Sat-nav trouble? Blame a volcano beneath the sea

IF YOUR sat-nav steers you to the wrong address, it may be that an underwater volcano on the other side of the world is to blame.

Japanese scientists have discovered that eruptions under the surface can trigger air pressure waves that create holes in the ionosphere, severely disrupting global positioning systems.

The ionosphere – a region of the Earth’s upper atmosphere – contains a dense layer of positively charged atoms and molecules that are crucial for reflecting and refracting radio waves used by satellites back to Earth.

When there are gaps in the ionosphere it can have a knock-on effect for GPS systems, causing delays and leaving them struggling to give correct locations.

In a new study published in the journal Scientific Reports, researchers found that the Tonga underwater volcano, which erupted in January 2022, sent out shockwaves powerful enough to blast holes into the ionosphere – disrupting satellite signals as far as Asia on the other side of the world.

Prof Atsuki Shinbori, of the Institute for Space-earth Environmental Research, at Nagoya University, said: “In the case of a large-scale event, such as the Tonga volcano eruption, observations have shown that a hole in the ionosphere can form even under conditions that are considered unlikely to occur under normal circumstances.

“Such cases have not been incorporated into space weather forecast models. This study will contribute to the prevention of satellite broadcasting and communication failures associated with ionospheric disturbances caused by earthquakes, volcanic eruptions, and other events.”

Scientists have noticed that GPS signals can go haywire when the ionosphere is disturbed, sometimes creating global positioning discrepancies of 65ft.

In 2018, a study showed that a Spacex Falcon 9 rocket caused sufficient shockwaves to punch a 500 mile hole in the ionosphere, knocking off GPS navigation by more than 3m.

The holes occur when shockwaves force the molecules apart, creating empty areas in the ionosphere and giving radio waves nothing to bounce off. A GPS receiver determines its own location by measuring the time it takes for a signal to arrive at its location from at least four satellites. But if the signal takes longer to return, the location data is off.