Report on Merapi (Indonesia) — 27 February-5 March 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
27 February-5 March 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Merapi (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 27 February-5 March 2002. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
During 25 February-3 March 88 incandescent lava avalanches were observed traveling down Merapi's flanks, predominately SW to the upstream portions of the Lamat, Sat, and Senowo rivers and partly in a more southerly direction towards Bebeng River. The maximum run-out distance was ~2.5 km. Four minor pyroclastic flows were observed during the report period; three occurred on 25 February and one on 3 March. The flows traveled SSW as far as 1 km to the upstream portion of the Bebeng River. Seismicity at the volcano was similar to the previous week. Merapi 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.