Microseisms are the most ubiquitous continuous seismic signals on Earth at periods between approximately 5 and 25 s (Peterson 1993; Kedar and Webb 2005). They arise from atmospheric energy converted to (primarily) Rayleigh waves via the intermediary of wind-driven oceanic swell and occupy a period band that is uninfluenced by common anthropogenic and wind-coupled noise processes on land (Wilson et al. 2002; de la Torre et al. 2005). "Primary" microseisms (near 8-s period) are generated in shallow water by breaking waves near the shore and/or the nonlinear interaction of the ocean wave pressure signal with the sloping sea floor (Hasselmann 1963). Secondary microseisms occur at half of the primary period and are especially strongly radiated in source regions where opposing wave components interfere (Longuett-Higgins 1950; Tanimoto 2007), which principally occurs due to the interaction of incident swell and reflected/scattered wave energy from coasts (Bromirski and Duennebier 2002; Bromirski, Duennebier, and Stephen 2005). Coastal regions having a narrow shelf with irregular and rocky coastlines are known to be especially efficient at radiating secondary microseisms (Bromirski, Duennebier, and Stephen 2005; Shulte-Pelkum et al. 2004). The secondary microseism is globally dominant, and its amplitudes proportional to the square of the standing wave height (Longuett-Higgins 1950), which amplifies its sensitivity to large swell events (Astiz and Creager 1994; Webb 2006).
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机译：微地震是地球上最普遍的连续地震信号，大约在5到25秒之间（Peterson 1993; Kedar和Webb 2005）。它们来自大气能，它们是通过风驱动的海浪膨胀转换为（主要是）瑞利波的，并且占据了一个周期带，不受陆地上常见的人为和风耦合噪声过程的影响（Wilson等，2002; de la Torre）等（2005）。通过在海岸附近破坏海浪和/或海浪压力信号与倾斜的海床之间的非线性相互作用，在浅水中产生“原始”微震（接近8s周期）（Hasselmann 1963）。次生微震发生在初生期的一半，尤其在强烈的辐射作用下，对向的波分量产生干扰（Longuett-Higgins 1950; Tanimoto 2007），这主要是由于入射波和海岸反射/散射波能的相互作用所致。 （Bromirski和Duennebier 2002; Bromirski，Duennebier和Stephen 2005）。众所周知，具有狭窄陆架，不规则和多岩石海岸线的沿海地区在辐射次级微地震方面特别有效（Bromirski，Duennebier和Stephen 2005; Shulte-Pelkum等人2004）。次生微地震在全球占主导地位，其振幅与驻波高度的平方成正比（Longuett-Higgins，1950年），从而放大了其对大范围膨胀事件的敏感性（Astiz和Creager，1994年; Webb，2006年）。
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