Contemporary deformation and stressing rates in Southern Alaska
The subduction of the Pacific Plate beneath North America induces broad scale stressing of the Alaskan crust that has led to the development of the highest mountains in North America, the highest slip rates along some of the longest strike-slip faults on Earth, and widespread seismicity that include...
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fthighwire:oai:open-archive.highwire.org:gji:183/2/557 2023-05-15T18:44:39+02:00 Contemporary deformation and stressing rates in Southern Alaska Ali, Syed Tabrez Freed, Andrew M. 2010-11-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/183/2/557 https://doi.org/10.1111/j.1365-246X.2010.04784.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/183/2/557 http://dx.doi.org/10.1111/j.1365-246X.2010.04784.x Copyright (C) 2010, Oxford University Press Geodynamics and Tectonics TEXT 2010 fthighwire https://doi.org/10.1111/j.1365-246X.2010.04784.x 2016-11-16T18:47:49Z The subduction of the Pacific Plate beneath North America induces broad scale stressing of the Alaskan crust that has led to the development of the highest mountains in North America, the highest slip rates along some of the longest strike-slip faults on Earth, and widespread seismicity that includes the 1964 M9.2 Alaska earthquake, the second largest ever recorded. These features are a consequence of deformation associated with three primary processes, interseismic loading due to relative plate motions, large earthquakes and post-seismic processes. How these mechanisms contribute to the evolution of stress in the Alaskan crust is not well understood. Here we use observed contemporary surface velocities to constrain 2-D and 3-D viscoelastic numerical models of relative Pacific/North American plate motions, coseismic slip associated with the 1964 (M9.2) megathrust event and strike-slip earthquakes on the transform boundary in 1949 (M8.1), 1958 (M7.8) and 1972 (M7.6) (the four largest events prior to the 2002 M7.9 Denali quake), viscoelastic relaxation following these events, and afterslip, to gain insight into how these processes are shaping Alaska today. Results suggest that interseismic deformation and on-going post-seismic deformation following the 1964 earthquake both contribute significantly to the GPS measured contemporary velocity field. Viscoelastic relaxation associated with a mantle with a viscosity of ∼1019 Pa s is required to explain southerly directed velocities that are observed in the Cook Inlet region to well north of the Denali fault. Results also suggest that subduction of the Pacific Plate leads to a broad zone of deformation with high stressing rates concentrated in a band that lies several hundred kilometres from the plate boundary, coeval with the inboard location of the maximum locking depth of the megathrust. Interseismic deformation and stressing rates remain high further inland across the Yakutat microplate, where flat subduction extends the width of the locked plate interface. ... Text Yakutat Alaska HighWire Press (Stanford University) Pacific Geophysical Journal International 183 2 557 571 |
institution |
Open Polar |
collection |
HighWire Press (Stanford University) |
op_collection_id |
fthighwire |
language |
English |
topic |
Geodynamics and Tectonics |
spellingShingle |
Geodynamics and Tectonics Ali, Syed Tabrez Freed, Andrew M. Contemporary deformation and stressing rates in Southern Alaska |
topic_facet |
Geodynamics and Tectonics |
description |
The subduction of the Pacific Plate beneath North America induces broad scale stressing of the Alaskan crust that has led to the development of the highest mountains in North America, the highest slip rates along some of the longest strike-slip faults on Earth, and widespread seismicity that includes the 1964 M9.2 Alaska earthquake, the second largest ever recorded. These features are a consequence of deformation associated with three primary processes, interseismic loading due to relative plate motions, large earthquakes and post-seismic processes. How these mechanisms contribute to the evolution of stress in the Alaskan crust is not well understood. Here we use observed contemporary surface velocities to constrain 2-D and 3-D viscoelastic numerical models of relative Pacific/North American plate motions, coseismic slip associated with the 1964 (M9.2) megathrust event and strike-slip earthquakes on the transform boundary in 1949 (M8.1), 1958 (M7.8) and 1972 (M7.6) (the four largest events prior to the 2002 M7.9 Denali quake), viscoelastic relaxation following these events, and afterslip, to gain insight into how these processes are shaping Alaska today. Results suggest that interseismic deformation and on-going post-seismic deformation following the 1964 earthquake both contribute significantly to the GPS measured contemporary velocity field. Viscoelastic relaxation associated with a mantle with a viscosity of ∼1019 Pa s is required to explain southerly directed velocities that are observed in the Cook Inlet region to well north of the Denali fault. Results also suggest that subduction of the Pacific Plate leads to a broad zone of deformation with high stressing rates concentrated in a band that lies several hundred kilometres from the plate boundary, coeval with the inboard location of the maximum locking depth of the megathrust. Interseismic deformation and stressing rates remain high further inland across the Yakutat microplate, where flat subduction extends the width of the locked plate interface. ... |
format |
Text |
author |
Ali, Syed Tabrez Freed, Andrew M. |
author_facet |
Ali, Syed Tabrez Freed, Andrew M. |
author_sort |
Ali, Syed Tabrez |
title |
Contemporary deformation and stressing rates in Southern Alaska |
title_short |
Contemporary deformation and stressing rates in Southern Alaska |
title_full |
Contemporary deformation and stressing rates in Southern Alaska |
title_fullStr |
Contemporary deformation and stressing rates in Southern Alaska |
title_full_unstemmed |
Contemporary deformation and stressing rates in Southern Alaska |
title_sort |
contemporary deformation and stressing rates in southern alaska |
publisher |
Oxford University Press |
publishDate |
2010 |
url |
http://gji.oxfordjournals.org/cgi/content/short/183/2/557 https://doi.org/10.1111/j.1365-246X.2010.04784.x |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Yakutat Alaska |
genre_facet |
Yakutat Alaska |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/183/2/557 http://dx.doi.org/10.1111/j.1365-246X.2010.04784.x |
op_rights |
Copyright (C) 2010, Oxford University Press |
op_doi |
https://doi.org/10.1111/j.1365-246X.2010.04784.x |
container_title |
Geophysical Journal International |
container_volume |
183 |
container_issue |
2 |
container_start_page |
557 |
op_container_end_page |
571 |
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1766235438577614848 |