[SCG58-07] Long-lasting afterslip associated with the 2016 moderate earthquakes along the Chaman fault, Pakistan
Keywords:Chaman fault, afterslip, Interferometric synthetic aperture radar, Sentinel-1
We focus on the two moderate earthquakes occurred on May 13 and July 10 in 2016 on the fault, which were the first M5-class events since the 2005 M5.0 event examined by Furuya and Satyabala (2008). Ascending 11 SAR data of C-band Sentinel-1 from 2015 to 2017 are used to generate 55 interferograms. To separate deformation signals from other temporally random errors, we perform InSAR time series analysis based on a linear least squares inversion, which translates the set of interferograms into a range change time series. We use Small Baseline Subset (SBAS) method, following Schmidt and Bürgmann (2003), to detect cumulative LOS displacements. Our results indicate long-lasting afterslip for both of the two events. In particular, the second event has a sharper phase discontinuity across the fault, whereas the LOS changes are smaller than the first event.
Based on the cumulative LOS changes derived by SBAS, we estimate fault source models in an elastic half-space. We use Triangular Dislocation Element (TDE) to build non-planar fault. Our model indicates cumulative slip distribution which expands(?)on the fault plane. The maximum slip for the first event increased from 0.12 m to 0.53 m at a depth of 4-5 km during the 293 days after the event, while that for the second event increased from 0.11 m to 0.26 m at a depth of 2 km during the 235 days after the event.