Variation in natural short-period ionospheric noise... by Nina et al.

The results presented herein are based on analysis of the amplitudes of three VLF signals emitted in Italy, UK, and Germany and recorded in Serbia whose variations primarily result from changes in the electrical properties of the lower ionosphere at a distance more than 120km from the epicentre of the EQ.

1-min resolution

In the case of the 1-min sampling data, useful for analysis of long-term signal disturbances (daily variations) which can be attributed to an EQ event, we did not record changesin the global dailyamplitudetrends that are indicated as EQ precursors in previous studies; or their possible occurrences (terminator time shift) are masked by seasonal variations.

0.1-sec resolution

Short-term signal variations of the 0.1-sec sampling data were detected, which probably reflect the lower ionospheric disturbances. They are visualized as variations in the signals’ short-period noise amplitude which starts before the EQ and can be considered as an EQ precursor.

Nina A., Pulinets S., Biagi P.F., Nico G., Mitrović S.T., Radovanović M., Popović L.C., Variation in natural short-period ionospheric noise, and acoustic and gravity waves revealed by the amplitude analysis of a VLF radio signal on the occasion of the Kraljevo earthquake (Mw = 5.4). Science of the Total Environment 710 (2020) 136406. DOI:10.1016/j.scitotenv.2019.136406

#vlf