Microscale clues provide insight into cataclysmic Tongan volcanic eruption

Key Points
  • The intensely powerful and destructive Hunga blast was unlike previous events, It was a unique event in that scientists were able to capture the eruption with satellite imagery and other instruments.
  • The Hunga volcano started out with a flat upper surface to a depth of 150 metres before the eruption, which ejected at least 6.5 cubic kilometres of ash and rock and left a deep caldera 250 metres below sea level.
  • Electron microscopy revealed different concentrations of chemicals in the two types of magma that came together and mingled to form distinctive swirling bands in the samples. Infrared beamline analysis techniques provided crucial information about the diffusion of water in the tiny fragments.
  • The chilling effect of the water as the magma fragmented, the concentration of water and the chemical composition of the particles also provided clues about the depth at which the event occurred.

When the Tongan Hunga volcano erupted in January this year, it was a huge explosion with a mass ejection that reached more than 55 kilometres into the atmosphere, causing local fatalities and evacuations. The blast created significant tsunami waves in the Pacific Basin and generated pressure waves that encircled the globe.

Although not a significant inundation,  the impact of the tsunami reached Australia with waves of 82cm at the Gold Coast, 65cm at Port Kembla and 77cm at Eden’s Twofold Bay in NSW.

In an effort to understand why the eruption was so explosive, internationally-recognised volcanologist Prof. Shane Cronin of the University of Auckland and associates rely on beamlines at the Australian Synchrotron to support comprehensive research on the Hunga event.

Two sets of experiments have already been carried on the Imaging and Medical beamline and the Infrared Microspectroscopy beamline, while another investigation is scheduled for the X-ray fluorescence microscopy beamline.

Read more on the ANSTO website

Image: Undersea volcano