Rupture processes and magnitude statistics of inducedearthquakes and aftershocks: A detailed view from deepSouth African gold mines

尽管我们对地震过程有了一般的了解，但地震破裂是如何成核和传播的，以及它们为什么会停止，仍然没有完全弄清楚。此外，地震的频率和规模的控制因素也是正在进行的研究主题。在我们的提案中，我们的目标是通过全面研究南非深部金矿的地震活动来解决这些问题。在这里，我们发现了地震活动既包括矿震又包括触发余震的独特情况。我们假设，无论是采矿活动还是主震，应力扰动体积的有限性和几何形状控制着破裂的成核和扩展，并影响频率-震级分布。为了验证我们的假设，我们将应用新的方法来研究来自深井的地震活动，其中包括基于波形的方法和基于概率的方法。这些方法最近被详细阐述并成功地应用于流体注入诱发的地震，包括破裂传播成像、破裂方向性分析和震级统计尺度研究。在这项提案中，我们希望测试这些方法对南非深部矿山地震活动的适用性，这种活动也是以有限的体积发生的，这将有助于更好地了解地震孕育过程，特别是有助于改进采矿环境中的地震灾害评估和减轻。

Despite our general understanding of earthquake processes, it is still not fully understood how earthquakes ruptures nucleate and propagate and why they stop. Furthermore, the controlling factors of the frequency and the size of earthquake are subject of ongoing research. In our proposal, we aim to address these questions with a comprehensive study of seismicity in deep South African gold mines. Here, we find the unique situation that the seismicity consists of both mining-induced earthquakes and triggered aftershocks. We hypothesize that the finiteness and geometry of the volume of stress perturbation, either by mining activity or by a main shock, controls the nucleation and propagation of ruptures and influences the frequency-magnitude distribution. To test our hypothesis, we will apply novel approaches to the seismicity from the deep mines which involve both waveform-based and probabilistic methods. These methods were recently elaborated and successfully applied to fluid injection induced earthquakes and include rupture propagation imaging, rupture directivity analysis, and studies of the scaling of the magnitude statistics. In this proposal, we want to test the applicability of these approaches to the seismicity in deep South African mines, which also occurs in a finite volume, which will contribute to a better understanding of seismogenic processes and, in particular, to an improved assessment and the mitigation of seismic hazard in mining environment.