Subduction zone geodynamics and earthquake processes

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This proposal seeks limited funds to provide partial support for two to three graduate students at any given year over the next five years as part of my research program. The proposed research is designed to understand the works of subduction zones, for which the Cascadia subduction zone off Canada’s west coast is a near-home example. The students will study what enables megathrust faults to generate large earthquakes and what makes them creep in slow slip events, how stress is built up and relieved in earthquake cycles to affect the geology of the upper plate, whether and why seismic activities in areas very far apart are physically connected, and so forth. The proposed research addresses fundamental geodynamics, and it helps society to understand what causes seismic and tsunami hazards. Our main method is to use computer modelling to explain global multidisciplinary observations to reveal underlying physical principles. The students are directed to develop geodynamic concepts from large volumes of observations and basic principles, not merely from textbooks and conventional models. With the long-term goal of understanding the geodynamics of subduction margins, especially processes that govern earthquake generation, we will proceed in three interrelated research directions over the next five years. The first direction is to explore the link between earthquake cycle deformation and geological deformation. We need to examine subduction margins around the world and develop models with realistic, although complex, mechanical properties to investigate stress and structural evolution over individual and multiple earthquake cycles. The second direction is to study whether the decoupling of the shallow and harder part the Earth (the lithosphere) and the deeper and softer part (the asthenosphere) can explain seemingly mysterious long-range interactions of regions very far apart, either in the same subduction zone or in different subduction zones. The third direction is to address how temperature and fluids control the slip behaviour of subduction faults, in particular to develop a unified model to explain geophysical conditions for slow slip events and the relation of these events with the part of the fault that generates great earthquakes.