Pc3 pulsations excited by earthquakes

Abstract Results of some event analyses and a common epoch analysis indicate a possible excitation of Pc3 magnetic pulsations by strong earthquakes when the hypocenters are on the dayside and under the land, i.e., inland earthquakes. The amplitude of the Pc3 starts to increase about 10–30 min after the origin time of earthquakes. This supports an idea that acoustic waves generated by ground motion and propagating to the ionosphere could be the source of the Pc3 activity in these cases. Near the longitude of the epicenter, the Swarm satellites observed compressional Pc3s of antiphase with ground observations and their power spectral densities (PSDs) were essentially the same as those observed on the ground. The PSD of the Pc3s has many spectral peaks and they are similar to those observed when the Swarm satellites encountered the Lamb wave propagated to the dayside after the Tonga undersea volcanic eruption on January 15, 2022. The Pc3s of solar wind origin also show similar spectra. These results suggest a possibility that the plasmaspheric cavity resonance essentially controls the frequencies of many PSD peaks of compressional Pc3. Graphical Abstract