See NASA’s GUARDIAN Catch a Tsunami

A new data visualization illustrates how an experimental NASA technology can provide extra lead time to communities in the path of a tsunami. Called GUARDIAN (GNSS Upper Atmospheric Real-time Disaster Information and Alert Network), the software detects slight distortions in satellite navigation signals to spot hazards on the move..

The animation breaks down a real-life case study: last summer’s massive Kamchatka earthquake and the tsunami that it sent racing across the Pacific and towards Hawaii at over 500 mph (805 kph).

The visualization shows the magnitude 8.8 earthquake (seen in purple) strike off the Russian coast on July 29, 2025, triggering the tsunami. The red, orange, yellow, and green ringlets represent real-time readings from ground stations tracking GPS and other navigational satellite signals. The disturbances were spotted by GUARDIAN’s artificial intelligence-powered detection algorithms as soon as eight minutes after the earthquake.

For the next several hours, signs of the tsunami were picked up by GUARDIAN across the Pacific Ocean in near real time. The system flagged an incoming wave off the coast of Kauai some 32 minutes before it made landfall and was detected by tide gauges (shown in blue).

The results highlight GUARDIAN’s potential to augment existing early warning systems, said Camille Martire, one of its developers at NASA’s Jet Propulsion Laboratory in Southern California.

Currently, determining whether an earthquake generated a tsunami remains a challenge. Forecasters rely on seismic data and computer simulations to make their best prediction, then wait for pressure sensors attached to the ocean floor to confirm a passing wave. Those sensors work well but are expensive and thinly dispersed. Gaps in coverage remain. And in those gaps, warning time disappears.

The GUARDIAN approach is complementary and cost effective because it monitors existing data from GPS and other constellations that make up the Global Navigation Satellite System. It’s also free to access, though for now best suited to analysts trained to interpret its findings.

How GUARDIAN works

All day, every day, geopositioning constellations transmit radio signals to ground stations around the globe. On the ground, the data is refined to sub-decimeter (less than 10 centimeters) positioning accuracy by JPL’s Global Differential GPS System. Before the signals get there, however, they must travel through an electrically charged skin of plasma called the ionosphere.

Solar storms and other space weather can wreak electrical mayhem in the ionosphere, and so can events on Earth. Tsunamis and earthquakes, by displacing large amount of air at Earth’s surface, unleash pressure waves that can slightly perturb the radio signals coming down from satellites. While systems are in place to correct for this “noise,” GUARDIAN considers it a useful signal.

Currently, GUARDIAN scours data from more than 350 GNSS ground stations around the Pacific Ring of Fire, a hotbed for the ocean’s deadliest waves. And the system is not confined to tsunamis. Earthquakes, volcanic eruptions, missile tests, spacecraft reentries, meteoroid splashdowns — anything that produces a large rumble on Earth is potentially fair game. While the Kamchatka event didn’t cause widespread damage to people or property, it showed how the next time disaster strikes, NASA science could give communities a few more minutes to act.

GUARDIAN is being developed at JPL by the GDGPS project, which is partially supported by NASA’s Space Geodesy Project.