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NASA's Guardian Tsunami Detection Tech Catches Wave in Real Time

NASA's Guardian Tsunami Detection Tech Catches Wave in Real Time

2 comments

·September 12, 2025
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rich_sasha

This is unreal and beyond cool. Instead of measuring seismic tremors, it measures, indirectly, the displacement of the ocean surface. Far from the shore, tsunami waves are very long and very low - so they would appear as the whole surface of the ocean going up and down.

That motion pushes air upwards, resulting in a wave reaching high up through the atmosphere, eventually hitting (!) the ionosphere. I didn't even know acoustic waves would propagate through ionised gas!

Finally, this ionosphere disturbance affects GPS signal reception, and can be measured via ground receiver stations.

The upside of this is that it measures, indirectly, motion of the sea, i.e. actual tsunami activity, rather than monitoring directly the potential causes thereof.

It is crazy to me that it works though!

porridgeraisin

Is this how it's measured? Just to see if I got it right:

The atmosphere directly above the tsunami will have a different TEC (total electron count) pattern due to the upward acoustic waves created by the tsunami waves. This patch of atmosphere may or may not be in the line of sight of your many GPS receivers, to some satellite. Those for which it is in the line of sight will show a disturbance. Others won't. You can now cross-compare to "triangulate" where the tsunami waves are.