Geothermal Surface Manifestation Characterization Using Airborne Lidar Return Intensity

Abstract

Laser return intensity (LRI) holds excellent opportunity in helping to map lithology and discriminating rock units based on their reflectivity. To date, many rock types have been examined under controlled environment using terrestrial lidar-scanning system (TLS). However, utilization of LRI for detection of rocks properties in a geothermal environment still has received less attention especially from airborne lidar-scanning systems (ALS). This study proposes a novel approach to map and characterize geothermal surface manifestations (GSM) using airborne lidar return intensity. We use an airborne lidar dataset acquired by a Leica ALS70 above the geothermal field near Bajawa, Flores, Indonesia. The effects of scan angle and atmosphere on the resulting LRI images were investigated and where possible corrected for optimizing the positional and spectral information. Characterization of GSM signatures based on altered volcanic rock reflectivity through LRI were validated by the ground truth observation and airborne thermal infrared imagery in Wawomuda, Gou, and Mataloko. We will present an overview of the data corrections needed and preliminary results on the suitability of lidar return intensity values for detecting geothermal surface manifestations in the case of an Indonesian system.