"The great earthquake of March 27, 1964, in south-central Alaska was accompanied by regional tectonic warping that caused both extensive subsidence and uplift relative to sea level. During the months after the earthquake geologists made a concerted search for evidence of surface faulting. A U.S. Geological Survey field party headed by the writer found two reverse faults on southwestern Montague Island in Prince William Sound through combined air reconnaissance and studies of shoreline displacements. Although it is assumed that the fault displacements occurred during the main shock, or possibly during some of the subsequent large aftershocks, there were no eyewitnesses to fix the precise time of rupture."
Geological Survey Professional Paper No. 543-G
U.S. Geological Survey: http://www,usgs.gov/