Atmospheric Pressure Waves and Tectonic Deformation Associated with the Alaskan Earthquake of March 28, 1964

Abstract

Atmospheric pressure disturbances with periods as long as 14 min have been recorded by sensitive microbarographs at five stations along the Pacific coast and at a station in Alaska after the great Alaskan earthquake of March 28, 1964. The phase and group velocities of the disturbances are consistent with those so far observed in atmospheric nuclear explosions and with theoretical dispersion curves for acoustic-gravity waves. These velocities and field observation of the tectonic deformations in the epicentral region suggest that the pressure disturbances might have been caused by the rapid vertical ground displacement at the source area. Theoretical barograms appropriate to the Berkeley station have been constructed on the basis of reasonable estimates for the source dimension, the amount of uplift and subsidence, and the time rate of the displacement, taking the atmospheric and instrumental responses into account. Agreement between general features of the observed and theoretical barograms appears sufficient to support the above generation hypothesis, suggesting a possible range for the time rate of the surface tectonic deformation.