A volcanic eruption at Stromboli, Italy, is a timely reminder of the almost unparalleled power of volcanoes. Spewing ash high into the sky, the Stromboli volcanic eruption has caused terrified tourists to flee, with some throwing themselves into the sea. Volcano eruptions remain almost totally impossible to predict, partly because of the trouble determining just how volatile a volcano’s magma is. However, a groundbreaking new scientific study has uncovered a surprising link between rainfall and magma, improving our understanding of this molten rock.
Volatile elements in magma, primarily water, drive explosive volcanic eruptions.
If more water is going down into the mantle, more needs to be coming out back into Earth’s crust
The tricky part is assessing how much of the volatile content was present in a volcano before an eruption occurs.
This is particularly difficult when the only evidence scientists can assess is the end product after all the material has been fired from a volcano.
New research from Washington University offers compelling evidence volcanic magma could be wetter than anticipated.
The most common method for determining volatile content requires studying melt inclusions – small bits of magma trapped inside lava once erupted.
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Melt inclusions provide a unique record of the physical and chemical processes operating in active volcanic magma chambers.
Seismologists study these glassy inclusions to understand the amount of hydrogen present, which can indicate how much water was dissolved in the magma in Earth’s crust before a volcano erupted.
This method is generally accepted as an accurate lower limit on volatile content, accounting for water lost during the explosion.
The latest study instead decided to examine the upper limit – something that had never been experimentally investigated before.
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Professor Michael Krawczynski, the study’s lead author, said: “What people have never looked at before and what we are trying to measure now is, how big is this bucket?
”You can imagine if it rained a lot, and your rain gauge was full, then you don’t really know how much it rained.
“It could have rained more! We just can’t say.”
To study the magma this way, the Washington University researchers created synthetic melt inclusions in the lab to figure out how much water a melt possibly could hold.
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Volcano eruptions: The trouble is determining just how volatile a volcano’s magma is (Image: Getty)
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They did this by replicating the temperature and pressure conditions that exist 24 miles (40km) below the Earth’s surface.
They next melted and rapidly cooled the sample and calculated whether their experiment had created a glass.
They continued the process, adding more and more water to the sample until the sample could no longer be quenched to form a glass.
Maxim Gavrilenko, a former postdoctoral fellow, said: “We found out that if you have a lot of water, then eventually you don’t have a glass.”
The researchers’ results align with recent work by Professor Douglas Wiens, who concluded as much as four times more water might be forced downwards, or subduct, into Earth’s mantle than previously thought.
Professor Krawczynski said: ”If more is going down into the mantle, more needs to be coming out back into Earth’s crust.
“That is what we are looking at here. We’ve understood that it is a cycle that needs to be balanced, but we have not had a good grasp of the sizes of the different reservoirs.”