Miles beneath the Pacific Ocean, in a region of Earth’s mantle where conventional wisdom says nothing unusual should exist, scientists have discovered something extraordinary. Using innovative technology to analyze seismic waves, researchers have identified massive structures that challenge fundamental theories about how our planet formed and evolved. It’s as if we’ve discovered a new geological continent – not on Earth’s surface, but deep within it.
Just as doctors use ultrasound waves to peer inside the human body without surgery, geophysicists employ seismic waves from earthquakes to study Earth’s deep interior. When earthquakes occur, they send waves in all directions through the planet. These waves travel at different speeds depending on the materials they encounter, getting bent, bounced, and scattered along the way. By recording these waves at seismic stations worldwide, scientists can create images of structures deep within Earth, much like creating a medical scan of our planet.
For decades, this technique revealed fast-moving wave patterns primarily beneath areas where tectonic plates collide and one plate dives beneath another – a process called subduction. These patterns were thought to be the remains of ancient tectonic plates that had sunk into Earth’s mantle, the layer between the crust and core. However, the earth-shattering new study, published in Scientific Reports, has uncovered something unexpected.
Using one of the world’s most powerful supercomputers, the Piz Daint at CSCS in Lugano, researchers from ETH Zurich and the California Institute of Technology have discovered similar wave patterns in places where they shouldn’t exist – beneath vast oceans and continental interiors, far from any known plate boundaries. “Apparently, such zones in the Earth’s mantle are much more widespread than previously thought,” says Thomas Schouten, the study’s lead author and doctoral student at ETH Zurich’s Geological Institute, in a statement.
The key to this discovery lies in a sophisticated technique called full-waveform inversion (FWI). Unlike traditional methods that analyze only specific types of seismic waves, FWI examines entire seismograms, capturing a more complete picture of Earth’s interior. This comprehensive approach requires enormous computational power but provides unprecedented detail.
The most striking finding emerged beneath the western Pacific Ocean, where researchers identified a massive anomaly between 900 and 1,200 kilometers depth. According to current plate tectonic theories, this material couldn’t have come from subducted plates because the region has no recent history of subduction zones.
ETH professor Andreas Fichtner, who developed the computer model, draws a medical parallel: “It’s like a doctor who has been examining blood circulation with ultrasound for decades and finds arteries exactly where he expects them. Then if you give him a new, better examination tool, he suddenly sees an artery in the buttock that doesn’t really belong there. That’s exactly how we feel about the new findings.”
The discovery suggests these deep Earth structures might have diverse origins, Schouten explains. They could be ancient silica-rich material that has survived since the mantle’s formation about 4 billion years ago, despite continuous churning movements. Alternatively, they might be zones where iron-rich rocks have accumulated over billions of years due to these mantle movements.
The research team emphasizes that current models only show wave speed patterns, which alone cannot fully explain Earth’s complex interior. Future research will need to delve deeper into the material properties creating these patterns, requiring even more sophisticated models and computational power.
Source : https://studyfinds.org/massive-structures-deep-beneath-pacific-ocean-mantle/
