| Summary: | On 23 June 2014, a large (M_W 7.9) earthquake ruptured within the subducting Pacific plate ~100 km below the Rat Islands archipelago, Alaska. The focal mechanism indicates two possible rupture orientations: on a shallowly dipping fault plane striking perpendicular to the trench, possibly related to curvature of the underthrust slab or; on a steeply dipping fault plane striking parallel to the trench, possibly associated with a slab detachment process. Joint inversion of teleseismic body waves and regional highâ€rate (1Hz) GPS recordings indicate a slip zone spanning 50 km × 30 km with a maximum slip of ~11 m on the shallowly dipping plane, or a more distributed slip pattern extending upward to ~70 km, with maximum slip of ~14 m on the steeply dipping plane. The finiteâ€fault models and aftershocks do not indicate a preferred fault plane. This type of intermediateâ€depth intraslab faulting can be very damaging for populated regions above subduction zones such as Japan, Taiwan, Chile, Peru, and Indonesia. © 2016 American Geophysical Union. Published Online: 18 October 2016; Published Print: 09 August 2016. The IRIS DMS data center (http://www.iris.edu/hq/) was used to access the seismic data from Global Seismic Network and Federation of Digital Seismic Network stations. This work made use of GMT and SAC software. This work was supported by NSF grant EAR1245717 (T.L.).
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