Raung volcano was last discussed in BGVN 27:07, when a pilot reported ash plumes to 4.6 km altitude in early June 2002. That issue of theBulletin also noted a Volcanological Survey of Indonesia (VSI) comment that Raung had been erupting for at least a decade, with recent eruptions being events within a single, broader eruptive period.

The Darwin Volcanic Ash Advisory Center (VAAC) subsequently received reports that on 12 August 2002 ash was visible drifting NW of Raung around the summit level. The summit was partially obscured by clouds and no ash was identified on satellite imagery. On 25 August 2002, based on pilot observations and satellite imagery, the VAAC reported a visible ash plume rising to about 9.2 km, drifting to the W at high levels and to the E at lower levels.

The Darwin VAAC has an archive of their reports available on their website. Those for Raung are summarized in table 1. The last set of reports (25 August 2002) discussed a plume becoming increasingly diffuse over a 16.5-hour interval.

Table 1. Dates and principal comments in Darwin VAAC reports concerning Raung, July 1999-February 2004. Dates and times are not local but instead refer to the Prime Meridian, for example 04/2240Z means the fourth day of the stated month at 2240 UMT. Similar or duplicate message are not shown. In general, ash cloud trajectory information has been omitted. In a few cases the VAAC delineated bounding area surrounding an observed ash cloud ("OBS ASH CLOUD"), delineated with a series of latitude and longitude coordinates (eg. S00700, E11000; which translates to 7 degrees S, 110 degrees E). In the original reports, altitudes were given in shorthand (eg. FL 100, which corresponds to 10,000 feet altitude; 3,048.0 m altitude, but typically not known to better than two significant figures and thus here rounded to ~ 3.0 km altitude). Courtesy of the Darwin VAAC.

Geological Summary. Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively.

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