Report on Gede-Pangrango (Indonesia) — April 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 4 (April 1991)
Managing Editor: Lindsay McClelland.
Gede-Pangrango (Indonesia) Earthquake swarm
Please cite this report as:
Global Volcanism Program, 1991. Report on Gede-Pangrango (Indonesia). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 16:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199104-263060.
6.77°S, 106.965°E; summit elev. 3008 m
All times are local (unless otherwise noted)
A swarm of 100 volcanic earthquakes (40 deep and 60 shallow) was recorded on 29 April, an increase from the previous daily average of 10-15 events. Tectonic earthquakes averaged 1-2/day. Seismicity had been increasing since February. No surface activity was observed.
Geologic Background. Gede volcano is one of the most prominent in western Java, forming a twin volcano with Pangrango volcano to the NW. The major cities of Cianjur, Sukabumi, and Bogor are situated below the volcanic complex to the E, S, and NW, respectively. Gunung Pangrango, constructed over the NE rim of a 3 x 5 km caldera, forms the high point of the complex at just over 3000 m elevation. Many lava flows are visible on the flanks of the younger Gunung Gede, including some that may have been erupted in historical time. The steep-walled summit crater has migrated about 1 km NNW over time. Two large debris-avalanche deposits on its flanks, one of which underlies the city of Cianjur, record previous large-scale collapses. Historical activity, recorded since the 16th century, typically consists of small explosive eruptions of short duration.
Information Contacts: W. Modjo, VSI.