ox THE AFTEK-SHOOK« OP EARTHQUAKES. 113 



()l)servin<r stations, Kuinninoto and Cliinni. may ])ractica1ly be con- 

 sidered as Ijeing- on the respective epi-centres. 



§ 4. OftheooGo after-sliocks recorded at (Jifn durin^u' the first 

 two years, 10 were •• violent." 97 •' strong," 180(S •• weak," and 1041 

 "feeble," while in the remaining 40!) only sounds were heard without 

 shocks. From Tal)les IV and V. it will l)e seen tliat. in the days 

 immediately succeeding the initial great earth(juake, " violent " and 

 •• strong " shocks occurred very often, but that these became rarer as 

 time advanced. Of the 10 " violent " shocks, 9 occurred Avi thin the 

 lirst four months and the remaining 1 in September, 1892, twelve 

 months after. The "strong" shocks occu.rred all within tlie lirst 

 thirteen months, and the '"weak" shocks all within the first twenty 

 months. It thus seems that a.t the earthquake-origin grea.t instabilities 

 are removed quicker than small ones. Again, the numbers oi '"weak ' 

 and '• strong " shocks at Gifu during the first two years are greater 

 respectively than the total numbers recorded during the same time 

 interval at Nagoya and Osaka. Assuming that the after-shocks all 

 originated somewhere near Gifu,^ it may Ije concluded tliat nearly two- 

 thirds of these h-id radii of propagation less than 10 /•/ and that ordy 

 one-fiftieth had radii greater than 35 ri. 



§ 5. The number of after-shocks of the Kumamoto earthcpiake 

 recorded at Kumamoto up to the end of 189o is [)2'2, including 1 

 "violent" shock which happ-ened on August 3rd, 1889, five days 

 after the initia.l e;rrth(piake, 76 '• strong " shocks, and 845 "weak" 

 and "feeble" shocks and sounds. These shocks all extended over 

 small areas, (jnlv the "violent" one reaching a distance greater than 

 20 ri from the origin. 



§ (). In the cases of the Mino-Owari and Kumamoto earth- 

 quakes, all the after-shocks were very much smaller in extent than 



1 See § 33. 



