The 15 January 2022, eruption at Hunga Tonga-Hunga Ha'apai (HTHH) volcano started shortly after 4:00UTC. There had been noted unconfirmed precursory events. We analyzed seismometer data recorded in Fiji and Futuna, the closest stations operated during the eruption and located over 750 km away. We extracted Rayleigh waves and estimated their powers and source directions, assuming retrograde particle motions. We found a Rayleigh wave from the HTHH's direction about 15 min before the eruption onset. The arrival time difference of the Rayleigh wave between the two stations was consistent with that of the M5.8 earthquake during the eruption located beneath the HTHH. Referring to other seismic signals and satellite images, we concluded that the Rayleigh wave was the most significant eruption precursor with no apparent surface activity. Including our findings and results of previous studies, we propose a scenario of the beginning of the caldera-forming eruption.

中文翻译：

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2022 年 1 月 15 日汤加-洪加哈阿帕伊火山大喷发前 15 分钟的地震前兆


2022 年 1 月 15 日，Hunga Tonga-Hunga Ha'apai （HTHH） 火山在 4：00UTC 后不久开始喷发。已经注意到未经证实的前兆事件。我们分析了斐济和富图纳群岛记录的地震仪数据，这是火山喷发期间运营的最近的地震站，距离酒店 750 多公里。我们提取了瑞利波，并估计了它们的功率和源方向，假设粒子运动逆行。我们在喷发开始前约 15 分钟发现了来自 HTHH 方向的瑞利波。两个站点之间瑞利波的到达时间差与位于 HTHH 下方的喷发期间 M5.8 地震的到达时间差一致。参考其他地震信号和卫星图像，我们得出结论，瑞利波是最重要的喷发前兆，没有明显的表面活动。包括我们的发现和以前的研究结果，我们提出了破火山口形成喷发开始的情景。