The Mariana Trench is the deepest underwater location on Earth. Recently, it has not only revealed that it has been hiding plastic particles but many other secrets as well. A scientific study conducted in the Mariana Trench has been looking into the astonishing phenomenon that, until recently, has apparently been very underestimated by scientists.The Earth is ‘swallowing' its oceansA team of researchers from the University of Washington used a series of seismic sensors to monitor and analyse tectonic activity in the world’s deepest trench and they came to the conclusion that the Earth is, slowly but surely, ‘swallowing' its oceans.Chen Cai is the head of the study which was published in the scientific journal Nature. He explained:Before we did this study, every researcher knew that water must be carried down by the subducting slab. But they just didn’t know how much water.So in order to clear up major discrepancies in previous studies, Cai and his team started investigating. With a total of 19 seismic sensors placed at the bottom of the ocean along the Mariana Trench and seven measuring devices distributed across the islands, the researchers recorded the sounds made by the Earth, from simple background noises to the rumble of earthquakes. The spot they were investigating in the Mariana Trench is where the Pacific plate pushes underneath the Philippine plate and towards the Earth’s mantle.From waterfalls to volcanoesThe movements made by tectonic plates transport considerable amounts of water from the surface of the Earth where it becomes incorporated into the rocks that lie below the surface. This sediment, and consequently the water as well, are drawn deeper and deeper into the Earth’s mantle by subduction. When volcanic eruptions occur, it reappears in the form of water vapour.But this study also raises a few questions. Such high quantities of water cannot be released through just volcanic eruptions. In fact, the Earth actually swallows up four times more water than we previously assumed in the Mariana Trench alone. According to their calculations, around three times as much water disappears below the Earth’s crust than we previously believed. Candace Major, a program director in the National Science Foundation’s Division of Ocean Sciences, stated:The research shows that subduction zones move far more water into Earth's deep interior - many miles below the surface - than previously thought. The results highlight the important role of subduction zones in the Earth’s water cycle.Exciting revelations from the depths of the ocean!