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Report on Ijen (Indonesia) — August 2002


Ijen

Bulletin of the Global Volcanism Network, vol. 27, no. 8 (August 2002)
Managing Editor: Richard Wunderman.

Ijen (Indonesia) Small explosion in late July 2002 accompanies increased seismicity; ash emissions

Please cite this report as:

Global Volcanism Program, 2002. Report on Ijen (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 27:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200208-263350



Ijen

Indonesia

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

All times are local (unless otherwise noted)


During 27 May through at least 8 September 2002 at Ijen, activity was above background levels. Seismicity was dominated by shallow volcanic (B-type) earthquakes. One small explosion occurred on 29 July, accompanying an increase in the number of B-type earthquakes (table 4). Ash was emitted during late July through mid-August. Continuous tremor occurred with a maximum amplitude of 0.5-6 mm. Fog obscured the view during most of the reporting period, but when the summit was visible, plumes were observed reaching up to 125 m above the volcano. Ijen remained at Alert Level 2.

Table 4. Earthquakes and plumes reported at Ijen during 27 May-8 September 2002. Courtesy VSI.

Date Deep volcanic earthquakes (A-type) Shallow volcanic earthquakes (B-type) Max amplitude of continuous tremor Small explosion Tectonic earthquakes Plume Details
27 May-02 Jun 2002 -- 6 0.5-4 mm -- -- White-medium plume reached 50-125 m above the summit.
03 Jun-09 Jun 2002 -- 10 0.5-4 mm -- -- White-medium plume reached 50 m above the summit.
10 Jun-16 Jun 2002 -- 12 0.5-4 mm -- 2 --
17 Jun-23 Jun 2002 1 6 0.5-4 mm -- 4 --
24 Jun-30 Jun 2002 -- 2 0.5-6 mm -- 2 --
01 Jul-07 Jul 2002 -- 1 0.5-5 mm -- 2 --
08 Jul-14 Jul 2002 -- 13 0.5-4 mm -- 2 --
15 Jul-21 Jul 2002 -- 23 0.5-4 mm -- 1 --
22 Jul-28 Jul 2002 -- 22 0.5-4 mm -- 10 --
29 Jul-04 Aug 2002 4 40 0.5-3 mm 1 on 29 July -- White-gray ash plume ~50 m above summit drifted E.
05 Aug-11 Aug 2002 -- 31 0.5-6 mm -- 2 White-gray ash plume ~50 m above summit drifted E.
12 Aug-18 Aug 2002 -- 34 0.5-2 mm -- 4 White-gray ash plume 50-75 m above summit drifted E.
19 Aug-25 Aug 2002 -- 47 0.5-4 mm -- 8 --
26 Aug-01 Sep 2002 2 59 0.5-4 mm -- 3 --
02 Sep-08 Sep 2002 -- 65 0.5-3 mm -- 6 --

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.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).