Observation of ULF (Ultra-Low-Frequency) electromagnetic emissions associated with earthquakes

Short-term prediction of earthquakes is still an urgent and important subject for seismo-active countries like Japan. There have been recently found a lot of convincing evidences on the presence of electromagnetic phenomena associated with earthquakes. One of the most promising candidates for short-term earthquake prediction is ultra-low-frequency (frequency less than 10Hz) (abbreviated as ULF) electromagnetic emission. We first review earlier observational facts, and then show our latest results, especially on the existence of such ULF emissions by means of sophisticated signal processing. Finally, we discuss the generation and propagation mechanisms of those seismo-ULF emissions.