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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 8.342°S
  • 123.258°E

  • 1659 m
    5442 ft

  • 264220
  • Latitude
  • Longitude

  • Summit

  • Volcano

Most Recent Bulletin Report: February 1992 (BGVN 17:02) Cite this Report

Small ash eruptions

Ash eruptions occurred on 3 and 15 November 1991, ejecting columns to a maximum of ~150 m above the crater rim. Since then, an average of 47 shallow earthquakes have been recorded monthly, and a white vapor column continued to rise to ~ 50 m above the crater.

Information Contacts: W. Modjo and W. Tjetjep, VSI.

The Global Volcanism Program has no Weekly Reports available for Iliboleng.

Bulletin Reports - Index

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

12/1982 (SEAN 07:12) Small ash eruption

08/1983 (SEAN 08:08) Small plume photographed by Space Shuttle astronauts

05/1986 (SEAN 11:05) Explosion; grassfires from ashfall; 570 evacuated

07/1986 (SEAN 11:07) 800-m eruption cloud

11/1986 (SEAN 11:11) Renewed explosions after 12 days of seismicity

06/1987 (SEAN 12:06) Earthquakes increase; 300-m-high plume

07/1987 (SEAN 12:07) Volcanic earthquakes decline late in month

09/1987 (SEAN 12:09) Explosion deposits ash on nearby village

10/1987 (SEAN 12:10) Continued seismicity follows explosion

07/1989 (SEAN 14:07) Fumarolic emissions; felt earthquake

06/1991 (BGVN 16:06) Vapor and ash emission

02/1992 (BGVN 17:02) Small ash eruptions

Information is preliminary and subject to change. All times are local (unless otherwise noted)

December 1982 (SEAN 07:12) Cite this Report

Small ash eruption

VSI reported that an ash eruption began on 17 November at 0615. The ash column rose ~ 1 km and was blown N, causing thin ashfalls on nearby villages. The eruption ended after several hours. As of mid-Jan, no additional activity had been reported. Press sources noted that the eruption was preceded by a moderately strong, felt earthquake on 15 November at about 2300.

Information Contacts: A. Sudradjat and O. Mandraguna, VSI; M. Krafft, Cernay; Sinar Harapan, Jakarta.

August 1983 (SEAN 08:08) Cite this Report

Small plume photographed by Space Shuttle astronauts

[Photographs taken on 31 August (figure 1) and] 4 September by astronauts on Space Shuttle mission STS-8 showed small, relatively diffuse plumes long emerging from Iliboleng. [The 31 August plume extended at least 40 km and the 4 September plume was roughly 50-70 km long.]

Figure 1. Space Shuttle photograph (STS008-60-1840) taken on 31 August 1983 showing Iliboleng emitting a diffuse plume. Note that N is to the upper right; the plume is blowing almost due W. [Adonara Island covers 580 km2 and is 37 km long and 18 km wide. Lomblen Island, with its many volcanoes, is ESE of Adonara Island. To Adonara’s west, the E tip of Flores Island is visible; almost due S of Adonara is Solor Island.] Courtesy of C. Wood.

Information Contacts: C. Wood and R. Underwood, NASA, Houston.

May 1986 (SEAN 11:05) Cite this Report

Explosion; grassfires from ashfall; 570 evacuated

Iliboleng erupted on 28 May at 1735. A single explosion ejected incandescent material and caused ashfall on a nearby plantation and several villages both E and W of the summit (Lamalota, Dua Muda, Tuawolo, and Kiwangona). The incandescent ashfalls caused grass fires in the very dry area (no rain reported since February) that burned 700 hectares of grass W of the volcano and 250 hectares to the E. About 570 people were evacuated from several villages after the initial explosion and grass fires, but returned to their homes 31 May.

On 2 June at 0500, weather had cleared and a white vapor cloud of ~100 m height was reported. B-type earthquakes were recorded in the area on 21 May, but no more seismic data were available.

Information Contacts: A. Sudradjat, L. Pardyanto, and T. Casadevall, VSI.

July 1986 (SEAN 11:07) Cite this Report

800-m eruption cloud

Iliboleng erupted on 18 July at 1234, ejecting a cloud to ~ 800 m above the summit.

Information Contacts: L. Pardyanto, Olas, Kaswanda, Suratman, A. Sudradjat, and T. Casadevall, VSI.

November 1986 (SEAN 11:11) Cite this Report

Renewed explosions after 12 days of seismicity

Explosions occurred 10, 15, and 24 November. A gas and ash column emitted on 24 November at 0712 reached 1,000 m height and was blown NNW, covering 18.7 km2 with ~1 mm of ash. There were no casualties. Shallow volcanic seismicity began 30 October, with as many as 60 events/day. Eruption tremor was recorded for 1.5 minutes on 10 November.

Information Contacts: VSI; ANS.

June 1987 (SEAN 12:06) Cite this Report

Earthquakes increase; 300-m-high plume

Since 20 June, a plume has risen as much as 300 m above the summit. The number of shallow volcanic earthquakes increased to ~20/day 20-25 June, compared to 1/day previously. No eruptive activity has been reported since November.

Information Contacts: VSI.

July 1987 (SEAN 12:07) Cite this Report

Volcanic earthquakes decline late in month

During July, white plumes continued to be emitted to 300 m above the peak. Several shallow volcanic earthquakes were recorded daily during early July. In late July, seismic activity had returned to low background levels.

Information Contacts: VSI.

September 1987 (SEAN 12:09) Cite this Report

Explosion deposits ash on nearby village

A large explosion occurred on 2 October at 2252, depositing a light dusting of ash on villages near the volcano.

Information Contacts: VSI.

October 1987 (SEAN 12:10) Cite this Report

Continued seismicity follows explosion

A large explosion on 2 October at 2252 deposited a light dusting of ash in about a 15 km2 area around the volcano. During the week of 9-15 October, white fume was continuously present above the crater, rising to heights of 300 m. During that week, about 13 tectonic and 11 volcanic events were recorded/day.

Information Contacts: VSI.

July 1989 (SEAN 14:07) Cite this Report

Fumarolic emissions; felt earthquake

In July, fumarole temperatures in the crater were 60-70°C. On 15 July, an MM II earthquake was felt. The number and types of earthquakes recorded were: 131 distant tectonic, three local tectonic, two volcanic A-type, and 144 volcanic B-type. The volcano's level of activity is slightly higher than normal.

Information Contacts: VSI.

June 1991 (BGVN 16:06) Cite this Report

Vapor and ash emission

Vapor and ash were continuously emitted to 100-850 m height, beginning 8 May and continuing through June. Shallow volcanic earthquakes were recorded 15-25 times/week (figure 2), but no explosion earthquakes were recorded. Tectonic earthquakes averaged 14-24/week.

Figure 2. Monthly number of earthquakes at Iliboleng, January 1990-May 1991. Courtesy of VSI.

Information Contacts: W. Modjo, VSI.

February 1992 (BGVN 17:02) Cite this Report

Small ash eruptions

Ash eruptions occurred on 3 and 15 November 1991, ejecting columns to a maximum of ~150 m above the crater rim. Since then, an average of 47 shallow earthquakes have been recorded monthly, and a white vapor column continued to rise to ~ 50 m above the crater.

Information Contacts: W. Modjo and W. Tjetjep, VSI.

Basic Data

Volcano Number

Last Known Eruption



1993 CE

1659 m / 5442 ft


Volcano Types


Rock Types

Basalt / Picro-Basalt
Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone
Crustal thickness unknown


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Geological Summary

Iliboleng stratovolcano was constructed at the SE end of Adonara Island across a narrow strait from Lomblen Island. The volcano is capped by multiple, partially overlapping summit craters. Lava flows modify its profile, and a cone low on the SE flank, Balile, has also produced lava flows. Historical eruptions, first recorded in 1885, have consisted of moderate explosive activity, with lava flows accompanying only the 1888 eruption.


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Kusumadinata K, 1979. Data Dasar Gunungapi Indonesia. Bandung: Volc Surv Indonesia, 820 p.

Neumann van Padang M, 1951. Indonesia. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 1: 1-271.

Stolz A J, Varne R, Davies, G R, Wheller G E, Foden J D, 1990. Magma source components in an arc-continent collision zone: the Flores-Lembata sector, Sunda arc, Indonesia. Contr Mineral Petr, 105: 585-601.

Sudradjat A, 1977. (pers. comm.).

Wheller G E, Varne R, Foden J D, Abbott M J, 1987. Geochemistry of Quaternary volcanism in the Sunda-Banda arc, Indonesia, and three-component genesis of island-arc basaltic magmas. J Volc Geotherm Res, 32: 137-160.

Eruptive History

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1993 Jun (?) 1993 Jul Confirmed 1 Historical Observations
1991 Nov 3 1991 Nov 15 Confirmed 1 Historical Observations
1991 May 8 1991 Jun 30 (in or after) Confirmed 1 Historical Observations
1987 Oct 2 1987 Oct 2 Confirmed 2 Historical Observations
1986 May 28 1986 Nov 24 Confirmed 1 Historical Observations
1983 May 11 1984 Apr 13 Confirmed 2 Historical Observations
1982 Nov 17 1982 Nov 17 Confirmed 2 Historical Observations
1973 Apr 1974 Apr Confirmed 2 Historical Observations
1951 Unknown Confirmed 2 Historical Observations
1950 Mar 1950 Aug (?) Confirmed 2 Historical Observations
1949 Jun 12 Unknown Confirmed 2 Historical Observations
1949 Feb 4 Unknown Confirmed 2 Historical Observations
1948 Apr 29 Unknown Confirmed 2 Historical Observations
1944 Aug 1944 Oct Confirmed 2 Historical Observations
1927 Unknown Confirmed 2 Historical Observations
1925 Unknown Confirmed 2 Historical Observations
1909 Nov 9 Unknown Confirmed 2 Historical Observations
1904 Unknown Confirmed 2 Historical Observations
1888 Unknown Confirmed 2 Historical Observations
1885 Sep 1885 Oct Confirmed 2 Historical Observations

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Bolin | Wakka | Lamatelang


Feature Name Feature Type Elevation Latitude Longitude
Balile Cone 262 m

Photo Gallery

Iliboleng volcano at the SE end of Adonara Island, east of Flores Island, is a symmetrical stratovolcano with many partially overlapping summit craters. Iliboleng is seen here from Bukit Tomu, north of the volcano. Explosive eruptions from the summit crater have been recorded since 1885. Only one historical eruption, in 1888, produced a lava flow.

Photo by Willem Rohi, 1994 (Volcanological Survey of Indonesia).
Iliboleng volcano rises above the Boleng strait between Adonara and Lomblen Islands, at the eastern end of the Lesser Sunda (Nusa Tenggara) Islands. The symmetrical volcano, which occupies the SE corner of Adonara, is seen here from the NE tip of the island. The 1659-m-high stratovolcano, the only historically active volcano on the island, is one of the most active in the Lesser Sundas.

Photo by O. Rikman, 1985 (Volcanological Survey of Indonesia).
Four volcanoes are seen in this NASA Space Shuttle image (with north to the upper left) of Solor (lower left), Adonara (upper left), and Lembata (right) Islands. Ililabalekan volcano on SW Lembata (formerly Lomblen) Island is the only one of these without historical eruptions, although fumaroles are found near its summit. A satellitic cone was constructed on the SE flank of the steep-sided volcano, and four craters, one of which contains a lava dome and two small explosion pits, occur at the summit of Mount Labalekan.

NASA Space Shuttle image ISS009-E-7480, 2004 (
An eruption at Iliboleng began on May 11, 1983, when thick black smoke rose to 500 m. Ash and incandescent ejecta was reported on July 13, fine ash occasionally fell from the plume on July 15. On September 4 space shuttle astronauts photographed this small diffuse plume 50-70 km long, and thick black smoke was reported again on September 22. A 500 m gray smoke plume was seen for a few minutes on November 24, and thick black smoke clouds (to max. 1 km) were emitted on January 3 and April 13, 1984.

NASA Space Shuttle image STS008-50-1840, 1983 (

Smithsonian Sample Collections Database

There are no samples for Iliboleng in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites

Large Eruptions of Iliboleng Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
MODVOLC - HIGP MODIS Thermal Alert System Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
MIROVA Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.