Tompaso Geothermal Field is located in Minahasa. Based on the Decree of the Minister of Mines and Energy No. 560 K/30/M.PE/1987 dated July 20, 1987, Tompaso Geothermal Field is part of the Lahendong – Tompaso Geothermal Working Area (Wilayah Kerja Panas Bumi – WKP). Tompaso Geothermal Field is located approximately 15 km south of the Lahendong Geothermal Field.
Lithology of Tompaso Geothermal Field consists of tuff, rhyolite, andesite, pitchstone, pyroclastic breccias and pumice. Geological structures in Tompaso are Soputan Fault trending northeast – southeast and Tempang Fault trending north – south. Other structures such as lineaments trending relative to the north are also found in this area.
Geothermal manifestations in Tompaso are steaming grounds, fumaroles, hot springs, mud pools, and warm springs. In this area, exploration and exploitation drillings have been conducted since October 2008. Power generation with the capacity of 2×20 MW within Geothermal Power Unit 5 and Unit 6 is being built on the Tompaso field and are expected to be operated immediately.