The Oruanui eruption of New Zealand'sTaupo Volcano, the world's most recentsupereruption, had a Volcanic Explosivity Index of 8. It is one of the largest eruptions in the history of New Zealand. It occurred about 26,500 years ago in the Late Pleistocene and generated approximately of pyroclastic fall deposits, of pyroclastic density current deposits and of primary intracaldera material, equivalent to of magma, totaling of total deposits. The eruption is divided into 10 different phases on the basis of nine mappable fall units and a tenth, poorly preserved but volumetrically dominant fall unit. Modern-day Lake Taupo partly fills the caldera generated during this eruption. A structural collapse is concealed beneath Lake Taupo, while the lake outline at least partly reflects volcano-tectonic collapse. Early eruption phases saw shifting vent positions; development of the caldera to its maximum extent occurred during phase 10. The Oruanui eruption shows many unusual features: its episodicnature, wide range of magma-water interaction, and complex interplay of pyroclastic fall and flow deposits. As the eruption occurred through a lake system overlying the vent, many of the deposits contain volcanic ash aggregates. from the Oruanui eruption, containing spherical accretionary lapilli Tephra from the eruption covered much of the central North Island, with ignimbrite up to deep. Ashfall affected most of New Zealand, with an ash layer as thick as deposited on the Chatham Islands, away. Later erosion and sedimentation had long-lasting effects on the landscape, and may have caused the Waikato River to shift from the Hauraki Plains to its current course through the Waikato to the Tasman Sea. Less than 22,500 years ago, Lake Taupo, having filled to about above its current level, cut through its Oruanui ignimbrite dam at a rate which left no terraces around the lake. About of water was released, leaving boulders of up to at least as far down the Waikato River as Mangakino.
