A giant iceberg the size of Greater London has broken off Antarctica. The mountain is close to the British Halley Research Station, which lies on the Brunt Ice Shelf. Sensors on the shelf confirmed the split late Sunday. Station staff are not in danger as they are 20 km from the rift known as Chasm One and will maintain their base and instruments until picked up next month. However, they had reduced their activities before the iceberg calved. The BAS team ensures that there are no unexpected instabilities in the remaining ice shelf platform on which the station is located. The UK base consists of a series of modules on skis that allow it to be moved away from the edge of the ice shelf – so work can resume once scientists are confident the ice shelf is stable. In 2017, Halley was shifted 14 miles “upstream” when Chasm One began showing signs of activity. Had that transfer not taken place, Halley would now be at risk on the iceberg. Estimates place the size of the new iceberg at about 600 square miles. Although climate change has worried scientists and has been blamed for other collapses in other parts of Antarctica, in this case the splitting is natural behavior for an ice shelf.