Tonga volcano: 'The biggest eruption recorded by instruments'
When the underwater volcano Hunga-Tonga Hunga-Haʻapai blew its top, it sent ash and water-vapour half-way to space, and generated tsunami waves across the globe. A survey by New Zealand and UK vessels has now fully mapped the area around the Pacific seamount. Dr Kevin Mackay, from the National Institute of Water and Atmospheric Research, describes what has been learnt. He was speaking to our science correspondent Jonathan Amos.
