GPS signals are used by new hazard-monitoring technology to go wave-hunting in the Pacific Ring of Fire. The long-term goal of GUARDIAN is to supplement early warning systems.
Tsunamis, which are caused by earthquakes, undersea volcanoes, and other Earth-shaking forces, can devastate coastal communities.
Every second counts when it comes to providing advance warning. NASA's Jet Propulsion Laboratory is testing a novel method for detecting the ocean's deadliest waves from the far reaches of the atmosphere.
The Science Behind It
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The air we breathe is made of different layers. The highest one is called the ionosphere. It is where the Sun's rays hit the air and make it electrically charged.
It is also where satellites send radio signals to Earth, as per NASA.
When a tsunami happens, the ocean surface goes up and down a lot, and this pushes and pulls the air above it, creating sound and gravity waves.
These waves travel up to the ionosphere, messing with its electric field and density
This affects the radio signals from the satellites. They get slightly bent or delayed as they pass through the ionosphere.
Normally, this is a bad thing for navigation. But for tsunami detection, it is a good thing.
The system that NASA uses to do this is called GUARDIAN (GNSS Upper Atmospheric Real-time Disaster Information and Alert Network).
It collects data from different types of satellites (GPS, GLONASS, Galileo) and analyzes it using a super accurate network called GDGPS (Global Differential GPS).
GUARDIAN can tell if there is a tsunami somewhere on Earth by looking for changes in the satellite signals.
It can also figure out where it is, how fast it is moving, and where it is heading.
For example, in 2011, a massive earthquake off the coast of Japan triggered a devastating tsunami that killed thousands of people and damaged nuclear power plants.
GUARDIAN was able to detect the tsunami within 15 minutes of its occurrence and track its location, speed, and direction across the Pacific Ocean.
GUARDIAN is one of the quickest ways to spot tsunamis. It can do it within 15 minutes of them happening. That's faster than other methods that use seismometers, buoys, tide gauges, and radars, as per Phys.org.
These other methods have some problems too. They can be expensive, hard to maintain, have blind spots, or give false alarms.
For example, seismometers can measure earthquakes but not all earthquakes cause tsunamis.
Buoys can measure waves but they are sparse and vulnerable to damage. Tide gauges can measure water level changes but they are only near the coast and may not have enough time to warn people.
Radars can measure wave height but they have limited range and resolution.
GUARDIAN can also help with disaster response and recovery. It can estimate how much damage and flooding a tsunami has caused.
For example, in 2004, a huge earthquake off the coast of Indonesia triggered a powerful tsunami that killed over 200,000 people in 14 countries.
GUARDIAN was able to estimate the extent of damage and flooding caused by the tsunami in different regions.
The system is still being improved and tested. The NASA folks are working with other countries to make it better and more accurate.
They hope that someday GUARDIAN will be part of the official early warning systems around the world.
Léo Martire, one of the NASA scientists who work on GUARDIAN, said: "We are very excited about this new technology and its potential to save lives and protect communities from tsunamis."
