Infrasound: A new frontier in monitoring earthquakes

Infrasound has been widely used for observation of associated events such as earthquakes and volcanic eruptions, etc. The relatively low acoustic attenuation allows infrasound to transmit for a long distance from sources to propagate in the atmosphere at frequencies between 1 and 20 Hz and to be recorded regionally or globally. In addition, numerous data telemetered from the booming global networks of infrasound stations supply us a better understanding of the infrasound generation mechanism and remote effects of earthquakes. Recent efforts in source identification focus on the calculation methods of infrasonic data, considering propagation conditions including profiles of sound velocity and wind speed in the higher atmosphere. In turn, we can validate atmospheric model. In this paper, we place attention to several plausible generation mechanisms of distinct infrasound from earthquakes of different magnitudes, as well as the merits of infrasound arrays. Some detailed case studies are given at the end. On the basis of these studies, we will propose some feasible measures in future. It is no doubt that infrasound research will be an active field either for precursory earthquake infrasound or for co-, post-earthquake infrasound.