Report on Gamalama (Indonesia) — 30 November-6 December 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 November-6 December 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Gamalama (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 November-6 December 2011. Smithsonian Institution and US Geological Survey.
0.8°N, 127.33°E; summit elev. 1715 m
All times are local (unless otherwise noted)
CVGHM raised the Alert Level for Gamalama from 2 to 3 (on a scale of 1-4) on 4 December based on seismicity and visual observations during 1-4 December. On 1 and 4 December white plumes rose to an altitude of 0.15 km (492 ft) a.s.l. and drifted W. Clouds obscured views on the other days.
Based on information from CVGHM, the Darwin VAAC reported that during 5-6 December ash plumes from Gamalama rose to altitudes of 2.4-3.0 km (8,000-10,000 ft) a.s.l. and drifted SE.
Geologic Background. Gamalama is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera, and is one of Indonesia's most active volcanoes. The island was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the thorough documentation of Gamalama's historical activity. Three cones, progressively younger to the north, form the summit. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano. Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63.