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Report on Merapi (Indonesia) — 15 November-21 November 2023


Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 15 November-21 November 2023
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2023. Report on Merapi (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 15 November-21 November 2023. Smithsonian Institution and US Geological Survey.

Weekly Report (15 November-21 November 2023)



7.54°S, 110.446°E; summit elev. 2910 m

All times are local (unless otherwise noted)

BPPTKG reported that the eruption at Merapi (on Java) continued during 10-16 November. The SW lava dome produced a total of 69 lava avalanches that descended the flanks; 10 traveled as far as 1.5 km down the upper part of the Boyong drainage and 59 traveled as far as 1.7 km down the upper Bebeng drainage. Minor morphological changes to the SW lava dome detected in webcam images and during a 16 November drone survey were due to continuing lava effusion and collapses of material. The highest temperature measured at the SW dome during the drone overflight was 292 degrees Celsius, lower than previous measurements. The volume of the SW dome was an estimated 3,348,600 cubic meters and the dome in the main crater was an estimated 2,358,000 cubic meters. Seismicity remained at elevated levels. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit, based on location.

Geological Summary. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)