跨断层扰动协调比异常提取方法与效能评估及其在云南地区的应用

Extraction of the Coordination Ratio Anomaly of the Cross-fault Disturbance and Its Efficiency Evaluation and Application in Yunnan

跨断层异常的识别和提取是震情跟踪分析的难点,协调比的计算在兼顾震前断层活动状态内在机理的同时,在异常识别方面也有显著优势,但传统的协调比计算存在因计算起点不同导致结果不一致的问题。通过提出扰动协调比计算方法,用于表征强震发生前可能出现的区域应力场扰动导致断层运动状态偏离背景的现象,分析断层运动状态变化与地震之间的内部联系。以云南地区11处跨断层资料为例,针对川滇地区M≥6.5强震样本开展了震例总结和综合预测指标的提取,通过等信度和非等信度异常识别方式,合成多个预测指标。结果表明:扰动协调比计算方法在跨断层场地异常活动状态的提取中有一定优势,与周边强震存在较好的相关性,对于强震可能发生时间可提供中期尺度的判定依据,预测指标均通过了效能检验。

The identification and extraction of the anomalies from cross-fault monitoring have always been a problem for earthquake prediction.The coordination ratio method considers the inherent mechanism of the fault activity before the earthquake occurs,and has advantages in identification of earthquake anomalies.However,the coordination ratio method will give inconsistent results due to different zequines.In this paper,a new calculation method of coordination ratio for disturbance is proposed to characterize the possible disturbance of the regional stress field that may cause the fault’s movement deviating from the background value before a strong earthquake,thus,to analyze the relation between the fault’s movement with earthquakes.We take the cross-fault data at 11 observational sites in Yunnan,to retrospectively extract the comprehensive indicators for earthquake prediction for the historical M≥6.5 strong earthquakes in Sichuan and Yunnan.In this way,we get multiple indicators for earthquake prediction,and all of them have passed the efficacy test.The new method can help to identify the fault’s abnormal movement and to extract indicators for the prediction of strong earthquakes.