Updated

Iceland's Meteorological Office has raised the aviation alert level around the Katla volcano because of seismic activity.

The activity, which began Thursday and continued Friday, prompted officials to raise the alert level to yellow, which signifies volcanic activity above background levels. There are two higher levels of alert. Officials say they raised the alert due to "the unusually high level of unrest at the Katla volcano."

Katla is in southern Iceland, 140 kilometers (87 miles) from the capital, Reykjavik.

Civil Defense officials met Friday and said they've begun contingency planning to prepare for any eruption.

Iceland is often hit by seismic activity. Its volcanos attracted international attention in April 2010, when ash from an eruption of its Eyjafjallajokull volcano grounded flights across Europe for days, stranding millions of people.