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Repeated Seismicity Conditions Paraglacial Valleys for Slope Failure in Prince William Sound, Alaska

Description: 

Paraglacial valley rock slopes in Prince William Sound, Alaska are located within a highly active seismic region and are susceptible to damage from earthquake shaking in conjunction with cycles of glaciation. We hypothesize that because ice is rigid at high co-seismic strain rates, glaciers buttress adjacent ice-contact rock slopes during earthquakes reducing seismic damage, and that as glaciers retreat, the portion of the rock slope susceptible to seismic damage increases. Repeated earthquakes over time thus help condition ice-free areas of paraglacial valleys for slope failure. We use numerical modeling to assess rock mass damage generated by seismic loading at times of different glacier elevations from the Last Glacial Maximum to present. Our models are based on in-situ conditions at Serpentine Glacier Valley, which contains several large, active landslides. Results show the evolution of spatially distributed rock slope damage generated by individual earthquakes, and how a history of repeated seismicity in Serpentine Valley generates rock mass damage conditioning areas of the slope for failure during present-day ice retreat. Glaciers buttress adjacent rock slopes during earthquakes reducing damage in areas of ice contact, while slopes above the glacier incur greater co-seismic fracturing. Over time, earthquake induced damage is maximized in areas that are most often ice free, as well as at slope breaks and crests susceptible to topographic amplification.

Session: Detecting, Characterizing and Monitoring Mass Movements [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Molly

Student Presenter: Yes

Invited Presentation: 

Authors