According to a new study, the January 15 eruption of the Tonga volcano was one of the most explosive volcanic events of the modern era, creating waves that reverberated around the earth and reached 100 km into the ionosphere.
The Hunga Tonga eruption produced a vertical plume that extended more than 50 kilometres above the earth’s surface.
For the next 12 hours, the heat released by the water and hot ash in the plume remained the most powerful source of gravity waves on Earth. The eruption also generated ripple-like gravity waves that, according to satellite observations, extended across the Pacific basin.
The eruption also caused waves in the atmosphere to reverberate six times around the planet, reaching close to their theoretical maximum speeds – the fastest ever seen within our atmosphere, at 320 m per second, according to researchers from the University of Bath in the United Kingdom.
“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 round the whole world before, or at this speed – they were travelling very close to the theoretical limit,” Dr Corwin Wright, a Royal Society University Research Fellow based at the Centre for Space, Atmospheric and Oceanic Science at the University.
“Our study nicely shows how the striking display of global waves is 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,” added Dr Scott Osprey from the National Centre for Atmospheric Science, at University of Oxford.
The study combined extensive satellite data with ground-level observations to demonstrate that the eruption was unprecedented in terms of magnitude and speed, as well as the range of the fast-moving gravity and atmospheric waves it produced.
The team wrote in the journal Nature that the fact that a single event dominated such a large region is unique and will help scientists improve future atmospheric weather and climate models.
