Dr. Christie Rowe (Geotop-McGill)
Gill Room, FDA 232, 3450 rue Université, Université McGill
Résumé / Abstract:
Subduction zone fault systems produce a wide range of fascinating and societally important phenomena, including great earthquakes and tsunamis, silent earthquakes, tremor, and slow slip. Development in geophysical and geodetic capabilities and coverage over the last few decades has driven rapid advancements in our ability to detect these events and also our appreciation for the complexity and diversity of subduction zone fault systems. Fault strength, slip, creep, and healing are controlled by grain-scale deformation mechanisms and material and hydrological properties, which are difficult or impossible to measure in situ. Over geologic time, rocks accumulate deformation and record the cycling in permeability and fluid flow, loading and relaxation, and long-term accumulation of plastic strain that control the earthquake cycle. Geological field studies of exhumed faults are therefore our best tool for observing the key processes at the scales they are active, and developing a deeper mechanistic understanding of the processes that control the dynamics of subduction zones.
In this talk I will explain how subduction thrust faults are preserved in the rock record and how we determine the ancient tectonic context. I will show how my research group has used geological field observations to elucidate fundamental processes controlling the rates of seismic slip, post-seismic strengthening and strain partitioning which control the earthquake cycle, and describe current projects which seek to understand plate interface stresses in the tremor source region. Finally, I will argue that with the recent advances in subduction science, the time is ripe for field geologists to make major breakthroughs to advance our understanding of subduction dynamics and earthquake mechanics.
Geological controls on subduction thrust fault behavior