Report on Ibu (Indonesia) — 9 April-15 April 2008

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 April-15 April 2008
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2008. Report on Ibu (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 April-15 April 2008. Smithsonian Institution and US Geological Survey.

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1.488°N, 127.63°E; summit elev. 1325 m

All times are local (unless otherwise noted)

CVGHM reported that white plumes from Ibu rose to an altitude of 1.5 km (5,000 ft) a.s.l. during 17-31 March and were spotted "often." The plume altitudes increased to 1.6 km (5,200 ft) a.s.l. on 31 March. During 4-5 April, seismicity increased in amplitude and plume altitude increased to 1.8-2.0 km (5,900-6,600 ft) a.s.l. On 5 April, the eruption plume was gray and material fell onto the crater. The Alert Level remained at 2 (on a scale of 1-4). The community was not permitted to climb or approach the crater.

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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)