Researchers have learned to warn of a tsunami using GPS satellites

The created system analyzes changes in the ionosphere using data from existing GPS satellites.

The results showed that tsunamis lead toa decrease in the electron density at an altitude of 300 km above this region. This, in turn, affects the radio signals sent by GPS satellites to ground receivers, delaying or speeding up various parts of the signal, or changing its direction depending on the frequency.

The researchers found that the acoustic wave,caused by the initial rise in water, it took about seven minutes to reach the 300 km altitude in the ionosphere, and the resulting decrease in electron density could be detected using satellite signals in 10–15 minutes.

“Existing tsunami warning systems do notare as efficient as they should be, as they often cannot accurately predict wave height,” says Prof. Serge Guillas, senior author on the paper. "Our study, a collaborative effort between statisticians and space scientists, demonstrates a novel tsunami detection method that is inexpensive because it relies on existing GPS networks and can be implemented worldwide, complementing other tsunami detection methods and improving their accuracy."

An international team of scientists analyzed withGPS data from the devastating 2011 Tohoku-Oki earthquake and resulting tsunami using their method. The results showed that a tsunami warning could have been issued within 15 minutes of the earthquake, i.e. at least 10 minutes before the first wave hit the east coast of Japan.

“With the help of the analysis of changes in the ionosphere, one can notonly predict the tsunami, but infer the size and shape of the wave. The next step in the study will be to explore this further to see if this method can be used to more accurately predict the size and scale of a tsunami. Based on my experience working for the Japanese government in the past and observing the damage caused by the tsunami, I believe that if this study is carried out, it will undoubtedly contribute to saving lives,” hopes lead author and PhD Ryuichi Kanai.

Many systems in existence today canwarn of tsunamis caused by earthquakes. According to the researchers, the new method can be used to predict upcoming tsunamis, the sources of which are landslides and volcanic eruptions.

Although some tsunamis reach the coast less thanthan 10 minutes, the researchers noted that the developed system could also be used to predict a second or third wave, helping to determine whether a tsunami warning should be canceled or maintained after the first wave.

The ionosphere is the upper part of the atmosphere, saturated with ions and free electrons. It extends from 48 to 965 km above the Earth's surface.

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