New Insights into Paleoseismic Age Models on the Northern San Andreas Fault: Charcoal Inbuilt Ages and Updated Earthquake Correlations

التفاصيل البيبلوغرافية
العنوان: New Insights into Paleoseismic Age Models on the Northern San Andreas Fault: Charcoal Inbuilt Ages and Updated Earthquake Correlations
المؤلفون: Ashley R. Streig, Glenn P. Biasi, Thomas P. Guilderson, Daniel G. Gavin, Ray J. Weldon, Timothy E. Dawson
المصدر: Bulletin of the Seismological Society of America. 110:1077-1089
بيانات النشر: Seismological Society of America (SSA), 2020.
سنة النشر: 2020
مصطلحات موضوعية: 010506 paleontology, Geophysics, 010504 meteorology & atmospheric sciences, San andreas fault, Geochemistry and Petrology, visual_art, visual_art.visual_art_medium, Charcoal, 01 natural sciences, Geology, Seismology, 0105 earth and related environmental sciences
الوصف: Dendrochronological age constraints at the Hazel Dell (HD) paleoseismic site provide a means to explore the potential for systematic bias in age estimates of earthquakes in forested settings including the Santa Cruz Mountains section of the San Andreas fault, California. Age constraints developed from detrital charcoal are compared with absolute dates from dendrochronology. We develop a new method for estimating inbuilt layer ages that makes use of more than just the youngest radiocarbon dates in a given layer. The improved age model relates likely layer deposition dates with observed C14 ages. We find that for HD, the most likely charcoal sample (mean) is ∼322 yr older than the actual age of the deposit that contains it. With this correction, two historical Bay area earthquakes are confirmed to have ruptured the surface in 1838 and 1890. Earlier work based on similar charcoal dates proposed these ruptures occurred in the mid-1700s or earlier, but historical ages of these events are unequivocal because they rupture layers containing wood chips and a redwood stump from European logging at the site. This charcoal correction method also shifts the fourth earthquake, which is constrained only by detrital charcoal, ∼300 yr younger to A.D. ∼1266. Considering the full site record at HD, recurrence of ground rupture has averaged ∼150 yr for the last four events, not ∼250 yr as inferred from unadjusted C14. Our research shows that reasonable estimates of inbuilt age can be made for charcoal-dominated paleoseismic sites and that correcting for the inbuilt age can make a significant difference for earthquake ages and potential correlations with other sites on the fault. We also examine other common inputs to Bayesian age models and find when adequate uncertainty is not incorporated, modeled ages may exclude the actual age of the event of interest.
تدمد: 1943-3573
0037-1106
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_________::90539e8d7bd69b6b7b7a41ad5efd9ddc
https://doi.org/10.1785/0120190307
رقم الأكسشن: edsair.doi...........90539e8d7bd69b6b7b7a41ad5efd9ddc
قاعدة البيانات: OpenAIRE