A new, unexplained crack has formed in the middle of a Greenland glacier, in sight of a larger fissure that has been creeping from the outer edge inwards, The Washington Post reports. NASA’s Operation IceBridge spotted the crack while flying over the Petermann Glacier, which connects the Arctic Ocean in the north to the Greenland ice sheet in the south. That glacier has already lost about 388 square kilometers of ice from two collapses in 2010 and 2012. It is unclear at this point how precarious the new crack is, but if part of the ice shelf does fall off because of the break, it could form a new 129 to 181–square-kilometer ice island. The team posted the photos to Facebook last Friday.