A new study led by University of Chicago geophysicist Sunyoung Park suggests that there may be a surprising layer of molten rock located in the Earth’s mantle.
Nationalgeographic.co.id – New studies from University of Chicago scientists suggest that there may be a surprising layer of molten rock surrounding Earth, at the very bottom of the upper mantle.
The findings were made by measuring the lagged movement recorded by GPS sensors on islands after an earthquake deep in the Pacific Ocean near Fiji. Published February 22 in the journal Naturethis research demonstrates a new method for measuring the fluidity of the Earth’s mantle.
“Even though the mantle makes up the bulk of Earth, there’s still a lot we don’t know about it,” said Sunyoung Park, a geophysicist at the University of Chicago and lead author of the study.
“We think there is much more we can learn by using these deep earthquakes as a way to investigate these questions.”
Surprisingly, we still know very little about the Earth beneath our feet. The farthest it had been excavated was about 12 kilometers before the increasing heat completely melted the drill.
So scientists have to use clues like how seismic waves travel to deduce the various layers that make up the planet, including the crust, mantle and core.
One thing that stands in the way of scientists is a precise measurement of how thick the mantle is.
The mantle is the layer beneath the earth’s crust. It was made of rock, but at the intense temperature and pressure of those depths, it actually became viscous–flowing very slowly like honey or tar.
“We want to know exactly how fast the mantle flows, because that affects the evolution of the whole Earth – it influences how much heat the planet retains for how long, and how Earth’s material is recycled over time,” explained Park. “But our current understanding is very limited and includes many assumptions.”
The earthquake in Alaska caused seismic waves to penetrate the deepest core of the earth.
Park thinks there may be a unique way to measure mantle properties by studying the effects of very deep earthquakes.
Most of the earthquakes we hear about on the news are relatively shallow, originating in the upper layers of the Earth’s crust. But occasionally, there are earthquakes that originate deep within the Earth–up to 700 km below the surface.
