THE CAUSE OF EARTHQUAKES, MOUNTAIN FORMA- 

 TION AND KINDRED PHENOMENA CONNECTED 

 WITH THE PHYSICS OF THE EARTH. 



By T. J. J. SEE, A.M., Lt.M., Sc.M. (Missou.), A.M., Ph.D. (Berol.), 



Professor of Mathematics, U. S. Navy, in Charge of the Naval 

 Observatory^ Mare Island, California. 



(Read October ig, igo6.) 



I. General Considerations on the Cause of Earthquakes. 



§ I. Introduction. 



The great San Francisco earthquake of April i8, 1906, presented 

 certain remarkable characteristics which immediately became a sub- 

 ject of investigation on the part of men of science resident in this 

 part of the United States. One very striking feature of this earth- 

 quake vv^as the conspicuous rotatory motion of the earth particle; 

 and another was the long duration of the disturbance. The rotatory 

 motion appeared so remarkable and so difficult to reconcile with 

 theories very generally held by geologists and seismologists that it 

 seemed worth while to make a somewhat comprehensive survey of 

 the general subject of earthquakes, in the hope of reaching a better 

 understanding of the cause of these phenomena. And as the details 

 of this particular earthquake will be fully treated by others,^ the 

 result of the present inquiry- into the physical cause of earthquakes 



^ The Committee of Investigation appointed by the Governor of Cali- 

 fornia : Professors A. C. Lawson, George Davidson, A. O. Lenschner, G. K. 

 Gilbert, W. W. Campbell, H. F. Ried, J. C. Branner, Chas. Burkhalter. 

 Investigations are being made also by Professor Omori of the Imperial 

 University of Tokio, Messrs. Otto Von Geldern, Luther Wagoner, and Mr. 

 Hoehl of the American Society of Civil Engineers, and perhaps by others. 



^Rear Admiral H. H. Rousseau, U. S. Navy, Chief of the Bureau of 

 Yards and Docks, has read this paper throughout, and made a number of 

 suggestions which proved valuable. The independent judgment of an experi- 

 enced engineer was felt to be no inconsiderable advantage in weighing some 

 of the difficult questions here treated, and my most cordial acknowledgements 

 are due to Rear Admiral Rousseau for his great kindness. 



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