NASA's GUARDIAN system: Detecting tsunamis via atmospheric rumbles

How GUARDIAN works: Tapping into atmospheric signals

During a tsunami, large areas of the ocean surface experience synchronous rises and falls, displacing a considerable amount of air above them. This displaced air generates low-frequency sound and gravity waves that propagate in all directions. Within minutes, these vibrations reach the uppermost layer of the atmosphere, known as the ionosphere. The collision of these pressure waves and charged particles in the ionosphere causes slight distortions in the signals emitted by nearby navigational satellites.

While conventional navigation systems typically correct these ionospheric disturbances, the GUARDIAN system repurposes them as valuable data for identifying natural hazards. Léo Martire, a JPL scientist developing GUARDIAN, stated, “Instead of correcting for this as an error, we use it as data to find natural hazards.” By analyzing the subtle alterations in the satellite signals, scientists can detect the onset of tsunamis and initiate timely warnings.

The potential of GUARDIAN: Rapid detection and early warning systems

The GUARDIAN system represents one of the fastest and quickest monitoring tools. Within just ten minutes, it generates a snapshot of the tsunami's rumble that reaches the ionosphere. GUARDIAN can provide up to an hour of advance warning depending on the distance between the tsunami origin and the shore.

The system's near-real-time output currently requires expert interpretation to identify signs of tsunamis. However, the technology is rapidly maturing. “We envision GUARDIAN one day complementing existing ground- and ocean-based instruments such as seismometers, buoys, and tide gauges, which are highly effective but lack systematic coverage of the open ocean,” says Siddharth Krishnamoorthy, part of the JPL development team. 

The GUARDIAN team is primarily focused on monitoring the Ring of Fire, a geologically active Pacific Ocean region where a significant percentage of tsunamis occur. Their efforts involve the development of a website that allows experts to explore near real-time ionosphere data from individual satellite stations, enabling the rapid identification of atmospheric signals related to potential tsunamis or other hazards. By expanding the coverage of GUARDIAN and refining its automated detection capabilities, the system could become an integral part of early warning strategies for coastal areas prone to tsunamis, volcanic eruptions, and earthquakes.