A Comparison of Foraminifera and Diatom-based Transfer Function Estimates of Coseismic Subsidence During the 1700 CE Earthquake Along the Oregon Coast
Comparison of microfossil assemblages (e.g., diatoms and foraminifera) in pre- and post-earthquake intertidal sediment is the most widely applicable and precise means to measure coseismic subsidence during past plate-boundary earthquakes at subduction zones in temperate regions. Coseismic subsidence estimates derived from transfer functions—which use the empirical relationship between modern microfossil assemblages and elevation within the tidal frame—are critical input to earthquake and tsunami source models, especially at subduction zones like Cascadia that lack historically recorded great megathrust earthquakes (Mw8+). However, differences in uncertainties on subsidence estimates between diatoms and foraminifera have not been fully explored. For example, ecological processes affect different microfossil groups in different ways, such as differing reproductive rates, sediment mixing, dissolution, limited supratidal and subtidal range. To evaluate the potential impact of these and other processes on coseismic subsidence estimates, we will compare foraminiferal- and diatom-based transfer function estimates of coseismic subsidence during the ~M9 1700 CE earthquake at a series of sites along the Oregon coast. We will develop a diatom-based Bayesian transfer function (BTF) using a new modern dataset of >150 diatom samples from transects spanning the supratidal to subtidal zones of tidal wetlands along the Oregon and northern California coasts. We will then test the performance of the BTF on a sediment contact recording a known increase in sea-level rise (equivalent to ~1m of coseismic subsidence, as might occur during a ~Mw 8-9 earthquake) from a dike removal during restoration of a former salt marsh along the Coquille River in southern Oregon. Finally, we will apply our diatom-based BTF to the 1700 CE earthquake contact at Oregon coastal sites with foraminiferal-based BTF subsidence estimates. These results will help in evaluating past and future diatom- and foraminiferal-based estimates of subsidence, and their uncertainties, during past megathrust earthquakes.
Session: Frontiers in Earthquake and Tsunami Science - Model Integration, Recent Advances, Ongoing Questions [Poster]
Type: Poster
Room: Evergreen Ballroom
Date: 4/22/2022
Presentation Time: 08:00 AM Pacific
Presenting Author: Tina Dura
Student Presenter: No
Additional Authors
Tina Dura Presenting Author Corresponding Author tinadura@vt.edu Virginia Tech |
Eileen Hemphill-Haley ehhaley@gmail.com Humboldt State University |
Niamh Cahill niamh.cahill@mu.ie Maynooth University |
Harvey Kelsey harvey.kelsey@humboldt.edu Humboldt State University |
Andrea Hawkes hawkesa@uncw.edu University of North Carolina, Wilmington |
Isabel Hong isabel.hong@cwu.edu Simon Fraser University |
Simon Engelhart simon.e.engelhart@durham.ac.uk Durham University |
Robert Witter rwitter@usgs.gov U.S. Geological Survey |
Jason Padgett jason_padgett@my.uri.edu U.S. Geological Survey |
Alan Nelson anelson@usgs.gov U.S. Geological Survey, Golden, Colorado, United States |
Yvonne Milker yvonne.milker@uni-hamburg.de University of Hamburg, Hamburg, , Germany |
Benjamin Horton bphorton@ntu.edu.sg Nayang Technological University, Singapore, , Singapore |
A Comparison of Foraminifera and Diatom-based Transfer Function Estimates of Coseismic Subsidence During the 1700 CE Earthquake Along the Oregon Coast
Category
Frontiers in Earthquake and Tsunami Science - Model Integration, Recent Advances, Ongoing Questions
Description