Preamble: I must admit that the use of the term "Destruction Zone", which I had accepted, was a bit disturbing to me. After a first reading, diagonally (for the moment), of Stef Lhermitte et al. 2020, I found the term "Damage Zone", which seems to me better (and whose acronym is the same).
The other thing that disturbed me was the use only of the direction from the center of the Ice Shelf relative to the PIG, for example north side: NEDZ and NWDZ.
I propose to distinguish them by using the indications "upstream" and "downstream" (which really characterizes it), which gives: NuDZ, NdDZ, SuDZ and SdDZ.
About Stef Lhermitte et al. 2020, there are two sentences that leave me rather perplexed:
> “In the northern shear zone of PIG, on the other hand, the observed damage evolution is absent or lim-ited due negative maximum strain rates (Fig. 1A) that result in closing of crevasses and rifts.”
> "whereas the north-ern shear zone remained largely intact after the unprecedented retreat and disconnection from the northern PIG ice shelf in2015 (6)"
But it is true that this article was written in 2018 that for the PIG already seems so far away...
Indeed, as many have commented here, there is in fact a NuDZ and, as we have seen since the big calving in February, there is actually a NdDZ!
A few months ago we thought (we hope) that the very narrow NE-IS, supported by the Ice Rise Evan's Knoll, could provide, at least temporarily, a pinning point to the PIG. It seems that this will not be the case.
Analysis :
> the speed of the PIG is very high
> the NE-IS is fed by ice from the PIG basin which, to the right of the main flow, overflows an Ice Rumple and by a small tributary to the north.
> the ice of this ice shelf, in the strip near the NSM, moves parallel to the PIG with a very high velocity gradient
> downstream the NE-IS becomes very narrow
Currently this gives very high stresses with the PIG on the one hand and with the stationary ice of the Ice Rumble Evan's Knoll on the other hand. And the remaining part of the NE-IS downstream of the separation with the PIG cannot provide support to the NE-IS upstream: the shock cannot be absorbed by deformation and it tends to break and calve.
And the NE-IS is a funnel and further upstream will widen which should make things worse.
I don't see what could prevent the NdDZ from gradually expanding upstream until it reconnects to the NuDZ. One can hope that this process will be slow (slower than at present), but it is only a matter of a few years.
And the speed of the PIG is likely to increase with the reduction of lateral stress, which is not conducive to stability.
Things are not better in the south, but this will be for another post.
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