Tectonics and Seismic Structure of Alaska and Northwestern Canada E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Geophysical Monograph Series
• Sprache: Englisch

Seitenzahl: 2015

Veröffentlichungsjahr: 2024

Beschreibung

New insights into geologic and tectonic processes in Alaska and northwestern Canada

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 networks
• Draws from a comprehensive set of geophysical data
• Includes field studies, laboratory analyses, and numerical modeling
• Spans processes from the Earth’s interior and the lower mantle to the crust and surface
• Covers examples from subduction zones, fault systems, and some of the largest recorded earthquakes
• Provides 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.

Leseprobe

Table of Contents

Cover

Table of Contents

Title Page

Copyright

LIST OF CONTRIBUTORS

PREFACE

ACKNOWLEDGMENTS

ABOUT THE COMPANION WEBSITE

Part I: An Introduction to the EarthScope Networks

1 EarthScope Networks in Alaska and Northwestern Canada

1.1 INTRODUCTION

1.2 BACKGROUND, GOALS, AND pre-EarthScope STATUS

1.3 PLATE BOUNDARY OBSERVATORY CONSTRUCTION AND OPERATION

1.4 USArray TRANSPORTABLE ARRAY CONSTRUCTION AND OPERATION

1.5 LONG-TERM LEGACY OF EarthScope NETWORKS

1.6 CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

2 Perspectives on Transportable Array Alaska Background Noise Levels

2.1 INTRODUCTION

2.2 DATA

2.3 METHODS

2.4 OBSERVATIONS

2.5 DISCUSSION: FACTORS AFFECTING SEISMIC NOISE LEVELS ACROSS ALASKA AND NORTHWEST CANADA

2.6 FUTURE DEPLOYMENT CONSIDERATIONS

2.7 CONCLUSION

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

Part II: Synthesis Studies of Alaska and Northwestern Canada: From the Crust to the Lower Mantle

3 A Decade of Alaska Seismicity: 2013–2022

3.1 INTRODUCTION

3.2 ALEUTIAN ISLANDS AND ALASKA PENINSULA REGION

3.3 SOUTHCENTRAL ALASKA

3.4 SOUTHEAST ALASKA

3.5 INTERIOR ALASKA

3.6 NORTHEASTERN ALASKA

3.7 WESTERN ALASKA

3.8 BERING SEA

3.9 GLACIAL SEISMICITY

3.10 CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

4 Updating the Crustal Fault Model for the 2023 National Seismic Hazard Model for Alaska

4.1 INTRODUCTION

4.2 METHODS

4.3 DISCUSSION OF ACTIVE FAULTS BY REGION

4.4 DISCUSSION AND CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

5 Geodetic Observations of Tectonic Deformation in Alaska and Western Canada: The EarthScope Revolution

5.1 INTRODUCTION

5.2 GEODETIC SITES AND NETWORKS IN ALASKA

5.3 A BRIEF HISTORY OF UAF/MSU GPS DATA ANALYSIS

5.4 SIGNALS IN GPS DATA

5.5 EARTHQUAKE CYCLE DEFORMATION

5.6 GEODYNAMIC MODELS

5.7 IMPLICATIONS FOR ALASKA TECTONICS

5.8 CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

DATA REFERENCES

6 Synthesis of the Seismic Structure of the Greater Alaska Region: Continental Lithosphere

6.1 INTRODUCTION

6.2 DATA: COMPILATION OF SEISMIC MODELS

6.3 METHODS

6.4 RESULTS

6.5 DISCUSSION

6.6 CONCLUSIONS

ACKNOWLEDGMENTS

AUTHOR CONTRIBUTIONS

AVAILABILITY STATEMENT

REFERENCES

7 Structure, Origin, and Deformation of the Lithosphere in the Northern Canadian Cordillera From High-Resolution, Passive-Source Seismic Velocity Models

7.1 INTRODUCTION

7.2 SEISMIC VELOCITY STRUCTURE OF THE CRUST

7.3 SEISMIC VELOCITY STRUCTURE OF THE UPPER MANTLE

7.4 DISCUSSION

7.5 CONCLUSIONS AND PERSPECTIVE

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

8 Synthesis of the Seismic Structure of the Greater Alaska Region: Subducting Slab Geometry

8.1 INTRODUCTION

8.2 DATA

8.3 METHODS

8.4 RESULTS

8.5 DISCUSSION

ACKNOWLEDGMENTS

AUTHOR CONTRIBUTIONS

AVAILABILITY STATEMENT

REFERENCES

9 Synthesis of the Seismic Structure of the Greater Alaska Region: Geodynamics Implications

9.1 INTRODUCTION

9.2 EARTHSCOPE SEISMIC SYNTHESES

9.3 REVIEW OF CONTINUUM MODELING APPROACHES TO SUBDUCTION

9.4 INSIGHTS FROM GEODYNAMIC MODELING

9.5 CONCLUSIONS

ACKNOWLEDGMENTS

AUTHOR CONTRIBUTIONS

AVAILABILITY STATEMENT

REFERENCES

Part III: Aleutian–Alaska Subduction: Properties, Interface Structure, and Dynamics

10 An Alaska–Aleutian Subduction Zone Interface Earthquake Recurrence Model From Geology and Geodesy

10.1 INTRODUCTION

10.2 METHODS AND MODEL INPUTS

10.3 RESULTS BY FAULT SECTION

10.4 DISCUSSION

10.5 SUMMARY

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

11 Tectonic Tremor Observations Across Alaska

11.1 INTRODUCTION

11.2 DETECTING TREMOR

11.3 THE ALEUTIAN ARC

11.4 SOUTH-CENTRAL ALASKA

11.5 TRIGGERED TREMOR

11.6 DISCUSSION

11.7 CONCLUSIONS

ACKNOWLEDGMENTS

DATA AVAILABILITY

REFERENCES

12 Inherited Crustal Features and Southern Alaska Tectonic History Constrained by Sp Receiver Functions

12.1 INTRODUCTION

12.2 GEOLOGIC BACKGROUND

12.3 DATA AND METHODS

12.4 RESULTS

12.5 DISCUSSION

12.6 CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

13 Implications of Variable Plate Coupling Versus Plateau Buoyancy on Subduction Dynamics: A Case Study of the Yakutat Plateau in Alaska

13.1 INTRODUCTION

13.2 THE YAKUTAT PLATEAU IN THE ALEUTIAN–ALASKA SUBDUCTION ZONE

13.3 ANALYTIC CALCULATIONS OF THE LITHOSPHERIC STRUCTURE ASSOCIATED WITH THE YAKUTAT PLATEAU AND ADJACENT SEAFLOOR

13.4 NUMERICAL MODELING OF SUBDUCTION IN ALASKA TESTING EFFECT OF SIMPLIFIED PLATEAU ANOMALY VERSUS VARIABLE PLATE COUPLING

13.5 DISCUSSION

13.6 CONCLUSION

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

14 Constraining the Earthquake Recording Threshold of Intraslab Earthquakes With Turbidites in South-Central Alaska’s Lakes and Fjords

14.1 INTRODUCTION

14.2 BACKGROUND

14.3 METHODS

14.4 RESULTS

14.5 DISCUSSION

14.6 CONCLUSION

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

15 Variations in Reflection Signature and Slip Behavior of the Subduction Interface Offshore Alaska Peninsula From 152° to 161°W

15.1 INTRODUCTION

15.2 TECTONIC SETTING AND MEGATHRUST SEISMICITY

15.3 DATA ACQUISITION AND ANALYSIS

15.4 RESULTS

15.5 DISCUSSION

15.6 CONCLUSIONS

ACKNOWLEDEGMENTS

AVAILABILITY STATEMENT

REFERENCES

16 Implications of the 2020–2021 Earthquakes for Megathrust Coupling and Seismicity in the Vicinity of the Shumagin Gap

16.1 EARTHQUAKES AND COUPLING IN THE SHUMAGIN GAP REGION

16.2 MODELING EARTHQUAKE CYCLE DEFORMATION

16.3 MODEL RESULTS

16.4 DISCUSSION AND CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

Note

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

17.1 INTRODUCTION

17.2 SEISMOTECTONIC AND GEOLOGIC SETTING

17.3 RESEARCH APPROACH

17.4 RESULTS

17.5 DISCUSSION

17.6 CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

APPENDIX A

REFERENCES

18 Slip Redistribution onto the Totschunda Fault of Southern Alaska: A Result of a Pacific Plate Motion Change at ca. 6 Ma

18.1 INTRODUCTION

18.2 GEOLOGIC BACKGROUND

18.3 METHODS AND SAMPLING STRATEGY

18.4 RESULTS AND INTERPRETATION

18.5 DISCUSSION

18.6 CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

19 Inherited Upper-Plate Controls on Localized Arc Magmatism Since ca. 100Ma Along the Alaska Range Suture Zone

19.1 INTRODUCTION

19.2 GEOLOGIC BACKGROUND

19.3 METHODS

19.4 RESULTS

19.5 DISCUSSION

19.6 CONCLUSION

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

20 Geologic Evolution of the Denali Fault System and Associated Crustal Structure

20.1 INTRODUCTION

20.2 METHODS

20.3 GEOLOGIC AND GEOPHYSICAL SIGNATURE OF THE DENALI FAULT SYSTEM

20.4 SYNTHESIS

20.5 CONCLUSION

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

21 Seismicity and Anisotropic Imaging Reveal an Active Detachment Beneath the Northern Alaska Range Foothills

21.1 INTRODUCTION

21.2 RECEIVER FUNCTION ANALYSIS OF CONTRASTS IN ANISOTROPY WITH DEPTH

21.3 S-MINUS-P DELAY TIME SPACE COMPARISON OF SEISMICITY DEPTHS WITH STRUCTURAL CONTRASTS

21.4 FREQUENCY–MAGNITUDE DISTRIBUTION (

B

-VALUE) ANALYSIS

21.5 RESULTS

21.6 DISCUSSION

21.7 CONCLUSIONS

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

22 The 2018 Kaktovik, Alaska Earthquakes and Their Context: Insights From Seismotectonics, InSAR Geodesy, and Static Stress Changes

22.1 INTRODUCTION

22.2 AN INTEGRATED EARTHQUAKE CATALOG FOR NORTHEAST ALASKA

22.3 INSAR-BASED SLIP MODELING OF THE KAKTOVIK EARTHQUAKES

22.4 STATIC STRESS CHANGES FROM THE KAKTOVIK EARTHQUAKES

22.5 DISCUSSION

ACKNOWLEDGMENTS

AVAILABILITY STATEMENT

REFERENCES

INDEX

End User License Agreement

List of Tables

Chapter 1

Table 1.1 Site name translations for sites established after the 2002 Denali...

Chapter 3

Table 3.1 Parameters of 2013–2022 earthquake aftershock sequences and swarms...

Chapter 4

Table 4.1 Table of fault sections and attributes for the 2023 NSHM.

Chapter 5

Table 5.1 Summary of major earthquakes since 2004 that have useful displacem...

Chapter 6

Table 6.1 Seismic shear-wave velocity models synthesized in this study (orde...

Table 6.2 Crustal thickness models synthesized in this study (ordered by the...

Chapter 8

Table 8.1 List of seismic imaging results used for this synthesis. and r...

Chapter 10

Table 10.1 Geologic recurrence intervals.

Table 10.2 Geodetic recurrence data.

Chapter 13

Table 13.1 Seismic constraints on crustal thickness (), crustal P-wave velo...

Table 13.2 Proposed lateral boundary segments of the Yakutat oceanic plateau...

Table 13.3 List of numerical models of Alaska examined.

Table 13.4 Thermal and compositional dimensionalization parameters, for a fi...

Table 13.5 Details on the compositional structure of the partial Yakutat oce...

Table 13.6 Results from 3-D numerical models of subduction in Alaska.

Chapter 14

Table 14.1 Summary of event deposit characteristics.

Chapter 15

Table 15.1 Depth to continental Moho in the ALEUT study area.

Chapter 16

Table 16.1 Input fault parameters for calculating Coulomb stress changes.

Chapter 17

Table 17.1 Infrared stimulated luminescence (IRSL) age information (Witter...

Table 17.2 Icy point radiocarbon data (Witter and Bender, 2021).

Table 17.3 Comparison of Icy Point marine terrace slopes to modern shore pla...

Table 17.4 Parameters used to estimate tectonic uplift component of Holocene...

Table 17.5 Estimates of fault-normal shortening rates and dip slip per event...

Chapter 18

Table 18.1 Summary of U-Pb zircon data.

Table 18.2 Summary of apatite fission track data.

Table 18.3 Summary of apatite and zircon (U-Th)/He data.

Chapter 20

Table 20.1 Geographic features intersected by the Denali Fault.

List of Illustrations

Chapter 1

Figure 1.1 Map of seismic and geodetic EarthScope networks in Alaska and nor...

Figure 1.2 (a) Pre‐EarthScope GPS network map as of 2003, with the sites gro...

Figure 1.3 Seismic stations in Alaska and northwestern Canada. (a) Broadband...

Figure 1.4 Example PBO station (GRNX, Healy, AK). The GPS antenna is mounted...

Figure 1.5 (a) Schematic design of a typical TA station. (b) Site E26K locat...

Chapter 2

Figure 2.1 Map of Transportable Array (TA) Alaska stations used in this stud...

Figure 2.2 (a) Picture of TA Alaska station D22K (Ayikyak River, Alaska) on ...

Figure 2.3 Power spectral density (PSD) probability density function (PDF) f...

Figure 2.4 Vertical broadband PSD database completeness for the TA Alaska st...

Figure 2.5 (a) Median vertical component (channel BHZ) noise values of the P...

Figure 2.6 Select level 3 AQ(L3) ecoregions of Alaska as defined by the U.S....

Figure 2.7 (a) Median vertical component (channel BHZ) noise values of the P...

Figure 2.8 (a) Median vertical component (channel BHZ) noise values of the P...

Figure 2.9 (a) Median vertical component (channel BHZ) noise values of the P...

Figure 2.10 (a) Median vertical component (channel BHZ) noise values of the ...

Figure 2.11 (a) Median vertical component (channel BHZ) noise values of the ...

Figure 2.12 (a) Median PSD estimates from the vertical component at each sta...

Figure 2.13 (a) Median PSD estimates from the north–south component at each ...

Figure 2.14 (a) Map of station noise level differences between the median no...

Figure 2.15 (a) Map of station noise level differences between the median no...

Figure 2.16 (a) Box and whisker plot of station noise level differences betw...

Figure 2.17 (a) Map of station noise level differences between the median no...

Figure 2.18 (a) Seasonal temperature changes from TA Alaska station A36M (Sa...

Figure 2.19 Station map of TA Alaska (blue circles) with stations that show ...

Figure 2.20 (a) Photo of an aurora on 2 February 2019 09:11 UTC by Aaron Loj...

Figure 2.21 Comparison of total magnetic field and seismic PSDs for station ...

Figure 2.22 Comparison of total magnetic field (horizontal axes) and seismic...

Figure 2.23 (a) The 2.5th and 50th percentiles of the total magnetic field P...

Chapter 3

Figure 3.1 Map of regional seismic stations. Different symbols indicate pre-...

Figure 3.2 Seismicity map for Alaska and neighboring regions. The map includ...

Figure 3.3 Reference map for subsequent figures with region names and major ...

Figure 3.4 Map of significant earthquakes (magnitude 6 or greater) in the Al...

Figure 3.5 The 23 June 2014 M7.9 Little Sitkin Earthquake sequence. (a) Map ...

Figure 3.6 The 23 January 2018 M7.9 Offshore Kodiak Earthquake sequence. Map...

Figure 3.7 Map of seismicity in the region around the 22 July 2020 M7.8 Sime...

Figure 3.8 Density distribution of the 22 July 2020 M7.8 Simeonof and 29 Jul...

Figure 3.9 Cumulative number of earthquakes for all magnitudes (upper curve)...

Figure 3.10 Map of 2006–2020 crustal faulting earthquakes in western Aleutia...

Figure 3.11 Map of seismicity in southcentral Alaska. The map includes all t...

Figure 3.12 The 23 January 2016 M7.1 Iniskin Earthquake sequence. (a) Map of...

Figure 3.13 The 30 November 2018 M7.1 Anchorage Earthquake sequence. (a) Map...

Figure 3.14 Map of seismicity in southeast Alaska color coded by depth (tect...

Figure 3.15 The 5 January 2013 M7.5 Craig Earthquake sequence. Red circles a...

Figure 3.16 Map of the 17 July 2014 M6.0 Seward Glacier earthquake region. R...

Figure 3.17 Map of the 25 July 2014 M6.0 Palma Bay Earthquake region. Red ci...

Figure 3.18 Map of the 1 May 2017 M6.2 and M6.3 earthquake doublet in Britis...

Figure 3.19 Map of interior Alaska seismicity from the AEC earthquake catalo...

Figure 3.20 (a) Map of the 2014 Minto Flats Seismic Zone earthquake sequence...

Figure 3.21 (a) Map of the 2021 Salcha Seismic Zone earthquake sequence. Red...

Figure 3.22 Map of northeastern Alaska seismicity from the AEC earthquake ca...

Figure 3.23 (a) Map of the 2018–2019 Northeastern Brooks Range Swarm region....

Figure 3.24 (a) Cumulative number and (b) time–magnitude plots of events in ...

Figure 3.25 Map of western Alaska seismicity from the AEC earthquake catalog...

Figure 3.26 (a) Map of the 2014 Noatak Earthquake Swarm region. Red circles ...

Figure 3.27 (a) Map of the 2019–2022 Purcell Mountains Earthquake Swarm regi...

Figure 3.28 (a) Map of the 2015 and 2022 earthquake sequences near St. Georg...

Figure 3.29 Map of glacial quakes from the AEC catalog for 2013–2022. The in...

Figure 3.30 (a) Map of the Wright Glacier Earthquake Swarm region. Red circl...

Chapter 4

Figure 4.1 Quaternary faults and folds of Alaska (red lines and fault names)...

Figure 4.2 Fault sections and fault zone polygons of the 2023 NSHM update fo...

Figure 4.3 Example of fault mapping comparisons used to derive geologic faul...

Figure 4.4 Map from Elliott and Freymueller (2020) showing their geodetic mo...

Figure 4.5 Fault sections, zones, and interpreted upper-plate structure in t...

Figure 4.6 Diagram of structure offshore and southwest of the Shumagin Islan...

Figure 4.7 Large (M7+) intraslab earthquakes, deeper than 40 km, in Alaska r...

Figure 4.8 (a) Stratigraphic correlations of turbidites in cores from Eklutn...

Figure 4.9 Southeastern Alaska. Blue lines are 2023 NSHM fault sections. Whi...

Figure 4.10 Fault sections (blue lines) and the Pamplona fault zone polygon ...

Figure 4.11 Fault sections (blue lines) of the central, south-central, easte...

Figure 4.12 (a) The Natazhat thrust and Duke River Faults as a restraining b...

Figure 4.13 Fault sections (blue lines) and fault zones (blue-shaded polygon...

Figure 4.14 Seismicity lineaments of the Rampart, Minto Flats, Goldstream, F...

Figure 4.15 Preferred tectonic model for southern Alaska modified from Haeus...

Figure 4.16 Tectonics of the Bering Sea region from Mackey et al. (1997). Re...

Figure 4.17 Map and active crustal deformation rate profiles from the Yakuta...

Chapter 5

Figure 5.1 Tectonic Setting for Alaska and Western Canada. PFZ, Pamplona Fau...

Figure 5.2 Comparison between GPS/GNSS sites in 2008 at the time Freymueller...

Figure 5.3 North–South component of GPS time series for site AC13 on Chiriko...

Figure 5.4 Time series for site ATW2 in Palmer, Alaska (Figure 5.1), showing...

Figure 5.5 Interseismic velocities are from Elliott and Freymueller (2020a) ...

Figure 5.6 Interseismic velocities in the Chugach-St. Elias region and south...

Figure 5.7 Blocks and model predictions of block motions for Alaska and west...

Figure 5.8 Blocks and model predictions of block motions for the southeast p...

Figure 5.9 Interseismic velocities in interior Alaska from Elliott and Freym...

Figure 5.10 Coupling and rupture or aftershock areas of major earthquakes al...

Figure 5.11 (a) Coupling distribution model of Elliott and Freymueller (2020...

Figure 5.12 Focal mechanisms of M>5 earthquakes in Alaska over the past 15 y...

Figure 5.13 Displacements from the 2012 M7.8 Haida Gwaii earthquake, shown b...

Figure 5.14 Displacements from the 2013 M7.5 Craig earthquake, shown by vect...

Figure 5.15 Displacements from the 2014 Little Sitkin earthquake, shown by v...

Figure 5.16 Displacements from the 2016 M7.1 Iniskin earthquake, shown by ve...

Figure 5.17 Displacements from the 2017 Haines/Duke River earthquake doublet...

Figure 5.18 Displacements from the 2017 M7.8 Komandorsky earthquake, shown b...

Figure 5.19 Displacements from the 2018 M7.9 Offshore Kodiak earthquake, sho...

Figure 5.20 Map of aftershocks and moment tensor solutions following the 201...

Figure 5.21 Displacements from the 2018 M7.1 Anchorage earthquake, shown by ...

Figure 5.22 Displacements from the 2020 M7.8 Simeonof earthquake, shown by v...

Figure 5.23 Slip model and slip budget from Xiao et al. (2021)/with permissi...

Figure 5.24 Displacements from the 2020 M7.6 Sand Point earthquake, shown by...

Figure 5.25 Displacements from the 2021 Chignik earthquake, shown by vectors...

Figure 5.26 Predicted postseismic velocities due to the 1964 M9.2 Great Alas...

Figure 5.27 Postseismic displacements over time due to the 2002 M7.9 Denali ...

Figure 5.28 Coupling, past earthquakes, and slow slip events along the easte...

Chapter 6

Figure 6.1 Tectonic settings of Alaska. (a) Key tectonic settings of Alaska,...

Figure 6.2 Seismic stations in Alaska and coverage of the seismic velocity m...

Figure 6.3 Examples of the synthesized shear-wave velocity models at the dep...

Figure 6.4 Same as Figure 6.3 but at the depths of 60 km for W2018 and 80 km...

Figure 6.5 Single-station crustal thickness estimates from (a) Veenstra et a...

Figure 6.6 Multi-station continental crustal thickness estimates from (a) Ha...

Figure 6.7 Clustering of velocity profiles between 10 and 50 km depths. The ...

Figure 6.8 Same as Figure 6.7 but for velocity profiles at the depths of 40–...

Figure 6.9 Detected cluster boundaries from all velocity models. (a, b) Clus...

Figure 6.10 Major seismic velocity domains and the average velocity profiles...

Figure 6.11 Average crustal thicknesses from multiple models. (a) Average of...

Figure 6.12 Crustal thicknesses within the crustal (C1–C6) and mantle (M1–M6...

Figure 6.13 Comparison of velocity domains and major faults and tectonic ter...

Figure 6.14 Comparison of mantle lithospheric velocity domains (M1–M6 within...

Chapter 7

Figure 7.1 (a) Topographic map of western Canada and eastern Alaska. Red dot...

Figure 7.2 Seismic station coverage across northwestern Canada from January ...

Figure 7.3 20- and 30-km depth slices through the S-wave velocity models of ...

Figure 7.4 Profiles through the S-wave velocity models of (a,b) Kao et al. (...

Figure 7.5 Moho depth estimates across northwestern Canada obtained from Aud...

Figure 7.6 Maps showing azimuthal anisotropy of northwestern Canada at perio...

Figure 7.7 70-km depth slice through the S-wave velocity models of (a) Kao e...

Figure 7.8 Teleseismic P- and S-wave tomography models of northwestern Canad...

Figure 7.9 Station average core phase splitting parameters throughout northw...

Figure 7.10 (a,c) Low-velocity and (b,d) high-velocity vote maps at 20- and ...

Chapter 8

Figure 8.1 Tectonic setting of the Alaska subduction zone. The base map is a...

Figure 8.2 Tectonic event chart. The chart uses a linear timescale shown at ...

Figure 8.3 Constant depth slices of vote map data volume. Contours of Slab2....

Figure 8.4 Map showing locations of cross-sections AA'–GG'. Figure numbers c...

Figure 8.5 Cross-section AA' in the Yakutat–Wrangell region slicing through ...

Figure 8.6 Cross-section BB' through vote map image volume. The location of ...

Figure 8.7 Cross-section DD' through vote map image volume. This section pas...

Figure 8.8 Cross-section EE' of vote map data through the center of the flat...

Figure 8.9 Cross-section FF' of vote map data within Alaska but west of the ...

Figure 8.10 Cross-section GG' through vote map image of Aleutian slab geomet...

Figure 8.11 Cross-section CC' through vote map image in Yukon region. This s...

Figure 8.12 Interpretation of relative displacement between the shallow port...

Figure 8.13 Backprojections of Yakutat polygon showing first-order timing co...

Figure 8.14 Illustration of how a slab window linked to the extinct Kula rid...

Figure 8.15 Kinematic model interpretation of EarthScope TA imaging results....

Chapter 9

Figure 9.1 Tectonic setting of (a) the Aleutian–Alaska subduction zone in (b...

Figure 9.2 Tectonic setting of (a) the Aleutian–Alaska subduction zone in (b...

Figure 9.3 Major seismic structural domains of the continental lithosphere f...

Figure 9.4 Slab and upper-mantle votemaps from Pavlis et al. (2024). (a) Loc...

Figure 9.5 Schematic diagram of common approaches and regions of the Earth s...

Figure 9.6 Schematic diagrams of (a–c) trench retreat and advance, (d, e) en...

Figure 9.7 Schematic diagrams of factors in the downgoing plate (a,b), overr...

Figure 9.8 Three-dimensional, geographically referenced continuum models of ...

Figure 9.9 Geodynamic setting for the Alaska subduction zone with pre-EarthS...

Chapter 10

Figure 10.1 Study area along the Alaska–Aleutian subduction zone (AASZ) show...

Figure 10.2 Overview of the geodetic coupling model and plate boundary conte...

Figure 10.3 Detail of the Yakataga, Prince William Sound, Kenai, Barren Isla...

Figure 10.4 Detail of the Semidi, Shumagin, and Sanak sections along the AAS...

Figure 10.5 Detail of the Fox Islands, Andreanof, and Adak sections along th...

Figure 10.6 Detail of the Amchitka, Attu, and Komandorski sections along the...

Chapter 11

Figure 11.1 Map of the Alaska–Aleutian subduction zone. Regions where ambien...

Figure 11.2 Map of south-central Alaska modified from Wech (2016). Tremor ep...

Chapter 12

Figure 12.1 Overview of the study area. (a) Topographic map of the study reg...

Figure 12.2 Cross sections through the Sp CCP volume analyzed in this study....

Figure 12.3 Analysis of topography along the BRF and Contact Fault, and the ...

Figure 12.4 Schematic depicting snapshots through time of each of the three ...

Figure 12.5 Zoom-in of the Copper River Basin and subducting Yakutat slab te...

Chapter 13

Figure 13.1 Tectonic setting of the Alaska segment of the Aleutian–Alaska su...

Figure 13.2 Synthesized Yakutat plateau with seismic constraints. (a) Map of...

Figure 13.3 Temperature profile and thickness of the Pacific Plate and Yakut...

Figure 13.4 P-wave velocity–density relationships used to determine the dens...

Figure 13.5 Relationship between crustal basalt thickness versus depleted ma...

Figure 13.6 Schematic diagram of thickness and density for each layer of Yak...

Figure 13.7 Model setup for high-resolution 3-D numerical simulations of the...

Figure 13.8 Model-predicted horizontal velocity magnitude from reference and...

Figure 13.9 Model-predicted horizontal velocity and fault-parallel different...

Figure 13.10 Observed velocity (DeMets et al., 1994; Elliott et al., 2013; S...

Figure 13.11 Model-predicted dynamic topography from reference and simplifie...

Figure 13.12 Observed shortening and subsidence with normalized model-predic...

Figure 13.13 Model-predicted horizontal velocity shown for a subset of the m...

Chapter 14

Figure 14.1 (a) Map of the Cook Inlet region. Solid gold lines and star repr...

Figure 14.2 Bathymetric map of Skilak Lake with MMI contours (U.S. Geologica...

Figure 14.3 (a) Chirp profile (SK20-08) from Skilak Lake with high-amplitude...

Figure 14.4 CT-scan transect of Skilak Lake cores. The background varve sedi...

Figure 14.5 (a) High-resolution photographs and CT scans of four cores from ...

Figure 14.6 (a) Grain-size evolution through the 2018 (left column) and 2016...

Figure 14.7 Thickness distribution of turbidites observed in Skilak Lake cor...

Figure 14.8 CT-scan transect of Kenai Lake cores. Varves and event deposits ...

Figure 14.9 Upper 10 cm of cores KE21-01A and KE20-10A showing possible 2018...

Figure 14.10 Chirp profile (TS20-01 and TS20-02) from Tustumena’s proximal b...

Figure 14.11 (a) CT-scan transect across Tustumena Lake with Cs-137 profile....

Figure 14.12 (a) High-resolution photograph (left) and CT scan (right) of co...

Figure 14.13 (a) Longitudinal Chirp profile (CH21-59) from Chelatna Lake. In...

Figure 14.14 CT scans of cores CH21-20A, CH21-15A, and CH21-14A and high-res...

Figure 14.15 (a) Chirp profile Line-65 in Passage Canal. The hummocky surfac...

Figure 14.16 (a) Upper ∼8 cm of core BC-06A (CT scan) from Harriman Fjord. B...

Figure 14.17 (a) ShakeMap-derived MMI contours for the 2018, 2016, and 1964 ...

Chapter 15

Figure 15.1 ALEUT survey area with red lines showing the location of MCS ref...

Figure 15.2 Line 3 reflection profile. The extent of the plate interface ref...

Figure 15.3 Line 2-2R reflection profile. The extent of the plate interface ...

Figure 15.4 Zoom of plate boundary on Line 12b reflection profile. Top and b...

Figure 15.5 ALEUT MCS profiles with plate interface characterization based o...

Figure 15.6 Distribution of the thin (<2 km, red), transitional (2–5 km, ora...

Figure 15.7 Comparison of the area that has ruptured in megathrust earthquak...

Figure 15.8 Comparison between the distribution of the megathrust locking fr...

Chapter 16

Figure 16.1 Seismotectonics of the Shumagin Gap region of the Alaska–Aleutia...

Figure 16.2 Seismicity of the Simeonof, Sand Point, and Chignik earthquake s...

Figure 16.3 Seismicity over time in the Shumagin Gap region shown in Figure ...

Figure 16.4 Cumulative seismic moment release over time from 2019 to May 202...

Figure 16.5 Locking model geometry for the finite-element analysis. The mode...

Figure 16.6 (a) Coulomb stress changes from the 2020 Simeonof mainshock and ...

Figure 16.7 Examples of interseismic slip deficit accumulated in our models ...

Figure 16.8 Modeled effects of a locked versus unlocked Shumagin Gap on slip...

Figure 16.9 Modeled effects of varying coupling on a shallow asperity updip ...

Chapter 17

Figure 17.1 Active faults (red lines, barbs point down dip) along the Pacifi...

Figure 17.2 (a) Topographic and bathymetric digital elevation models along t...

Figure 17.3 (a) Geology along the Fairweather fault in Glacier Bay National ...

Figure 17.4 Geomorphic map of Icy Point interpreted from lidar DEM (Witter e...

Figure 17.5 Multichannel seismic profiles acquired south of Icy Point (Balst...

Figure 17.6 Topographic profiles of the west-side-up principal strand of the...

Figure 17.7 In the lower Kaknau Creek valley, periglacial deposits are prese...

Figure 17.8 Modeled timing of Kauknau Lake drainage, the age of the Terrace ...

Figure 17.9 Marine terrace elevation profiles; locations shown on index map ...

Figure 17.10 Shore-perpendicular topographic profiles west (left) and east (...

Figure 17.11 (a) Map of Icy Point marine terraces showing area of lidar topo...

Figure 17.12 Relative sea-level (RSL) curves for Icy Point (this study) and ...

Figure 17.13 (a) Oblique view looking to the northwest where the offshore Qu...

Chapter 18

Figure 18.1 Simplified terrane map of Alaska and the Northern Cordillera wit...

Figure 18.2 (a) Seismicity ranging from 0 to 15 km of depth from 1960 to the...

Figure 18.3 Geologic map of Lime Creek field area with sample locations (map...

Figure 18.4 Compiled geochronology and thermochronology from Lime Creek Bedr...

Figure 18.5 HeFTy modeled “good-fit” and “acceptable-fit”

T

–

t

envelopes for ...

Figure 18.6 Photo Collage. Note that facing directions are given in black te...

Figure 18.7 Schematic palinspastic reconstructions of strike-slip translatio...

Figure 18.8 (a) Compilation of the location tectonic and magmatic events acr...

Chapter 19

Figure 19.1 Modern configuration of the subducting slab and major terranes a...

Figure 19.2 Schematic depiction of the current Alaska eastern subduction zon...

Figure 19.3 Latitude versus age and age versus longitude for bedrock samples...

Figure 19.4 Probability density plots of compiled published bedrock ages and...

Figure 19.5 Compilations of magmatic ages in four main time periods. Map bac...

Figure 19.6 Compilations of ages in four main time periods. The map backgrou...

Figure 19.7 Compilations of ages in four main time periods for the apex of t...

Figure 19.8 Schematics of four distinct periods of Central Alaska Range Arc ...

Chapter 20

Figure 20.1 Satellite imagery map of Alaska and adjacent region of Canada em...

Figure 20.2 (a) Hillshade map of the region surrounding the Denali Fault rel...

Figure 20.3 Geologic assemblages and legend for the geologic map compilation...

Figure 20.4 (a) Moho depth estimates beneath stations (shown as colored dots...

Figure 20.5 Compiled geologic map for the region between Chatham Strait and ...

Figure 20.6 Compiled geologic map for the region between the Donjek and Slan...

Figure 20.7 Compiled geologic map for the region between the Slana and Delta...

Figure 20.8 Compiled geologic map for the region between the Delta and Middl...

Figure 20.9 Compiled geologic map for the region between the Middle River an...

Figure 20.10 Arctic DEM (nominal 2 m pixel resolution) hillshade images of s...

Chapter 21

Figure 21.1 Study location and seismotectonic setting. (a) Location of the n...

Figure 21.2 Morphotectonics of the Kantishna Hills anticline, modified from ...

Figure 21.3 Example of receiver function analysis at station KTH atop the Ka...

Figure 21.4

S

–

P

time profiles for seismicity near station KTH (Figure 21.2)....

Figure 21.5 (a) Depth profile for

b

-values for the Kantishna Hills cluster u...

Figure 21.6 Receiver function results in morphotectonic context. (a) White t...

Chapter 22

Figure 22.1 (a) Seismicity and tectonics of greater Alaska. Earthquakes are ...

Figure 22.2 Zoom-in of Figure 22.1a on the northeast Brooks Range. SM, Sadle...

Figure 22.3 Revisions to locations of post-2016.5 events in the vicinity of ...

Figure 22.4 (a) Cataloged earthquakes in the vicinity of the Kaktovik sequen...

Figure 22.5 Cataloged seismicity preceding and during the first day of the K...

Figure 22.6 Cataloged seismicity south of the Kaktovik sequence. (a) Seismic...

Figure 22.7 Original Sentinel-1A InSAR interferograms from Alaska Satellite ...

Figure 22.8 Quadtree downsampling of the InSAR data. (a,b) Unfiltered descen...

Figure 22.9 Rupture geometries explored for the Kaktovik earthquakes. (a) Mo...

Figure 22.10 Regularization elements used in inverting the InSAR data for fa...

Figure 22.11 Our first preferred slip model for the Kaktovik earthquakes, us...

Figure 22.12 Slip model using the rupture geometry based on mapped faults (F...

Figure 22.13 Our second preferred slip model for the Kaktovik earthquakes, u...

Figure 22.14 Slip model using the rupture geometry built from the inflection...

Figure 22.15 Static stress changes imparted by our first preferred (planar) ...

Figure 22.16 Static stress changes imparted by our second preferred (descend...

Guide

Cover

Table of Contents

Title Page

Copyright

List of Contributors

Preface

Acknowledgments

About the Companion Website

Begin Reading

Index

End User License Agreement

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Geophysical Monograph Series

239 Lithospheric Discontinuities

Huaiyu Yuan and Barbara Romanowicz (Eds.)

240 Chemostratigraphy Across Major Chronological Eras

Alcides N. Sial, Claudio Gaucher, Muthuvairavasamy Ramkumar, and Valderez Pinto Ferreira (Eds.)

241 Mathematical Geoenergy: Discovery, Depletion, and Renewal

Paul Pukite, Dennis Coyne, and Daniel Challou (Eds.)

242 Ore Deposits: Origin, Exploration, and Exploitation

Sophie Decree and Laurence Robb (Eds.)

243 Kuroshio Current: Physical, Biogeochemical and Ecosystem Dynamics

Takeyoshi Nagai, Hiroaki Saito, Koji Suzuki, and Motomitsu Takahashi (Eds.)

244 Geomagnetically Induced Currents from the Sun to the Power Grid

Jennifer L. Gannon, Andrei Swidinsky, and Zhonghua Xu (Eds.)

245 Shale: Subsurface Science and Engineering

Thomas Dewers, Jason Heath, and Marcelo Sánchez (Eds.)

246 Submarine Landslides: Subaqueous Mass Transport Deposits From Outcrops to Seismic Profiles

Kei Ogata, Andrea Festa, and Gian Andrea Pini (Eds.)

247 Iceland: Tectonics, Volcanics, and Glacial Features

Tamie J. Jovanelly

248 Dayside Magnetosphere Interactions

Qiugang Zong, Philippe Escoubet, David Sibeck, Guan Le, and Hui Zhang (Eds.)

249 Carbon in Earth’s Interior

Craig E. Manning, Jung-Fu Lin, and Wendy L. Mao (Eds.)

250 Nitrogen Overload: Environmental Degradation, Ramifications, and Economic Costs

Brian G. Katz

251 Biogeochemical Cycles: Ecological Drivers and Environmental Impact

Katerina Dontsova, Zsuzsanna Balogh-Brunstad, and Gaël Le Roux (Eds.)

252 Seismoelectric Exploration: Theory, Experiments, and Applications

Niels Grobbe, André Revil, Zhenya Zhu, and Evert Slob (Eds.)

253 El Niño Southern Oscillation in a Changing Climate

Michael J. McPhaden, Agus Santoso, and Wenju Cai (Eds.)

254 Dynamic Magma Evolution

Francesco Vetere (Ed.)

255 Large Igneous Provinces: A Driver of Global Environmental and Biotic Changes

Richard. E. Ernst, Alexander J. Dickson, and Andrey Bekker (Eds.)

256 Coastal Ecosystems in Transition: A Comparative Analysis of the Northern Adriatic and Chesapeake Bay

Thomas C. Malone, Alenka Malej, and Jadran Faganeli (Eds.)

257 Hydrogeology, Chemical Weathering, and Soil Formation

Allen Hunt, Markus Egli, and Boris Faybishenko (Eds.)

258 Solar Physics and Solar Wind

Nour E. Raouafi and Angelos Vourlidas (Eds.)

259 Magnetospheres in the Solar System

Romain Maggiolo, Nicolas André, Hiroshi Hasegawa, and Daniel T. Welling (Eds.)

260 Ionosphere Dynamics and Applications

Chaosong Huang and Gang Lu (Eds.)

261 Upper Atmosphere Dynamics and Energetics

Wenbin Wang and Yongliang Zhang (Eds.)

262 Space Weather Effects and Applications

Anthea J. Coster, Philip J. Erickson, and Louis J. Lanzerotti (Eds.)

263 Mantle Convection and Surface Expressions

Hauke Marquardt, Maxim Ballmer, Sanne Cottaar, and Jasper Konter (Eds.)

264 Crustal Magmatic System Evolution: Anatomy, Architecture, and Physico-Chemical Processes

Matteo Masotta, Christoph Beier, and Silvio Mollo (Eds.)

265 Global Drought and Flood: Observation, Modeling, and Prediction

Huan Wu, Dennis P. Lettenmaier, Qiuhong Tang, and Philip J. Ward (Eds.)

266 Magma Redox Geochemistry

Roberto Moretti and Daniel R. Neuville (Eds.)

267 Wetland Carbon and Environmental Management

Ken W. Krauss, Zhiliang Zhu, and Camille L. Stagg (Eds.)

268 Distributed Acoustic Sensing in Geophysics: Methods and Applications

Yingping Li, Martin Karrenbach, and Jonathan B. Ajo-Franklin (Eds.)

269 Congo Basin Hydrology, Climate, and Biogeochemistry: A Foundation for the Future (English version)

Raphael M. Tshimanga, Guy D. Moukandi N’kaya, and Douglas Alsdorf (Eds.)

269 Hydrologie, climat et biogéochimie du bassin du Congo: une base pour l’avenir (version française)

Raphael M. Tshimanga, Guy D. Moukandi N’kaya, et Douglas Alsdorf (Éditeurs)

270 Muography: Exploring Earth’s Subsurface with Elementary Particles

László Oláh, Hiroyuki K. M. Tanaka, and Dezsö Varga (Eds.)

271 Remote Sensing of Water-Related Hazards

Ke Zhang, Yang Hong, and Amir AghaKouchak (Eds.)

272 Geophysical Monitoring for Geologic Carbon Storage

Lianjie Huang (Ed.)

273 Isotopic Constraints on Earth System Processes

Kenneth W. W. Sims, Kate Maher, and Daniel P. Schrag (Eds.)

274 Earth Observation Applications and Global Policy Frameworks

Argyro Kavvada, Douglas Cripe, and Lawrence Friedl (Eds.)

275 Threats to Springs in a Changing World: Science and Policies for Protection

Matthew J. Currell and Brian G. Katz (Eds.)

276 Core-Mantle Co-Evolution: An Interdisciplinary Approach

Takashi Nakagawa, Madhusoodhan Satish-Kumar, Taku Tsuchiya, and George Helffrich (Eds.)

277 Compressional Tectonics: Plate Convergence to Mountain Building (Tectonic Processes: A Global View, Volume 1)

Elizabeth J. Catlos and Ibrahim Çemen (Eds.)

278 Extensional Tectonics: Continental Breakup to Formation of Oceanic Basins (Tectonic Processes: A Global View, Volume 2)

Ibrahim Çemen and Elizabeth J. Catlos (Eds.)

279 Strike-Slip Tectonics: Oceanic Transform Faults to Continental Plate Boundaries (Tectonic Processes: A Global View, Volume 3)

Ibrahim Çemen and Elizabeth J. Catlos (Eds.)

280 Landscape Fire, Smoke, and Health: Linking Biomass Burning Emissions to Human Well-Being

Tatiana V. Loboda, Nancy H. F. French, and Robin C. Puett (Eds.)

281 Clouds and Their Climatic Impacts: Radiation, Circulation, and Precipitation

Sylvia Sullivan and Corinna Hoose (Eds.)

282 Fast Processes in Large-Scale Atmospheric Models: Progress, Challenges, and Opportunities

Yangang Liu and Pavlos Kollias (Eds.)

283 Helicities in Geophysics, Astrophysics, and Beyond

Kirill Kuzanyan, Nobumitsu Yokoi, Manolis K. Georgoulis, and Rodion Stepanov (Eds.)

284 Noisy Oceans: Monitoring Seismic and Acoustic Signals in the Marine Environment

Gaye Bayrakci and Frauke Klingelhoefer (Eds.)

285 Alfvén Waves Across Heliophysics: Progress, Challenges, and Opportunities

Andreas Keiling (Ed.)

286 Salt in the Earth Sciences: Evaporite Rocks and Salt Deposition

Webster Mohriak

287 Salt in the Earth Sciences: Basin Analysis and Applications

Webster Mohriak

288 Microanalysis of Atmospheric Particles: Techniques and Applications

Joseph M. Conny and Peter R. Buseck (Eds.)

289 Distributed Acoustic Sensing in Borehole Geophysics

Yingping Li, Robert Mellors, and Ge Zhan (Eds.)

290 Tectonics and Seismic Structure of Alaska and Northwestern Canada: EarthScope and Beyond

Natalia A. Ruppert, Margarete A. Jadamec, and Jeffrey T. Freymueller (Eds.)

Geophysical Monograph 290

Tectonics and Seismic Structure of Alaska and Northwestern Canada

EarthScope and Beyond

Natalia A. Ruppert

Margarete A. Jadamec

Jeffrey T. Freymueller

Editors

This Work is a co-publication of the American Geophysical Union and John Wiley and Sons, Inc.

This edition first published 2025© 2025 American Geophysical Union

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Cover image: Geophysical monitoring station located at Barry Arm fjord in south-central Alaska. The site hosts both seismic and geodetic instrumentation. Courtesy of Daniel Diaz/Alaska Earthquake Center.Cover design: Wiley

LIST OF CONTRIBUTORS

Kasey Aderhold

EarthScope Consortium Inc.

Homer, AK, USA

Robert E. Anthony

Albuquerque Seismological Laboratory

U.S. Geological Survey

Albuquerque, NM, USA

Richard Craig Aster

Department of Geosciences

Colorado State University

Fort Collins, CO, USA

Pascal Audet

Department of Earth and Environmental Sciences

University of Ottawa

Ottawa, Canada

Anne Bécel

Lamont-Doherty Earth Observatory

Columbia University

Palisades, NY, USA

Adrian M. Bender

Alaska Science Center

U.S. Geological Survey

Anchorage, AK, USA

Jeffrey A. Benowitz

Department of Geological Sciences

University of Colorado Boulder

Boulder, CO, USA

Paul M. Betka

Atmospheric, Oceanic, and Earth Sciences Department

George Mason University

Fairfax, VA, USA

Rich Briggs

Geological Hazards Science Center

U.S. Geological Survey

Golden, CO, USA

Daniel S. Brothers

Pacific Coastal and Marine Science Center

U.S. Geological Survey

Santa Cruz, CA, USA

Robert W. Busby

EarthScope Consortium Inc.

Falmouth, MA, USA

Joel F. Cubley

Centre for Northern Innovation in Mining

Yukon University

Whitehorse, Canada

Tina Dura

Department of Geosciences

Virginia Tech

Blacksburg, VA, USA

Julie Elliott

Department of Earth and Environmental Sciences

Michigan State University

East Lansing, MI, USA

Simon E. Engelhart

Department of Geography

Durham University

Durham, UK

Clément Estève

Department of Meteorology and Geophysics

University of Vienna

Vienna, Austria

Karen M. Fischer

Department of Earth, Environmental, and Planetary Sciences

Brown University

Providence, RI, USA

Paul G. Fitzgerald

Department of Earth and Environmental Sciences

Syracuse University

Syracuse, NY, USA

Andy Frassetto

EarthScope Consortium Inc.

Washington, DC, USA

Jeffrey T. Freymueller

Department of Earth and Environmental Sciences

Michigan State University

East Lansing, MI, USA

Kevin P. Furlong

Department of Geosciences

Pennsylvania State University

University Park, PA, USA

Ronni Grapenthin

Geophysical Institute and Department of Geosciences

University of Alaska Fairbanks

Fairbanks, AK, USA

Peter J. Haeussler

Alaska Science Center

U.S. Geological Survey

Anchorage, AK, USA

Kirstie L. Haynie

Geologic Hazards Science Center

U.S. Geological Survey

Denver, CO, USA

Matthew W. Herman

Department of Geological Sciences

California State University

Bakersfield, CA, USA

Jenna C. Hill

Pacific Coastal and Marine Science Center

U.S. Geological Survey

Santa Cruz, CA, USA

Stephen G. Holtkamp

Geophysical Institute

University of Alaska Fairbanks

Fairbanks, AK, USA

Margarete A. Jadamec

Department of Geology and Institute for Artificial Intelligence and Data Science

University at Buffalo

Buffalo, NY, USA

Harvey M. Kelsey

Department of Geology

California State Polytechnic University, Humboldt

Arcata, CA, USA

Richard D. Koehler

Nevada Bureau of Mines and Geology

University of Nevada

Reno, NV, USA

Harold Kuehn

Department of Earth and Environmental Sciences

Dalhousie University

Halifax, Canada

and

Geosciences Department

Bundesgesellschaft für Endlagerung mbH (BGE)

Peine, Germany

Richard O. Lease

Alaska Science Center

U.S. Geological Survey

Anchorage, AK, USA

Thomas A. Logan

Geophysical Institute

University of Alaska Fairbanks

Fairbanks, AK, USA

Michael Everett Mann

Department of Earth, Environmental, and Planetary Sciences

Brown University

Providence, RI, USA

James R. Metcalf

Department of Geological Sciences

University of Colorado Boulder

Boulder, CO, USA

Franz Meyer

Geophysical Institute

University of Alaska Fairbanks

Fairbanks, AK, USA

Meghan S. Miller

Research School of Earth Sciences

Australian National University

Canberra, Australia

Mladen R. Nedimović

Department of Earth and Environmental Sciences

Dalhousie University

Halifax, Canada

Jason Patton

California Geological Survey

Sacramento, CA, USA

Gary L. Pavlis

Department of Earth and Atmospheric Sciences

Indiana University Bloomington

Bloomington, IN, USA

Peter M. Powers

Geological Hazards Science Center

U.S. Geological Survey

Golden, CO, USA

Adam T. Ringler

Albuquerque Seismological Laboratory

U.S. Geological Survey

Albuquerque, NM, USA

Sarah M. Roeske

Department of Earth and Planetary Sciences

University of California–Davis

Davis, CA, USA

Chris Rollins

GNS Science

Lower Hutt, New Zealand

Jacob L. Rosenthal

Department of Earth and Environmental Sciences

Syracuse University

Syracuse, NY, USA

Stephanie L. Ross

Pacific Coastal and Marine Science Center

U.S. Geological Survey

Moffett Field, CA, USA

Natalia A. Ruppert

Alaska Earthquake Center

University of Alaska Fairbanks

Fairbanks, AK, USA

Andrew John Schaeffer

Geological Survey of Canada

Natural Resources Canada

Sidney, Canada

Katherine M. Scharer

Earthquake Science Center

U.S. Geological Survey

Pasadena, CA, USA

Vera Schulte-Pelkum

Cooperative Institute for Research in Environmental Sciences and Department of Geological Sciences

University of Colorado Boulder

Boulder, CO, USA

Derek Leigh Schutt

Department of Geosciences

Colorado State University

Fort Collins, CO, USA

Donna J. Shillington

School of Earth and Sustainability

Northern Arizona University

Flagstaff, AZ, USA

Drake M. Singleton

Pacific Coastal and Marine Science Center

U.S. Geological Survey

Santa Cruz, CA, USA

Toshiro Tanimoto

Department of Earth Science and Earth Research Institute

University of California Santa Barbara

Santa Barbara, CA, USA

Hong Kie Thio

AECOM

Los Angeles, CA, USA

Trevor S. Waldien

Department of Geology and Geological Engineering

South Dakota School of Mines and Technology

Rapid City, SD, USA

Aaron G. Wech

Alaska Volcano Observatory

U.S. Geological Survey

Anchorage, AK, USA

Songqiao Shawn Wei

Department of Earth and Environmental Sciences

Michigan State University

East Lansing, MI, USA

Michael E. West

Geophysical Institute

University of Alaska Fairbanks

Fairbanks, AK, USA

David C. Wilson

Albuquerque Seismological Laboratory

U.S. Geological Survey

Albuquerque, NM, USA

Robert C. Witter

Alaska Science Center

U.S. Geological Survey

Anchorage, AK, USA

Xueming Xue

Department of Earth and Environmental Sciences

Michigan State University

East Lansing, MI, USA

Xiaotao Yang

Department of Earth, Atmospheric, and Planetary Sciences

Purdue University

West Lafayette, IN, USA

PREFACE

Alaska is a place of wonder and a source of inspiration for many. According to the Alutiiq Museum in Kodiak, Alaska, the name Alaska is derived from a word in Unangam Tunuu (the native language of the Aleut people) that is variously transliterated as Alaxsxix, Alas’kaak, or Alakshak. The meaning of the word is mainland or great land, and it refers to the large landmass found to the east of the Aleutian Islands.

Change typifies Alaska, from the onset of the winter and “termination dust” on the mountain peaks, to spring river breakup, to bursts of color from wildflowers bringing the mountainside to life. The change can be strong and swift but with it comes life. Change also means movement, from the movement of migrations, to the movement of the tectonic plates, to the movement of the mantle deep within and its manifestation through the outpouring of volcanoes on the surface. This movement of the plates can also lead to awe-inspiring mountain ranges evolving over millions of years and incomprehensible releases of energy leading to dramatic shifts of the Earth in a matter of seconds. Studying the structure and motion of this tectonically active region has impacts beyond the scientific community, reaching all that inhabit the remarkable and at times bewildering landscape.

There is also continuity across the national boundary between Alaska and northwestern Canada. This can be seen on the surface, for example, with the Yukon River originating in Canada and flowing across the Alaskan mainland out to the Bering Sea; with the geologic formations, mountain ranges, and ice fields straddling the border; or deep within the Earth where the asthenosphere flows beneath the North America plate underneath Alaska and Canada. There are connections and pathways of movement that transcend the borders, which naturally lend themselves to integrative science and joint efforts to discover how the natural world works—both at the surface and deep in the Earth’s interior.

The EarthScope project was a large-scale scientific initiative supported by the National Science Foundation aimed at understanding the geological, tectonic, and seismic processes of the North American continent and Earth’s underlying interior. An early component of the EarthScope project was the installation of a geodetic network across the western continental United States. In Alaska, this network was installed between 2004 and 2008, and most of the sites still continue to operate. One of the last components of the EarthScope project was the deployment of a network of instruments across Alaska and northwestern Canada. The data collected as a part of this last segment of EarthScope (from 2014 to 2021) have been crucial in advancing the understanding of the structure, seismic activity, and geodynamic processes of the region.

Tectonics and Seismic Structure of Alaska and Northwestern Canada: EarthScope and Beyond grew out of discussions from the 2017 EarthScope National Meeting in Anchorage, Alaska, and the 2021 Alaska EarthScope and Beyond synthesis workshop. This monograph brings together a collection of scientific studies and synthesis review papers on the large-scale and regional geologic and geophysical processes in Alaska and northwestern Canada that were catalyzed or constrained by the recent EarthScope data collection efforts. The research encompassed within this monograph represents countless hours of independent and collective research by faculty, students, researchers, and volunteers—ranging from remote field studies in the wilderness of Alaska and northwestern Canada, to analysis in the laboratory, to numerical models requiring high-performance computing.

The chapters in this volume are grouped into four parts: (1) An Introduction to the EarthScope Networks; (2) Synthesis Studies of Alaska and Northwestern Canada: From the Crust to the Lower Mantle; (3) Aleutian–Alaska Subduction: Properties, Interface Structure, and Dynamics; and (4) Transform and Oblique Fault Systems: From the Plate-Boundary Corner to the Northeastern Brooks Range.

Part I, An Introduction to the EarthScope Networks, presents an overview of the EarthScope networks in Alaska and northwestern Canada, including the pre- and post-EarthScope infrastructure and the stations most affected by noise. Chapter 1 provides background on the pre-EarthScope status and the construction, operation, and legacy of the geodetic and seismic components. Chapter 2 details noise characteristics of new and upgraded stations within the USArray seismic network. These stations were installed using similar techniques and made use of instruments with similar self-noise levels, providing a unique opportunity to evaluate how geographic location influences seismic background noise across Alaska.

Chapters 3–9—comprising Part II, Synthesis Studies of Alaska and Northwestern Canada: From the Crust to the Lower Mantle—are comprehensive studies that span the broader region of Alaska and northwestern Canada. The chapters are organized to successively probe deeper into the Earth’s interior, beginning with the crust and continuing into the lower mantle.

Chapter 3 reviews a decade of seismicity in Alaska by systematically synthesizing seismicity through the regions of mainland Alaska and the Aleutians. USArray stations deployed in Alaska recorded the largest earthquakes of the entire project and active seismic swarms with greatly improved accuracy and resolution. Chapter 4 presents the most up-to-date crustal fault model for Alaska that was used for the National Seismic Hazard Mapping Project. Chapter 5 provides a greatly expanded geodetic dataset, yielding an unprecedented view of deformation along the north Pacific margin and of the continental interior for interseismic, coseismic, and postseismic periods. Chapter 6 introduces synthesis models for the continental crust and lithosphere based on the quantitative comparison of published three-dimensional shear wave models and crustal thickness studies using EarthScope data. Chapter 7 focuses on lithosphere structure in the Canadian Cordillera as imaged by seismic data. Chapter 8 is an EarthScope seismic synthesis study that analyzes previous teleseismic shear wave models and receiver function imaging studies. For this study, the researchers produced vote maps to evaluate the mantle and subducted lithosphere structure beneath mainland Alaska and northwestern Canada. Chapter 9 builds on the seismic syntheses studies in Chapters 6 and 8 by detailing implications for geodynamics, providing a summary of previous geodynamic studies in Alaska, and placing the Alaska–Aleutian subduction dynamics in the broader context of the Pacific Ring of Fire.

As described in Part III, Aleutian–Alaska Subduction: Properties, Interface Structure, and Dynamics, the Aleutian–Alaska subduction zone is one of the Earth’s major subduction zones. It is characterized by oblique convergence, variable slab dip, and the ongoing subduction collision of the Yakutat plateau. It is also the site of the world’s second largest recorded earthquake. The properties of the subduction interface play an important role in modulating the short- and long-term tectonics. Part III brings together studies that focus on the plate interface properties as well as slab properties and related dynamics.

Chapter 10