Rethinking Megathrust Segmentation: New Strategies to Link Sedimentary Paleoshaking Evidence to Rupture Parameters

Paleoseismic research is a key concept in seismic hazard assessment, allowing earthquakes to be revealed that were potentially larger than the highest-magnitude earthquakes known from historical records. Defining the recurrence mode (timing and location) of large, destructive earthquakes is crucial to prepare society for a potentially imminent earthquake and mitigate the risks associated with it. The wealth of paleoseismic research that exists along subduction zones around the world resulted in qualitative estimates of their recurrence rate, although quantitative estimations of the spatial extent of past megathrust earthquakes are currently lacking. This is because it is unclear how the spatial distribution of paleoseismic evidence relates to the rupture extent and slip of the causative earthquake. In this project, we aim to develop a new methodology that allows revealing the rupture characteristics of megathrust earthquakes by combining sedimentary paleo-earthquake evidence with ground-motion modelling. With this quantitative approach, we can confidently identify the rupture extent and location of past megathrust earthquakes in subduction settings around the world and re-evalute the currently existing concepts of megathrust segmentation and earthquake supercycles. This is a major step towards adequate seismic hazard assessments, pushing the frontiers of subduction zone paleoseismology.