Report on Tangkubanparahu (Indonesia) — October 1983
Scientific Event Alert Network Bulletin, vol. 8, no. 10 (October 1983)
Managing Editor: Lindsay McClelland.
Tangkubanparahu (Indonesia) Seismicity continues to increase
Please cite this report as:
Global Volcanism Program, 1983. Report on Tangkubanparahu (Indonesia). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 8:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198310-263090.
6.77°S, 107.6°E; summit elev. 2084 m
All times are local (unless otherwise noted)
Seismicity continued to increase through mid-October but no surface changes have been noted. Tectonic earthquakes and both A-and B-type microtremors were recorded. A-type events occurred irregularly, usually at 1-3 per day, but as many as five were detected on several days. B-type earthquakes increased substantially, as shown in table 1.
|Time Period||Daily Average||Maximum / day|
|Aug 1983 (first weeks)||10||19|
|Aug 1983 (last week)||14||25|
|Sep 1983 (first half)||70||120|
|Sep 1983 (second half)||57||103|
|Oct 1983 (first half)||72||127|
Ground deformation did not show regular changes. From 10 to 25 mm of irregular inflation and deflation were detected but their significance is doubtful. Fumarole temperatures remained stable at 96°C in the three fumarole fields (Baru, Ratu, and Upas). The previously declared forbidden zone of 3-km-radius remained in effect.
Geologic Background. Tangkubanparahu (also known as Tangkuban Perahu) is a broad shield-like stratovolcano overlooking Indonesia's former capital city of Bandung. The volcano was constructed within the 6 x 8 km Pleistocene Sunda caldera, which formed about 190,000 years ago. The volcano's low profile is the subject of legends referring to the mountain of the "upturned boat." The rim of Sunda caldera forms a prominent ridge on the western side; elsewhere the caldera rim is largely buried by deposits of Tangkubanparahu volcano. The dominantly small phreatic historical eruptions recorded since the 19th century have originated from several nested craters within an elliptical 1 x 1.5 km summit depression.
Information Contacts: A. Sudradjat, VSI.