The international academic journal ‘Nature’ published this week’s cover illustration showing the protoplanet ‘Theia’ colliding with the primordial Earth and causing a huge explosion.
Theia is closely related to the theory explaining the formation of the moon. About 4.5 billion years ago, Theia collided with the Earth, throwing out large and small fragments, and the fragments coalesced to form the proto-moon. However, it was difficult to find direct evidence that Theia existed.
A research team led by Paul Ashmo, professor of geology and geochemistry at the California Institute of Technology (Caltech) and led by postdoctoral researcher Chen Yuan, published the results of a study on the 1st (local time) showing that traces of Theia’s impact remain at the interface between the Earth’s outer core and mantle in the international academic journal ‘ It was published in ‘Nature’.
The research team compared the results of seismic wave analysis of an earthquake that occurred on the West African continent with the results of a computer simulation that reproduced the movement of debris that occurred when the Earth and Theia collided about 4.5 billion years ago.
As a result, it was confirmed that there is an area where the speed of seismic waves abnormally slows down around 2897km below the surface. Since the speed of seismic waves changes depending on the medium, the change in the speed of seismic waves can be used to estimate the presence of heterogeneous materials inside the geology that are different from the surrounding area. The density of the area where seismic waves slowed down was found to be approximately 2.0-3.5% higher than the surrounding area.
The research team guessed that this was some material mixed with fragments of Theia and parts of the Earth’s crust and mantle that melted due to the collision with Theia. He explained that there is a high possibility that this material is ‘Theia Mantle Material (TMM)’ that has survived throughout Earth’s history of about 4.5 billion years.
