The revolutionary technology with which scientists have discovered real-time tsunami formation that could save thousands of lives

This incident showed that NASA has a system capable of detecting a tsunami long before it reaches the coast. It was simply listening to the radio signals used by global navigation satellites when communicating with ground stations.

This same method allows us to detect volcanic eruptions, missile launches, and underground nuclear weapons tests.

“We could tell in almost real time: There’s a tsunami,” says Jeffrey Anderson, a data scientist at the US National Center for Atmospheric Research, who co-developed the Guardian system.

Anderson admits that years ago, when he first heard about proposals for this technology, which he later helped develop, the idea seemed “pretty crazy.”

The idea of ​​using radio signals transmitted between ground-based receivers and satellites to detect tsunamis in near real-time has been around for decades.

Some academic articles from the 1970s initially raised the possibility of this type of system, but it did not become a reality until the 1920s with the arrival of the Guardian System.

In 2022, Anderson and a team from NASA’s Jet Propulsion Laboratory in California published a study that provided basic details of the system.

The reason navigational satellite signals are able to record tsunamis is because of the rising and falling movement of the sea.

When a tsunami begins to form in the open sea, its waves may not be very high, perhaps between 10 and 50 cm. “They are almost invisible as they travel in the open ocean,” says Yue Cynthia Wu, a marine engineering researcher at the University of Michigan who specializes in ocean wave dynamics.

However, this churning occurs on a massive scale, moving huge amounts of water at once. This movement displaces the air above, disrupting the upper atmosphere, creating ripples in the layer of charged particles that make up the ionosphere, 50 to 300 kilometers above the Earth’s surface.

These ripples change the amount of electrons in certain regions of the ionosphere.

“Ionic interactions occur, temperatures change, and equilibrium occurs,” explains Michael Hickey, professor emeritus of physics at Embry-Riddle Aeronautical University in Daytona Beach, Florida, who has studied these atmospheric waves.

Space navigation satellites use two frequencies to communicate with ground stations, so the increased number of electrons in the ionosphere can cause unusual delays in the arrival of these two signals. By measuring these delays, systems like Guardian can detect whether any anomalies are occurring in the ionosphere.

GPS engineers already knew that signals were affected in this way. They must therefore compensate for this “noise” to ensure the accuracy of navigation systems.

But it was geoscience researchers who realized that this noise could be used to detect tsunami waves.

“These are smart people who think creatively,” Anderson says.

In recent years, researchers have been able to observe the effects of tsunamis and volcanoes in ionospheric data.

Hickey and his colleagues retrospectively studied the impact of the 9.1 magnitude earthquake that struck the northeastern coast of Japan in 2011 and triggered a tsunami.

“We saw the rings,” Hickey recalls, referring to the massive outward-expanding ripples in the ionosphere above Japan that can be visualized using electron counting data.

The massive volcanic eruption in Tonga in 2022 also left a large mark on the ionosphere, which scientists later analyzed in detail.

But until this year’s Kamchatka earthquake, no large tsunami had been detected in real time using these methods.

The US National Oceanic and Atmospheric Administration’s (NOAA) DART system, which uses buoys anchored to the seafloor, issued tsunami forecasts, but the Guardian system allowed the waves to be monitored in real time.

Studying atmospheric signals raises hopes that a system like Guardian can detect tsunami waves on the high seas, before they reach high altitudes and hit the coasts.

This would allow communities to receive more accurate early warnings about what is coming and avoid false alarms.

Moreover, this technology can be applied to phenomena other than earthquakes and volcanoes. It can also help detect nuclear explosions. For example, ripples in the ionosphere helped confirm that North Korea conducted underground nuclear weapons tests in 2009.

Until now, tsunami monitoring networks have relied on seismometers, which analyze earthquakes around the world, and ocean buoys, which detect sudden changes in wave height.

However, these devices do not provide a complete or immediate picture like ionospheric data.

“Every minute counts in tsunami evacuation, so the Guardian’s early discoveries are a really important step forward for tsunami safety,” said Harold Tobin, a seismologist at the University of Washington.

Anderson adds that observing the ionosphere rather than just seismometers, for example, could make it easier to detect tsunamis caused by events such as landslides.

And soon, Guardian may not be the only tool available.

“In Europe, we are developing our own system,” says Elvira Astafieva, a senior researcher in geophysics and space sciences at the Institute of Geophysics in Paris.

She and her colleagues hope to test their European system in the coming years, which could help monitor wide areas, including the Indian Ocean, where France, for example, has territory.

Tsunami waves can also be detected using aeroluminescence, a faint emission of light in the atmosphere affected by large atmospheric disturbances, Hickey says.

The Guardian System is still far from finished. Anderson explains that future improvements will allow him to predict the behavior of waves moving through the ocean.

“This will not only lead to automatic detection, but will also enable automatic prediction of the tsunami’s path,” Anderson says.

Roughly every 10 minutes, as the tsunami grows, such a system could automatically generate predictions about the final size of the waves, where they will hit the coast and when.

There are still some limitations. Diego Melgar, an expert on earthquakes, tsunamis and early warning systems at the University of Oregon, says it takes minutes to tens of minutes for the ionosphere to respond to a tsunami.

For communities close to the epicenter, atmospheric monitoring is very slow.

“For local warnings, the delay results in ionospheric signals arriving too late to be useful.”

However, large tsunamis can travel across entire ocean basins.

After the December 26, 2004 tsunami, which devastated the coast of the Indian Ocean and left nearly 228,000 dead, it took up to two hours for waves to reach Sri Lanka from the epicenter off the coast of Indonesia. It took seven hours for the waves to hit the eastern coast of Somalia.

Systems like Guardian can provide crucial early warnings to these remote communities in cases of similar waves.

“If something spreads a reasonable distance, yes, that will save lives,” Hickey says.

You can see here The original note is in English with links to the scientific studies mentioned.

Subscribe here Join our new newsletter to receive a selection of our best content of the week every Friday.

And remember, you can receive notifications in our app. Download the latest version and activate it.