Strain partitioning estimation in the eastern part of the tibetan plateau from block models constrained by GPS measurements and automated FLATSIM time series analysis of Sentinel-1 InSAR data

International audienceThe use of high spatial and temporal resolution data is a key condition for characterizinginterseismic deformation along major faults and understanding their roles in accommodatingthe deformation. Here we present an analysis using 4 years of Sentinel-1 InSAR data tocharacterize interseismic deformation along the Xianshuihe (XSH) fault system and theKunlun (KUN) fault in the eastern edge of the Tibetan plateau.Thanks to the NSBAS automated processing chain (Doin et al., 2011, Grandin, 2015),implemented at the CNES high-performance computing center in Toulouse as part of theFLATSIM project (ForM@Ter LArge-scale multi-Temporal Sentinel-1 Interferometryprocessing chain in Muscate), we automatically perform high-resolution time series analysisof 2014-2019 Sentinel-1 InSAR data set, acquired along 1200 km-long ascending anddescending orbits, over the study area. According to an elastic block model approach, InSARtimes series are combined to the latest published GPS velocity field and inverted using theblock modeling software TDEFNODE (McCaffrey., 2009) to model fault slip rates andcoupling distribution along these two major strike-slip faults and identify asperities andpotential creeping areas as well as analyze internal block deformation.Our models suggest the existence of a fault connecting the XSH fault and the KUN fault andaccomodating part of the deformation at a constant slip rate of 10 mm/yr. It shows that theslip rate on the XSH fault system increases from west to east, from 5 mm/yr to 14 mm/yrbetween latitudes 34.3°N and 29.3°N, while the slip rate on the Kunlun fault slightlydecreases from west to east from 10 mm/yr to 9 mm/yr. The slip deficit rate observed alongthe XSH fault system shows strong lateral variations, that we analyze with respect to theseismic history of the fault, and suggests the presence of shallow creep on the eastern part ofthe fault. The slip deficit rate observed along the Kunlun fault appears more homogeneous.However, we observe a strong deformation gradient that we interpret as a post-seismic signalat the eastern tip of the rupture of the 2001 Kokoxili earthquake and we analyze its temporalevolution