Proposing and using the concept of precursor field stability, the precursory observational data before moderate earthquakes on the boundaries of Henan, Sandong and Hebei are analyzed.

• 提出了前兆场稳定度的概念，利用前兆场稳定度的方法对中强地震前豫鲁冀交界区不同台站和不同手段的前兆观测数据进行分析。