海原4.9级地震前兆异常和预报

PRECURSORY ANOMALIES AND PREDICTION OF THE M_S 4.9 EARTHQUAKE IN HAIYUAN, NINGXIA REGION

１９９８年７月在宁夏回族自治区海原县发生４．９级地震，震前根据所掌握的资料和对异常的分析认识，宁夏地震局作出了趋势、中期及一定程度的临震预报，宁夏固原地震台和宁夏固原行署地震局作出了临震预报。对这次地震的地震序列特点、发震构造和震后趋势判断依据及前兆异常的演化过程，特别是对临震异常进行了分析研究，并对预报中存在的问题进行了讨论。

An M S 4.9 earthquake occurred in Haiyuan County in Ningxia Hui Autonomous Region on July 29, 1998. Before the earthquake, the seismological Bureau of Ningxia Hui Autonomous Region judged the tendency, medium term and impending earthquake prediction to a certain extent. Guyuan Seismic Station of Ningxia Seismological Bureau and Guyuan Administrative Office of Ningxia Region have made explicit impending earthquake prediction. In this paper, the features of earthquake sequence, seismogenic structure and the evidence on which we have made our postseismic tendency judgement have been introduced. The evolutional course of precursory anomalies has been analyzed. Especially the discussion has been made on the analytical consideration regarding the impending earthquake anomalies, finally on the prediction succession and problems existed.