Seismic thermal anomalies have attracted increasing attention from the scientific community since they were proposed in the mid-1980s. A long-term Outgoing Longwave Radiation (OLR) data set from 2007 to 2016 was used to analyze thermal anomalies in the magnitude 6.7 earthquake that hit Wuqia, China, on October 5, 2008. To identify the earth-atmosphere system’s multiple parameter variations related to earthquakes, other surface and atmospheric multi-parameter data were processed over the critical region of Thermal Infrared Radiation (TIR) anomalies.Nighttime NOAA OLR data were selected because capturing seismic anomalies at night is easier than in the daytime considering the effect of artificial anomalies and solar radiation. The vorticity method was used in this study. To reliably detect seismic precursory information, 2009—2011 data on the absence of significant seismic activity in the Xinjiang region were calculated as background field. Apart from vorticity spatial analysis, time series analysis was utilized in this study. Then, the coupling variation of multi-parameter data was analyzed according to the Deviation-Time-Space (DTS) method.The 10-day average OLR vorticity analysis shows a sudden increase of OLR in mid-September 2008. Moreover, a long-term OLR data analysis showed that the anomalies existed prior to the seismic case only, which can be considered a unique variation. The OLR anomalies were not observed in aseismic years, thereby showing that OLR anomalies were related to the Wuqia earthquake. The OLR anomaly is located on the boundary of the Tarim active block. Therefore, distinguishing the seismic precursor is important. The strong-body earthquake-generating model indicates that the irregular boundary of a solid block is likely to accumulate stress. The Tarim tectonic block has been stable since the Cenozoic era and can be classified as a solid body. Previous studies have shown a strong correlation between stress changes and TIR. The enhanced TIR between the active blocks was due to non-continuous stresses and high energy accumulation induced by the interaction of the active blocks and the strong differential movement between them.The increasing TIR anomalies prior to the earthquake led to heat accumulation on the near-surface and the near-ground air, resulting in the variation of skin temperature, air temperature at the lower height pressure levels, and relative humidity of air. The behavior indicates the coupling relationship between the lithosphere and the atmosphere in the seismogenic region.We deduce that air pressure is one of the external trigger factors of earthquakes. The dramatic variation of air pressure during the seismogenic process might affect the critical state. As soon as all internal conditions (the active seismic structure, the nature of the seismogenic zone, the crustal stress environment, and the focal mechanism) exist, some external conditions may trigger an earthquake.The increase in CO degasing in this case is only at the 800 hPa pressure level, thereby indicating that the source of CO variation is mainly the near-ground surface over the seismogenic zone and appears four days after the shock. The post-seismic variation might be related to the nature of seismogenic structure (locked and extrusion pressure-controlled) and the aftershocks.The surface and atmosphere multi-parameter variations associated with the 2008 M6.7 Wuqia earthquake were analyzed to detect precursor information related to the earth-atmosphere system. OLR anomalies were detected on the boundary of the Tarim active block because stress easily accumulated along a solid block boundary. The enhanced TIR emissions are reflected in anomalous OLR data. Results showed that the spatial location of OLR anomalies could reflect the crustal stress accumulation. Furthermore, OLR, skin temperature, air temperature, and relative humidity showed quasi-synchronous variations before this case. Results supported the seismic multi-sphere coupling model. The multi-parameter coupling between the surface and the atmosphere is an important precursor indicator in the short-term and immediate periods, and should be considered in future seismic infrared monitoring.

outgoing longwave radiation;lithosphere-atmosphere coupling;multiple parameters;earthquake monitoring;satellite observation