Scientists have more accurately constrained the composition of the Earth’s core by performing sound-velocity measurements at double the pressure of previous ones.
Building on a program started 15 years ago by Alfred Q. R. Baron in the RIKEN Materials Dynamics Laboratory, researchers have finally been able to measure the sound velocity of pure iron at static pressures corresponding to those of the Earth’s inner core. This was made possible at RIKEN
The work is interesting because it allows constraints to be placed on the composition of the Earth’s core. “We actually have amazingly little information about the center of the planet we live on,” says Baron. “Other work tracking the progress of seismological waves from earthquakes through the planet give us a model for the density and sound velocity as a function of depth—but that’s about it: the detailed composition remains unknown and the subject of debate, as the composition is important both to understand the present structure of the planet and also the evolution of the planet and even the Solar System.”
The most recent measurement, published in
Using the new results they propose a model where, in addition to iron and nickel, the Earth’s core has small amounts of silicon and sulfur.
“Further, and perhaps most important, the method can be extended to other materials allowing a new level of precision for measurements of sound velocities of materials at extreme pressures,” says Baron.
Reference: “Sound velocity of hexagonal close-packed iron to the Earth’s inner core pressure” by Daijo Ikuta, Eiji Ohtani, Hiroshi Fukui, Takeshi Sakai, Daisuke Ishikawa and Alfred Q. R. Baron, 25 November 2022, Nature Communications.
DOI: 10.1038/s41467-022-34789-2