Geologists Muslim Monoarta and Peter Jezek visited Dukono from 20-25 July. Activity had begun to intensify 4-7 days before their arrival and explosions of varying strength occurred about once every 10 seconds during their visit, ejecting bombs as large as 4 m in longest dimension. The bombs fell 200-250 m from the crater rim. Several 6-8-hour periods of quiescence interrupted the explosions, always at night. Ash emission was nearly continuous, with clouds rising as high as 10 km above the crater. The ash ranged from black sand-size particles to very fine light gray clay-size material.

On 21 July, fine light gray ash was blown N beyond the town of Galela, 15 km from the volcano. Moderate ashfall continued through most of the day on the 21st and during the morning of the 22nd. During the night of 23-24 July, the loudest explosions in many years rattled windows in Galela and incandescent ejecta were visible.

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, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. 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: M. Monoarta, Volcanology Division, GSI; P. Jezek, SI.