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).