Tectonic setting of a Megathrust

a, Topographic shaded relief map of the Costa Rica margin (from Global Multi-Resolution Topography (GMRT) synthesis within GeoMapApp⁴⁵). The Middle American Trench (MAT) is shown with a black line and black triangles on the upper plate. The 2011 coverage of the 3D seismic reflection volume (CRISP) is shown with a white rectangle. b, Inline 2150 from the CRISP volume showing the trench, frontal prism (green) and outer wedge with interpreted sections of slope sediments (yellow) and margin wedge (blue). c, Perspective view of the shallow megathrust looking seaward towards the trench and the frontal prism has been cut away. Inline 2640 (frontal prism) is shown for reference. The colour scales in a and c indicate depth below seafloor and grey denotes the seafloor. VE, vertical exaggeration; PFZ, Panama fracture zone; SZ, seamounts zone.