**7. Conclusions**

We obtained the post-seismic displacement field of the Kermanshah earthquake for the November 2017 to February 2020 time period, longer than previous studies (4 months for Barnhart's study, 7 months for Yang's study), from Sentinel-1 ascending and descending data. We came to the following conclusions:

For the first six months (until June 2018) the post-seismic displacement was due to the afterslip along the up-dip extension of the rupture zone. The moment released by afterslip was 12% of that released by coseismic slip. This was at the lower end of the observed range of afterslip durations and relative moment release. Possible explanations for little afterslip were the relatively low heat flow and pore-fluid pressures in the Zagros region.

For the subsequent period (we considered data until February 2020), the post-seismic displacement field was not consistent with afterslip but more consistent with viscoelastic relaxation in the lower crust. Assuming that this was the only process causing surface displacements, we found a best-fitting viscosity of η*lc* = 1+0.8 −0.4 × 10<sup>19</sup> Pas for lower crust. The data do not have the resolution to constrain the viscosity of the uppermost mantle but we could infer a lower bound of 0.6 × 10<sup>19</sup> Pas. A relatively strong lower crust and upper mantle was consistent with the relatively lower heat flow, low average Vp/Vs value and the existence of the upper mantle high-velocity anomalies in the Zagros region.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2072-4292/12/12/2032/s1: Figure S1: coseismic displacement field caused by the aftershock of 25 August 2018; Figure S2: uniform slip inversion result for afterslip for time period 2; Figure S3: conceptual model of the spatial relationship between coseismic fault slip and afterslip for time period 2; Figure S4: sampled data used for modelling of aftershock sequence 1 and aftershock sequence 2; Figure S5: same as Figure S4 but for time period 1 and time period 2; Table S1: reported ratio of the afterslip moment release relative to the coseismic moment release and the position of afterslip relative to the coseismic slip; Table S2: rheologic structures inferred in previous studies; Table S3: range, optimal and uncertainties of InSAR-inversion fault slip parameters for the afterslip for time period 2.

**Author Contributions:** Funding acquisition, S.Y., M.L. and C.X.; investigation, X.L.; methodology, X.L. and F.A.; software, X.L.; supervision, F.A. and Y.S.; writing–original draft, X.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Key Research and Development Program of China: Construction and Demonstration of Accurate Emergency Service System for aerial-space-ground based cooperative remote sensing, gran<sup>t</sup> number Y6A0022010, and the National Science Foundation of China, gran<sup>t</sup> number 41431174.

**Acknowledgments:** We would like to thank the anonymous reviewers for their helpful suggestions, which improved the quality of this manuscript.

**Conflicts of Interest:** The authors declare no conflicts of interest.
