Report on Merapi (Indonesia) — 2 December-8 December 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
2 December-8 December 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Merapi (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 2 December-8 December 2020. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
BPPTKG and PVMBG reported that during 27 November-8 December white emissions from Merapi rose as high as 600 m above the summit. Rock avalanches were heard, though not visually confirmed due to weather conditions. A comparison of photos taken on 26 and 29 November showed no morphology changes in the summit area. Seismicity was higher than the previous week. Electronic Distance Measurement (EDM) data continued to measure a distance shortening between points in the NW at a rate of 11 cm per day. The Alert Level remained at 3 (on a scale of 1-4).
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.