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Report on Semeru (Indonesia) — 12 March-18 March 2003

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 March-18 March 2003
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2003. Report on Semeru (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 12 March-18 March 2003. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (12 March-18 March 2003)



8.108°S, 112.922°E; summit elev. 3657 m

All times are local (unless otherwise noted)

During 3-9 March, volcanism at Semeru remained at high levels. "White-gray ash plume[s]" rose to low levels above the summit and several "pyroclastic avalanches" traveled 200-2,000 m into Besuk Kembar River. Seismicity was dominated by 794 explosion earthquakes. The Alert Level at Semeru remained at 2 (on a scale of 1-4).

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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)