Collaborative Research: Controls on along-strike variations in locked and creeping megathrust behavior at the Hikurangi convergent margin


Investigators: The SHIRE team (Marshall, McIntosh, Okaya, Pilarczyk, Saffer, Van Avendonk, Wallace), GNS Science (Cochran, Clark, Litchfield)
Graduate students: Rachel Stearns, Stephen Mitchell


National Science Foundation (NSF) Integrated Earth Systems (IES) EAR-1616847

Project Summary

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.

Key outcomes

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



"Using microfossils to understand earthquakes could be ground-breaking". Jessica Pilarczyk, Thomas Kosciuch, and Stephen Mitchell’s work on Hikurangi trench paleoseismology is featured by Research Features

A “Window into pre-history”. Jessica Pilarczyk, Thomas Kosciuch, and Stephen Mitchell’s work on Hikurangi trench paleoseismology is featured by The Wairoa Star

“Tsunami hunt in Wairoa Lagoon”. Jessica Pilarczyk, Thomas Kosciuch, and Stephen Mitchell’s work on paleotsunamis in New Zealand is featured by Gisborne Herald

Supplementary Data

Coastal Hazards Research Lab
Division of Marine Science
School of Ocean Science and Technology
University of Southern Mississippi
1020 Balch Blvd., Stennis Space Center, MS 39529