Infrastructure stability diagnosis via postseismic deformation: A case study of 2016 Meinong earthquake in southwestern Taiwan using multitemporal Sentinel-1 satellite

Compared with obvious records of coseismic surface ruptures and displacements, the postseismic surface deformation is often to be omitted. On the other hand, the deformation rate of the postseismic deformation is much faster than of the interseismic surface deformation. Therefore, how to efficiently assess the hazard potential of the infrastructures induced by postseismic displacements is of practical to the societal security. In this study, we processed multi-temporal images taken by Sentinel-1 satellite via using the persistent scatterer InSAR (PSI) technique. With the constraints of continuous GNSS data, we estimated 2D (E-W and vertical) postseismic deformation rates for 3 years after the 2016 Meinong earthquake. An annual deformation tolerance ratio (ADTR), converted by the 2D displacement rates based on the maximum deformation tolerance of public infrastructure , was proposed for the assessment on public transportation systems, to highlight the segment with high hazard potential. We picked up each pixel on the high-hazard potential segments of high-speed railway (HSR) with time-series variation analysis to characterize spatiotemporal behaviors of the fault systems after the seismic event. The 2D postseismc deformation rate in E-W direction and vertical direction are 1.5 and 2-3 times respectively higher than of the interseismic duration, respectively. The ADTR results indicated that the high-hazard potential segment of HSR in the vertical direction was located on Tainan City with 22–33‰, and that in the E-W direction was located on Kaohsiung City with 5–7.5‰. The time-series variation results presented that the hazard potential gradually decreased after mid-2017. Our observations combined the geological settings and the environmental conditions that can effectively assess the degrees of hazard potential of infrastructures during the postseismic period. The postsesimic deformation should be included into the seismic hazard assessment of urban area where high seismic risk exists, and the results of ADTR and time-series variation could be considered into the seismic hazard assessment in the engineering scale for the public transportation system.