Recurring large deep earthquakes in Hindu Kush driven by a sinking slab

Hindu Kush subduction zone produces large intermediate-depth earthquakes within a small volume every 10–15 years. Here we study the last three M ≥ 7 events within the cluster and find complex and diverse rupture processes. However, their main subevents appear to recur on the same fault patch, dipping 70° to the south. This recurrence requires an average of 9.6 cm/yr slip rate on the patch, much higher than the ~1 cm/yr surface convergence rate measured geodetically. The high slip rate is likely caused by significant slab internal deformation, such as localized slab stretching/necking. We infer that the Hindu Kush subducted slab below 210 km is sinking through the mantle at a vertical rate of 10 cm/yr.