EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Observations of uplift and subsidence along the North American Pacific coast – illuminating the geodynamic complexity of an active margin

Maryam Yousefi1, Glenn Milne2, Shaoyang Li3, Kelin Wang4, Alan Bartholet2, Ryan Love5, and Lev Tarasov5
Maryam Yousefi et al.
  • 1McGill University, Earth and Planetary Sciences, Canada (
  • 2Department of Earth and Environmental Sciences, University of Ottawa. Ottawa, ON K1N 6N5, Canada
  • 3Earthquake Research Institute, University of Tokyo, 1 Chome-1-1 Yayoi, Bunkyo City, Tokyo, Japan, 113-0032.
  • 4Pacific Geoscience Centre, Geological Survey of Canada, 9860 West Saanich Road, Sidney, BC, Canada, V8L 4B2.
  • 5Department of Physics and Physical Oceangraphy, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada

The Pacific Coast of Central North America is a geodynamically complex region subject to various geophysical processes with different patterns of vertical land motion. It includes two distinct tectonic regimes: the Cascadia subduction zone and the strike-slip San Andreas fault system. The vertical land motion in this region reflects not only tectonic activity of these plate boundaries, but also isostatic signals associated with different loading effects such as the (de)glaciation of North American ice sheets and the more contemporary, anthropogenically-related groundwater extraction and mountain glacier mass loss. These processes occur over a broad range of timescales and are observed by a variety of measuring techniques.

Here we combine geological measurements of relative sea level (RSL) change with contemporary observations of vertical land motion inferred from geodetic data to decipher and thus better understand the contribution from various individual processes. Our results suggest that contemporary vertical land motion is dominated by Cascadia interseismic deformation and the isostatic response to the retreat of the North American ice sheets but is also influenced by other contemporary processes. We present some model results that illustrate the contributions of the above-mentioned processes to RSL projections along this coastline.  

How to cite: Yousefi, M., Milne, G., Li, S., Wang, K., Bartholet, A., Love, R., and Tarasov, L.: Observations of uplift and subsidence along the North American Pacific coast – illuminating the geodynamic complexity of an active margin, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12174,, 2021.

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