STUDY ON THE DYNAMIC FEATURES OF SUBSURFACE FLUID PRECURSOR BEFORE HUICHUN M7.0 DEEP EARTHQUAKE

The characteristics of medium term, short term and imminent anomalies in subsurface fluid before Hunchun M7.0 deep earthquake are analyzed.The distribution of anomalies has phasic variation and centrality.The occurrence time of anomaly is related to the epicentral distance.In medium term, the anomalies concentrate from outside to the epicenter, and its rate is very slow;when in short term stage, the rate becomes large.In imminent stage, the anomalies diffuse from the epicenter to the outside, and its rate rapidly increases.