Subducting seamounts control interplate coupling and seismic rupture in the 2014 Iquique earthquake area

To date, the parameters that determine the rupture area of great subduction zone earthquakes remain contentious. On 1 April 2014, the Mw 8.1 Iquique earthquake ruptured a portion of the well-recognized northern Chile seismic gap but left large highly coupled areas un-ruptured. Marine seismic reflection and swath bathymetric data indicate that structural variations in the subducting Nazca Plate control regional-scale plate-coupling variations, and the limited extent of the 2014 earthquake. Several under-thrusting seamounts correlate to the southward and up-dip arrest of seismic rupture during the 2014 Iquique earthquake, thus supporting a causal link. By fracturing of the overriding plate, the subducting seamounts are likely further responsible for reduced plate-coupling in the shallow subduction zone and in a lowly coupled region around 20.5ºS. Our data support that structural variations in the lower plate influence coupling and seismic rupture offshore Northern Chile, whereas the structure of the upper plate plays a minor roleJ.G. was funded by a grant (CP1404) of the Cluster of Excellence 80 ‘The Future Ocean’. The Future Ocean is funded within the framework of the Excellence Initiative by the Deutsche Forschungsgemeinschaft on behalf of the German federal and state governments. R/V Sonne Cruise SO104 was carried out with Grant No. 03G104A by the Bundesministerium für Bildung und Forschung. [...] C.R.R. was supported by the Grup de Recerca 2014SGR940 de la Generalitat de CatalunyaPeer Reviewe