*Article* **Rheology of the Zagros Lithosphere from Post-Seismic Deformation of the 2017 Mw7.3 Kermanshah, Iraq, Earthquake**

#### **Xiaoran Lv 1,2, Falk Amelung 3, Yun Shao 1,2,4,\*, Shu Ye 1,2, Ming Liu 4 and Chou Xie 1,2,4**


Received: 26 May 2020; Accepted: 23 June 2020; Published: 24 June 2020

**Abstract:** We use 2018–2020 Sentinel-1 InSAR time series data to study post-seismic deformation processes following the 2017 Mw 7.3 Kermanshah, Iraq earthquake. We remove displacements caused by two large aftershock sequences from the displacement field. We find that for a six month period the response is dominated by afterslip along the up-dip extension of the coseismic rupture zone, producing up to 6 cm of radar line-of-sight displacements. The moment magnitude of afterslip is Mw 5.9 or 12% of the mainshock moment. After that period, the displacement field is best explained by viscoelastic relaxation and a lower crustal viscosity of η*lc* = 1+0.8 −0.4 × 10<sup>19</sup> Pas. The viscosity of the uppermost mantle is not constrained by the data, except that it is larger than 0.6 × 10<sup>19</sup> Pas. The relatively high lower crustal and uppermost mantle viscosities are consistent with a cold and dry lithosphere of the Zagros region.

**Keywords:** post-seismic deformation mechanism; InSAR time series algorithm; Kermanshah earthquake; viscoelastic relaxation
