Variations of induction vector in seismoactive regions

: pp. 90 - 92
Received: August 01, 2012
Subbotin Institute of geophysics of National Academy of Sciences of Ukraine
Subbotin Institute of geophysics of National Academy of Sciences of Ukraine
Subbotin Institute of geophysics of National Academy of Sciences of Ukraine

Purpose. In world practice there are observations of variations of induction vectors related to geodynamic processes. The purpose of this work is to compare time series of induction vector components at two Japanese stations Esashi (ESA) and Mizusawa (MIZ), located on the east coast of Honshu island at a distance of 19 km from each other, with a seismic activity in the region. Methodology.  Processing of 1 second data of three-component magnetic field with a three-day smoothing were carried out to get induction vectors for different periods by means of multi-functional program of Varentsov I.M. Since the values of induction vector components may be dependent on the magnetic activity, the data of January – September 2009 were taken – at that time magnetic field has been relatively quiet, average index of geomagnetic activity Kp was equal 2. On this background, it was possible to identify induction vectors changes that can have intraterrestrial origin more reliably. Shallow-focus earthquakes (depth up to 50 km) with a magnitude 4≤M<5 that occurred at a distance <150 km to the station and the earthquakes M≥5 at a distance <250 km were considered. Results. Obtained results showed that on short periods less than 50 s during the selected interval of time induction vector was not constant, but its variations were occurring at the moments of some considered earthquakes. Depending on the distance from the station to the epicenter and the spatial distribution of earthquakes sources, real and imaginary components of vectors changed differently. These changes could be caused by a change in the electrical conductivity of the Earth's lithosphere, related to tectonic processes, as well as lithospheric emission origin – ultra low frequency magnetic fields, which carry information about the earth interior and processes occurring in it. Originality. This paper presents new results on the relation of electromagnetic field variations with seismic activity. Practical significance. Research results open the prospect of induction vectors using as an earthquake precursor.

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