'Dynamic duo' develops framework for Earth's inaccessible interior

What's Down Below -
A new model of inner Earth constructed by Arizona State University researchers pulls past information and hypotheses into a coherent story to clarify mantle motion.



The image is shown from space, centered over the Pacific Ocean, with a cut-away displaying anomalous heterogeneities in the mantle of the Earth: red and blue regions depict zones where seismic waves propagate slower or faster than average, respectively. Distant earthquakes (e.g., the red star) send seismic energy throughout the planet, which traverses anomalous structure and brings information about Earth’s internal structure to the planet’s surface. The large red region beneath the Pacific Ocean sits atop the hot molten iron core (orange ball), is best explained as chemically distinct from the rest of the mantle, and possibly plays an important role in guiding convection currents in the mantle over geologic time scales. The blue regions underlay subduction zones at Earth’s surface, where cold and dense material falls into the planet in the recycling of Earth’s surface as part of plate tectonics. Thus the fields of seismology coupled with geodynamics are providing a self-consistent framework for depicting the evolution and dynamics of Earth’s interior. Credit: AAAS/Science
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“The past maybe two or three years there have been a lot of papers in Science and Nature about the deep mantle from seismologists and mineral physicists and it’s getting really confusing because there are contradictions amongst the different papers,” says Ed Garnero, seismologist and an associate professor in Arizona State University’s School of Earth and Space Exploration.

“But we’ve discovered that there is a single framework that is compatible with all these different findings,” he adds.

Garnero partnered with geodynamicist and assistant professor Allen McNamara, also in the School of Earth and Space Exploration in ASU’s College of Liberal Arts and Sciences, to synthesize the information for their paper to be published in the May 2 issue of Science.

“Our goal was to bring the latest seismological and dynamical results together to put some constraints on the different hypotheses we have for the mantle. If you Google ‘mantle’ you’ll see 20 different versions of what people are teaching,” explains McNamara...cont'd


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