It's not every day that we learn something that changes how we see the world. Matthew Jackson is an earth scientist at UC Santa Barbara.
Scientists have been studying volcanoes for two centuries, but Jackson and his team discovered a process far more dynamic than they had thought.
He said that when they get close to figuring out how these volcanoes work, they get a big surprise.
Nature publishes the findings of the geologists.
Ten thousand years in a month.
Jackson was put in the right place and time to see the birth of Fagradalsfjall, a fissure in the lowlands of southwestIceland that split and exploded with magma in March 2021. He said that everyone on the Reykjanes Peninsula was prepared for an eruption.
He said that the swarm of earthquakes that shook the earth for weeks kept most of the population in fear.
The sleep deprivation was worth it, and crankiness turned into fascination as lava bubbled up and spattered from the hole in the ground. People from all over came to see the newest part of the Earth's crust. They were able to sample the lava from the beginning because of the winds blowing noxious gases away.
The unpredictability of the eruptions, the danger and extreme conditions, and the remoteness and inaccessibility of many active sites are some of the biggest challenges for those studying volcanoes.
Jackson said that the assumption was that the chamber would fill up slowly and that the magma would mix. Over the course of the eruption, it begins to drain. As a result of the two-step process, those studying volcanic eruptions don't expect to see much change in the chemical composition of the magma as it leaves the earth.
He said that this is what he sees at Mount Klauea. There will be eruptions for a long time and there will be small changes over time.
There was more than a factor of 1000 higher rates of change for key chemical indicators. The Klauea eruptions have shown more variability than the Fagradalsfjall eruption. Over the course of the first month of the eruption, the total range of chemical compositions that were taken was the entire range that has ever erupted in southwestIceland.
The scientists say that the variability is due to the flow of magma into the chamber.
Jackson told them to imagine a lava lamp. A hot bulb at the bottom causes a blob to rise and then sink. The Earth's mantle is similar to a lava lamp, operating from the top of the core to under the plates. He explained that when the heat causes the mantle to rise, molten rock accumulates in chambers and gases escape through the crust, until the magma finds a way to leave.
According to the paper, for the first few weeks, what erupted was the expected "depleted" magma type that had been accumulating in the area. The chamber was being recharged by deeper, "enriched" type melt with a different composition that came from a different region of the upwelling mantle. The new magma had a less modified chemical composition, with a higher magnesium content and a higher proportion of carbon dioxide gas. The magma that dominated the flow was enriched. They say that these changes in magma composition have never been observed before.
Jackson said that the opportunities to sample eruptions at such an early stage are not very frequent. The most recent eruptions on the Reykjanes peninsula took place eight centuries ago. He thinks that this new activity is the beginning of a new volcanic cycle.
The researchers were able to see for the first time a phenomenon that was thought to be possible but had never been seen.
It is not yet clear how representative this phenomenon is of other volcanoes, or what role it plays in triggering an eruption, though this result presents a "key constraint" for the scientists. It's a reminder that the Earth has secrets.
He said that when he goes out to sample an old lava flow, or when he reads a paper in the future, it will always be on his mind.
More information: Sæmundur A. Halldórsson et al, Rapid shifting of a deep magmatic source at Fagradalsfjall volcano, Iceland, Nature (2022). DOI: 10.1038/s41586-022-04981-x Journal information: Nature
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