Co-Existing Volcanism and Hydrothermal Activity at Delimutu, Flores Island, Eastern Indonesia

Abstract

A geoscientific survey was carried out over the Sokoria region of Flores Island, East Indonesia to assess its potential for small scale geothermal development for local supply of electricity. The Kelimutu volcanic complex is a classic example of a volcano-hosted hydrothermal system. The complex hosts both an active volcanic component and a high temperature hydrothermal system. Geochemical surveys confirmed that at highest elevations, two of the Kelimutu Lakes contained a magmatic component while the third had characteristics of high elevation steam condensates from the geothermal system. With decreasing elevation, the chemistries of fumaroles and hot springs extending over an area of 80 sq km indicated mixing of both the magmatic and condensate components with neutral chloride outflows. This geochemical model was supported by resistivity data which indicated high temperatures north of the Mutabusa fumarolic area and an outflow along the Lawongalopolo River Valley in the south west of the prospect.