Hydrothermal Alteration Mapping Using ASTER Image of Arta, Geothermal Area of Djibouti

Abstract

Remote sensing plays an important role in geothermal exploration. It can be applied to recognize hydrothermal alteration, which is the first step in geothermal exploration. The main purpose of this study is to validate the ASTER images efficiency in the mapping of hydrothermal alteration in order to elaborate the image processing to be adequate to Arta which our study area. The perspective of this study is to be able to apply mapping technics and geothermal development. The ASTER L3A which covers the whole study area has been used. The image was correct by using the FLAASH algorithm. The performance of RGB image composite and band ratio (BR) has been evaluated. The RGB image composite on the resultant has highlighted the hydrothermal alterations. The Aster band ratio (BR) 3/2 and 4/3 enabled us to map the spatial distribution of vegetation and Iron oxide respectively in the study area. Principal compound analysis has been used to confirm the alteration mineral. The study area present hydrothermal alteration related to rhyolite intrusion. Results indicate that Aster is able to provide the hydrothermal alteration which plays an important role in geothermal exploration.