By listening to the echoes of earthquakes bouncing around our planet, we can get a good idea of ​​what’s inside the Earth without cutting it off. Unfortunately, seismic waves often have inconsistencies that scientists don’t yet fully understand. One source of variability occurs in pockets of low-density material about 3,000 kilometers (just below 1,900 miles) below the surface, between the liquid iron alloy outer core and the mantle.

A new study suggests that the silicon-rich “belly” rising from the outer core may help explain some of the anomalies in the observations. Because silicon will make the particles lighter than the surrounding liquid iron, the material can escape into the mantle and settle in drifts that cause unpredictable distortions in sound waves.

“This type of silicon-rich snow can form if silicon and hydrogen are the two main light elements in the outermost core and there is a corresponding surplus,” says geologist Suyu Fu of the University of Tokyo in Japan.

To test this, the team recreated conditions inside Earth’s outer core in the lab. The iron-silicon alloy was charged into hydrogen-argon gas before ultracompression in the diamond anvil cell. These devices are often used by geologists to achieve compression levels comparable to those found on planets like ours. The samples are clamped between two diamonds (hence the name) by mechanical force and inspected for changes.

In this case, the sample was heated using lasers and tracked using X-rays. The scientists succeeded in overcoming the problem in previous experiments, in which high temperatures caused hydrogen containing iron alloy to diffuse into diamond.

“Our team developed a new method in which hydrogen is mixed with argon in diamond anvil cells,” says geoscientist Sang-Hen Dan Shim of Arizona State University.

“Argon does not react with the sample, but suppresses the diffusion of hydrogen into the diamond anvils, which allows us to achieve extreme conditions in the laboratory.”

The researchers found that under conditions of pressure and temperature similar to those in Earth’s outer core, silicon-rich “snow” crystallites can form and rise through the denser liquid iron, accumulating at the boundary between the mantle and outer core, possibly causing some. anomalies that scientists have seen under time to scan the deepest parts of the planet. You might think that none of this matters much to us on Earth’s surface, but the movement of the outer core drives our planet’s magnetic field, which in turn protects us from the ravages of space and solar air.

A better understanding of what is in the outer core, how it moves, and how this may affect its interaction with the mantle is crucial to predicting how Earth’s magnetic field may continue to function in the future.

“The crystallization of the silicon-rich alloy was discovered during our experiments on snowy winter days in Chicago during the epidemic,” says Shim. “Interestingly, this crystallization behavior can lead to the growth of silicon-rich snow in the outer core.”