The heights of runup of the tsunami are traced along the coastline 

 of Kodiak (Figure ^0 ) , along the seaboard of North America (Figures TT , 

 T8, 79 and 82) and around the islands of Hawaii (Figure 86). It is shown 

 that over a large stretch of coastline from Canada to Northern California 

 the highest tsunami waves arrived simultaneously with the crest of the 

 high spring tide. The combination produced widespread flooding and 

 inundation beyond the highest high tide mark. 



The tsunami waves arriving from the north and the astronomical tide 

 wave from the south penetrated the Columbia R:ver with the tsunami front 

 preceding the tide crest by about 1.5 hours. This meant that the highest 

 waves of the leading envelope of tsunami waves rode the crown of the tide 

 wave. There are several interesting features of this forced companionship 

 of big waves. It is shown, for instance, that the speed of advance of the 

 parasitic tsunami waves was at first less than, then later greater than, 

 that of the tide wave. Because of this and the progression of the tsunami 

 waves through the tide wave, the effective period of the tsunami waves 

 changes upriver from its value at the mouth. The tide wave itself en- 

 hances in amplitude before it decays inland from the mouth, presumably as 

 a result of pseudoresonance within the tidal region of the river. Further, 

 the heights of the first and second tsunami waves riding the tide crest 

 reverse their order of relative magnitude apparently because of a third 

 mode tidal oscillation in the estuary of 3.6 hours period, which has its 

 due effect in steepening the front of the astronomical tide itself during 

 its upriver run. 



h. Effects of the Main Tsunami and of Local Seismic Sea Waves 

 in Alaska 



The topography of the seabed off Kodiak City and the Naval Sta- 

 tion, Womens Bay, Kodiak, would have favored tsunami waves reaching Kodiak 

 City first from the northeast via the narrow channel between Near Island 

 and Kodiak. In the immediate neighborhood of Kodiak City the land sub- 

 sided 5.8 feet during the earthquake, and the sea apparently dropped with 

 it. Some inertial effects of the sea relative to land would have regis- 

 tered at once as an initial wave in this region, but conflicting opinion 

 was expressed by eyewitnesses regarding the occurrence of such a first 

 wave, closely following the earthquake. 



The evidence of eyewitnesses has been carefully weighed in relation 

 to an inferred marigram for Kodiak City (Figure 90), from which it is 

 concluded that the first wave was probably real and related to an initial 

 and purely local oscillation of water between Womens Bay and St. Pauls 

 Harbor. This oscillation could have been a seismic seiche created by the 

 southwestward thrust of the land during the earthquake. Owing to the 

 topography of the quasi-basin it was probably not very noticeable at 

 Kodiak City nor in Womens Bay, though prominent at the City Dock (Figure 

 89). 



Certain paradoxical features of eyewitness accounts of succeeding 

 waves are believed to have been resolved in this report. The first large 



354 



