Study on analysis of EM radiation source based on eigenvector

Occurrence of anomalous Electro-Magnetic (EM) radiation is known as a precursor of earthquakes. Our goal is to locate anomalous EM source caused by seismic activity for earthquake prediction. For the purpose, we have been measuring EM wave of 223 Hz at about 40 sites in Japan. Measured signal contains much noise caused by far thunder lightning around equators, human activities, near field lightning and so on. This paper shows that the principal component analysis methods for covariance matrices of measured signals are effective for removing a component caused by thunder lightning around equator and for separating each EM source. Moreover, it is shown that a result of elimination of noise caused by far lightning around equators, estimation of thunder lightning location in near field agrees with real thundercloud observed by radar system, and estimation of sources of anomalous EM radiation occurred before earthquake.