Report on Ijen (Indonesia) — 21 March-27 March 2012
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 21 March-27 March 2012
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2012. Report on Ijen (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 21 March-27 March 2012. Smithsonian Institution and US Geological Survey.
8.058°S, 114.242°E; summit elev. 2769 m
All times are local (unless otherwise noted)
On 24 March, CVGHM reported that Ijen's lake water chemistry changed during 10 January-17 March, exhibiting a significant increase in carbon dioxide, especially after 5 February, and an increase in acidity. The lake surface temperature increased from 28.8 degrees Celsius on 3 March to 45.1 degrees Celsius on 17 March. The lake water temperature at a depth of 5 m also rose from 42.7 to 44.7 degrees Celsius on 3 and 17 March, respectively. Seismicity increased starting in March. The Alert Level remained at 2 (on a scale of 1-4). [Correction: the Alert Level remained at 3.]
Geological Summary. The Ijen volcano complex at the eastern end of Java consists of a group of small stratovolcanoes constructed within the 20-km-wide Ijen (Kendeng) caldera. The north caldera wall forms a prominent arcuate ridge, but elsewhere the rim was 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. Kawah Ijen is the site of a labor-intensive mining operation in which baskets of sulfur 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; nearby waterfalls and hot springs are tourist destinations.