SES-07. Testing microseismic Love wave generation mechanisms with amphibious seismic observations

Abstract
Microseismic waves are produced by wind-driven ocean waves interacting with the solid Earth. In contrast with earthquakes, microseismic waves are continuous and thus enable high-resolution imaging of the Earth's interior in both space and time. Surface waves (Rayleigh and Love waves) dominate microseismic signals, but the generation of Love waves is not well understood between 5 s and 10 s periods. Recent numerical models suggest that the ocean-land boundaries are essential in generating microseismic Love waves, via wave propagation effects such as focusing/defocusing, scattering, and Rayleigh-to-Love wave conversion. However, existing observations are mostly on land and thus unable to quantify wave propagation across the coast. To overcome this limitation, we use recent seismic deployment both onshore and offshore Cascadia (northwestern U.S.) and Alaska. Specifically, we characterize Love wave energy before, during, and after it hits the coast. Moreover, we compare the relative strengths between Love and Rayleigh waves to test if they are generated by the same mechanism. A better understanding for the generation of microseismic Love waves can not only improve 4-D imaging of the solid Earth, but also illuminate the interactions between atmosphere, oceans, and solid Earth.