The Observation and Direction Findings of ULF Electromagnetic Emissions Possibly Associated with Earthquakes

Chubu University has established ULF/ELF electromagnetic observation network in order to study seismo-electromagnetics. We have observed ULF electromagnetic emissions radiated from the direction of the epicentral region of the 2004 Mid Niigata Prefecture (Ohta et al., 2005) and the 2004 Sumatra earthquakes (Ohta et al., 2007). In this study, we estimated the direction angle of the ULF emissions observed at three observation stations (Nakatsugawa, Shinojima and Minami Izu) before earthquakes. We found that ULF emissions observed at Nakatsugawa station have been propagated possibly from the direction of the epicenter of the 2007 Noto Hantou earthquake. And also we found that ULF emissions observed at three observation stations have been propagated possibly from the epicentral area of the 2008 Iwate-Miyagi Nairiku earthquake. However, the number of ULF emissions whose direction angle was pointed to the epicenter was not outstandingly large. If we don’t know the location of the earthquake, this would make us to misguide the location of the epicenter. The observed ULF emissions possibly propagated from the epicentral region were not so convincing enough. And so we need more event studies.