Report on Ibu (Indonesia) — 5 June-11 June 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 June-11 June 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Ibu (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 June-11 June 2013. Smithsonian Institution and US Geological Survey.
1.488°N, 127.63°E; summit elev. 1325 m
All times are local (unless otherwise noted)
CVGHM reported that during May through 6 June white-to-gray plumes rose 200-450 m above Ibu's crater rim. Seismicity increased and volcanic tremor was detected. The lava dome contained to grow, especially the N part, and in early June had grown taller than the N crater rim. Based on visual and instrumental observations, as well as the hazard potential, CVGHM increased the Alert Level to 3 (on a scale of 1-4) on 7 June. The public was warned to stay at least 3 km away from the active 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.