Primary Analysis of Synthetical Characteristics of Abnormal Image of Medium-strong Earthquakes in North Shanxi

Taking tectonic block of the investigated region as background,the abnormal imagine of crustal deformation,underground fluid,electromagnetism and earthquake observation before the 1989 Datong earthquake of M6.1,the 1991 Datong earthquake of M 5.8 and the 1991 Xinzhou earthquake of M5.1 are analyzed.The relation and combination of each item of anomalies in time and space are figured out and the inner link of them to the seismic process are confirmed.The results show that the abnormal time before medium-strong earthquakes of M5.0 in north Shanxi is nearly three years,with quite obvious locked area or empty segment formed in epicenter area.The starting time and space distribution of precursor anomaly are quite accordant the anomaly of small earthquake activity.