SUBSURFACE CHARACTERIZATION OF THE MOUNT TALANG GEOTHERMAL SYSTEM USING GRAVITY AND THERMAL REMOTE SENSING

Abstract

Mount Talang is one of the active volcanic geothermal systems in West Sumatra, Indonesia, where reliable subsurface characterization is essential to reduce exploration uncertainty and improve resource assessment. This study integrates satellite gravity and thermal remote sensing to investigate the geothermal system. Complete Bouguer Anomaly (CBA) was calculated from gravity disturbance data derived from GGMplus and Full-Scale Topographic Gravity (FSTG) from SRTM2gravity, followed by regional-residual separation using a 2000 m upward continuation. Two-dimensional gravity modeling was integrated with a single Landsat-8 OLI/TIRS-derived Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) analyses. The CBA (−38 to −10 mGal) and residual anomalies (−8 to 0 mGal) depict a low-density zone associated with hydrothermally altered and fractured volcanic rocks. The model indicates a shallow alteration zone (2.30 g/cm³) beneath the Bukik Gadang and Bukik Pincuran Tujuh hot springs and an intrusive body that may represent a potential heat source. The elevated LST (11–34°C) associated with low NDVI spatially coincides with known geothermal manifestations. The integrated results provide a useful reconnaissance approach for identifying potential geothermal structures and guiding further geophysical and geochemical investigations.