Detection and radiation area estimation of anomalous environmental electromagnetic wave related to earthquake precursor

Anomalous radiation of environmental electromagnetic (EM) wave is reported as a portent of earthquake. We are observing environmental electromagnetic waves in ELF band all over Japan. Our goal is to predict earthquakes by detecting anomalous EM radiation. We have proposed various detection methods of anomalous radiation. However, the earthquake prediction requires the estimate of EM radiation area in addition to the detection of anomalous radiation. If the EM radiation area can be estimated, we can obtain information about the occurrence area of possible future earthquake. In this paper, we propose the method of detection and area estimation in the anomalous EM radiation by using cross-correlation in magnetic field azimuth. We apply the proposed method to the observed signals before the large earthquake that occurred in the past, and we detect an anomalous radiation and estimated the EM radiation area.