The Icelandic Road and Coastal Administration has closed roads and banned hiking in a large area north of the Bardarbunga volcano.
The black hatched area on the map below shows the region that is out of bounds:
The organisation warns of a "danger of flooding in connection with a possible volcano eruption".
More top news
The singer ended speculation over who would perform by saying "the rumors are true" to her 63 million Twitter followers on Friday morning.
There will be lighter winds for all of us than yesterday, although it will still feel cool.
Senior fashion analyst at Mintel Tamara Sender said: "For the first time ever sales of trainers have overtaken high heels."