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Report on Ijen (Indonesia) — April 2002

Bulletin of the Global Volcanism Network, vol. 27, no. 4 (April 2002)
Managing Editor: Richard Wunderman.

Ijen (Indonesia) Continuous tremor, volcanic and tectonic earthquakes through April 2002

Please cite this report as:

Global Volcanism Program, 2002. Report on Ijen (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 27:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200204-263350.

Volcano Profile |  Complete Bulletin


Ijen

Indonesia

8.058°S, 114.242°E; summit elev. 2769 m

All times are local (unless otherwise noted)


During 7 January through at least 19 May 2002 at Ijen, seismicity was higher than normal. Shallow volcanic and tectonic earthquakes were recorded (table 3). One small explosion earthquake was recorded during the week of 28 January-3 February. A total of three deep volcanic (A-type) earthquakes were registered during early May. Continuous tremor occurred with a maximum amplitude of 0.5-4 mm until mid-March, when it decreased to 0.5-2 mm. During 8-14 April, a white, thin, medium-pressure plume rose 50 m above the summit crater. The following week, the tremor increased to 0.5-6 mm maximum amplitude and remained at similar levels through at least 19 May. The Alert Level remained at 2 during the report period.

Table 3. Earthquakes recorded at Ijen during 7 January through 19 May 2002. Courtesy VSI.

Date Shallow volcanic earthquakes (B-type) Tectonic earthquakes
07 Jan-13 Jan 2002 5 2
14 Jan-20 Jan 2002 -- --
21 Jan-27 Jan 2002 -- --
28 Jan-03 Feb 2002 9 1
04 Feb-10 Feb 2002 1 3
11 Feb-17 Feb 2002 4 1
18 Feb-24 Feb 2002 8 --
25 Feb-03 Mar 2002 9 3
04 Mar-10 Mar 2002 12 4
11 Mar-17 Mar 2002 2 2
18 Mar-24 Mar 2002 1 --
25 Mar-31 Mar 2002 2 2
01 Apr-07 Apr 2002 -- 2
08 Apr-14 Apr 2002 2 --
15 Apr-21 Apr 2002 9 2
22 Apr-28 Apr 2002 11 1
29 Apr-05 May 2002 70 4
06 May-12 May 2002 42 3
13 May-19 May 2002 22 4

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: Dali Ahmad, Volcanological Survey of Indonesia (VSI) (URL: http://www.vsi.esdm.go.id/).