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When and where do large earthquakes happen?

How do faults work – at all levels of the subduction system?

Anticipating the timing of major earthquakes and which fault segments present the greatest hazard has long been a challenge in subduction zone science. At the largest spatial scale, deformation throughout the subduction system is coupled in space and time, and novel geodetic and seismologic observations made possible by the emergence of offshore instrumentation is poised to help us unravel these connections. At the smallest spatial scale, deformation processes control how rocks respond to the boundary conditions, whether by faulting or distributed flow, and how faults slip, whether by seismogenic slip, aseismic creep, or intermediate behaviors.


Understanding these processes requires new laboratory experiments designed to determine the properties of complex rocks that experience complex histories and investigations of rocks exhumed from fossil systems to ground-truth these measurements and observations. Finally, relating the processes by which rocks deform locally to the spatial and temporal evolution of the system requires numerical models validated by structural images from active source seismic, MT, bathymetric data, and modern surface techniques (LiDAR, paleoseismology).

The SZ4D Faulting and Earthquakes Cycles Working Group focuses their effort around four central questions that define the limits of what we know about when, where, and why large earthquakes occur.

FEC Overarching Question

When and where do large earthquakes happen?

FEC Science Questions

A major goal of earthquake studies is to be able to predict relationships between geographic location and earthquake and tsunami hazards. Prediction of specific earthquakes may be impossible, but physical models of fault failure are capable of predicting important features of the earthquake cycle when developed in collaboration with observational and experimental studies. We break up this major question into four sub-questions that focus on different aspects of the subduction zone earthquake problem, each of which has societal importance. Addressing these four questions by integrating observational, laboratory, and modeling efforts will allow us to make progress on the grand challenge of earthquake predictability.

FEC Science Questions

  • How do subduction zone fault systems interact in space and time? How do these fault systems and associated deformation regulate subduction zone evolution and structure?

  • What controls the speed and mode of slip in space and time?

  • Do distinctive precursory slip or distinctive foreshocks occur before earthquakes? What causes either foreshocks or precursory slip?

  • Under what physical conditions and by what processes will slip during an earthquake displace the seafloor and increase the likelihood of generating a significant tsunami?

From the Implementation Plan

Download the FEC section of the SZ4D Implementation Plan

From the Implementation Plan

Group Members

Lingling Ye
SUSTech China
Belle Philibosian
Julie Elliott
Michigan State University
Cailey Condit
University of Washington
Emily Roland
Western Washington University
Sergio Ruiz
Universidad de Chile
Demian Saffer*
Heather Savage
UC Santa Cruz
Ignacio Sepúlveda
San Diego State University
Donna Shillington*
Northern Arizona University
Tianhaozhe Sun
Geological Survey of Canada
Laura Wallace
University of Texaas
Shawn Wei
Michigan State University
Hiroko Kitajima
Yihe Huang
University of Michigan
Shuoshuo Han
Wenyuan Fan*
UC San Diego
Scott Bennett
US Geological Survey
Jonathan Ajo-Franklin
Rice University

*Group Co-Chairs

FEC Group Members

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