On the basis of quadrant features of the precursors in geo-electricity and deformation in the case of Tangshan earthquake and Datong earthquake in North China, the same feature of geo-electricity and deformation precursors before the Zhangbei earthquake has also been found. It seems that the existence of the quadrant behavior is not accidental, which might be related to existence of the earthquake generations. It is known in terms of rock experiment and theoretical analysis that there exists actually quadrant feature in earthquake-generating process with the range of quadrant spatial distribution unfixed, showing features of (gradual increasing ? maximum ? lessening slightly(, showing that the increasing zone and the decreasing one (or compressing zone and expanding one) of the quadrant in the near-source region could be different from that in the far-source region. Based on the knowledge of quadrant characters of earthquake precursors, we analyze space distributions of different types of precursor anomalies which may be a useful reference for one to predict the location of a strong earthquake occurrence.
