Fig. 1: Overview map of the erosional margin of Northern Chile in the region affected by the 2014 Iquique earthquake.

The hypocenter (star) and slip contour lines (in meters) of the 2014 Iquique Mw 8.1 mainshock (red) and Mw 7.7 aftershock (blue) are from ref. ⁵⁸. Black lines indicate the locations of the seismic lines used in this study with yellow regions indicating a coherent plate boundary reflection. The location of MC23²² has been added in the overview map, where the same color is used for the plate boundary reflectivity. The white dashed lines show the depth of the plate interface estimated from the seismic reflection data. The colored circles according to the color bar are aftershocks (December 2014 until October 2016) from the 2014 Iquique earthquake recorded by ocean bottom seismometers indicated as green and orange triangles²². Seafloor bathymetry from ref. ²⁸ combined with GEBCO_2019 bathymetry (www.gebco.net), SRTM topography from ref. ⁵⁹. The convergence of the Nazca and South America plate indicated by a black arrow⁶⁰. The location of the seismic line defining the structure of the incoming plate⁴⁰ is shown by a red dashed line.