Figure 27 tends to place the flanking wave at the origin almost 

 exactly along the line of the Aleutian Trench as found by Van Dorn. On 

 the other hand, it suggests a strong concentration of energy emanating 

 from what must be considered the end of the fault along the line of the 

 Aleutian Trench at a point approximately due southeast of the south- 

 western tip of Kodiak Island near the Trinity Islands. In regard to 

 the southwestern extremity, this is in fair agreement with Pararas- 

 Carayannis (Figure 26b), and would suggest that the total fault length 

 L - 800 kilometers proposed by Press and Jackson, and Furiomoto is not 

 unreasonable, assuming its penetration as far as Valdez . 



From Figures 25, 26, and 27 we infer that the tsunami source area 

 was roughly rectangular and about 700 kilometers long by 200 kilometers 

 wide. The corresponding source diameter S yielding the same area is 

 about U25 kilometers. Plotted against earthquake magnitude in Figure 28, 

 this is found to be in reasonable accord with Japanese data of lida (1958) 

 and of Watanabe (196U). An empirical relationship which would provide 

 a reasonable fit to these data is 



log S - (2/3) M - 3 (3) 



for S in kilometers and is similar to the relationship proposed by 

 Wilson, et al, (1962). 



7. Speculation on the Cause of the Earthquake and the Earthquake 

 Mechanism 



In the Introduction we remarked that the earthquake occurred 

 "mercifully" at low tide and that this fact, together with the uplift of 

 the land over a vast area greatly mitigated the damage potential of the 

 tsunami. We shall now advance the concept that this interrelationship 

 necessarily had to occur as it did. 



In all the literature about the Alaskan earthquake, we have found 

 nothing to suggest that it was remarkable that the earthquake occurred on 

 Good Friday and at a time close to sunset. We shall suggest that these 

 facts also were part of the interlocked relationship. In advancing the 

 concepts that follow, the first author (Wilson) does so somewhat diffi- 

 dently, knowing that he trespasses in an area of uncertain knowledge. 

 If the ideas lack substance, he trusts that he will be forgiven for 

 letting a spirit of enquiry outrun the formal bounds of study. But, 

 if some element of truth is found, the implications could have value 

 in furthering the prediction of earthquakes and of tsunamis. 



That the earthquake occurred on Good Friday, March 27, 196^, 

 establishes that the moon was at the full; that the earth, sun and moon 

 were in conjunction; that the oceanic tides were at the spring or greatest 

 range and that the earth tides were at their strongest. Moreover, the 

 earth had just passed the vernal equinox (March 20) on its orbital path 

 in the plane of the ecliptic (Figure 29). We are tempted to ask whether 



39 



