Earth and Planetary Sciences ETDs

Publication Date

Summer 7-28-2026

Abstract

The Alaska subduction zone, where the oceanic Pacific plate subducts beneath the continental North American plate at a rate of 60-66 mm/yr, has hosted more >M8 earthquakes over the last century than any other subduction zone globally. The largest of these, the 1964 M9.2 Alaska earthquake, ruptured 800 km of the margin, including a high slip patch near the trench offshore Kodiak Island. The 1964 rupture area may have overlapped with the 1938 M8.3 Semidi earthquake rupture zone that lies to the west. Slip propagation near the subduction trench during large earthquakes can control tsunamigenesis, and differences in wedge geometry can be related to varying slip propagation during an earthquake. Recently acquired multichannel seismic reflection data from the Alaska Amphibious Community Seismic Experiment (AACSE) provide new insights into along-strike variation in shallow structure and deformation of the frontal wedge where these historic earthquakes occurred. A continuous splay fault zone within the accretionary prism stretches along the length of the western 1964 Kodiak segment and the eastern portion of the 1938 Semidi segment, providing a medium for rupture propagation to the seafloor and across this segment boundary. Other components of the frontal wedge are found to be variable along strike, including deformation caused by subducting topography, frontal thrust vergence patterns, and input sediment heterogeneity due to mass transport deposits. These elements may have varying effects on shallow tsunamigenic rupture to the trench.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Dr. Lindsay Lowe Worthington

Second Committee Member

Dr. Eric Lindsey

Third Committee Member

Dr. Marisa Repasch

Language

English

Keywords

Alaska, subduction zone, accretionary prism, earthquake rupture, marine seismic reflection, structure

Document Type

Thesis

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