76 AKT. 3. — B. KOTÜ : 



clouds were forcibly thrown out, and this act signified the pressing 

 up of Hquid magma from within through the ventholes. The night 

 was rather quiet. 1'liis state of things had continued from the 

 day before. Though <ipp(ircnüy tranquil there occurred really (jreat 

 éruptions during all this time after the Hawaiian pattern, copiously 

 pouring out liquid lava to the surface. 



Velocity Jj^ ^}-^g moming^^ the viscous Stream of lava alreadv 



STREAM reached the flat shore (PI. VI. Fig. 1), a distance of 3 km. 



from t e vent, after three days, crawling at the rate of 3 mP per 



1) The reports of the outbreak at Sakura-jima on January 12th were in the writer's hand 

 in Tokyo late in the evening of the I2th ; the writer thought first that it was an ordinary sort 

 of activity, as we frequently hear of late of Asnma and Kirishima. Early on the next morning 

 some details became known to the writer that the disturbance was of an extraordinary nature. 

 Just a year before the writer had made a trip to southern Kyûshù with a work by I. Fried- 

 laender [loc. cit.) in his hand, and spent a day in Sakura-jima, ^^hen he made some acixuaintance 

 with its geology, w^hich encouraged him to hasten to the scene of activity. 



Leaving Tokyo on the 13th, the writer reached Kagoshima on the 15th at 11 a.m. The 

 writer was the first geologist on the actual scene. The first sight that astonished him was the 

 grand scale of the jjresent volcanic activity, the second was the ' live '-lava actually floAving down 

 the slope near Yokoyama beyond the sea at a distance of 4 Ian. Born in a volcanic land the 

 writer saw the fluent him for the first time in his life. The activities of modern volcanoes in 

 Japan are exclusively of the explosive type, except a few instances of extensive floM's of Myaké-jima 

 in 1874, of Asama in 1783, and lastly, of Unzen in IGSl-'SS (some say 1655-'57) and l791-'92. 



2) The writer measured this on a map (cf. Text-fig. 19.) The estimation was made on the lava 

 flow, '2.0 km. from the main (No. 2) vent and '].hkm. from the third, on a slope of low angles 

 from the shore. Much weight cannot \>e attached to the calci^lation, for the velocity diflEers con- 

 siderably according to the original land form and the distance from vents, due to the degree of 

 cooling and consequently of viscosity. The chemical nature of the magma has also much to do 

 with the velocity. Under the sea the rate must be considerably (jreater than on land. It should 

 be remembered that basaltic lava is of thin fluid and conseqiiently has greater velocity in its 

 forward movement, while the lava of Sakura-jima is of an andesitic (auganitic) magma, and is 

 of a rather viscous nature. Some say, the velocity of the Sakura-jima la-sa-flow to have been 

 45 //(. (!) i)er hour during the 13th and the 14th, and 21 //(. during the 16th and the 18th, and on 

 the 22nd 1 foot an hour. Others calculated the rate of flow to have been 7 m., the average velocity 

 being 7 m. from the 16th to the 24th, or 19 //*. from the 13tli to the 23rd. See posted, p. 85. 



1 or reference, the rate of flows in foreign volcanoes may here be inserted (Wolff, ' Der 

 Vullvanismus,' Bd. I. S. 369). In Vesuvius and Etna it was 3.6-7.2 fc«?. an hour near the vent. 

 In the eruption of Etna in 18G5, it was from 5 to 0.6 /.»»., while further away from the vent it 

 still retained a vekcity of 0.18/t;//i. In the eruption of 1631, the rate of flow was 8 km. per hour ; 

 in 1906 1 km. In 1872, it was 0.433 km ; in 1895, 0.137 km ; averaging from 0.433-0.137 km. In 

 Maima Loa of 1850, it was 30 km. at the beginning, and later 0.276 /<»/(. In Teneriffo, a basaltic 

 lava ran down with a velocity of 19 //(. per hour. Sapi)er says, in the Hawaiian (■rui)tion of 

 1905 it was 10-15 (5-7) m. 



