In this paper, using the observational data of seismological stations of Sichuan province, the Variations of some seismometry indications before the occurrences of moderate earthquake have been discussed.
Principal aspects are shown:(1)Variations of assumed stress strop; (2)Variations of β=M_L/lgτ; and(3)Variations of θ=K_s-K_p.A simple method for measuring the seismic moment is also proposed here and the seismic moments of some earthquakes have been measured. Finally, we hare discussed the possibility of the predication of an earthquake by using the ratio for the envelope of seismic waves.