Thermal RS for Geologic Applications

1. Thermal RS for Geologic Applications Volcanology, Earthquakes, etc.

5. Geologic Applications of Thermal RS • Two general approaches: • Use differences in emissivity and/or thermal lag of rocks and minerals to map their surface distribution (covered in previous lectures) • Use thermal remote sensing to detect thermal anomalies (kinetic temperature changes) that might be associated with geologic activity (e.g., volcanoes, geothermal areas, earthquakes, etc.)

6. Earthquake precursors • May observe thermal anomalies prior to earthquakes • Controversial – still a subject of debate among researchers. • These have been observed anywhere from several weeks to just before an earthquake releases (but are they related??). • Example: Bhuj earthquake in Gujarat, India (2001) • >20,000 people killed • Some anomalous heating observed prior to quake using AVHRR thermal band (with the benefit of hindsight to look for the anomaly after the quake happened) • Temperature peaked 3 days before quake

8. Earthquake in Bam, Iran • Thermal anomaly peaked 5 days before the quake • Temperature as much as 8 – 10 degrees C higher than normal • Temperature normal again 3 days before quake

10. Volcanology • Volcanic activity includes the movement of magma beneath the surface and eventually onto the surface. Understanding this process is critical for: • Predicting eruptions • Tracking lava flows • Tracking ash plumes • Studying volcanic “plumbing”

11. Chiliques Volcano in Chile Hasn’t erupted in 10,000 yrs but is now showing signs of a potential eruption Bright spots in thermal image show location of magma just under the surface (not visible in optical remotely sensed images).

12. Popocatepetl, Mexico Side by side “chips” show 2 thermal wavelengths on 4 different days Images from ASTER

13. Lava flow in western Russia

14. Ash plume from Mt. Cleveland in the Aleutian Islands Visible MIR/FIR combination FIR FIR Ash Subsurface Magma

15. Geothermal Studies • Can identify geothermal resources using combinations of hyperspectral and thermal RS • Certain mineral associated with geothermal areas can be detected with hyperspectral data • Hot spots can be detected with thermal • Offers tools for finding new geothermal areas that can be used for power generation, etc. • Example: Brady Hot Spring area in Nevada • Thermal data aided in discovery of geothermal area along fault line that was previously unmapped.

17. Other Thermal RS Applications • Archaeology (e.g., finding old roads) • Atmospheric Science • Marine Science • Pollution monitoring • Search and Rescue • Etc., etc.

18. Summary • Thermal remote sensing adds another dimension to our ability to gather information about the earth’s surface • Important to have an ongoing thermal remote sensing program (e.g., Landsat thermal band) in the U.S.