Hotspot volcanoes

Our understanding of volcanoes has undergone a revolutionary change

What we thought we knew about volcanoes before the recent revelations of Fagradalsfjall eruptions in Iceland, is now radically different. It is not often that we acquire knowledge that revolutionizes our view of the world. Such an epiphany, however, has just been revealed to Earth scientist Matthew Jackson of the University of California, Santa Barbara and hundreds of volcanologists around the world.

The geologists, led by Saemundur Halldórsson of the University of Iceland, sought to determine where in the mantle the magma had formed, how far below the surface it had been stored before the eruption and what had happened. passed through the reservoir before and during the eruption. These questions may seem basic, but they pose some of the greatest challenges for volcanologists. Indeed, many active sites are located in inaccessible, dangerous and isolated areas, and eruptions can occur at any time.

According to the article, during the first few weeks, the type of depleted magma that had accumulated in the reservoir about 16 km below the surface was what erupted. In April, however, it became clear that a new, deeper and richer form of melt was recharging the chamber. These came from a separate section of the Icelandic mantle plume upwelling zone. This new magma had a higher level of magnesium and a higher amount of carbon dioxide, indicating a less altered chemical composition. As a result, it seemed less gas was released from the magma at these greater depths. By May, deeper and richer magma had become the dominant flow. They claim that never before have such rapid and severe variations in magma composition been observed in near real time at such a hot spot.

This discovery represents a “key boundary” for scientists as they develop models of volcanoes all around the planet. However, it is still unclear how often this phenomenon occurs or what role it plays in triggering an eruption on other volcanoes.