Radar and infrared remote sensing of geothermal features at Pilgrim Springs,Alaska

Radar and thermal data collected by a high-altitude aircraft were used to study thermal anomalies and structural elements of the Pilgrim Springs, Alaska area. The radar data included like- and cross-polarized imagery acquired from perpendicular flight paths. The like-polarized imagery was most effective in delineating significant linears. A large number of linears were detected from the imagery. Many of these linears represent fractures and/or faults (lineaments); some of which may possibly provide conduits for the emergence of hot water at the springs. The lineaments have a wide range in orientation, but significant concentrations are parallel to the trends of the Kigluaik and Kuzitrin faults. Radiometer data and imagery from a thermal scanner were used to study radiant surface temperatures which ranged from 3°–17°C. Thermal anomalies associated with geothermal heat sources were detected on the evening imagery, utilizing density-slicing techniques. A radiant temperature difference of 2°C between surface features was required, before a recognizable signature could be detected. Areas of hot ground were detected in site-specific study, but gentle lateral gradients were not.