Ultra-high Pressure Experiment Reveals Earth's Core Not as Strong as Once Thought

The notion that Earth's core is a rock-solid orb of iron is being challenged by a new study that suggests the inner core might only be 40 percent as strong as once thought.

According to Stanford University researchers, who reportedly conducted the most accurate experiment to-date in simulating the immense pressures deep within the planet's interior, the iron core of the planet is surprisingly not as strong as expected.  

In a laboratory, the researchers used a diamond anvil cell to squeeze iron at pressures as high as 3 million times that felt at sea level to recreate conditions at the center of the Earth. The device can exert extreme pressure on tiny samples. Pure iron was clenched between two diamonds at pressures between 200 and 300 gigapascals (the equivalent of 2 million to 3 million Earth atmospheres). Previous experiments were only conducted at 10 gigapascals.   

"The strength of iron under these extreme pressures is startlingly weak," Arianna Gleason, a postdoctoral researcher at Stanford's Geological and Environmental Sciences department, said in a news release.

"This strength measurement can help us understand how the core deforms over long time scales, which influences how we think about Earth's evolution and planetary evolution in general."

Gleason said that the latest advancements in laboratory techniques enabled her and co-author Wendy Mao to make the measurements. "We really pushed the limit here in terms of experimental conditions," Gleason said.

The authors hope that their data will help other researchers set more realistic variables when conducting future research.

"People modeling the inner core haven't had many experimental constraints, because it's so difficult to make measurements under those conditions," Mao said. "There really weren't constraints on how strong the core was, so this is really a fundamental new constraint."

The research is published in the journal Nature Geoscience.