POPULAR SCIENCE 105 



considerable strength and duration, and was registered as a 

 great earthquake in European observatories. In Kagoshima, 

 walls were overthrown and nineteen persons killed. It is 

 evident, as Prof. Omori remarks, that the earthquake must 

 have originated at a great depth, and must have been caused by- 

 stresses acting along the whole volcanic chain in southern 

 Kyushu, rather than by the local operations within Sakura-jima. 



About one or one and a half hours after the earthquake, a 

 small seismic sea-wave or tsunami swept over the low-lying 

 portion of Kagoshima. It was at first supposed to be a result 

 of the earthquake, but the time-interval between the shock and 

 the arrival of the sea-wave would imply too great a distance 

 for the origin of the earthquake. The day, moreover, was that 

 of full moon, and the tide was high at the time, the level of the 

 water in Kagoshima harbour being only about half a yard 

 below the top of the quay wall. There can be little doubt that 

 Prof. Omori is correct in assigning the origin of the sea-wave 

 to a sudden small depression in the bed of Kagoshima Bay. 



Besides the great earthquake, numerous tremors accom- 

 panied the eruption. Prof. Omori registered these small 

 movements from January 16 onwards by means of a tremor- 

 recorder magnifying about 200 times. He distinguishes two 

 kinds of eruptions according as they were, or were not, accom- 

 panied by loud detonations. The former were represented by 

 small seismic movements with a total range of about -^ of an 

 inch, the latter by larger movements with about ten times that 

 range. In his opinion, the loud detonations are produced by 

 the sudden rupturing of the partially solidified lava-bottoms of 

 the craterlets and, though alarming, are merely connected with 

 superficial actions ; while the other eruptions are more im- 

 portant phenomena and consist in powerful projections of 

 ashes and gases along pre-existing and deeply-seated channels. 



Relations between the Eruptions of the South Kyushu Volcanic 

 Chain. — The eruption of Sakura-jima occurred in close connec- 

 tion with other outbursts in the volcanic chain of South Kyushu. 

 It is worthy of notice that these outbursts occurred in succes- 

 sion from north to south, and all within the first quarter of 19 14. 

 Thus, on January 8 there was a strong explosion from Kiri- 

 shima (fig. 1) ; on January 12, the great eruption of Sakura- 

 jima ; on February 13, the Iwo-jima was in eruption and this 

 outburst was accompanied by a strong earthquake closely 



