At the center of Earth is a solid metal ball, a kind of “planet within a planet,” whose existence makes life on the surface possible, at least as we know it.
How Earth’s inner core formed, grew and evolved over time remains a mystery, one that a team of University of Utah-led researchers is seeking to plumb with the help of seismic waves from naturally occurring earthquakes. While this 2,442-kilometer-diameter sphere comprises less than 1% of Earth’s total volume, its existence is responsible for the planet’s magnetic field, without which the planet would be a much different place.
But the inner core is not the homogenous mass that was once assumed by scientists, but rather it’s more like a tapestry of different “fabrics,” according to Guanning Pang, a former doctoral student in the U’s Department of Geology & Geophysics.
“For the first time we confirmed that this kind of inhomogeneity is everywhere inside the inner core,” Pang said. Now a post-doctoral researcher at Cornell University, Pang is the lead author of a new study, published July 5 in the journal Nature that opens a window into the deepest reaches of Earth. He conducted the study as part of his doctoral dissertation at Utah.
The other final frontier
“What our study was about was trying to look inside the inner core,” said U seismologist Keith Koper, who oversaw the study. “It’s like a frontier area. Anytime you want to image the interior of something, you have to strip away the shallow effects. So this is the hardest place to make images, the deepest part, and there are still things that are unknown about it.”
This research harnessed a special dataset generated by a global network of seismic arrays set up to detect nuclear blasts. In 1996, the United Nations established the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization, CTBTO, to ensure compliance with the international treaty that bans such explosions.
Read the entire story by Brian Maffly in @theU.