A researcher explains: why volcanoes erupt in Iceland
Litli Hrutur belonging to the Fagradalfjall system erupted in July 2023. Valentin Troll was there to collect samples. Photo: Lukas Krmicek
In recent years, several volcanic eruptions have occurred on the south-western tip of Iceland: the Reykjanes Peninsula. Valentin Troll, Professor of Petrology and Geochemistry, researches volcanoes and closely follows their developments.
“There are five volcanic systems on the Reykjanes peninsula. The Fagradalfjall system and the Svartsengi system are the two that have had eruptions since 2021,” explains Troll.
From a geological point of view, Iceland is special. Firstly, it lies on the Mid-Atlantic Ridge, where the North American and Eurasian continental plates are moving apart at a rate of about two centimetres per year, causing volcanic eruptions on the ocean floor. But the main reason behind Iceland’s formation is what is known as a mantle plume, which lies directly under the island. It carries hot material from deep inside the Earth to the surface, where volcanoes are formed.
“The boundary between the Earth’s core and mantle is at a depth of 2,900 kilometres. From there, the mantle plume flows upwards, bringing with it hot mantle material from deep witin the Earth,” continues Troll.
Volcanic activity will continue
There are many indications that volcanic activity will continue on the Reykjanes Peninsula. In order to know what to expect, it is important to understand what is happening deep below the Earth’s surface where the magma collects.
“We are not entirely sure what is happening under the Reykjanes Peninsula. According to an early model, all material is coming up directly from the upper mantle. But that is a little problematic. It is difficult to understand why several volcanoes are active at the same time. The magma stream may be splitting,” explains Troll.
Another model that has been proposed is that there are several smaller magma chambers with various branches. This could explain why several systems are active.
“A third possibility is that there is a large magma chamber in the Earth’s crust that supplies several volcanoes with magma through a network of channels. If this is correct, we can expect many small, and possibly simulataneous volcanic eruptions in the coming weeks, months and years,” concludes Troll.
Åsa Malmberg