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Algorithm and satellite network 'could give early warning of tsunamis'

Joseph Flaig

Devastation left after the 2011 Japan tsunami (Credit: iStock)
Devastation left after the 2011 Japan tsunami (Credit: iStock)

Scientists are using a new algorithm to analyse data from more than 100 satellites around the world, hoping to detect devastating tsunamis.

A team of scientists from Sapienza University in Rome and NASA’s Jet Propulsion Laboratory in California have created the algorithm, which could add to existing early warning systems. The approach, known as the Variometric Approach for Real-time Ionosphere Observation (Varion), uses observations from GPS and other satellite “constellations” to detect disturbances in the Earth’s ionosphere, a layer of atmosphere between 50 and 621miles from the surface.

When a tsunami forms and moves across the ocean, the wave compresses and extends the air above, creating motions known as internal gravity waves. As the gravity waves move upwards, they are amplified in the thinning atmosphere and cause detectable changes to electron density at between 186 and 217miles. The changes can then be detected as satellites move through the disturbance.

The international team led by Sapienza’s Mattia Crespi hope to use their algorithm to monitor data from satellites near an earthquake’s epicentre, providing risk assessments and maps of where the tsunami could strike. “We expect to show it is feasible to use ionospheric measurements to detect tsunamis before they impact populated areas,” said supervisor Attila Komjathy. “This approach will add additional information to existing systems, complementing other approaches.”

Scientists currently rely on data from many sources, including seismometers, buoys and ocean pressure sensors, to detect tsunamis. The U.S. National Weather Service said there are an average of two tsunamis per year which cause damage near the source, with more destructive, ocean-wide tsunamis happening every 15 years on average.

The Varion method could help warn people living further away from the epicentre, said earthquake engineering expert Tiziana Rossetto of University College London to Professional Engineering. “It’s not going to help coastlines which are very close to tsunami sources, but it will help coastlines further away,” she said. “They don’t feel the ground shaking, so they don’t have the natural warning you would have if you’re closer.”

There is a lot of uncertainty around whether the technique can be used practically in a warning system, said Rossetto, but she added that “it would be a fantastic addition to more traditional methods” if it works. “The more information that can be developed to get a real-time idea of how big the tsunami is and therefore what extent of land could be affected… then great, fantastic. If it’s possible and if it’s possible to get that information in a timely way, really quickly, then that might be fantastic.”

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