Global Volcanism Program | Report on Semeru (Indonesia)

Report on Semeru (Indonesia) — July 2003

Bulletin of the Global Volcanism Network, vol. 28, no. 7 (July 2003)
Managing Editor: Edward Venzke.

Semeru (Indonesia) Ash plumes, pyroclastic flows, and high seismicity continue through June

Please cite this report as:

Global Volcanism Program, 2003. Report on Semeru (Indonesia) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 28:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200307-263300

Semeru

Indonesia

8.108°S, 112.922°E; summit elev. 3657 m

All times are local (unless otherwise noted)

According to the Volcanological Survey of Indonesia (VSI), activity during 24 March-29 June 2003 was continually at a high level. Explosions produced white-gray ash plumes several times per week that rose 300-600 m over the summit. Pyroclastic flows on 27 March had a run-out distance of 3,750 m toward Besuk Bang. More pyroclastic-flow events on 14 and 18 April traveled toward Besuk Bang (3,500 m) and Besuk Kembar (2,500 m). On 11 May a pyroclastic flow entered Besuk Kembar and extended 1,500 m. Seismographs continually recorded earthquake activity (table 12). The hazard status remained at Level 2 (on a scale of 1-4) throughout the report period.

Table 12. Seismicity at Semeru, 24 March-29 June 2003. Courtesy of VSI.

Date	Explosion	Avalanche	Tremor	Other	Tectonic
24 Mar-30 Mar 2003	794	48	17	1 flood; 12 PF	6
31 Mar-06 Apr 2003	738	28	12	2 shallow; 2 PF	6
07 Apr-13 Apr 2003	698	33	11	7 PF	6
14 Apr-20 Apr 2003	697	70	20	12 PF	7
21 Apr-27 Apr 2003	713	82	16	1 deep volc	9
28 Apr-04 May 2003	651	36	31	1 deep volc	2
05 May-11 May 2003	846	37	27	2 shallow volc; 1 PF	5
12 May-18 May 2003	730	41	38	1 shallow volc	3
19 May-25 May 2003	748	17	17	--	8
26 May-01 Jun 2003	585	27	26	--	8
02 Jun-08 Jun 2003	758	29	24	--	4
09 Jun-15 Jun 2003	600	27	63	2 deep volc	13
16 Jun-22 Jun 2003	711	20	13	1 shallow volc	8
23 Jun-29 Jun 2003	838	33	--	--	4

Geological Summary. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

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