Report on Gamalama (Indonesia) — 4 November-10 November 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 November-10 November 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Gamalama (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 4 November-10 November 2015. Smithsonian Institution and US Geological Survey.
0.8°N, 127.33°E; summit elev. 1715 m
All times are local (unless otherwise noted)
PVMBG reported that during 1 August-4 November seismicity at Gamalama fluctuated, and was dominated by hybrid earthquakes and signals indicating emissions. Three periods of increased seismicity were recorded during 3-5 and 11-19 August, and 8-22 October, though seismicity declined overall.
A sudden, small eruption from a fissure on the NW flank occurred at 1953 on 8 September with no precursory seismicity, and produced a plume that rose 1 km. Gray plumes rose from 300-600 m the vent during 9-24 September. White plumes rose from Main Crater and fissures on the E and NW flanks as high as 200 m during 1 October-3 November. The Alert Level remained at 2 (on a scale of 1-4); visitors and residents were warned not to approach the crater within a 1.5-km radius.
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.