Report on Ibu (Indonesia) — March 2005
Bulletin of the Global Volcanism Network, vol. 30, no. 3 (March 2005)
Managing Editor: Richard Wunderman.
Ibu (Indonesia) Periodic ash emissions during June-August 2004 and inferred dome growth
Please cite this report as:
Global Volcanism Program, 2005. Report on Ibu (Indonesia). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 30:3. Smithsonian Institution. https://dx.doi.org/10.5479/si.GVP.BGVN200503-268030.
1.488°N, 127.63°E; summit elev. 1325 m
All times are local (unless otherwise noted)
The Directorate of Volcanology and Geological Hazard Mitigation (DVGHM) released ten nearly identical weekly reports on Ibu during 31 May-29 August 2004. They noted that Ibu emitted "white ash" (steam plumes) reaching ~ 50-150 m above the crater rim. Continued growth of the intracrater lava dome was either recognized or assumed. Ibu lacked a working seismic instrument. Its hazard status remained at Level II (Yellow, a condition meaning 'caution or on guard' ('waspada' in Indonesian).
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: Directorate of Volcanology and Geological Hazard Mitigation (DVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).