Interpretation in terms of gyrotropic waves of Schumann-resonance-like line emissions observed at Nakatsugawa in possible association with nearby Japanese earthquakes

►Anomalous Schumann resonance phenomena and line emissions are observed in Japan. ►These are possibly associated with recent nearby earthquakes. ►The intensity of SR modes increased before these large EQs. ►Line emissions are detected at the frequency shifted from the SR modes. ►These anomalous phenomena are interpreted in terms of gyrotropic waves.