Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

At present, scientists are not able to predict earthquakes, in part because we do not have a fundamental understanding of the earth processes which control when and where earthquakes occur and how big they are. Seismic waves shake the earth's surface and are detected by seismometers, which allow scientists to pinpoint the exact time and location of the fault rupture which caused the earthquake at depth within fault zones. I investigate the controls on earthquakes by identifying this earthquake source region in ancient fault zones which have been uplifted and exposed by erosion at the surface of the earth. Studying the earthquake source in situ within the rocks allows me to make observations on small scales (kilometers down to nanometers), which are the scales at which individual mineral grains break, melt, and react to control the rock properties during earthquakes, but which are beyond the limit of modern seismology. My approach involves significant time invested in exploration and discovery of new field areas where ancient faults are exposed, with the intention of opening up the breadth of variation across many types of fault systems to contribute to a more generalized understanding of earthquakes. The ancient faults allow me to study the geometry of slip surfaces and infer controls on the energy balance at depth during the seismic cycle. Using cutting-edge field techniques including drone aerial photography, I reconstruct a three-dimensional model of outcrops of ancient fault zones and use these to compare the fundamental geometry and length scales of ancient earthquake ruptures to the modern earthquake observations from seismology and geodesy. I identify the rock chemistry, mineralogy, and fluid-rock reactions which characterize these faults before, during and after earthquakes. Fluid-rock reactions in seismic faults are of particular importance to Quebec and Canada because these fluids are responsible for the deposition of some types of ore deposits, and earthquakes are events which can trigger the deposition of precious metals. By investigating a range of ancient fault sites in different rock types and tectonic settings, my research contributes to a general model for controls on the earthquake cycle across Canada and the rest of the world.