Microseisms recorded at Palisades, New York are investigated as to the source location, propagation paths, and relation to ocean wave heights. The source location is estimated from analysis of the incoming wave ground motion by using an analog correlator to compute the direction of propagation and then tracing this ray to a suspected meteorological-oceanographic source. The propagation path of Rayleigh waves approaching Palisades is determined, taking into account the geological and bathymetric structure of the western North Atlantic, and the resulting ray diagram is used to explain some to the source frequency observations. The amplitude of observed microseism is shown to be a function of the ocean wave heights in the suspected generating region and is a result of both refraction effects as well as apparently 'off the continental shelf' source locations. The principal conclusions are as follows: (1) The majority of sources producing microseisms at Palisades occur either in regions on the continental shelf to the east and northeast or off the continental shelf to the southeast, although the latter produce weaker signals. (2) The relative lack of sources in the region alsong the southeast coast on the continental shelf appears to be due to refraction effects. (3) The closer the origin is to the east or northeast on the continental shelf, the higher are the mocroseisms produced by given ocean waves although the relationship has too much scatter to allow ocean wave heights to be determined with great enough certainty from microseism observations. |