SKS Polarization Anomalies Due to the Coriolis Force
SKS Polarization Anomalies Due to the Coriolis Force
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DOI：
10.1785/0120230125
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发表时间：
2023-10
影响因子：
3
通讯作者：
N. Creasy;Ebru Bozdağ;Daniel A. Frost;Roel Snieder
中科院分区：
文献类型：
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作者：
N. Creasy;Ebru Bozdağ;Daniel A. Frost;Roel Snieder
众所周知，地球的科里奥利力会影响表面波和简正波，这对于准确解释这些波是必不可少的。然而，科里奥利力的体波已被假定为可以忽略不计，大多数被忽略。先前已经表明，科里奥利力影响剪切波的偏振，而波前保持不受影响。我们扩大对剪切波偏振测量地球的科里奥利力的潜在影响进行三维数值模拟地震和爆炸源产生的弹性波在径向对称，三维地幔和地壳模型。科里奥利力可使地幔剪切波偏振异常达7 °，核震相SKS和SKKS偏振异常达4 °。由于科里奥利力引起的未校正的剪切波偏振会导致额外的误差源（快方向5 °-10 °，延迟时间0.2 - 0.3 s，取决于方法和地震相位），对台站未对准的不准确解释，以及对核幔边界地形的不精确估计。我们展示了如何使用一维射线追踪良好的隔离相位校正Coriolis力对Escherichia剪切波。我们建议使用全波形模拟来准确地解释地震源参数、在测量时间窗口内可能包括干扰相位到达的隔离不良相位以及科里奥利力对剪切波偏振的影响。
The Earth’s Coriolis force has been well-known to impact surface waves and normal modes, which is essential to accurately interpret these waves. However, the Coriolis force on body waves has been assumed to be negligible and mostly ignored. It has been previously shown that the Coriolis force impacts polarizations of shear waves, whereas the wavefronts remain unaffected. We expand on the potential influences of Earth’s Coriolis force on shear-wave polarization measurements by conducting 3D numerical simulations for elastic waves generated by earthquake and explosive sources in a radially symmetric, and 3D mantle and crustal models. The Coriolis force can produce polarization anomalies of mantle shear waves up to 7° and core phases, such as SKS and SKKS, up to 4°. Uncorrected shear-wave polarizations due to the Coriolis force can cause an additional source of error (5°–10° in fast direction, and 0.2–0.3 s delay time depending on the method and seismic phase), inaccurate interpretation of station misalignments, and imprecise estimates of the core–mantle boundary topography. We show how to correct for the Coriolis force on teleseismic shear waves using 1D ray tracing for well-isolated phases. We recommend the use of full waveform simulations to accurately account for earthquake sources parameters, poorly isolated phases that could include interfering phase arrivals within the measurement time window, and the effect of the Coriolis force on the polarizations of shear waves.