Subduction zones produce the largest and most destructive earthquakes and tsunamis. Knowledge of the mechanics governing fault slip behavior along the subduction thrust interface is necessary to understand and mitigate the hazards posed by these major plate boundary features. Many recent devastating subduction earthquakes have highlighted our lack of understanding of the nucleation and propagation of unstable slip at convergent plate boundaries. It is now widely acknowledged that transient slow slip events (SSEs) can also accommodate a significant portion of the plate convergence in subduction zones. Despite the fact that there is widespread evidence for episodic slow slip behavior that bridges the gap between the stick-slip and stable sliding end-members, the physical mechanisms leading to SSEs, and their potential relationship to large, damaging and tsunamigenic earthquakes, are unknown at present. The SHIRE team (Seismogenesis at Hikurangi Integrated Research Experiment) aims to address these gaps in understanding through an integrated, system-level approach that combines large-scale seismic imaging, and paleoseismology and geomorphology, focused through the lens of numerical modeling To investigate along-strike variations in megathrust locking and slip through multiple seismic cycles, members of the Coastal Hazards Research Lab at The University of Southern Mississippi will examine geologic and geomorphic indicators of upper plate deformation using paleoseismology, recording discrete seismic cycle uplift and subsidence events through the Holocene (~0.1-10 ky). One of the principal aims of the paleoseismological component of the study is to determine if modern instrumentally observed patterns of megathrust locking and slip are long-lived through multiple seismic cycles, or rather are instead transient phenomena that change over time. These results will also better constrain the past seismic behavior of the megathrust that is needed to evaluate the physical controls on megathrust behavior from the numerical modeling and seismic imaging portions of the project.

This is a project in its first year. Stay tuned...