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一般的了解，但我们仍然不能完全理解地震破裂是如何形成和传播的，以及它们为什么会停止。此外，地震的频率和大小的控制因素是正在进行的研究课题。在我们的建议中，我们的目标是通过对南非深部金矿的地震活动性进行全面研究来解决这些问题。在这里，我们发现了一个独特的情况，即地震活动由采矿引起的地震和触发的余震组成。我们假设，由采矿活动或主震引起的应力扰动体积的有限性和几何形状控制着破裂的成核和传播，并影响频率-震级分布。为了验证我们的假设，我们将采用新的方法来研究深部矿井的地震活动性，包括基于波形的方法和概率方法。这些方法最近得到了完善，并成功应用于流体注入诱发地震，包括破裂传播成像、破裂指向性分析和震级统计的标度研究。在这项建议中，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，这种地震活动也以有限的体积发生，这将有助于更好地了解孕震过程，特别是有助于改进评估和减轻采矿环境中的地震危害。

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.