Sudden modulation in the UHF wireless signals probably caused by the activation of pre‑earthquake processes. Case studies for the Balkans (SE Europe)

Article Sidebar

PDF
Published: Dec 31, 2023
DOI: https://doi.org/10.4401/ag-8990

Main Article Content

Dimitar Ouzounov
Chapman University
Sylvia Velichkova‑Yotsova
National Institute of Geophysics, Geodesy and Geography, Sofia, Bulgaria
Sergey Pulinets
Space Research Institute, Russian Academy of Sciences, Moscow, Russia

Abstract

We study the atmospheric variations of broadband wireless signal propagation intensity correlated with pre‑earthquake processes. We have maintained ground observations in the VHF range of 1.8 and 3.5 GHz in Bulgaria (Southeast Europe), close to the border with Greece and Northern Macedonia, since 2012. The signal source is 1.8 GHz –LTE broadcasting cellular communication signal and the receivers are digital HF to SHF antennae collecting the data via mobile internet. Our observations revealed phenomena associated with a natural enhancement of the intensity of the signals (no change in the transmitting level) days/hours before the seismic events, even far from the observation region. We are presenting the results for four significant earthquakes in the area: (1) M5.6 on May 22, 2012, in Bulgaria, (2) M6.9 on May 24, 2014, in the Aegean Sea, Greece, (3) M6.5 on Nov 17, 2015, Lefkada, Greece, and (4) M6.3 of May 12, 2017, in Western Türkiye. Some changes in the atmospheric boundary layer (ABL), triggered by an intensification of radon and other released gases, could lead to a change in lower atmospheric conductivity. Although the intensity modulation was observed far (> 200 km) from the epicenter areas, the anomalies were always inside the estimates of the Dobrovolsky‑Bowman area of preparation. We examined the possible correlation between magnitude and the spatial size of the earthquake preparation zone in the Lithosphere‑Atmosphere-Ionosphere coupling (LAIC) framework.

Article Details

How to Cite
Ouzounov, D., Velichkova‑Yotsova, S. . and Pulinets, S. (2023) “Sudden modulation in the UHF wireless signals probably caused by the activation of pre‑earthquake processes. Case studies for the Balkans (SE Europe)”, Annals of Geophysics, 66(6), p. SE647. doi: 10.4401/ag-8990.
Issue
Vol. 66 No. 6 (2023)
Section
Special Issue: Developments in Earthquake Precursors Studies
Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Open-Access License

No Permission Required

Istituto Nazionale di Geofisica e Vulcanologia applies the Creative Commons Attribution License (CCAL) to all works we publish.

Creative Commons License

Under the CCAL, authors retain ownership of the copyright for their article, but authors allow anyone to download, reuse, reprint, modify, distribute, so long as the original authors and source are cited. No permission is required from the authors or the publishers.

In most cases, appropriate attribution can be provided by simply citing the original article.
If the item you plan to reuse is not part of a published article (e.g., a featured issue image), then please indicate the originator of the work, and the volume, issue, and date of the journal in which the item appeared. For any reuse or redistribution of a work, you must also make clear the license terms under which the work was published.
This broad license was developed to facilitate open access to, and free use of, original works of all types. Applying this standard license to your own work will ensure your right to make your work freely and openly available. For queries about the license, please contact ann.geophys@ingv.it.