Evidence from Hawaii and Iceland has indicated that the Earth may literally have a heartbeat, in the sense that the planet’s core may be dispatching simultaneous plumes of magma towards the surface every 15 million years or so.
According to a report in New Scientist, if the hypothesis is true, it would revolutionize our ideas of what’s happening far below our feet.
Rolf Mjelde of the University of Bergen and Jan Inge Faleide of the University of Oslo, both in Norway, used seismological data to measure the thickness of Earth’s crust between Iceland and Greenland.
Iceland is on the Mid-Atlantic Ridge, where magma wells up to form fresh crust.
The measurements allowed Mjelde and Faleide to infer the past flow of magma in the plume generally thought to rise beneath Iceland.
When this plume is strong, it thickens the crust that it forms at the surface.
They found that the crust has thickened roughly every 15 million years, suggesting the plume pulses at around that frequency.
Regular pulsing of plumes is not a new idea, but when the pair compared their results with similar pulsing in Hawaii, which also sits on a plume, they found a surprising correlation.
Data collected by Emily Van Ark and Jian Lin of the Woods Hole Oceanographic Institution, Massachusetts, suggests that Hawaii’s plume pulses have coincided with Iceland’s.
“These two are on very different parts of the Earth, so I don’t think the synchrony could be related to something in the mantle,” said Mjelde. “It must relate to the core somehow. I can’t see any other possibility,” he added.
This would mean that the Earth’s core periodically heats up the overlying mantle, generating synchronized plumes that rise to the surface at widely separated spots.
“If correct, it would be a significant alteration from our current thoughts,” said Rhodri Davies of Imperial College London.
Most geologists who believe that mantle plumes exist think that pulsing can be explained by processes in the mantle alone, such as magma build-up in regions of different viscosity.
“A new way of thinking would be needed,” said Mjelde. (ANI)