We propose a new waveform inversion method to estimate the 2D S-wave velocity structure of deep sedimentary layers using broadband Love waves. As a preprocessing operation in our inversion scheme, we decompose earthquake observation records into velocity waveforms for periods of 1 s each. Then, we include in the inversion only those periods for which the assumption of 2D propagation holds, which we propose to determine through a principal component analysis. A linearized iterative inversion analysis for the selected Love wave segments filtered for periods of 1 s each allows a detailed estimation of the boundary shapes of interfaces over the seismic bedrock with an S-wave velocity of approximately 3 km/s. We demonstrate the effectiveness of the technique with applications to observed seismograms in the Kanto Plain, Japan. The differences between the estimated and existing velocity structure models are remarkable at the basin edges. Our results show remarkable differences from previous existing structural models, particularly near the basin edges while being in good agreement with the surface geology. Since a subsurface structure at a basin edge strongly affects the earthquake ground motions in a basin with the generation of surface waves, our method can provide a detailed model of a complex S-wave velocity structure at an edge part for strong ground motion prediction.

中文翻译：

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深沉积层二维横波速度模型地震地震动记录中Love波的反演

我们提出了一种新的波形反演方法，利用宽带洛夫波估计深沉积层的二维 S 波速度结构。作为我们反演方案中的预处理操作，我们将地震观测记录分解为每个周期为 1 秒的速度波形。然后，我们在反演中只包括那些 2D 传播假设成立的时期，我们建议通过主成分分析来确定这些时期。对每个过滤周期为 1 s 的所选 Love 波段进行线性化迭代反演分析，可以详细估计地震基岩上界面的边界形状，其中 S 波速度约为 3 km/s。我们通过应用到日本关东平原观测到的地震图来证明该技术的有效性。在盆地边缘，估计的和现有的速度结构模型之间的差异是显着的。我们的结果显示出与先前现有结构模型的显着差异，特别是在盆地边缘附近，同时与地表地质非常吻合。由于盆地边缘的地下结构强烈影响盆地内地震地面运动并产生面波，我们的方法可以为强地震动预测提供边缘部分复杂S波速度结构的详细模型。