I slap myself on the head: this collapse has been visible for most of July.
Let's keep an eye then on the new crack, top center below. The fact remains, even if Sentinel scenes are auto-streamed into a video, somebody has got to watch that video. However it's feasible to set up an auto-alert by differencing frames, not so dissimilar to wildlife camera motion detectors.
Followed by auto-posting and subsequent Typepad notifications, maybe in the future an auto-journal submission that robotic crawling could utilize use for review articles, future sea level rise revisions and proportionate auto-increasing of carbon taxes.
Do you have earlier frames handy? To date the new crack, see when it developed, whether it is progressing. Also one longitudinal crack, bottom left, seems to pre-date the horizontal developments.
It is parallel to the main one because there is more frictional drag on the right side, meaning transverse shear leading to brittle failure. Petermann also has this half-herringbone pattern. The ice in the middle perhaps has a different character, maybe colder. The whitish areas on the sides where motion transitions from 3/12 pixels a day to 0 might be warmer, softer, smoother so more reflective of the radar beam.
In glaciology, they would go on here about the Cauchy stress tensor, deviatoric stress component, strain rates and so forth. It's all in Cuffey & Paterson or at this user-friendly Antarctic link below. There was a nice graphical display on that recently for Larsen B.
http://www.antarcticglaciers.org/modern-glaciers/longitudinal-stress/Fascinating to watch how gaps in the crack get filled in. The piece about to shatter is pivoting, somewhat awkwardly, causing secondary longitudinal cracks to extend on the right side. Here is a shorter smaller faster version of W's animation for any busy ice executives who might stop by.