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Iliboleng Volcano | Dr John Seach
Last updated: January 2026
(Also known as Ili Boleng)
Adonara Island, East Nusa Tenggara,
Indonesia
8.34 S, 123.25 E
summit elevation 1659 m
Stratovolcano
Iliboleng (Ili Boleng) is a stratovolcano in the southeast corner of Adonara Island, ~25 km east of Flores. The summit contains five craters with an irregular profile from past lava flows.
Warning: Iliboleng is dormant with no activity since 1991. Volcanic hazards are low. The region is seismically active due to the Sunda subduction zone.
Geology and Volcanology
Iliboleng is an andesitic stratovolcano in the Lesser Sunda arc, formed by subduction of the Indo-Australian Plate. The multiple summit craters indicate polygenetic activity with past explosive eruptions and lava flows shaping the irregular cone.
Historical eruptions have been mild explosive with ash emissions. Magmas are typical calc-alkaline andesites from arc subduction processes at ~100-150 km depth. No geothermal activity is prominent, consistent with dormancy. Due to long dormancy and remoteness, monitoring relies on regional seismic networks and satellite data from the Indonesian Centre for Volcanology and Geological Hazard Mitigation (PVMBG).
Current Activity (January 2026)
No volcanic activity has been recorded at Iliboleng since 1991. Satellite observations show no thermal anomalies or signs of unrest. The volcano remains dormant.
1991 Eruptions
Eruptions occurred at Iliboleng volcano on 3rd and 15th November 1991, with ash emissions to a height of 150 m above the crater. Shallow earthquakes were recorded.
1987 Eruption
An explosion occurred on 2nd October 1987, depositing ash on nearby villages.
1986 Eruptions
On 28th May 1986 an explosion occurred at Iliboleng volcano, ejecting incandescent material above the crater. Ash rain fell on Lamalota, Dua Muda, Tuawolo, and Kiwangona villages, forcing 570 residents to evacuate. Ash eruptions occurred on 18th July and 10th November. An ash eruption on 24th November was accompanied by rumbling. Dark ash column rose 1 km above the summit. The eruption lasted several hours.
1984 Eruptions
Eruptions occurred at Iliboleng volcano on 3rd January and 13th April 1984. Both eruptions produced black ash emissions up to 1 km high.
1983 Eruptions
Eruptions occurred at Iliboleng volcano on 11th May, 22nd September, and 24th November 1983. Black ash reached 500 m above the crater.
1982 Eruption
An ash eruption began on 17th November and sent a plume 1 km high. Ash fell on nearby villages.
1948 Eruption
An eruption occurred at Iliboleng volcano on 27th April 1948, with 500 cubic metres of material ejected.
Further reading
Neumann van Padang, M., 1951. Catalogue of the Active Volcanoes of the World, Including Solfatara Fields, Indonesia.
Iliboleng Volcano Eruptions
1991, 1987, 1986, 1983-1984, 1982, 1973-1974, 1951, 1950, 1949, 1948, 1944, 1927, 1925, 1909, 1904, 1888, 1885
Dormant since 1991