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Geophysicists have discovered mysterious zones under the Pacific Ocean floor in which “sunken” rocks are located in places that do not correspond to modern theories of plate tectonics, which could significantly change the idea of the structure of the Earth's mantle.
The study, conducted by scientists from ETH Zurich and the California Institute of Technology, was based on the use of high-resolution seismic tomography. A computer model built on the basis of data on the propagation of seismic waves has revealed anomalies under the western part of the Pacific Ocean. These anomalies indicate the existence of zones with a rock character similar to tectonic plates, but in regions where subduction did not occur during the geological past.
Seismic waves generated during earthquakes make it possible to study the internal structure of the Earth. Geophysicists usually record the sinking of plates in subduction zones—areas where one tectonic plate sinks beneath another. However, a new technique using full waveform inversion has expanded the analysis capabilities. According to Professor Andreas Fichtner, the "new tool" made it possible to see structures that had previously remained invisible, like the unexpected discovery of a hidden artery.
Scientists suggest that the anomalous zones may be the remains of ancient silicon-rich material that has been preserved since the formation of the Earth, or clusters of iron-bearing rocks that formed over billions of years. To build the models, the researchers used the Piz Daint supercomputer, since the new technique requires significant computing resources.
These discoveries are an important step in the study of the internal dynamics of the Earth, because they indicate a greater prevalence and complexity of geological processes in the mantle than previously assumed. Further research using alternative methods should help clarify the nature of these anomalies and their impact on the evolution of our planet.
