EVOLUTION AND SYNCHRONISM OF THE MEDIUM AND SHORT TERM ANOMALIES BEFORE ZHANGBEI M6.2 EARTHQUAKE

the characteristics and synchronism of the crustal deformation and subsurface fluid anomalies observed by Huailai Seismostation before Zhangbei M6.2 earthquake in 1998 are studied. Evolution of the anomalies from short term to imminent period shows phasic feature: crustal deformation anomalies appear earlier than fluid anomalies; imminent anomalies appear concentratively. That CO₂, water Hg and cubic strain anomalies appear two month before the earthquake shows the synchronism of the anomalies.