Evaluation of maximum horizontal near-surface stress (SHmax) azimuth and its distribution along Narmada-Son Lineament, India by geogenic Electromagnetic Radiation (EMR) technique

The Narmada-Son rift (also known as the Narmada-Son Lineament or NSL) is a significant geological feature of peninsular India. Although the origin of this feature dates back to the Precambrian time, it is still very much tectonically active as manifested by recurrent earthquakes of moderate to high magnitude (between 3 to 6.5 on Richter scale). One such well-known episode is the Jabalpur Earthquake of 1997 (magnitude 6.0). There are twenty existing maximum horizontal stress (SHmax) azimuth data available in this region from three different sources: 1) calculated from the hydro-fractures (SHmax azimuth = N73 degrees E, depth = 0.35 km) from an 800 m deep borehole from Malanjkhand area, 2) calculated from Jabalpur earthquake (Depth = 38 km) focal point solution (SHmax azimuth = N164 degrees E) 3) Obtained from fault plane solution of a few selected earthquake events along the "Central India Tectonic Zone (CITZ)" using the waveform inversion technique. Since the local stress direction data are varying and location-specific which is dependent on mostly chances of occurring of an earthquake, we present a study that covers a considerable stretch of the NSL where the geogenic Electromagnetic Radiation (EMR) technique has been applied to calculate the directions of principal horizontal near-surface stresses along NSL. In this study, we have taken a total of eighteen horizontal stress measurements along the Narmada Son lineament over a stretch of 600 km with orientations varying from N15 degrees E to N170 degrees E with a mean azimuth of N85 degrees E. We document the possible reasons for the difference in stress azimuth data obtained from EMR and from other sources.