Tonga Volcano Eruption Shockwaves Reached Satellites, Study Reveals

When the Hunga Tonga-Hunga Ha’apai volcano erupted in January 2022, it wasn’t just an ordinary natural event, it sent shockwaves through parts of Earth’s atmosphere rarely disturbed by volcanoes. A new study has surprised scientists as it reveals just how far-reaching the effects really were, even influencing satellites in low Earth orbit. It has challenged some prior assumptions about these kinds of eruptions.

Researchers from the University of Science and Technology of China reported that the eruption launched material to astonishing heights, exceeding 50 kilometres (over 31 miles) above the Earth’s surface. “The extraordinary eruption of the Tonga volcano on 15 January 2022 lofted material to heights exceeding 50 km, marking the highest observed since the satellite era,” the study noted.

How the Tonga Volcano Shook Earth’s Upper Atmosphere

But the eruption’s true power reached far beyond the lower layers of the atmosphere. Scientists found that the explosion’s shockwaves extended into the thermosphere, which is a region that begins about 85 kilometres (53 miles) above Earth and stretches up to 600 kilometres (375 miles). This area is where many satellites orbit.

“Our recent investigation discovered the dramatic thermospheric responses at satellite altitudes,” the researchers wrote. Using data from the GRACE-FO satellites along with atmospheric models, the team explored how the eruption’s force managed to shake even this high-altitude layer.

Their analysis focused on two possible culprits: Lamb waves, known for their quick and low-frequency movements, and gravity waves (GWs), which form when buoyant forces try to restore atmospheric stability. The evidence pointed strongly towards secondary gravity waves as the main driver behind the observed atmospheric disturbances.

The study found that after the initial volcanic blast hurled material into the mesosphere (the layer between the stratosphere and thermosphere), it triggered the formation of these secondary gravity waves. These waves then spread around the globe, traveling upward to where satellites orbit.

“While approximately 25% of these waves in terms of magnitude could be attributed to Lamb waves, the primary contribution came from GWs,” the researchers explained. The secondary gravity waves, they added, aligned closely in both timing and intensity with the satellite measurements.

“The comparison between the simulations and observations suggests that the MESORAC-HIAMCM secondary GWs are consistent with GRACE-FO measured global-propagation thermospheric density disturbances in timing and amplitude,” the study also explained.

The findings highlight the extraordinary reach of the Tonga eruption, offering new insight into how powerful events on the surface can influence the very upper edges of our atmosphere. It is vital to know what risks are posed to a zone critical for global communication and navigation here on earth, and as our reliance on satellites grows, more studies are required.