The Earth’s Newest Secret: Fundamental Changes to What We Know About How Volcanoes Work

Rarely do we learn something that substantially alters the way we perceive the world. However, a similar realization has now come to Matthew Jackson, an earth scientist at the University of California, Santa Barbara, and the thousands of volcanologists throughout the world.

In the two centuries that scientists have been studying volcanoes, Jackson and his colleagues discovered a process that was significantly more active than anyone had anticipated while sampling magma from the Icelandic Fagradalsfjall volcano.

"We receive a tremendous surprise just when I believe we've gotten close to understanding how these volcanoes work," he added.

A tuya volcano called Fagradalsfjall was created during the Last Glacial Period on Iceland's Reykjanes Peninsula, around 25 miles (40 km) from Reykjavk.

Jackson was in the right place at the right time to see the formation of Fagradalsfjall, a fissure in the lowlands of southwest Iceland that split and erupted with magma in March 2021, thanks to a sabbatical, a pandemic, and 780 years of underground rock melting. Everyone on the Reykjanes Peninsula was prepared for an eruption by that point, he claimed.                                                                       

He described the 50,000 or more earthquakes, some of which had a magnitude of 4 or higher, that rattled the earth for weeks and kept the majority of Icelanders on edge as "the earthquake swarm."

The lack of sleep was worthwhile, though, and soon the irritability gave way to interest as lava boiled up and spattered from the hole in the earth of the rather unpopulated Geldingadalur district. Scientists and tourists rushed to the region to observe the formation of the newest portion of the Earth's crust. Due to the lava's slow flow and strong winds that carried the toxic fumes away, they were able to go near enough to the lava right immediately to regularly sample it.

The geologists at the University of Iceland, under the direction of Saemundur Halldórsson, were interested in learning "how deep in the mantle the magma originated, how far below the surface it was stored prior to the eruption, and what was happening in the reservoir both before and during the eruption." Even though they seem basic, these kind of inquiries present some of the greatest difficulties for volcanologists. This is because many active sites are located in distant areas and are difficult to access, dangerous and harsh circumstances, and unpredictable eruptions.

The idea, according to Jackson, "was that a magma chamber fills up gradually over time, and the magma gets thoroughly mixed." "And after that, it drains throughout the eruption." He went on to say that because of this well-defined two-step process, scientists who research volcanic eruptions don't anticipate seeing much of a change in the chemical makeup of the magma as it emerges through the earth.

But in Iceland, the rates of change for important chemical indicators were more than a factor of 1,000 higher, Jackson said. More compositional variety was displayed by the Fagradalsfjall eruption in a month than the Klauea eruptions had in decades. The complete spectrum of chemical compositions that have ever erupted in southwest Iceland in the last 10,000 years was represented by the samples taken during this eruption during the duration of the first month.

According to the researchers, this fluctuation is a result of subsequent batches of magma moving into the chamber from deeper in the mantle.

Imagine a lava light in your head, Jackson instructed. "At the bottom, there is a hot lamp that heats up a glob, which rises, cools, and finally sinks. From the Earth's core's surface to its interior beneath the tectonic plates, the mantle behaves somewhat like a lava lamp. Then, he continued, molten rock from these plumes accumulated in chambers and crystallized, gases leaked through the crust, and pressure increased until the magma found a way to escape. As the heat causes regions of the mantle to rise and plumes to form and move buoyantly upward toward the surface, molten rock from these plumes crystallized.

"We receive a tremendous surprise just when I believe we've gotten close to understanding how these volcanoes work," Jackson, Matthew

According to the article, the expected "depleted" magma type that had been building up in the reservoir, which is about 10 miles (16 km) below the surface, is what erupted for the first few weeks. By April, though, it was clear from the data that the chamber was being refilled with deeper, "enriched" melts of a different makeup. These came from a different area of the Icelandic upwelling mantle plume. More magnesium and carbon dioxide gas were present in this new magma, which had a less altered chemical make-up. This suggested that fewer gases had escaped from this deeper magma. The deeper, richer form of magma that dominated the flow by May. They claim that "never previously have these quick, severe variations in magma composition at a plume-fed hotspot been seen in nearly real-time."

However, Jackson claimed that these compositional alterations might not be as uncommon. Simply put, it's uncommon to have the chance to sample eruptions at such a young stage. For instance, the most recent eruptions on Iceland's Reykjanes peninsula happened eight centuries ago, before the 2021 Fagradalsfjall eruption. He believes that this recent activity in southwest Iceland heralds the beginning of a fresh volcanic cycle that might last for centuries.

Because lava flows from the latter stages bury the early stages of most eruptions, he explained, "we frequently don't have a record of them." The researchers claim that this effort gave them the opportunity to observe a phenomenon that was thought to be feasible but had never been seen in person.

This finding gives the scientists with a "key limitation" on how they will construct models of volcanoes all around the planet. However, it is still unclear how typical of other volcanoes this phenomena is or how it contributes to eruptions. It serves as a reminder to Jackson that the Earth still has mysteries to reveal.

So, he continued, "it'll constantly be on my mind: This might not be the whole account of the eruption when I go out to sample an old lava flow, or when I read or publish studies in the future.                                                                                                                                                                                                By UNIVERSITY OF CALIFORNIA - SANTA BARBARA