EGU22-10161, updated on 28 Mar 2022
https://doi.org/10.5194/egusphere-egu22-10161
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Analysis of VLF and LF signal fluctuations recorded by Graz facility prior to earthquakes occurrences

Mohammed Y. Boudjada1, Pier Francesco Biagi2, Hans Ulrich Eichelberger1, Patrick H.M. Galopeau3, Konrad Schwingenschuh1, Maria Solovieva4, Helmut Lammer1, Wolfgang Voller1, and Masashi Hayakawa5
Mohammed Y. Boudjada et al.
  • 1Institut für Weltraumforschung, Extraterrestrial Physics, Graz, Austria (mohammed.boudjada@oeaw.ac.at)
  • 2Department of Physics, University of Bari, Bari, Italy
  • 3LATMOS-CNRS, UVSQ Université Paris-Saclay, Guyancourt, France
  • 4Institute of the Earth Physics, RAS, Moscow, Russia
  • 5Advanced Wireless Communications Research Center, University of Electro-Communications, Tokyo, Japan

We report in our study on earthquakes that occurred in Croatia and Slovenia in the period from 1 Jan. 2020 to 31 Dec. 2021. Those seismic events happened in a localized region confined between 13.46°E and 17.46°E in longitude and 45.03°N and 49.03°N in latitude. Maximum magnitudes Mw6.4 and Mw5.4 occurred, respectively, on 29 Dec. 2020, at 11:19 UT, and 22 March 2020, at 05:24 UT. We use two-radio system, INFREP (Biagi et al., 2019) and UltraMSK (Schwingenschuh et al., 2011) to investigate the reception conditions of LF-VLF transmitter signals. The selected earthquakes occurred at distances less than 300km from the Graz station (47.03°N, 15.46°E) in Austria. First, we emphasize on the time evolutions of earthquakes that occurred along a same meridian, i.e. at a geographical longitude of 16°E. Second, we study the daily VLF-LF transmitter signals that exhibit a minimum around local sunrises and sunsets. This daily variations are specifically considered two/three weeks before the occurrence of the two intense events with magnitudes Mw6.4 and Mw5.4. We discuss the unusual terminator time motions of VLF-LF signals linked to earthquakes occurrences, and their appearances at sunrise- or sunset-times. Such observational features are interpreted as disturbances of the transmitter signal propagations in the ionospheric D- and E-layers above the earthquakes preparation zone (Hayakawa, 2015).

 

References:

Biagi et al., The INFREP Network: Present Situation and Recent Results, Open J. Earth. Research, 8, 2019.

Hayakawa, Earthquake Prediction with Radio Techniques, John Wiley and Sons, Singapore, 2015.

Schwingenschuh et al., The Graz seismo-electromagnetic VLF facility, Nat. Hazards Earth Syst. Sci., 11, 2011

How to cite: Boudjada, M. Y., Biagi, P. F., Eichelberger, H. U., Galopeau, P. H. M., Schwingenschuh, K., Solovieva, M., Lammer, H., Voller, W., and Hayakawa, M.: Analysis of VLF and LF signal fluctuations recorded by Graz facility prior to earthquakes occurrences, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10161, https://doi.org/10.5194/egusphere-egu22-10161, 2022.