Abstract: Through study and application of “Guide to Earthquake Prediction by the Seismo logical Method”, based on the practice of long-and medium-term earthquake prediction in recent years, the authors discovered that the inhomogeneous degree of seismicity (GL value) is a useful parameter for describing the temporal and spatial inhomogeneous distribution of small and moderate earthquakes prior to the strong ones. It can reflect the characteristics of earthquake precursors in short-medium term, that is, the activity of small earthquakes changes from both stable and unstable statuses before a moderate or strong earthquake. Synthesizing the study of the moderate and strong earthquake predictions in Gansu and its neighbouring area, and applying GL value in time and space scanning of earthquakes occurred in the study region, it is found that one or two years before occurrence of all moderate and strong earthquakes (M_S≥5.4) except a few events, the activity of small earthquakes (M_S≥2.0) shows obviously the inhomog eneous feature of seismicity (GL≥1.0), 300 km from the epicenters during different periods.

Key words: Analysis of medium-and short-term precursors, Seismic inhomogeneous degree, Time-space scanning of GL value, Monitoring and synthesizing the study of the prediction