Latest ‘lithospheric magnetic field map’ by ESA’s Swarm mission shows detailed variations in this field more precisely than previous satellite-based reconstructions, caused by geological structures in Earth’s crust. One of these anomalies occurs in Central African Republic, centred on the city of Bangui, where the magnetic field is significantly sharper and stronger. The cause for this anomaly is still unknown, but some scientists speculate that it may be the result of a meteorite impact more than 540 million years ago. See more at http://www.esa.int/Our_Activities/Observing_the_Earth/Swarm/Unravelling_Earth_s_magnetic_field
