Uh oh: The rift that's about to cleave off a massive Antarctic iceberg has a sibling

Scientists keeping close watch on the Larsen C Ice Shelf in Antarctica have noticed something new: The rift, which has been opening across the shelf for some time, now has a sibling. 
Using a highly-sensitive European Space Agency satellite known as Sentinel-1, scientists have been tracking the progress of a lengthening and widening crack across the floating Larsen C Ice Shelf. Once this crack reaches a certain point — exactly when is unclear — it could break off one of the larg