Submarine slope failures associated - 1964 M9.2 Great Alaska Quake in fjords of southcentral Alaska

The March 27, 1964, Mw 9.2 Great Alaska Earthquake produced strong ground motions across coastal southcentral Alaska. In the fjords of Prince William Sound (PWS), which overlie the 1964 epicenter and rupture area, intense shaking generated widespread destabilization and failure of submerged fjord sediments. Some of these slope failures in turn generated devastating tsunamis that impacted several coastal communities. While sediments in some fjords failed in 1964, others did not, suggesting that a complex interplay between basin physiography, sediment accumulation, and shaking intensity determines the degree of instability that develops within each local fjord depositional system. This talk will highlight observations from a dataset of high-resolution Chirp sub-bottom profiles and shallow gravity cores recently collected across the fjords of southcentral Alaska. Using this dataset, we investigate factors that contributed to observed variations in the 1964 deposit character with the goal of quantifying the relationships between seismic parameters (i.e., shaking intensity), the sedimentary response (i.e., total volume remobilized and thickness of the resulting deposit), and the potential for a particular slide to generate a tsunami.
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