Tsunamigenic splay faults imply a long-term asperity in southern Prince William Sound, Alaska

Geophysical Research Letters
By: , and 



Coseismic slip partitioning and uplift over multiple earthquake cycles is critical to understanding upper‐plate fault development. Bathymetric and seismic reflection data from the 1964 Mw9.2 Great Alaska earthquake rupture area reveal sea floor scarps along the tsunamigenic Patton Bay/Cape Cleare/Middleton Island fault system. The faults splay from a megathrust where duplexing and underplating produced rapid exhumation. Trenchward of the duplex region, the faults produce a complex deformation pattern from oblique, south‐directed shortening at the Yakutat‐Pacific plate boundary. Spatial and temporal fault patterns suggest that Holocene megathrust earthquakes had similar relative motions and thus similar tsunami sources as in 1964. Tsunamis during future earthquakes will likely produce similar run‐up patterns and travel times. Splay fault surface expressions thus relate to plate boundary conditions, indicating millennial‐scale persistence of this asperity. We suggest structure of the subducted slab directly influences splay fault and tsunami generation landward of the frontal subduction zone prism.

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Publication type Article
Publication Subtype Journal Article
Title Tsunamigenic splay faults imply a long-term asperity in southern Prince William Sound, Alaska
Series title Geophysical Research Letters
DOI 10.1029/2018GL081528
Volume 46
Issue 7
Year Published 2019
Language English
Publisher American Geophysical Union
Contributing office(s) Alaska Science Center Geology Minerals, Pacific Coastal and Marine Science Center
Description 9 p.
First page 3764
Last page 3772
Country United States
State Alaska
Other Geospatial Prince William Sound
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