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Legends speak of a Brazilian magnetic island capable of disorienting compasses and diverting aircraft. We investigate Trindade Island and the science behind these supposed extraordinary phenomena.
The idea of a magnetic island in Brazil, a mysterious place that drastically interferes with navigation, is a popular idea. Reports of compasses “going crazy” and planes diverting their routes create an aura of enigma. But could such an island exist in Brazil capable of such feats?
Scientific investigations point to Trindade Island, a remote volcanic formation in the Atlantic, as the likely candidate for this fame. This article explores the geology of the Trinity and the facts behind the legend of Brazilian magnetic island.
Brazilian magnetic island
Located approximately 1.100-1.200 km off the coast of Espírito Santo, Trindade Island is the youngest volcanic manifestation of the Vitória-Trindade Chain. Its geological formation is complex, the result of multiple volcanic episodes, the most recent occurring about 300.000 years ago. The predominant rocks are alkaline, such as phonolites and nepheline syenites, and studies have confirmed the significant presence of ferromagnetic minerals, such as magnetite and titanomagnetite.
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These minerals give the island's rocks the ability to generate or alter the local magnetic field, mainly through the thermoremanent magnetization acquired during the cooling of the lavas. This is the geological basis for Trindade's potential to be considered a Brazilian magnetic island.
Earth's magnetic field
The Earth's magnetic field, generated in its core, can present local variations in the crust, known as crustal magnetic anomalies. A volcanic island like Trindade is naturally expected to be the source of such anomalies.. It is crucial, however, to distinguish these local disturbances from the South Atlantic Magnetic Anomaly (SAMA).
The AMAS is a vast area of weakening of the main magnetic field, originating in the Earth's core, mainly affecting satellites. Although Trindade Island is in the AMAS region, the magnetic effects that could be felt locally would be primarily due to its own geology. Paleomagnetic and magnetic susceptibility anisotropy (MSA) studies on the island confirm the magnetic nature of its rocks.
“Crazy” compasses and hijacked planes
Theoretically, strong local magnetic anomalies can affect magnetic compasses, causing deviations or erratic behavior. However, modern navigation systems such as GPS are not directly affected by crustal magnetic fields, although geomagnetic storms (potentially more intense in the AMAS) can cause inaccuracies in GPS signals.
A rigorous investigation into the available data does not reveal official reports from the Brazilian Navy or DECEA documenting serious incidents navigational errors unequivocally attributed to magnetic anomalies on Trindade Island. Nautical and aeronautical charts of the region indicate standard magnetic declination, but there are no specific warnings about extraordinary disturbances that would make Trindade a dangerous Brazilian magnetic island for routine navigation.
Pirate treasure to the “Brazilian magnetic island”
Trindade Island, remote and volcanic in appearance, is fertile ground for legends. Stories of hidden pirate treasures, such as the “Trinity Treasure”, are famous and contribute to their aura of mystery. It is possible that navigation difficulties faced by navigators of the past, with more rudimentary instruments, were attributed to mysterious forces and incorporated into folklore.
The narrative of Brazilian magnetic island may be a manifestation Modern of these legends, where real volcanic geology and the existence of AMAS provide a “scientific” veneer to older tales of an “enchanted” island.
