Off-fault damage controls near-surface rupture behaviour in soft sediments

Surface-rupturing faults represent some of the most devastating examples of earthquake-related hazards. Near surface rupture behaviour is poorly understood, due to limited information concerning the amount of off-fault energy dissipated in a volume surrounding the propagating rupture tip. Here, we show that the energy dissipated by off-fault damage in shallow seismic faults can slow down and arrest ruptures in the near surface regions. We integrate experimental results with field measurements from near-surface seismic faults in the Dead Sea, to estimate that off-fault damage is up to 85% of the total fracture energy dissipated during a M_w ≈ 6 rupture events. Analytical modeling of the studied faults demonstrates that increased fracture energy from off-fault damage energy dissipation significantly slows or halts rupture propagation near the surface. Here, we plausibly explain the slow rupture velocities and low radiation efficiencies observed in shallow ruptures in soft sediments.