A PRIMARY STUDY ON THE CORRELATION OF THE EARTHQUAES AND INDUCED FORE-SHOCK IN NINGXIA AND ITS NEIGHBORINGS

The correlation of the earthquakes and induced foreshock in Ningxia a nd its neighboringsregions are described in this paper.The results show that the earthquakes occurred in Ningxia and its neighboring regions are correlated with the eathquakes of given specific regions,such as the boundaries of Ordos block,Jiangsu province,the Qinghai-Xizang plateau block,and Helingeer regionof lnner Mongolia.In addition,the eahth-quakes between the two seismic regions of Yinchuan plain and Xi-Hai-Gu within Ningxia province are of correlation too.The time interval of two correlative earthquakes is about a few days to ten-oddmonths.Induced fore shock of several moderate strong earthquakes of Ningxia and its neigh-boring regions since 1970 are quite clear.But how to distinguish foresho-ckes before big earthquakes is a considerable difficult problem at present.