An Icelandic volcano may be about to wreak havoc on Europe.

Bárðarbunga, Iceland’s largest volcano, is being pummeled by earthquakes. That means pressure is building, inflating the volcano and increasing the chance that it will erupt. The 6,500-foot-tall volcano sits beneath Europe's largest ice cap so any eruption could be particularly explosive, producing large amounts of ash.

This has happened before. In 2010, Eyjafjallajökull’s massive ash cloud affected millions of travelers across Europe for weeks. Bárðarbunga’s last eruption in 2015 was one of the largest in Iceland’s history. Scientists believe another eruption is coming — but it could be some time before it's ready to blow.