The interior of the Earth is cooling faster than expected, a study has found — meaning our planet will become inactive like Mercury and Mars sooner than thought.
ETH Zürich-led researchers studied the thermal properties of bridgmanite, the primary mineral that makes up the boundary between Earth’s mantle and outer core.
It determines how much heat can flow from the hot iron-nickel core into the cooler and viscous mantle.
Using a laser on a diamond anvil press to simulate core–mantle boundary conditions, the team found that bridgmanite conducts heat 1.5 times better than thought.
This will likely mean that plate tectonics — which is dependent on heat-driven convection in the mantle — will slow down faster than previously thought.
The exact timescale of this entire process is unknown.
The interior of the Earth (depicted) is cooling faster than expected, a study has concluded — meaning our planet will become inactive like Mercury and Mars sooner than thought
The investigation was undertaken by earth scientist Motohiko Murakami of ETH Zürich and his international team of colleagues.
Professor Murakami explained that “our results may give us a different perspective on Earth’s evolution’s dynamics.”
“They suggested that Earth is becoming less active than anticipated, similar to the Mercury and Mars rocky planets.
Estimating how much heat bridgmanite can transfer from the core to the mantle has long been challenging, because experimentally verifying the thermal conductivity of the mineral at such extreme conditions is extremely difficult.
In their study, the team employed a ‘optical absorption’ measuring system in which a single crystal of bridgmanite was compressed within a diamond anvil cell, heated with one laser, and then probed with another.
Professor Murakami stated, “This measurement system allowed us to show that the thermal conductivity for bridgmanite was about 1.5x higher than we assumed.”
This, by extension, means that the rate at which heat escapes from the core up into the mantle will also be higher than was previously assumed — leading to increased convection of material within the mantle and a more rapidly-cooling Earth.
Researchers found that this cooling rate may increase over time.
This is because when the core–mantle boundary cools beyond a certain point, the mineral phase that is stable at this interface will change from bridgmanite to post-perovskite, which conducts heat even more efficiently than bridgmanite.
Their study used an ‘optical Absorption’ measurement system. A single crystal of Bridgmanite was placed within a diamond-anvil cell (left), and heated using one laser. Then, another crystal was probed with the other (at the location of the red dot in right-hand image).
It is not clear, however, how long it will take convention currents in the mantle, to come to an abrupt halt.
‘We still don’t know enough about these kinds of events to pin down their timing,’ Professor Murakami said — noting that we first need a better understanding of the ways that mantle convection works both spatially and temporally.
Earth scientist also stated that it was important to understand how the Earth’s mantle dynamics would change due to the radioactive element decay in its core. The core is the source of Earth’s primary heat sources.
The journal Earth and Planetary Science Letters published the full results of the study.
Earth’s movement is under our feet. Tectonic plates are moving through the earth and producing Earthquakes.
The mantle’s uppermost layer and Earth’s crust make up the tectonic plate.
Below, you’ll find the asthenosphere. It is the warm, viscous conveyor belt made of rock upon which tectonic plates move.
Earth’s fifteen tectonic plate (pictured) have shaped the terrain we see today.
Earthquakes occur near the edges of tectonic plates. This is when one plate falls below another or thrusts another upward.
While earthquakes are not common in the middle plates of the plate, they do occur when old faults or fractures below the surface activate.
This area is relatively weak in comparison to the surrounding plates and may slip easily and cause an earthquake.