1. Bárðarbunga lies in central Iceland, rises to 2009 meters above sea level and is the country's second highest mountain. It is completely covered by the Vatna Glacier and is part of Iceland's largest volcanic system, which comprises several volcanoes and is 190 kilometers long.

2. Iceland's Meteorological Office has detected more than 2000 earthquakes in the Bárðarbunga area - at a depth of five to ten kilometers - since Saturday. Scientists see earthquakes as an early warning that a volcano may erupt. When magma moves deep down, the pressure breaks rocks and the earth starts to shake.

3. It's hard to say with any certainty whether Bárðarbunga will erupt. Researchers have very few data about this particular volcano. It is in a remote area and has only erupted a few times in the past. Volcano researchers at the GFZ Helmholtz Centre Potsdam say their statistics suggest that magma activity leads to a volcanic eruption in less than 10 percent of all cases.

4. The last time Bárðarbunga erupted was in 1996. Its biggest eruption was about 500 years ago. Researchers say it was one of the biggest volcano eruptions worldwide of the past 10,000 years.

5. Eyjafjallajökull is another volcano in Iceland. It erupted in 2010, causing an ash cloud to cover Europe. Eyjafjallajökull and Bárðarbunga have a lot in common. They were both created by the same tectonic activities underground. They are both covered with ice. They have many geological properties in common. And their magma lies at similar depths. But Bárðarbunga is much bigger than Eyjafjallajökull and would release a lot more magma.

6. When Eyjafjallajökull erupted in 2010, hot magma came into close contact with cold ice. When the water started to evaporate abruptly, an explosion occurred which tore magma and rocks apart - and an ash cloud formed. Due to the nature of the magma on Iceland, the ash particles were very small, and they stayed in the air for several days without coming down. As Bárðarbunga is also covered by a glacier - that is, frozen water - the same could happen, if indeed the volcano erupts.

7. Winds can transport an ash cloud from Iceland to the European mainland. It all depends on which direction the wind is blowing.

8. Planes are not allowed to fly through ash clouds. That's why so many flights were cancelled when Eyjafjallajökull erupted in 2010. Ash particles can harm a plane's engines. When the particles get into the burning chamber, they melt and settle permanently on the cooler blades. Eventually, the engine breaks down.

9. Eyjafjallajökull's eruption in 2010 had an enormous economic impact. It is estimated that the total loss for the airline industry was more than a billion euro. Iceland is said to have suffered several million euro in economic damage - farmers were hit especially hard.

10. In the event of Bárðarbunga erupting, the biggest threat to Iceland would be flooding. If Bárðarbunga erupts, magma could melt the glacier and send large amounts of water down into the valleys. The German researchers at Potsdam say it is a good thing that Iceland is keeping such a close eye on developments at Bárðarbunga. But there is no reason to panic, they say. Chances are, nothing will happen - apart from more earthquakes.