Th long-term behavior of a narrow band peak near 26 sec in the micro-seismic background of the Earth has been studied over many years at several sites. The amplitude of this peak has been determined to be a function of the Earth's weather seasons; it is larger during the southern hemisphere winter. In addition, the microseismic background between 20 and 40 sec has been scanned for peaks in the spectra; three more lower-level peaks have been identified with the possible presence of more.
Additional publication details
Spectral structure in the Earth's microseismic background between 20 and 40 seconds