Rupture branching, propagation, and termination at the eastern end of the 2021 M_w 7.4 Maduo earthquake, northern Tibetan plateau

The propagation of the 2021 M_w7.4 Maduo earthquake rupture from the central Jiangcuo fault (JCF) onto its eastern terminus, in the northern Tibetan Plateau, exhibits a complex surface geometry with conjugate faults, bends, and stepovers. About 50 km east of the 2021 earthquake epicenter, which is located at Maduo County within the Tibetan plateau, the surface rupture along the Jiangcuo eastern fault (JCEF), deviating <20° anticlockwise from the general strike, provides a valuable chance for understanding rupture processes through a geometrically complex fault network where ≥4 interactional faults come together. Using orthophotos derived from an unmanned aerial vehicle (UAV) survey with a ground resolution of 6 cm, complemented by field investigations, we mapped the surface rupture in detail and measured the coseismic slip distribution of the JCEF. Our mapping illuminates sporadic breaks of tectonic origin in the sand dune area immediately near the branching point and a more simple, linear rupture trace eastward of the junction. The high-resolution slip measurements along the JCEF follow approximately a dogtail shape to the eastern termination with a maximum left-lateral coseismic slip of 2.9 m at a fault bend. We found linear surface ruptures along the NW-strike geologic faults, indicating triggered coseismic slip on conjugate faults. The intersections with conjugate faults overlap with discontinuities in rupture geometry and interference of surface slip on the main fault. We propose that triggered slip on pre-mapped Quaternary faults impacted the rupture propagation onto the JCEF. The complexity in rupture geometry suggests fault interaction in the eastern tip zone of the Maduo rupture.