THE (iRKAT ERUPTION OF SAKURA-.TIMA IN 1914. 105 



party by Colonel Kanéko, of the Hydrographie Office of the Im- 

 perial Japanese Navy. 

 ,,. The lava-front of the western lava-field (Text-fijj;. 



LAVA-FIEI.D j,)^ ^ -^^^ ^^^^^ ^^^^^.^ ^^^ j,^^^^^ ^^^^^ .^^Q^^. 24 4 



fathoms deep in average, which is eqnal to 44.6 m. As the bottom 

 was gradually and uniformly slanting the mean depth would have 

 been 22.3 m. Since the islet of Karasii-jima (22 m. high), located 

 at the middle of the marine lava-field on the 10 -fathom-line 

 (18.3 m.), was now completely buried (January 19th) under lava, 

 the thickness of the lava -sheet at this point must be not less than 

 40 m. The thickness of flow on land is also about 40 m. There- 

 fore the average thickness of the entire western lava -field will be 

 approximately 50 m}^ The writer is on this point in perfect accord 

 with all his colleagues mentioned in the Table (p. 107). The field 

 is 4 km. in axial direction and 2 hn. in breadth at the front. 



A little more basic lava crawled down for a dis- 

 tance of 4 hn. and spread in the same measure over 

 the eastern slope, then finally plunged into the sea and choked up 

 the narrow strait of Séto, 30 to 40 fathoms deep. The lava of this 

 area makes a flat of 120 m. upon the buried slope originally 80???. 

 in altitude, and a hill top on shore, 103 7?2. high (Akashi Gongen, 

 PI. VIII. Figs. 2-3 ; PI. IX. Figs. 2-3), was overflowed with a sheet 

 of lava-flow. The thickness of lava on land may therefore 

 be rekond at 40 m., as in the flow on the opposite side. The 

 contiguous lava-field in the sea has, however, a thickness of 

 100 m. 



Eastern 

 Lava-field 



1) From experience the writer is disposed to think that the average thickness of a single 

 lava-flow of a femic andesitic magma on land amounts to from thirty to fifty metres, as we can 

 often measure it at the lava-front, as well as in the benches within the steep crater-wall of the 

 Japanese volcanoes. The limitation of the thickness mainly depends upon the viscosity in- 

 herent in the chemical nature of the modern Japanese lavas. 



