Remote sensing observations of pre-earthquake thermal anomalies in Iran

Stresses acting before an earthquake in tectonically active regions can augment the near ground temperature of the region. Such changes detected through thermal remote sensing can provide important clues about future earthquakes. A post-earthquake analysis through NOAA-AVHRR data showed pre-earthquake thermal anomalies prior to the Bam earthquake on 26 December 2003 and the Dahoeieh-Zarand earthquake on 21 February 2005 in Iran. It was observed in these earthquakes that there was short-term temporal increase in land surface temperature (LST) of the regions around the epicenters. The rise in temperature was about 5-10°C. Further, temperature variation curves prepared from air temperature data collected from several meteorological stations around epicentres confirmed the appearance of thermal anomalies prior to several earthquakes between February and March 2005 in Iran. The thermal anomalies went away along with the earthquake events. Release of greenhouse gases from rocks due to the induced pressure before earthquakes can create a localized greenhouse effect. Charge carriers in rocks can be free electrons, which dissociate under high pressure. When they again recombine to attain electron stability they release heat, which can increase the LST of the region.