Analysis on thermal infrared anomalous temperature increase of modis satellite before Yutian MS7.3 earthquake

In this study, the continuous thermal infrared data of MODIS/Terra satellite remote sensing of the Yutian MS7.3 earthquake area from January 2014 to February 2014 are collected, and by cloud-removing, the thermal infrared data between 4:00am-6:00am in Beijing time which is the best period for observation to conduct land surface temperature data retrieval, are selected. Time evolution process of land surface temperature anomalies before and after the earthquake is analyzed as well as the relationship between abnormal spatial distribution and active fault. Then, the impact of non-structural factors such as topography of earthquake area, seasonal climate, rain and snow on land surface temperature anomalies is discussed. The result shows that: a) There was phenomenon of thermal infrared abnormal temperature increase appearing near the epicenter area one month before the Yutian earthquake, and there was a certain correspondence between the abnormal temperature increase and earthquake occurrence time. The significant temperature increase happened in the first half of the month, while 5 to 6 days before the earthquake, the abnormal increase reached its peak, and the temperature dropped rapidly after the earthquake. b) Through the relative analysis of non-structural factors such as earthquake area's topography and landform, seasonal weather, rain and snow, the anti-seasonal structural temperature increase signals were discovered, and the rain and snow had a certain degree of influence on the abnormal temperature increase of the earthquake area. c) Due to the complex and sensitive fault structures of the valleys and basins at the southwest of the epicenter, the thermal infrared abnormal temperature increase usually starts from this area and gradually migrates to the epicenter along the faults. d) Abnormal temperature increase zone presents strip distribution which is in consistent with the NE-striking main fault zone. After full consideration of the influence of non-structural factors on the abnormal temperature increase, it was inferred that this thermal infrared temperature increase could be a short-imminent precursor before the earthquake. ©, 2015, Editorial Office of Seismology and Geology. All right reserved.