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The eruption of the Tonga's Hunga volcano in January has been confirmed as the biggest explosion ever recorded in the atmosphere by modern instrumentation.
It was far bigger than any 20th century volcanic event, or indeed any atom bomb test conducted after WWII.
Scientists involved in the study published in the journal Science say the eruption was a "truly global event" of similar scale to the 1883 Krakatoa eruption in Indonesia.
GNS Science senior volcanologist Dr Geoff Kilgour was one of the authors on the paper.