Thermal Infrared Remote Sensing Information Extraction Of Active Fault And Preliminary Application

Earthquake is a special form of crustal movement,a performance of sudden fault dislocation,and an evidence of tectonic seismic activity existence,resulting in the great significance of monitoring development and activity of active faults.It is known that near-surface temperature anomalies appears before the earthquake,and in recent years,using thermal infrared radiation satellite to monitor tectonic activities and thermal radiation anomalies induced by seismic activities,has been a prospective technique with wide application.This paper chooses optical image,including MSS,TM,ETM,and thermal infrared brightness temperature image,including EOS/MODIS,NOAA/AVHRR,as experiment data.And then extracts macro and micro geomorphological features of fault development,and makes interpretation and determination for locations and status of active faults in Tianjin study area,on the basis of previous researches.The active faults interpreted in this paper consist of faults in Tijian and adjacent areas,Changping-Fengnan break,Lixian-Shangcang fault,Fengtai-Yejituo fault,Jiyunhe fault and Tangshan fault.The interpretation shows that:(1)the acquisition time of MSS image is close to time of Tangshan earthquake,and interpretation result is good for obvious linear fault track in image;TM/ETM has abundant color,and obvious fault track is observed through principal component analysis and filter.(2)the area is with rich water,and significant effect can be extracted from infrared brightness temperature image,which fits well with fault location derived from optical image.Satellite infrared brightness temperature is the combination of thermal radiation of surface and atmosphere,and influenced by non-structural factors,like topography,land cover type and meteorology.Therefore,to remove non-structural factors is the premise of determining abnormal signal.This paper chooses Daliangshan-Longmenshan fault as study area in Sichuan-Yunnan province,calculates infrared brightness temperature background field based on NOAA/AVHRR thermal infrared brightness temperature data,and analyses the spatial-temporal variation feature and law of thermal infrared brightness temperature field in study area,which lay the foundation for digging abnormal signal associated with seismotectonics.Based on analysis of brightness temperature dynamic background field,this paper designs algorithm of detection and extraction on the basis of wavelet transform,and analyses the feasibility of the algorithm for extracting thermal infrared anomalies before earthquake through two examples.The result shows:(1)the algorithm of extracting anomalies based on statistic rule can smooth the non-structural factor information to a certain extent,but cannot get good result in area suffering from rain and cloud.(2)the algorithm of extracting anomalies based on wavelet transform is good at removing lowfrequency background information and high-frequency noise,and extracting the band containing possible seismic thermal signal from thermal signal.