1. Geophysical Center of the Russian Academy of Sciences (GC RAS), 119296 Moscow, Russia
2. Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS), 119296 Moscow, Russia
3. College of Mining, National University of Science and Technology MISIS, 119049 Moscow, Russia
4. Geophysical Institute, Vladikavkaz Scientific Center RAS (GPI VSC RAS), 362002 Vladikavkaz, Russia