The Grimsvotn volcano erupted Saturday in Reykjavik, Iceland. This is Iceland’s most active volcano and it has forced the closure of the main international airport and all domestic flights have been cancelled. Last year, ash clouds from another Icelandic volcano, Eyjafjallajokul led to the closure of a large section of European airspace, with repercussions for flights from the U.S. Matthew Roberts from the Iceland Meteorological Office has been monitoring the erupting volcano.