On 15 January 2022, a massive underwater eruption occurred at the Hunga Tonga-Hunga Ha'apai Volcano. The plume reached the mesosphere, and the eruption excited a significant atmospheric Lamb wave, which forced the tsunami. The complicated tsunami waveforms due to ocean-atmosphere coupling prevented inferring the force history of the excitation. To address this, we analyze ocean surface gravity waves (OSWs) from 15 to 40 mHz, which are decoupled from the Lamb wave due to their slower phase velocities. Modeling these OSWs, we infer that the excitation started at 4:00 UTC with an amplitude of $10^{10}$ N and lasted for 5 hr, followed by a sub-event at 8:40 UTC. The observations suggest an initial blowout of seawater above the summit and a subsequent outflow that excited a tsunami below 5 mHz. The 2 hr delayed OSW excitation from 6 to 15 mHz may indicate seawater inflow into the crater.

中文翻译：

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2022 年 Hunga Tonga-Hunga Ha'apai 火山喷发激发的海洋表面重力波


2022 年 1 月 15 日，Hunga Tonga-Hunga Ha'apai 火山发生大规模水下喷发。羽流到达中间层，喷发激发了重要的大气兰姆波，从而引发了海啸。由于海洋-大气耦合引起的复杂海啸波形无法推断激励的力历史。为了解决这个问题，我们分析了 15 到 40 mHz 的海洋表面重力波 （OSW），由于相位速度较慢，这些波与兰姆波解耦。对这些 OSW 进行建模，我们推断激发从 4：00 UTC 开始，振幅为 $10^{10}$ N，持续了 5 小时，随后在 8：40 UTC 发生了一个子事件。观测结果表明，山顶上方的海水最初爆发，随后流出，引发了低于 5 mHz 的海啸。从 6 到 15 mHz 的 2 小时延迟 OSW 激发可能表明海水流入陨石坑。