Seismo Lab Seminar

The Chesapeake Bay, located on the East Coast of North America, is experiencing destructive levels of relative sea-level rise. Ample evidence suggests that the region lies on the former forebulge of the Laurentide Ice Sheet and that glacial isostatic adjustment (GIA) contributes to present-day land subsidence. We have recently reevaluated vertical land motions for the Chesapeake Bay using campaign and continuous GNSS observations spanning 2019–2023 along with the robust network imaging approach, which reveals widespread subsidence ranging from -2.97 to -0.40 mm/yr. In this work, we seek to isolate the effects of GIA from this new vertical land motion solution. Using the open-source Computational Infrastructure for Geodynamics software SELEN4.0, we developed a new radial viscosity model calibrated for the East Coast to predict GIA-driven vertical land motions in the Chesapeake Bay. Predicted rates of GIA contributions to the vertical land motion signal are on the order of -1.4 to -2.3 mm/yr, which comprise a substantial portion of the observed subsidence in the region. Removal of the GIA-driven signal from present-day subsidence rates reveals clear signals of coastal subsidence, with a maximum rate of -1.29 mm/yr. The results of this work underscore the importance of regular monitoring of vertical land motions and can be used to improve projections of relative sea-level changes as well as the associated coastal hazards for communities in the Chesapeake Bay region.