Evidence for deeply-subducted lower-plate seamounts at the Hikurangi subduction margin: implications for seismic and aseismic behavior

Abstract

Seamounts are prominent seafloor features found globally at convergent margins, where their eventual subduction has been observed to have significant effect on upper plate morphology, and is predicted to influence megathrust slip behavior. While shallow subduction of partially buried seamounts has been inferred to play a role in tectonic erosion and deformation of the upper plate (e.g., Dominguez et al., 1998;Von Huene & Scholl, 1991), less is known about what happens as a seamount subducts further because of the limited resolution of geophysical methods commonly used to identify subducting seamounts. Previous studies have imaged buried seamounts at shallow stages of subduction (e.g.,

Spatial Variation of Shallow Stress Orientation Along the Hikurangi Subduction Margin: Insights From In‐Situ Borehole Image Logging

“…Basement topographic variation, such as uplifted basement blocks or seamounts, can introduce gravity and density changes within the crust creating geomechanical inhomogeneities (e.g., Bassett et al., 2022; Chow et al., 2022). Such geomechanical inhomogeneities can add horizontal compressional stress around the uplifted basement margins and extensional stress above them, changing the stress orientations (Artyushkov, 1973; Bott, 1991; Enever et al., 1999; Gale et al., 1984; Rajabi et al., 2016a; Ruh et al., 2016; Sun et al., 2020).…”