Several later eruptions occurred over the millennia before the most recent major eruption, which is traditionally dated as about 181 CE from Greenland ice-core records. Tree ring data from two studies suggests a later date of 232 CE ± 5. Known as the Hatepe eruption, it is believed to have ejected 100 cubic kilometres of material, of which 30 cubic kilometres was ejected in a few minutes. This was one of the most violent eruptions in the last 5000 years (alongside the Minoan eruption in the 2nd millennium BCE, the Tianchi eruption of Baekdu around 1000 CE and the 1815 eruption of Tambora), with a Volcanic Explosivity Index rating of 7; and there appears to be a correlation, to within a few years, of a year in which the sky was red over Rome and China. The eruption devastated much of the North Island and further expanded the lake. The area was uninhabited by humans at the time of the eruption since New Zealand was not settled by the Māori until about 1280. Possible climatic effects of the eruption would have been concentrated on the southern hemisphere due to the southerly position of Lake Taupo. Taupo's last known eruption occurred around 30 years later, with lava dome extrusion forming the Horomatangi Reefs, but that eruption was much smaller than the 180 CE eruption.