Earth noise, 5 to 500 millicycles per second: 2. Reaction of the Earth to oceans and atmosphere

Abstract

Sources of earth noise have been identified and located for different parts of the frequency band from 5 to 500 mc/s. In the typical microseism bands around 75 and 150 mc/s, sources are associated with storm waves arriving at both distant and local sea coasts. During the winter months the primary-frequency microseisms measured at La Jolla come mostly from the coast north of Cape Mendocino and are due to major storms in the North Pacific. Double-frequency microseism sources are generally within a few hundred kilometers of La Jolla, but more distant sources have also been observed. In addition, both ocean and atmosphere produce local loading which becomes significant at frequencies below the storm microseism band.