Studies of Teton Fault seismicity, using Mtn Front lake sediment data

April 5th (Tuesday), 6 p.m., Via Zoom (online) & (depending on Covid) Live at St. John’s Episcopal Church- Open to Public.
Presentation: “Studies of Teton Fault seismicity, using Mtn Front lake sediment data”
Presented by Darren Larsen, Occidental College

 Lakes in seismically active regions present valuable sedimentary archives of past seismic activity within their catchment and beyond. A series of glacially-excavated lakes positioned directly along the surface trace of the Teton fault at the base of the Teton Range, WY, are ideally situated to record fault activity since their formation ~15,000 years ago. The Teton fault is a major range-bounding normal fault that is recognized as one of the more active and hazardous faults in the Basin and Range Province, but which is also noted for its irregular postglacial paleoseismic history and relative quiescence during historical time. Previous work has demonstrated that earthquake events are registered in Teton lake sediment sequences as distinct, basin‐wide turbidite deposits that can be identified visually in core section and through changes in sediment physical character. Importantly, the ages of these diagnostic deposits can be correlated between multiple lakes and to the timing of surface rupturing earthquakes identified in fault trench excavations. 

We leverage this well-constrained system to conduct a detailed study of prominent turbidites in Jenny Lake at high-resolution to develop a better understanding of the stratigraphic expression of past earthquakes in Teton lakes. Jenny Lake is a relatively large (5 km2) and deep (~75 m max depth, ~45 m mean depth) glacially-carved basin located at the bottom of Cascade Canyon in the central Tetons, where postglacial slip rates are greatest. Based on our analyses, we create an interpretive model of turbidite formation and characterize sediment sources and transport pathways during past earthquake events. We further present emerging paleoseismic histories developed from four other nearby Teton lakes (Bradley, Taggart, Phelps, and Leigh Lakes) to highlight similarities and differences between these independent records.

Topic: Studies of Teton Fault Seismicity, Using Mtn Front Lake Sediment Data
Time: Apr 5, 2022 06:00 PM Mountain Time (US and Canada)

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Meeting ID: 455 565 1818
Passcode: 576063
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Meeting ID: 455 565 1818
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