Application Of High-Resolution Thermal Infrared Sensors For Geothermal Exploration At The Salton Sea, California

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Conference Proceedings: Application Of High-Resolution Thermal Infrared Sensors For Geothermal Exploration At The Salton Sea, California

Abstract
The Salton Sea geothermal field straddles the southeast margin of the Salton Sea in California, USA. This field includes approximately 20km2 of mud volcanoes and mud pots and centered on the Mullet Island thermal anomaly. The area has been previously exploited for geothermal power; there are currently seven power plants in the area that produce 1000 MW. The field itself is relatively un-vegetated, which provides for unfettered detection of the surface mineralogy, radiant heat, and emitted gases using air and spaceborne thermal infrared (TIR) sensors. On March 26, 2009, the airborne Spatially Enhanced Broadband Array Spectrograph System (SEBASS) sensor was flown over the Salton Sea-Mullet Island area. SEBASS has a spectral resolution of 128 bands in the 7.5-14.5 micron spectral region and a spatial resolution of 1m/pixel from the 3000-ft altitude flown for this study. A large portion of the Calipatria Fault, a NW/SE-trending geothermally active fault that bisects the Mullet Island thermal anomaly, was imaged during this flight and several thermal/mineralogical anomalies were noted. The orbital Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) has only 5 spectral bands at 90m/pixel resolution, but has acquired dozens of visible and TIR datasets over the geothermal field in the 10-year history of the instrument. The thermal-temporal trend of this dataset has been analyzed, and the November 2008 image studied in detail for comparison to SEBASS. The land-leaving TIR radiance data were separated into brightness temperature and surface emissivity. TIR emissivity data are unique to each mineral and a TIR mineral spectral library was used to determine their presence on the ground. Various mineral maps were created showing the distribution surrounding the most active geothermal features. The higher spectral/spatial resolution SEBASS data were used to validate the lower spectral/spatial resolution ASTER data (as well as the higher resolution laboratory TIR data of collected samples). Forward looking infrared (FLIR) data were also obtained in the field to better understand the temperature distribution and flux in order to verify an accurate surface temperature and capture degassing. By using this approach of progressively higher spatial and spectral resolution sensors, temperature and mineral anomalies commonly associated with geothermal activity were more easily detected. This approach enables an innovative exploration methodology for future exploration of new geothermal locations using TIR remote sensing.

Authors 
K. A. Reath, M. Ramsey and D. M. Tratt








Published 
Publisher Not Provided, 2010





DOI 
Not Provided
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Citation

K. A. Reath,M. Ramsey,D. M. Tratt. 2010. Application Of High-Resolution Thermal Infrared Sensors For Geothermal Exploration At The Salton Sea, California. Proceedings of (!) ; (!) : .