Experts have warned that an underground magma tunnel between a pair of Icelandic towns could erupt at any moment. But what will this eruption look like? And how far-reaching will its effects be?

Officials in Iceland are preparing for an imminent volcanic eruption from a submerged tunnel of magma, which could unleash superhot lava flows on nearby towns, a vital power plant and an iconic tourist destination.

The tunnel of molten rock, known as a magma dike, stretches for around 9.3 miles (15 kilometers) between Grindavík and Sundhnúk in Iceland’s Reykjanes Peninsula. The underground dike has triggered thousands of earthquakes and caused significant ground deformation that has opened up sinkholes in the surface and cracks in nearby buildings and roads. As a result, local residents have been evacuated.

But this is likely just the beginning.

The Icelandic Meteorological Association (IMO) has warned that a full-blown eruption is almost certainly on its way. And other experts have suggested that the eruption could be part of a more explosive, centuries-long eruption phase for the region.