A groundbreaking discovery published in Nature has revealed the existence of Earth’s largest mountains, located deep beneath the surface on the boundary between Africa and the Pacific Ocean. These newly identified mountains are more than 100 times taller than Mount Everest, with heights reaching approximately 1,000 km, far surpassing the 8.8 km peak of Everest. The research suggests that these peaks are ancient, estimated to be at least 500 million years old, though they could date back as far as the formation of Earth itself, over four billion years ago.
Mysterious Structures Beneath Earth’s Surface
These massive mountains reside on the boundary between Earth’s core and mantle, the semi-solid layer beneath the Earth’s crust. They sit in a region known for a massive “graveyard of tectonic plates,” a product of a process called subduction, where one tectonic plate dives beneath another and sinks deep into the Earth’s interior. Researchers, led by Dr. Arwen Deuss, a seismologist from Utrecht University, remain uncertain about the true nature of these colossal formations, speculating whether they are temporary phenomena or have been present for millions, if not billions, of years.
Dr. Deuss explains, “Nobody knows what they are, and whether they are only a temporary phenomenon, or if they have been sitting there for millions or perhaps even billions of years.”
Seismic Waves Reveal Hidden Peaks
Scientists have long known that massive structures exist deep within the Earth’s mantle, discovered through the analysis of seismic waves caused by large earthquakes. When these waves ripple through the Earth’s interior, they reveal “out-of-tune” patterns when they encounter unusual objects, such as supercontinents or large geological anomalies. These anomalies slow down the seismic waves, creating a distinct sound that helps scientists map the structures beneath the Earth’s surface.
The researchers identified the massive underground mountains by studying how seismic waves behave as they pass through the Earth’s mantle. “We see that seismic waves slow down there,” said Dr. Deuss, referring to the discovery of the formations, now known as Large Low Seismic Velocity Provinces (LLSVPs).
Hotter Than Surrounding Tectonic Plates
The newly discovered mountains are hotter than the surrounding tectonic plates, adding another layer of mystery to their formation. Researchers were initially puzzled by the seismic wave behavior, which showed minimal damping in the LLSVPs, making the seismic “tones” sound unusually loud. In contrast, the cold tectonic slab graveyard showed much more damping, with the seismic waves sounding softer.
Sujania Talavera-Soza, a colleague of Dr. Deuss, explained, “Against our expectations, we found little damping in the LLSVPs, which made the tones sound very loud there. But we did find a lot of damping in the cold slab graveyard, where the tones sounded very soft.” She likened this phenomenon to running in hot weather, where you not only slow down but become more fatigued compared to running in cooler conditions.
Understanding the Age of the Mountains
The study suggests that the mountains are composed of larger mineral grains than the surrounding slabs. These grains are believed to have grown over billions of years, making the LLSVPs much older than the surrounding geological features.
“Those mineral grains do not grow overnight, which can only mean one thing: LLSVPs are lots and lots older than the surrounding slab graveyards,” said Talavera-Soza, highlighting the ancient nature of these massive structures.
A New Frontier in Earth’s Deep Interior
The discovery of these enormous underground mountains opens new avenues for studying the Earth’s deep interior. The findings challenge previous assumptions about the Earth’s mantle and its geological processes, offering new insights into the planet’s formation and evolution.
As researchers continue to unravel the mysteries of these colossal structures, the study provides a glimpse into a hidden world beneath our feet, far beyond the reach of traditional exploration.