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THE INFREP EUROPEAN VLF/LF RADIO MONITORING NETWORK - PRESENT STATUS AND PRELIMINARY RESULTS OF THE ROMANIAN MONITORING SYSTEM
No full textThe paper presents the Romanian VLF / LF monitoring system consisting in a radio receiver - made by Elettronika S.R.L. (Italy) and provided by the Bari University - and the infrastructure that is necessary to record and transmit the collected data. This system is a part of the international initiative INFREP. Through this initiative, originated in Italy, VLF / LF radio receivers are deployed in different locations in Europe. Each one is monitoring up to ten different transmissions of radio stations across the continent. 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 ionosphere influences on the electromagnetic waves' propagation along a certain path is a method to put into evidence possible modifications of ionosphere lower structure and composition as earthquakes' precursor.
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-w = 6.3). Since then, the receiver was relocated from Bucharest to the Black-Sea shore (Dobrogea Seismologic Observatory). Changing the receiving site produced unsatisfactory 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' concentrations 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. Future improvements of the receiver analog front-end are still possible in order to get better monitoring data by rejecting the off-band noise induced by the aerial high-voltage lines that are surrounding the site, so that for us to accomplish the best achievable surveillance in VLF / LF bands, related to seismo-electromagnetic phenomena
RILEVAMENTI GEOMAGNETICI E GEO-PETROGRAFICI NELL' AREA DI AFFIORAMENTO DELLA PIROCLASTITE DI RAIANO (CONCA PELIGNA , L'AQUILA, ABRUZZO)
No full textAn overview on preseismic anomalies in LF radio signals revealed in Italy by wavelet analysis
No full textSince 1996. the electric field strength of the two broadcasting stations MCO (f=216 kHz, southeast France) and CZE (f=270 kHz. Czech Republic) has been sampled every ten Minutes by a receiver (AS) located in central Italy. Here. we review the results obtained by a detailed analysis applied to the data recorded from February 1996 up to December 2004. At first, the daytime and nighttime data were extracted and then. in the daytime data. the data collected in winter were separated from those collected ill summer. Oil the second step the wavelet transform was applied. The results of this analysis are radio anomalies detected as earthquake precursors both for MCO and CZE data. In particular. regarding the MCO data. the main result was the appearance of a very clear anomaly during May-August 1998, at daytime and at nighttime. Such ail anomaly can be considered as a precursor of a seismic sequence started on August 15, 1998 with 17 earthquakes (M=2.2-4.6) on the Reatini mountains, a seismogenic zone located 30 kill far from the AS receiver along the path MCO-AS. As concerns with the CZE data. the first result was obtained from the summer daytime data and it was the appearance of a very clear anomaly during August-September 1997, that call be considered a precursor of the two earthquakes with magnitude M=5.6 and M=5.9 that occurred on September 26 in the Umbria-Marche region (Central Italy). The second result was the appearance of an anomaly during February-March 1998, at daytime and at nighttime, that can be related to the preparatory phase of the strong (M=5.1-6.0) Slovenia seismic sequence that occurred in a zone lying in the middle of the CZE-AS path
VARIATIONS IN THE RELATIONSHIP OF SEISMIC VELOCITIES BEFORE TWO EARTHQUACKES IN UMBRIA (ITALY).
No full textAnomalie inclinometriche e attività sismica nell'Appenninocentrale nel periodo 1991-1992
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Normal and anomalous behaviour of electric, magnetic and seismoacoustic signals recorded in the Amare cave
No full textSince 1987 multichannel instrumentation has been recording electromagnetic and seismoacoustic emissions in the Amare cave (Gran Sasso - L'Aquila). Equipment detecting RMC (Principality of Monaco) longwave broadcasting (216 kHz) has been operating in the same place. Data collected during this period have pointed out two different phenomena called «quiet» and «perturbed» that characterize the normal behaviour of the cave. On 25 August 1992 an earthquake with M = 3.9 occurred in the Gran Sasso area and on 4 June 1993 an earthquake with M = 4.3 occurred in Umbria, 100 km to north of the Amare cave. Before these earthquakes, electromagnetic, seismoacoustic, and RMC data showed anomalies. Here we present the observed phenomenology and discuss the possibility that the anomalies can be considered precursors of the earthquakes
Possible Variazions of altitude observed on the occasion of the Tohaku earthquake (M=9.0) occurred on march 11, 2011
No full textMisure di inclinazione del suolo e probabili creep asismici in faglia, precursori dei principali terremoti avvenuti nell’Appennino Centrale e nel Caucaso Meridionale
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