Core on EARTH Magazine

Are diatoms triggering submarine landslides?

Tue, 01 May 2018 16:19:16 -0400

A scanning electron microscope image of marine diatom mud. Credit: Gauvain Wiemer/MARUM/University of Bremen.

Far beneath the ocean’s surface, puzzling deposits from huge submarine landslides can be found amid expanses of nearly flat ocean floor. Without steep terrain, what causes these megaslides? In a new study, scientists who delved into deep-sea drilling records report a potential trigger for one such slide off the coast of northwest Africa: diatom ooze.

Glass shards reveal a fiery history in Ethiopia

Thu, 14 Sep 2017 11:51:18 -0400

Scientists drilled below Lake Ashenge, on the western border of the Afar Triangle, for evidence of past eruptions. Credit: Catherine Martin-Jones.

Chains of volcanoes and a lava lake pepper the landscape of the Afar Triangle in northeastern Ethiopia, where eruptions and earthquakes are byproducts of the rifting that is literally ripping Africa apart, but recent eruptions have been docile. Now, scientists studying ash deposits from the last 40,000 years are showing that dangerous, explosive eruptions present an ongoing hazard, striking the region every 1,000 years on average.

Magnesium part of Earth's magnetic field engine

Tue, 19 Apr 2016 15:47:36 -0400

An artist's interpretation of how the precipitation of buoyant magnesium-bearing minerals, which rise toward the core-mantle boundary, from the otherwise iron-rich core could drive compositional convection and help drive Earth's geodynamo. Credit: reprinted from Nature with permission.

Earth’s magnetic field, which arises from convective flows in the planet’s core, known as the geodynamo, has existed for at least 3.4 billion years, meaning that the field-generating processes must have existed for that long as well. But what exactly those processes have looked like throughout Earth’s history, particularly early on, has been poorly understood. In a new study, researchers suggest that magnesium mineral formation in the core is a previously unrecognized but important piece of the puzzle.

Introducing Earth's inner inner core

Tue, 16 Jun 2015 11:50:11 -0400

A humongous hunk of iron — that’s how scientists have long thought of Earth’s solid inner core. But new research suggests there’s more to it than that: namely, that the inner part of the inner core may have different physical properties than the outer part. In addition to revealing a new feature in Earth’s layer-cake internal structure, the discovery may shed light on the planet’s formation, say the authors of the study, published in Nature Geoscience.

March 29, 1936: Notes on Earth's Inner Core

Fri, 30 Jan 2015 13:35:48 -0500

Inge Lehmann worked for the Royal Danish Geodetic Institute from 1925 to 1952, heading the seismology department from 1928 until her retirement. Credit: The Royal Library, National Library of Denmark and University of Copenhagen University Library.

On March 29, 1936, Danish seismologist Inge Lehmann wrote a letter to a colleague in which she argued that seismic waves — specifically P-waves — recorded from distant earthquakes showed some anomalous characteristics. “If you had seen so many records from these distances as I have,” she wrote, “I am sure you would not doubt that the amplitudes are abnormally small.” Within the year, Lehmann published a study based on those unusual amplitudes, work that first proposed that Earth has a solid inner core inside its liquid outer core.

Ancient meteorites reveal early magnetic fields

Thu, 05 Jan 2012 06:41:58 -0500

New research suggests that some of the small rocky bodies that smashed together to form planets, called planetesimals, had magnetic fields. Damir Gamulin, courtesy of Benjamin Weiss

Even before the birth of the planets, our solar system was hardly a lonely place. Small rocky bodies, called planetesimals, filled the inner solar system, eventually colliding together to form the planets. Now a new look at a group of ancient meteorites shows that at least some planetesimals generated their own magnetic fields — a feat many scientists thought extremely difficult for such small astronomical bodies. The work also has scientists rethinking how planets formed.

Of molten iron and magnetism

Thu, 05 Jan 2012 06:41:58 -0500

Small changes in the movement of the molten iron in Earth's outer core cause parts of the magnetic field (blue lines) to fluctuate. The field protects the planet from solar flares. NASA

Since 1999, the German satellite CHAMP (CHAllenging Mini-satellite Payload) has swirled around Earth, keeping watch as the planet’s magnetic field waxes and wanes over time. CHAMP’s continuous measurements of Earth’s field have created a finely detailed picture of how the field changes both in space and in time — and by extension, how the movement of the molten iron in Earth’s outer core ebbs and flows. And thanks to these data, researchers report, they can now track even small-scale, rapid fluctuations in the field’s strength around the planet.