ABSTRACT 



The purpose of this study is to evaluate the tsunami of Good Friday 

 196^+. 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 investi- 

 gation 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 advan- 

 tage 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. It 

 is 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 areas 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 many 

 places reached by the tsunami, based on a subjective analysis of tide 

 gage records. These analyses relate the tsunami waves to local bay and 

 shelf oscillations, and to the local tides. 



For convenience, the study is summarized in Section VII, and con- 

 clusions are presented in Sections VIII and IX. 



FOREWORD 



Although large tsunamis are relatively rare occurrences, they cause 

 major damage when they do occur. The Alaskan tsunami of March 196U gene- 

 rated a great deal of interest in the scientific community as a whole, and 

 in various Federal agencies concerned with tsunami warning and protection, 

 including the U. S. Army Corps of Engineers which is particularly involved 

 in the planning and design of protective structures to prevent or mitigate 

 damage in harbors and along shores. This general scientific interest was 

 also stimulated by the establishment of a National Academy of Sciences 

 Committee on the Alaska Earthquake. Two panels of that Committee, the 



