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 l c = 1 − 0.4 + 0.8 × 10 19 Pas . The viscosity of the uppermost mantle is not constrained by the data, except that it is larger than 0.6 × 10 19 Pas . The relatively high lower crustal and uppermost mantle viscosities are consistent with a cold and dry lithosphere of the Zagros region.
Highlights
The Mw 7.3 Kermanshah earthquake of 12 November 2017 near the Iran/Iraq boundary occurred along a thrust fault of the Zagros Mountains
Post-seismic displacements can be caused by (i) afterslip along the fault, either along the patch that ruptured during the earthquake or next to it [4,5,6,7]; (ii) viscoelastic relaxation of the lower crust and/or upper mantle [8,9,10]; (iii) poroelastic rebound following earthquake-induced pore-fluid pressure changes [11,12,13]; or (iv) large aftershocks
We came to the following conclusions: For the first six months the post-seismic displacement was due to the afterslip along the up-dip extension of the rupture zone
Summary
The Mw 7.3 Kermanshah earthquake of 12 November 2017 near the Iran/Iraq boundary occurred along a thrust fault of the Zagros Mountains. Post-seismic displacements can be caused by (i) afterslip along the fault, either along the patch that ruptured during the earthquake or next to it [4,5,6,7]; (ii) viscoelastic relaxation of the lower crust and/or upper mantle [8,9,10]; (iii) poroelastic rebound following earthquake-induced pore-fluid pressure changes [11,12,13]; or (iv) large aftershocks. These processes have different spatial-temporal characteristics [14]. A earthquake information came from USGS earthquake catalog: https://earthquake.usgs.gov/earthquakes/
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