Report on Merapi (Indonesia) — 29 August-4 September 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
29 August-4 September 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Merapi (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 29 August-4 September 2001. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
During 13-26 August approximately 380 lava avalanches were observed travelling SW, extending a maximum distance of 2.8 km mainly down the Sat and Lamat rivers, and to a lesser extent towards the Senowo and Bebeng rivers. Seismic activity consisted primarily of avalanche earthquakes, as it had for the previous 2 weeks. The volcano remained at Alert Level 2 (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.