i8 9 5 THE AFTER-SHOCKS OF EARTHQUAKES. 



395 



have so far recovered its former stability that there will be no more 

 than one slight shock a month. By this time the total number of 

 after-shocks recorded at Gifu will probably not fall short of four 

 thousand. Before 1891, the average yearly number of shocks at the 

 same place was about fifteen. 



Another point of some importance is the connexion between the 

 intensity of the shocks and their time of occurrence. Of the ten 

 violent shocks recorded at Gifu, nine occurred within the first four 

 months, and the last in September, 1892. All of the strong shocks 

 took place within the first thirteen months, and all the weak ones but 



A 



Nov 



Jan 



Jan 



4Sqi 



Fig. 3. Curve showing Diminution of After-Shocks in time. 



four within the first twenty months. During the few days immediately 

 succeeding the earthquake, feeble shocks and sounds were compara- 

 tively rare, and it was only after the lapse of several weeks that they 

 came into prominence. Towards the close of the year 1893, with the 

 four exceptions just alluded to, feeble shocks and sounds alone were 

 recorded. 



The remaining earthquakes discussed by Mr. Omori were less 

 intense, and the number of after-shocks was, in each case, much 

 smaller. They yield, however, somewhat similar results. 



The Kumamoto earthquake occurred on July 28, 1889, at 



2 F 2 



