The resulting electromagnetic field can be either aligned with the Earth, or set to cross the Earth's magnetic field, or at any partial angle that the scientists desire. Depending on the strength of the Earth's own magnetic field, the field created by the instruments is thus disrupted or weakened. This weakening disruption, noted by scientists, is just another indication of the dispersal of the Earth's internal magnetic field. We have stated that the heating up of your world's oceans are related to the increased swirling about going on in the Earth's core. Even primitive humans were intuitively aware that the Earth's core was not solid.
Molten lava is a sure clue.
Even during quiescent times the liquid rock that lies under the crusted surface of the Earth moves about, just as currents move in the oceans. The oceans are not merely influenced by temperature changes from contact with molten lava on the ocean floor or air temperature, but also by pressure to some degree from the prevailing winds. Most importantly, the oceans are pulled to and fro by the gravity of the Moon and other planetary bodies. Once set in motion, water tends to keep moving for some time, high pressure areas dispersing to low pressure areas, just as in the atmosphere. Likewise, molten rock in the Earth's core is subject to influences - gravitational, from other planetary bodies, but also magnetic, as the composition of the molten rock contains elements such as iron prone to magnetic influences.