Survey of anomalous Schumann resonance phenomena observed in Japan, in possible association with earthquakes in Taiwan

Abstract

The observation of ELF Schumann resonances in Nakatsugawa, Japan has suggested the presence of anomalous behavior in Schumann resonances (that is, the main point is the enhancement at the fourth (or the third) harmonic) at Nakatsugawa, and we have indicated that those anomalies in the Schumann resonances at Nakatsugawa are highly likely to be associated with the large earthquakes in Taiwan. This paper is intended to provide the statistical significance of those Schumann resonance anomalies in possible association with earthquakes in Taiwan on the basis of the ELF observation during the period from the beginning of 1999 to the end of 2004 (6 years). With the criterion of the magnitude greater than 5.0, there were observed 33 earthquakes in and around Taiwan, and the Schumann resonance anomaly is observed for 9 earthquakes (so that the anomaly percentage will be 9/29 (because no observation for 4 earthquakes)). Twenty nine earthquakes included 7 earthquakes in the land, while other 22 earthquakes took place in the sea. It is surprising that anomalous Schumann resonances are observed prior to all the land earthquakes. Two sea earthquakes from the 22, had the anomalous Schumann resonances, but these two earthquakes had the following characteristics (one was the largest magnitude, and another, the shallowest). The paper discloses the causative link between the anomalous Schumann resonances and earthquakes in Taiwan. Especially, the land earthquakes with large magnitude are found to trigger the anomalous Schumann resonances.