Section I. INTRODUCTION 



At 5:36 p.m. local time on Good Friday, March 27, 196U, Alaska was 

 rocked by a great earthquake with an estimated magnitude M - Q.k to 8.6 

 on the Richter Scale. The strain energy released was more than half as 

 much again as that released by the earthquake of 1906 at San Francisco 

 (M - 8.3) or a quarter more than that released by the Chile earthquake 

 of 196Q (M = 8.i+). 



The epicenter of the Alaskan earthquake occurred apparently in the 

 remote Chugach Mountains at latitude 6l.l° N. , longitude 1^7.7° W. , ±15 

 kilometers (Hansen, et al, 1966), but, according to this definition, it 

 could have occurred as easily in Unakwik Inlet, or on tributary arms of 

 Unakwik Inlet, or the neighboring College Fjord to the west of Prince 

 William Sound (Figure l). Main particulars of the epicenter location of 

 the earthquake focal depth, magnitude, and orientation are contained in 

 Table I, from which it is evident that estimates of longitude reported by 

 various authorities vary from li+7.5° to 1^+7.8°, a difference latitudinally 

 of about 9 nautical miles . 



The focal depth of the earthquake appears to have been comparatively 

 shallow (20-50 kilometers) and for the earthquake magnitude this conforms 

 to the statistical trend reported by Gutenberg and Richter (l95^), and as 

 summarized by Wilson, et al (1962). The hypocenter has evidence of being 

 at or near the elbow point of an almost right-angled faulting system that 

 characterizes the geological structure of the Alaskan landmass. An immense 

 movement of the land, horizontally and vertically, resulted, covering a 

 large extent of south central Alaska and the Continental Shelf offshore. 



The impact of this movement on the sea was registered in many ways. 

 The total movement along a front of about 8OO kilometers , within the short 

 time of U or 5 minutes, triggered a train of tsunami waves that swept to 

 the far reaches of the Pacific Ocean. Locally, in Prince William Sound 

 and in the complex fjord-like indentations of the coast, seiches were set 

 in motion by the tilting of the sea bed, and devastating waves were gene- 

 rated by submarine slumping of unstable glacial deltas and by landslides 

 from the steep sides of the fjords into the sounds. 



Inside Prince William Sound the violent local commotion of water in 

 the maze of gulfs and bays that encompass the Sound in an almost land- 

 locked circuit completely razed the waterfronts of Valdez and Whittier 

 and virtually wiped out the Indian village of Chenaga. Cordova on the 

 southeast side of the Sound was spared a far worse fate by the uplifting 

 of the land. 



Outside Prince William Sound the tsunami assailed Seward on the 

 southwest side of the Kenai Peninsula and destroyed part of Kodiak City 

 and its residential environs. The great waves raced on to the west coast 

 of Canada and the United States and demolished parts of Port Alberni , 

 Canada, and Crescent City, California. They reached the Hawaiian Islands 



