University of Oxford: Tonga volcano eruption triggered atmospheric gravity waves that reached the edge of space

The eruption of the Hunga Tonga-Hunga Ha’apai submarine volcano in January 2022 was one of the most explosive volcanic events of the modern era, a new study has confirmed.

A multi-institutional international team of researchers combined extensive satellite data with ground-level observations to show that the eruption was unique in observed science in both its magnitude and speed, and in the range of the fast-moving gravity and atmospheric waves it created.

Following a series of smaller volcanic events beginning in December 2021, Hunga Tonga erupted on 15 January this year, producing a vertical plume that extended more than 50km above the Earth’s surface.

The heat released from the water and hot ash in the plume was the most significant source of gravity waves on Earth for the following 12 hours. The eruption produced ripple-like gravity waves that satellite observations show extended across the Pacific basin.

Co-author Dr Scott Osprey, Department of Physics, University of Oxford advised that there could be further impacts from the Hunga Tonga eruption:

‘Our study nicely shows how the striking display of global waves was driven by the huge amounts of seawater vaporised during the eruption. However, my gut feeling is that there is more to come from this eruption. As the exceptional amount of water vapour spreads throughout the stratosphere, eyes will turn to the Antarctic ozone hole and just how severe it will be in the spring.’

The eruption also triggered waves in the atmosphere that reverberated around the planet at least six times and reached close to their theoretical maximum speeds – at 320m per second or 720 miles per hour.

The fact that a single event dominated such a large region is described by the paper’s authors as unique in the observational climate record, and one that will help scientists improve future atmospheric weather and climate models.

Lead author Dr Corwin Wright, Centre for Space, Atmospheric and Oceanic Science at the University of Bath said:

‘This was a genuinely huge explosion, and truly unique in terms of what’s been observed by science to date. We’ve never seen atmospheric waves going around the whole world before, or at this speed – they were travelling very close to the theoretical limit.

‘The eruption was an amazing natural experiment. The data we’ve been able to gather on it will enhance our understanding of our atmosphere and will help us improve our weather and climate models.’

University of Oxford