One of The Hot, Dense Blobs Deep Inside Earth Has Been Revealed With New Imaging

Scientists have looked at an ultra-low velocity zone for the first time. There are pockets of rock close to the Earth's core, which is about 1,700 miles below the surface.

We know they are there because of the way seismic waves flow through Earth. These zones are named after the way seismic waves slow down as they pass through them.

Up until this point, images of these zones have been hard to analyze, but a new study reveals a zone beneath Hawaii in much more detail, providing fresh insight into the inner workings of our planet and its history.

There is a drawing of the ultra-low velocity zone. Nature Communications, 2022.

The most fascinating and complex features of the deep interior of the Earth are those.

The first solid evidence to show their internal structure is a real milestone in deep Earth seismology.

Computational modeling techniques were used to create the image, using a high-frequency signal that was recorded as seismic waves rippled through the ultra-low velocity zone.

It gives experts a kilometer-scale look at the rock pocket, a resolution improvement in the order of magnitudes when it comes to studying the boundary between Earth's iron-nickel core and the mantle.

The flow of the hot mantle rock is what causes earthquakes, and scientists are interested in learning more about how ultra-low velocity zones might be triggering or influencing that activity.

It is thought that extra iron in these unusual zones might be creating the additional density that shows up on seismic wave patterns, and that finding out one way or the other might tell us more about how Earth formed and how its core operates today.

It's possible that this iron-rich material is a remnant of ancient rocks from Earth's early history or that iron might be leaking from the core by an unknown means.

There is a link between ultra-low velocity zones and volcanic hot spots. There is a possibility that the material shooting up from the core could be the cause of the hotspots.

Scientists are studying basalt rock in Hawaii to look for evidence of core leaking, and better imagery of these deep and mysterious zones should help in that field as well.

The study of ultra-low velocity zones is limited in some respects by where earthquakes occur and where seismographs are installed, but the team is keen to apply their high resolution imagery enhancements to other deep pockets of Earth.

We are pushing the limits of modern high- performance computing for elastodynamic simulations, taking advantage of wave symmetries unnoticed or unused before, says data scientist Kuangdai Leng from the University of Oxford in the UK.

The research has been published.