重力观测是三峡水库地区地震监测的重要组成部分。本文系统分析了三峡重力网的空间覆盖范围、空间分辨力以及重力变化观测精度,结合现有重力变化异常空间范围和量级与地震震级之间经验指标,对三峡重力网的地震监测能力进行了评估。结果表明,三峡重力网在空间分辨力和观测精度方面均达到了4级以上地震的监测要求,空间覆盖范围介于5级地震重力变化异常场范围经验指标的上、下限之间,因此重力网对于4～5级地震具有较好的监测能力,但对于监测5级以上地震存在无法获取重力变化异常完整形态的可能。此外,三峡水库水位变化引起的重力效应对重力观测具有明显的影响,在计算水位变化重力效应时,应采用与重力观测数据相同时刻的水位数据。

Gravity observations constitute a pivotal element within the seismic monitoring framework of the Three Gorges Reservoir region. This paper undertakes a comprehensive analysis of the spatial coverage,resolution,and measurement precision of the Three Gorges gravity network. Utilizing empirical benchmarks for spatial extent and the magnitude of gravitational anomalies in relation to seismic magnitudes,the seismic monitoring capacity of the network is rigorously assessed. The results show that the spatial resolution and observational precision of Three Gorges gravity network are adequate for the detection of earthquakes magnitude 4 and higher. Nonetheless,the spatial coverage extends only partially within the empirically defined parameters for the gravitational anomaly field range associated with magnitude 5 earthquakes. Consequently,while the network demonstrates robust monitoring capabilities for earthquakes ranging from magnitude 4 to 5,its ability to fully delineate the gravitational anomaly patterns triggered by larger seismic events remains uncertain. Furthermore,we find that gravitational variations induced by fluctuations in the water level of the Three Gorges Reservoir exert a considerable influence on gravity measurements. It is imperative to account for these effects by integrating contemporaneous water level data into the gravity observation calculations.

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长江三峡工程地震监测总站及地壳形变监测网络升级项目(0404552)、2022-2024年长江三峡库区地震监测系统运行维护及地震应急工作项目(1299235)、中国地震局地震研究所所长基金资助项目(202326342)共同资助