Structure of The Oka Ile Ange Geothermal Area, East Flores, East Nusa Tenggara Province, Indonesia from 2D Joint Inversion of Magnetotelluric and Gravity Data Anggie Susilawati (a*,b), Prihandhanu Mukti Pratomo (b), Wahyu Srigutomo (b), Doddy Sutarno (b), Enjang J. Mustopa (b), Kartika Hajar Kirana (a), Eleonora Agustine (a), Imran Hilman Mohammad (a), Yudi Rosandi (a)
a) Geophysics Department, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jl. Raya Bandung Sumedang KM. 21 Sumedang 45363, West Java, Indonesia
*anggie[at]geophys.unpad.ac.id
b) Physics of Earth and Complex Systems, Physics Department, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung, Indonesia
Abstract
Oka Ile Ange area is located in the east of Flores Island, East Nusa Tenggara that is a middle part of Banda Arc. The Oka Ile Ange is one of the geothermal areas under exploration to confirm the proven reserves. In geothermal exploration, magnetotelluric and gravity method widely used to determine the structure of geothermal system. About 110 gravity stations have been conducted around The Oka Ile Ange area and analyzed in conjunction with magnetotelluric data from over 120 MT stations in order to jointly interpret the density and resistivity distribution of the Oka Ile Ange geothermal structure. The joint inversion approach can reduce the number of acceptable models by combining several geophysical methods in a single inversion scheme so that the obtained model can explain all data simultaneously. The 2D resistivity and density models have allowed the identification of the geothermal system in The Oka Ile Ange area. The models confirms the presence of a fault system and a depression zone as the controlling factors of the geothermal system beneath the area which is characterized by an anomalous low resistivity and low density, as the main path for the hot fluids.
