1. Departamento de Geofisica do Insituto de Astronomia Geofisica e Ciencias AtmosfericasUniversidade de São Paulo, IAGSão Paulo Brazil
2. Now at School of Geography, Earth and Environmental Sciences (SoGEES), Plymouth UniversityPlymouth UK
3. Department of Earth Science and Engineering, Natural Magnetism GroupImperial College of LondonLondon UK