140 F. OMORi : 



21. The earthquake of the 26th ]\Iay, 1898. 



This earthquake origmated in the province of Echigo, near 

 tiie town of Tokaniachi, about 140 km. N\V of Tokyo. In tlie 

 nit^izoseismal area, the shock caused much damage to buildings, 

 aUhough it kn^elled none to the ground. In Tokyo the motion 

 was strong enough to cause people to run out of doors. 



The diagram obtained from the two component Horizontal 

 Pendulums are reproduced in fig. 17 and fig. 18. The earthquake 

 began at 8.0.0 a,.m., and after 17 seconds the motion became 

 large, till at *J0 seconds from the commencement, the EW compo- 

 nent pointer went off the record-receiver. The motion in tiie 

 N8 component, which was not so large as in the other component, 

 was successfully recorded to the end. The total duration, not- 

 withstanding the violence of motion, was short, amounting to 

 only about 30 minutes. 



The NS component. The motion began with long-period 

 vibrations, of which there were 8 well-defined ones with an average 

 period of 10.4 seconds. The range of motion of one of tlie most 

 prominent of these vibrations was 5.(i mm., its period being 10.8 

 seconds. Then followed a great number of well-defined vibrations, 

 whose period, averaged from the first oO vibrations, was 4.0 

 seconds. The two maximum movements belonging to this group, 

 which occurred respectively at 62 and 96 seconds from the com- 

 mencement were the following : — 



[range of motion 11.7 mm., period 4.8 seconds ; 

 [range of motion 11.7 mm., period 4.2 seconds. 



This epoch of the most active motion was followed by a 

 short interval- of time, during which the motion was small 

 and superposed by ripples. Then followed again rather, well- 

 defined waves of a slightly longer period, interrupted " sometimes 



