Illuminating northern Cascadia earthquake faulting using satellite and airborne geodesy

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Earthquake faulting helps shape our planet, controls the distribution of key natural resources, and impacts our climate. Earthquakes are also amongst the most significant global natural hazards, with millions of fatalities forecast this century and large parts of Canada at risk from damaging shaking and tsunami. Understanding what governs the location, size, and timing of earthquakes is therefore one of the grand challenges of geophysics. ******In moving to the University of Victoria in January 2017, I seek to tackle this challenge by building a new research group focused primarily on the tectonics of northern Cascadia. This Discovery Grant - together with a Canadian Foundation for Innovation proposal which supports related infrastructural needs - will fund two distinct projects, outlined below. Both elements exploit a new wave of satellite and airborne sensors which are revolutionizing our ability to map surface deformation and topography associated with earthquake faulting. Further motivation is provided by a recent global surge of megathrust earthquakes which have torn up the rule book on subduction zone behaviour.******Part A: Mapping Cascadia surface deformation with InSAR***We will use a new wave of Interferometric Synthetic Aperture Radar (InSAR) satellites to produce the first spatially-continuous surface deformation measurements that span the entire Cascadia fore-arc. InSAR can provide vastly-improved spatial coverage and enhanced sensitivity to vertical displacements compared to the sparse Global Positioning System (GPS) stations currently used for deformation monitoring. A key objective is to map patterns of locking and stable slipping of the megathrust, in order to constrain the likely down-dip limit of (future) seismic slip and identify any variations along the strike of the subduction zone. A secondary goal is to detect upper plate deformation associated with shallow crustal faults, magmatism, and landsliding.******Part B: Mapping upper plate faulting with airborne lidar***GPS measurements imply permanent shortening landward of the subduction zone, but the responsible upper plate faults are largely unknown. Signatures of past shallow earthquakes are contained within the topography, but are inaccessible to traditional photographic remote sensing due to dense vegetation. By leveraging existing lidar holdings and collecting our own new data from an unmanned aerial vehicle platform, we will peer beneath the forested cover for the first time. Our aims are to map upper plate faults, determine their sense and rate of slip through ensuing paleoseismic work, and establish their role in fore-arc deformation kinematics.******By collaborating with NRCan scientists at the nearby Pacific Geoscience Centre on both projects, we will ensure that results are translated into tangible societal benefits such as improvements to seismic monitoring capabilities and probabilistic seismic hazard assessments.