Source of Volcanic Eruptions Closer to the Surface Than Previously Thought

The source of volcanic eruptions seems to be closer to the surface than previously thought, according to a new study that challenges the conventional view of how these phenomena occur.

Scientists have long-believed that volcanoes come from deep within the interior of the planet, when tectonic plates that make up the Earth's crust shift and release heat. But researchers Don L. Anderson, of the California Institute of Technology, and Scott King at Virginia Tech, beg to differ.

This duo argues that the heat volcanoes spew out is closer to the surface than you think - about 80 kilometers (50 miles) to 200 kilometers (124 miles) deep to be exact. This region is known as the asthenosphere, the layer above the Earth's mantle.

"For nearly 40 years there has been a debate over a theory that volcanic island chains, such as Hawaii, have been formed by the interaction between plates at the surface and plumes of hot material that rise from the core-mantle boundary nearly 1,800 miles below the Earth's surface," King said in a press release. "Our paper shows that a hot layer beneath the plates may explain the origin of mid-plate volcanoes without resorting to deep conduits from halfway to the center of the Earth."

Traditionally, the asthenosphere has been viewed as a passive structure that separates the moving tectonic plates from the mantle. And as the tectonic plates sink as the Earth cools, they displace warmer material deep within the interior that eventually shoots out of the volcano as the steaming hot magma we see during an eruption.

However, the work of Anderson and King indicates that the hot, weak region beneath the plates acts as a lubricating layer, preventing the plates from dragging the material with them deeper into Earth's core.

And according to their study, the fact that the tectonic plates don't cause heat to rise isn't a problem, for the lubricating layer is the hottest part of the mantle.

"We're taking the position that plate tectonics and mid-plate volcanoes are the natural results of processes in the plates and the layer beneath them," King added.

Regardless of how they're created, volcanoes play an important part in the Earth's environment, and may even help to mitigate climate change thanks to the aerosols they release during an eruption, which reflect solar radiation back into space.

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