Report on Semeru (Indonesia) — 21 May-27 May 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 May-27 May 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Semeru (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 May-27 May 2008. Smithsonian Institution and US Geological Survey.
8.108°S, 112.922°E; summit elev. 3657 m
All times are local (unless otherwise noted)
CVGHM reported that during 15, 17-19, and 21 May, ash plumes rose from Semeru's summit, rockfalls descended the flanks, and multiple pyroclastic flows traveled 500-3000 m from the active crater. On 21 May, incandescent material was propelled from the summit. Based on visual observations and increased seismicity, CVGHM raised the Alert Level from 2 to 3 (on a scale of 1-4). The community was advised not to go within 4 km from the summit on the SE flank.
Geologic Background. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.