0–5 Hz deterministic 3-D ground motion simulations for the 2014 La Habra, California, Earthquake
0–5 Hz deterministic 3-D ground motion simulations for the 2014 La Habra, California, Earthquake
复制标题
2014 年加利福尼亚州拉哈布拉地震的 0–5 Hz 确定性 3D 地面运动模拟
DOI：
10.1093/gji/ggac174
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发表时间：
2022
影响因子：
2.8
通讯作者：
Day, Steven M.
中科院分区：
文献类型：
--
作者：
Hu, Zhifeng;Olsen, Kim B.;Day, Steven M.
我们使用有限断层震源，使用南加州地震中心社区速度模型版本S4.26-M01，模拟了2014年加利福尼亚州拉哈布拉5.1 Mw地震的一套17个模型的0-5 Hz确定性波传播。利用148 km × 140 km区域内259个观测点的强震动资料对模拟结果进行了验证。我们的模拟量化了小尺度地壳非均匀性（SSHs），频率相关衰减Q（f），表面地形和近地表低速材料（通过1-D近似）的统计分布对所产生的地面运动合成的影响。对于频率小于和高于1 Hz的情况，横波品质因数QS（f）分别被参数化为QS，0和QS，0 f γ。我们发现，对于QS，0与剪切波速度VS之比为0.075-1.0且γ值小于0.6的模型，最适合于数据，对于γ值为0.2-0.4的较高频率，最适合的振幅下降。包括地形和真实的近地表风化层的模型往往会增加山峰和山脊处的峰值速度，而在波传播方向上，山峰和山脊后面的峰值速度相应降低。我们发现峰值地面速度放大和持续时间延长的影响之间存在明显的负相关性，这表明地形重新分配地震能量从大振幅的初至相邻的尾波。现实的近地表低速度的风化层被发现，以提高放大在山峰和山脊，并可能部分解释预测不足的地形对地面运动的影响模型中发现。与具有平坦自由表面的模型相比，我们的模型（包括地形）倾向于改善与数据的拟合，而我们的SSHS分布与钻孔数据的约束未能显着改善拟合。速度模型的准确性，特别是近地表的低速度，以及源的描述，控制的分辨率与滞弹性衰减可以确定。我们的研究结果表明，它是可行的，使用完全确定性的物理为基础的模拟估计地面运动的地震危险性分析高达5赫兹。在这里，随着频率向5 Hz增加，近地表低速物质、地形、SSH和Q（f）的影响和权衡变得越来越重要，并且应该包括在计算中。未来社区速度模型的改进，更广泛的计算资源，更有效的数值代码和指导，从这项研究必将进一步限制地面运动模型，导致更准确的地震危险性分析。
We have simulated 0–5 Hz deterministic wave propagation for a suite of 17 models of the 2014Mw5.1 La Habra, CA, earthquake with the Southern California Earthquake Center Community Velocity Model Version S4.26-M01 using a finite-fault source. Strong motion data at 259 sites within a 148 km × 140 km area are used to validate our simulations. Our simulations quantify the effects of statistical distributions of small-scale crustal heterogeneities (SSHs), frequency-dependent attenuationQ(f), surface topography and near-surface low-velocity material (via a 1-D approximation) on the resulting ground motion synthetics. The shear wave quality factorQS(f) is parametrized asQS, 0andQS, 0fγfor frequencies less than and higher than 1 Hz, respectively. We find the most favourable fit to data for models using ratios ofQS, 0to shear wave velocityVSof 0.075–1.0 and γ values less than 0.6, with the best-fitting amplitude drop-off for the higher frequencies obtained for γ values of 0.2–0.4. Models including topography and a realistic near-surface weathering layer tend to increase peak velocities at mountain peaks and ridges, with a corresponding decrease behind the peaks and ridges in the direction of wave propagation. We find a clear negative correlation between the effects on peak ground velocity amplification and duration lengthening, suggesting that topography redistributes seismic energy from the large-amplitude first arrivals to the adjacent coda waves. A weathering layer with realistic near-surface low velocities is found to enhance the amplification at mountain peaks and ridges, and may partly explain the underprediction of the effects of topography on ground motions found in models. Our models including topography tend to improve the fit to data, as compared to models with a flat free surface, while our distributions of SSHs with constraints from borehole data fail to significantly improve the fit. Accuracy of the velocity model, particularly the near-surface low velocities, as well as the source description, controls the resolution with which the anelastic attenuation can be determined. Our results demonstrate that it is feasible to use fully deterministic physics-based simulations to estimate ground motions for seismic hazard analysis up to 5 Hz. Here, the effects of, and trade-offs with, near-surface low-velocity material, topography, SSHs andQ(f) become increasingly important as frequencies increase towards 5 Hz, and should be included in the calculations. Future improvement in community velocity models, wider access to computational resources, more efficient numerical codes and guidance from this study are bound to further constrain the ground motion models, leading to more accurate seismic hazard analysis.