Decrease in the electric intensity of VLF/LF radio signals and possible connections
Decrease in the electric intensity of VLF/LF radio signals and possible connections
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VLF/LF 无线电信号的电场强度降低以及可能的连接
DOI：
10.5194/nhess-7-423-2007
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发表时间：
2007
影响因子：
4.6
通讯作者：
M. Hayakawa
中科院分区：
文献类型：
--
作者：
P. Biagi;L. Castellana;T. Maggipinto;Gianni Maggipinto;A. Minafra;A. Ermini;V. Capozzi;G. Perna;M. Solovieva;A. Rozhnoi;O. Molchanov;M. Hayakawa
抽象的。2002年2月，巴里大学（意大利南部）物理系的一台接收机投入使用，以记录甚低频-低频无线电信号。GB（f=16 kHz，英国）、FR（f=20.9 kHz，法国）、GE（f=23.4 kHz，德国）、IC（f=37.5 kHz，冰岛）和IT（f=54 kHz，西西里，意大利）发射的信号的强度和相位已被监测，采样率为5 s。分析了2002年2月至2006年4月10分钟平均强度原始数据。无线电信号的电场强度的几次下降，持续了几天，通常发生在不伴随的时期。GE信号在每年的冬、夏两季有系统地衰减，因此，可以认为这种衰减与发射器有关。相反，所指出的所有其他减少都是零星的，以前的理由似乎不现实。在这些下降发生的时间，地磁活动，在接收区的气象条件和区域地震活动进行了调查。主要的结果是，一般来说，地震前或地震后的影响似乎给出了最令人信服的理由。当震中位于射电信号的第三菲涅耳带内或足够靠近某些射电路径时，M≥4.3级的地震似乎出现了这种效应。
Abstract. In February 2002, a receiver was put into operation at the Department of Physics of Bari University (Southern Italy) to record VLF-LF radio signals. 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 intensity raw data averaged over 10 min, from February 2002 to April 2006, have been analysed. Several decreases of the electric field intensity of the radio signals with a duration of some days were revealed, generally occurring in not concomitant periods. The GE signal decreases systematically in winter and summer each year and so, it could be supposed that such decreases are related to the transmitter. On the contrary, all the other decreases pointed out are sporadic and the previous justification does not seem realistic. On the time occurrence of these decreases, the geomagnetic activity, the meteorological conditions in the receiver area and the regional seismic activity were investigated. The main result is that, generally, a pre or post seismic effect seems to give the most convincing justification. The effect seems to appear for earthquakes with magnitude M≥4.3, when the epicentres are within the third Fresnel zone of the radio signals or near enough to some radio path.