Report on Ibu (Indonesia) — 20 March-26 March 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 March-26 March 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on Ibu (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 20 March-26 March 2019. Smithsonian Institution and US Geological Survey.
1.488°N, 127.63°E; summit elev. 1325 m
All times are local (unless otherwise noted)
The Darwin VAAC reported that a minor ash plume from Ibu rose to an altitude of 2.4 km (8,000 ft) a.s.l., drifted about 17 km NE, and dissipated. An ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. later that day, and to 2.4 km on 23 March; both plumes drifted E. The Alert Level remained at 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.
Geologic Background. 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, contained several small crater lakes through much of historical time. The outer crater, 1.2 km wide, is breached on the north side, creating a steep-walled valley. A large parasitic cone is located ENE of the summit. 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. Only a few eruptions have been recorded in historical time, the first a small explosive eruption from the summit crater in 1911. An eruption producing a lava dome that eventually covered much of the floor of the inner summit crater began in December 1998.