INTEGRATING LANDSAT-8, EMAG2V3, AND GGMPLUS GRAVITY DATA FOR GEOTHERMAL PROSPECT ZONATION AT DORMANT VOLCANO (CASE: MOUNT PUSUK BUHIT, NORTH SUMATRA, INDONESIA)

Rina Dwi INDRIANA , Ihya Qothrunnada RAHMANI , Agus SETYAWAN , Ahmad Ali MUCKHAROM , Richard LEWERISSA

DOI: 10.21163/GT_2026.213.05

ABSTRACT: Indonesia has an estimated 23,591.75 MWe of geothermal potential, but exploration is costly and time-consuming. One of the islands in Indonesia, namely Sumatra, has 104 geothermal prospects, including the Simbolon–Samosir area, where Mount Pusuk Buhit has 150 MWe of inferred resources. This study uses satellite imaging to map surface and subsurface features at Mount Pusuk Buhit. Landsat-8 imagery is processed to create visualisations, while GGMPlus gravity data are analysed to map the land's structure. The NDVI calculation results are -0.51 to 0.87. The NDVI at the hot spring is lower than its surroundings, at -0.51 to 0.17. The research area has an LST of 19.72°C to 36.04°C. LST maps reveal localised heat anomalies on the flanks and foothills of Pusuk Buhit, some coinciding with known geothermal manifestations. Low NDVI values in these areas indicate reduced vegetation cover. Negative gravity anomalies are interpreted as fractured or fluid-influenced low-density zones, and positive anomalies indicate dense volcanic or intrusive bodies that may act as structural boundaries. Integrated LST and gravity overlay identifies four prospect zones. High LST coinciding with negative gravity is the most favourable for upflow. The Curie Depth Point values are generally around 28 to 31 km, which correlates well with heat flow values of around 48 to 50 mW/m². The results demonstrate the effectiveness and cost-effectiveness of combining Landsat-8 thermal, EMAG2V3, and GGMPlus gravity anomalies in assessing geothermal potential in volcanic terrains. The workflow can be used for other geothermal prospects in Indonesia.

Keywords: Landsat-8, EMAG2V3, GGMPlus, geothermal, dormant, volcano, Pusuk Buhit.

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