Paleoseismic Evidence for Climatic and Magmatic Controls on the Teton Fault, WY. Issue 22 (25th November 2019)

• Record Type: Journal Article
• Authors: Larsen, Darren J.; Crump, Sarah E.; Abbott, Mark B.; Harbert, William; Blumm, Aria; Wattrus, Nigel J.; Hebberger, John J.
• Is Part Of: Geophysical research letters. Volume 46:Issue 22(2019)
• Page Start: 13036
• Page End: 13043
• Publication Date: 2019-11-25
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL085475
• Languages: English
• ISSNs: 0094-8276

Abstract

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. Plain Language Summary: Paleoseismic reconstructions of past earthquake occurrence remain the primary method for determining patterns in fault dynamics through time and space and for developing accurate seismic hazard assessments. However, in many tectonically active environments, few reliable geologic archives exist, and the majority of paleoseismic records rely on trench excavations, which can be incomplete, discontinuous, and/or limited by large dating uncertainties. This study takes advantage of a unique geologic setting and integrates a suite of geophysical, geochronological, and sedimentological techniques to construct a continuous paleoseismic history of a dynamic intraplate fault and elucidate the connection between irregular earthquake recurrence patterns and external factors related to glacial‐interglacial climate changes and hotspot magmatism. Moreover, it advances the relatively nascent method of lake sediment paleoseismology, a promising tool for understanding fault patterns in time and space. Key Points: Precisely dated lake sediments and landslide deposits record past earthquakes along the Teton normal fault since deglaciation A series of seven major fault ruptures occurred at intervals of ~1, 050 years and followed by >5, 000 years of inactivity that continues today Our results are consistent with trench data and model simulations and suggest faulting was variably influenced by external factors