Estimate of Rayleigh‐to‐Love wave ratio in the secondary microseism by colocated ring laser and seismograph
Estimate of Rayleigh‐to‐Love wave ratio in the secondary microseism by colocated ring laser and seismograph
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DOI：
10.1002/2015gl063637
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发表时间：
2015-04
影响因子：
5.2
通讯作者：
T. Tanimoto;C. Hadziioannou;H. Igel;J. Wasserman;U. Schreiber;A. Gebauer
中科院分区：
文献类型：
--
作者：
T. Tanimoto;C. Hadziioannou;H. Igel;J. Wasserman;U. Schreiber;A. Gebauer
使用一个共定位的环形激光器和一个STS-2地震仪，我们估计的瑞利-洛夫波在二次微震在德国，频率在0.13和0.30赫兹之间的比率。瑞利波表面加速度来自STS-2的垂直分量，乐甫波表面加速度来自环形激光器。表面波振幅相当;在频谱峰值约0.22 Hz附近，瑞利波振幅比乐甫波振幅高约20%，但在此范围之外，乐甫波振幅变得更高。在动能方面，瑞利波能量平均比勒夫波能量小约20-35%。因此，在Wettzell观测到的二次微震由可比较的瑞利波和Love波组成，但Love波的贡献更大。这是令人惊讶的，因为Longuet-Higgins（1950）描述的二次微震的唯一已知激发机制相当于垂直力，并且应该主要激发瑞利波。
Using a colocated ring laser and an STS‐2 seismograph, we estimate the ratio of Rayleigh‐to‐Love waves in the secondary microseism at Wettzell, Germany, for frequencies between 0.13 and 0.30 Hz. Rayleigh wave surface acceleration was derived from the vertical component of STS‐2, and Love wave surface acceleration was derived from the ring laser. Surface wave amplitudes are comparable; near the spectral peak about 0.22 Hz, Rayleigh wave amplitudes are about 20% higher than Love wave amplitudes, but outside this range, Love wave amplitudes become higher. In terms of the kinetic energy, Rayleigh wave energy is about 20–35% smaller on average than Love wave energy. The observed secondary microseism at Wettzell thus consists of comparable Rayleigh and Love waves but contributions from Love waves are larger. This is surprising as the only known excitation mechanism for the secondary microseism, described by Longuet‐Higgins (1950), is equivalent to a vertical force and should mostly excite Rayleigh waves.