The problem of the relationship of the properties of seismic noise with the irregular rotation of the Earth is considered. We study the median daily values of the multifractal singularity spectrum support width, the generalized Hurst exponent, and the seismic noise wavelet-based entropy on the networks of broadband seismic stations in Japan and California for the time interval 1997–2019. The first principal components of the noise properties in a half year moving time window are calculated. The coherence spectra are estimated both between the principal noise components in two regions and each principal component with a time series of the length of day (LOD). It has been shown that an increase in the power of high-frequency pulsations of LOD (for periods less than 6 days) is accompanied by a decrease in the coherence between the properties of seismic noise in Japan and California. The degree of synchronization of the response of changes in the properties of seismic noise in Japan and California to the irregularity of Earth’s rotation in a “long” moving time window of 5 years is estimated. For this purpose, the correlation coefficient and the “secondary” coherence spectrum between synchronous variations of the “primary” coherence spectra between the LOD and each of the main noise components obtained in the “short” half-year window, as well as their mutual correlation function, were calculated.

中文翻译：

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日本和加利福尼亚地震噪声特性与地球自转不规则性的联系

考虑了地震噪声特性与地球不规则自转的关系问题。我们研究了 1997-2019 年日本和加利福尼亚宽带地震台站网络上多重分形奇异性谱支持宽度、广义 Hurst 指数和基于地震噪声小波的熵的每日中值。计算半年移动时间窗口中噪声特性的第一主成分。相干谱是在两个区域的主要噪声分量之间以及每个主要分量与一天的长度 (LOD) 的时间序列之间估计的。已经表明，LOD 的高频脉动功率的增加（周期少于 6 天）伴随着日本和加利福尼亚地震噪声特性之间相干性的降低。估计了日本和加利福尼亚地震噪声特性变化对地球自转不规则性在 5 年“长”移动时间窗口内的响应同步程度。为此，在 LOD 与“短”半年窗口中获得的每个主要噪声分量之间的“主要”相干谱的同步变化之间的相关系数和“次要”相干谱，以及它们的相互相关函数，进行了计算。估计了日本和加利福尼亚地震噪声特性变化对地球自转不规则性在 5 年“长”移动时间窗口内的响应同步程度。为此，在 LOD 与“短”半年窗口中获得的每个主要噪声分量之间的“主要”相干谱的同步变化之间的相关系数和“次要”相干谱，以及它们的相互相关函数，进行了计算。估计了日本和加利福尼亚地震噪声特性变化对地球自转不规则性在 5 年“长”移动时间窗口内的响应同步程度。为此，在 LOD 与“短”半年窗口中获得的每个主要噪声分量之间的“主要”相干谱的同步变化之间的相关系数和“次要”相干谱，以及它们的相互相关函数，进行了计算。