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PACIFIC SCIENCE, Vol. XXI, July 1967 
be the highest, at least within the generating 
area. At Uzinki, Kodiak City, Women’s Bay, 
and elsewhere on the island of Kodiak, how- 
ever, the third and fourth waves were the high- 
est. A theory of generation from a single 
pattern of crustal deformation is therefore not 
satisfactory here. Such factors as reflection from 
coastal boundaries, wave interaction, and reso- 
nance should be taken into consideration. 
Slumps or avalanches, similar to the ones that 
occurred in Prince William Sound, are usually 
localized; they can produce no large tsunamis 
that would travel across wide portions of the 
ocean. According to Wiegel (1954), not more 
than 2% of the potential energy of a falling or 
sliding body is converted into wave energy. In 
Prince William Sound, however, slumping and 
sliding when added to tectonic movements cre- 
ated tsunami waves of very large energy, but 
their effect was catastrophic only locally; very 
little of the energy escaped the Sound. 
SUMMARY AND CONCLUSIONS 
The Alaska earthquake of March 27, 1964 
affected an area of approximately 215,000 km 2 , 
extending from the Wrangell Mountains at the 
northeast to the Trinity Islands in the south- 
west, and from the west side of Shelikof Strait 
and Cook Inlet east to the vicinity of the Bering 
Glacier. 
Geologic evidence has revealed a dipole pat- 
tern of positive and negative tectonic move- j 
ments resulting from this earthquake. The area 
of subsidence covers approximately 110,000 km 2 
and the volume of crust that has been depressed 
below its pre-earthquake level is about 115 km 3 . 
The area of uplift covers about 105,000 km 2 
and includes the southern and eastern parts of 
Prince William Sound, the coastal area as far 
east as the Bering Glacier, and a great part of 
the continental shelf and slope bordering the 
Gulf of Alaska. 
The seaward limits of the area affected by 
the Alaska earthquake and the tsunami-generat- 
ing area were determined by means of a series 
of wave refraction diagrams as shown in Figure 
5, based on Snell’s Law of Refraction. The 
tsunami-generating area covers 140,000 km 2 
and includes the whole of the region of uplift 
and part of the region of subsidence. It extends 
from the Trinity Islands to the Bering Glacier 
and includes Shelikof Strait, Cook Inlet, and 
the continental shelf bordering the Gulf of 
Alaska to a depth of approximately 200 m. The 
total volume of displaced material in the tsu- 
nami-generating area was estimated to be 120 
km 3 , and the energy associated with the tsunami 
was calculated to be in the order of 6 X 10 21 
ergs. 
As a result of this work the following con- 
clusions are drawn: 
Fig. 5. Diagram of wave fronts refracted toward the earthquake area from Attu Island ( dashed line), 
Adak Island ( solid line), and Unalaska Island ( dotted line). 
