Study On Theactivity Of Faults By Using Of Infrared Remote Sensing Data

The thermal infrared remote sensing detected the surface thermal conditions bymeasuring thermal infrared radiation of earth-atmosphere system. With the in-depthstudy of satellite remote sensing technology in terms of earthquake precursor, a largenumber of infrared images showed that the variation of active faults and infraredradiation anomalies are closely related. The activity of faults was the geologicalcarrier of anomaly and earthquake, and the study on its temperature field informationwas a new way to detect the tectonic activity of faults. In the study of fault activityby using infrared remote sensing, the thermal information which related to faultactivity was rarely part of the observation information, and we need to eliminatesome interferential factors such as atmospheric conditions and topography.In this paper, we used the infrared brightness temperature data of FY-2C/2E as datasources, and took the southeast of Gansu and neighboring areas as the study area. Byusing the wavelet analysis method, we studied in detail the relationship between thefaults and thermal infrared data, speculated the strengthen distribution of faultactivity in the study area, and tracked this region effectively. Using the relativepower spectrum method, combined with a vertical cross-section data, we analyzedthe typical temporal and spatial evolution of the brightness temperature, and formeda better thermal infrared analysis process. We got the following conclusions.1. The infrared brightness temperature data in the study area could better reflectthe distribution and activity level of faults, which provided some indication toextract fault thermal information. The wavelet analysis method was suitable forextracting and recognizing the thermal radiation changes in the strength and theoverall level of seismic hazard, and could clearly show some secondary faults andburied faults. The width of heat strip in the chart of fault vertical cross section wasabout20Km, which was the affecting width of the infrared brightness temperature,rather than the true width of faults.2. The main faults in the study area had obvious brightness temperature distribution in space. Overall, the block edge was higher, and the internal low. Thismay be because the block edge was under pressure, which reflected the changes ofthe characteristics in the stress field. In the study area, the western part of north edgefault in West Qinling had the largest intensity.3. By combing the wavelet analysis method and the relative power spectrummethod, we initially proposed the seismic infrared anomaly information extractionprocess. After the study of three earthquake cases in the three typical structureregions (which were Wenchuan, Yushu and Minxian-Zhangxian), we found thefollowing conclusions.(1) The seismogenic faults of these earthquakes were clearly shown in the chartof fault vertical cross section. The position of heat strip for Minxian-Zhangxianearthquake showed that the earthquake rupture was probably a buried fault whichwas10-20Km away from the Lintan-Tanchang fault.(2) There were obvious infrared abnormality characteristic periods before andafter the earthquakes. Due to the different geological environment, three earthquakeshad different infrared abnormality characteristic periods.(3) Earthquake thermal infrared anomalies were associated with theconstruction significantly. The zonal distribution of images, which had a relationshipwith the tectonic activity, had occurred in the spatial and temporal distributionpicture of earthquakes, and the epicenter was located in the thermal anomaly strip.(4) The infrared anomaly duration of each earthquake was about six months, theabnormal area had no apparent relationship with the earthquake magnitude, and theevolution of thermal anomaly was shown as the appear-strengthen-shrink-disappearprocess. Meanwhile, the closer to the earthquake origin time, the clearer the thermalanomaly. This may be because of the accumulation of stress and the changes ofunderground greenhouse gases and atmospheric temperature.Compared with the previous work, this paper first gave the spatial and temporaldynamic distribution of active faults, which help to improve the accuracy of theearthquake prediction. But for the control factors of fault thermal radiation anomalyand the reliability of the buried faults, we did not have a deep study, which was the key to the future research.