1541 Tsunami: Sao Vicente, Brazil

Reference #14100 [unofficial translation]:

It was the Benedictine monk Friar Gaspar da Madre de Deus who first reported that several buildings in Vila de Sao Vicente didn't last long because the sea took everything away (Madre de Deus, 2010). Much later, the historian Mario Neme (1954), when discussing the controversy over the location of the old Porto das Naus, near the town of Sao Vicente, suggested that the disaster could have been caused by a tsunami or a strong surge/agitation/swell [term used in the publication is “ressaca”]. In another part of his studies, Neme concluded that strong marine erosion had allowed the sea to advance definitively into those lands and drew a map of what had happened. More recently, Eduardo Bueno (1999) relived the episode, saying that a tsunami submerged a large part of the village, when witnesses saw the arrival of waves eight meters high that advanced inland for around 150 meters, destroying houses and other buildings. He reproduced the map of the flooded area drawn up by Mario Neme, but didn't say how he estimated the height of the waves and their advance on the mainland. However, Friar Gaspar's writings reinforce the idea that the waters arrived suddenly, with no time to remove anything: “[...] 50 reis were spent to remove the bells from the sea and the pillory from the beach; 20 reis to transport them to the new town and 250 reis to rebuild the pillory with stone, clay and water”.

Was it really a tsunami?

None of the historical information mentioned the perception of any earthquake, nor did it give any information about the weather conditions that day. The flooded area could have covered several square kilometers if the flood had gone beyond the village limits, but this is not known. Given the local damage, the height of the waves and the area covered by seawater, it would seem admissible to correlate these effects as the work of a localized tsunami, with action restricted to a part of the Sao Paulo coastline. But what could have produced these waves? In the case of a seismic source, it would be difficult to define the location and magnitude of the earthquake, which would not have been small. We could include the possibility of an underwater landslide, but the difficulty in defining this is just as problematic as the previous one.

Another less spectacular way of explaining what happened is through a violent surge/agitation/swell , which is more common than not in that region. Extratropical cyclones often cause powerful surges/agitations, and the Brazilian coast has witnessed countless of them, some with significant physical and material losses. Abnormal atmospheric conditions can be associated with high tides and also cause vigorous waves against the coast, or generate storm waves offshore, which eventually grow even larger near the coast, depending on the ocean topography.

Thus, by the process of elimination, a violent surge/agitation/swell would seem to be the best explanation for the 1541 episode, considering the knowledge we have at the moment.

NOTE: lat/long in database for this event is an only based on proximity to only known wave observations