- Bougainville is a large volcanic island arc island (120km long) that had similar geological evolution to the nearby Solomon Islands to the southeast.
- Originally (~45 MYA) the Pacific Plate was subducting below the Pacific Plate, and some of the island’s early volcanic systems and the island itself were created on the southern end of the current island.
- Then (~10 MYA) as the thick Ontong Java Plateau approached and impacted the arc, the subduction polarity reversed, with the Australian Plate then subducting beneath the Pacific Plate. This lead to additional major volcanic systems being created.
- Today there are 10# major volcanic systems visible with three active volcanoes (Balbi, Bagana, and Loloru). Balbi and Loloru have surface manifestations including thermal springs and fumaroles. Bagana has an actively erupting, non-explosive effusive activity (lava flows), thermal springs, and fumaroles. Significant shallow hydrothermal reservoirs would provide initial opportunities for geothermal energy
