Institute of Space and Atmospheric Studies, University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada

on leave from: Institute of Seismology, al-Farabi, 75a, 050060, Almaty, Kazakhstan

Institute of Space and Atmospheric Studies, University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada

Department of Physics, La Trobe University, Melbourne, Victoria, 3086, Australia

Institute of Space and Atmospheric Studies, University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada