Affiliation:
1. Physics Department, Faculty of Mathematics, Universitas Brawijaya, Veteran Street, Malang 65145, Indonesia
2. Brawijaya Volcano and Geothermal Research Center, Universitas Brawijaya, Veteran Street, Malang 65145, Indonesia
Abstract
As per the Geothermal Potential Book published by the Ministry of Energy and Mineral Resources (MEMR) in 2017, Pacitan Regency in East Java Province, Indonesia, has the potential for geothermal energy. Two hot spring manifestations, namely, Karangrejo and Tinatar, located in the Arjosari and Punung districts of Pacitan Regency, respectively, have a combined resource of 25 MWe. We acquired ground-gravity data and evaluated gravity anomalies to explore the underlying geological structure in order to understand the geothermal system behind these manifestations. The results of the study show that the gravitational anomaly in the Karangrejo-Tinatar region ranges from 163 to 176 mGal. Additional analysis of the complete Bouguer anomaly (CBA) map, first horizontal derivative (FHD) map, and field observations points to the existence of three NW-SE trending faults. Two of the faults, which are the Karangrejo fault and the Tinatar fault, may be the flow paths for the manifestation of Karangrejo and Tinatar hot springs.