Grey prediction of seismic activity in the Three Gorges area of the Yangtze River

On the basis of historical earthquake data and recent observations, two gre y models prediction of the next seismic active period and the maximal magni tude of earthquakes which might occur during that period are constructed on the basis of the grey theory. As predicted by the two models, the next sei smic active period would last 79 years, and that the maximal magnitude of e arthquakes occurring within the period would not exceed 5.2. These results provide an important basis for the assessment of earthquake risks and reduc tion of disasters in the Three Gorges area.