Scientists Discover Rocks Flowing In The Special Zone — 1700 Miles Inside The Earth's Surface
The insides of Earth remain as much of a mystery to experts as the outsides of the planet. Recently, a team of experts took a significant step towards solving the underground conundrum, according to Science Alert. Researchers seemingly have figured out what exactly happens 1,700 miles (around 2,700 kilometers), also labeled as the D" layer by experts, below the Earth's surface, which has been eluding them for decades. Findings regarding this discovery have been published in the journal Communication Earth & Environment.
Recent analysis showcased that solid rock is flowing in this zone. Past examinations have revealed that seismic waves get accelerated when they pass through the boundary of this specific layer. Researchers have deemed the rock current neither to be liquid, like molten magma, nor as solid as the brittle rock, according to the Daily Mail. Scientists have long speculated that rocks present in the depths of the planet are moved through convection currents. Further examinations conducted as part of this study confirm this theory for the first time. Professor Motohiko Murakami, lead author and geoscientist at ETH Zurich in Switzerland, claims that the confirmed theory indicates that Earth showcases activity not only on the surface but also underneath it.
The analysis took into consideration a past investigation by Murakami on the mysterious D" layer. It indicated the seismic waves possibly sped up due to interactions with a different kind of material. He concluded that perovskite, a material that makes up most of the Earth's lower mantle, changes into a new mineral around the D" layer. The geoscientists named this changed mineral post-perovskite. He speculated that the changed nature of perovskite accounted for the acceleration of seismic waves.
Further examination clarified that earthquake waves could not accelerate to the extent they are assumed to do just because of the transformation. Researchers associated with the study landed on the theory of rock current when they observed that the hardness displayed by post-perovskite was dependent on the alignment of its crystals. This discovery further helped the team to figure out that post-perovskite was extremely hard, just in one specific crystallographic direction. Seismic waves are known to increase their speed when going through harder material. This provided the link that was missing in the previous study. Along with the transformation of perovskite, its hard surfaces caused the seismic waves to accelerate. The team speculated that the hard region fell in the D" layer.
To understand the crystal alignment that facilitates this hardness, the team created a model, recreating the conditions of the D" layer. Experts took tiny grains of perovskite and crushed them at a pressure of 115 gigapascals. It implied that every square inch was experiencing a pressure of over 16 million pounds, which mimicked the conditions in the D'' layer. Researchers subjected the arrangement to extreme heat and pressure and showed that the crystals in post-perovskite all lined up in a specific direction. This implied to the geoscientists that some phenomenon was in play that was causing these crystals to arrange themselves in the same direction.
The study claims that the only phenomenon that could produce this alignment is the horizontal movement of solid rock along the boundary present between the Earth's mantle and the core. The steady motion of rocks forces the crystals to point in the same direction. This showcases that the D'' layer is essentially an undercurrent of super hard rocks. Researchers still don't have direct observations, but the findings allow them to work towards mapping the solid rock current functioning deep within the surface. This mapping could one day help them in figuring out the invisible source that drives events like volcanoes and earthquakes.