Enhancing seismic moment tensor inversion via meta-heuristic optimization: A case study on mining-induced seismicity at fankou Lead-Zinc mine

Abstract

Moment Tensor Inversion (MTI) plays a pivotal role in seismology, employed for discerning focal mechanisms and analyzing microseismic (MS) events. However, the efficacy of MTI is intricately tied to the accuracy of its input parameters. This paper introduces a systematic exploration of the application of meta-heuristic algorithms to enhance seismic MTI through meticulous parameter optimization. The primary objective of this study is to harness advanced optimization techniques, mitigating challenges associated with nonlinearity, trade-offs, and computational efficiency, thereby enhancing the precision and reliability of source parameter estimates. Against the backdrop of 17 MS data and 125 blasting data points from the Fankou Lead-Zinc Mine, three meta-heuristic algorithms—Moth-flame optimization algorithm (MFO), Multi-Verse Optimizer (MVO), and Dragonfly algorithm (DA)—were strategically employed to optimize MTI. The optimization process specifically targeted the adjustment of three critical input parameters: anomaly sensor, P-wave first arrival picking threshold, and velocity model, with the overarching goal of refining the quality of the focal mechanism solution. Customized parameters of the meta-heuristic algorithm were performed to ensure its adaptability to MTI problem-solving, followed by a comprehensive performance comparison of each algorithm. Subsequently, the optimization effects were scrutinized through fitness function values. The blasting and MS events were structurally interpreted. Outcomes of the study reveal that MFO outperforms other heuristic algorithms, achieving an impressive success rate (SR = 99 %) and reduced computation time (3.28 min) with a smaller number of population (NP = 40) and number of iterations (NG = 60). The median fitness values for MFO-MTI in the case of MS data and blasting data were 0.257 and 0.118, respectively, significantly surpassing non-optimized results (0.497 and 0.219). Through the analysis of focal mechanism, the average strike and dip of MS events are 17.41° and 71.11°, which are basically consistent with the fault strike (7–25°) and dip (75–85°) on the east side of the mining area. In summary, this research contributes a systematic approach to enhance seismic MTI, demonstrating the superior efficacy of MFO in optimizing focal mechanism, particularly in the context of mining-induced seismicity.