Portable optically stimulated luminescence age map of a paleoseismic exposure

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The quality and quantity of geochronologic data used to constrain the history of major earthquakes in a region exerts a first-order control on the accuracy of seismic hazard assessments that affect millions of people. However, evaluations of geochronological data are limited by uncertainties related to inherently complex depositional processes that may vary spatially and temporally. To improve confidence in models of earthquake timing, we use a high-density suite of radiocarbon and optically stimulated luminescence (OSL) ages with a grid of 342 portable OSL samples to explore spatiotemporal trends in geochronological data across an exemplary normal fault colluvial wedge exposure. The data reveal a two-dimensional age map of the paleoseismic exposure and demonstrate how vertical and horizontal trends in age relate to dominant sedimentary facies and soil characteristics at the site. Portable OSL data provide critical context for the interpretation of 14C and OSL ages, show that geochronologic age boundaries between pre- and post-earthquake deposits do not match stratigraphic contacts, and provide the basis for selecting alternate Bayesian models of earthquake timing. Our results demonstrate the potential to use emergent, portable OSL methods to dramatically improve paleoseismic constraints on earthquake timing.

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Publication type Article
Publication Subtype Journal Article
Title Portable optically stimulated luminescence age map of a paleoseismic exposure
Series title Geology
DOI 10.1130/G49472.1
Volume 50
Issue 4
Year Published 2022
Language English
Publisher Geological Society of America
Contributing office(s) Geologic Hazards Science Center
Description 6 p.
First page 470
Last page 475
Country United States
State Utah
Other Geospatial Deep Creek site, Wasatch fault zone
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