DISCUSSION ON MID-SMALL EARTHQUAKES ACTIVITY CHARACTERISTICS BEFORE MID-STRONG EARTHQUAKE IN THE WEST PART OF NORTHERN TIANSHAN MOUNTAIN

Through analyzing earthquakes activity tendency,time-space characteristics of moderately small earthquakes before strong earthquakes,and doing qualitative and quantitative summary of strong earthquakes activity characteristics in the study area,the earthquake prediction level and reliability would be improved.The earthquakes activity characteristics before moderately strong earthquake in the study area are analyzed in the following :(1) In the study area,the activity rate of Kashi river fault was the highest and the lowest existed in the west part of Yilianhabierga fault.The MS 5.0 earthquakes were active in the southern fault of Dzungarian Basin;(2)There was obvious 3 to 4 earthquakes activity characteristics along Kashi river fault and southern fault of Dzungarian Basin.They formed seismic belt,seismic gap or gathered around the main earthquake;(3)The moderately strong earthquakes occurred in group and the interval was not more than 2 years;(4)The possibility of moderately strong earthquake was bigger in 6 months after 4 sign earthquake.