CAN YOU USE SPACEBORNE THERMAL INFRARED SENSORS TO PREDICT EARTHQUAKES?

There have been many studies using remote sensing in structural geology, but this study is unique in its focus. There is a theory that earthquakes have a thermal anomaly associated with their location prior to the event (Tronin, 2000). Others disagree (Bhardwaj et al., 2017). However, to date, there has been no test of this via satellite archives. Detection of thermal energy of earthquakes prior to slip would have major social implications for hazard mitigation. The expectation of this study is that there will be no detectable connection between earthquakes and thermal anomalies.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data archive (Jan. 1, 2000 – Feb. 20, 2017) from Earth Explorer (http://earthexplorer.usgs.gov) was used for temperature measurements. ASTER was chosen because it measures temperature in 90 m pixels, small enough for anomalies to be a significant portion of a pixel. A total of 3,010,036 footprints averaging 177,061 per year were found. Metadata were used to create shapefiles for these footprints, and all metadata fields were associated with the polygons as attributes. Footprints crossing the ±180 longitude cause issues with direction, so they were removed from this particular study.

Worldwide earthquake data, for magnitudes 4.5+, were collected from the USGS earthquake search catalog (http://earthquake.usgs.gov) from the same period. There are a total of 122,604 earthquakes, averaging 7,212 per year. Earthquake data were obtained as CSV files, imported as XY-data into the GIS program ArcMap, and given a Z value for depth. ArcMap was used to limit earthquakes to sub-aerial locations, as water would disperse a thermal anomaly’s signal.

To be useful for hazard management, a thermal anomaly should be detectable at least a week prior to an event, and rise sufficiently above the average temperature for that time and location. ASTER data from other years were used to determine this average – future studies will use temperatures within the ASTER scene itself. Earthquakes that didn’t have at least four footprints within a two week window centered on the event were also removed. This study will determine if a thermal anomaly is detected in any earthquake remaining, and if this is an accurate method for future use.