POPULAR SCIENCE 99 



slopes steeply into one of the deep basins of the Pacific. Crossing 

 this arc almost transversely, there are two great volcanic zones, 

 that of Fuji in the main island of Honshu, which meets the arc 

 near its centre, and that of the island of Kyushu, which diverges 

 from the arc at its southern end. 



It is remarkable how closely the volcanic actions in these 

 two zones are connected. The epoch of most violent eruptions 

 in Japanese history was that of the 14^ years from 1777 to 

 1792, marked by the outbursts of O-shima in 1777, Sakura- 

 jima in 1779, Aogo-shima in 1780, Asama-yama in 1783, and 

 Unsen-dake in 1792. Of these volcanoes, the second and 

 fifth are in Kyushu, the other three in the Fuji zone ; yet, 

 separated as they are by a distance of about five hundred 

 miles, these different volcanoes were thrown, one after another 

 within fifteen years, into great eruption. 



For 130 years, the volcanoes O-shima, Sakura-jima, and 

 Asama-yama have remained almost quiescent, and then again 

 they broke into nearly simultaneous activity. From 1908, and 

 especially from 191 3, the explosions of Asama-yama have been 

 numerous and violent. In 191 2 there were magnificent out- 

 bursts from O-shima. In Kirishima, a volcano not far to the 

 north of Sakura-jima, there were strong explosions on Novem- 

 ber 8 and December 9, 191 3, and January 8, 1914. And these 

 were followed four days later by the great eruption of Sakura- 

 jima. During the six years from 1909 to 19 14, Prof. Omori 

 enumerates 194 eruptions from eleven different volcanoes. In 

 the last year, 1914, as many as seven volcanoes were in action. 

 Previous Eruptions of Sakura-jima. — The record of the 

 Sakura-jima eruptions dates from the year 1468, and from that 

 time until 1914 includes 26 eruptions. Prof. Omori remarks 

 that there are, in these four and a half centuries, three principal 

 epochs of activity. The first extends over the eight years 

 1468 to 1476 and includes five eruptions, of which those of 1471, 

 1475, and 1476 were large outbursts. Then, after the lapse of 

 nearly two centuries, there succeeded a series of eight small 

 eruptions, spread over a century and a quarter (1642 to 1766). 

 These may be regarded as merely preliminary to the second 

 epoch of activity consisting of the great eruption of 1779, 

 which began on November 9 and, after a few days of excessive 

 violence, subsided into a series of minor outbursts lasting 

 during the next ten months. The last nineteen years of the 



