168 F. OMORI AND K. HIRATA I 



The duration of the H.M., as well as that of the V.M. was 

 100 second. 



In the preliminary tremor, whose duration was 5.2 seconds, 

 the amplitude of motion was much greater in the (EW) and the 

 (V) than in the (NS), the maximum ranges being 5.4 mm. in 

 the (EW), 1.4 mm. in the (NS), and 3.5 mm. in the (V). 



At about 4 seconds from the beginning, there were two 

 vibrations of the period of 0.8 second each, which consisted of 

 the following four displacements: 



{(First motion) : 2.6 mm. towards W, 2.1 mm. downwards. 

 Resultant 2rt = 3..3 mm., the angle of emergence = 39°. 



{(Second motion) : 1.7 mm. towards E, 3. .5 mm. upwards. 

 Resultant 2a = 3. 9 mm., the angle of emergence = G4°. 



{(Third motion): 2.8mm. towards W, 3.4mm. downwards. 

 Resultant 2« = 4.4 mm., the angle of emergence = .50°. 



{(Fourth motion) : 42 mm. towards E, 2,8 mm. upwards. 

 Resultant 2« = ,5.1 mm., the angle of emergence = 34°. 



It is to be remarked that the above four angles of emer- 

 gence relate to the vibrations in the preliminary tremor, and 

 are probably very different fiom those in the principal portion 

 of the shock, the mean angle of emergence of 47° giving obvi- 

 ously a too great depth of the earthquake focus. 



The principal portion, whose duration was 26 seconds, was 

 unfortunately vitiated by the large oscillations of the seismograph 

 pendulums. The elements of the ripples have, however, been 

 measured and found to be as follows : — 



(EW) (NS) (V) 



maximum 2« >3.4mm. 3.4 mm. (obscure) 



average period 0.088 second 0,08.5 second 0,0 G4 second. 



