安徽区域数字化水位和水温远场大震同震响应分析

SIMULTANEOUS SEISMIC RESPONSE ANALYSIS ON LARGE EARTHQUAKES IN FAR FIELD OF DIGITAL WATER LEVEL AND WATER TEMPERATURE IN ANHUI PROVINCE

利用安徽台网记录的2010年以来全球29次Ms≧7.7级地震,从"一震多井"和"一井多震"2个方面,结合井孔地质水文条件,分析安徽台网水位水温观测对全球不同大震的远场效应。研究得出:①同震响应产生的水位阶变,主要由于压应力或拉应力作用于含水岩体时,造成含水层的孔隙压力发生变化所致;②井孔各含水层水压受地震应力变化波动水位出现震荡,由于井孔内混合水含量比震荡打破其内在平衡,故水温随水位震荡出现阶变,水温变化滞后于水位震荡变化;③远场效应的各项特性主要与该井地下结构所受应力变化强弱有关,地震能量释放波及其地下结构变化,导致井中水位、水温观测产生远场效应。这些研究结果,为安徽流体观测异常变化分析提供了一定的物理基础,也为安徽及邻近地区的地震预测预报研究提供了一定的理论依据。

Taking 29 global earthquakes ( M ≥7.7) since 2010 as examples, from the view of “one earthquake corresponding to many wells” and “one well corresponding to many earthquakes”, the authors analyzed the far field effect of groundwater observational network in Anhui province with water level data and temperature data. The results are shown as following:①Due to the variation of pore pressure caused by the compressive stress or tensile stress acting on the water bearing rock mass, the water level change is caused by the co-seismic response;②The borehole pressure of aquifer by the earthquake stress fluctuation level shocks, because of the well bore mixed water content than the shock to break its inner balance, so the water temperature with the water level shocks order variable, temperature change lags behind the shock level changes;③The characteristics of the far field effect are mainly related to the stress variation of the underground structure, the seismic energy release wave and the change of the underground structure, which results in the far field effect of the well water level and water temperature observation. These results provide a physical basis for the analysis of the abnormal variation of fluid observation in Anhui, and provide a theoretical basis for the prediction of earthquakes in Anhui and adjacent areas.