On January 12, 2022, at 4.47 pm, the Hunga Tonga – Hunga Ha’apai (HTHH) volcano erupted violently for 11 hours. This was the biggest eruption seen worldwide in 140 years, and the first with such a wide array of measuring instruments available. Scientists have pored over the data and now have a better understanding of the processes involved. NZASE’s Mike Stone adds to last year’s article with what we now know.