JOURNAL OF THE COLLEGE OF SOTENOE, IMPERIAL UNIVERSITY, 

 TOKYO, JAPAN. 



VOL. XXI., ARTICLE 1. 



Frequency of After-Shocks 



and 



Space-Distribution of Seismic Waves.'^ 



By 

 S. Kusakabe, Rigahishi. 



With one plate. 



Contents. 

 I. Introduction. 

 II. Experimental researches. 



III, Frequency o? after-shocks. — Transference of the centre of after- 



shocks. 



IV. Iso-frequency curves ïor after-shocks. 



V. Seismic frequency and degree of damage in a given region. — 

 Sympathetic shocks. 



Introduction. 



As to the frequency of after-shocks, a hyperbolic formula 

 was empirically obtained by Prof. F. (Jmori'^ about ten years ago. 

 That his formula gives satisfactory results was adequately shown 

 by him in his valuable paper *' On the after-shocks of earth- 



1) An abstract of this paper may be found in lie Proceedings of the Tokyo Physico- 

 Mathematical Society, Vol. II. ^'o. 11. May, 19)4. Tlie Pub. of the E. I. C. in K. L. No. 

 17, 1904. 



2) F. Ômori, This journal, Vol. VII. 



