Electromagnetic Geophysics

Electromagnetic Geophysics studies the properties of the electromagnetic environment of the Earth and utilizes the response of the Earth to changes in EM signals with a view to decipher the subsurface conductive structure at multi-scales from a few meters below the ground surface to several hundred kilometers depths in order to explore natural resources as well as to understand the fundamental geodynamic processes. Prior to 1970, when there were just a few electromagnetic instruments in the world, CSIR-NGRI was the first to design, fabricate and install one such modern facility that attracted the attention of all electromagnetic experts in India and beyond. NGRI’s leadership in the field of airborne magnetic surveys continued with focus around in-house design and development of a range of precise magnetometers and sensors, in 1966. Magneto-telluric and geomagnetic induction studies were initiated using in-house instruments and observatory records. NGRI conducted very precise survey to chart out the magnetic equator and these results were published in ‘Nature’. A pioneering project comprised aeromagnetic surveys and mapping of iron ore formations along Karnataka Sahyadris deploying proton precession magnetometer, a 35 mm camera, and a scintillometer mounted on a Dakota DC-3 aircraft was accomplished in the early years of the Institute.

The Electromagnetic Geophysics group at CSIR-NGRI is actively engaged in pursuing studies for delineating conductive structures mainly specific to the Indian continental region for exploration of hydrocarbon and minerals, understanding of seismically active intraplate and plate boundary regions, imaging of Indian cratons, precursory studies and geomagnetism. Apart from the state-of-art broadband and long period magnetotelluric (MT) equipment, the group is equipped with a heli-borne Versatile Transient Electromagnetic (VTEM) system for airborne exploration. A permanent geomagnetic observatory, which is a part of a global network, is being operated by the Electromagnetic Geophysics group of CSIR-NGRI.