Report on Merapi (Indonesia) — 7 March-13 March 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 March-13 March 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, 7 March-13 March 2001. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
Visual and instrumental monitoring conducted by VSI personnel revealed that volcanic activity at Merapi had decreased; therefore on 7 March the Alert Level was reduced from 3 to 2 (on a scale of 1-4). During 27 February- 5 March, volcanic activity was dominated by an average of 100 lava avalanches per day. The avalanche material traveled to the SW, entering the Sat and Senowo rivers with runout distances of 2.3-2.5 km. On 6 March a pyroclastic flow deposited material up to 1.5 km down the Sat River.
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.