Report on Ijen (Indonesia) — July 1999
Bulletin of the Global Volcanism Network, vol. 24, no. 7 (July 1999)
Managing Editor: Richard Wunderman.
Ijen (Indonesia) Two phreatic eruptions at the active crater lake on 28 June
Please cite this report as:
Global Volcanism Program, 1999. Report on Ijen (Indonesia). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 24:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199907-263350.
8.058°S, 114.242°E; summit elev. 2769 m
All times are local (unless otherwise noted)
Two phreatic eruptions occurred at the Sibanteng location inside the active crater lake at 0510 on 28 June. An accompanying detonation was heard 2 km from the summit and volcanic tremor was recorded with an amplitude of 0.5 to 1 mm. Seismicity continued at the same low level as the previous week. Other details regarding the eruption remain undisclosed.
Geologic Background. The Ijen volcano complex at the eastern end of Java consists of a group of small stratovolcanoes constructed within the large 20-km-wide Ijen (Kendeng) caldera. The north caldera wall forms a prominent arcuate ridge, but elsewhere the caldera rim is buried by post-caldera volcanoes, including Gunung Merapi, which forms the high point of the complex. Immediately west of the Gunung Merapi stratovolcano is the historically active Kawah Ijen crater, which contains a nearly 1-km-wide, turquoise-colored, acid lake. Picturesque Kawah Ijen is the world's largest highly acidic lake and is the site of a labor-intensive sulfur mining operation in which sulfur-laden baskets are hand-carried from the crater floor. Many other post-caldera cones and craters are located within the caldera or along its rim. The largest concentration of cones forms an E-W zone across the southern side of the caldera. Coffee plantations cover much of the caldera floor, and tourists are drawn to its waterfalls, hot springs, and volcanic scenery.
Information Contacts: R. Sukhyar and Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).