262 



Y. OINOUYE 



The report of the Municipal Office and the members of the Meteoro- 

 logical Observatory of Sapporo and Hakodate give the numbers in 

 Table I. 



TABLE I 



Number of Earthquakes Observed at Nishimombetsu 



Date 



Violent 



Strong 



Weak 



Tremor 



Total 



July 



August 



22. 



23- 

 24. 



25- 



26. 

 27. 

 28. 

 29. 

 3°- 

 3i- 



28 

 19 



13 



48 



134 

 58 

 11 



14 

 3 



* Lack of observation for three hours. The number is estimated by means of an average for the 

 three preceding and the three following hours. 



From hourly observations the following results were obtained. 



From July 22, 7:00 a.m., to July 23, 7:00P.M., 36 hrs., 66 quakes, i.Sperhr. 

 From July 23, 7:00P.M., to July 25, 8:00 a.m., 37 hrs., 533 quakes, 14.4 per hr. 

 From July 25, 8: 00 a.m., to July 25, 10:00 p.m., 14 hrs., 48 quakes, 3.4perhr. 



The writer's visit to Mount Usu was made on the afternoon 

 of July 24, amid the climax of the quaking. At that time the quakes 

 occurred rather oftener than once in five minutes. The houses 

 trembled so from the subterranean violence that the windows 

 rattled continually throughout the entire day, and made so much 

 noise that no one could stay within the houses. It was noticed 

 that every quake was preceded by the sound which seemed to 

 come from deep within the earth, or as if heavy artillery were being 

 fired in the distance. But sometimes on the east side of the moun- 

 tain, or in the direction of Volcano Bay, probably owing to the 

 echoes, the same sound was heard. It frequently happened that 

 the sound was first heard in the distance; then a landslide was 

 seen on the dome of O-usu; and following almost immediately 

 the quivering of the earth was felt. A year previous, when the 

 writer visited Usu, a small column of steam was seen to rise from 

 the small pit on the west side of O-usu, and this was the same in 



