All posts tagged: Earth core

Antarctic seismic data points to an ancient structure circling Earth’s core

Antarctic seismic data points to an ancient structure circling Earth’s core

Published by Jenni Sidey

A layer only a few to a few dozen kilometers thick may be draped across the boundary between Earth’s core and mantle, and researchers say it likely consists of ancient ocean floor pushed deep underground over geologic time. That is the picture emerging from a study led by The University of Alabama, published in Science Advances, which used seismic data from Antarctica to probe a vast stretch of the Southern Hemisphere nearly 2,000 miles below the surface. The team found evidence that ultralow velocity zones, or ULVZs, are not just isolated patches in a few places. Instead, they may be widespread along the core-mantle boundary. These zones slow seismic waves and appear denser than the surrounding deep mantle. The researchers argue that the best explanation is old oceanic material that sank through subduction, then spread and accumulated along the bottom of the mantle. “Seismic investigations, such as ours, provide the highest resolution imaging of the interior structure of our planet, and we are finding that this structure is vastly more complicated than once thought,” said …

Earth’s magnetic poles once took 70,000 years to reverse

Earth’s magnetic poles once took 70,000 years to reverse

Published by Jenni Sidey

Earth’s magnetic field does not simply switch direction like a flipped light switch. It weakens, wanders, and reorganizes itself over thousands of years before settling again. For decades, researchers believed most of these geomagnetic reversals followed a fairly consistent timeline, usually wrapping up within about 10,000 years. Evidence from sediments buried deep beneath the North Atlantic now suggests that assumption may be too simple. A newly analyzed record indicates that one ancient magnetic reversal stretched for roughly 70,000 years, far longer than scientists had previously documented. The findings point to a magnetic system that behaves with more variability and complexity than once thought, with possible consequences for Earth’s atmosphere and life during those unstable periods. The Northern Lights (aurora borealis) are created when charged particles from the Sun’s solar wind/coronal mass ejections interact with Earth’s magnetic field. (CREDIT: Shutterstock) Sediments that captured a rare moment The discovery traces back to a 2012 drilling expedition off Newfoundland, part of the Integrated Ocean Drilling Program’s Expedition 342. Scientists extracted sediment cores from as deep as 300 meters …