| Remote sensing is widely utilized in geosciences. Thermal infrared images have been used to predict earthquakes since 1990. However, thermal infrared anomaly is not yet a reliable, stable and testable evidence for predicting earthquakes because earthquake prediction is a difficult issue in the world, as well as the complexity of remote sensing itself still exists. On one side, the infrared anomalies reported are not accepted generally owing to lack of reliable verification. On the other side, its mechanism is not clear. In fact, tectonic activities are results from crustal motion. And it is accepted generally that earthquakes are generated by fast motions along faults. Current tectonic activity is a geological tie between anomalies and earthquakes, and is a key to answer the problem. Therefore, shift of research focus from seeking seismic precursors to monitoring processes of fault activity can provide definite physical evidence for the earthquake prediction and is more significant.It is a new approach to use remote sensing technology to detect the current tectonic activity, which faces many new difficulties. In this thesis, studies of five aspects on current tectonic activity are made by quantitative and physical methods, based on thermal infrared remote sensing data. First, land surface thermal infrared radiation is extracted by the quantitative remote sensing method. Second, influence of non-tectonic factors is analyzed with the wavelet method. Third, space effect on the current tectonic activity is extruded from the thermal radiation field of land surface by the difference between influence of atmosphere and tectonic activity on land surface. Fourth, the Heat Penetrability Index (HPI) method is applied to get the underground thermal information. At last, information on tectonic activity extracted from thermal infrared radiation is compared with that of other methods.The new contributions of this thesis are summarized as follows:(1)Land surface brightness temperature (LSBT), which is an important parameter for studying earthquakes and presents thermal infrared radiation(TIR) of land surface, is extracted by the split-window method. LSBT is the temperature of black body with the same irradiance of land surface. Although LSBT and temperature have the same dimension, LSBT is representative of thermal radiation energy, but not temperature. The remote sensing data are reformed by interference of the atmosphere. The first task for extracting information of tectonic activity is to remove interference for acquisition of useful information is. LSBT is chosen as an inverse target. Not only emissivity of land surface is avoided, but also atmosphere correction is realized. This is more practically significant for studying earthqaukes. LSBT in the mainland of China is obtained from NOAA/AVHRR data from 1981 to 2001 by split-window method. The result shows that atmosphere influence on LSBT from land surface to satellite-based sensor is about±10K.(2)Using the wavelet method, influence of non-tectonic factors is analyzed, and annual variation field and the low frequency band of LSBT are extracted. Thermal infrared radiation of land surface bears on many factors such as tectonic activity, atmosphere, solar radiation, plant and so on. Not all thermal infrared anomalies are attributed to earthquakes. How to exclude the non-tectonic information is the second problem for studying tectonic activities or earthquakes with TIR. The influence factors of thermal radiation of land surface are studied by the wavelet analyses based on frequency difference between tectonic and non-tectonic factors. Stable annual variation...
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