INTERESTING PHENOMENA ON THE ERUPTION OF USU 277 



toward the south, the amount being greatest on the northwest side 

 of the mountain. In the Kompirayama region the ashes that fell 

 formed a layer up to 8 and 10 cm. in thickness, while at the distance 

 of 1 km. from the mountain thicknesses of 3 mm. to 1 cm. were found. 

 On the north side of the second group of cones, a general thickness 

 of 1 cm. was found, while at their very foot the layer was 30 cm. 

 in thickness. But on the east side and south side of the mountain 



Fig. 20. — Bombs and mud-flow from crater No. XLII. Taken July 31, 19 10 



very little ash was found. Besides the ash, sand, and bombs, from 

 five of the craters mud and hot water were ejected. Among these 

 rive craters No. VIII was the first to erupt (Fig. 17), while No. XIII 

 ejected the largest quantity of mud (Fig. n). From the craters 

 to the lake is an expanse of mud which flowed out to a width of 

 200 m., a length of 500 m., and a thickness of 1 . 5 m. In addition 

 to this great quantity of mud on the land there was a large amount 

 that flowed into the lake. The mud is composed of fine, gray- 

 colored plagioclase, hypersthene, augite, and magnetite, with a 



