6. Tsunami Waves and Damage at Cordova, Prince William Sound 



Cordova, on the south side of the Orca Inlet, at the mouth of 

 ince William Sound, is an important fishing community. The bathymetry 

 this region is shown in Figure 200. Unlike other towns of Prince 

 lliam Sound, Cordova has shallow access routes which militate against 

 s development as an important terminal for oceangoing vessels. A 

 tailed map of the harbor and waterfront area of Cordova is shown in 

 gure 201. 



The town, situated mostly on bedrock, suffered relatively little 

 nage from earth tremors. One exception was the city dock, a timber 

 ructure, that was severely shaken by the earthquake. Loosened pilings 

 aned askew, and canneries and several other buildings adjacent to the 

 2k were pulled 6 to 12 inches away from the dock (Chance, 1968). The 

 ^n was elevated approximately 6 feet due to the regional tectonic up- 

 ft. This upheaval caused inconvenience to many shore facilities such 



canneries, and posed a major problem of dredging access routes through 

 ^ly created shoal areas (Hansen, et al , I966). The canneries had to 

 tend their docks an average of 110 feet to reach water depths equal 



those prevailing prior to the earthquake (Eckel, 1967)- 



Most of the damage to structures at Cordova and vicinity was caused 

 tsunamis. It is difficult from eyewitness accounts to get a clear 

 ::ture of the wave sequence at Cordova. Nevertheless, an inferred 

 rigram has been compiled in Figure 202. 



Immediately after the earthquake the water started to recede from 

 5 harbor leaving the boats grounded. Several subsequent long waves 

 peatedly grounded the boats in the small-boat harbor. The periods of 

 e waves have been estimated by different persons to have been from 1/2 

 ar to 1 hour. Sufficient time has not been available in this study 

 r estimating the oscillating characteristics of the embayment . 



A wave reported at about 7:00 p.m. was apparently from h to 10 feet 

 gh. A large recession to about 2k feet below MLLW occurred at 8:20 as 

 corded by the Coast Guard Cutter Sedge (see below). Another big wave 

 llowed at about 9:00. No specific height was assigned to this wave. 



about 10:15 the water was reported to be 10 feet below MLLW, after 

 ich it reached a high level of about 13 feet above MLLW. The only wave 

 at rose above the former high water line came in at about 1:00 a.m. 

 is wave rose to a level about 3 feet over the dock, or about 20 feet 

 ove MLLW. According to tide tables, high tide occurred at 12:3U a.m. 



the night of the earthquake and the predicted height was 13 feet 

 ove MLLW. 



This last wave lifted the dock, and set it off to the side of its 

 pporting pilings. The water penetrated some 300 feet inland in the 

 rbor area, damaged waterfront buildings, and carried away several small 

 uses at Point Whitshed (Figure 200). These houses were floated toward 

 rdova City; one knocked the radio tower off its pedestal. The tower. 



311 



