Report on Semeru (Indonesia) — 26 June-2 July 2024
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 26 June-2 July 2024
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2024. Report on Semeru (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 26 June-2 July 2024. Smithsonian Institution and US Geological Survey.
Semeru
Indonesia
8.108°S, 112.922°E; summit elev. 3657 m
All times are local (unless otherwise noted)
PVMBG reported that eruptive activity continued at Semeru during 23 June-2 July. Seismicity remained at high levels. Daily white-and-gray ash plumes that were sometimes dense rose 300-1,000 m above the summit and drifted mainly W and SW and occasionally S and SE. Daily eruptive events, sometimes several per day, were recorded by the seismic network, though plumes were not always visually confirmed. Incandescent lava avalanches occasionally descended the Kobokan drainage on the SE flank as far as 1.5 km during 23-30 June. The Alert Level remained at 3 (the third highest level on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km from the summit, and to avoid other drainages 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.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)