1. CSIR‐National Geophysical Research Institute, Hyderabad 500007, India, karora_ngri@yahoo.co.uksrinu.geotech35@gmail.comgopinadh840@gmail.comrajen0555@gmail.comharisraza90@gmail.com
2. Schmidt Institute of Physics of the Earth Russian Academy of Sciences, 10 B. Gruzinskaya, Moscow 123242, Russia, mikh@ifz.ruavp@ifz.ru
3. Also at Lomonosov Moscow State University, Department of Physics, 1 Leninskie Gory, Moscow 119991, Russia; vs60@mail.com.