Report on Marapi (Indonesia) — January 2005
Bulletin of the Global Volcanism Network, vol. 30, no. 1 (January 2005)
Managing Editor: Richard Wunderman.
Marapi (Indonesia) Small eruptions and seismicity during August to October 2004
Please cite this report as:
Global Volcanism Program, 2005. Report on Marapi (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 30:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200501-261140
Marapi
Indonesia
0.38°S, 100.474°E; summit elev. 2885 m
All times are local (unless otherwise noted)
The most recent previous explosive activity at Marapi peaked during 13-18 April 2001, when a total of 150 explosions occurred that sent ash plumes to 2 km above the summit (BGVN 27:01). This report covers the interval 5 August to 10 October 2004. On 5 August 2004 Marapi generated a small eruption with a gray to black ash cloud that rose to 500-1,000 m above the summit. Its hazard status was raised to Alert Level II (yellow), where it remained throughout this period.
Total numbers of seismic events from 2 August through 10 October 2004 are listed in table 2. During some weeks in August the number of earthquakes increased markedly. A thin white plume rose to 50 m above the summit on 10 August. During 16-29 August a thin white-gray plume rose to ~ 75-100 m. Similar plumes rose to ~ 50 m during 27 September-3 October and to ~ 300 m during 4-10 October. Seismic signals inferred to be related to emissions were elevated during several weeks of the reporting interval, particularly in August (table 2).
Table 2. A summary of volcanic seismicity at Marapi during 2 August to 10 October 2004. Courtesy of DVGHM.
| Date | Volc A | Volc B | Tremor | Emission |
| 02 Aug-08 Aug 2004 | 1 | 11 | -- | -- |
| 09 Aug-15 Aug 2004 | 2 | 6 | -- | 20 |
| 16 Aug-22 Aug 2004 | -- | 3 | -- | 21 |
| 23 Aug-29 Aug 2004 | -- | 3 | 2 | 14 |
| 20 Sep-26 Sep 2004 | -- | -- | -- | -- |
| 27 Sep-03 Oct 2004 | 1 | -- | -- | -- |
| 04 Oct-10 Oct 2004 | 3 | -- | -- | 8 |
There were no MODIS-MODVOLC alerts at Marapi during 2004.
Geological Summary. Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra's most active volcano. This massive complex stratovolcano rises 2,000 m above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been reported in historical time.
Information Contacts: Directorate of Volcanology and Geological Hazard Mitigation (DVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Center (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/).
