Report on Merapi (Indonesia) — 30 January-5 February 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
30 January-5 February 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, 30 January-5 February 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 21-27 January, 979 lava avalanches traveled down Merapi's flanks, predominately SW toward the upstream portions of the Sat and Bebeng rivers, and partly WSW to the Lamat and Senowo rivers. The maximum run-out distance was ~2.75 km. Several small pyroclastic flows traveled up to ~1.5 km to the upstream portions of the Sat and Bebeng rivers; two on the 23rd, one on the 24th, and two on the 25th. 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.