Abstract: We collected the thermal infrared remote sensing data of thermal infrared brightness temperature Yutian at the epicenter of M_S6.4 earthquake within a range of about 400 km from April to July in 2020, which is measured by China Geostationary Meteorological satellite FY-2G. The infrared data of the prime time from 1:00 to 5:00 local Beijing time were selected and processed by wavelet transform and power spectrum estimation method. The evolution process of relative power spectrum anomaly before and after the main shock was obtained. The relative power spectrum of the same period in 2019 was compared and analyzed. The possible mechanisms for the time evolution and spatial distribution of the anomalies are discussed. The results show that from the beginning of April 2020, sporadic high-value anomalies appeared in the southern margin of Tarim Basin, with a characteristic period of 13 days; then the anomaly area gradually expanded along the basin edge fault and extended to the southern margin of Altyn Tagh. In the end of April, the anomaly area further expanded and formed an anomaly zone across the seismogenic fault, and the anomaly reached the peak in the end of May and early June 2020.With the approach of the earthquake, the anomaly area began to shrink, and the anomaly amplitude was rapidly reduced in the area near the epicenter area and disappeared impending the main shock. After comparing and analyzing the relative power spectrum values of the same frequency study area in the same period of 2019, it is considered that the thermal infrared brightness temperature anomaly could be a short-term and impending anomaly before the earthquakes.

Key words: the 2020 Yutian M_S6.4 earthquake, Thermal infrared brightness temperature, Anomaly of relative power spectrum