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Report on Merapi (Indonesia) — 16 August-22 August 2023


Merapi

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 16 August-22 August 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, 16 August-22 August 2023. Smithsonian Institution and US Geological Survey.

Weekly Report (16 August-22 August 2023)

Merapi

Indonesia

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 4-10 August and seismicity remained at elevated levels. The SW lava dome produced a total of 244 lava avalanches that descended the SW flank; 34 traveled as far as 1.6 km down the upper part of the Boyong drainage, 207 traveled as far as 2 km down the upper Bebeng drainage, and 3 traveled as far as 1.4 km down the Senowo drainage. Morphological changes to the SW lava dome were due to continuing collapses of material. 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)