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| Titel |
A possible preseismic anomaly in the ground wave of a radio broadcasting (216 kHz) during July-August 1998 (Italy) |
| VerfasserIn |
P. F. Biagi, L. Castellana, T. Maggipinto, R. Piccolo, A. Minafra, A. Ermini, S. Martellucci, C. Bellecci, G. Perna, V. Capozzi, 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 ; 5, no. 5 ; Nr. 5, no. 5 (2005-09-28), S.727-732 |
| Datensatznummer |
250002799
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| Publikation (Nr.) |
 copernicus.org/nhess-5-727-2005.pdf |
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| Zusammenfassung |
| On February 1996, a receiver able to measure the electric field strength of
LF radio broadcastings, with a sampling frequency of ten minutes, was put
into operation in a site (AS) located in central Italy. One of the
broadcasting stations selected is MCO (f=216 kHz), located in southeast
France, 518 km far from the receiver. The MCO data collected since February
1996 up to September 2004 were examined and, at first, the night time data
and the day time data (in winter and summer) were separated. Then, the
wavelet analysis on the night and day time data was applied. The main result
of the analysis was the appearance of a very clear anomaly during summer
(July–August) 1998, at day time and at night time. The anomaly is a strong
exaltation of the signal components with period in the 25–40 days range.
Theoretical calculations of electric field strength were made and the only
way to justify this anomaly seems to be the occurrence of an increase of the
ground wave propagation mode of the radio signal. Such an increase could
have been produced by an increase of the ground conductivity and by
modifications of some parameter of the troposphere, mainly the refractive
index. On 15 August 1998 a seismic sequence started with 17 earthquakes
(M=2.2–4.6) on the Reatini mountains, a seismogenic zone located 30 km far
from the AS receiver along the path MCO-AS. In this paper, the possibility
that the previous radio anomaly can be a precursor of this seismic sequence
is proposed.
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