When the Earth shakes, the impact doesn’t stop at the surface. New research reveals that powerful earthquakes can send shockwaves all the way into space, disrupting satellite signals and GPS systems by disturbing the charged upper layers of our atmosphere.
Scientists from Nagoya University in Japan have made the first 3D visualisation of how the atmosphere reacted to a powerful 7.5-magnitude earthquake that hit the Noto Peninsula on 1 January 2024. They used data from over 4,500 Global Navigation Satellite System (GNSS) receivers across Japan.
Their research, published in the journal Earth, Planets and Space, shows how earthquakes can send complex sound waves into the upper atmosphere, disturbing a layer called the ionosphere. These disturbances can affect satellite communications and GPS signals, and challenge what scientists previously believed about how these waves travel.
What is the Ionosphere, and why does it matter?
The ionosphere is a part of the atmosphere that lies 60 to 1,000 kilometres above the Earth. It’s filled with charged particles and plays an important role in sending radio signals from satellites to the ground.
When the earthquake happened, it created sound waves that travelled upward into the ionosphere. These waves changed the amount of charged particles, which slowed down satellite signals. By measuring the delays in these signals, the researchers were able to calculate these changes and use a technique similar to a medical CT scan to build 3D images of the disturbances.
Surprising patterns in the sky
About 10 minutes after the earthquake, wave-like ripples appeared in the ionosphere, similar to the way water ripples after a stone is dropped in a pond. However, the team noticed something unusual – some of the waves tilted in a strange direction, south of the earthquake’s epicentre, and slowly straightened out as they rose higher.
Old models, which assumed that these waves came from a single point, couldn’t explain this pattern.
The breakthrough came when the scientists considered that the earthquake didn’t rupture in one spot, but along a 150-kilometre fault line. Dr Weizheng Fu, the lead author, said, “Earthquakes don’t rupture at one point, but spread along faults.” Their updated model showed that the sound waves were created at different places along the fault, around 30 seconds apart. This matched what they observed in the sky.
Why does this matter for technology and safety?
