The rift of Pine Island Glacier's floating tongue is a cause of concern among glaciologists because it suggests that this part of the ice shelf is not stable and may collapse in the future. As explained in this EOS article 
Rifts usually form at the sides of an ice shelf where the ice is thin and subject to shearing that rips it apart. But this particular rift originated in the center of Pine Island Glacier’s ice shelf and propagated out to the margins.This implies that something weakened the center of the ice shelf. The most likely explanation is that a crevasse melted out at the bedrock level, driven by a warming ocean, according to the researchers."
Online survey: can we detect an expansion of the rift on the Sentinel-2 images only?
 Lipuma, L. (2017), West Antarctic ice shelf breaking up from the inside out, Eos, 98, doi:10.1029/2017EO064743. Published on 04 January 2017