Abstract: In this paper, the detection criterion and quantification of deformation anomaly inten-sity on the basis of the F-detection theory have been discussed. We have applied these def-initio ns to study the heterogeneity of anomalous deformation intensity before the Datong and Lijiang earthquakes by using the observed deformation data, and have also compared the research results with earthquake activity characteristics. It is demonstrated that the quasi-synchronous deformation anomalies about 1. 5 year before the earthquake in a region can be detected, and then the anomaly intensity should be increased in the former anomalygap before earthquake occurrence. Therefore the authors consider that the key of earth-quake prediction is to identify the stages of earthquake preparation because the precursors may occur in different forms during various preparation stages.

Key words: Earthquake activity Anomaly intensity, Heterogeneous distribution of anomaly intensity