172 F. OMORI AND K. HIRAïA : 



probably about 1.2 seconds. The movements, which followed 

 the principal motion, were very small. 



The direction of motion, averaged from the three chief 

 displacements of the second shock given above was S 55° W — 

 N 55° E, pointing very nearly towards the centre of the meizo- 

 seismal area. The greatest motion was in this case directed 

 towards the origin. 



Adopting the mean angle of emergence of 6.7°, which, as 

 it relates to well-defined maximum vibrations, can not but be 

 regarded as real, the depth of the earthquake focus comes out 

 to be 16 km.^ 



12. Eqke. No. 8^. This was a very small shock, whose 

 date is not given, but which was recorded on the same smoked 

 paper as eqke. No. 8. Intensity, very slight. The motion, 

 which consisted entirely of ripples, was chiefly in the (EW) and 

 (V), and was practically zero in the (NS), the maximum range 

 of motion being 0.4 mm. in the (EW), 0.0 mm. in the (NS), and 

 0.1 mm. in the (V). 



13. Eqke. No. 9. The 20th February, 1897 ; 5.49.0 a. m. 

 Intensity, very strong. This earthquake was very extensive in 

 area and caused some damage in the provinces of E-ikuzen and 

 Rikuchu, the origin being situated probably at about 220 km. 

 SE of Miyako. 



The motion was much greater in the (EW) than in the 

 (NS), a considerable amount of the V.M. being also present. 

 The record was, however, imperfect, all the three writing pointers 

 having been thrown out of the record-receiving smoked paper 

 at 18.6 seconds from the beginning. 



1) The depths of earthquake foci have in this paper been calcuhited by the usual 

 method of tlie angle of emergence. 



