174 F. OMORI AND K. HIKATA : 



The duration of the H. M. was 42 seconds, and that of 

 the V.M. was 33 seconds. 



The preliminary tremor, whose duration was 2.6 seconds, 

 consisted of ripples of an average period of 0.080 second in the 

 (EW), 0.073 second in the (NS), and 0.065 second in the (V). 

 (For the diagram, See fig. 3). 



The principal portion, wliich lasted for about 0.7 second, 

 consisted of vibrations of an average period of 0.12 second in 

 the (EW), 0.12 second in the (NS), and 0.13 second in the 

 (V). The first prominent displacement and the two succeding 

 ones were as follows : — 



(First motion). 0.8 mm. towards W, 0.62 mm. towards S, 0.2 mm. 



upwards. Kesiiltant 2a = 1.0 mm., direction W 43° S, the angle 



of emergence ■■= 12°. 

 (Second motion). 1.2 mm. towards E, 1.0 mm. towards N, 0.2 mm. 



downwards. Kesultant 2a = 1.6mm., direction NE, the angle of 



emergence = 7.°2. 

 (Third motion). 1.2 mm. towards W, 1.0 mm. towards S, 0.2 mm. 



upwards. Eesultant 2« = 1.6 mm., du-ection SW, the angle of 



emergence = 7.°2. 



The mean direction of motion deduced from the above three 

 displacements is NE — SW, while the corresponding angle of 

 emergence = 9°. The depth of the earthquake focus comes out 

 to be 10 km. 



The end portion of the earthquake consisted of ripples, 

 whose average period was a little shorter than that in the prin- 

 cipal portion. Thus, measuring from about 3.3 seconds after the 

 beginning, when the principal portion ceased, the average period 

 was 0.078 second in the (EW), 0.078 second in the (NS), and 

 0.067 second in the (V). Again, measuring from 7.8 seconds 



