Wavelet Analysis of Thermal Infrared Radiation of Land Surface and Its Implication in the Study of Current Tectonic Activities

Abstract

Thermal infrared radiation (TIR) of land surface is influenced by many factors such as tectonic activity, atmosphere, solar radiation, plant and so on. How to exclude the non-tectonic information is a key problem before TIR is applied to study tectonic activities or earthquakes. As for the frequency domain, TIR includes mainly 3 frequency bands: (1) high frequency band with period less than 1 year, which is related with weather; (2) medium frequency band with predominant period 1 year, related to the sun, plant and seasons; and (3) low frequency band with period more than 1 year, related to the crustal activity and long period variations of atmosphere temperature. In this paper, TIR is decomposed into 3 exclusive frequency bands mentioned above by the wavelet method. Compared with weather data and earthquake activity, our result shows that thermal anomalies of low frequency component of TIR are resulted most possibly from fault activities and could offer a certain indictor for judging current tectonic activities or earthquakes. The high temperature anomaly areas (or belt) of low frequency component of TIR are likely attributed to the current tectonic activity and earthquakes.