Report on Ibu (Indonesia) — 27 October-2 November 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
27 October-2 November 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Ibu (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 27 October-2 November 2021. Smithsonian Institution and US Geological Survey.
1.488°N, 127.63°E; summit elev. 1325 m
All times are local (unless otherwise noted)
PVMBG reported that during 26 October-2 November gray-and-white ash plumes from Ibu rose 200-800 m above the summit and drifted N, W, and S. There were at least 151 eruptive events observed during 28-30 October. The Alert Level remained at a 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side.
Geological Summary. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, has contained several small crater lakes. The 1.2-km-wide outer crater is breached on the N, creating a steep-walled valley. A large cone grew ENE of the summit, and a smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. The first observed and recorded eruption was a small explosion from the summit crater in 1911. Eruptive activity began again in December 1998, producing a lava dome that eventually covered much of the floor of the inner summit crater along with ongoing explosive ash emissions.