New Scientist
Image: Francesca Sacco
Severe storm clouds have an unexpected silver lining: they may help us visualise parts of our planet’s interior that are otherwise hidden.
Much of what we know about Earth’s interior comes from studying how seismic waves created by earthquakes travel through it. These “body waves” come in two basic forms, called P-waves and S-waves.
Such waves sweep through Earth in great arcs before returning to the surface, where geologists can detect and measure them. When they meet significant boundaries in Earth’s chemical or physical structure – at the boundary between the core and mantle, for instance – they are reflected, refracted, or even stopped in their tracks.
This means that studying the distribution of P-waves and S-waves after an earthquake helps illuminate our planet’s internal structure.
There’s just one problem with the approach. The image resolution is lower in regions where earthquakes are rare, far away from the margins of tectonic plates, says Kiwamu Nishida at the University of Tokyo, Japan.
This is where severe oceanic storms can help, he says. Atmospheric pressure can drop rapidly during these events, generating oceanic waves so strong that a small fraction of their energy makes it all the way down to the sea floor and generates faint P-waves and S-waves in the rocks – as if a very weak earthquake has occurred. Read more on newscientist.com…
