Ultra-Low Frequency Geomagnetic Variations before Dholavira Earthquake M = 5.1 on the 20th of June 2012 in Kachchh Region, Gujarat, India

Research reveals that ultra-low frequency (ULF) geomagnetic variations, distinct from global geomagnetic effects or atmospheric disturbances, occurred before the 2012 Dholavira earthquake (M = 5.1) in Gujarat, India. Analysis of high-resolution magnetic data from a geophysical observatory showed increased polarization ratio variability and enhanced Pc3 amplitude ratios seven days prior to the quake, alongside slight increases in fractal dimensions. These anomalies were not linked to geomagnetic storms or lightning, suggesting a seismic origin. The study employed midnight magnetic data (18–21 UT) from January to July 2012, filtered for anthropogenic noise, and applied polarization analysis and fractal dimensional analysis to distinguish seismo-magnetic signatures.

Joshi, Sh., & Madhusudhanarao, K. (2021). Ultra-Low Frequency Geomagnetic Variations before Dholavira Earthquake M = 5.1 on the 20th of June 2012 in Kachchh Region, Gujarat, India. Geotectonics, 55(4), 633–645. https://doi.org/10.1134/s0016852121040142