List of Contributors ix Preface xiii Acknowledgments xvii About the Companion Website xix Part I An Introduction to the EarthScope Networks 1 EarthScope Networks in Alaska and Northwestern Canada 3 Jeffrey T. Freymueller and Michael E. West 2 Perspectives on Transportable Array Alaska Background Noise Levels 15 Adam T. Ringler, Kasey Aderhold, Robert E. Anthony, Robert W. Busby, Andy Frassetto, Toshiro Tanimoto, and David C. Wilson Part II Synthesis Studies of Alaska and Northwestern Canada: From the Crust to the Lower Mantle 3 A Decade of Alaska Seismicity: 2013–2022 47 Natalia A. Ruppert 4 Updating the Crustal Fault Model for the 2023 National Seismic Hazard Model for Alaska 85 Peter J. Haeussler, Adrian M. Bender, Peter M. Powers, Richard D. Koehler, and Daniel S. Brothers 5 Geodetic Observations of Tectonic Deformation in Alaska and Western Canada: The EarthScope Revolution 129 Julie Elliott, Jeffrey T. Freymueller, and Ronni Grapenthin 6 Synthesis of the Seismic Structure of the Greater Alaska Region: Continental Lithosphere 185 Xiaotao Yang, Michael Everett Mann, Karen M. Fischer, Margarete A. Jadamec, Songqiao Shawn Wei, Gary L. Pavlis, and Andrew John Schaeffer Copyrighted Material 7 Structure, Origin, and Deformation of the Lithosphere in the Northern Canadian Cordillera From High-Resolution, Passive-Source Seismic Velocity Models 215 Clément Estève, Pascal Audet, Derek Leigh Schutt, Richard Craig Aster, Andrew John Schaeffer, and Joel F. Cubley 8 Synthesis of the Seismic Structure of the Greater Alaska Region: Subducting Slab Geometry 237 Gary L. Pavlis, Margarete A. Jadamec, Michael Everett Mann, Xiaotao Yang, Andrew John Schaeffer, Songqiao Shawn Wei, and Karen M. Fischer 9 Synthesis of the Seismic Structure of the Greater Alaska Region: Geodynamics Implications 267 Margarete A. Jadamec, Gary L. Pavlis, Xiaotao Yang, Karen M. Fischer, Songqiao Shawn Wei, Michael Everett Mann, and Andrew John Schaeffer Part III Aleutian–alaska Subduction: Properties, Interface Structure, and Dynamics 10 An Alaska–Aleutian Subduction Zone Interface Earthquake Recurrence Model From Geology and Geodesy 301 Rich Briggs, Robert C. Witter, Jeffrey T. Freymueller, Peter M. Powers, Peter J. Haeussler, Stephanie L. Ross, Tina Dura, Simon E. Engelhart, Richard D. Koehler, and Hong Kie Thio 11 TectonicTremorObservationsAcrossAlaska 325 Aaron G. Wech 12 Inherited Crustal Features and Southern Alaska Tectonic History Constrained by Sp Receiver Functions 335 Michael Everett Mann, Karen M. Fischer, and Jeffrey A. Benowitz 13 Implications of Variable Plate Coupling Versus Plateau Buoyancy on Subduction Dynamics: A Case Study of the Yakutat Plateau in Alaska 355 Kirstie L. Haynie and Margarete A. Jadamec 14 Constraining the Earthquake Recording Threshold of Intraslab Earthquakes With Turbidites in South-Central Alaska’s Lakes and Fjords 389 Drake M. Singleton, Daniel S. Brothers, Peter J. Haeussler, Robert C. Witter, and Jenna C. Hill 15 Variations in Reflection Signature and Slip Behavior of the Subduction Interface Offshore Alaska Peninsula From 152 ∘ to 161 ∘ W 419 Harold Kuehn, Mladen R. Nedimović, Donna J. Shillington, and Anne Bécel 16 Implications of the 2020–2021 Earthquakes for Megathrust Coupling and Seismicity in the Vicinity of the Shumagin Gap 445 Matthew W. Herman and Kevin P. Furlong Part IV Transform and Oblique Fault Systems: From the Plate-Boundary Corner to the Northeastern Brooks Range 17 Oblique Contraction Along the Fastest Ocean–Continent Transform Plate Boundary Focuses Rock Uplift West of the Fairweather Fault, Southeast Alaska 463 Robert C. Witter, Harvey M. Kelsey, Richard O. Lease, Adrian M. Bender, Katherine M. Scharer, Peter J. Haeussler, and Daniel S. Brothers 18 Slip Redistribution onto the Totschunda Fault of Southern Alaska: A Result of a Pacific Plate Motion Change at ca 6 Ma 497 Jacob L. Rosenthal, Paul G. Fitzgerald, Jeffrey A. Benowitz, James R. Metcalf, and Paul M. Betka 19 Inherited Upper-Plate Controls on Localized Arc Magmatism Since ca 100 Ma Along the Alaska Range Suture Zone 525 Jeffrey A. Benowitz and Michael Everett Mann 20 Geologic Evolution of the Denali Fault System and Associated Crustal Structure 547 Trevor S. Waldien, Meghan S. Miller, and Sarah M. Roeske 21 Seismicity and Anisotropic Imaging Reveal an Active Detachment Beneath the Northern Alaska Range Foothills 575 Vera Schulte-Pelkum, Adrian M. Bender, and Natalia A. Ruppert 22 The 2018 Kaktovik, Alaska Earthquakes and Their Context: Insights From Seismotectonics, InSAR Geodesy, and Static Stress Changes 589 Chris Rollins, Jeffrey T. Freymueller, Xueming Xue, Stephen G. Holtkamp, Thomas A. Logan, Franz Meyer, and Jason Patton Index 617

Tectonics and Seismic Structure of Alaska and Northwestern Canada EarthScope and Beyond The northwest of the North American continent is geologically dynamic and tectonically active. A network of seismic and geodetic instruments deployed across the region as part of the EarthScope project provided data crucial to understanding its geological, tectonic, and seismic processes. Tectonics and Seismic Structure of Alaska and Northwestern Canada: EarthScope and Beyond presents review papers and new scientific studies using EarthScope data to advance understanding of the region’s structure, seismic activity, and geodynamic processes. About this volume: Describes the infrastructure and capabilities of the EarthScope seismic and geodetic networksDraws from a comprehensive set of geophysical dataIncludes field studies, laboratory analyses, and numerical modelingSpans processes from the Earth’s interior and the lower mantle to the crust and surfaceCovers examples from subduction zones, fault systems, and some of the largest recorded earthquakesProvides scientific explanations for the natural landscapes and ongoing movements shaping the northwest of the North American continent The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.