Geomorphic Indices Characterization Related to Geothermal Manifestation Appearance in Cubadak Area, Pasaman Regency, West Sumatra Province

Indonesia has 351 spots of geothermal potential area with installed electric power is about 8.9% of total energy. Sumatra Island has 101 geothermal potential spots with energy total is 9,679 MW. One of potential areas in Sumatra Island is located in Cubadak Geothermal Area, Pasaman Regency, West Sumatra Province which indicated by surface manifestation of hot springs and have 70 MWe estimated potential (Ditjen EBTKE, 2017). This research aimed to determine the correlation between geomorphic indices to thedistribution of surface geothermal manifestation. The research method analyzed the geological lineament and calculate geomorphic indices through SRTM- DEM image and SHP data; lineament density(Ld), mount-front sinuosity (Smf), bifurcation ratio (Rb), valley floor width – valley height ratio (Vf) and drainage density (Dd).Geological lineament that interpreted as geological structure has main pattern northwest - southeast (NW - SE) orientation. The calculation of geomorphic indices results Ld value; 0.000 – 1.501 Km-1 (low – high), Smf value; 1.0 – 3.2 (moderate – active tectonic), Vf value; 0.14 – 0.47 (high uplift tectonic), Rb value in general; 3.26 – 4.56 (not deformed area), and formed rough – very fine landform texture of Dd value; 2.58 – 7.29 Km-1 , related to surface manifestation distribution; AR1 group on A6 and A15 sub-watershed,AR2 on A15 s