Report on Egon (Indonesia) — 28 January-3 February 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 January-3 February 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Egon (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 28 January-3 February 2004. Smithsonian Institution and US Geological Survey.
8.676°S, 122.455°E; summit elev. 1661 m
All times are local (unless otherwise noted)
Volcanic activity began at Egon on 29 January around 0400 when a landslide traveled down the volcano's E crater wall. Around 1700 an explosion produced a black ash cloud to a height of ~750 m above the summit. During 30-31 January, loud noises from the volcano were followed by emissions of gray ash clouds. In addition, there was a strong scent of sulfur every 50-60 minutes. Visual observations on the 31st revealed that a new solfatara tunnel (sulfur-rich fumarole) was created on the S side of the volcano. Small volcanic earthquakes, deep-volcanic earthquakes, and harmonic tremor were recorded. DVGHM put Egon at Alert Level 3 (on a scale of 1-4) beginning on 2 February. The volcano did not previously have an Alert Level. The Darwin VAAC reported that ash was not visible on satellite imagery.
The volcanism at Egon led to the evacuation of residents near the volcano on 29 January. According to a report by the United Nations Office for the Coordination of Humanitarian Affairs (OCHA), local authorities ordered the evacuation of the villages of Hale, Hebing, Egon Gahar, and Natakoli, which were in high-risk areas on the S side of the volcano. By 31 Jan, ~3,900 people had reached Maumere city, ~35 km away. As many as 6,000 people were evacuated by 1 February. At least one death was reported, although it was not clear if it resulted from the volcanic activity, evacuation process, or other causes. According to news reports, many of the evacuees suffered from respiratory problems, dengue fever, malaria, and diarrhea. There were also reports of looting in the evacuated villages.
Geologic Background. Gunung Egon, also known as Namang, sits astride the narrow waist of eastern Flores Island. The barren, sparsely vegetated summit region has a 350-m-wide, 200-m-deep crater that sometimes contains a lake. Other small crater lakes occur on the flanks. A lava dome forms the southern summit. Solfataric activity occurs on the crater wall and rim and on the upper S flank. Reports of historical eruptive activity prior to explosive eruptions beginning in 2004 were inconclusive. A column of "smoke" was often observed above the summit during 1888-1891 and in 1892. Strong "smoke" emission in 1907 reported by Sapper (1917) was considered by the Catalog of Active Volcanoes of the World (Neumann van Padang, 1951) to be an historical eruption, but Kemmerling (1929) noted that this was likely confused with an eruption on the same date and time from Lewotobi Lakilaki.
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC), UN Office for the Coordination of Humanitarian Affairs (OCHA), Khaleej Times, The Jakarta Post