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Topic

Understanding Earthquake-Cycle Deformation Around Subduction Zones and Strike-slip Faults

School of Earth and Ocean Sciences

Date & location

• Monday, March 30, 2026
• 9:00 A.M.
• Clearihue Building, Room B017

Examining Committee

Supervisory Committee

• Dr. Edwin Nissen, School of Earth and Ocean Sciences, ̽��ϵ�� (Co-Supervisor)
• Dr. Kelin Wang, School of Earth and Ocean Sciences, UVic (Co-Supervisor)
• Dr. Stan Dosso, School of Earth and Ocean Sciences, UVic (Member)
• Dr. Tianhaozhe Sun, School of Earth and Ocean Sciences, UVic (Member)
• Dr. Henning Struchtrup, Department of Mechanical Engineering, UVic (Outside Member)

External Examiner

• Dr. Kaj Johnson, Department of Earth and Atmospheric Sciences, Indiana University

Chair of Oral Examination

• Dr. Anthony Quas, Department of Mathematics and Statistics, UVic

Abstract

This doctoral research investigates earthquake cycle deformation in subduction zones and strike-slip faults that is governed by the physical properties of the lithosphere and asthenosphere. Using numerical and semi-analytical modelling constrained by diverse observations, I analyze the three phases of the cycle: coseismic, postseismic, and interseismic, each being dominated by one aspect of the viscoelastic rheology.

Coseismic (elasticity): Accurate modelling of seafloor deformation is critical for tsunami hazard assessment at subduction margins. The elastic dislocation model with prescribed fault slip remains the preferred tool for this purpose owing to its distinct advantages, but at the cost of missing realistic surface geometry and heterogeneous rigidity. Through systematic comparison with finite element models that include these realistic features, we demonstrate that the absence of a sloping seafloor in dislocation models can be accurately compensated for by adjusting the fault depth to match the actual depth below the seafloor. We also show that the effect of heterogeneous rigidity on tsunamigenic uplift is negligible when fault slip is prescribed.

Postseismic (predominantly transient viscoelasticity): The far-field deformation following the 2012 Haida Gwaii and 2013 Craig earthquakes offers a unique window into the transient rheology of the upper mantle. Geodetic observations hundreds of kilometres away from the epicentres indicate postseismic motion that lasted only 2–3 years. We demonstrate that this short-lived deformation was driven entirely by the transient (Kelvin) rheology. These results reveal that the elastic lithosphere acted as a stress guide, transferring stress to the far field against the resistance of the asthenosphere undergoing transient creep.

Interseismic (predominantly steady-state viscoelasticity): The conventional elastic model for inferring locking depths of seismogenic faults from geodetic observations assumes time-invariant interseismic deformation, contradicting the actual time-dependent deformation in a viscoelastic Earth. We propose to replace the elastic model with a viscoelastic model while maintaining operational simplicity. Using the Altyn Tagh Fault in a case study, we show how to apply this to real faults and handle complications due to non-uniform rigidity, presence of fault creep, and postseismic transients of nearby earthquakes.