Report on Gamalama (Indonesia) — 30 July-5 August 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 July-5 August 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Gamalama (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 30 July-5 August 2003. Smithsonian Institution and US Geological Survey.
0.8°N, 127.33°E; summit elev. 1715 m
All times are local (unless otherwise noted)
VSI raised the Alert Level at Gamalama to 3 (on a scale of 1-4) after an explosion on 31 July around 1430 produced an ash column that rose 0.5-1 km above the volcano and drifted E. Another explosion occurred at 1439 that rose to 1-1.5 km above the volcano, and deposited ash in the town of Ternate ~30 km N of the volcano. The next large explosion occurred at 1625 and ejected incandescent material, produced an ash column that reached 1-2 km above the summit and drifted E, and was accompanied by a pyroclastic flow that traveled ~1 km into the Togorara Valley. VSI raised the Alert Level to 4, the highest level, and some residents near the volcano were evacuated. After an explosion at 1704 produced an ash cloud to 1-1.5 km above the volcano, low-level ash and gas emissions occurred at Gamalama through 1 August.
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.