On the Relationship Between Subduction Interface Roughness and Megathrust Earthquakes

Abstract

The interface between the downgoing- and overriding plates in subduction zones can host very large earthquakes, depending on the characteristics of the subduction zone. One parameter that is thought to play a role in tuning this seismogenic behavior is the subduction interface roughness. The size and distribution of bathymetric features on the interface, the amount of sediments that subduct, and processes that occur during subduction all contribute to this roughness. Many studies that addressed the relationship between the roughness and seismicity of the megathrust generally converge towards a model where a smooth interface is more prone to host large- to giant events, while a rough seafloor might hinder the occurrence of earthquakes. However, contradicting examples from nature exist as well, and a detailed understanding of this relationship is still missing. This review article discusses the most important studies, first providing an overview of studies that focus on the role of specific features on the seafloor, after which several global, more general approaches will be discussed. Finally, three well-studied regions are discussed in more detail, showing the complexity of the problem, but also the large trench-parallel variability in seismogenic behavior that can occur within a single subduction zone.