Geodetic observations
We process Sentinal-1 and Advanced Land Observation Satellite-2 (ALOS-2) SAR data (Table S1) to derive 11 surface deformation images through DInSAR (differential interferometric SAR)[Gabriel et al. , 1989], POT (pixel offset tracking)[Michel et al. , 1999], MAI (multiple aperture interferometry)[Bechor and Zebker , 2006], and/or BOI (burst overlap interferometry)[Grandin et al. , 2016] methods (Fig.S1). These images provide high-quality and comprehensive spatial coverage of the surface deformation produced by the earthquake. We then use them to calculate the 3D co-seismic displacement with the Strain Model and Variance Component Estimation method[J Liu et al. , 2019b; J-H Liu et al. , 2017] (Supplement text-1 ). The high-resolution 3D surface deformation shows sharp offsets across the fault, thus the surface rupture, continuously along the near E-W oriented Jiangcuo fault (Fig.1b and Fig.S2), which agrees well with the surface rupture mapping from field surveys [Ren et al. , 2022]. The total surface rupture length is ~160 km, ~60 km longer than that predicted from empirical relationships [Leonard , 2010;Wells and Coppersmith , 1994], suggesting a relatively shallow rupture of the earthquake. The coseismic deformation is dominated by left-lateral strike-slip motion (Fig.1a), and shows at least five primary step-overs or fault bends (strike change > 10°) and one fault bifurcation. The refined hypocenter of the mainshock [W Wang et al. , 2021] is located in the middle of the surface rupture trace very close to one of the primary fault step-overs, where stress concentrations usually nucleate an earthquake rupture [King and Nábělek , 1985]. Interestingly, the epicenter is co-located with the intersection between the Yellow River and the ruptured JiangCuo fault (Fig.2a), although their relationship is not yet clearly understood. Larger surface deformation is observed to the east of the epicenter, and therefore a stronger rupture directivity effect is expected toward the east. Coseismic offsets are clearly observed across the bifurcated fault branches near its eastern terminal (Fig.1a).