SATELLITE BASED OBSERVATIONS OF PRE-EARTHQUAKE TRANSIENT THERMAL ANOMALIES IN IRAN

The realization that Earth’s surface temperature is significantly related to its subsurface processes, has led to the development of an interesting trend of earthquake research. Any abrupt change in near surface temperature in tectonically active regions, detected through thermal remote sensing can provide important clues for impending earthquakes. The paper presents the study of three major past earthquakes (Bam earthquake, 26 Dec. 2003; Dahoeieh-Zarand earthquake, 22 February 2005; and Darb_e_Astaneh earthquake, 31 March 2006) and associated pre-earthquake thermal anomalies of Iran through NOAAAVHRR and TERRA-MODIS data. The analysis of Land Surface Temperature (LST) time series maps generated from AVHRR and MODIS data show development of a distinct thermal anomaly before all the above earthquakes. The intensity of anomaly varies from 5-12 °C and anomalous field develops close to the epicentre area 1-5 days before the earthquakes. The study found that intensity and spatial extent of the anomalous area is directly proportional to the magnitude of earthquake and inversely proportional to focal depth. Further, a similarity in surface displacement field derived from InSAR study and thermal anomaly field has also been observed in case of Bam and Dahoeieh-Zarand earthquakes. The results of this study are an important contribution to the knowledge of earthquake thermal precursor and can be very useful in monitoring the thermal regime of tectonically active regions.

Keywords:

Earthquake , thermal anomalies , land surface temperature , air temperature