Table 1. List of magnetometer stations used in this work

Station name Station code Belongs to Geog. Lat. Geog. Long. Geom. Lat. Geom. Long.
Magnetometers stations in the Peruvian sector
 Huancayo HUA INTERMAGNET 12.1°S 75.3°W 0.14°S 357.33°E
 Piura PIU IGP 5.2°S 80.6°W 6.45°N 352.23°E
 Leticia LET LISN 4.2°S 69.9°W 6.59°N 3.33°W
Magnetometers stations in the Brazilian sector
 Tatuoca TTB WDC Catalogue 1.21°S 48.5°W 0.19°N 24.27°E
 Kourou KOU INTERMAGNET 5.21°N 53°W 8.46°N 22.06°E
Magnetometers stations in the West African sector
 Samogossoni SAM WAMNET 11.39°N 5.62°W 0.54°S 68.82°E
 Tamanrasset TAM INTERMAGNET 22.8°N 5.5°W 12.93°N 80.2°E
Magnetometers stations in the East African sector
 Addis Ababa AAE INTERMAGNET 9.04°N 38.8°E 0.93°N 112.39°E
 Adigrat ETHI AMBER 14.3°N 39.5°E 6.89°N 112.8°E
Magnetometers stations in the Indian sector
 Tirunelveli TIR SuperMAG 8.48°N 76.95°E 1.05°N 149.73°E
 Alibag ABG INTERMAGNET 18.62°N 72.87°E 12.40°N 145.88°E
Magnetometers stations in the Southeast Asian sector
 Langkawi LKW SuperMAG 6.3°N 99.78°E 1.42°S 172.37°E
 Kototabang KTB SuperMAG 0.2°S 100.3°E 8.55°S 172.81°E
 BacLieu BCL SuperMAG 9.3°N 105.7°E 2.05°N 178.21°E
 Qiongzhong QGZ WDC Catalogue 19°sN 109.8°E 12.54°N 182.42°E
Magnetometers stations in the Philippines sector
 Davao DAV SuperMAG 7°N 125.4°E 0.42°S 197.64°E
 Muntilupa MUT SuperMAG 14.37°N 121.02°E 7.47°N 193.39°E
 Legazpi LGZ SuperMAG 13.1°N 123.7°E 6.05°N 196.02°E
 Kakadu KDU INTERMAGNET 12.69°S 132.47°E 21.45°S 211.88°S
Magnetometers stations in the Pacifc sector
 Yap YAB SuperMAG 9.3°N 138.5°E 1.66°N 210.65°E
 Guam GUA INTERMAGNET 13.59°N 144.9°E 6.11°N 216.83°E
The computed coordinates presented here are based on the Geomagnetic Coordinates IGRF-13 revised in December 2019 using the epoch of 2013 (data from British Geological Survey 2019).