Potential Use of Synthetic Aperture Radar (SAR) Data for Geothermal Exploration
The Synthetic Aperture Radar (SAR) is an active remote sensing technology which operates regardless time and weather condition. The application of SAR technology for geology and geothermal related study is growing rapidly. The successful studies in the Interferometric SAR (InSAR) for recognizing ground surface deformations at geothermal power plant were proved that this technology could contribute significantly to geothermal study. Moreover, detecting structural features at ground surface are also important as a key to predict the fluid paths of a geothermal system. However, the use of backscattering intensity of SAR data for detecting structural features at surface is still limited. The main problem might be originated from the SAR geometric distortion and/or limitation of waveband. Overcoming the problem, we used dual SAR observation modes and applied a technique termed as an automatic extraction of linear feature density from SAR (lifedSAR) to detect and quantify structural features at surface. This technique is aimed to predict to fluid paths of geothermal system around active volcanoes. The left and right looking directions of the SAR sensor provide broad view of the local structural features. In this study, we detected the high structural features which are presented by Linear Feature Density (LFD) agree with the location of surface manifestation of a geothermal system. Therefore, the LFD could be potential parameter to predict the fluid path of a geothermal system. The field geological investigation and data fusion between SAR and hyperspectral data were used to validate lifedSAR result.
Figure 1. Backscattering intensity images of ALOS PALSAR in Ascending (A) and Descending (B) orbits show the surface characteristics of Mt. Merapi in different looking direction.
Figure 2. The total LFD calculated using LifedSAR overlaid on intensity image show the alteration zone (A-Zone) is located in the high LFD values.