Report on Merapi (Indonesia) — March 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 3 (March 1991)
Managing Editor: Lindsay McClelland.
Merapi (Indonesia) Slight increase in seismicity; no apparent dome growth
Please cite this report as:
Global Volcanism Program, 1991. Report on Merapi (Indonesia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199103-263250.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
Seismic activity increased slightly in early March, from two events/week to an average of 9/week. A swarm of small-amplitude (plus three large-amplitude) shallow volcanic earthquakes occurred on 10 March. The lava dome volume was stable at 6.8 x 106 m3, the same as reported in August 1990 (15:07).
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.
Information Contacts: W. Modjo, VSI; AP.