THE ANALYSIS OF M_L4 EARTHQUAKE QUIESCENCE IN NORTH CHINA

This paper analyzed the corresponding relationship between quiescence of M_L4 earthquake and medium shocks since 1980in North China Area (33°~43°N,108°~125°E),and discussed the differentiate of seismic seismic episode in the area according to M_S≥6 earthquake activity.The main conclusions are as follows: (1)The North China area is in a seismic quiescence period after the fifth seismic episode and M_S≥ 6 earthquake has not occurred for more than 16 years,and it will enter to a new seismic episode for some time to come. (2)The Corresponding relationship between quiescence and earthquake is very different at different time of the earthquake scene.From 1980 to 2000,there is a better corresponding relationship between M_L4 earthquake and M5 earthquake;After 2000,the relationship is appropriate between M_L4 earthquake and M_L5.2 earthquake. (3)Shandong Laizhou M_L5.0 earthquake broke the quiescence of M_L4 earthquakes in 189days,although there is a M_L5.1 earthquake occurred at yellow sea,it may be in risk of earthquakes of M_L5.2 or above in the future in North China area