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Gunung Api Wetar Volcano | Dr John Seach
Last updated: January 2026
Banda Sea, Maluku,
Indonesia
6.64 S, 126.65 E
summit elevation 282 m
Stratovolcano (island)
Gunung Api Wetar is a small, isolated island stratovolcano in the Banda Sea, north of Wetar Island. The round island is built primarily from lava flows with a central crater containing a small cone. Three prominent landslides are visible on the slopes, indicating past flank instability.
The volcano rises ~4000 m from the seafloor, forming a steep conical island. Historical activity was effusive with lava flows reaching the sea.
Warning: Gunung Api Wetar is dormant with no activity since the 17th century. Volcanic hazards are low, but the remote island location limits rapid response to any future unrest.
Geology and Volcanology
Gunung Api Wetar is part of the complex Banda arc, a transition zone where subduction of the Indo-Australian Plate gives way to continental collision with the Australian margin. The volcano's lavas are notably low in potassium despite the deep Benioff Zone (~400-500 km), suggesting magma derivation not directly from typical subduction melting but possibly from shallower asthenospheric sources or intra-plate processes influenced by arc rifting.
The island's morphology reflects multiple phases of cone building, effusive lava flow emplacement, and flank collapse (evident in three prominent landslides). The central crater and small inner cone indicate relatively recent activity in geological terms. The volcano's isolated position in the Banda Sea contributes to its distinct composition compared to typical Sunda arc volcanoes.
The Banda arc is known for extreme magma diversity due to mixed subduction and collision processes, with potassic signatures in some centres. Gunung Api Wetar's low-K lavas highlight the variability in this transitional setting. No active geothermal system is documented, consistent with dormancy.
Due to its remote island setting, monitoring relies on regional seismic networks, satellite detection of activity, and occasional surveys from the Indonesian Centre for Volcanology and Geological Hazard Mitigation (PVMBG).
Current Activity (January 2026)
No volcanic activity has been recorded at Gunung Api Wetar since historical times. Satellite observations show no thermal anomalies, gas emissions, or signs of unrest. The volcano remains dormant.
1512 Eruption
In 1512 Portuguese sailors observed streams of fire flowing from the summit to the sea.
Further reading
Wheller, G. E., et al. "Geochemistry of Quaternary volcanism in the Sunda-Banda arc, Indonesia, and three-component genesis of island-arc basaltic magmas." Journal of Volcanology and Geothermal Research 32.1-3 (1987): 137-160.
Gunung Api Wetar Volcano Eruptions
1699, 1512
Dormant since 1699