A study on anomalous signal detection using HMM for ELF electromagnetic wave

A seismic radiation emitted from the earth´s crust is useful for predicting earthquakes. The electromagnetic (EM) wave in the Extremely Low Frequency (ELF) band have been observed at many places in Japan. In this paper, we propose the anomalous signal detection method based on HMM whose input vector is the amplitude density distribution of an EM wave. The amplitude density distribution is calculated from the image of an EM wave data. The optimal scale of an image to calculate an amplitude density distribution and the optimal number of states of HMM are investigated to achieve an accurate detection.