The dynamic characteristics of deformation anomaly at fixed observational sites prior to the Zhangbei M(s)6.2 earthquake

Based on the results of tilting observation in the fault depression of Yanshan mountain, this paper discussed the dynamic features of anomalies in the depression and boundary area. It was demonstrated as follows: (1) The relative quiet of tilting along the EW direction and the speeding of tilting toward S along NS direction have been shown one year before Zhangbei M(s)6.2 earthquake, and the sudden rebound of tilting along the NS direction before a half-year has also been detected in the region close to the epicenter; (2) The divergence of tilting along the EW and NS directions shows the synchronous movement feature with decreasing tendency two years before the earthquake; (3) At least two times of obvious anomalous marks expressed by the anomaly intensity AF have been shown at sites in the depression.