Lava samples have revealed a surprising discovery about the geological makeup of the Earth’s crust and could have implications for volcanic eruption early warning systems, a University of Queensland led study has found.
It was previously understood that cooled lava from so-called ‘hot spot’ volcanoes was pristine magma from the melting mantle, tens of kilometers under the Earth’s surface, but this is now believed to be not true.
‘For decades, we have considered hot spot volcanoes to be messengers from the Earth’s mantle, offering us a glimpse into what’s happening deep under our feet,’ said Dr. Teresa Ubide, author of the study.
“But these volcanoes are extremely complex inside and filter a very different melt to the surface than what we’ve been expecting.
“This is due to the volcano’s intricate plumbing system that forces many minerals in the magma to crystallize.”
Dr. Ubide said the minerals are being recycled by the rising magma, changing their overall chemistry to “appear” pristine, which is an important new piece of the puzzle to better understand how ocean island volcanoes work.
“We have discovered that hot spot volcanoes filter their melts to become highly eruptible at the base of the Earth’s crust, situated several kilometers below the volcano,” she said.
“The close monitoring of volcanoes can indicate when magma reaches the base of the crust, where this filtering process reaches the ‘tipping point’ that leads to eruption.
“Our results support the notion that detection of magma at the crust-mantle boundary could indicate an upcoming eruption.
https://phys.org/news/2021-09-lies-beneath-volcanic-secrets-revealed.html