Report on Merapi (Indonesia) — 12 April-18 April 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 April-18 April 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, 12 April-18 April 2006. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
According to CVGHM, volcanic activity began to increase at Merapi on 11 April, and on 12 April at 1500 they raised the Alert level from 2 to 3 (on a scale of 1-4). They reported that an eruption could occur at any time and no one was permitted within 8 km of the summit. According to news reports, authorities informed people living in villages near the volcano to be prepared for possible evacuations.
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.