设定场源参数的区域重力微变化特征与模型实验

流动重力测量作为地震前兆监测手段之一, 所得到的区域重力场微变化信号反映地壳内部密度变化、 地壳变形、 流体运移等信息。 采用定量化和模型化方法研究与地震孕育相关的重力场变化信号时空特征, 对于构建地震预报定量化指标体系具有重要意义。 通过设定场源参数构建了数值模型, 正演得到了多组不同场源条件下的重力场变化模型; 通过模型对比, 分析了重力变化与重力梯度变化对不同类型场源参数的关系。 研究结果表明: 重力垂直梯度变化对异常体边界比较敏感, 特对浅部异常更为敏感, 适用于圈定异常体范围。 以此为基础提出了观测系统的优化测量方案, 以及对观测精度的需求。 研究结果对于构建地震预报指标参数, 优化流动重力观测系统具有一定参考意义。

Model Testing and Forward Modeling of Regional Micro-gravity Changes based on Known Field-source Parameters

Mobile regional gravity measurement is one of the most important means in earthquake monitoring, and the observed micro-gravity changes can reflect the density anomalies of the deep crust, forming process of crustal structure and earthquake. Gravity changes before earthquakes have been widely reported. How to optimize the observation system, and identify gravity change signals, which is in the potential inner crust and within the depth range of earthquake preparation are very important problems. By using numerical model test, we present different gravity changes and features of these anomalies from different field-source parameters, and analyze gravity changes and gravity gradient changes with different parameter models. We also conclude that gravity gradient is more sensitive to the boundary of abnormal body, and compared with gravity, it is more efficient to identify the shallow anomalies and more easier to outline the boundary of abnormal body. With the putting forward of optimization scheme of the observation system and the increasing of observation accuracy, we can further combine it to the “equivalent source” to infer the sources of the field, and analyze the dynamical feature of seismogenic zone.