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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-24 21:10 |
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Conference: Bucharest University Faculty of Physics 2010 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Preliminary results of the INFREP European VLF/LF radio monitoring network installed in 2009: the Romanian contribution
Authors:
Iren-Adelina Moldovan (1), A. Moldovan (2), Anica Otilia Placinta (1) and Pier Francesco Biagi (3)
Affiliation:
(1) National Institute for Earths Physics, Seismological dept., Bucharest, Magurele, Romania (iren@infp.ro)
(2) AZEL - Designing Group S.R.L., Bucharest, Magurele, Romania (adrian@azel.ro)
(3)University of Bari, Department of Physics, Bari, Italy (t.maggipinto@fisica.uniba.it)
E-mail
iren@infp.ro
Keywords:
VLF/LF radio monitoring network
Abstract:
In January 2009 a European network of radio receivers able to measure the electric field intensity from various VLF/LF broadcasting stations located throughout Europe, was installed. Five new receivers constructed by an Italian enterprise have been delivered to Greece, Romania, Turkey and to the Italian team. After a necessary testing period of one year, each one of the receivers is monitoring up to ten different transmissions of radio stations across the continent and the LF/VLF radio signals are now simultaneously and continuously being sampled.
The motivation of this effort was to study the possible connections between the preparatory phase of earthquakes and perturbations in the transmitted radio signals. Information on electromagnetic fields intensities created by transmitters at each receiving site and gathered from this network are indicating the quality of the propagation along the paths between the receivers and transmitters. Studying the ionospheres influences on the electromagnetic waves propagation along a certain path is a method to put into evidence possible modifications of its lower structure and composition as earthquakes precursors.
The VLF / LF receiver installed in Romania was put into operation in February 2009 and has proved its utility in the case of Abruzzo earthquake that occurred on 6th of April 2009 (M=6.3) . Since then, the receiver was relocated from Bucharest to the Black-Sea shore (Dobruja Seismologic Observatory). Changing the receiving site produced insatisfactory monitoring data, characterized by large fluctuations of the received signals intensities. Trying to understand this behavior has led to the conclusion that the electric component of the electromagnetic field was possibly influenced by the local atmospheric conditions (as aerosols concentration could be). Starting from this observation we have run some tests which have indicated that a loop-type antenna is more appropriate than a vertical antenna, especially for highly electric-field polluted environments. Very good results were obtained with this new configuration, even in the site located at the Black-Sea shore.
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