More recently, between 1968 and 1972, the Campi Flegrei area suffered an episode of positive bradyseism and rose by 1.7 metres. Another rise of 1.8 metres occurred between 1982 and 1984. This correlated with a shallow (4 km deep) earthquake swarm during the same period, which led to the evacuation of 30,000 people due to the perceived risk of imminent eruption.