On the Role of Load and Pore Pressure Diffusion in the Triggering of Seismicity at Monticello Reservoir

本研究旨在研究南卡罗来纳州蒙蒂塞洛水库蓄水后，荷载与弹性孔压增加和孔压扩散在触发地震活动中的相对作用。蒙蒂塞洛的独特之处在于，在充填之前、期间和之后进行了广泛的地质、地球物理和地震学研究，使其成为世界上研究最好的水库诱发地震事件之一。要确定荷载和孔压扩散的相对作用，需要分析准确的定位地震的空间和时间模式，以及充填过程中发生的诱发应力和孔压变化。由于现场的地质条件极为不均匀，为了获得准确的震源位置，开发三维速度模型是必要的。我们建议在详细的地质和地球物理数据的约束下，通过高质量的地方地震震相数据的反演来建立这样的模型。使用改进的速度模型重新定位初始地震活动将提供活动的准确空间和时间历史。通过与载荷应力的比较，可以区分载荷和孔压扩散在触发Monticello水库地震活动中的相对作用。这些研究的结果将直接适用于世界各地与水库相关的RIS的控制。

The proposed studies are aimed at studying the relative roles of loading with accompanying elastic pore pressure increase and pore pressure diffusion in triggering seismicity at Monticello Reservoir, S.C. following its impoundment. Monticello is unique in that extensive geological, geophysical, and seismological studies were conducted prior to, during, and after filling, making this one of the best studied cases of reservoir induced seismicity in the world. Determination of the relative roles of loading and pore pressure diffusion requires analyses of accurate spatial and temporal patterns of well located earthquakes together with the induced stresses and pore pressure changes which occurred during filling. As the geology at the site is extremely heterogeneous, development of a three dimensional velocity model is necessary to obtain accurate hypocentral locations. We propose to develop such a model by inversion of high quality local earthquake phase data within constraints imposed by detailed geological and geophysical data. Relocation of initial seismicity using the improved velocity model will provide an accurate spatial and temporal history of the activity. From a comparison of these patterns with that of the load induced stresses it will be possible to differentiate the relative roles of loading and pore pressure diffusion in triggering the seismicity at Monticello Reservoir. The results of these studies will be directly applicable to the control of RIS associated with reservoirs worldwide.