Large Surface‐Rupture Gaps and Low Surface Fault Slip of the 2021 Mw 7.4 Maduo Earthquake Along a Low‐Activity Strike‐Slip Fault, Tibetan Plateau.

Based on field investigations, interpretations of high‐resolution UAV images, and analyses of available InSAR data, we mapped the fault geometry and surface ruptures of the 2021 Mw 7.4 Maduo earthquake that occurred on a low‐activity strike‐slip fault within the Tibetan Plateau. The results indicate that (a) the earthquake activated a fault that is ∼161 km long and has complicated structural geometry; (b) the surface rupture occurs over a distance of 148 km, but is separated into three distinct segments by two large gaps (38 and 20 km, respectively); (c) within the surface‐rupture segments, the horizontal and vertical displacements are typically 0.2–2.6 m (much lower than the InSAR‐based slip maximum of 2–6 m at depth) and ≤0.4 m, respectively. The two large gaps of the Maduo surface rupture represent the two largest surface‐rupture discontinuities of strike‐slip earthquakes ever documented, and coincide with structurally complicated fault portions and near‐surface soft sediments. Plain Language Summary: Evaluating the seismic potential of low‐activity strike‐slip faults is commonly challenging because of (a) the difficulty in mapping of causative fault geometry that has subtle topographic expression, and (b) limited fault slip at the surface (relative to that at depth) produced by each earthquake. Our investigation of the 2021 Maduo earthquake demonstrates that, along the low‐activity strike‐slip fault, laterally significant gaps (up to 40 km wide) may separate extensive co‐seismically ruptured regions on either end of such gaps, which can thereby compromise typical methodologies used to assess paleoseismic ruptures and may lead to underestimates of seismic hazard. This observation increases the challenge of assessing the seismic potential of low‐activity strike‐slip faults. Key Points: The Maduo earthquake activated a 161‐km‐long strike‐slip fault with subtle topographic expression and complicated structural geometryThe surface rupture occurs over a distance of 148 km, but includes two large gaps that are 38 and 20 km, respectivelyWithin the surface‐rupture segments, the horizontal slip is 0.2–2.6 m, much lower than the InSAR‐based slip maximum of 2–6 m [ABSTRACT FROM AUTHOR]