Revealing Geothermal Potential Areas with Remote Sensing Analysis for Surface Temperature and Lineament Density: Case Study in South Bajawa, NTT, Indonesia

The research area is located in the Southern part of Bajawa, Ngada District, East Nusa Tenggara Province. This area has a geothermal potential and unique geological setting where many cinder cones are extending along NNW-SSE. A geothermal area usually indicated by surface manifestations that reach to the surface through geological structures. The initial stage to find out the existence of a geological structure that represented by surface lineament, and surface manifestations can be identified using satellite imagery to facilitate the exploration process in the field. The relationship between them is important to find out the potential geothermal area. Therefore, this study aims to analyze the relationship between geological lineament density and geothermal manifestations at the southern part of Bajawa based on the integration of ASTER imagery, DEM and Satellite Gravity anomalies. ASTER that consist of Visible-Near Infrared (VNIR), Shortwave Infrared (SWIR), Emissivity, and Surface Kinetic Temperature are used to identify surface geothermal manifestations. DEM imagery is used for lineament density analysis. While the satellite gravity anomalies are used to support the interpretation of geological structure in the study area. Field checking is conducted to ensure the results of images interpretation. The result of imagery analysis shows that geothermal manifestations are distributed at Nage and Mataloko areas indicated by surface kinetic temperature anomalies that reached 37.75C and 37.85C degrees, and rock alteration includes silicate clay minerals and quartz. High-density anomalies (>3km/km2) of geological lineament also located at Nage and Mataloko areas. Also, the analysis of Second Vertical Derivative (SVD) from satellite gravity anomalies shows that low gravity anomalies range from 0 to 0,5 mGal are found in Nage and Mataloko areas indicate the existence of geological structure in this area. The field check shows the same result where there is surface manifestation such as hot springs, fumarole, boiling mud pools, sulfur deposits, and altered rock are found at Mataloko and Nage area. The results of the interpretation of lineament density and the distribution of surface manifestations at the study area concluded that the relationship between the two is linear. © 2020 IOP Publishing Ltd.