Sea Level Variations along the U.S. Pacific Northwest Coast: Tectonic and Climate Controls

Abstract

Abstract Analyses of the progressive multidecadal trends and climate-controlled annual variations in mean sea levels are presented for nine tide-gauge stations along the coast of the U.S. Pacific Northwest: Washington, Oregon, and Northern California. The trends in relative sea levels are strongly affected by the tectonics of this region, characterized by significant alongcoast variations in changing land elevations measured by benchmarks and global positioning system data. These combined data sets document the existence of both submergent and emergent stretches of shore. The Pacific Northwest sea levels are also affected by variations in the monthly mean seasonal cycles, with its extreme water levels occurring in the winter during strong El Ninos. To quantify this climate control and to derive improved multidecadal sea-level trends, separate evaluations of the winter and summer-averaged measured water levels have been undertaken. The resulting pair of linear regressions for each tide gauge shows a consis...