The impact craters from the eruption of Bandai volcano in AD1888, Northeast Japan

Abstract

Bandai volcano consists of three peaks of the Bandaisan, Kushigamine and Akahaniyama. On July 15^<th> 1888, a phreatic eruption occurred on the north side of the Bandai volcano. After this eruption, Kobandaisan collapsed. The debris flow went down mostly in the north-eastward direction, however some traveled down on the south-eastward side. In 1985, Chiba discovered concave geographical features in the Kagami-numa, the top of the Bandai volcano. Chiba did field investigations, and created a map detailing position, and created a cross section. From the following points, I reached the conclusion that the concave geographical features of Kagami-numa were impact craters which formed by an eruption of 1888. (1) Some theses at 1888 eruption of Bandai volcano discuss the cinder falls and the resultant impact craters. (2) A perpendicular section of these concave geographical features of the Kagami-numa has the shape of a reverse cone and opens in the direction of the explosion in 1888. (3) The features of the sand boil isn't seen in these concave geographical features in the Kagami-numa. (4) The previous eruption occurred 1200 years before the one in 1888. It is very unlikely that the impact craters of an eruption that occurred 1200 years before still exist. (5) Stones are distributed over the marsh bottom, but stones are not found in these concave geographical features, suggesting that these concave geographical features are new. The impact craters from the eruption of 1888 also exists on Numanotaira and Akahani-yama.