The northern Hikurangi margin three-dimensional plate interface in New Zealand remains rough 100 km from the trench
In This work we mapped the Hikurangi margin plate interface using receiver functions from data collected by a dense 22 x 10 km array of 49 broadband seismometers. Our mapped plate interface has kilometer-amplitude roughness we interpret as oceanic volcanics or seamounts, and is 1–4 km shallower than the regional-scale plate-interface model used in geodetic inversions. We show interface roughness also leads to shear-strength variability, where slip may nucleate in locally weak areas and propagate across areas of low shear-strength gradient.