Ionospheric Irregularities caused by Acoustic Waves

Abstract

THIS communication presents some observational evidence for ionospheric irregularities being formed because of the propagation of acoustic waves. The acoustic waves themselves are believed to have been associated with an earthquake experienced at College, Alaska. During the past few years several studies have been devoted to the problem of the generation of acoustic and acoustic-gravity waves by an earthquake. Many of these studies followed in the wake of the Alaskan earthquake of 1964 (refs. 1–4). A number of travelling ionospheric disturbances were observed at different places after the earthquake and these disturbances are believed to be a manifestation of the propagating acoustic-gravity waves^5,6. Here we do not intend to explore the problem of the excitation of acoustic waves by an earthquake, and implicitly assume the existence of acoustic waves associated with an earthquake. This assumption seems to be justified in view of the earlier studies and also from our own observations.