  Rift plays an important role in ice shelf calving event, which forms the
boundary of tabular detachments and the acts as precursor for ice shelf
calving. Rift m\'elange shows the resistance to deform during rift propagation,
which plays the role as stabilizing the rift. However, the detailed 3D
propagation process of the rift, including the dynamics motion of its
m\'elange, is not clearly investigated since then. In this paper, a long time
series of 2D propagation rates are generated to provide an overview of all
rifts throughout the FRIS, which reveals that the rift T1 and T2 were quite
active and will dominate the next calving event. Then, the process of widening
of rift T1 is detailed investigated, which is representative for rift
propagation process. By utilizing REMA DEMs and ITS_LIVE ice velocity maps, the
process of m\'elange widening and rift wall widening are estimated. The
m\'elange widens linearly in space and rift wall widening is caused by
collapse. The processes of m\'elange height decreasing and m\'elange widening
both reveal linear patterns during rift widening process. Rift widening process
shows seasonal variant, which is attributed to the seasonal variant of rift
wall widening. However, m\'elange widening reveals a stable trend, which proves
its stability. The seasonal variant of rift wall widening is further explained
by the collapsing process during different seasons. The process of rift
propagation worth long-term monitoring both vertically and horizontally in the
future, which is significant for ice shelf calving ice shelf instability
studies.

Geophysics