Report on Merapi (Indonesia) — 26 April-2 May 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 April-2 May 2006
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2006. Report on Merapi (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 26 April-2 May 2006. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
On 28 April, CVGHM observed a lava flow from Merapi traveling ~1.5 km SW to the Lamat River. On the 28th, seismicity was dominated by multiphase earthquakes. Signals from landslides, rockfalls, and low-frequency events were also recorded. According to news reports, around 27 April nearly 2,000 villagers were evacuated from Sidorejo and Tegalmulyo villages on the volcano's flanks. On the 27th, small amounts of ash fell in Gemer village about 5 km from Merapi's summit. Merapi remained at Alert Level 3 (on a scale of 1-4).
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.