[1] Russian Acad Sci, Inst Geosphere Dynam, Moscow 119334, Russia
[2] Kyrgyz Russia Slav Univ, Bishkek 720000, Kyrgyzstan
[3] Russian Acad Sci, Inst Space Res, Moscow 117810, Russia
[4] Karlsruhe Inst Technol, D-76344 Eggenstein Leopoldshafen, Germany