| A number of mathematical processing methods for the data of the electric and magnetic fields observed on the ground and the electric field data observed in the ionosphere have been developed, and then, the maximum entropy spectra estimation method (MEM) and the statistic methods for the frequency and energy of electromagnetic (EM) field impulses are selected to process the electric and magnetic field observation data, with the ultimate purpose of identifying information associated with earthquakes (EQs). The geo-electric field and geo-magnetic field observation data minutely observed at five geo-electric field stations and two geo-magnetic field stations around the epicenter of the Ms8.0Wenchuan earthquake (EQ) of2008have been processed using the methods, and ground electric and magnetic field changes corresponding to the Wenchuan EQ, and the Ms7.3Yutian EQ of2008occurred in Xinjiang as well as some Ms6.0EQs occurred in the Qinghai-Tibet plateau have been in detail studied. Furthermore, the electric field data in the ionosphere observed through the DEMETER satellite of French, which sampling rate is39.0625Hz, in the range of2000km over the Wenchuan area have been downloaded and processed. The space data include498successive orbits from January to June,2008, and the two groups of repeated-visit orbits with16-day repeated-visit period that are consisted of179orbits from January2006to December2009. Besides, the space data include the electric field data of the ionosphere observed along one group of long-distance orbits with the longitude difference of180°from the Wenchuan area, which are consisted of91repeated-visit orbits within of the range of2000km from January2006to December2009. Then, electric changes of the ionosphere corresponding to the Wenchuan and Yutian EQs as well as some of the Ms6.0EQs occurred in the Qinghai-Tibet plateau have been studied. Therefore, some significant understandings are obtained as follows:1. In the observation of the geo-electric and geo-magnetic fields on the ground, the significant anomalies of the geo-electric and geo-magnetic fields, which included the self-potential changes, the increased power spectrum density (PSD) of the geo-electric field (increased by one to three orders of magnitude in PSD amplitude) and the waveform distorition of the geo-magnetic field diurnal variation were recorded preceding the Ms8.0Wenchuan and Ms7.3Yutian EQs,2008.2. In the observation of the electric field of the ionosphere through the DEMETER, the space EM phenomena, such as the increases of the PSD, energy and frequency, of the extremely low frequency electric field (frequencies were lower than20Hz), appeared prominently preceding the Wenchuan EQ and the Yutian EQ as well as some of the EQs with magnitude of Ms6occurred in the Qinghai-Tibet plateau.3. The increases of the electric field PSD of the ionosphere well corresponded to these of the ground electric field before the Wenchuan and Yutian EQs. The correspondence between the changes of the ground electric field and these of the ionosphere electric field before the great EQs are the typical EQ examples of the space-ground integration electromagnetic phenomena. This could be an innovation of research results in the seismo-electromagnetic field.4. Possible generation causes for changes of the earthquake-related electric and magnetic fields are preliminarily explained, along with the spatial-temporal inhomogeneous distributions of the ground EM precursory phenomena. The mechanism for electric field changes of the ionosphere is tried to explain.The research results of this thesis has preliminary revealed that in the observation of the electric of the ionosphere, the low-frequency EM radiation phenomena can be recorded in the imminent period before the great and strong EQs, and that through the space-ground integration EM observations, the technological levels for EQ prediction can be further raised. Besides, it is recognized that the spatial distribution and amplitude of the space electric field anomalies before EQs are quite complicated. An EQ electromagnetic satellite will be launched in china, therefore, the research results of this thesis have some practical significance for the design of the electric technical parameter of the satellite loading, the running orbit and the using of space field observation data. |
