The inference of this report is that the explanation could be twofold; 

 first, that a "caustic" concentration of high energy bearing on Crescent 

 City may have originated from as far back as the tsunami source region, 

 and second, that resonance of a binodal form of shelf oscillation may 

 have been promoted by the third harmonic of the tsunami waves (To - 36 

 minutes). In this case a mode of oscillation of the Continental Shelf 

 which could have responded to the second harmonic of the tsunami waves 

 (T2 - 5^ minutes) was not excited, presumably because of the absence of 

 this stimulation. 



The response of Monterey Bay, California, to the tsunami is perhaps 

 typical of many another indented coastline of concave shape. It appears 

 that the bay is capable of functioning to some extent as the quadrant of 

 a circular basin with a paraboloidal bed. Many of the dominant periods 

 of oscillation recorded in the area appear to agree with the numerous 

 modes in which such a circular basin can oscillate within the limitation 

 that a node must lie at the edge of the Continental Shelf or at the mouth 

 of the bay. At Crescent City the Continental Shelf and coast approximate 

 a semi-ellipsoidal bowl, and the permissible modes of oscillation of the 

 bowl that describe modes for the shelf require a node along the major 

 axis (or Continental Shelf edge). 



Along the narrow Continental Shelf and in the deep fjords off the 

 Canadian coast, the tsunami waves were enabled to reach into the inlets 

 before feeling the effects of rapid changes of depth. The effects at 

 Port Alberni, Canada, were phenomenal. Alberni Inlet is a long canal-like 

 fjord with a shelving bed from deep water at its mouth in Barkley Sound. 

 It is found to have a funamental period of free oscillation of about 

 1.85 hours, and therefore acted as a natural resonator for the reception 

 of the tsunami waves. It is estimated that amplification of the waves 

 from the mouth to the head of the Inlet may have involved a factor of 

 about 10 . 



At Lyttelton, New Zealand, where the long waves were of remarkably 

 pure form, it would seem that the influence of local resonance is the 

 cause also of a change in shape of the beat of the tsunami wave system. 

 This appears to have been brought about by a greater degree of pseudo- 

 resonant amplification of later waves than leading waves, ascribed to 

 the effect of the Port Lyttelton Inlet. 



The heights and periods of what appear to be the main constituents 

 of the tsunami waves registered by tide gages at a selected number of 

 stations around the Pacific Ocean are summarized in Table III (p. lOO) . 



In a rather qualitative way it is shown that the heights H of the 

 fundamental tsunami waves (T - 1.8 hours) appear to decay with distance r 

 from their origin according to the laws H °^ r -^' -* or H °^ r ' , at all 

 receiving stations along the seaboard of the Americas, toward which the 

 waves would have had essentially a one-dimensional (nonradial) type of 

 propagation. The law H °^ r-*-'-^ applies best to data for stations along 

 the North American coast and H <^ r"-'-'^ for South American stations that 



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