Depth‐Dependent Crustal Stress Rotation and Strength Variation in the Charlevoix Seismic Zone (CSZ), Québec, Canada

Intraplate tectonic stress fields are complex due to the imprint of a long geological history. Here we use new data set earthquake focal mechanism solutions and relocated events investigate relationship between regional stress, crustal strength, seismicity in Charlevoix Seismic Zone (CSZ), most active seismic zone eastern Canada. Our inversion shows that SHmax gradually rotates clockwise from approximately St. Lawrence River-parallel (∼54°) near surface river-perpendicular (∼120°) lower crust, as postglacial rebound becomes increasingly dominant at greater depth. The rotation occurs primarily ∼13 ∼26 km depth, where glacial induced perturbation is further amplified by “weaker” middle crust. Finally, depth-dependent b-values confirm rheological difference upper crust CSZ.