Dynamic sea level variation from GNSS: 2020 Shumagin Earthquake Tsunami Resonance and Hurricane Laura

Rapid determination of sea level variations caused by tsunami or major storm surges is important for coastal hazard mitigation. Coastal GNSS stations at elevations less than ∼300 m can record time‐varying sea level changes by tracking signals that reflect from the sea surface relative to direct signals from the satellites. We demonstrate that such GNSS stations can rapidly provide local sea level measurements for a near‐field tsunami involving many hours of shelf resonance generated by the 2020 Shumagin earthquake as well as for the storm surge accompanying passage of the eye of Hurricane Laura over the Louisiana coast. Coastal GNSS stations deployed to measure tectonic deformation and co‐seismic displacements can inexpensively augment the spatial sampling provided by tide gauges for measuring tsunami‐induced coastal resonance and storm surges. This information can guide response activities during the crucial initial hours of an event.