The regional water authority, Administração da Região Hidrográfica (ARH), has not been able to determine the direct causes of a rock fall at Maria Luísa beach, which killed five people on August 21.
According to a report released by ARH, what happened was a rare accident and there were no warning signs that a collapse could occur.
The report suggests however that the earthquake of 4.2 on the Richter scale, which happened three days earlier, could have contributed to the collapse.
