Report on Kirishimayama (Japan) — 9 December-15 December 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 December-15 December 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Kirishimayama (Japan). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 December-15 December 2020. Smithsonian Institution and US Geological Survey.
31.934°N, 130.862°E; summit elev. 1700 m
All times are local (unless otherwise noted)
JMA noted that no eruption had occurred at Shinmoedake (Shinmoe peak, a stratovolcano of the Kirishimayama volcano group) since 28 June 2018. Volcanic earthquakes with hypocenters just below Shinmoedake had increased around 17 November 2019, fluctuated afterwards, and then began a decreasing trend in mid-October 2020. Sulfur dioxide levels were generally low, deformation data showed no changes, and both fumarolic and geothermal area activity remained stable. The Alert Level was lowered to 1 (on a scale of 1-5) on 11 December.
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.