At near 80°S, Slessor glacier tends largely east to west occupying a short trough near 2km deep extending around 100km in the confines of a valley section forged between the mountains of the Shakleton Range to the south and Theron Mountains to the north. The depths don't continue into the Filchner trough. Before joining the northward momentum of the Filchner trough, flow veers toward the south as bedrock becomes half as shallow at steep gradient. Inflow feed into Slessor is a chaotic squeeze. Ice flow enters sharply from vastly differing directions, and twists around in differing directions at different heights and depths and layers.
Higher ice long ago used to flow through at differing angles somewhat determined by, and somewhat determining the land mass distribution. Ice at different points at different times can be collecting matter, mineral or organic, fresh or fossil and carrying, or dispersing it quickly or slowly. Ice at different layers pushes in differing directions. Ice presses downward at points and ice lifts upward at points. It twists and turns and grinds and breaks. Water streams through and under different sections at different rates depending on temperatures, ice mass volume and velocity flow interaction to Earth mass. It seems that flow into Slessor Glacier had long earlier reduced and brought the ice elevation down enough to cause the bordering ice mass to spill heavy load across from above, raising the elevation back up.
The first animation is of NASA Worldview imagery from 2000 to 2023. With the wedge at the top middle half of the gif where a portion of the Theron Mountains is slightly visible on the left, land mass is submerged by very slow ice, much of which is perhaps hundreds of metres thick, with much of it reaching in excess of 1km high. It seems to be an ice rise largely held in place due to the counter momentum of slow flowing ice compacting up around against it. At the point of the ice deformations against it on the right, ice squeezes in on outer layers of the ice rise. It is becoming quite active with large displacement seen spilling south onto and into Slessor, near where the glacier runs a gradient down another couple of hundred metres to the Filchner Ice Shelf. The northern segment of the glacier is covered in similar such bulging thick ice all the way down through confining convergence with Bailey Ice Stream, where the sharp natural angle points. It is heavily constrained through bathymetry and counter flowing ice, having not gained access into the deep Filchner Trough like the more western veering lower Slessor segment.
The collecting thick bulging ice sector seems near motionless but may be building up toward potential velocity increase that could flow along across the top of Filchner in an avalanche pulling loads of continental ice mass down a new ice stream. If it gets thick enough along direct connecting gradient trajectory path between points low elevation west and high elevation east, ice can potentially swing down with the forces of gravity over the top from northward on the east and veering northward on the west cutting across the Bailey Ice Stream. Or if ice at the high point of Slessor continues to build up thick enough, ice could spill down on top of the main less restrained glacial bend to veer around more south, and westward. What could take decades, could take years. It's largely wait and see on how large weight on seas will be.
The second animation is zoomed out a bit further and has more spaced out dates. The third gif shows various times over 5 years with Sentinel 2L1C NDWI trying to get a rough view of bulging ice dynamic. The forth gif is further north with Bailey Ice Stream on the right. It compares two Sentinel 1, EW-HHHV images about 5 years apart. The pressure load is building out of shot to the lower right. Filcher crevices begin deeper south. Elevation seems to be lowering. Watch that space.
