Report on Kirishimayama (Japan) — 14 January-20 January 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 January-20 January 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Kirishimayama (Japan). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 14 January-20 January 2004. Smithsonian Institution and US Geological Survey.
31.934°N, 130.862°E; summit elev. 1700 m
All times are local (unless otherwise noted)
Seismicity increased from "normal" levels at Kirishima on 13 December, and the same day Dr. Kobayashi of Kagoshima University found new fumarole pits at the volcano's Ohachi Crater. A video camera at the volcano showed steam rising above the crater rim. Observers saw two new pits that formed in the middle of the crater's southern inner wall and steam rising to ~100 m. Also, pebbles (that were 2-3 cm across) and mud were scattered within about 10 m of these pits. JMA issued a volcanic advisory on 16 December, as the possibility of a small eruption had increased, judging from the high level of seismic and thermal activity. On 17 December authorities announced that tourists were not permitted to visit Ohachi Crater. The level of seismicity peaked in mid December, then declined somewhat, continuing at a relatively high level through at least mid January.
Geologic Background. Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located Karakunidake being the highest. Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.