Research On Earthquake Precursor Schumann Resonance Anomaly Observation Method

There must be some physical phenomena observed during the preparation process of tremendous energy before the earthquake outbreaks. Therefore, earthquake can be predicted. But the earthquake preparation process generally takes a long time. It is really a complicated process with a lot of factors involved. Short-term and impending earthquake prediction is a difficult problem with attracts the worldwide scholars exploring for centries. In recent years, some scholars claim that monitoring electromagnetic earthquake precursor is likely to be breakthrough in the field of impending earthquake prediction. Especially, the Schumann resonance abnormal before large earthquakes discovered by Japanese scholars provides a new idea of seismic monitoring. However, Japanese ground-based Schumann Resonance observatories are seriously impacted by the man-made noise which makes it difficult to locat the"abnormal source". It is assumed that Schumann Resonance in the earth-ionosphere cavity must disturb the lower ionosphere. Under this assumption a new Schumann Resonance earthquake precursor monitoring method based on ionospheric nonlinearity is researched in this thesis. High frequency electromagnetic waves along with abnormal Schumann Resonance under their nonlinear modulation at the bottom of ionosphere is demodulated on ground to do earthquake precursor monitoring. A new possible impending earthquake prediction method is found. The main work of this thesis is summarized as follows:(1) A new Schumann Resonance earthquake precursor monitoring method based on ionospheric nonlinearity by Schumann Resonance is proposed and researched.First, the general development of the worldwide earthquake electromagnetic monitoring is studied. The recent research on the relation between natural resonance and seisms is introduced. It appears that a new epoch of earthquake monitoring in frequency-domain starts. And the new Schumann Resonance earthquake precursor monitoring method based on ionospheric nonlinearity is proposed. This method overcomes the difficulty that earthquake abnormal and other interferences can not distinguished in time-domain. The ELF artificial interferences can be reduced. It is a new large-scale seismic monitoring method which can reveal the multi-layers coupling mechanism caused by seism and make it possible to locate abnormal source.(2) Multi-interaction ionospheric cross modulation theory is researched Multi-interaction ionospheric cross modulation theory is researched on the basis of that of Gurevich. In that theory, modulation depth variation due to the electromagnetic wawe phase changes in the multi-interaction condition is not considered. In this thesis, it is analyzed in both the isotropic and anisotropic plasma conditions. The result shows that the modulation depth in the isotropic condition is consistent with that in anisotropic plasma. The conclusion lays the foundation for the nonlinearity interaction of high frequency waves with Schumann Resonance in the lower ionosphere.(3) Multi-interaction HF-SR nonlinearity theory is researched and a new Schumann Resonance anomaly monitoring method on the ionosphere nonlinearity is proposed.Yampolski gave the HF-SR (high frequency-Schumann Resonance) theory taking account the atmosphere electric field. On the basis of this, HF-SR multi-interaction theory is discussed. The distribution of Schumann Resonance electric field in the earth-ionosphere cavity is researched. Combining the research of ionospheric cross modulation, the nonlinearity interaction of HF-SR in the lower ionosphere is researched. The interaction of round-the-world signal and Schuamnn Resonance is calculated combining the experiment carried out by Ukraine national academy of science. The result shows that similar modulation depth can be obtained by receiving round-the-world signal and the direct reflection signal from ionosphere. Thus, the short wave time service signal called BPM is chosen to construct a observatory in the eastern coastal area of China.(4) The simple design of Schumann Resonance observation on ionosphere nonlinearity is put forward and the system is developed.The simple design plan of Schumann Resonance observation on ionosphere nonlinearity is put forward on the basis of theoretical analysis. High frequency electromagnetic wave propagation engineering calculation and high frequency atmospheric radio noise, man-made noise and receiver noise inside is researched. The design requirement of receiving antenna of the system is made. According to the design requirements, shortwave crossed dipole antenna and the zero-frequency shortwave receiver are designed. The observation system development is completed.(5) Data of lower ionosphere Schumann Resonance for a long-term are analyzed, and the corresponding methods and results are studied.A long period of monitoring experiment was operated after the observation system completion. Schumann Resonance was successfully obtained from high frequency signal. The differential filtering method, subsection normalization method and curve-fitting method are put forward to abstract Schumann Rresonance. The observation results are compared with international ones. Two earthquake cases, which happened near BPM propagation paths in observation period, are analyzed. Possible Schumann Resonance anomaly related to the Ms 4.7 earthquake in Zhoukou, Henan province is obtained, according to the Schumann Resonance anomaly phenomena observed by Japanese scholars, Hayakawa and Ohta.