the central italy electromagnetic network and the 2009 laquila earthquake observed electric activity意大利中部的电磁网络和2009年的拉奎拉地震观测到电活动.pdf

Geosciences 2012, 1, 3-25; doi:10.3390/geosciences1010003 OPEN ACCESS geosciences ISSN 2076-3263 /journal/geosciences Article The Central Italy Electromagnetic Network and the 2009 LAquila Earthquake: Observed Electric Activity Cristiano Fidani Physics Department, Perugia University, Via A. Pascoli, Perugia 06123, Italy; E-Mail: c.fidani@virgilio.it; Tel.: +39-075-585-2757; Fax: +39-075-585-2719 Received: 19 September 2011; in revised form: 31 October 2011 / Accepted: 5 December 2011 / Published: 8 December 2011 Abstract: A network of low frequency electromagnetic detectors has been operating in Central Italy for more than three years, consisting of identical instruments that continuously record the electrical components of the electromagnetic field, ranging from a few Hz to tens of kHz. These signals are analyzed in real time and their power spectrum contents and time/frequency data are available online. To date, specific interest has been devoted to searching for any possible electromagnetic features which correlate with seismic activity in the same region. In this study, spectral analysis has evidenced very distinct power spectrum signatures that increased in intensity when strong seismic activity occurred near the stations of the 2009 LAquila earthquake. These signatures have revealed horizontally oriented electric fields, between 20 Hz to 400 Hz, lasting from several minutes to up to two hours. Their power intensities have been found to