Electromagnetic radiation (EMR) as a tool to determine directions of horizontal principal stress and active faults in the high seismicity region of Kachchh (India)
Mallik, Jyotirmoy; Mathew, George; Angere, Thomas; Greiling, Reinhard O.
The Kachchh basin in western India is known for its recent high seismicity. This study presents an application of the geogenic electromagneticradiation (EMR) technique for decipheringthe directions of principal horizontal stress in the eastern Kachchh. This study is based on linear profiling at six different places across two major faults, the Kachchh mainland fault (KMF) and the south Wagad fault (SWF) in the eastern Kachchh. The principal direction of horizontal stress obtained from EMR differs from those obtained from earthquake focal plane solutions. The major horizontal principal stress based on the EMR study shows an azimuth of 60± 10°. The principal directions of EMR emissions are parallel to the acute bisector of conjugate microcracks. The azimuthal distribution of EMR signals and dimension of microcracks suggest that the EM emissions are transversely polarized. The study also deals with the first application of electromagneticradiation emissions to identify active fracture planes in sandstones that may become active, seismogenic or non-seismogenic, faults in the future. Anomalouslyhigh EM emissions are observed in the eastern part of the KMF, indicating active surface deformation.