TRACING FOR EARTHQUAKE SITUATION AND SYNTHETIC PROBABILITY PREDICTION FOR EARTHQUAKE OCCURRENCE TIME

The microearthquakes' activities before the fracture of the main quake,the dynamic anomaly images of crustal deformation anomalies and its concomitant precursors of underground water,hydrochemistry and earthresistivity are analyzed.The precursory anomaly data before some medium and strong earthquakes in Hebei province and its vicinity from 1970 to 1988 are studied.Based on the above study we extracted the variation character of 9 precursory anomaly factors,established the probability prediction model with each factor,and calculated the probability of earthquake during the different stage after a precursor took place.At the end,under the circumstance of the precursors taking place one by one with time,using equation (9) we calculated the synthetic probability of each kind (A,B,C)anomaly and its variation with time.The time stage that synthetic probability value was relatively high is choosed as occurrence time of potential earthquakes.The method was test in the paper.The results show that the synthetic probability high values of precursors were basically consistent with earthquake occurrence time.The results in this paper are significant to tracing prediction in long term,medium term and short term.