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Report on Merapi (Indonesia) — 30 March-5 April 2022


Merapi

Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
30 March-5 April 2022
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2022. Report on Merapi (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 March-5 April 2022. Smithsonian Institution and US Geological Survey.

Weekly Report (30 March-5 April 2022)

Merapi

Indonesia

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

All times are local (unless otherwise noted)


BPPTKG reported no significant morphological changes at Merapi’s summit lava dome during 25-31 March, though the height of the dome below the SW rim had increased by 4 m. Based on photo analyses, the volume of the SW lava dome had a volume of 1.7 million cubic meters while the central lava dome was 2.6 million cubic meters. Seismicity remained at high levels. As many as 118 lava avalanches originating from the SW dome traveled a maximum of 2.5 km down the Bebeng drainage on the SW flank. On 28 March two pyroclastic flows were recorded on a seismogram that descended 2.5 km SW, one of which occurred at 1509. On 1 April a pyroclastic flow at 1500 descended 1.5 km down the SW flank. Based webcam, satellite, and wind data, the Darwin VAAC reported re-suspended ash that rose to 100 m (300 ft) a.s.l. As many as 37 avalanches were detected, but the distance and direction were not observed. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-5 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.

Sources: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Darwin Volcanic Ash Advisory Centre (VAAC)