Report on Egon (Indonesia) — 7 July-13 July 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 July-13 July 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, 7 July-13 July 2004. Smithsonian Institution and US Geological Survey.
8.676°S, 122.455°E; summit elev. 1661 m
All times are local (unless otherwise noted)
During 5-11 July, observers watching Egon volcano saw it emit white plumes of variable density that typically rose 25-75 m above the summit. The seismograph recorded a continuous series of 'emission earthquakes' with amplitudes of 2 mm. Egon's hazard status remained at Alert Level 2 (on a scale of 1-4).
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.