Skip to main content
U.S. flag

An official website of the United States government

Portable optically stimulated luminescence age map of a paleoseismic exposure

January 11, 2022

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.

Publication Year 2022
Title Portable optically stimulated luminescence age map of a paleoseismic exposure
DOI 10.1130/G49472.1
Authors Christopher DuRoss, Ryan D. Gold, Harrison J. Gray, Sylvia R. Nicovich
Publication Type Article
Publication Subtype Journal Article
Series Title Geology
Index ID 70230638
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center