Report on Semeru (Indonesia) — 14 December-20 December 2022
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 14 December-20 December 2022
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2022. Report on Semeru (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 14 December-20 December 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 16-20 December. At 0455 on 16 December an eruptive event produced a dense white, gray, and brown plume that rose 1 km above the summit and drifted N. At 0500 on 18 December a dense gray ash plume rose 300 m and drifted N and NE. At 0623 and 0755 that same day dense white-and-gray ash plumes rose 1 km and 700 m, respectively, and drifted N. At 0516 and 0703 on 19 December white-and-gray ash plumes rose 400-700 m and drifted N and NE. At 1558 a dense gray-to-brown ash plume rose 1.5 km and drifted N and NE. At 0545 on 20 December an ash plume rose 600 m and drifted N. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 5 km away from the summit, and 500 m from Kobokan drainages within 17 km of the summit, along with other drainages originating on Semeru, including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.
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.