Stopping phase reveals abrupt arrest of large strike-slip earthquakes

Earthquake magnitude is controlled by where and when rupture propagation stops. However, rupture arrest has rarely been directly observed in near-field seismic records of natural earthquakes. Here, we present systematic near-field observations of ground-motion stopping phases from large strike-slip earthquakes. Analysis of 12 global events shows that transient overshoot in fault-parallel ground surface displacement is a robust diagnostic signature of abrupt termination of rupture propagation. Dynamic rupture simulations reveal that near-field ground motions are strongly amplified by low-wavespeed rocks at shallow depth, which enhances the amplitude of displacement overshoot recorded at the surface. The occurrence of stopping phases at near-fault locations far from mapped rupture termini implies that large strike-slip earthquakes rupture in a segmented manner, with dynamic rupture propagation punctuated by abrupt arrest and reinitiation at internal fault-segment boundaries.