Anomalous geomagnetic field variations in electric conductivity of the Earth associated with seismicity

   Long-term monitoring of geomagnetic field variations has been carried out
   at 8 sites in the southern part of Baikal rift. Observation data provide
   an opportunity to study the change in geomagnetic field intensity across
   the rift strike at the distance of 170 km. The analysis is based on
   secular variation of geomagnetic field H, D and Z components recorded at
   Patrony Ground Observatory in 1968-2011. The behavior of secular variation
   of geomagnetic field vertical component in 1998-2011 has an anomalous
   change that may be due to intensification of geodynamic processes caused
   by high seismic activity in the southern part of the rift in 1998-2006.

   A comparative analysis of geomagnetic field full vector intensity in
   Patrony, Sukhoi Ruchei, Khuramsha and Nadeino, i.e. on the profile across
   the rift strike, has been carried out. Anomalous changes (around 8 nT) in
   the geomagnetic field were observed over the last 9 years. These changes
   indicate the intensification of geodynamic processes in the southeastern
   part of the rift.

   Geomagnetic variations with periods from the first minutes to the first
   hours, recorded by the Patrony Ground Observatory, have been used to study
   electrical conductivity dynamics of the lithosphere. This study is based
   on transfer function between the vertical and horizontal components of
   geomagnetic field variations, termed magnetic tipper. To study the
   magnetic tipper dynamics, continuous time series of H, D and Z components
   with 1-minute rate for 2001-2011 were used. The magnetic tipper monitoring
   has been carried out in the period range from 143 to 10000 s. The real
   tipper behavior at the periods of 143 and 210 s showed anomalous changes
   during the Kultuk earthquake. The anomaly is characterized by tipper
   increase in relation to the long-term level of real tipper. It is
   characteristic that the tipper anomaly appeared only in short-period
   range. A rough estimate of the length of an electromagnetic wave is the
   first hundreds of kilometers. Therefore, the magnetic tipper reflects the
   change in geological medium electrical conductivity including the southern
   part of the lake affected by the Kultuk earthquake. The wave penetration
   depth at such length is the first tens of kilometers. Supposedly, the
   tipper controls the electrical conductivity of the Earth's crust in the
   southern part of Baikal basin. Rough qualitative estimates by 3D-numerical
   model of the Baikal basin show, that conductivity short-term enhancement
   of a deep fault in the southern part of the lake is required for real
   tipper change. Moreover, it is not inconceivable that transfer function
   can be disrupted between the vertical and horizontal components of the
   field due to the occurrence of lithospheric-ionospheric connections caused
   by the large Kultuk earthquake.