Book Description

"The purpose of this study is to evaluate the tsunami of Good Friday196k. The evaluation is directed to an engineering view of the causes,effects, and future protective measures. A secondary purpose is to evaluate the oceanographic and geophysical nature of tsunami generation.Based on the literature of earlier investigators and on field investigation by the authors, the study gives a picture of what occurred.Analyses by the authors also suggest an explanation of how it occurred.Started nearly two years after the event, the study had the advantage of collecting data from a great number of sources - sources that would not have been available much closer to the event. A disadvantage was that vital engineering evidence concerning structural damage was lost during cleanup and reconstruction.Nature of the earth dislocation is described and related to the generation, propagation, and dispersion of the main tsunami waves. Itis inferred that this earthquake (as perhaps many great earthquakes) was triggered by the lunisolar forces on the earth's crust at syzygy and by the moment-arm forces of local spring tide differentials. The complex tectonic movements may, for simplification, be imagined as a gigantic wave-paddle that pushed an initial wave 10 to 20 meters high along a front of 650 kilometers. Propagation of this enormous wave is followed-to Canada, Washington, Oregon, and California, to Hawaii, Russia, Japan,and New Zealand, even to Tierra del Fuego and Antarctica.Detailed studies of the main tsunami and local seismic sea waves are given for damaged areas in Alaska, especially those in Prince William Sound. Similar studies are presented for a'"as in Canada, Washington,Oregon and California. In addition to the wave analysis for each place,an engineering evaluation is presented for severely damaged areas.Included are marigrams of component waves and oscillations for manyplaces reached by the tsunami, based on a subjective analysis of tide gage records. These analyses relate the tsunami waves to local bay andshelf oscill ations, and to the local tides"--Page iii.