‘Earth is getting soft in the middle’

Material In The Lower Mantle Makes Sound Travel More Slowly, Thereby Suggesting It Is Softer

New York: Scientists claim to have uncovered evidence that our planet Earth is getting soft in the middle.
The researchers in the United States have carried out a study and found that material in part of the planet’s lower mantle has unusual electronic characteristics which make sound propagate more slowly, suggesting it is softer.
“What’s most important for seismology is the acoustic properties — the propagation of sound. We determined the elasticity of ferropericlase (mineral) through the pressure induced high-spin to low-spin transition.
“We did this by measuring the velocity of acoustic waves propagating in different directions in a single crystal of the material and found that over an extended pressure range (from about 395,000 to 590,000 atmospheres), the material became ‘softer’ — that is, the waves slowed down more than expected from previous work.
“Thus, at high temperature corresponding distributions will become very broad, which will result in a wide range of depth having subtly anomalous properties that perhaps extend through most of the lower mantle,” the ‘ScienceDaily' quoted lead researcher Alexander Goncharov as saying.
In fact, Goncharov and his colleagues at the Carnegie Institution’s Geophysical Laboratory analysed the composition and density of the material after watching the velocity of seismic waves as they travel through Earth. PTI
Is our scarred planet entering a new epoch?
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“With more than half of all soils on Earth now being cultivated for food crops, grazed, or periodically logged for wood, how to sustain Earth’s soils is becoming a major scientific and policy issue,” Daniel Richter, a soil scientist at Duke University said. “Society’s most important scientific questions include the future of Earth’s soil.”
The name, Anthropocene, was coined in an off-the-cuff remark, by the Nobel prize-winning chemist, Paul Crutzen, in 2002. He suggested that the environmental effect of increased human population and economic development meant the Earth was entering a new era. But scientists want to redefine our epoch to reflect humanity’s impact on the planet. AGENCIES