NOTES OX .TAPAXESE EAKTIIQITAKES. 409 



IV. Distribution of Destructive Earthquakes in Historic 

 Times of Japan.' 



0, The distribution in time of tlie destruclive earthquakes in 

 Japan^ IVom the 8th centuiy to tlie present lime is graphically 

 sliown in fig. 5, from -which it will 1)0 observed that the disti'i- 

 bution was not uniform, but was rather in groups. 



10. The epochs of the nrinimum frequency of destructive 

 earthquakes selected from the epoch of the Tokugawa Shogunate, 

 which dates from the beginning of the 17th century, -were as 

 follows : — in the interval of 31 years between the earthquake at 

 Ko-ori (in Iwashiro) of the 7th Octol)er, 1731, and the earthquake 

 in Sado of the 31st October, 1762, there was only the earthquake 

 at Takata (in Echigo) of the 20th ^lay, 17r)l ; and in the inter- 

 val of 31 years and 3 months between the Shinano earthquake 

 of the 23rd April, LS-IH, and the Kumamoto earthquake of the 

 28th July 1880, there was only the earthquake in Iwami of the 

 14th March, 1872. 



11. On the other hand, the most remarkable cpoclis of maxi- 

 mum frequency of destructive earthquakes were as follows : in the 

 interval of '"> years and ~) months between Älarch, 1044, and the 

 3rd August, 1641), there were nine destructive earthquakes, 

 giving as average one in every 8 months ; in the interval of 11 

 years and "> months between the 21st April, 1 O-IO, and the 28th 

 September, 1670, there were twelve destructive earthquakes, 

 o-ivino' as average one in 122 months ; in the interval of ö vears 

 and 1 month between the 11th March, 1803, and the 23rd Apiil, 

 1858, there w^ere eight destructive earthquakes, which give one 

 to every 9 months ; and, finally, in the interval of 9 years, bet- 



1) Formosa, Liu-kin Islands and Hokkaido excepted. 



