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Potential seismic hazards and tectonics of the upper Cook Inlet basin, Alaska, based on analysis of Pliocene and younger deformation

Geological Society of America Bulletin

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Abstract

The Cook Inlet basin is a northeast-trending forearc basin above the Aleutian subduction zone in southern Alaska. Folds in Cook Inlet are complex, discontinuous structures with variable shape and vergence that probably developed by right-transpressional deformation on oblique-slip faults extending downward into Mesozoic basement beneath the Tertiary basin. The most recent episode of deformation may have began as early as late Miocene time, but most of the deformation occurred after deposition of much of the Pliocene Sterling Formation. Deformation continued into Quaternary time, and many structures are probably still active. One structure, the Castle Mountain fault, has Holocene fault scarps, an adjacent anticline with flower structure, and historical seismicity. If other structures in Cook Inlet are active, blind faults coring fault-propagation folds may generate Mw 6-7+ earthquakes. Dextral transpression of Cook Inlet appears to have been driven by coupling between the North American and Pacific plates along the Alaska-Aleutian subduction zone, and by lateral escape of the forearc to the southwest, due to collision and indentation of the Yakutat terrane 300 km to the east of the basin.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Potential seismic hazards and tectonics of the upper Cook Inlet basin, Alaska, based on analysis of Pliocene and younger deformation
Series title:
Geological Society of America Bulletin
Volume
112
Issue:
9
Year Published:
2000
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geological Society of America Bulletin
First page:
1414
Last page:
1429
Number of Pages:
16