In the last four years the Reykjanes peninsulalocated in South-west of Icelandwas affected by Ben 12 volcanic eruptions (of which the most recent occurred in the night between 15 and 16 July), after Ben 800 years of quiescence. In Iceland, eruptions are frequent, since the island is on the Middle-Atlantic backbone Along which the North American plaque and the Eurasian one move away from each other, but in this peninsula they did not see them from 8 centuries. Why then then a sudden awakening? In the area volcanic activity has a cyclical trend: about every 1000 years you have 200-500 years of volcanic eruptions quite frequent. This is because in the area the rocks, subjected to enormous efforts due to the movement of the plates, after a certain time they break originating cracks that facilitate the ascent of magma on the surface. According to experts, the eruptions in the peninsula could also follow each other for decades.
The geological context of the Reykjanes peninsula
The Reykjanes peninsula is located in Western Rift area of Iceland, also known as Area of Rift Reykjanes-Langjökull. It is an area about 30 km long and 5-6 km widely located in correspondence with a depressing, called Rift Valleywhich crosses all Iceland. This continuation also continues on the ocean seabed, along the crest of the Middle-Atlantic backbonewhich is a submerged inception of the seabed of which Iceland constitutes an emerged portion. Inside the reykjanes peninsula area there is a volcanic system consisting of fractures Also long dozens of kilometers and with so-in orientation, aligned with the medium-Atlantic ridge.
These cracks represent one preferential way for the ascent of magma Up to the surface, where there are volcanic eruptions of basaltic and very fluid lava capable of expanding on large areas. To cause magma to escape in correspondence with the peninsula, and in general in Iceland, is themutual removal between the North American and Eurasian plates along the oceanal ridge. The quantity of magma is particularly high, so much so that it has allowed the emergence of the island 20 million years ago, also thanks to the presence under the Iceland of a hot pointthat is, of a restricted area in correspondence of which columns of magma continually date back from the cloak. These phenomena make eruptions in Iceland very frequent, but in the Reykjanes peninsula they have not occurred for 800 years, while in the last four years the volcanic events have even been 12.
Because the eruptions have started again in the Reykjanes peninsula
The rocks of the Reykjanes peninsula have revealed that thevolcanic activity of the area has a cyclical trend. The last three periods of volcanic activity have occurred On average every 1000 years: the oldest one has to testify to dates back to 3200 years agowhile the subsequent episodes occurred 2000 years ago and in XIII century. These phases are characterized by Eruptions that follow one another for 200-500 yearswhose testimonies are found in the form of solidified lava flows: on the flows of 800 years ago, for example, nearby Reykjavik was built. This cyclical trend is caused by the accumulation of energy by the rocks subjected to enormous tectonic efforts, which is periodically released with the reactivation of faults and theopening of new cracks from which magma can escape.
As Professor Tamsin Mather, of the University of Oxford says, the phenomenon is also due to the fact that the plaques “They are separating approximately at the speed with which the nails grow, therefore a few centimeters per year, but they do not seem to separate fluidly”. The speed of removalMeaning what, it is not constant And when increasing the rocks, they fracture more easily by originating earthquakes. The magma present in the subsoil dates back through these fractures and fills them: so large and deep accumulations are formed, called called dicchi. Inside the magma exerts a pressure that periodically manages to open the fracture to the surface, generating a volcanic eruption. When the pressure decreases, the rocks surrounding the magma in ascent are broken and close the fracture. The magma tank, however, continues to be fed by another magma coming from the cloak and therefore after some time the pressure in the fracture causes another eruption to take place.
What will be the evolution of volcanic eruptions in Iceland
Based on the cyclical trend of the volcanic activity of the Reykjanes peninsula, we must expect decades of volcanic eruptions of relatively short duration, interspersed with more or less long breaks. The monitoring of the movements of the magma in the subsoil is constant and SISMI preceding eruptions are a significant signal, but foreseeing exactly where and when the next eruption will occur it is very difficult. In the future, existing fractures could reactivate, but also open new ones. Such an intense volcanic activity, even if effusive, could constitute a problem for the peninsula, since most of the Icelandic population focuses here.
