Sensitivity Analysis of a SAR Model for Microseismic Monitoring in the Three Gorges Reservoir Area
摘要
This study evaluates the SAR model, combining RNN, GRU, and multi-head attention mechanisms, for microseismic phase picking using 87,050 three-component waveforms from the Three Gorges Reservoir area (2017–2020). Data preprocessing involved bandpass filtering (2–40 Hz) and phase association via the PAL method. Parameter optimization yielded a learning rate of 1×10−4, 15 epochs, and a single attention head. The optimized model achieved P- and S-wave arrival-time errors of 0.68 s and 1.28 s, respectively, with greater than 92% valid picks within 2σ. Compared to the PAL method, it reduced the mean residual to 0.12 s. The SAR-derived catalog detected 3,022 events (3 times more than the network catalog) while maintaining a consistent completeness magnitude (Mc0.8) and identifying previously undetected shallow events (0–5 km) aligned with fault zones.