We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The signature of accumulated permanent uplift, northern Cascadia subduction zone.
- Authors
Stanton, Kelsay M.; Crider, Juliet G.; Kelsey, Harvey M.; Feathers, James K.
- Abstract
Uplift of the overriding plate at a subduction zone denotes interseismic strain accumulation, which is subsequently released during a megathrust earthquake. Although most interseismic strain is thought to be released elastically, observations of uplifted coastal regions at subduction zones worldwide indicate that some strain may result in permanent uplift. The Grays Harbor and Willapa Bay (Washington, USA) coastal region of the Cascadia subduction zone hosts flights of marine terraces testifying to late Pleistocene rock uplift. Our new detailed mapping of the marine terraces recognizes nine new units, including estuarine and fluvial sediments. Luminescence dating, relative age based on soil maturity and terrace elevation, and an evaluation of previous ages from fossil shells collectively constrain the probable ages of three estuarine units to sea-level high stands during Marine Isotope Stages 5a, 5c, and 5e. We estimate an average uplift rate of 0.4 ± 0.1 mm/yr for the terraced estuarine units, consistent with other Pleistocene uplift and incision rates in Cascadia. When compared with observed interseismic vertical deformation, these rates suggest that about one-tenth of interseismic strain may become permanent. The values are permissible within the uncertainties of uplift based on regional estimates of interseismic vertical strain rates and of coseismic subsidence.
- Subjects
SUBDUCTION zones; THRUST faults (Geology); THERMOLUMINESCENCE dating; ESTUARINE sediments; STRAIN rate; EARTHQUAKES; LAND subsidence; PLEISTOCENE Epoch
- Publication
Quaternary Research, 2024, Vol 117, p98
- ISSN
0033-5894
- Publication type
Article
- DOI
10.1017/qua.2023.59