Abstract of discussion

Abstract

As early as 1921 the writer has pointed out that the propagation of microseisms in Europe is clearly affected by boundaries of major geological units. For example, microseisms originating near Scandinavia are propagated far into Asia without much loss of energy, but their amplitudes decrease considerably in southerly directions where surface layers of different geologic age and with different elastic constants are passed by the waves. Similarly, microseisms are well propagated across large parts of the United States. On the other hand, records of microseisms produced by hurricanes in the Caribbean area and recorded there at the stations of the United States Navy Department show 3ui the amplitudes of the microseisms decrease rapidly from one island to another.