SUMMARY Tsunamis are often modelled as surface gravity waves of incompressible homogenous water propagating over a rigid seafloor. Previous studies have noted that when computing long-period tsunamis travelling at trans-oceanic distances with dominant periods of thousands of seconds, we need to consider four factors that are not included in the surface gravity wave theory: compressibility of seawater, density stratification of oceans, elasticity of the Earth and gravitational potential change associated with the tsunami motion. However, their effects on short-period tsunamis with dominant periods below 1000 s have not been examined. Here, we investigate how the four factors influence short-period tsunamis. Theoretical analyses and 1-D simulations using phase speeds of different tsunami models indicate that the resultant phase delay of short-period tsunamis becomes apparent after ∼1000 km propagation, mainly because of the first three factors. We then introduce a new phase correction method for dispersive short-period tsunamis with consideration of period-dependent ray paths and apply it to a 2-D simulation of a short-period tsunami from a submarine volcanic earthquake near Japan in 2015. The correction of the traveltime of a synthetic waveform by including the four factors amounts to ∼40 s at a distant station 1430 km away from the source, whereas the effects of the four factors on the waveforms are negligibly small at stations < ∼500km from the source. The observed traveltime at the ocean bottom pressure (OBP) gauge with a sampling interval at 15 s of the distant station can be explained only when these factors are incorporated into synthetic waveforms, indicating the effects due to the four factors are detectable by high-sampling OBP gauges that are deployed over broad oceanic regions.

中文翻译：

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弹性地球上密度分层可压缩海洋中短周期海啸的相位延迟

总结 海啸通常被建模为在刚性海底传播的不可压缩均质水的表面重力波。以往的研究指出，在计算以数千秒为主导的跨洋距离的长周期海啸时，我们需要考虑表面重力波理论中未包含的四个因素：海水的可压缩性、海洋的密度分层，地球的弹性和与海啸运动相关的引力势变化。然而，它们对主导周期低于 1​​000 秒的短周期海啸的影响尚未得到检验。在这里，我们调查这四个因素如何影响短期海啸。使用不同海啸模型的相位速度进行的理论分析和一维模拟表明，短周期海啸的相位延迟在传播~1000 km 后变得明显，主要是由于前三个因素。然后，我们介绍了一种考虑周期相关射线路径的弥散短周期海啸的新相位校正方法，并将其应用于 2015 年日本附近海底火山地震的短周期海啸的二维模拟。在距离震源 1430 km 的遥远台站，包含这四个因素的合成波形的走时约为 40 s，而在台站 < 时，四个因素对波形的影响可以忽略不计。距源头约500公里。