THERMAL INFRARED REMOTE SENSING FOR GEOTHERMAL SITE CHARACTERIZATION

Remote sensing imagery has been widely used as an exploration and site characterization tool for both mineral and petroleum economic development as well as environmental assessment. Well-established techniques in multispectral and hyperspectral analysis, coupled with new, state-of-the-art imagery from spaceborne and airborne sensor systems, allows their direct and immediate application to problems in geothermal energy development and assessment. Surface mapping of mineralogy and rock type, vegetation stress, and thermal anomalies can be used in conjunction with structural and subsurface context to provide a more comprehensive picture of known geothermal source regions and can help identify new sources or expand existing fields. We have been working with both airborne and spaceborne multi- and hyperspectral data over two known geothermal fields in Nevada: the Steamboat Springs region just south of Reno and the Brady Hot Springs region, near Desert Peak. To date we have used thermal channels in ASTER and SEBASS instruments to map surface mineralogy related to geothermal activity surface thermal anomalies. Work with ASTER data is being conducted over the Brady Hot Springs region where a thermal anomaly associated with the Brady's fault shows up clearly on raw imagery. At 90m/pixel this spaceborne data can easily identify a thermal feature ~2km in length which has been confirmed in the field with ground temperatures of 94C a few centimeters below the surface. We have worked with SEBASS data in the Steamboat Springs region over an older pit and vent structure where elemental sulfur is exposed in the field, as well as the main Steamboat terrace. Clearly distinguished are a number of silicate deposits with varying compositions. Over the main sinter terrace SEBASS has distinguished younger from older sinter based on the strength of the absorption features. Our analysis shows the hyperspectral SEBASS data have the ability to map lithologies based on subtle spectral variations in mineralogy. These results and synthesis with regional structure and geology will be presented at the meeting.