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Titel |
Disturbances in a VLF radio signal prior the M=4.7 offshore Anzio (central Italy) earthquake on 22 August 2005 |
VerfasserIn |
P. F. Biagi, L. Castellana, T. Maggipinto, D. Loiacono, V. Augelli, L. Schiavulli, A. Ermini, V. Capozzi, M. S. Solovieva, A. A. Rozhnoi, O. A. Molchanov, M. Hayakawa |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1561-8633
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Digitales Dokument |
URL |
Erschienen |
In: Natural Hazards and Earth System Science ; 8, no. 5 ; Nr. 8, no. 5 (2008-10-10), S.1041-1048 |
Datensatznummer |
250005768
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Publikation (Nr.) |
copernicus.org/nhess-8-1041-2008.pdf |
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Zusammenfassung |
On 22 August 2005 an earthquake with magnitude M=4.7 occurred in the
Anzio (central Italy) offshore area. From 2002, a VLF-LF radio receiver is
into operation in Bari (southern Italy). The intensity and the phase of the
signals transmitted by GB (f=16 kHz, United Kingdom), FR
(f=20.9 kHz, France), GE (f=23.4 kHz, Germany), IC
(f=37.5 kHz, Island) and IT (f=54 kHz, Sicily, Italy) has been
monitored with a 5 s sampling rate. The previous epicenter is near enough to
some of the radio paths and the data collected were studied in order to
reveal possible seismic effects. The raw analysis revealed a clear drop in
the intensity of the FR radio signal on 19 August. Then the wavelet analysis
was applied to the intensity and the phase data of the different radio
signals. In the mentioned day an increase in the band 60–120 min was
revealed in the spectra of the FR signal. Then the principal component
analysis was applied and again the 19 August stood up as an anomalous day for
the FR radio signal. The path of this signal, among the paths of the five
radio signals collected by the Bari receiver, is the nearest to the mentioned
epicentre and the anomaly revealed on 19 August appears as a precursor of the
earthquake. This result confirms the possible precursor revealed by other
researchers in the air Rn content in a site located 5 miles far from the
epicenter. |
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