Dynamic glacial and tectonic history of the Teton Range

July 17 (Tuesday), 6 p.m., T “Dynamic glacial & tectonic history of the Teton Range as recorded by lakes in GTN Park”, Presented by Darren Larsen, Occidental College.

The spectacular geomorphology and impressive relief of the Teton Range attract over 4 million visitors to Grand Teton National Park (GTNP) each year, and are attributed to ongoing displacement along the Teton fault. Well-preserved fault scarp exposures along the east side of the Range provide evidence for high normal fault activity since deglaciation, with fault displacement likely to have occurred through a series of large seismic events. While the majestic scenery of GTNP has benefitted from such tectonic activity, the potential for future large earthquakes and related slope failure events present hazards to Park visitors, infrastructure, and resource management efforts. A continuous and well-dated paleoseismic record of the Teton fault is crucial for assessing these hazards and evaluating the influence of tectonic activity on sedimentary systems. Yet despite considerable research efforts, the paleoseismic record of the Teton fault remains incomplete. This presentation will explore the use of sediment archives contained in lakes positioned adjacent to the Teton fault to provide a quantitative reconstruction of past earthquakes at GTNP (i.e. earthquake timing and frequency), including their impacts on sediment erosion (e.g. landslides, debris flows, slope failures) and future hazard potential. During a series of winter and summer field campaigns at GTNP, Larsen and colleagues have collected information related to the tectonic and environmental history of the Tetons using a combination of seismic surveys, high-resolution bathymetric mapping, and multiple lake cores collected from Jenny Lake and other seismically-sensitive lakes. Emerging results from these efforts demonstrate that Teton lakes provide continuous and well-dated records of tectonic activity and environmental conditions since their formation roughly 15,000 years ago. Video1 Video2