Seismicity pattern characteristic and empirical indexes for strong earthquakes prediction

According to the studies to judge the risk of a strong earthquake with 10 years scale and the prediction experience of strong earthquakes from 1972 to 2002 in Sichuan province,we summarize the seismicity characteristics before the shallow-focus earthquakes with magnitude equal to or greater than 4.7 occurred in main land of China from 1920 to 2002 and then we put forward 12 empirical prediction indexes from 47 strong earthquakes occurring in main land of China.These indexes include a main seismicity zone,multi-earthquakes period,related seismic series,anomalistic seismicity patterns,increasing seismicity patterns of regions(which include signal earthquakes,induced earthquakes,earthquake zoning),related earthquakes,window earthquakes,recurring intervals,no-earthquakes in some region,no-earthquakes in some belts,and periods between strong and weak seismicities.These comprehensive indexes are tested in the events of 47 earthquakes.These indexes are of valuable in the practice of earthquake prediction.