A powerful volcano, Bárðarbunga, might erupt in the Highlands of Iceland. The Icelandic Met Office has upgraded its aviation alert status to orange, meaning that a "volcano shows heightened or escalating unrest with increased potential of eruption." Seismic activity is often the precursor of an eruption.
The orange alert is the second highest alert status. The next alert level, red, means that an eruption is either imminent or in progress. Bárðarbunga last erupted in 1996.
According to the website of the Icelandic Met Office: "the intense seismic activity that started on 16th of August at Bárðarbunga persists. Very strong indications of ongoing magma movement, in connection with dyke intrusion, is corroborated by GPS measurements. There are currently two swarms: one to the E of Bárðarbunga caldera and one at the edge of Dyngjujökull just E of Kistufell. At 2.37 am on the 18th a strong earthquake (M4) was located in the Kistufell swarm.