4 February 2011 Is the strengthened spectrum at cut-off frequency in daytime electromagnetic field a precursor of strong earthquakes?
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Proceedings Volume 7752, PIAGENG 2010: Photonics and Imaging for Agricultural Engineering; 77520D (2011) https://doi.org/10.1117/12.889252
Event: International Conference on Photonics and Image in Agricultural Engineering (PIAGENG 2010), 2010, Qingdao, China
Abstract
Based on two case studies recorded by DEMETER satellite in 2006 and long time series comparison, some increases and decreases in electric field power spectra were revealed before two strong earthquakes. We focus on the electromagnetic field spectra at 300-500Hz around cut-off frequency during local daytime. The results show that, compared with the normal background, the electromagnetic emissions decreased at ionospheric altitude(660km) in a month before the events, and there are a few days with electric field spectra increasing, larger than 101.5μV2 / m2 / Hz. In order to get more reliable results in anomaly extracting, the study of temporal evolutions of electromagnetic emission at cut-off frequency, as well as monthly and seasonal variations should be studied, besides the short time behaviors. Finally the mechanism of long time variations in electromagnetic field in ionosphere was discussed.
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Xuemin Zhang, Xuhui Shen, Roberto Battiston, Michel Parrot, Zhima Zeren, "Is the strengthened spectrum at cut-off frequency in daytime electromagnetic field a precursor of strong earthquakes?", Proc. SPIE 7752, PIAGENG 2010: Photonics and Imaging for Agricultural Engineering, 77520D (4 February 2011); doi: 10.1117/12.889252; https://doi.org/10.1117/12.889252
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