Two Titanic Buildings Hidden Deep in the Earth Have Changed the Magnetic Field for Millions of Years
This group geologists have found evidence for the first time that two ancient, continent-sized, superheated structures hidden beneath the Earth’s surface have shaped the planet’s magnetic field for the past 265 million years.
These two masses, known as large low-shear-velocity states (LLSVPs), are part of a catalog of the world’s largest and most mysterious objects. Current estimates calculate that each is comparable in size to the continent of Africa, although it remains buried at a depth of 2,900 kilometers.
Low-lying surface vertical velocity (LLVV) regions form irregular regions of the Earth’s mantle, not defined blocks of rock or metal as one might think. Inside them, the mantle material is hot, dense, and chemically different from the surrounding material. They are also notable because they have a “ring” of cooler material around them, where seismic waves travel faster.
Geologists had suspected these conflicts since the late 1970s and were able to confirm them two decades later. After another 10 years of research, they are now directly identifying themselves as structures capable of altering the Earth’s magnetic field.
LLSVPs Change the Behavior of the Nucleus
According to a study published this week in Nature Geoscience and led by researchers at the University of Liverpool, the temperature difference between the LLSVP and the surrounding material in the mantle changes the way liquid iron flows in the core. This movement of iron is responsible for generating the Earth’s magnetic field.
Combined, the cold and hot areas of the mantle speed up or slow down the flow of liquid metal depending on the location, creating an asymmetry. This imbalance contributes to the magnetism taking on the unusual shape we see today.
The team analyzed the available evidence and ran simulations on supercomputers. They compared what the magnetic field would look like if the hat were similar to how it behaves when it combines these different properties. They then compared both conditions with actual magnetic data. Only the model including LLSVPs reproduced the same anomalies, oscillations, and patterns currently observed.
Geodynamo simulations also revealed that some parts of the magnetic field have remained stable for hundreds of millions of years, while others have changed dramatically.
“These findings also have important implications for questions about ancient continental configuration—such as the formation and breakup of Pangaea—and may help resolve long-standing uncertainties about ancient climate, paleobiology, and natural resource formation,” said Andy Biggin, first author of the study and professor of Geomagnetism at the University of Liverpool, in a press release.
“These sites assumed that the Earth’s magnetic field, when measured over time, behaves like a perfect magnet along the planet’s rotational axis.“ he added.
This story appeared on WIRED en Español and has been translated from Spanish.
