A Novel Geophysical Approach to Imaging Sinter Deposits and other Subsurface Geothermal Features Utilizing Ground Penetrating Radar

Abstract

For the first time ground penetrating radar (GPR) has been used to image a range of geothermal features in the shallow subsurface. Preliminary results show GPR was successful in: (1) imaging through sinter deposits, regardless of their silica phase, to a depth greater than 10 meters with decimetre resolution; (2) locating the spatial extent of buried sinters; (3) detecting alteration of sinter deposits; (4) mapping subsurface areas of acidic steam condensate overprinting where there was no evidence at the surface of hot ground; (5) deciphering the subsurface spatial distribution of extinct vents; and (6) distinguishing between meteoric and thermal water in the subsurface. Hand augers and vibracores were used to ground-truth the depth and composition of boundary surfaces evident in the GPR traces. Vibracore was even successful in retrieving intact samples of sinter. This initial foray into utilizing GPR has demonstrated promising results as a non-invasive, cost-effective method for locating buried sinters and other thermal features. The application of this technique is useful for geothermal exploration and detection of potentially hazardous subsidence associated with thermal alteration.