Scientists Detect Previously Unknown Structures Beneath Pacific Ocean Basin Near Earth's Core

Rodiano Bonacci
Giugno 14, 2020

We still don't know what these blobs are - they could be magma, molten iron leaking from the core, or something else - but with a more complete, detailed map of where they are, we can better understand the geological processes occurring deep inside Earth's interior. The goal of this is to identify the echoes from the boundary situated in between the Earth's molten core and the solid mantle that lies right above it.

Scientists have focused on echoes of seismic waves traveling underneath the Pacific Ocean basin. Echoes from nearby structures arrive more quickly, while those from larger structures are louder. One of the newfound large structures is located far below the Marquesas Islands from the Pacific Ocean, while the other one is far beneath the Hawaiian Islands.

A new technique of analyzing quake data has shown that there is much more of the continent-sized zones located at the boundary between the mantle and the core of our planet.

A research team recently used a novel algorithm called the Sequencer that was initially developed to find interesting trends in astronomical datasets and revealed structures deep inside the Earth, paving the way towards a new map showing what Earth's interior looks like.

Brice Ménard, an astrophysicist at Johns Hopkins University and one of the team members, said, "With this new way to look at the data globally, we were able to see weak signals much more clearly".

As the researchers explain, they were able to use seismic wave recordings to provide a kind of three-dimensional map of areas near Earth's core that revealed a surprise.

They enlisted the help of an artificial intelligence algorithm called Sequencer to make sense of thousands of seismograms captured during hundreds of major earthquakes between 1990 and 2018.

John Hopkins University, the Tel Aviv University of Israel, and the University of Maryland's (UMD) worldwide team, suggested that the previously discovered ULVZ is much larger compared to the previous data as new evidence suggests. These are called shear waves, and these were similar across multiple earthquakes, which distinguished them from random noise. The examination distributed in the diary Science gives an exhaustive perspective on the center mantle limit underneath the Pacific Ocean, making it the first to cover such a wide region indefinite goals.

"We found echoes on about 40 percent of all seismic wave paths", Lekić said. Known as ultralow-velocity zones (ULVZs), such patches are found at the roots of volcanic plumes, where hot rock rises from the core-mantle boundary region to produce volcanic islands.

"This is really exciting, because it shows how the Sequencer algorithm can help us to contextualise seismogram data across the globe in a way we couldn't before".

"That was surprising because we were expecting them to be rarer, and what that means is the anomalous structures at the core-mantle boundary are much more widespread than previously thought", he said.

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