REVEALED: Earth's Core Has Two Mysterious Protrusions - And They're Different!

Welcome, curious minds! At FreeAstroScience.com, we're thrilled to bring you another fascinating journey into the hidden depths of our planet. Today, we're exploring a mystery that has puzzled geologists for decades - the two massive structures sitting at Earth's core-mantle boundary. What makes these formations even more intriguing? Scientists have recently discovered they're not identical twins as previously thought! We invite you to join us as we dive nearly 3,000 kilometers beneath our feet to understand these ancient structures that might influence everything from our planet's magnetic shield to volcanic eruptions. Stay with us until the end to grasp how these hidden giants impact life on Earth's surface!

How the Earth might look if we could see through to the Large Low Velocity Province that lies under Africa and some neighboring areas.  Image Credit: Jeroen Ritsema et al

Earth's Hidden Giants: What Are LLVPs?

Deep within our planet, where the molten outer core meets the lower mantle, lie two enormous structures that scientists call Large Low-Velocity Provinces (LLVPs). These continent-sized formations got their name because seismic waves slow down when passing through them.

How We Discovered Earth's Deep Secrets

We can't simply drill down to see these structures. Instead, scientists study them by analyzing how earthquake waves travel through Earth's interior. These waves change speed and direction when they encounter different materials - like detectives following clues to map out what's hidden below.

Since the 1970s, researchers have known about these two mysterious provinces, but their true nature remained elusive. One sits beneath Africa, Spain, and parts of the Atlantic, while the other lies under the Pacific Ocean. Together, they cover more than a quarter of Earth's core surface and rise nearly 900 kilometers (559 miles) into the mantle.

Breaking News: The Twins Aren't Identical

For decades, scientists assumed these two structures had similar compositions and origins. Recent research published in Scientific Reports has overturned this assumption.

The African LLVP: The Elder Sibling

The African LLVP appears to be:

• Considerably older
• Made of better-mixed materials
• Less dense than its Pacific counterpart
• Extending higher from the core surface

The Pacific LLVP: The Younger Formation

In contrast, the Pacific LLVP contains:

• Younger oceanic crust (in geological terms, material from the last 300 million years)
• Less thoroughly mixed material
• Higher density composition
• A lower overall height from the core surface

Why Are They Different? The Plate Tectonic Connection

The difference between these two massive structures isn't random. It directly connects to what's happening on Earth's surface.

The Pacific LLVP keeps receiving "fresh" material from the Ring of Fire - the horseshoe-shaped belt of subduction zones surrounding the Pacific Ocean. Here, oceanic crust gets forced deep into the Earth when one tectonic plate slides beneath another.

Meanwhile, the African LLVP receives much less new material. The African plate moves more slowly, sending less crust downward. What does descend has more time to mix with surrounding mantle material during its journey.

Dr. James Panton of Cardiff University, who led the recent study, explains: "Each time, we find the Pacific LLVP to be enriched in subducted oceanic crust, implying that Earth's recent subduction history is driving this difference."

Why Were These Differences Hidden?

You might wonder why scientists took so long to notice these differences. The answer lies in temperature.

Both LLVPs share similar temperatures despite their different compositions. Since temperature affects seismic wave speed more than composition does, the two structures appeared similar in seismic studies.

Dr. Paula Koelemeijer of the University of Oxford clarifies: "The fact that these two LLVPs differ in composition, but not in temperature is key to the story and explains why they appear to be the same seismically."

Why Should You Care About Deep Earth Structures?

These deep formations might seem too distant to matter in our daily lives, but they influence several critical Earth systems.

Earth's Magnetic Shield

The LLVPs affect how heat escapes from Earth's core. This uneven heat flow contributes to convection currents in the outer core, which generate our planet's magnetic field. Without this invisible shield, life as we know it would be exposed to harmful solar radiation.

Supervolcano Connections

Some evidence suggests these deep structures might influence where supervolcanoes form. By understanding the LLVPs better, scientists might improve their ability to predict future volcanic activity.

Rewriting Earth's History

These findings contradict previous theories that LLVPs formed during the massive collision that created the Moon. Instead, they reflect ongoing processes related to plate tectonics, offering new insights into Earth's evolution.

What This Means For Earth Science

This discovery represents a significant step forward in understanding our planet's inner workings. By recognizing that Earth's deep interior is more complex and dynamic than previously thought, scientists can develop better models of:

• Earth's thermal evolution
• The history of plate tectonics
• Future changes in the geomagnetic field
• Patterns of deep mantle circulation

The research also highlights the fascinating connection between surface processes we can observe and deep structures hidden far below our feet.

Conclusion

As we've explored together, Earth's mysterious core protrusions are a testament to our planet's dynamic nature. These ancient structures, with their different compositions and origins, remind us that Earth is constantly evolving - from its surface down to its deepest layers. At FreeAstroScience.com, we believe that understanding these hidden processes helps us appreciate the complex system that supports life on our planet. These findings open new questions about Earth's past and future, inviting us to look beneath the surface and wonder about the unseen forces shaping our world. What other secrets might Earth's deep interior hold, and how might they influence the planet we call home? The journey of discovery continues, and we're excited to explore it with you.