262 



S. Powers — Volcanic Domes in the Pacific. 



of Volcano Bay and 8 miles from the sea. During the last 

 period of activity, in L909, a volcanic- dome rose in the summit 

 crater to a heighl of about 400 feet. The dome (fig. 1) is 

 now n sleep-sided mass of blocks with a flat top from which 



steam issues. 



Smoke was first seen on the summit of the mountain Jan- 

 uary 11, 1909, and ash fell on the 22nd and 27th of that 

 month. 3 During February smoke and ash were reported on 



Fig. 1. 



Fig. 1. The volcanic spine which rose in the summit crater of Tarumai in 

 1909 (after Oinouye). 



four occasions ; on March 3 a noise was heard and on March 

 14 there was an earthquake, caused apparently by a gas explo- 

 sion. During this period the new lava was rising in the vent, 

 for on March 30 an explosion was accompanied by a heavy 

 fall of ash to the southeast and bomhs of new material were 

 ejected. The mountain was ascended on April 4, but no fresh 

 lava had yet appeared in the crater. On April 12 an explosion 

 threw out ash, lapilli, and anorthite crystals from the new lava 

 which was evidently just beneath the floor of the crater. 



Fire was first seen on April 17, indicating that, the new 

 lava had reached the surface. A dome commenced to grow and 

 it was seen over the rim of the crater on the 20th. Three days 

 later an ascent of the mountain was made and a glowing, 

 rounded dome was seen. A maximum height of 440 feet was 

 reached about May 1, but a considerable settling of the center 

 of the mass followed the rapid rise, forming a flat top and 



3 The outbreak is described by: II. Simotomaij Der Tarumaiausbruch in 

 Japan 1909, Zeitschrift Ges. Erdkunde, Berlin, 1912, pp. 433-444; I. 

 Friedlaender, TJeber einige japanisehe Vulkane, Mitt. Ges. Natur- und 

 Volkerkunde Ostasiens, vol. xii, Tokyo, 1909. 



