Remains of submerged plates discovered under the Pacific

Madrid. With the help of a new high-resolution model, a team of geophysicists discovered new areas inside the Earth that look like the remains of submerged plates.

One is located under the western Pacific. However, according to current theories and knowledge of plate tectonics, there should be no subducted plate material there, because it is impossible for there to have been subduction zones nearby in recent geological history. Researchers don’t know for sure what material it is instead and what that would mean for the Earth’s internal dynamics.

That is our dilemma. With the new high-resolution model we can see these types of anomalies everywhere in the Earth’s mantle, but we do not know exactly what they are or what material creates the patterns we have discovered.explained in a statement the professor at the Federal Polytechnic School (ETH) in Zurich Andreas Fichtner, author of the study. “It’s as if a doctor has been examining blood circulation with ultrasound for decades and finds arteries exactly where he expects them.

If we give him a new, better scanning instrument, he suddenly sees an artery in the buttock that really shouldn’t be there. This is exactly how we feel about the new findingsexplained the wave physicist, who developed the model in his group and wrote the code.

Silica-rich material

So far, researchers can only speculate. We believe that anomalies in the lower mantle have a variety of originssaid Thomas Schouten, first author and PhD student at the ETH Geological Institute.

He believes it may not simply be cold plate material that has been subducted over the past 200 million years, as previously assumed. “It could be ancient silica-rich material that has been there since the formation of the mantle about 4 billion years ago and has survived despite convective movements in the mantle, or areas where iron-rich rocks accumulate such as consequence of these movements of the mantle for billions of years,” he noted.

For the doctoral student, this means above all that more research with even better models is needed to see more details of the Earth’s interior. The waves we use for the model essentially only represent one property, namely the speed at which they travel through the Earth’s interior.said the geoscientist. However, this does not do justice to the complex interior of the Earth. We have to calculate the different material parameters that could generate the observed speeds of the different types of waves. Basically, we have to delve into the material properties behind wave speed.

seismic wave

The study was published in the journal Scientific Reports by a team of geophysicists from ETH Zurich and the California Institute of Technology.

These scientists not only used one type of seismic wave to study the structure of the Earth’s interior, but all of them.

Experts call this procedure full waveform inversion. This makes the model very computationally intensive, so the researchers used the Piz Daint supercomputer at the CSCS in Lugano.