کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4720942 1639350 2015 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Seismo-meteo-electromagnetic phenomena observed during a 5-year interval around the 2011 Tohoku earthquake
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Seismo-meteo-electromagnetic phenomena observed during a 5-year interval around the 2011 Tohoku earthquake
چکیده انگلیسی


• Seismo ULF radiation is observed prior to the 2011 Tohoku earthquake.
• ULF radiation is detected in the Z component of magnetic field.
• Its seasonal variation shows winter maxima.

The purpose of the paper is to try to find ULF electromagnetic precursors to the 2011 Tohoku earthquake (EQ), on the basis of extensive investigation of radiations in vertical component of the magnetic field or with a large ratio of the vertical to full horizontal component. Nighttime records have been analyzed of three Japanese fluxgate magnetometers located in a distance from 300 to 1300 km from the epicenter of the main shock, and the frequency range from 10 to 150 mHz was used for the analysis. We have applied wavelet analyses to improve the detection of pulsed signals. All obtained scalograms have been averaged over the nighttime interval from 01 h to 05 h JST and flattened by means of multiplication by square of frequency. The sequence of spectra thus obtained has been compared with the evolution of seismicity, which has resulted in that the radiation in the vertical component has been detected. It exhibits seasonal variations with winter maxima, but it increases further by approaching the moment of the EQ and decreases after that. This radiation seems to be correlated with atmospheric parameters – air humidity, temperature, vapor pressure and rainfall. So, we consider that this radiation cannot be caused by subsurface sources, but its possible sources can be atmospheric discharges. The evolution of this phenomenon can be explained by a seasonal variation of atmospheric parameters and also its variations under the influence of injection of gas from the focal zone of a forthcoming EQ.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics and Chemistry of the Earth, Parts A/B/C - Volumes 85–86, 2015, Pages 167–173
نویسندگان
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