Undoubtedly the constriction effect of Cook Inlet and the shoaling 

 effect of the Barren Islands would cause some reflection and scattering 

 of the tsunami energy so that waves penetrating into Cook Inlet might well 

 evolve at shorter periods. Their heights too would undergo considerable 

 reduction from energy loss at the entrance and energy dissipation through 

 refraction and diffraction into the wide basin of the lower Cook Inlet. 



Nevertheless, there are n\jmerous accounts of a tsunami having reached 

 Seldovia and Homer (Figure 130 ), near the end of the Kenai Peninsula, 

 within Cook Inlet. Many of these accounts (Waller, 1966; Chance, 1968; 

 Berg, et al, 196U) make it clear that large waves of short period (but 

 in the category of long waves) were generated during the earthquake. 

 The ground shaking and earth motions seem to have been predominantly in 

 a north-south or east-west direction (Chance, I968). Figure I6 suggests 

 that the landmass in the Seldovia-Homer region was displaced horizontally 

 to north-northwest by amounts varying from about 1 foot at Seldovia to 



5 feet at Homer, so that ground motion would have been favorable toward 

 inducing seismic seiches transversely across Kachemak Bay. 



Waller (1966) records that three different waves or large swells 

 were observed shortly after the quake on the Cook Inlet side of the spit 

 at Homer. The height of the waves was estimated to be approximately nine 

 feet. These waves apparently broke like a swell on the beach but caused 

 no damage. In Kachemak Bay there were also some petuliar wave formations 

 occurring during and after the quake. Several waves with heights of about 

 k feet rolled onto the north shore. All except one were observed to be 

 parallel to the north shore near Homer (Waller, I966). Since ground waves 

 were observed in motion in a north-south direction at Homer (Chance, I968), 

 some of these water waves evidently could have been excited by wave motion 

 of the bed of Kachemak Bay. There is little information about the period 

 of the water waves , but one report indicates waves of two minutes period 

 and 10 feet height were observed at the time of the earthquake (Coast 



6 Geodetic Survey, 196^+); another that waves of five minutes period and 

 U to 6 feet height occurred (Berg, et al, I96U). We may note that the 

 first three modes of free oscillation of the water body across Kachemak 

 Bay (near Homer) would be of the order of 30, 21, and 15 minutes, but 

 no information appears to exist suggesting that waves of this period 

 were observed. 



At about 9:30 p.m. a 20- foot wave arrived at Homer. The water rose 

 to k feet above the floor level in some buildings at the outer end of the 

 Homer Spit (Waller, I966). This could possibly be the same wave that was 

 reported from Perl Island at 8:U0 p.m. and the first major seismic sea 

 wave. Berg, et al (196I4) have drawn attention to the observation of the 

 wharfinger at Homer Spit that the first major effect of the earthquake on 

 the sea, other than the waves mentioned, was a withdrawal of water level 

 to it to 5 feet below normal beginning at about 6:10 p.m. Undoubtedly this 

 represented the advance of the negative tsunami wave producing a drawdown 

 as envisioned in Figure 36b. 



199 



