
Volcanoes are often described as rivers of lava flowing into the ocean. But it’s also possible that volcanic eruptions can also take place underwater. Last year, researchers disclosed that magma, the molten rock, surged beneath an Icelandic fishing village at an extraordinary rate. This development has sparked concerns about the possibility of the region entering a new volcanic era.
The discovery coincides with the Reykjanes peninsula’s latest volcanic eruption, marking the third fissure on the island since December. The first eruption saw lava spewed across Grindavik, forcing residents to flee their homes. The second eruption saw lava break through defense walls around the town, destroying buildings in its path.
But the most recent eruption, which began early Thursday, was different because it didn’t produce an ash cloud. This meant that it was unlikely to disrupt air travel, unlike the 2010 eruption, which halted flights for days because of concerns that ash could damage jet engines.
Regardless, Iceland’s latest eruption marks the beginning of a new volcanic era. Scientists predict that the Reykjanes peninsula may witness several such eruptions. The island sits over a “hot spot” on the boundary between two of the world’s most enormous tectonic plates. This means it’s one of Earth’s most geologically active regions.
This new volcanic activity is likely to be short-lived, however. The magma that fuels the eruptions has been accumulating deep underground for centuries, and it has to rise through the crust to cause volcanic eruptions. Magma is a thick liquid of partially melted rock made of silica (SiO2) and other minerals. It rises through cracks in the Earth’s crust caused by an earthquake or magma building pressure beneath the surface.
As magma rises through the crust, it cools and separates into different crystal types. Like basalt, magmas with higher silica content form dark, smoky minerals such as pyroxene and plagioclase. Magmas with lower silica, like andesite, form lighter, more crystalline minerals such as olivine and feldspar. The differences in the crystal types allow geologists to identify magma types.
Once magma reaches the surface, it can be erupted as lava or spewed out as a volcanic cloud. Lava is hot and molten, while volcanic clouds are composed of fine dust that can make breathing difficult.
This week’s eruption has forced local authorities to declare an emergency, and the country’s prime minister has warned that residents should prepare for an extended stay away from their homes. The government is urging residents to stock up on food and supplies, and it’s reportedly working to bring more electric heaters to the area. Despite the crisis, many residents are reluctant to return to their homes. Some have told the BBC that they don’t expect to be able to live there again.