Report on Ijen (Indonesia) — 9 May-15 May 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
9 May-15 May 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Ijen (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 May-15 May 2012. Smithsonian Institution and US Geological Survey.
8.058°S, 114.242°E; summit elev. 2769 m
All times are local (unless otherwise noted)
CVGHM reported that during 1-30 April white plumes from Ijen rose 100-200 m above the crater; during 1-11 May diffuse white plumes rose 50-100 m. From the beginning of April until 13 May the amplitude and number of earthquakes gradually decreased and the crater lake water temperature decreased by eight degrees Celsius. The Alert Level was lowered to 2 (on a scale of 1-4) on 13 May.
Geological Summary. 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.