Quantification and modelling of post-seismic deformation following the 24 September 2013 Mw 7.7 earthquake in the Makran region, Pakistan


 On 24 September 2013, an earthquake of magnitude Mw 7.7 occurred on the Hoshab fault in southern Pakistan, south of the 650-km-long Chaman Fault, within the eastern Makran accretionary wedge. This earthquake was caused predominantly by strike–slip faulting. To quantify the post-seismic deformation following this large earthquake, we used ascending and descending Sentinel-1 data over the period November 2014–December 2017. The deformation time series over these 3 years shows that the post-seismic deformation was not linear over the time. To determine the mechanisms that may have driven post-seismic deformation, such as after-slip or a combination of after-slip and viscous relaxation, we explored some models, including after-slip only, and a combination of after-slip and viscous relaxation, to identify the best fit between the observed and simulated deformation time series. Our results indicate that after-slip was the main mechanism controlling the post-seismic deformation. The introduction of a basal flat fault in the modelling improves the fit between the model results and the time series obtained from the satellite images This basal fault is located at a depth of 18 km, has a northward dip of 7°, and corresponds to the basal décollement level of the Makran accretionary prism.