Characteristic ULF Band Magnetic Field Variations at MPGO, Ghuttu for the 20 June 2011 Earthquake in Garhwal Himalaya

Magnetic field variations recorded at the Multi Parameter Geophysical Observatory (MPGO), Ghuttu, using digital fluxgate magnetometer are studied in the frequency band 0.03-1 Hz and for 19-20 h UT for June 2011. Polarization analysis based on planar wave assumption for far field is applied in order to discriminate seismo-magnetic signatures. The dynamics of earthquake processes, considering them as selforganized critical systems, is also studied using fractal dimension of ultra-low frequency band geomagnetic field variations. Marginal increase in polarization ratio and fractal dimension a few days before the earthquake is significant against the background of global geomagnetic activity. At the same time, the effect of post-seismic readjustment of seismogenic processes is clearly marked by significant changes in fractal dimension and increased polarization ratio after the earthquake.