Bandai volcano (Bandai-san), one of Japan's most known active volcanoes, is an complex andesitic stratovolcano rising above the north shore of Lake Inawashiro. The volcano is located in the southern part of the NE Honshu volcanic arc. The last magma was erupted at Bandai about 25,000 years ago, but during the past 5000 years, 4 major phreatic explosions have occurred at the volcano. 2 of them occurred in historical time, in 806 and 1888. In 1888, the youngest edifice of Bandai, Ko-Bandai, collapsed in a catastrophic way after a large phreatic eruption, producing a debris avalanche that buried several villages and formed several large lakes. Seen from the south, Bandai presents a conical profile, but much of the north side of the volcano is missing as a result of the collapse of Ko-Bandai volcano during the 1888 eruption.

The Bandai complex is formed of several overlapping andesitic stratovolcanoes, the largest of which is O-Bandai. Ko-Bandai volcano, which collapsed in 1888, was formed about 50,000 years ago.

O-Bandai volcano was constructed within a horseshoe-shaped caldera that formed about 40,000 years when an older volcano collapsed, forming the Okinajima debris avalanche, which traveled to the SW and was accompanied by a plinian explosive eruption.

(Source: GVP)

Bandai-type eruptions:

The 1888 phreatic eruption and slope failure event is often referred to as Bandai-type (Bandaian) eruptions: major slope failures caused by phreatic eruptions. In contrast, Bezymianny-type eruptions (after the 1956 collapse of Bezymianny volcano in Kamchatka), include a magmatic component, i.e. juvenile magma erupted. Slope failure without eruption can occur as well, as happened at Unzen volcano in 1792.