Report on Semeru (Indonesia) — 5 January-11 January 2022
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
5 January-11 January 2022
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2022. Report on Semeru (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 January-11 January 2022. Smithsonian Institution and US Geological Survey.
8.108°S, 112.922°E; summit elev. 3657 m
All times are local (unless otherwise noted)
PVMBG reported that the eruption at Semeru continued during 5-11 January. Crater incandescence was visible each night. Gray-and-white plumes rose 300-600 m during 4-8 and 10 January. Pyroclastic flows descended the Kobokan (SE) and Lengkong drainages during 5-6 January and avalanches traveled 700 m down the Kobokan drainage during 6-7 January. At 2311 on 7 January a pyroclastic flow traveled 3 km down the Kobokan drainage, and another traveled 1 km down the same drainage during 8-9 January. The Alert Level remained at 3 (on a scale of 1-4). Due to lahar, avalanche, and pyroclastic flow hazards, the public was warned to stay at least 500 m away from the Kobokan drainage within 17 km of the summit, and other drainages originating on Semeru including the Bang, Kembar, and Sat.
Geological Summary. 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.