Kalachand Sain, Chief Scientist & Head, Seismic Group, Council of Scientific and Industrial Research (CSIR)-National Geophysical Research Institute (NGRI), Uppal Road, Hyderabad, India. Damodara Nara, DST-INSPIRE faculty, Council of Scientific and Industrial Research (CSIR)-National Geophysical Research Institute (NGRI), Uppal Road, Hyderabad, India.