Ground-coupled air waves from the Great Alaskan Earthquake

Micropressure fluctuations occurring at the same time as the arrival of seismic waves were recorded at many localities following the Alaskan earthquake of March 27, 1964. It is shown that at Palisades, New York, Berkeley, California, and Honolulu, Hawaii, the pressure waves were produced by vertical ground motion associated with local Rayleigh waves arriving from the epicenter. Group velocity dispersion curves typical of Rayleigh wave modes for continental and oceanic paths, respectively, are developed from the air waves from the first two localities. Both oceanic and continental Rayleigh modes are indicated for Berkeley. A later train of waves arrived at a time appropriate for acoustic travel through the atmosphere directly from the epicenter. Although reminiscent of acoustic waves from large explosions, their generation over the large region of vertical ground displacement complicates their study.