Paleoseismic Evidence for Climatic and Magmatic Controls on the Teton Fault, WY

Abstract

Geologic records of past earthquakes are rare but critical for identifying long-term patterns in fault behavior and assessing modern earthquake hazards. We present a continuous 14,000-year paleoearthquake reconstruction using precisely dated lacustrine sediments and landslide deposits from a lake basin positioned directly on the Teton normal fault, which cuts across Grand Teton National Park, WY, and is among the most hazardous intraplate faults in the western United States. We show that beginning immediately after deglaciation, a series of at least seven major fault ruptures occurred at regular intervals of ~1,050 years (± ~250 years), followed by >5,000 years of inactivity. These results are consistent with trench data and model simulations and suggest that faulting was variably influenced by climate-controlled glacial fluctuations and magmatic activity of the nearby Yellowstone hotspot.