Comparison of the period sequence in Equation (U8) with that of 

 quation (Ut) suggests that the Valdez emhayment would not provide reso- 

 ance for the expected fundamental period of the tsunami waves generated 

 t the mouth of Prince William Sound. However, in view of the impli- 

 ation that the Sound might well develop oscillations corresponding to 

 tie higher modes of its triangular shape, some degree of resonance or 

 seudoresonance could amplify the effects of oscillations of period less 

 tian 50 minutes. 



Figure 161 gives the results of seismic reflection profiles of the 

 aldez embayment obtained in field surveys since the earthquake (Von 

 iiene, et al, 1967). The basement rock profile has an average depth 

 Q Valdez Arm of about 1,200 feet. It is deeper (about 1,600 feet) in 

 Drt Valdez. In Valdez Narrows, the rock forms a sill which is vlrtu- 

 Lly free of sediments. Owing to the elbow bend formed between Valdez 

 rm and Port Valdez, the latter is capable of functioning as an effec- 

 ively closed basin for any water oscillations generated within it. 

 le profile AB in Figure 161 is not quite complete in showing the rise 

 f sediments beyond B. The water depth profile, however, may reasonably 

 ill be taken as being semiparabolic over the basin length of 11.35 

 autical miles, with its maximum depth of 85O feet at the west end. 



The manner in which this basin would oscillate by itself longi- 

 idinally may be found by considering it just half of its mirror-image 

 isin. Applicable modes from the solution of the double basin are 

 ily those that yield an antinode at the center. From Wilson (1966), 

 ;ien, we find the fundamental and second mode periods of oscillation 

 longitudinally) for Port Valdez to be 



, (i) T-| =17.8 minutes 1 



r ^^^^ 



(ii) Tg - 9.8 minutes 



There is no tide record for Valdez Harbor. As at Seward, we are 

 jpendent on accounts of eyewitnesses and the studies of other investi- 

 ators for an interpretation of what happened. We shall refer to many 

 ■jurces of information, notably, Grantz, et al (196U); Brown (196U); 

 brg, et al (196I+); Coast & Geodetic Survey (196U); Denner (196I+); 

 lafker and Mayo (1965); Spaeth and Berkman (1965, 196?); Coulter and 

 ^I'gliaccio (1966); and also unpublished materials to be cited. 



Valdez is situated at the eastern end of Port Valdez on the seaward 

 fige of a large outwash delta composed of a thick section of saturated 

 E.lty sand and gravel. Its general location is shown in Figure 16O and 

 Citails of the layout of the city and harbor are given in the prequake 

 {.an, Figure l62. The town was entirely contained within a V-shaped 

 livee which prevented inundation from the frequent rampages of the Valdez 

 F,,ver draining from the Valdez Glacier. Figure l63 shows the appearance 

 t" the waterfront before the development of the small boat harbor in the 

 t.dal zone area between the north and south arms of the docks . 



Text resumes on page 260 

 255 



