Holocene Rupture History of the Central Teton Fault at Leigh Lake, Grand Teton National Park, Wyoming

Prominent scarps on Pinedale glacial surfaces along the eastern base of the Teton Range confirm latest Pleistocene to Holocene surface-faulting earthquakes on the Teton fault, but the timing of these events is only broadly constrained by a single previous paleoseismic study. We excavated two trenches at the Leigh Lake site near the center of the Teton fault to address open questions about earthquake timing and rupture length. Structural and stratigraphic evidence indicates two surface-faulting earthquakes at the site that post-date deglacial sediments dated by radiocarbon and optically stimulated luminescence to similar to 10-11 ka. Earthquake LL2 occurred at similar to 10.0 ka (9.7-10.4 ka; 95% confidence range) and LL1 at similar to 5.9 ka (4.8-7.1 ka; 95%). LL2 predates an earthquake at similar to 8 ka identified in the previous paleoseismic investigation at Granite Canyon. LL1 corresponds to the most recent Granite Canyon earthquake at similar to 4.7-7.9 ka (95% confidence range). Our results are consistent with the previously documented long-elapsed time since the most recent Teton fault rupture and expand the fault's earthquake history into the early Holocene.