Report on Gamalama (Indonesia) — October 2007

Bulletin of the Global Volcanism Network, vol. 32, no. 10 (October 2007)
Managing Editor: Richard Wunderman.

Gamalama (Indonesia) Plumes accompany August 2007 increase in seismic activity

Please cite this report as:

Global Volcanism Program, 2007. Report on Gamalama (Indonesia). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 32:10. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN200710-268060.

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Gamalama

Indonesia

0.8°N, 127.33°E; summit elev. 1715 m

All times are local (unless otherwise noted)


On 24 August 2007, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) raised the Alert Level of Gamalama from 1 to 2 (on a scale of 1-4) due to an increase in seismic activity beginning 20 August. Prior to 10 August, diffuse white plumes rose to an altitude of 1.8 km, then increased in altitude to 2 km during 10-23 August. On 23 August, white and gray plumes rose to an altitude of 2.1 km. Concurrent with the increased Alert Level, government officials banned access within a 2-km radius of the active crater. No thermal anomalies were measured by MODIS satellites during this time. CVGHM lowered the Alert Level to 1 on 9 October 2007, based on visual observations of plume altitudes and a decline in seismicity.

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.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/).