photos by his brother.
1) Bolt, B., 1993, Earthquakes. W.H.Freeman and Company.
2) Christensen, D.
3) Lutgens, F. and Tarbeck, E., 1995, Essentials in Geology. Prentice Hall.
4) Pipkin, B. and Trent, D., 1997, Geology and the Environment. West/Wadsworth.
5) Sokolowski, T.
6) United States Geological Survey.
Page by Nievita Bueno Hartness
Last Updated 12/06/2001