Hikurangi megathrust slip behavior influenced by lateral variability in sediment subduction

Abstract Subduction megathrusts exhibit a range of slip behaviors spanning from large earthquakes to aseismic creep, yet what controls spatial variations in the dominant mechanism remains unresolved. We present multichannel seismic images that reveal correlation between lithologic homogeneity megathrust and its behavior at subduction zone is world renowned for lateral transition, Hikurangi margin. Where exhibits shallow slow-slip central margin, protolith changes ~10 km downdip deformation front, transitioning pelagic carbonates compositionally heterogeneous volcaniclastics. At locked southern segment, forms consistently within above thickened nonvolcanic siliciclastic sediments (unit MES), which subduct beyond 75 horizontally. The presence MES layer plays key role smoothing over rough volcanic topography establishing uniform distribution lithologies frictional properties may enable earthquake ruptures.