Thinking more about the lateral compression, it seems that there is a compression from the opposite side, a bit further down. This pushed the calving face to the river right, after passing Evans Knoll.
I suspect, but can't prove, that this deformation force increases the backpressure on the rest of the glacier, as it forces the visible bend to the river right.
I suspect that this deformation was part of the reason the calving broke off the way it did (first the river right, the the river left last, as it was in compression for the longest). I think this may be a protective factor, decreasing the chance of a large calving soon. I hope.
I worry about the rate of decline once the calving front passes those lateral pinning points. That's when it'll really start flying.
A is the compression force due to Evans Knoll, B is the one on the opposite, causing the flexion around Evans Knoll.
I was surprised that PIG didn't go this summer, but it still looks like it can go at any time, as we are seeing increasing amounts of minor calving at the notches to either side of PIG.
I believe the compression from the SW Trib described above is keeping it penned in. There is a good image on that post, worth going back to review.
Click to animate and zoom in for a closer look. Dates are 23 Mar to 16 Apr.http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20170416T042746_5C37_S_1.final.jpg