Infrasound waves caused by earthquake on 12 July 1993 in Japan

Remarkable infrasound wave trains have been recorded at Beijing Infrasound Observatory at 21:21 BT (Beijing Time) on July 12,1993.It is a complete set of local waves (including primary wave,shear wave and Rayleigh waves) and epicenter infrasound waves caused by an earthquake in Japan.There are periods of 12 s,12 s,30 s,and amplitudes of 0.8 Pa,0.4 Pa,1.3 Pa,and durations of 3.4 min,1 min,12 min respectively.The epicenter infrasound waves have period of 137 s,and its maximum amplitude of 6.9 Pa and durations 28 min.They were superimposed on a much longer and more usual series of waves with period about 12 min and amplitude 10 Pa;such waves,which are of natural origin,are characteristically received during meteorological inversions.