Report on Ibu (Indonesia) — January 1999
Bulletin of the Global Volcanism Network, vol. 24, no. 1 (January 1999)
Managing Editor: Richard Wunderman.
Ibu (Indonesia) First eruption since 1911 is being monitored
Please cite this report as:
Global Volcanism Program, 1999. Report on Ibu (Indonesia). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 24:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199901-268030.
1.488°N, 127.63°E; summit elev. 1325 m
All times are local (unless otherwise noted)
Ibu volcano on Halmahera island started erupting on 31 December 1998. A plume rose to 1,000 m above the summit as a result of mild explosions. On 2 January, personnel from the Volcanological Survey of Indonesia (VSI) who went to the island to take COSPEC measurements observed an eruption. Ashes were deposited to ~3 mm depth in surrounding villages. On 5 January another eruption lasted for 60 minutes. Local people reported that a lava flow reached the lower lip of the crater on 16 January.
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.
Information Contacts: R. Sukhyar and Dali Ahmad Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No.57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).