If you’ve experienced any kind of tectonic boundary – including volcanoes, mountain ranges, or fault lines like the San Andreas Fault – you’ll be aware that the plates that sit below the ground under our feet are prone to move a little every now and then.

And when they do, the landscape can change slightly.

This can result in magma forming fresh crust when a gap results from them moving apart; or, in the opposite instance, mountain ranges and volcanoes can form from the colliding plates pushing together, and one coming out on top.

Incidentally, it was plate tectonics at work over millions of years that was responsible for the continental drift that resulted in our continents being shaped as they are today, instead of the one super continental land mass that they once were.

We know all this thanks to models that use data from earthquake recordings to provide geophysicists with vital information about what happens deep within the Earth.

And the models generated from these seismic recordings have shown scientists, over time, exactly where plates have pushed under one another to form the continental system as we know it today.

However, using new software that allows this data to be interpreted in much more detail, researchers at ETH Zurich and the California Institute of Technology have found something that has astounded the geophysics community.

Alongside the previously-acknowledged submerged tectonic plates, surprising new areas that resemble these buried plates have been identified.

And it’s something that they had no clue about before.

As explained in a recent article in the journal Scientific Reports, the presence of these submerged plates is unusual since they are not located at our known plate boundaries, leaving researchers baffled as to how they got there.

But nonetheless, these submerged plates – situated underneath land or oceanic plates – are evident through the models, created by inputting the data from all known earthquake recordings at the same time.

And, as Thomas Schouten – a doctoral researcher at ETH Zurich’s Geological Institute – explained in a statement, their discovery seems to be just the tip of the iceberg, leading to some compelling theories:

“Apparently, such zones in the Earth’s mantle are much more widespread than previously thought. We think that the anomalies in the lower mantle have a variety of origins.

It could be either ancient, silica-rich material that has been there since the formation of the mantle about 4 billion years ago and has survived despite the convective movements in the mantle, or zones where iron-rich rocks accumulate as a consequence of these mantle movements over billions of years.”

Regardless of its origins, the presence of this anomalous material – including some beneath the Pacific Ocean – presents geophysicists with a lot of new questions and challenges, as ETH Zurich’s Professor Andreas Fichtner continued:

“It’s like a doctor who has been examining blood circulation with ultrasound for decades and finds arteries exactly where he expects them. Then if you give him a new, better examination tool, he suddenly sees an artery in the buttock that doesn’t really belong there. That’s exactly how we feel about the new findings.”

While the team continue to observe the anomalous areas and code the models to help understand them, the mysterious areas remain just that: a mystery.

Let’s hope that their continued work brings a conclusive answer to the question: are there lost worlds under our own?

If you thought that was interesting, you might like to read about why we should be worried about the leak in the bottom of the ocean.