Scientists baffled by twilight zones discovered deep within Earth: 'We don't know what they are'

While humanity looks towards the sky to explore new frontiers in space, there's a lot more hidden in Earth's core that we are yet to understand. In one such discovery about Earth's mantle, researchers stumbled upon something unique that they describe as a 'mysterious zone' of the Earth, as per Journal AGU Advances. They explored Ultra Low Velocity zones termed as "ULVZ" that slow down seismic waves responsible for earthquakes, as per PHYS.ORG.

But from their findings, scientists were only able to note that there are multiple such zones between the Earth's mantle and metallic core, 1800 miles beneath the surface. Even in the previous study conducted by graduate student Jonathan Wolf and seismologist Maureen Long of Yale, the origins of ULVZs and their role in the mantle of the earth weren’t clearly explained. “A big outstanding puzzle has been whether ULVZs are stationary features or whether they interact with the convective, flowing mantle,” Long explained.

Scientists further dived deep to understand the ULVZs and made some progress, as per Live Science. Thorne recalled his curiosity for the same branching from a previous study about seismic waves and mentioned that he was trying to measure the speed of the large quakes, known as PKP waves. While researching the same and comparing results year after year, he realized that something was drastically slowing down the waves and scattering their energy. Upon further research, it was discovered that it could be the ridges and valleys or the ULVZs that were responsible for the same. Looking at the areas studied for the impact of the waves, the presence of blobs identified as ULVZs hinted at a theory.

A recent study revealed that these zones have a lot to do with seismic waves responsible for earthquakes. It was explained that the presence and positioning of the ULVZs in the Earth’s mantle slow down the seismic waves by up to 50%. This is because the zones are present in the lower portion of the mantle and near its boundaries. Geologist and geophysicist Michael Thorne described the news as “remarkable”  and went on to add, “Here's one of the most extreme features that we see anywhere inside the planet and we don't know what they are, where they're coming from, what they're made of, [or] what role they play inside the Earth.”

Thorne suggested that ULVZs could be the remnants left after the impact of a major meteorite strike on Earth in the past. As per the study on the waves, it is possible that these zones are scattered and if that’s the case, it could mean they are actively being generated today. They could be areas of volcanic rock basalt that can eventually melt due to the mantle’s subduction, resulting in the formation of pockets responsible for slowing the seismic waves, as per the study. Since more research is needed to gain further clarity about the same, Thorne remarked, "There are a lot of open questions we don't have answers to yet."