Geoscience Reference
In-Depth Information
Fig. 6.10
Limits of run-up of
the tsunami that swept Valdez
harbor following the March 27,
1964 Great Alaskan Earthquake.
A submarine landslide triggered
by the earthquake generated this
tsunami. The height of run-up
was 9 m. Photograph courtesy of
the World Data Center A for
solid earth geophysics and United
States National Geophysical Data
Center. Source Catalogue of
Disasters #B64C28-205
Table 6.2
Statistics on the run-up heights of the March 27, 1964
Alaskan Tsunami around the Pacific Ocean
Region
sand layer only 1-3 cm thick 200 m inland in a marsh south
of the city. Eleven people were killed in Crescent City by
the Alaskan Tsunami, most because they returned to low-
lying areas before the arrival of the fourth and largest wave.
As with the Chilean Tsunami, dispersion had greatly
reduced the height of the first couple of waves in the tsu-
nami wave train. The fourth wave was preceded by a general
withdrawal of water that left the inner harbor dry. The wave
then rapidly swept ashore, capsizing or beaching fishing
boats, destroying piers, and flooding thirty city blocks
backing the coast. Up to $8.8 million damage occurred in
this one city out of the $12 million damage along the west
coast of the United States. Elsewhere the wave swept
marinas, tore boats from moorings, and smashed piers.
Fortunately, the waves diminished in height significantly
before reaching San Francisco, where 10,000 people had
flocked to the coast to witness the arrival of this rare event.
Further south at San Diego, authorities were unable to clear
sightseers from the beaches.
Following the arrival of the wave in California, warning
sirens in Hawaii were sounded to alert the general popula-
tion to evacuate threatened areas. The first wave arrived at
Hilo 1.3 h after striking Crescent City. Along the exposed
shores of Hawaii, run-up averaged 2.3 m high, reaching a
maximum of 4.3 m at Waimea on the island of Oahu. Hilo,
which had been badly affected by the Chilean Tsunami
4 years beforehand, experienced a run-up of only 3 m in
height. Damage here was relatively minor because of the
long warning time before the arrival of the waves and
because much of the area affected by the Chilean Tsunami
had not been resettled. Over the next few hours, the wave
reached Japan and the South American coasts. In Japan, the
Average
height (m)
Maximum
height (m)
Range
(m)
Source area
11.0
67.0
0.3-67.0
Canada
4.8
9.8
1.4-9.8
Washington State
1.8
4.5
0.1-4.5
Oregon
2.8
4.3
0.3-4.3
California
1.6
4.3
0.3-4.3
Central America
0.4
2.4
0.1-2.4
South America
1.2
4.0
0.1-4.0
Hawaii
2.3
4.9
1.0-4.9
Pacific Islands
0.2
0.6
0.1-0.6
Japan
0.4
1.6
0.1-1.6
Australia-New
Zealand
0.2
0.2
-
Palmer Peninsula,
Antarctica
0.4
-
-
The tsunami became the largest historical tsunami disaster
to sweep the west coast of United States. Maximum wave
heights reached 4.3-4.5 m in all of the three coastal states of
Washington, Oregon, and California (Table
6.2
). Many
seaside towns received only 30 min warning of the wave's
arrival. Greatest damage occurred at Crescent City, Cali-
fornia, where bottom topography concentrated the wave's
energy. Crescent City has been affected by numerous tsu-
nami geologically. Coring of marshes in the area shows
evidence for at least six previous events, one of which laid
down a layer of sand 50 cm thick up to 500 m inland
(Peterson et al.
2013
). The Alaskan Tsunami laid down a
