'How did this happen?': Scientists gobsmacked by new data from Tonga volcano eruption

When the underwater volcano Hunga Tonga-Hunga Ha'apai erupted in January 2022, scientists knew something extraordinary had happened. An ash plume shot 57 kilometres into the atmosphere; shock waves rippled through the atmosphere, and the eruption triggered a tsunami that reached heights of more than 19 metres above sea level. But masked by the waters of the Pacific Ocean, what happened beneath the