Report on Merapi (Indonesia) — 17 May-23 May 2023
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 17 May-23 May 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, 17 May-23 May 2023. Smithsonian Institution and US Geological Survey.
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 12-18 May and seismicity remained at elevated levels. The SW lava dome produced 182 minor lava avalanches that traveled as far as 1.8 km down the SW flank (upstream in the Bebeng and Boyong drainages) and one that traveled 500 m NW (upstream of the Senowo River). Morphological changes to the SW lava dome due to continuing collapses of material were evident in webcam and drone images. 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.