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The great 2012 Mw 8.6 strike‐slip earthquake beneath the Wharton Basin generated a complex aftershock sequence that maps onto a system of conjugate faults. Analysis of high‐precision aftershock locations with improved depth constraint is used here to characterize the seismogenic limits of the oceanic lithosphere. The study presents teleseismic double‐difference earthquake relocation results for 695 events in and around the 2012 Wharton Basin intraplate earthquake sequence. We highlight seven major clusters of seismicity and show that the 2012 earthquake sequence ruptured in the oceanic crust and upper mantle. The refined aftershock locations projected onto available mainshock finite‐fault models show that aftershocks occur outside the largest coseismic slip region and tend to cluster in low slip areas, a pattern commonly seen for large continental and megathrust sequences. For events with depth phases, the relocated focal depths generally correspond to predicted depths from pP‐P time observations. Reported pP‐P observations for intraplate events correspond to depths ranging from ~5 to 35–40 km, such that the deepest events occur within the expected limit of brittle seismic failure at 600 °C, here defined by a half‐space cooling model of the region. The 74 low magnitude events in our catalog that locate below the 600 °C isotherm do not have consistent depth phase observations and cannot be interpreted as strong evidence of rupture into the ductile regime. The refined double‐difference catalog supports that, along with deep coseismic rupture, moderate‐sized earthquakes ruptured across the full extent of the elastic oceanic lithosphere in the Wharton Basin. Key Points: Aftershocks are consistently located away from significant coseismic slip across multiple faultsAftershock depth distribution shows full rupture of the elastic lithosphere in agreement with coseismic slip modelsThe 600 °C isotherm provides a robust limit on the depth extent of fault slip in the Wharton Basin [ABSTRACT FROM AUTHOR]

The terminal stage of subduction sets in when the continental margin arrives at the trench and the opposite forces of the sinking slab and buoyant continent extend and ultimately sever the subducted lithosphere. This process, although common in geological history, is short-lived, and therefore rarely observed. The deep seismicity under the Hindu Kush (Central Asia), including the 2015 M w 7.5 event, is a rare case that testifies to this process. Here, we use new seismological data to create a high resolution picture of slab break-off and infer its dynamics. High precision earthquake locations and tomographic images show subduction of continental crust down to ∼180 km. A large dataset of source mechanisms indicates sub-vertical extension in the entire slab but a strain rate analysis showed that the deeper seismogenic portion of the slab, below the subducted crust, extends at higher rates (∼40 km/Ma). Most M w > 7 earthquakes between 1983–2015, relocated relative to our new well-constrained earthquake catalog, cluster in a small volume below 180 km, and indicate shearing on an overturned interface. A slip model for the latest 2015 M w 7.5 event suggests that it ruptured into a seismic gap on this interface. From this configuration we conclude that a horizontal slab tear develops along-strike of the Hindu Kush seismic zone at the base of the subducted continental crust. Below the subducted crust, the deepest and also largest earthquakes (180–265 km) are likely associated with deformation in the mantle lithosphere. From the seismicity distribution and the rupture mechanisms we further deduce that the dominant deformation mechanism in this deeper portion of the slab changes along-strike from simple to pure shear. The fastest detachment rates and largest earthquakes occur during the simple shear dominated stage. Earthquakes in the upper part (60–180 km), above the rapidly extending slab, might be triggered by processes related to the subduction of crustal rocks. [ABSTRACT FROM AUTHOR]