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Potential Effects of the 1983 M6.9 Borah Peak Earthquake on Nearby Lakes

Description: 

Lacustrine sedimentary archives can improve estimates of prehistoric earthquake timing and intensity, but doing so requires modern analogues to understand how lakes respond to intense shaking, especially across diverse basin types and environments. The 1983 M6.9 Borah Peak earthquake in central Idaho remains one of the largest intraplate earthquakes in the United States. Here, we revisit sediment cores previously collected from multiple Holocene lakes in this region. The lakes exist (either fully or partially) within the slope-failure prone Eocene Challis Volcanic Group and many of the lakes are landslide dammed. While the original cores were designed to investigate longer-term Holocene sedimentation and watershed response to climate and lake formation, we hope to gain insight to paleoseismic activity using the Borah Peak earthquake as a historic analogue. As the original work entertained the possibility for landslide-dammed lakes to have a seismic origin, the numeric chronologies from these lakes demonstrated that they formed asynchronously, deeming failure by regional strong shaking unlikely. Furthermore, mass movements of similar type and scale were not documented due to intense shaking from the Borah Peak earthquake. Our goal is to assess whether these lakes archive a response to seismic shaking within their sedimentary records by analyzing surface drives for a subset of the lakes within the modeled Modified Mercalli Intensity (MMI) range of VI to VII½ for the Borah Peak earthquake. Additionally, we hope to use the previously characterized lake chemistry and sedimentation to assess additional variables that may influence the sensitivity of lacustrine systems to earthquake shaking when relating the earthquake records from each lake. These data will contribute to the growing catalogue of historic analogues of seismically disturbed lakes in the Intermountain West and comparable intraplate settings.

Session: Subaqueous Evidence for Earthquakes, Coseismic Landslides, Tsunamis and other Cascading Hazards [Poster]

Type: Poster

Date: 4/15/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Sylvia R. Nicovich

Student Presenter: No

Invited Presentation: 

Poster Number: 164

Authors