*Manuel Calvo-Rathert^1,2、Elisa Maria Sanchez Moreno¹、Maria Felicidad Bogalo¹、Avto Gogichaishvili³、George Vashakidze⁴、Emilio Herrero-Bervera²、Juan Julio Morales³ (1.Departamento de Fisica, EPS, Universidad de Burgos, 09006 Burgos, Spain、2.Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawaii, United States、3.Servicio Arqueomagnetico Nacional – Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Morelia, Mexico 、4.Alexandre Janelidze Institute of Geology – Ivane Javakhishvili Tbilisi State University, 0171 Tbilisi, Georgia)