Report on Semeru (Indonesia) — June 2002
Bulletin of the Global Volcanism Network, vol. 27, no. 6 (June 2002)
Managing Editor: Richard Wunderman.
Semeru (Indonesia) Seismicity increases beginning in March 2002; Alert Level increased to 2
Please cite this report as:
Global Volcanism Program, 2002. Report on Semeru (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 27:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200206-263300
Semeru
Indonesia
8.108°S, 112.922°E; summit elev. 3657 m
All times are local (unless otherwise noted)
Since mid-July 2001, Semeru was at Alert Level 1 (on a scale of 1-4). On 8 March 2002 two pyroclastic flows traveled 2.5 km downslope to the Besuk Kembar river. The same day, tectonic and volcanic earthquakes increased, prompting the Volcanological Survey of Indonesia (VSI) to raise the Alert Level to 2. Tectonic and volcanic earthquakes continued, along with explosions, avalanches, pyroclastic flows, and tremor (table 7). Plumes, sometimes containing ash, were visible reaching up to 500 m above the summit (table 8).
Table 7. Seismicity registered at Semeru during 3 March-16 June 2002. "--" indicates that information was not reported. Courtesy VSI.
| Date | Deep volcanic | Shallow volcanic | Explosion | Avalanche | Local tectonic | Pyroclastic flow | Tremor | Far tremor |
| 03 Mar-10 Mar 2002 | 8 | 1 | 479 | 22 | 2 | 2 | -- | -- |
| 11 Mar-17 Mar 2002 | 1 | 2 | 444 | 21 | -- | -- | 3 | -- |
| 18 Mar-24 Mar 2002 | 2 | -- | 514 | 10 | 1 | -- | -- | -- |
| 25 Mar-31 Mar 2002 | 9 | 6 | 302 | 171 | 1 | -- | 2 | -- |
| 01 Apr-07 Apr 2002 | 26 | 2 | 415 | 278 | -- | -- | -- | -- |
| 08 Apr-14 Apr 2002 | 9 | -- | 509 | 141 | 3 | -- | 1 | -- |
| 15 Apr-21 Apr 2002 | 16 | 4 | 791 | 194 | -- | -- | -- | -- |
| 22 Apr-28 Apr 2002 | 6 | 0 | 585 | 64 | 3 | 0 | 5 | 14 |
| 29 Apr-05 May 2002 | 0 | 0 | 664 | 52 | 0 | 0 | 3 | 14 |
| 06 May-12 May 2002 | 5 | 0 | 783 | 62 | 0 | 0 | 0 | 15 |
| 13 May-19 May 2002 | 1 | 0 | 575 | 146 | 0 | 0 | 0 | 13 |
| 20 May-26 May 2002 | -- | -- | -- | -- | -- | -- | -- | -- |
| 27 May-02 Jun 2002 | 2 | 1 | 556 | 90 | 1 | -- | 2 | -- |
| 03 Jun-09 Jun 2002 | 2 | -- | 556 | 45 | -- | -- | 1 | -- |
| 10 Jun-16 Jun 2002 | 2 | -- | 637 | 31 | -- | -- | -- | -- |
Table 8. Plumes observed at Semeru during 8 March-16 June 2002. Courtesy VSI.
| Date | Plume Type | Plume height (above the summit) |
| 08 Mar 2002 | White-gray | 400 m |
| 12, 14, and 17 Mar 2002 | White-gray | 300-400 m |
| 19-23 Mar 2002 | White-gray | ~300-500 m |
| 25-31 Mar 2002 | White-gray | 300-500 m |
| 15-21 Apr 2002 | White-gray, medium pressure | 400 m |
| 22 Apr-26 May 2002 | White-gray, medium pressure | 400 m |
| 10-16 Jun 2002 | White-gray ash | 200-400 m |
On 31 March two tremor earthquakes occurred with amplitudes of ~3-17 mm. During mid-April, a tremor earthquake occurred with an amplitude of 0.2 mm. Lava avalanches continued to travel up to 750 m down to Besuk Kembar. Seismic signals thought to indicate local floods registered 15-21 April. Incandescence was observed up to 25 m above the crater rim during 1820-2025 on 18 April. During that time, seismicity was dominated by low-frequency earthquakes, with amplitudes of 2-3 mm. During 27 May-2 June ash explosions produced white-gray plumes that reached ~200-400 m above the summit, while lava avalanches traveled ~100 m away. Semeru remained at Alert Level 2 through at least 16 June 2002.
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: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).
