Improving the estimation of detection probability and magnitude of completeness in strongly heterogeneous media, an application to acoustic emission (AE)
Improving the estimation of detection probability and magnitude of completeness in strongly heterogeneous media, an application to acoustic emission (AE)
复制标题
改进强异质介质中检测概率和完整性大小的估计，在声发射 (AE) 中的应用
DOI：
10.1093/gji/ggt049
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发表时间：
2013
影响因子：
2.8
通讯作者：
Becker
中科院分区：
文献类型：
--
作者：
Maghsoudi;Hainzl;Kaiser;Becker
完整性震级（Mc）的可靠估计对于正确解释地震目录是必不可少的。在采矿环境中，由于坑道、洞穴、断裂区、多孔介质和不同的矿物体的存在，以及地震活动性空间分布不均匀的结果，Mc的空间分布可能变化很大，难以评估。我们应用3-D修改的概率幅度的完整性（PMC）的方法，它依赖于网络检测能力的分析。在我们的方法中，检测事件的概率取决于它的大小，源-接收器的欧几里德距离和源-接收器的方向。建议的方法提出了在采矿环境中的完整性的大小的空间分布的研究，并在这里被应用到2个月的声发射（AE）数据集记录在Morsleben盐矿，德国。密集的地震网络和包括100多万个事件的大型数据集使该方法能够进行详细的测试。这种方法是专门针对强非均匀介质提出的。此外，它还可以用于特定的网络安装，传感器的灵敏度取决于入射波的方向（例如，一些压电传感器）。在不存在强异质性的情况下，应使用标准PMC方法。我们发现，PMC估计在矿井中强烈依赖于源接收器的方向，并不能正确地占使用标准的PMC方法。然而，当采用所提出的PMC方法的3-D修改时，结果可以得到改善。我们的一个中心的水平和垂直部分的分析产生的完整性的幅度约Mc 1（AE幅度）在网络的中心，这增加到Mc 4在网络以外的进一步距离，最好的检测性能估计为NNE-SSE延长区域，这对应于低衰减盐体的走向。我们的方法为我们提供了有关传感器检测地震能力的小尺度细节，这可以与特定方向上的异质性的存在相联系。降低检测性能的存在下，强结构的不均匀性（空腔）证实了合成波形建模在非均匀介质。
Reliable estimations of magnitude of completeness (Mc) are essential for a correct interpretation of seismic catalogues. The spatial distribution ofMcmay be strongly variable and difficult to assess in mining environments, owing to the presence of galleries, cavities, fractured regions, porous media and different mineralogical bodies, as well as in consequence of inhomogeneous spatial distribution of the seismicity. We apply a 3-D modification of the probabilistic magnitude of completeness (PMC) method, which relies on the analysis of network detection capabilities. In our approach, the probability to detect an event depends on its magnitude, source–receiver Euclidian distance and source–receiver direction. The suggested method is proposed for study of the spatial distribution of the magnitude of completeness in a mining environment and here is applied to a 2-months acoustic emission (AE) data set recorded at the Morsleben salt mine, Germany. The dense seismic network and the large data set, which includes more than one million events, enable a detailed testing of the method. This method is proposed specifically for strongly heterogeneous media. Besides, it can also be used for specific network installations, with sensors with a sensitivity, dependent on the direction of the incoming wave (e.g. some piezoelectric sensors). In absence of strong heterogeneities, the standards PMC approach should be used. We show that the PMC estimations in mines strongly depend on the source–receiver direction, and cannot be correctly accounted using a standard PMC approach. However, results can be improved, when adopting the proposed 3-D modification of the PMC method. Our analysis of one central horizontal and vertical section yields a magnitude of completeness of aboutMc≈ 1 (AE magnitude) at the centre of the network, which increases up toMc≈ 4 at further distances outside the network; the best detection performance is estimated for a NNE–SSE elongated region, which corresponds to the strike direction of the low-attenuating salt body. Our approach provides us with small-scale details about the capability of sensors to detect an earthquake, which can be linked to the presence of heterogeneities in specific directions. Reduced detection performance in presence of strong structural heterogeneities (cavities) is confirmed by synthetic waveform modelling in heterogeneous media.
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