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An assessment of vertical land movement to support coastal hazards planning in Washington state

January 24, 2021

The sea and land change elevation spatially and temporally from a multitude of processes, so it is necessary to constrain the movement of both to evaluate how coastlines will evolve and how those evolving coastlines will impact the natural and built environment over time. We combine land movement observations from global navigation satellite systems (GNSSs), leveling of geodetic monuments, and tide gauge records with a tectonic model of the Cascadia subduction zone to constrain absolute rates of vertical land movement in coastal Washington. We infer rates of vertical land movement in areas lacking direct observations by interpolating high-quality land movement observations and a discretely sampled interseismic locking model. Here we present a model of absolute vertical land movement that is combined with sea level rise estimates to inform local relative sea level projections on a community-scale. The most rapid vertical uplift (~3.5 mm/year) of the land is found across the northwest Olympic Peninsula, which currently outpaces sea level rise. Conversely, some areas, including a stretch of the northern Pacific Ocean coast from La Push to Kalaloch and the southern Puget Sound, are found to be subsiding at 0.5–1.0 mm/year, exacerbating the rate of relative sea level rise and thereby increasing the vulnerability of coastal communities.

Publication Year 2021
Title An assessment of vertical land movement to support coastal hazards planning in Washington state
DOI 10.3390/w13030281
Authors Tyler Newton, Ray J. Weldon, Ian M. Miller, David Schmidt, Harriet Morgan, Eric Grossman, Guillaume S. Mauger
Publication Type Article
Publication Subtype Journal Article
Series Title Water (MDPI)
Index ID 70218298
Record Source USGS Publications Warehouse
USGS Organization Pacific Coastal and Marine Science Center