Report on Merapi (Indonesia) — 14 February-20 February 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 February-20 February 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, 14 February-20 February 2001. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
VSI reported that after the large 10 February eruption volcanic activity decreased in intensity. Lava avalanches and pyroclastic flows continued, but were smaller than they were the previous week. During 10 to 13 February pyroclastic flows entered the Sat, Lamat, Senowo, and Bebeng rivers to a maximum runout distance of 2-3 km, in comparison to ~4.5 km the previous week. After 13 February lava avalanches and pyroclastic flows traveled 1.5-2.5 km to the WSW and lasted 1-2 hours. According to the VSI, high temperatures around Merapi indicate that magma is near the surface. The W and S sides of "lava dome 2001" grew and covered "lava dome 1997" to the S. Several fumaroles appeared to mark a fracture along the area where the 10 February eruption occurred. Fractures formed in a similar matter prior to the November 1994 eruption. The volcano remained at Alert Level 4, the highest level.
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.