Report on Merapi (Indonesia) — 26 October-1 November 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 October-1 November 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Merapi (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 26 October-1 November 2016. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
BNPB reported that a lahar induced by moderate to heavy rain swept nine sand mining trucks down the Bebeng River on Merapi's SW flank; at least one truck was buried and six were severely damaged. There were no fatalities as the miners and other people at the scene escaped. Material at the summit and on the flanks produced during the October-November 2010 eruption was an estimated 20-25 million cubic meters, contributing to the continuing high potential of lahars during heavy rain. BNPB recommended that the public remain vigilant during rainy weather because a lahar formed on the upper flanks of Merapi can reach the bottom in less than 30 minutes. The Alert Level remained at 1 (on a scale of 1-4).
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.