During 2004 and 2005, Dukono continued to emit ash plumes as it has for many decades. This report first summarizes available reports from Indonesia's Center of Volcanology and Geological Hazard Mitigation (CVGHM).

David Rothery and Charlotte Saunders previously discussed MODIS thermal alerts up to April 2004 in our last report (BGVN 29:06). Since that time, and as recently as 1 August 2006, the only MODIS thermal alerts were detected on 4 October 2004.

CVGHM observations, 2004-2005. During this interval, the volcano's hazard status stood at Level 2 (Yellow).

During 31 May to 31 August 2004 small explosions were accompanied by rumbling sounds and the release of white to gray-black ash. The emissions occurred at a relatively constant frequency and intensity. The ash-bearing clouds reached up to ~ 500 m above the summit. Ash discharges and rumbling were constant.

Eruptive behavior continued throughout 2005. From 24 to 30 January explosions often ejected ash, and dark gray ash plumes reached 200-600 m above the summit. On 9 May an ash eruption was accompanied by an explosive sound repeated 27 times. Ejections the week of 26 September-2 October contained ash and, occasionally, larger pyroclastic material. Explosions occurred about 15 times a day, sending plumes 100-400 m high. Thousands of explosions were documented during the next two weeks (table 1). Ash columns rose 100-950 m above the summit.

Table 1. Summary of types and numbers of seismic/volcanic events occurring at Dukono during late September through mid-October 2005. Courtesy of CVGHM.

Aviation reports, 2004-2006. A large table contains aviation observations from 31 December 2003 through 12 January 2006 from the Darwin VAAC (table 2), although not all the VAAC's original reports were inspected. Some of the reported eruptions during that time generated plumes visible on satellite imagery to distances as far as 200 km. Plumes often rose to ~ 3 km altitude.

Table 2. Events reported for Dukono for the interval 31 December 2003-12 January 2006 (as taken from summaries of collaborative Darwin VAAC and CVGHM reports presented in USGS-Smithsonian Weekly Reports). Courtesy of Darwin VAAC and CVGHM.

Geological Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, have occurred since 1933. During a major eruption in 1550 CE, a lava flow filled in the strait between Halmahera and the N-flank Gunung Mamuya cone. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Center (VAAC) (URL: http://www.bom.gov.au); HIGP Thermal Alerts Team, Hawai'i Institute of Geophysics and Planetology (HIGP) / School of Ocean and Earth Science and Technology (SOEST), University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).