Thermal infrared variation associated with strong earthquakes in Xinjiang using satellite data

NOAA outgoing longwave radiation (OLR) data associated with five earthquakes (M > 6.0) in the Xinjiang area of China between 2008 and 2014 were analyzed in this research. The results of spatio-temporal analysis demonstrated that three events showed significant thermal anomalies. The focal mechanisms of three cases were of the thrust type (Wuqia M6.7 earthquake on 5 October, 2008) and of the strike-slip type (Yutian M7.3 earthquake on 12 February, 2014 and the Xinyuan-hejing M6.6 earthquake on 29 June, 2012). The focal mechanisms of the other two cases were the normal fault type. In particular, OLR anomalies associated with the Wuqia earthquake, a thrust type event, were more obvious, and it was consistent with the inverse fault mainly affected by extrusion pressure, which was beneficial to the formation of a thermal precursor. This result was consistent with the experimental results of rock mechanics. In addition, OLR anomalies related to the three cases were all found on the boundary of the Tarim active block, which indicated that stress was more easily accumulated on solid block boundaries.