Low Frequency Earth Motion Generated by Slowly Propagating, Partially Organized Pressure Fields

摘要

General expressions for the transfer function and the coherence relating earth motion and atmospheric pressure variations observed at the surface are derived for the case where the pressure field is a random process which is stationary in both time and space. It is found that as long as the phase velocities of the pressure field are low in comparison to seismic wave velocities this transfer function will be a smoothed version of the earth's response to a point pressure load applied at the surface. The form of the smoothing operator is determined by the correlation structure of the pressure field. In particular it was found that the transfer function of an analytical model which possesses all of the observed statistical properties of the wind generated pressure field closely resembles those associated with plane pressure waves. (Author)