白银地区矿震波形特征及其震源机制求解

Seismic Waveform Characteristics and Focal Mechanism Solutions of Mining-Induced Earthquakes in the Baiyin Area

摘要: 甘肃省白银市地震活动性存在明显的空间分异特征：白银区因矿产资源集中开采而矿震活动显著，平川区则因远离矿区、构造独立而以天然构造地震为主。为准确识别矿震的典型特征，本文基于区域地震台网数据，采用空间对比分析与波形反演方法，系统对比了震级相近条件下白银区矿震与平川区天然地震的波形差异，并反演了白银区矿震的震源机制解。同时，结合自主研发的多种分析程序(包括空间分布可视化、波形时频分析、震级–时序分析与$b$ 值计算等)，实现了从空间分布、时间序列到波形频谱的多维度定量对比。结果表明，与天然地震相比，矿震在时域上呈现持续时间短、衰减快的特点，在频域上则表现为优势频率高、频带较宽的特征。震源机制解显示，白银区矿震破裂机制复杂，以走滑型、正断层型及伴随显著非双力偶(体积收缩)分量的塌陷型为主，其空间分布与采空区及开采活动密切相关。$b$ 值分析表明，矿震的$b$ 值(平均1.2)显著低于天然地震(平均1.8)，反映矿震活动具有大震级事件相对偏多的特征。上述多维度特征构成了矿震识别的可靠证据链，对矿山灾害防控具有重要应用价值。

Abstract: The seismic activity in Baiyin City, Gansu Province, exhibits significant spatial differentiation: the Baiyin District, characterized by concentrated mineral resource extraction, shows pronounced mining-induced earthquake activity, whereas the Pingchuan District, located far from mining areas with an independent tectonic setting, is dominated by natural tectonic earthquakes. To accurately identify the typical characteristics of mining-induced earthquakes, this study utilizes data from the regional seismic network. Employing spatial comparative analysis and waveform inversion methods, it systematically compares the waveform differences between mining-induced earthquakes in the Baiyin District and natural earthquakes in the Pingchuan District under similar magnitudes, and inverts the focal mechanism solutions of mining-induced earthquakes in the Baiyin District. Furthermore, combined with self-developed analytical programs (including spatial distribution visualization, waveform time-frequency analysis, magnitude-time series analysis, and $b$ -value calculation), a multi-dimensional quantitative comparison is achieved across spatial distribution, temporal sequence, and waveform spectrum. The results indicate that compared to natural earthquakes, mining-induced earthquakes exhibit shorter duration and faster attenuation in the time domain, and are characterized by higher dominant frequencies and a wider frequency band in the frequency domain. Focal mechanism solutions reveal that the rupture mechanisms of mining-induced earthquakes in the Baiyin District are complex, primarily dominated by strike-slip, normal faulting, and collapse types accompanied by significant non-double-couple (volume contraction) components. Their spatial distribution is closely related to goaf areas and mining activities. $b$ -value analysis shows that the $b$ -value for mining-induced earthquakes (average 1.2) is significantly lower than that for natural earthquakes (average 1.8), reflecting a characteristic of relatively more large-magnitude events in mining-induced seismic activity. The multi-dimensional characteristics mentioned above constitute a reliable chain of evidence for identifying mining-induced earthquakes and hold significant application value for mine disaster prevention and control.