Ground breakage and associated effects in the Cook Inlet area, Alaska, resulting from the March 27, 1964, earthquake

Professional Paper 543-F
By:  and 



The great 1964 Alaska earthquake caused considerable ground breakage in the Cook Inlet area of south-central Alaska. The breakage occurred largely in thick deposits of unconsolidated sediments. The most important types of ground breakage were (1) fracturing or cracking and the extrusion of sand and gravel with ground water along fractures in various types of landforms, and (2) slumping and lateral extension of unconfined faces, particularly along delta fronts. The principal concentration of ground breakage within the area covered by this report was in a northeast-trending zone about 60 miles long and 6 miles wide in the northern part of the Kenai Lowland. The zone cut across diverse topography and stratigraphy. Cracks were as much as 30 feet across and 25 feet deep. Sand, gravel, and pieces of coal and lignite were extruded along many fissures. It is suggested that the disruption in this zone may be due to movement along a fault in the underlying Tertiary rocks. The outwash deltas of Tustumena and Skilak Lakes in the Kenai Lowland, of Eklutna Lake and Lake George in the Chugach Mountains, of Bradley Lake in the Kenai Mountains, and at the outlet of upper Beluga Lake at the base of the Alaska Range showed much slumping, as did the delta of the Susitna River. Parts of the flood plains of the Skilak River, Fox River, and Eagle River were extensively cracked. A few avalanches and slumps occurred along the coast of Cook Inlet in scattered localities. Some tidal flats were cracked. However, in view of the many thick sections of unconsolidated sediments and the abundance of steep slopes, the cracking was perhaps less than might have been expected. Observations along the coasts indicated changes in sea level which, although caused partly by compaction of unconsolidated sediments, may largely be attributed to crus1tal deformation accompanying the earthquake. Most of the Cook Inlet area was downwarped, although the northwest side of Cook Inlet may have been slightly unwarped. Maximum change in the Cook Inlet area was probably less than 6 feet. Little or no regional tilting was detected in the lake basins of Tustumena and Skilak Lakes.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Ground breakage and associated effects in the Cook Inlet area, Alaska, resulting from the March 27, 1964, earthquake
Series title Professional Paper
Series number 543
Chapter F
DOI 10.3133/pp543F
Year Published 1967
Language English
Publisher U.S. Government Printing Office
Publisher location Washington, D.C.
Contributing office(s) Menlo ParkCalif. Office-Earthquake Science Center
Description Report: v, 28 p.; 3 Plates: 19.81 x 30.95 inches or smaller
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title The Alaska earthquake, March 27, 1964: Regional effects (Professional Paper 543)
Country United States
State Alaska
Other Geospatial Cook Inlet
Google Analytic Metrics Metrics page
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