Role of Active Folding in Rupture Arrest of a Great Thrust Earthquake

Understanding the cause and location of the end-points of thrust earthquake ruptures is critical yet unresolved question in seismic hazard assessment for convergent margins, where numerous destructive earthquakes have occurred. Here, we offer a novel perspective on rupture termination by examining the arrest of the 1906 M 8.0 Manas earthquake in northwestern China. Integrated field surveys, seismic profiles, and microseismicity data reveal that rupture terminated at the actively growing Xiaodushan anticline. This anticline lies parallel to and in the hanging wall of the seismogenic fault. We propose active folding acts as an efficient rupture-arrest barrier, partitioning seismic energy into strata uplift and microseismicity. Furthermore, comparative analysis of global thrust earthquakes identifies two termination mechanisms: fault geometric complexities and external structural barriers. These findings contribute to deeper understanding of rupture lengths and earthquake magnitudes for seismic hazard assessment in convergent margins globally.