Propagation of microseisms from the deep ocean to land

Ocean-generated microseisms are faint Earth vibrations that result from pressure fluctuations at the sea floor generated by the interaction between ocean surface gravity waves, and are continuously recorded as low frequency seismic noise. Here we investigate microseism propagation away from deep-ocean source regions using the spectral element method for an oceanic model that contains realistic northeast Atlantic Ocean irregular-layered structure composed of water, sediment, and upper crust. It also includes structural heterogeneities and continental slope and shelf bathymetry. Numerical simulations of coupled acoustic and elastic wave propagation in both simplified models and the full realistic model show that most microseism energy is confined to sediment and water column waveguides. We also show that a significant portion of microseism energy is reflected back to the deep ocean by the continental slope, while only a small fraction of deep-ocean-generated microseism energy reaches land. We conclude that terrestrially observed microseisms are largely generated in shallow water on continental shelves.