igob.] SEE— THE CAUSE OF EARTHQUAKES. 365 



of the sea near the shore. At 9:15 a. m. Vice Admiral Putiatin on 

 board the Russian frigate Diana noted very powerful shocks of an 

 earthquake, and a little before ten o'clock a huge wave was seen 

 coming which quickly overflowed the city. Major Dutton remarks 

 that the time here involved, and the known speed of propagation of 

 such a wave, indicates that it originated over 100 miles from the 

 shore, in the Tuscarora trough, where the depth attained is over 

 4,000 fathoms. 



If it originated so far away, it might have resulted from the 

 sinking of the sea bottom, as in the Arica and Iquique waves, the 

 withdrawal of the sea when the waters rush into the sink becoming 

 so nearly insensible at the great distance of Simoda as to escape 

 notice in the bay. But a more probable explanation is that the sea 

 bottom just east of the Tuscarora deep was heaved up into a ridge 

 with elevation of 20, 30, or 50 feet. This would produce the 

 great wave which so suddenly appeared to overwhelm the city. 

 In this case there would be no preliminary recession of the water 

 whatever, and the wave would come without the least warning, as 

 appears to have been the case. 



In case the wave originated by a subsidence of the bottom of 

 that trough, a slight withdrawal of the water from shore should 

 have been noticed even at that great distance; but if the upheaval 

 occurred beyond the trough, the greater inrush of water from that 

 side may have obscured the slight recession which otherwise might be 

 expected at Simoda. The upheaval is conceivable in the manner 

 we have described, either with or without subsidence of the bed, 

 and ordinarily the disturbance might be on either side of the 

 trough ; but in this case the time shows that the uplift probably was 

 beyond the trough. 



§41. Another explanation of sea waves on the hypothesis of 

 submarine eruptions. 



The only other rational way of explaining these great sea waves 

 is by means of the uprush following the explosion of a submarine 

 volcano. We consider his explanation much less satisfactory than 

 that already given, but it is undeniable that in certain cases it might 

 account for both classes of sea waves, especially where the water is 

 deep and we can suppose the volcano to be upheaved near shore and 

 of large size. 



