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Faulting and Earthquake Cycles

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 focus of the FEC group is to design integrated SZ4D experiments and efforts to address the questions of when and where earthquakes happen in subduction zones.

Overarching question

Which subduction zone segments are more likely to produce big earthquakes and what properties govern that likelihood?


  1. 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?

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

  3. Does distinctive precursory slip or distinctive foreshocks exist before earthquakes? What causes either foreshocks or precursory slip?

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

Working Group Members

Jonathan Ajo-Franklin (Rice University)

Scott Bennett (USGS)

Roland Burgmann (Berkeley)

Wenyuan Fan (UC San Diego)

Shuoshuo Han (UT Institute for Geophysics)

Yihe Huang (University of Michigan)

Hiroko Kitajima (Texas A&M University)

Jeff McGuire (USGS)

Samer Naif (Georgia Tech)

Emily Roland (Western Washington University)

Sergio Ruiz (Universidad de Chile)

* Demian Saffer (UT Institute for Geophysics)

Heather Savage (UC Santa Cruz)

Ignacio Sepúlveda (San Diego State University)

* Donna Shillington (Northern Arizona University) - co-Chair

Tianhaozhe Sun (Geological Survey of Canada)

Laura Wallace (UT Institute for Geophysics)

Shawn Wei (Michigan State University)

* Steering Committee Member

Planning for the SZ4D Initiative: Meet the Faulting & Earthquake Cycles Working Group (June 2020 SZ4D Webinar)

Group Contacts

Donna Shillington - Donna.Shillington (at)
Demian Saffer - demian (at)

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