Update on breaking news
It looks now as it is small eruption in Geldingadalur in Fagradalsfjall is like last night. No eruption occurs now. “There is still a lava flow going on, so it is not completely finished but it is not big,” said Hulda Rós Helgadóttir, a nature conservation specialist at the Icelandic Meteorological Office.
The extent of the eruption is small, and activity has decreased somewhat since last night. There are few magma jets from the fissure and the lava flow covers an area that is at most about 100 meters wide. As things stand now, the eruption is limited to a very small area in a valley, and it is very unlikely that lava flow will cause damage. No volcanic ash is detected from the volcanoes and based on initial estimates, there is not a high risk that gas pollution will cause great inconvenience except close to the eruptions.
The last eruption on the Reykjanes peninsula ended in the middle of the Sturlung Age, in 1240. There had been eruptions in the Reykjanes system since 1210, with several years of breaks. Among them was an eruption that began in 1226, six years after Snorri Sturluson returned from Norway, and was probably the largest eruption in the cluster. The Oddaverjaannál mentions this eruption and talks about “sandfall winter in Iceland.” The website eldgos.is says that the eruption in the cluster from 1210 – 1240 have the name of Reykjaneseldar.
The last eruption on the Reykjanes peninsula lasted for 30 years. It was also the final phase of an even longer volcanic eruption period on the Reykjanes peninsula, which lasted for 290 years. The last eruption in Fagradalsfjall was more than 6,000 years ago. Then the Beinavörðuhraun flowed. (Bone Guard lava.)
Now this eruption does not affect any buildings or internal infrastructure, there is a risk of gas formation from the eruption but mostly next the eruption, Air traffic runs normally and there is no ash coming from the volcano since it is a small eruption.
You can see in live webcam from the eruption here