Dear authors,

My apologies for my tardiness.
Both reviewers are quite positive about your contribution and made some good suggestions, that the authors have responded to appropriately.

I have a few minor comments that are related to the parameters obtained from the laboratory experiment:
1) In relation to the field experiment, the authors discuss the maximum value of H. The opposite is true for the laboratory experiment, here H is smaller than the smallest value derived from geometrical considerations by Niemeijer and Spiers (2007), i.e. (1/sqrt(3) / 2 phic). Can the authors comment on this?
2) The explanation for the difference between the obtained value for L and the value from microstructural observations. The authors claim that there is compaction after the end of shearing. This is not a very satisfactory explanation for two reasons: first, the authors assume that there is no time-dependent compaction. Second, a layer of 60 micron thick with 25% porosity can not compact down to a layer of 20 micron. One possibility is that the dilatancy modeled is for two layers (since it is a double-direct shear set-up), which would mean you could double the observed thickness of the PSZ (20 micron for each layer).

I hope this helps,

Andre

Dear authors,

We are happy to accept your manuscript for publication in the THMC Special Issue in Solid Earth. Thank you for submitting your work with us.

With best wishes,
Susanne Buiter