WITHDRAWN Investigating Interseismic Vertical Land Motion Along the Cascadia Subduction Zone Using High-resolution Diatom-based Paleogeodesy and Radiocarbon Chronologies
Description:
WITHDRAWN Along the Cascadia subduction zone (CSZ), intertidal wetlands preserve distinct stratigraphic evidence of past subduction zone earthquake-driven subsidence. Evidence for subsidence typically consists of a sharp transition from organic-rich peat (pre-earthquake) to a minerogenic tidal mud (post-earthquake), reflecting the rapid relative sea-level rise during great earthquakes. Paleogeodetic approaches using microfossils (e.g. diatoms and foraminifera) have enabled quantitative, high-precision reconstructions of coseismic subsidence that provide essential geologic constraints for modern rupture and tsunami models. However, comparatively little is known about vertical land motion (VLM) in the interseismic period, despite it being preserved within the same sedimentary sequences. In contrast, modern geodetic (GNSS) observations provide insights into present-day interseismic deformation and megathrust locking but are limited in resolution and do not capture long-term variability in coupling behavior.
Here, we aim to extend paleogeodetic reconstructions beyond the coseismic phase to resolve interseismic deformation across multiple earthquake cycles at three sites along the CSZ: Siletz Bay, Coquille River, and Sixes River. We use a diatom-based Bayesian transfer function to reconstruct paleoelevations from the immediate postseismic period through late-stage interseismic strain accumulation to inform patterns of strain accumulation. These VLM reconstructions will be coupled with high-resolution radiocarbon chronologies to add temporal constraints to VLM though the interseismic period. Together, these data provide new constraints on the evolution of CSZ megathrust locking and improve understanding of long-term vulnerability of coastal environments and communities.
Session: Linking Subduction Zone Processes and Cascading Hazards in Alaska, Cascadia, Chile and Beyond [Poster]
Type: Poster
Date: 4/16/2026
Presentation Time: 08:00 AM (local time)
Presenting Author: David Bruce
Student Presenter: No
Invited Presentation:
Poster Number: 124
Authors
David Bruce Presenting Author Corresponding Author bruced@vt.edu Virginia Polytechnic Institute and State University |
Tina Dura tinadura@vt.edu Virginia Polytechnic Institute and State University |
Andrea Hawkes hawkesa@uncw.edu University of North Carolina Wilmington |
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WITHDRAWN Investigating Interseismic Vertical Land Motion Along the Cascadia Subduction Zone Using High-resolution Diatom-based Paleogeodesy and Radiocarbon Chronologies
Category
Linking Subduction Zone Processes and Cascading Hazards in Alaska, Cascadia, Chile and Beyond