Hunga Tonga volcanic explosion

On 15th January 2022, at 04:15 UTC (05:15 CET, 17:15 local time) a huge volcanic explosion was detected on the Hunga Tonga–Hunga Haʻapai island took place in the Tonga archipelago, where an eruption was ongoing. The explosion was so strong that it destroyed the island almost completely, and generated an atmospheric shock wave that swept across the whole Earth.

Almost sixteen hours later, the shock wave was detected in Europe, around 20:00 UTC as a "ripple" in the atmospheric pressure readings of about 3 hPa total amplitude, that lasted about 45 min. Actually there was a second, smaller (1.5 hPa) ripple about five hours later, at 2 am local time, that lasted about half an hour.

The presence of two ripples can be easily explained by considering than when the explosion occurred, a circular shock wave was generated. This shock wave traveled around the globe along two different paths, one westbound and one eastbound. The westbound wavefront traveled about 17300 km, while the eastbound one traveled a longer distance (around 22700 km). Therefore, the eastbound wavewront arrived later, and noticeably attenuated.

Below are three images: a Facebook announcement by Albino Carbognani, an Italian astronomer, and the pressure plots of two personal weather station, one belonging to me and one to my good frienda and fellow amateur astronomer Lorenzo Comolli. Both weather stations are located in Northern Italy, about 50 km Northwest of Milan. The ripples from the two wavefronts are circled in red.

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Hunga-Tonga Eruption of 15th January 2022 - Pressure wave detected in Europe

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Hunga-Tonga Eruption of 15th January 2022 - Pressure wave detected in Europe

Hunga-Tonga Eruption of 15th January 2022 - Pressure wave detected in Europe

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Hunga-Tonga Eruption of 15th January 2022 - Pressure wave detected in Europe

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