Identification of Geothermal Surface Manifestation Using ASTER Satellite Imagery. Case Study: Nakuru County, Kenya

Abstract

Advancement in spectral resolution, spatial resolution, image processing techniques and the quality of remote sensing satellite imagery have enabled use of satellite data for extensive exploration and characterization of geothermal potential areas. In this research, geothermal alteration minerals and mineral assemblages were studied using ASTER a multispectral instrument at two known geothermal potential areas within Nakuru County. SWIR ASTER data was used to characterize hydrothermal altered zones in the study area. Red- Green-Blue (RGB) band combinations, Band ratios, color composite, Relative Absorption Band Depth and Logical Operator Algorithm processing techniques were applied to extract spectral information of important rocks and hydrothermal alteration minerals in the study area. The techniques were used to enhance geological features by contrasting alteration zones and different lithologies occurring in the study area. Zones with high concentrations of argillic, phyllic, propylitic alteration mineral assemblages were enhanced. The study aimed to demonstrate use of satellite imagery in bring down exploration cost by narrowing down to areas that shows geothermal potential. The current study proved ASTER processing techniques to be a valuable mapping tools for geological reconnaissance of a large area thus providing preliminary lithologic and hydrothermal alterations maps that are accurate as well as time and cost effective.