Constraining S-wave velocity using Rayleigh wave ellipticity from polarization analysis of seismic noise
Constraining S-wave velocity using Rayleigh wave ellipticity from polarization analysis of seismic noise
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DOI：
10.1093/gji/ggy512
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发表时间：
2019-03-01
影响因子：
2.8
通讯作者：
Morelli, Andrea
中科院分区：
文献类型：
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作者：
Berbellini, Andrea;Schimmel, Martin;Morelli, Andrea
我们开发了一种新方法，通过偏振度 (DOP) 分析来测量环境噪声记录中瑞利波的椭圆率。这种名为 DOP-E 的新方法显示出检索与非相干噪声分离的准确椭圆率曲线的良好能力。为了验证该方法，我们在一维地球模型中进行了模拟噪声的综合测试。我们还对来自南极洲和意大利北部的真实数据进行测量。观测到的曲线与地震记录的测量值和理论椭圆率曲线非常吻合。 v(S) 结构的实际数据测量结果的反演显示出与之前模型的良好一致性。特别是，康科迪亚站下方的剪切波结构没有显示冰底部存在大量液态水的证据。新方法可用于测量高频椭圆率，因此它将允许对近地表结构进行成像，并可能对地下特性的时间变化进行成像。它有望有助于研究火山、断层带和冰川等各种地质环境中的近地表过程。
We develop a new method for measuring ellipticity of Rayleigh waves from ambient noise records by degree-of-polarization (DOP) analysis. The new method, named DOP-E, shows a good capability to retrieve accurate ellipticity curves separated from incoherent noise. In order to validate the method we perform synthetic tests simulating noise in a 1-D earth model. We also perform measurements on real data from Antarctica and Northern Italy. Observed curves show a good fit with measurements from earthquake records and with theoretical ellipticity curves. The inversion of real data measurements for v(S) structure shows a good agreement with previous models. In particular, the shear-wave structure beneath Concordia station shows no evidence of a significant layer of liquid water at the base of the ice. The new method can be used to measure ellipticity at high frequency and therefore it will allow the imaging of near-surface structure, and possibly of temporal changes in subsurface properties. It promises to be useful to study near-surface processes in a wide range of geological settings, such as volcanoes, fault zones and glaciers.