Report on Merapi (Indonesia) — 25 March-31 March 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 March-31 March 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, 25 March-31 March 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 reported that beginning at 1056 on 27 March a seven-minute-long eruption at Merapi produced an ash plume that rose 5 km above the crater rim and pyroclastic flows that descended the SSE flank as far as 2 km. The ash plume drifted mainly SW and caused ashfall within 20 km, particularly in areas to the W and including the Mungkid subdistrict and in Banyubiru Village. The report noted that there were no clear precursors for the eruption. Eruptions at 2146 on 27 March and at 0521 the next day generated ash plumes that rose 1 km and 2 km, respectively. Each lasted about 2 minutes and 40 seconds based on the seismic data. Minor ashfall was noted in areas within 5 km, especially to the W, including Krinjing subdistrict. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.
Geologic Background. 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 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive 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 during historical time.