Report on Gamalama (Indonesia) — 12 September-18 September 2012
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 12 September-18 September 2012
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2012. Report on Gamalama (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 12 September-18 September 2012. Smithsonian Institution and US Geological Survey.
0.81°N, 127.3322°E; summit elev. 1714 m
All times are local (unless otherwise noted)
CVGHM reported that during 1-14 September cloudy weather and fog at Gamalama mostly prevented observations from the post in Marikurubu and from S Ternate (S, SE, and E part of island); white plumes were sometimes observed rising 10 m above the crater. A phreatic eruption on 15 September at 2027 produced ashfall in Ternate. An eruption at 1415 the next day was accompanied by rumbling sounds. A plume rose 1 km and drifted SE and S, producing ashfall at the Gamalama observation post five minutes later. Neither eruption was observed due to fog. The Alert Level was raised to 3 (on a scale of 1-4) on 16 September. Visitors and residents were warned not to approach the crater within a radius of 2.5 km.
Geological Summary. 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 extensive documentation of 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; the S-flank Ngade maar formed after about 14,500–13,000 cal. BP (Faral et al., 2022). 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.