Outgoing longwave radiation changes of the Ms6.0 Luxian earthquake based on tidal generating force

With the rapid development of society, the overlapping degree between the distribution of social economy and population and the impact range of earthquake disasters is gradually increasing, and the harmfulness of earthquake disasters is further highlighted. Strengthening the monitoring and prediction of earthquake disaster risk is an important means to reduce the risk of earthquake disasters. Infrared remote sensing has gradually become an important means of earthquake prediction and monitoring. On September 16, 2021, a Ms6.0 earthquake occurred in Luxian, Sichuan Province. The FY-2H surface Outgoing Longwave Radiation (OLR) data product was used to analyze the anomalous distribution and changes of OLR in the study area from August 27 to October1. On the basis of the TFFA algorithm, our research extracted infrared radiation anomaly and made a retrospective attempt at short-term and imminent earthquake monitoring and prediction. We extracted the infrared radiation anomaly that is continuous and has remarkable change characteristics one week before the earthquake and identified the development and evolution of the impending earthquake infrared anomaly. Results showed a cross distribution between anomaly distribution and seismic structure, and the evolution process corresponds to the thermal infrared radiation law of rock fracture. In accordance with the extracted long-wave radiation anomaly, we speculate that only when the tectonic stress accumulates to the critical state of rock fracture and sliding can the tidal force trigger the earthquake, and the extracted anomaly is likely a manifestation of energy release in this process. With the change of tidal force, anomalies first appeared in the central and northeastern parts of the epicenter in the study area, and the anomalies were distributed in the northwest-southeast as a whole. This phenomenon and the evolution characteristics of rock stress-strain-fracture-experienced microfracture-fracture-accelerated fracture-fracture process are consistent. Results show that the tidal force of celestial bodies has an induced effect on the earthquake, and the anomaly of long-wave radiation may be the radiation characterization of stress and strain in the process of earthquake incubation. During extraction of seismic radiation anomaly, the selection of background day has a decisive influence on the results. This case study belongs to retrospective analysis; thus, in this study, the type of seismogenic fault is determined by the focal mechanism after the earthquake, and then the background date is determined. If this method is used for anomaly monitoring and prediction before earthquakes, the fault database can be obtained to judge the fault properties of the study area, and the background date can be selected in accordance with the fault properties. Afterward, the abnormal period (September 11-17) was tracked and verified by using NOAA satellite OLR product data; the characteristics of the two results were relatively consistent, which further demonstrated that the FY-2H satellite OLR data can be better applied to seismic anomaly monitoring. Moreover, the FY-2H single point time OLR data product has a good effect on monitoring the thermal anomaly, which further reflects the feasibility of the domestic satellite to conduct short-term and imminent earthquake prediction research. It provides a good application case for promoting the operational application of domestic satellite seismic monitoring and prediction. © 2024 Science Press. All rights reserved.