Report on Semeru (Indonesia) — May 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 5 (May 1989)
Managing Editor: Lindsay McClelland.
Semeru (Indonesia) Frequent lava avalanches and nuees ardentes
Please cite this report as:
Global Volcanism Program, 1989. Report on Semeru (Indonesia) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198905-263300.
8.108°S, 112.922°E; summit elev. 3657 m
All times are local (unless otherwise noted)
Activity continued in March 1989, with lava flows, avalanches of lava debris, and [pyroclastic flows] that sometimes generated lightning. The number of lava avalanches increased from the previous month, with debris extending 700-1,000 m from the summit. Some associated [pyroclastic flows] reached 1,000-2,000 m from the summit. Thunderous incandescent lava explosions sometimes produced plumes that rose 400-700 m above the summit. During March, seismic stations near Semeru recorded 3,263 explosion earthquakes, 83 avalanche events, 33 strong and five local tectonic shocks, five [pyroclastic flow] signals, and two A-type volcanic events.
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.
Information Contacts: VSI.